CN111835390A

CN111835390A - Channel measurement method and communication device

Info

Publication number: CN111835390A
Application number: CN201910304861.1A
Authority: CN
Inventors: 陈大庚; 黄宗浩; 庞继勇; 毕晓艳
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-04-16
Filing date: 2019-04-16
Publication date: 2020-10-27
Anticipated expiration: 2039-04-16
Also published as: CN111835390B; WO2020211681A1

Abstract

The application provides a channel measurement method and a communication device. The method comprises the following steps: the network equipment determines a target precoding vector for data transmission based on the K times of received feedback information; and precoding data according to the target precoding vector, and sending the precoded data. The K times of received feedback information are determined based on the K times of sent precoding reference signals, and the K-th time of received feedback information is used for indicating N_kWeight of precoding vector, N_kThe weighted sum of precoding vectors is N_k+1One of the precoding vectors; n is a radical of_kEach precoding vector is used for generating a precoding reference signal transmitted at the kth time, N_k+1Each precoding vector is used for generating a precoding reference signal transmitted at the (k + 1) th time. Through multiple channel measurement and feedback, the precoding vector for data transmission determined by the network equipment is closer to the direction of the terminal equipment, namelyThe data transmission performance is improved.

Description

Channel measurement method and communication device

Technical Field

The present application relates to the field of communications, and more particularly, to a channel measurement method and a communication apparatus.

Background

In a massive multiple-input multiple-output (massive mimo) technology, a network device may reduce interference between multiple users and interference between multiple signal streams of the same user through a precoding technique. Therefore, the signal quality is improved, space division multiplexing is realized, and the frequency spectrum utilization rate is improved.

Currently, a channel measurement method is known. The terminal device may perform channel measurement according to the received reference signal, and determine a precoding vector to be fed back. The reference signal received by the terminal device may be, for example, a precoded reference signal. However, if the precoding vector used by the network device to precode the downlink reference signal is not appropriate, the obtained feedback of the terminal device is not accurate enough, and thus the determined precoding matrix used to precode the downlink data may not be well adapted to the downlink channel, and the data transmission performance is degraded.

Disclosure of Invention

The application provides a channel measurement method and a communication device, which aim to select a reasonable precoding vector to precode a downlink reference signal, so that more accurate feedback of terminal equipment can be obtained.

In a first aspect, a channel measurement method is provided. The method may be performed by a network device, or may be performed by a chip configured in the network device. This is not a limitation of the present application.

Specifically, the method comprises the following steps: determining a target precoding vector for data transmission based on the K times of received feedback information; the K times of received feedback information are determined based on K times of transmitted precoding reference signals, wherein the K-th time of received feedback information is used for indicating N_kWeight of precoding vectors, N_kThe weighted sum of precoding vectors is N_k+1One of the precoding vectors; said N is_kEach precoding vector is used for generating a precoding reference signal sent at the kth time, and N is_k+1The precoding vectors are used for generating precoding reference signals sent for the (k + 1) th time; k is more than or equal to 1, K is more than or equal to 1 and less than or equal to K, and K, K and N_kAnd N_k+1Are all positive integers; pre-coding data to be transmitted according to the target pre-coding vector to obtain pre-coded data; and transmitting the pre-coded data.

Therefore, the terminal device can perform channel measurement and feedback based on the precoded reference signals transmitted by the network device multiple times. The precoding reference signal used by the precoding reference signal sent by the network device each time refers to the information fed back by the terminal device at the previous time, so that the precoding reference signal can be closer to the direction of the terminal device, and the obtained feedback of the terminal device is more accurate. In addition, the network device may determine a precoding vector used for precoding data based on the last feedback of the terminal device, and the determined precoding vector may be considered as a precoding direction closest to the terminal device direction in the currently obtained channel measurement result, thereby being beneficial to improving data transmission performance.

With reference to the first aspect, in some possible implementation manners of the first aspect, N is_k+1The remaining N of the precoding vectors_k+1-1 precoding vector is a precoding vector of a predetermined set of precoding vectors.

In N_k+1If the number of the channel measurements is greater than 1, the network device may select N, which has not been used to precode the reference signal in the previous channel measurement or channel measurements, from a predetermined set of precoding vectors_k+1-1 precoding vectors, dividing the N_k+1-1 precoding vectors and said N_kThe weighted sum of the precoding vectors is used to precode the reference signal transmitted at the (k + 1) th time to obtain the N_k+1The weights of the precoding vectors, and the feedback information obtained thereby can be used for precoding the reference signal transmitted at the (k + 2) th time. By traversing through the set of precoding vectors, different precoding vectors can be used to search for the direction of the terminal device. By passing multiple timesIteratively, the vector used by the network device to precode the reference signal may be closer to the direction of the terminal device, and thus the determined precoding vector for data transmission is also closer to the direction of the terminal device.

With reference to the first aspect, in some possible implementations of the first aspect, the method further includes: generating a first precoding vector set based on the I-th received feedback information in the K received feedback information, wherein the I-th received feedback information is used for indicating N_IWeight of precoding vectors, N_IThe precoding vectors are used for generating precoding reference signals sent for the I time; the first set of precoding vectors comprises N_IWeighted sum of precoding vectors and their weight determination

And based on

A plurality of vectors constructed; i is more than or equal to 1 and less than or equal to K, and I is a positive integer.

Therefore, after the pre-configured set of pre-coding vectors or the pre-determined set of pre-coding vectors are traversed, the network device may further update the currently used set of pre-coding vectors (e.g., the second set of pre-coding vectors described below) based on the feedback information of the terminal device. Since the update is updated based on the feedback information of the terminal device, the updated first precoding vector set is closer to the direction of the terminal device than the currently used precoding vector set, and therefore the direction of the terminal device can be searched in a smaller range to obtain more accurate feedback.

With reference to the first aspect, in some possible implementations of the first aspect, the precoding vector used for generating the precoded reference signal sent I +1 th time is a precoding vector in the first set of precoding vectors; at least part of precoding vectors used for generating the precoding reference signals of the previous I times of transmission are vectors in a second predetermined precoding vector set; the second set of precoding vectors is different from the first set of precoding vectors.

The second set of precoding vectors may be a pre-configured set of precoding vectors, or may be a set of precoding vectors obtained through one or more updates. This is not a limitation of the present application. Due to the fact that the second precoding vector is updated, the precoding vector in the first precoding vector set obtained through updating is at least partially different from the precoding vector in the second precoding vector set.

With reference to the first aspect, in some possible implementations of the first aspect, the first set of precoding vectors includes at least T precoding vectors. Generating a first precoding vector set based on the ith received feedback information in the K received feedback information, including: determining the N based on the I-th received feedback information in the K received feedback information_IWeighted sum of precoding vectors

A precoding vector in the first set of precoding vectors; based on

Generating T-1 Givens rotation matrixes G (c, T, theta) or G (T, c, theta) in a row where the element b with the maximum medium amplitude is located; wherein c represents b in

C is a positive integer, and c is more than or equal to 1 and less than or equal to T; t is an integer value from 1 to T, T is not equal to c, and theta represents a rotation angle; generating remaining T-1 vectors of the first set of precoding vectors based on the T-1 Givens rotation matrices G (c, T, θ) or G (T, c, θ).

In the weighted sum

The two-bit vector formed by the element with the maximum amplitude and other elements is slightly rotated, namely, a plurality of directions are expanded based on the direction with the strongest intensity. I.e. based on a more accurate search of the orientation of the terminal device within a small range.

With reference to the first aspect, in some possible implementations of the first aspect, the feedback information received K times is used to determine a precoding vector used for transmitting the data through an ith transmission layer of the L transmission layers; one or more transmission layers in the L transmission layers are used for transmitting the data, L is more than or equal to 1 and less than or equal to L, L is more than or equal to 1, and L and L are integers.

That is, some or all of the L transport layers may be used to transmit data to the same terminal device. The feedback information received for the K times can be used to determine a precoding vector for precoding data transmitted through one of the transmission layers. The L transport layers may be determined by the number of transmit antennas configured by the network device. The number of transmit antennas may be referred to as the number of independent transmit and receive units (txrus).

With reference to the first aspect, in some possible implementation manners of the first aspect, J transport layers of the L transport layers are used for transmitting data, where the J transport layers include the L-th transport layer and J-1 transport layers other than the L-th transport layer, J is greater than or equal to 2 and less than or equal to L, and J is an integer. The method further comprises the following steps: determining a precoding vector used for transmitting data on an mth transmission layer based on the feedback information received K times, wherein the jth transmission layer is any one of the J-1 transmission layers; the feedback information received for the K times is determined by precoding reference signals sent on the jth transmission layer for the K times; the feedback information received at the K time in the feedback information received at the K time is used for indicating

A weight of a precoding vector, the

A weighted sum of precoding vectors of

One of the precoding vectors; the above-mentioned

Each precoding vector is used for generating a precoding reference signal sent by the jth transmission layer for the kth time

The precoding vectors are used for generating precoding reference signals sent by the jth transmission layer for the (k + 1) th time; j is more than or equal to 1 and less than or equal to J-1, and J is an integer.

In the J transmission layers, precoding vectors used for precoding data transmitted on each transmission layer may be determined according to feedback of the terminal device based on the transmission layer. The terminal device may carry feedback for multiple transport layers through the feedback information transmitted at one time. The network device is facilitated to determine precoding vectors for precoding data transmitted by each transmission layer based on feedback of each transmission layer.

With reference to the first aspect, in some possible implementations of the first aspect, the method further includes: receiving a precoding vector set reset indication which is used for indicating that channel measurement is carried out based on the reset precoding vector set.

Therefore, the terminal device can recommend the network device to reset the precoding vector set and further perform channel measurement again under the condition of high-speed movement or channel mutation, so that the direction of the terminal device can be searched quickly and the precoding vector which is matched with the channel and used for data transmission can be determined.

In a second aspect, a channel measurement method is provided. The method may be performed by the terminal device, or may be performed by a chip configured in the terminal device. This is not a limitation of the present application.

Specifically, the method comprises the following steps: generating feedback information based on the received precoding reference signal, the feedback information indicating weights of one or more precoding vectors, the one or more precoding vectors being precoding vectors used to generate the precoding reference signal; and sending the feedback information, wherein the feedback information is used for determining precoding vectors used for data transmission on each transmission layer.

With reference to the second aspect, in some possible implementation manners of the second aspect, the generating feedback information based on the received precoded reference signal includes: determining weights of the one or more precoding vectors based on a predetermined observation matrix W and the received precoding reference signals; wherein, W is S (U Λ)^-1(ii) a U and Λ are matrixes obtained by singular value decomposition of a channel matrix H; u is an R-dimensional unitary matrix, and Lambda is an R-dimensional diagonal matrix; s is a matrix of Z rows and R columns, each row in S comprises R-1 zero elements, and the Z-th element in the Z-th row in S is 1; z is more than or equal to 1 and less than or equal to Z, Z represents the rank of a channel matrix H, R represents the number of receiving antennas, and Z, Z, T and R are integers; generating the feedback information based on weights of the one or more precoding vectors.

The terminal equipment can accurately calculate the weight of each precoding vector based on the observation matrix and the received precoding reference signal, and feeds the weight back to the network equipment.

It should be understood that calculating the weight of each precoding vector based on the observation matrix is only one possible implementation and should not constitute any limitation to the present application. The specific implementation manner of determining each precoding vector by the terminal device is not limited in the present application.

With reference to the second aspect, in some possible implementation manners of the second aspect, the method further includes:

and sending a precoding vector set resetting indication, wherein the precoding vector set resetting indication is used for indicating that channel measurement is carried out based on the reset precoding vector set.

In a third aspect, a communication device is provided, which includes various means or units for performing the method of the first aspect and any one of the possible implementations of the first aspect.

