Figure 1: VDES Frequency Plan and
Subsystem Definitions [1]
The aim of this special issue of IJSC&N has been to shed light on
potential use cases and relevant technologies applicable to VDES. The
first part of this special issue brings together six papers selected
among manuscripts submitted to this call addressing verity of topics
ranging from channel modelling, antenna technologies, random access
protocol as well as geo-localization and ranging applications.
In the paper titled “Satellite forward VDES channel modeling and impact
on higher‐layer performance”, G. Giambene et al. use the collected data
from a measurement campaign to develop an ON-OFF model for the VDE-SAT
downlink channel taking into account the multipath due to the surface
reflections and wide-beam receiving antenna. The channel model is
subsequently used to assess the effect of link layer coding schemes to
combat packet loss during deep signal fading. The proposed technique is
particularly important for VDE-SAT downlink broadcasting content such as
ice charts to multiple users.
A review of the state-of-the art regarding on-board antenna technologies
in VHF bands, particularly for small satellites and CubeSats in Low
Earth Orbit (LEO), has been reported by V. Gomez-Guillamon Buendía et.
al in their paper titled “Review of antenna technologies for very high
frequency Data Exchange Systems”. The paper provides a comparative
study of antennas for VDES applications taking into account relevant
performance metrics.
The third paper in this special issue entitled “Performance bounds for
VDE‐SAT R‐Mode” by J. Safar et al., reports on the growing interest to
utilize VDES satellite and terrestrial components to deliver positioning
and timing services to vessels, as commonly referred to as ranging mode
or R-Mode. The paper in particular investigates the feasibility of using
satellite VDES transmission by establishing statistical performance
bounds on the ranging error. Reported results complement previous
findings of the same authors on the performance bounds obtained for
terrestrial VDE waveforms.
The fourth paper entitled “VDES R‐Mode performance analysis and
experimental results” by M. Wirsing et al., applies signal processing
techniques such as Kalman filtering for position and velocity tracking
based on experimental data collected from VDES terrestrial trails. Using
the experiment results, authors remark that terrestrial VDES R-Mode is
capable of achieving a 95th-percentile horizontal position error of 22
m.
In the paper entitled, “VDES R‐Mode: Vulnerability analysis and
mitigation concepts” F. Lázaro et al., report on the use of VDES and
its potential vulnerability as a contingency for maritime positioning
and navigation systems in case of disruption of the Global Navigation
Satellite Systems (GNSS). Authors propose an authentication method for
VDES navigation messages.
Finally, in the sixth paper of this special issue R. Andreotti et al. in
their paper titled “On-Field Test Campaign Performance of VDE-SAT Link
ID 20 over Norsat-2 LEO Satellite”, analyse experiment results of their
test campaign based on VDE-SAT uplink random access channel
transmissions. The paper also reports on the use of demodulation
techniques to successfully decode overlapping messages, confirming the
robustness of the VDES protocol against self-interference from random
access channel transmissions.
In closing this editorial message, we would like to thank all authors of
submitted manuscripts for their excellent contributions. We would also
like to recognize the contribution of reviewers for their valuable
comments and suggestions to enhance the quality of the papers.