1. Vol. I - ICAO Spectrum Strategy Vol. II - Frequency Planning
ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation
Vol. I - ICAO Spectrum Strategy
Vol. II - Frequency Planning
Aeronautical Spectrum Workshop
Preparation for WRC-15
Lima, Peru, March 2013
Loftur Jónasson
ICAO

2. In my first presentation, yesterday – I showed you this same slide, which gives a rough overview of aeronautical frequency spectrum allocations, spanning long wave with Non Directional Beacons, through Short Wave or HF with its long-distance voice communications, VHF – catering to VOR, ILS, Ground based augmentation systems and of course direct Pilot to Controller voice.
UHF – with ILS Glide Path, DME, Primary and secondary Radar – radio altimeters – weather radar.
Well the good news is that we have the spectrum use of all these systems described in one book – the Frequency spectrum Handbook or ICAO Document 9718.

3. Overview Volume I – ICAO Spectrum Strategy and Policies
Volume II – ICAO Frequency Assignment Planning
Volume 1 of the Handbook, addresses Spectrum Management issues and ICAO policies, including the results from WRC-12 and the status of the ICAO preparatory work for ITU WRC-15. This presentation provides a high level overview of the ICAO spectrum policies.
The new Volume II of the Handbook addresses Frequency Assignment Planning, it includes details on frequency assignment planning for VHF Communication Systems.
Implementation of the Frequency assignment planning criteria in Volume II is complemented by the frequency assignment planning software “Frequency Finder” which supports Regional frequency assignment planning and provides the mechanism for developing the ICAO Global frequency lists.

4. Handbook Volume I Spectrum Strategy and Policies
Overall ICAO Spectrum Policy
(approved by Council)
ICAO Spectrum Strategy
Long term spectrum use of current and future radio systems
ICAO Spectrum Policy Statements
Specific actions to assist in meeting the Strategic Objectives
ICAO Position for future WRC’s
Medium and long term availability of spectrum for aviation
The Overall ICAO Spectrum Strategy or Policy has been developed as a hierarchy of three related elements:
The ICAO Spectrum Strategy is a collection of high level statements of the spectrum necessary to support the implementation of current and future global and regional planning for CNS systems. In the latest draft update of the Handbook Volume I, the Spectrum Strategy is presented in a number of statements, for each frequency band in use by aeronautical CNS systems. The Spectrum strategy is intended to address the spectrum required for current and future:
air/ground communication systems
radionavigation systems and
on-board stand alone systems
For each aeronautical frequency band, the Spectrum Strategy identifies the current and future systems that are considered essential to support air transport, and the time scale within which these systems are expected to operate. The ICAO spectrum strategy is intended to facilitate technological innovation, to maintain and enhance the safety of global air transport. The strategy places due account to efficient spectrum utilization.
Individual ICAO Spectrum Policy Statements have been developed for each frequency band used by aviation, providing for specific actions that have been identified to assist in meeting the ICAO Spectrum Strategic Objectives..
These policy statements concentrate on the protection of each frequency band.
The Policy Statements provide the ICAO policy on specific provisions in the ITU Radio Regulations that include conditions for using that frequency band.
The Policy Statements provide a comprehensive ICAO policy with regard to spectrum utilization and availability for aviation, and are used, when and where necessary, to state aeronautical spectrum requirements.
The ICAO position for World Radiocommunication Conferences is developed within the framework of the Spectrum Strategy and concentrates on items and frequency bands which have been placed on the agenda of a specific future WRC. The ICAO position considers in a greater detail the spectrum availability (or spectrum capacity) for current and future systems, and addresses the Radio Regulatory conditions of protecting spectrum from harmful interference, in particular when harmful interference is expected from non-aeronautical systems.
While the ICAO Position for a World Radiocommunicaition Conference of course receives the most attention, and is subject to a review by States, all elements of the ICAO spectrum strategy or policy are approved by Council.

