WO2020194428A1 - Station de base radio de niveau inférieur et procédé de commande de nombre de flux de multiplexage spatial - Google Patents

Station de base radio de niveau inférieur et procédé de commande de nombre de flux de multiplexage spatial Download PDF

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Publication number
WO2020194428A1
WO2020194428A1 PCT/JP2019/012390 JP2019012390W WO2020194428A1 WO 2020194428 A1 WO2020194428 A1 WO 2020194428A1 JP 2019012390 W JP2019012390 W JP 2019012390W WO 2020194428 A1 WO2020194428 A1 WO 2020194428A1
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Prior art keywords
base station
matrix
radio base
terminal
destination
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PCT/JP2019/012390
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English (en)
Japanese (ja)
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西本　浩
明▲徳▼ 平
彰浩 岡崎
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三菱電機株式会社
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Priority to PCT/JP2019/012390 priority Critical patent/WO2020194428A1/fr
Priority to JP2021508405A priority patent/JP7003324B2/ja
Publication of WO2020194428A1 publication Critical patent/WO2020194428A1/fr

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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
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • 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
    • H04B7/0452—Multi-user MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering

Definitions

  • the present invention relates to a method for controlling a lower radio base station and the number of spatial multiplex streams in a wireless communication system to which the MIMO (Multiple-Input Multiple-Output) method is applied.
  • MIMO Multiple-Input Multiple-Output
  • a MIMO system in which multiple antennas are installed on both transmitters and receivers is connected to a space division multiple access (SDMA: Space Division Multiple Access).
  • SDMA Space Division Multiple Access
  • MU Multi-User
  • the MU-MIMO system is a system in which a base station having a plurality of antennas and a plurality of terminals having a plurality of antennas are provided, and the base station simultaneously transmits to a plurality of terminals in the same radio frequency band.
  • the 5th generation mobile communication in addition to the conventional mobile communication, that is, the same frequency band as before the 4th generation mobile communication, it is expected to utilize radio waves in a higher frequency band than before.
  • the higher the frequency the stronger the straightness of the radio wave, and the greater the attenuation with respect to the propagation distance.
  • High frequency radio waves are blocked when they hit a building such as a building, and the propagation distance of the base station is shortened. Therefore, when using a high frequency band, the communication area covered by one base station, that is, The cells will be smaller than before, and the number of base stations is expected to increase compared to before the 4th generation mobile communication.
  • Patent Document 1 discloses a radio base station system that is divided into a higher radio base station and a lower radio base station.
  • the upper radio base station selects terminals for data transmission in the upper scheduler unit, determines the data transmission speed or data transmission amount of each terminal, and notifies the lower radio base station of these.
  • the lower radio base station determines the number of signal streams of each terminal based on the data transmission speed of the terminal and the terminal determined by the upper scheduler, and performs MU-MIMO precoding for each terminal to perform MU-MIMO precoding to the destination terminal.
  • MU-MIMO transmission is performed. Since the wireless base station system described in Patent Document 1 is composed of an upper wireless base station and a lower wireless base station which is a base station capable of wirelessly connecting to a mobile terminal, the lower wireless base station can be realized with a simple configuration. Will be done.
  • the lower radio base station described in Patent Document 1 transmits a signal stream to a terminal determined by a higher scheduler, and this signal stream has a high spatial correlation between a plurality of antennas included in the terminal or between terminals. It may be a signal stream.
  • the throughput of the lower radio base station and the signal power to interference noise power ratio (SINR: Signal-to-Interference plus Noise power Ratio) can be obtained. There was a problem that the communication quality deteriorated.
  • the present invention has been made in view of the above, and an object of the present invention is to obtain a lower radio base station capable of suppressing deterioration of throughput and communication quality.
  • the lower radio base station sets a plurality of destination terminals to which signal streams are assigned and data transmission speeds of the plurality of destination terminals as higher radio base stations. Is notified from, and based on multiple destination terminals and data transmission speed, a matrix based on the state of the transmission line corresponding to multiple destination terminals is calculated, and the absolute value of the elements of the stream is a predetermined threshold value.
