JP5972496B1 - base station - Google Patents

Abstract

A base station in a mobile communication system, comprising: a mobile station connected to a terminal device; a plurality of base stations that perform radio communication with the mobile station; and a transfer device that transmits data addressed to the terminal device to the base station. A storage unit 32 that stores information on mobile stations that can wirelessly communicate with each other and information on a connection relationship between the terminal device and the mobile station, and confirms a destination terminal device of data received from the transfer device, and stores it in the storage unit 32 If the mobile station to which the destination terminal device is connected is a mobile station capable of wireless communication with the own station, the control unit 31 that transmits the received data to the communication area of the own station; Is provided.

Description

  The present invention relates to a base station and a transfer apparatus that communicate with a mobile station that moves on a predetermined route.

  2. Description of the Related Art Conventionally, there is a mobile communication system in which a mobile station moving on a predetermined route performs communication by performing handover between a plurality of base stations arranged along the moving route. In order to suppress packet loss when a mobile station performs handover, a packet transmission source device transmits a packet by bicast to the handover source base station and the handover destination base station before the mobile station performs handover Is being considered.

  For example, Patent Document 1 discloses a broadcast transmission technique in which a home agent transfers a packet addressed to a mobile terminal to an access router to which the mobile terminal is currently connected and a handover destination access router. Patent Document 2 discloses a technique in which a radio network control device transmits a radio resource control message by bicast to a mobile station through a current serving cell and a handover target cell while the mobile station performs a handover. .

Japanese Patent No. 4397397 Japanese Patent No. 5001277

  However, according to the above conventional technique, when a device that transmits a packet to a mobile station via a base station transmits a packet to a handover destination base station before the mobile station connects, the handover destination base station A packet is transmitted in a cell. For this reason, there is a problem in that the radio baseband is compressed at the handover destination base station and the system throughput is reduced.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a base station capable of reducing a decrease in system throughput while suppressing a loss of user data when a mobile station performs a handover.

  In order to solve the above-described problems and achieve the object, the present invention transmits a mobile station connected to a terminal device, a plurality of base stations that perform radio communication with the mobile station, and data addressed to the terminal device to the base station. The base station in a mobile communication system provided with the transfer apparatus which performs. The base station includes a storage unit that stores information on a mobile station capable of wireless communication with the base station and information on a connection relationship between the terminal device and the mobile station. In addition, the base station confirms the destination terminal device of the data received from the transfer device, refers to the information stored in the storage unit, and the mobile station connected to the destination terminal device wirelessly communicates with the own station. In the case of a mobile station capable of communication, the mobile station includes a control unit that transmits received data to the communication area of the local station.

  The base station according to the present invention has an effect that a reduction in system throughput can be reduced while suppressing a loss of user data when the mobile station performs handover.

The figure which shows the structural example of the mobile communication system concerning Embodiment 1. FIG. FIG. 1 is a block diagram illustrating a configuration example of a transfer device according to a first embodiment; The figure which shows the example of the information of the connection relation of the user terminal and mobile station which the memory | storage part of the transfer apparatus concerning Embodiment 1 memorize | stores The figure which shows the example of the information of the relationship between the connection base station and the next connection base station which the memory | storage part of the transfer apparatus concerning Embodiment 1 memorize | stores. The figure which shows the example of the information of the relationship between the connection base station and mobile station which the memory | storage part of the transfer apparatus concerning Embodiment 1 memorize | stores FIG. 2 is a block diagram showing a configuration example of a base station according to the first embodiment. FIG. 3 is a sequence diagram showing operations of each device of the mobile communication system when user data is transmitted from the server according to the first embodiment to a user terminal. The figure which shows the example of the message format of the alerting | reporting information which the base station concerning Embodiment 1 transmits. The figure which shows the example of the message format of the location registration request | requirement which the mobile station concerning Embodiment 1 transmits, and the connection notification which a base station transmits. The figure which shows the example of the message format of the position registration response which the base station concerning Embodiment 1 transmits. The figure which shows the structural example of the user data which the server concerning Embodiment 1 transmits. 5 is a flowchart showing user data transmission processing of the transfer apparatus according to the first embodiment; 5 is a flowchart showing user data transmission processing of the transfer apparatus according to the first embodiment; The figure which shows the structural example of the processing circuit which implement | achieves the control part of the base station concerning Embodiment 1. FIG. The figure which shows the structural example of the user data which the server concerning Embodiment 2 transmits. FIG. 9 is a sequence diagram showing operations of respective devices of the mobile communication system when transmitting voice user data from the server according to the second embodiment to a user terminal. FIG. 9 is a flowchart showing user data transmission processing of the transfer apparatus according to the second embodiment; The figure which shows the example of the format of the IPv6 IP header provided to the user data which the server concerning Embodiment 3 transmits. The figure which shows the example of the detailed format of Traffic Class of the IPv6 IP header provided to the user data concerning Embodiment 3 10 is a flowchart showing user data transmission processing of the transfer apparatus according to the third embodiment;

  Hereinafter, a base station and a transfer apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a mobile communication system 1 according to the first embodiment of the present invention. Here, a train communication system is assumed in which mobile station 110 performs radio communication while handing over a plurality of base stations 103 to 105 on the ground side. The mobile station 110 is mounted on a train 109, which is a moving body that moves along a determined movement route.

  The mobile communication system 1 performs wireless communication on the ground side using a server 100, a transfer device 101, a network 102, a base station 103 that performs wireless communication using an LCX (Leaky CoaXial cable) 106, and an LCX 107. A base station 104 and a base station 105 that performs wireless communication using the LCX 108 are provided.

  The server 100 is installed in, for example, a command station and transmits / receives user data, which is data, to / from the user terminal 112 mounted on the train 109. The server 100 is connected to the transfer device 101 by an optical cable, for example. Here, as an example, a case where optical communication is performed between the server 100 and the transfer apparatus 101 is assumed, but wireless communication or the like may be used. The configuration of user data will be described later.

