WO2014153681A1

WO2014153681A1 - Multi-antenna channel codebook feedback method and apparatus in mimo system

Info

Publication number: WO2014153681A1
Application number: PCT/CN2013/000353
Authority: WO
Inventors: 武露; 刘皓
Original assignee: 阿尔卡特朗讯; 上海贝尔股份有限公司
Priority date: 2013-03-27
Filing date: 2013-03-27
Publication date: 2014-10-02
Also published as: CN105075142B; CN105075142A

Abstract

The present invention relates to a multi-antenna channel codebook feedback method and apparatus in a multiple input multiple output (MIMO) system. In an embodiment, a multi-antenna channel feedback method applied in a MIMO system is provided, comprising: detecting a downlink multi-antenna channel; determining a rank according to a result of detecting the downlink multi-antenna channel, and selecting, based on a pre-determined rule, a codeword from a pre-determined codebook corresponding to the rank; and feeding back an index of the selected codeword and the rank, any codeword in the pre-determined codebook being a product of a first matrix indicating long-term broadband channel information and a second matrix indicating short-term narrowband channel information. In the technical solutions of the present invention, for MIMO multi-antenna channel feedback, finer beam selection and multiple vectors in a discrete Fourier form are implemented, and various antenna configurations comprising a closely-arranged cross-polarized linear array, a sparsely-arranged cross-polarized linear array, and a uniform linear array are supported.

Description

Multi-antenna channel codebook feedback method and device in MIMO system

The present invention relates generally to mobile communication technologies and, more particularly, to a Multiple User Multiple Input Multiple Output (MU MIMO) transmission technique. Background technique

In the system of Release 10 (RIO) of the Long Term Evolution (LTE), when the base station, ie, evolved Node B (eNB), is configured with a 4-antenna cross-polarized antenna array Because the codebook of Release 10 is not accurate enough for such antenna settings, the effect of downlink multi-user multiple input and multiple output is not as good as expected. Summary of the invention

It is a primary object of the present invention to provide a new technical solution for codebook feedback for a MU-MIMO system and to overcome the above-discussed deficiencies in the prior art.

In one embodiment, a method for multi-antenna channel feedback for a multiple input multiple output system is provided, including: detecting a downlink multi-antenna channel; determining a rank based on a detection result of the downlink multi-antenna channel, based on a predetermined criterion selects a codeword from a predetermined codebook corresponding to the rank; and feeds back an index of the selected codeword and the rank; wherein any one of the predetermined codebooks is long a product of a first matrix of time-band wideband channel information and a second matrix representing short-term narrowband channel information, the first matrix being a diagonal matrix having a number of rows and columns equal to the number of transmitting antennas, and the number of rows of the second matrix being equal to a transmitting antenna The number, the number of columns is equal to the rank; wherein, the sample set of the first matrix includes a first set and a second set, and any sample in the first set includes two identical discrete Fourier transform forms a semi-long diagonal matrix, any one of the second sets being a full-length diagonal matrix in the form of a discrete Fourier transform; wherein each column of the second matrix a first half-length vector corresponding to a first polarization direction and a second half-length vector corresponding to a second polarization direction, the first half-length vector representing a beam offset with respect to the first matrix, the The two-half long vector represents the beam offset with respect to the first matrix, the inter-polarization beam offset of the second polarization direction with respect to the first polarization direction, and the phase offset.

In another embodiment, an apparatus in a user equipment for a multiple input multiple output system is provided, comprising: a detecting module, configured to detect a downlink multi-antenna channel; a determining module, configured to determine a rank according to a detection result of the downlink multi-antenna channel, and select a codeword from a predetermined codebook corresponding to the rank based on a predetermined criterion; a feedback module, configured to feed back an index of the selected codeword and the rank; wherein, any one of the predetermined codebooks is a first matrix indicating long-term broadband channel information and a first-time narrowband channel information a product of a second matrix, wherein the first matrix is a diagonal matrix having a number of rows and columns equal to the number of transmitting antennas, and the number of rows of the second matrix is equal to the number of transmitting antennas, and the number of columns is equal to the rank; wherein, the first matrix The sample set includes a first set and a second set, and any sample in the first set includes two semi-long diagonal matrices in the same discrete Fourier transform form, and any sample in the second set is a full-length diagonal matrix of a discrete Fourier transform form; wherein each column of the second matrix includes a first half-length vector corresponding to a first polarization direction and corresponds to a a second half-length vector of a polarization direction, the first half-length vector representing a beam offset relative to the first matrix, the second half-length vector representing a beam offset, a second polarization relative to the first matrix The inter-polarization beam offset and phase offset of the direction relative to the first polarization direction.

