Current Status of LDACS Development Michael Schnell German - - PowerPoint PPT Presentation

Current Status of LDACS Development

Michael Schnell German Aerospace Center (DLR)

www.DLR.de • Chart 1

ICAO Communications Panel 1-5 December 2014 Presentation of IP01

Motivation The Future Communications Infrastructure (FCI)

www.DLR.de • Chart 2

Motivation Air/Ground Communications

www.DLR.de • Chart 3

From Voice to Data … DSB-AM: Analog Voice VDL2: Kind of SMS … to Internet and SWIM LDACS: Connectivity

Outline

www.DLR.de • Chart 4

Achievements and Current Status of LDACS LDACS1 Extension Towards Navigation Conclusions Open Issues

Achievements and Current Status of LDACS Brief Review of LDACS

• L-band Digital Aeronautical Communications System (LDACS) is the

future ground-based communications link within the FCI

• Two proposals: LDACS1 and LDACS2
• Deployment in L-band (960-1164 MHz)
• L-band already heavily used by
• Aeronautical navigation services
• Aeronautical military communications systems
• Different deployment options
• Use only lower part of L-band, 960-978 MHz (LDACS2)
• Use lower and upper part of L-band, 960-978 MHz / 1150-1157 MHz
• Slight rearrangement of L-band assignments for radar navigation
• Inlay scenario (preferred approach for LDACS1)

www.DLR.de • Chart 5

Achievements and Current Status of LDACS Brief Comparison Between LDACS1 and LDACS2

• LDACS1 can utilize more spectrum in L-band due to inlay approach; no

reorganization of spectrum assignments required

• LDACS1 is the broadband LDACS proposal (fivefold bandwidth) making

available considerably more capacity

• LDACS1 applies modern communications concepts (OFDM)
• LDACS1 considerably more mature than LDACS2
• Continuous development since 2007
• Detailed evaluations of PHY and MAC layer
• Receiver concept with strong robustness against interference
• Numerous publications (> 30 since 2007)
• Several demonstrators/prototypes available
• Europe: DLR, Frequentis AG, Rohde & Schwarz
• Japan: ENRI, GNU radio implementation
• China: BUAA, hardware implementation, flight testing

www.DLR.de • Chart 6

Achievements and Current Status of LDACS Potentials of LDACS1

www.DLR.de • Chart 7

• LDACS1 enables high-capacity aeronautical communications
• Min. net data rate (FL+RL=overall):

291+270 = 561 kbit/s

• Max. net data rate (FL+RL=overall):

1.32+1.27 = 2.59 Mbit/s

• Well suited to serve modern ATM application and future needs
• Comparison with LDACS2 (overall):

70-115 kbit/s

• LDACS1 is highly flexible and scalable, enables long-term evolution
• OFDM based physical layer
• Scalability towards higher data rates
• LDACS1 foresees quality-of-service
• Fast access to resources and low delays for application
• Different priorities for different applications
• LDACS1 enables integration of navigation functionality

Achievements and Current Status of LDACS LDACS1 Work in Europe

www.DLR.de • Chart 8

SESAR JU Project P15.2.4 ATM Research in Europe LDACS1 Demonstrator Developed by FRQ Compatibility Testing at DFS labs SESAR 2020? Mature Technology, Update Specification

Achievements and Current Status of LDACS LDACS1 Work in Germany

www.DLR.de • Chart 9

DLR Internal Projects Receiver Optimization Interference Mitigation Receiver Concept Demonstrator Complete Transmitter Software Receiver

Achievements and Current Status of LDACS LDACS1 Work in Germany

www.DLR.de • Chart 10

ICONAV German National Project with R&S as Industry Lead LDACS-COM Hardware Implementation Including Security LDACS-NAV DLR Internal Project MICONAV Follow-on Project

