JP6961599B2 - Multi-antenna transmission method, base station, and user terminal - Google Patents

Description

The present application relates to the field of communication, and particularly to a multi-antenna transmission method, a base station, and a user terminal.

In a wireless communication system, there are many users who want to communicate with a base station and receive services at the same time. In these scenarios, it is feasible to schedule multiple users at the same time by means of multi-user, multi-input, multi-output (MU-MIMO) transmission schemes. With the development of antenna technology, large-scale antenna array systems (AAS) are gradually being applied to base stations. Such a large AAS typically includes hundreds of antenna array elements (eg, 128, 256 or more). These array elements may be arranged in a plane and used as a plane array antenna. By installing AAS on the base station side, it becomes possible to provide wireless communication to a larger number of users at the same time.

When a large-scale AAS is used in a limited space on the base station side, the spatial correlation of the radio propagation channel becomes high, especially in a scenario in which users are densely distributed. In this case, in order to guarantee the system capacity of the wireless communication system, theoretically, multi-antenna transmission can be performed by a non-linear precoding method. However, the realization complexity of nonlinear precoding methods becomes unacceptable as the number of antennas increases. Therefore, in high spatial correlation scenarios, it is necessary to design a multi-antenna transmission method with low complexity.

The embodiments of the present application provide multi-antenna transmission methods, base stations, and user terminals that are applicable to high spatial correlation scenarios and that achieve both low computational complexity and system performance.

Specifically, the embodiment of the present application is realized as follows.
A multi-antenna transmission method applied to a base station that divides the antenna array into at least two antenna sub-arrays and receives each antenna based on a first uplink signal transmitted from the user terminal (UE). A transmitter correlation parameter indicating the spatial correlation between different transmitter radio propagation channels for each subarray is estimated, and a beam for the downlink reference signal is estimated for each antenna subarray based on the transmitter correlation parameter. performs the forming, a downlink reference signal after beam forming, by said antenna sub-array, transmitting to the UE, see contains that, the method comprising: receiving a beam selection information fed back from the UE, received beam By scheduling users based on the selection information and transmitting downlink control signaling to each scheduling user, each scheduling user triggers transmission of a second uplink signal to the base station, and the second uplink signal is transmitted. Further includes precoding the data for each scheduling user based on the above and transmitting the precoded data to each scheduling user, where the data for each scheduling user is based on the second uplink signal. Precoding is to estimate the downlink channel status information for each scheduling user based on the second uplink signal, and calculate the first precoding matrix from the downlink channel status information of all scheduling users. , The second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix, and the first precoding matrix and the second precoding matrix are calculated. The first precoding matrix is a linear precoding matrix used between the antenna subarrays, which comprises precoding the data for each scheduling user based on the above. The coding matrix is a non-linear precoding matrix used within the antenna subarray .

It is a base station and includes a processor and a memory connected to the processor, and the memory includes a plurality of division modules, a reception module, an estimation module, a beam forming module, and a transmission module. When the command module is stored and the command module is executed by the processor, the following processing is executed, the division module divides the antenna array into at least two antenna subarrays, and the reception module is a user terminal. Upon receiving the first uplink signal transmitted from (UE), the estimation module receives spatial correlation between different transmitting radio propagation channels for each antenna subarray based on the received first uplink signal. The transmitting side correlation parameter indicating the property is estimated, and the beam forming module performs beam forming on the downlink reference signal for each antenna subarray based on the transmitting side correlation parameter, and after beam forming. Obtaining a downlink reference signal, the transmitting module transmits the downlink reference signal after beam forming to the UE by a corresponding antenna subarray , where the receiving module further receives beam selection fed back from the UE. Upon receiving the information, the base station further comprises a scheduling module that schedules users based on the received beam selection information, which transmission module further transmits downlink control signaling to each scheduling user. Triggering to transmit a second uplink signal from each scheduling user to the base station, the receiving module further receives a second uplink signal transmitted from each scheduling user, and the base station receives. A precoding module that precodes the data for each scheduling user based on the second uplink signal is further provided, and the transmitting module further transmits the precoded data to each scheduling user, where The precoding module estimates the downlink channel status information for each scheduling user based on the second uplink signal, and calculates the first precoding matrix from the downlink channel status information of all scheduling users. , From the downlink channel state information for each scheduling user and the first precoding matrix, a second for each scheduling user. A precoding matrix is calculated, and data for each scheduling user is precoded based on the first precoding matrix and the second precoding matrix, where the first precoding matrix is an antenna. It is a linear precoding matrix used between the subarrays, and the second precoding matrix is a non-linear precoding matrix used within the antenna subarray .

A user terminal including a processor and a memory connected to the processor. A plurality of command modules including a transmission module and a reception module are stored in the memory, and the command module is the processor. When executed, the following processing is executed, and the transmitting module transmits the first uplink signal to the base station in which the antenna array is divided into at least two antenna subarrays, so that the base station receives the data. Based on the first uplink signal, a transmitting side correlation parameter indicating the spatial correlation between different transmitting side radio propagation channels for each antenna subarray is estimated, and the transmitting side correlation is estimated for each antenna subarray. Beam forming is performed on the downlink reference signal based on the sex parameter, and the downlink reference signal after beam forming is transmitted to the user terminal by the antenna subarray, and the receiving module is transmitted from the base station to the user terminal. receiving a downlink reference signal after beam forming, wherein the user terminal based on the downlink reference signal after the received beamforming, by selecting the beam, further comprising a selection module that generates a beam selection information The transmission module further feeds back the beam selection information to the base station so that the base station schedules the user based on the beam selection information, and the downlink control transmitted from the base station. In response to the signaling, a second uplink signal is transmitted to the base station, where the base station estimates downlink channel state information for each scheduling user based on the second uplink signal, and all The first precoding matrix is calculated from the downlink channel status information of the scheduling user, and the second precoding matrix for each scheduling user is calculated from the downlink channel status information for each scheduling user and the first precoding matrix. Is calculated, and the data of the user terminal is precoded twice based on the first precoding matrix and the second precoding matrix to obtain the precoded data. Further, the precoded data is received from the base station, where the first precoding matrix is a linear precoding matrix used between the antenna subarrays and the second precoding matrix is Used in antenna subarray It is a non-linear precoding matrix to be used .

