1
ACP-WGF22/WP-/
International Civil Aviation Organization
WORKING PAPER / ACP-WGF22/WP-7
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
TWENTY SECOND MEETING OF WORKING GROUP F
Mexico City, Mexico 21 – 30April 2010
Agenda Item 3: / Development of material for ITU-R meetingsSpectrum Requirements for surface applications at airports in the 5 GHz range
(Presented by Mike Biggs)
SUMMARYTo accommodate future growth in surface applications, the 5 000-5 030 MHz band has been selected for evaluation as additional spectrum for the airport radio local area network (RLAN) currently being developed for operation in the 5091-5150 MHz band. This paper takes information regarding the spectrum requirements of planned 5 GHz surface applications at airports previously provided to the ITU, as updated by further work occurring in an aeronautical standardization body (RTCA Inc.), and incorporates it into a preliminary draft new report ITU-R M.[AMRS-5GHz] under development in Working Party 5B. The goal of the Report is to assess the spectrum requirement for such a system to determine whether the existing band (5091-5150 MHz) is sufficient, or whether additional spectrum (e.g., portions of 5000-5030 MHz) is required.
ACTION
The meeting is invited to, as necessary, further develop the material with the goal of providing an ICAO input to the May 2010 Working Party 5B meeting.
1. Introduction
To accommodate future growth in surface applications, the 5 000-5 030 MHz band has been selected for evaluation as additional spectrum for the airport radio local area network (RLAN) currently being developed for operation in the 5091-5150 MHz band. A study is currently underway in ITU-R Working Party 5B (WP5B)to address the spectrum requirement for such a system to determine whether the existing band (5091-5150 MHz) is sufficient, or whether additional spectrum (e.g., portions of 5000-5030 MHz) is required. The results will be incorporated in a preliminary draft new report ITU-R M.[AMRS-5GHz].
2. Background
2.12007 World Radiocommunication Conference (WRC-07) studies regarding its Agenda Item 1.6 resulted in Report ITU-R M.2120, providing an “Initial estimate of new aviation AM(R)S[1] spectrum requirements”. In that report, it was noted that there was a requirement for spectrum to support surface AM(R)S applications at airports including data links which were distinguished by a high data throughput, however only moderate transmission distances. The conclusion of that report was that “it is expected that the total aeronautical spectrum requirement for the surface domain will be on the order of 60-100 MHz”.
2.2Follow-on work under WRC-12 Agenda Item 1.4 refined those studies, and the results are being captured in a new Report under development by WP5B entitled “Spectrum requirements for surface applications at airports in the 5 GHz range“. Initial inputs to that Report were based on a study performed by the United States and presented to the October 2008 meeting of WP5B, (see document 5B/130).
2.3Since that meeting receiver/system performance requirements activities for the airport surface network (previously known as ANLE, currently termed as AeroMACS) have begun within RTCA, Inc and the European Organization for Civil Aviation Equipment (EUROCAE), and planning has begun for an International Civil Aviation Organization (ICAO) technical working group to develop standards (ACP WG-S). These new efforts have introduced additional applications for the AeroMACS beyond those presented in the October 2008 study. Some of the new applications that have been identified, and the resultant data requirements[2], are outlined below.
–Providing a means to load airport mapping database (AMDB) data onto the aircraft. This data, based on ARINC specification 816, provides updated aerodrome information during Aeronautical Information Regulation and Control (AIRAC) cycles. The required data throughput for this application is pre-computed and encoded in Binary-XML with an average file size, after compression, of 825,000 Bytes (825 kB) per airport. Typically 1/3 of the airports in a data set are updated during an AIRAC cycle. This data is assumed uploaded within 15 minutes for Phase 1, 10 minutes for Phase 2. Therefore assuming a total data set of 300 airports, the no overhead data rate for Phase 1 is 733 kbps (825kB * 8*(300/3)/(15*60)) and 1.1Mbps for Phase 2 (792 kbps and 1.2 Mbps respectively with overhead). 5 and 7 simultaneous uploads to aircraft are assumed for Phase 1 and 2 respectively.
