JP2008277919A - Wireless lan access point and wireless lan terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve connection quality such as loss probability, in a wireless LAN system. <P>SOLUTION: The number of simultaneous connections of wireless LAN access points is monitored, and when the number of sessions exceeds a threshold, the communication mode of a wireless LAN terminal is automatically switched to an ad hoc mode. The communication mode of the terminal is switched to the ad hoc mode, and then when a speech communication is started, origination and termination are performed through an ad hoc network. Further, the maximum number of connections is itemized by definitions corresponding to the purposes of use for origination, termination, emergency communication, roaming, etc., and a dedicated free band is prepared for top-priority communication, so that even when the call loss of the area of an object terminal is large, the call loss is decreased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless LAN access point and a wireless LAN terminal, and more particularly to a wireless LAN terminal and a wireless LAN access point that switch communication modes according to a signal from a wireless LAN access point that monitors a data amount during communication.

  Currently, voice communication by wireless LAN is actively performed. In voice communication using a wireless LAN, it is essential to maintain a certain level of voice quality and connection quality when connected to a telephone network. Therefore, in order to ensure voice quality, the wireless LAN access point monitors the number of connections and traffic volume during communication, and performs control (call admission control) so that new calls are not accepted when a certain threshold is exceeded. There may be. Further, in order to ensure connection quality such as a call loss rate, it is necessary to determine the number of wireless LAN access points, station design, and the number of simultaneous connections according to the number of wireless LAN terminals.

  However, a load on a specific wireless LAN access point may be concentrated as the floor layout is changed and the number of people is increased / moved. Since the number of simultaneous connections is defined for voice quality, there is little degradation. However, the connection quality (call loss rate) is considered to deteriorate.

  In Patent Document 1, in order to increase the throughput of the entire network, when the traffic volume to be monitored is higher than a predetermined value, an infrastructure mode is set for a wireless LAN client in response to a connection request between wireless LAN terminals. Describes an invention for switching the communication from the ad hoc mode to the ad hoc mode.

JP 2005-86234 A

  When a VoIP (Voice over Internet Protocol) network is configured in a wireless local area network (LAN) system, the load on a specific wireless LAN access point is concentrated as the floor layout is changed and the number of people increases / moves. There is. At this time, the connection quality is considered to deteriorate. That is, there is a high possibility that a call loss will occur near the area of the access point with a large call volume compared to other areas.

  The invention described in Patent Document 1 switches communication between two wireless LAN terminals under a specific access point to an ad hoc mode, and connects to a wireless LAN terminal under another access point, a telephone network Connection with is not considered.

  The above problem is that the number of wireless LAN access points connected simultaneously is monitored, and when the number of sessions exceeds a threshold, the communication mode of the wireless LAN terminal is switched to the ad hoc mode. By switching the communication mode of the terminal to the ad hoc mode, outgoing / incoming calls are made via the ad hoc network when starting a voice call. In addition, regarding the breakdown of the maximum number of connections, it is defined according to the application, such as outgoing, incoming, emergency communication, roaming, etc., by preparing a dedicated free band for the highest priority communication, Even when the call volume in the area of the target terminal is large, the call loss rate is reduced.

  Also, the first wireless LAN terminal is accommodated, the voice communication session between the first wireless LAN terminal and the second wireless LAN terminal is mediated, the number of voice communication sessions is monitored, and the number of sessions is This can be achieved by a wireless LAN access point including a communication state monitoring unit that notifies the wireless LAN terminal to transition to the ad hoc mode when the threshold of 1 is exceeded.

  Further, a LAN mode switching unit that switches the communication mode from the infrastructure mode to the ad hoc mode or from the ad hoc mode to the infrastructure mode based on the notification from the wireless LAN access point, and the first other wireless LAN in the ad hoc mode This can be achieved by a wireless LAN terminal including a data relay unit that transfers communication from the terminal to another wireless client.

  By switching the communication mode of the wireless LAN terminal between the infrastructure mode and the ad hoc mode according to the load state of the access point, it is possible to improve connection quality and to distribute traffic load.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using examples. Note that the same reference numerals are assigned to the same parts, and description thereof is not repeated.

  The configuration of the wireless LAN terminal and the wireless LAN access point will be described with reference to FIGS. Here, FIG. 1 is a functional block diagram of the wireless LAN terminal. FIG. 2 is a functional block diagram of the wireless LAN access point.

