Academic Resouce Related to "Computer Networks" (MCA/MSC_IT/BSC_IT)

Concepts of Cell Phone
Mobile phone (also known as a hand phone, cell phone, or cellular telephone) is a small portable radio telephone. Cell phones are defined as sophisticated radios, a type of wireless communication that is used to communicate over long distance without wires. This technology uses many small cells that connect with a nearby base station (also called a "cell site") which connects it to the main phone network. When moving, if the mobile phone gets too far away from the cell it is connected to, that cell sends a message to another cell to tell the new cell to take over the call. This is called a "hand off," and the call continues with the new cell the phone is connected to. The hand-off is done so well and carefully that the user will usually never even know that the call was transferred to another cell.
For example, if you were traveling from New Haven to Rhode Island, your call would be transferred from several based stations along the way. Cellular phones use a short-wave analog or digital telecommunication in which a subscriber has a wireless connection from a mobile telephone to a relatively nearby transmitter and receiver in the base station.

How do mobile phones work?

1). A mobile phone is a two-way radio, as it sends and receives radio signals to and from cell site base stations. For example: Imagine calling a friend on the other side of town. As you chat away, your phone converts your voice into an electrical signal, which is then transmitted as radio waves through air until they reach a base station close by and converted back into sound by your friend’s phone.  A basic mobile phone is therefore little more than a combined radio transmitter and a radio receiver, quite similar to a walkie-talkie or CB radio. 

2). The base station sends the call across the communication network after which the call reaches the intended receiver. A base station in the vicinity of the mobile phone being called sends radio waves for the receiver's device to detect them. The mobile phone of the receiver converts the signals into voice and the phone call is made. 

3). Base stations that form the telephone network for mobile phones are fitted with microwave antennas and are usually mounted on high structures such as a pole or a tower. They have low powered radio transmitters, which relay communication between the mobile phones and the switch. The switch connects the call to other subscribers of the same service provider.

4). When a mobile phone is turned on, it registers with the switch that then alerts the mobile phone of incoming calls. The mobile device listens to the signals being sent by surrounding base stations and switched smoothly between sites. 

5). A device can switch between networks without disturbing an ongoing call by transferring a call from one channel to another. This process is known as a handoff.

6). While you conveniently roam about carrying your mobile phone, the telecommunication network around you is at work, making and maintaining your calls and helping you stay ‘Connected’!

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