CN1778124A - System and method for power adjustment in a wireless network. - Google Patents
System and method for power adjustment in a wireless network. Download PDFInfo
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- CN1778124A CN1778124A CN 200480010879 CN200480010879A CN1778124A CN 1778124 A CN1778124 A CN 1778124A CN 200480010879 CN200480010879 CN 200480010879 CN 200480010879 A CN200480010879 A CN 200480010879A CN 1778124 A CN1778124 A CN 1778124A
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Abstract
The performance and ease of management of wireless communications environments is improved by a mechanism that enables access points (APs) to perform automatic channel selection. A wireless network can therefore include multiple APs, each of which will automatically choose a channel such that channel usage is optimized. Furthermore, Aps can perform automatic power adjustment so that multiple Aps can operate on the same channel while minimizing interference with each other. Wireless stations are load balanced across Aps so that user bandwidth is optimized. A movement detection scheme provides seamless roaming of stations between Aps.
Description
Technical field
The present invention relates to wireless network, more specifically to radio network configuration that is used for optimization of network performance and power level adjustment.
Background technology
On knee and handhold portable formula computer universal incident is the needs to healthy and strong, reliable and high performance wireless networks, so that the mobility advantage of these equipment is maximized, and improves the formation of these wireless networks and the simplification of management.Present wireless network is subjected to limiting mobile subscriber's network performance and some restriction of reliability such as networks such as IEEE802.11b, 802.11a, 802.11g.For example, have only number very the limited wireless channel can use.Under the prior art state, because the cause that radio and control protocol are disturbed, WAP (wireless access point) can not be shared the same channel in the same area effectively.Thereby the bandwidth in the appointed area is subjected to the numerical limitations of available non-overlapped channel.In addition, present wireless network needs manual field engineering design, so that control the layout of access point and the channel distribution between the access point, has improved the cost and the complexity of wireless network installation process thus.In addition, the user who roams between WAP (wireless access point) is inconsistent.In case link with certain access point, even another access point can provide higher performance to the user, the user also will tend to keep linking with this access point.A kind of the overcome above-mentioned deficiency of current wireless network and the wireless networking solution of defective need be provided.
Summary of the invention
According to principle of the present invention, provide various device, method and computer program product to improve the management of performance and the simplification of wireless communications environment.For example, provide a kind of mechanism, make access point (AP) can carry out automatic channel and select.So wireless network can comprise a plurality of AP, each AP will select a certain channel automatically, so that the channel utilization rate is optimised.In addition, AP can carry out automated power to be regulated, and consequently a plurality of AP can work on same channel, make interference each other reduce to minimum simultaneously.Others of the present invention are used to facilitate the load balancing of the station of crossing over AP, thereby user bandwidth is optimised.Novel mobile detection scheme provides the seamless roam of the station between the AP.These and other aspect of the present invention makes it possible to provide the high performance wireless communications environment that can dispose automatically.
Description of drawings
Fig. 1 represents that wherein the wireless user is by access point (AP) and the interactive wireless communications environment of other networking gear.
Fig. 2 represents wireless user equipment wherein or the station (STA) wireless network by access point visit wireless network and shared available network bandwidth.
Fig. 3 represents that wherein the station is passed through two independently wireless networks of access point access network.
Fig. 4 is how expression AP sets up channel Mapping, supplies the flow chart of the usefulness of automatic channel selection scheme.
Fig. 5 is the flow chart of expression automatic channel system of selection.
Fig. 6 is the performance that the form of channel selection scheme use is selected in the incense of AP maintenance.
Fig. 7 is the flow chart of the alternative automatic channel selection scheme of expression.
Fig. 8 is the flow chart of the preferred embodiment of expression automatic channel selection scheme.
Fig. 9 is the performance for the scan table of the usefulness of the automatic channel selection scheme of Fig. 8 that AP keeps.
Figure 10 is the performance for the channel Mapping of the usefulness of the automatic channel selection scheme of Fig. 8 that AP keeps.
Figure 11 is the performance for the tlv triple channel Mapping of the usefulness of the automatic channel selection scheme of Fig. 8 that AP keeps.
Figure 12 is the performance that requires the AP form for the usefulness of the automatic channel selection scheme of Fig. 8 that AP keeps.
Figure 13 is the flow chart how expression AP sets up the known AP form of AP.
Figure 14 is an example of the known AP form of the AP that is used for power adjustments of AP maintenance.
Figure 15 is the flow chart of expression AP foundation for the process of the STA form relevant with AP of the usefulness of load balancing.
Figure 16 is an example of the STA form relevant with AP.
Figure 17 is the block diagram that expression AP regulates the general mechanism of its transmitting power compensation.
Figure 18 is the block diagram of a preferred embodiment of the transmitting power compensation mechanism of expression Figure 13.
Figure 19 is the form of the expression expection standard error relevant with the number of power level sample.
Figure 20 be illustrated in STA and move during, AP regulates the flow chart of the process of its transmitting power compensation.
Figure 21 is the flow chart of AP auction process of the load balancing of the expression STA that is used to cross over AP.
Figure 22 is during expression is auctioned, the flow chart that the request of AP (bid) is handled.
Figure 23 is the flow chart of expression STA initialization procedure.
Figure 24 is the flow chart of the general mechanism of the STA detailed survey channel in the expression wireless communications environment.
Figure 25 is the flow chart that is illustrated in the preferred embodiment of the Figure 20 that realizes in the 802.11 wireless networked environment.
Figure 26 is the example that STA is used for the known AP form of the STA of power adjustments and load balancing.
Figure 27 is the flow chart that expression STA sets up the process of the known AP form of STA.
Figure 28 is the flow chart of expression STA power adjustment procedure.
Figure 29 is the flow chart that expression STA requires process.
Figure 30 is that expression STA calculates the flow chart for the process of the corrected range of the usefulness that determines whether to ask a certain AP.
Figure 31 is the example for the distance_to_rate form that uses in 802.11 wireless networked environment.
Figure 32 is the example for the rate_to_load form that uses in 802.11 wireless networked environment.
Figure 33 represents that in more detail STA requires the flow chart of process.
Figure 34 is the flow chart that expression STA detects its own mobile process.
Figure 35 is the block diagram of the software architecture of expression AP and STA.
Figure 36 is the more more detailed block diagram that realizes the software architecture of AP of the present invention in 802.11 wireless networked environment.
Figure 37 is the more more detailed block diagram that realizes the software architecture of STA of the present invention in 802.11 wireless networked environment.
Figure 38 represents the coding of DRCP (dynamic radio control protocol) message in 802.11 beacon frames.
Figure 39 represents the coding of the DRCP message in 802.11 Frames.
Figure 40 is the form that is summarised in the DRCP message of using in the various aspects of the present invention.
Figure 41 is the form that is described in each field of using in the DRCP message.
Figure 42 is the message format figure of DRCP Preclaim message.
Figure 43 is the message format figure of DRCP Claim message.
Figure 44 is the message format figure of DRCP Announce message.
Figure 45 is the message format figure of DRCP Bid message.
Figure 46 is the message format figure of DRCP Accept message.
Figure 47 is the message format figure of DRCP Registration Request message.
Figure 48 is the message format figure of DRCP Registration Acknowledge message.
Figure 49 is from the viewpoint of wireless network user, and expression is along with the discrete measurement of the received power in the past of time.
Figure 50 is from the viewpoint of wireless network user, and expression is along with the discrete measurement of the received power in the past of time, and is illustrated in 99% the confidential interval, for the mean receiving power of user's estimation.
Figure 51 is similar to Fig. 3, and expression is for two of less sample-size different measurement of estimation mean receiving powers and their 99% confidential intervals.
Figure 52 represents that two different estimation mean receiving powers are measured and their 99% confidential interval, and one is used for bigger sample-size, and one is used for less sample-size.
Figure 53 represents to have a long-term average measurement and a short-term averaging of 99% confidential interval and measures, and this shows that relatively can to determine the user mobile.
Figure 54 is that expression converges on zero in order to make long-term average confidence interval scope, the form of the number of the sample that need adopt.
Figure 55 is the flow chart of the general operation of expression method of the present invention.
Figure 56 is a block diagram of wherein disposing an embodiment of wireless network of the present invention, and wherein AP determines that a certain user is mobile.
Figure 57 is the block diagram of an alternative of the present invention, and wherein the user determines that this user is mobile.
Figure 58 is the block diagram that adopts one embodiment of the present of invention of circular buffer.
Figure 59 adopts the block diagram of an alternative of the present invention of device in batch.
Embodiment
According to the present invention, for wireless communications environment provides a kind of full-automatic control system.Referring to Fig. 1, typical wireless communications environment 10 comprises and being connected between wire communication medium 14 and the wireless device 16, and the access device 12 (shown in the figure one) of network insertion is provided to wireless device 16.Thereby wireless device 16 can and intercom with wireline equipment 18 communications mutually by access device 12.These access device 12 usefulness depend on that the different titles of the wireless architecture that is adopted represent, are called as " access point " or " AP " here.Wireless device 16 also has the various titles relevant with architecture, is called as " station " or STA here.The equipment that can realize radio communication can be AP or STA, perhaps the two.
There are various types of wireless communications environments 10.Wireless communications environment for example comprises radio data network and wireless I/O channel. has described an example of radio data network in " IEEE Standard for Information technology-Telecommunications and information exchange between systems-Localand metropolitan area networks-Specific requirements-Part 11:WirelessLAN Medium Access Control (MAC) and Physical Layer (PHY) specifications-Amendment 1:High-speed Physical Layer in the 5GHZband ", the document is drawn for reference to (below be called 802.11) at this. In addition, various 802.11 " patterns " have been defined.For example, in the wireless network of compatible IEEE 802.11, wireless device can be arranged in " infrastructure mode ", thereby network is configured to so that STA 16 communicates by letter with other network equipment by AP 12, as shown in fig. 1.Compatible 802.11 equipment also can be arranged in " ad-hoc (self-organizing) " pattern, thus all STA 16 in transmitting boundary, and each other can direct communication.In addition, have wireless " grid " technology, thereby each wireless device not only serves as AP but also serve as STA.Wireless I/O channel can be used for providing the I/O between server and the memory device communication by " bluetooth " standard, and the I/O between the home entertainment Voice ﹠ Video assembly perhaps is provided communication, and the I/O between radio telephone and the base station perhaps is provided communication.Various aspects of the present invention generally are applicable to wireless networking architecture, are included in the wireless networking architecture of using in wide area network, metropolitan area network, enterprise network and the home network, and wireless I/O channel architectures existing and development.
According to various aspects of the present invention, the WAP (wireless access point) of arbitrary number (AP) can be disposed in the optional position, and all AP and STA will dispose they oneself automatically, links so that realize best channel use, power level and STA/AP.Thereby in wireless networked environment, channel uses optimised, and the interference between the AP simultaneously is minimized.Wireless device such as having the on knee of wireless capability or hand-hold type computing equipment or IP phone machine be by transparent and seamlessly be distributed between the AP, so that from the user's of wireless device viewpoint, network performance is optimised.In addition, in the wireless I/O channel circumstance that may adopt in the family, audio frequency, video and miscellaneous equipment are moved, and nonexistence can worsen, and the use of the channel of each equipment can be optimised, so that equipment can the phase mutual interference.
In order to promote understanding of the present invention, below description is applicable to some examples of known 802.11 wireless lan architectures, condition is that principle of the present invention is applicable to any wireless communications environment more at large.So a preferred realization of the principle of the invention will be described as and be embodied in 802.11 wireless networks.
Its advantage is facilitated in following aspect of the present invention, will describe each aspect in detail below:
1.AP initialization: in many wireless communications environments, a plurality of frequencies (" channel ") can be used for AP.For example, according to 802.11b and 802.11g, there are three non-overlapped channels to use.According to IEEE 802.11a, there are 13 non-overlapped channels to use.In adopting the environment of a plurality of AP,, advantageously use different channels to optimize performance and make minimum interference for AP.According to the present invention, AP carries out automatic channel and selects.Under a plurality of AP were distributed in situation in the appointed area, AP carried out distributed protocol, so that select channel for each AP.AP located adjacent one another uses non-overlapped channel.
1.AP optimize:
A. power adjustments: when the AP in the wireless communications environment outnumber the number of non-overlapped channel the time, AP and STA regulate their power, so that the AP on the same channel and STA can co-exist in a certain zone by interference-free.For the AP that uses same channel, AP is according to environmental factor, such as the power level that is readjusted them by the mobile change in signal strength that causes of door, people, background noise minimum etc., thereby user's optimum bandwidth is held, and does not have undue disturbance.
A. auction: AP monitors the various parameters of the STA that links with them all the time, and for the purpose of load balancing, STA will roam between AP, and this can help to make the best performanceization in one group of STA.
1.STA initialization: STA and initial AP link.The STA that invention enables opens the function that the AP that allows them to enable from invention receives message.
1.STA optimize:
A. channel detailed survey: in order further to optimize performance, whether other channel in the frequency band that the regular detailed survey STA of STA works just therein exists " better " AP so that understand.In order to determine another AP whether " better ", consider various parameters, such as signal strength signal intensity and load factor, the back will further specify this.
A. request: if find better AP, STA enters request process so, to attempt making this STA roam into this better AP.Thereby realization load balancing.In addition, by moving at STA after more approaching this better AP, this STA and better AP are linked, request process adapts to STA and moves.
A. power adjustments: STA carries out power adjustments, so that they can keep being to and from their throughputs of relevant AP at present, makes simultaneously and may use the interference of the contiguous wireless device of same channel to reduce to minimum.
A. move to detect: STA moves detections, and consequently when STA was mobile, request process can be closed, and stops to restart when mobile as STA subsequently.When restarting, can find " better " AP, thereby STA will ask to it.
1. software architecture
A. the most handy modular manner is realized above-mentioned functions in AP and STA, so that the transfer between platform is easy.
A. illustrate in greater detail the realization of above-mentioned functions in preferred 802.11 network environments.
1. mobile detection statistics analysis: describe a kind of pin-point accuracy and calculating and detect new departure that attribute changes because of the influence that is subjected to the strong noise variation effectively, this scheme is used to detect moving of wireless STA.
Because the example of example will be referred to 802.11 networked environment, therefore the information below provides related context, but can understand the present invention is not confined to 802.11 environment.
In 802.11 networks, AP regularly sends the frame that is called " beacon ".STA monitors beacon.When hearing beacon under irrelevant STA (that is, the STA that can't communicate by letter on the wireless network) is thinking rational power level, it can be attempted verifying the AP that sends described beacon, and link with this AP subsequently.In case checking and link after, STA just can pass through described AP, other STA transmission Frame on wireless network.
More particularly, AP and STA send and respond three kinds of dissimilar frames, are called 1 class frame, 2 class frames and 3 class frames.Whether whether 1 class frame comprises control frame and management frames, can be verified and be sent out with AP with linking regardless of STA.Beacon is a kind of 1 class frame.2 class frames have only when STA is verified and just are sent out, and comprise the requirement/response message that for example links.3 class frames have only the Shi Caineng that ought be linked to be sent out, and comprise Frame.
In order to make the maximization of user bandwidth and throughput, the present invention is the operation of a plurality of AP of wireless communications environment Automatic Optimal of appointment.According to the IEEE 802.11a networking standard of example, 13 non-overlapped frequencies can be used for AP.Each AP can transmit and receive data with the maximum rate of maximum 54Mbps.The actual speed rate that transmits and receives data between AP and STA depends on many factors, comprises the distance between AP and the STA, building between AP and STA and the environmental interference that occurs on characteristic frequency.Those skilled in the art will recognize that the present invention is not limited by the maximum data rate of current wireless technology, is not subjected to the rf attenuation effects limit of current understanding yet.Along with the development of wireless technology, principle of the present invention continues to be suitable for.
