WO2008125021A1 - Method, system and equipments for precoding in time division dual system - Google Patents

Abstract

A method for precoding in time division dual (TDD) system is presented. This method includes following steps: the base station looks over uplink resources and switches the codebook precoding mode to the non-codebook precoding mode when there are uplink resources which can transmit reference symbols; the terminal switches the codebook precoding mode to the non-codebook precoding mode; the base station and the terminal operate the non-codebook precoding. It is solved that TDD systems can not support both codebook and non-codebook precoding modes simultaneously. The present invention also provides a precoding system and equipments in TDD system.

Description

 Method, system and device for precoding in time division duplex system

 The present invention relates to the field of communications technologies, and in particular, to a method, system and apparatus for performing precoding in a time division duplex system. Background technique

 Multiple Input Multiple Output (MIMO) has become an effective method to improve the efficiency of wireless transmission spectrum. Usually, the receiving end can easily obtain channel information through channel estimation. However, if the transmitting side also knows the channel information, the channel capacity can be further improved. The precoding technique is a technique for pre-processing a transmitted signal by using channel information at a transmitting end. The precoding is to multiply a data stream to be transmitted by a precoding matrix to map and transmit the data stream.

 In the Long Term Evolution (LTE) system, spatial precoding (pre-coding) technology can improve system performance and reduce the complexity of user equipment (UE). Pre-coding can be classified into a codebook precoding operation and a non-codebook precoding operation depending on whether or not a finite number of pre-coding matrices are employed. In order to ensure the commonality of Frequency Division Duplex (FDD) system and Time Division Duplex (TDD) system, TDD system is required to support Codebook precoding operation. Meanwhile, in order to utilize the channel symmetry of TDD system, Non-Codebook can also be used. Encoding operation.

 The non-Codebook precoding operation means that the base station side obtains the uplink channel information by receiving the uplink signal, and obtains the spatial channel information in the downlink direction by using the channel symmetry of the TDD system, thereby obtaining the precoding matrix by using the spatial channel information. And perform precoding operations.

For example, for a TDD system with M transmit antennas on one base station side and N receive antennas on the terminal side, the base station can obtain the uplink spatial channel matrix H ⁱ by receiving the uplink signal, and then use the uplink and downlink channels of the TDD system. The reciprocity of the downlink spatial channel matrix ^{Η∞ =} ( ^ΗίΛ ) ⁷ ' can be obtained directly from the uplink spatial channel matrix. Where H"4 dimension is M x N, H dimension is Ν χ Μ. Singular value decomposition (SVD) is performed on the downlink channel matrix H ^D to obtain the lower ^" direction Precoding matrix v _fl :

H ^Di = VAV ^H

Is a B (B ^{≤ min} ( ^M , W) ) non-zero eigenvalues. Note that we assume that the eigenvalues of Λ are in descending order. ^V s is a non-zero eigenvalue corresponding to the eigenvector, which is an orthogonal matrix of ( ^>< ) order.

 When performing a Non-Codebook precoding operation, both the data symbols and the reference symbols are required to be precoded, that is,

X = V _B S

Y = V _B D

 Where S is the data symbol to be transmitted, and the dimension is BX 1; X is the data signal transmitted on the M antennas after precoding, and the dimension is M x 1; D is the reference symbol to be sent, and the dimension is BX 1 ; Y is the reference signal transmitted on the M antennas after precoding; V is the precoding matrix, and the dimension is M x B.

For Codebook precoding operations, the system needs to pre-determine a set of precoding matrices called codebooks. For example, when M=4, B=2, you can use the following method to construct a codebook: -

 . +

0 -^exp(y ₂ )

 Thus, there are 16 precoding matrices. Specifically, each precoding matrix can be numbered, and the precoding matrix after numbering is denoted as V(i), i=0...15.

After receiving the downlink common reference symbols, the terminal can obtain the downlink spatial channel matrix, and select a suitable precoding matrix ^v in the codebook by some criteria. For example, the receiving end uses The minimum mean square error linear detection (MMSE) algorithm selects the precoding matrix ^v a . When using different precoding matrices, the mean square error of the estimated signal is:

MSE{i) = tracJ + V( * (H ^OL )* R _NN - ^ ν(θ '], i =.... 15 where I is the unit matrix; 0' is the conjugate transpose of the matrix; R _nn is the noise Variance matrix.

