WO2017124968A1

WO2017124968A1 - Mixed beamforming method, base station, and user terminal

Info

Publication number: WO2017124968A1
Application number: PCT/CN2017/071030
Authority: WO
Inventors: 侯晓林; 蒋惠玲; 加山英俊
Original assignee: 株式会社Ntt都科摩
Priority date: 2016-01-21
Filing date: 2017-01-13
Publication date: 2017-07-27
Also published as: CN108476054A; CN108476054B; CN106998223A; JP2019508934A

Abstract

Disclosed in the present invention are a mixed beamforming method, a base station, and a user terminal. When applied to the base station, the method comprises: receiving simulation beam identifiers fed back by a user terminal; determining to-be-formed simulation beams and a scheduled user corresponding to each to-be-formed simulation beam according to the simulation beam identifiers; generating a simulation beamforming weight for each to-be-formed simulation beam, and calculating a digital precoding weight for each scheduled user according to channel state information of each scheduled user and the simulation beamforming weight; and performing mixed beamforming on data of each scheduled user according to the simulation beamforming weight and the digital precoding weight, and sending, to each scheduled user, the data on which mixed beamforming has been performed. By means of the method, the base station and the user terminal in the present invention, a mixed beamforming transmission solution taking both performance and complexity into consideration can be provided.

Description

Hybrid beamforming method, base station and user terminal

Technical field

The present invention relates to the field of communications, and in particular, to a hybrid beamforming method, a base station, and a user terminal.

Background of the invention

With the development of antenna technology, large-scale antenna array systems (AAS) are gradually being applied to base stations. Such large-scale AAS usually includes hundreds of antenna elements (such as 128, 256 or more), and these elements can be arranged in a panel type as an area array antenna. By installing AAS on the base station side and using Multiple Input Multiple Output (MIMO) transmission, wireless communication can be provided to more users at the same time.

In the implementation of massive MIMO technology, if one transceiver unit is installed for each antenna element, the complexity, power consumption and cost of implementation will be increased. The hybrid beamforming technology enables multiple antenna elements to share one transceiver unit, which reduces the cost of implementation and becomes a research hotspot in the field of wireless communication.

In the current AAS system, the analog beamforming weights usually use fixed or quasi-static values, and the analog beam transmission cannot be dynamically adjusted according to the specific distribution of multiple users, so that the spatial freedom brought by large-scale AAS cannot be fully utilized. . Therefore, in the scenario where large-scale AAS is applied, it is necessary to design a hybrid beamforming scheme that combines performance and complexity.

Summary of the invention

The invention provides a hybrid beamforming method, a base station and a user terminal, which can improve the flexibility of user scheduling, and at the same time take into account computational complexity and system performance.

Specifically, the technical solution of the embodiment of the present invention is implemented as follows:

A hybrid beamforming method is applied to a base station, and the method includes:

Receiving an analog beam identifier fed back by the user terminal;

Determining an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam based on the analog beam identification;

Generating an analog beamforming weight for each analog beam to be shaped, and calculating a digital precoding weight for each scheduling user according to channel state information of each scheduling user and the analog beam shaping weight; and

And performing hybrid beamforming on the data of each scheduled user according to the analog beamforming weight and the digital precoding weight, and transmitting the mixed beamformed data to each scheduling user.

A user terminal comprising:

a sending module, configured to send an analog beam identifier to the base station, so that the base station determines, according to the simulated beam identifier, an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam, for each to-be-formed simulation Beams, generating analog beamforming weights, and calculating digital precoding weights for each scheduling user according to channel state information of each scheduling user and the analog beamforming weights, according to the analog beamforming weights The digital precoding weights perform hybrid beamforming on data of each scheduled user;

And a receiving module, configured to receive the data after the hybrid beamforming sent by the base station.

It can be seen from the foregoing technical solutions that the hybrid beamforming method, the base station, and the user terminal provided by the embodiments of the present invention can simultaneously generate one or more analog beams for scheduling and shaping, taking into account the real distribution of the users to be scheduled. The flexibility of user scheduling can make full use of time-frequency resources, providing a hybrid beamforming transmission scheme that combines performance and complexity for scenarios using AAS.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are only a few examples of the technical solutions of the present invention, and the present invention is not limited to the features shown in the drawings. In the following figures, like reference numerals indicate similar elements:

1 is a schematic flow chart of a hybrid beamforming method according to an embodiment of the present invention;

2a is a schematic diagram showing division of an antenna sub-array according to an embodiment of the present invention;

2b is a schematic diagram showing division of an antenna sub-array according to another embodiment of the present invention;

2c is a schematic diagram showing division of an antenna sub-array according to still another embodiment of the present invention;

2d is a schematic diagram showing division of an antenna sub-array according to an embodiment of the present invention;

3 is a schematic diagram of a composition of a hybrid beamforming transmitting end according to an embodiment of the present invention;

4 is a schematic flow chart of a hybrid beamforming method according to another embodiment of the present invention;

FIG. 5 is a schematic diagram of BRS resource allocation according to an embodiment of the present invention; FIG.

6 is a schematic diagram of signaling interaction of a hybrid beamforming method according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a base station according to an embodiment of the present invention; FIG.

FIG. 8 is a schematic structural diagram of a base station according to another embodiment of the present invention; FIG.

FIG. 9 is a schematic structural diagram of a user terminal according to an embodiment of the present invention; FIG.

FIG. 10 is a schematic structural diagram of a user terminal according to another embodiment of the present invention.

Mode for carrying out the invention

For the sake of brevity and clarity of the description, the aspects of the present invention are set forth below by describing several representative embodiments. However, not all embodiments are shown herein. A large number of the details in the embodiments are only used to help understand the solution of the present invention, and the technical solutions of the present invention may not be limited to these details. In order to avoid unnecessarily obscuring aspects of the present invention, some embodiments are not described in detail, but only the framework is given. Hereinafter, "including" means "including but not limited to", and "according to" means "at least according to ..., but not limited to only based on". The word "comprising" in the specification and claims refers to at least some of the In addition to the features mentioned later, other features may also be present.

