JP2016052033A - Wireless communication system and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication system capable of dealing with communication failure between a base station and a center station.SOLUTION: In a wireless communication system where a plurality of wireless communication base stations and a plurality of center stations are connected via a switch, the switch has a communication propriety determination unit for determining propriety of communication with the center stations, and an instruction unit for notifying the wireless communication base stations of the information of a center station, not impossible of communication, as a transmission destination, when determination of the communication propriety determination unit is communication impossible. The wireless communication base station has a recording unit for recording the IP address of a center station, indicated by the information notified from the instruction unit as the transmission destination, as the transmission destination IP address, and a line interface for transmitting an IP packet of the transmission destination IP address recorded in the recording unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radio communication system and a control method thereof.

  In recent years, safety confirmation using a wireless communication system for a mobile phone or the like in the event of a disaster such as an earthquake and collecting information such as user injuries has become widespread. Generally, in a wireless communication system, a wireless base station (hereinafter referred to as a base station) is connected to a center station via a wired communication line, and if the communication line is disconnected due to a disaster, a failure occurs in communication from the mobile phone to the center station. And it will not be possible to confirm safety.

  For such a failure, for example, Patent Document 1 discloses that a base station that has a means for controlling transfer of a call as a relay station when a base station detects a disconnection with a telephone public network and that receives an outgoing call from a mobile phone. When the link with the telephone public network is broken, the station relays the outgoing call to the adjacent base station, and the forwarded call from the mobile phone is transferred to the base station connected to the base station controller. It is relayed and transferred, and communication connection with the telephone public network is performed from the base station controller via the switching center ”(summary).

JP 2000-050359 A

  If the technique described in Patent Document 1 is applied to a wireless communication system, the wireless communication system can be used even during a disaster. However, in order to relay between adjacent base stations in a communication area (also referred to as a cell), it is necessary to reduce the distance between base stations, that is, increase the number of base stations to increase the density of base stations. There is a problem that an increase in the number of stations requires a large equipment cost.

  Therefore, an object of the present invention is to provide a wireless communication system that can cope with a communication failure between a base station and a center station.

  A representative wireless communication system according to the present invention is a wireless communication system in which a plurality of wireless communication base stations and a plurality of center stations are connected via a switch. The switch determines whether communication with the center station is possible. A communication enable / disable determining unit, and an instruction unit for notifying the wireless communication base station of information on a center station that is not capable of communication as a transmission destination when the communication enable / disable determination unit determines that communication is not possible. The base station transmits a recording unit that records, as a transmission destination IP address, the IP address of the center station indicated by the information notified from the instruction unit as a transmission destination, and an IP packet of the transmission destination IP address recorded in the recording unit A line interface.

  The present invention is also grasped as a method for controlling a wireless communication system.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communications system which can respond to the communication failure between a base station and a center station can be provided.

It is a figure which shows the example of a structure of a radio | wireless communications system. It is a figure which shows the example of the IP packet communicated between a base station and a center station. It is a figure which shows the example of the communication confirmation sequence of a communication line. It is a figure which shows the example of the transfer sequence from a base station to a center station. It is a figure which shows the example of the transfer sequence from a center station to a base station. It is a figure which shows the example of the sequence of a line utilization rate suppression. It is a figure which shows the example of the restoration sequence of communication. It is a figure which shows the example of a structure of the radio | wireless communications system which has three center stations. It is a figure which shows the example of the sequence of line utilization rate suppression and a communication line selection. It is a figure which shows the example of the transmission sequence of IP packet dispersion | distribution in a communication line.

  In a wireless communication system such as a cellular phone, a base station is usually installed at a position away from other base stations in order to cover a wide communication area and to reduce equipment costs. On the other hand, when viewed across a plurality of communication companies, base stations of a plurality of communication companies may be close to a platform of a station or a rooftop of a high building. However, wireless communication often differs depending on the communication company, and relaying between base stations of different communication companies is difficult.

  On the other hand, a center station connected to a base station via a wired communication line is also installed relatively close when viewed across a plurality of communication companies, and the center station communicates with an IP (Internet Protocol) packet. Even a company center station can communicate. In an OSI (Open Systems Interconnection) reference model of a communication network, layer 3 (third layer) is a rule for end-to-end communication between networks, and communication based on an IP address is a standard. The IP packet includes information on the source IP address and the destination IP address called the L3 header at the beginning of the IP packet, and reaches the destination node from the source node on the network.

