The document discusses the structure and components of the public switched telephone system. It covers topics like the local loop using technologies like modems, ADSL, and wireless; trunks connecting switching offices; switching offices; and multiplexing techniques like frequency division, wavelength division, and time division multiplexing used to increase bandwidth capacity on telephone lines. It also briefly mentions circuit switching, message switching, and packet switching network architectures.

1. LHDG / 2012A 1

2. LA RED TELEFONICA PUBLICA CONMUTADA
CONTENIDO
Introducción
Estructura del Sistema Telefónico
La política de los Teléfonos
El Cto. Local: modems, ADSL e Inalámbrico
Troncales y multiplexión
Conmutación
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3. LHDG / 2012A 3

4. Public Switched Telephone System
• Structure of the Telephone System
• The Politics of Telephones
• The Local Loop: Modems, ADSL and
Wireless
• Trunks and Multiplexing
• Switching
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5. Structure of the Telephone System
(a) Fully-interconnected network.
(b) Centralized switch.
LHDG / 2012A
(c) Two-level hierarchy. 5

6. Structure of the Telephone System (2)
A typical circuit route for a medium-distance call.
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7. Major Components of the Telephone System
• Local loops
 Analog twisted pairs going to houses
and businesses
• Trunks
 Digital fiber optics connecting the
switching offices
• Switching offices
 Where calls are moved from one trunk
to another
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8. The Politics of Telephones
The relationship of LATAs, LECs, and IXCs. All the
circles are LEC switching offices. Each hexagon
belongs to the IXC whose number is on it.
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9. The Local Loop: Modems,
ADSL, and Wireless
The use of both analog and digital transmissions for a
computer to computer call. Conversion is done by the
modems and codecs.
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10. Modems
(a) A binary signal (c) Frequency modulation
(b) Amplitude modulation (d) Phase modulation 10

11. Modems (2)
(a) QPSK.
(b) QAM-16.
(c) QAM-64.
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12. Modems (3)
(a) (b)
(a) V.32 for 9600 bps.
(b) V32 bis for 14,400 bps.
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13. Digital Subscriber Lines
Bandwidth versus distanced over category 3
UTP for DSL.
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14. Digital Subscriber Lines (2)
Operation of ADSL using discrete multitone
modulation.
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15. Digital Subscriber Lines (3)
A typical ADSL equipment configuration.
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16. Wireless Local Loops
Architecture of an LMDS system.
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17. Frequency Division Multiplexing
(a) The original bandwidths.
(b) The bandwidths raised in frequency.
LHDG / 2012A (b) The multiplexed channel. 17

18. Wavelength Division Multiplexing
Wavelength division multiplexing.
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19. Time Division Multiplexing
The T1 carrier (1.544 Mbps).
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20. Time Division Multiplexing (2)
Delta modulation.
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21. Time Division Multiplexing (3)
Multiplexing T1 streams into higher carriers.
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22. Time Division Multiplexing (4)
Two back-to-back SONET frames.
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23. Time Division Multiplexing (5)
SONET and SDH multiplex rates.
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24. Circuit Switching
(a) Circuit switching.
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(b) Packet switching. 24

25. Message Switching
(a) Circuit switching (b) Message switching (c) Packet switching 25

26. Packet Switching
A comparison of circuit switched and packet-
switched networks.
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