CN107113661B

CN107113661B - Precoding Matrix Indicator (PMI) feedback method and device

Info

Publication number: CN107113661B
Application number: CN201480084493.XA
Authority: CN
Inventors: 吴强; 张雷鸣; 刘建琴; 刘江华
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-12-31
Filing date: 2014-12-31
Publication date: 2020-07-07
Anticipated expiration: 2034-12-31
Also published as: WO2016106710A1; CN107113661A

Abstract

By the PMI feedback method described in this embodiment, in different scenarios, the PMIs in some items among different subcarriers are the same, and the PMIs corresponding to the respective PMIs of the different subcarriers are integrated, so that the UE only feeds back a common PMI once in a process of determining a precoding matrix, and the common PMI is used for indicating the precoding matrices of the different subcarriers, so that the base station determines the precoding matrices of the respective subcarriers respectively through the common PMI and the non-common PMIs (in this embodiment, the first PMI and the second PMI) under the different subcarriers. And the UE sends PMIs which can be used by all subcarriers in a public way and non-public PMIs which cannot be used in the public way to the base station, wherein in the process of determining the precoding matrixes of the two subcarriers once, the total number of the fed-back PMIs is K, the PMIs are used for indicating Q precoding matrixes under the two subcarriers, and the number K of the fed-back PMIs is less than the number of Q, so that the aim of saving channel resources is fulfilled.

Description

Precoding Matrix Indicator (PMI) feedback method and device

Background

The Long Term Evolution (LTE) technology is a Long Term Evolution of Universal Mobile Telecommunications System (UMTS) technology standard organized by The 3rd generation Partnership Project (3 GPP), and The LTE System introduces multiple-Input and multiple-Output (MIMO) key transmission technologies, which significantly increases spectral efficiency and data transmission rate.

Through the transmission precoding technique and the reception combining technique, the MIMO-based wireless communication system can obtain diversity and array gain. The MIMO-based wireless communication system needs to perform precoding processing on signals, and a signal transmission function based on precoding can be expressed as:

where y is the received signal vector, H is the channel matrix,

is a pre-coding matrix, s is a transmitting signal vector, n is a measuring noise, the transmitting signal vector s passes through the pre-coding matrix at the transmitting end

Precoding to obtain a precoded matrix

H is the channel characteristics matrix, reflecting the characteristics of the current channel,

right-multiplying by the channel matrix H to obtain

It can be shown that in the absence of noise, the received signal vector y received at the receiving end can be determined by superimposing the signals of the channel numbers after passing through the air interface and the measured noise n.

Achieving optimal precoding typically requires the transmitter to obtain Channel State Information (CSI) in advance. The transmitter and receiver may be a base station device or a terminal device, respectively. In the downlink data transmission process, the transmitter may be a base station device, and the receiver may be a terminal device. A common approach is for the terminal device to quantize and report the instantaneous CSI to the base station.

The CSI information reported by the terminal device includes Rank Indicator (RI), Precoding Matrix Indicator (PMI), Channel Quality Indicator (CQI), and the like, where the RI may be used to indicate the number of transmission layers and the Precoding Matrix used for data transmission

PMI may be used to indicate a precoding matrix used for data transmission

In a multi-carrier system, signals can be transmitted on carriers of different frequency bands, and since different carriers correspond to different precoding matrices, a terminal needs to report PMI information under different carriers. In some cases, each carrier may contain multiple PMIs that collectively indicate a precoding matrix used in transmitting signals using that carrier. For example, signals are transmitted on carrier 1 and carrier 2, the precoding matrix corresponding to carrier 1 is W1, and the precoding matrix corresponding to carrier 2 is W2; wherein PMI1 and PMI2 collectively indicate the W1, and PMI3 and PMI4 collectively indicate the W2. In this case, the UE is required to report the PMI1, PMI2, PMI3 and PMI4, however, in the wireless transmission process, the resources are very limited, and such a transmission method makes the number of PMIs feedbacked large, wasting the resources of the air interface.

In addition, in some scenarios, the problem of air interface resource waste is more serious.

For example, in some scenarios of 3D MIMO (3 Dimension MIMO), under one carrier, PMIs of 2 precoding matrices need to be fed back, indicating a vertical precoding matrix and a horizontal precoding matrix, respectively. The vertical direction and horizontal direction represent precoding matrices by a Kronecker Product (Kronecker Product) of a vertical direction precoding matrix and a horizontal direction precoding matrix. Precoding matrix V₁Can be represented as follows:

wherein the content of the first and second substances,

representing the Kronecker Product. Matrix V₁The size of (A) is determined by the number of rows and columns of the vertical precoding matrix A and the number of rows and columns of the horizontal precoding matrix B. Here, a may also be a horizontal precoding matrix, and correspondingly, B is a vertical precoding matrix.

In addition, in some other scenarios, the precoding matrix V in the codebook for each carrier₂Can be expressed as a dual codebook structure, a long-term wideband characteristic matrix W₁The long-term/broadband characteristic of the channel is embodied; short term narrow band characteristic W₂Embodying the short-term/sub-band characteristics of the channel. In the feedback of PMI, W₁And W₂Respectively indicated by different PMIs. Precoding matrix V₂Can be expressed as follows:

V₂＝W₁×W₂

in the prior art, a base station responds to PMIs (or W) corresponding to A and B fed back by UE₁，W₂Corresponding PMI) determines a precoding matrix V₁(or precoding matrix V)₂). As described above, different carriers correspond to different precoding matrices. For each carrier, the number of fed-back PMIs is the number of the above precoding matrices, e.g. to determine the precoding matrix of carrier 1

Need to feed back PMI of A and PMI of B, in order to determine precoding matrix of carrier 2

The PMI of C and the PMI of D need to be fed back, so that the number of the PMIs fed back is greatly increased, and the resources of an air interface are wasted.

Disclosure of Invention

The invention provides a data transmission method, which is used for avoiding waste of air interface resources while realizing PMI feedback.

In a first aspect, an embodiment of the present invention provides a feedback method for precoding matrix indicator PMI, which is used in a wireless communication system with multi-carrier capability, where a user equipment UE in the wireless communication system uses a first subcarrier and a second subcarrier to communicate with a network side device, and the method includes: the UE determines at least one common PMI, at least one first PMI and at least one second PMI, wherein the at least one common PMI and the at least one first PMI are used for indicating a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the UE transmits the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system.

In a first possible implementation manner of the first aspect, the precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner,

the vertical precoding matrix of the first subcarrier indicated by the common PMI is:

wherein N is a positive integer, k is an integer greater than or equal to 0 and less than or equal to N-1; m is the length of the precoding matrix W corresponding to the common PMI, and T represents the transpose of the matrix.

In a third possible implementation manner of the first aspect, the precoding matrix of the first subcarrier is a product of a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier; the precoding matrix of the second subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the second subcarrier; the common PMI is used for indicating a long-term wideband characteristic matrix of the first subcarrier; the common PMI is further used for indicating a long-term wideband characteristic matrix of the second subcarrier; the first PMI is used for indicating a short-term narrowband characteristic matrix of the first subcarrier; the second PMI is used for indicating a short-term narrowband characteristic matrix of the second subcarrier.

With reference to the first aspect, or any one of the first to third possible implementation manners of the first aspect, in a fourth possible implementation manner, the method further includes: the UE determines and sends a first PMI compensation value delta, wherein the delta is used for indicating a precoding matrix of the first subcarrier together with the at least one common PMI and the at least one first PMI.

With reference to the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner, the method is characterized in that: the UE determines a first PMI compensation value δ, including: and determining the first PMI compensation value delta according to the second subcarrier precoding matrix and the first subcarrier precoding matrix.

With reference to any one of the fourth possible implementation manner and the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner, the sending, by the UE, the first PMI compensation value δ specifically includes: and transmitting the first PMI compensation value delta through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).

In a second aspect, an embodiment of the present invention provides a feedback method for precoding matrix indicator PMI, which is used in a wireless communication system with multi-carrier capability, where a base station in the wireless communication system communicates with a user equipment UE using a first subcarrier and a second subcarrier, and the method includes: the base station receives at least one common PMI, at least one first PMI and at least one second PMI, wherein the at least one common PMI and the at least one first PMI are used for indicating a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the base station determines a precoding matrix of the first subcarrier according to the at least one common PMI and the at least one first PMI, and determines a precoding matrix of a second subcarrier according to the at least one common PMI and the second PMI.

In a first possible implementation manner of the second aspect, the precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner, the method includes: the vertical precoding matrix of the first subcarrier indicated by the common PMI is:

In a third possible implementation manner of the second aspect, the precoding matrix of the first subcarrier is a product of a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier; the precoding matrix of the second subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the second subcarrier; the common PMI is used for indicating a long-term wideband characteristic matrix of the first subcarrier; the common PMI is further used for indicating a long-term wideband characteristic matrix of the second subcarrier; the first PMI is used for indicating a short-term narrowband characteristic matrix of the first subcarrier; the second PMI is used for indicating a short-term narrowband characteristic matrix of the second subcarrier.

With reference to the second aspect, or any one of the first to third possible implementation manners of the second aspect, in a fourth possible implementation manner, the method further includes: the base station receives a first PMI compensation value delta sent by the UE, and the base station determines a precoding matrix of the first subcarrier according to the delta, the at least one common PMI and the at least one first PMI.

With reference to the fourth possible implementation manner of the second aspect, in a fifth possible implementation manner, the receiving, by the base station, the first PMI compensation value δ specifically includes: and the base station receives the first PMI compensation value delta through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).

In a third aspect, an embodiment of the present invention provides a precoding matrix indicator PMI feedback apparatus, used in a wireless communication system with multi-carrier capability, where a user equipment UE in the wireless communication system communicates with a network side device using a first subcarrier and a second subcarrier, and the UE includes: a determining unit, configured to determine at least one common PMI, at least one first PMI and at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; a transmitting unit configured to transmit the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system.

In a first possible implementation manner of the third aspect, the method includes: the precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier;

the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner, the method includes:

In a third possible implementation manner of the third aspect, the method includes: the precoding matrix of the first subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier; the precoding matrix of the second subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the second subcarrier; the common PMI is used for indicating a long-term wideband characteristic matrix of the first subcarrier; the common PMI is further used for indicating a long-term wideband characteristic matrix of the second subcarrier; the first PMI is used for indicating a short-term narrowband characteristic matrix of the first subcarrier; the second PMI is used for indicating a short-term narrowband characteristic matrix of the second subcarrier.

With reference to the third aspect, or any one of the first to third possible implementation manners of the third aspect, in a fourth possible implementation manner, the method includes: the determining unit is further configured to determine a first PMI compensation value δ, where δ is used to determine a precoding matrix of the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; the transmitting unit is further configured to transmit the first PMI compensation value δ.

With reference to the fourth possible implementation manner of the third aspect, in a fifth possible implementation manner, the determining unit is further configured to determine the first subcarrier precoding matrix and the second subcarrier precoding matrix; the determining unit determines the at least one common PMI according to the first subcarrier precoding matrix; the determining unit determines a first PMI compensation value δ, including: and determining the first PMI compensation value delta according to the second subcarrier precoding matrix and the first subcarrier precoding matrix.

With reference to any one of the fourth possible implementation manner and the fifth possible implementation manner of the third aspect, in a sixth possible implementation manner, the sending, by the sending unit, the first PMI compensation value δ specifically includes: and transmitting the first PMI compensation value delta through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).

In a fourth aspect, an embodiment of the present invention provides a feedback apparatus for precoding matrix indicator PMI, which is used in a wireless communication system with multi-carrier capability, where a base station in the wireless communication system communicates with a user equipment UE using a first subcarrier and a second subcarrier, and the base station includes: a receiving unit, configured to receive at least one common PMI, at least one first PMI and at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; a determining unit, configured to determine a precoding matrix of the first subcarrier according to the at least one common PMI and the at least one first PMI, and determine a precoding matrix of the second subcarrier according to the at least one common PMI and the second PMI.

In a first possible implementation manner of the fourth aspect, the method includes: the precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

With reference to the first possible implementation manner of the fourth aspect, in a second possible implementation manner, the method includes: the vertical precoding matrix of the first subcarrier indicated by the common PMI is:

In a third possible implementation manner of the fourth aspect, the method includes: the precoding matrix of the first subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier; the precoding matrix of the second subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the second subcarrier; the common PMI is used for indicating a long-term wideband characteristic matrix of the first subcarrier; the common PMI is further used for indicating a long-term wideband characteristic matrix of the second subcarrier; the first PMI is used for indicating a short-term narrowband characteristic matrix of the first subcarrier; the second PMI is used for indicating a short-term narrowband characteristic matrix of the second subcarrier.

With reference to the fourth aspect, or any one of the first to third possible implementation manners of the fourth aspect, in a fourth possible implementation manner, the method includes: the receiving unit is further configured to receive a first PMI compensation value δ sent by the UE, where δ is used to determine a precoding matrix of the first subcarrier together with the at least one common PMI and the at least one first PMI.

With reference to the fourth possible implementation manner of the fourth aspect, in a fifth possible implementation manner, the receiving, by the receiving unit, the first PMI compensation value δ specifically includes: the receiving unit receives the first PMI compensation value δ through a physical uplink control channel PUCCH or a physical uplink shared channel PUSCH.

Through the scheme, the invention combines a plurality of PMIs which are the same or similar among different carriers into a common PMI for feedback by utilizing the characteristic that under certain conditions, the PMIs of a plurality of carriers in a certain direction or certain characteristics have the same or similar values, thereby reducing the quantity of PMIs needing to be fed back and improving the resource utilization rate of an air interface.

Drawings

Fig. 1 is a flowchart of a feedback method for a PMI on a UE side according to an embodiment of the present invention;

fig. 2 is a flowchart of another feedback method for PMI on the UE side according to an embodiment of the present invention;

fig. 3 is a flowchart of another feedback method for PMI on the UE side according to an embodiment of the present invention;

fig. 4 is a flowchart of a feedback method for a base station PMI according to an embodiment of the present invention;

fig. 5 is a flowchart of another feedback method for PMI on the base station side according to an embodiment of the present invention;

fig. 6 is a flowchart of a feedback method for PMI on a base station side according to another embodiment of the present invention;

fig. 7 is a flowchart of another UE-side PMI feedback apparatus according to an embodiment of the present invention;

fig. 8 is a flowchart of another UE-side PMI feedback apparatus according to an embodiment of the present invention;

fig. 9 is a flowchart of another UE-side PMI feedback apparatus according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a feedback apparatus of another PMI on the base station side according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a feedback apparatus of another PMI on the base station side according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a feedback apparatus of another PMI on the base station side according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of a feedback apparatus of a PMI on a UE side according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a feedback apparatus of a base station PMI provided in an embodiment of the present invention;

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

It should be understood that the Base station related to the present invention may be, but is not limited to, a node B (NodeB) Base Station (BS), an Access Point (Access Point), a Transmission Point (TP), an Evolved node B (Evolved NodeB, eNB), or a Relay (Relay); the user equipment UE according to the present invention may include, but is not limited to, a Mobile Station (MS), a Relay (Relay), a Mobile phone (Mobile Telephone), a Mobile phone (handset), a portable device (portable equipment), a Mobile terminal, a non-Mobile terminal, and the like.

Fig. 1 is a schematic flow chart of a communication method according to an embodiment of the present invention, and relates to a feedback method of Precoding Matrix Indicator (PMI), which is used for a wireless communication system with multi-carrier capability, wherein a User Equipment (UE) communicates with a base station by using a first subcarrier and a second subcarrier.

The method specifically comprises the following steps:

step 101, the UE determines at least one common PMI, at least one first PMI and at least one second PMI, wherein the at least one common PMI and the at least one first PMI are used for indicating a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; wherein the common PMI, the first PMI and the second PMI may be 2, 3 or more than 3, respectively.

It should be understood that the present invention does not limit the specific way for the UE to determine the PMI, and the process for the UE to determine the PMI may be determined according to reference signal measurement, or may be traversed from pre-coding sub-matrices of different dimensions respectively according to measurement reference signals, so as to select a matrix with the optimal signal quality.

Step 102, the UE transmits the at least one common PMI, the at least one first PMI and the at least one second PMI to a base station in the wireless communication system.