  The transfer apparatus 101 transfers the user data addressed to the user terminal 112 received from the server 100 to any one of the base stations 103 to 105 via the network 102, and receives the user data received from the base stations 103 to 105 via the network 102. Data is transferred to the server 100. A detailed configuration of the transfer apparatus 101 will be described later.

  The network 102 is a network used in communication between the transfer device 101 and the base stations 103 to 105 installed on the ground side. For example, an IP (Internet Protocol) network can be used as the network 102, but the network 102 is not limited to this.

  Base stations 103 to 105 are radio base stations used in the LCX communication system. In the mobile communication system 1 shown in FIG. 1, the LCX communication system is used for communication between the ground side and the train 109, but this is an example, and a millimeter wave communication system or the like may be used. The detailed configuration of the base stations 103 to 105 will be described later.

  A mobile train 109 in the mobile communication system 1 includes a mobile station 110, a transfer device 111, and a user terminal 112. The mobile station 110 connects to a user terminal 112 that is a terminal device via a transfer device 111.

  The mobile station 110 is a wireless mobile station used in the LCX communication system.

  The transfer device 111 transfers user data received from the user terminal 112 to the mobile station 110, and transfers user data received from the mobile station 110 to the user terminal 112.

  The user terminal 112 transmits / receives user data to / from the server 100 on the ground side.

  In the mobile communication system 1, for example, when transmitting user data from the server 100 to the user terminal 112, the server 100 includes the transfer device 101, the network 102, any of the base stations 103 to 105, the mobile station 110, and User data is transmitted to the user terminal 112 via the transfer device 111. When user data is transmitted from the user terminal 112 to the server 100, the flow is opposite to that described above. In the mobile communication system 1, between the base stations 103 to 105 and the mobile station 110 is a section for wireless communication by the LCX communication system.

  Next, the configuration of the transfer apparatus 101 will be described. FIG. 2 is a block diagram of a configuration example of the transfer apparatus 101 according to the first embodiment. The transfer apparatus 101 includes a control unit 11, a storage unit 12, an optical communication unit 13, and a network communication unit 14.

  The optical communication unit 13 has functions of a physical layer and a data link layer when performing optical communication in an OSI (Open Systems Interconnection) reference model. The optical communication unit 13 converts and demodulates user data received from the server 100 from an optical signal to an electrical signal, removes a MAC (Media Access Control) header and the like from the demodulated user data, and passes the user data to the control unit 11. . The optical communication unit 13 adds a MAC header or the like to the user data received from the control unit 11 to form a frame, modulates the user data, converts the electrical signal into an optical signal, and transmits the data to the server 100. The optical communication unit 13 includes, for example, an optical communication interface card and a driver circuit.

  The network communication unit 14 has functions of a physical layer and a data link layer when communication is performed on the network 102 such as an IP network in the OSI reference model. The network communication unit 14 demodulates user data transmitted from the train 109 and received via any of the base stations 103 to 105 and the network 102, removes a MAC header or the like from the demodulated user data, and controls the user data. Hand over to. The network communication unit 14 adds a MAC header or the like to the user data received from the control unit 11 to form a frame, modulates the user data, and transmits the user data to any of the base stations 103 to 105 via the network 102. The network communication unit 14 includes, for example, an interface card for communication via an IP network and a driver circuit.

  The control unit 11 has functions higher than the network layer in the OSI reference model. The control unit 11 passes the user data received from the network communication unit 14 to the optical communication unit 13. In addition, the control unit 11 passes the user data received from the optical communication unit 13 to the network communication unit 14. Specifically, the control unit 11 performs control to transmit user data from the user terminal 112 to the server 100, and transmits user data from the server 100 to the user terminal 112 via any of the base stations 103 to 105. Control. Further, the control unit 11 causes the storage unit 12 to store information on the base station to which the mobile station 110 is currently connected based on the connection notification received from any of the base stations 103 to 105. The control unit 11 refers to the information stored in the storage unit 12, determines a base station that transmits user data received from the server 100, and transmits the user data to the determined base station. The control unit 11 includes a processing circuit that executes functions higher than the network layer, for example, a UDP (User Datagram Protocol) / IP protocol by software. The contents of the connection notification message will be described later.

  The storage unit 12 stores information on which mobile station the user terminal is connected to. FIG. 3 is a diagram illustrating an example of connection relationship information between the user terminal and the mobile station stored in the storage unit 12 of the transfer apparatus 101 according to the first embodiment. In FIG. 3, as an example, the information 200 indicates that the user terminal 112 is connected to the mobile station 110. In the mobile communication system 1 shown in FIG. 1, the number of trains is one, but this is an example, and communication can be performed for a plurality of trains. The storage unit 12 stores in advance information shown in FIG. 3, that is, information on which mobile station the user terminal is connected to.

  In addition, the storage unit 12 stores information that can confirm a base station to be connected next by using the base station to which the mobile station 110 is currently connected as a search key. FIG. 4 is a diagram illustrating an example of information on a relationship between the connection base station and the next connection base station stored in the storage unit 12 of the transfer apparatus 101 according to the first embodiment. The connected base station indicates a base station to which the mobile station is currently connected, and the next connected base station indicates a base station to be connected next when the mobile station moves. This is information on the relationship between the base station with which the mobile station 110 is currently performing radio communication and the base station with which the mobile station 110 will next perform radio communication. In FIG. 4, as an example, in the information 300, when the mobile station 110 is currently connected to the base station 103, the mobile station 110 moves and the next base station to be connected is the base station 104. . In addition, the memory | storage part 12 shall memorize | store the information shown in FIG. 4 for every route and the advancing direction. For example, when the information shown in FIG. 4 is information on the uplink direction of a certain route, the storage unit 12 has the base station 104 as the connection base station and the base station 103 as the next connection base station in the downlink direction of the same route. I remember information. The storage unit 12 stores information shown in FIG. 4 in advance. 3 and 4 may be set in the transfer device 101 by the person in charge of the mobile communication system 1, or set in the server 100 by the person in charge of the mobile communication system 1, and the transfer device from the server 100 to the information shown in FIG. 101 may be distributed.

