CN102647247B

CN102647247B - One transmits preliminary treatment sending method and device

Info

Publication number: CN102647247B
Application number: CN201110044238.0A
Authority: CN
Inventors: 宁迪浩; 朱登魁; 肖华华; 鲁照华
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2015-08-12
Anticipated expiration: 2031-02-22
Also published as: WO2012113185A1; CN102647247A

Abstract

The invention discloses one to transmit preliminary treatment sending method and device, the method is applicable to comprise and participates in the first transmitting terminal of cooperation and the wireless communication system of the second transmitting terminal, comprising: the first transmitting terminal and the second transmitting terminal are respectively according to the kth user's down channel coefficient matrix H measured or feedback obtains _{1, k}and H _{2, k}, calculate precoding vector W independently optimum for a kth user separately _{1, k}and W _{2, k}; Phase rotating is not done to transmitting of the first transmitting terminal, i.e. phase rotation matrix R ₁the final precoding vectors of the=1, first transmitting terminal is calculate the phase rotation matrix R of the second transmitting terminal ₂, according to the phase rotation matrix R of the second transmitting terminal ₂, calculate the final precoding vectors of the second transmitting terminal e ^{j θ}for phase rotation coefficient; According to final precoding vectors with transmitting as the process of emitting side process weights, be multiplied by respective original transmitted signal, to be sent by antenna as finally transmitting.The present invention efficiently utilizes multicast communication technology, reduces the interference of cell edge, improves cell edge spectrum efficiency.

Description

Transmitting signal preprocessing and transmitting method and device

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a method and a device for preprocessing and sending a transmitted signal.

Background

With the continuous development of multi-antenna communication technology, people find that the same-frequency networking in the true sense is not realized in the practices of OFDMA technical standard 802.16e/m, LTE and the like for the current cellular network topological structure, so that the isolated cell has higher spectrum efficiency and lower networking efficiency. The average throughput of the cell is obviously reduced in addition to the problem of cell edge rate in the same-frequency networking. Co-frequency networking is one of the most major problems commonly faced by the current OFDMA standards WiMAX and LTE. The multi-point transmission adopts the technical measures that the multi-point transmission mode of the same frequency is carried out simultaneously through different radio frequency access points (RRUs) in the base station, the Base Station (BS), Relay stations (Relay) belonging to the base station and the like, the cell edge interference is reduced, the cell edge spectrum efficiency is improved, and the effective coverage is increased. The single-site multi-antenna technology or the non-multipoint transmission technology can increase the data transmission rate, but the performance of the cell edge cannot be obviously improved, and the multi-antenna technology has a plurality of working modes such as multiplexing and Beamforming universality which are not good; and through multipoint cooperation, virtual MIMO (namely VMIMO) can be formed, the cell edge performance can be increased, and the requirement on a terminal is not high.

The problem of multiple neighboring base stations, which may be Base Stations (BS), Relay stations (Relay), pico base stations (femeto) communicating with multiple user terminals on the same time-frequency resource, we refer to it as a multipoint transmission technique (as shown in fig. 1), which includes a coordinated multipoint transmission (Comp) technique and a Distributed precoding technique (Distributed precoding Scheme: DPS), wherein the coordinated multipoint transmission includes Coordinated Beamforming (CB) and joint processing technique (JP).

Although the joint processing technology can obtain excellent data transmission performance, each base station participating in cooperation needs to acquire channel information from each user to all the cooperative base stations, the transmission amount of the information is very large, which is a great challenge for an uplink channel and an interface between the base stations, so that in practice, people often return to a suboptimal data transmission mode, that is, each cooperative base station only acquires channel information from all users to itself (so-called Local CSI), and then performs optimal precoding processing by using the information, so that interference avoidance and maximum transmission are expected, which is the idea of distributed precoding.

