Performance analysis of MIMO-assisted HPMA networks over keyhole effect

As an innovative multiple access technology, hybrid power-frequency multiple access (HPMA) effectively supports massive connectivity while eliminating the decoding complexity associated with successive interference cancellation (SIC). Concurrently, although the keyhole effect represents a critical propagation degradation that drastically reduces diversity gains in wireless channels, its impact on advanced multiple-access techniques remains largely explored. Driven by these considerations, this paper investigates a comprehensive performance evaluation of a multiple-input multiple-output (MIMO)-assisted HPMA framework deployed over keyhole Nakagami- m fading environments. Specifically, exact closed-form formulations of outage probability (OP), ergodic capacity (EC), and average bit error rate (ABER) are derived, supplemented by high signal-to-noise ratio (SNR) asymptotic expansions to yield deeper engineering insights. Monte Carlo simulations verify the exactness of the theoretical analysis and demonstrate the resilience of the proposed HPMA system under realistic keyhole fading scenarios. Our findings reveal that HPMA maintains high performance under severe keyhole conditions, attaining substantial performance superiorities over standard non-orthogonal multiple access (NOMA), particularly regarding outage behavior and error rates. Finally, this study highlights HPMA as a promising, low-complexity, and resource-efficient radio access technology for next-generation wireless communications subjected to keyhole propagation constraints.