Adaptive Coding and Modulation Techniques for HF Communication: Performance of different adaption techniques implemented with the HDL+ protocol

Abstract

The main goal of this thesis is to present two good alternatives for the HDL+ protocol proposed for ratification in STANAG 4538, as this partially is restricted by a patent claims. The HDL+ protocol is used as a starting point, and in order to accommodate for the patented parts, the adaptive process is altered, and the code combining process is removed for the highest rate. For simplifying the comparison between the performance of the proposed protocols, and the HDL+, both proposed protocols is simulated in a MATLAB environment, over the same channels as Harris has presented the throughput capabilities of the HDL+. These channels include the AWGN, single tap channel with flat fading, the ITU-MLD channel, and the ITU-MLD channel with Long- and Intermediate- Time SNR variations. By analyzing the results, it is clear that the current implementation of the proposed protocols does not achieve as high throughput as the HDL+, but there are indications that there is potential for better results if further development is performed.