WO2009152645A1

WO2009152645A1 - Method and apparatus for collaboratively transmitting signals with other base stations in base station

Info

Publication number: WO2009152645A1
Application number: PCT/CN2008/001202
Authority: WO
Inventors: 杨红卫; 朱孝龙
Original assignee: 上海贝尔阿尔卡特股份有限公司; 阿尔卡特朗讯
Priority date: 2008-06-20
Filing date: 2008-06-20
Publication date: 2009-12-23
Also published as: CN101919182A; CN101919182B

Abstract

The solution for collaboratively transmitting signals in wireless communication network base station with one base station or multiple base stations to one mobile station or multiple mobile stations in the same time-frequency resource is provided. In the solution, the base stations use the obtained long time channel information of one mobile station or multiple mobile stations to pre-process the signals to be transmitted to one mobile station or multiple mobile stations in order to make each mobile station receive non-intrusively the transmitted signals. The collaborative system of the present invention avoids effectively interference of cells, increases coverage area of cells and throughput of system because multiple base stations serve one mobile station or multiple mobile stations in the same time-frequency resource. Mobility of the mobile station is supported commendably, measurement number of channel information is reduced greatly and the solution is realized easily because each base station uses not short time channel information but long time channel information.

Description

Used in base stations to cooperate with other base stations

Method and device for transmitting signals

The present invention relates to a base station in a wireless communication network, and more particularly to a method and apparatus for transmitting signals to one or more mobile stations in cooperation with other base stations. Background technique

With the evolution of IEEE 802.16e and 3GPP LTE to the IMT-advanced standard, IEEE 802.16m and 3GPP LTE+ are dedicated to higher sector throughput, cell edge user throughput, and wider cell coverage. In a low frequency reuse system, cell throughput and coverage are limited due to inter-cell interference (ICI). In IEEE 802.16e and 3GPP LTE, there are many methods for eliminating inter-cell interference, such as power control based on inter-cell interference, flexible frequency reuse, macro diversity, interference randomization, and the like. These methods for eliminating inter-cell interference can effectively improve the throughput of the cell edge users, but the system frequency is not efficient, and the complexity of the receiving device is increased. In addition, from the viewpoint of channel capacity, although various methods for eliminating inter-cell interference are employed, the system capacity of a communication system having inter-cell interference is still lower than that without inter-cell interference. Summary of the invention

The invention is based on a collaborative MIMO (Co-MIMO) technology for synchronous wireless communication networks proposed by the same applicant Shanghai Bell Alcatel in 2007 (see CN200710045052.0), This patent application is hereby incorporated by reference in its entirety. The so-called cooperative MIMO technology is: Through coordination between multiple base stations, multiple base stations simultaneously serve one or more mobile stations on the same time-frequency resource, and the signals to be transmitted are processed by precoding technology or beamforming to avoid Small interval interference. Thereby, the average capacity of the cell and the average throughput of the user, especially the user throughput at the edge of the cell, are improved. Based on the concept of collaborative MIMO, confirm this Patent application CN20071004 ⁵ 052.0 proposes a specific implementation scheme based on Instantaneous channel state information (ICSI, or also referred to as short-term channel information) (hereinafter referred to as "ICSI-based cooperative MIMO,"). ICSI's cooperative MIMO is a priority scheme for time-division multiplexing systems with low mobility, because in a low mobility time division multiplexing system, the channel relative change is slow, and the base station can easily obtain channel information. However, for high mobility time division In the multiplex system, the base station often cannot obtain the instant channel information in time due to the relatively fast change of the channel. For the frequency division multiplexing system, the base station often cannot obtain the instant channel information in time due to the asymmetry of the uplink and downlink channels. The estimated value of the channel information used in the calculation process of the precoding coefficient or beamforming often cannot reflect the influence of the actual channel when the signal is transmitted, thereby causing the performance of the entire system to decrease, and the error rate of the receiving device to be improved. Technology and patent application CN200710045052.0 The present invention further provides a method for cooperatively transmitting signals to one or more mobile stations on a same time-frequency resource of another one or more base stations in a base station of a wireless communication network ( For convenience, a technical solution referred to as "collaborative system" for short. In the solution of the present invention, the base station uses its acquired long-term channel information to one or more mobile stations to be sent to one or more mobiles. The signals of the station are pre-processed so that each mobile station can receive the signal transmitted thereto without interference. For the sake of clarity, the following describes various working modes of the cooperative system based on long-term channel information work in the present invention, The working modes of the collaborative system include but are not limited to the following situations:

- multiple base stations serve a mobile station by means of joint closed-loop space-time coding;

- Multiple base stations serve a mobile station in macro diversity mode

- a plurality of base stations serve a plurality of mobile stations in a cooperative MIMO manner, wherein each base station serves a plurality of mobile stations in a multi-user MIMO manner, wherein there are various rules for determining precoding coefficients of multi-user MIMO, typically The ground includes, but is not limited to, a precoding rule based on a covariance matrix of a channel response matrix, a beamforming rule based on a signal exit angle or an angle of arrival, and the like.

According to a first aspect of the present invention, there is provided a use in a base station of a wireless communication network A method for cooperatively transmitting signals to one or more mobile stations on the same time-frequency resource as the other one or more base stations, characterized in that it comprises the following steps: a. acquiring the base station to the one or more mobile stations Long-term channel information of a downlink wireless communication link; _b . pre-processing one or more signals transmitted by the base station to the one or more mobile stations based on the long-term channel information and a predetermined rule to obtain a The pre-processed signal; _c . transmitting the pre-processed signal to the one or more mobile stations on a time-frequency resource agreed with the other one or more base stations.

According to a second aspect of the present invention, there is provided a cooperative transmitting apparatus for cooperatively transmitting signals to one or more mobile stations on the same time-frequency resource as other one or more base stations, characterized in that the cooperative transmitting apparatus comprises An obtaining device, a pre-processing device, and a transmitting device; wherein the acquiring device is configured to acquire long-term channel information of a downlink wireless communication link of the base station to the one or more mobile stations; and the pre-processing device is configured to use the long-term based Channel information and predetermined rules, pre-processing one or more signals sent by the base station to the one or more mobile stations to obtain a pre-processed signal; and transmitting means for using one or more other ones The preprocessed signal is transmitted to the one or more mobile stations on a time-frequency resource agreed by the base station.

In the cooperative system of the present invention, since a plurality of base stations serve one or more mobile stations on the same time-frequency resource, inter-cell interference is effectively avoided, the coverage of the cell is increased, and the throughput of the system is increased. Since each base station adopts long-term channel information instead of short-term channel information to pre-process the transmitted signal, the mobility of the mobile station can be well supported, and the number of measurement of the channel information is greatly reduced, which is easy to implement. For the case where multiple base stations operate in cooperative MIMO, since precoding is performed independently by each base station, for one base station, it only needs to acquire long-term channel information of its own downlink wireless communication link between each mobile station station. That is, without long-term channel information of the downlink wireless communication link that does not involve other base stations to the respective mobile stations, the information interaction between the cooperative base stations is effectively reduced. DRAWINGS

A detailed description of a non-limiting embodiment, with reference to the accompanying drawings, Other features, objectives and advantages of Ming will become more apparent.

1 is a schematic diagram of a topology of a wireless communication network;

2 is a flowchart of a method for cooperatively transmitting signals to one or more mobile stations on a same time-frequency resource with other one or more base stations in a base station of a wireless communication network, in accordance with an embodiment of the present invention;

Figure 3 is a flow chart showing the sub-steps of the step S21 shown in Figure 2;

4 is a schematic diagram of pilot allocation in a base station of a wireless communication network in accordance with an embodiment of the present invention;

Figure 5 is a flow chart of the sub-steps of step S31 shown in Figure 3;

6 is a flow chart showing the sub-steps of step S22 in the method flow chart shown in FIG. 2. FIG. 7 is a schematic diagram showing signal processing in the network topology shown in FIG. 1 according to an embodiment of the present invention;

Figure 8 is a schematic diagram showing the signal arrival angle;

9 is a cooperative transmission device 90 for cooperatively transmitting signals to one or more mobile stations on the same time-frequency resource as other one or more base stations in a base station of a wireless communication network, in accordance with an embodiment of the present invention. Schematic block diagram of the structure;

Figure 10 is a schematic block diagram showing the structure of the obtaining device 91 of Figure 9;

11 is a schematic block diagram showing the structure of the channel response obtaining means 911 of FIG. 10; FIG. 12 is a schematic block diagram showing the structure of the preprocessing apparatus 92 of FIG.

Wherein the same or similar reference numerals denote the same or similar step features or devices (modules). detailed description

2 illustrates a flow chart of a method for cooperatively transmitting signals to one or more mobile stations on the same time-frequency resource with other one or more base stations in a base station of a wireless communication network in accordance with an embodiment of the present invention. . Those of ordinary skill in the art will appreciate that the wireless communication networks described herein include, but are not limited to, WiMAX networks, 3G networks, or next generation wireless mobile communication networks.

Those skilled in the art should understand that the two base stations B1 and B2 shown in FIG. 1 respectively Located in an adjacent cell or sector. It should be noted that, at the edge of a cell, sometimes more than two base stations can communicate with mobile stations located at the cell edge, for example, for a widely used hexagonal cell coverage model, as shown in FIG. At the mobile station at the cell junction, it is possible for three base stations to communicate with the mobile station. Specifically, for a certain mobile station, selecting a plurality of base stations and selecting which base stations to communicate with the mobile station are described in detail in the patent application CN200710045052.0, and the present invention is not described herein again.

For example, the case where the two base stations B1 and B2 shown in FIG. 1 serve two mobile stations M1 and M2 on the same time-frequency resource is used as an example, and is used in the base station B1 for the same time-frequency resource as the base station B2. A method of transmitting signals to the mobile stations M1 and M2 will be described in detail.

First, in step S21, the base station B1 acquires long-term channel information of the downlink wireless communication link of the base station B1 to the mobile station M1 and the mobile station M2. The long-term channel information includes, but is not limited to, a mean matrix of a plurality of estimated values of a channel response matrix (or also referred to as a channel transfer matrix), or a covariance matrix; or a signal exit angle or angle of arrival.

For the case where the long-term channel information is a mean matrix of a plurality of estimated values of a channel response matrix (or also referred to as a channel transmission matrix), or a covariance matrix, step S21 can be further divided into sub-steps as shown in FIG.

First, in step S31, the base station B1 acquires a plurality of estimated values of its channel response matrix to the mobile station M1 and the mobile station M2.

Preferably, the channel response of the channel link of the base station B1 to their downlink wireless communication link can be estimated by the mobile station M1 and the mobile station M2, respectively, and the obtained estimated value is transmitted to the base station Bl. The mobile station M1 and the mobile station M2 can determine the estimated channel response of the channel link of the downlink wireless communication link by using a general downlink signal, and can also determine the channel link of the downlink wireless communication link by using some special reference signals. Estimated channel response. For example, for an OFDM system, the mobile station M1 and the mobile station M2 can determine an estimate of the channel response by using a pilot signal.

Since the base station B1 needs to obtain long-term channel information of its wireless communication link to the mobile station M1 and the mobile station M2, the mobile station M1 and the mobile station M2 need to estimate a plurality of channel response values. The multiple channel response values may be estimates of channel responses at different points in time. The estimated value may also be an estimated value of the channel response at different frequency points in the time-frequency resource that the base station B1 communicates with the mobile stations M1 and M2; or an estimated value of the channel response including a part of different time points and a part of the different frequency point An estimate of the channel response on. In the OFDM system, the mobile station M1 determines an estimated value of the channel response according to the pilot. FIG. 4 shows a schematic diagram of pilot allocation in the time-frequency resource block used by the base station B1 to communicate with the mobile station M1, where multiple pilots are used. The frequency is distributed over different OFDM symbols (time domain) and different subcarriers (frequency domain). The mobile station M1 can obtain a plurality of estimated values of the channel response based on the plurality of pilots shown in FIG. For another example, for a WiMAX wireless communication system, different time points may be multiple time points respectively located in multiple downlink frames.

For a wireless communication system with symmetric uplink and downlink channels, such as a time division multiplexing system, the estimated value of the channel response of the uplink wireless communication link estimated by the base station B1 through the uplink signal may also be approximated as an estimated value of the channel response of the downlink wireless communication link. . Similar to the method for the mobile station M1 to estimate the channel response of the downlink wireless communication link, the base station B1 can obtain the channel of the uplink wireless communication link by using an uplink signal including an ordinary service signal and an uplink sounding signal. The estimated value of the response. Preferably, base station B1 uses the uplink sounding signal to obtain an estimate of the channel response of the uplink wireless communication link. That is, step S31 can be further subdivided into two sub-steps S51 and S52 shown in Fig. 5.

In step S51, the base station B1 receives the uplink signals from the mobile station M1 and the mobile station M2, respectively.

