Channel Access over Path Segments for Ultra Low Latency MANETs

While the capacity of Mobile Ad Hoc Networks (MANETs) has received considerable attention, the issue of end-to-end latency has been largely ignored. As military MANETs get larger and denser with an increasing number of end-to-end hops, the latency and jitter experienced by packets will be prohibitively high for existing and emerging real-time applications. We present and study a novel mechanism called CAPS (Channel Access over Path Segments) for reducing end-to-end latency. The key idea behind CAPS is to reserve the floor multiple hops (a path segment) at a time. This is accomplished by using multi-hop RTS and CTS frames that acquire the access rights for an entire segment toward the destination, with virtual carrier sense acting on a path basis. Our architecture also includes a cut-through physical layer that pipelines a bit stream through the receive and transmit chains. We present a numerical analysis of the relative performance gain from our ideas, complemented by a simulation-based analysis. Our study shows that, depending upon the parameters used, a 3x to 8x reduction in latency over current systems is possible.