In a fourth aspect, a communications apparatus is provided that includes a processor. The processor is coupled to the memory and is operable to execute instructions in the memory to implement the method of any one of the possible implementations of the first aspect and the first aspect. Optionally, the communication device further comprises a memory. Optionally, the communication device further comprises a communication interface, the processor being coupled to the communication interface.

In one implementation, the communication device is a terminal device. When the communication device is a terminal device, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the communication device is a chip configured in the terminal equipment. When the communication device is a chip configured in a terminal device, the communication interface may be an input/output interface.

Alternatively, the transceiver may be a transmit-receive circuit. Alternatively, the input/output interface may be an input/output circuit.

In a fifth aspect, a communication device is provided, which comprises various modules or units for performing the method of the second aspect and any one of the possible implementations of the second aspect.

In a sixth aspect, a communications apparatus is provided that includes a processor. The processor is coupled to the memory and is operable to execute the instructions in the memory to implement the method of any one of the possible implementations of the second aspect and the second aspect. Optionally, the communication device further comprises a memory. Optionally, the communication device further comprises a communication interface, the processor being coupled to the communication interface.

In one implementation, the communication device is a network device. When the communication device is a network device, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the communication device is a chip configured in the network device. When the communication device is a chip configured in a network device, the communication interface may be an input/output interface.

In a seventh aspect, a processor is provided, including: input circuit, output circuit and processing circuit. The processing circuit is configured to receive a signal through the input circuit and transmit a signal through the output circuit, so that the processor performs the method of any one of the possible implementations of the first to second aspects and the first to second aspects.

In a specific implementation process, the processor may be one or more chips, the input circuit may be an input pin, the output circuit may be an output pin, and the processing circuit may be a transistor, a gate circuit, a flip-flop, various logic circuits, and the like. The input signal received by the input circuit may be received and input by, for example and without limitation, a receiver, the signal output by the output circuit may be output to and transmitted by a transmitter, for example and without limitation, and the input circuit and the output circuit may be the same circuit that functions as the input circuit and the output circuit, respectively, at different times. The embodiment of the present application does not limit the specific implementation manner of the processor and various circuits.

In an eighth aspect, a processing apparatus is provided that includes a processor and a memory. The processor is configured to read instructions stored in the memory, and may receive a signal via the receiver and transmit a signal via the transmitter to perform the method of any one of the possible implementations of the first to second aspects and the first to second aspects.

Optionally, the number of the processors is one or more, and the number of the memories is one or more.

Alternatively, the memory may be integral to the processor or provided separately from the processor.

In a specific implementation process, the memory may be a non-transient memory, such as a Read Only Memory (ROM), which may be integrated on the same chip as the processor, or may be separately disposed on different chips.

It will be appreciated that the associated data interaction process, for example, sending the indication information, may be a process of outputting the indication information from the processor, and receiving the capability information may be a process of receiving the input capability information from the processor. In particular, data output by the processor may be output to a transmitter and input data received by the processor may be from a receiver. The transmitter and receiver may be collectively referred to as a transceiver, among others.

The processing means in the above-mentioned eighth aspect may be one or more chips. The processor in the processing device may be implemented by hardware or may be implemented by software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, or the like; when implemented in software, the processor may be a general-purpose processor implemented by reading software code stored in a memory, which may be integrated with the processor, located external to the processor, or stand-alone.

In a ninth aspect, there is provided a computer program product, the computer program product comprising: a computer program (which may also be referred to as code, or instructions), which when executed, causes a computer to perform the method of any of the possible implementations of the first to second aspects and the first to second aspects described above.

A tenth aspect provides a computer-readable medium storing a computer program (which may also be referred to as code or instructions) which, when run on a computer, causes the computer to perform the method of any one of the possible implementations of the first to second aspects and the first to second aspects described above.

In an eleventh aspect, a communication system is provided, which includes the foregoing network device and terminal device.

Drawings

Fig. 1 is a schematic diagram of a communication system suitable for a channel measurement method provided in an embodiment of the present application;

fig. 2 is a schematic flow chart of a channel measurement method provided in an embodiment of the present application;

fig. 3 is a schematic block diagram of a communication device provided by an embodiment of the present application;

fig. 4 is a schematic structural diagram of a terminal device provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of a network device according to an embodiment of the present application.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

The technical scheme of the embodiment of the application can be applied to various communication systems, for example: a global system for mobile communications (GSM) system, a Code Division Multiple Access (CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system, a General Packet Radio Service (GPRS), a long term evolution (long term evolution, LTE) system, a LTE Frequency Division Duplex (FDD) system, a LTE Time Division Duplex (TDD), a Universal Mobile Telecommunications System (UMTS), a Worldwide Interoperability for Microwave Access (WiMAX) communication system, a future fifth generation (5G) or New Radio (NR) system, and the like.

For the convenience of understanding the embodiments of the present application, a communication system applicable to the embodiments of the present application will be first described in detail by taking the communication system shown in fig. 1 as an example. Fig. 1 is a schematic diagram of a communication system 100 suitable for use in the channel measurement method of the embodiments of the present application. As shown in fig. 1, the communication system 100 may include at least one network device, such as the network device 110 shown in fig. 1; the communication system 100 may also include at least one terminal device, such as the terminal device 120 shown in fig. 1. Network device 110 and terminal device 120 may communicate via a wireless link. Each communication device, such as network device 110 or terminal device 120, may be configured with multiple antennas. For each communication device in the communication system 100, the configured plurality of antennas may include at least one transmit antenna for transmitting signals and at least one receive antenna for receiving signals. Accordingly, communication between communication devices in the communication system 100, such as between the network device 110 and the terminal device 120, may be via multiple antenna techniques.

It should be understood that the network device in the communication system may be any device having a wireless transceiving function. The network devices include, but are not limited to: evolved Node B (eNB), Radio Network Controller (RNC), Node B (NB), Base Station Controller (BSC), Base Transceiver Station (BTS), home base station (e.g., home evolved Node B, or home Node B, HNB), baseband unit (BBU), Access Point (AP), wireless relay Node, wireless backhaul Node, Transmission Point (TP), or Transmission and Reception Point (TRP) in a wireless fidelity (WiFi) system, and the like, and may also be 5G, e.g., NR, a gbb in a system, or a transmission point (TRP or TP), one or a group of base stations in a 5G system may include multiple antennas, or may also constitute a panel of a network, e.g., a panel of a network, or a BBU, or a Distributed Unit (DU), etc.

In some deployments, the gNB may include a Centralized Unit (CU) and a DU. The gNB may further include an Active Antenna Unit (AAU). The CU implements part of the function of the gNB, and the DU implements part of the function of the gNB, for example, the CU is responsible for processing non-real-time protocols and services, and implementing functions of a Radio Resource Control (RRC) layer and a packet data convergence layer (PDCP) layer. The DU is responsible for processing a physical layer protocol and a real-time service, and implements functions of a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. The AAU implements part of the physical layer processing functions, radio frequency processing and active antenna related functions. Since the information of the RRC layer eventually becomes or is converted from the information of the PHY layer, the higher layer signaling, such as the RRC layer signaling, may also be considered to be transmitted by the DU or by the DU + AAU under this architecture. It is to be understood that the network device may be a device comprising one or more of a CU node, a DU node, an AAU node. In addition, the CU may be divided into network devices in an access network (RAN), or may be divided into network devices in a Core Network (CN), which is not limited in this application.

It should also be understood that terminal equipment in the wireless communication system may also be referred to as User Equipment (UE), an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user equipment. The terminal device in the embodiment of the present application may be a mobile phone (mobile phone), a tablet (pad), a computer with a wireless transceiving function, a Virtual Reality (VR) terminal device, an Augmented Reality (AR) terminal device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in telemedicine (remote), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety (transportation safety), a wireless terminal in smart city (smart city), a wireless terminal in smart home (smart home), a mobile terminal configured in a vehicle, and the like. The embodiments of the present application do not limit the application scenarios.

It should also be understood that fig. 1 is a simplified schematic diagram that is merely illustrated for ease of understanding, and that other network devices or other terminal devices, which are not shown in fig. 1, may also be included in the communication system 100.

In order to facilitate understanding of the embodiments of the present application, the following is a brief description of the processing procedure of the downlink signal at the physical layer before transmission. It should be understood that the processing of the downstream signal described below may be performed by the network device, or may be performed by a chip configured in the network device. For convenience of description, hereinafter, collectively referred to as network devices.

The network device may process a codeword (code word) on a physical channel. Where the codeword may be coded bits that are encoded (e.g., including channel coding). The codeword is scrambled (scrambling) to generate scrambled bits. The scrambled bits are modulation mapped (modulation mapping) to obtain modulation symbols. The modulation symbols are mapped to a plurality of layers (layers), or transport layers, through layer mapping (layermapping). The modulated symbols after layer mapping are precoded (precoding) to obtain precoded signals. The precoded signal is mapped to a plurality of Resource Elements (REs) after mapping the precoded signal to the REs. These REs are then modulated by Orthogonal Frequency Division Multiplexing (OFDM) and transmitted through an antenna port (antenna port).

It should be understood that the above-described processing procedure for the downlink signal is only an exemplary description, and should not limit the present application in any way. For the processing procedure of the downlink signal, reference may be made to the prior art, and a detailed description of the specific procedure is omitted here for brevity.

In order to facilitate understanding of the embodiments of the present application, the following description is briefly made of terms related to the embodiments of the present application.

1. The precoding technology comprises the following steps: under the condition of known channel state, a transmitting device (such as a network device) can process a signal to be transmitted by means of a precoding matrix matched with the channel state, so that the signal to be transmitted after precoding is adaptive to a channel, and the complexity of eliminating the influence between channels by a receiving device (such as a terminal device) is reduced. Therefore, by performing precoding processing on a signal to be transmitted, received signal quality (e.g., signal to interference plus noise ratio (SINR)) is improved. Therefore, by using the precoding technique, the transmission between the sending device and the multiple receiving devices can be realized on the same time-frequency resource, that is, multi-user multiple input multiple output (MU-MIMO) is realized.

It should be understood that the related description regarding the precoding technique is merely exemplary for ease of understanding and is not intended to limit the scope of the embodiments of the present application. In a specific implementation process, the sending device may also perform precoding in other manners. For example, when the channel information (for example, but not limited to, the channel matrix) cannot be obtained, precoding is performed using a preset precoding matrix or a weighting processing method. For brevity, the detailed contents thereof are not described herein again.

2. Precoding reference signals: also known as beamformed (beamformed) reference signals. The beamformed reference signal may be a reference signal that has undergone precoding processing, and may be similar to a Class B (Class B) reference signal in the LTE protocol. In contrast, a reference signal that has not been precoded may be similar to a Class a (Class a) reference signal in the LTE protocol.

In the embodiment of the present application, for convenience of distinction and explanation, a precoded reference signal is referred to as a precoded reference signal; reference signals that are not precoded are simply referred to as reference signals.

It should be understood that the reference signals referred to in the embodiments of the present application may be reference signals for channel measurement. For example, the reference signal may be a channel state information reference signal (CSI-RS) or a Sounding Reference Signal (SRS). It should be understood that the above list is merely exemplary and should not constitute any limitation of the present application, which does not exclude the possibility of defining other reference signals in future protocols to achieve the same or similar functionality.

3. Antenna port (antenna port): referred to as a port for short. Which may be understood as a virtual antenna identified by the receiving device. Or spatially distinguishable transmit antennas. One antenna port may be configured for each virtual antenna, each virtual antenna may be a weighted combination of multiple physical antennas, each antenna port may correspond to one reference signal, and thus, each antenna port may be referred to as a port of one reference signal. In the embodiment of the present application, an antenna port may refer to a port of a reference signal after being precoded.

