JP4818788B2 - Wireless device - Google Patents

Description

  The present invention relates to wireless technology, and more particularly to a wireless device that wirelessly relays a terminal device and a wired network.

  In recent years, a wireless LAN (Local Area Network) has attracted attention as a wireless communication system for realizing high-speed data communication. When a terminal device moves in a wireless LAN, a base station device that relays between the terminal device and the network needs to take measures against the influence of interference by other terminal devices as well as relay communication from both directions. Therefore, as one measure for reducing the influence of interference, for example, communication using weak radio waves is performed as compared with broadcasting. That is, by shortening the reach distance of the signal used for communication, it is possible to prevent interference from a terminal device located at a distance from the distance, and to reduce the amount of interference as a whole.

On the other hand, shortening the reach of the signal means that the range that can be directly communicated with the base station device is narrowed, and the importance of the relay device that relays communication with the terminal device located far from the base station device is important. The degree is getting higher and higher. Therefore, a single-hop relay system in which a terminal device communicates through only one relay device and a multi-hop relay system in which a terminal device communicates through a plurality of relay devices are desired. Conventionally, a multi-hop relay system that can be applied to a wireless LAN based on the IEEE 802.11 specification has been proposed. (For example, refer to Patent Document 1).
JP 2003-333053 A

  In general, in the multi-hop relay system, wireless communication between a terminal device and a network is wirelessly relayed by a base station device. However, due to instability of the wireless communication path, any path in the wireless relay may be disconnected, and communication may be interrupted in the terminal device.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a relay base station apparatus that can maintain a good wireless communication path for a terminal apparatus.

In order to solve the above-described problems, a wireless device according to an aspect of the present invention uses any one of a plurality of transmission rates via any one of at least one wireless communication path with a communication device to be communicated. a data communication unit for transmitting and receiving data packets Te, among the plurality of transmission rates, a hello packet following the transmission rate transmission rate used for the data packet is used in the data communication unit, at least one wireless communication path the hello packet for setting a hello packet communication unit for transmitting and receiving independently of the data packets, based on the hello packets sent and received in the hello packet communication unit, and the state of the wireless communication path a data packet is transmitted and received a state monitoring unit that monitors the state of another wireless communication path, data that are monitored by the state monitoring section If the packet is a state of the wireless communication path being sent and received has deteriorated, the another wireless communication path with a wireless communication path data packets are being transmitted or received, a path control section for switching a radio communication path a data packet is transmitted and received Is provided. When there is no other wireless communication path, the path control unit lowers the transmission rate used based on the data packet transmitted / received in the data communication unit .

  Here, the “communication device to be communicated” includes a terminal device, and also includes a base station device and a server. Further, the “wireless communication path” includes a propagation path between the wireless apparatus and the communication apparatus, and also includes a propagation path when relayed by a relay device arranged between the wireless apparatus and the communication apparatus. . The “transmission rate” includes a transmission amount per unit time. The transmission amount may be controlled by changing the multi-level number in the multi-level modulation scheme or the coding rate in the error correction coding scheme. The “control signal for setting a wireless communication path” includes broadcast information such as a hello packet, and also includes a reception response signal for a data packet. In addition, when the state of the wireless communication path has deteriorated, the communication device or relay device has failed, the reception quality has deteriorated, or the reception response signal such as an ACK signal has not been returned. Including.

  According to this aspect, when the state of the wireless communication path deteriorates, communication can be continued by switching to a wireless communication path different from the wireless communication path through which the data signal is transmitted and received.

“When there is no other wireless communication path” includes the case where the state of all the wireless communication paths is worse than a predetermined state. According to this aspect, when there is no other wireless communication path to be switched to, the communication rate can be easily continued in the wireless communication path in which communication is performed by reducing the transmission rate used in the data communication unit. .

  Another aspect of the present invention is a relay base station device that relays a radio signal between a terminal device and a backbone base station device wired to a network. The relay base station apparatus monitors the state of the wireless communication path with the backbone base station apparatus, thereby determining the effectiveness of the wireless communication path, and the monitoring determination section When it is determined that there is no valid wireless communication path, the terminal device already authenticated by the relay base station device is rejected while rejecting the signal requesting authentication from the terminal device. On the other hand, a control unit that transmits a signal indicating that communication with the relay base station device is not authenticated to the terminal device is provided.

  Here, “basic base station apparatus” and “relay base station apparatus” are names for convenience, and these base station apparatuses may have the same function or different functions. In addition, the “core base station apparatus” may be a base station apparatus that relays to another wireless communication path. In addition, the “effectiveness of the wireless communication path” includes not only an index indicating whether or not the wireless communication via the wireless communication path can be performed, but also the wireless communication via the wireless communication path as “ An indicator indicating whether or not to execute is included. In addition, the “wireless communication path between the backbone base station apparatus” includes a wireless communication path that exists between the backbone base station apparatus and the relay base station apparatus. For example, the backbone base station apparatus and the own relay base station apparatus Communication between the backbone base station device and the relay base station device and other relays in the communication between the backbone base station device and the relay base station device. In the case of going through the base station device, a wireless communication path between another relay base station device and the backbone base station device is also included. In addition, the “signal indicating that communication is not authenticated” includes a signal (DeAuthentication) indicating that authentication is not possible, as defined in IEEE 802.11. Further, “transmitting a signal not authenticating communication to the terminal device” includes a process of disconnecting communication with the terminal device.

  According to this aspect, when there is no valid wireless communication path, while rejecting the signal requesting authentication from the terminal device, the terminal device already authenticated by the relay base station device, By transmitting a signal indicating that communication with the relay base station device is not authenticated to the terminal device to the wireless communication unit, it is possible to supply the terminal device with a trigger for searching for another relay base station device. In addition, this enables the terminal device to execute communication with the relay base station device having an effective wireless communication path, so that a stable communication environment can be obtained. In addition, since communication is not performed with a relay base station apparatus having an invalid wireless communication path, it is possible to efficiently suppress the occurrence of useless communication.

  The control unit, when a valid wireless communication path with the backbone base station apparatus is confirmed by the monitoring determination unit, and when the signal requesting authentication from the terminal apparatus is received, the relay base station After the signal for authenticating the communication to the device is transmitted to the terminal device, and the signal for authenticating the communication to the relay base station device is transmitted to the terminal device, the monitoring and determining unit has one effective wireless communication path. If it is determined that it does not exist and if a signal requesting authentication from the terminal device is received, a signal requesting authentication from the terminal device is rejected while Communication may be disconnected.

  Here, the “signal for authenticating communication” includes a signal (Authentication) indicating authentication defined in IEEE 802.11. Further, “disconnecting communication with the terminal device” includes transmitting a signal indicating that the communication is not authenticated to the terminal device. In addition, “when the monitoring determination unit determines that no valid wireless communication path exists after transmitting a signal indicating authentication to the terminal device” includes the following three cases. (1) In the first case, notification from the base station apparatus constituting the relay path with the own relay base station apparatus or another relay base station apparatus existing between the base base station apparatus This is a case where information cannot be received for a certain period of time. (2) The second case is that the broadcast information transmitted from the basic base station apparatus or the basic base station apparatus held by the relay base station apparatus, the basic base station apparatus, or the basic base station This includes the case where the current broadcast information transmitted from the station device no longer matches. (3) Directly connecting between the relay base station device and another relay base station device when passing through another relay base station device in a wireless communication path between the relay base station device and the backbone base station device This includes a case where the state of the wireless communication path is valid and the state of the direct wireless communication path connecting another relay base station apparatus and the backbone base station apparatus becomes invalid.

  According to this aspect, when the wireless communication path to the backbone base station apparatus transitions from the valid state to the invalid state, the communication with the terminal apparatus is disconnected and the authentication request from the terminal apparatus is received. However, by rejecting it, a trigger for searching for another relay base station device can be supplied to the terminal device. In addition, this enables the terminal device to execute communication with the relay base station device having an effective wireless communication path, so that a stable communication environment can be obtained. In addition, since communication is not performed only with the relay base station apparatus having an invalid wireless communication path, it is possible to efficiently suppress the occurrence of useless communication.