Embodiments of the present invention provide a hybrid beamforming method, which is applied to a base station. As shown in Figure 1, the following steps are included.

Step 101: Receive an analog beam identifier fed back by a user terminal (UE).

Step 102: Determine an analog beam to be shaped and a scheduled user corresponding to each analog beam to be shaped based on the simulated beam identification.

Step 103: Generate an analog beamforming weight for each analog beam to be shaped, and calculate a digital precoding weight for each scheduling user according to channel state information and analog beam shaping weight of each scheduling user.

Step 104: Perform hybrid beamforming on the data of each scheduled user according to the simulated beamforming weight and the digital precoding weight, and send the mixed beamformed data to each scheduling user.

The above various steps will be specifically described below.

In step 101, the base station divides the antenna array into at least one antenna sub-array, and determines a spare analog beam corresponding to each antenna sub-array. A beam-formed downlink reference signal (BRS) is generated for each of the alternate analog beams, and the beam-formed downlink reference signal is sent to the UE, so that the UE determines the feedback according to the beam-formed downlink reference signal. Analog beam identification.

The method for dividing the antenna sub-array may be various, including performing uniform division or non-uniform division according to the structure of the antenna array. Alternatively, the antenna elements having the same polarization direction are divided into one antenna sub-array according to the polarization direction of the antenna elements. Alternatively, the antenna array is uniformly divided or non-uniformly divided in combination with the polarization direction of the antenna element.

It should be noted that the number of antenna elements included in each antenna sub-array may be the same or different. In addition, the antenna elements between different antenna sub-arrays may also overlap, ie comprise one or more common antenna elements. Wherein, the shape of the antenna sub-array and the included antenna The number of array elements will affect the shape and coverage of the alternate analog beam it forms.

Taking a two-dimensional antenna array as an example, FIG. 2a is a schematic diagram of dividing an antenna sub-array according to an embodiment of the present invention, and dividing the antenna array into blocks. The antenna array 210 is evenly divided into four

antenna sub-arrays

211, 212, 213, and 214. Each antenna sub-array is a regular square antenna array, and each includes four antenna array elements.

2b is a schematic diagram showing the division of an antenna sub-array according to another embodiment of the present invention. The antenna array 210 is evenly divided into four

antenna sub-arrays

221, 222, 223, and 224 in the lateral direction, and each antenna sub-array is a regular horizontal strip antenna array, each of which includes four antenna array elements.

2c is a schematic diagram showing the division of an antenna sub-array according to still another embodiment of the present invention. Wherein, the antenna array 210 is evenly divided into four

antenna sub-arrays

231, 232, 233 and 234 in the longitudinal direction, and each antenna sub-array is a regular longitudinal strip antenna array, each comprising four antenna elements.

2d is a schematic diagram showing the division of an antenna sub-array according to an embodiment of the present invention. The antenna array element in the antenna array 220 includes two polarization modes, namely vertical polarization and horizontal polarization. The antenna array 220 is divided according to the two polarization modes and in the longitudinal direction: the vertically polarized

antenna sub-arrays

221, 222, 223 and 224, and the horizontally polarized

antenna sub-arrays

225, 226, 227 and 228, Each contains 4 antenna elements.

The method for dividing the antenna sub-array is only an example. In the specific application, other types of division methods may also be used, which are not specifically limited in this application.

In step 102, the base station performs user scheduling, and determines an analog beam to be shaped and a scheduled user corresponding to each analog beam to be shaped based on the simulated beam identification.

Specifically, one or more analog beams to be shaped corresponding to the received analog beam identifier are determined from all the alternate analog beams, and the UEs are grouped according to the to-be-shaped analog beams, and obtained and each And a set of to-be-scheduled UEs corresponding to the simulated analog beams, and then, for each group of to-be-scheduled UEs, determine a scheduling user that uses the to-be-formed analog beam transmission data corresponding to the group of to-be-scheduled UEs.

FIG. 3 is a schematic diagram of the composition of a hybrid beamforming transmitting end according to an embodiment of the present invention. The antenna array is divided into L antenna sub-arrays 341...34L, and each antenna sub-array corresponds to an analog beamformer 331...33L. The analog beamformer is coupled to the L transceiver units 320, and the transceiver unit 320 is coupled to the digital precoder 310. The transceiver unit is configured to perform operations such as digital-to-analog/analog-to-digital conversion, Fourier transform/inverse Fourier transform (FFT/IFFT), and the digital precoder is used to generate digital precoding weights.

For each antenna sub-array, multiple alternate analog beams can be generated by loading different weights by corresponding analog beamformers. Considering a codebook based beamforming scheme, if each code sub-array contains V codebook vectors in a codebook, each codebook vector is beam-shaped as a weight for each antenna sub-array. V spare analog beams can be generated. If the total number of spare analog beams that the entire antenna array can provide is C, then C=L*V. Where L is the total number of antenna sub-arrays, and can also characterize the number of analog beams that the antenna array can emit at the same time.

Based on the simulated beam identification of the user feedback, the base station can determine B to be shaped analog beams from the C spare analog beams, where B≤C, B≥L or B<L. The base station groups the UEs for the determined B to be shaped analog beams, and obtains the B groups of the to-be-scheduled UEs, and further determines the group B scheduling users from the group B to be scheduled UEs, where each group of scheduling users includes one or more Schedule users.

Referring to Figure 3, each antenna sub-array can be coupled to one or more transceiver units via an analog beamformer. From the perspective of the UE, one or more transceiver units can be mapped to one antenna port (AP), and therefore, the total amount of APs is less than or equal to the total amount L of the transceiver units. When the transceiver unit and the AP adopt a one-to-one mapping, the number of the two is the same.

