JP2010278662A - Communication system, communication method, control station terminal station and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use time slot and perform high-reliability data communications, in a configuration which has a control station that transmits data and a plurality of terminal stations that relay the data among each station. <P>SOLUTION: In a communication system that has the control station which transmits data for each frame and the plurality of terminal stations, the terminal station assigned with a transmission right for each time slot in a frame relays and transmits data that are transmitted from the control station. The control station transmits data to the plurality of terminal stations for each frame, and checks the state of relay transmission of the terminal station which has the transmission right for each time slot, and depending on the check result, the control station retransmits data, among the time slots where states of relay transmission are checked. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication system, a communication method, a control station, a terminal station, and a program.

  A technique for performing stable data communication between terminal stations is known. For example, a technique for providing a plurality of communication paths between terminal stations and a technique for operating a terminal station that is not a dedicated relay station as a relay station are known. In addition, for example, a technique for transmitting the same data a plurality of times in order to improve the reliability of the transmission data is also known.

  When communication with high reliability is required, for example, a large reception buffer is set so that data for a certain time can be accumulated. Then, the accumulated data is transmitted after being delayed, and is recovered by executing retransmission within the delay time. Alternatively, the data rate is reduced.

  However, for example, when communicating real-time traffic stream data, since the data rate is fixed and low delay and constant delay are required, high reliability cannot be ensured by the above-described method.

  There is a technique in which the same stream data is multiplexed and transmitted by frequency multiplexing, code multiplexing, or polarization multiplexing, and data having a good reception state is selectively received on the receiving side. In this case, communication quality can be maintained high, but communication must be performed using redundant communication paths. Also, a technique for improving the radio signal strength between terminal stations in order to realize a high communication rate is known (see Patent Document 1). In this case, for example, on the transmitting side, data is transmitted to a plurality of receiving sides using wide directional antennas, and on the receiving side, the directional beam is directed to the transmitting side using narrow directional antennas, and from the transmitting side. Receive data.

  In recent years, wireless has come to be used for communication between home information devices. As a method for realizing communication between such information devices easily and with high quality, for example, a technique of relay transmission using a plurality of communication paths by a time division method is known. In communication between information devices in a home, stream data such as video data and audio data requiring real-time properties is often handled. For example, there are a home theater system in which multi-channel speakers are arranged, a multi-camera system in which a large number of network cameras are arranged, and the like.

  In a home theater system or the like, even if the state of the communication path changes, it is necessary for all terminals on the network to receive data with high communication quality. Therefore, even in the case of such a time division method, there is an increasing need to perform data communication with lower delay and constant delay by suppressing data retransmission due to an error occurrence or the like.

JP 2004-364287 A

  In order to control the redundancy of relay data, a wireless communication technique having a plurality of communication paths is known. In this technique, the terminal station performs redundant transmission of data received from a plurality of control stations using a plurality of communication paths. This is because the redundancy of transmission data in each communication path is kept optimal and error tolerance is improved.

  Here, for example, in a home theater system or the like, there is one transmission side for broadcast transmission, while there are a plurality of reception sides. All terminal stations establish synchronization with the control station that is the data transmission source, and receive data from the control station. Each terminal station relays and transmits the received data to other terminal stations. Then, for each time slot, the combination of the direction of the received beam and the terminal station that performs relay transmission is switched. This ensures data redundancy.

  However, if reception of data from the control station fails or reception of relayed data fails, the terminal station cannot perform relay transmission in its own time slot. In this case, the number of relay transmission HOPs may be reduced in a chain.

  This state will be specifically described with reference to FIG. The control station 705 transmits data in the first frame 700 shown in FIG. Thereafter, each terminal station 701 to 704 performs relay transmission in time slots 707 to 710. As a result, when the end of the frame 700 is reached, each terminal station 701 to 704 can acquire data from five different HOPs including the control station, and highly reliable redundant transmission is ensured.