  The monitoring determination unit detects a new wireless communication path with the backbone base station device, and the control unit has a wireless communication path newly detected by the monitoring determination unit that is better than the already detected wireless communication path. In the case of a wireless communication path, communication with the terminal device may be continued while switching to a good wireless communication path.

  Here, “when the newly detected wireless communication path is a better wireless communication path than the already detected wireless communication path” includes the following two cases. (1) The first is a case where the number of relays to the basic base station apparatus in the newly detected wireless communication path is smaller than the number of relays in the already detected wireless communication path. (2) Second, the number of relays to the basic base station apparatus in the newly detected wireless communication path is the same as the number of relays in the already detected wireless communication path, and the newly detected wireless The broadcast information from the relay base station device or the backbone base station device in the communication path is more than a certain level than the reception quality of the broadcast information from the relay base station device or the backbone base station device in the already detected wireless communication path It is a high case. According to this aspect, by switching to the newly detected wireless communication path, it is possible to continue communication with the terminal device without affecting the terminal device.

  The monitoring determination unit detects a new wireless communication path with the backbone base station device, and the control unit confirms the effective wireless communication path with the backbone base station device by the monitoring determination unit. Even when the state of the wireless communication path deteriorates, if the wireless communication path newly detected by the monitoring determination unit is valid, the communication with the terminal device is performed while switching to the good wireless communication path. You may continue.

  Here, “the case where the wireless communication path newly detected by the monitoring determination unit is valid even when the state of the wireless communication path deteriorates” includes the following two cases. (1) The first is a case where the number of relays to the basic base station apparatus in the newly detected wireless communication path is the same or one more than the number of relays in the already detected wireless communication path. . (2) Second, the reception quality of the broadcast information from the basic base station apparatus in the newly detected wireless communication path or another relay base station apparatus existing between the basic base station apparatus and a certain level or more This is the case. Even if the state of the wireless communication path deteriorates according to this aspect, if the newly detected wireless communication path is valid, the terminal device is not affected by switching to the wireless communication path. Communication with the terminal device can be continued.

  You may further provide the alerting | reporting part which alert | reports the alerting | reporting information containing the information regarding a wireless communication path | route with a predetermined period. When the signal strength acquired based on the notification information from other relay base station devices in the wireless communication path is smaller than a predetermined threshold, the monitoring determination unit and other relay base station devices and the relay base It may be determined that the wireless communication path between the station devices is not valid.

  According to this aspect, when the signal strength acquired based on the broadcast information from the other relay base station device in the wireless communication path is smaller than the predetermined threshold, the other relay base station device and the relay base By determining that the wireless communication path between the station apparatuses is not effective, it is possible to efficiently suppress the occurrence of useless communication in the terminal apparatus.

  You may further provide the alerting | reporting part which alert | reports the alerting | reporting information containing the information regarding a wireless communication path | route with a predetermined period. The monitoring determination unit determines the validity of the wireless communication path between the other relay base station apparatus and the backbone base station apparatus in the wireless communication path based on the notification information from the other relay base station apparatus in the wireless communication path. And the validity of the wireless communication path to the basic base station apparatus via another base station apparatus may be determined based on the validity.

  According to this aspect, the effectiveness of the wireless communication path between the other relay base station apparatus and the backbone base station apparatus in the wireless communication path is determined based on the notification information from the other relay base station apparatus in the wireless communication path. By acquiring the validity and determining the validity of the wireless communication path to the basic base station apparatus via another base station apparatus based on the validity, occurrence of useless communication in the terminal apparatus can be efficiently suppressed. .

  You may further provide the alerting | reporting part which alert | reports the alerting | reporting information containing the information regarding a wireless communication path | route with a predetermined period. When the monitoring determination unit cannot continuously receive broadcast information from other relay base station devices in the wireless communication path, the wireless communication path between the other relay base station device and the relay base station device is valid. It may be determined that it is not.

  Here, the “information about the wireless communication path” includes information about the wireless communication path between the backbone base station apparatus and the terminal apparatus via the relay base station apparatus, and identification information for identifying the relay base station apparatus And the amount of communication, communication quality, and other control information in the wireless communication path.

  According to this aspect, even when information about a wireless communication path from another relay base station apparatus can be received, broadcast information from other relay base station apparatuses in the wireless communication path cannot be received continuously. In this case, it is possible to maintain a good communication environment for the terminal device by determining that the wireless communication path between the other relay base station device and the relay base station device is not effective, and waste in the terminal device. Generation of unnecessary communication can be efficiently suppressed.

  The monitoring determination unit is broadcast information from other relay base station devices in the wireless communication path, and includes information related to the effectiveness of the wireless communication path between the backbone base station device and the other relay base station device. If the broadcast information being monitored cannot be continuously monitored, it may be determined that the wireless communication path to the basic base station device via another base station device is not valid.

  According to this aspect, when the broadcast information including information on the effectiveness of the wireless communication path between the backbone base station apparatus and another relay base station apparatus cannot be continuously monitored, the other base station apparatus is By determining that the wireless communication path to the basic base station device is not effective, it is possible to efficiently suppress the occurrence of useless communication in the terminal device.

  You may further provide the alerting | reporting part which alert | reports the alerting | reporting information containing the information regarding a wireless communication path | route with a predetermined period. Based on the broadcast information acquired via the wireless communication unit, the monitoring determination unit is another relay base station device with a smaller number of relays, or another relay base station that broadcasts information with higher received electric field strength. The device or another relay base station device that is not the target of detection of transmission failure is detected, and the control unit is effective between the backbone base station device and the relay base station device in the monitoring determination unit. Even when it is determined that there is no wireless communication path, if another relay base station device that can be relayed to the basic base station device is detected by the monitoring determination unit, the relay base station Communication with the station device may be continued.

  According to this aspect, even when it is determined that there is no effective wireless communication path, the monitoring determination unit detects the basic base station device or another relay base station device that can relay to the basic base station device. In this case, a stable communication environment can be realized by continuing communication with the relay base station device with respect to the terminal device.

  Another aspect of the present invention is a base station apparatus. The base station device performs wireless communication with a terminal device through a wireless line and relays a wireless signal from another base station device, and another base station through the wireless communication unit. From the other base station apparatus in the receiving part which receives the alerting | reporting information alert | reported from the other base station apparatus via the alerting | reporting part which alert | reports alerting information with a predetermined period with respect to an apparatus, and a radio | wireless communication part When the broadcast information is received at a predetermined cycle, the number of receptions for other base station devices is increased, and when the reception information is not received at the reception unit at a predetermined cycle, the number of receptions. Counter unit for measuring the number of receptions of control signals from other base station devices, and when the number of receptions measured in the counter unit is larger than a threshold value, base And a relay permission part for permitting the relay between the devices. When the measured number of receptions matches the threshold value, the counter unit adds a predetermined value to the number of receptions.

  Here, “broadcast information” includes information for establishing or maintaining a communication line, and includes, for example, a hello packet having a parameter such as the number of relays. In addition, “when notification information is received” includes that the notification information has been successfully demodulated at a desired timing. In addition, the “number of receptions” includes a value indicating the stability of the communication line with other base station devices, for example, the total number of normal receptions from the first reception to the most recent reception. In addition, the number of times of normal reception being subtracted from the total number of normal receptions at the desired timing is included. According to this aspect, a stable communication line can be constructed by executing relay control according to the number of times of reception of broadcast information broadcast from other base station devices. In addition, because communication with the base station device that built the communication line is stable, a predetermined value is added to the number of receptions of the base station device, and backward protection is used to prevent unintentional disconnection of the communication line. it can.

  When the reception unit receives a control signal from another base station device again when the number of receptions from the other base station device is larger than the threshold value, the counter unit sets a predetermined value to the threshold value. The added value may be set as the number of receptions. According to this aspect, when the control signal is accepted again while the number of receptions from other base station devices is larger than the threshold value, by adding a predetermined value to the threshold value, By increasing the number of receptions indicating stability, the communication line can be protected backward. That is, unintentional disconnection of the communication line can be prevented, and the communication line network can be stabilized.