In one embodiment, the first set or the second set of the first matrix is an empty set.

In one embodiment, the downstream multi-antenna uses a cross-polarized linear array.

In one embodiment, the downlink multi-antenna uses a uniform linear array.

In one embodiment, when the rank is 2, the second column of the second matrix is further distinguished from the first column by a differential beam offset factor and a differential phase shift factor.

In yet another embodiment, a user equipment for a multiple input multiple output system is provided that includes the aforementioned apparatus.

The above technical features and advantages of the present invention are summarized to make the following detailed description of the present invention easier to understand. Other features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. Those skilled in the art will appreciate that the disclosed concepts and embodiments can be readily utilized as a basis for modifying or designing other structures or processes for achieving the same objectives as the present invention. Those skilled in the art should understand that such equivalent constructions do not depart from the spirit and scope of the appended claims. DRAWINGS

The detailed description of the preferred embodiments of the present invention will be understood as The invention is illustrated by way of example and not limitation of the drawings.

Figure 1 illustrates an application scenario in accordance with one embodiment of the present invention;

2 shows a flow chart of a PMI feedback method suitable for a MIMO system according to an embodiment of the present invention. FIG. 3 shows a schematic structural diagram of an apparatus suitable for a MIMO system user equipment according to an embodiment of the present invention. detailed description

The detailed description of the drawings is intended to be illustrative of the preferred embodiments of the invention It is to be understood that the same or equivalent functions may be carried out by various embodiments which are intended to be included within the spirit and scope of the invention.

Those skilled in the art will appreciate that the means and functions described herein can be used in conjunction with programming! The software functions of the processor and the general purpose computer are implemented, and/or implemented using an application specific integrated circuit (ASIC). It should also be understood that although the invention has been described primarily in terms of methods and apparatus, the invention may also be embodied in a computer program product and a system comprising a computer processor and a memory coupled to the processor, wherein the memory can be used to accomplish this One or more programs of the disclosed functionality are encoded.

FIG. 1 shows a schematic diagram of an application scenario according to an embodiment of the present invention. The technical solution of the present invention is suitable for a multiple input multiple output system. As shown in the figure, the base station device 1 and the user equipment 2 are included in the scenario. The technical solution of the present invention is suitable for, for example, but not limited to, Precoding Matrix Index (PMI) feedback between the base station device 1 and the user equipment 2. It should be understood by those skilled in the art that the base station or the base station device referred to herein is, for example but not limited to, the Node B or the evolved Node B (eNB) in the LTE system or the LTE-A system, and the present invention The technical solution is also not limited to the applicable LTE system or the LTE-A system.

2 shows a flow chart of a PMI feedback method suitable for a MIMO system in accordance with one embodiment of the present invention. As shown, the method 20 includes steps 22, 24, and 26 performed by the user device 2. In step 22, the user equipment 2 detects the downlink multi-antenna channel. For example, but not limited to, the multiple antennas of the downlink multi-antenna channel detected by the user equipment 2 are the transmitting antennas of the base station apparatus 1. The number of antennas of the downlink antenna array is usually an even number of 4 or more, such as but not limited to 4, 6, 8, and the like. In step 24, the user equipment 2 determines a rank based on the detection result of the downlink multi-antenna channel, and selects one codeword from a predetermined codebook corresponding to the rank based on a predetermined criterion. In step 26, user equipment 2 feeds back the index of the selected codeword and the rank.

The composition of any one of the predetermined codebooks W can be expressed by the following formula

W = Wi * W ₂ ( 1 ). The first matrix is a diagonal matrix, representing long-term wideband channel information, the number of rows and columns is equal to the number of transmitting antennas; the second matrix w ₂ represents short-term narrowband channel information, the number of rows being equal to the number of transmitting antennas, and the number of columns is equal to rank.

The sample set of the first matrix includes a first set and a second set, and any sample in the first set includes two semi-long diagonal matrices in the same discrete Fourier transform form, the second set Any of the samples is a full-length diagonal matrix in the form of a discrete Fourier transform.

