Advanced Receiver Architectures for Millimeter Wave Communications with Low-Resolution ADCs

Deploying large antenna arrays coupled with high-speed and high-resolution analog-to-digital converters (ADCs) leads to the high implementation cost and excessive power consumption in millimeter wave (mmWave) communication receivers. Although using low-resolution ADCs is a promising solution to address this problem, the performance degradation due to non-negligible quantization error and the large number of radio frequency (RF) chains are not desirable. In this article, we discuss advanced receiver architectures with low-resolution ADCs that further improve the spectral and energy efficiency tradeoff. To reduce both the number of RF chains and ADC bits, hybrid analog-and-digital beamforming is jointly considered with low-resolution ADCs. We explore the challenges in designing such a receiver and present key insights on how this advanced architecture overcomes such challenges. As an alternative low-resolution ADC receiver, we also introduce a receiver with learning-based detection. Such a receiver does not require explicit channel estimation, thereby is suitable for one-bit ADC systems. Finally, future challenges and research issues are discussed.