How a Cellular Network Works!!!


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Cellphones really changed the world over, right from how we communicate, to how we socialize with modern times. But have you ever wondered how a Cellphone Network really works? Let's find out!!!


Basics:

Your Zenfone is really a radio transmitter in all basic sense. It can transmit and recieve. But the transmission and reception of all cellular mobile conforms to rules laid out by a global forum called GSM. GSM has laid out a format and technology template for all communication to happen. 


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Cell in a network is a immovable transreciever, technically called as a "Base Transciever Station (BSS)", commonly known as mobile towers in layman terms. This is called as a cell because hypothetically the range covered by a cell is in an hexagonal shape.

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So if you club multiple such stations..it would form a cell-like network....A cellular network. Each cell border actually overlaps each other, and they also connect to the regular wired telephone network through a Base Station Controller subsystem. Each Cell has a unique ID to distinguish itself from others.


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Mobile handsets, such as your Zenfone is technically called a Mobile Station, so you'd probly know that this device is meant to be 'mobile' and one that travels between and across the Cellular network. A Mobile as you know can transmit and as well as receive voice and data, so its very much like a 2-Way Radio.


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mobile handset consists of a low power transmitter and a reciever, and by low power I mean really really low, from0.3 to 3 watts; if you compare it with AM Broadcast transmitters (One that you tune into on your Radio reciever), these transmit with a power in excess of 50,000watts. Also, ideally your phone has a limited low voltage battery pack, so its neccessary that these transmitters and recievers work with very low power consumption.

How it works:

Whenever you turn on your device, your phone without you knowing broadcasts a message pertaining to your SIM identification. This message is picked up by the Base Station/Cell tower. The tower registers you phone as a Home user or a Visitor User based on your SIM information. The tower actually maintains 2 separate registers - A Home Location Register(HLR) and a Visitor Location Register (VLR)


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HLR:HLR keeps essential subscriber information such as Address, User accounts and User preferences. Every tower maintains this register to maintain User Information of a User/Subscriber that is native to a city/location the tower is in.

VLR:
This is more of a temporary regisiter that maintains active list of subscibers that are in its vicinity. It mainly keeps a list of users that are away from its home location.


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Making and recieving calls while Stationery:

When make a call to your friend, your phone first contacts the tower closest in range to you. The service registers (HLR and VLR) exchange information about you, regarding where you are and which route is the easiest to reach your friend, and also checks if you're eligible to make that call based on your location and account. Once a route is set, it then directs the call to the Mobile tower that the reciever is closest to him and rings his phone.


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Recieving the call is similar too. If a friend makes a call to you, his phone first transmits to a tower closest to him, that tower contacts your home location station, and the station then sends in the location where you're currently at. The call is then routed with the shortest least & busy path to tower which you are around and rings your phone.


What if you're mobile???

It's pretty hard for the networks to hunt you down when you're moving about between tower to tower at highspeeds. In this case the towers between which you're transitioning actually 'hands-over' active calls from one tower to the other. This "handing over" of signals is acheieved with 'frequency hopping' and other complex techniques. Even when you're not in active calls, your Phone constantly is sending out signals to towers around you when it knows the signal is about to drop dead. 


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With each new tower you register withit forms a route pattern of where you are, this makes it easier to know where you are. And the route to you is shortened if the network systems finds a more easier and faster route.

So, Pretty simple right?

Understanding cellular networks in detail is pretty complex as there are tons of entities that makes everything work. It even involves satellite communication too if you're in another country or state, which means between tower to tower, a satellite link is required to make a distant call possible

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All these operations happen under couple of seconds, incredible right??? However there is so much more to talk about... Stay tuned in for more on Mobile Networks!!! 

*Article by Zen_Ro from ZenTalk.

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