JP5509989B2 - Radio relay apparatus and radio communication method in radio communication system - Google Patents

Description

  The present invention relates to a wireless communication system that performs wireless communication via a relay station, and more particularly to a wireless relay device and a wireless communication method used in such a wireless communication system.

  Currently, communication between a wireless communication terminal possessed by each client (hereinafter referred to as a client terminal) and a base station that provides various information to each client terminal is performed via a moving wireless relay station. A mobile radio communication system has been proposed (see, for example, FIG. 1 of Patent Document 1).

  In such a mobile radio communication system, a radio relay station is mounted on a plurality of mobile bodies (vehicles, etc.) and moved, and information data received from a base station is relayed to a client terminal by the moving radio relay station. At the same time, information data from the client terminal side is wirelessly relayed to the base station side. Here, in the above mobile radio communication system, when communication is established between the client terminal and the radio relay station, if this radio relay station moves to an area outside the relay range, it is automatically Switch to other wireless relay stations.

  However, when switching a wireless relay station that has become incapable of relaying to another wireless relay station, the connection switching may fail.

JP 2004-297445 A

  The present invention has been made to solve such a problem, and a radio relay apparatus in a radio communication system capable of suppressing a connection failure at the time of relay station switching when communication with a base station is interrupted, and An object is to provide a wireless communication method.

A radio relay apparatus in a radio communication system according to the present invention is a radio relay apparatus in a radio communication system that performs radio communication between a plurality of communication terminals and a base station via a plurality of radio relay apparatuses, and the other radio relay apparatus A first wireless transmission / reception unit responsible for communication with the device, a second wireless transmission / reception unit responsible for communication with the communication terminal, and a third wireless transmission / reception unit responsible for communication with the base station And when the communication state with the base station is in a good state, the second and third wireless transmission / reception units perform communication between the communication terminal and the base station, When the communication between the wireless relay devices is interrupted by the first wireless transmission / reception unit, the first wireless transmission / reception unit establishes communication with one wireless relay device in each of the neighboring wireless relay devices. The base station via a wireless relay device Possess a communication control unit for controlling the first and second radio transceiver in order to perform communication and between, the, the communication control unit, said near the by the ad hoc mode of the IEEE802.11 wireless LAN radio A first means for detecting each of the wireless relay devices in a communicable state from within each of the relay devices, and a state in which communication is possible from within each of the peripheral wireless relay devices by the IEEE802.11 wireless LAN infrastructure mode A second means for detecting each of the wireless relay devices, and the number of the wireless relay devices detected by the first means is greater than the number of the wireless relay devices detected by the second means The first wireless relay device is selected from each of the wireless relay devices detected by the ad hoc mode, while being detected by the second means. When the number of the wireless relay devices detected is larger than the number of the wireless relay devices detected by the first means, the one wireless relay device among each of the wireless relay devices detected by the infrastructure mode And a third means for selecting .

The wireless communication method according to the present invention is a wireless communication method for performing wireless communication between a plurality of communication terminals and a base station via a plurality of wireless relay devices, and the base station within each of the wireless relay devices. In a wireless relay device in which communication with a station is in a good state, a first wireless transmission / reception unit that is responsible for communication with another wireless relay device, and a second wireless that is responsible for communication with the communication terminal The wireless relay device performs communication between the communication terminal and the base station by the second and third wireless transmission / reception units of a third wireless transmission / reception unit responsible for communication between the transmission / reception unit and the base station. In each of the wireless relay devices in which communication with the base station is interrupted in each of the wireless relay devices, the first wireless transmission / reception unit connects the wireless relay device to one of the neighboring wireless relay devices. By establishing communication, the one wireless relay device is Per a manner communicating between the base station detects a respective radio relay apparatus in a communicable state from among the radio relay apparatus each near said by the ad hoc mode of the IEEE802.11 wireless LAN, and Each of the wireless relay devices in a communicable state is detected from each of the neighboring wireless relay devices by the IEEE 802.11 wireless LAN infrastructure mode, and the number of the wireless relay devices detected by the ad hoc mode is determined. When the number of wireless relay devices detected by the infrastructure mode is larger than the number of wireless relay devices detected by the ad hoc mode, the one wireless relay device is selected from each of the wireless relay devices detected by the ad hoc mode. The number of detected wireless relay devices is If there are more than the number of the wireless relay devices detected by the ad hoc mode, the one wireless relay device is selected from each of the wireless relay devices detected by the infrastructure mode .

