JP2010135897A - Base station apparatus, wireless communication system, wireless communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system and the like for performing communication in a space multiplex system without the system breakdown even when there is a relay station of a fewer number of relays in the wireless communication system. <P>SOLUTION: In a base station which has a plurality of antennas and relays a relay station by using a space multiplex system to communicate with a terminal, the number of space multiplexes of the relay station is managed, communication channels are allocated on the basis of the number of multiplexing terminals, and wireless communication is performed with the terminal on the basis of the allocated communication channels. In doing so, when the number of space multiplexes the relay station supports is smaller than the number of multiplexing terminals, communication channels of the number of space multiplexes are allocated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base station or the like that has a plurality of antennas and communicates with one or a plurality of terminals by relaying a relay station using a spatial multiplexing scheme.

  Conventionally, various wireless communication systems that use radio between a base station and a terminal are known. For example, in the case of a mobile phone, a system is configured in which data is transmitted and received between a base station installed at a high position and a terminal (mobile station). As a simple configuration, for example, there is a method in which one base station has a radius of 1000 m as a service area (service area) and the base station communicates with a terminal (mobile station) in the service area.

However, the radio is straight, and it is difficult to reach the shielded place, and the inside of the building or the underground shopping street is out of service. For this reason, the method of extending communication distance by using a relay station (relay station) is taken (for example, refer patent document 1).
JP 2008-118659 A

  Here, as an example of a relay station, a configuration of a repeater often used as a relay station will be described with reference to FIG. First, a signal received by the receiving antenna 900 is amplified by the amplifier 902 and then converted into an IF signal by the frequency converter 904. The converted IF signal is extracted only in a necessary band by the SAW filter 906. The extracted signal is frequency converted by the variable amplifier 908 and the frequency converter 910. The frequency-converted signal is amplified by the amplifier 912 and then transmitted by the transmitting antenna 914.

  For example, when a wireless communication system is constructed in an underground shopping center, the receiving antenna 900, the amplifier 902, and the frequency converter 904 are installed on the ground, and the rest are installed in the underground shopping center using cables. By installing the transmitting antenna 914 on the ceiling of the underground shopping street, radio waves can reach even in the underground shopping street, and communication between the terminal and the base station becomes possible.

  In FIG. 21, only one system is shown for convenience of explanation, but it is a matter of course that a normal mobile phone has a system in the reverse direction because of bidirectional communication. That is, a receiving antenna is installed on the underground shopping street side to receive radio waves from the mobile terminal. And a radio wave is transmitted / received with respect to a base station from the antenna for transmission installed on the ground. In this way, bidirectional communication between the base station and the terminal becomes possible.

  In recent years, there has been known a communication system that constructs a communication path using a plurality of transmission channels in order to increase the transmission speed. For example, in wireless communication systems, techniques such as MIMO (Multi Input Multi Output) have been proposed.

  The MIMO technique is a technique for transmitting and receiving data using a plurality of antennas, performing signal spatial multiplexing using a difference in propagation path characteristics, and separating the signals. Here, FIG. 22 shows an outline of a communication model.

  In FIG. 22, communication is performed using four transmission antennas and four reception antennas. In general, if the antenna of a radio channel is different, the situation of the radio space is different, and the channel characteristics are also different for each antenna. Therefore, it is possible to separate signals using the difference in propagation characteristics, and it is possible to perform multiplexed communication by the number of transmission / reception antennas. For example, with 4 × 4 MIMO, transmission of up to four times is possible for each antenna.

  The operation of the base station for realizing the MIMO will be described with reference to FIG. FIG. 23 is a diagram for explaining an example of the configuration of the base station 950.

  The base station 950 includes a base station control device 110 and a wireless communication unit 960. The wireless communication unit 960 includes a data buffer 130 and a data buffer 146, a transmission modem unit 132, an RF unit 134 and an RF unit 142, a reception modem unit 144, a wireless control unit 150, and a terminal management unit 152. It is prepared for. In addition, a transmission antenna 136 is connected to the RF unit 134 of the wireless communication unit 120, and a reception antenna 140 is connected to the RF unit 142.

  The base station control device 110 includes each terminal management device that grasps the status of a plurality of terminal stations connected to the base station, and manages the performance and the like of the terminals. This is because the connected terminals are not one type of performance category, and the number of multiplexes that can be processed by MIMO, the modulation class to be supported, the frequency band, etc. may be different for each terminal, so they are managed. .

  When performing communication with the terminal, the wireless control unit 150 controls the wireless communication method that can be communicated according to the individual information, the propagation path state such as reception sensitivity, the amount of data to be transmitted / received, the data quality to be maintained, etc. The terminal communicates with the terminal via the transmission modem unit 132 and the reception modem unit 144 in accordance with the terminal that actually communicates.

  Specifically, data to be transmitted to the terminal from the upper layer base station control apparatus 110 is once stored in the data buffer 130. Then, the signal is output from the transmission antenna 136 via the transmission modem unit 132 and the RF unit 134.

  The data received by the receiving antenna 140 is demodulated into data via the RF unit 142 and the receiving modem unit 144 and stored in the data buffer 146. Then, the data is output from the data buffer 146 to the base station controller 110 which is an upper layer.

  Here, the wireless control unit 150 controls the operation of the wireless communication unit 960. In addition, the number of MIMO spatial multiplexing is determined in accordance with the number of terminals that can be processed by MIMO, and packets to be transmitted and received are configured. An example of the packet configuration configured as described above is shown in FIG.

  In this figure, the base station 950 communicates with five terminals A, B, C, D, and E. There is a packet header at the head, and then there is a communication area from terminal A to terminals B, C, D, and E. In this figure, there are three repetitions, which is one packet. In addition, terminals A to E in the figure have “terminal A processable multiplex number of 4”, “terminal B processable multiplex number of 1”, “terminal C processable multiplex number of 4”, “terminal D of terminal D” Description will be made assuming that the number of multiplexes that can be processed is 4 ”and“ the number of multiplexes that can be processed by terminal E is 2 ”. Information regarding these terminals is managed by the terminal management unit 152.

And
Terminal A has a processable multiplex number of 4, but uses 2 multiplexes because the propagation path condition is not good.
Terminal B uses 1 multiplex because the number of multiplexes that can be processed is 1.
Terminal C uses 4 multiplexes because the number of multiplexes that can be processed is 4 and the propagation path condition is good.
Terminal D uses 4 multiplexes because the number of multiplexes that can be processed is 4 and the propagation path condition is good.
-Since the number of multiplexes that can be processed is 2, terminal E uses 2 multiplexes.
And is controlled.

  FIG. 25 shows an outline of the wireless communication system 9 when there is such a MIMO transmission and a relay station.

