JP4834506B2 - Connection terminal number balancing device and connection terminal number balancing method - Google Patents

Description

  The present invention relates to a wireless communication system provided with a plurality of wireless LAN access points (hereinafter referred to as wireless APs), and more particularly to a technique for reducing the deviation between the wireless APs in the number of terminals connected to the wireless AP. is there.

  FIG. 1 shows a configuration example of a conventional wireless communication system. As shown in FIG. 1, the wireless communication system includes a plurality of wireless LAN access points and a wireless LAN switch that manages wireless APs. Under the wireless AP, there are terminals such as a wireless VoIP terminal and a PC, which are connected to the wireless AP through a wireless link (hereinafter simply referred to as “connect”). In addition, a plurality of wireless APs are arranged together for each base, and each constitutes an adjacent wireless AP group. Within such a group of adjacent wireless APs, two adjacent wireless APs are arranged so that their radio wave reachable ranges overlap each other to some extent.

  In general, in an environment where a plurality of wireless APs exist adjacent to each other, there are many cases where there are adjacent wireless APs to which a terminal can be connected, in addition to a wireless AP to which a certain terminal is connected. However, since the wireless AP to which the terminal is connected is determined by the location of the terminal, when a large number of terminals exist only in the vicinity of the specific wireless AP, a large number of terminals are connected to the wireless AP. That is, even though other adjacent wireless APs can be used, there are few terminals connected to the wireless AP, and an imbalance of the number of connected terminals occurs between the wireless APs.

  When many terminals are connected to one wireless AP, there is a possibility that the communication resources of the wireless AP are consumed by many terminals. In such a case, the amount of resources allocated per terminal is reduced, and the communication quality of the terminal is degraded.

  To prevent such problems from occurring in an environment where multiple wireless APs exist adjacent to each other, eliminate the imbalance in the number of connected terminals between wireless APs and equalize the number of connected terminals between wireless APs. It is demanded to become.

  As a conventional technique for eliminating the imbalance of the number of connected terminals between adjacent wireless APs, there is a technique described in Patent Document 1.

In the technique described in Patent Document 1, the average bandwidth usage of each terminal connected to the wireless AP is monitored, and the total of the average bandwidth usage of all the connected terminals is set to one preset value. When the threshold is exceeded, at least one terminal is forced to roam to another wireless AP.
JP 2005-536913 A

  In the method of selecting a terminal to be disconnected based on only one threshold value for each wireless AP connected terminal in each wireless AP, the terminal is frequently disconnected, which may cause problems in operability from the user's viewpoint. There is sex. In particular, in the imbalance cancellation method based on the used bandwidth monitoring, a specific terminal having a large used bandwidth may be frequently disconnected, and may be routed between adjacent wireless APs.

  The present invention has been made in view of the above points, and provides a new technique for preventing the occurrence of the problems of the prior art and solving the imbalance in the number of connected terminals between adjacent wireless APs. Objective.

  The above-described problem is a connected terminal number balancing device for balancing the number of terminals connected to each wireless AP between a plurality of adjacent wireless APs, and each wireless AP connects to the wireless AP. Terminal information acquisition means for acquiring the terminal identification information and the radio wave intensity of the terminal and storing the information in the storage means, and for a certain wireless AP, the number of terminals connected to the wireless AP is determined in advance. The first reference value comparing means for comparing the first reference value and the first reference value comparing means determine that the number of terminals connected to the wireless AP exceeds the first reference value. In this case, an average value of the number of connected terminals between the wireless AP and the wireless AP adjacent to the wireless AP or a value obtained by converting the average value into an integer is calculated, and the terminal connected to the wireless AP The value obtained by subtracting the predetermined second reference value from the value obtained by subtracting the value from the number of is a positive value. The number of terminals to be a candidate for disconnecting from the wireless AP based on the value, and a reference to the number of disconnected terminals, the storage means, and all of the terminals connected to the wireless AP or Terminal extraction means for extracting a maximum number of terminals corresponding to the number of terminals in ascending order of radio field intensity, and a terminal for disconnecting all or part of the terminals extracted by the terminal extraction means from the wireless AP This is solved by a connection terminal number balancing device comprising a disconnecting means.

  The connected terminal number balancing device may not disconnect a terminal having a radio field intensity greater than a predetermined radio field intensity from the wireless AP. Further, the connected terminal number balancing device may not disconnect a terminal in communication with other terminals from the wireless AP. Further, the connected terminal number balancing device is a terminal that is disconnected from another wireless AP before being connected to the wireless AP among the terminals connected to the wireless AP, It is good also as not cut | disconnecting the terminal in which predetermined time has not passed since it cut | disconnected from.

  In the present invention, when the number of connected terminals of the target wireless AP (referred to as target wireless AP) is larger than the first reference value, the average value of the number of connected terminals between adjacent wireless APs and the connected terminal of the target wireless AP The terminal is disconnected when the difference from the number is larger than the second reference value.

  When the terminal is disconnected when the number of connected terminals of the target wireless AP is larger than the first reference value, that is, when the terminal is disconnected with only one threshold relating to only the target wireless AP, If the number of connected terminals is large even in the AP, there is a problem that disconnection occurs again in the adjacent wireless AP, and disconnection occurs frequently.

