Towards Throughput and Delay Optimal Routing for Wireless Ad-Hoc Networks

The design of routing protocols for wireless ad-hoc networks is guided by the dual requirements of throughput optimality and minimum delay. Lately, there has been a movement from the traditional routing approach, which identifies a best path to the destination before transmission and routes all the packets through it, to opportunistic approaches which make routing decisions adaptively based on actual transmission outcomes. We compare the stable rate region of both the approaches and find, interestingly, that opportunistic routing schemes do not always support a larger stable-rate region than traditional routing protocols. Backpressure based schemes are known to be throughput optimal but compromise on delay performance instead. We study the behavior of various schemes and propose a routing policy that considers both the goals of throughput optimality and minimizing expected delay in its design.