A non-volatile computer-readable storage medium in which machine-readable commands are stored in the storage medium, and the machine-readable commands are transmitted from a user terminal (UE) that has received the antenna array divided into at least two antenna sub-arrays. Based on the first uplink signal, a transmitting side correlation parameter indicating the spatial correlation between different transmitting side radio propagation channels for each antenna subarray is estimated, and the transmitting side correlation is estimated for each antenna subarray. Beam forming is performed on the downlink reference signal based on the sex parameter, the downlink reference signal after beam forming is transmitted to the UE by the antenna subarray, and the beam selection information fed back from the UE is received. By scheduling users based on the received beam selection information and transmitting downlink control signaling to each scheduling user, each scheduling user triggers transmission of a second uplink signal to the base station, and the second uplink signal is transmitted. It can be executed by the processor to complete that the data for each scheduling user is precoded based on the uplink signal of 2 and the precoded data is transmitted to each scheduling user. Precoding the data for each scheduling user based on the uplink signal of 2 estimates the downlink channel status information for each scheduling user based on the second uplink signal, and the downlink channel of all scheduling users. A first precoding matrix is calculated from the state information, a second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix, and the first precoding matrix is calculated. Precoding the data for each scheduling user based on the precoding matrix of 1 and the second precoding matrix, wherein the first precoding matrix is used between the antenna subarrays. The second precoding matrix is a non-linear precoding matrix used in the antenna subarray .

As can be seen from the above-mentioned solutions, the multi-antenna transmission method, the base station, and the user terminal provided in the embodiments of the present application are received by dividing the antenna array into at least two antenna sub-arrays by the base station. The transmitting side correlation parameter for each antenna subarray is estimated based on the uplink signal transmitted from the UE, and beam forming is performed on the downlink reference signal for each antenna subarray based on the transmitting side correlation parameter. , BRS is transmitted to the UE by the antenna subarray. Compared to beamforming the entire antenna array in the prior art, computational complexity can be reduced, it can be applied to scenarios where AAS is used and users are densely distributed, and it has high spatial correlation. A multi-antenna transmission method that achieves both performance and complexity is provided for a certain scenario.

It is a schematic diagram of the flow of the method in which the base station side performs multi-antenna transmission in some examples of this application. It is a schematic diagram of the division of the antenna sub-array in some examples of this application. It is a schematic diagram of the division of the antenna sub-array in some other examples of this application. It is a schematic diagram of the division of the antenna sub-array in another part of Examples of this application. It is a schematic diagram of the division of the antenna sub-array in some other examples of this application. It is a schematic diagram of the flow of the method in which the base station side performs multi-antenna transmission in some other examples of this application. It is a schematic diagram of the signaling exchange of the multi-antenna transmission method in some examples of this application. It is a schematic diagram of the flow of the method in which the UE side performs multi-antenna transmission in a part of Examples of this application. It is a schematic diagram of the structure of the base station in some examples of this application. It is a schematic diagram of the configuration of the base station in some other examples of this application. It is a schematic diagram of the configuration of the user terminal in some examples of this application.

In order to further clarify the object, the solution, and the merit of the present invention, the present application will be described in more detail with reference to the drawings below with reference to examples.

FIG. 1 is a schematic diagram of a flow of a multi-antenna transmission method according to some examples of the present application. This method applies to base stations. As shown in FIG. 1, this method includes the following steps.

In step 101, the antenna array is divided into at least two antenna sub-arrays.

In some examples of the present application, there are a plurality of methods for dividing the antenna sub-array, but the method includes dividing the antenna array based on at least one of the configuration of the antenna array and the polarization direction of the antenna array element. For example, uniform division or non-uniform division may be performed based on the configuration of the antenna array. Alternatively, an antenna array element having a similar polarization direction is divided into one antenna sub-array based on the polarization direction of the antenna array element. Alternatively, the antenna array is divided uniformly or non-uniformly in consideration of the polarization direction of the antenna array element. Here, the number of antenna array elements included in each antenna sub-array may be the same or different.

Taking a two-dimensional antenna array as an example, FIG. 2a is a schematic diagram of division of an antenna sub-array according to an embodiment of the present application. Here, the antenna array 210 is uniformly divided into four antenna sub-arrays 211, 212, 213, and 214. Each antenna sub-array is a regular square antenna array, each containing four antenna array elements.

FIG. 2b is a schematic diagram of the division of the antenna subarray in another embodiment of the present application. Here, the antenna array 210 is uniformly divided into four antenna sub-arrays 221, 222, 223, and 224 in the lateral direction. Each antenna sub-array is a regular lateral strip of antenna array, each containing four antenna array elements.

FIG. 2c is a schematic diagram of the division of the antenna subarray in another embodiment of the present application. Here, the antenna array 210 is uniformly divided into four antenna sub-arrays 231, 232, 233, and 234 in the vertical direction. Each antenna sub-array is a regular longitudinal strip of antenna array, each containing four antenna array elements.

