Robust Adaptive Beamforming Algorithm in WPT-CDMA System
Ying Yang · Communications technology · 2009
The multi-carrier modulation with wavelet packet resolves the orthogonality damage in OFDM modulation caused by multi-path effect while decreases the SNR loss caused by cyclic prefix. Thus multi-carrier CDMA system using wavelet packet transformation (WPT-CDMA) has higher performance than OFDM-CDMA system. In the MIMO multi-user transmission condition, however, there are some flaws for constrained linear minimum square (CLMS) adaptive beamforming algorithm in WPT-CDMA system, e.g. the convergence is slower, the output performance worsens and the instability appears due to deviation from direction vector of received signal and limited samples. Therefore, a robust CLMS adaptive beamforming algorithm applied to WPT-CDMA system based on worst performance is proposed, thus to address these problems. Theoretical analysis and simulation results indicate that the system performance is significantly improved.