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WO2023286158A1 - Wireless communication system and communication method - Google Patents

Wireless communication system and communication method Download PDF

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Publication number
WO2023286158A1
WO2023286158A1 PCT/JP2021/026305 JP2021026305W WO2023286158A1 WO 2023286158 A1 WO2023286158 A1 WO 2023286158A1 JP 2021026305 W JP2021026305 W JP 2021026305W WO 2023286158 A1 WO2023286158 A1 WO 2023286158A1
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WIPO (PCT)
Prior art keywords
signal
receiving device
transmitting device
communication system
jitter
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PCT/JP2021/026305
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French (fr)
Japanese (ja)
Inventor
淳 増野
斗煥 李
貴之 山田
裕文 笹木
康徳 八木
知哉 景山
Original Assignee
日本電信電話株式会社
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Application filed by 日本電信電話株式会社 filed Critical 日本電信電話株式会社
Priority to PCT/JP2021/026305 priority Critical patent/WO2023286158A1/en
Priority to JP2023534476A priority patent/JP7582478B2/en
Publication of WO2023286158A1 publication Critical patent/WO2023286158A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes

Definitions

  • the present invention relates to technology for spatially multiplexing radio signals.
  • Non-Patent Document 2 In MIMO communication, spatial multiplexing transmission/reception is generally performed on the premise of time synchronization between antenna ports. That is, the sampling timings of the transmitting antenna ports #1 to #N are the same, and according to the rules of the radio frame, etc., the signals to be spatially multiplexed are superimposed on the same sample range at each antenna port, and MIMO detection processing is performed on the receiving side.
  • the alias component that appears when the baseband signal is oversampled in digital signal processing is extracted with an appropriate BPF (Band-pass filter), and the RF frequency band signal There are also radios that transmit as (and vice versa, receive).
  • BPF Band-pass filter
  • GSa/s class high-speed sampling DAC operation is a prerequisite, and when transmission (reception) is performed from multiple antenna ports as in a MIMO antenna configuration, sampling between antenna ports Level synchronization becomes difficult.
  • the specifications are such that a maximum deviation of ⁇ 1 sample occurs between the antenna ports.
  • the disclosed technology aims to improve sample-level synchronization performance between antenna ports and to separate spatially multiplexed signals appropriately.
  • a technology disclosed herein is a wireless communication system that performs MIMO communication and includes a transmitting device and a receiving device, wherein the transmitting device transmits a wireless communication signal to the receiving device, and the receiving device communicates with the transmitting device. obtaining information indicating a maximum jitter value indicating sample synchronization capability between antenna ports of the transmitting device, based on the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device.
  • the sample-level synchronization performance between antenna ports can be improved, and spatially multiplexed signals can be separated appropriately.
  • FIG. 1 is a configuration diagram of a communication system according to an embodiment of the present invention
  • FIG. FIG. 4 is a diagram for explaining synchronization of sample levels between antenna ports
  • FIG. 4 is a first diagram for explaining how inter-symbol interference occurs
  • FIG. 10 is a second diagram for explaining how inter-symbol interference occurs.
  • FIG. 10 is a diagram for explaining a method of offsetting an FFT interval according to the first embodiment
  • FIG. 2 is a diagram illustrating a configuration example of a transmission device according to Example 1
  • FIG. 2 is a diagram illustrating a configuration example of a receiving device according to Example 1
  • FIG. FIG. 10 is a diagram illustrating a configuration example of a transmission device according to a second embodiment
  • FIG. 10 is a diagram illustrating a configuration example of a receiving device according to Example 2;
  • FIG. 11 is a diagram for explaining a method of offsetting an FFT interval according to the second embodiment;
  • FIG. 4 is a diagram for explaining a method of offsetting FFT intervals in uplink multi-user MIMO;
  • FIG. 11 is a diagram illustrating a configuration example of a wireless communication system according to a third embodiment;
  • FIG. 13 is a diagram illustrating a configuration example of a transmission device according to a fourth embodiment;
  • FIG. 11 is a diagram for explaining a method of offsetting an FFT interval according to the fourth embodiment;
  • FIG. 1 is a configuration diagram of a communication system according to an embodiment of the present invention. As shown in FIG. 1, the radio communication system according to this embodiment has transmitting apparatus 100 and receiving apparatus 200 .
  • FIG. 2 is a diagram for explaining synchronization of sample levels between antenna ports.
  • reception is performed based on the SYNC signal (synchronization signal) for time synchronization multiplexed on a specific antenna port (ch1 in the figure).
  • the FFT Fast Fourier Transform
  • the FFT interval is an interval used for signal demodulation or signal equalization.
  • CPrefix a cyclic prefix that duplicates the end of the signal waveform of the DATA part (data signal) ) is added before the DATA part, and after removing these on the receiving side, FFT is performed to obtain modulation symbols for each subcarrier.
  • CPrefix cyclic prefix
  • MIMO-OFDM if sample levels between antenna ports are not synchronized, sample positions of CPrefix shift for each MIMO channel, which causes inter-symbol interference.
  • FIG. 3 is a first diagram for explaining how inter-symbol interference occurs.
  • a SYNC signal is multiplexed to a specific antenna port (ch1 in the figure), and the receiver detects this to identify the start and end points of the following CPrefix and the start and end points of the DATA portion.
  • the receiver performs OFDM demodulation with the end point of CPrefix as the FFT start point, that is, the FFT section from the start point to the end point of the DATA section.
  • inter-symbol interference occurs when the received signal of the other antenna port is forward-shifted compared to the received signal of a specific reference antenna port.
  • FIG. 4 is a second diagram for explaining how inter-symbol interference occurs. As shown in FIG. 4, the case where the reference antenna port (ch1) is the rearmost is the case where the severest inter-symbol interference occurs.
  • FIG. 5 is a diagram for explaining a method of offsetting FFT intervals according to the first embodiment.
  • the transmitting apparatus 100 grasps in advance the maximum value of jitter that indicates sample synchronization capability between antenna ports.
  • the receiving device 200 acquires the information from the transmitting device 100 . At this time, let the jitter on the transmitting device 100 side be ⁇ Tx and the jitter on the receiving device 200 side be ⁇ Rx .
  • Receiving apparatus 200 determines the end point of CPrefix inserted by transmitting apparatus 100 as a countermeasure against delayed waves using a synchronization signal or the like for a specific antenna port, and a sample point of CPrefix that is at least 2 ( ⁇ Tx + ⁇ Rx ) samples ahead of that point. is the starting point of the FFT section, channel estimation, equalization and OFDM demodulation are performed. Since CPrefix is a cyclic shift signal in the DATA section, although phase rotation occurs, OFDM demodulation is possible without inter-symbol interference (ISI). The effect of phase rotation is compensated by channel estimation.
  • ISI inter-symbol interference
  • FIG. 6 is a diagram illustrating a configuration example of a transmission device according to the first embodiment;
  • the transmission device 100 includes a bit distribution circuit 110 and multiple transmission circuits 120 .
  • the number of transmission circuits 120 included in the transmission device 100 corresponds to the number of spatial multiplexing layers of the transmission signal.
  • Each transmission circuit 120 includes a transmission path estimation signal addition circuit 121, an m-QAM modulation circuit 122, a frequency multiplexing circuit 123, an IFFT circuit 124, a cyclic prefix addition circuit 125, a synchronization signal multiplexing circuit 126, and a transmission side.
  • a synchronization capability information transmission circuit 127 , a radio frame configuration circuit 128 , and a frequency conversion circuit 129 are provided.
  • the bit distribution circuit 110 distributes input bits to n MIMO channels for spatial multiplexing.
  • the m-QAM modulation circuit 122 of each MIMO channel performs symbol mapping for each subcarrier.
  • amplitude multilevel IQ quadrature modulation such as 16QAM and 64QAM is assumed, but other modulation schemes such as QPSK (4QAM) and BPSK may also be used.
  • a transmission path estimation signal output from a transmission path estimation signal addition circuit 121 is multiplexed on a specific subcarrier by a frequency multiplexing circuit 123, and then an IFFT circuit 124 for OFDM modulation is used. produces the time domain data signal.
  • the CyclicPrefix addition circuit 125 connects CPrefix, which is a copy of the latter half of the time domain data signal, to the head of the time domain data signal.
  • the length of CPrefix may generally be treated as a fixed parameter as a countermeasure against inter-symbol interference caused by delayed waves, but a separate control means may be provided.
  • the radio frame configuration circuit 128 embeds the control information sent by the transmission side synchronization capability information sending circuit 127 in the control information channel or the like.
  • the control information includes information indicating the maximum jitter value ( ⁇ Tx ) that indicates sample synchronization capability between antenna ports of transmitting apparatus 100 . Since the information indicating the maximum value of jitter ( ⁇ Tx ) is a value unique to the wireless device, transmitting apparatus 100 may report it only once in the initial connection stage before performing MIMO communication. good.
  • the synchronization signal (eg, modulated wave generated based on the M sequence) sent from the synchronization signal multiplexing circuit 126 is time-multiplexed at the beginning of the radio frame.
  • the radio frame configuration circuit 128 may multiplex the channel estimation signal at an appropriate location.
  • a signal of each MIMO channel is sent out from each antenna port through the frequency conversion circuit 129 .
  • the frequency conversion means an inexpensive configuration can be used in which an alias component that appears when the baseband signal is oversampled is extracted by an appropriate BPF and transmitted as a signal in the RF frequency band.
  • FIG. 7 is a diagram illustrating a configuration example of a receiving apparatus according to the first embodiment;
  • the receiving device 200 includes a bit mixing circuit 210 , multiple m-QAM demodulation circuits 220 , a MIMO equalization circuit 230 and multiple receiving circuits 240 .
  • the number of receiving circuits 240 included in the receiving apparatus 200 corresponds to the number of spatial multiplexing layers of the received signal.
  • Each receiving circuit 240 includes a transmission path estimation signal detection circuit 241, an FFT section determination circuit 242, a radio frame position detection circuit 243, a transmission side synchronization capability information detection circuit 244, a synchronization signal detection circuit 245, and an FFT circuit. 246, and a frequency demultiplexing circuit 247.
  • Synchronization signal detection circuit 245 detects a known synchronization signal (for example, a modulated wave generated based on the M-sequence) by sliding correlation or the like from the received signal of a specific MIMO channel (for example, ch1) in which the synchronization signal is multiplexed. do.
  • the radio frame position detection circuit 243 determines the position of the radio frame, that is, the start/end point of CPrefix and the start/end point of the DATA part of each OFDM symbol.
  • the transmission-side synchronization capability information detection circuit 244 acquires information indicating the maximum value ⁇ Tx of the jitter that indicates the sampling synchronization capability between the antenna ports of the transmission device 100 .
  • the radio frame position detection circuit 243 transmits this information to the reception circuits 240 of other MIMO channels for sharing within the reception device 200 .
  • the FFT interval determination circuit 242 determines the sample point of the CPrefix that is at least 2 ( ⁇ Tx + ⁇ Rx ) samples ahead of the end point of the identified CPrefix as the starting point of the FFT interval, and from there corresponds to the FFT size (2048 samples for 2048 FFT). is determined to be the FFT interval.
  • the FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
  • a frequency demultiplexing circuit 247 demultiplexes the transmission path estimation signal.
  • the transmission path estimation signal detection circuit 241 estimates information indicating the transmission path.
