LDACS1 Overview and Current Status

LDACS1 Overview and Current Status Datenlink-Technologien für bemannte und unbemannte Missionen DGLR Symposium München, 21.03.2013 FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 1

Outline Motivation Requirements and Preconditions Concepts and Capabilities System Overview Challenges Current Status and Next Steps FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 2

Motivation Key principles for the future ATM system: The 4D Trajectory The System Wide Information Management Automation Efficient communication services are required to enable these key principles! A future Air/Ground data link, supporting ATS and ATC services for all airspace users is such an enabler. Future ATM concept introduces new ATM services that are demanding in data exchanges (latency, capacity, availability, ) 4D Trajectories Management, ASAS, CDM, Meteo info, SWIM FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 3

European ATM Master Plan FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 4

Future Communication Infrastructure (FCI) Planned FCI Airport data link: AeroMACS ATM over satellite: ESA Iris, Antaris Terrestrial A/G communications: LDACS Two LDACS candidates: LDACS1 - Broadband system based on OFDM; combining B-AMC and P34 LDACS2 - Narrowband system based on single-carrier technology (GMSK); combining LDL and AMACS Alternatives to LDACS: VDL Mode 2: Capacity: 31.5 kbps gross data rate (~25 kbps L2 net data rate) MAC scheme: CSMA; inefficient, limited throughput; Planned channel assignment: 4 VHF channels Satellite Communications: ESA/Iris, Iridium, Inmarsat; Satellite beams cover large geographic areas; multi-beam antennas; Large delays due to multiple-access and distance FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 5

LDACS1 - System Environment Application Part of Future Radio System (FRS) Future Communication Infrastructure (FCI) Presentation ATN Application Session AR Transport TCP/UDP A/A-R Aircraft LAN AIR-ES Network IPv6 Adaptation SL LDACS1 A/G Link Data link LDACS1 LLC LDACS1 MAC A/G-R 1 Physical LDACS1 PHY GS G-Sub Networks LDACS1-Sub Network Ground Segment A/G-R n G/G-R AOC-ES ATS G-Sub Network AOC G-Sub Network ATS-ES FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 6

LDACS1 Concept OFDM-based cellular radio system using FDD with 0.5 MHz channel grid LDACS1 GS provides cell coverage with seamless handover between LDACS1 cells Centralized communication via ground station AS must log-on at the GS GS controls its ASs GS manages all resource requests Multiple-access schemes Forward link (FL): Broadcast OFDM Reverse link (RL): OFDMA-TDMA AS#1 LDACS1 Cell AS#2 L-DACS1 GS AS#n FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 7

LDACS1 Capabilities LDACS1 supports data and voice (optional) A/G communications Supporting ATS/AOC A/G data links for safety-critical services LDACS1 is designed to meet the COCRv2 requirements for future radio systems LDACS1 is designed for the aeronautical environment aeronautical channels (en-route, take-off/landing, parking) Capacity: FL net data rates from 291 kbps to 1.3 Mbit/s RL net data rates from 220 kbps to 1.04 Mbit/s Cell size: designed for 200 nm range (guard time of 1.2ms); Performs better with ~ 120 nm cells FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 8

LDACS1 Key Features: Cellular radio system with up to 512 users per cell. Acknowledged and unacknowledged point-to-point communication between ground-station and aircraft station. Unacknowledged multicast communication between ground-station and aircraft stations (ground-to-air direction only). Hierarchical sub-network architecture with transparent handovers between radio cells User- and cell-specific adaptive coding and modulation modes Local quality of service management using separate queues for different service classes. Guaranteed maximum duty cycle on the reverse link (Reverse Link Allocation Algorithm) FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 9

LDACS1 System Overview Framing Structure Superframe (240 ms) RA Multiframe 1 (58,32 ms) Multiframe 2 (58,32 ms) Multiframe 3 (58,32 ms) Multiframe 4 (58,32 ms) 6,72 ms RA 1 RA 2 DC Data RL Random Access channel (net entry) Broadcast Channel (cell information) Dedicated Control Channel (ressource request, ACK) Common Control Channel (mapping of FL and RL user data, ACK) BC Data CC Data FL BC Multiframe 1 (58,32 ms) Multiframe 2 (58,32 ms) Multiframe 3 (58,32 ms) Multiframe 4 (58,32 ms) FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 10

