Differentiate between Synchronous TDM and Asynchronous TDM in Computer Network

Synchronous TDM

Synchronous TDM is primarily known as synchronous because each time slot is preauthorized to a continuing source. Synchronous TDM is a data transfer approach during which there may be a continuous flow of data signals followed by timing signals. It helps to support that the send and therefore the receiver are synchronized with one another.

The time slots are broadcasted regardless of whether the sources have any information to transmit or not. Thus, for the benefit of the integrity of execution, the channel space is wasted.

Asynchronous TDM

Asynchronous TDM is called statistical division multiplexing. It is a method in which time slots are not permanent as in Synchronous TDM. Time slots are assigned to only those machines which have the information to send the data.

This transmission approach transmits one character or 8 bits at a time. In this approach, before the transmission process begins, each character transfers the beginning bit. After sending the character, it also sends the end bit. With the character bits and begin and stop bits, the entire number of bits is 10 bits.

The major differences between the Synchronous Time Division Multiplexing (STDM) and Asynchronous Time Division Multiplexing (ATDM) are as follows −

In synchronous TDM, the unlimited speed of the input lines is never higher than the volume of the direction.In asynchronous TDM, the total speed of the input lines can be higher than the magnitude of the direction.
Suppose that we have n input lines. The frame includes an endless number of minimum n time slots.Suppose that we have n input lines. The frame consists of n greater than m slots with m smaller than n.
Synchronous TDM supports less device than asynchronous TDM.Asynchronous TDM can provide more devices than synchronous TDM.
It provides the equivalent number of input lines as asynchronous TDM with a higher size connection.It provides an equal number of input lines as asynchronous TDM with a lower size connection.
Due to static allocation, bandwidth is wasted.Effective utilisation of the line bandwidth.
It is suitable for bit/byte interleaving.It can use a large unit of data for interleaving.
It can be less overhead for addressing.It can be a large overhead for addressing.
It accommodates traffic of fixed data costs.It can accommodate the traffic of shifting data costs by running the dimension of the time slots.
Buffering is not completed, the frame is transmitted after a specific interval of time whether someone has information to send or not.Buffering is completed and only those inputs are given slots within the output frame whose buffer includes information to send.
In Synchronous TDM, de-multiplexer at receiving end decomposes each frame, removes framing bits, and separates data units successively. This extracted data unit from the frame is then moved to the destination device.In Asynchronous TDM, de-multiplexer at receiving end decomposes each frame by testing the local address of every data unit. This extracted data unit from the frame is then moved to the destination device.
Synchronization bits are used at the start of every frame.There are no synchronization bits used.

Updated on: 05-May-2021

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