  On the other hand, in the present invention, since the determination using the average value of the number of connected terminals between adjacent wireless APs is further performed, it is possible to perform the determination taking into account the number of connected terminals in the adjacent wireless AP. is there. That is, if the number of connected terminals in the adjacent wireless AP is large, the difference between the average value and the number of connected terminals of the target wireless AP is small. Therefore, the terminal is not disconnected and the above problem can be avoided. On the other hand, if the number of connected terminals of the target wireless AP is large and the number of connected terminals in the adjacent wireless AP is small, the difference between the average value and the number of connected terminals of the target wireless AP is large, and the terminal is disconnected. Since the number of connected terminals in the wireless AP is small, the disconnected terminal can be stably connected to the adjacent wireless AP, and can be balanced and realize a stable connection.

  Furthermore, it is possible to adjust the degree of balancing by appropriately setting the second reference value. For example, if the second reference value is decreased, the terminal is disconnected more frequently than when the second reference value is large, but the degree of balancing is improved. On the other hand, if the second reference value is increased, the degree of balancing becomes smaller than when the second reference value is small, but the terminal will not be disconnected even if there is a small amount of imbalance. And the terminal connection state can be made more stable than when the second reference value is small.

  In the present invention, since a terminal with weak radio field strength is selected as a terminal to be disconnected, there is a high possibility that the disconnected terminal can connect to a wireless AP with better connection conditions.

  In addition, it is assumed that a terminal in communication state is not disconnected, and a terminal connected to another wireless AP after being disconnected from one wireless AP is not disconnected again until a predetermined time elapses after being disconnected. By doing so, the connection state of the terminal can be further stabilized.

  Embodiments of the present invention will be described below with reference to the drawings. First, the basic configuration will be described, and then a specific example will be described.

<Basic configuration>
FIG. 2 shows an example of a wireless communication system in the embodiment of the present invention. The system shown in FIG. 2 is obtained by adding an access controller 30 (also referred to as a connected terminal number balancing device) to the wireless communication system shown in FIG. The access controller 30 can be provided in place of the wireless LAN switch in FIG. 1 or in the wireless LAN switch.

  FIG. 3 shows a schematic functional configuration diagram of the access controller. As shown in FIG. 3, the access controller 30 includes at least a terminal information acquisition unit 36, a database 35 that stores setting information that is predetermined information and the acquired information, a disconnected terminal determination unit 37, and a terminal control unit 38. Have.

  The terminal information acquisition unit 36 acquires information on terminals connected to the wireless AP, information on their radio field strength, and communication status of the terminals. The radio wave intensity is the intensity of the radio wave received by the wireless AP from the terminal. The disconnected terminal determination unit 37 analyzes the equilibrium state between adjacent wireless APs using the information stored in the database 35, determines the number of terminals that are candidates for disconnecting from the wireless AP based on the analysis result, and implements it. Determine the terminal to disconnect. The terminal control unit 38 transmits a wireless link disconnection request to the wireless AP connected to the terminal so as to disconnect the terminal determined to be disconnected.

  Next, an outline of the operation of the system will be described with reference to FIG. FIG. 4A shows a state in which three terminals of terminal D, terminal C, and terminal A are connected to the wireless AP 10 and only terminal B is connected to the wireless AP 20.

  The access controller 30 acquires the identification information of the connected terminal and the radio wave intensity of the connected terminal from each wireless AP at regular intervals, and holds them in the database 35 (step A). In the example of FIG. 4A, it is assumed that the radio wave intensity is terminal C> terminal B> terminal A.

  The access controller 30 checks the equilibrium state based on the number of terminals that are wirelessly connected to each wireless AP and a reference value that is set in advance, and determines whether the terminal is disconnected (step B). In the example of FIG. 4A, the access controller 30 determines to disconnect one terminal among the terminals connected to the wireless AP 10. Then, the access controller 30 determines to disconnect the terminal A having the weakest radio wave intensity from the wireless AP 10, transmits a wireless link disconnection request for disconnecting the terminal A to the wireless AP 10, and receives this request. The wireless AP 10 sends a wireless link disconnection instruction to the terminal A (step C).

  The terminal A that has been disconnected from the wireless link connects to the wireless AP 20 that is another connectable wireless AP (step D). As a result, the number of connected terminals between adjacent wireless APs is balanced (FIG. 4B).

  Hereinafter, the process performed by the access controller 30 to determine the terminal to be disconnected and disconnect the terminal will be described with reference to the flowchart of FIG. Note that the processing shown in the flowchart of FIG. 5 is executed at a predetermined cycle.

  In the database 35 of the access controller 30, for each of the first reference value, the second reference value, and each wireless AP to be managed for determining the unbalanced state, the wireless AP is adjacent to which wireless AP. Is set. In addition, in the database 35 of the access controller 30, the identification information of the connection terminal and the information on the radio wave intensity for each connection terminal acquired at a constant cycle are recorded for each wireless AP.

  In FIG. 5, the access controller 30 pays attention to the first wireless AP in the database 35 (for example, pays attention to the wireless AP of the first wireless AP number. Hereinafter, the focused wireless AP is referred to as the target wireless AP), and the target It is determined whether or not the number of wireless AP connected terminals exceeds the first reference value (steps 1 and 2). If not, the process moves to the next wireless AP (steps 21 and 22). If there is no next wireless AP, the process is terminated (step 100).

