WO2017166281A1 - 一种预编码矩阵指示的反馈方法及装置 - Google Patents

一种预编码矩阵指示的反馈方法及装置 Download PDF

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Publication number
WO2017166281A1
WO2017166281A1 PCT/CN2016/078298 CN2016078298W WO2017166281A1 WO 2017166281 A1 WO2017166281 A1 WO 2017166281A1 CN 2016078298 W CN2016078298 W CN 2016078298W WO 2017166281 A1 WO2017166281 A1 WO 2017166281A1
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Prior art keywords
precoding matrix
indication
column
terminal device
matrix
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PCT/CN2016/078298
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English (en)
French (fr)
Inventor
张瑞齐
刘建琴
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华为技术有限公司
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Priority to EP16896061.5A priority Critical patent/EP3435574A4/en
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to BR112018070175A priority patent/BR112018070175A2/pt
Priority to KR1020187031254A priority patent/KR102150316B1/ko
Priority to CN201910306923.2A priority patent/CN109951220B/zh
Priority to CA3019607A priority patent/CA3019607C/en
Priority to PCT/CN2016/078298 priority patent/WO2017166281A1/zh
Priority to CN201910306669.6A priority patent/CN110034797B/zh
Priority to CN201680084105.7A priority patent/CN109075904B/zh
Priority to JP2018551761A priority patent/JP6750926B2/ja
Publication of WO2017166281A1 publication Critical patent/WO2017166281A1/zh
Priority to US16/148,296 priority patent/US10419090B2/en
Priority to US16/248,344 priority patent/US10454546B2/en
Priority to US16/583,043 priority patent/US10897291B2/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
    • 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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0486—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking channel rank into account
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0645—Variable feedback
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0658—Feedback reduction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
    • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/042—Public Land Mobile systems, e.g. cellular systems

Definitions

  • the present application relates to the field of mobile communications, and more particularly to multi-antenna technology in wireless communication systems.
  • LTE Long term evolution
  • MIMO multiple input and multiple output
  • the transmitting end can use precoding technology to process the data, thereby improving the signal transmission quality or rate.
  • the transmitting end may be a base station or a terminal device.
  • a base station In an LTE system, a base station generally uses a precoding matrix indicator (PMI) to obtain a precoding matrix.
  • PMI precoding matrix indicator
  • the set of precoding matrices used is often referred to as a codebook or set of codebooks.
  • Each precoding matrix in a codebook or codebook set may also be referred to as a codeword.
  • the terminal device quantizes channel state information (CSI) and feeds back to the base station, and the base station determines the precoding matrix according to the CSI.
  • the CSI information fed back by the existing LTE system includes a rank indication (RI), a PMI, and the like, where the RI is used to indicate the number of data spatial multiplexing.
  • the PMI is used to indicate the precoding matrix.
  • the first level of feedback indicates a vector group containing 4 vectors that can be used for subsequent processing.
  • the second level feedback selects one of the four vectors, and the selected vector can be used for data precoding.
  • the first stage feedback has a long period/wideband characteristic
  • the second stage feedback has a short period/subband characteristic.
  • Figure 1 shows a schematic of a two-dimensional antenna array.
  • the antenna ports are divided into 45° polarization and -45° polarization.
  • N 1 antenna ports for one polarization direction, there are N 1 antenna ports in the horizontal direction and N 2 antenna ports in the vertical direction.
  • the vector group in the first level feedback needs to include more vectors. For example, 32 antenna ports will contain 16 antenna ports in each polarization direction. If the vector group of the first-stage feedback in the system of the 32-antenna port and the vector group of the first-stage feedback in the system of the 16-antenna port are to have the same coverage airspace, the first-level feedback in the system of the 32-antenna port Vector group needs To include 16 column vectors. As shown in Figure 2a, Figure 2b.
  • the current codebook feedback mechanism is used in the case of the 32-antenna port, that is, the vector group of the first-level feedback contains 4 vectors, it will inevitably affect the coverage bandwidth, resulting in a decrease in the performance of the codebook.
  • the second-level feedback needs to be selected among the 16 vectors, which increases the number of bits of the second-level feedback, thereby increasing the system overhead of the terminal device.
  • the present application describes a feedback method and apparatus for precoding matrix indication to minimize the system overhead of the terminal device while satisfying the system performance requirements as much as possible.
  • a method of determining a precoding matrix comprising:
  • the precoding matrix W corresponds to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, and the first precoding matrix indication corresponds to the first precoding matrix W 1 ,
  • the second precoding matrix indication corresponds to the second precoding matrix W 2 , and the third precoding matrix indication corresponds to the third precoding matrix W 3 .
  • the terminal device sends the rank indication, the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication.
  • W 1 of the set of columns in each column comprises 2 W 1 ⁇ W, expressed in W 1 is selected from column 2K column vector as a result of the W 1 ⁇ W 2.
  • the number of vectors in the subsequent candidate vector set is reduced, thereby reducing the computational complexity of the subsequent processing, and reducing the number of bits of the feedback PMI of the candidate for vector selection.
  • a feedback method for precoding matrix indication comprising:
  • the base station determines, in the precoding matrix set corresponding to the rank indication, the second precoding matrix indication and the third precoding matrix indication, determining the precoding matrix W according to the first precoding matrix indication,
  • the first precoding matrix indication corresponds to the first precoding matrix W 1
  • the second precoding matrix indication corresponds to the second precoding matrix W 2
  • the third precoding matrix indication corresponds to The third precoding matrix W 3 .
  • an embodiment of the present invention provides a terminal device, where the terminal device has a function of implementing a behavior of a terminal device in the design of the foregoing method.
  • the functions may be implemented by hardware or by corresponding software implemented by hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the modules can be software and/or hardware.
  • the terminal device includes:
  • the precoding matrix W corresponds to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, and the first precoding matrix indication corresponds to the first precoding matrix W 1 ,
  • the second precoding matrix indication corresponds to the second precoding matrix W 2 , and the third precoding matrix indication corresponds to the third precoding matrix W 3 ;
  • a sending unit configured to send the rank indication, the first precoding matrix indication, and the second pre An encoding matrix indication and the third precoding matrix indication.
  • the terminal device further includes: a receiving unit, configured to receive configuration parameters sent by the base station.
  • an embodiment of the present invention provides a base station, where the base station has a function of implementing a behavior of a base station in the foregoing method.
  • the functions may be implemented by hardware or by corresponding software implemented by hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the base station includes:
  • a receiving unit configured to receive a rank indication sent by the terminal device, the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication;
  • a processing unit configured to: in the precoding matrix set corresponding to the rank indication, determine, according to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, determine a precoding matrix W,
  • the first precoding matrix indication corresponds to the first precoding matrix W 1
  • the second precoding matrix indication corresponds to the second precoding matrix W 2
  • the third precoding matrix indication corresponds to The third precoding matrix W 3 .
  • the base station further includes: a sending unit, configured to send configuration parameters.
  • W 2 is satisfied Where X 2 is an M row and K column matrix, and any column of X 2 is represented as e p , e p is a column vector of M ⁇ 1, the pth element is 1, the remaining elements are 0, and p is 1 to M. Integer.
  • W 1 is satisfied Where X 1 is a matrix of N t /2 rows and M columns, v o is a column vector containing N t /2 elements, and o is an integer from 0 to M-1;
  • the first precoding matrix indicates that the corresponding frequency domain resource is a downlink system bandwidth of the terminal device, where the downlink system bandwidth includes A first subband and B second subbands.
  • A, B is a positive integer greater than 1, and A is less than or equal to B.
  • the second precoding matrix indicates that the corresponding frequency domain resource is one of the A first subbands
  • the third precoding matrix indicates that the corresponding frequency domain resource is in the B second subbands.
  • the number of column vectors in the vector group corresponding to the first sub-band is smaller than the number of vectors in the vector group corresponding to the system bandwidth, thereby reducing the number of vectors to be searched for vector selection on the second sub-band, and may be reduced. Small in the second sub-band feedback the selected vector indicates the number of bits required.
  • the frequency domain resource of the at least one first subband of the A first subbands is the same as the frequency domain resource of the at least two second subbands of the B second subbands.
  • the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indicate that the corresponding frequency domain resource is a downlink system bandwidth of the terminal device.
  • the transmission period indicated by the first precoding matrix is P 1
  • the transmission period indicated by the second precoding matrix is P 2
  • the third transmission cycle precoding matrix indicator is P 3, wherein , P 1 is greater than or equal to P 2
  • P 2 is greater than or equal to P 3 .
  • the sending period P 1 , P 2 , and P 3 are sent by the base station to the terminal device by using Radio Resource Control (RRC) signaling.
  • RRC Radio Resource Control
  • Different precoding matrices indicate that different transmission periods are configured, and they are used to correspond to different characteristics of the channel. Some corresponding channels change faster parts over time, and some correspond to slower parts of the channel change over time.
  • the first precoding matrix indicates the portion of the corresponding channel that transforms the slowest time
  • the second precoding matrix indicates the portion of the corresponding channel that changes slowly with time
  • the third precoding matrix indicates the portion of the corresponding channel that changes faster with time.
  • P 1 , P 2 , and P 3 can be configured to save the number of bits of the feedback PMI.
  • the T column vectors of the 2K column vectors in the W 2 are indicated by the first precoding matrix indication, where T is an integer greater than or equal to 2, and T is less than K.
  • Removing 2K-T column vectors in the T column vectors in the W 2 is indicated by the T column vectors and the second precoding matrix indication. Doing so reduces the number of bits required to feed back the second precoding matrix indication.
  • the W 2K column vector indicated by 2 and the configuration parameters sent second precoding matrix indicated by the base station. Doing so reduces the number of bits required to feed back the second precoding matrix indication.
  • the configuration parameter is used to indicate the optional column vector set of the W 1 , and the selectable column vector set includes J column vectors, where J satisfies 2K ⁇ J ⁇ 2M.
  • the configuration parameter is a configuration parameter that is sent by the base station to the terminal device by using RRC signaling.
  • X 2 in the W 2 is satisfied.
  • X 3 is a matrix of M 1 rows and K 1 columns
  • X 4 is a matrix of M 2 rows and K 2 columns, Represents Kronecker.
  • Any column of X 3 is represented as e i , and e i is a column vector of M 1 ⁇ 1, the i-th element is 1, the remaining elements are 0, and the value of i is an integer from 1 to M 1 .
