SPECTRUM‐SECURE COMMUNICATIONS FOR AUTONOMOUS UAS/UAV PLATFORMS Andrew L. Drozd ANDRO Computational Solutions, LLC Advanced Applied Technology Division Rome, NY
26 October 2015 Secure UAS Communications Panel 1 Unclassified // Distribution A: Unlimited Distribution Topics • ANDRO Technology Summary • Background of key technical issues related to UAS/UAV spectrum, safety, security and airspace integration . Potential spectrum contention and management issues
Frequencies Used for Remote Control
A Typical UAV Link
UAS Integration to NAS . Spectrum, Security and RTCA‐228 Relevant Issues • Conclusion 2 ANDRO Technology / Application Spaces
C2 (Cross‐layer RF Cyber‐Spectrum RF Resource Exploitation Management & Communications / Cyber Security) (Wireless Anti‐ EMI Avoidance Dynamic Spectrum Hacking) (Coexistence) Access/Sharing
Spectrum Pre‐test M&S Detect & Avoid (Spectral Contention)
Cyber‐Spectrum Exploitation / Secure Wireless Comms / Cognitive Radio Networking / 3 Trusted Routing Technologies for Autonomous Systems (RF sensor‐edge processing) BACKGROUND
• ANDRO has access to AFRL’s Stockbridge Controllable Contested Environment Facility and Griffiss FAA UAS Test Site Rome, NY for communications up/down‐link experiments with large or small UAS/UAV platforms.
• Member of Northeast UAS Airspace Integration Research Alliance (NUAIR).
• Our overall focus is on assessing, pre‐certifying or assuring the following for C2/CDL, payload data link (VDL) and other future RF comms technologies:
– RF spectrum collision/contention
– Coexistence
– Cyber Security (confidentiality/integrity/availability)
– Safety. 4 • Cell phone Daily Users of RF Spectrum • Cordless phone • Garage door opener • Car key remote control • Standard time broadcast • Mobile radio • GPS navigation • Microwave oven • Bluetooth • Wifi • Zigbee • Broadcast television and audio • Vehicle‐speed radar, air traffic radar, weather radar • RFID devices such as active badges, passports, wireless gasoline token, no‐contact credit‐cards, and product tags • Satellite TV broadcast reception; also backend signal dissemination • Toll‐road payment vehicle transponders • Citizen's band radio and Family Radio Service • Radio control, including Radio‐controlled model aircraft and vehicles • Wireless microphones and musical instrument links 5 Amateur Radio/Unlicensed Spectrum Bands: Frequencies Generally Used by Amateur UAVs
6 Frequencies for Remote Control (RC) Activities
FCC has reserved frequency bands for RC activities http://www.modelaircraft.org/events/frequencies.aspx
72 MHz: aircraft only (channels 21 through 35) 75 MHz: surface vehicles OLDer 53 MHz: all vehicles, older equipment on 100 kHz spacing Vulnerable to amateur 50.8 to 51 MHz: for all vehicles at 20 kHz spacing radio repeater stations 27 MHz: general use, hobbyists. NEWer 2.4 ‐ 2.485 GHz: Spread Spectrum band for general control 900 MHz, 1.2 GHz, 2.4 GHz, 5.8 GHz: common for video transmission 433 MHz or 869 MHz ‐ directional high‐gain antennas for video at increased range
7 Frequencies for RC Activities (Continued)
• Older RC aircraft in the US utilized 72 MHz for comms:
. Tx broadcasts using AM or FM with PPM or PCM.
. A specific channel is used for each aircraft.
. Use of crystals to set the operating channel in the Rx and Tx.
. For an aircraft controlled on channel 35 (72.49 MHz), if someone turns their radio on the same channel, the aircraft's control may be compromised, so when flying at RC airfields, there is normally a board that flags used channels to avoid incidents.
