JP2004350052A - Management node device, radio terminal, radio communication system, load distribution method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To distribute a load among respective radio access point devices while avoiding the wasteful use of a communication band between radio sections. <P>SOLUTION: A management node device grasps loads applied to a plurality of radio access point devices and a multicast group transmitted with a data block from each radio access point device, and then makes a decision whether the loads applied to respective radio access point devices are unbalanced or not. If the loads are unbalanced, at least one radio terminal in the multicast group transmitted with a data block from a radio access point device applied with the heaviest load is specified in the management node device, and the radio terminals pertaining to that multicast group are requested to switch connection to a radio access point device applied with the lightest load. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for distributing a load among a plurality of wireless access point devices.
[0002]
[Prior art]
In a wireless communication system having a plurality of wireless access point devices, the number of wireless terminals connected to each wireless access point device (hereinafter, “number of connected terminals”) and the amount of communication data to be processed (hereinafter, “traffic” There is a system configured so that loads such as ") are evenly distributed among wireless access point devices. For example, a wireless LAN (Local Area Network) whose standard is defined in IEEE (Institute of Electrical and Electronic Engineers) 802.11a, IEEE802.11b, and the like. In this wireless LAN, load information indicating a load and communication quality information indicating communication quality such as signal strength and connection quality in a wireless link are acquired for each wireless access point device, and a wireless terminal is newly connected. At times, the wireless access point device to connect to is determined based on the acquired information. By doing so, it is possible to ensure both a certain level of communication quality and load balancing between wireless access point devices.
[0003]
How the load distribution described above is performed in an actual wireless communication system will be described with reference to FIG. FIG. 15 is a diagram illustrating a configuration example of a wireless communication system that performs the load distribution described above. The wireless communication system shown in FIG. 15 includes a router 14 for receiving data transmitted from a backbone network such as the Internet, a network switch 13 for communicating with the router 14 via a communication line, and a network switch 13 for communicating with the router 14 via a communication line. Wireless access point devices 12A and 12B that communicate with the wireless communication device, and four wireless terminals 11A, 11B, 11C, and 11D that are connected to one of the wireless access point devices 12A and 12B and perform wireless communication. In the following, when it is not necessary to distinguish each of the wireless terminals 11A, 11B, 11C, and 11D, it is described as "wireless terminal 11." When there is no need to distinguish between the wireless access point devices 12A and 12B, the wireless access point devices 12A and 12B are described as “wireless access point devices 12”. The wireless terminals 11A and 11B are located near the wireless access point device 12A, and the wireless terminals 11C and 11D are located near the wireless access point device 12B. In addition, it is assumed that all of these four wireless terminals are at positions where they can be connected to both wireless access point devices 12A and 12B. Then, in the wireless communication system shown in FIG. 15, when none of the wireless terminals 11A, 11B, 11C, and 11D are communicating, the wireless access point devices 12A and 12B are hardly loaded. Hereinafter, it is referred to as “no-load state”).
[0004]
As described above, the wireless terminal 11 determines the wireless access point device to be connected based on the load on the wireless access point device and the communication quality between the wireless access point device. Since both the wireless access point devices 12A and 12B are in a no-load state, the wireless terminal 11 determines the connection destination substantially based only on the communication quality. Generally, the communication quality between a wireless terminal and a wireless access point device deteriorates as the distance between the wireless terminal and the wireless access point device increases. Therefore, in the above situation, the wireless terminals 11A and 11B connect to the wireless access point device 12A, and the wireless terminals 11C and 11D connect to the wireless access point device 12B.
[0005]
When only the wireless terminal 11A starts communication via the wireless access point device 12A in a state where such a connection is made, a load corresponding to the communication speed of the communication is applied to the wireless access point device 12A. For example, if the communication speed of the communication is 4 Mbps, the load applied to the wireless access point device 12A is equivalent to 4 Mbps. Under such circumstances, when the wireless terminal 11B further starts communication at 2 Mbps via the wireless access point device 12A, the load on the wireless access point device 12A becomes an amount equivalent to 6 Mbps. On the other hand, since the wireless access point device 12B remains in the no-load state, a large difference occurs in the load applied between the wireless access point devices 12A and 12B (hereinafter, such a state is referred to as “ The load is uneven. "
[0006]
In order to prevent the load imposed on each wireless access point device from being biased in this way, the wireless terminal 11B switches the connection destination to the wireless access point device 12B in a no-load state, and switches the wireless access point device 12B. Initiate communication via As a result, the load on the wireless access point device 12A is equivalent to 4 Mbps, and the load on the wireless access point device 12B is equivalent to 2 Mbps. In the wireless communication system shown in FIG. 15, the load is thus distributed among the plurality of wireless access point devices.
[0007]
The load balancing technique described above is suitable for a communication mode in which a receiver and a sender perform one-to-one communication (hereinafter, such a communication mode is referred to as “unicast”). However, in the existing communication mode, there is a communication mode in which a plurality of recipients receive data transmitted from a sender (hereinafter, such a communication mode is referred to as “multicast”) in addition to unicast. . As an example of the multicast, an IP multicast realized according to IP (Internet Protocol) which is a communication protocol of a network layer is widely known. In IP multicast, a multicast group is configured by assigning a multicast IP address (hereinafter, such an IP address is referred to as a “multicast address”) to a group of recipients who want to receive the same data. Note that the multicast address assigned to the multicast group is unique to the group. A client desiring to receive data transmitted to a certain multicast group must first have a client desiring to receive the data in a network device (eg, a router or the like) that manages the network to which the client belongs. Is transmitted, and this information is stored. In the following, transmitting and storing such information to the network device is referred to as "joining a multicast group". After such participation is made, when data addressed to the multicast address is routed from the backbone network according to the IP protocol, the network device joins the data to the multicast group under its own device. Copy as many clients as there are and send to each client. Note that actual data transmission / reception is performed as transmission / reception of a packet, which is a data block obtained by dividing the data by a predetermined data size. Therefore, the data is also copied in packet units.
[0008]
The multicast described above can be executed in the wireless communication system described above, and when transmitting the same packet to a plurality of wireless terminals, the communication band of the wireless section is effectively used by using the multicast. can do. The reason is that, in a wireless section, since a radio signal transmitted from a wireless access point device can be received by all wireless terminals connected to the wireless access point device, individual wireless terminals participating in a multicast group This is because it is not necessary to copy and transmit the packet every time.
[0009]
Next, in the wireless communication system of FIG. 15, the wireless terminal 11B joins the same multicast group under a situation where the wireless terminal 11A is already connected to the wireless access point device 12A and receives a packet addressed to a certain multicast group. Let's consider the case. Since the wireless access point device 12A transmits a packet to the multicast group, a large load is applied as compared to the wireless access point device 12B. As described above, in such a situation, the wireless terminal 11B connects to the wireless access point device 12B and joins the multicast group. Therefore, packets are transmitted from both the wireless access point devices 12A and 12B to the same multicast group. That is, in the wireless section, the communication band used for transmitting packets addressed to this multicast group is doubled. Further, assuming that a load corresponding to 4 Mbps is applied to the wireless access point device by transmitting a packet addressed to the multicast group, a load corresponding to 4 Mbps is applied to both the wireless access point devices 12A and 12B. Become. Under such circumstances, even if the wireless terminal 11C attempts to perform unicast, a large load (a load corresponding to 4 Mbps) is applied to the wireless access point devices 12A and 12B. Regardless of the connection to either 12A or 12B to start communication, it may be difficult to perform communication with desired communication quality. As a technique for solving such a problem, there is a technique disclosed in Non-Patent Document 1. Hereinafter, the technology disclosed in Non-Patent Document 1 will be described with reference to the drawings.
