WO2015084051A1 - Procédé de rétroaction de csi, et appareil d'un système d'antennes multiples - Google Patents

Procédé de rétroaction de csi, et appareil d'un système d'antennes multiples Download PDF

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Publication number
WO2015084051A1
WO2015084051A1 PCT/KR2014/011771 KR2014011771W WO2015084051A1 WO 2015084051 A1 WO2015084051 A1 WO 2015084051A1 KR 2014011771 W KR2014011771 W KR 2014011771W WO 2015084051 A1 WO2015084051 A1 WO 2015084051A1
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codebook
layers
precoding matrix
csi
domain
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PCT/KR2014/011771
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English (en)
Korean (ko)
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리지안준
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주식회사 아이티엘
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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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0478—Special codebook structures directed to feedback optimisation
    • 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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • 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
    • 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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/046—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account
    • H04B7/0469—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account taking special antenna structures, e.g. cross polarized antennas into account

Definitions

  • the present invention relates to wireless communications, and more particularly, to a method and apparatus for channel state information (CSI) feedback in a multi-antenna system.
  • CSI channel state information
  • the mobile communication system can support eight transmit antennas for beamforming operation.
  • the same physical resource block (PRB) may be scheduled or allocated to up to four user equipments (UEs). have.
  • UEs user equipments
  • a closely-spaced X-polarized antenna is considered, for example, from 0.5 ⁇ to 0.7 ⁇ .
  • the current mobile communication system only considers the antenna arrangement in the horizontal direction for beamforming operation. Meanwhile, in order to further improve MIMO performance, it is necessary to introduce a full dimension (MID) MIMO supporting both a horizontal direction and a vertical direction.
  • MID full dimension
  • next generation mobile communication system aims to support up to 64 transmit antennas in a two-dimensional antenna configuration with respect to a closed loop (CL) MIMO operation.
  • CL closed loop
  • 8 APs FD MIMO scheme supporting 8 antenna ports (AP) based on a 2D array should be supported.
  • CSI feedback for stably supporting FD MIMO including up to eight transmit antennas is an important issue, and a new precoding codebook design for eight APs is required.
  • One example of the present invention is to provide a CSI feedback method and apparatus in a multiple antenna system.
  • Another example of the present invention is to provide an apparatus and method for designing a codebook for supporting FD MIMO.
  • Another example of the present invention is to provide an apparatus and method for designing a codebook in consideration of two-dimensional beamforming or layer mapping.
  • a method of supporting a full dimension (FD) multiple-input multiple-output (MIMO) by a terminal in a multi-antenna system includes Channel State Information (CSI) including Precoding Matrix Index (PMI) 1 corresponding to the horizontal domain, PMI 2 corresponding to the vertical domain, and Rank Indication (RI) indicating the number of layers for downlink transmission. Transmitting the precoded data from the base station based on the detected precoding matrix based on the PMI1, the PMI2, and the RI, wherein the precoding matrix is the RI. It is included in the codebook defined according to the number of layers indicated by the codebook, characterized in that based on the Discrete Fourier Transform (DFT) beam vector.
  • DFT Discrete Fourier Transform
  • a method for supporting FD MIMO in a multi-antenna system may further include receiving, from the terminal, a CSI including a PMI1 corresponding to the horizontal domain, a PMI2 corresponding to the vertical domain, and an RI indicating a number of layers related to downlink transmission, based on the RI. Determining a codebook according to the number of times, detecting a precoding matrix in the codebook based on the PMI1 and the PMI2, and generating precoded data based on the detected precoding matrix; And transmitting the precoded data to the terminal, wherein the codebook is based on a DFT beam vector.
  • a terminal supporting FD MIMO in a multi-antenna system receives a CSI-RS (Channel State Information Reference Signal) through the four antenna ports for the horizontal domain and the four antenna ports for the vertical domain from the base station, based on the CSI-RS
  • the processor detects a codebook based on a DFT beam vector and a precoding matrix included in the codebook based on the PMI1, the PMI2, and the RI, and the receiver based on the detected precoding matrix Receiving precoded data from the base station.
  • a codebook optimized for 2D beamforming or FD MIMO in consideration of codeword layer mapping is provided. To provide an advantage. Thus, system throughput performance can be improved.
  • FIG. 1 shows a wireless communication system to which the present invention is applied.
  • FIGS. 2 and 3 illustrate a CSI-RS pattern according to an example of the present invention.
