The Outlook of Broadband
Optical Access Networks




                    Cedric F. Lam
                       林 峯
        ...
Acknowledgement & Disclaimer


•   Acknowledgement
    – Jessica Xin Jiang (Salira Networks)
•   Disclaimer
    – The mate...
Telecommunication Networks
  Backbone        Metro                     ATM
(Core) Network   Network                   Chan...
Broadband Access Network Drivers

•   Continuing growth of                             1000
    Internet and new
         ...
VoD – Killer Application

                          the Post-Office Model


                                          4 ~ ...
Rapid Storage and Processing Improvements




                             Source: E. Ayanoglu, UCI
VoD Enablers

Disk Based Video Servers
                                           DRAM Based servers




                 ...
VoD Penetration in the USA




Total number of households in the US: 116Millions



                                     S...
Global FTTX Development

•   Fiber to the Premises (FTTP)
    – RBOCs’ new weapon to compete with MSOs
    – FCC incentive...
US FTTH Deployment
                                                 Source: RVA Render
                      FTTH Homes Pa...
TDM vs. WDM

                                                              ONU1

                                         ...
Power Splitting TDM PON Infrastructure
                    Analog video overlay 1.55μm optional

                         ...
EPON vs. GPON
EPON Multi-Point Control (MPCP) Protocol
                                                     Report Frame
     Data frame...
GPON (GTC) Downstream Encapsulation
                                    125μs
                        Gigabit Transport Co...
GPON (GTC) Upstream Encapsulation

PLOu     PLOAMu     DBRu                      Payload


                               ...
EPON vs GPON – Physical Layer
                                             EPON                        GPON

Downstream da...
Per-User Bandwidth

•   Fully loaded 32-way split

                                   EPON      GPON
           Raw       ...
Typical Applications’ Bandwidth Requirements
Application       Bandwidth                      QoS
Video (SDTV)      3.5 Mb...
Changes in Network Traffic
         Daily traffic volume at a Google data center by hours



          When Google bought
...
Statistical Multiplexing Gain
                                                                   Perception time
30 Mb/s
 ...
VoD Bandwidth Characteristics
•    Video streams characteristics
      – High bandwidth usage
      – Highly asymmetric
  ...
How Much Bandwidth is Needed?
•   US Population Statistics (US Census Bureau
    http://www.census.gov)
    – Total Popula...
10GbE-PON


•   IEEE 802.3av, started March 2006

                          Downstream    Upstream
           Symmetric   ...
Symmetric and Asymmetric 10Gb-EPON Operation
                                                             10/1G Asymmetric...
10Gb-EPON Optical Spectrum Management - 1
                 Upstream TDM Overlay                1G ONU

      OLT          ...
Dilemmas of 10GbE-PON

     Split Ratio           1:16           1:32            1:64
Effective BW (Mbps)        545      ...
10GbE-PON Transmission Challenges

•   Dispersion Effect (increases as square of bit-rate)
    – EML (narrow modulated lin...
Technologies for 10Gb-EPON Transmission

  •   APD                                              3dB
       – Improves sens...
Technologies for 10Gb-EPON
•   SOA
    – 15dB gain
    – Operate at all λ
    – Planner technology (mass
      manufacture...
SOA / EDFA in 10Gb EPON
                                                                 10Gb/s ONU
      1 Gb/s Tx

     ...
Fiber Non-linear Effect (SRS)

                                                            1490nm (pump) penalty




10G

...
Fiber Non-linear Effect (SBS)
           Limits transmitted power




S. Ten, “SBS degradation of 10Gb/s digital signal in...
WDM-PON
    S. Wagner et al, JOLT, 7, 1759 (1989)




                                    W
             CO               ...
Waveguide Grating Router
                INPUT       OUTPUT
                  1     W    1
                  2     G    2
...
WDM on WDM


             W                       W




                                         ...
             D       ...
Athermal AWG Devices
Athermal AWG
Injection Locking of Upstream Laser




                             Spectrum before locking




                       Co...
Reflective SOA




Courtesy of ETRI and Korea Telecom
Planar Lightwave Circuit - ECL




             Courtesy of ETRI and Korea Telecom
WE-PON (WDM-E-PON)
~ 1000 users per feeder fiber (32λ x 32 TDM)




   WDM-PON used for metro backhauling
WDM is an effici...
Conclusion

•   Demands for bandwidth continue to drive broadband
    optical access network development
    – Digital and...
Thank you!
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The Outlook of Broad Band Optical Access Networks

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The Outlook of Broad Band Optical Access Networks

