When Every Bit Counts in Quantized Beamforming: From CSI Feedback to Low-Resolution Hardware

Overview & Synopsis

Multiple-input multiple-output (MIMO) is a key technology in modern wireless networks, but its performance is often analyzed under ideal hardware assumptions. In practical implementations, however, quantization appears throughout the signal-processing chain, including channel state information (CSI) feedback, fronthaul signaling, beamforming coefficients, data converters, and finite-resolution phase shifters. These impairments do not act independently: they alter the channel information available for beamforming, constrain the feasible transmit signals, and can ultimately limit beamforming gain and interference suppression. This article provides a perspective on quantized beamforming by connecting its main sources, performance implications, and mitigation strategies. We discuss codebook-based CSI feedback, quantization-aware beamforming, low-resolution converter modeling, and finite-resolution hybrid beamforming, and use representative numerical examples to illustrate when quantization becomes a dominant performance bottleneck. We further highlight emerging directions in joint beamforming and quantization design, adaptive-resolution architectures, and new antenna technologies with discrete hardware constraints. The key message is that finite-resolution effects should be modeled explicitly and incorporated into the beamforming design rather than treated as an afterthought.