WO2012129937A1

WO2012129937A1 - Distributed preprocessing method and system for multi-base station multi-user downlink transmission

Info

Publication number: WO2012129937A1
Application number: PCT/CN2011/084208
Authority: WO
Inventors: 焦晓晓; 朱登魁
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-03-28
Filing date: 2011-12-19
Publication date: 2012-10-04
Also published as: CN102710388B; CN102710388A

Abstract

Disclosed is a distributed preprocessing method for multi-base station multi-user downlink transmission, comprising: each control station participating in the coordination transmits a measurement signal to K number of terminals, where K is equal to or greater than 1; each terminal receives the measurement signal from the control station, generates measurement signal feedback information, and sends the feedback information to each control station participating in the coordination respectively; each control station participating in the coordination receives the measurement signal feedback information from the terminal, calculates a precoding matrix and generates precoding information and sends the precoding information to each terminal; each terminal receives the precoding information from each control station, adjusts the precoding information, and feeds the adjusted precoding information back to each control station; each control station determines the precoding matrix again according to the adjusted precoding information fed back by the terminal, and the downlink signals after being processed by the precoding matrix are sent to the terminal, thereby implementing user data transmission from the downlink base station to the terminal. The present invention improves the performance of the entire network.

Description

Distributed preprocessing method and system for multi-base station multi-user downlink transmission

The present invention belongs to the field of wireless communication technologies, and in particular, to a distributed preprocessing method and system for multi-base station multi-user downlink transmission. Background technique

Multiple Input Multiple Output (MIMO), which uses multiple antennas at both ends to improve system performance, has been widely used in various 3G/B3G/4G systems. In the field of MIMO technology applications, there are single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO). The SU-MIMO corresponds to a time-frequency resource of the base station and the user terminal, and the base station communicates with a single user terminal on a specific time-frequency resource through multiple antennas. In MU-MIMO, as the number of users increases, the base station simultaneously communicates with multiple different user terminals on the same time-frequency resource through multiple antennas, which can simultaneously improve the communication capability between the base station and multiple users. However, regardless of whether SU-MIMO or MU-MIMO described above, most of the research is limited to the case where the base station uses only its own antenna to communicate with a single or multiple users. In many wireless communication networks, if the MIMO communication of the user can be reasonably considered by the base station of the current cell and other base stations with good communication quality, the communication capability of the user must be improved compared to the single base station service, This multi-base station distributed MU-MIMO has received widespread attention at present. Specifically, the multi-base station distributed MU-MIMO uses multiple neighboring base stations to communicate with multiple user terminals on the same time-frequency resource.

In general, MIMO precoding is required before the data is transmitted from the antenna. The precoding technique is designed to preprocess the transmitted signal by using Channel-Aide Information at the Transmitter (CSIT). The signal beam points to the "direction" that is most beneficial to the user's reception, thereby achieving interference suppression to improve the user's received signal-to-noise ratio. For closed loop space complex With transmission, the technique of selecting a precoding matrix based on a codebook is based on a PMI (Precoding Matrix Indicator).

In the current cellular wireless communication network, when multiple base stations serve the same user, it is necessary to comprehensively consider the channel of each base station to the user, and select the most suitable precoding matrix. The existing Coordinated Multipoint Transmission/Reception (CoMP) technology is implemented by exchanging information between base stations. However, for multi-base station distributed MU-MIMO, each participating base station needs to acquire channel information between each user and all base stations, and the information transmission amount thereof is very large, and the interface between the uplink channel and the base station is one. A huge challenge, especially considering the fact that the base station is far away, it is difficult to achieve information interaction between these base stations. Therefore, in order to improve the performance of cell edge users, achieve interference avoidance and maximize transmission, distributed preprocessing technology that does not rely on information exchange between base stations and can implement interference suppression has become a very urgent problem. Summary of the invention

To solve the above technical problem, an aspect of the present invention provides a distributed preprocessing method for multi-base station multi-user downlink transmission, including:

Each participating control station sends measurement signals to K terminals, K is greater than or equal to 1; each terminal receives measurement signal generation measurement signal feedback information from the control station and sends it to each participating control station;

Each participating control station receives measurement signal feedback information from the terminal, calculates a precoding matrix, and generates precoding information to be transmitted to each terminal;

Each terminal receives precoding information from each control station, and adjusts the precoding information, and feeds the adjusted precoding information to each control station;

Each control station determines the precoding matrix again according to the adjusted precoding information fed back by the terminal, and the downlink signal is processed by the precoding matrix and then sent to the terminal to implement downlink data transmission from the base station to the terminal. Another aspect of the present invention provides a distributed pre-processing system for multi-base station multi-user downlink transmission, including a plurality of control stations and K terminals participating in the cooperation, where K is greater than or equal to 1, and further includes:

a measurement signal sending module, configured to implement each of the participating control stations to send measurement signals to K terminals, where K is greater than or equal to 1;

a measurement signal feedback information generating and transmitting module, configured to receive a measurement signal from the control station, generate measurement signal feedback information, and separately send to each control station participating in the cooperation;

a precoding matrix calculation and precoding information generating module, configured to receive measurement signal feedback information from the terminal, calculate a precoding matrix, and generate precoding information to be sent to each terminal;

a precoding information adjustment and feedback module, configured to receive precoding information from each control station, and adjust precoding information, and feed the adjusted precoding information to each control station;

The precoding matrix determining module is configured to determine the precoding matrix again, so that the downlink signal is processed by the precoding matrix and then sent to the terminal to implement downlink base station to terminal user data transmission.

Through the above technical solution, the present invention adopts the distributed precoding technology, does not require information exchange between base stations, improves the gain of the user of the cell, and suppresses interference to neighboring cell users, and expands the distribution of multiple base stations to a certain extent. The communication capabilities of users in MU-MIMO improve the performance of the entire network. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

1 is a schematic diagram of an application scenario of a wireless communication network according to an embodiment of the present invention;

2 is a flowchart of a technical solution according to an embodiment of the present invention;

3 is a flow chart of a preferred embodiment of the present invention when it relates to a data stream;

4 is a flow chart of another preferred embodiment of the present invention relating to multiple data streams. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic idea of the present invention is: Each control station participating in cooperation sends a measurement signal to K terminals, K is greater than or equal to 1; each terminal receives measurement signal from the control station to generate measurement signal feedback information is sent to each a control station participating in the cooperation; each participating control station receives measurement signal feedback information from the terminal, calculates a precoding matrix and generates precoding information to be transmitted to each terminal; each terminal receives precoding information from each control station, And precoding the precoding information, and feeding back the adjusted precoding information to each control station; each control station determines the precoding matrix again according to the adjusted precoding information fed back by the terminal, and the downlink signal passes through the precoding matrix. After processing, it is sent to the terminal to implement user data transmission from the downlink base station to the terminal.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments in order to make the present invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

FIG. 1 is a schematic diagram of a wireless communication network application scenario using a multi-base station distributed MU-MIMO precoding technique according to an embodiment of the present invention.

For MU-MIMO multiple base station transmission, where the base station is the control station, considering N(N > 1) base stations, and transmitting data for Κ(Κ≥\) users, here for the user /^ = 1, · · ·, , the technical solution of the present invention is described in detail:

Step 1: The base station sends a measurement signal to the user terminal.

Specifically, each base station separately sends a measurement signal to the user terminals, where the measurement signal includes auxiliary information for determining channel related information of the base station to the user terminal, and the auxiliary information of the channel related information may be according to the measurement signal. Reference information (such as RS, reference signal) or pilot, etc., channel coefficient matrix H obtained by channel estimation.