  • Any column of X 4 is represented as e j , and e j is a column vector of M 2 ⁇ 1, the jth element is 1, the remaining elements are 0, and the value of j is an integer from 1 to M 2 .
  • the transmitting unit may be a transmitter
  • the receiving unit may be a receiver
  • the processing unit may be a processor
  • the embodiment of the invention further provides a system, which comprises the terminal device and the base station in the above embodiment.
  • the feedback (or transmission) indicated by the first precoding matrix may be regarded as the first level feedback
  • the feedback indicated by the second precoding matrix may be regarded as the second level feedback
  • the feedback indicated by the third precoding matrix may be Think it is the third level of feedback.
  • the feedback indicated by the precoding matrix in the solution provided by the present application is divided into three levels.
  • the second level of feedback is used to indicate a partial vector in the vector group indicated by the first level of feedback. Due to the reduction of the number of vectors to be selected, the system overhead of calculating the third-level feedback of the terminal is reduced, and the number of bits required for the third-level feedback is reduced, and the system performance and the terminal device feedback overhead are realized. a better balance.
  • 1 is a schematic diagram of a two-dimensional antenna array
  • 2a is a schematic diagram of an 8 antenna port beam group coverage space
  • 2b is a schematic diagram of a 32-antenna port beam group coverage space
  • FIG. 3 is a schematic flowchart of a method for feeding back a precoding matrix indication according to an embodiment of the present invention
  • FIG. 4 is a schematic diagram of a correspondence between multipath and a vector group
  • Figure 5 is a schematic view of the first sub-band and the second sub-band
  • FIG. 6 is a schematic block diagram of a terminal device according to an embodiment of the present invention.
  • FIG. 7 is a schematic block diagram of a base station according to an embodiment of the present invention.
  • FIG. 8 is another schematic block diagram of a terminal device according to another embodiment of the present invention.
  • FIG. 9 is another schematic block diagram of a base station according to another embodiment of the present invention.
  • the network architecture and the service scenario described in the embodiments of the present invention are for a clearer description of the present disclosure.
  • the technical solutions of the embodiments of the present invention are not limited to the technical solutions provided by the embodiments of the present invention.
  • the technical solutions provided by the embodiments of the present invention may be known as the evolution of the network architecture and the appearance of new service scenarios. The same applies to similar technical issues.
  • LTE long term evolution
  • FDD frequency division duplex
  • TDD Time Division Duplex
  • D2D device to device
  • a terminal equipment may be referred to as a terminal, or may be a user equipment (UE), a mobile station (MS), or a mobile terminal ( Mobile terminal), etc.
  • the terminal device can communicate with one or more core networks via a Radio Access Network (RAN), for example, the terminal device can be a mobile phone (or "cellular" phone) or have The computer or the like of the mobile terminal, for example, the terminal device may also be a portable, pocket-sized, handheld, computer-integrated or in-vehicle mobile device that exchanges voice and/or data with the wireless access network.
  • RAN Radio Access Network
  • the base station may be an evolved base station (evolutional node B, referred to as “eNB or e-NodeB”) in LTE, or may be another base station, or may be a relay or the like.
  • eNB evolved base station
  • the D2D communication may also be a device in the D2D communication, and the present invention is not limited. However, for convenience of description, the following embodiments will be described by taking an eNB as an example.
  • FIG. 3 shows a schematic flow chart of a method for determining a precoding matrix according to an embodiment of the present invention. As shown in FIG. 3, the method includes:
  • step 101 the terminal device determines a rank indication.
  • the value of one rank corresponds to a rank indication.
  • the terminal device sends a rank indication to the base station to indicate the number of downlink data that the terminal device desires to perform spatial multiplexing.
  • the value of the rank ranges from 1 to 8, and the rank indication is represented by 3 bits.
  • the rank indication is 000, the rank is 1; when the rank indication is 001, the rank is 2, and so on.
  • the rank takes a certain value, there is a value of the rank indication corresponding to the rank.
  • the terminal device may determine, according to information such as CSI, a number indicating data spatial multiplexing, that is, a rank.
  • the base station sends a cell-specific reference signal (CRS) to the terminal device, or sends a channel state information reference signal (channel state information). Reference signal, CSI-RS).
  • CRS cell-specific reference signal
  • CSI-RS channel state information reference signal
  • the terminal device obtains the downlink channel estimation and the downlink interference estimation according to the CRS, or the CSI-RS, and then determines the number of downlink data transmission spatial multiplexing desired by the terminal device, that is, the rank, according to the two. It should be understood that the terminal device may determine the rank by a method well known to those skilled in the art, and for brevity, no further details are provided herein.
  • Step 102 Determine a precoding matrix in a precoding matrix set corresponding to the rank indication.
  • the terminal device may determine, in a precoding set corresponding to the rank indication, a precoding matrix used by the terminal device to expect the base station eNB to transmit downlink data, based on a reference signal such as a CSI-RS.
  • Step 103 Determine a first precoding matrix indication, a second precoding matrix indication, and a third precoding matrix indication for indicating the precoding matrix.
  • each precoding matrix is indicated by a first precoding matrix indication, a second precoding matrix indication, and a third precoding matrix indication.
  • the first precoding matrix indication, the second precoding matrix indication, the third precoding matrix indication, and the precoding matrix W have a one-to-one correspondence.
  • the first precoding matrix indicates that the second precoding matrix indicates that the third precoding matrix indication is represented by two bits, respectively, and a total of six bits represent the precoding matrix indication.
  • Each precoding matrix W corresponds to three precoding matrix indications.
  • the value of the first precoding matrix is 00
  • the value of the second precoding matrix is 00
  • the value of the third precoding matrix is 00.
  • the precoding matrix of the 6 bits is indicated as 000000, corresponding to a precoding matrix W.
  • the 6-bit precoding matrix is indicated as 000001, it corresponds to another precoding matrix W.
  • each precoding matrix W has a one-to-one correspondence with the precoding matrix, which is equivalent to knowing the value indicated by the precoding matrix, and determines the corresponding precoding matrix.
  • Step 104 The terminal device sends the rank indication and the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication to the base station.
  • a rank indication is sent to the base station, and a precoding matrix indication (the first precoding matrix indication, the second precoding) is used to indicate the precoding matrix.
  • Matrix indication, third precoding matrix indication is used to indicate the precoding matrix.
  • the base station may configure the terminal device to feed back the precoding matrix indication on the PUSCH or feed back the precoding matrix indication on the physical uplink control channel (PUCCH).
  • PUCCH physical uplink control channel
  • the rank indication and the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication where the rank indication may be sent before the three precoding matrix indications are sent; A portion of the encoding indication is sent together; it can also be sent with all of the three precoding indications. There is no sequential restriction on the transmission of the rank indication and the precoding matrix indication.
  • the base station receives the rank indication sent by the terminal device and the precoding matrix indication.
  • the base station receives a rank indication and a first precoding matrix indication, a second precoding matrix indication, and a third precoding matrix indication.
  • the rank indication may be received prior to the 3 precoding matrix indications; it may also be received with a portion of the 3 precoding indications; it may also be received with all of the three precoding indications. There is no sequential restriction on the reception of the rank indication and the precoding matrix indication.
  • step 106 in the codebook set corresponding to the rank indication, determining precoding according to the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication matrix.
  • the base station transmits data according to the precoding matrix.
  • the base station sends data to the terminal device according to the precoding matrix determined in step 106.
  • the base station can send data to the terminal device on a physical downlink shared channel (PDSCH).
  • PDSCH physical downlink shared channel
  • the precoding matrix used by the base station when transmitting data may be a precoding matrix indicated by the terminal device to indicate a corresponding precoding matrix.
  • another precoding matrix obtained may be obtained by transforming according to the precoding matrix, for example, considering a zero-forcing algorithm at the transmitting end between multi-user MIMO.
  • the precoding matrix W corresponds to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, and the first precoding matrix indication corresponds to the first precoding matrix W 1 ,
  • the second precoding matrix indication corresponds to the second precoding matrix W 2 , and the third precoding matrix indication corresponds to the third precoding matrix W 3 .
  • W 1 of the set of columns in each column comprises 2 W 1 ⁇ W, expressed in W 1 is selected from column 2K column vector as a result of the W 1 ⁇ W 2.
  • the number of vectors in the subsequent candidate vector set is reduced, thereby reducing the computational complexity of the subsequent processing, and reducing the number of bits of the feedback PMI of the candidate for vector selection.
  • W 2 is used to select the column vector in W 1 , so that the number of selectable vector sets in W 3 is reduced, the number of bits required for feedback W 3 is reduced, and the computational complexity is also reduced.
  • the formed beam is also finer and thinner, and it is even possible that one beam can cover only one path in the multipath channel.
  • the terminal device In order to capture more channel paths, it is a good way for the terminal device to select and feed back multiple vector groups for base station precoding, where the size of the vector group can contain 4 vectors, or smaller, such as containing 2 vectors. .
  • N 1 is the number of antenna ports in one polarization direction (45° polarization or -45° polarization) in the first dimension direction
  • N 2 is the number of antenna ports in one polarization direction in the second dimension direction
  • N 1 ⁇ N 2 N t /2.
  • the first dimension direction may be a horizontal dimension direction (or a vertical dimension direction)
  • the second dimension direction may be a vertical dimension direction (or a horizontal dimension direction).
  • W 1 contains 16 vectors to cover the entire system bandwidth. E.g, Since W 1 is a block diagonal matrix, and in W 1 , the two diagonal matrices are the same.
  • the number of vectors included in W 1 refers to the number of column vectors contained in X 1 and does not refer to the number of column vectors in W 1 .
  • the number of column vectors in W 1 is twice the number of column vectors included in X 1 .
  • the column vector in X 1 acts as a beamforming when applied to an antenna port in a polarization direction.
  • each column in X 1 is a DFT vector (DFT, Discrete Fourier Transform,). Therefore, each column vector in X 1 can be thought of as a direction vector or a beam vector.
  • the DFT vector refers to the precoding matrix of Tx1, which usually has the form shown by the following equation:
  • the superscript T indicates matrix transposition.
  • One diagonal block X 1 in W 1 is used for one polarization direction, and the other diagonal block X 1 is used for the other polarization direction.