The steps of determining at least one common PMI, at least one first PMI and at least one second PMI in step 101 will be specifically described in an exemplary manner. For example, for the first subcarrier CA1, the UE needs to feed back 4 PMIs, namely PMIs 1/2/3/4, and the 4 PMIs are used for indicating the precoding matrix of the CA 1; for the second subcarrier CA2, the UE needs to feed back 4 PMIs, namely PMIs 5/6/7/8 respectively, and these 4 PMIs are used to indicate the precoding matrix of this CA 2. In one embodiment, the PMI1 and PMI2 may collectively indicate one sub-precoding matrix W under the CA1_A1(ii) a PMI3, PMI4 may indicate another sub-precoding matrix W under CA1_B1Then from the W_A1、W_B1Determining CA1 precoding matrix W according to the determined operational relationship_A1B1. PMI5 and PMI6 may jointly indicate one sub-precoding matrix W under CA2_A2(ii) a PMI7, PMI8 may indicate another sub-precoding matrix W under CA2_B2Then from the W_A2、W_B2Determining CA1 precoding matrix W according to the determined operational relationship_A2B2. The specific determination method may be different, and the present invention is not limited thereto, and may be determined in a form of calculating parameters of a precoding matrix, for example, the UE and/or the base station may calculate W according to two parameters, i.e., PMI1 and PMI2_A1Or the UE and/or the UEThe base station stores or predetermines a table, which can query the corresponding W according to PMI1 and PMI2_A1Alternatively, the PMI1/2/3/4 may be 4 parameters, and the PMI5/6/7/8 may be 4 parameters, and the precoding matrices are directly calculated, respectively. It should be understood that the need to feed back 4 PMIs in the above one carrier is only an example, and in actual situations, other situations may occur. Each embodiment of the present application does not specify 4 PMIs. At least one PMI in the CA1 is the same as or similar to at least one PMI in the CA2 according to a certain channel condition or channel model. Then the at least one PMI of CA1 and the at least one PMI of CA2 may be determined as the common PMI. Here, the approximation here means that the two PMIs may be equal, for example, even if the two PMIs are different, the difference between the two PMIs is small, and finally the channel models of the precoding matrix of CA1 and the precoding matrix of CA2 obtained by respective calculations are within a tolerable range. For example, PMI1 corresponds to PMI5, and may be determined as a common PMI if certain conditions are satisfied_C1(ii) a PMI3 corresponds to PMI7 and can be determined as common PMI_C2Namely:

PMI₁＝PMI₅＝PMI_C1

PMI₃＝PMI₇＝PMI_C2

then, referring to step 102, the UE may feed back a common PMI: PMI_C1、PMI_C2(ii) a And a first PMI: PMI2, PMI 4; a second PMI: PMI6, PMI 8. The method for determining the common PMI is usually determined by channel characteristics, for example, PMI1 and PMI5 are used to indicate that certain matrix parameters have high correlation in certain scenarios (such as high-rise scenarios or wide-area scenarios), and the values of the parameters are equal or the difference is negligible; or PMI1 and PMI5 indicate a matrix set composed of matrixes of the same class in a table in some scenes, and other PMI2/PMI6 further indicates a matrix (which is an element in the matrix set) in the matrix set, so that PMI1 and PMI5 can be determined to be a common PMI in many same scenes₁(ii) a Similarly, the PMI3 and PMI7 may also adopt the feedback method described above. Or the base station side may directly predetermine the PMI_C1、PMI_C2Is a common PMI, and_C1stands for PMI1/PMI5, PMI_C2Representing PMI3/PMI7 and sent to the UE.

The UE may preset a rule, or determine the common PMI, the first PMI, and the second PMI with the UE through a negotiation manner, or directly indicate the common PMI, the first PMI, and the second PMI in a signaling feeding back the PMI or other signaling, and determine the common PMI, the first PMI, and the second PMI according to the indication or the preset rule. E.g. determining the PMI in a high-rise scenario₁And PMI₅Determined as a common PMI, this preset rule is also in the UE interacting with it. The indication process may also come from other UEs or other network side devices.

It should be understood that, in step 101, the UE determines that the specific order of the at least one common PMI, the at least one first PMI and the at least one second PMI may be different, and the present invention provides different embodiments:

embodiment 1, the PMIs of different carriers are determined first, and then the common PMI and the non-common PMI are determined:

the UE may determine a plurality of PMIs corresponding to a precoding matrix of the first subcarrier CA1 and a plurality of PMIs corresponding to a precoding matrix of the second subcarrier CA2, respectively, determine the at least one common PMI that may be a common PMI among the plurality of PMIs corresponding to CA1 and the plurality of PMIs corresponding to CA2, and determine the remaining PMIs that are not determined as common PMIs and corresponding to CA1 as the at least one first PMI; the remaining PMIs which are not determined as common PMIs and to which CA2 corresponds are the second PMIs.

In embodiment 2, the common PMI is directly determined according to a scene or other preset rules:

the UE may determine a plurality of PMIs corresponding to a precoding matrix of the first subcarrier CA1, determine at least one of them as a common PMI according to a channel condition, a usage scenario, or a preset rule, and determine other PMIs not determined as a common PMI in CA1 as the at least one first PMI; and then determining the at least one second PMI corresponding to the second subcarrier CA2 precoding matrix. For example, the precoding matrix of CA1 is composed of a vertical precoding matrix and a horizontal precoding matrix, the precoding matrix of CA2 is also composed of a vertical precoding matrix and a horizontal precoding matrix, and it is necessary to feed back the PMI of the vertical precoding matrix and the PMI of the horizontal precoding matrix of CA1 and CA2, and in a certain scenario, for example, a high-rise scenario may be possible, the vertical precoding matrix of CA1 and the vertical precoding matrix of CA2 may be determined as the common PMI. In the UE determination process, it may be determined that the PMI of the CA1 vertical direction precoding matrix is the common PMI, then it is determined that the CA1 horizontal direction precoding matrix is the at least one first PMI, and it is determined that the CA2 horizontal direction precoding matrix is the at least one second PMI.

In embodiment 3, the first PMI and the common PMI are determined first, and then the second PMI is determined:

the UE may determine the at least one common PMI in the correspondence between the first subcarrier CA1 precoding matrix and the second subcarrier CA2 precoding matrix directly according to a preset rule or a usage scenario, and then determine the at least one first PMI and the at least one second PMI. For example; the precoding matrix of CA1 is composed of precoding matrices in the vertical direction and the horizontal direction, the precoding matrix of CA2 is also composed of precoding matrices in the vertical direction and the horizontal direction, it is necessary to feed back the PMI of the vertical direction precoding matrix of CA1 and CA2 and the PMI of the horizontal direction precoding matrix, and in a certain scenario, the PMI corresponding to the precoding matrices in the vertical direction of CA1 and CA2 is highly similar, and can be determined as the common PMI. In the determination process of the UE, the common PMI is directly determined, and this value may be preset for a certain situation or determined jointly according to CA1 and CA 2. And then determining the CA1 horizontal direction precoding matrix as the at least one first PMI, and determining the CA2 horizontal direction precoding matrix as the at least one second PMI.

It should be understood that the present invention is not limited to the specific implementation steps given in the above embodiments 1-3, but may be other specific implementations for determining the at least one common PMI.

It should be understood that the present invention is not limited to the specific method for determining the PMI corresponding to each precoding matrix, and may be that the matrix with the best signal quality is selected by respectively traversing from precoding sub-matrices with different dimensions. For example, the UE measures CA1 optimal precoding matrix W1, W2 and CA2 optimal precoding matrix W3 and W4 based on CA1 and CA2, where W1 and W2 may be determined from different codebooks, i.e., precoding matrix sets, and W3 and W4 may be determined from different codebooks, i.e., precoding matrix sets, respectively.

In one embodiment, different RIs correspond to different PMI tables one to one, and after the UE determines the value of the RI, the UE determines a PMI table corresponding to the value of the RI from the PMI tables, where the PMI table may include a corresponding relationship between a PMI and a precoding matrix and/or a corresponding relationship between a PMI and a precoding sub-matrix. The PMI list may further include a relationship between a result obtained by the UE according to the measurement of the reference signal and the precoding matrix, and/or a relationship between a result obtained by the UE according to the measurement of the reference signal and the precoding sub-matrix. And determining a PMI value corresponding to one CA according to at least one matrix in the PMI table. In the process of determining the PMI value, the signal quality corresponding to all the matrices in the determined PMI table may be measured in a traversing manner to determine an optimal matrix, and then a PMI value corresponding to the optimal matrix is determined, where the PMI value is a PMI value corresponding to the CA. In another embodiment, the PMI may be determined directly by determining the precoding matrix. The PMI table may be a specific table or a plurality of corresponding relationship sets stored in the UE.

It should be understood that the present invention is not limited to the determination process of each PMI, and may be, but not limited to, the result of negotiation between the UE and the base station, or a rule predetermined by both parties, or directly determined by the UE, or notified to the UE by the base station, or a specific determination manner determined according to an application scenario.

By the PMI feedback method described in this embodiment, in different scenarios, the PMIs in some items among different subcarriers are the same, and the PMIs corresponding to the respective PMIs of the different subcarriers are integrated, so that the UE only feeds back a common PMI once in a process of determining a precoding matrix, and the common PMI is used for indicating the precoding matrices of the different subcarriers, so that the base station determines the precoding matrices of the respective subcarriers respectively through the common PMI and the non-common PMIs (in this embodiment, the first PMI and the second PMI) under the different subcarriers. In this embodiment, the UE sends, to the base station, a PMI that can be used by each subcarrier in a common manner and a non-common PMI that cannot be used in a common manner, where in a process of determining two subcarrier precoding matrices at a time, a total number of fed-back PMIs is K to indicate Q precoding matrices under two subcarriers, and the number K of fed-back PMIs smaller than the number of Q, so as to achieve a purpose of saving channel resources. It should be understood that the common PMI, the first PMI and the second PMI do not necessarily exist independently in the present invention, and may be referred to as the common PMI, the first PMI and the second PMI in different fields of the same message.

It should be understood that, for different scenarios, the common PMI and the non-common PMI may be determined according to specific scenario characteristics, so as to achieve the purpose of saving channel resources. The following will specifically describe the feedback method of the precoding matrix indicator PMI shown in fig. 1 in different scenarios:

in one embodiment, for a 3D MIMO scenario or the like, the precoding matrix of the first subcarrier is a kronecker product of a first precoding matrix W1 of the first subcarrier and a second precoding matrix W2 of the first subcarrier; PMI1 is one of the PMI of W1 and the PMI of W2; PMI2 is the other of the PMI of W1 and the PMI of W2; the precoding matrix of the second subcarrier is a kronecker product of a third precoding matrix W3 of the second subcarrier and a fourth precoding matrix W4 of the second subcarrier; the PMI1 is one of the PMI of W3 and the PMI of W4; PMI3 is the other of the PMI of W3 and the PMI of W4. When W1 is the vertical precoding matrix of the first subcarrier, W2 is the horizontal precoding matrix of the first subcarrier; when W3 is the vertical precoding matrix of the second subcarrier and W4 is the horizontal precoding matrix of the second subcarrier.

Fig. 2 shows a specific embodiment of the present invention. The precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

The method specifically comprises the following steps:

step 201, a user equipment UE determines at least one common PMI, at least one first PMI and at least one second PMI, wherein the at least one common PMI is used for indicating a vertical direction precoding matrix; the at least one first PMI is used for indicating a first subcarrier horizontal direction precoding matrix; the at least one second PMI is used for indicating a second subcarrier horizontal direction precoding matrix.

Step 202, the UE sends the at least one common PMI, the at least one first PMI and the at least one second PMI to a base station, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier, and the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

For 3D MIMO or similar scenarios, the antenna distribution may be regarded as a vertical direction arrangement and a horizontal direction arrangement, so the precoding matrix of the first subcarrier may be regarded as a vertical direction precoding matrix and a horizontal direction precoding matrix, and the precoding matrix of the second subcarrier may be regarded as a vertical direction precoding matrix and a horizontal direction precoding matrix, for example: when the precoding matrix of the first subcarrier is a kronecker product of a first precoding matrix W1 and a second precoding matrix W2 of the first subcarrier, and the precoding matrix of the second subcarrier is a kronecker product of a third precoding matrix W3 and a fourth precoding matrix W4 of the second subcarrier, it is satisfied that:

wherein, W_(CA1)A precoding matrix, W, for the first subcarrier_(CA2)A precoding matrix, W, for the second subcarrier_(CA1，1)Precoding matrix for first subcarrier vertical direction, W_(CA1，2)A precoding matrix is horizontally arranged for the first subcarrier; w_(CA2，1)For the vertical precoding matrix, W, of the second subcarrier_(CA2，2)And precoding a matrix for the horizontal direction of the second subcarrier. Since the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction in a general scenario, the vertical direction is similar to a single-path channel, and the vertical direction channel can be determined to be a single-path channel model, and further, the vertical direction channel can be similar or equal to the PMI equality corresponding to the precoding matrix W in the vertical direction under different subcarriers that the UE needs to feedback_(CA1，1)PMI of_(CA1，1)And for indicating the second subcarrier vertical direction precoding matrix W_(CA2，1)PMI of_(CA2，1)Equal, i.e.:

PMI_(CA1，1)＝PMI_(CA2，1)＝PMI_C

in such a case, the PMI may be determined_CIs the at least one common PMI. Correspondingly, determining a precoding matrix W for indicating the horizontal direction of the first subcarrier_(CA1，2)PMI of_(CA1，2)Is the at least one first PMI; determining a precoding matrix W for indicating the horizontal direction of the second subcarrier_(CA2，2)PMI of_(CA2，2)Is the at least one second PMI. Based on the above condition, i.e. approximating a single path channel in the vertical direction, it can be guaranteed that a PMI is being transmitted_C、PMI_(CA1，2)、PMI_(CA2，2)According to the PMI_CAnd PMI_(CA1，2)Indicates the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Indicates the W_(CA2，2). Enabling the base station to follow the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). The determination process here may be determined by negotiation of the base station, or may be notified to the base station after receiving an indication from the base station or other devices or determining itself.

In one embodiment, the vertical precoding matrix and/or the horizontal precoding matrix of the first subcarrier indicated by the common PMI is:

According to the description of the above embodiments, when the precoding matrix of the first subcarrier can be decomposed into the vertical precoding matrix and the horizontal precoding matrix, the PMI indicates the vertical precoding matrix and the horizontal precoding matrix respectively, and the UE sends, to the base station, the PMI that each subcarrier can be commonly used and the non-common PMI that cannot be commonly used by using the characteristic that the angular spread of the vertical beam of the PMI is relatively small, wherein, in the process of determining two subcarrier precoding matrices at a time, the total number of the fed-back PMIs K to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs smaller than the number of Q, so as to achieve the purpose of saving channel resources. It should be understood that, if the angular spread of the horizontal directional beam of the antenna is much smaller than the angular spread of the vertical directional beam due to a change in the position, channel characteristics, or other conditions of the antenna, the horizontal directional channel may be determined as a model approximating a single-path channel, the PMI for indicating the horizontal directional precoding matrix of the first subcarrier may be determined as the at least one common PMI, the PMI for indicating the vertical directional precoding matrix of the first subcarrier may be determined as the at least one first PMI, and the PMI for indicating the vertical directional precoding matrix of the second subcarrier may be determined as the at least one second PMI. The specific steps and flow are the same as those in the above embodiments, and are not described herein again.

It should be understood that the judgment of the channel model may be a condition determined by reaching a certain condition, and may be directly configured or calculated and determined according to the base station or the UE.

In one embodiment, when the difference between PMIs in some entries of different subcarriers is smaller than a certain threshold in some cases, such a PMI may also be determined as a common PMI. It should be understood that the present invention does not limit the number of subcarriers, and as long as at least one PMI of each of a plurality of subcarriers can be determined as the common PMI according to a preset rule or a certain condition, the number of PMI feedbacks can be reduced, thereby achieving the purpose of saving channel resources.

In an embodiment, in the W1 and the W2, a precoding matrix of a first subcarrier corresponding to the common PMI is a vector, and/or:

in the W3 and the W4, a precoding matrix of a first subcarrier corresponding to the common PMI is a vector.

For example, the precoding matrix of the first subcarrier corresponding to the common PMI is:

wherein N is a positive integer, k is an integer greater than or equal to 0 and less than or equal to N-1; m is the length of the precoding matrix W corresponding to the common PMI, and T represents the transpose of the matrix. It should be understood that the transpose is used here only for convenience of representing the vector, which may be an array during the call of the implementation. Alternatively, the above formula may be stored in the system in the form of a matrix. It can be seen that W_pIs a vector truncated in a fourier matrix, it should be understood that the precoding matrix of the first subcarrier is not limited to the W_pIn the form shown, the vectors may be obtained by taking the different positions from the following fourier matrix:

in another embodiment, another method for PMI feedback is introduced. The method may be, but is not limited to, an antenna scenario for 2d mimo. The precoding matrix of the first subcarrier is a first precoding matrix W of the first subcarrier₅And a second precoding matrix W₆The product of (a); the common PMI is the W₅PMI of (a) and the W₆One of the PMIs of (a); the first non-common PMI is the W₅PMI of (a) and the W₆Another one of the PMIs of (1); the precoding matrix of the second subcarrier is the first precoding matrix W of the first subcarrier₇And a second precoding matrix W₈The product of (a); the common PMI is the W₇PMI of (a) and the W₈One of the PMIs of (a); the first non-common PMI is the W₇PMI of (a) and the W₈Another one of the PMIs of (1). For example, the precoding matrix of the first subcarrier is a long-term wideband characteristic matrix (the W) of the first subcarrier₅) And a short-term narrow-band characteristic matrix (the W)₆) The product of (a); the precoding matrix of the second subcarrier is a long-term wideband characteristic matrix (the W) of the second carrier₇) And a short-term narrow-band characteristic matrix (the W)₈) The product of (a);

the common PMI is used for indicating a long-term wideband characteristic matrix of the first subcarrier; the common PMI is further used for indicating a long-term wideband characteristic matrix of the second subcarrier;

the first PMI is used for indicating a short-term narrowband characteristic matrix of the first subcarrier;

the second PMI is used for indicating a short-term narrowband characteristic matrix of the second subcarrier.

