ece 122-1st topic (1)

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Wired Communication Systems

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` Analog Telephony History

x A. Telegraphx Invented by Samuel F. B. Morse (1791-1872) in 1837

x Reduced the number of wires to onex Developed Morse code with the help of Alfred Vail and William

Baxter

x First Telephonex Alexander Graham Bell invented the first telephone in 1876

x Bell applied a patent for the first telephone on February 14,1876

x Bell¶s historic words were heard ³Mr . Watson, come here, I wantyou!

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x The beginning of telephony

x Convert diaphragm vibration into electrical energy

x Modulate a battery-driven, metallic circuits

x Converted back to sound waves at the distant end

x Business History

x Bell was financed by his wealthy industrialist father in-law, G.G. Hubbard

x Bell and Hubbard offered the patent to Western Union Telegraph

company for $100,000.00x $100,000.00 in the year 1876 has the same ³purchased power´ as

$1,667,910.09 in the year 2002

x The offer was turned down

x Bell Telephone company started on July 9, 1878

x

Promote telephone service throughout the U.S. On June 29, 1878x The Western Union Telegraph Company entered into the telephone

business in early 1878

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x Transmitters by Thomas Edison

x Receivers by Elisha Gray

x Bell Telephone Company sued Western Union for patent

infringementx The suit was settled in 1879

x Western Union acknowledged the validity of Bell¶s patent and agreedto stay out of the telephone business

x Bell Telephone Company abandoned interests in telegraph field

x

More than 6000 independents non-Bell telephone companiessprang up after Bell¶s patent expired in 1893 and 1894

x American Telephone and Telegraph ( AT & T) company became theparent company of Bell system in 1900

x They both aggressively attacked the independents

x They used separate subscribers which were unable to communicate

x Established long lines division providing long distance connectionbetween all cities

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x The federal government began regulating the telephone industry in1910

x Interstate Commerce Commission (ICC) oversaw all US wires and

radio communicationsx Communications Act in 1934

x The Federal Communications Commission (FCC) took over thetelephone industry

Still in charge of approving all interstate regulated activities in the

industry via tarriffsx Lower residential rates

x Raise cost of long distance service and business service

x AT & T virtually controlled all aspects of the telephone industry from1930¶s and 1950¶s

x 1914 ± ³Kingsbury Commitment´

x Divest its Western Union stock

x Stop buying up independent telephone companies, unlessauthorized by ICC

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x Allow the independents to interconnect to the AT&T network

- interconnections reduced the Bell¶s activity to drive theindependents out of business but also eliminated the

independent¶s incentive to establish a competitive long-distance system´

x 1956 Consent decree

x AT & T could retain ownership of Western Electric if it only producedproducts of Bell-operated companies

x

Prevent the Bell¶s system from offering commercial data processingservices

x Limit Bell System to providing telecommunication services under regulation

x Left Bell system a regulated monopoly with no competition for equipment and services in its operating areas

x 1968 Carterfone decisionx Allow subscribers to attach equipment to the network as long as it

was not ³publicly detrimental´

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x 1969 MCI (Microwave Communications Inc.) Decision

x Install and operate an interstate radio link between Chicago and St. Louis

x Lease private line services along this linkx Join the competition with AT & T

x Now known as Verizon

x 1984 Divestiture Agreement

x 23 Bell operating companies would be divested from the organization

of AT & Tx AT & T could pursue and operate in the competitive long-distance,

equipment manufacturing, and sales markets

- manufacturing later separated under the Lucent name

x The Telecom Act of 1996

x Beginning of the information superhighway

x New players compete for the local dial tone services

- in the US, dial tone amounts to a $90 to $100billion a year industry

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x Long distance companies enter into a new business opportunities

- dial tone

- cable TV services

- high-speed internet access- two-way video communications

x From 1996 to 2002 : spectacular business boom and bust due tobad forecasting and overbuilding

x Historically, US telephone usage grows roughly 3% a year

- second lines for internet and new mobile phones created10-15% growth during the mid 1990s

- internet was said to be doubling every 100 days andpoised to overtake one telephone network

- relaxed regulation allowed new competitors

forecast

actual

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x Suppliers and carriers borrowed and hired for huge growth

- second line boom stopped

- wired phone use is now decreasing

- wireless is growing, but more slowly than before- internet really grows 70-100% a year

- results: more than enough capacity

- prices are falling and usage is failing

- the loans come to the due date ± bankruptcy, more

lay offsx Different situation outside US: robust growth in Asia and Europe

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1900

Weak electric currents could operate a receiver at a distance More than 1000 miles over open wire About 200 miles on underground cable

1913 Vacuum-tube line amplifiers enabled speech to be transmitted

by longer distance

1915 Coast-to-coast long distance telephone connections wereestablished

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1927 Transatlantic radiotelephone service was introduced

1930¶s

J.R. Carson at Bell Laboratories developed FDM (FrequencyDivision Multiplexing) 12 conversations were conducted over two pairs of cable wires

1941 Coaxial cables were introduced to permit wideband transmission

of telephone signals

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1960¶s

Satellite

communicationsdeployed

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very long history : from 1876 to presentMany things are what they are due to whathappened in the past

Long-lived products and standardsPeer to peer communicationsHarder problems of compatibility,

connectivity, routing and congestion controlReliabilityExtreme and continuous

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ITU ± International TelecommunicationsUnion (a.k.a. CCITT)

- International standards and prevailing

local standards outside North America

ANSI- American National Standards Institute

- Sponsor T1 committee and other standards

- Carrier standards for North America

IETF ± Internet Engineering Task Force

- Internet protocol standards worldwide

- Produce high quality, relevant technical

documents that influence the way people

design, use and manage the internet

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Institute of Electrical and Electronics Engineers

-created several committees such as:

802 committee ± data communication standards

ECM A ± European Computer Manufacture

- Standards for computer equipment in Europe

Industry Forums:

ATM Forums, DSL Forums, etc..

- Manufacturers and carriers common positionsof equipment and standards

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Telcordia

-also known asBellcore

- Common standardsand procedures for

local carriers with U.S.

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The potential difference (voltage) across an idealconductor is proportional to the current through it

Determine the distance that signals could be sentwithout amplification

Ohm¶sLaw

The number of transistors that can fit onto a squareinch of silicon double every 12 months

Moore¶sLaw

The total bandwidth of communication systemstriples every 12 months

Gilder¶sLaw

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The value of a network is

proportional to the squareof the number of nodes The cost per user remains

the same or even reduces

Metcalfe¶sLaw

A

nything that can go wrongwill go wrong at the worstpossible time

Murphy¶sLaw

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ece 122-1st topic (1)

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