JP2008060711A - Wireless communication system and wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system and a wireless communication device which can appropriately select a terminal to be operated as a wireless base station in accordance with terminal placement. <P>SOLUTION: The wireless communication system includes a plurality of first wireless communication devices capable of operating as a radio base station; a transmission means which transmits an investigation request frame, including an address of a wireless communication device to be investigated, to the plurality of first wireless communication devices; a reception means which receives investigation results which are obtained, by transmitting a test frame to the address from the plurality of first wireless communication devices, in response to reception of the investigation request frame and show the numbers of terminals which the plurality of first wireless communication devices can communicate with, respectively; and a base station selection means which selects the first wireless communications device capable of communicating with the largest number of terminals, among the plurality of first wireless communication devices as the base station, on the basis of the investigation results. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication system and a radio communication apparatus that appropriately select a terminal to operate as a radio base station from a plurality of radio terminals according to the terminal arrangement.

In a wireless communication system in which there are a plurality of wireless terminals having both a function operating as a wireless terminal and a function operating as a wireless base station, a wireless base station that manages the entire wireless communication system is selected from these wireless terminals. A technique for selecting a terminal, that is, a radio base station is known. The conventional method of selecting a wireless base station ranks each wireless terminal according to three values: power supply status (whether it is battery-powered), the highest supported transmission rate, and the supported bandwidth. The terminal with the highest rank is selected. When ranks as comparison conditions are equal between terminals, a wireless terminal to be a radio base station is selected by using a value obtained by converting a MAC address into an integer representation as a further comparison condition ( For example, refer nonpatent literature 1).
IEEE802.11e Draft 3.0, IEEE Std 802.11e / D3.0, May 2002

  In the above prior art, among the three values used as comparison conditions, the maximum supported transmission rate and the supported bandwidth are usually set to the same value among many terminal devices. Since there are only two values for the power supply status, battery-powered / non-battery-driven, the conditions for selecting a wireless base station from multiple wireless terminals are mostly MAC address comparisons. End up.

  In addition, even if the above values are different for each terminal and can be used as a selection condition, these values are based on the location information of each terminal, the radio propagation environment in which each terminal is located, and the current time between the terminals. Does not reflect the communication status of Therefore, if the radio base station is changed according to the above selection method, it may not be possible to accommodate a large number of terminals belonging to the wireless communication system until now, or it may not be possible to accommodate terminals that are gateways for connection to the Internet. And the number of terminals to be accommodated is reduced because the selected base station is located at the end of the terminal arrangement.

  In addition, in wireless LAN product forms that are currently sold in the market, where each wireless terminal is divided into a wireless base station and a wireless terminal, radio waves reach the entire environment for building a wireless communication system. It is necessary for the user to find a position to do this and install a radio base station there. At this time, the user must perform a complicated task of searching for the location of the wireless base station, and if the power location or the Internet connection cable does not come to the installation location, use a cable or extension cord. It is necessary to bring it. Furthermore, in the configuration currently sold in the market, it is necessary to purchase a wireless LAN product dedicated to the wireless base station, which increases the cost burden on the user.

  Therefore, an object of the present invention is to provide a radio communication system and a radio communication method for appropriately selecting a terminal to operate as a radio base station from a plurality of radio terminals according to the terminal arrangement.

  A wireless communication system according to an aspect of the present invention includes a plurality of first wireless communication devices operable as a wireless base station, and a plurality of first wireless communication devices including an investigation request frame including an address of a wireless communication device to be investigated. Transmitting means for transmitting to the apparatus, and each of the plurality of first wireless communication apparatuses transmitting the test frame toward the address by receiving the investigation request frame, and the plurality of first wireless communication Receiving means for receiving a survey result indicating the number of terminals that each of the devices can communicate with, and a first wireless communication device having the largest number of terminals capable of communication based on the survey result of each of the plurality of first wireless communication devices Base station selection means for selecting a radio base station from among them.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communications system and radio | wireless communication apparatus with which the terminal which should operate | move as a radio base station are selected appropriately according to terminal arrangement can be provided.

  Hereinafter, a wireless communication system adopting IEEE802.11 as a wireless communication system will be described. Note that the wireless communication system based on IEEE802.11 is only one of the wireless communication systems to which the present invention can be applied, and the present invention can be applied to other wireless communication systems in general. In the following description, a radio base station is denoted as “access point (AP)”, and a radio terminal or a radio communication device connected to the radio base station is denoted as “terminal (STA)”.

(First embodiment)
FIG. 1 is a diagram illustrating an arrangement of wireless terminals related to the wireless communication system according to the present embodiment, and FIG. 2 is a block diagram illustrating a configuration of the wireless communication apparatus according to the present embodiment.

  As shown in FIG. 2, the wireless communication apparatus 201 includes a transmission processing unit 202, a reception processing unit 203, a survey unit 204, a terminal control unit 205, and a wireless communication system management unit 206, and can operate as an STA. It can also operate as an AP. The transmission processing unit 202 performs transmission processing of control frames such as survey request frames and data frames. The reception processing unit 203 performs reception processing of control frames such as survey request frames and data frames. The investigation unit 204 performs investigation processing by exchanging test frames. The terminal control unit 205 performs internal control during data transmission / reception processing and control frame transmission / reception processing. When operating as an AP, the wireless communication system management unit 206 manages information on a plurality of terminals under its control.

