Constant Paul Marie Jozef Baggen

An illumination perspective on visible light communications

Visible light communications are the offspring of well studied infrared wireless systems and can form a promising enhancement of future illumination infrastructures with communication functionalities. However, supporting data rates of hundreds of megabits per second cannot come for free with respect to lighting system costs. This article addresses the limitations that lighting requirements impose on VLC systems in terms of modulation bandwidth, received power, and cost constraints. The achievable data rates of joint VLC and illumination systems are discussed, and examples of possible applications are provided.

Square Root approximation to the Poisson Channel

Starting from the Poisson model we present a channel model for optical communications, called the Square Root (SR) Channel, in which the noise is additive Gaussian with constant variance. Initially, we prove that for large peak or average power, the transmission rate of a Poisson Channel when coding and decoding methods for the SR Channel are used, converges to the capacity of the Poisson Channel. Then, we derive bounds and asymptotic expressions for the capacity of the SR Channel, and compare them to those of other optical channel models. Finally, signal-independent noise sources are discussed.

The optical illumination channel

The optical illumination channel is defined as a communication channel associated with a lighting source whose primary functionality is to provide illumination. A description of this channel and the associated noise sources including thermal noise from the receiver electronics, ambient light noise from other light sources and signal dependent noise due to the stochastic nature of the optical signal is provided. We show that under a square root transform of the received signal and by proper signaling the channel converts into a unitary channel of the same form as the wireless radio additive white Gaussian noise (AWGN) channel with peak and average power constraints. Therefore this transform converts the optical illumination channel into a well understood format. The optimum detector is investigated. The proposed square root channel is compared with other common optical channels, in terms of power, and path losses where its simplicity is highlighted. The capacity as a function of the average illumination level of such a channel is calculated and investigated. Finally real scenarios are described where the applicability of the model is shown clearly.

On the diamond code construction

We introduce a new error correcting code, which we call the diamond code. Diamond codes combine the error correcting capabilities of product codes and the reduced memory requirements from CIRC, the code applied in the CD system.

On band-limited additive Gaussian noise channels in the presence of sampling jitter

One of the topics in information theory is the study of communication through bandlimited waveform channels corrupted by Gaussian noise. In practical receiver implementations, sampling is used to obtain a digital representation of the received signal which is amenable to advanced processing. We consider information theoretic consequences of nonideal uniform sampling combined with additive Gaussian noise. In particular, we find that for Gaussian distributed waveforms, sampling jitter, just like additive noise, leads to a fundamental limit on reliable communication speed.<<ETX>>