  The relay permitting unit is a base station device with a smaller number of relays, or another base station device that has broadcasted broadcast information with a higher received electric field strength, or is not subject to detection of transmission failure. This base station device may be permitted to relay with priority over another base station device other than other base station devices. Here, “another base station device that has not been a target of detection of transmission failure” refers to a case where an ACK (Acknowledge) signal or a NACK (Non-Acknowledge) signal is received from the base station device, or the base station This includes the case where an ACK signal is received from the device. In other words, another base station apparatus that is the target of detection of transmission failure cannot receive an ACK signal or a NACK signal transmitted from the base station apparatus or transmitted from the base station apparatus. This is a source base station apparatus when the received NACK signal is received by the base station apparatus. The ACK signal / NACK signal is a signal indicating a confirmation notification. The ACK signal is transmitted to the base station device when the signal transmitted by the base station device is correctly received by the desired base station device, and the NACK signal is transmitted to the desired base station. Sent when the device fails to receive correctly. According to this aspect, a stable communication path can be established by preferentially adding a base station apparatus that has broadcast information with a small number of relays or a higher received electric field strength to the communication path. In addition to preventing disconnection of a communication path with a highly stable base station apparatus, establishing a more stable communication path by establishing a communication path with a base station apparatus having a small number of relays, etc. it can. In addition, the communication path of the entire system can be optimized.

  When the number of receptions is greater than the threshold, the counter unit has received the broadcast information from the other base station apparatus by receiving the data signal from the other base station apparatus related to the broadcast information instead of the broadcast information. You may judge things. According to this aspect, even when the broadcast information is not normally received from a highly stable base station apparatus that has already established a communication line, if the data signal is received, the data signal By determining that the broadcast information has been received upon reception, unintentional disconnection of the communication line can be prevented, and the communication line network can be stabilized.

  Another aspect of the present invention is an authentication method. This method includes a step of notifying other base station devices of its own notification information at a predetermined period, a step of receiving notification information notified from other base station devices, and a notification from other base station devices. If the information is accepted, increase the number of receptions for other base station devices, and if the broadcast information from other base station devices is not accepted, measuring the number of receptions by decreasing the number of receptions, Permitting relay of wireless communication with another base station apparatus when the number of receptions is greater than the threshold. In the step of measuring, when the measured number of receptions matches the threshold value, a predetermined value is added to the number of receptions. According to this aspect, a stable communication line can be constructed by executing relay control according to the number of times of reception of broadcast information broadcast from other base station devices. In addition, because communication with the base station device that built the communication line is stable, a predetermined value is added to the number of receptions of the base station device, and backward protection is used to prevent unintentional disconnection of the communication line. And the communication network can be stabilized.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, a stable communication environment can be maintained in a multi-hop relay system.

  Before the embodiments of the present invention are specifically described, an outline is first described. Embodiments described herein relate generally to a communication system using a multi-hop relay scheme. The communication system according to the present embodiment includes a base station device (hereinafter referred to as “core base station device”) wired to a network, and a base station device (hereinafter referred to as “base station device”) that relays wireless communication from the core base station device. And a terminal device that performs wireless communication with the backbone base station device via the relay base station device or directly performs wireless communication with the backbone base station device. including. The relay base station apparatus determines the path of the wireless communication path between the terminal apparatus and the backbone base station apparatus according to the reception status of the broadcast information broadcast from the backbone base station apparatus or another relay base station apparatus. Control establishment and maintenance.

  Generally, since a wireless communication line is unstable, it is difficult to realize a stable communication environment. For example, when the terminal device and the backbone base station device are performing communication via the relay base station device, the wireless communication path between the backbone base station device and the relay base station device is disconnected during the communication. Sometimes. In such a case, the terminal device cannot continue communication with the backbone base station device. Also, when there is no effective wireless communication path between the backbone base station device and the relay base station device at the start of communication, the terminal device connected to the relay base station device cannot execute communication. It becomes. In such a case, the terminal device not only performs useless communication with the relay base station device, but also interrupts communication with the backbone base station device, which is inconvenient for the user who uses the terminal device.

  Therefore, in the embodiment of the present invention, the relay base station device determines the validity of the wireless communication line with the backbone base station device, and selects a better wireless communication line, whereby the backbone base station device To stabilize the communication environment between the terminal device and the terminal device. Details will be described later.

  FIG. 1 shows a configuration example of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a wired network 200, a first server 10, a second server 20, a backbone base station device 32 represented by a base station device 30, a first relay base station device 34, and a second relay base station device. 36 and a terminal device 40. The wired network 200 is a wired communication network such as the Internet. The first server 10 and the second server 20 are connected to the wired network 200 and control the base station device 30. The first server 10 is connected to the basic base station apparatus 32 via a wired line. The backbone base station device 32, the first relay base station device 34, or the second relay base station device 36 communicates with the terminal device 40 via each of the fourth wireless communication path 640 to the sixth wireless communication path 660. Execute. In addition, the backbone base station device 32, the first relay base station device 34, and the second relay base station device 36 communicate with each other via each of the first wireless communication path 610 to the third wireless communication path 630. Execute. In other words, the core base station device 32, the first relay base station device 34, or the second relay base station device 36 relays communication with the terminal device 40 to each other.

  In FIG. 1, only the first server 10 and the second server 20 are illustrated as servers for the sake of simplicity, but other servers may exist. Moreover, although only the base station device 30 connected to the first server 10 is illustrated, the second server 20 may be connected to another base station device through a wired line as well. Further, although the basic base station device 32 is illustrated as the base station device 30 that is connected to the first server 10 by wire, other basic base station devices may be connected. Moreover, although only one terminal device 40 is illustrated, there may be other terminal devices that perform communication with a predetermined base station device 30. The wireless multi-hop network described in the present embodiment may be realized by a known method, for example, “T. Clause, one other person,“ Optimized Link State Routing Protocol (OLSR protocol) ”, IETF RFC3626, The OLSR protocol described in “October 2003” may be applied.

  The terminal device 40 may be directly connected to the basic base station device 32. Further, the terminal device 40 may be connected to the first server 10 via the first relay base station device 34 or the second relay base station device 36. Further, the terminal device 40 may be connected to the first server 10 by being relayed to the backbone base station device 32 via the first relay base station device 34 and the second relay base station device 36. Thus, the system flexibility is improved by establishing a plurality of wireless communication paths. For example, there is a shield between the terminal device 40 and the backbone base station device 32 and between the second relay base station device 36, and further, the backbone base station device 32 and the first relay base station When the amount of communication between the devices 34 is large, there is a case where the throughput decreases in communication with the first server 10 via the first relay base station device 34. In such a case, the terminal device 40 first performs communication with the first relay base station device 34, and the first relay base station device 34 relays communication with the terminal device 40 to the second relay base station device 36. Then, the second relay base station device 36 relays to the first server 10. By taking such an aspect, the terminal device 40 can realize a comfortable communication environment with the basic base station device 32.

  Hereinafter, a case where the first relay base station device 34 relays communication between the terminal device 40 and the backbone base station device 32 will be described. The first relay base station device 34 executes the following processing for (1) establishment, (2) maintenance, and (3) switching / disconnection of the wireless communication path toward the backbone base station device 32.

  (1) In the initial state where the wireless communication path is not established, when there is an authentication request from the terminal device 40, the first relay base station device 34 rejects the request. When establishing a wireless communication path, the first relay base station device 34 first broadcasts a hello packet. In addition, a hello packet broadcast from another base station device 30 is received. When this reception is normally executed, the first relay base station device 34 recognizes the other base station device 30 and determines that the wireless communication path to the base station device 30 is valid. When there are a plurality of base station apparatuses 30 that have successfully received the hello packet, it is determined that the wireless communication paths of the plurality of base station apparatuses 30 are valid. In this case, any one wireless communication path is selected.

  When the terminal device 40 requests authentication of communication after establishing the wireless communication path, the first relay base station device 34 determines whether or not it can relay to the backbone base station device 32. Specifically, the effectiveness of the first wireless communication path 610 between the first relay base station device 34 and the backbone base station device 32 is determined. For example, the determination may be made according to the reception intensity obtained based on the notification information notified from the basic base station apparatus 32. Further, the determination target may be not only the first wireless communication path 610 but also the second wireless communication path 620 and the third wireless communication path 630. In this case, although the number of relays to the backbone base station apparatus 32 is larger than that of the first wireless communication path 610, the terminal apparatus 40 is connected to the second wireless communication path 610 even if the first wireless communication path 610 is invalid. Communication can be executed via the communication path 620 and the third wireless communication path 630.