  • the antenna ports are arranged in the horizontal direction, and there are 16 antenna ports in one polarization direction. Then the number of rows of the matrix X 1 is 16.
  • W 1 contains 16 vectors, which is equivalent to X 1 with 16 columns.
  • each column of X 1 can be a DFT vector.
  • Each of the four vectors in X 1 is grouped into one vector group, and a total of four vector groups. For example, X of 1 to 4 as a first vector group; the fifth to eight X 1 as a second vector; 9th to 12 X 1 is set as a third vector; The 13th to 16th columns of X 1 are taken as the fourth vector group.
  • the 16 vectors in W 1 contain vectors used by the terminal device to expect base station precoding for a long period of time. But in fact, at some point, not every vector in the vector group can be used.
  • the path to the base station antenna port has two strong paths.
  • the first strong path when the base station uses the vector in the first vector group for precoding, the generated beam can be in the direction of the main lobe.
  • the first strong path is aligned; when the base station performs precoding using the vector in the fourth vector group, the generated beam can be aligned with the second strong path in the direction of the main lobe. As shown in Figure 4.
  • the terminal device needs to send a first precoding matrix W corresponding to an indication (including 16 beams vectors), and further a second feedback precoding matrix indicator or a plurality of vectors selected in the group of W 1 .
  • the terminal device sends an indication of the first vector group and the fourth vector group to the base station.
  • the terminal also sends a vector group 1+k orthogonal to the vector group 1 and a vector group 4+k' orthogonal to the vector group 4 to the base station, wherein the vector of the vector group numbered 1+k is The vector of the vector group numbered 1+k' is [v 5+k' v 6+k' v 7+k' v 8+k' ].
  • Y [v 1 ... v 8 v 1+k ... v 4+k v 5+k' ... v 8+k' ].
  • W 2 is satisfied Where X 2 is an M row and K column matrix, and any column of X 2 is represented as e p , e p is a column vector of M ⁇ 1, the pth element is 1, the remaining elements are 0, and p is 1 to M. Integer.
  • W 1 is satisfied.
  • X 1 is a matrix of N t /2 rows and M columns
  • X 1 [v 0 ... v M-1 ]
  • v o is a column vector containing N t /2 elements, and o is an integer of 0 to M-1 ;
  • W 1 can be expressed as
  • L 1 represents the number of column vectors in the first direction in X 1 of W 1 .
  • Indicates the nth precoding vector in the second direction, n 0, 1, . . . , L 2 -1.
  • the number of column vectors in the second direction in X 1 of W 1 is represented by L 2 .
  • Q 1 and Q 2 are generation parameters for generating the above column vectors, and both are positive integers.
  • the first direction may be a horizontal direction (or a vertical direction)
  • the second direction may be a vertical direction (or a horizontal direction).
  • e i denotes a column vector of M ⁇ 1, where the i-th element is 1, and the remaining elements are 0;
  • M L 1 ⁇ L 2 .
  • the e l effect in W 3 is a vector indicating precoding, and the ⁇ n effect is phase weighting between two sets of polarized antennas. Since the first N t /2 lines of the precoding matrix W correspond to the precoding weights of the antenna ports of one polarization direction, the latter N t /2 lines correspond to the precoding weights of the antenna ports of the other polarization direction.
  • the first precoding matrix indicates that the corresponding frequency domain resource is a downlink system bandwidth of the terminal device
  • the downlink system bandwidth includes A first subbands, B second subbands, A, B are positive integers greater than 1, and A is less than or equal to B;
  • the second precoding matrix indicates that the corresponding frequency domain resource is one of the A first subbands
  • the third precoding matrix indicates that the corresponding frequency domain resource is in the B second subbands.
  • the downlink system bandwidth may be the downlink system bandwidth of one carrier. For example, if there is only one carrier in the downlink, the downlink system bandwidth is the downlink system bandwidth of the carrier. In the carrier aggregation scenario, if there are multiple carriers in the downlink, the downlink system bandwidth is the downlink system bandwidth of the carrier corresponding to the CSI corresponding to the terminal device. For example, there are two carriers in the downlink, which are carrier 1 and carrier 2. The terminal device currently feeds back the CSI of carrier 1, and the downlink system bandwidth is the downlink system bandwidth of carrier 1.
  • the terminal device reports a second precoding matrix indication for each of the first subbands, and reports a third precoding matrix indication for each of the second subbands.
  • the frequency domain resource of the at least one first subband of the A first subbands and at least two of the B second subbands are the same.
  • the entire system bandwidth is divided into A first sub-bands, each first sub-band comprising S second sub-bands.
  • the terminal device transmits a second precoding matrix indication to the base station for the entire system bandwidth.
  • the terminal device sends a first precoding indication for the system bandwidth; the terminal device sends a second precoding matrix indication for each first subband, and the terminal device sends a third precoding matrix indication for each second subband.
  • the terminal device needs to select a second precoding matrix indication for each first subband, wherein the second precoding matrix indication is used to select 2K column vectors in the first precoding matrix for the subband.
  • each first sub-band carries four second sub-bands.
  • W 1 contains 16 beam vectors
  • X 1 there are 16 columns in X 1 corresponding to 16 beam vectors.
  • the diagonal matrix of W 1 is the Kronecker product of 8 horizontal directions and 2 vertical direction vectors, for a total of 16 beam vectors.
  • the beam vector in W 1 is the Kronecker product of 4 horizontal directions and 4 vertical direction vectors, and is also 16 beams. vector.
  • the vector in W 1 is divided into several vector groups, each of which contains 4 or 8 beam vectors.
  • W 1 contains 16 beam vectors, and 16 beam vector numbers are denoted as 1, 2, ... 16 .
  • Eight beams are used as one beam vector group, in which four beam vectors are overlapped with each other between two adjacent beam vector groups, so 16 beam vectors can be divided into three beam vector groups.
  • the first beam vector group contains beam vectors numbered 1 to 8
  • the second beam vector group contains beam vectors numbered 5 to 12
  • the third beam vector group contains beam vectors numbered 9 to 16.
  • the terminal device indicates which of the selected beam vector groups is indicated by the second precoding matrix. It is equivalent to determining W 2 .
  • W 2 for the third precoding indication, which of the beam vectors can be used for precoding can be selected with 3 bits.
  • W 1 includes 16 beam vectors, which are divided into 4 groups of 4 beam vectors, the first beam vector group includes beam vectors numbered 1 to 4, and the second beam vector group includes number 5 Beam vector to 8; third beam vector group contains beam vectors numbered 9 to 12, and fourth beam vector group contains beam vectors numbered 13 to 16. There is no overlapping beam vector between adjacent groups, and the terminal device indicates which beam vector group is selected by the second precoding matrix.
  • the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indicate that the corresponding frequency domain resource is The downlink system bandwidth of the terminal device.
  • This embodiment corresponds to the wideband feedback indicated by the precoding matrix.
  • the wideband feedback indicated by the precoding matrix refers to the precoding matrix of the feedback indicating that the corresponding frequency domain resource is the entire system bandwidth.
  • the sending period indicated by the first precoding matrix is P 1
  • the sending period indicated by the second precoding matrix is P 2
  • the transmission period indicated by the three precoding matrix is P 3 , where P 1 is greater than or equal to P 2
  • P 2 is greater than or equal to P 3 .
  • the sending period P 1 , P 2 , and P 3 are sent by the base station to the terminal device by using Radio Resource Control (RRC) signaling.
  • RRC Radio Resource Control
  • Different precoding matrices indicate that different transmission periods are configured, and they are used to correspond to different characteristics of the channel. Some corresponding channels change faster parts over time, and some correspond to slower parts of the channel change over time.
  • the first precoding matrix indicates the portion of the corresponding channel that transforms the slowest time
  • the second precoding matrix indicates the portion of the corresponding channel that changes slowly with time
  • the third precoding matrix indicates the portion of the corresponding channel that changes faster with time.
  • P 1 , P 2 , and P 3 can be configured to save the number of bits of the feedback PMI.
  • the length of one subframe is 1 millisecond, which is also the length of a transmission time interval (TTI).
  • TTI refers to the length of an independent decoded transmission in a wireless link.
  • the terminal device feeds back a precoding matrix indication on the PUCCH.
  • a channel quality indication (CQI) and a third precoding matrix indicate that the PUCCH is reported in one subframe.
  • the rank indication and the first precoding matrix indicate that the PUCCH is reported in one subframe.
  • the reporting period indicated by the rank indication and the first precoding matrix is P 1 ; the reporting period indicated by the second precoding matrix is P 2 ; and the reporting period indicated by the channel quality indicator and the third precoding matrix is P 3 .
  • the RI is reported together with a precoding type indication (PTI) first precoding matrix indication, and there are also three reporting periods, P 1 , P 2 , P 3 .
  • PTI precoding type indication
  • terminal device RI reporting on PUCCH, PTI and a first precoding matrix indicator.
  • Broadband CQI reporting refers to the frequency domain resource corresponding to the feedback CQI is the entire system bandwidth.
  • T column vectors of 2K column vectors in W 2 are indicated by the first precoding matrix indication, and T is an integer greater than or equal to 2. And T is less than K, and removing 2K-T column vectors in the T column vectors in the W 2 is indicated by the T column vectors and the second precoding matrix indication.
  • the 16 beam vectors are determined to be [v 1 ... v 16 ], where [v 1 v 2 v 3 v 4 ] is a mandatory beam vector, and the second precoding matrix is not needed.
  • the second precoding matrix indication is only used to indicate another vector group, such as l to indicate the relationship between the second vector group and the first vector group.
  • the second vector group may also be directly indicated.
  • the first precoding matrix indicates that four vector groups are corresponding, wherein the first vector group is a mandatory vector, and the second precoding matrix indicates a vector of another selected one. group.
  • the plurality of sets of vector ratios of W 1 need to be selected by the second precoding matrix indication, the second precoding matrix indicates that the vector group requiring the indication is reduced, and the number of bits of the feedback is further reduced.
  • the second precoding matrix reduces the number of bits required to indicate a vector group from indicating two vector groups to indicating a vector group.
  • the W 2K column vector indicated by 2 and the configuration parameters sent second precoding matrix indicated by the base station optionally one embodiment, the W 2K column vector indicated by 2 and the configuration parameters sent second precoding matrix indicated by the base station.
