A Theoretical Evaluation of the G-TOR Hybrid ARQ Protocol

The recently-introduced G-TOR protocol for HF data communications employs several features which maintain the throughput of this system in the presence of noise and interference. In this paper we take a closer look at the most important of these features the hybrid AR& protocol in order to provide G-TOR users with a better understanding of the technical details of the protocol and an appreciation of the role of the Golay forward error correcting code in improving the overall system performance. We will demonstrate the advantages of using a hybrid ARQ protocol by presenting a theoretical evaluation of the throughput of the G-TOR hybrid ARQ protocol in the presence of Gaussian noise. Graphs of throughput versus channel bit error rate will show that the combined use of error detection and Golay forward error correction is a powefil approach to extending the throughput of a conventional stop-and-wait ARQ system on the HF bands.