  If it is determined in step 2 that the number of connected terminals of the target wireless AP exceeds the first reference value, the average number of connected terminals between the target wireless AP and a wireless AP adjacent to the target wireless AP A value is calculated (step 3). For example, when the number of connected terminals of the target wireless AP is 11, and the wireless APs adjacent to the target wireless AP are wireless AP-1 and wireless AP-2, and the number of connected terminals is 2 and 2, respectively. The average value of the number of connected terminals is 15/3 = 5.

  Next, it is determined whether the difference obtained by subtracting this average value from the number of connected terminals of the target wireless AP is larger than the second reference value (step 4). If the average value is not an integer, the number after the decimal point may be rounded down or rounded to an integer, and the difference obtained by subtracting the integer value from the number of connected terminals of the target wireless AP may be compared with the second reference value. . In the process of step 4, it is determined whether or not the value obtained by subtracting the second reference value from the value obtained by subtracting the average value from the number of terminals connected to the target wireless AP is a positive value. Is equivalent to that. When the difference is not larger than the second reference value (No in step 4), the process is transferred to the next wireless AP.

  When the difference is larger than the second reference value (Yes in step 4), a value obtained by subtracting the second reference value from the difference is obtained, and that value is set as the number of terminals that are candidates for disconnection from the target wireless AP (step). 5). If the average value is not converted to an integer in the determination in step 4, and if the value obtained by subtracting the second reference value from the difference is not an integer, the value obtained by subtracting the second reference value from the difference is rounded down or rounded off. To an integer. When this value becomes 0, the processing is transferred to the next wireless AP. FIG. 6 shows an example of a mathematical formula for obtaining the number of disconnection candidate terminals of the target wireless AP. In FIG. 6, the symbol [] indicates that the decimal part is rounded down. Wireless AP2 to wireless APn are wireless APs adjacent to the wireless AP1.

  For example, in the above example, if the number of connected terminals of the target wireless AP-average value is 11-5 = 6 and the second reference value is 3, 6 is greater than 3 and 6-3 is 3. Therefore, the number of terminals that are candidates for disconnecting from the target wireless AP is three.

  Then, the access controller 30 identifies the terminals in communication state from the terminals connected to the target wireless AP, excludes them from the terminals to be disconnected, and connects before connecting to the target wireless AP. Terminals that have been disconnected from the wireless AP that has been disconnected in order to balance the number of terminals and for which a predetermined time has not passed since the disconnection are excluded from the terminals to be disconnected (step 6).

  Then, the access controller 30 lists the terminals whose radio field intensity is smaller than a certain radio field intensity from the terminals connected to the target wireless AP excluding the terminal excluded in step 6 from the database 35 in the order of weak radio field intensity, A maximum of several terminals calculated in step 5 are extracted from the weaker radio wave intensity (step 7). If there is no terminal whose radio field intensity is lower than a certain radio field intensity, the process moves to the next wireless AP.

  First, the process of step 7 is performed, and from the terminals extracted in step 7, terminals in communication state and terminals for which a predetermined time has not elapsed since the previous disconnection are excluded from the terminals to be disconnected. It is good as well.

  Then, the access controller 30 transmits a wireless link disconnection request to the target wireless AP so as to disconnect the terminal that remains as a result of the process of step 7, and disconnects (step 8). Thereafter, the processing is transferred to the next wireless AP. If there is no next wireless AP (No in step 21), the process is terminated.

<Specific example>
Next, a specific example will be described. This specific example is an example in which the present invention is applied to a wireless IP telephone system. In the wireless IP telephone system, as shown in FIG. 7, a SIP server is connected to a network, and call connection between terminals is performed by call control by the SIP server. In the wireless IP telephone system described in this specific example, since the access controller can grasp the call state of each terminal of each wireless AP, it identifies whether the terminal is in a communication state and is a target for disconnection. The terminal can be determined.

  First, the basic operation of this wireless IP telephone system will be described with reference to the sequence diagrams of FIGS. Each sequence diagram appropriately shows the structure of data held in each device. In addition, although the registrar and the SIP server are shown in the sequence diagram, they may be separate devices, or the registrar may be included in the SIP server. This registrar has functions similar to those of a general SIP-based registrar. In each sequence, MSID indicates the MAC address of the terminal, APID indicates the ID of the wireless AP, and URI indicates SIP-URI.

  First, a sequence for registering the VoIP terminal 1 (hereinafter referred to as terminal 1) in the access controller will be described with reference to FIG. The registration process shown in FIG. 8 is automatically performed when the terminal 1 is turned on, for example. Further, at the time shown in FIG. 8, the access controller is registered in the SIP server, and message transmission / reception based on SIP is possible between the access controller and the SIP server.

  In step 1 of FIG. 8, wireless link connection processing and authentication processing in the wireless LAN are performed between the terminal 1 and the wireless AP. Here, the wireless AP acquires and registers the MAC address (MSID) of the terminal 1 (step 2). The wireless AP transmits a terminal registration request including the wireless AP ID (AP01) and the MAC address (MS01) of the terminal 1 to the access controller (step 3). The access controller registers the wireless AP ID (AP01) and the MAC address (MS01) of the terminal 1 received from the wireless AP by storing them in the storage device (step 4). Then, the access controller returns a terminal registration response to the wireless AP (step 5).