  In addition, the storage unit 12 stores information on the relationship between the connection base station 103 and the mobile station 110 based on the connection notification received by the control unit 11. FIG. 5 is a diagram of an example of information on the relationship between the connected base station and the mobile station stored in the storage unit 12 of the transfer apparatus 101 according to the first embodiment. In FIG. 5, as an example, the information 400 indicates that the mobile station 110 is connected to the base station 103, that is, the base station 103 can wirelessly communicate with the mobile station 110. The information shown in FIG. 5 is information that is updated each time the control unit 11 receives a connection notification from any of the base stations. The storage unit 12 is configured by a memory, for example.

  Next, the configuration of the base stations 103 to 105 will be described. Since the base stations 103 to 105 have the same configuration, the base station 103 will be described as an example here. FIG. 6 is a block diagram of a configuration example of the base station 103 according to the first embodiment. The base station 103 includes a control unit 31, a storage unit 32, an LCX communication unit 33, and a network communication unit 34.

  The LCX communication unit 33 has functions of a physical layer and a data link layer when performing LCX communication in the OSI reference model. The LCX communication unit 33 demodulates the user data from the mobile station 110 received by the LCX 106, removes the MAC header and the like from the demodulated user data, and passes the user data to the control unit 31. Further, the LCX communication unit 33 adds a MAC header or the like to the user data received from the control unit 31 to form a frame, modulates the user data, and transmits the user data from the LCX 106 to the mobile station 110. The LCX communication unit 33 includes, for example, an interface card for LCX communication and a driver circuit.

  The network communication unit 34 has functions of a physical layer and a data link layer when communication is performed on the network 102 such as an IP network in the OSI reference model. The network communication unit 34 demodulates user data transmitted from the server 100 and received via the transfer apparatus 101 and the network 102, removes a MAC header and the like from the demodulated user data, and passes the user data to the control unit 31. The network communication unit 34 adds a MAC header or the like to the user data received from the control unit 31 to form a frame, modulates the user data, and transmits the user data to the server 100 via the network 102 and the transfer device 101. The network communication unit 34 includes, for example, an interface card for communication via an IP network and a driver circuit.

  The control unit 31 has functions higher than the network layer in the OSI reference model. The control unit 31 transfers user data received from the network communication unit 34 to the LCX communication unit 33, and transfers user data received from the LCX communication unit 33 to the network communication unit 34. When receiving a location registration request from the mobile station 110, the control unit 31 performs control to transmit a connection notification to the transfer apparatus 101 after establishing a communication path and to transmit a location registration response to the mobile station 110. Based on the location registration request received from the mobile station 110, the control unit 31 causes the storage unit 32 to store information on the mobile station 110 that is connected to the local station, that is, capable of wireless communication with the local station. Specifically, when receiving the user data from the transfer apparatus 101, the control unit 31 confirms the user terminal 112 that is the destination of the received user data, and refers to information described later stored in the storage unit 32. When the mobile station 110 to which the destination user terminal 112 is connected is a mobile station capable of wireless communication with the own station, the control unit 31 transmits the received data to the communication area of the own station via the LCX communication unit 33 and the LCX 106. Send to. The control unit 31 is configured by a processing circuit that executes functions higher than the network layer, for example, UDP / IP protocol by software. The message content of the location registration request will be described later.

  The storage unit 32 stores information on the mobile station 110 that is connected to the own station based on the location registration request received by the control unit 31, that is, that can wirelessly communicate with the own station. Further, the storage unit 32 stores information similar to the information on the connection relationship between the user terminal and the mobile station shown in FIG. The information shown in FIG. 3 may be set by the person in charge of the mobile communication system 1 in the base station 103 or distributed from the transfer apparatus 101 to the base station 103. The storage unit 32 is configured by a memory, for example.

  In addition, about the server 100, the mobile station 110, the transfer apparatus 111, and the user terminal 112, since it is a common structure in a train communication system, description about a detailed structure is abbreviate | omitted.

  Subsequently, when user data is transmitted from the server 100 to the data terminal 112, an operation in which the base stations 103 to 105 that have received the user data from the server 100 via the transfer device 101 transmit the user data to the mobile station 110 will be described. To do. Here, specifically, the server 100 and the user terminal 112 communicate with each other in a state where the mobile station 110 exists in the communication area of the base station 103, and then the mobile station 110 moves and the communication area of the base station 104 moves. The operation of the base station 103 and the base station 104 when moving to FIG. FIG. 7 is a sequence diagram illustrating the operation of each device of the mobile communication system 1 when transmitting user data from the server 100 to the user terminal 112 according to the first embodiment. Here, it is assumed that the mobile station 110 starts up in the communication area of the base station 103 and starts operation.

  First, the control unit 31 of the base station 103 generates broadcast information for the communication area of the local station, and transmits the broadcast information to the communication area of the local station via the LCX communication unit 33 and the LCX 106 (step S101). Although omitted in FIG. 7, it is assumed that the base station 103 periodically transmits broadcast information.

  FIG. 8 is a diagram illustrating an example of a message format of broadcast information transmitted by the base station 103 according to the first embodiment. The broadcast information includes information of message type 500 and broadcast information base station ID (IDentification) 501. In the message type 500, a value indicating that the message type is broadcast information is set. In the broadcast information base station ID 501, an ID of a base station that transmits broadcast information, here, an ID indicating the base station 103 is set. The ID is information for identifying each device, and as an example, a code assigned to each device in FIG. 1 is used. The broadcast information may include base station operation information, which is omitted here.