[0010]
FIG. 16 is a diagram illustrating an example of a wireless communication system that performs load distribution according to Non-Patent Document 1. The wireless communication system shown in FIG. 16 differs from the wireless communication system shown in FIG. 15 in that wireless terminals 21A, 21B, 21C, and 21D are provided instead of wireless terminals 11A, 11B, 11C, and 11D. The management node device 22 is newly provided. In the following, when it is not necessary to distinguish each of the wireless terminals 21A, 21B, 21C and 21D, it is described as "wireless terminal 21".
[0011]
The management node device 22 is a computer device that communicates with the network switch 13 via a communication line, and stores the correspondence information shown in FIG. As shown in FIG. 17, the correspondence information includes an access point identifier, a group identifier, and the number of receiving terminals. The access point identifier is an identifier (for example, an IP address assigned to the wireless access point device) that uniquely identifies the wireless access point device included in the wireless communication system shown in FIG. In the following, the IP address assigned to the wireless access point device 12A is “10.1.1.2”, and the IP address assigned to the wireless access point device 12B is “10.1.1. 3 ". The group identifier is an identifier (for example, a multicast address) that uniquely identifies a multicast group to which a packet is transmitted from the wireless access point device identified by the access point identifier associated with the group identifier. In the following, it is assumed that a multicast address “234.4.1.2.3” is assigned to the multicast group 1 and data is transmitted to the multicast address at a communication speed of 6 Mbps. On the other hand, the multicast group 2 is assigned a multicast address “234.4.1.4”, and it is assumed that data is transmitted to this multicast address at a communication speed of 4 Mbps. Then, the number of receiving terminals refers to the multicast specified by the group identifier associated with the number of receiving terminals connected to the wireless access point device identified by the access point identifier associated with the number of receiving terminals. This is information indicating the number of wireless terminals participating in the group. The management node device 22 has a function of notifying the wireless terminal 21 of a wireless access point device that is transmitting a packet to a multicast group that the user of the wireless terminal 21 desires to join. More specifically, when the management node device 22 receives a notification from the wireless terminal 21 to inquire about a wireless access point device that is transmitting a packet to a certain multicast group, the management node device 22 An access point identifier of the access point device is specified, and the access point identifier is transmitted to the transmission source of the notification.
[0012]
On the other hand, when the user is instructed to join a certain multicast group, the wireless terminal 21 determines whether or not there is a wireless access point device 12 transmitting a packet addressed to the multicast group. Inquires the device 22. Then, when the management node device 22 notifies that the corresponding wireless access point device exists, the wireless terminal 21 switches the connection to the wireless access point device and joins the multicast group. For example, when the wireless terminal 21B joins the multicast group 1 under the situation where the wireless terminal 21A connects to the wireless access point device 12A and joins the multicast group 1, the wireless terminal 21B connects to the wireless access point device 12A. Join multicast group 1. For this reason, packets addressed to the same multicast group are prevented from being transmitted from a plurality of wireless access point devices, and communication bandwidth in a wireless section is prevented from being wasted.
[0013]
However, in the wireless communication system shown in FIG. 16, when the wireless terminal 21B joins the multicast group at almost the same time as the wireless terminal 21A joins the multicast group, different wireless access point devices join the same multicast group. It is possible that a packet is transmitted to the destination. The reason is that before the wireless terminal 21A joins the multicast group, the wireless terminal 21B requests the transmission of the corresponding information before updating the corresponding information, and the corresponding information that does not reflect the update is transmitted. Is transmitted to the wireless terminal 21B. Non-Patent Document 1 also discloses a technique for avoiding such a situation. Specifically, the management node device 22 assigns a priority to each wireless access point device based on the number of wireless terminals connected to the wireless access point device and participating in the multicast group, and periodically assigns the priority. To the wireless terminal 21. Then, the wireless terminal 21 receiving such a notification switches the connection destination to the wireless access point device having the highest priority when the priority of the connected wireless access point device is low. This prevents packets addressed to the same multicast group from being transmitted from a plurality of wireless access point devices, and prevents a communication band in a wireless section from being wasted.
[0014]
[Non-patent document 1]
IEICE Technical Report,
NS2002-115, IN2002-59, CS2002-70,
September 2002,
“Multicast receiver aggregation at wireless LAN hotspots
Proposal of method ”,
Yuki Moriya, Yukio Atsumi
[0015]
[Problems to be solved by the invention]
According to the technology disclosed in Non-Patent Document 1, each of the wireless terminals participating in the same multicast group is prevented from connecting to a different wireless access point device, and the communication band in the wireless section is prevented from being wasted. You. However, on the other hand, in the wireless communication system illustrated in FIG. 16, a load imbalance may occur between the wireless access point devices 12A and 12B. As an example, in the wireless communication system shown in FIG. 16, the wireless terminal 21B joins the multicast group 2 at almost the same time as the wireless terminal 21A joins the multicast group 1, and after a while, the wireless terminal 21C joins the multicast group. 1 and the wireless terminal 21 </ b> D joins the multicast group 2.
[0016]
At the time when the wireless terminals 21A and 21B join the multicast group, none of the wireless access point devices 12A and 12B has transmitted a packet addressed to the multicast group, and the corresponding information indicating that fact is transmitted to the management node device 22. Is stored in Since both the wireless access point devices 12A and 12B are in a no-load state, the wireless terminals 21A and 21B connect to the wireless access point device 12A based on only the communication quality with the wireless access point device, and each of the multicast groups Start receiving packets addressed to it. After that, when the wireless terminals 21C and 21D join the multicast group, the correspondence information indicating that the wireless access point device 12A is transmitting packets addressed to the multicast groups 1 and 2 is stored in the management node device 22. I have. Therefore, the wireless terminals 21C and 21D connect to the wireless access point device 12A based on the correspondence information acquired from the management node device 22, and start receiving packets addressed to the multicast group. As a result, the applied loads are biased between the wireless access point devices 12A and 12B.
[0017]
When the wireless terminals 21A, 21B, 21C, and 21D join the multicast group 1 in this order, according to the technology disclosed in Non-Patent Document 1, the wireless terminals 21B, 21C, and 21D are also connected to the wireless terminal 21A. Connected to the wireless access point device and join the multicast group. In this state, when the wireless terminal 21A stops receiving the packet addressed to the multicast group 1 and newly joins the multicast group 2, the wireless terminal 21A is already connected to the wireless access point device 12A. The user joins the multicast group 2 while being connected to the device 12A. Therefore, while the wireless access point device 12B is in a no-load state, packets addressed to the multicast groups 1 and 2 are transmitted from the wireless access point device 12A, and the load concentrates on the wireless access point device 12A. Needless to say, the above problem cannot be solved by using the load distribution technology for unicast described above. For example, when the wireless terminals 21A, 21B, 21C, and 21D specify a connection destination and join the multicast group 1 in this order based on the conventional load distribution technology, two of these four wireless terminals It connects to the wireless access point device 12B. As a result, the packets addressed to the multicast group 1 are transmitted from both the wireless access point devices 12A and 12B, and the communication band in the wireless section is wasted.
