The SNR Performance of Cooperative Diversity in HF Skywave Communication Systems

High Frequency (HF) communication systems uses the ionosphere to reflect signals from the source (S) to the destination (D) on earth. Variation of the height of the earth’s ionosphere layer causes the received signal also to fluctuate and affects the signal-to-noise ratio (SNR) at the destination. To maintain the SNR remains good value at the destination, cooperative communication system can be a solution. In cooperative communication system, all sources cooperate and coordinate with the relay (R) to improve the quality of the signal at the destination. In this communication system, the destination receives two signals, each derived from source and from relay. This paper divides the simulation observation time into 3 categories, namely midnight to dawn (00:00 and 04:00), morning to noon (08:00 and 12:00) and afternoon to evening (16:00 and 20: 00). In all categories of midnight to dawn, morning to noon and afternoon to evening, cooperative communication systems with maximal ratio combining (S - R - D) provide greater diversity gain than non cooperative communication systems (S - R - D).