CN102025665A

CN102025665A - Transmission method and equipment

Info

Publication number: CN102025665A
Application number: CN2009101960572A
Authority: CN
Inventors: 吴克颖
Original assignee: Alcatel Lucent Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2009-09-18
Filing date: 2009-09-18
Publication date: 2011-04-20
Anticipated expiration: 2029-09-18
Also published as: CN102025665B

Abstract

The invention discloses a transmission method and transmission equipment. The method is applied to an X channel consisting of a plurality of receivers and a plurality of transmitters and comprises: generating a pre-coding matrix for each of the plurality of receivers; pre-coding signal vectors to be transmitted to the plurality of receivers by using the pre-coding matrixes; and transmitting the pre-coded signal vectors to the plurality of receivers. According to the technical scheme provided by the embodiment of the invention, an X channel transmission scheme which is easy to implement and can provide high degree of freedom is provided.

Description

Transmission method and equipment thereof

Technical Field

Embodiments of the present invention relate generally to wireless communication technologies, and in particular, to a transmission method and an apparatus thereof.

Background

With the rapidly growing demand for higher wireless data rates and better wireless quality of service, inter-cell interference (ICI) has become an increasingly serious problem for cellular systems. In recent years much attention has been drawn to the study of the so-called X channel, which provides one possible way to solve the ICI problem. The X channel is a wireless system with multiple transmitters and multiple receivers. Each transmitter sends an independent message to each receiver and there is no coordination between transmitters or receivers, i.e. the transmitter and receiver do not share data information. The X channel has much lower requirements on the transmission bandwidth and transmission delay of the backbone network than a fully coordinated scheme where the transmitter and receiver share full data and channel information. The X channel has certain advantages in terms of degree of freedom (DoF) compared to an interfering channel, where each receiver receives messages from only one transmitter.

Due to a good tradeoff between performance and complexity, the X channel becomes a promising solution to the ICI problem. There are two kinds of X-channel implementation techniques, one is cooperative multiple input multiple output (Co-MIMO), and the other is Interference alignment (Interference alignment). Co-MIMO allows multiple Base Stations (BSs) to simultaneously serve different mobile terminals (MSs) in different cells and avoids inter-cell interference using multi-user precoding without degrading resource utilization. Since only local Channel State Information (CSI) is needed at each base station (CSI between the BS and all MSs in the X channel), this technique is simple and easy to implement, but does not achieve the maximum degree of freedom for the X channel. The interference alignment technique can achieve the maximum degree of freedom for the X channel, but requires global CSI (CSI between all BSs and all MSs in the X channel) at each BS, which is an idealized assumption that is difficult to achieve in reality.

Therefore, there is a need for an X-channel transmission scheme that is easy to implement and can provide a high degree of freedom.

Disclosure of Invention

The embodiment of the invention provides a transmission method and equipment thereof.

According to an aspect of the present invention, a transmission method is proposed for use in an X channel composed of a plurality of receivers and a plurality of transmitters. The method comprises the following steps: generating a precoding matrix for each of a plurality of receivers; precoding signal vectors to be transmitted to the plurality of receivers according to a corresponding one of the precoding matrices; the precoded signal vectors are transmitted to a plurality of receivers.

According to another aspect of the present invention, there is also provided a transmission method for use in an X channel composed of a plurality of receivers and a plurality of transmitters, the method including: receiving signal vectors from a plurality of transmitters; filtering signal vectors transmitted by other receivers in the plurality of receivers from the received signal vectors; the filtered signal vectors are decoded to recover the signal vectors precoded in the plurality of transmitters using the precoding matrix, respectively.

According to still another aspect of the present invention, there is also provided a transmitter for use in an X channel composed of a plurality of receivers and a plurality of transmitters, the transmitter comprising: a precoding matrix generating unit for generating a precoding matrix for each of the plurality of receivers; a precoding unit for precoding signal vectors to be transmitted to the plurality of receivers according to a corresponding one of the precoding matrices; and a first transceiving unit configured to transmit the precoded signal vector.