  • a rank control unit that determines the number of signal streams of the destination terminal so as not to use a transmission line that does not satisfy the above, and a signal processing unit that performs Multi User-Multiple Input Multiple Output precoding on the signal stream corresponding to the destination terminal. It is characterized by having.
  • the lower radio base station according to the present invention has the effect of suppressing deterioration of throughput and communication quality.
  • FIG. 1 is a diagram showing a configuration example of a radio base station system according to an embodiment.
  • the radio base station system 100 includes an upper base station 10 and lower base stations 20-1 to 20-M (M is an integer of 1 or more).
  • the higher-level base station 10 is a radio base station that performs higher-level scheduling described later.
  • the lower base stations 20-1 to 20-M are shown without distinction, they are appropriately referred to as lower base stations 20.
  • the lower base station 20 is a radio base station that performs lower scheduling, which will be described later.
  • the wireless base station system 100 connects to MBH (Mobile Back Haul) and transmits / receives data to / from MBH.
  • MBH is a network defined by 3GPP (Third Generation Partnership Project) or ITU-R (International Telecommunication Union Radiocommunication Sector), and higher-level network devices such as SGSN (Serving General-packet-radio-service Support Node) are installed. It is a network that connects between the sites and the base station.
  • SGSN is one of the nodes that make up the core network of mobile terminals defined by 3GPP, and controls information such as user authentication and IP (Internet Protocol) address during packet communication.
  • the cells each subordinate base station 20 forms a radio base station system 100 includes the mobile terminal 90-1-1 ⁇ 90-M-K M is present.
  • the cell formed by the lower base station 20-m (m is an integer of 1 ⁇ m ⁇ M)
  • j (j is an integer of 1 or more) of mobile terminals 90-m-1 to 90-m-j. are doing.
  • the downlink data of each terminal that is, the communication data in the direction from the base station to the terminal is input from the MBH to the radio base station system 100 and transmitted from the radio base station system 100 to each terminal.
  • the MU-MIMO system is applied to the radio base station system 100 of the present embodiment.
  • MU-MIMO downlink In the downlink in the MU-MIMO system (hereinafter referred to as MU-MIMO downlink), a signal is sent from the base station to each terminal at the same time.
  • the uplink is excluded from the scope of the MU-MIMO method in the present invention.
  • the communication performance of the MU-MIMO downlink largely depends on the state of the transmission line between the base station and the terminal. Therefore, the base station has a combination of terminals that transmit MU-MIMO downlink, the number of signal streams that transmit the downlink to each terminal, that is, the number of ranks (RI: Rank Indicator), and the stream of each signal. It is necessary to determine the modulation method and the MCS (Modulation and Coding Scheme), which is an error correction coding method. This is because RI and MCS need to be determined according to the transmission line condition.
  • a signal stream is a spatial multiplex signal sequence transmitted by a base station to each terminal.
  • RI indicates the number of signal streams used in standards such as IEEE802.11n and LTE (Long Term Evolution) -Advanced
  • MCS is an index indicating a combination of a primary modulation method and an error correction coding method.
  • the base station determines the data transmission rate by using the determined MCS modulation method and error correction coding method.
  • the process of determining the combination of terminals that transmit MU-MIMO downlink, the number of signal streams RI that transmit the downlink to each terminal, and the MCS of each signal stream is generally called scheduling, and is a process of performing scheduling.
  • the part is commonly called a scheduler.
  • the base station can acquire the CSI of each terminal by estimating the CSI using the uplink signal transmitted from the terminal to the base station.
  • the method in which the base station acquires the CSI of each terminal is not limited to this, and may be, for example, a method in which the CSI estimated value estimated on the terminal side is fed back from the terminal side to the base station.
  • the base station performs radio signal processing for MU-MIMO downlink, that is, MU-MIMO signal processing based on the information determined by the scheduler, and outputs MU-MIMO downlink signals from a plurality of antennas provided in the base station.
  • MU-MIMO signal processing include error-correction coding for data signals for each terminal and precoding for spatial multiplexing of all terminals for a plurality of signal streams generated by primary modulation.
  • the MU-MIMO signal processing is not limited to precoding, and may be any processing as long as it is a radio signal processing that realizes the MU-MIMO downlink.