  1. 1. The Outlook of Broadband Optical Access Networks Cedric F. Lam 林 峯 Chief System Architect, OpVista Inc. 870 N. McCarthy Blvd, Milpitas, CA 95035, USA +1 (408) 719-6127, cflam@ieee.org
  2. 2. Acknowledgement & Disclaimer • Acknowledgement – Jessica Xin Jiang (Salira Networks) • Disclaimer – The materials presented here represents my own personal view which could be biased.
  3. 3. Telecommunication Networks Backbone Metro ATM (Core) Network Network Channel Bank DSL T1 Data DSLAM POTS ISDN Data IDSL G. S IAD HD SL Ethernet SONET Headend WDM Cable Mesh FC Modem etc. HFC Coaxial CMTS Fiber Node ONU 1 OLT ONU 16 PON PBX T1 100/10 BT GbE 100/10 BT Ethernet Router MTU
  4. 4. Broadband Access Network Drivers • Continuing growth of 1000 Internet and new Voice applications 800 Data – Quadruple play: • VOIP, IPTV, Broadband Data, 600 Total Traffic (Gb/s) Wi-Fi /Wi-Max (backhauling) – Storage Area Networks 400 – Peer-to-peer networking • Picture, movie & music sharing 200 – Network gaming 0 • Deregulation of the telecom service market 1990 1995 2000 2005 2010 Year – Telcos and MSOs get into each Coffman and Odlyzko, other’s market AT&T Labs, 1997
  5. 5. VoD – Killer Application the Post-Office Model 4 ~ 8 GBytes per DVD 24 to 48 hours 160 ~ 740kbits per second FY 2006, Revenue : $997mil, Net Income : $49mil. Source: www.netflix.com
  6. 6. Rapid Storage and Processing Improvements Source: E. Ayanoglu, UCI
  7. 7. VoD Enablers Disk Based Video Servers DRAM Based servers ⇒ Courtesy: Motorola (Broadbus) • High capacity storage • Advanced video processing and compression technologies – SDTV: ~ 3.5 Mpbs (MPEG-2) – HDTV: ~ 8-15 Mbps (MPEG-4) • Low-cost and high-bandwidth made available by WDM and Gigabit Ethernet
  8. 8. VoD Penetration in the USA Total number of households in the US: 116Millions Source: Forrester Research, 2005
  9. 9. Global FTTX Development • Fiber to the Premises (FTTP) – RBOCs’ new weapon to compete with MSOs – FCC incentive, no need to unbundle the link – Joint RFP issued in January 2003 • Verizon, SBC (now AT&T) and Bell South • Promote interoperability, create economy of scale – AT&T: Uverse; Verizon: FIOS • NTT – GE-PON based FTTH • Korea – WE-PON (WDM-Ethernet-PON) trial • Europe – Many carriers have selected G-PON for FTTx
  10. 10. US FTTH Deployment Source: RVA Render FTTH Homes Passesd FTTH Homes Connected (North America) ( North America) 10,000,000 9552000 2,500,000 9,000,000 8003000 2142000 8,000,000 2,000,000 7,000,000 6099000 1478597 6,000,000 1,500,000 5,000,000 4100000 1011000 4,000,000 1,000,000 3,000,000 671000 2696846 2,000,000 1619500 500,000 0 0 0 0 0 00 00 00 1,000,000 00 70 0 0 0 0 30 970000 0 0 0 35 5 0 00 47 0 46 5 322700 1 94 35 721 110 180 189000 55 10 22 38 6 7 8 1 213000 0 0 1 2 2 3 3 4 4 5 5 6 6 7 7 pt 002 pt 03 pt 04 pt 005 pt 06 pt 07 ar 01 ar 02 ar 03 ar 04 ar 05 ar 06 7 00 00 00 00 00 00 00 00 00 00 00 00 00 00 , 2 r, 2 t , 2 r, 2 t , 2 r, 2 t , 2 r, 2 t , 2 r, 2 t , 2 r, 2 t , 2 S e , 20 S e , 20 S e , 20 S e , 20 M 20 M 20 M 20 M 20 M 20 M 20 Se , 2 Se , 2 ,2 pt a p a p a p a p a p a p , , , , , , pt Se M Se M Se M Se M Se M Se M Se Se • Up to Sept 2007 • Growth rate: – 2.14mil homes connected – 112% annually – 9.5mil households passed – 300,000 households passed every month
  11. 11. TDM vs. WDM ONU1 2 ... 16 • APON RT 1 2 . . . 16 1 ONU2 • BPON (a) OLT 1 2 . . . 16 • GPON • ... Power splitter EPON 1 2 ... 16 ONU16 RT ONU1 • Future λ1 Upgrade ONU2 (b) OLT λ2 λ16 ... WDM Coupler ONU16