In step S52, the base station B1 calculates a plurality of estimated values of its channel response matrix to the mobile station M1 and the mobile station M2 based on the received uplink signal.

Returning to Fig. 3, in step S32, the base station B1 calculates its mean matrix or covariance matrix after obtaining a plurality of estimated values of its channel response matrix to the mobile station M1. The same is true for mobile station M2.

Since the mean matrix or the covariance matrix of the channel response matrix is long-term channel information, which is a statistical value of a plurality of instantaneous channel information, in practice, how many pieces of instantaneous channel information are estimated to calculate a mean matrix or a covariance matrix, And how often to calculate the mean matrix or covariance matrix, depending on various performance parameters of the actual system.

Returning to FIG. 2, in step S22, the base station B1 is based on the obtained long-term channel information. And a predetermined rule for pre-processing the signals transmitted to the mobile station M1 and the mobile station M2 to obtain the pre-processed signal. For the network topology shown in Figure 1, the preprocessing is precoding processing. It is understood by those skilled in the art that the precoding mentioned in the present application specifically refers to a precoding matrix generated by using long-term channel information for spatially distinguishing multiple users or for spatially enhancing the power of a single user signal. The precoding made is different from MIMO precoding for a single user (eg STBC, etc.).

For precoding processing, predetermined rules include, but are not limited to, precoding rules based on covariance matrices of channel responses, beamforming rules based on signal exit angles or angles of arrival, and the like. Wherein, the precoding rules based on the covariance matrix of the channel response include singular value decomposition based on singular value decomposition, eigenvalue decomposition, etc., preferably including precoding rules based on singular value decomposition of the covariance matrix of the channel response.

For the precoding process, step S22 is subdivided into two sub-steps S61 and S62 as described in Fig. 6.

First, in step S61, the base station B1 determines the precoding coefficients of the two signals respectively transmitted to the mobile stations M1 and M2 on one or more transmitting antennas of the base station B1 based on the long-term channel information and the predetermined rule.

Then, in step S62, the base station B1 performs precoding processing on the two signals respectively sent to the mobile stations M1 and M2 according to the precoding coefficients determined in step S41, that is, performing weighting processing using precoding coefficients to obtain a warp. Precoded processed signal.

Returning to Fig. 2, finally, in step S23, the base station B1 transmits the precoded signal to the mobile station M1 and the mobile station M2 on the time-frequency resource agreed with the base station B2.

The method for transmitting signals to the mobile stations M1 and M2 on the same time-frequency resource as the base station B2 in the base station B1 is described in detail above.

For a better understanding of the present invention, the following is a case where the base station B1 and the base station B2 serve the mobile station M1 and the mobile station M2 in a cooperative MIMO operation manner and determine the precoding coefficient based on the singular value decomposition rule of the covariance matrix. Description.

Without loss of generality, the parameters of each base station and mobile station shown in FIG. 1 are as follows: - base stations B1, B2 have four transmit antennas, and each base station transmits two data streams to mobile stations M1 and M2; - The mobile stations M1, M2 each have two receiving antennas.

The meaning of each symbol to be mentioned below is explained below:

s _mn ( t ): a data symbol transmitted from the nth base station to the mth mobile station; wherein, the first base station is the base station B1, the second base station is the base station B2, and the first mobile station is the mobile station M1. The second mobile station is the mobile station M2.

x _m ( t ): the mth base station

H _mn : a channel response matrix from the nth base station to the mth mobile station;

W _mn : a precoding coefficient vector of a symbol transmitted by the nth base station to the mth mobile station on each antenna of the nth base station;

y _m (t): a symbol vector received in the mth mobile station;

n _m : additive white Gaussian noise vector received in the mth mobile station.

FIG. 7 is a schematic diagram of the signal processing in FIG. 1 at the present time. The above-mentioned downlink wireless communication link symmetric time division multiplexing system is taken as an example, and the base station B1 and the base station B2 respectively obtain multiple estimated values of the channel response through the uplink sounding signals. Of course, the mobile station M1 and the mobile station M2 can also measure the estimated channel response between the base station B1 and the base station B2 through the channel estimation module, and feed back to the base station B1 and the base station B2 through the uplink feedback channel.

The working process of the system shown in Figure 1 is described in detail below. Among them, the base station B1 is responsible for the coordinated MIMO scheduling work. The working process of the whole system can be divided into the following major steps:

Step 1: User grouping

The base station B1 divides the plurality of mobile stations it serves into two groups according to the strength of the uplink signals of the plurality of mobile stations served by the base station and the magnitude of the inter-cell interference received. The mobile stations in the first group are subject to less inter-cell interference and are located at the center of the cell. Therefore, only the base station B1 needs to communicate with them, and the single-user MIMO or multi-user MIMO can be used. The inter-cell interference received by the users in the second group is relatively large, located at the edge of the cell, and the base station B1 needs to communicate with them through coordinated MIMO to avoid or mitigate inter-cell interference. Specifically, the base station may determine the size of the inter-cell interference received by the mobile station according to the signal to noise ratio in the mobile station, or whether the signal strength is lower than a predetermined threshold. Scheduled value 08 001202

9 The selection can be set according to the size of the bit error rate in the mobile station. Similarly, the plurality of mobile stations served by the base station B2 are also divided into the above two groups.

Step 2: Inter-base station coordination MIMO mode signaling interaction

Taking the mobile station M1 and the mobile station M2 in the vicinity of the boundary of the coverage of the base station Bl and the base station B2 as an example, the base station B1 sends a request message to the base station B2 to request the base station B2 and the mobile station M2. For details on scheduling, refer to CN200710045052.0. After receiving the request from the base station B1, the base station B2 transmits an acknowledgment response message to the base station Bl. After receiving the acknowledgment message from the base station B2, the base station B1 starts its estimation process of the long-term channel information to the mobile station M1 and the mobile station M2. Similarly, base station B2 also initiates its estimation of long-term channel information to mobile station M1 and mobile station M2.

Step 3: Uplink detection signal transmission

Taking the base station B1 as an example of estimating the channel response from the uplink sounding signals from the mobile stations M1 and M2, the base station B1 transmits a request message requesting the mobile station M1 to transmit the uplink sounding signal to the mobile station M1. After receiving the request message, the mobile station M1 periodically transmits the uplink sounding signal sounding_signal 11 to the base station Bl. Similarly, the mobile station M2 periodically transmits an uplink sounding signal sounding a signall2 to the base station Bl. Similarly, for the base station B2, the mobile station M1 periodically transmits the uplink sounding signal sounding_signal 21 to the base station B2. Similarly, the mobile station M2 periodically transmits the uplink sounding signal sounding_signal22 to the base station B2. Preferably, the uplink sounding signals transmitted from the mobile station M1 and the mobile station M2 to the base station B1 are orthogonal in the time domain or in the frequency domain to avoid mutual interference of the sounding signals. Similarly, the uplink sounding signals transmitted from the mobile station M1 and the mobile station M2 to the base station B2 are orthogonal in the time domain or in the frequency domain to avoid mutual interference of the sounding signals.

Step 4: Estimation of the Covariance Matrix of the Channel Response Matrix

a) based on the received uplink sounding signal sounding_signal, the base station B1 estimates a plurality of estimated values {HuW-l of the channel response matrix of the downlink wireless communication link between the mobile station M1 and the mobile station M1, where K represents uplink sounding The number of training symbols in the signal, from a statistical point of view, that is, the number of samples of the channel response matrix. Since the base station B1 has 4 transmit antennas and the mobile station M1 has 2 receive antennas, the matrix { „ } is A matrix of 2 rows and ⁴ columns. Similarly, the base station based on the uplink sounding signal _S Bl sounding- ignal21 plurality estimation estimates the downlink channel wireless communications links between itself and the mobile station M2 response matrix value _{^. Lx (k), k} = \, ... , K} _a

b) Similarly, based on the received uplink sounding signals sounding_signal 12 and sounding_signal22, the base station B2 estimates a plurality of estimated values {H, ) of the channel response matrix of the downlink wireless communication link with the mobile stations M1 and M2, respectively. t = i,...,4

= i,..., }.

c) The base station B1 calculates a covariance matrix of the channel response R„ = (k)H _u (k), k = 1,..., }=丄 based on its plurality of estimated values of the channel response to the mobile station M1. Π (k)H (k) Similarly, the base station B1 calculates a covariance matrix R _2l = E{3⁄4 (A _:) H _{2l of the} channel response based on its plurality of estimated values of the channel response to the mobile station M2. ^ ), k = l,..., K} = ~ ^ H^ (k)H ₂ (k) d ) The base station B2 calculates the channel response based on its plurality of estimated values of the channel response to the mobile station M1 Covariance matrix R ₁₂ = E{5 ₂ (/ )H ₁₂ (k)

Similarly, base station B2 calculates a covariance matrix R _{22 of the} channel response based on its plurality of estimates of the channel response to mobile station M2.

Step 5: Calculation of the precoding coefficient vector

The base station B1 of the covariance matrix R _u perform singular value decomposition (SVD, Singular Value Decomposition) operation: Where ∑ is a 4×4 diagonal matrix, and the base station B1 determines the column vector of the matrix V corresponding to the column label of the largest element among the diagonal elements of the matrix according to the principle of maximizing the signal to noise ratio or the signal to interference and noise ratio. That is, the precoding coefficient vector W _n . Wn is a vector of 1 x 4 columns, which means the symbol _1⁄2 sent by the base station B1 to the mobile station M1 (the precoding coefficient of 0 on the 4 transmitting antennas of the base station B1. Similarly, the base station B1 performs matrix on the covariance matrix R ₂₁ The singular value decomposition obtains the symbol 3⁄4 transmitted by the base station B1 to the mobile station] VI2 (0 is the precoding coefficient W ₂₁ on the four transmitting antennas of the base station B1.

Similarly, the base station B2 performs matrix singular value decomposition on the covariance matrices R12 and R22 to obtain the symbol 3⁄4 transmitted by the base station B2 to the mobile station M1 (0 of 4 transmitting antennas at the base station B2) The precoding coefficients Wi _2, and a base station B2 transmits to the mobile station M2 is _¾ symbol (0 precoding coefficients in the four transmitting antennas of base station B2 W _22.

After the above step 5, the base stations B1 to be transmitted to the mobile station Ml and the symbol _½ M2 (0 and ¾ obtained based on the precoding coefficients (0 precoding vector to obtain x O-fw signals transmitted on respective antenna ,, W ₂₁ ]- where χ, Ο) is a vector of 1 X 4, each

The components correspond to the transmitted signals on each antenna. Similarly, the base station Β2 treats the precoding coefficients obtained therefrom to the mobile stations M1 and M2.

Coding to obtain the vector x ₂ (t) of the signal transmitted on each antenna

A vector of 1 x 4, each component corresponding to the transmitted signal on each antenna. Ideally, the beams formed by the base station B1 and the base station B2 are orthogonal, that is, the mobile station M1 does not receive the data stream transmitted to the mobile station M2, and the mobile station M2 does not receive the data stream transmitted to the mobile station M1. .

The signal y,(t) received by the mobile station can be written as y, ( -[H _n (t) H ₁₂ (t)]. + n, , similarly, based on a multiuser detector

The maximum likelihood principle or the principle of minimum mean square error, it is easy to demodulate from the equation to get the transmission symbol 1⁄2 (0 and (0.

Similarly, the signal y ₂ (t) received by mobile station M2 can be written as y ₂ ( = [H ₂₁ (t) H ₂₂ (t)]. + π, by maximum likelihood based on multiuser detector

W,,

Principle or minimum mean square error principle, it is easy to demodulate the transmitted symbols 3⁄4 (and _3⁄4 (t) from the equation. For details on demodulation according to the maximum likelihood principle, refer to Reference 1, and Reference 2. For details of demodulation according to the principle of minimum mean square error, reference can be made to Document 3. The present invention will not be described herein.

The long-term channel information is the covariance matrix of the channel response matrix, and the pre-coding coefficient is determined based on the singular value decomposition of the covariance matrix as an example. The base station B1 and the base station B2 are on the same time-frequency resource to the mobile station M1 and the mobile station. The process of transmitting signals by M2 is described in detail.

The following takes the long-term channel information as the signal departure angle or the angle of arrival as an example, the base station B1 and The process in which the base station B2 precodes the signal to be transmitted based on the signal leaving angle or the angle of arrival based on the beamforming rule will be described.

As shown in Fig. 8, the signal arrival angle (or direction of arrival) refers to the direction in which the radio wave reaches the antenna array. If the arriving radio wave satisfies the far-field narrowband condition, it can be approximated as a radio wave. The wavefront is a plane (generally, the communication between the mobile station and the base station at the edge of the cell satisfies the condition), and the angle between the array axis of the plane wavefront and the normal of the antenna array is the direction of arrival. For the base station B1, the signal arrival angle refers to the direction of arrival of the signal of the mobile station M1 with which it communicates, and the signal departure angle refers to the transmission direction of the signal transmitted by the base station B1 to the mobile station M1. For the mobile station M1, the signal arrival angle and the signal exit angle in the base station B1 are the same. How to estimate the signal arrival angle or the signal exit angle is well documented in the prior art, and the present invention will not be described again. For details, refer to Reference 4.

