Simulation studies of MAC algorithms for combat net radio

The studies focus on the simulation of two media access control (MAC) algorithms in the MIL-STD-188-220A datalink layer protocol. The studies compared and optimized the MAC algorithms for Type 2 service. The current simulation model is an extension of a model that had been verified and validated against our communication lab data. We have used this model to examine the performance of the deterministic adaptable priority network access delay (DAP-NAD) algorithm for fire support message sets and for non-threaded, arbitrary size and destination, single message (called generic) loading of the networks. We have shown, for DAP-NAD, how the network performance degrades as the number of subscribers on the network increases. We have also shown how the performance of the network is heavily dependent on the assignment of the transmit opportunity sequence (called subscriber numbers.) We have developed an algorithm for this assignment that improves the network performance. We have also used the simulation model to compare the performance of the radio embedded network access delay (RE-NAD) and the DAP-NAD algorithms for both the fire mission sets and for generic message sets. We have shown for various scenarios where DAP-NAD is the preferred algorithm and also a situation where DAP-NAD is a very poor choice. It appears, in general, that DAP-NAD performs particularly well on stable networks with a moderate number of subscribers with the appropriate assignment of subscriber numbers. We note that most of the results are obtained from heavily loaded networks. Response time on lightly loaded networks is of interest but is not as important for our applications.