Coded Downlink Multi-user MC-CDMA System using Transmitter Pre-processing: Performance Results

In this treatise, we evaluate the error-rate (ER) performance of turbo-coded multi-carrier code division multiple access scheme (MC-CDMA) for downlink (DL) transmission. The transmitter pre-processing (TP) technique is a promising signal processing technique, which is carried out at the transmitter side to reduce the burden of each mobile station (MS) in the context of DL communication. We formulate minimum mean-square-error-aided TP matrix using noisy feedback of vector-quantized estimated channel information (CI) for frequency-division duplexing system. Clearly, we estimate the CI and perform vector quantization (VQ) at each MS and transmit the index of the quantized value through dedicated low rate noisy channel. Finally, we acquire CI of all active users using known estimation algorithm in order to build TP. We realize time-frequency domain signature sequence to support more user population. In particular, we analyze the ER performance of coded MC-CDMA system with TP for Stanford University Interim channel model. The ER curve shows that coded MC-CDMA system based on TP approach provides better performance with less signal-to-noise ratio while offering low complexity of MS. In addition, performance curve shows that there is an improvement in the ER performance when perfect CI is utilized to build TP matrix compared with noise-contaminated VQ-CI.