CN106936486B

CN106936486B - CSI feedback method and device

Info

Publication number: CN106936486B
Application number: CN201511021278.8A
Authority: CN
Inventors: 陈文洪; 陈润华; 高秋彬
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: China Academy of Telecommunications Technology CATT; Datang Mobile Communications Equipment Co Ltd
Priority date: 2015-12-30
Filing date: 2015-12-30
Publication date: 2020-07-21
Anticipated expiration: 2035-12-30
Also published as: CN106936486A; WO2017114513A1

Abstract

The invention discloses a CSI feedback method and a device. In the invention, the terminal expands the initial precoding matrix set according to the agreed column vector arrangement mode to obtain an expanded precoding matrix set, and performs CSI measurement and feedback according to the expanded precoding matrix set. Because the extended precoding matrix set is obtained on the basis of extending the initial precoding matrix set, and the scale of the extended precoding matrix is larger than that of the initial precoding matrix set, the CSI measurement and feedback are carried out on the basis of the extended precoding matrix set, compared with the CSI measurement and feedback carried out on the basis of the initial precoding matrix set, the CSI determined and fed back by the terminal can reflect the actual channel state better, and the possibility that the SINRs of a plurality of data streams mapped to the same code word are too large in difference is further reduced.

Description

CSI feedback method and device

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for CSI (Channel State Information) feedback.

Background

Mobile and broadband are the developing directions of modern communication technologies, and 3GPP (3rd Generation partnership project) has focused on L TE (L ong Term Evolution ) system as the Evolution of 3G system, with the goal of developing 3GPP radio access technology to evolve toward high data rate, low delay and optimized packet data application.

L TE Rel-8 system introduces closed-loop Precoding technique to improve spectrum efficiency, the closed-loop Precoding technique requires to keep the same Precoding Matrix set called codebook at base station and terminal, the size of codebook corresponding to different transmission Rank (Rank) and the code word contained may be different, the transmission Rank is assumed as the downlink transmission layer number.

At most, in an L TE system, transmission of two downlink codewords is supported, each codeword may have a respective modulation coding mode, and an independent HARQ (Hybrid Automatic Repeat reQuest) process is adopted, if the number of layers for downlink transmission is greater than 2, one codeword may be mapped to multiple data streams (one data stream is one layer), the mapping relationship between codewords and layers is predetermined, if the number of layers L is an even number, the number of layers mapped by each codeword is L/2, if the number of layers L is an odd number, the number of layers mapped by two codewords is (L-1)/2 and (L +1)/2, respectively, when downlink precoding is performed, precoding vectors adopted by each data stream are different, so that when a receiving end performs Channel Quality Indication (SINR) estimation on each data stream, a Signal to interference plus Noise Ratio (SINR) of each data stream is different, and when a CQI (Channel Quality Indication) estimation is performed on each data stream, an equivalent SINR of the same data stream is generally processed, so that all data streams are subjected to equivalent SINR calculation, such as an equivalent SINR, and all data stream is calculated.

If the SINR differences of multiple data streams mapped to the same codeword are large due to different precoding gains, the same modulation and coding scheme may cause that the modulation and coding scheme of some data streams is too high or too low and is not matched with the detected SINR of the data streams, so that the transmission throughput of the data streams is reduced, and the total data transmission rate is affected.

Disclosure of Invention

The embodiment of the invention provides a CSI feedback method and a device, which are used for carrying out CSI feedback based on an extended precoding matrix set and improving the matching degree of CSI fed back by a terminal and a channel state, so that the possibility of overlarge SINR difference of a plurality of data streams mapped to the same code word is reduced.

The CSI feedback method provided by the embodiment of the invention comprises the following steps:

the terminal expands the initial pre-coding matrix set according to an agreed column vector arrangement mode to obtain an expanded pre-coding matrix set;

the terminal carries out CSI measurement according to the extended precoding matrix set;

and the terminal feeds back the measured CSI to the base station.

Preferably, the terminal expands the initial precoding matrix set according to an agreed column vector arrangement mode, including:

expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix;

and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Preferably, the initial precoding matrix set includes N subsets, each subset corresponds to a value of a transmission rank, the number of column vectors of the initial precoding matrix in one subset is equal to the value of the transmission rank corresponding to the subset, and N is an integer greater than or equal to 1.

The column vector arrangement modes used when the initial precoding matrix corresponding to the same transmission rank value is expanded are the same.

Preferably, in all the extended precoding matrices corresponding to one initial precoding matrix, among column vectors of any two extended precoding matrices, a column vector mapped to one codeword in one extended precoding matrix is different from a column vector mapped to any codeword in another extended precoding matrix.

Preferably, if the number of column vectors of the initial precoding matrix is greater than a set threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.

