Is Phase Shift Keying Optimal for Channels with Phase-Quantized Output?
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This paper establishes the capacity of additive white Gaussian noise (AWGN) channels with phase-quantized output. We show that a rotated 2^b-phase shift keying scheme is the capacity-achieving input distribution for a complex AWGN channel with b-bit phase quantization. The result is then used to establish the expression for the channel capacity as a function of average power constraint P and quantization bits b. The outage performance of phase-quantized system is also investigated for the case of Rayleigh fading. Our findings suggest the existence of a threshold in the rate R, above which the decay exponent of the outage probability changes abruptly. In fact, this threshold effect in the decay exponent causes 2^b-PSK to have suboptimal outage performance at high SNR.
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