Without loss of generality, the spacing between the four antennas of the base station B1 is the same, for example, if the direction of the signal of the mobile station M1 reaching the base station B1 is, the precoding coefficient vector ^ can be determined, and the mobile station M2 is set. Signal arrives at the direction of base station B1

e

The angle is then determined by the precoding coefficient vector ₂₁ = as described above, the base station

- jln-ldx 'sin θ ₂ \

B1 is to be transmitted to the symbols (ί) and _{1⁄2 of the} mobile stations M1 and M2 according to the obtained precoding coefficients (precoding to obtain a vector of signals transmitted on the respective antennas)

Similarly, the spacing between the four antennas of the base station B2 is the same, both are d ₂ , and the direction angle of the signal of the mobile station M1 to the base station B2 is taken as an example, and the precoding coefficient can be determined.

1

Vector ₂ = , let the direction of the signal from the mobile station M2 reach the base station B1 as

e

-jln- i- -sin Θ ₁₂ It can be determined that the precoding coefficient vector w _{22 is} as described above, and the base station Β 2 is obtained according to

The resulting precoding coefficients are to be sent to the symbols _{3⁄4 of the} mobile stations M1 and M2 (0 and _3⁄4 (0 precoding to obtain the vector x ₂ of the signal transmitted on each antenna ₍ o = [w ₁₂ w ₂₂ ]T ^{1⁄2 (} "

L3⁄4 ( _ above is described by taking the long-term channel information as the channel arrival angle or the departure angle as an example, and the base station B1 and the base station B2 pre-code the signal to be transmitted according to the signal leaving angle or the angle of arrival.

It should be understood by those skilled in the art that the application of the present invention is not limited to the topology shown in FIG. 1, and may be applied to two base stations serving one or three or more mobiles on the same time-frequency resource. In the case of a station, three or more base stations serve one or more mobile stations on the same time-frequency resource; and the modes in which multiple base stations operate are not limited to the various modes mentioned above.

Taking two base stations serving a mobile station on the same time-frequency resource as an example, the two base stations can transmit signals to the mobile station in a macro diversity manner, and the base station can according to the downlink wireless communication chain between the mobile stations and the mobile station. The long-term channel information of the path determines the power of the transmitted signal. The two base stations may also jointly or separately transmit signals to the one mobile station on the same time-frequency resource in the form of closed-loop space-time coding, preferably, space-time block code. For the case of joint transmission, the weighting coefficients of the respective symbols in the closed-loop space-time coding can be determined according to the long-term channel information of the two base stations to the mobile station, for example, the mean matrix of the channel response matrix. Here, the closed loop means that the transmitting device performs weighting processing on the symbols of the space-time code to be transmitted using the long-term channel information. See Reference 5 for details on closed-loop space-time coding. The invention is not described herein again.

9 illustrates a cooperative transmission device for cooperatively transmitting signals to one or more mobile stations on the same time-frequency resource with other one or more base stations in a base station of a wireless communication network, in accordance with an embodiment of the present invention. Block diagram of 90. Those of ordinary skill in the art will appreciate that the wireless communication networks described herein include, but are not limited to, WiMAX networks, 3G networks, or next generation wireless mobile communication networks. Those skilled in the art should understand that the two base stations B1, B2 shown in Figure 1 are respectively located in adjacent cells or sectors. It should be noted that, at the edge of a cell, sometimes more than two base stations can communicate with mobile stations located at the cell edge, for example, for a widely used hexagonal cell coverage model, as shown in FIG. At the mobile station at the cell junction, it is possible for three base stations to communicate with the mobile station. Specifically, for a certain mobile station, selecting a few base stations and selecting which base stations to communicate with the mobile station are described in detail in the document CN200710045052.0, and the present invention is not described herein again.

For example, the case where the two base stations B1 and B2 shown in FIG. 1 serve two mobile stations M1 and M2 on the same time-frequency resource is used as an example, and the cooperative transmitting apparatus 90 located in the base station B1 is used with the base station B2. The process of transmitting signals to the mobile stations M1 and M2 on the same time-frequency resource is described in detail.

First, the obtaining means 91 acquires long-term channel information of the downlink wireless communication link of the base station B1 to the mobile station M1 and the mobile station M2. The long-term channel information includes, but is not limited to, a mean matrix of a plurality of estimated values of a channel response matrix (or also referred to as a channel transmission matrix), or a covariance matrix; or a signal exit angle or angle of arrival.

For the case where the long-term channel information is a mean matrix of a plurality of estimated values of a channel response matrix (or also referred to as a channel transfer matrix), or a covariance matrix, the functions of the obtaining means 91 can be respectively obtained by the two shown in FIG. The sub-device channel response obtaining means 911 and the first determining means 912 are completed.

First, the channel response acquiring means 911 acquires a plurality of estimated values of its channel response matrix to the mobile station M1 and the mobile station M2.

Preferably, the channel response of the channel link of the base station B1 to their downlink wireless communication link can be estimated by the mobile station M1 and the mobile station M2, respectively, and the obtained estimated value is transmitted to the channel response acquiring means 911. The mobile station M1 and the mobile station M2 can determine the estimated channel response of the channel link of the downlink wireless communication link by using a general downlink signal, and can also determine the channel link of the downlink wireless communication link by using some special reference signals. Estimated channel response. For example, for an OFDM system, the mobile station M1 and the mobile station M2 can determine an estimate of the channel response by the pilot signal.

Since the acquisition device 91 needs to obtain its wireless communication to the mobile station M1 and the mobile station M2 The long-term channel information of the link, therefore, the mobile station M1 and the mobile station M2 need to estimate a plurality of channel response values. The plurality of channel response values may be estimated values of channel responses at different time points, or may be estimated values of channel responses at different frequency points in time-frequency resources communicated by the base station B1 with the mobile stations M1 and M2; An estimate of the channel response, including portions of the time, and an estimate of the channel response at a portion of the different frequency points. The estimation result of the channel response is determined by the mobile station M1 according to the pilot in the OFDM system. FIG. 4 is a schematic diagram of pilot allocation in the time-frequency resource block used by the base station B1 to communicate with the mobile station M1, where multiple pilots are used. The frequency is distributed over different OFDM symbols (time domain) and different subcarriers (frequency domain). The mobile station M1 can obtain a plurality of estimated values of the channel response based on the plurality of pilots shown in FIG. For another example, for a WiMAX wireless communication system, different time points may be multiple time points respectively located in multiple downlink frames.

For a wireless communication system with symmetric uplink and downlink channels, such as a time division multiplexing system, the estimated value of the channel response of the uplink wireless communication link estimated by the base station B1 through the uplink signal may also be approximated as an estimated value of the channel response of the downlink wireless communication link. . Similar to the method for the mobile station M1 to estimate the channel response of the downlink wireless communication link, the channel response acquiring means 911 can obtain the uplink wireless communication link by using a general uplink signal, including a normal service signal and an uplink sounding signal. Estimated value of the channel response. Preferably, the uplink sounding signal is utilized to obtain an estimate of the channel response of the uplink wireless communication link. At this time, the function of the channel response acquiring means 911 can be completed by the two sub-device receiving means 9111 and the computing means 9112 shown in FIG.

First, the receiving device 9111 receives the uplink signals from the mobile station M1 and the mobile station M2, respectively.

Then, computing device 9112 calculates a plurality of estimated values of its channel response matrix to mobile station M1 and mobile station M2 based on the received uplink signal.

After the channel response obtaining means 911 acquires a plurality of estimated values of the channel response matrix of the base station B1 to the mobile station M1, the first determining means 912 determines the mean matrix or covariance matrix of the channel response matrix. The same is true for mobile station M2.

Since the mean matrix or covariance matrix of the channel response matrix is long-term channel information, which is the statistical value of multiple instantaneous channel information, in practice, how many instantaneous channel information are estimated The value is a sample to calculate the mean matrix or covariance matrix, and how long to calculate the mean matrix or covariance matrix, which can be determined by various performance parameters of the actual system.

After the obtaining means 91 obtains the long-term channel information, the pre-processing means 92 pre-processes the signals transmitted by the base station B1 to the mobile station M1 and the mobile station M2 based on the obtained long-term channel information and a predetermined rule to obtain a pre-processed After the signal. For the network topology shown in Figure 1, the preprocessing is precoding. It is understood by those skilled in the art that the precoding mentioned in the present application specifically refers to a precoding matrix generated by using long-term channel information for spatially distinguishing multiple users or for spatially enhancing the power of a single user signal. The precoding made is different from MIMO precoding for a single user (eg STBC, etc.).

For precoding processing, predetermined rules include, but are not limited to, precoding rules based on covariance matrices of channel responses, beamforming rules based on signal exit angles or angles of arrival, and the like. The precoding rules based on the covariance matrix of the channel response include singular value decomposition, eigenvalue decomposition, and the like. Precoding rules based on singular value decomposition of the covariance matrix of the channel response are preferably included.

For the precoding process, the functions of the preprocessing device 92 can be performed by the two sub device second determining devices 921 and the precoding processing device 922 shown in Fig. 12, respectively.

First, the second determining means 921 determines the precoding coefficients of the two signals respectively transmitted to the mobile stations M1 and M2 on one or more transmitting antennas of the base station B1 based on the long-term channel information and the predetermined rule.

Then, the precoding device 922 performs precoding processing on the two signals respectively transmitted to the mobile stations M1 and M2 according to the precoding coefficients determined in step S41, that is, performing weighting processing using the precoding coefficients to obtain the precoding process. signal of.

After the pre-processing device 92 obtains the pre-processed signal, the transmitting device 93 transmits the pre-coded signal to the mobile station M1 and the mobile station M2 on the time-frequency resource agreed with the base station B2.

The process of transmitting signals to the mobile stations M 1 and M 2 on the same time-frequency resource of the cooperative transmission device 90 and the base station B2 located at the base station B1 is described in detail above.

In order to better understand the working process of the cooperative transmitting apparatus 90 in the present invention, the following In a base station Bl and a base station B2 in FIG synergistic MIMO operating way to serve the mobile station Ml and the mobile station M ^2, based on singular value decomposition rules covariance matrix by means of the coordinated transmission within a base station B1 and base station B2 90 The case of determining the precoding coefficient will be described in detail.

Without loss of generality, the parameters of each base station and mobile station shown in FIG. 1 are as follows: - base stations Bl, B2 respectively have four transmit antennas, and each base station transmits two data streams to mobile stations M1 and M2;

- The mobile stations Ml, M2 each have two receiving antennas.

The meaning of each symbol to be mentioned below is explained below:

s _mn ( t ): a data symbol transmitted from the nth base station to the mth mobile station; wherein, the first base station is the base station B1, the second base station is the base station B2, and the first mobile station is the mobile station M1, The second mobile station is the mobile station M2.

x _m ( t ): the mth base station

y _m (t): a symbol vector received in the mth mobile station;

n _m : additive white Gaussian noise vector received in the mth mobile station.

FIG. 7 is a schematic diagram of the signal processing in FIG. 1 at this time. The above-mentioned downlink wireless communication link symmetric time division multiplexing system is taken as an example, and the channel response acquiring device 911 in the base station B1 and the base station B2 respectively obtain the uplink detection signal. A plurality of estimated values of the channel response; of course, the channel estimation module of the mobile station M1 and the mobile station M2 can also measure the estimated channel response between the base station B1 and the base station B2, and feedback to the uplink feedback channel through the uplink feedback channel. The channel response acquisition means 911 in the base station B1 and the base station B2.

Step 1: User grouping

The base station B1 is based on the strength and the uplink of the uplink signals of the plurality of mobile stations it serves. The size of the inter-cell interference is to divide the multiple mobile stations it serves into two groups. The mobile stations in the first group are subject to less inter-cell interference and are located in the center of the cell. Therefore, only the base station B1 needs to communicate with them, and the single-user MIMO or multi-user MIMO can be used. The users in the second group receive large inter-cell interference, located at the edge of the cell, and the base station B1 needs to communicate with them through coordinated MIMO to avoid or mitigate inter-cell interference. Specifically, the base station may determine the size of the inter-cell interference received by the mobile station according to the signal to noise ratio in the mobile station, or whether the signal strength is lower than a predetermined sound value. The selection of the predetermined threshold can be set according to the size of the bit error rate in the mobile station. Similarly, the plurality of mobile stations served by the base station B2 are also divided into the above two groups.

