I have tried to explain the concepts of data communication and computer networks, identify different components of a compute network, explain the protocols involve in the communication and understand the different types of the network communication such as LAN, WAN, wireless transmission, radio transmission and satellite communication. The basic elements of the communicating system are sender, medium and receiver. In data transmission these four elements are frequently used such as data, signals, signaling and transmission. A computer network is consisting of two or more computers connected together using a telecommunication system for sharing data and resources.
It is very interesting to know that how computers send and receive the information across the communication links. Computers do this job by the help of data communication software. It is software that enables computers to communicate with each other. The data transmission software tells the devices and computers how to send information to the other computers. The software that is used for the data transmission is known as protocol. The data transmission software or protocols perform the following basic functions.
1. Data sequencing: A long message is broken up into the smaller packets of fixed size for the error free transmission.
2. Data Routing: In the data routing process the most efficient route is to find to send the data from the source to the destination.
3. Flow control: The flow control regulates the process of sending data between fast sender and slow receiver.
4. Error Control: Error detection and recovery is the most important factor of the data transmission software (protocols). It ensures the error free transmission of the data.
Data Transmission Modes
There are three basic steps of transmitting the data from one point to another.
1. Simplex: In the simplex mode of the transmission the communication takes place only in one direction and the receiver receives the signals in one direction this is also known as uni-directional transmission
2. Half-duplex: In half duplex mode of transmission signals are sent in both directions but one direction at a time so half duplex lines can alternatively send and receive data.
3. Full-duplex: In the full duplex transmission mode the communication channels is used to send and receive the data in both directions at the same time. Example of this kind of transmission is the telephone lines.
The following are the basic types of the computer networking and transmission.
LAN stands for the local area network and it represents a small or a large area such as a building, school or a small office. All the computers in a LAN are connected with each other and they can access each other. LAN is normally accommodated within the small area. All the computers in a common type of LAN are connected with a central device known as a hub or a switch. As the number of the LAN’s computers increase the speed tends to decrease in the LAN. LAN computers can be wired or wireless.
WAN or wide area network is types of computer network that covers a large geographical area and that is usually consisting of two or smaller computer networks. The internet is a type of a WAN. The LAN networks can be publically or privately owned. There are a number of WAN technologies used:
• Point-to-point links – point to point links connect the customer’s premises to the main network through a telephone line.
• WAN devices – There are a number of the WAN devices such as routers, switches, modems, ATM switches, access servers and ISDN adapters.
• Packet switching – In this type the customer’s share carrier’s network. The cost is usually cheaper for the customers.
• Circuit switching – in this type the data transmission is initiated when it is needed and stopped what it is not needed. ISDN is an example of the circuit switching network. It is more reliable and fast communication type.
• WAN virtual circuits –This is a shared network with two or more other networks.
• WAN dial-up services – It is a very cheap way to initializing a network and it uses telephone line to connect the internet
The internet is a world’s largest publically accessible network of interconnected computer networks that sends the data by the packet switching and by using the standard internet protocol. Internet consists of millions of smaller, domestic, academic, business, governments and publically owned networks. The interconnected computers on the internet carry various types of information such as web pages, emails, news, music, video, images and data. In recent years, mobile internet, either through wireless USB dongles or mobile phones, has also become popular.
Public Switched network
The public switched network or PSTN is a network of world’s public circuit-switched telephone network in the same way as the internet is a network of world’s IP based networks. PSTN is now a digital system and includes mobile and fixed telephones.
Telecommunication is the process of transmission of signals over a large distance for the purpose of transmission. This process normally involves sending of the electromagnetic waves by electronic transmitters. Telecommunication is the process of communication for television, radio and telephones. Computer data transmission across the internet is a type of the telecommunication. Telecommunication systems are generally designed by the telecommunication engineers. In the recent time the fiber optic cables have radically increased the bandwidth for the transmission channels.
Wireless Networks are the computer networks that communicate through the use of the radio waves and the current standard for this the IEEE 802.11 x standard, which is also, called Wi-Fi. Currently there are three Wi-Fi standards a, b and g and n and i standards are currently being in the development phase. 802.11b was the first wi-fi standard and has a maximum speed of 11 Mbps.
1. Infrared Transmission- It sends the data signals using the infrared-light waves at a frequency which is too low for human eyes. Infrared ports can be found in the digital cameras, laptops, and printers
2. Broadcast Radio- A wireless transmission medium that sends data over the long distances such as regions and countries upto 2 MB per second such as FM and AM radio.
3. Microwave Radio- It transmits voice and data at 45 MB per second by using the radio waves
4. Communications Satellites- These are the microwave relay stations in the orbit around the earth.
5. Bluetooth- Bluetooth is a wireless short range transmission specification and it was supported by a large number of the communication companies such as Nokia, Erickson, Intel and IBM. The range of the Bluetooth is 10 meters and it supports voice and data transmission at a rate of up to 1Mbps with the frequency range of 2.4 to 2.48 GHz. Bluetooth is a radio technology which works even in the areas of electromagnetic disturbances.
A communication satellite is an artificial satellite station in space for the purpose of telecommunication. There are several types of the satellites such as astronomical, communication, earth observation, navigational satellites, reconnaissance satellites, solar power satellites, space stations and weather satellites.
Applications of Satellites
There are different applications of the satellite such as telephony, television and radio, direct broadcast satellite, fixed service satellite, mobile satellite technologies, satellite and broadband service.