US 12,756,426 B2 · Wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access under complex channel conditions

Abstract

A wireless secure communication method based on RIS-NOMA under complex channel conditions, the method including: firstly, an intelligent surface is assume to be disposed between the base station and legitimate NOMA users, and between the base station and eavesdroppers; the signal to interference plus distortion noise ratio (SIDNR) for the legitimate NOMA user and the eavesdropper is calculated in the presence of RHI in the system; secondly, considering shadow fading and to simplify the overly complex calculation process, the probability density function and cumulative distribution function of the shadow fading are approximated; finally, the outage probability and intercept probability of the legitimate users and eavesdroppers are calculated.

A wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access (RIS-NOMA) under complex channel conditions, wherein the RIS-NOMA refers to a RIS-NOMA communication system comprises:

a base station (BS), a reconfigurable intelligent surface (RIS), a legitimate NOMA user, and an eavesdropper (Eve);
the legitimate NOMA user comprises a legitimate remote user Dm and a legitimate near user Dn, and the base station communicates with the RIS;
the RIS communicates with the legitimate NOMA user;
the Eve intercepts a signal transmitted by the RIS;
an arbitrary channel link obeys κ-μ shadow fading;
each node in the RIS-NOMA communication system encounters a residual hardware impairment (RHI);
the method comprising:
1) calculating a signal to interference plus distortion noise ratio (SIDNR) for the legitimate NOMA user and the eavesdropper in the presence of RHI in the RIS-NOMA communication system;
2) approximating a probability density function and cumulative distribution function for the κ-μ shadow fading;
3) calculating an outage probability of the legitimate NOMA user and an intercept probability of the eavesdropper;
and
4) Transforming a calculation of the outage probability of the legitimate NOMA user and the intercept probability of the eavesdropper into solving a cumulative distribution function of equivalent channel coefficients of corresponding joint channels, whereby measuring physical layer secure transmission performance of the system;
wherein:
1) is performed as follows:
defining a channel coefficient from the base station to an ith RIS reflecting surface in the system as hsi, and channel coefficients from the RIS to the legitimate NOMA user and to the eavesdropper as gidu, u∈(n,m) and gie, respectively;
when the legitimate near user Dn detects a weak signal xm, the signal to interference plus distortion to noise ratio SIDNR is expressed as:
γ
D
n
→
D
m
=
α
m
⁢
A
n
2
A
n
2
(
α
n
+
ρ
SD
n
2
)
+
d
B
τ
⁢
d
R
,
n
τ
ρ
S
;
(
1
)
wherein, αm and αn represent power distribution coefficients of the legitimate remote user Dm and the legitimate near user Dn, respectively, and
α
𝔫
<
α
m
,
α
m
+
α
n
=
1
;
ρ
S
=
P
S
σ
D
2
represents an average signal-to-noise ratio of a legal link, Ps is a transmit power of BS, and is an additive white Gaussian noise channel variance;
ρSDn represents an overall RHI level of a link BS→Dn;
A
n
=
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
h
si
❘
"\[RightBracketingBar]"
⁢
❘
"\[LeftBracketingBar]"
g
d
n
❘
"\[RightBracketingBar]"
represents a joint channel coefficient of the link BS→Dn;
hsi is a channel coefficient of a link BS→RIS;
gidn is a channel coefficient of a link RIS→Dn;
|⋅| represents modeling;
dB and dR,n represent a distance from the base station to the RIS and a distance from the RIS to the legitimate near user Dn, respectively;
and τ represents a path fading index;
through successive interference cancellation (SIC) technology, the SIDNR of Dn decoding its own signal is given by the following equation:
γ
D
n
=
α
n
⁢
A
n
2
A
n
2
⁢
ρ
SD
n
2
+
d
B
τ
⁢
d
R
,
n
τ
ρ
S
;
(
2
)
when Dm decodes its own signal, a signal xn with strong channel gain is considered as noise, and SIDNR is represented as follows:
γ
D
m
=
α
m
⁢
A
m
2
A
m
2
(
α
n
+
ρ
SD
m
2
)
+
d
B
τ
⁢
d
R
,
m
τ
ρ
S
;
(
3
)
wherein
A
m
=
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
h
si
❘
"\[RightBracketingBar]"
⁢
❘
"\[LeftBracketingBar]"
g
id
m
❘
"\[RightBracketingBar]"
;
g
id
m
is a channel coefficient of a link RIS→Dm;
when the eavesdropper intercepts the signals xn and xm respectively, the obtained SIDNR is expressed as follows:
γ
E
n
=
α
n
⁢
A
e
2
A
e
2
⁢
ρ
SE
2
+
d
B
τ
⁢
d
R
,
e
τ
ρ
E
(
4
)
γ
E
m
=
α
m
⁢
A
e
2
A
e
2
(
α
n
+
ρ
SE
2
)
+
d
B
τ
⁢
d
R
,
e
τ
ρ
E
(
5
)
ρ
E
=
P
S
σ
E
2
represents SNR of an eavesdropping link;
A
e
=
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
h
si
❘
"\[RightBracketingBar]"
⁢
❘
"\[LeftBracketingBar]"
g
ie
❘
"\[RightBracketingBar]"
;
gie represents a joint channel coefficient of a link
RIS
→
Eve
;
σ
E
2
represents an additive white Gaussian noise channel variance of the eavesdropper;
ρSE represents an overall RHI level of a link BS→Eve;
and dR,e represents a distance from the RIS to the eavesdropper;
and
2) is performed as follows:
SIDNR of the legitimate NOMA user and the eavesdropper contains
A
u
=
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
h
si
❘
"\[RightBracketingBar]"
⁢
❘
"\[LeftBracketingBar]"
g
d
iu
❘
"\[RightBracketingBar]"
,
u
∈
(
n
,
m
)
⁢
and
⁢
A
e
=
∑
i
=
1
N
❘
"\[LeftBracketingBar]"
h
si
❘
"\[RightBracketingBar]"
⁢
❘
"\[LeftBracketingBar]"
g
ie
❘
"\[RightBracketingBar]"
as equivalent channel coefficients for corresponding joint channels;
assuming that envelopes |hsi|, |gidu|, u∈(n,m) and |gie| of all instantaneous channel coefficients are subject to independent and identically distributed k-μ shadow fading, and X represents the envelopes |hsi|, |gidu|, u∈(n,m) and |gie| of instantaneous channel coefficients, the cumulative distribution functions and probability density functions thereof are represented as follows:
F
X
(
x
)
=
μ
μ
-
1
⁢
m
m
(
1
+
k
)
μ
Γ
⁡
(
μ
)
⁢
(
μ
⁢
k
+
m
)
m
⁢
(
1
R
)
2
⁢
μ
⁢