  In step 6, the terminal 1 transmits a SIP register message to the registrar. The message to be transmitted includes MS01 and the URI (URI1) of terminal 1. The registrar performs normal register processing and transmits a URI registration request including MS01 and URI1 to the access controller (step 7). The access controller validates the URI by storing URI1 in association with AP01 and MS01 (step 8), and sends a URI registration response to the registrar (step 9). Then, the registrar returns a response to the register message in step 6 to the terminal 1 (step 10).

  In the example described here, the MAC address and URI of the terminal are stored in the access controller in the sequence, but these data are stored in advance in the access controller and only state changes are recorded. It is good. In this case, for example, AP01 is recorded in association with MS01 registered in advance in step 4, and information that URI1 is valid is recorded in association with AP01, MS01, and URI1 in step 8.

  Next, processing for deleting the registered terminal 1 from the access controller will be described with reference to FIG. The process shown in FIG. 9 is executed, for example, when the terminal 1 is turned off.

  In step 1 of FIG. 9, the terminal 1 transmits a register message including a registration deletion command to the registrar. The registrar sends a URI deletion request to the access controller (step 2), and the access controller that receives this request invalidates the URI by deleting URI1 from the database (step 3). The access controller returns a URI deletion response (step 4), and the registrar returns a response to the terminal 1 (step 5).

  In Step 6, when the terminal 1 leaves the wireless AP (disconnects the wireless link with the wireless AP), the wireless LAN process is performed, and the wireless AP receives the MSID and deletes the MSID (Step 7). A terminal deletion request is transmitted to the access controller (step 8), and the access controller that has received this deletes AP01 and MS01 from the database (step 9), and returns a terminal deletion response to the wireless AP (step 10).

  Next, with reference to FIG. 10 to FIG. 12, an operation when an incoming request is made from the terminal 2 to the terminal 1 under the wireless AP that is not congested will be described.

  The source terminal 2 transmits a call connection request (INVITE) to the SIP server (step 1 in FIG. 10). The SIP server that has received the INVITE transmits a QoS reservation request including the source terminal URI (URI2), the destination terminal URI (URI1), and the necessary bandwidth to the access controller (step 2). The access controller sets the call state for the terminal 1 to “QoS reservation in progress”, searches the database based on the destination URI 1, and extracts the wireless AP having the terminal 1 under control (step 3). Then, a QoS reservation request including MS01 and necessary bandwidth is transmitted to the wireless AP (step 4). The wireless AP reserves a bandwidth for the terminal 1 (step 5), returns a QoS reservation response to the access controller (step 6), and the access controller returns a QoS reservation response to the SIP server (step 7). Thereafter, a sequence based on normal SIP is executed (steps 8 to 12).

  In this example, the wireless AP manages the bandwidth and reserves / reserves the bandwidth, but the access controller has a function to manage the bandwidth of the wireless AP and control resources such as bandwidth reservation / reservation. May be. In this case, messages regarding bandwidth reservation / reservation / release are not transmitted / received between the wireless AP and the access controller, and resource management such as bandwidth reservation / reservation / release is performed within the access controller.

  The wireless AP is monitoring the timer, and if the next message (step 16 in FIG. 11) is not received within a predetermined time, the bandwidth reserved in step 5 is released (step 13 in FIG. 11).

  The SIP server that has transmitted and received ACK (steps 11 and 12 in FIG. 10) manages the call between the terminal 1 and the terminal 2 as a busy call. Since the bandwidth between the terminals 1 and 2 is determined at this time, the SIP server transmits a QoS ensuring request to the access controller in step 14 of FIG. At this time, the call state for the terminal 1 is QoS secured. After that, the bandwidth (resource) is secured in the wireless AP by the same sequence (step 15 to step 19 in FIG. 11) as the QoS reservation request sequence (step 3 to step 7 in FIG. 10). The voice communication between the terminals 1 and 2 is executed (step 20).

  FIG. 12 is a sequence diagram showing a process when a call is disconnected from the terminal 2 after step 20 in FIG. In steps 21 to 24, the SIP server disconnects the call by performing normal SIP processing. In step 25, the SIP server sends a QoS release request to the access controller. The access controller extracts the corresponding wireless AP (step 26) and transmits a QoS release request to the wireless AP (step 27). The wireless AP releases the bandwidth that has been reserved for the MS01 so far (step 28), returns a QoS release response to the access controller (step 29), and the access controller returns a QoS release response to the SIP server (step 30). . At this time, there is no call state such as “QoS secured” for the terminal 1, and “Register” indicating simply connected is recorded as the call state.

  FIGS. 13 to 15 are diagrams illustrating a sequence in a case where the terminal 1 under the wireless AP that is not in a congested state transmits to the terminal 2. Except for the difference in the SIP sequence caused by the exchange of the transmitting terminal and the receiving terminal, the same processing as that in FIGS. 10 to 12 is executed, and bandwidth reservation, bandwidth reservation, and bandwidth release are performed.

  With the above configuration, when the terminal 1 in communication with the counterpart terminal performs a handover from the wireless AP 10 to another wireless AP 20, the operations shown in FIGS. 16 and 17 are executed. 16 and 17 show a case where the registrar is included in the SIP server.

