michael neale brooks cressman hau ho icao acp wg-f/24 march 21, 2011
TRANSCRIPT
Michael NealeBrooks Cressman
Hau HoICAO ACP WG-F/24
March 21, 2011
UAS Throughput and BLOS Spectrum Requirements (RTCA)• Spot Beam Satellite Technology and impact on spectrum
BLOS Candidate Frequency Bands (ITU WP 5B Study)• Study Summary – Advantages and Disadvantages
Ku/Ka FSS (Fixed-Satellite Service) Systems Performance• System Link Availabilities / Rain Fade calculations• Study Summary
UAS SWAP Limitations• Example installations
Operational Interference Environment Conclusions
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Required Throughput (RTCA & ITU)• Telecommand: 10 kbps• Telemetry: 320 kbps
UA Densities (RTCA)• 1856 UA in regional beam (3M
mi2)• 501 UA per spot beam (486 mi
diameter footprint) Spectrum requirements
(M.2171)• 169 MHz
1 satellite using global/regional beam
Small UA not supported
• 56 MHz (169/3) ≥ 3 satellites using regional beams UA uses directional antenna
• 46 MHz* ≥ 3 satellites using spot beams UA uses directional antenna
Sat#1 Sat#2 Sat#3
Coverage area
• The satellites can operate co-frequency if the UA uses a directional (high gain) antenna with sufficient off-axis performance
• The satellites cannot operate co-frequency if the UA has an Omni directional (low-gain) antenna due to interference
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Used on existing & planned 20/30 GHz band satellites
Relies on tens/hundreds of beams to achieve high Power Flux Density (pfd) and spectrum efficiency levels• Spot beams allow spectrum to be re-used across service area• Typical scheme is 4x frequency re-use to achieve their
required space isolation (see below). For UAS this means a minimum of 4x46 MHz is needed, but in reality each beam will have 125 or more MHz of spectrum to serve many applications.
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Typical 20/30 GHz satellite 3 dB “spot” beamwidths •0.5º (~310 km beam diameter/nadir) •1.0º (630 km beam diameter/nadir).
5030-5091 MHz • AMS(R)S allocation• 20 MHz spectrum in each direction• Currently no satellite on orbit
12/14 GHz also known as “Ku-band” satellites• FSS allocation• >200 geostationary orbit satellites (GSO) currently on orbit• 500 MHz (1 polarization) – 1000 MHz (dual pol.) in each
direction 20/30 GHz also known as “Ka-band” satellites
• FSS allocations• >10 Commercial FSS GSO satellites are currently on orbit• Several proposed systems will be on orbit in the next few years• 1000 MHz – 2000 MHz spectrum in each direction
13/15 GHz & 23/24 GHz• AMS(R)S allocations• Unable to share with other services (ITU WP5B studies) 5
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BandType of
Allocation
UA Terminal Antenna
Study Summary
Disadvantages/Potential Issues Advantages
10 MHz of the 1525-1559 & 1625-60.5 MHz MSS Allocation
GSO satellites
AMS(R)S Allocation
Low-Gain antenna (Omni)
Can support UAS control links
Link availability needs further study
Spectrum limitation One satellite per
region Shared with MSS
systems
Operate in AMS(R)S allocation
Satellites on orbit Global coverage
1610-1626.5 MHz
NGSO - MSS satellites
AMS(R)S Allocation
Two NGSO MSS in this band
Low-Gain antenna (Omni)
Can support UAS control links
Link availability needs further study
Spectrum limitation - only 4 MHz in each direction (HIBLEO 2)
One satellite per region
Shared with MSS systems
Operate in AMS(R)S allocation
Satellites on orbit Global coverage
L-Band spectrum not sufficient for all projected UAS Requirements
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Band Study summary Disadvantages Advantages 5 GHz bands May be able to support UAS
control links (BLOS)
• Sharing difficulties (MLS) • No satellite on orbit• Only ~5 MHz per spot beam
and1 satellite per region greatly constrains spectrum
• Operate in ARNS allocation • UA operates with omni antenna
12/14 GHz bands -- commercial satcom
• Support UAS control Links• Meet the UAS system link
availability
Operate in FSS allocation, not AMSRS
• 100’s of satellites on orbit • Global coverage • Used for decades to provide BLOS
service to UAS • > 500 MHz in each direction
13/15 GHz bands
• Can’t share with the existing and planned systems in these bands
• Unacceptable interference to passive sensors in adjacent bands
Spectrum limitation
22/23 GHz bands
• Can’t share with the existing and planned systems in these bands
• Unacceptable interference to passive sensors in adjacent bands
Spectrum limitation
20/30 GHz bands – commercial satcom
• Support UAS control links• Meet the UAS system link
availability
Allocated to the FSS and, in some bands, the MSS. No specific AMS(R)S allocation.
