CN1857016A - Wireless communication method and apparatus for optimizing access point channel selection - Google Patents

Abstract

A startup process of an access point (AP) includes a discovery phase and an announcement phase. During the discovery phase, the AP detects neighboring APs from its own extended service set (ESS), neighboring APs from different ESSs, and external sources of interference. During the announcement phase, the AP transmits its beacon signals at maximum power in order to accelerate recognition by neighboring APs running the discovery phase. An automatic initialization channel selection process of an AP scans channels the AP will use to communicate. Information of each scanned channel is recorded and a best performance channel is determined for use by the AP.

Description

Carry out radio communication method and the device of access point starting and preliminary channel selection process

Technical field

The present invention is about a kind of wireless communication system. More specific speech, the present invention is about being an access point (AP) initialization operation parameter and selecting the most appropriate operation channel.

Background technology

The condition of the one radio link at one wireless communication system running place may change at any time. Because a wireless transmission/reception unit (WTRU) takes action, this WTRU may break away from calmly on its position or in the scope of one or more APs. When an AP just be established or because some former the shutdown after again the start, the starting process of this AP must be assessed its radio resource environment. Generally speaking, starting process also provides one to be used for to the own mechanism that occurs of other APs announcement of its own Extension Services collection (ESS) so that other APs accordingly the oneself adjust the operating parameter of having by oneself.

There are now several frameworks to be used to improve the capacity of wireless communication system. It is that these frameworks are wherein a kind of that channel (that is frequency) is selected, and uses to allow one or more interior APs of a network select the relevant WTRUs contact with other of one or more channel. The coordination of AP channel selection generally is to carry out with manual mode. But it be very unpractical coordinating channel selection with manual mode in response to each the little variation in the network configuration, because this may cause the redesign of all APs and configuration again. The problem that unauthorized frequency spectrum and external interference source also can cause manual coordination fully to solve. In addition, be difficult to channel be assigned into meeting so that the traffic load of adjacent APs is shared in available channel in the mode of a maximization total system capacity by manual channel selection mode.

Known framework have that a plurality of APs attempt to start shooting simultaneously the time can meet with another problem. This situation occurs in a network, and all APs attempt making a channel selection at same time. Therefore, the channel selection of APs can not be best, does not include in and considers because each AP will be close to the channel selection of APs.

The method and system that overcome aforementioned problem can be very favourable.

Summary of the invention

The present invention proposes the starting of a kind of implementation one AP and method and the device of preliminary channel selection process.

The starting process of this AP comprises path forfeiture and finds step and an announcement step. During step was found in the forfeiture of this path, this AP detected from the contiguous APs of its own ESS, from the contiguous APs of different ESSs, reaches external interference source. During this announcement step, this AP launches a beacon signal and is just found that in the operating path forfeiture the contiguous APs of step recognizes in order to accelerate. This starting process provides monitoring to this AP and assesses the ability of its radio environment, thereby allows that this AP oneself determines preliminary operating parameter.

A kind of AP initializes the channel selection process and automatically carries out when the starting process of this AP begins.

Description of drawings

We can be from proposing with way of example and should more understand for the present invention together with the appended graphic following detailed description of being understood, graphic in:

Fig. 1 is a block diagram according to a wireless communication system of the present invention;

Fig. 2 is a flow chart according to the AP starting process of one embodiment of the invention;

Fig. 3 is a flow chart according to the automatic channel selection process of another embodiment of the present invention; And

Fig. 4 one initializes the flow chart of channel selection process according to one of another embodiment of the present invention.

The specific embodiment

Hereinafter, the non-limitation of term " WTRU " comprises the device of user's equipment (UE), an action station, fixing or action subscriber unit, calling set or any type that other can operate in a wireless environment.

Hereinafter, the non-limitation of term " AP " comprises wireless environment Jie connection device of an access point, a base station, B node, site controller or any other type.

Feature of the present invention can be merged in the IC or be configured in one and comprise in the circuit of a plurality of interconnecting assemblies.

As described below, the present invention can be applicable to WLAN network (WLAN) technology substantially, for example be applied to substantially IEEE 802.11 and ETSI HyperLAN specification, so can infer and it is applied in other restriction disturbs wireless system such as IEEE 802.15 and IEEE 802.16.

