JP4197349B2 - Communication apparatus and wireless communication system - Google Patents

Description

  The present invention relates to a communication apparatus that constitutes a multiple input multiple output (MIMO) system that simultaneously transmits two or more signals using a plurality of antennas, and in particular, a wireless communication system capable of realizing one-to-many simultaneous access and It relates to a communication method.

  Hereinafter, a conventional wireless communication system will be described. For example, when transmitting and receiving a broadband signal in a mobile environment, the communication device needs to overcome frequency selective fading. As one of techniques for dealing with this frequency selective fading, a multicarrier modulation / demodulation system, particularly OFDM (Orthogonal Frequency Division Multiplexing), is adopted in various wireless systems. On the other hand, in order to further increase the transmission capacity, a MIMO (Multiple Input Multiple Output) system that simultaneously transmits two or more signals using a plurality of antennas has attracted attention. This MIMO system is broadly divided into a system based on SDM (Space Division Multiplexing) and a system based on transmission diversity (STC: Space Time Coding). Here, as an example of the prior art, a wireless communication system employing the SDM system will be described. To do.

  In a general wireless communication system (see Non-Patent Document 1 below) that employs the SDM method, first, a transmission-side communication device divides a transmission signal into a plurality of information streams. Here, although error correction coding is performed for each stream, this processing may be applied to the transmission signal before division. Next, the communication apparatus on the transmission side performs predetermined modulation processing on each divided information stream, and further executes subcarrier mapping processing and IFFT processing to generate an OFDM time signal. Thereafter, the generated OFDM time signal is added with a guard interval, subjected to waveform shaping processing, up-converted by the RF unit, and transmitted from the transmission antenna.

  In the communication apparatus on the receiving side, the signal received by each receiving antenna is down-converted to generate a baseband signal, and further, a subcarrier signal is extracted by FFT processing. On the other hand, the communication device on the receiving side estimates a transmission path between the receiving antennas using a known signal included in the received signal. Then, the communication device on the receiving side combines the subcarrier signals between the antennas based on the transmission path estimation result, performs channel separation, and further performs predetermined demodulation processing and error on each separated information stream. A correction process is executed, and finally a received signal is output.

IEICE Technical Report RCS2001-135 "Proposal of SDM-COFDM System for Broadband Mobile Communications Realizing 100Mbit / s with MIMO Channel"

  However, the conventional wireless communication system (MIMO system) basically assumes one-to-one communication and does not consider one-to-many simultaneous access. Specifically, in an actual environment, it is considered that the number of antennas mounted on the mobile terminal (MT) is smaller than the number of antennas mounted on the access point (AP). It does not support one-to-many simultaneous access such as assigning the antenna of the AP to another MT and communicating simultaneously.

  The present invention has been made in view of the above, and in a MIMO system, a wireless communication system that assumes that a plurality of MTs simultaneously access an AP, a communication device that configures the wireless communication system, and a communication The purpose is to obtain a method.

  In order to solve the above-described problems and achieve the object, the present invention provides a first communication device (corresponding to AP11 in an embodiment described later) mounted with a plurality of antennas and a plurality of devices mounted with at least one antenna. Second communication devices (corresponding to MT1, MT2,...), And the first communication device and the second communication device mutually use an SDM (Space Division Multiplexing) channel corresponding to each antenna. In the wireless communication system that realizes the communication, the first communication device performs predetermined modulation processing, IFFT processing, guard interval (GI) on a plurality of signals to be transmitted to the second communication device. Generate a transmission signal by performing additional processing, and further generating a known signal for synchronization, and then inserting the known signal for synchronization at a predetermined position of the signal after adding the GI Stage (corresponding to modulation units 70 and 71, IFFT units 72 and 73, GI addition units 74 and 75, and synchronization signal generation unit 76), and antenna selection means for assigning transmission signals generated individually for each SDM channel to each antenna (Corresponding to the antenna selection unit 77), and the plurality of second communication devices analyze the transmission timing based on the individual known synchronization signals for each of the SDM channels included in the received signal. Analyzing means (corresponding to the transmission timing analyzing unit 34), and applying a predetermined modulation process, IFFT process, and GI addition process to a single signal or a plurality of signals to be transmitted to the first communication device, Based on channel configuration information notified from the first communication device (information indicating which SDM channel each second communication device uses to communicate) and the analysis result. Timing adjustment means (corresponding to the modulation units 36 and 37, IFFT units 38 and 39, GI addition units 40 and 41, and timing adjustment / preamble insertion unit 35) for adjusting the transmission timing of the transmission signal after the GI addition, The first communication device controls the transmission timing so that arrival time differences of received signals on all SDM channels transmitted from the plurality of second communication devices are within GI, and FFT It is characterized by performing processing.

