Iterative and Diversity Techniques for Uplink MC-CDMA Mobile Systems With Full Load

Iterative and diversity techniques are two of the most effective techniques for uplink multicarrier code-division multiple-access (MC-CDMA) systems. However, there is still no knowledge on how to efficiently combine these techniques to design high-performance uplink receivers when there is a complexity constraint. In this paper, we compare the performance and the complexity of MC-CDMA systems with and without iterative detectors and multiple-receive-antenna arrays. Through extensive simulation, we demonstrate that the following four combinations are good tradeoffs between complexity and performance: a single-antenna receiver with an iterative parallel-interference-cancellation (PIC) detector initialized by a matched filter (MF) with three iterations, a two-antenna receiver with a minimum-mean-square-error multiuser detector or an iterative PIC detector initialized by an MF with two iterations, and a four-antenna receiver with a simple MF detector. Therefore, noniterative detectors with multiple-receive-antenna arrays can be used to replace iterative detectors and reduce complexity, which is a promising solution for fourth-generation (4G) uplink MC-CDMA systems, where multiple-receive antennas are available at the base stations. In this paper, we also briefly discuss pilot-aided channel estimation using the weighted-delay-profile technique and investigate the impact of channel-estimation error in different environments.