Comparison of Different Wireless Interface - 802.11 a/b/g/n

IEEE 802.11 is a set of standards for carrying out WLAN communication. Simply put, IEEE 802.11 specifies the way and means by which we can communicate on wireless networks. These usually operate at frequency bands of 2.4, 3.6 and 5.0 GHz. these standards are created and maintained by the IEEE LAN/MAN Standards Committee.

The table given below compares the standards:

802.11 Protocol	Freq. (GHz)	Bandwidth (MHz)	Data rate per stream (Mbit/s)	Allowable MIMO streams	Approximate indoor range (m)	Approximate Outdoor range (m)
1997	2.4	20	1, 2	1	20	100
a	5 / 3.7	20	6 - 54	1	35/--	120 / 16,000
b	2.4	20	5.5 - 11	1	38	140
g	2.4	20	6 - 54	1	38	140
n	2.4 / 5	20 / 40	7.2 - 72.2 / 15 - 150	4	70	250

Without considering the 3.7 GHz 802.11a band (the use of which is highly restricted by the Federal Communications Commission), we can see that 802.11n is the clear winner in terms of both range and speed. Also, 802.11n has a 5 GHz version, which takes care of the microwave interference problem. However, because of its high cost and low availability (in India), we generally use 802.11g as an alternative.

The microwave problem: Since 802.11b and g both operate in the 2.4 GHz band, they may experience interference whenever devices using the same frequency are operated near them. To describe it simply, this frequency band is like a one-lane road, and can only allow one-way traffic. So, when we operate, say, a microwave in the vicinity, we have to allow the "data" being transmitted by the microwave to transmit before our own wireless connection can operate. The microwave problem can reduce speed by 70 - 80%.

It was a pleasure to do our project, as it helped explain the differences between the interfaces, and which would be most suitable for different conditions. We thoroughly enjoyed doing the project, and would like to thank Dr. Amarjeet Singh for providing us with this opportunity.

Amol Verma

Paritosh Mittal

Vinayak Chopra

Fifteen years of 'Exploring' the Internet

Ok so now just yesterday my grandpa wanted to use the net for booking his flight ticket and I opened up the Chrome browser for him. Instead he asked me to open up Internet Explorer. When I asked him the reason for him preferring IE, he told me that it allows him to surf the Web with minimum fuss. It seemed at that moment as if the long neglected icon of the Internet Explorer in my taskbar was indeed smiling at me. It was then that I realized that you may love it or hate it, but you simply cannot ignore it.

It’s been 15 years since Microsoft launched the IE; to be precise it was launched about a month after the launch of Windows95. With 60 percent of the world’s netizens using IE even after 15 years of its launch, it’s evident that its popularity refuses to die down. This despite the fact that its rivals like Google, Mozilla and Apple were offering better browsers.

Now a bit about its history and its different versions.

When IE first appeared in 1995, the main software that people used to browse websites was Netscape. Now IE’s first version was based on a browser of that period known as Mosaic. It did not come integrated with Windows. A very basic browser, it had a greyish background. The image below shows just how it used to look:

The main shift came with the Microsoft launching IE3 in 1996. The BlueE logo was also introduced. It supported cascading style sheets (CSS) and came with features like mail, news and an address book. It had support for GIF and JPEG files also. Also unlike Netscape, IE was free for all users. IE 4 was released in 1997 and was part of Windows 98 and had the tag line “the Web the way you want it”.

IE5 had new search and history features as well as support for bi-directional text. Bi-directional text is text containing text in both text directionalities, both right-to-left (RTL) and left-to-right (LTR). By the time IE6 released IE’s market share had grown to 90 percent. It was however at the same time that it was ridiculed for weak security and clunky surfing experience.

The launch of IE 7 was significant in the sense that tabbed browsing finally came to IE. It also included a separate search bar and support for RSS (Really Simple Syndication).

IE 8 had features like new tools such as Web Slices and Accelerator.

Agreed that IE was late off the mark in terms of features like tabbed browsing and add-ons, seen much earlier in other browsers. Also being the most popular browser made it more vulnerable to attack by hackers. This is not to say that other browsers don’t have such issues but any problem with IE tends to get highlighted.

This said , I feel that one can not deny the contribution that IE has made to the internet. And frankly had it not been for its so easy accessibility, the count of netizens in the world might not have been at the same level as they are today because it was the IE that allowed people to use the internet as easily or “without fuss” as my grandpa pointed today.