  In the present invention, a first wireless transmission / reception unit for performing communication between wireless relay devices, a second wireless transmission / reception unit for performing communication with a communication terminal, and a third wireless for performing communication with a base station When the communication state between the radio relay apparatus including the transmission / reception unit and the base station is good, communication between the communication terminal and the base station is performed via the second and third radio transmission / reception units. Here, when the communication between the wireless relay device and the base station is cut off, the first wireless transmission / reception unit mounted on the wireless relay device in which the communication is cut off causes each of the surrounding wireless relay devices to By establishing communication with the one wireless relay device, the wireless relay device is relayed to maintain the connection with the base station. At this time, the communication between the wireless relay devices performed when the communication is interrupted is performed by the first wireless transmission / reception unit provided separately from the second wireless transmission / reception unit responsible for communication with the communication terminal. It becomes possible to suppress a connection failure when switching the wireless relay device responsible for communication to another wireless relay device.

It is a figure which shows the outline | summary of the radio | wireless communications system containing the radio relay apparatus by this invention. It is a figure which shows the structure of the communication process part contained in the WiFi terminal 2 shown by FIG. It is a figure which shows the structure of the communication process part contained in the WiMAX base station 3 shown by FIG. It is a figure which shows the internal structure of the WiFi-WiMAX gateway 1 shown by FIG. It is a figure which shows an example of a data transmission destination list. It is a figure which shows an example of the communication operation | movement in [normal communication mode]. It is a figure which shows a 1st relay transfer process routine. It is a figure which shows a 2nd relay transfer process routine. It is a figure which shows an example of the communication operation in [relay transfer mode]. It is a figure which shows the surrounding gateway detection processing routine implemented in the data transmission destination control part, when detecting the surrounding gateway 1 using an ad hoc mode and an infrastructure mode.

  In the present invention, in a wireless communication system that performs wireless communication between a plurality of communication terminals and a base station via a plurality of wireless relay devices, each wireless relay device is responsible for communication between the wireless relay devices. A first wireless transmission / reception unit, a second wireless transmission / reception unit responsible for communication with the communication terminal, and a third wireless transmission / reception unit responsible for communication with the base station are provided. When the communication state between the radio relay apparatus and the base station is good, communication between the communication terminal and the base station is performed via the second and third radio transmission / reception units in the radio relay apparatus. Here, when the communication between the wireless relay device and the base station is interrupted, one of each of the peripheral wireless relay devices is detected by the first wireless transmission / reception unit mounted on the wireless relay device in the communication disconnected state. By establishing communication with the other wireless relay device, this one wireless relay device is relayed to establish a connection with the base station.

  FIG. 1 is a diagram showing an outline of a wireless communication system including a wireless relay device according to the present invention.

As shown in FIG. 1, such a mobile radio communication system includes a WiFi-WiMAX gateway 1 _{1 to} 1n (n is an integer of 2 or more) as a wireless neutral device, and a WiFi terminal 2 as a client-side communication terminal. _{1 to} 2 m (m is an integer of 2 or more) and a WiMAX base station 3 as a base station.

Each of the WiFi terminals 2 _{1 to} 2 m owned by each user communicates with IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 802.11 with one of the WiFi-WiMAX gateways 1 _{1 to 1} n. Wireless communication based on a compliant wireless network protocol (hereinafter referred to as WiFi standard) is performed. WiFi is a registered trademark.

FIG. 2 is a diagram illustrating a configuration of a communication processing unit that is commonly included in each of the WiFi terminals 2 _{1 to} 2 m.

  In FIG. 2, a wireless transmission unit 21 wirelessly transmits a wireless signal (hereinafter referred to as a WiFi signal) obtained by modulating information data to be transmitted based on the WiFi standard to a WiFi-WiMAX gateway 1 (hereinafter simply referred to as a gateway 1). Send. The wireless reception unit 22 receives the WiFi signal transmitted from the gateway 1 and restores the information data from the received WiFi signal. The wireless control unit 23 performs various transmission / reception controls for the wireless transmission unit 21 and the wireless reception unit 22.

The WiMAX base station 3 performs wireless communication with each of the gateways 1 _{1 to} 1n based on the WiMAX (World interoperability for microwave access) standard compliant with IEEE 802.16e that supports a communication area wider than WiFi. WiMAX is a registered trademark.

  FIG. 3 is a diagram illustrating a configuration of a communication processing unit included in the WiMAX base station 3.

In FIG. 3, a wireless transmission unit 31 wirelessly transmits a wireless signal obtained by modulating information data to be transmitted based on the WiMAX standard (hereinafter referred to as a WiMAX signal) to one of the gateways 1 _{1 to} 1n. When receiving the WiMAX signal transmitted from the gateway 1, the wireless reception unit 32 restores the information data from the received WiMAX signal. The wireless control unit 33 performs various transmission / reception controls for the wireless transmission unit 31 and the wireless reception unit 32.

