Impedance and Power Domains Integrated NOMA for Scalable User Pairing

This paper proposes a novel impedance and power domains integrated non-orthogonal multiple access (IP-NOMA) designed to increase the number of users supported in a user pairing. The proposed IP-NOMA leverages the coexistence and independence of power domain NOMA (PD-NOMA) and impedance domain (ID-NOMA). The system model incorporates power allocation (PA) and impedance-matching circuit (IMC) selections at the base station (BS) to effectively distinguish the domains. Imaginary IMC coefficients are employed at the receiver to separate power-domain and impedance-domain signals by exploiting a 90° phase offset introduced by the reactive tuning of the IMC. The numerical results demonstrate that IP-NOMA achieves superior performance compared to PD-NOMA and ID-NOMA in terms of achievable rate (AR) and outage probability (OP). Especially, AR is 9 [bps/Hz] higher than that of ID-NOMA at 25 [dB]. Moreover, IP-NOMA mitigates the impact of imperfect impedance based power attenuation reinforcement (I-PAR) reflections, further validating its robustness and potential for next-generation wireless network.