CN101263685A - Wireless communication terminal and network side communication equipment - Google Patents

Abstract

The disclosed techniques are used to obtain fast and reliable handovers. According to this technology, in a network configuration in which the network coverage area of the cellular base station 105 and the network coverage area of a plurality of WLAN APs (Wireless LAN Access Points) 110, 115, 120, 125, and 130 overlap, a roaming mobile node (mobile terminal) 100 stores information monitored from each WLAN AP. When handover to a new WLAN AP is determined, by obtaining the beacon information of the WLAN AP that is the handover target from the stored information, the mobile node can quickly perform the handover process without waiting to listen to the next beacon. Furthermore, the mobile node may store information on the stability of the network connection if the mobile node is to be connected to each WLAN AP, and determine which WLAN AP is a suitable handover target by considering the stability.

Description

Wireless communication terminal and network side communication equipment

technical field

The present invention relates to a wireless communication terminal (also referred to as a mobile terminal or mobile node) and a network-side communication device for communication in a packet-switched data communication network. More specifically, it relates to a wireless communication terminal and a network-side communication device having multiple access interfaces of different types.

Background technique

Mobile computing, which includes accessing the Internet while on the move, is becoming more prevalent today. Handheld phones are increasing in functionality and use of wireless LANs, and the Internet is growing. Currently, more and more portable terminals have the ability to connect to the Internet using a wide range of access technologies, such as third-generation (3G) cellular networks, general packet radio service (GPRS), IEEE 802.11a/ b/g and bluetooth. Mobility means that network connectivity is available even when nodes are moving.

Various portable computing devices with enhanced network capabilities, such as handheld mobile phones, laptop computers and personal digital assistants (PDAs), have increased the demand for seamless communication in both wired and wireless networks. The increased use of multimedia content, such as video conferencing, has made seamless communication an essential and desired feature in mobile connectivity. Practical mobility management should provide seamless handovers, where no interruption of communication is observed by the user. Today's mobile data networks typically consist of several wireless overlapping networks supporting different data rates and geographic coverage, and are only accessible via a medium-specific air interface.

Whenever a mobile node changes cells, subnets or networks, the coverage responsibility has to be switched between the various serving access nodes. In order to provide seamless roaming in these heterogeneous networks, mobile nodes must be able to connect to various access networks. In addition, a fully mutually agreed-upon global mobile communication network structure needs to manage huge mobile volumes. At the same time, portable information terminals (multi-mode nodes) with multiple access interfaces have begun to appear through the wide range of wireless access technologies available. These include dual-mode handsets, laptops and personal digital assistants.

The usefulness of connecting to the Internet using different access technologies at different times or even simultaneously has been described in various documents. However, the protocols embedded in the multimode nodes available in today's consumer market do not provide seamless switching between heterogeneous interfaces. There are also some issues to be solved when seamlessly switching between heterogeneous interfaces. Due to the diversity of overlapping available wireless networks, the considered network availability may be temporary or stable from the perspective of the mobile node.

For example, when a mobile node roams along the edge of a wireless network, the temporary nature of network coverage can cause spurious and unnecessary handoffs between network and media interfaces, even if it does not ensure stability in actual use. The overhead incurred in such handovers would disrupt the user experience and place unnecessary load on the network.

One solution of the following patent document 1 proposes a scheme to support service resumption when a mobile terminal roams within the coverage area of a wireless network by triggering local or global services. Global services can be continued while maintaining contact with the same server via different gateways.

Another solution of the following patent document 2 uses a mobile switching center in the network to send duplicate frames to roaming mobile terminals with synchronized timing in order to affect soft handover. Duplicate frames sent from the terminal are also processed and removed by the mobile switching center.

Furthermore, another solution of the following Patent Document 3 proposes a cellular timing receiver installed in a wireless LAN access point so that the cellular network and the wireless LAN are synchronized so that soft handover can be performed.

[Patent Document 1] U.S. Patent Publication 20030112789A1

[Patent Document 2] U.S. Patent Publication 20040213279A1

[Patent Document 3] U.S. Patent Publication 20030030101A1

However, the above-mentioned solution disclosed in Patent Document 1 does not optimize the handover process and also suffers from the previously described edge roaming problem. However, the above-mentioned solution disclosed in Patent Document 2 cannot work across heterogeneous networks, especially if the networks belong to different management domains or service providers. However, the above-mentioned solution disclosed in Patent Document 3 would require the participating cellular and wireless LAN networks to be synchronized, thereby reducing the overall user capacity. Furthermore, as in the case of the solution disclosed in Patent Document 2 above, there may also be problems in implementing the solution across different management areas.

The above prior art can be summarized as follows.

• Mobile terminals cannot maintain seamless connectivity, especially when handovers are performed across heterogeneous networks.

• It is difficult for a mobile terminal to determine whether the access network is temporary or stable in order to perform an efficient handover of the entire network.

• The edge roaming problem arises causing unnecessary handovers, especially when the mobile node roams along the edge of network coverage.