Fig. 1 is a block diagram according to wireless communication system 100 of the present invention. Wireless communication system 100 comprises an AP 105 and a plurality of WTRUs 110a-110n. AP 105 sees through a wireless link 115 and WTRUs 110a-110n contact via an antenna 120. AP 105 comprises a transceiver 125, a channel selector 130, a measuring unit 135, a power controller 140, a timer 145 and an internal memory 150. Transceiver 125 sends signal 115a-115n and receives signal 115a-115n from described WTRUs via 120 couples of WTRUs 110a-110n of antenna.

Channel selector 130 is selected a channel that is used for each WTRU 110a-110n contact. Measuring unit 135 is measured the operating parameter of supporting AP 105. Measuring unit 135 is responsible for collecting, processing and the storage of channel measuring value, the non-limitation of these measuring values comprises: channel utilization rate (that is the busy time percentage of channel), the position that disturb outside (non-802.11) is accurate, the received signal strength that records from receiving package, and similar measuring value. The through-put power of power controller 140 control AP 105. Timer 145 is set one or more predetermined period that AP 105 carries out some operation. Internal memory 150 comprises the data of record such as measurement result for AP 105 provides storage capacity.

Fig. 2 is the flow chart of the starting process 200 of an AP 105, and this process comprises one and finds step 210 and an announcement step 220. In finding step 210, AP 105 initializes it and measures parameter and numerical value (step 211). The measurement parameter that is initialised and numerical value can comprise 1 interior parameter and the numerical value that is listed in the table below for instance. As have the knack of this skill person and can understand, can more use other parameter and numerical value or replace with other parameter and numerical value at these parameters and numerical value outer.

Symbol	Describe	Type	Default value
				ACS	The set of tolerable channel	Configuration parameters	{1，6，11   }
T mpp_fix Dis cover	Produce the discovery step value of the fixed component at interval quiet measuring period	Configuration parameters	1000 milliseconds
				T mpp_var Dis cover	Produce the discovery step value of amplitude of the variable componenent at interval quiet measuring period	Configuration parameters	0 millisecond
T mpp_dur Dis cover	The discovery step value of the duration of one quiet measuring period	Configuration parameters	1000 milliseconds
				N MIN_MS Dis cover	The minimum number of the measuring assembly during the discovery step	Configuration parameters	4
N MAX_MS Dis cover	The maximum quantity of the measuring assembly during the discovery step	Configuration parameters	15
				T dur Announce	The announcement step duration	Configuration parameters	10 seconds
T beacon Announce	Beacon transmission cycle during the announcement step	Configuration parameters	100 milliseconds
				P max	Maximum AP through-put power	Configuration parameters	20dBm

Table 1

In the step 212 of finding step 210, measuring unit 135 is to carry out N_{meas_sets} ^Dis coverThe mode of measuring assembly is measured operating parameter, sequentially obtains by this measuring value in a period of time that each channel in the tolerable channel set (ACS) is comprised of the complete circulation of the measuring period of implementing all channels in this ACS during a measuring assembly. For instance, operating parameter can be through-put power and the channel setting value of AP 105. Better, the measurement duration of the integral body on each channel (is equivalent to T_{mpp_fix} ^Dis cover×N ^Dis cover) set for and can receive enough strong package from contiguous APs. Strong package is sent to improve the package that it is close to the possibility that APs detects by an AP with peak power.

T _{mpp_fix} ^Dis coverDuration be configured to be long enough to limit edge effect, this edge effect system occurs in a package and is between the tour between measuring period (MPs) in the transmission in the state. Again, better for T_{mpp_fix} ^Dis coverSet for to be short to and be enough to allow rotating continuously so that AP 105 can detect a contiguous APs channel of one wherein changes between channel. This duration and described periodic system are determined by timer 145. Find that the duration of step 210 is by being evenly distributed on N_{MIN_MS} ^Dis coverWith N_{MAX_MS} ^Dis coverBetween any a plurality of measuring assemblies form. The duration of finding step 210 is arbitrarily, uses and considers the situation that two or more APs start shooting simultaneously, avoids these APs to carry out preliminary channel selection at same time.

Because these measurements, AP 105 is judged its radio environment, for example from the detection of the contiguous APs of its own ESS, from the detection of the contiguous APs of different ESSs, reach the detection of external interference source.

