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/International Civil Aviation Organization
WORKING PAPER / ACP/WGF 21/WP 20
09/12/09
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
21ST MEETING OF THE WORKING GROUP F
Bangkok, Thailand, 10 – 18 December 2009
Agenda Item 4:Global Spectrum Requirements for ATM under AI 1.7: Summary of ITU WP4C Contributions
Presented by Tony Azzarelli (European Space Agency),
SUMMARYThis document exposes different contributions to the WP4C meetings that discuss long-term AMS(R)S spectrum requirements under AI 1.7. The list of documents are provided and also a reference to the working document towards a draft ITU report is given (i.e. WP4C Chairman’s Report Document 338 Annex 9).
The results of all studies are indicating that global spectrum requirements will be likely less than the one shown here the conclusion of this study is that the long-term spectrum needs for ATM will be less than the existing 2 x 10 MHz available today in the 1.5/1.6 GHz bands identified under footnote 5.357A.
ACTION
The ACP WG-F is invited to discuss this input contribution and propose to make a contribution to the next ITU WP-4C meeting March 2009 possibly making a conclusion that the long-term spectrum needs of aviation under AI 1.7 will be less than the 2 x 10MHz available today in the 1.5/1.6 GHz band.
In particular, studies have shown that the worst case global requirements, which take into account many different number of systems with worst case characteristics, will be (see ESA study Doc. 333) less than 4.2 MHz in the F/L and 1.6 MHz in the R/L.
1. Background
This document reports the work undertaken at the ITU WP4C regarding the long-term AMS(R)S spectrum estimations done and submitted by different Administrations at the WP4C meetings in 2009, i.e.:
4C/245 (Annex 15) Chairman’s Report of previous meeting
4C/215 from Egypt
4C/239 from the United Arab Emirates
4C/279 from Brazil
4C/318 from Japan
4C/326 from UK
4C/332 from ESA
4C/333 from ESA (Global Requirements)
4C/334 from Germany/ESA (European Requirements)
At the last WP4C meeting (August 2009), these contributions were compiled into one single reference document, which is at the moment a working document toward an Draft ITU-R Report on long-term AMS(R)S spectrum requirements. This document is now in the ITU WP4C Chairman’s Report Document 338 Attachment 9.
The results on spectrum requirements of these documents are included in the following summary Table 1, which is at the moment in the Doc. 338 Attachment 9.
The table also shows the different assumptions made from each study and we will go in some details in the next section.
The first thing to note that some studies aimed at calculation in a small airspace region, e.g. Europe, Middle-East and Brazil, while others attempted study spectrum requirements at a global level.
Secondly it is to be noted that the ITU WP4C has stopped any work to develop an ITU-R Recommendation on a methodology to calculate spectrum requirements. This was done because of objections by some Administrations on the methodology, and discussions were delaying work on the other aspects of the work of the AI 1.7 (e.g. CPM text and the studies themselves).
Table 1 : Results and Conclusions of several WP4C documents
(MHz)
comments / Forward-Link (1.5 GHz) / Return-Link (1.6 GHz)
1. Europe
Doc.4C/334: ESA / - Eurocontrol air traffic growth
- COCR V2
- 6 beam satellite system
- Simulations
- Worst case / unicast
parametric
- (a,b,g) / 3.3 MHz
-(1.2, 0.81, 1.1) / 1.3 MHz
-(1.3, 1.25, 1.1)
multicast AOC
parametric
- (a,b,g) / 2.1 MHz
-(1.2, 0.81, 1.1) / AOC not possible in multicast
2. Europe
Doc.4C/326: UK / - ESA estimated PIAC;
- COCR V2;
- Inmarsat 4 system;
- Calculations/ Simulations
case1: 100% satellite
case2: TMA 20% satellite,
ENR+ORP 100% satellite
case 3: same as case 2 + different aviation antennas / unicast
parametric
- (a,b,g) / [2.7 MHz]
-(1.19, 0.93, 1.39) / [0.235 MHz]
-(1.19,0.93,1.39)
multicast
- case 1
- case 2
- case 3 / [0.451 MHz]
[0.317 MHz]
[0.191 MHz] / [0.235 MHz]
[0.172 MHz]
[0.106 MHz]
3. Brazil
Doc.4C/279: Brazil / - COCR V2;
- Calculations. / 0.648 MHz / 0.715 MHz
4. Middle-EAST/Africa Doc.4C/215: Egypt / - Calculations of Capacity;
- Not COCR; / Is being updated for the next WP4C meeting / [3.118 MHz] / [1.730 MHz]
5. World-Wide Oceanic
Doc. 4C/239: UAE / - Assumed existing Inmarsat system ;
- Not using COCR;
- Only for oceanic communications. / Assumes an old work from 1999. / 1.080 MHz / not done
6. World-Wide
ESA study Doc.4C/333: ESA / - Eurocontrol air traffic growth and other data;
- COCR V2;
- Simulations;
- Different satellite systems;
- TMA, ENR, ORP
- Worst case / unicast
- 9 airspaces
- 18 airspaces
(a,b,g) / 4.8 MHz
4.2 MHz
(1.2, 0.81, 1.1) / 1.8 MHz
1.6 MHz
(1.3, 1.25, 1.1)
multicast AOC
- 9 airspaces
- 18 airspaces
(a,b,g) / 3.0 MHz
2.6 MHz
(1.2, 0.81, 1.1) / not possible in multicast
7. World-Wide
Japan Study Doc.4C/318: Japan / - MTSAT satellite;
- Conventional aviation communications, Not using COCR;
- PIAC approach. / Global beams
- 2 networks
- 3 networks / 1.275 MHz
2.231 MHz / not done
Spot beams
- 2 networks / 2.188 MHz / not done
Beam Cluster
3 networks
- case 3
- case 4
- case 5 / 2.428 MHz
3.281 MHz
4.069 MHz / not done
unicast = point-to-point communications
multicast = point-to-multipoint communications
2. Discussions on Each Document
We will divide the discussion as given below, i.e. between (1) the regional satellite system spectrum requirements versus (2) the global spectrum requirements from an AMS(R)S allocation perspective.