Contents of the invention

Accordingly, an object of the present invention is to provide a wireless communication terminal capable of obtaining fast interface switching for seamless handover and/or performing efficient handover without unnecessary handover, and capable of improving the wireless communication terminal. Stability of communication (in particular, link connection); and network-side communication equipment.

In order to achieve the purpose of the present invention, the present invention provides a wireless communication terminal comprising:

a plurality of wireless communication interface components, each of the plurality of wireless communication interface components being connectable to one or more base stations,

a beacon information storage section for storing information included in a beacon signal, wherein the beacon is periodically transmitted from the base station and received by each of the plurality of wireless communication interface sections Signal,

beacon information retrieval means for retrieving information included in a beacon signal from said beacon information storage means, according to a predetermined trigger received by a wireless communication interface means corresponding to said predetermined trigger beacon signals, and

communication control means for controlling initiation of communication on said wireless communication interface means using information included in a beacon signal retrieved by said beacon information retrieval means.

According to this structure, it is possible to obtain fast interface switching for seamless handover.

Furthermore, in addition to the above-mentioned structure, the wireless communication terminal further includes communication switching control means for when communication is started on any one of the plurality of wireless communication interface parts, or when communication is started on any one of the plurality of wireless communication interface parts When the point of attachment is switched on any one of , a predetermined trigger is provided to the beacon information retrieval section, wherein the predetermined trigger corresponds to the wireless communication interface section starting communication or switching the base station to be connected.

According to this configuration, once communication is started via the wireless communication interface, or once handover processing is performed, it is possible to obtain fast interface switching by retrieving previously stored information.

Furthermore, in addition to the above-mentioned structure, the wireless communication terminal of the present invention further includes information storage control means for switching timing of connecting to a base station on the wireless communication interface based on the start timing of communication on the wireless communication interface , and policies regarding electric power to control monitoring of beacon signals regarding said wireless communication interface, or storing information included in beacon signals into beacon information storage means.

According to this structure, it is possible to store information included in a beacon signal based on a schedule used as communication start or switching timing, or the ability to store and save electric power.

In addition, in addition to the above-mentioned structure, the wireless communication terminal of the present invention also includes:

Stability information storage means for storing information on the stability of communication with a base station to which each of said plurality of wireless communication interface means is connectable, and

Stability determination means for determining whether or not the base station can be selected as a candidate for communication based on the information on stability stored in the stability information storage means.

According to this structure, it is possible to obtain fast interface switching for seamless handover, and to perform efficient handover without unnecessary handover.

In addition, in addition to the above-mentioned structure, the wireless communication terminal of the present invention further includes a stability evaluation part for based on a beacon signal received from a base station through each of the plurality of wireless communication interface parts, or based on Information on stability of communication between a wireless communication terminal and a base station evaluates stability of communication between each of said plurality of wireless communication interface parts and a base station, wherein said information is notified from said other wireless communication terminal.

According to this configuration, it is possible for a wireless communication terminal to evaluate the stability of communication with the base station based on a beacon signal received from the base station or information on the stability of communication with the base station exchanged with other wireless communication terminals.

Furthermore, in addition to the above-mentioned structure, in the wireless communication terminal of the present invention, the stability evaluation section is arranged to: Sort base stations.

According to this structure, it is possible for a wireless communication terminal to rank the stability of communication with each base station.

In addition, in addition to the above-mentioned structure, the wireless communication terminal of the present invention also includes:

Stability information storage means for storing information on the stability of communication with a base station to which each of said plurality of wireless communication interface means is connectable, and

a message sending section for sending a message requesting improvement of stability of communication to a base station whose stability becomes lower than a predetermined threshold level by referring to information on stability stored in said stability information storage section.

According to this structure, it is possible to improve the stability of communication of the wireless communication terminal.

Furthermore, in addition to the above-mentioned structure, in the wireless communication terminal of the present invention, the message includes at least identification information of the base station, identification information of the wireless communication terminal, and communication characteristic information on communication with the base station.

According to this structure, the characteristics of communication between the source and the destination can be grasped by referring to the message.

In addition, in addition to the above-mentioned structure, the wireless communication terminal of the present invention further includes: a stability evaluation part for based on the beacon signal received from the base station through each of the plurality of wireless communication interface parts, or based on the information on stability of communication between other wireless communication terminals and a base station to evaluate stability of communication between each of said plurality of wireless communication interface parts and a base station, wherein said other wireless communication terminal is notified of said information.

According to this configuration, it is possible for a wireless communication terminal to evaluate the stability of communication with the base station based on a beacon signal received from the base station or information on the stability of communication with the base station exchanged with other wireless communication terminals.

Furthermore, in addition to the above-mentioned structure, in the wireless communication terminal of the present invention, the stability evaluation section is arranged to: Sort base stations.

According to this structure, it is possible for a wireless communication terminal to rank the stability of communication with each base station.