  The mobile station 110 that has received the broadcast information in the communication area of the base station 103 knows that it can connect to the base station 103 from the value of the broadcast transmission base station ID 501 in the broadcast information. Thereby, the mobile station 110 transmits a location registration request for requesting registration of the location of the mobile station to the base station 103 (step S102).

  In the base station 103, the control unit 31 that has received the location registration request via the LCX 106 and the LCX communication unit 33 connects to the mobile station 110 connected to the local station included in the location registration request, that is, the mobile station 110 capable of wireless communication with the local station. Is stored in the storage unit 32. Then, the control unit 31 establishes a communication path between the mobile station 110 and the own station (step S103). After the communication path is established, the control unit 31 transmits a connection notification for notifying that the mobile station 110 is connected to the local station to the transfer apparatus 101 via the network communication unit 34 and the network 102 (step). S104).

  FIG. 9 is a diagram illustrating an example of a message format of a location registration request transmitted by the mobile station 110 and a connection notification transmitted by the base station 103 according to the first embodiment. The location registration request and the connection notification include information on the message type 600, the connected base station ID 601, and the connected mobile station ID 602. In the message type 600, a value indicating that the message type is a location registration request or a connection notification is set. The connected base station ID 601 is set with the ID of the base station to which the mobile station 110 is connected. Here, the ID indicating the base station 103 is set from the information of the broadcast transmission base station ID 501 included in the broadcast information. In the connected mobile station ID 602, an ID of a mobile station connected to the base station 103, here, an ID indicating the mobile station 110 is set. Information other than the information described above may be set in the location registration request and connection notification, but they are omitted here.

  In the transfer apparatus 101, the control unit 11 that has received the connection notification via the network 102 and the network communication unit 14 recognizes that the mobile station 110 is connected to the base station 103. The control unit 11 stores the information 400 of the connection base station 103 and the mobile station 110 in the storage unit 12 as information on the relationship between the connection base station and the mobile station shown in FIG.

  After transmitting the connection notification to the transfer apparatus 101, the control unit 31 of the base station 103 generates a location registration response indicating the location registration result for the location registration request, and moves the generated location registration response via the LCX communication unit 33 and the LCX 106. It transmits to the station 110 (step S105).

  FIG. 10 is a diagram illustrating an example of a message format of a location registration response transmitted by the base station 103 according to the first embodiment. The location registration response includes information of message type 700, location registration result 701, connected base station ID 702, and connected mobile station ID 703. In the message type 700, a value indicating that the message type is a location registration response is set. In the position registration result 701, a value indicating that the position registration has been accepted is set here. In the connected base station ID 702, the ID of the base station that has accepted the location registration, here, the ID indicating the base station 103 is set. In the connected mobile station ID 703, an ID of the mobile station that transmitted the location registration request, here, an ID indicating the mobile station 110 is set. Information other than the above information may be set in the location registration response, but it is omitted here.

  Accordingly, the mobile station 110 that has received the location registration response knows that the location registration has been successful.

  The server 100 adds a header including destination information whose destination is the user terminal 112 to the user data, and transmits the user data to the transfer apparatus 101 (step S106). FIG. 11 is a diagram illustrating a configuration example of user data transmitted by the server 100 according to the first embodiment. User data transmitted by the server 100 includes an IP header 800, a UDP header 801, and application data 802. A UDP header 801 is added to the application data 802 of the data portion used by the user terminal 112, and an IP header 800 is further added. This is a format generally used in UDP / IP, and the IP header 800 includes user data destination information. Although FIG. 11 shows a general UDP / IP format, this is merely an example, and the server 100 may transmit user data in the TCP (Transmission Control Protocol) / IP format.

  When the control unit 11 of the transfer apparatus 101 receives user data from the server 100 via the optical communication unit 13, the control unit 11 confirms that the destination is addressed to the user terminal 112 from the destination information of the header given to the user data. Next, from the information 200 shown in FIG. 3 stored in the storage unit 12, the control unit 11 confirms that the user terminal 112 is connected to the mobile station 110. Further, the control unit 11 confirms from the information 400 shown in FIG. 5 stored in the storage unit 12 that the mobile station 110 is currently connected to the base station 103. Further, the control unit 11 confirms from the information 300 shown in FIG. 4 stored in the storage unit 12 that the mobile station 110 is connected to the base station 104 next to the base station 103. Therefore, the control unit 11 includes a base station 103 that is currently performing wireless communication with the mobile station 110 to which the user terminal 112 is connected, and a base station 104 that is next to perform wireless communication with the mobile station 110. Decide to send to.

  The control unit 11 of the transfer apparatus 101 transmits the user data received from the server 100 to the base station 103 to which the mobile station 110 is currently connected via the network communication unit 14 and the network 102 (step S107). Further, the control unit 11 of the transfer apparatus 101 duplicates the user data received from the server 100 and connects the duplicated user data to the next when the mobile station 110 moves via the network communication unit 14 and the network 102. It transmits to the base station 104 (step S108). Thus, the transfer apparatus 101 transmits user data to the base stations 103 and 104 by bicast. In addition, when transmitting the user data to the base stations 103 and 104, the control unit 11 of the transfer apparatus 101 may transmit the user data to the base stations 103 and 104 using an IP tunnel.

  The operation of the transfer apparatus 101 will be described using a flowchart. FIG. 12 is a flowchart of user data transmission processing of the transfer apparatus 101 according to the first embodiment. When receiving the user data from the server 100 via the optical communication unit 13 (step S1), the control unit 11 of the transfer apparatus 101 confirms the destination user terminal of the received user data (step S2). Next, the control unit 11 refers to the storage unit 12, confirms the mobile station to which the user terminal is connected (step S3), and confirms the base station to which the mobile station is currently connected (step S4). The mobile station confirms the next base station to be connected (step S5). Then, the control unit 11 transmits user data to the base station to which the mobile station is currently connected (step S6), and transmits user data to the base station to which the mobile station is next connected (step S7). As described above, the control unit 11 of the transfer apparatus 101 determines that the mobile station 110 that is currently performing wireless communication with the mobile station 110 to which the user terminal 112 that is the destination of user data is connected, and the mobile station 110 perform wireless communication next. It decides to transmit user data to the base station 104 that will perform the operation, and transmits the user data to the base stations 103 and 104.