Step 2: The user terminal receives the measurement signal from the base station, and generates measurement signal feedback information, which are respectively sent to each base station; Specifically, the first user terminal receives measurement signals from all base stations to the user terminal, and determines, according to the auxiliary determination information (which may be reference information, such as RS) in the measurement signal, each base station to the first user respectively. Downlink channel information of the terminal, the downlink channel information mainly refers to a channel coefficient matrix H of the control station to the terminal; wherein = 1, ... indicates one of the user terminals

The user terminal generates corresponding measurement signal feedback information according to the downlink channel information according to the downlink channel information of each base station to the user terminal, and feeds back to each base station. The measurement signal feedback information mainly refers to PMI (Precoding Matrix Indication/Index) information or PMI (Preferred Matrix Indication/Index) that is most closely matched to the channel information reported by the user terminal. , referred to as PMI information.

Step 3: Each base station receives feedback information from the user terminal, initially determines a precoding matrix, and generates precoding information to send to the user terminal.

Specifically, each base station receives feedback information from each user terminal, and each base station uses the PMI information fed back by the paired MU-MIMO user to calculate a precoding matrix corresponding to each user, and obtain corresponding precoding information, and The information is notified to each user terminal, and the precoding information generally refers to precoding matrix indication (PMI) information corresponding to the precoding matrix.

The paired MU-MIMO user refers to a user scheduled on the same time-frequency resource, and the base station coordinates the downlink precoding matrix of the user terminal by pairing the PMI fed back by the MU-MIMO user to achieve suppression of co-channel interference.

The base station may notify the user terminal of the precoding information by using a downlink control channel or a broadcast channel or a data traffic channel;

The precoding information may be a precoding matrix obtained by the base station after the calculation; wherein the precoding information may be when the precoding matrix is quantized into a codeword in a system preset codeword set, the codeword The corresponding index value. Step 4: Each user terminal receives precoding information from each base station, and adjusts the precoding information, and then re-feeds the adjusted precoding information to each base station;

Specifically, the user terminal receives downlink precoding information of each user to the user, and the N base stations in the communication network transmit the same signal. After different precoding and channel functions, the data received by the user may be expressed as:

N N K

=∑H _k w _k s _k +∑∑H, _k W. _jSj +n _k

i=\ i=\ j=\

J≠k where H denotes the channel coefficient matrix between the first base station and the first user, indicating the precoding matrix between the i-th base station and the first user, Wi, _k GG ( ^Λ ^ is the number of transmitting antennas, L is The number of data streams), ∑H. _k W, _k s _k represents the expected signal of user k, |;|;1^ , ^ denotes multiuser i=li=lj=l

J≠k

Interference between, indicating channel noise.

When the base station accurately obtains the channel coefficient H _ik , in order to avoid the multi-base station to the user terminal signals cancel each other, thereby obtaining the combining gain brought by the multiple base stations, the coherence combining needs to be achieved, that is, the H ^ i ^ Each column vector of the precoding matrix ^ is phase adjusted. According to the number of data streams transmitted by the base station to the user, there are two adjustment schemes: Solution Α: When the number of data streams is 1, the precoding matrix is a matrix of Mxl, that is, a precoding vector, and only these pre-codings are needed. The coding vectors are phase-adjusted such that the respective phases are equalized to each of H _i ^, and the phase-adjusted pre-coding vector is quantized, represented by a pre-coding vector _Λ in the codebook, where = W _ik e ^je '. Scheme B: When the number of data streams is >1, the precoding matrix is a matrix of Mx, and each phase corresponding to the precoding matrix (the column vector of the precoding matrix) needs to be phase-adjusted, and the obtained new H^U is made. The corresponding data stream has the same phase, where ί/^( ,..., is the moment The array includes phase adjustment information for each stream, and quantizes the phase adjusted precoding matrix, represented by a precoding matrix in the codebook, where ': = w. _k u. _k . The number of data streams L is related to the rank of the channel: the channel coefficient C, the rank of the channel rank(H) ≤ ^min ^'^), where ^ is the number of transmitting antennas, and ^ is the number of receiving antennas. Under space division multiplexing, L = rank ( H ).

