Performance evaluation of the SHINPADS protocol by extended M-type Petri nets

The author modeled the simplified SHINPADS (SHipboard INtegrated Processing and Display System) protocol using extended M-type Petri nets. The simplification consists of the cancellation of priorities. The extended nets not only use ordinary arcs but also include inhibit arcs, which make them more general, and gate arcs, which reduce the number of places and make them a more natural modeling tool. They also accommodate unbounded places. The author developed a program to map those Petri nets into Markov chains and calculate the performance of the protocol for different traffic loads and protocol parameters. For the Markovian property, all transitions must have negative exponential firing times and, correspondingly, control and data messages must have negative exponential length as well as time between them. Under these restrictions the results obtained are exact and general and can be used in the design of the SHINPADS protocol. The throughput for data and control channels vs. offered traffic for different parameters shows the stability of the protocol under heavy load