  Here, the number enclosed in “<>” under the terminal name in FIG. 25 is the number of multiplexes that can be processed in the terminal. Specifically, the processable multiplex number of terminal A is “4”, the processable multiplex number of terminal B is “1”, the processable multiplex number of terminal C is “4”, and the processable multiplex number of terminal D is “4”. 4 ”, the number of multiplexes that can be processed by the terminal E is“ 2 ”.

  In addition, terminal A and terminal B are directly connected to the base station, terminal C is connected to base station 10 via relay station A, and terminals D and E are connected to base station 10 via relay station B.

  FIG. 25 shows an example in which such a MIMO multiplexed signal is passed through a relay station composed of two systems. In MIMO, a multiplexed signal can be demodulated using the difference in propagation characteristics of space. In 4 × 4, 16 independent propagation paths (16 arrows in FIG. 22) are configured. However, since the relay station has only two antennas, only 8 channels of 4 × 2 can be configured.

  For this reason, even if four antennas are prepared on the terminal side, the independence is lost in the middle of propagation, so that there is a problem that MIMO signals cannot be separated.

  That is, among the packet data shown in FIG. 26, the spatial multiplexing numbers 1 and 2 can be demodulated without any problem through the relay station, but the spatial multiplexing numbers 3 and 4 are separated when the relay station is used. There was a problem that it was impossible.

  In the figure, terminals C and D perform 4-multiplex MIMO communication when not via a relay, but cannot perform 4-multiplex communication because they are via a relay.

  Conventionally, in such a case, when the terminals C and D return a NAK signal indicating that the signal is not properly transmitted, the base station performs retransmission, and further, even if several retransmissions cannot be transmitted, The process of lowering the number of spatial multiplexing is performed, and the process is performed until an ACK signal indicating that it has been transmitted correctly is received. This is a problem because the traffic due to the retransmission process is very large and the transmission delay is also large.

  Accordingly, in view of the above-described problems, the present invention aims to provide a base station and the like that can perform accurate spatial multiplexing communication even when there are relay stations with a small number of relays in a wireless communication system. is there.

  In view of the above-described problems, a base station of the present invention has a plurality of antennas, and relays the relay station using a spatial multiplexing scheme to communicate with one or a plurality of terminals via the relay station. A relay station connection management unit that manages information on terminals that communicate with each other and information on the spatial multiplexing number supported by the relay station, and determines the multiplexing number that communicates based on the information managed by the relay station management unit And a data transmission / reception unit that multiplexes with the terminal and transmits / receives data based on the multiplexing number determined by the multiplexing number determination unit.

  In the base station of the present invention, the multiplexing number determination unit determines the spatial multiplexing number supported by the relay station managed by the relay station connection management unit as an upper limit of the number of multiplexing to communicate. To do.

  The base station of the present invention further includes a terminal management unit that manages the number of multiplexes that can be processed by the terminal, and the multiplex number determination unit is a spatial multiplexing supported by the relay station managed by the relay station connection management unit. The smaller value of the number and the number of multiplexes that can be processed by the terminal managed by the terminal management unit is determined as the multiplex number for communication.

  In addition, the base station of the present invention further includes a propagation path characteristic determination unit that determines a possible multiplex number based on the propagation path characteristic, and the multiplex number determination unit is a relay managed by the relay station connection management unit Of the spatial multiplexing number supported by the station and the possible multiplexing number determined by the propagation path characteristic determination unit, the smaller value is determined as the multiplexing number for communication.

  In the base station of the present invention, the multiplexing number determination unit may determine the multiplexing number when the relay station connection management unit manages that the terminal that transmits and receives the data does not pass through the relay station. The upper limit is the number of multiplexes that can be processed by the terminal.

  Further, in the base station apparatus of the present invention, the multiplexing number determining unit, when the terminal is connected via a plurality of relay stations, is the smallest of the spatial multiplexing numbers supported by the plurality of relay stations. The spatial multiplexing number is determined as the multiplexing number for communication.

  Further, in the base station of the present invention, the data transmission / reception unit is the smallest among the terminals included in the packet when data transmission / reception is performed by packet multiplexing data of a plurality of terminals performing communication. Based on the number of multiplexing, data is multiplexed and transmitted / received.

  In the base station of the present invention, the data transmission / reception unit performs time division when data transmission / reception is performed by multiplexing data of a plurality of terminals performing communication by combining frequency division multiplexing and time division multiplexing. Data transmission / reception is performed by frequency division multiplexing based on the smallest multiplexing number among terminals included in multiple time slots.

  The base station apparatus of the present invention further includes an in-cell relay station determination unit that forms a plurality of cells and determines whether or not a relay station is arranged in the cell, and the multiplexing number determination unit includes: When a relay station is arranged by the intra-cell relay station determination unit, it is determined that the smallest one among the spatial multiplexing numbers supported by the arranged relay station is a communication multiplexing number, and the data transmission / reception is performed. When transmitting / receiving data to / from a terminal included in the cell, the unit multiplexes and transmits / receives data based on the multiplexing number determined by the multiplexing number determination unit.

  Further, in the base station apparatus of the present invention, the relay station management unit further divides and manages a group of terminals that communicate via the relay station and a group of terminals that communicate without passing through the relay station. The multiplex number determination unit sets a spatial multiplex number supported by the relay station as an upper limit of the multiplex number for a terminal of the group that communicates via the relay station, and performs communication without passing through the relay station. The terminal of the group to be used is characterized in that the multiplex number that can be processed by the terminal is set as the upper limit of the multiplex number for communication.

  The wireless communication system of the present invention includes a base station, one or a plurality of terminals, and a relay station that relays between the base station and the terminals, and performs wireless communication using a spatial multiplexing scheme with a plurality of antennas The base station includes a relay station connection management unit that manages information on terminals that communicate via the relay station, and information on a spatial multiplexing number supported by the relay station, and the relay station management unit. Based on managed information, a multiplex number determination unit that determines the number of multiplexes to communicate, and data transmission / reception that multiplexes with the terminal and transmits / receives data based on the multiplex number determined by the multiplex number determination unit And a section.

  In the wireless communication system of the present invention, the multiplexing number determination unit determines the spatial multiplexing number supported by the relay station managed by the relay station connection management unit as an upper limit of the multiplexing number to communicate. And

  Further, in the wireless communication system of the present invention, the multiplexing number determination unit, when the terminal is connected via a plurality of relay stations, is the smallest of the spatial multiplexing numbers supported by the plurality of relay stations. The spatial multiplexing number is determined as the multiplexing number for communication.

  In the wireless communication system of the present invention, the terminal is configured to determine whether the terminal is communicating with the base station via the relay station, and the relay by the relay station determination unit. A notification means for notifying the base station of a result of determination as to whether or not communication is performed via a station, wherein the relay station management unit communicates with the terminal via the relay station. It is characterized by managing whether or not it is being performed as terminal information by the notification means.

