CN103236878B - A kind of coordinates beam shaping method receiving vector estimation based on maximum-ratio combing - Google Patents

Abstract

The present invention provides a coordinated beamforming method based on maximum ratio combining receiving vector estimation: each cooperative base station uses the maximum ratio combining method to estimate the serving user's Receive the beamforming vector, and then share the estimated value of the received beamforming vector of each serving user among the cooperative base stations; each cooperative base station uses the shared estimated value of the received beamforming vector, and maximizes the signal-to-noise ratio as a criterion to design The transmit beamforming vector at the current moment; the present invention obtains the estimated value of the receiving beamforming vector of the interfering user by sharing a small amount of information among the cooperative base stations, and then designs the transmitting beamforming vector based on the criterion of maximizing the SLNR according to the estimated value, Compared with the traditional coordinated beamforming scheme based on maximizing the SLNR criterion, the performance is significantly improved, and the system overhead is small, and it can be implemented in a distributed manner at each cooperative base station.

Description

A Coordinated Beamforming Method Based on Maximum Ratio Combining Receive Vector Estimation

technical field

The invention belongs to the technical field of coordinated multipoint transmission in a wireless communication system, and relates to a coordinated beamforming method based on estimating a receiving beamforming vector.

Background technique

The joint processing technology in coordinated multi-point transmission needs to share data and channel state information among the nodes participating in the cooperation. Although it can maximize system performance, it has high requirements on the throughput and delay of the backhaul link (Backhaul) , and has strict requirements on symbol synchronization, and it is difficult to implement under the existing network architecture and standards, so it is difficult to implement. Coordinated beamforming is an important branch of coordinated multipoint transmission technology. It provides a compromise between Backhaul overhead and system performance. Compared with joint processing, coordinated beamforming only needs to share channel state information at the base station. , which can coordinate and suppress interference between cells through methods such as transceiver beam optimization, power control, and user scheduling, so it is easier to implement under the existing network architecture. When the number of users in the system is large enough, the system performance can be significantly improved through this interference coordination method.

Existing coordinated beamforming schemes for Multiple Input Multiple Output (MIMO) systems are mainly divided into self-interested schemes, altruistic schemes, and selfish-altruistic compromise schemes. In the self-interested scheme, the base station transmitter ignores the interference to other users and maximizes its own utility function. This scheme has good performance when the Signal-to-Noise Ratio (SNR) is small and the noise is dominant, but the performance deteriorates when the SNR is large and the interference is severe. In an altruistic scheme, the base station transmitter minimizes interference to other users. This solution can effectively suppress the interference between users, especially when the SNR is relatively large, that is, when the interference is dominant, good performance can be obtained. However, this scheme is inefficient at low to medium SNRs. The self-interest-altruism compromise scheme will maximize the self-utility function and minimize the interference to other users, so as to achieve the optimal system performance. It has been proved in the literature that if the Signal-to-Interference-and-Noise Ratio (SINR) is maximized as the criterion, the designed transmit beamforming vector is a linear combination of the self-interested and altruistic schemes. If the maximum Signal-to-Leakage-and-Noise Ratio (SLNR) is taken as the criterion, it can be seen from the objective function that this also requires a compromise between self-interest and altruism. The above schemes can be divided into two types: the coordinated beamforming scheme considering the receiving vector and the coordinated beamforming scheme not considering the receiving vector. The performance of the scheme considering the receiving vector is significantly improved compared with the scheme not considering the receiving vector. But the overhead of feedback overhead and information sharing is much larger than the overhead of the scheme without considering the receiving vector.

The traditional transmit beamforming vector design scheme based on the SLNR criterion can be implemented in a distributed manner at each base station, but because this design method does not consider the impact of the receive vector on performance, the system performance is poor. If the receiving vectors of each base station are considered, all cooperative base stations need to share all the channel state information, which will lead to a large overhead of the X2 interface, and it is relatively difficult to implement.

Contents of the invention

The purpose of the present invention is to provide a coordinated beamforming method based on maximum ratio combining receiving vector estimation.

In order to achieve the above object, the present invention adopts the following technical solutions.

The coordinated beamforming method includes the following steps:

In the first step, each cooperative base station estimates the receiving beamforming vector of the serving user in the way of maximum ratio combining according to the known channel state information and the transmitting beamforming vector at the previous moment, and then shares the respective serving users among the cooperative base stations The received beamforming vector estimate of ;

In the second step, each cooperative base station calculates the transmit beamforming vector at the current moment by using the estimated value of the receive beamforming vector obtained through sharing and maximizing the signal-to-leakage-to-noise ratio.

