Network Connections
Connections between nodes (computing devices, routers, switches) in a network can be of two types:
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Wired connections: As their name suggests, wired connections need a physical wire (also referred to as a cable) between the nodes that need to be connected. The two commonly used types of cables used to connect nodes are:
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Twisted-pair cables: These cables consist of copper wires that are twisted into pairs. They have four pairs of copper wires that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. Twisted-pair cables support very high transmission speeds and bandwidth.
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Optic-fiber cables: These are cables made of glass fibers. The fibers transmit data using pulses of light. Optic-fiber cables have the fastest data transmission rates and the lowest amount of data loss than any other cable. Despite their high performance, the only reason the adoption of options-fiber cables has been slower is their cost and fragility. They are more expensive and less sturdy than twisted-pair cables.
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Wireless connections: Wireless connections use radio signals transmitted through the air and do not need a physical wire to connect devices on a network. This makes it much easier to set up a network since laying cables is an expensive and time-consuming job that needs space for the cables to run through.
Radio Waves
To understand wireless communication, it is necessary to understand radio waves. A radio wave is a type of electromagnetic signal that oscillates at a very high frequency. A radio wave has an amplitude (how high and low it oscillates) and a frequency (how frequently it oscillates). These attributes can be varied in time to represent data, thus making radio waves capable of carrying data through the air.
Radio waves have been in use for many years for various purposes, such as over-the-air broadcast of audio to radio receivers, audio and video to televisions, communication between aircraft and ground control, and more recently, cellular phones. These same radio waves, which are also referred to as Radio Frequency(RF) signals are used for carrying data in a wireless computer network.
RF signals are capable of being transmitted at a very wide range of frequencies (referred to as the electromagnetic spectrum). Since all devices use RF signals through the same medium (the air around us), there needs to be a way for devices to recognize which signal they are expected to send and receive. For this reason, the spectrum is divided into what are known as bands. Each band is allocated for use for a specific purpose.
There are two main types of wireless data communication that we are familiar with: WiFi and Cellular. Both of them use RF signals but at different frequencies in the spectrum. And both of them have different infrastructure requirements. Generally, smartphones that are connected to the cellular network for voice communication use that same wireless connection for data transfer, but they can also connect to a WiFi network. Computers generally do not have the capability to connect to a cellular network and can only use a WiFi infrastructure.
Wireless connections provide high enough data transmission speeds for most users, but are generally slower than wired connections, have a limited range, and physical obstructions, such as walls, can interfere with their transmission. Since the convenience they provide more than makes up for their limitations, they are very widely used in homes, offices, campuses, and even cities.
Since wireless connections have a limited range, they are used only for "last-mile" access. Connections across long distances, for example, two office networks in different cities, or an office connecting to the Internet (via an Internet Service Provider), will have a wired connection between the router at each end. On the other hand, the connectivity from the router to the devices in the home or office network may be wireless.
