JP2007110507A - Radio communication system, communication device, and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve use efficiency of a band of a network to be used by a radio communication system such as a radio LAN system. <P>SOLUTION: Multicast groups where a terminal station as a receiving station (receiver) or transmitting station (sender) for multicast data is present are identified by the radio LAN communication parts, and based upon identification results, it is determined which radio LAN communication part the terminal station is connected to. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication system, a communication device, and a wireless communication method including a communication device including a plurality of wireless units and a terminal device accommodated in the communication device.

  Conventionally, a bridge in a wired LAN monitors IGMP (Internet Group Multicast Protocol), which is a multicast management protocol. Then, the data from the “sender” that is the multicast data transmission station is transmitted only to the port where the “receiver” that is the multicast data reception station exists. This improves the bandwidth utilization efficiency in the network.

  On the other hand, a base station in a wireless LAN includes the number of terminal stations that are receivers in a beacon to be transmitted, and the terminal station is connected to a base station that has transmitted a beacon having a large number of terminal stations that are receivers. This improves the bandwidth utilization efficiency in the network (see, for example, Patent Document 1).

Also, register the base station that is sending the multicast data to the router, the terminal station inquires the base station that is sending the multicast data that the local station wants to join to the router, and connects to the registered base station. ing. Thereby, the use efficiency of the band in the network is improved (for example, refer to Patent Document 2).
JP 2001-217769 A JP 2004-015435 JP

  In the conventional technology in the wireless LAN as described above, a terminal station is connected to a base station having many terminal stations that are receivers.

  However, when receivers are already connected to multiple base stations, the receivers are not concentrated on a single base station, and multicast data continues to be transmitted to multiple base stations. There was a problem in that it should not.

  In addition, there is a problem in that it is not possible to flexibly cope with a change in the multicast group or when there are a plurality of multicast groups.

  Further, there is a problem in that it is not possible to flexibly cope with a case where there is a margin in the band, or conversely, there is no margin in the band.

  An object of the present invention is to solve the problems in the conventional technology described above and further improve the bandwidth utilization efficiency.

  The present invention is a wireless communication method for a wireless communication system including a communication device including a plurality of wireless units and a terminal device accommodated in the communication device, and is performed by each of the plurality of wireless units. An identification step for identifying group communication, and a determination step for determining a radio unit to be connected to a terminal device accommodated in the communication device and participating in the first group communication based on the identification result in the identification step It is characterized by that.

  In addition, the present invention is a communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units, the identification unit identifying group communication performed by each of the plurality of wireless units, and the identification unit And determining means for determining a radio unit to be connected to a terminal device that is accommodated in the communication device and participates in the first group communication based on the identification result.

  Further, the present invention is a communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units, and a determination unit that determines a wireless unit to which a plurality of terminal devices participating in the first group communication are connected, A plurality of terminal devices that perform the first group communication, based on the determination by the determination unit, include an execution unit that executes a process for connecting to the wireless unit determined by the determination unit. .

  According to another aspect of the present invention, there is provided a wireless communication method for a communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units, and determines a wireless unit to which a plurality of terminal devices participating in the first group communication are connected. The determination step and a plurality of terminal devices that perform the first group communication include an execution step of executing a process for connecting to the wireless unit determined in the determination step.

  Furthermore, the present invention is a wireless communication system including a communication device including a plurality of wireless units and a terminal device accommodated in the communication device, and the communication device is performed by each of the plurality of wireless units. Identification means for identifying the group communication being determined, and determination means for determining a radio unit to be connected to a terminal apparatus accommodated in the communication device and participating in the first group communication based on the identification result of the identification means The terminal device has switching means for switching the connection to the radio unit determined by the determining means.

  According to the present invention, for example, the terminal device can be accommodated in one of the group communications performed by each of the plurality of radio units, and the bandwidth utilization efficiency in the network can be improved.

  The best mode for carrying out the invention will be described below in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating an example of a configuration of a wireless LAN system to which the wireless communication method according to the first embodiment is applied. In FIG. 1, reference numeral 101 denotes a base station (AP) having a wireless LAN communication function defined by IEEE 802.11x, a wired LAN communication function defined by IEEE 802.3, and a relay function between the wireless LAN and the wired LAN. . The AP 101 includes a plurality of wireless LAN communication units, and is configured to be able to construct a plurality of BSSs (Basic Service Sets) using a plurality of wireless channels.

  102 and 103 are both terminal stations (STAs) having a wireless LAN communication function defined by IEEE 802.11x. The terminal stations 102 and 103 can connect to the AP 101 using the wireless LAN communication function and communicate with other terminal stations or devices existing in the wired LAN.

  The STAs 102 and 103 have a multicast group management function based on IGMP defined by RFC1112 or RFC2236. Also, as shown by the dotted line in FIG. 1, if there is a server in the wired LAN and this is a multicast sender, the STA 11 and STA 12 become multicast receivers and can receive multicast data. A router exists between the AP 101 and the server (sender), but is not shown in FIG.

  Here, the internal configuration of the base station (AP) 101 and the internal configuration of the terminal station (STA) 102 will be described with reference to FIG. The internal configuration of the terminal station (STA) 103 is the same as that of the terminal station 102.

  FIG. 2 is a diagram illustrating an example of the internal configuration of the base station 101 and the terminal station 102. In FIG. 2A, reference numeral 201 denotes a control unit that controls the overall operation of the AP 101, and includes a CPU and its peripheral circuits. Reference numeral 202 denotes a work memory that the control unit 201 calls a control program and uses for work, and is constituted by a RAM. A program memory 203 stores a control program group including control programs that provide a wireless LAN communication function, a wired LAN communication function, and a relay function, and includes a ROM.

  Each of 204 to 206 is a wireless LAN communication unit that provides a wireless LAN communication function defined by IEEE 802.11x, and has at least a wireless LAN chip and an antenna. A wired LAN communication unit 207 provides a wired LAN function defined by IEEE 802.3, and includes at least a wired LAN chip and a cable connector. A system bus 208 connects the control unit 201, work memory 202, program memory 203, wireless LAN communication units 204 to 206, and wired LAN communication unit 207.