In the embodiments of the present application, the antenna port may refer to a transmission antenna port. For example, the reference signal for each port may be a reference signal that is not precoded. The antenna port may also refer to a reference signal port after precoding, for example, the reference signal of each port may be a precoded reference signal obtained by precoding the reference signal based on one precoding vector. The signal of each port may be transmitted through one or more Resource Blocks (RBs).

The transmitting antenna port may also be referred to as a transmitting antenna for short. Specifically, the present invention may refer to an actual independent transceiver unit (TxRU). In the embodiment of the present application, the number of the transmitting antenna ports may be equal to the number of the transceiver units. It can be understood that if the reference signal is precoded, the port number may refer to the reference signal port number, which may be smaller than the transmit antenna port number. Therefore, the dimension reduction of the transmitting antenna port can be realized by precoding the reference signal, thereby achieving the purpose of reducing the pilot frequency overhead.

In the embodiments shown below, the specific meaning expressed by a port may be determined according to the specific embodiment.

4. Channel matrix and equivalent channel matrix: the receiving end may determine the channel through a variety of possible implementations. For example, the receiving end may perform channel estimation according to the received reference signal; for another example, the receiving end may estimate the channel based on reciprocity of the uplink and downlink channels. This is not a limitation of the present application.

Taking downlink channel estimation as an example, the terminal device may estimate the downlink channel according to the received reference signal. This downlink channel may be denoted as H, for example. The downlink channel may be represented, for example, as a matrix with dimension R × T. Where R is the number of receive antennas, and T is the number of transmit antenna ports, or TxRU. R and T are both positive integers.

If the network device precodes the reference signal, the terminal device may estimate the downlink channel according to the received precoded reference signal. The downlink channel estimated by the terminal device from the precoded reference signal is actually a precoded channel, and may be referred to as an equivalent channel. If the precoding vector is b, the equivalent channel estimated by the terminal device can be denoted as H_effThen H is_effHb. The precoding vector is a vector with dimension of T multiplied by 1. It can be seen that, when the network device precodes the reference signal based on one precoding vector, the dimension of the equivalent channel estimated by the terminal device is R × 1. Namely, the dimension reduction of the transmitting antenna port is realized.

5. Precoding vector and precoding vector set: in the embodiment of the present application, the precoding vector refers to a vector for precoding a reference signal. The precoding vector may be selected from a predetermined set of precoding vectors. The set of precoding vectors may include a plurality of selectable precoding vectors. In addition, in the embodiment of the present application, the precoding vector in the precoding vector set may be updated along with the feedback of the terminal device, so as to adapt to the change of the channel and obtain more accurate feedback of the terminal device.

The precoding vector may be, for example, a column vector of length T. The set of precoding vectors may include T column vectors of length T. The T column vectors may be orthogonal to each other two by two. For example, the T column vectors may be vectors taken from a Discrete Fourier Transform (DFT) matrix.

In the embodiment of the present application, the precoding vector sometimes refers to a precoding vector used for precoding a reference signal, and sometimes refers to a precoding vector used for precoding data to be transmitted. The specific meaning of which in different scenarios will be understood by the skilled person. In the following embodiments, for convenience of distinction and understanding, a precoding vector used for precoding a reference signal is denoted by b, and a precoding vector used for precoding data to be transmitted is denoted by p. However, this is indicated by different letters for the sake of distinction only and should not be construed as limiting the present application in any way.

6. Precoding Matrix Indicator (PMI): taking downlink channel measurement as an example, in a general case, the terminal device may carry a precoding matrix to be fed back, which is determined based on the channel measurement, in a Channel State Information (CSI) report through a PMI, so that the network device determines a precoding vector for each transmission layer when transmitting data through one or more transmission layers according to the PMI, or determines a precoding matrix for data transmission according to the PMI.

In this embodiment of the present application, the terminal device may perform channel estimation based on the received precoding reference signal of each port, so as to obtain an equivalent channel corresponding to each port. The terminal device may feed back an equivalent channel obtained by performing channel estimation based on the precoding reference signal of each port to the network device through the weight of the precoding vector. The method and the device are convenient for the network device to know the weight of each precoding vector used for precoding the reference signal, so that the precoding vector used for precoding the data to be transmitted on each transmission layer can be determined, and the method and the device can also be used for updating the precoding vector when precoding the reference signal next time.

It should be noted that, when the network device determines the precoding matrix for data transmission based on the PMI, the precoding matrix may be determined directly based on the feedback of the terminal device, or the precoding matrix finally used for downlink data transmission may be obtained through some beamforming methods, for example, including Zero Forcing (ZF), minimum mean-squared error (MMSE), maximum signal-to-leakage-and-noise (SLNR), and the like. This is not a limitation of the present application. It should be understood that the beamforming methods listed above are only examples and should not constitute any limitation to the present application. The precoding matrix used for data transmission referred to in the following may refer to a precoding matrix determined based on the channel measurement method provided in the present application.

7. Transport layer (layer): also called transport stream. The number of transmission layers used for data transmission between the network device and the terminal device may be determined by the rank (rank) of the channel matrix. The terminal device may determine the number of transmission layers according to a channel matrix obtained by channel estimation. For example, the precoding matrix may be determined by performing Singular Value Decomposition (SVD) on the channel matrix or a covariance matrix of the channel matrix. In the SVD process, different transport layers may be distinguished according to the size of the eigenvalues. For example, the precoding vector determined by the eigenvector corresponding to the largest eigenvalue may be associated with the 1 st transmission layer, and the precoding vector determined by the eigenvector corresponding to the smallest eigenvalue may be associated with the L-th transmission layer. That is, the eigenvalues corresponding to the 1 st to L-th transport layers decrease in sequence.

It should be understood that distinguishing between different transport layers based on characteristic values is only one possible implementation and should not constitute any limitation to the present application. For example, the protocol may also define other criteria for distinguishing the transport layers in advance, which is not limited in this application.

In order to obtain better signal transmission quality, a transmitting end wants to obtain a more accurate channel state, so as to process a signal to be transmitted by using a precoding matrix matched with the channel state, thereby achieving the purposes of eliminating inter-channel interference and improving signal quality.

Take downlink transmission as an example. In some modes, such as Time Division Duplex (TDD) mode, the uplink and downlink channels transmit signals on different time domain resources on the same frequency domain resource. The channel fading experienced by the signals on the uplink and downlink channels can be considered to be the same over a relatively short time (e.g., the coherence time of the channel propagation). This is the reciprocity of the uplink and downlink channels. Based on reciprocity of the uplink and downlink channels, the network device may measure the uplink channel according to an uplink reference signal, such as a Sounding Reference Signal (SRS). And the downlink channel can be estimated according to the uplink channel, so that a precoding matrix for downlink transmission can be determined.

However, in other modes, such as a Frequency Division Duplex (FDD) mode, since the frequency band interval of the uplink and downlink channels is much larger than the coherence bandwidth, the uplink and downlink channels do not have complete reciprocity, and the uplink channel may not be able to adapt to the downlink channel when the uplink channel is used to determine the precoding matrix for downlink transmission. If the network device still estimates the downlink channel according to the uplink channel measured by the uplink reference signal, the estimated downlink channel may not be accurate. Therefore, the precoding matrix used for data transmission determined by the network device based on the estimated downlink channel may also be adapted to the true downlink channel. Eventually leading to a degradation of data transmission quality and a degradation of system performance.

Based on this, the application provides a channel measurement method, which is expected to obtain a more accurate channel state between a sending end and a receiving end, so that a reasonable precoding matrix can be selected to precode data to be transmitted, thereby improving data transmission quality and improving system performance.

To facilitate understanding of the embodiments of the present application, the following description is made before describing the embodiments of the present application.

First, for the convenience of understanding and explanation, the main parameters involved in the present application are first described as follows:

l: the number of transmission layers that the network device can use. The number of transmission layers that can be used by the network device may be determined by the number of transmit antenna ports configured by the network device. The number of transmit antenna ports referred to herein may be referred to as the TxRU number. In the embodiment of the application, L is more than or equal to 1, and L is an integer; the L transport layers may include, for example, a first transport layer through an L-th transport layer.

Z: the number of transmission layers that can be used when the network device communicates with a terminal device. I.e. the rank of the channel matrix. Z may be determined by the channel matrix. The number of transmission layers that can be used when the network device communicates with the terminal device may be determined by the number of transmit antenna ports configured by the network device and the number of receive antennas configured by the terminal device. For example, Z may be less than or equal to the smaller of the number of transmit antenna ports configured by the network device and the number of receive antennas configured by the terminal device. In the embodiment of the application, L is more than or equal to Z and more than or equal to 1, and Z is a positive integer.

T: the number of transmitting antenna ports, T being a positive integer;

r: the number of receiving antennas, R is a positive integer.

Second, in the present embodiment, for convenience of description, when referring to numbering, numbering may be continued from 1. For example, the L transport layers may include the 1 st transport layer to the L transport layer, and so on, which are not illustrated one by one here. Of course, the specific implementation is not limited to this, and for example, the numbers may be continuously numbered from 0. It should be understood that the above descriptions are provided for convenience of describing the technical solutions provided by the embodiments of the present application, and are not intended to limit the scope of the present application.

Third, in the embodiments of the present application, a plurality of places relate to transformation of matrices and vectors. For ease of understanding, a unified description is provided herein. The superscript T denoting transposition, e.g. A^TRepresents a transpose of a matrix (or vector) a; the superscript H denotes a conjugate transpose, e.g., A^HRepresents the conjugate transpose of matrix (or vector) a; the upper corner marks represent conjugation, e.g. A^*Representing the conjugate of matrix (or vector) a. Hereinafter, the description of the same or similar cases will be omitted for the sake of brevity.

Fourth, in the embodiments of the present application, "for indicating" may include for direct indicating and for indirect indicating. For example, when a certain indication information is described as the indication information I, the indication information may be included to directly indicate I or indirectly indicate I, and does not necessarily represent that I is carried in the indication information.

If the information indicated by the indication information is referred to as information to be indicated, in a specific implementation process, there are many ways of indicating the information to be indicated, for example, but not limited to, directly indicating the information to be indicated, such as the information to be indicated itself or an index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein an association relationship exists between the other information and the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other part of the information to be indicated is known or predetermined. For example, the indication of the specific information may be implemented by means of a predetermined arrangement order of the respective information (e.g., protocol specification), thereby reducing the indication overhead to some extent. Meanwhile, the universal parts of all information can be identified and indicated in a unified mode, so that the indicating overhead caused by independently indicating the same information is reduced. For example, it will be understood by those skilled in the art that the precoding matrix is composed of precoding vectors, and that each precoding vector in the precoding matrix may have the same components in terms of composition or other attributes.

The specific indication method may be any of various existing indication methods, such as, but not limited to, the above indication methods, various combinations thereof, and the like. The specific details of various indication modes can refer to the prior art, and are not described in detail herein. As can be seen from the above description, when a plurality of information of the same type are required to be indicated, for example, different information may be indicated differently. In a specific implementation process, a required indication manner may be selected according to a specific need, and the indication manner selected in the embodiment of the present application is not limited, so that the indication manner related to the embodiment of the present application should be understood to cover various methods that enable a party to be indicated to obtain information to be indicated.

In addition, other equivalent forms of the information to be indicated may exist, for example, a row vector may be represented as a column vector, a matrix may be represented by a transposed matrix of the matrix, a matrix may also be represented as a vector or an array, the vector or the array may be formed by connecting each row vector or column vector of the matrix, a kronecker product of two vectors may also be represented as a product of one vector and a transposed vector of another vector, and the like. The technical solutions provided in the embodiments of the present application should be understood to cover various forms. For example, reference to some or all of the features in the embodiments of the present application should be understood to encompass various manifestations of such features.

