Research On Anti-multipath Fading Techniques In Burst Communication System

The thesis comes from a communication project between air and ground. For the sake of the Ricean channel and the particularity way of communication, something must be done to reject multipath propagation although complicated equalization is misfit. Current burst communication system which adopts MSK or QPSK modulation also exists the problem that is weak in rejecting multipath propagation. In order to solve the problem, this thesis consider it from modulation and channel coding alliance.Complementary Code Keying(CCK) is a way of Code Modulation. By lots of simulation work, it seems that CCK has a good ability to overcome multipath propagation. However, strong multipath interference maybe deteriorate the performance.A soft CCK demodulation is proposed in this thesis to take the lower reliability step codewords as erasure symbols by measuring the correlation and dissociate the erasure symbols into different codewords by interleaving. Meanwhile, channel estimation and equalization is adopted to alleviate the interference of strong multipath. The simulation result show that the proposed methods can give about 2dB improvements at high SNR and equalization can give about 1.5dB.By simulation results, it validates the effectiveness of the scheme and can reject more multipath interference.