CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from Chinese Patent Application No. 202110078245.6, filed on Jan. 21, 2021. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present application relates to communication technologies, and more particularly to an omnidirectional beamforming method.

BACKGROUND

Massive MIMO (multiple-input multiple-output) plays a key role in realizing the commercialization of the fifth generation technology (5G). In order to realize the commercialization of the massive MIMO, it is preferable to arrange the antennas in a uniform rectangular array. For base stations deployed with a uniform rectangular antenna array, how to realize the omnidirectional transmission of common signals is a key factor to improve the overall network performance. Therefore, it is urgent to solve the problem that how the base station realizes the omnidirectional transmission of common signals under the uniform rectangular antenna array.

SUMMARY

An object of the present disclosure is to provide an omnidirectional beamforming method, to solve the technical problem in the prior art that the base station cannot realize the omnidirectional transmission of common signals under a uniform rectangular antenna array.

The technical solutions of the present disclosure are described as follows.

In a first aspect, the present disclosure provides an omnidirectional beamforming method, comprising:performing a space-time block coding on a data stream to be sent, to obtain a coded data stream;constructing omnidirectional beamforming matrices corresponding to a uniform rectangular antenna array through a pair of Golay complementary matrices or four autocorrelation complementary matrices;wherein the uniform rectangular antenna array consists of L×M antennas; L is the number of rows of the uniform rectangular antenna array; M is the number of columns of the uniform rectangular antenna array; an array response vector of the uniform rectangular antenna array at a spatial angle of (φ,θ) is calculated as follows:

[A⁡(φ,θ)]l⁢m=e-jλ2⁢π¯⁡(l-1)⁢dy⁢sin⁢⁢φ⁢⁢sin⁢⁢θ-jλ2⁢π¯⁡(m-1)⁢dx⁢sin⁢φ⁢cos⁢θ,⁢for⁢⁢l=1,2,…⁢,L;m=1,2,…⁢,M;θ∈[0,2⁢π];φ∈[0,π];wherein [A(φ,θ)]lmrepresents the array response vector of the uniform rectangular antenna array; the array response vector is a response capability of the antennas in the uniform rectangular antenna array to an incoming wave in a certain direction; a spatial rectangular coordinate system is established, wherein a coordinate origin is a point of a plane where the uniform rectangular antenna array is located; the plane where the uniform rectangular antenna array is located is a xoy plane; and a z-axis is a normal vector of the plane where the uniform rectangular antenna array is located; φ represents an angle between a transmission direction of a signal to be sent and the z-axis in the spatial rectangular coordinate system; θ represents an angle between a projection of the transmission direction of the signal to be sent on the xoy plane and an x-axis in the spatial rectangular coordinate system; λ represents a wavelength of the signal to be sent; dxrepresents a distance between two adjacent antennas in the uniform rectangular antenna array in a direction of the x-axis; and dyrepresents a distance between two adjacent antennas in the uniform rectangular antenna array in a direction of a y-axis;assuming that an omnidirectional beamforming matrix set formed by performing beamforming on the uniform rectangular antenna array is {Wn}n=1N; wherein Wn∈L×M; an autocorrelation of the {Wn}n=1Nis calculated as follows:

RWn⁡(ς,τ)=∑l=1L⁢∑m=1M⁢Wn⁡(l,m)⁢Wn*⁡(l+ς,m+τ),⁢-L+1≤ς≤L-1,-M+1≤τ≤M-1;

wherein ç represents a translation in the direction of they-axis; τ represents a translation in the direction of the x-axis; and (⋅)*represents a conjugation;

the omnidirectional beamforming matrix set {Wn}n=1Nsatisfies the following equation:
Σn=1NRWn(ç,τ)=LMN·δ(ç)δ(τ);wherein the omnidirectional beamforming matrix set {Wn}n=1Nis autocorrelation complementary matrices (L,M,N)-ACM; δ(ç) and δ(τ) are both a Kronecker delta functions

δ⁡(ς)={1⁢ς=00⁢ς≠0;
when N=2, (L,M,N)-ACM is a pair of Golay complementary matrices; andperforming beamforming on the coded data stream through the omnidirectional beamforming matrices, to generate the signal to be sent of the uniform rectangular antenna array.

In an embodiment, the omnidirectional beamforming matrices are shown as follows:

W1=(a⁢cTb⁢dT),W2=(-a⁢d~Tb⁢c~T)∈ℂL×M;

wherein half of the number of the rows L/2 and the number of the columns M of the uniform rectangular antenna array are both complex Golay numbers; W1and W2are a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of L/2; and a sequence c and a sequence d are a pair of Golay complementary sequences with a length of M.

In an embodiment, the omnidirectional beamforming matrices are shown as follows:
W1=(caT,dbT),W2=(−{tilde over (d)}aT,{tilde over (c)}bT)∈L×M;

wherein the number of the rows L and half of the number of the columns M/2 of the uniform rectangular antenna array are both complex Golay numbers; W1and W2are a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of M/2; a sequence c and a sequence d are a pair of Golay complementary sequences with a length of L; and ({tilde over (⋅)}) represents conjugation and flip.

In an embodiment, the omnidirectional beamforming matrices are shown as follows:
W1=acT, W2=adT, W3=bcT, W4=bdT∈L×M;

wherein the number of the rows L and the number of the columns M of the uniform rectangular antenna array are both complex Golay numbers; W1, W2, W3and W4are four autocorrelation complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of L; and a sequence c and a sequence d are a pair of Golay complementary sequences with a length of M.