  In FIG. 2B, reference numeral 209 denotes a control unit that controls the overall operation of the STA 102, and includes a CPU and its peripheral circuits. Reference numeral 210 denotes a work memory used by the control unit 209 for calling a control program for work, and includes a RAM. Reference numeral 211 denotes a program memory that stores a control program group including a control program that provides a wireless LAN communication function, and includes a ROM.

  A wireless LAN communication unit 212 provides a wireless LAN communication function defined by IEEE 802.11x, and includes at least a wireless LAN chip and an antenna. Reference numeral 213 denotes a display unit that displays a screen to the user, and includes, for example, a TFT (Thin Film Transistor) liquid crystal panel. Reference numeral 214 denotes an input unit for inputting a user instruction, which is composed of an array of characters and keys assigned to commands. A system bus 215 connects the control unit 209, work memory 210, program memory 211, wireless LAN communication unit 212, display unit 213, and input unit 214.

  FIG. 3 is a diagram illustrating an example of a configuration of a multicast group monitoring event in the first embodiment. This multicast group monitoring event is output from the multicast group monitoring process for monitoring each of the wireless LAN communication units 204 to 206 to the wireless LAN communication unit switching process. Further, these processes will be described in detail.

  301 shown in FIG. 3 is a multicast group monitoring event, and is composed of four parameters: a port, a group address, a state, and a receiver address. Here, the port parameter indicates a wireless LAN communication unit in which an IGMP Report message is detected, and is set to a value of 0, 1, or 2. For example, when an IGMP report message is detected by the wireless LAN communication unit 204, this port parameter is set to 0 by the multicast group monitoring process. The group address parameter indicates a multicast address that is a target of the detected IGMP report or a multicast address for which no IGMP report has been detected, and an IP address is set.

  The status parameter indicates whether there is a terminal station participating in the multicast group, and is set to 0 when an IGMP report is detected by the multicast group monitoring process, and is set to 1 when it is not detected. The receiver address parameter indicates the address of the terminal station that transmitted the detected IGMP report, and the MAC address is set (and is not set in the event when it is not detected). That is, the MAC address of the terminal station that is the receiver that has joined or reported that it has joined the multicast group is set.

  Here, the multicast group monitoring process in the AP 101 will be described with reference to FIG. In this multicast group monitoring process, the MAC frames flowing through the wireless LAN communication units 204 to 206 are monitored, and an IGMP report transmitted from the terminal station and an IGMP query transmitted from a router in the wired LAN are detected. Then, the result of monitoring whether there is a terminal station participating in the multicast group is transmitted to the wireless LAN communication unit switching process.

  This multicast group monitoring process is a process that is started when the wireless LAN communication function of the AP 101 is initialized. The multicast group monitoring process is performed for the wireless LAN communication units 204 to 206. In this example, the process for the wireless LAN communication unit 204 will be described as an example.

  FIG. 4 is a flowchart showing the multicast group monitoring process. When the multicast group monitoring process is started, the process proceeds to step S401 and waits for arrival of a MAC frame received from the wireless LAN communication unit 204 and a MAC frame to be transmitted to the wireless LAN communication unit 204. Thereafter, when the MAC frame arrives, the process proceeds to step S402, where it is determined whether or not the content of the arrived MAC frame is related to IGMP. If it is an IGMP message, the process proceeds to step S403, and if not, the process returns to step S401. This process is a process of analyzing the IP header in the MAC frame and determining whether or not the protocol number is IGMP.

  In step S403, the contents of the IGMP message are analyzed to determine whether the IGMP report is transmitted by the terminal station or the IGMP query transmitted by the router. The IGMP report is a message indicating that the multicast group is participating (participating), and the IGMP query is a message indicating whether there is a receiver. Here, the message type field is analyzed to determine whether it is a report or a query. In this embodiment, the query is not a query for all groups, but a query in which a specific group is specified (Group-Specific Query). However, the present invention is not limited to this.

  If the result of step S403 is an IGMP report, the process proceeds to step S404, and if it is an IGMP query, the process proceeds to step S405. In step S404, the value of the state parameter in the multicast group monitoring event 301 is set to 0 (with receiver), and the process proceeds to step S406. In this process, it is determined that the presence of a multicast group receiver is confirmed by detecting the IGMP report.

  In step S405, a timer having a time corresponding to the maximum response time of the IGMP message (time allowed for transmitting a report to the query, waiting time) is started. Here, a timer for determining whether a report arrives within a predetermined time in response to a query from the router is started. In step S407, during the timer time set in step S405, it waits for the IGMP report from the terminal station to arrive at the monitored wireless LAN communication unit 204. Here, if it has arrived or if the timer time has been exceeded, the process proceeds to step S409, where it is determined whether a report has arrived or if the timer time has not been reached. As a result, if the report has not arrived even if the timer time is exceeded, the process proceeds to step S410, and the value of the status parameter in the multicast group monitoring event 301 is set to 1 (no receiver). That is, it means that there is no receiver of the multicast group specified by the query, and there is no receiver of the multicast group in the wireless LAN communication unit 204.

  Next, in step S406, other parameters are set for the multicast group monitoring event 301, the event is transmitted to the wireless LAN communication unit switching process, and the process proceeds to step S408. Here, 0 (1 and 2 in the case of the wireless LAN communication unit 205 and the wireless LAN communication unit 206, respectively) indicating the wireless LAN communication unit 204 being monitored is set in the port. The group address of the IGMP message (report or query) is set as the group address, and the MAC address of the terminal station that transmitted the report is set as the receiver only when the report is detected.

  In step S408, it is determined whether or not the processing is interrupted due to an error or a wireless LAN communication function being stopped. Here, if it is interrupted, the process is terminated, and if it is not interrupted, the process returns to step S401.

