WO2017037861A1 - Station de base, terminal, système de communication sans fil, et procédé de communication sans fil - Google Patents

Station de base, terminal, système de communication sans fil, et procédé de communication sans fil Download PDF

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Publication number
WO2017037861A1
WO2017037861A1 PCT/JP2015/074815 JP2015074815W WO2017037861A1 WO 2017037861 A1 WO2017037861 A1 WO 2017037861A1 JP 2015074815 W JP2015074815 W JP 2015074815W WO 2017037861 A1 WO2017037861 A1 WO 2017037861A1
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user data
base station
terminal
terminals
transmitted
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PCT/JP2015/074815
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English (en)
Japanese (ja)
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崇志 瀬山
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富士通株式会社
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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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes

Definitions

  • the present invention relates to a base station, a terminal, a wireless communication system, and a wireless communication method for performing wireless communication between a base station and a terminal.
  • LTE Long Term Evolution
  • 3GPP Third Generation Partnership Project
  • An Orthogonal Multiple Access (OMA) method is used for LTE downlink.
  • OFDMA Orthogonal Multiplexing
  • OFDMA Orthogonal Frequency Division Multiple Access
  • FIG. 12 is a diagram for explaining orthogonal multiplexing and non-orthogonal multiplexing.
  • the horizontal axis is frequency and the vertical axis is power.
  • OFDMA of FIG. 12A when data is scheduled to a plurality of users (terminals UE # 1, # 2), orthogonal subbands that do not interfere with each other are allocated in the same time zone.
  • a non-orthogonal multiple access NOMA (Non-Orthogonal Multiple Access) system is being studied that allocates non-orthogonal resources that interfere with each other to a plurality of users.
  • NOMA NOMA
  • SIC Successessive Interference Canceller
  • demodulates and decodes a signal intended for the user terminal after canceling a signal intended for another user has been proposed (for example, see Non-Patent Document 1 below).
  • a user cancels a signal for other users that causes interference that is simultaneously multiplexed on the same resource.
  • two users are allocated with a predetermined power distribution in the same subband.
  • a user 1 with a high SNR near the base station and a user 2 with a low SNR far from the base station are selected. Since the SNR of the user 2 is lower than the SNR of the user 1, the modulation coding rate (MCS: Modulation and channel coding scheme) of the signal for the user 2 is also low. Thereby, the user 1 succeeds in demodulating / decoding the signal for the user 2 with high probability.
  • the user 1 can cancel the influence of the interference from the signal for the user 2 by canceling the signal for the user 2 which has been successfully decoded from the received signal by the SIC. On the other hand, the signal of user 1 becomes interference for user 2.
  • FIG. 13 is a chart showing the capacity of orthogonal multiplexing and non-orthogonal multiplexing. Since the SNR of the user 2 is low and the influence by other interference noise is large, the influence by the interference of the signal of the user 1 is small.
  • the horizontal axis represents the capacity of user 1 and the vertical axis represents the capacity of user 2. It can be seen that NOMA is always located in the upper right region from OMA, and the performance is improved.
  • a technique in which NOMA is applied to Multi-User MIMO is disclosed (for example, see Patent Document 1 and Non-Patent Document 2 below).
  • a base station forms a plurality of beams by a plurality of antennas, and multiplexes users non-orthogonally using NOMA in each beam.
  • a technique having a NOMA / SU-MIMO mode for non-orthogonal multiplexing of Single User MIMO (SU-MIMO) users is disclosed (for example, the following patents) Reference 2).
  • SU-MIMO Single User MIMO
  • JP 2014-131202 A Japanese Patent Application Laid-Open No. 2014-154962
  • PF Utility Proportional Fairness Utility
  • the power between the beams is only considered to be evenly distributed, and more efficient resource allocation cannot be performed, and the PF Utility cannot be increased.
  • an object of the present invention is to improve fairness of wireless communication between users by non-orthogonal multiplexing of MIMO and transmission diversity.
  • a controller that spatially multiplexes a plurality of user data to be transmitted to a plurality of terminals, and further non-orthogonally multiplexes the user data to be transmitted to other terminals.
  • MIMO and transmission diversity can be non-orthogonal multiplexed, and the fairness of wireless communication between users can be improved.
  • FIG. 1 is an explanatory diagram of non-orthogonal multiplexing of MIMO and transmission diversity according to the embodiment.
  • FIG. 2 is a diagram of an internal configuration of the base station according to the first embodiment.
  • FIG. 3 is a diagram illustrating an internal configuration of the terminal according to the first embodiment.
  • FIG. 4 is a diagram of a hardware configuration example of the base station according to the first embodiment.
  • FIG. 5 is a diagram of a hardware configuration example of the terminal according to the first embodiment.