Each of the gateways 1 1 to ₁ n is mounted on a mobile body such as a vehicle, and relays wireless communication between the WiFi terminals 2 _{1 to} 2 m and the WiMAX base station 3.

FIG. 4 is a diagram illustrating a configuration of a communication processing unit that is commonly included in each of the gateways 1 1 to ₁ n.

  As shown in FIG. 4, each gateway 1 includes a first WiFi wireless LAN (Local Area Network) unit F1 including a WiFi receiving unit 101 and a WiFi transmitting unit 102, and a second WiFi including a WiFi receiving unit 103 and a WiFi transmitting unit 104. A wireless LAN unit F2 is included. Furthermore, each gateway 1 includes a WiFi control unit CNT, a WiFi-WiMAX conversion unit 107, a WiMAX control unit 108, a WiMAX wireless transmission / reception unit MX, and a data transmission destination list memory 111. The WiFi control unit CNT includes a data transmission destination control unit 105 and a WiFi connection control unit 106. The WiMAX wireless transmission / reception unit MX includes a WiMAX reception unit 109 and a WiMAX transmission unit 110.

In FIG. 4, the WiFi receiving unit 101 of the first WiFi wireless LAN unit F1 receives the WiFi signal wirelessly transmitted from the gateway 1 or the WiFi terminal 2, and uses the WiFi signal as the received WiFi signal WF1 _R , and the WiFi control unit CNT and WiFi- The data is supplied to the WiMAX conversion unit 107. WiFi transmitter 102 of the 1WiFi wireless LAN unit F1 is converted WiFi signal WF _T supplied from WiFi-WiMAX converter 107 as WiFi signals, wirelessly transmitted to the gateway 1 or WiFi terminal 2.

The WiFi receiving unit 103 of the second WiFi wireless LAN unit F2 receives the WiFi signal wirelessly transmitted from the gateway 1 or the WiFi terminal 2, and uses the WiFi signal as the received WiFi signal WF2 _R , and the WiFi control unit CNT and the WiFi-WiMAX conversion unit. 107 is supplied. WiFi transmitter 104 of the 2WiFi wireless LAN unit F2 is converted WiFi signal WF _T supplied from WiFi-WiMAX converter 107 as WiFi signals, wirelessly transmitted to the gateway 1 or WiFi terminal 2.

  The data transmission destination control unit 105 of the WiFi control unit CNT performs peripheral gateway detection control on the first WiFi wireless LAN unit F1 in order to detect the peripheral gateway 1 that can communicate with the gateway 1. With this peripheral gateway detection control, the first WiFi wireless LAN unit F1 first wirelessly transmits a WiFi signal representing a communication availability request command to notify each gateway 1 except this gateway whether or not communication is possible. Send. At this time, the gateway 1 that has been able to receive the WiFi signal indicating the communication availability request command returns a WiFi signal indicating that communication is possible to the gateway. The data transmission destination control unit 105 of this gateway determines “communication is possible” for the gateway 1 that has returned a WiFi signal indicating that communication is possible based on the return result from each gateway, and does not return to the gateway 1 that has not returned. Communication enable / disable information is generated that associates “communication disabled” with each other. Then, the data transmission destination control unit 105 stores a data transmission destination list as shown in FIG. 5 in which the communication availability information is associated with the SSID (Service Set Identifier) of each gateway 1 in the data transmission destination list memory 111. Write.

  In addition, the data transmission destination control unit 105 responds to a command from the WiFi connection control unit 106 and selects a relay candidate (described later) from the data transmission destination list as shown in FIG. 5 stored in the data transmission destination list memory 111. The SSID of the gateway 1 is read out and supplied to the WiFi connection control unit 106. Further, the data transmission destination control unit 105 rewrites the contents of the data transmission destination list stored in the data transmission destination list memory 111 in response to a command from the WiFi connection control unit 106.

  The WiFi connection control unit 106 of the WiFi control unit CNT performs various communication connection controls (described later) for each of the first WiFi wireless LAN unit F1 and the second WiFi wireless LAN unit F2.

WiFi-WiMAX conversion unit 107, a first 1WiFi wireless LAN unit F1 or the 2WiFi wireless LAN unit received WiFi signal WF1 supplied from F2 _R or WF2 _R, the conversion WiMAX signal WM _T having a signal form that conforms to the WiMAX standard This is converted and supplied to the WiMAX wireless transmission / reception unit MX. Further, WiFi-WiMAX conversion unit 107, the received WiMAX signals WM _R supplied from such WiMAX wireless transceiver MX, into a converted WiFi signal WF _T having a signal form that conforms to the WiFi standard, a 1WiFi wireless it The data is supplied to the LAN unit F1 and the second WiFi wireless LAN unit F2.