[0018]
In other words, even if the technology disclosed in Non-Patent Document 1 or the load distribution technology for unicast is used, in the following two cases, it is possible to prevent the communication band in the wireless section from being wasted. However, the load on the wireless access point device cannot be distributed. First, there is a case where a plurality of wireless terminals try to join different multicast groups substantially simultaneously. Second, there is a case where a wireless terminal that has joined a certain multicast group leaves the multicast group and joins another multicast group.
[0019]
The present invention has been made in view of the above problems, and a case where each of a plurality of wireless terminals substantially simultaneously attempts to join a different multicast group or a wireless terminal that has already joined an existing multicast group Even when leaving the multicast group and joining another multicast group, load is distributed among a plurality of wireless access point devices while avoiding wasteful use of communication bandwidth in a wireless section. It aims to provide technology.
[0020]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a storage unit, load information indicating a load on a wireless access point device transmitting a data block to one or a plurality of multicast groups, and the multicast group. A writing unit that acquires an identifier to be identified for each wireless access point device and writes the identifier into the storage unit; and, based on the storage content of the storage unit, whether there is a bias in the load applied to each of the wireless access point devices. Determining means for determining whether or not the load applied to each of the wireless access point devices is biased, when the determination means determines that there is a bias, the data block is loaded from the wireless access point device with the largest applied load. At least one of the multicast groups being transmitted Requesting means for requesting the wireless terminals participating in the multicast group specified by the specifying means to switch the connection to the wireless access point device with the smallest load. A management node device having the same.
[0021]
Further, in order to solve the above problem, the present invention provides a wireless access point device that transmits a data block addressed to one or more multicast groups, load information indicating a load applied to the wireless access point device, and A management node device for acquiring and storing, for each wireless access point device, an identifier for uniquely identifying a multicast group to which a data block is transmitted from the wireless access point device, wherein the management node device It is determined whether or not there is a bias in the load applied to each of the wireless access point devices based on the, and if it is determined that there is a bias, the data block is transmitted from the wireless access point device with the largest load. At least one of the multicast groups sending A wireless communication system comprising: specifying a multicast group of a plurality of mobile terminals; and requesting a wireless terminal participating in the specified multicast group to switch a connection to a wireless access point device with the smallest load. provide.
[0022]
According to another aspect of the present invention, a management node device that communicates with a wireless access point device that transmits a data block addressed to one or more multicast groups has a load imposed on the wireless access point device. A first step of obtaining, for each wireless access point device, load information representing the following, and an identifier for uniquely identifying a multicast group to which a data block is transmitted from the wireless access point device; and A second step of detecting, based on the load information obtained in step 1, that the loads applied to each of the wireless access point devices are biased, and wherein the load applied by the management node device is Multi-block transmitting data block from largest wireless access point device A third step of specifying at least one multicast group from the multicast groups, and the management node device is operating on a wireless terminal participating in the multicast group specified in the third step And a fourth step of requesting that the connection destination be switched to the wireless access point device with the smallest load.
[0023]
In order to solve the above-mentioned problem, the present invention provides a computer device with load information indicating a load applied to a wireless access point device transmitting a data block to one or a plurality of multicast groups, and the multicast group. A storage function of acquiring and storing an identifier for uniquely identifying the wireless access point device for each wireless access point device, and a load applied to each of the wireless access point devices based on the load information stored by the storage function. And a determining function of determining whether or not the load applied to each of the wireless access point devices is biased when the determining function determines that the load is biased. At least one of the multicast groups being sent blocks A specific function of specifying a multicast group, and a request function of requesting a wireless terminal participating in the multicast group specified by the specific function to switch connection to a wireless access point device with the smallest load. And a recording medium readable by a computer device, the recording medium recording the program.
[0024]
According to the management node device, the wireless communication system, the load distribution method, the program, and the recording medium, when the loads applied to the wireless access point devices are uneven, the wireless access having the largest applied load At least one multicast group is specified from the multicast groups to which the data blocks are transmitted from the point device, and a connection is made to the wireless access point device with the least load applied to the wireless terminals participating in the multicast group. Switching is required.
[0025]
According to another aspect of the present invention, there is provided a wireless access point device that transmits a data block to a wireless section, a connection unit that connects to a wireless access point device, load information indicating a load applied to the wireless access point device, and the wireless access point device. Reception for receiving, via a wireless access point device connected by the connection means, correspondence information in which an identifier uniquely identifying a destination to which a data block is transmitted from the point device is written for each wireless access point device. Means, input means for inputting a user's instruction, and, when the instruction input by the input means is an instruction indicating that the user should join a certain multicast group, transmitting a data block addressed to the multicast group. Whether or not there is a wireless access point device Determining means for determining based on the corresponding information, and when the determining means determines that there is a corresponding wireless access point device, switching the connection to the wireless access point device, and conversely, the corresponding wireless access point device When the determination unit determines that there is no device, a wireless terminal having a control unit that controls the connection unit so as to switch the connection to a wireless access point device with the smallest load is provided.
[0026]
In order to solve the above-mentioned problems, the present invention provides a computer device with a connection function for connecting to a wireless access point device that transmits a data block to a wireless section, and load information indicating a load applied to the wireless access point device. And an identifier for uniquely identifying a destination to which a data block is transmitted from the wireless access point device, and correspondence information written for each wireless access point device through the wireless access point device connected by the connection function. A receiving function for receiving a user's instruction, an input function for inputting a user's instruction, and, when the instruction input by the input function is an instruction indicating that the user should join a certain multicast group, the data addressed to the multicast group. Determining whether there is a wireless access point device transmitting the block A determination function that determines based on the correspondence information received by the communication function, and when the determination function determines that there is a corresponding wireless access point device, switches the connection to the wireless access point device, and conversely, A program for realizing a control function for controlling the connection function so as to switch the connection to a wireless access point device with the smallest load when the determination function determines that there is no corresponding wireless access point device; And a computer-readable recording medium that records the program.
[0027]
According to such a wireless terminal, a program, and a recording medium, a wireless terminal instructed by a user to join a certain multicast group has a wireless access point device transmitting a data block to the multicast group. In this case, the connection is switched to the wireless access point device. Conversely, if there is no corresponding wireless access point device, the connection is switched to the wireless access point device with the smallest load.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
[0029]
(1: System configuration)
FIG. 1 is a diagram showing an example of an overall configuration of a wireless communication system including a management node device and a wireless terminal according to the present invention. The wireless communication system shown in this figure differs from the wireless communication system shown in FIG. 16 in that wireless terminals 31A, 31B, 31C and 31D are provided instead of wireless terminals 21A, 21B, 21C and 21D, and the management node device 22 in that a management node device 32 is provided. In the following, when it is not necessary to distinguish each of the wireless terminals 31A, 31B, 31C and 31D, it is described as "wireless terminal 31".
