3 research outputs found
Performance of Multibeam Very High Throughput Satellite Systems Based on FSO Feeder Links with HPA Nonlinearity
Due to recent advances in laser satellite communications technology,
free-space optical (FSO) links are presented as an ideal alternative to the
conventional radio frequency (RF) feeder links of the geostationary satellite
for next generation very high throughput satellite (VHTS) systems. In this
paper, we investigate the performance of multibeam VHTS systems that account
for nonlinear high power amplifiers at the transparent fixed gain satellite
transponder. Specifically, we consider the forward link of such systems, where
the RF user link is assumed to follow the shadowed Rician model and the FSO
feeder link is modeled by the Gamma-Gamma distribution in the presence of beam
wander and pointing errors where it operates under either the intensity
modulation with direct detection or the heterodyne detection. Moreover,
zero-forcing precoder is employed to mitigate the effect of inter-beam
interference caused by the aggressive frequency reuse in the user link. The
performance of the system under study is evaluated in terms of the outage
probability, the average bit-error rate (BER), and the ergodic capacity that
are derived in exact closed-forms in terms of the bivariate Meijer's G
function. Simple asymptotic results for the outage probability and the average
BER are also obtained at high signal-to-noise ratio.Comment: Accepted for publication in IEEE Transactions on Wireless
Communication
A PHY Layer Security Analysis of a Hybrid High Throughput Satellite with an Optical Feeder Link
Hybrid terrestrial-satellite (HTS) communication systems have gained a
tremendous amount of interest recently due to the high demand for global high
data rates. Conventional satellite communications operate in the conventional
Ku (12 GHz) and Ka (26.5-40 GHz) radio-frequency bands for assessing the feeder
link, between the ground gateway and the satellite. Nevertheless, with the aim
to provide hundreds of Mbps of throughput per each user, free-space optical
(FSO) feeder links have been proposed to fulfill these high data rates
requirements. In this paper, we investigate the physical layer security
performance for a hybrid very high throughput satellite communication system
with an FSO feeder link. In particular, the satellite receives the incoming
optical wave from an appropriate optical ground station, carrying the data
symbols of users through various optical apertures and combines them using
the selection combining technique. Henceforth, the decoded and regenerated
information signals of the users are zero-forcing (ZF) precoded in order to
cancel the interbeam interference at the end-users. The communication is
performed under the presence of malicious eavesdroppers nodes at both hops.
Statistical properties of the signal-to-noise ratio of the legitimate and
wiretap links at each hop are derived, based on which the intercept probability
metric is evaluated. The derived results show that above a certain number of
optical apertures, the secrecy level is not improved further. Also, the
system's secrecy is improved using ZF precoding compared to the no-precoding
scenario for some specific nodes' positions. All the derived analytical
expressions are validated through Monte Carlo simulations.Comment: 17 pages, 10 figure
A Key 6G Challenge and Opportunity -- Connecting the Remaining 4 Billions: A Survey on Rural Connectivity
Providing connectivity to around half of the World population living in rural
or underprivileged areas is a tremendous challenge, but also a unique
opportunity. In this paper, a survey of technologies for providing connectivity
to rural areas, and that can help address this challenge, is provided.
Fronthaul and backhaul techniques are discussed. In addition, energy and cost
efficiency of the studied technologies are analyzed. Typical application
scenarios in rural areas are discussed, and several country-specific use cases
are surveyed. Directions for future evolution of rural connectivity are
outlined