  However, in the next frame 716, the terminal stations 702 and 703 have failed to receive data transmitted from the control station in the time slot 711 at the head of the frame. For this reason, the terminal station 702 has a transmission right in the next time slot 712, but cannot perform relay transmission. Also, the terminal station 703 cannot perform relay transmission in the time slot 713 to which the terminal station has a transmission right. In this case, the number of HOPs at each terminal station is 2HOP or 3HOP, and the communication reliability is significantly reduced. That is, the number of empty slots through which no data is communicated increases, and the effective data for redundant transmission decreases significantly.

  Accordingly, the present invention has been made in view of the above problems, and in a configuration having a control station that transmits data and a plurality of terminal stations that relay the data between the terminal stations, the time slot is effectively used. The purpose is to realize highly reliable data communication.

  In order to solve the above-described problem, an aspect of the present invention includes a control station that transmits data for each frame and a plurality of terminal stations, and a transmission right is assigned to each time slot in the frame. A terminal station that relays data from a control station, the control station transmitting means for transmitting data to the plurality of terminal stations for each frame, and a transmission right for each time slot. Confirmation means for confirming a state of relay transmission by a terminal station having a transmission means, and retransmission means for retransmitting data during a time slot in which the state of relay transmission is confirmed according to a result of confirmation by the confirmation means It is characterized by doing.

  According to the present invention, in a configuration having a control station that transmits data and a plurality of terminal stations that relay the data between the terminal stations, the time slot is effectively used to realize highly reliable data communication. it can.

The figure which shows an example of the whole structure of the communication system concerning one embodiment of this invention. The figure which shows an example of a structure of the flame | frame used by the communication system shown in FIG. The figure which shows an example of a functional structure of the control station 10 and the terminal station 20 which are shown in FIG. 3 is a flowchart showing an example of a process flow in the control station 10 shown in FIG. 1. The flowchart which shows an example of the flow of a process in the terminal station 20 shown in FIG. The figure which shows an example of the outline | summary of the communication processing in the communication system shown in FIG. 9 is a flowchart illustrating an example of a process flow in the control station 10 according to the second embodiment. 9 is a flowchart illustrating an example of a process flow in a terminal station 20 according to the second embodiment. FIG. 9 is a diagram illustrating an example of an outline of communication processing in a communication system according to a second embodiment. The figure which shows an example of a prior art.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a diagram showing an example of the overall configuration of a communication system according to an embodiment of the present invention.

  In this communication system, a control station 10 and a plurality of terminal stations 20 (terminal stations 20a to 20d) are connected via a network constituted by a wireless local area network (LAN) or the like. The control station and each terminal station only need to be able to communicate with each other, and need not necessarily communicate via a wireless LAN.

  The control station 10 transmits data to a plurality of terminal stations 20 for each frame. The terminal station 20 receives data transmitted from the control station 10. When the terminal station 20 has successfully received data, the terminal station 20 relays and transmits the data to another terminal station in a time slot in the frame.

  Here, the relay transmission is performed based on time slot information preset by the control station 10 (hereinafter referred to as time slot information). The time slot information is information that defines in which time slot each terminal station 20 acquires the transmission right and performs relay transmission. For example, in the case of FIG. 1, the control station 10 has the transmission right in the first time slot, and each terminal station 20 has the transmission right in the order of the terminal station 20a and the terminal station 20c in the subsequent time slots. is doing. In FIG. 1, the terminal station 20a succeeds in data reception, and the terminal stations 20b and 20c fail in data reception. Therefore, after data transmission by the control station 10, the terminal station 20a that first obtains the transmission right relays and transmits data to other terminal stations.

  The above is an explanation of an example of the overall configuration of the communication system according to the present embodiment. A computer is incorporated in the control station 10 and the terminal station 20 described above. The computer includes main control means such as a CPU, and storage means such as ROM (Read Only Memory), RAM (Random Access Memory), and HDD (Hard Disk Drive). In addition, the computer may further include input / output means such as buttons, a display, or a touch panel, and communication means such as a network card. These components are connected by a bus or the like, and are controlled by the main control unit executing a program stored in the storage unit.