For a distributed precoding system, if there are N cooperative base stations forming a cooperative set a and a scenario in which data is transmitted for K users at the same time, data received by user K may be represented as:

<math> <mrow> <msub> <mi>Y</mi> <mi>k</mi> </msub> <mo>=</mo> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msub> <mi>H</mi> <mrow> <mi>i</mi> <mo>,</mo> <mi>k</mi> </mrow> </msub> <msub> <mi>W</mi> <mrow> <mi>i</mi> <mo>,</mo> <mi>k</mi> </mrow> </msub> <msub> <mi>s</mi> <mi>k</mi> </msub> <mo>+</mo> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <munderover> <mi>Σ</mi> <munder> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>j</mi> <mo>&NotEqual;</mo> <mi>k</mi> </mrow> </munder> <mi>K</mi> </munderover> <msub> <mi>H</mi> <mrow> <mi>i</mi> <mo>,</mo> <mi>k</mi> </mrow> </msub> <msub> <mi>W</mi> <mrow> <mi>i</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>s</mi> <mi>j</mi> </msub> <mo>+</mo> <msub> <mi>n</mi> <mi>k</mi> </msub> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

whereinRepresenting the channel coefficient matrix from the ith base station to the kth user,representing the precoding matrix from the ith base station to the kth user, d_kRepresents the number of data streams corresponding to user k, whereinA desired signal representing the user k is indicated,representing interference between multiple users, n_kRepresenting the antenna noise vector.

The key to obtaining excellent reception performance for such a distributed precoding system is the expected received signal item for user kWhether coherency merging can be performed because of H_i,kW_i,kAre generally complex coefficient vectors that when directly superimposed will most likely cancel each other out, causing the gain to suffer or decrease even by 0, so only if H is_i,kW_i,kThe combining gain brought by multiple base stations can be really obtained when the phases are the same.

A specific example is used below to explain what is the coherency merge. Taking a two-dimensional real vector as an example, for a real vector, the equivalent vector has the opposite direction, i.e.So for the two vectors shown in fig. 2Andto maximizeEquivalence relations can be utilized whenAndwhen the included angle of the angle is an acute angle,maximum, whenAndwhen the included angle is an obtuse angle, it is obviousMaximum, so that the maximum value is

Therefore, in order for user k to coherently combine the desired signal components in the received signal at the receiving side, the base station side needs to rotate the phase of the transmitted signal, and thus equation (1) becomes

Here, ,representing the phase rotation matrix of the ith base station. For a single stream transmission system, H in equation (2)_i,kW_i,kThe result of the multiplication is a complex number, when the rotation matrix isDegenerated into a unit modulus complex number e^jθ。

To sum up, in the downlink distributed precoding, in a single stream transmission scenario, the phase rotation is performed at the base station side to enable the receiving side to perform the desired interference combining, and the key is to rotate the matrix, and how to obtain the optimal rotation matrix becomes a problem that needs to be solved urgently at the present stage.

Disclosure of Invention

The invention provides a method and a device for preprocessing and sending a transmitting signal, which are used for solving the problem of related combination in a multipoint transmission technology at least so as to finally solve the problem of reducing co-channel interference in the transmission process of a system.

According to an aspect of the present invention, there is provided a transmission signal preprocessing transmission method, which is applied to a wireless communication system including a first transmitting end and a second transmitting end participating in cooperation, and includes:

the first sending end and the second sending end respectively obtain a k user downlink channel coefficient matrix H according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k；

The transmitted signal of the first transmitting end is not subjected to phase rotation, i.e. the phase rotation matrix R₁1, the final precoding vector of the first transmitting end is

Calculating a phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₂Calculating the final precoding vector of the second transmitting endWherein,is a phase rotation factor;

according to the final precoding vectorAndand processing the transmitting signals as the processing weight of the transmitting side, multiplying the transmitting signals by respective original transmitting signals, and sending the signals as final transmitting signals through an antenna.

