Recent Developments in PON Systems Standards in ITU-T

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Recent Developments in PON Systems Standards in
ITU-T

• Dave Faulkner
• Q2/15 Rapporteur
• dave.faulkner_at_bt.com

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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

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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.

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ITU-PON Access System
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Fixed Access Timelines
Fixed Access Timelines
Bit Rate
10G 1G 100M 10M 1M 100k 10k 1k
Source Next generation Broadband in Europe The
Need for Speed Heavy Reading Report, Vol. 3 No 5
March 2005 See Notes
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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)

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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

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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

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Business Drivers for PON
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Broadband PON Frame Format
Downstream Frame 56 cells of 53 bytes
PLOAM Cell 1
ATM Cell 1
ATM Cell 27
ATM Cell 27
PLOAM Cell 2
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)
ATM Cell 1
ATM Cell 2
ATM Cell 3
ATM Cell 53
3 overhead bytes for guard time, preamble and
delimiter
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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

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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

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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-303 H-D IPTV and optical RF Video
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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
  ONTs
• To receive additional service wavelength(s)
• e.g.

1480 1500
1539 1550 1565
-1.5
Receive
Accept
Reject
-20
-30 dBm
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ITU-PON Showcase at SUPERCOMM
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G-PON

• Gigabit Passive Optical Networks
• Higher capacities possible than B-PON
• More efficient transmission of IP/Ethernet Cells
• Same Optical Distribution Network

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Service Requirements for G-PON.
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Physical Layer Specifications for G-PON
2.4/1.2Gbit/s emerging as most popular rates
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Key Differences Between Gigabit- PONs
Item Item FSAN / ITU-T G-PON IEEE GE-PON
MAC Layer Service Full services (Ether, TDM, POTS) Ethernet data
MAC Layer Frame GEM frame Ethernet frame
PHY Layer Distance 10 / 20 km (Logical 60 km) 10 / 20 km
PHY Layer Branches 64 (Logical 128) 16 or over
PHY Layer Bit rate Up 155M, 622M, 1.25Gbit/s Down 1.25G, 2.5Gbit/s 1.25Gbit/s (Up and Down)
PHY Layer Bandwidth Same as above (NRZ coding) 1Gbit/s (8B10B coding)
PHY Layer Opt. Loss 15 / 20 / 25dB 15 / 20dB
PHY Layer Wave-length Down 1480-1500nm Up 1260-1360nm (Available to video signals overlay) Same
PHY Layer 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)
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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.

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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.

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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

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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.