  Returning to the description of the sequence diagram of FIG. When receiving the user data from the transfer apparatus 101 via the network 102 and the network communication unit 34, the control unit 31 of the base station 103 confirms the destination of the user data with the user terminal 112 from the destination information of the header given to the user data. . The control unit 31 of the base station 103 checks whether or not the mobile station 110 connected to the user terminal 112 that is the destination of user data is a mobile station connected to the own station. Here, the control unit 31 of the base station 103 refers to the connection relationship between the user terminal and the mobile station shown in FIG. 3 stored in the storage unit 32, and the user terminal 112 is connected to the mobile station 110. Make sure. In addition, the control unit 31 of the base station 103 stores information indicating that the mobile station 110 is connected to the own station in the storage unit 32 in the processes of steps S101 to S102. When the control unit 31 of the base station 103 confirms that the mobile station 110 connected to the user terminal 112 that is the destination of user data is the mobile station 110 connected to its own station, the control unit 31 transmits the user data to the LCX communication unit 33 and It transmits to its own communication area, that is, the mobile station 110 via the LCX 106 (step S109).

  When receiving the user data from the transfer apparatus 101 via the network 102 and the network communication unit 34, the control unit 31 of the base station 104 confirms the destination with the user terminal 112 from the destination information of the header given to the user data. The control unit 31 of the base station 104 checks whether or not the mobile station 110 connected to the user terminal 112 that is the destination of user data is a mobile station connected to the own station. Here, the control unit 31 of the base station 104 refers to the connection relationship between the user terminal and the mobile station shown in FIG. 3 stored in the storage unit 32, and the user terminal 112 is connected to the mobile station 110. Make sure. Further, the control unit 31 of the base station 104 does not store the information that the mobile station is connected to the own station in the storage unit 32. When the control unit 31 of the base station 104 confirms that the mobile station 110 connected to the user terminal 112 of the user data destination is not connected to the own station, the control unit 31 discards the user data without transmitting it (step S110). .

  The mobile station 110 that has received the user data from the base station 103 transmits the received user data to the user terminal 112 via the transfer device 111 (step S111).

  Thereafter, the mobile station 110 moves in the direction of the base station 104 (step S112).

  The control unit 31 of the base station 104 generates broadcast information for the communication area of the local station, and transmits the broadcast information to the communication area of the local station via the LCX communication unit 33 and the LCX 107 (step S113). The message format of the broadcast information is the same as in FIG. 8 described above, but the broadcast transmission base station ID 501 is set with the ID of the base station that transmits the broadcast information, here the ID indicating the base station 104. Although omitted in FIG. 7, it is assumed that the base station 104 periodically transmits the broadcast information, like the base station 103.

  The mobile station 110 that has entered the communication area of the base station 104 and has received the broadcast information knows that it can connect to the base station 104 from the value of the broadcast transmission base station ID 501 in the broadcast information. Thereby, the mobile station 110 transmits a location registration request for requesting registration of the location of the mobile station to the base station 104 (step S114). The message format of the location registration request is the same as that in FIG. 9 described above, but the base station ID is determined from the ID of the base station connected to the connected base station ID 601 by the mobile station 110, here the information of the notification transmission base station ID 501 included in the notification information An ID indicating 104 is set.

  In the base station 104, the control unit 31 that has received the location registration request via the LCX 107 and the LCX communication unit 33 connects the mobile station 110 connected to the local station included in the location registration request, that is, a mobile station capable of wireless communication with the local station. 110 information is stored in the storage unit 32. At this time, the control unit 31 transmits the connection notification to the transfer apparatus 101 and the mobile station 110 because the mobile station 110 is still communicating with the base station 103 and the handover to the own station is not executed. No location registration response is sent to

  The server 100 adds a header including destination information whose destination is the user terminal 112 to the user data, and transmits the user data to the transfer apparatus 101, similarly to the processing in step S106 described above (step S115).

  The control unit 11 of the transfer apparatus 101 transmits the user data received from the server 100 to the base stations 103 and 104 by bicast, similarly to the processes of steps S107 and S108 described above (steps S116 and S117).

  The control unit 31 of the base station 103 transmits the user data received from the transfer apparatus 101 to the communication area of the own station, that is, the mobile station 110, similarly to the process of step S109 described above (step S118).

  When receiving the user data from the transfer apparatus 101 via the network 102 and the network communication unit 34, the control unit 31 of the base station 104 confirms the destination of the user data with the user terminal 112 from the destination information of the header given to the user data. . The control unit 31 of the base station 104 checks whether or not the mobile station 110 connected to the user terminal 112 that is the destination of user data is a mobile station connected to the own station. Here, the control unit 31 of the base station 104 refers to the connection relationship between the user terminal and the mobile station shown in FIG. 3 stored in the storage unit 32, and the user terminal 112 is connected to the mobile station 110. Make sure. In addition, the control unit 31 of the base station 104 stores information indicating that the mobile station 110 is connected to the own station in the storage unit 32 in the processes of steps S113 to S114. When the control unit 31 of the base station 104 confirms that the mobile station 110 connected to the user terminal 112 that is the destination of user data is the mobile station 110 connected to its own station, the control unit 31 transmits the user data to the LCX communication unit 33 and The data is transmitted to the communication area of the own station, that is, the mobile station 110 via the LCX 107 (step S119).

  The mobile station 110 that has received the user data from the base stations 103 and 104 transmits any of the received user data to the user terminal 112 via the transfer device 111 (step S120).