According to the embodiment of the present application, the number of transceiver units corresponding to each analog beam to be shaped may be determined according to the determined number of analog beams to be shaped, thereby dynamically adjusting the number of transceiver units corresponding to each analog beam.

When the number B of the analog beams to be shaped is smaller than the total number L of the antenna sub-arrays (that is, the number of analog beams that can be simultaneously transmitted by the antenna array), the number of transceiver units corresponding to each of the analog beams to be shaped may be adjusted.

For example, each of the analog beams to be shaped may be corresponding to one transceiver unit by default. When the number B of the analog beams to be shaped is smaller than the total number L of the antenna sub-arrays, it may be determined that each of the analog beams to be shaped corresponds to at least one transceiver unit.

In some examples, each of the analog beams to be shaped may correspond to the same number of transceiver units.

In other examples, each of the analog beams to be shaped may correspond to a different number of transceiver units. The number of transceiver units corresponding to each analog beam to be shaped may be determined according to B, L and preset rules. In some examples, the number of transceiver units corresponding to each of the analog beams to be shaped may be related to the number of scheduled users corresponding to each of the analog beams to be shaped. For example, more analog transmit beams to be shaped by the user may correspond to more transceiver units, thereby improving the reception quality of as many users as possible. The specific rules can be determined according to the actual situation.

In some examples, when it is determined that one analog beam to be shaped corresponds to multiple transceiver units, multiple transceiver units having a larger physical distance can be selected for the analog beam to be shaped, so that the performance of digital precoding can be better.

In some examples, at least one transceiver unit can be turned off. For example, the transceiver unit other than the transceiver unit corresponding to each of the analog beams to be shaped may be turned off. For example, when it is determined that each of the to-be-shaped analog beams corresponds to m transceiver units, if L>m*B, (L-m*B) transceiver units are turned off.

For example, at least one transceiver unit can be turned off, and the number of transceiver units corresponding to each analog beam to be shaped is kept constant. For example, when the number of scheduling users corresponding to each of the to-be-formed analog beams is less than a preset threshold, each of the to-be-shaped analog beams may be determined to correspond to a default number of transceiver units, and the remaining transceiver units are turned off.

For example, the transceiver unit that is not previously connected to the antenna sub-array corresponding to the analog beam to be shaped is turned off. If the B analog beams to be shaped correspond to the antenna sub-arrays

(B<L), then the alternate analog beam that does not need to be shaped corresponds to the antenna sub-array B+1, . . . , L, then the transceiver unit connected to the antenna sub-array B+1, . . . , L is closed, so that it is not closed. The number of transceiver units is equal to the number of analog beams to be shaped.

In other examples, the number of transceiver units corresponding to at least one analog beam to be shaped may be increased such that each transceiver unit corresponds to one of the at least one analog beam to be shaped. For example, more transceiver units can be used to transmit more to-be-formed analog beams for scheduling users.

For example, the number of transceiver units corresponding to at least one analog beam to be shaped may be increased, that is, the transceiver units that are not previously connected to the antenna sub-arrays corresponding to the analog beams to be shaped are reassigned to the to-be-formed analog beams. It can be seen that the number of transceiver units corresponding to each analog beam to be shaped is configurable, and can be adjusted according to the determined number of analog beams to be shaped. Here, the "allocation" of the transceiver unit to the analog beam to be shaped means that the antenna element connected to the transceiver unit adopts a beam shaping weight corresponding to the to-be-shaped analog beam, that is, the transceiver unit transmits the to-be-assigned Shaped analog beam.

In step 103, for the B to be shaped analog beams, analog beamforming weights W ₁ , . . . , W _B are respectively generated, for example, based on a preset codebook to generate analog beamforming weights, such as discrete Fourier transform. (DFT) codebook, the size of the codebook is greater than B. The group B scheduling user is also determined by step 102, and the user is scheduled for the group b (b=1, . . . , B), according to the generated analog beam shaping weight W _b and the channel state of each scheduling user in the group of scheduling users. The information is generated for the digital precoding weight _Pk , where k = 1, ..., K, K is the total number of all scheduled users.

The obtaining channel state information of the scheduling user includes: each scheduling user sends an uplink reference signal, such as an aperiodic channel sounding reference signal (A-SRS), to the base station. The base station then performs channel estimation according to the received uplink reference signal, and according to the channel reciprocity (channel The reciprocity principle estimates the downlink channel state information of the entire antenna array.

When performing digital precoding, the digital precoding weight may be generated based on the codebook method, or may be based on the non-codebook method, for example, generating digital precoding weights based on channel state information acquired according to the channel reciprocity principle.

In step 104, hybrid beamforming is performed on the data of each of the scheduled users based on the simulated beamforming weights and the digital precoding weights. For example, for the kth scheduled user, the data of the user is first precoded on the digital domain using the digital precoding weight _Pk to obtain precoded data. After the step 102 has determined that the scheduled user with the b-th to be shaped simulation beam corresponds, analog beamforming weights W is _b data after the pre-coded analog beamforming, whereby a mixed beamforming Data, and then the mixed beamformed data is sent to the scheduled user in the antenna sub-array corresponding to the bth to-be-formed analog beam.

In step 104, when different antenna sub-arrays include a common antenna array element, performing analog beamforming according to the above-mentioned analog beamforming weights is equivalent to superimposing the coefficients in the analog beamforming weights, and then according to the superimposed The coefficients weight the simulated beamforming of the common antenna element.

In the embodiment shown in FIG. 1 , the analog beam identifier fed back by the UE is received, and the analog beam to be shaped and the scheduled user corresponding to each analog beam to be shaped are determined based on the simulated beam identifier, for each shape to be shaped. Simulating the beam, generating the simulated beamforming weights, and calculating the digital precoding weights for each scheduling user according to the channel state information and the simulated beamforming weight of each scheduling user, according to the simulated beamforming weights and the digital precoding weights Hybrid beamforming is performed on the data of each scheduled user. Considering the real distribution of the users to be scheduled, one or more analog beams can be simultaneously generated for scheduling and shaping, which improves the flexibility of user scheduling and can be fully utilized. The frequency resource provides a hybrid beamforming transmission scheme that combines performance and complexity for scenarios using AAS.