5. Handbook Volume I Spectrum Strategy and Policies
Background material in the Handbook, (Volume I)
(1)
Role of ICAO
In ITU-R (Study Groups) and in Regional Telecommunication Organizations
At ITU World Radiocommunication Conferences
In frequency coordination and registration (also ITU)
Role of the ITU and Regional Telecommunication Organizations
Develop technical material (ITU-R Study Groups)
Amend Radio Regulations (at WRCs)
In addition to the policy material that has been incorporated in the Handbook, Volume I, you will also find background material that has been included to support the common understanding to the various processes involved in aeronautical and general frequency management. This background material includes:
The role of ICAO in spectrum management and describes the participation of ICAO in ITU-R Study groups, where ICAO can present proposals for ITU-R Recommendations and Reports that address aeronautical issues, mainly related to the protection of aeronautical services from harmful interference from non-aeronautical services using the same or nearby frequency bands. Also in highlights the participation of ICAO in the work of Regional Telecommunication Organizations, in particular on the preparation of Regional positions for ITU World Radiocommunication Conferences.
The Handbook describes the role of ICAO in the ITU World Radio Communication Conferences, where ICAO participates as an “Observer in an advisory capacity”. Advisory capacity means that ICAO can fully participate in the discussions and present papers for review by the Conference.
Volume I of the handbook also highlights the current practices of frequency coordination, frequency assignment planning and frequency registration, by the ICAO Regional Offices, and by ITU through the application of the Master International Frequency Register.
And, the Handbook describes the role of the ITU and the Regional Telecommunication Organizations like CITEL, in the context of World Radiocommunication Conference preparations.

6. Handbook Volume I Spectrum Strategy and Policies
Background material in the Handbook, (Volume I)
(2)
Statement of frequency allocations and technical details (Chapter 7)
Frequency allocations and footnotes in ITU Radio Regulations
Aviation use
Commentary (specific comments on ITU and ICAO review In frequency coordination and registration (also ITU)
Interference protection considerations
Finally, Chapter 7 of the Handbook, Volume I, which is the main Chapter of the Handbook, includes an up-to-date overview of the spectrum allocations to aeronautical services. This includes the relevant footnotes to aeronautical frequency allocations, copied from the Radio Regulations. The chapter provides a detailed description of the aviation use of each frequency band allocation, and it includes a commentary section which reviews particular developments on the radio-regulatory provisions and the material developed in ITU-R, as well as specific relevant details on the ICAO review of spectrum utilization.
Chapter 9 addresses regulatory provisions and practical considerations on the prevention and removal of harmful interference.

7. Handbook Volume II Frequency assignment planning
Purpose
Provide globally harmonized frequency assignment planning criteria and guidance material to support the application of SARPs in Annex 10, Vol. V
Developed in conjunction with the revisions to Annex 10, Vol. V
Developed by ACP Working Group F
Implementation through Regional Air Navigation Agreement by PIRG
To support the development of Global COM lists and the Global Air Navigation Plan
The rest of this presentation is on the new Volume II of the RF Handbook.
The purpose of the new Volume II is to provide globally harmonized frequency assignment planning criteria for aeronautical radio communication and navigation systems.
These criteria facilitate the protection of ICAO standardized systems on a uniform basis. These criteria also introduce flexibility in actual frequency assignment planning and support efficient use of the available spectrum. Volume II of the Handbook incorporates details on recent developments on the use of the VHF band – 137 MHz, such as the introduction of 8.33 kHz channel spacing and air/ground data link.
The material in the Handbook Volume II was developed in conjunction with a revision of the SARPS in Annex 10 for VHF air/ground communication systems. Guidance material previously contained in Attachment A to Annex 10, Volume V has now been removed from the SARPs; and relevant and more comprehensive material has been accommodated in the Handbook. These revisions to Annex 10 are were adopted by Council a couple of weeks ago and will become applicable in November this year.
In order to provide a global forum for the development of the frequency assignment planning criteria, ACP Working Group F was given the task to coordinate and review the planning criteria. The material in the Handbook is an update to the planning criteria currently in use by the ICAO Regions. Due account was given to regional differences in the actual use of the frequency band – 137 MHz.
Although the frequency assignment planning criteira presented in the Handbook, Volume II update the current criteria used in the ICAO Regions, implementation of these new criteria require amendments to the Regional Air Navigation Plans. Such amendments have to be developed within each Region and approved by the relevant Regional Planning and implementation Groups. When developing the relevant amendments to the Regional Plans, Regions can incorporate additional considerations, if necessary, with regard to the deployment of these frequency bands. If necessary or desired, the ICAO Secretariat (HQ) can assist in developing harmonized proposals for amending the Regional Air Navigation Plans to support harmonization between the relevant provisions in the Regional Air Navigation Plans.
The frequency assignment planning criteria in the Handbook (Volume II) support the development of global frequency lists or COM lists and a globally harmonized assessment of the compatibility of frequency assignments. One of the elements of the global frequency lists is to facilitate interregional coordination of frequency assignments.