Challenges: Co-site Operation JTIDS Strong FEC coding for LDACS1 signal Limited airborne LDACS1 duty-cycle FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 11

Challenges: Deployment in L-band L-band is heavy occupied by the DME system It is difficult to find empty DME allocations to be used for LDACS1 DME is the preferred back-up system for GNSS navigation The number of deployed DME GSs may even increase in the near future Communications demands will probably continue to increase It would be desirable including the navigation capability within the LDACS1 communication system LDACS1 GSs could provide signals-in-space that could be used by an aircraft for ranging (requires further improvement of OFDM synchronization) Together with DME signals, it could be used for navigation This would reduce the need for additional DMEs and create place for further expansion of the LDACS1 communication coverage FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 12

Aeronautical L-band: LDACS1 Deployment GSM/ UMTS DME-X DME-Y DME-Y JTIDS/ MIDS FIXED RSBN Type 1/2/3 GPS/Galileo L-DACS1 A 960 960 1025 969 1008 1053 1065 1113 978 (UAT) 1030 (SSR/ ACAS) 1087 1090 (SSR/ ADS-B) 1150 1000.5 1164 985 1009 1048 1072 FL RL 1206 1213 1166 1563 Initial proposal Heavy pulsed interference (~ µs) High transmitting powers (~ kw) B RL FL MNWG proposal 4 LDACS1 sub-ranges: 1030-63 = 967 ± 3 MHz 1090 + 63 = 1153 ± 3 MHz C FL RL RL FL DFS proposal 963.5 970.5 MHz 985.5 1008.5 MHz 1048.5 1071.5 MHz 964 970 1150 1156 1149.5 1156.5 MHz FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 13

Challenges: Inlay Deployment Concept allows for placing LDACS1 channels on existing DME allocations or between current DME allocations -60 Careful frequency planning required! normalized power spectral density [dbm/hz] -70-80 -90-100 -110-120 -130-140 -150-160 -1-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1 frequency [MHz] FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 14

Challenges: Implementation Transmitter - PAPR reduction required (e.g. PAPR of 11dB reduction by 6dB -> peak TX power of +53 dbm; - Very stringent TX spectral mask -> linear transmitter - Phase noise requirements -> LO frequency accuracy of ± 0.1 ppm - Broadband noise power density of -145 dbc/hz ( f 4.0 MHz ) - AS TX Noise Density in Inactive State below -153 dbm/hz Receiver: - Dynamic Range: signal power range from -104 dbm to -21 dbm plus a PAPR of 11dB -> peak RX power of -10 dbm; - Immunity to strong pulsed interference; DME pulses with +25 dbm peak power should not damage any part of the receiver - DME pulses are de-sensitising the receiver; LNA recovery time less than 2us - Frequency Switchover Time of less than 0,5ms - Interference Detection and Mitigation (Pulse Blanking + Compensation) FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 15

LDACS1 Achievements - First LDACS1 system specification was completed 2008 and based on B-AMC, P34 and WiMAX - Current LDACS1 specification (03.2011) is a stable and mature baseline for further LDACS1 activities. Based on: - Detailed simulations of PHY and data link layer - Feedback from simulated data traffic patterns and performance evaluations (latency, continuity) derived from air traffic models. - Results from reference implementations and first compatibility tests - Reference implementation of the specification in System C - LDACS1 lab demonstrator from DLR - First L-band compatibility measurements (DLR/DFS) - LDACS1 Transmitter implementation for FL and RL (PHY and parts of DL Layer) with a transmission power: 42 dbm FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 16

Conclusion and Next Steps LDACS1 is well-suited to serve modern ATM application and future needs. No significant degradation in operation/performance of the present L-band systems due to the operation of the LDACS1 system Design of extension for long-term evolution - LDACS1 is highly flexible and scalable L-band compatibility testing of LDACS1 within SJU P15.2.4 Include the navigation capability into the LDACS1 communications system FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 17

Questions? FREQUENTIS 2013 # DGLR Symposium # LDACS1 Overview and Current Status # Bernhard Haindl # 13-03-21 # Page: 18