The specific steps of the coordinated beamforming method are as follows:

Consider a coordinated multi-point transmission system, which contains M cooperative base stations and M users, and the i-th user is the service user of the i-th base station, i=1,2,...,M, and the base stations use coordinated beams The shape-forming method serves users. Let PL _ji represent the path loss from the i-th base station to the j-th user, and use H _ji to represent the channel matrix from the i-th base station to the j-th user, and assume that the elements of H _ji are mutually Independent and subject to a complex Gaussian distribution with zero mean unit variance, the transmit power of the i-th base station is P _i , the receiving noise of each user is n _i , and the noise power is σ ² , and each base station knows all users in the cooperative set The channel matrix;

Step 1: At the transmitting end, the base station first calculates the estimated value of the receiving beamforming vector of the serving user at the previous moment based on the maximum ratio combination criterion based on the channel state information and the transmitting beamforming vector at the previous moment: n-1 means the previous moment;

Step 2: Each base station shares the estimated value of the received beamforming vector of the serving user with the cooperative base station, and after sharing, each base station obtains the estimated value of the received beamforming vector of all users served by the coordinated base station ${\hat{v}}_i^{(\mathrm{no}-1)},i=\mathrm{1,2},...,m;$

Step 3: Each base station calculates the transmit beam of the base station at the current moment based on the estimated value of the received beamforming vector of the serving user and the estimated value of the received beamforming vector of the interfering user shared by the cooperative base station with the goal of maximizing the signal-to-leakage-to-noise ratio Shaped vectors, as shown in the following formula:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}$

in, ${\mathrm{\&Phi;}}_i^{(\mathrm{no}-1)}=\underset{j\&NotEqual;i}{\mathrm{\&Sigma;}}{P}_{i}P{L}_{\mathrm{the\; ji}}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)h}{\hat{v}}_j^{(\mathrm{no}-1)}{\hat{v}}_j^{(\mathrm{no}-1)h}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)}+{\mathrm{\&sigma;}}^2{I}_{N_t},$ Represents N _t ×N _t dimensional unit matrix, n represents the current moment;

Step 4: After the third step, the base station sends the beam-formed signal to the user.

The beneficial effects of the present invention are reflected in:

The present invention obtains the estimated value of the received beamforming vector of the interfering user by sharing a small amount of information among cooperative base stations, and then designs the transmitting beamforming vector based on the estimated value based on the criterion of maximizing SLNR. Compared with the traditional coordinated beamforming scheme based on maximizing the SLNR criterion, the performance of this scheme is significantly improved, and the system overhead is small, and it can be implemented in a distributed manner at each cooperative base station.

Description of drawings

Figure 1 is a schematic diagram of a coordinated multi-point transmission system, in which: a solid line represents a useful channel; a dotted line represents an interference channel; BS represents a base station; MS represents a user;

Fig. 2 is a flow chart of the present invention;

Figure 3 is a comparison of user average spectral efficiency of different schemes under a static channel;

Figure 4 shows the comparison of user average spectral efficiency of different schemes under slow-varying channels.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

The main idea of the coordinated beamforming method based on the maximum ratio combined receiving vector estimation proposed by the present invention is as follows: in the first step, each cooperative base station uses the maximum ratio The receiving beamforming vector of the serving user is estimated in a combined way, and shared among the cooperative base stations; in the second step, each cooperative base station is based on the estimated value of the receiving beamforming vector of the interfering user obtained by sharing to maximize the signal-to-noise-to-noise ratio ( SLNR) as a criterion to calculate the transmit beamforming vector at the current moment.

The specific implementation plan is as follows:

Consider the system shown in Figure 1, the system contains M cooperative base stations and M users, each base station serves 1 user, and the i-th user is the service user of the i-th base station, i=1,2,. . . . , M, the base station serves users by means of coordinated beamforming. Each base station is equipped with N _t antennas, and each user is equipped with N _r antennas. PL _ji and H _ji represent the path loss and channel matrix (N _r ×N _t dimensions) from the i-th base station to the j-th user respectively, and assume that each element of H _ji is independent of each other and obeys a complex Gaussian distribution with zero mean unit variance . The transmitting power of the i-th base station is P _i , the receiving noise of each user is n _i , and the noise power is σ ² . Assume that each base station knows its channel matrix to all users in the cooperating set, that is, the i-th base station knows H _ji (j=1,2,...,M). The received signal y _i of the i-th user can be expressed as:

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\mathrm{<span\; class="notranslate">\; P</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}\mathrm{<span\; class="notranslate">\; P</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1), x _i is the transmission signal of the i-th base station, w _i (N _t ×1 dimension, ‖w _i ‖=1) represents the transmission beamforming vector of the i-th base station, v _i (N _r ×1 dimension, ‖v _i ‖=1) represents the receiving beamforming vector of the i-th user, and the superscript H represents the conjugate transpose. The receiving SINR of the i-th user can be obtained from formula (1), as shown in formula (2):