Next, a specific embodiment is given, and this embodiment specifically provides a method for forming a codebook and a method for determining the codebook. For certain scenarios, the first subcarrier may be decomposed into the product of the W5 and the W6, and the second subcarrier may be decomposed into the W₇And said W₈Product ofWherein, the W₅Representing long term/wideband characteristics of the first subcarrier precoding matrix; the W is₆Representing short-term/narrow-band characteristics of the first sub-carrier; the W is₇Representing long term/wideband characteristics of the second subcarrier precoding matrix; the W is₈Representing short-term/narrow-band characteristics of the second sub-carrier. Namely, the following conditions are satisfied:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

wherein, W'_(CA1)A precoding matrix for the first subcarrier; w'_(CA2)A precoding matrix for the second subcarrier; next, first, W 'is given'_(CA1)And said W₅PMI (PMI) of response₅) And said W₆Corresponding PMI (PMI)₆) Of (c), corresponding to, W'_(CA2)And said W₇Corresponding PMI₇And said W₈Corresponding PMI₈The relationship of (c) may be the same. If codebook set B is:

B＝[b₀，b₁，...b₃₁]

wherein, b₀、b₁…b₃₁Is a column vector, and the 1+ mth row 1+ n column elements [ B ] in B]_1+m，1+nComprises the following steps:

it should be understood that, in this example, for convenience of describing each element therein, the codebook set B is in a matrix form, and the codebook set may also be a column in B, and constitute a set in a vector form.

The PMI₅For instructing the base station to select at least one column from the codebook set and to form the W₅In particular, k is PMI₅And is an integer value with a value range of 0-15, which is used for selecting (indicating) 4 columns from B to obtain X^(k)：

X^(k)＝[b_{2k mod 32}b_{(2k+1)mod 32}b_{(2k+2)mod 32}b_{(2k+3)mod 32}]

Where mod is the modulo symbol.

Further obtaining said W₅＝W₅ ^(k)：

According to the W₅ ^(k)Constructing codebook set C₁：

C₁＝{W₁ ⁽⁰⁾，W₁ ⁽¹⁾，W₁ ⁽²⁾，…，W₁ ⁽¹⁵⁾}

W₅ ^(k)The matrix characterizes the long-term wideband properties of the channel, on the other hand, another PMI (for convenience, this PMI is referred to as PMI₆) For indicating to the base station from codebook set C₁At least one element (codebook) and constructing the W₆. Constructing different codebook sets C for different RI₂. For example, when RI is 1, the codebook set may be configured as follows:

wherein, Y ∈ { α₁，α₂，α₃，α₄}. α may be a vector with only some positions 1 per column.

When RI is 2, the codebook set may be configured as follows:

wherein, Y₁，Y₂Arrangement order of (Y)₁，Y₂) May be α₁To α₄May also be in the form of:

(Y₁，Y₂)∈{(α₁，α₁)，(α₂，α₂)，(α₃，α₃)，(α₄，α₄)，(α₁，α₂)，(α₂，α₃)，(α₁，α₄)，(α₂，α₄)}

when the RI is 1, according to PMI₆From C_2，1Determining an element as W₆(ii) a When the RI is 2, according to PMI₆From C_2，2Determining an element as W₆。

Correspondingly, the formula:

W′_(CA1)＝W₅×W₆

can represent a selection matrix W₆From W₅The superposition of some columns is selected to form a precoding matrix corresponding to the first subcarrier. W is as described above₅ ^(k)A matrix comprising 4 beams, representing long-term wideband channel characteristics, may be shared by a first subcarrier and a second subcarrier, and thus may share one W for different subcarriers₅And each subcarrier can independently feed back a matrix W embodying short-term narrow-band characteristics₆Corresponding PMI₆And a matrix W embodying short-term narrow-band characteristics₈Corresponding PMI₈. It should be understood that the specific values in the above example are only one example given for the sake of convenience, and may be varied by the antenna port, rank indication, or other parameters during the specific application. And the codebook and the selection manner are exemplary descriptions, and the invention claims codebooks and manners of selecting codebooks in other forms.

W 'mentioned above'_(CA1)＝W₅×W₆And W'_(CA2)＝W₇×W₈Formally, it may be applied in particular in 2D MIMO scenarios, where the precoding matrix may specifically be represented by a product of the long-term wideband characteristic and the short-term narrowband characteristic of the signal. Fig. 3 shows the specific implementation steps when one precoding matrix can be shared due to its long-term wideband nature of the subcarriers.

Specifically, in step 301, the UE determines at least one common PMI, at least one first PMI, and at least one second PMI, where the at least one common PMI is used to indicate that a long-term wideband characteristic matrix is embodied; the at least one first PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in a first subcarrier; the at least one second PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in the second subcarrier.

Step 302, the UE sends the at least one common PMI, the at least one first PMI and the at least one second PMI to a base station, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier, and the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

It should be understood that the present invention is not limited to the mutual integration among the embodiments, and in the specific order and the specific manner of determining the PMI, the embodiments in fig. 2 and 3 may be implemented as in the embodiment 1-3 shown in fig. 1, and are not described herein again.

For convenience of understanding, the present invention further provides a specific implementation manner for specifically determining the PMI by looking up a table, which can be used in a scenario where the precoding matrix is formed by multiplying the first subcarrier precoding matrix and the second subcarrier precoding matrix. It should be understood that the table lookup in the present invention may be a table stored in the UE or the base station, the table includes the corresponding relationship between the PMI and the matrix, and the table may be multiple in consideration of specific applications, so that the PMI and the specific precoding sub-matrix correspond to different tables under different RI values or other parameters. The UE acquires information required in the table; or an array or a relationship for querying the PMI value corresponding to the corresponding precoding matrix. It should be understood that the specific form of the table may be various, and may be a mapping relation or a functional relation stored in the UE or the base station, and the present invention is not limited thereto. For convenience of description, the present embodiment is described in a table form. The UE determines the long-term wideband matrix corresponding to the first subcarrier and the second subcarrier, and determines the corresponding table in the corresponding rank, for example, the value range of the rank indication is 1-4, then it determines that the corresponding table is needed in tables 1 to 4 (table 1 corresponds to rank indication 1, table 2 corresponds to rank indication 2, table 3 corresponds to rank indication 3, and table 4 corresponds to rank indication 4):

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Determining one of tables 1-4 according to the RI, determining long-term wideband characteristic matrix of the CA1 and the CA2 according to specific use scene in the determined table, and further determining the common PMI (i) according to the long-term wideband characteristic matrix₁) According to the short-term narrow-band characteristic matrix of CA1 and the PMI corresponding to the short-term narrow-band characteristic matrix of CA2, respectively determining the first PMI (i) corresponding to CA1₂) And the second PMI (i) corresponding to the CA2₂') to transmit the values of i1, i2, i 2' to the base station.

Determining the common PMI (i) of the CA1 and the CA2 in the determined table₁) The specific manner of the value of (i) can be determined according to the channel characteristics, and in tables 1 to 4, PMI (i)₁)，PMI(i₂) For determining

Due to PMI (i)₁) The determined characteristic corresponds to a short-term narrow-band characteristic in a physical sense, and values may be the same in different CAs, so in this embodiment, PMI (i) of CA1 is used₁) PMI (i) of CA2₁) May be a common PMI.

In addition to using the PMI corresponding to the short-term narrowband characteristic matrix as the common PMI, the PMI value of the long-term wideband characteristic matrix corresponding to CA1 and the PMI value of the long-term wideband characteristic matrix corresponding to CA2 may be separately confirmed, and one of the two may be selected as the common PMI. It should be understood that, in the case of multiple CAs, for example, CA1, CA2, and CA3, it may also determine a common PMI, and for example, the PMI corresponding to the short-term narrowband characteristic matrix of CA1, CA2, and CA3 may be used as the common PMI, and the UE may only feed back 1 time of the common PMI, and may indicate the short-term narrowband characteristic matrix in three carriers, so as to achieve the purpose of further saving resources. Of course, the present embodiment is also applicable to the long-term wideband characteristic and the vertical and horizontal precoding matrices, and will not be described herein again. Of course, there may be multiple PMIs common to multiple CAs.

Fig. 3 illustrates an embodiment, according to the long-term wideband characteristic matrix of the first subcarrier precoding matrix in the table may be shared with other subcarriers, PMIs corresponding to different subcarriers may be used as a common PMI to transmit the common PMI once under the condition that two precoding matrices of different subcarriers are determined, a non-common PMI that cannot be commonly used by each subcarrier is transmitted to the base station to indicate 4 precoding matrices of subcarriers under 2 subcarriers (that is, a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier and the second subcarrier, respectively), and the number k of PMIs fed back is smaller than the number of all 4 precoding matrices that can be determined by the k PMIs, so as to achieve the purpose of saving channel resources. It should be understood that the long-term wideband characteristic matrix according to the first subcarrier precoding matrix in the table may be shared with other subcarriers, and in other scenarios, a situation that the short-term narrowband characteristic matrix may be shared with other subcarriers may also occur, which corresponds to the determination method in this embodiment and is not described herein again.

It should be understood that the embodiments of the present invention all determine PMIs under two subcarriers, and the present invention claims that when the number of subcarriers is more than two, there is a PMI that can be shared with other subcarriers in the respective PMIs of the two subcarriers, and meanwhile, there may also be several subcarriers in the subcarriers that are different from PMIs fed back by any one of the at least two subcarriers, and PMIs corresponding to the several subcarriers adopt a form of separate feedback. For example, there are 3 subcarriers CA1, CA2, CA3, wherein although there are one or more common PMIs for CA1 and CA2, the UE cannot determine any one PMI for CA3 and any one PMI for CA2 and CA1 as a common PMI, and then the UE will feed back all PMIs for CA3 alone.

Next, still another embodiment will be described with respect to a method of specifically determining a common PMI of the present invention. According to the embodiments shown in fig. 1-3, when a certain PMI of the first subcarrier is determined_aCertain PMI with a second subcarrier_bDifferent, but will PMI_aPMI used as second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the PMI can be directly determined_aIs the common PMI; correspondingly, when PMI is to be transmitted_aPMI used for indicating second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the PMI can also be directly determined_aIs the common PMI; or when using a PMI_cWhen used as a common PMI for the first subcarrier and the second subcarrier, the PMI may be used_aAnd the PMI_bIn this case, when the channel characteristics of the system can satisfy a certain condition, the PMI may be directly determined_cAs the at least one common PMI. Optionally, the UE may determine the at least one common PMI, the at least one first PMI, the at least one second PMI, and a compensation value δ, where the at least one common PMI and the at least one first PMI are used to determine a precoding matrix of the first subcarrier; the at least one common PMI, the at least one second PMI, and the delta collectively indicate a second subcarrierAnd transmitting the at least one common PMI, the at least one first PMI, the at least one second PMI, and one compensation value δ to the base station. It should be understood that the PMI of the second subcarrier may also be determined as the at least one common PMI, and a compensation value δ 'may be sent, and the precoding matrix of the first subcarrier may be determined according to the at least one common PMI, the δ', and the at least one first PMI; determining a precoding matrix of the second subcarrier according to the at least one common PMI and the second PMI. Generally, the number of bits or resources occupied by δ is smaller than the number of bits or resources occupied by one PMI. In this case, the purpose of indicating the precoding matrix of two subcarriers more accurately can be achieved while saving resources.

Optionally, the UE determines and sends the first PMI compensation value δ₁And/or a second PMI compensation value delta₂Said delta₁A precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the₂A precoding matrix for co-determining the second subcarrier with the at least one common PMI and the at least one second PMI.

The UE determines and transmits a first PMI compensation value delta₁And/or a second PMI compensation value delta₂There are three cases:

case 1:

the UE determines the delta₁And delta₂And transmitting said delta to said base station₁And delta₂；

Case 2:

the UE determines the delta₁And transmitting said delta to said base station₁；

Case 3:

the UE determines the delta₂And transmitting said delta to said base station₂。

It is to be understood that δ₁And delta₂The order of the PMIs to be fed back to the UE is not limited, and may be transmitted simultaneously or sequentially. Corresponding to different scenes according to the common PMIThe invention provides three specific embodiments:

embodiment 4:

when the precoding matrix of the first subcarrier is a kronecker product of a first precoding matrix W1 and a second precoding matrix W2 of the first subcarrier and the precoding matrix of the second subcarrier is a kronecker product of a third precoding matrix W3 and a fourth precoding matrix W4 of the second subcarrier:

since the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction, the vertical direction is similar to a single path channel, and the vertical direction channel can be determined to be similar to a single path channel model, as an example, in embodiment 4, W is determined_(CA1，1)Corresponding PMI_(CA1，1)Determining said PMI as one of said common PMIs_(CA1，1)And said W_(CA2，1)Corresponding PMI_(CA2，1)May be represented by delta_aAnd (4) determining. Determining W_(CA1，2)Corresponding PMI_(CA1，2)Determining W for the first PMI_(CA2，2)Corresponding PMI_(CA2，2)As the second PMI, here, the common PMI and the first PMI are used to determine (indicate) W, respectively_(CA1，1)And said W_(CA1，2)The common PMI, the delta_aDetermining the W_(CA2，1)Said second PMI said W_(CA2，2)To identify the first subcarrier precoding matrix W_(CA1)、W_(CA2). It should be understood that PMI is determined_(CA2，1)As the common PMI, δ is correspondingly used_a' and the common PMI indicate the W_(CA1)The method can be the same as the above method, and is not described again.

Embodiment 5:

when the precoding matrix of the first subcarrier is the product of the first precoding matrix W5 and the second precoding matrix W6 of the first subcarrier; under the scenario that the precoding matrix of the second subcarrier is the product of the first precoding matrix W7 and the second precoding matrix W8 of the first subcarrier:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

the matrix W5 representing the long-term wideband channel characteristics of CA1 may be implemented as PMI₅Indication, the matrix W7 representing the long-term wideband channel characteristics of CA2 may be PMI₅And a compensation value delta_bIndicating that, as an example, a PMI (PMI) corresponding to W5 is determined₅) As the common PMI, a PMI (PMI) corresponding to W6₆) A PMI (PMI) corresponding to W8 as the first PMI₈) For the second PMI, in one embodiment, the common PMI is used for determining (indicating) the W5, the first PMI is used for determining (indicating) the W6, and the second PMI is used for indicating the W8, the common PMI, and the δ_bFor indicating the W7, the W5, W6 for determining the W'_(CA1)The W7, the W8 are used to determine the W'_(CA2)(ii) a In another embodiment, the corresponding table in tables 1-4, i in the common PMI corresponding table, is determined according to rank indication₁I in the first PMI correspondence table₂Determining a precoding matrix W corresponding to the first subcarrier; the common PMI and the delta_b' value obtained after calculation corresponds to i in table₁I in the second PMI correspondence table₂Determining a precoding matrix W corresponding to the second subcarrier₂. It should be understood that the method for determining the PMI7 as the common PMI is the same as the above embodiments, and is not described again.

Embodiment 6:

according to the above embodiment, two compensation values, δ, can also be given simultaneously_cAnd delta_d. In this case, the δ_cA precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the_dFor and said at least one male memberAnd the PMI and the at least one second PMI jointly determine a precoding matrix of the second subcarrier.

It should be understood that when the compensation of the compensation value is involved, the base station and the UE may specify that the compensation value is not compensated for in a certain feedback, and the compensation may not be adopted through signaling or other convention.

It should be understood that, the above-mentioned various embodiments for determining the compensation value give a basis or an order of determination, the specific determination method is not limited by the present invention, and the determination manner of the compensation value may be different according to the allocated bit number, for example, when the common PMI is used to indicate that the error of the first subcarrier precoding matrix and the second subcarrier precoding matrix is not large (i.e. can be within a tolerance range), 1 bit may be allocated, 0 represents no compensation, 1 represents compensation, and the specific compensation value may be predefined; in one embodiment, PMI_XAnd PMI_YFor indicating a first subcarrier precoding matrix, PMI_ZAnd PMI_WFor indicating the second subcarrier precoding matrix. Indicating PMI when it is determined that common PMI can be simultaneous PMI_XAnd PMI_ZI.e. common PMI and PMI_Y(PMI here)_YEquivalent to the first PMI) indicates a precoding matrix of a first subcarrier; using common PMI and PMI_Z(PMI here)_WEquivalent to the second PMI) indicates a precoding matrix of a second subcarrier; when determining PMI_XWhen the PMI is equal to 7, the PMI may be identical to the first PMI (may be a PMI in this embodiment)_Y) Jointly indicate the first subcarrier precoding matrix if PMI_WCorresponding characteristics and PMI_XIs not very different or the same, i.e., PMI can be determined_WAt this point, as long as the UE determines δ to be 0 and sends δ, it can be informed that compensation is not needed; however, if the system determines to use PMI_W10 and the second PMI (which may be a PMI in this embodiment)_W) When the second subcarrier precoding matrix is indicated together, then, using the common PMI of 7 and the second PMI to indicate the second subcarrier precoding matrix together may bring about a relatively large error. However, if the offset value δ preset by the system is 1 to represent offset 3, then 1 bit can accurately indicate that the base station side needs to use the common PMI to be equal toAnd 7, compensating for 3, and determining a second subcarrier precoding matrix together with the second PMI. It should be understood that, for this example, in some scenarios, if the compensation value δ of the system preset is 1 to represent the compensation 2, the value indicated jointly by the common PMI and the compensation value is 9, which is also acceptable if within some tolerable range.