The information to be indicated may be sent together as a whole, or may be sent separately by dividing into a plurality of pieces of sub information, and the sending periods and/or sending timings of these pieces of sub information may be the same or different. Specific transmission method this application is not limited. The sending period and/or sending timing of the sub information may be predefined, for example, predefined according to a protocol, or may be configured by the transmitting end device by sending configuration information to the receiving end device. The configuration information may include, for example and without limitation, one or a combination of at least two of radio resource control signaling, such as RRC signaling, MAC layer signaling, such as MAC-CE signaling, and physical layer signaling, such as Downlink Control Information (DCI).

Fifth, in the embodiments shown below, the first, second and various numerical numbers are merely for convenience of description and are not intended to limit the scope of the embodiments of the present application. E.g. to distinguish between different sets of precoding vectors, etc.

Sixth, "predefined" or "pre-configured" may be implemented by pre-saving a corresponding code, table or other means that can be used to indicate related information in a device (for example, including a terminal device and a network device), and the specific implementation manner of the present application is not limited thereto. Wherein "saving" may refer to saving in one or more memories. The one or more memories may be separate devices or may be integrated in the encoder or decoder, the processor, or the communication device. The one or more memories may also be provided as a portion of a stand-alone device, a portion of which is integrated into a decoder, a processor, or a communication device. The type of memory may be any form of storage medium and is not intended to be limiting of the present application.

Seventh, the "protocol" referred to in the embodiments of the present application may refer to a standard protocol in the communication field, and may include, for example, an LTE protocol, an NR protocol, and a related protocol applied in a future communication system, which is not limited in the present application.

Eighth, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, and c, may represent: a, or, b, or, c, or, a and b, or, a and c, or, b and c, or, a, b and c. Wherein a, b and c may be single or plural respectively.

The channel measurement method provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings.

The method provided by the embodiment of the application can be applied to a system for communication through a multi-antenna technology. Such as the communication system 100 shown in fig. 1. The communication system may include at least one network device and at least one terminal device. The network device and the terminal device can communicate through a multi-antenna technology.

It should be understood that the method provided by the embodiment of the present application is not limited to the communication between the network device and the terminal device, and may also be applied to the communication between the terminal device and the terminal device, and the like. The application does not limit the application scenario of the method. In the embodiments shown below, the channel measurement method provided in the embodiments of the present application is described in detail by taking an interaction between a network device and a terminal device as an example, only for convenience of understanding and explanation.

It should also be understood that the embodiments shown below do not particularly limit the specific structure of the execution subject of the method provided by the embodiments of the present application, as long as the communication can be performed according to the method provided by the embodiments of the present application by running the program recorded with the code of the method provided by the embodiments of the present application, for example, the execution subject of the method provided by the embodiments of the present application may be a terminal device or a network device, or a functional module capable of calling the program and executing the program in the terminal device or the network device.

Fig. 2 is a schematic flow chart of a channel measurement method 200 provided by an embodiment of the present application, shown from the perspective of device interaction. Specifically, the method 200 shown in fig. 2 is an example of downlink channel measurement. As shown, the method 200 may include steps 210 through 270. The steps in method 200 are described in detail below.

In step 210, the network device sends a precoded reference signal, where the precoded reference signal is obtained by precoding a reference signal based on N precoding vectors.

Wherein N is an integer of 1 or more. In particular, the N precoding vectors may be determined from a predetermined set of precoding vectors, for example. The precoding vector set may be, for example, a pre-configured precoding vector set, or a precoding vector set obtained after updating the pre-configured precoding vector set according to feedback information from the terminal device. This is not a limitation of the present application.

The network device precodes the reference signal based on the N precoding vectors, and the obtained precoded reference signal may correspond to the N reference signal ports. Each reference signal port corresponds to a precoding vector. That is, the reference signal that the terminal device can recognize is a precoded reference signal of N ports. Since the specific process of the network device precoding the reference signal based on the precoding vector may refer to the prior art, for brevity, it is not described here again.

In one possible design, the network device may precode reference signals transmitted through each of the L transmission layers based on the N precoding vectors. In other words, the precoded reference signal transmitted through any one of the L transmission layers may be obtained by precoding the reference signal based on the N precoding vectors. The precoded reference signals transmitted by each of the L transport layers correspond to N ports.

In another possible design, the network device may precode a transmission layer transmission from the reference signal among the L transmission layers based on the N precoding vectors. In other words, the N precoding vectors correspond to a certain transmission layer of the L transmission layers, and the precoded reference signals transmitted on the transmission layer are obtained by precoding the reference signals based on the N precoding vectors. The precoded reference signals transmitted on the transmission layer correspond to the N ports.

Therefore, the network device may use different precoding vectors to precode the reference signals through the reference signals transmitted by each transmission layer. For example, the network device may use N via the reference signal sent by the ith transport layer_lThe reference signals are precoded by (i.e., an example of N) precoding vectors. It should be understood that the reference signals sent by different transmission layers may be precoded by using different precoding vectors, and the number of precoding vectors corresponding to each transmission layer may be different from each other, may also be partially the same, or may also be completely the same. This is not a limitation of the present application.

It should be noted that the reference signal transmitted by the network device through the L transport layers may be a reference signal sent to the same terminal device, or may be a reference signal sent to different terminal devices. This is not a limitation of the present application. However, it can be understood that the precoded reference signal transmitted by the network device through a certain transmission layer, for example, the precoded reference signal transmitted through the ith transmission layer of the L transmission layers, is a reference signal sent to the same terminal device. Wherein, the ith transport layer may be any one of the L transport layers.

In the embodiment of the present application, for convenience of understanding and explanation, it is assumed that a precoded reference signal obtained by precoding a reference signal by a network device based on N precoding vectors is a reference signal sent to the same terminal device. The reference signals sent by the network device to the same terminal device may be transmitted through one or more transport layers. When the reference signal sent by the network device to the same terminal device is transmitted through multiple transmission layers, the precoded reference signal transmitted by each transmission layer may be obtained by precoding the reference signal based on the same N precoding vectors, or obtained by precoding the reference signal based on different precoding vectors on different transmission layers. For convenience of distinction and explanation, it is assumed that the precoded reference signal received by the terminal device on the ith transmission layer is obtained by precoding the reference signal based on the N precoding vectors.

In step 220, the terminal device generates feedback information, which is determined based on the precoding reference signal received by the terminal device.

As described above, the reference signals that can be identified by the terminal device on one transmission layer are the precoded reference signals of N ports, that is, the reference signals corresponding to N precoding vectors. The terminal device may perform channel measurements based on the precoded reference signals for each port to determine the feedback information.

In one possible implementation, the terminal device may generate the feedback information based on a predetermined observation matrix and the received precoding reference signal.

In particular, the terminal device may construct an observation matrix based on the channel matrix. First, the terminal device may estimate a downlink channel. The downlink channel specifically refers to a downlink channel that is not precoded, that is, the downlink channel H described above. The terminal device may estimate the downlink channel according to the reference signal that is not precoded and is sent by the network device, for example. Alternatively, the terminal device may also estimate the downlink channel H according to reciprocity of the uplink and downlink channels. This is not a limitation of the present application.

Singular value decomposition is performed on the downlink channel H to obtain: h ═ U Λ V^H. U is an R-dimensional unitary matrix, V is a T-dimensional unitary matrix, and Lambda is an R-dimensional diagonal matrix. The observation matrix W may be:

when the rank is 1, the rank is set to 1,

[1 0 … 0]is a matrix of one row and R columns, the W can be applied to R ≧ 1;

when the rank is 2, the rank is set to 2,

is a matrix with two rows and two columns, and W can be applied to R ≧ 2;

when the rank is 3, the rank is set to 3,

is a matrix with three rows and R columns, and W can be applied to R ≧ 3;

by analogy, when the rank is L,

for a matrix of L rows and R columns, W may be applied to R ≧ L.

Based on the above list of observation matrices W with different values of rank, the observation matrix W can be represented by the general formula W ═ S (U Λ)^-1And (4) showing. Wherein S is a matrix with Z rows and R columns. Each row in S includes R-1 zero elements, and the z-th element in the z-th row in S is 1. Z represents the rank of the channel matrix. That is, the network device can communicate with the terminal device through Z transport layers at most. Z represents the Z-th transmission layer in the Z transmission layers, Z is more than or equal to 1 and less than or equal to Z, Z is less than or equal to L, and both Z and Z are positive integers.

An equivalent channel Hb can be estimated from a reference signal port corresponding to a certain precoding vector b. The terminal device pre-multiplies the equivalent channel by the observation matrix W, i.e., WHb. The terminal device can obtain L observations.

It is assumed that the network device sends a precoded reference signal to the terminal device through 2 transport layers, i.e., M is 2. Then:

if V is assumed to be [ V ]₁v₂… v_T]Then, then

Wherein the content of the first and second substances,

and

may be referred to as an observation.

Is alpha_b,1The conjugate of (a) to (b),

is alpha_b,2Conjugation of (1). Alpha is alpha_b,1May represent the weight, a, of the precoding vector b fed back for the 1 st transmission layer_b,2The weight of the precoding vector b fed back for the 2 nd transmission layer may be represented.

It can be understood that, when the network device transmits data through a certain transmission layer, the precoding vector for precoding the data may be determined according to the weight of each precoding vector fed back by the terminal device to precode the reference signal. For the convenience of differentiation and explanation, the precoding vector used for precoding data will be referred to as a target precoding vector hereinafter.

For example, for N precoding vectors b₁，b₂，……，b_NThe weights of the feedback are respectively

A target precoding vector for precoding the data may be determined, which may be, for example

Or processing the vector p (e.g., zero forcing,MMSE, SLNR, etc.). In the embodiment of the present application, for convenience of understanding and explanation, a vector obtained by weighting N precoding vectors is used as a target precoding vector. It should be understood that this should not constitute any limitation to the present application. The specific method for processing the weighted sum of the N precoding vectors may refer to the prior art, and the processing procedure is an internal implementation behavior of the network device, which is not limited in this application.

Therefore, the weight of the precoding vector b fed back for the 1 st transmission layer as described above may refer to the weight of the precoding vector b used to generate the target precoding vector when data is transmitted through the 1 st transmission layer; the weight of the precoding vector b fed back for the 2 nd transmission layer may refer to a weight of the precoding vector b used to generate the target precoding vector when data is transmitted through the 2 nd transmission layer.

It can be seen that the observation matrix can convert R received signals corresponding to the same reference signal port on R receive antennas into Z observations, thereby reducing the amount of feedback.

As described above, when the reference signal sent by the network device to the same terminal device is transmitted through multiple transmission layers, the precoded reference signal transmitted by each transmission layer may be obtained by precoding the reference signal based on the same N precoding vectors. Suppose that the N precoding vectors are denoted b₁，b₂，……，b_NThe number of transmission layers is 2. The precoded reference signals generated by the network device through the N precoding vectors can be considered to be available for channel measurement on channels of 2 transmission layers. The terminal device may indicate the weight of each precoding vector in the N precoding vectors in each transmission layer through the feedback information. E.g. by precoding vector b₁The generated precoding reference signal can be obtained through channel measurement: the precoding vector b for the 1 st transmission layer feedback₁Weight of (2)

And the precoding vector b fed back for the 2 nd transmission layer₁Weight of (2)

By precoding vectors b_NThe generated precoding reference signal can be obtained through channel measurement: precoding vector b for 1 st transmission layer feedback_NWeight of (2)

And a precoding vector b fed back for the 2 nd transmission layer_NWeight of (2)

And so on, this is not to be enumerated here.