The zone of consideration wireless network as shown in Figure 2 and so on wherein can be the shared upward space of the single AP 12 of work of one of 13 available 802.11a frequencies (being expressed as f1) that is included in of 8 users (being expressed as STA 16) of mobile laptop computer, PDA etc.The bandwidth that these 8 users, 16 sharing A P 12 provide.If all 8 users 16 are enough approaching with AP, so that AP provides 54Mb bit maximum data rate, all 8 users 16 share the bandwidth of AP so, so that each user on average keeps the throughput of 6.75Mb, and (the present invention imagines data traffic and happens suddenly, and the user in this example can obtain the throughput of 54Mb in the short time interval, but for for simplicity, the average throughput along with the time of designated user is discussed).
Referring now to Fig. 3,, in this zone, added the 2nd AP 12.The 2nd AP 12 to be in one of 13 frequencies (being expressed as f2) work of going up, so that these two AP do not disturb, and their relevant STA 16 does not disturb yet.As shown in the figure, 4 among 8 users have roamed into the 2nd AP 12.Each user on average keeps the throughput of 13.5Mb now.On different frequencies, add other AP and further increased the average throughput of user.
According to the present invention, dynamic radio control protocol (DRCP) provides a kind of wireless frequency and power of controlling them automatically for any a collection of STA and AP, so that the characteristic of example in the expander graphs 2, thereby makes the mechanism of whole system maximizing performance.DRCP message and is transmitted between AP and STA between AP and AP, so that realize this function.Use 8 kinds of message: DRCPPreclaim, DRCP Claim, DRCP Announce, DRCP Bid, DRCP Accept, DRCPRegistration Request and DRCP Registration Acknowledge.
DRCP Preclaim and Claim message exchange between AP during the AP initialization, and are used to help to select according to automatic channel of the present invention.DRCP Announce message is sent and is received by STA by AP during STA optimizes.The STA that the AP that available the present invention that these Announce message can be selected them to link with it enables notifies the present invention to enable, and information about AP is provided, STA can use described information to help decision and whether require to roam into another AP.DRCP Bid message sends to AP by STA during STA optimizes.The AP that the STA that these message enable the present invention who requires to link with AP notifies the present invention to enable.Response DRCP Bid message, DRCP Accept message sends to STA by AP.These message informings STA, it can require the AP that links to link with it.The DRCP registration requires and acknowledge message is enabled by the present invention AP and STA exchange are so that point out that to each side the opposing party has the DRCP ability.
Adopting the DRCP agreement of these message at first to be described as is used in the general wireless communications environment.To utilize the preferred embodiment in 802.11 environment subsequently, further specify each the detailed realization in these message.
To illustrate that now various aspects of the present invention are applied to AP initialization and optimization, be applied to the situation of STA initialization and optimization subsequently.Notice that when realizing the of the present invention many aspects about STA and AP description are favourable here, but they are not required to realize in wireless communications environment.When having only AP, perhaps have only STA, when perhaps AP and STA realize one or more aspect in the various aspects of the present invention, can the obtained performance advantage.
1.
The AP initialization
During the AP initialization, AP carries out automatic channel and selects.According to channel selection of the present invention aspect, the AP that is arranged in same wireless network automatically selects the channel that is used to operate, so that near their AP not disturbing.It is available that the present invention imagines different frequency bands, for example based on 802.11 versions and the country that disposes this network.According to a preferred embodiment, AP attempts to select the channel that least may disturb other AP that has disposed in each working band that is equipped with AP.AP also isolates channel according to the rule relevant with control zone (Europe etc.), thereby they can not disturb other wireless application (radar etc.).Select a free channel at AP, and another AP selects simultaneously under the situation of identical free channel (being that channel is selected " conflict "), medium access control (MAC) address of AP is used as tie breaker.If described another AP does not comprise improved standard A P related to the present invention, the AP that enables of the present invention will point to " next the best " channel to its radio so.AP is to each frequency band interactive channel choice phase.
More particularly, referring to Fig. 4, in initiate AP 12 beginnings " beacon on " (promptly, to other AP and STA broadcast control grouping) before, this AP 12 at first checks the RF list of frequency bands that AP 12 supports, with each RF frequency band, realize that the radio of physical layer (PHY) is supported but not segregate channel list.AP 12 selects a channel in each frequency band according to following algorithm subsequently:
For each frequency band:
Sweep spacing regularly produces.During sweep spacing (step 20), all channels (step 22) that AP supports in this frequency band of AP 12 drive sweeps.AP 12 collects effective AP 12, the channel that they are being worked and hear the tabulation of the power of beacon from each AP 12.This information is used to set up the form (step 26) that is called channel Mapping 24, and described channel Mapping comprises all AP 12 that hear thus, the tabulation of the signal strength signal intensity that channel that AP 12 is heard and AP 12 are heard.For each frequency band, there is an independently channel Mapping 24.12 pairs of channel Mapping classification of AP are to produce the tabulation (step 28) of AP 12 according to the ascending order of power level.
Referring to Fig. 5, AP 12 present following selective channels.At first, AP 12 reads channel Mapping (step 30) in detail, if deposit the channel (that is, signal strength signal intensity=0) (step 32) of working without any AP 12 thereon, AP 12 selects these channels (step 34) so.Otherwise AP 12 reads this tabulation in detail, launches the channel (step 36) of weak signal with searching.AP 12 enters the time interval (step 38) that is called " requiring (claiming) cycle " now.
If AP 12 selects to have the channel of weak signal strength, AP 12 notes the channel id of the channel that its selects so, the received power level on this channel and produce the AP-ID (step 40) of the AP of this power level.It will use this power level value, and it detects the benchmark of the increase of the received power on the channel that its selects in contrast.If AP 12 has selected a vacant channels, the reference power level will be the noise floor of AP so.
AP 12 is subsequently by requiring in the cycle periodic transmission DRCP Claim message, the intention (step 42) of its use selected channel of advertisement.With full power emission Claim message.In this requires the cycle, AP 12 is received in all beacons (Beacon) that transmit on the channel of current selection, DRCP Claim message and DRCP Announce message (step 44), and use the information that wherein comprises to set up " Other Aps " form 46 (Fig. 6, Fig. 5, step 48).For each beacon that it is received, AP 12 is recorded in AP-ID in the Other Aps form 46 with the power level that receives.For each Claim or the Announce message that it is received, AP 12 is the AP-ID of the AP that sends this message, and power level that receives and transmitting power compensation (TP compensation) are recorded in the OtherAps form 46.How far the radio of TP offset indication transmission AP has been attenuated to from maximum power has, and will illustrate in greater detail in AP power adjustments part.AP 12 also is labeled as the clauses and subclauses that are used for this AP-ID has the DRCP ability.By the TP offset being joined in the power level of reception the normalized received power value.The balanced AP power level of standardization received power value is so that comparison.When the AP that has had clauses and subclauses from it as AP 12 received beacon or DRCP message, it upgraded this clauses and subclauses, and the power and the TP_backoff value that receive are saved as tabulation.
If another AP 12 beginnings sizable energy of emission on the channel of selecting, inevitable one of the two kinds of incident that taken place.New AP 12 or do not move DRCP has perhaps produced with the effective AP of another DRCP-and has conflicted, and here, race condition has caused the effective AP of another DRCP-to select identical channel simultaneously.This is called as channel and selects conflict (CSC).
When requiring end cycle (step 50), AP 12 stops to send Claim message, and assesses the information that it is collected, and its CSC data are to determine whether to have taken place CSC.It checks whether the received power in any clauses and subclauses is the reference power level (step 52) of this channel record greater than it.If it checks whether received power is exceeded (step 54) in half the power level value at least of these clauses and subclauses so.If AP 12 checks whether the AP in these clauses and subclauses has DRCP ability (step S56) so.
If another AP is not that DRCP is effective, AP 12 defers to the effective AP of this non-DRCP so, and starts whole channel selection procedure once more.
If it is effective that another AP is DRCP, think so CSC takes place.When CSC takes place, compare the MAC Address of another AP and the MAC Address of this AP 12.If the MAC Address of this AP 12 is in number greater than observed MAC Address (step 58), this AP 12 starts this channel selection procedure at this so.
If when requiring end cycle, AP successfully requires selected channel, and it begins to move on this channel so.AP begins to send beacon, begins to send DRCP Announce message, and prepares to enter the optimizing phase, so that move its auction and power adjustments function (step 60).
When several AP 12 were switched on suddenly, a kind of modification of the channel selection procedure of Fig. 5 can be used to improve channel and select coverage rate.Referring to Fig. 7, when energising, each AP is being selected from first channel of channel Mapping ... for example on the channel appointed 1, send Claim message (step 62,64).All AP scan all channels.All AP of scanning will receive Claim message each other on channel 1.Requiring in the cycle, AP will determine whether channel 1 in fact can be for its use.Therefore, this AP monitors other DRCP Claim message on the same channel, and the AP that described other DRCPClaim message will indicate another the present invention to enable is attempting to use identical channel (step 66).This AP follows the tracks of the number (according to the AP ID of the Claim message of receiving) of the different AP that it hears and all the time from the average signal strength of the Claim message of each AP.This AP sets up adjacency vector (adjacent count, in abutting connection with gross power) (step 68).The number of the AP that the adjacent count representative is heard on this channel.Represent the summation of the average power level of each AP that hears in abutting connection with gross power.Each AP sends to all other AP (step 70) in its Claim message to its adjacent vectors.If receive DRCP Claim message (step 72), in the case on channel 1, this AP 12 is at first with its contiguous counting and contiguous count compare (step of receiving in Claim message 74) so.If the contiguous counting of this AP 12 is higher than the contiguous counting of receiving in Claim message, this may indicate the central authorities that this AP 12 more approaches network so.So this AP 12 continues requiring to require this channel in the cycle.If the contiguous counting of this AP and the contiguous counting of in Claim message, receiving identical (step 76), so this AP 12 subsequently relatively its contiguous gross power and in Claim message, receive in abutting connection with total power value.If the contiguous gross power of AP 12 oneself greater than in Claim message, receive in abutting connection with total power value (step 78), this also may indicate the center that this AP 12 more approaches network so, so this AP 12 continues to send the Claim message about this channel.If the contiguous gross power of AP 12 oneself with receive in abutting connection with total power value identical (step 80), AP 12 carries out aforesaid MAC Address test (step 82) so.If AP 12 finds its adjacent counts or in abutting connection with power less than any adjacent count of in Claim message, receiving or in abutting connection with power, perhaps its MAC value is bigger under the situation that these values equate, it stops to send the Claim message about this channel so, and returns and read channel Mapping (step 84) in detail.Otherwise AP 12 continues to send the Claim message (step 70) that comprises its adjacency vector.If when requiring end cycle (step 86), the adjacency of AP 12 is greater than the adjacency of other AP, and this AP 12 has won this channel so, and forwards AP optimizing phase (step 88) to.According to this method, the AP that approaches the center of many AP network most obtains first channel allocation, and subsequent communication channel is assigned to other AP.
Referring to Fig. 8, there is shown a preferred embodiment of automatic channel selection algorithm.For each frequency band:
Regularly produce sweep spacing.In sweep spacing (step 100), all channels that AP supports in AP 12 these frequency bands of scanning receive beacon and Announce message (step 102).The information that receives in beacon and Announce message is used to set up the form (step 104) that is called " scan table ".An example of scan table 106 has been shown among Fig. 9.Scan table 106 comprises clauses and subclauses receiving each AP of beacon or Announce message from it.For each clauses and subclauses, preserve AP-ID and the channel of hearing AP 12.Preserve " rxPowerRunningTotal " value of summation of the signal strength signal intensity of each message that expression receives from AP 12 in addition.Preserve " rxPowerSampleCount " value of the number of the message that expression receives from AP 12 in addition.If received Announce message, the DRCP sign is set so from AP 12.When each channel was scanned, the entryAge clauses and subclauses were incremented.Calculate " rxPowerAvg " in the Preclaim interval, the back will further specify this.
Along with the carrying out of scanning, the rxPowerSampleCount value in the scan table 106 is monitored, if any one in them surpassed threshold value (being labeled as " threshold value 1 " here) (step 108), AP 12 enters step 110 to set up channel Mapping so.In addition, if any entryAge value in the table surpasses a certain threshold value " threshold value 2 " (step 112), AP 12 will enter step 110 so.In addition, if the number of times of the scanning of finishing surpasses a certain threshold value " threshold value 3 " (step 114), AP 12 will enter step 110 so.Otherwise AP 12 continues scanning and upgrades scan table 106.
An example of preferred channel Mapping 116 has been shown among Figure 10.Channel Mapping 116 comprises clauses and subclauses about each channel id.In order to set up channel Mapping, AP 12 reads scan table 106 in detail, and " rxPowerAvg " value of each clauses and subclauses is calculated as:
RxPowerAvg[I]＝Scan table[i].rxPowerRunningTotal /Scantable[i]rxPowerSamplecount；
For each channel, the AP-ID with the highest rxPowerAvg value is transfused in this channel Mapping 116.The rxPowerAvg value of this AP is transfused in the channel Mapping 116, as the highestPwrlevel parameter.
In some networks are realized, do not wish in certain distance each other, to exist the AP 12 in two work, network performance can be do not improved because do so, and network performance can be reduced.Thereby according to a kind of preferred selection, in case channel Mapping is collected, AP 12 just checks channel Mapping so, to check whether there is the highestPwrlevel value (step 118) that surpasses a certain power level threshold in channel Mapping.Select power level threshold with the position of indication AP 12 too near another AP.If highestPwrlevel surpasses power level threshold arbitrarily, this AP 12 is placed in " standby mode " (step 120) so.Before turning back to another sweep spacing of beginning, the AP 12 under the standby mode waits for a period of time that is called " standby interval " here.
Do not surpass power level threshold if find any highestPwrlevel value, AP hand assemble tlv triple channel Mapping 124 (steps 126) so.As shown in Figure 11, AP 12 is categorized into triplets to channel Mapping, and for example channel 1,2 and 3, channel 2,3 and 4, channel 3,4 and 5 etc.The power of receiving on each channel in tlv triple is asked average out to tlv triple mean value.According to the list category of ascending order to tlv triple, the tlv triple that average power is minimum is positioned at the top of tabulation.AP 12 is from the top of this tabulation, and searching wherein is less than or equal to first tlv triple of the power of receiving on two adjacent channels at the power of receiving on the central channel of tlv triple, and select this channel (step 128).If there is no such tlv triple, AP selects to have the channel of minimum tlv triple mean value so.In the example shown in Figure 11, AP 12 selective channels 3.By selecting not have the channel that the high power adjacent channel uses, this process advantageously makes the interference of interchannel reduce to minimum.
In some network environments, particularly in the environment that is limited in scope, the work of too much AP can not improve network performance on the same channel, and can cause performance to reduce.Thereby according to a kind of preferred selection, AP checks whether exist in the too much AP (step 142) that works on the network.The number that is present in the different AP-ID in the Preclaim Aps table is used to finish this definite.If under power level greater than the threshold value that defines, too much AP work is arranged on selected channel, AP12 enters standby mode so.
The too much AP that if there is no works on selected channel, AP 12 calculates " adjacency vector and " (step 146) so.To all AP on all channels calculate adjacency vectors and:
Adjacency vector and=sum (Preclaim APs[i] .ReceivedPowerTotal/PreclaimAPs[i] .count)
At Claiming in the time interval, if desired, adjacency vector and be used as moderator, the back will further specify this.
