1. DATA COMMUNICATION
Lecture-29

2. Recap of Lecture 28 Transmission Impairments
Performance of Transmission Medium
Wavelength
Shannon Capacity
Media Comparison

3. Overview of Lecture 29 Multiplexing Frequency division multiplexing
Wave division multiplexing
Time division multiplexing

4. Multiplexing
Set of techniques that allows the simultaneous transmission of multiple signals across a single data link

5. Multiplexing

6. Categories of Multiplexing

7. Frequency Division Multiplexing
Signals modulate different carrier frequencies
Channel - Bandwidth range to accommodate a modulated signal

8. Frequency Division Multiplexing

9. FDM Multiplexing Time Domain

10. FDM Multiplexing Frequency Domain

11. FDM Demultiplexing Time Domain

12. FDM Demultiplexing Frequency Domain

13. Wave Division Multiplexing
Conceptually the same as FDM
Light signals transmitted through fiber optic channels
Combining different signals of different frequencies (wavelengths)

14. Wave Division Multiplexing

15. Prisms in WDM
Combining and splitting of light sources are easily handled by a Prism
Prism bends a light beam based on the incidence angle and the frequency

16. Prisms in WDM

17. Time Division Multiplexing
Portions of signals occupy the link sequentially
Synchronous TDM and asynchronous TDM

18. Time Division Multiplexing

19. Synchronous TDM
Multiplexer allocates exactly the same time slot to each device at all times
Time slots are grouped into frames
For n input lines, each frame has at least n slots
It is possible to accommodate varying data rates

20. Synchronous TDM

21. Interleaving
Interleaving can be done by bit, by byte, or by any other data unit
The interleaved unit is of the same size in a given system

22. Interleaving

23. Demultiplexing Process
Demultiplexer decomposes each frame by extracting each data unit in turn
Weakness of synchronous TDM
Waste of empty slots

24. Demultiplexing Process

25. Framing Bits Various factors can cause timing inconsistencies
One or more synchronization bits (framing bits) are usually added to the beginning of each frame

26. Framing Bits

27. Synchronous TDM Example

28. Summary Multiplexing Frequency division multiplexing
Wave division multiplexing
Time division multiplexing

29. Suggested Reading Section 8.1,8.2,8.3,8.4
“Data Communications and Networking” 2nd Edition by Behrouz A. Forouzan