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Low SNR Capacity of Fading Channels with Peak and Average Power Constraints

Vignesh Sethuraman·Bruce Hajek
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Abstract

Flat-fading channels that are correlated in time are considered under peak and average power constraints. For discrete-time channels, a new upper bound on the capacity per unit time is derived. A low SNR analysis of a full-scattering vector channel is used to derive a complimentary lower bound. Together, these bounds allow us to identify the exact scaling of channel capacity for a fixed peak to average ratio, as the average power converges to zero. The upper bound is also asymptotically tight as the average power converges to zero for a fixed peak power. For a continuous time infinite bandwidth channel, Viterbi identified the capacity for M-FSK modulation. Recently, Zhang and Laneman showed that the capacity can be achieved with non-bursty signaling (QPSK). An additional contribution of this paper is to obtain similar results under peak and average power constraints.

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Vignesh Sethuraman, Bruce Hajek. 2006-04-13. Low SNR Capacity of Fading Channels with Peak and Average Power Constraints. https://arxiv.org/abs/cs/0604049

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