AP 12 assesses Claim Aps table 154 (step 160) subsequently, to determine whether to hear any other AP.If do not have any clauses and subclauses (step 162) in Claim Aps table 154, AP 12 wins selected channel so.AP 12 begins to send beacon subsequently, and sends the Announce message (step 164) about this channel.If Claim Aps table 154 comprises one or more clauses and subclauses, if so when the Claiming time interval begins, selected channel is empty (step 166), and AP 12 abandons this channel so, and returns and rescan (step 100).Otherwise, if channel is not empty, if so in the table ReceivedPowerlevel value of all clauses and subclauses less than the reference level that during Preclaiming, writes down adding threshold level (for example, 2db) (step 168), this AP wins this channel (step 164) so.But, if AP finds to surpass the ReceivedPowerlevel value that the reference power level adds threshold level, and these clauses and subclauses be not at Preclaiming in the time interval, the AP-ID that writes down on this channel is relevant, AP checks the DRCP sign (step 170) of these clauses and subclauses so.If the DRCP sign indication AP-ID relevant with these clauses and subclauses do not have the DRCP ability, this AP returns trace interval so, to restart channel selection procedure.If the DRCP sign indication AP-ID relevant with these clauses and subclauses has the DRCP ability, AP compares its adjacency vector and the adjacency vector (step 172) that receives in the Claim of another AP message so.If the adjacency vector of this AP is less than the adjacency vector of another AP, this AP abandons this channel so, and returns and rescan.If the adjacency vector of this AP is not less than the adjacency vector of another AP, this AP checks whether adjacency vector equates (step 174) so.If equate, compare the MAC Address (step 176) of these two AP so.If the MAC Address of this AP is greater than the MAC Address of another AP, this AP wins this channel (step 164) so.Otherwise this AP abandons this channel, and returns and rescan (step 100).Those skilled in the art will recognize that it is arbitrarily that MAC Address is relatively made a strategic decision, and can carry out according to opposite mode.
1.
AP optimizes
In case AP just moves on a certain channel, it just carries out following function continuously, so that its configuration in the optimization WLAN:
Wireless power is regulated.The AP that each DRCP enables regulates its power rightly, so that adapt to the nearest AP work on its channel, keeps it and the connection of its relevant STA farthest simultaneously.AP passes on the TP_backoff parameter in its Announce message.The TP_backoff value provides and sends the indication what degree AP has been reduced to its transmitting radio.This TP_backoff value is used for determining their TP_backoff value by other AP.A STA relevant with this AP can adopt the TP_backoff value of transmission to regulate its wireless power subsequently, and when this value changes, can follow the trail of this value.
Auction.AP manages auction process, so that according to the DRCP Bid message that receives, accept new DRCP STA rightly and be used to link.Utilize preferred embodiment that this two kinds of functions are described now.
2.a wireless power is regulated
2.a.1 the form that AP keeps
Regulate in order to carry out wireless power, AP 12 keeps a plurality of forms.These forms comprise from the information of other AP that works at selected channel and STA reception.This information is used to definite power level such as the miscellaneous equipment on this channel, and the thing of distance between the equipment on this channel and so on is so that the power level of control AP.
2.a.1.1AP known APs table
Each AP 12 keeps a plurality of forms, it with reference to these forms to carry out power adjustments.Such form is the known APs table 200 of AP.As shown in Figure 13, in case be initialised on a certain channel, AP 12 receives beacon and DRCP Announce message (step 202,204,206) from all other AP 12 that work in its a-n radio range a-n on its channel.AP 12 uses the message of these receptions to set up the known APs table 200 of AP.For each message that it is received, AP 12 checks whether it has the clauses and subclauses (step 208) about the AP-ID in this message in the known APs of AP shows.If finding has, AP 12 upgrades these clauses and subclauses (step 210) so.Otherwise it creates new clauses and subclauses (step 212), can reach Max_Ap clauses and subclauses (step 214) at most.The value of Max_AP depends on design.
Referring to Figure 14, AP 12 is kept at following field in known APs table 200 clauses and subclauses of corresponding AP:
·AP-ID
TP Backoff (compensation)
Maximum power
The DRCP ability
Age
Standardization power
Sample size
Corrected output
AP-ID, TP compensation and maximum power field extract from each the DRCP Announce and the Hello message that receive.The TP offset is saved a value list into each message that receives from each AP-ID.Sample size is the number about the TP offset of each AP-ID reception.
Because Announce message is only sent by the AP that DRCP enables, thus AP 12 also these clauses and subclauses to be labeled as DRCP effective.It is effective that the AP that sends the beacon do not comprise the DRCP field is not marked as DRCP.For each message that receives, AP adds the TP offset in the power level that receives, so that the received power level of following settling the standard:
normalized_power＝avg(received_power+tp_backoff)
Taking into account TP compensation in the standardization power level provides consistent and can be used to and measurement of power levels result numerical value relatively from other AP.
The beacon that receives also has the TP offset ambiguously, still owing to always under full power, launch beacon, thus they in fact to have be 0 TP offset.Thereby AP 12 can upgrade the known APs table 200 of AP according to the beacon that receives.In this case, AP 12 saves as 0 to the TP offset, and the power level value that standardization power and maximum power are configured to receive.
In addition, AP 12 preserves the age of each clauses and subclauses.At every turn when the AP corresponding to these clauses and subclauses received beacon or DRCP Announce, it was 0 that the age is reset.As the part of AP power adjustment procedure, clauses and subclauses are by aging.
2.a.1.2 the STAs relevant table with AP
The form of the STA 16 that the also continuous maintenance of AP 12 the is associated-STAs table relevant with AP.Referring to Figure 15, for each relevant STA 16, AP 12 monitors and collects the signal strength information (step 220) of the packet that receives.If there have been the clauses and subclauses (step 222) of this STA in the STAs table relevant with AP, these clauses and subclauses are updated (step 224) so.Otherwise for this STA creates new clauses and subclauses (step 226).The data that the AP periodic analysis is collected are so that carry out the AP power adjustments.In addition, whenever the effective STA 16 of DRCP becomes when being associated with AP 12, it just sends Registration Request message to this AP 12.STA 16 regularly sends Registration Request message to AP 12, till STA 16 receives RegistrationAcknowledge message.When STA 16 receives Registration Request (step 228), AP 12 upgrades the clauses and subclauses in the relevant STA table, it is labeled as the effective STA of DRCP (step 230), and Registration Acknowledge message is sent to STA 16 (step 232).
As shown in Figure 16, the STA table 240 relevant with AP of AP 12 keeps the following information about each STA:
The MAC Address of the STA-ID--station
The value of the time quantum of Quiet-time-expression since receiving data from this STA at last
DRCP-Active-be defaulted as vacation is true when receiving Registration Request
Distance-, calculate according to signal strength information and TP compensation to the distance (with Banzais is unit, will further specify) of this STA
The tabulation of maximum power-performance number
The number of the power sample of power sample-reception
·Normalized_power
·Corrected_power
Sta_load_factor-the load of this STA on this AP saves referring to 4.c.
2.a.1.3AP power adjustments
In channel selection procedure, AP12 launches with maximum power, that is, its use is 0 TP offset.In case AP 12 successfully requires a certain channel, it just calculates the TP offset, and it is used for the transmitting power of transfer of data according to the adjusting downwards of this value, so that the same channel minimum interference, and make channel/bandwidth reuse maximization.Further specify the calculating of TP offset now.
In general, with reference to Figure 17, the AP of finishing power adjustments as described below: AP 12 reads the known APs table (step 260) of its AP in detail.AP 12 searches the AP that has the highest TP offset in this form.AP 12 is arranged to the highest TP offset (step 262) to its maximum TP offset subsequently.If maximum TP offset is used as the TP offset of AP 12, it will just be reduced to the transmitting power of AP 12 and be lower than under the scope of the nearest AP that works on the same channel so.
In case calculated maximum TP compensation, AP scans relevant STA table subsequently, to be determined to the distance (step 264) of relevant STA 16 farthest.Relatively to the distance of farthest relevant STA 16 with to the distance (step 266) of the nearest AP 12 that on same channel, works.If the distance that arrives relevant STA 16 farthest is less than the distance to nearest AP 12, the TP compensation values maintain of AP compensates (step 268) at maximum TP so.If to the distance of farthest relevant STA greater than distance (step 266) to the nearest AP that on same channel, works, so again regulate maximum TP offset downwards, so that adapt to this STA (step 270), and the TP offset of AP is arranged to value (step 272) after this adjusting.Regularly repeat this power adjustments, so that the variation (step 274) in considering the known APs table of AP and the STAs relevant with AP showing.For example in 802.11 environment, but per second repeats power adjustments.
According to for the preferred embodiment that in the wireless data networked environment, uses, as shown in Figure 18, the above-mentioned power adjustments of AP execution as described below.At first, AP 12 checks whether its Avoid Other WLAN sign is set up (step 280).Avoid Other WLAN sign is the configuration parameter that can influence power adjustments.In many wireless networking architectures, in the different physical network of service, several AP may occupy identical channel.For example, in 802.11 architectures, several AP can serve different ESS.Avoid Other WLAN sign is defaulted as vacation.When being set to fictitious time, AP 12 will ignore its physical network any other AP different with the physical network (for example ESSID) of this AP 12 on the same channel.This selection is used in the situation of the quite near a plurality of AP of existence on the different networks.In this case, operator would rather move its AP with maximal power level, so that the possible signal of the best is provided for all stations on its network.
If Avoid Other WLAN sign is not set up, AP 12 its TP compensation are set to 0 (step 282) so.So as long as Avoid Other WLAN sign is not set up, AP12 just will launch with full power.If Avoid Other WLAN sign is set up, AP proceeds power adjustment procedure so, and will can not disturb other AP, even they are worked on different networks.
Each hello time interval, AP 12 handles the information (step 284) in the known APs table of AP, so that carry out power adjustments.Hello time depends on architecture and design at interval.In 802.11 environment, hello time at interval can be 100ms beacon time interval for example.Before carrying out other processing, the KnownAPs table clause is at first aging.The age of each clauses and subclauses is incremented (step 286), and deletes any clauses and subclauses (step 288,290) of its age above the maximum AP clauses and subclauses age.Thereby if a certain AP also is not heard after a while, it is influenced the power adjustments calculating of this AP 12 by aging and deletion from table to prevent it so.
As previously mentioned, average, determine the standardization power field of the clauses and subclauses " n " of the APs table that AP is known by power measurement sample to several receptions.The number of sample that is used to draw this value is big more, and it is accurate more to measure.As shown in following formula, by deduct the standard error based on sample size from the standardization power level, AP has considered the inaccuracy of this value.Attention is in 802.11 environment, and the standardization power level is contemplated to negative, and number range is from-25 to-90dBm.The APs[n that AP is known] .corrected_power=AP is known
APs[n].normalized_power-
getStandardError(sample_size)；
In this formula, function " getStandardError " can return the standard error of the sample-size " sample_size " in each clauses and subclauses " n ".For example, the Table I among Figure 19 illustrates the standard error value of a plurality of sample-size of RF signal measurement.This formula is applied to each project " n " in the known APs table of AP, so that calculate the corrected_power value (step 292) of each clauses and subclauses.
The AP table that scan A P is known subsequently is to seek and the corresponding clauses and subclauses of hearing under the highest corrected_power level of AP.The noise floor (step 294) of this corrected_power level and AP 12 relatively.(noise floor of AP is the measuring of background power on the channel).If AP 12 finds the noise floor of the highest corrected_power level less than AP 12, AP 12 can maximum power transmission so, and other AP on can interference channel.So it is its maximum TP compensation values maintain 0 (step 296).But if AP 12 finds the noise floor of the highest corrected_power level greater than AP 12, it need be provided with the TP compensation so, to avoid interference that AP.In this case, AP 12 calculates maximum TP compensation (step 298) by deduct its noise floor from the corrected_power relevant with that AP.
In case calculated maximum TP compensation, AP 12 must determine whether to exist more any relevant STA 16 away from (be its signal strength signal intensity less than) highest_power_AP subsequently.Analyze the relevant STAs table of AP 12, so that find out the STA 16 (step 300) apart from maximum with AP.The normalized_power of this STA and sample-size value are used to calculate as previously mentioned the corrected_power value of this STA.Compare the corrected_power level of lowest power STA and the noise floor (step 302) of AP 12.If the corrected_power level is less than described noise floor, AP 12 need move under full power covering this STA so, thereby the APTP offset is set to 0 (step 304).If the corrected_power level is greater than the noise floor of AP 12, STA TP offset is configured to the corrected_power level and deducts noise floor (step 306) so.
Subsequently, more maximum TP compensation and STA TP compensation (step 308).The TP of AP compensation (" my TP compensation ") is set to the smaller in these two offsets, to avoid interference nearest AP, guarantees the covering to farthest STA simultaneously.Thereby if STA TP compensation compensates less than maximum TP, my TP compensation is configured to maximum TP offset (step 310) so.If STA TP compensation is greater than maximum TP compensation, my TP offset is configured to STA TP offset and adds a certain minimum signal to noise ratio (step 312) so.
In addition, various wireless networking architecture can provide the mechanism of removing wireless channel, further increases the possibility of receiving administrative messag.For example, in 802.11 architectures, AP sends Clear to Send (CTS) (clear to send) message, so that remove channel (step 316), sends DRCP Announce message (step 318) with maximum power subsequently.After sending Announce message with maximal power level, AP recovers the TP offset of its calculating is used for packet, reduces to minimum so that same channel disturbs, as mentioned above.
The AP power adjustments during 2.a.1.3.i the station moves
When STA 16 and AP 12 linked, AP 12 followed the tracks of the distance between STA 16 and the AP 12 all the time.If AP 12 is using non-0 TP offset, and AP 12 determines that STA 16 just are moved to outside the scope of AP 12 at compensation power, and AP 12 can regulate its TP offset so, to adapt to moving of STA 16.
With " Banzais " is that unit calculates the distance between AP 12 and the relevant STA 16, and it is kept in the relevant STAs table.Banzai is that always comfortable known transmitting power compensates time unit of the distance that the measurement result of the received signal intensity of the AP 12 of work obtains.For example, in 802.11 environment, the signal strength measurement of reception is general estimate from-25dBm～-number range of 90dBm, but depend on that scope is from 0dBm to-100dBm in high-end possible antenna gain or in the sensitivity of low side.The transmitting power compensation is general to be estimated to change in the number range from 0dB to 65dB.Given received signal strength measurement result " received_power " and transmitting power compensation " TP Backoff " from AP, the so following distance (is unit with Banzais) that calculates this AP:
distance_in_banzais＝ABS[MIN[0，(received_power+tpbackoff)]]
The back illustrates in greater detail moves the algorithm that detects.For the AP power adjustments, as previously mentioned, along with the past of time, AP 12 collects a plurality of samples and the TP offset of the received_power of each STA 16, and in the distance of calculating on all these samples between AP and the STA.AP 12 by check continuously from group leader's phase sample obtain to the difference the distance of each station whether enough less than current distance measurement result based on the sample of nearest collection, STA16 detects mobile away from its AP 12 with indication.
If AP 12 detects STA 16 and is leaving, and STA 16 is (compensating based on current TP) in the appointment short-term standard error Banzais scope of leading edge of transmitting, to be transformed into be 0 TP compensation to AP 12 so, till it no longer has associated any mobile STA.
More particularly, referring to Figure 20, move in order to detect STA, AP 12 collects the long-term sample (step 320) of the distance value of STA 16, collects the short-term sample-size distance value (step 322) of STA 16 subsequently continuously.The standard error in the difference between long-term distance and the short term distance value and mobile threshold value and these two range measurements and compare so that eliminate the mobile detection of falseness.(more information is referring to the 6th chapters and sections).When short term distance surpasses long-term distance and adds two error sums in the measurement greater than mobile threshold value, think that the station moves.Following false code is described this comparison.