In addition, in order to achieve the purpose of the present invention, the present invention provides a wireless communication terminal comprising:

a plurality of wireless communication interface components, each of the plurality of wireless communication interface components being connectable to one or more base stations,

Stability information storage means for storing information on the stability of communication with a base station to which each of said plurality of wireless communication interface means is connectable, and

Stability determination means for determining whether to start communication between said wireless communication interface means and a base station based on information on stability stored in said stability information storage means.

According to this structure, it is possible to perform effective handover without unnecessary handover.

In addition, in addition to the above-mentioned structure, the wireless communication terminal of the present invention further includes a stability evaluation part for based on a beacon signal received from a base station through each of the plurality of wireless communication interface parts, or based on information on stability of communication between a wireless communication terminal and a base station to evaluate stability of communication between each of said plurality of wireless communication interface parts and a base station, wherein said information is notified from said other wireless communication terminal .

According to this configuration, it is possible for a wireless communication terminal to evaluate the stability of communication with the base station based on a beacon signal received from the base station or information on the stability of communication with the base station exchanged with other wireless communication terminals.

Furthermore, in addition to the above-mentioned structure, in the wireless communication terminal of the present invention, the stability evaluation section is arranged to: Sort base stations.

According to this structure, it is possible for a wireless communication terminal to rank the stability of communication with each base station.

In addition, in order to achieve the purpose of the present invention, the present invention provides a wireless communication terminal comprising:

a plurality of wireless communication interface components, each of the plurality of wireless communication interface components being connectable to one or more base stations,

Stability information storage means for storing information on the stability of communication with a base station to which each of said plurality of wireless communication interface means is connectable, and

a message sending section for sending a message requesting improvement of stability of communication to a base station whose stability becomes lower than a predetermined threshold level by referring to information on stability stored in said stability information storage section.

According to this structure, it is possible to improve the stability of communication of the wireless communication terminal.

Furthermore, in addition to the above-mentioned structure, in the wireless communication terminal of the present invention, the message includes at least identification information of the base station, identification information of the wireless communication terminal, and communication characteristic information on communication with the base station.

According to this structure, the characteristics of communication between the source and the destination can be grasped by referring to the message.

In addition, in order to achieve the purpose of the present invention, the present invention provides a network-side communication device that cooperates with a wireless communication terminal, including:

a wireless communication interface component for communicating with the wireless communication terminal,

information receiving means for receiving a message requesting improvement of stability of communication with the wireless communication terminal from the wireless communication terminal via the wireless communication interface means, and

communication stability improving means for improving stability of communication with the wireless communication terminal which is the source of the message by controlling the operation of the wireless communication interface means.

According to this structure, it is possible to improve the stability of communication between the network-side communication device and the wireless communication terminal.

Furthermore, in addition to the above-mentioned structure, in the network-side communication device of the present invention, the communication stability improving means is arranged to increase transmission power, or adjust towards the Describe the directional characteristics of wireless communication terminals.

According to this structure, the network-side communication device can improve the stability of communication with the wireless communication terminal by increasing transmission power or adjusting directional characteristics.

The present invention including the above structure has the advantage of achieving fast interface switching for seamless handover and/or performing efficient handover instead of unnecessary handover. The present invention also has the advantage of improving the stability of communication (especially, link connection) of a wireless communication terminal.

Description of drawings

1 is a diagram showing a top view of a network in which a mobile node roams across overlapping areas covered by multiple networks in an embodiment of the invention;

FIG. 2 is a block diagram showing a structural example of a mobile node in an embodiment of the present invention;

FIG. 3 is a state diagram illustrating a fast interface switching operation in an embodiment of the present invention;

Figure 4 is a state diagram illustrating reliable interface switching operations in an embodiment of the present invention;

Figure 5 is a state diagram illustrating fast and reliable interface switching operations in an embodiment of the present invention;

6 is a diagram showing an example of information elements included in a Proximity Notification message transmitted from a mobile node in an embodiment of the present invention;

Figure 7 is a block diagram showing an example of the structure of a network node (potential point of attachment) in an embodiment of the present invention; and

FIG. 8 is a state diagram illustrating an example of an operation regarding a proximity notification message in an embodiment of the present invention.

Detailed ways

Description will be given below regarding embodiments of the present invention with reference to the drawings. 1 depicts a typical example of a mobile node 100 roaming in a neighborhood where there are multiple overlapping areas of network coverage, such as a cellular base station 105 and WLAN APs 110, 115, 120, 125, and 130. In the description, cellular base stations are referred to simply as base stations. Mobile node 100 may take route 135 whereby it passes the edge of the overlapping WLAN network coverage area while remaining within its cellular network coverage area. To enable fast and reliable handoffs, the system may include some key features.

For fast interface switching, the system of the invention should have some means for saving broadcast information even about interfaces that are not activated or involved in the current communication. Thus, as an example, the wireless LAN interface may passively listen for any broadcast beacons by neighboring access points or access routers. Store received beacon information.

Depending on the capabilities of the device, the stored beacon information can be placed in a list or constantly replaced by the most recently received information (latest information). Thus, nodes with strict power and/or information storage requirements may store only the most recently received beacon information, while those nodes with less stringent requirements may store a greater number of beacon information. Storing beacon information may be useful in cases where the baseband is in an area covered by two or more access points or routers.

