Communication system

Abstract

A communication system according to one embodiment of the invention is provided with a plurality of parent station devices and a plurality of child station devices, the parent station devices and the child station devices communicating one-to-one, wherein each of the parent station devices comprises: a connection status sharing unit for sharing with one another connection status information indicating whether the plurality of parent station devices are respectively connected to one of the child station devices; and a connection processing unit for performing processing by which any one child station device that has newly requested connection to any one parent station device is connected to a parent station device that is not connected to any of the child station devices, on the basis of the connection status information shared by the connection status sharing unit.

Description

communication systems

[0001] The present invention relates to communication systems.

[0002] An example of a communication system having multiple master station devices and multiple slave station devices is a satellite communication system that performs wireless communication via a relay station such as a satellite. For example, in a satellite communication system in which more signal processing devices (radio stations (portable stations)) than the number of simultaneous connections is deployed, the portable stations are managed by schedule reservation information installed in a control station, and operation reservations are made by an operator via an HMI (Human Machine Interface) connected to the control station (see, for example, Non-Patent Document 1).

[0003] As described above, in conventional satellite communication systems, in order for a master station device, which is a signal processing device, and a slave station device to establish a line connection via a satellite, schedule management from a control station, etc. Also, in order to establish a line connection between signal processing devices (for example, wireless stations (portable stations), etc.) without going through a control station or a control station, one of the signal processing devices must act as a master station and transmit a control signal.

[0004] In other words, the line connection between the portable stations is a connection between a master station and a slave station. In this case, the line connection between the wireless stations (portable stations) is such that the master station first starts up and transmits a control signal, the slave station synchronizes with the master station, and after the master station knows via the control line that the slave station is ready, communication signals are transmitted from both sides, and communication begins. Conventionally, the master station and the slave station have been connected in a fixed one-to-one relationship (see, for example, Non-Patent Document 2).

[0005] Akira Matsushita and seven others, "Infrastructure Satellite Communication System Applied to Disaster Countermeasure Services," NTT Technical Journal, September 2005. Hiroki Shibayama and three others, "A Study on a Satellite Communication System for Ensuring Communication Between Important Bases," IEICE General Conference, B-3-2, March 2020.

[0006] However, in the past, even if multiple sets of master station devices and slave station devices were provided, the master station devices and slave station devices were associated as pairs, and even if a slave station device requested a line connection, the slave station device could not start data communication unless the associated master station device was ready.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a communication system that can efficiently connect a plurality of master station devices and a plurality of slave station devices simultaneously.

[0008] A communication system according to one embodiment of the present invention is a communication system comprising a plurality of parent station devices and a plurality of child station devices, in which the parent station devices and the child station devices communicate one-to-one, characterized in that each of the parent station devices has a connection status sharing unit that shares connection status information with each other indicating whether each of the parent station devices is connected to any of the child station devices, and a connection processing unit that performs processing to connect one of the child station devices that has newly requested connection to any of the parent station devices to a parent station device that is not connected to any of the child station devices, based on the connection status information shared by the connection status sharing unit.

[0009] According to the present invention, a plurality of master station devices and a plurality of slave station devices can be efficiently connected simultaneously.