  • FIG. 4 illustrates a multiple antenna system according to an example of the present invention.
  • 5 shows an example of codeword layer mapping for 5 layer transmission.
  • 6 shows an example of codeword layer mapping for 6 layer transmission.
  • FIG. 9 is an example of an explanatory diagram showing a precoding method in an FD MIMO system according to an embodiment of the present invention.
  • FIG. 10 is an example of a block diagram illustrating a terminal and a base station according to an embodiment of the present invention.
  • the present specification describes a wireless communication network
  • the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.
  • 'transmitting a channel' may be interpreted as meaning transmitting information through a specific channel.
  • the channel is a concept including both a control channel and a data channel
  • the control channel may be, for example, a physical downlink control channel (PDCCH) or a physical uplink control channel (PUCCH).
  • the data channel may be, for example, a Physical Downlink Shared CHannel (PDSCH) or a Physical Uplink Shared CHannel (PUSCH).
  • FIG. 1 shows a wireless communication system to which the present invention is applied.
  • the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data.
  • the wireless communication system 10 includes at least one base station 11 (evolved-NodeB, eNB).
  • Each base station 11 provides a communication service for specific cells 15a, 15b, and 15c.
  • One base station may be responsible for multiple cells.
  • the base station 11 refers to a transceiver for performing information and control information sharing with the terminal for cellular communication, and includes a base station (BS), a base transceiver system (BTS), an access point (Access Point), Other terms, such as a femto base station, a home node B, a relay, and the like, may be called.
  • a cell is meant to encompass all of the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell, and the like.
  • the UE 12 may be fixed or mobile and may have a mobile station (MS), a mobile terminal (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms.
  • MS mobile station
  • MS mobile terminal
  • MT mobile terminal
  • UT user terminal
  • SS subscriber station
  • PDA personal digital assistant
  • wireless modem wireless modem
  • handheld device handheld device
  • downlink refers to a transmission link from the base station 11 to the terminal 12
  • uplink refers to a transmission link from the terminal 12 to the base station 11. it means.
  • the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12.
  • the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11.
  • CDMA Code Division Multiple Access
  • TDMA Time Division Multiple Access
  • FDMA Frequency Division Multiple Access
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single Carrier-FDMA
  • OFDM-FDMA OFDM-FDMA
  • OFDM-TDMA OFDM-FDMA
  • OFDM-TDMA OFDM-FDMA
  • various multiple access schemes such as OFDM-CDMA may be used.
  • the uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.
  • TDD time division duplex
  • Layers of a radio interface protocol between the terminal 12 and the base station 11 are based on the lower three layers of the Open System Interconnection (OSI) model, which is well known in communication systems.
  • the layer L1 may be divided into a second layer L2 and a third layer L3.
  • the physical layer belonging to the first layer provides an information transfer service using a physical channel.
  • a physical downlink control channel is a hybrid automatic repeat request (HARQ) related to resource allocation and DL-SCH of a paging channel (PCH) and a downlink shared channel (DL-SCH) to the terminal 12.
  • the PDCCH may carry an uplink grant that informs the terminal 12 of resource allocation of uplink transmission.
  • the DL-SCH is mapped to a physical downlink shared channel (PDSCH).
  • the Physical Control Format Indicator Channel (PCFICH) informs the terminal 12 of the number of OFDM symbols used for PDCCHs and is transmitted every subframe.
  • PHICH Physical Hybrid ARQ Indicator Channel
  • PHICH Physical Hybrid ARQ Indicator Channel
  • HARQ Hybrid Automatic Repeat reQuest
  • ACK Non-acknowledgement
  • NACK Non-acknowledgement
  • CSI channel status information
  • PMI precoding matrix index
  • PTI precoding type indicator
  • RI rank indication
  • PUSCH Physical Uplink Shared Channel
  • PRACH Physical Random Access Channel
  • the CQI provides information on link adaptive parameters that the terminal 12 can support for a given time.
  • the CQI may indicate a data rate that can be supported by the downlink channel in consideration of characteristics of the receiver of the terminal 12 and signal to interference plus noise ratio (SINR).
  • SINR signal to interference plus noise ratio
  • the base station 11 may determine the modulation (QPSK, 16-QAM, 64-QAM, etc.) and coding rate to be applied to the downlink channel using the CQI.
  • CQI can be generated in several ways.