When the reference signal sent by the network device to the same terminal device is transmitted through multiple transmission layers, the reference signal transmitted by each transmission layer may be obtained by precoding the reference signal based on different precoding vectors. Assuming that the number of transmission layers is 2, N for precoding a reference signal on the 1 st transmission layer₁The precoding vectors can be denoted as

N for precoding reference signals on the 2 nd transmission layer₂The precoding vectors can be denoted as

The terminal device may be based on N received on the 1 st transport layer₁Channel measurement is performed on precoded reference signals of the ports to determine the N₁Weight of precoding vector

The terminal device may also be based on N received on the 2 nd transport layer₂Channel measurement is performed on precoded reference signals of the ports to determine the N₂Weight of precoding vector

Because the precoding vectors corresponding to each transmission layer are different, the terminal device may be based on the observation matrix corresponding to the transmission layer number of 1

The channel of each transport layer is measured separately. The observation value measured by the terminal device based on the precoding reference signal received on the 1 st transmission layer can be used for determining N₁The weight of each precoding vector, and the observed value measured by the terminal equipment based on the precoding reference signal received on the 2 nd transmission layer can be used for determining N₂The weight of each precoding vector.

The terminal device may also perform channel measurement based on the observation matrix corresponding to the transmission layer number greater than 1. The 1 st observation (i.e., the observation corresponding to the 1 st transmission layer) of the plurality of observations (i.e., the observations corresponding to the plurality of transmission layers) measured by the terminal device based on the precoded reference signals received on the 1 st transmission layer may be used to determine N₁Weights of precoding vectors, and a 1 st observation value (i.e., an observation value corresponding to a 1 st transmission layer) of a plurality of observation values (i.e., observation values corresponding to a plurality of transmission layers) measured by the terminal device based on the precoded reference signals received on the 2 nd transmission layer can be used to determine N₂The weight of each precoding vector.

In another possible implementation manner, the terminal device may determine, according to the received signal strength of the precoding reference signal of each port, a ratio of the signal strength of each precoding reference signal to the strength of the precoding reference signal with the maximum strength, so as to generate the feedback information. That is, the feedback information may be used to indicate a ratio of signal strengths of precoded reference signals of a plurality of ports. Since the ratio of the signal strengths of the precoded reference signals of the plurality of ports may reflect to some extent which direction is closer to the direction of the terminal device, the feedback information may be used to indicate the weight of the precoding vector corresponding to each port in the direction close to the terminal device.

It should be understood that the above-listed implementation manners for determining the weight of each precoding vector according to the received precoding reference signal are only examples, and should not limit the present application in any way. The specific implementation manner of the terminal device generating the feedback information according to the received precoding reference signal may also refer to a channel measurement method in the prior art. For the sake of brevity, this is not necessarily an illustration.

Thereafter, the terminal device may generate feedback information based on the determined weight of each precoding vector. As described above, the observation value determined by the terminal device through the observation matrix is the conjugate of the weight of each precoding vector. When generating the feedback information, the terminal device may directly feed back the conjugate of each observation value (i.e., the weight of each precoding vector) to the network device.

Take N precoding vectors for precoding the reference signal as an example. In one implementation, the terminal device may determine, from a plurality of weights corresponding to the N ports, an element with the largest modulus value as a normalization coefficient. The amplitude of the element with the largest modulus value is defined as 1, and the phase is defined as 0. The terminal device may further calculate the relative magnitude and relative phase of the other elements with respect to the normalized coefficient. The terminal device may quantize the relative magnitude and relative phase of the other elements relative to the normalized coefficient to generate feedback information. The feedback information may include, for example, an index of the normalized coefficient and quantized values of the relative magnitude and relative phase of other elements with respect to the normalized coefficient.

It should be understood that the specific method by which the terminal device calculates the relative magnitude and relative phase of the other elements with respect to the normalized coefficients may be many. For example, by means of a difference or an inner product. This is not a limitation of the present application. It should also be understood that the manner described above for generating feedback information for a plurality of weights may be referred to as a normalization manner. The specific method for generating the feedback information by the terminal device through normalizing the direction may refer to the prior art, and a detailed description of a specific process of the terminal device is omitted here for brevity.

It should also be understood that the method for generating the feedback information by the terminal device through the normalization mode is only one possible implementation mode, and should not constitute any limitation to the present application. The terminal device may also quantize the weight of each precoding vector to generate feedback information.

In step 230, the terminal device transmits the feedback information. Accordingly, in step 230, the network device receives the feedback information.

Specifically, the terminal device may carry the feedback information through a PMI in the CSI report, for example. The terminal device may also carry the feedback information through other signaling. The signaling for carrying the feedback information may be an existing signaling or an additional signaling. This is not a limitation of the present application.

The terminal device may send the feedback information to the network device through a physical uplink resource, such as a Physical Uplink Shared Channel (PUSCH) or a Physical Uplink Control Channel (PUCCH), so that the network device determines a target precoding vector for data transmission according to the feedback information.

The specific method for the terminal device to send the first indication information to the network device through the physical uplink resource may be the same as that in the prior art, and a detailed description of a specific process of the terminal device is omitted here for brevity.

The weights of the plurality of precoding vectors fed back by the terminal device may also be used to determine a precoding vector for next generation of the precoded reference signal.

In step 240, the network device determines a precoding vector for generating a precoding reference signal to be transmitted next according to the feedback information.

The following still takes N precoding vectors as an example to describe a specific process of the network device determining a precoding vector for next generation of a precoding reference signal.

For the sake of distinction, the N precoding vectors are denoted as N_kA precoding vector, then the N_kThe precoding vectors are used for k channel measurement, and the precoding vectors are sent by the terminal equipment to indicate the N_kThe feedback information of the weights of the precoding vectors is the feedback information transmitted the kth time. It can be understood that the feedback information sent for the kth time is obtained by performing channel measurement based on the precoding reference signal sent for the kth time by the network device, and the precoding reference signal sent for the kth time may be based on N_kAnd precoding the reference signal by the precoding vector.

In the examples of the present application, this N_kThe weights of the precoding vectors may be used to determine the precoded reference signal transmitted the (k + 1) th time. The precoding vector used to generate the precoded reference signals for the (k + 1) th transmission is N_k+1N is_k+1Is a positive integer.

In one implementation, the network device may be based on this N_kA precoding vector and the N_kThe weight of each precoding vector, N can be determined_k+1One precoding vector of the precoding vectors. The N is_k+1Additional N of precoding vectors_k+1The-1 precoding vectors may be taken from a predetermined set of precoding vectors.

In particular, based on this N_kA precoding vector and the N_kThe weights of the precoding vectors may determine a weighted sum b^(k). The weighted sum b^(k)Can be used as N_k+1One precoding vector of the precoding vectors. It will be appreciated that the weighted sum b^(k)May be the same as the target precoding vector p described above. This is because the target precoding vector p is also weighted by the target precoding vector.

The N is_k+1Additional N of precoding vectors_k+1The-1 precoding vectors may be taken from a predetermined set of precoding vectors. The predetermined precoding vector set may be, for example, a pre-configured precoding vector set, or a precoding vector set updated based on feedback information of the terminal device.

It is understood that when N is_k+1When 1, the network device can directly select N_kThe weighted sum of the precoding vectors determines the precoding vector used to precode the reference signal.

The following describes in detail a specific process of updating the precoding vector set by the network device according to the feedback information sent by the terminal device. For convenience of differentiation and explanation, the updated set of precoding vectors of the network device is referred to as a first set of precoding vectors, and the non-updated set of precoding vectors is referred to as a second set of precoding vectors.

The first set of precoding vectors may be a set of precoding vectors that the network device updates based on the I-th received feedback information. I.e., K ═ I, I ≦ K, and I is a positive integer. The I-th received feedback information is used for indicating N_IWeight of precoding vector, N_IEach precoding vector is used to generate a precoding reference signal for the I-th transmission. The I-th received feedback information may be used to determine a precoding vector used to generate the first set of precoding vectors.

Specifically, the network device may determine N based on the I-th received feedback information_IWeighted sum of precoding vectors

Due to the weighted sum

Is based on a reaction of N_IThe precoding reference signal generated by precoding the reference signal with the precoding vector is obtained by channel measurement, based on the weighted sum

The direction of the signal transmitted by precoding the signal is also infinitely close to the direction of the terminal device. The network device may make a slight perturbation based on this direction, and may derive multiple vectors.

For example, the network device may be based on a weighted sum

And generating T-1 Givens (Givens) rotation matrixes G (m, T, theta) or G (T, m, theta) on the row where the element b with the maximum medium amplitude is positioned. m represents b is

M is a positive integer, and m is more than or equal to 1 and less than or equal to T; t is an integer from 1 to T, T ≠ c, and θ represents a rotation angle. Based on the T-1 Givens rotation matrices G (m, T, theta) or G (T, m, theta), another N of the first set of precoding vectors may be generated_k+11 precoding vector.

The Givens rotation matrix G may be a matrix of T rows and T columns. For matrix G (p, q, θ), let row index p be m, column index q may be traversed from 1 to T, G (m, m, θ) ═ G (q, q, θ) ═ cos θ, -G (m, q, θ) ═ G (q, m, θ) ═ sin θ. The other diagonal elements are 1 and the off-diagonal elements are 0.

Then matrix

Based on the Givens rotation matrix G (m, T, θ), a T × T matrix S can be constructed as follows:

the matrix S comprises T column vectors in total, and each column vector is a T-dimensional vector; theta for sequentially pairing

The two-dimensional vector consisting of the two elements (m, t) is slightly rotated. For example, θ is π/10.

Based on the Givens rotation matrix G (T, m, θ), a T × T matrix S can be constructed as follows:

The two-dimensional vector formed by the two elements (t, m) is slightAnd (4) rotating. For example, θ is π/10.

The quantities in the matrix S constructed from the above-described Givens rotation matrix include the above-described N_IWeighted sum of precoding vectors b^(I) And additional T-1 precoding vectors constructed from the weighted sum. The terminal device may further check whether the T column vectors are linearly related, i.e. whether the matrix S is full rank. If the rank is full, performing Schmidt orthogonalization on the T linearly independent column vectors in the matrix S to obtain a matrix formed by a first precoding vector set

The superscript (1) indicates a matrix formed by a precoding vector set obtained after one update. The matrix composed of the precoding vector set here may be a matrix obtained by arranging column vectors in a predetermined order. The matrix formed by the T-dimensional precoding vectors may be a matrix having a dimension of T × T.

Thus, by updating the second set of precoding vectors, the resulting first set of precoding vectors may comprise at least T precoding vectors. Optionally, the first set of precoding vectors comprises T precoding vectors. Optionally, the first set of precoding vectors comprises o × T precoding vectors, o being an oversampling factor. The o × T precoding vectors can be generated by, for example, interpolating the T equally spaced precoding vectors. The prior art can be referred to for a specific implementation manner of oversampling, which is not limited in this application.

It is to be understood that at least some of the updated first set of precoding vectors and the updated second set of precoding vectors are different.

Further, the above-mentioned N_ISome or all of the precoding vectors may be precoding vectors taken from the second set of precoding vectors.

For example, the N_IThe precoding vectors may all be taken from the second set of precoding vectors. In this case, I may be 1, i.e., the precoded reference signal transmitted the I-th time may be the 1 st timeThe transmitted precoded reference signals. The I-th received feedback information may be the 1 st received feedback information. The second set of precoding vectors may be, for example, a pre-configured set of precoding vectors.

Also for example, the N_IOne of the precoding vectors may be N determined according to the last received feedback information from the terminal device_I-1Weighted sum of precoding vectors, another N_IThe-1 precoding vectors may be taken from the second set of precoding vectors. Wherein N is_I-1Each precoding vector is a precoding vector of a precoding reference signal generated by the network equipment and transmitted in the I-1 st time. In this case, I may be greater than 1. The second set of precoding vectors may be, for example, a pre-configured set of precoding vectors or an updated set of precoding vectors. This is equivalent to repeating the process of updating the set of precoding vectors as described above. After each time of updating the precoding vector set, the updated first precoding vector set is converted into a second precoding vector set when a precoding reference signal is generated next time. After one or more terminal device feedbacks, the network device may update the second set of precoding vectors again.