  • W 1 contains 16 beam vectors, divided into 4 groups of 4 vectors each, the first vector group contains beam vectors numbered 1 to 4, and the second vector group contains beam vectors numbered 5 to 8.
  • the third vector group contains beam vectors numbered 9 to 12, and the fourth vector group contains beam vectors numbered 13 to 16.
  • the terminal device sends an indication of the first vector group and the fourth vector group to the base station through the second precoding matrix indication, and a total of eight column vectors.
  • the selected vector group may be further downsampled according to the configuration parameter. For example, when the configuration parameter is 1, the first to fourth vectors are selected from the eight vectors.
  • the configuration parameter may be that the base station sends the RRC signaling to the terminal device.
  • the configuration parameter is used to indicate the selectable column vector set of the W 1 , and the selectable column vector set includes J column vectors, J Satisfy 2K ⁇ J ⁇ 2M.
  • the second precoding indicates whether the first beam vector group or the third beam vector group is further selected for subsequent processing. By configuring the parameters, the number of bits that feed back the second precoding indication is reduced.
  • X 1 in the W 1 is satisfied.
  • X 2 in the W 2 is satisfied.
  • X 3 is a matrix of M 1 rows and K 1 columns
  • X 4 is a matrix of M 2 rows and K 2 columns, Represents Kronecker.
  • Any column of X 3 is represented as e i , and e i is a column vector of M 1 ⁇ 1, the i-th element is 1, the remaining elements are 0, and the value of i is an integer from 1 to M 1 .
  • Any column of X 4 is represented as e j , and e j is a column vector of M 2 ⁇ 1, the jth element is 1, the remaining elements are 0, and the value of j is an integer from 1 to M 2 .
  • steps 102, 103 may be determined in the order without prioritization. Since the precoding matrix used by the base station is determined by the terminal device, the corresponding precoding matrix indication is also determined.
  • Step 101 and steps 102, 103, step 101 may be before steps 102, 103; or steps 101, 102, 103 may be performed simultaneously.
  • the received signal model of the UE is
  • y is the received signal vector
  • H is the channel matrix
  • W is the precoding matrix
  • s is the transmitted symbol vector
  • n is the interference plus noise.
  • the terminal device traverses all ranks and all coding matrices corresponding to each rank, and calculates the channel capacity obtained by precoding each precoding matrix. For each precoding matrix, one channel capacity is obtained.
  • the channel capacity can be the number of bits that the sender can correctly transmit.
  • a precoding matrix corresponding to the largest channel capacity is obtained, and a rank corresponding to the precoding matrix.
  • the terminal device indicates the rank corresponding to the precoding matrix, and the precoding matrix corresponding to the precoding matrix is sent to the base station.
  • the precoding matrix may be obtained by using a precoding matrix indication. For example, traversing the precoding matrix indication, when traversing to a certain precoding matrix indication, obtaining a precoding matrix according to the precoding matrix indication, and calculating a channel capacity according to the precoding matrix. The precoding matrix may also be traversed directly. After the precoding matrix that maximizes the channel capacity is selected, the precoding matrix indication is obtained according to the one-to-one correspondence between the precoding matrix and the precoding matrix. And transmitting the precoding matrix indication to the base station.
  • FIG. 6 is a schematic block diagram of a terminal device according to an embodiment of the present invention. As shown in FIG. 6, the terminal device 600 includes:
  • the matrix of row R columns, N t is the number of antenna ports, R is the value of the rank corresponding to the rank indication, N t is greater than or equal to R, W 1 is a matrix of 2 M rows of N t rows, and W 2 is 2M rows 2K columns Matrix, W 3 is a matrix of 2K rows and R columns, where K is less than M, N t , R, M and K are positive integers, M is greater than or equal to 2, and N t is even, W 1 , W 2 and W 3 not a unit matrix, and W 2M column 1 in each column comprises 2 W 1 ⁇ W;
  • the precoding matrix W corresponds to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, and the first precoding matrix indication corresponds to the first precoding matrix W 1 ,
  • the second precoding matrix indication corresponds to the second precoding matrix W 2 , and the third precoding matrix indication corresponds to the third precoding matrix W 3 .
  • the sending unit 602 is configured to send the rank indication, the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication.
  • the terminal device further includes: a receiving unit 603, configured to receive configuration parameters sent by the base station.
  • the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication, the precoding matrix W refer to the method embodiment of the present invention. description of.
  • the processing unit of the terminal device reference may be made to the specific implementation of the terminal device in the foregoing method embodiment.
  • the terminal device that transmits the precoding matrix indication in the embodiment of the present invention satisfies system performance. In the case of demand, the number of bits indicated by the feedback precoding matrix is reduced.
  • FIG. 7 shows a schematic block diagram of a base station according to an embodiment of the present invention.
  • the base station 700 includes:
  • the receiving unit 701 is configured to receive a rank indication sent by the terminal device, the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication.
  • the processing unit 702 is configured to: in the precoding matrix set corresponding to the rank indication, according to the first precoding matrix indication, the second precoding matrix indication and the third precoding matrix indication, determine precoding Matrix W,
  • the first precoding matrix indication corresponds to the first precoding matrix W 1
  • the second precoding matrix indication corresponds to the second precoding matrix W 2
  • the third precoding matrix indication corresponds to The third precoding matrix W 3 .
