Iris Public Event, 4-5 February 2013, Unv. Of Salzburg Unipark Antares Communication Standard Design

Transcription

1 Iris Public Event, 4-5 February 2013, Unv. Of Salzburg Unipark Antares Communication Standard Design February, 5 th, 2013

2 CONTENTS 01 - CS consortium 02 - End-to-end network architecture 03 - CS Design Drivers 04 - CS Main Characteristics 05 - Flexible system configurations supported by the CS 06 - Features & benefits of the CS 07 - CS public documents 2

3 ANTARES CS consortium Spac e Engineering S.p.A. 3

4 End-to-end network architecture (I) From an E2E view, the communication path consists of: Aircraft network and host Satellite network (AGDL) Terrestrial network (with several GGR) ATC/AOC centre network and host The CS specifies the air interface of the Satellite Network It covers up to the network layer. 4

5 End-to-end network architecture (II) Support of two network layer stacks: ATN/IPS Provides a standard IPv6 interface. Supports ATN/IPS compliant network layer mechanism. ATN/OSI (legacy) Same OSI sub-network dependent network layer functions supported as in current VDL2 networks (Mobile SNDCF, v8208). Eases integration with existing avionics. Dialogue Service Interface (DSI) ULCS TP4 IS-SME CLNP IDRP ES- IS Join/Leave Events Mobile SNDCF (incl. LREF) v Packets ABR (CMU) UT 5

6 CS Design Drivers Support of both data and voice Air/Ground communications for ATS and AOC services Meeting Class-of-service (CoS) requirements from COCR for current and anticipated ATC and AOC services Implications from the Aeronautical environment Efficient use of limited L-band spectrum resources User terminal design (Omni-directional aircraft antennas) Support of any aircraft type flying under IFR Compatible with multiple satellite orbital constellations (GEO, MEO and HEO) Flexible CS design to be compatible with centralized and distributed GS architecture, allowing an incremental deployment. CS specification aimed for global standardization process 6

7 CS Main Characteristics (I) Forwad Link from GS to UTs Based on MF-TDMA technique Forward link synchronization mechanism to assure that all the forward link carriers are received synchronously by the user terminals Baud rate = 160 kbauds, BW = 200 khz, L band spectrum resources Robust and flexible coding (IRA LDPC) and modulation schemes (MPSK) Support of Adaptive Coding & Modulation (ACM) to adapt the coding and modulation to the channel propagation conditions. Intra-burst interleaver to spread the channel errors produced by the aeronautical mobile channel. Forward link resources allocation providing flexibility to adapt to different GS architectures with different number of GS elements. 7

8 CS Main Characteristics (II) Return Link from UTs to GS Random Access scheme based on Asynchronous Code Division Multiple Access (A-CDMA) Enhanced Spread Spectrum ALOHA (E-SSA) combination of Spread Spectrum ALOHA (SSA) with Successive Interference Cancellation (SIC). Burst formats adapted to the different application messages sizes and latency requirements Chip rate of 160 kchips/s, bandwidth 200 khz, spreading factors 4 & 16 (flexibility to support higher chip rates). Powerful FEC scheme based on Turbo code 1/3, block lengths from 288 to 2048 bits. Congestion Control: mechanism based on the measurement of the channel load conditions by the Ground Segment 8

9 CS Main Characteristics (III) MAC / LL Layer CoS oriented taking into account packet priority depending on stringent delay requirements ARQ mechanisms based on positive ACK Optimized state of the art encapsulation scheme (GSE-like) providing an efficient encapsulation of L2 Data Units over variable-length L1 Data units. Control functions Flexible control procedures to support different GS architectures. Log on procedure which establishes associations between UT and GS elements. Seamless handovers between GES, between mobile link beams and between different satellite. Handover relies on signal quality measurements (based on ACM) to detect a need for handover. Broadcast of system tables including Forward and Return carriers parameters and system information. 9

