1.4 Modes of Data Communication (Simplex, Half-Duplex, Full Duplex).

Transmission Modes in Computer Networks (Simplex, Half-Duplex and Full-Duplex)

  • Transmission mode means transferring of data between two devices. It is also known as communication mode. Buses and networks are designed to allow communication to occur between individual devices that are interconnected. There are three types of transmission mode:- 


These are explained as following below.

1. Simplex Mode –
In Simplex mode, the communication is unidirectional, as on a one-way street. Only one of the two devices on a link can transmit, the other can only receive. The simplex mode can use the entire capacity of the channel to send data in one direction. 
Example: Keyboard and traditional monitors. The keyboard can only introduce input, the monitor can only give the output. 




2. Half-Duplex Mode –
In half-duplex mode, each station can both transmit and receive, but not at the same time. When one device is sending, the other can only receive, and vice versa. The half-duplex mode is used in cases where there is no need for communication in both direction at the same time. The entire capacity of the channel can be utilized for each direction. 
Example: Walkie- talkie in which message is sent one at a time and messages are sent in both the directions. 

Channel capacity=Bandwidth * Propagation Delay

3. Full-Duplex Mode –
In full-duplex mode, both stations can transmit and receive simultaneously. In full_duplex mode, signals going in one direction share the capacity of the link with signals going in other direction, this sharing can occur in two ways: 

  • Either the link must contain two physically separate transmission paths, one for sending and other for receiving. 
  • Or the capacity is divided between signals travelling in both directions. 
     

Full-duplex mode is used when communication in both direction is required all the time. The capacity of the channel, however must be divided between the two directions. 
Example: Telephone Network in which there is communication between two persons by a telephone line, through which both can talk and listen at the same time. 

Channel Capacity=2* Bandwidth*propagation Delay


References- Data Communication and Network,5th Edition,Behrouz A.Forouzan.

Comments

Post a Comment

Popular posts from this blog

2.1 Guided Media : Twisted Pair -UTP, STP; Coaxial Cable Optical Fiber

Image
  Guided media, which are those that provide a conduit from one device to another, include   Twisted-Pair Cable ,   Coaxial Cable , and   Fibre-Optic Cable . A signal travelling along any of these media is directed and contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic (copper) conductors that accept and transport signals in the form of electric current.  Optical fibre  is a cable that accepts and transports signals in the form of light. Twisted Pair Cable This cable is the most commonly used and is cheaper than others. It is lightweight, cheap, can be installed easily, and they support many different types of network. Some important points : Its frequency range is 0 to 3.5 kHz. Typical attenuation is 0.2 dB/Km @ 1kHz. Typical delay is 50 µs/km. Repeater spacing is 2km. A twisted pair consists of two conductors(normally copper), each with its own plastic insulation, twisted together. One of these wires is used to carry signals to the receiver, a
Read more

2.2 Un-Guided Media: Wireless Communication Infrared Communication Microwave Communication

Image
Unguided medium transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Signals are normally broadcast through free space and thus are available to anyone who has a device capable of receiving them. The below figure shows the part of the electromagnetic spectrum, ranging from 3 kHz to 900 THz, used for wireless communication. Unguided signals can travel from the source to the destination in several ways:  Gound propagation ,  Sky propagation  and  Line-of-sight propagation  as shown in below figure. Propagation Modes Ground Propagation:  In this, radio waves travel through the lowest portion of the atmosphere, hugging the Earth. These low-frequency signals emanate in all directions from the transmitting antenna and follow the curvature of the planet. Sky Propagation:  In this, higher-frequency radio waves radiate upward into the ionosphere where they are reflected back to Earth. This type of transmis
Read more

1.6 Classifying Networks by their Component Role : Peer to Peer, Server based Network

Image
The two types of network architectures are used: Computer Network Architecture Peer-To-Peer network Client/Server network Peer-To-Peer network Peer-To-Peer network is a network in which all the computers are linked together with equal privilege and responsibilities for processing the data. Peer-To-Peer network is useful for small environments, usually up to 10 computers. Peer-To-Peer network has no dedicated server. Special permissions are assigned to each computer for sharing the resources, but this can lead to a problem if the computer with the resource is down. Advantages Of Peer-To-Peer Network: It is less costly as it does not contain any dedicated server. If one computer stops working but, other computers will not stop working. It is easy to set up and maintain as each computer manages itself. Disadvantages Of Peer-To-Peer Network: In the case of Peer-To-Peer network, it does not contain the centralized system . Therefore, it cannot back up the data as the data is different in di
Read more