  In the wireless communication system of this embodiment, as shown in FIG. 1, first, STA4 (AP) 104 is operated as an access point, and STA1 101, STA2 102, STA3 103, STA5 105 are operated as access points of STA4 (AP) 104. A BSS (Basic Service Set) to which a total of four terminals belong is constructed and communicates. At this time, a method from when the STA 6 106 outside the communication range 107 of the STA 4 (AP) 104 operating as an access point starts up and belongs to the BSS will be described below. Note that all STAs shown in FIG. 1 are wireless communication apparatuses that can operate as either the AP or the STA shown in FIG. However, it is not necessary for all terminals in the BSS to be the wireless communication apparatus according to the present invention shown in FIG. 2, and only the STA4 (AP) 104 and several other STAs are wireless communication apparatuses according to the present invention. The STA may be a conventional wireless communication device.

  FIG. 3 is a message sequence chart showing the procedure of AP function movement in the wireless communication system of this embodiment. 4 is a flowchart of the operation of the STA 6 in FIG. 1 newly joining the wireless communication system, and FIG. 5 is a diagram of the STA 6 in FIG. 1 newly joining the wireless communication system and the STA 4 that was the AP before joining the STA 6. FIG. 6 is a flowchart of the operation of STA4, which is the original AP.

(1-1-1. Discovery of BSS by STA6)
Access point STA4 (AP) 104 and a total of four terminals, STA1 101, STA2 102, STA3 103, and STA5 105, establish a BSS (Basic Service Set) and perform communication. At this time, it is assumed that the STA6 106 is activated (step 1 in FIG. 4). STA6 performs normal scan processing. However, since the STA 6 is located outside the communication range 107 of the access point STA4 (AP) 104 as shown in the terminal arrangement of FIG. 1, the frame transmitted by the access point STA4 (AP) 104 cannot be received. For this reason, AP cannot be found (step 2 in FIG. 4).

  As shown in the terminal arrangement in FIG. 1, the STA 6 106 cannot communicate with the STA 4 (AP) 104, but can communicate with the STA 2 102. For this reason, during the above scan process, the AP cannot be detected by receiving the data transmitted from the STA2 102 to the STA4 (AP) 104, but the BSS is found (FIG. 4). Step 3).

(1-1-2. STA6 connection request frame is notified to STA2)
The STA 6 106 that has discovered the BSS transmits a connection request frame requesting connection to the BSS to the STA 2 102 (step 4 in FIG. 4). The STA 6 106 that has transmitted the connection request frame waits for a response frame for the connection request frame to be transmitted from the STA 2 102 (step 5 in FIG. 4).

(1-1-3. STA2 relays connection request frame received from STA6 to AP)
The STA2 102 receives the connection request frame for requesting connection from the STA6 106 to the BSS during communication (step 1 in FIG. 5) belonging to the BSS managed by the STA4 (AP) 104 (step in FIG. 5). 2). The STA2 102 that has received the connection request frame relays the connection request frame to the STA4 (AP) 104 (step 3 in FIG. 5). Thereafter, the STA2 102 waits for a reply from the STA4 (AP) 104 to the connection request frame transmitted for relay (step 4 in FIG. 5).

(1-1-4. AP receives STA6 connection request and sends a survey request frame)
While the STA4 (AP) 104 establishes a BSS as an AP and performs communication (step 1 in FIG. 6), the connection request frame to the BSS from the STA6 106 relayed by the STA2 102 is received (FIG. 6). 6 step 2). The STA4 (AP) 104 that has received the connection request frame wants to connect to the BSS when the STA6 106 that is in a position where it cannot communicate with its own station because the connection request frame has been relayed, but communicates with the current AP. Recognize that you cannot connect because you cannot. In response, STA4 (AP) 104 can communicate with all STAs connected to the current BSS, and there is no new AP candidate that can connect with STA6 106 that wants to newly connect. (Step 3 in FIG. 6).

  Therefore, STA4 (AP) 104 has a list of MAC addresses of all STAs connected to the BSS, a list of MAC addresses of STAs connected to the Internet among the STAs, and STA6 106, which is a new STA. A survey request frame including the MAC address is created (step 4 in FIG. 6). The created survey request frame is transmitted with a broadcast address to notify all subordinate STAs (step 5 in FIG. 6). At this time, the investigation request frame may be transmitted to all the STAs using a unicast address without being transmitted using the broadcast address. When transmitting with a unicast address, each STA is transmitted by transmitting only to the wireless communication apparatus having a function capable of operating as either the AP or the STA shown in FIG. The number of transmissions of unicast addresses can be reduced after receiving delivery confirmation from.

