Integrated protocols for guaranteeing time-critical communication in CSMA environments

Two protocols for carrier-sense-multiple-access (CSMA) transmission of time-critical messages are proposed. The basic idea of the protocols is to integrate some controlled access elements into the contention-based CSMA protocol. The proposed protocols are called the sparse integrated protocol and the periodic integrated protocol. The first protocol can be used in distributed systems in which time-critical messages appear occasionally. The latter can be used in distributed systems in which time-critical messages appear periodically. The operation mode of the original contention-based protocol is enhanced with an appropriate explicit reservation scheme to guarantee the successful transmission of time-critical messages. As a consequence the considered protocols guarantee that all time-critical messages meet their deadlines and operate nearly as efficiently as a contention-based protocol