Wi-Fi Technology Detailed Information

This technology is widely used by many devices in different places. This is the most commonly used type of wireless technology to connect and share data between devices, in homes and businesses. This technology is commonly found in Computers, Laptops, Wireless Routers, Mobiles and other devices.

Difference between IEEE standards

There are different standards of Wi-Fi. Firstly there was the 802.11 legacy, which was released back in 1997, it operated in the 2.4GHz band and it had a maximal data rate of 2Mbit/s, the distance varied from 20 to 100 meters. Then there was the 802.11a, released in 1999, it operated in the 5GHz band and it had a maximal data rate of 54Mbit/s and it covered a distance of between 35 to 120 meters. Maybe a more known protocol the 802.11b, released in 1999 which operated in the 2.4GHz band and had a maximal data rate of 11Mbit/s and it varied from 38 to 140 meters of coverage. Now, the most used of all, the 802.11g released in 2003 with a coverage distance between 38 to 140 meters and with a maximal data rate of 54Mbit/s, although there are some routers that use this protocol and can have a data rate of 108Mbit/s, this is known as Super G, this uses two 802.11g 54Mbit/s channels therefore it doubles the data rate (54Mbit/s x 2). The most recent one is 802.11n but this is still under development, still in version Draft 4.0 but it operates on 2.4ghz and 5Ghz, it has a maximal data rate of 248Mbit/s and the coverage distance varies from 70 to 250 meters.

Besides all this, there is another protocol that is predicted to be released in the near future.
The Wi-Fi Compared to other transmission media

Bluetooth
Bluetooth is usually used in mobile phones and laptops, because it's cheap and quite fast for small files. It has a maximal distance of 100 meters, depending on the Class and a maximal data rate of 3 Mbit/s, which is very slow and and doesn't cover much distance compared to the modern Wi-Fi standards. Besides that, the Bluetooth signal becomes very weak when there are obstacles, while the Wi-Fi signal remains quite strong from one room to another and wall after wall.

Infrared (IrDA)
Usually this is found in older phones and laptops and it's very slow, although new and improved IrDA devices can transfer up to 4Mbit/s, while Wi-Fi, depending on the protocol, is much more faster, but the range is still a problem, usually it can cover only 1 meter and there should be no obstacles between the devices, they should be able to 'see' each other, or otherwise the connection will be lost, while on Wi-Fi the signal is quite strong, even with several obstacles.

Fiber-optic
This is a high speed connection, way faster than Wi-Fi, the date transmitted is hard to get corrupted, while Wi-Fi can easily be corrupted because if another wireless devise is using that frequency they will clash. The Fiber-Optic cable can reach up to 2Km easily, while Wi-Fi covers only a couple of meters, maximum 250m, but then, Fiber-Optic is very, very expensive. But then with Wi-Fi you can move easily around, because it overcomes many obstacles around the house and its wireless... while Fiber-Optic can only bend to a certain extent, and being a cable, you don't have the ease of move.

Hardware units required to build a Wi-Fi Environment

To create a Wi-Fi environment all you need is a wireless router, nowadays routers for home use are quite cheap and they contain all the security needed for a normal home or small shop network. Then you need a USB Wi-Fi dongle, or any other wireless network adapter, usually these are built-in devices that come with laptops, and if you want to share internet you will need the modem of the internet to be connected to the WAN (Wide Area Network) port of the router. As soon as everything is switched on you will have a Wi-Fi environment and then just use your desktops with the USB dongle or your wireless enabled laptop and connect to your network. But you might want to configure your router for additional security from the Administration Panel.

Building the most cost effective network using Wi-Fi
In this case you need two wireless devices that support Wi-Fi. The most cost effective way of connecting two devices together is via an ad-hoc (peer-to-peer) connection. You can simple create such a network, these are the steps:

1.Open the Network and sharing Center
2.Select 'Setup a Connection or a Network'
3.Choose the ad-hoc type
4.Press next on the next dialog
5.In the next dialog choose a network name, security type and a passkey
6.The network will be created
7.Press close on the next dialog
8.The network is ready
9.Go to the other computer, find the network and connect to it. You can now share files etc...

Security Issues

Accessing The Administration Panel
Well, if you fail to set security features on your router anyone can access and connect to your network, and if you are sharing some folders, if you fail to set privileges, anyone can view, copy, edit and delete your files without you even noticing this! Besides that if your router is sharing internet then they can easily have internet access for free and consume your download bandwidth that you pay for. So unless you want this from happening you should set up some security features, like a passkey and encrypting the connection, this should get you started.

The first thing to do is to access your router's administration panel, to achieve this usually you have to open a browser and type in the IP of the router, you can achieve the IP in three ways. You can either try out 192.168.1.1 this is usually the default IP of the router. If that does not work you can go to the classical way, consult your manual or the last method, it might sound complicated but it's another way. So open the command prompt, usually known as CMD
Now that you are in the command prompt just write 'ipconfig' and there you should see the connections that are configured on your computer, find the one either marked as Local Area Network or Wireless Network Connection, and under that you will see some IP's, subnet mask and the default gateway. Now, the default gateway IP is the IP of your router, or at least it should be. Now open your internet browser and in the address bar write the Default Gateway IP

Then you are asked for a username or password, insert both, usually default values are admin and admin. But for that you might want to consult your manual.

Encrypting the Connection
Now that you are in the admin panel go to the wireless section and you should be able to see a security option which will let you choose the encryption type and the passkey.

Types of Encryption
The two most 'famous' and known types of encryptions are the following.
WEP
This was an early attempt to encrypt data over Wi-Fi, this is easy to configure, but easy to crack too. It supports up to 128-bit encryption but in spite this, I saw videos on youtube that cracked this type of encryption in a couple of minutes with a normal PC computing the decryption. If you
WPA
This is a more secure, encryption to protect your data over Wi-Fi. This protocol was created to overcome some weaknesses on the WEP protocol. This type of security is harder to crack, but you can crack it with a normal PC, using some special software.

MAC Filtering
For additional protection you might want to block all MAC addresses except the ones of your computers . Most routers have this function, they read the MAC address of your network card and if that MAC address is not in the allow list, they will not let that computer to connect to the network.

It's never secure enough!
Still you are not 100% protected, because, these encrypted passkeys can be easily cracked via special software that are able to pickup certain packets of data being transmitted and they can even crack the passkey from these packets, and, even though you blocked all MAC addresses except your own ones you still are not 100% protected because there are special software that are able to spoof the Mac address of the network card and make it appear like your computer's MAC address. Besides that, to crack the Wi-Fi encryption and get the passkey, there is a dedicated Linux OS designed for cracking Wi-Fi, Bluetooth and tons of other things. It's called BackTrack, you just burn it on a CD and boot it, this makes the job very easy to crack. So you are never safe... not even in your own house, because someone might be cracking your Wi-Fi connection.

Bibliography
http://computer.howstuffworks.com/wireless-network.htm
http://en.wikipedia.org/wiki/Wi-Fi
http://en.wikipedia.org/wiki/IEEE_802.11
http://en.wikipedia.org/wiki/Wi-Fi_Protected_Access
http://en.wikipedia.org/wiki/Wired_Equivalent_Privacy