  • the information indicating the transmission path includes the amount of phase rotation due to the forward offset of the FFT starting point, in addition to the amplitude change and phase rotation in the spatial propagation.
  • the MIMO equalization circuit 230 performs MIMO interference cancellation/equalization on the data subcarriers of each MIMO channel separated by the frequency demultiplexing circuit 247 using transmission path information.
  • ZeroForcing in the frequency domain is well known as a method of interference cancellation/equalization, but other methods may be used.
  • the number of m-QAM demodulation circuits 220 provided in the receiving device 200 corresponds to the number of MIMO channels of the received signal after equalization by the MIMO equalization circuit 230 .
  • Each m-QAM demodulation circuit 220 converts the equalized signal of each MIMO channel into bits.
  • the bit mixing circuit 210 collects and outputs the bits distributed to each spatial multiplexing.
  • Transmitting apparatus 100 obtains the maximum value of jitter ⁇ Rx indicating sample synchronization capability between antenna ports of receiving apparatus 200 in the feedback link from receiving apparatus 200 to transmitting apparatus 100, and then obtains 2( ⁇ Tx CPrefix may be variably controlled so as to be + ⁇ Rx ) samples or more, and in that case, it is desirable to perform control in consideration of delayed wave tolerance. That is, if the longest delay of the expected delayed wave is Cp samples, transmitting apparatus 100 may set the length of CPrefix to Cp+2( ⁇ Tx + ⁇ Rx ) samples, for example.
  • communication assuming OFDM-MIMO is taken as an example, but it is also applicable to other MIMO transmission systems assuming block-type frequency domain signal processing.
  • DFT-s-OFDM DFT-spreading-OFDM
  • SC-FDE Single Carrier-Frequency Domain Equalization
  • a forward error correction code may be combined.
  • both the transmitting apparatus 100 and the receiving apparatus 200 assume n ⁇ n MIMO that implements n spatial multiplexing using n antennas, but the present invention is not particularly limited to this. It can be applied to a k ⁇ n MIMO antenna configuration with k transmission antennas and n reception antennas, or it can be applied to OAM radio multiplexing using UCA antennas, which is considered as one aspect of MIMO. .
  • the maximum values of jitter ⁇ Tx and ⁇ Rx indicate the sample synchronization capability between the antenna ports of transmitting apparatus 100 and receiving apparatus 200, they may be values that take into account the influence of other factors.
  • a raised-cosine filter with a low roll-off rate may be combined as a band-limiting filter in order to increase the frequency utilization efficiency. In such a case, the absolute value of jitter in the forward direction may be increased.
  • the maximum jitter value ⁇ Tx ( ⁇ Rx ) is notified as control information, it may be stored in advance in transmitting apparatus 100 and receiving apparatus 200 as known information.
  • Example 2 A second embodiment will be described below with reference to the drawings.
  • the second embodiment is different from the first embodiment in that a synchronization signal is multiplexed on each MIMO channel, and the receiving apparatus 200 directly detects the synchronization deviation amount of each antenna port with respect to a specific antenna port. Therefore, in the following description of the second embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
  • FIG. 8 is a diagram illustrating a configuration example of a transmission device according to a second embodiment.
  • Each transmission circuit 120 of the transmission device 100 according to the present embodiment has a configuration obtained by removing the transmission side synchronization capability information transmission circuit 127 from the transmission circuit 120 according to the first embodiment.
  • the transmitting apparatus 100 multiplexes the synchronization signal sent from the synchronization signal multiplexing circuit 126 in each MIMO channel at the beginning of the radio frame. Transmitting apparatus 100 may reuse a single synchronization signal in each MIMO channel by time-division processing that changes the MIMO channel that multiplexes the synchronization signal for each radio frame.
  • a plurality of excellent synchronization signals (for example, modulated waves generated based on Zadoff-Chu sequences) may be spatially multiplexed to each MIMO channel.
  • FIG. 9 is a diagram illustrating a configuration example of a receiving apparatus according to the second embodiment.
  • the FFT interval determination circuit 242 sets the end point of the CPrefix of the MIMO channel received at the earliest timing as the starting point of the FFT interval of each MIMO channel, and sets a sample interval corresponding to the FFT size (2048 samples for 2048 FFT) as the FFT interval. decide.
  • the FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
  • FIG. 10 is a diagram for explaining the method of offsetting the FFT interval according to the second embodiment.
  • Transmitting apparatus 100 multiplexes synchronization signals with good cross-correlation characteristics onto each MIMO channel.
  • Receiving apparatus 200 detects the sample position of the radio frame of each MIMO channel from the synchronization signal. As a result, OFDM demodulation can be performed with the end point of the CPrefix of the earliest arriving MIMO channel as the start point of the FFT interval.
  • Example 3 A third embodiment will be described below with reference to the drawings.
  • the third embodiment differs from the first embodiment in that the transmitter 100 individually transmits the maximum value of jitter to the receiver 200 . Therefore, in the following description of the third embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
  • the radio communication system it is possible to support uplink multi-user MIMO from a plurality of terminal stations (an example of the transmitting device 100) to a single base station (an example of the receiving device 200).
  • FIG. 11 is a diagram for explaining a method of offsetting FFT intervals in uplink multi-user MIMO.
  • synchronization signals are detected in the downlink, while transmission timing is controlled in consideration of transmission delay in order to achieve uplink synchronization, as described above. Synchronization of sample levels between antenna ports can be difficult.
  • the terminal design differs for each user, the inter-antenna port jitter ⁇ Tx may also have a different value ⁇ Tx_UEi for each user.
  • transmitting apparatus 100 and receiving apparatus 200 share information indicating ⁇ Tx_UEi using a control channel or the like during non-MIMO communication.
  • FIG. 12 is a diagram illustrating a configuration example of a wireless communication system according to the third embodiment.
  • each terminal station transmits a jitter value indicating the sample synchronization capability between the antenna ports of the transmitting apparatus 100 to the base station (receiving station) (an example of the receiving apparatus 200).
  • the transmitting apparatus 100 in the uplink need not include the synchronization signal multiplexing circuit 126 .
  • the jitter ⁇ Rx which indicates the sample synchronization capability between the antenna ports of the receiving apparatus 200 itself, is grasped in advance.
  • the FFT interval determination circuit 242 determines the starting point of the FFT interval of each MIMO channel by at least 2 ⁇ ( ⁇ MAX + ⁇ Rx ) samples ahead of the end point of CPrefix identified in a specific MIMO channel (for example, ch1), and performs FFT from there. A sample interval corresponding to the size (2048 samples for 2048 FFT) is determined as the FFT interval.
  • the FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
  • Example 4 A fourth embodiment will be described below with reference to the drawings.
  • the fourth embodiment differs from the first embodiment in that the transmitting apparatus 100 adds CyclicPostfix (CPostfix) in addition to CPrefix. Therefore, in the following description of the fourth embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
  • FIG. 13 is a diagram illustrating a configuration example of a transmission device according to the fourth embodiment.
  • Each transmission circuit 120 of the transmission device 100 according to the present embodiment includes a CyclicPrefix/Postfix addition circuit 1251 instead of the CyclicPrefix addition circuit 125 of the configuration of each transmission circuit 120 according to the first embodiment.
  • the CyclicPrefix/Postfix addition circuit 1251 concatenates CPrefix to the head of the time domain data signal and concatenates a cyclic postfix (hereinafter referred to as CPostfix) to the end of the time domain data signal.
  • CyclicPrefix/Postfix addition circuit 1251 acquires information indicating the maximum value ⁇ Rx of jitter indicating sample synchronization capability between antenna ports of receiving apparatus 200 in the feedback link from receiving apparatus 200 to transmitting apparatus 100, Setting or variable control is performed so that CPostfix is 2 ( ⁇ Tx + ⁇ Rx ) samples or more.
  • FIG. 14 is a diagram for explaining the method of offsetting the FFT interval according to the fourth embodiment.
  • the FFT interval determining circuit 242 uses the end point of the CPrefix identified by the synchronization signal as the starting point of the FFT interval, and determines a sample interval corresponding to the FFT size (2048 samples for 2048 FFT) as the FFT interval.
  • the FFT circuit 2216 performs FFT and decomposes into subcarriers based on the determined FFT interval.
  • the CyclicPrefix/Postfix adding circuit 1251 adds CPostfix in addition to CPrefix.
  • the forward offset can be absorbed by CPrefix, while the backward offset can be absorbed by CPostfix.
  • the receiver 200 does not require the transmission-side synchronization capability information detection circuit 244 . That is, receiving apparatus 200 does not need to acquire information indicating maximum jitter value ⁇ Tx indicating sample synchronization capability between antenna ports of transmitting apparatus 100 . This is because inter-symbol interference can be avoided by adding a sufficiently long CPostfix to the data signal.
  • Embodiments 1 to 4 may be combined as appropriate.
  • the first embodiment and the fourth embodiment may be combined.
  • transmitting apparatus 100 adds CPostfix of at least 2 ⁇ Tx samples to avoid inter-symbol interference due to jitter ⁇ ⁇ Tx , which indicates sample synchronization capability between antenna ports of transmitting apparatus 100 .
  • receiving apparatus 200 detects the synchronization signal from the end point of the identified CPrefix in a specific MIMO channel. A sample point at least 2 ⁇ Rx samples ahead is taken as the starting point of the FFT interval and OFDM demodulated.
  • a wireless communication system comprising a transmitting device and a receiving device and performing MIMO communication, The transmitting device transmits a wireless communication signal to the receiving device, The receiving device obtains information indicating a maximum value of jitter indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. Based on and, determining the FFT interval used for demodulation or signal equalization of the signal transmitted from the transmitting device, wireless communication system.
  • the transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel, At least 2 ( ⁇ Tx+ ⁇ Rx) samples from the end point of the cyclic prefix identified by the synchronization signal, based on the maximum jitter value ⁇ Tx of the transmitting device and the maximum jitter value ⁇ Rx of the receiving device.
  • the sample point of the cyclic prefix above is the starting point of the FFT interval
  • the transmitting device acquires information indicating a maximum jitter value ⁇ Rx of the receiving device from the receiving device, and sets the length of the cyclic prefix to at least 2 ( ⁇ Tx + ⁇ Rx) samples or more. 3.
  • the wireless communication system according to item 2. (Section 4) The transmitting device multiplexes a synchronization signal on each MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel, The receiving device detects the sample position of the radio frame of each MIMO channel from the synchronization signal, and sets the end point of the cyclic prefix of the earliest arriving MIMO channel as the starting point of the FFT interval.
  • the wireless communication system comprises a plurality of transmitters, each of the plurality of transmitting devices adds a cyclic prefix to a data signal of each MIMO channel in a radio frame of the signal, and transmits information indicating the maximum value of the jitter to the receiving device;
  • the receiving device receives information indicating the maximum value of the jitter from each of the plurality of transmitting devices, derives the maximum value ⁇ MAX of the jitter of each received transmitting device, and determines the jitter of the receiving device.
  • the starting point of the FFT interval is at least 2 ⁇ ( ⁇ MAX + ⁇ Rx ) samples ahead from the end point of the cyclic prefix. 5.
  • the wireless communication system according to any one of items 1 to 4. (Section 6)
  • the transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix and a cyclic postfix to the data signal of each MIMO channel,
  • the receiving device sets the end point of the cyclic prefix identified by the synchronization signal as the starting point of the FFT interval, 5.
  • the wireless communication system according to any one of items 1 to 4.