  A layer 3 switch (hereinafter referred to as an L3 switch) is a device that relays IP packets based on an IP address. Therefore, by connecting a wireless station and a center station of different communication companies with an L3 switch, it is possible to send and receive IP packets to each other and to pass through the center stations of other communication companies only by rewriting the IP address. In particular, when a failure such as disconnection occurs in the backhaul line between the L3 switch and the center station, the backhaul line with the center station of another communication company can be used. In addition, when a communication path of another communication company is used as a part of the communication path, so-called tunneling technology that encapsulates with a packet of another communication company is generally used. The use of the communication path of the telecommunications company can be realized with a simple structure.

  A plurality of telecommunications companies and different telecommunications companies are examples, and the telecommunications company is not limited in terms of capital. The wireless communication system only needs to be configured such that a plurality of base stations and a center station are installed so that the plurality of base stations and the center station can be connected by an L3 switch, and communication is possible using IP packets. In addition, each of the L3 switch, the base station, and the center station includes a processor, and the processor may execute a program and firmware, or may include both the processor and a dedicated hardware circuit. It may be a wear circuit. The program and firmware may be written when the L3 switch, the base station, and the center station are manufactured, or may be written after a network or a dedicated jig is connected after installation.

  Further, the program and firmware may be stored in a RAM (Random Access Memory), flash memory, SSD (Solid State Drive), HDD (Hard Disk Drive) recording unit, and the recording unit may store data. The structure of data stored in the recording unit may be a table or a list, or another data structure.

  Hereinafter, preferred embodiments will be further described with reference to the drawings.

  First, the configuration of the wireless communication system will be described with reference to FIG. The wireless communication system includes base stations A110 and B120, which are wireless communication base stations owned by different communication companies, and the base station A110 and the base station B120 are connected to the L3 switch 130. The L3 switch 130 is connected via a backhaul line 140 to center stations owned by different communication companies, that is, the center station A 150 and the center station B 160, and has a control unit 132 therein. It is preferable that the base station A110, the base station B120, the center station A150, and the center station B160 are densely packed in one station or one building because the connection with the L3 switch 130 is easy.

  The control unit 132 can issue instructions to the base station and the center station, and controls IP packets. Each center station is connected to the IP network 170. In a normal state where the backhaul line 140 is free of trouble, the base station A110 of company A communicates with the center station A150 of company A via the L3 switch 130, and the base station B120 of company B passes through the L3 switch 130. To communicate with the center station B 160 of company B. When a failure occurs in the backhaul line 140 and communication becomes impossible, the L3 switch 130 changes the route and relays the IP packet between the base station and the center station of different communication companies.

  Base station A110 transmits and receives radio signals to and from portable terminals (not shown) by antennas 117 and 118. The antenna 117 and the antenna 118 may be antennas for different frequencies, may be so-called diversity antennas, and are antennas for MIMO (Multiple-Input Multiple-Output) or beamforming. Also good. However, the number of antennas is not limited to two, but may be one or three or more. The radio signal transmission / reception unit 111 performs amplification of the radio signal and conversion between the radio signal and the baseband signal. The modem unit 112 performs baseband signal modulation processing and demodulation processing.

  The packet assembling unit 113 assembles an IP packet described with reference to FIG. In this assembly, the packet assembly unit 113 sets information necessary for transmission of the IP packet, such as an IP address, in the IP packet based on an instruction from the control unit 114. The control unit 114 is a circuit that controls the entire base station A110, and can be realized by a so-called processor or the like that controls others. The destination IP recording unit records an address for transmitting the IP packet to the center station A 150 and the center station B 160 based on an instruction from the control unit 114. A line IF (Interface) 116 is connected to the L3 switch 130, and transmits and receives IP packets of wired signals.

  The base station B120 has the same structure as the base station A110. The example of the wireless communication system illustrated in FIG. 1 includes two base stations A110 and B120, but three or more communication companies may include three or more base stations. A communication company may have two or more wireless stations and perform handoff of wireless communication with a portable terminal.

  The L3 switch 130 is a packet switch that connects the base station A110 and the base station B120 to the center station A150 and the center station B160. The L3 switch 130 includes a switch unit 131 that relays IP packets between designated lines and a control unit 132. Here, since the switch unit 131 is the same as a general packet switch circuit, the description thereof is omitted. The control unit 132 is a circuit that issues instructions to the base station A110, the center station A150, and the center station B160 in accordance with the state of communication in the wireless communication system.

  Based on the communication confirmation communication with the connected center station A150 and center station B160, the communication availability determination unit 133 can communicate without disconnecting the communication lines between the center station A150 and the center station B160. It is determined whether or not there is. The line usage rate determination unit 134 receives line usage rate information from each of the center station A 150 and the center station B 160, and determines whether or not it is necessary to suppress the line usage rate. The instruction unit 135 instructs the base station A 110, the center station A 150, and the center station B 160 using the information stored in the recording unit 136 based on the results determined by the communication availability determination unit 133 and the line usage rate determination unit 134. The instruction unit 135 can be realized by a so-called processor for instructing others.

