Turbo OFDM-CDMA receiver with varying stepsize in multipath fading channels

The receiver performance can be improved dramatically by employing equalizer and turbo code. This paper investigates adaptive receivers with turbo decoder for orthogonal frequency division multiplexing-code division multiple access (OFDM-CDMA) systems in multipath channels. The LMS algorithm is used as the adaptive algorithm for the de-spreading equalizers which jointly perform equalization and single user detection in downlink multiuser environment. The varying stepsize equalizer jointed with turbo decoder is presented. Simulation results show that the system performances can substantially be improved if the adaptive equalizer can properly utilize the extrinsic information from the turbo decoder.