According to an aspect of the present invention, a transmission signal preprocessing and transmitting method is provided, which is applied to a wireless communication system including a first transmitting end, a second transmitting end, and a third transmitting end participating in cooperation, and includes:

the first sending end, the second sending end and the third sending end respectively obtain a k user downlink channel coefficient matrix H according to measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k；

Calculating phase rotation matrix R of the second transmitting end and the third transmitting end₂、R₃According to the phase rotation matrix R of the second transmitting end and the third transmitting end respectively₂、R₃Calculating the final pre-coding vectors of the second and third transmitting ends

In addition, the present invention also provides a transmission signal preprocessing and transmitting apparatus, which is suitable for a wireless communication system including a first transmitting end and a second transmitting end participating in cooperation, and includes:

precodingA vector calculation module for obtaining the k-th user downlink channel coefficient matrix H according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k；

A first sending end final pre-coding vector calculation module for determining the final pre-coding vector of the first sending end as

A final pre-coding vector calculation module for calculating the phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₃Calculating the final precoding vector of the second transmitting end

A data transmission module for transmitting the final precoding vectorAndand processing the transmitting signals as the processing weight of the transmitting side, multiplying the transmitting signals by respective original transmitting signals, and sending the signals as final transmitting signals through an antenna.

Further, the present invention provides a transmission signal preprocessing and transmitting apparatus, which is suitable for a wireless communication system including a first transmitting end, a second transmitting end, and a third transmitting end participating in cooperation, and includes:

a precoding vector calculation module for obtaining the k-th user downlink channel coefficient matrix H according to measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k；

A final pre-coding vector calculation module for calculating phase rotation matrix R of the second and third transmitting ends₂、R₃According to the phase rotation matrix R of the second transmitting end and the third transmitting end respectively₂、R₃Calculating the final pre-coding vectors of the second and third transmitting ends

Through the technical scheme, the signals sent by a plurality of sending ends can be effectively coherently combined by the receiving end by acquiring the phase rotation matrix, so that the multipoint transmission technology is effectively utilized, the interference of the cell edge is reduced, the cell edge spectrum efficiency is improved, and the effective coverage area of the cell is increased.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic diagram of a multicast transmission technique;

FIG. 2 is a schematic diagram of coherent combining;

FIG. 3 is a flow chart of the present invention when the number of cooperative base stations is 2;

fig. 4 is a flowchart of a technical solution when the number of cooperative base stations is 3 according to the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Considering that the form and calculation method of the phase rotation matrix are different under the condition that the number of the cooperative base stations is different, the rotation matrix calculation methods in single stream transmission are respectively given when the number of the cooperative base stations is 2 and 3.

The number of cooperative base stations is 2

As shown in fig. 3, when the number of cooperative base stations is 2, the method includes: 1. the first sending end and the second sending end respectively obtain a k user downlink channel coefficient matrix H according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k(ii) a 2. The transmitted signal of the first transmitting end is not subjected to phase rotation, i.e. the phase rotation matrix R₁1, the final precoding vector of the first transmitting end is3. Calculating a phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₂Calculating the final precoding vector of the second transmitting end4. According to the final precoding vectorAndand processing the transmitting signals as the processing weight of the transmitting side, multiplying the transmitting signals by respective original transmitting signals, and sending the signals as final transmitting signals through an antenna.

In the following description, it is assumed that base stations participating in cooperation are base station 1 and base station 2, and the number of users in service in these two cooperation base stations is K.

The following steps are used to calculate the rotation matrix required by the two base stations to transmit to the k-th user. Step 1

The base station 1 and the base station 2 respectively obtain a coefficient matrix H of a downlink channel of a kth user according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k。

Step 2

The transmission signal of the base station 1 is not phase rotated, i.e. the phase rotation matrix R₁The final precoding vector of base station 1 is 1

Step 3

The method 1 for calculating the rotation matrix of the transmission signal of the base station 2 adopts one of the following two methods:

quantising the twiddle factor e using n bits of information^jθAngle theta in (1), i.e. constructing a set of codewords that quantize thetaContains 2 in totalⁿA m code word ofBeta is an arbitrary constant. From the collectionSelecting a code word theta, calculating theta such that the following formula takes the maximum value

