The Complex Spherical Decoding Algorithm Research in WPT-CDMA System

Maximum likelihood (ML) detection algorithm is the best method for multi-user detection, but it has high computational complexity. This paper presents a view of this issue to its rapid and effective method, that is, complex spherical decoding algorithm. This algorithm not only maintains good performance of the ML detection, but also has a low computational complexity. On the other hand, the multi-carrier modulation with wavelet packet doesn´t give rise to high side lode caused by OFDM technique, so that it avoids the loss of orthogonality duing to multi-path effect which leads to severe inter-channel interference. This modulation scheme also avoids the loss of SNR on account of cyclic prefix´s application. We combine these two techniques to propose the complex spherical decoding algorithm in MC-CDMA modulated by wavelet packet (WPT-CDMA) system, the performance of multi-user detection has great improved from the results of simulation.