  If there is an effective wireless communication path based on the above determination, the first relay base station apparatus 34 establishes the wireless communication path. In addition, the first relay base station device 34 notifies the terminal device 40 that communication authentication is permitted. When it is determined that there are a plurality of valid wireless communication paths, the first relay base station device 34 may establish a wireless communication path for a path with a small number of relays. Further, even if a route has a larger number of relays by a predetermined value than a route having the smallest number of relays, if the reception strength is good, a wireless communication route may be established for that route. In addition, when a wireless communication path is established, contents regarding path information included in a hello packet to be notified later may be updated.

  (2) After starting communication with the terminal device 40, the first relay base station device 34 performs adaptive modulation control, and sets an optimal transmission rate according to the environment of the wireless communication path. In adaptive modulation control, the signal strength of the received data packet is measured, and the transmission rate may be changed according to the signal strength. For example, when the signal strength of a data packet is good, the transmission rate of the data packet is increased, and when the signal strength of the data packet is bad, the transmission rate may be lowered. Note that adaptive modulation control may be realized by other known techniques.

  Further, the first relay base station device 34 periodically searches for another wireless communication path as a switching destination candidate when the state of the wireless communication path in communication deteriorates. This search may be executed based on the hello packet described in (1). The state of the wireless communication path determined to be valid is periodically monitored. The state of the wireless communication path is determined according to the received signal strength of the hello packet and the frequency of normal reception of the hello packet. When the received signal strength falls below a predetermined threshold value, or when hello packets cannot be received continuously for a predetermined number of times, the wireless communication path is determined to be invalid. When the wireless communication path determined to be invalid is a wireless communication path that is currently communicating, the first relay base station device 34 switches the path to an effective wireless communication path.

  (3) Even if the wireless communication path that is currently being communicated becomes invalid, if any one of the wireless communication paths is valid, the first relay base station apparatus 34 sets the effective wireless communication path to By switching, the relay between the terminal device 40 and the backbone base station device 32 can be continued. For example, even if the communication path of the first radio communication path 610 is invalid, if the second radio communication path 620 and the third radio communication path 630 are valid, the first relay base station apparatus 34 2 Relaying to the basic base station apparatus 32 via the relay base station apparatus 36 is possible. Note that the wireless communication path switching process is performed after disconnecting a wireless communication path that has already been performing communication and then switching to a new wireless communication path, but with communication authentication for the terminal device permitted. May be.

  Further, even a base station apparatus that has already performed relay processing may subsequently shift to a state unfavorable for relaying due to deterioration of propagation quality or the like. In such a case, the relay process is disconnected. However, as an instantaneous phenomenon, when a hello packet is not received accidentally, it is determined that the wireless communication path is invalid in such a situation, and the relay processing with the base station apparatus in a stable state is disconnected. That is not preferred. Therefore, in the embodiment of the present invention, after shifting to the stable state, priority is given to continuing the stable state, preventing frequent transition to the unstable state, improving the stability of the system, Therefore, the problem caused by the hello packet non-delivery state by the hidden terminal is solved.

  In addition, the first relay base station device 34 determines the wireless communication path by the following procedure when the reception of the hello packet fails or the transmission of the data packet fails in the currently communicating wireless communication path. Judge whether to switch. Here, the case where the reception of the hello packet has failed means that the hello packet to be transmitted from the base station apparatus on the currently communicating wireless communication path is not transmitted, or the first relay base station apparatus 34 receives the hello packet. This includes a case where the signal strength of the hello packet is lower than a predetermined threshold. The case where the transmission of the data packet has failed means that the first relay base station apparatus 34 has not received a reception response signal for the data packet after the first relay base station apparatus 34 has transmitted the data packet. Including.

  When the reception of the hello packet fails or when the transmission of the data packet fails, first, the first relay base station device 34 checks whether there is another effective wireless communication path. If another valid wireless communication path exists, the first relay base station device 34 switches to that path. If there is no other valid wireless communication path, communication on the current wireless communication path is continued by lowering the data packet transmission rate. By reducing the transmission rate of the data packet, the throughput can be reduced, but the reception performance can be improved.

  As described above, the wireless communication path is selected by the hello packet. On the other hand, the transmission rate of the data packet is selected according to the signal strength of the data packet. Here, a transmission rate equal to or lower than the transmission rate used for the data packet is used as the transmission rate of the hello packet. Then, since the wireless communication path is selected by the hello packet, the wireless communication path may be an unsuitable path depending on the transmission rate of the data packet.

  In the present embodiment, the wireless communication path is switched to another effective wireless communication path when the reception of the hello packet fails or the transmission of the data packet fails. Here, when there is no other effective wireless communication path, the transmission rate of the data packet is lowered regardless of the state of adaptive modulation processing for the data packet. By reducing the data packet transmission rate, the data packet transmission rate approaches the hello packet transmission rate. If it does so, as long as communication is performed by the radio | wireless communication path selected by the hello packet, communication will be stabilized. If the transmission rate is already set to the lowest rate, the communication may be disconnected.

Here, in the case of “switching to an effective wireless communication path”, a wireless communication path that satisfies any of the following conditions may be selected as the wireless communication path to be switched to.
(3-1) The first case is when the number of relays to the basic base station apparatus 32 in the newly detected wireless communication path is smaller than the number of relays in the already detected wireless communication path.

  (3-2) Secondly, the number of relays to the basic base station apparatus 32 in the newly detected wireless communication path is the same as the number of relays in the already detected wireless communication path, and the newly detected The broadcast information received from the relay base station apparatus or backbone base station apparatus 32 in the received wireless communication path is better than the reception quality of the broadcast information from the relay base station apparatus or backbone base station apparatus 32 already detected in the wireless communication path. This is the case when it is higher than a certain level. According to this aspect, the communication with the terminal device 40 can be continued without affecting the terminal device 40 by switching to the newly detected wireless communication path.

  (3-3) The third case is when the number of relays to the basic base station apparatus in the newly detected wireless communication path is the same or one more than the number of relays in the already detected wireless communication path It is. For example, as an effective wireless communication path between the backbone base station apparatus 32 and the first relay base station apparatus 34, there are two wireless communication paths: a first wireless communication path 610 and a second wireless communication path 620 → a third wireless communication path 630. When there is a route, in principle, the route of the first wireless communication route 610 having a smaller number of relays is selected.

  However, when the communication state of the first wireless communication path 610 becomes invalid due to deterioration or the like, the first relay base station apparatus 34 changes the path from the first wireless communication path 610 to the basic base station apparatus 32. By switching from the second wireless communication path 620 to the third wireless communication path 630, communication with the backbone base station apparatus 32 can be continued, and thus communication of the terminal apparatus 40 can be maintained. In this case, the number of relays increases from “1” to “2”. However, an increase of about “1” has little effect on the terminal device 40, and therefore, the communication is performed by switching the route rather than disconnecting the communication. It is preferable to maintain. The number that can be increased is not limited to “1” described above, but may be a value greater than or equal to “2”.

  (3-4) Fourth, the reception quality of broadcast information from the basic base station apparatus or another relay base station apparatus existing between the basic base station apparatus and the basic base station apparatus in the newly detected wireless communication path is constant. This is the case when the level is over. Even if the state of the wireless communication path deteriorates according to this aspect, if the newly detected wireless communication path is valid, the terminal device is not affected by switching to the wireless communication path. Communication with the terminal device can be continued. In the above case, it is not determined that no effective wireless communication path exists, and communication with the terminal device is continued.

  On the other hand, when it is determined that there is no valid wireless communication path, the first relay base station device 34 notifies the terminal device 40 that communication is not authenticated. In response to the notification, the terminal device 40 searches for another relay base station device and tries a process for continuing communication. Note that “when it is determined that there is no valid wireless communication path” includes the following three cases.

