Wi-Fi (short for "wireless fidelity") is the popular term for a high-frequency wireless local area network (WLAN). The term is used by the Wireless Ethernet Compatibility Alliance to describe wireless networking technology. The Wi-Fi technology is rapidly gaining acceptance in many companies as an alternative to a wired LAN. It can also be installed for a home network. Wi-Fi is specified in the 802.11b specification from the Institute of Electrical and Electronics Engineers (IEEE) and is part of a series of wireless specifications together with 802.11, 802.11a, and 802.11g. All four standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.
How it works
Instead of moving data through a network using Ethernet cable, Wi-Fi (802.11b) technology uses radio waves in the 2.4-GHz spectrum to move data across different frequencies. Meaning, it can operate in the 2.4 GHz range offering data speeds up to 11 megabits per second. This is the same range used by your cordless phone. And like a cordless phone's signal, its signal can be distorted by large objects and walls.
The modulation used in 802.11 has historically been phase-shift keying (PSK). The modulation method selected for 802.11b is known as complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference.
Unless adequately protected, a Wi-Fi wireless LAN can be susceptible to access from the outside by unauthorized users, some of whom have used the access as a free Internet connection. (The activity of locating and exploiting security-exposed wireless LANs is commonly known as war driving and an identifying iconography has developed that is known as warchalking.) Companies that have a wireless LAN are urged to add security safeguards such as the Wired Equivalent Privacy (WEP) encryption standard, the setup and use of a virtual private network (VPN) or IPsec, and a firewall or DMZ.
Many airports, hotels, and fast-food facilities now offer public access to a Wi-Fi network; these are known as hotspots. Although many charge a daily or hourly rate for access, some are free.
The best way for consumers to use this technology is to tap into a high-speed Internet connection. A wireless access point remains hooked up to your wired network (broadband connection). If you have the right PC card, your laptop, PC, or personal digital assistant (PDA) can get the signal. Certain cafĂ©s, airports, and universities let you tap into their wireless network so you can get Internet access on your Wi-Fi-equipped laptop.
The data transfer rate is usually between 4 Mbps and 5 Mbps, although TechTV Labs has seen rates reach 7 Mbps to 8 Mbps. Your typical broadband connection offers 1.5 Mbps.