Recent Developments in PON Systems Standards in ITU-T

Dave FaulknerQ2/15 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

Downstream (single-fibre systems): 1490 nm ± 10 nm Upstream: 1310 nm ± 50 nm RF video (analogue, if present) 1555 nm ± 5 nm Maximum bit rate 2.488 Gb/s both downstream and upstream TDM Time Division Multiplex TDMA Time Division Multiple Access CC Cross Connect NB Narrow Band BB Broadband OLT Optical Line Termination ONT Optical Network Termination

TDMA

TDM

ONT

ONT

1:32 Optical splitter

0-20 km reach Optical Distribution Network

OLT

Access Node

NB

BB

CC

Video

Data

E1/T1/ Telephony

Data

E1/T1

GbE STMn/OCn

ONT

E1/T1/ Telephony

Fixed Access Timelines

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1990 1995 2000 2005 2010 2015 2020

Year

kbit

/s

18 M ADSL2plus20 M VDSL2 Cab

100 M VDSL2 DP

1 GBE

10 GBE

G-PON

WDM/PONWDM/PON

10 G-PON

8M ADSL

Investment/loss Region.Early introductionOf competitive technologyfor premium services

Profitable Region “Cash Cow”

Technology ‘uncompetitive’Migration to new technology

or loss of market share

56k modem

VDSL Plateau?

ADSL Plateau?

Source: “Next generation Broadband in Europe: The Need for Speed” Heavy Reading Report, Vol. 3 No 5 March 2005

See Notes

Bit Rate

10G

1G

100M

10M

1M

100k

10k

1k

Fixed Access Timelines

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– 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 PONBusiness factors

G.983.1

G.983.2International standards compliances and multi-vendor interoperability

G.983.5

G.983.6Access line protection and survivability

G.983.1amend1

G.983.1amend2

Adding 622Mb/s upstream

Adding 1.2Gb/s downstream and security

G.983.2amemd2Enhanced OMCI (ONT Management and Control Interface) for new services

G.983.4

G.983.7

DBA (Dynamic Bandwidth Assignment) to improve transmission efficiency of upstream signals

G.983.3

G.983.3amend1Video signal overlay with 3-waves multiplexing

ITU-T RecommendationB-PON Requirements

G.983.1

G.983.2International standards compliances and multi-vendor interoperability

G.983.5

G.983.6Access line protection and survivability

G.983.1amend1

G.983.1amend2

Adding 622Mb/s upstream

Adding 1.2Gb/s downstream and security

G.983.2amemd2Enhanced OMCI (ONT Management and Control Interface) for new services

G.983.4

G.983.7

DBA (Dynamic Bandwidth Assignment) to improve transmission efficiency of upstream signals

G.983.3

G.983.3amend1Video signal overlay with 3-waves multiplexing

ITU-T RecommendationB-PON Requirements

Competition with CLEC’sADSL

Competition with Long Haul operators

Competition with CATV providers

Economical and reliable products

Broadband PON Frame FormatDownstream Frame = 56 cells of 53 bytes

PLOAMCell 1

ATMCell 1

ATMCell 27

ATMCell 27

PLOAMCell 2

ATMCell 54

Physical layer operations and maintenance (PLOAM) cells give grants to upstream ONUs. Maximum rate of 1/100ms. Each contains 27 grants

ATMCell 1

ATMCell 2

ATMCell 3

ATMCell 53

Upstream Frame = 53 cells per frame (aligned by ranging)

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

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-303H-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.

Receive Accept Reject

1480 1500 1539 1550 1565

-1.5

-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.

Class A, B and C; same as B-PON requirementsODN classes

Downstream: 1480 – 1500nm (Video overlay is

Upstream: 1260 – 1360nm considered.)Wavelength allocation

Max 64 in physical layer

Max 128 in TC layerBranches

Max 60 km (for ranging protocol)Logical reach

Max 20 km and Max 10 kmPhysical reach

1.25Gb/s symmetric and higher

Asymmetric with 155Mb/s & 622Mb/s upstreamBit rates

Full Services

(e.g. 10/100Base-T, Voice, Leased lines)Services and QoSperformances

Target descriptionsItems

Class A, B and C; same as B-PON requirementsODN classes

Downstream: 1480 – 1500nm (Video overlay is

Upstream: 1260 – 1360nm considered.)Wavelength allocation

Max 64 in physical layer

Max 128 in TC layerBranches

Max 60 km (for ranging protocol)Logical reach

Max 20 km and Max 10 kmPhysical reach

1.25Gb/s symmetric and higher

Asymmetric with 155Mb/s & 622Mb/s upstreamBit rates

Full Services

(e.g. 10/100Base-T, Voice, Leased lines)Services and QoSperformances

Target descriptionsItems

Physical Layer Specifications for G-PON

LD*1 + PIN (APD*2 is available)

Up to 20km : DFB-LD or FP-LD with FEC

12Bytes (1.244Gbit/s), 24Bytes (2.488Gbit/s)Upstream Overhead

Optical device

Up to 10km : FP-LD without FECDispersion and error correction

1.244Gbit/s and 2.488Gbit/s symmetric

155.52Mbit/s and 622.04Mbit/s only for upstream

Error rate: Better than 1.0E-10

Bit rates

SpecificationItem

LD*1 + PIN (APD*2 is available)

Up to 20km : DFB-LD or FP-LD with FEC

12Bytes (1.244Gbit/s), 24Bytes (2.488Gbit/s)Upstream Overhead

Optical device

Up to 10km : FP-LD without FECDispersion and error correction

1.244Gbit/s and 2.488Gbit/s symmetric

155.52Mbit/s and 622.04Mbit/s only for upstream

Error rate: Better than 1.0E-10

Bit rates

SpecificationItem

2.4/1.2Gbit/s emerging as most popular rates

Key Differences Between Gigabit- PONsItem FSAN / ITU-T G-PON IEEE GE-PON

MACLayer

Service Full services (Ether, TDM, POTS) Ethernet data

Frame GEM frame Ethernet frame

PHYLayer

Distance 10 / 20 km (Logical: 60 km) 10 / 20 km

Branches 64 (Logical: 128) 16 or over

Bit rateUp : 155M, 622M, 1.25Gbit/sDown : 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-lengthDown : 1480-1500nmUp : 1260-1360nm(Available to video signals overlay)

Same

Upstream burst timing

Guard : 25.6nsPreamble : 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.