–Providing a means to download integrated vehicle health management (IVHM) data from the aircraft when it is on the airport surface. This system will be used to detect and monitor the health of critical aircraft systems. Information on current efforts on this topic can be found at: Data is categorized in terms of required latency (real-time, near-real time, and delayed). For this study two components make up the required throughput (a) the real-time requirements for the aircraft on the runway/taxiway/ramp, and (b) the near real-time/delayed data that is stored on-board during the flight and off-loaded during taxi and in the gate area during the aircraft turn-around period. The estimate for component (a) 33.9 to 303.4 kbps (with overhead) times 48 aircraft for Phase 1 and 70 for Phase 2. To provide an estimate of minimum requirements, it is assumed that 10% of the aircraft are operating at the maximum data rate, while the remaining 90% are operating at the minimum data rate. This results in an aggregate real-time IVHM download rate of 2.98 Mbps for Phase 1 and 4.26 Mbps for Phase 2. For component (b) data is accumulated during flight at a rate of 5.7 to 483.2 kbps (no overhead). Assuming a 2 hour flight, an 8 minute taxi and a (Phase 1) 54 min aircraft turn-around, the maximum download data rate is (483.2*120*60) ÷ (62*60) = 0.94 Mbps. Assuming a 2 hour flight, 8 minute taxi and a (Phase 2) 36 min aircraft turn-around, the maximum download data rate is (483.2*120*60) ÷ (44*60) = 1.32 Mbps. In order again to provide an estimate of minimum requirements, it is assumed that an aircraft is storing data at the maximum rate for 10% of the flight time, and at the minimum rate for 90% of the flight time. Under these assumptions the minimum per-aircraft download rate (with overhead) is 111.8 kbps for Phase 1 and 157.5 kbps for Phase 2. It is assumed there are 154 aircraft in the gate and taxiway area for Phase 1 and 222 for Phase 2 concurrently downloading stored IVHM data.
–Providing 4-dimensional weather data to aircraft tailored to their particular flight route. This capability, under development within the United States NexGen program, will provide aircraft with predicted weather, along their planned route, for the time they expect to reach that geographic area (i.e., the weather shown for location X would be for when the aircraft is going to be a location X, not for the current time) by integrating multiple information sources maintained at different locations that are independently managed by various agencies. As a result, each aircraft would receive its own 4D weather data. The required aggregate data throughput (no overhead) for this application[3] is 1.9 Mbps for Phase 1 and 4.12 Mbps for Phase 2. In addition, ITWS products for the departure airport would be common to all aircraft and as such would be provided via broadcast. The average data rate for that product is 0.29 Mbps (without overhead).
–Providing necessary data to support aircraft de-icing operations. This can include 2-way communications between the aircraft and de-icing facility, sensor monitoring, and real-time video to ensure complete coverage. The required data throughput for this application is 281.9 kbps per de-icing facility, and 2 facilities are assumed.
–Providing resources to support operation of unmanned aircraft systems (UAS) on the airport surface. Such resources, not accounted for in current studies performed as part of WRC-12 agenda item 1.3 (AI1.3), could include: multi-camera real-time video to support aircraft taxi and ramp operations, and communications/control data to overcome limitations due to building blockages/shadowing on the airport surface not accounted for in the AI1.3 studies. Document 5B/337 suggests for the taxi phase of flight each unmanned aircraft may require 3 cameras each streaming real-time video. Bit rate for such video (before overhead) is estimated at 281.9 kbps per camera (including overhead), and 5 UAS are assumed for Phase 1; 7 for Phase 2.
2.4As a result, Attachment 1 provides modifications to the initial material for PDNR ITU-R M.[AMRS-5GHz] to reflect the current status of the spectrum requirements studies, shown as “track changes” to the version contained in Annex 24 of the November 2009 WP5B Chairman’s Report (5B/417 Annex 24). As work progresses it is expected that additional applications for the AeroMACS network will be developed, which may result in additional spectrum requirements.