  In FIG. 16, it is assumed that communication is performed between the terminal 1 and the terminal 2 by performing a sequence such as step 1 in FIG. 10 to step 19 in FIG. 11 (step 1). Here, the terminal 1 moves from the subordinate of the wireless AP 10 to the subordinate of the wireless AP 20 (step 2). The terminal 1 transmits a reconnection request (Reassociation) to the wireless AP 20 (step 3), and the wireless AP 20 acquires and registers the MAC address (MSID) of the terminal 1 (step 4). The wireless AP 20 transmits a terminal registration request including the wireless AP 20 ID (AP02) and the terminal 1 MAC address (MS01) to the access controller (step 5). The access controller updates the registration by storing the ID (AP02) of the wireless AP 20 received from the wireless AP 20 in association with the MAC address (MS01) of the terminal 1 in the storage device (step 6). Note that the current call state for the terminal 1 is “QoS secured”. Then, the access controller returns a terminal registration response to the wireless AP 20 (step 7).

  In this specific example, when the access controller receives a terminal registration request relating to the terminal 1 that is “QoS secured”, the access controller does not receive a trigger from the SIP server, and the terminal 1 with respect to the wireless AP 10 before the handover. A QoS release request is transmitted (steps 8 and 9). Receiving this request, the wireless AP 10 releases the bandwidth for the terminal 1 and transmits a QoS release response to the access controller (steps 10 and 11).

  Subsequently, the access controller transmits a QoS ensuring request including MS01 and the necessary bandwidth to the wireless AP 20 (step 12 in FIG. 17). Since the necessary bandwidth between the terminal 1 and the terminal 2 has already been determined, the QoS reservation sequence is not performed.

  In step 13, the bandwidth is secured for the terminal 1 in the wireless AP 20, and a QoS ensuring response is transmitted to the access controller (step 14). Thereafter, a call is performed between the terminal 1 and the terminal 2 via the wireless AP 20.

  Since such an operation is performed, even when the terminal 1 is handed over, the access controller can hold information regarding the terminal after the handover.

  Next, processing related to balancing the number of terminals connected to the wireless AP in this specific example will be described. First, data stored in the database of the access controller will be described.

  FIG. 18 shows an example of terminal management data. In the example shown here, the terminal MAC address and the terminal SIP-URI are associated with each other and registered in advance in the access controller database as fixed values. Based on the data transmitted and received by the above-described sequence, the terminal is managed by recording the radio status, call status, CallID, and connection AP as needed.

  The “wireless state” in the data shown in FIG. 18 is data indicating the connection state between the terminal and the wireless AP. When the terminal and the wireless AP are in the connected state, “Link Up” is recorded, and when the terminal is in the disconnected state "Link Down" is recorded. Further, the ID of the wireless AP when in the connected state is recorded in “connected AP”.

  “Call state” is data indicating the state of the call, and “Register” is recorded when registered without a call connection, and “Unregister” is recorded when registration is deleted. In addition, when a QoS reservation request is received from the SIP server and the QoS reservation response is returned to the SIP server, "QoS reservation is in progress" is recorded, and after the QoS reservation response is returned to the SIP server, the QoS reservation request is received. "QoS reserved" is recorded until the QoS is received, and "QoS is being secured" is recorded and the QoS is secured when QoS is secured from when the QoS securing request is received until the QoS securing response is returned to the SIP server. In the state where QoS is secured after the response is returned to the SIP server, “QoS secured” is recorded.

  “CallID” records data when the “SIP state” is QoS reservation / QoS reservation / QoS reservation / QoS reservation, and sets a CallID for each call (SIP session). By referring to the data shown in FIG. 18, the access controller can determine which call consumes the resource of which wireless AP.

  FIG. 19 shows an example of wireless AP resource management data. The APID and the resource upper limit value are fixed value data registered in advance, and the resource amount in use is changed at any time.

  “APID” in FIG. 19 is a unique ID for each wireless AP, and is the same as the information registered in “connection AP” of the terminal management data. The “resource upper limit value” is a resource upper limit value that can be used in the wireless AP. The “resource usage amount” is a resource amount currently used in the wireless AP, and dynamically changes according to the number of calls of a terminal connected to the wireless AP. Based on the difference between this information and the “resource upper limit value”, the free resource amount can be determined, and it can be determined whether or not the wireless AP is congested. The wireless AP may hold wireless AP management data. When the wireless AP holds the wireless AP management data, the wireless AP performs congestion determination, and the congestion determination result is transmitted to the access controller. On the other hand, since the access controller holds this data, it is not necessary to provide functions such as congestion determination to the wireless AP.

  FIG. 20 shows an example of adjacent wireless AP management data. This data is data set in advance in the database, and indicates which wireless AP is adjacent to each wireless AP to be managed.

  FIG. 21 shows an example of connection terminal management data. This data indicates, for each wireless AP, the ID of the terminal connected to the wireless AP and the radio wave intensity of the terminal. The terminal connected to the wireless AP can be acquired by extracting data in the “Link up” state from the terminal data shown in FIG. Or it is good also as acquiring ID of the terminal in a wireless link connection state from wireless AP. The radio wave intensity can be acquired from the wireless AP by transmitting a radio wave intensity request including the MSID to the wireless AP. Note that the ID and radio wave intensity of a terminal in a wireless link connection state may be simultaneously acquired from the wireless AP.

