This paper considers the use of SDMA (Space Division Multiple Access) techniques for the uplink of MC-CDMA systems (MultiCarrier - Coded Division Multiple Access) where the transmitted signals face strong nonlinear distortion effects.
The signal transmitted by each MT (Mobile Terminal) is submitted to a nonlinear operation consisting on a clipping device, followed by a frequency-domain filtering operation, so as to reduce the envelope fluctuations and PMEPR (Peak-to-Mean Envelope Power Ratio) while maintaining the spectral occupation of conventional MC-CDMA signals. At the BS (Base Station), an iterative receiver employing multiple antennas jointly performs turbo MUD (MultiUser Detection) and the estimation and cancellation of nonlinear distortion effects.
Our performance results show that the proposed receiver structures allows good performance, that can be very close to the ones obtained with linear transmitters, even for high system load and/or when a very low-PMEPR MC-CDMA transmission is intended for each MT.