FIG. 3 is a schematic diagram of the division of the antenna subarray in another embodiment of the present application. Here, the polarization method of the antenna array element of the antenna array 300 includes two polarization methods, vertical polarization and horizontal polarization. According to these two polarization methods, the antenna array 300 is divided into antenna sub-arrays 310 and 320, which include 16 antenna array elements, respectively. Here, the antenna array elements of the antenna sub-array 310 are all vertically polarized, and the antenna array elements of the antenna sub-array 320 are all horizontally polarized.

The method of dividing the antenna sub-array described above is merely an example, and when specifically applied, the antenna array may be divided into antenna sub-arrays including a different number of antenna array elements. For example, the 16 antenna array elements included in the antenna array 210 are divided into antenna sub-arrays including eight, six, and two antenna array elements, respectively. Here, the shape of the antenna sub-array and the number of antenna array elements included therein will affect the direction and coverage of the formed beam.

In step 102, the transmitting side correlation parameter for each antenna subarray is estimated based on the received first uplink signal transmitted from the user terminal (UE).

In this step, the first uplink signal may be an uplink reference signal or another uplink signal, for example, uplink data or a control signal. The transmit-side correlation parameter indicates the spatial correlation between different transmit-side radio propagation channels. For example, the sender correlation parameter may be represented as a sender correlation matrix.

Taking the uplink reference signal as an example, the base station estimates the transmitting side correlation matrix for each antenna subarray based on the uplink reference signal transmitted from the UE. Specifically, the antenna array can be estimated from the uplink reference signal. The entire sender correlation matrix is calculated, the sender correlation matrices of all UEs are averaged to obtain an equivalent sender correlation matrix, and the diagonal sub-matrix of the equivalent sender correlation matrix is obtained. It includes determining as a transmitting side correlation matrix for each antenna subarray.

は、

となる。ここで、［ ］^Ｈは共役転置演算を表す。 In one embodiment, the first uplink signal is a periodic sounding reference signal (P-SRS), which is the uplink channel matrix H of the kth user based on the P-SRS transmitted by the kth user. _{Assuming that k} is estimated and the total number of users is K, the equivalent sender correlation matrix

teeth,

Will be. Here, [] ^H represents the conjugate transpose operation.

は、さらに、

と表されてもよい。ここで、ｌ番目のアンテナサブアレイの送信側相関性行列は、上記

の対角線におけるｌ番目のサブ行列Ｒ_ｌｌ（ｌ＝１，・・・，Ｌ）である。ｌ番目のアンテナサブアレイにｎ個のアンテナアレイ素子が含まれる場合、Ｒ_ｌｌはｎ＊ｎの正方行列である。 When the entire antenna array is divided into L antenna sub-arrays, the above equivalent transmitter correlation matrix

In addition

May be expressed as. Here, the transmitting side correlation matrix of the l-th antenna subarray is described above.

The l-th sub-matrix R _ll (l = 1, ..., L) on the diagonal line of. When the l-th antenna sub-array contains n antenna array elements, R _ll is a square matrix of n * n.

In step 103, beamforming is performed on the downlink reference signal based on the transmission side correlation parameter for each antenna subarray, and the downlink reference signal (BRS: beamformed reference signal) after beamforming is obtained by the antenna subarray. , Send to UE.

In this step, a unique parameter is calculated from the transmission side correlation parameter, and beamforming is performed on the downlink reference signal based on the unique parameter to obtain a BRS. Specifically, when the sender correlation parameter is a sender correlation matrix, the eigenvalues are the eigenvectors corresponding to the maximum eigenvalues of the sender correlation matrix and / or the next largest eigenvalues of the sender correlation matrix. It may be an eigenvector corresponding to.

のように、Ｒ_ｌｌに対して固有値分解（ＥＶＤ）を行う。ここで、Σは固有値対角行列であり、Ｑは固有ベクトル行列であり、［ ］^−１は逆行列を求める演算を表す。Ｒ_ｌｌがフルランクである場合、Σ＝ｄｉａｇ（λ_１，λ_２，・・・,λ_ｎ）は大きい順に並べられるｎ個の固有値λ_１，λ_２，・・・,λ_ｎを含み、固有値ベクトルＱ＝｛χ_１，χ_２，・・・，χ_ｎ｝は、相応のｎ個の固有ベクトルχ_１，χ_２，・・・，χ_ｎを含む。最大固有値λ_１に対応する固有ベクトルはχ_１であり、次大固有値λ_２に対応する固有ベクトルはχ_２である。 For example, for each antenna subarray l = 1, ..., L, the corresponding transmitter correlation matrix R _ll can be uniquely represented by the eigenvalues and eigenvectors.

Eigenvalue decomposition (EVD) is performed on _{R ll} as in. Here, Σ is an eigenvalue diagonal matrix, Q is an eigenvector matrix, and [] ^-1 represents an operation for finding an inverse matrix. When R _ll is full rank, Σ = diag (λ ₁ , λ ₂ , ..., λ _n ) contains n eigenvalues λ ₁ , λ ₂ , ..., λ _n arranged in descending order. The eigenvalue vector Q = {χ ₁ , χ ₂ , ..., χ _n } contains the corresponding n eigenvectors χ ₁ , χ ₂ , ..., χ _n . The eigenvector corresponding to the maximum eigenvalue λ _{1 is χ 1} , and the eigenvector corresponding to the next largest eigenvalue λ ₂ is χ ₂ .

There may be one or more eigenvectors for beamforming the downlink reference signal. For example, in the l-th antenna subarray, when beamforming is performed on the downlink reference signals s _{RS, l} using the eigenvector χ _{1 corresponding to the maximum eigenvalue λ 1} , the obtained BRS is y _{BRS, l} = χ. ₁ s _{RS, l} .

