LifeOverflow

Until a few weeks ago, I was under the impression that 80.11n standard is currently in draft when a friend of mine pointed out that his MacBook supports 802.11n. This got me thinking over 802.11n and how can a device be available for supporting a standard that is not finalized. Upon researching, I found out that many companies, including apple, have launched devices supporting the latest draft of the 802.11n standard and hope to provide firmware upgrades when the final standard rolls out.

 The 802.11n standard is an amazing improvement over the currently used 802.11g standard. 802.11n standard supports link rate of 600 Mbps in comparison to the current 54Mbps supported by the 802.11g standard. It also incorporates the MAC enhancements for QoS and power savings as defined in the 802.11e standard. The increase in the link speed can be attributed to the folowing enhancements:

1. Increase in subcarriers
The OFDM subcarriers were increased from 48 in 802.11 to 52 in 802.11n boosting the throughput.

2. Decrease in Guard Interval
The guard interval is decreased from 800ns to 400 ns

3. 40Mhz Channels
The other 802.11 standards have a channel bandwidth of 20 Mhz. 802.11n has an optional mode, where the channel bandwidth is increased to 40Mhz. As the channel bandwidth is doubled, the number of data subcarriers is slightly more than doubled, going from 52 to 108.

Here are some of the sites that I would recommend for any information regarding CSS

The W3C writes the code we use.

• W3C Site Guide
• CSS1
• CSS1 errata
• CSS2
• CSS2 errata
• XHTML 1.0
• XHTML 1.0 errata

How To Read W3C Specs

SelectORacle translates CSS2 and CSS3

Mailing List

CSS-Discuss

Others to be mentioned

A List Apart

Evolt

Digital-Web

CodeBitch

WaSP

Validation

W3C Markup Validator

W3C Link Checker

W3C CSS Validator

W3C CSS Validator FAQ

Other tools

• Gazingus
• Tantek
• Malevolent Design

If you put up some photos of paintings or certificates or any personal stuff on the internet, at some point someone is going to use those photos without your permission. You may feel that your stuff is ’stolen’, but there isnt much that you can do in order to protect your images. So what do you do?

1. You can start by putting up low-resolution images on your website at a size as small as possible. A resolution of around 72 dpi would be fine for viewing on the web. These low quality resolution images may be copied for use on the web, but are no good for printing out.

2. Watermaking your pictures has been one of the favorite methods of discouraging others from using your images. You can easily put up a semi-transparent text across you image to deter the others from using the images directly. It is possible to remove a watermark, but most people wont spend the time doing so.

3. Some websites disable right click on their websites in the hope to stop their content from being ’stolen’. I would not suggest the scheme as it turns out to be highly irritating for the visitors and it is very easy to bypass. Anyone can disable scripts in his browser for your page and easily download the images from your website.

4. Another not-so-commomly-used method can be to incorporate each of your image as a separate Adobe flash object. However, initially you need to create different flash objects for each of your images. On the upside, no one can right-click-and-save your images nor can anyone download the images from the path. But there do exist softwares to specifically download flash objects from the website. Once downloaded, graphic objects can be easily extracted from the flash objects.

5. Some developers use the technique of image hiding. In this technique, the original image is placed as the background of a table cell introduced at the position of the image on the webpage. Above the background image (the image you need to display), you place a transparent image of the same size. When the visitor right-click-and-save the image, without knowing he selects the transparent image to be saved. The technique relies on the assumption that the visitor wont notice that he has saved the wrong image until much later and will decide that returning to your site to steal the right one is too much effort. The code for such a technique can be generated here.

6. The last one possibly the most complex and the most time consuming of all is the slicing method. In this method, you can use any software like Adobe Fireworks (my favorite!) for slicing the images into several parts. The same software is capable of generating the appropriate html code to re-assemble the image parts on the webpage. You can copy the generated html <table> code (without the <html> or <body> tags) into your webpage. In this case, with the visitor right-click-saves, he is able to save only the sliced part of the image where he clicked. In order to obtain the complete image, he has to download all parts and then re-assemble the parts like a jigsaw puzzle in his webpage or a photo editing software. This method may be used by applying this process to a low resolution image. Click here for a sample image

The slicing method is my favorite amongst all. However, the inital prep for all images has always been a big deterrant for adopting this method. I plan to code a script to automate the slicing procedure in the near future. Keep a check on this page for any updates.

Even with all the methods described above, the user can still use print-screen and obtain the image using a simple photo editing software. Thus, all the methods described here are still not capable for providing complete security for your image content on your webpage. However, a combination of the techniques described above can really discourage someone from downloading your images for personal use.