  • the transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel, and based on the maximum value ⁇ Tx of the jitter of the transmitting device , appending a cyclic postfix of length at least 2 ⁇ Tx samples, and The receiving device sets the starting point of the FFT interval to be at least 2 ⁇ Rx samples or more ahead from the end point of the cyclic prefix identified by the synchronization signal. 5.
  • the wireless communication system according to any one of items 1 to 4.
  • a communication method in a wireless communication system comprising a transmitting device and a receiving device, the transmitting device transmitting a wireless communication signal to the receiving device;
  • the receiving device acquires information indicating a maximum jitter value indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. and determining an FFT interval to be used for demodulation or signal equalization of the signal transmitted from the transmitting device, based on Communication method.
  • transmission device 110 bit distribution circuit 120 transmission circuit 121 transmission path estimation signal adding circuit 122 m-QAM modulation circuit 123 frequency multiplexing circuit 124 IFFT circuit 125 Cyclic Prefix adding circuit 1251 Cyclic Prefix/Postfix adding circuit 126 synchronous signal multiplexing circuit 127 transmitting side synchronization capability information transmission circuit 128 radio frame configuration circuit 129 frequency conversion circuit 200 receiver 210 bit mixing circuit 220 m-QAM demodulation circuit 230 MIMO equalization circuit 240 reception circuit 241 transmission path estimation signal detection circuit 242 FFT section determination circuit 243 radio frame Position detection circuit 244 Transmission side synchronization capability information detection circuit 245 Synchronization signal detection circuit 246 FFT circuit 247 Frequency demultiplexing circuit

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Abstract

This wireless communication system comprises a transmission device and a reception device, and carries out MIMO communication. The transmission device transmits a signal of wireless communication to the reception device. The reception device acquires information indicating maximum values of jitter representing sample synchronization performance between antenna ports of the transmission device, and determines an FFT section to be used for demodulation or equalization of the signal transmitted from the transmission device, on the basis of the maximum values of jitter of the transmission device and the reception device.

Description

無線通信システムおよび通信方法Wireless communication system and communication method
　本発明は、無線信号を空間多重伝送する技術に関連するものである。 The present invention relates to technology for spatially multiplexing radio signals.
　近年、無線通信の需要の高まりに対してさまざまな高速化手段が検討されている。有効な手段の１つは空間多重により通信路を等価的に増やす手法が挙げられ、複数のアンテナ構成を用いたＭＩＭＯ通信、特にＯＦＤＭ（Orthogonal Frequency Domain Multiplexing）変調と組み合わせたＯＦＤＭ－ＭＩＭＯ方式は無線ＬＡＮやＬＴＥ／５Ｇといった無線通信システムにおいて実用化されている（非特許文献１）。 In recent years, various speed-enhancing methods have been considered in response to the increasing demand for wireless communication. One of the effective means is to equivalently increase the number of communication channels by spatial multiplexing. MIMO communication using multiple antenna configurations, especially OFDM (Orthogonal Frequency Domain Multiplexing) modulation combined with OFDM-MIMO system is wireless. It has been put into practical use in wireless communication systems such as LAN and LTE/5G (Non-Patent Document 1).
　ＭＩＭＯ通信では、一般にアンテナポート間の時間同期を前提とした空間多重送受信が行われる。すなわち送信アンテナポート♯１－♯Ｎのサンプリングタイミングは一致しており、無線フレーム等の規則に従い、空間多重対象の信号は各アンテナポートで同一のサンプル範囲に重畳され、受信側ではＭＩＭＯ検出処理を行う（非特許文献２）。 In MIMO communication, spatial multiplexing transmission/reception is generally performed on the premise of time synchronization between antenna ports. That is, the sampling timings of the transmitting antenna ports #1 to #N are the same, and according to the rules of the radio frame, etc., the signals to be spatially multiplexed are superimposed on the same sample range at each antenna port, and MIMO detection processing is performed on the receiving side. (Non-Patent Document 2).
　高速化に有効なもう１つの手段として広帯域化が挙げられるが、使用可能な電波資源のひっ迫に伴い、広帯域が使用可能なＲＦ周波数帯は高周波数化の一途にある。ベースバンド信号を実際に送信するＲＦ周波数までアップコンバートするにあたり、ＩＦ周波数を経由したスーパーヘテロダイン方式などの伝統的手法ではアナログデバイスを多く含む。低周波数帯に比べ高周波数帯アナログデバイスは高価であることから、一般的に無線機コストは高まり、無線通信システムや特に端末装置の普及を阻害する要因となる。 Another effective way to increase speed is to increase the frequency band, but with the shortage of available radio wave resources, the RF frequency band that can be used for a wide band continues to increase in frequency. In up-converting the baseband signal to the RF frequency at which it is actually transmitted, traditional methods such as superheterodyne via the IF frequency involve many analog devices. High-frequency band analog devices are more expensive than low-frequency band analog devices, which generally increases the cost of wireless devices, which is a factor that hinders the spread of wireless communication systems and, in particular, terminal devices.
　近年では、低廉な高周波数無線機の実現手段として、デジタル信号処理においてベースバンド信号をオーバーサンプリングした際に出現するエイリアス成分を適当なＢＰＦ（Band-pass filter）で抽出し、ＲＦ周波数帯の信号として送信（またその逆で受信）を行う無線機も出現している。一方、そのような低廉な無線機構成では、ＧＳａ／ｓクラスの高速サンプリングのＤＡＣ動作が前提となり、ＭＩＭＯアンテナ構成のように複数アンテナポートからの送信（受信）を行う場合、アンテナポート間のサンプルレベルの同期が難しくなる。例えば、非特許文献３の無線機の事例では、アンテナポート間で最大±１サンプルのずれが発生する仕様となっている。 In recent years, as a means of realizing low-cost high-frequency radio equipment, the alias component that appears when the baseband signal is oversampled in digital signal processing is extracted with an appropriate BPF (Band-pass filter), and the RF frequency band signal There are also radios that transmit as (and vice versa, receive). On the other hand, in such a low-cost wireless device configuration, GSa/s class high-speed sampling DAC operation is a prerequisite, and when transmission (reception) is performed from multiple antenna ports as in a MIMO antenna configuration, sampling between antenna ports Level synchronization becomes difficult. For example, in the case of the wireless device in Non-Patent Document 3, the specifications are such that a maximum deviation of ±1 sample occurs between the antenna ports.
　上記のように、原理的にはＭＩＭＯ通信において、空間フィルタリング等の信号処理により空間多重された信号を分離することができるが、アンテナポート間でサンプルレベルの同期が難しい場合、分離性能の特性劣化を招く問題がある。 As described above, in principle, in MIMO communication, spatially multiplexed signals can be separated by signal processing such as spatial filtering. There is a problem that invites
　開示の技術は、アンテナポート間のサンプルレベルの同期性能を向上し、空間多重信号を適切に分離することを目的とする。 The disclosed technology aims to improve sample-level synchronization performance between antenna ports and to separate spatially multiplexed signals appropriately.
　開示の技術は、送信装置と受信装置とを備え、ＭＩＭＯ通信を行う無線通信システムであって、前記送信装置は、無線通信の信号を前記受信装置に送信し、前記受信装置は、前記送信装置のアンテナポート間のサンプル同期能力を示すジッタの最大値を示す情報を取得して、前記送信装置の前記ジッタの最大値と、前記受信装置の前記ジッタの最大値とに基づいて、前記送信装置から送信された前記信号の復調または信号等化に用いるＦＦＴ区間を決定する無線通信システムである。 A technology disclosed herein is a wireless communication system that performs MIMO communication and includes a transmitting device and a receiving device, wherein the transmitting device transmits a wireless communication signal to the receiving device, and the receiving device communicates with the transmitting device. obtaining information indicating a maximum jitter value indicating sample synchronization capability between antenna ports of the transmitting device, based on the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device A wireless communication system for determining an FFT interval to be used for demodulation or signal equalization of the signal transmitted from.
　アンテナポート間のサンプルレベルの同期性能を向上し、空間多重信号を適切に分離することができる。 　The sample-level synchronization performance between antenna ports can be improved, and spatially multiplexed signals can be separated appropriately.
本発明の実施の形態における通信システムの構成図である。1 is a configuration diagram of a communication system according to an embodiment of the present invention; FIG. アンテナポート間のサンプルレベルの同期について説明するための図である。FIG. 4 is a diagram for explaining synchronization of sample levels between antenna ports; シンボル間干渉の発生状況について説明するための第一の図である。FIG. 4 is a first diagram for explaining how inter-symbol interference occurs; シンボル間干渉の発生状況について説明するための第二の図である。FIG. 10 is a second diagram for explaining how inter-symbol interference occurs. 実施例１に係るＦＦＴ区間のオフセット方法について説明するための図である。FIG. 10 is a diagram for explaining a method of offsetting an FFT interval according to the first embodiment; FIG. 実施例１に係る送信装置の構成例を示す図である。2 is a diagram illustrating a configuration example of a transmission device according to Example 1; FIG. 実施例１に係る受信装置の構成例を示す図である。2 is a diagram illustrating a configuration example of a receiving device according to Example 1; FIG. 実施例２に係る送信装置の構成例を示す図である。FIG. 10 is a diagram illustrating a configuration example of a transmission device according to a second embodiment; 実施例２に係る受信装置の構成例を示す図である。FIG. 10 is a diagram illustrating a configuration example of a receiving device according to Example 2; 実施例２に係るＦＦＴ区間のオフセット方法について説明するための図である。FIG. 11 is a diagram for explaining a method of offsetting an FFT interval according to the second embodiment; 上りリンクマルチユーザＭＩＭＯにおけるＦＦＴ区間のオフセット方法について説明するための図である。FIG. 4 is a diagram for explaining a method of offsetting FFT intervals in uplink multi-user MIMO; 実施例３に係る無線通信システムの構成例を示す図である。FIG. 11 is a diagram illustrating a configuration example of a wireless communication system according to a third embodiment; 実施例４に係る送信装置の構成例を示す図である。FIG. 13 is a diagram illustrating a configuration example of a transmission device according to a fourth embodiment; 実施例４に係るＦＦＴ区間のオフセット方法について説明するための図である。FIG. 11 is a diagram for explaining a method of offsetting an FFT interval according to the fourth embodiment;
　以下、図面を参照して本発明の実施の形態（本実施の形態）を説明する。以下で説明する実施の形態は一例に過ぎず、本発明が適用される実施の形態は、以下の実施の形態に限られるわけではない。 An embodiment (this embodiment) of the present invention will be described below with reference to the drawings. The embodiments described below are merely examples, and embodiments to which the present invention is applied are not limited to the following embodiments.
　（システム構成）
　図１は、本発明の実施の形態における通信システムの構成図である。図１に示すように、本実施の形態における無線通信システムは、送信装置１００と受信装置２００を有する。 (System configuration)
FIG. 1 is a configuration diagram of a communication system according to an embodiment of the present invention. As shown in FIG. 1, the radio communication system according to this embodiment has transmitting apparatus 100 and receiving apparatus 200 .
　次に、本実施形態に係るアンテナポート間のサンプルレベルの同期について、実施例１から実施例５までの例を用いて説明する。 Next, sample level synchronization between antenna ports according to the present embodiment will be described using examples 1 to 5.