  In FIG. 1, a wireless LAN terminal 100 includes a LAN controller 101, a wireless communication unit 102, a wireless LAN communication mode switching unit 103, a data processing unit 104, a terminal information possessing unit 105, a data relay unit 106, and an antenna 107. The LAN controller 101 performs packet assembly, disassembly, communication control, and the like. The wireless communication unit 102 performs conversion between a wired signal and a wireless signal, and transmits and receives the wireless signal. The wireless LAN communication mode switching unit 103 switches the communication mode (infrastructure mode, ad hoc mode) of the wireless LAN terminal 100 according to an instruction from the wireless LAN access point. The data processing unit 104 executes an application. The terminal information possessing unit 105 holds terminal information indicating whether it is operating in the ad hoc mode or in the infrastructure mode. The data relay unit 106 is realized by hardware, and transfers data received in the ad hoc mode to another wireless LAN terminal or a wireless LAN access point. Note that the transfer mode may be an ad hoc mode or an infrastructure mode.

  In FIG. 2, a wireless LAN access point (hereinafter referred to as wireless AP) 200 includes a LAN controller 201, a wireless communication unit 202, a communication state monitoring unit 203, a data processing unit 204, and an antenna 205. The LAN controller 201 performs packet assembly, disassembly, communication control, and the like. The wireless communication unit 202 performs conversion between a wired signal and a wireless signal, and transmits and receives the wireless signal. The communication state monitoring unit 203 monitors the call channel and sends information for switching the communication mode (infrastructure mode, ad hoc mode) of the wireless LAN terminal 100. The data processing unit 204 executes an application.

  In the default infrastructure mode, the wireless AP 200 and the wireless LAN terminal 100 transmit and receive data between the wireless communication unit 102 and the wireless communication unit 202 via the antenna 107 and the antenna 205. Data received by the wireless LAN terminal 100 is transferred to various applications by the data processing unit 104.

  The communication state monitoring unit 203 always monitors the number of sessions and traffic during a call with its own wireless AP 200. When the number of sessions in a call exceeds a preset threshold, the wireless LAN terminal 100 is notified via the wireless communication unit 202 to communicate from the infrastructure mode to the ad hoc mode.

  The communication mode switching signal sets the switching information in 4-octet data called IBSS (Independent Basic Service Set) Parameter Set included in the information of the beacon signal and the probe response. The communication mode switching signal may be anything other than IBSS Parameter Set as long as the switching signal can be uniquely specified.

  Even if the communication mode is switched to the ad hoc mode, the wireless LAN terminal 100 recognizes the number transmitted by the terminal, and when the emergency communication is necessary, the communication mode of the terminal is set to the infrastructure mode. In the infrastructure mode, communication is started using an emergency communication channel described later.

  A hardware configuration of the wireless LAN terminal and the wireless AP will be described with reference to FIGS. 3 and 4. Here, FIG. 3 is a hardware block diagram of the wireless LAN terminal. FIG. 4 is a hardware block diagram of the wireless AP.

  In FIG. 3, a wireless LAN terminal 100 includes a central processing unit (CPU) 111 connected to an internal communication line 114 such as a bus, a storage device 112, a wireless communication unit 102 connected to an antenna 107, a data relay unit 106, an external The interface 113 is configured. The storage device includes a main memory (M / M) 121 and forms a terminal information processing unit 105. The CPU 111 executes the program stored in the main memory 121, thereby realizing the functions of the LAN controller 101, the wireless LAN mode switching unit 103, and the data processing unit 104 described in FIG.

  4, the wireless AP 200 includes a central processing unit (CPU) 211 connected to an internal communication line 214 such as a bus, a main memory 212, a wireless communication unit 202 connected to an antenna 205, and an external interface 213. . The CPU 211 executes the program stored in the main memory 212, thereby realizing the functions of the LAN controller 201 and the data processing unit 204 described with reference to FIG.

  With reference to FIG. 5, the passive scan defined in IEEE (Institute of Electrical and Electronic Engineers) 802.11 will be described. Here, FIG. 5 is a sequence diagram for explaining processing in which a wireless LAN terminal belongs to a wireless AP.

  In FIG. 5, the wireless AP 200 periodically transmits a beacon signal (S201). The wireless LAN terminal 100 that has received the beacon signal sends an authentication request to the wireless AP 200 to perform terminal authentication (S202). Here, the authentication is an operation in which the wireless AP 200 verifies the validity of the wireless LAN terminal 100, and verifies the validity of the MAC address (Media Access Control address).

  The wireless AP 200 that has received the authentication request returns an authentication response (S203). Thereafter, the wireless LAN terminal 100 transmits an attribution request (S204), and the wireless AP 200 returns an attribution response (S205). As described above, the wireless LAN terminal 100 belongs to the wireless AP 200 and can transmit and receive data.