In the formula, H_1,kAnd H_2,kThe downlink channel coefficient matrices of base station 1 and base station 2 to user k are respectively represented. The final precoding vector of base station 2 is

The method 2 comprises the following steps:

the phase rotation factor e of the base station 2 is directly calculated using the following formula^jθ

In the formula, H_1,kAnd H_2,kRespectively representing the coefficients of the downlink channels from the base station 1 and the base station 2 to the user k, and the final precoding vector of the base station 2 is

Step 4

The cooperative base station uses the final precoding vector obtained by the calculationAndprocessing the transmit signals as transmit side processing weights, multiplying the respective original transmit signals as final transmit signals, i.e.

P_{i, k} = \tilde{W_{i, k}} s_{k}

Wherein, P_i,kRepresenting the vector of signals that base station i ultimately transmits to user k,is the final precoding vector, s, of the ith base station to the kth user_kIs the original transmitted signal transmitted to the kth user.

The number of cooperative base stations is 3

As shown in fig. 4, when the number of cooperative base stations is 3, the method includes: 1', a first sending end, a second sending end and a third sending end respectively obtain a k user downlink channel coefficient matrix H according to measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k(ii) a 2', the transmitted signal of the first transmitting end is not subjected to phase rotation, namely, a phase rotation matrixThe final precoding vector of the first transmitting end is3', calculating phase rotation matrixes R of a second sending end and a third sending end₂、R₃According to the phase rotation matrix R of the second transmitting end and the third transmitting end respectively₂、R₃Calculating the final pre-coding vectors of the second and third transmitting ends4' according to the final precoding vectorAndand processing the transmitting signals as the processing weight of the transmitting side, multiplying the transmitting signals by respective original transmitting signals, and sending the signals as final transmitting signals through an antenna.

In the following description, it is assumed that base stations participating in cooperation are base station 1, base station 2, and base station 3, and the number of users in service in the three cooperation base stations is K.

The following steps are used to calculate the rotation matrix required by the three base stations to transmit to the k-th user. Step 1

Base station 1, base station 2 and base station 3 are eachObtaining a k user downlink channel coefficient matrix H according to measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k。

Step 2

The transmission signal of the base station 1 is not phase rotated, i.e. the phase rotation matrixThe final precoding vector of base station 1 is

Step 3

The transmitted signals of the base stations 2 and 3 are subjected to calculation of the rotation matrix by one of the following two methods.

The method comprises the following steps:

quantising the twiddle factor e using n bits of information^jθAngle theta in (1), i.e. constructing a set of codewords that quantize thetaContains 2 in totalⁿA m code word ofBeta is an arbitrary constant. From the collectionSelecting two codewords theta₂And theta₃Find θ which maximizes the following equation₂And theta₃

In the formula, H_1,k、H_2,kAnd H_3,kThe downlink channel coefficient matrices of base station 1, base station 2 and base station 3 to user k are respectively represented. The final precoding vector of base station 2 isThe final precoding vector of base station 3 is

The method 2 comprises the following steps:

first, the phase rotation factor of the base station 2 is calculated using the following formula

In the formula, H_1,kAnd H_2,kThe downlink channels to user k are indicated for base station 1 and base station 2, respectively.

Secondly, according to the obtained phase rotation factor of the base station 2The phase rotation factor of the base station 3 is calculated using the following formula

In the formula, H_1,k、H_2,kAnd H_3,kThe downlink channels to user k are indicated for base station 1, base station 2 and base station 3, respectively.

The final precoding vector of base station 2 isThe final precoding vector of base station 3 is

Step 4

P_{i, k} = \tilde{W_{i, k}} s_{k}

The following describes a method and an apparatus for calculating a phase rotation matrix of distributed precoding described in the present invention, with reference to a specific application scenario.

Example 1

In a distributed cooperative communication system, the number of base stations participating in current cooperation is 2, and the number of users served by a current cooperative base station set is K.