In an embodiment, the signal to be sent is shown as follows:
X(t)Σn=1NWnsn(t)∈L×M;

wherein X(t) is the signal to be sent; an integer t is an index of a time domain; Wn∈L×Mrepresents a spatial beamforming weight of sn(t); wherein n=1, . . . , N, and N is a positive integer.

In a second aspect, the present disclosure further provides another omnidirectional beamforming method, comprising:

constructing a first beamforming matrix corresponding to a first polarized antenna sub-array; performing a beamforming on a data stream to be sent through the first beamforming matrix, to obtain a first polarized signal; and sending the first polarized signal via the first polarized antenna sub-array; and

constructing a second beamforming matrix corresponding to a second polarized antenna sub-array; performing a beamforming on the data stream to be sent through the second beamforming matrix, to obtain a second polarized signal; and sending the second polarized signal via the second polarized antenna sub-array;

wherein the first polarized antenna sub-array and the second polarized antenna sub-array are in an orthogonal relationship.

In an embodiment, the first polarized antenna sub-array is a left-polarized antenna sub-array; the first beamforming matrix is a left-polarized beamforming matrix; the second polarized antenna sub-array is a right-polarized antenna sub-array; and the second beamforming matrix is a right-polarized beamforming matrix; or

the first polarized antenna sub-array is a horizontally polarized antenna sub-array; the first beamforming matrix is a horizontally polarized beamforming matrix; the second polarized antenna sub-array is a vertically polarized antenna sub-array; and the second beamforming matrix is a vertically polarized beamforming matrix.

In an embodiment, the left-polarized beamforming matrix corresponding to the left-polarized antenna sub-array and the right-polarized beamforming matrix corresponding to the right-polarized antenna sub-array are constructed through a pair of Golay complementary matrices; wherein the first beamforming matrix is a left-polarized beamforming matrix, and the second beamforming matrix is a right-polarized beamforming matrix.

In an embodiment, the left-polarized beamforming matrix and the right-polarized beamforming matrix are shown as follows:

Wleft=(a⁢cTb⁢dT),Wright=(-a⁢d~Tb⁢c~T)∈ℂL2×M;

wherein Wleftis the left-polarized beamforming matrix; Wrightis the right-polarized beamforming matrix; half of the number of rows L/4 and the number of the columns M of the left-polarized antenna sub-array and half of the number of rows L/4 and the number of columns M of the right-polarized antenna sub-array are both complex Golay numbers; Wleftand Wrightare a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of L/4; a sequence c and a sequence d are a pair of Golay complementary sequences with a length of M; and ({tilde over (⋅)}) represents conjugation and flip.

In an embodiment, the left-polarized beamforming matrix and the right-polarized beamforming matrix are as follows:

Wleft=(a⁢cTb⁢dT),Wright=(-a⁢d~Tb⁢c~T)∈ℂL×M2;

wherein Wleftis the left-polarized beamforming matrix; Wrightis the right-polarized beamforming matrix; half of the number of rows L/2 and the number of columns M/2 of the left-polarized antenna sub-array and the right-polarized antenna sub-array are both complex Golay numbers; Wleftand Wrightare a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of L/2; a sequence c and a sequence d are a pair of Golay complementary sequences with a length of M/2; and ({tilde over (⋅)}) represents conjugation and flip.

In an embodiment, the left-polarized beamforming matrix and the right-polarized beamforming matrix are as follows:

Wleft=(c⁢aT,d⁢bT),Wright=(-d~⁢aT,c~⁢bT)∈ℂL2×M;

wherein Wleftis the left-polarized beamforming matrix; Wrightis the right-polarized beamforming matrix; the number of rows L/2 and half of the number of columns M/2 of the left-polarized antenna sub-array and the number of rows L/2 and half of the number of columns M/2 of the right-polarized antenna sub-array are both complex Golay numbers; Wleftand Wrightare a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of M/2; a sequence c and a sequence d are a pair of Golay complementary sequences with a length of L/2; and ({tilde over (⋅)}) represents conjugation and flip.

In an embodiment, the left-polarized beamforming matrix and the right-polarized beamforming matrix are shown as follows:

Wleft=(c⁢aT,d⁢bT),Wright=(-d~⁢aT,c~⁢bT)∈ℂL×M2;

wherein Wleftis the left-polarized beamforming matrix; Wrightis the right-polarized beamforming matrix; the number of rows L and half of the number of columns M/4 of the left-polarized antenna sub-array and the number of rows L and half of the number of columns M/4 of the right-polarized antenna sub-array are both complex Golay numbers; Wleftand Wrightare a pair of Golay complementary matrices; a sequence a and a sequence b are a pair of Golay complementary sequences with a length of M/4; a sequence c and a sequence d are a pair of Golay complementary sequences with a length of L; and ({tilde over (⋅)}) represents conjugation and flip.

Compared to the prior art, the present invention has the following beneficial effects.

In the omnidirectional beamforming method of the present disclosure, the coded data stream is obtained by performing a space-time block coding on the data stream to be sent; the omnidirectional beamforming matrices corresponding to the uniform rectangular antenna array are constructed; and the beamforming is performed on the coded data stream through the omnidirectional beamforming matrices, to generate a signal to be sent of the uniform rectangular antenna array. Through the arrangement in the present disclosure, the omnidirectional transmission of common signals can be realized, so that the signals to be sent have the same signal energy distribution in space, that is, the signals to be sent at any point in the space has the same energy, thereby improving the performance of the overall network.

