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 powerdomain 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 cochannel 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 25dB 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.