Low complexity LMS based adaptive iterative receiver for CDMA systems

An adaptive iterative frequency domain receiver for a Layered Space-Time Coded CDMA (LSTC-CDMA) system has been proposed in this paper. The proposed receiver, based on a joint adaptive iterative detection and decoding algorithm, adaptively cancels Co-Channel Interference (CCI) and mitigates Multiple Access Interference (MAI), and also has a significant reduction in computation complexity with the same performance compared to a time domain receiver. The Least Means Square (LMS) algorithm is used for both feed-forward filter and feedback filter in the adaptive detection. A Partially Filtered Gradient LMS (PFGLMS) algorithm is also proposed to improve the convergence speed of the adaptive detector. The performance results show that the proposed adaptive receiver can approach the interference-free single user performance for a certain range of the signal to noise ratio (SNR).