Antenna Selection in MIMO-NOMA Systems: A New Approach for Physical
Layer Security Enhancement
Abstract
Non-Orthogonal Multiple Access (NOMA) is known as a promising technology
for next-generation wireless communication networks. In this paper,
three low-complexity antenna selection schemes are proposed which aim to
enhance the physical layer security (PLS) of a multiple-input
multiple-output (MIMO) NOMA system. The system is composed of a single
transmitter, multiple legitimate users, and one eavesdropper, all
equipped with multiple antennas. The first scheme maximizes the secrecy
sum-rate (SSR) of the system when the eavesdropper’s channel state
information (CSI) is known, whereas the second scheme maximizes SSR in
the absence of CSI. In the third scheme, the emphasis shifts towards
fairness, aiming to maximize the minimum secrecy rate across all users.
Numerical results demonstrate that the performance of the first two
proposed schemes is very close to that of the optimal case, albeit with
much lower computational complexity. It is also observed that the third
scheme enhances fairness by balancing users’ secrecy rates, though with
a moderate decrease in the overall secrecy sum-rate.