  Here, an example of a frame configuration used in the communication system shown in FIG. 1 will be described with reference to FIG.

  One frame 50 is divided into a plurality of time slots. In each of the time slots 51 to 55, data transmission, relay transmission, or the like is performed in the order assigned in advance.

  In the time slot 51, the control station 10 has a transmission right. Therefore, in the time slot 51, the control station 10 performs data transmission. During this period, each terminal station 20 receives data from the control station 10 with the directivity of the receiving beam antenna directed toward the control station 10. Each terminal station 20 receives time slot information from the control station 10 before the frame 50 starts, and grasps the time slot assigned to the own station based on the information. Thereby, each terminal station 20 grasps its own transmission right and performs relay transmission. In the case of the example illustrated in FIG. 2, the time slot is associated with one of the control station 10 and the terminal station 20 on a one-to-one basis, but the present invention is not limited to this. For example, a plurality of time slots may be assigned to the same terminal station.

  Here, the relay transmission time slot allocated to each terminal station 20 includes a carrier detection period 56 and a data transmission period 57. The carrier detection period 56 is a period in which the control station 10 or the terminal station 20 confirms the state (presence / absence) of relay transmission by the terminal station 20 having the transmission right in the time slot. The terminal station 20 having the transmission right starts data transmission in the carrier detection period 56. The control station 10 or another terminal station 20 performs carrier sense during the carrier detection period 56 and confirms whether or not the terminal station 20 having the transmission right relays data. The data transmission period 57 is a period for transmitting relay data.

  Next, an example of a functional configuration of the control station 10 and the terminal station 20 illustrated in FIG. 1 will be described with reference to FIG.

  First, the configuration of the control station 10 will be described with reference to FIG. The control station 10 includes an RF (Radio Frequency) unit 900, a BBP (Base Band Processor) 901, a MAC (Medium Access Controller) 902, and a transmission signal generation unit 903. The MAC unit 902 manages the media access layer, and the BBP unit 901 performs communication signal processing such as error correction coding, decoding, and modulation / demodulation. The RF unit 900 processes a baseband signal into a carrier frequency band signal. The transmission signal generation unit 903 generates a transmission signal.

  Here, the RF unit 900 is provided with a transmission beam antenna 906 and a reception beam antenna 908. For the transmission beam antenna 906 and the reception beam antenna 908, for example, a phased array method in which directivity can be changed electronically or a switching method of a plurality of directional antennas can be adopted, and the directivity can be changed. . Further, the RF unit 900 is provided with an omni-pattern transmitting antenna 905 and an omni-pattern receiving antenna 907 having wide directivity (hereinafter referred to as an omni pattern).

  That is, the transmission beam antenna 906 and the reception beam antenna 908 function as a first antenna having directivity at a predetermined angle. The omni-pattern transmission antenna 905 and the omni-pattern reception antenna 907 function as a second antenna having directivity at a wider angle than the transmission beam antenna 906 and the reception beam antenna 908. The RF unit 900 further includes directivity control units 909 and 910 that control the directivity of the antenna, a transmission RF circuit 911, and a reception RF circuit 912.

  The BBP unit 901 is provided with a modulation circuit 913 that modulates transmission data and a demodulation circuit 914 that demodulates reception data.

  The MAC unit 902 includes a carrier detection unit 915, a transmission control unit 916, a time slot setting unit 917, a position detection unit 918, and a storage unit 919. The carrier detection unit 915 confirms the relay transmission state (carrier sense) of the terminal station 20. This confirmation is performed for a predetermined detection period (carrier detection period 56 shown in FIG. 2) from the time slot start time.

  The transmission control unit 916 controls data transmission. Transmission control section 916 also performs data retransmission control based on the detection result by carrier detection section 915. The time slot setting unit 917 sets a time slot. The position detection unit 918 detects the position of each terminal station 20 based on a search request (DISCOVERY) or the like from each terminal station 20. For example, when the position detection unit 918 receives a search request from the terminal station 20, the position detection unit 918 detects a direction (for example, an angle) with the strongest intensity of the received signal as the position of the terminal station 20. The storage unit 919 stores various setting information and the like.