It should be understood that the above method of determining and transmitting the compensation value is merely an example, and the determination of the compensation value may be combined with any of the embodiments of transmitting the compensation value, and other embodiments of the present invention, within the scope of logic.

By utilizing the single-path characteristics in the vertical direction of different subcarriers or the similarity of the long-term broadband characteristics of different subcarriers, the vertical direction precoding matrix or the long-term broadband characteristic precoding matrix of a certain subcarrier can be determined as the common PMI under different channel models, and then a compensation value delta is determined; indicating a vertical direction precoding matrix or a long-term wideband characteristic precoding matrix of another subcarrier according to the delta and the common PMI. And indicating the precoding matrixes under different subcarriers according to the first PMI and the second PMI, thereby saving channel resources and improving indication precision.

Fig. 4 is a schematic flow chart of a communication method according to an embodiment of the present invention, and relates to a feedback method of precoding matrix indicator PMI, which is used for a wireless communication system with multi-carrier capability, wherein a base station communicates with the base station by using a first subcarrier and a second subcarrier.

The method specifically comprises the following steps:

step 401, the base station receives at least one common PMI, at least one first PMI and at least one second PMI;

step 402, the base station determines a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

Hereinafter, the steps of receiving in step 401 and determining at least one of the common PMI, the at least one first PMI, and the at least one second PMI in step 402 will be specifically described in an exemplary manner. For example, for the first subcarrier CA1, the base station needs to determine 4 PMIs to be PMI1/2/3/4, respectively, where the 4 PMIs are used to indicate the precoding matrix of the CA 1; for the second subcarrier CA2, the base station needs to determine 4 PMIs to be PMI5/6/7/8 respectively, and these 4 PMIs are used to indicate the precoding matrix of this CA 2. In one embodiment, the PMI1 and PMI2 may collectively indicate one sub-precoding matrix W under the CA1_A1(ii) a PMI3, PMI4 may indicate another sub-precoding matrix W under CA1_B1Then from the W_A1、W_B1Determining CA1 precoding matrix W according to the determined operational relationship_A1B1. PMI5 and PMI6 may jointly indicate one sub-precoding matrix W under CA2_A2(ii) a PM17, PMI8 may indicate another sub-precoding matrix W under CA2_B2Then from the W_A2、W_B2Determining CA1 precoding matrix W according to the determined operational relationship_A2B2. The specific determination method may be different, and the present invention is not limited thereto, and may be determined in a form of calculating parameters of a precoding matrix, for example, the UE and/or the base station may calculate W according to two parameters, i.e., PMI1 and PMI2_A1Or, the UE and/or the base station may store or predetermine a table, and may query the corresponding W according to PMI1 and PMI2_A1Alternatively, the PMI1/2/3/4 may be 4 parameters, and the PMI5/6/7/8 may be 4 parameters, and the precoding matrices are directly calculated, respectively. It should be understood that the need to feed back 4 PMIs in the above one carrier is only an example, and in actual situations, other situations may occur. Each embodiment of the present application does not specify 4 PMIs. At least one PMI in the CA1 is the same as or similar to at least one PMI in the CA2 according to a certain channel condition or channel model. Then the at least one PMI of CA1 and the at least one PMI of CA2 may be determined as the common PMI. Wherein, approximately here means can be equal, for example, even if two PMIs are different, the difference between the two PMIs is small, and the final basisThe channel models of the stations according to the respective calculated precoding matrix of CA1 and the precoding matrix of CA2 are within a tolerable range. For example, PMI1 corresponds to PMI5, and may be determined as a common PMI if certain conditions are satisfied_C1(ii) a PMI3 corresponds to PMI7 and can be determined as common PMI_C2Namely:

PMI₁＝PMI₅＝PMI_C1

PMI₃＝PMI₇＝PMI_C2

then, referring to step 401, the base station may receive a common PMI: PMI_C1、PMI_C2(ii) a And a first PMI: PMI2, PMI 4; a second PMI: PMI6, PMI 8. The method for determining the common PMI is usually determined by channel characteristics, for example, PMI1 and PMI5 are used to indicate that certain matrix parameters have high correlation in certain scenarios (such as high-rise scenarios or wide-area scenarios), and the values of the parameters are equal or the difference is negligible; or PMI1 and PMI5 indicate a matrix set composed of matrices of the same class in a table in some scenarios, and other PMI2/PMI6 further indicates a matrix (which is an element in the matrix set) in the matrix set, so that PMI1 and PMI5 can be determined as a common PMI in many same scenarios₁(ii) a Similarly, the PMI3 and PMI7 may also be indicated as described above. Or the base station side may directly predetermine the PMI_C1、PMI_C2Is a common PMI, and_C1stands for PMI1/PMI5, PMI_C2Representing PMI3/PMI7 and sent to the UE.

The base station may preset a rule, or determine a common PMI, a first PMI, and a second PMI with the UE through a negotiation manner, or may directly indicate the common PMI, the first PMI, and the second PMI in a signaling feeding back the PMI or other signaling, and the base station determines the precoding matrix according to the indication. E.g. determining the PMI in a high-rise scenario₁And PMI₅Determined as a common PMI, this preset rule is also in the UE interacting with it. The indication process may also come from other UEs or other network side devices.

It should be understood that, in step 402, the specific process of determining, by the base station, the precoding matrix of the first subcarrier and the precoding matrix of the second subcarrier according to the at least one common PMI, the at least one first PMI and the at least one second PMI may be different PMI tables corresponding to different RIs one to one, after the base station determines the value of the RI, the base station determines, from the plurality of PMI tables, a PMI table corresponding to the value of the RI, where the PMI table may include a corresponding relationship between a PMI and a precoding matrix and/or a corresponding relationship between a PMI and a precoding submatrix. And determining a precoding matrix of CA1 according to the common PMI and the first PMI, or determining a precoding matrix corresponding to CA2 according to the common PMI and the second PMI. The PMI table may be a specific table or a plurality of corresponding relationship sets stored in the UE and/or the base station.

By the PMI receiving and determining method described in this embodiment, it may be used that in different scenarios, PMIs in some items between different subcarriers are the same, and respective PMIs corresponding to different subcarriers are integrated, so that the base station receives a common PMI only once in a process of determining a precoding matrix, where the common PMI is used to indicate precoding matrices of different subcarriers, so that the base station determines the precoding matrices of each subcarrier respectively through the common PMI and non-common PMIs (in this embodiment, a first PMI and a second PMI) under each different subcarrier. In this embodiment, the base station receives a PMI that can be commonly used by each subcarrier and a non-common PMI that cannot be commonly used, wherein in the process of determining two subcarrier precoding matrices at a time, the total number of the received PMIs K to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs smaller than the number of Q, so as to achieve the purpose of saving channel resources. It should be understood that the common PMI, the first PMI and the second PMI do not necessarily exist independently in the present invention, and may be referred to as the common PMI, the first PMI and the second PMI in different fields of the same message.

Fig. 5 shows a specific embodiment of the present invention. The precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

The method specifically comprises the following steps:

step 501, a base station receives at least one common PMI, at least one first PMI and at least one second PMI, wherein the at least one common PMI is used for indicating a vertical direction precoding matrix; the at least one first PMI is used for indicating a first subcarrier horizontal direction precoding matrix; the at least one second PMI is used for indicating a second subcarrier horizontal direction precoding matrix.

Step 502, the base station determines a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

wherein, W_(CA1)A precoding matrix, W, for the first subcarrier_(CA2)A precoding matrix, W, for the second subcarrier_(CA1，1)Precoding matrix for first subcarrier vertical direction, W_(CA1，2)A precoding matrix is horizontally arranged for the first subcarrier; w_(CA2，1)For the vertical precoding matrix, W, of the second subcarrier_(CA2，2)And precoding a matrix for the horizontal direction of the second subcarrier. Since the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction in a general scenario, the vertical direction is similar to a single-path channel, and the vertical direction channel can be determined to be a single-path channel model, and further, the PMI corresponding to the precoding matrix in the vertical direction under different subcarriers that the UE needs to feedback can be similar or equal to the PMI corresponding to the precoding matrix in the vertical direction under different subcarriers is equal, and corresponding to this embodiment, the PMI is used for indicating the first subcarrierWave vertical precoding matrix W_(CA1，1)PMI of_(CA1，1)And for indicating the second subcarrier vertical direction precoding matrix W_(CA2，1)PMI of_(CA2，1)Equal, i.e.:

PMI_(CA1，1)＝PMI_(CA2，1)＝PMI_C

in such a case, the base station may determine the PMI of the UE_CIs the at least one common PMI. Correspondingly, the base station may determine a precoding matrix W for indicating the horizontal direction of the first subcarrier_(CA1，2)PMI of_(CA1，2)Is the at least one first PMI; determining a precoding matrix W for indicating the horizontal direction of the second subcarrier_(CA2，2)PMI of_(CA2，2) Is the at least one second PMI. Based on the above condition, i.e. approximating a single path channel in the vertical direction, it can be guaranteed that the UE transmits the PMI at the reception_C、PMI_(CA1，2)、PMI_(CA2，2)According to the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). Enabling the base station to follow the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). The determination here may also be obtained by receiving an indication from the UE or other device or a negotiation determination of both.

According to the description of the above embodiments, when the precoding matrix of the first subcarrier can be decomposed into the vertical precoding matrix and the horizontal precoding matrix, the PMI indicates the vertical precoding matrix and the horizontal precoding matrix respectively, and by using the characteristic that the angular spread of the vertical beam is relatively small, the base station receives the PMI that each subcarrier can be used in common and the non-common PMI that cannot be used in common, which are sent by the UE, wherein in the process of determining two subcarrier precoding matrices at a time, the total number of the fed-back PMIs K to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs smaller than the number of Q, so as to achieve the purpose of saving channel resources. It should be understood that, if the angular spread of the horizontal directional beam of the antenna is much smaller than the angular spread of the vertical directional beam due to a change in the position, channel characteristics, or other conditions of the antenna, the horizontal directional channel may be determined as a model approximating a single-path channel, the PMI for indicating the horizontal directional precoding matrix of the first subcarrier may be determined as the at least one common PMI, the PMI for indicating the vertical directional precoding matrix of the first subcarrier may be determined as the at least one first PMI, and the PMI for indicating the vertical directional precoding matrix of the second subcarrier may be determined as the at least one second PMI. The specific steps and flow are the same as those in the above embodiments, and are not described herein again.

in another embodiment, another method for PMI feedback is introduced. The method may be, but is not limited to, an antenna scenario for 2d mimo. The precoding matrix of the first subcarrier is a first precoding matrix W of the first subcarrier₅And a second precoding matrix W₆The product of (a); the common PMI is the W₅PMI of (a) and the W₆One of the PMIs of (a); the first non-common PMI is the W₅PMI of (a) and the W₆Another one of the PMIs of (1); the precoding matrix of the second subcarrier is the first precoding matrix W of the first subcarrier₇And a second precoding matrix W₈The product of (a); the common PMI is the W₇PMI of (a) and the W₈One of the PMIs of (a); the first non-common PMI is the W₇PMI of (a) and the W₈Another one of the PMIs of (1). For example, the precoding matrix of the first subcarrier is a long-term wideband characteristic matrix (the W) of the first subcarrier₅) And short term narrow band characteristicsProperty matrix (the W)₆) The product of (a); the precoding matrix of the second subcarrier is a long-term wideband characteristic matrix (the W) of the second carrier₇) And a short-term narrow-band characteristic matrix (the W)₈) The product of (a);

Next, a specific embodiment is given, and this embodiment specifically provides a method for forming a codebook and a method for determining the codebook. For certain scenarios, the first subcarrier may be decomposed into the product of the W5 and the W6, and the second subcarrier may be decomposed into the W₇And said W₈Wherein, said W₅Representing long term/wideband characteristics of the first subcarrier precoding matrix; the W is₆Representing short-term/narrow-band characteristics of the first sub-carrier; the W is₇Representing long term/wideband characteristics of the second subcarrier precoding matrix; the W is₈Representing short-term/narrow-band characteristics of the second sub-carrier. Namely, the following conditions are satisfied:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

B＝[b₀，b₁，...b₃₁]

X^(k)＝[b_{2k mod 32}b_{(2k+1)mod 32}b_{(2k+2)mod 32}b_{(2k+3)mod 32}]

Where mod is the modulo symbol.

Further obtaining said W₅＝W₅ ^(k)：

According to the W₅ ^(k)Constructing codebook set C₁：

W₅ ^(k)The matrix characterizes the long-term wideband properties of the channel, on the other hand, another PMI (for convenience, this PMI is referred to as PMI₆) For indicating to the base station from codebook set C₁At least one element (codebook) and constructing the W₆. Constructing different codebook sets C for different RI₂. For example, when RI is 1, the codebook set may be configured as follows：

When RI is 2, the codebook set may be configured as follows:

Correspondingly, the formula:

W′_(CA1)＝W₅×W₆

W 'mentioned above'_(CA1)＝W₅×W₆And W'_(CA2)＝W₇×W₈Formally, it may be applied in particular in 2D MIMO scenarios, where the precoding matrix may specifically be represented by a product of the long-term wideband characteristic and the short-term narrowband characteristic of the signal. Fig. 6 shows the specific implementation steps when one precoding matrix can be shared due to its long-term wideband nature of the subcarriers.

Specifically, in step 601, the base station receives at least one common PMI, at least one first PMI and at least one second PMI; wherein the at least one common PMI is used to indicate that a long-term wideband characteristic matrix is embodied; the at least one first PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in a first subcarrier; the at least one second PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in the second subcarrier.

Step 602, the base station determines a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

For convenience of understanding, the present invention further provides a specific implementation manner for specifically determining the PMI by looking up a table, which can be used in a scenario where the precoding matrix is formed by multiplying the first subcarrier precoding matrix and the second subcarrier precoding matrix. It should be understood that the table lookup in the present invention may be a table stored in the UE or the base station, the table includes the corresponding relationship between the PMI and the matrix, and the table may be multiple in consideration of specific applications, so that the PMI and the specific precoding sub-matrix correspond to different tables under different RI values or other parameters. The base station acquires information required in the table; or an array or a relationship for querying the precoding matrix corresponding to the corresponding PMI value. It should be understood that the specific form of the table may be various, and may be a mapping relation or a functional relation stored in the UE or the base station, and the present invention is not limited thereto. For convenience of description, the present embodiment is described in a table form. The base station determines the long-term wideband matrix corresponding to the first subcarrier and the second subcarrier according to the PMI, and determines a corresponding table in the corresponding rank, for example, the value range of the rank indication is 1-4, then, it determines that the corresponding table is needed in tables 1 to 4 (table 1 corresponds to rank indication 1, table 2 corresponds to rank indication 2, table 3 corresponds to rank indication 3, and table 4 corresponds to rank indication 4):

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Determining one of tables 1-4 according to the RI, after the base station receives a common PMI (i1), a first PMI (i2) and a second PMI (i 2'), determining the common PMI (i) of the CA1 and the CA2 according to a specific use scenario in the determined table₁) The short-term narrowband characteristic matrix of CA1 and the short-term narrowband characteristic matrix of CA2 are determined according to the first PMI and the second PMI.

It should be understood that, in the case that there are multiple CAs, for example, CA1, CA2, and CA3, it may also receive a common PMI, and for example, the PMI corresponding to the short-term narrowband characteristic matrices of CA1, CA2, and CA3 may be used as a common PMI, and 1 time of common PMI feedback is fed back, which may indicate the short-term narrowband characteristic matrices in three carriers, and the base station receives the common PMI fed back by the UE, so as to achieve the purpose of further saving resources. Of course, the present embodiment is also applicable to the long-term wideband characteristic and the vertical and horizontal precoding matrices, and will not be described herein again. Of course, there may be multiple PMIs common to multiple CAs.

Fig. 6 illustrates an embodiment, according to the table, the long-term wideband characteristic matrix of the first subcarrier precoding matrix may be shared with other subcarriers, PMIs corresponding to different subcarriers may be used as a common PMI, the base station receives the common PMI once when determining two precoding matrices of different subcarriers, the base station receives a non-common PMI that cannot be commonly used by each subcarrier sent by the UE, so as to indicate 4 precoding matrices under 2 subcarriers (i.e., a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier and the second subcarrier, respectively), and the number k of received PMIs smaller than the number of all 4 precoding matrices that can be determined by the k PMIs, so as to achieve the purpose of saving channel resources. It should be understood that the long-term wideband characteristic matrix according to the first subcarrier precoding matrix in the table may be shared with other subcarriers, and in other scenarios, a situation that the short-term narrowband characteristic matrix may be shared with other subcarriers may also occur, which corresponds to the determination method in this embodiment and is not described herein again.