Preferably, the CSI measurement performed by the terminal according to the extended precoding matrix set includes:

and the terminal takes the extended precoding matrix in the extended precoding matrix set as a precoding matrix used for downlink transmission, and measures one or more CSI (channel state information) in a Precoding Matrix Indicator (PMI), a Rank Indicator (RI) and a Channel Quality Indicator (CQI) according to the extended precoding matrix set, wherein the PMI is an index of the extended precoding matrix in the extended precoding matrix set.

Preferably, before the terminal expands the initial precoding matrix set according to the agreed column vector arrangement mode, the method further includes:

the terminal determines an effective precoding matrix in the initial precoding matrix set according to the effective precoding matrix indication information sent by the base station;

the terminal expands the initial precoding matrix set according to the agreed column vector arrangement mode, and the method comprises the following steps:

and the terminal expands the effective precoding matrix in the initial precoding matrix set according to an agreed column vector arrangement mode.

Another embodiment of the present invention provides a CSI feedback method, including:

the base station expands the initial pre-coding matrix set according to the agreed column vector arrangement mode to obtain an expanded pre-coding matrix set;

and the base station receives CSI measured and fed back by the terminal according to the extended precoding matrix set, wherein the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by extending the initial precoding matrix set by the terminal according to the agreed column vector arrangement mode.

Preferably, the base station expands the initial precoding matrix set according to an agreed column vector arrangement mode, including:

Preferably, the method further comprises the following steps: and the base station sends effective precoding matrix indication information to a terminal, wherein the effective precoding matrix indication information is used for indicating an effective precoding matrix in the initial precoding matrix set.

The terminal provided by the embodiment of the invention comprises:

the extension module is used for extending the initial precoding matrix set according to an agreed column vector arrangement mode to obtain an extended precoding matrix set;

a measurement module, configured to perform CSI measurement according to the extended precoding matrix set;

and the feedback module is used for feeding back the measured CSI to the base station.

Preferably, the extension module is specifically configured to: expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix; and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Preferably, the measurement module is specifically configured to: and taking an extended precoding matrix in the extended precoding matrix set as a precoding matrix used for downlink transmission, and measuring one or more CSI (channel state information) in a Precoding Matrix Indicator (PMI), a Rank Indicator (RI) and a Channel Quality Indicator (CQI) according to the extended precoding matrix set, wherein the PMI is an index of the extended precoding matrix in the extended precoding matrix set.

The base station provided by the embodiment of the invention comprises:

and the receiving module is used for receiving the CSI measured and fed back by the terminal according to the extended precoding matrix set, wherein the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by extending the initial precoding matrix set by the terminal according to the agreed column vector arrangement mode.

Another embodiment of the present invention provides a terminal, including:

a transceiver;

a memory for storing computer program instructions;

a processor, coupled to the memory, for reading computer program instructions stored by the memory and, in response, performing the following:

expanding the initial pre-coding matrix set according to an agreed column vector arrangement mode to obtain an expanded pre-coding matrix set;

performing CSI measurement according to the extended precoding matrix set;

and feeding back the measured CSI to the base station.

Another embodiment of the present invention provides a base station, including:

a transceiver;

a memory for storing computer program instructions;

and receiving the CSI measured and fed back by the terminal according to the extended precoding matrix set, wherein the extended precoding matrix on which the terminal performs CSI measurement and feedback is obtained by the terminal expanding the initial precoding matrix set according to the agreed column vector arrangement mode.

In the embodiment of the invention, the terminal expands the initial precoding matrix set according to the appointed column vector arrangement mode to obtain the expanded precoding matrix set, and performs CSI measurement and feedback according to the expanded precoding matrix set. Because the extended precoding matrix set is obtained on the basis of extending the initial precoding matrix set, and the scale of the extended precoding matrix is larger than that of the initial precoding matrix set, the CSI measurement and feedback are carried out on the basis of the extended precoding matrix set, compared with the CSI measurement and feedback carried out on the basis of the initial precoding matrix set, the CSI determined and fed back by the terminal can reflect the actual channel state better, and the possibility that the SINRs of a plurality of data streams mapped to the same code word are too large in difference is further reduced.

Drawings

Fig. 1 is a schematic structural diagram of a MIMO system using a single user as an example in the prior art;

fig. 2 is a schematic diagram of a transmission structure of a codebook-based precoding technique in the prior art;

fig. 3 is a schematic diagram of a CSI feedback process implemented on a terminal side according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a CSI feedback process implemented at a base station according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a terminal according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a base station according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a terminal according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a base station according to an embodiment of the present invention.

Detailed Description

L TE network adopts MIMO technology to increase system capacity and improve throughput, FIG. 1 shows a structure diagram of MIMO system, which takes single user as an example, the transmitting end, such as base station, and the receiving end, such as terminal, all have multiple antennas, at the transmitting end, the input serial code stream is converted into several parallel independent sub-code streams through a series of pre-processing (modulation, coding, weighting, mapping), and sent out through different transmitting antennas.