The user terminal feeds back the adjusted information to each base station according to the new precoding matrix. There are two alternative precoding adjustment methods: Method a: Select any one of the base stations to the user terminal i / _it = / / / / is the unit matrix, that is, the phase of ^^ Benchmark, adjust the ^^ phase of other base stations to the user, so that all H _ik W _iJC目^;歹目^ i;

Mode b: Neither takes the unit matrix I, that is, does not reference the phase of each column vector of any H i^, but gives a reference phase for the corresponding column vector of each matrix, that is, all Ψ _ί needs to be adjusted. Finally, all Η _ί Ψ _ί歹'J are the same. There are two options for adjusting the base station based on user feedback:

Manner 1: The user terminal feeds back the adjustment angle of each column of each precoding matrix to each corresponding base station;

Method 2: Generate PMI information according to the adjusted precoding matrices, and feed back the PMI information to the corresponding base stations.

Step 5: Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication. The specific embodiment is further used in the following. The method of the invention is illustrated.

The following embodiments 1-2 are used to illustrate the case where two base stations have two users, wherein the downlink data stream is one distributed precoding. As shown in FIG. 1, there are two base stations BS1 and BS2 in the network structure, and two user terminals MS1 and MS2. Taking the user terminal MS1 as an example, the two base stations BS1 and BS2 are jointly served for two users MS1 and MS2, and the process of downlink communication is implemented by distributed precoding.

First, the base station BS1 and the base station BS2 send measurement signals to the user MS1 and the user MS2. Then, the MS1 determines the downlink channel information H _{u of the} BS1 to the MS1 by receiving the measurement signal of the BS1, and calculates the downlink of the BS1 to the MS1 according to the channel information. a precoding vector ^ of the path, and then generating precoding information PM/u according to the precoding vector to the base station BS1;

The MS1 determines the downlink channel information H _{21 of the} BS2 to the MS1 through the received measurement signal of the BS2, and calculates a precoding vector _{21 of the} BS2 to the MSI downlink according to the channel information, and generates precoding information PM according to the precoding vector. / ₂₁ feedback to the base station BS2;

Through the same process as the above MS1, the user terminal MS2 feeds back the precoding information PM/ ₁₂ to the base station BS1, and the user terminal MS2 feeds back the precoding information PM/ ₂₂ to the base station BS2.

Then, the base station BS1 feeds back the PM/u of the BS1 and the user MS2 fed back to the PM/ _{12 of the} BS1, coordinates the PMI to suppress the co-channel interference, and determines their optimal precoding vectors, respectively, and obtains the coordinated The new PM/u is sent to MS1 and the new PM/ _{12 is} sent to MS2. Similarly BS2 sends the corresponding coordinated PMI to MS1 and MS2.

Embodiment 1: It is used to describe the case where two base stations and two users downlink transmit one data stream, and the distributed precoding of mode a and mode 1 is adopted.

Please refer to Figure 1 and Figure 3. In this embodiment, a two-base station is used as an example to transmit a data stream, which illustrates the process of implementing downlink data transmission by using mode 1 and mode a distributed precoding.

The user terminal MS1 receives the precoding information from the base stations BS1, BS2, and the corresponding new precoding vector is ^ and the precoding vector of BS2 to MS1 is W ₂₁ .

In order to achieve coherent combining of the signals of the one stream in the user terminal MS1, the precoding vector can be adjusted by the method a, that is, „unchanged, ₂ ; = w ₂₁ e. Meets H _{21 21} e ^M and ^ See the same purpose.

After the adjustment of the user terminal is completed, the information needs to be fed back to the base station again. The feedback content can adopt mode 1, that is, the user terminal only needs to feed back the adjustment angle of the base station BS2 to the base station BS2. BS2 adjusts the information according to the received angle to obtain the final precoding vector of the downlink transmission ^ ' = ^ ₂₁ ^ , and the precoding matrix of BS1 is not adjusted.

Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication.

Embodiment 2: It is used to describe the case where two base stations and two users downlink transmit one data stream, and the distributed precoding of mode b and mode 2 is adopted.

Referring to FIG. 1 and FIG. 3, in this embodiment, a data flow is transmitted by using two users of the two base stations as an example to illustrate the process of implementing downlink data transmission by adopting mode 2 and mode b distributed precoding.

In order to implement coherent combining on the signal of the one stream in the user terminal MS1, the precoding vector can be adjusted by using mode b, that is,

θ _λ , satisfy: H _u u' and H _{21 21} ' ~ ^; Standing.

After the adjustment of the user terminal is completed, the information needs to be fed back to the base station again. The feedback content may adopt mode 2, that is, the user terminal generates new PMI information according to ^ ', and feeds back to the base station BS1, and the BS1 determines that the precoding vector is ^ ' according to the PMI information fed back by the new MS1; the user terminal generates a new PMI according to ^ ' The information is fed back to the base station BS2. BS2 determines that the precoding vector is ₂₁ ' according to the PMI information fed back by the new MS1. Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication.

The following embodiments 3-4 are used to describe three base stations and three users, where the downlink data stream is one. The case of cloth precoding.

As shown in Fig. 1, there are three base stations BS1, BS2 and BS3 and three user terminals MS1, MS2 and MS3 in the network structure. Taking the user terminal MSI as an example, it describes that BS1, BS2, and BS3 jointly serve MSI, MS2, and MS3, and implements downlink communication through distributed precoding.

First, the base stations BS1, BS2, and BS3 transmit measurement signals to the user MS1, the user MS2, and the user MS3.

Next, the MS1 determines the downlink channel information H _{u of the} BS1 to the MS1 by receiving the measurement signal of the BS1, and calculates a precoding vector of the downlink of the BS1 to the MS1 according to the channel information, and generates precoding information according to the precoding vector. PM/u feedback to the base station BS1;

Likewise, MS1 received by BS2, BS3, BS2 to MS1 determines the downlink channel information of the channel H _21, downlink channel information MSI to BS3 H _31. The BS2 to MS1 downlink precoding vector _{21 is} then calculated based on the channel information, and then the BS3 to MS1 downlink precoding vector is calculated based on the channel information. Then, according to the precoding vector, the precoding information W/ _{21 is} fed back to the base station BS2, and _{31 is} fed back to the base station BS3;

After the same process as the above MS1, the user terminal MS2 feeds back the precoding information PM/ ₁₂ to the base station BS1, the feedback precoding information PM/ ₂₂ to the base station BS2, and the feedback precoding information PM/ ₃₂ to the base station BS3; the user terminal MS3 feeds back the precoding information. The PMI is to the base station BS1, the user terminal MS3 feeds back the precoding information PM/ ₂₃ to the base station BS3, and the user terminal MS3 feeds back the precoding information PM/ ₃₃ to the base station BS3.

Then, the base station BS1 feeds back to the PMI _U and the user MS2 fed back to the BS1 according to the user MS1.

The PMI _{l2 of the} BS1 and the user MS3 feed back to the ΡΜΙ of the BS1, coordinate the PMI to suppress the co-channel interference, and determine their optimal precoding vectors respectively, and send the coordinated new ΡΜ/„ to the MS1 and the new PMI _l2 to MS2, new ΡΜΙ is sent to MS3. Similarly BS2, BS3 send the corresponding ΡΜΙ to MS1 and MS2, MS3. Embodiment 3: It is used to describe the case where the three base station three-user downlink transmission data stream is a distributed pre-coding method using mode b and mode 1.

Please refer to Figure 1 and Figure 3. In this embodiment, a three-base station and three users are taken as an example to transmit a data stream, which illustrates a process of implementing downlink data transmission by using mode b and mode 1 distributed precoding.

