Performance characteristics of high data rate HF waveforms

The ability to use high order modulation schemes combined with the improvements in coding and equalisation have enabled the development of waveforms capable of providing data rates of 9600 bps (and above) in a standard 3 kHz HF radio channel. There is now an urgent need to standardise such waveforms in NATO to provide interoperable high data rate HF communications. However there are many possible combinations of modulation and coding that could be used. In addition, the performance of any waveform will be influenced by the choice of preamble and training sequences to assist in channel equalisation. While the general principles for the design of suitable preambles or training sequences are now well understood the exact choice of parameters remains a complex issue and the final choice will affect overall performance. This paper gives a description of the evaluation process being used within NATO to select between three alternative HF waveforms designed to provide HF communications at data rates between 2400 and 9600 bps. These waveforms have been proposed for standardisation under a NATO STANAG. The paper also presents some preliminary results of the performance that will be achievable with the new high speed waveform.