REAL-TIME COMMUNICATION IN MULTIHOP NETWORKS

Communication in real-time systems has to be predictable, because unpr edictable delays in the delivery of messages can adversely affect the execution of tasks dependent on these messages. In this paper, we deve lop a scheme for providing predictable interprocess communication in r eal-time systems with (partially connected) point-to-point interconnec tion networks, which provides guarantees on the maximum delivery time for messages. This scheme is based on the concept of a realtime channe l, a unidirectional connection between source and destination. A real- time channel has parameters that describe the performance requirements of the source-destination communication, e.g., from a sensor station to a control site. Once such a channel is established, the communicati ons subsystem guarantees that these performance requirements will be m et. In this paper, we concentrate on methods to compute guarantees for the delivery time of messages belonging to real-time channels. We als o address problems associated with allocating buffers for these messag es and develop a scheme that preserves delivery time guarantees.