For devices that store more than one beacon information, it may be useful to store beacons according to source identification. In this way, only the most recent beacon information from each source is stored, rather than all beacon information from a single source over a short beacon period.

For lower layer cues or events that support e.g. LINK_GOING_UP (a trigger from the media interface indicating that a new link will become available) or LINK_GOING_DOWN (a trigger from the media interface indicating that the current link will become unavailable) nodes, the previously described method can be further enhanced. Examples of such low layer media interface events may be those provided by the Media Independent Handover function defined in IEEE802.21. Listening done on all interfaces can be tied to receipt of a trigger alert when the current link is going down, or when a potential new link is detected, thus conserving the limited power of the mobile node.

When the currently used link is unavailable, or when the mobile node decides to switch links or interfaces due to certain policy decisions, the mobile node must select an alternative interface or link to utilize. This selection may be influenced by the availability of stored information as previously described, in addition to any other policy considerations. Upon successful selection of an interface, any stored information about the selected interface is immediately put to use, and, in this way, the mobile node's connectivity can be quickly re-established.

The functional structure required for such a system is shown in FIG. 2 . Mobile node 100 includes media interfaces 200 , 205 and 210 . Media interfaces 200, 205, and 210 are logical interfaces that can be viewed as physical interface cards that nodes use to communicate with external networks. For example, media interfaces 200, 205 and 210 include WLAN cards, GSM cards or even modems.

Media interfaces 200, 205, and 210 may also represent links to different attachment points. For example, a Bluetooth interface connected to two separate peers can be viewed as two corresponding media interfaces, one used by each peer. Media interfaces 200 , 205 and 210 may communicate and be configured by management entity 215 via respective message paths 250 , 255 and 260 .

The management entity 215 is a general controller, which manages various network functions of the nodes. Furthermore, the management entity 215 should include at least a stability control unit 220 and a configuration control unit 225 . It may also include other functions, such as those that determine and control handover from one point of attachment to another. Policy controller 230 provides input information from its policies to management entity 215 via message path 265 to aid in its decision making. Alternatively, the management entity 215 may query the policy controller 230 via the message path 280 for the relevant parameters.

The management entity 215 also has access to at least two logical databases (stability information database 235 and configuration information database 240). Management entity 215 may write or retrieve information from these databases via message paths 270 and 275, respectively.

The stability information database 235 maintains information pertaining to the stability of any nearby or currently encountered potential network attachment points. Examples of stored information include the type of access technology used for the connection, the identifier of the point of attachment, its detected signal strength and bit error rate (BER), or some other parameter describing the stability of the point of attachment. metrics.

The media interfaces 200, 205, and 210 may implement a detection function for detecting signal strength or bit error rate, and, based on a beacon signal received from a base station, may store detection results such as signal strength or bit error rate as indication A measure of stability. Base stations capable of connecting to media interfaces 200, 205, and 210 may send the above metrics to the mobile node to indicate the stability embedded in the beacon signal (e.g., information indicating the state of the point of attachment), and the mobile node may Stores the information in its stability information database 235 . Furthermore, if metrics are exchanged among mobile nodes, each mobile node can obtain metrics indicating stability for each point of attachment. The stability of each attachment point is ranked (categorized) by the mobile node 100 based on the metric used to indicate stability in the stability information database 235 . In this case, for example, the mobile node 100 may classify stability such that attachment points with better communication quality are ranked higher, or such that attachment points are ranked taking into account patterns or trends. The above pattern refers to the detected time trend of the metric used to indicate stability. Regarding the mode, for example, if the stability of an attachment point gradually increases over time, it is preferable that the attachment point is ranked higher. The above trends refer to the detection frequency of the metric used to indicate stability. With respect to trends, for example, an attachment point is preferably ranked higher if the frequency of detection of its metric increases in a given time period.

Configuration information database 240 maintains any configuration information obtained from all potential attachment points. Depending on the storage space relationship, this information may be an ordered list for each attachment point or just the most recently received information. Examples of each information could be beacon information from a WLAN access point, which could include information such as future beacon intervals, supported data rates, parameter settings and performance information, or information on layer 2 links Carried higher layer information such as a Router Advertisement message including prefix information and other service announcements. Preferably, by a medium access decision unit placed between the network access unit (including PHY (Physical Layer), MAC (Media Access Control), LLC (Logical Link Control), etc.) and higher layers (Layer 3 and above) The information storage function is used to realize the stability information database 235 and the configuration information database 240.

A stability control unit 220 residing in the management entity 215 controls the classification of the stability of its peers. It processes the received information and stores or retrieves them from the stability information database 235 . It can be configured to receive thresholds or ranges of parameters in order to classify potential points of attachment. It may also be responsible for selecting potential links or interfaces to present to the node for selecting the next handover target based on their stability metrics and any threshold parameters.

