IEEE Transactions on Network Science and Engineering
Physical Layer Security of Jammer-Assisted Cooperative NOMA Network With Hardware Impairments and Non-Colluding /Colluding Eavesdroppers: Performance Analysis and Optimization
Nimi T., A. V. Babu
Abstract
This article explores various approaches to enhance the physical layer security performance of cooperative non-orthogonal multiple access (CNOMA) system, in scenarios involving multiple non-colluding or colluding eavesdroppers, taking into account residual hardware impairment (RHI) and imperfect successive interference cancellation conditions. Firstly, we propose a jamming-assisted (JA) framework for enhancing the physical layer security performance and derive analytical expressions for the secrecy outage probabilities (SOPs) of the downlink users and the system SOP (SSOP) of the CNOMA network for both JA and no-jammer (NJ) scenarios. It is illustrated that the proposed JA framework offers several key benefits: (i) a significant reduction in the SOPs and SSOP, (ii) a notable increase in system secrecy throughput (SST) and secrecy energy efficiency (SEE) for the network, and (iii) a complete alleviation of the zero-diversity order problem, if the transceivers are free of RHI. Following this, the optimal power allocation coefficients for the users at the base station and at the relay that independently as well as jointly minimize the SSOP of the JA-CNOMA network are determined. We demonstrate that the proposed approach results in: (i) considerable decrease of SSOP and SOPs and (ii) significant enhancement of SST and SEE of the JA-CNOMA network, compared to equal/random power allocation methods.