  • the base station further includes: a sending unit 703, configured to send configuration parameters.
  • the first precoding matrix indication, the second precoding matrix indication, and the third precoding matrix indication, the precoding matrix W refer to the method embodiment of the present invention. description of.
  • the processing unit of the base station reference may be made to the specific implementation of the base station in the foregoing method embodiment.
  • the base station receiving the precoding matrix indication in the embodiment of the present invention reduces the number of bits indicated by the received precoding matrix when the system performance requirement is met.
  • the processing unit may be a processor, the receiving unit may be a receiver, and the sending unit may be a transmitter.
  • the terminal device including the processor 801, the transmitter 802, and the receiver 803 is as shown in FIG.
  • a base station including a processor 902, a transmitter 903, and a receiver 901 is shown in FIG.
  • the processor 801, 902 may be a central processing unit ("CPU"), and the processor 801, 902 may also be other general-purpose processors, digital signal processing. (DSP), application specific integrated circuit (ASIC), off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc.
  • the general purpose processor may be a microprocessor or the processor or any conventional processor or the like.

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Abstract

一种预编码矩阵指示的反馈和接收方法、终端设备，所述反馈方法包括：确定秩指示(101)，在与秩指示对应的预编码矩阵集合中确定预编码矩阵(102)，确定用于指示预编码矩阵的第一预编码矩阵指示、第二预编码矩阵指示和第三预编码矩阵指示(103)，UE向基站发送秩和所述第一预编码矩阵指示、第二预编码矩阵指示、第三预编码矩阵指示(104)。通过第一级和第二级反馈，待选向量个数大为减少，从而减小了计算第三级反馈的复杂度，同时减少了第三级反馈的比特个数。在满足系统性能需求的情况下，减小了反馈的预编码矩阵指示的比特数，实现了系统性能和终端设备反馈开销之间的平衡。

Description

一种预编码矩阵指示的反馈方法及装置 技术领域
本申请涉及移动通信领域，尤其涉及无线通信系统中的多天线技术。
背景技术
长期演进(long term evolution，LTE)系统广泛采用了多输入多输出(multiple input and Multiple Output，MIMO)技术。发送端可以采用预编码(precoding)技术对数据进行处理，从而提高信号传输质量或者速率。该发送端可以是基站，也可以是终端设备。
在LTE系统中，基站一般采用终端设备反馈预编码矩阵指示(precoding matrix indicator，PMI)的方式来获得预编码矩阵。通常称所使用的预编码矩阵的集合为码本或码本集合。码本或码本集合中的每个预编码矩阵也可以称为码字。
终端设备对信道状态信息(channel state information,CSI)进行量化并反馈给基站，基站根据该CSI确定预编码矩阵。现有LTE系统反馈的CSI信息包括秩指示(rank indication，RI)和PMI等，其中RI用于指示数据空间复用的数目。PMI用于指示预编码矩阵。
LTE标准中支持8个天线端口和16个天线端口。目前定义了两级码本反馈机制来达到减小终端用户反馈PMI的比特数，从而达到减小负载的目的。第一级反馈指示一个向量组，包含4个向量，可用于后续的处理，第二级反馈选取4个向量中的一个，被选取的向量可以用于数据预编码。其中，第一级反馈具有长周期/宽带特性，第二级反馈具有短周期/子带特性。
图1给出了二维天线阵列示意图。在图1中，天线端口分为45°极化和-45°极化。对一个极化方向，水平方向有N1个天线端口，垂直方向有N2个天线端口。
随着天线端口个数的增加，基站预编码后波束宽度也越来越窄。为了更好的覆盖整个系统带宽，第一级反馈中的向量组需要包括更多的向量。比如32个的天线端口，每个极化方向内会包含16个天线端口。如果要使得32天线端口的系统中的第一级反馈的向量组和16天线端口的系统中的第一级反馈的向量组有相同的覆盖空域，那么32天线端口的系统中的第一级反馈的向量组需 要包含16个列向量。如图2a，图2b所示。
如果在32天线端口的情况下，还是沿用当前的码本反馈机制，即第一级反馈的向量组包含4个向量，那么势必会影响覆盖带宽，造成码本的性能下降。
如果将第一级反馈的向量个数增加到16个，那么第二级反馈需要在这16个向量中选择，这会增加第二级反馈的比特个数，从而增加了终端设备的系统开销。
发明内容
本申请描述了预编码矩阵指示的反馈方法及装置，以在尽量满足系统性能需求的情况下，尽量减少终端设备的系统开销。
第一方面，一种确定预编码矩阵的方法，该方法包括：
终端设备确定秩指示,在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵W，所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列。
所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
所述终端设备发送所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示。
W1中的列的集合包括W1×W2中的每一列，表示的是从W1中的列中选出2K个列向量作为W1×W2的结果。使得后续待选向量集合中向量个数减少，从而减小了后续处理的计算复杂度，同时可以降低候选进行向量选择的反馈PMI的比特数。
第二方面，一种预编码矩阵指示的反馈方法，所述方法包括：：
基站接收终端设备发送的秩指示，第一预编码矩阵指示，第二预编码矩阵 指示和第三预编码矩阵指示；
所述基站在所述秩指示对应的预编码矩阵集合中，根据所述第一预编码矩阵指示，所述第二预编码矩阵指示和所述第三预编码矩阵指示，确定预编码矩阵W，
所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
第三方面，本发明实施例提供了一种终端设备，该终端设备具有实现上述方法设计中终端设备行为的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。所述模块可以是软件和/或硬件。
所述终端设备包括：
处理单元，用于确定秩指示，在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵W，所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3；
发送单元，用于发送所述秩指示、所述第一预编码矩阵指示、所述第二预 编码矩阵指示和所述第三预编码矩阵指示。
可选的，所述终端设备进一步包括：接收单元，用于接收基站发送的配置参数。
第四方面，本发明实施例提供了一种基站，该基站具有实现上述方法实际中基站行为的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
所述基站包括：
接收单元，用于接收终端设备发送的秩指示，第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示；
处理单元，用于在所述秩指示对应的预编码矩阵集合中，根据所述第一预编码矩阵指示，所述第二预编码矩阵指示和所述第三预编码矩阵指示，确定预编码矩阵W，
所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
可选的，所述基站进一步包括：发送单元，用于发送配置参数。
在第一方面到第四方面，还有如下可选设计。
可选的，所述秩指示对应的预编码矩阵集合中的每一个预编码矩阵W满足W＝W1×W2×W3。
可选的，W2满足
Figure PCTCN2016078298-appb-000001
其中X2为M行K列矩阵，X2的任意一列表示为ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
可选的，W1满足
Figure PCTCN2016078298-appb-000002
其中X1为Nt/2行M列的矩阵，
Figure PCTCN2016078298-appb-000003
vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
W3的任意一列，用
Figure PCTCN2016078298-appb-000004
表示，其中φn为复数，el为是K×1的列向量，其第l个元素为1，其余的元素为0，l为1到K的整数。
可选的，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B。
所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个，所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
第一子带对应的向量组中列向量的个数要小于系统带宽对应的向量组中向量的个数，从而减小了第二子带上向量选择所需要搜索的向量个数，并且可以减小在第二子带反馈所选向量指示所需的比特个数。
可选的，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
可选的，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。
可选的，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2，所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
可选的，所述发送周期P1，P2，P3由基站通过通过无线资源控制(Radio Resource Control,RRC)信令发送给终端设备。
不同预编码矩阵指示配置不同的发送周期，利用它们对应了信道的不同特性。有的对应信道随时间变换较快的部分，有的对应信道随时间变换较慢的部分。例如，第一预编码矩阵指示对应信道随时间变换最慢的部分，第二预编码矩阵指示对应信道随时间变换较慢的部分，第三预编码矩阵指示对应信道随时间变换较快的部分。根据信道特性，配置P1、P2、P3，可以节省反馈PMI的比特数。
可选的，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且T小于K，
所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。这么做，减少了反馈第二预编码矩阵指示需要的比特数。
可选的，所述W2中的2K个列向量由基站下发的配置参数和所述第二预编码矩阵指示指示。这么做，减少了反馈第二预编码矩阵指示需要的比特数。
可选的，所述配置参数用于指示所述W1的可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
可选的，所述配置参数为所述基站通过RRC信令发送给终端设备的配置参数。
可选的，所述W1中的X1满足
Figure PCTCN2016078298-appb-000005
其中
Figure PCTCN2016078298-appb-000006
是包含N1个元素的列向量。
Figure PCTCN2016078298-appb-000007
是包含N2个元素的列向量，N1×N2＝Nt/2,M1×M2＝M，
Figure PCTCN2016078298-appb-000008
表示克罗内克积。
可选的，所述W2中X2满足
Figure PCTCN2016078298-appb-000009
X3为M1行K1列的矩阵，X4为M2行K2列的矩阵，
Figure PCTCN2016078298-appb-000010
表示克罗内克积。
X3的任意一列表示为ei，ei是M1×1的列向量，其第i个元素为1，其余的元素为0，i的取值为1到M1的整数。
X4的任意一列表示为ej，ej是M2×1的列向量，其第j个元素为1，其余的元素为0，j的取值为1到M2的整数。
且K1×K2＝K，M1×M2＝M。
在第三方面和第四方面，发送单元可以是发送器，接收单元可以是接收器，处理单元可以是处理器。
本发明实施例还提供了一种系统，该系统包括上述实施例中的终端设备和基站。
在本申请中，第一预编码矩阵指示的反馈(或发送)可以认为是第一级反馈，第二预编码矩阵指示的反馈可以认为是第二级反馈，第三预编码矩阵指示的反馈可以认为是第三级反馈。
相较于现有技术，本申请提供的方案中预编码矩阵指示的反馈分为三级。 第二级反馈用于指示第一级反馈所指示的向量组中部分向量。由于待选择向量个数的减小，从而减小了所述终端计算第三级反馈的系统开销，并且减小了第三级反馈所需的比特数目，实现系统性能和终端设备反馈开销之间的更好的平衡。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍。显而易见地，下面附图中反映的仅仅是本发明的一部分实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得本发明的其他实施方式。而所有这些实施例或实施方式都在本发明的保护范围之内。