  In the wireless communication system of the present invention, the relay station determination unit further determines a spatial multiplexing number supported by the relay station, and the notification means determines whether or not communication is performed via the relay station. Along with the determination result, the base station is notified of the number of spatial multiplexing supported by the relay station.

  In the radio communication system according to the present invention, the notifying unit notifies the determination result as adaptive modulation information including MIMO.

  In the radio communication system of the present invention, the relay station determination unit determines whether or not the relay station is routed by measuring a delay time of a signal received by the terminal.

  The wireless communication system of the present invention is characterized in that at least one of the plurality of relay stations is connected to the base station by wire.

  The wireless communication method of the present invention includes a base station, one or a plurality of terminals, and a relay station that relays between the base station and the terminals, and performs wireless communication using a spatial multiplexing scheme using a plurality of antennas. A wireless communication method for use in a system, comprising: a relay station connection management step for managing information on a terminal that communicates via a relay station; and information on a spatial multiplexing number supported by the relay station; and Multiplex determination step for determining the number of multiplexes to be communicated based on managed information, and data transmission / reception step for multiplexing and transmitting with the terminal based on the multiplex number determined by the multiplex number determination step It is characterized by having.

  The program of the present invention has a plurality of antennas, relays a relay station using a spatial multiplexing scheme, communicates with one or a plurality of terminals, information on terminals communicating via the relay station, A relay station connection management function for managing information on the spatial multiplexing number supported by the relay station, a multiplexing number determination function for determining a multiplexing number based on the information managed by the relay station management function, and A data transmission / reception function for performing data transmission / reception by multiplexing with the terminal is realized based on the multiplexing number determined by the multiplexing number determination function.

  As described above, according to the present invention, in a base station that has a plurality of antennas and relays a relay station using a spatial multiplexing scheme to communicate with one or a plurality of terminals, communication is performed via the relay station. Information on the terminal to be transmitted and information on the spatial multiplexing number supported by the relay station, and based on the managed information, determine the multiplexing number to communicate, and based on the determined multiplexing number, the terminal And data transmission / reception is performed. Therefore, the multiplex number is determined based on the information on the communicating terminal and the information on the spatial multiplexing number supported by the relay station, and data is transmitted / received with the determined multiplexing number, whereby the terminal and the base Even if a relay station with a small number of supported spatial multiplexing is installed between the stations, it will be possible to send and receive signals that can be spatially separated from each terminal with the correct multiplexing number, and this will cause problems due to the installation of the relay station. Can be eliminated, and good communication can be performed.

  The best embodiment in a wireless communication system when the present invention is applied will be described with reference to the drawings.

[1. First Embodiment]
First, the first embodiment will be described. As the first embodiment, an example will be described in which MIMO is used as a communication method.

[1.1 Overview of wireless communication system]
First, an outline of a wireless communication system 1 to which the present invention is applied is shown in FIG. As shown in the figure, the wireless communication system 1 includes a base station 10, relay stations 20 (relay stations A and B), and terminals 30 (terminals A to E).

  Here, the numbers enclosed in “<>” in FIG. 1 are the spatial multiplexing number in the relay station 20 and the processable multiplexing number in the terminal 30. Specifically, the relay station is A “2 × 2 relay station”, and the relay station B is “4 × 4 relay station”. Also, the processable multiplex number of terminal A is “4”, the processable multiplex number of terminal B is “1”, the processable multiplex number of terminal C is “4”, the processable multiplex number of terminal D is “4”, The number of multiplexes that can be processed by terminal E is “2”.

  Terminal A and terminal B are directly connected to base station 10, terminal C is connected to base station 10 via relay station A, and terminals D and E are connected to base station 10 via relay station B.

[1.2 Device configuration]
Subsequently, each device configuration will be described. The relay station 20 has the same configuration as that of the conventional relay station described with reference to FIG.

[1.2.1 Base station configuration]
The configuration of the base station 10 will be described with reference to FIG. The base station 10 includes a base station control device 110 and a radio communication unit 120 as shown in the figure. The wireless communication unit 120 includes a data buffer 130 and a data buffer 146, a transmission modem unit 132, an RF unit 134 and an RF unit 142, a reception modem unit 144, a wireless control unit 150, a terminal management unit 152, And a relay station connection management unit 154. In addition, a transmission antenna 136 is connected to the RF unit 134 of the wireless communication unit 120, and a reception antenna 140 is connected to the RF unit 142. In addition, the same code | symbol is attached | subjected to the component same as the base station 950 demonstrated in FIG. 23, and the detailed description is abbreviate | omitted.

  Here, the base station 10 in this figure is different from the base station 950 described in FIG. 23 in that the relay station connection management unit 154 is arranged. The relay station connection management unit 154 is a functional unit that manages the relay stations of each terminal together with the terminals managed by the terminal management unit 152.

  The terminal management unit 152 stores and manages each terminal and the number of multiplexes that can be processed by the terminal. FIG. 3A shows an example of a terminal table managed by the terminal management unit 152. Here, the processable multiplex number of terminal A is “4”, the processable multiplex number of terminal B is “1”, the processable multiplex number of terminal C is “4”, and the processable multiplex number of terminal D is “4”. The number of multiplexes that can be processed by terminal E is managed as “2”.

  Further, the number of used multiplexes used for actual communication is stored in association with each terminal. For example, although the processable multiplex number is “4” for terminal A, the multiplex number actually used is “2” because the propagation path condition is not good.

  In the relay station connection management unit 154, information on whether the terminal 30 is via the relay station 20 or the number of relay stations supported is managed. Assuming communication with 5 terminals, terminals A and B are connected directly to the base station, terminal C is connected to relay station A with 2 × 2 support, and terminals D and E are connected to relay station B with 4 × 4 support. Managed information is managed.

  Here, as shown in FIG. 3, the relay station connection management unit 154 stores and manages the relay station to be relayed and the supported multiplexing number of the relay station for each terminal. Here, since the terminals A and B are directly connected to the base station 10, information regarding the relay station is not stored. The terminal C relays the relay station A, and it is managed that the supported multiplexing number of the relay station is “2”. The terminals D and E relay the relay station B, and it is managed that the supported multiplexing number of the relay station is “4”.

  In general, the number of supported multiplexes corresponds to the number of antennas and the number of relays in the relay station. In other words, in a relay station with a support number of 2 × 2, repeaters are connected to two input antennas, and two output antennas are connected.

  Further, whether or not the terminal 30 is via the relay station 20 can be grasped by receiving a notification from the terminal 30. Specifically, a relay station determination unit 352 of the terminal 30 described later determines whether the terminal 30 is communicating with the base station 10 via the relay station 20. The base station 10 can grasp the determination result by notifying the base station 10.

  In accordance with conventional control, radio control section 150 uses the information in relay station connection management section 154 to determine the spatial multiplexing number of MIMO to communicate with each terminal. For example, even if the terminal C has the ability to receive 4 × 4 MIMO, since the relay station A is a relay station that supports 2 × 2, the maximum spatial multiplexing number of transmission is controlled to “2”. .

