On the leakage-rate performance of untrusted relay-aided NOMA under co-channel interference

This study seeks an answer for the impact of the co-channel interference on the leakage rate of illegitimate relay-assisted power-domain non-orthogonal multiple access (NOMA) networks. The power-domain NOMA-based uni-/bi-directional information exchange through an illegitimate half-/full-duplex relay is adopted in the system model. Moreover, a limited number of co-channel interferers and friendly jammers are affected by the illegitimate relay in the network. Extensive computer simulations, analytical, and asymptotic results reveal that as the illegitimate relay is affected by a limited number of friendly jammers and co-channel interferers, its achievable rate cannot be enhanced and saturates at high signal-to-noise ratio. Results also show that the co-channel interference causes system coding gain losses on the users’ outage performance. In addition, the illegitimate relay remains active between - 10 and 25 dB for uni-/bi-directional information exchange. After 25 dB, the illegitimate relay saturates and experiences outages. Additionally, the order of decoding also impacts the illegitimate relay’s performance.