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Chapter 2

Chapter 2. Part 2: Networking Infrastructure Networking Fundamentals. Learning Objectives. Differentiate between Analog and Digital Signals Understand Modulation and Multiplexing Identify Different Communication Media Describe digital transmission services

aristotle-delgado
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Chapter 2

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  1. Chapter 2 Part 2: Networking Infrastructure Networking Fundamentals Chapter 2

  2. Learning Objectives • Differentiate between Analog and Digital Signals • Understand Modulation and Multiplexing • Identify Different Communication Media • Describe digital transmission services • Understand packet switching networks • Appreciate different types of wireless telephony • Explain basics of local area networks Chapter 2

  3. Overview • Digital and Analog • Modulation AM and FM • Multiplexing FDM and TDM • Data Compression • Communication Media • Telephone networks Chapter 2

  4. Overview.. Continued • Digital Transmission Services • Packet Switching Networks • Wireless Telephony • Modems • Local Area Networks Chapter 2

  5. Analog and Digital Chapter 2

  6. Digital and Analog • Digital technologies are a fundamental building block of the platform that makes E-Business possible. Computers are digital. Most transmission systems are becoming digital. • Digital: Discrete • Analog: Continuously changing • Advantages of Digital: • Easier to recover signals after distortion. • Digital signals can be converted to numbers • Existing technologies are largely digital Chapter 2

  7. Digital: Signal Regeneration Chapter 2

  8. Analog to Digital Conversion • Signals in nature, sound and light, are analog • Technology is increasingly digital • Need to change analog to digital.. Music CDs, Digital telephony, digital cellular phone • Analog wave described as a set of discrete points Chapter 2

  9. Digital Signals: Pulse Code Modulation Chapter 2

  10. Pulse Code Modulation PCM • Used in digital telephone transmission • Music CD-ROMs • DVDs for movies and music • Sound Cards in PCs. Multimedia applications • In telephony: sampling done 8000 times per second, each time 8 bits are transmitted. That is, 64Kilobits/second to represent voice Chapter 2

  11. Modulation: AM and FM • Most transmission media accept only continuous signals • Information from computers in 1s and 0s • Need to use continuous signals to transmit digital values • Use a wave’s amplitude, frequency and phase and modulate them • Used in Modem (modulator + demodulator) Chapter 2

  12. Modulation: A smooth wave Chapter 2

  13. Amplitude Modulation Change amplitude, keep frequency constant Chapter 2

  14. Frequency Modulation Change frequency, keep amplitude constant Chapter 2

  15. Multiplexing • To send multiple signals over the same media simultaneously. • Enhance media capacity • FDM: Frequency division multiplexing • TDM: Time division multiplexing • Digital cellular phones use TDM and FDM to transfer signals • Digital telephone systems use multiplexing Chapter 2

  16. Frequency Division Multiplexing Multiple channels on different frequencies Chapter 2

  17. Time Division Multiplexing Splitting time into different channels Chapter 2

  18. Transmission Media • Through which signals flow • Four characteristics • Cost • Transmission capacity • Length of media before regeneration • Protection against interference Chapter 2

  19. Media Copper wire • Twisted pair copper wiring • Used in telephone lines connecting our homes low capacity 3kilobits/second • Used in local area networks. Cat 5 cables up to 100 million bits/second • Low cost, low capacity, frequent regeneration and subject to interference Chapter 2

  20. Media Copper wire Chapter 2

  21. Media Coaxial Cable • Coaxial Cable • Used in local area networks and in cable television transmission • Used for high speed Internet connection provided by cable t.v. companies • Medium cost, 100 million bits pers second, moderate protection against second Chapter 2

  22. Media Coaxial Chapter 2

  23. Media Fiber Optic • Fiber Optic Laser lights on and off and in different colors • High as 10 gigabits per second • Immune to electrical interference • High cost Chapter 2

  24. Media Fiber Optic Chapter 2

  25. Media Wireless • Two configurations • Directional • direct broadcast satellite, Microwave transmission: Satellite and terrestrial • Omni-directional • AM,FM TV broadcast, Cellular phone Chapter 2

  26. Media Satellite • Geo-synchronous orbit • Low earth orbit within 1000 miles from Earth. Few hundred satellites to cover the planet. Iridium, Teledisc, Globalstar • Medium Earth orbit within 6000 miles from Earth. More than 10 satellites to cover the planet Chapter 2

  27. Media Satellites (GEO) Chapter 2

  28. Satellite Point-to-Point Chapter 2

  29. Satellite VSAT Very small aperture terminal is popular for business applications Chapter 2

  30. Telephone Network Chapter 2

  31. Telephone Network • A hierarchical network system • Connection from home to Central office CO: Level 5 switch. Usually with low capacity copper wires • Level 4 switch (toll office) Calls that are billed pass through a toll office. Lines from here on are high capacity fiber optics • Level 3 switch (primary center) • Level 2 switch (sectional center) • Level 1 switch (regional center) Chapter 2

  32. Networks: Switched and Packet • Telephone network is switched specific connection between two ends maintained throughout the conversation. Uses PCM to translate analog signals to digital. Uses TDM and FDM to multiplex signals over trunk lines • Packet Switching Signals travel as independent packets as in US mail. Different packets (like cars) share the same line. No specific connection maintained between 2 ends. Basis of Internet and World Wide Web system Chapter 2

  33. Telephone: Digital Transmission • T-1 Carrier system • SONET/ OC (Synchronous optical network/ optical carrier system) • ISDN (Integrated services digital network) Chapter 2

  34. Digital Transmission: T series • Developed to send digital signals over old copper wires. • A hierarchy of signals • T-1 is 1.544 mbps. Connect offices to Central Offices with high capacity lines • T-3 lines carry 28 T-1 lines 44.726 mbps Chapter 2

  35. Digital Transmission T-1 Chapter 2

  36. SONET System • Optical carrier levels For fiber optic transmission • OC-1 52 mbps • OC-3 155 mbps • OC-9 466 mbps • OC-192 10,00 mbps Chapter 2

  37. Wireless Technologies • Wide area communication Uses media from a telephone company Cellular systems, Satellite systems, Pagers • Local area communication Network within ones property Wireless LANs • Personal area network Less than 10 meter Chapter 2

  38. Wireless Wide Area • Analog cellular system advanced mobile phone system Cells, Mobile telephone switching office (MTSO), Public switched telephone network (PSTN) Chapter 2

  39. Wireless Wide Area • Digital Cellular System Modulation is used to transmit voice as a digital signal. TDM is used to multiplex several conversation over a single channel. Permits more lines than AMPS • Personal Communication Service Similar to digital cellular system. Uses different frequency spectrum Chapter 2

  40. Wireless Wide Area • Nextel One transmitter covering a large area. 2-way dispatch service. Used by Taxis and public safety people • Paging One directional, point-to-point, character/ numerical based • I-Mode. Packet based. Offered by NTT DoCoMo in Japan. Sound, color and video over hand held devices Chapter 2

  41. Wireless Personal Area Network • Bluetooth • Connect home and office based systems in a network • Connect PCs, printers, telephones, stereos, TVs • Packet switching technology Chapter 2

  42. Modems • Modems allow signals from a PC to travel from home to the telephone company’s central office or the cable company • PC Modem using telephone line • Cable Modem using coaxial cable connection from cable company • DSL Modem uses digital subscriber line Chapter 2

  43. Modems PC modem Chapter 2

  44. Modems Cable Modems Chapter 2

  45. Modems DSL Chapter 2

  46. Local Area Network • Owned by a single organization and physically within their premises. • Ethernet is the most popular architecture • Uses coaxial cable and cat 5 twisted copper wire • Capacity of 10 million bits/second and “High speed” Ethernet is 100 million bits/second Chapter 2

  47. Local Area Network: Ethernet Chapter 2

  48. LAN Wireless • Radio frequency to transmit • Little installation • Supports mobility • Standard is IEEE 802.11b: 11 megabits per second capacity • Emerging standard IEEE 802.11a: 54 megabits per second capacity • Two popular configurations • Peer-to-peer and client/server Chapter 2

  49. LAN Wireless Peer to peer wireless local area network communicating through a antenna system Chapter 2

  50. LAN Wireless Wireless laptops connecting to a terrestrial LAN through a network access point that can support 50 clients over 500 feet Chapter 2

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