  Next, the configuration of the terminal station 20 will be described with reference to FIG. The terminal station 20 includes an RF unit 1000, a BBP unit 1001, a MAC unit 1002, and a received signal processing unit 1003. The received signal processing unit 1003 processes received data received from the control station 10. The RF unit 1000 performs the same function as the RF unit 900 described above, and the BBP unit 1001 performs the same function as the BBP unit 901 described above. Therefore, the description is omitted here. For example, the transmitting beam antenna 1006 and the receiving beam antenna 1008 function as first terminal station side antennas having directivity at a predetermined angle. The omni-pattern transmission antenna 1005 and the omni-pattern reception antenna 1007 function as a second terminal station side antenna having directivity at a wider angle than the transmission beam antenna 1006 and the reception beam antenna 1008.

  The MAC unit 1002 includes a carrier detection unit 1015, a redundancy control unit 1016, a relay control unit 1017, a position detection unit 1018, and a storage unit 1019. The carrier detection unit (terminal station side detection unit) 1015 confirms the relay transmission state of the terminal station 20. This confirmation is performed for a predetermined detection period (carrier detection period 56 shown in FIG. 2) from the time slot start time.

  The redundancy control unit 1016 processes data acquired from a plurality of paths. A relay control unit (terminal station side control unit) 1017 controls relay transmission. For example, the relay control unit 1017 determines the antenna control state in the next time slot based on the detection result by the carrier detection unit 1015. The position detection unit 1018 detects the positions of the terminal stations 20 and the control station 10 based on a search request (DISCOVERY) from each terminal station 20, data transmission from the control station 10, and the like. The storage unit 1019 stores various setting information and the like.

  FIG. 4 is a flowchart showing an example of a process flow in the control station 10 shown in FIG. Here, the control station 10 will be described assuming that the position detection unit 918 already knows the position of each terminal station.

  In the time slot setting unit 917, the control station 10 assigns a time slot for each terminal station 20 to perform relay transmission to each terminal station 20. Then, the information (time slot information) is transmitted to each terminal station 20 (S101). When the first time slot starts, the control station 10 transmits data using the omni-pattern transmission antenna 905 (S102).

  After the data transmission, the control station 10 directs the directivity of the receiving beam antenna 908 in the direction of the terminal station 20 having the transmission right in the time slot for each relay transmission time slot (S103). Then, the reception operation is performed during the carrier detection period 56 shown in FIG. Thereby, the control station 10 confirms the relay transmission state (S104). As a result, if relay transmission can be confirmed (YES in S105), the control station 10 enters a WAIT state until the next time slot starts.

  On the other hand, when the relay transmission cannot be confirmed (NO in S105), the control station 10 directs the directivity of the transmission beam antenna 906 toward the terminal station 20 having the transmission right in the time slot (S106). Then, the data transmitted in the time slot at the head of the frame (that is, the data transmitted in S102) is retransmitted toward the terminal station 20 (S107). Thereafter, the control station 10 repeats the same operation for each relay transmission time slot (NO in S108). When all the relay transmission time slots are over (YES in S108), this process ends.

  FIG. 5 is a flowchart showing an example of the processing flow in the terminal station 20 shown in FIG. Here, it is assumed that each terminal station already knows the positions of the control station 10 and each terminal station 20 in the position detection unit 1018.

  The terminal station 20 receives (acquires) time slot information from the control station 10 (S201). That is, the terminal station 20 obtains this time slot information, thereby grasping a transmission time slot in which data is transmitted by the control station 10 and a relay transmission time slot in which the own station transmits data.

  In the first time slot (ie, transmission time slot), the terminal station 20 directs the directivity of the receiving beam antenna 1008 toward the control station 10 (S202). Thereby, the terminal station 20 receives the data transmitted by the control station 10 (S203).

