Zero-Crossing Modulation for Wideband Systems Employing 1-Bit Quantization and Temporal Oversampling: Transceiver Design and Performance Evaluation

Next-generation wireless communications systems are anticipated to utilize the vast amount of available spectrum in the millimeter-wave and sub-terahertz bands above 100 G Hz to meet the ever-increasing demand for higher data rates. However, the analog-to-digital converter (ADC) power consumption is expected to be a major bottleneck if conventional system designs are employed at these frequencies. Instead, shifting the ADC resolution from the amplitude domain to the time domain by employing 1-bit quantization and temporal oversampling w.r.t. the Nyquist rate is expected to be more energy-efficient. Hence, we consider a system employing 1-bit quantization and temporal oversampling at the receiver, which operates on a wideband line-of-sight channel. We present a practical transceiver design for a zero-crossing modulation waveform, which combines faster-than-Nyquist signaling and runlength-limited (RLL) transmit sequences. To this aim, we derive four fixed-length finite-state machine RLL encoders enabling efficient transmit signal construction and soft-demapping at the receiver. Moreover, we propose a soft-output equalizer, which approximates maximum a posteriori RLL symbol detection. We evaluate the system performance in terms of peak-to-average-power ratio, coded block error rate, and a lower bound on the spectral efficiency (SE) w.r.t. a fractional power containment bandwidth. Our numerical results show that SEs of up to 4 bit/s/Hz are achievable with the presented transceiver design.