Later with reference to figure 2, in case finish N_{meas_sets} ^Dis coverUsefulness measuring assembly (step 212), the power control (step 213) of power controller 140 priming AP 105. Power control determines a baseline scope and the dependency basis linear heat generation rate setting value of AP 105. In the control of the power of AP 105 after step 213 priming, the channel of channel selector 130 primings one channel optimization process (step 214) to select a specific AP or APs network to use. The preliminary channel setting value of AP 105 is to determine as the basis take the parameter that is determined by power controller 140.

During finding step 210, AP 105 keeps quiet (that is AP 105 does not send any package). After finding that step 210 is finished, AP 105 has collected enough information and has decided an optimum operation channel and select through-put power setting value.

Finding after step 210 finishes it is an announcement step 220. During announcement step 220, AP becomes its operation channel configuration the best channel that determines when finding that step 210 finishes. It will be appreciated that and optionally during transition to carry out other process. The purpose of announcement step 220 is to accelerate AP to be detected by its contiguous APs. In announcement step 220 when beginning, each parameter (T for example_dur ^Announce、T _beacon ^Announce、P _MAX) (step 221) is initialised. In announcement step duration T_dur ^AnnounceDuring this time, AP 105 is only with cycle T_beacon ^AnnounceSend and have a maximum through-put power P_MAXBeacon frame (step 222). This accelerates AP 105 and is detected by other APs, because only send the peak power package. During announcement step 220, the covering the extraneous WTRUs of ripple and may attempt contacting with AP 105 of AP 105, because AP 105 is just with its peak power P_maxEmission. Therefore event can refusal during announcement step 220 be related from the institute of WTRUs and be asked to avoid relating to for a moment WTRU of disengaging scope during normal operating.

In case announcement step 220 finishes, the starting of AP 105 is namely finished. Then AP 105 becomes himself configuration for its normal operating (step 223) and begins normal operating (step 230). AP 105 sets its through-put power for determined by power controller 140 setting value, accepts contact request from WTRUs 110 in this rear AP 105 beginning normal operatings and beginning.

Fig. 3 is a flow chart according to the auto-initiation channel selection process 300 of one embodiment of the invention. In this preferred embodiment, this channel selection process by priming, has obtained the measuring value on each channel this moment when finding that step 210 finishes. Select for a specific AP or the channel of an APs network. Channel selection must be for finishing with manual mode or automated manner, and must be for just beginning to carry out or dynamically carry out in operation when disposing. The present invention's WLAN network (WLAN) of can arranging in pairs or groups is used (for example according to IEEE 802.11) and is carried out.

Initializing channel selection process 300 ties up to and carries out during the starting process 200 and determine the optimum operation channel. In preferred embodiment, channel is scanned during discovery step 210. When finding that step 210 finishes, the channel selection process is selected best channel take the measuring value that foundation observes with regard to each channel as the basis by priming during finding step 210 in step 214. In all situations, initialize the channel selection process 300 a plurality of channels of scanning (for example channel 1-11) to detect available best channel. The sequence that is scanned channel can be according to a predefined procedure, and perhaps it can be at random. The channel sequence not necessarily will comprise all available channels. Be scanned channel for each, this process is judged: 1) have which other APs to operate at this channel; 2) the described APs part (that is according to ESS) of same system whether; 3) signal strength signal intensity of described APs; 4) the traffic amount on this channel; And 5) whether any other interference source (for example non-802.11 disturbing) is arranged on this channel, and the non-WLAN jamming power position of receiving is accurate. After scanning was finished, which channel AP can calculate can obtain best efficiency (channel that for example has minimum interference). Then AP will oneself retune into this channel. Described other APs that inspection measures whether same system a part and decide, AP can determine for the selection of using channel more positive or more not positive.

In an alternate embodiment, coordinate frequency and select and to finish in the following manner: 1) make APs mutually exchange the information of relevant its speciality (for example load, capacity or position); Or 2) have one can obtain information and set the centralized architecture of the channel of all APs in the network from each AP. With regard to the first situation, each AP still can independently make decision, but the information of exchange can allow one better to determine (for example its can comprise be difficult to by another AP from external observation to statistics). With regard to the second situation, to collect information and notify a centralized unit or device with these information from different APs, this centralized unit is made a decision and is later notified different APs with this decision after receiving information.