Configuration control unit 225 controls the storage and retrieval of any received configuration information from media interfaces 200 , 205 and 210 . It may also be responsible for delivering to the node the configuration information most recently received from the handover target once the selection of the handover target is complete.

The operation for fast interface switching is shown in the state diagram of FIG. 3 . In FIG. 3, the mobile node 100 starts in an idle state (step 300). As shown in step 305, according to its power strategy, the mobile terminal can actively collect and store information about nearby potential attachment points (step 310), or only start its listening and storing process at the time of immediate handover ( Step 320).

When it is determined (or indicated) to start the handover process, the handover process is promptly invoked (step 325). When the mobile node has selected an interface or link for handover to, information about the selected interface or link (previously stored information) is passed to the mobile node (step 330) in order to process the handover immediately without waiting for the next broadcast beacon. The mobile node recognizes the completion of any other required handover procedures (step 335), after which normal operating procedures will apply, and then return to the initial state (idle state of step 300). If no information is stored about the selected interface or link (for example, in the case where it is determined that the required information cannot be collected before starting the handover process), normal procedures will be returned and the information collected from the next broadcast beacon will be The information is passed to the mobile node.

As the mobile node 100 roams along the edge of overlapping network coverage, the availability of the network may be temporary in nature from the perspective of the mobile node 100 . In order to prevent the selection of temporary interface links that would cause unwanted handovers, a system for influencing interface selection based on the stability of the network is desired. The system is a reliable interface switching system for classifying available interfaces or links based on a history of events.

During the collection of the above information, the mobile node 100 should also keep records of the received information on various interfaces. This record provides a history of the various possible links for the interface. This differs from the previously described information storage means in that not all information obtained from any received broadcast needs to be stored. The log keeps track of various sources of broadcast information and attempts to classify links into stable and transient categories.

The records may be updated by processing received broadcasts, alerts, events, triggers, or any other information otherwise obtained about potential points of attachment in the vicinity of the mobile node 100 . For example, if the periodicity of received beacons is constant, it may be assumed that the access point from which the beacon was sent provides a relatively stable connection compared to another access point's beacon that is only received intermittently.

Potential attachment points with transient or unstable records may not be reported for consideration (considered as candidates for handover targets) when a node is selecting an alternative point of attachment to the network. The specific threshold used to decide whether to report a potential link is medium-specific and may or may not share a similar value used to classify records as stable. An example could be using the average signal strength of received beacons to determine whether to report the link to a node. Another example of a threshold may be the percentage of packets received in error.

Operations for reliable interface switching are shown in the state diagram of FIG. 4 . The mobile node 100 starts in an idle state (step 400). As shown in step 405, according to its power policy, the mobile node 100 can actively collect and store information about nearby potential attachment points, and also classify links according to stability (step 410), or only Its listening and storing process, and classifying links according to stability (step 420) begin only when they are handed over (step 415).

When it is determined (or indicated) to start the handover process, the handover process is promptly invoked (step 425). When the mobile node selects an interface or link to handover to, information about the various possible attachment points on all interfaces is consulted, and only those passing an arbitrary threshold are passed to the mobile node 100 to be considered for handover Candidates for the target (step 430). The mobile node 100 selects one for handover from the received candidates. The mobile node then recognizes the completion of any other required handover procedures (step 435), following which normal operating procedures will apply and then return to the initial state (idle state of step 400). If the information about the selected interface or link has not been stored (for example, in the case where it is determined that the required information cannot be collected before starting the handover process), the normal process will be returned, and then the The information is transmitted to the mobile node.

Operations for reliable interface switching are shown in the state diagram of FIG. 5 . The mobile node 100 starts in idle state (step 500). As shown in step 505, according to its power policy, the mobile node 100 can actively collect and store information about nearby potential attachment points, and also classify links according to stability (step 510), or only in immediate handover ( Step 515) begins its listening and storing process, and classifies links according to stability (step 520). Note that the processing of information about nearby potential attachment points and the storage of information received via broadcasts from them are separate processes and may be governed by different policies. Thus, the mobile node 100 may always process information and classify potential points of attachment into different stability classes, while only activating the storage of information when handover is immediate.

When it is determined (or indicated) to start the handover process, the handover process is promptly invoked (step 525). When the mobile node selects an interface or link to handover to, it consults information about the various possible attachment points on all interfaces, and only passes those that pass an arbitrary threshold to the mobile node 100 (step 535) for consideration Candidates for handover targets (step 530). Subsequently, the mobile node 100 selects one of the received candidates for handover. The mobile node recognizes the completion of any other required handover procedures (step 540), after which normal operating procedures will apply, and then returns to the initial state (idle state of step 500). If no information is stored about the selected interface or link (for example, in the case where it is determined that the required information cannot be collected before starting the handover process), the normal process will be returned, and then the next broadcast beacon will collect The information is transmitted to the mobile node.

According to the prior art, when the mobile node 100 roams along the path 135, since it touches the network coverage of the WLAN APs 110, 115, 120, 125 and 130, the mobile node 100 will continuously handover from the base station 105 to the WLAN APs 110, 115, 120, 125, and 130. This wastes network resources as the mobile node reconfigures itself, and also causes a less-than-ideal user experience of constant interruption.

