The End of a Micro Blogging Service

Of all the offerings, one of the first micro-blogging services to fall was Pownce (www.pownce.com). Pownce was started by Kevin Rose, the co-owner and founder of Digg.com. It started in January of 2008 and was shut down in December of 2008, just days after being taken over by Six Apart, the previous owner of the famous blogging site Live Journal. Pownce had a superior set of features as compared to some of the others.

The service could be availed via an invitation-based system. It was so famous that invites were even sold on online auctioning sites such as eBay. Some of the features that Pownce had were the ability to send messages, files, links and even set events. Files of up to 10 MB could be attached. The pro version of the service allowed even larger files. Groups out of friends could be made and sending messages to these groups was possible.

This was something not seen on most services and still isn’t very common. Pownce was talked about because of Digg’s huge community. It had support for mobile phones and there were clients based on Adobe’s AIR developed for it. The developers said that they would come back with something much better in 2009.

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Find Your Software Usage Pattern : Wakoopa.com

As if displaying your current status and presence weren’t enough; here’s a service that was designed to display what software users were using. The service is Wakoopa and its been around for two years now. It’s simple to use. After a registration, a small tracking program has to be downloaded and installed. This tracking application is available for Windows, Linux and Mac OS X. This application sends back statistics on the software being used and how often you use them. This data is displayed on your profile page at Wakoopa.com.

Wakoopa allows you to find similar users and in turn find better and newer software that you might have not come across. Wakoopa makes a chart of the software that you use and also creates tags according to the tasks performed by these programs. You can even click on a particular tag — chat for example, and get a list of programs for chat. There’s even small signature images that you can put up on your favorite social networking site that displays your most used programs.

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Cybercafe Security

You never know what kind of malicious program or person is lurking in the next public computer you are going to use

Cybercafes are not the safest place to surf. A number of users are bound to fill up the system with a whole bunch of viruses, worms and trojans, all of which can find their way into your portable devices. Some malicious programs can be used to relay personal information over the web. There may be keyloggers waiting to get into your accounts. Voyeuristic tendencies are not the only thing driving people to get access to your accounts, your e-mail account is one step away from your bank details and possible credit card numbers. Downloaded data, or data used for attachments can be abused by other people who come across it. A simple example: say user A downloads and prints a class project, and leaves the file there, user B comes along, and prints out the same project. There are a number of methods for gaining information, and using it maliciously. The techniques are many and varied, often changing from case to case. There are however, a few simple measures that users can take to ensure that they are not compromised while surfing at a cybercafé.

To start with, choose a cybercafé which is frequented by a lot of people. This ensures that there is a blizzard of data running through the computers, making your particular information less susceptible. Also choose a cybercafé which has enclosed cubicles. Make sure that your screen is not visible to passers-by, and your keyboard is shielded from anyone looking over your shoulder. This gives you privacy. Also ensure that the cybercafé allows you to use USB drives. It is OK if USB drive has to be connected to a computer that the administrator of the café uses, which is a common constraint. This allows you to bring along your own set of tools to keep yourself safe.

The first step is to prepare a USB drive. Set up a few useful portable software in one of these, and you are ready to tackle most of the security issues that people face at cybercafés. A portable version of Mozilla Firefox is the most stable portable browser around. There are portable builds of Opera too, if you prefer. Portable Firefox allows you to take your bookmarks and passwords with you, while not writing any information on the host computer. This allows you to bypass keyloggers as well. KeyPass is an Open Source application that stores all your passwords and allows you to login automatically. There is a portable version of KeyPass as well, which can be used in addition to portable Firefox.