3.0References
1. C. Pschierer and J. Schiefele, Open Standards for Airport Databases – ARINC 816, IEEE DASC, 2007
2. R. Kerczewski, Off-Board Communications for Vehicle Health Management, NASA presentation to ICAO ACP WG-F, December 2009
3. Four-Dimensional Weather Functional Requirements for NextGen Air Traffic Management, JPDO Weather Functional Requirements Study Team, Version 0.1, January 2008
4. Communications Operating Concept and Requirements for the Future Radio System (COCR v2.0), 2007
5. ITU, Characteristics of unmanned aircraft systems (UAS) and spectrum requirements to support their safe operation in non-segregated airspace, December 2009, Document 5/177E
6. ITU, Data Rate Validation Study for UAS Video Transmissions , November 2009, Document 5B/337E
7. G. Livack, Meteorological (MET) & Aeronautical Information Services (AIS) Data Link Services and Applications, November 3, 2009, RTCA SC-206 EUROCAE WG-76 Presentation to RTCA SC-223
8. R. Kerczewski, Off-Board Communications for Vehicle Health Management - Estimate of Off-Board Data Transmitted on Airport Surface, Feb. 2010
9. Jeppesen Aviation Weather for United States,
10. METAR Product Description, ver. 1.0, National Oceanic and Atmospheric Administration, Earth Systems Research Laboratory / Global Systems Division, Boulder, Colorado
11. NextGen Data models for ITWS, rev. 1.0, Lincoln Laboratory, Massachusetts Institute of Technology, Nov. 2009
12. SC-186 Aerodrome Data Information Definition Task Final Report, December 2009
13. IEEE, IEEE Standard for Local and Metropolitan Area Networks, Part 16: Air Interface for Broadband Wireless Access Systems, IEEE Std 802.16-2009, 29 May 2009
14.I. Gheorghisor, Spectral Requirements of ANLE Networks for the Airport Surface, MP080109R1, July 2008
ATTACHMENT 1: Annex 24 to Working Party 5B Chairman’s Report
Preliminary Draft New Report ITURM.[AMRS-5GHz]
Spectrum requirements for surface applications at airports in the 5 GHz range
[Framework for PDNR ITURM.[AMRS-5GHz]:
1)No modifications to Report ITURM. 2120. This Report will not be suppressed.
2)Include appropriate elements of PDRReport ITURM.2120 relating to 5 GHz band into the DNR ITURM.[AMRS-5GHz].
3)PDNReport ITURM.[AMRS-5GHz] will be finalized at 5B May 2010 with the view of upgrading the status to DNR and subsequent submission to SG 5 for approval.
4)The new Report should not contradict existing Report ITURM.2120. This to be ensured when new Report is established.
5)The issue of AM(R)S allocation requirements will be addressed in draft CPM Report.]
Editor’s Note: It is expected that this Framework material will be deleted in the final DNR M.[AMRS-5GHZ]
1.Introduction
Aeronautical applications supporting surface applications at airports – including data links – are distinguished by a high data throughput but only moderate transmission distances, and it is expected that a single resource can be shared at multiple geographic locations. The system to support such applications will be implemented in some portion of the 5000-5150MHz band.
Administrations and the International Civil Aviation Organization (ICAO) performed studies in order to determine the amount of spectrum needed for each aeronautical airport surface applications in the 5 GHz frequency bandrange. The results, while preliminary, provide an order of magnitude of expected spectrum requirements and further the work begun in Report ITURM.2120. The results of expected spectrum requirements, irrespective of any reference to a given service, in the 5GHz range are incorporated in this [draft] Report.
2Airport surface communications
Estimates Initially estimates for surface spectrum requirements were determined using throughput estimates based on a review of current surface communication requirements, limited to those supporting safety and regularity of flight, at a major airport[4] in the United States. Those estimates were then augmented by new applications for the airport surface network that have arisen during its performance requirements/standardization activities. Those total throughput requirements were then assumed satisfied using the candidate surface system technology (based on the Institute of Electrical and Electronics Engineers (IEEE) Standard IEEE 802.16e), and an overall spectrum requirement was derived.
The International Civil Aviation Organization (ICAO) has identified a system based on the IEEE802.16e standard, which specifies the air interface for broadband wireless access (BWA) systems, including mobile subscribers moving at vehicular speeds. The standard is also flexible in that it can be implemented in bands below 10GHz and with channel bandwidths from 1.25MHz to 20MHz. The approach followed for the spectrum requirements study involved:
1)cataloguing the potential message traffic for the airport network. For this study two implementation phases were assumed: up to 2020 (Phase 1) and beyond 2020 (Phase 2);
2)determining the airport data rate (bits/sec) requirement to satisfy that message traffic;
3)developing assumptions on the distribution of network participants[5]. In order to minimize total spectrum required the assumption is made that the airport network infrastructure is installed to ensure use of higher modulation and coding schemes (i.e., 16-QAM 3/4 and above) everywhere in the gate/ramp areas and for all Category 2 applications;
4)developing assumptions on the network channel structure (for this analysis, channel bandwidths of 10 and 20MHz were considered) and channel loading;
5)estimating spectrum requirements based on the above assumptions.