Step 2: Inter-base station coordination MIMO mode signaling interaction

Taking the mobile station M1 and the mobile station M2 in the vicinity of the boundary of the coverage of the base station B1 and the base station B2, the base station B1 sends a request message to the base station B2 to request the base station B2 and the mobile station M2. For details on scheduling, refer to CN200710045052.0. After receiving the request from the base station B1, the base station B2 transmits an acknowledgment response message to the base station Bl. After receiving the acknowledgment message from the base station B2, the base station B1 starts its estimation process of the long-term channel information to the mobile station M1 and the mobile station M2. Similarly, base station B 2 also initiates its estimation of long-term channel information to mobile station M 1 and mobile station M2.

Step 3: Uplink detection signal transmission

Taking the base station B1 as an example of estimating the channel response from the uplink sounding signals from the mobile stations M1 and M2, the base station B1 transmits a request message requesting the mobile station M1 to transmit the uplink sounding signal to refer to the mobile station M1. After receiving the request message, the mobile station M1 periodically transmits the uplink sounding signal sounding_signal 11 to the base station Bl. Similarly, the mobile station M2 periodically transmits the uplink sounding signal sounding_signal2 to the base station Bl. Similarly, for the base station B2, the mobile station M1 periodically transmits the uplink sounding signal sounding_signal 21 to the base station B2. Similarly, the mobile station M2 periodically transmits the uplink sounding signal sounding_signal22 to the base station B2. Preferably, the uplink sounding signals transmitted from the mobile station] M1 and the mobile station M2 to the base station B1 are orthogonal in the time domain or in the frequency domain to avoid mutual interference of the sounding signals. Similarly, it is transmitted from the mobile station M1 and the mobile station M2 to the base station B2. N2008/001202

19 The uplink sounding signals are orthogonal in the time domain or in the frequency domain to avoid mutual interference of the sounding signals.

Step 4: Estimation of the Covariance Matrix of the Channel Response Matrix

a) based on the uplink sounding signal sounding_signal received by the receiving device 9111, the computing device 9112 in the base station B1 calculates a plurality of estimated values of the channel response matrix of the downlink wireless communication link between the base station B1 and the mobile station M1 { u = u}, where K represents the number of training symbols in the uplink sounding signal, from a statistical point of view, that is, the number of samples of the channel response matrix. Since the base station B1 has 4^ transmit antennas and the mobile station M1 has 2 receive antennas, the matrix is a matrix of 2 rows and 4 columns. Similarly, the computing device 9112 estimates a plurality of estimated values of the channel response matrix of the downlink wireless communication link between the mobile station M2 and the mobile station M2 based on the uplink sounding signal sounding_signal21 received by the receiving device 9111 {H ₂₁ (/5:), D }.

b) Similarly, based on the uplink sounding signals sounding_signall2 and sounding_signal22 received by the receiving device 9111, the computing device 9112 in the base station B2 calculates a plurality of channel response matrices of the downlink wireless communication link of the base station B2 and the mobile stations M1 and M2, respectively. Estimated value {H ₁₂ ( : = i,,..,4, {n ₂₂ (k),k = \,...,K}.

c) The first determining means 912 in the base station B1 determines the covariance matrix of the channel response R _n = E{H^WH _n W, ^l, according to a plurality of estimated values of the channel responses of the base station B1 to the mobile station M1. ..^}=^∑H^WH _u W; Similarly, the first determining means 912 determines a covariance matrix of the channel response R ₂₁ = E{3⁄4 according to a plurality of estimated values of the channel responses of the base station B1 to the mobile station Μ2. (:)H ₂₁ (k), k = l,...,K} = ^ _j (^)H _2] (k). d) The first determining means 912 in the base station B2 determines the covariance matrix of the channel response R ₁₂ = E{ (/t) ii ₁₂ , l, according to a plurality of estimated values of the channel responses of the base station B2 to the mobile station M1. .., 4 = _i;; Similarly, a plurality of estimates in response to the first determining means 912 according to the channel base station B2 to the mobile station M2 to determine the channel response covariance matrix _{_{R 22 = E {R ^ 2}} (k) U ₂₂ (k), k = i,..., K} = ^∑H^ ₂ (k) ₂₂ (k). Step 5: Calculation of the precoding coefficient vector

The base station apparatus B1 in the second 921 pairs of determining a covariance matrix R _u performs matrix Singular SVD, Singular Value Decomposition operation: R _U =U∑VH. Wherein, ∑ is a 4×4 diagonal matrix, and the second determining means 921 determines the matrix V corresponding to the column label of the largest element among the diagonal elements of the matrix according to the principle of maximizing the signal-to-noise ratio or the signal-to-interference noise ratio. The column vector is the precoding coefficient vector W _n . W _n is a vector of 1 X 4 columns, which means a symbol transmitted by the base station B1 to the mobile station M1 (a precoding coefficient of 0 on the four transmitting antennas of the base station B1. Similarly, the second determining means 921 pairs the covariance matrix R ₂₁ performs matrix singular value decomposition to obtain a symbol 3⁄4 (0 is a precoding coefficient W ₂₁ on the four transmitting antennas of the base station B1) that the base station B1 transmits to the mobile station M2.

Similarly, the base station B2 in the second determining means 921 pairs of the covariance matrix for R12 and R22 (0 precoding coefficients matrix singular value decomposition base station B2 to the mobile station Ml and _¾ symbols on four transmitting antennas of base station B2 W _12, and the base station B2 transmits to the mobile station M2 is _¾ symbol (0 precoding coefficients in the four transmitting antennas of base station B2 W _22.

After above five steps, a pre-coding processing apparatus base station B1 922 treated according to the precoding coefficient obtained is transmitted to the mobile station Ml and M2 symbols _½ (0 and ¾ (0 precoded obtained signals transmitted on respective antennas Vector c )-

x _{i (} t) is a vector of 1 x 4, and each component corresponds to a transmitted signal on each antenna. Similarly, the base station B2 sends the symbols to be transmitted to the mobile stations M1 and M2 according to the precoding coefficients obtained therefrom (0 and 3⁄4 (0 precoding to obtain a vector of signals transmitted on the respective antennas)

1⁄2 (0

3⁄4( = [W ₁₂ W ₂₂ ]. where χ ₂ () is a vector of 1 x 4, each component corresponding to each

1⁄2( .

The transmit signal on the antenna. Ideally, the beams formed by the base station B1 and the base station B2 are orthogonal, that is, the mobile station M1 does not receive the data stream transmitted to the mobile station M2, and the mobile M1 does not receive the data stream transmitted to the mobile station M1. .

The signal y received by the mobile station M1, (0 can be written as y, ( = [H _n ( Η ₁₂ ( )- similarly, by the principle of maximum likelihood based on multi-user detector or the principle of minimum mean square error, it is easy to The demodulation in the equation gives the transmitted symbols 1⁄2 (0 and 1⁄2 (0.

Similarly, the signal y ₂ (0 can be written by the mobile station Μ2 _{_{y 2 (-. [H 21}} (t) H 22 (t)] + n 2 0 based on the maximum likelihood principle or a multiuser detection principle of minimum mean square error, the formula is easily obtained from demodulating transmitted symbol _{¾ (0} and 3⁄4 (0. For details on demodulation according to the maximum likelihood principle, refer to Reference 1 and Reference ^{2. For} details on demodulation according to the principle of minimum mean square error, refer to Reference 3.

The cooperative transmission device 90 uses the long-term channel information as the covariance matrix of the channel response matrix, and determines the pre-coding coefficient based on the singular value decomposition of the covariance matrix as an example to move the base station B1 and the base station B2 on the same time-frequency resource. The process of transmitting signals by station M1 and mobile station M2 is described in detail.

In the following, taking the long-term channel information as the signal leaving angle or the angle of arrival as an example, the cooperative transmitting apparatus 90 in the base station B1 and the base station B2 will be described based on the signal leaving angle or the angle of arrival and precoding the signal to be transmitted based on the beamforming rule.

As shown in Fig. 8, the signal arrival angle (or direction of arrival) refers to the direction in which the radio wave reaches the antenna array. If the arriving radio wave satisfies the far-field narrowband condition, it can be approximated as a radio wave. The wavefront is a plane (generally, the communication between the mobile station and the base station at the edge of the cell satisfies the condition), and the angle between the array axis of the plane wavefront and the normal of the antenna array is the direction of arrival. For the base station B1, the signal arrival angle refers to the direction of arrival of the signal of the mobile station M1 with which it communicates, and the signal departure angle refers to the transmission direction of the signal transmitted by the base station B1 to the mobile station M1. For the mobile station M1, the signal arrival angle and the signal exit angle in the base station B1 are the same. How to estimate the signal arrival angle or the signal exit angle has been described in the prior art, and the present invention will not be described again. For details, refer to Reference ⁴ .

Taking the same distance between the four antennas of the base station B1 as an example, if the direction of the signal of the mobile station M1 reaches the base station B1, the second determining means 921 in the base station B1 can determine the precoding coefficient vector ^= , set the signal of the mobile station Μ 2 to arrive

The direction angle of the base station B1 is, then the second determining means 921 can determine the precoding coefficient vector 1

As described above, the precoding processing means 922 in the base station Bl is to be transmitted to the mobile stations M1 and M2 based on the obtained precoding coefficients «precoding to obtain a vector of signals transmitted on the respective antennas

Similarly, the distance between the four antennas of the base station Β2 is the same, and both are d ₂ as an example. Let the direction of the signal of the mobile station M1 reach the base station B2 be the second e of the base station B21.

The determining means 921 can determine the precoding coefficient vector =, and the second determining means 921 can determine the precoding processing means 922 in the precoding coefficient vector ₂₂ base station B2 if the direction of the signal of the mobile station M2 reaches the base station B1.

Symbols (t) and _1⁄2 to be transmitted to the mobile stations M1 and M2 according to the obtained precoding coefficients (precoding to obtain a vector of signals transmitted on the respective antennas)

3⁄4 ( = [W ₁₂ W ₂₂ ]. 3⁄4 (0

1⁄2 (

The above is a description of the process in which the base station B1 and the base station B2 precode the signal to be transmitted according to the signal exit angle or the angle of arrival, taking the long-term channel information as the channel arrival angle or the exit angle as an example.

It should be understood by those skilled in the art that the application of the cooperative transmitting apparatus 90 in the present invention is not limited to the topology shown in FIG. 1, and may be applied to two base stations serving one or three on the same time-frequency resource. In the case of even more mobile stations, three or more base stations serve one or more mobile stations on the same time-frequency resource; and the modes in which multiple base stations operate are not limited to the above Various modes.

Taking two base stations serving a mobile station on the same time-frequency resource as an example, the cooperative transmitting device 90 in the two base stations may send a signal to the mobile station in a macro diversity manner, and the pre-processing device 92 in the base station may be configured according to Its downstream wireless communication link to the mobile station The long-term channel information determines the power of the transmitted signal. The cooperative transmitting device 90 of the two base stations may also jointly or separately transmit signals to the one mobile station on the same time-frequency resource in the form of closed-loop space-time coding, preferably a space-time block code. For the case of joint transmission, the pre-processing means 92 may according to the long-term channel information of the two base stations to the mobile station, the weight coefficient. Here, the closed loop means that the transmitting device performs weighting processing on the symbols of the space-time code to be transmitted using the long-term channel information. See Reference 5 for details on closed-loop space-time coding. The invention is not described herein again.

The specific embodiments of the present invention have been described above. It is to be understood that the invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the appended claims.

Attachment: References

1. G. Awater, A. van Zelst, R. van Nee. Reduced complexity space division multiplexing receivers. Proceedings of IEEE Vehicular Technology Conf., vol. 1, Tokyo, Japan, May, 2000. 11 15;

4. Efficient near-ML detection for MIMO channels: the sphere-projection algorithm. Seethaler, D.; Artes, H.; Hlawatsch, F.. Global Telecommunications Conference, 2003. GLOBECOM '03. IEEE. Volume 4, 1-5 Dec. 2003 Page(s): 2089 2093;

3. B. A. Bjecke, J. G. Proakis. Multiple transmit and receive antenna diversity techniques for wireless communications. Proceedings of IEEE

Adaptive Systems Signal Processing, Communications, Control Symp., Lake Louise, AB, Canada, October, 2000. 70 75;

4. MIMO-related Technologies and Applications, pp. 188-199, edited by Huang Wei, Yuan Chaowei, Yang Ruizhe and Liu Ming, January 2007;

5. Closed-loop space time block coding techniques for OFDM broadband wireless access systems, Lambotharan, S.; Toker, C., IEEE Transactions on Consumer Electronics, Volume 51 , Issue 3, Aug. 2005 Page(s): 765- 769 .