  The recording unit 136 records a failure determined by the communication availability determination unit 133 and the like in association with a countermeasure according to the failure. The recording unit 136 records information for communicating with each base station and each center station, including information such as which communication line of the line IF 137 each of the plurality of base stations and center stations is connected to. May be. The line IF 137 is a circuit that is connected by wire to the base station A110, the base station B120, the center station A150, and the center station B160 so that they can communicate with each other by IP packets. By the operation of the switch unit 131, the line IF 137 transfers the IP packet to the communication line corresponding to the destination address of the received IP packet. In addition, the line IF 137 transmits the instruction information of the instruction unit 135 to the base station A110 or the like, or receives information on the line usage rate from the center station A150 or the like.

  The center station A 150 controls communication between the portable terminal and the IP network 170. The handoff control unit 151 of the center station A150 may control IP packet exchange at the time of handoff between a plurality of center stations of the same communication company, or may control the base station at the time of handoff between adjacent base stations of the same communication company. May be. The user authentication function unit 152 authenticates the user of the mobile terminal and manages billing. The communication availability determination unit 154 corresponds to the communication availability determination unit 133 of the L3 switch 130 and, based on communication confirmation, determines whether the communication line between the L3 switch 130 is disconnected and communication is possible. judge.

  The network management unit 155 monitors a failure and controls a network connected to the center station A 150. Based on an instruction from the L3 switch 130 or a determination result of the communication availability determination unit 154, an acceptance recording unit Information is recorded in 156 or information in the other center recording unit 153 is referred to. The network management unit 155 may perform management and control in communication between the mobile terminal and the IP network 170, and can be realized by a so-called processor that manages and controls others.

  The other center recording unit 153 records in advance the IP address of, for example, the center station B160, which is a center station of another communication company. The recorded IP address is used to transfer an IP packet to a center station of another communication company. The other center recording unit 153 does not need to record the IP addresses of all the center stations of other communication companies, and may record only the IP address of the center station used as the transfer destination. Based on an instruction from the L3 switch 130, the reception recording unit 156 records the IP address of the base station B120 and the IP address of the center station B160, which are base stations of other communication companies, so that communication from other communication companies is accepted. . The recorded IP address is used to transfer an IP packet from the base station of another communication company to the center station.

  The line IF 157 is a circuit that performs wired connection so that IP packets can be communicated between the L3 switch 130 and the IP network 170. Since the center station B160 has the same structure as the center station A150, illustration and description of the structure are omitted. The example of the wireless communication system shown in FIG. 1 has two center stations A150 and B160. However, three or more communication companies may have three or more center stations. A company may have more than one center station.

  For example, as shown in FIG. 1, when the backhaul line 140 is disconnected between the L3 switch 130 and the center station A150, the L3 switch 130 and the center station B160 communicate, and the center station B160 and the center station A150 are connected. By communicating via the IP network 170, the base station A110 and the center station A150 can communicate.

  Next, an IP packet will be described with reference to FIG. The IP packet has a portion storing information related to transmission of an IP packet called an L3 header at the head, and the L3 header has a transmission source IP address 201 and a transmission destination IP address 202 in particular. The destination of the IP packet is changed by changing the destination IP address 202. The IP packet has a data part at the rear, and the data part has base station information 203 and data 204. The base station information 203 holds information indicating from which base station the IP packet is transmitted or to which base station. Data 204 is a data body such as safety information to be transmitted.

  The IP packet transmitted from the base station A110 to the center station A150 goes from the base station A110 to the L3 switch 130 and from the L3 switch 130 to the center station A150 during normal operation. The configuration of this IP packet is as shown in packet A1 in FIG. Since the L3 switch 130 does not change the configuration of the IP packet, the L3 switch is omitted in FIG. The source IP address 201 of the packet A1 is the IP address of the base station A110, and the destination IP address 202 is the IP address of the center station A150. The content of the base station information 203 is information indicating the base station A110.

  For example, when a failure occurs in a part of the backhaul line 140 between the L3 switch 130 and the center station A150 and communication becomes impossible, the IP packet transmitted from the base station A110 has the configuration of the packet A2. In this configuration, the destination IP address 202 is changed from the IP address of the center station A150 of the packet A1 to the IP address of the center station B160. By changing the destination IP address 202, it becomes possible to transmit an IP packet to the center station B 160 using a communication line different from a part of the backhaul line 140 where the failure has occurred.

  The IP packet received by the center station B 160 is transmitted to the center station A 150 via the IP network 170. The IP packet transmitted at that time has a packet A3 configuration. In this configuration, the destination IP address 202 is changed from the IP address of the center station B160 of the packet A2 to the IP address of the center station A150. The configuration of the packet A3 received by the center station A150 is the same as the configuration of the packet A1 transmitted from the base station A110 during normal operation.