• Latest Rx use synthesizer technology and are 'locked' to the Tx. For synthesized Rx crystal is not needed, full bandwidth can be used (i.e., 35 MHz).
• Newer Tx use spread spectrum technology in the 2.4 GHz frequency for communication allowing pilots to transmit in the same band in proximity to each other with little fear of conflicts, and receivers in this band are virtually immune to most sources of EMI. 8 UAS / Airport Significant Frequencies
UAV control, telemetry, and video frequencies: Comms link metrics: • 900 MHz, 1.2 GHz, 2.4 GHz, and 5.8 GHz • 900MHz and 2.4GHz are popular because they have more relaxed FCC a) Data rate is the amount of data transferred, regulations for transmit power and duty cycle measured in bits per second (Bps), also called throughput b) Packet loss is packets received compared to Other UAV frequencies: packets sent, expressed as % • ADS‐B for aircraft below 18,000 feet: 978 MHz and 1.090 GHz • GPS: L1 and L2 at 1.2276 and 1.57542 GHz
Airport System frequencies: • Airport air‐to‐ground voice radio, ATM voice radio: 120 –135 MHz (VHF radios) • Airport ground radio: 460 MHz • Griffiss Airport Radars • ASR‐8 (airport ATM radar) is 2.7 –2.9 GHz, 20 MHz wide • SRC LSTAR is L‐band, 1.5 GHz • Doppler weather are L‐band and S‐band: 1‐2 GHz and 2‐4 GHz • The 700 MHz Band – between 698 and 806 MHz ‐‐ is public safety groups: police, fire, emergency services
9 A Typical UAV Link (for RC &Other Data)
Uplink is used to control/change flight • Periodic (1‐sec) to adjust flight parameters • ~900 MHz datalink • Messages ~1 kB, 56 kb/sec • Often Spread Spectrum and/or encrypted UAV Telemetry is aircraft flight data • Usually ~900 MHz datalink • Location, velocity, heading, altitude, battery life Uplink: Control Commands Downlink: Telemetry Data Payload data is typically video (digital) Downlink: Payload Data • up to 8 Mbit/sec for high quality video link Ground Control System • Control Tx & telemetry Rx • Video receiver Spectrum Management • Commercial digital video recorder Security Control • RSSI indicator 10 Radio Technical Commission for Aeronautics RTCA SC‐228 Phases / Timeline • Minimum Performance Standards for UAS integration into non‐segregated airspace –establish Detect &Avoid (DAA) and C2 Data Link capability: . Provides the C2 function as the primary use of the spectrum. . ITU has identified multiple spectrum band as candidates (L‐Band Terrestrial, C‐Band Terrestrial, SATCOM in multiple bands). . Minimum Operational Performance Standards (MOPS) for C2 Data Link: Specify equipment reqt’s for civil UAS; reqt’s in Phase I MOPS: L‐ and C‐Band Terrestrial data links Class A are not part of this TOR; consider reqt’s between the UAS and ground subsystem. Phase II MOPS: SATCOM in multiple bands Consider extended UAS operation in Class D, G, and E airspace; Ground taxiing is not part of this TOR. SC 228 Development Timeline:
12/2013 01/2014 – 06/2015 07/2015 – 06/2016 SC‐228 Whitepaper C2 Data Link MOPS for V&V C2 Data Link MOPS V&V Reqt’s for C2 Data Link for Develop prelim MOPS for Conduct V&V Test Program UAS integration into NAS. L‐Band &C‐Band solutions. 11 RTCA SC‐228 Scope Standards development for civil UAS equipped to operate into Class A airspace under IFR (instrument flight rules) Operational Environment: • UAS transitioning to/from airspace Class A, traversing D/E/G • Extended UAS operations in airspace Class D/E/G The C2 Data Link: standards for Link using • L‐band Terrestrial (960‐1164 MHz) data links Airport environment, low altitude, wideband‐ downlinks 960‐977 MHz – assignments for UA at en route cruising altitudes Need ‐ RF Spectrum for: 980‐1020 MHz – additional assignments to low‐ • Pilot ATC Communications Link (voice, data) altitude UA • UAS control link (telecom [uplink], telemetry [downlink]) • C‐band Terrestrial (5030‐5091 MHz) data links • GPS –determine location Narrowband uplinks; 300kHz channels and • ADS‐B ‐ broadcast position location submultiples (25,50,150) Repetition rates for Modes of Operation AeroMAX (broadband for airports) can be utilized for • Automatic ‐ 10 Hz • Manual ‐ 20 Hz (ITU‐R 643 Report M.2171 Tables streaming data from taxiing UA. 23 and 24). 12 • SATCOM in multiple bands Key Technical Issues in UAS Integration to NAS