10 System configurations supported by the CS (I) CS Reference architecture 10

11 System configurations supported by the CS (II) Flexible CS to support different System configurations CS compatible with multiple satellite orbits (GEO, HEO and MEO) using the same user terminal. CS allow a flexible GS architecture GS as a black box for the UTS Hybrid control architecture: combination centralized and distributed Centralized access (one GES) / Decentralized access (multiple GES) Allowing an incremental deployment Star architecture: just one NCC/GES Multistar architecture, centralized control: One NCC /GES + N GES s Multistar architecture, hybrid centralized / distributed control: One NCC /GES, control functions that need to be centralized (Congestion control, FWD RRM) Several NCC / GES s, control functions that can be distributed (logon, handover, ACM) Additional GES can be supported 11

12 CS Features & Benefits (I) CS Forward Link Waveform Based on MPSK / LDPC coding (QPSK ¼ to 16APSK 2/3) Adaptive Coding & Modulation scheme to the channel propagation conditions maximizing the spectral efficiency Robust techniques as interleaving and adaptive equalization to counteract aeronautical mobile effects Symbol rate of 160 Ksps driven by the L-band spectrum allocation based on frequency chunk of 200 khz. All possible flight conditions, as banking. Low gain antennas in the UT (omnidireccional) to reduce its costs. Fixed-wing to rotary-wing aircrafts (Scenario 2: fix wing, C/M 15 db) 12

13 PER Antares Communication Standard Design Iris Public Event, 4-5 February 2013, Univ. of Salzburg Unipark CS Features & Benefits (II) CS Return Link Waveform Based on Spread Spectrum A-CDMA exhibiting high robustness to multipath effects. Robust FEC for supporting Interference Cancellation: 16-states binary PCCC, Code rate = 1/3 Chip rate of 160 Kcps, driven by the L-band spectrum allocation based on frequency chunks of 200 khz. Takes advantage of the received packet power unbalance enhancing the Interference Cancellation receiver performance Allows the use of low gain antennas and constrained amplifier power 10 0 RTN-ACDMA - Rs=10k, SF=16, DW= Sc = 1 Sc = 3 Sc = 4 Sc = 2 Sc = E b /N 0 (db) Fix wing (1 to 4) & Rotray wing (9) C/M 5 to 20 db Elevations: 5º to 35º 13

14 CS Features & Benefits (III) CS Forward MAC (1) MF-TDMA access for the forward link, resources (frequency & time) allocated by NCC to the GES s according to: Overall trafic load to UT and its distribution among GES. Any operator criteria Forward link synchronization mechanism to assure that forward link carriers are received synchronously by the user terminals Able to cope with multiple satellite orbits (GEO, HEO and MEO) Scheduling, priority management and queuing / buffering policies Compliant with application CoS requirements: Message transit delay and service continuity Current and future ATC & AOC services. 14

15 CS Features & Benefits (III) CS Forward MAC (2) 15

16 CS Features & Benefits (IV) CS Return MAC A-CDMA random access scheme to efficiently support delay sensitive short and long messages. Congestion Control To assure that the random access channel is not overloaded. CoS oriented taking into account packet priority depending on the service delay requirements. Parameters set adaptively by the Ground Segment according to measured channel load conditions and then broadcasted to all UTs System efficiency maximized by a full frequency reuse. 200 KHz Bw, 512 word, processing gain 48 16

17 CS Features & Benefits (V) CS Control layer ACM control function based on monitoring of the Packet Error rate in the UT receiver Fast mechanism to identify a fast link degradation (e.g. due to maneuverings. Slow mechanism to select the most efficient MODCOS to track the channel state. Handover control: Seamless handovers between GES, between mobile link beams and also between different satellites Support for non-geo scenarios Log on /off and system tables providing flexibility to different system implementations. CS Network layer Designed to be able to transport ATN/OSI or ATN/IPS flows, facilitating initial deployment. v 17

18 ANTARES CS documents List of Communications Standard public document Communication Standard Technical Specification Communication Standard Implementation Guidelines Document Communication Standard Design Definition File Publication dates First draft: April 2012 Second draft: January 2013 End of design : April 2013 Final version : April

19 Thank you! Joan Manuel Cebrian Equipos de Comunicaciones Indra 19