Process Explorer is a small utility for monitoring system processes. It works off an exe file, without any installation. Process Explorer is a useful little tool to monitor, halt or pause any undesirable background activities on the host computer. It is also a good idea to carry a copy of Free Commander. Free Commander is a file explorer, that allows you to perform complex tasks and navigate the computer better. There is more on why this explorer is necessary later. Eraser is a great tool for deleting data securely. All these programs run directly from the USB drive, and don’t need administrator privileges. This set of applications can be used to avoid pitfalls, each of which are addressed individually.
Bypassing keyloggers

A keylogger can be any kind of mechanism to take a note of every key pressed by the user. There are a variety of keyloggers available, some of them are even open source! Keyloggers can be software-based, hardware-based, or both. A program that logs keystrokes is the most common kind of keylogger. Software based keyloggers can be remotely activated on a computer by a Trojan. This is usually accompanied by a time stamp. The keylogger does not itself know what is sensitive information and what is not. A typical log will look something like:

9:04 http://www.google.comuser@gmail.compass
9:05 word1hello,Iwasintownandwonderingif

Anyone going through the logsheet, can however sieve out the useful information. In this case, the username follows the url, and the password follows the username. Hardware based keyloggers, use a small chip in the keyboard, which is impossible to bypass. More sophisticated keyloggers can take periodic screenshots of the screen, track the mouse movements, log the keys and send all this information in real-time to a remote server. Some programs allow remote viewing of all activity on the host computer in real time. If you leave your computer unattended, they can even remotely control the mouse, and navigate to unsafe areas of say, your inbox. However, it is highly unlikely that anyone would go through the trouble to track the web activities of everyone in a cybercafé, because of the bandwidth involved. Sorting through all the data for anything useful is also a problem, but those with malicious intents have known to take the trouble. You should however, be mindful of specific and targeted attacks, where the probability of gaining sensitive information is higher. A cybercafé located in a business hub for example, is a very good target for such attacks.

Credit card details cannot be changed after a stint at a Cybercafe, and is something that should never be keyed in on a public computer. If it is absolutely essential, a simple precaution is to use an on screen keyboard. Go to the Start > Accessories > Accessibility > On-Screen Keyboard on any Windows system. A virtual keyboard will show up on the screen, and you can use the mouse to key in any sensitive information. Many banks offer virtual keyboards as part of their websites, use these for security when available.

A virtual keyboard is just an accessibility tool, and the default virtual keyboard can bypass only hardware keyloggers. If you frequent cybercafés, and are an advanced user of on-screen keyboards, there is a software called on-screen keyboard portable that can be used across machines. You can customize the keyboard, and take the settings with you. Users, can for example, set hover preferences that keys in the text without resorting to mouse clicks.

Keypass password safe

Not all software keyloggers can be bypassed with the use of virtual keyboards, as the keyloggers log the keypresses from the virtual keyboards as well. Some keyloggers are even configured to log only details from on-screen keyboards, which makes the work for the malicious person much easier, as the un-sensitive keypresses from the keyboard are not logged at all. The safest way to bypass this, is to use a process called obfuscation. Obfuscation basically allows keyloggers to log a certain combination of keys, while keying in a different combination. There are some programs that are targeted at different obfuscation algorithms, and bypass them, but this still remains the most secure approach to keying in sensitive details. The user does not have to enter the keys manually, or use a virtual keyboard in this process. The password, login details, and other sensitive information is stored in a secure computer, then the program is run on a public machine. At this point, the program automatically enters the details, while obfuscating the characters used.

The best software for this is an open source program called KeyPass. Open source software can be trusted in matters of security at least, since a lot of people stand to lose their data, the code is open for everyone to examine. That does not mean that the software is easy to bypass, quite the opposite, the open scrutiny gives more credence to the software.

KeyPass is a password “safe”, that stores all your passwords and sensitive information in one encrypted database file. This database file cannot be easily accessed, and can be taken around with you on a USB drive. You need just one password to access the database. To keep matters simple, people tend to use the same password across all the websites they access. If one account is compromised, all of them are. The best way to keep all your accounts secure is to keep different passwords for them, and change the passwords regularly. People who do this have a code or a system, where that they use to choose and cycle the passwords for different sites. Despite that, it is a good idea to use a password safe to store all your passwords. This way, you have to remember just one strong password, and you don’t have to key in your passwords on any site.

KeyPass works by using a sensitive information database. There are some steps that KeyPass takes to protect this database from intrusion. When you first run the software, you will be asked to create a master key and a keyfile. The keyfile is a file with random data, that is many times more secure than a password. A password more than 16 characters long for example, becomes very difficult to remember. Therefore, crackers or brute force methods, that exhaust all the possible combinations can get into the information with relative ease. In practice, this takes a long time, but is not impossible. A keyfile makes intrusion much more difficult, and beyond the purview of current brute-force intrusion methods. First you will have to create a master password for the database. The longer the password, the stronger it is. The more numbers and special characters you use, the better the password. KeyPass gives you an indication of how strong your password is. Anything over 50 bits in the “estimated quality” field is good to go.

