Presentation on theme: "UAS Control and Non Payload Communications (CNPC) Link Availability"— Presentation transcript:
1UAS Control and Non Payload Communications (CNPC) Link Availability ICAO ACP-WG-F Meeting #24Paris, March Michael Neale and Brooks Cressman
2OverviewWhat levels of UAS Control and Non-Payload Communications (CNPC) Link Availability will be required?Safety driven analysis of Collision Avoidance Scenario.Dependent on Aircraft type, Class of Airspace, Operation.ICAO AMS(R)S Manual.What levels of Availability can be achieved?LOS and BLOS (satellite).Using frequencies likely to be approved at ITU WRC-12.An overall system view.A candidate UAS CNPC design solution
3Safety Analysis Analysis of a Collision Avoidance Scenario Conflict Avoidance Period 5-10 seconds.Collision Avoidance Period 5-10 seconds.CNPC Link temporary outage must last for less than 1-2 seconds during this second period.
4Safety AnalysisTarget UAS Midair Collision Rates per flight hour to be the same as manned aircraftAOPA NALL Report shows about 10 Part 91 (GA) manned aircraft midair collisions per year during approximately 25 million flight hours = 4x10^-7 per flight hour.NTSB and FAA data shows for manned Part 121 (airline and large cargo) aircraft no midair collisions during over 400 million flight hours = 2.5x10^-9 per flight hour.Collision LikelihoodCurrent estimates of the likelihood of an intruder, on a collision course with a UA, entering the UA's self conflict avoidance volume (self separation volume) is once every 10,000hrs. Collision Likelihood = 1x10^-4 per flight hour.Sense and Avoid and CNPC systems must reduce this Collision Likelihood to the target Midair Collision rates achieved by manned aircraft
5Safety Analysis Assuming no autonomous UA operation Collision Likelihood x SA & CNPC Unavailability < Manned Aircraft Midair Collision RatePart 91 Type UA Unavailability Case4x10^-7/1x10^-4 = 4x10-3Assume SA and CNPC systems share equal Unavailabilities.CC link Unavailability 1/2 x 4x10^3 = 2x10-3 = 0.2%99.8% CNPC Link Availability = Total outage of 2.88min per day.Part 121 Type UA Unavailability Case2.5x10^-9/1x10^-4 = 2.5x10-5CNPC Link Unavailability 1/2 x 2.5x10-5 = 1.25x10-5 = %% CNPC Link Availability = Total outage of 1.08 seconds per day.
6Safety Analysis Part 91 Type UA Unavailability Case Required CNPC Link Availability approximately 99.8%Part 121 Type UA Unavailability CaseRequired CNPC Link Availability approximately %ICAO Manual on Required Communications Performance Doc AN/462, 2008 prescribes a similar level of availability based on supporting ATC separation service.
7LOS CNPC Link Availability LOS Availability impairments compared to free spaceMultipath and Diffraction – low altitude e.g. takeoff and landing as well as earth curvature obstruction near maximum range.Airframe antenna obstruction - maneuvering during takeoff and landing as well as when flying straight and level en-route.LOS MultipathUsing ITU-R P.530 Propagation data and prediction methods required for the design of terrestrial line of sight systems – SectionAdditional propagation loss of 11-19dB (depending on frequency and aircraft altitude) added for 99.8% availability.
8LOS CNPC Link Availability LOS Installed antenna performance analysisUsing a single antenna yields dB nulls.Using two diversity controlled antennas gives 12dB nulls.Additional loss (12dB) added to link budgets to account for airframe obstruction
9LOS CNPC Link Availability AssumingControl - Telecommand and telemetry data rates 10kbpsPilot Voice Communication data rates 5kbpsSA/TCAS support data rates 10kbpsWeather radar and nose camera video 270kbpsL Band (circa 1GHz) and C Band (circa 5GHz) ITU preferred AM(R)S LOS frequencies.10 Watt transmitters2dB Noise Figure receiversRealistic system lossesTwo Omnidirectional antennas on the aircraftHigh gain antenna(s) at Control StationInclude 6dB safety marginApproximately 150km (80nm) rangeSingle Link Availability of 99.8% can be achieved
10BLOS CNPC Link Availability BLOS Satellite Availability impairments compared to free spaceL and C Band scintillation loss (<0.5dB).Ku and Ka Band.Rain and scintillation fading.Use ITU-R P Propagation data and prediction methods required for the design of Earth-space telecommunication systems - SectionAdditional propagation loss of dB depending on rain rate and altitude for 99.8% availability.Other Ku and Ka Band limitationsAircraft size and power capability, limits antenna size and transmit amplifier power output which limits EIRP and G/T and link margin.