8. Handbook Volume II Frequency assignment planning
Chapter 1 (1) General methodology
General methodology for compatibility analysis
General model for compatibility assessment
Based on:
Protection of desired signal at receiver input
Not to exceed maximum permissible distortion of receiver output signal
Chapter 1 contains the general methodology to assess compatibility between the desired communication or navigation frequency and any undesired signal that may potentially cause harmful interference. For all radio systems in Annex 10, ICAO has established a protection ratio (signals in space) that would provide adequate protection of these systems from harmful interference. These are intra-system protection requirements and cannot be applied when the spectral characteristics of the interfering signal differs from those of the desired signal.
The radio-frequency protection ratios (desired-to-undesired signal ratio) have been developed to ensure that the distortion of the output of an aeronautical communication or navigation receiver does not exceed the operationally acceptable values.
The desired-to-undesired signal ratio is an essential element of the frequency assignment planning criteria. The general model can also be used to establish compatibility requirements, through measurements, when the radio-frequency characteristics differ from the desired input (RF) signal.
The general model allows for the calculation of signal levels (at the antenna or at the receiver input) and to establish separation criteria (geographical or frequency) to be satisfied to protect the desired signal from harmful interference.

9. Handbook Volume II Frequency assignment planning
Chapter 1 (2) General methodology
Propagation model
Based on free space propagation
(Re. Recommendation ITU-R P.525)
Propagation model does not accommodate certain phenomena which are difficult to predict such as
Changes in the refractive index of the atmosphere
Ducting
ITU has developed propagation curves for aeronautical communication and navigation systems (Recommendation ITU-R P.528)
Another essential element of the frequency assignment planning criteria is the radio-frequency propagation model that is to be applied. In aviation we normally use the free space propagation model as specified in Recommendation ITU-R P.525.
Propagation of radio waves is affected by the refractive index of the atmosphere and allows VHF frequencies to be received beyond the optical horizon. Radio line of sight normally employs a 4/3 Earth radius to calculate the distance (path) over which the propagation of the (VHF) radio signals can be considered with the free space propagation formulas. This complies with the so-called “standard atmosphere”. In aeronautical frequency assignment planning, variations of the refractive index are not considered. Similarly, temporary propagation phenomena such as ducting is not accommodated in frequency assignment planning.
The ITU has developed a set of aeronautical propagation curves for 125 MHz, 300 MHz, 1200 MHz and 5100 MHz. These may be used for a more precise estimation of the propagation of aeronautical radio frequencies. These curves are based on the IF-77 model and were developed in the late ninteenseventies. They basically apply to temperate regions, that is, between latitudes of about 25 – 55 degrees, north or south.

10. Handbook Volume II Frequency assignment planning
Chapter 2 (1)
Frequency assignment planning criteria for VHF air-ground communication systems
Interference model (co-frequency separation)
Conforms to the general methodology in Chapter 1
Model for establishing separation distances to prevent air-to-air interference:
Minimum separation between stations A and B: Range A + Radio horizon A + Radio Horizon B +Range B
Chapter 2 contains background material that was used for establishing co-frequency and adjacent frequency separation distances to prevent harmful interference. The most generic model, as shown on this slide, shows the occurrence of interference that can be caused by aircraft transmission from aircraft “b”, and which can be received by aircraft “a”. The free space attenuation along the path between aircraft “b” and aircraft “a” should be sufficient to reduce the (undesired) signal level at aircraft a to at least 20 dB below the (desired) signal level received by aircraft b from transmissions of ground station A.
To achieve the 20 dB protection aircraft “b” should be well below the radio horizon of aircraft “a”. However, Annex 10 specifies that separation distances to the respective radio horizon of both aircraft “a” and aircraft “b” would be acceptable with the recognition that it is statistically unlikely that the two aircraft will be at the edge and maximum height of the coverage are at the same time.

11. Handbook Volume II Frequency assignment planning
Chapter 2 (2)
Frequency assignment planning criteria for VHF air-ground communication systems
Interference model (co-frequency)
Aeronautical broadcast stations (ATIS, VOLMET)
Do not involve aircraft transmission
Separation distances are less
Interference model (adjacent frequency separation)
Same model as for co-frequency separation
Takes into account the attenuation of the undesired signal by the (aircraft) receiver
1st adjacent channel separation (25 kHz): 10 NM
Aeronautical broadcast stations such as VOLMET and ATIS do not involve aircraft transmissions and therefore we only need to consider the prevention of harmful interference from the undesired broadcast ground station into the aircraft receiver. However, when the same frequency is used for aeronautical broadcast transmissions and for air/ground communications, the minimum separation distance is as in the case where both stations provide air/ground communication services.
When establishing Frequency assignment planning criteria for adjacent frequencies, we follow the same principle as for co-frequency assignment criteria. However, in this case we also consider the filter characteristic or attenuation provided by the receiver for adjacent frequencies, and as a result the adjacent frequency separation, the distances are significantly less, compared with co-frequency separation distances. For systems using 25 kHz frequency separation, the adjacent frequency separation (between aircraft) is 10 NM, although in most cases 3 NM would be sufficient.