  12. 12. Power Splitting TDM PON Infrastructure Analog video overlay 1.55μm optional Downstream 1.49μm ONU 1 PBX Upstream1.3μm >1:16 T1 central office 10/100BASE-T Backbone OLT 1 OLT OLT 2 Network switch OLT 3 PS OLT 4 ONU 16 10 ~ 20km • Power splitter remote node • Single fiber connection • Upstream and downstream signals separated by wavelengths (1.3μm/1.49μm) • Optional 1.55μm broadcast analog signal overlay
  13. 13. EPON vs. GPON
  14. 14. EPON Multi-Point Control (MPCP) Protocol Report Frame Data frames are not shown here! rpt 1 MPCPDU ONU 1 DA 6 octets overhead Ethernet gte1 gte 2 gte 3 gte n rpt 2 ONU 2 SA 6 octets OLT rpt 3 Type (0x88-08) 2 octets PS ONU 3 Op-code 2 octets rpt n 64 Octets ONU N Timestamp 4 octets • Bandwidth request and grant are achieved through MAC Control Paramerters MPCP protocol ... – ONU request upstream BW through REPORT frames – OLT send BW allocation to ONU using GATE frames Zero Padding • Pros FCS 4 octets – Only standard 802.3 Ethernet MAC frames are used New MAC control messages – Maximum compatibility with Ethernet GATE op-code = 02 • Cons REPORT op-code = 03 REGISTER_REQUEST op-code = 04 – Each MPCPDU is a 64-byte Ethernet MAC frame with its REGISTER op-code = 05 own overhead REGISTER_ACK op-code = 06 – OLT sent GATE frames individually addressed to each ONU for BW allocation ⇒ Large protocol overhead, less efficient use of BW Ref: IEEE 802.3ah
  15. 15. GPON (GTC) Downstream Encapsulation 125μs Gigabit Transport Container (GTC) Frame header (PCBd) DS Downstream Payload US BW map Alloc-ID Start End Alloc-ID Start End Alloc-ID Start End 1 100 300 2 400 500 3 520 600 US T-CONT1 T-CONT2 T-CONT(3) (ONU1) (ONU2) ONU(3) Slot Slot Slot Slot Slot Slot 100 300 400 500 520 600 • Less overhead – Media Access Control (MAC) information for ALL ONUs piggybacked into the same frame. • ITU-T G.984.3 Source: ITU-T G.984.3
  16. 16. GPON (GTC) Upstream Encapsulation PLOu PLOAMu DBRu Payload GEM Frame GEM Frame GEM GEM Full frame Frame fragment header fragment header header • Dynamic bandwidth report piggybacked to upstream encapsulation. No separate frames used. • G-PON Encapsulation Mode (GEM) – Support Ethernet frame fragmentation – Support encapsulation of other formats – More efficient packing of data – Native support of TDM traffic Source: ITU-T G.984.3
  17. 17. EPON vs GPON – Physical Layer EPON GPON Downstream data rate (Mbps) 1000 1244 or 2488 155, 622, 1244, or Upstream data rate (Mbps) 1000 2488 Payload Encapsulation Native Ethernet GEM TDM Support Circuit Emulation Native Laser on/off 512ns ≈13ns Upstream burst AGC ≤400ns mode receiver 44ns CDR ≤400ns • GPON – Power control required in GPON to achieve short AGC time – High speed laser drivers required for fast on/off time in GPON, difficult to realize • EPON – Relaxed component requirements (20~30% cheaper equipment) – Can even use traditional AC-coupled receiver as EPON burst mode receiver
  18. 18. Per-User Bandwidth • Fully loaded 32-way split EPON GPON Raw Downstream 31.25 78 Bandwidth (Mbps) Upstream 31.25 39 / 78 Bandwidth Efficiency 72% 92% Effective Downstream 22.5 71.8 Bandwidth (Mbps) Upstream 22.5 35.9 / 71.8 • US RBOCS don’t think EPON meets their future bandwidth requirements – To compete with GPON, IEEE started 802.3av 10GbE-PON task force in March 2006
  19. 19. Typical Applications’ Bandwidth Requirements Application Bandwidth QoS Video (SDTV) 3.5 Mbps Low loss, low jitter, constant bit rate Video (HDTV) 8-15 Mbps Same as above Telecommuting 10 Mbps Best effort, bursty Video gaming 10 Mbps Low loss, low jitter, bursty Voice 64 kbps Low loss, low latency, constant bit rate Peer-to-Peer 100 kbps – 100 Best effort downloading Mbps • 100Mbps – Download an 8GB DVD movie in 10 minutes – Blue Ray: 25 to 200GB per disk
  20. 20. Changes in Network Traffic Daily traffic volume at a Google data center by hours When Google bought YouTube! D. Lee, OFC 2008, paper OThB1 • Traditional web surfing is user active, network passive • Video is user passive, network active.
  21. 21. Statistical Multiplexing Gain Perception time 30 Mb/s “equivalent circuit rate” 10 Mb/s B “avg rate” “avg rate” detail 500 ’10Mb/s’ surfers sharing a 30Mb/s channel (40 kb/s average) t • Web-surfing – Poisson packet arrival distribution • Equivalent circuit rate – The perceived circuit rate experienced by users – 500 users with average usage of 40kb/s – Each user perceives as if he/she has 30Mb/s – (500x40kb/s) = 10Mb/s N.K. Shankaranarvanan, ATT, “User-perceived peformance …” Proc. ICC, June 2001 N.J. Frigo, “Fiber to the home: niche market …” OFC 2004 Tutorial
  22. 22. VoD Bandwidth Characteristics • Video streams characteristics – High bandwidth usage – Highly asymmetric – Uniform and steady packet arrival rate • Video consumptions are highly peaked during prime viewing hours or special events such as soccer games. • Statistical multiplexing gain no longer valid Video Peak viewing usage rate hours Hour 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 of day
  23. 23. How Much Bandwidth is Needed? • US Population Statistics (US Census Bureau http://www.census.gov) – Total Population: 300mil, Number of households:116mil – Average 2.6 people per household • 24 ~ 45Mb/s bandwidth per household – Enough for everyone at home to watch a different HDTV at the same time (without counting background download jobs, which can take advantage of statistical multiplexing). – Good before another killer application emerges • GPON will be able to support fully loaded VoD BW requirements and have room to grow … • EPON have barely enough BW when VoD takes off. – Shrink the service group, 1:8 ONUs per OLT – Develop 10GbE PON
  24. 24. 10GbE-PON • IEEE 802.3av, started March 2006 Downstream Upstream Symmetric 10Gb/s 10Gb/s Asymmetric 10Gb/s 1Gb/s • Backward compatible with 1G E-PON – WDM overlay – Dual rate OLT receiver
  25. 25. Symmetric and Asymmetric 10Gb-EPON Operation 10/1G Asymmetric 10/1G Asymmetric ONU OLT 10G Rx 10G Tx 10G DS (1.577/1.590μm) 1G Tx 1G Rx 1G US 1.310μm 1:16 10G Symmetric 10G Symmetric ONU OLT 10G Rx 10G Tx 10G DS (1.577/1.590μm) 10G Tx 10G Rx 10G US 1.270μm 1:16 To be finalized by IEEE802.3av task force.
  26. 26. 10Gb-EPON Optical Spectrum Management - 1 Upstream TDM Overlay 1G ONU OLT 1G Rx 1G DS (1.490μm) WDM 1G Tx 1G Tx 10G DS (1.577/1.590μm) 10G Tx WDM 10G ONU (Asymmetric) 1G US 1.310μm 1G/10G Rx 10G Rx 1:16 WDM 1G Tx Dual rate OLT receiver May incur 3dB splitting loss 10G ONU (Symmetric) at OLT 10G Rx WDM 10G Tx To be finalized by IEEE802.3av task force.
  27. 27. Dilemmas of 10GbE-PON Split Ratio 1:16 1:32 1:64 Effective BW (Mbps) 545 272.5 137 • Higher splitting ratio desirable to achieve better cost sharing and more efficient use of available BW – 1:64 or 1:128 (recall that each HH requires only ~45Mb/s BW) – May need to extend coverage distance for bigger share group size (e.g. up to 60km) • Further worsens the physical challenges for 10Gb/s PON signal transmission
  28. 28. 10GbE-PON Transmission Challenges • Dispersion Effect (increases as square of bit-rate) – EML (narrow modulated line width) – EDC may be needed at ONU receiver • Power Budget Extension – 9.1dB more theoretical received power requirement compared to EPON (8B10B GbE vs. 6466B 10GbE coding) Split Ratio 1:32 1:64 1:128 Loss (dB) 15 18 21 Fiber length 20km 40km 60km Loss (dB) 4 8 12 – 15 to 27dB more power budget required from OLT to ONU – Penalties (dispersion, fiber non-linearity) • Fiber non-linearity – Limit power budgets