  In other words, the upper limit when not passing through a relay station is the lower limit of [the number of multiplexes that can be processed by a terminal, the number of multiplexes limited by propagation path characteristics], and the upper limit when passing through a relay station is [the number of multiplexes that can be processed by a terminal] The upper limit is the one with the smallest number of multiplexes limited by propagation path characteristics, the number of multiplexes supported by the relay station].

FIG. 4 shows the state of the packet at that time. The packet is restricted by “the number of multiplexes that can be processed by the terminal”, “the restriction by the propagation path”, and “the multiplex number supported by the relay station”. In the present embodiment, the transmission signal is as follows.
Terminal A: The number of multiplexes that can be processed is 4, the restriction by the propagation path is 2 multiplexes, and the relay station is not used. Therefore, 2 multiplexing is used because the propagation path condition is not good.
Terminal B: The number of multiplexes that can be processed is 1, the restriction by the propagation path is 1 multiplex, and the relay station is not used. Therefore, one multiplex is used.
Terminal C: The number of multiplexes that can be processed is four, the restriction by the propagation path is four multiplexes, and 2 × 2 relay stations are used. Therefore, the condition of the propagation path is good, but 2 multiplexes are used due to relay station restrictions. Terminal D: The number of multiplexes that can be processed is 4, the restriction by the propagation path is 4 multiplexes, and 4 × 4 relay stations are used. Therefore, 4 multiplex is used as it is because the propagation path condition is good.
Terminal E: The number of multiplexes that can be processed is 2, 2 multiplexes due to propagation paths are used, and 4 × 4 relay stations are used. Therefore, even if the propagation path condition is good, 2 multiplexes are used depending on the number of multiplexes that can be processed.

[1.1.2 Terminal configuration]
Next, the configuration of the terminal 30 will be described with reference to FIG. According to this figure, the terminal 30 includes a terminal controller / upper layer 310 and a wireless communication unit 320. The wireless communication unit 320 includes a data buffer 330 and a data buffer 346, a transmission modem unit 332, an RF unit 334 and an RF unit 342, a reception modem unit 344, a wireless control unit 350, a relay station determination unit 352, It is configured with. In addition, a transmitting antenna 336 is connected to the RF unit 334, and a receiving antenna 340 is connected to the RF unit 342.

  Here, in the terminal 30 of this figure, the reception RF unit 342 has four reception systems, and can receive a 4 × 4 spatially multiplexed signal. On the other hand, the transmission system also has four RF units and can communicate up to 4 × 4 spatial multiplexing.

  Therefore, the terminal shown in the figure notifies the base station 10 of the terminal capability as the reception system 4 and the transmission system 4.

  The relay station determination unit 352 is a functional unit that determines whether or not communication with the base station is performed via the relay station. The determination result is notified to the base station 10.

  Moreover, although the capability of a terminal does not change normally, whether it is via a relay station changes timely. Therefore, it is necessary to transmit this information more frequently than the terminal capability information. For example, the received power information and the propagation path information (CQI) are positioned in the same position as the information transmitted to the base station 10 depending on the propagation path. Can be transmitted.

  Also, depending on the system, if MIMO information that can be received after judging the propagation path condition is transmitted as adaptive control information, it can be used. In this case, it is possible to cope without increasing the number of extra information bits.

  Also, since the number of multiplexes that can be processed by the terminal and the number of multiplexes supported by the relay station are limited to the smaller one, it is also possible to convey as the number of receivable capabilities via a relay without sending both. Can be substituted.

[1.2 Control example]
Subsequently, an example of control in the present embodiment will be described using a flowchart.

[1.2.1 First control example]
First, a first control example will be described using the flowchart of FIG. First, the base station 10 determines a terminal that is a target of a wireless packet, that is, a terminal that communicates (step S10).

  Subsequently, the terminal performance information determined in step S10 is read from the terminal management unit 152 (step S12). Then, the wireless communication line status (for example, propagation path characteristics based on the reception level such as SINR) is determined (step S14).

  Subsequently, processing is performed for each terminal. Next, it is determined from the information of the relay station connection management unit 154 whether the terminal 30 is communicating via the relay station 20 (step S16). Here, when the terminal 30 does not pass through the relay station 20 (step S16; No), the processing capacity number of the terminal is set as the multiplexing number for communication (step S20).

  On the other hand, when the terminal is communicating via the relay station (step S16; Yes), the number of relay stations supported by the terminal and the number of terminals that can be multiplexed are determined from the information in the relay station connection management unit 154. The numbers are compared (step S18).

  If the supported multiplexing number of the relay station through which the relay station passes is larger than the spatial multiplexing number of the terminal (step S18; Yes), the processing capacity number of the terminal is set as the multiplexing number to be communicated (step S20). If the supported multiplexing number of the relay station is less than or equal to the multiplexable number of the terminal (step S18; No), the relay station supporting multiplexing number is set as the communication multiplexing number (step S22).

  Then, for all the terminals, it is determined whether or not the set number of multiplexes for communication has been completed (step S24). If there is a terminal that has not yet set the multiplex number for communication (step S24; No), the next terminal is set (step S28), and the process is repeated from step S16. In this way, the radio control unit 150 sets the number of multiplexed communications for each terminal.

  As described above, when the multiplex number to be communicated for all the terminals is set (step S24; Yes), a transmission signal is generated by the transmission modem unit 132 according to the parameters of the terminal to be transmitted, and is transmitted via the RF unit 134. Then, transmission is performed from the transmission antenna 136 (step S26).

  In this way, by preparing the relay station connection management unit 154 and holding information related to the relay station, the base station 10 to the terminal 30 via the relay station 20 [terminal processing multiplex number, It is possible to transmit at a multiplexing number that considers all of the multiplexing numbers limited by the propagation path characteristics and the relay station support multiplexing number]. As a result, for example, although communication is via a 2 × 2 relay station, it is determined by only the capability of the terminal and is transmitted with a 4 × 4 spatial multiplexing number. The conventional problem that the propagation delay becomes large can be solved.

  That is, according to the present embodiment, even when a terminal via a relay station and a terminal not via are mixed, spatial multiplexing corresponding to each can be performed.

  Here, the downlink, that is, the packet configuration from the base station 10 to the terminal 30 has been described as an example. However, even in the uplink, the same configuration can be used and control taking into account the limitation on the number of multiplexes that can be performed by the relay station 20 can be performed. In addition, in the terminal 30 and the relay station 20, there are cases where the number of spatial multiplexing in transmission / reception is asymmetric (for example, when there are four reception antennas and two transmission antennas), in which case control is performed accordingly. be able to.

