On a Characteristic of Data Transmission with Three or More Priority Levels in Bus Network

This paper presents a characteristic of data transmission in bus network in which each datum has a priority and the number of priority levels are three or more. In this bus network, each station is connected to a bus through a switching-hub which establishes a link from a sending station to a receiving station. When the receiving station is sending data or receiving data, the link cannot be established and the sending station has to wait a little waiting time (stand-by time). Then, by defining the link probability as a constant, the bus network is analyzed. Taking note of one of the sending stations with r(r≥3) sending buffers for data with priority, in steady state, a balance equation of the probabilities of the number of waiting data at the ready time of sending is expressed. From the equation, for each priority, probabilities of the number of waiting data, mean of the number of waiting data in the sending buffer and mean waiting time which is the time from the arrival time of a datum at the sending buffer to the beginning time of sending the datum are derived. The calculated values of mean waiting time are illustrated and mean waiting times with priority processing are compared with mean waiting time without priority processing. As a result, the influence of the link probability on data transmission with priority processing is clarified.