Upload
alicia-kay-morris
View
227
Download
0
Embed Size (px)
Citation preview
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
1/29
Data Communications SystemsCh 9: Using Telephone and Cable
Networks for Data Transmission
JinKyu Lee, [email protected]
Include the course code (MSIS4523) in every email subject!!
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
2/29
Topics
Telephone NetworksConcepts
Local loop, Trunks, Switching office, LEC, IXC, LATA, PoP
SignalingBandwidth Utilization
Dial-up ModemDigital Subscriber Line (DSL)
Cable TV NetworksHybrid Fiber-Coaxial (HFC) Network
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
3/29
3
TELEPHONE NETWORK
Telephone networks use circuit switching. The telephone network had its beginnings in the late1800s. The entire network, which is referred to as
the Plain Old Telephone System (POTS), was originally an analog system using analog signals to transmit voice.
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
4/29
4
Major Components
Local loop: Twisted pair that connects thesubscriber to the end officeFirst three digits of the phone numberidentify that office; next four digitsidentify the local loop number
Trunks: Transmission media betweenoffices (fiber, satellite)
Switching office: Houses the switches likethose introduced in Chapter 8
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
5/29
5
A telephone system
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
6/29
6
Switching offices in a LATA
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
7/297
Major Concepts (US Market)
Local Access Transport Area (LATA)One or more Local Exchange Carriers (LECs) provideservices in each LATAIncumbent LEC: the original LEC that started toprovide service in a LATA (used to hold a monopolyuntil 1996)Competitive LEC: new carriers.
Inter-eXchange Carriers (IXCs) (long distancecompanies) provide connection between LATAs
Any IXC that want to provide services inside a LATAmust have a Point of Presence (POP) in the LATAThe local exchange carrier must provide everysubscriber with all POPs inside the LATA
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
8/29
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
9/299
Signaling
Modern phone systems have in-bandsignalingOne network transfers data, another sets up the calland provide control information to the endpointsTwo networks may use separate channels, but theyare part of the same physical link
The protocol for signaling is SignalingSystem Seven (SS7)
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
10/29
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
11/29
11
DIAL-UP MODEMS
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,where a great deal of interference and distortion can
be accepted without loss of intelligibility.
Covered in Chapter 6 Bandwidth Utilization
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
12/29
12
Modulation/demodulation
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
13/29
13
Uploading and downloading in 56K modems
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
14/29
14
DIGITAL SUBSCRIBER LINE
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.
Covered in Chapter 6 Bandwidth Utilization
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
15/29
15
DSL
Local loop twisted pair can handle up to 1.1MHz, but voice only requires 4kHzPhone companies were filtering the higherfrequencies, by removing the filters they hadaccess to more frequenciesAsymmetric DSL was one of the firsttechnologies in this set
Use Discrete Multi-tone (DMT) Technique for modulationCombination of QAM (within channel) and FDM (for the 256channels)
Bandwidth of 1.104 MHz divided into 256 channelsAdaptive; tests the conditions and bandwidth availability of thelocal loop before settling on a data rate
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
16/29
16
Bandwidth division in ADSL
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
17/29
17
Discrete multitone technique
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
18/29
18
ADSL modem
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
19/29
19
DSLAM
Telephone company uses a DSL access multiplexerto multiplex the data, packetize it, and send it to the ISPs
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
20/29
20
Other Forms of DSL
ADSL Lite: Splitting between low pass and high pass isdone at the telephone companyplugs into your standard phone jackHigh-bit-rate DSL (HDSL) uses two twisted pair toachieve full duplex transmissionSymmetric DSL: Achieves a higher bit rate like HDSL,but only uses one pairVery-high-bit-rate (VDSL): Can use fiber, coax, or TP toachieve high bit rates
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
21/29
21
Summary of DSL technologies
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
22/29
22
CABLE TV NETWORKS
The cable TV network started as a video service provider, but it has moved to the business of Internet access. Cable companies are now competing with telephone companies for the residential customer
who wants high-speed data transfer. we discuss how this network can be used to provide high-speed access to the Internet.
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
23/29
23
Traditional cable TV network
Unidirectional
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
24/29
24
Hybrid fiber-coaxial (HFC) network
Bi-Directional
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
25/29
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
26/29
26
Division of coaxial cable band by CATV
Downstream data are modulated using the 64-QAMmodulation technique. The theoretical downstream
data capacity is 30 Mbps. Upstream data aremodulated using the QPSK modulation technique.
The theoretical upstream data rate is 12 Mbps.
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
27/29
27
How they do it
Users need a cable modemmore of afilter than a modem to split the signalsbetween video and voiceThe cable companies install a cablemodem transmission system (CMTS) inthe distribution hubs
Receives data from the Internet and passes itto the combiner
Combines it with video signals for transmission
Pushed to subscriberReceives data from subscriber and passes itto the Internet
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
28/29
28
Cable modem (CM)
8/3/2019 MSIS 4523 Ch9.Using Telephone and Cable NWs
29/29
Cable modem transmission system (CMTS)