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In the last post on cellular network, you saw that the geographic area of a cell phone service provider is divided into cells - roughly hexagonal shaped areas that serve a particular region. The cell site provides coverage for that particular cell area. This results in the use of quite an interesting technique called handoff.

What happens when the caller (or the called) travels from one cell to the adjacent during a call? How does the network handle it? How does the network know which cellular network tower should be used to keep the connection between the caller and the called in order to continue the call?

The SIM card in a cell phone will be constantly identifying its location back to the tower. It will be keeping track of it and storing it in the LAI. A combination of the location and the usually the strength of the signals from the adjacent towers, helps the network make a handoff of the call. The moment a caller crosses the imaginary boundary of a cell and enters an adjacent one, handoff takes place, and the tower of the entered cell starts to handle the call.
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It has been not long back that Google made a move to acquire DoubleClick. This sent waves of different emotions through out the blogosphere and internet in general. Google has been grown to such an extent under such a short time, that it is faced with quite a varied palette of reactions for every action it takes.

And it was not long before Microsoft hedged to have the officials look into the Google DoubleClick acquisition under the scrutiny of Antitrust Laws.

Antitrust Laws in United States

Antitrust Laws in United States prohibits monopoly (or anti-competitive behavior) and condemns unfair business practices. The antitrust laws seek to protect the consumers. If a particular company is able to set itself in a monopoly position, it can change the prices and the supply at its own whim, since it is not driven to deliver quality service/products in order to compete with its competitors.

History Of Antitrust Cases

United States has seen its share of Antitrust cases filed against several companies in this decade.
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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?
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