  • FIG. 6 is a flowchart of an example of CSI calculation processing in the terminal according to the first embodiment.
  • FIG. 7 is a flowchart of an example of scheduling in the base station according to the first embodiment.
  • FIG. 1 is an explanatory diagram of non-orthogonal multiplexing of MIMO and transmission diversity according to the embodiment.
  • FIG. 2 is a diagram of an internal configuration of the base station according to the first embodiment.
  • FIG. 3 is a diagram illustrating an internal configuration of the terminal according to the
  • FIG. 8 is a flowchart of an example of CSI calculation processing in the terminal according to the second embodiment.
  • FIG. 9 is a diagram of an internal configuration of the base station according to the third embodiment.
  • FIG. 10 is a flowchart of an example of CSI calculation processing in the terminal according to the fifth embodiment.
  • FIG. 11 is a flowchart of an example of scheduling in the base station according to the fifth embodiment.
  • FIG. 12 is a diagram for explaining orthogonal multiplexing and non-orthogonal multiplexing.
  • FIG. 13 is a chart showing the capacity of orthogonal multiplexing and non-orthogonal multiplexing.
  • a H represents a complex transposed matrix of matrix A
  • a H represents a complex transposed vector of vector a.
  • E ⁇ A ⁇ represents an average of A
  • I N represents an N ⁇ N unit matrix.
  • O N represents an N ⁇ N matrix in which all components are zero.
  • diag (a 1, a 2, ... a N) represents a 1, a 2, ... diagonal matrix with a N diagonal elements.
  • FIG. 1 is an explanatory diagram of non-orthogonal multiplexing of MIMO and transmission diversity according to the embodiment.
  • the base station BS (100) performs radio communication using the beam 1 with the terminal UE # 1 (101) by beam forming using a plurality of antennas 110.
  • the base station BS (100) performs radio communication with the beam 2 different from the beam 1 between the terminal UE # 1 and the terminal UE # 2 (101) having a different in-cell position.
  • terminals UE # 1 and # 2 (101) are located close to the base station BS (100), and the base station BS (100) is in the reach range (cell range) of the beams 1 and 2 by NOMA. Of these, wireless communication is also performed with terminals UE (# 3, # 4) located far from the base station BS.
  • the plurality of beams (beams 1 and 2) are used to perform wireless communication with another terminal UE (terminal UE # 5 in the illustrated example).
  • This terminal UE # 5 does not use another new beam different from the beams 1 and 2, but uses the beams 1 and 2 used for the terminals UE # 1 and # 2.
  • the terminal UE # 5 (101) is assumed to be rank 1 (Rank-1), and the terminal UE # 1, 2 (101) is assumed to be rank 2 (Rank-2).
  • Terminal UE # 5 (101) is located away from base station (BS) 100, and applies transmission diversity.
  • Terminals UE # 1, 2 (101) are located near base station (BS) 100 and apply MU-MIMO.
  • the base station 100 then performs a non-orthogonal multiplexing (transmission diversity with MU-MIMO) on the Rank-1 terminal UE # 5 (101) and the Rank-2 terminals UE # 1 and # 2 (101). Wireless communication with non-orthogonal multiplexing).
  • the Rank-2 terminal 101 may be UE # 1 to # 4.
  • a user (UE # 5) that does not perform SIC generally has low reception quality (for example, SNR). Therefore, non-orthogonal multiplexing is performed between MU-MIMO users (UE # 1, # 2) and transmission diversity users (UE # 5).
  • PF Utility Proportional Fairness Utility
  • the power between the beams 1 and 2 is changed in consideration of the fairness between users, thereby further increasing the PF Utility.
  • FIG. 2 is a diagram of an internal configuration of the base station according to the first embodiment.
  • Base station (BS) 100 includes a downlink processing unit 201 that transmits information to terminal 101 and an uplink processing unit 202 that receives and transmits information transmitted from terminal 101.
  • the Downlink processing unit 201 has a number of transmission systems corresponding to the number of transmission beams (two systems in the illustrated example).
  • the downlink processing unit 201 of each system includes a plurality of user data generation units 211 for each user data (terminal 101), a non-orthogonal multiplexing unit 212, a beam power adjustment unit 213, a precoding unit 214, a channel And a multiplexing unit 215. Further, IFFT section 216, CP adding section 217, Downlink radio processing section 218, and antenna 219 are included.
  • the user data generation unit 211 includes a plurality (B) of user data generation units 211a and the number of user data (number of terminals, for example, UE # 5) that is non-orthogonal-multiplexed with the user data generated by the user data generation unit 211a. 1) user data generation unit 211b.
  • a plurality of user data generation units 211 (211a, 211b) to which user data to be transmitted to transmission destination users (for example, terminals UE # 1 to # 5) is input are selectively activated.
