The design and analysis of the AFATDS communication networks using simulation

This paper presents a brief overview of the simulation of communication systems including the role of simulation in their design and analysis. It focuses on the communication performance modeling of the Advanced Field Artillery Tactical Data System (AFATDS) communications system. Particular attention is paid to the verification and validation of the simulation model. AFATDS is a multi-service automated command and control system for the fire support operations. AFATDS provides the capabilities to process, analyze, and exchange combat information within the AFATDS architecture and with other Army battlefield artillery systems. AFATDS is a system of mobile, dispersed, multi-functional nodes providing automated planning and execution capabilities to support operational facilities (OPFAC). Our modeling effort is concerned with the communication protocol stack for the AFATDS communication network but is primarily focused at the data link control and network access control layers. We implemented (using the simulation modeling tool OPNET) the variable message format (VMF) protocol (it has many areas of commonality with MIL-STD-188-220 A). We examined the effect various system timers have on the system performance. We studied the effect the processor polling frequency of the modem has on the system throughput and on the average time to complete processing of mission threads. The media access timers, the retransmission timer of the data link control layer, and the segment size limits are also studied to optimize system performance.