Optimal Multichannel Slotted ALOHA for Deadline-Constrained Unicast Systems

This paper considers multichannel slotted ALOHA for unicast in an ad hoc network. Under a deadline-constrained scenario that a packet is required to be transmitted to an intended recipient within a strict delivery deadline D (in unit of slot) and retransmission is not allowed, we obtain the optimal channel selection probabilities and the optimal transmission probability that maximize the reliability. In particular, the throughput maximization can be studied as the case of D = 1. Furthermore, by noting that there is a tradeoff between reliability and throughput when D > 1, we obtain the optimal schedule that maximizes the reliability subject to a throughput constraint and the one that maximizes the throughput subject to a reliability constraint.