  • a method of quantizing and feeding back a channel state as it is, a method of calculating a feedback to a signal to interference plus noise ratio (SINR), and a method of notifying a state that is actually applied to a channel such as a modulation coding scheme (MCS) may be used.
  • the MCS includes a modulation scheme, a coding scheme, a coding rate, and the like.
  • PMI provides information about the precoding matrix in the codebook based precoding.
  • PMI is associated with multiple-input multiple-output (MIMO).
  • MIMO multiple-input multiple-output
  • CL MIMO closed loop MIMO
  • RI is information about a rank (ie, number of layers) recommended by the terminal 12. That is, RI represents the number of independent streams used for spatial multiplexing.
  • the RI is fed back only when the terminal operates in the MIMO mode using spatial multiplexing.
  • RI is always associated with one or more CQI feedback. In other words, the fed back CQI is calculated assuming a specific RI value. Since the rank of the channel generally changes slower than the CQI, the RI is fed back fewer times than the CQI.
  • the transmission period of the RI may be a multiple of the CQI / PMI transmission period. RI is given for the entire system band and frequency selective RI feedback is not supported.
  • the wireless communication system 10 may be a multiple antenna system. Multiple antenna systems may be referred to as MIMO systems.
  • the multi-antenna system may be a multiple-input single-output (MISO) system or a single-input single-output (SISO) system or a single-input multiple-output (SIMO) system. May be a system.
  • the MIMO system uses multiple transmit antennas and multiple receive antennas.
  • the MISO system uses multiple transmit antennas and one receive antenna.
  • the SISO system uses one transmit antenna and one receive antenna.
  • the SIMO system uses one transmit antenna and multiple receive antennas.
  • Multiple antenna transmit / receive schemes used for the operation of multiple antenna systems include frequency switched transmit diversity (FST), Space Frequency Block Code (SFBC), Space Time Block Code (STBC), and Cyclic Delay Diversity (CDD).
  • FST frequency switched transmit diversity
  • SFBC Space Frequency Block Code
  • STBC Space Time Block Code
  • CDD Cyclic Delay Diversity
  • TSTD time switched transmit diversity
  • the wireless communication system 10 needs to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like.
  • the process of restoring a transmission signal by compensating for distortion of a signal caused by a sudden change in channel environment is called channel estimation.
  • channel estimation it is also necessary to measure the channel state (channel state) for the cell to which the terminal 12 belongs or other cells.
  • a reference signal (RS) known to each other is used by the terminal 12 and the base station 11 for channel estimation or channel state measurement.
  • the channel information (p. ) can be estimated.
  • the channel estimate estimated using the reference signal p Is Depends on the value, so to get an accurate estimate of You need to converge to zero.
  • the channel can be estimated by minimizing the effects of
  • the reference signal may be allocated to all subcarriers or may be allocated between data subcarriers for transmitting data.
  • a signal of a specific transmission timing is composed of only a reference signal such as a preamble in order to obtain a gain of channel estimation performance.
  • the amount of data transmission can be increased.
  • resource elements used by one antenna to transmit a reference signal are not used by another antenna. This is to avoid interference between antennas.
  • the downlink reference signal includes a channel state information (CSI) reference signal (CSI-RS) and a DMRS.
  • CSI channel state information
  • CSI-RS channel state information reference signal
  • Channel State Information Reference Signal may be used for estimation of channel state information.
  • the CSI-RS is placed in the frequency domain or time domain.
  • CQI, PMI, RI, etc. may be reported from the terminal 12 to the base station 11 as channel state information when necessary through estimation of the channel state using the CSI-RS.
  • transmission mode 0 may be a mode that supports only a single antenna port
  • transmission modes 9 and 10 may be a mode that can support up to eight antenna ports.
  • the definition of the antenna port is as follows.
  • first channel When a first symbol (or signal) is carried over a first channel and a second symbol (or signal) is carried over a second channel, the first channel can be inferred by the second channel.
  • An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed).
  • Each element in the resource grid for antenna port p is called a resource element (RE), and each resource element is identified by an index pair (k, l) in every slot.
  • k is a subcarrier index in the frequency domain
  • l time The symbol index in the region.
  • the resource element represents the smallest frequency-time unit to which the modulation symbol of the data channel or the modulation symbol of the control channel is mapped. If there are M subcarriers on one OFDM symbol, and one slot includes N OFDM symbols, one slot includes a total of M ⁇ N resource elements.
  • antenna ports 0 to 3 may be sequentially mapped to each of four physical antennas.