  Further, in this embodiment, for the sake of explanation, the same number of MIMO configurations have been described for the transmitting and receiving antennas. However, since there are four base station antennas, 4 × 2 spatial multiplexing number is utilized by utilizing transmission diversity. Of course, it is possible to apply to the second MIMO. If the number of multiplexing is less than or equal to the number of relay stations that can be multiplexed, the present invention can be realized without any problems even if the number of transmission antennas of the base station increases.

[1.2.2 Second control example]
Next, a second control example will be described with reference to FIG. Here, the same processes as those in the first control example of FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Here, in the first control example, it is determined whether the number of supported relay stations exceeds the number of spatial multiplexing of the terminal for each terminal. However, in the wireless control in the second control example, the terminal via the relay station is determined. Sets the smallest multiplexing number of the support multiplex among the relay stations as the support multiplex number via the relay station, and determines the radio system for communication with the terminal.

  First, the base station 10 determines a terminal that is a target of a wireless packet, that is, a terminal that performs communication (step S10). Subsequently, the terminal performance information determined in step S10 is read from the terminal management unit 152 (step S12). Then, the wireless communication line status (for example, propagation path characteristics based on the reception level such as SINR) is determined (step S14).

  Next, it is determined from the information in the relay station connection management unit 154 whether there is a terminal connected via a relay station among the terminals (step S40).

  If there is a terminal that passes through the relay station, the minimum supported multiplex number of the relay station is compared with the processable multiplex number of the terminal (step S42). Here, when the minimum supported multiplex number of the relay station is equal to or less than the processable multiplex number of the terminal (step S42; No), the minimum supported multiplex number of the relay station is set as the multiplex number to be communicated (step S44).

  That is, in the first control example, it is assumed that it is clear which relay station each terminal has which performance, but in an actual underground parking lot, a plurality of relay stations connected to the ground are mixed. It can be assumed that there are cases. When the terminal is moving, there are cases where relay stations with different numbers of supported 2 × 2 or 4 × 4 are mixed, and radio waves passing through either relay station may be received or strength may be switched.

  Therefore, in the second control example, the minimum of all the relay stations that may be routed to all target terminals so that there is no problem even if the terminal 30 connected to the base station 10 is routed through any relay station 20. And the number of multiplexed communication is set.

  That is, when 2 × 2 and 4 × 4 supported relay stations are mixed, the upper limit of five terminals connected to the base station 10 is 2 × 2.

[1.2.3 Third control example]
Next, a third control example will be described with reference to FIG. Here, the same processes as those in the first control example of FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The third control example is a control example in which, if a relay station is installed in a service area of a base station, that is, in a cell, the upper limit of the number of multiplexed communications of the base station is the support number of the relay station.

  In the second control example, if there is a packet-configured terminal via the relay station, the upper limit is set. However, in a more open environment, a terminal that has nothing to do with the relay station is considered to be via the relay station. There is a case.

  This is prominent when a relay station is placed in an open space as shown in FIG. 9. Which of the base station and the relay station communicates depends on the environment at that time, and it is not possible to control it in real time. This is not only complicated, but also difficult in practice. For example, it is prominent when it is installed in a suburb as shown in FIG. 9A, or when it is installed to eliminate a dead zone by a building as shown in FIG. 9B.

  Specifically, in step S50, it is determined whether or not the relay station is in the cell (in the service area of the base station). Here, when the relay station is in the cell (step S50; Yes), the support space multiplexing number of the relay station is compared with the multiplexable number of the base station (step S52).

  Here, when the multiplexable number of base stations is smaller than the supported spatial multiplex number of relay stations (step S52; No), the multiplexable number of base stations is limited to the spatial multiplex number of relay stations.

  As described above, in this control example, for one cell, the upper limit of the spatial multiplexing number is limited to the relay station with the smallest number of multiplexing, which is a bottleneck, so that no matter which route is used for communication, The base station does not send a multiplex number exceeding the supported multiplex number, and the conventional problem that data cannot be separated and cannot be demodulated can be solved. That is, if there is a relay station that supports only 2 × 2 in the cell, the upper limit of the number of multiplexed communication of all terminals is limited to 2 × 2.

[2. Second Embodiment]
Next, the second embodiment will be described. In the first embodiment, the wireless communication system has been described based on TDMA multiplexed in a time division manner as shown in FIG. 4, but as a second embodiment, a case where OFDMA communication is used will be described.

  OFDMA communication is a communication method in which users are multiplexed by finely dividing blocks on the time and frequency axes, and signals for a plurality of terminals are multiplexed in one packet.

[2.1 Explanation of operation]
This will be specifically described with reference to FIG. In the first embodiment, terminal allocation is performed for each time slot in the TDMA-based example, whereas in the second embodiment, a plurality of terminals are set in the same time slot and are divided by time and frequency. This is an example in which terminals are allocated in block units. FIG. 10A is a diagram schematically showing the state of each channel in OFDMA. In this figure, the entire band is divided into seven frequency channels, and a maximum of seven independent signals can be carried.

  In OFDMA, since the subcarriers constituting each channel are independent, when a plurality of users use each channel, even if the same time slot is used, transmission is performed with different multiplexing numbers for each user. Is possible.

  FIG. 10B is a diagram schematically showing a state in which the frequency f is plotted on the horizontal axis and the time t is plotted on the vertical axis, and packets addressed to each terminal are multiplexed in this OFDMA. Each packet is distributed in each time slot (1) to (7).

  Here, for example, the terminals C and D arranged in the (4) slot and (5) slot are terminals via the relay station, and the terminals C and D have a 4 × 4 multiplexing capability. Shall.

[2.2 Control example]
Subsequently, a control example in the present embodiment will be described.

[2.2.1 Fourth control example]
As a control example in the second embodiment, a fourth control example will be described. In the fourth control example, the control shown in the flowchart of FIG. 11 is performed.

  First, a terminal to be a wireless packet target is determined (step S60), and terminal performance information is read from the terminal management unit 152 (step S62). Then, the transmission path characteristic is determined from SINR or the like (step S64).

  Subsequently, it is determined from the information of the relay station connection management unit 154 whether or not the relay station connection is made (step S66). That is, in the first control example of the first embodiment, the determination is made for each terminal, whereas in the fourth control example, it is determined whether there is a terminal via a relay station for each time slot.

  Then, when there is a terminal via the relay station (step S66; Yes), the supported multiplexing number of the relay station via is compared with the processable multiplexing number of the terminal (step S70). Here, when the supported multiplex number of the relay station to be routed is larger than the multiplexable number of the terminal (step S70; Yes), the processing capacity number of the terminal is set as the multiplex number for communication (step S68). On the other hand, when the supported multiplex number of the relay station to be passed is equal to or less than the multiplexable number of the terminal (step S70; No), the spatial multiplex number of the relay station is set as the multiplex number for communication (step S66).