(1-1-5. STA2 relays survey request frame to STA6)
When the STA2 102 waiting for a response to the connection request frame in step 4 in FIG. 5 receives the investigation request frame transmitted from the STA4 (AP) 104 with the broadcast address (step 5 in FIG. 5), the relayed connection request is received. Recognizes that the STA4 (AP) 104 has accepted the frame request. Next, in order to notify the STA 6 106 that the STA 4 (AP) 104 has accepted the STA 6 106 request, the search request frame is relayed to the STA 6 106 (step 6 in FIG. 5).

  The STA 6 106 waiting for a response to the connection request frame in step 5 in FIG. 4 receives the investigation request frame from the STA 4 (AP) 104 relayed through the STA 2 102 (step 6 in FIG. 4). By receiving this investigation request frame, the STA6 106 knows that the AP has received a connection request to the BSS that has been requested to the AP by the relay of the STA2 102 (step 7 in FIG. 4). At the same time, the MAC address of the STA4 (AP) 104, which is the AP currently managing the BSS, is also known.

(1-1-6. Investigation by test frame)
The STA4 (AP) 104 that broadcasts or unicasts the survey request frame, the STA1 102, STA3 103, STA5 105 that received the survey request frame, and the survey request frame transmitted from the STA4 (AP) 104 to the STA6 106 The STA6 106 that has received the relayed STA2 102 and the survey request frame relayed by the STA2 102 conducts a survey on, for example, “the number of communicable terminals” and “the total received power of the test frame” by transmitting and receiving test frames. (Step 8 in FIG. 4, Step 7 in FIG. 5, Step 6 in FIG. 6). These “number of communicable terminals” and “total value of test frame received power” are related to the arrangement of each terminal and change depending on the appearance of a terminal requesting connection to the BSS and a terminal disconnecting from the BSS. To do.

  In the investigation, each terminal unicasts a control frame for investigation as a test frame to all other terminals in the BSS and STA6. This check control frame requires an acknowledgment (ACK) frame. For example, STA1 transmits only one test frame to a total of five terminals, STA2, STA3, STA4, STA5, and STA6, and checks whether an ACK frame is returned. When an ACK frame is returned from the test frame transmission destination terminal, it is determined that communication with the test frame transmission destination terminal is possible. The interval until the ACK response to the test frame is the same as the interval until the ACK response to the normal IEEE802.11 unicast data. If no ACK is returned for the test frame, repeat the process until the test frame reaches RetryLimit or the lifetime of the test frame elapses. If the ACK frame is still not returned, the terminal It is determined that communication is impossible. Further, as this test frame, a Null frame or a QoS Null frame defined by IEEE802.11 may be used.

  When the test frame is transmitted and the ACK frame returned from each terminal is received, the total value of the received power is also checked at the same time. As an investigation method, the reception power value of the ACK frame received after transmitting the test frame is extracted, and the total value of these values is calculated. At this time, if each terminal is performing transmission power control, there is no point in collecting the total received power value, so transmission power control is turned OFF when an ACK frame is returned to the test frame. Each terminal has a method of turning off transmission power control only when an ACK frame is transmitted when a test frame is received, and a method of turning off transmission power control during the investigation period started after receiving the investigation request frame. .

  In addition, as a method for collecting different survey results, the same method is used for test frame transmission and ACK reply operation, but the collection method of “number of communicable terminals” and “total received power of test frame” is as follows: There is also a way to do this. As a method for measuring the “number of communicable terminals”, each terminal can also adopt a method of “number of communicable terminals” indicating how many terminals have received the test frame. Alternatively, there is a method in which the number of terminals that satisfy two conditions of receiving an ACK for the test frame transmitted by the terminal and also receiving the test frame from the terminal is set as the “number of communicable terminals”. . As “the total value of the received power of the test frame”, instead of collecting the total value of the received power of the ACK frame as described above, the received power value of the test frame is taken out when receiving the test frame, The total value of these values may be a “total value of received power of test frames”. At this time, the transmission power control must not be used for transmitting the test frame.

(1-1-7. Collection of survey results by AP)
Each terminal that has completed the investigation by the test frame transmission notifies the STA4 (AP) 104 of the investigation result. As a result of the notification to be notified, it is notified whether or not communication with all terminals other than STA6 that belonged to the BSS first is possible, whether or not communication with STA6 is possible, the total value of received power collected at the time of test frame transmission and reception, and the like. Alternatively, the total number of communicable terminals and the received power may be notified. At this time, since the STA6 106 cannot directly communicate with the STA4 (AP) 104, the STA2 102 notifies the STA2 102 of the investigation result (step 10 in FIG. 4), and the AP function can move to another terminal to detect the BSS. It waits until it becomes (step 11 of FIG. 4).

  The STA2 102 first notifies the STA4 (AP) 104 of the investigation result of its own station (step 8 in FIG. 5). Next, when the investigation result is received from the STA 6 106 (step 9 in FIG. 5), the notified investigation result of the STA 6 is relayed to the STA 4 (AP) 104 (step 10 in FIG. 5). Thereafter, it waits for STA4 (AP) 104 to determine whether to move the AP function to a terminal other than STA4 or leave it as it is (step 11 in FIG. 5).