For example, in a typical scenario, a large-scale AAS is installed on the base station side, including high-rise buildings within its coverage, considering that the number of users in each floor is variable, such as the number of users in each floor in a school building. If the time is changed, the analog beam identifier fed back by the UE can effectively reflect the real user distribution by using the method described in the foregoing embodiment. The base station determines multiple analog beams to be shaped, and generates analog beamforming weights respectively. Different beams are transmitted in multiple directions in the spatial domain, for example, covering users in different floors, thereby effectively improving coverage and increasing cell throughput.

In addition, when the number of analog beams to be shaped is smaller than the total number of antenna sub-arrays, turning off the transceiver unit that is not connected to the antenna sub-array corresponding to the analog beam to be shaped can save power loss at the transmitting end. Alternatively, the number of transceiver units is adaptively adjusted according to the determined number of analog beams to be shaped, so that the number of transceiver units corresponding to each analog beam to be shaped is variable, thereby fully utilizing the transceiver unit and improving each simulation. The number of users that the beam can serve simultaneously.

FIG. 4 is a schematic flowchart diagram of a hybrid beamforming method according to another embodiment of the present invention, where the method is applied to a base station. As shown in Figure 4, the following steps are included:

Step 400: Send a first BRS to the UE, so that the UE determines an analog beam identifier to be fed back according to the first BRS.

In this step, the base station performs beamforming on the downlink reference signal, for example, using the above codebook-based method to generate an analog beamforming weight, and performing analog beamforming on the downlink reference signal according to the simulated beamforming weight, and shaping the analog beam. The subsequent downlink reference signal is used as the first BRS. Sending a plurality of first BRSs to the UE by using specific time-frequency resources. The plurality of first BRSs may be multiplexed on time-frequency resources using time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM), or cyclic shift (CS). The identifiers of all the alternate analog beams are preset on the UE side. The UE may estimate a reference signal received power (RSRP) of each first BRS according to the received first BRS, and select one or more first BRSs from the root. According to the resources occupied by these first BRSs, the analog beam identification to be fed back can be determined.

FIG. 5 is a schematic diagram of BRS resource allocation in an embodiment of the present invention. As shown in FIG. 5, 510, 520, 530, ..., and 5X0 are respectively a resource block (RB). According to the LTE system, one RB is composed of 14 orthogonal frequency division multiplexing (OFDM) symbols and frequencies in the time domain. The resources of 12 subcarriers in the domain are combined, and a resource composed of one OFDM symbol in the time domain and one subcarrier in the frequency domain is called a resource particle (RE).

The plurality of first BRSs may be transmitted using consecutive or equally spaced frequency domain resources. FIG. 5 shows an example of occupying consecutive frequency domain resources, as shown by the trellis pattern in RB 510, occupies multiple OFDM symbols in 511, 512... and 51X for transmission. For each OFDM symbol, all resources in the frequency domain are occupied, that is, the first BRS is transmitted on consecutive frequency domain resources. A plurality of first BRSs may be multiplexed in a CS manner within each OFDM symbol. This type of BRS can also be referred to as a block type BRS.

In a specific application, the first BRS may occupy consecutive OFDM symbols in the time domain, and the number of occupied OFDM symbols depends on the resource mapping manner of the first BRS and the number of transceiver units (that is, the simulation that the antenna array can simultaneously issue) The number of beams) and the number of alternative analog beams. The basic principle is that the transmission of all candidate analog beams can be completed for a given number of OFDM symbol time ranges for the UE to perform analog beam measurements and selection.

Step 401: Receive an analog beam identifier fed back by the UE.

Step 402: Determine an analog beam to be shaped and a scheduled user corresponding to each analog beam to be shaped based on the simulated beam identification.

Step 403: Generate an analog beamforming weight for each analog beam to be shaped, and calculate a digital precoding weight for each scheduling user according to channel state information and analog beam shaping weight of each scheduling user.

The above-mentioned steps 401 to 403 respectively correspond to the steps 101 to 103 in the embodiment of FIG. 1 . Please refer to the above description, and details are not described herein again.

Step 404: Send beam mode information to each UE, so that each UE determines whether to receive the mixed beamformed data according to the beam mode information.

In this step, the base station sends downlink control signaling to each scheduling user, and informs the UE of the beam mode information by using the downlink control signaling. For example, the beam pattern information is characterized by adding a beam pattern indicator to the downlink control signaling. The beam pattern information carries an identifier of the analog beam to be shaped. In addition, the beam mode information may also carry the number of APs corresponding to each analog beam to be shaped.

In a specific application, in order to facilitate the assistance of the UE to determine whether to perform subsequent data reception, the beam mode information may be transmitted at the beginning of each transmission time interval (TTI).

After receiving the beam mode information, the UE reads the analog beam identifier to be shaped and compares it with the analog beam identifier previously fed back to the base station. If the analog beam identifier to be shaped is included in the analog beam identifier that is previously fed back to the base station, the UE continues to detect other control information included in the downlink control signaling, for example, indicating which subband the data of the UE is located, and which one to use. The scheduling information of the coding adjustment mode (MCS) or the like may receive the mixed beamformed data subsequently transmitted by the base station according to the scheduling information. If the analog beam identifier to be shaped is not included in the analog beam identifier, the UE may choose not to detect other information in the downlink control signaling to save power, and then no longer receive data sent by the base station, or the UE. It is also possible to continue to detect other control information included in the downlink control signaling to reconfirm whether the data sent to itself is included, and if confirmed, continue to receive the data after the hybrid beamforming subsequently transmitted by the base station.

Step 405: Perform hybrid beamforming on the data of each scheduled user according to the simulated beamforming weight and the digital precoding weight, and send the mixed beamformed data to each scheduling user, and in the discontinuous time-frequency resource. The second BRS is sent to the scheduling user.