  The configuration of the IP packet transmitted from the center station A150 to the base station A110 is like the packet B1 during normal operation. The source IP address 201 is the IP address of the center station A 150, and the destination IP address 202 is the IP address of the base station A 110. The content of the base station information 203 is information indicating the base station A110. When a failure occurs in a part of the backhaul line 140 between the L3 switch 130 and the center station A 150 and communication becomes impossible, an IP packet transmitted from the center station A 150 to the center station B 160 via the IP network 170 is The packet B2 is configured.

  In the configuration of the packet B2, the transmission destination IP address 202 is changed from the IP address of the base station A110 of the packet B1 to the IP address of the center station B160. The IP packet received by the center station B160 is transmitted to the base station A110. The IP packet transmitted at this time has a packet B3 configuration. In this configuration, the destination IP address 202 is changed from the IP address of the center station B160 of the packet B2 to the IP address of the base station A110. The configuration of the packet B3 received by the base station A110 is the same as the configuration of the packet B1 transmitted from the center station A150 during normal operation.

  With reference to FIG. 3, a communication confirmation sequence when a disaster occurs will be described. During normal operation, the base station A 110 and the center station A 150 transmit and receive IP packets via the L3 switch 130. For example, the base station A 110 generates an IP packet 302 that is a packet A 1 by the IP packet processing 301 from the wireless packet received from the mobile terminal, and transmits the packet to the L3 switch 130. Based on the fact that the destination IP address 202 of the packet A1 is the IP address of the center station A150, the L3 switch 130 transmits the received IP packet 302 to the center station A150 as it is. The center station A 150 executes IP packet processing 303 which is processing for safety confirmation and processing for further transfer to the IP network 170.

  For example, the center station A 150 generates an IP packet 305 that is a packet B 1 and transmits it to the L3 switch 130 by an IP packet process 304 that is a process related to safety confirmation and a process for transferring a packet received from the IP network 170. Based on the fact that the destination IP address 202 of the packet B1 is the IP address of the base station A110, the L3 switch 130 transmits the received IP packet 305 as it is to the base station A110. Base station A110 executes IP packet processing 306 for transmission to the mobile terminal.

  A communication confirmation 307 is transmitted / received between the center station A 150 and the center station B 160 and the L3 switch 130. The communication confirmation 307 may be a special packet passing through the same communication line as the IP packet, or a simple signal. Instead of the communication confirmation 307, a signal such as ACK (Acknowledgement) or NAK (Negative Acknowledgment) that is a response to the IP packet 302 or the IP packet 305 may be used. The communication confirmation 307 is transmitted / received at a predetermined cycle or with a specific event such as a disaster or maintenance work.

  In response to the communication confirmation 307, the communication capability determination unit 154 of the center station A 150 executes determination 308 regarding whether communication is possible. If it is determined in the determination 308 that the communicability determination unit 154 determines that communication is possible, that is, if YES, the operation is continued as it is. If it is determined in the determination 308 that the communicability determination unit 154 is not communicable, that is, NO, the network management unit 155 in the destination change 309 causes the network station B160 of another communication company recorded in the other center recording unit 153 in advance. Change the destination IP address to the IP address.

  In response to the communication confirmation 307, the communication availability determination unit 133 of the L3 switch 130 executes a determination 310 whether or not communication is possible. If it is determined in the determination 310 that the communication enable / disable determination unit 133 is communicable, that is, if YES, the operation is continued as it is. If it is determined in the determination 310 that the communication enable / disable determination unit 133 is not communicable, that is, NO, the instruction unit 135 transmits a transmission destination change notification 311 to the base station A 110 based on the information stored in the recording unit 136. The control unit 114 of the base station A 110 that has received the transmission destination change notification 311 changes the recording of the transmission destination IP address of the transmission destination IP recording unit 115 in the transmission destination change 312.

  Further, the instruction unit 135 transmits a registration notification 313 to the center station B 160 based on the information stored in the recording unit 136. The network management unit 155 of the center station B 160 that has received the registration notification 313 registers with the reception recording unit 156 of the center station B 160 by the reception registration 314. Note that the base station A 110 and the center station B 160 may transmit a completion notification to the L3 switch 130 after completion of the transmission destination change 312 and the acceptance registration 314, respectively.

  Here, in the recording unit 136 of the L3 switch 130, a failure content indicating that communication with the center station A 150 is not possible and a countermeasure for the failure are recorded in association with each other. For example, for this failure content, the base station A110 changes the transmission destination of the IP packet from the center station A150 to the center station B160, the center station B160 accepts the base station A110 and the center station A150, and the base station A110 A measure of registering the transfer of the IP packet to the center station A 150 is recorded. These countermeasure contents are notified by a transmission destination change notification 311 and a registration notification 313.