  29. 29. Technologies for 10Gb-EPON Transmission • APD 3dB – Improves sensitivity by 7~8dB • EDC – 2~3dB gain • FEC 7dB – Improves power budget by 3~5dB F. Chang, “10G EPON Optical Budget Considerations” http://grouper.ieee.org/groups/802/3/10GEPON_study /public/july06/chang_1_0706.pdf 4.4dB
  30. 30. Technologies for 10Gb-EPON • SOA – 15dB gain – Operate at all λ – Planner technology (mass manufacture) – Compact size, (multi- channel packaging available) – Beneficial for burst data Burst data SOA EDFA L. Spiekman, IEEE802.3av meeting, Nov, 2006, Dallas, Tx http://grouper.ieee.org/groups/802/3/av/public/2006_11/3av_0611_spiekman_1.pdf
  31. 31. SOA / EDFA in 10Gb EPON 10Gb/s ONU 1 Gb/s Tx Booster PIN / 10Gb/s W W APD OLT EML SOA/ D PS D EDFA M M DML/ EML 10Gb/s Rx APD+EDC SOA Preamp Integrated Solution 10Gb/s ONU 1 Gb/s Tx PIN / 10Gb/s W W APD OLT EML SOA D PS D M M DML/ EML 10Gb/s Rx SOA APD+EDC Keep the ONU simple ! SOA may be used as data modulator
  32. 32. Fiber Non-linear Effect (SRS) 1490nm (pump) penalty 10G 1550nm (10G DS) 1. S. Tsuji, “Issues for wavelength allocation,” IEEE802.3av meeting, Sept. 2006 http://grouper.ieee.org/groups/802/3/av/public/2006_09/3av_0609_tsuji_1.pdf 2. S. Ten and M. Hajduczenia, “Raman-Induced power penalty in PONs using order approximation, IEEE802.3av meeting, Jan 2007, http://grouper.ieee.org/groups/802/3/av/public/2007_01/3av_0701_ten_2.pdf
  33. 33. Fiber Non-linear Effect (SBS) Limits transmitted power S. Ten, “SBS degradation of 10Gb/s digital signal in EPON: experiment and model” IEEE 802.3av meeting, Jan 2007 http://grouper.ieee.org/groups/802/3/av/public/2007_01/3av_0701_ten_1.pdf
  34. 34. WDM-PON S. Wagner et al, JOLT, 7, 1759 (1989) W CO D M • PS PON advantages • Subscriber buys upgrades – passive & future proof • Expensive components • Point-Point connections – WDM mux-demux cost still high – Privacy / Security – accurate wavelength lasers required • Simultaneous Service Diversity – temperature stability
  35. 35. Waveguide Grating Router INPUT OUTPUT 1 W 1 2 G 2 3 3 4 R 4 Remote I B1 B2 B3 Node user 1 Intensity I B1 B2 B3 B1 B2 B3 user 2 WGR ... I B1 B2 B3 user n • Also called Arrayed Waveguide Grating (AWG), phase array or Dragone Router • Fabricated on Silicon
  36. 36. WDM on WDM W W ... D G M R W ... D M + W ... D + M Ref: Iannone, et al., PTL 8, 930 (1996), Frigo, et al., OFC'97 PD24
  37. 37. Athermal AWG Devices
  38. 38. Athermal AWG
  39. 39. Injection Locking of Upstream Laser Spectrum before locking Courtesy: Novera Optics
  40. 40. Reflective SOA Courtesy of ETRI and Korea Telecom
  41. 41. Planar Lightwave Circuit - ECL Courtesy of ETRI and Korea Telecom
  42. 42. WE-PON (WDM-E-PON) ~ 1000 users per feeder fiber (32λ x 32 TDM) WDM-PON used for metro backhauling WDM is an efficient way to increase splitting ratio Courtesy of ETRI and Korea Telecom
  43. 43. Conclusion • Demands for bandwidth continue to drive broadband optical access network development – Digital and packetized video becomes the killer application – Bandwidth usage pattern is changing, statistical multiplexing no longer holds for new broadband applications (VoD) • FTTx – a personal view: – GPON delivers the right FTTH BW for the next a few years. – EPON offers the initial cost advantage • FTTx development is good for economy – 10GE-PON and WDM-PON developments will create new component industries • Don’t let our lack of imaginations limit the development of broadband access networks – FTTx research took 20 years to get to today’s deployment stage – Bandwidth is always good and will finds its applications to benefit human societies. • Question: Are there any other better ways to make a PON?
  44. 44. Thank you!

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