(3-5) In the first case, the state in which the broadcast information cannot be received from the basic base station apparatus 32 or the second relay base station apparatus 36 existing between the basic base station apparatus 32 for a certain period of time It is a case to continue.
(3-6) In the second case, the basic base station device 32 held by the first relay base station device 34 or past broadcast information transmitted from the basic base station device 32 and the basic base This is a case in which the current broadcast information transmitted from the station device 32 or the basic base station device 32 no longer matches.
(3-7) The third case is a case where the state of the direct wireless communication path from the first relay base station device 34 to the backbone base station device 32 becomes invalid. This state may be recognized from broadcast information transmitted from the basic base station device 32.

  FIG. 2 shows a configuration example of the first relay base station apparatus 34 or the second relay base station apparatus 36 of FIG. Hereinafter, for convenience of explanation, the configuration of the first relay base station apparatus 34 will be described. The second relay base station device 36 has the same configuration as that of the first relay base station device 34. The first relay base station device 34 includes a radio communication unit 50, a generation unit 52, a control unit 60, and a monitoring determination unit 62. In addition, the wireless communication unit 50 includes a reception unit 54 and a transmission unit 56.

  The wireless communication unit 50 communicates with a terminal device 40 (not shown) using any one of a plurality of frequency bands, and executes a relay process between the backbone base station device 32 or the second relay base station device 36. To do. The relay processing includes reception of a signal transmitted from the terminal device 40 by the reception unit 54 and transmission of the signal to the backbone base station device 32 or the second relay base station device 36 by the transmission unit 56. The reception unit 54 receives the signal transmitted from the device 32 and transmits the signal to the terminal device 40 by the transmission unit 56.

  The receiving unit 54 receives a signal such as a data packet or a notification signal such as a hello packet transmitted from another base station device 30 or the terminal device 40. At that time, the received notification signal is notified to the monitoring determination unit 62. The monitoring determination unit 62 monitors the wireless communication path based on the notified notification signal, and executes path establishment, maintenance, switching, or disconnection processing. In addition, the reception unit 54 receives a reception response signal for the data packet from another base station device 30 and notifies the control unit 60 of the reception response signal. The reception response signal may include an ACK signal indicating successful reception, an identification number indicating the transmission source base station device 30, and the like.

  The generation unit 52 generates notification information to be notified to the base station device 30. The broadcast information includes information related to the wireless communication path. For example, the terminal device 40 and the relay destination trunk base station device 32 or the second relay base station device 36 that are communication targets in the wireless communication unit 50 It includes group identification information (hereinafter referred to as “ESS-ID”) indicating a group to be included, the number of relays to the basic base station apparatus 32, and the like. Further, the broadcast information may include not only ESS-ID but also information indicating the length of ESS-ID. Further, the generation unit 52 generates authentication information to be transmitted to the terminal device 40. The authentication information includes information indicating that communication with the first relay base station device 34 is permitted or communication with the first relay base station device 34 is not permitted. Here, the transmission unit 56 notifies a notification signal such as a hello packet generated by the generation unit 52 at a predetermined period.

  Here, the format of the notification information generated by the generation unit 52 will be described. FIG. 3 shows a configuration example of notification information notified by the wireless communication unit 50 of FIG. The hello packet 300 that is broadcast information includes a first header 310, a packet type 320, a second header 330, and a control message 340. The first header 310 includes information indicating the transmission source, the address of the access point of the transmission source, and information indicating that it is multicast, and defines the higher level protocol (IP (Internet Protocol) / ARP (Address). (Resolution Protocol) / VLAN (Virtual Local Area Network)). By making this a unique value, even if a wireless device that does not use this embodiment receives a hello packet, interference with other communications can be avoided. The packet type 320 includes information indicating an ether type defined by IEEE, and includes information fixed for each business operator and application. The second header 330 includes a type number for identifying information included in a control message 340 described later. The type number is composed of at least three, and indicates any one of own station information, information on the path configuration, and information for recognizing the other station. The control message 340 includes different contents depending on the type number indicated by the second header 330.

  For example, when the type number included in the second header 330 is a number indicating the local station information, the control message 340 includes channel information used by the base station device 30 and ESS-ID. In addition, when the type number included in the second header 330 is a number indicating information related to the path configuration, the control message 340 includes the base station device 30 that transmitted the hello packet 300 and the relayed base station device 30. The number is included. The “number of relayed base station devices 30” is also called the hop count. When the type number included in the second header 330 is information for recognizing the counterpart station state, the control message 340 includes the base station device 30 that has notified the reception confirmation notification and the hello packet 300, and the hello packet 300. Information indicating the stability of communication with the received base station apparatus 30 is included. The control message 340 in this case also includes information indicating the base station device 30 that should receive the hello packet 300.

  Returning to FIG. The monitoring determination unit 62 determines the validity of the wireless communication path by monitoring the state of the wireless communication path with the backbone base station device 32. When it is determined and reported that a valid wireless communication path exists by the monitoring determination unit 62, the control unit 60 updates the table indicating the validity. In addition, the control unit 60 establishes a wireless communication line and causes the terminal device 40 to transmit a notification to the effect of authenticating communication to the wireless communication unit 50. Here, when there is no effective wireless communication path in the wireless communication path reaching the basic base station device 32 in the table reported and updated by the monitoring determination unit 62, the control unit 60 determines that the terminal device 40 In response, the wireless communication unit 50 is caused to transmit a signal indicating that communication with the first relay base station device 34 is not authenticated.

  Specifically, when the monitoring determination unit 62 of the first relay base station device 34 cannot continuously receive the notification information from the backbone base station device 32 in the wireless communication path, the first wireless communication path 610 Determine that it is not valid. In addition, the monitoring determination unit 62 determines that the second wireless communication path 620 is valid when the signal strength acquired based on the notification information from the basic base station apparatus 32 in the wireless communication path is smaller than a predetermined threshold value. It may be determined that it is not. Similarly, the monitoring determination unit 62 determines the effectiveness of the second wireless communication path 620 with the second relay base station device 36 as well. Here, “validity” may include not only “valid” and “invalid” but also a state indicating an intermediate state thereof.

  Here, the monitoring determination unit 62 of the first relay base station device 34 cannot directly determine the effectiveness of the third wireless communication path 630. Therefore, the monitoring determination unit 62 acquires the validity of the third wireless communication path 630 based on the notification information from the second relay base station device 36, and based on the validity, Effectiveness may be determined. Specifically, the monitoring determination unit 62 can continuously monitor the notification information from the second relay base station device 36 and including information related to the effectiveness of the third wireless communication path 630. If not, it may be determined that the wireless communication path to the backbone base station device 32 via the second relay base station device 36 is not valid. Here, when one of the second wireless communication path 620 and the third wireless communication path 630 is invalid, the wireless communication path reaches the backbone base station apparatus 32 via the second relay base station apparatus 36. Is determined to be invalid.

  In the above description, when the control unit 60 confirms that no effective wireless communication path exists with the basic base station device 32 by referring to the table indicating the validity, the terminal device 40 In contrast, it has been described that a signal indicating that communication with the first relay base station apparatus 34 is not authenticated is transmitted. However, the control unit 60 may cause the monitoring determination unit 62 to execute the following processing prior to this transmission. The monitoring determination unit 62 may detect another relay base station device having a smaller number of relays as a relay destination base station device based on the broadcast information acquired from the other base station device 30. Further, another relay base station apparatus that has reported information with higher received electric field strength may be detected as a base station apparatus. Alternatively, another relay base station apparatus that has not been a target of detection of transmission failure is detected as a base station apparatus. Here, when another relay base station device that can be relayed to the backbone base station device 32 is detected by the monitoring determination unit 62, the control unit 60 determines that there is no effective wireless communication path in the monitoring determination unit 62. Even if it has been determined, the terminal device 40 is allowed to continue communication with the first relay base station device 34.

  The control unit 60 instructs the monitoring determination unit 62 to confirm the validity of the wireless communication path reaching the basic base station device 32 when the communication start request from the terminal device 40 is received. The monitoring determination unit 62 determines, for each base station device 30, the validity of the wireless communication path that reaches the base station device 30 based on the notification information notified by the other base station device 30. The effectiveness determined by the monitoring determination unit 62 is reported to the control unit 60 and managed as a table indicating the effectiveness by the control unit 60. Specifically, another relay base station device with a smaller number of relays is detected as a relay destination base station device. Further, another relay base station apparatus that has reported information with higher received electric field strength may be detected as a base station apparatus. Alternatively, another relay base station apparatus that has not been a target of detection of transmission failure is detected as a base station apparatus.