  Thereafter, when the mobile station 110 further moves in the direction of the base station 104 and cannot receive the broadcast information from the base station 103 (step S121), the mobile station 110 switches the base station for communication from the base station 103 to the base station 104. Is executed (step S122). Note that the timing for executing the handover is not limited to the case where the mobile station 110 can no longer receive the broadcast information from the base station 103. For example, the mobile station 110 may measure the reception quality of the broadcast information from the base station 103, and may perform a handover when the reception quality falls below a prescribed reception quality threshold.

  When the control unit 31 of the base station 104 establishes a communication path between the mobile station 110 and itself by handover of the mobile station 110, the control unit 31 transmits the mobile station to the transfer apparatus 101 via the network communication unit 34 and the network 102. A connection notification for notifying that 110 is connected to the local station is transmitted (step S123). The message format of the connection notification is the same as that in FIG. 9 described above, but the base station ID 601 is the base station ID to which the mobile station 110 is connected. An ID indicating 104 is set.

  In the transfer apparatus 101, the control unit 11 that has received the connection notification via the network 102 and the network communication unit 14 recognizes that the mobile station 110 has connected to the base station 104. The control unit 11 updates the information of the connection base station 103 and the mobile station 110 to the information of the connection base station 104 and the mobile station 110 as information on the relationship between the connection base station and the mobile station shown in FIG. 12 is stored.

  After transmitting the connection notification to the transfer apparatus 101, the control unit 31 of the base station 104 generates a location registration response indicating the location registration result for the location registration request, and moves the generated location registration response via the LCX communication unit 33 and the LCX 106. Transmit to the station 110 (step S124). The message format of the location registration response is the same as in FIG. 10 described above, but the ID of the base station that accepted the location registration, here the ID indicating the base station 104, is set in the connected base station ID 702.

  The control unit 31 of the base station 103 deletes, from the storage unit 32, information on the mobile station 110 that is connected to the own station, that is, that can communicate with the own station after the handover. For a method of grasping that the mobile station 110 has executed a handover in the control unit 31 of the base station 103, for example, a notification may be received from the base station 104 via the network 102, and handover between each base station is managed. The notification may be received from a device such as a handover management device (not shown), but is not limited thereto.

  The mobile station 110 may receive both user data from the base station 103 and user data from the base station 104 by means such as MIMO (Multiple Input and Multiple Output).

  In FIG. 7, the transfer apparatus 101 performs bicast transmission of user data. However, for example, a router is installed in the network 102, and the router has the function of the transfer apparatus 101 to transmit user data by bicast. You may go.

  The operation of the base stations 103 and 104 shown in the sequence diagram of FIG. 7 will be described using a flowchart. FIG. 13 is a flowchart of user data transmission processing of the transfer apparatus 101 according to the first embodiment. When receiving the user data from the transfer apparatus 101 (step S11), the control unit 31 of the base stations 103 and 104 confirms the destination of the user data from the destination information of the header given to the user data (step S12). When the mobile station connected to the user terminal that is the destination of user data is a mobile station connected to the own station (step S13: Yes), the control unit 31 transmits the user data via the LCX communication unit 33 and the LCX 106. Transmit to the communication area of the station (step S14). When the mobile station connected to the user terminal that is the destination of user data is not connected to the own station (step S13: No), the control unit 31 discards the user data (step S15).

  Next, the hardware configuration of the base stations 103 to 105 will be described. As described above, the LCX communication unit 33 includes an interface card for LCX communication and a driver circuit. The network communication unit 34 includes an interface card for communication via a network such as an IP network and a driver circuit. The storage unit 32 is configured by a memory. FIG. 14 is a diagram illustrating a configuration example of a processing circuit 90 that implements the control unit 31 of the base stations 103 to 105 according to the first embodiment. The processing circuit 90 includes a processor 91 that executes a program stored in the memory 92, a memory 92 that stores information such as a program executed by the processor 91, and an input interface circuit 93 to which data and the like are input from other configurations. An output interface circuit 94 for outputting data and the like to other components is provided, and a processor 91, a memory 92, an input interface circuit 93, and an output interface circuit 94 are connected by a system bus 95.

  The functions of the control unit 31 of the base stations 103 to 105 are realized by the processing circuit 90. That is, the base stations 103 to 105 confirm the destination of the received user data, and transmit user data if the mobile station connected to the user terminal of the user data is a mobile station connected to the own station. When the mobile station connected to the user terminal that is the destination of the user data is not connected to the own station, the mobile station includes a processing circuit 90 for discarding the user data. In the processing circuit 90, it is not the processor 91 that executes the program stored in the memory 92, but a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal). Processor) or the like.

  The function of the control unit 31 is realized by software, firmware, or a combination of software and firmware. Software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, the processor 91 reads out and executes the program stored in the memory 92, thereby realizing the function of the control unit 31. That is, when the base station 103-105 is executed by the processing circuit 90, the base station 103 confirms the destination of the received user data, and the mobile station connected to the user terminal of the user data destination connects to its own station. As a result, a step of transmitting user data is performed in the case of a mobile station, and a step of discarding user data is performed if the mobile station connected to the user terminal of the user data is not connected to the own station. A memory 92 is provided for storing the program to be stored. Moreover, it can be said that these programs are what makes a computer perform the procedure and method of the control part 31. FIG. Here, the memory 92 is a non-volatile or volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), etc. A semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disc), or the like is applicable.

  Although the configuration of the control unit 31 of the base stations 103 to 105 has been described, the control unit 11 of the transfer apparatus 101 is also realized by the processing circuit 90 illustrated in FIG.

