JP2015139223A - Method for feedback and exchange of channel state information, apparatus and base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve precise estimation of interference from a cooperative cell; to complete accurate update of channel quality indication (CQI); to avoid the occurrence of a case when the CQI of UE is estimated high or low; to achieve precise user scheduling; and to improve system performance.SOLUTION: A base station determines the degree of matching between the receiver of UE (user equipment), which is a service target of the self-station, and a cooperative cell channel (101); and determines interference power received in the UE from the cooperative cell, on the basis of the degree of matching between the UE receiver and the cooperative cell channel (102); and determines signal power received in the UE on the basis of the CSI which is fed back from the UE (103); and then updates the CQI on the basis of the interference power and signal power received in the UE from the cooperative cell, to select a modulation coding system and perform user scheduling for the UE, on the basis of the updated CQI (104).

Description

  The present invention relates to wireless communication technology, and in particular, to a channel state information (CSI) feedback and exchange method, apparatus, and base station.

  In coordinated multipoint (CoMP) transmission, for example, in coordinated multipoint-coordinated scheduling / coordinated beamforming (CoMP-CS / CB) transmission, the base station (eNB) receives channel state information fed back from the user equipment (UE). The channel quality indication (CQI) needs to be updated based on the CQI, and then user scheduling needs to be performed based on the updated CQI.

  However, the base station has a very limited CSI that can be known from the UE, and cannot accurately estimate the interference power from other cooperating cells in the transmission coordinating group, and therefore cannot accurately update the CQI of the UE. . That is, since the base station often estimates the CQI of the UE high or low, accurate user scheduling cannot be realized. For example, when the CQI of a UE is estimated to be high, user scheduling is performed based on the highly estimated CQI, and then data is transmitted to the UE using a high modulation and coding scheme (MCS). Become. This often causes data transmission failures, causes very high block error rates (BLER), and causes a large amount of data retransmission, greatly reducing network throughput. In addition, when the UE CQI is estimated to be low, user scheduling is performed based on the low estimated CQI, and then data transmission to the UE is performed using a low modulation coding scheme (MCS). Become. This reduces transmission efficiency and causes resource waste.

  In order to solve the above problems, in an embodiment of the present invention, feedback of channel state information is provided so as to improve the system performance by avoiding the occurrence when the UE channel quality indication is estimated to be high or low. And an exchange method, apparatus, and base station.

  In the method for feedback and exchange of channel state information provided in an embodiment of the present invention, a base station determines a matching degree between a receiver of a UE that is a service target of the local station and a channel of a cooperative cell, and the base station Determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell, and the base station determines based on the channel state information fed back from the UE. , Determine the signal power received by the UE, the base station updates the channel quality indication based on the interference power and signal power from the coordinated cell received by the UE, and the updated channel quality indication And performing modulation coding scheme selection and user scheduling for the UE.

Here, the base station determines the degree of matching between the receiver of the UE that is the service target of the local station and the channel of the cooperative cell when the UE is in the eigenbeam formation of the serving cell and the cooperative cell of the local station. The matching reception directions U _S and U _C are determined, and the UE calculates a matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the determined U _S and U _C , and the UE The matching degree parameter between the receiver of the local station and the channel of the cooperative cell is reported to the base station of the serving cell of the local station via the air interface, and the base station is reported from the UE that is the service target of the local station. Receiving a matching degree parameter between the receiver of the UE and the channel of the cooperative cell.

Based on the determined U _S and U _C , the UE calculates a matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the determined U _S and U _C. Te, and calculates the matching degree parameter U _S ^H U _C of the channel of a coordinated cell with the receiver of the mobile station, said method comprising, where the operator () ^H denotes a conjugate transpose operation of a matrix.

The UE reports the matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the serving cell of the local station via the air interface. the matching degree parameter U _S ^H U _C of the channel is quantized to report matching degree between the channel of the receiver and coordinated cell of the own station after quantization in the base station of the serving cell of its own station, or, the UE Feedback the matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the local serving cell based on the code book.

を算出する、ことを含み、ここで、Ｐ_ｔは協調セルの総送信電力であり、ｒ_ｃはランク総数であり、Ｐ_Ｎは雑音とサービングセルおよび協調セル以外の干渉電力との和であり、Σ_ｃは協調セルの基地局の固有ビーム形成方向のチャネルゲインであり、演算子（）^Ｈは行列の共役転置演算を表す。 Alternatively, the UE, based on the determined U _S and U _C, to calculate a matching degree parameter a receiver and a channel of a coordinated cell of its own station, the UE has been determined U _S and U _C Based on the matching parameter between the receiver of the local station and the channel of the cooperative cell

Calculating a, said method comprising, wherein, P _t is the total transmission power of the coordinated cell, r _c is the rank total number, P _N is the sum of the noise and the serving cell and the interference power of non-coordinated cell, Σ _c is the channel gain in the eigen beam forming direction of the base station of the cooperative cell, and the operator () ^H represents the conjugate transpose operation of the matrix.

によって、前記ＵＥの受ける協調セルからの干渉電力を決定する、ことを含み、ここで、Ｖ_Ｃは協調セルの基地局の固有ビーム形成方向を表し、Ｗ_Ｃは協調セルの基地局のプリコーディング行列を表す。 In this case, the base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

Determining the interference power from the cooperating cell received by the UE, where V _C represents the eigen beamforming direction of the base station of the cooperating cell, and W _C is the precoding of the base station of the cooperating cell. Represents a matrix.

を算出する、ことを含み、ここで、Ｐ_ｔは協調セルの総送信電力であり、ｒ_ｃはランク総数であり、Ｐ_Ｎは雑音とサービングセルおよび協調セル以外の干渉電力との和であり、Ｈ_Ｃは協調セルの基地局から前記ＵＥへのチャネルであり、演算子（）^Ｈは行列の共役転置演算を表す。 Alternatively, the UE calculates the matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the determined U _S and U _C , because the UE determines the determined U _S and U Based on _C , the matching degree parameter between the receiver of the local station and the channel of the cooperative cell

Calculating a, said method comprising, wherein, P _t is the total transmission power of the coordinated cell, r _c is the rank total number, P _N is the sum of the noise and the serving cell and the interference power of non-coordinated cell, H _C is the channel to the UE from the base station of the coordinated cell, operator () ^H denotes a conjugate transpose operation of a matrix.

によって、前記ＵＥの受ける協調セルからの干渉電力を決定する、ことを含み、ここで、Ｗ_Ｃは協調セルの基地局のプリコーディング行列を表す。 In this case, the base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

By determining the interference power from the cooperative cells subject of the UE, said method comprising, wherein, W _C represents the precoding matrix of a base station of a coordinated cell.

  The UE reports the matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the serving cell of the local station via the air interface. Including the step of quantizing the matching degree parameter with the other channel and feeding back the degree of matching between the quantized receiver and the channel of the cooperative cell to the base station of the serving cell of the own station.

The base station determines the degree of matching between the receiver of the UE that is the service target of the own station and the channel of the cooperative cell. The sounding reference signal (SRS) transmitted from the UE by the base station of the serving cell of the UE based on, by estimating the uplink channel, to obtain a matching reception direction U _S at specific beamforming of the base station of the cell, the base station of another coordinated cell inside the coordinated group, sent from the UE SRS The base station of the base station of this cell obtains the matching reception direction U _C at the time of eigenbeam formation of the base station of this cell by estimating the uplink channel, and the base station of the cooperative cell feedback of the matching receive direction U _C during specific beamforming base station to the base station of the serving cell of the UE, the base station of the serving cell of the UE, Another receives a matching reception direction U _C during specific beamforming base station of the other coordinated cell fed back from the base station of the coordinated cell regulating the group, the base station of the serving cell of the UE, the mobile station calculating a service target UE receiver matching degree parameter U _S ^H U _C of the channel of the coordinated cell, said method comprising, where the operator () ^H denotes a conjugate transpose operation of a matrix.

Base station coordinated cells, via a backhaul between base stations, that a matching receive direction U _C during specific beamforming base station of the present cell is fed back to the base station of the serving cell of the UE, the coordinated cell The base station of this cell quantizes the matching reception direction parameter at the time of eigenbeam formation of the base station of this cell, and sets the matching reception direction at the time of eigenbeam formation of the base station of this cell after quantization to the base station of the serving cell of the UE Or the base station of the cooperative cell feeds back the matching reception direction at the time of eigenbeam formation of the base station of this cell to the base station of the serving cell of the UE based on the code book.

The base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

  In the method, after the base station determines the matching degree between the receiver of the UE that is the service target of the local station and the channel of the cooperative cell, the base station determines the service of the local station determined by the sliding window processing method. It further includes processing for the matching degree between the receiver of the target UE and the channel of the cooperative cell.

  The embodiments of the present invention also provide an apparatus for feedback and exchange of channel state information. This apparatus is based on matching degree determining means for determining a matching degree between a receiver of a UE that is a service target of the own station and a channel of a cooperative cell, and a matching degree between the receiver of the UE and a channel of the cooperative cell. Interference power determining means for determining interference power from the coordinated cell received by the UE, signal power determining means for determining signal power received by the UE based on channel state information fed back from the UE, Based on the interference power and signal power from the cooperative cell received by the UE, the channel quality indication is updated, and based on the updated channel quality indication, the UE selects the modulation and coding scheme and the user CQI update means for performing scheduling.

  Here, the matching degree determination means includes a matching degree receiving module that receives a matching degree parameter between the receiver of the UE and the channel of the cooperative cell reported from the UE via the air interface.

  Alternatively, the matching degree determining means is configured to estimate a channel between the cell base station and the UE based on the reference signal, and from the estimated channel, at the time of eigenbeam formation of the base station of the cell. Matching reception direction determining module that extracts a matching reception direction and a matching reception direction that feeds back the matching reception direction at the time of eigenbeam formation of the base station of this cell to the base station of the serving cell of the UE via a backhaul between the base stations A feedback module, a matching reception direction receiving module for receiving a matching reception direction at the time of eigenbeam formation of the base station of the other cooperative cell fed back from the base station of the other cooperative cell in the cooperative group, and a base of this cell The matching reception direction during eigenbeam formation of the station and the base station of the cooperative cell Based on the matching reception direction at the time of beam forming includes a matching calculation module for calculating a matching level parameter and channel coordinated cell and the UE receiver is the service object of the own station.

  In addition, in the embodiments of the present invention, a base station is also disclosed. This base station performs channel reconfiguration based on the channel state information reported from the UE, and the channel between the base station of this cell and the UE and between the base station of each cooperative cell and the UE. Channel reconfiguring means for obtaining a channel, precoding calculating means for calculating a precoding matrix of the present cell based on a channel between the base station and the UE of the present cell output from the channel reconfiguring means, A device for feedback and exchange of channel state information.

  In an embodiment of the present invention, before performing CQI update, the base station first determines the matching degree between the UE receiver and the channel of the coordinated cell, and the UE receiver and the channel of the coordinated cell By determining the interference power from the coordinated cell received by the UE based on the matching degree of the UE, accurate estimation of interference from the coordinated cell is realized, and further, the CQI update is completed accurately and the UE is supported. It is possible to avoid the occurrence when the CQI to be estimated is high or low, to realize accurate scheduling of the user, and to improve the system performance.

4 is a flowchart of a method for feedback and exchange of channel state information in an embodiment of the present invention. It is a figure which shows the internal structure of the apparatus of the feedback and exchange of channel state information in the Example of this invention. It is a figure which shows the internal structure of the base station in the Example of this invention.

  In order to further clarify the objects, solutions and merits of the present invention, the present invention will be described in more detail with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

  When the base station updates the CQI based on the CSI fed back from the UE, first, based on the CSI fed back from a UE within the coverage of the base station and the precoding matrix of the coordinated cell, The UE performs inter-cell interference power estimation and signal power estimation, and then performs CQI update of the UE based on the estimated inter-cell interference power and signal power corresponding to the UE. Since the base station has a very limited CSI that can be known from the UE, the base station does not accurately estimate the interference from each cell in the coordination group received by the UE. That is, the estimation to the inter-cell interference power corresponding to the UE by the base station is not accurate. As a result, the UE CQI cannot be accurately updated, and the UE CQI is often estimated to be high or low.

  For this reason, the embodiments of the present invention provide a method for feedback and exchange of channel state information so as to effectively avoid the occurrence when the CQI is estimated to be high or low. In this method, before updating the CQI, the base station first determines the degree of matching between the UE receiver and the channel of the cooperative cell, and the degree of matching between the UE receiver and the channel of the cooperative cell. By determining the interference power from the cooperative cell based on the above, it is possible to achieve accurate estimation of interference from the cooperative cell and to complete the accurate update of CQI.

  Specifically, FIG. 1 shows a flowchart of a method for feedback and exchange of channel state information in an embodiment of the present invention. As shown in FIG. 1, this method mainly includes a step 101 in which a base station determines a matching degree between a receiver of a UE that is a service target of the own station and a channel of a cooperative cell, and the base station Step 102 for determining interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell, and the base station based on the channel state information fed back from the UE Step 103 for determining the signal power received by the UE, and the base station updates the channel quality indication based on the interference power and the signal power from the cooperative cell received by the UE, and the updated channel And a step 104 of performing modulation coding scheme selection and user scheduling for the UE based on the quality indication.

Next, what is the degree of matching between the UE receiver and the channel of the cooperative cell will be described in detail. In an embodiment of the present invention, the channel from the base station of the serving cell of a UE to the UE is H _S, the channel from the base station of a coordinated cell with the cooperative group to the UE is assumed to be H _C. By performing singular value decomposition on the channels H _S and H _C , the following formulas 1 and 2 can be obtained.
[Formula 1]
_{H S = U S Σ S V} S H
[Formula 2]
_{H C = U C Σ C V} C H

Here, U _S and U _C represent matching reception directions at the time of eigenbeam formation of the serving cell base station and the coordinated cell base station, respectively, and Σ _S and Σ _C represent the serving cell base station and the coordinated cell, respectively. Where V _S and V _C represent the eigen beamforming directions of the serving cell base station and the cooperating cell base station, respectively, and the operator () ^H is the matrix Represents a conjugate transpose operation.

As described above, U _S represents a matching reception direction at the time of eigenbeam formation of the serving cell base station, that is, a matching reception direction of the UE receiver, and U _C represents eigenbeam formation of the base station of the cooperative cell. Indicates the matching reception direction at the time. Thus, the parameter U _S ^H U _C may represent a matching degree between the channel of the receiver and coordinated cell of UE, i.e., called matching degree between the channel of the receiver and coordinated cell of the UE.

To be noted, the parameter U _S ^H U _C is only a preferred example of the matching degree between the channel of the receiver and coordinated cell of the UE, may represent a matching degree between the channel of the receiver and coordinated cell of UE Any other possible parameter can be used as a matching degree parameter between the UE receiver and the channel of the coordinated cell.

  Next, the method in which the base station in step 101 determines the degree of matching between the receiver of the UE that is the service target of the local station and the channel of the cooperative cell will be described in detail.

Method 1: In this method, the base station may determine the degree of matching between the receiver of the UE that is the service target of the base station and the channel of the cooperative cell by the following steps. In Step 1011, the UE determines matching reception directions U _S and U _C when eigenbeam formation is performed for the serving cell and the cooperative cell of the local station. Specifically, the UE first transmits each cell to its own station based on a measurement reference signal transmitted from a cell (including a serving cell and a cooperative cell), for example, a channel state information reference signal (CSI-RS). An estimation may be performed on the channel, and then processing (eg, singular value decomposition) may be performed on the estimated channel. Thereby, it is possible to obtain the matching reception directions U _S and U _C at the time of eigenbeam formation of the serving cell and the cooperative cell of the local station. In step 1012, UE, based on the determined _{U S} and _{U C,} and calculates the matching degree parameter _U ^S H _{U C} of the channel of a coordinated cell with the receiver of the own station. In step 1013, UE via an air interface (Air Interface), reports the degree of matching parameters _U ^S H _{U C} of the channel of a coordinated cell with the receiver of the mobile station, to the base station of the serving cell of the own station. In step 1014, the base station of the serving cell receives the matching degree parameter U _S ^H U _C of the channel of a coordinated cell with UE receiver reported by the UE is a service target of its own station.

In practical application, in step 1013, UE is in two ways described below, reports the degree of matching parameters U _S ^H U _C of the channel of a coordinated cell with the receiver of the mobile station, to the base station of the serving cell of the mobile station May be.

(1) UE is the degree of matching parameters U _S ^H U _C of the channel of a coordinated cell with the receiver of the mobile station quantizes the own matching degree between the channel of the receiver and coordinated cell of the own station after quantization Report to the serving cell base station. For example, N _r ² quantized values are obtained by quantization, and these N _r ² quantized values are reported to the serving cell base station via the air interface. Here, _Nr is the number of antennas of the receiver of the UE. In this case, assuming that _Nr is 2 and each value is quantized with 4 bits, the method needs to use 16 bits in the air interface.

(2) Based on the code book, the UE feeds back a matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the local serving cell. If the codebook contains 16 codewords, this method requires the use of 4 bits in the air interface. The reason is that if the codebook is composed of 2 ^N unitary matrices, the UE only feeds back the N bits, and the serving cell determines the matching degree parameter between the UE's receiver and the channel of the cooperative cell. You can get to know.

チャネル再構成によって得られた協調セルの基地局から前記ＵＥへのチャネルを表し、Ｗ_Ｃは、協調セルの基地局のプリコーディング行列を表す。 Then, in step 102, the base station of the serving cell, determined the degree of matching parameters U _S ^H U _C and channel receiver and coordinated cell of UE, according to Equation 3 below, from the cooperative cells subject of the UE Interference power can be determined.
[Formula 3]

From the base station of the resulting coordinated cell by channel reconfiguration represents a channel to the UE, W _C represents the precoding matrix of a base station of a coordinated cell.

を算出する。ここで、Ｐ_ｔは協調セルの総送信電力であり、ｒ_Ｃはランク総数であり、Ｐ_Ｎは雑音とサービングセルおよび協調セル以外の干渉電力との和である。ステップ１０１３Ａで、ＵＥは、エアインタフェースを介して、算出された自局の受信機と協調セルのチャネルとのマッチング度パラメータＡ_１を自局のサービングセルの基地局に報告する。ステップ１０１４Ａで、サービングセルの基地局は、自局のサービス対象であるＵＥから報告されたＵＥの受信機と協調セルのチャネルとのマッチング度パラメータＡ_１を受信する。 Method 2: In this method, the base station may determine the degree of matching between the receiver of the UE that is the service target of the base station and the channel of the cooperative cell by the following steps. In Step 1011, the UE determines matching reception directions U _S and U _C when eigenbeam formation is performed for the serving cell and the cooperative cell of the local station. In step 1012A, the UE determines the matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the determined U _S and U _C.

Is calculated. Here, P _t is the total transmission power of the cooperative cell, r _C is the total number of ranks, and _PN is the sum of noise and interference power other than the serving cell and the cooperative cell. In step 1013A, UE via the air interface and reports the degree of matching parameters A ₁ and the receiver of the calculated own station as a channel of a coordinated cell to the base station of the serving cell of the own station. In step 1014A, the base station of the serving cell receives the matching degree parameter A ₁ between the channel of a coordinated cell with UE receiver reported by the UE is a service target of its own station.

In actual application, in step 1013A, the UE performs matching parameters between the receiver of the local station and the channel of the cooperative cell by the following method.

に含まれるため、ＵＥから報告する必要がなくなる。つまり、実際に増加するオーバヘッドは、１６個のビットに達していない。 In this case, assuming that _Nr is 2 and each value is quantized with 4 bits, the method needs to use 16 bits in the air interface. However, in this method, the channel quality information of the coordinated cell includes the matching degree parameter between the receiver of the local station and the channel of the coordinated cell reported from the UE.

Therefore, it is not necessary to report from the UE. In other words, the overhead that actually increases does not reach 16 bits.

Next, in step 102, the serving cell base station determines the matching degree parameter between the UE receiver and the coordinated cell channel.

を算出する。ステップ１０１３Ｂで、ＵＥは、エアインタフェースを介して、算出された自局の受信機と協調セルのチャネルとのマッチング度パラメータＡ_２を自局のサービングセルの基地局に報告する。ステップ１０１４Ｂで、サービングセルの基地局は、自局のサービス対象であるＵＥから報告されたＵＥの受信機と協調セルのチャネルとのマッチング度パラメータＡ_２を受信する。 Method 3: In this method, the base station may determine the degree of matching between the receiver of the UE that is the service target of the local station and the channel of the cooperative cell by the following steps. In Step 1011, the UE determines matching reception directions U _S and U _C when eigenbeam formation is performed for the serving cell and the cooperative cell of the local station. In step 1012B, the UE determines the matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the determined U _S and U _C.

Is calculated. In step 1013B, UE via the air interface and reports the degree of matching parameters A ₂ with the receiver of the calculated own station as a channel of a coordinated cell to the base station of the serving cell of the own station. In step 1014B, the base station of the serving cell receives the matching degree parameter A ₂ of the channel of the receiver coordinated cell of UE reported from UE, a service object of the own station.

In an actual application, in step 1013B, the UE performs matching parameters between the receiver of the local station and the channel of the cooperative cell by the following method.

に含まれるため、ＵＥから報告する必要がなくなる。つまり、実際に増加するオーバヘッドは、３２個のビットに達していない。 Here, N _t is the number of transmission antennas of the serving cell base station. In this case, assuming _Nr is 2, _Nt is 4, and each value is quantized with 4 bits, the method needs to use 32 bits in the air interface. However, in this method, the channel quality information of the cooperative cell and the eigen beam forming direction information V _C of the base station of the cooperative cell are the matching degree parameters between the receiver of the local station and the channel of the cooperative cell reported from the UE.

Therefore, it is not necessary to report from the UE. In other words, the overhead that actually increases does not reach 32 bits.

Next, in step 102, the serving cell base station determines the matching degree parameter between the UE receiver and the coordinated cell channel.

Method 4: As an alternative to the above method, the base station may determine the degree of matching between the receiver of the UE that is the service target of the base station and the channel of the cooperative cell by the following steps. In step 1011C, the base station estimates the uplink channel based on the sounding reference signal transmitted from the UE, and then performs processing on the estimated channel, thereby performing eigenbeam forming of the base station of this cell. Get matching reception direction of time. To be noted, matching reception direction at the time of eigen-beamforming in the base station of the above-mentioned present cell is a U _S taking the UE of the present cell is a U _C taking the UE of another coordinated cell inside the coordinated group. In step 1012C, the base station of each cooperating cell sets the matching reception direction at the time of eigenbeam formation of the base station of this cell via the backhaul between base stations, for example, the X2 interface, to the base of the serving cell of the UE. Give feedback to the station. In Step 1013C, the base station receives the matching reception direction at the time of eigenbeam formation of the base station of the cooperative cell fed back from the base station of the other cooperative cell in the cooperative group. In step 1014C, the base station calculates a matching degree parameter U _S ^H U _C of the channel of a coordinated cell with the UE receiver is the service object of the own station.

  In an actual application, in step 1013C, the base station may feed back the matching reception direction at the time of eigenbeam formation of the local station to the base station of another cooperative cell in the cooperative group by the following two methods. .

(1) The base station quantizes the matching reception direction parameter at the time of eigenbeam formation of the local station, and obtains, for example, N _r ² quantized values, and these N _r ² values via backhaul The value after quantization is fed back to the base stations of other cooperative cells in the cooperative group. In this case, an _{N r} is 2, assuming for quantizing each value in 4 bits, the method requires the use of 16 bits in backhaul.

  (2) Based on the codebook, the base station of the cooperative cell feeds back the matching reception direction parameter at the time of its own eigenbeam formation to the base station of the serving cell. If the codebook contains 16 codewords, the method needs to use 4 bits in backhaul.

Then, in step 102, the base station of the serving cell, determined the degree of matching parameters U _S ^H U _C and channel receiver and coordinated cell of UE, according to Equation 3 above, from the cooperative cells subject of the UE Interference power can be determined.

  It should be noted that the number of each method above (eg, Method 1, Method 2, Method 3, and Method 4) is only for a clearer explanation of the different methods and is important for the method. It does not represent degree or superiority.

チャネル再構成によって得られたサービングセルの基地局から前記ＵＥへのチャネルを表し、Ｗ_Ｓはサービングセルの基地局のプリコーディング行列を表す。 In step 103, since the CQI information is included in the channel state information fed back from the UE, in this step, the signal power corresponding to the UE is directly determined based on the CQI information fed back from the UE. Also good. For example, the base station may calculate the signal power received by the UE according to Equation 6 below.
[Formula 6]

From the base station of the serving cell obtained by channel reconfiguration represents a channel to the UE, W _S denotes the precoding matrix of a base station of the serving cell.

  As to be described, since CQI information fed back from the UE does not consider interference from within the cooperation group, it is necessary to update the CQI in the present invention.

  In step 104 above, for a specific method for updating the CQI based on the interference power estimation value and signal power from the cooperative cell corresponding to the UE, the related proposal of 3GPP may be referred to.

  As can be seen from the above method, in the embodiment of the present invention, before the CQI is updated, the base station first determines the matching degree between the UE receiver and the channel of the coordinated cell, and receives the UE. By determining the interference power from the cooperative cell received by the UE based on the matching degree between the mobile station and the channel of the cooperative cell, accurate estimation of the interference power from the cooperative cell is achieved. It is possible to complete the update, avoid the occurrence when the CQI corresponding to the UE is estimated to be high or low, realize accurate scheduling of the user, and improve the system performance.

Further, in the above method, after the step 101, the base station further performs sliding so as to reduce the delay time dependency of the matching degree between the receiver of the UE being served by the local station and the channel of the cooperative cell. You may process with respect to the matching degree of the receiver of UE which is the service object of the determined own station, and the channel of a cooperation cell by the window processing method. In actual application, the base station may perform processing on the matching degree between the receiver of the UE that is the service target of the base station and the channel of the cooperative cell, for example, by a method as shown in the following Equation 7. Good.
[Formula 7]

  Corresponding to the above method, an embodiment 200 of the present invention also provides an apparatus 200 for feedback and exchange of channel state information. As shown in FIG. 2, the internal configuration mainly includes matching degree determination means 201 that determines the degree of matching between a UE receiver that is a service target of its own station and a channel of a cooperative cell, and the receiver of the UE. Interference power determining means 202 for determining the interference power from the cooperative cell received by the UE based on the matching degree between the UE and the channel of the cooperative cell, and reception by the UE based on the channel state information fed back from the UE The channel power instruction is updated based on the interference power and the signal power from the cooperative cell received by the UE, and based on the updated channel quality instruction. CQI updating means 204 that performs modulation coding scheme selection and user scheduling for the UE.

を受信するマッチング度受信モジュールを含む。 Here, corresponding to the method 1, method 2, or method 3 for determining the matching degree between the UE receiver and the channel of the coordinated cell, the matching degree determination means 201 is connected from the UE via the air interface. The degree of matching parameter between the reported UE receiver and the channel of the coordinated cell, e.g.

Including a matching degree receiving module.

If the matching degree parameter of the channel of a UE and the receiver coordinated cell reported by the UE is U _S ^H U _C, interference power determining means 202, according to Equation 3 above, from the cooperative cells subject of the UE The interference power may be determined.

干渉電力決定手段２０２は、上記の数式５によって、該ＵＥの受ける協調セルからの干渉電力を決定してもよい。 The matching degree parameter between the UE receiver and the channel of the cooperative cell reported from the UE is

The interference power determination unit 202 may determine the interference power from the cooperative cell received by the UE according to Equation 5 above.

Corresponding to the method 4 for determining the matching degree between the UE receiver and the channel of the coordinated cell, the matching degree determination unit 201 uses a reference signal (for example, downlink CSI-RS or uplink SRS). And a channel estimation module for estimating a channel between the cell base station and the UE, and a matching reception direction determination for extracting a matching reception direction at the time of eigenbeam formation of the base station of the cell from the estimated channel A matching reception direction feedback module that feeds back the matching reception direction at the time of eigenbeam formation of the base station of this cell to the base station of the serving cell of the UE via a backhaul between the base station, for example, the X2 interface, The base of the cell fed back from the base station of another cooperative cell in the group A matching reception direction receiving module for receiving the matching reception direction at the time of forming the eigen beam of the station, a matching reception direction at the time of forming the eigen beam of the base station of this cell, and a matching reception direction at the time of forming the eigen beam of the base station of the cooperative cell based on, including a matching calculation module for calculating the degree of matching parameters U _S ^H U _C of the channel of a coordinated cell with the UE receiver is the service object of the own station.

To be noted, matching reception direction at the time of eigen-beamforming in the base station of the above-mentioned present cell is a U _S taking the UE of the present cell is a U _C taking the UE of another coordinated cell inside the coordinated group. In this case, the interference power determination unit 202 may determine the interference power from the cooperative cell received by the UE according to Equation 3 above.

  As can be seen from the configuration of the channel state information feedback and exchange apparatus, in the embodiment of the present invention, the channel state information feedback and exchange apparatus first receives the UE receiver before updating the CQI. And determining the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell, Achieves accurate estimation of interference from the CQI, and also completes the accurate update of CQI, avoids the occurrence when the CQI corresponding to the UE is estimated to be high or low, and realizes accurate scheduling of users It becomes possible to improve the performance of the system.

本セルのプリコーディング行列Ｗ_Ｓを算出するプリコーディング算出手段３０２と、上記のようなチャネル状態情報のフィードバックおよび交換の装置２００と、を含む。 In addition, the embodiment of the present invention also discloses a base station using the above-described channel state information feedback and exchange method and apparatus.

It includes a precoding calculation means 302 for calculating a precoding matrix W _S of the cell, the device 200 of feedback and exchange of channel state information as described above, the.

  As described above, the base station according to the embodiment of the present invention first determines the matching degree between the UE receiver and the channel of the cooperative cell before updating the CQI, and cooperates with the UE receiver. By determining the interference power from the cooperative cell received by the UE based on the degree of matching with the channel of the cell, accurate estimation of interference from the cooperative cell is realized, and furthermore, the accurate update of CQI is completed. , It is possible to avoid occurrence when the CQI corresponding to the UE is estimated to be high or low, to realize accurate scheduling of the user, and to improve the system performance.

  The above are only preferred embodiments of the present invention and do not limit the protection scope of the present invention. Various modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present invention should all be included in the protection scope of the present invention.

200 Device for feedback and exchange of channel state information 201 Matching degree determination means 202 Interference power determination means 203 Signal power determination means 204 CQI update means 301 Channel reconfiguration means 302 Precoding calculation means

Claims (17)

A method of channel state information (CSI) feedback and exchange comprising:
The base station determines the matching degree between the receiver of the user equipment (UE) that is the service target of the own station and the channel of the cooperative cell,
The base station determines the interference power from the cooperative cell received by the UE based on the degree of matching between the receiver of the UE and the channel of the cooperative cell,
A base station determines signal power received at the UE based on channel state information fed back from the UE;
The base station updates the channel quality indication (CQI) based on the interference power and signal power from the coordinated cell received by the UE, and modulates the UE based on the updated channel quality indication. Select the encoding method and perform user scheduling.
A method comprising: The base station determines a matching degree between a receiver of a UE that is a service target of the local station and a channel of a cooperative cell,
The UE determines matching reception directions U _S and U _C at the time of eigenbeam formation of its serving cell and cooperative cell,
Based on the determined U _S and U _C , the UE calculates a matching degree parameter between the receiver of the local station and the channel of the cooperative cell,
The UE reports a matching degree parameter between the receiver of the local station and the channel of the cooperative cell via the air interface to the base station of the serving cell of the local station,
The base station receives a matching degree parameter between a UE receiver and a channel of a coordinated cell reported from a UE that is a service target of the own station;
The method according to claim 1. The UE, based on the determined U _S and U _C, to calculate a matching degree parameter of the channel of the receiver and coordinated cell of its own station, the UE, to the determined U _S and U _C based on, and calculates the matching degree parameter U _S ^H U _C of the channel of a coordinated cell with the receiver of the mobile station, said method comprising,
Here, the operator () ^H represents the conjugate transpose operation of the matrix,
The method according to claim 2. The UE reports the matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the serving cell of the local station via the air interface, because the UE cooperates with the receiver of the local station. the degree of matching parameters U _S ^H U _C of the channel of the cell is quantized to report matching degree between the channel of a coordinated cell with the receiver of the own station after quantization in the base station of the serving cell of its own station, or the The UE feeds back a matching degree parameter between the receiver of the local station and the channel of the cooperative cell based on the codebook to the base station of the serving cell of the local station,
The method according to claim 3. The UE, based on the determined U _S and U _C, to calculate a matching degree parameter of the channel of the receiver and coordinated cell of its own station, the UE, to the determined U _S and U _C Based on the matching degree parameter between the receiver of the local station and the channel of the cooperative cell

Calculating, including
Here, P _t is the total transmission power of the cooperative cell, r _C is the total number of ranks, _PN is the sum of noise and interference power other than the serving cell and the cooperative cell, and Σ _C is the base station of the cooperative cell The channel gain in the eigen beam forming direction of, and the operator () ^H represents the conjugate transpose operation of the matrix,
The method according to claim 2. The base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

Determining interference power from the coordinated cell received by the UE,
Where V _C represents the eigen beamforming direction of the base station of the cooperative cell, and W _C represents the precoding matrix of the base station of the cooperative cell.
6. The method of claim 5, wherein: The UE, based on the determined U _S and U _C, to calculate a matching degree parameter of the channel of the receiver and coordinated cell of its own station, the UE, to the determined U _S and U _C Based on the matching degree parameter between the receiver of the local station and the channel of the cooperative cell

Calculating, including
Here, P _t is the total transmission power of the cooperative cell, r _C is the total number of ranks, _PN is the sum of noise and interference power other than the serving cell and the cooperative cell, and _HC is the base station of the cooperative cell To the UE, and the operator () ^H represents the conjugate transpose operation of the matrix,
The method according to claim 2. The base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

Determining interference power from the coordinated cell received by the UE,
Here, W _C represents the precoding matrix of a base station of a coordinated cell,
The method according to claim 7. The UE reports the matching degree parameter between the receiver of the local station and the channel of the cooperative cell to the base station of the serving cell of the local station via the air interface, because the UE cooperates with the receiver of the local station. Including quantizing a matching degree parameter with a channel of a cell and feeding back a matching degree between a receiver of the local station after the quantization and a channel of a cooperative cell to a base station of the serving cell of the local station,
The method according to claim 5 or 7, characterized in that The base station determines a matching degree between a receiver of a UE that is a service target of the local station and a channel of a cooperative cell,
The resulting base station of the serving cell of the UE, based on the sounding reference signal transmitted from UE (SRS), by estimating the uplink channel, the matching receive direction U _S at specific beamforming of the base station of the cell ,
The base station of the other cooperative cell in the cooperative group estimates the uplink channel based on the SRS transmitted from the UE, thereby obtaining the matching reception direction U _C at the time of eigenbeam formation of the base station of this cell,
Base station coordinated cells, via a backhaul between base stations, the matching receive direction U _C during specific beamforming base station of the present cell is fed back to the base station of the serving cell of the UE,
The serving cell base station of the UE receives the matching reception direction U _C at the time of eigenbeam formation of the base station of the other cooperative cell fed back from the base station of the other cooperative cell in the cooperative group;
The base station of the serving cell of the UE calculates a matching degree parameter U _S ^H U _C of the channel of a coordinated cell with the UE receiver is the service object of the own station, it comprises,
Here, the operator () ^H represents the conjugate transpose operation of the matrix,
The method according to claim 1. The base station of the cooperative cell via a backhaul between base stations, that a matching receive direction U _C during specific beamforming base station of the present cell is fed back to the base station of the serving cell of the UE, the cooperative The base station of the cell quantizes the matching reception direction parameter when forming the eigen beam of the base station of the cell, and sets the matching reception direction when forming the eigen beam of the base station of the cell after quantization to the base of the serving cell of the UE. Or the base station of the cooperative cell feeds back the matching reception direction at the time of eigenbeam formation of the base station of this cell to the base station of the serving cell of the UE based on the code book. ,
The method according to claim 10. The base station determines the interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell.

W _C represents a precoding matrix of a base station of a coordinated cell,
11. A method according to claim 3 or 10, characterized in that After the base station determines the degree of matching between the receiver of the UE that is the service target of the local station and the channel of the cooperative cell, the base station determines the UE that is the service target of the local station determined by the sliding window processing method. Further comprising processing for the matching degree between the receiver of and the channel of the cooperative cell,
The method according to claim 1. A device for feedback and exchange of channel state information (CSI) comprising:
A matching degree determination means for determining a matching degree between a receiver of a user equipment (UE) that is a service target of the local station and a channel of a cooperative cell;
Interference power determining means for determining interference power from the cooperative cell received by the UE based on the matching degree between the receiver of the UE and the channel of the cooperative cell;
Signal power determining means for determining signal power received at the UE based on channel state information fed back from the UE;
The channel quality indication (CQI) is updated based on interference power and signal power from the cooperative cell received by the UE, and based on the updated channel quality indication, a modulation coding scheme is updated for the UE. CQI updating means for performing selection and user scheduling;
The apparatus characterized by including. The matching degree determination means includes a matching degree receiving module that receives a matching degree parameter between the receiver of the UE and the channel of the coordinated cell reported from the UE via the air interface.
The apparatus according to claim 14. The matching degree determining means includes
A channel estimation module for estimating a channel between the base station of the cell and the UE based on the reference signal;
A matching reception direction determination module that extracts a matching reception direction at the time of eigenbeam formation of the base station of this cell from the estimated channel;
A matching reception direction feedback module that feeds back a matching reception direction at the time of eigenbeam formation of the base station of this cell to the base station of the serving cell of the UE via a backhaul between the base stations;
A matching reception direction receiving module for receiving a matching reception direction at the time of eigenbeam formation of the base station of the other cooperative cell fed back from the base station of the other cooperative cell in the cooperative group;
Based on the matching reception direction at the time of eigenbeam formation of the base station of this cell and the matching reception direction at the time of eigenbeam formation of the base station of the coordinated cell, the UE receiver and the channel of the coordinated cell that are the services of its own A matching degree calculation module for calculating a matching degree parameter with
The apparatus of claim 14, comprising: A base station,
Based on the channel state information (CSI) reported from the user equipment (UE), channel reconfiguration is performed, the channel between the base station of this cell and the UE, and the base station and UE of each coordinated cell Channel reconstruction means for obtaining a channel between,
Precoding calculating means for calculating a precoding matrix of the present cell based on a channel between the base station of the present cell and the UE output from the channel reconfiguring means;
Apparatus for feedback and exchange of channel state information according to any one of claims 14 to 16,
A base station comprising:

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