JP4525540B2 - One-to-many wireless communication system and method - Google Patents

Description

  The present invention relates to a point-to-multipoint (P-MP) configured by one base station and a plurality of subscriber stations, that is, a one-to-multiple wireless communication system, and more particularly, as an access method, TDMA (Time Division Multiple Access). : Time division multiple access).

  A one-to-many FWA (Fixed Wireless Access) system is a wireless communication system in which one fixed base station communicates with a plurality of fixed base stations. Among them, in TDMA / TDD (Time Division Duplex) that uses a common radio frequency in the transmission and reception directions, it is possible to construct a flexible and efficient system by controlling the assigned time slots. (For example, refer nonpatent literature 1.).

  FIG. 2 is a diagram showing a radio frame configuration in the one-to-multiple radio communication system using the TDMA / TDD system described in Non-Patent Document 1. The frame period is fixed, for example, 1 ms. As shown in FIG. 2A, the radio frame has a downlink region, an uplink region, and a GT (Guard Time) region. The downlink area is an area transmitted by the base station, the uplink area is an area transmitted by any of the subscriber stations, and GT prevents signal interference when switching from uplink to downlink. It is an area.

  The downlink region further includes a downlink header region and a downlink data region. The downlink header area reports frame structure information, monitoring control information, slot demand allocation designation that notifies a subscriber station that can use the slot demand area, and notifies the subscriber station of the slot position of the uplink data area to be used. Each piece of information for specifying uplink data allocation.

  The downlink data area is composed of a plurality of slots (N in FIG. 2B) as shown in FIG. 2B, and each slot is information for identifying a subscriber station that is the destination of the slot. It has a certain subscriber station number, data for the destination subscriber station, an error detection code, and a preamble (PR) that precedes them.

  The uplink region has a DMF (Delay Measurement Frame) region, a slot demand region, and an uplink data region. The DMF area is an area for adjusting the transmission timing of the signal transmitted from each subscriber station to avoid collision of signals from each subscriber station. The slot demand area is the area where the subscriber station When signal transmission is desired, this is an area used for notifying the base station to that effect, and only a subscriber station designated by slot demand allocation designation in the downlink header area can be used.

  The uplink data area is composed of a plurality of slots (M in FIG. 2 (c)) as shown in FIG. 2 (c), and each slot is information for identifying the subscriber station that is the transmission source of the slot. A subscriber station number, data to the base station, an error detection code, a preamble preceding them, and a GT for preventing collision between adjacent slots.

  FIG. 6 is a diagram showing assignment of subscriber station numbers in a conventional system. According to FIG. 6, 8 bits are assigned to the subscriber station number, and 1 to 239 can be used as the subscriber station number among 0 to 255 that can be expressed by 8 bits, and 0 and 240 to 255 are not yet used. It is in use.

Yasui, Mizumoto, Kuwahara, “Wireless IP Access System Signal Processing Technology”, NTT R & D November 2002, pp. 76-85

  For example, when it is desired to transmit the same signal to a plurality of subscriber stations or all the subscriber stations, the base station generates a slot including the subscriber station number of the subscriber station for each subscriber station of the destination, It is necessary to store and transmit in the downlink data area. That is, the base station needs to reserve a slot in the downlink data area for all the destination subscriber stations and transmit the same data to each subscriber station. For this reason, there is a problem in that the radio band cannot be effectively used, and the processing capability at the base station is reduced and the delay is increased.

  Accordingly, the present invention provides a one-to-many wireless communication system that efficiently transmits the same signal to a plurality of subscriber stations and / or all subscriber stations, that is, performs efficient multicast and / or broadcast communication and It aims to provide a method.

  It is another object of the present invention to provide a one-to-multiple wireless communication system and method that do not cause a decrease in processing capacity and an increase in delay in base stations when performing multicast and broadcast communications.

According to the wireless communication system of the present invention,
A wireless communication system comprising a base station and a plurality of subscriber stations, wherein the base station has a one-to-one correspondence between destination information of data received from the network and subscriber station numbers When data is received from the network, the received data is transmitted in a wireless signal in association with the subscriber station number corresponding to the destination information of the data, and the subscriber station has its own subscriber station number and The subscriber station number unique to the multicast group to which the local station belongs, and among the radio signals transmitted by the base station, the subscriber station number unique to the local station and the subscriber station number unique to the multicast group to which the local station belongs It is characterized by receiving associated data.