  According to this invention, the first communication device performs use channel designation and transmission timing control for the plurality of second communication devices, and arrival time differences of signals on all the SDM channels fall within the GI. In this way, the time synchronization control is performed.

  According to the present invention, the first communication device can perform the FFT processing in a state in which the orthogonality of all signals received from the plurality of second communication devices is maintained. That is, the first communication device has an effect that simultaneous communication (one-to-many communication) with a plurality of second communication devices can be realized while maintaining the reception characteristics of the one-to-one communication in the prior art.

  Hereinafter, embodiments of a communication device, a wireless communication system, and a communication method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a wireless communication system according to the present invention. Here, as an example of a wireless communication system that realizes one-to-many simultaneous access, a communication apparatus (mobile terminal: MT) having two antennas with respect to a communication apparatus (access point: AP) having four antennas Suppose that they access at the same time. Specifically, the wireless communication system shown in FIG. 1 includes MT1 having antennas 3 and 4, MT2 having antennas 5 and 6, and AP11 having antennas 7, 8, 9, and 10, and MT1, 2 However, the information is simultaneously transmitted to the AP 11 using a 2-channel SDM (Space Division Multiplexing) channel, and the AP 11 receives the information with four antennas, and then separates and demodulates each channel.

  Here, an outline of the operation of the wireless communication system according to the present invention will be described. In the present invention, an OFDM (Orthogonal Frequency Division Multiplexing) -based multicarrier signal is assumed as a transmission / reception signal.

  In the conventional MIMO system, one-to-one communication is performed between the AP and the MT as described above, and communication using a plurality of antennas is performed between the devices. However, since the signals arriving at the AP do not necessarily have to be transmitted from the same MT, in the present embodiment, the AP 11 transmits signals transmitted from a plurality of MTs (corresponding to 1 and 2). Separate channels. That is, in the present invention, the SDM method is adopted as a communication method in the MIMO system, and a plurality of MTs communicate with the AP 11 at the same time. Then, the reception-side AT 11 collectively develops signals from each MT (each MT has a plurality of SDM channels) in the frequency domain, and performs channel separation on each subcarrier.

  FIG. 2 is a diagram showing a configuration when, for example, two stations MT1 and MT2 are communicating with the AP 11 at the same time. Here, signals A and B are simultaneously transmitted from the two antennas 3 and 4 of MT1, and signals C and D are simultaneously transmitted from the two antennas 5 and 6 of MT2. At this time, the arrival times of the signals A, B, C, and D differ depending on the positional relationship between the transmission stations MT1 and MT2 and the reception station AP11. That is, as shown in FIG. 3, when the arrival time difference of each signal falls within the guard interval (GI), the FFT processing can be performed while maintaining the orthogonality of all the signals. As shown, when the arrival time difference exceeds GI, it is impossible to set the FFT window so as to maintain the orthogonality of all signals. Therefore, in the present invention, when the AT 11 receives signals of a plurality of channels from the MTs 1 and 2 by one FFT, time synchronization control (transmission timing control) is performed so that the arrival time difference of each signal is within the GI.

  3 and 4 show a case where the signal is a single wave, a delayed wave is generated by reflection of a building or the like in an actual transmission line, so that the delayed wave is also taken into consideration in the GI. It is necessary to control the transmission timing so that the arrival time difference is reduced.