  • Each user data generation unit 211 (211a, 211b) includes an error correction encoding unit 221, a modulation unit 222, and a power adjustment unit 223.
  • the plurality of user data generation units 211 generate user data for each user specified by the scheduler unit 231.
  • the error correction coding unit 221 performs error correction coding on the input user data for each user at the coding rate for the corresponding user instructed from the scheduler unit 231.
  • the modulation unit 222 modulates user data using the modulation method instructed by the scheduler unit 231.
  • the power adjustment unit 223 performs adjustment so that the power for the corresponding user instructed from the scheduler unit 231 is obtained.
  • the non-orthogonal multiplexing unit 212 performs non-orthogonal multiplexing of B user data output from the user data generation unit 211a and one user data output from the user data generation unit 211b under the control of the scheduler unit 231. Do.
  • the two non-orthogonal multiplexing units 212 in FIG. 2 are described corresponding to the items in the formula of formula (1) described later, the number can be reduced to one.
  • the precoding unit 214 multiplies the input signal by the precoding matrix determined by the scheduler unit 231 to form a beam.
  • a precoding vector having the number of rows equal to the number of spatially multiplexed beams is applied to non-orthogonal multiplexed user data.
  • the beam power adjustment unit 213 adjusts the power of the beam after non-orthogonal multiplexing so that the power instructed by the scheduler unit 231 is obtained.
  • the Downlink control signal generation unit 232 generates control signals such as MCS and power for each user.
  • the channel multiplexer 215 multiplexes user data and control signals that have been subjected to non-orthogonal multiplexing.
  • the IFFT unit 216 performs inverse fast Fourier transform to convert it into an effective symbol.
  • CP adding section 217 adds CP (Cyclic Prefix) to the effective symbol to generate an OFDM symbol.
  • the Downlink radio processing unit 218 performs up-conversion (Up conversion) and DA conversion on the radio frequency of the OFDM symbol, and transmits radio waves from the antenna 219 toward the terminal (101).
  • the scheduler unit 231 transmits a transmission beam (a precoding matrix to be applied), a user who assigns each beam within a single beam (a plurality of users in the case of non-orthogonal multiplexing), the power of each user, Determine power and MCS for each user. Details of the scheduler unit 231 will be described later.
  • the Uplink processing unit 202 includes an antenna 241, an Uplink wireless processing unit 242, an Uplink control information extraction unit 243, and the like.
  • the Uplink wireless processing unit 242 receives a wireless signal transmitted from the terminal 101 through the antenna 241 and performs down conversion and AD conversion.
  • the Uplink control information extraction unit 243 extracts channel state information such as Ack / Nack and CQI / PMI / RI included in the Uplink signal.
  • FIG. 3 is a diagram illustrating an internal configuration of the terminal according to the first embodiment.
  • the terminal (UE) 101 includes a Downlink processing unit 301 that receives and processes information transmitted from the base station 100, and an Uplink processing unit 302 that transmits information to the base station 100.
  • the downlink processing unit 301 has a number of reception systems corresponding to the number of antennas (two systems in the illustrated example).
  • the downlink processing unit 301 of each system includes an antenna 311, a downlink radio processing unit 312, a CP removal unit 313, an FFT unit 314, and a channel demapping unit 315.
  • the Downlink radio processing unit 312 performs down conversion and AD conversion of radio waves received via the antenna 311 into radio frequency baseband signals.
  • CP removing section 313 removes the CP from the received OFDM symbol and obtains an effective symbol.
  • the FFT unit 314 performs a fast Fourier transform of the effective symbol and converts it to a frequency domain signal.
  • the CSI estimating unit 321 is connected to the channel demapping unit 315 of the Downlink processing unit 301 of each system, and estimates channel quality information (CSI) of each system with reference to feedback information transmitted from the terminal 101. Details of the CSI estimation unit 321 will be described later.
  • the Downlink processing unit 301 of one system further includes a spatial filter unit 316, a cancellation unit 317, a demodulation unit 318, an error correction decoding unit 319, and an Ack / Nack generation unit 320.
  • the spatial filter unit 316 is connected to the channel demapping unit 315 and performs, for example, the MMSE method to separate the beam addressed to the own terminal 101.
  • a beam including a data signal addressed to its own terminal 101 when another terminal 101 of MCS lower than the MCS of its own terminal 101 is non-orthogonally multiplexed in the beam, the non-orthogonal multiplexed terminal 101 having the lowest MCS is included.
  • the demodulator 318 performs demodulation from the lowest to the highest MCS.
  • the cancel unit 317 cancels non-orthogonal multiplexed user data (user data of another terminal 101) from the received signal, and the error correction decoding unit 319 performs error correction decoding of the data signal for the own terminal 101.
