WO2011050543A1

WO2011050543A1 - Method and device for obtaining downlink channel status information

Info

Publication number: WO2011050543A1
Application number: PCT/CN2009/074752
Authority: WO
Inventors: 张晓博; 石璟; 尤明礼
Original assignee: 上海贝尔股份有限公司; 阿尔卡特朗讯
Priority date: 2009-11-02
Filing date: 2009-11-02
Publication date: 2011-05-05
Also published as: CN102598731B; CN102598731A

Abstract

A technical solution for a base station obtaining channel status information of all downlinks is provided in the present invention. Wherein, for a downlink wireless communication link, which is from a base station to an antenna sending uplink reference signal of a user terminal, according to reciprocity of a Time Division Duplex wireless communication system, the base station obtains the channel status information for the downlink wireless communication link based on the received uplink reference signal; and for a downlink wireless communication link, which is from the base station to the antenna receiving signal only without sending signal of the user terminal, the user terminal determines a precoding matrix called the part precoding matrix, and sends the indicator of the precoding matrix to the base station; so that the base station is enabled to obtain the channel status information for all of the downlink wireless communication links.

Description

Obtain downlink channel status information

Method and device

The present invention relates to a time division multiplexed wireless communication network, and more particularly to a method and apparatus for a base station in a time division multiplexed wireless communication network to obtain downlink channel state information to a user terminal. Background technique

Time Division Duplexing (TDD) The reciprocity of the channel of a wireless communication system is known to reduce the feedback of the uplink in MIMO and Coordinated Multipoint Transmission (CoMP), according to the above uplink channel sounding signal In the form of channel state information feedback, the base station can perform non-codebook based precoding. In the LTE-A wireless communication network, when the number of receiving antennas of the user terminal is greater than the number of transmitting antennas, or when the uplink channel sounding reference signal (SRS) is insufficient for use (ie, it should be M channel sounding reference signals are transmitted on M antennas, and actually only N channel sounding reference signals are transmitted on N antennas, M is greater than N), and the base station detects channel state information in the form of reference signal through the uplink channel channel. Feedback, only the channel information of part of the downlink is known. How the base station obtains all the channel state information of the downlink becomes an urgent problem to be solved.

At present, the channel state information feedback of the time division multiplexing wireless communication system mainly has the following two methods: the quantized channel state information feedback and the statistical channel state information feedback. The quantized channel state information feedback means that the user terminal performs channel estimation according to the received downlink reference signal to obtain a quantized channel transmission matrix and feeds back to the base station, and performs feedback every 5 ms or so. The disadvantage of this method is that the amount of data of the quantized channel transmission matrix is very large, consuming a lot of wireless bandwidth resources. The statistical channel state information feedback is that the user terminal refers to feedback the covariance matrix of the channel transmission matrix to the base station, and performs feedback once every long time, for example, about 200 ms. Compared with the quantized channel state information feedback, the method reduces the amount of data to be fed back, but the method is only applicable to wireless communication systems with strong channel correlation. For wireless communication systems with weak channel correlation, Not applicable. Summary of the invention

The number of antennas used by the user terminal to transmit the uplink reference signal in the time division multiplexing wireless communication system is smaller than the number of antennas used to receive the signal, and the antenna for receiving the signal includes an antenna for transmitting the uplink reference signal, The present invention provides a technical solution for a base station to acquire channel state information of all downlinks: a downlink wireless communication link between antennas for transmitting an uplink reference signal from a base station to a user terminal, and reciprocity according to a time division multiplexing wireless communication system The base station acquires channel state information of the downlink wireless communication link according to the received uplink reference signal; and the downlink wireless communication link between the antennas for the base station to the user terminal only for receiving signals and not transmitting signals, the user The terminal determines a precoding matrix, called a partial precoding matrix, and transmits an indicator of the precoding matrix to the base station; thus, the base station obtains channel state information of all downlink wireless communication links.

According to an embodiment of the present invention, a method for a base station to acquire downlink channel state information to a user terminal in a multi-antenna user terminal of a time division multiplexed wireless communication network is provided, wherein the user terminal is configured to send The number of antennas of the uplink reference signal is smaller than the number of antennas for receiving signals, and the antenna for receiving signals includes an antenna for transmitting an uplink reference signal, the method comprising the steps of: transmitting an uplink reference signal to the base station; And transmitting a partial precoding matrix indicator corresponding to at least one antenna for receiving only the signal and not for transmitting the uplink reference signal to the base station.

According to another embodiment of the present invention, there is provided a method for acquiring downlink channel state information of a plurality of antenna user terminals thereof in a base station of a time division multiplexed wireless communication network, wherein the user terminal is configured to send an uplink reference signal The number of antennas is smaller than the number of antennas for receiving signals, and the antenna for receiving signals includes an antenna for transmitting an uplink reference signal, the method comprising the steps of: receiving an uplink reference signal from the user terminal, And receiving a partial precoding matrix indicator corresponding to at least one antenna of the user terminal only for receiving a signal and not for transmitting an uplink reference signal; determining, by the received uplink reference signal, the base station to the user terminal A transmission matrix of a portion of the downlink channel corresponding to the antenna for transmitting the uplink reference signal.

