Phoenix Communication System Architecture and Protocols Consolidated Design

Transcription

1 ESA Artes-10 Iris Phoenix Communication System Architecture and Protocols Consolidated Design Robert Schweikert (AUDENS ACT) Markus Werner (TriaGnoSys) ESTEC, Noordwijk

2 Presentation Outline Overview of objectives and scope of work AMSS basics Enhanced AMSS ( AMSS+ ) design System dimensioning Sensitivity studies Summary and Conclusions (AMSS = Aeronautical Mobile Satellite Service) Phoenix Final Presentation ESTEC, Noordwijk,

3 Objectives and Work Performed Based on existing Aeronautical Mobile Satellite Service (AMSS) as specified in ICAO SARPS: Development of extensions to meet future key user requirements Reuse as much AMSS protocol design as appropriate Focus on lower layers: Physical & link layer, incl. FEC coding Channel structure and rates Communication system architecture & dimensioning Protocol design impact Capacity analysis, channel & bandwidth dimensioning Link budgets & satellite parameters Sensitivity analyses Phoenix Final Presentation ESTEC, Noordwijk,

4 Aeronautical Mobile Satellite Service (AMSS) Key Characteristics ICAO approved air-ground data & voice communications including safety-critical services P- channel ( 10.5 kbps) Forward (FWD) direction, user traffic and signaling Time Division Multiplexing (TDM) T- channel ( 10.5 kbps) Return (RTN) direction, user data/messages Time Division Multiple Access (TDMA) R- channel ( 10.5 kbps) Return (RTN) direction, signaling/system managm. & user data Random Access (slotted ALOHA) channel (contention based) C- channel ( 21 kbps) Bi-directional circuit mode voice and data Phoenix Final Presentation ESTEC, Noordwijk,

5 Requirements, Assumptions, Constraints Phoenix key input and requirements COCR mainly short messages stringent delay requirements Voice comm.: a few seconds lasting message exchange Phoenix key challenges Increase bandwidth efficiency (e.g. reduction of guard spaces) Login, initial terminal acquisition without any navigation aid Meet specific AES terminal constraints Single TX channel Low gain antenna Tackle inherent multiple access efficiency issue <-> resource management Phoenix Final Presentation ESTEC, Noordwijk,

6 Key Design Elements for AMSS+ (1) Removal of the C-Channel concept; incorporation of voice data onto the P-channel in forward, and in the T-channel in return direction, respectively, Introduction of a modified P-channel with a channel bit rate of 42 kbps in forward direction, Introduction of 21 kbps modified T- and R- channel in return direction Proposed channel rates are a result of trade-off mainly between delay requirements and link budget limitations Phoenix Final Presentation ESTEC, Noordwijk,

7 Key Design Elements for AMSS+ (2): Queuing Analysis / Meeting Delay Requirements Strictly following the COCR queuing analysis, adapted to satellite case Tx delay (sec) Service Class Considering all applicable message/packet overheads Key requirement is the total delay (TT 95 ) including all delay elements Available delay for queuing (sec) P-channel rates (kbps) T-channel rates (kbps) Forward Return ,5 21 NETCONN DG-A 0,19 0,10 0,47 0,26 9,43 8,73 NETKEEP DG-A 0,12 0,06 0,34 0,19 9,47 8,80 ACL DG-C 0,12 0,06 0,34 0,19 1,07 0,40 ACM DG-C 0,16 0,08 0,34 0,19 1,05 0,40 AMC DG-D 0,12 0,06 0,00 0,00 3,47 2,99 ARMAND DG-D 0,31 0,16 0,34 0,19 4,27 3,70 C&P ACL DG-D 0,12 0,06 0,34 0,19 2,07 1,40 COTRAC (interactive) DG-D 2,32 1,17 4,03 2,13 0,96-0,54 COTRAC (Wilco) DG-D 1,91 0,96 4,03 2,13 1,17-0,54 D-ALERT DG-D 0,11 0,06 3,36 1,78 2,07-0,19 D-ATIS (arrival) DG-D 0,13 0,06 0,34 0,19 2,07 1,40 DLL DG-D 0,58 0,29 0,64 0,34 4,14 3,55 D-ORIS DG-D 0,56 0,28 0,34 0,19 1,85 1,40 D-OTIS DG-D 0,24 0,12 0,38 0,21 2,01 1,38 D-RVR DG-D 0,15 0,07 0,42 0,23 2,06 1,36 DSC DG-D 0,12 0,06 0,32 0,18 8,87 8,21 D-SIGMET DG-D 0,16 0,08 0,43 0,24 2,05 1,35 DYNAV DG-D 0,62 0,31 0,32 0,18 4,12 3,71 FLIPCY DG-D 0,13 0,07 0,53 0,28 2,06 1,31 FLIPINT DG-D 0,18 0,09 8,07 4,27 2,04-2,68 ITP ACL DG-D 0,12 0,06 0,34 0,19 2,07 1,40 M&S ACL DG-D 0,12 0,06 0,34 0,19 2,07 1,40 PPD DG-D 0,13 0,07 0,87 0,47 4,36 3,42 SAP (Contract Establishment) DG-D 0,12 0,06 0,36 0,20 2,07 1,39 SAP (Periodic Report) DG-D 0,00 0,00 0,38 0,21 2,13 1,38 URCO DG-D 0,13 0,06 0,32 0,18 2,07 1,41 Phoenix Final Presentation ESTEC, Noordwijk,

