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Recent Developments in PON Systems Standards in ITU-T Dave Faulkner Q 2/15 Rapporteur dave. [email protected] com
Contents • • • The Role of the ITU in Standardization ITU-PON Access System Fixed Access Timelines Fiber Access Systems B-PON G-PON Recent Updates to B-PON and G-PON standards Outlook Conclusions
The Role of the ITU in Standardization • The International Telecommunication Union (www. itu. int), – headquartered in Geneva, Switzerland, – within United Nations System – governments and the private sector members coordinate global telecom networks and services. – ITU-T Recommendations, such as G. 982 (PON), G. 983. x (Broadband. PON) and G. 984. x (Gigabit-PON) are agreed by consensus and provide a framework for the implementation. – Question 2 on “Optical systems for fiber access networks” is the focus of activity for PON systems in the ITU • From an operator's perspective, cost reduction is the key motivator for standards – Interoperability and second sourcing are also important for a de-risking the investment. • From a vendor's perspective it is the assurance that products will satisfy the needs of a world-wide market.
ITU-PON Access System
Fixed Access Timelines 10 G 1 G 100 M Bit 10 M Rate Investment/loss Region. 10 GBE Early introduction 1 GBE Of competitive 10 G-PON technology G-PON 100 M VDSL 2 DP for premium 20 M VDSL 2 Cab services 18 M ADSL 2 plus 8 M ADSL 1 M 100 k 56 k modem 10 k WDM/PON VDSL Plateau? ADSL Plateau? Profitable Region “Cash Cow” Technology ‘uncompetitive’ Migration to new technology or loss of market share 1 k Source: “Next generation Broadband in Europe: The Need for Speed” Heavy Reading Report, Vol. 3 No 5 March 2005 See Notes
Fiber Access Systems. BT Perspective • Fiber to the premises (P 2 P, from CO) – – Existing deployment for businesses over 3 km and 2 Mbit/s Incremental deployment has high cost and long ‘lead’ times Churn leads to stranded assets Duct network insufficient for ubiquitous coverage • While copper stays in place • Fiber to the cabinet/VDSL 2 – – In BT trials Reuse of copper offers lower Cap. Ex than FTTP Op. Ex costs under investigation in trials Capacity is reach dependent • Subtended MSANs or Fiber could solve this • CO fed fibers are most likely to be used • Fiber to the premises (PON) – G-PON (e. g. 2. 4/1. 2 Gbit/s), favoured for limited use in 21 CN – Lower Cap. Ex and Op. Ex than (P 2 P) if deployed over whole areas – PON/OLT can act as a traffic concentrator (Qo. S, possible)
Active Optical Networks (P 2 P from COs/Cabs) - an alternative to PON • AONs deployed in parts of Europe by CLECs, approx 500 k subscribers • P 2 P can give more capacity than shared access systems – Better future-proofing • Upgrades – Only affect one customer – Require no changes to external plant • Shared access systems seem to date quickly – E. g. Cable systems are difficult to upgrade, outside plant needs changing – Shared access not needed with SDV (no broadcasting needed now) • Service and Network Management is a concern for operators/standards – Except SDH when used for direct connection to customers – G. 985 adds limited network management functionality to Ethernet over fiber
B-PON • Broadband passive optical network – – – based upon 53 byte ATM cells with mini-cells in transmission convergence (TC) layer Downstream ‘grants’ control the sending of upstream cells Rates up to 620 Mbit/s symmetrical • and 1240/622 asymmetrical have been standardised • Transport capability – – – native ATM TDM (T 1/E 1) by circuit emulation Ethernet by emulation • Business or home – 32 way split (some systems 64 way) – multi-casting possible • Standardised in G 983. x series in ITU
Business Drivers for PON
Broadband PON Frame Format Downstream Frame = 56 cells of 53 bytes PLOAM ATM Cell 1 ATM PLOAM ATM Cell 27 ATM Cell 54 Physical layer operations and maintenance (PLOAM) cells give grants to upstream ONUs. Maximum rate of 1/100 ms. Each contains 27 grants Upstream Frame = 53 cells per frame (aligned by ranging) ATM Cell 1 ATM Cell 2 ATM Cell 3 3 overhead bytes for guard time, preamble and delimiter ATM Cell 53
ONU Management and Control Interface • A management channel between OLT and ONU – Part of the baseband signal – Carried in the PLOAM cells • Physical layer operations and maintenance – Accessible by the Network Operator via the element manager on the OLT – Allows the PON and services to be configured and managed • Authentication, configuration and fault mangnet • Service management POTS, Video on demand, WLAN, VLAN, Ethernet – etc
Dynamic Bandwidth Allocation • A powerful conditional access mechanism – allows queues at the customer-ends of the PON to be served according to the priority assigned to the traffic flow – ranging from TDM circuit emulation through to best effort (using spare capacity). – also offers 'concentration on the fly', • statistical gain for packet-based services – likely to become increasingly important as users of IP begin to expect Qo. S-based services on congested networks • Allows bursts close to the maximum PON rate • Good for high speed packet transmission
B-PON Interoperability Events Where When Host Functionality Makuhari, Japan March 9 -11, NTT/FSAN meeting TC layer with Ethernet 2004 Geneva, Switzerland June 2 -4, 2004 ITU ‘All Star Workshop’ San Ramon, CA, USA Sept 27, 2004 SBC/FSAN meeting TC Layer with Ethernet Voice and fax services via GR-303 Chicago, USA June 7 -9, 2005 TIA/ITU, SUPERCOMM TC Layer with Ethernet Voice service via GR-303 H-D IPTV and optical RF Video
G. 983. 3 Enhancement Band • Downstream bands for B-PON – 1490 (basic band) , 1550 (enhancement band) • New laser was required for 1480 -1500 nm band • Enhanced services in 1539 -1565 nm band – e. g. for broadcast services • 1260 -1360 nm upstream band retained • Blocking filters and/or triplexer needed for ONT’s – To receive additional service wavelength(s) – e. g. 1480 1500 1539 1550 Receive -1. 5 Accept -20 Reject -30 d. Bm 1565
ITU-PON Showcase at SUPERCOMM
G-PON • Gigabit Passive Optical Networks – Higher capacities possible than B-PON – More efficient transmission of IP/Ethernet Cells – Same Optical Distribution Network
Service Requirements for G-PON.
Physical Layer Specifications for G-PON 2. 4/1. 2 Gbit/s emerging as most popular rates
Key Differences Between Gigabit- PONs Item FSAN / ITU-T G-PON IEEE GE-PON Full services (Ether, TDM, POTS) Ethernet data Frame GEM frame Ethernet frame 10 / 20 km (Logical: 60 km) 10 / 20 km Branches 64 (Logical: 128) 16 or over Bit rate Up : 155 M, 622 M, 1. 25 Gbit/s Down : 1. 25 G, 2. 5 Gbit/s 1. 25 Gbit/s (Up and Down) Bandwidth PHY Layer Service Distance MAC Layer Same as above (NRZ coding) 1 Gbit/s (8 B 10 B coding) Opt. Loss 15 / 20 / 25 d. B 15 / 20 d. B Wave-length Down : 1480 -1500 nm Up : 1260 -1360 nm Same (Available to video signals overlay) Upstream burst timing Guard : 25. 6 ns Preamble : 35. 2 ns (Typical) Delimiter : 16. 0 ns (Typical) Laser turn on / off : 512 ns (Max) AGC setting and CDR lock : 400 ns (Max)
Recent Updates to B-PON standards • Nov 2004 • G. 983. 1 Revised. ‘Broadband Optical Access Systems Based On Passive Optical Networks (PON)’ – Includes two previous Amendments, A Corrigendum, and Implementers’ guide • G. 983. 2 Amendment 2, ‘B-PON ONT Management and Control Interface (OMCI) support for Video Return Path’, – Facilitates the use of set-top boxes originally designed for cable networks • May 2005 • G. 983. 2 Revised ‘B-PON ONT Management and Control Interface (OMCI)’. – All documents on OMCI have been merged into this revision, G. 983. 2 and G. 983. 6 through to G. 983. 10 plus the Amendments 1 and 2 and Implementers’ guide. – New functionality includes mechanized loop testing for telephony and ‘last gasp’ reporting • G. 983. 3 Amendment 2, “A broadband optical access system with increased service capability by wavelength allocation” – Industry best practice optical budgets for the 622/155 B-PON system • • 28 d. B Optical Distribution Networks for B-PON 27 d. B with Analog video service • G. 983. 1 Amendment 1 on Protocol Implementation Conformance Statements (PICS) for the OLT and ONT. – To show that the devices conform with G. 983. 1 at the transmission convergence layer
Recent Updates to G-PON standards • May 2005 • G. 984. 3 Amendment 1 to G-PON Transmission Convergence Layer. – Peak Information Rate and Sustained Information Rate parameters are now included and are analogous to ATM for alternative cell lengths such as Ethernet packets. – Multicast services may now be supported over GEM (e. g. IPTV). – (GEM is the generic encapsulation mode use at in the transmission convergence layer) • G. 984. 4 Amendment 1 “Gigabit-capable Passive Optical Networks (G-PON): ONT Management and Control Interface specification”. – Proposes management features on G-PON in support of Ethernet and IPTV service such as the IEEE 802. 1 p priority mapper, GEM traffic descriptor, and support of multicast connection.
Outlook • Capacity doubling every year! – 1000 -fold increase in 10 years. – depends upon investment in new infrastructure, – Varies between country, region and location • Dependent on the economics and national strategy. • Can the life of G-PON be extended? – Bursting to 1 Gbit/s could buy 3 years (to 2016) • Upgrades – With the addition of new wavelengths and/or new fiber – Faster TDM-10 Gbit/s – WDM/PON
Conclusions • The B-PON and G-PON series of standards are largely complete – B-PON has reached maturity with up to eight vendors with interoperable OLT and/or ONU. – The FSAN/Interoperability Task Group promotes standards conformance and interoperability among vendors. • Recommendations in the G. 984. x series detail G-PON, the latest generation of PON technology. – Increasing capacity to Gigabit levels satisfies customer demands for capacity in the range 100 Mbit/s (dedicated) and 1 Gbit/s (shared) – G-PON maintains the same optical distribution network, wavelength plan as B-PON • offers more efficient IP and Ethernet handling • Next step is G-PON interoperability • The enhancement band is used by some operators to transport analog cable TV – In the future, as TV moves from RF-analogue to digital-in-band the enhancement band is expected to be used for two-way interactive digital services.