  Subsequently, it is determined whether or not all time slots have been completed (step S74). Here, if all the time slots are not completed, the process is executed for the next time slot (step S74; No-> step S78-> step S66).

  As described above, when the allocation of terminals and the number of multiplexed communication are set for the frequency axis and time axis slots of OFDMA, the transmission modem unit 132 generates a transmission signal according to the parameters, and the RF unit Transmission is performed from the transmission antenna 136 via 134.

  By controlling in this way, the communication multiplex number of time slots (4) and (5) depends on [the multiplex number that can be processed by the terminal, the multiplex number limited by the propagation path characteristics, the multiplex number supported by the relay station]. Determined. That is, the signals destined for terminals A, B, and E that are simultaneously transmitted by frequency division in the same time slot are up to the number of multiplexing that the relay station supports.

  As an OFDMA reception technique, even when terminals C and D communicating as frequency division are demodulated, all frequency bands (all channels of ch1 to ch7) are subjected to FFT processing, and other cases may be necessary. This is because the signal for the terminal is also used for the reception process.

  In this case, considering that the signals of the terminals A, B, and E are demodulated for the demodulation processing of the terminals C and D, if the signals for these terminals exceed the relay support multiplexing number, the signals are demodulated. Can not be.

  Therefore, as in this embodiment, by controlling the number of communication multiplexes for terminals included in all bands in the same time slot, it becomes possible to demodulate signals for terminals included in the same time slot. Therefore, communication can be performed appropriately through the relay station.

[2.2.2 Fifth control example]
Next, a fifth control example will be described with reference to FIG. In FIG. 10, only the time slots (4) and (5) via the relay station determine the maximum number of packets by the relay station multiplexing limit. In this example, the preceding (3) is also limited. It is characterized by adding.

  When processing the base station signal and the relay station signal, the signal of (3) overlaps with (4) due to delay, resulting in ISI (intersymbol interference). Therefore, in order to accurately demodulate (4), it is necessary to remove such overlapping signals, and for this purpose, it is necessary to demodulate the signal (3). However, if the number of multiplexed signals exceeding the spatial multiplexing number of the relay station is contained in the time slot of (3), processing cannot be performed.

  Therefore, also in this case (3), the upper limit number that can be multiplexed is set so as not to exceed the spatial multiplexing number. Accordingly, even when the signal of (3) is demodulated in order to remove the signal of (3) from (4), it can be appropriately decoded.

[2.2.3 Sixth control example]
Subsequently, a sixth control example will be described with reference to FIG. In the sixth control example, the maximum number of multiplexed packets is determined on a packet-by-packet basis due to the multiplexing restriction of the relay station.

  In OFDMA, error correction or the like may be processed in batches in units of packets exceeding the units of time slots. In the terminal A of FIG. 13, a plurality of blocks are allocated in a time-frequency-frequency axis within a packet, and some of these data are error correction units. That is, for error correction processing, it is necessary to demodulate all the signals of terminal A scattered in the packet.

  In this case, it is necessary to set all signals in the packet to the multiplexing number supported by the relay station.

  In this control example, the first packet has a terminal via a relay station that supports only the multiplexable number up to 2 × 2, and therefore the upper limit is set to 2 × 2.

  In this case, the same control can be performed even with a packet that is only time-multiplexed without being multiplexed with frequency and time as in OFDMA.

  Another control example will be described. Depending on the system, blocks such as error correction may straddle the packet. In this case, in order to perform error correction decoding, it is necessary to collectively process signals extending over a plurality of time slots and packets, and if there is a signal exceeding the multiplex limit of the relay station, it cannot be demodulated.

  An example of this is shown in FIG. In this example, the case where the minimum unit of signal processing, for example, error correction is composed of two packets is shown. The first packet includes terminals C and D via relay, and the upper limit is 2 × 2 as in FIG. The second packet originally does not include the terminals C and D. However, since the signal processing unit is composed of two packets, a high multiplexing number is not set for the second packet, and the upper limit is 2 × 2. Limit to.

Thus, by applying the present invention, signal separation can be made possible even when signal processing is performed across a plurality of packets.
Therefore, it is not limited in fixed units such as time slots and packets, but in the demodulation processing unit of these terminals, the number of multiplexing is limited to the relay station.

[3. Third Embodiment]
Next, a third embodiment will be described. In the third embodiment, a case where terminals that do not pass through a relay station and terminals that pass through a relay station are grouped to perform communication will be described. In this case, any communication method may be used as a communication method. However, in this embodiment, description will be made assuming that OFDMA communication is used.

  The configurations of the base station, mobile station, and the like are the same as those in the first embodiment, and thus description thereof is omitted.

[3.1 Seventh Control Example]
As a control example in this embodiment, a seventh control example will be described with reference to FIG. Up to the previous example, the number of multiplexes was limited when a packet was assigned to a terminal and then passed through a relay station. However, in this control example, whether the packet is routed via a relay station or not. By sorting the terminals and grouping the terminals, it becomes possible to efficiently distribute the terminals.

  In the case of OFDMA communication, the relay station and other than the relay station are divided into two groups, and the time slots are divided for each group.

  In this control example, only a maximum of 2 multiplexes can be performed via the relay station. Therefore, by collecting only terminals that do not pass through the relay station, a maximum of 2 multiplex settings are made in group 1, and group 2 can freely respond to terminal performance and reception sensitivity. Multiple multiplex numbers can be set.

  Until the second embodiment, it was not distinguished whether the terminal was assigned via a relay or not, and as a result of the assignment, if there was at least one relay, spatial multiplexing of all the time slots was performed. The number was limited. Therefore, even if the number of terminals via the relay is limited, there is a risk that the number of multiplexed packets is set low.

  In contrast, in the present embodiment, by grouping in advance, the entire packet is not suppressed by the influence of the terminal via the relay, and the throughput of the entire packet can be increased.

  The above-described control is necessary when the relay station has a support number smaller than the maximum number of multiplexed base stations.

  Another feature is that the necessary group 1 of relay stations is brought to the head of the packet. As described above, in the demodulation via the relay station, it is effective to place a group via the relay station from the head of the packet in order to avoid a multiplexing number exceeding the multiplexing capability of the relay station at the previous time timing.

  In addition to grouping by time slot, it is also possible to sort by packet, and it can be divided into group 1 packet and group 2 packet. Also in this case, since the packet for group 2 can be transmitted with the optimum multiplexing number without considering the limitation of the multiplexing number by the terminal via the relay, the overall throughput can be improved.

[3.2 Eighth Control Example]
Next, an eighth control example will be described with reference to FIG. In this control example, grouping is performed by using terminals that pass through the relay station and terminals that do not pass through the relay station as one axis, and the number of multiplexing supported by the terminal as an axis.