  Further, the control unit 60 measures the signal strength of the data signal notified by the receiving unit 54, and controls the transmission rate of the data signal according to the measured signal strength. Specifically, the transmission rate is controlled according to a table in which the ratio between the measured signal strength and the predetermined signal strength is associated with the transmission rate of the data signal. FIG. 4 is a diagram showing an example of a transmission rate control table 400 in the control unit 60 of FIG. As shown in the figure, the control table 400 includes a signal strength column 410 and a transmission rate column 420, and the transmission rate to be set is defined according to the ratio of the respective signal strengths. The signal strength may be an RSSI (Received Signal Strength Indicator) or an S (Signal) / N (Noise) ratio.

  When the state of the wireless communication path monitored by the monitoring determination unit 62 deteriorates, the control unit 60 performs wireless communication in which the data signal is transmitted / received through a wireless communication path different from the wireless communication path through which the data signal is transmitted / received. Switch the route. “Deterioration” means, for example, when the detected current signal strength is lower than the past signal strength, or when the reception response signal notified by the receiving unit 54 is not accepted, that is, a transmission failure is detected. Including the case. In such a case, the control unit 60 refers to a table indicating validity and confirms whether there is another valid wireless communication path. As a result of the confirmation, if another valid wireless communication path exists, the control unit 60 switches the current wireless communication path to another valid wireless communication path. By switching, data signal communication can be continued stably.

  On the other hand, when there is no other effective wireless communication path, the data signal transmission rate is lowered stepwise. The stepwise reduction includes, for example, when the transmission rate of the data signal is “48 Mbps” in the transmission rate column 420 of the control table 400 illustrated in FIG. 4, it is set to “36 Mbps” below that column. . By lowering the transmission rate in stages, it is possible to stabilize the communication state while suppressing an extreme decrease in throughput. Note that the control table 400 illustrated in FIG. 4 is an example, and the transmission rate may be controlled using another table in which the signal strength and the transmission rate are associated with each other.

  FIG. 5 shows a configuration example of the monitoring determination unit 62 of FIG. The monitoring determination unit 62 includes a reception unit 70, a counter unit 72, and a route determination unit 74. Here, the monitoring determination unit 62 determines the validity of the wireless communication path for each base station device 30 that can be a counterpart by monitoring the received notification information, and determines the communication path via the wireless communication path. Determine whether to establish, maintain, switch or disconnect. Note that the base station device 30 to be monitored in the monitoring determination unit 62 is identified by information for identifying the base station device 30 included in the broadcast information.

  The accepting unit 70 accepts notification information notified from another base station device via the wireless communication unit 50. This acceptance process is executed at a predetermined cycle for each base station device 30 related to the broadcast information. When the reception unit 70 receives notification information from another base station device 30 at a desired timing corresponding to a predetermined cycle, the counter unit 72 increases the number of receptions related to the base station device 30. On the other hand, if the reception unit 70 does not receive broadcast information from another base station device at a desired timing, the number of receptions is decreased. Here, the number of receptions indicates the stability of the communication line between the base station apparatus related to the broadcast information and the base station apparatus.

  Here, when the number of times of reception, which is the stability, matches the threshold value, it can be determined that the base station device 30 that has notified the broadcast information related to the number of times of reception has shifted to a stable state. A predetermined value is added to the number of times. By adding a predetermined value, the stability of the base station device 30 is trusted and stable even when the broadcast information broadcast from the base station device 30 is not normally received thereafter. Do not shift from a state to an unstable state. In other words, if an unstable condition occurs between the base station apparatus 30 and the high-stability base station apparatus 30 and the broadcast information is not received about once or twice, the suspicion of the stability is the stability of the communication path. It is not preferable from the viewpoint of maintaining the property. Therefore, it was decided to avoid disconnection of the communication path by adding a predetermined value.

  Similarly, the counter unit 72, when the reception information from the other base station device 30 is received again by the receiving unit 70 when the number of receptions from the other base station device 30 is larger than the threshold, A value obtained by adding a predetermined value to the threshold is set as the number of receptions. In other words, in the stable state, when the notification information is normally received, the stability is maximized by relaxing the stability continuity condition, and the condition for shifting to instability is tightened. Further, when the number of receptions is larger than the threshold value, the counter unit 72 receives the data signal from the other base station apparatus related to the broadcast information instead of the broadcast information, and notifies the broadcast information from the other base station apparatus. May be determined. This is because even in such a case, it is considered that the communication path with the base station apparatus is stable.

  The signal strength acquisition unit 76 acquires the signal strength for the route with the notified base station device 30 based on the notified signal via the receiving unit 70. The signal strength may be acquired by measuring the signal strength of the notified signal, or may be acquired from information on the signal strength included in the notified signal. The signal strength may be a received electric field strength of a signal, or may be a signal-to-noise ratio or a signal-to-interference signal ratio.

  The route determination unit 74 first determines whether or not relaying to the monitored base station device 30 is possible. When the number of receptions measured by the counter unit 72 is larger than the threshold value, it is determined that the wireless communication unit 50 can relay to another base station device 30 related to the number of receptions. The route determination unit 74 may determine that relaying to another base station apparatus having a smaller number of relays is possible based on the relay number information included in the broadcast information. In addition, the route determination unit 74 has priority over other base station devices other than the other base station devices over other base station devices that have notified the broadcast information with higher signal strength acquired by the signal strength acquisition unit 76. Therefore, it may be determined that relaying is possible. Further, regarding the broadcast information transmitted to the other station, if it is not detected that any transmission confirmation response of the ACK signal or the NACK signal has not been received, it may be determined that relaying is possible. In addition, these processes may be implement | achieved by determining using a data signal or the frequency | count of relay, reception quality, etc. which were contained in alerting | reporting information.

  Next, when it is determined that relaying is possible, the route determination unit 74 selects any one of the base station devices 30, validates the wireless communication route that reaches the base station device 30, and sends it to the control unit 60. Report. Further, the route determination unit 74 determines that a wireless communication route other than the wireless communication route determined to be valid is invalid, and similarly reports to the control unit 60. When determining the second relay base station device 36, the effectiveness of the third wireless communication path 630 reaching the backbone base station device 32 is determined based on the notification information from the second relay base station device 36. . In this case, only when the relay to the second relay base station apparatus 36 is possible and the third wireless communication path 630 is valid, the path determination unit 74 performs the backbone via the second relay base station apparatus 36. It is determined that the wireless communication path to the base station apparatus 32 is valid.

  By taking the above-described mode, it is possible to maintain a stable state even in a state where it is difficult to receive notification information at high loads. Further, the path determination unit 74 is a more preferable base station apparatus regarding establishment and maintenance of a communication path triggered by reception quality information included in the broadcast information, the number of relays, or a phenomenon such as detection of transmission failure to the other station. You may use together control of the communication route between the two. As a result, it is possible to avoid a situation in which the departure from the stable state due to reception failure of the broadcast information is delayed, and it is possible to cope with a change in the wireless communication state. Further, even when a transmission failure occurs in a state where there is no other effective wireless communication path, the user can continue communication by reducing the transmission rate.

  6A to 6C show an operation example of the counter unit 72 of FIG. 6A to 6C, the horizontal axis represents time, and the vertical axis represents the number of receptions. Here, at the timing when t is an integer, it is assumed that the reception unit 70 performs a process for receiving broadcast information from another base station apparatus. Also, here, only the number of receptions in a specific one base station apparatus is shown to simplify the description.

  First, FIG. 6A will be described. The receiving unit 70 has succeeded in receiving the notification information three times continuously at t = 0-2. Next, at t = 3, since the receiving unit 70 has not received the notification information, the counter unit 72 decreases the number of receptions by one. Thereafter, broadcast information is accepted at t = 4 and 7, and broadcast information is not accepted at t = 5 and 6, so the number of receptions at time t = 7 is 2.