　図２は、アンテナポート間のサンプルレベルの同期について説明するための図である。例えば、図２に示すように各チャネルのアンテナポート間で完全に同期されている場合、特定のアンテナポート（図ではｃｈ１）に多重された時間同期用のＳＹＮＣ信号（同期信号）を元に受信機側で同期をとることで、各アンテナポートの受信信号に適用するＦＦＴ（Fast Fourier Transform）区間には自シンボルのみが含まれている状況となり、すなわちシンボル間干渉は発生しない。ＦＦＴ区間は、信号の復調または信号等化に用いられる区間である。なお、移動無線通信を想定したＯＦＤＭ方式の場合、遅延波に起因するシンボル間干渉を抑圧するために、ＤＡＴＡ部（データ信号）の信号波形の末尾を複製した巡回プレフィックス（ＣｙｃｌｉｃＰｒｅｆｉｘ）（以下、ＣＰｒｅｆｉｘとする）をＤＡＴＡ部の前に付加し、受信側でこれらを除去した上でＦＦＴを行いサブキャリア毎の変調シンボルを取得するのが一般的である。しかし、ＭＩＭＯ－ＯＦＤＭにおいてアンテナポート間のサンプルレベルの同期がとれていない場合、ＭＩＭＯチャンネルごとにＣＰｒｅｆｉｘのサンプル位置がずれるため、シンボル間干渉を引き起こす要因となる。 FIG. 2 is a diagram for explaining synchronization of sample levels between antenna ports. For example, when the antenna ports of each channel are completely synchronized as shown in FIG. 2, reception is performed based on the SYNC signal (synchronization signal) for time synchronization multiplexed on a specific antenna port (ch1 in the figure). By synchronizing on the equipment side, the FFT (Fast Fourier Transform) interval applied to the received signal of each antenna port contains only its own symbol, that is, no inter-symbol interference occurs. The FFT interval is an interval used for signal demodulation or signal equalization. In the case of the OFDM system assuming mobile radio communication, in order to suppress inter-symbol interference caused by delayed waves, a cyclic prefix (hereinafter referred to as CPrefix) that duplicates the end of the signal waveform of the DATA part (data signal) ) is added before the DATA part, and after removing these on the receiving side, FFT is performed to obtain modulation symbols for each subcarrier. However, in MIMO-OFDM, if sample levels between antenna ports are not synchronized, sample positions of CPrefix shift for each MIMO channel, which causes inter-symbol interference.
　図３は、シンボル間干渉の発生状況について説明するための第一の図である。図２と同様に、特定のアンテナポート（図ではｃｈ１）にＳＹＮＣ信号が多重され、受信機はこれを検出して、後続するＣＰｒｅｆｉｘの始点、終点、ＤＡＴＡ部の始点、終点を同定する。受信機は、通常動作として、ＣＰｒｅｆｉｘの終点をＦＦＴの始点、すなわちＤＡＴＡ部の始点から終点までをＦＦＴ区間としてＯＦＤＭ復調する。アンテナポート間でサンプルレベルの同期がとれていない場合、基準となる特定のアンテナポートの受信信号に比べて他のアンテナポートの受信信号が前方にシフトしていると、シンボル間干渉が発生する。 FIG. 3 is a first diagram for explaining how inter-symbol interference occurs. As in FIG. 2, a SYNC signal is multiplexed to a specific antenna port (ch1 in the figure), and the receiver detects this to identify the start and end points of the following CPrefix and the start and end points of the DATA portion. As a normal operation, the receiver performs OFDM demodulation with the end point of CPrefix as the FFT start point, that is, the FFT section from the start point to the end point of the DATA section. When sample levels are not synchronized between antenna ports, inter-symbol interference occurs when the received signal of the other antenna port is forward-shifted compared to the received signal of a specific reference antenna port.
　このとき、送信機側のジッタを±ΔＴｘ、受信機側のジッタを±ΔＲｘとすると、最大２(ΔＴｘ＋ΔＲｘ)サンプルのシフトが生じる可能性がある。 At this time, if the jitter on the transmitter side is ±Δ Tx and the jitter on the receiver side is ±Δ Rx , a shift of up to 2 (Δ Tx +Δ Rx ) samples can occur.
　図４は、シンボル間干渉の発生状況について説明するための第二の図である。図４に示すように、基準となるアンテナポート（ｃｈ１）が最も後方となるケースが最も厳しいシンボル間干渉が発生するケースである。 FIG. 4 is a second diagram for explaining how inter-symbol interference occurs. As shown in FIG. 4, the case where the reference antenna port (ch1) is the rearmost is the case where the severest inter-symbol interference occurs.
　（実施例１に係るＦＦＴ区間のオフセット方法）
　図５は、実施例１に係るＦＦＴ区間のオフセット方法について説明するための図である。本実施例では、送信装置１００が、アンテナポート間のサンプル同期能力を示すジッタの最大値を事前に把握しておく。受信装置２００は送信装置１００から当該情報を取得する。このとき、送信装置１００側のジッタを±ΔＴｘ、受信装置２００側のジッタを±ΔＲｘとする。 (Offset method of FFT interval according to embodiment 1)
FIG. 5 is a diagram for explaining a method of offsetting FFT intervals according to the first embodiment. In this embodiment, the transmitting apparatus 100 grasps in advance the maximum value of jitter that indicates sample synchronization capability between antenna ports. The receiving device 200 acquires the information from the transmitting device 100 . At this time, let the jitter on the transmitting device 100 side be ±Δ Tx and the jitter on the receiving device 200 side be ±Δ Rx .
　受信装置２００は、特定のアンテナポートの同期信号等により遅延波対策用に送信装置１００が挿入するＣＰｒｅｆｉｘの終点を決定し、そこから少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上前方のＣＰｒｅｆｉｘのサンプル点をＦＦＴ区間の始点として、伝送路推定、等化およびＯＦＤＭ復調を行う。なお、ＣＰｒｅｆｉｘはＤＡＴＡ部の巡回シフト信号のため、位相回転はするが、シンボル間干渉(ＩＳＩ：Inter Symbol Interference)が無い状態でＯＦＤＭ復調可能となる。前記位相回転の影響は伝送路推定によって補償される。 Receiving apparatus 200 determines the end point of CPrefix inserted by transmitting apparatus 100 as a countermeasure against delayed waves using a synchronization signal or the like for a specific antenna port, and a sample point of CPrefix that is at least 2 (Δ Tx +Δ Rx ) samples ahead of that point. is the starting point of the FFT section, channel estimation, equalization and OFDM demodulation are performed. Since CPrefix is a cyclic shift signal in the DATA section, although phase rotation occurs, OFDM demodulation is possible without inter-symbol interference (ISI). The effect of phase rotation is compensated by channel estimation.
　（実施例１に係る送信装置の構成例）
　図６は、実施例１に係る送信装置の構成例を示す図である。送信装置１００は、ビット分配回路１１０と、複数の送信回路１２０と、を備える。送信装置１００が備える送信回路１２０の数は、送信信号の空間多重レイヤ数に対応している。各送信回路１２０は、伝送路推定用信号付加回路１２１と、ｍ－ＱＡＭ変調回路１２２と、周波数多重回路１２３と、ＩＦＦＴ回路１２４と、ＣｙｃｌｉｃＰｒｅｆｉｘ付加回路１２５と、同期信号多重回路１２６と、送信側同期能力情報送出回路１２７と、無線フレーム構成回路１２８と、周波数変換回路１２９と、を備える。 (Configuration example of transmission device according to embodiment 1)
FIG. 6 is a diagram illustrating a configuration example of a transmission device according to the first embodiment; The transmission device 100 includes a bit distribution circuit 110 and multiple transmission circuits 120 . The number of transmission circuits 120 included in the transmission device 100 corresponds to the number of spatial multiplexing layers of the transmission signal. Each transmission circuit 120 includes a transmission path estimation signal addition circuit 121, an m-QAM modulation circuit 122, a frequency multiplexing circuit 123, an IFFT circuit 124, a cyclic prefix addition circuit 125, a synchronization signal multiplexing circuit 126, and a transmission side. A synchronization capability information transmission circuit 127 , a radio frame configuration circuit 128 , and a frequency conversion circuit 129 are provided.
　ビット分配回路１１０は、入力ビットを空間多重用のｎ個のＭＩＭＯチャンネルに分配する。各ＭＩＭＯチャンネルのｍ－ＱＡＭ変調回路１２２は、サブキャリア毎のシンボルマッピングを行う。 The bit distribution circuit 110 distributes input bits to n MIMO channels for spatial multiplexing. The m-QAM modulation circuit 122 of each MIMO channel performs symbol mapping for each subcarrier.
　本実施例では、１６ＱＡＭや６４ＱＡＭなどの振幅多値のＩＱ直交変調を想定しているが、ＱＰＳＫ（４ＱＡＭ）やＢＰＳＫなど他の変調方式でも良い。これらのデータサブキャリアのほかに、特定サブキャリアには伝送路推定用信号付加回路１２１より出力される伝送路推定用信号が周波数多重回路１２３で多重された上で、ＯＦＤＭ変調用のＩＦＦＴ回路１２４が時間領域データ信号を生成する。 In this embodiment, amplitude multilevel IQ quadrature modulation such as 16QAM and 64QAM is assumed, but other modulation schemes such as QPSK (4QAM) and BPSK may also be used. In addition to these data subcarriers, a transmission path estimation signal output from a transmission path estimation signal addition circuit 121 is multiplexed on a specific subcarrier by a frequency multiplexing circuit 123, and then an IFFT circuit 124 for OFDM modulation is used. produces the time domain data signal.
　続いてＣｙｃｌｉｃＰｒｅｆｉｘ付加回路１２５は、時間領域データ信号の後半部を複写したＣＰｒｅｆｉｘを時間領域データ信号の先頭に連結する。ＣＰｒｅｆｉｘの長さは一般的に遅延波によるシンボル間干渉対策として固定的なパラメータとして扱ってもよいが、別途制御する手段を設けても良い。 Subsequently, the CyclicPrefix addition circuit 125 connects CPrefix, which is a copy of the latter half of the time domain data signal, to the head of the time domain data signal. The length of CPrefix may generally be treated as a fixed parameter as a countermeasure against inter-symbol interference caused by delayed waves, but a separate control means may be provided.
　続いて、無線フレーム構成回路１２８は、送信側同期能力情報送出回路１２７により送出される制御情報を制御情報チャネル等に埋め込む。制御情報は、送信装置１００のアンテナポート間のサンプル同期能力を示すジッタの最大値（±ΔＴｘ）を示す情報を含む。なお、ジッタの最大値（±ΔＴｘ）を示す情報は、無線機固有の値であるため、送信装置１００は、ＭＩＭＯ通信を実施する前の初期接続段階において１回のみ報知するようにしても良い。 Subsequently, the radio frame configuration circuit 128 embeds the control information sent by the transmission side synchronization capability information sending circuit 127 in the control information channel or the like. The control information includes information indicating the maximum jitter value (±Δ Tx ) that indicates sample synchronization capability between antenna ports of transmitting apparatus 100 . Since the information indicating the maximum value of jitter (±Δ Tx ) is a value unique to the wireless device, transmitting apparatus 100 may report it only once in the initial connection stage before performing MIMO communication. good.