(1-1-8. AP function switching judgment)
In STA4 (AP) 104, the investigation result of the local station is held in the investigation unit 204 in the wireless communication apparatus 201. Thereafter, the investigation results notified from each terminal are collected (step 7 in FIG. 6), and the investigation unit 204 determines whether or not to move the AP function to another terminal.

  In this embodiment, assuming that STA6 106 cannot communicate with STA1, STA3, STA4, STA5 and all other terminals can communicate with each other, in addition to all the terminals that only STA2 belongs to the existing BSS, Although it can communicate with a total of 5 units of STA6, other terminals in BSS can communicate with only 4 units other than STA6. STA6 can communicate with STA2 only. At this time, the STA4 (AP) 104 compares the notified survey results and determines that only the STA2 can communicate with the STA6 in addition to all the terminals in the BSS, so that the STA2 moves the AP function ( Step 11 in FIG.

  Alternatively, STA6 cannot communicate with STA1, STA3, and STA4, but if STA2 and STA5 can communicate with each other, STA2 and STA5 communicate with all 5 terminals of STA6 in addition to all terminals that belonged to the existing BSS. it can. At this time, since there are two terminals, STA2 and STA5, which are candidates for moving the AP function, the total value of the received power in STA2 and STA5 is compared to determine the terminal to move the AP function. For example, in the present embodiment, it is assumed that the total value of received power is larger in STA2 as a result of comparing the total value of received power. In this case, it is determined to move the AP function to STA2 (step 11 in FIG. 6).

  If there is no terminal that can communicate with all terminals in BSS but also with STA6, the AP function decides not to move from STA4 (AP) 104 as it is, and STA6 via STA2 Is notified that the connection request to the BSS notified first is rejected (step 12 in FIG. 6).

  In AP function switching (base station selection), AP function switching is performed for the terminal that can communicate with one or more terminals that can communicate with the outside of the BSS (for example, the Internet) and has the largest number of terminals that can communicate. It may be the destination.

(1-1-9. Switching AP function)
The investigation unit 204 of the STA4 (AP) 104 that has decided to move the AP function to the STA2 notifies the terminal control unit 205 that the AP function is moved. The terminal control unit 205 of the STA4 (AP) 104 creates an AP function movement frame and notifies the transmission processing unit 202 to move the AP function to the STA2 102. At this time, the terminal control unit 205 extracts the terminal information in the BSS managed by the radio communication system management unit 206 and puts it in the AP function mobile frame to notify the STA2.

  STA2 waits for STA4 (AP) 104 to determine whether to move the AP function to a terminal other than STA4 or leave it as it is (step 11 in FIG. 5). Then, the AP function moving frame, which is a notification of moving the AP function from STA4 (AP) to STA2, is received (step 12 in FIG. 5). Upon receiving the AP function mobile frame, the terminal control unit 205 of the STA2 extracts terminal information in the BSS managed by the wireless communication system management unit 206 of the STA4 from the AP function mobile frame. The terminal control unit 205 passes the extracted terminal information in the BSS to the STA2 wireless communication system management unit 206 after instructing it to manage, and the own station becomes an AP and resumes the BSS (see FIG. 5 step 13).

  STA6 waits until the AP is switched and BSS can be detected (step 10 in FIG. 4). Then, the AP function moves from STA4 to STA2, and receives a Beacon from STA2 (AP) which has become a new AP (step 11 in FIG. 4). After receiving the beacon, the connection process to the new AP (STA2) is performed in the same way as the normal connection method (step 12 in FIG. 4). When notified that the connection request to the BSS is rejected via the STA2 (step 13 in FIG. 4), it abandons the connection to the BSS and requests the STA2 to relay the data communication (see FIG. 4). Step 14 of 4).

  As described above, in this embodiment, the terminal that cannot connect to the BSS because it cannot communicate with the AP relays the control frame for connecting to the BSS to the terminal in the BSS, so that the connection process to the BSS is performed. It becomes possible. Further, by investigating whether or not each terminal can communicate using the test frame, it is possible to investigate terminals that can communicate with all the terminals and select an optimum terminal that performs the AP function.

(Second Embodiment)
The present embodiment relates to a modification of the first embodiment. In this embodiment, the terminal arrangement and the relay method for connection request frames and the like by STA2 are the same as those in the first embodiment, but at least one terminal (for example, STA3 and Will explain the case where the survey results are not returned.

  When STA4 (AP) collects the survey results after transmitting the survey request frame, if the survey results from STA3 cannot be received and a certain time elapses, the survey results are compared without waiting for the survey results from STA3. Process. At this time, if the investigation results from all terminals other than STA3 indicate that communication with STA3 is not possible, it is determined that STA3 is not activated, and a disassociation frame is transmitted to STA3. After transmitting the disassociation frame, the terminal that performs the AP function is determined by the same method as in the first embodiment, based on the investigation results from terminals other than STA3. At this time, it is assumed that the terminal that performs the AP function may not be able to communicate with STA3.