The user terminal MS1 receives the precoding information from the base stations BS1, BS2 and BS3, and the corresponding new precoding vectors are i, W _2L and ₃₁ , respectively. In order to achieve coherent combining at the user terminal MSI, the precoding vector can be adjusted in the manner b, ie W _N = W _n e ^jf)l , ₂₁ ' = W _2l e ^{jf) 2} , W = W _3l e ^M . And ^ 5 satisfy: H _N W _N , H _2L W _2l e ^M and H ₃ , ₃₁ ' have the same phase. After the adjustment of the user terminal is completed, it needs to be fed back to the base station again. Mode 1 can be adopted, that is, the user terminal feeds back the adjustment angle of the base station BS2 to the base station BS2 and the adjustment angle of the base station BS3 to the base station BS3. The precoding matrix of BS1 is unchanged, and BS2 and BS3 adjust the information according to the received angle to obtain the final precoding vector ₂₁ ' = ₂₁ ' and w _{3 of the} downlink transmission;

Embodiment 4: It is used to describe the case where the three base station three-user downlink transmission data stream is a distributed pre-coding method using modes a and 2.

Referring to FIG. 1 and FIG. 3, in this embodiment, a three-base station and three users are taken as an example to transmit a data flow, which illustrates a process of implementing downlink data transmission by using mode 2 and mode a distributed pre-coding.

The user terminal MS1 receives the precoding information from the base stations BS1, BS2 and BS3, and the corresponding new precoding vectors are i, W _2L and ₃₁ , respectively. In order to achieve coherent combining at the user terminal MSI, the precoding vector can be adjusted using mode a, ie „unchanged, ₂₁ ' = ₂₁ e , ₃₁ ' = w _3l e ^M ₀ , and satisfies: H _U W _U . H _2l w _n and H ₃ , ₃₁ ' have the same phase. After the adjustment of the user terminal is completed, it needs to be fed back to the base station again. Mode 2, that is, the user terminal generates new PMI information according to ^ ', and feeds back to the base station BS1, and the BS1 determines that the precoding vector is ^ ' according to the PMI information fed back by the new MS1; the user terminal generates a new one according to ₂₁ ', ^' The PMI information is fed back to the base stations BS2, BS3, respectively. BS2 and BS3 respectively determine that the precoding vector is ₂₁ ', ₃₁ ' according to the new PMI information fed back by the MSI. Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication.

The following embodiments 5-6 are used to illustrate the case where two base stations are two users, where the downlink data stream is two distributed precoding.

As shown in Figure 1, there are three base stations BS1, BS2 and BS3 in the network structure, and two user terminals MS1.

MS2. Taking the user terminal MSI as an example, it describes that BS1, BS2, and BS3 jointly serve MS1, MS2, and MS3, and implements downlink communication through distributed precoding.

First, the base stations BS1, BS2 and BS3 transmit measurement signals to the users MS1, MS2 and MS3. Next, the MS1 determines the downlink channel information Hu of the BS1 to the MS1 by receiving the measurement signal of the BS1, and calculates a precoding matrix of the downlink of the BS1 to the MS1 according to the channel information, and generates precoding information PM according to the precoding matrix. /u feedback to the base station BS1;

Similarly, the MS1 determines the downlink channel information H ₂₁ , BS3 of the BS2 to the MSI, and the downlink channel information H _{31 of the} MSI through the received BS2 and BS3. The BS2 to MS1 downlink precoding matrix _{21 is} then calculated based on the channel information, and then the BS3 to MS1 downlink precoding matrix _{31 is} calculated based on the channel information. Generating precoding information W/ ₂₁ according to the precoding matrix and feeding back to the base station

BS2, _{31 is} fed back to the base station BS3; after the same process as the above MS1, the user terminal MS2 feeds back the precoding information PM/ ₁₂ to the base station BS1, the feedback precoding information PM/ ₂₂ to the base station BS2, and the feedback precoding information PM/ ₃₂ to the base station. BS3. Then, the base station BS1 feeds back to the PMI _{U of the} BS1 and the user MS2 fed back to the PM/ _{12 of the} BS1 according to the user MSI, coordinates the PMI to suppress the co-channel interference, thereby respectively determining their optimal precoding matrix, and will obtain new cooperation through coordination. The PMIu is sent to the MS 1, and the new PMI _{U is} sent to the MS2. Similarly, BS2 and BS3 send corresponding new PMIs to MS1 and MS2.