[0030]
The management node device 32 stores the correspondence information shown in FIG. 2 instead of the correspondence information shown in FIG. As shown in FIG. 2, the point that the correspondence information stored in the management node device 32 includes load information indicating the load applied to the wireless access point device 12 is stored in the management node device 22. Is different from the corresponding information. In the present embodiment, as an example of the load information, a value expressing the ratio of the data amount actually processed to the maximum data amount that can be processed by the wireless access point device per unit time is expressed in percentage. The management node device 32 transmits the correspondence information to the wireless terminal 31 in response to a request from the wireless terminal 31. On the other hand, when there is an uneven load on the wireless access point device under the management node device 32, In order to correct the bias, the wireless terminal 31 is requested to switch the wireless access point device of the connection destination.
[0031]
The wireless terminal 31 is a computer device having a function of connecting to the wireless access point device 12A or 12B and performing wireless communication. In addition, the wireless terminal 31 has a function of acquiring the correspondence information from the management node device 32 and switching the connection to the wireless access point device specified based on the acquired correspondence information. Further, the wireless terminal 31 has a function of switching a wireless access point device to be connected to in response to a request from the management node device 32.
[0032]
In the wireless communication system shown in FIG. 1, the wireless terminal 31 switches the wireless access point device of the connection destination in response to a request from the management node device 32, or the wireless terminal 31 based on the correspondence information acquired from the management node device 32. By switching the connection destination wireless access point device to 31, the load is distributed between the wireless access point devices 12 </ b> A and 12 </ b> B while avoiding useless use of the communication band in the wireless section.
[0033]
(2: Configuration of wireless terminal 31)
Next, the configuration of the wireless terminal 31 will be described with reference to FIG. FIG. 3 is a block diagram illustrating an example of a hardware configuration of the wireless terminal 31. As illustrated in FIG. 3, the wireless terminal 31 includes a control unit 41, an operation unit 42, a wireless communication unit 43, and a storage unit. 44, and a bus 46 for mediating data transfer between these components. The control unit 41 is, for example, a CPU (Central Processing Unit), and controls each unit of the wireless terminal 31. The operation unit 42 includes operation elements (numerical keys, cursor keys, and the like) for allowing the user to input various instructions, and transfers data according to the operation contents of the operation elements to the control unit 41.
[0034]
The wireless communication unit 43 is for performing wireless communication with the wireless access point device 12. The wireless communication unit 43 transfers data transmitted from the wireless access point device 12 to the control unit 41 and wirelessly transfers data transferred from the control unit 41. It transmits to the access point device 12.
[0035]
The storage unit 44 includes a volatile storage unit 441 and a nonvolatile storage unit 442. The volatile storage unit 441 is, for example, a RAM (Random Access Memory), and is used as a work area by the control unit 41 that is executing software. The nonvolatile storage unit 442 is, for example, an EEPROM (Electrically Erasable Programmable Read Only Memory), and stores various software. Examples of the software stored in the nonvolatile storage unit 442 include OS software for causing the control unit 41 to implement an operating system (hereinafter, referred to as “OS”), and software via the wireless access point device 12. Communication software for causing the control unit 41 to realize a function of transmitting and receiving data by cast or multicast is exemplified. Hereinafter, functions provided to the control unit 41 by executing these software will be described.
[0036]
When a power supply (not shown) is turned on, for example, by pressing a power button (not shown) provided on the operation unit 42, the control unit 41 first stores the OS software in the nonvolatile storage unit 442. And execute it. The control unit 41 operating in accordance with the OS software is provided with a function of controlling each unit of the wireless terminal 31 and a function of reading and executing other software from the nonvolatile storage unit 442. When instructed to join a certain multicast group while operating according to the OS software, the control unit 41 reads out the communication software from the nonvolatile storage unit 442 and executes it. The control unit 41 operating in accordance with the communication software is provided with the following two functions.
[0037]
The first function is a function of switching the connection destination wireless access point device based on a request from the management node device 32. The second function is to acquire correspondence information from the management node device 32, switch the connection to a wireless access point device determined based on the acquired correspondence information, and join the multicast group via the wireless access point device. Function. More specifically, the control unit 41 first transmits a communication message (hereinafter, referred to as a “correspondence information transmission request”) requesting transmission of the correspondence information to the management node device 32, and the management node device 32 The connection is switched to the wireless access point device determined based on the correspondence information transmitted from. Next, the control unit 41 transmits a communication message (hereinafter, referred to as “participation notification”) notifying that it is joining the multicast group via the wireless access point device to both the router 14 and the management node device 32. . When the user is instructed to leave the multicast group, the control unit 41 sends a communication message (hereinafter referred to as “leave notification”) to that effect to both the router 14 and the management node device 32. Send. The notification of participation and the notification of leaving include the access point identifier of the wireless access point device and the group identifier of the multicast group. Although a detailed description is omitted, when a user instructs to perform unicast communication, the control unit 41 operating according to the communication software is connected to a connection destination based on a conventional load distribution technique. Of course, the wireless access point device may be determined.
[0038]
As described above, the hardware configuration of the wireless terminal 31 is the same as that of a general computer device, and the present invention is implemented by causing the control unit 41 to execute various software stored in the nonvolatile storage unit 442. The function unique to the wireless terminal according to the above is realized.
[0039]
(3: Configuration of Management Node Device 32)
Next, the configuration of the management node device 32 will be described with reference to FIG. As shown in FIG. 4, the hardware configuration of the management node device 32 is different from the hardware configuration of the wireless terminal 31 in that a wired communication unit 45 is provided in place of the wireless communication unit 43 and A nonvolatile storage unit 443 is provided in place of the storage unit 442. The wired communication unit 45 is connected to the network switch 13 via a communication line, and communicates with the network switch 13. The wired communication unit 45 receives the data transmitted from the network switch 13 through the communication line, transfers the received data to the control unit 41, and transmits the data transferred from the control unit 41 to the communication line. Via the network switch 13. The nonvolatile storage unit 443 is, for example, a hard disk, and stores a threshold value used when determining whether or not the loads applied to the wireless access point devices 12A and 12B are biased. The non-volatile storage unit 443 stores OS software and load management software for causing the control unit 41 to implement a load management function described later. Hereinafter, functions provided to the control unit 41 of the management node device 32 by executing the software will be described.
[0040]
When a power supply (not shown) is turned on, for example, by pressing a power button (not shown) provided on the operation unit 42, the control unit 41 first reads the OS software from the nonvolatile storage unit 443. Execute. The control unit 41 operating in accordance with the OS software is provided with a function of controlling each unit of the wireless terminal 31 and a function of reading and executing other software from the nonvolatile storage unit 443. Then, the control unit 41 in a state where the execution of the OS software is completed and the OS is realized immediately reads out and executes the load management software from the nonvolatile storage unit 443. The control unit 41 operating according to the load management software is provided with three functions characteristic of the management node device according to the present invention.