In this step, the base station performs beamforming on the downlink reference signal to generate a second BRS. For example, performing downlink reference signals according to the above-mentioned analog beamforming weights and digital precoding weights The hybrid beam is shaped, and the downlink reference signal after the hybrid beamforming is used as the second BRS. In a specific application, the downlink reference signal used to generate the second BRS may be a channel state indication reference signal (CSI-RS).

When the mixed beamformed data is sent to the scheduling user, the second BRS is simultaneously sent to the scheduling user, and the second BRS carries the digital precoding weight of the scheduling user. In an embodiment, the second BRS may also be used as a Demodulation Reference Signal (DMRS) for scheduling associated demodulation of the user's data channel.

The plurality of second BRSs may be multiplexed on discontinuous time-frequency resources by means of TDM, FDM, CDM or CS.

Referring to FIG. 5, different from the manner of sending the first BRS in step 100, the time-frequency resources dispersed in the

RBs

520, 530, ..., and 5X0 may be used when transmitting the second BRS, as shown by the trellis pattern, wherein a trellis pattern is used. It is composed of a plurality of discontinuous REs, and the data after the hybrid beamforming is transmitted on the time-frequency resources other than the lattice pattern, that is, the multiplexing method using TDM and FDM. This type of second BRS can be referred to as a scattered BRS.

It should be noted that the first BRS is used by the UE to feed back the analog beam identifier to the base station, so that the base station schedules the user according to the received analog beam identifier; and the second BRS is sent to the scheduling user together with the data after the hybrid beamforming. The user is scheduled to demodulate data, estimate channel information (such as channel quality indicator CQI, precoding matrix indication PMI, rank indicator RI), and track analog beams. Therefore, the transmission period of the first BRS can be longer than the second BRS. Usually, the transmission period is determined according to the speed at which the user moves and the speed at which the environment changes.

After receiving the second BRS, the scheduling user performs channel estimation to obtain a beamformed CQI, and feeds the beamformed CQI to the base station. The CQI after the beamforming is a CQI after the hybrid beam is shaped.

Step 406: Determine, according to the received channel quality of the beamforming, whether the scheduling user is triggered to feed back the analog beam identifier to the base station.

In this step, the base station can track the quality of the analog beam to be shaped according to the channel quality after the received beamforming. Specifically, the base station may set a CQI threshold. When the received CQI of the beamforming is lower than the threshold, the analog beam directed to the scheduling user is inaccurate, and it is determined that the scheduling user needs to be triggered to re-feed the analog beam. Identifies, otherwise the scheduled user cannot continue to serve.

In addition, the base station can also adjust the scheduling result according to the received channel quality after the beamforming, that is, perform link adaptation. For example, the base station can adjust various parameters for data transmission, such as RI, PMI, MCS, and power.

In addition, in the foregoing step 405, when the data of the hybrid beamforming is sent to the scheduling user, considering that one antenna sub-array may correspond to multiple analog beams to be shaped, the base station may determine the analog beam and the antenna to be shaped. The corresponding relationship of the sub-arrays is then sent to each dispatching user in a multiplexing manner according to the corresponding relationship.

For example, in step 402, the number B of the to-be-formed analog beams determined by the base station is greater than the total number L of the antenna sub-arrays, that is, B>L, then when the mixed beamformed data is transmitted in step 405, the L antenna sub-arrays are passed. Send B group scheduling user data. In this case, the multiplexing mode that the base station can adopt may be time division multiplexing (TDM), frequency division multiplexing (FDM), space division multiplexing (SDM), and any combination thereof. E.g,

(1) If TDM is used, an shaped analog beam can be transmitted on each TTI. This analog beam is for the entire bandwidth, that is, it is effective over the entire bandwidth.

(2) If TDM and FDM are combined, X analog beams can be transmitted on each TTI using X subbands, X>1. Each analog beam is for a sub-band, ie it is valid on the corresponding sub-band.

(3) If TDM is combined with SDM, Y analog beams are transmitted over the entire bandwidth of each TTI, Y>1.

At this time, it is determined that the Y-group scheduling users have good isolation in the airspace, or the sender-side correlation between the Y-group scheduling users is weak. From the perspective of beam propagation, the beam distance between the Y analog beams is large, or the angle between the radiation directions of the Y analog beams is large.

(4) If TDM is combined with FDM and SDM, Y analog beams are transmitted using X subbands on each TTI, Y>X.

Based on the embodiment shown in FIG. 4, the beam mode information is sent to each user terminal, and the beam mode information carries the analog beam identifier to be shaped and the number of APs corresponding to each analog beam to be shaped, so that the UE can learn the base station. The analog beam and the AP number information used for downlink transmission are used to accurately detect the received mixed beam data using the information. In addition, the second BRS is sent to the scheduling user for tracking of the simulated beam quality on the discontinuous time-frequency resources, and the better channel estimation quality can be obtained with less overhead. The base station determines whether to trigger the scheduling user to feed back the analog beam identifier to the base station according to the received channel quality, and adjusts the scheduling result, which can further improve the scheduling accuracy and increase the throughput of the cell.

FIG. 6 is a schematic diagram of signaling interaction of a hybrid beamforming method according to an embodiment of the present invention, including a base station and UEs 1 to UE K to be scheduled. As shown in FIG. 6, the following steps are included.

Step 601: The base station divides the antenna array into at least one antenna sub-array.

Step 602: The base station sends the first BRS to the UE 1...UE K on consecutive frequency domain resources.

In step 603, the UE 1 ... UE K selects an analog beam according to the received first BRS.

Step 604, UE 1 ... UE K feeds back the analog beam identification to the base station.

Step 605: The base station determines, according to the received analog beam identifier, a to-be-formed analog beam and a scheduling user corresponding to each to-be-shaped analog beam, and generates an analog beamforming weight for each to-be-shaped analog beam, and according to each The channel state information and the simulated beamforming weights of the scheduling users are calculated, and the digital precoding weights for each scheduling user are calculated.