Attachment: Patent application CN ² 00710045052. 0 full text and drawing of the specification, multi-base station cooperative MIMO with low information interaction and its scheduling method and device

The present invention relates to inter-cell interference suppression in a wireless communication network, and more particularly to a method and apparatus for inter-cell interference suppression by MIMO (Multiple Input Multiple Output) wireless transmission coordinated by multiple base stations in a wireless communication network. Background technique

In a wireless communication network using frequency resource multiplexing, inter-cell interference caused by the frequency reuse is an important factor that restricts downlink capacity. For a mobile terminal located at the cell edge (ie, the area between adjacent cells), while receiving the useful signal from the base station to which it belongs, it also receives signals from other base stations using the same time-frequency resource. The signals of other base stations constitute interference to the mobile terminal.

In the OFDM (Orthogonal Frequency Division Multiplexing) / OJFDMA (Orthogonal Frequency Division Multiple Access) system, in order to solve the above problems, the following two solutions requiring multi-base station cooperation are available:

Macro diversity

Based on the macro diversity scheme, for a mobile terminal moving to the cell edge, the base station to which it belongs and the base station to which it is moving use the same time-frequency resource (time slot and subcarrier) to transmit the same signal to the mobile terminal. Thus, interference between adjacent cells is suppressed, and diversity gain can be obtained due to independence between the base stations on the transmission channel.

The drawback of the macrodiversity scheme is that it requires neighboring base stations to transmit the same signal to the same terminal using the same time-frequency resources, so that the total number of users that the system can support is limited.

2. Network MIMO

Based on network MIMO, all antennas of all base stations are regarded as one transmit antenna array, and precoding matrices are generated according to all channel state information CSI (for example, channel response matrix) between all base stations and mobile terminals, thereby realizing joint between multiple base stations. Precoding to eliminate Co-channel interference (CCI) between multiple users. Since the joint precoding of the technology considers the CSI between all base stations and all mobile terminals, theoretically, network MIMO minimizes the interference caused by time-frequency resource multiplexing, and the performance is optimal.

The cost of obtaining excellent performance is very high in computational complexity. More seriously, because each base station needs to be in the Backhaul network (backhaul network, mainly used for data and information between each base station and between the base station and the dispatching device). The interactions are exchanged for their respective related channel information. The Backhaul network resources consumed by the transmission of a large amount of information are high, which increases the burden on the Backhaul network, and the transmission delay of such information may cause system performance to degrade.

Therefore, a new solution is needed to solve the above problems in the prior art, and the solution should effectively prevent the above-mentioned interference, and avoid introducing excessive Backhaul network resource requirements for the system, and have low computational complexity. . Summary of the invention

To achieve the above object, the present invention provides a low-information multi-base station cooperative MIMO and a scheduling method and apparatus thereof for a wireless communication network, wherein:

- multiple base stations can use the same time-frequency resources to serve the same mobile terminal in MIMO mode;

- a base station can use the same time-frequency resources and use SDMA to simultaneously serve multiple mobile terminals;

- when a base station needs to serve multiple mobile terminals on one time-frequency resource without interference cancellation for other mobile terminals; or one base station needs to serve one or more mobile terminals on one time-frequency resource and simultaneously to the other or When a plurality of mobile terminals perform interference cancellation, the base station needs to perform precoding on the data to be transmitted. A mobile terminal served by the base station and performing interference cancellation is a mobile terminal associated with the base station. In particular, according to the present invention, the precoding matrix generation process at each base station that needs to perform precoding is independent of each other and is completed inside each base station, that is, each base station only needs to know the corresponding time frequency resource determined by the scheduling device. The CSI between the mobile terminal that needs to be served by the base station and the interference cancellation required by the base station and the base station (specifically, the channel estimation by the base station or the mobile terminal based The feedback of the end), the precoding matrix can be calculated;

- When a base station only needs to serve the mobile terminal on one time-frequency resource and does not need to perform interference cancellation on any mobile terminal, no precoding is required. It is understood by those skilled in the art that the precoding mentioned in the present application specifically refers to precoding by using a precoding matrix for spatially distinguishing multiple users generated based on channel state information, unlike MIMO for a single user. Precoding (eg STBC, etc.:).

- Whether a mobile terminal is jointly served by a plurality of cooperative base stations, whether a base station needs to serve multiple mobile terminals or eliminates interference, etc., by a scheduling device (specifically, a device for performing a scheduling function on a scheduling device) /module) to determine.

The scheduling device can be either a network device independent of the base station or integrated into a certain base station.

The scheduling device schedules MIMO communication between the base station and the mobile terminal as follows:

The base station obtains signal quality related information between it and nearby mobile terminals and reports it to the scheduling device to which it belongs. The base station reports the signal quality related information indicating that the mobile terminal is about to perform handover and the corresponding mobile terminal identification information to the scheduling device, and may also report signal quality related information indicating that the signal quality exceeds the fourth predetermined alarm value and the corresponding mobile terminal. Identification information.

Then, the scheduling device selects, for each mobile terminal, a base station for which the downlink signal is transmitted for each mobile terminal according to the signal quality related information reported by each coordinated base station under its jurisdiction (hereinafter referred to as a serving base station, for a mobile terminal, the serving base station may be one And may also be multiple), and if necessary, which base station needs to perform interference cancellation on which time-frequency resource, and notify the corresponding base station of the scheduling result, and the scheduling device also needs to control according to the scheduling result. The service data addressed to each mobile terminal is correspondingly sent to its serving base station.

Thereafter, each base station determines which mobile terminals are served according to the scheduling result of the scheduling device, and performs necessary interference cancellation on which terminals. Each base station then calculates the precoding matrix and generates a transmission signal using the CSI between the mobile terminal and the base station that it needs to service and cancel the interference. According to a first aspect of the present invention, a method for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations within a coordination area governed by the scheduling device in a scheduling device of a wireless communication network is provided The method includes the following steps: a. acquiring signal quality related information between the multiple cooperative base stations and multiple mobile terminals in the vicinity thereof; b. when signal quality related information related to one mobile terminal indicates multiple optimalities When the difference between the signal qualities is lower than a first predetermined threshold, indicating that at least two of the plurality of base stations related to the plurality of optimal signal qualities use the same time frequency as the serving base station of the mobile terminal The resource sends a downstream signal to it.

According to a second aspect of the present invention, a method for performing MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network is provided, wherein the method includes the following steps: A. obtaining the base station and its vicinity Signal quality related information between each mobile terminal; B. acquiring indication information related to the base station, the indication information is used to indicate a mobile terminal associated with the base station; C. when the indication information indicates the When the mobile terminal associated with the base station includes a plurality of mobile terminals to which a downlink signal is to be transmitted by the base station using the same time-frequency resource, a precoding is generated according to channel state information between the base station and the plurality of mobile terminals. a matrix; D. precoding the traffic data to be sent to the plurality of mobile terminals using the precoding matrix to generate a precoded downlink signal to be sent to the plurality of mobile terminals.

Correspondingly, when the indication information indicates that the mobile terminal associated with the base station includes a mobile terminal to which a downlink signal is to be transmitted by the base station and a mobile terminal to be interfered by the base station, the base station will The channel state information between the mobile terminal to which the base station is to be sent a downlink signal and the channel state information between the mobile terminal and the mobile terminal to be interfered by the base station are generated to generate the pre- Encoding matrix.

According to a third aspect of the present invention, there is provided a scheduling apparatus for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations under the jurisdiction of the scheduling device in a scheduling device of a wireless communication network, where The method includes: a signal shield quantity acquiring apparatus, configured to acquire signal quality related information between the plurality of cooperative base stations and a plurality of mobile terminals in the vicinity thereof; and first indication means, configured to be related to signal quality related to a mobile terminal The information indicates that the difference between the plurality of optimal signal qualities is lower than a first predetermined At the threshold, at least two of the plurality of base stations indicating the plurality of optimal signal qualities are used as the serving base station of the mobile terminal to transmit downlink signals thereto using the same time-frequency resource.

According to a fourth aspect of the present invention, there is provided a communication apparatus for performing MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network, comprising: signal quality obtaining means for obtaining the base station and Signal quality related information between the respective mobile terminals; the indication information acquiring means acquires indication information related to the base station, the indication information is used to indicate a mobile terminal associated with the base station; When the indication information indicates that the mobile terminal associated with the base station includes multiple mobile terminals to which a downlink signal is to be sent by the base station using the same time-frequency resource, according to the base station and the multiple mobile terminals Inter-channel state information generates a pre-coding matrix; precoding means is configured to pre-code the service data to be sent to the plurality of mobile terminals by using the pre-coding matrix to generate a to-be-sent to the plurality of mobile terminals Precoded downstream signal.

The technical solutions provided by the present invention include but are not limited to the following advantages:

1. Effective suppression of inter-cell interference is achieved;

2. Since one or more base stations can serve multiple users on the same time-frequency resource and suppress interference between users, the throughput of the system is improved;

3. The information used for scheduling in the present invention does not occupy more resources on the Backhaul network. Because, if the signal quality related information uses information such as RSSI, CQI and the channel response matrix H (a multi-dimensional complex matrix) transmitted on the Backhaul network where the network MIMO is located, the amount of data is very small, and since the base station can preferably only The signal quality related information between the mobile terminal and the mobile terminal is selected and reported to the scheduling device, so that the resource occupation on the Backhaul network can be further reduced; the transmission of the scheduling result also requires only a small amount of Backhaul network resources.

4. In the present invention, the amount of calculation by the base station to generate the precoding matrix is small. Since the precoding is performed independently by each base station, for a base station, it only needs to self-measure to obtain channel state information between the associated mobile terminal and the base station itself notified by the scheduling device for precoding. The precoding performed does not involve the non-associated mobile terminal and the base station The channel state information between the bodies is not related to channel state information between other base stations and mobile terminals associated with the other base stations. DRAWINGS

Other features, objects, and advantages of the invention will become apparent from the Detailed Description of Description

1 is a schematic diagram of a wireless communication network for supporting scheduling of communication between a mobile terminal and a base station according to an embodiment of the present invention;

2 is a flow chart of a method for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations in a cooperation area under the jurisdiction of the scheduling device in a scheduling device of a wireless communication network according to an embodiment of the present invention. Figure

3 is a flowchart of a method for performing MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network, in accordance with an embodiment of the present invention;

4 is a scheduling apparatus for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations within a cooperation area under the jurisdiction of the scheduling device in a scheduling device of a wireless communication network, in accordance with an embodiment of the present invention. Block diagram

5 is a block diagram of a communication device for performing MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network, in accordance with an embodiment of the present invention; FIG. 6 is a diagram for performing in accordance with an embodiment of the present invention. Schematic diagram of multi-base station cooperative MIMO with low information interaction and its scheduling.

1 is a schematic diagram of a wireless communication network for supporting scheduling of communications between a mobile terminal and a base station in accordance with an embodiment of the present invention. Those skilled in the art can understand that the network shown can be a WiMAX network, a 3G network or a next-generation wireless mobile communication network, and is not limited thereto. Hereinafter, each base station (that is, each base station connected to a scheduling device) in a cooperation area under one scheduling device is referred to as a cooperative base station, such as Base stations a, b, c shown in Fig. 1. The scheduling device can be a network device independent of each base station or directly integrated in a certain base station. Those skilled in the art understand that the scheduling device is not limited to an independent network device or a base station, and may also be a network device dedicated to performing the scheduling scheme provided by the present invention.

The invention will be described from a system perspective in conjunction with FIG. 1 as follows:

First, each base station obtains signal quality related information between it and each mobile terminal in the vicinity. The signal quality related information such as RS SI is a received signal strength indication or CQI, that is, a channel quality indicator or CSI, that is, channel state information (e.g., instantaneous or long-term channel response). Taking RSSI as an example, the way in which a base station obtains signal quality related information includes:

- the base station commands each mobile terminal in its vicinity to transmit a Soimding signal to the base station by using a specific time-frequency resource, and the base station then measures the quality of the Soimding signal to obtain corresponding signal quality related information;

- the base station transmits a signal (such as a pilot signal, etc.) exclusively for the terminal to perform signal quality measurement to each mobile terminal in the vicinity thereof, and the mobile terminal then feeds the measured signal quality related information to the corresponding base station;

- The base station directly measures the signal quality related information obtained from the uplink traffic (Uplink Traffic) signal of the mobile terminal.

Those skilled in the art can understand that since the signal quality related information obtained by each base station needs to be transmitted on the Backhaul network to be aggregated to the scheduling device, the signal quality related information itself should preferably have a small amount of data compared with The channel response matrix H, RSSI or CQI, which has a large amount of data, is preferred signal quality related information because it is only a simple value.

Subsequently, each base station reports its obtained signal quality related information (hereinafter, RSSI as an example) to the scheduling device D through the Backhaul network. The base station may report all the RSSIs collected by the base station to the scheduling device D according to the identification information (ID) of the corresponding mobile terminal without screening; or may select those indicating the signal quality higher than one of all the RSSIs. The RSSI of the fourth predetermined threshold and the RSSI indicating that the mobile terminal is about to perform handover are reported along with the feature information of the corresponding mobile terminal. Because other RSSIs indicating poor signal quality are just useless in the scheduling process at scheduling device D. According to. In this way, the pressure on the Backhaul network can be further reduced to some extent. In this example, it is assumed that each base station reports all the RSSIs it collects to the scheduling device D, and assumes that the RSSI summarized to the scheduling device D includes the RSSS between each coordinated base station in FIG. 1 and each mobile terminal in FIG.

