Wireless Network Topologies

[Eranda]

As wireless sensors are the most widespread networking technology in the present world and its become a practical option, sensor networks take on a whole new dimension. The problem arises: How can traditional network topologies be modified to the new infrastructure medium?

 

[Eranda]

WiFi is the wireless way to grip networking. It is also known as 802.11 networking and wireless networking. The main benefit of WiFi is its effortlessness. You can connect computers anywhere in your home ,factory or office without the need for wires. The computers connect to the network using radio signals, and computers can be up to 100 feet or so apart.---

WiFi's Radio Technology

• WiFi radios that work with the 802.11b and 802.11g standards transmit at 2.4 GHz, while those that comply with the 802.11a standard transmit at 5 GHz. Normal walkie-talkies normally operate at 49 MHz. The higher frequency allows higher data rates.
• WiFi radios use much more efficient coding techniques that also contribute to the much higher data rates. For 802.11a and 802.11g, the technique is known as orthogonal frequency-division multiplexing (OFDM). For 802.11b, it is called Complementary Code Keying (CCK). See this page for details.
• The radios used for WiFi have the ability to change frequencies. 802.11b cards can transmit directly on any of three bands, or they can split the available radio bandwidth into dozens of channels and frequency hop rapidly between them. The advantage of frequency hopping is that it is much more immune to interference and can allow dozens of WiFi cards to talk simultaneously without interfering with each other.

Eranda Sooriyapperuma from Switzerland

 

[Eranda]

• 802.11b was the first version to reach the marketplace. It is the slowest and least expensive of the three. As mentioned above, 802.11b transmits at 2.4 GHz and can handle up to 11 megabits per second.
• 802.11a was next. It operates at 5 GHz and can handle up to 54 megabits per second.
• 802.11g is a mix of both worlds. It operates at 2.4Ghz (giving it the cost advantage of 802.11b) but it has the 54 megabits per second speed of 802.11a.

Eranda Sooriyapperuma

 

[Eranda]

WiFi Security

WiFi protection
WiFi hotspots can be open or secure. If a hotspot is unlock, then anyone with a WiFi card can access the hotspot/ Acssespoint . If it is secure, then the user needs to know a WEP key /the Network Key to connect.
WEP stands for Wired Equivalent Privacy, and it is an encryption system for the data that 802.11 sends through the air. WEP has two variations: 64-bit encryption (really 40-bit) and 128-bit encryption (really 104-bit). 40-bit encryption was the original standard but was found to be easily broken. 128-bit encryption is more secure and is what most people use if they enable WEP I can recommend it also .
For a casual user, any hotspot that is using WEP is inaccessible unless you know the WEP key.
If you are scenery up a hotspot/Accesses point in your home, you may want to create and use a 128-bit WEP key to prevent the neighbors from casually eavesdropping on your network.
Whether at home or on the road, you need to know the WEP key, and then enter it into the WiFi card's software, to gain access to the network.