First- and Second-Moment Constrained Gaussian Channels

TL;DR

This paper analyzes the capacity limits of VLC systems with intensity modulation under various power constraints, revealing how first- and second-moment constraints influence capacity in different SNR regimes.

Contribution

It derives the asymptotic channel capacities for IM/DD VLC systems considering peak, first-, and second-moment constraints, highlighting their activity in different SNR regimes.

Findings

First- and second-moment constraints are rarely active simultaneously at low SNR.

Second-moment constraint is more restrictive at low SNR.

Capacity asymptotics differ significantly between high and low SNR regimes.

Abstract

This paper studies the channel capacity of intensity-modulation direct-detection (IM/DD) visible light communication (VLC) systems under both optical and electrical power constraints. Specifically, it derives the asymptotic capacities in the high and low signal-to-noise ratio (SNR) regimes under peak, first-moment, and second-moment constraints. The results show that first- and second-moment constraints are never simultaneously active in the asymptotic low-SNR regime, and only in few cases in the asymptotic high-SNR regime. Moreover, the second-moment constraint is more stringent in the asymptotic low-SNR regime than in the high-SNR regime.