Thereafter, the scheduling device D analyzes the aggregated RSSI to schedule MIMO communication between the cooperative base stations and the mobile terminal, without loss of generality for the scheduling device D. The RSSI-based scheduling strategy is as follows:

- when the RSSI indicates the signal quality between a mobile terminal and the base stations a, bc (abbreviated as S _x , where X is the corresponding reference number of the base station), the relationship is S _a > S _b > S _c , and S _a - S _b <The first predetermined threshold (TH1), and S _a - S _C >TH1, then the scheduling device D instructs the base stations a, b to jointly serve the mobile terminal in MIMO mode using the same time-frequency resource (such as T1F1). It is assumed that the mobile terminal 0 satisfies the above conditions, and its serving base station is the base stations a, b.

Those skilled in the art understand that when S _a > S _b > S _c and S _a - S _C < TH1, the scheduling device D can be based on the space division capability of each base station and the receiving capability of the mobile terminal (eg, the number of receiving antennas, etc.) Indicates that some or all of the base stations &, b, c use the same time-frequency resources to serve the mobile terminal.

In the present invention, the space division multiple access and interference cancellation techniques used to serve multiple mobile terminals or to serve one or more mobile terminals while simultaneously eliminating interference to one or more mobile terminals have a certain relationship with the number of transmitting antennas of the base station, that is, The number of mobile terminals (including the mobile terminals it serves and the mobile terminals that need to perform interference cancellation) that a base station can associate on one time-frequency resource is limited by the number of transmit antennas, Factors such as antenna spacing. Therefore, according to a preferred embodiment of the present invention, when scheduling, the scheduling device D refers to the remaining space division capability of each base station on each time-frequency resource, for example, the spatial separation capability of a base station is at most ² , and it is already T ² F2 service. Two mobile terminals. At this time, the scheduling device D will not separately require the base station to perform a new mobile terminal or a new mobile terminal on T2F2 last month. . Certainly, the scheduling device D may not consider the remaining air separation capability of each base station when performing scheduling, and after receiving the indication information of the scheduling device D, the base station determines whether to obey the scheduling according to its corresponding residual air separation capability. . - when the RSSI indicates that the difference between the optimal signal quality and the suboptimal signal quality is greater than a second predetermined threshold and the mobile terminal is located within the coordinated area, indicating a base station corresponding to the optimal one signal quality for the mobile terminal service. It is assumed that the mobile terminals 1, 2 satisfy the above conditions and their respective serving base stations are base stations _c , b.

Those skilled in the art can determine appropriate values for each predetermined threshold value described in the present invention without any inventive effort, and no further details are provided herein.

According to an embodiment of the present invention, the scheduling device D determines the time-frequency resources used for transmitting the downlink signals to the mobile terminal for the respective serving base stations while determining the serving base stations for the respective mobile terminals. It is assumed that the time-frequency resources used by the scheduling device D for transmitting the downlink signals to the corresponding mobile terminals in FIG. 1 are the same and are T1F1, when the base stations &, b jointly send downlink signals to the mobile terminal 0. At the same time, the base stations c and b also transmit downlink signals to the mobile terminals 1, 2, respectively, using T1F1. Therefore, it is necessary to consider the interference therebetween.

According to a specific embodiment of the present invention, the scheduling device D can instruct the base station c to suppress the interference to the mobile terminal 0 when transmitting a signal to the mobile terminal 1, and instruct the base stations a, b to suppress the transmission of the signal to the mobile terminal 0, thus The interference of the mobile terminal 1.

According to a preferred embodiment of the present invention, the scheduling device D instructs the base station c to suppress the movement when transmitting a signal to the mobile terminal 1 only when the signal quality between the base station c and the mobile terminal 0 is higher than the third predetermined threshold. Similarly, if the signal quality between the base stations a, b and the mobile terminal 1 is not higher than the third predetermined threshold, the scheduling device D will not instruct the base stations a, b to eliminate the thousand to the mobile terminal 1. Disturb.

So far, the mobile terminals associated with each of the cooperative base stations shown in the figure are all determined as follows:

The base station a: serves the mobile terminal 0 with the same time-frequency resource such as T1F1 with the base station b, and eliminates interference to the mobile terminal 1;

Base station b: with the base station a serving the mobile terminal 0 with T1F1, and serving the mobile terminal 2 with T1F1;

Base station c: Serves mobile terminal 1 with T1F1.

Then, the scheduling device D informs the respective bases of the above information and the corresponding time-frequency resources. Station, and control to push the service data to be sent to each mobile terminal to the corresponding service base station.

Each base station will transmit a downlink signal to the mobile terminal that should be served according to the indication of the scheduling device D, and at the same time, cancel the interference to some mobile terminals according to the indication of the scheduling device D. The specific descriptions for each base station are as follows:

Base station a

As mentioned above, in addition to the need to serve the mobile terminal 0, the base station a has a strong signal quality with the mobile terminal 1 but does not constitute a service relationship (for the terminal 1, the signal quality of the base station c exceeds A second predetermined threshold of the quality of the base station a) needs to eliminate interference with the mobile terminal 1. To this end, base station a needs to precode the service data addressed to mobile terminal 0. The information required by the base station a to generate the precoding matrix includes only channel state information between the base station a and the mobile terminal 0 (eg, the instantaneous channel response matrix H_aO) according to the information of the mobile terminal associated with the scheduling device indicated by the scheduling device. And channel state information (e.g., instantaneous channel response matrix H-al) between base station a and mobile terminal 1. After the precoding matrix is generated based on the prior art, the precoding of the service data to be sent to the mobile terminal 0 is performed by using the precoding matrix, that is, the precoded downlink signal to be sent to the mobile terminal 0 is obtained, and the specific User MIMO or beamforming forms a null in the direction of the mobile terminal 1, thereby ensuring that the interference to the mobile terminal 1 is reduced while serving the mobile terminal 0.

The time-frequency resource T1F1 used by the base station a to transmit the downlink signal to the mobile terminal 0 can be coordinated and allocated by the scheduling device D, and is the same as the time-frequency resource used by the base station b to serve the mobile terminal 0. The cooperative working modes of base stations a and b include but are not limited to: space time coding, spatial multiplexing, space diversity, and the like. Taking spatial multiplexing as an example, the following is explained:

The scheduling device D can control the channel-coded service data {S(0), S(1), S(2), ..., S(2n), ... } to be sent to the mobile terminal 0. Two paths are sent to base station a and base station b accordingly, wherein the signal flows sent to base station a are: {S(0), S(2), S(4), ..., S(2n),. ..} ; The signal stream sent to base station b is {S(l), S(3), S(5), S(2n-1),...}. Thereafter, the base station a precodes {S(0), S(l), S(2), ..., S(2n), ... } using the above precoding matrix.

The scheduling device D can also directly send the complete service data to the two serving base stations of the mobile terminal 0, and the two service base stations respectively perform channel coding to obtain {S(0), S(l), S(2), ..., S(2n), ·..} Thereafter, the base station a and the base station b determine the data streams respectively transmitted to the mobile terminal 0 based on pre-configuration or scheduling.

As for the case where the two serving base stations use the space-time coding to jointly send the downlink signal to the mobile terminal 0, the scheduling device D can complete the space-time coding on the channel-coded service data, and the two signals obtained by the coding are included. All the way to the base station a, the other way to the base station b. The base station a will pre-code the obtained space-time coded signal; or, the scheduling device D sends the complete service data to the base station a and the base station b, and respectively performs channel coding to obtain {S(0), S(1) ), S(2), ..., S(2n), ... } and complete space time coding, and select one way pre-coded to terminal 0 based on pre-configuration or scheduling.

As mentioned above, the signal quality related information obtained by each base station has various forms. When it is RSSI or CQI, the base station needs to obtain channel state information such as the instantaneous channel response matrix H before performing precoding; When it is channel state information, the base station can directly use the previously obtained channel state information for the generation of the precoding matrix when performing precoding. During the scheduling interval between one scheduling and the next scheduling, the base station may also obtain channel state information multiple times to update the respective precoding matrices in real time.

It is not difficult to see that after the introduction of the present invention, when performing precoding matrix calculation, each base station does not need to interact with other base stations to calculate channel state information of the precoding matrix, but only needs to obtain the channel state information acquired by itself. Signal precoding with better interference suppression effect can be completed, which avoids a large occupation of Backhaul network resources.

Base station b

The base station b needs to use the T1F1 to serve the mobile terminal 0 and the mobile terminal 2 without performing interference cancellation on any mobile terminal.

Therefore, the base station b needs to obtain the channel state information between the base station b and the mobile terminal 0, 2, including: between the base station b and the mobile terminal 0, such as the instantaneous channel response matrix H-b0, and between the base station b and the mobile terminal 2 The instantaneous channel response matrix H__b2, and based on the prior art, generates a precoding matrix for precoding the traffic data to be sent to the mobile terminals 0, 2. The precoding matrix can ensure that signals to be sent to one mobile terminal are well received by the mobile terminal without causing little interference or interference to another mobile terminal. After precoding the service data by using the generated precoding matrix, it is sent to the mobile terminal. The precoded downlink signal of terminals 0, 2. Those skilled in the art understand that it can be implemented based on multi-user MIMO or beamforming technology, and details are not described herein.

As previously, the base station b cooperates with the base station a to jointly serve the mobile terminal 0 using any single-user MIMO technology, and can use any single-user MIMO technology for serving the mobile terminal 2, for example, space-time coding, spatial multiplexing Use, spatial diversity, etc. No longer.

Base station c

The base station c needs to transmit the downlink signal only to the mobile terminal 1 using T1F1. No interference cancellation is required for any mobile terminal.

The base station c can use any kind of single-user MIMO technology for serving mobile terminals 1, such as space-time coding, spatial multiplexing, spatial diversity, and the like. No longer.

According to the present invention, cooperation between a plurality of cooperation areas can also be performed by scheduling information interaction between devices.

The present invention has been described in detail above from the perspective of the system. Hereinafter, the flowchart and the block diagram of the device will be described from the perspective of the scheduling device and the base station, respectively, with reference to FIG.

2 is a diagram of a method for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations within a coordination area under the jurisdiction of the scheduling device in a scheduling device of a wireless communication network, in accordance with an embodiment of the present invention. flow chart.

First, in step S10, the scheduling device D acquires signal quality related information (identified by the feature information of the corresponding mobile terminal) between the plurality of cooperative base stations a, b, c and their respective nearby mobile terminals, in this example, scheduling The device is a network device independent of each base station, and receives signal quality related information such as RSSI between each base station reported by the base stations a, b, c and the mobile terminals 0, 1, 2 via the Backhaul network. In a variant, assuming that the function of the scheduling device is integrated at the base station a, the implementation process of the step S10 includes: the base station a itself obtains the RSSI between the mobile terminal a, b, e; the base station a Receive RSSI reported by base stations b, c. In the following, the case where the base station and the scheduling device shown in FIG. 1 are independent of each other will be described as an example.

After acquiring the signal quality related information, the method proceeds to step S11, where the scheduling device D compares the cooperative base stations and the mobile terminals according to the RSSI reported by each base station. MIMO communication is scheduled as follows:

- for mobile terminal 0, since the RSSI indicates the signal quality between it and the base stations _a , b, c (abbreviated as S _x , where X is the corresponding reference number of the base station), the relationship is S _a >S _b >S _c , and S _a - S _b <first predetermined threshold (TH1 ), and Sa _a - S _C >TH1 , therefore, the scheduling device D instructs the base stations a, b to use the same as the serving base station of the mobile terminal 0 in step S11 The time-frequency resource T1F1 sends a downlink signal thereto. Considering that a mobile terminal capable of simultaneous service by several base stations depends on the receiving capability of the mobile terminal and the MIMO mode adopted for the mobile terminal, therefore, when a mobile terminal and the base station, b, c three signals When the quality is relatively close, the scheduling device D determines to be served by one or more of the three cooperative base stations according to its receiving capability and the corresponding MIMO mode. In this example, it is assumed without loss of generality that a mobile terminal is served by at most two base stations at the same time.

- for mobile terminals 1, 2, scheduling device D in step Sir, since their respective associated RSSI indicates that the signal quality between them and one of the base stations is good and exceeds the signal quality between the other base stations by at least a second predetermined threshold The base station c indicating the optimum signal quality with the mobile terminal 1 serves as the serving base station of the mobile terminal 1 to transmit a downlink signal thereto; and indicates the base station b having the best signal shield amount with the mobile terminal 2 as the service of the mobile terminal 2. The base station sends a downlink signal to it.