However, due to the correlation of channels in a Channel Matrix, the increase of capacity causes interference to be correspondingly increased, in order to reduce the complexity of a terminal in eliminating the influence between the channels and reduce system overhead and maximally improve the system capacity of MIMO, a Precoding technique is introduced in the prior art, several main transmission modes of a physical downlink shared Channel are realized by Precoding in the process of processing a physical layer of L TE, a closed-loop Precoding technique is introduced in a L TE Rel-8 system to improve spectral efficiency, closed-loop Precoding first requires that a set of the same Precoding Matrix is stored in both a base station and a terminal, which is called a codebook.

In downlink MIMO transmission based on a codebook, different columns of codewords in the codebook correspond to different data streams, but the current codebook design cannot guarantee that the received SINRs of multiple data streams mapped to the same transport block are close. If the received SINR difference between multiple data streams mapped to the same transport block is large after they are precoded with the best codeword, the actual code rate of each data stream will be higher or lower due to the same modulation and coding scheme adopted by these streams, which affects the data transmission performance and fails to achieve the expected spectral efficiency.

The embodiment of the invention provides a downlink CSI feedback method, a terminal can obtain an extended precoding matrix set according to different column vector arrangements of each precoding matrix in an initial precoding matrix set, and CSI measurement and feedback are carried out on the basis of the extended precoding matrix set, so that performance loss caused by too large SINR difference among a plurality of data streams mapped to the same code word is avoided.

In the embodiment of the present invention, the base station may be an L TE system or an evolved Node B (eNB or e-NodeB) in an evolved system thereof, a macro base station, a micro base station (also referred to as a "small base station"), a pico base station, an Access Point (AP) or a Transmission Point (TP).

In the embodiment of the present invention, a Terminal may also be referred to as User Equipment (UE), or may be referred to as Terminal, Mobile Station (MS), Mobile Terminal (RAN), and the like, and the Terminal may communicate with one or more core networks through a Radio Access Network (RAN), for example, the Terminal may be a Mobile phone (or may be referred to as a "cellular" phone), a computer with a Mobile Terminal, and the like, and for example, the Terminal may also be a portable, pocket, hand-held, computer-built-in, or vehicle-mounted Mobile device, and they exchange voice and/or data with the RAN.

For convenience of description, the following embodiments will be described taking a base station and a terminal as examples.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 2 shows a wireless network structure adopting a precoding technique based on a precoding matrix set, and the architecture is also applicable to the embodiment of the present invention. Specifically, the structure includes a base station 201 and a terminal 202, and a radio link 203. Terminal 202 and base station 201 each have multiple antennas. Terminal 202 and base station 201 are configured with the same set of precoding matrices (codebooks). After measuring the downlink channel and determining the precoding matrix, the terminal 202 feeds back the precoding matrix index PMI corresponding to the precoding matrix to the base station 201 through the wireless link 203. Wherein the fed back CSI may include: one or more of a CQI indicating the quality of a wireless communication channel between the base station and the terminal, a PMI indicating a preferred precoding matrix for shaping the transmission signal and an RI indicating the number of useful transmission layers of a data channel preferred by the terminal, and an estimate of channel coefficients. The fed back CSI enables the base station 201 to adaptively configure a suitable transmission scheme to improve coverage, or user data transmission rate, or more accurately predict channel quality for future transmissions to the terminal 202.

In the embodiment of the invention, the initial precoding matrix set can be predetermined at the base station side and the terminal side, and the base station can also configure the precoding matrix set to the terminal. For example, the base station may indicate configuration parameters of some precoding matrix sets, so that the terminal may obtain an initial precoding matrix according to the parameters.

If the subset constraint condition of the precoding matrix set is configured, the initial precoding matrix used by the base station and the terminal is obtained according to the agreed (or configured) initial precoding matrix set and the subset constraint condition of the precoding matrix set. Specifically, the terminal determines an effective precoding matrix in the initial precoding matrix set according to the effective precoding matrix indication information sent by the base station. When the terminal expands the initial precoding matrix set according to the agreed column vector arrangement mode, the terminal expands the effective precoding matrix in the initial precoding matrix set according to the agreed column vector arrangement mode to obtain an expanded precoding matrix set.

For example, the base station and the terminal agree in advance an initial precoding matrix set with a size of K, where K represents the number of initial precoding matrices in the set, and the base station indicates L initial precoding matrices in the initial precoding matrix set as effective precoding matrices in a bitmap manner, then the initial precoding matrix set on which the terminal performs precoding matrix set extension is a set consisting of L effective initial precoding matrices.

Referring to fig. 3, a schematic diagram of a CSI feedback process implemented by a terminal side according to an embodiment of the present application is shown, where the process may include the following steps:

step 301: and the terminal expands the initial pre-coding matrix set according to the appointed column vector arrangement mode to obtain an expanded pre-coding matrix set.