IF((AssocaitedSTAs[n].short_term_distance-AssocaitedSTAs[n].distance＞
(movingThreshold+longTermStdError+shortTermStdError)) (step 324)
THEN
Moving=TRUE (step 326)
ELSE moving=FALSE; (step 328)
If AP 12 detects STA 16 and moves, AP 12 its TP compensation are set to 0 so, so that it is with maximum power transmission data (step 328).AP 12 maintains maximum power, till it detects that STA 16 no longer moves or be static.If STA 16 lose with the linking of its AP before, AP 12 determines that it is no longer mobile, AP 12 recovers the normal process of received signal intensity so, so that determine new appropriate TP offset (step 334) as previously mentioned.
In case AP 12 detects STA 16 and moves, it just brings into use another to test to detect STA and when stopped moving.Stopped moving in order to detect STA 16, AP 12 utilize relatively that long-term sample-size (Long Term Sample Size) obtains to the distance of STA 16 and the distance that obtains from up-to-date short-term sample-size (Short Term Sample Size).When AP 12 checks this difference just less than the standard error in these two measurements, to determine that STA 16 has stopped moving.Followingly carry out described test (step 330):
IF ((relevant STAs[n] the relevant STAs[myAP of .short_term_distance-] .distance)
＜(longTermStdError+shortTermStdError))THEN
Moving=FALSE; (step 332)
2.b AP auction
The purpose of auction is to optimize the mode of performance for wireless communications, to realize the distribution that STA 16 crosses over AP 12.Purpose is that STA 16 and their nearest AP 12 are linked, and takes into account loading (summation of the independent load of the STA 16 that links with AP 12) simultaneously.This allows the RF area of coverage of AP 12 and STA16 to reduce to minimum, guarantees not have AP 12 overloads simultaneously.
Especially, referring to Figure 21, AP collects the Bid (step 340,342) of any reception in the auction time interval.If receive Bid (step 344) from the STA 16 that receives Bid, so new solicited message replaces previous solicited message (step 346).Otherwise, for this STA 16 creates new clauses and subclauses (step 348).In either case, the age of request clauses and subclauses is reset (step 350).
When the auction time interval finishes (step 352), AP 12 handles the solicited message (in 802.11 environment of example, the auction time interval may be about for example 7.5 seconds) that receives.The age of all request clauses and subclauses is added 1 (step 354), and its age is greater than any request clauses and subclauses deleted (step 356) at largest request age subsequently.Subsequently according to the biased_distance_delta value to this list category (step 358).
Except receiving DRCP Bid, whenever, when STA 16 linked with AP 12, AP12 also received an indication.Referring to Figure 22, when receiving described indication (step 366), AP checks whether it has solicited message (step 368) from the up-to-date STA that links 16.Any solicited message deleted (step 370) that finds for the up-to-date STA that links 16.AP 12 also checks STA 16 whether in unsettled acceptance tabulation (step 372), if STA 16 in unsettled acceptance tabulation, these clauses and subclauses deleted (step 374) so, numAcceptsOut counts by successively decrease (step 376).When the auction time interval finishes, be considered to overtime from any unsettled acceptance in previous auction cycle, thereby unsettled acceptance tabulation be cleared, numAcceptsOut is reset.Have only AP 12 effective on allocated channel, just continue these processes.
3.STA initialization
The purpose of STA initial phase is to search suitable AP 12, and links with it, thereby provides access to WLAN to STA 16, and the operation of preparing DRCP agreement and algorithm.
Referring to Figure 23, when starting, STA 16 produces the tabulation (step 380) of the channel of STA 16 supports.In multi-PHY-variant STA (for example, supporting the STA of a plurality of frequency bands such as 802.11a/b/g), channel list will comprise crosses over all channels that each supports that frequency band is supported.
At first, STA 16 crosses over the frequency band of all supports, in scanning for beacon on all channels (for example, support STA of a plurality of frequency bands such as 802.11a/b/g will scan all channels in each a, b and the g frequency band) (step 382).Be chosen in the AP 12 (step 384) that receives under the maximum signal.
Best, under the situation of supporting a plurality of frequency bands, the selection of AP 12 considers also that to the wide band preferential selection of higher band that consequently for example realizes is such in 802.11 environment, preferentially be chosen in the AP 12 on 802.11a or the 802.11g, rather than the AP 12 that on the 802.11b channel, works.
In case selected a certain AP 12, STA 16 just verifies this AP and link with it (step 386).Carry out any security strategy that control links this moment.
During initialization, STA 16 also enables the DRCP agreement, so that STA 16 will receive DRCP Announce message (step 388).STA 16 enters STA optimizing phase (step 390) subsequently.
4.STA optimize
Initially link and inserted WLAN in case finished it, STA just carries out following function continuously to optimize its configuration:
Detailed survey.STA regularly adjusts its radio listening to other channel, keeps on its working channel simultaneously and the linking of its AP.Carry out this detailed survey of other channel, so that allow STA to receive DRCP Announce message from the AP that works at other channel.
Request.On STA one of any in the channel of its support, receive and handle the DRCP Announcements of all AP of work in comfortable its scope.It assesses out received power and from the load information of Announce message, if its find to compare with its current AP, the AP that it can link with it best, STA asks so, so that move to this AP.
Wireless power is regulated.STA adopts the TP offset that transmits in the Announce message from its AP, follow the tracks of this value when described value changes.
Move and detect.STA checks continuously whether it is leaving the AP that it links with it at present.If it detects itself and moves, it stops to participate in the DRCP request process so, and adopts when degenerating with linking of its AP next AP selection course of calling.
These functions are described in more detail below:
4.a STA detailed survey
Illustrate in greater detail other channel of STA 16 detailed surveies now, so that determine whether to send the process of DRCPBid message.In order to monitor DRCP Announce message, STA 16 regularly adjusts to its radio on other channel the channel that links except that it is present.But STA 16 must keep the AP 12 current with it to link, so that it can lost data packet.Thereby, STA 16 carrying out detailed survey during, grouping must be buffered.Various wireless communication systems structures can be provided for the means of different of grouping cache.
In general, referring to Figure 24, in the time interval (step 400), STA16 makes the predetermined grouping (step 402) to this STA 16 of its current AP that links 12 temporary cache in periodic scan.Can start grouping cache according to variety of way.For example, STA 16 can send the DRCP message to AP 12, cause described buffer memory, and perhaps AP 12 can regularly start buffer memory, and notice STA 16 it started buffer memory.When the grouping of STA 16 just had been buffered, STA 16 adjusted to another channel to its radio, and listened to beacon and DRCP Announce message (step 404) on this channel.This information is used to determine whether to ask another AP by AP 12.When trace interval finished, grouping cache was closed, and STA 16 receives the grouping (step 406) of its buffer memory from AP 12.
Figure 25 has stated for the STA detailed survey mechanism of using in 802.11 wireless networked environment.802.11 architecture provides energy saver mode expediently, according to principle of the present invention, energy saver mode can be used to this purposes.
Use for STA 16 802.11 energy saver mode is predetermined, so that they can close their radio so that energy-conservation in each time cycle.STA 16 can indicate AP, and they are just entering this energy saver mode.In response, the grouping of AP 12 buffer memory STA, STA 16 is in " sleep " simultaneously.AP 12 regularly sends special beacon message to STA 16.These beacon messages comprise about the information of any data that has been STA 16 buffer memorys whether.If the data that have been STA 16 buffer memorys, STA 16 " is waken up ".
The STA 16 that works in 802.11 environment according to a preferred embodiment of the invention uses 802.11 energy saver modes to leave channel and is other channel of DRCP Announce message detailed survey.After the channel detailed survey finished, STA 16 was returned to normal energy saver mode.The station that is not set to energy saver mode by management is facilitated as them by STA 16 and has been set to energy saver mode as yet.The STA 16 that is set to energy saver mode by management will have the more time detailed survey.
Especially, with reference to Figure 25, when trace interval begins (step 410), the current state of STA 16 its energy saver modes of inquiry.Remembered (step 412) by the energy saver mode (effectively, energy-conservation) that management is set.Energy saver mode is set to energy-conservation, and listens attentively to the time (time that STA 16 keeps sleep), if any, is increased a time cycle (step 414) that is called sweep time here.When the energy-conservation cycle began, STA 16 is in fact temporary transient to keep clear-headed, rather than dozes off as it tells AP that it wants to do.Be exactly beacon and the DRCP Announce message (step 416) in this other channel of time durations detailed survey.After carrying out detailed survey, STA 16 continues its energy-conservation cycle (step 418).This process repeats at each trace interval.Whenever STA16 not during detailed survey, the management configuration energy saver mode that its reduction is remembered.This trace interval for example can be, the twice in each beacon time interval.
The station that is not set to energy saver mode by management is facilitated just as they have been set to energy saver mode by STA 16 as yet, listens attentively to the time interval to be set to minimum value (that is each beacon).The STA 16 that is set to energy saver mode by management will have the plenty of time detailed survey.
During the detailed survey time interval, STA 16 is with its radio tuning to one different channels, so that listen attentively to beacon and DRCP Announce message passively.Which channel STA 16 keeps following the tracks of by detailed survey, all channels of detailed survey length by length, up to detailed survey all channels that are supported.STA 16 keeps following the tracks of all DRCP Announce message and the received power level of these message.
4.a.1 STA KnownAPs table
·AP-ID
Age
Channel id
Load factor
The TP compensation
Maximum power
Distance_samples (distance sample)
Distance
My_load_factor (my load factor)
Biased_distance (offset distance)
Set up STA KnownAPs table 430 as shown in Figure 27.For each beacon received or Announce message (step 432,434), STA 16 checks whether it has clauses and subclauses to be used for the AP-ID (step 436) of this message in STA KnownAPs table 430.If finding has, then STA upgrades this clauses and subclauses (step 438), otherwise it creates new clauses and subclauses (step 340), until be called the maximum (step 442) of the previous setting of Max Aps clauses and subclauses here.
·AP-ID
Channel id
Maximum power
·AP-ID
Channel id
The power that receives
Load factor
The TP compensation
Received power and TP compensation clauses and subclauses are tabulations, and wherein each clauses and subclauses in each tabulation are corresponding to being beacon or the Announce message that corresponding AP-ID receives.The received power level value changes in the RF channel easily with the distance that with Banzais is unit accordingly.STA 16 is that each clauses and subclauses in the knownAPs table preserve a plurality of these range measurements, makes that it can use to ask on average to compensate this variation, will further specify this below.For its oneself AP (that is, the current AP that links of STA), STA 16 averages on a large amount of relatively distance values, is called " long-term sample size " distance value here.For every other clauses and subclauses, STA uses less " request sample size " distance value.
In addition, STA keeps an age to each clauses and subclauses.Whenever receive an Announce message from AP, just will be reset to zero " 0 " age corresponding to these clauses and subclauses.To describe the part that request is handled as STA below, clauses and subclauses are by aging.
4.b STA power adjustments
With reference to Figure 28, all Announce message that STA 16 that link and chartered receives from the AP 12 that it linked.After receiving Announce message (step 556), STA record TP offset and adopts this value to compensate (step 558) as oneself the IP of STA in Announce message.
4.c STA request
Whenever STA detailed survey function has been finished the detailed survey of all channels, whether the information that STA 16 analyzes in the STAknownAPs table has potential " better " AP 12 to link with it to check.The notion what constitutes a better AP consider with AP be the distance of unit with Banzais, available data rate, and the loading on the AP (number of the STA that links) are if know.
With reference to Figure 29, general following work is handled in the STA request.When finishing detailed survey and on each channel, collect the sample of sufficient amount (step 450), STA knownAPs table 330 clauses and subclauses carry out other handle before by aging (step 452).The age of each clauses and subclauses increases progressively, and deletes any clauses and subclauses (step 454) of its age above the Max AP clauses and subclauses age.Because remove age field when receiving Announce message or beacon, this burin-in process will be removed those AP, that is, what is not all heard from these AP in " Max AP clauses and subclauses age " RQ cycle.
As mentioned above, STA 16 utilizes the variation that on average compensates in its range measurement.Before it finished further processing to this table, it need be corresponding to the long-term sample size distance value (step 456) of the STA knownAPs clauses and subclauses of its AP.In case STA 16 has the long-term sample size distance value of its oneself AP, so its waits for that up to begin to seek a better AP at it before, it all has request sample size distance value (step 458) for all clauses and subclauses in the knownAPs tabulation.This is to make the decision that moves to a new AP before the full information that has at it about other AP in the network.Yet for fear of ad infinitum waiting for possibly, any one the new AP for adding after it has long-term sample size distance value to its own AP can not postpone to handle knownAPs and tabulate.
By there being the clauses and subclauses of enough range measurement samples, STA 16 seeks a potential better AP.In a word, calculate offset distance for each clauses and subclauses.This considers the load (step 460) on available data rate and the AP.(that is, in 802.11 environment, 802.11 operator schemes (a, b, g)) are inferred data transfer rate according to received signal intensity and the technology used.After having calculated offset distance for all clauses and subclauses in the STA knownAP table, think that the AP with smallest offset distance is the optimal candidate object, if it seems to be better than its current AP (step 462), then send a Bid (request) (step 464).
Specifically, with reference to Figure 30, for each clauses and subclauses " n " in the STA knownAPs table (be called knownAPs[n]) at clauses and subclauses knownAPs[n] on carry out following processing.Index " myAP " is corresponding to the clauses and subclauses of the current AP that links of STA, i.e. knownAPs[myAP] be the clauses and subclauses of the current AP of STA 16.
As previously mentioned, in STA knownAPs table 430 apart from field, i.e. the knownAPs[n of each clauses and subclauses] .distance measures the distance (is unit with Banzais) to the AP of correspondence that averages on the sample at a plurality of (request sample size).As noted, this value is subjected to the influence of the variation in the RF channel.The request selection course should be preferably only when this new AP improves more best performance for STA really, rather than because this new AP of this variation when only seeming better, generation is to the selection of " better " AP.Variation in the range measurement of this new AP is by " request sample standard error " value representation relevant with this request sample size, and the variation in the range measurement of current AP by with big or small relevant " long-run standards error " value representation of long-term distance sample.Compare the current AP of STA, make the error minimize in the range measurement more favourable for given clauses and subclauses n.If these clauses and subclauses drop in the standard error sum of these two range measurements, then the corrected range of distance that is set to the current AP of STA by utilization is carried out.Corrected range " corrected_distance " is determined by following:
IF(ABS[knownAPs[n].distance-knownAPs[myAP].distance≤
(Bid Sample Std Error+Long Term Std Error)) (step 470) THEN
Corrected_distance=knownAPs[myAP] .distance (step 472)
ELSE corrected_distance=knownAPs[n] .distance (step 474)
4.c.1 distance to the load factor conversion
In STA knownAPs tabulation, write down the corrected range of each AP 12.This distance is used together in conjunction with the data that relate to specific wireless environment then, and in this specific wireless environment, AP12 is working to derive the estimation about the anticipated load factor of STA.For example, in 802.11 environment, this distance and 502.11 patterns (a, b g) are used to retrieve the anticipatory data rate of STA 16 from distance_to_rate table:
knownAPs[n].Data_rate＝distance_to_rate[knownAPs[n].mode]
[knownAPs[n].corrected_distance]；
(step 476)
The Table II of Figure 31 shows the example for the distance-rate calculations of 802.11 patterns.
Then, from rate_to_load table, retrieve anticipated load for this data transfer rate:
knownAPs[n].my_load_factor＝rate_to_load[knownAPs[n].data_rate]；
(step 478)
Show a example in the Table III of Figure 32 for the rate_to_load table of 802.11 networks.It should be appreciated by those skilled in the art that and how from the standard of other wireless environment, to realize distance_to_rate and rate_to_load table.Determine corrected_distance and my_load_factor parameter for each the clauses and subclauses n in the STA knownAPs table 430 by this way.
