Chaiporn Jaikaeo Department of Computer Engineering Kasetsart University 01204325 Data Communications and Computer Networks Based on lecture materials from Data Communications and Networking 5 ID: 1030559
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1. Internet Access TechnologiesChaiporn JaikaeoDepartment of Computer EngineeringKasetsart University01204325 Data Communications and Computer NetworksBased on lecture materials from Data Communications and Networking, 5th ed.,Behrouz A. Forouzan, McGraw Hill, 2012.Revised 2018-10-04
2. OutlineTelephone linesDial-up modemsDigital Subscriber Line (DSL)Cable TV networks
3. Access TechnologyInternet access technology A data communications system that connects an Internet subscriber to an ISP (Internet Service Provider)Such as a telephone company
4. Narrowband vs. BroadbandBoth refer to access technologiesNarrowband typically 128 kbpsBroadband typically 1 MbpsNarrowband access technologiesDial-up telephone lineLeased lineBroadband access technologiesDigital Subscriber Line (DSL)Cable modemWireless/Mobile broadband: Satellite, 3G/4G, WiMAXNotes: no exact speed boundary
5. Local LoopLocal loop describes the physical connection between a telephone company Central Office (CO) and a subscriberConsists of twisted pair and dialup call with 4 KHz of bandwidthDownstreamUpstream
6. Telephone LinesTraditional telephone lines can carry frequencies between 300 and 3300 HzAll this range is used for transmitting voiceA great deal of interference and distortion can be accepted without loss of intelligibility
7. Dial-Up ModemsModemstands for Modulator/Demodulator.
8. T Lines and Analog Signals
9. PCM: Quantization12345670Input246OutputConverts continuous values of data to a finite number of discrete values
10. Quantization ErrorAssume sine-wave input and uniform quantizationnb is the number of bits per sampleKnown as the 6 dB/bit approximationSee also: http://en.wikipedia.org/wiki/Quantization_error#Quantization_noise_model
11. 56K ModemsSupport 56 kbps downlinkUplink is limited to ~33.6 kbps due to quantization noise
12. Digital Subscriber Line (DSL)Provides higher-speed access to the InternetSupports high-speed digital communication over the existing local loopsThe existing local loops can handle bandwidths up to 1.1 MHz.
13. ADSLADSL – Asymmetric Digital Subscriber LineDownstream bit rate > upstream bit rateDesigned for residential usersUnsuitable for businessesADSL operates on existing local loopsLocal loops can handle up to 1.1 MHz of bandwidthThe distance limit is ~18,000 feetThe system uses a data rate based on the condition of the local loop line
14. Bandwidth Division in ADSL
15. Discrete Multi-Tone ModulationOr DMT, based on OFDM (Orthogonal Frequency-Division Multiplexing) technique
16. Allocation and modulation of each channel are determined adaptively4 kHzBandwidth Division
17. Voice – Channel 0Idle – Channels 1-5Upstream – Channels 6-3024 data channels, 1 control channel1.44 Mbps (max) upstream bit rateActual bit rate: 64 Kbps to 1 MbpsDownstream – Channels 31-255224 data channels, 1 control channel13.4 Mbps (max) downstream bit rateActual bit rate: 500 Kbps to 8 MbpsBandwidth Division
18. ADSL Customer Residence
19. DSL Access MultiplexerOr DSLAM
20. Other DSL TechnologiesHDSL – High-bit-rate DSLVDSL – Very-high-bit-rate DSLSDSL – Symmetric DSLADSL2ADSL2+See alsohttp://en.wikipedia.org/wiki/Digital_subscriber_lineSource: AWARE. ADSL2 and ADSL2+ The new ADSL standard.
21. Cable TV NetworksStarted as a video service provider, then moved to the business of Internet accessCommunication is simplex
22. Hybrid Fiber-Coaxial NetworkOr HFCBidirectional communication is achieved
23. Data Transfer over CATVStandard: DOCSIS (Data Over Cable Service Interface Specification)Division of coaxial cable band by Cable TVTheoretical downstream data rate up to 10 GbpsTheoretical upstream data rate up to 1-2 Gbps
24. Cable Modem
25. Cable Modem Transmission SystemOr CMTS
26. Fiber To The x (FTTX)Optical broadband network architecturesFiber-to-the-nodeSource: WikipediaFiber-to-the-curbFiber-to-the-buildingFiber-to-the-home