An optimal stopping strategy for opportunistic broadcast channel access

Opportunistic routing with network coding (NCOR) has recently emerged as a promising unicast paradigm in lossy wireless multihop networks. By combining the multi-user diversity advantage of the broadcast links and the erasure-codes property of random network coding, it raises an interesting question on the broadcast channel access control algorithm, since the reliability is guaranteed by upper-layer coding and thus it is not necessary to wait for all the receivers to be ready. In this paper, we formalize it as the opportunistic broadcast channel access control problem. By appealing to the theory of optimal stopping, we develop a strategy which can balance between the access delay and instantaneous delivery ability of the broadcast link. This strategy turns out to be a threshold-based policy, which allowing fully distributed implementation. Simulation results show that the proposed strategy outperforms existing schemes significantly in terms of end to end throughput under various traffic loads.