  If the investigation results from all terminals other than STA3 indicate that communication with STA3 is possible, the investigation request frame is again transmitted to STA3 using a unicast address. After that, when the investigation result from STA3 can be received, the terminal that performs the AP function is determined by the same method as in the first embodiment. Alternatively, if the survey result from the STA3 cannot be received after the survey request frame is transmitted again with the unicast address, the terminal that performs the AP function is determined using the survey result of a terminal other than the STA3.

(Third embodiment)
In the present embodiment, unlike the first and second embodiments, a method for determining a terminal that performs an AP function when all terminals are sequentially activated in an environment where a BSS has not yet been constructed will be described.

  FIG. 7 shows a terminal arrangement according to the present embodiment. In the present embodiment, in a situation where the BSS has not yet been constructed, the terminals are activated in the order of STA1, STA2, STA3, STA4, STA5, and STA6. After STA1 activated first performs a scanning process for searching for a BSS, since there is no connectable BSS, its own station becomes an AP and starts the BSS. Subsequently, STA2, STA3, and STA4 to be activated connect to the BSS started by STA1 that has been activated first.

  Next, when STA5 and STA6 are activated, as shown in FIG. 7, STA5 and STA6 are outside the communication range of STA1, and therefore cannot communicate with STA1 and cannot connect to the BSS managed by STA1. Here, the STA5 transmits a connection request frame to the BSS to the STA2 as in the first embodiment. Upon receiving the connection request frame of STA5, STA2 relays this connection request frame to STA1. If STA1 that has received a connection request frame relayed by STA2 starts an investigation immediately after receiving this connection request frame, the investigation process is repeated many times if multiple such connection request frames are received. It will be. In order to prevent this, STA1 waits without starting the investigation after receiving the connection request frame until a certain time elapses after starting BSS as AP.

  When STA1 is waiting after receiving a connection request frame from STA5, STA6 is further activated. Then, since STA6 cannot communicate with STA1, STA6 transmits a connection request frame to BSS via STA3. When STA1 receives the connection request frames from STA5 and STA6, after a certain period of time has elapsed since the start of BSS, STA1 connects to the Internet of all STAs connected to BSS and the list of MAC addresses. A search request frame including a list of MAC addresses of existing STAs and MAC addresses of new STAs STA5 and STA6 is created. Then, the created survey request frame is transmitted with a broadcast address to notify all subordinate STAs.

  STA2 and STA3 that have received the survey request frame transmitted by the broadcast address relay the survey request frame to STA5 and STA6, respectively. After that, STA1 to STA6 conduct a survey using a test frame as in the first embodiment, and notify the STA1 of the survey result. At this time, STA5 and STA6 notify the investigation results via STA2 and STA3, respectively.

  The comparison method of the survey results is the same as that in the first embodiment. For example, if STA2 can communicate with all of STA1 to STA6 and the total value of the received power becomes maximum, STA1 moves the AP function to STA2. According to the present embodiment, when all terminals are sequentially activated in a situation where the BSS is not constructed, it is possible to determine an optimum terminal that performs the AP function while avoiding redundant investigation frame transmission. Can do.

(Fourth embodiment)
The present embodiment relates to a modification of the first embodiment. FIG. 8 is a diagram illustrating a terminal arrangement of the wireless communication apparatus according to the present embodiment, and FIG. 9 is a block diagram illustrating a configuration of the wireless communication apparatus according to the present embodiment.

  As shown in FIG. 9, the wireless communication device 901 of this embodiment includes a transmission processing unit 902, a reception processing unit 903, a survey unit 904, a terminal control unit 905, a wireless communication system management unit 906, and an application processing unit 907. It can operate as an STA and can also operate as an AP.

  The transmission processing unit 902 performs transmission processing of control frames such as data frames and survey request frames. The reception processing unit 903 performs reception processing of control frames such as data frames and survey request frames. The investigation unit 904 performs investigation processing by exchanging test frames. The terminal control unit 905 performs internal control of the terminal during data transmission / reception processing and control frame transmission / reception processing. The wireless communication system management unit 906 manages information of a plurality of terminals under its control when operating as an AP. The application processing unit 907 manages the operation of the application that operates on the wireless communication device, and when a stable communication band is necessary for the application to perform communication, the application processing unit 907 is an allocation request for a stable communication band. A request for a traffic stream (Traffic Stream (TS)) specified in 11e is generated.

  FIG. 10 is a message sequence chart showing the procedure of AP function movement in the wireless communication system of the present embodiment. FIG. 11 is a flowchart of the operation of the STA 6 shown in FIG. 8 newly joining the wireless communication system in the present embodiment. 12 is a flowchart of the operation of STA4 which is the initial AP. The operation of STA2 that relays a control frame between STA6 in FIG. 8 and STA4 that was an AP before joining STA6 is the same as in the first embodiment, and is used in the description of the first embodiment. Please refer to FIG.