The above steps 210 to 240 may be repeatedly performed a plurality of times. Therefore, the precoding vector determined by the network equipment and used for precoding the reference signal is closer to the direction of the terminal equipment, so that more accurate feedback of the terminal equipment can be obtained.

In the channel measurement process, the network device may also transmit data with the terminal device at the same time. For example, after the above steps 210 to 240 are repeatedly performed K times, the network device may determine a target precoding vector for data transmission based on the K-th received feedback information.

As an embodiment, the network device may select a precoding vector for precoding the reference signal based on a pre-configured set of precoding vectors (e.g., as an example of an initial set of precoding vectors, i.e., a second set of precoding vectors). E.g. the initial set of precoding vectorsComprising a precoding vector b₁，b₂，……，b_T. The network device may select N precoding vectors from the T precoding vectors to precode the reference signal transmitted for the first time, where N is less than T and both N and T are integers.

For example, the network device selects b from the set of initial precoding vectors₁，b₂，……，b_NThe N precoding vectors precode the reference signals transmitted through the l transmission layer, and the N precoding vectors can be denoted as b_1,l，b_2,l，……，b_N,l. After precoding the reference signal, the network device sends the precoded reference signal through the l-th transmission layer. The network device is based on the N precoding vectors b_1,l，b_2,l，……，b_N,lThe generated precoded reference signal can be regarded as the precoded reference signal transmitted by the network device through the ith transmission layer for the 1 st time.

The terminal equipment carries out channel measurement based on the precoding reference signal received at the l transmission layer and feeds back the weights of the N precoding vectors as

The network device may determine a precoding vector for precoding the reference signal next time based on the weights of the N precoding vectors as

The network device may further select N-1 precoding vectors (assuming for the moment that T-N ≧ N-1) from the remaining T-N precoding vectors in the initial set of precoding vectors, the N-1 precoding vectors denoted, for example, b respectively_N+1，b_N+2，……，b_2N-1. Since the N-1 precoding vectors are used to precode the reference signals transmitted through the l-th transmission layer, they can be denoted as b_N+1,l，b_N+2,l，……，b_2N-1,l. The N-1 precoding vectors and the above

New N precoding vectors may be formed for precoding the reference signals transmitted by the network device through the l-th transmission layer. After precoding the reference signal, the network device sends the precoded reference signal through the l-th transmission layer. The network device is based on the N precoding vectors

b_N+1,l，b_N+2,l，……，b_2N-1,lThe generated precoded reference signal can be regarded as a precoded reference signal transmitted by the network device through the ith transmission layer for the 2 nd time.

By analogy, the network device may repeatedly perform the above operations as long as there are enough precoding vectors in the initial set of precoding vectors. For example, the precoded reference signals transmitted by the network device at the k +1 th time may be based on

And N-1 precoding vectors b of the initial precoding vectors_k(N-1)+2，b_k(N-1)+3，……，b_(k+1)(N-1)+1And precoding the reference signal transmitted by the ith transmission layer.

Since the number of precoding vectors in the initial set of precoding vectors is limited, when the number N 'of the remaining precoding vectors (i.e., precoding vectors that have not been precoded) in the initial set of precoding vectors is less than N-1, the network device may also precode the reference signal transmitted through the l-th transmission layer based on the N' precoding vectors and a vector weighted based on the last received feedback information. The precoded reference signal transmitted this time can be understood as an example of the precoded reference signal transmitted I time described above.

The terminal device may perform channel measurement and send feedback information to indicate the weight of each precoding vector based on the precoding reference signal received on the l-th transmission layer. The feedback information sent by the terminal device at this time may be understood as an example of the feedback information sent at the I-th time described above. After receiving the feedback information from the terminal device, the network device may update the initial precoding vector to obtain an updated set of precoding vectors (i.e., an example of the first set of precoding vectors described above). The specific process of updating the precoding vector set by the network device has been described in detail above, and for brevity, it is not described herein again.

Therefore, based on multiple measurements and feedbacks between the network device and the terminal device, the feedback of the terminal device for the ith transmission layer is closer to the direction of the terminal device, so that the target precoding vector used for precoding data transmitted by the ith transmission layer can be better adapted to the channel.

In one possible design, the matrix formed by the initial set of precoding vectors is a unitary matrix. Let Ψ⁽⁰⁾＝[b₁b₂… b_T]Then, let us⁽⁰⁾Is a unitary matrix. Where the superscript (0) represents the set of non-updated precoding vectors, or, alternatively, the pre-configured set of precoding vectors.

It should be noted that the operation of the network device precoding the reference signal based on the initial set of precoding vectors is not limited to precoding the reference signal transmitted on one transmission layer. When the network device transmits the reference signal through multiple transmission layers, the reference signal transmitted through each transmission layer may be obtained based on different numbers and different precoding vectors. For example, for transmission layers l and z, the network device may first select a plurality of precoding vectors from an initial set of precoding vectors to precode a reference signal transmitted through the l-th transmission layer and a reference signal transmitted through the z-th transmission layer, respectively. The terminal device may perform channel measurement based on the precoding reference signal received on the ith transmission layer and the precoding reference signal received on the zth transmission layer, respectively, and send feedback information to the network device.

For example, the network device may be based on in the initial set of precoding vectors

This N_lReference of precoding vectors to transmission over the l-th transmission layerThe signal is pre-coded, N_lA precoding vector, e.g. denoted b_1,l，

The terminal device performs channel measurement based on the precoding reference signal received on the l-th transmission layer and feeds back the weight of each precoding vector as

Meanwhile, the network equipment can be based on the initial precoding vector in the set

This N_zPrecoding the reference signal transmitted through the z-th transmission layer by the precoding vectors, N_zA precoding vector is e.g. denoted as

Wherein N is_lAnd N_zThe values of (A) may be the same or different. This is not a limitation of the present application.

After receiving the weights of the precoding vectors fed back by the terminal device based on the ith transmission layer and the zth transmission layer, the network device may determine the weighted sum of the precoding vectors determined based on different transmission layers, and precode the reference signals transmitted through the ith transmission layer and the zth transmission layer next time. The specific method for the network device to determine the precoding vector and precode the reference signal based on each transmission layer in the multiple transmission layers is the same as the specific method for determining the precoding vector and precoding the reference signal for the ith transmission layer described above, and for brevity, the detailed description is omitted here.

In addition, the precoding reference signals respectively transmitted by the network device through the l-th transmission layer and the z-th transmission layer may be precoding reference signals sent to the same terminal device, or may be precoding reference signals sent to different terminal devices. This is not a limitation of the present application.

Optionally, the method further comprises: in step 250, the terminal device sends a precoding vector set resetting indication, where the precoding vector set resetting indication is used to indicate that channel measurement is performed based on the reset precoding vector set. Accordingly, in step 260, the network device receives the precoding vector set reset indication.

In some cases, such as when the terminal device is moving rapidly, the channel may change abruptly. At this time, if the channel measurement is still performed based on the precoding vector set determined before, it may not be possible to obtain accurate feedback of the terminal device. The terminal device may determine whether the precoding vector set needs to be reset according to the self movement condition or the difference change condition between the two measurement results. The terminal device may suggest to the network device to update the set of precoding vectors by sending a precoding vector set reset indication to the network device. It should be understood, however, that whether the network device updates the set of precoding vectors does not depend solely on the precoding vector set reset indication sent by the terminal device. The network device may also consider comprehensively whether to update the set of precoding vectors based on further factors.

In step 260, the network device determines a target precoding vector for data transmission according to the kth received feedback information; and precoding the downlink data based on the target precoding vector to obtain precoded data.

In the embodiment of the present application, the target precoding vector for data transmission may be a precoding vector corresponding to a transmission layer. I.e. precoding vectors used to precode data when transmitting data through a certain transmission layer. For example, a precoding vector used to precode data when transmitting data through the l-th transmission layer.

If the network device transmits downlink data through the ith transmission layer, the network device may determine the target precoding vector according to the feedback information received the kth time. Suppose a network device passes N precoding vectors

b_(K-1)(N-1)+2，b_(K-1)(N-1)+3，……，b_K(N-1)+1Precoding the reference signal sent by the Kth transmission layer, wherein the weight of each precoding vector fed back by the terminal equipment at the Kth time is

α_(K-1)(N-1)+2，α_(K-1)(N-1)+3，……，α_K(N-1)+1Then a target precoding vector for precoding data on the l-th transmission layer may be determined

Wherein the content of the first and second substances,

represents a weighted sum of precoding vectors determined based on the last (i.e., K-1) feedback,

indicating what is indicated in the Kth received feedback information

The weight of (c).

It should be understood that the above listed precoding vectors and their weights are only examples and should not limit the present application in any way. It should also be understood that the network device is not limited to transmitting downlink data to the same terminal device through one transport layer. When the network device sends downlink data to the same terminal device through multiple transmission layers, the data transmitted on the corresponding transmission layers can be precoded based on the target precoding vectors corresponding to the transmission layers.

It should also be understood that in the examples of the present application, K.gtoreq.1. The above-listed target precoding vectors show an example of the target precoding vectors determined based on the multiple feedbacks of the terminal device, that is, an example of K > 1. The network device may also determine a target precoding vector for data transmission based on the primary feedback of the terminal device.

For example, if N precoding vectors are used to precode reference signals transmitted through one or more transmission layers, and the N precoding vectors b fed back for the l transmission layer₁，b₂，……，b_NThe weights of the feedback are respectively

A target precoding vector for precoding data on the ith transmission layer may be determined

For another example, if N₁One precoding vector is used to precode reference signals transmitted through one transmission layer (e.g., the 1 st transmission layer, i.e., l ═ 1), and for the N₁A precoding vector

The weights of the feedback are respectively

A target precoding vector for precoding data when transmitting data through the transmission layer may be determined

If N is present₂One precoding vector is used to precode reference signals transmitted through another transmission layer (e.g., the 2 nd transmission layer, i.e., l-2), and the N is₂The weights fed back by the precoding vectors are respectively

This can be achieved if N is passed_lPrecoding the reference signal transmitted on the l transmission layer by the precoding vectors, and aiming at the N_lA precoding vector

The weights of the feedback are respectively

A target precoding vector for precoding data when transmitting data through the l-th transmission layer

Wherein N is_lIs a positive integer.

Optionally, J of the L transport layers are used for transmitting data with the terminal device. The J transport layers may include, for example, the above-described ith transport layer and J-1 transport layers other than the ith transport layer. J is less than or equal to Z and is a positive integer.

That is, the network device may transmit data to the same terminal device through some or all of the L transport layers. For example, if the number of transmission layers used for transmitting data is J, a target precoding vector for precoding data on any one of the J transmission layers may be determined by the method described above.

Optionally, the method further comprises: the network equipment determines the use of the feedback information for transmitting data at the jth transmission layer based on the K times of received feedback informationThe target precoding vector of (1). The J transport layer is any one of J-1 transport layers except the J transport layer. The feedback information received at the K time in the feedback information received at the K time is used for indicating

The weight of each precoding vector. The

The precoding vectors are precoding vectors for precoding reference signals transmitted through the jth transmission layer for the kth time, or precoding vectors for generating precoded reference signals transmitted through the jth transmission layer for the kth time. The

A weighted sum of precoding vectors of

One precoding vector of the precoding vectors. The

The precoding vectors are precoding vectors for precoding reference signals transmitted through the jth transmission layer at the (k + 1) th time, or generating precoding vectors for precoding reference signals transmitted through the jth transmission layer at the (k + 1) th time. Wherein J is more than or equal to 1 and less than or equal to J-1, and J can be randomly selected from 1 to J-1.

That is, when the network device sends the precoding reference signal to the same terminal device through multiple transmission layers, the terminal device may feed back the weight of each precoding vector corresponding to the precoding reference signal transmitted through each transmission layer through the same feedback information. Only the precoding vectors corresponding to the precoding reference signals transmitted through different transmission layers may be different, and the number of the corresponding precoding vectors may also be different. For ease of distinction, different ones of the M transport layers are distinguished above by superscripts (j) and (l).