  When a wireless LAN terminal newly connected to the LAN is switched to the ad hoc mode, the wireless AP 200 places a switching signal on the beacon signal. The wireless LAN terminal 100 that has received the switching signal does not exchange with the wireless AP 200 after the authentication request 202. The wireless LAN terminal 100 switched to the ad hoc mode performs subsequent communication via another wireless LAN terminal. If the radio wave from another wireless AP is stronger, the wireless LAN terminal 100 may not switch the communication mode even if it receives a signal for switching to the ad hoc mode.

  With reference to FIG. 6, an active scan defined in IEEE 802.11 will be described. Here, FIG. 6 is a sequence diagram for explaining processing in which a wireless LAN terminal belongs to a wireless AP.

  In FIG. 6, the wireless LAN terminal 100 transmits a probe request when belonging to the wireless AP 200 (S301). The wireless AP 200 that has received the probe request returns a probe response (S302). The wireless LAN terminal 100 that has received the probe response transmits an authentication request to the wireless AP 200 that has transmitted the probe response in order to perform terminal authentication (S303). Since step 303 to step 306 are the same as step 202 to step 205 in FIG. 5, description thereof will be omitted.

  When the wireless LAN terminal newly connected to the LAN is switched to the ad hoc mode, the wireless AP 200 puts a switching signal on the probe response 302. The wireless LAN terminal 100 that has received the switching signal does not exchange with the wireless AP 200 after the authentication request. The wireless LAN terminal 100 switched to the ad hoc mode performs subsequent communication via the other wireless LAN terminal 100 '. If the radio wave from another wireless AP is stronger, the wireless LAN terminal 100 may not switch the communication mode even if it receives a signal for switching to the ad hoc mode.

  With reference to FIG. 7, the allocation of the call channel of the wireless AP will be described. Here, FIG. 7 is a diagram for explaining the allocation of the call channel of the wireless AP. In FIG. 7, when the number of channels of the call channel 400 of the wireless AP 200 is 10, 5 channels for the outgoing channel 401, 1 channel for the emergency communication channel 402, 2 channels for the roaming channel 403, 2 for the incoming channel 404 Allocate a channel.

  When the number of sessions of the transmission channel 401 reaches a preset threshold A (5 in this case), the communication mode of the wireless LAN terminal 100 that exists in the wireless AP call area and is not making a call is set to the ad hoc mode. The wireless AP 200 transmits a signal for switching to a beacon signal or a probe response.

  In addition, when the number of sessions becomes less than the threshold A, if the mode is immediately switched to the infrastructure mode, the communication mode is frequently switched and the communication becomes unstable. For this reason, when the threshold value B is smaller than the threshold value A (here, 3) or less, the wireless AP 200 transmits a signal for switching to the infrastructure mode by a beacon signal or a probe response.

  With reference to FIG. 8 and FIG. 9, the wireless AP process for switching from the infrastructure mode to the ad hoc mode and from the ad hoc mode to the infrastructure mode will be described. Here, FIG. 8 is a flowchart of switching between modes of the passive scan. FIG. 9 is a flowchart of switching between modes of active scan.

  In FIG. 8, the wireless AP 200 first determines whether the communication mode being transmitted is the infrastructure mode and the calling channel being used is greater than or equal to the threshold value A (S501). When the calling ch being used is equal to or greater than the threshold A, information to be communicated in the ad hoc mode is notified on the beacon signal (S504), and the process proceeds to step 501. When the communication mode is not the infrastructure mode in step 501, or if the calling channel used in the infrastructure node is less than the threshold A, the process proceeds to step 502.

  Next, the wireless AP 200 determines whether or not the communication mode is the ad hoc mode and the calling channel being used is equal to or less than the threshold value B (S502). If YES, information for communication in the infrastructure mode is notified on the beacon signal (S503), and the process proceeds to step 501. On the other hand, if NO at step 502, the process proceeds to step 501 as it is.

  In FIG. 9, first, the wireless AP 200 determines whether the communication mode being transmitted is the infrastructure mode and the calling channel being used is greater than or equal to the threshold A (S511). When the calling channel being used is equal to or greater than the threshold A, information to be communicated in the ad hoc mode is reported on the probe response (S514), and the process proceeds to step 511. If the communication mode is not the infrastructure mode in step 511, or if the calling channel used by the infrastructure node is less than the threshold A, the process proceeds to step 512.

  Next, the wireless AP 200 determines whether or not the communication mode is the ad hoc mode and the calling channel being used is equal to or less than the threshold value B (S512). If YES, information for communication in the infrastructure mode is reported on the probe response (S513), and the process proceeds to step 511. On the other hand, if NO at step 512, the process proceeds to step 511 as it is.

