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CHAPTER Multiplexing

CHAPTER Multiplexing. Chapter Objectives. Describe direct and inverse multiplexing List and explain the different types of multiplexing techniques used in electronic and optical transmission Give illustrative examples of the use of multiplexers in the field. Chapter Modules.

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CHAPTER Multiplexing

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  1. CHAPTER Multiplexing

  2. Chapter Objectives • Describe direct and inverse multiplexing • List and explain the different types of multiplexing techniques used in electronic and optical transmission • Give illustrative examples of the use of multiplexers in the field

  3. Chapter Modules • Direct and inverse multiplexing • Listing of multiplexing techniques and Frequency Division Multiplexing • Time Division and Wave Division Multiplexing • Practical multiplexer connections

  4. MODULE 1 Direct and Inverse Multiplexing

  5. Overview Of Direct Multiplexing • Direct multiplexing or multiplexing is the same as channel splitting • It means the splitting of one physical line into multiple communication channels • A communication channel is one that engages in a communication session • The usage of the term multiplexing in general means direct multiplexing

  6. Direct Multiplexing Example Session 1 Session 1 Session 2 Mux Mux Session 2 Session 3 Session 3 One physical line carrying multiple channels. A B

  7. Sample Application Areas • Mainframe-based communication • Long-distance links • Fiber-optic communication • A relatively new introduction • Digital lines such as DSL

  8. Overview Of Inverse Multiplexing • Combination of multiple transmission lines or multiple communication channels to support a single communication session • Binding of multiple transmission lines for the purpose of engaging in a single communication session

  9. Inverse Multiplexing One communication channel Session 1 Session 1 Inv.. Mux Inv.. Mux Multiple Transmission Lines A B

  10. Bonding • Inverse multiplexing is also known as bonding when it is done dynamically • For example, this can be achieved in modem and ISDN transmission • Bonding is normally carried out dynamically

  11. Sample application Areas • Video conferencing • Conducted over ISDN lines • T-1 line inverse multiplexing • ATM inverse multiplexing

  12. Inverse Multiplexing with Analog Lines • The primary purpose is to increase the speed of Internet connection made over regular analog telephone lines • Modems are being introduced to combine analog telephone lines • Combination of two lines operating at 56K bps each results in an effective communication speed of 112K bps

  13. In Summary • Direct multiplexing • Maximize the economical use of cables • Inverse multiplexing • Increase the communication speed of a single communication session

  14. END OF MODULE

  15. MODULE 2 Communication Lines, Channels and Sessions

  16. Lines, Channels and Sessions • A transmission line is a physical medium that carries the information • Coaxial cable • A communication channel is a conduit for the flow of information • Multiple channels in physical medium • A communication session is the actual process of engaging in a communication task

  17. One Transmission Line and Multiple Communication Channels Line Channels Mainframe Coaxial cable Terminals

  18. Multiple Transmission Lines and One Communication Session 2 B Channels each operating at 64K bps Micro Single Session Multiple ISDN lines (multiple B channels). Combined speed = 6 X 64 = 384K bps

  19. One Transmission Line, One Channel and Multiple Sessions Internet Micro Data Packets Internet client engaged in multiple communication sessions.

  20. END OF MODULE

  21. MODULE 3 Frequency Division Multiplexing (FDM)

  22. Multiplexing Techniques • Frequency Division Multiplexing • Time Division Multiplexing • Statistical Time Division Multiplexing • Wave Division Multiplexing

  23. Direct Multiplexing Techniques • Frequency Division Multiplexing • Channel division is based on frequency • Time Division Multiplexing • Time slots are assigned for each channel • Statistical Time Division Multiplexing • A variation of Time Division Multiplexing concept that optimizes on the concept of Time Division multiplexing • Wave Division Multiplexing, the multiplexing is based on different wavelengths of light

  24. Frequency Division Multiplexing (FDM) Analog F1 F1 MUX MUX F2 F2 F3 F3 Each channel is assigned A different frequency (Half-duplex Example) A B

  25. Computer Communication Using FDM Digital Analog Analog Modem MUX Micro One or Modems May Be Incorporated Within the Multiplexer As Well.

  26. END OF MODULE

  27. MODULE 4 Time Division and Wave Division Multiplexing

  28. Time Division Multiplexing in a Nutshell • Time division simply allows a fixed period of time for communication for each channel

  29. Time Division Multiplexing (TDM) Digital Analog T1 MUX Modem T2 T3 T1 T2 T3 T1 T2 T3 Time slots are equally divided among channels.

  30. Salient Features of Time Division Multiplexing • Each channel is assigned a fixed period of time for transmission • The opportunity to transmit is given on a round-robin basis • Time division multiplexers can therefore processes the information in digital form • A modem is only required to connect a multiplexer to an analog line

  31. Drawback with Time Division Multiplexing • TDM assigns a fixed period of time for each channel • When a channel does not have any information to transmit during the allocated time period, it still remains connected • Either part or the entire portion of the allocated time period is wasted

  32. Statistical Time Division Multiplexing Digital Analog T1 MUX Modem T2 T3 T1 T2 T3 T2 T3 Time slots are not equally divided among channels.

  33. Statistical Time Division Multiplexing Properties • STDM is similar to TDM except for one difference • A time slice may be shortened due to the absence of data for transmission • Each channel is initially assigned a fixed period of time • The time period is forfeited in part or in full if there is no data to be transmitted • Obviously, STDM is more efficient than TDM

  34. END OF MODULE

  35. MODULE 5 Wave Division Multiplexing

  36. Wave Division Multiplexing (WDM) • Similar to FDM • Light waves are involved in place of electronic signals • The term wave length is used instead of the term frequency • Note that the wave length is inversely proportional to frequency • Used in fiber optics transmission

  37. Wave Division Multiplexing Connection Light rays of different wave lengths (frequencies) are assigned for different channels. W1 W1 W2 W2 W3 W3 Detect and differentiate light rays of different wave lengths at the receiving end.

  38. END OF MODULE

  39. MODULE 6 Practical Multiplexer Connections

  40. Module Objectives • Provide practical examples in the use of multiplexers • Use of multiplexers in a mainframe environment • Use of multiplexers in Wide Area Networks (WAN)

  41. Use Of Multiplexers in a Mainframe Environment MUX Modem Modem Cluster Controller MUX Terminal Terminal Terminal

  42. Wide Area Multiplexing SanFrancisco 56 kbps FEP MUX MUX Mainframe MUX Modem 56 Kbps 112 kbps

  43. Wide Area Multiplexing Cont. Los Angeles Long Beach 112 56 Mod. Mod. 56 18.6 28 18.6 18.6 28 Term. Term. Term. Term. Term.

  44. Wide Area Multiplexing Observation • Multiple channels are multiplexed and de-multiplexed • A combination of multiplexers can be used in combining faster and slower channels

  45. END OF MODULE END OF CHAPTER

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