Tables1, and 2 and 3 contain the estimated spectrum requirements for an airport surface network at a major airport supporting the assumed applications. Table1 addresses only airport surface communications between aeronautical stations and aircraft stations (Category 1[6]). Table2 addresses other (Category2) airport surface communications not covered by Table1. Table3 2 includes total requirements in Tables1 and 2. In all of these cases however, the assumed communications were limited to those supporting safety and regularity of flight. As previously mentioned, two different channel bandwidths (10MHz and 20MHz) were considered. For the 20MHz bandwidth case omnidirectional antennas were assumed for the base stations, while for the 10MHz case sectorized (threesectors per base station) antennas were assumed. The calculation of the airport data rate requirement (item2 above) is detailed in Annex1.
Editorial Note: Views were expressed that the split of spectrum requirements into the three tablesmay not be required. Existing Table2 may, therefore, be suppressed at a later stage.
Table1
Category 1: Airport surface communication requirements between
aeronautical stations and aircraft stations (*)
Maximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz) / Maximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz)
Phase 1 (2020) / 8.338.9 / 2060 / 14.544.4 / 3060
Phase 2 (post 2020) / 19.677.8 / 4080 / 25.883.3 / 5090
(*)These values are estimated based on specific parameters and assumptions. Further study discussed below could serve to increase or decrease these estimates.
[Table2
Category 2: Airport surface communication requirements not covered by Table1(*)
Implementation phase / Channel BW = 20MHz / Channel BW = 10MHzMaximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz) / Maximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz)
Phase 1 (2020) / TBD / TBD / TBD / TBD
Phase 2 (post 2020) / TBD / TBD / TBD / TBD
(*)These values are estimated based on specific parameters and assumptions. Further study discussed below could serve to increase or decrease these estimates.
]
Table32
Overall airport surface communication requirements(*)
Implementation phase / Channel BW = 20MHz / Channel BW = 10MHzMaximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz) / Maximum estimated data rate (Mbps) for a large airport / Estimated spectrum requirements (MHz)
Phase 1 (2020) / 60.891.4 / 100100 / 6796.9 / 100100
Phase 2 (post 2020) / 72.1130.3 / 120120 / 78.3135.8 / 110130
(*)These values are estimated based on specific parameters and assumptions. Further study discussed below could serve to increase or decrease these estimates.
3Discussion
Certain observations should be made on the estimates in Tables1 to 3and 2 and should be further investigated, if necessary:
–Refining the assumption that all the subscriber stations are uniformly distributed over the airport surface, as well as taking advantage of advanced features of the 802.16e standard such as “smart” antennas, may serve to reduce the required spectrum. Care must be taken however to ensure that the use of any such enhancements does not impact compatibility with other services using the bands. For example, the addition of multiple base stations on an airport, base stations with sectorized antennas, and/or the use of directional antennas for certain high data rate user applications could raise the available carrier-to-noise (C/N), facilitating the use of higher-rate modulations and reduced spectrum requirements. Such use might also reduce compatibility with other users of the spectrum which, in turn, may reduce the number of airports at which a given portion of spectrum is available. This could impact the overall spectrum requirements.
–The surface network spectrum requirements are scenario-dependent, however the methodology utilized for this study could be applied to other aviation scenarios as well. Inparticular, detailed analyses are needed to determine data traffic at airports and to determine the impact of sectorized antennas on fulfilling those traffic requirements.
–The impact of the channel loading factor should be analysed in detail. The value of 0.75 used for this study is fairly ambitious and needs verification, through modelling and simulation, by using traffic models for the aeronautical applications. It is unlikely that it would move in any direction other than down, and it should be noted that using a lower value could serve to increase the amount of spectrum required.
–While header compression was not assumed for this analysis, and in the end state header compression may reduce spectrum required, such reduction may be small and would not change the overall conclusion, if that is the case.
–The broadcast/multicast features of the IEEE 802.16e standard should be further explored, however it is anticipated that they would require a more complicated frame structure which could increase the overhead, so it is not expected to reduce overall spectrum requirements.