In this step, an extension rule used for extending the precoding matrix set may be predetermined, and the extension rule may specifically include one or more column vector arrangement modes. The terminal may arrange the column vectors of the initial precoding matrix in the initial precoding matrix set according to one or more agreed column vector arrangement modes to obtain an extended precoding matrix corresponding to the initial precoding matrix. According to the number of the agreed column vector arrangement modes, one or more extended precoding matrices can be obtained based on one initial precoding matrix, that is, one or more extended precoding matrices corresponding to one initial precoding matrix are obtained. For example, if there are N predetermined column vector permutation manners (N is an integer greater than 1), N extended precoding matrices may be obtained after sequencing the column vectors of an initial precoding matrix according to the column vector permutation manner.

Each initial precoding matrix in the initial precoding matrix set can be extended by using a plurality of column vector arrangement modes (except for the initial precoding matrix corresponding to rank 1). In specific implementation, for part of initial precoding matrices in the initial precoding matrix set, the initial precoding matrix set can be expanded according to an agreed column vector arrangement mode to obtain an expanded precoding matrix; for the rest of the initial precoding matrices in the initial precoding matrix set, the part of the initial precoding matrices can be used as corresponding extended precoding matrices.

For example, assuming that M is 3, the agreed arrangement of the three column vectors { V1V2V3} may include three (where the following numbers are indexes of the column vectors) {1,2,3} {2,1,3} {3,1,2}, after the terminal rearranges one N × M-dimensional matrix in the initial precoding matrix set according to the three column vector arrangement manners, three extended precoding matrices may be obtained, namely [ V1V2V3], [ V2V1V3], and [ V3V1V2 ].

For example, assuming that the size of the initial precoding matrix set is L (L represents the number of initial precoding matrices in the set, L is an integer greater than or equal to 1), and each of the initial precoding matrices in the initial precoding matrix set has P (P is an integer greater than or equal to 1) agreed column vector arrangement modes, the size of the obtained extended precoding matrix set is L× P.

According to the number of all possible values of rank, the initial precoding matrix set may include a corresponding number of subsets, each subset corresponds to a value of rank, and the number of column vectors of the initial precoding matrix in a subset is equal to the value of rank corresponding to the subset. Where rank denotes the number of possible transmission layers or the number of transmission data streams, for example, in the case that the system supports up to 8 streams, the rank may take on 8 possible values, which are respectively from 1 to 8. In this case, the initial set of precoding matrices includes 8 subsets, i.e., a subset corresponding to rank 1, a subset corresponding to rank 2, a subset corresponding to rank 3, … …, and so on. Taking the subset corresponding to rank-3 as an example, the subset may include one or more initial precoding matrices whose column vector number is equal to 3.

The column vector arrangement modes used when the initial precoding matrix in the subset corresponding to the values of different ranks is expanded may be the same or different, and the column vector arrangement modes used when the initial precoding matrix is expanded by the same rank value are the same. For example, the column vector arrangement method used when the initial precoding matrix in the subset corresponding to rank-3 is expanded is different from the column vector arrangement method used when the initial precoding matrix in the subset corresponding to rank-4 is expanded, and the column vector arrangement method used when the initial precoding matrix in the subset corresponding to rank-3 is expanded is the same.

A more specific example is: the subset corresponding to rank 3 includes 2 initial precoding matrices (H)₁，H₂) The 2 initial precoding matrices (H)₁，H₂) The column vector arrangement modes used in the expansion include 3 types: {1,2,3} {2,1,3} {3,1,2}, where the numbers denote the indices of the column vectorsFor example, {2,1,3} denotes: will initial precoding matrix H₁The second column vector in (b) is used as an extended precoding matrix H obtained after extension_{1_2}First column vector of (2), will H₁As the expanded H_{1_2}Second column vector of (2), will H₁The third column vector in (b) is used as the extended H_{1_2}So as to obtain H₁Corresponding 3 extended precoding matrices (H)_{1_1}，H_{1_2}，H_{1_3}). Similarly, the initial precoding matrix H₂Obtaining 3 expanding pre-coding matrixes (H) according to the three column vector expanding modes_{2_1}，H_{2_2}，H_{2_3})。

The subset with rank 4 includes 3 initial precoding matrices (H)₃，H₄，H₅) The column vector arrangement modes used in the extension of the 3 initial precoding matrices include 3 types: {1,2,3,4} {1,3,2,4} {1,4,2,3}, wherein the numbers indicate the indices of the column vectors, are extended as described above, so that H is obtained₃Corresponding 3 extended precoding matrices (H)_{3_1}，H_{3_2}，H_{3_3}). Similarly, the initial precoding matrix H₄Obtaining 3 expanding pre-coding matrixes (H) according to the three column vector expanding modes_{4_1}，H_{4_2}，H_{4_3}) Initial precoding matrix H₅Obtaining 3 expanding pre-coding matrixes (H) according to the three column vector expanding modes_{5_1}，H_{5_2}，H_{5_3})。

For the initial precoding matrix with rank N (i.e. the number of column vectors is equal to N), the column vector arrangement may be N | (N |, denotes the factorial operation of N, and N | ═ N × (N-1) × (N-2) × … × 1). preferably, in the embodiment of the present invention, considering that the agreed column vector arrangement only reflects the allocation information of different column vectors in different codewords, different arrangement orders of precoding column vectors used for precoding data of the same codeword, or precoding column vectors used for two codewords are exchanged, all belonging to the equivalent arrangement.

