Per-Replica Power Diversity in Grant-Free Multiple Access: Design and Performance Evaluation

Abstract

This work presents the concept of power replica diversity applied to grant-free multiple access, where users access the channel following contention resolution diversity slotted ALOHA protocol (CRDSA). We study a system where users can transmit two replicas at two different power levels, maintaining a constant level of energy consumption. The receiver’s performance is determined by a threshold-based capture effect. We demonstrate how varying the power levels of replicas can impact performance in terms of throughput, packet loss rate, and spectral efficiency. To evaluate the maximum system load supported by the most advantageous power levels, we analyze the asymptotic case of infinitely long frames. The results show that the proposed technique outperforms CRDSA in terms of both throughput and packet loss rate while achieving a higher spectral efficiency, considering fixed energy consumption.