Achievements and Current Status of LDACS LDACS1 Work Outside Europe

www.DLR.de • Chart 11

Japan ENRI (Electronic Navigation Research Institute) LDACS1 Demonstrator Based on GNU Radio Hardware Implementation China Beihang University (aka BUAA) National Key Laboratory of CNS/ATM Theoretical Studies and Simulation on LDACS1 Demonstrator Implementation Preliminary Flight Tests in (May 2014)

LDACS1 Extension Towards Navigation Navigation Functionality for APNT

• What is APNT? Alternative Positioning Navigation and Timing
• Why APNT? For the GNSS failure case!

www.DLR.de • Chart 12

GNSS becomes primary navigation means Navigation services require high performance for all phases of flight Large distance SAT-aircraft, GPS easily jammed Newark Liberty Int’l Airport

“GPS Jammer” Personal Privacy Device

LDACS1 Extension Towards Navigation LDACS1 as Pseudolite System

www.DLR.de • Chart 13

Continuously transmitting LDACS1 ground stations act as pseudolites: “GPS on Ground” Aircraft performs pseudo-range measurements towards LDACS1 ground station

LDACS1 Extension Towards Navigation Performance Bounds on Ranging With LDACS1

www.DLR.de • Chart 14

5 10 15 20 25 10 10

1

10

2

10

3

10

4

Carrier to Noise Ratio [dB] Mean Range Error [m] Schmidl-Cox Synchronization

• Freq. Domain: Synchronization Symbols

Time Domain: Synchronization Symbols CRLB: Synchronization Symbols

~4.1 m ~4.1 m ~230 m Theory:

• Cramer Rao Lower Bound (CRLB)
• Mean range error several meters

Simulations:

• Slight adjustments to sync.
• Theoretical bound achievable

@ reasonable C/N Reality:

• Performance in real environment?
• Flight measurement campaign!

LDACS1 Extension Towards Navigation Flight Measurement Campaign

www.DLR.de • Chart 15

f/MHz 960 970 GSM 975 965 962 TACAN

LDACS A LDACS B LDACS C LDACS D

Three flight levels:

• FL100
• FL280
• FL380

LDACS – L-band Digital Aeronautical Communications System > Michael Schnell > October 2014

30 km

LDACS1 Extension Towards Navigation Range Estimation Results – Whole Flight

www.DLR.de • Chart 16

• 60
• 40
• 20

20 40 60 0.02 0.04 0.06 0.08

µ = 6.7 m RMSE = 15.2 m

Estimation Error [m] Probability

µ = 6.7 m RMSE = 15.2 m Raw range estimates, averaged over 1 s time intervals

LDACS1 Extension Towards Navigation Range Estimation Results – Whole Flight

www.DLR.de • Chart 17

• 60
• 40
• 20

20 40 60 0.02 0.04 0.06 0.08

µ = 6.7 m RMSE = 15.2 m

Estimation Error [m] Probability

µ = 6.7 m RMSE = 15.2 m Main error source: Multipath propagation Main error source: Troposphere Second campaign for channel sounding Ranging algorithms: Maximum Likelihood Doppler Smoothing Particle Filtering Channel modeling Tropospheric models available Significant reduction

• f bias possible

Conclusions

• LDACS1 is well-suited to serve modern ATM applications
• High-capacity data link
• Highly flexible and scalable
• LDACS1 has been considerably matured within the last years
• First compatibility investigations (LDACS1  DME) have been

performed

• LDACS1 offers an excellent opportunity for extension towards navigation
• APNT service on top of communications infrastructure
• Theoretical ranging performance in the order of meters
• Measurement campaign validates navigation performance for APNT

www.DLR.de • Chart 18

Open Issues

• Further L-band compatibility evaluations for LDACS1
• DME/TACAN, UAT, SSR Mode S
• Military communications systems (JTIDS)
• Development of deployment concept for LDACS1
• Development of a migration strategy from VDL2 to LDACS1
• Development of final LDACS1 specification including technology

amendments as required and initiation of standardization

• Development of fully functional LDACS1 prototype and flight testing

www.DLR.de • Chart 19

www.DLR.de • Chart 20

Thank You!

More about LDACS1 www.ldacs.com