  The recording unit 136 may record a failure content indicating that communication with the center station B 160 is not possible and a countermeasure for the failure in association with each other. For example, for this failure content, the base station B120 changes the IP packet transmission destination from the center station B160 to the center station A150, the center station A150 accepts the base station B120 and the center station B160, and the base station B120 A measure of registering the transfer of the IP packet to the center station B 160 may be recorded.

  When a disaster occurs and the communication line between the L3 switch 130 and the center station A 150 is disconnected on the backhaul line 140, the determinations 308 and 310 are determined by the communication confirmation 307 as not possible to communicate as in the sequence described above. The wireless communication system prepares for communication described below.

  With reference to FIG. 4, a sequence in which an IP packet reaches from the base station A110 to the center station A150 when the communication line between the L3 switch 130 and the center station A150 is disconnected will be described. For example, when the base station A110 receives a wireless packet from a portable terminal, the base station A110 executes an IP packet processing 401 for transmission to the center station A150. In the IP packet processing 401, when assembling the IP packet based on the wireless packet received from the mobile terminal, the packet assembling unit 113 reads the IP address of the center station B 160 changed by the transmission destination change 312 from the transmission destination IP recording unit 115. , The destination IP address 202 of the IP packet is set. The IP packet 402 that has become packet A2 by this setting is transmitted from the line IF 116.

  The L3 switch 130 that has received the transmitted IP packet 402 transmits the IP packet 402 to the center station B 160 according to the transmission destination IP address 202. When the center station B 160 receives the IP packet 402, the network management unit 155 of the center station B 160 acquires the base station information 203 of the IP packet 402 through the base station information acquisition 403. If the base station information 203 is information indicating the base station B120, and the IP packet is transmitted by the base station B120, the determination 404 is YES, and the center station B160 in the IP packet processing 408 performs normal operation for the base station B120. Process.

  In the example of FIG. 4, since the base station A110 transmits the IP packet 402, and the base station information 203 is information indicating the base station A110, the determination 404 is NO. Then, in the transmission destination IP address change 405, the center station B 160 changes the transmission destination IP address 202 of the IP packet 402 to the IP address of the center station A 150 according to the information recorded in the reception recording unit 156. The center station B 160 transmits to the IP network 170 the IP packet 406 that has become packet A3 due to the change of the IP address. The IP packet 406 reaches the center station A 150 from the IP network 170 according to the IP address of the center station A 150 set as the transmission destination IP address 202.

  Here, since the IP packet 406 is the packet A3 and is the same as the packet A1, the IP packet processing 407 is the same as the processing of the packet A1 during normal operation. In addition, when the center station A 150 receives the IP packet 406, the user authentication function unit 152 of the center station A 150 can manage charging of the IP packet without omission.

  With reference to FIG. 5, a sequence in which an IP packet arrives from the center station A150 to the base station A110 when the communication line between the L3 switch 130 and the center station A150 is disconnected will be described. Each of the IP packet processing 501 to IP packet processing 508 is basically processing corresponding to the IP packet processing 401 to IP packet processing 408 described with reference to FIG. For example, when the center station A150 receives an IP packet received from the IP network 170, the center station A150 executes an IP packet processing 501 for transmission to the base station A110. The network management unit 155 of the center station A 150 sets the IP address of the center station B 160 changed in the transmission destination change 309 to the transmission destination IP address 202, and the center station A 150 sends the IP packet 502 that is the packet B2 to the IP network 170. Send.

  The IP packet 502 reaches the center station B 160 according to the IP address of the center station B 160 of the transmission destination IP address 202. When the center station B 160 receives the IP packet 502, the network management unit 155 of the center station B 160 acquires the base station information 203 of the IP packet 502 through the base station information acquisition 503. Since the base station information 203 has not been changed by the IP packet processing 501, the base station information 203 is information indicating the base station A110. Therefore, the determination 504 is NO, and the center station B 160 changes the destination IP address 202 of the IP packet 502 to the IP address of the base station A 110 according to the information recorded in the reception recording unit 156 when the destination IP address is changed 505. change. The IP packet 506 that has become packet B3 due to the change of the IP address reaches the base station A110 via the L3 switch 130, and the base station A110 can perform the IP packet processing 507.