  • the number of antenna ports and the unique resource grid of each antenna port are determined depending on the reference signal configuration in the cell. For example, when the total number of physical antennas is 64, the number of antenna ports supporting CSI-RS is ⁇ 1, 2, 4, 8 according to the configuration of the CSI-RS and the arrangement of the CSI-RS ports in the physical antenna. , 16, 32, 64 ⁇ , and each antenna port may have a unique pattern for carrying a CSI-RS as shown in FIG. 2 or 3.
  • a unique pattern in which an antenna port carries a CSI-RS or a pattern in which a CSI-RS is mapped to a resource element is called a CSI-RS pattern.
  • FIG. 2 and 3 illustrate a CSI-RS pattern according to an example of the present invention.
  • 2 illustrates an example in which a CSI-RS is mapped to a resource element in the case of a normal cyclic prefix
  • FIG. 3 illustrates an example in which a CSI-RS is mapped to a resource element in the case of an extended CP. It is shown schematically.
  • Rp represents a resource element used for CSI-RS transmission at the antenna port P.
  • R 15 means CSI-RS transmitted from antenna port 15.
  • the CSI-RS pattern is one in which CSI-RSs are mapped to resource elements (2, 5) and (2, 6) of antenna port 15.
  • the CSI-RS pattern is mapped to resource elements (2, 5) and (2, 6) of antenna ports 15 and 16, and that antenna ports 17 and Mapped to resource elements (8, 5) and (8, 6) of 18, mapped to resource elements (3, 5) and (3, 6) of antenna ports 19 and 20, and resource elements of antenna ports 21 and 22 Maps to (9, 5) and (9, 6).
  • each antenna port has a unique CSI-RS pattern.
  • 2 and 3 illustrate a total of eight antenna ports 15 to 22 transmitting CSI-RS in a wireless communication system equipped with eight physical antennas.
  • this is only an example, and in the case of a wireless communication system having 64 physical antennas, up to 64 antenna ports may be supported, and in this case, antenna ports transmitting CSI-RS may be extended to antenna ports 15 to 63.
  • FIG. 4 illustrates a multiple antenna system according to an example of the present invention.
  • the multi-antenna system 400 includes a base station 410 having a plurality of antennas and a terminal 420 having a plurality of antennas.
  • the base station 410 supports a two-dimensional antenna array having eight or more antenna ports.
  • eight or more antenna ports supported by the base station 410 may be a corresponding number of any one of ⁇ 16, 32, 64 ⁇ as an example. That is, the base station 410 may support an antenna port corresponding to a multiple of eight.
  • MU-MIMO multi-user MIMO
  • the base station 410 may transmit the CSI-RS to the terminal 420 for CSI feedback.
  • the base station 410 may transmit the CSI-RS to the terminal 420 in the horizontal antenna port (s) and vertical antenna port (s).
  • PMI1 may correspond to the horizontal antenna port and PMI2 may correspond to the vertical antenna port. That is, PMI1 may be for beamforming in the horizontal direction, and PMI2 may be for beamforming in the vertical direction.
  • PMI1 may correspond to the vertical antenna port, and PMI2 may correspond to the vertical antenna port.
  • PMI1 may correspond to the horizontal antenna port and PMI2 corresponds to the vertical antenna port.
  • the number of antenna ports for CSI-RS transmission in each direction, whether horizontal or vertical, is one of 2, 4, and 8.
  • Codebooks for the two and four antenna ports are designed based on independent spatial channels.
  • the codebook for the eight antenna ports is designed based on the x-polarized antenna configuration. For all antennas, if x polarized antennas are not used, the optimized codebook is redesigned and no co-phasing part is needed.
  • embodiments of the present invention can design a codebook as a combination of discrete fourier transform (DFT) beam and beam selection.
  • DFT discrete fourier transform
  • a new codebook design for a new 8 APs FD MIMO is proposed in consideration of the following criteria.
  • Double beam selection operation for two dimensions by two different PMI indexes through two different PMIs This can be done by using different DFT beam vectors for different columns of the matrix in the codebook. Different DFT beam vectors may be obtained based on two different PMI indexes.
  • a codebook for 8 APs can be designed as follows.
  • the 4 APs DFT beam vector v m and / or v n can be used.
  • a vector v m having a size of 4 is designed in such a manner that the phase is sequentially changed from the first element 1 to the fourth element e j6 ⁇ m / 32 .
  • T means a transpose matrix
  • m is an integer of 0 to 31.
