Time division Multiplexing(TDM)

• Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.

https://en.wikipedia.org/wiki/Time-division_multiplexing

 

Time division Multiplexing TDM

• Multiplexing: a system resource is shared among multiple

users

– Analogy: CPU sharing

Mechanisms to multiplexing

– Time-division multiplexing (TDM)

– Frequency-division multiplexing (FDM)

– Statistical multiplexing

Statistical Multiplexing

The physical link is shared over time (like TDM)

• But does not have fixed pattern. This is called

statistical multiplexing

– Sequence of A & B packets are sent on demand, not

predetermined slots

https://www2.cs.duke.edu/courses/spring19/compsci356/slides/02NetArch.pdf

• Data Communications and Computer Networks

Under the simplest conditions, a medium can carry only one signal at any moment in time.

For multiple signals to share one medium, the medium must somehow be divided, giving each signal a portion of the total bandwidth.

The current techniques that can accomplish this include frequency division multiplexing, time division multiplexing, and code division multiplexing.

Frequency Division Multiplexing

Assignment of non-overlapping frequency ranges to each “user” or signal on a medium.  Thus, all signals are transmitted at the same time, each using different frequencies.

Time Division Multiplexing

Sharing of the signal is accomplished by dividing available transmission time on a medium among users.

Synchronous Time Division Multiplexing

The original time division multiplexing.

Statistical Time Division Multiplexing

A statistical multiplexor transmits only the data from active workstations

Wavelength Division Multiplexing

Wavelength division multiplexing multiplexes multiple data streams onto a single fiber optic line.

Discrete Multitone (DMT)

A multiplexing technique commonly found in digital subscriber line (DSL) systems

Code Division Multiplexing

Also known as code division multiple access

An advanced technique that allows multiple devices to transmit on the same frequencies at the same time.

http://facweb.cs.depaul.edu/cwhite/Book/Slides%20Third%20Ed/Old%20TE%20Chapter%205.ppt