Splat | WiseTome.com

Ever wondered why mobile phones are sometimes called ‘cell’ phones? What put the ‘cell’ in the cell-phone?

In case you want to find out, read on.

A cell phone works on the back bone called the cellular network. Hence, the name cell phone - a phone that works on a cellular network. Yes - why is a cellular network called a ‘cell’ network? We will get to that, but before that, let us look at how a call you make from a cell phone to another cell phone work.

When you make a call from your cell, the cell phone transmits a request to the base station of the cell site. It requests for a call to be placed to another cell phone. When the called cell phone is with in its range, then it allots a channel and establishes the connection between the caller and called cell phone (number).

The call proceeds and the channel remains alloted to the call until either of the party breaks the call. When the call ends, the channel goes back to the pool from which the network assigns it to other requested calls.

This was a simple straight forward case. Both the caller and the called were with in the same cell site range. The range depends on the kind of network. If it is GSM network, then the range is around 40 km. If it is CDMA network, then the range is around 60 km. Any network may be the case, but the range is limited. Even a 100 km radius is not sufficient to encompass all the subscribers.

So, what happens when the called number is outside the range of a particular transmitter of a cell site?

This is the general case, where the cellular network comes into picture. Many transmitters are placed so that they cover all the area (with in the geographical scope of a particular mobile telephone company). There may be slight overlaps, but it is seen to it that each point is with in range of at least one transmitter of the network.

Each of the transmitter site is said to be a cell, because when the layout is approximated it looks like the hexagonal cells of honey comb. It is quite possible that the name ‘cell’ was given due to this similarity in structure of the cell site. (I do not have a reference for this - just a hunch).

With such kind of setup, the coverage area of a particular cellular network has increased. The two subscribers can be in any one of the cells of the network. When a call is made, the request is sent to the nearest base station, and the network locates the called cell phone, and eastablishes a channel through a network of transmitters. The different base stations are connected to each other with microwave transmitters, optical cables, or high speed co-ax copper cables.

We have looked at the basic structure that is behind the mobile telephony infrastructure. The actual setup would be much more complex. What happens when a call is made to a land line? What happens when a call is placed to a cell phone who is subscribed to a different network? How are international calls handled? What about call conferencing?

It is a complex world in itself - not just in terms of the technology, but also in terms of business terms.