[0010] 1 is a diagram illustrating an overview of a communication system; FIG. 2 is a diagram illustrating the frequencies of signals managed by master station devices A and B; FIG. 3 is a timing chart illustrating the operation of master station device A; (a) is a diagram illustrating a state in which master station device A is transmitting a CSCO; (b) is a diagram illustrating a state in which slave station device a is transmitting a CSCI in response to the CSCO; (c) is a diagram illustrating the process when master station device A and slave station device a start communication; FIG. 4 is a timing chart illustrating the operation of a communication system including multiple master station devices and multiple slave station devices; (a) is a diagram illustrating a connection result of the communication system; (b) is a diagram illustrating a connection that cannot be realized in the communication system; FIG. 5 is a functional block diagram illustrating functions possessed by a master station device included in a communication system according to an embodiment; and FIG. 6 is a flowchart illustrating an example of the operation of a communication system according to an embodiment in which multiple master station devices and multiple slave station devices communicate via a satellite. 1A is a diagram schematically illustrating a state when a slave station device a transmits a connection request to a connected master station device A; FIG. 1B is a diagram schematically illustrating a state when a slave station device a transmits a CSCI in response to a CSCO of a master station device C; FIG. 1C is a diagram schematically illustrating a process when a master station device C and a slave station device a start communication; FIG. 1C is a timing chart illustrating a first operation example (available master station device management function) of a communication system according to an embodiment, which includes multiple master station devices and multiple slave station devices; FIG. 1A is a diagram schematically illustrating a state when a slave station device a transmits a connection request to a connected master station device A; FIG. 1B is a diagram schematically illustrating a state when a master station device A grasps the data communication status of other master station devices by CSCO; and FIG. 1C is a diagram schematically illustrating a state when a master station device A transmits an instruction to a master station device C to disconnect the connection. 1A is a diagram showing a state in which a master station device C has disconnected from a slave station device d after a predetermined connection time limit has elapsed, FIG. 1B is a diagram showing a state in which a slave station device a is transmitting a connection request to a master station device C using a CSCI, and FIG. 1C is a diagram showing a state in which a master station device C and a slave station device a have started communication.1 is a timing chart showing a second operation example (data communication management function) and a third operation example (a time limit management function and a line forced disconnection function accompanied by the data communication management function) of a communication system according to an embodiment, the communication system including a plurality of master station devices and a plurality of slave station devices; FIG. 2 is a diagram showing an example of a hardware configuration of a master station device according to an embodiment; and FIG. 3 is a diagram showing an overview of another example of a configuration of a communication system according to an embodiment.

[0011] The communication system will be described below with reference to the drawings. Fig. 1 is a diagram illustrating an example of an overview of a communication system 1. The communication system 1 is a satellite communication system that includes, for example, a plurality of master station devices and a plurality of slave station devices, and in which the master station devices and the slave station devices communicate one-to-one.

[0012] For example, communication system 1 includes master station devices A and B and slave station devices a and b, where master station device A performs wireless communication with slave station device a via satellite 2, and master station device B performs wireless communication with slave station device b via satellite 2.

[0013] The multiple master station devices may be individually located at different locations, or may be located at the same base or in the same housing. The multiple slave station devices may also be transceivers or mobile terminals capable of communicating with the satellite 2.

[0014] In this case, the communication system 1 secures a control line (CSC (Common Signaling Channel) line) dedicated to control signals, separate from communication lines for transmitting communication signals such as voice and data. Furthermore, a control signal transmitted from master station equipment A (or master station equipment B) to slave station equipment a (or slave station equipment b) is called a CSCO (Common Signaling Channel Outbound) signal, and a control signal transmitted from slave station equipment a (or slave station equipment b) to master station equipment A (or master station equipment B) is called a CSCI (Common Signaling Channel Inbound) signal. The CSCI signal is mainly a response to the CSCO signal and is a burst signal.

[0015] Before describing the configuration and operation of a communication system according to an embodiment, a master station device and a slave station device of a comparative example will be described first.

[0016] 2 is a diagram (comparison example) illustrating a schematic example of the frequencies of signals managed by master station devices A and B. Master station device A manages the communication signals of master station device A and slave station device a, as well as the CSCO signal of master station device A and the CSCI signal of slave station device a. Master station device B manages the communication signals of master station device B and slave station device b, as well as the CSCO signal of master station device B and the CSCI signal of slave station device b.

[0017] 3 is a timing chart (comparative example) illustrating the operation of master station equipment A. It is assumed that master station equipment A and slave station equipment a have already captured satellite 2.

[0018] For example, master station device A constantly transmits CSCO[A] from a master modem (not shown) (S10). Slave station device a receives CSCO[A], synchronizes, and transmits CSCI[a] from a slave modem (not shown) to master station device A to notify that synchronization has been completed (S11).

[0019] When master station device A receives CSCI[a] and confirms that slave station device a has synchronized and is ready for communication, it instructs the slave modem to transmit a communication signal via CSCO[A] (S12), and instructs the master modem to transmit a communication signal via CSCO[A] (S13: satellite return).

[0020] Then, the parent station device A transmits a communication signal [A] from its parent modem (S14), and the child station device a transmits a communication signal [a] from its child modem (S15), thereby putting the line from the parent station device A to the child station device a into communication.

[0021] 4A and 4B are diagrams (comparative example) showing a communication process when a communication system including multiple master station devices and multiple slave station devices performs the operation shown in FIG. 3. Fig. 4A is a diagram showing a state in which master station device A is transmitting a CSCO. Fig. 4B is a diagram showing a state in which slave station device a is transmitting a CSCI in response to the CSCO. Fig. 4C is a diagram showing a process when master station device A and slave station device a start communication.