  Next, the configuration and operation of the MT1, 2 and AT11 will be described in detail. FIG. 5 is a diagram showing the configuration of MTs 1 and 2 according to the first embodiment. Transmission / reception antennas 21 and 22, conversion processing from high frequency signals to baseband signals S 21 and S 22, and high frequency signals from baseband signals S 39 and S 40 RF / IF units 23 and 24 that perform conversion processing, guard interval (GI) removal units 25 and 26 that remove guard intervals and set positions of FFT windows, and time signals S23 and S24 after GI removal are frequency FFT units 27 and 28 for converting signals S25 and S26, a channel estimation unit 29 for estimating the channel gain of each channel and each subcarrier, and channel separation from the channel gain S27 as a channel estimation result An equalization matrix generation unit 30 that generates an equalization matrix S28, a signal separation unit 31 that performs channel separation, and each channel after channel separation Demodulation units 32 and 33 that demodulate the signals S29 and S30, a transmission timing analysis unit 34 that determines transmission timing using information from the AP 11, and transmission timing adjustment processing based on transmission timing information S31 and channel configuration information S32 , And a timing adjustment / preamble insertion unit 35 that performs processing for adding a known pattern for the used SDM channel to the time signals S37 and S38 after GI addition, and modulation units 36 and 37 that perform predetermined modulation processing on the transmission signal, The IFFT units 38 and 39 for converting the modulation signals S33 and S34 on the subcarriers into the time signals S35 and S36, and the GI adding units 40 and 41 for adding a guard interval.

  First, in each MT (corresponding to MT1 and MT2 in the figure), the RF / IF units 23 and 24 convert the signals received by the corresponding antennas 21 and 22 to baseband signals S21 and S22, respectively. A known signal (corresponding to synchronization signals S72 and S73 described later) for establishing synchronization between the devices is inserted in the signal transmitted from the AP 11. With reference to this signal, the transmission timing analysis unit 34 generates transmission timing information S31 in accordance with an instruction from the AP 11 so that the signal arrival time to the AP 11 falls within the GI between the MTs. On the other hand, the GI removal units 25 and 26 perform burst unit synchronization with the baseband signals S21 and S22, and perform FFT window setting processing and GI removal processing. Then, the FFT units 27 and 28 convert the time signals S23 and S24 after the GI removal into subcarrier signals S25 and S26.

  Next, the transmission path estimation unit 29 estimates a transmission path gain S27 between the transmitting and receiving antennas using a known signal portion for transmission path estimation included in the subcarrier signals S25 and S26. Then, the equalization matrix generation unit 30 generates an equalization matrix S28 for channel separation based on the transmission line gain S27.

  Next, the signal separation unit 31 multiplies the subcarrier signals S25 and S26 after the FFT processing by the equalization matrix S28 to generate signals S29 and S30 for each channel. Finally, the demodulation units 32 and 33 demodulate the signals S29 and S30 of each channel, respectively.

  On the other hand, when transmitting a signal to the AP 11, in the MT (corresponding to MT1 and MT2 shown in the figure), first, the modulation units 36 and 37 perform predetermined modulation processing on the transmission signals A and B, and further the IFFT unit. 38 and 39 convert the modulation signals S33 and S34 on each subcarrier into time signals S35 and S36. Then, the GI adding units 40 and 41 add GI to the time signals S35 and S36 to generate signals S37 and S38.

  Next, in the timing adjustment / preamble insertion unit 35, “information indicating which SDM channel each mobile station uses to communicate” notified from the AP 11, that is, the channel configuration information S32 and the transmission timing information S31. The baseband signals S39 and S40 are generated by performing preamble insertion processing and transmission timing adjustment processing on the signals S37 and S38 after GI addition. Finally, the high-frequency signal converted by the RF / IF units 23 and 24 is transmitted to the AP 11 via the antennas 21 and 22. Note that, depending on the situation (for example, the number of antennas of the AP 11), there are cases where all the antennas of the MT cannot be used. The channel configuration information S32 is information shared by both prior to the data transfer between the AP and MT (the initial value of the transmission timing synchronization S31 is also the same). These signals are notified from the AP 11 to each MT at the negotiation stage prior to data transfer.

