Energy Limitations on Optical Data Transport and Switching. Rod Tucker University of Melbourne

Transcription

1 Energy Limitations on Optical Data Transport and Switching Rod Tucker University of Melbourne

2 Summary Top-down estimate of energy consumption of the Internet - Projections of current trends (AU) - Switches and routers - Optical transport ottom-up estimate - ased on theoretical and practical lower bounds - Transport energy - Switching energy - Network energy Putting the GreenTouch factor of 000 into context

3 Energy per bit (nj) Top-Down Analysis Data 0 Sub-wavelength Wavelength Core Router Ethernet Switch WDM Tx/Rx PIC Tx/Rx FEC Chip Optical Amp MEMS OXC OLT: DSL Modem: Set-top ox: HD IPTV: 50 nj/b 500 nj/b 000 nj/b 0,000 nj/b

4 Network Energy Model Core Network Tier Network Metro/Edge Network Access Network Core Router Fiber roadband Network Gateways Ethernet Switch DSLAM Cu DSL Edge Routers OLT Cabinet Splitter Fiber FTTP OLT Cabinet Cu FTTN ONU DSLAM Data Center Server Storage Server Storage Video Distribution Network

5 Transport Energy/it/000-km (J) Efficiency Trends Transport Systems 0-3 TAT- TAT % p.a. TAT-5 TAT-8 TAT-9 TAT-/3 TAT-0 TAT- 0-9 WDM terrestrial Year 040 0% p.a. efficiency improvement in routers (Neilson, JSTQE, 006) 3% p.a. efficiency improvement in routers (Tamm, LTJ, 00) 5% p.a. efficiency improvements in transport (Han, IEEE Comms. Mag. 00)

6 Energy per bit (mj) Average Access Rate (Mb/s) 00 Top-Down Analysis Total (using 00 Technology) Routers and switches Total (5% p.a. improvements) 0 0. Transport PON 40% p.a. Access Rate Growth Year

7 Total Network Power Consumption (W) Global Network Energy Consumption 0 Total (using 00 Technology) 0 Total (5% p.a. efficiency improvements) Routers and switches PON Transport 40% p.a. Access Rate Growth 0% p.a. Growth in user numbers Year.5 billion users Global electricity consumption (0) = x 0 W

8 Summary Top-down estimate of energy consumption of the Internet - Projections of current trends - Switches and routers - Optical transport ottom-up estimate - ased on theoretical and practical lower bounds - Transport energy - Switching energy - Network energy Putting the GreenTouch factor of 000 into context

9 Lower Limit on Optical Transport Energy Stage Stage m P Encode P TX P AMP P AMP P RX P Decode Encode TX a g a g RX Decode L stage Total Amplifier Energy per it E AMP P AMP r al stage SNR m e h bit AMP Amplifier Efficiency Total TX/RX Energy per it E TX / RX P P P P Encode TX RX Decode r Dominates it Rate R. S. Tucker, "Green optical communications - Part I: Energy limitations in transport," JSTQE, March/April 0.

10 Optical Transmitter P MUX P driver P driver P Laser Driver Driver Data In MUX Z mod Modulator Z mod Z mod Z mod Driver Driver P driver P driver C mod Z mod = or 50 Ω Lumped modulator Distributed modulator E C V E mod mod V 50 mod r ~ pj

11 Total Amplifier Energy, E AMP (pj/bit) Lower Limit on Transport Energy per it TX/RX OOK km total reach DPSK 0. AMP 00% Shannon bound for SE = b/s/hz Amplifier Spacing, L stage (km) 80

12 Spectral Efficiency, SE (b/s/hz) Shannon ound 0 Shannon ound 0-9 ER X X 0-9 ER Coding/decoding increased CMOS energy 0. - Advanced modulation increased TX/RX consumption increased SNR, E amp Signal to Noise Ratio per it, SNR bit (d) Efficiency Energy per it

13 Energy/it/000-km (J) Energy per it per 000-km 0-3 TAT- TAT TAT-5 TAT-8 TAT-9 TAT-/3 TAT-0 TAT- E total (Top down) 0-9 WDM terrestrial E min (ottom up) Year

14 Loss/Efficiencies and Energy Overheads Laser efficiency, system penalties, system margins, etc E function E E Total min function E overheads E E min Total Loss, Inefficiencies E min Key Function Subsystem Overheads Management and control, interconnects, power supplies, etc. Key Conclusion: Minimizing E min is not necessarily the best strategy for minimizing E Total

15 User Ports Access Network Access Network Network Energy Stage Transport Transport Stage s Switch Switch Switch Switch Switch Switch

16 Switching Energy user core user core user X 0 3 X X 0 3 X core user N user user ports core user X 0 3 X X 0 3 X core user core user X X core user aggregation q core stages disaggregation R. S. Tucker, "Green optical communications - Part II: Energy limitations in networks," JSTQE, March/April 0.

17 Switch Energies per it O/E Converters MUX/DEMUX

18 Network Energy per bit (J) Energy Improvements Current Trends Transport Routers and Switches 0-8 X 0 3 X X Switches Lower ounds X 0 x Transport X X Year

19 Packet Switching Electronic Packet Switch - No buffers Input wavelengths () :k DEMUX m O/E (30 pj/b) Forwarding Engine m (30 pj/b/stage) Forwarding Engine k m x m Electronic Switch (/k) k x k Electronic Switches (/k) k k: MUX E/O m (0 pj/b/stage) (45pJ/b) m Output wavelengths ()

20 Optical Packet Switch Driver m x m Optical Switch () E/O Input wavelengths () m m Output wavelengths () O/E :k DEMUX m m k: MUX Forwarding engine, header replacement (/k) Power off during payload?

21 Energy per it per Switch, E bit (J) Lower ound on Energy in Packet Switching Excludes Forwarding Engine Optical Packet Switch Semiconductor Optical Amplifier Electronic Packet switch Arrayed WG Micro-Ring Switch Capacity: m = 000 Tb/s it Rate per Wavelength or Waveband, (Gb/s)

22 Conclusions Top-down and bottom-up estimates of energy differ by ~ x0 4 Theoretical limits on optical transmission are well defined Not so for networks Optical packet switching offers no clear advantage over electronic packet switching