WiDom: A Dominance Protocol for Wireless Medium Access

Wireless networks play an increasingly important role in application areas such as factory-floor automation, process control, and automotive electronics. In this paper, we address the problem of sharing a wireless channel among a set of sporadic message streams where a message stream issues transmission requests with real-time deadlines. For this problem, we propose a collision-free wireless medium access control (MAC) protocol, which implements static-priority scheduling and supports a large number of priority levels. The MAC protocol allows multiple masters and is fully distributed; it is an adaptation to a wireless channel of the dominance protocol used in the CAN bus, a proven communication technology for various industrial applications. However, unlike that protocol, our protocol does not require a node having the ability to receive an incoming bit from the channel while transmitting to the channel. The evaluation of the protocol with real embedded computing platforms is presented to show that the proposed protocol is in fact collision-free and prioritized. We measure the response times of our implementation and find that the response-time analysis developed for the protocol indeed offers an upper bound on the response times