  FIG. 6 is a diagram illustrating the configuration of the AP 11 according to the first embodiment. The transmission / reception antennas 47 to 50, the high-frequency signal to baseband signal S50 to S53 conversion process, and the baseband signal (the illustrated baseband signal) RF / IF units 51 to 54 that perform conversion processing from the group S74 to high-frequency signals, guard interval (GI) removal units 55 to 58 that remove the GI and set the position of the FFT window, FFT units 59 to 62 that convert the time signals S54 to S57 into frequency signals S58 to S61, a transmission channel estimation unit 63 that estimates the transmission channel gain of each channel and each subcarrier, and a transmission channel gain that is a transmission channel estimation result An equalization matrix generation unit 64 that generates an equalization matrix S77 for channel separation from S76, a signal separation unit 65 that performs channel separation, Demodulating units 66 to 69 that demodulate the signals S62 to S65 of the subsequent channels, modulating units 70 and 71 that perform predetermined modulation processing on the transmission signal, and modulation signals S66 and S67 on the subcarriers are time signals S68. , S69 to convert IFFT units 72 and 73, GI adding units 74 and 75 for adding guard intervals, and synchronization signals S72 and S73 for establishing time synchronization of each MT, and generating signals S70, A synchronization signal generation unit 76 that performs control for inserting the synchronization signals S72 and S73 into S71, and an antenna selection unit 77 that performs control to allocate the signal after the synchronization signal insertion to each antenna.

First, in the AP 11, the RF / IF units 51 to 54 convert signals received by the corresponding antennas 47 to 50 into baseband signals S50 to S53, respectively. Then, GI removal unit 55 to 58, it synchronizes the bursts to the base band signal S50～S53, performs setting processing and GI removing process of the FFT window. Then, FFT sections 59 to 62 convert time signals S54 to S57 after GI removal into subcarrier signals S58 to S61.

  Next, the transmission path estimation unit 63 uses the known signal part for transmission path estimation or synchronization establishment included in the subcarrier signals S58 to S61 to set the transmission path gain S76 between the transmission and reception antennas in units of subcarriers. presume. In the equalization matrix generation unit 64, since the subcarrier signals S58 to S61 are in a state where a plurality of stations and a plurality of channels are mixed, the transmission line gain S76 and the channel configuration information S75 (notify each MT). Based on the channel configuration information S32), an equalization matrix S77 for channel separation is generated.

  Next, the signal separation unit 65 generates the signals S62 to S65 for each channel by multiplying the subcarrier signals S58 to S61 after the FFT processing by the equalization matrix S77. Finally, the demodulation units 66 to 69 demodulate the signals S62 to S65 of the respective channels.

  On the other hand, in the case of transmitting a signal to the MT, in the AP 11, first, the modulation units 70 and 71 perform predetermined modulation processing on the transmission signals A (addressed to MT1 and 2) and B (addressed to MT1 and 2). , IFFT units 72 and 73 convert modulated signals S66 and S67 on each subcarrier into time signals S68 and S69. Then, the GI adding units 74 and 75 add GI to the time signals S68 and S69 to generate signals S70 and S71.

  Next, the synchronization signal generator 76 generates a known signal for establishing synchronization with the MT, that is, the synchronization signals S72 and S73, and the synchronization signal is generated at a predetermined position of the signals S70 and S71 after the GI is added. Signals S72 and S73 are inserted. Since the AP 11 can detect the reception timing difference of each signal from each MT and the channel impulse response, the MT can adjust the transmission time so that the time difference of the incoming signal including the delayed wave is suppressed within the GI. In addition, synchronization signals S72 and S73 are generated. And the antenna selection part 77 performs control which allocates a transmission signal to each antenna. The AP 11 designates a channel to be used for each MT (corresponding to the channel configuration information S32: a different synchronization known signal is designated for each channel).