  • the Ack / Nack generation unit 320 generates an Ack signal when the error correction decoding of the user data for the own terminal 101 succeeds, and generates a Nack signal when the user data fails.
  • the Downlink processing unit 301 of the other system further includes a Downlink control signal demodulation / decoding unit 322.
  • the Downlink control signal demodulation / decoding unit 322 is connected to the channel demapping unit 315, demodulates and decodes the Downlink control signal, and extracts MCS and power information for each user data included in the Downlink control signal.
  • the Downlink control signal demodulation / decoding unit 322 outputs the Downlink control signal to the spatial filter unit 316 and the cancellation unit 317 of one system.
  • the Uplink transmission unit 331 of the Uplink processing unit 302 performs error correction coding and modulation of Uplink user data, Ack / Nack signals, and CSI.
  • the Uplink wireless processing unit 332 performs DA conversion of transmission data, up-conversion to a radio frequency, and the like, and wirelessly transmits from the antenna 333 to the base station 100.
  • FIG. 4 is a diagram of a hardware configuration example of the base station according to the first embodiment.
  • the base station 100 includes a processor 401, a storage device 402, an LSI 403, a wireless processing circuit 404, and a network interface (NIF) circuit 405.
  • NIF network interface
  • a CPU or the like is used for the processor 401 and controls the entire base station 100.
  • the storage device 402 stores a program executed by the processor 401 using a memory or the like, and stores data when the program is executed.
  • the LSI 403 is a control unit that controls transmission / reception of user data, and executes the functions of the user data generation unit 211 to the CP addition unit 217, the scheduler unit 231, and the Downlink control signal generation unit 232 in FIG.
  • the processor 401 may perform data processing for transmission / reception in cooperation with the LSI 403.
  • the wireless processing circuit 404 performs wireless communication with the terminal 101 via the antennas 219 and 241 and corresponds to the Downlink wireless processing unit 218 and the Uplink wireless processing unit 242 in FIG.
  • the NIF circuit 405 is a wired interface that transmits and receives data and control signals to and from the terminal 101 to and from the core network and other base stations 100.
  • the base station 100 may be configured such that the radio processing circuit 404 and the antennas 219 and 241 are separated as RRH (Remote Radio Head) 410.
  • RRH Remote Radio Head
  • FIG. 5 is a diagram of a hardware configuration example of the terminal according to the first embodiment. As illustrated in FIG. 5, the terminal 101 includes a processor 501, a storage device 502, an LSI 503, and a wireless processing circuit 504.
  • a CPU or the like is used for the processor 501 and controls the entire terminal 101.
  • the storage device 502 stores a program executed by the processor 501 using a memory or the like, and stores data when the program is executed.
  • the LSI 503 is a control unit that controls transmission / reception of user data, and executes the functions of the CP removal unit 313 to the Downlink control signal demodulation / decoding unit 322 in FIG.
  • the processor 501 may perform data processing related to transmission / reception in cooperation with the LSI 503.
  • the wireless processing circuit 504 performs wireless communication with the base station 100 via the antennas 311 and 333, and corresponds to the Downlink wireless processing unit 312 and the Uplink wireless processing unit 332 in FIG.
  • the number of transmission antennas of the base station 100 is N tx
  • the number of reception antennas of the terminal 101 is N rx .
  • User data of B users (terminal 101, for example, UE # 1 to # 4) is multiplexed with a beam
  • user data of B + 1th user (for example, UE # 5, Rank-1) is further multiplexed by non-orthogonal multiplexing.
  • the transmission signal vector of N tx is expressed by the following equation (1).
  • V is an N tx ⁇ B precoding matrix
  • x is a B ⁇ 1 signal vector
  • p is transmission power allocated to x
  • a is a B ⁇ 1 precoding matrix
  • x B + 1 is a 1 ⁇ 1 signal.
  • the vector q represents the transmission power assigned to x B + 1 .
  • the received signal of the kth user is It can be expressed.
  • y k is an N rx received signal vector
  • H k is an N rx ⁇ N tx channel matrix
  • n k is an N rx ⁇ 1 noise vector
  • the demodulated SNR when demodulating the b-th layer of x is the weight vector of the spatial filter for the b-th layer of x. If w H k, b , It becomes.
  • the CSI estimation unit of the k-th user terminal calculates each piece of information shown in the following equation (12) and feeds it back to the base station 100 as CSI.
  • ⁇ k, i can be considered as interference from x to x B + 1 .
  • ⁇ k, b, s is the normalized signal power of the b-th beam when only x is transmitted, and ⁇ k, b, i is the b-th beam other than the b-th beam when only x is transmitted. It can be regarded as the normalized interference power given to the beam.