[0022] In FIG. 4A, when slave station device a completes capturing satellite 2 and master station device A completes preparations for communication and transmits CSCO, slave station device a checks whether it can receive CSCO.

[0023] In FIG. 4B, the slave station equipment a synchronizes with the master station equipment A and transmits a line connection request to the master station equipment A using the CSCI.

[0024] 4(c), master station equipment A receives a connection request from slave station equipment a, permits connection to slave station equipment a, and instructs it to transmit a communication signal. When slave station equipment a transmits a communication signal in response to the connection instruction from master station equipment A, communication between master station equipment A and slave station equipment a begins.

[0025] FIG. 5 is a timing chart illustrating the operation of a communication system including a plurality of master station devices and a plurality of slave station devices (comparative example).

[0026] When master station equipment A transmits CSCO[A] to slave station equipment a (S20), slave station equipment a transmits a connection request to master station equipment A using CSCI[a] in synchronization with master station equipment A (S21).

[0027] When master station device A instructs master station device A itself and slave station device a to transmit a communication signal using CSCO[A] (S22), slave station device a transmits an acknowledgement of the communication signal transmission to master station device A using CSCI[a] (S23).

[0028] Then, the master station device A transmits a communication signal [A] to the slave station device a (S24), and the slave station device a transmits a communication signal [a] to the master station device A (S25), whereby the master station device A and the slave station device a are in communication.

[0029] Similarly, parent station device B transmits a communication signal [B] to child station device b (S26), and child station device b transmits a communication signal [b] to parent station device B (S27), whereby parent station device B and child station device b are in communication.

[0030] Similarly, the master station device C transmits a communication signal [C] to the slave station device c (S28), and the slave station device c transmits a communication signal [c] to the master station device C (S29), thereby causing the master station device C and the slave station device c to be in communication.

[0031] Fig. 6 is a diagram (comparison example) schematically showing a connection example of the communication system shown in Fig. 5. Fig. 6(a) is a diagram schematically showing a connection result of the communication system shown in Fig. 5. Fig. 6(b) is a diagram schematically showing a connection that cannot be realized in the communication system shown in Fig. 5.

[0032] In the communication system (comparison example) shown in FIG. 5, as shown in FIG. 6(a), master station equipment A can be connected to slave station equipment a only through a line, master station equipment B can be connected to slave station equipment b only through a line, and master station equipment C can be connected to slave station equipment c only through a line.

[0033] Therefore, in the communication system (comparison example) shown in Fig. 5, the master station equipment B cannot establish a line connection with the slave station equipment a, as shown in Fig. 6(b). In other words, in the communication system (comparison example) shown in Fig. 5, the master station equipment and the slave station equipment are connected in a fixed one-to-one relationship.

[0034] Therefore, as described below, a communication system according to an embodiment is configured to efficiently connect multiple master station devices and multiple slave station devices simultaneously. For example, if the communication system according to an embodiment has multiple master station devices (A, B, C) and multiple slave station devices (a, b, c, d), each of the multiple slave station devices (a, b, c, d) is assumed to have a function for receiving a control signal (CSCO) from each of the multiple master station devices (A, B, C). In other words, each of the multiple slave station devices (a, b, c, d) can be connected to any of the multiple master station devices (A, B, C).

[0035] 7 is a functional block diagram illustrating functions of a master station device 10 included in a communication system according to an embodiment. The communication system according to an embodiment includes a plurality of master station devices 10 and a plurality of slave station devices, and the master station devices 10 and the slave station devices communicate efficiently one-to-one via, for example, a satellite 2 (see FIG. 1 ).

[0036] As shown in FIG. 7, the master station device 10 provided in the communication system according to one embodiment includes, for example, a storage unit 20, an antenna 21, a modem 22, a connection determination unit 23, a communication determination unit 24, a connection processing unit 25, and a control unit 26.

[0037] The antenna 21 is used for mutual communication with the slave station devices via, for example, a satellite, a relay device, etc. The modem 22 modulates and demodulates signals via the antenna 21 to realize communication with the slave station devices.

[0038] The connection determination unit 23 determines whether the parent station device 10 itself is connected to a child station device, and outputs the determination result to the communication determination unit 24 and the control unit 26. The connection determination unit 23 also determines whether another parent station device 10 in the communication system is connected to a child station device, and outputs the determination result to the communication determination unit 24 and the control unit 26.