图1为二维天线阵列示意图；
图2a为8天线端口波束组覆盖空间的示意图；
图2b为32天线端口波束组覆盖空间的示意图；
图3为根据本发明实施例的反馈预编码矩阵指示的方法的示意性流程图；
图4为多径与向量组对应关系的示意图；
图5为第一子带和第二子带示意图；
图6为根据本发明实施例的终端设备的示意性框图；
图7为根据本发明实施例的基站的示意性框图；
图8为根据本发明另一实施例的终端设备的另一示意性框图；
图9为根据本发明另一实施例的基站的另一示意性框图。
具体实施方式
下面将结合附图，对本发明实施例中的技术方案进行清楚地描述。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明实施例描述的网络架构以及业务场景是为了更加清楚的说明本发 明实施例的技术方案，并不构成对于本发明实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本发明实施例提供的技术方案对于类似的技术问题，同样适用。
应理解，本发明实施例的技术方案可以应用于各种通信系统，例如：长期演进(long term evolution，LTE)系统、LTE频分双工(frequency division duplex，FDD)系统、LTE时分双工(Time Division Duplex，简称为“TDD”)通信系统等。还可以用于设备到设备(device to device,D2D)通信等通信中。
还应理解，在本发明实施例中，终端设备(terminal equipment)可称之为终端(terminal)，也可以是用户设备(user equipment，UE)、移动台(mobile station，MS)或移动终端(mobile terminal)等，该终端设备可以经无线接入网(Radio Access Network，RAN)与一个或多个核心网进行通信，例如，终端设备可以是移动电话(或称为“蜂窝”电话)或具有移动终端的计算机等，例如，终端设备还可以是便携式、袖珍式、手持式、计算机内置的或者车载的移动装置，它们与无线接入网交换语音和/或数据。
在本发明实施例中，基站可以是LTE中的演进型基站(evolutional node B，简称为“eNB或e-NodeB”)，也可以是其他基站，也可以是中继(relay)之类的接入网设备。对于D2D通信，还可以是D2D通信中的设备，本发明并不限定，但为描述方便，下述实施例将以eNB为例进行说明。
图3示出了根据本发明实施例的一种确定预编码矩阵的方法的示意性流程图。如图3所示，该方法包括：
步骤101，终端设备确定秩指示。
在步骤101中，一个秩的值对应一个秩指示。该终端设备向基站发送秩指示来指示该终端设备期望进行空间复用的下行数据的数目。例如，秩的值取值范围为1-8，秩指示由3个比特表示。当秩指示为000时，表示秩为1；当秩指示为001，表示秩为2,依次类推。总之，秩取某个值，就有一个秩指示的值和该秩对应。
可选的，终端设备可以基于CSI等信息确定用于指示数据空间复用的数目，即秩。可选的，基站向终端设备发送小区特定参考信号(cell-specific reference signal，CRS)，或发送信道状态信息参考信号(channel state information  reference signal，CSI-RS)。终端设备根据CRS，或CSI-RS，得到下行的信道估计和下行的干扰估计，然后根据这两者确定下行传输时终端设备期望的下行数据传输空间复用的数目，即秩。应理解，终端设备可以采用本领域技术人员所熟知的方法来确定秩，为了简洁，在此不再赘述。
步骤102，在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵。
在步骤102中，终端设备可以基于CSI-RS等参考信号，在与所述秩指示对应的预编码集合中，确定终端设备期望基站eNB发送下行数据时使用的预编码矩阵。
步骤103，确定用于指示所述预编码矩阵的第一预编码矩阵指示、第二预编码矩阵指示和第三预编码矩阵指示。
对基站和终端设备而言，每个秩(或秩指示)下都有一个预编码矩阵集合。而且，在给定秩的情况下，每个预编码矩阵由第一预编码矩阵指示、第二预编码矩阵指示和第三预编码矩阵指示来指示。第一预编码矩阵指示、第二预编码矩阵指示、第三预编码矩阵指示和预编码矩阵W之间有一一对应的关系。例如，对秩1，第一预编码矩阵指示，第二预编码矩阵指示，第三预编码矩阵指示分别由两个比特表示，一共6个比特表示预编码矩阵指示。而秩1的预编码矩阵集合包括2^6＝64个预编码矩阵。每个预编码矩阵W对应三个预编码矩阵指示。比如第一预编码矩阵指示的取值为00，第二预编码矩阵指示的取值为00，第三预编码矩阵指示的取值为00。相当于，这6个比特的预编码矩阵指示为000000，对应一个预编码矩阵W。当6个比特的预编码矩阵指示为000001时，对应另外一个预编码矩阵W。依此类推，每个预编码矩阵W都和预编码矩阵指示有一一对应的关系，相当于知道了预编码矩阵指示的值，就确定出了相应的预编码矩阵。
步骤104，终端设备向基站发送所述秩指示和所述第一预编码矩阵指示、第二预编码矩阵指示、第三预编码矩阵指示。
例如，物理上行共享信道(physical uplink shared channel，PUSCH)或其它信道上，向基站发送秩指示和用于指示所述预编码矩阵的预编码矩阵指示(第一预编码矩阵指示、第二预编码矩阵指示、第三预编码矩阵指示)。基站可以配置终端设备在PUSCH上反馈预编码矩阵指示，或者在物理上行控制信道(physical uplink control channel，PUCCH)上反馈预编码矩阵指示。对于该 终端设备发送该秩指示和第一预编码矩阵指示、第二预编码矩阵指示和第三预编码矩阵指示，该秩指示可以在3个预编码矩阵指示发送之前发送；也可以和这个3个预编码指示的一部分一起发送；也可以和这三个预编码指示的全部一起发送。秩指示和预编码矩阵指示的发送没有先后的限制。
在基站侧，步骤105，基站接收终端设备发送的秩指示以及预编码矩阵指示。其中，对于基站接收秩指示和第一预编码矩阵指示、第二预编码矩阵指示、第三预编码矩阵指示。秩指示可以在3个预编码矩阵指示之前接收；也可以和这个3个预编码指示的一部分一起接收；也可以和这三个预编码指示的全部一起接收。秩指示和预编码矩阵指示的接收没有先后的限制。
在基站侧，步骤106，在与所述秩指示对应的码本集合中，根据所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示确定预编码矩阵。
在基站侧，步骤107中，基站根据所述的预编码矩阵发送数据。
可选的，在步骤107中，基站根据步骤106中确定的预编码矩阵向终端设备发送数据。基站可以在物理下行共享信道(physical downlink shared channel，PDSCH)上向终端设备发送数据。发送数据时基站使用的预编码矩阵可以是终端设备反馈的预编码矩阵指示对应的预编码矩阵。也可以是根据此预编码矩阵经过变换，比如考虑了多用户MIMO之间的发送端的迫零算法，得到的另一个预编码矩阵。
上述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
W1中的列的集合包括W1×W2中的每一列，表示的是从W1中的列中选出2K个列向量作为W1×W2的结果。使得后续待选向量集合中向量个数减少， 从而减小了后续处理的计算复杂度，同时可以降低候选进行向量选择的反馈PMI的比特数。比如，W2用于在W1中选择列向量，使得W3中可选向量集的个数减少了，减小了反馈W3需要的比特个数，也降低了计算复杂度。
在本发明的实施例中，可选的一种实施方式中，所述秩指示对应的预编码矩阵集合中的每一个预编码矩阵W满足W＝W1×W2×W3。
随着水平维度方向或者垂直维度方向天线端口个数的增加，所形成的波束也越来越细，甚至有可能一个波束只能覆盖多径信道中的一条径。为了捕获更多的信道径，终端设备选择并反馈多个向量组用于基站的预编码是一个很好的方式，其中向量组的大小可以包含4个向量，或者更小，如包含2个向量。下面以32天线端口，天线配置(N1，N2)＝(16,1)(如图4所示)为例来介绍本方法。其中，N1为第一维度方向一个极化方向(45°极化或-45°极化)天线端口的数目，N2为第二维度方向一个极化方向天线端口的数目，N1×N2＝Nt/2。第一维度方向可以是水平维度方向(或垂直维度方向)，第二维度方向可以是垂直维度方向(或水平维度方向)。
在该天线形态下，W1中包含16个向量才能覆盖整个系统带宽。例如，
Figure PCTCN2016078298-appb-000011
由于W1是个分块对角矩阵，而且W1中，两个对角矩阵是一样的。
W1中包含的向量数目，指的是X1包含的列向量数目，不是指W1中列向量的数目。W1中列向量的数目是X1包含的列向量数目的2倍。通常X1中的列向量，当作用到一个极化方向的天线端口上，可以起到波束赋型的作用。比如，X1中的每一列都是DFT向量(DFT，Discrete Fourier Transform，离散傅里叶变换，)。所以，X1中的每个列向量可以认为是一个方向向量或波束向量。
DFT向量指Tⅹ1的预编码矩阵，该DFT向量v通常具有如下等式所示的形式：
Figure PCTCN2016078298-appb-000012
其中，N、m为整数(N不等于0)，通常N＝2x，x为非负整数，即N为2的x幂次方，并且该DFT向量v的第t个元素为ej2π(t - 1)m/N(t＝1，2，…，T)。 上标T表示矩阵转置。W1中的一个对角块X1用于一个极化方向，另一个对角块X1用于另一个极化方向。以图4为例，天线端口在水平方向排列，一个极化方向有16个天线端口。则矩阵X1的行数为16。W1中包含16个向量，相当于X1有16列。例如，X1每一列都可以是一个DFT向量。将X1中每4个向量组成一个向量组，一共4个向量组。例如，X1的第1到第4列做为第一向量组；X1的第5到第8列做为第二向量组；X1的第9到第12列做为第三向量组；X1的第13到第16列做为第四向量组。
W1中的16个向量，包含了终端设备在一个较长的时间内期望基站预编码时使用的向量。但是实际上，在某个的时刻，并不是该向量组中每个向量都能用上。比如对于某终端设备，其到基站天线端口的路径有两个强径，对第一强径，当基站使用第一向量组中的向量进行预编码时，产生的波束能以主波瓣的方向对准第一强径；当基站使用第四向量组中的向量进行预编码时，产生的波束能以主波瓣的方向对准第二强径。如图4所示。
在这种情况下，终端设备需要发送W1的对应第一预编码矩阵指示(包含16个波束向量)，并且进一步反馈在W1中选择的一个或者多个向量组的第二预编码矩阵指示。比如在本例中，终端设备发送第一向量组和第四向量组的指示给基站。
当终端设备测量获得信道的秩>2的时候，终端设备需要为每个上报的向量组选择与其正交的一个或者多个向量组，并将选择的正交的一个或者多个向量组的编号发送给基站。例如，终端设备确定的秩＝4，其向量组编号为1和4，向量组编号为1的向量组中包含的向量为[v1 v2 v3 v4]，向量组编号为2的向量组中包含的向量为[v5 v6 v7 v8]。同时所述终端还要将与向量组1正交的向量组1+k和与向量组4正交的向量组4+k’发送给基站,其中编号为1+k的向量组的向量为
Figure PCTCN2016078298-appb-000013
编号为1+k’的向量组的向量为[v5+k′ v6+k' v7+k' v8+k']。根据上述描述，得到
Figure PCTCN2016078298-appb-000014
Y＝[v1 … v8 v1+k … v4+k v5+k′ … v8+k′]。
在本发明的实施例中，可选的一种实施方式中，W2满足
Figure PCTCN2016078298-appb-000015
其中X2为M行K列矩阵，X2的任意一列表示为ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
在本发明的实施例中，可选的一种实施方式中，W1满足
Figure PCTCN2016078298-appb-000016
其中X1为Nt/2行M列的矩阵，X1＝[v0 … vM-1]，vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
W3的任意一列，用
Figure PCTCN2016078298-appb-000017
表示，其中φn为复数，el为是K×1的列向量，其第l个元素为1，其余的元素为0，l为1到K的整数。
例如，W1可以表示为
Figure PCTCN2016078298-appb-000018
其中，
Figure PCTCN2016078298-appb-000019
表示第一方向的第m个预编码向量，
Figure PCTCN2016078298-appb-000020
L1表示W1的X1中第一方向中列向量的个数。
Figure PCTCN2016078298-appb-000021
表示第二方向的第n个预编码向量，n＝0,1,…,L2-1。L2中表示W1的X1中第二方向中列向量的个数。Q1和Q2为生成上述列向量的生成参数，都为正整数。其中，第一方向可以是水平方向(或垂直方向)，第二方向可以是垂直方向(或水平方向)。
W2用于在W1的向量组中进一步选出K个列向量，可以表示为
Figure PCTCN2016078298-appb-000022
X2＝[ei … ej]M×K，X2为M行K列的矩阵。ei表示M×1的列向量，其中第i个元素为1，其余的元素为0；M＝L1×L2。
W3中的el作用是指示预编码的向量，φn作用是在两组极化天线之间进行 相位加权。因为预编码矩阵W的前Nt/2行对应一个极化方向的天线端口的预编码加权，后Nt/2行对应另一个极化方向的天线端口的预编码加权。
在本发明的实施例中，可选的一种实施方式中，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，
其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B；
所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个，所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
其中，下行系统带宽可以为一个载波的下行系统带宽，比如，如果下行只有一个载波，下行系统带宽就是这个载波的下行系统带宽。在载波聚合场景，如果下行有多个载波，则下行系统带宽就是终端设备反馈CSI对应的载波的下行系统带宽。比如，下行有两个载波，分别为载波1和载波2。终端设备当前反馈载波1的CSI，则下行系统带宽就是载波1的下行系统带宽。
可选的，终端设备为每个所述第一子带上报一个第二预编码矩阵指示，为每个所述第二子带上报一个第三预编码矩阵指示。
在本发明的实施例中，可选的一种实施方式中，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