Represent any clauses and subclauses in the knownAPs tabulation of non-DRCP AP all to need to provide default value, make them also can be considered be used to link by the station for their load factor.The load factor of these acquiescences is to derive from the STA of the default amount of each AP value and the acquiescence of every kind of technology " average data rate ", and this AP value should be consistent in whole network.That is:
if(knownAPs[n].DRCP_Enabled＝＝FALSE)then
knownAPs[n].load_factor＝STAs_per_AP
*
rate_to_load[default_rate[knownAPs[n].mode]]；
When the load of the current AP (myAP) that determines STA 16, when myAP right and wrong DRCPAP, the load factor value of its acquiescence load that preferably increases the STA on this AP so.This helps to support in the front and back that STA and AP link the loading uniformity of this AP, promptly, because STA added its oneself load in the default load of this AP to before decision links with (non-DRCP) AP of its expection, so it must also add its load in the default load of this AP to after linking with this AP.
4.c.2 offset distance calculates
Utilize the my_load_factor of AP 12, the present load factor on the AP 12 (from the Announce message sink) and to the corrected range of AP 12, STA 16 calculates an offset distance value, when comparing, to take into account the loading on the AP 12 of expection, as shown in figure 29 with the loading on the current AP of STA 16.Calculate offset distance by following formula:
knownAPs[n].biased_distance＝
knownAPs[n].corrected_distance
*
(knownAPs[n].load_factor+knownAPs[n].my_load_factor)/
KnownAPs[myAP] .load_factor) (step 490)
Next the offset distance of current AP 12 that calculates STA 16 is to take into account with respect to the loading on current AP 12 in the loading on this expection AP.Followingly carry out this calculating:
knownAPs[n].my_ap_rel_biased_distance＝
knownAPs[myAP].distance
*
knownAPs[myAP].load_factor/
(knownAPs[n].load_factor+knownAPs[n].my_load_factor)
(step 492)
At last, following offset distance that is determined to expection AP and poor to the relativity shift distance of the current AP of STA 16:
knownAPs[n].biased_distance_delta＝
knownAPs[n].my_ap_rel_biased_distance-knownAPs[n].biased_distance
(step 494)
After having calculated offset distance (biased_distance) and offset distance δ value (biased_distance_deltas) for all AP in the knownAPs tabulation, whether STA 16 checks has any one offset distance δ value to be just (step 496).If no, then the current AP of STA 16 remains best AP, so still current with it AP of STA 16 link (step 498).For any positive offset distance δ value, best AP is exactly that AP (step 500) with the highest positive offset distance δ value.If best AP does not have DRCP ability (step 502), then STA 16 and this AP link (step 504).If best AP is DRCP AP (step 502), then send a request (step 506), and STA 16 continues normal runnings, up to it or receive DRCP Accept, perhaps finished the detailed survey sample size pass (pass) of all channels.If there is more than one AP to have identical the highest offset distance δ value (step 508), then STA 16 check in them any one whether be last AP (step 510) of its request, if it selects this AP (step 512) once more.
If utilize the AP-ID of the selected Aps AP-ID of coupling to receive DRCP Accept (step 514), then its TP offset of STA is set to 0 (step 516), and with the AP that receives this Accept from it link (step 518).STA 16 sends a DRCPRegistration Request (registration requires) (step 520) to AP now, and starts a timer (step 522) to interrupt each registration interval opening time.When timer expires (step 524), STA16 sends another DRCP Registration Request and the timer that resets.After receiving DRCPRegistration Acknowledge (step 256), timer invalid (step 528).
If after certain time cycle (step 530), do not receive DRCP Accept (step 414) in response to the request message of STA, STA keeps AP current with it to link.
After STA 16 linked with a new AP, STA 16 waited for before it continues as the processing of asking assessment knownAPs table, until it has collected range measurements that a large amount of (long-term sample size) arrives its new AP.
4.d STA moves detection
When STA 16 and AP 12 linked, STA 16 received DRCP Announce message from all AP 12 in its a-n radio range a-n.With reference to Figure 34, in case STA 16 collects a long-term sample size range measurements (step 540) from the Announce message that its AP 12 is received, it just can begin to move to detect handles.
IF ((knownAPs[myAP] .short_term_distance-knownAPs[myAP] .distance)＞(movingThreadhold+longTermStdError+shortTermStdError)) (step 544) THEN
Moving=TRUE (step 546)
ELSE moving=FALSE (step 547)
In case STA 16 detects it and moving (step 446), and as long as STA 16 does not detect it and stopped moving, STA 16 prevents and participates in request process (step 548), only just seeks a new AP when worsening its current linking of assurance.If STA 16 determine STA 16 lose with its AP link before no longer mobile, then STA 16 continues normal runnings, comprises the participation request process.
In moving detection, stopped moving in order to detect STA 16, the distance to its AP 12 that STA 16 relatively utilizes long-term sample size to derive out is with the distance of deriving out from a nearest short-term sample size sample.STA 16 checks whether this difference has just stopped moving with definite STA 16 less than the standard error in these two measurement results, and following false code has been described this test.
IF ((knownAPs[myAP] .short_term_distance-knownAPs[myAP] .distance)＜(longTermStdError+shortTermStdError)) (step 550) THENmoving=FALSE (step 552)
If STA 16 determines that it has stopped moving, and then restarts request process (step 554).
5. software architecture
According to this preferred embodiment, realize above-mentioned functions with the software among AP 12 and the STA 16 respectively.With reference to Figure 35, realize software according to a kind of layered architecture, make it comprise a kind of platform correlation module, carry out reciprocation with a kind of platform independence module.The advantage of this architecture is can transplant function of the present invention between different wireless architecture platforms.As shown in the figure, each AP12 comprises a platform independence module 560, and it is by AP API 562 and AP platform correlation module 564 reciprocations.Equally, each STA 16 (not shown) comprises a STA platform independence module 566, and it is by STA API 568 and STA platform correlation module 570 reciprocations.By in cable network 14 environment connected to one another, DRCP message can directly be transmitted between AP 12 by cable network 14 at AP 12.At AP only in the environment by wireless network 15 interconnection, AP 12 by DRCP message is delivered to separately the platform relevant layers each other and with STA 16 reciprocations.This makes wireless platform certain protocol message can transmit between AP 12 and STA 16 to realize the DRCP agreement.
With reference to Figure 36, Figure 36 shows AP architecture among Figure 35 and is applied to performance in 802.11 networked environment.Ap radio administration agent (ARMA) the 580th, the platform independence layer of software.Ap radio manager (ARM) the 582nd, the platform relevant layers of software.ARM software is actually to be realized within the specific element of the 802.11 several different platforms of AP.In 802.11 standards of institute's combination, can find more information about these elements.
With reference to Figure 37, website radio manager (SRM) the 584th, the platform dependent portion of STA software.As shown in the figure, SRM communicates by letter with 802.11 different platform element-specific.Website radio control agency (SRMA) the 586th, the platform independence part of STA software.Equally, the ap radio manager is the platform dependent portion of AP software, communicates by letter with 802.11 platform element-specific.SRMA communicates by letter with ARMA by using foregoing DRCP information.
These DRCP message are described now in further detail.In general, DRCP message can be encoded as the LLC Frame of standard, and the present invention does not get rid of this realization.But according to the preferred embodiment of realizing in 802.11 networked environment, the DRCP administrative messag is encoded as the newtype in the existing class frame.DRCP message is addressed to the group MAC Address, or independent MAC Address, and distinguishes by the existence of the DRCP protocol identifier in the agreement identification field of SNAP PDU.
Describe the DRCP message that works in APWLAN now in detail.Some DRCP message only send on WLAN as the IEEE802.11MAC management frames of subtype beacon, and other DRCP message then sends on the wire/radio network between WLAN or the AP as the SNAP PDU that is encoded to LLC1 and does not have numbering.
Figure 38 shows the coding of the DRCP message in the IEEE802.11 beacon frame.Da field is set to be suitable for the specific DRCP group MAC Address of this type of message, and BSS ID is the specific BSS-ID of DRCP.The standing part of beacon frame defines in 802.11 standards, and the variable part of this frame is used to carry the cell replacement of DRCP protocol message by establishment.According to a preferred embodiment, the AP that wishes to have the DRCP ability carries out automatic channel by DRCP Claim, Preclaim in the management frames of commutator type beacon and Announce message and selects and load balancing, avoids STA to attempt to link with AP simultaneously and receives in the message one with response.Therefore, except already mentioned DRCP agreement particular address field, also taked multiple measure.At first, " element ID " field comprises that specific to the OUI of DRCP agreement this prompting has the AP and the STA of DRCP ability, and this frame maintains a DRCP message.In addition, (non-DRCP) 802.11 beacons of standard comprise certain field in the main body of this frame field, as " supporting rate ", and " setting of FH parameter ", " setting of DS parameter ", " setting of CF parameter " or the like.(with reference to 802.11 normative documents of institute's combination to obtain more information.) coding 802.11 Claim, the management frames of the type beacon of Preclaim and Announce message or do not comprise these fields or these field values are set to 0.The non-DRCPSTA that may attempt in other cases to use DRCP beacon type frame to be used to link can't do like this, because they lack this information.
Figure 39 shows encoding D RCP message within the 802.11MAC of subtype number certificate Frame.DRCP message or be addressed to independent MAC Address perhaps is addressed to one of DRCP group MAC Address, and distinguishes by the existence of the DRCP protocol identifier in the agreement identification field of SNAP PDU.The DRCP message that sends on DS can format as shown in the figure, perhaps can similarly encode in another MAC Frame according to the DS medium.
According to this preferred embodiment, SRMA and ARMA and SRM and ARM reciprocation are to generate and/or to gather the information that need be used for producing or explaining the DRCP protocol message.Should point out that the DRCP agreement can realize and can not depart from the principle of the invention on non-802.11 primitive.Below be described in the primitive that uses in 802.11 environment.
5.a the enhancing of standard 802.11MAC business interface
ARMA and SRMA send and reception DRCP message by the 802MAC business interface of standard, have some enhancings.In STA and AP, all strengthened receiving interface and indicated the power that receives DRCP message to SRMA and ARMA respectively to allow SRM and ARM.Particularly, the semanteme of 802.11 MA-UNITDATA.indication service primitives is modified, shown in the text of using the underscore mark, to increase following received power parameter:
MA-UNITDATA.indication (
source address，
destination address，
routing information，
data，
reception status，
priorlty，
service class，
received power
)
The received power parameter has been specified the received signal strength signal intensity of MSDU (representing with DBM).The current level that received power value has indicated transmitting apparatus to hear, but the indication that does not provide transmitting apparatus whether just sending with full power.The potential power level that equipment can be heard can be determined when the transmitting power compensation (that is the radio amount of weakening (is unit with DB)) that this equipment uses is also known.
5.b the enhancing of standard 802.11 management interfaces
BSS Description
BSS Description parameter comprises the element list that BSS is described.In this tabulation, add an other element:
| Title | Type | Effective range | Explanation |
| Received power | Integer | -1 to-99 | Indication receives the power (dBm) of beacon from this BSS |
Send DRCP
Provide this mechanism to be sent in the DRCP message of encoding in 802.11 management frames of type beacon to allow ARMA.
MLME-SENDDRCP.request
This primitive is used for requiring to be sent on the ARM wireless medium DRCP message of encoding in 802.11 management frames of type beacon by ARMA.As shown in figure 34, this is a kind of beacon frame of specific type, and wherein the standing part of beacon frame defines in 802.11 standards, and the variable part of this frame is replaced by the single cell that carries DRCP message.
This primitive parameter is as follows:
MLME-SENDDRCP.request (
Destination Address
Message Length
DRCP Message
Quiet Channel
CTS Duration
)
| Title | Type | Effective range | Explanation | |
| Destination address | MAC Address | N/A | The specific DRCP group MAC Address that is suitable for this type of message | |
| Message- | Signless integer | 0..2312 | The eight bit word joint number of indication in the DRCP message field | |
| DRCP message | DRCP message | N/A | DRCP message | |
| Static channel | Boolean | FALSE (0) TRUE (1) | Sent clear to send (CTS) frame immediately before transmitting at beacon, indication is kept silent with the STA reply beacon transmission that AP links. | |
| The CTS | Signless integer | 16..255 second | Indication will be put into the value of the duration field of CTS frame.This value representative sends the required time (millisecond) of unsettled beacon frame, adds a short interframe space (SIFS) at interval.This parameter is that true time uses in the static channel parameter only. |
This primitive is generated by ARMA, to send on the wireless medium that requires DRCP message to encode in 802.11 management frames of type beacon.Send DRCP Claim and Hello message by this way.As previously mentioned, by at first sending before the CTS frame sends DRCP Hello message, ARMA can randomly make channel quiet.Particularly, if Quiet Channel parameter is true, then ARM sent a clear to send (CTS) frame immediately before beacon transmits.DRCP HelloCTS target MAC (Media Access Control) address is placed in the receiver address (RA) of CTS frame.The duration field of CTS is set to the value of CTS Duration parameter.
The standing part of beacon frame defines in 802.11 steps.DA is set to the DestintionAddress parameter value, and SA is the MAC Address of AP, and BSS ID is the BSS-ID of DRCP acquiescence.The variable part of this frame is substituted by the single cell of the element ID with DRCP agreement.Length field value and the information field that comprises DRCP message with this Message Length parameter.
MLME-SENDDRCP.confirm
This primitive is confirmed DRCP message is sent to ARMA.This primitive parameter is as follows:
MLME-SENDDRCP.confirm (
ResultCode
)
| Title | Type | Effective range | Explanation |
| ResultCode | Enumerate | SUCCESS, INVALID_PARAMETE RS, NOT_SUPPORTED | The result of indication MLME-SENDDRCP.request. |
This primitive is to be produced by MLME as the result of MLME-SENDDRCP.request, with the DRCP message of encoding in 802.11 management frames that are sent in the type beacon.The result that the notified thus transmission of ARMA DRCP requires.
Power Management Fib
As previously mentioned, STA can support a kind of mode of regular detailed survey be indication AP its be in energy saver mode, thereby impel AP buffer memory STA grouping in the STA detailed survey.This mechanism is supported STA indication AP, and it is in energy saver mode, and unactual enterprising ability of going into energy saver mode.
MLME-POWERMGTRIB.request
This primitive requires SME to use energy saver mode and AP reciprocation, so that the time of other channels of detailed survey to be provided.This primitive parameter is as follows:
MLME-POWERMGTRIB.request (
)
| Title | Type | Effective range | Explanation |
| Null | N/A | N/A | Printenv |
This primitive is produced by SRMA, uses sleepy time (if STA is in energy saver mode) of part or all sleepy time (if STA is in effective model) to impel MLME, so that other channels of detailed survey.
This requirement impels SRM:
1. preserve the setting of current power management mode
2. be provided with:
A. power management=Power_Save
b.WakeUp＝FALSE
c.ReceiveDTIMs＝FALSE
The notice AP its just using power managed modes.
This requires preparation SM:
1. when the energy-conservation cycle begins, by when keeping energising really, sending
MLME-PSSTART.indication notifies SRMA.
2. catch Any user or network management power mode bookkeeping, and impel them to use institute
The setting of preserving, rather than current effective setting.
MLME-POWERMGTFIB.confirm
The variation of power managed modes confirmed in this primitive to SRMA.This primitive parameter is as follows:
MLME-POWERMGTFIB.confirm (
ResultCode
)
| Title | Type | Effective range | Explanation |
| ResultCode | Enumerate | SUCCESS, INVALID_PARAMETE RS, NOT_SUPPORTED | The result of indication MMLME-POWERMGTFIB. request. |
This primitive is to be produced by MLME as the result of MLME-POWERMGTFIB.request, with the simulation energy saver mode.The variation of the notified thus indicated power mode of SRMA.
