Comprehensive Study Guide to Communication Media and Computer Networking
Types of Wireless and Unguided Communication Media
Bluetooth Communication: Bluetooth is a wireless technology that utilizes wavelength to transmit data among connected devices over short-distance ranges.
Infrared (IR) Communication: Infrared is a wireless mobile technology characterized by wavelengths that are longer than those of visible light; because of this, the IR signal is invisible to the human eye. This technology is primarily used for communication between devices over short ranges.
Cellular Communication: Cellular technology is a wireless network system that facilitates communications over specific geographic areas composed of cells and transceivers. These transceivers are referred to as cell sites. The most commonly utilized transceivers in this system are mobile phones or cell phones.
Satellite Communication: This refers to the use of satellite technology to facilitate communications. Satellite services include:
Voice calling.
Video calling.
Internet access.
Faxing.
Television and radio channels.
Operational Process: A local site uses an antenna to send and receive data signals. These signals are communicated to or from a ground station. The ground station, in turn, exchanges data with a satellite orbiting the Earth.
WiFi (Wireless Fidelity): WiFi is high-speed internet and network connectivity achieved without wires or cables. It utilizes radio waves to establish connections between a sender and a receiver.
How WiFi Works:
A radiofrequency current is supplied to the antenna.
An electromagnetic field is generated and broadcasted through space.
A network Access Point (AP) serves as the foundation for the wireless network, broadcasting a signal that computers can detect and tune into.
To connect, computers must have wireless network adapters (hardware that facilitates WiFi and Bluetooth connectivity).
Adapters translate binary data into radio signals and transmit them via the antenna.
Finalizing the cycle, a router receives these signals, decodes them, and transmits the information to the internet using a physical wired Ethernet connection. This process also operates in reverse.
LiFi (Light Fidelity): LiFi is a wireless system that transmits data using light instead of radiofrequency. It requires a light source (currently LEDs) and a chip to transmit data over visible light.
Advantages: It offers speeds of approximately , is interference-free, and is more secure than radio-based technologies like WiFi or cellular.
Types of Physical and Guided Communication Media
Twisted Pair: This is the standard copper wire used for telephone communications and most modern Ethernet networks. The pair of wires forms a circuit for data transmission.
Unshielded Twisted Pair (UTP): A common type of twisted pair cabling.
Shielded Twisted Pair (STP): A variation of twisted pair with additional shielding to protect against interference.
Coaxial Cable: An electrical cable consisting of an inner conductor surrounded by an insulating layer, which is itself surrounded by conductive shielding. This design allows for fast data transmission protected from external damage or interference.
Applications: Frequently called Radio Frequency (RF) cables, they connect radio transmitters and receivers with antennas, and are used for internet connections, digital audio, and cable television signals.
Fiber Optics: These are network cables containing strands of glass fibers inside an insulated casing. They are designed for long-distance telecommunications with high performance and speed.
Mechanism: Communication signals are carried using pulses of light generated by small lasers or light-emitting diodes (LEDs).
Components: Glass core, Plastic Jacket, and Insulated casing.
Network Terminologies and Classifications
PAN (Personal Area Network): Connects devices within a user's personal immediate space, ranging from centimeters to meters.
Example: A Bluetooth connection between mobile phones and headphones. While PANs don't connect directly to the internet, they can connect to other networks that do.
LAN (Local Area Network): A network contained within a small geographic area, such as a single building, a university campus, or a laboratory.
Example: A home WiFi network.
MAN (Metropolitan Area Network): A network connecting computers within a metropolitan area, such as one large city or several cities and districts. It is spatially larger than a LAN but smaller than a WAN.
WAN (Wide Area Network): A large-scale telecommunication network covering vast distances. Businesses often use WANs to link different offices, where each office has a LAN that connects to others via the WAN.
Example: The internet is considered the largest WAN.
Private Network: A connection with limited access where only selected devices can join based on encoding settings in access points and routers. Devices outside the network cannot access it.
Example: Bank employees are the only people authorized to access a bank's private network.
VPN (Virtual Private Network): A private network that utilizes public infrastructure, specifically the internet. It provides a secure, reliable link between computer networks over public space, appearing as a private link to the user.
Example: Employees working in different geographic areas use a VPN to access a single company network.
Server: A computer responsible for managing network resources including hardware, storage, and files. It "serves" other computers (clients) on the network, allowing information sharing without physical transfer.
Client: A personal computer on the network that utilizes the services provided by the server.
Data Communication System Components
Message: The core of the communication system; it is the data or information to be communicated. It can take any form, such as text, audio, or images.
Sender: The device that originates and sends the message (e.g., tablet, mobile phone, computer).
Receiver: The destination device where the message arrives (e.g., tablet, mobile phone, computer).
Transmission Medium: The bridge or path between the sender and receiver. This can be guided (wired cables) or unguided (wireless radio waves or microwaves).
Set of Rules (Protocols): These are the rules governing the communication between devices. They represent a technical agreement between devices designed by the communication system's creators.
Fundamental Concepts of Networking
Definition of a Computer Network: A collection of two or more computers linked together to exchange files, interact securely, and share resources such as folders and printers. Networks can span a room, a building, a street, or the entire globe.
The Internet: Defined as the "network of networks," it is the global web of linked computer networks.
The Purpose of Computer Networks:
Sharing internet connections.
Sharing hardware (scanners, printers, input devices).
Sharing data and information via shared storage devices.
Sharing software by running applications on remote computers.
Packets: Data sent over a network is not sent as a single block; rather, it is broken down into small parts referred to as "packets."