5 research outputs found
Statistical Modeling of FSO Fronthaul Channel for Drone-based Networks
We consider a drone-based communication network, where several drones hover
above an area and serve as mobile remote radio heads for a large number of
mobile users. We assume that the drones employ free space optical (FSO) links
for fronthauling of the users' data to a central unit. The main focus of this
paper is to quantify the geometric loss of the FSO channel arising from random
fluctuation of the position and orientation of the drones. In particular, we
derive upper and lower bounds, corresponding approximate expressions, and a
closed-form statistical model for the geometric loss. Simulation results
validate our derivations and quantify the FSO channel quality as a function of
the drone's instability, i.e., the variation of its position and orientation.Comment: This paper has been submitted to ICC 201
EH Modelling and Achievable Rate for FSO SWIPT Systems with Non-linear Photovoltaic Receivers
In this paper, we study optical simultaneous wireless information and power
transfer (SWIPT) systems, where a photovoltaic optical receiver (RX) is
illuminated by ambient light and an intensity-modulated free space optical
(FSO) signal. To facilitate simultaneous information reception and energy
harvesting (EH) at the RX, the received optical signal is first converted to an
electrical signal, and then, its alternating current (AC) and direct current
(DC) components are separated and utilized for information decoding and EH,
respectively. By accurately analysing the equivalent electrical circuit of the
photovoltaic RX, we model the current flow through the photovoltaic p-n
junction in both the low and high input power regimes using a two-diode model
of the p-n junction and we derive a closed-form non-linear EH model that
characterizes the harvested power at the RX. Furthermore, taking into account
the non-linear behaviour of the photovoltaic RX on information reception, we
derive the optimal distribution of the transmit information signal that
maximizes the achievable information rate. The proposed EH model is validated
by circuit simulation results. Furthermore, we compare with two baseline models
based on maximum power point (MPP) tracking at the RX and a single-diode p-n
junction model, respectively, and demonstrate that in contrast to the proposed
EH model, they are not able to fully capture the non-linearity of photovoltaic
optical RXs. Finally, our numerical results highlight that the proposed optimal
distribution of the transmit signal yields significantly higher achievable
information rates compared to uniformly distributed transmit signals, which are
optimal for linear optical information RXs.Comment: 7 pages, 6 figures, submitted for possible conference publicatio