  • ⁇ k, b, s and ⁇ k, b, i may be fed back to the base station 100 for all beams, or only for a plurality of beams having good SNR k, b in order to reduce the amount of feedback information. It may be configured to feed back.
  • the above-mentioned CSI can be calculated by the base station 100 instead of being calculated by the terminal 101 and fed back to the base station 100. It is.
  • FIG. 6 is a flowchart of an example of CSI calculation processing in the terminal according to the first embodiment. The process example which the CSI estimation part 321 of the terminal 101 demonstrated with the said system model performs is shown.
  • the CSI estimating unit 321 calculates SNR ⁇ k, s after demodulation when only the user data x B + 1 of the B + 1-th user is transmitted (step S601).
  • CSI estimation unit 321 calculates an interference alpha k, i from B-number of the user data x the user data x B + 1 of B + 1-th user (step S602).
  • step S603 the normalized signal power ⁇ k, b, s of the b-th beam when only x is transmitted , and the normalized interference power ⁇ k, b, i given to the b-th beam from a beam other than the b-th beam Is calculated.
  • CSI estimation section 321 feeds back the information calculated in steps S601 to S603 to base station 100 (step S604).
  • FIG. 7 is a flowchart of an example of scheduling in the base station according to the first embodiment.
  • the process example which the scheduler part 231 of the base station 100 performs is shown.
  • the scheduler unit 231 includes: A combination of users whose number of users is equal to or less than M for each beam and a user combination that maximizes the PF metric (for example, the ratio of instantaneous SINR to average SINR) and its power distribution are determined (step S701).
  • PF metric for example, the ratio of instantaneous SINR to average SINR
  • the scheduler unit 231 determines a user combination that maximizes the PF metric and its power distribution in a case where B users (user data) are multiplexed with beams and the B + 1-th user is non-orthogonal multiplexed (step S702). ).
  • the scheduler unit 231 The PF metric sum between beams in (Step S701) is 2. It is determined whether it is larger than the PF metric of (Step S702) (Step S703).
  • step S703 The PF metric sum between the two beams is 2. If the PF metric is larger than the PF metric (step S703: Yes), the scheduler unit 231 selects 1. Resources are allocated to the user combinations (step S704). On the other hand, The PF metric sum between the two beams is 2. 1. If it is not larger than the PF metric (step S703: No), Resources are allocated to the user combinations (step S705).
  • the scheduler unit 231 has, for each beam, a user combination in which the number of users in the combination is M or less and a power combination p ⁇ b, 1 , p ⁇ b, 2 ,. p ⁇ b,
  • fb is the PF metric in the b-th beam, It is expressed.
  • T k represents the average throughput of the kth user. Also, It is.
  • the power distributions p ⁇ and p ⁇ B + 1 for B + 1 and its user combination are determined (step S702 above).
  • g is a PF metric when B users are multiplexed with beams and the B + 1-th user is non-orthogonal multiplexed by non-orthogonal multiplexing, It is expressed.
  • k 1 , k 2 ,..., K B , k B + 1 are candidates, Those satisfying the conditions may be candidates.
  • the demodulated SNRk B and B + 1 are SNRk B Must be higher than +1 and B + 1 . That is, Must be met.
  • Step S703 in each beam, resources are allocated to the user combination S ⁇ b by power distribution p ⁇ b, 1 , p ⁇ b, 2 , ..., p ⁇ b,
  • Step S704 in each beam, resources are allocated to the user combination S ⁇ b by power distribution p ⁇ b, 1 , p ⁇ b, 2 , ..., p ⁇ b,
  • Step S704 on the other hand, (Step S703: No), k ⁇ 1 , k ⁇ 2 ,..., K ⁇ B users are beam-multiplexed, k ⁇ B + 1 users are non-orthogonal multiplexed, and power distribution p ⁇ , q ⁇ To allocate resources (step S705).
  • a is a parameter for phase adjustment for preventing transmission from only one antenna 219.
  • the signal is And transmitted from the two antennas 219 and 219 of the Downlink processing unit 201.
  • the base station performs non-orthogonal multiplexing of user data of a MIMO terminal and a transmission diversity terminal.
  • spatial multiplexing of user data of a plurality of terminals is performed, and user data of other terminals are further non-orthogonal multiplexed.
  • wireless communication by MU-MIMO is performed for a plurality of terminals close to the base station, and wireless communication by transmission diversity is performed for terminals remote from the base station, thereby improving the throughput of the terminals located at the cell edge. Plan.
  • communication with a transmission diversity terminal can be newly performed using a beam of communication with a MIMO terminal, the number of terminals communicating with the base station is increased without increasing the number of beams. And system capacity can be increased efficiently.
