Overdemodulation for High-Performance Receivers with Low-Resolution ADC

The design of the analog demodulator for receivers with low-resolution analog-to-digital converters (ADCs) is investigated. For infinite ADC resolution, demodulation to baseband with M=2 orthogonal sinusoidal functions (quadrature demodulation) is an optimum design choice with respect to system performance. For receivers which are restricted to ADCs with low amplitude resolution, we show that this classical approach is suboptimal under an estimation and information theoretic perspective. To this end, we analyze the theoretical channel parameter estimation performance (Fisher information) under an ideal receive situation when forming M>2 analog demodulation channels prior to low-complexity 1-bit ADCs. To demonstrate the impact of overdemodulation for communication problems, we also provide a brief discussion on the achievable transmission rates (Shannon information) with 1-bit quantization of M>2 demodulation channels.