• Several satellites on orbit • Many more planned• > 1000 MHz in each direction • Service UAV using small antenna
Ku and Ka-band satellite systems can support UAS control links and meet the system link availability
Ka-band appears more suitable than Ku-band because it allows UA to operate with smaller antennas
Ka-band is more impacted by rain than Ku, but still achieves higher link availability
• Ka-band operates at higher pfd and Uplink EIRP density
To meet the safety levels, the UA control link availability is ~ 99.999%
UA will be equipped with more than one control link. If UA has two control link subsystems, each link only required to achieve 99.8%• CS (control station): 99.95%• UA: 99.85%
ITU-R WP 3M, 4A, 4B are currently reviewing WP5Bs analysis.
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UA - Fade Margin
UA Altitude
Freq: 14.25 GHzLink Availability: 99.85%
3.8 dB Fade Margin(-14 dBW/4 kHz, 0.8 m antenna
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UA - Fade Margin
UA Altitude
Freq: 11.95 GHzLink Availability: 99.85%
1 dB Fade Margin(10 dBW/4 kHz, 0.8 m antenna
Ku-band- Telemetry link - 20º E.L.
Ku-band- Telecommand link - 20º E.L.
Ku-band
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.1 km
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1 km
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UA - Fade Margin
UA Altitude
Freq:30 GHzLink Availability: 99.85%
14.6 dB Fade Margin(320 kbps,0.5 m ant. & 10 W)
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UA - Fade Margin
UA Altitude
Freq:20 GHzLink Availability: 99.85%
6.7 dB Fade Margin(-118 dB(W/m²/MHz, 0.5 m antenna
Ka-band
Ka-band- Telemetry link - 20º E.L.
Ka-band- Telecommand link - 20º E.L. 9
• Telecommand downlink (satellite-to-UA): If the UA operates with a 0.5 m antenna the system can achieve 6.7 dB rain fade margin.
• Telemetry uplink (UA-to-satellite): If the UA operates with a 0.5 m antenna and a 10 W transmitter the system can achieve a 14.6 dB rain fade margin.
• These rain fade margins would be adequate to achieve the desired link availability for most locations around the globe particularly when the UA is operating at altitudes higher than 1.5 km.
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UA’s are size, weight & power (SWAP) limited• Satcom equipment (antenna) impacts airframe design / size• Large antenna, or multiple equipment requires larger airframe,
increasing cost, complexity and limiting applications Antenna solutions tied to system architecture and UA
design• At lower frequencies, omni antenna on UAS is used with large G/T
on satellite – Drawback is spectrum cannot be re-used and only 1 satellite can be used per
region so more spectrum is required or UAS density is limited. Benefit is that antenna implementation is simple.
• At higher frequencies, rain fade is pronounced and high gain antennas are used to reduce SWAP, offset losses and meet off-axis requirements
– Examples : for a constant gain of 38 dB, • X band = 1.18 meter• Ku band = .86 m• Ka band = .47 m
– Upper limit on frequency due to increasing rain fade, and availability of satellite infrastructure.
– Ka band is a practical limit for rain fade (up to 14 db) CNPC satcom must also carry payload sensor data for
practical SWAP11
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Sensors
Flight ComputerSensor data processor
FSS Coordination process• FSS operators use ITU API/Coordination/Notification/BIU Filing process• Examination by ITU triggers Coordinations based upon proximity
(arc) or potential noise floor impact (ΔT/T). Operators can also separately request a Coordination if they find a ΔT/T exceedance
• Operators coordinate operating parameters to meet performance requirements
• ITU examines notices with respect to compliance with the Radio Regulations (RR)
• ITU definitively records assignments with favorable findings with respect to compliance with RR, including completions of coordination
• Assignment may be recorded if coordination is incomplete after 4 months of interference free operation
ICAO SARPS for UAS could require users to provide for backup spectrum for use in the event their channel was to receive interference
Aviation regulator will certify UAS operators based upon successfully meeting ICAO SARPS and national regulations
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ITU and RTCA studies indicate UAS requires 46 to 169 MHz of spectrum
• SWAP requirements and practical satellite design drive UAS toward low gain omni or smaller directional antennas in Ka band
• Resulting actual spectrum needs become 169, 184 MHz or more (500 MHz…)
Existing AMS(R)S allocations do not meet projected UAS needs
Additional spectrum is needed and FSS can be explored as a way to provide ready bandwidth, meet safety requirements, and support future UAS applications
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Call for additional studies in ICAO 1.3 background text
Currently: "Spectrum for UAS for safety and regularity of flight, and in particular when the UAS operates in civil airspace, needs to be accommodated under an allocation to the aeronautical mobile (R) service, aeronautical mobile satellite (R) service, or the aeronautical radionavigation service in order to receive the sufficient status and protection from harmful interference.“
Add: “STUDIES ARE REQUIRED AND UNDERWAY TO DETERMINE IF OPERATION OF UA UNDER OTHER RADIO SERVICES CAN BE ACCOMMODATED WHILE SATISFYING THE NECESSARY ICAO TECHNICAL REQUIREMENTS.”