Rearch On The Wideband HF Communication Techniques Based On OFDM

The High-Frequency communication is undoubtedly the hot topic of the research on remote military telecommunication. With the growth in demand for data services, high-speed HF communication is one of the future development trends of military communication. Because of the excellence performance and high spectral efficiency, the usage of Orthogonal Frequency Division Multiplexing (OFDM) in wideband HF communication have received extensive attention from worldwide scholars, and hence become the main modulation schemes. A significant subject for research is how to enhance the ability of receiver to combat interference under poor HF channel.This thesis is aims at the crucial techniques for OFDM system used in wideband HF communication. From the channel characteristics of HF transmission, we analyze the poor HF channel and possible interference problem that we have to face. We put forward concrete solutions for the crucial techniques for OFDM under the poor wideband HF channel, like synchronization, channel estimation and equalization. Also, we give the simulation results and analysis. This thesis is organized as follows:Chapter one gives a brief overview of the development of HF communication and OFDM technology, followed by the main objective of this thesis.Chapter two presents the wideband HF channel model and the basic principles of OFDM, followed by the crucial techniques for OFDM. Those are synchronization and equalization.Chapter three addresses the problem of synchronization under wideband HF channel by comparing the typical time-domain and frequency-domain algorithm.Chapter four addresses the problem of channel estimation and equalization. Except for the introduction of traditional algorithm for channel estimation and equalization, we induce a new Turbo-equalization for OFDM with excellent performance.