Splat | WiseTome.com

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.
Read the rest of this entry »

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.
Read the rest of this entry »

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?
Read the rest of this entry »

I have not used Floppy Disks a lot - but I have had my share as I started of my experience with computers in CLIs. Over the years, the scope of data storage from a consumer perspective has grown in scale - from floppy disks to TeraDisks. Not long back, Vinyas had written about Blu Ray disks, and now Sourjya writes about TeraDisks in the near future.

Let us look at how the storage was used by people, how they are used presently, and what would the TeraDisk mean in that perspective.

Floppy Disks

There were two types of floppy disks. The partially flexible 5.2″ floppy disks that could store 1.2 MB of data. And then, there was the 3.2″ floppy disk that could store 1.4 MB which came in a sturdy plastic casing. This was quite enough during those times (back in late 90s) when the OS could be booted out of a floppy disk. It was quite sufficeint for the restricted consumer market. At most, it was used for storing RTF (Rich Text Formatted) documents, and spread sheets. The more common use was to store documents in vanilla ASCII format. The The Adventures of Sherlock Holmes by Sir Arthur Conan Doyle amounts to just around 576 kB and contains 12 novels. This is not the usual size of the documents that people would work with. It would range around 1 kB to 10 kB. That meant, one could store around 100 documents in a single floppy disk.
Read the rest of this entry »

Yes - we are all in a rather excited mood after engadget reported that iPhone could be unlocked and we could use other SIMs than that provided by AT&T. I am not a iPhone user, and I do not much care about it. But it made me remember of the days as communication engineering student, and I thought I would share it here.

What is SIM?

SIM or Subscriber Identity Module is a IC (Intergrated Circuit) chip that is used to identify a GSM subscriber with in a network. GSM is considered the second generation in mobile phone telephony protocol - more on that in a later post.

Pushing aside all these technical lingo aside, what does this mean to us users? SIM allows us to change a phone - the device without changing our number, with out changing our subscription to a particular network. It also means that, it allows us to change our network and still keep using our phone.
Read the rest of this entry »

Social Networking Sites, as much as they build bridges between people, also are a cause for deterioration of behavior of the community as a whole.

It is basically not just Social Networking Sites, but any site that foster interaction between people - is a place where community behavior could take the wrong turn.

Could you imagine how in appropriate it is, for people in real life, when they meet each other in person, in a public place to rant out ‘colorful’ words at each other? From the mild ‘you suck’ to anything highly profane - uttered in public would be ridiculed. It is not that people do not use such words at all - but it is acceptable in some places. Say a intoxicated people in a drinking place, or may be on a free form wrestling ring.

The anonymity or the layer of insulation that the internet gives is sufficient for the people to go over the edge. It takes all forms and shapes - and is quite amusing to study. Even credible people cringe at the thought of the Digg userbase. It does not take long for a userbase to turn into a mob. All rationality is thrown to the winds and what remains is something that is much closer to a deranged beast.

Of course, I have made a lot more friends online than the times I have had to face such nuisance. But I have to admit that the chances that you run into a person with retarded behavior is much more than your neighbor being a psycho killer. (No, it is not based on any statistics )