In one embodiment, any of the samples in the sample set of the first matrix can be formulated as follows

Where “e {0,. , Nl} , N represents the number of samples, and Ν _τ represents the number of transmitting antennas. The first matrix ^" in this embodiment belongs to the first set, and the corresponding second set is an empty set.

In another embodiment, any of the samples in the sample set of the first matrix can be formulated as follows

1

w ( 3 )

Where "e {0,. , Nl} , N represents the number of samples, and _{τ τ} represents the number of transmitting antennas. The first matrix ^" in this embodiment belongs to the second set, and the corresponding first set is an empty set.

In yet another embodiment, the first set and the second set are both non-empty sets. Any sample in the first set can be expressed as a formula

Any sample in the second set can be publicized as

W, ^3⁄4 =1 ( 5 ).

Where w^S, n ₂ GS ₂ , ^U^ ₂ ={0,---,Nl} , SUS ₂ = . For example, but not limited to, as. To N-1 The odd number in , is an even number from 0 to N- l.

The codeword number of the codebook is usually an integer power of two. N is, for example but not limited to, 8, 16, and the like. When N is 8, the first matrix Wi can be fed back by using a 3-bit index; when N is 16, the first matrix Wi can be fed back by using a 4-bit index.

Each column of the second matrix W ₂ includes a first half-length vector corresponding to a first polarization direction and a second half-length vector corresponding to a second polarization direction, the first half-length vector representing relative to the first matrix Beam offset, the second half-length vector representing a beam offset with respect to the first matrix, an inter-polarization beam offset of the second polarization direction with respect to the first polarization direction, and a phase offset.

In one embodiment, the rank determined by the user equipment 2 is 1, and the second matrix can be expressed by the following

As shown in the formula (6), the second matrix W ₂ includes two half-length vectors respectively corresponding to one polarization direction of the transmitting antenna. Wherein, the superscript T represents matrix transposition, e represents a finer beam offset factor in one polarization direction with respect to long-term feedback, and e ^w represents inter-polarization beam offset between two polarization directions A factor indicating the phase shift (phase shift) factor of the second polarization direction with respect to the first polarization direction.

In another embodiment, the rank determined by the user equipment 2 is 2, and the second column of the second matrix W ₂ is further distinguished from the first column by a differential beam offset factor and a differential phase shift factor. The second matrix can be expressed as follows

(1, …,

₍₁ , _e K^)-^ ..., + ). ( - "), _e Ha _φ+ β ..., ( - ),

(7). As shown in the formula (7), the second matrix W ₂ includes two columns, respectively corresponding to two ranks (or two data streams), and the composition of the first column is the same as the formula (6). A differential beam offset factor between two ranks (or two data streams), "representing the differential phase shift factor between two ranks (or two data streams).

For closely aligned cross-polarized linear antenna arrays (eg, antenna spacing is approximately half the carrier wavelength), β, , can be set to a fixed value, such as ^ = 0, Αφ = 0. α = π. In order to simultaneously support closely arranged cross-polarized linear antenna arrays and sparsely arranged cross-polarized linear antenna arrays (e.g., antenna spacing is about 4 times carrier wavelength), β, Α φ can be set to multiple values, respectively.

It should be understood by those skilled in the art that the downlink transmission may be performed by one base station or may be performed by multiple base stations. The multiple transmit antennas of the downlink multi-antenna channel detected by the user equipment 2 may be configured in the same base station, or may be configured. It is distributed over multiple base stations.

In one (first) embodiment, the number of downlink transmit antennas is 4, and the number of samples of the first matrix \¥ ₁ is 16. Use 4-bit index feedback. a set of representations

Second set representation

Me {0,1,...,7}

For a rank of 1 or 2, the same first matrix W is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e ^j<p , the polarization offset factor e ^jl) , and the phase shift factor respectively use 1 bit, 1 bit, 2 bits of freedom, where φ & {0, 2 /16}, fi {Ο, π} , oe {0, /2, , 3 /2} , = 0 , = τ. Second matrix W ₂釆 4-bit index feedback.

When the rank is 1, the second matrix W _{2 is} expressed as

W ₂ =[(l, 0, e ^ja (l, ] ^Γ .