  As described above, according to the present embodiment, the base station uses the location registration information of the mobile station to determine whether or not user data can be transmitted to its own communication area. When the base station receives user data from the transfer device, if the mobile station connected to the user terminal that is the destination of the user data is a mobile station that exists in its own communication area and can perform wireless communication, the base station Send to your station's communication area. When the base station receives user data from the transfer device, if the mobile station connected to the user terminal that is the destination of user data is a mobile station that does not exist in its own communication area and cannot be wirelessly communicated, the base station Discard without sending. Thus, even if the base station receives user data from the transfer device, the base station does not transmit user data when there is no mobile station connected to the user terminal that is the destination of user data in the communication area of the base station. Thereby, in the base station, before the mobile station moves to the communication area of the own station, an effect of reducing the compression of the radio band can be obtained.

  In addition, since the transfer device transmits user data to the destination base station to which the mobile station connects next, if the location registration procedure from the mobile station has been performed up to the destination base station, The previous base station can transmit user data to the mobile station. As a result, the base station can reduce the loss of user data with respect to the moving mobile station.

Embodiment 2. FIG.
In the first embodiment, the base station determines whether or not user data can be transmitted based on the connection information of the mobile station. In the second embodiment, the base station determines whether or not transmission is possible depending on whether or not the user data is voice. The configuration of the mobile communication system 1 and each device is the same as that of the first embodiment.

  In the second embodiment, the control unit 31 of the base stations 103 to 105 determines whether the received user data is voice user data or user data other than voice depending on the presence or absence of an RTP (Real time Transport Protocol) header. . FIG. 15 is a diagram illustrating a configuration example of user data transmitted by the server 100 according to the second embodiment. User data transmitted by the server 100 includes an IP header 800, a UDP header 801, an RTP header 803, and application data 802. The RTP header 803 is added to the user data shown in FIG. The control unit 31 of the base stations 103 to 105 determines that the IP data including the RTP header in the received user data is voice user data. The IP version may be IPv4 (Internet Protocol version 4) or IPv6.

  FIG. 16 is a sequence diagram illustrating the operation of each device of the mobile communication system 1 when transmitting audio user data from the server 100 to the user terminal 112 according to the second embodiment. The processing from step S201 to S205 is the same as the processing from step S101 to S105 in the sequence diagram shown in FIG. 7 of the first embodiment.

  The server 100 adds a header including destination information whose destination is the user terminal 112 to the user data, and transmits the user data to the transfer apparatus 101 (step S206). Here, since the server 100 has transmitted audio user data, it is assumed that an RTP header is added to the user data.

  The control unit 11 of the transfer apparatus 101 transmits the user data received from the server 100 to the base stations 103 and 104 by bicast, similarly to the processing of steps S107 and S108 in the sequence diagram shown in FIG. 7 of the first embodiment ( Steps S207 and S208).

  The control unit 31 of the base station 103 transmits the user data received from the transfer apparatus 101 to the mobile station 110 as in the process of step S109 in the sequence diagram shown in FIG. 7 of the first embodiment (step S209).

  When receiving the user data from the transfer apparatus 101 via the network 102 and the network communication unit 34, the control unit 31 of the base station 104 confirms the destination with the user terminal 112 from the destination information of the header given to the user data. The control unit 31 of the base station 104 checks whether or not the mobile station 110 connected to the user terminal 112 that is the destination of user data is a mobile station connected to the own station. Here, the control unit 31 of the base station 104 does not store information indicating that the mobile station is connected to the own station in the storage unit 32. If the control unit 31 of the base station 104 confirms that the mobile station 110 connected to the user terminal 112 to which the user data is destined is not connected to its own station, then whether the received user data is voice user data or not. Confirm whether or not.

  Since the RTP header is added to the received user data, the control unit 31 of the base station 104 determines that the received user data is voice user data. When the control unit 31 of the base station 104 determines that the received user data is voice user data, the user data is transmitted to the communication area of the own station, that is, the mobile station 110 via the LCX communication unit 33 and the LCX 107 ( Step S210). If the control unit 31 of the base station 104 determines that the received user data is not voice user data, that is, if the RTP header is not added to the received user data, the user data is not transmitted. Discard. In this way, the control unit 31 of the base station 104 confirms the type of received user data when the mobile station 110 connected to the user terminal 112 to which user data is destined is a mobile station that cannot wirelessly communicate with its own station. However, when the received data is a specified type of data, ie, voice user data in the above example, the received user data is transmitted to the communication area of the own station.

  The mobile station 110 that has received the user data from the base stations 103 and 104 transmits any of the received user data to the user terminal 112 via the transfer device 111 (step S211).

  The operation of the base stations 103 and 104 shown in the sequence diagram of FIG. 16 will be described using a flowchart. FIG. 17 is a flowchart of user data transmission processing of the transfer apparatus 101 according to the second embodiment. The part different from the flowchart of FIG. 13 shown in the first embodiment is that the control unit 31 is not connected to the mobile station connected to the user terminal that is the destination of user data (step S13: No). Further, it is confirmed whether or not the received user data is voice user data (step S21). When the received user data is voice user data (step S21: Yes), the control unit 31 transmits the user data to the communication area of the own station via the LCX communication unit 33 and the LCX 106 (step S14). When the received user data is not voice user data (step S21: No), the control unit 31 discards the user data (step S15).

  As described above, according to the present embodiment, the base station does not transmit all user data even when there is no mobile station connected to the user terminal that is the destination of user data in its communication area. Rather, it is determined whether or not the user data is voice user data based on the presence or absence of the RTP header, and voice user data that is severely demanded for delay and loss is transmitted to the communication area of the local station. Thereby, in the base station, it is possible to reduce the loss of voice user data that is severely demanded for delay and loss for the moving mobile station.

Embodiment 3 FIG.
In the second embodiment, when the base station receives voice user data, the base station transmits user data even if the mobile station is not connected. In the third embodiment, whether or not user data can be transmitted is further determined based on information in the IP header. The configuration of the mobile communication system 1 and each device is the same as that of the first embodiment.

