Ricerc@Sapienza

This paper presents a novel space-time recursive least-squares adaptive algorithm, which performs filter coefficients updates in space and postponed filtering in time. The algorithm is used for intersymbol interference suppression in optical camera communications, which is a subgroup of visible light communication systems. Optical camera communications uses image sensor receivers, as those available in smartphones, tablets, and laptops, to detect changes in light intensity in order to allow data transmission.

A new blind estimator of the sampling phase is proposed to support fractionally spaced equalization in underwater digital links employing pulse position modulation. Stemming from the relationship between the “spikiness” of the channel impulse response and the deviation from Gaussianity of the received signal, the sampling phase is estimated by exploiting non-Gaussianity measures offered by nonlinear statistics. In particular, the fourth order (kurtosis) and the first order nonlinear sample moments are considered and the resulting receiver performance is analyzed.

Underwater acoustic digital communications suffer from inter-symbol interference deriving from signal distortions caused by the channel propagation. Facing such kind of impairment becomes particularly challenging when dealing with shallow water scenarios characterized by short channel coherence time and large delay spread caused by time-varying multipath effects. Channel equalization operated on the received signal represents a crucial issue in order to mitigate the effect of inter-symbol interference and improve the link reliability.