　また、特定のＭＩＭＯチャンネル（たとえばｃｈ１）については同期信号多重回路１２６から送出される同期信号（たとえばＭ系列を元に生成される変調波）が無線フレームの先頭に時間多重等される。なお、前述の伝送路推定用信号を時間領域で設計する場合は、無線フレーム構成回路１２８が適当な場所に伝送路推定用信号を多重しても良い。 Also, for a specific MIMO channel (eg, ch1), the synchronization signal (eg, modulated wave generated based on the M sequence) sent from the synchronization signal multiplexing circuit 126 is time-multiplexed at the beginning of the radio frame. When the above-described channel estimation signal is designed in the time domain, the radio frame configuration circuit 128 may multiplex the channel estimation signal at an appropriate location.
　各ＭＩＭＯチャンネルの信号は、周波数変換回路１２９を経て、それぞれのアンテナポートから送出される。周波数変換手段としては、ベースバンド信号をオーバーサンプリングした際に出現するエイリアス成分を適当なＢＰＦで抽出し、ＲＦ周波数帯の信号として送信する低廉な構成も取りえる。 A signal of each MIMO channel is sent out from each antenna port through the frequency conversion circuit 129 . As the frequency conversion means, an inexpensive configuration can be used in which an alias component that appears when the baseband signal is oversampled is extracted by an appropriate BPF and transmitted as a signal in the RF frequency band.
　（実施例１に係る受信装置の構成例）
　図７は、実施例１に係る受信装置の構成例を示す図である。受信装置２００は、ビット混合回路２１０と、複数のｍ－ＱＡＭ復調回路２２０と、ＭＩＭＯ等化回路２３０と、複数の受信回路２４０と、を備える。受信装置２００が備える受信回路２４０の数は、受信信号の空間多重レイヤ数に対応している。各受信回路２４０は、伝送路推定用信号検出回路２４１と、ＦＦＴ区間決定回路２４２と、無線フレーム位置検出回路２４３と、送信側同期能力情報検出回路２４４と、同期信号検出回路２４５と、ＦＦＴ回路２４６と、周波数多重分離回路２４７と、を備える。 (Configuration example of receiving device according to embodiment 1)
FIG. 7 is a diagram illustrating a configuration example of a receiving apparatus according to the first embodiment; The receiving device 200 includes a bit mixing circuit 210 , multiple m-QAM demodulation circuits 220 , a MIMO equalization circuit 230 and multiple receiving circuits 240 . The number of receiving circuits 240 included in the receiving apparatus 200 corresponds to the number of spatial multiplexing layers of the received signal. Each receiving circuit 240 includes a transmission path estimation signal detection circuit 241, an FFT section determination circuit 242, a radio frame position detection circuit 243, a transmission side synchronization capability information detection circuit 244, a synchronization signal detection circuit 245, and an FFT circuit. 246, and a frequency demultiplexing circuit 247.
　同期信号が多重された特定のＭＩＭＯチャンネル（たとえばｃｈ１）の受信信号に対し、同期信号検出回路２４５は、スライディング相関等により既知の同期信号（たとえばＭ系列を元に生成される変調波）を検出する。無線フレーム位置検出回路２４３は、無線フレームの位置、すなわち各ＯＦＤＭシンボルのＣＰｒｅｆｉｘの始点・終点およびＤＡＴＡ部の始点・終点を決定する。 Synchronization signal detection circuit 245 detects a known synchronization signal (for example, a modulated wave generated based on the M-sequence) by sliding correlation or the like from the received signal of a specific MIMO channel (for example, ch1) in which the synchronization signal is multiplexed. do. The radio frame position detection circuit 243 determines the position of the radio frame, that is, the start/end point of CPrefix and the start/end point of the DATA part of each OFDM symbol.
　送信側同期能力情報検出回路２４４は、送信装置１００のアンテナポート間のサンプル同期能力を示すジッタの最大値±ΔＴｘを示す情報を取得する。無線フレーム位置検出回路２４３は、受信装置２００内で共有するため、これらの情報を他のＭＩＭＯチャンネルの受信回路２４０に送信する。 The transmission-side synchronization capability information detection circuit 244 acquires information indicating the maximum value ±Δ Tx of the jitter that indicates the sampling synchronization capability between the antenna ports of the transmission device 100 . The radio frame position detection circuit 243 transmits this information to the reception circuits 240 of other MIMO channels for sharing within the reception device 200 .
　続いて、ＦＦＴ区間決定回路２４２は、同定したＣＰｒｅｆｉｘの終点から少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上前方のＣＰｒｅｆｉｘのサンプル点をＦＦＴ区間の始点として、そこからＦＦＴサイズ（２０４８ＦＦＴなら２０４８サンプル）相当のサンプル区間をＦＦＴ区間に決定する。ＦＦＴ回路２４６は、決定されたＦＦＴ区間に基づいて、ＦＦＴを行い、サブキャリアに分解する。 Subsequently, the FFT interval determination circuit 242 determines the sample point of the CPrefix that is at least 2 (Δ Tx +Δ Rx ) samples ahead of the end point of the identified CPrefix as the starting point of the FFT interval, and from there corresponds to the FFT size (2048 samples for 2048 FFT). is determined to be the FFT interval. The FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
　周波数多重分離回路２４７は、伝送路推定用信号を分離する。伝送路推定用信号検出回路２４１は、伝送路を示す情報を推定する。ここで、伝送路を示す情報は、空間伝搬における振幅変化・位相回転に加え、前述のＦＦＴ開始点を前方へオフセットしたことによる位相回転量も含む。 A frequency demultiplexing circuit 247 demultiplexes the transmission path estimation signal. The transmission path estimation signal detection circuit 241 estimates information indicating the transmission path. Here, the information indicating the transmission path includes the amount of phase rotation due to the forward offset of the FFT starting point, in addition to the amplitude change and phase rotation in the spatial propagation.
　ＭＩＭＯ等化回路２３０は、周波数多重分離回路２４７によって分離された各ＭＩＭＯチャンネルのデータサブキャリアに、伝送路情報を用いてＭＩＭＯ干渉除去・等化を行う。干渉除去・等化の方法としては、周波数領域におけるＺｅｒｏＦｏｒｃｉｎｇなどが良く知られるが、他の方法でも良い。 The MIMO equalization circuit 230 performs MIMO interference cancellation/equalization on the data subcarriers of each MIMO channel separated by the frequency demultiplexing circuit 247 using transmission path information. ZeroForcing in the frequency domain is well known as a method of interference cancellation/equalization, but other methods may be used.
　また、受信装置２００が備えるｍ－ＱＡＭ復調回路２２０の数は、ＭＩＭＯ等化回路２３０による等化後の受信信号のＭＩＭＯチャンネルの数に相当する。各ｍ－ＱＡＭ復調回路２２０は、等化後の各ＭＩＭＯチャンネルの信号を、ビットに変換する。ビット混合回路２１０は、各空間多重に分配されたビットをまとめて、出力する。 Also, the number of m-QAM demodulation circuits 220 provided in the receiving device 200 corresponds to the number of MIMO channels of the received signal after equalization by the MIMO equalization circuit 230 . Each m-QAM demodulation circuit 220 converts the equalized signal of each MIMO channel into bits. The bit mixing circuit 210 collects and outputs the bits distributed to each spatial multiplexing.
　なお、送信装置１００は、受信装置２００から送信装置１００へのフィードバックリンクにおいて、受信装置２００のアンテナポート間のサンプル同期能力を示すジッタの最大値±ΔＲｘを入手した上で、２(ΔＴｘ＋ΔＲｘ)サンプル以上となるようにＣＰｒｅｆｉｘを可変制御しても良く、その際は遅延波耐力も考慮した制御とすることが望ましい。すなわち、想定される遅延波の最長遅延がＣｐサンプルだとすれば、送信装置１００は、たとえばＣＰｒｅｆｉｘの長さをＣｐ＋２(ΔＴｘ＋ΔＲｘ)サンプルとしても良い。 Transmitting apparatus 100 obtains the maximum value of jitter ±Δ Rx indicating sample synchronization capability between antenna ports of receiving apparatus 200 in the feedback link from receiving apparatus 200 to transmitting apparatus 100, and then obtains 2(Δ Tx CPrefix may be variably controlled so as to be +Δ Rx ) samples or more, and in that case, it is desirable to perform control in consideration of delayed wave tolerance. That is, if the longest delay of the expected delayed wave is Cp samples, transmitting apparatus 100 may set the length of CPrefix to Cp+2(Δ Tx +Δ Rx ) samples, for example.
　本実施例では、ＯＦＤＭ－ＭＩＭＯを想定した通信を事例に挙げたが、そのほかのブロック型の周波数領域信号処理を前提としたＭＩＭＯ伝送方式にも適用可能である。たとえば、ＤＦＴ－ｓ－ＯＦＤＭ（DFT-spreading-OFDM）、ＳＣ－ＦＤＥ(Single Carrier-Frequency Domain Equalization)などが考えられる。また、前方誤り訂正符号を組合せても良い。 In this embodiment, communication assuming OFDM-MIMO is taken as an example, but it is also applicable to other MIMO transmission systems assuming block-type frequency domain signal processing. For example, DFT-s-OFDM (DFT-spreading-OFDM), SC-FDE (Single Carrier-Frequency Domain Equalization), etc. can be considered. Also, a forward error correction code may be combined.
　本実施例に係る各実施例では送信装置１００、受信装置２００ともに、ｎ本のアンテナを用いてｎ空間多重を実現するｎ×ｎのＭＩＭＯを想定したが、特にこれに限らない。ｋ本の送信アンテナ、ｎ本の受信アンテナによるｋ×ｎのＭＩＭＯアンテナ構成にも適用可能であるし、あるいは、ＭＩＭＯの一様態として考えられるＵＣＡアンテナを用いたＯＡＭ無線多重にも適用可能である。 In each embodiment according to the present embodiment, both the transmitting apparatus 100 and the receiving apparatus 200 assume n×n MIMO that implements n spatial multiplexing using n antennas, but the present invention is not particularly limited to this. It can be applied to a k×n MIMO antenna configuration with k transmission antennas and n reception antennas, or it can be applied to OAM radio multiplexing using UCA antennas, which is considered as one aspect of MIMO. .
　ジッタの最大値±ΔＴｘ、±ΔＲｘは、送信装置１００および受信装置２００のアンテナポート間のサンプル同期能力を示すものとしたが、そのほかの要因による影響を加味した値としても良い。たとえば前述のＳＣ－ＦＤＥでは周波数利用効率を高めるために低ロールオフ率のｒａｉｓｅｄ－ｃｏｓｉｎｅ　ｆｉｌｔｅｒを帯域制限フィルタとして組み合わせる場合があるが、時間応答が長いために、後続ＯＦＤＭシンボルからのシンボル間干渉が生じるようなケースでは、ジッタの前方方向の絶対値を大きくとっても良い。 Although the maximum values of jitter ±Δ Tx and ±Δ Rx indicate the sample synchronization capability between the antenna ports of transmitting apparatus 100 and receiving apparatus 200, they may be values that take into account the influence of other factors. For example, in the SC-FDE mentioned above, a raised-cosine filter with a low roll-off rate may be combined as a band-limiting filter in order to increase the frequency utilization efficiency. In such a case, the absolute value of jitter in the forward direction may be increased.
　また、ジッタの最大値±ΔＴｘ（±ΔＲｘ）を制御情報として通知することとしているが、既知の情報として送信装置１００および受信装置２００が予め記憶しておいても良い。 Also, although the maximum jitter value ±Δ Tx (±Δ Rx ) is notified as control information, it may be stored in advance in transmitting apparatus 100 and receiving apparatus 200 as known information.
