Open and Extended Systems

Transcription

1 Open and Extended Systems December 2017, AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 1

2 Contents Definitions Pros and Cons What the Open System has to do How to ensure that it all works How to improve on the simple solution 2017 Xtera Proprietary 2

3 Definitions, Benefits and AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 3

4 "Open" (from on-line dictionaries) Allowing access, passage, or a view through an empty space; not closed or blocked up; exposed to the air or to view; not covered 2017 Xtera Proprietary 4

5 Traditional system Terminal equipment monitors Line (LME) and Power Feed Equipment (PFE) There are around four types of PFE There are two flavours of Line Monitoring PFE Subsea repeaters Terminal LME 1. Passive: loops / reflective filters subtleties e.g. BU switching 2. Active: send a command, get a response 2017 Xtera Proprietary 5

6 Open system one definition Wet-plant (incl. PFE and LME) designed to accept any Terminal Terminal can ignore power-feeding and line monitoring DRY Transmission Multiplexing Switching Supplier 2 WET LANDING POINT PFE Subsea repeaters LME Supplier 1 Any terminal should work, providing it can tolerate the Line Dispersion, Noise etc. from the subsea cable 2017 Xtera Proprietary 6

7 Open systems the Pros and Cons PROS CONS Competition Optimisation can pick the best individual units Long-term flexibility not tied to a particular supplier More complex contractually More technically demanding More complicated Network Management 2017 Xtera Proprietary 7

8 Traditional system Back-to-back terminals at Landing Point Full regeneration minimises noise DRY WET LANDING POINT PFE Transmission Multiplexing Switching ILAs Transmission Multiplexing SLTE LME Requires lots of back-to-back connections Expensive More complex to increase capacity 2017 Xtera Proprietary 8

9 Extended system Transmission goes directly from source to delivery point DRY part includes Intermediate Line Amplifiers (ILAs) DRY LANDING POINT WET Transmission Multiplexing Switching ILAs PFE Subsea repeaters LME Significantly less equipment lower cost / faster capacity increase Extra noise from ILAs 2017 Xtera Proprietary 9

10 Extended system the transmission challenge The noise and distortion of wet and dry parts are effectively added Each amplifier section contributes noise and distortion DRY WET Subsea repeaters Transmission Multiplexing Switching ILAs Noise contribution of an amplifier = Constant x Noise Figure / Input Power Reduce noise by: Closer amplifier spacing cost increase Lower noise figure not always possible Higher output power will increase non-linear distortion 2017 Xtera Proprietary 10

11 Extended system a different supply split Intermediate Line Amplifiers (ILAs) could be part of "wet" supply DRY LANDING POINT WET Transmission Multiplexing Switching Supplier 2 ILAs PFE Subsea repeaters LME Supplier 1 For example to get lower noise amplifiers in the dry part 2017 Xtera Proprietary 11

12 Extended system split three ways Intermediate Line Amplifiers (ILAs) could come from a third supplier DRY LANDING POINT WET Transmission Multiplexing Switching Supplier 2 ILAs Supplier 3 PFE Subsea repeaters LME Supplier 1 For example if the terrestrial link already exists Has three 2017 Xtera Proprietary 12

13 Commercial / Contractual issues AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 13

14 Commercial / Contractual issues The DRY and WET parts must inter-work at the traffic level Need to have correctly designed interface specifications Need to consider acceptance criteria The must give unambiguous fault indications Important for warranty and technical support to work Need to consider fault conditions 2017 Xtera Proprietary 14

15 It's no different to a third-party upgrade? Almost true Build and upgrade Open Solution 1. Build a system with terminals 2. Test and commission 3. Operate 4. Test / Assess system Can use some operational data 5. Add third party terminals 1. Build a system without terminals 2. Test and commission Don't want to delay contract No operational data 5. Add third party terminals How to commission and accept without terminals? 2017 Xtera Proprietary 15

16 There are other solutions Use just one supplier initially Use two suppliers initially No third-party equipment, but extra ports for later connection Initial supplier SLTE used to validate wetplant performance Includes third-party equipment, contractual requirement to work Third party SLTE used to validate wetplant performance + Only a single supplier Hard to be sure that the system is really open + Can choose "best" suppliers? Easier to be sure that the system is really open? Use an independent test service 2017 Xtera Proprietary 16

17 Network Management AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 17

18 What to consider regarding DRY equipment much more complex than WET Performance data for many wavelengths Configuration changes are likely WET equipment simpler Periodic repeater scans; PFE voltage & current Configuration is likely to be static Will be two, or more, Could have an higher level system or shared hardware (next slide) OSS Transmission Multiplexing Switching PFE Subsea repeaters LME 2017 Xtera Proprietary 18

19 Virtualisation to share resources Need a mechanism to see alarms in other windows WET SW DRY SW DRY window Server Client machine DCN Transmission Multiplexing Switching PFE Subsea repeaters LME 2017 Xtera Proprietary 19