  As described above, in this embodiment, the AP designates the used channel and controls the transmission timing for each MT, and the time is set so that the arrival time difference of the signals on all the SDM channels falls within the GI. It was set as the structure which performs synchronous control. Thereby, on the AP side, FFT processing can be performed in a state in which the orthogonality of all signals received from a plurality of MTs is maintained. That is, on the AP side, simultaneous communication with a plurality of MTs can be realized while maintaining the reception characteristics of the one-to-one communication (prior art).

  In addition, although this Embodiment has demonstrated the case where one transmission series is transmitted from each transmission antenna, it is not limited to this, for example, by applying a beamforming function on the transmission side, A plurality of transmission sequences may be transmitted. In this case, the notified use channel is one of orthogonal channels obtained as a result of eigenvalue analysis by the receiving side. In the above description, the communication between the AT and the MT is described. However, the present invention is not limited to this, and the AP may be one of the MTs. That is, simultaneous communication between one MT and a plurality of MTs may be performed.

Embodiment 2. FIG.
FIG. 7 is a diagram showing the configuration of the wireless communication system according to the second embodiment that can implement the communication method according to the present invention, and uses the above-described AP and MT (see FIGS. 5 and 6 in the first embodiment). A specific example of the communication method is shown. Specifically, in the present embodiment, a wireless communication system employing CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) is assumed as a random access technique, and MT1, MT2, and MT12 belong to AP11, and each MT Is assumed to perform communication within the communicable range of the AP 11. In addition, the distance from each MT to AP11 is not necessarily the same.

  FIG. 8 is a diagram illustrating a frame configuration of a notification signal (Beacon) from the AP to each MT. The AP 11 periodically uses the notification information to transmit various information necessary for communication to the neighboring MTs. Notify them. As shown in the figure, the broadcast signal is composed of a packet type field, a destination address field, a source address field, a network identifier field, an information element field, and an error check field, and includes a packet type “Beacon”, a destination address, and a source address. , Network identifiers, and information elements such as time stamps for establishing time synchronization between the AP 11 and each MT, broadcast period, modulation method, etc., the number of antennas that the AP 11 can use, SDM channels, and group IDs , Information such as the transmission possible period of the MT belonging to the group ID. In this packet format, a field common to each wireless packet depending on the modulation / demodulation method is omitted.

  FIG. 9 is a diagram showing a frame configuration of a connection request from the MT to the AP. As shown in the figure, this connection request includes a packet type field, a destination address field, a transmission source address field, a network identifier field, an information element field, and an error check field. The packet type “connection request”, the destination address, and the transmission source Information such as an address, a network identifier, and information elements such as a registration request to a polling list, a network identifier, a usable transmission rate, a usable number of antennas, a number of SDM channels, and a transmission path estimation value are included.

  FIG. 10 is a diagram illustrating a frame configuration of a connection response from the AP to the MT. As shown in the figure, this connection response is composed of a packet type field, a destination address field, a transmission source address field, a network identifier field, an information element field, and an error check field. A packet type “connection response”, a destination address, a transmission source A plurality of MTs in which the number of antennas, SDM channels, group IDs, and APs that are allowed to be used for the MT based on information such as an address, network identifier, and information such as the previous connection request frame are assigned as the same group as information elements Predetermined time alignment information (information indicating how much the transmission is shifted from the time stamp included in the Beacon) and information such as transmission power information of each MT.

  Here, processing of each device constituting the wireless communication system of the second embodiment will be described in detail with reference to the drawings. FIG. 11 is a sequence diagram illustrating processing of each device configuring the wireless communication system according to the second embodiment. In FIG. 11, the horizontal axis represents the time axis, the arrow represents the signal from AP to MT or the signal from MT to AP, and each rectangle represents a packet. Further, the vertical overlap of the rectangles represents a state in which data or ACK is transmitted using each SDM channel.