  FIG. 22 shows an example of reconnection request rejection time management data. This data indicates a predetermined time when the wireless AP that has disconnected the wireless link from the terminal refuses reconnection from the terminal, and a time that has actually elapsed since the disconnection. If the terminal is disconnected from the wireless link, depending on the specifications of the terminal, the connection to the wireless AP that disconnected the wireless link may be retried. If the connection fails, connection to the adjacent wireless AP may be performed. By setting the connection request rejection time, even when the wireless AP receives a connection request again from the terminal, the wireless AP rejects the connection request within the reconnection request rejection time. That is, even if a connection request is received, the subsequent operation is not performed. Thereby, it becomes possible to prompt the disconnected terminal to connect to the adjacent wireless AP.

  FIG. 23 shows wireless link disconnection prohibition time management data. This data includes a predetermined radio link disconnection prohibition time for each terminal and an elapsed time elapsed since the terminal received the radio link disconnection from the wireless AP. Even if a certain terminal becomes a candidate for disconnection, the access controller refers to this data and disconnects the terminal if the elapsed time after disconnection of the terminal has not reached the radio link disconnection prohibition time. do not do.

  FIG. 24 shows terminal number balancing setting data. This data includes a cycle in which the flow shown in FIG. 5 is executed, a first reference value, and a second reference value. The terminal number balancing setting data also includes wireless AP information acquisition cycle and minimum radio wave intensity data as shown in FIG. The wireless AP information acquisition cycle is a cycle for acquiring information on terminals connected to the wireless link and information on the radio wave intensity, and the access controller acquires the information in this cycle and records it in the database. Further, the minimum radio wave intensity is a value used to extract a terminal to be disconnected in step 6 in FIG. 5, and a terminal having a radio wave intensity smaller than the minimum radio wave intensity is set as a candidate for a terminal to be disconnected. In other words, a terminal having a radio field strength equal to or higher than the minimum radio field strength is not targeted for disconnection.

  Next, processing for balancing the number of connected terminals between adjacent wireless APs in this specific example will be described. The access controller acquires terminal information and updates the terminal information in the database in accordance with the wireless AP information acquisition cycle shown in FIG.

  When the access controller determines that it is time to perform the balancing process based on the cycle shown in FIG. 24, the access controller executes a process based on the flow shown in FIG. 5 and determines a terminal to be disconnected. In this specific example, whether or not the terminal is in a communication state can be determined based on whether or not the call state is QoS secured. Therefore, when determining a terminal to be disconnected, those that have QoS secured are excluded. In addition, since it is not desirable to disconnect terminals that are being reserved or secured in QoS, only terminals whose call state is “Register” may be disconnected.

  However, in this specific example, the call connection is continued by changing the operation after reconnecting to another wireless AP after the terminal is disconnected to the same operation as that in the case of handover (steps 4 to 16 in FIG. 16). Therefore, it is not essential not to disconnect the terminal in a call state.

  The operation at the time of disconnection when the terminal to be disconnected is the terminal 1 connected to the wireless AP 10 will be described with reference to FIG.

  In FIG. 26, it is assumed that the terminal 1 is connected to the wireless AP 10, but is not in a call connection. Further, the wireless AP 20 is a wireless AP adjacent to the wireless AP 10, and it is assumed that the radio wave reachable range of the wireless AP 20 is within a range in which communication quality can be maintained during VoIP communication of the terminal 1 when viewed from the terminal 1.

  The access controller that has decided to disconnect the terminal 1 transmits a wireless link disconnection request including the MS01 and the reconnection request rejection time to the wireless AP 10 (step 1). The wireless AP 10 sets a reconnection request rejection time for the terminal 1 (step 2). Thereby, even when the wireless AP 10 receives the connection request from the terminal 1 again, the wireless AP 10 rejects the connection request within the reconnection request rejection time. That is, even if a connection request is received, the subsequent operation is not performed.

The wireless AP 10 that has received the wireless link disconnection request disconnects the wireless link by transmitting a wireless link disconnection instruction (Disassociation) to the terminal 1 (step 3). The terminal 1 disconnected from the wireless link transmits a connection request (Association) to the wireless AP 20 that is a wireless AP adjacent to the wireless AP 10 (step 4).
The wireless AP 20 acquires and registers the MAC address (MSID) of the terminal 1 (step 5). The wireless AP 20 transmits a terminal registration request including the wireless AP 20 ID (AP02) and the terminal 1 MAC address (MS01) to the access controller (step 6). The access controller updates the registration by storing the ID (AP02) of the wireless AP 25 received from the wireless AP 20 in association with the MAC address (MS01) of the terminal 1 in the storage device (step 7). Then, the access controller returns a terminal registration response to the wireless AP (step 8). As a result, the terminal 1 is registered in association with the wireless AP 20, and thereafter can send and receive calls via the wireless AP.

  FIG. 27 shows a configuration example of an apparatus that performs the above processing. FIG. 27 is a diagram for explaining a functional outline example of the SIP server 40, the access controller 30, the wireless AP 10, and the console 50.

  In addition to the call control function 41 for performing call control based on SIP, the SIP server 40 uses the registration / deletion of the terminal to / from the SIP server (registrar) as a trigger to perform URI registration (validation) with the access controller. / Access controller that has a function to make a request for QoS reservation / reservation / release to the access controller by making a request of / deletion (invalidation) and triggering a SIP message (INVITE / BYE / response, etc.) An interface function 42 is provided.