According to another embodiment of the wireless communication system of the present invention,
When the base station transmits data received from the network to some of the subscriber stations belonging to the multicast group, the base station transmits the received data in association with the subscriber station number unique to the multicast group, and the multicast group A subscriber station that can receive or cannot receive the received data is transmitted with a subscriber station number unique to the subscriber station, and the subscriber station It is also preferable to receive the data associated with the subscriber station number unique to the multicast group to which the own station belongs only when it is designated as receivable or not designated by the distribution instruction.

According to another embodiment of the wireless communication system of the present invention,
The base station holds an encryption key corresponding to the subscriber station number and transmits the received data after encrypting it with the encryption key corresponding to the associated subscriber station number. It is also preferable to hold an encryption key corresponding to the subscriber station number having and to decrypt the received encrypted data with the encryption key corresponding to the associated subscriber station number.

According to the base station in the present invention,
When there is a one-to-one correspondence between the destination information of the data received from the network and the subscriber station number, and the data is received from the network, the received data is converted into the subscriber station corresponding to the destination information of the data. A base station that transmits a radio signal in association with a number, wherein the correspondence relationship is such that a single subscriber station number is associated with destination information indicating a plurality of subscriber stations. To do.

According to the wireless communication method of the present invention,
And a base station, a communication method in a radio communication system constituted by a plurality of subscriber stations, each subscriber station and the multicast group has its own subscriber station ID, the base station from the network When there is a one-to-one correspondence between the destination information of the received data and the subscriber station number, and data is received from the network, the received data is changed to the subscriber station number corresponding to the destination information of the data. The subscriber station is associated with the subscriber station number unique to the own station and the subscriber station number unique to the multicast group to which the station belongs, out of the radio signals transmitted by the base station. It is characterized by receiving data.

  The base station has a correspondence relationship between the destination information of the data received from the network and the subscriber station number. However, since the multicast station is assigned a subscriber station number unique to the multicast group, the base station If the data addressed to the multicast group is transmitted in association with the subscriber station number unique to the multicast group, the subscriber station belonging to the multicast group and having the subscriber station number unique to the multicast group receives the data. This eliminates the need to individually transmit data to the subscriber stations constituting the multicast group.

  The best mode for carrying out the present invention will be described in detail below with reference to the drawings.

  FIG. 1 is a system configuration diagram of a one-to-multiple wireless communication system according to the present invention. According to FIG. 1, the base station 1 has set up a radio line with a plurality of subscriber stations 2. Base station 1 is connected to network 3, and subscriber station 2 is connected to a communication terminal (not shown) such as a personal computer. A communication terminal (not shown) connected to the subscriber station 2 can communicate with each communication device on the network 3 by the wireless communication system configured by the subscriber station 2 and the base station 1.

  At the interface point between the network 3 and the base station 1, for example, a VID (VLAN ID) compliant with IEEE802.1Q is used, and the base station uses the correspondence between the stored VID and the subscriber station 2, The subscriber station 2 that is the destination of the layer 2 frame with the VLAN tag to be received is recognized.

  FIG. 2 is a configuration diagram of a radio frame used between the base station 1 and the subscriber station 2 in the system according to the present invention. The radio frame configuration itself is as described in the prior art, and the description is omitted.

  FIG. 3 is a block diagram of the base station 1 according to the present invention. According to FIG. 3, the base station 1 includes a communication control unit 10, a high frequency unit 11, and an antenna 12. The high frequency unit 11 amplifies a radio frequency signal received by the antenna 12 with a low noise amplifier, converts the frequency to an intermediate frequency and outputs the signal to the communication control unit 10, and the intermediate frequency from the communication control unit 10 After the signal is converted into a radio frequency, the transmitter 112 that amplifies the power and outputs the signal, and the switch 113 that switches the connection destination of the antenna 12 to the receiver 111 or the transmitter 112 are provided.

  The communication control unit 10 includes a modem unit 101, a TDMA control unit 102, a reception buffer unit 103, a transmission buffer unit 104, a communication interface unit 105, a packet number measurement unit 106, a slot allocation unit 107, a multicast protocol. And a corresponding unit 108. The reception buffer unit 103 and the transmission buffer unit 104 have a buffer for each subscriber station number.

