FINAL REPORT - Stakeholders - Ofcom

to aviation. As discussed in section 3.4.5.7, allocations are actually being moved out-ofband
over the next few years (i.e. fixed services cease usage by 2015). The issue
currently is whether other technologies such as UWB, or harmonics from certain other
frequencies (e.g. TV broadcasting operating around 800 MHz), will affect operations (and
are therefore allowable). This is currently being researched at an ICAO and
EUROCONTROL level.
3.4.10 Summary Of Possible Overall Spectral Efficiency Improvements
This section attempts to highlight any improvements that could be made to increase
spectrum efficiency. The possible mechanisms for carrying out these improvements are
discussed in further sections below.
LORAN-C – the allocation is fixed on a central frequency, which will not change in the
foreseeable future (due to non-aviation requirements). Although there is a possibility of
reducing the bandwidth, the likelihood is that 20 kHz is the minimum required to provide a
safety-of-life service (e.g. to maritime users), and therefore should be maintained.
NDB – competition exists from broadcasting and maritime mobile. Broadcasting at the
upper and lower ends of the band may be able to increase its allocation if the
decommissioning of NDBs permits. ICAO recommends that the overall allocations are
maintained until 2020 – nevertheless, the 255-283.5 kHz band is currently shared
between MRNS, ARNS and broadcasting, thus constraints on broadcasting may be able
to be removed in-band before 2020, or more allocation sharing permitted in frequencies
over 283.5 kHz. General Aviation is the main blocking point to the decommissioning –
methods should therefore be found to replace the GA requirement for NDBs. Scenarios
could include:
• Equipping GA with RNAV capability (in practice, an RNAV computer and the
ability to receive multiple modes of navigation inputs) or;
• Equipping GA with GNSS capability.
Marker Beacons – no change foreseen.
ILS – the ILS frequency allocation shall remain protected; channelisation is fixed.
However, non-interfering secondary allocations may be granted – local augmentation
systems for GNSS, such as GBAS for landing systems, may be allocated frequencies
within ILS bands. Geographical separation criteria should be implemented to ensure
efficient frequency usage. However, with the withdrawal of VORs, it may be more prudent
to site GBAS in the upper part of the allocation to VHF ARNS.
VOR – in common with ILS, channelisation is fixed. The frequency allocation is likely to
remain; however, actual usage will decrease in the long term as VORs are
decommissioned. Plans should be drawn up on how best to re-use the available
frequencies; competing services include VDL Mode 4 datalink, GBAS and ILS. Again,
General Aviation has current requirements for VORs; replacement strategies will be
identical as those for NDBs.
DME – due to the hard double or triple-pairing with ILS, MLS and VOR, DME allocations
can be very inefficient. Reduction of the requirements for triple pairing (due to
decommissioning of the VORs) may lead to greater spectral efficiency. Possible
opportunities therefore include:
Investigating the efficiency savings made by de-tripling or de-coupling the ILS, MLS, VOR
and DME frequencies where appropriate.
In the medium-term, the usage of the new E5/L5 frequencies (even with the limits
imposed) will lead to interference between GNSS and DME. The solution of moving all
DME out of the GNSS band has been found to be unworkable in Europe. However, this
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