Abstract—Chains or multi-hop paths are the fundamental communicationstructureinMulti-HopWirelessNetworks.Understandingchainbehavioriscriticalinordertobuildeffective higherlayerprotocols.Thispaperexaminestheproblemofhow MAC level interactions influence chain behavior in a general multi-hopwirelessnetworkwheremultiplechainscoexist.We first classify chains based on the MAC interactions observed between its hops when there is no external traffic. Then we identify the interactions across two interfering chains for the mostcommoncategoriesofchains.Westudytheprobabilityof occurrence,andestimatetheeffectofMACinteractionsonthe performanceofthechains.Wealsoshowthatdifferentchains exhibit different transmission patterns; this is an effect that is necessary for accurately estimating chain performance. We observethatdestructiveinteractionsarisemorefrequentlyamong twointerferingchainsthantheydowithinasinglechain.Moreover,chainsthathavehiddenterminalsduetoself-interference aremorepronetohavecross-chainhiddenterminals.Thus,both intra-chainaswellascross-chaininteractions,ultimatelyprovide significantinsightintohowchainsinteract.

Chains or multi-hop paths are fundamental communication structures in Multi-Hop Wireless Networks (MHWNs). Understanding chain behavior is critical in order to build effective higher layer protocols. This paper examines the problem of how MAC level interactions influence chain behavior in a general MHWN where multiple chains coexist. We first classify chains based on the MAC interactions observed between its hops when there is no external traffic. Then we identify the interactions across two interfering chains for the most common categories of chains. We study the probability of occurrence, and estimate the effect of MAC interactions on the performance of the chains. We also show that different chains exhibit different transmission patterns; this is an effect that is necessary for accurately estimating chain performance. We observe that destructive interactions arise more frequently among two interfering chains than they do within a single chain. Moreover, chains that have hidden terminals due to self-interference are more prone to have cross-chain hidden terminals. Thus, both intra-chain as well as cross-chain interactions, ultimately provide significant insight into how chains interact.

Carrier Sense Multiple Access (CSMA) based MAC protocols induce several types of harmful interactions, such as hidden and exposed terminals, in wireless networks. Existing routing protocols do not consider the effect of these MAC interactions on route quality, leading to the selection of inefficient routes. We propose a MAC Interaction Aware Routing Metric (MIAR) that explicitly accounts for MAC interactions among the links forming a route. The protocol favors routes with links that have better interactions and avoids ones with detrimental interactions. We compare the performance of the proposed metric with an existing shortest-path routing protocol and show that our metric substantially improves the performance and efficiency of the network.

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