  • the presence / absence of non-orthogonal multiplexing based on MU-MIMO and transmission diversity is determined by comparing PF metrics before and after the combination of MU-MIMO and transmission diversity.
  • the term “before and after combination” refers to a time when only MU-MIMO is transmitted and a time when MU-MIMO and transmission diversity are combined.
  • the terminal measures the reception quality for each beam, the reception quality before and after the combination of MU-MIMO and transmission diversity, and the interference quality, and feeds back to the base station.
  • the base station can combine a plurality of terminals that improve the reception quality of each terminal with MU-MIMO and transmission diversity by scheduling according to the reception quality at the terminal, thereby preventing interference between terminals.
  • Embodiment 2 In Embodiment 1 described above, power is distributed between a user group that is beam-multiplexed and a user that is non-orthogonally multiplexed, so that the power between users that are beam-multiplexed is equal. In contrast, in the second embodiment, an example of power control between users that are beam-multiplexed will be described.
  • Embodiment 2 the configuration of base station 100 and terminal 101 (FIGS. 2 to 5) described in Embodiment 1 is used, and processing by scheduler section 231 of base station 100 and CSI estimating section 321 of terminal 101 is performed. The contents are different.
  • the channel matrix normalized by the deviation of the interference noise power in the CSI estimation unit 321 so that the SNR k, B + 1 when the base station 100 changes the transmission power can be calculated. And is fed back to the base station 100.
  • SNR k, b can also be calculated from the normalized channel matrix.
  • FIG. 8 is a flowchart of an example of CSI calculation processing in the terminal according to the second embodiment. The process example which the CSI estimation part 321 of the terminal 101 demonstrated with the said system model performs is shown.
  • the CSI estimating unit 321 calculates a channel matrix H k (norm) normalized by the deviation of interference noise power (step S801). Then, the CSI estimation unit 321 feeds back the information calculated in step S801 to the base station 100 (step S802).
  • the scheduler unit 231 of the base station 100 Similar to the first embodiment, the user combination S b having the maximum PF metric and the power distribution p ⁇ b, 1 , p ⁇ in the user combination in which the number of users in the combination is equal to or less than M for each beam. b, 2 ,..., p ⁇ b,
  • the user combinations k ⁇ 1 , k ⁇ 2 are determined.
  • the power distribution P ⁇ 1/2 , Q ⁇ 1/2 for B , k ⁇ B + 1 and its user combination is determined.
  • g is a PF metric when B users are multiplexed with beams and the B + 1-th user is non-orthogonal multiplexed by non-orthogonal multiplexing, It is expressed.
  • resources are allocated to the user combination Sb by power distribution p ⁇ b, 1 , p ⁇ b, 2 ,..., P ⁇ b,
  • k ⁇ 1 , k ⁇ 2 ,..., K ⁇ B users are beam-multiplexed
  • k ⁇ B + 1 users are non-orthogonal multiplexed
  • the same effects as those of the first embodiment are obtained.
  • the power distribution between the user group that is beam-multiplexed and the user that is non-orthogonally multiplexed is changed.
  • power distribution is performed to maximize the PF metric before and after the combination of MU-MIMO and transmission diversity.
  • MU-MIMO and transmission diversity are combined, for example, the reception quality of a terminal located at the cell edge can be made higher than a certain level, the throughput can be improved, and the PF Utility between users of the entire wireless system can be improved. become able to.
  • Embodiment 3 In Embodiment 1 described above, non-orthogonal multiplexing between a user group to be beam-multiplexed and a user to be non-orthogonally multiplexed is performed before precoding.
  • an example in which independent precoding is performed on a non-orthogonal multiplexed user (for example, terminal UE # 5) and non-orthogonal multiplexing is performed after precoding is given.
  • power distribution will be described using an example in which power control is performed collectively between a user group that performs beam multiplexing and a user that performs non-orthogonal multiplexing.
  • FIG. 9 is a diagram illustrating an internal configuration of the base station according to the third embodiment. 9, the same components as those in FIG. 2 (Embodiment 1) are denoted by the same reference numerals. As shown in FIG. 9, among the user data generation unit 211, the outputs of the B user data generation units 211a to be beam-multiplexed are precoded by the precoding unit 214a.
  • the output on the user data generation unit 211b side is precoded independently by the precoding unit 214b. Then, the non-orthogonal multiplexing unit 212 non-orthogonally multiplexes the output of the user data generation unit 211b to the output (user data) of the B user data generation units 211a to be beam-multiplexed.
  • the transmitted signal is It is expressed.
  • V is an N tx ⁇ B precoding matrix for beam-multiplexed users
  • u is an N tx ⁇ 1 precoding vector for non-orthogonal multiplexed users.
  • Total transmit power is However, It was.
