Medium Access Control for Wireless Networks with Diverse Time and Safety Real-Time Requirements

The communication in-between embedded systems present in cars and planes, requires real-time networks. Up to now, fieldbus technologies like PROFIBUS and CAN have covered the demand for predictable communications in embedded systems. However, these fieldbuses do not suit some of the emerging application domains, that need more flexibility, support for dynamic traffic flows, different traffic classes, high throughput, and the inclusion of wireless capabilities. To this end, we propose several different medium access control (MAC) schemes with support for traffic with diverse time and safety requirements. We have calculated the worst case channel access delay for each proposal, and also simulated them in OMNeT++ to analyse and compare their performance in terms of average access delay and packet collisions as a function of different protocol settings and traffic patterns e.g., the channel load, data traffic emerging from one sender only versus evenly distributed between all senders. Our results indicate that the more that is known about the data traffic, the better performance can be achieved by selecting an appropriate MAC protocol. Conversely, when nothing is known, one MAC protocol emerges as the best trade-off.