RADcast: Enabling Reliability Guarantees for Content Dissemination in Ad Hoc Networks

This paper deals with the problem of reliable and fast broadcast of mission-critical data with rich content over ad hoc networks. Existing approaches to dissemination reliability often assume network size knowledge, or that receivers know about the dissemination in advance. Without making similar assumptions, we propose a distinct approach which accommodates the varying reliability needs of applications. We develop the RADcast (reliable application data broadcast) protocol as an integration of two components: (a) Peddler, which ensures that receivers obtain the dissemination metadata, and (b) Pryer, which delivers the actual data to dissemination-aware receivers. We indicate how reliability guarantees/performance tradeoffs can be achieved by a careful instantiation of Peddler and Pryer. We implement RADcast on mobile devices inside a middleware and determine its feasibility. Furthermore, through extensive simulations, we show that RADcast achieves desired reliability in all cases, and performs consistently under varying network conditions and device mobilities. As compared to existing approaches, RADcast either incurs significantly lower latency/message overhead, or reduces latency by 50% with a tradeoff in message overhead.