Cognitive Hf Communication System With Adaptive Complementary Codes

High frequency (HF) band covers frequencies between 3-30 MHz. With wavelengths of 10-100 m, HF band enables communications over a very long distances though a skywave propagation. As HF band has several benefits like versatility and large coverage area, it suffers phenomena like rapidly changing environment and strong interference. The cognitive radio concept which adapts to the changes in the environment offers tools to solve those problems. In this paper, HF band challenges caused by ionospheric break and interference are solved using databases and complementary codes that adapt to the characteristics of different data transmission requirements. The goal is to optimize used frequencies based on the data transmission needs.