Multi-Carrier Communication System Based On Wavelet Packet Division Multiplexing

With the maturity of 3G communication technology and already into commercial operation, the development of next generation wireless communication systems have been put on the agenda. Advanced modulation combined with multi-carrier communication, with its high spectral efficiency, good anti-fading ability, is considered as the key technology in next-generation wireless communication system. Wavelet packet division multiplexing does not only have good anti-ISI, ICI ability, but also has better ability of adapting to the channel than OFDM technology. However, difficulties in high peak to average power ratio, sub-carrier bases selection and optimal basis selection has restricted the further development and application of wavelet packet division multiplexing. This thesis will address the above issues, and process deep and meticulous research.This thesis first summarized and described the current statue and future prospects of multi-carrier modulation and wavelet packet division multiplexing, introduces the time-frequency analysis and wavelet packet theory. Based on that, this thesis analysed the anti-interference performance. of different sub-carrier bases in multi-path fading channel, and given the selection principle of sub-carrier bases in frequency dispersion channel, wavelet packet function is proposed to replace the traditional sine-base used in OFDM technology for transmission, using its self and cross orthogonality to obtain better performance against noise and interference. Experimental results demonstrate the feasibility and effectiveness of this method.In the following part, analyzed the composition and selection principle of wavelet packet basis, and a novel search algorithm for wavelet packet basis was proposed. This algorithm decomposes the whole wavelet packet library from top to bottom by its binary branch, use ICI and ISI integrated power and Peak to Average Power Ratio (PAPR) for competitive decision to select optimal basis. Finally the algorithm was tested in 4-path Rayleigh fading channel. Simulation results indicated that: the operation speed of the algorithm is better than two existing algorithms, and the output of the optimal basis structure gain about 20% performance increase than full decomposed structure.Final chapter is the summary of the main work and future trend of the wavelet packet division multiplexing and multi-carrier communication technology.