In a network, a communication channel or media is a connection between transmitter and receiver through which transmission signals travel. A communication channel ensures computer connections and transmission of information in a network. Types of communication channels are Guided Media, Unguided Media.
What is Communication Channel?
Communication channel also known as communication media or transmission media is a path that connects the sender and receiver for transmission of information over a network. Common examples of transmission media are Twisted pair, Coaxial cable, Fiber optics & Satellite, etc.
What is Communication Model?
A model is simply a visual presentation that identifies, classifies and defines various parts of a communication process. It allows us to see specific concepts and steps within the process of communication. The simple communication model consists of a sender, message and receiver.
Communication Channels Design Factors
- Bandwidth:- Total amount of data that can be transferred through a communication medium in a unit of time. Higher bandwidth produced a higher data rate. Digital signals bandwidth is always measured in bits per second or bytes per second and analog signals bandwidth is measured in cycles/Seconds or Hertz also.
- Transmission impairments
- Number of receivers introduces more attenuation
Types Of communication Channels
A communication channel or transmission media is a path that connects the sender and receiver for transmission of information over a network. A communication channel ensures computer connections and transmission of information in a network. Types of communication channels are Guided Media, Unguided Media.
Guided or Physical Transmission Media
In guided transmission media, communication devices are directly connected with each other via wires or physical media for data transmission. Guided media is also known as bounded media because the data signals are enclosed to a cabling media. The guided media is mostly used in LAN.
Some examples of bounded media for communication are as follows:
- Twisted Pair Wire
- Coaxial Cable
- Fiber Optics
Twisted Pair Wire
Twisted pair wire is the most commonly used communication media in LAN (Local Area Network) for data communication among the computers. Normally, the twisted pair wires are used in local telephone lines to carry voice and data signals
This cable is almost made up of copper coated with an insulating material like plastic. The pair of wires are twisted together in order to reduce noise. The electrical disturbance that can degrade the communications is called noise.
In addition, the data transmission speed of the twisted pair wire is near about 9600 bits per second at a distance of 100 meters. Twisted pair is inexpensive and has less speed than coaxial cable or fiber optics.
Coaxial cable is also termed as coax. It carries high-frequency range signals than twisted-pair cable. It is made up of a single solid copper wire core that is covered by insulating material. A copper mesh is used to cover the insulated copper wire. It also protects the cable from electromagnetic waves.
Coaxial cable is the same cable that is used for television. This cable is used for long-distance telephone lines and local area networks for voice and data transmission with very high frequency. Coaxial cable bandwidth is 80 times higher than the twisted-pair wire. So, it is more expensive than twisted pair.
Fiber optics is also known as light pulse media. It uses a binary method of data transfer. Fiber is made up of thin glass fiber. A fiber optics consists of a very narrow fiber of glass called the core. It is thinner than a human hair. There is no possibility of data loss.
In addition, the best advantage of fiber optics is that data is already in binary form and it just needs to be converted into light only. It can transmit data up to billions of bits per second. The main disadvantage of fiber optics is that it is very expensive and also difficult to install and modify.
Fiber Optics cable is used for
- Internet services
- Long-distance communication
- Local area network
Unguided or Wireless Transmission Media
The communication devices in unbounded communication channels /media communicate with each other through air or space using broadcast radio signals, microwave signals and infrared signals as a medium. Unbounded media can also be used at each and every place where it is impossible to install cables. The best solution is to use unbounded media.
Data can be transferred to each and every place in the world by using unbounded media. Some examples of unbounded communication channels are as follows:
- Microwave System
- Communication Satellite
- Broadcast Radio
- Cellular Radio
Microwaves are radio waves that are used to provide high-speed transmission. The user can also transmit both voice and data through microwaves. From one microwave station to another data is transmitted through the air similar to radio signals. The microwave uses line-of-sight transmission.
Line-of-sight transmission means that the signals travel in straightway and cannot bend. The microwave uses line-of-sight transmission. Sight transmission means that the signals travel in straightway and cannot bend. The microwave stations or antennas are usually installed on tall towers or buildings.
Microwave stations are placed within 20-30 miles to each other. Each station receives the signals being transferred by the previous station and then transfer these signals to the next station. This is the way how data is transferred from one place to another.
However, It is almost necessary to keep in mind that there should be no buildings or mountains between microwave stations.
Communication Satellite is a space station. It receives microwave signals from the earth station. Communication satellites magnify the signals and retransmit them back to earth. The communication satellite is established in space that is very far near about 22,300 miles above the earth.
In addition, The data transfer speed of the communication satellite is very high. The transmission from the earth station to a satellite is called uplink. The transmission from the satellite to the earth station is called the downlink.
Broadcast radio is a wireless transmission medium. It distributes radio signals through the air over long and short distances. Radio transmission requires a transmitter to send broadcast radio signals and a receiver to receive it. The receiver uses an antenna to receive the signals.
Some networks use the transceiver that can both send and receive signals. An example of the short-range broadcast radio communications is Bluetooth. It uses short-range radio waves to transmit data at a rate of 1 Mbps among Bluetooth enabled devices.
In addition, Bluetooth is used in personal computers, internet appliances, cellular phones, fax machines, and printers also.
Cellular radio is a broadcast radio that is used for mobile communications. It is specifically used in wireless modems and cellular telephones. The cellular telephone is also a telephone device that uses high-frequency radio waves to transmit voice and digital data.
However, some mobile users connect notebooks or mobile computers to the cellular telephone to access the Web or send and receive the email, etc. Personal Communications Services (PCS) is a set of technologies used for digital cellular devices like Handheld computers, cellular telephones, etc.
Infrared (IR) is a wireless transmission media. It sends signals using infrared light waves. it requires a light –of –sight transmission. IrDA port is normally fixed in mouse, printer, and digital camera in order to enable them to transfer data from one device to another using infrared light waves.
It is also an alternative to short-range raid communication like Bluetooth.