As a matter of fact while filling the IIIT-D form; it was with IE that it finally got downloadedJ. Not just IIIT-D, there are several websites that recommend us to view them in IE. Maybe slow off the mark, but it definitely has not stopped improving. And an old proverb that goes like this

" Slow and steady wins the race ".

Many happy returns of the web, IE

Image Editing Tools: Experiences- good & bad!

It was a great experience working on SM project. Shreyasi, Jahnavi & I decided upon this topic because playing with images seemed interesting. And in the end, it turned out to be even more interesting than we had thought! :)

The software we chose was Ulead PhotoImpact X3. We selected this because it is free, quite user friendly and provides large number of features. And its relatively unheard and unused as compared to Adobe Photoshop, so we were more enthusiastic to explore its features.

We demonstrated our project using 3 videos which showed use of various tools such as clone, blur, smudge, transform, etc.
Various processes we demonstrated were:
Video 1 - Resizing and multi-layering of three images.
Video 2 - Improving upon facial features of an old lady.
Video 3 - Cloning parts of different images into one.

There were various challenges in completing this project. It was difficult to find a free full motion recorder without watermark. The biggest challenge was to make project videos without any major mistake. We had to make each video at least 5 times to make them presentable. And even after that, some people questioned "Did you actually make these videos? Really? Seriously they are not from youtube?" :/

But it was an awesome experience- staying in college till late in evenings... working in group (with a bit of T.T. in between). Rather lots of T.T. with a bit of work in between! :D

The last few days before the presentation day were most hectic. Mailing the lab handout. Fixing time with others for lab training session. Completing the presentation. Practicing it.

Then came the presentation day. Nervous! But as the presentation moved on, confidence level rose.

But all is well that ends well. So in short, it was a nice experience- full of fun.
Thanks to Amarjeet sir for providing us with such an opportunity! :)

Nikita Juneja 2010057
Shreyasi Agrawal 2010080
Jahnavi Kalyani 2010032

Lab Session 9

I apologize for being late in writing this blog. Me and my partner Priyanka had an amazing experience.

First comes the training part (for which priyanka came straight from airport after CWG vacations).Only part that was time consuming was latex. It was like learning a new coding language all of a sudden.We had lots of queries as to why and how we have cover it in the lab because how can anyone expect us to learn the syntax in a single day. So we ended up learning the basics of it (though we were afraid as to what all and in what depth our group members may ask us about it?).

And ya, the trainers for web crawling were absent that day, so we missed that part.But thankfully Shayan tought us that on Monday during break. But overall, the training part went off well. The topics that we covered were:

• Web Crawling :We covered topics like visualizing a part of the web as a graph, save pages to disk, concatenate pages for printing, extract images from a set of pages.This was the part which seemed new to everyone.So, all of them were listening with patience and interest.
• Data recovery from mistakenly lost files: We used a software called PCrecovery.This task took some time because we first had to install this software in each PC.
• Shredding in Ubuntu : Very interesting and easy to understand.Actually the way kashish gave its training, it became crystal clear to all the leaders!:) 
• Latex : Making PDFs seemed interesting to all.But not too much formatting could be done while making the PDFs as we covered only basic commands.
• Backingup data : Windows has an inbuilt utility for backingup data whereas in Linux, we installed an application.                         

But anyways, the overall experience was very informative. I wasn't thorough with one of the topics but Priyanka proved to be a good co-leader and my group members too were very cooperative ;-) (in contrast to what i was expecting ). 

Thank You Sir for giving us a chance to experience of learning and then teaching.

We look forward to see other professors  try such innovative things so that learning becomes interesting.:)

ROLLTOPS-new generation laptops

My dream to roll my laptop seems come through , as i saw Orkin Design's for roll top laptop.The device has flexible display & allows a new concept in notebook design growing out of the traditional one.The major difference between a laptop and a rolltop is the physical structure. Unlike a laptop's two-fold, book-like appearance, one needs to unfurl the rolltop. It appears rounded when closed.This exact feature makes it totally bankable for computer enthusiasts. Business people and other computer users may now carry their computers.It has OLED-Display technology and a multi touch screen .Screen is of 13 inches transforms into the "graphics tablet," which serves as the primary monitor. Computer accessories in a rolltop are all integrated making it an "all-in-one gadget." This quality extends from the power supply through the "holding belt" up to its stylus or piece of interactive pen.

