Towards analytic modeling for CSMA/CA based MAC protocol in wireless multi-hop networks - A simulation study

This paper reports on research into the relevance and prevalence of different events and conditions occurring at the Medium Access Control (MAC) layer in a multi-hop wireless network scenario. The purpose of this research is to determine which events and conditions are essential to an analytic model, and which can be ignored for the sake of simplicity, because simplicity and accuracy are generally competing factors in the design of a model but complimentary factors in the usefulness of a model. The research focuses on one important class of MAC protocols, Carrier Sense Multiple Access schemes with Collision Avoidance (CSMA/CA) as implemented in IEEE 802.11 type networks. The behavior of these protocols in the multi-hop scenario is significantly different from their behavior in the more commonly studied single-hop scenario. The research identifies what events are possible in the multi-hop scenario and uses a detailed simulator to evaluate their frequency and effect in different topologies and with different protocol parameters. Unfairness, different types of collisions, throughput, and other factors are considered. The observations are used to formulate directions for future analytic modeling approaches.