System architecture of an HF multi-station node controller

The evolution of automatic HF control has up to recently mainly been focused upon two factors, namely maximizing the time availability of a link and ease of handling the HF station. The solution has been to use automatic control and adaptive selection of radio parameter values (frequency etc.). Professional (and especially military) use of the HF medium has traditionally meant requiring a multitude of HF stations at each node (or communications site) to compensate for the relatively poor traffic throughput on each link. Furthermore, fixed HF links have been used, i.e. traffic to/from a certain other node is always passed via a certain HF station at the node in question. This paper addresses the next stage of development, being to focus on the radio nodes instead of individual stations at each node, i.e. the development of a node controller. The purpose of the node controller is to make the best use of the available radio resources at that node. The key features to be embedded in the node controller are described in the forthcoming sections. Thereafter a network simulation model is given which is used to show some examples of the impact a node controller has on the network traffic throughput capability