Downlink precoding method and base station

Patent metadata

Field	Value
Publication number	US-10211894-B2
Application number	US-201615744117-A
Country	US
Kind code	B2
Filing date	Jul 12, 2016
Priority date	Jul 14, 2015
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

Disclosed are a downlink precoding method and a base station. The method includes: configuring a first precoding mode for a first cell, wherein the first precoding mode includes information of a precoding matrix configured for each candidate user of the first cell on each resource; selecting a scheduling user on each resource from candidate users according to the first precoding mode; and performing precoding to a channel estimation signal and downlink data of the scheduling user according to a precoding matrix of the scheduling user, and transmitting precoded channel estimation signal and precoded downlink data to the scheduling user. Such method and base station of the present disclosure can reduce the feedback overhead of the user, effectively improve the accuracy of channel quality indicator (CQI) estimation, and improve the system throughput and user throughput.

First claim

The invention claimed is:

1. A downlink precoding method, comprising:
configuring a first precoding mode for a first cell, wherein the first precoding mode includes information of a precoding matrix configured for each candidate user of the first cell on each resource;
selecting a scheduling user on each resource from candidate users according to the first precoding mode;
performing precoding to a channel estimation signal and downlink data of the scheduling user according to a precoding matrix of the scheduling user, and transmitting precoded channel estimation signal and precoded downlink data to the scheduling user;
receiving a second precoding mode transmitted by an adjacent cell, wherein the second precoding mode includes information of a precoding matrix used by the adjacent cell on each resource;
the selecting the scheduling user on each resource from the candidate users according to the first precoding mode comprises:
with respect to each resource, determining candidate users on this resource and a first precoding matrix configured for each of the candidate users according to the first precoding mode;
determining a second precoding matrix used by the adjacent cell on this resource according to the second precoding mode;
calculating a throughput of each of the candidate users on the resource according to the first precoding matrix and the second precoding matrix; and
determining a candidate user with a maximum throughput as the scheduling user on the resource.

2. The method of claim 1 , wherein the calculating the throughput of each of the candidate users on the resource according to the first precoding matrix and the second precoding matrix and determining the candidate user with the maximum throughput as the scheduling user on the resource comprises:
dividing the candidate users on the resource in the first precoding mode into multiple user groups;
with respect to each user group, determining the first precoding matrix of each candidate user in the user group recorded in the first precoding mode;
calculating the throughput of each candidate user in the user group on the resource according to the first precoding matrix and the second precoding matrix;
adding the throughput of all candidate users in the user group, and determining a sum of the throughput of all candidate users as a throughput of the user group on the resource; and
determining the user group with a maximum throughput as the scheduling user on the resource.

3. The method of claim 1 , wherein the determining the second precoding matrix used by the adjacent cell on the resource according to the second precoding mode comprises:
searching for at least one precoding matrix configured for the resource in the second precoding mode, and determining a weighted sum of the at least one precoding matrix as the second precoding matrix.

4. The method of claim 1 , wherein the calculating the throughput of each of the candidate users on the resource according to the first precoding matrix and the second precoding matrix comprises:
calculating a received signal power of each candidate user according to the first precoding matrix;
calculating an inter-cell interference power between the first cell and the adjacent cell according to the first precoding matrix and the second precoding matrix; and
calculating a signal to interference and noise ratio according to the received signal power and the inter-cell interference power.

5. The method of claim 1 , wherein the configuring the first precoding mode for the first cell comprises:
determining a statistical channel characteristic of each candidate user on each resource;
configuring the precoding matrix for each candidate user according to the statistical channel characteristic; and
recording the information of the precoding matrix into the first precoding mode.

6. The method of claim 1 , wherein the transmitting the precoded channel estimation signal and the precoded downlink data to the scheduling user comprises:
transmitting the precoded channel estimation signal to the scheduling user;
after receiving a channel quality indicator fed back by the scheduling user according to the received precoded channel estimation signal, transmitting the precoded downlink data to the scheduling user.

7. A base station, comprising:
a processor;
a memory; wherein
the memory stores instructions executable by the processor that, when executed by the processor, cause the processor to:
configure a first precoding mode for a first cell, wherein the first precoding mode records information of a precoding matrix of each candidate user on each resource;
select a scheduling user from candidate users for each resource according to the first precoding mode;
perform precoding to a channel estimation signal and downlink data of the scheduling user according to a precoding matrix of the scheduling user; and
transmit precoded channel estimation signal and precoded downlink data to the scheduling user;
receive a second precoding mode transmitted by an adjacent cell, wherein the second precoding mode records information of a precoding matrix used by the adjacent cell on each resource;
the instructions cause the processor to select the scheduling user further cause the processor to:
determine, with respect to each resource, candidate users configured on the resource and a first precoding matrix configured for each of the candidate users according to the first precoding mode, and determine a second precoding matrix used by the adjacent cell on the resource according to the second precoding mode;
calculate a throughput of each of the candidate users on the resource according to the first precoding matrix and the second precoding matrix; and
determine a candidate user with a maximum throughput as the scheduling user on the resource.

8. The base station of claim 7 , wherein the instructions that cause the processor to determine the candidate users on the resource and the second proceding matrix further cause the processor to: divide the candidate users on the resource in the first precoding mode into multiple user groups, with respect to each user group, determine the first precoding matrix of each candidate user in the user group recorded in the first precoding mode;
the instructions that cause the processor to calculate the throughput of each of the candidate users further cause the processor to: calculate the throughput of each candidate user on the resource according to the first precoding matrix and the second precoding matrix, add throughputs of all candidate users in the user group, and determine a sum of the throughputs as a throughput of the user group on the resource;
the instructions that cause the processor to determine the scheduling user further cause the processor to: determine the user group with a maximum throughput as the scheduling user on the resource.

9. The base station of claim 7 , wherein the instructions that cause the processor to determine the candidate users on the resource and the second precoding matrix further cause the processor to: search for at least one precoding matrix configured for the resource in the second precoding mode, and determine a weighted sum of the at least one precoding matrix as the second precoding matrix.

10. The base station of claim 7 , wherein the instructionst that cause the processor to calculate the throughput of each of the candidate users further cause the processor to: calculate a received signal power of each candidate user according to the first precoding matrix, calculate an inter-cell interference power between the first cell and the adjacent cell according to the first precoding matrix and the second precoding matrix, and calculate a signal t

Assignees

• Ntt Docomo Inc

Inventors

• Lan Yang
• Li Anxin
• Jiang Huiling

Classifications

• H04B7/0632

  Channel quality parameters, e.g. channel quality indicator [CQI] · CPC title

• H04B7/0456 Primary

  Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting · CPC title

• H04W72/1273

  of downlink data flows · CPC title

• H04B7/0413 Primary

  MIMO systems · CPC title

• H04B7/0452

  Multi-user MIMO systems · CPC title