  In the first embodiment, a plurality of multicast group monitoring processes are configured to monitor a plurality of wireless LAN communication units, respectively, but a single multicast group monitoring process may be configured to collectively monitor. .

  Next, the wireless LAN communication unit switching table created and held by the wireless LAN communication unit switching process of the AP 101 will be described with reference to FIG.

  FIG. 5 is a diagram illustrating an example of a configuration of the wireless LAN communication unit switching table in the first embodiment. As shown in FIG. 5, the wireless LAN communication unit switching table 501 has an array structure having two members: a group address and a port.

  This group address member indicates a group address of a multicast group in which a terminal station connected to the AP 101 is a receiver, and is described by an IP address. The port member indicates which wireless LAN communication unit is transmitting data of the multicast group, and is a value indicating the port (0 is the wireless LAN communication unit 204, 1 is the wireless LAN communication unit 205, and 2 is the wireless LAN. Communication unit 206) is included. As a result, the AP 101 can list which wireless LAN communication units 204 to 206 transmit the multicast group.

  Next, the wireless LAN communication unit switching process for switching the wireless LAN communication unit will be described with reference to FIGS. First, a message exchanged between the AP 101 and the STA 102 when the wireless LAN communication unit is switched and a sequence chart thereof will be described with reference to FIG. The same applies between the AP 101 and the STA 103.

  6A shows a wireless LAN communication unit switching request message and a wireless LAN communication unit switching response message, and FIG. 6B shows a sequence thereof. In FIG. 6, reference numeral 601 denotes a wireless LAN communication unit switching request message transmitted from the AP 101 to the terminal station, and includes a switching destination wireless LAN communication unit address field. In the switching destination wireless LAN communication unit address field, the MAC address of the wireless LAN communication unit to be switched next by the terminal station is set. Reference numeral 602 denotes a wireless LAN communication unit switching response message, which includes a status field. In this status field, information indicating whether or not the terminal station responds to the switching request of the wireless LAN communication unit is set. For example, 0 is set for permission, and 1 is set for rejection.

  Note that the wireless LAN communication unit switching request 601 and the wireless LAN communication unit switching response 602 are configured as protocols higher than the IP layer in the first embodiment, and the transmission and reception follow the protocols higher than the IP layer. Shall. For example, when configured as an upper protocol of the IP layer, the IP address of the base station and the terminal station is appropriately set as the destination address and the source address of the IP layer, and transmission / reception is performed, but details thereof are omitted.

  Further, the present invention is not limited to this, and it is different which protocol is configured or which information is exchanged by handoff processing described later.

  Next, in the sequence 603 of (b) shown in FIG. 6, when the wireless LAN communication unit is switched in the AP 101, the AP 101 transmits a wireless LAN communication unit switching request 601 to the STA 102. Next, in sequence 604, the STA 102 determines whether or not to respond to the wireless LAN communication unit switching request 601, and returns a wireless LAN communication unit switching response 602 to the AP 101. Thereafter, in sequence 605, a handoff process that is a switching process of the wireless LAN communication unit is performed between the AP 101 and the STA 101.

  With regard to this handoff process, in the first embodiment, the STA 102 first disconnects from the wireless LAN communication unit that is the switching source of the AP 101, and then connects to the wireless LAN communication unit that is the switching destination of the AP 101. A series of operations. However, the present invention is not limited to this. For example, in an ESS (Extended Service Set) composed of a plurality of BSSs, a handoff function defined by IEEE 802.11 when moving from one BSS to another BSS may be used. In addition, a part of roaming technology between base stations defined by IEEE 802.11F can be applied to this.

  Next, wireless LAN communication unit switching processing (handoff processing) in the AP 101 and the STA 102 will be described with reference to FIGS.

  FIG. 7 is a flowchart showing the wireless LAN communication unit switching process in the AP 101. Note that this wireless LAN communication unit switching process is performed for the terminal station when it is necessary to switch the wireless LAN communication unit connected to the terminal station to another wireless LAN communication unit based on the monitoring result of the multicast group monitoring process. The wireless LAN communication unit switching request 301 is transmitted. The wireless LAN communication unit switching process is a process started when the AP 101 initializes the wireless LAN communication function.

  When the wireless LAN communication unit switching process is started, the process proceeds to step S701, and the wireless LAN communication unit switching table 501 is initialized. This process is a process for creating an empty wireless LAN communication unit switching table. Next, in step S702, the process waits for the multicast group monitoring event 301 to be transmitted from the multicast group monitoring process described above. When the multicast group monitoring event 301 is transmitted, the process proceeds to step S703.

  In step S703, the state parameter of the transmitted multicast group monitoring event 301 is analyzed to determine whether a receiver exists or does not exist. If it is 0 indicating that there is a receiver, the process proceeds to step S704. If it is 1 indicating that there is no receiver, the process proceeds to step S705. In other words, depending on whether or not there is a multicast data receiver, the switching of the wireless LAN communication unit and the processing related to the transmission of the multicast data are different thereafter, so this determination is made.

  In step S704, the group address parameter of the transmitted multicast group monitoring event 301 is analyzed, and it is determined whether or not the multicast group having the group address is to start transmission. If it is new, the process proceeds to step S706, and if not new, the process proceeds to step S707. Here, the group address parameter of the transmitted multicast group monitoring event 301 is compared with the group address member described in the current wireless LAN switching table. If it is not added to the group address member, it is determined to be new, and if it is added, it is determined not to be new.

  In step S705, the port member reported in the multicast monitoring event 301 is deleted from the wireless LAN communication unit switching table 501, and the process proceeds to step S708. Here, the group address member and port member of the wireless LAN communication unit switching table 501 are searched for those that match the group address parameter of the multicast group monitoring event 301 and also match the port parameter. Only the port member as a set is deleted. When the same multicast data is transmitted through a plurality of ports, other port members are not deleted. If no other port is transmitting, that is, if there are no more port members, it is deleted for each group address member (for each group). At this time, the AP 101 indicates that this multicast data is not transmitted in any wireless LAN communication unit.