  The terminal station 20 determines whether it is the time slot of its own station for every relay transmission time slot. This determination is made based on the time slot information acquired in S201. As a result of the determination, if it is not the time slot of the own station (NO in S204), the terminal station 20 directs the directivity of the receiving beam antenna 1008 in the direction of the other terminal station 20 and shifts to the receiving operation (S205). . Here, the other terminal station 20 refers to a terminal station that performs relay transmission in the time slot (that is, a relay station). Thereby, it tries to receive data relay-transmitted by another terminal station 20 (S206). Thereafter, the terminal station 20 proceeds to the process of S211.

  If it is determined in S204 that the time slot is the own station (YES in S204), the terminal station 20 determines whether or not data necessary for relay transmission has been received. If the data is not received as a result of the determination (NO in S207), the terminal station 20 directs the directivity of the receiving beam antenna 1008 toward the control station 10 (S209). This attempts to receive data retransmitted by the control station 10 (S210). Thereafter, the terminal station 20 proceeds to the process of S211.

  On the other hand, if the data has been received (YES in S207), the terminal station 20 transmits the relay data using the omni-pattern transmission antenna 1005 (S208). Thereafter, the terminal station 20 repeats the same operation for each relay transmission time slot (NO in S211). When all the relay transmission time slots are over (YES in S211), this process is finished.

  Here, an example of an outline of communication processing in the communication system shown in FIG. 1 will be described with reference to FIG. Here, it is assumed that a station with a circle in each time slot has a transmission right. That is, in the case of the frame 800, the control station 10 has the transmission right in the time slot 806, and the terminal station 20b has the transmission right in the subsequent time slot 807.

  In the first time slot 806, the control station 10 transmits data to all the terminal stations 20 using the omni-pattern transmission antenna 905. In this case, the terminal station 20a and the terminal station 20c normally receive data, and the terminal station 20b and the terminal station 20d cannot receive data normally.

  In the next time slot 807, the terminal station 20b has the transmission right. However, since the terminal station 20b cannot receive data normally, it cannot shift to the relay transmission operation. Therefore, the terminal station 20b directs the directivity of the reception beam antenna 1008 in the direction of the control station 10 and shifts to the reception state.

  On the other hand, after transmitting data in the transmission time slot 806, the control station 10 directs the directivity of the receiving beam antenna 908 in the direction of the terminal station 20b. And the control station 10 confirms transmission of the relay data by the terminal station 20b during a carrier detection period. As a result, when it is confirmed that the terminal station 20b has not shifted to the relay transmission operation, the control station 10 directs the directivity of the transmission beam antenna 906 in the direction of the terminal station 20b, and transmits in the first time slot 806. Re-send the data. In this retransmission, both the control station 10 and the terminal station 20 perform communication using a beam antenna with high directivity gain. Therefore, communication with higher communication quality is performed as compared with the case where data transmitted using a normal omni-pattern transmission antenna is received.

  Here, in the first time slot 806, the terminal station 20d that failed to acquire data from the control station 10 transmits the data relayed and transmitted by the terminal station 20c before the relay transmission time slot assigned to the terminal station 20d starts. Receive. Thereby, the terminal station 20d has completed data acquisition. Therefore, the terminal station 20d performs relay transmission of data as usual in its own time slot.

  In the first time slot 811 of the next frame 801, the control station 10 transmits data to all terminal stations 20 using the omni-pattern transmission antenna 905. In this case, the terminal stations 20c and 20d cannot acquire this data. Also, the terminal stations 20c and 20d have failed to acquire data in the subsequent relay transmission time slot 812.

  Therefore, the terminal station 20c cannot perform relay transmission in the next time slot 813. Therefore, the terminal station 20c directs the directivity of the receiving beam antenna 1008 in the direction of the control station 10 and shifts to the reception state. Thereby, the terminal station 20c acquires data from the control station 10 by communication between the beam antennas.