You can choose to opt out of creating the keyfile. However, if you are storing a lot of sensitive data in the database, it is a good idea to create a keyfile. Click on Create to make a keyfile. There are two approaches to make a keyfile. Both these approaches ensure that the keyfile is truly random, and not pseudo-random. On the left is a field of noise, which the user has to run over with a mouse. Alternatively, a user can choose to key in random data from the keyboard. The more secure approach is to run the mouse randomly over the noise field, as even a random set of keys from a human user concentrates on a few keys, and is not that random.

You can stop once 256 characters are reached, which is many times more secure than a 12 character password. Now the database should have a few default fields. Fill this in and add details as necessary. For all the frequently used entries, you need to enable auto-type. Auto-type automatically fills in the username and passwords in a number of sites. Auto-type works for most kinds of windows, but not all. Any field in a standard web page is accessible, and all the browsers are supported. There are a few places where auto-type does not work, such as a command line interface. Unless you are using a text-based browser, this should not be a problem.

When you edit the preferences for an entry, go to the Auto-type tab, and check Enable auto-type for this entry. Also check two-channel auto-type obfuscation. This is the feature that makes the text invisible to any kind of program that discovers cloaked text, or software keyloggers. You will be warned that auto-type obfuscation will not work everywhere, but ignore this warning as it is applicable to only the command-line type scenarios.

Carry your browser with you

Portable Firefox, and Opera@USB are both browsers that you can take with you to cybercafés. A simple way to bypass the process of entering e-mail information is to select the “remember me” option on a secure computer. The browser does not save any data on the host system, and all the necessary files are stored on the portable memory. Since the programs are already installed, you don’t need administrative privileges to run the software. Additionally, this will save you a lot of time, as your favorites and bookmarks are carried with you in the browser. To use either of these browsers, just use the installer and install the browser in the relevant USB drive.

Securely deleting data

Ideally, you should be using public computers like a ghost. No trace of your activities on the computer should be left behind. If you have downloaded any kind of data, or have created data in the cybercafé, it is a good idea to delete the data before you leave. Even if you use [Shift] + [Delete] to get rid of the data, or empty the Recycle Bin, the data is still there on the hard drives, but not indexed in the filesystem. This means that fairly simple and commonly available file recovery software can be used to recover the deleted data. There are a number of free and portable programs to securely delete data from the hard drive. These programs manage to do this by overwriting the empty space, or the areas of the hard disk occupied by the file. We will be using two programs for securely deleting data – Free Commander and Eraser. Free Commander is faster, less secure, but should do for most day to day purposes. Eraser is a highly-specialized application, and can offer as much security as time permits.

Free Commander is a free file browser that makes exploring the file system easier. Folders show up with sizes, and there is a dual-pane interface that makes moving data around a breeze. To securely delete data, select the files or folders, then go to File > Wipe.

Free Commander offers up to ten overwrite runs. Each “run” involves rewriting the area where the data was stored with random data. The more the runs, the more irrecoverable the data becomes. However, if you have deleted data, without wiping it, then it can be recoverable by a file recovery software. Free Commander has no function to erase the empty hard disk space, and rewrite the empty information. This is where Eraser steps in.

Eraser is a deceptively simple looking program. Go to File and add tasks to add the parts of the hard disk that has to be erased. The user can add empty hard disk space, specific folders, or individual files. Each operation is called a task, and any number of tasks can be added to a list known as the task list. Eraser goes through the task list, erasing the identified data one at a time. At each instance of an erasing operation, there are a whole range of secure deletion options available to the user. There are a few default patterns in which the erasing occurs, but this can be entirely tweaked by the user. The most secure default pattern offered by the program is the Gatmunn method, which involves thirty five passes. This is more than anyone really requires. Click on new to create your own pattern. You can specify an unlimited number of passes, and define what kind of data is used to overwrite the file or empty space in each of these passes. A pattern overwrite uses a specified pattern, and the pseudorandom data overwrites with random characters. We specified an operation which implements 101 passes. Note here, that the more passes you specify, the more is the time taken. Overwriting files and folders is a relatively fast operation, compared to rewriting all the empty space in a hard disk. Even a 10 passes operation will take a long time when it comes to clearing hard disks with a lot of empty space. Also note that two or more identical passes, following the same pattern (say all zeroes) is the same as one pass with that pattern. Either alternate the pattern, or sandwich patterns between two pseudorandom data passes.