For example, assume that the number of column vectors of an initial precoding matrix is 3, where the first column vector is mapped to a first codeword and the second and three column vectors are mapped to a second codeword. Theoretically, there are 6 column vector arrangements: {1,2,3}{2,1,3}{3,1,2}{1,3,2}{2,3,1}{3,2,1}. Since the first column vector is mapped to the first codeword and the second and third column vectors are mapped to the second codeword, for {1,2,3} and {1,3,2}, the same column vector is mapped to the first codeword, i.e., the first column vector in the initial precoding matrix is mapped to the first codeword, and the column vectors mapped to the second codeword in the two permutations are both the second and third column vectors in the initial precoding matrix although the permutations are different, so that {1,2,3} and {1,3,2} are treated as equivalent permutations, and one of them is sufficient. Similarly, {2,1,3} and {2,3,1} are equivalent, and {3,1,2} and {3,2,1} are equivalent, so the column vector arrangement can be only three of {1,2,3} {2,1,3} {3,1,2 }. Extended precoding matrix H obtained in {1,2,3} permutation mode_{1_1}And an extended precoding matrix H obtained in a {2,1,3} arrangement_{1_2}For example, it can be seen that H_{1_1}The column vector (the column vector with index number 1 in the initial precoding matrix) mapped to the first code word and H_{1_2}The column vector mapped to the first codeword (the column vector with index number 2 in the initial precoding matrix) and the column vector mapped to the second codeword are different, H_{1_1}Column vectors mapped to the second codeword (column vectors with index numbers 2 and 3 in the initial precoding matrix) and H_{1_2}Wherein the column vectors mapped to the first and second codewords are different; similarly, the rule is also met for any other two extended precoding matrices.

As another example, assume that the number of column vectors of an initial precoding matrix is 4, where the first two column vectors are mapped to a first codeword and the last two column vectors are mapped to a second codeword. For the two column vector arrangements of {1,2,3,4} and {4,3,2,1}, the column vector {1,2} in the precoding matrix corresponding to {1,2,3,4} is mapped to the first codeword, and the column vector {2,1} mapped to the second codeword in the precoding matrix corresponding to {4,3,2,1} is the same, so the two column vector arrangements are equivalent, and one of them is sufficient.

As an example, table 1 shows the column vector arrangement of rank under different values.

TABLE 1

In practical use, in order to prevent the set of extended precoding matrices from being too large, only some of the column vector arrangements listed above may be used as the agreed column vector arrangement. For example, if the number of column vectors of an initial precoding matrix is greater than a set threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.

For example, when the value of the set threshold is 4, for an initial precoding matrix whose column vector number (i.e., rank value) is less than or equal to 4, the calculation of the extended precoding matrix may be performed by using the column vector arrangement manner in table 1; for the initial precoding matrix with the column vector number larger than 4, only the first column vector arrangement mode in table 1 is adopted to calculate the extended precoding matrix, that is, the column vectors do not need to be reordered at this time, and the initial precoding matrix is directly adopted as the extended precoding matrix.

The initial codebook of a part of the ranks can be expanded, and the initial codebooks of other ranks are not expanded and are directly used as the expanded codebooks. For example, the expanded codebook may be obtained by expanding only the initial codebook with Rank within a certain range according to the above rule, and the expanded codebooks of other ranks are the initial codebooks.

Step 302: and the terminal performs CSI measurement according to the extended precoding matrix set.

In this step, the terminal may use an extended precoding matrix in the extended precoding matrix set as a precoding matrix for downlink transmission, and perform measurement of one or more CSI among PMI, RI, and CQI according to the extended precoding matrix set, where the PMI is an index of the extended precoding matrix in the extended precoding matrix set. That is, the terminal may perform CSI measurement based on the assumption that the extended precoding matrix in the extended precoding matrix set is a precoding matrix used for downlink transmission.

The terminal performs the CSI measurement according to the extended precoding matrix set, which may refer to a method of performing the CSI measurement according to the initial precoding matrix. For example, the terminal may select an extended precoding matrix from the extended precoding matrix set according to a certain criterion after estimating channel information according to the cell common pilot. The selected criteria may be to maximize the mutual channel capacity or to maximize the output signal-to-interference-and-noise ratio, etc.

Step 303: and the terminal feeds back the measured CSI to the base station.

In this step, the CSI fed back by the terminal to the base station may include one or a combination of a PMI, an RI (Rank Indication), and a CQI. The PMI reported by the terminal is an index of the corresponding precoding matrix in the extended precoding matrix set. As an example, the terminal calculates channel capacity corresponding to each extended precoding matrix in the extended precoding matrix set, reports an index corresponding to the extended precoding matrix with the largest channel capacity as a PMI to the base station, and reports an RI and a CQI corresponding to the extended precoding matrix to the base station.

