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. Chapter 11 Direct and Inverse Multiplexing
4/24/2017
MODULE 1
Direct and Inverse Multiplexing
(c) Copyright N Ganesan

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
Mux
Mux
Session 2
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
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 Inverse multiplexing
Maximize the economical use of cables
Inverse multiplexing
Increase the communication speed of a single communication session

14. END OF MODULE

15. Chapter 11 Communication Lines, Channels and Sessions
4/24/2017
MODULE 2
Communication Lines, Channels and Sessions
(c) Copyright N Ganesan

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
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. Frequency Division Multiplexing (FDM)
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. Time Division and Wave Division Multiplexing
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. Wave Division Multiplexing
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. Practical Multiplexer Connections
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
Controller
Cluster
MUX
Terminal
Terminal
Terminal

42. Wide Area Multiplexing
San Francisco
56 kbps
FEP
MUX
MUX
Mainframe
MUX
56 Kbps
Modem
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