Real-Time Communication in IEEE 802.11 Mobile Ad hoc Networks A Feasibility Study

Achieving predictable communication latency in an ad hoc IEEE 802.11 wireless local area network necessitates an approach that overcomes the impact of the underlying non-deterministic contention-based medium access control (MAC) protocol. In this paper, we assess the feasibility of using a Time Division Multiple Access (TDMA) layer above the IEEE 802.11 MAC protocol in order to achieve such predictable communication latency. We present the design and implementation of this TDMA layer and describe the influence of both the characteristics of the IEEE 802.11 MAC protocol and of the dynamics of an ad hoc network on its design. We show that our approach can yield the predictability and stability required to support real-time communication in a real ad hoc environment, typified by dynamic host mobility and varied offered load, subject to identified constraints.