Protect your USB drive from viruses

The first thing to do when you plug in your USB drive into a public computer is to identify and disable malicious processes running on the host computer. A great utility for doing thing is Process Explorer. Process Explorer is a free alternative to Windows Task Manager. Process Explorer can halt or disable undesirable processes. The most useful little feature in Process Explorer is, if there is a process that restarts when you stop it, you can suspend in and leave it hanging while you continue with your work.

Some experience with the process manager is required before you can identify the harmful or irregular processes right away. The website ProcessLibarary.com lists all the harmful processes, and has a listing of the most common threats. If there is a process you are suspicious about, this is the place to identify it. Process Library also has lists of legitimate processes, so you know at any point of time everything that is going on in your computer.

If you want to use more active measures, Clamwin is a free anti virus software that is also portable. As with all anti virus software, the anti virus definitions have to be updated regularly. This can be done when you run the anti-virus from the cybercafé itself. The first time you update the definitions, the process is going to be quite lengthy, as the installer of the anti-virus does not come with definitions. The updates are much faster after the first run.

Scanning for viruses, worms and Trojans takes some time. Not only can you prevent viruses from infecting your USB drive, you can also scan and fix the host computer from an installation in your drive.

These software should help you stay secure in most situations, and all of them are in the accompanying DVD. However, attackers are likely to target the humans as much as the computers. Don’t give away banking details to anonymous people, no matter who left you property in their wills, or which lottery you won. Don’t follow links to banking sites through e-mails, as they may be dummy sites that are made to look like the official sites. Use the URL of the official sites that you trust, and have used before.

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Why Zapak is Best Gaming Site ?

Casual gaming has turned a new page in India, where games are not only restricted to kids. Now people of all ages are going online to play games – maybe not everybody plays games such as Counter Strike, but something more relaxed and just for fun. Game portals have also been created to support specific audiences such as women, with games related to clothes and children, and others revolving around educational puzzles. Certainly, there are some evils associated with gaming such as being too addictive and time-wasting, but if computer games are played in a more controlled environment, then they can even prove beneficial. There have been studies that show how games have improved the overall concentration levels of individuals, for example.

In this category, we have taken into consideration only those sites that offer browser-based games. There were a few sites such as Indiagames.com, quite popular with gamers, but do not provide instant gaming action, needing a client to be downloaded, so these did not make the cut.

The sites that made our short-list for this category are Indiaarcade.com, Games2Win.com and Zapak.com.

The features that we first looked for were the sheer game content and how easy it was to just start playing. None of the sites gave us any problem with starting a game quickly. Then we also looked for how the games were categorized on the site and how easy it was to navigate, and find something of interest. Additional features such as loyalty programs, competitions and rewards received a big thumbs up from us. By now, you must be wondering who the winner is; so let’s not keep you guys waiting any longer – Zapak.com wins this round.

Zapak.com does not have all the features a game web site could have, but it makes up for this with other features that keep drawing people towards it. It has a very good category system and a search option that also works accurately. Zapak.com could be considered the main site, but it has other gaming sites which cater for specific audiences, such as girls.zapak.com, cricket.zapak.com, world.zapak.com. All these are listed clearly on the left side of the page. Another good thing about Zapak.com is that it frequently hold contests and tournaments where users can win loads of prizes, including cash prizes.

Currently, it is hosting its ATM2 contest, where all you have to do is play games to win prizes.

Other than the list of multiplayer games, Zapak.com also offers browser-based MMOGs (massively multiplayer online games); these include Wanted and Power Soccer. The community features present on Zapak.com were not seen with the other sites. Once you register, you can add friends, send messages and chat with other gamers. One thing missing from Zapak.com is that no game description is given when you view a list from a category; only the name of the game and a thumbnail image are displayed. Another problem, we feel, is that a complete newcomer might get lost and not know what to do at Zapak.com as there are too many options, but we can’t say that this is really such a bad thing.

Indiaarcade.com, one of our runners-up, has a huge collections of games, though the whole multi-player element is missing. It deserves a mention because anybody and everybody can just go to the site and start playing a game with ease – we found it the simplest, as the layout is very pleasant and straightforward. Also, the games had small descriptions along with thumbnails so people can get a better idea of what they are about to play.

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Mobile WiMAX : Meet 802.16e

We are about to experience yet another revolution. Worldwide interoperability for microwave access (WiMAX) has the potential to do to the internet exactly what mobiles did to telephones.

The world was revolutionized with the advent of mobile phones. Along came the concepts of text messaging and missed calls. These ensured we always stayed connected to our contacts.

We are about to experience yet another revolution. Worldwide interoperability for microwave access (WiMAX) has the potential to do to the internet exactly what mobiles did to telephones - to make it wireless on the large scale. Additionally, it can also be used to help mobile telecommunications.

What was wrong with WiFi?

A popular misconception is that WiMAX is aimed at replacing WiFi. This isn’t entirely true. WiFi is only concerned with creating a wireless pocket of connectivity around the router, instead of being strangled with a wire.

WiMAX, on the other hand, takes wireless to the maximum (although that isn’t what it stands for), by facilitating wireless broadband connectivity of up to 3 Mbps spread over large areas. WiFi can be used to create wireless local area networks and provide internet connectivity to computers in the range of a router however it doesn’t provide a viable means to connect computers over a wide range, say that of a city. WiFi can thus be thought of as a wireless alternative to Ethernet networks, while WiMAX is an alternative to technologies such as DSL.

WiMAX

WiMAX is an acronym for Worldwide Interoperability for Microwave Access. It is a relatively new technology, having been first introduced in 2004 as 802.16, more popularly known now as ’fixed WiMAX’. It was created as a technology to provide the last-mile connectivity for broadband access. This means that it can potentially be used as a replacement for current broadband network systems such as DSL, landline or cable connectivity.

Where WiMAX wins out here is due to the fact that it is wireless, and as such huge savings can be expected from implementing this is place of wired technologies. Just like cellular-phone towers, setting up one WiMAX tower has the potential to cover a large area, and as such, can also be used to provide connectivity to some of the more remote areas where wired connectivity is currently unavailable, infeasible or expensive.

In a revision accepted in 2005 named 802.16e, many improvements were made to the standard, some of which were to enable the use of WiMAX in mobile installations.

IEEE 802.16e-2005

This is indeed the full standard name for “Mobile WiMAX”. This amendment of the WiMAX standard is perhaps most popular for the addition of features enabling its use in mobile installations. The standard describes itself as “Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands”, changing the title of the 802.16 standard to “Air Interface for Fixed and Mobile Broadband Wireless Access Systems”. WiMAX, by itself, promises wonders, then why all the hype about this new amendment?

Consider this – you have full speed broadband access on the go; surfing wirelessly at home, you could check your email on the way to work, and continue working once there without ever needing to connect a wire! What if this connectivity existed everywhere, you would never have to worry about searching for hotspots. The whole city would be a hotspot. But then, since this is India, you’ll have to imagine waiting for another three decades before this becomes a reality.

One of the key technologies for facilitating mobile access of WiMAX networks is a scheme called SOFDMA (Scalable Orthogonal Frequency Division Multiple Access) which is a scalable form of the system used in 802.16-2004 OFDMA (Orthogonal Frequency Division Multiple Access).

SOFDMA Deconstructed

Scalable Orthogonal Frequency Division Multiple Access, quite a mouthful! However if we break it down into its components it begins to sound much more sensible.

Scalable: Scalability is important when considering any technology. Especially for WiMAX which can be used to provide connectivity for as far as 50 miles, and maybe used for bandwidths up to 70Mbps by a large number of people simultaneously.

Orthogonal: This means mutually perpendicular. Here it applies to signals, that the signals are perpendicular to each other so that when one is at its peak, all others are zero.