On the other hand, following the steps of the present invention, when the mobile node 100 roams, it first starts connecting via the base station 105 . The interface detects the presence of WLAN APs 110 and 115 near location A in FIG. 1 . However, since the signal strength of both these WLANAPs 110 and 115 is low due to the mobile node 100 being at the edge of their coverage, the stability control unit 200 records their presence but does not present them to the mobile node 100 as a handover candidate.

The above-mentioned events are repeated when the mobile node 100 roams from the WLAN APs 110, 115, 120, and 125. The configuration control unit 225 will store any broadcast information (such as beacons) received from these WLAN APs 110, 115, 120, and 125, but the stability control unit 220 will not pass them on to higher layers in the mobile node 100 for Considered a candidate for handover.

When the mobile node 100 roams into the coverage of the WLAN AP 130, the stability control unit 220 recognizes the stability of the received signal, and delivers information that the WLAN AP 130 is considered a handover candidate to higher layers in the mobile node 100 . Assuming that the policy of the mobile node 100 dictates the handover, the configuration control unit 225 passes any broadcast information such as previously received beacons and (if any) received higher layer configuration information to the higher layers. The mobile node 100 will then configure itself to utilize the WLAN AP 130 without waiting for the next beacon or information broadcast from the WLAN AP 130. This allows handovers resulting in higher network efficiency and better network experience.

When the mobile node 100 resides in the network coverage area of that potential point of attachment, the mobile node 100 may send a remote trigger requesting to improve the stability (reliability) of the connection to a particular potential point of attachment. By receiving this remote trigger, the potential point of attachment improves the stability of the connection to the mobile node 100 that is the source of the remote trigger by, for example, increasing electrical power or adjusting the directional characteristics of the wireless signal. The mobile node 100 recognizes an improvement with respect to the stability of the received signal and, as a result, the mobile node 100 will likely attach to this potential point of attachment.

The potential point of attachment does not always have to improve the stability of the connection to the mobile node 100 that is the source of the remote trigger despite receiving the remote trigger. Potential points of attachment can improve stability to all mobile nodes that are sources of remote triggers. A potential point of attachment may improve the stability of a connection to a part of a mobile node that is the source of a remote trigger (e.g., the mobile node meets some other requirement or is chosen randomly), but ignores remote triggers from other mobile nodes .

When the mobile node 100 is roaming along the route 135 shown in FIG. Next Proximity Notification Message) is sent to the selected potential attachment point for further action.

In FIG. 6, an example of information elements included in a proximity notification message transmitted from a mobile node in an embodiment of the present invention is illustrated. Typically, the proximity notification message illustrated in FIG. 6 is sent by the mobile node 100 to potential attachment points. By receiving the proximity notification message, the potential point of attachment can perform operations regarding the mobile node 100 .

For example, by receiving the proximity notification message, the potential point of attachment may perform operations to make the current communication link with the mobile node 100 more stable, may perform operations to enhance the communication link in order to establish a communication link with the mobile node 100 (i.e., in order to direct the mobile node 100 to connect), or if a communication link is established with the mobile node 100, any required active operations may be performed.

To be more precise, the potential attachment point may increase the strength of the transmitted information (electrical power of the signal transmission) when receiving the proximity notification message. Furthermore, the potential point of attachment may direct the interface towards the mobile node 100 in order to adjust the directional characteristics of the wireless signal when an indication is received from the mobile node 100 that the received signal strength is weak.

It should be noted that the proximity notification message may be created and sent alone or piggybacked when other data, control or management plane messages are exchanged between the mobile node 100 and its potential points of attachment.

The proximity notification (Proximity Notification) message includes 4 fields to insert information elements (destination ID field 601, source ID field 602, communication parameter field 603 and additional information field 604), as shown in FIG. 6 .

Destination ID field 601 includes an identifier describing the destination of the proximity notification message. Examples of this identifier may be the APID of an IEEE802 access point or the MAC ID of an IEEE802 node.

Source ID field 602 includes an identifier of the node that sent the proximity notification message, an example of which may be the MAC ID of the interface on the mobile node 100 that sent the proximity notification message.

The communication parameter field 603 includes structured information describing the state of communication, such as physical communication characteristics and logical communication characteristics between the destination and source nodes. Mobile node 100 may send information such as the detected strength or quality of signals received from potential attachment points. In another implementation, the communication parameter field 603 may also include communication parameters of the mobile node 100, such as current transmission power and maximum settings.

Additional information field 604 is an optional field for a potential point of attachment, which may include information, such as information from the mobile node 100 related to authentication, location or mobility.

In order to send the above-mentioned proximity notification message to a potential point of attachment, the functionality of the mobile node 100 illustrated in FIG. 2 must be enhanced. When the management entity 215 receives a notification from the stability control unit 220 that a potential attachment point does not meet the stability criteria, according to the policy obtained via the policy controller 230, the management entity 215 can , sending the aforementioned proximity notification message to the potential attachment point.