  In Embodiment 3, the control unit 31 of the base stations 103 to 105 determines whether or not user data can be transmitted based on, for example, the traffic class information of the IP header 800 of the received user data. FIG. 18 is a diagram illustrating an example of a format of an IPv6 IP header 800 attached to user data transmitted by the server 100 according to the third embodiment. The IPv6 IP header 800 is composed of Version 900, Traffic Class 901, Flow Label 902, Payload Length 903, Next Header 904, Hop Limit 905, Source Address 906, and Destination Address 907. FIG. 19 is a diagram illustrating an example of a detailed format of the Traffic Class 901 of the IPv6 IP header 800 attached to the user data according to the third embodiment. The Traffic Class 901 includes a DSCP (Differentiated Services Code Point) 908 and an ECN (Explicit Congestion Notification) 909.

  The server 100 sets, for example, a value of 46 in decimal number in the DSCP 908 of the Traffic Class 901 in the IP header 800 for the voice user data to be given the highest priority among the voice user data to be transmitted.

  The operation of each device in the third embodiment is the same as the sequence diagram of FIG. 16 shown in the second embodiment. The difference between the second embodiment and the third embodiment is only the process of step S210.

  When receiving the user data from the transfer apparatus 101 via the network 102 and the network communication unit 34, the control unit 31 of the base station 104 confirms the destination with the user terminal 112 from the destination information of the header given to the user data. The control unit 31 of the base station 104 checks whether or not the mobile station 110 connected to the user terminal 112 that is the destination of user data is a mobile station connected to the own station. Here, the control unit 31 of the base station 104 does not store information indicating that the mobile station is connected to the own station in the storage unit 32. If the control unit 31 of the base station 104 confirms that the mobile station 110 connected to the user terminal 112 to which the user data is destined is not connected to its own station, then whether the received user data is voice user data or not. Confirm whether or not.

  Since the RTP header is added to the received user data, the control unit 31 of the base station 104 determines that the received user data is voice user data. When determining that the received user data is voice user data, the control unit 31 of the base station 104 next checks the DSCP 908 of the Traffic Class 901 in the IP header 800 of the user data.

  When the value of DSCP 908 of Traffic Class 901 in the IP header 800 of the user data is 46, the control unit 31 of the base station 104 uses the user data of the received voice as the user data of the voice to be given the highest priority, and performs the LCX communication. It transmits to the mobile station 110 via the unit 33 and the LCX 107 (step S210). Note that if the value of DSCP 908 of Traffic Class 901 in the IP header 800 of the user data is a value other than 46, the control unit 31 of the base station 104 discards the user data without transmitting it. In this way, the control unit 31 of the base station 104 confirms the type of received user data when the mobile station 110 connected to the user terminal 112 to which user data is destined is a mobile station that cannot wirelessly communicate with its own station. When the received data is data of a specified type, in the above example, voice user data, the header of the received data is further confirmed. The control unit 31 of the base station 104 receives the received data in the area specified in the header, in the above example, the value of the DSCP 908 of the Traffic Class 901 in the IP header 800 is specified, and in the above example, 46. Send to your station's communication area.

  In the third embodiment, the control unit 31 of the base stations 103 to 105 determines whether or not user data can be transmitted based on the value of the DSCP 908. However, this is only an example, and other parameters in the IP header 800, the UDP header 801 Or the parameters in the RTP header 803 or the like. That is, the control unit 31 of the base stations 103 to 105 determines whether or not user data can be transmitted depending on whether or not a value of a certain area in the header given to the user data is a specified value.

  The operation of base stations 103 and 104 in Embodiment 3 will be described using a flowchart. FIG. 20 is a flowchart of user data transmission processing of the transfer apparatus 101 according to the third embodiment. The part different from the flowchart of FIG. 17 shown in the second embodiment is that the control unit 31 has a header in the user data when the received user data is voice user data (step S21: Yes). It is confirmed whether or not the value of the area is a prescribed value (step S31). When the parameter in the header given to the user data, that is, the value of a certain area is a specified value (step S31: Yes), the control unit 31 transmits the user data to the local station via the LCX communication unit 33 and the LCX 106. Transmit to the area (step S14). If the parameter in the header given to the user data, that is, the value of a certain area is not a prescribed value (step S31: No), the control unit 31 discards the user data (step S15).

  As described above, according to the present embodiment, when receiving the voice user data, the base station further confirms the header of the user data, and based on the DSCP value in the IP header, It was decided to determine whether transmission was possible. As a result, the base station can reduce the loss of voice user data only for a specific voice service with respect to the moving mobile station.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Mobile communication system, 11, 31 Control part, 12, 32 Storage part, 13 Optical communication part, 14, 34 Network communication part, 33 LCX communication part, 100 Server, 101, 111 Transfer apparatus, 102 Network, 103, 104, 105 base station, 106, 107, 108 LCX, 109 train, 110 mobile station, 112 user terminal.

Claims (3)

The base station in a mobile communication system comprising: a mobile station connected to a terminal device; a plurality of base stations that perform radio communication with the mobile station; and a transfer device that transmits data addressed to the terminal device to the base station. And
A storage unit for storing information on a mobile station capable of wireless communication with the own station, and information on a connection relationship between the terminal device and the mobile station;
Confirm the destination terminal device of the data received from the transfer device, refer to the information stored in the storage unit, and the mobile station connected to the destination terminal device can wirelessly communicate with its own station In the case of a mobile station, a control unit that transmits the received data to the communication area of the own station;
A base station comprising: The control unit confirms the type of the received data when the mobile station to which the destination terminal device is connected is a mobile station incapable of wireless communication with the own station, and the received data is of a specified type. When it is data, it transmits the received data to its own communication area.
The base station according to claim 1. When the mobile station to which the destination terminal device is connected is a mobile station incapable of wireless communication with the own station, the control unit checks the type of the received data, and the received data is of a specified type. For data, further check the header of the received data, and when the value of the area specified in the header is a specified value, transmit the received data to the communication area of its own station,
The base station according to claim 1.

Images