Sunday 2 October 2011

comparison of different wireless interface


COMPARISON OF DIFFERENT WIRELESS INTERFACE

Most wireless networks (WLANs) are currently based on IEEE 802.11 a/b/g/n. 802.11 family consists of a series of over-the-air modulation techniques that uses the same basic protocol. It is a set of standards for implementing wireless network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802.11). The table below compares the standards: 


802.11 interface
Frequency (GHz)
Speed (Mbps)
Bandwidth (MHz)
Allowable MIMO streams
Modulation
Approx. indoor range(m)
Approx. outdoor range
a
5 / 3.7
25-54
20
1
OFDM
35
120
b
2.4
5-11
20
1
DSSS
38
140
g
2.4
25-54
20
1
OFDM,DSSS
38
140
n
2.4/5
100-200+
20-40
4
OFDM
70
250


802.11 a, g and n allows for more simultaneous users, while 802.11b allows for fewer simultaneous users.  802.11b and g (and if using 2.4 GHz frequency for n) uses the 2.4 GHz frequency (the same as many microwave, ovens, cordless phones, and other appliances) which can cause interference. We can avoid these by using a cordless phone with a higher frequency such as 5.8 GHz. 802.11 a and n uses 5 MHz frequency, which limits interference from other devices. 802.11a has s shorter signal range, which is more easily obstructed by walls and other obstacles. It is not compatible with 802.11b network adapters, routers and access points. 802.11g has good signal strength, is not easily obstructed and is compatible with 802.11b network adapters, routers and access points. 802.11n has the fastest speed. It uses multiple signals and antennas for better speed. It has the best signal range and isn’t easily obstructed. If using 2.4 GHz frequency, it is compatible with 802.11g network adapters, routers and access points.

The best wireless interface is the 802.11n as it has the fastest maximum speed and best signal range. It is more resistant to signal interference from outside sources. It was designed to improve on 802.11g in the amount of bandwidth supported by utilizing multiple wireless signals and antennas instead of one. But due to its high cost and low availability in India we use 802.11g as an alternative.

Now we learnt how to setup a wireless router in my computer. First we had to enable the Wi-fi broadband connection. For this we took a 450TC1 beetle modem and connected it to my pc via Ethernet cable. Then opened the browser and input http://192.168.1.1 at the address column.

Then we filled in the default user name and password provided in the manual of my router.







Then press enter.
Then in the INTERFACE SETUP tab, click on wireless.
It only had b and g interfaces. Then we contacted our service provider for all other details. We used WEP-128bits authentication type. Then saved it. Then to enable the Wi-fi connection, I did the following steps:

Go to control panel.
Then network and internet options.
Then network and sharing center.
Then change adapter settings.
Then click on the available wireless network connection.
Click on its properties.
Then go to properties of TCP/IPV4/6.
Then I checked the connection from bottom right corner of desktop.
It enabled the 802.11 g type interface.

To enable the wireless connection in linux:
Then
And then saving it would enable the wireless connection in ubuntu.

To change from one interface to other available interface,

Go to control panel -> device manager
We can modify the interface based upon our needs.

For 802.11g, I checked the range and speed in my home. The speed was 54.0Mbps. The signal strength was excellent when the laptop was near to the modem (10 m). But as I went far away (18 m) from the modem the strength reduced to good and then to poor (25 m) and then died out. Then we checked 802.11n interface in ratika’s home. The speed was 65.0Mbps. The signal strength was excellent till 15 m, but it grew to poor when we went far away from the modem (30 m) and then died.

This project helped us explain the differences between the interfaces, and which would be most suitable for different conditions.

References used:







Contributed by Prerna Singh and Ratika Kumar

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