In order to process the above mentioned proximity notification message, the potential point of attachment (network node 700) implements the functionality described in FIG. 7 . Fig. 7 is a block diagram showing a structural example of a network node (potential point of attachment) in the embodiment of the present invention.

Network node 700 includes one or more media interfaces 710 . When a proximity notification message is received from the mobile node 100 , the associated media interface 710 shall proceed to: send the proximity notification message to the management entity 705 via the message path 720 .

The management entity 705 retrieves the information included in the proximity notification message and, via the message path 730, passes the information to the policy controller 715 to negotiate with the policy controller 715 the appropriate action to be performed. The management entity 705 receives policy services provided from the policy controller 715 . When an action to be performed is determined based on the policy service, the management entity 705 may send a command to the relevant media interface 710 via the command path 725 to take appropriate steps accordingly, such as for improving the stability of the communication with the mobile node 100 It is a proactive process to make the mobile node 100 quickly connect (communication start). In a specific example, the management entity 705 may indicate the medium interface 710 determined by the proximity notification message in order to increase the stability of the received signal on the mobile node 100 side.

The management entity 705 is located in the network node 700 in Fig. 7, but the management entity 705 may be located outside the network node 700 (physically at another location). For example, management entity 705 may be located in an access router that manages multiple access points. Similarly, policy controller 715 may be located external to network node 700 .

When the management entity 705 is located outside the network node 700, the message path in FIG. 7 can be replaced by TCP/IP (Transmission Control Protocol/Internet Protocol) by using a network path for communication to the management entity 705 residing outside the network node 730 to transmit the policy service.

FIG. 8 is a state diagram showing an example of an operation regarding a proximity notification message in an embodiment of the present invention. In the state diagram of FIG. 8 , a summary of the additional behavior of the mobile node 100 having the function of sending proximity notification messages is depicted.

In FIG. 8, the mobile node 100 always listens, collects information on all interfaces, and classifies links (links are classified based on stability) (step 800). In addition, the mobile node 100 monitors whether the link is stable (step 810). When the link is considered stable, as shown by the loop of transitions 805 and 815, the mobile node 100 performs no specific action and continues to monitor the link status.

However, if the link is found to be insufficiently stable (e.g., a link classified as stable becomes below a certain level (a certain threshold)), the management entity 214 of the mobile node 100 may take a decision to provide the selected potential attached Connect to send a proximity notification message (step 820). A proximity notification message is sent from the mobile node 100 to the potential point of attachment, then via transition 825 it goes back to the link monitoring state again.

In the description, while the invention has been shown and described in what is considered to be the most practical and preferred embodiment, it will be understood by those skilled in the art that various design details and parameter modifications may be made, such as those managed in FIG. Changes in the design of entity 215, management entity 715 in FIG. 7, or other structural components may be made without departing from the scope and bounds of the present invention.

Each functional block to be used in the above-mentioned embodiments of the present invention is realized as an LSI (Large Scale Integration) which is an integrated circuit. The functional blocks may be respectively handled as 1-chips, and part or all of the functional blocks may be handled as 1-chips so as to be included in 1-chips. The above LSI may be called IC (Integrated Circuit), System LSI, or Super LSI according to the level of integration.

In addition, methods that are handled as integrated circuits are not only for manufacturing LSIs but also for creating dedicated circuits or general-purpose processors. After the production of LSI, FPGA (Field Programmable Gate Array) is programmable or the reprocessor is reset, the connection or configuration of the circuit unit can be realized.

Furthermore, if another new integration technology instead of LSI appears due to development of semiconductor technology or creation of another technology, functional blocks can of course be integrated by using the new technology. For example, biotechnology can be the new technology.

Industrial Applicability

The present invention has the advantages of obtaining fast interface switching for seamless handover and/or performing efficient handover instead of unnecessary handover, and improving the communication stability (especially, link connection) of wireless communication terminals advantage. The invention can be applied to the communication field of packet switching data communication network.

Claims (17)

1. wireless communication terminal comprises:

A plurality of wireless communication interface parts, each of a plurality of wireless communication interface parts can be connected to one or more base stations,

The beacon message memory unit is used for storing the information that is included in beacon signal, and wherein, periodically send from described base station and receive described beacon signal by each of described a plurality of wireless communication interface parts,

The beacon message searching part is used for being included in from the retrieval of described beacon message memory unit the information of beacon signal, according to predetermined trigger, and by receiving described beacon signal with the corresponding wireless communication interface parts of described predetermined trigger, and

Communication control unit is used for using the information that is included in beacon signal to control beginning and communicates by letter on described wireless communication interface parts, wherein retrieves described beacon signal by described beacon message searching part.

2. wireless communication terminal as claimed in claim 1, comprise communication switching controls parts, be used for when on any one of described a plurality of wireless communication interface parts, beginning to communicate by letter or when on any one of described a plurality of wireless communication interface parts, switching attachment point, predetermined trigger is provided to described beacon message searching part, wherein said predetermined trigger with begin to communicate by letter or to switch the wireless communication interface parts of the base station that will connect corresponding.

