On Adaptive HF Networks in Benign and Stressed Environments

In order to optimize performance, an HF system must have increased capabilities from conventional systems, including the ability to select an operating frequency adaptively and automatically, the use of sophisticated waveforms for operating in fading channels and the use of adaptive protocols in the areas of message relaying, message routing and allocation of resources. This paper investigates the message connectivity and time delay characteristics of various adaptive network protocols intended to make best use of existing resources at the nodes. Adaptive HF network models, incorporating IONCAP propagation prediction results for the network links are described, and connectivity and message delay performance based on these models is shown. Performance as a function of network architecture, routing protocols and sounding protocols is presented. Network performance in an ECM environment is discussed. Results are shown for adaptive vs. nonadaptive operation, as well as the effect of using various network topologies as a jamming countermeasure.