A mobile ad-hoc network (MANET) is a self-configuring network of mobile routers (and associated hosts) connected by wireless links—the union of which form an arbitrary topology. The routers are free to move randomly and organize themselves arbitrarily; thus, the network’s wireless topology may change rapidly and unpredictably. MANETs are usually set up in situations of emergency for temporary operations or simply if there are no resources to set up elaborate networks. These types of networks operate in the absence of any fixed infrastructure, which makes them easy to deploy, at the same time however, due to the absence of any fixed infrastructure, it becomes difficult to make use of the existing routing techniques for network services, and this poses a number of challenges in ensuring the security of the communication, something that is not easily done as many of the demands of network security conflict with the demands of mobile networks, mainly due to the nature of the mobile devices (e.g. low power consumption, low processing load).

Proactive vs Reactive Routing

Proactive Schemes

Determine the routes to various nodes in the network in advance, so that the route is already present whenever needed. Route Discovery overheads are large in such schemes as one has to discover all the routes. Consumes bandwidth to keep routes up-to-date Packet forwarding is faster as the route is already present. Examples of such schemes are the conventional routing schemes, Destination Sequenced Distance Vector (DSDV).

Reactive Schemes

Determine the route when needed .Smaller Route Discovery overheads. Employs flooding(global search) A node trying to transmit a packet may have to wait for route discovery. Examples of such schemes are Dynamic Source Routing, Ad-Hoc On Demand Distance Vector Routing (AODV) etc.

Flooding

Some routing protocols will find a apart form proactive and reactive there is another mechanism called Flooding. In flooding no route is computed or discovered. A packet is broadcasted to all the nodes in the network. Flooding is the easiest routing method, however it generates heavy traffic.

Different proactive, reactive and even hybrid (reactive as well as proactive) schemes e.g. Zone Routing Protocol, have been proposed for Wireless Ad-Hoc networks

Industries working in this domain

• AT&T Bell Laboratories
• Bell Communications Research, a.k.a. Bellcore
• BellSouth Enterprises
• Ericsson Radio Systems
• GTE
• Hughes Electronics Corporation
• ITT Industries
• Lucent Technologies
• MCI Telecommunications Corp.
• Motorola
• National Semiconductor
• Nokia
• Nortel
• Qualcomm Incorporated
• Radix Technologies
• Southwestern Bell
• Telecom Analysis Systems, Inc.
• Texas Instruments
• US West Advanced Technologies
• Watkins-Johnson

Academic Wireless Research Laboratories or Projects

Broadband and Wireless Networking Laboratory, Georgia Tech

Center for Wireless Communications, UC San Diego

Computer Systems Laboratory, UC San Diego

Institute for Systems Research, University of Maryland

Mobile Computing and Multimedia Laboratory, University of Maryland

Mobile Multimedia and High Speed Networking Laboratory, Georgia Tech

Monarch Project, Carnegie Mellon University

MONET Group, University of Illinois

Multimedia Wireless LAN Group, UMass

Networks and Mobile Systems Group, MIT

PLEIADES Project, Stanford University

WINLAB, Rutgers University

Wireless Communications Research Group, Stanford University

I was asked by a friend to find the whereabouts of a song “want you to know”. I didnt know anything much about the song other than you can listen to it www.thefreelancehellraiser.com. So I browsed through the site, and found their jukebox. I listened to the song and I liked it.. a lot.

My friend suggested that the song must have been downloaded into the temp files of internet explorer. At first i thought that the site admins must have taken that into account to stop illegal downloading from their own site. But I checked it and it was right there in my Temporary Internet Files folder. The admins had not managed to cover up the streamed audio. So, I am putting up here the step by step procedure to obtain the files from your temporary internet files directory.

To get that song, go to www.thefreelancehellraiser.com and listen to any of their song.

then Go to (windows installation partition)\Documents and Settings\(windows user account name)\Local Settings\Temporary Internet Files

sort the files by “Last Accessed” and near the end of that folder, you’ll find a file named track(a 2 digit tracknumber)

.mp3

the (tracknumber)

will be a two-digit number of the track from the playlist on www.thefreelancehellraiser.com

Simply copy the file from that folder and place it anywhere you like.

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I also found another way.. Its simpler.

To download any of their songs, just go to www.thefreelancehellraiser.com/jukebox/track(tracknumber)

.mp3 where track number is the number of the track from the playlist on their site.

NOTE: The track number is in 2 digits i.e. for the first song “want you to know”, use tracknumber as 01

For example, the link for the song “want you to know” is www.thefreelancehellraiser.com/jukebox/track01.mp3

Use a download manager, to save the above link onto your computer.
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NOTE: The above procedure should not be used for any illegal purpose. The user is himself/herself responsible for any way he/she uses the content on the site.