ANear-Optimum Multiuser Receiver for STBCMC-CDMASystems Based onMinimumConditional BER Criterion andGenetic Algorithm-Assisted Channel Estimation

The implementation of efficient baseband receivers characterized by affordable computational load is a crucial point in the development of transmission systems exploiting diversity in different domains. This would be a crucial point in the future development of 4G systems where space, time and frequency diversity will be combined together in order to increase system throughput. In this framework, a linear multi-user detector for MC-CDMA systems with Alamouti’s Space-Time Block Coding (STBC), which is inspired by the concept of Minimum Conditional Bit-Error-Rate (MCBER), is proposed. The MCBER combiner has been implemented in adaptive way by using Least-Mean-Square (LMS) optimization. The estimation of Channel State Information (CSI), necessary to make practically feasible the MCBER detection, is aided by a Genetic Algorithm (GA). The obtained receiver scheme is near-optimal, as both LMS-based MCBER and GA-assisted channel estimation perform closely to optimum in fulfilling their respective tasks. Simulation results evidenced that the proposed receiver always outperforms state-of-the-art receiver schemes based on EGC and MMSE criterion exploiting the same degree of channel knowledge.