[0041]
The first function is to write the correspondence information (see FIG. 2) into the volatile storage unit 441 according to the content of the communication message transmitted from the wireless terminal 31 or to transmit the correspondence information to the wireless terminal 31. Function. More specifically, when the communication message transmitted from the wireless terminal 31 is a participation notification, the control unit 41 transmits the access point identifier and the correspondence information corresponding to the group identifier included in the participation notification. Add 1 to the number of receiving terminals. If the corresponding correspondence information is not stored in the volatile storage unit 441, the control unit 41 newly stores the access point identifier, the group identifier, and the correspondence information including 1 as the number of receiving terminals in the volatile storage unit 441. Writing to the storage unit 441. When the communication message transmitted from the wireless terminal 31 is a correspondence information transmission request, the control unit 41 of the management node device 32 reads out the correspondence information from the volatile storage unit 441, and performs a communication including the correspondence information. A message (hereinafter, referred to as “corresponding information transmission response”) is transmitted to the wireless terminal 31. Further, when the communication message transmitted from the wireless terminal 31 is an exit notification, the control unit 41 determines whether the receiving terminal has received the corresponding information corresponding to the access point identifier and the group identifier included in the exit notification. Subtract 1 from the number. When the number of receiving terminals becomes 0, the control unit 41 deletes the corresponding information from the volatile storage unit 441. The writing destination of the correspondence information is not limited to the volatile storage unit 441, but may be the nonvolatile storage unit 443.
[0042]
The second function is a function of acquiring load information from the wireless access point devices 12A and 12B and updating the correspondence information based on the acquired load information. More specifically, the control unit 41 performs communication, for example, on a regular basis with the wireless access point device 12 based on SNMP (Simple Network Management Protocol) or the like, and a load representing the load applied to the wireless access point device 12. The information is acquired, and the corresponding information corresponding to the wireless access point device is updated with the acquired load information. Note that the communication performed by the control unit 41 with the wireless access point device 12 when acquiring the load information is not limited to communication conforming to SNMP. In short, any mode may be used as long as load information indicating the load on the wireless access point device 12 can be obtained. Further, in the present embodiment, a case will be described in which the control unit 41 periodically acquires the load information. However, an aspect in which the load information is acquired in response to receiving various notifications transmitted from the wireless terminal 31 is described. Of course.
[0043]
The third function is a function of periodically determining whether or not the load applied to each wireless access point device is biased, and correcting the bias when it is determined that the load is biased. More specifically, the control unit 41 determines whether the magnitude of the difference between the maximum value and the minimum value of the load applied to each wireless access point device is larger than a threshold stored in the volatile storage unit 441. If the difference is greater than the threshold, it is determined that the loads on the wireless access point devices are biased. In the present embodiment, a case where 50 is set as the threshold value will be described. However, the value is not limited to 50, and may be any value appropriately determined according to the management policy. Good. Then, when the control unit 41 determines that the loads applied to the respective wireless access point devices are biased, the controller 41 corrects the bias as described below. That is, among the multicast groups receiving packets via the wireless access point device loaded with the load corresponding to the maximum value, the control unit 41 selects the wireless access point loaded with the load corresponding to the minimum value. Identify a multicast group that should receive packets via the device. Then, the control unit 41 requests the wireless terminal 31 participating in the multicast group to switch the connection to the wireless access point device having a load corresponding to the minimum value.
[0044]
As described above, the hardware configuration of the management node device 32 is the same as that of a general computer device, and by causing the control unit 41 to execute various software stored in the nonvolatile storage unit 443, A function unique to the management node device according to the invention is realized.
[0045]
(4: Operation)
Next, among operations performed by the management node device and the wireless terminal according to the present embodiment, an operation that remarkably shows the feature will be described with reference to the drawings.
[0046]
(4-1: Operation example 1)
First, in the wireless communication system shown in FIG. 1, it is assumed that the wireless terminals 31A and 31B are connected to the wireless access point device 12A, and the wireless terminals 31C and 31D are connected to the wireless access point device 12B. Then, it is assumed that none of the wireless terminals 31A, 31B, 31C and 31D have joined the multicast group. A case where the wireless terminal 31A joins the multicast group 1 and the wireless terminal 31B joins the multicast group 2 almost simultaneously from this state will be described with reference to a sequence diagram shown in FIG. At the start of the operation described below, it is assumed that none of the wireless access point apparatuses 12A and 12B transmit packets to the multicast groups 1 and 2, and both are in a no-load state. . For this reason, the correspondence information shown in FIG. 6 is stored in the volatile storage unit 441 of the management node device 32.
[0047]
When instructed to join the multicast group via the operation unit 42, the control unit 41 of the wireless terminal 31 transmits the above-described correspondence information transmission request to the management node device 32 via the wireless communication unit 43. In this operation example, as shown in FIG. 5, almost simultaneously with the control unit 41 of the wireless terminal 31A transmitting the correspondence information transmission request 71A to the management node device 32, the control unit 41 of the wireless terminal 31B also transmits the correspondence information. The transmission request 71B is transmitted to the management node device 32. In the following, when there is no need to distinguish between the correspondence information transmission requests 71A and 71B, they are described as "correspondence information transmission requests 71". In the present embodiment, the case has been described where the wireless terminal 31 transmits the correspondence information transmission request to the management node device 32 by unicast, but the transmission mode of the correspondence information transmission request is not limited to unicast. Instead, it may be multicast or broadcast transmission. By doing so, even when the wireless terminal 31 cannot detect the communication address assigned to the management node device 32, the above-mentioned correspondence information transmission request can be transmitted.
[0048]
The correspondence information transmission request 71 reaches the management node device 32 via the wireless access point device 12A and the network switch 13 in this order. When receiving the correspondence information transmission request 71 via the wired communication unit 45, the control unit 41 of the management node device 32 reads the correspondence information from the volatile storage unit 441, and sends a correspondence information transmission response including the correspondence information to the wired connection unit. The corresponding information transmission request 71 is transmitted to the transmission source via the communication unit 45. In this operation example, as shown in FIG. 5, the control unit 41 of the management node device 32 transmits a correspondence information transmission response 72A addressed to the wireless terminal 31A, and transmits a correspondence information transmission response 72B addressed to the wireless terminal 31B. In the following, when there is no need to distinguish between the correspondence information transmission responses 72A and 72B, the correspondence information transmission responses 72A and 72B are described as “correspondence information transmission responses 72”. In the present embodiment, a case has been described in which the management node device 32 transmits the correspondence information transmission response to the wireless terminal 31 by unicast. However, the transmission mode of the correspondence information transmission response is not limited to unicast. Instead, it may be multicast or broadcast transmission.
[0049]
The correspondence information transmission response 72 reaches the destination wireless terminal via the network switch 13 and the wireless access point device 12A in this order. Specifically, the correspondence information transmission response 72A reaches the wireless terminal 31A, and the correspondence information transmission response 72B reaches the wireless terminal 31B. An operation performed by the control unit 41 of the wireless terminal 31 when the correspondence information transmission response 72 is received will be described with reference to a flowchart shown in FIG.
