Efficient Hybrid Amplitude-Phase Quantization for Multi-Antenna Relay System

This letter explores relay quantization in multi-antenna quantize–forward (QF) relay systems. Existing methods, such as uniform phase quantization (U-PQ) and uniform amplitude-phase quantization (U-APQ), suffer from performance saturation and high memory demands. To overcome these limitations, we propose hybrid amplitude-phase quantization (H-APQ), which adaptively quantizes received signal amplitudes based on their relative magnitudes while applying uniform quantization to individual phases. H-APQ significantly reduces memory consumption at the relay while maintaining strong overall performance, offering an efficient solution for multiple-input multiple-output (MIMO) QF relay systems.