It should be noted that the number of transmission layers measured in the channel measurement of the network device is not equal to the number of transmission layers used for data transmission. The network device may schedule some or all of the transmission layers for transmitting data according to the number of transmission layers determined by the channel measurement.

Since the target precoding vector is a precoding vector corresponding to one transmission layer. The target precoding vector may be used to precode data for transmission over the transmission layer. When the network device transmits data through a plurality of transmission layers, the network device may determine target precoding vectors respectively corresponding to the plurality of transmission layers, and the network device may precode the data transmitted through the transmission layers based on the precoding vectors corresponding to the transmission layers, thereby obtaining precoded data. Or, the network device may also determine a precoding matrix according to the target precoding vectors respectively corresponding to the multiple transmission layers, so as to precode the data to be transmitted, thereby obtaining precoded data.

For example, the network device may precode the reference signal of each transmission layer individually based on different precoding vectors, and the terminal device may also perform channel measurement individually based on the precoded reference signals received on different transmission layers, thereby determining the weight of each precoding vector corresponding to each transmission layer. The network device may also determine a target precoding vector corresponding to each transmission layer based on the weight of each precoding vector fed back by the terminal device for each transmission layer. Such as p as shown above⁽¹⁾And p⁽²⁾。

For another example, the network device may precode the reference signal based on a plurality of precoding vectors, and the terminal device may also perform channel measurement based on the received precoded reference signal, thereby determining the weight of each precoding vector. As described above, the terminal device may determine the number of transmission layers from the channel matrix, and then determine the observation value based on the observation matrix corresponding to the number of transmission layers, thereby determining the weight of each precoding vector at different transmission layers. The network device can determine the precoding vectors fed back by the terminal device for each transmission layer based on the weight of each precoding vectorTarget precoding vectors corresponding to each transmission layer, e.g. p as indicated above_l. The network device may also construct a precoding matrix based on the weight of each precoding vector fed back by the terminal device for each transmission layer, e.g., p₁To p_LAnd constructing a precoding matrix.

The specific way for the network device to determine the target precoding vector based on the feedback information sent by the terminal device is not limited to the above. The present application does not limit the specific manner in which the network device determines the target precoding vector.

In step 270, the network device transmits the precoded data. Correspondingly, in step 270, the terminal device receives the precoded data.

It should be understood that the specific process of the network device transmitting the precoded data through the physical downlink resource, such as a Physical Downlink Shared Channel (PDSCH), may be the same as that in the prior art. For brevity, no further description is provided herein.

It should also be understood that the specific process of the channel measurement method 200 provided herein is described in detail above in conjunction with fig. 2. This should not be construed as limiting the application in any way. Fig. 2 is an example only, and shows a flow of transmitting downlink data after repeating the operations of steps 210 to 240K times. However, it should be understood that K times is only an example and should not limit the present application in any way. The present application does not limit the timing when the network device sends the downlink data. In other words, the present application does not limit the execution sequence of steps 210 to 240 and 260 to 270.

Based on the above technical solution, the terminal device may perform channel measurement and feedback based on the precoding reference signal that is sent by the network device for multiple times. The precoding vector used by the precoding reference signal sent by the network device each time refers to the information fed back by the terminal device at the previous time, so that the precoding vector can be closer to the direction of the terminal device, and the obtained feedback of the terminal device is more accurate. In addition, the network device may determine a precoding vector used for precoding data based on the last feedback of the terminal device, and thus the determined precoding vector may be considered as a precoding vector closest to the terminal device direction in the currently obtained channel measurement result, which is beneficial to improving data transmission performance.

The method provided by the embodiment of the present application is described in detail above with reference to fig. 2. Hereinafter, the apparatus provided in the embodiment of the present application will be described in detail with reference to fig. 3 to 5.

Fig. 3 is a schematic block diagram of a communication device provided in an embodiment of the present application. As shown in fig. 3, the communication device 1000 may include a processing unit 1100 and a transceiving unit 1200.

In one possible design, the communication apparatus 1000 may correspond to the terminal device in the above method embodiment, and may be, for example, the terminal device or a chip configured in the terminal device.

Specifically, the communication apparatus 1000 may correspond to the terminal device in the method 200 according to the embodiment of the present application, and the communication apparatus 1000 may include a unit for executing the method executed by the terminal device in the method 200 in fig. 2. Also, the units in the communication device 1000 and the other operations and/or functions described above are respectively for implementing the corresponding flows of the method 200 in fig. 2.

When the communication device 1000 is used to execute the method 200 in fig. 2, the processing unit 1100 may be configured to execute step 220 in the method 200, and the transceiver unit 1200 may be configured to execute step 210, step 230, step 250, and step 270 in the method 200. It should be understood that the specific processes of the units for executing the corresponding steps are already described in detail in the above method embodiments, and therefore, for brevity, detailed descriptions thereof are omitted.

It is further understood that when the communication apparatus 1000 is a terminal device, the transceiver unit 1200 in the communication apparatus 1000 may correspond to the transceiver 2020 in the terminal device 2000 shown in fig. 4, and the processing unit 1100 in the communication apparatus 1000 may correspond to the processor 2010 in the terminal device 2000 shown in fig. 4.

It should also be understood that when the communication device 1000 is a chip configured in a terminal device, the transceiver unit 1200 in the communication device 1000 may be an input/output interface.

In another possible design, the communication apparatus 1000 may correspond to the network device in the above method embodiment, and may be, for example, a network device or a chip configured in a network device.

Specifically, the communication apparatus 1000 may correspond to the network device in the method 200 according to the embodiment of the present application, and the communication apparatus 1000 may include a unit for performing the method performed by the network device in the method 200 in fig. 2. Also, the units in the communication device 1000 and the other operations and/or functions described above are respectively for implementing the corresponding flows of the method 200 in fig. 2.

When the communication device 1000 is used to execute the method 200 in fig. 4, the processing unit 1100 may be configured to execute the steps 240 and 260 in the method 200, and the transceiver unit 1200 may be configured to execute the steps 210, 230, 250, and 270 in the method 200. It should be understood that the specific processes of the units for executing the corresponding steps are already described in detail in the above method embodiments, and therefore, for brevity, detailed descriptions thereof are omitted.

It should also be understood that when the communication apparatus 1000 is a network device, the transceiving unit in the communication apparatus 1000 may correspond to the transceiver 3200 in the network device 3000 shown in fig. 5, and the processing unit 1100 in the communication apparatus 1000 may correspond to the processor 3100 in the network device 3000 shown in fig. 5.

It should also be understood that when the communication device 1000 is a chip configured in a network device, the transceiver unit 1200 in the communication device 1000 may be an input/output interface.

Fig. 4 is a schematic structural diagram of a terminal device 2000 according to an embodiment of the present application. The terminal device 2000 can be applied to the system shown in fig. 1, and performs the functions of the terminal device in the above method embodiment. As shown, the terminal device 2000 includes a processor 2010 and a transceiver 2020. Optionally, the terminal device 2000 further comprises a memory 2030. The processor 2010, the transceiver 2002 and the memory 2030 may be in communication with each other via the interconnection path to transfer control and/or data signals, the memory 2030 may be used for storing a computer program, and the processor 2010 may be used for retrieving and executing the computer program from the memory 2030 to control the transceiver 2020 to transmit and receive signals. Optionally, the terminal device 2000 may further include an antenna 2040, configured to transmit uplink data or uplink control signaling output by the transceiver 2020 by using a wireless signal.

The processor 2010 and the memory 2030 may be combined into a processing device, and the processor 2010 is configured to execute the program codes stored in the memory 2030 to achieve the above functions. In particular, the memory 2030 may be integrated with the processor 2010 or may be separate from the processor 2010. The processor 2010 may correspond to the processing unit in fig. 3.

The transceiver 2020 may correspond to the transceiver unit in fig. 3, and may also be referred to as a transceiver unit. The transceiver 2020 may include a receiver (or receiver, receiving circuit) and a transmitter (or transmitter, transmitting circuit). Wherein the receiver is used for receiving signals, and the transmitter is used for transmitting signals.

It should be understood that terminal device 2000 shown in fig. 4 is capable of implementing various processes involving the terminal device in the method embodiment shown in fig. 2. The operations and/or functions of the modules in the terminal device 2000 are respectively to implement the corresponding flows in the above-described method embodiments. Reference may be made specifically to the description of the above method embodiments, and a detailed description is appropriately omitted herein to avoid redundancy.

The processor 2010 may be configured to perform the actions described in the preceding method embodiments that are implemented within the terminal device, and the transceiver 2020 may be configured to perform the actions described in the preceding method embodiments that the terminal device transmits to or receives from the network device. Please refer to the description of the previous embodiment of the method, which is not repeated herein.

Optionally, the terminal device 2000 may further include a power supply 2050 for supplying power to various devices or circuits in the terminal device.

In addition, in order to further improve the functions of the terminal device, the terminal device 2000 may further include one or more of an input unit 2060, a display unit 2070, an audio circuit 2080, a camera 2090, a sensor 2100, and the like, and the audio circuit may further include a speaker 2082, a microphone 2084, and the like.

Fig. 5 is a schematic structural diagram of a network device provided in the embodiment of the present application, which may be a schematic structural diagram of a base station, for example. The base station 3000 can be applied to the system shown in fig. 1, and performs the functions of the network device in the above method embodiment. As shown, the base station 3000 may include one or more radio frequency units, such as a Remote Radio Unit (RRU) 3100 and one or more baseband units (BBUs) (which may also be referred to as Distributed Units (DUs)) 3200. The RRU 3100 may be referred to as a transceiver unit and corresponds to the transceiver unit 1100 in fig. 3. Alternatively, the transceiving unit 3100 may also be referred to as a transceiver, transceiving circuit, or transceiver, etc., which may comprise at least one antenna 3101 and a radio frequency unit 3102. Alternatively, the transceiving unit 3100 may include a receiving unit and a transmitting unit, the receiving unit may correspond to a receiver (or receiver, receiving circuit), and the transmitting unit may correspond to a transmitter (or transmitter, transmitting circuit). The RRU 3100 part is mainly used for transceiving and converting radio frequency signals to baseband signals, for example, for sending indication information to a terminal device. The BBU 3200 section is mainly used for performing baseband processing, controlling a base station, and the like. The RRU 3100 and the BBU 3200 may be physically disposed together or may be physically disposed separately, i.e. distributed base stations.

The BBU 3200 is a control center of the base station, and may also be referred to as a processing unit, and may correspond to the processing unit 1200 in fig. 3, and is mainly used for completing baseband processing functions, such as channel coding, multiplexing, modulating, spreading, and the like. For example, the BBU (processing unit) may be configured to control the base station to perform an operation procedure related to the network device in the foregoing method embodiment, for example, to generate the foregoing indication information.

In an example, the BBU 3200 may be formed by one or more boards, and the boards may collectively support a radio access network of a single access system (e.g., an LTE network), or may respectively support radio access networks of different access systems (e.g., an LTE network, a 5G network, or other networks). The BBU 3200 also includes a memory 3201 and a processor 3202. The memory 3201 is used to store necessary instructions and data. The processor 3202 is used for controlling the base station to perform necessary actions, for example, for controlling the base station to execute the operation flow related to the network device in the above method embodiment. The memory 3201 and processor 3202 may serve one or more boards. That is, the memory and processor may be provided separately on each board. Multiple boards may share the same memory and processor. In addition, each single board can be provided with necessary circuits.

