Evaluation of Wireless Soft Real-Time Protocols

Communication between current military real-time systems and future interconnection of general purpose, embedded real-time systems will often require wireless communications. However, there has been little work undertaken to offer support for real-time applications on wireless networks. We present and evaluate three protocols; variations of two published protocols by Paterakis and Gallager as well as our new one, the Sliding Partition (SP) collision resolution algorithm (CRA). In a real-time setting, the modified Gallager CRA consistently performs worst of the three we consider. We observe that when the deadline range is small, the Sliding Partition CRA performs best. When the deadline range is large, however, the Paterakis CRA performs slightly better than the SP CRA. Both analytic and simulation results are obtained to study the maximum input traffic rates that can be sustained for various laxities, delay bounds, and message loss rates.