WO2013135084A1

WO2013135084A1 - Method, system and apparatus for precoding

Info

Publication number: WO2013135084A1
Application number: PCT/CN2012/087027
Authority: WO
Inventors: 贾明; 谭仕能; 陈磊
Original assignee: 华为技术有限公司
Priority date: 2012-03-16
Filing date: 2012-12-20
Publication date: 2013-09-19
Also published as: RU2015144478A; RU2632417C2; CN103312397A

Abstract

A precoding method comprises: implementing preprocessing of precoding for signals to be transmitted, the processing of the precoding increases power of the signals to be transmitted; selecting a power limitation algorithm according to a selection rule; limiting the power of the preprocessed signals according to the selected power limitation algorithm; generating precoded signals according to the signals with limited power. A transmitter, receiver and precoding system are disclosed in the embodiments of the present invention. In the present invention, at the same time the power limitation operation limits the transmission power, adverse effects on signal transmission caused by the power limitation operation can be reduced as much as possible.

Description

Precoding method, system and device

The present invention relates to the field of wireless communications, and in particular, to a precoding method, system, and apparatus. Background technique

MIMO (Multi-Input Multi-Output) technology can increase the capacity of wireless communication systems without increasing the transmission power. It has been widely used in LTE (Long Term Evolution) and WiMAX systems. Applications.

Precoding is an important branch of MIMO technology, which can be seen as a channel pre-equalization technique. Preprocessing the data according to the channel information at the transmitter allows the signal to obtain a better signal-to-noise ratio after passing through the channel, and thus obtain better performance at the receiver. Commonly used precoding algorithms include linear and nonlinear types. Linear precoding means that precoding processing can be realized by linear operations, and is usually implemented in comparison. Non-linear precoding refers to the existence of non-linear operations in the precoding process, which is complicated to implement, but usually achieves better performance.

Some nonlinear precoding algorithms, such as THP (Tomlinson-Harashima precoding), VP (Vector Perturbation), etc., some of which may cause the signal to be sent. As power increases, power limiting operations must be performed. In the current nonlinear precoding algorithm, the modulo operation is used for power limitation. However, in practical applications, the mode operation usually causes loss of signal performance due to factors such as estimation error and external interference.

The ZF-THP (Zero-Forcing Tomlinson-Harashima precoding) based on QR decomposition is taken as an example for illustration. 1 is a schematic diagram of a conventional ZF-THP-based transmitter side precoding method, and FIG. 2 is a schematic diagram of a receiver side precoding method corresponding to FIG. 1. The modulo operation is equivalent to adding a modulo offset to the signal so that the amplitude of the modulo signal does not exceed the target upper limit. But this modulo offset will inevitably interfere with the signal, even after receiving The machine side performs the same modulo recovery operation on the received signal as the modulo operation. Due to the feedback and the unsatisfactory channel estimation and the influence of noise and interference, it is still impossible to completely eliminate the influence of the modulo operation, so the signal will be Transmission causes performance loss. Summary of the invention

A precoding method, system and device are provided in an embodiment of the present invention. It is possible to minimize the adverse effects of power limiting operations on signal transmission while limiting power.

The embodiment of the invention provides a precoding method, including:

Performing precoding pre-processing on the transmitted signal, the pre-processing processing increasing the power of the signal to be transmitted;

Selecting a power limiting algorithm according to a selection rule;

Performing a power limiting operation on the pre-processed signal according to the selected power limiting algorithm; generating a pre-coded signal according to the signal after the power limiting operation.

The embodiment of the invention further provides a precoding method, including:

Receiving modulo information sent by the transmitter;

And determining, according to the modulo information, whether the transmitter performs a modulo operation on the pre-coded pre-processed signal, and if the determination is YES, performing a modulo recovery operation on the received signal.

An embodiment of the present invention further provides a transmitter, including:

a precoding pre-processing module, configured to perform precoding pre-processing on the signal to be transmitted, where the pre-processing increases the power of the signal to be transmitted;

a power limiting algorithm selecting module, configured to select a power limiting algorithm according to a selection rule; and a power limiting module, configured to perform a power limiting operation on the pre-processed signal according to the selected power limiting algorithm;

a pre-coded signal generating module for generating a pre-coded signal according to a signal after the power limitation operation Signal.

The embodiment of the invention further provides a receiver, including:

a modulo information receiving module, configured to receive modulo information sent by the transmitter;

a modulo judging module, configured to determine, according to the modulo information, whether the transmitter performs a modulo operation on the pre-coded pre-processed signal;

The modulo recovery module is configured to perform a modulo recovery operation on the received signal when the judgment result of the modulo judgment module is YES.

An embodiment of the present invention further provides a precoding system, including a transmitter and a receiver, where the transmitter includes:

The pre-coded signal generating module is configured to generate a pre-coded signal according to the signal after the power limitation operation.

The embodiments of the present invention have the following beneficial effects: By adaptively selecting different power limiting algorithms in different situations, not only the transmission power is controlled to meet the limitation of hardware conditions, but also the pair caused by the power limiting operation is reduced as much as possible. The adverse effects of the transmitted signal. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description Only some embodiments of the present invention, for those of ordinary skill in the art, do not pay Other drawings can also be obtained from these drawings on the premise of creative labor.

1 is a schematic diagram of a conventional transmitter side precoding method;

2 is a schematic diagram of a conventional receiver side precoding method;

3 is a flow chart of a first embodiment of a precoding method on the transmitter side provided by the present invention; FIG. 4 is a flow chart of a second embodiment of a precoding method on the transmitter side provided by the present invention; A flowchart of a first embodiment of a precoding method on the receiver side; FIG. 6 is a schematic structural diagram of a first embodiment of a transmitter provided by the present invention;

7 is a schematic structural view of a second embodiment of a transmitter provided by the present invention;

FIG. 8 is a schematic structural diagram of a second embodiment of a receiver provided by the present invention. detailed description

BRIEF DESCRIPTION OF THE DRAWINGS The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of the present invention.

Referring to FIG. 3, it is a flowchart of a first embodiment of a precoding method on a transmitter side provided by the present invention, including:

In step S300, pre-coding pre-processing is performed on the signal to be transmitted, and the pre-processing increases the power of the signal to be transmitted. For example, the pre-processing may include all processing steps in the pre-coding algorithm that may cause an increase in signal power, such as processing for serially eliminating inter-signal interference.

In step S301, a power limiting algorithm is selected according to the selection rule. For example, the selection rules include: selecting a power limiting algorithm with minimal performance loss, where the performance loss is the difference between the quality of communication after performing the power limiting operation and the quality of communication when the power limiting operation is not performed. The selection rules may also include: selecting a power limiting algorithm that may produce the least noise. A plurality of power limiting algorithms can be pre-stored and then the most appropriate one can be selected in a particular situation according to the selection rules. In step S302, a power limiting operation is performed on the pre-processed signal according to the selected power limiting algorithm.

In step S303, a precoded signal is generated based on the signal after the power limitation operation. Specifically, some precoding subsequent processing may be performed on the signal after the power limiting operation, and the subsequent processing may include remaining processing steps after performing preamble processing and power limiting processing in the precoding algorithm, for example, mapping the signal stream to the antenna. Processing.

The precoding method provided by the embodiment of the present invention not only controls the transmission power to meet the limitation of the hardware condition but also reduces the transmission caused by the power limitation operation by adaptively selecting different power limitation algorithms in different situations. The adverse effects of the signal.

Referring to FIG. 4, it is a flow chart of a second embodiment of a precoding method on the transmitter side provided by the present invention, including:

In step S400, pre-coding pre-processing is performed on the signal to be transmitted, and the pre-processing increases the power of the signal to be transmitted. Taking ZF-THP as an example, it is assumed that the number of antennas at both ends of the transceiver is symmetric, both are K, and the signal to be transmitted is a ₂ , a _K . The precoding pre-processing includes: obtaining the channel matrix H according to the feedback of the receiver or according to the uplink The frequency channel estimation obtains an approximate downlink channel matrix H, and H is decomposed to obtain H=LQ ^H , where L is a lower triangular matrix with a dimension of K x K, and Q is a unitary matrix of dimension K x K, and the decomposition can be This is achieved by QR decomposition of H ^H , where H ^H represents the conjugate transpose of H; then, matrix B is obtained from B = GL, where G is the diagonal matrix of the inverse of the diagonal elements of L, so B is A lower triangular matrix with a diagonal element of 1; the pre-processed signal is calculated according to _3⁄4 = a _k -| k = l,2,.-, K, where u _k represents the pre-processed

1=1

The signal, a _k represents the signal to be transmitted, represents the element of the kth row and the first column of B, and represents the signal after the power limiting operation. As can be seen from the above process, due to the influence of the ^b _MVl on the right side of the formula,

1=1

The power of u _k will be greater than the power of a _k , so it is necessary to power limit the pre-coded pre-processed signal. Operation to limit the transmit power.

In step S401, it is determined according to the selection rule whether the modulo algorithm is selected in the modulo algorithm and the non-modulo power limiting algorithm. The modulo algorithm includes: determining a modulo offset, using the sum of the modulo offset and the pre-processed signal as a signal after the modulo operation, and the amplitude of the signal after the modulo operation does not exceed Set the amplitude threshold. The non-modulo power limiting algorithm may include a linear power limiting algorithm or other nonlinear power limiting algorithm other than the modulo algorithm. Taking a linear power limiting algorithm as an example, the algorithm includes: determining a power limiting factor, multiplying the power limiting factor The previously processed signal, or multiplying the power limiting factor by the signal to be transmitted included in the previously processed signal, and using the multiplied signal as a linear power limiting operation signal, and after the linear power limiting operation The power of the signal does not exceed the preset power threshold. Although both modulo operation and linear power limiting operation can better limit power, and there is a certain performance loss compared to not performing power limiting operation, their performance loss is different under different conditions. For example, when the channel state and/or channel quality is poor, the performance loss caused by the linear power limiting operation is extremely large, and when the channel state and/or channel quality is relatively good, the performance loss of the linear power limiting operation may be less than The modulo operation, so the selection rule may include: selecting one of a modulo algorithm and a linear power limiting algorithm according to the current channel state and/or channel quality. For example, when the measured value of one or more indicators of the current channel state and/or channel quality is greater than a preset threshold, the performance loss of the modulo operation is considered to be less than the performance loss of the linear power limiting operation, so the modulo algorithm is selected; When the measured value of one or more indicators of channel state and/or channel quality is less than a predetermined threshold, the performance loss of the modulo operation is considered to be greater than the performance loss of the linear power limiting operation, and thus the linear power limiting algorithm is selected. The indicators of channel state and/or channel quality include signal to noise ratio, inter-antenna correlation, channel correlation between users, and the like. In order to better ensure the communication quality, a more comprehensive factor may be selected when selecting the power limiting algorithm. For example, step S401 may include: determining whether to select a modulo algorithm according to performance loss of the modulo algorithm and performance loss of the linear power limiting algorithm, below Taking the modulo algorithm and the linear power limit algorithm as an example, how to estimate the performance loss Lost details.

Preferably, in step S401, the performance loss of the modulo algorithm is estimated based on the current channel state, channel quality, and/or current modulation coding mode. Specifically, the performance loss caused by the modulo operation at this time may be estimated according to the current channel state and/or channel quality and pre-stored modulo operation performance loss under different channel states and/or channel qualities, and/or The performance loss caused by the modulo operation at this time can be estimated according to the current modulation coding mode and the modulo operation performance loss under different modulation coding modes stored in advance. The performance loss of the modulo algorithm under different channel states and/or channel qualities or in different modulation coding modes can be determined by pre-calculation, simulation or measurement.

Preferably, in step S401, the performance loss of the linear power limiting algorithm is estimated based on the power loss of the useful signal power after the linear power limiting operation relative to the useful signal power before the linear power limiting operation. For example, assuming that the power limit factor calculated according to the above method is ^T k , the loss of useful signal power (in dB) after power limiting operation is -ιοι, compared to the power of the useful signal before normalization. . . Specifically, the performance loss of the linear power limiting operation may be estimated according to the power loss of the useful signal power after the linear power limiting operation relative to the power loss of the useful signal power before the linear power limiting operation and the pre-stored power loss versus performance loss, The correspondence between power loss and performance loss can be obtained by pre-simulation, calculation or measurement. In addition to this, the power loss of the useful signal power after the linear power limiting operation with respect to the useful signal power before the linear power limiting operation can be directly used as the performance loss of the linear power limiting operation.

If the result of the determination in step S401 is YES, step S402 is performed. In step S402, a modulo operation is performed on the pre-coded pre-processed signal, and the modulo operation includes adding a pre-coded pre-processed signal to a modulo offset. The ZF-THP is also taken as an example. The signal after the modulo operation is v _k = a _k + p _k — |^ _νι , k = l, 2, - - -, K , where p _k is the modulo offset Through the modulo operation, v _k Both the real and imaginary parts are limited to a certain extent, so their power will also be limited to the target range.

If the result of the determination in step S401 is NO, step S403 is performed. In step S403, a non-modulo power limiting operation, such as a linear power limiting operation, is performed on the precoded preprocessed signal. Taking the linear power limiting operation in the ZF-THP algorithm as an example, step S403 specifically includes: determining a power limiting factor _Tk such that the power of the signal after the linear power limiting operation _Vk = _TA - £b _uVl does not exceed a preset power threshold. .

In step S404, the signal after the power limiting operation is subjected to precoding subsequent processing to generate a precoded signal. The pre-coding subsequent processing is also described by taking ZF-THP as an example. Subsequent processing includes: multiplying the signal v _k ( k=l, 2, ...K ) after the modulo operation or the linear power limiting operation with the matrix Q obtained in the pre-processing to obtain the pre-coded signal x _k ( k = l, 2, ... K ), ie x = Qv, where

In step S405, modulo information for indicating whether the transmitter has performed a modulo operation on the precoded preprocessed signal is transmitted to the receiver. The modulo information can be used by the receiver to determine whether to perform a modulo recovery operation on the received signal based on the modulo information. The modulo recovery operation performed by the receiver is the same as the modulo operation performed by the transmitter. Since the modulo operation interferes with the wanted signal, in order to alleviate the performance loss of the modulo operation, it is necessary to perform the same modulo recovery operation on the receiver side as the transmitter side on the receiver side; however, if the transmitter side The power limiting algorithm is a linear power limitation that eliminates the need to perform a modulo recovery operation on the received signal at the receiver side. Therefore, by transmitting to the receiver whether or not the modulo information for performing the modulo operation on the pre-coded pre-processed signal, the performance loss of the transmitted signal can be better reduced, and the unnecessary modulo recovery operation band can be prevented from being performed on the receiver side. The loss has improved the quality of communication.

Although the present embodiment is described by taking ZF-THP as an example, the present invention is not limited to the ZF-THP precoding algorithm, but can be applied to any precoding algorithm that may cause performance loss to the transmitted signal. E.g, In another nonlinear precoding algorithm MMSE-THP (Minimum Mean Square Error Tomlinson-Harashima precoding), the pre-processing includes: through the matrix H ^H + The QR decomposition of O^ yields the matrix Q and the matrix Β, where ξ4 is the noise power of the receiver, which is the power of the signal V after the power limiting operation; represents the pseudo-inverse of the matrix ,, if the number of rows of Η is greater than or equal to the number of columns , then H ^† = (H ^H H)—if the number of columns in Η is greater than the number of rows, then

) — ¹ » The other steps of the algorithm are similar to ZF-THP, with

Compared to ZF-THP, the algorithm considers noise and interference on the receiver side. For the modulo information, it can be used to transmit the channel alone or in combination with other communication necessary signals. Transmitting the modulo information with other necessary communication signals eliminates the need for additional channel resources. In the following, the LTE communication system will be taken as an example to describe the method of transmitting modulo information.

Preferably, in step S405, the modulo information is included in the downlink control signal control channel for indicating the downlink scheduling, and the modulo information is sent together with the scheduling information used to indicate the downlink scheduling, to indicate that the scheduling information is indicated. Whether the PDSCH (Physical Downlink Shared Channel) codeword is subjected to modulo operation. The PDSCH is used to carry data from the DSCH (Downlink Shared Channel), which is the carrier of the DSCH, and the PDSCH codeword is the signal sent by the transmitter.

Preferably, in step S405, the modulo information may also be implicit in a UE (User Equipment) dedicated reference signal. Specifically, it is assumed that the UE-specific reference signal on the antenna port p is ^a(P ). If the data transmitted by the antenna port is modulo, the ^{a = a} , if the transmitter side does not have the antenna port The transmitted data is modulo, so let ^{a =} - ^a . The opposite process can also be used, that is, when the modulus is not found ^) : -^), the modulus is ordered ^^ ^). Load in this way Modulo operation information, as a new UE-specific reference signal with ^a pre-encoded and transmitted instead of ^a. The rationality of the method is still explained below by taking ZF-THP as an example. Ideally, after the UE-specific reference signal arrives at the receiver, its equivalent channel is the diagonal element of L, and the characteristics of the matrix QR decomposition show that the diagonal element of L can always be a positive real number (or a negative real number). ). Therefore, when performing channel estimation, the transmitter side UE can always assume that the equivalent channel (or the diagonal element of L) is a positive real number (or a negative real number) and multiply the data symbol of the UE-specific reference signal by 1 ( -1) and -1 (1) represent the two cases of modulo and non-modulo, respectively. In this way, by detecting the symbol of the UE reference signal, the receiver-side UE can determine whether the data on the antenna port corresponding to the UE reference signal is subjected to a modulo operation. For example, when the pilot symbol of the UE-specific reference signal is positive, the modulo information indicates that the receiver needs to perform a modulo operation on the received signal; when the pilot symbol of the UE-specific reference signal is negative, the modulo information indicates reception. The machine does not need to perform a modulo operation on the received signal; wherein, the equivalent channel of the UE-specific reference signal defaults to a positive real number.

Referring to FIG. 5, it is a flowchart of a first embodiment of a receiver-side precoding method provided by the present invention, including:

At step S500, modulo information transmitted by the transmitter is received.

Preferably, in step S500, the modulo information is included in a downlink control signal for indicating downlink scheduling.

Preferably, in step S500, the modulo information is implicit in the UE-specific reference signal.

In step S501, it is determined according to the modulo information whether the transmitter performs a modulo operation on the pre-coded pre-processed signal. For example, if the modulo information is implicit in the UE-specific reference signal, channel estimation may be performed on the equivalent channel of the user equipment-specific reference signal, and judged according to the real symbol of the equivalent channel of the default user equipment-specific reference signal. The factor multiplied by the user equipment-specific reference signal is 1 or -1 to judge the meaning of the modulo information. For example, when the pilot symbol of the UE-specific reference signal is positive, the modulo information indicates that the receiver needs to perform a modulo operation on the received signal; When the pilot symbol of the dedicated reference signal is negative, the modulo information indicates that the receiver does not need to perform a modulo operation on the received signal; wherein the equivalent channel of the UE-specific reference signal defaults to a positive real number.

If the decision result in the step S501 is YES, the step S502 is executed. In step S502, a modulo recovery operation is performed on the received signal. Preferably, the process of the modulo recovery operation is the same as the modulo operation.

If the decision result in the step S501 is NO, the flow of the method ends.

The precoding method provided by the embodiment of the present invention determines whether the modulo recovery operation is performed on the received signal by using the modulo information, which not only reduces the adverse effect on the transmission signal caused by the power limiting operation, but also avoids unnecessary execution. Seek mode recovery operation.

Referring to FIG. 6, FIG. 6 is a schematic structural diagram of a first embodiment of a transmitter provided by the present invention. The transmitter 60 includes:

The precoding preprocessing module 610 is configured to perform precoding preprocessing on the signal to be transmitted, where the preamble processing increases the power of the signal to be transmitted. For example, the pre-processing may include all processing steps in the pre-coding algorithm that may cause an increase in signal power, such as processing to eliminate serial interference between signal streams.

The power limiting algorithm selection module 620 is configured to select a power limiting algorithm according to a selection rule. For example, the selection rules include: selecting a power limiting algorithm with minimal performance loss, where the performance loss is the difference between the quality of the communication after performing the power limiting operation and the quality of the communication when the power limiting operation is not performed. The selection rules may also include: selecting a power limiting algorithm that may produce the least noise. The power limiting algorithm selection module 620 can select the most appropriate one of the pre-stored power limiting algorithms in a particular situation based on the selection rules.

The power limiting module 630 is configured to perform a power limiting operation on the pre-processed signal according to the selected power limiting algorithm.

The pre-coded signal generating module 640 is configured to generate a pre-coded signal according to the signal after the power limitation operation. Specifically, the pre-coded signal generating module 640 can perform a signal after the power limiting operation Some precoding subsequent processing is performed, which may include the remaining processing steps after the preamble processing and the power limiting processing are completed in the precoding algorithm, such as processing for mapping the signal stream to the antenna.

The transmitter provided by the embodiment of the present invention not only controls the transmission power to meet the limitation of the hardware condition, but also reduces the transmission signal caused by the power limitation operation by adaptively selecting different power limitation algorithms in different situations. The adverse effects.

Referring to FIG. 7, which is a schematic structural diagram of a second embodiment of a transmitter provided by the present invention, the transmitter 70 includes:

The precoding pre-processing module 710 is configured to perform precoding pre-processing on the signal to be transmitted, where the pre-processing increases the power of the signal to be transmitted. Taking ZF-THP as an example, it is assumed that the number of antennas at both ends of the transceiver is symmetric, both are K, and the signal to be transmitted is a ₂ , a _K . The precoding pre-processing includes: obtaining the channel matrix H according to the feedback of the receiver or according to the uplink The channel estimation of the pilot obtains an approximate downlink channel matrix H, and H is decomposed to obtain H = LQ ^H , where L is a lower triangular matrix of dimension KXK, and Q is a unitary matrix of dimension K x K, and the decomposition can be QR decomposition of ^Η Η implemented, where [eta] represents ^Η Η conjugate transpose; then, according to B = GL obtained matrix B, wherein G is a diagonal matrix of the inverse of the diagonal elements of the composition L, and thus a B The lower triangular matrix with a diagonal element of 1; the pre-processed signal is calculated according to u _k = a _k - |^b _MVl , k = l,2,. -, K, where u _k represents the former

1=1

The processed signal, a _k represents the signal to be transmitted, and bid represents the element of the kth row and the first column of B, indicating the signal after the power limiting operation. As can be seen from the above process, due to the right side of the formula |3⁄4b _MVl

1=1 The influence of this item, u _k power is greater than the power of 3⁄4, so it is necessary to perform power limiting operation on the pre-coded pre-processed signal to limit the transmit power.

The power limiting algorithm selecting module 720 is configured to determine, according to the selection rule, whether to select a modulo algorithm in the modulo algorithm and the non-modulo power limiting algorithm. The modulo algorithm includes: determining a modulo offset, using the sum of the modulo offset and the pre-processed signal as a signal after the modulo operation, and performing a modulo operation The amplitude of the subsequent signal does not exceed the preset amplitude threshold. The non-modulo power limiting algorithm may include a linear power limiting algorithm or other nonlinear power limiting algorithm other than the modulo algorithm. Taking a linear power limiting algorithm as an example, the algorithm includes: determining a power limiting factor, multiplying the power limiting factor The previously processed signal, or multiplying the power limiting factor by the signal to be transmitted included in the previously processed signal, and using the multiplied signal as a linear power limiting operation signal, and after the linear power limiting operation The power of the signal does not exceed the preset power threshold. Although both modulo operation and linear power limiting operation can better limit power, and there is a certain performance loss compared to not performing power limiting operation, the performance loss caused by them in different situations is different. For example, when the channel state and/or channel quality is poor, the performance loss caused by the linear power limiting operation is extremely large, and when the channel state and/or channel quality is relatively good, the performance loss of the linear power limiting operation may be less than The modulo operation, so the selection rule may include: selecting one of a modulo algorithm and a linear power limiting algorithm according to the current channel state and/or channel quality. For example, when the measured value of one or more indicators of the current channel state and/or channel quality is greater than a preset threshold, the performance loss of the modulo operation is considered to be less than the performance loss of the linear power limiting operation, so the power limiting algorithm selection module 720 selects A modulo algorithm; when the measured value of one or more indicators of the current channel state and/or channel quality is less than a preset threshold, the performance loss of the modulo operation is considered to be greater than the performance loss of the linear power limiting operation, and thus the power limiting algorithm selection module 720 selects a linear power limiting algorithm. The indicators of channel state and/or channel quality include signal to noise ratio, inter-antenna correlation, channel correlation between users, and the like. In order to better ensure communication quality, the power limiting algorithm selection module 720 can be based on more comprehensive factors when selecting the power limiting algorithm. For example, the limiting algorithm selection module 720 can judge the performance loss of the modulo algorithm and the performance loss of the linear power limiting algorithm. Whether the modulo algorithm is selected, the modulo algorithm and the linear power limiting algorithm will be taken as an example to describe how the power limiting algorithm selection module 720 estimates the performance loss.

Preferably, the power limiting algorithm selection module 720 can estimate the performance loss of the modulo algorithm based on the current channel state, channel quality, and/or current modulation coding scheme. Specifically, the power limit is calculated The method selection module 720 can estimate the performance loss that may be caused by the modulo operation at this time according to the current channel state and/or channel quality and pre-stored modulo operation performance loss under different channel states and/or channel qualities, and/or Alternatively, the performance loss caused by the modulo operation at this time may be estimated according to the current modulation coding mode and the modulo operation performance loss under different modulation coding modes stored in advance. The performance loss of the modulo algorithm under different channel states and/or channel qualities or in different modulation and coding modes can be determined by pre-calculation, simulation or measurement.

Preferably, the power limiting algorithm selection module 720 can estimate the performance loss of the linear power limiting algorithm based on the power loss of the useful signal power after the linear power limiting operation relative to the useful signal power before the linear power limiting operation. For example, assuming that the power limit factor calculated according to the above method is, the loss of useful signal power (in the form of _d B ) after the power limiting operation is -ιοι as compared with the power of the useful signal before normalization. . Specifically, the power limiting algorithm selection module 720 can estimate the linear power according to the power loss of the useful signal power after the linear power limiting operation relative to the power loss of the useful signal power before the linear power limiting operation and the pre-stored power loss and performance loss. Limiting the performance loss of operation, the correspondence between power loss and performance loss can be obtained by pre-simulation, calculation or measurement. In addition, the power limiting algorithm selection module 720 can directly use the power loss of the useful signal power after the linear power limiting operation relative to the useful signal power before the linear power limiting operation as the performance loss of the linear power limiting operation.

The modulo module 730 is configured to: when the determination result of the power limiting algorithm selection module 720 is YES, perform a modulo operation on the pre-coded pre-processed signal, and the modulo operation includes adding a pre-coded pre-processed signal to the modulo operation. The modulo offset. Similarly, ZF-THP is taken as an example. The signal after the modulo operation is v _k = a _k + _Pk — |^ _{13⁄4 νι} , k = l, 2, - - - , K , where p _k is the modulo offset Through the modulo operation, v _k

1=1

Both the real and imaginary parts are limited to a certain extent, so their power will also be limited to the target range. The non-modulo power limiting module 740 is configured to determine the result of the power limiting algorithm selection module 720 In the case of no, the pre-coded pre-processed signal is subjected to a non-modulo power limiting operation, such as a linear power limiting operation. Taking ZF-THP as an example, the linear power limiting operation includes: determining a power limiting factor T _K such that the power of the signal v _K = T _A - |^b _MV1 after the linear power limiting operation does not exceed a preset power threshold.

1=1

The pre-coded signal generating module 740 is configured to perform pre-coding subsequent processing on the signal after the modulo operation or the linear power limiting operation to generate a pre-coded signal. The pre-coding subsequent processing is also described by taking ZF-THP as an example. Subsequent processing includes: multiplying the signal v _k ( k=l, 2, ...K ) after the modulo operation or the linear power limiting operation with the matrix Q obtained in the pre-processing to obtain the pre-coded signal x _k ( k = l, 2, ~ K ), ie x = Qv, where XXV ' XK) ¹¹ , _V = ( _VI , V ₂ , _VK ) ^H . The modulo information sending module 760 is configured to send, to the receiver, modulo information for indicating whether the transmitter has performed a modulo operation on the pre-coded pre-processed signal, so that the receiver determines, according to the modulo information Whether to perform a modulo recovery operation on the received signal. The modulo recovery operation performed by the receiver is the same as the modulo operation performed by the transmitter. Since the modulo operation interferes with the wanted signal, in order to alleviate the performance loss of the modulo operation, it is necessary to perform the same modulo recovery operation on the receiver side as the transmitter side on the receiver side; however, if the transmitter side The power limiting algorithm is a linear power limitation that eliminates the need to perform a modulo recovery operation on the received signal at the receiver side. Therefore, by transmitting to the receiver whether or not the modulo information for performing the modulo operation on the pre-coded pre-processed signal, the performance loss of the transmitted signal can be better reduced, and the unnecessary modulo recovery operation band can be prevented from being performed on the receiver side. The loss has improved the quality of communication.

Although the present embodiment is described by taking ZF-THP as an example, the present invention is not limited to the ZF-THP precoding algorithm, but can be applied to any precoding algorithm that may cause performance loss to the transmitted signal. For example, in another nonlinear precoding algorithm MMSE-THP (Minimum Mean Square Error Tomlinson-Harashima precoding), the pre-processing includes: QR decomposition of ^H + O^ yields matrix Q and matrix Β, where ξ = 4, is the noise power of the receiver, is the power of the signal V after the power limit operation; represents the pseudo inverse of the matrix ,, if the number of rows of Η is greater than or equal to the number of columns, then H ^† = (H ^H H)— If the number of columns in Η is greater than the number of rows, then

) — ¹ » The other steps of the algorithm are similar to ZF-THP, with

Compared to ZF-THP, the algorithm considers noise and interference on the receiver side. For the modulo information, it can be used to transmit the channel alone or in combination with other communication necessary signals. Transmitting the modulo information with other necessary communication signals eliminates the need for additional channel resources. The method of transmitting the modulo information to the modulo information transmitting module 760 will be described below by taking the LTE communication system as an example.

Preferably, the modulo information transmitting module 760 can transmit the modulo information in the downlink control signaling for indicating the downlink scheduling. Specifically, the modulo information sending module 760 may send the modulo information together with the scheduling information used to indicate the downlink scheduling in the PDCCH (Physical Downlink Control Channel) to indicate the indication indicated by the scheduling information. Whether the PDSCH (Physical Downlink Shared Channel) codeword is subjected to modulo operation. The PDSCH is used to carry data from the DSCH (Downlink Shared Channel), which is the carrier of the DSCH, and the PDSCH codeword is the signal sent by the transmitter.

Preferably, the modulo information sending module 760 can implicitly modulate the modulo information in a UE (User Equipment) dedicated reference signal for transmission. Specifically, it is assumed that the UE-specific reference signal on the antenna port p is ^a(P) , if the transmitter side transmits the data transmitted by the antenna port.

-(p) (p)

Modulo, then let ^{a = a} , if the transmitter side does not model the data transmitted by the antenna port, then ^) = - a( ^p ). The opposite process can also be used, that is, when the modulus is not found ^) = - ^a(P ), the modulus is ^a ~ ^{(P) = a(P} ). After the modulo information is loaded in this manner, ^{δ(Ρ) is used} instead of ^a(P) as a new UE-specific reference signal for precoding and transmission. The rationality of the method is still explained below by taking ZF-THP as an example. Rational If the UE-specific reference signal arrives at the receiver, the equivalent channel is the diagonal element of L, and the characteristics of the matrix QR decomposition show that the diagonal element of L can always be a positive real number (or a negative real number). ). Therefore, when performing channel estimation, the transmitter side UE can always assume that the equivalent channel (or the diagonal element of L) is a positive real number (or a negative real number) and multiply the data symbol of the UE-specific reference signal by 1 ( -1) and -1 (1) represent the case of modulo and not modulo, respectively. In this way, by detecting the symbol of the UE reference signal, the receiver-side UE can determine whether the data on the antenna port corresponding to the UE reference signal is subjected to a modulo operation. For example, when the pilot symbol of the UE-specific reference signal is positive, the modulo information indicates that the receiver needs to perform a modulo operation on the received signal; when the pilot symbol of the UE-specific reference signal is negative, the modulo information indicates reception. The machine does not need to perform a modulo operation on the received signal; wherein, the equivalent channel of the UE-specific reference signal defaults to a positive real number.

Referring to FIG. 8, FIG. 8 is a schematic structural diagram of a first embodiment of a receiver provided by the present invention, where the receiver 80 includes:

The modulo information receiving module 810 is configured to receive modulo information sent by the transmitter.

Preferably, the modulo information is included in downlink control signaling for indicating downlink scheduling.

Preferably, the modulo information is implicit in the UE-specific reference signal.

The modulo judging module 820 is configured to determine, according to the modulo information, whether the transmitter performs a modulo operation on the pre-coded pre-processed signal.