[0050]
As shown in FIG. 7, when receiving the correspondence information transmission response 72 via the wireless communication unit 43, the control unit 41 of the wireless terminal 31A or 31B analyzes the correspondence information transmission response 72, and The correspondence information included in the information 72 is acquired (step SA1).
[0051]
Next, the control unit 41 determines whether or not there is a wireless access point device transmitting a packet to the multicast group instructed by the user to join, based on the correspondence information acquired in step SA1. (Step SA2). Specifically, when the correspondence information acquired in step SA1 includes an access point identifier associated with the group identifier of the multicast group, the control unit 41 sets the corresponding wireless access point device to It is determined that there is. Conversely, when the access point identifier associated with the group identifier is not included, the control unit 41 determines that there is no corresponding wireless access point device.
[0052]
If the determination result in step SA2 is “Yes”, the control unit 41 connects to the wireless access point device specified by the access point identifier associated with the group identifier (step SA3). Conversely, if the determination result in step SA2 is “No”, the control unit 41 refers to the load information included in the correspondence information acquired in step SA1, and determines that the Connect to the access point device (step SA4). In this operation example, the correspondence information shown in FIG. 6 is transmitted from the management node device 32. Therefore, the result of the determination in step SA3 is “No”, and the control unit 41 performs the processing in step SA4. As shown in FIG. 6, since both wireless access point devices 12A and 12B are in a no-load state, control unit 41 does not switch the connection destination from the currently connected wireless access point device 12A.
[0053]
Then, the control unit 41 joins the multicast group via the wireless access point device connected in step SA3 or SA4. Specifically, the control unit 41 transmits a participation notification to the effect that it joins the multicast group to the router 14 via the wireless access point device connected in step SA3 or SA4. Hereinafter, the router 14, the network switch 13, the wireless access point device 12, and the wireless terminal 31 perform the same operation as general multicast. Specifically, the router 14 notifies the backbone network that there are clients (wireless terminals 31A and 31B) participating in the multicast group under its own device. When the router 14 receives a packet transmitted from the backbone network to the multicast group, the router 14 transmits the packet to the subordinate network switch 13. The network switch 13 refers to the contents of the participation notification transmitted from the wireless terminals 31A and 31B to the router 14, and detects that there are wireless terminals participating in the multicast groups 1 and 2 under the wireless access point device 12A. I do. Then, when receiving the packets addressed to the multicast groups 1 and 2 from the router 14, the network switch 13 transmits the packets only to the communication port connecting the wireless access point device 12A. The wireless access point device 12A receives a packet addressed to the multicast group transmitted from the network switch 13, and sends the received packet to a wireless section. When the control unit 41 of the wireless terminal 31A or 31B receives the packet addressed to the multicast group transmitted to the wireless section in this manner, the control unit 41 transmits the above-described participation notification 73 to the management node to notify that the reception of the packet has started. The message is transmitted to the device 32 (step SA5).
[0054]
On the other hand, upon receiving the participation notification 73 via the wired communication unit 45, the control unit 41 of the management node device 32 generates correspondence information including the access point identifier and the group identifier included in the participation notification 73, and The number of receiving terminals is set to 1 and written to the volatile storage unit 441. With the above operation, the wireless terminals 31A and 31B receive the packet addressed to the multicast group via the wireless access point device 12A, and the correspondence information stored in the volatile storage unit 441 of the management node device 32 is as shown in FIG. The state shown in FIG.
[0055]
Next, a case where the wireless terminal 31C joins the multicast group 1 under the situation indicated by the correspondence information in FIG. 8 will be described.
[0056]
When the user instructs to join the multicast group 1, the control unit 41 of the wireless terminal 31C performs the processing of steps SA1 and SA2 described above, which is the same as the control unit 41 of the wireless terminal 31A or 31B. is there. However, as shown in FIG. 8, the correspondence information received by the wireless terminal 31C from the management node device 32 is that the packet is transmitted from the wireless access point device 12A to the multicast group instructed by the user to join. Is shown. Therefore, the result of the determination in step SA2 described above is “Yes”, and the control unit 41 of the wireless terminal 31C performs the processing in step SA3 described above. That is, the control unit 41 of the wireless terminal 31C switches the connection destination to the wireless access point device 12A. Thereafter, the control unit 41 of the wireless terminal 31C joins the multicast group 1 via the wireless access point device 12A, and upon receiving a packet addressed to the multicast group 1, transmits the join notification to the management node device 32. The control unit 41 of the management node device 32 that has received the participation notification updates the correspondence information stored in the volatile storage unit 441 based on the content of the participation notification. Specifically, the control unit 41 of the management node device 32 adds 1 to the number of receiving terminals of the correspondence information including the access point identifier of the wireless access point device 12A and the multicast address of the multicast group 1. Further, after that, the control unit 41 acquires load information indicating the load applied to each wireless access point device, and updates the correspondence information with the acquired load information, so that the volatile storage unit 441 of the management node device 32 The stored correspondence information is in the state shown in FIG.
[0057]
When the operation described above is completed, as shown in FIG. 9, the load on the wireless access point device 12A is significantly larger than the load on the wireless access point device 12B. . That is, the loads applied to the wireless access point devices are biased. Hereinafter, an operation performed by the management node device 32 to correct the bias will be described with reference to a flowchart illustrated in FIG.
[0058]
FIG. 10 is a flowchart illustrating the flow of the bias correction operation performed by the control unit 41 of the management node device 32. As shown in FIG. 10, the control unit 41 of the management node device 32 first obtains load information from each of the wireless access point devices 12A and 12B according to a predetermined algorithm such as SNMP, and The correspondence information is updated based on the information (step SB1).
[0059]
Next, the control unit 41 of the management node device 32, based on the correspondence information stored in the volatile storage unit 441, applies the maximum load to the wireless access point device (hereinafter, referred to as “reduction target device”). (Hereinafter referred to as “increase target device”) with the smallest load (step SB2). In this operation example, as shown in FIG. 9, the wireless access point device 12A is loaded with 100% of its processing capacity, and the wireless access point device 12B is in a no-load state. Therefore, the control unit 41 of the management node device 32 specifies the wireless access point device 12A as the reduction target device and specifies the wireless access point device 12B as the increase target device.
[0060]
Next, the control unit 41 of the management node device 32 determines whether or not the difference between the load applied to the reduction target device and the load applied to the increase target device is larger than a predetermined threshold. (Step SB3). In the present embodiment, the case where the difference between the load applied to the reduction target device and the load applied to the increase target device is simply compared with the above-described predetermined threshold has been described. This comparison process may be performed only when the load exceeds a certain threshold.