Power Save Start
It can begin detailed survey this mechanism notice SRMA.
MLME-PSSTART.indication
The beginning in this primitive indication energy-conservation cycle of SRMA.In fact STA does not close its radio, but enters sleep state at the moment, but preferably, it does not send output frame after sending this indication, receive MLME-PWRMGMTFIBCONTINUE.request up to it.This primitive parameter is as follows:
MLME-PSSTART.indication (
)
| Title | Type | Effective range | Explanation |
| Null | N/A | N/A | Printenv |
This primitive be by SME indicate the energy-conservation cycle begin produce.SRMA is the beginning in notified energy-conservation cycle thus.
Power Management Restore
This mechanism further supports STA to indicate it to be in energy saver mode to AP, and does not in fact enter the ability of energy saver mode.
MLME-PWRMGMTRESTORE.request
This primitive tells MLME that it will recover user configured energy saver mode.This primitive allows SRMA to tell MLME, and it no longer needs to pretend to claim energy-conservation (MLME is transmitted back in the control on energy-conservation) to AP.This primitive parameter is as follows:
MLME-PWRMGMTRESTORE.request(
)
| Title | Type | Effective range | Explanation |
| Null | N/A | N/A | Printenv |
When not working, detailed survey mechanism produces this primitive.Receive this primitive and make SRM recover the power managed modes setting of being preserved, and:
1., then force waking state immediately if the energy saver mode of Bao Cuning is ACTIVE;
2., then continue normal energy saver mode operation if the energy saver mode of Bao Cuning is POWER_SAVE.
MLME-PWRMGMTRESORE.confirm
This primitive is to the variation of SRMA affirmation power managed modes, and this primitive parameter is as follows:
MLME-PWRMGMTRESORE.confirm(
ResultCode
)
| Title | Type | Effective range | Explanation |
| ResultCode | Enumerate | SUCCESS. INVALID_PARAMETE RS, NOT_SUPPORTED | The result of indication MLME-PWRMGMTRESO RE.request. |
This primitive confirms that by MLME SME has carried out MLME-PWRMGMTRESORE.request and produced, and does not produce this primitive before this variation of indication.When receiving this primitive, the variation of the notified indicated power mode of SRMA.
Power Management Fib Continue
In case finished detailed survey, this mechanism just notify SRMA its " controlled " radio and passed on power save mode (clear-headed or sleepy).
MLEM-PWRMGMTFIBCONTINUE.request
It is very safe that this primitive tells that MLME enters waking state, and when wishing transmit frame.This primitive parameter is as follows:
MLEM-PWRMGMTFIBCONTINUE.request (
)
| Title | Type | Effective range | Explanation |
| Null | N/A | N/A | Printenv |
When having finished detailed survey, SRMA produces this primitive.When receiving this primitive, if necessary, MLME can transmit user data frame.
MLEM-PWRMGMTFIBCONTINUE.confirm
The variation of the power management state of permission confirmed in this primitive.This primitive parameter is as follows:
MLEM-PWRMGMTFIBCONTINUE.confirm (
ResultCode
)
| Title | Type | Effective range | Explanation |
| ResultCode | Enumerate | SUCCESS, INVALID_PARAMET ERS, NOT_SUPPORTED | The result of indication MLEM.PWRMGMTFIBCON TINUE.request. |
This primitive confirms that by MLME SME has carried out MLME-PWRMGMTFIBCONTINUE.request and produced.Before this variation of indication, do not produce this primitive.SRMA receives this primitive and is used to notify the energy saver mode that is allowed to change.
Channel Out
This mechanism is supported to the idle ability of ARMA indicating channel.
MLME-CHANNELOUT.indication
This primitive has become unavailable to the previous available channel of ARMA report.This primitive parameter is as follows:
MLME-CHANNELOUT.indication (
Channel
)
| Title | Type | Effective range | Explanation |
| Channel | Integer | 0-255 | Channel Identifier |
This primitive is produced by MLME when channel becomes unavailable.Receiving primitive makes ARMA can delete this channel from its channel Mapping.
Channel In
This mechanism provides the ability that enters work work to channel of ARMA indication.
MLME-CHANNELIN.indication
This primitive reports that to ARMA previous disabled channel has become available.This primitive parameter is as follows:
MLME-CHANNELIN.indication(
Channel
)
| Title | Type | Effective range | Explanation |
| Channel | Integer | 0-255 | Channel Identifier |
But this primitive was produced by MLME in channel time spent that becomes.Receiving primitive makes ARMA this channel can be added in its channel Mapping.
Beacon Notify
This mechanism support utilizes the ability of same any other AP of Channel Detection.
MLME-BEACONNOTIFY.request
When receiving a beacon, this primitive requires MLME notice ARMA.Beacon for each reception all has an indication, all produces an indication when receiving a beacon on current channel.This primitive parameter is as follows:
MLME-BEACONNOTIFY.request (
Notify Enable
)
| Title | Type | Effective range | Explanation |
| Notify Enable | Boolean type | True or False | If True, any beacon that expression will notify PIOTE to receive; If False then forbids this mechanism. |
This primitive is to be produced by ARMA when ARMA expects the notice of received any beacon on its oneself channel.MLME receives this primitive makes MLME can start a pattern, if receive any beacon whereby, ARMA will obtain notice.
MLME-BEACONNOTIFY.confirm
The variation of beacon informing mechanism confirmed in this primitive.This primitive parameter is as follows:
MLME-BEACONNOTIFY.confirm (
Resultcode
)
| Title | Type | Effective range | Explanation |
| ResultCode | Enumerate | SUCCESS, INVALID_PARAMETE RS, NOT_SUPPORTED | The result of indication MLME-BEACONNOTIFY. request. |
This primitive is to be produced by MLME as the result of MLME-BEACONNOTIFY.request.ARMA receives the variation that this primitive is used to notify indicated Beacon Notify.
MLME-BEACONNOTIFY.indication
This primitive is reported in data channel to ARMA and receives a beacon.This primitive parameter is as follows:
MLME-BEACONNOTIFY.indication (
BSSDescription
)
| Title | Type | Effective range | Explanation |
| BSSDescr iption | BSSDescrip tion | N/A | BSS Description (being included in any additional Description Element of definition in 0) about each beacon of receiving. |
If on data channel, receive a beacon, then produce this primitive by MLME.Notice that produce an independently MLME-BEACONNOTIFY.indication for the beacon of each reception, therefore, this primitive parameter only comprises a BSSDescription.When receiving this primitive, the signal strength signal intensity of notified this beacon of ARMA and this beacon of reception.
5.c DRCP message preferred implementation
The mode that above-mentioned primitive is used for realizing the DRCP message of 802.11 environment is below described.Figure 40 shows the conclusion of the DRCP message that is used to realize aforementioned functional.Figure 41 shows employed Field Definition in the DRCP message, and is as follows:
DRCP Preclaim
Figure 42 shows the form of DRCP Preclaim message.DRCP Preclaim message is to encode in 802.11 management frames of type beacon.ARMA utilizes the MLME-SENDDRCP.request management primitive to send DRCPPreclaim message by following parameter:
Destination address-DRCP ALL ARMAs Group MAC Address
Message-length-12
DRCP message-Preclaim message
Static channel-FALSE (0)
CTS duration-0
DRCP Claim
Figure 43 shows the form of DRCP Claim message.DRCP Claim message is to encode in 802.11 management frames of type beacon.ARMA utilizes the MLME-SENDDRCP.request management primitive to send DRCP Claim message by following parameter:
Destination address-DRCP ALL ARMAs Group MAC Address
Message-length-16
DRCP message-Claim message
Static channel-FALSE (0)
CTS duration-0
DRCP Announce
Figure 44 shows the form of DRCP Announce message.DRCP Announce message is to encode in 802.11 management frames of type beacon.ARMA utilizes the MLME-SENDDRCP.request management primitive to send DRCPAnnounce message by following parameter:
Destination address-DRCP ALL Agents Group MAC Address
Message-length-16
DRCP message-Announce message
Static channel-FALSE (0)
CTS duration-0
DRCP Bid
Figure 45 shows the form of DRCP Bid.The LLC 1 that DRCP Bid message is encoded as in the Frame does not have numbering SNAP PDU.The peculiar MAC Address of AP of target ARMA that this message has been addressed to its illustrated.SRMA sends DRCP Bid message by the MAC business interface of standard.
DRCP Accept
Figure 46 shows the form of DRCP Accept.The LLC 1 that DRCP Accept message is encoded as in the Frame does not have numbering SNAP PDU.The peculiar MAC Address of STA of target SRMA that this message has been addressed to its illustrated.ARMA sends DRCP Accept message to be relayed to DS by the MAC business interface of standard.
DRCP Registration Request
Figure 47 shows the form of DRCP Registration Request message.The LLC 1 that DRCPRegistration Request message is encoded as in the Frame does not have numbering SNAPPDU.The peculiar MAC Address of AP of target ARMA that this message has been addressed to its illustrated.SRMA sends DRCP Registration Request message to be relayed to DS by the MAC business interface of standard.
DRCP Registration Acknowledge
Figure 48 shows the form of DRCP Registration Acknowledge message.The LLC 1 that DRCPRegistration Acknowledge message is encoded as in the Frame does not have numbering SNAP PDU.The peculiar MAC Address of AP of target SRMA that this message has been addressed to its illustrated.ARMA sends DRCP RegistrationAcknowledge message to be relayed to DS by the MAC business interface of standard.
6. move and detect
As previously mentioned, AP and STA determine to move together with the error measure of expection based on the short-term and the long-term average assessment of parameter.According to an aspect of the present invention, realize mobile the detection by using a kind of wide in range inventive concept, this inventive concept provides a kind of mode to come based on the short-term of discrete DATA REASONING and the average for a long time dynamic attribute of determining system.Principle of the present invention is applicable to any system that wherein can change discrete measurand widely.Yet for clarity sake, now the present invention is described according to the application-specific of wireless network.
In wireless network shown in Figure 1, Wireless Networking user (before also being referred to as " STA ") links with an access point (AP).AP provides by radio frequency (RF) signal and is connected the user who links with network.The RF that various AP are used to provide seamless covers, make when the user from an AP when another AP moves, the user will link with nearer AP (or the lighter AP of load), thereby keeps seamless network function.Therefore can determine the user with respect to the position of AP in case can determine the user current whether move extremely important.This system that makes can guarantee that the user becomes fast and nearest AP links, thereby makes overall system performance the best.When the user moves or during away from AP to AP, received power level (that is the power of the RF signal that receives from AP of user) increases respectively or reduces.Therefore, determine that a kind of mode that the user moves is by the monitoring received power level.
Yet as if even when the user is not mobile, received power level also changes very big.For example, Men switch may cause the increase or the decay of user's received power level.Near the people who user's antenna, waves even will cause the increase or the decay of received power level.Environmental interference also may cause the variation of received power level.It is mobile that the different variations of these of power level may cause that the user appears in, and in fact it does not move.This may cause user's unnecessary roaming between AP, especially a plurality of AP very near and also their transmitted power level be lower than in the environment of maximum power.As selection, because the variation of the signal power that these influences cause may be covered the fact that the user is really moving.In the case, system possibly can't detect this moves, and this user and suitable AP are linked.Figure 49 shows the user who moves for not, the discrete measurement of received power and time relation curve example.As can be seen, the inaccurate of data sampling hindered for any hypothesis that moves in a direction or other directions.
As a more special example, consider 802.11 wireless networks.AP in this network provides the maximum bandwidth of 54Mbps.Along with the distance with AP increases, bandwidth reduces.Suppose that adjacent AP has adjusted their transmitting power, make each AP provide diameter to be approximately the sub-district of 10 feet 54Mbps.The user who is walking about may pass this sub-district in 2 seconds.On the other hand, be sitting in user on the stool (near the center of sub-district, just adjoin AP) stand up and the edge that escape to the sub-district has only been walked 5 feet, it or not 10 feet, therefore the time of user's only use more than 1 second just arrives in the sub-district or leaves the sub-district, and why these examples must carry out the enlightenment that fast power is estimated based on discrete the measurement if providing.Increase sampling rate and improved precision, but this may cause that also the expenses such as processing expenditure on wireless signal-path band width, interrupt activity and the subscriber equipment increase.Some subscriber equipmenies may be simple utensils, as phone, digital assistants or the like, and have only very limited disposal ability.Therefore, between sample rate and expense, compromise must be arranged.
According to a possible execution mode, on time window with the time interval measurement power level and make roaming decision.In the 802.11a network, as user during from about 1 foot of the distance of AP, the power of this AP is set to make its sub-district with 54Mbps, and the diameter of this sub-district is approximately 10 feet, and user's true mean power level should be approximately-38dbm.Suppose to wish near this true mean (that is the power level that estimate), 99% confidential interval is arranged.Yet because the intrinsic inaccurate reason of environmental impact (waving or the like) and this enforcement measurement itself, measurement result is variable.Inaccurate and the statistics variations of among the tentation data result these has the standard deviation of σ=15dbm on data distribute.With reference to Figure 50, if in this Distribution Statistics, only get 8 samples, so near 99% confidential interval this (truly) average be-23.4dbm～-52.6dbm.
99% confidential interval has | 52.4-23.4|=29.2dbm, or the scope of about 30dbm.This be approximately+_ 15dbm.Therefore, because the variation in the signal, if only get 8 samples, just " real power " existence-23.4dbm known to then～-somewhere between the 52.6dbm, and drawing of this conclusion has only 99% assurance.
If can stand lower precision, for example 95% or even 90% confidence level, then the scope that obtains of result will be narrower.But lower confidence interval has increased the possibility of " certainly false ".False occur in the user certainly and be determined and move but when in fact not moving, make the user unnecessarily roam into another AP.Wish to make the sure phenomenon of this vacation minimum, because they incite somebody to action the unnecessarily bandwidth of consume valuable.
When the distance of user and AP doubled, user's received power reduced 6db.Therefore when user (almost arriving the edge of sub-district) when moving to from 1 foot of AP from 2 to 4 feet of AP, then (truly) mean receiving power respectively from-38dbm be reduced to-44dbm is to-50dbm.But, can find out from Figure 51, when 8 samples attempting to utilize 99% confidential interval in the data to get are estimated mean receiving powers, can't determine that the user moves during this moves.This is real unknown because of true mean.Known to just he be in-23.4dbm～-somewhere between the 52.6dbm.Therefore, can't determine that when only getting this several sample the user moves away from AP, still not mobile near AP.
Certainly, increase the sample number of being got and to reduce error range.If get 20 power sample, so 99% confidential interval be-29.1dbm～-46.9dbm.But get a lot of samples and will spend the long time, unless channel overhead increases.
Consider that now getting n sample produces estimation, and then get second estimation of n sample generation.Relatively whether these two estimations can draw the conclusion whether user is moving then.If the confidential interval around each estimator is very big, for example 99%, there is result's spectrum so, but also is to determine that the user moves or away from AP or do not move at all towards AP.In Figure 51, just to move away from AP in order to inform the user with 99% assurance, the upper edge of right confidential interval must be positioned at the below, lower edge of left confidential interval.
Consider two kinds of basic schemes of relevant motion in wireless network:
1. the user stays in one rational period an of place and moves to a reposition then, and the user needs communication when mobile, but the user moves often and stops then, is staying for a while somewhere again.Perhaps similar, the user can move in a localized area very lentamente, moves to another zone then more quickly.
2. user's persistent movement.