  In step S706, the group address parameter and the port parameter reported in the multicast group monitoring event 301 are added as a group address member and port member combination of the wireless LAN communication unit switching table 501. Here, it is determined that the group is a new group from step S704, and the multicast data should not be transmitted to other ports. Therefore, it is a new addition, and a group address member and port member combination is added.

  In step S707, it is determined whether multicast data of the same multicast group as reported in the multicast group monitoring event 301 has already been transmitted on the same port. If the ports are the same, the process proceeds to step S710, and if not, the process proceeds to step S711. Here, it is determined from the wireless LAN communication unit switching table 501 whether there is any that matches the group address parameter of the multicast group monitoring event 301 and the port parameter. This determination is for performing the process of moving the terminal station to the port if there is another port already transmitting the same multicast data in the subsequent process.

  In step S708, since there is no receiver of the reported multicast group at the port reported in the multicast group monitoring event 301, transmission of multicast data is stopped, and the process proceeds to step S710. Here, in the wireless LAN communication unit corresponding to the port parameter of the multicast group monitoring event 301, transmission of multicast data corresponding to the group address parameter is stopped.

  In step S709, since it is determined that a multicast group receiver newly exists at the port reported in the multicast group monitoring event 301, transmission of multicast data is started, and the process proceeds to step S710. Here, in the wireless LAN communication unit corresponding to the port parameter of the multicast group monitoring event 301, transmission of multicast data corresponding to the group address parameter is started.

  In step S710, it is determined whether or not the process is interrupted due to an error or a wireless LAN communication function being stopped. Here, if it is interrupted, the process is terminated, and if it is not interrupted, the process returns to step S702.

  In step S711, it is determined that multicast data of the same multicast group as that reported in the multicast group monitoring event 301 has already been transmitted through another port. Therefore, in order to move the terminal station that is a receiver to the port, a wireless LAN communication unit switching request 601 is transmitted, and the process proceeds to step S712.

  Here, first, the wireless LAN switching table 501 is searched for a port transmitting multicast data of a multicast group that matches the multicast group parameter reported in the multicast group monitoring event 301. Next, a wireless LAN communication unit switching request 601 is transmitted to a terminal station having a MAC address that matches the receiver address parameter reported in the multicast group monitoring event 301. That is, this terminal station is a terminal station in which the MAC address of the searched port is set in the switching destination wireless LAN communication unit address.

  In step S712, the terminal station waits for the wireless LAN communication unit switching response 602 to be transmitted. If the wireless LAN communication unit switching response 602 is transmitted, the process proceeds to step S713. In step S713, the status field of the transmitted wireless LAN communication unit switching response 602 is analyzed to determine whether it is permitted or denied. Here, if 0 indicates permission, the process proceeds to step S710, and if 1 indicates rejection, the process proceeds to step S714. That is, depending on whether it is permitted or not, whether or not the switching of the wireless LAN communication unit actually occurs differs from the subsequent processing, so this determination is performed.

  In step S714, since the terminal station has indicated a refusal regarding the switching of the wireless LAN communication unit, the wireless LAN is informed that a port for maintaining the current connection of the terminal station and newly transmitting multicast data is required. It adds to the communication part switching table 501. With this addition, multicast data can also be received. Here, the group address member of the wireless LAN communication unit switching table 501 is searched for a match with the group address parameter of the multicast group monitoring event 301, and only the port member as the set is added.

  Before step S711, it is estimated from the transmission status at another port whether multicast data can be transmitted to the receiver at that port. If transmission is possible, the process proceeds to step S714 without switching the wireless LAN communication unit. If not, the process proceeds to step S711, and the wireless LAN communication unit may be switched in consideration of the wireless band. . For example, before step S711, it is measured how much radio bandwidth is used at the port that has already transmitted the multicast data. Then, based on the result, it is determined whether or not there is still a radio band for transmitting the multicast data at the current port. If the wireless band remains, the process may proceed to step S714, and if not, the process may proceed to step S711.

  FIG. 8 is a flowchart showing the wireless LAN communication unit switching process in the STA 102. In this wireless LAN communication unit switching process, based on a wireless LAN communication unit switching request 601 from the base station, it is determined whether or not to switch the connected wireless LAN communication unit to another wireless LAN communication unit. Then, a wireless LAN communication unit switching response 602 is transmitted to the base station as a reply as to whether or not to permit switching, and in the case of permission, the wireless LAN communication unit is subsequently switched. The wireless LAN communication unit switching process is a process started when the STA 11 initializes the wireless LAN communication function.

  When the wireless LAN communication unit switching process is started, the process proceeds to step S801, waits for the wireless LAN communication unit switching request 601 to be transmitted from the base station, and when the wireless LAN communication unit switching request 601 is transmitted, the process proceeds to step S802. move on.

  In step S802, the local station determines whether to permit switching of the wireless LAN communication unit in response to the wireless LAN communication unit switching request 601 from the base station (AP101). Here, if permitted, the process proceeds to step S803, and if denied, the process proceeds to step S804. In the first embodiment, the beacon of the switching destination wireless LAN communication unit can be received and switching is permitted if connection is possible, but the present invention is not limited to this.

  In step S803, a wireless LAN communication unit switching response 602 indicating permission is transmitted to the base station, and the process proceeds to step S805. Here, a wireless LAN communication unit switching response 602 in which 0 indicating permission of switching is set in the status field is transmitted to the base station.

  In step S804, a wireless LAN communication unit switching response 602 indicating rejection is transmitted to the base station, and the process proceeds to step S806. Here, a wireless LAN communication unit switching response 602 in which 1 indicating switching rejection is set in the status field is transmitted to the base station.

  In step S805, the connection is switched from the currently connected switching source wireless LAN communication unit to the switching destination wireless LAN communication unit specified in the switching destination wireless LAN communication unit address field of the wireless LAN communication unit switching request 601. Perform handoff processing. As this handoff processing, it is a basic series of processing that first disconnects the base station switching source wireless LAN communication unit and then connects to the base station switching destination wireless LAN communication unit. The present invention is not limited to this. For example, in an ESS composed of a plurality of BSSs, a handoff function defined by IEEE 802.11 when moving from one BSS to another BSS may be used. In addition, a part of roaming technology between base stations defined by IEEE 802.11F can be applied to this.