[0039] The communication determination unit 24 determines whether the master station device 10 itself is currently communicating data with a slave station device, and outputs the determination result to the control unit 26. The communication determination unit 24 also determines whether another master station device 10 in the communication system is currently communicating data with a slave station device, and outputs the determination result to the control unit 26.

[0040] The connection processing unit 25 performs processing such as connecting one of the slave station devices that has newly requested connection to one of the master station devices 10, for a master station device 10 that is not currently connected to any of the slave station devices, based on the control of the control unit 26. The functions of the connection processing unit 25 will be described in detail after the description of the control unit 26 and the storage unit 20.

[0041] The control unit 26 has a restriction setting unit 260 and controls each unit constituting the parent station device 10. The restriction setting unit 260 sets a predetermined connection restriction time. The control unit 26 also processes information output by the modem 22, connection determination unit 23, and communication determination unit 24 using the storage unit 20.

[0042] The storage unit 20 has a connection status sharing unit 201 and a communication status sharing unit 202. The connection status sharing unit 201 shares connection status information indicating whether each of the multiple parent station devices 10 is currently connected to any of the child station devices with the other parent station devices 10. The communication status sharing unit 202 shares communication status information indicating whether each of the multiple parent station devices 10 is currently communicating data with any of the child station devices with the other parent station devices 10.

[0043] Then, based on the connection status information shared by the connection status sharing unit 201 with other parent station devices 10, the connection processing unit 25 performs processing to connect one of the child station devices that has newly requested connection to one of the parent station devices 10 to the parent station device 10 that is not currently connected to any of the child station devices.

[0044] Furthermore, based on the connection status information shared by the connection status sharing unit 201 with other parent station devices 10 and the communication status information shared by the communication status sharing unit 202 with other parent station devices 10, the connection processing unit 25 performs processing to disconnect a parent station device 10 that is currently connected to one of the child station devices but is not currently communicating data, and connect one of the child station devices that has newly requested a connection to one of the parent station devices 10.

[0045] Furthermore, after the predetermined connection limit time set by the above-mentioned limit setting unit 260 has elapsed, the connection processing unit 25 performs processing to disconnect the current connection of a parent station device 10 that is currently connected to one of the child station devices but is not currently communicating data, and connect one of the child station devices that has newly requested a connection to one of the parent station devices 10.

[0046] Each master station device 10 may share connection status information and communication status information via a network (such as Ethernet (registered trademark)) that interconnects multiple master station devices 10 by wire. Each master station device 10 may be configured so that its CSC modem acquires information from other master station devices 10 while switching CSCO. Each master station device 10 may also be equipped with two CSC modems: one for its own CSCO communication and one for a common CSC modem (for information sharing).

[0047] In this way, in the communication system according to one embodiment, a plurality of master station devices 10 and a plurality of slave station devices perform one-to-one communication, but there are no restrictions on the combinations of connections between the master station devices 10 and the slave station devices.

[0048] The master station device 10 included in the communication system according to one embodiment has an available master station device management function that determines (manages) whether or not it is connected to a slave station device, grasps the status of available master station devices 10 (master station devices 10 to which no slave station devices are connected) among other master station devices 10, and notifies the status to slave station device a.

[0049] The master station device 10 also has a data communication management function that determines (manages) whether or not it is currently in data communication with a slave station device to which it is connected, and grasps the status of an available master station device 10 (here, a master station device 10 that is not performing data communication with a slave station device) among other master station devices 10, and transmits this information to slave station device a.

[0050] The master station device 10 also has a time limit management function that manages the connection time limit between the master station device 10 and the slave station device. For example, if a connection time limit is set by the limit setting unit 260, the master station device 10 waits until the connection time limit has elapsed before disconnecting the line, even if an instruction to disconnect the line is received.

[0051] The master station device 10 also has a line forcible disconnection function that cuts off the connection with the slave station device during communication in accordance with a predetermined condition.

[0052] Hereinafter, when distinguishing between the multiple master station devices 10, they may be referred to as master station device A, master station device B, and master station device C to clarify that they are different devices.

[0053] Next, an example of the operation of a communication system according to an embodiment having a plurality of master station devices 10 and a plurality of slave station devices will be described. Fig. 8 is a flowchart showing an example of the operation of a communication system according to an embodiment in which a plurality of master station devices 10 and a plurality of slave station devices communicate with each other via a satellite 2.