8 Key Design Elements for AMSS+ (3) In forward and return direction, the application of more efficient FEC, (such as turbo coding, rate 1/2 (data), rate 2/3 (voice) In forward direction, pre-compensation of the Doppler on the feeder uplink due to satellite motions as well as satellite oscillator drifts In return direction, establishment of closed loop (GES AES) frequency & timing control Phoenix Final Presentation ESTEC, Noordwijk,

9 Key Design Elements for AMSS+ (4): Random Access Because of permissible traffic load ~ 20%! of channel capacity on R/A -channel only signaling/system management data but no user data; For services requiring e.g. a periodic message transfer over a longer period of time (such as reporting type service) the allocation of a fixed resource share on the T-channel; Signaling on R/A channel (resource request, termination info) only at beginning and end of the service Phoenix Final Presentation ESTEC, Noordwijk,

10 Key Design Elements for AMSS+ (5): P- and T- Channel Parameters Phoenix Final Presentation ESTEC, Noordwijk,

11 Key Design Elements for AMSS+ (6): R/A-Channel Concept and Parameters Supports fixed assignment and random access Phoenix Final Presentation ESTEC, Noordwijk,

12 Handover and Mobility Handover of AES between (i) ground earth stations (GES) and (ii) beams/satellites is basically supported in AMSS Beam and GES handovers in current AMSS require log-off/log-on of AES with corresponding communication interruption To meet future ATM comms requirements, further work on AMSS+ should include seamless handover frequency/timing synchronisation between intra-ges and inter- GES carriers Integration with higher-layer mobility (e.g., mobile IP) is important for future work consider existing frameworks (ETSI-BSM/SI-SAP, IEEE ) consider ongoing project work (NEWSKY etc.) Phoenix Final Presentation ESTEC, Noordwijk,

13 System-Level Issues of Comms System Design Overall capacity and bandwidth requirements over space and time break-down into channels and services Potential of frequency reuse Link budgets (for spot beams) Phoenix Final Presentation ESTEC, Noordwijk,

14 Considered Services and Modelling Approach ATS (addressed) data - COCR message/queuing models AOC (addressed) data - COCR message/queuing models ATS voice - COCR voice parameters/erlang model AOC voice - ECTL voice parameters/erlang model (Broadcast and surveillance) - COCR message/queuing models Domain-specific message and call parameters according to COCR Completely parametric calculation/simulation throughout Propagation, MAC, and transmission delays considered before queuing analysis! Phoenix Final Presentation ESTEC, Noordwijk,

15 Spot Beam System and Frequency Plan Phoenix Final Presentation ESTEC, Noordwijk,

16 Reference Results: Normalized Worst Case Capacity and Channels Beam/Area Worst Case Capacities Required Number of Channels FWD RTN RTN Reservat. P T T R/A (voice+data) (voice+data) (surv.) Requests (v.+d.) (v.+d.) (surv.) [kbit/s] [kbit/s] [kbit/s] [req./s] S1 14,2% 11,4% 6,0% 0,8% 6,7% 10,5% 6,2% 1,6% S2 4,0% 3,0% 0,8% 0,1% 2,0% 3,0% 1,0% 0,2% S3 8,4% 5,1% 2,0% 0,4% 3,8% 4,8% 2,0% 0,8% S4 38,0% 28,9% 19,0% 2,7% 16,7% 26,8% 19,2% 4,8% S5 10,5% 7,1% 3,2% 0,5% 4,8% 6,5% 3,4% 1,0% S6 7,6% 4,6% 1,7% 0,3% 3,6% 4,4% 1,8% 0,6% ECAC non-adaptive 82,8% 60,1% 32,5% 4,8% 37,5% 56,0% 33,5% 8,9% ECAC adaptive 76,8% 56,5% 30,3% 4,3% 34,1% 52,2% 30,8% 7,7% R1 1,9% 1,4% 1,0% 0,2% 1,0% 1,4% 1,0% 0,4% R2 2,3% 1,1% 0,3% 0,1% 1,0% 1,2% 0,4% 0,4% R3 2,6% 1,2% 0,3% 0,2% 1,2% 1,2% 0,4% 0,4% R4 1,5% 0,9% 0,1% 0,1% 0,8% 1,0% 0,2% 0,2% R5 1,1% 0,9% 0,1% 0,0% 0,6% 1,0% 0,2% 0,2% R6 1,2% 0,9% 0,1% 0,0% 0,6% 1,0% 0,2% 0,2% R7 1,7% 0,9% 0,1% 0,1% 0,8% 1,0% 0,2% 0,2% SAT non-adaptive 95,1% 67,4% 34,6% 5,4% 43,5% 63,7% 36,1% 10,9% SAT adaptive 87,2% 63,1% 32,0% 4,8% 38,7% 58,7% 32,5% 8,7% Normalized RTN capacity 100% Normalized RTN channels 100% Phoenix Final Presentation ESTEC, Noordwijk,