According to still another embodiment of the present invention, a time division multiplexing wireless communication network is provided The apparatus for the base station to obtain the downlink channel state information of the user terminal in the multi-antenna user terminal, wherein the number of antennas used by the user terminal to send the uplink reference signal is smaller than the number of antennas used for receiving the signal, And the antenna for receiving the signal includes an antenna for transmitting an uplink reference signal, where the apparatus includes: a first sending device, configured to send an uplink reference signal to the base station; and a transmitting and receiving signal only for not transmitting the uplink A partial precoding matrix indicator corresponding to at least one antenna of the reference signal to the base station.

According to still another embodiment of the present invention, there is provided an apparatus for acquiring downlink channel state information of a plurality of antenna user terminals in a base station of a time division multiplexed wireless communication network, wherein the user terminal is configured to send an uplink reference The number of antennas of the signal is smaller than the number of antennas for receiving the signal, and the antenna for receiving the signal includes an antenna for transmitting the uplink reference signal, the obtaining means includes: a second receiving device, configured to receive from the An uplink reference signal of the user terminal, and a partial precoding matrix indicator corresponding to at least one antenna of the user terminal for receiving only a signal and not for transmitting an uplink reference signal; third determining means, configured to receive The obtained uplink reference signal determines a transmission matrix of a part of the downlink channel corresponding to the antenna for transmitting the uplink reference signal from the base station to the user terminal.

By using the method and the device of the present invention, the problem of how the base station learns the channel state information of all the downlink channels in the case that the number of receiving antennas of the user terminal is greater than the number of transmitting antennas is effectively solved, and the wireless of the uplink wireless communication link is saved. Bandwidth resources. The method and apparatus of the present invention bridges the gap between a time division multiplexing wireless communication system and a frequency division multiplexing wireless communication system by utilizing a precoding matrix in a frequency division multiplexing system. Moreover, the method and apparatus for obtaining, by the base station, channel state information between the user terminals in the present invention are not affected by channel correlation. 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 network topology of a time division duplex wireless communication network according to an embodiment of the present invention; 2 is a flowchart of a method for a base station in a time division multiplexed wireless communication system to acquire downlink channel state information of a multi-antenna user terminal under its jurisdiction according to an embodiment of the present invention;

3 is a partial precoding matrix indicator corresponding to at least one antenna for determining only a received signal and not for transmitting an uplink reference signal in a user terminal of a time division multiplexed wireless communication system, in accordance with an embodiment of the present invention. Method flow chart; FIG. 4 is a network topology diagram of a time division multiplexing wireless communication system according to another embodiment of the present invention;

5 is a flowchart of precoding in a base station of a time division duplex wireless communication system for transmitting a signal to be transmitted to a user terminal according to downlink channel state information between the user terminals, in accordance with an embodiment of the present invention;

6 is a diagram for a base station to acquire a user terminal to a user terminal in a multi-antenna user terminal of a time division multiplexed wireless communication network in a user terminal of a time division wireless communication system according to an embodiment of the present invention; A schematic structural diagram of an apparatus 600 for downlink channel state information;

FIG. 7 is a schematic structural diagram of an apparatus 700 for acquiring downlink channel state information of a plurality of antenna user terminals in a base station of a time division multiplexed wireless communication network according to an embodiment of the present invention; FIG.

FIG. 8 is a schematic diagram of channel capacity simulation under different channel state information feedback schemes when the time division multiplexed wireless communication system shown in FIG. 1 is an LTE-A wireless communication system; wherein the same or similar reference numerals indicate the same or Similar step features or devices (modules). detailed description

The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. 1 shows a network topology diagram of a time division multiplexed wireless communication system in accordance with an embodiment of the present invention. In Fig. 1, a base station 10 has four antennas 11, 12, 13 and 14, each of which can be used for transmitting and receiving signals, and a user terminal 20 having two antennas 21 and 22, wherein antennas 21 and 22 are for receiving signals. , antenna 21 is only used for sending Signal.

2 is a flowchart of a method for a base station in a time division multiplexed wireless communication system to acquire downlink channel state information of a multi-antenna user terminal under its jurisdiction according to an embodiment of the present invention, where the user terminal is configured to send The number of antennas of the uplink reference signal is smaller than the number of antennas used to receive the signal, and the antenna for receiving the signal includes an antenna for transmitting the uplink reference signal. The case where the number of antennas used by the user terminal to transmit the uplink reference signal is smaller than the number of antennas used for receiving the signal includes at least the following two application scenarios. One is that the number of antennas for transmitting signals of the user terminal is smaller than the received signal. The number of antennas, and the other is that if the uplink reference signal of the uplink channel sounding reference signal (SRS) is not enough, the M channel sounding reference signals should be transmitted on the M antennas. Since the radio resources for transmitting the uplink reference signal are tight or the uplink reference signal is small, only N channel sounding reference signals are transmitted on N antennas, and M is greater than N.

The flowchart shown in FIG. 2 is described in detail below with reference to FIG. 1. It should be understood by those skilled in the art that the description is only for the purpose of illustrating the specific embodiments of the present invention, and is not to be construed as limit.

First, in step S201, the user terminal 20 transmits an uplink reference signal to the base station 10 using the antenna 21. The role of the uplink reference signal mainly lies in the base station performing uplink channel quality detection and uplink channel estimation, and is used for coherent detection and demodulation of the base station. For different wireless communication systems, the specific name of the uplink reference signal may be different. For the LTE-A wireless communication system, the uplink reference signal includes a channel sounding reference signal and a DeModulation Reference Signal (DM RS).