　（実施例２）
　以下に図面を参照して、実施例２について説明する。実施例２は、各ＭＩＭＯチャンネルに同期信号を多重し、受信装置２００が特定のアンテナポートに対する各アンテナポートの同期ずれ量を直接検出する点が、実施例１と相違する。よって、以下の実施例２の説明では、実施例１との相違点を中心に説明し、実施例１と同様の機能構成を有するものには、実施例１の説明で用いた符号と同様の符号を付与し、その説明を省略する。 (Example 2)
A second embodiment will be described below with reference to the drawings. The second embodiment is different from the first embodiment in that a synchronization signal is multiplexed on each MIMO channel, and the receiving apparatus 200 directly detects the synchronization deviation amount of each antenna port with respect to a specific antenna port. Therefore, in the following description of the second embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
　（実施例２に係る送信装置の構成例）
　図８は、実施例２に係る送信装置の構成例を示す図である。本実施例に係る送信装置１００の各送信回路１２０は、実施例１に係る送信回路１２０から送信側同期能力情報送出回路１２７を削除した構成である。 (Configuration example of transmission device according to embodiment 2)
FIG. 8 is a diagram illustrating a configuration example of a transmission device according to a second embodiment; Each transmission circuit 120 of the transmission device 100 according to the present embodiment has a configuration obtained by removing the transmission side synchronization capability information transmission circuit 127 from the transmission circuit 120 according to the first embodiment.
　本実施例に係る送信装置１００は、各ＭＩＭＯチャンネルにおいて同期信号多重回路１２６から送出される同期信号を無線フレームの先頭に多重する。送信装置１００は、無線フレームごとに同期信号を多重するＭＩＭＯチャンネルを変える時分割処理によって単一の同期信号を各ＭＩＭＯチャンネルで使いまわしても良いし、自己相関特性だけでなく相互相関特性にも優れた複数の同期信号（たとえばＺａｄｏｆｆ－Ｃｈｕ系列を元に生成した変調波）を各ＭＩＭＯチャンネルに空間多重しても良い。 The transmitting apparatus 100 according to this embodiment multiplexes the synchronization signal sent from the synchronization signal multiplexing circuit 126 in each MIMO channel at the beginning of the radio frame. Transmitting apparatus 100 may reuse a single synchronization signal in each MIMO channel by time-division processing that changes the MIMO channel that multiplexes the synchronization signal for each radio frame. A plurality of excellent synchronization signals (for example, modulated waves generated based on Zadoff-Chu sequences) may be spatially multiplexed to each MIMO channel.
　（実施例２に係る受信装置の構成例）
　図９は、実施例２に係る受信装置の構成例を示す図である。 (Configuration example of receiving device according to embodiment 2)
FIG. 9 is a diagram illustrating a configuration example of a receiving apparatus according to the second embodiment;
　本実施例に係る受信装置２００は、各ＭＩＭＯチャンネルの無線フレーム位置検出回路２４３で同定した同期情報から、特定のＭＩＭＯチャンネル（たとえばｃｈ１）に対する各ＭＩＭＯチャンネルのサンプルずれΔｉ(ｉ＝２，…，Ｎ)を算出する。ＦＦＴ区間決定回路２４２は、最も早いタイミングで受信されたＭＩＭＯチャンネルのＣＰｒｅｆｉｘの終点を、各ＭＩＭＯチャンネルのＦＦＴ区間の始点として、そこからＦＦＴサイズ（２０４８ＦＦＴなら２０４８サンプル）相当のサンプル区間をＦＦＴ区間に決定する。ＦＦＴ回路２４６は、決定されたＦＦＴ区間に基づいて、ＦＦＴを行い、サブキャリアに分解する。 The receiving apparatus 200 according to the present embodiment detects the sample shift Δi (i=2, . N) is calculated. The FFT interval determination circuit 242 sets the end point of the CPrefix of the MIMO channel received at the earliest timing as the starting point of the FFT interval of each MIMO channel, and sets a sample interval corresponding to the FFT size (2048 samples for 2048 FFT) as the FFT interval. decide. The FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
　図１０は、実施例２に係るＦＦＴ区間のオフセット方法について説明するための図である。送信装置１００は、各ＭＩＭＯチャンネルに相互相関特性の良好な同期信号を多重する。受信装置２００は、各ＭＩＭＯチャンネルの無線フレームのサンプル位置を前記同期信号により検出する。これによって、最も早着となるＭＩＭＯチャンネルのＣＰｒｅｆｉｘの終点をＦＦＴ区間の始点としてＯＦＤＭ復調することができる。 FIG. 10 is a diagram for explaining the method of offsetting the FFT interval according to the second embodiment. Transmitting apparatus 100 multiplexes synchronization signals with good cross-correlation characteristics onto each MIMO channel. Receiving apparatus 200 detects the sample position of the radio frame of each MIMO channel from the synchronization signal. As a result, OFDM demodulation can be performed with the end point of the CPrefix of the earliest arriving MIMO channel as the start point of the FFT interval.
　（実施例３）
　以下に図面を参照して、実施例３について説明する。実施例３は、送信装置１００が個別にジッタの最大値を受信装置２００に送信する点が、実施例１と相違する。よって、以下の実施例３の説明では、実施例１との相違点を中心に説明し、実施例１と同様の機能構成を有するものには、実施例１の説明で用いた符号と同様の符号を付与し、その説明を省略する。 (Example 3)
A third embodiment will be described below with reference to the drawings. The third embodiment differs from the first embodiment in that the transmitter 100 individually transmits the maximum value of jitter to the receiver 200 . Therefore, in the following description of the third embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
　本実施例に係る無線通信システムによれば、複数の端末局（送信装置１００の一例）から１台の基地局（受信装置２００の一例）に対する上りリンクマルチユーザＭＩＭＯに対応することができる。 According to the radio communication system according to the present embodiment, it is possible to support uplink multi-user MIMO from a plurality of terminal stations (an example of the transmitting device 100) to a single base station (an example of the receiving device 200).
　図１１は、上りリンクマルチユーザＭＩＭＯにおけるＦＦＴ区間のオフセット方法について説明するための図である。セルラ型無線通信システムにおける上りリンクマルチユーザＭＩＭＯでは、原則下りリンクで同期信号の検出を行う一方で、上りリンクの同期実現のためには伝送遅延を考慮した送信タイミング制御を行うが、前述の通りアンテナポート間のサンプルレベルの同期が困難となる可能性はある。さらに、ユーザ毎に端末設計が異なるとアンテナポート間ジッタΔＴｘもユーザ毎に異なる値ΔＴｘ＿ＵＥｉを持つ可能性がある。 FIG. 11 is a diagram for explaining a method of offsetting FFT intervals in uplink multi-user MIMO. In uplink multi-user MIMO in a cellular radio communication system, in principle, synchronization signals are detected in the downlink, while transmission timing is controlled in consideration of transmission delay in order to achieve uplink synchronization, as described above. Synchronization of sample levels between antenna ports can be difficult. Furthermore, if the terminal design differs for each user, the inter-antenna port jitter Δ Tx may also have a different value Δ Tx_UEi for each user.
　そこで、送信装置１００および受信装置２００は、非ＭＩＭＯ通信時の制御チャネルなどを用いて、ΔＴｘ＿ＵＥｉを示す情報を共有する。 Therefore, transmitting apparatus 100 and receiving apparatus 200 share information indicating ΔTx_UEi using a control channel or the like during non-MIMO communication.
　図１２は、実施例３に係る無線通信システムの構成例を示す図である。前提として、能力の異なる無線機（送信装置１００の一例）が混在する場合、無線機によってアンテナポート間のサンプルずれ量（ジッタの大きさ）が異なることが考えられる。そこで、各端末局（送信局）（送信装置１００の一例）から基地局（受信局）（受信装置２００の一例）に対し、個別に送信装置１００のアンテナポート間のサンプル同期能力を示すジッタの最大値±ΔＴｘ＿ＵＥｉ（ｉ＝１，…，ｎ）を通知する。なお、セルラ型無線通信システムにおいて同期信号の検出は下りリンクのみで実施し、上りリンクの同期は下りリンクの同期情報を元に送信タイミング制御により確立する設計の場合、上りリンクにおける送信装置１００（端末局）は、同期信号多重回路１２６を備えていなくて良い。 FIG. 12 is a diagram illustrating a configuration example of a wireless communication system according to the third embodiment; As a premise, when radio devices with different capabilities (an example of the transmission device 100) coexist, it is conceivable that the amount of sample deviation (magnitude of jitter) between antenna ports differs depending on the radio device. Therefore, each terminal station (transmitting station) (an example of the transmitting apparatus 100) individually transmits a jitter value indicating the sample synchronization capability between the antenna ports of the transmitting apparatus 100 to the base station (receiving station) (an example of the receiving apparatus 200). Notify the maximum value ±Δ Tx_UEi (i=1, . . . , n). In the case of a design in which the synchronization signal is detected only in the downlink in the cellular radio communication system, and the synchronization of the uplink is established by transmission timing control based on the synchronization information of the downlink, the transmitting apparatus 100 in the uplink ( terminal station) need not include the synchronization signal multiplexing circuit 126 .
　受信装置２００は、ΔＴｘ＿ＵＥｉ（ｉ＝１，…，ｎ）の最大値、すなわちｍａｘ｛ΔＴｘ＿ＵＥｉ（ｉ＝１，…，ｎ）｝＝ΔＭＡＸを導出する。また、受信装置２００自体のアンテナポート間のサンプル同期能力を示すジッタ±ΔＲｘも事前に把握しておく。ＦＦＴ区間決定回路２４２は、特定のＭＩＭＯチャンネル（たとえばｃｈ１）で同定したＣＰｒｅｆｉｘの終点に対し、少なくとも２×（ΔＭＡＸ＋ΔＲｘ）サンプル以上前方を各ＭＩＭＯチャンネルのＦＦＴ区間の始点として、そこからＦＦＴサイズ（２０４８ＦＦＴなら２０４８サンプル）相当のサンプル区間をＦＦＴ区間に決定する。ＦＦＴ回路２４６は、決定されたＦＦＴ区間に基づいて、ＦＦＴを行い、サブキャリアに分解する。 Receiving apparatus 200 derives the maximum value of Δ Tx_UEi (i=1, . . . , n), that is, max{Δ Tx_UEi (i=1, . . . , n)}=Δ MAX . Also, the jitter ±Δ Rx , which indicates the sample synchronization capability between the antenna ports of the receiving apparatus 200 itself, is grasped in advance. The FFT interval determination circuit 242 determines the starting point of the FFT interval of each MIMO channel by at least 2×(Δ MAX +Δ Rx ) samples ahead of the end point of CPrefix identified in a specific MIMO channel (for example, ch1), and performs FFT from there. A sample interval corresponding to the size (2048 samples for 2048 FFT) is determined as the FFT interval. The FFT circuit 246 performs FFT and decomposes into subcarriers based on the determined FFT interval.
　（実施例４）
　以下に図面を参照して、実施例４について説明する。実施例４は、送信装置１００がＣＰｒｅｆｉｘに加えて、ＣｙｃｌｉｃＰｏｓｔｆｉｘ（ＣＰｏｓｔｆｉｘ）の付加も行う点が、実施例１と相違する。よって、以下の実施例４の説明では、実施例１との相違点を中心に説明し、実施例１と同様の機能構成を有するものには、実施例１の説明で用いた符号と同様の符号を付与し、その説明を省略する。 (Example 4)
A fourth embodiment will be described below with reference to the drawings. The fourth embodiment differs from the first embodiment in that the transmitting apparatus 100 adds CyclicPostfix (CPostfix) in addition to CPrefix. Therefore, in the following description of the fourth embodiment, the differences from the first embodiment will be mainly described. Reference numerals are assigned and descriptions thereof are omitted.
