UAS BLOS (satellite) Control and Non-Payload (CNPC) Communications Michael Neale Brooks Cressman Hau Ho ICAO ACP WG-F/24 March 21, 2011

Agenda UAS SWAP Limitations 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

Data Rate and Spectrum Requirements 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 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

Spot Beam Satellite Technology 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. Typical 20/30 GHz satellite 3 dB “spot” beamwidths 0.5º (~310 km beam diameter/nadir) 1.0º (630 km beam diameter/nadir).

Potential BLOS Frequency Bands Studied in WP5B 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)

L-band AMS(R)S Overview (RTCA) Type 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 Two NGSO MSS in this band Spectrum limitation - only 4 MHz in each direction (HIBLEO 2) L-Band spectrum not sufficient for all projected UAS Requirements

Above 5 GHz Study Summary – Advantages & Disadvantages 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 20/30 GHz bands – commercial satcom Support UAS control links 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 & Ka band System Study Summary (Based on ITU-R WP 5B) 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.

Ku & Ka band System Availability Ku-band Ka-band Ku-band- Telemetry link - 20º E.L. Ka-band- Telemetry link - 20º E.L. Ku-band- Telecommand link - 20º E.L. Ka-band- Telecommand link - 20º E.L.

Ka Band Link Margin Summary 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.

UAS SWAP Considerations 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 SWAP

0.76m Ku Band installation

1.2m Ku Band Installation Sensor data processor Sensors Flight Computer Sensors

FSS Operating Environment 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

Conclusions (1/2) 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

Conclusion (2/2) 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.”