Status and review of the emerging satellite communication ...
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
Working Group C – 6th meeting
Toulouse, France
20 – 24 October 2003
Agenda items 6: Evaluation of potential technologies
Status and review of the emerging satellite communication technologies
Presented by Philippe Renaud
Prepared by Phil Platt
SUMMARY
This working paper provides an overview of satellite communication technologies that are being used to support communication with aircraft or are under development. The information in the paper is based on the best available information available to the author – comments and corrections are welcome.
Background
Some airlines have invested heavily in the current Aeronautical Mobile Satellite Service (AMSS) and it is being used on a proportion of these aircraft for ATC purposes. However, other satellite systems are being fitted to aircraft for a range of purposes.
This paper gives a high level overview of the all satellite systems, their status and planned usage, and gives a subjective appraisal of their potential use to support safety communications. The information in the paper is based on the best available information available to the author – comments and corrections are welcome.
Satellite Systems
1 Inmarsat Systems
The current ICAO AMSS is compatible with the ‘classical’ Inmarsat systems namely Aero H, H+, I and L and these contain specific provisions to support safety (AMS(R)S) and non-safety communications. They operate in the L-Band and are currently the only systems that are recognised to carry aeronautical safety communications.
Initial deployment was based on the Aero H/H+ high gain antenna systems for voice and data services. Later the Aero I intermediate gain systems were introduced with a cheaper antenna for service in spot beam, and also the data only low cost Aero L ( the most notable use is for helicopter safety in the Norway area of the North Sea).
The deployment of AMSS has never reached the levels originally predicted with around 3000 aircraft equipped today; these are mainly long haul aircraft. Around 1200 of these are FANS1/A equipped for ATM use in various regions of the world - mainly remote or oceanic – where the applications and associated benefits are met by the end-to-end performance of the implemented system. FANS1/A is based on ACARS messaging techniques and consequently the performance is largely determined by the efficiency of the end-to-end network of which the satellite link is only a part.
In 2002 Inmarsat introduced a new aeronautical communication system called Swift64 which reuses the existing Aero H installation on an aircraft and offers high-speed data service – 64 kbps - for non-safety use. Swift64 shares some of the components of an existing Aero H installation e.g. the HPA and antenna to provide the new ISDN or data packet data services.
In the future another product BGAN (Broadband Global Area Network) can offer high data rates (432kb/s) in spot beams. Again this service is believed to be aimed at non-safety uses.
Regional BGAN (RBGAN) is an initial implementation of the BGAN service and uses the existing Thuraya satellite network which provides a high speed data service covering large parts of west and eastern Europe, Africa and the Middle East. This service does not appear to be used by aviation.
2 Connexion by Boeing®
Connexion by Boeing provides high-speed, two-way Internet-based connectivity to aircraft in flight and is designed to support two market segments: commercial aircraft operators and their passengers as well as executive aircraft, including operators of private and government executive jets. Connexion was one of the main candidate systems as for a Next Generation Satellite System (NGSS) under discussion in AMCP WG-A. However it is believed that there has been no further consideration of Connexion to support safety communications.
WRC 03 agreed to extend the secondary mobile satellite service allocation in the 14-14.5 GHz band to include the aeronautical mobile satellite service allowing Connexion by Boeing and other satellite-based services into the global communications market for non-safety communications.
The Connexion by Boeing system comprises -
• Airborne system: airborne antennas, airborne servers, routers, and associated wiring. Boeing has developed a proprietary solid-state phased array receive and transmit antenna.
• Ground system: network operations centre, associated satellite uplink and downlink equipment, and business operation centre.
• Space system: leased satellite transponders. Arrangements have been made with a number of satellite service providers including Intelsat, Eutelsat, etc.
Connexion by Boeing is obtaining relevant authorisations from the national regulatory agencies in those countries where the system operates including the civil aviation authorities responsible for aircraft offering the service.
Lufthansa, British Airways, SAS and All-Nippon Airways, have equipped, or are going to equip with Connexion by Boeing.
3 Iridium
The Iridium system was another of the main candidate systems to be considered as an NGSS under discussion in WG-A.
The original Iridium company went bankrupt and an organisation with less ambitious goals is now offering a commercial service. Iridium currently provides services to the United States Department of Defense and launched commercial services worldwide in March 2001.
The Iridium Satellite System is the only provider of truly global voice and data capability with complete coverage of the Earth (including oceans, airways and Polar regions). The Iridium constellation comprises 66 low-earth orbiting (LEO) satellites operated by Boeing. Iridium suggests that its service ‘is ideally suited for industrial applications such as heavy construction, defense/military, emergency services, maritime, mining, forestry, oil and gas and aviation’.
The FAA is using Iridium to complement the UAT coverage system in Alaska CAPSTONE ADS-B project. It is believed that avionics manufacturers are developing products to support ATS applications.
4 Globalstar
The Globalstar constellation consists of 48 Low-Earth Orbiting (LEO) satellites providing coverage of over 80% of the Earth's surface, (excluding the extreme Polar Regions and some mid-ocean regions). The satellites are placed in eight orbital planes of six satellites each, inclined at 52 degrees to provide service on Earth from 70 degrees North latitude to 70 degrees South latitude.
The satellites utilise "bent pipe" architecture and a user’s signal will be received by several satellites and retransmitted via CDMA to a satellite dish at the appropriate ground Gateway where the call is then routed locally through the terrestrial telecommunications infrastructure.
This system appears to be targeted mainly at General Aviation however it should be noted that avionics is available that complies with the RTCA NGSS MOPS. ARNAVSystem Inc has developed a fully qualified (FAA and FCC) voice and data capable aviation product the RCOM-100, which is capable of providing either circuit switched data or packet data at 9.6 kbps throughput.
Safety versus Non-safety usage
Other than the Inmarsat Aero H, H+, I and L systems, none of the above systems was specifically designed to carry safety-related communications nor are they currently defined in ICAO SARPs.
The original Iridium company was committed to put in place the extra provisions in their network to achieve the required level of service to carry safety communications. Initial technical provisions were being considered in AMCP WG-A. This work was halted when the company became bankrupt.
Connexion by Boeing was also being considered as an NGSS by WG-A and some initial material for a Technical Manual was being developed.
Now several years later, it is understood that none of the proponents of these non-safety systems is intending to offer the systems for safety communications however the need to support safety communications may become more attractive given the right economic environment.
So what would it take to make these systems suitable for safety communications ? The following issues need to be considered -
• Appropriate RF band – is the system operating in a designated AMS(R)S band?
• Priority – do safety communications get priority over non-safety traffic ?
• Certification to correct level – are the avionics certified to the appropriate level, typically Level C software? Is the Ground Earth Station software developed to the appropriate standards ?
• Provisions to offer correct QoS – are the satellite service providers willing to offer an appropriate guaranteed level of service ? Have they put in place appropriate network monitoring and control facilities ? Have they carried out an appropriate safety case analysis ?
• Are the appropriate international standards in place ?
If no specific provisions to handle safety communications have been put in place does this mean that it cannot support safety communications ? It is suggested that the answer may not automatically be no and has to considered on a case-by-case basis. For example, suitable mitigation measures may be able to be put in place to overcome any risks or it may be possible to modify the existing systems to better meet safety requirements.
Conclusions
The Working Group is requested to the note the information in this paper.
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