[0061]
When the determination result of step SB3 is “No”, the control unit 41 ends the bias correction operation. Conversely, if the determination result in step SB3 is “Yes”, the control unit 41 determines, among the multicast groups to which packets are being transmitted from the reduction target device, the multicast groups to which packets are to be transmitted from the increase target device. Is specified (step SB4). In the present embodiment, the control unit 41 specifies, as a target multicast group, a multicast group having the smallest number of receiving terminals among the multicast groups to which packets are transmitted from the reduction target device. In this operation example, as shown in FIG. 9, the load on the reduction target device (that is, the wireless access point device 12A) is 100, and the increase target device (that is, the wireless access point device 12B) is unloaded. Since it is in the state, the determination result in step SB3 described above is “Yes”. Therefore, the above-described processing of step SB4 is performed. In Step SB4, since two wireless terminals have joined the multicast group 1 and one wireless terminal has joined the multicast group 2, the multicast group 2 is specified as the target multicast group. When there are a plurality of multicast groups having the minimum number of receiving terminals, the target multicast group may be randomly selected from the multicast groups. In short, any method may be used as long as one target multicast group is specified from among the multicast groups having the minimum number of receiving terminals. In this embodiment, a case has been described in which the multicast group having the minimum number of receiving terminals is specified as the target multicast group. This is because such an effect is obtained that the number of wireless terminals for switching the wireless access point device can be reduced. However, it goes without saying that the target multicast group may be specified regardless of the number of receiving terminals. Further, in the present embodiment, one multicast group is specified from among the multicast groups to which the data blocks are transmitted via the wireless access point device having the largest load, and participates in this multicast group. The case where the wireless terminal 31 switches the connection destination has been described. However, a plurality of multicast groups are specified from among the multicast groups whose data blocks are transmitted via the wireless access point device having the largest load, and the wireless terminals 31 participating in those multicast groups are identified. It goes without saying that the connection destination may be switched.
[0062]
Then, in step SB5 subsequent to step SB4, the control unit 41 increases the connection destination to the wireless terminal participating in the target multicast group identified in step SB4 (ie, the wireless access point device 12B). ) Is transmitted, and the bias correction operation ends. As a mode of transmitting the above notification to the wireless terminal participating in the target multicast group, the notification may be transmitted to a multicast address of the multicast group. It may be transmitted to all the wireless terminals that are performing the transmission (for example, to the multicast address 224.0.0.1).
[0063]
The wireless terminal 31B that has received the notification switches the connection destination to the wireless access point device 12B according to the content of the notification, and receives a packet addressed to the multicast group 2 via the wireless access point device 12B. More specifically, the control unit 41 of the wireless terminal 31B first transmits a leaving notification to the effect that the terminal is leaving the multicast group 2 to the management node device 32 and the router 14 via the wireless access point device 12A. The reason why the exit notification is transmitted not only to the router 14 but also to the management node device 32 is to allow the management node device 32 to promptly update the corresponding information upon receiving the exit notification. is there. Then, after switching the connection destination to the wireless access point device 12B, the control unit 41 transmits a participation notification to the effect that it joins the multicast group 2 to the router 14 via the wireless access point device 12B, and sends the notification to the multicast group 2. When the reception of the packet is started, a participation notice indicating that fact is transmitted to the management node device 32. In the present embodiment, a case has been described in which the above-described exit notification is transmitted from the wireless terminal 31B to the management node device 32 in order to cause the management node device 32 to immediately update the correspondence information. However, the management node device 32 may periodically inquire the wireless terminal 31 about the received multicast group and the connected wireless access point device, and update the correspondence information based on a response to the inquiry. In such a case, it is not necessary to transmit the exit notification from the wireless terminal 31 to the management node device 32.
[0064]
At the time when the operation described above is completed, the correspondence information stored in the volatile storage unit 441 of the management node device 32 is in the state shown in FIG. 11, and the load applied to each wireless access point device is biased. Absent. As described above, according to the present embodiment, even when each of the plurality of wireless terminals substantially simultaneously joins a different multicast group, while avoiding useless use of the communication band of the wireless section, The bias of the load applied to each wireless access point device can be corrected.
[0065]
(4-2: Operation example 2)
Next, the wireless terminal 31A connected to the wireless access point device 12A and participating in the multicast group 1 leaves the multicast group 1 and newly enters the multicast group 3 (multicast group address: 234.1.2.5: 3 Mbps). The operation in the case of participating in is described. In addition, as a premise of the operation example described below, it is assumed that the wireless terminals 31A and 31C are connected to the wireless access point device 12A, participate in the multicast group 1, and the wireless terminals 31B and 31D are connected to the wireless access point device 12B. It is assumed that the connection has been made and the multicast group 2 has been joined. Therefore, at the start of the operation described below, the correspondence information shown in FIG. 12 is stored in the management node device 32.
[0066]
When the user is instructed to join the multicast group 3, the control unit 41 of the wireless terminal 31A performs the above-described steps SA1 and SA2. That is, the control unit 41 acquires the correspondence information from the management node device 32, and determines whether or not there is a wireless access point device that distributes the packet to the multicast group 3 based on the correspondence information.
[0067]
As described above, since both the wireless access point devices 12A and 12B do not distribute the packet addressed to the multicast group 3, the determination result in step SA2 is “No”. For this reason, the control unit 41 performs the processing of step SA4 described above, and switches the connection to the wireless access point device with the smallest load. In the present operation example, as shown in FIG. 12, the load on the wireless access point device 12B is smaller than the load on the wireless access point device 12A. The connection is switched to the device 12B to join the multicast group 3. After that, the wireless terminal 31A joins the multicast group 3 and notifies the management node device 32 that the reception of the packet transmitted to the multicast group has started. The management node device 32 updates the correspondence information based on the notification. As a result, the correspondence information stored in the management node device 32 is in a state as shown in FIG. 13, for example.
[0068]
As described above, according to the present embodiment, even when the wireless terminal 31 participating in a certain multicast group leaves the multicast group and joins a new multicast group, communication in a wireless section The load on each wireless access point device can be distributed while avoiding unnecessary use of the band.
[0069]
(5: Modification)
Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various modifications can be made within the scope of the technical idea. Note that, for example, the following modifications are possible.
[0070]
(5-1: Modification 1)
In the above-described embodiment, the management node device 32 that stores the correspondence information and manages the load applied to the wireless access point device and the multicast group to which packets are transmitted from the wireless access point device is replaced by the router 14 or the network switch 13. The case where it is provided as a device different from the above has been described. However, the function of the management node device 32 may be provided to the router 14, or the function of the management node device 32 may be provided to the network switch 13. In short, any configuration may be used as long as a device having the same function as the management node device 32 according to the present embodiment exists in one sub-network connected to the backbone network by the router 14.
[0071]
(5-2: Modification 2)
In the above-described embodiment, the case where communication is performed by transmitting and receiving packets obtained by dividing data into predetermined data sizes has been described. However, a communication unit of data in the wireless communication system according to the present invention is not limited to a packet, and may be a frame or a segment. In short, any data block including a destination may be used. Note that a frame is a data communication unit in the data link layer, and a segment is a data communication unit in the transport layer.
[0072]
(5-3: Modification 3)
In the above-described embodiment, IP multicast has been described as an example of multicast. However, the multicast executed in the wireless communication system according to the present invention is not limited to the IP multicast. For example, the multicast may be performed in accordance with a communication protocol layer (for example, a data link layer) lower than IP (that is, a network layer in the OSI reference model). Specifically, a multicast using a MAC (Media Access Control) address, which is a communication address in the data link layer, may of course be used.