  By acquiring the base station information 203 from the IP packet, the center station B 160 can easily determine that it is not an IP packet related to the base station B 120 during normal operation. Then, the center station B 160 determines whether the transmission destination address 202 is the IP address of the center station A 150 or the IP address of the base station A 110 according to whether the transmission source address 201 is the IP address of the base station A 110 or the IP address of the center station A 150. Can be changed. The base station information 203 may include information on the direction of an IP packet to the base station or an IP packet from the base station, and may include information on this direction in addition to the base station information 203. When the base station information 203 includes direction information, the center station B 160 can more easily determine which IP address of the transmission destination IP address 201 is to be changed.

  With reference to FIG. 6, the sequence when the communication line between the L3 switch 130 and the center station A 150 is disconnected will be further described. In the description using FIG. 3, when a disconnection is detected, a detour route using the center station B 160 is set. However, since the center station B 160 is not originally installed for the base station A 110 of another communication company, There is also a possibility that the line usage rate overflows. Therefore, this example suppresses the line usage rate of the center station B160 and enables detouring using the center station B160.

  Between the determination 310 described with reference to FIG. 3 and the transmission destination change notification 311, an inquiry 601 to a suppression completion 606 are added. If it is determined at decision 310 that the L3 switch 130 is not communicable, that is, NO, the line usage rate determination unit 134 transmits a line usage rate inquiry 601 to the center station B 160. In response to the inquiry 601, the center station B 160 transmits a line usage rate response 602 to the L3 switch 130. Here, the line usage rate may be any value as long as the value indicates the highest usage rate of the line shared in the operation of relaying the IP packet between the base station A110 and the center station A150 by the center station B160. Good.

  The line usage rate determination unit 134 of the L3 switch 130 executes determination 603 as to whether the received line usage rate exceeds 90%. If it is determined that the line usage rate exceeds 90%, that is, YES, the instruction unit 135 of the L3 switch 130 transmits an instruction 604 for suppressing the line usage rate to the center station B 160. The line usage rate suppression instruction 604 may include a line usage rate value that is the target of suppression. The value of the line usage rate may be set in advance based on an agreement between communication companies, or may be a value based on a predetermined calculation between the response 602 of the line usage rate and a preset value. On the other hand, the center station B 160 executes line usage rate suppression 605.

  The line usage rate suppression 605 may be suppression by flow control of the center station B160 in transmission / reception of IP packets with the base station B120, or the center station B160 forwards the suppression 605 to the base station B120, and the IP with the center station B160. Suppression by flow control of the base station B120 in transmission / reception of packets may be performed, or suppression by flow control of the base station B120 in transmission / reception of radio packets with mobile terminals may be used. These suppressions may be controlled by the network management unit 155. The flow control may be, for example, a window size control that is already widely known and used. When the suppression is completed, a line usage rate suppression completion 606 is transmitted to the L3 switch 130. On the other hand, the L3 switch 130 transmits a transmission destination change notification 311 to the base station A110, and the sequence is as described with reference to FIG.

  With reference to FIG. 7, the sequence of the logical communication recovery after the physical disconnection of the communication line is recovered will be described. Even after the communication confirmation 307 described with reference to FIG. 3, the communication confirmation 701 is transmitted according to a predetermined cycle or a specific event occurrence. For example, the communication confirmation 701 may be transmitted in response to the occurrence of a specific event such as a manual operation by maintenance personnel when a broken communication line is repaired. In response to the communication confirmation 701, the communication capability determination unit 154 of the center station A 150 executes a determination 702 as to whether communication is possible. In this example, since the disconnection of the communication line has been restored, it is determined in the determination 702 that the communication enable / disable determination unit 154 is communicable, that is, YES, and in the transmission destination change 703, the network management unit 155 of the center station A 150 The address is changed to the IP address of the base station A110. As a result, the center station A 150 returns the destination IP address to the IP address before the occurrence of the disaster.

  The communication determination unit 133 of the L3 switch 130 also executes a determination 704 as to whether or not communication with the communication confirmation 701 is possible. In this example, since the disconnection of the communication line has been recovered, the communication availability determination unit 133 determines in step 704 that communication is possible, that is, determines YES, and transmits a release notification 705 to the center station B160. Receiving the cancellation notice 705, the center station B 160 executes the acceptance cancellation 706, and deletes the record registered in the acceptance recording unit 156 by the acceptance registration 314. If the line usage rate is suppressed, the suppression may be released.

  Also, the L3 switch 130 transmits a release notification 707 to the base station A110. The control unit 114 of the base station A 110 that has received the release notification 707 executes the transmission destination change 708, and records the changed transmission destination IP address of the transmission destination IP recording unit 115 in the transmission destination change 312. Change to address. As a result, the base station A110 returns the destination IP address to the IP address before the occurrence of the disaster.

  As explained above, even if a part of the backhaul line is disconnected due to the occurrence of a disaster, the disconnection is detected and a detour route is set using the backhaul line and center station of another communication company. It is possible to continue the wireless communication service. Further, by suppressing the line usage rate when the detour route is set, the detour route can be used reliably.

