VDL Mode 3 subnet simulation models in OPNET

The Very High Frequency (VHF) Digital Link (VDL) Mode 3 is based on a Time Division Multiple Access (TDMA) media access control (MAC) protocol. This MAC protocol incorporates priority queuing, slotted ALOHA, and polling by the ground station to handle channel contention and to achieve the speedy delivery of time critical ATC messages. This paper provides an overview of the VDL Mode 3 subnet simulation models in Optimized Network Engineering Tools (OPNET). Four different subnet models are available for the simulation of different system configurations, namely, 2V2D, 3V1D, 4D, and 3T. The usefulness of these simulation models is demonstrated by their capability in simulating a wide range of scenarios and protocol alternatives in dealing with various configurations, load factors, and protocol parameter settings.