User matching and power distribution methods for MIMO-NOMA downlink communication system

Patent metadata

Field	Value
Publication number	US-12191940-B2
Application number	US-202017789634-A
Country	US
Kind code	B2
Filing date	Feb 21, 2020
Priority date	Feb 12, 2020
Publication date	Jan 7, 2025
Grant date	Jan 7, 2025

Abstract

A user matching and power distribution methods for a MIMO-NOMA downlink communication system is provided. The user matching method includes: dividing all users into a strong user group and a weak user group according to a channel gain sorting result; and sequentially selecting a user in the strong user group, calculating a correlation coefficient between the user and each user in the weak user group, selecting a weak user with the highest correlation coefficient as a weak user in a cluster where the strong user is located, and excluding matched users from respective user groups, until the matching between all strong users and weak users are completed. The present invention enables weak users in a cluster to experience less inter-cluster interference in scenarios where the channel correlation between users is relatively low, thereby improving the total throughput of the communication system.

First claim

What is claimed is:

1. A user matching method for a MIMO-NOMA downlink communication system, comprising the following steps:
sorting respective channel gains of users, if a total number of the users is not an even number, directly excluding a user with the lowest channel gain to exclusively share a channel, and equally dividing all the users into a strong user group and a weak user group according to a channel gain sorting result, wherein a group with a larger channel gain is the strong user group, and a group with a smaller channel gain is the weak user group; and
sequentially selecting a user in the strong user group, and calculating a correlation coefficient between the user and each user in the weak user group, if the correlation coefficient is greater than or equal to a preset threshold, selecting a weak user with the highest correlation coefficient as a weak user in a cluster where the strong user is located, and excluding matched users from respective user groups, until the matching between all strong users and weak users are completed,
if the correlation coefficients of all matching combinations are less than the preset threshold, the matching of the cluster where the users of the selected strong user group is located is skipped; and after the matching process is completed, the remaining users of the weak user group are sequentially selected as weak users of an unmatched cluster.

2. The user matching method for a MIMO-NOMA downlink communication system according to claim 1 , wherein an expression for calculating the correlation coefficient between users is as follows:

γ

i
,
j

=

Cov
⁡
(

h
i

,

h
j

)

D
⁡
(

h
i

)

⁢

D
⁡
(

h
j

)

wherein h i and h j are channel gain vectors of an i th user and a j th user, respectively, Cov(h i ,h j ) is a covariance of h i and h j , and D(h i ) and D(h j ) are variances of h i and h j , respectively.

3. A power distribution method for a MIMO-NOMA downlink communication system, comprising:
sorting respective channel gains of users, if a total number of the users is not an even number, directly excluding a user with the lowest channel gain to exclusively share a channel, and equally dividing all the users into a strong user group and a weak user group according to a channel gain sorting result, wherein a group with a larger channel gain is the strong user group, and a group with a smaller channel gain is the weak user group;
sequentially selecting a user in the strong user group, and calculating a correlation coefficient between the user and each user in the weak user group, if the correlation coefficient is greater than or equal to a preset threshold, selecting a weak user with the highest correlation coefficient as a weak user in a cluster where the strong user is located, and excluding matched users from respective user groups, until the matching between all strong users and weak users are completed; and
distributing a preset transmit power to each cluster, and distributing a transmit power to strong users and weak users in the cluster, wherein a power distribution factor an, 1 of the strong users satisfies the following power distribution conditions:

max

α

n
,
1

(

R

n
,
1

+

R

n
,
2

)

s
.
t
.

R

n
,
1

≥

R

n
1

,

conv
-
BF

R

n
,
2

≥

R

n
2

,

conv
-
BF

0
≤

α

n
,
1

≤
1

,

wherein R n,1 is a data rate of strong users in a cluster n, R n,2 is a data rate of weak users in the cluster n; R n 1 ,conv-BF is a rate threshold of strong users in a MIMO-OMA system under the same conditions, and R n 2 ,conv-BF is a rate threshold of weak users in the MIMO-OMA system under the same conditions.

4. The power distribution method for a MIMO-NOMA downlink communication system according to claim 3 , wherein an objective function is established by using a Lagrange multiplier method, and the power distribution factor is solved by using a KKT condition, wherein an expression of the objective function is as follows:
L (α n,1 ,μ,γ)=−ƒ(α n,1 )+μ g (α n,1 )+γ h (α n,1 ),

where μ and γ are introduction parameters,

{

f
⁡
(

Assignees

• Univ Nanjing Posts & Telecommunications

Inventors

• Lu Yin
• Qu Yihuang
• Yang Chuying
• Li Taosen
• Wang Xiumei
• Zhu Hongbo

Classifications

• H04L25/03331

  Arrangements for the joint estimation of multiple sequences · CPC title

• H04B7/0452

  Multi-user MIMO systems · CPC title

• H04B7/0426 Primary

  Power distribution · CPC title

• H04B7/0413 Primary

  MIMO systems · CPC title