The WiMAX wireless transmission / reception unit MX includes a WiMAX reception unit 109 and a WiMAX transmission unit 110. WiMAX receiver 109 receives a WiMAX signal wirelessly transmitted from the WiMAX base station 3 shown in FIG. 1, and supplies the WiFi-WiMAX converter 107 it as the received WiMAX signal WM _R. WiMAX transmission unit 110, a conversion WiMAX signal WM _T supplied from WiFi-WiMAX converter 107 as WiMAX signals, wirelessly transmitted to the WiMAX base station 3. The WiMAX control unit 108 performs various communication connection controls for the WiMAX wireless transmission / reception unit MX. At this time, the WiMAX control unit 108 supplies communication status information TQ indicating whether the WiMAX wireless transmission / reception unit MX and the WiMAX base station 3 are in a communication connection state or a communication cutoff state to the WiFi control unit CNT.

Hereinafter, an operation in [normal communication mode] performed in the mobile radio communication system having the above-described configuration, that is, a communication operation when the communication state is good will be described with reference to a communication flow shown in FIG. In FIG. 6, in which the gateway _{1 1} will be described the operation for an example a case of performing relay communications between the WiFi terminal _{2 1} and WiMAX base station 3.

First, when the user requests acquisition of a desired information data by operating the WiFi terminal _{2 1} itself possessed, WiFi terminal _{2 1,} a WiFi signal representing a request for the information data, to the gateway _{1 1} The wireless transmission is performed (S1). At this time, the 2WiFi wireless LAN unit F2 of the two WiFi wireless transceiver unit provided in the gateway _{1 1} (F1, F2) are to receive the radio transmitted WiFi signal from the WiFi terminal _{2 1.} Thus, the gateway _{1 1,} a WiFi signal representing a request for acquisition of desired information data such as described above, converts the WiMAX signal, which is wirelessly transmitted to the WiMAX base station 3 (S2). The WiMAX base station 3 acquires the information data requested to be acquired by the received WiMAX signal via a communication network such as the Internet (not shown), and receives the WiMAX signal representing this information data from the requesting gateway 1 _1. Wirelessly transmitted to the terminal (S3). The gateway _{1 1} receives such a WiMAX signal, converts the WiMAX signal to a WiFi signal. Then, the 2WiFi wireless LAN unit F2 gateway _{1 1} wirelessly transmits the WiFi terminal _{2 first} requesting it (S4). WiFi terminal _{2 1} receives such a WiFi signal, to restore the desired information data by performing demodulation processing on the WiFi signal (S5).

Thus, a series of communication operations consisting Step S1~S5 shown in FIG. 6, WiFi terminals _{2 1,} via the gateway _{1 1,} it is possible to obtain the desired information data from the WiMAX base station 3 . In this case, the gateway _{1 1,} the transmission and reception of the WiFi signals between the WiFi terminal _{2 1,} so as to perform in the way of the 2WiFi wireless LAN unit F2 of the two WiFi wireless transceiver (F1, F2) Yes. That is, when the communication state is good, the gateway 1 communicates with the WiFi terminal 2 using the second WiFi wireless LAN unit F2 to perform the relay between the WiFi terminal 2 and the WiMAX base station 3 [normally] [Communication mode].

  By the way, since the gateway 1 is mounted on a moving body such as a vehicle, when the gateway 1 itself moves out of the communication range of the WiMAX base station 3, the communication is interrupted. Therefore, even if communication between the WiFi terminal 2 and the gateway 1 is normally performed, communication between the WiFi terminal 2 and the WiMAX base station 3 is not established. However, according to the gateway 1 of the mobile radio communication system shown in FIG. 1, even when such communication interruption occurs, it is possible to continue relaying between the WiFi terminal 2 and the WiMAX base station 3.

  FIG. 7 shows the process executed by the WiFi control unit CNT when communication state information TQ indicating communication cutoff is supplied from the WiMAX control unit 108, that is, when communication between the WiMAX wireless transmission / reception unit MX and the WiMAX base station 3 is cut off. It is a figure which shows the 1st relay transfer process routine performed.

  In FIG. 7, the WiFi control unit CNT first selects one of the SSIDs from the data transmission destination list stored in the data transmission destination list memory 111 as shown in FIG. 5, and the gateway corresponding to the selected SSID. 1 is a relay candidate. Then, the WiFi control unit CNT supplies the first WiFi wireless LAN unit F1 with a connection request command for establishing communication with the gateway 1 serving as the relay candidate (step S202). Thus, the first WiFi wireless LAN unit F1 wirelessly transmits a WiFi signal representing a connection request to the gateway 1 that is a relay candidate.

