On the Capacity-Achieving Input of Channels With Phase Quantization

Several information-theoretic studies on channels with output quantization have identified the capacity-achieving input distributions for different fading 1-bit in-phase and quadrature (I/Q) quantization. However, an exact characterization of distribution multi-bit phase has not been provided. In this paper, we consider four channel models at identify optimal each model. We first a complex Gaussian $b$-bit phase-quantized prove that is rotated $2^b$-phase shift keying (PSK). The analysis then extended to multiple scenarios. show optimality $2^b$-PSK continues hold under noncoherent fast Rician when line-of-sight (LoS) present. When state information (CSI) available receiver, $\frac{2\pi}{2^b}$-symmetry constant amplitude as necessary sufficient conditions ergodic distribution; which satisfies. Finally, optimum power control scheme presented achieves capacity CSI also transmitter.