The access controller 30 performs processing corresponding to each request received from the SIP server 40, and transmits an answer to the SIP server with respect to the SIP server interface function 31,
A terminal information acquisition unit 36 that acquires terminal information such as radio wave intensity and stores it in the database 35, a disconnected terminal determination unit 37 that determines a terminal to be disconnected, a terminal control unit 38 that transmits a request for disconnecting a terminal, a wireless A wireless AP interface function 33 that performs processing corresponding to a terminal registration / deletion request received from the AP, a console interface function 34 that sets various data in the database 35 according to input from the console, and a database 35 ing.

  Further, in addition to the wireless AP function 11 inherent to the wireless AP, the wireless AP 10 has an anti-access controller interface function 12 that makes a terminal registration / deletion request to the access controller 30 triggered by the connection / disconnection of the terminal to / from the wireless AP. Have.

  The console 50 has a user interface function 51 that receives an input from the operator and an anti-access controller interface function 52 that transmits setting information to the access controller.

  The SIP server and the access controller are realized by installing programs for realizing the above functions in a computer having a CPU, a storage device, a communication device, and the like.

  Next, a detailed functional configuration of the access controller 30 will be described with reference to FIG. As shown in FIG. 28, the access controller 30 has a database 35, a SIP cooperation I / F 60, a resource management function 70, a data management function 80, a wireless AP management function 90, a terminal management function 100, and a wireless AP cooperation I / F 110. ing.

  Hereinafter, the function of each functional unit will be described in more detail.

  The SIP cooperation I / F 60 has a SIP request reception unit 61 and a SIP request return unit 62.

  The SIP request reception unit 61 includes a terminal registration request reception unit 64 and a resource request reception unit 65. The terminal registration request receiving unit 64 receives a terminal registration request from the registrar. Also, the terminal registration information is passed to the terminal registration unit (application layer) 101. The resource request receiving unit 65 receives a resource request from the SIP server 40 and requests a resource operation from the resource reservation / release unit 71 according to the resource request type (reservation / reservation + notification / reservation / release).

  The SIP request return unit 62 includes a terminal registration request return unit 66 and a resource request return unit 67. The terminal registration request return unit 66 returns the result of the request to the terminal registration request reception unit 64 to the registrar, and requests a resource request. The return unit 67 returns the request result to the resource request receiving unit 65 to the SIP server 40.

  The resource management function 70 includes a resource reservation / release unit 71 and a resource state change monitoring unit 72. The resource reservation / release unit 71 requests a resource operation from the data update unit 81 according to the resource request type (reservation / reservation / release). In addition, congestion is determined according to the amount of free resources. For example, if the value obtained by subtracting the resource amount in use from the upper limit resource amount is equal to or less than the requested resource amount, it is determined that congestion is occurring.

  The data management function 80 has a data update unit 81. The data update unit 81 reads / adds / updates / deletes data from the database 35. Also, mutual conversion between SIP-URI and terminal MAC address is performed. The wireless AP management function 90 includes a wireless AP / resource registration unit 91, a terminal information acquisition unit 92, and a disconnected terminal determination unit 93. The wireless AP / resource registration unit 91 sets the wireless AP registration and the resource upper limit value for the wireless AP in the database 35 based on an instruction from the console 50. In addition, the terminal information acquisition unit 92 performs processing for acquiring terminal information such as radio wave intensity and stores it in the database 35. The disconnected terminal determination unit 93 determines a terminal to be disconnected using data stored in the database 35.

  The terminal management function 100 includes a terminal registration unit (application layer) 101 and a terminal registration unit (data link layer) 102. The terminal registration unit (application layer) 101 receives the SIP-URI of the resource management target terminal from the terminal registration request reception unit 64 and requests the data update unit 81 to perform data registration. With this process, SIP-URI is validated in this system. The terminal registration unit (data link layer) 102 receives the MAC address of the resource management target terminal from the terminal MAC registration request reception unit 111 and requests the data update unit 81 to perform data registration. By this processing, the terminal MAC address is validated in this system.

  The wireless AP cooperation I / F 110 has a terminal MAC registration request receiving unit 111. The terminal MAC registration request accepting unit 111 accepts an event triggered by a terminal event (Association / Disassociation / Reassociation) that occurs in the wireless AP, and responds to the terminal registration unit (data link layer) 102 according to the type of the event. Request registration / deletion / re-registration of terminal MAC address. Further, the wireless AP cooperation I / F 110 includes a terminal control unit 112 that transmits a request for disconnecting the terminal. Further, the wireless AP cooperation I / F 110 performs a request transmission for acquiring information such as radio wave intensity to the wireless AP and a process of receiving information according to the request. The above-described configuration is only an example. Any configuration may be used as long as the operation described in this embodiment can be realized.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

