A Framework for Modeling Operating System Mechanisms in the Simulation of Network Protocols for Real-Time Distributed Systems

In this paper we present a software tool for the simulation of distributed real-time embedded systems. Our tool is based on the popular NS-2 package for simulating the networking aspects, and on the RTSim package for the realtime operating system aspects. By reusing much of the existing code, our simulator covers a very wide range of network protocols and real-time mechanisms. After describing the architecture of our tool, we tested it in a simple wireless sensor networks scenario, and we measured the latency in transmitting and receiving messages due to the concurrent activities in the nodes. These effects have been tested against two node scheduling policies, and under different load conditions in the CPU of the nodes.