INFORMATION PAPER / ACP-WGF14/IP-3
23/8/05
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
FOURTEENTH MEETING OF WORKING GROUP F
Malmo, Sweden 22 – 26 August 2005
WRC 07 Agenda Item 1.5 and 1.6 – Civil Aeronautical Security Requirements
(Eurocontrol Agency)
SUMMARYThis contribution addresses the need for radio spectrum for aeronautical security and associated telemetry and telecommand. It updates the paper previously presented in to CEPT in December 2004 noting the comments received and some preference of some radio regulators for Europe to allocate the majority of security requirements under an AMS allocation rather than an AM(R)S allocation. However, the current definition of AM(R)S would encompass security requirements given that they include safety of life and flight regularity applications.
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ACTION
The meeting is invited to consider this paper which is being input to the CEPT PT3 process next week by the Eurocontrol Agency and provide any comments back to the Eurocontrol Agency.
/ Doc. ECC/CPG07/PT3/XXX(04)057
CPG07/PT3-3
Copenhagen, 29 - 31 August 2005
Date issued: 15 July 200522 August 2005 29 November 2004
Source: Spectrum Frequency Consultation Group (submitted by Eurocontrol)
Subject: WRC 07 Agenda Item 1.5 and 1.6 – Civil Aeronautical Security Requirements and associated telemetry/telecontrol
Summary:
This paper is submitted by Eurocontrol on behalf of the European aviation Spectrum Frequency Consultation Group (SFCG). This assumes non sharing of this spectrum.
The paper addresses the need for radio spectrum for aeronautical security and associated telemetry and telecommand. It updates the paper previously presented in PT3 (04) in December 2004 noting the comments received and the preference of some radio regulators for Europe to allocate the majority of security requirements under an AMS allocation rather than an AM(R)S allocation. However, the current definition of AM(R)S would encompass security requirements given that they include safety of life and flight regularity applications.
This introduces a dilemma in that there is a provision for aeronautical security requirements to be incorporated under WRC AI 1.6 as AM(R)S but not as AMS. There is the alternative opportunity for it to be incorporated under aeronautical telecommand or high bit rate aeronautical telemetry under agenda item 1.5
It notes validation f
Flight trials using the adapted IMT-2000 standards and the bandwidth requirements have shown that aeronautical security systems can be realised in the band 5091-5150 MHz with a range of up to 90 nautical miles. Further flight trials of the new system isare planned in the first half of 2006.
In conclusion It concludes that:
· Aviation security needs to have radio spectrum.
· The requirement in the 5091-5150 MHz band does not necessarily preclude requirements in other aeronautical bands and as such if the requirements cannot be satisfied there, an allocation will be needed in another band.
· The 5 GHz band is highly suitable to the security applications, which are high information data rate and relatively low range.
· It has been demonstrated by flight trials that the adapted IMT-2000 TDD standards using CDMA technology isare suitable and this variant minimises spectrum requirements.
· Compatibility with other services is considered achievable but this will require further study.
· The bandwidth required is initially 15 MHz (bidirectional TDD) in the 5091-5150 MHz band5 GHz range.
1. It should be noted that the new aeronautical security system will provide additional functionality that can be used by the ANLE system, NATO and the state military and UAV’s, some of this functionality is AM(R)S and even ARNS.
Proposal:
TTo consider allocating bandwidth for aeronautical security in the band 5091-5150 MHz.
Background:
WRC 2007 Agenda Item 1.6 makes provision for allocating spectrum for new aeronautical security applications under AM(R)S.
WRC AI 1.5 is for allocating spectrum for Aeronautical telemetry.
1
INTRODUCTION
Among other things, Agenda Item 1.6 for the WRC-2007 addresses the use of the band 5091-5150 MHz for aviation systems and specifically includes security. The European Commission and Eurocontrol are co-funding a project called “Enhanced ATM Security for Europe’s Single Sky”.
During the ICAO High-Level Ministerial Conference on Aviation Security of 2002, Eurocontrol presented four strategic initiatives, namely to:
· Establish processes to optimise the sharing of Civil Air Traffic Control (ATC) and Military (ATC/Air Defence) radar information;
· Create a European Regional Focal Point for Air Traffic Management information, involving civil and military interests;
· Give priority to the validation of a high capacity air-ground communications capability for the transmission of encrypted cockpit voice, flight data and on-board video information;
· Ensure that both civil and military ATC procedures and training, relating to hijack and other emergency situations, are reviewed and harmonised.
