This document discusses future access network technologies. It begins by introducing different access network architectures using copper or fiber connections to end users. The key criteria for designing access networks are meeting future bandwidth demands cost-effectively based on user forecasts. While copper remains an option if already deployed, fiber is more future-proof due to its vast bandwidth. Passive optical networks (PON) using fiber to the home/building are discussed as the most common fiber architecture. Different PON technologies like GPON, EPON, and upcoming WDM PON are summarized.

1. FUTURE OF WIRE-LINE
ACCESS NETWORKS
SEPTEMBER 2012
By Eng. Anuradha Udunuwara,
BSc.Eng(Hons), CEng, MIE(SL), MEF-CECP, MBCS, ITILv3 Foundation, MIEEE, MIEEE-CS, MIEE, MIET, MCS(SL), MSLAAS

2. Agenda
2
 Introduction
 Design Criteria
 Copper or fiber
 Optical access network
(c) Anuradha Udunuwara

3. Introduction
3
Wired (optical fiber) APON
Core
Wireless BPON
Wired (optical fiber) TDM PON
Aggregation GPON
Wireless
EPON
Cable PON
CSP networks
WDM PON
Wired
10GPON
Optical fiber
Access
AON
Copper Hybrid PON 10GEPON
Wireless
(c) Anuradha Udunuwara

4. Design Criteria
4
 Start with some forecasted marketing data.
 The networks that we build today should be future proof as far as possible in terms of service demand and
technology used.
 Example: for a residential triple play access network, it is better to have some figure on the number of customers per area, type of
services required by those customers, the bandwidths consumed for each service and the bandwidth per house hold. Based on this
information, we can find out the immediate bandwidth requirement per customer and the future demand.
 Fiber is able to carry large amounts of data. Optical fiber networks in that sense are very much future
proof.
 It is always a good idea to design the networks for your real requirement rather than going behind various
technologies. A technology used in United States or Europe may not be able to directly deployed in
countries like ours.
 Main decision factors when deciding on an access network technology/media;
 cost per user
 bandwidth demand
 demographic criteria.
 Current trend is to deliver more bandwidth per user in a secure way at lower cost.
(c) Anuradha Udunuwara

5. Copper or fiber ?
5
 If copper is already laid and available to the households, then it will be a good idea to use
them if the required bandwidths can be delivered using them.
 Fundamental problem of copper based access is the decaying of speed with the distance.
Most of today’s copper based access networks start from the central office (CO) of the SP
and goes to the customer. The access network is fully passive, consisting of, but not limited to,
Main Distribution Frame (MDF), primary cable, Cabinet, secondary cable, Distribution Point
(DP) and overhead cable. The popular Digital Subscriber Line (DSL) technologies are
struggling to deliver high bandwidths when the distance between the CO and the customer
increases.
 One solution is to use optical fiber, instead of copper. While it is accepted that the ideal
solution is to have fiber, we can also try to shorten the copper length and deliver high
bandwidths. This will save lot of cost as fiber is not freshly drawn. This introduces a new term
called FTTX, Fiber To The “place you want”. X could be building, home, curb/cabinet, node or
even desk. So now the issue is between FTTH and FTTC/B.
(c) Anuradha Udunuwara

6. Optical access networks
6
 Optical access networks could be active or passive. An example of an Active Optical Network (AON) is
Metro Ethernet or Carrier Ethernet. Here, active Ethernet switches are deployed in the network to deliver
services, mainly to business customers. The networks mostly take the form of rings assuring high availability
required by business critical applications.
 The other category is Passive Optical Networks (PON). PON works by delivering an end to end fiber
access to the building or home. Though PON can be used for FTTC/N applications, most PON applications
are based on FTTH/B architecture. Unlike AON, PON can not have any protection in the last mile, because
of its passive nature. PON works by dividing an optical signal into multiple fibers using a passive optical
splitter. After the splitter, the network is liner and does not provide any direct protection. This type of a
solution is mainly suitable for a residential rather than business.
 TDM PON is the current choice because of its low cost. Out of the available TDM PON technologies, GPON
has much better multi service capabilities and carrier grade management capabilities and therefore the
winning technology. It is also future proof, because of its high bandwidth support.
(c) Anuradha Udunuwara

7. Options
TDM PON
ATM PON (APON) Ethernet PON (EPON) Gigabit PON (GPON) WDM PON Hybrid TDM / WDM
=Broadband PON(BPON) = Gigabit Ethernet PON PON
7
=A/B PON (GEPON )
ITU-T G.983 standard IEEE 802.3ah standard ITU-T G.984 standard
Developed from Telco side Developed from Internet Evolved from A/B PON Evolution from TDM
side PON
Layer 2 encapsulations Layer 2 encapsulation is L2 encapsulations are
are Ethernet and Ethernet GEM(GPON
Asynchronous Transfer Encapsulation Method) for
Mode (ATM) Ethernet and ATM Still at research stage
Maximum up stream is Maximum up stream and Maximum up stream and Maximum up stream
155Mbps, Maximum downstream is 1.25Gbps downstream is 2.5Gbps and downstream is 10
downstream is 622Mbps Gbps
Deployments: US (ex: Deployments: Japan (ex: Deployments: US (ex: Deployments: Korea
Verizon FiOS) NTT, KDDI), Korea (ex: KT), AT&T), Europe (ex: KT), China
China, India
(c) Anuradha Udunuwara

8. About the Author
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Eng. Anuradha Udunuwara is a Chartered Engineer by profession based in Sri Lanka. He has nearly a decade
industry experience in strategy, architecture, engineering, design, plan, implementation and maintenance of CSP
Networks using both packet-switched (PS) and Circuit-Switched (CS) technologies, along with legacy to NGN
migration. Eng. Anuradha is a well-known in the field of CSP industry, both locally and internationally.
Graduated from University of Peradeniya, Sri Lanka in 2001 with an honors in Electrical & Electronic Engineering,
Eng. Anuradha is a corporate member of the Institution of Engineers Sri Lanka, a professional member of British
Computer Society, a member of Institution of Electrical & Electronic Engineers, a member of Institution of
Engineering & Technology (formerly Institution of Electrical Engineers), a member of the Computer Society of Sri
Lanka, a life member of Sri Lanka Association for the Advancement of Science, senior member of the Carrier
Ethernet Forum, member of the Internet Society, member of the Internet Strategy Forum, member of the Internet
Strategy Forum Network, member of the Ethernet Academy, member of the NGN/IMS forum and member of the
Peradeniya Engineering Faculty Alumni Association. He is also an ITIL foundation certified and the only MEF-CECP in
the country.
In his spare time Anuradha enjoys spending time with his family, playing badminton, photography, reading and
travelling.
He can be reached at udunuwara@ieee.org
(c) Anuradha Udunuwara