  Next, the WiFi control unit CNT supplies to the first WiFi wireless LAN unit F1 a communication enable / disable request command to notify the relay candidate gateway 1 as described above of whether or not communication is possible (step S203). . As a result, the first WiFi wireless LAN unit F1 wirelessly transmits a WiFi signal representing a communication availability request to the gateway 1 as a relay candidate.

Next, based on the received WiFi signal WF1 _R supplied from the first WiFi wireless LAN unit F1, the WiFi control unit CNT determines whether the response result returned from the relay candidate gateway 1 is a communicable response indicating that communication is possible. It is determined whether or not (step S204). If it is determined in step S204 that the response is not a communicable response, that is, if it is determined that the response is a communication disabling response indicating that communication is not possible, the WiFi control unit CNT displays the relay candidate gateway 1 on the data transmission destination list. The contents of the data transmission destination list memory 111 are updated so that the communication enable / disable information associated with the SSID is “communication disabled” (step S205). After the execution of step S205, the WiFi control unit CNT returns to the execution of step S202 and repeatedly executes the operation as described above. That is, in the data transmission destination list, another gateway 1 different from the previous relay candidate is set as a new relay candidate, and the series of processes of steps S202 to S204 are executed again.

During this time, if it is determined in step S204 that the communication candidate response indicating that communication is possible is made from the relay candidate gateway 1, the WiFi control unit CNT sets the relay candidate gateway 1 as the relay gateway. . Then, the WiFi control unit CNT updates the contents of the data transmission destination list memory 111 so that the communication availability information associated with the SSID of the relay gateway is “communicable” on the data transmission destination list. Then, a process to switch the [normal communication mode] as described above to the [relay transfer mode] as follows (step S206). That is, in the [relay transfer mode], the WiFi control unit CNT causes the first WiFi wireless LAN unit F1 to wirelessly transmit the received WiFi signal WF2 _R received by the second WiFi wireless LAN unit F2 to the relay gateway, and also performs the first WiFi wireless communication. The first WiFi wireless LAN unit F1 and the second WiFi wireless LAN unit F2 are set so that the received WiFi signal WF1 _R received by the LAN unit F1 is wirelessly transmitted to the WiFi terminal 2 by the second WiFi wireless LAN unit F2. Therefore, in the [relay transfer mode], the gateway 1 transfers the WiFi signal transmitted from the WiFi terminal 2 to the relay gateway, while transmitting the WiFi signal transmitted from the relay gateway to the WiFi terminal 2.

  Next, the WiFi control unit CNT recovers whether or not the communication state information TQ indicates a communication connection state, that is, whether or not communication between the WiMAX wireless transmission / reception unit MX and the WiMAX base station 3 has been recovered. The process is repeated until it is determined that it has been performed (step S207). If it is determined in step S207 that communication has been restored, the WiFi control unit CNT should switch [relay transfer mode] to [normal communication mode] for the first WiFi wireless LAN unit F1 and the second WiFi wireless LAN unit F2. In addition to the setting, a relay transfer end command to end the [relay transfer mode] to the relay gateway is supplied to the first WiFi wireless LAN unit F1 (step S208). As a result, the first WiFi wireless LAN unit F1 wirelessly transmits a WiFi signal representing a relay transfer end command to end the [relay transfer mode] to the relay gateway.

  After execution of step S208, the WiFi control unit CNT exits from the first relay transfer processing routine and returns to the execution of the main routine (not described).

FIG. 8 is a diagram showing a second relay transfer processing routine periodically executed in the WiFi control unit CNT of each of the gateways 1 _{1 to} 1n.

In FIG. 8, first, the WiFi control unit CNT determines whether or not the received WiFi signal WF2 _R supplied from the second WiFi wireless LAN unit F2 is a WiFi signal representing a connection request from another gateway 1. (Step S102). If it is determined in step S102 that the received WiFi signal WF2 _R is not a WiFi signal indicating a connection request, the WiFi control unit CNT exits the second relay transfer processing routine and executes the main routine (not described). Return. On the other hand, when it is determined in step S102 that the received WiFi signal WF2 _R is a WiFi signal indicating a connection request, the WiFi control unit CNT becomes a connection request transmission source for the second WiFi wireless LAN unit F2. Communication connection setting for establishing connection with the gateway 1 is performed (step S103). By executing step S103, the second WiFi wireless LAN unit F2 is set to a state in which transmission / reception with respect to the gateway 1 that is the transmission source of the connection request is performed together with transmission / reception with respect to the WiFi terminal 2 having already established communication connection.