  Next, FIG. 6B will be described. Here, description will be made assuming that the threshold value for shifting to the stability is 4 and the predetermined value is 1. The receiving unit 70 has succeeded in receiving the notification information four times continuously at t = 0-3. Here, since the number of receptions coincides with the threshold value of 4, the counter unit 72 sets 5 by adding a predetermined value to the number of receptions. Next, at t = 4 to 6, since the receiving unit 70 has not received the notification information three times in succession, the counter unit 72 reduces the total number of receptions by three. After that, since the number of receptions has reached the threshold value by continuously receiving the notification information at t = 7, 8, the counter unit 72 adds 5 to the number of receptions and sets it to 5.

  Further, FIG. 6C will be described. Here, the description will be made assuming that the threshold value for shifting to the stability is 4 and the predetermined value is 3. The receiving unit 70 has succeeded in receiving the notification information four times continuously at t = 0-3. Here, since the number of receptions coincides with the threshold value of 4, the counter unit 72 sets 7 by adding a predetermined value to the number of receptions. Next, since the receiving unit 70 has not received the notification information three times continuously at t = 4 to 6, the counter unit 72 reduces the total number of receptions by three. Thereafter, the accepting unit 70 accepts the notification information at t = 7. Here, since the number of receptions is 5 which is equal to or greater than the threshold value, in order to set the number of receptions to the maximum value, the counter unit 72 is a value obtained by adding a predetermined value 3 to the threshold value 4 That is, 7 is set as the number of receptions. Further, since the notification information is not continuously received at t = 8, 9, the counter unit 72 reduces the total number of receptions by two. Here, after t = 3, since the communication line with the base station apparatus has shifted to the stable state, it will be in an unstable state unless it fails to receive broadcast information four times or more in succession. Will not be transferred. In addition, even if the reception of the broadcast information fails, the counter unit 72 regards that the reception of the broadcast information is successful because the stability in the base station device can be trusted if the reception of the data signal is successful. The stable state may be maximized and the stable state may be continued.

  By taking the above aspects, a base station apparatus that can establish a highly stable communication path by a simple method can be realized. Specifically, it can operate without modifying the CSMA / CA method, which is an access control method for existing wireless LANs. This is because a device having an existing wireless LAN architecture can be easily realized only by software implementation. In this embodiment, the determination is made only based on the transmission / reception result of the notification information. Therefore, the desired effect can be obtained only by simple software processing. Furthermore, as an advantage of not modifying the CSMA / CA system, compatibility with a wireless LAN terminal that is operated in the same frequency band and wirelessly connected to the relay device can be maintained.

  These configurations described above can be realized in hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, it is realized by a program loaded in the memory. Describes functional blocks realized through collaboration. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 7 is a flowchart illustrating an operation example of the monitoring determination unit 62 of FIG. First, the receiving unit 70 receives the notification information notified from the receiving unit 54 (S10). Here, in the reception unit 70, when the notification information is received at a predetermined timing (Y in S10), the counter unit 72 increases the number of receptions that is stability (S12). Next, when the increased number of receptions is equal to or greater than the threshold value (Y in S14), the counter unit 72 sets a maximum value by adding a predetermined value to the number of receptions (S16). Furthermore, the route determination unit 74 determines that the wireless communication route to another base station device 30 that has notified the notification information is valid (S18).

  On the other hand, in S10, when the receiving unit 70 cannot receive the notification information at a predetermined timing (N in S10), the counter unit 72 decreases the number of receptions that is stability (S20). Next, if the decreased number of receptions is equal to or greater than the threshold value (Y in S22) and a data signal can be received instead of the broadcast information (Y in S23), the stability is continued. Therefore, the process proceeds to S16 and S18, and the wireless communication path is determined to be valid in order to continue relaying. On the other hand, even if the decreased number of receptions is equal to or greater than the threshold (Y in S22) and the data signal cannot be received (N in S23), the number of receptions becomes unstable. Since the conditions for shifting are not satisfied, at this stage, the route determination unit 74 determines that the wireless communication route is valid in order to continue the relay (S18).

  On the other hand, regardless of whether or not the receiving unit 70 receives the notification information at a predetermined timing, if the number of receptions is equal to or greater than the threshold (N in S14, N in S22), the notification information is notified. It is determined that the communication path between the base station apparatus and the base station apparatus has not yet been removed from the unstable state or has already shifted to the unstable state, and the path determination unit 74 performs relaying at this stage. Is not permitted, and the wireless communication path reaching the base station device 30 is determined to be invalid (S24). In S24, a process for selecting a new relay destination may be further performed. For example, the route determination unit 74 uses a reception quality information included in the broadcast information, the number of relays, or a phenomenon such as detection of a transmission failure to the partner station as a trigger to establish a more preferable communication route for establishing and maintaining a communication route. A base station apparatus that can be established may be selected as a relay destination, and the wireless communication path may be determined to be valid.

  As described above, the wireless communication path reaching the backbone base station apparatus 32 via the second relay base station apparatus 36 includes the second wireless communication path 620 and the third wireless communication path 630. Only when both wireless communication paths are valid, it is determined that the wireless communication path reaching the basic base station apparatus 32 via the second relay base station apparatus 36 is valid.

  FIG. 8 is a flowchart illustrating an operation example related to the validity determination of the wireless communication path of the control unit 60 of FIG. The flowchart illustrated in FIG. 8 may be started when the control unit 60 receives information on the validity of the wireless communication path from the monitoring determination unit 62.

  First, the control unit 60 confirms information regarding the validity of the wireless communication path received from the monitoring determination unit 62. Here, when the monitoring determination unit 62 determines the validity of the wireless communication path reaching the basic base station apparatus 32 via the second relay base station apparatus 36, the second wireless communication path 620 and the third wireless communication path 630 are determined. If any one of the routes is invalid, it is determined that the route via the second relay base station device 36 is invalid. If it is confirmed that the wireless communication path is invalid (Y in S30), the invalid information in the table indicating validity is updated (S32). Here, the invalid information is referred to and it is confirmed whether other wireless communication paths are invalid (S32). When it is confirmed that the other wireless communication paths are also invalid (Y in S34), the monitoring determination unit 62 is again confirmed as to whether there is any other valid wireless communication path. When the monitoring determination unit 62 cannot confirm the existence of a valid wireless communication path (N in S36), the control unit 60 sends a signal to the terminal device 40 that communication authentication is not permitted to the wireless communication unit 50. (S38). Further, the control unit 60 performs a setting to reject the authentication request from the terminal device 40.

  On the other hand, when the information regarding the validity of the wireless communication path received from the monitoring determination unit 62 indicates validity (N in S30), the control unit 60 permits authentication of communication with the terminal device 40 and causes the wireless communication unit 50 to communicate with the terminal. Communication with the device 40 is continued (S40). In addition, when the other wireless communication path is an effective path (N in S34), or when a separate effective wireless communication path is detected in the monitoring determination unit 62 (Y in S36), the control unit 60 permits authentication of communication with the terminal device 40, and causes the wireless communication unit 50 to continue communication with the terminal device 40 (S40).

  FIG. 9 is a flowchart showing an operation example when transmission failure is detected by the control unit 60 of FIG. The flowchart shown in FIG. 8 is started when the control unit 60 detects that the reception of the hello packet has failed or when it detects that the transmission of the data packet has failed. It may be triggered by the state of the current wireless communication path or other requirements.

  The control unit 60 determines whether or not the detected transmission failure has occurred in the wireless communication path on the backbone side (S50). The backbone side refers to a wireless communication path toward the backbone base station device 32 as viewed from the first relay base station device 34. Here, when the detected transmission failure has occurred in the wireless communication path on the backbone side (Y in S50), the first relay base station apparatus 34 refers to the table indicating the validity of the wireless communication path and switches It is confirmed whether there is a candidate (S54). When there is a switching candidate (Y in S54), the first relay base station apparatus 34 determines a wireless communication path to be switched, switches the path (S56), and ends the process.

  On the other hand, when there is no switching candidate (N in S54), the first relay base station apparatus 34 checks whether or not the transmission rate of the data signal being communicated is the lowest (S58). If the transmission rate of the data signal being communicated is the lowest (Y in S58), the wireless communication path on the backbone side is disconnected (S60), and the process ends. On the other hand, if the transmission rate of the data signal being communicated is not the lowest (N in S58), the transmission rate is lowered by one step (S62), and the process is terminated.