[0073]
(5-4: Modification 4)
In the above-described embodiment, the case where the wireless LAN is used as an example of the wireless communication network included in the wireless communication system connected to the backbone network via the router 14 has been described. However, the wireless communication network included in the wireless communication system according to the present invention is not limited to the wireless LAN, but may be a mobile packet communication network. In short, any communication network that transmits a packet to a multicast group by designating a destination indicating the multicast group may be used.
[0074]
(5-5: Modification 5)
In the above-described embodiment, the configuration in which only one network switch 13 is connected to the router 14 has been described. However, the configuration of the wireless communication system according to the present invention is not limited to such a configuration. For example, a case where a plurality of network switches are connected in a tree shape is of course also applicable. Specifically, as shown in FIG. 14, a network switch 13A is connected to the router 14, and the network switches 13B and 13C are connected to the network switch 13A. In this case, a plurality of wireless access point devices 12 may be connected.
[0075]
【The invention's effect】
According to the present invention, when each of a plurality of wireless terminals attempts to join a different multicast group substantially simultaneously, or when a wireless terminal that has already joined a given multicast group leaves the multicast group and another multicast group In this case, even when participating in a wireless network, the load can be distributed among a plurality of wireless access point devices while avoiding useless use of a communication band in a wireless section.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an overall configuration of a wireless communication system according to the present invention.
FIG. 2 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 3 is a block diagram illustrating an example of a hardware configuration of the wireless terminal 31.
FIG. 4 is a block diagram showing an example of a hardware configuration of the management node device 32.
FIG. 5 is a diagram showing an example of a communication sequence in the wireless communication system.
FIG. 6 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 7 is a flowchart showing a flow of a process executed by a control unit 41 of the wireless terminal 31.
FIG. 8 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 9 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 10 is a flowchart showing a flow of a process executed by a control unit 41 of the management node device 32.
FIG. 11 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 12 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 13 is a diagram showing an example of correspondence information stored in the management node device 32.
FIG. 14 is a diagram illustrating an example of an overall configuration of a wireless communication system according to a fifth modification.
FIG. 15 is a diagram illustrating an example of an overall configuration of a wireless communication system using a conventional load balancing technique.
FIG. 16 is a diagram illustrating an example of an overall configuration of a wireless communication system according to Non-Patent Document 1.
FIG. 17 is a diagram showing an example of correspondence information stored in a management node device according to Non-Patent Document 1.
[Explanation of symbols]
11A, 11B, 11C, 11D, 21A, 21B, 21C, 21D, 31A, 31B, 31C, 31D: wireless terminal, 12A, 12B, 12C, 12D: wireless access point device, 13: network switch, 14: router, 22 , 32 ... management node device, 41 ... control unit, 42 ... operation unit, 43 ... wireless communication unit, 44 ... storage unit, 441 ... volatile storage unit, 442, 443 ... nonvolatile storage unit, 45 ... wired communication unit, 46 ... Bus.

Claims (7)

Storage means;
Acquiring, for each wireless access point device, load information indicating a load on a wireless access point device transmitting a data block to one or more multicast groups and an identifier for uniquely identifying the multicast group; Writing means for writing to the
Based on the storage content of the storage unit, a determination unit that determines whether there is a bias in the load applied to each of the wireless access point devices,
When it is determined by the determination unit that the load applied to each of the wireless access point devices is biased, the multicast group in which data blocks are transmitted from the wireless access point device with the largest applied load Identifying means for identifying at least one multicast group from
Requesting means for requesting a wireless terminal participating in the multicast group specified by the specifying means to switch connection to a wireless access point apparatus with the smallest load. The management node device according to claim 1, wherein the specifying unit specifies a multicast group based on the number of participating wireless terminals. Connecting means for connecting to a wireless access point device transmitting a data block to a wireless section,
The correspondence information in which load information indicating a load applied to the wireless access point device and an identifier for uniquely identifying a destination to which a data block is transmitted from the wireless access point device is written for each wireless access point device is described. Receiving means for receiving via the wireless access point device connected by the connecting means,
Input means for inputting a user instruction;
When the instruction input by the input unit is an instruction indicating that the user should join a certain multicast group, it is determined whether or not there is a wireless access point device transmitting a data block addressed to the multicast group. Determining means for determining based on the correspondence information received by the receiving means;
When the determination unit determines that there is a corresponding wireless access point device, switches the connection to the wireless access point device, and conversely, when the determination unit determines that there is no corresponding wireless access point device And a control means for controlling the connection means so as to switch the connection to the wireless access point device with the smallest load. A wireless access point device for transmitting a data block addressed to one or more multicast groups;
Management for acquiring and storing, for each of the wireless access point devices, load information indicating a load applied to the wireless access point device and an identifier for uniquely identifying a multicast group to which a data block is transmitted from the wireless access point device. A node device;
With
The management node device,
Based on the load information, determine whether there is a bias in the load on each of the wireless access point device,
When it is determined that there is a bias, at least one multicast group is specified from among the multicast groups whose data blocks are transmitted from the wireless access point device with the largest load,
A wireless communication system requesting wireless terminals participating in a specified multicast group to switch connection to a wireless access point device with the smallest load. A management node device that communicates with a wireless access point device that transmits a data block addressed to one or more multicast groups includes load information indicating a load applied to the wireless access point device and a data block from the wireless access point device. A first step of acquiring, for each wireless access point device, an identifier that uniquely identifies the multicast group being transmitted;
A second step in which the management node device detects, based on the load information obtained in the first step, that there is a bias in the load applied to each of the wireless access point devices;
A third step in which the management node device specifies at least one multicast group from among the multicast groups whose data blocks are transmitted from the wireless access point device with the largest load;
The management node device requests a wireless terminal participating in the multicast group specified in the third step to switch a connection destination to a wireless access point device with the smallest load. 4. A load distribution method comprising: Computer equipment,
Storage for acquiring and storing, for each wireless access point device, load information indicating a load on a wireless access point device transmitting a data block to one or more multicast groups and an identifier for uniquely identifying the multicast group. Features and
Based on the load information stored by the storage function, a determination function to determine whether there is a bias in the load on each of the wireless access point device,
When it is determined by the determination function that the load applied to each of the wireless access point devices is biased, among the multicast groups that are transmitting data blocks from the wireless access point device with the largest applied load A identifying function for identifying at least one multicast group from:
A program for realizing a request function for requesting a wireless terminal participating in the multicast group specified by the specific function to switch connection to a wireless access point device with the smallest load. Computer equipment,
A connection function for connecting to a wireless access point device that transmits a data block to a wireless section,
The correspondence information in which load information indicating a load applied to the wireless access point device and an identifier for uniquely identifying a destination to which a data block is transmitted from the wireless access point device is written for each wireless access point device is described. A receiving function for receiving via a wireless access point device connected by the connecting function,
An input function for inputting a user instruction,
If the instruction input by the input function is an instruction indicating that it should join a certain multicast group, it is determined whether or not there is a wireless access point device transmitting a data block addressed to the multicast group. A determining function for determining based on the correspondence information received by the receiving function,
When it is determined by the determination function that there is a corresponding wireless access point device, the connection is switched to the wireless access point device, and conversely, when it is determined by the determination function that there is no corresponding wireless access point device , A control function for controlling the connection function so as to switch the connection to the wireless access point device with the smallest load.

Images