Performance Analysis of Partial Power‐Frequency Multiple Access for Multi‐Antenna Satellite‐Terrestrial Communications

ABSTRACT This paper investigates a partial power‐frequency multiple access (PFMA) framework for two‐user multi‐antenna satellite‐terrestrial downlink communications. The proposed PFMA protocol combines power‐domain superposition in one bandwidth portion with an additional orthogonal bandwidth portion for the second user. This structure improves spectrum utilization while avoiding multistage successive interference cancellation (SIC) at the ground terminals. The satellite is equipped with multiple transmit antennas to enhance link reliability through spatial diversity, whereas both terrestrial users employ single receive antennas. Considering Shadowed‐Rician fading channels, we derive closed‐form expressions for the outage probability (OP) and ergodic capacity (EC) under an equivalent aggregate PFMA signal‐to‐interference‐plus‐noise ratio model. High‐SNR approximations are further developed to reveal the diversity order and capacity ceilings imposed by the power‐frequency allocation coefficients. Numerical and Monte Carlo simulation results confirm the analytical derivations and show that the proposed PFMA scheme can provide reliability and spectral‐efficiency gains over conventional orthogonal multiple access (OMA) and non‐orthogonal multiple access (NOMA) benchmark schemes under the same total transmit‐power and bandwidth budgets.