The base station 1 and the base station 2 respectively obtain the downlink channel information H of the kth user according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k

The transmission signal of the base station 1 is not phase rotated, i.e.The final precoding vector of base station 1 is

\tilde{W_{1, k}} = W_{1, k}

The base station 2 finds an optimum rotation angle θ from a pre-designed angle codebook according to the following equation so that the following equation is satisfied

And the final precoding vector calculated by the method is multiplied by the original transmitting signal to finish the distributed precoding.

Example 2

The base station 1 and the base station 2 respectively obtain a coefficient matrix H of a downlink channel of a kth user according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k

The transmission signal of the base station 1 is not phase-rotated, i.e. R₁The final precoding vector of base station 1 is 1

\tilde{W_{1, k}} = W_{1, k}

Example 3

Assume that the base stations participating in the cooperation are base station 1, base station 2, and base station 3, and the number of service users in the three cooperation base stations is K.

The base station 1, the base station 2 and the base station 3 respectively obtain a coefficient matrix H of a downlink channel of a kth user according to measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k。

The base station 2 and the base station 3 seek an optimum rotation angle theta from a pre-designed codebook according to the following formula₂And theta₃So that the following equation holds

Example 4

The phase rotation factor of the base station 2 is calculated using the following formula

In the formula, H_1,kAnd H_2,kThe downlink channel coefficient matrices of base station 1 and base station 2 to user k are respectively represented.

According to the obtained phase rotation factor of the base station 2The phase rotation factor of the base station 3 is calculated using the following formula

In the formula, H_1,k、H_2,kAnd H_3,kThe downlink channel coefficient matrices of base station 1, base station 2 and base station 3 to user k are respectively represented.

It is specifically noted that the method is known or familiar to those skilled in the art without inventive step, except for the parts described in detail in the examples.

The invention also provides a transmitted signal preprocessing and transmitting device, which is suitable for a wireless communication system comprising a first transmitting terminal and a second transmitting terminal which participate in cooperation, and comprises the following components:

a precoding vector calculation module for obtaining the k-th user downlink channel coefficient matrix H according to measurement or feedback_1,kAnd H_2,kCalculating optimal precoding vectors W each independent for the k-th user_1,kAnd W_2,k；

A final pre-coding vector calculation module for calculating the phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₂Calculating the final precoding vector of the second transmitting end

A data transmission module for transmitting the final precoding vectorAndas processing right of transmitting sideThe value processing transmitting signals are multiplied by respective original transmitting signals and are sent out through an antenna as final transmitting signals.

In addition, the present invention also provides another transmission signal preprocessing and transmitting apparatus, which is suitable for a wireless communication system including a first transmitting terminal, a second transmitting terminal, and a third transmitting terminal participating in cooperation, and includes:

The transmitting end in the invention can be a base station, a relay station, a radio remote device, a pico-base station and other control devices in a downlink in a wireless communication system. Similarly, the user is for receiving the data signal from the transmitting end, and the user may be a terminal device in an uplink in the wireless communication system, such as a mobile phone, a notebook computer, a handheld computer, and the like. The method and the device in the invention can be applied to wireless communication systems such as LTE, WIMAX and the like.

The foregoing description shows and describes one or more preferred embodiments of the present invention, but as aforementioned, it is to be understood that the invention is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A transmission signal preprocessing and transmitting method is suitable for a wireless communication system comprising a first transmitting end and a second transmitting end which participate in cooperation, and is characterized by comprising the following steps:

The transmitted signal of the first transmitting end is not subjected to phase rotation, i.e. phase rotationRotation matrix R₁1, the final precoding vector of the first transmitting end is

Calculating a phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₂Calculating the final precoding vector of the second transmitting endWherein,is a phase rotation factor, wherein a phase rotation matrix R of the second transmitting end is calculated₂The method specifically comprises the following steps: by using

Calculating of second sender

2. The method for preprocessing and transmitting signals according to claim 1, wherein the phase rotation matrix R of the second transmitting end is calculated₂And replacing with:

quantising the twiddle factor e using n bits of information^jθAngle theta in (1), i.e. constructing a set of codewords that quantize thetaContains 2 in totalⁿA m code word ofBeta is an arbitrary constant, from the setSelecting a code word theta_mCalculating θ such that the following formula takes the maximum value

Then will beAs a phase rotation matrix R for the second transmit end₂。

3. The method according to claim 1, wherein the first and second transmitters comprise a base station, a relay station, and a pico base station.