Preferably, the modulo determination module 820 can perform channel estimation on the equivalent channel of the user equipment-specific reference signal, and determine the user equipment-specific reference signal according to the symbol of the real part of the equivalent channel of the default user equipment-specific reference signal. The multiplication factor is 1 or -1 to judge the meaning of the modulo information. For example, when the pilot symbol of the UE-specific reference signal is positive, the modulo information indicates that the receiver needs to perform a modulo operation on the received signal; when the pilot symbol of the UE-specific reference signal is negative, the modulo information indicates reception. The machine does not need to perform a modulo operation on the received signal; wherein, the equivalent channel of the UE-specific reference signal defaults to a positive real number. . The modulo recovery module 830 is configured to perform a modulo recovery operation on the received signal when the modulo determination mode is YES. Preferably, the modulo recovery operation performed by the modulo recovery module 830 is the same as the modulo operation performed by the modulo module.

The receiver provided by the embodiment of the present invention determines whether the modulo recovery operation is performed on the received signal according to the modulo information, which not only reduces the adverse effect on the transmission signal caused by the power limiting operation, but also avoids unnecessary execution. Seek mode recovery operation.

The present invention also provides a precoding system and a precoding method performed by the precoding system, the precoding system comprising the transmitter and receiver described in any of the above embodiments.

A person skilled in the art can understand that all or part of the process of implementing the above embodiment method can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium, the program When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The above is only a preferred embodiment of the present invention, and of course, the scope of the present invention is not limited thereto, and those skilled in the art can understand all or part of the process of implementing the above embodiments, and according to the present invention. The equivalent changes required are still within the scope of the invention.

Claims

Rights request

A precoding method, comprising:

Selecting a power limiting algorithm according to a selection rule;

2. The precoding method according to claim 1, wherein the selecting rule comprises: selecting a power limiting algorithm with a minimum performance loss, the performance loss being a communication quality after power limiting operation and no power limitation The difference between the quality of communication during operation.

The precoding method according to claim 1 or 2, wherein the power limiting algorithm comprises a modulo algorithm and a non-modulo power limiting algorithm;

The step of selecting a power limiting algorithm according to the selection rule comprises: selecting one of a modulo algorithm and a non-modulo power limiting algorithm according to a selection rule.

4. The precoding method according to claim 3, wherein the method further comprises: transmitting, to the receiver, a modulo indicating whether the transmitter has performed a modulo operation on the precoded preprocessed signal. information.

The precoding method according to claim 1, wherein the step of generating a precoded signal according to the signal after the power limiting operation comprises: performing precoding subsequent processing on the signal after the power limiting operation, Generate a precoded signal.

6. The method according to claim 3, wherein the non-modulo power limiting algorithm comprises a linear power limiting algorithm, the linear power limiting algorithm comprising: determining a power limiting factor, multiplying the power limiting factor by a previous The processed signal, or multiplying the power limiting factor by the signal to be transmitted included in the previously processed signal, and using the multiplied signal as a signal after the non-modulo power limiting operation, and the non-seeking The power of the signal after the mode power limiting operation does not exceed the preset power threshold.

The precoding method according to claim 2, wherein the performance loss of the power limiting algorithm is useful according to a power limiting operation corresponding to the power limiting algorithm after the operation of the useful signal power relative to the power limiting operation The power loss of the signal power is estimated.

8. The precoding method according to claim 3, wherein the performance loss of the modulo algorithm is estimated according to a current channel state, a channel quality, or a current modulation coding mode.

The precoding method according to claim 4, wherein the modulo information is included in downlink control signaling for indicating downlink scheduling.

10. The precoding method according to claim 4, wherein the modulo information is implicit in a user equipment specific reference signal.

The precoding method according to claim 10, wherein the modulo information is represented by multiplying a symbol of the user equipment-specific reference signal by 1 or -1, wherein the user equipment-specific reference signal The sign of the real part of the equivalent channel defaults to positive or negative.

12. A precoding method, comprising:

Receiving modulo information sent by the transmitter;

The precoding method according to claim 12, wherein the modulo information is implicit in a user equipment specific reference signal;

The step of determining, according to the modulo information, whether the transmitter performs a modulo operation on the pre-coded pre-processed signal specifically includes:

Channel estimation is performed on the equivalent channel of the user equipment-specific reference signal, and the factor multiplied by the user equipment-specific reference signal is judged to be 1 or -1 according to the real part of the equivalent channel of the default user equipment-specific reference signal.

14. A transmitter, comprising:

The transmitter according to claim 14, wherein the power limiting algorithm package The modulo algorithm and the non-modulo power limiting algorithm are used, and the power limiting algorithm selecting module is configured to select one of a modulo algorithm and a non-modulo power limiting algorithm according to a selection rule.

The transmitter according to claim 14, wherein the transmitter further comprises: a modulo information sending module, configured to send, to the receiver, a signal indicating whether the transmitter has processed the precoding preamble The modulo information of the signal for the modulo operation.

17. A receiver, comprising:

18. A precoding system comprising a transmitter and a receiver, wherein the transmitter comprises:

19. The precoding system of claim 18, wherein:

The transmitter further includes:

a modulo information sending module, configured to send, to the receiver, modulo information for indicating whether the transmitter has performed a modulo operation on the pre-coded pre-processed signal;

The receiver includes: