Multiplexing is a set of techniques that allows the simultaneous transmission of multiple signals across a single data link. There are two main types: frequency division multiplexing which combines signals by assigning each a different frequency, and time division multiplexing which divides the link into sequential time slots and allocates slots to different signals in turn. Time division multiplexing can be synchronous, allocating fixed time slots, or asynchronous with variable slot allocation.

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

2. Multiplexing

3. Frequency Division
Multiplexing

4. FDM Multiplexing
Time Domain

5. FDM Multiplexing
Frequency Domain

6. FDM Demultiplexing
Time Domain

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

8. Time Division Multiplexing

9. 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

10. Synchronous TDM

11. 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

12. Interleaving

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

14. Demultiplexing Process