Alternatively, in the l-th antenna subarray, when beamforming is performed on the downlink reference signals s _{RS, l} using the eigenvector χ _{2 corresponding to the second-} order eigenvalue λ 2, the obtained BRS is y _{BRS, l} = χ ₂ s _{RS, l} .

Alternatively, when beamforming is performed on the downlink reference signals s _{RS, l} using these two eigenvectors χ ₁ and χ _{2 , y BRS, l} = χ ₁ s _{RS, l} and y _{BRS 2, l} = _Two BRSs of χ 2 s _{RS and l} are obtained and transmitted to the UE respectively. _{Alternatively, the} two obtained BRSs may be superposed such as y BRS, l = χ ₁ s _{RS, l} + χ ₂ s _{RS, l} , and the combined BRS may be transmitted to the UE.

Considering the compatibility of long-term evolution (LTE) systems when specifically applied, the downlink reference signal may be a cell-only reference signal (CRS) or a channel state indication reference signal (CSI-RS). good.

Multiple BRS transmitted by L antenna subarrays can be over time frequency resources by time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM), or cyclic shift (CS). May be multiplexed with.

In the embodiment shown in FIG. 1 above, the base station divides the antenna array into at least two antenna sub-arrays, and the transmitting side correlation parameter for each antenna sub-array is based on the received uplink signal transmitted from the UE. Is estimated, beamforming is performed on the downlink reference signal for each antenna sub-array based on the transmitting side correlation parameter, and the BRS is transmitted to the UE by the antenna sub-array. Compared to beamforming the entire antenna array in the prior art, computational complexity can be reduced, it can be applied to scenarios where AAS is used and users are densely distributed, and it has high spatial correlation. A multi-antenna transmission method that achieves both performance and complexity is provided for a certain scenario.

FIG. 4 is a schematic diagram of a flow of a method in which the base station side performs multi-antenna transmission in another embodiment of the present application. As shown in FIG. 4, in addition to the steps shown in FIG. 1, FIG. 4 further includes the following steps.

In step 104, the beam selection information fed back from the UE is received, and the user is scheduled based on the received beam selection information.

In this step, the beam selection information may be the beam identifier corresponding to the BRS selected by the UE, or the antenna subarray identifier selected by the UE. Here, the beam identifier may be the index of the beam, and the antenna sub-array identifier may be the index of the antenna sub-array.

Specifically, when the UE receives a plurality of BRS transmitted by the L antenna subarray on the base station side, the UE selects one or a plurality of BRS from the plurality of BRS, and the beam corresponding to the selected BRS is selected. Determine the index. If the UE knows in advance the correspondence between the antenna sub-array on the base station side and the beam, the UE determines the index of the antenna sub-array corresponding to the index of the beam based on the correspondence, and determines the index of the antenna sub-array. The index of may be transmitted to the base station as beam selection information. When the UE does not know the specific information of the antenna subarray on the base station side, the UE transmits the index of the beam corresponding to the selected BRS to the base station as the beam selection information.

The base station determines the antenna subarray selected by the UE based on the received beam selection information. When the beam selection information is an index of the beam corresponding to the BRS selected by the UE, the base station can map the antenna subarray selected by the UE depending on the correspondence between the antenna subarray and the beam. When the beam selection information is an index of the antenna sub-array selected by the UE, the base station can directly determine the antenna sub-array selected by the UE.

The method by which the base station schedules users is to group the UEs based on the determined antenna subarray selected by the UE to obtain the scheduling target UE group corresponding to each antenna subarray, and then each scheduling. For each target UE group, the scheduling user for transmitting data by the antenna subarray corresponding to the scheduling target UE group is determined. Here, one scheduling target UE group includes one or a plurality of UEs.

In one embodiment, when grouping users, they may be grouped simply based on user feedback. That is, the UEs that feed back the indexes of the same antenna subarray are made to belong to one scheduling target UE group without any adjustment. For example, there are K UEs, and for L antenna subarrays, UE1 feeds back that the index of the selected antenna subarray is 1, and UE2 has an index of 1 and the selected antenna subarray. Feedback that it is 2, UE3 feeds back that the index of the selected antenna subarray is 1 and 3, UE4 feeds back that the index of the selected antenna subarray is 1, and UE5 feeds back. , Feed back that the index of the selected antenna subarray is 1, ..., It is assumed that UEK feeds back that the index of the selected antenna subarray is L.

Then, the base station can obtain the results shown in Table 1. Here, there are five UEs that have selected the antenna subarray having an index of 1, and these five UEs belong to one group. For example, there are many users who are currently waiting to be scheduled within the coverage of the beam formed by the antenna subarray, such as a plurality of users having a conference in one conference room. Considering the scenario, these users simultaneously requested data services from the base station, and the base station determined that the indexes of the antenna subarrays selected by these users were all 1.

In other embodiments, the base station may group UEs based on the scheduling balance principle. That is, the number of scheduling target UEs assigned to each antenna subarray is balanced so that the number of UEs in all scheduling target UE groups is relatively close. For example, as shown in Table 2, when the index of the antenna subarray fed back from a large number of UEs is 1, the base station may appropriately adjust the scheduling target UEs divided into the same group among the antenna subarrays. good. For example, consider coordinating between antenna subarrays with close beams, leaving only a few UEs with multiple antenna subarrays selected in only one group. Compared to the results in Table 1 with no adjustments, UE4 and UE5 are assigned to the scheduled UE groups with corresponding indexes 2 and 3, respectively, with a corresponding index of 1 as shown in Table 2. UE3 is deleted from a certain scheduling target UE group, and UE3 is assigned only to the scheduling target UE group having a corresponding index of 3.

In addition to feeding back the index of the selected antenna subarray to the base station, if the UE also transmits the RSRP of the BRS received by the selected antenna subarray to the base station, the base station will perform on each UE. Users may be grouped with reference to the RSRP in the selected antenna subarray. For example, in the above scheduling balance principle, it is considered to leave only UEs whose RSRP is higher than a certain threshold in each scheduling target UE group so that the number of scheduling target UEs assigned to each antenna subarray is relatively close.

For each scheduling target UE group, the base station may determine one or more scheduling users from among them based on a predetermined scheduling metric. Here, the scheduling metric may be a geometric mean of UE throughput, a proportional fairness scheduling metric, or an improved proportional fairness scheduling metric.

In step 105, by transmitting downlink control signaling to each scheduling user, each scheduling user triggers transmission of a second uplink signal to the base station, and each scheduling user is based on the second uplink signal. Precode the data and send the precoded data to each scheduling user.

In this step, the second uplink signal may be an uplink reference signal such as an aperiodic sounding reference signal (A-SRS). The transmitted downlink control signaling is provided with an instruction bit for instructing the scheduling user to transmit an uplink reference signal. This triggers the scheduling user to send an uplink reference signal to the base station. The base station then performs channel estimation based on the received uplink reference signal and estimates downlink channel state information for the entire antenna array based on the channel reciprocity principle.

In the present application, since the entire antenna array is divided into a plurality of antenna sub-arrays and the spatial correlation of channels between the antenna sub-arrays is weak, a linear precoding algorithm may be used between the antenna sub-arrays. Thereby, good performance can be obtained. Also, inside the antenna subarray, a non-linear precoding algorithm is used to adapt to high spatial correlation. That is, each of the two precoding matrices is calculated and precoded by a cascade method.

Specifically, a linear precoding matrix is calculated by a linear precoding method from the downlink channel state information of all scheduling users, and this is used as the first precoding matrix. Next, a non-linear precoding matrix for each scheduling user is calculated from the estimated downlink channel state information and the linear precoding matrix by the non-linear precoding method, and this is used as the second precoding matrix. Then, the data for each scheduling user is precoded based on the linear precoding matrix and the non-linear precoding matrix.

との積

に対して、例えばＴＨＰアルゴリズムによって非線形プリコーディングを行って、非線形プリコーディング行列Ｖ_ｋを得る。さらに、ＰおよびＶ_ｋに基づいて、全てのユーザデータを２回プリコーディングして、プリコーディングされたデータを得る。 For example, linear precoding may use a zero forcing (ZF) or block diagonalization (BD) algorithm to obtain the linear precoding matrix P from the downlink channel state information of all scheduling users. Then, for each scheduling user in the antenna subarray, the linear precoding matrix P and the downlink channel matrix

Product with

On the other hand, for example, the nonlinear precoding is performed by the THP algorithm to obtain the _{nonlinear precoding matrix Vk.} Further, based on P and V _k , all user data is precoded twice to obtain the precoded data.

In one embodiment, when transmitting precoded data, the precoded data may be transmitted simultaneously to all scheduling users across the antenna array. In another embodiment, if each antenna subarray corresponds to one scheduling user group and each scheduling user group contains a plurality of scheduling users, different transmission time zones are set and one for each antenna subarray. Even if the transmission time zone is specified and then the antenna sub-array corresponding to the scheduling user transmits the precoded data in the specified transmission time zone, that is, the antenna sub-arrays are transmitted in a time-divided manner. good.

In the embodiment shown in FIG. 4, the base station receives the beam selection information fed back from the UE, schedules the user based on the received beam selection information, and determines the scheduling user for each antenna subarray. , Spatial correlation between scheduling user groups corresponding to different antenna subarrays is weakened, high spatial correlation is maintained only among scheduling users corresponding to the same antenna subarray, and linear precoding and non-linear precoding are performed. Cascade precoding in a combined manner improves the gain of multi-user multiplexing and increases cell throughput.

FIG. 5 is a schematic diagram of signaling exchange of the multi-antenna transmission method according to the embodiment of the present application. In the figure, the base station, the scheduling target users UE1, ..., UEK are included. As shown in FIG. 5, this method includes the following steps.

At step 501, the base station divides the antenna array into at least two antenna sub-arrays.

In step 502, each UE transmits a first uplink signal to the base station. For example, UE1, ..., UEK each transmit an uplink signal P-SRS to the base station.

In step 503, the base station estimates the transmit side correlation matrix for each antenna subarray based on the first uplink signal received and transmitted from the UE, and the transmit side correlation for each antenna subarray. An eigenvector is calculated from the matrix, and beamforming is performed on the downlink reference signal based on the eigenvector to obtain a BRS.

At step 504, the base station transmits the corresponding BRS to the UE at each antenna subarray.

In step 505, the UE selects an antenna subarray based on the received BRS.

In step 506, the UE feeds back the beam selection information to the base station.

At step 507, the base station schedules the user based on the received beam selection information.

In step 508, the base station triggers transmission of a second uplink signal from each scheduling user to the base station by transmitting downlink control signaling to each scheduling user.

As shown in FIG. 5, it is assumed that UE1 and UEK are scheduling users. In this case, the base station triggers transmission of A-SRS from UE1 and UEK to the base station.

In step 509, each scheduling user transmits a second uplink signal to the base station.

At step 510, the base station cascade precodes the data for each scheduling user based on the received second uplink signal.

In step 511, the base station transmits the precoded data to each scheduling user.

In one embodiment, in addition to transmitting the precoded data, the base station simultaneously sends the signaling configuration information about the demodulation reference signal (DMRS) to the scheduling user for use in the associated demodulation of the UE's data channel. You may send it.

In step 512, each scheduling user detects the received downlink data and obtains the data of its own station from the received downlink data.

FIG. 6 is a schematic diagram of a flow of a method in which the UE side performs multi-antenna transmission in one embodiment of the present application. As shown in FIG. 6, this method includes the following steps.

In step 601, by transmitting the first uplink signal to the base station, the base station estimates the transmitting side correlation parameter for each antenna subarray based on the received first uplink signal, and each antenna. For each sub-array, beamforming is performed on the downlink reference signal based on the transmission side correlation parameter, and the downlink reference signal BRS after beamforming is transmitted to the user terminal by the antenna sub-array. For example, the first uplink signal is P-SRS.

In step 602, the BRS is received from the base station, the beam is selected based on the received BRS, and the beam selection information is generated.

In one embodiment, the UE receives the BRS transmitted by the L antenna subarrays on the base station side, estimates the reference signal reception power (RSRP) of each BRS, and selects one or more BRS from the BRS. Select, for example, select the BRS with the largest RSRP, or select the BRS with the largest RSRP and the BRS with the next largest RSRP. The UE can determine the beam corresponding to these BRSs based on the resources used by the selected BRSs.

Further, the UE may generate different beam selection information depending on whether or not it knows the correspondence between the antenna subarray on the base station side and the beam. Specifically, when the UE cannot know the correspondence, the beam identifier corresponding to the selected BRS is fed back to the base station as beam selection information. If the UE knows the correspondence in advance, the antenna sub-array identifier may be mapped from the beam identifier based on the correspondence, and the antenna sub-array identifier may be fed back to the base station as beam selection information.

In another embodiment, in addition to feeding back the beam selection information to the base station, the UE may also transmit the RSRP of the selected BRS to the base station. As a result, the base station can perform user scheduling with reference to the RSRP of the BRS selected by the UE.

In step 603, the beam selection information is fed back to the base station so that the base station schedules the user based on the received beam selection information.

If the UE is a scheduling user, then steps 604 and 605 are further performed.

In step 604, by receiving the downlink control signaling from the base station and transmitting the second uplink signal to the base station, the base station precodes the data for each scheduling user based on the second uplink signal. And send the precoded data to each scheduling user.

In step 605, precoded data is received from the base station and data detection is performed.

FIG. 7 is a schematic diagram of the configuration of the base station 700 according to the embodiment of the present application. As shown in FIG. 7, the base station 700 includes a division module 710 that divides the antenna array into at least two antenna sub-arrays, and a reception module 720 that receives the first uplink signal transmitted from the user terminal (UE). An estimation module 730 that estimates the transmitting side correlation parameter for each antenna sub-array divided by the division module 710 based on the first uplink signal received by the reception module 720, and an estimation module 730 for each antenna sub-array. Beamforming module 740 that performs beamforming on the downlink reference signal to obtain the downlink reference signal after beamforming based on the transmitting side correlation parameter estimated in the above, and beamforming obtained by the beamforming module 740. It includes a transmission module 750 that transmits a later downlink reference signal to the UE by a corresponding antenna sub-array.

FIG. 8 is a schematic diagram of the configuration of the base station 800 in another embodiment of the present application. In addition to the modules shown in FIG. 7, the base station 800 further includes a scheduling module 760 and a precoding module 770.

In one embodiment, the receiving module 720 further receives the beam selection information fed back from the UE. In response, the scheduling module 760 schedules the user based on the beam selection information received by the receiving module 720.

In one embodiment, the scheduling module 760 determines the antenna subarray selected by the UE based on the beam selection information and groups the UEs based on the scheduling balance principle and the antenna subarray selected by the UE. A scheduling target UE group corresponding to each antenna sub-array is obtained, and a scheduling user for transmitting data by the antenna sub-array corresponding to the scheduling target UE group is determined for each scheduling target UE group.

In one embodiment, the transmit module 750 further triggers transmission of a second uplink signal from each scheduling user to the base station by transmitting downlink control signaling to each scheduling user determined by the scheduling module 760. do. The receiving module 720 further receives a second uplink signal transmitted from each scheduling user.

In response to this, the precoding module 770 precodes the data for each scheduling user determined by the scheduling module 760 based on the second uplink signal received by the receiving module 720. The transmission module 750 further transmits the precoded data obtained by the precoding module 770 to each scheduling user.

In some embodiments, the precoding module 770 further estimates the downlink channel state information for each scheduling user based on the second uplink signal, and from the downlink channel information of all scheduling users, the first The second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix, and the precoding matrix for each scheduling user is calculated. Data for each scheduling user is precoded based on the second precoding matrix.

In some embodiments, the first precoding matrix is a linear precoding matrix, the second precoding matrix is a non-linear precoding matrix, and the precoding module 770 further comprises the linear precoding. Based on the matrix and the non-linear precoding matrix, the data for each scheduling user is precoded twice.

FIG. 9 is a schematic diagram of the configuration of the user terminal 900 according to the embodiment of the present application. As shown in FIG. 9, the user terminal 900 transmits the first uplink signal to the base station whose antenna array is divided into at least two antenna subarrays, so that the base station receives the first uplink signal. Estimates the transmitting side correlation parameter indicating the spatial correlation between different transmitting side radio propagation channels for each antenna subarray based on, and for each antenna subarray, downlink reference based on the transmitting side correlation parameter. A transmission module 910 that performs beam forming on the signal and transmits the downlink reference signal after beam forming to the user terminal by the antenna subarray, and reception that receives the downlink reference signal after beam forming from the base station. It includes a module 920 and.

In one embodiment, the user terminal 900 further comprises a selection module 930 that selects a beam and generates beam selection information based on the beamforming downlink reference signal received by the reception module 920.