  In step S806, it is determined whether or not the process is interrupted due to an error or a wireless LAN communication function being stopped. Here, if it is interrupted, the process is terminated, and if it is not interrupted, the process returns to step S801.

  FIG. 9 is a diagram for explaining a handoff operation according to the first embodiment. In FIG. 9, in 901, the STA 102 is connected to the wireless LAN communication unit 204 of the AP 101, and is a receiver of the multicast address 244.1.1.1. The multicast sender is a server indicated by a dotted line. At this time, in 902, the STA 103 is connected to the wireless LAN communication unit 205 of the AP 101 and transmits an IGMP report to become a receiver of the multicast address 244.1.1.1.

  In response to this, in 903, the AP 101 transmits to the STA 103 a wireless LAN communication unit switching request 601 in which the wireless LAN communication unit 204 is set in the switching destination wireless LAN communication unit address field. In step 904, the STA 103 returns a wireless LAN communication unit switching response 602 in which 0 indicating permission of switching is set in the status field to the AP 101.

  Next, in 905, the STA 103 is disconnected from the wireless LAN communication unit 205 and connected to the wireless LAN communication unit 204. As a result, in 906, the STA 103 is connected to the wireless LAN communication unit 204 of the AP 101 and becomes a receiver of 244.1.1.1. In the wireless LAN communication unit 205 and the wireless LAN communication unit 206, since there is no receiver, transmission of the multicast data of 244.1.1.1 is stopped.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described in detail with reference to the drawings.

  FIG. 10 is a diagram illustrating an example of a configuration of a wireless LAN system to which the wireless communication method according to the second embodiment is applied. In FIG. 10, reference numeral 1001 denotes a base station (AP) having a wireless LAN communication function defined by IEEE 802.11x, a wired LAN communication function defined by IEEE 802.3, and a relay function between the wireless LAN and the wired LAN. . The AP 1001 includes a plurality of wireless LAN communication units and is configured to be able to construct a plurality of BSSs using a plurality of wireless channels.

  Reference numeral 1002 denotes a terminal station (STA) having a wireless LAN communication function defined by IEEE 802.11x. The STA 1002 can connect to the AP 1001 using a wireless LAN communication function and communicate with other terminal stations or devices existing in the wired LAN.

  The STA 1002 has a multicast group management function based on IGMP defined by RFC1112 or RFC2236. Also, as shown by the dotted line in FIG. 10, if a server exists as a wireless LAN terminal station and is a multicast sender, the STA 1002 becomes a multicast receiver and can receive multicast data. is there.

  The internal configurations of the AP 1001 and the STA 1002 are the same as the internal configurations of the first embodiment described with reference to FIG.

  Next, a multicast group list created and held by the multicast group monitoring process of the AP 1001 will be described with reference to FIG. As in the first embodiment, the multicast group monitoring process is a configuration in which a single multicast group monitoring process collectively monitors a plurality of multicast group monitoring processes even when a plurality of wireless LAN communication units are monitored. But it ’s okay.

  FIG. 11 is a diagram illustrating an example of a configuration of a multicast group list in the second embodiment. In FIG. 11, reference numeral 1201 denotes a multicast group list having a list structure having group address members. The multicast group list 1201 is created and held for each of the wireless LAN communication units 204 to 206 of the AP 1001.

  This group address member indicates the group address of the multicast group in which the terminal station as the receiver exists in the wireless LAN communication unit 204 of the AP 1001, and is described by an IP address. As a result, the AP 1001 can list which multicast group the wireless LAN communication unit 204 is transmitting.

  Next, multicast group monitoring processing in the AP 1001 will be described with reference to FIG. In this multicast group monitoring process, the MAC frame flowing through the wireless LAN communication units 204 to 206 is monitored, and the IGMP report transmitted from the terminal station and the IGMP query transmitted from the router existing in the wired LAN are detected. Furthermore, transmission of multi-multicast data is started or stopped depending on whether or not there is a receiver, and a list of multicast groups transmitting multicast data is held in the multicast group list.

  This multicast group monitoring process is a process that is started when the wireless LAN communication function of the AP 1001 is initialized. The multicast group monitoring process is performed for the wireless LAN communication units 204 to 206. In this example, the process for the wireless LAN communication unit 204 will be described as an example.

  FIG. 12 is a flowchart showing the multicast group monitoring process. When the multicast group monitoring process is started, the process proceeds to step S1301, and the multicast group list is initialized. Here, an empty multicast group list is created. Next, in step S1302, it waits for the arrival of the MAC frame received from the wireless LAN communication unit 204 and the MAC frame to be transmitted to the wireless LAN communication unit 204. Thereafter, when the MAC frame arrives, the process proceeds to step S1303, where it is determined whether or not the content of the arrived MAC frame is related to IGMP. If it is an IGMP message, the process proceeds to step S1304, and if not, the process returns to step S1302. This process is a process of analyzing the IP header in the MAC frame and determining whether or not the protocol number is IGMP.

  In step S1304, the contents of the IGMP message are analyzed to determine whether it is an IGMP report transmitted by the terminal station or an IGMP query transmitted by the router, as in the first embodiment. If the result of step S1304 is an IGMP report, the process proceeds to step S1305, and if it is an IGMP query, the process proceeds to step S1306. In step S1305, the IGMP message is analyzed, and it is determined whether or not the multicast group having the group address is to start transmission. If it is new, the process proceeds to step S1307, and if not new, the process proceeds to step S1308. This process compares the group address field of the IGMP report with the group address member described in the current multicast group list. If it is not added to the group address member, it is regarded as new, and if it is added, it is not new. to decide.

  In step S1306, a timer corresponding to the maximum response time of the IGMP message is started as in the first embodiment. In step S1309, it waits for the IGMP report from the terminal station to arrive at the monitored wireless LAN communication unit 204 for the timer time set in step S1306. Here, if it has arrived or if the timer time has been exceeded, the process advances to step S1311 to determine whether a report has arrived or if it has not been reached even if the timer time has been exceeded. As a result, if the report arrives, the process proceeds to step S1308, and if the report does not arrive even if the timer time is exceeded, the process proceeds to step S1312. That is, if the report does not arrive even if the timer time is exceeded, there is no multicast group receiver specified by the query.

  Next, in step S1312, the multicast group having no receiver indicated by the IGMP message is deleted from the group address member of the multicast group list. Here, the IP address indicated in the group address field of the IGMP query is deleted from the group address member of the multicast group list. In this case, the AP 1001 indicates that this multicast data is not transmitted. In step S1313, since it is determined that there is a multicast group in which no receiver exists in the wireless LAN communication unit 204, transmission of multicast data of the multicast group is stopped. This process is a process for stopping the transmission of multicast data corresponding to the group address field of the IGMP query in the wireless LAN communication unit 204.

  In step S1307, a process of adding a new multicast group indicated by the IGMP message to the group address member of the multicast group list is performed. Here, the IP address indicated in the group address field of the IGMP report is added to the group address member of the multicast group list. In step S1310, since it is determined that there is a new multicast group receiver in the wireless LAN communication unit 204, transmission of multicast data is started. Here, the wireless LAN communication unit 204 starts transmission of multicast data corresponding to the group address field of the IGMP report.

  In step S1308, it is determined whether or not the processing is interrupted due to an error or a wireless LAN communication function being stopped. Here, if it is interrupted, the process is terminated, and if it is not interrupted, the process returns to step S1302.

  FIG. 13 is a diagram illustrating a configuration of a MAC frame transmitted from the AP 1001. In FIG. 13, reference numeral 1401 denotes a MAC frame format of the management frame, and a beacon frame information element is stored in the frame body. Reference numeral 1402 denotes a multicast group information element of the beacon frame, which includes an element ID field, a length field, and a group address field.

  The element ID field is used to identify that it is a multicast group information element, and has a unique value for each information element. In this example, the element ID for the multicast group information element is 255. It should be noted that other values may be used as long as the element ID does not overlap with other element IDs defined by IEEE 802.11.

  The length field is used to indicate the data length of the contents of the multicast group information element, and stores the total byte length of the group address field. The group address field is composed of a plurality of group addresses, and a plurality of 4-byte group addresses are listed.

  The above-described multicast group information element is included in the beacon and transmitted by the AP 1001 beacon transmission process. The multicast group information element is used to indicate to the terminal station a multicast group in which the base station is transmitting multicast data.

  Here, a beacon transmission process in which the AP 1001 transmits a beacon frame and notifies the STA 1002 of the multicast group will be described with reference to FIG.

  FIG. 14 is a flowchart showing a beacon transmission process in which the AP 1001 transmits a beacon from the wireless LAN communication unit 204. The beacon transmission process is started when the wireless LAN communication unit 204 of the AP 1001 transmits a beacon at a predetermined interval.

  First, when the beacon transmission process is started, the process proceeds to step S1501, and the multicast group list is referred to. Here, with reference to the multicast group list, the wireless LAN communication unit 204 confirms which multicast group's multicast data is being transmitted.

  Next, in step S1502, a multicast group information element is created. Here, the group addresses described in the multicast group list are sorted in order from the smallest value, listed in the group address field of the multicast group information element, and the length and element ID are set.

  Next, in step S1503, the entire beacon frame including the multicast loop information element in the frame body of the beacon frame and further including the frame header is generated and transmitted at a predetermined interval (the description is omitted), and this process ends. .

  Next, a connection prohibiting process for prohibiting a connection from a terminal station by the wireless LAN communication unit 204 in the AP 1001 will be described with reference to FIG. This connection prohibition process is started when the AP 1001 wireless LAN communication function is initialized.

  FIG. 15 is a flowchart illustrating a connection prohibition process according to the second embodiment. First, when the connection prohibition process is started, the process proceeds to step S1601 and waits for a MAC frame received by the wireless LAN communication unit 204 to arrive. Thereafter, when the MAC frame arrives, the process proceeds to step S1602, where the arrived MAC frame is analyzed to determine whether it is multicast data. If the data is multicast data, the process proceeds to step S1603. If the data is not multicast data, the process proceeds to step S1604. Here, it is determined whether or not the destination address of the arrived MAC frame is a MAC address corresponding to the multicast address.

  In the second embodiment, the MAC address of the multicast group having the IP address 224.1.1.1 corresponds to 01-00-5E-01-01-01. Also, it shall conform to the standard group MAC address defined in ISO / IEC TR 11802.2.

  In step S1603, it is determined whether or not the measurement (described later) in step S1605 has been performed regarding transmission of multicast data of the arrived multicast group. If the measurement has been completed, the process proceeds to step S1604. If the measurement has not been completed, the process proceeds to step S1605. Here, it is determined that processing (described later) has already been performed on the measured multicast group, and processing is not performed repeatedly.

  In step S1604, it is determined whether or not the process is interrupted due to an error or a wireless LAN communication function being stopped. Here, if it is interrupted, the process is terminated, and if it is not interrupted, the process returns to step S1601.

  Next, in step S1605, the wireless bandwidth necessary for transmitting the arrived multicast data and the remaining wireless bandwidth allowed by the wireless LAN communication unit 204 are measured. Then, it is determined that this multicast group has been measured, and the process proceeds to step S1606. Here, the arrived multicast data is data transmitted by the multicast sender. First, a radio band necessary for transmission of multicast data is measured. The rate at which this multicast data is transmitted within a certain time is measured. As a result, for example, it is measured that 40% of the entire radio band is required. Next, the remaining unused radio band is measured. Similarly, it is measured how long the MAC frame is not transmitted within a certain time. As a result, for example, it is measured that 20% of the entire radio band remains.

