Abstract
Associated with multi-packet reception at the access point, irregular repetition slotted ALOHA (IRSA) holds a great potential in improving the access capacity of massive machine type communication systems. This work investigates the packet repetition of the users in an IRSA-based random access system where the access point can simultaneously retrieve multiple packets in a slot. Specifically, we propose an analytical transmission probability distribution for IRSA with dual-packet reception capability. In addition, the energy efficiency optimization in terms of the maximum number of replica is also presented. Numerical results show that using the proposed transmission distribution for the replica can achieve a significant higher throughput than the existing benchmark distributions. With optimized repetition rate, the energy efficiency of users can be also improved remarkably.