• FAA identified relevant challenge areas:
. Communications
. Airspace UAS operations
. Unmanned Aircraft
. Human system integration
13 Key Issues (Continued) • Airspace UAS Operations . Separation Concepts: Collision Avoidance (CA), Self‐Separation (SS), and Separation Assurance (SA) . Airspace Integration Safety: Risks and failure modes of SA/SS/CA integration, including Cockpit Display of Traffic Information . Sense and Avoid Sensors and Fusion: Use on/off‐board sensors; radars; fusion of EO/IR, radar, SWIR, and ADS‐B . Separation Algorithms: Maneuvering algorithms for avoiding other aircraft, weather, wake vortices, terrain, etc. . Availability of Surveillance Data: Impact of existing data on intent/trajectory prediction . Terminal Airspace/Surface Operations: Complex and restrictive environment and responsiveness to ATC. • The Unmanned Aircraft . State Awareness and Real Time Mission Management: Negotiate changes in UAS trajectories based on aircraft operational state . Airframe Certification: Emphasis on structural analysis and reduction in airframe testing . Precise Location and Navigation: Alternative to GPS . UAS Avionics and Control: Means to ensure safety and reliability. 14 The Spectrum and Airspace Integration • RF spectrum . Protected safety RF spectrum for control communications . Cyber secure RF infrastructure FAA‐UAS‐operator . Control data link for given spectrum bands. • SC‐228 relevant issues . Evidence of old technology for link signal/spectrum and their management (narrow band, assigned bands, non‐adaptable, no feedback) . Assumed “equal bandwidth for all” or “bands for thee modes” limits number of users of a frequency band and constraint flexibility of frequency access/usage . Low power spread frequency waveforms not considered at all (will enable control without contention for 100s of systems simultaneously in the same frequency) . Evidence of limited consideration for link routing through relays, and multi‐hop high speed networking. 15 How to Improve • Good intentions: SC 228 suggests to relegate signals from L band to C band when possible for surface, low‐altitude, downlink uses; allow C in both directions with software‐ defined channel widths, support multi‐hop links, networking, etc. • Can improve with: . Interference analysis . Range & Signal Strength prediction and test analysis . Real‐time spectrum situational awareness . Spectrum management and interference mitigation . Spectrum sharing technology to address signal collisions: ‐ in L: Terminal Radar Approach Control (TRACON) signals, radar, etc., ‐ in C: Unlicensed National Information Infrastructure (U‐NII) signals, radar, etc. . Technology preventing link loss ‐ Lost Link Preparedness . Spread spectrum and frequency hopping waveforms . Different choice for carrier frequency ‐ Laws of physics favors lower freq. (< 700 MHz), which better penetrate structures, propagate to longer ranges due to lower absorption . Vulnerability analysis (cyber security) 16 Frequency / Modulation Selection
Spread spectrum and frequency Different choice for carrier frequency hopping waveforms