  Here, the terminal station 20d cannot acquire data even after the time slot 813 and the time slot 814 have ended. Thereafter, when the time slot 815 in which the terminal station 20d has the transmission right is reached, the terminal station 20d cannot shift to the relay transmission operation because data is not acquired. Therefore, similarly to the terminal station 20c described above, data is acquired from the control station 10 by communication between the beam antennas. Therefore, data transmission can be performed without omission to all the terminal stations in the frame.

  As described above, according to the first embodiment, in a configuration including a control station that transmits data and a plurality of terminal stations that relay the data between the terminal stations, the terminal station performs relay transmission because data is not received. This time slot can be used effectively even if it cannot be performed.

  That is, it is possible to improve the reliability of redundant transmission (because the reduction in redundancy can be reduced) in order to effectively use time slots and prevent a significant decrease in the number of HOPs. Further, even in an environment where it is difficult to apply a retransmission procedure (for example, an environment that handles real-time traffic stream data having a strict data validity period), highly reliable data communication can be realized.

(Embodiment 2)
Next, Embodiment 2 will be described. FIG. 7 is a flowchart illustrating an example of a processing flow in the control station 10 according to the second embodiment. In addition, since the process from S301 to S305 is the same as the process from S101 to S105 described in the first embodiment, the process after S306 will be described here.

  In the processing of S305, the control station 10 confirms the relay transmission state in the carrier detection unit 915. As a result, if relay transmission can be confirmed (YES in S305), the control station 10 enters the WAIT state until the next time slot is started.

  On the other hand, when the relay transmission cannot be confirmed (NO in S305), the control station 10 transmits data using the omni-pattern transmission antenna 905 (S306). Thereafter, the control station 10 repeats the same operation for each relay transmission time slot (NO in S307). When all the relay transmission time slots are over (YES in S307), this process ends.

  FIG. 8 is a flowchart illustrating an example of a process flow in the terminal station 20 according to the second embodiment. In S404, it is determined whether or not the current time slot is a time slot assigned to the own station. If the current time slot is the own time slot, the process is the same as in FIG. 5 describing the first embodiment. Therefore, the description thereof is omitted here.

  In S404, the terminal station 20 determines in the relay control unit 1017 whether or not the current time slot is a time slot allocated to the own station. As a result of the determination, if it is not the time slot of the own station (NO in S404), the terminal station 20 directs the directivity of the receiving beam antenna 1008 in the direction of the other terminal station 20 (that is, the relay station) and performs the reception operation. (S405). As a result, the terminal station 20 attempts to receive data relayed and transmitted by another terminal station 20 having a transmission right (S406).

  Here, if the relay transmission from the other terminal station 20 can be confirmed (YES in S407), the terminal station 20 receives the data relayed by the other terminal station 20 (S408), and then proceeds to the process of S415. . On the other hand, if the relay transmission from the other terminal station 20 cannot be confirmed (NO in S407), the terminal station 20 directs the directivity of the receiving beam antenna 1008 in the direction of the control station 10 (S409). (S410). Thereafter, the terminal station 20 proceeds to the process of S415. Thereafter, the terminal station 20 repeats the same operation for each relay transmission time slot (NO in S415). When all the relay transmission time slots are over (YES in S415), this process ends.

  Here, an example of an outline of communication processing in the communication system according to the second embodiment will be described with reference to FIG. Here, as in FIG. 6, it is assumed that a station with a circle in each time slot has a transmission right.

  In the first time slot 606, the control station 10 transmits data to all the terminal stations 20 using the omni-pattern transmission antenna 905. In this case, the terminal station 20a and the terminal station 20c normally receive data, and the terminal station 20b and the terminal station 20d cannot receive data normally.

  In the next time slot 607, the terminal station 20b has the transmission right. However, since the terminal station 20b cannot receive data normally, it cannot shift to the relay transmission operation. Therefore, the terminal station 20b directs the directivity of the reception beam antenna 1008 in the direction of the control station 10 and shifts to the reception state.