  The communication interface unit 105 is an interface part with the network 3 such as an IP network, and includes tag information included in a frame received from the network, for example, a VID value of a layer 2 frame conforming to IEEE 802.1Q, and a subscriber station number. Is maintained. The correspondence relationship between the subscriber station number and the frame tag information is set in advance from the maintenance management system.

  FIG. 5 is a diagram showing the correspondence between subscriber station numbers and tag information used in the present invention. In FIG. 5, any one of VID values # 1 to # 999 is associated with subscriber station numbers 1 to 239, and these values are used for unicast communication. Further, the subscriber station number 240 and the VID value # 1000 are associated with the subscriber station number 245 and the VID value # 1001, and these values are used for multicast communication. Further, the subscriber station number 246 is associated with the VID value # 1006, and these values are used for broadcast communication.

  The communication interface unit 105 accumulates data to be transmitted to the subscriber station 2 among the frames received from the network 3 in a buffer of the subscriber station number corresponding to the tag information of the received frame in the transmission buffer unit 104. . Further, the data stored in the buffer of the reception buffer 103 is read, and a frame to the network 3 having tag information corresponding to the subscriber station number of the read buffer is generated and transmitted to the network 3.

  The packet number measurement unit 106 measures the number of packets stored from the data amount stored in the buffer corresponding to each subscriber station number in the transmission buffer unit 104 and notifies the slot allocation unit 107 of the number of packets. Here, one packet is the amount of data that can be transmitted in one slot of the downlink data area of the radio frame shown in FIG. That is, the packet number measurement unit 106 converts the amount of data stored in each buffer into the number of radio frame slots and notifies the slot allocation unit 107 of the data amount.

  The slot allocation unit 107 obtains data to be transmitted in the next radio frame by a predetermined method based on the number of packets stored in each buffer notified by the packet number measurement unit 106. The buffer in the transmission buffer unit 104 Is notified to the TDMA control unit 102. That is, the subscriber station number of the buffer for data transmission is determined and notified to the TDMA control unit 102 by a slot allocation instruction. Further, based on the uplink allocation request from each subscriber station 2 received via the TDMA control unit 102, the allocation of the slot of the uplink data area that the subscriber station 2 uses for radio frame transmission is determined, and the allocated slot To the subscriber station 2 via the TDMA control unit 102. As a slot allocation method, there are a round robin method in which allocation is performed fairly among subscriber stations, an allocation method in which a minimum bandwidth is guaranteed for each subscriber station, and the like.

  Based on the subscriber station number specified by the slot allocation instruction from slot allocation section 107, TDMA control section 102 reads an amount of data corresponding to the slot in the downlink data area from the corresponding buffer of transmission buffer section 104. Subsequently, the read data and its subscriber station number are stored in the downlink data area of the radio frame shown in FIG. 2, and a signal to be transmitted to the subscriber station is generated. Further, the signal received from the modem unit 101 is terminated, and the data of each slot in the uplink data area is stored in the buffer of the corresponding subscriber station number provided in the reception buffer 103.

  The modem unit 101 modulates the radio frame generated by the TDMA control unit 102 and outputs the modulated radio frame to the high frequency unit 11, demodulates the signal from the high frequency unit 11, and outputs the demodulated signal to the TDMA control unit 102. The function of the multicast protocol corresponding unit 108 will be described later.

  FIG. 4 is a block diagram of the subscriber station 2 according to the present invention. According to FIG. 4, the subscriber station 2 includes a communication control unit 20, a high frequency unit 21, and an antenna 22. The high frequency unit 21 amplifies a radio frequency signal received by the antenna 22 with a low noise amplifier, converts the frequency to an intermediate frequency, and outputs the signal to the communication control unit 20, and the intermediate frequency from the communication control unit 20 After the signal is converted into a radio frequency, the transmitter 212 that amplifies the power and outputs it, and the switch 213 that switches the connection destination of the antenna 22 to the receiver 211 or the transmitter 212 are provided.