Step 606: The base station sends beam mode information to each UE, where the beam mode information carries at least an identifier of the analog beam to be shaped.

As shown in FIG. 6, it is assumed that UE 1 and UE K are scheduling users. Step 607: The base station performs hybrid beamforming on the data of each scheduled user according to the simulated beamforming weight and the digital precoding weight, and sends the mixed beamformed data and the second BRS to each scheduling user.

Step 608: Each scheduled user detects the received downlink data, obtains its own data from it, and estimates the CQI after the hybrid beamforming according to the second BRS.

In step 609, each scheduling user feeds back the hybrid beamformed CQI to the base station.

Step 610: The base station determines, according to the received CQI of the hybrid beamforming, whether to trigger the scheduling user to feed back the analog beam identifier to the base station, and adjust the scheduling result.

FIG. 7 is a schematic structural diagram of a base station 700 according to an embodiment of the present invention. As shown in FIG. 7, the method includes:

The receiving module 710 is configured to receive an analog beam identifier fed back by the user terminal.

The scheduling module 720 is configured to determine, according to the simulated beam identifier received by the receiving module 710, an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam;

The hybrid beamforming module 730 is configured to generate an analog beamforming weight for each to-be-shaped analog beam determined by the scheduling module 720, and perform channel state information and analog beamforming for each scheduling user determined by the scheduling module 720. Weighting, calculating a digital precoding weight for each scheduling user, and performing hybrid beamforming on the data of each scheduling user according to the simulated beamforming weight and the digital precoding weight; and

The sending module 740 is configured to shape the hybrid beam obtained by the hybrid beamforming module 730 The subsequent data is sent to each scheduled user.

FIG. 8 is a schematic structural diagram of a base station 800 according to another embodiment of the present invention. As shown in FIG. 8, on the structure of the base station 700 shown in FIG. 7, the base station 800 further includes: a dividing module 750, a transceiver unit management module 760, and BRS generation module 770.

In an embodiment, the dividing module 750 is configured to divide the antenna array into at least one antenna sub-array, and determine a spare analog beam corresponding to each antenna sub-array;

The scheduling module 720 is configured to: determine, from the alternate analog beams corresponding to the antenna sub-array determined by the dividing module 750, an analog beam to be shaped corresponding to the simulated beam identifier.

In an embodiment, each antenna sub-array is coupled to at least one transceiver unit.

The transceiver unit management module 760 can determine the number of transceiver units corresponding to each analog beam to be shaped according to the determined number of analog beams to be shaped. When the number B of the analog beams to be shaped is smaller than the total number L of the antenna sub-arrays, the number of transceiver units corresponding to the analog beams to be shaped may be adjusted. For example, each of the analog beams to be shaped may be corresponding to one transceiver unit by default. When the number B of the analog beams to be shaped is smaller than the total number L of the antenna sub-arrays, the transceiver unit management module 760 may determine that each of the to-be-formed analog beams corresponds to at least one transceiver unit.

In some examples, the transceiver unit management module 760 can determine that each of the analog beams to be shaped corresponds to the same number of transceiver units.

In other examples, the transceiver unit management module 760 can determine that each of the analog beams to be shaped corresponds to a different number of transceiver units. The number of transceiver units corresponding to each analog beam to be shaped may be determined according to B, L and preset rules. In some examples, the number of transceiver units corresponding to each of the analog beams to be shaped may be related to the number of scheduled users corresponding to each of the analog beams to be shaped. For example, more analog transmit beams to be shaped by the user may correspond to more transceiver units, thereby improving the reception quality of as many users as possible. The specific rules can be determined according to the actual situation.

In some examples, when it is determined that one analog beam to be shaped corresponds to multiple transceiver units, The sending unit management module 760 can select a plurality of transceiver units having a large physical distance for the to-be-shaped analog beam, so that the performance of the digital precoding can be better.

In some examples, the transceiver unit management module 760 can turn off at least one transceiver unit. For example, the transceiver unit other than the transceiver unit corresponding to each of the analog beams to be shaped may be turned off. For example, when it is determined that each of the to-be-shaped analog beams corresponds to m transceiver units, if L>m*B, (L-m*B) transceiver units are turned off.

For example, the transceiver unit management module 760 can turn off at least one transceiver unit when the number of analog beams to be shaped determined by the scheduling module 720 is less than the total number of antenna sub-arrays determined by the partitioning module 750. For example, when the number of scheduling users corresponding to each of the to-be-formed analog beams is less than a preset threshold, the transceiver unit management module 760 may determine that each of the to-be-shaped analog beams corresponds to a default number of transceiver units, and turn off the remaining transceiver units. .

In other examples, the transceiver unit management module 760 can increase the number of transceiver units corresponding to at least one analog beam to be shaped, such that each transceiver unit corresponds to one of the at least one analog beam to be shaped. For example, the transceiver unit management module 760 can use more transceiver units to transmit more analog beams to be shaped by the scheduling user.

In an embodiment, the sending module 740 is further configured to: before transmitting the data after shaping the hybrid beam to each scheduling user, send beam mode information to each user terminal, so that each user terminal according to beam mode information Determining whether to receive the data after the hybrid beamforming, wherein the beam mode information carries at least the identifier of the analog beam to be shaped.

In an embodiment, the BRS generating module 770 is configured to generate a first beamformed downlink reference signal BRS;

The sending module 740 is further configured to: send the first BRS generated by the BRS generating module 770 to the user terminal on the continuous or equally spaced frequency domain resources, so that the user terminal determines the analog beam identifier to be fed back according to the first BRS.