When the rank is 2, the second matrix W _{2 is} expressed as

(1, e ⁱ ), e ^ja (\, ε ^Κφ+β) )

W, =

(1, e ⁱ ), -e ^ja (\, ε ^Κφ+β) )

The predetermined codebook in this embodiment has two finer beam selections, with 16 discrete Fourier forms of vectors, and the entire codebook supports a closely arranged cross-polarized linear array, sparsely arranged cross-polarized linearity. Various antenna configurations including arrays and uniform linear arrays.

In another (second) embodiment, the number of downlink transmit antennas is four. The number of samples of the first matrix \¥ is 8, 3 using 3-bit index feedback, and is expressed as the form shown in equation (2)

For a rank of 1 or 2, the same first matrix, the second matrix W _{2 is} used in the form represented by equation (6) or (7), and its beam offset factor e, polarization offset factor phase shift factor Use 2 bits, 1 bit, 1 bit of freedom, respectively, where {0,2 /16,4 /16,6 /16} , fi {Ο,π} , ae {Ο,π} , Αφ = 0 , α = π. The second matrix W ₂ uses 4-bit index feedback. The predetermined codebook in this embodiment has four more fine Beam selection, with four discrete Fourier forms of the vector, the entire codebook supports a variety of antenna configurations including tightly arranged cross-polarized linear arrays, sparsely arranged cross-polarized linear arrays, and uniform linear arrays.

In another (third) embodiment, the number of downlink transmit antennas is four. The number of samples of the first matrix \¥ is 16, using 4-bit index feedback, and using the form shown in equation (2). For a rank of 1 or 2, the same first matrix W is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e, the polarization offset factor _e ^? , the phase shift factor ", and the differential beam offset factor ^ respectively Use 1 bit of freedom, where φ υ φβ], fi {Ο, π} , oe {0, π/2}, Α φ & {Ο, π}, α = π. The second matrix W ₂ 4 uses 4-bit index feedback .

In another (fourth) embodiment, the number of downlink transmit antennas is four. The number of samples of the first matrix \¥ is 8, using 3-bit index feedback, and using the form shown in equation (2). For a rank of 1 or 2, the same first matrix W is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e, the polarization offset factor e ^? , and the phase shift factor are respectively 1 bit, 1 bit, 2 Degree of freedom of bits, where φ

π. The second matrix W ₂ uses 4-bit index feedback.

In another (fifth) embodiment, the number of downlink transmit antennas is four. The sample number of the first matrix \¥ ₁ is 16, and the 4-bit index feedback is used, and the form shown in the formula (2) is used. For a rank of 1 or 2, the same first matrix Wi is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e and the phase shift factor respectively use 2 bits of freedom, wherein φ

, β = 0, oe {0, /2, , 3 /2}, Αφ = 0, α=π. The second matrix W ₂ uses 4-bit index feedback.

In another (sixth) embodiment, the number of downlink transmit antennas is four. The number of samples of the first matrix \¥ is 16, using 4-bit index feedback, and using the form shown in equation (2). For a rank of 1 or 2, the same first matrix W is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e and the phase shift factor respectively use a 1-bit, 3-bit degree of freedom, where {0, 2 /16} , β = 0 , oe {0, /4, /2,3 /4, ,5 /4,6 /4,7 /4} , Αφ = 0, α = π. Second matrix W ₂釆Use 4-bit index feedback.

In another (sixth) embodiment, the number of downlink transmit antennas is four. The number of samples of the first matrix \¥ is 16, using 4-bit index feedback, and using the form shown in equation (2). For a rank of 1 or 2, the same first matrix W is used. The second matrix W ₂ is in the form represented by the formula (6) or (7), and the beam offset factor e and the phase shift factor respectively use a 1-bit, 3-bit degree of freedom, where φ {0, 1φ1, β = 0, oe {0, /4, /2,3 /4, , 5 /4,6 /4,7 /4} , Αφ = 0, α = π. The second matrix W ₂ applies 4 bit cable Give feedback.

In some other embodiments, for a rank of 1 or 2, a different first matrix Wi is used. For example, but not limited to, for a rank of 1, the first matrix \¥ 釆 is in the form shown in equation (2); for a rank of 2, the first matrix \¥ _{1 is} used as equations (4) and (5) The form of the show.

The values or ranges of values given in the above embodiments are illustrative and not limiting, and any other suitable value or range of values is preferred. The predetermined codebooks in the above embodiments mostly have a plurality of finer beam selections and multiple discrete Fourier forms of vectors, and the entire codebook supports a closely arranged cross-polarized linear array, sparsely arranged cross-polarization. Various antenna configurations, including linear arrays and linear arrays.