  • the vector v m has a total of 32 beam directions.
  • a codebook design to be described below may be configured by selecting a specific beam direction among the 32 beam directions.
  • each PMI may have 4 bits. Thus only 16 beam directions can be selected in this case.
  • a delta value may be added to a parameter regarding each horizontal and vertical domain of a codebook, which may be represented as shown in Table 1 below.
  • Table 1 shows an example of a codebook for 1-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • W (1) m, n is a codebook for one layer for FD MIMO.
  • v m , v n are the beam vectors of the horizontal domain and the vertical domain, respectively
  • i 1 represents the value of PMI1 (e.g., PMI corresponding to the horizontal domain)
  • i 2 corresponds to PMI2 (e.g., vertical domain) PMI) value.
  • d 1 and d 2 are delta values for beam direction selection for the horizontal domain and the vertical domain, respectively.
  • d 1 and d 2 have a value of 0 or 1.
  • m 2i 1 + d 1
  • n 2i 2 + d 2
  • i 1 and i 2 each have a value of 0 to 15, and thus m and n may each have 32 values. have.
  • the d 1 and d 2 may be determined according to, for example, the following alternatives Alt.
  • the d 1 and the d 2 may be configured through RRC signaling. That is, the d 1 and the d 2 may be changed to semi statically.
  • the d 1 and the d 2 depend on a CSI subframe set.
  • d 1 and d 2 may be determined as in Equations 3 and 4, respectively.
  • C CSI, 0 , C CSI, 1 represent subframe sets, and are configured by a higher layer. For example, if C CSI, 0 , C CSI, 1 is configured by a higher layer, resource-restricted CSI measurements are configured in the terminal.
  • both d 1 and d 2 are set to zero.
  • each subframe set has a different interference condition, and therefore, RI of the two subframe sets If is equal, it is advantageous for the precoding operation of the base station.
  • ICIC Inter-Cell Interference Coordination
  • the d 1 and the d 2 may be determined according to a CSI process.
  • Multiple CSI processes may be configured in a transmission mode (TM) 10, and thus, UEs supporting TM 10 may be configured with two different CSI processes. Therefore, the d 1 and the d 2 can be determined according to each CSI process.
  • TM transmission mode
  • rank 2 codebook For codebooks for two layers (ie rank 2 codebook), the selection of two beam directions is required. That is, two beam directions should be selected for each of the horizontal domain and the vertical domain. In this case, as described above, two PMIs corresponding to the horizontal domain and the vertical domain are used. In order to reduce the interference between these two layers, the direction difference of the two beams should be maximum. Among the 32 directions in total, there are 16 cases in which the beams of each layer have a direction perpendicular to each other (that is, v m (n), v m (n) +16 ). have. Each PMI may have 4 bits to maintain the Rank 2 codebook size defined in the current standard.
  • the rank 2 codebook may be represented as in the following table.
  • Table 2 shows an example of a codebook for two-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • W (2) m, n is a codebook for two layers for FD MIMO.
  • v m , v n are the beam vectors of the horizontal domain and the vertical domain, respectively
  • i 1 represents the value of PMI1 (e.g., PMI corresponding to the horizontal domain)
  • i 2 corresponds to PMI2 (e.g., vertical domain) PMI) value is as described above.
  • the columns of the matrix included in the codebook correspond to the number of layers.
  • rank 3 codebook For codebooks for three layers (ie rank 3 codebook), the selection of three beam directions is required. That is, three beam directions should be selected for each of the horizontal domain and the vertical domain. In this case, as described above, two PMIs corresponding to the horizontal domain and the vertical domain are used. In order to reduce the interference between these three layers, the direction difference of the three beams should be maximum. There are 16 cases in which the direction difference between the three beams is the largest among the 32 directions. Each PMI may have 4 bits to maintain the Rank 3 codebook size defined in the current standard.
  • the rank 3 codebook may be represented as the following table.
  • Table 3 shows an example of a codebook for 3 layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • W (3) m, n is a codebook for three layers for FD MIMO.
  • rank 4 codebook For codebooks for four layers (ie rank 4 codebook), the selection of four beam directions is required. That is, four beam directions should be selected for each of the horizontal domain and the vertical domain. In this case, as described above, two PMIs corresponding to the horizontal domain and the vertical domain are used. In order to reduce the interference between the four layers, there are eight cases where the direction difference of the four beams is maximized. Each PMI may have 3 bits to maintain the Rank 4 codebook size defined in the current standard.