  In this grouping, grouping is performed in consideration of both the presence / absence of relay stations and the upper limit multiplexing number of terminals, so that grouping can be performed with a substantial upper limit multiplexing number, and multiplexing can be performed more efficiently than the seventh control example described above. You can assign a number.

  As described above, the third embodiment has been described using the OFDMA examples. However, in these examples, the point is that the terminals are allocated to a plurality of terminals on the time and frequency axes, and the frequencies are orthogonal. You don't have to. That is, it is needless to say that a configuration such as FDMA-TDMA may be used.

[4. Modified example]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

[4.1 First Modification]
First, as a first modification, in the above-described embodiment, the relay station determination unit is described as being provided in the terminal 30, but may be provided in the base station 10 and determined on the base station 10 side.

  The configuration of the base station at this time is shown in FIG. 2, a relay station determination unit 156 is installed to determine whether a signal from the terminal passes through the relay station. The relay station determination unit 156 is connected to the reception modem unit 144 and the relay station connection management unit 154.

  Here, means for realizing the relay station determination unit 156 will be described. A general configuration of a repeater, which is an example of a relay station, includes an amplifier, a filter, and a frequency conversion unit as shown in FIG. Therefore, a signal via the relay station that is transmitted and received by each terminal is delayed accordingly. The relay station determination unit 156 includes a relay station determination device that measures arrival time delay and determines whether or not the relay station 20 has passed, and uses this as management information. Since the base station 10 transmits and receives via the relay station, the delay is doubled.

  As another method, a method using a pilot signal will be described. Usually, pilot signals for MIMO are prepared for the transmission antennas. An example of MIMO for 4 × 4 is shown in FIG.

  FIG. 18 is an example of OFDM, for example, where the frequency frame on the horizontal axis represents each subcarrier, and the time frame on the vertical axis represents an OFDM symbol. In the case of MIMO, in order to grasp the propagation path characteristics from each transmission antenna, there is a method of transmitting from only one transmission antenna and measuring the propagation characteristics without interference.

  In this figure, four pilot signals are transmitted from only each antenna for each transmission antenna. The frequency subcarrier of P1 contains a signal transmitted only by the transmission antenna 1, and the transmission antennas 2, 3, and 4 do not transmit anything to this subcarrier. Each of P2, P3, and P4 only receives transmission signals from transmission antennas 2, 3, and 4, respectively.

  In reception, the signals are received by the receiving antennas 1, 2, 3, and 4. However, the four propagation paths can be known from the signals P1, P2, P3, and P4 received by the receiving antenna 1, and similarly, the receiving antennas 2, 3, and 4 are known. By knowing 4 propagation paths each in 4, a total of 16 propagation paths can be known, and MIMO separation becomes possible.

  These 16 propagation paths are signals that have passed through different paths, and the correlation is originally low. However, when a relay station that supports a small number of antennas is used, for example, in the case of 2 × 2, since there are only two transmission antennas in the relay station, there are only eight independent propagation paths, High signal. Therefore, by looking at the correlation of the pilot signals, it is possible to determine the independence of the path path, and it is possible to determine whether it is via a relay station and whether it is a relay station that supports several systems.

  Note that, as an example of the relay station determination unit 156, an example in which the determination is made based on the delay time or the correlation of the pilot is shown, but it is needless to say that the determination method via the relay station may be another method. It is comprised by the apparatus which can determine, and performing control based on it, and it is also possible to use another criterion. For example, in a relay station having a higher function than the repeater shown in the figure, the relay station itself can perform base station communication with the relay station class. Further, since the relay station itself is installed by the installer, it is possible to inform the base station in advance as the information about the performance supported by the base station.

[4.2 Second Modification]
Next, as a second modification, the wireless communication system of the present invention can be applied to multi-pop relaying. Here, multi-hop is to extend the distance by repeatedly using a relay station a plurality of times.

  Here, FIG. 19 shows an example of multi-hop relay. In the example of FIG. 19, the number of spatial multiplexing is 4 × 2, 2 × 3, 3 × 2, and 2 × 4 through three relay stations.

  In this case, it is not necessary to have information on all the relay stations, and the present invention can be applied by managing the information as the number of equivalent relay station supports with the minimum 2 × 2 as the number of supports.

[4.3 Third Modification]
Next, a case where the third modification is applied to an overhanging radio unit will be described with reference to FIG. The basic concept of the relay station itself is to fly to the relay station wirelessly and connect the terminal wirelessly to the relay station, but there is an overhanging radio unit that performs the same function.

  FIG. 20 shows an example of one wireless relay station and two wired wireless units. The overhang radio section is different from the relay station in that it is connected to the base station by wire, but it can be said to have exactly the same purpose in that it is installed in a place where the base station radio wave is difficult to reach to widen the communication area of the terminal.

  Also in this case, although the first part is different from wireless or wired, it is applicable to all the embodiments described above, and an equivalent effect can be obtained.

It is a figure for demonstrating the outline of the radio | wireless communications system in 1st Embodiment. It is a figure for demonstrating the structure of the base station in 1st Embodiment. It is a figure for demonstrating the relay station connection management part in 1st Embodiment. It is a figure for demonstrating the mode of the packet in 1st Embodiment. It is a figure for demonstrating the structure of the terminal in 1st Embodiment. It is a figure for demonstrating the operation | movement in the 1st control example. It is a figure for demonstrating the operation | movement in the 2nd control example. It is a figure for demonstrating the operation | movement in the 3rd control example. It is a figure for demonstrating the operation | movement in the 3rd control example. It is a figure for demonstrating the mode of the packet in 2nd Embodiment. It is a figure for demonstrating the operation | movement in the 4th control example. It is a figure for demonstrating the operation | movement in the 5th control example. It is a figure for demonstrating the operation | movement in the 6th control example. It is a figure for demonstrating the operation | movement in the 6th control example. It is a figure for demonstrating the operation | movement in the 7th control example. It is a figure for demonstrating the operation | movement in the 8th control example. It is a figure for demonstrating the operation | movement in a 1st modification. It is a figure for demonstrating the operation | movement in a 1st modification. It is a figure for demonstrating the operation | movement in a 2nd modification. It is a figure for demonstrating the operation | movement in a 3rd modification. It is a figure for demonstrating the structure of the relay station in the past. It is a figure for demonstrating a MIMO technique. It is a figure for demonstrating the structure of the base station for implement | achieving a MIMO technique. It is a figure for demonstrating the mode of the packet for implement | achieving a MIMO technique. It is a figure for demonstrating the outline of the radio | wireless communications system in a MIMO technique. In MIMO technology, it is a figure for demonstrating the outline of the system at the time of passing through a relay station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base station 110 Base station control apparatus 120 Radio | wireless communication part 130 Data buffer 132 Transmission modem part 134 RF part 136 Transmission antenna 140 Reception antenna 142 RF part 144 Reception modem part 146 Data buffer 150 Radio control part 152 Terminal management part 154 Relay station connection Management unit 156 Relay station determination unit 20 Relay station 30 Terminal 310 Terminal controller / upper layer 320 Wireless communication unit 330 Data buffer 332 Transmission modem unit 334 RF unit 336 Transmission antenna 340 Reception antenna 342 RF unit 344 Reception modem unit 346 Data buffer 350 Radio control unit 352 Relay station determination unit

