Performance of the combined free/demand assignment multiple access protocol via underwater networks

This paper considers the use of Combined Free/Demand Assignment Multiple Access (CFDAMA) for Underwater Acoustic Networks (UANs). The long propagation delay places severe constraints on the trade-off between end-to-end delay and the achievable channel utilisation. Free assignment is shown to offer close to the theoretical minimum end-to-end delay at low channel loads. Demand assignment is shown to have a much greater tolerance to increasing channel load over virtually the entire channel utilisation range, but with longer delay. CFDAMA is shown to exhibit significantly enhanced performance with respect to minimising end-to-end delay and maximising channel utilisation.