Hot Spots: Public Access using 802.11
James Keeler · Cambridge University Press eBooks · 2007
Introduction A Wi-Fi “Hot Spot” is the common term used to describe locations that provide public Internet access using IEEE 802.11a,b or g wireless Ethernet, otherwise known as “Wi-Fi” (Wireless Fidelity). Wi-Fi uses a wireless Ethernet protocol that comes in various flavors including the most popular 802.11b/g, both of which operate in the 2.4 GHz frequency band of unlicensed spectrum. 802.11b can transmit/receive up to 11 megabits/second and 802.11g can transmit/receive up to 54 megabits/second. The new proposed 802.11n standard uses multi-path capabilities to transmit/receive at up to 155 megabits/second. 802.11a is a close cousin to 802.11g, with transmit/receive speeds of up to 54 megabits/second, but 802.11a runs in the 5 GHz unlicensed band. Most hotspots provide 802.11b and 802.11b/g (dual-mode capable) access – that is, the access points have radios that are able to function with either 802.11b or 802.11g connections. Some access points have tri-mode radios that run in 802.11a/b/g modes. Wi-Fi has become extremely popular. Whereas 8 years ago, 802.11b was on the fringe edge of techno-geek toys with only a few thousands of devices sold, now more than 90% of the mobile computers shipped by Dell, HP and IBM (Lenovo) come with 802.11b/g built in (many also with 802.11a forming tri-mode radios). Hence, there are hundreds of millions of laptop computers with Wi-Fi built in. Those that do not have it built in can add it on with a PCMCIA card or USB drive device for less than $30.00.