Presentation on theme: "Michael Neale Brooks Cressman Hau Ho ICAO ACP WG-F/24 March 21, 2011."— Presentation transcript:
Michael Neale Brooks Cressman Hau Ho ICAO 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 2
Required Throughput (RTCA & ITU) Telecommand: 10 kbps Telemetry: 320 kbps UA Densities (RTCA) 1856 UA in regional beam (3M mi 2 ) 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 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 3
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. 4 Typical 20/30 GHz satellite 3 dB spot beamwidths 0.5º (~310 km beam diameter/nadir) 1.0º (630 km beam diameter/nadir).
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
6 Band Type of Allocation UA Terminal Antenna Study Summary Disadvantages/ Potential IssuesAdvantages 10 MHz of the & 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 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
7 BandStudy summaryDisadvantagesAdvantages 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 100s of satellites on orbit Global coverage Used for decades to provide BLOS service to UAS > 500 MHz in each direction 13/15 GHz bands Cant share with the existing and planned systems in these bands Unacceptable interference to passive sensors in adjacent bands Spectrum limitation 22/23 GHz bands Cant 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 ~ % 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. 8
Ku-band- Telemetry link - 20º E.L. Ku-band- Telecommand link - 20º E.L. Ku-band 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. 10
UAs are size, weight & po wer (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 11
13 Sensors Flight Computer Sensor 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 ( Δ T/T). Operators can also separately request a Coordination if they find a Δ T/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 14
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 15
16 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.