Embodiment 5: It is used to describe the case where two users of three base stations transmit two data streams in the downlink, and adopt the distributed precoding of mode a and mode 1.

Please refer to Figure 1 and Figure 4. In this embodiment, the two users of the three base stations are taken as an example to describe the process of transmitting the downlink data transmission by using the distributed precoding of the two data streams by using mode b and mode 1.

The user terminal MS1 receives the precoding information from the base stations BS1, BS2 and BS3, and since the data of the two streams is transmitted, the precoding matrix is not a vector. The corresponding new precoding matrices are u, ₂₁ and _{31 respectively} . In order to implement coherent combining of multiple streams in the user terminal MSI, the precoding matrix can be adjusted by mode a, that is, ^^ where f/ _u = /, ie, 0, ₂ =0. So ^':^ is not changed, w ₂ ; = w _2l u _2l , w ₃ ; = w _3l u _{3l 0} where υ _η (θ _η , ₂ ), U _2l ( θ ₂₁ , θ ₂₂ )^υ ₃₁ ( θ ₃₁ , θ ₃₂ ) satisfies: H _uu , H _{2i 21} ' and H _{3i 31} ' of the two data streams have the same phase. After the adjustment of the user terminal is completed, it needs to be fed back to the base station again. Mode 1, that is, the user terminal adjusts the angle of the corresponding data stream of the base station BS2, quantizes the feedback to the base station BS2, adjusts the corresponding data stream of the base station BS3, and quantizes the signal to the base station BS3. The precoding matrix of BS1 is unchanged, and BS2 and BS3 calculate the final precoding matrix ₂₁ ' = w _2l u _2l , ₃₁ ' = w _3l u _{3l of the} downlink transmission according to the received angle adjustment information. Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication.

Embodiment 6: It is used to describe two users of three base stations, two data streams are downlinked, and the distributed precoding of mode b and mode 2 is adopted. Please refer to Figure 1 and Figure 4. In this embodiment, the two users of the three base stations are taken as an example to describe the process of transmitting the downlink data transmission by using the distributed precoding of the two data streams by using mode a and mode 2.

The user terminal MS1 receives the precoding information from the base stations BS1, BS2 and BS3, and since the data of the two streams is transmitted, the precoding matrix is not a vector. The corresponding new precoding matrices are u, ₂₁ and _{31 respectively} . In order to implement multi-stream coherent combining in the user terminal MSI, the precoding matrix can be adjusted by using mode b, that is,

, w ₂ ;=w _2l u _2l , w ₃ ; = w _3l u _{3l 0} υ _η (θ _η , θ _η ) . u _2l ( θ ₂₁ , θ ₂₂ ) υ ₃₁ ( θ ₃₁ , Θ ₃₂ ) υ ₃ ( Θ ₃₁ , ₂ ) Satisfaction: H _uu , H _{21 21} ' and H _{31 31} '~ ^ of two data streams; Standing. After the adjustment of the user terminal is completed, it needs to be fed back to the base station again. Mode 1, that is, the user terminal adjusts the angle of the corresponding data stream of the base station BS2, quantizes the feedback to the base station BS2, adjusts the corresponding data stream of the base station BS3, and quantizes the signal to the base station BS3. BS2 and BS3 calculate the final precoding matrix of the downlink transmission according to the received angle adjustment information.