Due to the reciprocity of the time division multiplexed wireless communication system, that is, the symmetry of the uplink and downlink channels, the channel state information of the uplink channel between the antenna 21 to the antennas 11, 12, 13 and 14 obtained by the base station 10 according to the uplink reference signal, for example, the channel The estimated value can be regarded as channel state information of the downlink channel between the antennas 11, 12, 13, and 14 to the antenna 21.

Then, in step S202, the user terminal 20 transmits a partial precoding matrix indicator (PMI) corresponding to at least one antenna 22 for receiving only the signal and not for transmitting the uplink reference signal to the base station 10. It should be noted that, in the flow shown in FIG. 2, the execution of step S201 and step S202 is in no particular order, and step S201 may also be performed after step S202 or together with step S202.

For the situation shown in Figure 1, the base station 10 acquires the antenna through the uplink reference signal.

Channel state information of the downlink channel between 11, 12, 13 and 14 to the antenna 21, channel state information of the downlink channel between the antennas 11, 12, 13 and 14 to the antenna 22, transmitted by the base station 10 through the user terminal 20. Obtaining the antenna 11 by partially precoding the matrix indicator,

Channel state information for the downlink channel between 12, 13 and 14 to antenna 22. It should be noted that since the downlink channel between the antennas 11, 12, 13 and 14 to the antenna 22 is only a part of the downlink channel between the base station 10 and the user terminal 20, the antennas 11, 12, 13 and 14 to the antenna 22 are The precoding matrix corresponding to the downlink channel between them is called a partial precoding matrix.

3 illustrates a partial precoding matrix corresponding to at least one antenna for determining a received signal only for transmitting an uplink reference signal in a user terminal of a time division multiplexed wireless communication system, in accordance with an embodiment of the present invention. A method flow diagram of the indicator. The method flow for determining the partial precoding matrix indicator corresponding to the antenna 22 in the user terminal 20 shown in FIG. 1 will be described in detail below with reference to FIG.

First, in step S301, the user terminal 20 receives the downlink reference signal from the base station 10. The downlink reference signal is mainly used for downlink channel quality detection; downlink channel estimation, for coherent detection and demodulation of user terminals; and cell search. For different wireless communication systems, the specific name of the downlink reference signal may be different. For the LTE-A wireless communication system, the downlink reference signal includes a Channel Status Information Reference Signal (CSI-RS).

Next, in step S302, the user terminal 20 determines a downlink channel transmission matrix according to the downlink reference signal. Specifically, how to determine the downlink channel transmission matrix based on the downlink reference signal is a very mature technology in the art, for example, using Wiener filtering, Robust MMSE, etc., see Ye (Geoffrey) Li, Leonard J. Cimini, Jr. , and Nelson R. SoUenberger, Robust Channel Estimation for OFDM Systems with Rapid Dispersive Fading Channels, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 46, NO. 7, JULY 1998, the present invention will not be described in detail herein.

Finally, in step S303, the user terminal 20 determines a partial precoding matrix indicator corresponding to the antenna 22 according to the downlink channel transmission matrix determined in step S302 and the principle of maximizing the channel transmission capacity, that is, the antennas 11, 12 in the base station 10. A partial precoding matrix indicator corresponding to the downlink channel between 13 and 14 to antenna 22. In one embodiment, a mapping table of the same precoding matrix and its indicators is pre-stored in base station 10 and user terminal 20.

Specifically, there are many ways for the user terminal 20 to determine a partial precoding matrix, which are exemplified one by one.

In one embodiment, the user terminal 20 determines a partial precoding matrix by maximizing the determinant value of (Hw).(Hw)", where W is the one of the downlink channel transmission matrix corresponding to the antenna used to transmit the signal A matrix composed of partial vectors is subjected to matrix singular value decomposition to obtain a precoding matrix composed of a first to m column vector of a right 酉 singular matrix and a partial precoding matrix to be determined, and H is a downlink channel transmission matrix. Application scenario, m=l. Specifically,

Where hij represents the channel transmission coefficient between the jth antenna of the base station 10 and the ith antenna of the user terminal 20, i=l, 2; j=l, 2, 3, 4.

Where HP = (h _u h _n h _{l3 4} ) is a matrix composed of the part of the downlink channel transmission matrix corresponding to the antenna 21 for transmitting the signal, and the singular value decomposition is performed on the HP.

Where ui is a 1x1 matrix, ^∑ ' is a 1x4 matrix, VI is a 4x4 matrix, taking the first 歹' j V of the VI, let c be the partial precoding matrix to be determined, and c be the 4x1 matrix, Then W=[vc] is a precoding matrix, that is, an equivalent matrix of the precoding matrix of the signal transmitted by the base station 10 to the user terminal 20. In a specific embodiment, c is selected from a predetermined precoding codebook set C, and the precoding codebook that maximizes the determinant value is selected by traversing the precoding codebook in the codebook set C, the precoding The codebook constitutes the partial precoding matrix described above, as shown in the following equation: c = max(det( -W)-(H- W) ^H )

c ^eC ( 1 ) In another embodiment, W is a downlink channel transmission matrix H and is used for transmitting a signal The conjugate transposed matrix of the matrix HP composed of the antenna corresponding to the antenna of the number is subjected to QR decomposition to obtain the first to m-column vector of the conjugate transposed matrix of the orthogonal matrix and the pre-coding matrix to be determined. Encoding matrix. For the application scenario shown in Figure 1, m is 1. Specifically, =„ , where ^ ^ is a _4x4 matrix, which is a 4x 1 matrix, taking the first column q, q and c to form a precoding matrix W, ie W=[qc].