  The first embodiment is an example in which only one detour route exists, but the second embodiment is an example in which a detour route is selected and used based on the line usage rate when there are two or more detour routes. is there. Therefore, an example of three center stations and three base stations by three communication companies will be described with reference to FIG.

  The base station A110, base station B120, L3 switch 130, center station A150, center station B160, and IP network 170 are as described above. The wireless communication system of this example further includes a base station C801 and a center station C802, the L3 switch 130 and the center station C802 are connected by a backhaul line 140, and the center station C802 and the IP network 170 are also connected by a communication line.

  For this reason, when the communication line of the backhaul line 140 between the L3 switch 130 and the center station A150 is disconnected due to the occurrence of a disaster, in addition to the thin hatched arrow having the center station B160 as a detour path already described, There is also a detour route using the center station C802 with a dark hatched arrow, and two detour routes are to be selected.

  With reference to FIG. 9, a sequence for selecting from two detour paths will be described. Similar to the description using FIG. 6, an inquiry 901 to a selection 907 are added between the determination 310 and the transmission destination change notification 311. If the L3 switch 130 determines in the determination 310 that communication is not possible, that is, NO, the L3 switch 130 transmits a line usage rate inquiry 901 to both the center station B 160 and the center station C 802. In response to the inquiry 901, each of the center station B 160 and the center station C 802 transmits a line usage rate response 902 to the L3 switch 130.

  The L3 switch 130 suppresses the line usage rates of the center station B 160 and the center station C 802 based on the received line usage rates. The determination 603 to the response 606 are the same as already described with reference to FIG. 6, and the determination 903 to the response 906 are the same as the determination 603 to the response 606 with the suppression target changed to the center station C802. The L3 switch 130 executes the selection 907 of the center station B 160 and the center station C 802 with the lower line usage rate, and sets the destination change notification 311 as the destination IP address so as to set the IP address of the selected center station as the destination IP address. Transmit to station A110.

  In the above description, when the line usage rate exceeds 90% in both the determination 603 and the determination 903, the line usage rate is suppressed in both the center station B160 and the center station C802, but the center station that is not selected in the selection 907 is The suppression may be released. The line usage rate inquiry 901 may be transmitted for any unit of communication. For example, the line usage rate inquiry 901 may be transmitted only once for the NO of the determination 310, or the line usage rate inquiry 901 is transmitted each time a predetermined number of IP packets after the NO of the determination 310 pass. Each time, the selection 907 may be executed and the transmission destination change notification 311 may be transmitted. Further, in a wireless communication system having four or more center stations, the L3 switch may execute selection 907 for three or more selection targets.

  As described above, it is possible to select a bypass route with a low line usage rate from among a plurality of bypass routes, and to suppress the influence on the communication line providing the bypass route to a low level, as well as communication using the bypass route. Many communication lines can be used.

  The second embodiment is an example in which one bypass route is selected and used based on the line usage rate, but the third embodiment is an example in which two or more bypass routes are selected and used. For this reason, an example in which two or more bypass routes are selected so as to distribute IP packets regardless of the line usage rate will be described with reference to FIG. For example, in the wireless communication system shown in FIG. 8, the first IP packet is transmitted via the center station B160, the second IP packet is transmitted via the center station C802, and the third IP packet is transmitted to the center station B160. The IP packet is transmitted using the communication lines that are not disconnected in order, such as being transmitted via the station B160.

  The transmission destination IP recording unit 115 of the base station A110 records a plurality of IP addresses in order as the transmission destination IP address, the IP address of the center station B160 and the IP address of the center station C802. The control unit 114 of the base station A 110 executes the first acquisition 1001 of the IP address recorded in the transmission destination IP recording unit 115 and sends the acquired IP address to the packet assembly unit 113. The packet assembling unit 113 executes setting 1002 for the destination IP address 202, and the line IF 116 executes transmission 1003 of the set IP packet.

  The control unit 114 executes a determination 1004 on whether there is a next IP address in the transmission destination IP recording unit 115. If it is determined that there is a next IP address, the control unit 114 executes a next IP address acquisition 1005. Return to the execution of the setting 1002. When it is determined that there is no next IP address as a result of the execution of the determination 1004, the control unit 114 returns to the execution of the acquisition 1001.

  The transmission destination IP recording unit 115 records the line usage rate of each center station together with the transmission destination IP address. In the acquisition 1001 and acquisition 1005, the control unit 114 also acquires the line usage rate, and the line usage rate is predetermined. Only the IP address of the center station that does not exceed the value may be set in the setting 1002.