  • FIG. 2 is a diagram showing a configuration example of the upper base station 10 according to the present embodiment.
  • the upper base station 10 has a resource control unit 11.
  • the resource control unit 11 has M upper scheduler units 12-1 to 12-M corresponding to each of the M lower base stations 20.
  • the upper scheduler units 12-1 to 12-M are shown without distinction, they are appropriately referred to as the upper scheduler unit 12.
  • the upper scheduler unit 12-m selects L m (L m is an integer of 1 or more and j or less) of mobile terminals that actually transmit data from j mobile terminals.
  • the selection method is the terminal capacity index or CSI for j units notified from the lower base station 20-m and the required value (or data transmission amount) of the data transmission speed or data transmission amount for j mobile terminals input from MBH. This method is selected in consideration of the amount of standby buffer for data transmission).
  • the upper scheduler unit 12-m determines the data transmission speed or the data transmission amount of each mobile terminal. This process is called upper scheduling.
  • the terminal capacity index of each mobile terminal is a real number scalar amount, and the details are described in Patent Document 1.
  • the upper scheduler unit 12-m notifies the lower base station 20-m of the selected destination terminal and the requested data transmission speed of each destination terminal.
  • the destination terminal is a mobile terminal in the Lm range selected by the upper scheduler unit 12-m.
  • the upper-level scheduler unit 12-m is L m in order from the mobile terminals having the required terminal capacity index or more among the j mobile terminals, in descending order of the data transmission request value.
  • the required data transmission speed of the selected destination terminal the maximum data transmission speed can be used among those that do not exceed the terminal capacity index of the destination terminal, but this is not the case.
  • FIG. 3 is a diagram showing a configuration example of the lower base station 20 according to the present embodiment.
  • the lower base station 20-m will be described as an example.
  • the lower base stations 20-1 to 20-M all have the same configuration.
  • the number of antennas provided in the lower base station 20-m is T m (T m is an integer of 1 or more), and the number of mobile terminals existing in the cell formed by the lower base station 20-m is j.
  • the lower base station 20-m includes a lower scheduler unit 21, a radio baseband signal processing unit 22, a radio RF (Radio Frequency) signal processing unit 23, and T m antennas 24-1 to 24-T m . Be prepared.
  • the lower scheduler unit 21 includes a rank control unit 211.
  • the wireless baseband signal processing unit 22 includes a CSI acquisition unit 221 and a MU-MIMO signal processing unit 222. Further, the CSI acquisition unit 221 is also simply referred to as an acquisition unit.
  • the MU-MIMO signal processing unit 222 is also simply referred to as a signal processing unit.
  • the radio RF signal processing unit 23 is also simply referred to as a radio signal processing unit.
  • the subordinate scheduler is also simply called the scheduler.
  • the CSI acquisition unit 221 acquires the CSI by estimating from the uplink signal from the mobile terminals 90-m-1 to 90-m-j to the lower base station 20-m, and transfers this CSI to the lower scheduler unit 21. input.
  • the estimation method is not particularly limited, and a general method may be used.
  • MU-MIMO signal processing unit 222 to generate a baseband signal for MU-MIMO downlink L m stand destination terminal that is selected by the upper scheduler section 12.
  • the radio RF signal processing unit 23 converts the MU-MIMO downlink baseband signal into a radio signal having a radio RF frequency.
  • Antennas 24-1 ⁇ 24-T m sends a wireless RF signal to each destination terminal.
  • the lower scheduler unit 21 abstracts the CSI of j terminals input from the CSI acquisition unit 221 as the transmission path capacity of the terminals so that the upper scheduler unit 12-m can easily handle it, that is, a single real number scalar. Convert to quantity.
  • the transmission line capacity indicates the amount of data that can be downlinked to the terminal.
  • the transmission line capacity can generally be calculated from the transmission line information. It is expected that the number of terminals and the number of antennas will increase in the future, which will increase the amount of information of the transmission line information itself, and there is a possibility that the line will be tight when the transmission line information itself is transmitted.
  • the lower scheduler unit 21 transmits a terminal capacity index, which is a CSI converted into a single real number scalar amount, to the upper scheduler unit 12.
