Sample Synchronization And Blind Channel Estimation For Multi-Carrier Modulation Based On Wavelet Packet Transform

Wavelet packet division multiplexing is a technique combing wavelet and wavelet packet theory of mathematics with multi-carrier modulation technique of communication. It provides higher frequency efficiency, better performance resisting fading and interference and more flexibility to implement multirate transmission.The purpose of this paper is to discuss the sample synchronization and channel estimation techniques for WPDM system. First, based on multi-carrier modulation techniques, it discusses the fundamentals and performances of multi_carrier modulation technique, expounds on OFDM and WPDM in detail; analyses the necessity of sample synchronization and dissertates the feed-forward decision-directed(DD) maximum likelihood (ML) sample timing method. After introducing the characteristics, types, statistic and theoretical models of wireless channels, it points out the importance of channel estimation for the mobile communication in future, and discusses blind channel estimation technique based on SVD (Singular Value Decomposition)mostly. For each part, MATLAB and SIMULINK simulation are done to validate its performance in WPDM system.The analyses of theory and experimental results indicate that feed-forward DD ML and SVD based channel estimation can reduce intersymbol interference effectively, decrease error rate and increase QoS of communication greatly.