Research On Channel Estimation And Equalization In Multipath Fading Channels

Multipath spread and varying of channel are the two main issues need to be solved in wireless communication systems. A proper channel estimation and equalization method in some specific multipath fading channel will play an important role in the improvement of overall performance. This paper is committed to solve practical problems encountered in engineering: channel estimation and equalization for high-speed multi-carrier short-wave systems and a broadband single-carrier aviation communication system. HF channel is a typical frequency selective fast fading channel. Multipath and Doppler spread have huge influence in it. Traditional channel estimation methods of OFDM systems are not adopt to the bad conditions in HF channel. The power of multipath in the high-speed single-carrier aviation communication system are great, and it caused serious inter-symbol interference. More importantly, the number of symbols corresponding to the multipath delay is also large, making complexity of existing channel estimation and equalization methods increase drastically. That is to say, traditional methods can’t meet the engineering needs in these conditions.This paper focus on channel estimation and equalization in multipath fading channel, and designed proper methods for shortwave OFDM systems and the high-speed single-carrier aviation communication system. The work in this paper has important theoretical significance and application value.Main work and innovations of this paper are as follows:1, Improved and integrated the existing OFDM system channel estimation methods, and proposed a joint channel estimation method for shortwave OFDM system. This method combines the features of several existing channel estimation, overcomes the shortcomings of them, and is applied in real systems eventually.2, Proposed a single-carrier channel estimation method. It takes use of PN sequence, has low complexity and low MSE, and could be used to resolve the long multipath delay problem.3, Proposed several equalization methods based on channel estimation, and resolved the problem encountered in high-speed single-carrier aviation communication system. These work play an important role in the application of shortwave OFDM systems and high-speed aviation data link, and also have reference value for other multi-carrier/single-carrier systems’channel estimation and equalization design.