  • MIMO transmission capacity is an example of a scalar quantity that can express the characteristics of CSI, that is, can be abstracted. MIMO transmission capacity is also referred to as channel capacity, channel capacity, or Shannon capacity.
  • the terminal capacity index C m, j (f) disclosed in Patent Document 1 is used. f is a radio RF frequency between the lower base station 20-m and the mobile terminal 90-m-j.
  • the resource control unit 11, the upper scheduler unit 12, the lower scheduler unit 21, the wireless baseband signal processing unit 22, the rank control unit 211, the CSI acquisition unit 221 and the MU-MIMO signal processing unit 222 are electronic circuits that perform each processing. It is realized by a certain processing circuit.
  • the radio RF signal processing unit 23 is a transmitter and a receiver.
  • This processing circuit may be dedicated hardware or a control circuit including a memory and a CPU (Central Processing Unit, central processing unit) that executes a program stored in the memory.
  • the memory corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), or a flash memory, a magnetic disk, an optical disk, or the like.
  • FIG. 4 is a diagram showing a configuration example of the control circuit of the embodiment.
  • This control circuit is, for example, the control circuit 400 having the configuration shown in FIG.
  • the processing circuit is, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.
  • the control circuit 400 includes a processor 400a which is a CPU and a memory 400b.
  • a processor 400a which is a CPU and a memory 400b.
  • the processor 400a reading and executing the program corresponding to each process stored in the memory 400b.
  • the memory 400b is also used as a temporary memory in each process performed by the processor 400a.
  • a plurality of destination terminals that perform MU-MIMO transmission and data transmission speeds of each destination terminal are instructed from the upper base station 10 to the lower base station 20.
  • the lower base station 20 performs lower scheduling based on the instruction from the upper base station 10.
  • MU-MIMO transmission the configuration of the entire MIMO transmission line matrix changes depending on the combination of destination terminals and the number of signal streams to each destination terminal, and the determination of these parameters affects the transmission characteristics. Therefore, it is considered better to have a standard for tentatively determining the number of streams transmitted by the lower base station 20.
  • the lower base station 20 may indicate at least one to all the destination terminals in the lower scheduling, in addition to instructing the data transmission speeds of the plurality of destination terminals and each destination terminal that perform MU-MIMO transmission from the upper base station 10.
  • One is to allocate a signal stream.
  • the lower base station 20 may preferentially allocate a signal stream to a destination terminal having a high data transmission speed required for the destination terminal.
  • the time that one stream is transmitted is determined in units of subframes or slots specified by 3GPP. In the case of LTE, the stream is transmitted every 1 ms. In the case of 5G (5th Generation), the stream is transmitted every 0.5 ms or 0.25 ms.
  • the rank control unit 211 determines the number of signal streams to be transmitted to each destination terminal based on the provisional precoding matrix operation so as to satisfy the above-mentioned lower scheduling criteria.
  • the provisional precoding matrix operation will be explained.
  • the provisional precoding matrix operation is an operation based on the inverse matrix for determining the number of signal streams. Further, the provisional precoding matrix operation is different from the precoding matrix operation for MU-MIMO precoding used by the MU-MIMO signal processing unit 222 described later for downlink transmission.
  • the four destination terminals be terminal a, terminal b, terminal c, and terminal d, respectively.
  • the transmission line matrices Aa, Ab, Ac, and Ad of 2 rows and 8 columns (number of rows: number of receiving antenna ports, number of columns: number of base station transmitting antenna ports Tm ) corresponding to each terminal are expressed by equations (1) and (1) and (A), respectively. It is defined as (2), equation (3), and equation (4).
  • the characters indicating the matrix are shown in bold in the mathematical formula, but are shown in normal characters in the text.
  • the entire transmission line matrix A of 8 rows and 8 columns, which is composed of the transmission line matrix of each terminal as a submatrix, is defined as in equation (5). It can be said that the entire transmission line matrix A is a matrix indicating the state of the transmission lines corresponding to a plurality of destination terminals.
  • the rank control unit 211 reflects the priority order so as to give priority to the destination terminal having the faster data transmission speed of the lower scheduling described above, and sets the submatrix of the entire transmission line matrix A as in the equation (6).