  Next, in step S1606, when a terminal station serving as a receiver of the arrived multicast data appears, it is determined whether or not it can be accepted. In this process, when a terminal station serving as a receiver appears, the wireless LAN communication unit 204 must be used to transfer the data transmitted by the sender to the receiver. It is a process to judge. That is, the determination is made based on whether or not the wireless band for receiving the multicast data transmitted by the sender and the equivalent wireless band remain. For example, when 40% of the entire radio band is used by the sender, it is necessary to leave 40% of the band in order to be able to accept a terminal station as a receiver. When the remaining is 20% of the entire radio band, the terminal station serving as the receiver determines that it is not acceptable.

  Needless to say, the bandwidth measurement and determination in steps S1605 and 1606 are not limited to this.

  In step S1607, since it is determined that the terminal station serving as a receiver cannot be accepted, connection is prohibited so that no more terminal stations can be connected to the wireless LAN communication unit 204. Here, after that, a response indicating connection refusal is sent back to the terminal station that has made a connection request to the wireless LAN communication unit 204.

  In the second embodiment, the simple connection is prohibited, but the present invention is not limited to this. For example, more advanced processing for confirming that it is surely a receiver of the multicast group may be added. In addition, when a bandwidth application for receiving the multicast group is made by a terminal station using a technology defined in IEEE 802.11e, it may be rejected.

  Further, although the connection prohibition release process is not shown, the release process may be performed in the following cases. For example, when the sender is disconnected from the wireless LAN communication unit 204, when multicast data is no longer transmitted, when the remaining wireless band has changed and the connection need not be prohibited.

  FIG. 16 is a flowchart showing a connection process with a base station in a terminal station. This connection process is a process of receiving a beacon transmitted by a base station, analyzing a multicast group information element included in the beacon, determining a wireless LAN communication unit to be connected, and connecting. This connection process is performed when a connection with a base station is instructed from the user or application in the STA 1002 (the description is omitted).

  First, when the connection process with the base station is started, the process proceeds to step S1701, and a beacon transmitted by the base station is received. Here, the wireless LAN communication unit 212 scans all channels used in the wireless LAN function for a certain period of time, receives a beacon transmitted by the base station during that period, and determines a connection destination candidate For the sake of convenience, these are temporarily stored.

  Next, in step S1702, the group address field of the multicast group information element included in the received beacon is compared with the group address of the multicast group to which the local station is scheduled to participate. Here, the wireless LAN communication unit of the base station that has already transmitted the multicast data of the multicast group is found, and even if the local station becomes a receiver, the wireless LAN communication unit that does not increase the usage rate of the wireless band This is to identify candidates. Although not shown, if the multicast group to which the local station is to participate is not known at this time, the process proceeds to step S1706.

  Next, in step S1703, it is determined whether there are a plurality of beacons in which the group addresses of the multicast groups to which the local station is to participate, a single beacon, or a single beacon. If there is only one, the process proceeds to step S1704. If there is a plurality, the process proceeds to step S1705, and if there is not, the process proceeds to step S1706. Here, if there are a plurality, it is necessary to narrow down the connection destination candidates of the wireless LAN communication unit of the base station, so the processing is branched.

  In step S1704, since the number of connection destination candidates for the wireless LAN communication unit of the base station is narrowed down to one, processing for connecting to the wireless LAN communication unit of the base station that is transmitting this beacon is performed, and the processing ends. In step S1705, since there are a plurality of connection destination candidates for the wireless LAN communication unit of the base station, the wireless LAN of the base station transmitting the beacon having the smallest number of group address fields in the multicast group information element is selected. Connect to the communication unit. Here, when the local station becomes a receiver, the base station with a small number of multicast groups is transmitted as a wireless LAN communication unit that is likely to receive multicast data most comfortably without increasing the usage rate of the radio band. The wireless LAN communication unit is selected and connected.

  Furthermore, in step S1706, the wireless LAN communication unit of the base station with the few multicast groups being transmitted is selected and connected as the wireless LAN communication unit that is most likely to receive the multicast data.

  FIG. 17 shows an operation example of the second embodiment by the AP 1001 and the STA 1002 configured as described above. In FIG. 17, in 1801, the server indicated by the dotted line is the sender of the group address 244.1.1.1. At this time, at 1802, the multicast data transmitted by the sender is measured, and the wireless LAN communication unit 206 prohibits the subsequent connection of the terminal station.

  Further, in 1803, the AP 1002 transmits beacons including the multicast group information element from the wireless LAN communication unit 204, the wireless LAN communication unit 205, and the wireless LAN communication unit 206, respectively. At this time, since no wireless LAN communication unit has a receiver yet, no group address is listed in the multicast information element of any beacon.

  Subsequently, in 1804, the STA 1002 tries to connect to the wireless LAN communication unit 206 of the AP 1001, but is rejected by the AP 1001. In 1805, the STA 1002 connects to the wireless LAN communication unit 204 of the AP 1001.

  Subsequently, in 1806, the STA 1002 is connected to the wireless LAN communication unit 204 of the AP 1001, and becomes a receiver of 244.1.1.1.

  As a result, in 1807, a beacon in which the group address 244.1.1.1 is described in the multicast group information element is transmitted only by the wireless LAN communication unit 204. Thereafter, if there is a terminal station scheduled to participate in the same multicast group, the wireless LAN communication unit 204 is selected.

[Modification]
It goes without saying that the present invention can also be achieved by replacing the wireless LAN communication function defined by IEEE 802.11x that implements the functions of the above-described embodiments with other wireless communication functions.

  It goes without saying that this can also be achieved by replacing the IGMP monitoring process described above with an MLD (Multicast Listener Discovery) monitoring process compatible with IPv6.

  As described above, according to the embodiment, terminal stations that are receiving stations of the same multicast group are connected to the same wireless unit, and the number of wireless units that transmit multicast data is reduced. Can be improved.