It is assumed that the scheduling device D instructs the base stations a, b, c to use the same time-frequency resource T1F1 to respectively transmit downlink signals to the mobile terminals it serves.

Thus, in step S12, the scheduling device D will be able to detect that the base stations a, b, c use the same time-frequency resources to transmit downlink signals to the mobile terminals they serve. Thereafter, the scheduling device D can only indicate the coordinated base stations under its control to eliminate interference caused by time-frequency resource multiplexing.

However, there is blindness in this way. For example, even if the base station a transmits a signal to the mobile terminal 0 it serves with maximum power without performing interference cancellation on the mobile terminal 2, since the distance between the base station a and the mobile terminal 2 is very far When the signal sent by the base station a arrives at the mobile terminal 2, its signal quality is poor, and the interference caused to the mobile terminal 2 is small. If the base station a is instructed to send a downlink signal to the mobile terminal 0 using T1F1 at this time. At the same time, the interference to the mobile terminal 2 is eliminated, and the space division capability of the base station on T1F1 will be consumed unnecessarily.

Based on this, after the scheduling device D detects that different base stations use the same time-frequency resource to send downlink signals to different mobile terminals in step 13, the mobile terminal 0 is taken as an example, and the operation in step S13 is preferably performed, that is, by signal quality. Correlation information to determine whether the signal quality between the base station c and the mobile terminal 0 is higher than a third predetermined threshold, and only proceeds to step S when the signal quality between the base station c and the mobile terminal 0 is higher than the third predetermined threshold. The base station c is instructed in 14 to suppress interference with the mobile terminal 0 when transmitting a signal to the mobile terminal 1. Similarly, for the mobile terminal 1, the scheduling device D is in step S14 only when the result of the determination in step S13 indicates that the signal quality between at least one of the base stations 3, b and the mobile terminal is higher than a third predetermined threshold. The medium base station is instructed to cancel the interference to the mobile terminal 1. For the mobile terminal 2, whether the base station a, c needs to perform interference cancellation analysis and so on.

Preferably, the scheduling device D also considers the space division capability of each base station on a certain time-frequency resource when scheduling. For example, it is assumed that the space division capability of the base station a is 2 (indicating that the mobile terminal capable of serving on one time-frequency resource and the total number of mobile terminals performing interference cancellation simultaneously do not exceed 2), and then, when determining that the base station a uses T1F1 as the mobile terminal After 0 service, the remaining space division capability of base station a on T1F1 becomes 1; and when it is further determined that base station a needs to perform interference cancellation on mobile terminal 1 on T1F1, the remaining space division capability of base station a on T1F1 is changed. If it is 0, it will no longer be able to serve more mobile terminals, or perform interference cancellation for more mobile terminals.

3 is a flow diagram of a method for MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network, in accordance with an embodiment of the present invention. Still combined with Figure 1, the description is as follows.

First, in step S20, each of the base stations in Fig. 1 obtains signal quality related information between its respective mobile terminals in its vicinity.

For the case where the base station and the scheduling device shown in FIG. 1 are independent of each other, the process of obtaining the indication information related to the base station in the step 21 is specifically implemented by the following sub-steps not shown in the figure:

S211: signal quality between the base station to be obtained and each mobile terminal in the vicinity thereof The related information is reported to the scheduling device to which the base station belongs;

S212: Receive indication information related to the base station from the scheduling device, where the indication information is used to indicate one or more mobile terminals associated with the base station.

According to a variant of the example, in the sub-step S211, each base station filters the signal quality related information obtained between the mobile terminals and the mobile terminal, and specifically selects that the mobile terminal is about to perform the handover. Signal quality related information and signal quality related information indicating that the signal quality exceeds a fourth predetermined threshold for reporting to scheduling device 0. Assuming that the signal quality between the base station a and the mobile terminal 2 is extremely poor (below the fourth predetermined threshold) and the mobile terminal 2 does not need to perform handover, the base station a may choose not to report to the scheduling device D that it is associated with the mobile terminal 2. Signal quality between. It is understood by those skilled in the art that, in the subsequent scheduling process, when the scheduling device D selects a serving base station for a certain mobile terminal or determines a base station that performs interference cancellation, it may report only the signal quality related information with the mobile terminal. The above selection is made in each base station.

After obtaining the indication information from the scheduling device D in step S21, each base station performs a corresponding operation based on the indication information. Take the base stations a, b, and c as examples for brief description. Please refer to the related introduction above.

In the simplest case, as shown in step S22, on a time-frequency resource, a base station has only one mobile terminal associated with it (only one mobile terminal needs to be served), and no interference cancellation is required for any mobile terminal. . This situation corresponds to the base station c shown in Fig. 1. Therefore, the base station c only needs to transmit the downlink signal to the mobile terminal 1 on all the transmit antennas on the time-frequency resource T1F1 based on the existing single-user MIMO technology. The single-user MIMO mode available to the base station c includes space-time coding or spatial multiplexing or spatial diversity.

For the case of base station b, it uses time-frequency resource T1F1 to simultaneously serve two mobile terminals 0, 2. Therefore, in step S22", the base station b needs to perform precoding processing on the service data to be sent to the two mobile terminals, and to generate the precoding matrix, the base station b only needs to know between it and the mobile terminals 0, 2. For example, the instantaneous channel response matrices H_b0 and HJD2. The manner of transmitting downlink signals to the mobile terminals 0, 2 on the same time-frequency resource includes multi-user MIMO and beamforming.

For the case of base station a, it needs to use the time-frequency resource T1F1 to serve the mobile terminal. 0, it is also necessary to eliminate interference to the mobile terminal 1 on the time-frequency resource T1F1. Therefore, in step S22, the base station a only needs to know the instantaneous channel response matrices H_a0 and H_al between it and the mobile terminals 0, 1. Eliminating interference to the mobile terminal 1 while serving the mobile terminal 0 can be realized by generating a precoding matrix using multi-user MIM 0 and beamforming or the like.

For the base stations &, b, since the channel state information needs to be known for generating the precoding matrix, when the information obtained in the previous step S20 is RSSI or CQI instead of channel state information, to generate a precoding matrix, the base stations a, b The corresponding channel indicated by the scheduling device D needs to be detected (e.g., channel estimation, etc.). When the information obtained in the previous step S20 is the channel state information, the base stations a, b can directly use the channel state information associated with the corresponding mobile terminal in the obtained channel state information for the generation of the precoding matrix. During the scheduling interval between one scheduling and the next scheduling, the base station may also obtain channel state information multiple times to update its respective precoding matrix in real time.

According to a specific embodiment of the present invention, it is assumed that the cooperative base station subordinate to the scheduling device D further includes a base station e (corresponding to S22 "' in FIG. 3) not shown in the figure, and the signal quality between the mobile station and each mobile terminal is Very poor, then, because the base station e does not report the signal quality related information with any mobile terminal; or because the base station e reports the signal quality related information, the scheduling device D finds that the base station e is not suitable as an A serving base station of the mobile terminal, the scheduling device D will not instruct the base station e to serve a certain mobile terminal (naturally, it will not be instructed to perform interference cancellation). In addition, it may also be because the base station e has no remaining air separation capability on T1F1. It is not instructed to serve other mobile terminals on T1F1 or perform interference cancellation on a certain terminal.

A person skilled in the art can understand that the mutual order of the steps in the various flowcharts in the present application is only corresponding to the specific embodiments of the present invention, and does not constitute a limitation on the scope of the present invention. .

4 is a scheduling for scheduling MIMO communication between a mobile terminal and a plurality of cooperative base stations within a cooperation area under the jurisdiction of the scheduling device in a scheduling device of a wireless communication network according to an embodiment of the present invention. Device block diagram.

The scheduling device 10 shown includes: a signal quality obtaining device 100, a first indicating device 101, a second indicating device 102, a detecting device 103, a third indicating device 104, and a signal The transmission control device 105, wherein the third indication device 104 further includes an interference cancellation determination device 1040 and an interference cancellation indication device 1041.

First, the signal quality obtaining apparatus 100 in the scheduling device D acquires signal quality related information between the plurality of cooperative base stations a, b, c and mobile terminals in the vicinity thereof. In this example, the scheduling device D is mutually connected with each base station. A separate network device that receives signal quality related information such as RSSI between each base station reported by the base stations &, b, c and the mobile terminals 0, 1, 2 via the Backhaul network. In a variant, assuming that the function of the scheduling device is integrated in the base station a, for which the function of the signal quality obtaining device 100 comprises: obtaining the RSSI between the base station a itself and the mobile terminals a, b, c; RSSI reported by base stations b, c. In the following, the case where the base station and the scheduling device shown in FIG. 1 are independent of each other will be described as an example.

The signal quality obtaining means 100 provides the signal quality related information obtained by the signal quality obtaining means 100 to the respective pointing means, and the respective indicating means respectively instruct the respective base stations based on the corresponding information. The mobile terminals shown in Figure 1 are discussed as follows:

- For mobile terminal 0, since the RSSI indicates the signal quality between it and the base stations a, b, c (abbreviated as SX, where X is the corresponding reference number of the base station), the relationship is Sa>Sb>Sc, and Sa-Sb< The first predetermined threshold (TH1), and Sa-S>TH1, therefore, the first indication means 101 instructs the base stations a, b to transmit downlink signals to the serving base station of the mobile terminal 0 using the same time-frequency resource T1F1. A person skilled in the art understands that the signal quality between a mobile terminal and the base stations &, b, c may be relatively similar, then the first pointing device 101 will indicate that the three base stations or any two of the base stations are used. The same time-frequency resource T1F1 sends a downlink signal to the mobile terminal. Considering that a mobile terminal capable of being simultaneously served by several base stations depends on the receiving capabilities of the mobile terminal (eg, the number of receiving antennas, etc.) and the MIMO mode adopted for the mobile terminal, therefore, when a mobile terminal and the base station a, When the signal quality between b and c is relatively similar, the scheduling device D determines to serve one or more of the three cooperative base stations according to its receiving capability and the corresponding MIMO mode. In this example, it is assumed without loss of generality that a mobile terminal is served by at most two base stations at the same time.

- For mobile terminals 1, 2, due to their respective associated RSSI indications with a base The signal quality between the stations is best and exceeds the signal quality between the other base stations by at least a second predetermined threshold, and the second indication means 102 will indicate the base station c indicating the optimal signal quality with the mobile terminal 1 as the mobile terminal 1. The serving base station transmits a downlink signal thereto, and indicates that the base station b having the best signal quality with the mobile terminal 2 serves as the serving base station of the mobile terminal 2 to transmit a downlink signal thereto.

Suppose first scheduling apparatus D, the second base station indicating means indicates frequency resource T1F1 _¾, b, c when using the same downlink signals are transmitted to the mobile terminal to its service.

Thus, the detecting means 103 in the scheduling device D will be able to detect that the base stations a, b, c use the same time-frequency resources to transmit downlink signals to the mobile terminals they serve. Thereafter, the third indication device 104 can only instruct each of the cooperative base stations to eliminate interference caused by multiplexing of time-frequency resources based on this.

However, there is blindness in this way. For example, even if the base station a transmits a signal to the mobile terminal 0 it serves with maximum power without performing interference cancellation on the mobile terminal 2, since the distance between the base station a and the mobile terminal 2 is very far When the signal sent by the base station a arrives at the mobile terminal 2, its signal quality is already poor, and the interference to the mobile terminal 2 is small. If the base station a is instructed to cancel the interference to the mobile terminal 2 while transmitting the downlink signal to the mobile terminal 0 using T1F1, the space division capability of the base station on T1F1 will be unnecessarily consumed.

Based on this, taking the mobile terminal 0 as an example, preferably, the interference cancellation determining apparatus 1040 in the third indication device 104 determines whether the signal quality between the base station c and the mobile terminal 0 is higher than the third predetermined by the signal quality related information. The threshold, only when the signal quality between the base station c and the mobile terminal 0 is higher than the third predetermined threshold, notifying the interference cancellation indicating device 1041 to instruct the base station c to suppress the mobile terminal 0 while transmitting a signal to the mobile terminal 1. Interference. Similarly, for the mobile terminal 1, only when the determination result obtained by the interference cancellation determining means 1040 indicates that the signal quality between at least one of the base stations a, b and the mobile terminal 1 is higher than a third predetermined threshold, the interference cancellation indicating means 1041 The corresponding base station is instructed to eliminate interference with the mobile terminal 1. For the mobile terminal 2, whether the base station a, c needs to perform interference cancellation analysis and so on.