${\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

After considering the receive beamforming vector, the SNR of the i-th base station can be expressed as:

${\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The total spectral efficiency of the system and the average spectral efficiency per user are shown in formula (4) and formula (5) respectively:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The technical means of the coordinated beamforming scheme based on maximum ratio combining receiving vector estimation proposed by the present invention are as follows:

Perform the following four steps on the base station transmitter:

Step 1: At the transmitting end, the base station first calculates the receiving beamforming of the serving user at the previous moment based on the maximum ratio combining (MRC) criterion based on the channel state information at the previous moment (n-1th moment) and the transmitting beamforming vector Vector estimates:

Step 2: Each base station shares the estimated value of the received beamforming vector of the serving user with the cooperative base station, and after sharing, each base station obtains the estimated value of the received beamforming vector of all users served by the coordinated base station, namely:

Step 3: Each base station calculates the current time of the base station with the goal of maximizing the signal-to-leakage-to-noise ratio (SLNR) based on the estimated value of the received beamforming vector of the serving user and the estimated value of the received beamforming vector of the interfering user shared by the cooperative base station (time n) transmit beamforming vector. As shown in the following formula, the objective function of the i-th base station is:

$\underset{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; SLNR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{<span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}{<span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Right now:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\underset{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}}\frac{{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}{{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

The solution to this optimization problem is in, ${\mathrm{\&Phi;}}_i^{(\mathrm{no}-1)}=\underset{j\&NotEqual;i}{\mathrm{\&Sigma;}}{P}_i{\mathrm{PL}}_{\mathrm{the\; ji}}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)h}{\hat{v}}_j^{(\mathrm{no}-1)}{\hat{v}}_j^{(\mathrm{no}-1)h}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)}+{\mathrm{\&sigma;}}^2{I}_{N_t},$ Indicates N _t ×N _t dimensional unit matrix;

Step 4: The base station sends the beamformed signal to the user.

On the receiving end do the following:

Step 1: The user calculates the receiving beamforming vector at the current time n by using the Minimum Mean-Square Error (MMSE) criterion that maximizes the receiving SINR, namely:

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Psi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Psi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

in ${\mathrm{\&Psi;}}_i^{\left(\mathrm{no}\right)}=\underset{j\&NotEqual;i}{\mathrm{\&Sigma;}}{P}_j{\mathrm{PL}}_{\mathrm{ij}}{h}_{\mathrm{ij}}^{\left(\mathrm{no}\right)}{w}_j^{\left(\mathrm{no}\right)}{w}_i^{\left(\mathrm{no}\right)h}{h}_{\mathrm{ij}}^{\left(\mathrm{no}\right)}+{\mathrm{\&sigma;}}^2{I}_{N_r},$ Represents N _r ×N _r dimensional identity matrix;

The second step: the user receives the transmitted signal according to the received beamforming vector calculated in the first step, and the received signal y _i of the i-th user is expressed by (1).

Below in conjunction with Fig. 2, the flow process of the present invention is further described:

1. Initialization:

a)n=1;

b) Each base station initializes the transmit beamforming vector according to the traditional SLNR scheme it is

and The largest generalized eigenvalue corresponding to

The eigenvectors of

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\underset{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; max</span>}\mathrm{<span\; class="notranslate">\; the\; gene</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; eigenvector</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>\frac{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; the\; ji</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

c) calculate and shared among cooperative base stations;

2. Transmitter:

a) Each base station calculates the transmit beamforming vector of the base station at the current moment:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}<span\; class="notranslate">\; ,</span>$

in: ${\mathrm{\&Phi;}}_i^{(\mathrm{no}-1)}=\underset{j\&NotEqual;i}{\mathrm{\&Sigma;}}{P}_i{\mathrm{PL}}_{\mathrm{the\; ji}}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)h}{\hat{v}}_j^{(\mathrm{no}-1)}{\hat{v}}_j^{(\mathrm{no}-1)h}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)}+{\mathrm{\&sigma;}}^2{I}_{N_t},$ Indicates N _t ×N _t dimensional unit matrix;

b) The transmitter of the base station transmits the beamformed signal to the service user according to the designed transmit beamforming vector;

c) Each base station calculates the estimated value of the receiving beamforming vector at the current moment and shares it with each cooperative base station; ${\hat{v}}_i^{\left(\mathrm{no}\right)}=\frac{h_i^{\left(\mathrm{no}\right)}{w}_i^{\left(\mathrm{no}\right)}}{\left|\right|h_i^{\left(\mathrm{no}\right)}{w}_i^{\left(\mathrm{no}\right)}\left|\right|};$

3. Receiver:

a) The user uses formula (8) to calculate the receive beamforming vector;

b) The user uses the designed receiving beamforming vector to receive the signals sent by each base station;

4. n←n+1; repeat steps 2-4 until the communication ends.

