Performance Analysis of Multi-Rate Capable Random Access Mac Protocols in Wireless Multi-Hop Networks

In this paper, we study an ad hoc wireless network system in which multiple access wireless channels are shared in accordance with a random access (ALOHA type) MAC protocol. We assume that a modulation/coding scheme (MCS) can be selected from a list of available such structures, each of which is associated with a transmission data rate and an acceptable SINR level that yields a prescribed BER value. The use of such different MCSs impacts the achievable value of the system´s spatial reuse factor level and of the realized end-to-end lengths of flow paths. Consequently, as the traffic loading level increases, the use of such different schemes yields different throughput capacity levels. We present mathematical models that enable the selection of the MCS that yields the highest level of throughput performance. For the multi-hop network system, we demonstrate that the link range and the employed MCS can be jointly selected to yield the highest throughput capacity level. We show that for the system under consideration it is generally preferable for a node to use a high data rate MCS while jointly selecting its neighbours from a usually reasonably short range level