Still with reference to Fig. 3, when initializing 300 beginnings (step 305) of channel selection process, allow AP 105 all channels of scanning with identity and the received signal strength indicator (RSSI) (step 310) of near all APs detecting. In preferred embodiment, step 310 can be during finding step 210 and carries out. In step 315, the tabulation of scanning channel. All or part of of tabular channel can be according to a predetermined or random sequence and sequentially is scanned. The information (step 320) relevant with each AP that record detects with regard to each channel. This information can be including (but not limited to) in the identity that is scanned other APs that channel operates, and other APs is the indication of the part of same ESS whether, the signal strength signal intensity of APs, and the traffic amount on the channel, and whether any other interference source is arranged on the channel.

After scanning was finished, AP 105 judged which channel provides best efficiency (step 325). For instance, this may be to judge by measuring which channel mode that to have minimum interference or no other APs be the part of same ESS. In case judge the channel with best efficiency, AP 105 will oneself be tuned to this best channel.

Fig. 4 one is used for determining the detail flowchart of the initialization channel selection process 400 of best channel according to another embodiment of the present invention after AP starting. Initialize channel selection process 400 and comprise candidate's channel decision process 405 and a channel selection process 450.

In candidate's channel decision process 405, AP 105 retrieval maximums are allowed interference I_MAX(step 410), it is for allowing interference take the baseline scope of an AP as the maximum that the basis determines on any known channel. I_MAXCan obtain from power control process. Imax system utilizes equation (1) to calculate by initializing channel selection process 400. The parameter some of them parameter of using in the equation (1) is to obtain from the power control process retrieval. In particular, power control can determine RNG_base On the other hand, P_max、(C/I) _{req_hig}And M_IIt is the parameter that predetermines. Better, for the I of candidate's channel decision process 405_MAXSystem calculates according to equation (1):

   I _MAX＝P _max-RNG _base-(C/I) _{req_high}-M _IEquation (1)

P wherein_maxIt is the maximum through-put power of AP 105; RNG_baseIt is the scope that AP 105 covers; And (C/I)_{req_high}It is the necessary carrier power interference ratio of a two-forty package (for example 11Mbps). M_IThat an elimination channel possesses a possible enough and to spare of too allowing the interference level that the position is accurate near actual maximum. Another selects the predetermined I who is used to determine the tabulation of candidate's channel that is worthwhile for of Imax_MAX。

Select one first channel (step 415) from an ACS. Measure the interference I of a channel and allow interference I with itself and maximum_MAXCompare (step 420). If allowing less than maximum, the interference I of this channel disturbs I_MAX, then AP 105 charges to a candidate list (step 425) in the internal memory 150 with this channel. If disturbing I to be not less than maximum, this channel allows interference I_MAX, then AP 105 checks in the ACS whether also have any channel to have (step 430). If still there is channel to exist in the ACS, then AP 105 selects next channel (step 435) and candidate's channel decision process 405 is got back to step 420 from ACS.

If no longer include channel in the ACS, then AP 105 checks whether any available candidate channel (step 440) is arranged. If judging in step 440 does not have the available candidate channel, then AP 105 is with I_MAXIncrease Δ dB (step 445) and candidate's channel decision process 405 and get back to step 415. If judge to have at least candidate's channel to exist in step 440, then candidate's channel decision process 405 is finished, and then carries out channel selection process 450.

Channel selection process 450 used standards are quantity N of the contiguous BSSs that records at each channel_B(k). In case select candidate's channel, judge in the middle of all candidate's channels the minimum number N that records beacon from different B SSs_B ^Min(step 455). The quantity of the contiguous BSSs that records at channel k is N_B(k) and the minimum number that records BSSs be N_B ^MinCondition under, from candidate's channel tabulation, remove N_B(k)＞N _B ^MinAll channels (step 460). In other words, the channel that only possesses the minimum BSSs of recording is left. Another selection, in step 455 and 460, the quantity that records contiguous BSSs on each channel can be replaced by the channel utilization rate on each channel. Channel utilization rate measuring value is equivalent to receiver by the time percentage of WLAN signal carrier locking. In this case, channel selection process meeting preference has the channel than the low channel utilization rate.

Another used standard of channel selection process is that minimum records interference level, and this is to determine (step 465) with all remaining candidate's channels. Record interference level I (k) and minimum interference level I with the minimum on the channel k_MINCompare, and from the tabulation of candidate's channel, remove I (k)＞I_MINAll channels (step 470). In other words, the channel that only possesses minimum interference level is left.

If have the accurate candidate's channel in minimum power position more than to exist, then in the middle of remaining candidate's channel, select at random a channel (step 475).