Frequency Division: This is a means of transmitting multiple signals via a single medium, by using carriers of different frequencies. DSL is an example of how voice signals and internet connectivity signals are both carried in the same line.

Multiple access: This bit is obvious, a single access internet connection would be amazing surely, but the waiting in line for access would be quite annoying! Networking technologies have to ensure a feasible and stable method for allowing multiple people at access the service at the same time.

SOFDMA builds upon OFDMA which builds upon FDMA. SOFDMA is thus a specialized form of frequency division multiple access (FDMA). However, it is incompatible with the earlier technologies in some ways, and will require WiMAX ‘broadcasters’ to upgrade their equipments to support SOFDMA.

So, why SOFDMA, what does it do, and why is it important, that it was introduced despite compatibility issues.

Bandwidth, frequencies and data transfer

To transmit any kind of data it needs to first be modulated so that it can be carried over some kind of medium. Wired methods transmit data by sending electric signals of varying frequencies through the wire, which are modulated with the information to be sent. This modulation process involves the conversion of data which is composed of binary digits into a kind of electrical waveform.

In the modulation process, a base waveform or a carrier wave, is taken and modified with a pattern which is representative of the data being transferred. What quality of the carrier wave is modified depends on the modulation used. How much information a wave can carry depends greatly on the frequency of the waveform.

Different modulation schemes approach modulation in different ways in order to gain better and better efficiency. It is better to divide the same data and send it in parallel at multiple lower frequency bands than to transmit it over a single very high frequency band. The reason for this is simple, a single channel carrying data at 1 Mbps means that each binary digit will occur for just 1 micro-second! On the other hand, sending the same over 100 channels at 10 kbps would give us a much better duration per bit leading to easier detection.

The reason FDMA is superseded by OFDMA and OFDMA by SOFDMA is precisely because each improving technology brings with it better bandwidth efficiency, greater reach and better stability. The main concept used in all technologies remains frequency division, so let’s have a look at FDMA from which they evolved.

FDMA

FDM or frequency division multiplexing is a way of transmitting multiple streams of data along the same medium (wired or wireless) by using different frequency bands for each channel. By keeping the frequency bands far enough apart, we can ensure that each channel can be filtered out separately. We can compare this to a room filled with people speaking in different languages. Although you may be able to hear everything, you will only be able to understand the languages you know.

In reality, we can look at the example of an FM Radio, where different channels come at different frequencies. One signal may be allotted a central frequency of 98.1 MHz with a bandwidth of 200 kHz, meaning that it will broadcast at frequencies between 98.0 MHz and 98.2 MHz, while another may be allocated a 200 kHz bandwidth around the 98.7 MHz. As such, each frequency band is separated by sufficient margins so that they don’t overlap or interfere. On the receiving end, we can tune in the receiver to a particular frequency and filtering out the other signals, and boosting power at the selected frequency.

FDMA (Frequency Division Multiple Access), works by giving different users their own frequency bands, thus each user can communicate using a channel of their own.

This makes FDM quite inefficient, as a lot of bandwidth is wasted in the gaps used to separate different frequency bands. OFDM or Orthogonal Frequency Division Multiplexing packs in much more information by eliminating the requirement for these gap-bands.

OFDM and OFDMA

With OFDM (Orthogonal Frequency Division Multiplexing), sub-carriers in the signal wave can be overlapping without causing any interference. This is accomplished by making the sub-carriers in an OFDM exactly orthogonal to each other, meaning that while one is at its peak the others are all zero. The efficiency is greatly increased by this, as more data streams can now be transmitted using the same bandwidth.

OFDM spreads out the data among multiple carriers, each of which is modulated separately. As there is now larger number of carriers to modulate, the effective system throughput is increased. Also since a large no of frequencies is used, some of the issues surrounding wireless communication such as multi-path, signal cancellation, and spectral interference are reduced to a great extent.

However in OFDM each channel is assigned to a single user. To enable multiple user access it is additionally used with Time Division Multiple Access (TDMA) or Frequency Division Multiple Access (FDMA), however each approach has its caveats.

OFDMA (Orthogonal Frequency Division Multiple Access) as its name suggests is designed for multiple user access. Unlike OFDM, OFDMA is capable of supporting multiple users on the same channel, by dividing each channel into sub-channel groups. Insofar that the channel assigned to any user will be optimized based on which will perform best for the current user’s location, environment and equipment.

