抄録
In real time communications on LAN such as FDDI utilizing the synchronous class of Timed Token Protocol (TTP), there exists a problem that the transmission delay time of synchronous data with Poisson arrivals at LAN nodes from upper layer largely increase in the range that the average load of synchronous data is close to the synchronous bandwidth. It is caused by the fact that TTP has not a function to process excess data that arrive at LAN nodes earlier than the timing determined with pre-assigned synchronous bandwidth
In this paper, in order to solve the problem, we propose another data transfer protocol “Advanced Timed Token Protocol (ATTP)” of which data transfer mechanism is modified from TTP and improves the transmission delay time of synchronous data including above mentioned excess data by rotating token more quickly on LAN than TTP. Furthermore we show the effectiveness of the protocol by simulations on the model of time critical communication for manufacturing control system.
