A feedback adaptive space-time constant modulus algorithm in DS-CDMA multiuser detection

The constant modulus property of communication signals, such as FM and phase-modulated signals, are often used in blind separation of multiple users. Because there are no training sequences needed, the system transmission efficiency is increased. When extended to the space-time domain, the new schemes have potentially greater performance than conventional ones. In this paper a feedback adaptive space-time constant modulus algorithm (FAST-CMA) is proposed for DS-CDMA multiuser detection. First the uplink channel model is built with receiving K synchronous communication signals that are transmitted through a MIMO-FIR channel. Based on this channel model, we compare and analyze the FAST-CMA with cascade-type constant modulus algorithm (CT-CMA) and space-time type constant modulus algorithm (ST-CMA). The FAST-CMA can combat both ISI and MAI without stringent power control and training sequence, and it is preferable to CT-CMA and approximately has the same performance as the ST-CMA. It has faster convergence rate, and less computational complexity than ST-CMA. Numerical simulations can illustrate the effectiveness of this algorithm