Recent Developments in PON Systems Standards in ITU-T Dave Faulkner Q2/15 Rapporteur dave.faulkner@bt.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 18 M ADSL2plus 20 M VDSL2 Cab 100 M VDSL2 DP 1 GBE 10 GBE G-PON WDM/PON 10 G-PON 8M ADSL Investment/loss Region. Early introduction Of competitive technology for premium services Profitable Region “Cash Cow” Technology ‘uncompetitive’ Migration to new technology or loss of market share 56k modem VDSL Plateau? ADSL Plateau? Bit Rate 10G 1G 100M 10M 1M 100k 10k 1k Hong Kong Broadband Network already offers 1Gbit/s access to residential users and BT offers an SHDS system now. There are substantial deployments of 100 Mbit/s access systems in some countries (e.g. Sweden, The Netherlands) Les Humphrey (BT/DSL ITU rep) comment “Historical speed increase are based upon reuse of existing lines and minimal investment in infrastructure. VDSL and fiber will require large investments in infrastructure which is likely to slow up the rate of increase”. Price declines with speed increases mean that the turnover is likely to remain static. Some value-add can be expected if a new ‘killer’ service emerges. 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 (P2P, from CO) Existing deployment for businesses over 3km 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/VDSL2 In BT trials Reuse of copper offers lower CapEx than FTTP OpEx 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 21CN Lower CapEx and OpEx than (P2P) if deployed over whole areas PON/OLT can act as a traffic concentrator (QoS, possible)

Active Optical Networks (P2P from COs/Cabs) - an alternative to PON AONs deployed in parts of Europe by CLECs, approx 500k subscribers P2P 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 Transport capability 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 (T1/E1) by circuit emulation Ethernet by emulation Business or home 32 way split (some systems 64 way) multi-casting possible Standardised in G983.x series in ITU

Business Drivers for PON

Broadband PON Frame Format Downstream Frame = 56 cells of 53 bytes PLOAM Cell 1 ATM Cell 1 ATM Cell 27 PLOAM Cell 2 ATM Cell 27 ATM Cell 54 Physical layer operations and maintenance (PLOAM) cells give grants to upstream ONUs. Maximum rate of 1/100ms. Each contains 27 grants Upstream Frame = 53 cells per frame (aligned by ranging) The encryption algorithm recommended is the Advanced Encryption Standard (AES). It is a block cipher that operates on 16 byte (128 bit) blocks of data. It accepts 128, 192, and 256 byte keys. This algorithm is described in documents published by the National Institute of Standards and Technology (NIST) in the USA. Normal ranging procedure. The maximum round-trip delay of about 200 µs (equal to 20 km optical fiber) is equal to 69 cells (56 byte-cells), so the equalization delay at the ONU should cover the delay variation from 0 to 32 000 bits (at 155.52 Mbit/s). Before initiating the ranging process, the OLT sends an Upstream overhead message to indicate to new ONUs which overhead they have to use. Then the OLT initiates the ranging process. The upstream data grants are queued. After the ranging grant leaves the OLT, an upstream window is opened to receive a ranging PLOAM cell. The additional ranging grants or PLOAM grants, allow the ONU optical power set-up and/or the OLT threshold control or amplitude finding etc. ATM Cell 1 ATM Cell 2 ATM Cell 3 ATM Cell 53 3 overhead bytes for guard time, preamble and delimiter

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 QoS-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, 2004 NTT/FSAN meeting TC layer with Ethernet Geneva, Switzerland June 2-4, 2004 ITU ‘All Star Workshop’ TC Layer with Ethernet San Ramon, CA, USA Sept 27, 2004 SBC/FSAN meeting Voice and fax services via GR-303 Chicago, USA June 7-9, 2005 TIA/ITU, SUPERCOMM 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 1565 Receive -1.5 Accept Reject nm=nanometers (10@-9) -20 -30 dBm

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 2.4/1.2Gbit/s emerging as most popular rates

Key Differences Between Gigabit- PONs Item FSAN / ITU-T G-PON IEEE GE-PON MAC Layer Service Full services (Ether, TDM, POTS) Ethernet data Frame GEM frame Ethernet frame PHY Distance 10 / 20 km (Logical: 60 km) 10 / 20 km Branches 64 (Logical: 128) 16 or over Bit rate Up : 155M, 622M, 1.25Gbit/s Down : 1.25G, 2.5Gbit/s 1.25Gbit/s (Up and Down) Bandwidth Same as above (NRZ coding) 1Gbit/s (8B10B coding) Opt. Loss 15 / 20 / 25dB 15 / 20dB Wave-length Down : 1480-1500nm Up : 1260-1360nm (Available to video signals overlay) Same Upstream burst timing Guard : 25.6ns Preamble : 35.2ns (Typical) Delimiter : 16.0ns (Typical) Laser turn on / off : 512ns (Max) AGC setting and CDR lock : 400ns (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 28dB Optical Distribution Networks for B-PON 27dB 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 IEEE802.1p 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 1Gbit/s could buy 3 years (to 2016) Upgrades With the addition of new wavelengths and/or new fiber Faster TDM-10Gbit/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.