What is Multiplexing? Types, and their Applications

The term “Multiplexing” or “Muxing” is one kind of technique for combining multiple signals like analog as well as digital into one signal over a channel. This technique is applicable in telecommunications as well as computer networks. For instance, in telecommunications, one cable is used for carrying different telephone calls. In the year 1870, the multiplexing technique is invented first in telegraphy, and at present, it is extensively used in communications. The scientist “George Owen Squier” was recognized the growth of multiplexing in telephony in the year 1910. The signal which is multiplexed will be transmitted over a cable or channel and separates the channel into numerous logic channels. This article discusses what is multiplexing, Different types of multiplexing techniques, and applications. Please refer the link to know about Multiplexer and Demultiplexer – Electronics Circuits

What is a Multiplexing?

Muxing (or) multiplexing can be defined as; it is a way of transmitting various signals over a media or single line. A common kind of multiplexing merges a number of low-speed signals to send over an only high-speed link, or it is used to transmit a medium as well as its link with the number of devices. It provides both privacy & Efficiency. The entire process can be done using a device namely MUX or multiplexer, and the main function of this device is to unite n-input lines for generating a single output line. Thus MUX has many inputs & single output. A device is called DEMUX or demultiplexer is used at the receiving end which divides the signal into its component signals. So It has single input and number of outputs.


Types of Multiplexing Techniques

Multiplexing techniques are mainly used in communication, and these are classified into three types. The 3 types of multiplexing techniques include the following.

  • Frequency Division Multiplexing (FDM)
  • Wavelength Division Multiplexing (WDM)
  • Time Division Multiplexing (TDM)

1). Frequency Division Multiplexing (FDM)

The FDM is used in telephone companies in the 20th century in long-distance connections for multiplexing number of voice signals using a system like a coaxial cable. For small distances, low-cost cables were utilized for different systems such as bell systems, K-and N-carrier, however, they don’t let huge bandwidths. This is analog multiplexing used to unite analog signals. This type of multiplexing is useful when the link’s bandwidth is better than the United bandwidth of the transmitted signals.

Frequency Division Multiplexing
Frequency Division Multiplexing

In FDM, signals are produced by transmitting various device modulated carrier frequencies, and then these are united into a solo signal which can be moved by the connection. To hold the adapted signal, the carrier frequencies are divided by sufficient bandwidth, & these ranges of bandwidths are the channels through the different traveling signals. These can be divided by bandwidth which is not used. The best examples of the FDM comprise signal transmission in TV and radio.

2). Wavelength Division Multiplexing (WDM)

In fiber communications, the WDM (Wavelength Division Multiplexing) is one type of technology. This is the most useful concept in high-capacity communication systems. At the end of the transmitter section, the multiplexer is used to combine the signals as well as at the end of receiver section, de-multiplexer for dividing the signals separately. The main function of WDM at the multiplexer is for uniting various light sources into an only light source, and this light can be changed into numerous light sources at the de-multiplexer.

Wavelength Division Multiplexing
Wavelength Division Multiplexing

The main intention of WDM is to utilize the high data rate capacity of the FOC (fiber optic cable). The high data rate of this FOC cable is superior to the data rate of the metallic transmission cable. Theoretically, the WDM is similar to the FDM, apart from the data transmission through the FOC in which the multiplexing & de-multiplexing occupies optical signals. Please refer the link to know more about Wavelength Division Multiplexing (WDM) Working and Applications

3). Time Division Multiplexing (TDM)

The Time division multiplexing (or) TDM is one kind of method for transmitting a signal over a channel of particular communication with separating the time edge into slots. Like single slot is used for each message signal.

Time Division Multiplexing
 Time Division Multiplexing

TDM is mainly useful for analog and digital signals, in which several channels with low speed are multiplexed into high-speed channels used for transmission. Depending on the time, every low-speed channel will be assigned to an exact position, wherever it works in the mode of synchronized. Both the ends of MUX and DEMUX are synchronized timely & at the same time switch toward the next channel.

Types of Time Division Multiplexing

The different types of TDM include the following.

  • Synchronous TDM
  • Asynchronous TDM
  • Interleaving TDM
  • Statistical TDM
Types of TDM
 Types of TDM

1). Synchronous TDM

The synchronous TDM is very useful in both analog as well as digital signals. In this type of TDM, the connection of input is allied to a frame. For example, if there are n-connections in the frame, then a frame will be separated into n-time slots, and for every unit, each slot is assigned to every input line.

In the sampling of synchronous TDM, the speed is similar for every signal, as well as this sampling needs a clock (CLK) signal at both the ends of sender & receiver. In this type of TDM, the multiplexer assigns the similar slot for each device at every time.

2).Asynchronous TDM

In asynchronous TDM, for different signals, the rate of sampling is also different, and it doesn’t need a general clock (CLK). If the device has nothing for transmitting, then the time slot is assigned to a new device. The design of a commutator otherwise de-commutator is not easy & the bandwidth is low for this type of multiplexing, and it is applicable for not synchronous transmit form network.

3). Interleaving TDM

The TDM can be imagined like two speedy rotary switches on the multiplexing & demultiplexing surface. These switches can be rotated & synchronized in reverse directions. Once the switch releases at the surface of multiplexer ahead of a connection, then it has a chance of sending a unit into the lane. Similarly, once the switch releases at the surface of de-multiplexer ahead of a connection a chance to receiving a unit from the lane. This procedure is named as interleaving.

4). Statistical TDM

The statistical TDM is applicable to transmit different types of data simultaneously across a single cable. This is frequently used to handle data being transmitted through the network like LAN (or) WAN. The transmission of data can be done from the input devices which are connected to networks like computers, fax machines, printers, etc. The statistical TDM can be used in the settings of telephone switchboards to control the calls. This type of multiplexing is comparable to dynamic bandwidth distribution, and a communication channel is separated into a random data stream number.

Applications of Multiplexing

The applications of multiplexing include the following.

  • Analog Broadcasting
  • Digital Broadcasting
  • Telephony
  • Video Processing
  • Telegraphy

Thus, this is all about what is multiplexing, different types of multiplexing techniques. From the above information finally, we can conclude that by using these types of multiplexing techniques we can transfer and receive the data efficiently. Here is a question for you, what is demultiplexing?

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