  In addition, when the detected transmission failure occurs in the wireless communication path on the branch line side instead of the trunk side (N in S50), the first relay base station apparatus 34 determines whether the transmission rate of the data signal being communicated is the lowest. (S64). If the transmission rate of the data signal being communicated is the lowest (Y in S64), the wireless communication path on the branch line side is disconnected (S66), and the process ends. On the other hand, if the transmission rate of the data signal being communicated is not the lowest (N in S64), the transmission rate is lowered by one step (S68), and the process is terminated.

  According to the present embodiment, a stable communication line can be constructed by executing relay control according to the number of receptions of broadcast information broadcast from other base station devices. In addition, because communication with the base station device that built the communication line is stable, a predetermined value is added to the number of receptions of the base station device, and backward protection is used to prevent unintentional disconnection of the communication line. And the communication network can be stabilized. In addition, when a control signal is accepted again while the number of receptions from other base station devices is larger than the threshold value, the stability of the base station device is increased by adding a predetermined value to the threshold value. By increasing the indicated number of receptions, the communication line can be protected backward. That is, unintentional disconnection of the communication line can be prevented, and the communication line network can be stabilized.

  In addition, a stable communication path can be established by preferentially adding a base station apparatus that has broadcast information with a small number of relays or a higher received electric field strength to the communication path. In addition to preventing disconnection of a communication path with a highly stable base station apparatus, establishing a more stable communication path by establishing a communication path with a base station apparatus having a small number of relays, etc. it can. In addition, the communication path of the entire system can be optimized. In addition, even if the notification information is not normally received from a highly stable base station apparatus that has already established a communication line, if the data signal can be received, the notification is made upon reception of the data signal. By determining that the information has been received, unintentional disconnection of the communication line can be prevented, and the communication line network can be stabilized.

  In addition, it is difficult to configure a path with a base station apparatus that is in a high load state in which a hidden terminal problem is likely to occur. Then, a route is established with a base station apparatus having a small communication load, the load of the entire system is distributed, and the occurrence of a hidden terminal problem can be reduced. Further, even when the communication load increases in a part of the communication path, it is possible to prevent inadvertent disconnection of the path. Further, since the processing is limited after the completion of the route configuration, it is possible to prevent the route configuration for the already high load route. In addition, since it is not necessary to execute complicated processing associated with data packet transmission such as RTS / CTS, the processing amount can be reduced. In addition, it is difficult to configure a route with a relay station that is in a high load state in which a hidden terminal problem is likely to occur. The operation is to connect a route with a relay station having a small communication load. The above effect can be realized without modifying the packet transmission method (CSMA / CA). Therefore, there is no need for hardware modification, and compatibility and flexibility can be maintained.

  In addition, when there is no valid wireless communication path, the terminal device transmits another relay base station device to the terminal device by transmitting a signal indicating that the terminal device does not authenticate communication with the relay base station device to the wireless communication unit. A trigger to search can be supplied. In addition, this enables the terminal device to execute communication with the relay base station device having an effective wireless communication path, so that a stable communication environment can be obtained. In addition, since communication is not performed with a relay base station apparatus having an invalid wireless communication path, it is possible to efficiently suppress the occurrence of useless communication.

  In addition, when broadcast information from other relay base station devices in the wireless communication path cannot be received continuously, the wireless communication path between the other relay base station device and the relay base station device is not effective. By determining, it is possible to efficiently suppress the occurrence of useless communication in the terminal device. Further, when the signal strength acquired based on the broadcast information from other relay base station devices in the wireless communication path is smaller than a predetermined threshold value, the other relay base station device and the relay base station device By determining that the wireless communication path between the terminals is not valid, it is possible to efficiently suppress occurrence of useless communication in the terminal device.

  Also, the effectiveness of the wireless communication path between the other relay base station apparatus and the basic base station apparatus in the wireless communication path is acquired based on the notification information from the other relay base station apparatus in the wireless communication path. By determining the validity of the wireless communication path to the basic base station apparatus via another base station apparatus based on the validity, it is possible to efficiently suppress the occurrence of useless communication in the terminal apparatus. In addition, when the broadcast information including information on the effectiveness of the wireless communication path between the backbone base station apparatus and the other relay base station apparatus cannot be continuously monitored, the information is transmitted via the other base station apparatus. By determining that the wireless communication path to the backbone base station apparatus is not effective, it is possible to efficiently suppress the occurrence of useless communication in the terminal apparatus. Even if it is determined that there is no effective wireless communication path, if another relay base station device that can be relayed to the basic base station device is detected by the monitoring determination unit, the terminal device A stable communication environment can be realized by continuing communication with the relay base station apparatus.

  In addition, when the state of the wireless communication path deteriorates, communication can be continued by switching to a wireless communication path different from the wireless communication path through which data signals are transmitted and received. Further, when there is no other wireless communication path to be switched to, the transmission rate used in the data communication unit is lowered to facilitate the continuation of communication in the wireless communication path in which communication is performed. Further, by lowering the transmission rate step by step, it is possible to stabilize the communication state while suppressing the transmission rate to the extent that the user does not feel uncomfortable. In addition, when there is no other effective wireless communication path, it is possible to suppress generation of useless communication by disconnecting communication with the terminal device.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the present embodiment, the communication system 100 has been described as a wireless LAN system. However, the present invention is not limited to this, and a system in which a relay device exists between the terminal device and the wired network network may be used. For example, an ad hoc communication system may be used. In addition, when the transmission failure of the hello packet is detected, the control unit 60 has been described as switching the route and changing the transmission rate. However, regardless of the presence or absence of the route, the control unit 60 determines the transmission rate of the data signal. May be lowered. In addition, the control unit 60 has been described as switching the route and changing the transmission rate in response to the transmission failure of the hello packet, but the received signal strength of the hello packet periodically measured by the monitoring determination unit 62 is The control unit 60 may execute path switching or transmission rate change when the threshold value to be invalidated is approached.

It is a figure which shows the structural example of the communication system concerning embodiment of this invention. It is a figure which shows the structural example of the 1st relay base station apparatus of FIG. 1, or a 2nd relay base station apparatus. It is a figure which shows the structural example of the alerting | reporting information which the radio | wireless communication part of FIG. 2 alert | reports. It is a figure which shows the example of the control table of the transmission rate in the control part of FIG. It is a figure which shows the structural example of the monitoring determination part of FIG. It is a figure which shows the operation example of the counter part of FIG. It is a flowchart which shows the operation example of the monitoring determination part of FIG. FIG. 3 is a flowchart illustrating an operation example according to the validity determination of the wireless communication path of the control unit in FIG. 2. FIG. 3 is a flowchart illustrating an operation example when a transmission failure is detected by the control unit of FIG. 2.

Explanation of symbols

  10 first server, 20 second server, 30 base station device, 32 backbone base station device, 34 first relay base station device, 36 second relay base station device, 40 terminal device, 50 radio communication unit, 52 generating unit, 54 reception unit 56 transmission unit 60 control unit 62 monitoring determination unit 64 wired communication unit 70 reception unit 72 counter unit 74 path determination unit 76 signal strength acquisition unit 100 communication system 200 wired network 300 Hello packet, 310 first header, 320 packet type, 330 second header, 340 control message, 400 control table, 600 wireless communication path.

Claims (1)

A data communication unit that transmits and receives data packets using any of a plurality of transmission rates via any one of at least one wireless communication path with a communication device to be communicated;
Wherein among the plurality of transmission rates, said a hello packet following the transmission rate transmission rate used for the data packet is used in the data communication unit, a hello packet for setting at least one wireless communication path, A Hello packet communication unit that transmits and receives data packets independently ;
Based on the hello packets sent and received in the hello packet communication unit, and a state monitoring unit data packet to monitor the status of the state to another wireless communication path of the wireless communication path to be transmitted and received,
When the state of the wireless communication path in which the data packet monitored based on the hello packet is transmitted / received deteriorates by the state monitoring unit, the wireless communication path different from the wireless communication path in which the data packet is transmitted / received, A path control unit that switches a wireless communication path through which data packets are transmitted and received,
The radio apparatus according to claim 1, wherein, when there is no other radio communication path, the path control unit lowers a transmission rate used based on data packets transmitted / received in the data communication unit .

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