It is a structural example of the conventional radio | wireless communications system. It is a figure which shows an example of the radio | wireless communications system in embodiment of this invention. It is a general | schematic functional block diagram of an access controller. It is a figure for demonstrating the operation | movement outline | summary of the radio | wireless communications system in embodiment of this invention. It is a flowchart of a terminal number balancing process. It is a numerical example which calculates | requires the cutting | disconnection candidate terminal number of object wireless AP. It is a figure which shows the example of a radio | wireless IP telephone system. It is a sequence diagram for registering the terminal 1 in the access controller. It is a sequence diagram for deleting the terminal 1 registered from the access controller. FIG. 10 is a sequence diagram when an incoming request is made from a terminal 2 to a terminal 1 under a wireless AP that is not congested. FIG. 10 is a sequence diagram when an incoming request is made from a terminal 2 to a terminal 1 under a wireless AP that is not congested. FIG. 10 is a sequence diagram when an incoming request is made from a terminal 2 to a terminal 1 under a wireless AP that is not congested. FIG. 11 is a sequence diagram when a terminal 1 under a wireless AP that is not congested transmits to a terminal 2; FIG. 11 is a sequence diagram when a terminal 1 under a wireless AP that is not congested transmits to a terminal 2; FIG. 11 is a sequence diagram when a terminal 1 under a wireless AP that is not congested transmits to a terminal 2; It is a sequence diagram which shows the operation | movement at the time of a hand-over. It is a sequence diagram which shows the operation | movement at the time of a hand-over. It is an example of terminal management data. It is an example of wireless AP resource management data. It is an example of adjacent wireless AP management data. It is an example of connection terminal management data. It is an example of reconnection request refusal time management data. It is an example of radio link disconnection prohibition time management data. It is an example of terminal number balancing setting data. It is an example of terminal number balancing setting data. It is a sequence diagram which shows the operation | movement at the time of a terminal disconnection. It is a figure for demonstrating the function outline | summary of each apparatus. 3 is a detailed functional configuration diagram of an access controller 30. FIG.

Explanation of symbols

1, 2 Terminal 10, 20 Wireless AP
11 Wireless AP Function 12 Access Controller Interface Function 30 Access Controller 31 SIP Server Interface Function 33 Wireless AP Interface Function 34 Console Interface Function 35 Database 36 Terminal Information Acquisition Unit 37 Disconnected Terminal Determination Unit 38 Terminal Control Unit 40 SIP Server 41 Call control function 42 Access controller interface function 50 Console 51 User interface function 52 Access controller interface function 60 SIP linkage I / F
70 Resource Management Function 80 Data Management Function 90 Wireless AP Management Function 100 Terminal Management Function 110 Wireless AP Cooperation I / F

Claims (5)

A connection terminal number balancing device for balancing the number of terminals connected to each wireless AP between a plurality of adjacent wireless APs,
From each wireless AP, terminal information acquisition means for acquiring the identification information of the terminal connected to the wireless AP and the radio wave intensity of the terminal, and storing it in the storage means;
A first reference value comparing means for comparing a number of terminals connected to the wireless AP with a predetermined first reference value with respect to a certain wireless AP;
If it is determined by the first reference value comparison means that the number of terminals connected to the wireless AP exceeds the first reference value, the wireless AP and the wireless AP adjacent to the wireless AP The average value of the number of connected terminals between them or a value obtained by converting the average value into an integer is calculated, and a predetermined second value is obtained from a value obtained by subtracting the value from the number of terminals connected to the wireless AP. When the value obtained by subtracting the reference value is a positive value, a disconnected terminal number determining unit that determines the number of terminals that are candidates for disconnecting from the wireless AP based on the value;
Referring to the storage means, from all or a part of the terminals connected to the wireless AP, in a descending order of radio field intensity, a terminal extracting means for extracting a maximum number of terminals corresponding to the number of terminals;
And a terminal disconnection unit that disconnects all or part of the terminals extracted by the terminal extraction unit from the wireless AP.   2. The connection terminal number balancing device according to claim 1, wherein the connection terminal number balancing device does not disconnect a terminal having a radio field intensity greater than a predetermined radio field intensity from the wireless AP.   The connected terminal number balancing device according to claim 1 or 2, wherein the connected terminal number balancing device does not disconnect a terminal in communication with another terminal from the wireless AP.   The connected terminal number balancing device is a terminal that is disconnected from another wireless AP before being connected to the wireless AP, and is disconnected from the other wireless AP. 4. The connected terminal number balancing device according to claim 1, wherein a terminal for which a predetermined time has not elapsed has not been disconnected. 5. A connection terminal number balancing method in which a connection terminal number balancing device for balancing the number of terminals connected to each wireless AP is executed between a plurality of adjacent wireless APs. A terminal information acquisition step of acquiring the identification information of the terminal connected to the wireless AP and the radio field intensity of the terminal and storing it in the storage means;
A first reference value comparison step for comparing the number of terminals connected to the wireless AP with a predetermined first reference value for a wireless AP;
In the first reference value comparison step, when it is determined that the number of terminals connected to the wireless AP exceeds the first reference value, the wireless AP and the wireless AP adjacent to the wireless AP are The average value of the number of connected terminals between them or a value obtained by converting the average value into an integer is calculated, and a predetermined second value is obtained from a value obtained by subtracting the value from the number of terminals connected to the wireless AP. When the value obtained by subtracting the reference value is a positive value, the number of disconnected terminals is determined to determine the number of terminals that are candidates for disconnecting from the wireless AP based on the value;
Referring to the storage means, from all or a part of the terminals connected to the wireless AP, in a descending order of radio field strength, extracting a maximum number of terminals corresponding to the number of terminals;
And a terminal disconnecting step of disconnecting all or part of the terminals extracted in the terminal extracting step from the wireless AP.

Images