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Understanding Networking: From Analog Signals to Digital Communication

This session explores the transition from analog to digital technologies, detailing how sensory inputs like sound and temperature are represented as continuous signals in the analog realm. It explains the process of converting these signals into digital format via Pulse Code Modulation (PCM), including the steps of sampling, quantization, and encoding. The significance of telecommunications and various types of networks is also discussed, alongside comprehensive insights into local area networks (LANs), their functions, and the benefits they offer for efficient data communication.

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Understanding Networking: From Analog Signals to Digital Communication

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Presentation Transcript

  1. LBSC 690 Session 3 Networking

  2. Analog to Digital • We live in an analog world: • Sound, temperature, light, etc. • Sensory inputs. • Are continuous signals. • Can assume all (essentially infinite) values in a given interval. • Basis for analog computers: • Uses electrical voltage/current to variables. to represent.

  3. Digital • Discrete representation: assumes a finite number of values in a given interval. • Basis for digital computers: • Use 2 discrete values to represent data, & instructions. (Binary system). • Analog signals converted to digital by Pulse Code Modulation (PCM).

  4. PCM • Three step process: • Analog signal is sampled: • Nyquist’s Theorem. • Samples are quantized. • Quantized samples are encoded into binary digits, called “bits” for short. • See handout.

  5. Evolution • Computers initially stand alone. • Need to communicate. • Transmit data at a distance. • Communications: • Data communication. • Telecommunication: • Provides electrical communications at a distance. • Service provided by a number of companies internationally. • The “telecommunications industry.”

  6. Telecommunications Industry • Carriers: • LECs (RBOCs: 7 to 4); CLECs. • IXCs. • Internet Service Providers (ISPs). • Vendors/Consultants & Manufacturers. • Judicial/Political/Legislative: • Regulatory agencies. • Standards Making Organizations. • Customers: business & residential. • Technology and research.

  7. Networking • Simplest form: • Directly connect two communicating devices. • Not practical solution. • Problem of topology: • How to deal with fully connected mesh. • Need network. • Nodes and segments.

  8. The Universal Seven Part Data Model DTE DTE DCE DCE DTE/DCE Interface DCE/DTE Interface Transmission Channel DTE: Data Terminal Equipment DCE: Data Communication Equipment

  9. Network (Cont’d.) S N NETWORK “Local loop” N S N S S: Network Station N N: Network Node S

  10. Network Types • Switched Communication Network: • Circuit-switched. • Packet–-switched. • Broadcast communication Network: • Packet radio network. • Satellite network. • Local area network.

  11. Generic Switching Network • Reference handout.

  12. Concepts: • Bandwidth • Measure of channel capacity: frequency range • Radio Spectrum (Next Slide) • Frequencies available for telecommunications • Modulation • Process of embedding intelligence in a carrier wave • Multiplexing • Process that combines multiple calls or messages on a single channel • Examples; TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access)

  13. Spectrum • A limited resource • Government controlled: FCC & ITU, e.g. • Some assigned frequencies: • Am radio: 535-1635 KHz • Analog cordless phones: 44-49 MHz • TV channels 2-6: 54-88 MHz • FM radio: 88-108 MHz • TV channels 7-13: 174-216 MHz • Cellular phones: 806-890 MHz • PCS: 900-929 MHz • Satellite TV (small dish): 11.7-12.7 GHz

  14. Cell Phones • More than 115 million users in US • 46,000 people subscribing every day • Based on concept of cells • 10 sq. mi. in area with a Base Station in it • Low power: 0.3 & 6 watts • Mobile Telephone Switching Office (MTSO). • Special codes: electronic serial no. (ESN), mobile identif. no.(MIN, system ident, code (SID). • Analog vs. digital. • American vs. European approaches • GSM (Global System For Mobile communication) • TDMA vs. CDMA

  15. LANs • What are they? • Need & functions. • Hardware/software components. • Concept of packets. • Ethernet and token ring. • ANSI/ IEEE 802.3 (ISO 8802-3) • Need to interconnect LANs.

  16. LANs • Data communication facilities designed to provide high-speed switched connections between processors peripherals and terminals within a local area, e.g., buildings or a campus.

  17. File sharing Printer sharing CD ROM sharing On-line databases Groupware OPAC access Dial in & out Fax in & out Voice-video-multi-media E-mail Internet access LAN Functions

  18. LAN Benefits • Shared access • Increased security • Application and data highway • Adding new applications is done once (on server) • Support services more effective and lower cost

  19. LAN Installation • Network Operating System (NOS). • Network Interface Cards (NIC). • Cabling and connectors. • Hubs/ Switches. • Network Servers: • File, Print, Communication, etc. • Clients

  20. TRAINING • Network Management: • Network Administrator & Support Personnel. • Certification. • Continuing education. • User training.

  21. Ethernet • Developed in 1973 at Xerox Corporation’s Palo Alto Research Center (PARC). • Developed by Bob Metcalfe. • Uses the Ethernet Protocol. • Protocol: A code prescribing strict adherence to correct etiquette and precedence. • Communication protocols: symbols (Character set), rules for sequence and timing of messages, and procedures for error detection and handling. • Messages broken into frames (packets). • With source and destination addresses.

  22. Ethernet • Broadcast network • Carrier Sense Multiple Access/Collision Detection (CSMA/CD) • Collision retry (random wait) • Need for repeaters • Hubs • Basic, Smart, Intelligent, Switches • Bridges • Routers (internetting)

  23. Network Topology • Bus • Star • Ring • Mesh • Hybrid

  24. Transmission Channels (Media) • 4-wire phone 3Kbps 200 ft. • UTP 100Mbps 100 ft. • STP 16Mbps 100 ft. • Coax 10Mbps 500 ft. • Fiber optic 10Gbps 2-5 km.

  25. The Internet • Historical development. • TCP/IP Protocol Suite. • Telnet. • FTP. • E-mail. • Assignment 1: • Two exercises. • Packet switching. • Addressing: URLs.

  26. Packet Switched Networks • General Switching Diagram: • Reference Handout

  27. Modems • Function: • Modulation – demodulation. • Types and speeds: • Standard • ISDN. • Cable TV. • xDSL. • Satellite

  28. World Wide Web (WWW) • Historical development. • HTTP. • HTML. • XML. • Multimedia.

  29. Trends • Convergence. • Voice over IP (VIP). • Wireless. • 3G (Third Generation) • PCS (Personal Communication Services) • Ubiquitous networking • Remote device control.

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