20 Security Or the lack of it? Virtualisation only compartmentalises the software elements Should consider if there is good system-level protection Do third-party SLTEs have subsea control capability? Especially important with switchable Branching Units Are there any specific issues to be addressed? 2017 Xtera Proprietary 20

21 Testing / Validation AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 21

22 What the Terminal Supplier needs to know Fibre: attenuation fibre core size dispersion determines non-linearity Repeater: output power may vary with wavelength bandwidth noise figure Other: repeater spacing loss of in-line equalisers may vary with wavelength Interface: line-amplifier noise figure may vary with wavelength optical levels may vary with wavelength connector types These should define the performance of the submerged portion How can they be validated? 2017 Xtera Proprietary 22

23 How to validate the WET part After the first phase of the build 1 Wet Supplier's Terminal Subsea repeaters Wet Supplier's Terminal Proves that the system works in for one supplier Is it representative? Dry supplier may use a different modulation or have different performance 2 Wet Supplier's Equipment Subsea repeaters Spectrum Analyser Provides OSNR and Q is clearly related to OSNR Useful, but may not expose non-linear issues 2017 Xtera Proprietary 23

24 Higher order modulation formats Bit Interleaved Coded Modulation 1 bit/symbol 100G 2 bit/symbol 200G 3 bit/symbol 300G 4 bit/symbol 400G BPSK QPSK 8 QAM 16 QAM -3 db 0 db 4 db 7 db more OSNR than QPSK Higher order formats need more OSNR typically higher signal levels risk of non-linear penalties 2017 Xtera Proprietary 24

25 Q and OSNR Example Q 2 (db) Back-to-back measurement (with noise loading) QPSK 8QAM XXX 16QAM OSNR (db/0.1 nm) 2017 Xtera Proprietary 25

26 Power budget (BOL Beginning Of Life) A BOL OSNR at full loading 1 Back-to-back Q at BOL OSNR 2 Propagation impairments 3 Other impairments 4 Margin for Q variations (5 sigma) 5 BOL Segment Q Segment OSNR 6 Repair and ageing impairments 7 EOL Segment Q 8 FEC limit at BER = 1E Non-optimal pre-emphasis 3.2 Wavelength tolerance 3.3 Polarisation effects 3.4 Supervisory impairment 3.5 Manufacturing etc. 3.6 Unspecified Can one use Segment OSNR in this way? 2017 Xtera Proprietary 26

27 Q and OSNR Example Q 2 (db) Back-to-back Real system Limit OSNR (db/0.1 nm) 2017 Xtera Proprietary 27

28 A possible solution G-OSNR Generalised OSNR (also known as Electrical OSNR) Uses a coherent detector to measure the OSNR at the decision point Measure statistical spread and constellation spacing covers ALL impairments includes non-linearity If the setup is representative, the resulting G-OSNR can be used Example measure G-OSNR using QPSK, then apply result to 16QAM 2017 Xtera Proprietary 28

29 Correct use of GOSNR Conditions need to be comparable Same WL grid Same power per wavelength Correct pre-emphasis Ideally: 1. Measure for a range of conditions 2. Check by doing some inter-operation testing 2017 Xtera Proprietary 29

30 Improving the Open Interface AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 30

31 Adding capacity later Should be considered initially Transmission Multiplexing Switching Supplier 2? PFE Subsea repeaters LME Supplier 1 Supplier Xtera Proprietary 31

32 Adding capacity later simple solution Use a multi-port coupler Transmission Multiplexing Switching Supplier 2 PFE Subsea repeaters LME Supplier 1 Supplier 3 Important to get wavelengths and levels correct 2017 Xtera Proprietary 32

33 Adding capacity later potential problems Example: Terminal fails Transmission Multiplexing Switching Supplier 2 PFE Subsea repeaters LME Supplier 1 Normal Loading Supplier 3 Fault Missing channels Will affect Supplier 3 wavelengths 2017 Xtera Proprietary 33

34 Make the wet interface handle the problem Wet Interface monitors input signals; adds loading when needed PFE Subsea repeaters Transmission Multiplexing Switching Supplier 2 Load LME Supplier 1 Normal Loading Supplier 3 Fault Loading 2017 Xtera Proprietary 34

35 Open + Control Control levels to avoid any interactions PFE Subsea repeaters Transmission Multiplexing Switching Supplier 2 Load LME Supplier 1 Normal Loading Supplier 3 Fault Loading Provides complete isolation of different terminals 2017 Xtera Proprietary 35

36 Summary Open systems offer several benefits, but may not be for everyone There are several flavours of Open Configuration Contractual arrangement Key technical challenge is Acceptance testing of the WET portion Other things to consider Network Management at least two solutions Security Isolation of different suppliers Whatever I forgot If you have questions or comments please them to Tony.Frisch@Xtera.com 2017 Xtera Proprietary 36

37 Thank you for listening Any questions? them to AGILITY INNOVATION PERFORMANCE 2017 Xtera Proprietary 37