[0054] In a communication system, slave station device a performs satellite capture (S100) and determines whether or not it is possible to receive the CSCO transmitted by master station device A (S102). If it is not possible to receive it (S102: No), it proceeds to processing S104, and if it is possible to receive it (S102: Yes), it proceeds to processing S106.

[0055] In the process of S104, the slave station device a waits until a master station device 10 with which it can communicate becomes available.

[0056] The slave station device a synchronizes with the master station device A and requests a line connection from the master station device A (S106), determines whether the master station device A is available (S108), and if the master station device A is available (S108: Yes), proceeds to processing of S110, and if the master station device A is not available (S108: No), proceeds to processing of S114.

[0057] Master station device A (or another master station device 10) permits connection to slave station device a using CSCO, instructs itself and slave station device a to send communication signals using CSCO (S110), and starts communication by transmitting communication signals to each other with slave station device a (S112).

[0058] In the processing of S114, the master station device A determines whether or not there is another available master station device 10, and if there is an available master station device 10 (S114: Yes), the processing proceeds to S116, and if there is no available master station device 10 (S114: No), the processing proceeds to S120.

[0059] In the process of S116, the master station device A transmits information indicating the available master station device 10 to the slave station device a by CSCO.

[0060] In the process of S118, the slave station equipment a transmits a line connection request in synchronization with the available master station equipment 10, and then the process proceeds to S110.

[0061] The processes of S114, S116, and S118 correspond to the above-mentioned available master station device management function.

[0062] In the processing of S120, the master station device A determines whether there is a master station device 10 that is connected but not communicating with a slave station device, and if there is a corresponding master station device 10 (S120: Yes), it proceeds to the processing of S122, and if there is no corresponding master station device 10 (S120: No), it returns to the processing of S104.

[0063] In the process of S122, the parent station device 10 that was found to be the case in the process of S120 determines whether or not a time limit has been set for the connection, and if there is a time limit (S122: Yes), proceeds to the process of S124, and if there is no time limit (S122: No), proceeds to the process of S126. The process of S122 corresponds to the time limit management function described above.

[0064] The parent station device 10 that was found to be the case in the process of S120 waits until the time limit elapses (S124), and then disconnects the line of the connected child station device (S126). The process of S126 corresponds to the above-mentioned line forcible disconnection function.

[0065] In the process of S128, the master station device A transmits information about the master station device 10 found to be matched in the process of S120 to the slave station device a by CSCO.

[0066] In the process of S130, the slave station equipment a synchronously requests the master station equipment 10 that was selected in the process of S120 to establish a line connection, and the process proceeds to the process of S110.

[0067] The processes from S120 to S130 correspond to the data communication management function described above.

[0068] 9A and 9B are diagrams illustrating a first operation example (available master station device management function) of a communication system according to an embodiment including multiple master station devices and multiple slave station devices. Fig. 9A is a diagram illustrating a state in which slave station device a transmits a connection request to connected master station device A. Fig. 9B is a diagram illustrating a state in which slave station device a transmits a CSCI in response to a CSCO from master station device C. Fig. 9C is a diagram illustrating a process in which master station device C and slave station device a start communication.

[0069] In Figure 9(a), master station equipment A is connected to slave station equipment b, and master station equipment B is connected to slave station equipment c. Slave station equipment a synchronously transmits a connection request to master station equipment A using CSCI. When master station equipment A receives the connection request from slave station equipment a, it determines whether master station equipment B and C are available, since it is connected to slave station equipment b. Master station equipment A then determines that master station equipment B is connected and master station equipment C is available.

[0070] 9B, master station equipment A notifies slave station equipment a by CSCO that master station equipment C is available. When slave station equipment a learns that master station equipment C is available, it synchronizes with master station equipment C and transmits a line connection request to master station equipment C by CSCI.

[0071] 9C, master station device C receives a connection request from slave station device a, permits connection to slave station device a, and instructs it to transmit a communication signal. When slave station device a transmits a communication signal in response to the connection instruction from master station device C, communication between master station device C and slave station device a begins.

[0072] FIG. 10 is a timing chart showing a first operation example (available master station device management function) of a communication system according to an embodiment that includes a plurality of master station devices and a plurality of slave station devices.

[0073] Master station equipment A transmits a communication signal [A] to slave station equipment b (S30), and slave station equipment b transmits a communication signal [b] to master station equipment A (S31), and master station equipment A and slave station equipment b are in communication.