17 Conclusions from Numerical Results Exclusion of surveillance services 30% less mobile uplink bandwidth Dominance of ECAC over rest of satellite/regional beams Dominance of ECAC center beam S4 > 50% of total traffic Hence, frequency reuse will be heavily limited by the inhomogeneous traffic demand saves some 30% in the overall bandwidth requirements, and thus achieves the upper limit of possible gain (for this number of beams) Adaptive configuration is supposed to gain some 10%, exploiting peak loads per beam appearing at different times of the day Phoenix Final Presentation ESTEC, Noordwijk,

18 Sensitivity Analysis (1): Scenario / Airspace Partitioning Worst-case scenario: satellite serves 100% of the traffic in all domains Beam/Area Worst Case Capacities Required Number of Channels FWD RTN RTN Reservat. P T T R/A (voice+data) (voice+data) (surv.) Requests (v.+d.) (v.+d.) (surv.) [kbit/s] [kbit/s] [kbit/s] [req./s] ECAC non-adaptive 82,8% 60,1% 32,5% 4,8% 37,5% 56,0% 33,5% 8,9% ECAC adaptive 76,8% 56,5% 30,3% 4,3% 34,1% 52,2% 30,8% 7,7% SAT non-adaptive 95,1% 67,4% 34,6% 5,4% 43,5% 63,7% 36,1% 10,9% SAT adaptive 87,2% 63,1% 32,0% 4,8% 38,7% 58,7% 32,5% 8,7% Reduced scenario: 87% 100% 87% 100% satellite does not serve APT, 5% of TMA, 5% of ENR voice, 50% of ENR data, and 100% of ORP traffic. Beam/Area Worst Case Capacities RTN RTN FWD (voice+data) (voice+data) (surv.) Requests FWD (v.+d.) (v.+d.) (surv.) Required Number of Channels FWD RTN RTN Reservat. P T T R/A [kbit/s] [kbit/s] [kbit/s] [req./s] ECAC non-adaptive 20,8% 4,3% 3,9% 1,7% 8,9% 4,8% 4,6% 3,6% ECAC adaptive 18,8% 4,0% 3,5% 1,5% 7,9% 4,0% 3,6% 2,6% SAT non-adaptive 30,8% 9,9% 5,2% 2,2% 13,9% 11,1% 6,5% 5,4% SAT adaptive 27,1% 9,2% 4,5% 1,8% 11,5% 9,1% 4,8% 3,4% 27% 15% 12% 17% Phoenix Final Presentation ESTEC, Noordwijk,

19 Sensitivity Analysis (2): Service Parameter Values There are some dominating /critical services Their inclusion and/or specific parameter values may influence the total capacity requirements significantly The design freedom to slightly exceed a particular message delay requirement may impact significantly as well Some sensitivity studies have shown tens of percent or even a few orders of magnitude differences There are other less impacting services For instance, the exact call duration of AOC/ATC voice is not that critical Phoenix Final Presentation ESTEC, Noordwijk,

20 Summary & Conclusions Work done Enhanced AMSS (AMSS+) protocol design Comm. system architecture and dimensioning Main findings A workable solution extending an existing protocol is possible Approach selected so far is considered a good starting point for potential further optimisation / efficiency increase Recommendations for future work Many of the lessons learnt applicable to both other starting points/ existing protocols new protocol design Impact factors to be monitored and/or fixed COCR message set and detailed requirements technology/user terminal development Phoenix Final Presentation ESTEC, Noordwijk,