  The communication control unit 20 includes a modem unit 201, a TDMA control unit 202, a reception buffer unit 203, a transmission buffer unit 204, a communication interface unit 205, a packet number measurement unit 206, and a control unit 209.

  The control unit 209 notifies the TDMA control unit 201 of a subscriber station number to be received from a subscriber station number set in advance from the outside and a subscriber station number specified by a delivery instruction from a base station described later. .

  The modem unit 201 demodulates the signal from the high frequency unit 21 and outputs the demodulated signal to the TDMA control unit 202, modulates the radio frame generated by the TDMA control unit 202, and outputs the modulated radio frame to the high frequency unit 21.

  The TDMA control unit 202 terminates the signal received from the modem unit 101, and among the slots in the downlink data area, only the data in the slot that matches the subscriber station number to be received notified from the control unit 209, The data is stored in a buffer corresponding to the subscriber station number provided in the reception buffer 203. Also, a signal to be transmitted to the base station 1 is generated by reading an amount of data corresponding to the slot of the uplink data area from the corresponding buffer of the transmission buffer unit 204. In addition, like the subscriber station number 246 in FIG. 5, the subscriber station number assigned to the broadcast is held as a subscriber station number to be received by all subscriber stations.

  The communication interface unit 205 is an interface part with a communication terminal such as a personal computer, reads out data stored in the buffer of the reception buffer 203, generates a frame to be transmitted to the communication terminal, and transmits the frame. Further, the frame received from the communication terminal is stored in the buffer of the transmission buffer unit 204.

  The packet number measuring unit 206 measures the number of packets stored in the buffer in the transmission buffer unit 204 and notifies the base station 1 of a slot allocation request for the uplink data area via the TDMA control unit 202.

  As described above, a subscriber station number is also assigned to multicast or broadcast, and each subscriber station 2 has its own subscriber station number and a multicast group to which the subscriber station 2 belongs. The subscriber station number assigned to and the subscriber station number assigned to broadcast are set in advance.

  The base station 1 has a subscriber station number unique to each subscriber station 2, a subscriber station number assigned to each multicast group, a subscriber station number assigned to broadcast, and data received from the network 3. For example, when the destination information such as tag information is recognized and the destination information indicated by the data received from the network 3 is a specific subscriber station 2, the subscriber station 2 has its own subscriber station. If it is a multicast group using the number, the subscriber station number assigned to the multicast group is used. If the broadcast is broadcast, the received data is sent using the subscriber station number assigned to the broadcast. Each subscriber station 2 receives only the slot of the subscriber station number set in its own station.

  Thereby, multicast and broadcast can be realized by the same processing as unicast communication. Therefore, it does not cause problems such as a decrease in processing capability and an increase in delay in the base station as in the prior art, and furthermore, the number of downlink data area slots equal to the number of subscriber stations belonging to the multicast group is used. It is not necessary to transmit the same data separately, and effective use of the radio band can be achieved.

  Next, the multicast protocol corresponding unit 108 of the base station 1 will be described. In the configuration described above, it is possible to transmit data collectively to subscriber stations belonging to a certain multicast group by using the subscriber station number assigned to the multicast group. There is a case where it is desired to permit reception only to a part of subscriber stations belonging to the multicast group and to disallow reception to the remaining part. Therefore, a multicast protocol corresponding unit 108 is provided in the base station 1.

  The communication interface unit 105 indicates that the subscriber station corresponding to the destination information of data received from the network 3 indicates a subset of a multicast group, for example, 9 stations out of a multicast group composed of 10 stations. As described above, the subscriber station number assigned to the multicast group is transmitted as a radio signal, and the multicast protocol corresponding unit 108 is notified of this.

  The multicast protocol corresponding unit 108 indicates to each subscriber station 2 via the TDMA control unit 102 a subscriber station that can receive the data associated with the subscriber station number indicating the multicast, or cannot receive the data. A distribution instruction signal indicating the subscriber station is transmitted. A subscriber station that can receive or cannot receive is designated by a subscriber station number unique to the subscriber station.

  The control unit 209 of each subscriber station 2 indicates, for example, a subscriber station that can receive a distribution instruction, and if the local station is indicated by the distribution instruction, the control instruction is indicated to the TDMA control unit 202 by the distribution instruction. When the multicast subscriber station number is notified and the local station is not indicated by the distribution instruction, the multicast subscriber station number indicated by the distribution instruction is not notified to the TDMA control unit 202. As a result, transmission can be performed only to some of the subscriber stations belonging to the multicast group.

