Performance Analysis of Downlink SWIPT-Based Cooperative NOMA in THz Band

The integration of non-orthogonal multiple access (NOMA) technology and terahertz (THz) technology shows great promise. However, considering the significant path loss of THz links, there may be scenarios where the base station is unable to establish links with remote users in NOMA systems. To address this issue, we consider a two-user NOMA system where the near user acts as a half-duplex relay, cooperating in the communication between the base station and the far user. In this setup, we utilize simultaneous wireless information and power transfer (SWIPT) technology to power the near user. To account for various practical factors, we take into consideration path loss,
$\alpha-\mu$
fading, pointing error, and transceiver hardware impairments (HIs). We derive the outage probability (OP) for NOMA users and system throughput. Additionally, we obtain the diversity gain of OP under high signal-to-noise ratio. Simulation results demonstrate the effectiveness of the presented performance analysis and reveal that the impact of HIs on OP performance is significant.