　図１３は、実施例４に係る送信装置の構成例を示す図である。本実施例に係る送信装置１００の各送信回路１２０は、実施例１に係る各送信回路１２０の構成のＣｙｃｌｉｃＰｒｅｆｉｘ付加回路１２５に代えて、ＣｙｃｌｉｃＰｒｅｆｉｘ／Ｐｏｓｔｆｉｘ付加回路１２５１を備える。 FIG. 13 is a diagram illustrating a configuration example of a transmission device according to the fourth embodiment. Each transmission circuit 120 of the transmission device 100 according to the present embodiment includes a CyclicPrefix/Postfix addition circuit 1251 instead of the CyclicPrefix addition circuit 125 of the configuration of each transmission circuit 120 according to the first embodiment.
　ＣｙｃｌｉｃＰｒｅｆｉｘ／Ｐｏｓｔｆｉｘ付加回路１２５１は、時間領域データ信号の先頭にＣＰｒｅｆｉｘを連結するのに加えて、時間領域データ信号の最後に巡回ポストフィックス（ＣｙｃｌｉｃＰｏｓｔｆｉｘ）（以下、ＣＰｏｓｔｆｉｘとする）を連結する。ＣｙｃｌｉｃＰｒｅｆｉｘ／Ｐｏｓｔｆｉｘ付加回路１２５１は、受信装置２００から送信装置１００へのフィードバックリンクにおいて、受信装置２００のアンテナポート間のサンプル同期能力を示すジッタの最大値±ΔＲｘを示す情報を取得した上で、ＣＰｏｓｔｆｉｘが２（ΔＴｘ＋ΔＲｘ）サンプル以上となるよう設定または可変制御を行う。 The CyclicPrefix/Postfix addition circuit 1251 concatenates CPrefix to the head of the time domain data signal and concatenates a cyclic postfix (hereinafter referred to as CPostfix) to the end of the time domain data signal. CyclicPrefix/Postfix addition circuit 1251 acquires information indicating the maximum value ±Δ Rx of jitter indicating sample synchronization capability between antenna ports of receiving apparatus 200 in the feedback link from receiving apparatus 200 to transmitting apparatus 100, Setting or variable control is performed so that CPostfix is 2 (Δ Tx +Δ Rx ) samples or more.
　図１４は、実施例４に係るＦＦＴ区間のオフセット方法について説明するための図である。本実施例に係るＦＦＴ区間決定回路２４２は、同期信号により同定したＣＰｒｅｆｉｘの終点をそのままＦＦＴ区間の始点として、そこからＦＦＴサイズ（２０４８ＦＦＴなら２０４８サンプル）相当のサンプル区間をＦＦＴ区間に決定する。ＦＦＴ回路２２１６は、決定されたＦＦＴ区間に基づいて、ＦＦＴを行い、サブキャリアに分解する。 FIG. 14 is a diagram for explaining the method of offsetting the FFT interval according to the fourth embodiment. The FFT interval determining circuit 242 according to the present embodiment uses the end point of the CPrefix identified by the synchronization signal as the starting point of the FFT interval, and determines a sample interval corresponding to the FFT size (2048 samples for 2048 FFT) as the FFT interval. The FFT circuit 2216 performs FFT and decomposes into subcarriers based on the determined FFT interval.
　本実施例ではＣｙｃｌｉｃＰｒｅｆｉｘ／Ｐｏｓｔｆｉｘ付加回路１２５１がＣＰｒｅｆｉｘに加え、ＣＰｏｓｔｆｉｘの付加も行う。これによって、アンテナポート間のサンプルずれのうち、前方オフセットはＣＰｒｅｆｉｘで吸収する一方で、後方オフセットはＣＰｏｓｔｆｉｘで吸収することができる。 In this embodiment, the CyclicPrefix/Postfix adding circuit 1251 adds CPostfix in addition to CPrefix. As a result, of the sample shift between antenna ports, the forward offset can be absorbed by CPrefix, while the backward offset can be absorbed by CPostfix.
　また、本実施例では、受信装置２００は、送信側同期能力情報検出回路２４４が不要である。すなわち、受信装置２００は、送信装置１００のアンテナポート間のサンプル同期能力を示すジッタの最大値±ΔＴｘを示す情報を取得しなくても良い。これは、データ信号に十分な長さのＣＰｏｓｔｆｉｘが付加されていることによって、シンボル間干渉を回避できるためである。 Also, in this embodiment, the receiver 200 does not require the transmission-side synchronization capability information detection circuit 244 . That is, receiving apparatus 200 does not need to acquire information indicating maximum jitter value ±Δ Tx indicating sample synchronization capability between antenna ports of transmitting apparatus 100 . This is because inter-symbol interference can be avoided by adding a sufficiently long CPostfix to the data signal.
　なお、実施例１から実施例４は適宜組み合わせても良い。例えば、実施例１と実施例４とを組み合わせても良い。 Note that Embodiments 1 to 4 may be combined as appropriate. For example, the first embodiment and the fourth embodiment may be combined.
　この場合、送信装置１００は、送信装置１００のアンテナポート間のサンプル同期能力を示すジッタ±ΔＴｘによるシンボル間干渉を回避するため、少なくとも２ΔＴｘサンプルのＣＰｏｓｔｆｉｘを付加する。一方、受信装置２００は、受信装置２００のアンテナポート間のサンプル同期能力を示すジッタ±ΔＲｘによるシンボル間干渉を回避するため、同期信号を検出する特定のＭＩＭＯチャンネルにおいて、同定したＣＰｒｅｆｉｘの終点より少なくとも２ΔＲｘサンプル前方のサンプル点をＦＦＴ区間の始点とし、ＯＦＤＭ復調する。 In this case, transmitting apparatus 100 adds CPostfix of at least 2ΔTx samples to avoid inter-symbol interference due to jitter ± ΔTx , which indicates sample synchronization capability between antenna ports of transmitting apparatus 100 . On the other hand, in order to avoid inter-symbol interference due to jitter ± ΔRx , which indicates the sample synchronization capability between antenna ports of receiving apparatus 200, receiving apparatus 200 detects the synchronization signal from the end point of the identified CPrefix in a specific MIMO channel. A sample point at least 2Δ Rx samples ahead is taken as the starting point of the FFT interval and OFDM demodulated.
　これによって、受信装置２００から送信装置１００へのフィードバックリンクで±ΔＲｘを示す情報を通知する処理が不要となる。なお、これはΔＲｘよりもＣＰｒｅｆｉｘのサンプル長が十分長いことを前提としている。 This eliminates the need for the process of notifying the information indicating ±Δ Rx in the feedback link from the receiving device 200 to the transmitting device 100 . Note that this assumes that the sample length of CPrefix is sufficiently longer than ΔRx.
　（実施の形態のまとめ）
　本明細書には、少なくとも下記の各項に記載した無線通信システムおよび通信方法が記載されている。
（第１項）
　送信装置と受信装置とを備え、ＭＩＭＯ通信を行う無線通信システムであって、
　前記送信装置は、無線通信の信号を前記受信装置に送信し、
　前記受信装置は、前記送信装置のアンテナポート間のサンプル同期能力を示すジッタの最大値を示す情報を取得して、前記送信装置の前記ジッタの最大値と、前記受信装置の前記ジッタの最大値とに基づいて、前記送信装置から送信された前記信号の復調または信号等化に用いるＦＦＴ区間を決定する、
　無線通信システム。
（第２項）
　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、
　前記受信装置は、前記送信装置の前記ジッタの最大値ΔＴｘと、前記受信装置の前記ジッタの最大値ΔＲｘとに基づいて、前記同期信号により同定された巡回プレフィックスの終点から少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上前方の前記巡回プレフィックスのサンプル点を前記ＦＦＴ区間の始点とする、
　第１項に記載の無線通信システム。
（第３項）
　前記送信装置は、前記受信装置から前記受信装置のジッタの最大値ΔＲｘを示す情報を取得して、前記巡回プレフィックスの長さを少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上とする、
　第２項に記載の無線通信システム。
（第４項）
　前記送信装置は、前記信号の無線フレームにおいて、各ＭＩＭＯチャンネルに同期信号を多重し、前記各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、
　前記受信装置は、前記各ＭＩＭＯチャンネルの無線フレームのサンプル位置を前記同期信号により検出し、最も早着となるＭＩＭＯチャンネルの前記巡回プレフィックスの終点を前記ＦＦＴ区間の始点とする、
　第１項から第３項のいずれか１項に記載の無線通信システム。
（第５項）
　前記無線通信システムは、複数の送信装置を備え、
　前記複数の送信装置のそれぞれは、前記信号の無線フレームにおいて、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、前記ジッタの最大値を示す情報を前記受信装置に送信し、
　前記受信装置は、前記複数の送信装置のそれぞれから前記ジッタの最大値を示す情報を受信して、受信したそれぞれの送信装置の前記ジッタの最大値ΔＭＡＸを導出し、前記受信装置の前記ジッタの最大値ΔＲｘに基づいて、前記巡回プレフィックスの終点から少なくとも２×（ΔＭＡＸ＋ΔＲｘ）サンプル以上前方を前記ＦＦＴ区間の始点とする、
　第１項から第４項のいずれか１項に記載の無線通信システム。
（第６項）
　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスおよび巡回ポストフィックスを付加し、
　前記受信装置は、前記同期信号により同定された前記巡回プレフィックスの終点を前記ＦＦＴ区間の始点とする、
　第１項から第４項のいずれか１項に記載の無線通信システム。
（第７項）
　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、前記送信装置の前記ジッタの最大値ΔＴｘに基づいて、少なくとも２×ΔＴｘサンプル以上の長さの巡回ポストフィックスを付加し、
　前記受信装置は、前記同期信号により同定された前記巡回プレフィックスの終点から少なくとも２×ΔＲｘサンプル以上前方を前記ＦＦＴ区間の始点とする、
　第１項から第４項のいずれか１項に記載の無線通信システム。
（第８項）
　送信装置と受信装置とを備える無線通信システムにおける通信方法であって、
　前記送信装置が、無線通信の信号を前記受信装置に送信するステップと、
　前記受信装置が、前記送信装置のアンテナポート間のサンプル同期能力を示すジッタの最大値を示す情報を取得して、前記送信装置の前記ジッタの最大値と、前記受信装置の前記ジッタの最大値とに基づいて、前記送信装置から送信された前記信号の復調または信号等化に用いるＦＦＴ区間を決定するステップと、を備える、
　通信方法。 (Summary of embodiment)
Described herein are wireless communication systems and communication methods as set forth in at least the following sections.
(Section 1)
A wireless communication system comprising a transmitting device and a receiving device and performing MIMO communication,
The transmitting device transmits a wireless communication signal to the receiving device,
The receiving device obtains information indicating a maximum value of jitter indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. Based on and, determining the FFT interval used for demodulation or signal equalization of the signal transmitted from the transmitting device,
wireless communication system.
(Section 2)
The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel,
At least 2 (ΔTx+ΔRx) samples from the end point of the cyclic prefix identified by the synchronization signal, based on the maximum jitter value ΔTx of the transmitting device and the maximum jitter value ΔRx of the receiving device. The sample point of the cyclic prefix above is the starting point of the FFT interval,
A wireless communication system according to claim 1.