Preferably, the scheduling device D also considers each base station in a certain time-frequency resource when scheduling. The ability to divide the air. For example, it is assumed that the space division capability of the base station a is 2 (indicating that the mobile terminal capable of serving on one time-frequency resource and the total number of mobile terminals performing interference cancellation simultaneously do not exceed 2), and then, when determining that the base station a uses T1F1 as the mobile terminal After 0 service, the remaining space division capability of base station a on T1F1 becomes 1; and when it is further determined that base station a needs to perform interference cancellation on mobile terminal 1 on T1F1, the remaining space division capability of base station a on T1F1 becomes 0, will no longer be able to serve more mobile terminals, or perform interference cancellation for more mobile terminals. The consideration of the space division capability can be realized by a space division capability monitoring device not shown in the figure, which acts on each pointing device based on the remaining space division capabilities of the respective base stations.

The signal transmission control means 105 is mainly for controlling the distribution of service data to be transmitted to a certain mobile terminal to each of the serving base stations determined for the mobile terminal based on the indication information obtained by the respective indication means.

5 is a block diagram of a communication device for performing MIMO communication with a mobile terminal based on scheduling in a base station of a wireless communication network, in accordance with an embodiment of the present invention. Still described below in conjunction with Figure 1.

The communication device 20 is configured in each base station shown in FIG. 1, and specifically includes: a signal quality obtaining device 200, an indication information acquiring device 201, a matrix generating device 202, a precoding device 203, a receiving device 204, and a notification device 205, wherein The indication information acquiring apparatus 201 includes: a signal quality reporting apparatus 2010 and an indication information receiving apparatus 2011. More specifically, the signal quality reporting apparatus 2010 includes a determining apparatus 20100 and a controlled reporting apparatus 20101.

First, the signal quality obtaining means 200 in each base station in Fig. 1 obtains signal quality related information between respective base stations and respective mobile terminals in the vicinity thereof.

For the case where the base station and the scheduling device shown in FIG. 1 are independent of each other, the working modes of the sub-devices of the indication information acquiring device 201 are as follows:

The signal quality reporting device 2010 reports the signal quality related information between the base station obtained by the signal quality obtaining device 200 and each mobile terminal in the vicinity thereof to the scheduling device to which the base station belongs;

Instructing information receiving device 2011 to receive from the scheduling device related to the base station Instructions.

According to a variant of the example, the determining device 20100 in the signal quality reporting device 2010 selects the obtained signal shield related information between the base station and each mobile terminal, and specifically selects the mobile terminal. The signal shield amount related information to be handed over and the signal quality related information indicating that the signal quality exceeds the fourth predetermined threshold are reported to the dispatching device D by the controlled reporting device 20101. Assuming that the signal quality between the base station a and the mobile terminal 2 is extremely poor (below the fourth predetermined threshold) and the mobile terminal 2 does not need to perform handover, the determining device 20100 in the base station a may select not to schedule. The device D reports the signal quality between it and the mobile terminal 2. It is understood by those skilled in the art that during the subsequent scheduling process, the scheduling device D may only select a serving base station for a certain mobile terminal or determine a base station performing interference cancellation. The above selection is made in each of the base stations reporting the signal quality related information with the mobile terminal.

The base station will thereafter perform a corresponding operation based on the indication information acquired by the indication information acquisition means 201. Take the base stations a, b, and c as examples for brief description. Please refer to the related introduction in the above.

The simplest case is base station c, which only needs to transmit downlink signals to mobile terminal 1 on all time-frequency resources T1F1 based on existing single-user MIMO technology. The single-user MIMO mode available to the base station c includes space-time coding or spatial multiplexing or spatial diversity. The processing device for single-user MIMO is not shown for the sake of simplicity in the figure.

The base station b uses the time-frequency resource T1F1 to simultaneously serve two mobile terminals 0, 2. Therefore, the precoding apparatus 203 at the base station b needs to perform precoding processing on the service data to be sent to the two mobile terminals sent by the scheduling device D, and to generate a precoding matrix, the matrix generating device 202 only needs to know the base station. b as the instantaneous channel response matrices H-b0 and H-b2 between the mobile terminals 0, 2. The manner in which the downlink signals are transmitted to the mobile terminals 0 and 2 on the same time-frequency resource includes multi-user MIMO and beamforming to generate a precoding matrix.

For the base station a, it needs to use the time-frequency resource T1F1 to serve the mobile terminal 0, and it is also necessary to eliminate the interference to the mobile terminal 1 on the time-frequency resource T1F1. Therefore, the matrix generating means 202 at the base station a only needs to know the instantaneous channel between the base station a and the mobile terminal 0, 1. Response matrices H_a0 and H-al. The manner of eliminating the interference to the mobile terminal 1 while serving the mobile terminal 0 includes multi-user MIMO and beamforming, and the like.

For the base stations 3 and b, since the channel state information needs to be known for generating the precoding matrix, when the information obtained by the signal quality obtaining apparatus 200 is the RSSI or CQI instead of the channel state information, in order to generate the precoding matrix, the channel needs to be generated. The quality obtaining means detects the corresponding channel (e.g., channel estimation) according to the indication information to obtain channel state information. When the information obtained by the signal quality obtaining apparatus 200 is the channel state information, the precoding apparatus 203 in the base stations a, b can directly use the part of the obtained channel state information related to the corresponding mobile terminal for the precoding matrix. Generation. During the period from one scheduling to the next scheduling, a base station can obtain channel state information multiple times to update its own precoding matrix.

According to a specific embodiment of the present invention, the base station a is a scheduling device, and then the receiving device 204 in the communication device 20 receives and summarizes the signal quality related information between the respective base stations and the nearby mobile terminals from other base stations. And the notification means 205 distributes the indication information obtained by the indication information acquisition means 201 locally to each of the other base stations.

When the scheduling device does not have the space division capability monitoring device for monitoring the remaining air separation capability of each base station mentioned above, the communication device 20 at each base station should be configured with a device having similar functions to monitor its own remaining The air separation capability, thereby determining whether to obey the corresponding scheduling instructions of the scheduling device.

6 is a system diagram of multi-base station cooperative MIMO and its scheduling for low information interaction, in accordance with an embodiment of the present invention. The M cooperative base stations that belong to the same scheduling device D are connected to the scheduling device D through the Backhaul network.

BSi (i = l, ..., M) has a precoding matrix generator (i.e., the matrix generating device described above) for calculating BSi's own precoding matrix Wi to implement SDMA and interference cancellation. The precoder is the precoding device described above.

The workflow of the system shown in Figure 6 is briefly described below. Please refer to the corresponding content in the above:

1) Each base station reports the base station and mobile to the scheduling device D via the Backhaul network Signal quality related information between terminals (such as RSSI or CQI);

2) The scheduling device D determines the service relationship between each coordinated base station and the mobile terminal, and sends the indication information of the scheduling decision to the corresponding cooperative base station. Controlled by scheduling device D, the resulting scheduling decision, the user data distributor is able to send the user data stream accordingly to the serving base station of the corresponding mobile terminal. In the figure, di indicates the user data stream to be sent to BSi;

3) Based on the indication information of the scheduling decision, the BSi detects the CSI between itself and the mobile terminal associated therewith, such as Hi, and the precoding matrix generating means on the BSi generates the precoding matrix Wi according to the CSI, thereby implementing, for example, beamforming. Or multi-user MIMO.

It should be understood that the Backhaul network shown in FIG. 6 only exemplarily illustrates the connection relationship between each base station and each base station and the scheduling device. In actual networking, the network may adopt, for example, a star type, a bus type, and others. Various network structures.

The embodiments of the present invention have been described above, but the present invention is not limited to the specific systems, equipment, and specific protocols, and various modifications and changes can be made by those skilled in the art within the scope of the appended claims.

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Signal quality acquisition device second indication device detection device

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Claims

Claim

A method for cooperatively transmitting signals to one or more mobile stations on a same time-frequency resource as another one or more base stations in a base station of a wireless communication network, comprising the steps of:

a. acquiring long-term channel information of the downlink wireless communication link of the base station to the one or more mobile stations;

b. pre-processing one or more signals sent by the base station to the one or more mobile stations based on the long-term channel information and a predetermined rule to obtain a pre-processed signal;

c transmitting the pre-processed signal to the one or more mobile stations on time-frequency resources agreed with the other one or more base stations.

2. The method according to claim 1, wherein the step a includes the following steps:

Obtaining a plurality of estimated values of a channel response matrix of the base station to the one or more mobile stations;

Determining the long-term channel information according to a plurality of estimated values of the channel response matrix

3. The method according to claim 2, wherein the step al further comprises the following steps:

- receiving a plurality of estimated values of the channel responses of the respective wireless communication links of the respective base stations to the respective mobile stations transmitted by the respective mobile stations.

4. The method according to claim 2, wherein the step al further comprises the following steps:

Receiving an uplink signal respectively sent from the respective mobile stations;

Al2. Calculating a plurality of estimated values of the channel response matrix of the base station to the respective mobile stations according to the uplink signals.

The method according to claim 4, wherein the uplink signal comprises an uplink sounding signal.

The method according to any one of claims 1 to 5, wherein the preprocessing comprises a precoding process, and the step b comprises the following steps:

Bl. determining, based on the long-term channel information and a predetermined rule, a precoding coefficient of one or more signals transmitted to the one or more mobile stations on one or more transmit antennas of the base station;

B2. performing precoding processing on the one or more signals sent to the one or more mobile stations according to the precoding coefficient, to obtain the precoded processed message, the step c further includes The following steps:

- transmitting the precoded signal to the one or more mobile stations on one or more antennas on time-frequency resources agreed with the other one or more base stations.

The method according to claim 6, wherein the long-term channel information comprises a covariance matrix of a plurality of estimated values of a channel response matrix of the base station to the one or more mobile stations, the predetermined The rules include precoding rules based on covariance matrices.

8. The method according to claim 7, wherein the covariance matrix based precoding rules comprise precoding rules based on singular value decomposition of the covariance matrix.

The method according to any one of claims 1 to 8, wherein the plurality of estimated values of the channel response matrix comprise channel responses obtained at a plurality of time points and/or a plurality of frequency points The estimated value of the matrix.

The method according to any one of claims 1 to 5, characterized in that the preprocessing comprises a closed loop space time coding process.

11. The method of claim 1, wherein the channel long-term information comprises a signal departure angle or an angle of arrival, the predetermined rule comprising a beamforming rule based on a signal exit angle or an angle of arrival.

12. A cooperative transmission apparatus for cooperatively transmitting signals to one or more mobile stations on a same time-frequency resource as another one or more base stations in a base station of a wireless communication network, comprising: And an acquiring device, configured to acquire long-term channel information of a downlink wireless communication link of the base station to the one or more mobile stations;

a pre-processing device, configured to perform pre-processing on one or more signals sent by the base station to the one or more mobile stations based on the long-term channel information and a predetermined rule to obtain a pre-processed signal;

And transmitting means, configured to send the pre-processed signal to the one or more mobile stations on a time-frequency resource agreed with the other one or more base stations.

The cooperative transmission device according to claim 12, wherein the obtaining means comprises:

Channel response obtaining means, configured to acquire a plurality of estimated values of a channel response matrix of the base station to the one or more mobile stations;

The first determining means is configured to determine the long-term channel information according to the plurality of estimated values of the channel response matrix.

The cooperative transmission device according to claim 13, wherein the channel response acquiring device is further configured to:

The device according to claim 13, wherein the channel response acquiring device further comprises:

The receiving device is configured to receive uplink signals respectively sent by the mobile stations, and the calculating device is configured to separately calculate, according to the uplink signals, multiple estimated values of a channel response matrix of the base station to each mobile station.

16. The cooperative transmission apparatus according to claim 15, wherein the uplink signal comprises an uplink sounding signal.

The cooperative transmission device according to any one of claims 12 to 16, wherein the preprocessing comprises a precoding process, and the preprocessing device comprises:

a second determining means, configured to determine, according to the long-term channel information and a predetermined rule, a precoding coefficient of one or more signals sent to the one or more mobile stations on one or more transmitting antennas of the base station ; a precoding processing apparatus, configured to perform precoding processing on the one or more signals sent to the one or more mobile stations according to the precoding coefficient, to obtain the precoded processed signal;

The transmitting device is further configured to:

The cooperative transmission device according to claim 17, wherein the long-term channel information comprises a covariance matrix of a plurality of estimated values of a channel response matrix of the base station to the one or more mobile stations, where The predetermined rules include precoding rules based on a covariance matrix.

19. The cooperative transmission apparatus according to claim 18, wherein the covariance matrix based precoding rule comprises a precoding rule based on singular value decomposition of the covariance matrix.

The cooperative transmission device according to any one of claims 12 to 19, wherein the plurality of estimated values of the channel response matrix are obtained at a plurality of time points and/or a plurality of frequency points Estimated value of the channel response matrix.

The cooperative transmission apparatus according to any one of claims 12 to 16, wherein the preprocessing comprises closed loop space time coding processing.

22. The cooperative transmission apparatus according to claim 12, wherein the channel long time information comprises a signal departure angle or an arrival angle, and the predetermined rule comprises a beamforming rule based on a signal departure angle or an angle of arrival.