Energy efficiency optimization method for IRS-assisted NOMA THz network

Patent metadata

Field	Value
Publication number	US-12348985-B2
Application number	US-202217882620-A
Country	US
Kind code	B2
Filing date	Aug 8, 2022
Priority date	Jun 15, 2022
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

An energy efficiency optimization method for an IRS-assisted NOMA THz network comprises: classifying users into BS users and IRS users; defining a channel model for the BS users and a channel model for the IRS users; calculating a BS user rate and an IRS user rate respectively, and calculating a total rate of a system; proposing an optimization problem for downlink power control and IRS phase shift adjustment; and solving the optimization problem through an MADRL method. The invention puts forward an energy efficiency concept and adopts an MADRL method to maximize the overall energy efficiency of the system under the constraints of minimum rate and maximum power of each user.

First claim

What is claimed is:

1. An energy efficiency optimization method for an IRS-assisted NOMA THz network, comprising the following steps:
Step 1: classifying users into BS users and IRS users;
Step 2: defining a channel model for the BS users and a channel model for the IRS users;
Step 3: calculating a BS user rate and an IRS user rate respectively, and calculating a total rate of a system;
Step 4: proposing an optimization problem for downlink power control and IRS phase shift adjustment; and
Step 5: solving the optimization problem through an MADRL method.

2. The energy efficiency optimization method for an IRS-assisted NOMA THz network according to claim 1 , wherein in Step 1,
N B antennas are configured for a base station, N U antennas are configured for users and the users are classified into BS users and IRS users; assume the number of the BS users is L, the BS users is represented by a set ={1, 2 . . . , L}; the IRS users are divided into M clusters, wherein each cluster comprises K users and is served by G IRS elements, and ={1, 2, . . . M} ={1, 2, . . . G}, {1, 2, . . . K}; a bandwidth of the system is divided into multiple sub-channels, wherein each BS user and each IRS user respectively use one sub-channel, and assume the BS users use the first L sub-channels, IRS users use the remaining sub-channels.

3. The energy efficiency optimization method for an IRS-assisted NOMA THz network according to claim 1 , wherein in Step 2, the channel model for the BS users is specifically as follows:
considering that a THz channel from a BS to users is modeled into a LoS path with the neglect of the reflected, scattered and diffracted fading due to severe attenuation of THz; a channel gain from the BS to a user l at a sub-channel n is expressed as:

h

l
,
n

B

=

1

PL
⁡
(

f
n

,

d
l

)

wherein, PL(f n , d l ) is a path loss of the THz LoS path, and f n and d l are a THz frequency and a distance between the BS and the user; the path loss of the THz LoS path is formed by two parts, of which one is a free space spreading loss and the other is a molecular absorption loss, with an expression as:
PL ( f n ,d l )= L spread ( f n ,d l )× L abs ( f n ,d l )

where, L spread (f n , d l ) and L abs (f n , d l ) meet:

L
spread

(

f
n

,

d
l

)

=

(

4
⁢
π
⁢

f
n

⁢

d
l

c

)

2

⁢

L
abs

(

f
n

,

d
l

)

=

e

-

k
abs

(

f
n

)

⁢

d
l

where, c represents a speed of light, and k abs (f n ) represents molecular absorption coefficient;
assume power transmitted to the user i through the sub-channel n is p l,n B , a received signal is:

y

l
,
n

B

=

h

l
,
n

B

⁢

p

l
,
n

B

+

h

l
,
n

B

⁢

∑

l
′

=
1

,

l
′

≠
l

L

∑

n
′

=

n
-
1

,

n
′

Assignees

• Univ Dongguan Technology

Inventors

• Zhang Guobin
• Chen Han
• Li Haibin
• Zhu Pengcheng

Classifications

• H04W52/242

  taking into account path loss · CPC title

• H04W52/143

  Downlink power control · CPC title

• H04L5/0005

  Time-frequency · CPC title

• H04B7/145

  Passive relay systems · CPC title

• H04B7/15528

  Control of operation parameters of a relay station to exploit the physical medium · CPC title