例如，整个系统带宽分成A个第一子带，每个第一子带包含S个第二子带。终端设备为整个系统带宽向基站发送一个第二预编码矩阵指示。终端设备为系统带宽发送一个第一预编码指示；终端设备每个第一子带发送一个第二预编码矩阵指示，终端设备为每个第二子带发送一个第三预编码矩阵指示。
终端设备需要为每个第一子带选择第二预编码矩阵指示，其中第二预编码矩阵指示用于为所述子带在所述第一预编码矩阵中选择2K个列向量。在图5中，每个第一子带有4个第二子带。
由于对一个秩(或秩指示)而言，对应的预编码矩阵集合中的每一个预编码矩阵W可以表示为W＝W1×W2×W3。假设，W1包含有16个波束向量，则
Figure PCTCN2016078298-appb-000023
且X1中有16列，与16个波束向量对应。下面给出了不同天 线端口配置，不同的W1，W2的示例。
例如，在天线端口配置为(N1,N2)＝(8,2)的情况下，其中N1为水平方向的天线端口数目，N2为垂直方向的天线端口数目。W1的对角矩阵是8个水平方向和2个垂直方向向量的克罗内克积,一共16个波束向量。当天线端口配置为(N1,N2)＝(4,4)的情况下，W1中的波束向量是4个水平方向和4个垂直方向向量的克罗内克积，也是16个波束向量。将W1中的向量分成若干个向量组，每个向量组中包含4个或者8个波束向量。
以(N1,N2)＝(8,2)为例，W1中包含有16个波束向量，16个波束向量编号记为1,2，…16。以8个波束作为一个波束向量组，其中每两个相邻的波束向量组之间有4个波束向量是相互重叠的，因此16个波束向量可以分成3个波束向量组。则第一个波束向量组包含编号为1到8的波束向量,第二个波束向量组包含编号为5到12的波束向量；第三个波束向量组包含编号为9到16的波束向量。终端设备通过第二预编码矩阵指示指示出选择的哪个波束向量组。也就相当于确定了W2。这样，对于第三预编码指示，可以用3个比特选择使用哪个波束向量用于预编码。
也可以是，W1中包含有16个波束向量，分为4组，每组4个波束向量，第一波束向量组包含编号为1到4的波束向量,第二波束向量组包含编号为5到8的波束向量；第三波束向量组包含编号为9到12的波束向量，第四波束向量组包含编号为13到16的波束向量。相邻的组之间没有重叠的波束向量，终端设备通过第二预编码矩阵指示指示出选择的哪个波束向量组。
在本发明的实施例中，可选的一种实施方式中，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。本实施方式对应了预编码矩阵指示的宽带反馈。预编码矩阵指示的宽带反馈，指的反馈的预编码矩阵指示对应的频域资源是整个系统带宽。
在本发明的实施例中，可选的一种实施方式中，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2，所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
在本发明的实施例中，可选的一种实施方式中，所述发送周期P1，P2，P3 由基站通过无线资源控制(Radio Resource Control,RRC)信令发送给终端设备
不同预编码矩阵指示配置不同的发送周期，利用它们对应了信道的不同特性。有的对应信道随时间变换较快的部分，有的对应信道随时间变换较慢的部分。例如，第一预编码矩阵指示对应信道随时间变换最慢的部分，第二预编码矩阵指示对应信道随时间变换较慢的部分，第三预编码矩阵指示对应信道随时间变换较快的部分。根据信道特性，配置P1、P2、P3，可以节省反馈PMI的比特数。
例如，在LTE系统中，一个子帧(subframe)的长度是1毫秒，也是一个传输时间间隔(transmission time interval，TTI)的长度。TTI是指在无线链路中的一个独立解码传输的长度。
终端设备在PUCCH上反馈预编码矩阵指示。在第一反馈模式中，信道质量指示(channel quality indication，CQI)和第三预编码矩阵指示在一个子帧内通过PUCCH上报。秩指示和第一预编码矩阵指示在一个子帧内通过PUCCH上报。
秩指示和第一预编码矩阵指示的上报周期为P1；第二预编码矩阵指示的上报周期为P2；信道质量指示和第三预编码矩阵指示的上报周期为P3。其中P1＝T1P2,P2＝T2P3。比如T1＝10，T2＝4。
在PUCCH第二反馈模式中，RI与预编码类型指示(precoding type indication，PTI)第一预编码矩阵指示一起上报，同样有三个上报周期，P1，P2，P3。
在周期P1上报时刻，终端设备在PUCCH上上报RI，PTI和第一预编码矩阵指示。
在周期P2的上报时刻，当PTI＝0时，上报第二预编码矩阵指示；当PTI＝1时，上报宽带CQI和宽带W3。宽带CQI上报(CQI宽带反馈)，指的反馈的CQI对应的频域资源是整个系统带宽。
在周期P3的上报时刻，当PTI＝0时，上报宽带CQI和宽带W3；当PTI＝1时，上报子带CQI和子带W3对应的第三预编码矩阵指示。其中P1＝T1P2,P2＝T2P3。比如T1＝8，T2＝5。
在本发明的实施例中，可选的一种实施方式中，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且 T小于K，所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。
例如根据所述第一预编码矩阵指示，确定16个波束向量为[v1 … v16],其中[v1 v2 v3 v4]为必选的波束向量，不需要第二预编码矩阵指示，第二预编码矩阵指示只是用于指示另外一个向量组，比如用l来指示第二个向量组与第一个向量组的关系。例如W1×W2可以表示为
Figure PCTCN2016078298-appb-000024
其中，Y＝[v1 v2 v3 v4 v1+l … v4+l]，且Y为Nt/2行K列的矩阵。也可以直接指示第二个向量组，比如，第一预编码矩阵指示对应了4个向量组，其中第一个向量组是必选的向量，第二个预编码矩阵指示另外选择的一个的向量组。和需要通过第二个预编码矩阵指示来选择W1的多组向量比，第二个预编码矩阵指示减少了需要指示的向量组，进一步减少了反馈的比特数。比如，第二个预编码矩阵从指示两个向量组到指示一个向量组，减少了指示一个向量组需要的比特数。
在本发明的实施例中，可选的一种实施方式中，所述W2中的2K个列向量由基站下发的配置参数和所述第二预编码矩阵指示指示。
例如，W1中包含有16个波束向量，分为4组，每组4个向量，第一向量组包含编号为1到4的波束向量,第二向量组包含编号为5到8的波束向量；第三向量组包含编号为9到12的波束向量，第四向量组包含编号为13到16的波束向量。如本例中终端设备通过第二预编码矩阵指示将第一向量组和第四向量组的指示发送给基站，共8个列向量。为了进一步降低终端设备发送的预编码指示的比特数，可以根据配置参数进一步对所选向量组进行下采样，例如当配置参数为1的时候，8个向量中选择第一个到第四个向量；当配置参数为2的时候，8个向量中选择的第一个、第二个、第五个和第六个列向量；当 配置参数为3的时候，8个向量中选择第一个、第三个第六个和第八个列向量；当配置参数为4的时候，8个向量中选择第一个、第四个、第五个和第八个列向量。例如终端设备通过第二预编码矩阵指示指示出8个向量，记为v1,v2,…v8,如果没有配置参数对所选向量组进行下采样，则
Figure PCTCN2016078298-appb-000025
Y＝[v1 v2 ... v8]，包含8个向量，更进一步说W1×W2包含8个波束向量；如果有配置参数对所选向量组进行下采样，且配置参数为1，则
Figure PCTCN2016078298-appb-000026
Y＝[v1 v2 v3 v4]，包含4个向量，更进一步说W1×W2包含4个波束向量。由于配置参数是基站配置的，配置后就固定，不占终端设备的反馈比特。这样，对于第三预编码指示，可以只用2个比特选择使用哪个波束向量用于预编码。如果没有配置参数，需要用3个比特选择使用哪个波束向量用于预编码。所以，对本实施方式，可以减少第三预编码指示反馈的比特数。
可选的，配置参数可以是基站通过RRC信令发送给终端设备。
在本发明的实施例中，可选的一种实施方式中，所述配置参数用于指示所述W1的可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
比如，第一预编码指示出W1中包含有16个波束向量。以4个波束作为一个波束向量组，可以分成4个波束组。通过配置参数，确定了其中两个波束向量组。比如，通过配置参数，确定第一个和第三个波束向量组。由于每个向量组有4个波束向量，则配置参数一共选择了8个波束向量。相当于本实施方式中J＝8×2＝16。第二预编码指示进一步选出第一波束向量组还是第三个波束向量组用作后续处理。通过配置参数，减少了反馈第二预编码指示的比特数。
在本发明的实施例中，可选的一种实施方式中，所述W1中的X1满足
Figure PCTCN2016078298-appb-000027
其中
Figure PCTCN2016078298-appb-000028
是包含N1个元素的列向量。
Figure PCTCN2016078298-appb-000029
是包含N2个元素的列向量，N1×N2＝Nt/2,M1×M2＝M，
Figure PCTCN2016078298-appb-000030
表示克罗内克积。
在本发明的实施例中，可选的一种实施方式中，所述W2中X2满足
Figure PCTCN2016078298-appb-000031
X3为M1行K1列的矩阵，X4为M2行K2列的矩阵，
Figure PCTCN2016078298-appb-000032
表示克罗内克积。
X3的任意一列表示为ei，ei是M1×1的列向量，其第i个元素为1，其余的元素为0，i的取值为1到M1的整数。
X4的任意一列表示为ej，ej是M2×1的列向量，其第j个元素为1，其余的元素为0，j的取值为1到M2的整数。
且K1×K2＝K，M1×M2＝M。
在上述实施例中，步骤102,103,可以没有先后的顺序，可以同时确定。因为当确定了终端设备期望基站使用的预编码矩阵时，也就确定了对应的预编码矩阵指示。
步骤101和步骤102,103,步骤101可以在步骤102,103之前；也可以步骤101，102,103同时执行。
比如，所述UE的接收信号模型为
y＝HWs+n    (2)
其中y是接收信号矢量，H是信道矩阵,W是预编码矩阵，s是发射的符号矢量，n是干扰加噪声。
终端设备遍历所有秩以及每个秩所对应的所有编码矩阵，并计算每个预编码矩阵进行预编码后得到的信道容量。每个预编码矩阵，得到一个信道容量。信道容量可以是发送端能够正确发送的比特数目。得到最大的信道容量对应的预编码矩阵，和与这个预编码矩阵对应的秩。终端设备把这个预编码矩阵对应的秩指示，这个预编码矩阵对应的预编码矩阵指示发送给基站。
当秩确定的情况下，比如，在某个子帧，终端设备需要发送预编码矩阵指示。在之前，已经发送了秩指示。则终端设备只需要遍历秩指示对应的预编码矩阵集合。比如秩指示对应的秩为1，则终端设备只需要遍历秩＝1的预编码矩阵集合，得到使得信道容量最大的预编码矩阵。并将对应的预编码矩阵指示发送给基站。
终端设备遍历一个秩对应的预编码矩阵时，可以通过预编码矩阵指示来获得预编码矩阵。例如，遍历预编码矩阵指示，在遍历到某个预编码矩阵指示时，根据这个预编码矩阵指示得到预编码矩阵，并根据此预编码矩阵计算信道容量。也可以直接遍历预编码矩阵，当选择了使得信道容量最大的预编码矩阵后，根据预编码矩阵和预编码矩阵指示的一一对应关系，得到预编码矩阵指示。并将此预编码矩阵指示发送给基站。
上文中结合图3，详细描述了根据本发明实施例的方法，下面将结合图6至图9，详细描述根据本发明实施例的终端设备和基站。
图6示出了根据本发明实施例的终端设备的示意性框图，如图6所示，该终端设备600包括：
处理单元601，用于确定秩指示，在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵W，所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
发送单元602，用于发送所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示。
可选的，所述终端设备进一步包括：接收单元603，用于接收基站发送的配置参数。
对所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示、所述预编码矩阵W的进一步描述，可以参见本发明方法实施例的描述。对于终端设备的处理单元而言，具体实现可以参照上述方法实施例中的终端设备的具体实现。
因此，本发明实施例的发送预编码矩阵指示的终端设备，在满足系统性能 需求的情况下，减小了反馈的预编码矩阵指示的比特数。
图7示出了根据本发明实施例的基站的示意性框图。如图7所示，该基站700包括：
接收单元701，用于接收终端设备发送的秩指示，第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示。
处理单元702，用于在所述秩指示对应的预编码矩阵集合中，根据所述第一预编码矩阵指示，所述第二预编码矩阵指示和所述第三预编码矩阵指示，确定预编码矩阵W，
所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
可选的，所述基站进一步包括：发送单元703，用于发送配置参数。
对所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示、所述预编码矩阵W的进一步描述，可以参见本发明方法实施例的描述。对于基站的处理单元而言，具体实现可以参照上述方法实施例中的基站的具体实现。
因此，本发明实施例的接收预编码矩阵指示的基站，在满足系统性能需求的情况下，减小了收到的预编码矩阵指示的比特数。
上述处理单元具体可以是处理器，接收单元可以是接收器，发送单元可以是发送器。包括处理器801、发送器802和接收器803的终端设备如图8所示。包括处理器902、发送器903和接收器901的基站如图9所示。
应理解，在本发明实施例中，该处理器801、902可以是中央处理单元(Central Processing Unit，简称为“CPU”)，该处理器801、902还可以是其他通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现成可编程门阵列(FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
以上所述的具体实施方式，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施方式而已，并不用于限定本发明的保护范围，凡在本发明的技术方案的基础之上，所做的任何修改、等同替换、改进等，均应包括在本发明的保护范围之内。

Claims (40)

  1. 一种预编码矩阵指示的反馈方法，所述方法包括：
    终端设备确定秩指示,在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵W，所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