 Then the sequence number of the precoding matrix V is:

 Index = arg min (MSE ( ))

 ,·=0··· 15

The terminal feeds back the sequence number to the base station, and the base station uses the sequence number to obtain a corresponding precoding matrix ^v fl = ^v « (index) in the codebook.

 When performing Codebook precoding operations, only the data symbols are precoded, and the reference symbols are not precoded, ie:

X = V _B S

 Y = D

Where S is the data symbol to be transmitted, and the dimension is BXI; X is the data signal transmitted on the M antennas after precoding, and the dimension is MX 1; D and Y are reference symbols transmitted on the M antennas, The number is M x 1 ; ^v s is the precoding matrix, and the dimension is M x B.

 It can be seen that the non-codebook precoding operation for the TDD system can greatly save the required feedback signaling overhead, and the calculation amount is placed at the base station side to reduce the burden on the terminal, but the base station needs to obtain the channel matrix from the transmission of the uplink reference symbol. Therefore, the terminal is required to have two antennas transmitting capability or capable of performing two antenna switching transmissions, and transmitting uplink data symbols and/or sounding reference symbols in a frequency band of downlink precoding transmission; the Codebook precoding operation does not need to be uplinked The channel matrix is obtained in the transmission of the reference symbol. The Codebook precoding operation itself does not require the terminal to transmit, but the calculation amount is placed in the terminal, and the base station obtains the corresponding precoding matrix from the Codebook through the precoding matrix sequence number fed back by the terminal.

However, the current TDD system cannot support both the Non-codebook and the Codebook precoding operations, resulting in wasted resources and increased overhead. Summary of the invention

 The method, system and device for performing precoding in the time division duplex system provided by the embodiment of the present invention are used to solve the problem that the two precoding operations of the Non-codebook and the Codebook cannot be simultaneously supported in the TDD system existing in the prior art.

 A method for precoding in a time division duplex system includes:

 The base station checks the current uplink resource, and when there is the uplink resource capable of transmitting the uplink reference symbol, the code precoding mode is switched to the non-codebook precoding mode, and the terminal switches the codebook precoding mode to the non-codebook precoding. In a manner, the base station and the terminal perform a non-codebook precoding operation.

 A method for precoding in a time division duplex system includes:

 The base station checks the current uplink resource, and when there is no uplink resource capable of transmitting the uplink reference symbol, the non-codebook precoding mode is switched to the codebook precoding mode, and the terminal switches the non-codebook precoding mode to the codebook precoding. In a manner, the base station and the terminal perform a codebook precoding operation.

 A system for precoding in a time division duplex system includes:

 The base station is configured to view the current uplink resource, and when there is the uplink resource capable of transmitting the uplink reference symbol, switch the codebook precoding mode to the non-codebook precoding mode to perform the non-codebook precoding operation; The non-codebook precoding operation is performed by switching the codebook precoding mode to the non-codebook precoding mode.

 A system for precoding in a time division duplex system includes:

 a base station, configured to view a current uplink resource, and when there is no uplink resource capable of transmitting an uplink reference symbol, switch the non-codebook precoding mode to a codebook precoding mode to perform a codebook precoding operation; The non-codebook precoding method is switched to the codebook precoding mode, and the codebook precoding operation is performed.

 A base station includes:

a configuration module, configured to view a current uplink resource, and switch the codebook precoding mode to a non-codebook precoding mode when the uplink resource that can send the uplink reference symbol is used; And a processing module, configured to perform a non-codebook precoding operation after the configuration module switches the codebook precoding mode to the non-codebook precoding mode.

 A terminal includes:

 The switching module is configured to switch the codebook precoding mode to the non-codebook precoding mode after receiving the control signaling including the non-codebook from the base station;

 And an operation module, configured to perform a non-codebook precoding operation after the switching module switches the codebook precoding mode to the non-codebook precoding mode.

 The operation module further includes:

 And a channel estimation module, configured to perform channel estimation on the received pre-coded parameter symbols from the base station, obtain an equivalent channel matrix, and perform data demodulation.

 A base station includes:

 a configuration module, configured to view a current uplink resource, and switch the non-codebook precoding mode to a codebook precoding mode when the uplink resource that cannot send the uplink reference symbol is not used;

 And a processing module, configured to perform a codebook precoding operation after the configuration module switches the non-codebook precoding mode to the codebook precoding mode.

 A terminal includes:

 a switching module, configured to: after receiving the control signaling including the codebook from the base station, switch the non-codebook precoding mode to the codebook precoding mode;

 And an operation module, configured to perform a codebook precoding operation after the switching module switches the non-codebook precoding mode to the codebook precoding mode.

 The terminal further includes:

 a selection module, configured to switch the non-codebook precoding mode to the codebook precoding mode, and after receiving the common parameter symbol from the base station, select an appropriate preamble from the codebook And an encoding matrix, which sends the precoding matrix sequence number to the base station.

In the embodiment of the present invention, the base station checks the current uplink resource, and when there is the uplink resource capable of transmitting the uplink reference symbol, the base station switches the precoding mode to the non-codebook precoding mode, and sends the precoding mode to the terminal. Sending the control signaling including the non-codebook, after receiving the control signaling, the terminal switches the precoding mode to the non-codebook precoding mode; when there is no uplink resource capable of transmitting the uplink reference symbol The base station switches the precoding mode to the codebook precoding mode, and sends control signaling including the codebook to the terminal, and after receiving the control signaling, the terminal switches the precoding mode to the codebook. Precoding method. Therefore, the TDD system can support two precoding operations at the same time, saving resources and reducing overhead. DRAWINGS

 1 is a schematic structural diagram of a system for switching a Codebook precoding method to a Non-codebook precoding method in a time division duplex system according to an embodiment of the present invention;

 2A is a schematic diagram of a base station composition of a codebook precoding method switched to a Non-codebook precoding mode in a time division duplex system according to an embodiment of the present invention;

 2B is a schematic diagram of a terminal composition of a codebook precoding mode switched to a Non-codebook precoding mode in a time division duplex system according to an embodiment of the present invention;

 3 is a schematic diagram of a system composition of a Non-codebook precoding method switched to a Codebook precoding mode in a time division duplex system according to an embodiment of the present invention;

 4A is a schematic diagram of a base station composition of a Non-codebook precoding method switched to a Codebook precoding mode in a time division duplex system according to an embodiment of the present invention;

 4B is a schematic diagram of a terminal composition of a Non-codebook precoding method switched to a Codebook precoding mode in a time division duplex system according to an embodiment of the present invention;

 5 is a schematic flowchart of a method for switching a Codebook precoding method to a Non-codebook precoding method in a time division duplex system according to an embodiment of the present invention;

 6 is a schematic flowchart of a method for switching a Non-codebook precoding method to a Codebook precoding method in a time division duplex system according to an embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for performing a Non-codebook precoding operation by a base station according to an embodiment of the present invention; FIG. 8 is a schematic flowchart of a method for performing a Codebook precoding operation by a base station according to an embodiment of the present invention. detailed description

 The present invention provides a solution to the problem that the two precoding operations of the Non-codebook and the Codebook cannot be simultaneously supported in the TDD system. Specifically, the base station views the current uplink resource, and when there is an uplink resource capable of transmitting the uplink reference symbol. The base station switches the Codebook precoding mode to the Non-codebook precoding mode, and sends control signaling including the Non-codebook to the terminal. After receiving the control signaling, the terminal switches the Codebook precoding mode to the Non-codebook pre The coding mode is: when there is no uplink resource capable of transmitting the uplink reference symbol, the base station switches the Non-codebook precoding mode to the Codebook precoding mode, and sends control signaling including the Codebook to the terminal, after receiving the control signaling, the terminal receives the control signaling. The precoding method is switched to the Codebook precoding mode, thereby solving the above problem.

 As shown in FIG. 1, the system in which the Codebook precoding mode is switched to the Non-codebook precoding mode in the time division duplex system in the embodiment of the present invention includes: a base station 10 and a terminal 20.

 The base station 10 is connected to the terminal 20 and configured to view the current uplink resource. When there is an uplink resource capable of transmitting the uplink reference symbol, the codebook precoding mode is switched to the Non-codebook precoding mode, and the terminal is sent to include the Non-codebook. Control signaling, and perform non-codebook precoding operations. The terminal 20 is configured to switch the Codebook precoding mode to the Non-codebook precoding mode after receiving the control signaling including the Non-codebook from the base station 10, and perform a Non-codebook precoding operation.

 The base station 10 can view the current uplink resource according to the setting, and can also view the current uplink resource when needed.

 As shown in FIG. 2A, the base station in which the Codebook precoding mode is switched to the Non-codebook precoding mode in the time division duplex system according to the embodiment of the present invention includes: a configuration module 100 and a processing module 110.

The configuration module 100 is connected to the processing module 110 and configured to view the current uplink resource. When there is an uplink resource capable of transmitting the uplink reference symbol, the Codebook precoding mode is switched to Non-codebook precoding method.

 The processing module 110 is connected to the configuration module 100, and is configured to perform a Non-codebook precoding operation after the configuration module 100 switches the Codebook precoding mode to the Non-codebook precoding mode.

 The processing module 110 may further include: an obtaining module 1100 and a pre-encoding module 1110. The obtaining module 1100 is connected to the precoding module 1110, and is configured to check whether the channel matrix can be obtained from the transmission of the uplink reference symbol after the configuration module 100 switches the Codebook precoding mode to the Non-codebook precoding mode. If yes, The channel matrix is acquired, otherwise, the terminal 20 is notified to transmit the uplink reference symbol and the channel matrix is obtained from the uplink reference symbol.

 The precoding module 1110 is configured to determine a precoding matrix according to the channel matrix acquired by the obtaining module 1100, and perform precoding operations on the data symbols and the parameter symbols demodulating the data symbols according to the precoding matrix.

 The base station in the time division duplex system in which the codebook precoding mode is switched to the Non-codebook precoding mode may further include: a first sending module 120.

 The first sending module 120 is connected to the configuration module 100, and is configured to send the control signaling including the Non-codebook to the terminal 20 after the configuration module 100 switches the Codebook precoding mode to the Non-codebook precoding mode.

 The base station in the time division duplex system in which the codebook precoding mode is switched to the Non-codebook precoding mode may further include: a second sending module 130.

 The second sending module 130 is connected to the processing module 110 and configured to send the pre-coded parameter symbols and data symbols in the processing module 110 to the terminal 20.

 As shown in FIG. 2B, the terminal that switches the Codebook precoding mode to the Non-codebook precoding mode in the time division duplex system according to the embodiment of the present invention includes: a switching module 200 and an operation module 210.

The switching module 200 is connected to the operation module 210, and is configured to switch the Codebook precoding mode to the Non-codebook precoding mode after receiving the control signaling including the Non-codebook from the base station 10. The operation module 210 is configured to The switching module 200 cuts the Codebook precoding method. After switching to the Non-codebook precoding method, the Non-codebook precoding operation is performed.

 The operation module 210 further includes:

 The channel estimation module 2100 is configured to perform channel estimation on the received pre-coded parameter symbols from the base station 10, obtain an equivalent channel matrix, and perform data demodulation.

 As shown in FIG. 3, the system for switching the Non-codebook precoding mode to the Codebook precoding mode in the time division duplex system of the embodiment of the invention includes: a base station 30 and a terminal 40.

 The base station 30 is connected to the terminal 40 and configured to view the current uplink resource. When there is no uplink resource capable of transmitting the uplink reference symbol, the non-codebook precoding mode is switched to the Codebook precoding mode, and the control including the Codebook is sent to the terminal. Signaling and performing Codebook precoding operations. After receiving the control signaling including the Codebook from the base station 30, the terminal 40 switches the Non-codebook precoding method to the Codebook precoding mode and performs the Codebook precoding operation.

 The base station 30 can determine whether there is an uplink resource for transmitting the uplink reference symbol according to the setting, and can also determine whether there is an uplink resource for transmitting the uplink reference symbol when needed.

 As shown in FIG. 4A, a base station in which a Non-codebook precoding method is switched to a Codebook precoding mode in a time division duplex system according to an embodiment of the present invention includes: a configuration module 300 and a processing module 310.

 The configuration module 300 is connected to the processing module 310 and configured to view the current uplink resource. When there is no uplink resource capable of transmitting the uplink reference symbol, the Non-codebook precoding mode is switched to the Codebook precoding mode. The processing module 310 is configured to perform a Codebook precoding operation after the configuration module 300 switches the Non-codebook precoding mode to the Codebook precoding mode.

 The processing module 310 may further include: a second sending module 3100 and a pre-encoding module 3110. The second sending module 3100 is configured to periodically send the common reference symbol that is not precoded to the terminal 40 after the configuration module 300 switches the Non-codebook precoding mode to the Codebook precoding mode.

The precoding module 3110 is configured to determine a corresponding precoding matrix according to the received precoding mode sequence number from the terminal 40, and perform precoding operation on the data symbols and the parameter symbols of the demodulated data symbols. The precoded parameter symbols are transmitted to the terminal 40.

 The base station that switches the Non-codebook precoding mode to the Codebook precoding mode in the time division duplex system according to the embodiment of the present invention may further include: a first sending module 320.

 The first sending module 320 is connected to the configuration module 300, and is configured to send the control signaling including the Codebook to the terminal 40 after the configuration module 300 switches the Non-codebook precoding mode to the Codebook precoding mode.

 The base station in the time division duplex system in which the Non-codebook precoding method is switched to the Codebook precoding mode may further include: a third sending module 330.

 The third sending module 330 is connected to the processing module 310 and configured to send the pre-coded parameter symbols and data symbols in the processing module 310 to the terminal 40.

 As shown in FIG. 4B, the terminal in the time division duplex system in which the Non-codebook precoding method is switched to the Codebook precoding mode includes: a switching module 400 and an operation module 410.

 The switching module 400 is connected to the operation module 410, and is configured to switch the Non-codebook precoding mode to the Codebook precoding mode after receiving the control signaling including the Codebook from the base station 30; and the operation module 410 is configured to be in the switching module. After switching the Non-codebook precoding method to the Codebook precoding mode, the Codebook precoding operation is performed.

 The operation module 410 further includes:

 The channel estimation module 4100 is configured to perform channel estimation on the received precoded parameter symbols from the base station 30, obtain an equivalent channel matrix, and perform data demodulation.

 The terminal that switches the Non-codebook precoding mode to the Codebook precoding mode in the time division duplex system of the embodiment of the present invention further includes: a selection module 420.

 The selection module 420 is connected to the switching module 400 for switching the Non-codebook precoding mode to the Codebook precoding mode after the switching module 400, and after receiving the common parameter symbol from the base station 30, selecting an appropriate precoding from the Codebook. The matrix transmits the precoding matrix sequence number to the base station 30.

In order to save resources, reduce overhead, and obtain better system performance, when there is channel information, Codebook is switched to Non-codebook:.

 As shown in FIG. 5, the method for switching the Codebook precoding mode to the Non-codebook precoding mode in the time division duplex system according to the embodiment of the present invention includes the following steps:

 Step 500: The base station checks the current uplink resource. When there is an uplink resource capable of transmitting the uplink reference symbol, the codebook precoding mode is switched to the Non-codebook precoding mode, and the control signaling including the Non-codebook is sent to the terminal.

 Step 501: The base station performs a Non-codebook precoding operation.

 Step 502: After receiving the control signaling from the base station, the terminal switches the Codebook precoding mode to the Non-codebook precoding mode to perform the Non-codebook precoding operation.

 In step 500, the base station may view the current uplink resource according to the setting, and may also view the current uplink resource when needed.

 When the terminal is unable to send the uplink reference symbol according to its capability, it needs to select the Codebook method and notify the base station through the uplink control signaling, and the Codebook needs to be switched to the Non-codebook.

 As shown in FIG. 6, the method for switching the Non-codebook precoding mode to the Codebook precoding mode in the time division duplex system according to the embodiment of the present invention includes the following steps:

 Step 600: The base station checks the current uplink resource, and when there is no uplink resource capable of transmitting the uplink reference symbol, the Non-codebook precoding mode is switched to the Codebook precoding mode, and the control signaling including the Codebook is sent to the terminal.

 Step 601: After receiving the control signaling from the base station, the terminal switches the Non-codebook precoding mode to the Codebook precoding mode.

 Step 602: The base station and the terminal perform a Codebook precoding operation.

 In step 600, the base station can view the current uplink resource according to the setting, and can also view the current uplink resource when needed.

 In order to facilitate the understanding and implementation of the present invention by those skilled in the art, the specific embodiments of the present invention will be further described.

As shown in FIG. 7, a method for performing a Non-codebook precoding operation by a base station in an embodiment of the present invention Includes the following steps:

 Step 700: Set a precoding mode of the base station and the terminal to a Codebook precoding mode. Step 701: The base station determines whether there is an uplink resource that can send an uplink reference symbol in the current uplink resource. If yes, step 702 is performed; otherwise, the flow is skipped.

 Step 702: The base station switches the Codebook precoding mode to the Non-codebook precoding mode, and sends control signaling including the Non-codebook to the terminal.

 Step 703: After receiving the control signaling from the base station including the Non-codebook, the terminal will

The Codebook precoding method is switched to the Non-codebook precoding method.

 Step 704: The base station periodically sends a common reference symbol that is not precoded.

 Step 705: The base station checks whether the channel matrix can be obtained from the transmission of the uplink reference symbol, and if yes, performs step 706; otherwise, performs step 707.

 Step 706: The base station acquires a channel matrix from the transmission of the uplink reference symbol, and performs step 708. Step 707: The base station notifies the terminal to send an uplink reference symbol, and obtains a channel matrix from the uplink reference symbol.

 Step 708: The base station determines the precoding matrix by using the obtained channel matrix, performs precoding operation on the data symbol and the reference symbol demodulating the data symbol, and sends the precoded reference symbol and the data symbol to the terminal.

 Step 709: The terminal performs channel estimation according to the received reference symbols, obtains an equivalent channel matrix, and performs data demodulation.

 As shown in FIG. 8, the method for performing a Codebook precoding operation by a base station in the embodiment of the present invention includes the following steps:

 Step 800: Set a precoding mode of the base station and the terminal to a Non-codebook precoding mode. Step 801: The base station determines whether there is an uplink resource that can send an uplink reference symbol in the current uplink resource, and if yes, the flow is skipped; otherwise, step 802 is performed.

Step 802: The base station switches the Non-codebook precoding mode to the Codebook precoding mode, and sends control signaling including the Codebook to the terminal. Step 803: After receiving the control signaling of the Codebook from the base station, the terminal switches the Non-codebook precoding mode to the Codebook precoding mode.

 Step 804: The base station periodically sends a common reference symbol that is not precoded.

 Step 805: The terminal obtains a channel matrix according to the received common reference symbol from the base station, and selects a suitable precoding matrix from the Codebook, and sends the sequence number of the precoding matrix to the base station.

 Step 806: The base station determines a precoding matrix from the Codebook according to the received sequence number from the terminal, performs precoding operation on the data symbol and the reference symbol demodulating the data symbol, and sends the precoded reference symbol and the data symbol to the terminal. .

 Step 807: The terminal performs channel estimation according to the received reference symbols, obtains an equivalent channel matrix, and performs data demodulation.

 It can be seen from the foregoing embodiment that: in the embodiment of the present invention, the base station checks the current uplink resource, and when there is an uplink resource capable of transmitting the uplink reference symbol, the base station switches the Codebook precoding mode to the Non-codebook precoding mode, and Sending control signaling including a Non-codebook to the terminal, after receiving the control signaling, the terminal switches the Codebook precoding mode to the Non-codebook precoding mode; when there is no uplink resource capable of transmitting the uplink reference symbol, the base station will The non-codebook precoding mode is switched to the Codebook precoding mode, and the control signaling including the Codebook is sent to the terminal. After receiving the control signaling, the terminal switches the precoding mode to the Codebook precoding mode, thereby solving the above problem. . Therefore, the TDD system can support two precoding operations at the same time, saving resources and reducing overhead. The spirit and scope of the Ming. Thus, it is intended that the present invention cover the modifications and variations of the inventions

Claims

Rights request  A method for performing precoding in a time division duplex system, the method comprising: the base station viewing a current uplink resource,  When there is the uplink resource capable of transmitting the uplink reference symbol, the code precoding mode is switched to the non-codebook precoding mode, and the terminal switches the codebook precoding mode to the non-codebook precoding mode.  The base station and the terminal perform a non-codebook precoding operation.  The method according to claim 1, wherein the base station further comprises: after switching the codebook precoding mode to the non-codebook precoding mode:  Transmitting control signaling including the non-codebook to the terminal;  After receiving the control signaling, the terminal switches the codebook precoding mode to the non-codebook precoding mode.  3. The method according to claim 1, wherein the step of performing a non-codebook precoding operation by the base station comprises:  Determining, by the base station, whether a channel matrix can be obtained from the transmission of the uplink reference symbol, and if yes, acquiring the channel matrix, otherwise, notifying the terminal to send the uplink reference symbol, and acquiring a channel matrix from the uplink reference symbol;  The base station determines a precoding matrix according to the channel matrix, and performs a precoding operation on the data symbols and the parameter symbols demodulating the data symbols according to the precoding matrix.  The method according to claim 3, wherein the base station performs the precoding operation, further comprising the steps: the base station sends the precoded parameter symbols and data symbols to the terminal;  The step of the terminal performing the non-codebook precoding operation includes:  The terminal performs channel estimation on the received parameter symbols, acquires an equivalent channel matrix, and performs data demodulation. A method for performing precoding in a time division duplex system, the method comprising: the base station viewing a current uplink resource, and precoding the non-codebook when the uplink resource capable of transmitting the uplink reference symbol is not available The mode is switched to the codebook precoding mode, and the terminal cuts the non-codebook precoding mode. In the codebook precoding mode, the base station and the terminal perform a codebook precoding operation.  The method according to claim 5, wherein the base station further comprises the following steps after switching the non-codebook precoding mode to the codebook precoding mode:  Transmitting control signaling including the codebook to the terminal;  After receiving the control signaling, the terminal switches the non-codebook precoding mode to the codebook precoding mode.  The method according to claim 5, wherein the step of performing a codebook precoding operation by the base station comprises: the base station transmitting, to the terminal period, a common reference symbol that is not precoded; and the base station according to the base station Receiving a precoding matrix sequence number from the terminal, determining a corresponding precoding matrix, performing a precoding operation on the data symbol and demodulating the parameter symbols of the data symbol; receiving the common parameter from the base station After the symbol, an appropriate precoding matrix is selected from the codebook, and the precoding matrix sequence number is sent to the base station.  The method according to claim 7, wherein the base station performs the precoding operation, further comprising the steps: the base station sends the precoded parameter symbols and data symbols to the terminal;  The step of performing a codebook precoding operation by the terminal includes: the terminal performing channel estimation on the received parameter symbol, acquiring an equivalent channel matrix, and performing data demodulation.  A system for performing precoding in a time division duplex system, the system comprising: a base station, configured to view a current uplink resource, and when there is the uplink resource capable of transmitting an uplink reference symbol, the codebook is used The precoding mode is switched to the non-codebook precoding mode to perform the non-codebook precoding operation. The terminal is configured to switch the codebook precoding mode to the non-codebook precoding mode to perform the non-codebook precoding operation.  The system of claim 9, wherein the base station comprises:  a configuration module, configured to view the current uplink resource, and when the uplink resource capable of transmitting the uplink reference symbol is used, switch the codebook precoding mode to the non-codebook precoding mode; a processing module, configured to switch the codebook precoding mode to a non-codebook precoding side in the configuration module After the formula, the non-codebook precoding operation is performed;  a first sending module, configured to: after the configuration module switches the codebook precoding mode to the non-codebook precoding mode, send, to the terminal, control signaling that includes the non-codebook;  The terminal includes:  The switching module is configured to switch the codebook precoding mode to the non-codebook precoding mode, and after receiving the control signaling sent by the first sending module, switch the codebook precoding mode to the non-codebook precoding mode ;  And an operation module, configured to perform a non-codebook precoding operation after the switching module switches the codebook precoding mode to the non-codebook precoding mode.  A system for performing precoding in a time division duplex system, the system comprising: a base station, configured to view a current uplink resource, where the uplink resource is not capable of transmitting an uplink reference symbol, The precoding method is switched to the codebook precoding mode to perform a codebook precoding operation. The terminal is configured to switch the non-codebook precoding mode to the codebook precoding mode to perform a codebook precoding operation.  