  • the matrix in which the submatrix of the entire transmission line matrix A is replaced as in Eq. (6) is defined as the total transmission line matrix A ⁇ .
  • the rank control unit 211 picks up one antenna corresponding to the receiving port from each terminal for four lines. Are arranged from the top in the order of priority of terminal d, terminal b, terminal a, and terminal c, and the remaining four lines are arranged in the same order of priority. This is referred to as the entire transmission line matrix A ⁇ ⁇ .
  • the entire transmission line matrix A ⁇ ⁇ is represented by the equation (7).
  • a T indicates the transpose of the vector and the matrix. Swapping rows in the above matrix is an operation that improves the convenience of calculation without changing the characteristics of the transmission line matrix.
  • the rank control unit 211 aims to orthogonalize the transmission line space by using the MP (Moore-Penrose) general inverse matrix of the entire transmission line matrix.
  • the provisional precoding matrix W is obtained by the MP general inverse matrix of the total transmission line matrix A ⁇ ⁇ shown in the equation (8).
  • the MP general inverse matrix is also called a matrix calculated based on the state of the transmission line corresponding to a plurality of destination terminals.
  • a + 1 is the MP general inverse matrix operator
  • a H is the Hermitian transpose of vectors and matrices.
  • the third elementary transformation is a transformation that adds a constant multiple of one row to another.
  • the Gauss-Jordan method is a classical inverse matrix solution method (simultaneous linear equation solution method) in linear algebra, and detailed explanation of the principle is omitted here.
  • An augmented matrix D of 8 rows and 16 columns, each of which is a submatrix of an eighth-order Hermitian matrix B to be calculated and an eighth-order square matrix C in which an identity matrix is set as an initial value, is defined as in equation (10).
  • the range of the submatrix B is finally calculated as the identity matrix, and the range of the submatrix C is calculated as the inverse matrix. ..
  • the reciprocal of the value of the n-row n-column element may be multiplied by the nth row.
  • the reciprocal becomes close to dividing by 0 and tends to diverge, and such a case must be avoided.
  • Each line corresponds to a receiving antenna port, and this event occurs when the spatial correlation between terminal antennas and between terminals is high due to the receiving antenna port. Therefore, if the receiving antenna port is included in MU-MIMO and precoding is applied, the transmission performance may deteriorate.
  • the threshold value ⁇ is introduced, and the rank control unit 211 checks the size of the diagonal element in the nth stage. If the threshold value ⁇ is a real scalar value greater than 0 and the absolute value of the diagonal element is smaller than the threshold value ⁇ , the nth row and nth column of the submatrix B and C are deleted, and the submatrix is deleted. The calculation proceeds by reducing the order of B and C by one. That is, the number of rows of the augmented matrix D is reduced by one, and the number of columns is reduced by two. The number of rows of the augmented matrix D remaining after all the calculation stages are completed is the calculated number of ranks of MU-MIMO.
  • Inverse matrix operations by the Gauss-Jordan method generally start from the top row. Therefore, at least the first row is not omitted and the inverse matrix operation is performed, and the inverse matrix operation is performed with the highest priority.
  • the second line of the equation (9) is orthogonalized to the first line
  • the third line is orthogonalized to the first and second lines. In this way, since the number of rows that are orthogonalized increases in the lower rows, the diagonal elements due to orthogonalization tend to be less than the threshold value in the lower rows, and the probability of being excluded increases in the lower rows.
  • the rank control unit 211 first compares the size
  • ⁇ ⁇ it is assumed that
  • the second stage calculation is performed according to the usual Gauss-Jordan method.
  • the augmented matrix D has the form of equation (12).
  • the augmented matrix D becomes the form of the equation (13) after the completion of the fifth stage. ..
  • the rank control unit 211 compares the sizes of the 6-row, 6-column elements in the range of the submatrix B
  • the augmented matrix D has the form of equation (14).
  • the operation of the rank control unit 211 calculates a matrix calculated based on the state of the transmission line corresponding to the plurality of destination terminals based on the plurality of destination terminals and the data transmission speed, and the absolute elements of the matrix are calculated. It can be said that this is an operation of determining the number of signal streams of the destination terminal so as not to use a transmission line whose value does not satisfy a predetermined threshold value.
