The Noncoherent Rician Fading Channel -- Part I : Structure of the Capacity-Achieving Input
<|reference_start|>The Noncoherent Rician Fading Channel -- Part I : Structure of the Capacity-Achieving Input: Transmission of information over a discrete-time memoryless Rician fading channel is considered where neither the receiver nor the transmitter knows the fading coefficients. First the structure of the capacity-achieving input signals is investigated when the input is constrained to have limited peakedness by imposing either a fourth moment or a peak constraint. When the input is subject to second and fourth moment limitations, it is shown that the capacity-achieving input amplitude distribution is discrete with a finite number of mass points in the low-power regime. A similar discrete structure for the optimal amplitude is proven over the entire SNR range when there is only a peak power constraint. The Rician fading with phase-noise channel model, where there is phase uncertainty in the specular component, is analyzed. For this model it is shown that, with only an average power constraint, the capacity-achieving input amplitude is discrete with a finite number of levels. For the classical average power limited Rician fading channel, it is proven that the optimal input amplitude distribution has bounded support.<|reference_end|>
@article{gursoy2005the,
    title={The Noncoherent Rician Fading Channel -- Part I : Structure of the
  Capacity-Achieving Input},
    author={Mustafa Cenk Gursoy, H. Vincent Poor and Sergio Verdu},
    journal={arXiv preprint arXiv:cs/0501066},
    year={2005},
    doi={10.1109/TWC.2005.853970},
    archivePrefix={arXiv},
    eprint={cs/0501066},
    primaryClass={cs.IT math.IT}
}