Telephone (kỹ THUẬT TRUYỀN số LIỆU SLIDE)

Using Telephone and Cable Networks for Data Transmissions... Telephone Lines  Traditional telephone lines can carry frequencies between 300 and 3300 Hz  Giving them a bandwidth of 3000

Using Telephone and Cable Networks

for Data Transmissions

Telephone Lines

 Traditional telephone lines can carry frequencies between 300 and 3300 Hz

 Giving them a bandwidth of 3000 Hz

 All this range is used for transmitting voice

 A great deal of interference and distortion can be accepted without loss of intelligibility

Telephone Line Bandwidth

V.32 and V.32bis

56K Modems

Digital Subscriber Line (DSL)

 Provides higher-speed access to the Internet

 Supports high-speed digital communication over the existing local loops

 The existing local loops can handle bandwidths up to 1.1 MHz

ADSL

 ADSL – Asymmetric Digital Subscriber Line

 Downstream bit rate > upstream bit rate

 Designed for residential users

 Unsuitable for businesses

 ADSL operates on existing local loops

 Local loops can handle up to 1.1 MHz of bandwidth

 The distance limit is ~18,000 feet

 The system uses a data rate based on the condition of the local loop line

Bandwidth Division in ADSL

Discrete Multi-Tone Modulation

 Or DMT, based on OFDM (Orthogonal Frequency-Division

Multiplexing) technique

 Voice – Channel 0

 Idle – Channels 1-5

 Upstream – Channels 6-30

 24 data channels, 1 control channel

 1.44 Mbps (max) upstream bit rate

 Actual bit rate: 64 Kbps to 1 Mbps

 Downstream – Channels 31-255

 224 data channels, 1 control channel

 13.4 Mbps (max) downstream bit rate

 Actual bit rate: 500 Kbps to 8 Mbps

Bandwidth Division

ADSL Customer Residence

DSL Access Multiplexer

 Or DSLAM

 Orthogonal Frequency-Division Multiplexing

 Widely used in wideband digital communications

OFDM Concept

 Sub-carriers are orthogonal to each other

 No cross-talk; guard bands not necessary

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Source: http://connectedplanetonline.com

Data Transfer over CATV

Cable Modem

Cable Modem Transmission System

 Or CMTS

Fiber To The X

 Optical broadband network architectures

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Fiber-to-the-Source: Wikipedia

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