Next, the WiFi control unit CNT determines that it has received a determination as to whether or not it has received a WiFi signal representing a communication permission request based on the received WiFi signal WF2 _R supplied from the second WiFi wireless LAN unit F2. Are repeatedly executed (step S104). If it is determined in step S104 that the WiFi signal indicating the communication availability request has been received, the WiFi control unit CNT determines whether communication with the gateway 1 that is the source of the connection request is possible. Is determined (step S105). If it is determined in step S105 that communication with the connection request source gateway 1 is not possible, the WiFi control unit CNT cannot transmit a communication disable response to the source gateway 1. A response command is supplied to the second WiFi wireless LAN unit F2 (step S106). As a result, the second WiFi wireless LAN unit F2 wirelessly transmits a WiFi signal indicating a communication failure response to the gateway 1 that is the connection request transmission source. After execution of step S106, the WiFi control unit CNT exits from the second relay transfer processing routine and returns to execution of the main routine (not described).

  On the other hand, if it is determined in step S105 that communication with the connection request transmission source gateway 1 is possible, the WiFi control unit CNT can communicate with the transmission source gateway 1. A communicable response command for transmitting a response is supplied to the second WiFi wireless LAN unit F2 (step S107). As a result, the second WiFi wireless LAN unit F2 wirelessly transmits a WiFi signal representing a communicable response to the gateway 1 that is the transmission source of the connection request.

  By executing the above steps S103 to S107, the gateway 1 enters an operation state according to the [relay transfer mode]. That is, according to the [relay transfer mode], the gateway 1 together with the WiFi signal transmitted from the gateway 1 that is the connection request transmission source, together with the WiFi representing the information data transmitted from the WiFi terminal 2 that is already connected. The second WiFi wireless LAN unit F2 receives the signal, converts each signal into a WiMAX signal, and wirelessly transmits it to the WiMAX base station 3. Also, the gateway 1 converts the WiMAX signal transmitted from the WiMAX base station 3 into a WiFi signal to be transferred to the gateway 1 that is a connection request transmission source and a WiFi signal to be transmitted to the WiFi terminal 2. . Then, the WiFi signal to be transferred to the gateway 1 that is the connection request transmission source is wirelessly transmitted to the gateway 1 that is the connection request transmission source and transmitted to the WiFi terminal 2 by the second WiFi wireless LAN unit F2. The WiFi signal to be transmitted is wirelessly transmitted to each WiFi terminal 2 by the second WiFi wireless LAN unit F2.

After execution of step S107, the WiFi control unit CNT has received a determination as to whether or not a WiFi signal representing a relay transfer end command has been received based on the received WiFi signal WF2 _R supplied from the second WiFi wireless LAN unit F2. The process is repeatedly executed until it is determined (step S108). If it is determined in step S108 that the WiFi signal representing the relay transfer end instruction has been received, the WiFi control unit CNT performs the setting for releasing the communication with the gateway 1 that is the transmission source of the connection request described above in the second WiFi wireless LAN unit. It applies to F2 (step S109). By executing step S109, the WiFi control unit CNT is in a state of performing only transmission / reception with respect to the WiFi terminal 2 for which communication connection has already been established.

  After execution of step S109, the WiFi control unit CNT exits from the second relay transfer processing routine and returns to the execution of the main routine (not described).

  Hereinafter, the communication operation performed by the execution of the first and second relay transfer processing routines shown in FIGS. 7 and 8, that is, the gateway 1 is executing the relay between the WiFi terminal 2 and the WiMAX base station 3. A relay transfer operation performed when communication with the WiMAX base station 3 is interrupted will be described with reference to an example of FIG.

Incidentally, FIG. 9, at [normal communication mode, the gateway _{1 1} as shown in FIG. 1 performs relaying between the WiFi terminal _{2 1} and _{2 2} respectively and WiMAX base station 3, the gateway _{1 2} WiFi terminal when doing relay between 2 ₃ and WiMAX base station 3, illustrates a communication operation by the communication between the gateway 1 ₁ and WiMAX base station 3 is made in the case of blocking.

9, when the communication between the gateway 1 ₁ and WiMAX base station 3 is cut off, the gateway 1 ₁ first elected gateway 1 ₂ as the gateway relay candidate from such data transmission destination in the list shown in FIG. 5, this the gateway _{1 2} to transmit the WiFi signal indicating a connection should be established a communication request by the 1WiFi wireless LAN unit F1 (S202). A WiFi signal representative of the connection request gateway _{1 2} received by the 2WiFi wireless LAN unit F2 performs to be established communication connection set up communication with the gateway _{1 1} source (S103).