  In the wireless communication system of this embodiment, as shown in FIG. 8, STA4 (AP) 804 is first operated as an access point, and STA1 801, STA2 802, STA3 803, STA5 805 are used as the access points of STA4 (AP) 804. A BSS (Basic Service Set) to which a total of four terminals belong is constructed and communicated (see FIG. 10). At this time, a method from when the STA6 806 outside the communication range 807 of the STA4 (AP) 804 operating as an access point starts up and belongs to the BSS will be described. When the STA6 806 belongs to the BSS, the AP function managed by the STA4 (AP) 804 is moved to the STA2 802, and the STA2 802 serves as an access point to manage the BSS. Unlike the first embodiment, since the STA1 801 that first belonged to the BSS is outside the communication range 808 of the STA2 802 that has newly become the AP, the STA1 801 is separated from the BSS that belonged to it. When the STA1 801 communicates with a terminal in the BSS, the point that the STA4 relays this is different from the first embodiment. Further, it is assumed that Traffic Stream (TS) defined by IEEE802.11e is extended between STA2-STA4, STA3-STA4, and STA5-STA4. Further, in this embodiment, as in the first embodiment, all STAs shown in FIG. 8 are wireless communication devices that can operate as either AP or STA shown in FIG. .

(4-1-1. Discovery of BSS by STA6)
When STA6 806 starts up when STA6 806 starts up when STA4 (AP) 804 and STA1 801, STA2 802, STA3 803, and STA5 805 have established a BSS (Basic Service Set) and are communicating, STA6 Performs normal scan processing. However, since STA6 is located outside the communication range 807 of the access point STA4 (AP) 804 and cannot receive a frame transmitted by the access point STA4 (AP) 804, the AP cannot be found (FIG. 11). Step 2).

  As shown in the terminal arrangement of FIG. 8, STA6 806 cannot communicate with STA4 (AP) 804, but can communicate with STA2 802. For this reason, during the scan process, the STA2 802 receives data transmitted to the STA4 (AP) 804, and thus cannot detect the AP but discovers that a BSS exists (FIG. 11). Step 3).

(4-1-2. Notification of STA6 connection request frame to STA2)
The application processing unit 907 of the STA6 806 that has discovered the BSS recognizes that a stable communication band is necessary for communication of the application used by the STA6. Thereafter, the application processing unit 907 generates a TSPEC parameter that is a parameter for setting the TS as a request of the application, and generates an ADDTS.request frame including the TSPEC parameter (step 4 in FIG. 11).

  Next, the terminal control unit 905 of the STA6 806 creates a connection request frame for requesting connection to the BSS as a connection request frame including the ADDTS.request frame generated by the application processing unit 907, and for the STA2 802, The created connection request frame is transmitted from the transmission processing unit 902 (step 5 in FIG. 11). The STA6 806 that has transmitted the connection request frame waits for a response frame to the connection request frame to be transmitted from the STA2 802 (step 6 in FIG. 11).

(4-1-3. STA2 relays connection request frame received from STA6 to AP)
Steps 1 to 4 in FIG. 5 are the same as those in the first embodiment, and a description thereof will be omitted.

(4-1-4. AP sends a survey request frame in response to a STA6 connection request)
Steps 1 to 5 in FIG. 12 are the same as steps 1 to 5 in FIG.

(4-1-5. STA2 relays survey request frame to STA6)
Steps 4 to 6 in FIG. 5 are the same as those in the first embodiment, and a description thereof will be omitted. Also, steps 6 to 8 in FIG. 11 are the same as steps 5 to 7 in FIG.

(4-1-6. Investigation by test frame)
Since the examination by the test frame is the same as 1-1-6 in the first embodiment, the description is omitted.

(4-1-7. Collection of survey results by AP)
The method for collecting the investigation results using the test frame is the same as 1-1-7 in the first embodiment, and thus the description thereof is omitted.

(4-1-8. AP function switching judgment)
In STA4 (AP) 804, the investigation result of the local station is held in the investigation unit 904 in the wireless communication apparatus 901. Thereafter, the investigation results notified from each terminal are also collected (step 7 in FIG. 12), and the investigation unit 904 determines whether or not to move the AP function to another terminal.

  The investigation unit 904 of the STA4 (AP) 804 determines from the collected investigation results whether there is a terminal that can communicate with all terminals in the BSS as in the case of the AP (step 8 in FIG. 12). At this time, if it is determined that there is a terminal that can communicate with all the terminals in the BSS as in the AP, there is a terminal that can communicate with all the terminals in the BSS and can also communicate with the STA6. Is determined (step 9 in FIG. 12). Here, when it is determined that there is a terminal that can communicate with all terminals in the BSS and can also communicate with STA6, steps 10 to 11 in FIG. 12 are performed from steps 10 to 11 in FIG. Since it is the same as that of FIG.

  If “NO” is determined in step 8 or step 9 in FIG. 12, the terminal having the maximum number of communicable terminals among the terminals that can newly communicate with the STA 6 that desires connection to the BSS is selected. Then, it is extracted as a new AP candidate terminal (step 12 in FIG. 12). At this time, if there are a plurality of terminals having the same number of communicable terminals, a plurality of new AP candidate terminals may be extracted. In the present embodiment, it is assumed that STA6 806 cannot communicate with STA1, STA3, and STA4 and STA1 801 cannot communicate with STA2, STA3, and STA6 from the survey results. In this case, only the STA4 (AP) 904 that is the current AP can communicate with all terminals in the current BSS, and step 8 in FIG. 12 is determined to be “NO”. Next, the process proceeds to step 12 where STA2 and STA5 are extracted as new AP candidate terminals as terminals having the maximum number of communicable terminals among terminals that can communicate with STA6. STA2 can communicate with a total of 4 units of STA3, STA4, STA5, and STA6, and STA5 can communicate with a total of 4 units of STA1, STA2, STA4, and STA6.