  • the rank 4 codebook may be represented as the following table.
  • Table 4 shows an example of a codebook for 4-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • W (4) m, n is a codebook for four layers for FD MIMO.
  • the selection of five beam directions is required. That is, five beam directions should be selected for each of the horizontal domain and the vertical domain based on the two PMIs.
  • the number of orthogonal beams that can be selected is up to four.
  • an orthogonal structure between columns of the matrix included in the codebook must be maintained.
  • codeword to layer mapping should be considered. Accordingly, the following rules may be followed for rank 5 codebook design.
  • Table 5 (1) Each column of the matrix in the codebook is orthogonal to each other. (2) All possible orthogonal beams are used. (3) Maintain codeword balance. That is, another codeword has the same number of orthogonal beams in both the horizontal and vertical domains.
  • each layer includes at least one beam.
  • codeword layer mapping should be considered important.
  • the following codeword layer mapping may be applied for 5 layer transmission.
  • 5 shows an example of codeword layer mapping for 5 layer transmission.
  • codeword 0 is mapped to layer 1 and layer 2
  • codeword 1 is mapped to layer 3, layer 4, and layer 5.
  • the same number of beams are assigned to codeword 0 and codeword 1. That is, two beams may be shared for each domain (or dimension) of layer 1 and layer 2, and two beams may be shared for each domain (or dimension) for layer 3 and layer 5.
  • a zero vector may be inserted.
  • the rank 5 codebook may be represented as follows.
  • Table 6 shows an example of a codebook for 5-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • W (5) m, n is a codebook for 5 layers for FD MIMO.
  • v m (n) v m (n) +8 , v m (n) +16 , v m (n) +24 , and 0 Vectors can be used.
  • the codebook of Table 6 has a problem that the power applied to the layers are different, so that the rank 5 codebook can be represented as follows so that all the layers have the same power.
  • Table 7 shows another example of a codebook for 5-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • the codebook of Table 7 has a problem that the above-described codeword layer mapping is not considered. If horizontal beamforming is applied to one codeword and vertical beamforming is applied to another codeword, the codebook may be designed. That is, the rank 5 codebook to which domain (or dimension) based codeword division is applied may be represented as follows.
  • Table 8 shows another example of a codebook for 5-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • the rank 5 codebook may be represented as follows.
  • Table 9 shows another example of a codebook for 5-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • rank 6 codebook For codebooks for six layers (ie rank 6 codebook), the selection of six beam directions is required. That is, six beam directions should be selected for each of the horizontal domain and the vertical domain based on the two PMIs.
  • the design rules of Table 5 described above may be applied for the rank 6 codebook.
  • codeword layer mapping may be applied for rank 6 (ie, six layer transmission).
  • 6 shows an example of codeword layer mapping for 6 layer transmission.
  • codeword 0 is mapped to layer 1, layer 2, and layer 3, and codeword 1 is mapped to layer 4, layer 5, and layer 6.
  • the same number of beams are assigned to codeword 0 and codeword 1. That is, layers 1 to 3 may share two beams for each domain (or dimension), and layers 4 to layer 6 may share two beams for each domain (or dimension).
  • layers 1 to 3 may share two beams for each domain (or dimension)
  • layers 4 to layer 6 may share two beams for each domain (or dimension).
  • a zero vector may be inserted.
  • the rank 6 codebook may be represented as follows.
  • Table 10 shows an example of a codebook for six-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • W (6) m, n is a codebook for 6 layers for FD MIMO.
  • the codebook of Table 10 has a problem that the power applied to the layers are different, so that the rank 6 codebook can be represented as follows so that all the layers have the same power.
  • Table 11 shows another example of a codebook for six-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • the rank 6 codebook may be represented as follows.
  • Table 12 shows another example of a codebook for six-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • rank 7 codebook For codebooks for seven layers (ie rank 7 codebook), the selection of seven beam directions is required. That is, seven beam directions should be selected for each of the horizontal domain and the vertical domain based on the two PMIs.
  • the design rules of Table 5 described above may be applied for the rank 7 codebook.
  • codeword layer mapping may be applied for rank 7 (ie, seven layer transmission).
  • codeword 0 is mapped to layer 1, layer 2, and layer 3, and codeword 1 is mapped to layer 4, layer 5, layer 6, and layer 7.
  • layers 1 to 3 may share two beams for each domain (or dimension)
  • layers 4 to layer 7 may share two beams for each domain (or dimension).