Presentation on Tools for Web Crawling

We had initially tried to select 2 other topics but finally settled for this topic as those 2 topics had already been taken by the other groups(We don't remember which topics they were).
Initially we didn't like it as we thought this topic wouldn't have much information that we could learn and share with our classmates but over the course of our research, we found out that we were VERY much wrong! There was so much to learn and we had to decide what could be shared with the class without getting them confused as web crawling involved understanding the code that web crawlers use for crawling the web in their search for information.

In our presentation, we covered the definition of a web crawler, types of web crawlers, examples of known web crawlers and also gave a demonstration of two of them(one written by us)

There are 4 types of web crawlers - search engine crawlers, email harvesting crawlers, corporate crawlers and specialised crawlers.
Three examples of known web crawlers that we covered were Websphinx, Universe(Which we decided not to cover in the presentation) and python crawler(which as mentioned before, we made). We decided to make the web crawler using python as we had covered python in class and we found it easier to understand the logic behind the crawler than compared to if we had tried to do it using Java.

In the end, we enjoyed making this presentation and practising amongst ourselves to try and deliver that perfect presentation despite running into hurdles like spending 2 weeks away from each other due to the CWG break, understanding how the web crawler works using python coding, etc.


Samiran Roy (2010073)
Shayan Lahiri (2010078)
Apoorv Saini (2010020)

Remote Connection to a Machine

Remote Connection to a machine is accessing a computer(host/server) from your machine(client as if it is in front of you.The host might be located anywhere,yet it can accessed completely without physically touching it.

Remotely connecting to a machine is not a difficult task, and is found useful by many.It finds uses in distant troubleshooting i.e. companies like Dell,HCL are consistently using this technique to solve minor problems in computers. People
use remote connection to connect to their office PC's from their homes. In short it is a very important technique that one must know.

Remote connection can be established using graphical utilities or command line.
The number of utilities is enormous.For every OS, one can find a great number of utilities following various protocols.One must always remember that to establish a connection one must always use a software following the same protocol(set of rules) on both sides.

What exactly happens when using graphical utilities-The copy of the image received from host's display screen is displayed on the screen of the client.This copy is updated on a timed interval, or whenever the screen changes.The keyboard and mouse of the client are transmitted to the host and implemented. The host behaves as if the actions were performed directly at that computer.

In many cases the local display and input devices can be disabled to prevent interference,else the user at the host side may not let the client control the host.

Now,these softwares follow various protocols,the main ones being-
1)Remote Desktop Protocol (RDP) for Windows-
It is a proprietary protocol developed by Microsoft and clients exist for most versions of Microsoft Windows Linux, Mac OS X and other OS.By default the server listens on TCP port 3389

2)Remote Frame Buffer Protocol (RFB) a frame buffer level protocol-
It works at the frame buffer level and so is applicable to all windowing systems and applications, Windows and Mac.RFB is the protocol used in Virtual Network Computing (VNC).By default use TCP port 5900 or 5800 for browser access. A server can

3)Apple Remote Desktop Protocol (ARD) for Mac OS X machines-
It basically uses the RFB protocol only,but is known to cater to a utility that is user-friendly.

The important things that one must remember is that RDP/RFB (on port 3389 and 5900 respectively) should be allowed.The router needs to be configured to forward port 3389/5900 on the computer in consideration.The computer being connected to must not hibernate or stand-by or sleep. It must be powered on during the session.And finally the computers must be connected to the internet.

The only small challenge that one may face is the IP address of the host,when the host is not a part of the local network.Generally computers have Dynamic IP addresses that is it keeps changing every time a computer is switched off.
Also on the internet what is identified is only the router and within the local network it is the router which assigns IP addresses that keep changing.So either one can buy a static IP for a PC or one may leave his computer on all the time,which is not practical. Therefore,there are softwares like Teamviewer that remove the need of the IP address on the user front.
To know more about it one may use the following URL:-
http://www.teamviewer.com/download/index.aspx

In command line access one may use ssh(secure shell) or telnet in OS's providing a terminal. If one wants to establish command line connection in windows,then one needs softwares like Putty,that provide a terminal for Windows.

In computers nothing is difficult and the same applies to remote connection to a machine.