  Next, it is determined whether or not the extracted new AP candidate terminal can communicate with the terminal (step 13 in FIG. 12). A terminal to which STA2 extracted as a new AP candidate terminal cannot communicate is STA1, and a terminal to which STA5 cannot communicate is STA3. In the BSS of this embodiment, since the Traffic Stream (TS) defined by IEEE802.11e is stretched between STA2-STA4, STA3-STA4, and STA5-STA4, STA3 where TS is stretched STA5 that cannot communicate with is excluded from the new AP candidate terminals. Since STA2 cannot communicate only with STA1 to which no TS is attached, the investigation unit 904 of STA4 (AP) 804 finally selects STA2 as a new AP. At this time, if TS is not applied to STA3, the total value of the received power of STA2 and STA5 is further compared, and a terminal having a large total value is set as a new AP (step 14 in FIG. 12).

  If a TS is also applied to STA1, since the extracted new AP candidate terminal is connected to a terminal that cannot communicate with it, the AP is still set to STA4 (step 17 in FIG. 12).

(4-1-9. AP function switching)
The investigation unit 904 of the STA4 (AP) 804 that has decided to move the AP function to the STA2 notifies the terminal control unit 905 that the AP function is moved to the STA2, and that the STA2 that moves the AP function cannot communicate with the STA1. Notice. The terminal control unit 905 of STA4 (AP) 804 moves the AP function from STA4 to STA2, and STA4 relays communication with STA1 that cannot belong to BSS when the AP function is moved from STA4 to STA2. All terminals in the BSS are notified through the transmission processing unit 902 (step 15 in FIG. 12). Next, the terminal control unit 905 creates an AP function movement frame and notifies the transmission processing unit 902 to move the AP function to the STA2 802. At this time, the terminal control unit 905 extracts the terminal information in the BSS managed by the wireless communication system management unit 906, and notifies the STA2 by putting it in the AP function mobile frame.

  Steps 11 to 13 in FIG. 5 which are operations of STA2 are the same as those in the first embodiment, and thus description thereof is omitted. Further, Step 11 to Step 15 in FIG. 10 which are operations of STA6 are the same as Step 10 to Step 14 in FIG.

  At this time, connection setting information between STA1 and STA4, security encryption information, etc. can be omitted by using the information established before moving the AP function from STA4 to STA2. Can do.

  As described above, in this embodiment, the terminal that cannot connect to the BSS because it cannot communicate with the AP relays the control frame for connecting to the BSS to the terminal in the BSS, so that the connection process to the BSS is performed. It becomes possible. In addition, by using the investigation result of whether each terminal can communicate using the test frame and the setting status of the TS as information, it is possible to build a BSS consisting only of the terminal with the TS, It is possible to transmit low-priority data without a TS in a relay operation.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the terminal arrangement | positioning of the radio | wireless communications system which concerns on 1st Embodiment. 1 is a block diagram of a wireless communication apparatus according to a first embodiment. Message sequence chart showing the procedure of AP function movement in the wireless communication system according to the first embodiment Flow chart for explaining the operation of the STA 6 according to the first embodiment. Flowchart for explaining the operation of the STA2 according to the first embodiment Flow chart for explaining the operation of the STA 4 according to the first embodiment. Terminal arrangement of wireless communication system according to third embodiment The figure which shows terminal arrangement | positioning of the radio | wireless communication apparatus of 4th Embodiment. The block diagram which shows the structure of the radio | wireless communication apparatus of 4th Embodiment. Message sequence chart showing the procedure of AP function movement in the wireless communication system of the fourth embodiment Flowchart of operation of STA4 which is the initial AP in the fourth embodiment Flowchart of operation of STA 6 newly joining the wireless communication system in the fourth embodiment

Explanation of symbols

101-107 ... STA1-STA7;
210 ... wireless communication device;
202... Transmission processing unit;
203 ... reception processing unit;
204 ... Survey Department;
205 ... Terminal control unit;
206: Wireless communication system management unit

Claims (15)