Since in the field of wireless communication, CSI is a channel attribute of a communication link, and describes a fading factor of a signal on each transmission path, that is, a value of each element in a channel gain matrix H, such as signal scattering (scattering), fading or fading of environment (fading), distance fading (power fading) and other information. The CSI may adapt the communication system to the current channel conditions, providing a guarantee for high reliability and high rate communication in a multi-antenna system. In the embodiment of the present invention, the terminal may obtain the CSI by using the extended precoding matrix determined from the extended precoding matrix set and the arrangement manner of the data transmission layer corresponding to the precoding matrix.

As can be seen from the above description, the terminal expands the initial precoding matrix set according to the agreed column vector arrangement mode to obtain an expanded precoding matrix set, and performs CSI measurement and feedback according to the expanded precoding matrix set. Because the extended precoding matrix set is obtained on the basis of extending the initial precoding matrix set, and the scale of the extended precoding matrix is larger than that of the initial precoding matrix set, the CSI measurement and feedback are carried out on the basis of the extended precoding matrix set, compared with the CSI measurement and feedback carried out on the basis of the initial precoding matrix set, the CSI determined and fed back by the terminal can reflect the actual channel state better, and the possibility that the SINRs of a plurality of data streams mapped to the same code word are too large in difference is further reduced.

Referring to fig. 4, a CSI feedback process implemented by the base station side provided for the implementation of the present invention may include the following steps:

step 401: and the base station expands the initial pre-coding matrix set according to the agreed column vector arrangement mode to obtain an expanded pre-coding matrix set.

The method for expanding the initial precoding matrix set to obtain the expanded precoding matrix set by the base station according to the agreed column vector arrangement mode is the same as the method for expanding the initial precoding matrix set to obtain the expanded precoding matrix set by the terminal according to the agreed column vector arrangement mode, and is not repeated here.

Step 402: and the base station receives the CSI measured and fed back by the terminal according to the extended precoding matrix set.

The extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by extending the initial precoding matrix set according to the agreed column vector arrangement manner, and the specific method is the same as the corresponding processing procedure in the CQI feedback process at the terminal side in the foregoing embodiment and is not repeated here. The agreed column vector arrangement mode used by the base station is the same as the agreed column vector arrangement mode used by the terminal.

In order to more clearly understand the embodiments of the present invention, a specific implementation process of the above embodiments of the present invention is described in detail below by taking a specific application scenario as an example.

The base station and the terminal agree on an initial codebook (codebook, namely a set of precoding matrices) used for CSI measurement and feedback, where the initial codebook is a pre-agreed fixed codebook, and the initial codebook with rank i has Ni initial precoding matrices, i is 1,2,3, and 4.

The terminal expands the initial codebook based on an agreed column vector arrangement mode to obtain an expanded codebook, where the agreed column vector arrangement modes of codebooks of different ranks are different, and specifically, reference may be made to the column vector arrangement modes corresponding to rank 1,2,3, and 4 in table 1, where the initial codebook and the expanded codebook are the same when rank 1 and rank 2 are used, and the initial precoding matrix in each initial codebook may be expanded into precoding matrices in three expanded codebooks based on different column vector arrangement modes when rank 3 and rank 4 are used.

The terminal carries out CSI measurement based on an expansion codebook, obtains RI, PMI and CQI and reports the RI, the PMI and the CQI to a base station, wherein the PMI indicates the index of a target precoding matrix in the expansion codebook, and PMI feedback signaling overhead corresponding to each RI value (1-4) can be { log2(N1), log2(N2), log2(3 × N3) and log2(3 × N4) }.

And the base station expands the appointed initial codebook according to the same appointed column vector arrangement mode to obtain the same expanded codebook. And after receiving the CSI reported by the terminal, finding out a corresponding precoding matrix from the extended codebook according to the PMI for precoding of downlink transmission.

Based on the same technical concept, the embodiment of the invention also provides a terminal.

Referring to fig. 5, a schematic structural diagram of a terminal according to an embodiment of the present invention is provided, where the terminal can implement the CSI feedback process at the terminal side. As shown, the terminal may include: an extension module 501, a measurement module 502, and a feedback module 503, wherein:

an expanding module 501, configured to expand the initial precoding matrix set according to an agreed column vector arrangement manner to obtain an expanded precoding matrix set;

a measurement module 502, configured to perform CSI measurement according to the extended precoding matrix set;

a feedback module 503, configured to feed back the measured CSI to the base station.

Preferably, the expansion module 501 may be specifically configured to: expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix; and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Preferably, the measurement module 502 may be specifically configured to: and taking an extended precoding matrix in the extended precoding matrix set as a precoding matrix used for downlink transmission, and measuring one or more CSI (channel state information) in a Precoding Matrix Indicator (PMI), a Rank Indicator (RI) and a Channel Quality Indicator (CQI) according to the extended precoding matrix set, wherein the PMI is an index of the extended precoding matrix in the extended precoding matrix set.