2.1 Regional Spectrum Requirements
The studies given in Table 1 above which refer to regional satellite systems are in rows 1 (Europe - ESA study), 2 (Europe – UK study), 3 (Brazil airspace – Brazil study) and 4 (Middle-East – Egypt study).
2.1.1 ESA study Doc. WP4C/334
The ESA study results over an European airspace are given below in Table 2. These were extracted from the above Table 1.
ESA developed this study based on a 6 satellite beam solution to cover the European airspace. In terms of the future aviation communications needs, ESA assumed:
- COCR V2 communications requirements on latency and data bandwidth;
- Air traffic based on Eurocontrol estimated long-term growth for year 2025 and busiest day of the year;
- Air traffic domains TMA, ENR and ORP.
The method of calculation of the spectrum requirements was based on a parametric approach on the communication link, i.e. based on (a, b, g) parameters which have been detailed in previous ICAO WGF meeting and the ICAO input document to the ITU WP4C meeting on the methodology.
The ESA paper details quite deeply the calculation of the spectrum requirements starting from the required information volume (RIV) determined by simulations of flights and COCR V2 communications.
In the forward –link ESA also made two different calculations whereby certain high data AOC messages (e.g. WXGRAPH) could be transmitted in a multicast (i.e. point-to-multipoint) communication mode instead of unicast as defined in the COCR V2 document. This reduced the AOC spectrum needs by about 75%.
In general we should bear in mind that that AOC multimode or broadcast mode operations are not specified in the COCR V2, however it could potentially be a solution that could use resources in a more efficient way. The aviation community will have to investigate if this is feasible (we have also raised this at the last WGF meeting).
The Table 1 also provide the satellite system parametric characteristics (a, b, g) which are dependent on the satellite system parameters.
As a result the European long-term (about year 2025) spectrum needs are reports in Table 2 below, i.e.:
- Forward-link: 3.3 MHz in unicast and 2.1 MHz in multicast mode;
- Return-link: 1.3 MHz.
Fig. 1: European airspace with potential 6 beam satellite coverage
Airspace / Assumptions / Spectrum requirements(MHz)
comments / Forward-Link (1.5 GHz) / Return-Link (1.6 GHz)
Europe
Doc.4C/334: ESA / - Eurocontrol air traffic growth
- COCR V2
- 6 beam satellite system
- Simulations
- Worst case
- TMA, ENR, ORP / unicast
parametric
- (a,b,g) / 3.3 MHz
-(1.2, 0.81, 1.1) / 1.3 MHz
-(1.3, 0.81, 1.1)
multicast AOC
parametric
- (a,b,g) / 2.1 MHz
-(1.2, 0.81, 1.1) / AOC messages not possible in multicast
Table 2: European Spectrum Requirements – ESA Doc. WP4C/334
2.1.2 UK study Doc. 4C/326
The UK study is based on an Inmarsat-4 satellite system coverage of the European Airspace (see Fig. 2 below).
The UK analysis then uses the parametric method based on the factors (a, b, g) as defined and used in the ESA study, and adopting the Inm-4 system characteristics to calculate these parameters. It then used the information volume estimations of the ESA study of Doc. 333 to determine the European spectrum requirements through an Inmarsat system.
The UK study shows that the AMS(R )S requirements are well within the 2 x 10 MHz of spectrum available.
Below on Table 3 we have the UK results.
Unicast Assumptions
In the unicast mode the UK results are:
- 100% satellite mode:
o UK Results:
§ Forward Link 2.7 MHz
§ Return Link 0.235 MHz
Multicast Assumptions
Like the ESA study the UK study also considers a Multicast assumption, where certain COCR services are assumed to be transmitted in a point-to-multipoint mode (also could be referred to as Broadcast mode).