[0074] Similarly, master station device B transmits a communication signal [B] to slave station device c (S32), and slave station device c transmits a communication signal [c] to master station device B (S33), and master station device B and slave station device c are in communication.

[0075] Furthermore, master station device B notifies master station device A that it is communicating via CSCO[B] (S34), and master station device C notifies master station device A that it is idle via CSCO[C] (S35). In other words, master station device A knows that master station devices A and B are communicating, and that master station device C is idle.

[0076] The slave station equipment a transmits a connection request to the master station equipment A using CSCI[a] in synchronization with the master station equipment A (S36).

[0077] Master station equipment A notifies slave station equipment a by CSCO[A] that master station equipment C is available (S37).

[0078] The slave station device a receives the CSCO[C] transmitted by the master station device C (S38), and transmits a connection request to the master station device C by using the CSCI[a] in synchronization with the master station device C (S39).

[0079] Master station device C instructs itself (satellite return) and slave station device a to transmit a communication signal by CSCO[C] (S40).

[0080] Then, the master station device C transmits a communication signal [C] (S41), and the slave station device a transmits a communication signal [a] (S42), so that the line from the master station device C to the slave station device a is in communication.

[0081] 11A and 11B are diagrams illustrating a second operation example (data communication management function) of a communication system according to an embodiment, which includes multiple master station devices and multiple slave station devices. Fig. 11A is a diagram illustrating a state in which a slave station device a transmits a connection request to a connected master station device A. Fig. 11B is a diagram illustrating a state in which the master station device A grasps the data communication status of other master station devices 10 by CSCO. Fig. 11C is a diagram illustrating a state in which the master station device A transmits an instruction to the master station device C to disconnect the connection.

[0082] 11A, slave station equipment a synchronously transmits a connection request to master station equipment A using CSCI. However, master station equipment A is currently connected to slave station equipment b with data communication, and master station equipment B is currently connected to slave station equipment c with data communication. Furthermore, master station equipment C is currently connected to slave station equipment d, but data communication is not taking place. In other words, there is no master station equipment 10 to which a slave station equipment is not connected.

[0083] 11B, when master station equipment A receives a connection request from slave station equipment a, it determines whether master station equipment B and C are available because it is currently connected to slave station equipment b. At this time, master station equipment B notifies master station equipment A that it is currently connected with data communication. Master station equipment C notifies master station equipment A that it is currently connected but is not currently performing data communication.

[0084] As a result, master station device A learns that master station device B is connected with data communication, and master station device C is connected but is not conducting data communication. Slave station device A waits for instructions from master station device A.

[0085] 11(C), master station equipment A notifies slave station equipment a by CSCO that master station equipment C is not performing data communication. Master station equipment A also sends a command to master station equipment C to disconnect from slave station equipment d. Slave station equipment d acknowledges to master station equipment C that the connection will be disconnected. At this point, master station equipment C and slave station equipment d are still connected.

[0086] 12A and 12B are diagrams schematically illustrating a third operation example (a time limit management function and a line forced disconnection function accompanied by a data communication management function) of a communication system according to an embodiment including multiple master station devices and multiple slave station devices. Fig. 12A is a diagram schematically illustrating a state in which master station device C disconnects the connection with slave station device d after a predetermined connection time limit has elapsed. Fig. 12B is a diagram schematically illustrating a state in which slave station device a transmits a connection request to master station device C using CSCI. Fig. 12C is a diagram schematically illustrating a state in which master station device C and slave station device a start communication.

[0087] 12A, master station equipment A is connected to slave station equipment b, and master station equipment B is connected to slave station equipment c. If a predetermined connection time limit is set, master station equipment C will disconnect from slave station equipment d after the predetermined connection time limit has elapsed (time limit management function and line forced disconnection function).

[0088] 12B, master station equipment A notifies slave station equipment a by CSCO that master station equipment C is available. When slave station equipment a learns that master station equipment C is available, it synchronizes with master station equipment C and transmits a line connection request to master station equipment C by CSCI.

[0089] 12(c), master station device C receives a connection request from slave station device a, permits connection to slave station device a, and instructs it to transmit a communication signal. When slave station device a transmits a communication signal in response to the connection instruction from master station device C, communication between master station device C and slave station device a begins.

[0090] FIG. 13 is a timing chart showing a second operation example (data communication management function) and a third operation example (time limit management function and forced line disconnection function accompanied by the data communication management function) of a communication system according to an embodiment that includes multiple parent station devices and multiple child station devices.