Thereafter, the gateway _{1 1,} to the gateway _{1 2} to transmit the WiFi signal representing a communication state whether the notified communication enabling request should be the in the first 1WiFi wireless LAN unit F1 (S203).

Gateway _{1 2} receives the WiFi signal representing this communication enabling request by the 2WiFi wireless LAN unit F2, when together with the communication to the WiFi terminal _{2 3} itself is responsible for relaying, can communicate to the gateway _{1 1,} A WiFi signal representing a communicable response is transmitted by the first WiFi wireless LAN unit F1 (S107). The gateway _{11 that} has received the WiFi signal representing the communicable response by the first WiFi wireless LAN unit F1 switches from the [normal communication mode] to the [relay transfer mode] operation state (S206).

That is, in the Relay Transfer Mode, the gateway _{1 1,} as shown in FIG. 9 receives the WiFi signal transmitted from each of the WiFi terminal _{2 1} and _{2 2} in the first 2WiFi wireless LAN unit F2, these by the 1WiFi wireless LAN unit F1 is transferred to the gateway _{1 2} as a relay gateway. At this time, the relay gateways _{1 2,} together with the WiFi signal transmitted from the WiFi terminal _{2 3,} WiFi signal transferred from the gateway _{1 1,} i.e. a WiFi signal transmitted from the WiFi terminal _{2 1} and _{2 2} respectively Each of them is individually converted into a WiMAX signal and wirelessly transmitted to the WiMAX base station 3.

Further, the Relay Transfer Mode, the gateway _{1 2} as a relay gateway, as shown in FIG. 9, transmitted from WiMAX base station 3, a WiMAX signal towards ₂ 1 to 2 _3, respectively WiFi terminal The second WiFi wireless LAN unit F2 receives the signals and converts them into WiFi signals. Then, the gateway _{1 2} a WiFi signal corresponding to the WiFi terminal _{2 3} of the converted WiFi signals respectively by the 2WiFi wireless LAN unit F2 with wirelessly transmitted to the WiFi terminal _{2 3,} WiFi terminal _{2 1} and 2 each of the WiFi signal corresponding to ₂ by the 2WiFi wireless LAN unit F2 transferred to the gateway _{1 1.} In this case, the gateway _{1 1,} has been transferred from the gateway _{1 2} receives each of the WiFi terminal _{2 1} and _{2 2} WiFi signal corresponding to the first 1WiFi wireless LAN unit F1, these first 2WiFi wireless LAN unit F2 To wirelessly transmit to the WiFi terminals 2 ₁ and 2 ₂ respectively.

Thus, the Relay Transfer Mode, if the communication between the gateway 1 ₁ and WiMAX base station 3 is cut off, the periphery of the gateway 1 _{2 (relay} gateway in communication state capable of WiMAX base station 3 ) by way of, so that to realize the communication between the gateway 1 ₁ and WiMAX base station 3. At this time, each gateway 1 includes, in addition to the second WiFi wireless LAN unit F2 that performs communication with the WiFi terminal 2, a first WiFi wireless LAN unit that performs relay transfer between the gateways 1 in the [relay transfer mode]. F1 is mounted. Therefore, even when switching from [normal communication mode] to [relay transfer mode], it is possible to perform relay transfer between each gateway 1 without interrupting communication with the WiFi terminal 2. . Therefore, it is possible to suppress a connection failure when the relay station (gateway 1) responsible for relaying between the WiFi terminal 2 and the WiMAX base station 3 is switched to another relay station.

  In the above embodiment, in order to create a data destination list as shown in FIG. 5, the peripheral gateway detection processing performed in the data destination control unit 105 is an ad hoc mode which is an IEEE 802.11 wireless LAN operation mode. And the infrastructure mode may be used.

  FIG. 10 is a diagram illustrating a peripheral gateway detection processing routine that is performed in the data transmission destination control unit 105 when the peripheral gateway 1 that can communicate using these ad hoc mode and infrastructure mode is detected.