In the multicast mode of operation the UK identified three cases:
- Case 1: Assuming 100% satellite operations for TMA, ENR and ORP
- Case 2: Assuming that for TMA with 20% satellite communications, 100% satellite coverage for ENR and ORP.
- Case 3: Assumes the same as Case 2 and also it assumes AES enhancement, e.g. with the use of low gain and intermediate gain antennas.
The current results of the UK study are given in Table 3 below.
The results of the UK study can be extrapolated globally using the same satellite network and assuming also a 4 colour frequency reuse pattern.
The conclusions from the UK study are that the long-term AMS(R)S requirements fit well within the existing 2 x 10 MHz available frequencies in 1.5/1.6 GHz MSS band.
Fig. 2: European spot beam coverage and elevation contours for Inm-4 satellite at 25º E
Airspace / Assumptions / Spectrum requirements(MHz)
comments / Forward-Link (1.5 GHz) / Return-Link (1.6 GHz)
2. Europe
Doc.4C/326: UK / - ESA estimated PIAC;
- COCR V2;
- Inmarsat 4 system;
- Calculations/ Simulations
case1: 100% satellite
case2: TMA 20% satellite, ENR+ORP 100% satellite
case 3: same as case 2 + different aviation antennas
Requires additional work / unicast
parametric
- (a,b,g) / 2.73 MHz
- (1.39,0.93, 1.19) / 0.235
- (1.39,0.93, 1.19)
multicast
- case 1
- case 2
- case 3 / 0.451 MHz
0.317 MHz
0.191 MHz / 0.235 MHz
0.172 MHz
0.106 MHz
Table 3: European Spectrum Requirements – UK Doc. WP4C/326
2.1.3 Brazil study Doc. 4C/279
In brief the Brazil study is based on the Brazilian airspace including South Atlantic Ocean airspace (see Fig. 3 below). This study is a thorough method on calculating the estimated spectrum requirement of a potential satellite system covering this airspace and using the COCR V2 services.
The results of this study are given below in Table 4.
Fig. 3: Area under the Brazilian Air Traffic Control Management
Airspace / Assumptions / Spectrum requirements(MHz)
comments / Forward-Link (1.5 GHz) / Return-Link
(1.6 GHz)
3. Brazil
Doc.4C/279: Brazil / - COCR V2;
- Calculations; / 0.648 MHz / 0.715 MHz
Table 3: Brazilian Spectrum Requirements – Brazil Doc. WP4C/279
2.1.4 Egypt study Doc. 4C/215
This document was presented by the Administration of Egypt at the April 2009 meeting. It was stated at the WP4C meeting that this is a preliminary study and Egypt will submit another document at the next WP4C meeting in March 2010.
The results of this preliminary study is given below in Table 5 below.
Airspace / Assumptions / Spectrum requirements (MHz)comments / Forward-Link (1.5 GHz) / Return-Link (1.6 GHz)
4. Middle-EAST/Africa Doc.4C/215: Egypt / - Calculations of Capacity;
- Not COCR.
Requires additional work / [3.118 MHz] / [1.730 MHz]
Table 5: Middle-East and Africa Spectrum Requirements – Egypt Doc. WP4C/215
2.2 Global Spectrum Requirements
The following two documents explicitly tackled the matter of long-term estimation of spectrum requirement from a global perspective.
2.2.1 ESA Doc. WP4C/333
Doc. WP4C 333 is a study from ESA based on simulation of flights at year 2025 for the busiest day of the year and at the busiest period of the day. This is done for the region shown in Fig.4 below covered by 18 different beams or cluster of beams which are provided by different satellite systems. This could be considered as a worst-case case study.
In summary, this states that the long-term aviation spectrum needs (after 2025) at a global level are in the worst case:
- Unicast:
Large beams: 4.8 MHz F/L – 1.8 MHz R/L
Smaller beams: 4.2 MHz F/L – 1.6 MHz R/L
- Multicast for AOC F/L transmissions, No change in R/L
Large beams: 3.0 MHz F/L – 1.8 MHz R/L
Smaller beams: 2.6 MHz F/L – 1.6 MHz R/L
As seen here the global spectrum results depend strongly on the characteristics of the satellite systems used and deployed in the airspace. The assumptions here are not based on real systems, but instead on a worst case scenario.
Hence, as spectrum requirements will be likely less than the one shown here the conclusion of this study is that the long-term spectrum needs for ATM will be less than the existing 2 x 10 MHz available today in the 1.5/1.6 GHz bands identified under footnote 5.357A.
Fig. 4A: Beams Reuse Scheme for the 9 Airspace Areas
(case Large Beams)
Fig. 4B: Beams Reuse Scheme for the 18 Airspace Areas