Joint impact of quantization and clipping on single- and multi-carrier block transmission systems

This work investigates the joint impact of quantization and clipping, caused by analog-to-digital converters (ADCs) with low bit resolutions, on single- and multi-carrier block transmission systems in wireless multipath environments. We consider single carrier block transmission with frequency domain equalization (SC-FDE) and the multi-carrier techniques OFDM and MC-CDMA. By approximating the ADC input as Gaussian distributed, the effective signal-to-noise ratio in the received signal and decision variables are derived and analyzed. The bit-error rate (BER) performance is simulated and compared for various constellations under different multipath conditions. The results reveal that frequency diversity is an effective measure to combat the joint impact of quantization and clipping. For the ADCs with moderate resolution bits, i.e., R = 5 and 4 bits, SC-FDE is shown to achieve the same performance as MC-CDMA. It is noted that due to the applied Gaussian approximation for the received signals, the derived SC-FDE results provide a lower bound on the performance of the systems under the influence of the ADC nonlinearity. This bound is tight, however, in case of rich multipath environments.