Random access in wireless networks: how much aggressiveness can cause instability?

Random access schemes are simple and inherently distributed, yet capable of matching the optimal throughput performance of centralized scheduling algorithms. The throughput optimality however has been established for activation rules that are relatively sluggish, and may yield excessive queues and delays. More aggressive/persistent access schemes have the potential to improve the delay performance, but it is not clear if they can offer any universal throughput optimality guarantees. In this paper, we identify a limit on the aggressiveness of nodes, beyond which instability is bound to occur in a broad class of networks.