In the example of first kind of scheme, the activity of thumping majority user in wireless network described, the precision that power is estimated can improve greatly.According to principle of the present invention, two of received signal intensity on average are maintained as mentioned above.But one is the nearest N that gets on sliding window
1Individual sample, and another is to use N
2Individual sample long-term average.Therefore, on average long-term and short-term averaging all is maintained.With reference to Figure 52, near the confidential interval long-term average is very little, and the error in this estimation is almost removed fully.Therefore, the potential uncertain result in this decision is minimized.
In Figure 53, when the user moves away from AP, the upper edge of right confidential interval will drop to and be lower than long-term average (it has the confidential interval of approaching basically ± 0db).
What for a given application, need to determine to get a sample (N
2), make long-term average estimation be essentially 0 error.And what sample (N hope need to determine in short-term averaging
1) making decision with 99% assurance.
Suppose that the user just has been initially located in the position of leaving 1 foot of AP, and move to the edge of 10 feet sub-districts.Purpose is to find to need what samples to determine that with 99% precision the user moves, so that produce the most healthy and the strongest execution mode from the overall performance perspective.If possible " ideally " measures power, whenever the user will observe when the distance of AP doubles-the reduction amount of 6db.With reference to Figure 54, if be-38dbm, then be-44dbm to be-50dbm that 4 feet places are almost at the edge of this sub-district at 4 feet places at 2 feet places when the user locates power level at 1 foot.As can be seen from the figure, when short-term averaging for the upper edge of-50dbm 99% confidential interval just be lower than-during 38dbm, the width of confidential interval is ± 12db so.In order to realize this confidential interval, the standard deviation of supposing the data of previous hypothesis is σ=15db, then needs 14 sample (N in short-term
1).Utilize this 14 samples, 99% confidential interval is-60.7dbm＜-50＜-39.2dbm.
In the example of this wireless network, supposed that the user can go to the edge of sub-district from the center of sub-district in 1.5 seconds, therefore every 100 milliseconds of needs samplings of 1.5 ÷, 14 ≈.As further improving, wish to use 16 samples to make and to do division through shift operation by processor.This has improved the computational efficiency on the subscriber set.This makes sample rate improve an inappreciable amount.
About long-term average, reasonably be the confidential interval of tolerance ± 1db long-term estimation near.This interval needs tight more, and then the user must stop longlyer near AP, perhaps will keep static relatively in certain zone, so that this convergence in mean.Wish to calculate the user and stay in the precision required shortest time of a place with 99% confidence level realization ± 1db.Reasonably suppose, based on the signal intensity samples of getting from the message of AP reception every 50 milliseconds.With reference to the form shown in Figure 54, if the user stayed near the AP (1 foot) about 1.5 minutes as can be seen, then per 50 milliseconds sample occurs, and the precision that power is estimated becomes less than+1db.
Therefore, the preferred implementation utilization of current wireless network example: (a) at N
1Short-term averaging on=16 samples, (b) long-term average on 2048 samples, and (c) get N so far
2Individual sample is long-term average to calculate.This process is as follows:
(1) calculates continuously for a long time on average.Before being taken to few 2000 samples, on average " do not stablize " for a long time.When wanting 50 milliseconds, each sample need spend 1.5 minutes.A kind of execution mode preferably accumulates 2048 samples so that this division is shift operation.
(2) utilize nearest N
1=16 sample calculation short-term averagings (use 16 rather than 14 makes division to realize by displacement).
(3) when the difference of long-term and short-term averaging during, then mobile with 99% precision known users greater than 12db.
(4) when the user roams into a new AP, the counter reset that is used to calculate long-term average sample is 0.Then for a long time on average once more for other 2048 sample instabilities.
Often rest in the environment that is shorter than 1 second in the sub-district the user, long-term estimation can be used based on less sample.Yet this will cause false sure risk to increase.Can consider that several possibilities reduce false sure appearance.
(1) if the user has just arrived a new sub-district (that is N,
2≤ 32), before roaming decision based on power, permission needs at least 32 samples so.This just introduces some hysteresis in system.Still will exist some certainly false.If the user roams into a new AP and returns old AP then, then may occur certainly false.This may require for example N
2≤ 64.This help confidential interval be-42.8dbm＜-38＜-33.1dbm.
(2) consider signaling rate.For example, producing a plurality of sample (N
2) time, on average accumulate for a long time.If but the user's data rate reduces, then the user has moved to the outside of the inner loop of 54Mbps by definition.Should start roaming in this point.
(3) in case the user moves to a new sub-district, the user will become " adhesion ", and attempt to rest on there up to the edge of user near the sub-district.Here require for example N
2〉=128, add and see that reducing data transfer rate comes in handy.
In general, (for example, " being the wireless network user that moves ") wants the short-term of computing system variable (for example signal strength signal intensity) and for a long time on average in needs are determined the system of specific dynamic attribute.Calculate acceptable short-term and long-term average between difference, this difference has been determined system performance (for example, the user moves) for certain.
With reference to Figure 55, as follows as these step 1:
1. define the system dynamics attribute (step 600) that to determine.For example, in wireless network example, the dynamic attribute that determine is whether the user moves.In the network use-case, whether the dynamic attribute that determine will increase user bandwidth.
2. the system variable that will monitor of definition is to determine dynamic attribute (step 602).For example, in wireless network example, this variable is a received signal intensity.In the network use-case, this variable can be that the user is injected into the packet count in the network.
3. determine the statistical property (step 604) that system variable is measured.This will comprise the standard of contributive each system of statistics variations of system variable and analysis and environmental factor.In wireless network example, the standard deviation of signal strength measurement is subjected to inaccuracy, spatial event and the mobile influence of ambient noise, enforcement.In the network use-case, standard deviation is subjected to the speed of burst degree, the subscriber computer of the traffic carrying capacity that the user produces, with the competition of other Networks with interweave and influence and the influence of higher layer network protocol parameter.
4. for indicating the system variable of having determined the dynamical system attribute to select the scope (step 606) of true mean.For example, in wireless network example, when the true mean of signal strength signal intensity had changed 12db, system property-user moved-by sure determining.In the network use-case, can determine whether the true mean that is injected into the packet count in the network by the user surpasses threshold value, and whether user's bandwidth should increase.
5. choose confidential interval (step 608) based on the precision of the decision that the dynamical system attribute has been done." certainly false " determines and the speed of " vacation is negated " decision is that the levels of precision of being estimated the dynamical system attribute is controlled.Calculate this attribute with higher confidential interval and improved this precision.In wireless network example, confidential interval is 99%.
6. calculate the sample size of the variable that must get, make that near the confidential interval the given tolerance (as average) causes a broadening, this broadening is minimised as scheduled volume (step 610) based on desired decision precision.In wireless network example, this scope is ± 1db.
7. the sample based on the above-mentioned at least quantity that obtains in step 6 is provided with long-term average (step 612).(should be average with respect to the moving window accumulation.)
8. give the scope of selecting in the step 4 that fixes on, the sample number of the variable that calculating must be got makes that near the confidential interval the given tolerance (as average) causes a broadening (step 613) less than this scope.This calculating depends on the standard deviation of known way.This calculating is referred to as " sample size estimation " in the statistics field.It is meaningful and represent whole all members on statistics to use the statistical research of all members' subclass (N) need be designed such that according to the inference of having done in the sample set.Particular technology or implicit hypothesis about the statistical property of the dynamical system variable that obtains in step 3 are used to calculate the sample set size.The more information of the known statistical method of calculating for sample size please refer to " Statistical Analysis ", Sam Kash Kachigan, Radius Press, NY1986 (ISBN:0-942154-99-1), particularly Section 8-11, pg157, " Parameter Estimation; Sample Size Selection for LimitingError ", and Section 9-10, pg 189 " Sample Size Selection froDesired Power ".
9. based on the sample size that obtains in step 8 short-term averaging moving window (step 614) is set.
10. calculate the absolute difference (step 516) between on average long-term and the short-term averaging.If this difference is greater than selected scope in the step 4, then the dynamical system attribute is determined (step 618) for certain.In this wireless network example, when difference surpasses this scope, then know that with 99% confidence level the user moves or moves.In the network use-case,, represent that then the user has been given higher bandwidth if the difference of short-term averaging classified counting and long-term average minute counting surpasses selected scope.If the difference of on average long-term and short-term averaging is greater than selected scope in the step 4, then the dynamical system attribute is determined (step 620) as yet for certain, and continues to gather N
1Individual moving window sample.
The block diagram of realizing Wireless Networking of the present invention system shown in Figure 56.User (STA 16) communicates by letter with AP 12 by wireless network.The user sends message to AP, the signal strength signal intensity that receives from AP that the indication user feels.These message are gathered (640) by AP.Processor 642 among the AP utilizes these message to calculate short-term and long-term average according to the described process of Figure 55.Indication 644 is set when definite user is mobile.
The block diagram of realizing a preferred embodiment of wireless networked systems of the present invention shown in Figure 57.Subscriber equipment (STA 16) is communicated by letter with AP by wireless network.User message collection mechanism 646 receives the received signal intensity of message and monitoring message from AP.Processor in the subscriber equipment or hardware state machine 648 utilize the signal strength signal intensity of message to calculate long-term and long-term average according to the described process of Figure 55.When subscriber equipment determines that when mobile, the user sends indication or message 650 to the AP that requires to roam.
Shown in Figure 58 can be used for keeping required short-term and long-term on average a kind of mechanism of process of carrying out Figure 55 by the processor in the execution mode among Figure 56 or Figure 57 to determine to move.Keep two circular buffers 652 and 654, one to be used for long-term average one and be used for short-term averaging.Use circular buffer to make and to realize that on the time sliding window power sample is average.In circular buffer,, remove the oldest sample when when buffer adds a new samples.In aforesaid wireless networking example, 16 samples that the storage of short-term averaging circular buffer is nearest, and long-term average circular buffer is stored about 1024 or 2048 samples.Certainly, these sample sizes will change with concrete application.Can reasonably use based on integrator on average be used for long-term average, but this scheme is overflowed by buffer possibly.
Calculate short-term averaging 656 and long-term average 658 based on the content in each circular buffer 652 and 654.The allowed band 662 that comparator 660 utilization is stored and long-term average 656 and short-term averaging 658 produce according to the process of Figure 55 and move indication 650.
A kind of required short-term and long-term on average optional mechanism of process of carrying out Figure 55 that can be used for by the processor among Figure 57 or Figure 56 keeping shown in Figure 59 to determine to move.According to this mechanism, circular buffer accumulates a small amount of sample, for example 16, is used to calculate short-term averaging.Preserve the result of calculation (656a-656n) of each short-term averaging.As calculated with the short-term averaging of having preserved certain quantity after, calculate long-term on average average as the short-term averaging of all accumulation.This scheme is called as " batch processing device ".This scheme is particularly useful for comprising the system of limited storage resources.
Though for example understood and be applicable to wireless network, the above-mentioned aspect of the present invention that is particularly useful for 802.11 networks, it will be apparent to those skilled in that the present invention can also be applicable to any wireless communications environment, comprise radio data network, wireless telephony network and wireless I/O channel.All aspects of the present invention can realize by hardware or software.Because software architecture is convenient to transplant in the various hardware platform time, so preferred embodiment has been described to software architecture.
Should be understood that each functional block of the flow chart of being illustrated and the combination of the functional block in the flow chart can realize by computer program of instructions.These computer program instructions can be installed on computers, in the device microprocessor that embeds (for example at AP or the microprocessor that in STA, finds), or other programmable data processing device to be to produce a kind of machine, the device of function that makes the instruction of carrying out to create to be used for one or more functional block appointments of being implemented in flow chart on computer or other programmable data processing device.These computer program instructions also can be stored in the computer-readable media, vectoring computer or other programmable data processing device are worked in a particular manner, make the instruction that is stored in the computer-readable memory can produce a kind of manufacturing commodity, it comprises the command device that is implemented in the function of appointment in one or more flow chart functional blocks.This computer program instructions can also be installed in computer or other programmable data processing device, make it possible on computer or other programmable devices, carry out a series of operating procedure, produce a computer implemented process, make the instruction of on computer or other programmable devices, carrying out to be provided for being implemented in the step of the function of appointment in one or more flow chart functional blocks.
Those skilled in the art will readily understand, define functional programs of the present invention and can send computer in a variety of forms to, these forms including, but not limited to: (a) at the information that can not write permanent storage on the medium (read-only memory device in the computer for example, as can by ROM or the CD-ROM dish that Computer I/O annex is read); (b) be stored in the information (for example floppy disk and hard disk drive) that to write on the medium changeably; Or (c) utilize baseband signaling or broadband signalling technology transfer to give the information of computer by for example communication medium, the broadband signalling technology comprises the carrier signalling technology, as by computer or through the telephone network of modulator-demodulator.
Though described the present invention by above-mentioned exemplary embodiment, it will be apparent to one skilled in the art that and on the basis of not departing from inventive concept disclosed herein, the embodiment that is illustrated to be made amendment and to change.In addition, though the program command structrual description of the various signals that linked these preferred embodiments, person of skill in the art will appreciate that this system can use various specific order structures.Therefore, except the spirit and scope of appended claims, the present invention will not be subjected to other restriction.
Claims (30)
1. equipment comprises:
Can select automatically one of a plurality of radio-frequency channels with other device communicating devices, wherein carry out the selection of radio-frequency channel so that be minimized, and send the selection of radio-frequency channel to other device by message with the radio frequency interference of other devices.
2. equipment comprises:
The logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for during described trace interval, receiving logic about the message of described a plurality of radio-frequency channels;
Be used to keep the logic of channel Mapping, described channel Mapping all has clauses and subclauses in described a plurality of radio-frequency channels each, if receive one or more message on channel, then Dui Ying clauses and subclauses further are included in the device ID that sends at least one device of message on the described channel;
Be used for from the logic of channel Mapping selective channel;
Be used for during requiring the time interval, sending logic about the message of selected channel;
Be used for during requiring the time interval, receiving logic about the message of selected channel; With
Be used for determining the logic whether described equipment will begin to communicate by letter with other devices on the described channel based on characteristic about the reception message of selected channel.
3. according to the equipment of claim 2, the wherein said logic that is used for keeping channel Mapping further is each device ID storage power level of each clauses and subclauses of described channel Mapping, and the described channel that is used for selecting not have from the logic of channel Mapping selective channel device ID perhaps selects to have the channel of device ID of the power level of minimum storage.
4. the employed method of device in the wireless communications environment, described method comprises step:
Automatically select one of a plurality of radio-frequency channels to communicate by letter, wherein carry out the selection of radio-frequency channel, so that be minimized with the radio frequency interference of other devices with other devices; With
Send the selection of radio-frequency channel to other device by sending message.
5. method comprises step:
The a plurality of radio-frequency channels of scanning during trace interval;
During described trace interval, receive message about described a plurality of radio-frequency channels;
Keep channel Mapping, wherein said channel Mapping all has clauses and subclauses in described a plurality of radio-frequency channels each, if receive one or more message on channel, then Dui Ying clauses and subclauses further are included in the device ID that sends at least one device of message on the described channel;
Selective channel from described channel Mapping;
During requiring the time interval, send message about selected channel;
During requiring the time interval, receive message about selected channel; With
Based on characteristic, determine whether described equipment will begin to communicate by letter with other devices on the described channel about the reception message of selected channel.
6. according to the method for claim 5, wherein be used for keeping the step of a channel Mapping further to be included as the step of each device ID storage power level of each clauses and subclauses of described channel Mapping, and wherein be used for selecting the step of a channel to select do not have device ID, or have the channel of the device ID of the power level that has minimum storage from channel Mapping.
