Wavelet Packets in Wideband Multiuser Communications

Abstract

REPORT DOCUMENTATION PAGEForm Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. 12b. DISTRIBUTION CODE ABSTRACT (Maximum 200 Words)Throughout the entire duration of this contract, the contractor has accomplished a number of tasks. First, we modeled communications channels using wavelet packets, for both time-invariant and time-varying channels. We then developed doubly orthogonal CDMA user spreading waveforms based on wavelet packets. We have also developed and evaluated a wavelet packet based multicarrier CDMA wireless communication system. In this system design a set of wavelet packets are used as the modulation waveforms in a multicarrier CDMA system. The need for cyclic prefix is eliminated in the system design due to the good orthogonality and time-frequency localization properties of the wavelet packets. Two new detection algorithms are developed to work in either time domain or wavelet packet domain to combat multiuser and inter symbol interferences. Compared with the existing DFT based multicarrier CDMA systems, better performance is achieved with the wavelet packet based system by utilizing the saved cyclic prefix overhead for error correction coding. Theoretical analyses as well as computer simulations are performed to support these claims.