It should be understood that the embodiments of the present invention all determine precoding matrices under two subcarriers, and the present invention claims that when the number of subcarriers is more than two, there is a PMI that can be shared with other subcarriers in respective PMIs of the two subcarriers, and meanwhile, there may also be several subcarriers in a subcarrier that are different from PMIs fed back by any one of the at least two subcarriers, and PMIs corresponding to the several subcarriers adopt a form of separate feedback. For example, there are 3 subcarriers CA1, CA2, CA3, wherein although there are one or more common PMIs in CA1 and CA2, none of the PMIs of CA3 can be used as a common PMI with any PMIs of CA1 or CA2, then the base station will determine a precoding matrix according to feeding back all PMIs of CA3 separately.

Next, still another embodiment will be described with respect to a method of specifically determining a common PMI of the present invention. According to the embodiments shown in fig. 4-6, when a certain PMI of the first subcarrier is determined_aCertain PMI with a second subcarrier_bDifferent, but will PMI_aPMI used as second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the base station can directly determine that the common PMI is the PMI_a(ii) a Correspondingly, when PMI is to be transmitted_aPMI used for indicating second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the PMI can also be directly determined_aIs the common PMI; or when using a PMI_cWhen used as a common PMI for the first subcarrier and the second subcarrier, the PMI may be used_aAnd the PMI_bIn this case, when the channel characteristics of the system can satisfy a certain condition, the PMI may be directly determined_cAs the at least one common PMI. The above procedure may be determined at the UE or the base station. Optionally, the base station may determine the at least one common PMI, the at least one first PMI, the at least one second PMI, and a compensation value δ, where the at least one common PMI and the at least one first PMI are used to determine a precoding matrix of a first subcarrier; the at least one common PMI, the at least one second PMI and the delta jointly indicate a precoding matrix of a second subcarrier, and the base station receives the at least one common PMI, the at least one common PMI and the delta sent by the UEAt least one first PMI, the at least one second PMI, one compensation value δ. It should be understood that the PMI of the second subcarrier may also be determined as the at least one common PMI, a compensation value δ 'is received, and a precoding matrix of the first subcarrier is determined according to the at least one common PMI, the δ', and the at least one first PMI; determining a precoding matrix of the second subcarrier according to the at least one common PMI and the second PMI. In general, the number of bits or resources occupied by δ may be, but is not limited to, less than the number of bits or resources occupied by one PMI. In this case, the purpose of indicating the precoding matrix of two subcarriers more accurately can be achieved while saving resources.

Optionally, the base station receives the first PMI compensation value δ₁And/or a second PMI compensation value delta₂Said delta₁A precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the₂A precoding matrix for co-determining the second subcarrier with the at least one common PMI and the at least one second PMI.

The base station determines or receives a first PMI compensation value delta₁And/or a second PMI compensation value delta₂There are three cases:

case 1:

the base station or UE determines the delta₁And delta₂Said base station receiving said delta₁And delta₂；

Case 2:

the base station or UE determines the delta₁Said base station receiving said delta₁；

Case 3:

the base station or UE determines the delta₂Said base station receiving said delta₂。

It is to be understood that δ₁And delta₂The order of the PMIs to be received by the base station is not limited, and the PMIs may be received simultaneously or sequentially. According to different scenes corresponding to the public PMI, the invention provides three specific practicesThe implementation mode is as follows:

embodiment 7:

Embodiment 8:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

Embodiment 9:

according to the above embodiment, two compensation values, δ, can also be given simultaneously_cAnd delta_d. In this case, the δ_cA precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the_dFor co-sharing with the at least one common PMI, the at least one second PMIAnd determining a precoding matrix of the second subcarrier.

It should be understood that, the above-mentioned various embodiments for determining the compensation value give a basis or an order of determination, the specific determination method is not limited by the present invention, and the determination manner of the compensation value may be different according to the allocated bit number, for example, when the common PMI is used to indicate that the error of the first subcarrier precoding matrix and the second subcarrier precoding matrix is not large (i.e. can be within a tolerance range), 1 bit may be allocated, 0 represents no compensation, 1 represents compensation, and the specific compensation value may be predefined; in one embodiment, PMI_XAnd PMI_YFor indicating a first subcarrier precoding matrix, PMI_ZAnd PMI_WFor indicating the second subcarrier precoding matrix. Indicating PMI when it is determined that common PMI can be simultaneous PMI_XAnd PMI_ZI.e. common PMI and PMI_Y(PMI here)_YEquivalent to the first PMI) indicates a precoding matrix of a first subcarrier; common PMI and PMI_Z(PMI here)_WEquivalent to the second PMI) indicates a precoding matrix of a second subcarrier; when determining PMI_XWhen the PMI is equal to 7, the PMI may be identical to the first PMI (may be a PMI in this embodiment)_Y) Jointly indicate the first subcarrier precoding matrix if PMI_WCorresponding characteristics and PMI_XIs not very different or the same, i.e., PMI can be determined_WWhen δ is received by the base station, it can be determined that compensation is not needed as long as δ is 0; however, if the system determines to use PMI_W10 and the second PMI (which may be a PMI in this embodiment)_W) When the second subcarrier precoding matrix is indicated jointly to be accurate, then using the common PMI of 7 and the second PMI to indicate the second subcarrier precoding matrix jointly may bring about a relatively large error, where the system may be the base station, the UE, or another network device notifying the base station. However, if the system preset offset value δ is 1 for offset 3, then 1 bit can be accurateAnd the ground indicates that the base station or the UE side needs to compensate 3 again by using the common PMI of 7, and then the common PMI and the second PMI jointly determine a second subcarrier precoding matrix. It should be understood that, for this example, in some scenarios, if the compensation value δ of the system preset is 1 to represent the compensation 2, the value indicated jointly by the common PMI and the compensation value is 9, which is also acceptable if within some tolerable range.

It should be understood that the above-described method of determining or receiving the compensation value is merely an example, and that the determination or reception of the compensation value may be combined with any of the embodiments of transmitting the compensation value, and other embodiments of the present invention, within the scope of logic.

By utilizing the single-path characteristic in the vertical direction of different subcarriers or the similarity of the long-term broadband characteristics of different subcarriers, a vertical direction precoding matrix or a long-term broadband characteristic precoding matrix of a certain subcarrier can be received as the common PMI under different channel models, and then a compensation value delta is received; and determining a vertical direction precoding matrix or a long-term broadband characteristic precoding matrix of another subcarrier according to the delta and the common PMI. And determining the precoding matrixes under different subcarriers according to the first PMI and the second PMI, thereby saving channel resources and improving the indication precision.

Fig. 7 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. To a user equipment, UE, for feedback of precoding matrix indicator, PMI, for a wireless communication system with multi-carrier capability, the UE communicating with a base station using a first subcarrier and a second subcarrier. The method specifically comprises the following steps:

a determining unit 701, configured to determine at least one common PMI, at least one first PMI and at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; wherein the common PMI, the first PMI and the second PMI may be 2, 3 or more than 3, respectively. The specific function in step 101 can be realized.

It should be understood that the present invention is not limited to the specific way in which the determining unit determines the PMI, and the process of determining the PMI by the determining unit may be determined according to reference signal measurement, or may be a process of traversing from pre-coding submatrices of different dimensions respectively according to measurement reference signals to select a matrix with the optimal signal quality. The measurement process may be a process of receiving the reference signal by a receiving unit 703, and the measurement unit is configured to measure the reference signal, and the measurement unit may also be integrated in the determination unit.

In a specific embodiment, a specific example may be made with reference to the step of determining at least one common PMI, at least one first PMI and at least one second PMI in step 101.

The specific order of determining the at least one common PMI, the at least one first PMI and the at least one second PMI by the determining unit may be different, and reference may be made to specific implementation mode 1, implementation mode 2 and implementation mode 3 in the embodiment shown in fig. 1, it should be understood that the present invention is not limited to the specific implementation steps given in the above implementation modes 1 to 3, and may also be other specific implementations for determining the at least one common PMI. Reference may be made to fig. 1 for an embodiment, where different RIs correspond to different PMI table determination manners one by one.

It should be understood that the present invention is not limited to the determination process of each PMI, and may be, but not limited to, the result of negotiation between the UE and the base station, or a rule predetermined by both parties, or directly determined by the UE, or receiving a notification from the base station through the receiving unit, or determining a specific determination mode according to an application scenario.

A transmitting unit 702, configured to transmit the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system. The specific functions in step 102 may be implemented.

The UE apparatus fed back by the PMI described in this embodiment may integrate respective PMIs corresponding to different subcarriers by using the same PMIs in some items among different subcarriers in different scenarios, so that the UE only feeds back a common PMI once in a process of determining a precoding matrix, where the common PMI is used to indicate precoding matrices of different subcarriers, and the base station determines the precoding matrices of each subcarrier respectively through the common PMI and non-common PMIs (in this embodiment, the first PMI and the second PMI) under each different subcarrier. In this embodiment, the sending unit of the UE sends, to the base station, a PMI that can be used by each subcarrier in a common manner and a non-common PMI that cannot be used by the subcarrier in a common manner, where in a process of determining two subcarrier precoding matrices at a time, a total number of fed-back PMIs K to indicate Q precoding matrices under two subcarriers, and the number K of fed-back PMIs less than the number of Q, so as to achieve a purpose of saving channel resources. It should be understood that, in all embodiments of the present invention, the common PMI, the first PMI and the second PMI do not necessarily exist independently, and different fields of the same message may be referred to as the common PMI, the first PMI and the second PMI.

It should be understood that, for different scenarios, the determining unit may determine the common PMI and the non-common PMI according to specific scenario characteristics, so as to achieve the purpose of saving channel resources. The following will specifically describe a UE apparatus for feeding back a precoding matrix indicator PMI shown in fig. 7 in different scenarios:

fig. 8 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. The precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

The method specifically comprises the following steps:

a determining unit 801, configured to determine at least one common PMI, at least one first PMI, and at least one second PMI, where the at least one common PMI is used to indicate a vertical direction precoding matrix; the at least one first PMI is used for indicating a first subcarrier horizontal direction precoding matrix; the at least one second PMI is used for indicating a second subcarrier horizontal direction precoding matrix.

A sending unit 802, configured to send, to a base station, the at least one common PMI, the at least one first PMI, and the at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier, and the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

wherein, W_(CA1)A precoding matrix, W, for the first subcarrier_(CA2)A precoding matrix, W, for the second subcarrier_(CA1，1)Precoding matrix for first subcarrier vertical direction, W_(CA1，2)Is the first sub-carrierA horizontal direction precoding matrix; w_(CA2，1)For the vertical precoding matrix, W, of the second subcarrier_(CA2，2)And precoding a matrix for the horizontal direction of the second subcarrier. In a general scenario, the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction, so the vertical direction is similar to a single-path channel, the determining unit may determine that the vertical direction channel is a single-path channel model, and further, may be similar or equal to that PMIs corresponding to precoding matrices in the vertical direction under different subcarriers that the UE needs to feed back are equal, and corresponding to this embodiment, the determining unit is configured to indicate the precoding matrix W in the vertical direction of the first subcarrier_(CA1，1)PMI of_(CA1，1)And for indicating the second subcarrier vertical direction precoding matrix W_(CA2，1)PMI of_(CA2，1)Equal, i.e.:

PMI_(CA1，1)＝PMI_(CA2，1)＝PMI_C

in this case, the determination unit may determine the PMI_CIs the at least one common PMI. Correspondingly, the determining unit determines a precoding matrix W for indicating the horizontal direction of the first subcarrier_(CA1，2)PMI of_(CA1，2)Is the at least one first PMI; the determination unit determines a precoding matrix W indicating the horizontal direction of the second subcarrier_(CA2，2)PMI of_(CA2，2)Is the at least one second PMI. Based on the above condition, i.e. approximating a single path channel in the vertical direction, it can be guaranteed that a PMI is being transmitted_C、PMI_(CA1，2)、PMI_(CA2，2)According to the PMI_CAnd PMI_(CA1，2)Indicates the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Indicates the W_(CA2，2). Enabling the base station to follow the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). The determination process here may be determined by negotiation of the base station, or may be notified to the base station after receiving an indication from the base station or other devices or determining itself.

According to the description of the above embodiments, when the precoding matrix of the first subcarrier can be decomposed into the vertical precoding matrix and the horizontal precoding matrix, the PMI indicates the vertical precoding matrix and the horizontal precoding matrix respectively, and the transmitting unit transmits, to the base station, the PMI that each subcarrier can be commonly used and the non-common PMI that cannot be commonly used by using the characteristic that the angular spread of the vertical beam of the PMI is relatively small, wherein, in the process of determining two subcarrier precoding matrices at a time, the total number of the fed-back PMIs K to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs smaller than the number of Q, so as to achieve the purpose of saving channel resources. It should be understood that, if the angular spread of the horizontal directional beam of the antenna is much smaller than the angular spread of the vertical directional beam due to a change in the position, channel characteristics, or other conditions of the antenna, the horizontal directional channel may be determined to be a model approximating a single-path channel, and the determining unit may determine the PMI for indicating the horizontal directional precoding matrix of the first subcarrier to be the at least one common PMI, the PMI for indicating the vertical directional precoding matrix of the first subcarrier to be the at least one first PMI, and the PMI for indicating the vertical directional precoding matrix of the second subcarrier to be the at least one second PMI. The specific steps and flow are the same as those in the above embodiments, and are not described herein again.

It should be understood that the judgment about the channel model may be a condition determined by the determining unit by reaching a certain condition, and may be directly configured or calculated and determined according to the base station or the UE.

In an embodiment, when the difference between PMIs in some entries of different subcarriers is smaller than a certain threshold in some cases, the determining unit may also determine such a PMI as a common PMI. It should be understood that the present invention does not limit the number of subcarriers, and as long as at least one PMI of each of a plurality of subcarriers can be determined as the common PMI according to a preset rule or a certain condition, the number of PMI feedbacks can be reduced, thereby achieving the purpose of saving channel resources.

in another embodiment, an apparatus for feeding back another PMI is presented. The apparatus may be, but is not limited to, an antenna scenario for 2d mimo: the precoding matrix of the first subcarrier is a first precoding matrix W of the first subcarrier₅And a second precoding matrix W₆The product of (a); the common PMI is the W₅PMI of (a) and the W₆One of the PMIs of (a); the first non-common PMI is the W₅PMI of (a) and the W₆Another one of the PMIs of (1); the precoding matrix of the second subcarrier is the first precoding matrix W of the first subcarrier₇And a second precoding matrix W₈The product of (a); the common PMI is the W₇PMI of (a) and the W₈One of the PMIs of (a); the first non-common PMI is the W₇PMI of (a) and the W₈Another one of the PMIs of (1). For example,the precoding matrix of the first subcarrier is a long-term wideband characteristic matrix (the W) of the first subcarrier₅) And a short-term narrow-band characteristic matrix (the W)₆) The product of (a); the precoding matrix of the second subcarrier is a long-term wideband characteristic matrix (the W) of the second carrier₇) And a short-term narrow-band characteristic matrix (the W)₈) The product of (a);

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

wherein, W'_(CA1)A precoding matrix for the first subcarrier; w'_(CA2)A precoding matrix for the second subcarrier; next, first, W 'is given'_(CA1)And said W₅PMI (PMI) of response₅) And said W₆Corresponding PMI (PMI)₆) Of (c), corresponding to, W'_(CA2)And said W₇Corresponding PMI₇And said W₈Corresponding PMI₈Is onMay be the same. If codebook set B is:

B＝[b₀，b₁，...b₃₁]

X^(k)＝[b_{2k mod 32}b_{(2k+1)mod 32}b_{(2k+2)mod 32}b_{(2k+3)mod 32}]

Where mod is the modulo symbol.

Further obtaining said W₅＝W₅ ^(k)：

According to the W₅ ^(k)Constructing codebook set C₁：

When RI is 2, the codebook set may be configured as follows:

Correspondingly, the formula:

W′_(CA1)＝W₅×W₆

can represent a selection matrix W₆From W₅The superposition of some columns is selected to form a precoding matrix corresponding to the first subcarrier. W is as described above₅ ^(k)A matrix comprising 4 beams, representing long term wideband channel characteristics, may be shared by a first subcarrier and a second subcarrier and, therefore, may be available for different subcarriersTo share one W₅And each subcarrier can independently feed back a matrix W embodying short-term narrow-band characteristics₆Corresponding PMI₆And a matrix W embodying short-term narrow-band characteristics₈Corresponding PMI₈. It should be understood that the specific values in the above example are only one example given for the sake of convenience, and may be varied by the antenna port, rank indication, or other parameters during the specific application. And the codebook and the selection manner are exemplary descriptions, and the invention claims codebooks and manners of selecting codebooks in other forms.

