Adaptive Frequency Hopping Technology Research

Adaptive frequency-hopping(FH, AFH) system can perform adaptive channel estimation, and adjusts modulation, power control and frequency selection adaptively in accordance with channel conditions, thereby greatly enhances the system capabilities of anti-fading, anti-jamming and anti-intercepted. It is of decisive significance and this dissertation has done lots of researches on this subject.First, this dissertation briefly introduces the basic characteristics of short-wave channel and short-wave communications, as well as the development course of FH communications. Then the development of AFH commu-nication and current research status are given, which set up the background for our researches. The dissertation achievements and structures are listed at the end of chapter one. Chapter 2 briefly introduces some AFH relevant techniques, including the basic principles of FH communications, practical FH communication systems and baisc AFH techniques, which will pave a way for the following research.Chapter 3 formulates the researches and achievements on adaptive channel estimation algorithms. The dissertation detailedly expatiates the SNR estimation algorithm based on the auto-correlation matrix of observation vector, discusses and compares the AIC and MDL algorithms, analyzes the potential problem and corresponding amend for the latter one, furthermore, the situation of more common auto-correlation matrix is discussed. The dissertation proposes an estimation algorithm for the channel fading, proves its simplicity and efficiency by some simulation results .Chapter 4 formulates the researches and achievements on adaptive control. The dissertation proposes a joint adaptive modulation and power control algorithm, analyzes its principles and gives the full implementation, points out some attentions on the relevant matters, and the simplified solutions are discussed for comparison to the conventional adaptive modulation and power control. The dissertation also proposes optimized algorithms on the aspects of adaptive frequency selection, band selection and sub-band selection. Simulation results show that the algorithms proposed in this dissertation are highly effective.Finally, the dissertation summarizes the whole work and gives some directions for the further research.