  Further, a different encryption key is assigned to each subscriber station number, and the base station 1 holds encryption keys corresponding to all subscriber station numbers used, and stores data in each slot in the downlink data area. , Encrypted with an encryption key corresponding to the destination subscriber station number and transmitted, and the subscriber station 2 holds the encryption key corresponding to the subscriber station number to be received by itself, and receives the received data as the destination It is possible to realize highly confidential communication by decrypting and receiving with the encryption key corresponding to the subscriber station number indicated as, and encrypting the upstream direction in the same manner.

  As described above, the base station 1 has been described using the case of receiving the VLAN-tagged layer 2 frame from the network 3, but the present invention is not limited to the above example. That is, if the data received from the network 3 is addressed to a specific subscriber station 2, the subscriber station 2 is designated as a multicast group if it is multicast, and to the base station if it is broadcast. If 1 can be recognized from data or a frame received from the network 3, the present invention can be applied.

1 is a system configuration diagram of a one-to-multiple wireless communication system according to the present invention. 1 is a diagram showing a radio frame configuration of a one-to-multiple radio communication system. FIG. 4 is a block diagram of a base station according to the present invention. FIG. 3 is a block diagram of a subscriber station according to the present invention. It is a figure which shows the example of a setting of a subscriber station number and the tag information of a flame | frame. It is a figure which shows allocation of a subscriber station number in the conventional system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base station 2 Subscriber station 3 Network 10, 20 Communication control part 11, 21 High frequency part 12, 22 Antenna 101, 201 Modem part 102, 202 TDMA control part 103, 203 Reception buffer part 104, 204 Transmission buffer part 105, 205 Communication interface unit 106, 206 Frame number measurement unit 107 Slot allocation unit 108 Multicast protocol support unit 111, 211 Receiver 112, 212 Transmitter 113, 213 Switch 209 Control unit

Claims (5)

A wireless communication system comprising a base station and a plurality of subscriber stations,
The base station has a one-to-one correspondence between destination information of data received from the network and a subscriber station number. When data is received from the network, the received data corresponds to the destination information of the data. In association with the subscriber station number to be transmitted by radio signal,
The subscriber station has its own subscriber station number and its own multicast group subscriber station number, and among the radio signals transmitted by the base station, its own subscriber station number And receiving data associated with a subscriber station number unique to the multicast group to which the own station belongs. When the base station transmits data received from the network to some of the subscriber stations belonging to the multicast group,
The received data is transmitted in association with a subscriber station number unique to the multicast group, and among the subscriber stations belonging to the multicast group, a subscriber station that can receive or cannot receive the received data. , Send a distribution instruction signal specified by the subscriber station number unique to the subscriber station,
The subscriber station receives data associated with the subscriber station number unique to the multicast group to which the own station belongs only when it is designated as receivable or not designated by the distribution instruction. The system according to claim 1. The base station holds an encryption key corresponding to the subscriber station number, transmits the received data after encrypting with the encryption key corresponding to the associated subscriber station number,
The subscriber station holds an encryption key corresponding to the subscriber station number of the local station, and decrypts the received encrypted data with the encryption key corresponding to the associated subscriber station number. The system according to claim 1 or 2. When there is a one-to-one correspondence between the destination information of the data received from the network and the subscriber station number, and the data is received from the network, the received data is converted into the subscriber station corresponding to the destination information of the data. A base station that transmits a radio signal in association with a number,
The base station is characterized in that the correspondence relationship is such that one subscriber station number is associated with destination information indicating a plurality of subscriber stations. A communication method in a wireless communication system comprising a base station and a plurality of subscriber stations,
Each subscriber station and each multicast group has its own subscriber station number,
The base station has a one-to-one correspondence between destination information of data received from the network and a subscriber station number. When data is received from the network, the received data corresponds to the destination information of the data. In association with the subscriber station number to be transmitted by radio signal,
The subscriber station receives data associated with a subscriber station number unique to the own station and a subscriber station number unique to the multicast group to which the station belongs, out of radio signals transmitted by the base station. Method.

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