Analysis Of WPDM Systems Performance

Wavelet packet multicarrier modulation system(WPDM), is a new multi-carrier modulation technique which produced by a wavelet packet transform applied to a multi-carrier modulation system. The wavelet packet function, which is orthogonal on both time and frequency domain, combined with multi-carrier modulation technology, which has the advantage of resisting multipath fading, allows WPDM system having high frequency utilization efficiency and good resistance to both fading and interference, as well as the feature of easy implementing of multi-rate transmissions. Hence compared to traditional OFDM system, WPDM system has better performance on those parts.The main purpose of this thesis is to choose the best wavelet basis for WPDM, after analyzing the futures of different wavelet bases we chose the most suitable wavelet basis for our WPDM system based on the optimal wavelet basis choosing principle and the simulation results. Also combined with the application of wavelet analysis on de-noising, we simulated the channel estimation based on wavelet de-nosing. With the simulation results, we analyzed the influences of choosing threshold and wavelet basis on wavelet de-noising and compared wavelet de-noising method with the common channel estimation methods, which showed the advantages of wavelet de-noising. In the end we compared WPDM system and OFDM system of their performances based on the channel modeling and simulation through MATLAB.Through theoretical analysis and experimental results, considering various factors, Db4 wavelet set can significantly improve the performance of WPDM system, which can implement through using the equivalent filter algorithm. For the channel estimation algorithm, the estimation algorithm based on wavelet de-noising has been verified can not only reduce the computation amount, but also greatly improve the performance of the system, which is an effective channel estimation algorithm.