  On the other hand, after transmitting data in the transmission time slot 606, the control station 10 directs the directivity of the receiving beam antenna 908 in the direction of the terminal station 20b. Then, the control station 10 confirms transmission of relay data by the terminal station 20b during the carrier detection period. As a result, when it is confirmed that the terminal station 20b has not shifted to the relay transmission operation, the control station 10 retransmits data using the omni-pattern transmission antenna 905.

  Here, in the first time slot 606, the terminal station 20d that failed to acquire data from the control station 10 retransmits the data retransmitted by the control station 10 before the relay transmission time slot assigned to the terminal station 20d starts. Receive. Thereby, the terminal station 20d has completed data acquisition. Therefore, the terminal station 20d performs relay transmission of data as usual in its own time slot.

  In the first time slot 611 of the next frame 601, the control station 10 transmits data to all the terminal stations 20 using the omni-pattern transmission antenna 905. In this case, the terminal stations 20c and 20d cannot acquire this data. Also, the terminal stations 20c and 20d have failed to acquire data in the subsequent relay transmission time slot 612.

  Accordingly, the terminal station 20c cannot perform relay transmission in the next time slot 613. Therefore, the terminal station 20c directs the directivity of the receiving beam antenna 1008 in the direction of the control station 10 and shifts to the reception state. Thereby, the terminal station 20c acquires data from the control station 10 using a beam antenna.

  In terminal station 20d, relay transmission is not performed by terminal station 20c in time slot 613. Therefore, in the time slot 613, the directivity of reception beam antenna 1008 is directed toward control station 10 and transitions to a reception state. To do. Thereby, similarly to the terminal station 20c mentioned above, data is acquired from the control station 10 using a beam antenna. Therefore, data transmission can be performed without omission to all the terminal stations in the frame.

  As described above, according to the second embodiment, when relay transmission cannot be confirmed, the terminal station directs the directivity of the receiving beam antenna toward the control station. At this time, since the relay station cannot confirm the relay transmission, the control station 10 retransmits data using the omni-pattern transmission antenna. Thereby, since the time slot can be used effectively as in the first embodiment, highly reliable data communication can be realized.

  The above is an example of a typical embodiment of the present invention, but the present invention is not limited to the embodiment described above and shown in the drawings, and can be appropriately modified and implemented without departing from the scope of the present invention. .

  In addition, you may comprise so that the process in the control station 10 mentioned above and the terminal station 20 may be implemented with the program installed in the computer incorporated in these apparatuses. This program can be provided not only by a communication means such as a network but also by storing it in a recording medium such as a CD-ROM.

Claims (14)