[0091] Master station device A transmits a communication signal [A] to slave station device b (S50), and slave station device b transmits a communication signal [b] to master station device A (S51), and master station device A and slave station device b are in communication. At this time, master station devices A, B, and C share connection status information and communication status information indicating that master station device A and slave station device b are connected and conducting data communication.

[0092] Similarly, master station device B transmits a communication signal [B] to slave station device c (S52), and slave station device c transmits a communication signal [c] to master station device B (S53), and master station device B and slave station device c are in communication.

[0093] Furthermore, master station device C transmits a communication signal [C] to slave station device d (S54), and slave station device d transmits a communication signal [d] to master station device C (S55), and master station device C and slave station device d are now in communication.

[0094] Master station device B transmits connection status information and communication status information indicating that it is connected to slave station device c with data communication to master station device A via CSCO[B] (S56). Master station device C transmits connection status information and communication status information indicating that master station device C and slave station device d are connected but not communicating data to master station device A via CSCO[C] (S57). Thus, master station device A knows that master station device B is connected to slave station device c with data communication, and that master station device C and slave station device d are connected but not communicating data.

[0095] The slave station equipment a transmits a connection request to the master station equipment A using CSCI[a] in synchronization with the master station equipment A (S58).

[0096] Since master station equipment A is currently connected to slave station equipment b with data communication, it instructs slave station equipment a to wait by CSCO[A] (S59). Then, master station equipment A instructs master station equipment C by CSCO[A] to cut off the connection with slave station equipment b (S60).

[0097] The master station device C notifies the slave station device d by CSCO[C] that the connection will be cut off after a predetermined connection time limit has elapsed (S61).

[0098] The slave station device d transmits a CSCI[d] to the master station device C indicating that it understands that the connection will be cut off after a predetermined connection time limit has elapsed (S62).

[0099] After a predetermined connection time limit has elapsed, the master station device C instructs the slave station device d to disconnect the connection using CSCO[C] (S63).

[0100] When the slave station device d transmits an acknowledgement of the disconnection to the master station device C by using CSCI[d] (S64), the master station device C disconnects the connection with the slave station device d.

[0101] Master station equipment A notifies slave station equipment a by CSCO[A] that master station equipment C is available (S65).

[0102] The slave station device a receives the CSCO[C] transmitted by the master station device C (S66), and transmits a connection request to the master station device C by using the CSCI[a] in synchronization with the master station device C (S67).

[0103] Master station device C instructs itself (satellite return) and slave station device a to transmit a communication signal by CSCO[C] (S68).

[0104] The slave station device a transmits an acknowledgement of the communication signal transmission to the master station device C by using CSCI[a] (S69).

[0105] Then, the master station device C transmits a communication signal [C] to the slave station device a (S70), and the slave station device a transmits a communication signal [a] to the master station device C (S71), thereby putting the line from the master station device C to the slave station device a into communication.

[0106] In this way, in one embodiment of the communication system having a plurality of parent station devices 10 and a plurality of child station devices, each parent station device 10 performs processing to connect one of the child station devices that has newly requested connection to one of the parent station devices 10 to a parent station device 10 that is not currently connected to any of the child station devices, based on the connection status information shared by the connection status sharing unit 201, thereby enabling a plurality of parent station devices 10 to be efficiently connected simultaneously to a plurality of child station devices.

[0107] In addition, each function of the parent station device 10 and the child station device may be configured in part or in whole by hardware such as a programmable logic device (PLD) or a field programmable gate array (FPGA), or may be configured as a program executed by a processor such as a CPU.

[0108] For example, the master station device 10 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0109] 14 is a diagram illustrating an example of a hardware configuration of a master station device 10 according to an embodiment. As illustrated in FIG. 14 , the master station device 10 has, for example, an input unit 50, an output unit 51, a communication unit 52, a CPU 53, a memory 54, and an HDD 55 connected via a bus 56, and functions as a computer. The master station device 10 is also configured to input and output data to and from a computer-readable storage medium 57.

[0110] The input unit 50 is, for example, a keyboard and a mouse. The output unit 51 is, for example, a display device such as a display that outputs images. The communication unit 52 is, for example, a wired or wireless network interface, and may have a function as an output unit that outputs data to the outside.

[0111] The CPU 53 controls each component of the master station device 10 and performs predetermined processing, etc. The memory 54 and HDD 55 are storage units that store data, etc.

