Power Allocation for Fading Channels with Peak-to-Average Power Constraints

TL;DR

This paper studies power allocation strategies under peak-to-average power constraints for Nakagami-m fading channels, revealing that error floors exist and that capacities remain close to unconstrained cases even with strict power ratio limits.

Contribution

It derives optimal power allocation schemes for both delay-limited and ergodic fading channels under peak-to-average power constraints, extending existing models to arbitrary input distributions.

Findings

Error floors are present at finite peak-to-average power ratios.

Capacities with peak-to-average constraints are close to unconstrained capacities.

Optimal power allocation rules are derived for different fading scenarios.

Abstract

Power allocation with peak-to-average power ratio constraints is investigated for transmission over Nakagami-m fading channels with arbitrary input distributions. In the case of delay-limited block-fading channels, we find the solution to the minimum outage power allocation scheme with peak-to-average power constraints and arbitrary input distributions, and show that the signal-to-noise ratio exponent for any finite peak-to-average power ratio is the same as that of the peak-power limited problem, resulting in an error floor. In the case of the ergodic fully-interleaved channel, we find the power allocation rule that yields the maximal information rate for an arbitrary input distribution and show that capacities with peak-to-average power ratio constraints, even for small ratios, are very close to capacities without peak-power restrictions.