Enhancing channel utilization and performance of Stanag 5066

NATO Standardization Agreement 5066 (STANAG 5066, or S5066) defines a Data Link Protocol Profile for exchanging digital information over HF radio. As more S5066 deployments are made, problems arise in two important areas: channel contention among multiple nodes on shared frequency, and poor ARQ performance on payloads under 5000 bytes. These two areas impact the ability of S5066 networks to efficiently transfer many types of traffic, most especially those seen over IP networks. This paper takes a closer look at these areas, examining how the current S5066 standard addresses them, and examines the measured performance seen on a five node network. The tests involve focusing on the issue of collision avoidance, and what steps can be taken to reduce the likelihood. In addition, an improved channel access scheme is presented, that demonstrates measurable increases in channel utilization by the reduction of on-air collisions.