  • the rank control unit 211 compares the size
  • the operation of the sixth stage is performed according to the usual Gauss-Jordan method.
  • the augmented matrix D has the form of equation (15).
  • the rank control unit 211 performs the operations of the 7th stage according to the normal Gaussian-Jordan method, and as a result of a series of operations, the augmented matrix D is finally obtained. Is in the form of equation (16).
  • the matrix A' ⁇ ⁇ is a matrix of 7 rows and 8 columns excluding the 6th row from the matrix A ⁇ ⁇ as represented by the equation (17).
  • Submatrix of the left half of the matrix of Equation (16) is calculated as the inverse matrix of A' ⁇ ⁇ A' ⁇ ⁇ H.
  • the provisional precoding matrix is calculated by the rank control unit 211 as in equation (18).
  • the terminal b was calculated as having one signal stream, and the other terminals a, c, and terminal d were calculated as having two signal streams. Therefore, the total number of MU-MIMO signal streams is 7.
  • An example is a specific method for determining MCS in the lower scheduler unit 21.
  • MCS since the number of signal streams of each destination terminal, that is, RI is determined, MCS according to RI so as to satisfy the requested data transmission speed in order from the terminal having the highest notified requested data transmission speed. To determine.
  • the MCS is determined using the determined RI and the SNR estimate using the vector of the provisional precoding matrix described above. In this way, the MCS is determined in order for each destination terminal.
  • two MCS determination methods have been illustrated, but the present invention is not limited to this, and other methods may be used.
  • the MU-MIMO signal processing unit 222 performs MU-MIMO precoding on the signal stream corresponding to the destination terminal, but there is no limitation on the precoding method, and even if linear precoding represented by block diagonalization is performed. Alternatively, non-linear precoding represented by THP (Tomlinson Harashima Precoding) may be performed.
  • the lower scheduler unit 21 also determines the order of L m stand destination terminal. As a criterion for determining, for example, the size of the terminal capacity index, the order of the SNR estimated value using the vector of the provisional precoding matrix described above, the order of the angle of the terminal as seen from the lower base station 20, between the terminals. The positional relationship of the terminals is geographically close or far, and the movement speed of the terminal is in order, but these are not limited to these.
  • the number of signal streams that can be transmitted is obtained by orthogonalizing the transmission path space. Therefore, the lower base station 20 suppresses deterioration of throughput and communication quality by not allocating a signal stream having a high spatial correlation between terminal antennas and terminals except for rows and columns in which matrix elements below the threshold value appear. can do.
  • the configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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Abstract

L'invention concerne une station de base de niveau inférieur (20) étant caractérisée en ce qu'elle comprend : une unité de commande de rang (211), qui est notifiée d'une pluralité de terminaux de destination auxquels des flux de signaux doivent être attribués et un débit de transmission de données de la pluralité de terminaux de destination à partir d'une station de base radio de niveau supérieur, calculant une matrice sur la base des états de canaux correspondant à la pluralité de terminaux de destination sur la base de la pluralité de terminaux de destination et du débit de transmission de données, et déterminant le nombre de flux de signaux des terminaux de destination respectifs de telle sorte qu'un canal dans lequel les valeurs absolues des éléments de la matrice ne satisfont pas une valeur seuil prédéterminée n'est pas utilisé ; et une unité de traitement de signal MU-MIMO (222) qui effectue un précodage à entrées multiples et sorties multiples multiutilisateur sur les flux de signaux correspondant aux terminaux de destination respectifs.
PCT/JP2019/012390 2019-03-25 2019-03-25 Station de base radio de niveau inférieur et procédé de commande de nombre de flux de multiplexage spatial WO2020194428A1 (fr)

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JP2021508405A JP7003324B2 (ja) 2019-03-25 2019-03-25 下位無線基地局、空間多重ストリーム数の制御方法、制御回路およびプログラム

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WO2023135708A1 (fr) * 2022-01-13 2023-07-20 日本電気株式会社 Dispositif de commande, procédé de commande, et support d'enregistrement

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