9.1
Chapter 9
Using Telephoneand Cable Networks
for Data Transmission
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
9.2
9-1 TELEPHONE NETWORK9-1 TELEPHONE NETWORK
Telephone networks use circuit switching. The Telephone networks use circuit switching. The telephone network had its beginnings in the late telephone network had its beginnings in the late 1800s. The entire network, which is referred to as the 1800s. The entire network, which is referred to as the plain old telephone systemplain old telephone system ( (POTSPOTS), was originally an ), was originally an analog system using analog signals to transmit voice.analog system using analog signals to transmit voice.
Major ComponentsLATAs: Local Access Transport AreasSignalingServices Provided by Telephone Networks
Topics discussed in this section:Topics discussed in this section:
9.3
Figure 9.1 A telephone system
Endoffices
Local loop
Trunk
Tandemoffices Regional offices
Trunk
• • •
9.4
Intra-LATA services are provided by local exchange carriers.
Since 1996, there are twotypes of LECs: incumbent local
exchange carriers and competitive local exchange carriers.
9.5
Service between LATAs are handled by Ineterexchange carriers (IXC) services are provided by long distance company.
POP; Point of presence: Each IXC that wants to provide inter-LATA services in a LATA must have a POP in that LATA
The local exchange carrier that provides services in that LATA must provide all its customers connections to access all POPs
9.8
The tasks of data transfer and signaling are separated in modern telephone
networks: data transfer is done by one network, signaling by another.
SS7: Signaling System Seven is the protocol used in the signaling network
Note
9.11
9-2 DIAL-UP MODEMS9-2 DIAL-UP MODEMS
Traditional telephone lines can carry frequencies Traditional telephone lines can carry frequencies between 300 and 3300 Hz, giving them a bandwidth of between 300 and 3300 Hz, giving them a bandwidth of 3000 Hz. All this range is used for transmitting voice, 3000 Hz. All this range is used for transmitting voice, where a great deal of interference and distortion can where a great deal of interference and distortion can be accepted without loss of intelligibility.be accepted without loss of intelligibility.
Modem StandardsTopics discussed in this section:Topics discussed in this section:
9.13
Modemstands for modulator/demodulator.
V.32, V.32bis, V90, V.92: ITU-T standardsV.32: 14,400 bps (7 bits with 1 bit for
error at a rate of 2400 baudV.90: also called 56K modems( 8bits with 1 bit for error at a rate of 8000):
Upload has a max of 33.3kbpsDownload has a max of 56kbps
V.92: Upload at 48Kbps with features such a call-waiting.
9.17
9-3 DIGITAL SUBSCRIBER LINE9-3 DIGITAL SUBSCRIBER LINE
After traditional modems reached their peak data rate, After traditional modems reached their peak data rate, telephone companies developed another technology, telephone companies developed another technology, DSL, to provide higher-speed access to the Internet. DSL, to provide higher-speed access to the Internet. Digital subscriber lineDigital subscriber line ( (DSLDSL) technology is one of the ) technology is one of the most promising for supporting high-speed digital most promising for supporting high-speed digital communication over the existing local loops. communication over the existing local loops.
ADSLADSL LiteHDSLSDSLVDSL
Topics discussed in this section:Topics discussed in this section:
9.18
ADSL is an asymmetric communication technology designed for residential
users; it is not suitable for businesses.
9.19
The existing local loops can handle bandwidths up to 1.1 MHz with a
filter( 4Khz bandwidth) for voice devices
Note
9.20
ADSL is an adaptive technology. The system uses a data ratebased on the condition of
the local loop line.
Note
9.22
Upstream: Uses 25 channels (6 to 30), 1 signal, 24 data.
24 x 4000 x 15 = 1.44Mbps. Practically some channels are not used: only
500Kbps, Downstream: 225 channels (31-255), 1
for control 224 x 4000x 15 = 13.4Mbps Practically: 8Mbps
9.27
9-4 CABLE TV NETWORKS9-4 CABLE TV NETWORKS
The The cable TV networkcable TV network started as a video service started as a video service provider, but it has moved to the business of Internet provider, but it has moved to the business of Internet access. In this section, we discuss cable TV networks access. In this section, we discuss cable TV networks per se; in Section 9.5 we discuss how this network can per se; in Section 9.5 we discuss how this network can be used to provide high-speed access to the Internet.be used to provide high-speed access to the Internet.
Traditional Cable NetworksHybrid Fiber-Coaxial (HFC) Network
Topics discussed in this section:Topics discussed in this section:
9.32
9-5 CABLE TV FOR DATA TRANSFER9-5 CABLE TV FOR DATA TRANSFER
Cable companies are now competing with telephone Cable companies are now competing with telephone companies for the residential customer who wants companies for the residential customer who wants high-speed data transfer. In this section, we briefly high-speed data transfer. In this section, we briefly discuss this technology.discuss this technology.
BandwidthSharingCM and CMTSData Transmission Schemes: DOCSIS
Topics discussed in this section:Topics discussed in this section:
9.33
Competing to provide high speed data transfer. Downstream: 30Mbps (5 bits/HZ x6MHz) Upstream: 12Mbps (2bits/Hz x 6Mhz)
Shared Media: Timesharing : One channel per group of subscriber ( for downstream, use of multicasting)
Top Related