A plurality of first wireless communication devices operable as a wireless base station;
Transmitting means for transmitting a survey request frame including an address of a wireless communication device to be investigated to the plurality of first wireless communication devices;
The number of terminals that each of the plurality of first wireless communication apparatuses can communicate with is obtained by transmitting a test frame toward the address by receiving the survey request frame. Receiving means for receiving a survey result representing;
A radio communication system comprising: base station selection means for selecting, as a radio base station, a first radio communication device having the largest number of communicable terminals based on the investigation result, from among the plurality of first radio communication devices. . The investigation result includes a total value of received power in each of the plurality of first wireless communication devices of a delivery confirmation response frame returned from the investigation-target wireless communication device in response to the transmission of the test frame. ,
The radio communication system according to claim 1, wherein the base station selection means selects the radio base station using the total value of the received power as a selection criterion in addition to the number of terminals capable of communication. The investigation result includes a total value of received power in each of the plurality of first wireless communication devices of the test frame transmitted from the wireless communication device to be investigated,
The radio communication system according to claim 1, wherein the base station selection means selects the radio base station using the total value of the received power as a selection criterion in addition to the number of terminals capable of communication.   The base station selection means is configured to communicate a first wireless communication apparatus having the largest number of terminals that can communicate with all terminals that can communicate with the wireless base station before transmitting the investigation request frame. The radio communication system according to claim 1, wherein a radio base station is selected from the plurality of first radio communication devices.   The base station selection means is capable of communicating with one or more first wireless communication apparatuses capable of communicating with the outside of the wireless communication system, and has the largest number of the first wireless communication apparatuses capable of communication. The radio communication system according to claim 1, wherein a communication device is selected as a radio base station from the plurality of first radio communication devices.   The first radio communication device having the largest number of the first radio communication devices for which a communicable traffic stream is set in the base station selection means is defined as a radio base station from among the plurality of first radio communication devices. The wireless communication system according to claim 1 to be selected.   The second wireless communication device receives the connection request frame from the second wireless communication device that requests connection to the wireless base station, the investigation request frame from the wireless base station, and the investigation target frame. Obtained by transmitting a test frame toward the address of the communication device and relaying a result indicating the number of terminals that can be communicated by the second wireless communication device between the second wireless communication device and the wireless base station The wireless communication system according to claim 1, further comprising a third wireless communication device. Transmitting means for transmitting a survey request frame including an address of a radio communication device to be investigated to a plurality of first radio communication devices operable as a radio base station;
The number of terminals that each of the plurality of first wireless communication apparatuses can communicate with is obtained by transmitting a test frame toward the address by receiving the survey request frame. Receiving means for receiving a survey result representing;
Selection means for selecting, from the plurality of first wireless communication devices, a first wireless communication device having the largest number of terminals capable of communication based on the investigation result;
And a control unit that performs control so that the selected first radio communication device starts operation as a radio base station. The investigation result includes a total value of received power in each of the plurality of first wireless communication devices of a delivery confirmation response frame returned from the investigation-target wireless communication device in response to the transmission of the test frame. ,
9. The wireless communication apparatus according to claim 8, wherein the selection unit uses the total value of the received power as a reference for selecting the first wireless communication apparatus in addition to the number of terminals capable of communication. The investigation result includes a total value of received power in each of the plurality of first wireless communication devices of the test frame transmitted from the wireless communication device to be investigated,
9. The wireless communication apparatus according to claim 8, wherein the selection unit uses the total value of the received power as a reference for selecting the first wireless communication apparatus in addition to the number of terminals capable of communication.   The selecting means is configured to communicate the plurality of first wireless communication devices with the largest number of terminals that can communicate with all terminals that can communicate with the wireless base station before transmitting the investigation request frame. The wireless communication device according to claim 8, wherein the wireless communication device is selected from the first wireless communication devices.   The selection means is capable of communicating with one or more of the first wireless communication devices capable of communicating with the outside of the wireless communication system, and has the largest number of the first wireless communication devices capable of communication. The wireless communication device according to claim 8, wherein the wireless communication device is selected from the plurality of first wireless communication devices.   The selection means selects a first wireless communication device having the largest number of the first wireless communication devices that are setting a communicable traffic stream from the plurality of first wireless communication devices. The wireless communication apparatus according to claim 8. Means for relaying, to the radio base station, a connection request frame transmitted from the first radio communication apparatus that cannot directly communicate with the radio base station and requesting connection to the radio base station;
A survey request frame transmitted from the radio base station in response to the connection request frame and including an address of a second radio communication device to be surveyed, which requests a survey of information used for switching determination of the radio base station. Means for relaying to one wireless communication device;
A survey representing the number of terminals that can be communicated by the first wireless communication device, which is obtained when the first wireless communication device transmits a test frame toward the address of the second wireless communication device by receiving the survey request frame. Means for relaying a result to the wireless base station. Means for confirming the presence of the wireless communication system by receiving a frame exchange performed by the first wireless communication device with the wireless base station or another first wireless communication device;
Means for transmitting a connection request frame to the radio communication system to the first radio communication apparatus so as to relay the connection request frame from the first radio communication apparatus to the radio base station;
A survey request frame transmitted from the radio base station in response to the connection request frame and including an address of a first radio communication device to be surveyed, and requesting a survey of information used for switching determination of the radio base station, Means for recognizing that a connection request to the wireless communication system has been accepted by the wireless base station by being relayed from one wireless communication device and receiving the relayed connection request frame;
Upon receiving the survey request frame, a survey result obtained by transmitting a test frame toward the address of the first wireless communication device and indicating the number of communicable terminals is sent from the first wireless communication device to the wireless base station. Means for transmitting to the first wireless communication device so as to relay to the station.

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