x
2
⁢
μ
⁢
Φ
2
(
μ
-
m
,
m
,
μ
+
1
;
-
μ
⁡
(
1
+
k
)
⁢
x
2
R
2
,
-
μ
⁡
(
1
+
k
)
R
2
⁢
mx
2
μ
⁢
k
+
m
)
(
6
)
f
X
(
x
)
=
2
⁢
μ
μ
⁢
m
m
(
1
+
k
)
μ
Γ
⁡
(
μ
)
⁢
(
μ
⁢
k
+
m
)
m
⁢
(
1
R
2
⁢
μ
)
⁢
x
2
⁢
μ
-
1
exp
⁡
(
-
μ
⁡
(
1
+
k
)
R
2
⁢
x
2
)
1
⁢
F
1
(
m
,
μ
;
μ
2
⁢
k
⁡
(
1
+
k
)
(
μ
⁢
k
+
m
)
⁢
R
2
⁢
x
2
)
=
2
⁢
a
μ
Γ
⁡
(
μ
)
⁢
b
m
⁢
x
2
⁢
μ
-
1
⁢
exp
⁡
(
-
ax
)
1
⁢
F
1
(
m
,
μ
;
μ
2
⁢
k
⁡
(
1
+
k
)
(
μ
⁢
k
+
m
)
⁢
R
2
⁢
x
2
)
(
7
)
Γ(⋅), Φ2(⋅) and 1F1(⋅) are defined as a Gamma function, binary confluence hypergeometric function, and confluence hypergeometric function, respectively;
a
=
μ
⁡
(
1
+
k
)
Ω
,
b
=
μ
⁢
k
+
m
m
;
k is a ratio of a total power of dispersed components to dominant sight components, μ is a total number of multipath clusters, m is a fading degree parameter, and R is an average power of the channel;
to simplify calculation, the cumulative distribution function and probability density function of the k-μ shadow distribution are approximated as follows:
F
X
(
x
)
≈
(
α
α
⁢
x
2
⁢
α
Γ
⁡
(
α
+
1
)
⁢
R
2
⁢
a
)
1
⁢
F
1
(
α
,
α
+
1
,
-
x
2
⁢
α
R
2
)
(
8
)
f
X
(
x
)
≈
2
⁢
α
α
⁢
x
2
⁢
α
-
1
R
2
⁢
α
⁢
Γ
⁡
(
α
)
⁢
exp
⁡
(
-
x
2
R
2
⁢
α
)
;
(
9
)
and
α
=
m
⁢
μ
⁡
(
1
+
k
)
2
m
+
μ
⁢
k
2
+
2
⁢
mk
.

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Wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access under complex channel conditions

Life of this patent

Wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access under complex channel conditions

Life of this patent

Abstract

Claims5