7. program product, described program product comprises computer-readable medium, has embedded in the described computer-readable medium to be used to store data computing machine program, described computer program comprises:
Can select the logic of one of a plurality of radio-frequency channels automatically, wherein carry out the selection of radio-frequency channel,, wherein send the selection of radio-frequency channel to other device by message so that be minimized with the radio frequency interference of other devices to communicate by letter with other devices.
8. program product, described program product comprises computer-readable medium, has embedded in the described computer-readable medium to be used to store data computing machine program, described computer program comprises:
The logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for during described trace interval, receiving logic about the message of described a plurality of radio-frequency channels;
Be used to keep the logic of channel Mapping, described channel Mapping all has clauses and subclauses in described a plurality of radio-frequency channels each, if receive one or more message on channel, then Dui Ying clauses and subclauses further are included in the device ID that sends at least one device of message on the described channel;
Be used for from the logic of described channel Mapping selective channel;
Be used for during requiring the time interval, sending logic about the message of selected channel;
Be used for during requiring the time interval, receiving logic about the message of selected channel; With
Be used for determining the logic whether described equipment will begin to communicate by letter with other devices on the described channel based on characteristic about the reception message of selected channel.
9. program product according to Claim 8, the wherein said logic that is used for keeping channel Mapping further is each device ID storage power level of each clauses and subclauses of described channel Mapping, and the described channel that is used for selecting not have device ID from the logic of channel Mapping selective channel, the channel of device ID that perhaps has the power level of minimum storage.
10. equipment comprises:
The scanning logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for during described trace interval receiving the logic of message about each of described a plurality of radio-frequency channels;
Be used to keep the logic of scan table, wherein said scan table is for all have clauses and subclauses from its each device that receives message during described trace interval;
Be used to keep the logic of channel Mapping, wherein said channel Mapping all has clauses and subclauses in the described a plurality of radio-frequency channels that receive message thereon each, and each clauses and subclauses is included in the device ID that sends the device of message on the respective channels;
Be used for described channel Mapping is categorized as the logic of tlv triple channel Mapping, wherein each three continuous group of entries is relevant with three continuous channels, and wherein average power is stored in the clauses and subclauses of each channel;
Be used for by from having the tlv triple selective channel of lowest center average power, and from described tlv triple channel Mapping the logic of selective channel;
Be used for during requiring the time interval in advance, sending logic about the Preclaim message of selected channel;
Be used to receive message about selected channel, and based on the logic of each the bar information updating scan table that during requiring the time interval in advance, receives;
Be used to calculate adjacency vector and logic, the summation of all average power level of described vector sum representative on all channels;
Be used for during requiring the time interval sending logic about the Claim message of selected channel, described Claim message comprise adjacency vector and;
Be used for during requiring the time interval, receiving logic about the message of selected channel;
Be used to keep the logic of requirement table, described requirement table all has clauses and subclauses for each the device ID that sends about the message of selected channel during requiring the time interval; With
Be used for when the end that requires the time interval, estimating the logic of requirement table, wherein:
If the requirement table does not have clauses and subclauses, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel;
If described requirement table has clauses and subclauses, then described logic checks whether selected channel requires the beginning in the time interval to be occupied described, if and selected channel do not occupied in the beginning that requires the time interval, then described logic impels described equipment to turn back to scanning channel during trace interval;
If selected channel described require the time interval begin do not occupied, then described logic checks whether all table clauses that require all comprise than in the described low power level of power level that writes down before requiring the time interval on selected channel, if all table clauses that require all comprise than in the described low power level of power level that writes down on selected channel before requiring the time interval, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel; With
If any one requires table clause all to comprise than in the described high power level of power level that writes down on selected channel before requiring the time interval, then described logic comparison adjacency vector and with message therein in the adjacency vector that receives, if described adjacency vector and greater than the described adjacency vector that receives, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel, otherwise described logic impels described equipment to turn back to scanning channel during described trace interval.
11. according to the equipment of claim 10, the wherein said logic that is used to keep channel Mapping keeps sending on channel with high-average power the device ID of the device of one or more message for each clauses and subclauses.
12. equipment according to claim 11, further comprise and be used to determine during described trace interval, whether any power level that writes down in channel Mapping surpasses the logic of threshold power level, if then described logic impels described equipment to enter standby mode.
13. according to the equipment of claim 12, further comprise be used to determine described require the time interval in advance during, whether scan table comprises the logic of too many clauses and subclauses, if then described logic impels described equipment to enter standby mode.
14. a method comprises step:
The a plurality of radio-frequency channels of scanning during trace interval;
During described trace interval, receive about each the message in described a plurality of radio-frequency channels;
Keep scan table, wherein said scan table is for all have clauses and subclauses from its each device that receives message during trace interval;
Keep channel Mapping, wherein said channel Mapping all has clauses and subclauses in the described a plurality of radio-frequency channels that receive message thereon each, and each clauses and subclauses is included in the device ID that sends the device of message on the respective channels;
Described channel Mapping is categorized as the tlv triple channel Mapping, and wherein each three continuous group of entries is relevant with three continuous channels, and wherein average power is stored in the clauses and subclauses of each channel;
By selective channel from tlv triple with lowest center average power, and from the tlv triple channel Mapping selective channel;
During requiring the time interval in advance, send Preclaim message about selected channel;
Reception is about the message of selected channel, and based on each the bar information updating scan table that during requiring the time interval in advance, receives;
Calculate adjacency vector and, the summation of all average powers of wherein said vector sum representative on all channels;
During requiring the time interval, send Claim message about selected channel, described Claim message comprise adjacency vector and;
In the described message that receives during requiring the time interval about selected channel;
Keep to require table, wherein said requirement table all has clauses and subclauses for each the device ID that sends about the message of selected channel during requiring the time interval; With
Estimate the requirement table when the end that requires the time interval, wherein said evaluation procedure comprises step:
If the requirement table does not have clauses and subclauses, then impel described equipment to begin to communicate by letter with other devices by selected channel;
If described requirement table has clauses and subclauses, check then whether selected channel requires the beginning in the time interval to be occupied described, if and selected channel is then impelled described equipment to turn back to scanning channel during described trace interval not occupying in the beginning that requires the time interval;
If selected channel require the time interval begin do not occupied, check then whether all table clauses that require all comprise than in the described low power level of power level that writes down before requiring the time interval on selected channel, if all table clauses that require all comprise than in the described low power level of power level that writes down on selected channel before requiring the time interval, then impel described equipment to begin to communicate by letter with other devices by selected channel; With
If any one requires table clause all to comprise than in the described high power level of power level that writes down on selected channel before requiring the time interval, then relatively adjacency vector and with message therein in the adjacency vector that receives, if described adjacency vector and greater than the described adjacency vector that receives, then impel described equipment to begin to communicate by letter, otherwise impel described equipment to turn back to scanning channel during described trace interval with other devices by selected channel.
15. according to the method for claim 14, the wherein said step that is used to keep channel Mapping keeps sending on channel with high-average power the device ID of the device of one or more message for each clauses and subclauses.
16. method according to claim 15, further comprise and be used to determine during described trace interval, whether any power level that writes down in channel Mapping surpasses the step of threshold power level, if then described logic impels described equipment to enter standby mode.
17. according to the method for claim 15, further comprise be used to determine described require the time interval in advance during, whether scan table comprises the step of too many clauses and subclauses, if then described logic impels described equipment to enter standby mode.
18. a program product, described program product comprises computer-readable medium, has embedded in the described computer-readable medium to be used to store data computing machine program, and described computer program comprises:
The scanning logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for during described trace interval receiving the logic of message about each of described a plurality of radio-frequency channels;
Be used to keep the logic of scan table, described scan table is for all have clauses and subclauses from its each device that receives message during described trace interval;
Be used to keep the logic of channel Mapping, described channel Mapping all has clauses and subclauses in the described a plurality of radio-frequency channels that receive message thereon each, and each clauses and subclauses is included in the device ID that sends the device of message on the respective channels;
Be used for described channel Mapping is categorized as the logic of tlv triple channel Mapping, wherein each continuous three group of entries is relevant with three continuous channels, and wherein average power is stored in the clauses and subclauses of each channel;
Be used for by from having the tlv triple selective channel of lowest center average power, and from the tlv triple channel Mapping logic of selective channel;
Be used for during requiring the time interval in advance, sending logic about the Preclaim message of selected channel;
Be used to receive message about selected channel, and based on the logic at described each the bar information updating scan table that receives during requiring the time interval in advance;
Be used to calculate adjacency vector and logic, the summation of all average powers of described vector sum representative on all channels;
Be used for during requiring the time interval sending logic about the Claim message of selected channel, described Claim message comprise adjacency vector and;
Be used for the logic that receives during requiring the time interval about the message of selected channel described;
Be used to keep the logic of requirement table, described requirement table is for all having clauses and subclauses at described each device ID that sends during requiring the time interval about the message of selected channel; With
Be used for when the end that requires the time interval, estimating the logic of requirement table, wherein:
If the requirement table does not have clauses and subclauses, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel;
If described requirement table has clauses and subclauses, then described logic checks whether selected channel requires the beginning in the time interval to be occupied described, if and selected channel do not occupied in the beginning that requires the time interval, then described logic impels described equipment to turn back to scanning channel during described trace interval;
If selected channel described require the time interval begin do not occupied, then described logic checks whether all table clauses that require all comprise than in the described low power level of power level that writes down before requiring the time interval on selected channel, if all table clauses that require all comprise than in the described low power level of power level that writes down on selected channel before requiring the time interval, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel; With
If any one requires table clause all to comprise than in the described high power level of power level that writes down on selected channel before requiring the time interval, then described logic comparison adjacency vector and with message therein in the adjacency vector that receives, if described adjacency vector and greater than the described adjacency vector that receives, then described logic impels described equipment to begin to communicate by letter with other devices via selected channel, otherwise described logic impels described equipment to turn back to scanning channel during described trace interval.
19. according to the program product of claim 18, the wherein said logic that is used to keep channel Mapping keeps sending on channel with high-average power the device ID of the device of one or more message for each clauses and subclauses.
20. program product according to claim 19, further comprise and be used to determine during described trace interval, whether any power level that writes down in channel Mapping surpasses the logic of threshold power level, if then described logic impels described equipment to enter standby mode.
21. according to the program product of claim 19, further comprise be used to determine described require the time interval in advance during, whether scan table comprises the logic of too many clauses and subclauses, if then described logic impels described equipment to enter standby mode.
22. employed equipment in the access point of a wireless networking communication environment comprises:
The logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for receiving the logic of message at other access points from described a plurality of radio-frequency channels during the described trace interval;
Be used to keep the logic of channel Mapping, described channel Mapping all has clauses and subclauses for each of described a plurality of radio-frequency channels, if receive one or more message on channel, then Dui Ying clauses and subclauses further comprise for the AP-ID that sends at least one access point of message on described channel;
Be used for from the logic of channel Mapping selective channel;
Be used for during requiring the time interval, sending logic about the message of selected channel;
Be used for described require the time interval during other access points from the selected channel receive the logic of message; With
Be used for determining the logic whether described equipment will begin to communicate by letter with other wireless devices on the described channel based on characteristic about the reception message of selected channel.
23. equipment according to claim 22, the wherein said logic that is used for keeping channel Mapping further is each AP-ID storage power level of each clauses and subclauses of described channel Mapping, and the described channel that is used for selecting not have from the logic of channel Mapping selective channel AP-ID perhaps selects to have the channel of AP-ID of the power level of minimum storage.
24. according to the equipment of claim 23, the wherein said characteristic that is used for based on the message that on selected channel, receives, determine that the logic whether described equipment will begin to communicate by letter with other wireless devices on the described selective channel comprises:
Be used to estimate the logic of the power level of the message that on selected channel, receives, if the power level of the message that receives on selected channel is lower than threshold value, the then described logic that is used to determine indicates described equipment to begin to communicate by letter with other wireless devices on selected channel.
25. employed method in the access point of a wireless networking communication environment, described method comprises step:
The a plurality of radio-frequency channels of scanning during trace interval;
Receive message at other access points from described a plurality of radio-frequency channels during the described trace interval;
Keep channel Mapping, wherein said channel Mapping all has clauses and subclauses for each of described a plurality of radio-frequency channels, if receive one or more message on channel, then Dui Ying clauses and subclauses further comprise for the AP-ID that sends at least one access point of message on described channel;
Selective channel from described channel Mapping;
During requiring the time interval, send message about selected channel;
Described require the time interval during other access points from the selected channel receive message; With
Based on the characteristic of the message that on selected channel, receives, determine whether described equipment will begin to communicate by letter with other wireless devices on the described channel.
26. method according to claim 25, the wherein said step that is used for keeping channel Mapping further is included as the step of each AP-ID storage power level of each clauses and subclauses of described channel Mapping, and the described channel that is used for selecting not have from the step of channel Mapping selective channel AP-ID perhaps selects to have the channel of AP-ID of the power level of minimum storage.
27. according to the method for claim 26, the wherein said characteristic that is used for based on the message that on selected channel, receives, determine that the step whether described equipment will begin to communicate by letter with other wireless devices on the described selective channel comprises step:
The power level of the message that evaluation receives on selected channel, if the power level of the message that receives on selected channel is lower than threshold value, the then described step that is used to determine indicates described equipment to begin to communicate by letter with other wireless devices on selected channel.
28. program product, described program product comprises computer-readable medium, embedded in the described computer-readable medium and be used to store data computing machine program, described computer program is used by the access point in the wireless networking communication environment, and described computer program comprises:
The logic that is used for a plurality of radio-frequency channels of scanning during trace interval;
Be used for receiving the logic of message at other access points from described a plurality of radio-frequency channels during the described trace interval;
Be used to keep the logic of channel Mapping, described channel Mapping all has clauses and subclauses in described a plurality of radio-frequency channels each, if receive one or more message on channel, then Dui Ying clauses and subclauses further comprise for the AP-ID that sends at least one access point of message on described channel;
Be used for from the logic of channel Mapping selective channel;
Be used for during requiring the time interval, sending logic about the message of selected channel;
Be used for described require the time interval during other access points from the selected channel receive the logic of message; With
Be used for determining the logic whether described equipment will begin to communicate by letter with other wireless devices on the described channel based on characteristic about the reception message of selected channel.
29. program product according to claim 28, the wherein said logic that is used for keeping channel Mapping further is included as each AP-ID storage power level of each clauses and subclauses of described channel Mapping, and the described channel that is used for selecting not have from the logic of channel Mapping selective channel AP-ID perhaps selects to have the channel of AP-ID of the power level of minimum storage.
30. according to the program product of claim 29, the wherein said characteristic that is used for based on the message that on selected channel, receives, determine that the logic whether described equipment will begin to communicate by letter with other wireless devices on the described selective channel comprises:
Be used to estimate the logic of the power level of the message that on selected channel, receives, if the power level of the message that receives on selected channel is lower than threshold value, the then described logic that is used to determine indicates described equipment to begin to communicate by letter with other wireless devices on selected channel.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US44960203P | 2003-02-24 | 2003-02-24 | |
| US60/449,602 | 2003-02-24 | ||
| US60/466,448 | 2003-04-29 | ||
| US60/472,320 | 2003-05-21 | ||
| US60/472,239 | 2003-05-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1778124A true CN1778124A (en) | 2006-05-24 |
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ID=36766724
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200480010879 Pending CN1778124A (en) | 2003-02-24 | 2004-02-18 | System and method for power adjustment in a wireless network. |
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| Country | Link |
|---|---|
| CN (1) | CN1778124A (en) |
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| CN102378218A (en) * | 2011-11-04 | 2012-03-14 | 中国联合网络通信集团有限公司 | Access point equipment of wireless local area network and channel selection method thereof |
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| CN103379549A (en) * | 2012-04-20 | 2013-10-30 | 北京新岸线移动多媒体技术有限公司 | Data transmission method, system and device in wireless network |
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