In another embodiment, the partial precoding matrix c is determined by maximizing the value of the smallest one of the singular values obtained by performing the matrix singular value decomposition of (H.W), wherein W is a transmission matrix according to the downlink channel. a matrix consisting of the part of the vector corresponding to the m antennas used for transmitting the signal, and the first to the m-column vectors of the right-hand singular matrix obtained by the matrix singular value decomposition and the partial precoding matrix to be determined are pre-coded. matrix. For the application scenario shown in Figure 1, m is 1.

In another embodiment, the partial precoding matrix is determined by causing (the smallest element of the triangular matrix diagonal elements obtained after QR decomposition is maximized, wherein w is a transmission matrix according to a downlink channel. a conjugate transposed matrix of a matrix 组成 composed of the partial vectors corresponding to the m antennas used to transmit the signal (Hpf

The first to m column vectors of the conjugate transposed matrix of the orthogonal matrix obtained by QR decomposition and the partial precoding matrix to be determined constitute a precoding matrix. For the application scenario shown in Figure 1, m is 1.

4 is a diagram showing a network topology of a time division multiplexed wireless communication system in accordance with another embodiment of the present invention. In FIG. 4, the base station 10 has four antennas 11, 12, 13, and 14, each of which can be used to transmit and receive signals, and the user terminal 20 has four antennas 21, 22, 23, and 24, wherein the antennas 21, 22, 23 and 24 are for receiving signals, and antennas 21 and 22 are for transmitting signals only. The process of how the user terminal 20 determines the partial precoding matrix indicators corresponding to the antennas 23 and 24 in the application scenario shown in FIG. 4 will be described in detail below.

In one embodiment, the user terminal 20 determines a partial precoding matrix by maximizing the determinant value of H - w) w) ^H , where W is the portion of the downlink channel transmission matrix corresponding to the antenna used to transmit the signal Matrix singular value decomposition A precoding matrix composed of a first to m column vector of the right 酉 singular matrix and a partial precoding matrix to be determined, and H is a downlink channel transmission matrix. For the application scenario shown in Figure 4, m=2.

Specifically, H = , where h _y represents the jth day of the base station 10

The channel transmission coefficient between the line to the i-th antenna of the user terminal 20, i, j = l, 2, 3, 4.

Wherein, HP = is a matrix composed of the partial vectors corresponding to the antennas 21 and 22 for transmitting signals in the downlink channel transmission matrix, and singular value decomposition is performed on the HP to obtain H:^/^^, where is a 2x2 matrix, Is a 2x4 matrix, V! Is a 4x4 matrix, taking the first to second column vector V, let c be the partial precoding matrix to be determined, c is a 4x2 matrix, then W=[vc] is the precoding matrix, that is, the base station 10 pairs send An equivalent matrix of precoding matrices of signals to user terminal 20. In a specific embodiment, c is selected from a predetermined precoding codebook set C, and the precoding codebook that maximizes the determinant value is selected by traversing the precoding codebook in the codebook set C, the precoding The codebook constitutes the partial precoding matrix described above, as shown in equation (1).

In another embodiment, W is a conjugate transposed matrix of the orthogonal matrix obtained by QR decomposition of the conjugate transpose of the matrix 组成 of the partial vector corresponding to the antenna for transmitting the signal in the downlink channel transmission matrix Η The precoding matrix consisting of the first to second column vectors and the partial precoding matrix to be determined. Specifically, (HP) ^H - QA' HP

Where ^ is a 4x4 matrix, which is a 2x4 matrix, taking the first to m column vectors q, q and c to form a precoding matrix W, ie W = [qc]. For the application scenario shown in Figure 4, m takes the value 2.

In another embodiment, the partial precoding matrix c is determined by maximizing the value of the smallest one of the singular values obtained by performing the matrix singular value decomposition of (H.W), wherein W is a transmission matrix according to the downlink channel. Η中与m antenna pairs for transmitting signals The matrix HP composed of the partial vector is subjected to matrix singular value decomposition to obtain the first to m column vectors of the right 酉 singular matrix and the partial precoding matrix to be determined to form a precoding matrix. For the application scenario shown in Figure 4, m takes the value 2.

In another embodiment, the partial precoding matrix is determined by maximizing the value of the smallest of the triangular matrix diagonal elements obtained by QR decomposition, wherein W is transmitted according to the downlink channel. The conjugate transposed matrix of the matrix HP composed of the partial vector corresponding to the m antennas for transmitting signals in the matrix H is subjected to QR decomposition to obtain the conjugate transposed matrix of the orthogonal matrix, the first to m-column vectors and to be determined The partial precoding matrix constitutes a precoding matrix. For the application scenario shown in Figure 4, m is 2.

It should be noted that, for the application scenario shown in FIG. 4, if the user terminal 20 transmits the uplink reference signal by using the antennas 21 and 23, the process of determining the partial precoding matrix by the user terminal 20 and the user terminal 20 transmitting by using the antennas 21 and 22 The process of determining the uplink reference signal is similar, and the logical mapping relationship between the antenna 22 and the antenna 23 and the row in the channel transmission matrix may be reversed.

It should be noted that the manner in which the user terminal 20 determines the partial precoding matrix indicator according to the principle of maximizing the channel transmission capacity has various representations, and is not limited to the maximum determinant of the matrix (HH) described above, or the matrix. (H.) The largest singular value after singular value decomposition, or the matrix (H) after QR decomposition, the smallest element of the triangular matrix diagonal element has the largest value; for example, it can also maximize the signal to interference and noise ratio And other forms of expression to determine.