According to still another aspect of the present invention, there is provided a receiver for use in an X channel composed of a plurality of receivers and a plurality of transmitters, the receiver comprising: a second transceiving unit for receiving signal vectors from a plurality of transmitters; the filtering unit is used for filtering the signal vectors which are sent by other receivers in the plurality of receivers in the received signal vectors; and a coding and decoding unit, which is used for decoding the filtered signal vectors so as to respectively recover the useful signal vectors which are precoded by using the precoding matrix in a plurality of transmitters.

According to another aspect of the invention, a communication system is proposed, comprising a plurality of transmitters and receivers as described above.

By the technical scheme, the X channel transmission scheme which is easy to realize and can provide higher degree of freedom is provided.

Drawings

The invention may be better understood by describing in detail embodiments thereof with reference to the accompanying drawings, in which:

fig. 1 is a schematic diagram of a system in which a transmitter is a base station and a receiver is a mobile terminal according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a system in which a receiver is a base station and a transmitter is a mobile terminal according to an embodiment of the present invention;

fig. 3 shows a block diagram of a transmitter in an embodiment of the invention;

FIG. 4 shows a block diagram of a receiver in an embodiment of the invention;

FIG. 5 is a flow chart illustrating X channel transmission in an embodiment of the present invention;

FIG. 6 is a flow chart illustrating precoding matrix generation in an embodiment of the present invention;

FIG. 7 shows a diagram of performance simulation results in an embodiment of the invention.

Detailed Description

In the following detailed description of the preferred embodiments of the present invention, reference is made to the accompanying drawings, in which details and functions that are not necessary for the invention are omitted so as not to obscure the understanding of the present invention.

The embodiment of the present invention provides a system shown in fig. 1 and/or fig. 2, which includes a receiver and a transmitter, where in fig. 1, the transmitter is a base station and the receiver is a mobile terminal, and in fig. 2, the transmitter is a mobile terminal and the receiver is a base station.

An embodiment of the present invention further provides the transmitter shown in fig. 3, including a precoding matrix generating unit 310 for generating a precoding matrix for each of a plurality of receivers; a precoding unit 320 for precoding signal vectors to be transmitted to the plurality of receivers according to a corresponding one of the precoding matrices; a first transceiver unit 330, configured to transmit the precoded signal vector.

The transmitter further comprises an extension unit 350 for transmitting the precoded signal vectors over a plurality of time slots or subcarriers.

The transmitter further comprises a selecting unit 340 for selecting the number of mobile terminals capable of obtaining the maximum degree of freedom according to the respective numbers of antennas of the plurality of transmitters and the plurality of receivers; the precoding matrix generating unit 310 is further configured to generate a precoding matrix for each of the plurality of receivers according to the selected number of mobile terminals.

The transmitter further comprises a first storage unit 360 for storing parameters used by the above units.

The embodiment of the present invention also provides the receiver shown in fig. 4, which includes a second transceiving unit 410 for receiving signal vectors from a plurality of transmitters; a filtering unit 420 for filtering out signal vectors transmitted to other receivers in the plurality of receivers from the received signal vectors, and a coding and decoding unit 430 for decoding the filtered signal vectors to respectively recover the signal vectors precoded by the precoding matrix in the plurality of transmitters.

The receiver may further include a matrix generation unit 450 for generating a filter matrix; if the receiver is a mobile terminal, the second transceiving unit 410 is further configured to send the uplink sounding signal subjected to the conjugate transpose precoding of the filtering matrix to a plurality of transmitters, so that the plurality of transmitters can generate a precoding matrix for each of the plurality of receivers by using the filtering matrix; the filtering unit 420 is further configured to filter out the signal vectors transmitted to other receivers of the plurality of receivers from the received signal vectors by using a filtering matrix.

The receiver may further comprise an extraction unit 440 for combining signal vectors received over a plurality of time slots or subcarriers into one signal vector.

The receiver may further comprise a second storage unit 460 for storing parameters used in the above units.

Although the transmitter and the receiver of the embodiment of the present invention are described above in the form of separate functional modules, each component shown in fig. 3 and 4 may be implemented by a plurality of devices in practical application, and the plurality of components shown may be integrated in a chip or a device in practical application. The transmitter and receiver may also comprise any units and devices for other purposes.

