Voice priority net access delay (V-NAD) algorithm in MIL-STD-188-220B

The presence of multiple stations on a single SINCGARS net requires a method for controlling the net access opportunities for each station. In order to minimize conflicts, various net access delay (NAD) schemes have been proposed to access CSMA timing slots randomly for channel requests. The load factor NAD (L-NAD) algorithm was implemented and demonstrated successfully in ITT´s Internet controller (INC) (with the MIL-STD-220-188B protocol during US Army´s Task Force XXI Advanced Warfighting Experiment. Many valuable lessons were learned from this experiment; particularly, about the efficiency issues when voice is mixed with data (0%, 30% and 60% voice load). The voice priority NAD (V-NAD) algorithm proposed, is intended to enhance the L-NAD algorithm to achieve better net performance (including reduction of net fragmentation). In V-NAD, a voice monitoring mechanism triggers a stepwise increase of the NAD when voice is detected in a net. This increase (or “attack”) is continued up to a maximum value if the channel is busy by voice consecutively, upon the scheduler timer expiration. If the channel is not busy by voice, the voice monitoring mechanism starts to decrease (or decay) step-wise down to a minimum value. This paper presents performance results of the V-NAD over the L-NAD algorithm for the TIDB Phase 2 network associated with the IOT&E. These results were obtained using the fully integrated ITT TIDB Phase 2 OPNET^TM model. This model is an upgrade of the earlier TIDB LUT model incorporating the networking features being developed for the IOT&E. The study assumes a fully connected net and a benign electromagnetic environment