A determining unit 901, configured to determine at least one common PMI, at least one first PMI, and at least one second PMI, where the at least one common PMI is used to indicate that a long-term wideband characteristic matrix is embodied; the at least one first PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in a first subcarrier; the at least one second PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in the second subcarrier.

A sending unit 902, configured to send, to a base station, the at least one common PMI, the at least one first PMI, and the at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier, and the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

It should be understood that the present invention does not limit mutual integration among the various embodiments, and the specific determining unit determines the order and the specific determining manner of the PMI, and the embodiments in fig. 8 and 9 can be implemented as in the embodiments 1 to 3 shown in fig. 1, and are not described herein again.

For convenience of understanding, the present invention further provides a specific implementation manner in which the determining unit specifically determines the PMI by looking up a table, and the implementation manner can be used in a scenario in which the precoding matrix is formed by multiplying the first subcarrier precoding matrix and the second subcarrier precoding matrix. It should be understood that the table lookup in the present invention may be a table stored in the UE or the base station, the table includes the corresponding relationship between the PMI and the matrix, and the table may be multiple in consideration of specific applications, so that the PMI and the specific precoding sub-matrix correspond to different tables under different RI values or other parameters. The determining unit acquires information required in a table; or an array or a relationship for querying the PMI value corresponding to the corresponding precoding matrix. It should be understood that the specific form of the table may be various, and may be a mapping relation or a functional relation stored in the UE or the base station, and the present invention is not limited thereto. For convenience of description, the present embodiment is described in a table form. The determining unit determines the long-term wideband matrix corresponding to the first subcarrier and the second subcarrier, and determines the corresponding table in the corresponding rank, for example, the value range of the rank indication is 1-4, then the determining unit determines that the corresponding table is needed in tables 1 to 4 (table 1 corresponds to rank indication 1, table 2 corresponds to rank indication 2, table 3 corresponds to rank indication 3, table 4 corresponds to rank indication 4):

TABLE 1

TABLE 2

TABLE 3

TABLE 4

The determining unit determines one of tables 1 to 4 according to the RI, determines long-term wideband characteristic matrices of the CA1 and the CA2 according to specific usage scenarios in the determined table, and further determines the common PMI (i) according to the long-term wideband characteristic matrices₁) According to the short-term narrow-band characteristic matrix of CA1 and the PMI corresponding to the short-term narrow-band characteristic matrix of CA2, respectively determining the first PMI (i) corresponding to CA1₂) And the second PMI (i) corresponding to the CA2₂') to transmit the values of i1, i2, i 2' to the base station.

The determining unit determines the common PMI (i) of the CA1 and the CA2 in the determined table₁) The specific manner of the value of (i) can be determined according to the channel characteristics, and in tables 1 to 4, PMI (i)₁)，PMI(i₂) For determining

In addition to using the PMI corresponding to the short-term narrowband characteristic matrix as the common PMI, the determining unit may confirm the PMI value of the long-term wideband characteristic matrix corresponding to CA1 and the PMI value of the long-term wideband characteristic matrix corresponding to CA2, respectively, and select one of the PMI values as the common PMI. It should be understood that, in the case of multiple CAs, for example, CA1, CA2, and CA3, it may also determine a common PMI, and for example, the PMI corresponding to the short-term narrowband characteristic matrix of CA1, CA2, and CA3 may be used as the common PMI, and the UE may only feed back 1 time of the common PMI, and may indicate the short-term narrowband characteristic matrix in three carriers, so as to achieve the purpose of further saving resources. Of course, the present embodiment is also applicable to the long-term wideband characteristic and the vertical and horizontal precoding matrices, and will not be described herein again. Of course, there may be multiple PMIs common to multiple CAs.

Fig. 9 shows an embodiment, the determining unit may share the long-term wideband characteristic matrix of the first subcarrier precoding matrix with other subcarriers according to the table, the PMI corresponding to different subcarriers may be used as a common PMI, and when the determining unit determines two precoding matrices of different subcarriers, the transmitting unit transmits the common PMI to the base station once, the transmitting unit transmits, to the base station, a non-common PMI that cannot be commonly used by each subcarrier, so as to indicate 4 precoding matrices of 2 subcarriers (that is, a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier and the second subcarrier, respectively), and the number k of PMIs fed back is smaller than the number of all 4 precoding matrices that can be determined by the k PMIs, so as to achieve the purpose of saving channel resources. It should be understood that the long-term wideband characteristic matrix according to the first subcarrier precoding matrix in the table may be shared with other subcarriers, and in other scenarios, a situation that the short-term narrowband characteristic matrix may be shared with other subcarriers may also occur, which corresponds to the determination method in this embodiment and is not described herein again.

It should be understood that, in the embodiments of the present invention, the determining unit determines PMIs under two subcarriers, and the present invention claims that, when the number of subcarriers is more than two, there is a PMI that can be shared with other subcarriers in the PMIs of the two subcarriers, and meanwhile, there may also be several subcarriers in the subcarriers that are different from PMIs fed back by any one of the at least two subcarriers, and the sending unit sends PMIs corresponding to the several subcarriers in a form of separate feedback. For example, there are 3 subcarriers CA1, CA2, CA3, wherein although there are one or more common PMIs for CA1 and CA2, the UE cannot determine any one PMI for CA3 and any one PMI for CA2 and CA1 as a common PMI, and then the UE will feed back all PMIs for CA3 alone.

Next, still another embodiment will be described with respect to a method of specifically determining a common PMI of the present invention. According to the embodiments shown in fig. 7-9, when the determining unit determines a PMI of the first subcarrier_aCertain PMI with a second subcarrier_bDifferent, but will PMI_aPMI used as second subcarrier_bThe determining unit may directly determine the PMI when the channel characteristic of the system is within a certain tolerance range or meets a certain condition_aIs the common PMI; correspondingly, when PMI is to be transmitted_aPMI used for indicating second subcarrier_bThe determining unit may directly determine the PMI when the channel characteristics of the system are within a certain tolerance range or satisfy a certain condition_aIs the common PMI; or when using a PMI_cWhen used as a common PMI for the first subcarrier and the second subcarrier, the PMI may be used_aAnd the PMI_bIn this case, the determining unit may directly determine the PMI when the channel characteristics of the system can satisfy a certain condition_cAs the at least one common PMI. Optionally, the determining unit may determine the at least one common PMI, the at least one first PMI, the at least one second PMI, and a compensation value δ, where the at least one common PMI and the at least one first PMI are used to determine a precoding matrix of a first subcarrier; the at least one common PMI, the at least one second PMI, and the δ collectively indicate a precoding matrix of a second subcarrier, and the transmitting unit transmits the at least one common PMI, the at least one first PMI, the at least one second PMI, and a compensation value δ to the base station. It should be understood that the determining unit may also determine the PMI of the second subcarrier as the at least one common PMI, and the transmitting unit is further configured to transmit a compensation value δ 'so as to determine the precoding matrix of the first subcarrier according to the at least one common PMI, the δ', and the at least one first PMI; determining a precoding matrix of the second subcarrier according to the at least one common PMI and the second PMI. Generally, the number of bits or resources occupied by δ is smaller than that occupied by one PMIThe number of bits or the number of resources. In this case, the purpose of indicating the precoding matrix of two subcarriers more accurately can be achieved while saving resources.

Optionally, the determining unit determines and sends the first PMI compensation value δ₁And/or a second PMI compensation value delta₂Said delta₁A precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the₂A precoding matrix for co-determining the second subcarrier with the at least one common PMI and the at least one second PMI.

The determining unit determines and transmits the first PMI compensation value δ₁And/or a second PMI compensation value delta₂Three cases can be distinguished:

case 1:

the determination unit is used for determining the delta₁And delta₂The transmitting unit is used for transmitting the delta to the base station₁And delta₂；

Case 2:

the determination unit is used for determining the delta₁The transmitting unit is used for transmitting the delta to the base station₁；

Case 3:

the determination unit is used for determining the delta₂The transmitting unit is used for transmitting the delta to the base station₂。

It is to be understood that δ₁And delta₂The order of the PMIs to be fed back to the UE is not limited, and may be transmitted simultaneously or sequentially. According to different scenes corresponding to the public PMI, the invention provides three specific implementation modes:

embodiment 10:

since the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction, the vertical direction approximates to a single-path channel, and the determining unit may determine that the vertical direction channel approximates to a single-path channel model, as an example, in embodiment 4, the determining unit determines W_(CA1，1)Corresponding PMI_(CA1，1)The determination unit determines the PMI as one common PMI_(CA1，1)And said W_(CA2，1)Corresponding PMI_(CA2，1)May be represented by delta_aAnd (4) determining. The determination unit determines W_(CA1，2)Corresponding PMI_(CA1，2)Determining W for the first PMI, the determination unit_(CA2，2)Corresponding PMI_(CA2，2)As the second PMI, here, the common PMI and the first PMI are used to determine (indicate) W, respectively_(CA1，1)And said W_(CA1，2)The common PMI, the delta_aDetermining the W_(CA2，1)Said second PMI said W_(CA2，2)To identify the first subcarrier precoding matrix W_(CA1)、W_(CA2). It should be understood that the determination unit determines the PMI_(CA2，1)As the common PMI, δ is correspondingly used_a' and the common PMI indicate the W_(CA1)The method can be the same as the above method, and is not described again.

Embodiment 11:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

the matrix W5 representing the long-term wideband channel characteristics of CA1 may be implemented as PMI₅Indication, the matrix W7 representing the long-term wideband channel characteristics of CA2 may be PMI₅And a compensation value delta_bIndicating that, as an example, the determining unit is configured to determine a PMI (PMI) corresponding to W5₅) As the common PMI, a PMI (PMI) corresponding to W6₆) The determining unit is configured to determine, for the first PMI, a PMI (PMI) corresponding to the W8₈) For the second PMI, in one embodiment, the common PMI is used to indicate the W5, the first PMI is used to indicate the W6, and the second PMI is used to indicate the W8, the common PMI, and the δ_bFor indicating the W7, the W5, W6 for determining the W'_(CA1)The W7, the W8 are used to determine the W'_(CA2)(ii) a In another embodiment, the determining unit is configured to determine the corresponding table in tables 1-4, i in the common PMI corresponding table according to rank indication₁I in the first PMI correspondence table₂Determining a precoding matrix W corresponding to the first subcarrier; the common PMI and the delta_b' value obtained after calculation corresponds to i in table₁I in the second PMI correspondence table₂Determining a precoding matrix W corresponding to the second subcarrier₂. It should be understood that the method for determining the PMI7 as the common PMI is the same as the above embodiments, and is not described again.

Embodiment 12:

according to the above embodiment, two compensation values, δ, can also be given simultaneously_cAnd delta_d. In this case, the δ_cA precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the_dA precoding matrix for co-determining the second subcarrier with the at least one common PMI and the at least one second PMI.

It should be understood that when reference is made to the case of compensation of a compensation value, it may be provided that the compensation value is not compensated for at a certain time of feedback. The signaling may be sent by a sending unit, or a receiving unit for receiving the signaling, or other modes that agree not to employ compensation.

It should be understood that, the above embodiments regarding the determining unit determining the compensation value have given references or orders determined by the determining unit, and the specific determining method of the present invention is not limited, and the determining manner of the compensation value may be different according to the allocated bit number, for example, when the common PMI is used to indicate that the error of the first subcarrier precoding matrix and the second subcarrier precoding matrix is not large (i.e. can be within a tolerance range), 1 bit may be allocated, 0 represents no compensation, 1 represents compensation, and a specific compensation value may be predefined; in one embodiment, PMI_XAnd PMI_YFor indicating a first subcarrier precoding matrix, PMI_ZAnd PMI_WFor indicating the second subcarrier precoding matrix. When the determination unit determines that the common PMI may be a simultaneous indication PMI_XAnd PMI_ZI.e. common PMI and PMI_Y(PMI here)_YEquivalent to the first PMI) indicates a precoding matrix of a first subcarrier; using common PMI and PMI_Z(PMI here)_WEquivalent to the second PMI) indicates a precoding matrix of a second subcarrier; when determining PMI_XWhen the PMI is equal to 7, the PMI may be identical to the first PMI (may be a PMI in this embodiment)_Y) Jointly indicate the first subcarrier precoding matrix if PMI_WCorresponding characteristics and PMI_XIs not very different or the same, i.e., PMI can be determined_WAt this time, as long as the determination unit determines δ to be 0 and transmits δ, it can be notified that compensation is not required; however, if the determining unit or system determines to use the PMI_W10 and the second PMI (which may be a PMI in this embodiment)_W) When the second subcarrier precoding matrix is indicated together, then, using the common PMI of 7 and the second PMI to indicate the second subcarrier precoding matrix together may bring about a relatively large error. However, if the offset value δ preset by the determining unit or system is 1 for offset 3, then 1 bit can accurately indicate that the base station side needs to compensate 3 again with common PMI7, and then determine the second subcarrier precoding moment together with the second PMIAnd (5) arraying. It should be understood that, for this example, in some scenarios, if the compensation value δ preset by the determining unit or system is 1 to represent compensation 2, the value indicated jointly by the common PMI and the compensation value is 9, which may be acceptable within some tolerance range.

It should be understood that the above-mentioned determining unit determines the compensation value, and the method of the transmitting unit transmitting the compensation value is only an example, and the determination of the compensation value may be combined with any one of the embodiments of transmitting the compensation value, and other embodiments of the present invention, within a logical scope.

By using the single-path characteristics in the vertical direction of different subcarriers or the long-term broadband characteristics of different subcarriers are similar, under different channel models, the determining unit can determine the vertical direction precoding matrix or the long-term broadband characteristic precoding matrix of a certain subcarrier as the common PMI, and then determine a compensation value δ; indicating a vertical direction precoding matrix or a long-term wideband characteristic precoding matrix of another subcarrier according to the delta and the common PMI. According to the first PMI and the second PMI, the sending unit indicates the precoding matrixes under different subcarriers, so that channel resources are saved, and indication precision is improved.

Fig. 10 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. To a base station for feedback of precoding matrix indicator, PMI, for use in a multi-carrier capable wireless communication system, the base station communicating with the UE using a first subcarrier and a second subcarrier. The method specifically comprises the following steps:

the method specifically comprises the following steps:

a receiving unit 1001 configured to receive at least one common PMI, at least one first PMI, and at least one second PMI;

a determining unit 1002, configured to determine a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI, and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

Hereinafter, the step of determining at least one common PMI, at least one first PMI and at least one second PMI by the determining unit will be specifically described in an exemplary manner. For example, for the first subcarrier CA1, the determining unit needs to determine 4 PMIs to be PMI1/2/3/4, respectively, where the 4 PMIs are used to indicate the precoding matrix of the CA 1; for the second subcarrier CA2, the determining unit needs to determine 4 PMIs to be PMI5/6/7/8 respectively, and these 4 PMIs are used to indicate the precoding matrix of this CA 2. In one embodiment, the PMI1 and PMI2 may collectively indicate one sub-precoding matrix W under the CA1_A1(ii) a PMI3, PMI4 may indicate another sub-precoding matrix W under CA1_B1The determining unit then determines from the W_A1、W_B1Determining CA1 precoding matrix W according to the determined operational relationship_A1B1. PMI5 and PMI6 may jointly indicate one sub-precoding matrix W under CA2_A2(ii) a PMI7, PMI8 may indicate another sub-precoding matrix W under CA2_B2Then from the W_A2、W_B2Determining CA1 precoding matrix W according to the determined operational relationship_A2B2. The specific determination method may be different, and the present invention is not limited thereto, and may be determined in a form of calculating parameters of a precoding matrix, for example, the UE and/or the determining unit may calculate W according to two parameters of PMI1 and PMI2_A1Or the UE and/or the determining unit may store or determine a table in advance, and the determining unit may query the corresponding W according to PMI1 or PMI2_A1Alternatively, the PMI1/2/3/4 may be 4 parameters, the PMI5/6/7/8 may be 4 parameters, and the determining units directly calculate precoding matrices, respectively. It should be understood that the need to feed back 4 PMIs in the above one carrier is only an example, and in actual situations, other situations may occur. Each embodiment of the present application does not specify 4 PMIs. At least one PMI in the CA1 is the same as or similar to at least one PMI in the CA2 according to a certain channel condition or channel model. Then the at least one PMI of CA1 and the at least one PMI of CA2 may be determined as the common PMIPMI. Wherein, approximating here means that it can be equivalent, for example, even if two PMIs are different, the difference between the two PMIs is small, and finally the base station is within a tolerable range according to the respective calculated channel models of the precoding matrix of CA1 and the precoding matrix of CA 2. For example, PMI1 corresponds to PMI5, and may be determined as a common PMI if certain conditions are satisfied_C1(ii) a PMI3 corresponds to PMI7 and can be determined as common PMI_C2Namely:

PMI₁＝PMI₅＝PMI_C1

PMI₃＝PMI₇＝PMI_C2

then, referring to step 401, the receiving unit may receive a common PMI: PMI_C1、PMI_C2(ii) a And a first PMI: PMI2, PMI 4; a second PMI: PMI6, PMI 8. The method for determining the common PMI is usually determined by channel characteristics, for example, PMI1 and PMI5 are used to indicate that certain matrix parameters have high correlation in certain scenarios (such as high-rise scenarios or wide-area scenarios), and the values of the parameters are equal or the difference is negligible; or PMI1 and PMI5 indicate a matrix set composed of matrices of the same class in a table in some scenarios, and other PMI2/PMI6 further indicates a matrix (which is an element in the matrix set) in the matrix set, so that PMI1 and PMI5 can be determined as a common PMI in many same scenarios₁(ii) a Similarly, the PMI3 and PMI7 may also be indicated as described above. Or the base station side may directly predetermine the PMI_C1、PMI_C2Is a common PMI, and_C1stands for PMI1/PMI5, PMI_C2Representing PMI3/PMI7 and sent to the UE.