  Also, the connection status of the terminal station that is the receiving station of the multicast group in each radio unit is monitored. Accordingly, it is possible to flexibly cope with the case where the multicast group is changed or when there are a plurality of multicast groups, and it is possible to improve the bandwidth utilization efficiency in the network.

  Furthermore, by considering the bandwidth usage status in each radio unit, it is possible to respond flexibly according to the case where there is a bandwidth, or conversely, when there is no bandwidth, and the bandwidth utilization efficiency in the network. Can be improved.

  The present invention supplies a recording medium in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or apparatus, and the program code stored in the recording medium by a computer (CPU or MPU) of the system or apparatus Is read and executed. It goes without saying that the object of the present invention can also be achieved by this.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, DVD, or the like can be used. .

  In addition, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the following cases are included. That is, when the OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing.

  Further, the program code read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. After that, based on the instruction of the program code, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing. Needless to say.

It is a figure which shows an example of a structure of the wireless LAN system to which the wireless communication system in 1st Embodiment is applied. It is a figure which shows an example of an internal structure of the base station 101 and the terminal station 102. FIG. It is a figure which shows an example of a structure of the multicast group monitoring event in 1st Embodiment. It is a flowchart which shows the multicast group monitoring process in 1st Embodiment. It is a figure which shows an example of a structure of the wireless LAN communication part switching table in 1st Embodiment. (A) is a message of a wireless LAN communication part switching request and a message of a wireless LAN communication part switching response, and (b) is a diagram showing their sequences. 7 is a flowchart showing a wireless LAN communication unit switching process in AP101. 7 is a flowchart showing wireless LAN communication unit switching processing in the STA. It is a figure for demonstrating the operation | movement of the handoff in 1st Embodiment. It is a figure which shows an example of a structure of the wireless LAN system to which the wireless communication system in 2nd Embodiment is applied. It is a figure which shows an example of a structure of the multicast group list | wrist in 2nd Embodiment. It is a flowchart which shows the multicast group monitoring process in 2nd Embodiment. It is a figure which shows the structure of the MAC frame transmitted from AP1001. 10 is a flowchart illustrating beacon transmission processing in which an AP 1001 transmits a beacon from a wireless LAN communication unit 204. It is a flowchart which shows the connection prohibition process in 2nd Embodiment. It is a flowchart which shows the connection process with the base station in a terminal station. It is a figure for demonstrating the operation example of AP1001 and STA1002 in 2nd Embodiment.

Explanation of symbols

101 Base station (AP)
102 Terminal station (STA)
103 Terminal Station (STA)
201 control unit 202 work memory 203 program memory 204 wireless LAN communication unit 205 wireless LAN communication unit 206 wireless LAN communication unit 207 wired LAN communication unit 208 system bus 209 control unit 210 work memory 211 program memory 212 wireless LAN communication unit 213 display unit 214 Input unit 215 System bus

Claims (19)

A wireless communication method of a wireless communication system including a communication device including a plurality of wireless units and a terminal device accommodated in the communication device,
An identification step for identifying group communication performed in each of a plurality of radio units;
A determination step of determining a wireless unit to be connected to a terminal device accommodated in the communication device and participating in the first group communication based on the identification result in the identification step;
A wireless communication method comprising:   The wireless communication method according to claim 1, wherein the group communication is communication with a terminal device that receives multicast data.   The wireless communication method according to claim 1, wherein the group communication is communication with a terminal device that transmits multicast data.   The wireless communication method according to claim 1, wherein the determination step is performed in consideration of a band usage state in the plurality of wireless units.   The wireless communication method according to claim 1, further comprising a transmission step of transmitting a request to the terminal device so as to switch to the wireless unit determined in the determination step.   The wireless communication method according to claim 1, further comprising a notification step of notifying the terminal device of identification information of group communication performed by each of the plurality of wireless units.   The wireless communication method according to claim 1, further comprising a switching step of switching the connection of the wireless unit to which the terminal device is connected to the wireless unit determined in the determining step.   The wireless communication method according to claim 6, wherein the terminal device includes a step of determining a wireless unit to be connected based on the group communication identification information notified in the notification step. A communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units,
Identification means for identifying group communication performed in each of a plurality of radio units;
A determination unit that determines a wireless unit to be connected to a terminal device that is accommodated in the communication device and participates in the first group communication based on the identification result in the identification unit;
A communication apparatus comprising:   The communication device according to claim 9, wherein the group communication is communication with a terminal device that receives multicast data.   The communication device according to claim 9, wherein the group communication is communication with a terminal device that transmits multicast data.   The communication apparatus according to claim 9, wherein the determination unit determines the bandwidth in consideration of a use situation of a band in the plurality of radio units.   The communication apparatus according to claim 9, further comprising a transmission unit that transmits a request to the terminal device so as to switch to the radio unit determined by the determination unit.   The communication device according to claim 9, further comprising notification means for notifying the terminal device of identification information of group communication performed by each of the plurality of wireless units. A communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units,
Determining means for determining a wireless unit to which a plurality of terminal devices participating in the first group communication are connected;
Based on the determination by the determination unit, a plurality of terminal devices that perform the first group communication execute processing for connecting to the wireless unit determined by the determination unit;
A communication apparatus comprising: A wireless communication method for a communication device that accommodates a terminal device wirelessly and includes a plurality of wireless units,
A determining step of determining a wireless unit to which a plurality of terminal devices participating in the first group communication are connected;
A plurality of terminal devices that perform the first group communication execute a process for connecting to the wireless unit determined in the determination step;
A wireless communication method comprising: A wireless communication system including a communication device including a plurality of wireless units and a terminal device accommodated in the communication device,
The communication device
Identification means for identifying group communication performed in each of a plurality of radio units;
A determination unit configured to determine a wireless unit to be connected to a terminal device accommodated in the communication device and participating in the first group communication based on the identification result in the identification unit;
The terminal device
A wireless communication system comprising switching means for switching connection to the wireless unit determined by the determining means.   A program for causing a computer to execute the wireless communication method according to claim 1 or 16.   The computer-readable recording medium which recorded the program of Claim 18.

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