  • a zero vector may be inserted.
  • the rank 7 codebook may be represented as follows.
  • Table 13 shows an example of a codebook for 7-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • W (7) m, n is a codebook for 7 layers for FD MIMO.
  • the rank 7 codebook can be represented as follows.
  • Table 14 shows another example of a codebook for 7-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • the rank 7 codebook may be represented as follows.
  • Table 15 shows another example of a codebook for 7-layer CSI reporting using eight antenna ports (numbers 15 to 22).
  • a rank 7 codebook may be represented as follows.
  • Table 16 shows another example of a codebook for 7-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • rank 8 codebook For codebooks for 8 layers (ie, rank 8 codebook), selection of eight beam directions is required. That is, eight beam directions should be selected for each of the horizontal domain and the vertical domain based on the two PMIs.
  • the design rules of Table 5 described above may be applied to the rank 8 codebook.
  • codeword layer mapping may be applied for rank 8 (ie, 8 layer transmission).
  • codeword 0 is mapped to layer 1, layer 2, layer 3, and layer 4, and codeword 1 is mapped to layer 5, layer 6, layer 7, and layer 8.
  • layers 1 to layer 4 may share two beams for each domain (or dimension)
  • layers 5 to layer 8 may share two beams for each domain (or dimension).
  • a zero vector may be inserted.
  • the rank 8 codebook may be represented as follows.
  • Table 17 shows an example of a codebook for 8-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • W (8) m, n is a codebook for 8 layers for FD MIMO.
  • the rank 8 codebook may be represented as follows.
  • Table 18 shows another example of a codebook for 8-layer CSI reporting using 8 antenna ports (numbers 15 to 22).
  • FIG. 9 is an example of an explanatory diagram showing a precoding method in an FD MIMO system according to the present invention.
  • a codebook designed for the antenna configuration as shown in FIG. 5 is used.
  • the terminal transmits a CSI report including a PMI1 corresponding to horizontal APs, a PMI2 corresponding to vertical APs and an RI indicating the number of layers to the base station (S900).
  • PMI1 and PMI2 provide information about the precoding matrix in the codebook based precoding.
  • the RI provides information on rank (ie, number of layers) recommended by the UE.
  • PMI1 may correspond to CSI-RS of APs of the horizontal domain
  • PMI2 may correspond to CSI-RS of APs of the vertical domain.
  • Such dual PMI may support beamforming in the horizontal direction (or domain or dimension) and in the vertical direction (or domain or dimension).
  • the base station determines a codebook according to the number of layers based on the RI, and detects the precoding matrix in the corresponding codebook based on the PMI1 and PMI2 (S910).
  • the base station may use one of the codebooks according to the layers described above in Tables 1 to 4 and Tables 6 to 18.
  • i 1 corresponds to PMI1
  • i 2 corresponds to PMI2 in each table as described above.
  • the base station transmits the precoded data to the terminal based on the detected precoding matrix (S920).
  • FD MIMO operation using up to eight transmit antennas that can be implemented in a next generation mobile communication system
  • it is optimized for two-dimensional beamforming in consideration of codeword layer mapping.
  • codeword layer mapping By providing customized codebooks, system throughput performance can be improved.
  • FIG. 10 is an example of a block diagram illustrating a terminal and a base station according to the present invention.
  • the terminal and the base station according to the present invention can use the antenna configuration as shown in FIG.
  • the base station according to the present invention may use four antenna ports for each of the horizontal direction and the vertical direction.
  • the terminal 1000 includes a terminal memory 1005, a terminal processor 1010, and a terminal transceiver 1020.
  • the terminal memory 1005 is connected to the terminal processor 1010 and stores various information for driving the terminal processor 1010.
  • the terminal transceiver 1020 is connected to the terminal processor 1010 to transmit and receive radio signals.
  • the terminal processor 1010 implements a proposed function, process, and / or method for performing an operation according to the present invention In the above-described embodiments, the operation of the terminal is controlled by the terminal processor 1010. It can be implemented by.
  • the terminal transceiver 1020 receives the CSI-RS from the base station 1050.
  • the terminal transceiver 1020 receives the CSI-RS through APs in the horizontal domain (or direction) of the base station 1050 and APs in the vertical domain (or direction).
  • the terminal processor 1010 includes a channel estimator 1011 and a CSI processor 1012.
