Version selection schemes for hard real-time communications in multiaccess networks are studied. Two classes of version selection schemes are proposed: those that are based on message time constraints and those that are based on the network traffic. The authors discuss the design and implementation of both classes of version selection schemes used in conjunction with a window-based media access protocol. Integrated version selection schemes that combine both the timing- and the traffic-based approaches are discussed. The simulation results show that as the network load increases, the version selection schemes are effective at reducing the message loss by trading off the proportion of long version messages sent.
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