The determining unit may preset a rule, or determine the common PMI, the first PMI, and the second PMI in a manner of negotiating with the UE or other network devices through a transmitting unit or a receiving unit, or the receiving unit may directly indicate the common PMI, the first PMI, and the second PMI in a signaling or other signaling for receiving a feedback PMI, and the determining unit determines the precoding matrix according to the indication. E.g. determining the PMI in a high-rise scenario₁And PMI₅Determined as a common PMI, this preset rule is also in the UE interacting with it. The indication process may also come from other UEs or other network side devices.

It should be understood that, in step 402, the specific process of determining, by the determining unit, the precoding matrix of the first subcarrier and the precoding matrix of the second subcarrier according to the at least one common PMI, the at least one first PMI and the at least one second PMI may be different PMI tables corresponding to different RIs one to one, after the determining unit determines the value of the RI, the determining unit determines, from the plurality of PMI tables, a PMI table corresponding to the value of the RI, where the PMI table may include a corresponding relationship between a PMI and a precoding matrix and/or a corresponding relationship between a PMI and a precoding submatrix. The determining unit determines a precoding matrix of CA1 according to the common PMI and the first PMI, or determines a precoding matrix corresponding to CA2 according to the common PMI and the second PMI. The PMI table may be a specific table or a plurality of corresponding relationship sets stored in a memory.

By the PMI receiving and determining method described in this embodiment, it may be utilized that in different scenarios, PMIs in some items between different subcarriers are the same, and respective PMIs corresponding to different subcarriers are integrated, so that the receiving unit receives a common PMI only once in a process of determining a precoding matrix, where the common PMI is used to indicate precoding matrices of different subcarriers, and the determining unit determines the precoding matrices of each subcarrier respectively through the common PMI and non-common PMIs (in this embodiment, a first PMI and a second PMI) under each different subcarrier. In this embodiment, the receiving unit receives a PMI that can be commonly used by each subcarrier and a non-common PMI that cannot be commonly used, where in a process of determining two subcarrier precoding matrices by the determining unit at a time, a total number of the PMIs received by the receiving unit is K to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs less than the number of Q, so as to achieve a purpose of saving channel resources. It should be understood that the common PMI, the first PMI and the second PMI do not necessarily exist independently in the present invention, and may be referred to as the common PMI, the first PMI and the second PMI in different fields of the same message.

Fig. 11 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. To a base station for feedback of precoding matrix indicator, PMI, for use in a multi-carrier capable wireless communication system, the base station communicating with a UE using a first subcarrier and a second subcarrier. The precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier; the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier; the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier; the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

The method specifically comprises the following steps:

a receiving unit 1101, configured to receive at least one common PMI, at least one first PMI, and at least one second PMI, where the at least one common PMI is used to indicate a vertical direction precoding matrix; the at least one first PMI is used for indicating a first subcarrier horizontal direction precoding matrix; the at least one second PMI is used for indicating a second subcarrier horizontal direction precoding matrix.

A determining unit 1102, configured to determine a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI, and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

wherein, W_(CA1)A precoding matrix, W, for the first subcarrier_(CA2)A precoding matrix, W, for the second subcarrier_(CA1，1)Precoding matrix for first subcarrier vertical direction, W_(CA1，2)A precoding matrix is horizontally arranged for the first subcarrier; w_(CA2，1)For the vertical precoding matrix, W, of the second subcarrier_(CA2，2)And precoding a matrix for the horizontal direction of the second subcarrier. In a general scenario, the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction, so the vertical direction is similar to a single-path channel, the determining unit may determine that the vertical direction channel is a single-path channel model, and further, may be similar or equal to that PMIs corresponding to precoding matrices in the vertical direction under different subcarriers that the UE needs to feed back are equal, and corresponding to this embodiment, the determining unit is configured to indicate the precoding matrix W in the vertical direction of the first subcarrier_(CA1，1)PMI of_(CA1，1)And for indicating the second subcarrier vertical direction precoding matrix W_(CA2，1)PMI of_(CA2，1)Equal, i.e.:

PMI_(CA1，1)＝PMI_(CA2，1)＝PMI_C

in this case, the determining unit may determine the PMI of the UE_CIs the at least one common PMI. Correspondingly, the determining unit may determine a precoding matrix W indicating the horizontal direction of the first subcarrier_(CA1，2)PMI of_(CA1，2)Is the at least one first PMI; determining a precoding matrix W for indicating the horizontal direction of the second subcarrier_(CA2，2)PMI of_(CA2，2)Is the at least one second PMI. Based on the above condition, i.e. approximating a single path channel in the vertical direction, it can be ensured that the UE-transmitted PMI is received at the receiving unit_C、PMI_(CA1，2)、PMI_(CA2，2)According to the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). Enabling the base station to follow the PMI_CAnd PMI_(CA1，2)Determining the W_(CA1)(ii) a According to the PMI_CAnd PMI_(CA2，2)Determining the W_(CA2，2). The determination here may also be obtained by receiving an indication from the UE or other device or a negotiation determination of both.

According to the description of the above embodiments, when the precoding matrix of the first subcarrier can be decomposed into the vertical precoding matrix and the horizontal precoding matrix, the PMI may respectively indicate the vertical precoding matrix and the horizontal precoding matrix, and the receiving unit receives, by using the characteristic that the angle spread of the vertical beam is relatively small, the PMI that each subcarrier can be commonly used and the non-common PMI that cannot be commonly used, which are sent by the UE, where the total number of the fed-back PMIs K in the process of determining the two subcarrier precoding matrices by the determining unit at a time, is used to indicate Q precoding matrices under two subcarriers, and the number K of the fed-back PMIs smaller than the number of Q, so as to achieve the purpose of saving channel resources. It should be understood that, if the angular spread of the horizontal directional beam of the antenna is much smaller than the angular spread of the vertical directional beam due to a change in the position, channel characteristics, or other conditions of the antenna, the horizontal directional channel may be determined as a model approximating a single-path channel, the PMI for indicating the horizontal directional precoding matrix of the first subcarrier may be determined as the at least one common PMI, the PMI for indicating the vertical directional precoding matrix of the first subcarrier may be determined as the at least one first PMI, and the PMI for indicating the vertical directional precoding matrix of the second subcarrier may be determined as the at least one second PMI. The specific steps and flow are the same as those in the above embodiments, and are not described herein again.

It should be understood that the judgment on the channel model may be a condition determined by reaching a certain condition, and may be directly configured or calculated and determined according to the determination unit or the UE.

in another embodiment, an apparatus for feeding back another PMI is presented. The method may be, but is not limited to, an antenna scenario for 2d mimo. The precoding matrix of the first subcarrier is a first precoding matrix W of the first subcarrier₅And a second precoding matrix W₆The product of (a); the common PMI is the W₅PMI of (a) and the W₆One of the PMIs of (a); the first non-common PMI is the W₅PMI of (a) and the W₆Another one of the PMIs of (1); the precoding matrix of the second subcarrier is the first precoding matrix W of the first subcarrier₇And a second precoding matrix W₈The product of (a); the common PMI is the W₇PMI of (a) and the W₈One of the PMIs of (a); the first non-common PMI is the W₇PMI of (a) and the W₈Another one of PMIs ofAnd (4) respectively. For example, the precoding matrix of the first subcarrier is a long-term wideband characteristic matrix (the W) of the first subcarrier₅) And a short-term narrow-band characteristic matrix (the W)₆) The product of (a); the precoding matrix of the second subcarrier is a long-term wideband characteristic matrix (the W) of the second carrier₇) And a short-term narrow-band characteristic matrix (the W)₈) The product of (a);

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

B＝[b₀，b₁，...b₃₁]

X^(k)＝[b_{2k mod 32}b_{(2k+1)mod 32}b_{(2k+2)mod 32}b_{(2k+3)mod 32}]

Where mod is the modulo symbol.

Further obtaining said W₅＝W₅ ^(k)：

According to the W₅ ^(k)Constructing codebook set C₁：

W₅ ^(k)The matrix characterizes the long-term wideband properties of the channel, on the other hand, another PMI (for convenience, this PMI is referred to as PMI₆) For indicating to the base station from codebook set C₁At least one element (codebook) is selected and constructedThe W is₆. Constructing different codebook sets C for different RI₂. For example, when RI is 1, the codebook set may be configured as follows:

When RI is 2, the codebook set may be configured as follows:

Correspondingly, the formula:

W′_(CA1)＝W₅×W₆

can represent a selection matrix W₆From W₅The superposition of some columns is selected to form a precoding matrix corresponding to the first subcarrier. W is as described above₅ ^(k)A matrix comprising 4 beams, representing long-term wideband channel characteristics, can be shared by the first and second subcarriers and, therefore, can be for different beamsMay share one W₅And each subcarrier can independently feed back a matrix W embodying short-term narrow-band characteristics₆Corresponding PMI₆And a matrix W embodying short-term narrow-band characteristics₈Corresponding PMI₈. It should be understood that the specific values in the above example are only one example given for the sake of convenience, and may be varied by the antenna port, rank indication, or other parameters during the specific application. And the codebook and the selection manner are exemplary descriptions, and the invention claims codebooks and manners of selecting codebooks in other forms.

W 'mentioned above'_(CA1)＝W₅×W₆And W'_(CA2)＝W₇×W₈Formally, it may be applied in particular in 2D MIMO scenarios, where the precoding matrix may specifically be represented by a product of the long-term wideband characteristic and the short-term narrowband characteristic of the signal. Fig. 12 shows implementation steps of the base station apparatus when one precoding matrix can be shared due to its subcarrier long-term broadband characteristic.

A receiving unit 1201, configured to receive at least one common PMI, at least one first PMI, and at least one second PMI; wherein the at least one common PMI is used to indicate that a long-term wideband characteristic matrix is embodied; the at least one first PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in a first subcarrier; the at least one second PMI is used for indicating that a short-term narrowband characteristic matrix is embodied in the second subcarrier.

A determining unit 1201, configured to determine a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI, and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier.

For convenience of understanding, the present invention further provides a specific implementation manner for specifically determining the PMI by looking up a table, which can be used in a scenario where the precoding matrix is formed by multiplying the first subcarrier precoding matrix and the second subcarrier precoding matrix. It should be understood that the table lookup in the present invention may be a table that is stored in the UE or the base station and is looked up by the determining unit, where the table includes a corresponding relationship between the PMI and the matrix, and the table may be multiple in consideration of specific applications, so that the PMI and the specific precoding sub-matrix correspond to different tables under different RI values or other parameters. The determining unit may determine or acquire the required information in the table through the receiving unit; or an array or a relationship for querying the precoding matrix corresponding to the corresponding PMI value. It should be understood that the specific form of the table may be various, and may be a mapping relation or a functional relation stored in the UE or the base station memory, and the present invention is not limited thereto. For convenience of description, the present embodiment is described in a table form. The determining unit determines the long-term wideband matrix corresponding to the first subcarrier and the second subcarrier according to the PMI, and determines a corresponding table in the corresponding rank, for example, the value range of the rank indication is 1-4, then, it is determined that the corresponding table is needed in tables 1 to 4 (table 1 corresponds to rank indication 1, table 2 corresponds to rank indication 2, table 3 corresponds to rank indication 3, table 4 corresponds to rank indication 4):

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Determining one of tables 1-4 according to the RI, wherein after the receiving unit receives a common PMI (i1), a first PMI (i2) and a second PMI (i 2'), the determining unit determines the common PMI (i1) of the CA1 and the CA2 according to a specific usage scenario in the determined table₁) The short-term narrowband characteristic matrix of CA1 and the short-term narrowband characteristic matrix of CA2 are determined according to the first PMI and the second PMI.

It should be understood that, if there are multiple CAs, for example, CA1, CA2, and CA3, the receiving unit may also receive a common PMI, and for example, the PMI corresponding to the short-term narrowband characteristic matrices of CA1, CA2, and CA3 may be used as a common PMI, and feed back 1 time of the common PMI, so as to indicate the short-term narrowband characteristic matrices in three carriers, and the base station receives the common PMI fed back by the UE, so as to achieve the purpose of further saving resources. Of course, the present embodiment is also applicable to the long-term wideband characteristic and the vertical and horizontal precoding matrices, and will not be described herein again. Of course, there may be multiple PMIs common to multiple CAs.

Fig. 12 illustrates an embodiment, according to the table, the long-term wideband characteristic matrix of the first subcarrier precoding matrix may be shared with other subcarriers, PMIs corresponding to different subcarriers may be used as a common PMI, the determining unit receives the common PMI once when determining two precoding matrices of different subcarriers, the receiving unit receives a non-common PMI that cannot be commonly used by each subcarrier sent by the UE, and indicates 4 subcarrier precoding matrices under 2 subcarriers (that is, a long-term wideband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier and the second subcarrier, respectively), and the number k of the received PMIs smaller than the number of all 4 subcarrier precoding matrices that can be determined by the k PMIs, so as to achieve the purpose of saving channel resources. It should be understood that the determining unit may share the long-term wideband characteristic matrix of the first subcarrier precoding matrix with other subcarriers according to the table, and in other scenarios, a situation that the short-term narrowband characteristic matrix may be shared with other subcarriers may also occur, which corresponds to the determining manner in this embodiment and is not described herein again.

It should be understood that the embodiments of the present invention all determine precoding matrices under two subcarriers, and the present invention claims that when the number of subcarriers is more than two, there is a PMI that can be shared with other subcarriers in respective PMIs of the two subcarriers, and meanwhile, there may also be several subcarriers in a subcarrier that are different from PMIs fed back by any one of the at least two subcarriers, and PMIs corresponding to the several subcarriers adopt a form of separate feedback. For example, there are 3 subcarriers CA1, CA2, CA3, wherein although there are one or more common PMIs in CA1 and CA2, none of the PMIs of CA3 can be used as a common PMI with any PMIs of CA1 or CA2, and then the determining unit will determine a precoding matrix according to all PMIs fed back individually to CA 3.

Next, still another embodiment will be described with respect to a method of specifically determining a common PMI of the present invention. According to the embodiments shown in fig. 10-12, when a certain PMI of the first subcarrier is determined_aCertain PMI with a second subcarrier_bDifferent, but will PMI_aPMI used as second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the base station can directly determine that the common PMI is the PMI_a(ii) a Correspondingly, when PMI is to be transmitted_aPMI used for indicating second subcarrier_bWhen the channel characteristics of the system are within a certain tolerance range or meet a certain condition, the PMI can also be directly determined_aIs the common PMI; or when using a PMI_cWhen used as a common PMI for the first subcarrier and the second subcarrier, the PMI may be used_aAnd the PMI_bIn this case, when the channel characteristics of the system can satisfy a certain condition, the PMI may be directly determined_cAs the at least one common PMI. The above procedure may be determined at said determining unit of the UE or the base station. Optionally, the receiving unit may receive the at least one common PMI, the at least one first PMI, the at least one second PMI, and a compensation value δ, where the at least one common PMI and the at least one first PMI are used to determine a precoding matrix of a first subcarrier; what is needed isThe at least one common PMI, the at least one second PMI and the δ jointly indicate a precoding matrix of a second subcarrier, and the receiving unit receives the at least one common PMI, the at least one first PMI, the at least one second PMI and a compensation value δ transmitted by the UE. It should be understood that, the determining unit may also determine and receive the PMI of the second subcarrier as the at least one common PMI, receive a compensation value δ 'from the receiving unit, and determine the precoding matrix of the first subcarrier according to the at least one common PMI, the δ', and the at least one first PMI; determining a precoding matrix of the second subcarrier according to the at least one common PMI and the second PMI. In general, the number of bits or resources occupied by δ may be, but is not limited to, less than the number of bits or resources occupied by one PMI. In this case, the purpose of indicating the precoding matrix of two subcarriers more accurately can be achieved while saving resources.

Optionally, the receiving unit receives the first PMI compensation value δ₁And/or a second PMI compensation value delta₂Said delta₁A precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the₂A precoding matrix for co-determining the second subcarrier with the at least one common PMI and the at least one second PMI.