11BLOS CNPC Link Availability Rain at lower altitudes causes additional propagation loss on Ku/Ka satellite linksUA can only use Ku/Ka Band satellites at aircraft altitudes where rain loss is not excessive. This limits the lowest altitude the UA can fly. UA will switch to LOS for takeoff and landing.Manned Aircraft avoid weather radar level 3 (red) and above regions where rain is higher than an R 0.01 of approximately 20mm/hr.
12BLOS CNPC Link Availability AssumingControl - Telecommand and telemetry data rates 10kbpsPilot Voice Communication data rates 5kbpsSA/TCAS support data rates 10kbpsWeather radar and nose camera video 270kbpsL Band (circa 1.6GHz), C Band (circa 5GHz), Ku (12/14GHz) and Ka Band (20/30GHz) frequencies10 Watt transmittersRealistic system lossesOmnidirectional antennas on the aircraft at L and C Band0.8m and 0.5m dish antennas on aircraft at Ku and Ka BandEIRP limited by uplink power flux density regulationsSingle Link Availability 99.8% can be achieved
13Candidate DesignA single CNPC link is probably adequate for Part 91 Type UA operating in class E or G airspaceA very effective way to achieve the availability needed for a Part 121 Type UA operating in class A, B or C airspace is to use two non- correlated CNPC systemsx = or % AvailabilityAlso mitigates against hardware and software failures.Use the multiple frequency bands that are being considered by ITU to provide the diversity.Dual links for larger UA already assumed in ITU-R M spectrum analysis.Allows some margin for other parts of the CNPC link.
14Candidate Design Part 91 Type UA Part 121 Type UA Operation in Class E or G airspace.LOS - Use Single L (1GHz) or C (5GHz) Band LOS link.BLOS - Use Single L (1.6GHz) or C (5GHz) BLOS link – only required for operation outside Visual LOS.If desiring to operate in class A, B or C airspace may be treated as a Part 121 Type UA if suitably equipped.Part 121 Type UAOperation in Class A, B, C or D airspace.LOS - Use Dual L (1GHz) and C (5GHz) Band LOS Links.BLOS – Use Dual L(1.6GHz) or C (5GHz) Band link and Ku (12/14GHz) or Ka (20/30GHz) Band Link.If desiring to operate in Class E, or G airspace may do so.
15ConclusionsA flexible dual band approach can deliver the levels of safety anticipated while affording a number of advantages:RedundancyUsing two non-correlated frequencies offers protection against equipment failure as well as improvements in availability.ScalabilityA smaller UA only requires a simple single AM(R)S L (1GHz) or C (5GHz) Band system for Visual LOS or Radio LOS operation.A larger UA, that can support more equipment, can achieve higher levels of availability.Interference ProtectionCombining an L(1.6GHz) or C (5GHz) Band AMS(R)S BLOS system with a Ku or Ka Band FSS system provides the interference protection of AMS(R)S with the ubiquity and payload data rate capability of FSS.
16Future LiaisonRTCA SC203 Control and Communications Work Group has developed a number of papers on:UAS CNPC SpectrumUAS CNPC SecurityUAS CNPC messaging and data requirementsUAS Candidate CNPC ArchitecturesUAS CNPC Required Communications PerformanceLatency, Availability Continuity, Integrity etc.Contact Michael Neale for copies of SC203 papers or to participate in RTCA UAS MASPS and MOPS developmentMichael Neale –Brooks Cressman –