  In FIG. 10, first, the data transmission destination control unit 105 detects peripheral gateways 1 that can communicate with each other in the ad hoc mode (step S91). Next, the data transmission destination control unit 105 detects peripheral gateways 1 that can communicate with each other in the infrastructure mode (step S92). Next, the data transmission destination control unit 105 determines whether or not the number N1 of the peripheral gateways 1 detected by the above-described ad hoc mode is larger than the number N2 of the peripheral gateways 1 detected by the infrastructure mode. (Step S93). In step S93, when it is determined that the number N1 of the peripheral gateways 1 detected in the ad hoc mode is larger, the data transmission destination control unit 105 “communication is possible” to each of the peripheral gateways 1 detected in the ad hoc mode. A data transmission destination list is generated by associating communication enable / disable information representing the information (step S94). On the other hand, if it is determined in step S93 that the number N2 of peripheral gateways 1 detected in the infrastructure mode is larger, the data transmission destination control unit 105 determines that the peripheral gateway 1 detected in the infrastructure mode. A data transmission destination list is generated by associating communication enable / disable information indicating “communication enabled” with each (step S95). After executing step S94 or S95, the data transmission destination control unit 105 stores the data transmission destination list in the data transmission destination list memory 111 (step S96).

  As described above, in the peripheral gateway detection processing using the ad hoc mode and the infrastructure mode, first, the peripheral gateways 1 that can communicate with each other in both modes are detected. Then, a data transmission destination in which communication enable / disable information indicating “communication enabled” is associated with each of the peripheral gateways 1 detected in the mode with the larger number of detected gateways 1 in the ad hoc mode and the infrastructure mode. A list is generated. As a result, the relay candidates as described above are selected from the number of gateways 1 detected in the ad hoc mode and the gateways 1 detected in the larger one of the number of gateways 1 detected in the infrastructure mode. Gateway 1 is selected.

1 ₁ to 1 _n WiFi-WiMAX gateway 2 ₁ to 2 _m WiFi terminal 3 WiMAX base station CNT WiFi control unit F1 1st WiFi wireless LAN unit F2 2nd WiFi wireless LAN unit

Claims (2)

A wireless relay device in a wireless communication system that performs wireless communication between a plurality of communication terminals and a base station via a plurality of wireless relay devices,
A first wireless transmission / reception unit responsible for communication with another wireless relay device;
A second wireless transmission / reception unit responsible for communication with the communication terminal;
A third wireless transmission / reception unit responsible for communication with the base station;
When the communication state with the base station is in a good state, the communication between the communication terminal and the base station is performed by the second and third wireless transmission / reception units, while the communication with the base station is performed. When the communication is cut off, the first wireless transmission / reception unit establishes communication with one wireless relay device in each of the neighboring wireless relay devices, thereby the first wireless relay unit. through the device have a, a communication control unit for controlling the first and second radio transceiver in order to perform communication between the base station,
The communication control unit is configured to detect each of the wireless relay devices in a communicable state from each of the peripheral wireless relay devices by an IEEE 802.11 wireless LAN ad hoc mode;
A second means for detecting each of the wireless relay devices in a communicable state from each of the peripheral wireless relay devices by an IEEE802.11 wireless LAN infrastructure mode;
When the number of the wireless relay devices detected by the first means is larger than the number of the wireless relay devices detected by the second means, the wireless relay devices detected by the ad hoc mode are If one radio relay apparatus is selected and the number of radio relay apparatuses detected by the second means is greater than the number of radio relay apparatuses detected by the first means, the infrastructure mode A wireless relay device in a wireless communication system , comprising: a third means for selecting the one wireless relay device from each of the detected wireless relay devices. A wireless communication method for performing wireless communication between a plurality of communication terminals and a base station via a plurality of wireless relay devices,
In the wireless relay device in which communication with the base station is in a good state in each of the wireless relay devices, a first wireless transmission / reception unit responsible for communication with other wireless relay devices, and the communication terminal The communication terminal and the base station by the second and third wireless transmission / reception units of the second wireless transmission / reception unit and the third wireless transmission / reception unit responsible for communication with the base station Communication between
In the wireless relay device in which the communication with the base station is blocked in each of the wireless relay devices, one wireless relay device in each of the neighboring wireless relay devices by the first wireless transmission / reception unit In performing communication with the base station via the one wireless relay device by establishing communication with the base station,
Each of the wireless relay devices in a communicable state is detected from each of the peripheral wireless relay devices by an ad hoc mode of IEEE802.11 wireless LAN, and the peripheral of the peripheral device is detected by an infrastructure mode of IEEE802.11 wireless LAN. Detect each wireless relay device that is in a communicable state from within each wireless relay device ,
If the number of the wireless relay devices detected by the ad hoc mode is greater than the number of the wireless relay devices detected by the infrastructure mode, the wireless relay devices detected by the ad hoc mode are selected from the 1 If the number of the wireless relay devices detected by the infrastructure mode is larger than the number of the wireless relay devices detected by the ad hoc mode, the wireless relay device is detected by the infrastructure mode. A wireless communication method, wherein the one wireless relay device is selected from each of the wireless relay devices .

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