(Section 3)
The transmitting device acquires information indicating a maximum jitter value ΔRx of the receiving device from the receiving device, and sets the length of the cyclic prefix to at least 2 (ΔTx + ΔRx) samples or more.
3. The wireless communication system according to item 2.
(Section 4)
The transmitting device multiplexes a synchronization signal on each MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel,
The receiving device detects the sample position of the radio frame of each MIMO channel from the synchronization signal, and sets the end point of the cyclic prefix of the earliest arriving MIMO channel as the starting point of the FFT interval.
The wireless communication system according to any one of items 1 to 3.
(Section 5)
The wireless communication system comprises a plurality of transmitters,
each of the plurality of transmitting devices adds a cyclic prefix to a data signal of each MIMO channel in a radio frame of the signal, and transmits information indicating the maximum value of the jitter to the receiving device;
The receiving device receives information indicating the maximum value of the jitter from each of the plurality of transmitting devices, derives the maximum value ΔMAX of the jitter of each received transmitting device, and determines the jitter of the receiving device. Based on the maximum value Δ Rx of , the starting point of the FFT interval is at least 2 × (Δ MAX + Δ Rx ) samples ahead from the end point of the cyclic prefix.
5. The wireless communication system according to any one of items 1 to 4.
(Section 6)
The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix and a cyclic postfix to the data signal of each MIMO channel,
The receiving device sets the end point of the cyclic prefix identified by the synchronization signal as the starting point of the FFT interval,
5. The wireless communication system according to any one of items 1 to 4.
(Section 7)
The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel, and based on the maximum value ΔTx of the jitter of the transmitting device , appending a cyclic postfix of length at least 2×ΔTx samples, and
The receiving device sets the starting point of the FFT interval to be at least 2×ΔRx samples or more ahead from the end point of the cyclic prefix identified by the synchronization signal.
5. The wireless communication system according to any one of items 1 to 4.
(Section 8)
A communication method in a wireless communication system comprising a transmitting device and a receiving device,
the transmitting device transmitting a wireless communication signal to the receiving device;
The receiving device acquires information indicating a maximum jitter value indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. and determining an FFT interval to be used for demodulation or signal equalization of the signal transmitted from the transmitting device, based on
Communication method.
　以上、本実施の形態について説明したが、本発明はかかる特定の実施形態に限定されるものではなく、特許請求の範囲に記載された本発明の要旨の範囲内において、種々の変形・変更が可能である。 Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It is possible.
１００　送信装置
１１０　ビット分配回路
１２０　送信回路
１２１　伝送路推定用信号付加回路
１２２　ｍ－ＱＡＭ変調回路
１２３　周波数多重回路
１２４　ＩＦＦＴ回路
１２５　ＣｙｃｌｉｃＰｒｅｆｉｘ付加回路
１２５１　ＣｙｃｌｉｃＰｒｅｆｉｘ／Ｐｏｓｔｆｉｘ付加回路
１２６　同期信号多重回路
１２７　送信側同期能力情報送出回路
１２８　無線フレーム構成回路
１２９　周波数変換回路
２００　受信装置
２１０　ビット混合回路
２２０　ｍ－ＱＡＭ復調回路
２３０　ＭＩＭＯ等化回路
２４０　受信回路
２４１　伝送路推定用信号検出回路
２４２　ＦＦＴ区間決定回路
２４３　無線フレーム位置検出回路
２４４　送信側同期能力情報検出回路
２４５　同期信号検出回路
２４６　ＦＦＴ回路
２４７　周波数多重分離回路 100 transmission device 110 bit distribution circuit 120 transmission circuit 121 transmission path estimation signal adding circuit 122 m-QAM modulation circuit 123 frequency multiplexing circuit 124 IFFT circuit 125 Cyclic Prefix adding circuit 1251 Cyclic Prefix/Postfix adding circuit 126 synchronous signal multiplexing circuit 127 transmitting side synchronization capability information transmission circuit 128 radio frame configuration circuit 129 frequency conversion circuit 200 receiver 210 bit mixing circuit 220 m-QAM demodulation circuit 230 MIMO equalization circuit 240 reception circuit 241 transmission path estimation signal detection circuit 242 FFT section determination circuit 243 radio frame Position detection circuit 244 Transmission side synchronization capability information detection circuit 245 Synchronization signal detection circuit 246 FFT circuit 247 Frequency demultiplexing circuit

Claims (8)

  1. 　送信装置と受信装置とを備え、ＭＩＭＯ通信を行う無線通信システムであって、
    　前記送信装置は、無線通信の信号を前記受信装置に送信し、
    　前記受信装置は、前記送信装置のアンテナポート間のサンプル同期能力を示すジッタの最大値を示す情報を取得して、前記送信装置の前記ジッタの最大値と、前記受信装置の前記ジッタの最大値とに基づいて、前記送信装置から送信された前記信号の復調または信号等化に用いるＦＦＴ区間を決定する、
    　無線通信システム。     A wireless communication system comprising a transmitting device and a receiving device and performing MIMO communication,
    The transmitting device transmits a wireless communication signal to the receiving device,
    The receiving device obtains information indicating a maximum value of jitter indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. Based on and, determining the FFT interval used for demodulation or signal equalization of the signal transmitted from the transmitting device,
    wireless communication system.
  2. 　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、
    　前記受信装置は、前記送信装置の前記ジッタの最大値ΔＴｘと、前記受信装置の前記ジッタの最大値ΔＲｘとに基づいて、前記同期信号により同定された巡回プレフィックスの終点から少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上前方の前記巡回プレフィックスのサンプル点を前記ＦＦＴ区間の始点とする、
    　請求項１に記載の無線通信システム。     The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel,
    Based on the maximum jitter value ΔTx of the transmitting device and the maximum jitter value ΔRx of the receiving device, the receiving device receives at least 2 (Δ Tx + Δ Rx ) samples or more before the sample point of the cyclic prefix is set as the starting point of the FFT interval;
    A wireless communication system according to claim 1 .
  3. 　前記送信装置は、前記受信装置から前記受信装置のジッタの最大値ΔＲｘを示す情報を取得して、前記巡回プレフィックスの長さを少なくとも２(ΔＴｘ＋ΔＲｘ)サンプル以上とする、
    　請求項２に記載の無線通信システム。     The transmitting device acquires information indicating the maximum jitter value Δ Rx of the receiving device from the receiving device, and sets the length of the cyclic prefix to at least 2 (Δ Tx + Δ Rx ) samples or more.
    A wireless communication system according to claim 2.
  4. 　前記送信装置は、前記信号の無線フレームにおいて、各ＭＩＭＯチャンネルに同期信号を多重し、前記各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、
    　前記受信装置は、前記各ＭＩＭＯチャンネルの無線フレームのサンプル位置を前記同期信号により検出し、最も早着となるＭＩＭＯチャンネルの前記巡回プレフィックスの終点を前記ＦＦＴ区間の始点とする、
    　請求項１から３のいずれか１項に記載の無線通信システム。     The transmitting device multiplexes a synchronization signal on each MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel,
    The receiving device detects the sample position of the radio frame of each MIMO channel from the synchronization signal, and sets the end point of the cyclic prefix of the earliest arriving MIMO channel as the starting point of the FFT interval.
    The radio communication system according to any one of claims 1 to 3.
  5. 　前記無線通信システムは、複数の送信装置を備え、
    　前記複数の送信装置のそれぞれは、前記信号の無線フレームにおいて、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、前記ジッタの最大値を示す情報を前記受信装置に送信し、
    　前記受信装置は、前記複数の送信装置のそれぞれから前記ジッタの最大値を示す情報を受信して、受信したそれぞれの送信装置の前記ジッタの最大値ΔＭＡＸを導出し、前記受信装置の前記ジッタの最大値ΔＲｘに基づいて、前記巡回プレフィックスの終点から少なくとも２×（ΔＭＡＸ＋ΔＲｘ）サンプル以上前方を前記ＦＦＴ区間の始点とする、
    　請求項１から４のいずれか１項に記載の無線通信システム。     The wireless communication system comprises a plurality of transmitters,
    each of the plurality of transmitting devices adds a cyclic prefix to a data signal of each MIMO channel in a radio frame of the signal, and transmits information indicating the maximum value of the jitter to the receiving device;
    The receiving device receives information indicating the maximum value of the jitter from each of the plurality of transmitting devices, derives the maximum value ΔMAX of the jitter of each received transmitting device, and determines the jitter of the receiving device. Based on the maximum value Δ Rx of , the starting point of the FFT interval is at least 2 × (Δ MAX + Δ Rx ) samples ahead from the end point of the cyclic prefix.
    A radio communication system according to any one of claims 1 to 4.
  6. 　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスおよび巡回ポストフィックスを付加し、
    　前記受信装置は、前記同期信号により同定された前記巡回プレフィックスの終点を前記ＦＦＴ区間の始点とする、
    　請求項１から４のいずれか１項に記載の無線通信システム。     The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix and a cyclic postfix to the data signal of each MIMO channel,
    The receiving device sets the end point of the cyclic prefix identified by the synchronization signal as the starting point of the FFT interval,
    A radio communication system according to any one of claims 1 to 4.
  7. 　前記送信装置は、前記信号の無線フレームにおいて、特定のＭＩＭＯチャンネルに同期信号を多重して、各ＭＩＭＯチャンネルのデータ信号に巡回プレフィックスを付加し、前記送信装置の前記ジッタの最大値ΔＴｘに基づいて、少なくとも２×ΔＴｘサンプル以上の長さの巡回ポストフィックスを付加し、
    　前記受信装置は、前記同期信号により同定された前記巡回プレフィックスの終点から少なくとも２×ΔＲｘサンプル以上前方を前記ＦＦＴ区間の始点とする、
    　請求項１から４のいずれか１項に記載の無線通信システム。     The transmitting device multiplexes a synchronization signal on a specific MIMO channel in a radio frame of the signal, adds a cyclic prefix to the data signal of each MIMO channel, and based on the maximum value ΔTx of the jitter of the transmitting device appending a cyclic postfix of length at least 2×Δ Tx samples or longer,
    The receiving device sets the starting point of the FFT interval to be at least 2× ΔRx samples ahead from the end point of the cyclic prefix identified by the synchronization signal.
    A radio communication system according to any one of claims 1 to 4.
  8. 　送信装置と受信装置とを備える無線通信システムにおける通信方法であって、
    　前記送信装置が、無線通信の信号を前記受信装置に送信するステップと、
    　前記受信装置が、前記送信装置のアンテナポート間のサンプル同期能力を示すジッタの最大値を示す情報を取得して、前記送信装置の前記ジッタの最大値と、前記受信装置の前記ジッタの最大値とに基づいて、前記送信装置から送信された前記信号の復調または信号等化に用いるＦＦＴ区間を決定するステップと、を備える、
    　通信方法。     A communication method in a wireless communication system comprising a transmitting device and a receiving device,
    the transmitting device transmitting a wireless communication signal to the receiving device;
    The receiving device acquires information indicating a maximum jitter value indicating sample synchronization capability between antenna ports of the transmitting device, and obtains the maximum jitter value of the transmitting device and the maximum jitter value of the receiving device. and determining an FFT interval to be used for demodulation or signal equalization of the signal transmitted from the transmitting device, based on
    Communication method.
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