In response, the transmission module 910 further feeds back the beam selection information determined by the selection module 930 to the base station so that the base station schedules the user based on the beam selection information. The base station determines the antenna sub-array selected by the user terminal based on the beam selection information, and groups the user terminals based on the scheduling balance principle and the antenna sub-array selected by the user terminal. Then, the scheduling target user terminal group corresponding to each antenna subarray is obtained.

In some embodiments, the transmission module 910 further transmits a second uplink signal to the base station in response to downlink control signaling transmitted from the base station, wherein the base station. The first precoding matrix and the second precoding matrix are obtained from the second uplink signal, and the data of the user terminal is obtained based on the first precoding matrix and the second precoding matrix. Precoding twice to obtain the precoded data, the receiving module 920 further receives the precoded data from the base station.

As a person skilled in the art should understand, the functions of the processing modules in the user terminal and the base station of the embodiment of the present application can be understood by referring to the related description of the embodiment regarding the above-mentioned method, and the implementation of the present application can be understood. Each processing module in the user terminal and the base station of the example can be realized by executing the software for realizing the embodiment of the present application on the user terminal and the base station.

In some of the embodiments provided herein, it should be understood that the disclosed devices and methods may be implemented in other ways. The examples relating to the equipment described above are only exemplary. For example, the division of the module is merely a division of logical functions, and may be another division method when it is actually realized. For example, multiple modules or assemblies may be combined, incorporated into other systems, some configurations may be ignored, or some configurations may not be executed. Also, the coupling, direct coupling, or communication connection of each component shown or described may be via some interface, and the indirect coupling or communication connection of equipment or modules may be electrical. , Mechanical, or other form.

As will be appreciated by those skilled in the art, all or part of the steps to implement an embodiment of the above method may be performed by programmatically instructing the relevant hardware. The above-mentioned program may be stored in a computer-readable storage medium. When running the program, steps are performed that include examples of the above methods. The storage medium described above includes various media capable of storing a program code, such as a mobile storage device, a read-only memory (ROM: Read-Only Memory), a random access memory (RAM: Random Access Memory), a magnetic disk, and an optical disk. ..

The above is merely a preferred embodiment of the present application and does not limit the scope of protection of the present application. All modifications, equal replacements, improvements, etc. made within the principles of the present application should be within the scope of protection of the present application.

210 Antenna Array 211, 212, 213, 214 Antenna Sub Array 221, 222, 223, 224 Antenna Sub Array 231, 232, 233, 234 Antenna Sub Array 300 Antenna Array 310, 320 Antenna Sub Array 700 Base Station 710 Split Module 720 Receive Module 730 Estimate Module 740 Beam forming module 750 Transmission module 760 Scheduling module 770 Precoding module 800 Base station 900 User terminal 910 Transmission module 920 Reception module 930 Selection module

Claims (11)