Development of the strategic initiatives involved consultations among Member States and with the European Civil Aviation Conference (ECAC), the Commission of the European Communities, airspace users, the military, the International Federation of Airline Pilots Associations (IFALPA), and the International Federation of Air Traffic Controllers’ Associations (IFATCA).
The objective of this project work is to demonstrate the feasibility for enhancing ATM security by making available key security related information in encrypted form to decision-makers. This will necessitate a secure radio link between the ground and the aircraft. The and the technology being validated adoptedused is an adaptation of that adopted for the IMT-2000 CDMA air interface standard. (Suitably corrected for Doppler and range)
The background study has been completed.
Successful flight trials at C-band have been conducted to a range of 90 Nautical Miles. Theseis demonstrateshows that the adapted CDMA standard can be used for aeronautical security applications in the band 5091-5150 MHz. Further validation flight trails are planned infor the first half of 2006 using a European ground network and civil aircraft. to alpha test such a new system.
2 KEY FEATURES OF THE NEW AERONAUTICAL SECURITY SYSTEM
The proposed system is capable of supporting security. It acts primarily as an aeronautical security system, however it provides additional functionality.
Its primary functionality includes:
· to provide mutual authentication of ground and air networks;
· to provide the exchange of encryptedion informationkeys between aircraft and ground for secure communications;
· to provideFor downloading in real time ‘black box’ information to and from the aircraft including basic aircraft parameters, such as position, and video. This independent information from aircraft close to an airport could also be used for runway incursion determination calculations and would complement the Airport Wireless Surface Network (AWSN).
To optimize spectrum efficiency, any excess capacity experienced could be used for alternate functions, including:
· To datastream critical security information from the aircraft including cockpit and cabin video and pilot alarms
· toUnder failure of the primary AMRS system (at the moment VHF, but to be replaced by the future AMRS system), provide enhanced connections between pilot and controller should confidentiality of information be essential;
· to provide enhanced data flow between aircraft and ground systems;
· to support passenger related applications (e.g. provision of real time confidential medical data);
· to provide functionality for UAV operations. For example, in the landing phase it may be necessary to download, in real time and with minimal latency, information to recreate a virtual cockpit for the ground-based pilot. This could involve video streaming in the last instances of flight.
3 RADIO SPECTRUM COMPATIBILITY ISSUES FOR SECURITY APPLICATIONS
3.1 ADDITIONAL ASSOCIATED TELEMETRY FUNCTIONALITY
· To provide common interface with NATO and military functions
· To integrate with the Airport Network location Equipment (ANLE)
· To provide future functionality for the UAV AMS requirements.
· There may be a requirement to integrate with the aeronautical telemetry equipment used for pre flight testing. This system could be taken over and used for in flight monitoring
ADDITIONAL ASSOCIATED ARNS FUNCTIONALITY
· Backward compatibility with ANLE
SECURITY ASPECTS FOR THE RADIO LINK
Given that the air-ground link could use a derivative of an IMT-2000 standard, link level security could be provided by re-using the facilities of that standard. The important aspects for this link are:
· Strong mutual authentication of the mobile (aircraft) and ground network. This would provide the functionality of protecting the infrastructure from granting access to unauthorised users. It also prevents the aircraft from being seduced into attaching to unauthorised infrastructure (e.g. infrastructure which has been set up to carry out active attacks on the link encryption);
· The mutual authentication is used to provide keys to encrypt and integrity-protect radio signalling on the air-ground link, including resource allocation requests and commands. This protects against various denial of service (resource exhaustion) attacks, and also some hiding of information about resources granted;
· The same keys are also used to encrypt all user data on the link. The encryption is applied at the RLC[1] layer, which hides all upper layer information (such as IP[2] headers as well as the actual data itself). This makes interception on the radio link essentially impossible, except for basic traffic analysis. This would reveal some information about the traffic mix (including the flow asymmetry between uplink and downlink, and balance between real time and non-real time data).
Issues
Compatibility with the following operational and potential systems is essential:
· Microwave Landing System (MLS)
· AM(R)S
· ANLE (AWSN – Airport Wireless Surface Network)
· Existing FSS feeder links
· Aeronautical telemetry
3.2 MLS
MLS must be protected and aeronautical safety regulators would need to be satisfied that no harmful interference would result. Frequency management solutions are possible given that operation in the MLS extension band is envisaged and that a total bandwidth of 15 MHz (3 x 5 MHz) is planned. Furthermore, the 5 MHz channels do not need to be contiguous.
