An analytical model for multi-group slotted ALOHA with capture

The performance of multi-group slotted ALOHA with capture improves dramatically over single-group slotted ALOHA. An analytical model is proposed to evaluate the throughput, delay, and stability of a multi-group slotted ALOHA system with capture. The model approximates a K-group system as K interactive slotted ALOHA systems with independent Bernoulli jamming sources. An iterative procedure is used to find the parameters of the Bernoulli jamming sources. The fairness among groups is improved by assigning different retransmission probabilities to different groups. More balanced throughput and delay can be achieved. In the case that the total input traffic exceeds the system capacity, it might not necessarily lead to the total collapse of the whole system. High-power groups may have acceptable throughput due to the capture effect. The model can be used to evaluate a mobile slotted ALOHA network where the near-far effect approximately divides users into groups with multi-level power.