It should be appreciated that the base station 3000 shown in fig. 5 is capable of implementing various processes involving network devices in the method embodiment shown in fig. 2. The operations and/or functions of the respective modules in the base station 3000 are respectively for implementing the corresponding flows in the above-described method embodiments. Reference may be made specifically to the description of the above method embodiments, and a detailed description is appropriately omitted herein to avoid redundancy.

BBU 3200 as described above can be used to perform actions described in previous method embodiments as being implemented internally by a network device, while RRU 3100 can be used to perform actions described in previous method embodiments as being sent by or received from a terminal device by a network device. Please refer to the description of the previous embodiment of the method, which is not repeated herein.

It should be understood that the base station 3000 shown in fig. 5 is only one possible architecture of a network device, and should not constitute any limitation to the present application. The method provided by the application can be applied to network equipment with other architectures. E.g. network equipment comprising CUs, DUs and Active Antenna Units (AAUs), etc. The present application is not limited to the specific architecture of the network device.

The embodiment of the application also provides a processing device, which comprises a processor and an interface; the processor is configured to perform the method of any of the above method embodiments.

It is to be understood that the processing means described above may be one or more chips. For example, the processing device may be a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a system on chip (SoC), a Central Processing Unit (CPU), a Network Processor (NP), a digital signal processing circuit (DSP), a Microcontroller (MCU), a programmable logic controller (PLD), or other integrated chips.

In implementation, the steps of the above method may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The steps of a method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in a 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 a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor. To avoid repetition, it is not described in detail here.

It should be noted that the processor in the embodiments of the present application may be an integrated circuit chip having signal processing capability. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor described above may be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding 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 a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

It will be appreciated that the memory in the embodiments of the subject application can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. The non-volatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM, enhanced SDRAM, SLDRAM, Synchronous Link DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

According to the method provided by the embodiment of the present application, the present application further provides a computer program product, which includes: computer program code which, when run on a computer, causes the computer to perform the method in the embodiment shown in fig. 2.

According to the method provided by the embodiment of the present application, the present application also provides a computer readable medium storing program code, which when run on a computer, causes the computer to execute the method in the embodiment shown in fig. 2.

According to the method provided by the embodiment of the present application, the present application further provides a system, which includes the foregoing one or more terminal devices and one or more network devices.

The network device in the foregoing device embodiments completely corresponds to the terminal device and the network device or the terminal device in the method embodiments, and the corresponding module or unit executes the corresponding steps, for example, the communication unit (transceiver) executes the steps of receiving or transmitting in the method embodiments, and other steps besides transmitting and receiving may be executed by the processing unit (processor). The functions of the specific elements may be referred to in the respective method embodiments. The number of the processors may be one or more.

As used in this specification, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between 2 or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from two components interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Those of ordinary skill in the art will appreciate that the various illustrative logical blocks and steps (step) described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

In the above embodiments, the functions of the functional units may be fully or partially implemented by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions (programs). The procedures or functions described in accordance with the embodiments of the present application are generated in whole or in part when the computer program instructions (programs) are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a Digital Video Disk (DVD)), or a semiconductor medium (e.g., a Solid State Disk (SSD)), among others.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of channel measurement, comprising:

determining a target precoding vector for data transmission based on the K times of received feedback information; the K times of received feedback information are determined based on K times of transmitted precoding reference signals, wherein the K-th time of received feedback information is used for indicating N_kWeight of precoding vectors, N_kThe weighted sum of precoding vectors is N_k+1One of the precoding vectors; said N is_kEach precoding vector is used for generating a precoding reference signal sent at the kth time, and N is_k+1The precoding vectors are used for generating precoding reference signals sent for the (k + 1) th time; k is more than or equal to 1, K is more than or equal to 1 and less than or equal to K, and K, K and N_kAnd N_k+1Are all positive integers;

pre-coding data to be transmitted according to the target pre-coding vector to obtain pre-coded data;

and transmitting the pre-coded data.

2. The method of claim 1, wherein said N is_k+1The remaining N of the precoding vectors_k+1-1 precoding vector is a precoding vector of a predetermined set of precoding vectors.

3. The method of claim 1, wherein the method further comprises:

generating a first precoding vector set based on the I-th received feedback information in the K received feedback information, wherein the I-th received feedback information is used for indicating N_IWeight of precoding vectors, N_IThe precoding vectors are used for generating precoding reference signals sent for the I time; the first set of precoding vectors comprisesSaid N is_IWeighted sum of precoding vectors and their weight determination

And based on

4. The method of claim 3, wherein the precoding vector used to generate the precoded reference signal for the I +1 th transmission is a precoding vector in the first set of precoding vectors; at least part of precoding vectors used for generating the precoding reference signals of the previous I times of transmission are vectors in a second predetermined precoding vector set; the second set of precoding vectors is different from the first set of precoding vectors.

5. The method of claim 3 or 4, wherein the first set of precoding vectors comprises at least T precoding vectors; and

generating a first precoding vector set based on the ith received feedback information in the K received feedback information, including:

determining the N based on the I-th received feedback information in the K received feedback information_IWeighted sum of precoding vectors

A precoding vector in the first set of precoding vectors;

based on

C is a positive integer, and c is more than or equal to 1 and less than or equal to T; t is an integer value from 1 to T, T is not equal to c, and theta represents a rotation angle;

generating remaining T-1 vectors of the first set of precoding vectors based on the T-1 Givens rotation matrices G (c, T, θ) or G (T, c, θ).

6. The method according to any of claims 1 to 5, wherein the K times received feedback information is used to determine a precoding vector used for transmitting the data through the L-th transmission layer of the L transmission layers; one or more transmission layers in the L transmission layers are used for transmitting the data, L is more than or equal to 1 and less than or equal to L, L is more than or equal to 1, and L and L are integers.

7. The method of claim 6, wherein J transport layers of the L transport layers are used for transmitting data, the J transport layers including the L-th transport layer and J-1 transport layers other than the L-th transport layer, J ≦ 2 ≦ L, J being an integer;

the method further comprises the following steps:

determining a precoding vector used for transmitting data on an mth transmission layer based on the feedback information received K times, wherein the jth transmission layer is any one of the J-1 transmission layers; the feedback information received for the K times is determined by precoding reference signals sent on the jth transmission layer for the K times; the feedback information received at the K time in the feedback information received at the K time is used for indicating

A weight of a precoding vector, the

A weighted sum of precoding vectors of

One of the precoding vectors; the above-mentioned

8. The method of any of claims 1 to 7, further comprising:

receiving a precoding vector set reset indication which is used for indicating that channel measurement is carried out based on the reset precoding vector set.

9. A method of channel measurement, comprising:

generating feedback information based on the received precoding reference signal, the feedback information indicating weights of one or more precoding vectors, the one or more precoding vectors being precoding vectors used to generate the precoding reference signal;

and sending the feedback information, wherein the feedback information is used for determining precoding vectors used for data transmission on each transmission layer.

10. The method of claim 9, wherein the generating feedback information based on the received precoded reference signal comprises:

determining weights of the one or more precoding vectors based on a predetermined observation matrix W and the received precoding reference signals; wherein, W is S (U Λ)^-1(ii) a U and Λ are matrixes obtained by singular value decomposition of a channel matrix H; u is R-dimensional unitary matrix, ΛIs an R-dimension diagonal matrix; s is a matrix of Z rows and R columns, each row in S comprises R-1 zero elements, and the Z-th element in the Z-th row in S is 1; z is more than or equal to 1 and less than or equal to Z, Z represents the rank of a channel matrix H, R represents the number of receiving antennas, and Z, Z, T and R are integers;

generating the feedback information based on weights of the one or more precoding vectors.

11. The method of claim 9 or 10, wherein the method further comprises:

12. A communications apparatus, comprising:

a processing unit, configured to determine a target precoding vector for data transmission based on the K times of received feedback information; the K times of received feedback information are determined based on K times of transmitted precoding reference signals, wherein the K-th time of received feedback information is used for indicating N_kWeight of precoding vectors, N_kThe weighted sum of precoding vectors is N_k+1One of the precoding vectors; said N is_kEach precoding vector is used for generating a precoding reference signal sent at the kth time, and N is_k+1The precoding vectors are used for generating precoding reference signals sent for the (k + 1) th time; k is more than or equal to 1, K is more than or equal to 1 and less than or equal to K, and K, K and N_kAnd N_k+1Are all positive integers; the processing unit is further configured to precode data to be transmitted according to the target precoding vector to obtain precoded data;

and the receiving and sending unit is used for sending the precoded data.

13. The apparatus of claim 12, wherein N is the number of bits in the set of bits_k+1The remaining N of the precoding vectors_k+1-1 precoding vector is a predetermined set of precoding vectorsThe precoding vectors in the sum.

14. The apparatus of claim 12, wherein the processing unit is further for generating a first set of precoding vectors based on an I-th received feedback information of the K received feedback information, the I-th received feedback information indicating N_IWeight of precoding vectors, N_IThe precoding vectors are used for generating precoding reference signals sent for the I time; the first set of precoding vectors comprises N_IWeighted sum of precoding vectors and their weight determination

And based on

15. The apparatus of claim 14, wherein a precoding vector used to generate the I +1 th transmitted precoded reference signal is a precoding vector in the first set of precoding vectors; at least part of precoding vectors used for generating the precoding reference signals of the previous I times of transmission are vectors in a second predetermined precoding vector set; the second set of precoding vectors is different from the first set of precoding vectors.

16. The apparatus of claim 14 or 15, wherein the first set of precoding vectors comprises at least T precoding vectors,

the processing unit is specifically configured to:

A precoding vector in the first set of precoding vectors;

based on

17. The apparatus according to any of claims 12 to 16, wherein the K times received feedback information is used to determine a precoding vector used for transmitting the data through the ith transmission layer of L transmission layers; one or more transmission layers in the L transmission layers are used for transmitting the data, L is more than or equal to 1 and less than or equal to L, L is more than or equal to 1, and L and L are integers.

18. The apparatus of claim 17, wherein J transport layers of the L transport layers are used for transmitting data, the J transport layers including the L-th transport layer and J-1 transport layers other than the L-th transport layer, J ≦ 2 ≦ L, J being an integer;

the method further comprises the following steps:

A weight of a precoding vector, the

A weighted sum of precoding vectors of

One of the precoding vectors; the above-mentioned

19. The apparatus of any one of claims 12 to 18, wherein the transceiver unit is further to receive a reset indication from a set of precoding vectors, the set of precoding vectors reset indication to indicate that channel measurements are to be made based on the reset set of precoding vectors.

20. A communications apparatus, comprising:

a processing unit, configured to generate feedback information based on the received precoding reference signal, where the feedback information is used to indicate weights of one or more precoding vectors, and the one or more precoding vectors are precoding vectors used to generate the precoding reference signal;

and the receiving and sending unit is used for sending the feedback information, and the feedback information is used for determining precoding vectors used for data transmission on each transmission layer.

21. The apparatus as recited in claim 20, said processing unit to:

determining weights of the one or more precoding vectors based on a predetermined observation matrix W and the received precoding reference signals; wherein, W is S (U Λ)^-1(ii) a U and Λ are matrixes obtained by singular value decomposition of a channel matrix H; u is an R-dimensional unitary matrix, and Lambda is an R-dimensional diagonal matrix; s is a matrix of Z rows and R columns, each row in S comprises R-1 zero elements, and the Z-th element in the Z-th row in S is 1; z is more than or equal to 1 and less than or equal to Z, Z represents the rank of the channel moment H, R represents the number of receiving antennas, and Z, Z, T and R are integers;

22. The apparatus of claim 20 or 21, wherein the transceiver unit is further configured to send a precoding vector set reset indication, the precoding vector set reset indication indicating that channel measurements are to be performed based on the reset precoding vector set.

23. A communications apparatus comprising at least one processor configured to perform the method of any of claims 1-11.

24. A computer-readable medium, comprising a computer program which, when run on a computer, causes the computer to perform the method of any one of claims 1 to 11.