Wi-Fi

Introduction

Wi-Fi, or Wireless Fidelity, is a term that is used generically to refer to any product or service using any type of 802.11 technology. Wi-Fi networks operate in the unlicensed 2.4 and 5 GHz radio bands, with an 11 Mbps (802.11b) or 54 Mbps (802.11a) data rate, respectively.

Wi-Fi enabled devices (laptops or PDAs) can send and receive data wirelessly from any location equipped with Wi-Fi access. How? Access points, installed within a Wi-Fi location, transmit an RF signal to Wi-Fi enabled devices that are within range of the access point, which is about 300 feet. The speed of the transmission is governed by the speed of the pipeline fed into the access point. T-Mobile HotSpot service is unique in that every T-Mobile HotSpot service location is equipped with a full T-1 connection running to the access points.

With T-Mobile HotSpot service, a customer, once associated with the access point, can connect to the Internet and enjoy near T-1 speeds in the comfort of American Airlines Admirals Clubs, Starbucks coffeehouses, Borders Books & Music stores and numerous airports.

 

Lesson

Wi-Fi (short for "wireless fidelity") is the popular term for a high-frequency wireless local area network (WLAN). 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.
The 802.11b (Wi-Fi) technology operates in the 2.4 GHz range offering data speeds up to 11 megabits per second. 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.

Links

Secuirty Issue