  In FIG. 11, first, the AP 11 transmits the notification signal (Beacon) to each MT (corresponding to MT1, 2, 12), and MT1, 2, 12 receives the Beacon (step S1). As shown in FIG. 8, the Beacon includes a group ID that the AP 11 can use, an MT transmission possible period (time schedule information) when the AP 11 belongs to the group ID, and the like.

  Thereafter, for example, when MT1 wishes to connect to AP11, MT1 transmits a connection request to AP11 (step S2), and notifies basic information (see FIG. 9) of MT1 necessary for connection. . Upon receiving the connection request, the AP 11 transmits a connection response to the MT 1 as a response (step S3). For example, the number of antennas permitted to be used: two, SDM channels (CH1, CH3), and the predetermined number Time alignment information: Δt1, Group ID: Information such as transmission power information of group 1, MT1 is notified.

  Also, for example, when MT2 desires to connect to AP11, MT2 transmits a connection request to AP11 by the same process as MT1 (step S4), and basic information about MT2 (see FIG. 9) is transmitted. Notice. Upon receiving the connection request, the AP 11 transmits a connection response to the MT 2 as a response (step S5). For example, the number of antennas permitted to be used: two, SDM channels (CH2, CH4), and the predetermined number Information such as transmission power information of time alignment information: Δt2, group ID: group 1, MT2 is notified.

  Next, the AP 11 transmits the next Beacon to each MT (corresponding to MT1, 2, 12) after a predetermined time has elapsed since the previous Beacon transmission (step S6). This Beacon is a signal similar to the previous Beacon, and includes the MT transmittable period T1 belonging to the group 1. Note that MTs belonging to groups other than group 1 cannot execute transmission processing during T1.

  Next, in MT1 belonging to group 1, data is transmitted using the SDM channels CH1 and CH3 during the transmission available period T1 assigned as described above (step S7). At the same time, MT 2 belonging to group 1 also transmits data using the SDM channels CH2 and CH4 during the transmission possible period T1 assigned as described above (step S7). At this time, MT1 and MT2 perform time adjustment based on the time alignment information (Δt1, Δt2) so that the AP 11 can receive the data. Further, transmission power adjustment is performed based on the transmission power information notified by the AP 11.

  Then, when the data from MT1 and MT2 can be normally received, AP11 transmits ACK to MT1 and MT2 simultaneously for each SDM channel (step S8). MT 12 shown in the figure represents a mobile terminal to which no group ID is assigned or a mobile terminal in the case where there is no other mobile terminal having the same group ID.

  As described above, in the present embodiment, first, the AP includes information such as the number of usable antennas, the SDM channel and the group ID, and the MT transmittable period when the AP belongs to the group ID. Send. Then, the MT transmits information necessary for connection, such as the number of SDM channels and the number of used antennas, in the connection request, and the response includes the usable SDM channel, the transmittable period, etc. from the AP. Receive a connection response. Accordingly, simultaneous communication between the AP and a plurality of MTs can be realized, and uplink packets from the MT can be efficiently transmitted to the AP.

  In the present embodiment, as described above, the communication system adopting CSMA / CA has been described. However, the present invention is not limited to this, and the transmission / reception timing of each MT is scheduled by the centralized time management of the access point. The present invention can be similarly applied to a TDMA (Time Division Multiple Access) system. In this TDMA system, for example, information such as a desired SDM channel is notified to the AP using a request channel at the time of connection request or during communication. Further, in this embodiment, ACK replies are simultaneously performed toward two MTs, but various ACK reply methods are possible depending on the antenna configuration. That is, an efficient reply method is appropriately configured by combining the SDM channel and the STC channel.

  As described above, the communication apparatus according to the present invention is useful as a communication apparatus that configures a MIMO system that transmits two or more signals simultaneously using a plurality of antennas, and is particularly suitable for a wireless communication system that employs the SDM scheme. Is suitable.