The example parameter that initializes channel selection process 400 is listed in the table below in 2. Haveing the knack of this skill person will appreciate that and can more use other parameter and numerical value or replace with other parameter and numerical value outside these parameters and numerical value.

Symbol	Describe	Type	Default value
				ACS	The set of tolerable channel	Configuration parameters	{1，6，11}
N B(k)	The quantity of the contiguous BSSs that records at channel k. Utilize the minimum of a value of EDT to detect contiguous beacon frame.	Measuring value	Nothing
				I(k)	The interference that records at channel k. I is measured as the average received signal power when not being received device " carrier lock " (that is receiver does not receive any package).	Measuring value	Nothing

RNG base	Baseline scope (being set by path forfeiture discovery procedure)	Inner parameter	Nothing
				(C/I) req	Support the minimum necessary carrier power interference ratio of peak data transfer rate	Configuration parameters	10dB
P max	Maximum AP through-put power	Configuration parameters	20dBm
				I MAX	Allow interference take the baseline scope as the maximum that the basis determines on any known channel	Inner parameter	Nothing
M I	Be used to maximum and allow interference level IMAXThe interference enough and to spare of calculating	Configuration parameters	3dB
				Δ	There is not I＜IMAXCandidate's channel the time maximum is allowed disturb IMAXThe amount that increases, the dB of unit.	Configuration parameters	3dB

Table 2

Although with regard to specific combination feature of the present invention and assembly are described in preferred embodiment, each feature or assembly must be used alone or use with the multiple combinations that is with or without further feature of the present invention and assembly.

Claims (29)

1. the method for the selection of optimization channel that this AP uses in comprising at least one access point (AP) and a wireless communication system that a plurality of wireless transmission/reception units (WTRU) are communicated by letter, the method may further comprise the steps:

(a) determine to be used for candidate's channel that support is communicated by this AP; And

(b) select a channel in the middle of described candidate's channel as the basis take a specific standard, wherein step (a) and (b) automatically carry out after tying up to this AP of priming.

2. method according to claim 1 is characterized in that, described candidate's channel system records from tolerable channel set (ACS) take one of each candidate's channel to disturb and determined less than one that maximum allows to disturb as condition and select.

3. method according to claim 1 is characterized in that, step (b) more comprises:

(b1) a beacon minimum number after testing that determines that described candidate's channel detects; And

(b2) in the middle of described candidate's channel, select one to possess this after testing channel of beacon minimum number.

4. method according to claim 1 is characterized in that, step (b) more comprises:

(b1) determine the minimum interference level that described candidate's channel receives; And

(b2) select a channel that possesses this minimum interference level in the middle of described candidate's channel.

5. method according to claim 1 is characterized in that, selects randomly a channel at least when step (b) more has been included in two selection channels.

6. one kind is used for the access point (AP) communicate by letter with a plurality of wireless transmission/reception units (WTRUs) in a wireless communication system, and this AP comprises:

(a) measuring unit, it is used for measuring the measurement operating parameter of each channel in the tolerable channel set (ACS) after this AP priming;

(b) power controller, it is used for take the through-put power of described operating parameter as this AP of base control;

(c) channel selector, it is used for selecting a channel that supplies this AP to communicate as the basis take the described operating parameter that records;

(d) timer, it is used for cycle time of setting, and a beacon frame sent in order to announce described operating parameter to other APs from this AP within this cycle; And

(e) internal memory, it is used for storing the described operating parameter that records.

7. AP according to claim 6 is characterized in that, this beacon frame ties up in this time cycle and is transferred to other APs with its peak power.

8. AP according to claim 6 is characterized in that, the interference level of described candidate's channel system from tolerable channel set (ACS) take described candidate's channel allowed to disturb as condition less than a maximum on the channel and selected.

9. method of starting the access point (AP) of wireless communication system, the method comprises:

(a) behind this AP of priming, obtain the operating parameter of this AP;

(b) carry out the preliminary operation of this AP as the basis take described operating parameter; And

(c) announce the operating parameter of this AP to other APs.

10. method according to claim 9 is characterized in that, step (a) more comprises:

(a1) initialize the operating parameter of this AP; And

(a2) in a predetermined period of time, measure described operating parameter.

11. method according to claim 9 is characterized in that, step (b) more comprises:

(b1) carry out the power control of this AP as the basis take the measuring value of described operating parameter; And

(b2) be controlled to be the basis with this power and carry out a channel selection.