12. Handbook Volume II Frequency assignment planning
Chapter 2 (3)
Frequency assignment planning criteria for VHF air-ground communication systems
Frequency separation and channelling
25 kHz and 8.33 kHz channel spacing.
Special consideration for mixed environment where both are applied
Designated Operational Coverage (DOC)
Table of uniform values for DOC
Complies with common values used in most Regions
Area services ACC-FIS – are in many cases not specified
Frequency separation and channeling - In accordance with the provisions in Annex 10 (Volume III and Volume V) frequency assignment planning criteria were developed for VHF communication systems operating with 25 kHz and with 8.33 kHz channel spacing.
Specific consideration was given to developing frequency assignment planning criteria in an environment where both 8.33 kHz and 25 kHz channel spacing is in operation. These criteria support the gradual implementation of 8.33 kHz channel spacing in Regions or areas, where required.
Current practice is that the designated operational coverage for air/ground communication systems is established from the regionally agreed table of uniform values for the designated operational coverage. To support this practice, the handbook has incorporated these tables. It should be noted though, that when using modern computer software for the frequency assignment planning, the software can easily accommodate different values for DOC and provide not only for greater flexibility in frequency planning but also improve the efficiency of the frequency assignment plan.
It has been noted that although the current table of uniform values for DOC do only specify the designated operational height of these services, the coverage of these services of course depends on the specific ACC or FIS area, which in many cases is not identified. Identification of the areas for these services is strongly recommended.

13. Handbook Volume II Frequency assignment planning
Chapter 2 (4)
Frequency assignment planning criteria for VHF air-ground communication systems
Calculation of separation distances.
Methodology for establishing separation distances
Air/ground communications
Aeronautical broadcast communications
Aerodrome surface communications
For each of these types the Handbook clarifies the principles and method used when the separation distances were established. A summary of the results (25 kHz channel spacing) is on the next slide
Based on the agreed general principles for establishing frequency assignment planning criteria for VHF air/ground communication systems, Volume II of the Handbook provides the relevant background that was used in developing the separation distances for different types of services.

14. Handbook Volume II Frequency assignment planning
Chapter 2 (5)
Frequency assignment planning criteria for VHF air-ground communication systems
VICTIM
Service
TWR
25/4000
AFIS AS
Surface
APP-U
150/450
APP- I
75/250
APP-L
50/120
ACC-U
Area/450
ACC-L
Area/250
FIS-U
FIS- L
VOLMET
260/450
ATIS
200/450
INTERFER
156
338
273
212
(Note 2) 25
520
455
394
APP-I
390
329
325
268
(Note 1)
FIS-L 15
This slide shows a summary of the calculated separation distances.

15. Handbook Volume II Frequency assignment planning
Chapter 2 (6)
Frequency assignment planning criteria for VHF air-ground communication systems
Frequency planning criteria for VDL were considered by the ACP between 2002 – 2008
Same methodology as for developing planning criteria for VHF voice systems
Criteria for VDL (Mode 2 and Mode 4):
The Handbook contains specific considerations to be taken into account when using VDL on the surface of an airport.
Frequency assignment planning criteria for implementing VHF Digital Link Mode 2 and Mode 4 were considered by the ACP in the period from 2002 – The result of this work is briefly presented in the Handbook. Detailed reports on the methodology that was used in establishing these criteria are available on the ACP website.
Interference source
DSB-AM
VDL 2
VDL 4
Victim 1 2

16. Handbook Volume II Frequency assignment planning
Future work
Future work will concentrate on developing harmonized and updated planning criteria for aeronautical radionavigation systems
The Handbook and other relevant material can be downloaded from the ACP website (Repository section) at
Future work on the Handbook Volume II will address the incorporation of globally harmonized frequency assignment planning criteria for aeronautical communication and navigation systems as follows:
NDB
ILS (Localizer, Glide Path)
VOR
DME
MLS
UAS or RPAS
HF air/ground communications
And finally, the Handbook and any other material is available on the ACP Website.