After receiving the uplink reference signal sent by the user terminal 20 in step S201, the base station 10 determines the transmission of part of the downlink channel between the base station 10 and the user terminal 20 according to the uplink reference signal and the symmetry of the channel of the time division multiplexed wireless communication system. matrix. For the application scenario shown in FIG. 1, a partial downlink channel transmission matrix H = (/^ h _u h _u A ₁₄ ) between the antennas 11, 12, 13 and 14 to the antenna 21 is obtained. For the application scenario shown in FIG. 4, the transmission matrix of the partial downlink channel between the antennas 11, 12, 13 and 14 to the antennas 21 and 22 is obtained.

After obtaining the channel state signal of the downlink channel between the user terminal 10 and the user terminal 10, the base station 10 may pre-code the signal to be sent to the user terminal 20 according to the channel state information. code. 5 illustrates a signal in a base station of a time division duplex wireless communication system for transmitting a signal to be transmitted to a user terminal based on a downlink channel state signal between the user terminal and the user terminal, in accordance with an embodiment of the present invention. Coded flow chart. The flow in FIG. 3 will be described in detail below with reference to FIG. 1.

First, in step S501, the base station performs matrix singular value decomposition on the transmission matrix HP of the partial downlink channel to obtain the first to m column vectors of the right 酉 singular matrix; or conjugates to the transmission matrix HP of the partial downlink channel The device matrix performs QR decomposition to obtain the first to m-column vectors of the conjugate device matrix of the decomposed orthogonal matrix, where m is the number of antennas used for transmitting signals in the user terminal 20, for the application shown in FIG. Scene, m=l; For the application scenario shown in Figure 4, m=2.

Next, in step S502, the base station 20 uses the first to m-column vectors obtained in step S501 and the partial precoding matrix c indicated by the partial precoding matrix indicator received from the user terminal 20 in step S202 to form a pre- The coding matrix W precodes the signal to be transmitted to the user terminal 20. For the application scenario shown in Figure 1, the partial precoding matrix c corresponds to a portion of the downlink channel between the antennas 11, 12, 13 and 14 to the antenna 22, and c is a 4x1 matrix. For the application scenario shown in Figure 4, the partial precoding matrix c corresponds to a portion of the downlink channels between the antennas 11, 12, 13 and 14 to the antennas 23 and 24, and c is a 4x2 matrix.

Optionally, the base station 20 may also use the downlink channel state information to determine the coherence (or correlation) of the channel, thereby determining the number of code streams RI ( Rank Indicator) of the signal to be transmitted to the user terminal 20. In one embodiment, after the base station 20 performs matrix singular value decomposition on the precoding matrix W, it is determined that the number of singular values greater than a predetermined threshold is the number of code streams to be transmitted. After the number of code streams is determined by RI, the pre-RI columns corresponding to the precoding matrix W are selected to form the precoding matrix actually used. The predetermined threshold can be set differently depending on the performance of different wireless communication systems. Of course, the number of transport streams in the base station 10 can also be determined by the user terminal 20 and fed back to the base station 10.

6 illustrates a user terminal in a time division duplex wireless communication system for use in a multi-antenna user terminal of a time division multiplexed wireless communication network for base station acquisition of the user in the user terminal of the time division duplex wireless communication system, in accordance with an embodiment of the present invention. Device for downlink channel state information of terminal Schematic diagram of the structure of 600. The number of antennas used by the user terminal to send the uplink reference signal is smaller than the number of antennas used for receiving the signal, and the antenna for receiving the signal includes an antenna for transmitting the uplink reference signal.

The device 600 includes a first transmitting device 601, a first receiving device 602, a first determining device 603, and a first transmitting device 604. It should be noted that the working process of the device 600 located in the user terminal 20 will be described in detail below with reference to FIG.

The first transmitting device 601 transmits an uplink reference signal to the base station 10 using the antenna 21. The role of the uplink reference signal mainly lies in the base station performing uplink channel quality detection and uplink channel estimation, and is used for coherent detection and demodulation of the base station. For different wireless communication systems, the specific name of the uplink reference signal may be different. For the LTE-A wireless communication system, the uplink reference signal includes a channel sounding reference signal and a DeModulation Reference Signal (DM RS).

The first transmitting device 604 also transmits a partial Precoding Matrix Indicator (PMI) corresponding to at least one antenna 22 for receiving signals only for transmitting the uplink reference signal to the base station 10.

The process of determining a partial precoding matrix indicator corresponding to at least one antenna for receiving signals only for transmitting the uplink reference signal in the user terminal 20 will be described below.

In one embodiment, the first receiving device 601 receives the downlink reference signal from the base station 10. The downlink reference signal is mainly used for downlink channel quality detection; downlink channel estimation, for coherent detection and demodulation of user terminals; and cell search. For different wireless communication systems, the specific name of the downlink reference signal may be different. For the LTE-A wireless communication system, the downlink reference signal includes a Channel Status Information Reference Signal (CSI-RS).

Next, the first determining device 602 determines a downlink channel transmission moment according to the downlink reference signal. Array. Specifically, how to determine the downlink channel transmission matrix based on the downlink reference signal is a very mature technology in the art, for example, using Wiener filtering, Robust MMSE, etc., see Ye (Geoffrey) Li, Leonard J. Cimini, Jr. , and Nelson R. SoUenberger, Robust Channel Estimation for OFDM Systems with Rapid Dispersive Fading Channels, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 46, NO. 7, JULY 1998, the present invention will not be described in detail herein.