Based on the same technical concept, the embodiment of the invention also provides a base station.

Referring to fig. 6, which is a schematic structural diagram of a base station provided in the embodiment of the present invention, the terminal may implement the CSI feedback process at the base station side. As shown, the base station may include: an extension module 601 and a receiving module 602, wherein:

an extension module 601, configured to extend the initial precoding matrix set according to an agreed column vector arrangement manner to obtain an extended precoding matrix set;

a receiving module 602, configured to receive CSI measured and fed back by the terminal according to the extended precoding matrix set, where the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by extending the initial precoding matrix set by the terminal according to the agreed column vector arrangement manner.

Preferably, the expansion module 601 may be specifically configured to: expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix; and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Referring to fig. 7, a schematic structural diagram of a terminal according to an embodiment of the present invention is provided, where the terminal can implement the CSI feedback process at the terminal side. As shown, the terminal may include: a processor 701, a memory 702, a transceiver 703, and a bus interface.

The processor 701 is responsible for managing the bus architecture and general processing, and the memory 702 may store data used by the processor 701 in performing operations. The transceiver 703 is used for receiving and transmitting data under the control of the processor 701.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by processor 701, and various circuits, represented by memory 702, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The processor 701 is responsible for managing the bus architecture and general processing, and the memory 702 may store data used by the processor 701 in performing operations.

The signal processing flow disclosed in the embodiment of the present invention may be applied to the processor 701, or implemented by the processor 701. In implementation, the steps of the signal processing flow may be implemented by integrated logic circuits of hardware or instructions in the form of software in the processor 701. The processor 701 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that may implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 702, and the processor 701 reads the information in the memory 702 and completes the steps of the signal processing flow in combination with the hardware thereof.

Specifically, the processor 701, configured to read the program in the memory 702, executes the following processes:

performing CSI measurement according to the extended precoding matrix set;

the measured CSI is fed back to the base station through the transceiver 703.

Preferably, the processor 701 is specifically configured to: expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix; and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Preferably, the processor 701 is specifically configured to: and taking an extended precoding matrix in the extended precoding matrix set as a precoding matrix used for downlink transmission, and measuring one or more CSI (channel state information) in a Precoding Matrix Indicator (PMI), a Rank Indicator (RI) and a Channel Quality Indicator (CQI) according to the extended precoding matrix set, wherein the PMI is an index of the extended precoding matrix in the extended precoding matrix set.

Referring to fig. 8, which is a schematic structural diagram of a base station according to an embodiment of the present invention, the terminal may implement the CSI feedback process at the base station side. As shown, the base station may include: a processor 801, a memory 802, a transceiver 803, and a bus interface.

The processor 801 is responsible for managing the bus architecture and general processing, and the memory 802 may store data used by the processor 801 in performing operations. The transceiver 803 is used for receiving and transmitting data under the control of the processor 801.

The bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by the processor 801, and various circuits, represented by the memory 802, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The processor 801 is responsible for managing the bus architecture and general processing, and the memory 802 may store data used by the processor 801 in performing operations.

The signal processing flow disclosed in the embodiment of the present invention may be applied to the processor 801 or implemented by the processor 801. In implementation, the steps of the signal processing flow may be implemented by integrated logic circuits of hardware or instructions in the form of software in the processor 801. The processor 801 may be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like that implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 802, and the processor 801 reads the information in the memory 802, and completes the steps of the signal processing flow in combination with the hardware thereof.

Specifically, the processor 801, which is configured to read the program in the memory 802, executes the following processes:

the CSI measured and fed back by the terminal according to the extended precoding matrix set is received through the transceiver 803, wherein the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by the terminal expanding the initial precoding matrix set according to the agreed column vector arrangement mode.

Preferably, the processor 801 is specifically configured to: expanding the initial precoding matrix set according to an agreed column vector arrangement mode for part of initial precoding matrices in the initial precoding matrix set to obtain an expanded precoding matrix; and regarding the rest initial precoding matrixes in the initial precoding matrix set, and taking the rest initial precoding matrixes as corresponding extended precoding matrixes.

Finally, the embodiments of the present invention add different column vector arrangement sequences to the initial precoding matrix set, so that the terminal may traverse mapping from different codewords to data streams when performing CSI feedback, so that the detected SINRs of multiple data streams mapped to the same codeword are relatively close, the phenomenon that the modulation and coding modes of some data streams are too high or too low after the base station performs modulation and coding according to the CQI fed back by the terminal is reduced, and the spectrum efficiency of transmission is improved.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A method for feeding back Channel State Information (CSI), comprising:

the terminal feeds back the measured CSI to the base station;

the terminal expands the initial precoding matrix set according to an agreed column vector arrangement mode, and the method comprises the following steps:

2. The method of claim 1, wherein the initial set of precoding matrices comprises N subsets, each subset corresponding to a value of transmission rank, the number of column vectors of an initial precoding matrix in a subset is equal to the value of transmission rank corresponding to the subset, and N is an integer greater than or equal to 1.