The system of claim 11, wherein the base station comprises:  a configuration module, configured to view the current uplink resource, and switch the non-codebook precoding mode to the codebook precoding mode when the uplink resource that cannot send the uplink reference symbol is not used;  a processing module, configured to perform a codebook precoding operation after the configuration module switches the non-codebook precoding mode to the codebook precoding mode;  a sending module, configured to: after the configuration module switches the non-codebook precoding mode to the codebook precoding mode, send, to the terminal, control signaling that includes the codebook;  The terminal includes: a switching module, configured to switch the non-codebook precoding mode to the codebook precoding mode, and after receiving the control signaling sent by the sending module, switch the non-codebook precoding mode to the codebook precoding mode; And a module, configured to perform a codebook precoding operation after the switching module switches the non-codebook precoding mode to the codebook precoding mode. 13. A base station, the base station comprising:  a configuration module, configured to view a current uplink resource, where the codebook precoding mode is switched to a non-codebook precoding mode when there is an uplink resource capable of transmitting an uplink reference symbol;  And a processing module, configured to perform a non-codebook precoding operation after the configuration module switches the codebook precoding mode to the non-codebook precoding mode.  The base station according to claim 13, wherein the processing module includes: an obtaining module, configured to: after the configuration module switches the codebook precoding mode to the non-codebook precoding mode, Acquiring a channel matrix from the transmission of the uplink reference symbol, if yes, acquiring the channel matrix, otherwise, notifying the base station to send the uplink reference symbol, and acquiring a channel matrix from the uplink reference symbol;  And a precoding module, configured to determine a precoding matrix according to the channel matrix acquired by the acquiring module, and perform precoding operations on the data symbols and demodulating parameter symbols of the data symbols according to the precoding matrix.  The base station according to claim 13, wherein the base station comprises:  a first sending module, configured to: after the configuration module switches the codebook precoding mode to the non-codebook precoding mode, send, to the terminal, control signaling that includes the non-codebook;  And a second sending module, configured to send the parameter symbols and data symbols precoded by the precoding module to the terminal.  16. A terminal, the terminal comprising:  The switching module is configured to switch the codebook precoding mode to the non-codebook precoding mode after receiving the control signaling including the non-codebook from the base station;  And an operation module, configured to perform a non-codebook precoding operation after the switching module switches the codebook precoding mode to the non-codebook precoding mode. The terminal according to claim 16, wherein the operation module further comprises: a channel estimation module, configured to perform channel estimation on the received pre-coded parameter symbols from the base station, to obtain an equivalent Channel matrix, for data demodulation. 18. A base station, the base station comprising:  a configuration module, configured to view a current uplink resource, and switch the non-codebook precoding mode to a codebook precoding mode when the uplink resource that cannot send the uplink reference symbol is not used;  And a processing module, configured to perform a codebook precoding operation after the configuration module switches the non-codebook precoding mode to the codebook precoding mode.  The base station according to claim 18, wherein the base station further includes: a first sending module, configured to: after the configuration module switches the non-codebook precoding mode to the codebook precoding mode, Transmitting, by the terminal, control signaling including the codebook;  a second sending module, configured to: after the configuration module switches the non-codebook precoding mode to the codebook precoding mode, send a common reference symbol that is not precoded to the terminal period;  And a precoding module, configured to determine a corresponding precoding matrix according to the received precoding mode sequence number from the terminal, and perform precoding operation on the data symbol and the parameter symbol for demodulating the data symbol.  And a third sending module, configured to send the parameter symbols and data symbols precoded by the precoding module to the terminal.  20. A terminal, wherein the terminal comprises:  a switching module, configured to: after receiving the control signaling including the codebook from the base station, switch the non-codebook precoding mode to the codebook precoding mode;  And an operation module, configured to perform a codebook precoding operation after the switching module switches the non-codebook precoding mode to the codebook precoding mode.  The terminal according to claim 20, wherein the terminal further comprises: a selecting module, configured to switch, in the switching module, a non-codebook precoding mode to a codebook precoding mode, and receive the After the common parameter symbol of the base station, selecting a suitable precoding matrix from the codebook, and transmitting the precoding matrix sequence number to the base station;  The operation module further includes:  And a channel estimation module, configured to perform channel estimation on the received pre-coded parameter symbols from the base station, obtain an equivalent channel matrix, and perform data demodulation.