Self-interference in Multi-hop Wireless Chains: Geometric Analysis and Performance Study

In the presence of interference, two single hop links can interact in a number of different ways, exhibiting significantly different behavior. In this paper, we consider the impact of these two-flow interactions on multi-hop chains. Specifically, we characterize the different types of interactions that arise in chains between hops that do not share a common node. We develop closed formed expressions to estimate the probability of occurrence of these interaction combinations. We use simulation to characterize the performance of the most common types of chains. We make a number of interesting observations: (1) the most destructive types of two-flow interactions do not arise commonly in chains; (2) the throughput of chains does not vary significantly with the types of arising interactions, because of the self-regulating effect of packets in the chain (later hops can only transmit when they receive packets from earlier ones); however, (3) the chains exhibiting destructive interactions suffer frequent collisions and require many more retransmissions. As such, in general scenarios, such chains reduce the available bandwidth within the network.