3.3. Compatibility with existing FSS feeder links
CURRENT DEVELOPMENTS
Studies and flight trials have been undertaken to validate the use of adapted[3] IMT-2000 standards (W-CDMA and IS-95). Systems conforming to these adapted standards have been investigated in the band 5091-5150 MHz using analysis, simulation and validation through flight trials. The work concluded that adapted IMT-2000 systems operating in this band could well satisfy the infrastructure requirement.
This compatibility analysis follows a similar methodology to the one applied to an equivalent ANLE analysis conducted by the MITRE Corporation and discussed in ITU WP8B meetings.
Methodology and Parameters
Ground Antenna
The elevation polar pattern used in the analysis is based upon a manufactured unit as is shown below:
Interference Estimation
The received interference by the LEO-D satellite is determined by:
Pr=Pt+(Gt-Lc)+Gr-Lfree(d)-Lfeed-Lp+Bf-Dc
where:
Pr = received power in dBm
Pt = transmitter power in dBm
Gt = ground antenna gain (dBi)
Lc = ground feeder loss
Gr = satellite gain (assumed to be 6 dBi)
Lfree = free-space path loss (dB)
Lfeed = feed loss (dB)
Lp = polarization discrimination (dB)
Bf = bandwidth factor (dB)
Dc = Duty cycle reduction
Lfree = 32.44 + 20log(freq)+20log(d)
where:
Freq = frequency in MHz
D = distance in kms
Simulation Assumptions
It was assumed that the transmitter power was 40 dBm and that a total of 200 ground stations would be required. For the purposes of simulation it was assumed that there would be 70 stations in each 5 MHz band.
Furthermore, it was assumed that these stations would be uniformly spread along a line beneath the satellite orbit. In practice many ground antennas would be directional in azimuth thereby reducing interference.
Simulation Parameters
The following parameters were used:-
Number of ground stations / 70Transmitter power / 40 dBm
Feeder loss including switch and connectors / 4 dB
Satellite antenna gain / 6 dBi
Frequency / 5100 MHz
Polarisation discrimination / 1 dB
Transmitter bandwidth / 5 MHz
Satellite receiver bandwidth / 1.23 MHz
Satellite range / 1414 kms
Interference threshold / -155,5 dBW
Simulation Result
The initial results are summarized overleaf where the x-axis represents the satellite orbit reflected onto the earth’s surface. 0 km represents the mid-point with the 70 ground stations evenly spread over 2000 kms (i.e. -1000 km to + 1000 km):
However, it is noted that the FSS feeder link would cause interference to the aeronautical security system during aircraft transit of the beam.
3.4 Telemetry
The airframe manufacturing industry has stated a preference for 60 MHz (5 x* 12 MHz channels) of radio spectrum and one administration has identified the band 5030-5150 MHz. Given that airspace for flight testing is well defined and is predominantly offshore or out of the main aviation routes and TMA areascan be offshore, it is envisaged that frequency co-ordination with MLS and other potential systems could avoid interference.
Radio LAN
It has been proposed that an aeronautical RLAN (ANLE[4]) be sited at airports to, among other things, combat runway incursions.
In its most basic form, ANLE is a high integrity, “safety rated” wireless local area network for the airport area, combined with a connected grid of multilateration sensors. The former would provide the cockpit with access to appropriate information via a high-bandwidth internet-like connection. The latter would use those same transmissions to derive 3-dimensional position of the terminal – position that could then be broadcast via the same data link to provide all users with situational awareness on the airport surface. Adding simple transmitters to other surface-movement vehicles would allow for the development of a high-fidelity complete picture of the airport surface environment.
RLAN technology allows avoidance of specified frequencies. It is therefore possible to consider its interoperability with MLS provided non-interference with MLS could be demonstrated to the satisfaction of aeronautical safety regulators.
Fixed Satellite Service
The FSS uses, among others, the band 5091-5150 MHz for Earth-Space links. The ground stations are relatively few and transmissions are restricted to within 100 km of each site. The FSS would not be subject to interference itself but could cause interference to an aircraft passing through the radio beam. Again frequency co-ordination could be applied to remove such interference.