http://diydrones.com/profiles/blogs/some‐tips‐on‐picking‐frequencies 17 Lost Link Preparedness • 3 UAV links: uplink control, downlink telemetry, downlink payload ‐ any of these 3 links can be interrupted by various forms of interference. • When links are lost… • UAVs are programmed to fly in a circular pattern and work to re‐establish or restore the link. In worst‐case scenarios, they are supposed to return automatically to their launch base. • UAV pilots have told investigators that they were so accustomed to lost links that they tended not to get nervous unless the disruptions lasted for more than a few minutes. • Losses: ~200 mid‐size and large‐size UAVs lost in 2012‐2015, 25% associated to link loss. • Loss of communication during operations may result from: • Failure of system due to lack of reliability • Loss of line‐of‐sight (LOS) due to geographic features blocking the signals • Weakening of received power due to increasing distance to the UAV or UAV mobility (banking, antenna alignment) • Unpredictable, transient fades due to interference or jamming (intentional or inadvertent). 18 Interference Analysis (Pre‐Flight)
420 – 450 MHz 902 – 928 MHz 1.24 –1.3 GHz 2.39 – 2.485 GHz 5.47 – 5.825 GHz 5.15 –5.35 GHz
• For any selected UAV controller, one will be in contention with the above potential RF interference signals. • These may or may not be a concern. • If a concern is determined, provide recommends to mitigate potential interference or vulnerabilities. 19 Propagation Characteristics: Range & Signal Strength
• Atest site can be either a poor transmitting environment or a positive transmitting environment. • A UAV’s cruise speed 20 m/sec (48 miles/hour) will carry it 1 mile away in 72 seconds if it were to fly straight line away from the ground station. • Receive modules lose >50% of their signal at about 1.5 miles from the ground station, and receive sporadic transmissions up to 3 Packet loss and reception miles away. over a flight path • Ground ambient different than altitude ambient. 20 Link Protection vs. Malicious Intent ‐ Cyber Vulnerability Assessment ‐ • Control uplink mainly requires protection against unauthorized use • Typical Protection Measures: . 128‐bit AES encryption . Forward Error Correction coding, or similar, to both detect errors and increase decryption complexity . Transmit frequency hopping or other Spread Spectrum signal, where the bandwidth is increased at least 10X, which produces a LPI. • Malicious Threats: . Information corruption: Transmit control link signal spoof (gibberish) to disrupt and cause denial‐of‐service or link loss . Masquerade: Take over as Ground Control Station and gain control or hi‐jack the UAV. 21 FCC Regulations (Top Level)
• FCC rules and regulations are codified in Title 47 of the Code of Federal Regulations (CFR). Part 15 of this code applies to RF devices operating at unlicensed frequencies. (often referred to as FCC Part 15)
• Frequency allocation approval: Adapt the "J‐12 Process“
. Joint Frequency Panel of the U.S. Military Communications‐Electronics Board (MCEB) reviews the characteristics for RF equipment.
• $16,000 per day FCC fee for unauthorized transmit in licensed bands.
• The NATO Standard Agreement (“STANAG”) 4586 defines many of the command and control protocols used in military UAVs.
22 Summary &Benefits of Cyber‐Spectrum Management
Concern Benefit Lost Link Preparedness • No surprises during test success • Flight safety • Improves UAV flight test planning Interference Analysis: Characterize Test Site • Ensures compatibility of UAS with as “positive transmitting environment” other existing aeronautical systems Range & Signal Strength prediction and test • Improves UAV flight test planning analysis • Helps characterize the UAV range Vulnerability Analysis • Improves marketability of UAS/UAV • Credibility in FAA and FCC domains FCC / FAA Post‐Test Report • Complexities of integrating UAS/UAV into congested airspace
23 Contact Information:
Andrew L. Drozd,President & Chief Scientist [email protected]
Carmen Luvera, Director of Business Development [email protected]
ANDRO Computational Solutions, LLC The Beeches Professional Campus One Beeches Place 7980 Turin Road, Bldg. 1 Rome, NY 13440‐1934 (315) 334‐1163 www.androcs.com 24