  • the demodulated signal is Therefore, the demodulated SNR is It becomes.
  • the CSI estimation unit 321 includes the following information, the same normalized signal power ⁇ k, b, s as in the first embodiment, and the normalized interference power ⁇ k, b, i. Is fed back to the base station 100 as CSI.
  • the details (processing) of the scheduler unit 231 on the base station 100 side are the same as those in the first embodiment.
  • the same function and effect as in the first embodiment can be obtained.
  • independent precoding can be applied to a non-orthogonal multiplexed user (f, for example, terminal UE # 5).
  • non-orthogonal multiplexing is performed on the independent third beam by precoding.
  • the transmitted signal is It is expressed. However, It is. Using the above equation (3), the total transmission power is It becomes. However, It was. If the total transmission power is P, It becomes.
  • the received signal of the kth user is It can be expressed. Consider demodulating x B + 1 by maximum ratio combining.
  • the demodulated signal is Therefore, the demodulated SNR is It becomes.
  • a matrix representing the power distribution is included in the vector norm.
  • the CSI estimator 321 for the k-th user normalizes the deviation of the interference noise power so that the SNR k, B + 1 can be calculated when the base station 100 changes the transmission power. And is fed back to the base station 100. SNR k, b can also be calculated from the normalized channel matrix.
  • the scheduler unit 231 of the base station 100 will be described.
  • the user combinations k ⁇ 1 , k ⁇ 2 are determined.
  • the power distribution P ⁇ 1/2 , Q ⁇ 1/2 for B , k ⁇ B + 1 and its user combination is determined.
  • g is a PF metric when B users are multiplexed with beams and the B + 1-th user is non-orthogonal multiplexed by non-orthogonal multiplexing, It is expressed.
  • resources are allocated to the user combination S ⁇ b by power distribution p ⁇ b, 1 , p ⁇ b, 2 ,..., P ⁇ b,
  • k ⁇ 1 , k ⁇ 2 ,..., K ⁇ B users are beam-multiplexed
  • k ⁇ B + 1 users are non-orthogonal multiplexed
  • Embodiment 5 is an example in which non-orthogonal multiplexing in units of beams is performed to enable power control between beams.
  • a system model according to the fifth embodiment will be described.
  • the power of the b-th beam is q B.
  • the transmission signal vector of N tx ⁇ 1 is It can be expressed.
  • V is an N tx ⁇ N B precoding matrix, and V B represents the b-th column vector of V.
  • the received signal of the kth user is It can be expressed.
  • the demodulated signal of x b is It is expressed. Therefore, the SNR after demodulation is It becomes.
  • the CSI estimation unit 321 of the k-th user Is fed back to the base station 100.
  • ⁇ k, b is the normalized signal power when receiving the b-th beam
  • ⁇ k, b, b ′ is the normalized interference power from beams other than the b-th beam when receiving the b-th beam.
  • the normalized signal power and the standardized interference power may be fed back for all the beams, and in order to reduce the amount of information to be fed back, the standardized signal power and the standard only for the beam where ⁇ k, b is maximized.
  • the interference power may be fed back.
  • FIG. 10 is a flowchart of an example of CSI calculation processing in the terminal according to the fifth embodiment. The process example which the CSI estimation part 321 of the terminal 101 demonstrated with the said system model performs is shown.
  • the CSI estimating unit 321 calculates the normalized signal power ⁇ k, b of the b-th beam and the normalized interference power ⁇ k, b, b ′ given to the b-th beam from a beam other than the b-th beam (Ste S1001). Then, the CSI estimation unit 321 feeds back the information calculated in step S1001 to the base station 100 (step S1002).
  • FIG. 11 is a flowchart of an example of scheduling in the base station according to the fifth embodiment.
  • the process example which the scheduler part 231 of the base station 100 performs is shown.
  • the scheduler unit 231 of the base station 100 determines a user combination for each beam that maximizes the sum of PF metrics between beams, a power distribution between users for each beam, and a power distribution between beams (step S1101). Thereafter, resources are allocated to the user combination determined in step S1101 (step S1102).
  • the scheduler unit 231 determines a user combination for each beam that maximizes the sum of PF metrics between beams, a power distribution between users for each beam, and a power distribution between beams.
  • a user combination loop and a PF metric sum maximization step for the user combination are divided.
  • the PF metric sum maximization step is divided into an inter-user power allocation step and an inter-beam power allocation step for each beam.
  • the power distribution step between users for every t-th beam is as follows: It becomes.
  • the vertex having the maximum inner product with the gradient vector is set as the update direction (determination of the update direction).
  • ⁇ and ⁇ are predetermined set values.
