Opportunistic Routing with Congestion Diversity in Wireless Ad-hoc Networks

TL;DR

This paper introduces D-ORCD, a distributed opportunistic routing protocol that balances shortest path and congestion-aware routing to ensure bounded delay and improve performance in wireless ad-hoc networks.

Contribution

It develops a systematic, congestion-aware routing policy combining shortest path and backpressure concepts, with practical implementation and empirical validation.

Findings

D-ORCD ensures bounded expected delay in all network conditions.

Simulation results show significant delay reduction compared to existing methods.

Practical implementation optimizes parameters for real-world wireless networks.

Abstract

We consider the problem of routing packets across a multi-hop network consisting of multiple sources of traffic and wireless links while ensuring bounded expected delay. Each packet transmission can be overheard by a random subset of receiver nodes among which the next relay is selected opportunistically. The main challenge in the design of minimum-delay routing policies is balancing the trade-off between routing the packets along the shortest paths to the destination and distributing traffic according to the maximum backpressure. Combining important aspects of shortest path and backpressure routing, this paper provides a systematic development of a distributed opportunistic routing policy with congestion diversity ({D-ORCD}). {D-ORCD} uses a measure of draining time to opportunistically identify and route packets along the paths with an expected low overall congestion. {D-ORCD} is proved to ensure a bounded expected delay for all networks and under any admissible traffic. Furthermore, this paper proposes a practical implementation which empirically optimizes critical algorithm parameters and their effects on delay as well as protocol overhead. Realistic Qualnet simulations for 802.11-based networks demonstrate a significant improvement in the average delay over comparative solutions in the literature. %Finally, various practical modifications to {D-ORCD} are proposed and their performance are evaluated.