In an embodiment, the BRS generating module 770 is configured to generate a downlink after the second beamforming Reference signal BRS;

The sending module 740 is further configured to send the second BRS generated by the BRS generating module 770 to the scheduling user on the discontinuous time-frequency resource, while transmitting the data after the hybrid beam shaping to each scheduling user. And causing the scheduling user to feed back a beamformed channel quality to the base station according to the second BRS;

The receiving module 710 is further configured to receive a channel quality after beamforming;

The scheduling module 720 is further configured to: determine, according to the received channel-formed channel quality, whether the scheduled user is triggered to feed back the analog beam identifier to the base station.

FIG. 9 is a schematic structural diagram of a user terminal 900 according to an embodiment of the present invention. As shown in FIG. 9, the user terminal 900 includes:

The sending module 910 is configured to send an analog beam identifier to the base station, so that the base station determines the to-be-formed analog beam and the scheduled user corresponding to each to-be-shaped analog beam based on the simulated beam identifier, and generates for each analog beam to be shaped. Simulating beamforming weights, and calculating digital precoding weights for each scheduling user according to channel state information and analog beamforming weights of each scheduling user, according to analog beamforming weights and digital precoding weights for each Scheduling user data for hybrid beamforming;

The receiving module 920 is configured to receive the data after the hybrid beamforming sent by the base station.

FIG. 10 is a schematic structural diagram of a user terminal 1000 according to another embodiment of the present invention. As shown in FIG. 10, on the structure of the user terminal 900 shown in FIG. 9, the user terminal 1000 further includes a judging module 930, a selecting module 940, and a channel estimating module 950.

In an embodiment, the receiving module 920 is further configured to: receive beam mode information sent by the base station, where the beam mode information carries at least an identifier of the analog beam to be shaped;

The user terminal 900 further includes: a determining module 930, configured to determine, according to the beam mode information received by the receiving module 920, whether the data after the hybrid beamforming is received by the receiving module 920.

In an embodiment, the receiving module 920 is further configured to: receive the first beamformed downlink reference signal BRS sent by the base station;

The user terminal 900 further includes:

The selecting module 940 is configured to select an analog beam according to the first BRS received by the receiving module 920, and send the selected analog beam identifier to the base station by using the sending module 910.

In an embodiment, the receiving module 920 is further configured to: receive a second beamformed downlink reference signal BRS sent by the base station;

The channel estimation module 950 is configured to obtain a beamformed channel quality according to the second BRS received by the receiving module 920.

The sending module 910 is further configured to: send the channel-formed channel quality obtained by the channel estimation module 950 to the base station, so that the base station determines, according to the received channel-formed channel quality, whether the triggered user is required to feed back the simulated beam identifier to the base station. .

It should be noted that not all the steps and modules in the foregoing processes and the various structural diagrams are necessary, and some steps or modules may be omitted according to actual needs. The order of execution of each step is not fixed and can be adjusted as needed. The division of each module is only for the convenience of description of the functional division. In actual implementation, one module can be implemented by multiple modules, and the functions of multiple modules can also be implemented by the same module. These modules can be located in the same device. It can also be located in different devices. In addition, the use of "first" and "second" in the above description merely for the convenience of distinguishing two objects having the same meaning does not mean that there is a substantial difference.

The hardware modules in the embodiments may be implemented in a hardware manner or a hardware platform plus software. The above software includes machine readable instructions stored in a non-volatile storage medium. Thus, embodiments can also be embodied as software products.

In each case, the hardware may be implemented by specialized hardware or hardware that executes machine readable instructions. For example, the hardware can be a specially designed permanent circuit or logic device (such as a dedicated processor, Such as FPGA or ASIC) is used to perform specific operations. The hardware may also include programmable logic devices or circuits (such as including general purpose processors or other programmable processors) that are temporarily configured by software for performing particular operations.

The machine readable instructions corresponding to the modules in the figures may cause an operating system or the like operating on a computer to perform some or all of the operations described herein. The non-transitory computer readable storage medium may be inserted into a memory provided in an expansion board within the computer or written to a memory provided in an expansion unit connected to the computer. The CPU or the like installed on the expansion board or the expansion unit can perform part and all of the actual operations according to the instructions.

The non-transitory computer readable storage medium includes a floppy disk, a hard disk, a magneto-optical disk, an optical disk (such as a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD-RW, a DVD+RW), and a magnetic tape. , non-volatile memory card and ROM. Alternatively, the program code can be downloaded from the server computer by the communication network.

In conclusion, the scope of the claims should not be limited to the embodiments in the examples described above, but the description should be construed as a whole and the broadest explanation.

Claims

A hybrid beamforming method is applied to a base station, and the method includes:

Receiving an analog beam identifier fed back by the user terminal;

Determining an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam based on the analog beam identification;

Generating an analog beamforming weight for each analog beam to be shaped, and calculating a digital precoding weight for each scheduling user according to channel state information of each scheduling user and the analog beam shaping weight; and

And performing hybrid beamforming on the data of each scheduled user according to the analog beamforming weight and the digital precoding weight, and transmitting the mixed beamformed data to each scheduling user.
The method of claim 1 further comprising:

Determining, according to the determined number of analog beams to be shaped, the number of transceiver units corresponding to each analog beam to be shaped;

The transmitting the data after the hybrid beamforming to each scheduling user includes: transmitting the data after the hybrid beam shaping to each scheduling user by using the transceiver unit corresponding to the to-be-formed analog beam.
The method of claim 2, further comprising:

Dividing the antenna array into at least one antenna sub-array, each antenna sub-array being connected to at least one transceiver unit;

Determining, according to the determined number of to-be-shaped analog beams, the number of the transceiver units corresponding to each of the to-be-shaped analog beams includes: when the number of the to-be-formed analog beams is smaller than the total number of the antenna sub-arrays,

Determining that each of the analog beams to be shaped corresponds to at least one transceiver unit, and turning off at least one transceiver unit, or

And increasing the number of the transceiver units corresponding to the at least one analog beam to be shaped, such that each transceiver unit corresponds to one of the at least one analog beam to be shaped.
The method according to claim 3, wherein the transmitting the data after the hybrid beamforming is sent to each scheduling user by using the transceiver unit corresponding to the to-be-formed analog beam comprises:

Determining, according to each transceiver unit corresponding to the analog beam to be shaped, a correspondence between the to-be-formed analog beam and the antenna sub-array;

The data after the hybrid beamforming is sent to each scheduling user by using a multiplexing manner according to the corresponding relationship.
The method according to claim 4, wherein the multiplexing mode is Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), Space Division Multiplexing (SDM), and any combination thereof.
The method according to any one of claims 1 to 5, further comprising:

Before transmitting the data after the hybrid beamforming to each scheduling user, sending beam mode information to each user terminal, so that each user terminal determines whether to receive the data after the hybrid beamforming according to the beam mode information, The beam mode information carries at least the identifier of the analog beam to be shaped.
The method according to any one of claims 1 to 5, further comprising:

Generating a first beamformed downlink reference signal BRS;

Transmitting the first BRS to the user terminal on a continuous or equally spaced frequency domain resource, so that the user terminal determines an analog beam identifier to be fed back according to the first BRS.
The method according to claim 7, wherein the generating the first BRS comprises: performing analog beamforming on the downlink reference signal to obtain the first BRS.
The method according to any one of claims 1 to 5, further comprising:

Generating a second beamformed downlink reference signal BRS;

Transmitting the data of the hybrid beam to each of the scheduling users, and transmitting the second BRS to the scheduling user on the discontinuous time-frequency resource, so that the scheduling user according to the second BRS Transmitting, by the base station, a channel quality after beamforming;

Determining, according to the channel quality after the beamforming, whether the scheduling user is triggered to feed back the analog beam identifier to the base station.
The method according to claim 9, wherein the generating the second BRS comprises: performing hybrid beamforming on the downlink reference signal to obtain the second BRS.
A base station, comprising:

a receiving module, configured to receive an analog beam identifier fed back by the user terminal;

a scheduling module, configured to determine, according to the simulated beam identifier received by the receiving module, an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam;

The hybrid beamforming module is configured to generate an analog beamforming weight for each to-be-shaped analog beam, and calculate and calculate the weight according to the channel state information of each scheduling user and the simulated beam. a digital precoding weight, which performs hybrid beamforming on data of each scheduled user according to the analog beamforming weight and the digital precoding weight; and

And a sending module, configured to send the data after the hybrid beamforming to each scheduling user.
The base station according to claim 11, further comprising:

The transceiver unit management module is configured to determine, according to the determined number of analog beams to be shaped, the number of transceiver units corresponding to each analog beam to be shaped.
The base station according to claim 12, further comprising:

a dividing module, configured to divide the antenna array into at least one antenna sub-array, each antenna sub-array being connected to at least one transceiver unit;

The transceiver unit management module is configured to: when the number of the to-be-formed analog beams determined by the scheduling module is smaller than the total number of antenna sub-arrays determined by the dividing module, determine that each of the to-be-formed analog beams corresponds to at least one transceiver unit And turning off at least one transceiver unit, or increasing the number of transceiver units corresponding to at least one analog beam to be shaped, such that each transceiver unit corresponds to one of the at least one analog beam to be shaped.
The base station according to any one of claims 11 to 13, wherein the transmitting module is further configured to: send the data after shaping the hybrid beam to each user terminal before transmitting the data after shaping the beam And beam mode information, so that each user terminal determines, according to the beam mode information, whether to receive the data after the hybrid beamforming, wherein the beam mode information carries at least the identifier of the analog beam to be shaped.
The base station according to any one of claims 11 to 13, further comprising:

a BRS generating module, configured to generate a downlink reference signal BRS after the first beamforming;

The sending module is further configured to: send the first BRS to the user terminal on a continuous or equally spaced frequency domain resource, so that the user terminal determines, according to the first BRS, an analog beam to be fed back Logo.
The base station according to any one of claims 11 to 13, further comprising:

a BRS generating module, configured to generate a second beamformed downlink reference signal BRS;

The sending module is further configured to: send the second BRS to the scheduling user on the discontinuous time-frequency resource, and send the data after the hybrid beam shaping to each scheduling user, so that the scheduling Transmitting, by the user, the beam shaping to the base station according to the second BRS Channel quality;

The receiving module is further configured to receive the channel quality after the beamforming;

The scheduling module is further configured to determine, according to the channel quality after the beamforming, whether the scheduling user is triggered to feed back the analog beam identifier to the base station.
A user terminal, comprising:

a sending module, configured to send an analog beam identifier to the base station, so that the base station determines, according to the simulated beam identifier, an analog beam to be shaped and a scheduling user corresponding to each to-be-shaped analog beam, for each to-be-formed simulation Beams, generating analog beamforming weights, and calculating digital precoding weights for each scheduling user according to channel state information of each scheduling user and the analog beamforming weights, according to the analog beamforming weights The digital precoding weights perform hybrid beamforming on data of each scheduled user;

And a receiving module, configured to receive the data after the hybrid beamforming sent by the base station.
The user terminal according to claim 17, wherein the receiving module is further configured to: receive beam mode information sent by the base station, where the beam mode information carries at least an identifier of the analog beam to be shaped;

The user terminal further includes:

The determining module is configured to determine, according to the beam mode information, whether to receive the data after the hybrid beamforming.
The user terminal according to claim 17, wherein the receiving module is further configured to: receive a first beamformed downlink reference signal BRS sent by the base station;

The user terminal further includes:

And a selecting module, configured to select an analog beam according to the first BRS, and send, by using the sending module, the selected analog beam identifier to the base station.
The user terminal according to claim 17, wherein said receiving module Further for: receiving a second beamformed downlink reference signal BRS sent by the base station;

The user terminal further includes:

a channel estimation module, configured to obtain a channel quality after beamforming according to the second BRS estimation;

The sending module is further configured to: send the beam-formed channel quality to the base station, so that the base station determines, according to the beam-formed channel quality, whether the scheduling user is triggered to feed back to the base station. The analog beam identification.