Modeling Automatic Link Establishment in HF networks

Most High Frequency (HF) communications systems deployed on the field today implement ALE (Automatic Link Establishment) techniques in order to help the end-user automatically set up a link with good properties. Two generations (so called 2G and 3G ALE) have been standardized since the 90s, and are today being revisited due to the emergence of wideband HF waveforms. In this paper, we model ALE protocols using an abstraction model based on Markov chains. Our model captures faster and more easily than simulations the main characteristics of the ALE processes and the interactions between their numerous parameters. In that sense, this model constitutes a useful tool to help design and benchmark future ALE strategies. In order to validate the model, classical ALE simulations have also been carried out, that show the high similarity obtained with the model. We also show how to exploit the model to give insights on the limitations of current 2G ALE, for instance on the handshake method and on the impact of frequency selection strategy on the ALE duration.