4. The method of claim 1, wherein the method is adapted to a WIMAX or LTE wireless communication system.

5. A transmitted signal preprocessing and transmitting method is suitable for a wireless communication system comprising a first transmitting end, a second transmitting end and a third transmitting end which participate in cooperation, and is characterized by comprising the following steps:

Calculating phase rotation matrix R of the second transmitting end and the third transmitting end₂、R₃According to the phase rotation matrix R of the second transmitting end and the third transmitting end respectively₂、R₃Calculating the final pre-coding vectors of the second and third transmitting ends Wherein, theIs a phase rotation factor of the second transmitting end, theIs the phase rotation factor of the third transmitting end, wherein

Calculating of second sender

6. The method for preprocessing and transmitting the transmission signal according to claim 5, wherein the phase rotation matrices R of the second and third transmitting ends are calculated₂、R₃The method specifically comprises the following steps:

according to the calculated phase rotation matrix of the second transmitting endCalculating a phase rotation matrix of the third transmitting end by adopting the following formula

Wherein, the phase rotation matrix R of the second transmitting end₂Namely, it is

Phase rotation matrix R of third transmitting end₃Namely, it is

7. The method for preprocessing and transmitting the transmission signal according to claim 6, wherein the phase rotation matrices R of the second and third transmitting ends are calculated₂、R₃Replacing the steps as follows:

quantizing a rotation matrix e using n-bit information^jθAngle in (e), i.e. constructing a set of codewords that quantize (e)Combination of Chinese herbsContains 2 in totalⁿA m code word ofBeta is an arbitrary constant, from the setSelecting two codewords theta₂And theta₃Find θ which maximizes the following equation₂And theta₃

Phase rotation matrix R of second transmitting end₂Namely, it is

Phase rotation matrix R of third transmitting end₃Namely, it is

8. The method according to claim 5, wherein the first and second transmitters comprise a base station, a relay station, and a pico base station.

9. The method of claim 5, wherein the method is adapted to WIMAX or LTE wireless communication systems.

10. A transmission signal preprocessing and transmitting apparatus, which is applied to a wireless communication system including a first transmitting end and a second transmitting end that participate in cooperation, the apparatus comprising:

{\tilde{W}}_{1, k} = W_{1, k} .

A final pre-coding vector calculation module for calculating the phase rotation matrix R of the second transmitting end₂According to the phase rotation matrix R of the second transmitting end₂Calculating the final precoding vector of the second transmitting endWherein a phase rotation matrix R of the second transmitting end is calculated₂Namely, it isThe method specifically comprises the following steps: by using

Calculating of second sender

11. A transmission signal preprocessing and transmitting device is suitable for a wireless communication system comprising a first transmitting terminal, a second transmitting terminal and a third transmitting terminal which participate in cooperation, and is characterized by comprising:

precoding vector calculation moduleA block for obtaining the k-th user downlink channel coefficient matrix H according to the measurement or feedback_1,k、H_2,kAnd H_3,kCalculating optimal precoding vectors W each independent for the k-th user_1,k、W_2,kAnd W_3,k；

{\tilde{W}}_{1, k} = W_{1, k};

A final pre-coding vector calculation module for calculating phase rotation matrix R of the second and third transmitting ends₂、R₃According to the phase rotation matrix R of the second transmitting end and the third transmitting end respectively₂、R₃Calculating the final pre-coding vectors of the second and third transmitting endsWherein a phase rotation matrix R of the second transmitting end is calculated₂The method specifically comprises the following steps: wherein, adoptCalculating of second senderWherein, the phase rotation matrix R of the second transmitting end₂Namely, it isPhase rotation matrix R of third transmitting end₃Namely, it is