  • the channel estimator 1011 performs channel estimation based on the CSI-RS, and the CSI processing unit 1012 is vertical (or horizontal) with the PMI1 corresponding to the horizontal (or vertical) APs based on the result of the channel estimation. Red)
  • the RI indicating the PMI2 and the number of layers corresponding to the APs may be determined.
  • the CSI processor 1012 generates the PMI1, the PMI2, and the RI and sends the generated PMI1, the PMI2, and the RI to the terminal transceiver unit 1020. Then, the terminal transceiver 1020 transmits the CSI report including the PMI1, PMI2, and RI to the base station 1050.
  • PMI1 corresponds to APs of the horizontal domain
  • PMI2 corresponds to APs of the vertical domain.
  • the base station 1050 includes a base station memory 1055, a base station processor 1060, and a base station transceiver 1070.
  • the base station memory 1055 is connected to the base station processor 1060 and stores various information for driving the base station processor 1060.
  • the base station transceiver 1070 is connected to the base station processor 1060 and transmits and / or receives a radio signal.
  • Base station processor 1060 implements the proposed functions, processes and / or methods for performing operations in accordance with the present invention. In the above-described embodiments, the operation of the base station may be implemented by the control of the base station processor 1060.
  • the base station processor 1060 includes a reference signal processor 1061, a CSI processor 1062, and a data processor 1063.
  • the reference signal processor 1061 generates a reference signal including the CSI-RS.
  • the base station transceiver 1070 transmits the reference signal including the CSI-RS to the terminal 1000.
  • the base station transceiver 1070 receives the CSI report from the terminal 1000.
  • the CSI report includes PMI1, PMI2 and RI.
  • PMI1 corresponds to APs of the horizontal domain
  • PMI2 corresponds to APs of the vertical domain.
  • the CSI processor 1062 determines a codebook according to the number of layers based on the RI, and based on the PMI1 and PMI2, The precoding matrix can be detected.
  • a codebook having the following characteristics may be determined or used by the CSI processing unit 1062.
  • each column of the matrix in the codebook is orthogonal to each other.
  • Two double beam selection operations for two dimensions are performed through two different PMIs. This can be done by using different DFT beam vectors for different columns of the matrix in the codebook. Different DFT beam vectors may be obtained based on two different PMI indexes.
  • the coping operation is eliminated.
  • the coping operation is replaced by the beam selection operation.
  • the CSI processing unit 1062 may use one of the codebooks according to the layers described above in Tables 1 to 4 and Tables 6 to 18.
  • i 1 corresponds to PMI1
  • i 2 corresponds to PMI2 in each table as described above.
  • the data processor 1063 generates precoded data based on the detected precoding matrix, and transmits the precoded data to the terminal 1000 through the base station transceiver 1070.
  • the processor may include an application-specific integrated circuit (ASIC), another chipset, logic circuit and / or data processing device.
  • the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device.
  • the transceiver may include a baseband circuit for processing a radio signal.
  • the technique according to the present invention may be implemented as a module (process, function, etc.) for performing a corresponding function.
  • the module may be stored in memory and executed by a processor.
  • the memory may be internal or external to the processor and may be coupled to the processor by various well known means.

Abstract

La présente invention concerne un procédé pour supporter un système FD-MIMO (full dimension (FD) à entrées multiples et à sorties multiples (MIMO) dans un système d'antennes multiples dans lequel un domaine horizontal et un domaine vertical comprennent chacun quatre ports d'antennes (AP). Le procédé comprend un livre de codes ayant des propriétés unitaires. Le livre de codes est basé sur un vecteur de faisceau DFT. Il utilise tous les faisceaux orthogonaux possibles, et comprend le même nombre de faisceaux orthogonaux entre les mots de code, dans le cadre d'un mappage de couche de mots de code.
PCT/KR2014/011771 2013-12-03 2014-12-03 Procédé de rétroaction de csi, et appareil d'un système d'antennes multiples WO2015084051A1 (fr)

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CN111836383A (zh) * 2020-05-19 2020-10-27 东南大学 基于波束域信道的scma码本调度方法
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KR20160149657A (ko) * 2015-06-19 2016-12-28 한국과학기술원 빔 공간 다중 안테나 시스템에 기반한 빔 변복조 방법 및 장치
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CN112640324A (zh) * 2018-06-29 2021-04-09 弗劳恩霍夫应用研究促进协会 具有适应于天线阵列的任意天线响应的波束成形系数的天线阵列码本
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