[0112] The storage medium 57 is capable of storing programs and the like that cause the master station device 10 to execute the functions of the master station device 10. The architecture that configures the master station device 10 is not limited to the example shown in FIG.

[0113] Next, another example of the configuration of a communication system according to an embodiment will be described. Fig. 15 is a diagram illustrating an overview of another example of the configuration of a communication system according to an embodiment (communication system 1a). The communication system 1a has the functions of multiple master station devices installed at a base 30 and multiple slave station devices installed at bases 40a, 40b, 40c, and 40d, respectively.

[0114] Specifically, the base station 30 has base station antennas 31A, 31B, and 31C, base station modems 32A, 32B, and 32C, a Layer 3 switch 33, an IP telephone conference terminal 34, and a SIP server 35, and has the functions of multiple base station devices.

[0115] Furthermore, each part of the base 30 is connected by Ethernet (registered trademark) or the like, and the parts constituting the plurality of parent station devices are able to share connection status information and communication status information.

[0116] The base station 40a has a slave station antenna 41a, a slave station modem 42a, a layer 2 switch 43a, and an IP telephone conference terminal 44a, and transmits and receives control signals and data communication signals (Up / Down: each 128 kbps) to and from the base station 30 via the satellite 2. The base stations 40b, 40c, and 40d are configured in the same manner as the base station 40a.

[0117] The communication system 1a performs the above-described processing, and for example, the bases 40a, 40b, and 40c communicate efficiently with the base 30 having the functions of a plurality of master station devices.

[0118] It should be noted that the functions performed by the components described herein may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to perform the described functions.

[0119] A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may be a programmed processor that executes programs stored in memory.

[0120] In this specification, a circuitry, unit, or means is hardware that is programmed to realize or performs the described functions, which may be any hardware disclosed herein or any hardware known to be programmed to realize or perform the described functions.

[0121] If the hardware is a processor considered to be a type of circuitry, the circuitry, means, or unit is a combination of the hardware and software used to configure the hardware and / or processor.

[0122] 1, 1a... communication system, 2... satellite, 10... master station device, 20... storage unit, 21... antenna, 22... modem, 23... connection determination unit, 24... communication determination unit, 25... connection processing unit, 26... control unit, 30... base, 31A, 31B, 31C... master station antenna, 32A, 32B, 32C... master station modem, 33... Layer 3 switch, 34... IP telephone conference terminal, 35... SIP server, 40a, 40b, 40c, 40d... base, 4 1a, 41b, 41c, 41d...Slave station antennas, 42a, 42b, 42c, 42d...Slave station modems, 43a, 43b, 43c, 43d...Layer 2 switches, 44a, 44b, 44c, 44d...IP telephone conference terminals, 50...Input unit, 51...Output unit, 52...Communication unit, 53...CPU, 54...Memory, 55...HDD, 56...Bus, 57...Storage medium, 201...Connection status sharing unit, 202...Communication status sharing unit, 260...Restriction setting unit

Claims

1. A communication system comprising a plurality of parent station devices and a plurality of child station devices, each of which communicates one-to-one with the other, characterized in that each of the parent station devices has: a connection status sharing unit which shares connection status information indicating whether each of the parent station devices is currently connected to any of the child station devices; and a connection processing unit which, based on the connection status information shared by the connection status sharing unit, performs processing to connect one of the child station devices that has newly requested a connection to one of the parent station devices to a parent station device that is not currently connected to any of the child station devices.

2. The communication system according to claim 1, wherein each of the parent station devices further comprises a communication status sharing unit which shares communication status information indicating whether each of the parent station devices is currently in data communication with any of the child station devices, and the connection processing unit performs processing to disconnect a parent station device which is connected to any of the child station devices but not in data communication, and connect any of the child station devices which has newly requested a connection to any of the parent station devices, based on the connection status information shared by the connection status sharing unit and the communication status information shared by the communication status sharing unit.

3. The communication system according to claim 2, wherein each of the parent station devices further comprises a restriction setting unit that sets a predetermined connection restriction time, and the connection processing unit performs processing to disconnect a parent station device that is currently connected to one of the child station devices but is not communicating data after the predetermined connection restriction time set by the restriction setting unit has elapsed, and to connect one of the child station devices that has newly requested a connection to one of the parent station devices.

4. A communication system according to claim 3, characterized in that each of the master station devices shares connection status information and communication status information via a network that mutually connects the plurality of master station devices by wire.

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