The determining unit determines that the receiving unit receives the first PMI compensation value δ₁And/or a second PMI compensation value delta₂There are three cases:

case 1:

the determining unit or UE determines the δ₁And delta₂Said receiving unit receiving said delta₁And delta₂；

Case 2:

the determining unit or UE determines the δ₁Said receiving unit receiving said delta₁；

Case 3:

the determining unit or UE determines the δ₂Said receiving unit receiving said delta₂。

It should be understood that the receiving unit receives the delta₁And delta₂The order of the PMIs to be received by the receiving unit is not limited, and the PMIs may be received simultaneously or sequentially. When the determination unit determines the δ₁And/or delta₂Then, the delta can be transmitted by a transmitting unit₁And/or delta₂Sending to the UE or receiving the delta by a receiving unit₁And/or delta₂. According to different scenes corresponding to the public PMI, the invention provides three specific implementation modes:

embodiment 13:

since the angle spread in the vertical direction is much smaller than the angle spread in the horizontal direction, the vertical direction approximates to a single-path channel, and the determining unit may determine the vertical direction channel as an approximate single-path channel model, as an example, in embodiment 4, determine W_(CA1，1)Corresponding PMI_(CA1，1)The determination unit determines the PMI as one common PMI_(CA1，1)And said W_(CA2，1)Corresponding PMI_(CA2，1)May be represented by delta_aAnd (4) determining. Determining W_(CA1，2)Corresponding PMI_(CA1，2)Determining W for the first PMI_(CA2，2)Corresponding PMI_(CA2，2)The second PMI, here, the common PMI and the first PMI are used to determine: (respectively)Indication) W_(CA1，1)And said W_(CA1，2)The common PMI, the delta_aDetermining the W_(CA2，1)Said second PMI said W_(CA2，2)So that the determining unit confirms the first subcarrier precoding matrix W_(CA1)、W_(CA2). It should be understood that PMI is determined_(CA2，1)As the common PMI, δ is correspondingly used_a' and the common PMI indicate the W_(CA1)The method can be the same as the above method, and is not described again.

Embodiment 14:

W′_(CA1)＝W₅×W₆

W′_(CA2)＝W₇×W₈

the matrix W5 representing the long-term wideband channel characteristics of CA1 may be implemented as PMI₅Indication, the matrix W7 representing the long-term wideband channel characteristics of CA2 may be PMI₅And a compensation value delta_bIndicating that, as an example, a PMI (PMI) corresponding to W5 is determined₅) As the common PMI, a PMI (PMI) corresponding to W6₆) A PMI (PMI) corresponding to W8 as the first PMI₈) For the second PMI, in one embodiment, the common PMI is used for determining (indicating) the W5, the first PMI is used for determining (indicating) the W6, and the second PMI is used for indicating the W8, the common PMI, and the δ_bFor indicating the W7, the W5, W6 for determining the W'_(CA1)The W7, the W8 are used to determine the W'_(CA2)(ii) a In another embodiment, the determining unit determines the corresponding table in tables 1-4, i in the common PMI corresponding table, according to rank indication₁I in the first PMI correspondence table₂The determining unit determines a precoding matrix W corresponding to the first subcarrier; the common PMI and the delta_b' carry out operationThe obtained value corresponds to i in the table₁I in the second PMI correspondence table₂The determining unit determines a precoding matrix W corresponding to the second subcarrier₂. It should be understood that the method for determining the PMI7 as the common PMI is the same as the above embodiments, and is not described again.

Embodiment 15:

according to the above embodiments, two compensation values, δ, may also be given simultaneously by the determining unit or the UE_cAnd delta_d. In this case, the δ_cA precoding matrix for determining the first subcarrier in cooperation with the at least one common PMI and the at least one first PMI; delta. the_dA precoding matrix for determining the second subcarrier in cooperation with the at least one common PMI and the at least one second PMI.

It should be understood that, the above-mentioned various embodiments for determining the compensation value give a basis or an order of determination, the specific determination method is not limited by the present invention, and the determination manner of the compensation value may be different according to the allocated bit number, for example, when the common PMI is used to indicate that the error of the first subcarrier precoding matrix and the second subcarrier precoding matrix is not large (i.e. can be within a tolerance range), 1 bit may be allocated, 0 represents no compensation, 1 represents compensation, and the specific compensation value may be predefined; in one embodiment, PMI_XAnd PMI_YFor indicating a first subcarrier precoding matrix, PMI_ZAnd PMI_WFor indicating the second subcarrier precoding matrix. When the determination unit determines that the common PMI may be a simultaneous indication PMI_XAnd PMI_ZI.e. common PMI and PMI_Y(PMI here)_YEquivalent to the first PMI) indicates a precoding matrix of a first subcarrier; common PMI and PMI_Z(PMI here)_WEquivalent to the second PMI) indicates a precoding matrix of a second subcarrier; when the determination unit determines PMI_XWhen the PMI is equal to 7, the PMI may be identical to the first PMI (may be a PMI in this embodiment)_Y) Jointly indicate the first subcarrier precoding matrix if PMI_WCorresponding characteristics and PMI_XIs not very different or the same, i.e., PMI can be determined_WWhen δ is received by the base station, it can be determined that compensation is not needed as long as δ is 0; however, if the system determines to use PMI_W10 and the second PMI (which may be a PMI in this embodiment)_W) When the second subcarrier precoding matrix is indicated jointly to be accurate, then using the common PMI of 7 and the second PMI to indicate the second subcarrier precoding matrix jointly may bring about a relatively large error, where the system may be the base station, the UE, or another network device notifying the base station. However, if the offset value δ preset by the system is 1 to represent offset 3, then 1 bit may accurately indicate that the base station or UE side needs to compensate 3 again with common PMI of 7, and then determine the second subcarrier precoding matrix together with the second PMI. It should be understood that, for this example, in some scenarios, if the compensation value δ of the system preset is 1 to represent the compensation 2, the value indicated jointly by the common PMI and the compensation value is 9, which is also acceptable if within some tolerable range.

It should be understood that the method of determining or receiving the compensation value by the determining unit is merely an example, and the determination or reception of the compensation value may be combined with any of the embodiments of transmitting the compensation value, and other embodiments of the present invention, within the scope of logic.

The base station apparatus may receive a vertical precoding matrix or a long-term broadband characteristic precoding matrix of a certain subcarrier as the common PMI and then receive a compensation value δ under different channel models by using a single path characteristic in a vertical direction of different subcarriers or a long-term broadband characteristic similarity of different subcarriers; the determining unit determines a vertical direction precoding matrix or a long-term wideband characteristic precoding matrix of another subcarrier from the δ and the common PMI. And determining the precoding matrixes under different subcarriers according to the first PMI and the second PMI, thereby saving channel resources and improving the indication precision.

Fig. 13 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. To a user equipment, UE, for feedback of precoding matrix indicator, PMI, for a wireless communication system with multi-carrier capability, the UE communicating with a base station using a first subcarrier and a second subcarrier. The method specifically comprises the following steps:

a processor 1301, configured to determine at least one common PMI, at least one first PMI, and at least one second PMI, where the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; wherein the common PMI, the first PMI and the second PMI may be 2, 3 or more than 3, respectively. The specific functions in step 101 may be implemented, and the determining unit in fig. 7, 8, and 9 may also be implemented in the form of the processor.

A transmitter 1302, configured to transmit the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system. The specific function in step 102 may be implemented, and the transmitting unit in fig. 7, 8, and 9 may also be implemented in the form of the transmitter.

In an embodiment, in order to determine the specific manner of determining the at least one common PMI, the at least one first PMI and the at least one second PMI, when both sides may determine the common PMI, the at least one first PMI and the at least one second PMI according to a rule, the UE further includes a receiver 1303 configured to receive a first message sent by the base station, and the processor determines the at least one common PMI, the at least one first PMI and the at least one second PMI according to the first message. In another embodiment, after the processor determines the at least one common PMI, the at least one first PMI and the at least one second PMI, the transmitter 1302 is further configured to transmit a second message. Furthermore, the receiving unit in fig. 7, 8, 9 may also be implemented in the form of this receiver.

In one embodiment, the UE includes a memory 1304 for storing messages or signaling, codebooks, or decision rules

Fig. 14 is a schematic configuration diagram of a communication apparatus according to an embodiment of the present invention. To a base station for feedback of precoding matrix indicator, PMI, for use in a multi-carrier capable wireless communication system, the base station communicating with a UE using a first subcarrier and a second subcarrier. The method specifically comprises the following steps:

a receiver 1401 for receiving at least one common PMI, at least one first PMI, and at least one second PMI; the receiving unit in fig. 10, 11, 12 may also be implemented in the form of the processor.

A processor 1402 configured to determine a precoding matrix of a first subcarrier and a precoding matrix of a second subcarrier according to the at least one common PMI, the at least one first PMI, and the at least one second PMI; wherein the at least one common PMI and the at least one first PMI are used to indicate a precoding matrix of the first subcarrier; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier. The determining unit in fig. 10, 11, 12 may be a processing unit or may be implemented in the form of a processor.

In one embodiment, when the processor 1401 is used for determining the specific manner when determining the at least one common PMI, the at least one first PMI and the at least one second PMI, so that both sides may determine the common PMI, the at least one first PMI and the at least one second PMI according to a rule, it needs to send an indication to or negotiate with a UE for determination, and the base station further includes a transmitter 1403, configured to send a first message to the UE after the processor determines the at least one common PMI, the at least one first PMI and the at least one second PMI according to the first message, so as to indicate the UE to determine the at least one common PMI, the at least one first PMI and the at least one second PMI according to the first message. In another embodiment, the receiver receives a second message sent by another network-side device, and the processor determines the at least one common PMI, the at least one first PMI, and the at least one second PMI according to the second message. The transmitter 1403 is also used for transmitting a second message. The receiving unit in fig. 10, 11, and 12 may be implemented as the receiver.

In one embodiment, the base station includes a memory 1404 for storing messages or signaling, codebooks, or decision rules

The transmitter 1302 shown in fig. 13 may be an antenna or a wireless transmitter, and the receiver 1303 may be an antenna or a wireless receiver, and the transmitter and the receiver may be the same antenna or a wireless transceiver.

The transmitter 1403 referred to in fig. 14 may be an antenna, or a wireless transmitter, and the receiver 1401 may be an antenna, or a wireless receiver, and the transmitter and the receiver may be the same antenna or a wireless transceiver.

The Processor shown in fig. 13 and/or fig. 14 may be a general-purpose Processor, such as a general-purpose Central Processing Unit (CPU), a Network Processor (NP), a microprocessor, etc., or may be an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program according to the present invention. But may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. Or multiple processors may perform different functions.

The memory according to fig. 13 and/or 14 stores a program for executing the present invention, and may store an operating system and other application programs. In particular, the program may include program code including computer operating instructions. More specifically, the memory may be a read-only memory (ROM), other types of static storage devices that may store static information and instructions, a Random Access Memory (RAM), other types of dynamic storage devices that may store information and instructions, a disk storage device, and so forth. Or may be a different memory storage.

From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by hardware, firmware, or a combination thereof. When implemented in software, the functions described above may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. Taking this as an example but not limiting: computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Furthermore, the method is simple. Any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a Digital Subscriber Line (DSL), or a wireless technology such as infrared, radio, and microwave, the coaxial cable, the fiber optic cable, the twisted pair, the DSL, or the wireless technology such as infrared, radio, and microwave are included in the fixation of the medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy Disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

In short, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A feedback method of Precoding Matrix Indicator (PMI) is used for a wireless communication system with multi-carrier capability, and User Equipment (UE) in the wireless communication system communicates with a network side device by using a first subcarrier and a second subcarrier, and the method comprises the following steps:

the UE determines a first PMI compensation value delta, at least one common PMI, at least one first PMI and at least one second PMI, wherein the delta is used for indicating a precoding matrix of the first subcarrier together with the at least one common PMI and the at least one first PMI; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the common PMI is determined based on PMIs corresponding to the first subcarrier and the second subcarrier, and the total number of PMIs of the common PMI, the first PMI and the second PMI is less than the number of precoding matrixes corresponding to the first subcarrier and the second subcarrier;

the UE transmits the delta, the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system.

2. The method of claim 1,

the precoding matrix of the first subcarrier is a kronecker product of a vertical precoding matrix of the first subcarrier and a horizontal precoding matrix of the first subcarrier; the precoding matrix of the second subcarrier is a kronecker product of a vertical precoding matrix of the second subcarrier and a horizontal precoding matrix of the second subcarrier;

the common PMI is used for indicating a vertical precoding matrix of the first subcarrier; the common PMI is also used for indicating a vertical precoding matrix of a second subcarrier;

the first PMI is used for indicating a horizontal direction precoding matrix of the first subcarrier;

the second PMI is used for indicating a horizontal precoding matrix of the second subcarrier.

3. The method of claim 2,

4. The method of claim 1,

the precoding matrix of the first subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the first subcarrier; the precoding matrix of the second subcarrier is the product of a long-term broadband characteristic matrix and a short-term narrowband characteristic matrix of the second subcarrier;

5. The method of claim 1, further comprising:

the UE determines a first PMI compensation value δ, including:

and determining the first PMI compensation value delta according to the second subcarrier precoding matrix and the first subcarrier precoding matrix.

6. The method according to claim 1 or 5, wherein the UE sending the first PMI compensation value δ specifically includes:

and transmitting the first PMI compensation value delta through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).

7. A feedback method of Precoding Matrix Indicator (PMI) is used for a wireless communication system with multi-carrier capability, wherein a base station in the wireless communication system communicates with a User Equipment (UE) by using a first subcarrier and a second subcarrier, and the method comprises the following steps:

the base station receives a first PMI compensation value delta, at least one common PMI, at least one first PMI and at least one second PMI, wherein the delta is used for indicating a precoding matrix of the first subcarrier together with the at least one common PMI and the at least one first PMI; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the common PMI is determined based on PMIs corresponding to the first subcarrier and the second subcarrier, and the total number of PMIs of the common PMI, the first PMI and the second PMI is less than the number of precoding matrixes corresponding to the first subcarrier and the second subcarrier;

the base station determines a precoding matrix of the first subcarrier according to the delta, the at least one common PMI and the at least one first PMI, and determines a precoding matrix of a second subcarrier according to the at least one common PMI and the second PMI.

8. The method of claim 7,

9. The method of claim 8, comprising:

10. The method of claim 7,

11. The method as claimed in claim 7, wherein the receiving, by the base station, the first PMI compensation value δ specifically includes:

and the base station receives the first PMI compensation value delta through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).

12. A Precoding Matrix Indicator (PMI) feedback apparatus, configured to be used in a wireless communication system with multi-carrier capability, wherein a User Equipment (UE) in the wireless communication system communicates with a network side device using a first subcarrier and a second subcarrier, and the UE comprises:

a determining unit, configured to determine a first PMI compensation value δ, at least one common PMI, at least one first PMI, and at least one second PMI, where δ is used to indicate a precoding matrix of the first subcarrier in common with the at least one common PMI and the at least one first PMI; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the common PMI is determined based on PMIs corresponding to the first subcarrier and the second subcarrier, and the total number of PMIs of the common PMI, the first PMI and the second PMI is less than the number of precoding matrixes corresponding to the first subcarrier and the second subcarrier;

a transmitting unit configured to transmit the δ, the at least one common PMI, the at least one first PMI, and the at least one second PMI to a base station in the wireless communication system.

13. The UE of claim 12, comprising:

14. The UE of claim 13, comprising:

15. The UE of claim 12, comprising:

16. The UE of claim 12, wherein the determining unit is further configured to determine the first subcarrier precoding matrix and the second subcarrier precoding matrix; the determining unit determines the at least one common PMI according to the first subcarrier precoding matrix;

the determining unit determines a first PMI compensation value δ, including:

17. The UE according to claim 12 or 16, wherein the sending unit sends the first PMI compensation value δ specifically includes:

18. A feedback apparatus of Precoding Matrix Indicator (PMI), for a wireless communication system with multi-carrier capability, wherein a base station in the wireless communication system communicates with a User Equipment (UE) by using a first subcarrier and a second subcarrier, the base station comprising:

a receiving unit, configured to receive a first PMI compensation value δ, at least one common PMI, at least one first PMI, and at least one second PMI, where δ is used to indicate a precoding matrix of the first subcarrier in common with the at least one common PMI and the at least one first PMI; the at least one common PMI and the at least one second PMI are used to indicate a precoding matrix of the second subcarrier; the common PMI is determined based on PMIs corresponding to the first subcarrier and the second subcarrier, and the total number of PMIs of the common PMI, the first PMI and the second PMI is less than the number of precoding matrixes corresponding to the first subcarrier and the second subcarrier;

a determining unit, configured to determine a precoding matrix of the first subcarrier according to the δ, the at least one common PMI and the at least one first PMI, and determine a precoding matrix of a second subcarrier according to the at least one common PMI and the second PMI.

19. The base station of claim 18, comprising:

20. The base station of claim 19, comprising:

21. The base station of claim 18, comprising:

22. The base station of claim 18, wherein the receiving unit receives the first PMI compensation value δ specifically includes:

the receiving unit receives the first PMI compensation value δ through a physical uplink control channel PUCCH or a physical uplink shared channel PUSCH.