W ^γγ 21 -W "21

°

After the adjustment of the user terminal is completed, it needs to be fed back to the base station again. Mode 2, that is, the user terminal generates new ΡΜΙ information according to ^ ', and feeds back to the base station BS1, and the BS1 calculates the precoding matrix according to the ΡΜΙ information fed back by the new MS1; the user terminal generates a new according to ₂₁ ', ff ₃₁ ' The PMI information is fed back to the base stations BS2, BS3, respectively. BS2 and BS3 respectively calculate the corresponding precoding matrix according to the PMI information fed back by the MSI, that is, ₂₁ ', W _3l '. Each base station determines a precoding matrix according to the adjusted precoding information fed back by the user, and the downlink signal is processed by the precoding matrix and then sent to the user terminal to implement downlink data communication.

In addition, the distributed pre-processing system for multi-base station multi-user downlink transmission of the present invention includes a plurality of control stations and K terminals participating in cooperation, wherein K is greater than or equal to 1, and further includes: a measurement signal sending module, configured to implement each Control stations participating in the collaboration send measurement signals to K terminals, Κ greater than or equal to 1;

The above description shows and describes one or more preferred embodiments of the present invention, but as described above, it should be understood that the invention is not limited to the form disclosed herein, and It can be used in a variety of other combinations, modifications, and environments, and can be modified by the teachings or related art or knowledge within the scope of the inventive concept described herein. All changes and modifications made by those skilled in the art are intended to be within the scope of the appended claims.

Claims

Claim

A distributed preprocessing method for multi-base station multi-user downlink transmission, which is characterized in that:

Each control station determines the precoding matrix again according to the adjusted precoding information fed back by the terminal, and the downlink signal is processed by the precoding matrix and then sent to the terminal to implement downlink data transmission from the base station to the terminal.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 1, wherein the measurement signal comprises auxiliary information for determining channel related information of the control station to the terminal.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 2, wherein each of the terminals receives measurement signal generation measurement signal feedback information from the control station and sends each feedback cooperation The control station includes: each terminal receives measurement signals from all control stations, and determines, according to the auxiliary determination information in the measurement signal, each of the participating control stations to respective downlink channel information, and then according to the downlink channel information. The measurement signal feedback information is generated and sent to each of the participating control stations.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 1 or 3, wherein the measurement signal feedback information is a precoding matrix indication that is correctly matched by the terminal and matched with the downlink channel information. Information or optimal matrix indication information.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 4, wherein each of the participating control stations receives measurement signal feedback information from the terminal, calculates a precoding matrix and generates Sending the precoding information to each terminal includes: each control station participating in the cooperation receives the measurement signal feedback information from each terminal, and uses the precoding matrix indication information or the optimal matrix indication information fed back by the paired MU-MIMO user. The precoding matrix corresponding to each terminal is generated to generate precoding information and sent to each terminal.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 5, wherein the paired MU-MIMO user is a terminal scheduled on the same time-frequency resource.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 5, wherein the pre-coding information is sent by a control station participating in cooperation to a downlink control channel, a broadcast channel, or a data traffic channel. Each terminal.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 5, wherein the precoding information is when the precoding matrix is quantized into a codeword in a system pre-defined codeword set. , the index value corresponding to the codeword.

The distributed pre-processing method for multi-base station multi-user downlink transmission according to claim 1 or 3, wherein the control station is a base station or a relay station.

A distributed pre-processing system for multi-base station multi-user downlink transmission, comprising a plurality of control stations and K terminals participating in cooperation, wherein K is greater than or equal to 1, and further comprising: a measurement signal sending module, configured to: Implementing each participating control station to send measurement signals to K terminals, K is greater than or equal to 1;

a precoding matrix calculation and precoding information generating module, configured to receive measurement signal feedback information from the terminal, calculate a precoding matrix, and generate precoding information to be sent to each terminal; a precoding information adjustment and feedback module, configured to receive precoding information from each control station, and adjust precoding information, and feed the adjusted precoding information to each control station;

11. The distributed pre-processing system for multi-base station multi-user downlink transmission according to claim 10, wherein the control station is a base station or a relay station.