3. wireless communication terminal as claimed in claim 1, comprise the information stores control assembly, be used for based on the beginning of communicating by letter on the described wireless communication interface regularly, on described wireless communication interface, be connected to the switching timing of base station and about any one of the strategy of electrical power, control monitoring about the beacon signal of described wireless communication interface, maybe will be included in information stores in the beacon signal in the beacon message memory unit.

4. wireless communication terminal as claimed in claim 1 comprises:

Stability information stores parts, be used to store about with the information of the stability of base station communication, each of wherein said a plurality of wireless communication interface parts can be connected to described base station, and

Stability is determined parts, is used for based on the information about stability that is stored in described stable information stores parts, and determining whether can be with described base station selected candidate for being used to communicate by letter.

5. wireless communication terminal as claimed in claim 4, comprise the stability assessment parts, be used for based on each beacon signal that receives from the base station by described a plurality of wireless communication interface parts or based on information about the stability of between other wireless communication terminals and base station, communicating by letter, be evaluated at the stability of communicating by letter between each and the base station of described a plurality of wireless communication interface parts, wherein, notify described information from described other wireless communication terminals.

6. wireless communication terminal as claimed in claim 5 wherein, is arranged to described stability assessment parts: based on the information relevant with the stability of communication or the frequency of detected beacon signals the time become pattern, come to be sorted in the base station.

7. wireless communication terminal as claimed in claim 1 comprises:

Stability information stores parts, be used to store about with the information of the stability of base station communication, each of wherein said a plurality of wireless communication interface parts can be connected to described base station, and

The message transmit block is used for becoming the base station that is lower than predetermined threshold level to its stability and sending the message that request improves the stability of communication by with reference to the information about stability that is stored in described stable information stores parts.

8. wireless communication terminal as claimed in claim 7, wherein, described message comprise at least the base station identifying information, wireless communication terminal identifying information and about with the communication feature information of communicating by letter of base station.

9. wireless communication terminal as claimed in claim 7, comprise the stability assessment parts, be used for based on each beacon signal that receives from the base station by described a plurality of wireless communication interface parts or based on information about the stability of between other wireless communication terminals and base station, communicating by letter, be evaluated at the stability of communicating by letter between each and the base station of described a plurality of wireless communication interface parts, wherein, notify described information from described other wireless communication terminals.

10. wireless communication terminal as claimed in claim 9 wherein, is arranged to described stability assessment parts: based on the information relevant with the stability of communication or the frequency of detected beacon signals the time become pattern, come to be sorted in the base station.

11. a wireless communication terminal comprises:

A plurality of wireless communication interface parts, each of a plurality of wireless communication interface parts can be connected to one or more base stations,

Stability information stores parts, be used to store about with the information of the stability of base station communication, each of wherein said a plurality of wireless communication interface parts can be connected to described base station, and

Stability is determined parts, is used for based on the information about stability that is stored in described stable information stores parts, determines whether to begin between described wireless communication interface parts and base station communication.

12. wireless communication terminal as claimed in claim 11, comprise the stability assessment parts, be used for based on each beacon signal that receives from the base station by described a plurality of wireless communication interface parts or based on information about the stability of between other wireless communication terminals and base station, communicating by letter, be evaluated at the stability of communicating by letter between each and the base station of described a plurality of wireless communication interface parts, wherein, notify described information from described other wireless communication terminals.

13. wireless communication terminal as claimed in claim 12 wherein, is arranged to described stability assessment parts: based on the information relevant with the stability of communication or the frequency of detected beacon signals the time become pattern, come to be sorted in the base station.

14. a wireless communication terminal comprises:

A plurality of wireless communication interface parts, each of a plurality of wireless communication interface parts can be connected to one or more base stations,

Stability information stores parts, be used to store about with the information of the stability of base station communication, each of wherein said a plurality of wireless communication interface parts can be connected to described base station, and

The message transmit block is used for becoming the base station that is lower than predetermined threshold level to its stability and sending the message that request improves the stability of communication by with reference to the information about stability that is stored in described stable information stores parts.

15. wireless communication terminal as claimed in claim 14, wherein, described message comprise at least the base station identifying information, wireless communication terminal identifying information with about with the communication feature information of communicating by letter of base station.

16. a network side communication apparatus that is applicable to wireless communication terminal comprises:

The wireless communication interface parts are used for communicating by letter with described wireless communication terminal,

Information receiving parts is used for via the wireless communication interface parts, from the message of wireless communication terminal reception request improvement with the stability of communicating by letter of wireless communication terminal, and

Communication stability improves parts, is used for operation by control wireless communication interface parts and improves the stability of communicating by letter with described wireless communication terminal, and wherein said wireless communication terminal is the source of described message.

17. network side communication apparatus as claimed in claim 16, wherein, described communication stability is improved parts to be arranged to: as the controlled operation of described wireless communication interface parts, increase transmitted power or the adjusting directional characteristic towards described wireless communication terminal.

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