AMCP/WG C-WPxx
AERONAUTICAL MOBILE COMMUNICATIONS PANEL
Working Group C
First Meeting
Montreal, Canada
11-19 October 2000
Agenda Item 7, 8, 12
Need to start work in considering new com systems in non VHF band
Presented by Philippe Renaud, Eurocontrol
SUMMARY
This paper highlights the potential medium term risk for a new VHF frequency congestion and
recommends to progress research activity for a mobile communication system operating in a non VHF
band.
1. Introduction
As part of a regular update cycle, the Eurocontrol Communication Strategy is being updated. Although
the formal approval has not been achieved, it can be considered confidently mature to be used as a
basis to highlight the need to progress further activities preferably on an international co-ordinated
basis.
2. Roadmap description
The Communication systems roadmap as described in the Eurocontrol Communications strategy is
depicted in Figure 2. As illustrated in this figure, the roadmap can be split into two steps.
2.1 First step
This first step is known with sufficient confidence. It is considered as stable and covers a period up to
around 2007. It involves few and simple systems.
During this step, voice services will be supported by:
a) a mixture of 8.33 and 25 kHz DSB-AM systems above FL 245 of 28 States (recently a high
level advisory group of the Eurocontrol Organisation – the ACG1 - and the EUR-Region
ICAO/FMG - have endorsed the horizontal extension of the 8.33 from 7 to 28 States) and
b) the 25 kHz DSB-AM below FL 245.
During this step, the data services will be supported by VDL Mode 2 as the enabler for the Link 2000+
programme for ATN services, as endorsed by a recent ACG. This VDL Mode 2/ATN will follow an
interim step for ATIS and DCL applications based on ACARS and as much as possible on VDL Mode
2/AOA to care of the VHF spectrum.
The systems used during this step are recognised to fulfil the requirements of the applications foreseen
to be in operation in the ECAC States at that period (for data as well as for voice).
1
ATM Consultative Group
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AMCP/WG C-WPxx
The main concern during this period is the provision of the required spectrum capacity. Indeed to
extend the number of services (e.g. new sectors (voice will not be discontinued but will be operated in
parallel to the datalink)), to introduce new concept/programmes (such as RNV 4, RVSM, Link 2000+),
and to sustain the traffic growth, more available spectrum is required.
As illustrated in the figure 1, resulting from simulations performed at Eurocontrol/FMG for the ICAOEUR Region on the expected frequency needs, a new VHF frequency congestion is expected in a time
frame which can be situated around 2007.
Figure 1 - Effect of expansions on the Percentage of Satisfied needs Vs Demand for Current 8.33 States
Therefore, there is an obvious need to make all the efforts to improve this situation. Eurocontrol, in
association with the European States, and the ICAO EUR-Office, are defining a framework for a better
VHF Frequency management process.
2.2 Next Step
The next step is composed with systems or extension of systems not yet endorsed. They are expected to
cope with:
a) The introduction of more demanding applications;
b) The foreseeable new congestion of the VHF band.
Among the systems supporting more demanding applications, the main, currently foreseen, systems in
Europe are:


VDL Mode 4 for Surveillance applications and for high QoS demanding Communication
applications (UAT and Mode S extended Squitter are also looked at as candidates for ADS-B
services);
VDL Mode 3 for high QoS demanding Data Communication applications and Voice.
With respect to avoiding new congestion of the VHF band, the main systems currently considered are:
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

The 8.33 in the lower airspace below FL 245 (known as “Vertical Expansion”) for voice services.
Although theoretically providing additional spectrum capacity (see figure 1), this measure is
anticipated to be not viable in the end taking into account the ratio of cost versus the probability of
successful implementation (the general aviation is impacted by the retrofit). However, the
feasibility is currently progressed and the decision is expected early 2001.
The usage of the VDL Mode 3 for voice and data service. This option may also prove to be a dead
end since VDL Mode 3 may not be more spectrum efficient than the 8.33 considering the
preliminary results on frequency protection for D8PSK and the difficulty to start a migration in the
European Spectrum environment. However, the feasibility of this option will be progressed and
results are expected in 2001.
As it can be seen, all the systems considered for communication services are operating in the crowded
VHF band.
Note: some systems currently considered (such as Gatelink) or systems that could be re-considered
later on (such as Mode S datalink), are not expected to provide a global solution to address the VHF
spectrum congestion issue.
3. Recommendation
As a mitigation, and in parallel to the work on-going on the systems considered by AMCP, it is
recommended to urgently progress R/D activity to identify an appropriate system operating in a
non VHF band able to fulfil the future aeronautical communication requirements, and which
should be operational around 2010.
For a successful achievement, it is important that the work is carried out in a co-ordinated basis
with all concerned parties. Therefore it is recommended to progress this work inside the
AMCP/WGC.
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Additional sectors above FL 245 in 28 States (horizontal expansion)
AMCP/WG C-WPxx
8.33 kHz DSB-AM
Initial deployement above FL 245 in 7 States
Additional sectors below FL 245 (vertical expansion)
Voice
services
25 kHz DSB-AM
VDL Mode 3 or new system
VDL Mode 4 for surveillance
ATN/VDL Mode 3/4
or new system for
safety critical com
ATS application
Data
services
DCL-ATIS/AOA/VDL M2
ATN/VDL M2
DCL-ATIS/ACARS
Wireless Gatelink (in airports)
ATN/Mode S (in
congested regions)
Optimised management of the Frequencies
2000
2005
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Figure 2 – Roadmap for Mobile subnetworks in Europe
2010
Specific
areas
AMCP/WG C-WPxx
: First step
: Second step
: Feasibility – assessment - R/D
: First step
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