In the original 802.16-2004 specification, OFDM-256 was used, which meant each channel would be composed of 256 sub-carriers and multiple user access available via TDMA (or FDMA). The 802.16e-2005 spec adds OFDMA 128/512/1024/2048, while the old OFDM-256 is kept for compatibility reasons.

What a difference an alphabet can make!

SOFDMA

SOFDMA is OFDMA but with scalability to enable its usage in a wider variety of scenarios, especially mobile. While the original 802.16-2004 standard was meant to enable wireless internet access to fixed locations such as homes and businesses, where a WiMAX receiver would be affixed outside a the building similar to a dish antenna, in 802.16e-2005 many specifications were added which would enable a mobile system to access the network.

SOFDMA is scalable in that it allows for changing the bandwidth allocation to channels from 1.25 MHz to 20 MHz. Smaller channels such as those to be used by mobile devices are optimized for lesser system complexity, while higher bandwidth channels such as those used by fixed point subscribers at home or in offices, are optimized for higher bandwidth. Even the modulation scheme is scalable such that a different encoding scheme can be depending on the quality of the signal.

Other 802.16e features

Many other features were also added in 802.16e-2005, to improve its mobility characteristics, an important one being MIMO (multiple-in multiple-out). Other than the mobility enhancements, there were also the addition of HARQ (Hybrid Automatic Repeat Request), and QoS (Quality of Service) improvements.

MIMO

To improve the range and speed characteristics, multiple antennae can be used at the transmitting and receiving station. This improves the maximum range of the transmission and the data throughput. Using this in WiMAX means that without increasing the output power of the transmitter, and while keeping the same bandwidth, they will be able to provide better performance to a longer range. This is of obvious benefit in mobile access, as it enables customers to get better access with wider area coverage, all without significant cost increase to the broadcaster.

QoS

Networks are used for a wide variety of communication, from internet gaming to bank transactions, each type of communication requiring different network characteristics. While we may consider out internet surfing quite important, there are many other protocols which are less resilient to network outages or interruptions. VoIP for example requires a constant guaranteed minimum rate of data flow for communication to persist. To guarantee that such time and delay critical communications are not interrupted, QoS protocols are employed to give them higher priority. Communications of different classes are given different priority. The QoS in 802.16e-2005 divides network communication into 5 classes:

1. Unsolicited Grant Service
2. Extended Real-time Polling Service
3. Real-time Polling Service
4. Non-real-time Polling Service
5. Best Effort

VoIP falls in the second class, and our favorite HTTP communication is sadly last, given only as much bandwidth as is left over in the end.

WiMax vs LtE

There is another war of standards coming up! LTE stands for Long Term Evolution, and it widely thought of as an upgrade path from the current GSM 3G / 3.5G standards. It has backing from a majority of the GSM providers, but unlike WiMAX it is not based on an open standard. Although LTE cannot compete with WiMAX in all its facilitations, in the mobile sphere they are both quite well matched. In fact they both use the same OFDM and MIMO technologies for communication. LTE has the upper hand in speeds right now, with the soon to come 802.16m standard, WiMAX may well overtake LTE. Unlike LTE for WiMAX mobile access is already available, and already starting to get implemented. As LTE cannot compete with WiMAX in all fronts, it is unlikely that LTE will replace WiMAX, but as far as the mobile space is concerned, the battle is ON!

Conclusion

Are we ready for internet as easily available as telephone signals? I believe we are, we have been good, and we deserve our candy. WiMAX is not the technology of the future; it is already something that is being implemented in many areas around the globe, a good example being WiBRO, which is an 802.16 implementation in South Korea.

802.16 holds a lot of promise for more than just internet, it is potentially a technology that can provide a wireless backbone for the telecommunications industry. Our homes are already starting to get wireless, WiMAX aims to make entire cities wireless, which if you live in India you can clearly sympathize with.

No more broken connection due to wiring faults, or overloaded trucks passing through narrow streets! Just like mobile phones have made the telecommunication an indispensible tool, and taken us from one landline per home to one phone per person, so does WiMAX hold the potential to someday make internet as personal and as available.

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