The close relationship between multiple access technologies and efficient spectrum utilization makes power- domain non-orthogonal multiple access (NOMA) an attractive solution that enables the support of high data rates, user fairness and low-latency communications in 5G and next generation networks. However, user pairing and successive interference cancelation applied in NOMA facilitates eavesdropping on the far user’s signal by the near user establishing security as a main issue in NOMA systems. Due to their numerous advantages, the means of physical layer security (PLS) are extremely suitable to combat internal NOMA eavesdropping. Up to the present only a few studies exist which examine different PLS approaches against eavesdropping on the far user by the near user. Among them are a joint beamforming and power allocation algorithm, an angle conversion method that alters the original signal constellation before transmission, and a directional modulation approach. In this paper, the available PLS methods against eavesdropping on the far user by the near user are investigated and the main advantages and drawbacks of these methods are compared.

1.
F.-L.
Luo
and
C.
Zhang
, “Non-Orthogonal Multiple Access (NOMA): Concept and Design,” in
Signal Processing for 5G: Algorithms and Implementations
,
Wiley-IEEE Press
,
2016
, pp.
143
168
.
2.
D.
Mihaylova
,
V.
Stoynov
,
A.
Ivanov
,
Z.
Valkova-Jarvis
, “
An Overview of Methods to Combat Eavesdropping in NOMA-based Networks through Physical Layer Security
,” in
IOP Conference Series: Materials Science and Engineering
,
2021
, vol.
1032
, pp.
1
6
.
3.
D.
Xu
,
P.
Ren
,
Q.
Du
,
L.
Sun
,
Y.
Wang
, “
Combat eavesdropping by full-duplex technology and signal transformation in non-orthogonal multiple access transmission
,”
2017 IEEE International Conference on Communications (ICC)
, (
IEEE
,
Paris
,
2017
) pp.
1
6
.
4.
R.
Christopher
,
D.
Borah
, “
Physical Layer Security for Weak User in MISO NOMA Using Directional Modulation (NOMAD
),”
IEEE Communications Letters
, May
2020
, vol.
24
, no.
5
, pp.
956
960
.
5.
K.
Cao
,
B.
Wang
,
H.
Ding
,
T.
Li
,
J.
Tian
and
F.
Gong
, “
Secure Transmission Designs for NOMA Systems Against Internal and External Eavesdropping
,” in
IEEE Transactions on Information Forensics and Security, (IEEE)
, vol.
15
, pp.
2930
2943
.
6.
C.
Zhang
,
F.
Jia
,
Z.
Zhang
,
J.
Ge
and
F.
Gong
, “
Physical Layer Security Designs for 5G NOMA Systems With a Stronger Near-End Internal Eavesdropper
,” in
IEEE Transactions on Vehicular Technology, (IEEE
,
2020
), vol.
69
, no.
11
, pp.
13005
13017
.
This content is only available via PDF.
You do not currently have access to this content.