It has a control station and a plurality of terminal stations that transmit data for each frame, a transmission right is assigned to each time slot in the frame, and a terminal station having the transmission right relays and transmits data from the control station A communication system,
The control station
Transmitting means for transmitting data to the plurality of terminal stations for each frame;
Confirming means for confirming the state of relay transmission by a terminal station having a transmission right for each time slot;
A communication system comprising: a retransmission unit that retransmits data during a time slot in which the state of the relay transmission is confirmed according to a result of confirmation by the confirmation unit. The control station
A first antenna having directivity at a predetermined angle;
A second antenna having directivity at a wider angle than the first antenna,
The transmission means includes
Transmitting data to the plurality of terminal stations using the second antenna;
The retransmission means includes
2. The communication system according to claim 1, wherein data is retransmitted using the first antenna to a terminal station having a transmission right in a time slot in which the state of the relay transmission is confirmed. The transmission means and the retransmission means are:
The communication system according to claim 1, wherein data is transmitted and retransmitted to the plurality of terminal stations. The control station
A first antenna having directivity at a predetermined angle;
A second antenna having directivity at a wider angle than the first antenna,
The confirmation means includes
Whether relaying transmission was performed by the terminal station having the transmission right by directing the directivity of the first antenna toward the terminal station having the transmission right for a predetermined detection period every time the time slot starts. Check whether or not
The transmission means includes
The communication system according to claim 1, wherein data is transmitted to the plurality of terminal stations using the second antenna. Each of the plurality of terminal stations
A first terminal side antenna having directivity at a predetermined angle;
A second terminal station side antenna having directivity at a wider angle than the first terminal station side antenna;
Control means for directing the directivity of the first terminal station side antenna in the direction of the control station when a time slot in which the local station has a transmission right starts in a state where data from the control station cannot be normally received The communication system according to any one of claims 1 to 4, further comprising: The control means includes
6. The communication according to claim 5, wherein directivity of the first terminal station side antenna is directed toward the control station during a time slot in which relay transmission is not performed by the terminal station having the transmission right. system. It has a control station and a plurality of terminal stations that transmit data for each frame, a transmission right is assigned to each time slot in the frame, and a terminal station having the transmission right relays and transmits data from the control station A communication method for a communication system, comprising:
The control station
Transmitting data to the plurality of terminal stations for each frame;
Confirm the status of relay transmission by the terminal station having the transmission right for each time slot,
A communication method of a communication system, wherein data is retransmitted during a time slot in which the state of relay transmission is confirmed according to the confirmation result. It has a control station and a plurality of terminal stations that transmit data for each frame, a transmission right is assigned to each time slot in the frame, and a terminal station having the transmission right relays and transmits data from the control station A control station in a communication system,
Transmitting means for transmitting data to the plurality of terminal stations for each frame;
Confirming means for confirming the state of relay transmission by a terminal station having a transmission right for each time slot;
A control station comprising: retransmission means for retransmitting data during a time slot in which the state of relay transmission is confirmed according to a result of confirmation by the confirmation means. A first antenna having directivity at a predetermined angle;
A second antenna having directivity at a wider angle than the first antenna,
The transmission means includes
Transmitting data to the plurality of terminal stations using the second antenna;
The retransmission means includes
9. The control station according to claim 8, wherein data is retransmitted using the first antenna to a terminal station having a transmission right in a time slot in which the state of relay transmission is confirmed. The transmission means and the retransmission means are:
The control station according to claim 8, wherein data is transmitted and retransmitted to the plurality of terminal stations. A first antenna having directivity at a predetermined angle;
A second antenna having directivity at a wider angle than the first antenna,
The confirmation means includes
Whether relaying transmission was performed by the terminal station having the transmission right by directing the directivity of the first antenna toward the terminal station having the transmission right for a predetermined detection period every time the time slot starts. Check whether or not
The transmission means includes
The control station according to claim 8, wherein data is transmitted to the plurality of terminal stations using the second antenna. A first terminal station side antenna having directivity at a predetermined angle, and a second terminal station side antenna having directivity at a wider angle than the first terminal station side antenna, received from the control station A terminal station that relays data to other terminal stations,
Receiving means for receiving data from the control station;
Relay means for relaying data received by the receiving means using the second terminal station side antenna;
Control means for directing the directivity of the first terminal station side antenna in the direction of the control station when a time slot in which the local station has a transmission right starts in a state where data from the control station cannot be normally received And a terminal station. It has a control station and a plurality of terminal stations that transmit data for each frame, a transmission right is assigned to each time slot in the frame, and a terminal station having the transmission right relays and transmits data from the control station A computer built in the control station in the communication system,
Transmitting means for transmitting data to the plurality of terminal stations for each frame;
Confirming means for confirming the status of relay transmission by a terminal station having a transmission right for each time slot;
A program for functioning as retransmission means for retransmitting data during a time slot in which the state of relay transmission is confirmed according to a result of confirmation by the confirmation means. A first terminal station side antenna having directivity at a predetermined angle, and a second terminal station side antenna having directivity at a wider angle than the first terminal station side antenna, received from the control station A computer built in a terminal station that relays data to other terminal stations,
Receiving means for receiving data from the control station;
Relay means for relaying data received by the receiving means using the second terminal station side antenna;
Control means for directing the directivity of the first terminal station side antenna in the direction of the control station when a time slot in which the local station has a transmission right starts in a state where data from the control station cannot be normally received Program to function as.

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