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If you want to have a network in your home or office, you can connect the computers together using a wireless network also known as 802.11 networking and WiFi. (Wireless Fidelity). You can connect computers anywhere in your home 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. Wi-Fi (Wireless Fidelity) is a logo and term given to any IEEE 802.11 wireless network product that is certified to conform to specific interoperability standards. Wi-Fi Certification comes from the Wi-Fi Alliance, a nonprofit international trade organization that tests 802.11-based wireless equipment to ensure it meets the Wi-Fi standard. To wear the Wi-Fi logo, an 802.11 networking product must pass specific compatibility and performance tests, which ensure that the product will work with all other manufacturers' Wi-Fi equipment on the market. This certification arose from the fact that certain ambiguities in the 802.11 standards allowed for potential problems with interoperability between devices. By purchasing only devices bearing the Wi-Fi logo, you ensure that they will work together and not fall into loopholes in the standards. The most common forms of wireless networking in the United States and Canada are built around various versions of the IEEE 802.11 wireless Ethernet standards, including IEEE 802.11b, IEEE 802.11a, and the newer IEEE 802.11g standard. In Europe, HiperLAN, which has performance and frequency usage similar to that of 802.11a, is the wireless networking standard. In the past, Wi-Fi has been used as a synonym for IEEE 802.11b hardware. Because the Wi-Fi Alliance now certifies other types of 802.11 wireless networks, the term Wi-Fi should always be accompanied by the frequency band (as in Wi-Fi 2.4GHz band) to make it clear which products will work with the device. The new 802.11g wireless standard has the speed of 802.11a, but connects to 802.11b networks without special hardware. As 802.11g hardware passes Wi-Fi Alliance tests, it will also be known as Wi-Fi-compliant hardware.Here it is a table of 802.11-compliant networks: Table 20.9. IEEE 802.11-Based Wireless Networks IEEE Standard Maximum Speed Wi-Fi Alliance Term Number of Nonoverlapping Channels Also Known As Notes 802.11a 54Mbps 5GHz band 12 Wireless-A Dual-band hardware needed to connect with 802.11b 802.11b 11Mbps 2.4GHz band 3 Wireless-B Can connect with 802.11g; dual-band hardware needed to connect with 802.11b 802.11g 54Mbps 2.4GHz band 3 Wireless-G Can connect with IEEE 802.11b; dual-band hardware needed to connect with 802.11a

802.11 Network Hardware All types of 802.11 wireless networks have two basic components: * Access points * NICs equipped with radio transceivers An access point is a bookend-size device that uses an RJ-45 port to attach to a 10BASE-T or 10/100 Ethernet network (if desired) and contains a radio transceiver, encryption, and communications software. It translates conventional Ethernet signals into wireless Ethernet signals it broadcasts to wireless NICs on the network and performs the same role in reverse to transfer signals from wireless NICs to the conventional Ethernet network Access points are not necessary for direct peer-to-peer networking (also called ad hoc mode), but they are required for a shared Internet connection or a connection with another network. When access points are used, the network is operating in the infrastructure mode.Some access points can communicate directly with each other via radio waves, enabling you to create a wireless backbone that can cover a wide area, such as a warehouse, without the need to run any network cabling. NICs equipped for wireless Ethernet communications have a fixed or detachable radio antenna in place of the usual coaxial or RJ-45 port or dongle. Adding WiFi to a Computer One of the best things about WiFi is how simple it is. Many new laptops already come with a WiFi card built in -- in many cases you don't have to do anything to start using WiFi. It is also easy to add a WiFi card to an older laptop or a desktop PC. Here's what you do: * Buy a 802.11a, 802.11b or 802.11g network card. 802.11g has the advantage of higher speeds and good interoperability on 802.11b equipment. o For a laptop, this card will normally be a PCMCIA card that you slide into a PCMCIA slot on your laptop. Or you can buy a small external adapter and plug it into a USB port. o For a desktop machine, you can buy a PCI card that you install inside the machine, or a small external adapter that you connect to the computer with a USB cable. * Install the card * Install the drivers for the card * Find an 802.11 hotspot * Access the hotspot. A hotspot it is a acces point. There are many WiFi hotspots now available in public places like restaurants, hotels, libraries and airports. WiFi Security Because wireless networks can be accessed by anyone with a compatible NIC most models of NICs and access points provide for encryption options. Some devices with this feature enable you to set a security code known as an SSID on the wireless devices on your network. This seven-digit code prevents unauthorized users from sneaking onto your network and acts as an additional layer of security along with your normal network authentication methods, such as user passwords. Others use a list of authorized MAC numbers (each NIC has a unique MAC) to limit access to authorized devices only. All Wi-Fi products support at least 40-bit encryption through the wired equivalent privacy (WEP) specification, but the minimum standard on recent products is 64-bit WEP encryption. Many vendors offer 128-bit or 256-bit encryption on some of their products. Unfortunately, the WEP specification has been shown to be notoriously insecure against determined hacking.For that reason, many network products introduced in 2003 and beyond now incorporate a new security standard known as Wi-Fi Protected Access (WPA). WPA is derived from the developing IEEE 802.11i security standard. WPA-enabled hardware works with existing WEP-compliant devices, and software upgrades might be available for existing devices. You should match the encryption level and encryption type used on both the access points and the NICs for best security. Remember: If some of your network supports WPA but other parts support only WEP, your network must use the lesser of the two security standards (WEP). http://www.jaec.info

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Masterand - " STIC University" , Faculty of Electrical Engineering and Computer Science, Specialization Software Engineering web:www.jaec.info