Claims (20)

In a base station that has a plurality of antennas and communicates with one or a plurality of terminals by relaying a relay station using a spatial multiplexing scheme,
A relay station connection management unit that manages information on terminals that communicate via the relay station and information on the number of spatial multiplexing supported by the relay station;
Based on information managed by the relay station management unit, a multiplex number determination unit that determines the multiplex number to communicate,
Based on the multiplexing number determined by the multiplexing number determination unit, a data transmission / reception unit that multiplexes with the terminal and transmits / receives data;
A base station comprising:   2. The base station according to claim 1, wherein the multiplexing number determination unit determines the spatial multiplexing number supported by the relay station managed by the relay station connection management unit as an upper limit of the number of multiplexing to communicate. . A terminal management unit for managing the number of multiplexable terminals;
The multiplexing number determination unit is configured to select a smaller value of the spatial multiplexing number supported by the relay station managed by the relay station connection management unit and the processable multiplexing number of the terminal managed by the terminal management unit. The base station according to claim 2, wherein the base station is determined as a multiplexing number for communication. Further comprising a propagation path characteristic judging section for judging the number of possible multiplexing based on the propagation path characteristics;
The multiplexing number determination unit communicates the smaller value of the spatial multiplexing number supported by the relay station managed by the relay station connection management unit and the possible multiplexing number determined by the propagation path characteristic determination unit. The base station according to claim 2, wherein the base station is determined as a multiplexing number to be used.   When the relay station connection management unit manages that the terminal that transmits and receives the data does not go through a relay station, the multiplexing number determination unit sets the upper limit of the multiplexing number to the number of multiplexing that can be processed by the terminal. The base station according to claim 2, wherein   When the terminal is connected via a plurality of relay stations, the multiplexing number determination unit determines the smallest number of spatial multiplexing among the spatial multiplexing numbers supported by the plurality of relay stations as the number of multiplexed communication. The base station according to claim 2, wherein:   When the data transmission / reception unit performs data transmission / reception by packet-multiplexing data of a plurality of terminals performing communication, the data transmission / reception unit performs multiplexing based on the smallest multiplexing number among the terminals included in the packet. The base station according to any one of claims 1 to 6, wherein data is transmitted and received.   The data transmission / reception unit transmits and receives data by multiplexing data of a plurality of terminals performing communication by combining frequency division multiplexing and time division multiplexing. 7. The base station according to claim 1, wherein the base station performs data transmission / reception by frequency division multiplexing based on the smallest multiplexing number. The base station forms a plurality of cells;
Further comprising an in-cell relay station determination unit for determining whether a relay station is arranged in the cell;
When the relay station is arranged by the in-cell relay station judging unit, the multiplexing number judging unit communicates the smallest number among the spatial multiplexing numbers supported by the arranged relay station. And
The data transmission / reception unit, when transmitting / receiving data to / from a terminal included in the cell, multiplexes and transmits / receives data based on the multiplexing number determined by the multiplexing number determination unit. The base station according to claim 1. The relay station management unit manages a group of terminals that communicate via a relay station and a group of terminals that communicate without going through a relay station.
The multiplex number determination unit is a group that communicates via the relay station, the group communication without using the relay station, with the upper limit of the multiplex number communicating the spatial multiplex number supported by the relay station. The base station according to any one of claims 1 to 6, wherein the terminal of the base station sets the multiplex number that can be processed by the terminal as an upper limit of the multiplex number for communication. A wireless communication system including a base station, one or a plurality of terminals, and a relay station that relays between the base station and the terminal, and communicates using a spatial multiplexing scheme with a plurality of antennas,
The base station
A relay station connection management unit that manages information on terminals that communicate via the relay station and information on the number of spatial multiplexing supported by the relay station;
Based on information managed by the relay station management unit, a multiplex number determination unit that determines the multiplex number to communicate,
Based on the multiplexing number determined by the multiplexing number determination unit, a data transmission / reception unit that multiplexes with the terminal and transmits / receives data;
A wireless communication system comprising:   The wireless communication according to claim 10, wherein the multiplexing number determination unit determines the spatial multiplexing number supported by the relay station managed by the relay station connection management unit as an upper limit of the number of multiplexing to communicate. system.   When the terminal is connected via a plurality of relay stations, the multiplexing number determination unit determines the smallest number of spatial multiplexing among the spatial multiplexing numbers supported by the plurality of relay stations as the number of multiplexed communication. The wireless communication system according to claim 12, wherein: The terminal
A relay station determination unit that determines whether or not communication is performed via the base station and the relay station;
Notifying means for notifying the base station of the determination result as to whether or not communication is performed via the relay station by the relay station determining unit;
Have
14. The radio according to claim 12 or 13, wherein the relay station management unit manages whether or not the terminal is communicating via the relay station as terminal information by the notification means. Communications system. The relay station determination unit further determines the spatial multiplexing number supported by the relay station,
The notification means notifies the base station of a spatial multiplexing number supported by the relay station relay station together with a determination result of whether or not communication is performed via the relay station. Item 15. The wireless communication system according to Item 14.   The wireless communication system according to claim 14 or 15, wherein the notification unit notifies the determination result as adaptive modulation information including MIMO.   The wireless communication system according to claim 14, wherein the relay station determination unit determines whether or not the relay station is routed by measuring a delay time of a signal received by the terminal.   The wireless communication system according to claim 11, wherein at least one of the plurality of relay stations is connected to the base station by wire. A wireless communication method used in a wireless communication system that includes a base station, one or more terminals, and a relay station that relays between the base station and the terminals, and communicates using a spatial multiplexing scheme with a plurality of antennas. And
A relay station connection management step for managing information on terminals that communicate via the relay station and information on the number of spatial multiplexing supported by the relay station;
Based on the information managed in the relay station management step, a multiplex number determination step for determining the multiplex number for communication;
A data transmission / reception step for transmitting / receiving data multiplexed with the terminal based on the multiplexing number determined by the multiplexing number determination step;
A wireless communication method comprising: To a computer having a plurality of antennas and relaying a relay station using a spatial multiplexing method to communicate with one or a plurality of terminals,
A relay station connection management function for managing information of terminals communicating via a relay station and information on the number of spatial multiplexing supported by the relay station;
Based on the information managed by the relay station management function, a multiplex number determination function for determining the multiplex number to communicate,
Based on the multiplexing number determined by the multiplexing number determination function, a data transmission / reception function for multiplexing with the terminal and transmitting / receiving data;
A program to realize