CN102957502B - For the method and apparatus of the linear predictive coding of communication system - Google Patents

Abstract

The invention discloses a kind of method and apparatus of the linear predictive coding for communication system.The method comprises: according to the characteristic of channel of the subcarrier relevant to the current sub-carrier of i-th subscriber equipment, arranges the initial value of the received beam forming matrix RBFM of this current sub-carrier according to the RBFM of this i-th subscriber equipment in the p-1 time iteration determine that in the p time iteration, the equivalent combined channel of this i-th subscriber equipment mends matrix wherein p is natural number; Obtain and form this equivalent combined channel benefit matrix a left side zero fall into the right singular vector set in space and by this right singular vector set be set to the transmit beam-forming matrix T BFM of this i-th subscriber equipment in the p time iteration according to the TBFM of convergence rule by this i-th subscriber equipment be set to the pre-coding matrix F of this i-th subscriber equipment _i.The method and apparatus of the embodiment of the present invention fast and obtain pre-coding matrix simply, and can increase the throughput of system, elevator system performance.

Description

Method and apparatus for linear precoding for communication systems

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for linear precoding for a communication system in the field of communications.

Background

multi-User (MU) MIMO has become a focus of recent research because of the large potential of system gain due to Space Division Multiple Access (SDMA) in a Multiple-Input Multiple-Output (MIMO) system.

MIMO technology was first applied in single-user systems, with joint processing on all transmit and receive antennas resulting in MIMO gain. However, when the MIMO technology is applied to MU scenarios, the inability to coordinate between users is a key issue. For uplink and downlink communication in a cellular network, in the uplink communication, Multiple users transmit information to a base station at the same time and at the same frequency, and the base station may adopt a technology similar to multi-User Detection (hereinafter, referred to as "MUD") to separate signals of different users; in downlink transmission, the base station simultaneously sends signals to the users. Therefore, in the received signal of each user, there is a part of the interference between users caused by other user signals. Although in theory a User may employ a Multi-User Interference (MUI) cancellation technique that employs Multi-User detection MUD, it is generally desirable to cancel MUI at the base station side in view of the requirements of low power consumption, low complexity, and low cost of the User.

The interference between users can be eliminated by linear and nonlinear precoding techniques at the base station side. The linear precoding technology has the characteristic of low computational complexity, and has good robustness under the condition that Channel state information (CSI for short) is incomplete; compared with the linear precoding technology, the nonlinear precoding technology has higher computational complexity and is sensitive to the accuracy of the CSI. However, the linear precoding method in the prior art is generally complicated and requires the number of transmit antennas to be greater than the number of receive antennas.

In the current research, a wireless communication system is proposed, which does not limit the number of receiving antennas of an Access Point (AP) and an end user. In this patent, in order to break the limitation that the number of transmit antennas must be greater than the number of Receive antennas, an AP generates a Receive Coefficient Matrix (also referred to as a Receive Beamforming Matrix (RBFM) for short) using a training sequence transmitted by an end user, and multiplies the channel Matrix to form an equivalent transmit Coefficient Matrix when the number of Receive antennas does not exceed the number of transmit antennas. The method can be used for eliminating the interference among multiple users. Therefore, the transmission coefficient matrix a can be calculated. And then, in the equivalent single-user transmission after the multi-user interference is eliminated, adopting an MIMO transmission strategy to obtain receiving coefficient matrixes V and U. On the user side, the data recovery can be performed by knowing the reception coefficient matrices V and U. Before sending data, however, the transmitting end must send the receiving coefficient matrix to the receiving end user. Therefore, although the method can break the limitation of the number of antennas, the method is complex, has high system overhead, and easily causes waste of communication time and frequency resources.

Therefore, there is a need for a simple and fast linear precoding method, and the linear precoding method has no limitation on the number of antennas at the transmitting end and the receiving end.

Disclosure of Invention

The embodiment of the invention provides a linear precoding method and device for a communication system, which can quickly and simply acquire a precoding matrix and have no limit on the number of antennas at a transmitting end and a receiving end.

In one aspect, embodiments of the present invention provide a method for communicationMethod for linear precoding in a communication system comprising a plurality of antennas with M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiBeing a natural number, the method comprises: setting an initial value of a receive beamforming matrix RBFM of a current subcarrier of the ith UE according to channel characteristics of the subcarrier related to the current subcarrierAccording to the RBFM of the ith user equipment in the p-1 iterationDetermining an equivalent joint channel complementary matrix of the ith user equipment in the p iterationWherein p is a natural number; by complementing the equivalent joint channel of the ith user equipment with a matrixSingular value decomposition is carried out to obtain and form the equivalent joint channel complementary matrixRight singular vector set of left null spaceAnd the right singular vector set is collectedSetting as a transmission beam forming matrix TBFM F of the ith user equipment in the p iteration_i ^(p)(ii) a The TBFMF of the ith user equipment is determined according to the convergence rule_i ^(p)Set as the precoding matrix F of the ith user equipment_i。

On the other handThe embodiment of the invention provides a linear precoding device for a communication system, which comprises a precoding unit M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiBeing a natural number, the apparatus includes: a first setting module, configured to set an initial value of a receive beamforming matrix RBFM of a current subcarrier of the ith ue according to channel characteristics of the subcarrier related to the current subcarrierA first determining module for determining RBFM of the ith UE according to the p-1 iterationsDetermining an equivalent joint channel complementary matrix of the ith user equipment in the p iterationWherein p is a natural number; a second setting module for complementing the equivalent joint channel of the ith UE determined by the first determining moduleSingular value decomposition is carried out to obtain and form the equivalent joint channel complementary matrixRight singular vector set of left null spaceAnd the right singular vector set is collectedSet as the transmission beam forming matrix TBFMF of the ith user equipment in the p iteration_i ^(p)(ii) a A second determination module for determining the second according to the convergence ruleTBFM F of the ith user equipment set by the setting module_i ^(p)Determining a precoding matrix F of the ith user equipment_i。

Based on the above technical solution, the method and apparatus for linear precoding in a communication system according to the embodiments of the present invention set the initial value of the receive beamforming matrix of the current subcarrier according to the channel characteristics of the subcarrier related to the current subcarrier of the user equipment, so that the precoding matrix can be quickly and simply obtained, the throughput of the system can be increased, the computational complexity of the system can be reduced, and the number of antennas at the transmitting end and the receiving end is not limited, thereby comprehensively improving the performance of the system.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a method for linear precoding for a communication system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an application scenario of a method for linear precoding of a communication system according to an embodiment of the present invention.

FIG. 3 is a schematic block diagram of a simulation performed by a method according to an embodiment of the present invention.

Fig. 4 is a graph comparing complementary cumulative distribution functions of system throughput in accordance with an embodiment of the present invention.

FIG. 5 is a graph comparing complementary cumulative distribution functions for iteration counts according to an embodiment of the present invention.

Fig. 6 is a graph comparing complementary cumulative distribution functions of effective snr according to an embodiment of the present invention.

Fig. 7A and 7B are graphs comparing probability of modulation coding scheme selection according to embodiments of the present invention.

Fig. 8 is a graph comparing complementary cumulative distribution functions of system throughput according to another embodiment of the present invention.

Fig. 9A and 9B are graphs comparing probability of modulation coding scheme selection according to another embodiment of the present invention.

Fig. 10 is a schematic block diagram of an apparatus for linear precoding for a communication system according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

It should be understood that the solution of the present invention can be applied to various communication systems, such as: a Global System for Mobile communications (GSM) System, a Code Division Multiple Access (CDMA) System, a Wideband Code Division Multiple Access (WCDMA) System, a General Packet Radio Service (GPRS), a Long Term Evolution (LTE) System, a Frequency Division Duplex (FDD) System, a Time Division Duplex (TDD), a Universal Mobile Telecommunications System (UMTS), a Wireless Local Area Network (WLAN) System, and the like.

It should also be understood that, in the embodiment of the present invention, a User Equipment (User Equipment, abbreviated as "UE") may be referred to as a Terminal (Terminal), a Mobile Station (Mobile Station, abbreviated as "MS"), a Mobile Terminal (Mobile Terminal), a Station (Station), and the like, and the User Equipment may communicate with one or more core networks via a Radio Access Network (RAN), for example, the User Equipment may be a Mobile phone (or referred to as a "cellular" phone), a computer with a Mobile Terminal, and the like, for example, the User Equipment may also be a portable, pocket, hand-held, computer-included, or vehicle-mounted Mobile device, and they exchange words and/or data with the RAN.

In this embodiment of the present invention, the base Station may be a base Station in GSM or CDMA (BTS), a base Station in WCDMA (NodeB, NB for short), an evolved Node B in LTE (ENB or e-NodeB), or an Access Point in WLAN (Access Point, AP for short), which is not limited in this invention. For convenience of description, the following embodiments will be described by taking a base station NB and a user equipment UE as examples.

Fig. 1 shows a schematic flow diagram of a method 100 for linear precoding for a communication system according to an embodiment of the invention. As shown in FIG. 1, the method 100 is applied to a communication system including a base station having M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiBeing a natural number, the method 100 includes:

s110, setting an initial value of a Receive Beamforming matrix (RBFM) of the current subcarrier according to a channel characteristic of a subcarrier related to the current subcarrier of the ith ue

S120, according to the RBFM of the ith user equipment in the p-1 iterationDetermining an equivalent joint channel complementary matrix of the ith user equipment in the p iterationWherein p is a natural number;

s130, complementing the matrix through the equivalent joint channel of the ith user equipmentSingular value decomposition is carried out to obtain and form the equivalent joint channel complementary matrixRight singular vector set of left null spaceAnd the right singular vector set is collectedSetting as a transmission Beamforming matrix (TBFM) F of the ith UE in the p-th iteration_i ^(p)；

S140, according to the convergence rule, the TBFMF of the ith user equipment is determined_i ^(p)Set as the precoding matrix F of the ith user equipment_i。

In the method of the embodiment of the invention, for a specific user equipment, an initial value of a receiving beam forming matrix RBFM of a current subcarrier of the user equipment is firstly set, an equivalent combined channel complementary matrix of the user equipment in a first iteration process can be calculated according to the initial value of the RBFM, Singular Value Decomposition (SVD) is carried out on the equivalent combined channel complementary matrix, a transmitting beam forming matrix TBFM of the user equipment in the first iteration process can be obtained, if a convergence rule is not met after the first iteration process, the next iteration process is carried out until the convergence rule is met, and the transmitting beam forming matrix TBFM obtained in the iteration process is set as a precoding matrix of the user equipment. It should be appreciated that the receive beamforming matrix RBFM that needs to be used during the next iteration may be calculated before or after determining whether the convergence rule was satisfied during the previous iteration. Because the initial value of the RBFM adopted by the method considers the channel characteristics of the sub-carrier related to the current sub-carrier, namely the channel correlation of the related sub-carrier is considered, the iteration process can be accelerated, the iteration times are reduced, and the complexity of the method is simplified.

Therefore, in the linear precoding method for a communication system according to the embodiment of the present invention, the initial value of the receive beamforming matrix of the current subcarrier is set according to the channel characteristic of the subcarrier related to the current subcarrier of the user equipment, so that the precoding matrix can be quickly and simply obtained, the throughput of the system can be increased, the computational complexity of the system can be reduced, the number of antennas at the transmitting end and the receiving end is not limited, and the performance of the system can be comprehensively improved.

The following describes the method for linear precoding used in a communication system according to an embodiment of the present invention in detail with reference to the application scenario shown in fig. 2.

As shown in FIG. 2, a communication system applied to the embodiment of the present invention includes a communication device having M_TA base station of transmitting antennas, and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA total number of receiving antennas M for the K user equipments_RWherein i is 1, 2, …, K, M_T、K、M_RiIs a natural number, M_RCan be determined by the following equation (1):

<math> <mrow> <msub> <mi>M</mi> <mi>R</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>M</mi> <mi>Ri</mi> </msub> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

it should be understood that the communication system may include a base station having an M_TA transmitting antenna, the communication system may also comprise two or more base stations having a total of M_TA transmitting antenna.

As shown in FIG. 2, the transmission signal of the ith UE is defined as r_iVector x of-dimensions_iWherein r is_iIs the number of data streams sent to the ith user equipment. The K vectors can be represented by the following equation (2):

wherein, <math> <mrow> <mi>r</mi> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>r</mi> <mi>i</mi> </msub> <mo>.</mo> </mrow> </math>

the joint precoding matrix F may be represented by the following equation (3):

wherein, F_iIs a precoding matrix of the ith user equipment and satisfies

Assuming that the communication system is an Orthogonal Frequency-division multiplexing (OFDM) system, the channel matrix H of the ith user at a given Frequency and a given time_iSatisfy the requirement ofAnd the joint channel matrix of K user equipments can be determined by the following equation (4):

it should be understood that the embodiment of the present invention is only described by taking the OFDM system as an example, but the present invention is not limited thereto, and the embodiment of the present invention may also be applied to other communication systems.

On the user equipment side, the Joint Block-diagonaldecoding matrix (Joint Block-diagonaldecoding matrix) may be determined by the following equation (5):

wherein, the decoding matrix D of the ith user equipment_iSatisfy the requirement of

Thus, the joint reception vector y can be determined by the following equation (6):

y＝D·(H·F·x+n) (6)

wherein,reception vector y of ith user equipment_iSatisfy the requirement ofn_iIs the zero mean additive white gaussian noise of the receiving antenna of the ith user equipment.

How to obtain the precoding matrix F of the ith user equipment will be described in detail below with reference to the method shown in FIG. 1_i。

In S110, setting an initial value of a receive beamforming matrix RBFM of a current subcarrier of the ith ue according to channel characteristics of the subcarrier related to the current subcarrierOptionally, if the current subcarrier is not the first subcarrier of the ith UE, the initial value of RBFM of the current subcarrier is setAnd setting the RBFM used for determining the precoding matrix of the subcarrier adjacent to the current subcarrier. If the current sub-carrier is the first sub-carrier of the ith UE, the initial value of RBFM is setMay be arranged as a random matrix.

In the embodiment of the invention, if the current subcarrier is not the first subcarrier of the ith user equipment, the initial value of the RBFM of the current subcarrier is setAn RBFM may be set to determine a precoding matrix for any subcarrier having a correlation with the current subcarrier. For example, the initial value of RBFM of the current sub-carrierAn RBFM configured to determine a precoding matrix for one or more subcarriers spaced apart from a current subcarrier. Preferably, the initial value of the RBFM of the current subcarrier is setAnd setting the RBFM used for determining the precoding matrix of the subcarrier adjacent to the current subcarrier.

In the embodiment of the present invention, it should be understood that, if the precoding matrix of a subcarrier can be determined after p iterations, the RBFM used for determining the precoding matrix of the subcarrier adjacent to the current subcarrier includes the reception beamforming matrix RBFM calculated by the p-th iteration, that is, the RBFM calculated according to the determined precoding matrix, and also includes the reception beamforming matrix RBFM calculated by the p-1-th iteration, and other RBFMs calculated by the p-2 previous iterations. Preferably, in the embodiment of the present invention, the RBFM used for determining the precoding matrix of the subcarrier adjacent to the current subcarrier is a reception beamforming matrix RBFM calculated according to the determined precoding matrix, that is, the reception beamforming matrix RBFM calculated in the p-th iteration.

It should be understood that the sub-carriers adjacent to the current sub-carrier refer to sub-carriers that are located before and after the current sub-carrier in frequency.

Although the research on the channel model D in 802.11ac shows that there is a large frequency selective fading in the 802.11ac system, there is a certain correlation between the channel characteristics of the subcarriers. Therefore, in the method of the embodiment of the invention, the initial value of the receiving beam forming matrix RBFM is set in consideration of the correlation of channels between adjacent carriers, thereby greatly reducing the iteration times before the convergence rule is satisfied, reducing the complexity of the method and comprehensively improving the performance of the system.

In S120, according to the RBFM of the ith user equipment in the p-1 th iterationDetermining an equivalent joint channel complementary matrix of the ith user equipment in the p iterationEquivalent joint channel complement matrixDetermined by the following equation (7):

${\tilde{H}}_{\mathrm{ei}}^{\left(p\right)}={\left[\begin{array}{cccccc}{H}_{e1}^{{\left(p\right)}^T}& ...& H_{e(i-1)}^{{\left(p\right)}^T}& H_{e(i+1)}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T---\left(7\right)$

wherein the equivalent channel matrix of the ith user equipment in the p-th iterationH_iAnd p is a natural number, and is the channel matrix of the ith user equipment. I.e. for the ith user equipment, from the equivalent joint channel matrix in the p-th iterationThe equivalent channel matrix of the ith user equipment is removed, so that the equivalent combined channel complementary matrix of the user equipment in the p iteration can be obtainedEquivalent joint channel matrixDetermined by the following equation (8):

$H_e^{\left(p\right)}=\left[\begin{array}{c}{H}_{e1}^{\left(p\right)}\\ .\\ .\\ .\\ H_{\mathrm{ei}}^{\left(p\right)}\\ .\\ .\\ .\\ H_{\mathrm{eK}}^{\left(p\right)}\end{array}\right]---\left(8\right)$

it should be understood that the channel matrix H of the ith user equipment_iThe channel estimation method can be obtained by feeding back the user equipment to the base station according to a standard protocol, or directly estimating the channel estimation result at a transmitting end of the user equipment, for example, in a TDD system, the user equipment directly estimates a channel matrix of the user equipment according to a channel state.

In the embodiment of the present invention, optionally, if the ith ue employs a Minimum Mean-Square-Error (MMSE) receiver, the receive beamforming matrix RBFM of the ith ue isDetermined by the following equation (9):

<math> <mrow> <msubsup> <mi>D</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>H</mi> <mi>i</mi> </msub> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <msup> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mi>H</mi> </msup> </msup> <msubsup> <mi>H</mi> <mi>i</mi> <mi>H</mi> </msubsup> <mo>+</mo> <msup> <msub> <mi>&sigma;</mi> <mi>n</mi> </msub> <mn>2</mn> </msup> <msub> <mi>I</mi> <msub> <mi>M</mi> <mi>Ri</mi> </msub> </msub> <mo>)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>9</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein, F_i ^(p-1)A transmit beamforming matrix TBFM, sigma for the ith user equipment in the p-1 iteration_n ²In order to receive the noise power of the antenna,is M_Ri×M_RiA dimension unit matrix;

optionally, if the ith user equipment adopts the maximal ratio combining MRC receiver, the RBFM of the ith user equipmentDetermined by the following equation (10):

$D_i^{(p-1)}=H_i{F_i}^{(p-1)}---\left(10\right)$

it should be appreciated that the RBFM of the ith UE in the p-1 th iterationThe calculation may be performed before or after determining whether the p-1 th iteration satisfies the convergence condition in the p-1 th iteration process, or may be performed according to a result of the p-1 th iteration process in the p-1 th iteration process, which is not limited in the embodiment of the present invention.

In S130, the equivalent joint channel complementary matrix of the ith user equipmentPerforming singular value decomposition, i.e. equivalent joint channel complement matrixCan be determined by the following equation (11):

<math> <mrow> <msubsup> <mover> <mi>H</mi> <mo>~</mo> </mover> <mi>ei</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msubsup> <mover> <mi>U</mi> <mo>~</mo> </mover> <mi>ei</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msubsup> <msubsup> <mover> <mi>&Sigma;</mi> <mo>~</mo> </mover> <mi>ei</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msubsup> <msup> <mfenced open='[' close=']'> <mtable> <mtr> <mtd> <msubsup> <mover> <mi>V</mi> <mo>~</mo> </mover> <mi>ei</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </mtd> <mtd> <msubsup> <mover> <mi>V</mi> <mo>~</mo> </mover> <mi>ei</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>,</mo> <mn>0</mn> <mo>)</mo> </mrow> </msubsup> </mtd> </mtr> </mtable> </mfenced> <mi>H</mi> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>11</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein, it is toU matrix obtained after singular value decompositionThe obtained column is called a left singular vector, and the obtained V matrixThe columns are called right singular vectors, where,is shown as frontThe number of right singular vectors,show thatA right singular vector, thisThe right singular vectors form an equivalent joint channel complementary matrixLeft null space.

By pairsSingular value decomposition is carried out to obtain a complementary matrix forming the equivalent joint channelRight singular vector set of left null spaceAnd the right singular vector set is collectedSetting as a transmission beam forming matrix TBFM F of the ith user equipment in the p iteration_i ^(p)I.e. the transmit beamforming matrix TBFM F_i ^(p)Can be determined by the following equation (12):

${F_i}^{\left(p\right)}={\tilde{V}}_{\mathrm{ei}}^{(p,0)}---\left(12\right)$

in S140, if the convergence rule is satisfied, the TBFMF of the ith ue is determined_i ^(p)Set as the precoding matrix F of the ith user equipment_i(ii) a If the convergence rule is not yet satisfied, the next iteration is performed.

In the embodiment of the invention, the convergence rule comprises whether user interference, TBFM change, iteration times and the like meet corresponding threshold values. Specifically, if the user interference is less than or equal to the first threshold 1, it may be determined that the convergence rule is satisfied. For example, if the user interferes withIt may be determined that the convergence rule is satisfied and the user interferes withCan be determined by the following equation (13):

$\mathrm{MUI}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)={\left|\right|\mathrm{off}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)\left|\right|}_F^2---\left(13\right)$

wherein, theTo representAll off-diagonal elements. It should be appreciated that user interferenceCan also take the value as pairOther norms are taken and are not limited to taking the F norm.

If the TBFM change is less than or equal to the second threshold of 2, then it may be determined that the convergence rule is satisfied. For example, if TBFM changesIt may be determined that the convergence rule is satisfied. Similarly, F may be paired^(p)-F^(p-1)Other norms are taken and used for convergence determination.

If the number of iterations is less than or equal to the third threshold 3, it may be determined that the convergence rule is satisfied. For example, if the number of iterations p ≦ 3, it may be determined that the convergence rule is satisfied.

In an embodiment of the invention, optionally, the convergence rule comprises multi-user interferenceTBFM variationAnd the number of iterations p is less than or equal to 3. I.e. whether the iteration process is terminated can be determined according to a number of convergence rules.

In the embodiment of the present invention, optionally, the number M of the transmitting antennas of the communication system_TLess than or equal to the total number M of receiving antennas of the K user equipments_R. It should be understood that the method according to embodiments of the present invention may also be applied to the number M of transmit antennas_TThe total number M of receiving antennas of the user equipment is larger than the K_RThe scene (2). In the embodiment of the present invention, optionally, the communication system includes a multi-user MU multiple-input multiple-output MIMO multi-carrier system.

It should be understood that the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiment of the present invention.

Therefore, in the linear precoding method for a communication system according to the embodiment of the present invention, the initial value of the receive beamforming matrix of the current subcarrier is set according to the channel characteristic of the subcarrier related to the current subcarrier of the user equipment, so that the precoding matrix can be quickly and simply obtained, the throughput of the system can be increased, the computational complexity of the system can be reduced, the number of antennas at the transmitting end and the receiving end is not limited, and the performance of the system can be comprehensively improved.

The following describes in detail the advantageous effects of the embodiments of the present invention with reference to fig. 3 to 9B.

To further illustrate the performance of the method in the examples of the present invention, the results of the simulation using MATLAB are given below. The simulation configuration and parameter setting are performed according to the specification of scenario 2 in IEEE 802.11 ac. In the following, a description of scenario 2 is first given:

scene # 2: point-to-multipoint link testing

(a)5GHz frequency band, not higher than 80MHz channel bandwidth;

(b) a task group ac (TGac) Access Point (AP for short) is used as a source, and at least 2 TGac terminals (STAs) are used as destination receivers (sinks);

(c) physical layer (PHY) channel model: a model D;

(d) the position of the AP is fixed as follows: (0,0), the positions of the two terminals STA may be (0,10) and (10, 0).

Because of the high complexity and long running time of the Link simulation, the performance of the proposed method is described by using the System throughput, and in addition, in order to consider the flexibility of the simulation, the System level simulation is performed by using the Link-to-System (abbreviated as "L2S") interface.

Fig. 3 shows a block diagram of a system level simulation performed by the method according to the embodiment of the present invention, wherein the actual simulation flow is indicated by the dashed box part, and the preparation stage of the simulation is shown by the part above the dashed box. First, parameters related to OFDM, channel parameters strongly related to a scene, user equipment and antennas, parameters related to a protocol, parameters of simulation, and the like are set. Data for link-to-system Mapping (Mapping) is loaded for processing according to the corresponding parameter settings. For each independent simulation, there is a new channel realization associated with the channel and antenna parameters. The scheduling method determines the user group sum of the same frequency served at the same time. Then, the parameter setting stage also initializes the real simulation flow, and the precoding and decoding matrixes are calculated under the assumption of complete channel information (CSI) by applying different precoding algorithms. Next, an equivalent channel matrix and an equivalent noise variance matrix are obtained, and a Signal-to-Interference-plus-noise ratio (SINR) is calculated on each subcarrier on all spatial streams. The method of link-to-system Mapping herein employs an Exponential Effective SNR Mapping (Signal-to-Noise Ratio) Mapping, referred to as "EESM". Through link-to-system mapping, the throughput of the user equipment and the throughput of the system under different precoding methods can be calculated.

For the system level simulation of scenario 2, it is assumed that an 80MHz transmission channel bandwidth is used, and the simulation selects a 5GHz band, 5170 MHz-5270 MHz, with a center frequency of 5.21 GHz; generating a channel model D by adopting IEEE 802.11 ac; it is assumed that good Channel State Information (Channel State Information at the Transmitter, abbreviated as "CSIT") and Channel State Information (Channel State Information at the Receiver, abbreviated as "CSIR") at the transmitting end can be obtained. Since only PHY performance is evaluated in the current simulation, considering the overhead portion brought when a Physical Layer Protocol data Unit (PPDU) is transmitted, the Physical Layer Service data Unit (PSDU) size in the simulation is set to 5000B (bytes). The distance between the base station and the user is already present at the time of channel matrix generation. In the simulation parameter setting phase, it has been considered that the maximum number of spatial streams summed over multiple user equipments during multi-user transmission is 8. In addition, considering that each link needs to support MIMO in the study, the maximum number of transmit and receive antennas should be 8. The transmission power was set to 30dBm, and the noise power density was calculated assuming a room temperature of 290K. A Packet Error Rate (PER) threshold for each Modulation and Coding Scheme (MCS) handover in link adaptation is set to 0.01.

For a communication system with 8 transmit antennas and 4 user equipments, each user equipment has 4 receive antennas, the number of data streams transmitted to each user equipment is 2, i.e. K is 4, M_T＝8，M_Ri＝4，r_iFig. 4 shows a Complementary Cumulative Distribution Function (CCDF) comparison graph of system throughput according to an embodiment of the present invention, where i is 1, 2, …, K, and the total number of spatial streams is 8. In fig. 4, curve a is a CCDF graph of system throughput obtained by the method according to the embodiment of the present invention, and curve B isAccording to the CCDF graph of the system throughput obtained by the method in the prior art, it can be known from fig. 4 that the method of the embodiment of the present invention can obtain a larger system throughput and has a better performance.

Fig. 5 shows a graph comparing complementary cumulative distribution functions of the number of iterations in the communication system as shown in fig. 4, in accordance with an embodiment of the present invention. Wherein, the curve a is a CCDF graph of the number of iterations obtained according to the method of the embodiment of the present invention, and the curve B is a CCDF graph of the number of iterations obtained according to the method of the prior art, and it can be known from fig. 5 that the number of iterations of the method of the embodiment of the present invention is less, and the computational complexity is lower.

Fig. 6 is a graph showing a comparison of complementary cumulative distribution functions of effective sinrs of each ue according to an embodiment of the present invention, wherein curve a is a curve obtained according to an embodiment of the present invention, and curve B is a curve obtained according to a method of the prior art. Fig. 7A shows a probability plot for modulation coding scheme selection according to an embodiment of the present invention for each user equipment, and fig. 7B shows a probability plot for modulation coding scheme selection according to the prior art for each user equipment. It can be seen from the figure that the method according to the embodiment of the present invention always selects the highest MCS for communication.

Fig. 8 shows a complementary cumulative distribution function comparison graph of system throughput according to another embodiment of the present invention. Wherein curves a1 and a2 are graphs of complementary cumulative distribution functions of system throughput at PSDU sizes of 50000B and 5000B, respectively, according to embodiments of the present invention; curves B1 and B2 are complementary cumulative distribution function graphs of system throughput at PSDU sizes of 50000B and 5000B, respectively, according to the prior art. As can be seen from fig. 8, by increasing the size of the PSDU, the system throughput can be further increased, and when the PDSU size is 50000B, even the system throughput of 2.7GHz can be obtained according to the embodiment of the present invention, and the system performance is better.

Fig. 9A and 9B show probability graphs of modulation and coding scheme selection according to an embodiment of the present invention and the prior art when the PDSU size is 50000B, respectively, and it can be known that even when the PSDU is increased to 50000B, the probability of selecting MCS 9 by using the method of the embodiment of the present invention is still high, about 90%, and the complexity can be further reduced.

Therefore, in the linear precoding method for a communication system according to the embodiment of the present invention, the initial value of the receive beamforming matrix of the current subcarrier is set according to the channel characteristic of the subcarrier related to the current subcarrier of the user equipment, so that the precoding matrix can be quickly and simply obtained, the throughput of the system can be increased, the computational complexity of the system can be reduced, the number of antennas at the transmitting end and the receiving end is not limited, and the performance of the system can be comprehensively improved.

The method for linear precoding for a communication system according to an embodiment of the present invention is described in detail above with reference to fig. 1 to 9B, and the apparatus for linear precoding for a communication system according to an embodiment of the present invention is described in detail below with reference to fig. 10.

Fig. 10 shows a schematic block diagram of an apparatus 500 for linear precoding for communication systems according to an embodiment of the present invention. The communication system comprises a communication module having M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiAs shown in fig. 10, the apparatus 500 includes:

a first setting module 510, configured to set an initial value of a receive beamforming matrix RBFM of a current subcarrier of the ith ue according to channel characteristics of the subcarrier related to the current subcarrier

A first determining module 520, configured to determine the RBFM of the ith UE according to the p-1 th iterationDetermining an equivalent joint channel complementary matrix of the ith user equipment in the p iterationWherein p is a natural number;

a second setting module 530, configured to complement the equivalent joint channel of the ith ue determined by the first determining moduleSingular value decomposition is carried out to obtain and form the equivalent joint channel complementary matrixRight singular vector set of left null spaceAnd the right singular vector set is collectedSet as the transmission beam forming matrix TBFMF of the ith user equipment in the p iteration_i ^(p)；

A second determining module 540, configured to set the TBFM F of the ith user equipment set by the second setting module according to a convergence rule_i ^(p)Determining a precoding matrix F of the ith user equipment_i。

The linear precoding device for the communication system of the embodiment of the invention can quickly and simply obtain the precoding matrix, increase the throughput of the system, reduce the computational complexity of the system and have no limit on the number of antennas at the transmitting end and the receiving end by setting the initial value of the receiving beamforming matrix of the current subcarrier according to the channel characteristic of the subcarrier related to the current subcarrier of the user equipment, thereby comprehensively improving the performance of the system.

In the embodiment of the present invention, it is,optionally, if the ith ue employs a minimum mean square error MMSE receiver, then the RBFM of the ith ue is determined to be the minimum mean square error MMSE receiverDetermined by the following equation:

<math> <mrow> <msubsup> <mi>D</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>H</mi> <mi>i</mi> </msub> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <msup> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mi>H</mi> </msup> </msup> <msubsup> <mi>H</mi> <mi>i</mi> <mi>H</mi> </msubsup> <mo>+</mo> <msup> <msub> <mi>&sigma;</mi> <mi>n</mi> </msub> <mn>2</mn> </msup> <msub> <mi>I</mi> <msub> <mi>M</mi> <mi>Ri</mi> </msub> </msub> <mo>)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <msup> <msub> <mi>F</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <mo>,</mo> </mrow> </math>

wherein, F_i ^(p-1)For TBFM, sigma of the ith user equipment in the p-1 iteration_n ²In order to receive the noise power of the antenna,is M_Ri×M_RiA dimension unit matrix;

if the ith user equipment adopts the maximum ratio combining MRC receiver, the RBFM of the ith user equipmentDetermined by the following equation:

$D_i^{(p-1)}=H_i{F_i}^{(p-1)}.$

in the embodiment of the present invention, optionally, the first setting module is specifically configured to: if the current sub-carrier is not the first sub-carrier of the ith user equipment, the initial value of the RBFM of the current sub-carrier is determinedAnd setting the RBFM used for determining the precoding matrix of the subcarrier adjacent to the current subcarrier.

In an embodiment of the invention, optionally, the equivalent joint channel complementary matrixDetermined by the following equation:

${\tilde{H}}_{\mathrm{ei}}^{\left(p\right)}={\left[\begin{array}{cccccc}{H}_{e1}^{{\left(p\right)}^T}& ...& H_{e(i-1)}^{{\left(p\right)}^T}& H_{e(i+1)}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein, the equivalent channel matrix of the ith user equipment in the p iterationH_iIs the channel matrix of the ith user equipment.

In an embodiment of the invention, optionally, the convergence rule comprises multi-user interferenceTBFM variationAnd the number of iterations p is less than or equal to 3, the multi-user interferenceDetermined by the following equation:

$\mathrm{MUI}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)={\left|\right|\mathrm{off}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)\left|\right|}_F^2$

$H_e^{\left(p\right)}={\left[\begin{array}{ccccc}{H}_{e1}^{{\left(p\right)}^T}& ...& H_{\mathrm{ei}}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein, theTo representAll the elements on the non-diagonal, 1, 2, 3 are the first threshold, the second threshold and the third threshold, respectively.

In the embodiment of the present invention, optionally, the number M of the transmitting antennas of the communication system_TLess than or equal to the total number M of receiving antennas of the K user equipments_RWherein the total number of the receiving antennas is M_RDetermined by the following equation:

<math> <mrow> <msub> <mi>M</mi> <mi>R</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>M</mi> <mi>Ri</mi> </msub> <mo>.</mo> </mrow> </math>

in the embodiment of the present invention, optionally, the communication system includes a MU MIMO multi-carrier system.

The above and other operations and/or functions of each module in the apparatus 500 according to the embodiment of the present invention are respectively for implementing corresponding flows of each method in fig. 1 to fig. 9, and are not described herein again for brevity.

The linear precoding device for the communication system of the embodiment of the invention can quickly and simply obtain the precoding matrix, increase the throughput of the system, reduce the computational complexity of the system and have no limit on the number of antennas at the transmitting end and the receiving end by setting the initial value of the receiving beamforming matrix of the current subcarrier according to the channel characteristic of the subcarrier related to the current subcarrier of the user equipment, thereby comprehensively improving the performance of the system.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (14)

1. A method for linear precoding in a communication system, the communication system comprising M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiIs a positive integer, the method comprises:

setting a receiving beam forming matrix RBFM of the current subcarrier according to the channel characteristics of the subcarrier related to the current subcarrier of the ith user equipmentInitial value

According to the RBFM of the ith user equipment in the p-1 iterationDetermining an equivalent joint channel complement matrix of the ith user equipment in the p-th iterationWherein p is a natural number;

by complementing the equivalent joint channel of the ith user equipment with a matrixPerforming singular value decomposition to obtain the equivalent joint channel complement matrixRight singular vector set of left null spaceAnd combining the right singular vectorsSetting as a transmit beamforming matrix TBFM for the ith user equipment in the p-th iteration

The TBFM of the ith user equipment is determined according to a convergence ruleSetting as precoding matrix F of the ith user equipment_i。

2. The method of claim 1, wherein if the ith UE employs a Minimum Mean Square Error (MMSE) receiver, the RBFM of the ith UE is determinedDetermined by the following equation:

<math> <mrow> <msubsup> <mi>D</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>H</mi> <mi>i</mi> </msub> <msubsup> <mi>F</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msubsup> <mi>F</mi> <mi>i</mi> <msup> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mi>H</mi> </msup> </msubsup> <msubsup> <mi>H</mi> <mi>i</mi> <mi>H</mi> </msubsup> <mo>+</mo> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> <msub> <mi>I</mi> <msub> <mi>M</mi> <mi>Ri</mi> </msub> </msub> <mo>)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <msubsup> <mi>F</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mtext>,</mtext> </mrow> </math>

wherein,for the TBFM of the ith user equipment in the p-1 th iteration,in order to receive the noise power of the antenna,is M_Ri×M_RiA dimension unit matrix;

if the ith user equipment adopts the maximum ratio combining MRC receiver, the RBFM of the ith user equipmentDetermined by the following equation:

$D_i^{(p-1)}=H_i{F}_i^{(p-1)}.$

3. the method of claim 1, wherein the initial value of the RBFM for the current sub-carrier is set according to the channel characteristics of the sub-carrier associated with the current sub-carrierThe method comprises the following steps:

if the current sub-carrier is not the ith user equipmentThe initial value of RBFM of the current sub-carrier is obtainedAn RBFM configured to determine a precoding matrix for subcarriers adjacent to the current subcarrier.

4. The method of claim 1, wherein the equivalent joint channel complement matrixDetermined by the following equation:

${\tilde{H}}_{\mathrm{ei}}^{\left(p\right)}={\left[\begin{array}{cccccc}{H}_{e1}^{{\left(p\right)}^T}& ...& H_{e(i-1)}^{{\left(p\right)}^T}& H_{e(i+1)}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein the equivalent channel matrix of the ith user equipment in the p-th iterationH_iIs the channel matrix of the ith user equipment.

5. The method of claim 1, wherein the convergence rule comprises multiuser interference <math> <mrow> <mi>MUI</mi> <mrow> <mo>(</mo> <msubsup> <mi>H</mi> <mi>e</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msubsup> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msup> <mo>)</mo> </mrow> <mo>&le;</mo> <mi>&epsiv;</mi> <mn>1</mn> <mo>,</mo> </mrow> </math> TBFM variation <math> <mrow> <msubsup> <mrow> <mo>|</mo> <mo>|</mo> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msup> <mo>-</mo> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <mo>|</mo> <mo>|</mo> </mrow> <mi>F</mi> <mn>2</mn> </msubsup> <mo>&le;</mo> <mi>&epsiv;</mi> <mn>2</mn> </mrow> </math> And the number of iterations p is less than or equal to 3, the multi-user interferenceDetermined by the following equation:

$\mathrm{MUI}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)={\left|\right|\mathrm{off}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)\left|\right|}_F^2$

$H_e^{\left(p\right)}={\left[\begin{array}{ccccc}{H}_e^{{\left(p\right)}^T}& ...& H_{\mathrm{ei}}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein, theTo representAll the elements on the non-diagonal, 1, 2, 3 are the first threshold, the second threshold and the third threshold, respectively.

6. Method according to any of claims 1 to 5, characterized in that the number M of transmitting antennas of the communication system_TLess than or equal to the total number M of receiving antennas of the K user equipments_RWherein the total number of receiving antennas is M_RDetermined by the following equation:

<math> <mrow> <msub> <mi>M</mi> <mi>R</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>M</mi> <mi>Ri</mi> </msub> <mo>.</mo> </mrow> </math>

7. the method according to any of claims 1 to 5, wherein the communication system comprises a multi-user MU multiple-input multiple-output, MIMO, multi-carrier system.

8. An apparatus for linear precoding in a communication system, the communication system comprising a precoding matrix having M_TA base station with transmitting antennas and K user equipments, wherein the ith user equipment in the K user equipments has M_RiA receiving antenna, i ═ 1, 2, …, K, where M_T、K、M_RiIs a positive integer, the apparatus comprising:

a first setting module, configured to set an initial value of a receive beamforming matrix RBFM of a current subcarrier of the ith ue according to a channel characteristic of the subcarrier related to the current subcarrier

A first determining module for determining RBFM of the ith UE according to the p-1 th iterationDetermining an equivalent joint channel complement matrix of the ith user equipment in the p-th iterationWherein p is a natural number;

a second setting module, configured to complement the equivalent joint channel of the ith ue determined by the first determining modulePerforming singular value decomposition to obtain the equivalent joint channel complement matrixRight singular vector set of left null spaceAnd combining the right singular vectorsSetting as a transmit beamforming matrix TBFM for the ith user equipment in the p-th iteration

Second determinationA setting module, configured to set the TBFM of the ith ue set by the second setting module according to a convergence ruleDetermining a precoding matrix F for the ith user equipment_i。

9. The apparatus of claim 8, wherein the RBFM of the ith user equipment is determined if the ith user equipment employs a Minimum Mean Square Error (MMSE) receiverDetermined by the following equation:

<math> <mrow> <msubsup> <mi>D</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msup> <mrow> <mo>(</mo> <msub> <mi>H</mi> <mi>i</mi> </msub> <msubsup> <mi>F</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <msubsup> <mi>F</mi> <mi>i</mi> <msup> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mi>H</mi> </msup> </msubsup> <msubsup> <mi>H</mi> <mi>i</mi> <mi>H</mi> </msubsup> <mo>+</mo> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> <msub> <mi>I</mi> <msub> <mi>M</mi> <mi>Ri</mi> </msub> </msub> <mo>)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msub> <mi>H</mi> <mi>i</mi> </msub> <msubsup> <mi>F</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mtext>,</mtext> </mrow> </math>

wherein,for the TBFM of the ith user equipment in the p-1 th iteration,in order to receive the noise power of the antenna,is M_Ri×M_RiA dimension unit matrix;

if the ith user equipment adopts the maximum ratio combining MRC receiver, the RBFM of the ith user equipmentDetermined by the following equation:

$D_i^{(p-1)}=H_i{F}_i^{(p-1)}.$

10. the apparatus of claim 8, wherein the first setting module is specifically configured to:

if the current subcarrier is not the first subcarrier of the ith user equipment, the initial value of the RBFM of the current subcarrier is determinedAn RBFM configured to determine a precoding matrix for subcarriers adjacent to the current subcarrier.

11. The apparatus of claim 8, wherein the equivalent joint channel complement matrixDetermined by the following equation:

${\tilde{H}}_{\mathrm{ei}}^{\left(p\right)}={\left[\begin{array}{cccccc}{H}_{e1}^{{\left(p\right)}^T}& ...& H_{e(i-1)}^{{\left(p\right)}^T}& H_{e(i+1)}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein the equivalent channel matrix of the ith user equipment in the p-th iterationH_iIs the channel matrix of the ith user equipment.

12. The apparatus of claim 8, wherein the convergence rule comprises multiuser interference <math> <mrow> <mi>MUI</mi> <mrow> <mo>(</mo> <msubsup> <mi>H</mi> <mi>e</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msubsup> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msup> <mo>)</mo> </mrow> <mo>&le;</mo> <mi>&epsiv;</mi> <mn>1</mn> <mo>,</mo> </mrow> </math> TBFM variation <math> <mrow> <msubsup> <mrow> <mo>|</mo> <mo>|</mo> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>)</mo> </mrow> </msup> <mo>-</mo> <msup> <mi>F</mi> <mrow> <mo>(</mo> <mi>p</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <mo>|</mo> <mo>|</mo> </mrow> <mi>F</mi> <mn>2</mn> </msubsup> <mo>&le;</mo> <mi>&epsiv;</mi> <mn>2</mn> </mrow> </math> And the number of iterations p is less than or equal to 3, the multi-user interferenceDetermined by the following equation:

$\mathrm{MUI}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)={\left|\right|\mathrm{off}\left(H_e^{\left(p\right)}{F}^{\left(p\right)}\right)\left|\right|}_F^2$

$H_e^{\left(p\right)}={\left[\begin{array}{ccccc}{H}_e^{{\left(p\right)}^T}& ...& H_{\mathrm{ei}}^{{\left(p\right)}^T}& ...& H_{\mathrm{eK}}^{{\left(p\right)}^T}\end{array}\right]}^T,$

wherein, theTo representAll the elements on the non-diagonal, 1, 2, 3 are the first threshold, the second threshold and the third threshold, respectively.

13. The apparatus according to any of claims 8 to 12, wherein the number M of transmit antennas of the communication system_TLess than or equal to the total number M of receiving antennas of the K user equipments_RWherein the total number of receiving antennas is M_RDetermined by the following equation:

<math> <mrow> <msub> <mi>M</mi> <mi>R</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>M</mi> <mi>Ri</mi> </msub> <mo>.</mo> </mrow> </math>

14. an apparatus according to any of claims 8-12, wherein the communication system comprises a MU MIMO multi-carrier system.