February 14, 2020
Amitraj
Multiplexing
Multiplexing is a technique used to combine and send the multiple data streams over a single medium. The process of combining the data streams is known as multiplexing and hardware used for multiplexing is known as a multiplexer.
Multiplexing is achieved by using a device called Multiplexer (MUX) that combines n input lines to generate a single output line. Multiplexing follows many-to-one, i.e., n input lines and one output line.
Demultiplexing is achieved by using a device called Demultiplexer (DEMUX) available at the receiving end. DEMUX separates a signal into its component signals (one input and n outputs). Therefore, we can say that demultiplexing follows the one-to-many approach.
Time Division Multiplexing
1. It is the digital multiplexing technique.
2. Channel/Link is not divided on the basis of frequency but on the basis of time.
3. Total time available in the channel is divided between several users.
4. Each user is allotted a particular time interval called time slot or slice.
5. In TDM the data rate capacity of the transmission medium should be greater than the data rate required by sending of receiving devices.
6. In Time Division Multiplexing technique, all signals operate at the same frequency with different time.
7. In Time Division Multiplexing technique, data is not transmitted simultaneously rather the data is transmitted one-by-one.
8. In TDM, the signal is transmitted in the form of frames. Frames contain a cycle of time slots in which each frame contains one or more slots dedicated to each user.
9. It can be used to multiplex both digital and analog signals but mainly used to multiplex digital signals.
There are two types of TDM:
1. Synchronous TDM
2. Asynchronous TDM
Synchronous TDM
1. A Synchronous TDM is a technique in which time slot is preassigned to every device.
2. In Synchronous TDM, each device is given some time slot irrespective of the fact that the device contains the data or not.
3. If the device does not have any data, then the slot will remain empty.
4. In Synchronous TDM, signals are sent in the form of frames. Time slots are organized in the form of frames. If a device does not have data for a particular time slot, then the empty slot will be transmitted.
5. The most popular Synchronous TDM are T-1 multiplexing, ISDN multiplexing, and SONET multiplexing.
6. If there are n devices, then there are n slots.
Concept of Synchronous TDM
In the above figure, the Synchronous TDM technique is implemented. Each device is allocated with some time slot. The time slots are transmitted irrespective of whether the sender has data to send or not.
Asynchronous TDM
1. An asynchronous TDM is also known as Statistical TDM.
2. An asynchronous TDM is a technique in which time slots are not fixed as in the case of Synchronous TDM. Time slots are allocated to only those devices which have the data to send. Therefore, we can say that Asynchronous Time Division multiplexor transmits only the data from active workstations.
3. An asynchronous TDM technique dynamically allocates the time slots to the devices.
4. In Asynchronous TDM, total speed of the input lines can be greater than the capacity of the channel.
5. Asynchronous Time Division multiplexor accepts the incoming data streams and creates a frame that contains only data with no empty slots.
6. In Asynchronous TDM, each slot contains an address part that identifies the source of the data.
Concept of Asynchronous TDM
Multiplexing is a technique used to combine and send the multiple data streams over a single medium. The process of combining the data streams is known as multiplexing and hardware used for multiplexing is known as a multiplexer.
Multiplexing is achieved by using a device called Multiplexer (MUX) that combines n input lines to generate a single output line. Multiplexing follows many-to-one, i.e., n input lines and one output line.
Demultiplexing is achieved by using a device called Demultiplexer (DEMUX) available at the receiving end. DEMUX separates a signal into its component signals (one input and n outputs). Therefore, we can say that demultiplexing follows the one-to-many approach.
Time Division Multiplexing
1. It is the digital multiplexing technique.
2. Channel/Link is not divided on the basis of frequency but on the basis of time.
3. Total time available in the channel is divided between several users.
4. Each user is allotted a particular time interval called time slot or slice.
5. In TDM the data rate capacity of the transmission medium should be greater than the data rate required by sending of receiving devices.
6. In Time Division Multiplexing technique, all signals operate at the same frequency with different time.
7. In Time Division Multiplexing technique, data is not transmitted simultaneously rather the data is transmitted one-by-one.
8. In TDM, the signal is transmitted in the form of frames. Frames contain a cycle of time slots in which each frame contains one or more slots dedicated to each user.
9. It can be used to multiplex both digital and analog signals but mainly used to multiplex digital signals.
There are two types of TDM:
1. Synchronous TDM
2. Asynchronous TDM
Synchronous TDM
1. A Synchronous TDM is a technique in which time slot is preassigned to every device.
2. In Synchronous TDM, each device is given some time slot irrespective of the fact that the device contains the data or not.
3. If the device does not have any data, then the slot will remain empty.
4. In Synchronous TDM, signals are sent in the form of frames. Time slots are organized in the form of frames. If a device does not have data for a particular time slot, then the empty slot will be transmitted.
5. The most popular Synchronous TDM are T-1 multiplexing, ISDN multiplexing, and SONET multiplexing.
6. If there are n devices, then there are n slots.
Concept of Synchronous TDM
In the above figure, the Synchronous TDM technique is implemented. Each device is allocated with some time slot. The time slots are transmitted irrespective of whether the sender has data to send or not.
Asynchronous TDM
1. An asynchronous TDM is also known as Statistical TDM.
2. An asynchronous TDM is a technique in which time slots are not fixed as in the case of Synchronous TDM. Time slots are allocated to only those devices which have the data to send. Therefore, we can say that Asynchronous Time Division multiplexor transmits only the data from active workstations.
3. An asynchronous TDM technique dynamically allocates the time slots to the devices.
4. In Asynchronous TDM, total speed of the input lines can be greater than the capacity of the channel.
5. Asynchronous Time Division multiplexor accepts the incoming data streams and creates a frame that contains only data with no empty slots.
6. In Asynchronous TDM, each slot contains an address part that identifies the source of the data.
Concept of Asynchronous TDM