Finally, the second determining means 603 determines a partial precoding matrix indicator corresponding to the antenna 22 according to the downlink channel transmission matrix determined by the first determining means 602 and the principle of maximizing the channel transmission capacity, that is, the antennas 11, 12, 13 in the base station 10. And a partial precoding matrix indicator corresponding to the downlink channel between 14 and antenna 22. In one embodiment, a mapping table of the same precoding matrix and its indicators is pre-stored in base station 10 and user terminal 20.

Specifically, the second determining means 603 determines a part of the precoding matrix in a plurality of ways, which are exemplified one by one.

In one embodiment, the second determining means 603 determines a partial precoding matrix by maximizing the determinant value of (H HH )", where W is the portion of the downlink channel transmission matrix corresponding to the antenna used to transmit the signal The matrix composed of vectors is subjected to matrix singular value decomposition to obtain a precoding matrix composed of a first to m column vector of a right 酉 singular matrix and a partial precoding matrix to be determined, and Η is a downlink channel transmission matrix.

For the application scenario shown in Figure 1, m = l. specifically,

Where hy represents the channel transmission coefficient between the jth antenna of the base station 10 and the ith antenna of the user terminal 20, i = 1, 2; j = 1, 2, 3, 4.

Wherein, HP = i _n h _u h _u / _{3⁄4 4} ) is a matrix composed of the partial vector corresponding to the antenna 21 for transmitting the signal in the downlink channel transmission matrix, and the singular value decomposition is performed on the ΗΡ

, where is a 1 x 1 matrix, ∑, is a 1 x 4 matrix, is a 4x4 matrix, takes the first column V, let c be the partial precoding matrix to be determined, c is a 4x 1 matrix, Then W=[vc] is a precoding matrix, that is, an equivalent matrix of the precoding matrix of the signal transmitted by the base station 10 to the user terminal 20. In one In an embodiment, c is selected from a predetermined precoding codebook set C, and the precoding codebook that maximizes the determinant value is selected by traversing the precoding codebook in the codebook set C, the precoding codebook That is, the partial precoding matrix described above is constructed as shown in the formula (1).

In another embodiment, W is a conjugate transpose of the orthogonal matrix obtained by QR decomposition of the conjugate transposed matrix of the matrix HP composed of the partial vector corresponding to the antenna for transmitting the signal in the downlink channel transmission matrix H. A precoding matrix composed of a matrix 1 to m column vector and a partial precoding matrix to be determined. For the application scenario shown in Figure 1, m is 1. Specifically, ( ipf „ Ρ = ]^ ^Η , where 2 is a 4x4 matrix, which is a 1 x4 matrix, taking the first column q, q and c to form a precoding matrix W, ie

W=[q c].

In another embodiment, the second determining means 603 determines a partial precoding matrix c by maximizing the value of the smallest one of the singular values obtained by performing (Ma) matrix singular value decomposition, wherein W is based on the downlink a matrix composed of the partial vectors corresponding to the m antennas for transmitting signals in the channel transmission matrix ΗΡ, the first to m-column vectors of the right-hand singular matrix obtained by matrix singular value decomposition and the partial precoding matrix to be determined Form a precoding matrix. For the application scenario shown in Figure 1, m is 1.

In another embodiment, the second determining means 603 determines the partial precoding matrix by maximizing the value of the smallest element of the triangular matrix diagonal elements obtained by performing QR decomposition (H), wherein W is The conjugate transposed first to m-column vectors of the orthogonal matrix obtained by QR decomposition based on the conjugate transpose of the matrix ΗΡ of the matrix 对应 corresponding to the m antennas for transmitting signals in the downlink channel transmission matrix Η The partial precoding matrix to be determined constitutes a precoding matrix. For the application scenario shown in Figure 1, m has a value of 1.

It should be noted that the manner in which the second determining means 603 determines the partial precoding matrix indicator according to the principle of maximizing the channel transmission capacity has various manifestations, and is not limited to the matrix (H.). (H.) described above. "The determinant is the largest, or the matrix (H.) is the largest with the smallest singular value after singular value decomposition, or the matrix with the smallest of the diagonal elements of the triangle matrix after QR decomposition; for example Can be maximized Signal dry-to-noise ratio and other forms of expression are determined.

Figure 7 is a block diagram showing the structure of an apparatus 700 for acquiring downlink channel state information for a plurality of antenna user terminals in a base station of a time division multiplexed wireless communication network in accordance with an embodiment of the present invention. The acquisition device 700 includes a second receiving device 701, a third determining device 702, a matrix decomposing device 703, and a precoding device 704. The operation of the acquisition device 700 in the base station 10 will be described in detail below with reference to FIG.

First, the second receiving device 701 receives the uplink reference signal from the user terminal 20, and receives a partial precoding matrix indicator corresponding to at least one antenna of the user terminal 20 for receiving only the signal and not for transmitting the uplink reference signal.

Then, the third determining means 702 determines a transmission matrix of the partial downlink channel corresponding to the antenna of the user terminal 20 for transmitting the uplink reference signal according to the received uplink reference signal.

Alternatively, after obtaining the channel state information of the downlink channel between the user terminal 10 and the user terminal 10, the obtaining means 700 may pre-code the signal to be sent to the user terminal 20 according to the channel state information.

In one embodiment, the matrix decomposition device 703 performs matrix singular value decomposition on the transmission matrix HP of the partial downlink channel to obtain the first to m-column vectors of the right-hand side singular matrix; or the conjugate of the transmission matrix HP of the partial downlink channel The transposed matrix performs QR decomposition to obtain the first to m column vectors of the conjugate transposed matrix of the decomposed orthogonal matrix, where m is the number of antennas used for transmitting signals in the user terminal 20, as shown in FIG. Application scenario, m=l; For the application scenario shown in Figure 4, m=2.

Next, the precoding apparatus 704 forms a precoding matrix W to be transmitted to the user terminal 20 by using the first to m column vector and the partial precoding matrix c indicated by the partial precoding matrix indicator received by the second receiving device 701. Precoded. For the application scenario shown in Figure 1, the partial precoding matrix c corresponds to a portion of the downlink channel between the antennas 11, 12, 13 and 14 to the antenna 22, and c is a 4x1 matrix. For the application scenario shown in Figure 4, the partial precoding matrix c corresponds to a portion of the downlink channels between the antennas 11, 12, 13 and 14 to the antennas 23 and 24, and c is a 4x2 matrix.

FIG. 8 shows the time division multiplexing wireless communication system shown in FIG. 1 as an LTE-A wireless communication Schematic diagram of channel capacity simulation under different channel state information feedback schemes when the system is used. Where the abscissa represents the signal-to-noise ratio (in dB), the ordinate represents the channel capacity (in bps/Hz), and the asterisk "*" indicates the use of a complete upstream reference signal feedback mechanism, rectangular

"□" indicates a feedback mechanism using a mixture of partial uplink reference signals and partial precoding matrix indicators of the present invention, the left triangle "0" indicates a full precoding matrix indicator feedback mechanism, and the right triangle '{>, indicating only partial uplink Reference signal feedback mechanism. As can be seen from FIG. 8, the channel capacity of the full uplink reference signal feedback mechanism is the largest, and the channel capacity of the feedback mechanism of the partial uplink reference signal and the partial precoding matrix indicator of the present invention is second, which is better. A full precoding matrix indicator feedback mechanism and a partial uplink reference signal feedback mechanism are employed. The simulation parameter values used in Fig. 8 are shown in Table 1.

Table 1

The specific embodiments of the present invention have been described above. It should be understood that the present invention It is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the appended claims. The technical solution of the present invention can be implemented by software or hardware.

Claims

Claim

A method for a base station to acquire downlink channel state information to a user terminal in a multi-antenna user terminal of a time division multiplexing wireless communication network, wherein the number of antennas used by the user terminal to transmit an uplink reference signal The antenna is smaller than the number of antennas for receiving signals, and the antenna for receiving signals includes an antenna for transmitting an uplink reference signal, and the method includes the following steps:

- transmitting an uplink reference signal to the base station; and

- transmitting a partial precoding matrix indicator corresponding to at least one antenna for receiving signals only for transmitting the uplink reference signal to the base station.

2. The method of claim 1 further comprising the steps of:

A. receiving a downlink reference signal from the base station;

B. determining a downlink channel transmission matrix according to the downlink reference signal;

C. determining the partial precoding matrix indicator based on the downlink channel transmission matrix and the principle of maximizing channel transmission capacity.

3. The method according to claim 2, wherein said step C comprises the step of: - determining said partial precoding matrix by maximizing a determinant value of (H) - (H · ", wherein W is a matrix consisting of a matrix of the partial vectors corresponding to the m antennas for transmitting signals in the downlink channel transmission matrix, and a first to _m- column vector of the right-hand singular matrix obtained by matrix singular value decomposition and a partial precoding matrix to be determined A precoding matrix is formed, and Η is the downlink channel transmission matrix.

4. The method according to claim 2, wherein said step C comprises the step of: - determining said partial precoding matrix by maximizing a determinant value of (H.). (H.) ^w , wherein 1st to m of the conjugate transposed matrix of the orthogonal matrix obtained by QR decomposition of the conjugate transposed matrix of the matrix of the partial vector corresponding to the m antennas for transmitting signals in the downlink channel transmission matrix A precoding matrix composed of a column vector and a partial precoding matrix to be determined, and Η is the downlink channel transmission matrix.

5. The method according to claim 2, wherein the step C comprises the following steps: Determining the partial precoding matrix by maximizing the value of the smallest one of the singular values obtained by performing matrix singular value decomposition (H. W), wherein W is used according to the downlink channel transmission matrix The matrix of the partial vector corresponding to the m antennas of the transmitted signal is subjected to matrix singular value decomposition, and the first to mth column vectors of the right 酉 singular matrix are combined with the partial precoding matrix to be determined to form a precoding matrix. The downlink channel transmission matrix.

6. The method according to claim 2, wherein the step C comprises the following steps:

Determining the partial precoding matrix by maximizing the value of the smallest of the triangular matrix diagonal elements obtained by QR decomposition of the conjugate transposed matrix of (H.), where w is according to the downlink The first to m-column vectors of the conjugate transposed matrix of the orthogonal matrix obtained by QR decomposition of the conjugate transposed matrix of the matrix of the partial vector corresponding to the m antennas for transmitting signals in the channel transmission matrix The determined partial precoding matrix constitutes a precoding matrix, and Η is the downlink channel transmission matrix.