Simulation effect of the present invention is as follows:

Consider a scenario of seven cells and seven users, the number of antennas per base station is 4, and the number of antennas per user is 2. Assuming that the path loss PL _ii =1 from each base station to its serving users, The path loss between each base station and the interfering user is a random number between 0 and 1, that is, PL _ji =rand(1), i≠j. The channel model adopts the Rayleigh channel, the signal-to-noise ratio SNR=10, simulates 20 time slots, and assumes that the transmit power of each base station is equal. 10,000 independent simulations were performed for both the static channel and the slowly varying channel.

Comparing the present invention with the traditional SLNR-based (T-SLNR) coordinated beamforming scheme that does not consider the receiving vector and the SLNR-based (JTR-CB) coordinated beamforming scheme that considers the receiving vector, each time slot Figure 3 and Figure 4 show the average spectral efficiency of users. It can be seen from Fig. 3 and Fig. 4 that under the two channel conditions, the performance of the scheme of the present invention is significantly improved compared with the coordinated beamforming scheme of T-SLNR, although there is still a certain gap compared with the JTR-CB scheme. But the required information exchange is much smaller than the JTR-CB scheme, so it is more feasible than the JTR-CB scheme. In the JTR-CB scheme, each cooperative base station needs to share all channel state information (ie j=1,2,...,M), in order to calculate the receiving beamforming vectors of all users at the previous moment, and thus estimate the transmitting beamforming vectors of the base station at the current moment. However, in the solution of the present invention, each cooperative base station only needs to share the receiving vector estimated by the base station based on the MRC criterion (ie ), the amount of information sharing is only that of the JTR-CB scheme In addition, it can also be seen from FIG. 3 and FIG. 4 that the solution of the present invention has a faster convergence speed, so it can adapt to scenarios where channels change quickly. See Table 1 and Table 2 for the average spectrum efficiency of 20 time slots in each scheme. As can be seen from Table 1 and Table 2, compared with the T-SLNR scheme, the average spectral efficiency of each user in the two channel environments has been improved by 22.24% and 24.70%, respectively, and only 10.33% and 24.70% lower than the JTR-CB scheme. 10.44%. Table 1 User average spectral efficiency of different static channel schemes

Table 2 User average spectral efficiency of different schemes for slowly varying channels

Claims (2)

1. A method for coordinating beamforming based on maximum ratio combined reception vector estimation, characterized in that: the method for coordinating beamforming comprises the following steps: In the first step, each base station initializes the transmit beamforming vector according to the scheme of maximizing the signal-to-leakage-to-noise ratio, and each cooperative base station uses the maximum ratio combining method to estimate the serving beamforming vector according to the known channel state information and the transmit beamforming vector at the previous moment The receiving beamforming vector of the user, and then share the estimated value of the receiving beamforming vector of the respective serving user among the cooperative base stations; In the second step, each cooperative base station calculates the transmit beamforming vector at the current moment by using the estimated value of the receive beamforming vector obtained through sharing and maximizing the signal-to-leakage-to-noise ratio. 2. A kind of coordinated beamforming method based on maximum ratio combining receiving vector estimation according to claim 1, characterized in that: Consider a coordinated multi-point transmission system, which contains M cooperative base stations and M users, and the i-th user is the service user of the i-th base station, i=1,2,...,M, and the base stations use coordinated beams The shape-forming method serves users. Let PL _ji represent the path loss from the i-th base station to the j-th user, and use H _ji to represent the channel matrix from the i-th base station to the j-th user, and assume that the elements of H _ji are mutually Independent and subject to a complex Gaussian distribution with zero mean unit variance, the transmit power of the i-th base station is P _i , the receiving noise of each user is n _i , and the noise power is σ ² , and each base station knows all users in the cooperative set The channel matrix; Each base station calculates the transmit beamforming vector of the base station at the current moment based on the estimated value of the received beamforming vector of the serving user and the estimated value of the received beamforming vector of the interfering user shared by the coordinated base station, with the goal of maximizing the signal-to-leakage-to-noise ratio. As shown in the following formula: ${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}$ in, ${\mathrm{\&Phi;}}_i^{(\mathrm{no}-1)}=\underset{j\&NotEqual;i}{\mathrm{\&Sigma;}}{P}_i{\mathrm{PL}}_{\mathrm{the\; ji}}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)h}{\hat{v}}_j^{(\mathrm{no}-1)}{\hat{v}}_j^{(\mathrm{no}-1)h}{h}_{\mathrm{the\; ji}}^{(\mathrm{no}-1)}+{\mathrm{\&sigma;}}^2{I}_{N_t},$ represents N _t ×N _t dimensional unit matrix, n represents the current moment, Indicates the estimated value of the receiving beamforming vector of the serving user at the previous moment; Then, the base station sends the beamformed signal to the user.