Low complexity adaptive iterative receiver for layered space-time coding CDMA systems

It is well known that an adaptive frequency domain receiver can dramatically reduce the detection computation complexity of a communication system compared to standard time domain receiver. In this paper, we propose a new low complexity frequency domain adaptive and iterative receiver for a layered space-time coded CDMA (LSTC-CDMA) system with no knowledge of channel state information (CSI), spreading sequences, and the fading coefficients, except a training sequence for each user. The proposed low complexity receiver consists of a normalized LMS feed forward filter and a feedback iterative parallel interference canceller in frequency domain. The proposed frequency domain receiver has a significant reduction in computation complexity and achieves the same performance compared to a time domain receiver. Our simulation results exhibit that the proposed adaptive iterative receiver can also approach the interference-free single user performance for a certain range of the signal to noise ratio (SNR)