With reference to FIG. 10, the operation in each channel in the infrastructure mode and the operation in the ad hoc mode will be described. Here, FIG. 10 is a block diagram of the wireless LAN system.
In FIG. 10, the wireless LAN system 500 includes two wireless APs 200-1 and 200-2 and a plurality of wireless LAN terminals 100. The wireless LAN terminal 100I is a terminal operating in the infrastructure mode, and the wireless LAN terminal 100A is a terminal operating in the ad hoc mode. Further, the description of simply “wireless LAN terminal 100” does not specify a mode.

  Each wireless LAN terminal 100 is set to the infrastructure mode by default. Therefore, the wireless LAN terminal 100I-1 to wireless LAN terminal 100I-4 whose communication mode is the infrastructure mode performs data transmission / reception with the wireless AP 200-1 or the wireless AP 200-2 in the infrastructure mode by the solid line arrow. Yes. Here, in the area of the wireless AP 200-1, it is assumed that the wireless AP 200-1 is transmitting the ad hoc mode.

  The wireless LAN terminal 100A-6 switched to the ad hoc mode performs data transmission / reception with the wireless AP 200-2 via the wireless LAN terminals 100-7 and 100I-8 including the data relay unit 106. Here, ad hoc communication indicated by broken-line arrows is performed between the wireless LAN terminal 100A-6 and the wireless LAN terminal 100-7, and between the wireless LAN terminal 100-7 and the wireless LAN terminal 100I-8. On the other hand, communication 618 in the infrastructure mode is established between the wireless LAN terminal 100I-8 and the wireless AP 200-2.

  Since the wireless AP 200-1 in the state of transmitting the ad hoc mode has separate channels 402 and 404 for the emergency / incoming terminal 100I-5, these communications directly transmit / receive data to / from the wireless AP 200-1. Can do. In addition, when the roaming terminal 100I-9 in the area of the wireless AP 200-2 moves to the area of the wireless AP 200-1, the wireless AP 200-1 separates the roaming channel 403 from the voice path already in communication. Therefore, these communications can directly transmit / receive data to / from the wireless AP 200-1.

It is a functional block diagram of a wireless LAN terminal. It is a functional block diagram of a wireless LAN access point. It is a hardware block diagram of a wireless LAN terminal. It is a hardware block diagram of wireless AP. It is a sequence diagram explaining a process (passive scan) to which a wireless LAN terminal belongs to a wireless AP. It is a sequence diagram explaining a process (active scan) to which a wireless LAN terminal belongs to a wireless AP. It is a figure explaining allocation of the call channel of wireless AP. It is a flowchart of switching between modes of passive scanning. It is a flowchart of switching between modes of active scan. Network in wireless LAN communication mode automatic switching system

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Wireless LAN terminal, 101 ... LAN controller, 102 ... Wireless communication part, 103 ... Wireless LAN mode switching part, 104 ... Data processing part, 105 ... Terminal information possession part, 106 ... Data relay part, 107 ... Antenna, 111 ... CPU, 112 ... Storage device, 113 ... External interface, 114 ... Internal communication line, 121 ... Main memory, 200 ... Wireless AP, 201 ... LAN controller, 202 ... Wireless communication unit, 203 ... Communication state monitoring unit, 204 ... Data processing 205, antenna, 211, CPU, 212, main memory, 213, external interface, 214, internal communication line, 400, call channel, 500, wireless LAN system.

Claims (4)

In a wireless LAN access point that accommodates a first wireless LAN terminal and mediates a voice communication session between the first wireless LAN terminal and the second wireless LAN terminal,
A wireless LAN access point comprising: a communication state monitoring unit that monitors the number of voice communication sessions and notifies a wireless LAN terminal to transition to an ad hoc mode when the number of sessions exceeds a first threshold . The wireless LAN access point according to claim 1,
The communication state monitoring unit notifies a wireless LAN terminal to transition to an infrastructure mode when the number of sessions becomes equal to or smaller than a second threshold value smaller than the first threshold value. point. The wireless LAN access point according to claim 1 or 2,
The wireless LAN access point, wherein the communication state monitoring unit transmits a beacon signal or a probe response including a mode transition notification.   A LAN mode switching unit for switching the communication mode from the infrastructure mode to the ad hoc mode or from the ad hoc mode to the infrastructure mode based on the notification from the wireless LAN access point; and the first other wireless LAN in the ad hoc mode A wireless LAN terminal comprising: a data relay unit that transfers communication from the terminal to another wireless client.

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