1. Recent Developments in PON Systems Standards in ITU-T
Dave Faulkner
Q2/15 Rapporteur

2. 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

3. The Role of the ITU in Standardization
The International Telecommunication Union (
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.

4. ITU-PON Access System

5. 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

6. 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)

7. 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

8. 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

9. Business Drivers for PON

10. 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 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

11. 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

12. 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

13. 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

14. G.983.3 Enhancement Band Downstream bands for B-PON
1490 (basic band) , 1550 (enhancement band)
New laser was required for nm band
Enhanced services in nm band
e.g. for broadcast services
nm upstream band retained
Blocking filters and/or triplexer needed for ONT’s
To receive additional service wavelength(s)
e.g.
Receive
-1.5
Accept
Reject
nm=nanometers
-20
-30 dBm

15. ITU-PON Showcase at SUPERCOMM

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

17. Service Requirements for G-PON.

18. Physical Layer Specifications for G-PON
2.4/1.2Gbit/s emerging as most popular rates

19. 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 : nm
Up : nm
(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)

20. Recent Updates to B-PON standards
Nov 2004
G Revised. ‘Broadband Optical Access Systems Based On Passive Optical Networks (PON)’
Includes two previous Amendments, A Corrigendum, and Implementers’ guide
G 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 Revised ‘B-PON ONT Management and Control Interface (OMCI)’.
All documents on OMCI have been merged into this revision, G and G through to G plus the Amendments 1 and 2 and Implementers’ guide.
New functionality includes mechanized loop testing for telephony and ‘last gasp’ reporting
G 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 Amendment 1 on Protocol Implementation Conformance Statements (PICS) for the OLT and ONT.
To show that the devices conform with G at the transmission convergence layer

21. Recent Updates to G-PON standards
May 2005
G 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 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.

22. 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

23. 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.