Optimal synchronous capacity allocation for hard real-time communications with the timed token protocol

The authors study the problem of transmitting synchronous messages before their deadlines in communication networks where the timed token medium access control protocol is employed. Synchronous capacity, defined as the maximum time for which a node can transmit its synchronous message every time it receives the token, is a key parameter in the control of synchronous message transmission. To ensure the transmission of synchronous messages before their deadlines, synchronous capacities must be property allocated to individual nodes. The authors develop and analyze an optimal synchronous capacity allocation scheme. An optimal scheme can allocate the synchronous capacities in such a way that the synchronous message deadlines are guaranteed if there exists any allocation scheme that can do so. The optimality of the allocation scheme proposed here is formally proved, and the bounds for its worst case achievable utilization are derived