    所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3；
    所述终端设备发送所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示。
  2. 根据权利要求1所述的方法，其特征在于，
    W2满足
    Figure PCTCN2016078298-appb-100001
    其中X2为M行K列矩阵，X2的任意一列表示为ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
  3. 根据权利要求1或2所述的方法，其特征在于，
    W1满足
    Figure PCTCN2016078298-appb-100002
    其中X1为Nt/2行M列的矩阵，X1＝[v0 … vM-1]，vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
    W3的任意一列，用
    Figure PCTCN2016078298-appb-100003
    表示，其中φn为复数，el为是K×1的列向量，其第l个元素为1，其余的元素为0，l为1到K的整数。
  4. 根据权利要求1、2或3所述的方法，其特征在于，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，
    其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B；
    所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个， 所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
  5. 根据权利要求4所述的方法，其特征在于，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
  6. 根据权利要求1、2或3所述的方法，其特征在于，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。
  7. 根据权利要求1至6任意一项所述的方法，其特征在于，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2，所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
  8. 根据权利要求1至7任意一项所述的方法，其特征在于，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且T小于K，
    所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。
  9. 根据权利要求1至7任意一项所述的方法，其特征在于，所述W2中的2K个列向量由基站下发的配置参数和所述第二预编码矩阵指示指示。
  10. 根据权利要求9所述的方法，其特征在于，所述配置参数用于指示所述W1的可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
  11. 一种预编码矩阵指示的接收方法，所述方法包括：
    基站接收终端设备发送的秩指示，第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示；
    所述基站在所述秩指示对应的预编码矩阵集合中，根据所述第一预编码矩阵指示，所述第二预编码矩阵指示和所述第三预编码矩阵指示，确定预编码矩阵W，
    所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M 列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
    所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
  12. 根据权利要求11所述的方法，其特征在于，
    W2满足
    Figure PCTCN2016078298-appb-100004
    其中X2为M行K列矩阵，X2的任意一列表示为ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
  13. 根据权利要求11或12所述的方法，其特征在于，
    W1满足
    Figure PCTCN2016078298-appb-100005
    其中X1为Nt/2行M列的矩阵，X1＝[v0 … vM-1]，vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
    W3的任意一列，用
    Figure PCTCN2016078298-appb-100006
    表示，其中φn为复数，el为是K×1的列向量，其第l个元素为1，其余的元素为0，l为1到K的整数。
  14. 根据权利要求11、12或13所述的方法，其特征在于，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，
    其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B；
    所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个，所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
  15. 根据权利要求14所述的方法，其特征在于，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
  16. 根据权利要求11、12或13所述的方法，其特征在于，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。
  17. 根据权利要求11至16任意一项所述的方法，其特征在于，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2， 所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
  18. 根据权利要求11至17任意一项所述的方法，其特征在于，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且T小于K，
    所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。
  19. 根据权利要求11至17任意一项所述的方法，其特征在于，所述W2中的2K个列向量由基站下发的配置参数和所述第二预编码矩阵指示指示。
  20. 根据权利要求19所述的方法，其特征在于，所述配置参数用于指示所述W1中可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
  21. 一种终端设备,其特征在于，包括：
    处理单元，用于确定秩指示，在与所述秩指示对应的预编码矩阵集合中确定预编码矩阵W，所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
    所述预编码矩阵W对应于第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示，且所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3；
    发送单元，用于发送所述秩指示、所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示。
  22. 根据权利要求21所述的终端设备，其特征在于，
    W2满足
    Figure PCTCN2016078298-appb-100007
    其中X2为M行K列矩阵，X2的任意一列表示为 ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
  23. 根据权利要求21或22所述的终端设备，其特征在于，
    W1满足
    Figure PCTCN2016078298-appb-100008
    其中X1为Nt/2行M列的矩阵，X1＝[v0 … vM-1]，vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
    W3的任意一列，用
    Figure PCTCN2016078298-appb-100009
    表示，其中φn为复数，el为是K×1的列向量，其第l个元素为1，其余的元素为0，l为1到K的整数。
  24. 根据权利要求21、22或23所述的终端设备，其特征在于，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，
    其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B；
    所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个，所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
  25. 根据权利要求24所述的终端设备，其特征在于，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
  26. 根据权利要求21、22或23所述的终端设备，其特征在于，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。
  27. 根据权利要求21至26任意一项所述的终端设备，其特征在于，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2，所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
  28. 根据权利要求21至27任意一项所述的终端设备，其特征在于，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且T小于K，
    所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。
  29. 根据权利要求21至27任意一项所述的终端设备，其特征在于，所述 终端设备进一步包括：接收单元，用于接收基站发送的配置参数；
    所述W2中的2K个列向量由所述配置参数和所述第二预编码矩阵指示指示。
  30. 根据权利要求29所述的终端设备，其特征在于，所述配置参数用于指示所述W1的可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
  31. 一种基站，其特征在于，包括：
    接收单元，用于接收终端设备发送的秩指示，第一预编码矩阵指示，第二预编码矩阵指示和第三预编码矩阵指示；
    处理单元，用于在所述秩指示对应的预编码矩阵集合中，根据所述第一预编码矩阵指示，所述第二预编码矩阵指示和所述第三预编码矩阵指示，确定预编码矩阵W，
    所述W满足W＝W1×W2×W3,其中，W是Nt行R列的矩阵，Nt为天线端口数目，R为所述秩指示对应的秩的值，Nt大于或等于R，W1是Nt行2M列的矩阵，W2是2M行2K列的矩阵，W3是2K行R列的矩阵，其中K小于M,Nt，R，M和K都为正整数，M大于等于2，且Nt为偶数，W1，W2和W3都不为单位矩阵，且W1中的2M列包括W1×W2中的每一列；
    所述第一预编码矩阵指示对应于所述第一预编码矩阵W1，所述第二预编码矩阵指示对应于所述第二预编码矩阵W2，所述第三预编码矩阵指示对应于所述第三预编码矩阵W3。
  32. 根据权利要求31所述的基站，其特征在于，
    W2满足
    Figure PCTCN2016078298-appb-100010
    其中X2为M行K列矩阵，X2的任意一列表示为ep，ep是M×1的列向量，其第p个元素为1，其余的元素为0，p为1到M的整数。
  33. 根据权利要求31或32所述的基站，其特征在于，
    W1满足
    Figure PCTCN2016078298-appb-100011
    其中X1为Nt/2行M列的矩阵，X1＝[v0 … vM-1]，vo是包含Nt/2个元素的列向量，o为0到M-1的整数；
    W3的任意一列，用
    Figure PCTCN2016078298-appb-100012
    表示，其中φn为复数，el为是K×1的列向量，其 第l个元素为1，其余的元素为0，l为1到K的整数。
  34. 根据权利要求31、32或33所述的基站，其特征在于，所述第一预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽，
    其中，所述下行系统带宽包括A个第一子带，B个第二子带，A，B为大于1的正整数，且A小于等于B；
    所述第二预编码矩阵指示对应的频域资源为所述A个第一子带中的一个，所述第三预编码矩阵指示对应的频域资源为所述B个第二子带中的一个。
  35. 根据权利要求34所述的基站，其特征在于，所述A个第一子带中至少一个第一子带的频域资源与所述B个第二子带中的至少两个第二子带的频域资源相同。
  36. 根据权利要求31、32或33所述的基站，其特征在于，所述第一预编码矩阵指示、所述第二预编码矩阵指示和所述第三预编码矩阵指示所对应的频域资源为所述终端设备的下行系统带宽。
  37. 根据权利要求31至36任意一项所述的基站，其特征在于，所述第一预编码矩阵指示的发送周期为P1，所述第二预编码矩阵指示的发送周期为P2，所述第三预编码矩阵指示的发送周期为P3，其中，P1大于等于P2，P2大于等于P3。
  38. 根据权利要求31至37任意一项所述的基站，其特征在于，所述W2中2K个列向量中T个列向量由所述第一预编码矩阵指示指示，T大为大于等于2的整数，且T小于K，
    所述W2中除去所述T个列向量中的2K-T个列向量由所述T个列向量和所述第二预编码矩阵指示指示。
  39. 根据权利要求31至37任意一项所述的基站，其特征在于，所述基站进一步包括：发送单元，用于发送配置参数；
    所述W2中的2K个列向量由所述配置参数和所述第二预编码矩阵指示指示。
  40. 根据权利要求39所述的基站，其特征在于，所述配置参数用于指示所述W1中可选列向量集合，且该可选列向量集合中包含J个列向量，J满足2K<J<2M。
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