Modeling of two-flow interactions under SINR model in Multi-hop Wireless Networks

Carrier Sense Multiple Access (CSMA) protocols in Multi-hop Wireless Networks (MHWN) are known to suffer from different forms of hidden and exposed terminal problems, leading to inefficiency and unfairness. Recent studies have formally characterized the fundamental interactions in the IEEE 802.11 protocol by classifying and quantifying the possible interactions that arise between two interfering single hop links. However, existing studies use a simple disc based propagation model, which does not model the effect of interference accurately in the presence of capture. This paper advances this line of study by developing the analysis and performance models for the two-flow interference problem using a Signal-to-Interference-Noise (SINR) based propagation model with large scale fading. This model has been experimentally shown to accurately predict the performance in wireless testbeds. The analysis identifies four previously unknown categories of interactions, and affects the probability of occurrence of the other categories. Moreover, using a SINR model allows us for the first time to characterize the incidence of the exposed terminal problem. The paper proposes closed form expressions to estimate the probability of occurrence of each category. We then propose throughput estimation models for the frequently occurring new categories and validate them against simulation. We believe that collectively these contributions provide a substantial improvement in our understanding of the effect of interference from first principles, which is a vital step in developing protocols that account for it.