Optimal Power Allocation Between Beam Tracking and Symbol Detection
Channels in a Free-Space Optical Communications Receiver
Abstract
Free-space optical (FSO) communications will play an important role in
the backhaul of future generation of wireless networks in order to
support high data rates. Because of narrow beamwidth inherent to an
optical signal, acquisition and tracking form an important component of
any FSO communication system. In this study, we have analyzed the
optimization of received power allocation between tracking and data
channels in an FSO receiver. The objective function that is optimized
(minimized) are the probability of error and the probability of outage,
and the optimization of power allocation is carried out as a function of
parameters such as noise power, pointing error variance, pointing error
correlation coefficient, and the threshold of outage. We have analyzed
the optimization concerning the lognormal and exponentiated Weibull
fading scenarios as well. We learn that the optimal power allocation is
a function of the received signal-to-noise ratio: a lower
signal-to-noise ratio dictates that a higher fraction of received power
should be diverted to the tracking channel and vice versa.