- Fact:
- The capacity (data rate) of
a transmission medium is
very large
Example:
- One optical fiber wire
can transmit
≥ 1 TeraBits/sec !!!
(See: click here)
- One optical fiber wire
can transmit
≥ 1 TeraBits/sec !!!
- A single user can not fully use 1 TeraBits/sec data rate...
- The capacity (data rate) of
a transmission medium is
very large
- Common practice:
- Multiple users usually share one single communication channel
- Multiplexing:
- multiplexing = the techniques used to share a communication medium
- There are
2 commonly used
multiplexing techniques
used to
share transmission capacity
in the
physical layer
(= signal transmission layer):
- The transmission channel can be
shared
in the time dimension:
- Time division multiplexing
- The transmission channel can be
shared
in the "space" (frequencies)
dimension:
- Frequency division multiplexing
Note:
- The "space" is
a communication medium is the
range of frequencies inside
bandwidth of the
transmission medium:
- The transmission channel can be
shared
in the time dimension:
- Analogy:
- Sharing a
house with
4 rooms
among 4 persons:
- Time sharing:
- Each person gets to use the entire house for 25% of the time
- Space sharing:
- Each persn gets to use one room all the time
- Time sharing:
- Sharing a
house with
4 rooms
among 4 persons: