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Using Telephone and Cable Networks for Data Transmission
Semester: 131 Course: CSET 221 Computer Networking Instructor: Farhan Khan Computer Science & Engineering Technology Unit Hafr Al-Batin Community College
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Outline Telephone lines Dial-up modems Digital Subscriber Line (DSL)
Cable TV networks
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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
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Telephone Line Bandwidth
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stands for modulator/demodulator.
Dial-Up Modems Modem stands for modulator/demodulator.
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56K Modems
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Topics discussed in this section:
Digital Subscriber Line (DSL) After traditional modems reached their peak data rate, telephone companies developed another technology, DSL, to provide higher-speed access to the Internet. Digital subscriber line (DSL) technology is one of the most promising for supporting high-speed digital communication over the existing local loops. Topics discussed in this section: ADSL ADSL Lite HDSL SDSL VDSL
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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
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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
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ADSL is an asymmetric communication technology designed for residential users; it is not suitable for businesses.
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The existing local loops can handle bandwidths up to 1.1 MHz
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ADSL is an adaptive technology. The system uses a data rate
based on the condition of the local loop line.
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Bandwidth Division in ADSL
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Discrete Multi-Tone Modulation
Or DMT
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Bandwidth Division 4Khz
Allocation and modulation of each channel are determined adaptively
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Bandwidth Division 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 224 data channels, 1 control channel 13.4 Mbps (max) downstream bit rate Actual bit rate: 500 Kbps to 8 Mbps
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ADSL Customer Residence
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DSL Access Multiplexer
Or DSLAM
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Other DSL Technologies
HDSL – High-bit-rate DSL SDSL – Symmetric DSL VDSL – Very-high-bit-rate DSL ADSL2 ADSL2+ See also Source: AWARE. ADSL2 and ADSL2+ The new ADSL standard.
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Table 9.1 Summary of DSL technologies
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Topics discussed in this section:
Cable TV Networks The cable TV network started as a video service provider, but it has moved to the business of Internet access. In this section, we discuss cable TV networks; in next Section we discuss how this network can be used to provide high-speed access to the Internet. Topics discussed in this section: Traditional Cable Networks Hybrid Fiber-Coaxial (HFC) Network
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Cable TV Networks Started as a video service provider, then moved to the business of Internet access Communication is simplex
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Communication in the traditional cable TV network is unidirectional.
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Hybrid Fiber-Coaxial Network
Or HFC Bidirectional communication is achieved
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Communication in an HFC cable TV network can be bidirectional.
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Topics discussed in this section:
Cable TV for Data Transfer Cable companies are now competing with telephone companies for the residential customer who wants high-speed data transfer. In this section, we briefly discuss this technology. Topics discussed in this section: Bandwidth CM and CMTS
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Division of Coaxial Cable Band by CATV
Downstream Video Band can accommodate more than 80 channels. Each TV channel occupies 6 MHz Theoretical downstream data rate is 30 Mbps Theoretical upstream data rate is 12 Mbps
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Downstream data are modulated using the QAM modulation technique.
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The theoretical downstream data rate is 30 Mbps.
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Upstream data are modulated using the QPSK modulation technique.
Note Upstream data are modulated using the QPSK modulation technique.
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The theoretical upstream data rate is 12 Mbps.
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Cable Modem (CM)
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Cable Modem Transmission System
Or CMTS
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Summary Telephone lines Dial-up modems Digital Subscriber Line (DSL)
Cable TV networks
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