12. method according to claim 9 is characterized in that, step (b) is to carry out in the mode that its maximum through-put power sends beacon frame in a predetermined period of time with this AP.

13. automatically select the method for the preliminary channel of a specific AP for one kind in a wireless communication system that comprises a plurality of access points (APs), the method comprises:

(a) scan a plurality of channels that this AP will be used for communicating;

(b) record with whenever once scanning the relevant information of a AP that channel detects; And

(c) select take this recorded information as the basis described in the middle of the scanning channel channel with best efficiency.

14. method according to claim 13, it is characterized in that this recorded information comprises in the middle of the following information one or many persons: an indication, and other APs part of same Extension Services collection (ESS) whether that whether other APs running is arranged on the traffic amount on a signal strength signal intensity of this channel, this channel, the interference source on this channel, this channel.

15. an access point (AP) comprises:

(a) one obtain member, be used for obtaining the operating parameter during priming of this AP;

(b) one carry out member, be used for take the preliminary operation of described operating parameter as this AP of basis execution; And

(c) an announcement member is used for announcing to other APs the operating parameter of this AP.

16. AP according to claim 15 is characterized in that, this is obtained member and more comprises:

(a1) be used for initializing the member of the operating parameter of this AP; And

(a2) be used in a predetermined period of time measuring the member of described operating parameter.

17. AP according to claim 15 is characterized in that, this execution member more comprises:

(b1) be used for carrying out as the basis take measuring value the member of the power control of this AP; And

(b2) be used for the member that carries out a channel selection as the basis take the result of this power control.

18. an access point (AP) comprises:

(a) with the member that decides for candidate's channel of the communication of supporting to be undertaken by this AP; And

(b) be used for selecting in the middle of described candidate's channel as the basis take a specific standard member of a channel, wherein step (a) and (b) automatically carry out after tying up to this AP priming.

19. AP according to claim 18 is characterized in that, this channel selection member comprises:

(b1) with the member of beacon minimum number after testing that decides that described candidate's channel detects; And

(b2) be used in the middle of described candidate's channel, selecting one to possess this after testing member of the channel of beacon minimum number.

20. an access point (AP) that is used for selecting from candidate's channel tabulation a channel, this AP comprises:

(a) with deciding relevant with described candidate's channel one member of beacon minimum number after testing; And

(b) be used for selecting one or more to possess this after testing member of the channel of beacon minimum number from this tabulation.

21. AP according to claim 20, it more comprises:

(c) with the member that decides the central minimum interference level of described selection channel; And

(d) be used for selecting at least one member that possesses the channel of this minimum interference level from this tabulation.

22. AP according to claim 21, it more comprises:

(e) be used for when having at least two to select channel, selecting randomly the member of a channel.

23. an integrated circuit (IC) that is used for selecting from candidate's channel tabulation a channel, this IC comprises:

(a) with deciding relevant with described candidate's channel one member of beacon minimum number after testing; And

(b) be used for selecting one or more to possess this after testing member of the channel of beacon minimum number from this tabulation.

24. IC according to claim 23, it more comprises:

(c) with the member that decides the central minimum interference level of described selection channel; And

(d) be used for selecting a member that possesses the channel of the minimum interference level in the middle of described candidate's channel from this tabulation.

25. IC according to claim 24, it more comprises:

(e) be used for when having at least two to select channel, selecting randomly the member of a channel.

26. an access point (AP) that is used for selecting from candidate's channel tabulation a channel, this AP comprises:

(a) be used in the middle of the channel that possesses a predetermined after testing beacon minimum number, determining the member of a minimum interference level; And

(b) be used for selecting a member that possesses the channel of the minimum interference level in the middle of described candidate's channel in this tabulation.

27. access point according to claim 26 (AP), it more comprises:

(c) be used for when having at least two to select channel, selecting randomly the member of a channel.

28. an integrated circuit (IC) that is used for selecting from candidate's channel tabulation a channel, this IC comprises:

(a) be used in the middle of the channel that possesses a predetermined after testing beacon minimum number, determining the member of a minimum interference level; And

(b) be used for selecting a member that possesses the channel of minimum interference level in the middle of described candidate's channel in this tabulation.

29. IC according to claim 28, it more comprises:

(c) be used for when having at least two to select channel, selecting randomly the member of a channel.

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