3. The method of claim 2, wherein the same transmission rank value is used for spreading the initial precoding matrices in the same column vector arrangement.

4. The method of claim 1, wherein a column vector mapped to a codeword in one extended precoding matrix among column vectors of any two extended precoding matrices among all extended precoding matrices corresponding to one initial precoding matrix is different from a column vector mapped to any codeword in another extended precoding matrix.

5. The method of claim 1, wherein if the number of column vectors of an initial precoding matrix is greater than a set threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.

6. The method of any of claims 1 to 5, wherein the terminal performs CSI measurements according to the set of extended precoding matrices, comprising:

7. The method as claimed in any one of claims 1 to 5, wherein before the terminal expands the initial precoding matrix set according to the agreed column vector permutation mode, the method further comprises:

8. A method for feeding back Channel State Information (CSI), comprising:

the base station receives CSI measured and fed back by the terminal according to the extended precoding matrix set, wherein the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by the terminal expanding the initial precoding matrix set according to the agreed column vector arrangement mode;

the base station expands the initial precoding matrix set according to the agreed column vector arrangement mode, and the method comprises the following steps:

9. The method of claim 8, wherein the initial set of precoding matrices comprises N subsets, each subset corresponding to a value of transmission rank, the number of column vectors of an initial precoding matrix in a subset is equal to the value of transmission rank corresponding to the subset, and N is an integer greater than or equal to 1.

10. The method of claim 9, wherein column vectors are arranged in the same manner when the initial precoding matrices corresponding to the same transmission rank value are expanded.

11. The method of claim 8, wherein, of all extended precoding matrices corresponding to one initial precoding matrix, any two extended precoding matrices have different column vectors, and one extended precoding matrix has a different column vector mapped to one codeword than another extended precoding matrix has a different column vector mapped to any codeword.

12. The method of claim 8, wherein if the number of column vectors of the initial precoding matrix is greater than a predetermined threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.

13. The method of any of claims 8 to 12, further comprising:

and the base station sends effective precoding matrix indication information to a terminal, wherein the effective precoding matrix indication information is used for indicating an effective precoding matrix in the initial precoding matrix set.

14. A terminal, comprising:

a feedback module, configured to feed back the measured CSI to the base station;

wherein the extension module is specifically configured to:

15. The terminal of claim 14, wherein the initial precoding matrix set comprises N subsets, each subset corresponding to a value of transmission rank, the number of column vectors of the initial precoding matrix in a subset is equal to the value of transmission rank corresponding to the subset, and N is an integer greater than or equal to 1.

16. The terminal of claim 15, wherein column vectors used for spreading initial precoding matrices corresponding to the same transmission rank value are arranged in the same manner.

17. The terminal of claim 14, wherein, of all extended precoding matrices corresponding to one initial precoding matrix, any two extended precoding matrices have different column vectors, and a column vector mapped to a codeword in one extended precoding matrix is different from a column vector mapped to any codeword in another extended precoding matrix.

18. The terminal of claim 14, wherein if the number of column vectors of an initial precoding matrix is greater than a set threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.

19. The terminal according to any of claims 14 to 18, wherein the measurement module is specifically configured to:

and taking an extended precoding matrix in the extended precoding matrix set as a precoding matrix used for downlink transmission, and measuring one or more CSI (channel state information) in a Precoding Matrix Indicator (PMI), a Rank Indicator (RI) and a Channel Quality Indicator (CQI) according to the extended precoding matrix set, wherein the PMI is an index of the extended precoding matrix in the extended precoding matrix set.

20. A base station, comprising:

a receiving module, configured to receive CSI measured and fed back by a terminal according to an extended precoding matrix set, where the extended precoding matrix set on which the terminal performs CSI measurement and feedback is obtained by the terminal expanding the initial precoding matrix set according to the agreed column vector arrangement mode;

wherein the extension module is specifically configured to:

21. The base station of claim 20, wherein the initial set of precoding matrices comprises N subsets, each subset corresponding to a value of transmission rank, the number of column vectors of an initial precoding matrix in a subset is equal to the value of transmission rank corresponding to the subset, and N is an integer greater than or equal to 1.

22. The base station of claim 21, wherein column vectors used for spreading initial precoding matrices corresponding to the same transmission rank value are arranged in the same manner.

23. The base station of claim 20, wherein, of all extended precoding matrices corresponding to one initial precoding matrix, any two extended precoding matrices have different column vectors, and one extended precoding matrix has a different column vector mapped to one codeword than another extended precoding matrix has a different column vector mapped to any codeword.

24. The base station of claim 20, wherein if the number of column vectors of an initial precoding matrix is greater than a predetermined threshold, the extended precoding matrix corresponding to the initial precoding matrix is the same as the initial precoding matrix.