It is a multi-antenna transmission method and is applied to base stations.
Divide the antenna array into at least two antenna sub-arrays
Based on the received first uplink signal transmitted from the user terminal (UE), a transmitter correlation parameter indicating the spatial correlation between different transmitter radio propagation channels for each antenna subarray is estimated. ,
For each antenna sub-array, beamforming is performed on the downlink reference signal based on the transmitting side correlation parameter, and the downlink reference signal after beamforming is transmitted to the UE by the antenna sub-array.
Look at including it,
The method receives the beam selection information fed back from the UE, schedules the user based on the received beam selection information, and
By transmitting downlink control signaling to each scheduling user, each scheduling user triggers transmission of a second uplink signal to the base station.
Further including precoding the data for each scheduling user based on the second uplink signal and transmitting the precoded data to each scheduling user.
Here, precoding the data for each scheduling user based on the second uplink signal is possible.
Based on the second uplink signal, the downlink channel state information for each scheduling user is estimated, and the downlink channel state information is estimated.
The first precoding matrix is calculated from the downlink channel state information of all scheduling users.
A second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix.
Includes precoding data for each scheduling user based on the first precoding matrix and the second precoding matrix.
Here, the first precoding matrix is a linear precoding matrix used between the antenna subarrays, and the second precoding matrix is a non-linear precoding matrix used within the antenna subarrays.
A method characterized by that. Performing beamforming on the downlink reference signal based on the transmitter correlation parameter
The method according to claim 1, wherein a unique parameter is calculated from the transmission side correlation parameter, and beamforming is performed on the downlink reference signal based on the unique parameter. The sender-side correlation parameter is a sender-side correlation matrix, and the eigenvalue is a eigenvector corresponding to the maximum eigenvalue of the sender-side correlation matrix and / or a next-order eigenvalue of the sender-side correlation matrix. The method according to claim 2, characterized in that it is a corresponding eigenvector. Scheduling the user based on the received beam selection information
Based on the beam selection information, the antenna subarray selected by the UE is determined.
The UEs are grouped based on the scheduling balance principle and the antenna subarrays selected by the UEs to obtain the scheduling target UE groups corresponding to each antenna subarray.
For each scheduling target UE group, a scheduling user for transmitting data by the antenna subarray corresponding to the scheduling target UE group is determined.
The method according to claim 1 , wherein the method includes the above. The first based on the precoding matrix and the second pre-coding matrix, the data for each scheduling user to precoding,
Includes precoding the data for each scheduling user twice based on the linear precoding matrix and the non-linear precoding matrix.
The method according to claim 1. Sending the precoded data to each scheduling user
Set different transmission time zones, specify one transmission time zone for each antenna subarray,
The pre-coded data is transmitted in a specified transmission time zone by the antenna sub-array corresponding to the scheduling user.
The method according to claim 1 , wherein the method includes the above. It ’s a base station,
With the processor
With a memory connected to the processor
A plurality of command modules including a division module, a reception module, an estimation module, a beam forming module, and a transmission module are stored in the memory, and when the command module is executed by the processor, the following The process is executed and
The split module splits the antenna array into at least two antenna subarrays.
The receiving module receives the first uplink signal transmitted from the user terminal (UE), and receives the first uplink signal.
The estimation module estimates a transmitting side correlation parameter indicating the spatial correlation between different transmitting side radio propagation channels for each antenna subarray based on the received first uplink signal.
The beamforming module performs beamforming on the downlink reference signal based on the transmission side correlation parameter for each antenna subarray to obtain a downlink reference signal after beamforming.
The transmission module transmits the downlink reference signal after beamforming to the UE by a corresponding antenna subarray .
Here, the receiving module further receives the beam selection information fed back from the UE, and receives the beam selection information.
The base station
It also has a scheduling module that schedules users based on the received beam selection information.
The transmission module further triggers transmission of a second uplink signal from each scheduling user to the base station by transmitting downlink control signaling to each scheduling user.
The receiving module further receives a second uplink signal transmitted from each scheduling user.
The base station
Further equipped with a precoding module that precodes the data for each scheduling user based on the received second uplink signal.
The transmit module further transmits precoded data to each scheduling user.
Here, the precoding module estimates the downlink channel state information for each scheduling user based on the second uplink signal, and obtains the first precoding matrix from the downlink channel state information of all scheduling users. The second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix, and the first precoding matrix and the second precoding matrix are calculated. Precode the data for each scheduling user based on the coding matrix and
Here, the first precoding matrix is a linear precoding matrix used between the antenna subarrays, and the second precoding matrix is a non-linear precoding matrix used within the antenna subarrays.
A base station characterized by that. The scheduling module determines the antenna sub-array selected by the UE based on the beam selection information, and groups the UEs based on the scheduling balance principle and the antenna sub-array selected by the UE. 7. A aspect of claim 7, wherein a scheduling target UE group corresponding to each of the antenna sub-arrays is obtained, and a scheduling user to transmit data by the antenna sub-array corresponding to the scheduling target UE group is determined for each scheduling target UE group. The base station described in. The precoding module is pre-SL based on the linear precoding matrix with the non-linear pre-coding matrix, twice precoding data for each scheduling user,
The method according to claim 7 , wherein the method is characterized by the above. It is a user terminal
With the processor
With a memory connected to the processor
A plurality of command modules including a transmission module and a reception module are stored in the memory, and when the command module is executed by the processor, the following processing is executed.
The transmitting module transmits a first uplink signal to a base station in which the antenna array is divided into at least two antenna subarrays, so that the base station receives each antenna based on the received first uplink signal. A transmitter correlation parameter indicating the spatial correlation between different transmitter radio propagation channels for each subarray is estimated, and a beam is applied to the downlink reference signal for each antenna subarray based on the transmitter correlation parameter. Forming is performed, and the downlink reference signal after beamforming is transmitted to the user terminal by the antenna subarray.
The receiving module, from the base station, receives downlink reference signal after beam forming,
Here, the user terminal further includes a selection module that selects a beam based on the received downlink reference signal after beamforming and generates beam selection information.
The transmission module further feeds back the beam selection information to the base station so that the base station schedules the user based on the beam selection information.
In response to the downlink control signaling transmitted from the base station, a second uplink signal is transmitted to the base station, where the base station is based on the second uplink signal for each scheduling user. The downlink channel state information is estimated, the first precoding matrix is calculated from the downlink channel status information of all scheduling users, and each scheduling is performed from the downlink channel status information for each scheduling user and the first precoding matrix. A second precoding matrix for each user was calculated, and based on the first precoding matrix and the second precoding matrix, the data of the user terminal was precoded twice and precoded. Get the data
The receiving module further receives the precoded data from the base station and receives the precoded data.
Here, the first precoding matrix is a linear precoding matrix used between the antenna subarrays, and the second precoding matrix is a non-linear precoding matrix used within the antenna subarrays.
A user terminal characterized by that. Non-volatile computer readable storage medium
A machine-readable command is stored in the storage medium, and the machine-readable command is
Divide the antenna array into at least two antenna sub-arrays
Based on the received first uplink signal transmitted from the user terminal (UE), a transmitter correlation parameter indicating the spatial correlation between different transmitter radio propagation channels for each antenna subarray is estimated. ,
For each antenna sub-array, beamforming is performed on the downlink reference signal based on the transmitting side correlation parameter, and the downlink reference signal after beamforming is transmitted to the UE by the antenna sub-array.
The beam selection information fed back from the UE is received, the user is scheduled based on the received beam selection information, and the user is scheduled.
By transmitting downlink control signaling to each scheduling user, each scheduling user triggers transmission of a second uplink signal to the base station.
It can be executed by the processor to complete precoding the data for each scheduling user based on the second uplink signal and transmitting the precoded data to each scheduling user.
Here, precoding the data for each scheduling user based on the second uplink signal is possible.
Based on the second uplink signal, the downlink channel state information for each scheduling user is estimated, and the downlink channel state information is estimated.
The first precoding matrix is calculated from the downlink channel state information of all scheduling users.
A second precoding matrix for each scheduling user is calculated from the downlink channel state information for each scheduling user and the first precoding matrix.
Includes precoding data for each scheduling user based on the first precoding matrix and the second precoding matrix.
Here, the first precoding matrix is a linear pre-coding matrix to be used between the antenna sub-arrays, said second precoding matrix is a non-linear pre-coding matrix to be used in the antenna sub-arrays, and this A feature non-volatile computer readable storage medium.

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