The purpose of the scheme is to decompose the X channel into a plurality of mutually independent channels. In the Downlink (DL) the X channels will be decomposed into mutually independent Multiple Access (MA) channels, while in the Uplink (UL) the X channels will be decomposed into mutually independent Broadcast (BC) channels.

The following describes embodiments of the present invention with reference to fig. 5 and 6, taking a Base Station (BS) as a transmitter and a mobile terminal (MS) as a receiver as an example.

Referring to fig. 5, in step 510, the precoding matrix generation unit 310 of the transmitter i first generates a precoding matrix for each of a plurality of receivers.

Take DL as an example and assume a scenario of two BSs and three MSs. In this scenario, the X channel will be decomposed into 3 MA channels that do not interfere with each other (i.e., are independent of each other). To achieve this, the generated precoding matrix must satisfy the following conditions:

for the receiver 1:

ψ₁H_1，1Q_2，10 and psi₁H_1，1Q_3，1＝0 (1a)

ψ₁H_1，2Q_2，20 and psi₁H_1，2Q_3，2＝0 (1b)

For the receiver 2:

ψ₂H_2，1

Q

_1，10 and psi₂H_2，1Q_3，1＝0 (2a)

ψ₂H_2，2Q_1，20 and psi₂H_2，2Q_3，2＝0 (2b)

For the receiver 3:

ψ₃H_3，1Q_1，10 and psi₃H_3，1Q_2，1＝0 (3a)

ψ₃H_3，2Q_1，20 and psi₃H_3，2Q_2，2＝0 (3b)

Wherein: h_j，i: channel matrix, Q, from transmitter i to receiver j_j，i: for a transmission to receiver j, the precoding matrix used by transmitter i, Ψ_j: receive filter matrix, d, used by receiver j_j，i: number of data streams (DoF) from transmitter i to receiver j. The above constraint means that for a receiver only the signal intended for that receiver can pass its receive filter matrix Ψ_j。

Next, the specific steps of precoding matrix generation will be described with reference to fig. 6.

First, the matrix generation unit 450 of each receiver j randomly generates the reception filter matrix Ψ_jThen the codec unit 430 uses the conjugate transpose of the matrix Ψ_j ^HTo precode a sounding (sounding) signal sequence, and the second transceiver unit 410 transmits the precoded sounding signal. Different receivers transmit respective sounding signals in an orthogonal manner.

Each transmitter i then estimates the sounding signal from the respective receiver

To be butt-jointed withThe precoding matrix of the receiver 1 is taken as an example, and in the embodiment of the invention, the transmitter i is based on Ψ₂H_2，iAnd Ψ₃H_3，iCalculating Q_1，i。

In step 610, according to Ψ₂H_2，iObtain a satisfaction of psi₂H_2，iQ_1，iQ of 0_1，i′。

The specific step may be to perform psi₂H_2，iSVD (singular value decomposition) of (1):

wherein U and

are unitary matrices, and sigma is a diagonal matrix whose diagonal elements are psi₂H_2，iThe singular value of (a). V⁽¹⁾Composed of singular vectors corresponding to non-zero singular values, V⁽⁰⁾Consisting of singular vectors corresponding to singular values of zero. Will V⁽⁰⁾Is selected as Q_1，i′。

In step 620, according to Q_1，i' and Ψ₃H_3，iObtain a satisfaction of psi₃H_3，iQ_1，i' 0Q_1，i″

The specific step may be to perform psi₃H_3，iQ_1，iSVD decomposition of's:

wherein Q is_1，iIs composed of⁽⁰⁾D of_1，iThe columns constitute.

In step 630, based on Q_1，i' and Q_1，i"calculate Q_1，i：

Q_1，i＝Q_1，i′Q_1，i″ (6)

Similarly, transmitter i is set from Ψ₁And Ψ₃In calculating Q_2，iFrom Ψ₁And Ψ₂In calculating Q_3，i。

Next, in step 520, the precoding unit 320 of the transmitter i is based on Q_j，iFor the signal s to be transmitted_i，jAnd (3) precoding:

X_j，i(t)＝Q_j，is_j，i(t) (7)

wherein s is_j，i(t) is the vector of signals transmitted by transmitter i to receiver j, X_j，i(t) is the precoded signal vector.

In step 530, transmitting section 330 of transmitter i transmits precoded signal X_j，i(t)。

The parameters used in the above steps may be stored in the first storage unit 360 in advance for being called when needed.

On the receiving side, in step 540, the second transceiver unit 410 of the receiver j receives the signal transmitted by the transmitter i, where the received signal is:

in step 550, the filtering unit 420 of each receiver j receives the filtering matrix Ψ_jAnd filtering is carried out, so that the interference of signals of other users can be eliminated. In the embodiment of the present invention, the three receiver-filtered signals are:

y₁＝ψ₁(H_1，1Q_1，1s_1，1+H_1，2Q_1，2s_1，2)+ψ₁n₁

y₂＝ψ₂(H_2，1Q_2，1s_2，1+H_2，2Q_2，2s_2，2)+ψ₂n₂

y₃＝ψ₃(H_3，1Q_3，1s_3，1+H_3，2Q_3，2s_3，2)+ψ₃n₃

it can be seen that due to the constraints from 1(a) to 3(b), only the signal and noise transmitted for the receiver remain in the received filtered signal. Then, due to H_j，i、Q_j，iAnd Ψ_jAs is known, in step 560, the codec unit 430 can easily extract the signals s respectively by joint decoding_i，jWherein H is, for example, in the case where the transmitter is a base station and the receiver is a mobile terminal_j，iAnd Q_j，iThe receiver can be informed by the transmitter via the downlink training sequence and stored in the second storage unit 460.

The parameters used in steps 540-560 may be stored in the second storage unit 460 for use when needed.

Also, it can be seen that only local CSI is used in embodiments of the present invention, i.e. each transmitter i only needs to know between itself and all receivers

The transmitters do not need to exchange channel information, so the method is not influenced by the transmission delay of a backbone network to the real-time performance of the CSI, reduces the requirement on the transmission bandwidth of the backbone network, and is more convenient to realize in an actual system.

The DoF performance of the decomposition algorithm described above is analyzed below.

In order to satisfy the constraints (1a) to (3b), there is a lower limit in the selection of the preprocessing matrix:

Q_1，imust be at Ψ₂H_2，iAnd Ψ₃H_3，iIn the intersection of the null spaces of (a);

Q_2，imust be at Ψ₁H_1，iAnd Ψ₃H_3，iIn the intersection of the null spaces of (a);

Q_3，imust be at Ψ₁H_1，iAnd Ψ₂H_2，iIn the intersection of the nulls of (a).

The following constraints are thereby created:

d_1，1≤M-(d_2，1+d_2，2)-(d_3，1+d_3，2) (9a)

d_2，1≤M-(d_1，1+d_1，2)-(d_3，1+d_3，2) (9b)

d_3，1≤M-(d_1，1+d_1，2)-(d_2，1+d_2，2) (9c)

d_1，2≤M-(d_2，1+d_2，2)-(d_3，1+d_3，2) (9d)

d_2，2≤M-(d_1，1+d_1，2)-(d_3，1+d_3，2) (9e)

d_3，2≤M-(d_1，1+d_1，2)-(d_2，1+d_2，2) (9f)

where M is the number of transmit antennas of the transmitter, assuming that the number of antennas of all transmitters is equal.

To obtain interference-free transmission, two constraints should also be considered: the total number of transmit data streams per transmitter cannot exceed the number of its transmit antennas and the total number of receive data streams per receiver cannot exceed the number of its receive antennas.

d_1，1+d_2，1+d_3，1≤M (10a)

d_1，2+d_2，2+d_3，2≤M (10b)

d_1，1+d_1，2≤N (11a)

d_2，1+d_2，2≤N (11b)

d_3，1+d_3，2≤N (11c)

Wherein, assuming that the number of antennas of all receivers is equal, N is the number of receiving antennas of the receiver.

When the constraints (9a) to (9f) are considered, the result is

When the constraints (10a) and (10b) are considered, the result is

When the constraints (11a) to (11c) are considered, the result is

Combining (12) - (14) suggests that the maximum attainable DoF is:

the above-described case of 3 receivers can be generalized to other cases, for example, the case of 4 receivers, and as with the above analysis, it can be deduced that in the case of 4 receivers:

η^*＝min(2M，4N，8M/7) (16)

whereas in the case of 2 receivers, the maximum achievable DoF is:

η^*＝min(2M，2N，4M/3) (17)

there is a problem that a better DoF can be obtained when the base station serves many mobile terminals at the same time. By comparing (15) and (17), it is clear that when the transmitter is a base station and the receiver is a mobile terminal, 3 mobile terminals can obtain a higher DoF than 2 mobile terminals only under the following conditions:

min(2M，3N，6M/5)＞min(2M，2N，4M/3)

equivalent to:

<math><mrow><mn>3</mn><mi>M</mi><mo>/</mo><mn>5</mn><mo>></mo><mn>2</mn><mi>N</mi><mo>&DoubleRightArrow;</mo><mi>M</mi><mo>></mo><mn>5</mn><mi>N</mi><mo>/</mo><mn>3</mn><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>18</mn><mo>)</mo></mrow></mrow></math>

likewise, comparing (15) and (16) can result in that 4 receivers can obtain a higher DoF than 3 mobile terminals under the following conditions:

<math><mrow><mn>8</mn><mi>M</mi><mo>/</mo><mn>7</mn><mo>></mo><mn>3</mn><mi>N</mi><mo>&DoubleRightArrow;</mo><mi>M</mi><mo>></mo><mn>21</mn><mi>N</mi><mo>/</mo><mn>8</mn><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>19</mn><mo>)</mo></mrow></mrow></math>

when N is 2, 3 mobile terminals are optimal when 6M is greater than 4, and 4 mobile terminals are optimal when 8M is greater than 6.

It should be noted that when the transmitter is a mobile terminal and the receiver is a base station, a person skilled in the art can easily derive the optimum number of mobile terminals from the above. For example, in this case, the DoF obtained according to the formula (15) can also be considered as the maximum DoF obtainable for 2 mobile terminals (transmitters).

It should be noted that when M-4 and N-3, the maximum achievable DoF is 4.8, while the achievable DoF (i.e. the number of independent data streams) must be an integer. This means that the DoF has to be rounded down, i.e. rounded down

Resulting in loss of DoF.

In another embodiment of the present invention, symbol spreading techniques may be used to solve this problem on the basis of the above.

On the transmitting side, the spreading unit 350 performs T-symbol spreading. Each transmitter i considers the symbols transmitted on the T slots or subcarriers as signals transmitted from T virtual antennas, and jointly precodes them, which will be

The data streams are precoded and transmitted over the T symbols. Similarly, a receiver considers the symbols received on the T slots or subcarriers as signals received from the T virtual antennas, and thus jointly receives them. Thus, the extended channel model can be expressed as:

<math><mrow><msub><mover><mi>y</mi><mo>&OverBar;</mo></mover><mi>j</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><munderover><mi>Σ</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mn>2</mn></munderover><msub><mover><mi>H</mi><mo>&OverBar;</mo></mover><mrow><mi>j</mi><mo>,</mo><mi>i</mi></mrow></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><msub><mover><mi>x</mi><mo>&OverBar;</mo></mover><mi>i</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>+</mo><msub><mover><mi>n</mi><mo>&OverBar;</mo></mover><mi>j</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>20</mn><mo>)</mo></mrow></mrow></math>

wherein,

is a transmitted signal vector on the t-th extension channel, the dimension of the column vector is TM x 1,which contains T symbol vectors of dimension mx 1 transmitted over T slots/subcarriers,

and

respectively representing the received signal vector, channel matrix and noise vector on the extension channel.

In an extended channel, precoding unit 320 in transmitter i uses a dimension of TM d_iOf the precoding matrix Q_i＝[Q_1，i Q_2，i Q_3，i]Will d_iA single independent data stream

Precoding to form TM transmission data streams, namely:

<math><mrow><msub><mover><mi>x</mi><mo>&OverBar;</mo></mover><mi>i</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><munderover><mi>Σ</mi><mrow><mi>k</mi><mo>=</mo><mn>1</mn></mrow><msub><mi>d</mi><mi>i</mi></msub></munderover><msubsup><mi>s</mi><mi>i</mi><mrow><mo>(</mo><mi>i</mi><mo>)</mo></mrow></msubsup><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><msub><mi>q</mi><mrow><mi>i</mi><mo>,</mo><mi>k</mi></mrow></msub><mo>=</mo><msub><mi>Q</mi><mi>i</mi></msub><msub><mi>s</mi><mi>i</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>21</mn><mo>)</mo></mrow></mrow></math>

wherein each Q_j，iAre generated by using methods similar to (4) to (6) for the extension channel,

is that

The t-th symbol in (1), and

q_i，kis Q_iK column of (2), Q_iComprises all that

The corresponding precoding vector. After symbol spreading, the transmit and receive antennas are enlarged by a factor of T. To get an integer value of DoF, according to (15), (16) and (17), T is chosen to be a multiple of 3 for 2 receivers, 5 for 3 receivers and 7 for 4 receivers. Normalized DoF per channel user of

Accordingly, at the receiving side, the codec unit 430 of the receiver decodes the signal vector to obtain the signal vector

The extraction unit 440 extracts from s_iAnd (t) recovering the signal before spreading.

The following illustrates in simulation the advantages of embodiments of the present invention with respect to other techniques. In this simulation, two transmitters, each having two transmit antennas, and two receivers, each having two receive antennas, were used. The channel between each pair of transmitter and receiver is an independent identically distributed rayleigh fading channel and has the same path loss. And shannon's formula was used to calculate capacity. The total capacity of all receivers averaged over a large number of channel realizations is shown in the figure.

In fig. 7, scheme 1 represents a technical solution proposed by an embodiment of the present invention, where each transmitter transmits 2 data streams to each receiver in 3 symbol periods using symbol spreading with T ═ 3.

Scheme 2 represents a Co-MIMO solution, without using symbol spreading. Wherein each transmitter transmits 1 data stream to each receiver within one symbol period and block diagonalization (block diagonalization) is used to avoid interference between users.

Scheme 3 is an interference alignment technique (interference alignment) combined with a symbol extension of T3, where each transmitter sends 2 data streams to each receiver in three symbol periods.

As can be seen from fig. 7, scheme 1 has an advantage over both scheme 2 and scheme 3 over a wide SNR range.

Those skilled in the art will readily recognize that for the case where the base station acts as a receiver and the mobile terminal acts as a transmitter, the only difference is that the separate channels after the X signal decomposition are broadcast channels rather than MA channels.

Those skilled in the art will readily recognize that the different steps of the above-described method may be implemented by programming a computer. Herein, some embodiments also include machine-readable or computer-readable program storage devices (e.g., digital data storage media) and encoding machine-executable or computer-executable program instructions, wherein the instructions perform some or all of the steps of the above-described methods. For example, the program storage device may be digital memory, magnetic storage media (such as magnetic disks and tapes), hardware, or optically readable digital data storage media. Embodiments also include programmed computers that perform the steps of the above-described methods.

The description and drawings merely illustrate the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples mentioned herein are explicitly primarily for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically mentioned examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

The above description is only for implementing the embodiments of the present invention, and those skilled in the art will understand that any modification or local replacement without departing from the scope of the present invention shall fall within the scope defined by the claims of the present invention, and therefore, the scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A transmission method for use in an X channel comprised of a plurality of receivers and a plurality of transmitters, the method comprising:

generating a precoding matrix for each of the plurality of receivers;

precoding signal vectors to be transmitted to the plurality of receivers according to a corresponding one of the precoding matrices;

transmitting the precoded signal vectors to the plurality of receivers.

2. The method of claim 1, wherein:

the precoding matrix is generated for an extension channel composed of a plurality of (T) time slots or subcarriers, and the number of transmitting antennas and the number of receiving antennas of the extension channel are T times of the number of original channels;

the precoding signal vectors to be transmitted to the plurality of receivers according to a corresponding one of precoding matrices includes:

precoding a signal vector according to a corresponding one of the precoding matrices of the extended channel;

the transmitting the precoded signal vectors to the plurality of receivers includes:

and transmitting the precoded signal vectors to a plurality of receivers on the extended channel.

3. The method of claim 1 or 2, further comprising:

selecting the number of mobile terminals capable of obtaining the maximum degree of freedom according to the number of antennas of the transmitters and the receivers;

the generating a precoding matrix for each of the plurality of receivers comprises:

generating a precoding matrix for each of the plurality of receivers based on the selected number of mobile terminals.

4. The method of claim 3, further comprising:

when the plurality of transmitters are base stations and the plurality of receivers are mobile terminals, receiving uplink sounding signals from the plurality of receivers, the uplink sounding signals containing information of a filter matrix for a corresponding one of the plurality of receivers, the filter matrix being used by the corresponding one of the plurality of receivers to filter out signal vectors sent by the plurality of transmitters to other receivers;

estimating channel information between each receiver and the received uplink sounding signal, the channel information including information of a filter matrix of a corresponding one of the plurality of receivers,

wherein said generating a precoding matrix for each of said plurality of receivers based on the selected number of mobile terminals comprises:

and precoding the receiver according to the selected number of the receivers by using the estimated channel information containing the filter matrix information.

5. A transmission method for use in an X channel comprised of a plurality of receivers and a plurality of transmitters, the method comprising:

receiving signal vectors from the plurality of transmitters;

filtering out signal vectors transmitted to other receivers of the plurality of receivers from the received signal vectors;

decoding the filtered signal vectors to recover respectively useful signal vectors precoded in the plurality of transmitters using a precoding matrix.

6. The method of claim 5, wherein the received signal vectors are combined from received signal vectors over multiple time slots or subcarriers.

7. The method of claim 5, further comprising:

generating a filter matrix, transmitting the filter matrix to the plurality of transmitters so that the plurality of transmitters can precode a plurality of receivers according to the filter matrix;

said filtering out signal vectors transmitted to other receivers of said plurality of receivers from among the received signal vectors comprises:

and filtering out the signal vectors transmitted to other receivers in the plurality of receivers from the received signal vectors by using the filter matrix.

8. A transmitter for use in an X channel comprised of a plurality of receivers and a plurality of transmitters, the transmitter comprising:

a precoding matrix generating unit, configured to generate corresponding precoding matrices for the plurality of receivers;

a precoding unit configured to precode signal vectors to be transmitted to the plurality of receivers according to a corresponding one of the precoding matrices; and

and the first transceiving unit is used for transmitting the precoded signal vector.

9. The transmitter of claim 8, further comprising:

and the extension unit is used for transmitting the precoded signal vector on a plurality of time slots or subcarriers.

10. The transmitter of claim 9, further comprising:

a selecting unit configured to select the number of mobile terminals capable of obtaining the maximum degree of freedom according to the respective numbers of antennas of the plurality of transmitters and the plurality of receivers;

and the precoding matrix generating unit is used for generating corresponding precoding matrixes for the plurality of receivers according to the number of the selected mobile terminals.

11. A receiver for use in an X channel comprised of a plurality of receivers and a plurality of transmitters, the receiver comprising:

a second transceiving unit for receiving signal vectors from the plurality of transmitters;

a filtering unit, configured to filter out signal vectors that are transmitted to other receivers in the plurality of receivers from among the received signal vectors; and

a coding and decoding unit, configured to decode the filtered signal vectors to respectively recover the useful signal vectors precoded by using the precoding matrix in the plurality of transmitters.

12. The receiver of claim 11, further comprising:

a matrix generating unit for generating a filter matrix;

if the receivers are mobile terminals, the second transceiver unit is further configured to send the uplink sounding signals subjected to the conjugate transpose precoding of the filter matrix to the transmitters, so that the transmitters can obtain channel information including the filter matrix, and precode the receivers by using the channel information;

the filtering unit is further configured to filter, by using the filtering matrix, signal vectors transmitted to other receivers in the plurality of receivers from among the received signal vectors.

13. A communication system comprising a plurality of transmitters according to any of claims 8 to 10 and a plurality of receivers according to claim 11 or 12.