overview of the public switched telecommunications network (pstn)

Presented by Trevor R. Roycroft, Ph.D.2008 NASUCA Annual Meeting.November 17, 2008

Roycroft ConsultingEconomic and Policy Analysistrevor@roycroftconsulting.orgwww.roycroftconsulting.org508-896-0151 1

AT&T Bell system built a “nationwide” network to provide local and long distance services.

A “public switched” telecommunications network (PSTN).

Provided services at regulated rates on a “common carriage” basis.

Universal Service. Network capabilities

similar nationwide.

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DistributionAnd Drop(Copper TwistedPair)

FeederCopper orFiber

“Local Loop”Local SwitchTandem Switch

Local TransportCopper or Fiber

“Long Distance” Network (Fiber)


Mobile Telephone Switching Office



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Legacy PSTN Technology Deployment

The Internet revolution. Internet technology introduces:

Packet switching. A standardized communication platform,

delivering “best effort service.” No blocking. Transmission latency possible.

Potential for high bandwidth demand. How will the change affect the PSTN?

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Section 706 of the 1996 Act states: The Commission and each State commission with

regulatory jurisdiction over telecommunications services shall encourage the deployment on a reasonable and timely basis of advanced telecommunications capability to all Americans.

“advanced telecommunications capability' is defined, without regard to any transmission media or technology, as high-speed, switched, broadband telecommunications capability that enables users to originate and receive high-quality voice, data, graphics, and video telecommunications using any technology.”

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Competing platforms Cable Telephone company

RBOCs stick to their own turf. Overbuilders Wireless

RBOCs own largest wireless providers AT&T and Verizon purchased majority of 700 MHz spectrum WiMax on horizon?

Will competition ensure affordability? Will competition ensure universal access/service? Will competition deliver end-to-end compatible

technologies? Encourage benefits of network effects.

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DownstreamUpstream

FTTH

VDSL2

Cable Modem (DOCSIS 3.0)

Cable Modem (DOCSIS 2.0)

ADSL2+

WiMax

Basic DSL

Voice over Internet Protocol Relies on packet switching approach.

Uses broadband access network. Within the broadband access network, the

relative position of voice has changed. IPTV customer—200+ Gigabytes per month. Voice customer—less than 1 Gigabyte per

month.

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Largest telephone company. 35 million residential subscribers in 21 states. 75 million wireless subscribers. Have used DSL to deliver broadband.

“Fiber to the neighborhood” (FTTN). Utilizes existing copper distribution network. Shortens the copper run.

Typically enables 25 Mbps downstream, 1-3 Mbps upstream. Majority of bandwidth devoted to provision of U-verse

television. “IPTV” is used to compensate for limited overall

bandwidth.

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1010

Copper

Fiber replacesCopper

Local LoopOverhaul (FTTN)

Node

Set-Top Box

ResidentialGateway

HouseholdPhone CompanyCentral Office

FTTN pushes fiber deeper into the neighborhood to shorten the copper runs to 3,000 to 5,000 feet.

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IP Video Hub OfficesNational

IP Backbone

IP Video Super Hub

IP Serving Offices

CopperFiberFiber

Greenfield FTTP

Local LoopOverhaul (FTTN)

Node

Set-Top Box

ResidentialGateway

HouseholdHousehold

Low-bandwidth for data. Fiber deployments appear to be constrained for

marketing purposes to copper performance. “Pair-bonding” may double the capacity available,

but delivery of HD programming may command most of this additional bandwidth.

Competitive pressure on cable systems, which already beat U-verse Internet bandwidth with existing platform?

Structural discrimination against non-U-verse video? About 780,000 subscribers nationwide. 14 Million living units passed as of 3rd Quarter 2008.

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Second largest telephone company. 24.5 million residential subscribers in 29

states. 68 million wireless subscribers. Use both DSL and selective deployments of

fiber to the home (FTTH). FTTH provides a direct fiber optic

connection to the home. Replaces the copper wires in the network.

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FiOS

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FiOS

Optical Network Terminal

Optical Line

TerminalOptical

Couplers (WDM)

Voice & Data Downstream 1490 nm

Upstream 1310 nm

Voice, Data & Video 1490 nm, 1310 nm, 1550

nm

1x32

Optical Splitte

r

Video 1550 nm

CENTRAL

OFFICE CUSTOMER PREMISE

PSTN

Verizon IP Network

Verizon IP Network

InternetInternet

VideoHub

About 1.6 million FiOS TV customers nationwide.

About 2.2 million FiOS Internet customers nationwide.

Projects passing 12 million homes by year-end 2008.

Preferred technology, but limited to portions of Verizon’s service area.

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(1-year agreement)

PlansFiOS with existing Verizon phone service

FiOS without Verizon phone service

Up to 10 Mbps/2 Mbps $42.99/month $47.99/month



$139.95/month $144.95/monthUp to 50 Mbps/20 Mbps

Qwest has announced plans for a limited FTTN deployment. To pass 1.5 million homes by year-end

2008. Mixed signals regarding video plans.

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Will competition ensure affordability? Voice prices Broadband Internet access.

Will competition ensure universal access/service? AT&T v. Verizon v. Qwest

Will competition deliver end-to-end compatible technologies? Bandwidth differences impact application

development and innovation.

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ILECs don’t have to unbundle fiber. Copper retirement.

Strips a technology platform from the network.

DSL Ethernet over copper.

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USA

overview of the public switched telecommunications network (pstn)

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