It is a figure which shows the example of 1 structure of the radio | wireless communications system concerning this invention. It is a figure which shows a structure in case two MTs are communicating with AP simultaneously. It is a figure which shows the case where the arrival time difference of the signal from MT of 2 stations is settled in a guard interval. It is a figure which shows the case where the arrival time difference of the signal from MT of 2 stations does not fit in a guard interval. It is a figure which shows the structure of MT concerning this invention. It is a figure which shows the structure of AP concerning this invention. It is a figure which shows the structure of the radio | wireless communications system of Embodiment 2 which can implement | achieve the communication method concerning this invention. It is a figure which shows the flame | frame structure of the alerting | reporting signal (Beacon) from AP to each MT. It is a figure which shows the frame structure of the connection request | requirement from MT to AP. It is a figure which shows the frame structure of the connection response from AP to MT. FIG. 10 is a sequence diagram illustrating processing of each device configuring the wireless communication system according to the second embodiment.

Explanation of symbols

1,2,12 MT
3,4,5,6,7,8,9,10 Antenna 11 AP

Claims (2)

A control communication device that implements communication with a plurality of other communication devices that implement at least one antenna using an SDM (Space Division Multiplexing) channel corresponding to the plurality of antennas that the device itself implements, and a wireless communication system Configure
The control communication device is
Predetermined modulation processing, IFFT processing, and guard interval addition processing are performed on a plurality of signals to be transmitted to the plurality of other communication devices, and further, signals received from the plurality of other communication devices are received. Transmission signal generating means for generating a transmission signal by generating an individual synchronization known signal for each SDM channel based on timing and then inserting the synchronization known signal at a predetermined position of the signal after the addition of the guard interval; Antenna selection means for allocating transmission signals generated individually for each SDM channel to the respective antennas, and guarding the arrival time difference of reception signals on all SDM channels sent from the plurality of other communication devices. The transmission timings of the other communication devices are controlled using the synchronization known signal so as to be within the interval, and F In the case of the T process,
In the wireless communication system, the communication device which implements mutual communication using the control communication device and the SDM channel, wherein the at least one antenna is mounted,
A transmission timing analysis means for analyzing a transmission timing based on a synchronization known signal included in a signal transmitted from the control communication device;
A self-communication device that performs predetermined modulation processing, IFFT processing, and guard interval addition processing on a single or a plurality of signals to be transmitted to the control communication device, and then is notified from the control communication device. Timing adjustment means for adjusting the transmission timing of the transmission signal after adding the guard interval based on channel configuration information that is information indicating which SDM channel is used for communication and the analysis result;
A communication apparatus comprising: A first communication device mounting a plurality of antennas, and a plurality of second communication devices mounting at least one antenna, wherein the first communication device and the second communication device are connected to each antenna. In a wireless communication system that realizes mutual communication using a corresponding SDM (Space Division Multiplexing) channel,
The first communication device is
Predetermined modulation processing, IFFT processing, and guard interval addition processing are performed on a plurality of signals to be transmitted to the second communication device, and further, signals received from the plurality of second communication devices are received. Generate a known signal for synchronization for each SDM channel based on timing,
Thereafter, a transmission signal generating means for generating a transmission signal by inserting the known signal for synchronization at a predetermined position of the signal after addition of the guard interval;
Antenna selection means for assigning each antenna a transmission signal generated individually for each SDM channel;
With
The plurality of second communication devices are
Transmission timing analysis means for analyzing transmission timing based on the known signal for synchronization included in the signal transmitted from the first communication device;
A predetermined modulation process, an IFFT process, and a guard interval addition process are performed on a single signal or a plurality of signals to be transmitted to the first communication apparatus, and then notified from the first communication apparatus. Timing adjusting means for adjusting the transmission timing of the transmission signal after addition of the guard interval based on channel configuration information that is information indicating which SDM channel is used by the two communication devices and the analysis result When,
With
The first communication device is:
Radio communication characterized in that the transmission timing is controlled and FFT processing is performed so that arrival time differences of received signals on all SDM channels sent from the plurality of second communication devices fall within a guard interval. system.

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