  As described above, it is possible to transmit IP packets by distributing a plurality of bypass routes, avoiding a state of placing a burden on a specific bypass route, and suppressing the influence on the communication line providing the bypass route to a low level. be able to.

  As described above, the wireless communication system that can communicate at the time of a disaster has been described using the first to third embodiments. However, not only in the case of a disaster, but also when a failure occurs in the communication line between the base station and the center station for some reason. Thus, a wireless communication system that can handle a detour route can be provided.

110 Base station A
120 Base station B
130 L3 switch 140 Backhaul line 150 Center station A
160 Center station B
170 IP network

Claims (10)

In a wireless communication system that connects a plurality of wireless communication base stations and a plurality of center stations via a switch,
The switch is
A communication availability determination unit that determines whether communication with the center station is possible;
When the communication enable / disable determining unit determines that communication is not possible, an instruction unit that notifies the wireless communication base station of information on a center station that is not capable of communication as a transmission destination;
The wireless communication base station is
A recording unit for recording, as a transmission destination IP address, the IP address of the center station indicated by the information notified as the transmission destination from the instruction unit;
A wireless communication system comprising: a line interface that transmits an IP packet of a transmission destination IP address recorded in the recording unit. The switch indicating unit is:
When communication by the communication enable / disable determining unit of the switch is not possible, the center station determined to be incapable of communication and the notified wireless communication base station are registered as notification targets to the center station that is not incapable of communication. ,
The center station
A recording unit for recording acceptance of the center station and the radio communication base station that are the targets of the registration;
When acceptance is recorded in the recording unit of the center station, the wireless communication base station where the acceptance is recorded changes the destination IP address of the destination IP packet to the IP address of the wireless communication base station where the acceptance is recorded A network management unit for changing the destination IP address of the destination IP packet to the IP address of the center station where the acceptance is recorded by the center station where the acceptance is recorded;
The wireless communication system according to claim 1, further comprising: a line interface that transmits an IP packet whose IP address has been changed by the network management unit. The center station
A communication availability determination unit that determines whether communication with the switch is possible;
A recording unit that records an IP address of a center station that is not incapable of communication as a transmission destination in a case where communication by the communication station is not possible.
The network management unit of the center station
When the communication enable / disable determining unit of the center station determines that communication is not possible, the wireless communication base station records the destination IP address of the destination IP packet in the center station's non-communicable center station IP address recorded in the center station recording unit The wireless communication system according to claim 2, wherein the wireless communication system is changed to: The IP packet has base station information separately from the destination IP address,
The network management unit of the center station
The wireless communication system according to claim 3, wherein a destination of the IP packet is determined based on the base station information. The switch is
A line usage rate determination unit that acquires the line usage rate of the center station and determines whether the acquired line usage rate exceeds a predetermined value;
The switch indicating unit is:
When it is determined by the line usage rate determination unit that the line usage rate exceeds a predetermined value, the center station is notified of the suppression of the line usage rate,
The network management unit of the center station
The wireless communication system according to claim 4, wherein the line usage rate is suppressed based on the notification of the suppression of the line usage rate. The switch indicating unit is:
6. The center station having the lowest line usage rate acquired from the plurality of center stations is selected, and information on the selected center station is notified to the radio communication base station as a transmission destination. Wireless communication system. The line interface of the wireless communication base station is
6. The wireless communication system according to claim 5, wherein an IP packet in which a plurality of IP addresses recorded in a recording unit of the wireless communication base station are sequentially set as transmission destination IP addresses is transmitted. A control method of a radio communication system for connecting a plurality of radio communication base stations and a plurality of center stations via a switch,
The switch is
Determine whether communication with the center station is possible,
If the determination is impossible communication, information of the center station that is not in communication is notified to the wireless communication base station as a transmission destination,
The wireless communication base station is
Record the IP address of the center station notified as the destination as the destination IP address,
A control method characterized by transmitting an IP packet of the recorded destination IP address. The switch is
If the determination is not possible to communicate, the center station determined to be incapable of communication and the instructed wireless communication base station as registration targets are notified to the center station that is not incapable of communication,
The notified center station that is not incapable of communication is:
Record the acceptance of the center station and the radio communication base station subject to the registration,
The wireless communication base station in which the acceptance is recorded changes the destination IP address of the destination IP packet to the IP address of the wireless communication base station in which the acceptance is recorded, and the center station in which the acceptance is recorded is the destination IP address. Change the destination IP address of the packet to the IP address of the center station where the acceptance was recorded,
The control method according to claim 8, wherein the IP packet with the changed IP address is transmitted. The center station
Determine whether communication with the switch is possible,
When it is determined that communication with the switch is not possible, the wireless communication base station changes the destination IP address of the destination IP packet to the IP address of the center station that is recorded as the destination and is not capable of communication. The control method according to claim 9.

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