A method for acquiring downlink channel state information of a plurality of antenna user terminals in a base station of a time division multiplexed wireless communication network, wherein the number of antennas used by the user terminal to transmit an uplink reference signal is smaller than for receiving The number of antennas of the signal, and the antenna for receiving the signal includes an antenna for transmitting an uplink reference signal, and the method includes the following steps:

Receiving an uplink reference signal from the user terminal, and receiving a partial precoding matrix indicator corresponding to at least one antenna of the user terminal for receiving only signals and not for transmitting an uplink reference signal;

And determining, according to the received uplink reference signal, a transmission matrix of a part of the downlink channel corresponding to the antenna for transmitting the uplink reference signal from the base station to the user terminal.

8. The method according to claim 7, further comprising the steps of:

- performing matrix singular value decomposition on the transmission matrix of the partial downlink channel to obtain the first to m column vectors of the right 酉 singular matrix; or performing QR decomposition on the conjugate transposed matrix of the transmission matrix of the partial downlink channel Obtaining a first to m column vector of the conjugate transposed matrix of the decomposed orthogonal matrix, where m is used to transmit a signal in the user terminal The number of antennas.

- precoding using the first to m column vectors and the number indicated by the partial precoding matrix indicator.

9. A device for a base station to acquire downlink channel state information to a user terminal in a multi-antenna user terminal of a time division multiplexed wireless communication network, wherein the number of antennas used by the user terminal to transmit an uplink reference signal The antenna is smaller than the number of antennas for receiving signals, and the antenna for receiving signals includes an antenna for transmitting an uplink reference signal, and the apparatus includes:

a first transmitting device, configured to send an uplink reference signal to the base station; and send a partial precoding matrix indicator corresponding to at least one antenna that is only used to receive the signal and not used to transmit the uplink reference signal to the base station.

10. The apparatus according to claim 9, further comprising:

a first receiving device, configured to receive a downlink reference signal from the base station, where the first determining device is configured to determine a downlink channel transmission matrix according to the downlink reference signal;

And second determining means, configured to determine the partial precoding matrix indicator according to the downlink channel transmission matrix and the principle of maximizing channel transmission capacity.

11. Apparatus according to claim 10, wherein said second determining means is for:

Determining the partial precoding matrix by maximizing the determinant value of (H.). H is the downlink channel transmission matrix, and W is the downlink channel transmission matrix and the signal used for transmitting a matrix consisting of the partial vectors corresponding to the _m antennas, and a precoding matrix composed of the first to mth column vectors of the right 酉 singular matrix obtained by the matrix singular value decomposition and a partial precoding matrix to be determined; or W is the downlink The first to m-column vectors of the conjugate transposed matrix of the orthogonal matrix obtained by QR decomposition of the conjugate transposed matrix of the matrix of the partial vector corresponding to the _m antennas for transmitting signals in the channel transmission matrix A precoding matrix composed of determined partial precoding matrices.

12. The apparatus according to claim 10, wherein the second determining means is configured to: Determining the partial precoding matrix by maximizing the value of the smallest one of the singular values obtained by performing matrix singular value decomposition (H. W), wherein W is used according to the downlink channel transmission matrix The matrix of the partial vector corresponding to the m antennas of the transmitted signal is subjected to matrix singular value decomposition, and the first to mth column vectors of the right 酉 singular matrix are combined with the partial precoding matrix to be determined to form a precoding matrix. The downlink channel transmission matrix.

13. The apparatus according to claim 10, wherein the second determining means is for:

Determining the partial precoding matrix by maximizing the value of the smallest of the triangular matrix diagonal elements obtained by QR decomposition of the conjugate transposed matrix of (H), wherein w is according to the downlink channel The conjugate transposed matrix of the matrix composed of the partial vectors corresponding to the m antennas for transmitting signals in the transmission matrix is QR-decomposed to obtain the first to m-column vectors of the conjugate transposed matrix of the decomposed orthogonal matrix The partial precoding matrix to be determined constitutes a precoding matrix, and Η is the downlink channel transmission matrix.

An apparatus for acquiring downlink channel state information of a plurality of antenna user terminals in a base station of a time division multiplexing wireless communication network, wherein the number of antennas used by the user terminal to transmit an uplink reference signal is smaller than The number of antennas that receive the signal, and the antenna for receiving the signal includes an antenna for transmitting an uplink reference signal, and the acquiring device includes

a second receiving device, configured to receive an uplink reference signal from the user terminal, and receive a partial precoding matrix indicator corresponding to at least one antenna in the user terminal that is only used to receive signals and not used to send an uplink reference signal ;

The third determining means is configured to determine, according to the received uplink reference signal, a transmission matrix of a part of the downlink channels of the base station to the antenna of the user terminal for transmitting the uplink reference signal.

15. The obtaining device according to claim 14, further comprising:

a matrix decomposition device, configured to perform matrix singular value decomposition on a transmission matrix of the partial downlink channel to obtain a first to m column vector of a right side singular matrix; or a conjugate transpose of a transmission matrix of the partial downlink channel The matrix is QR decomposed to obtain the decomposed positive The first to m-column vectors of the conjugate transposed matrix of the matrices, where m is the number of antennas used to transmit signals in the user terminal.

a precoding apparatus, configured to form, by the first to m column vectors, a partial precoding matrix indicated by the partial precoding matrix indicator into a precoding matrix, to be sent to the user terminal by using the precoding matrix The signal is precoded.