  • Embodiment 5 non-orthogonal multiplexing in units of beams can be performed and power control between the beams can be performed, so that each beam can be set to an appropriate power corresponding to the position of the user (terminal), and the reception quality at the terminal. Can be improved.
  • the base station performs non-orthogonal multiplexing of user data to be transmitted to a MIMO terminal and a transmission diversity terminal.
  • spatial multiplexing of a plurality of terminals is performed, and further other users are non-orthogonal multiplexed.
  • wireless communication by MU-MIMO is performed for a plurality of terminals close to the base station, and wireless communication by transmission diversity is performed for a terminal located at a cell edge away from the base station.
  • the number of terminals communicating with the base station is increased without increasing the number of beams. Can increase system capacity efficiently.
  • the presence / absence of non-orthogonal multiplexing based on MU-MIMO and transmission diversity is determined by comparing PF metrics before and after the combination of MU-MIMO and transmission diversity.
  • the terminal measures the reception quality for each beam, the reception quality before and after the combination of MU-MIMO and transmission diversity, and the interference quality, and feeds back to the base station.
  • the base station can perform scheduling based on the reception quality measured by the terminals, prevent interference between the terminals, and obtain an optimal combination of multiple terminals that improves the reception quality of each terminal. Become.
  • the throughput of the terminal located at the cell edge can be improved.
  • the base station can efficiently allocate resources to a plurality of user data.
  • Base station 101 terminal (UE) 101 Downlink processing unit 202 Uplink processing unit 211 User data generation unit 212 Non-orthogonal multiplexing unit 213 Beam power adjustment unit 214 Precoding unit 215 Channel multiplexing unit 216 IFFT unit 217 CP addition unit 218 Downlink wireless processing unit 219, 241, 311 , 333 Antenna 221 Error correction encoding unit 222 Modulation unit 223 Power adjustment unit 231 Scheduler unit 232 Downlink control signal generation unit 242 Uplink radio processing unit 243 Uplink control information extraction unit 301 Downlink processing unit 302 Uplink processing unit 3k3 processing unit 312 Downlink processing unit 312 CP removing unit 314 FFT unit 315 Channel demapping unit 316 Spatial filter unit 317 Canceling unit 318 Demodulating unit 319 Error correction decoding Unit 320 Ack / Nack generation unit 321 CSI estimation unit 322 Downlink control signal demodulation / decoding unit 331 Uplink transmission unit 332 Uplink wireless processing unit

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Transmission System (AREA)

Abstract

Selon l'invention, la station de base (100) comporte une unité de commande qui multiplexe spatialement une pluralité d'éléments de données d'utilisateur devant être transmises à une pluralité de terminaux n ° 1 à n ° 4 (101), et multiplexe de manière non orthogonale, avec les données d'utilisateur multiplexées spatialement, des données d'utilisateur devant être transmises à un autre terminal n ° 5 (101). La station de base (100) est pourvue d'unités de traitement radioélectriques comprenant une pluralité d'antennes, transmet la pluralité d'éléments de données d'utilisateur à la pluralité de terminaux n ° 1 à n ° 4 (101) au moyen de faisceaux multiples en utilisant MU-MIMO à travers une pluralité d'unités de traitement radio, et transmet les données d'utilisateur à l'autre terminal n ° 5 (101) à travers une diversité de transmission multi-faisceau.
PCT/JP2015/074815 2015-08-31 2015-08-31 Station de base, terminal, système de communication sans fil, et procédé de communication sans fil WO2017037861A1 (fr)

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EP3621214A1 (fr) * 2018-09-10 2020-03-11 Beammwave AB Élément d'émetteur/récepteur de formation de faisceaux
US10897299B2 (en) 2017-11-09 2021-01-19 Nec Corporation Wireless apparatus, wireless communication method, and program

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JP2014154962A (ja) * 2013-02-06 2014-08-25 Ntt Docomo Inc 無線基地局、ユーザ端末及び無線通信方法

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JP2012100098A (ja) * 2010-11-02 2012-05-24 Sharp Corp 基地局装置、移動局装置及びそれらを用いた無線通信システム
JP2014154962A (ja) * 2013-02-06 2014-08-25 Ntt Docomo Inc 無線基地局、ユーザ端末及び無線通信方法

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US10897299B2 (en) 2017-11-09 2021-01-19 Nec Corporation Wireless apparatus, wireless communication method, and program
EP3621214A1 (fr) * 2018-09-10 2020-03-11 Beammwave AB Élément d'émetteur/récepteur de formation de faisceaux
WO2020052880A1 (fr) * 2018-09-10 2020-03-19 Beammwave Ab Élément émetteur-récepteur pour formation de faisceau
CN112640315A (zh) * 2018-09-10 2021-04-09 波束公司 用于波束成形的收发器元件
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