Evolution of Digital Iterative Receiver for Multicarrier Code-Division Multiple-Access Signals with Low Peak-to-Mean Envelope Power Ratio Value

The uplink transmission in multicarrier Code-Division Multiple-Access (MC-CDMA) systems was experimentally studied. Multicarrier signals such as MC-CDMA signals have large envelope repetition and a high Peak-to-Mean Envelope Power Ratio (PMEPR), which creates amplification complications. This is mostly important for the uplink communication, while efficient low-cost power amplification is attractive at the Mobile Terminals (MTs). Generally, the transmission over timedispersive channels destroys the orthogonality between spreading codes, which may lead to significant multiple-access interference levels. To minimize the envelope fluctuations of the transmitted signals, while maintaining the spectral efficiency, the MC-CDMA signal related to each MT is submitted to a clipping device, followed by a frequency domain filtering operation. However, the nonlinear distortion effects can be high when an MC-CDMA transmitter with reduced envelope fluctuations is intended. Our performance results prove that the proposed receiver structure allow good performances, very close to the linear receiver ones, even for high system load and/or when a PMEPR as low as 1.7 dB is intentional for each MT.