FIG. 3 shows a block diagram of a device 30 suitable for a MIMO system user equipment in accordance with one embodiment of the present invention. The device 30 is typically disposed in the user device 2, and as shown, the device 30 includes a detection module 31, a determination module 33, and a feedback module 35. The detection module 31 is configured to detect the downlink multi-antenna channel, corresponding to performing step 22 of the foregoing method 20. The determining module 33 is configured to determine a rank according to the detection result of the downlink multi-antenna channel, and select one codeword from a predetermined codebook corresponding to the rank based on a predetermined criterion, corresponding to performing step 24 in the foregoing method 20. The feedback module 35 is configured to feed back the index of the selected codeword and the rank, corresponding to performing step 26 of the foregoing method 20. The predetermined codebook may be in the form described in any of the foregoing method embodiments.

Those skilled in the art should understand that the functions of any of the above modules may be performed by multiple physical modules or functional modules, and the functions of the above multiple modules may also be integrated into one physical module or functional modules for execution. Although various embodiments of the invention have been illustrated and described, the invention is not limited to the embodiments. The ordinal numbers such as "first" and "second" appearing in the claims only serve to distinguish them, and do not imply any specific order or connection between the components. The mere appearance of technical features in certain claims or embodiments is not intended to be combined with other features in other claims or embodiments to implement a beneficial new technical solution. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the scope of the invention.

Claims

Claim

A method for multi-antenna channel feedback for a multiple input multiple output system, comprising:

Detecting a downlink multi-antenna channel;

Determining a rank according to a detection result of the downlink multi-antenna channel, selecting one codeword from a predetermined codebook corresponding to the rank based on a predetermined criterion;

Feedbacking the index of the selected codeword and the rank;

Any codeword in the predetermined codebook is a product of a first matrix representing long-term wideband channel information and a second matrix representing short-term narrowband channel information, where the number of rows and columns is equal to the number of transmitting antennas. a diagonal matrix, the number of rows of the second matrix is equal to the number of transmitting antennas, and the number of columns is equal to the rank;

The sample set of the first matrix includes a first set and a second set, and any sample in the first set includes two semi-long diagonal matrices in the same discrete Fourier transform form, the Any one of the two sets is a full-length diagonal matrix in the form of a discrete Fourier transform;

Each column of the second matrix includes a first half-length vector corresponding to a first polarization direction and a second half-length vector corresponding to a second polarization direction, the first half-length vector representing a relative A beam offset of a matrix, the second half-length vector representing an inter-polarization beam offset and a phase offset with respect to the first matrix beam offset, the second polarization direction relative to the first polarization direction.

2. The method of claim 1, wherein the first set or the second set is an empty set.

3. The method according to claim 1, wherein the downlink multi-antenna uses a cross-polarization linear array.

4. The method according to claim 1, wherein the downlink multi-antenna uses a uniform linear array.

The method according to claim 1, wherein when the rank is 2, the second column of the second matrix is further distinguished by the differential beam offset factor and the differential phase shift factor in the first column. .

6. A device in a user equipment for a multiple input multiple output system, comprising:

a detecting module configured to detect a downlink multi-antenna channel;

a determining module, configured to determine a rank according to a detection result of the downlink multi-antenna channel, and select one codeword from a predetermined codebook corresponding to the rank based on a predetermined criterion; a feedback module, configured to feed back an index of the selected codeword and the rank;

Each column of the second matrix includes a first half-length vector corresponding to a first polarization direction and a second half-length vector corresponding to a second polarization direction, the first half-length vector representing a relative A beam offset of a matrix, the second half-length vector representing a beam offset relative to the first matrix, an inter-polarization beam offset of the second polarization direction relative to the first polarization direction, and a phase offset.

7. The apparatus of claim 6, wherein the first set or the second set is an empty set.

8. The apparatus according to claim 6, wherein the downlink multi-antenna uses a cross-polarization linear array.

9. The apparatus of claim 6, wherein the downlink multi-antenna uses a uniform linear array.

10. The apparatus according to claim 6, wherein when the rank is 2, the second column of the second matrix is further distinguished from the first column by a differential beam offset factor and a differential phase shift factor. .

1 1. A user equipment for a multiple input multiple output system comprising the apparatus of any of claims 5-10.