Accompanying the current Internet revolution, the wireless revolution is also having a profound impact on the way people work and live. Today, more people in Europe have a mobile phone than a PC or a car. And the wireless trend is continuing with many analysts predicting that wireless (and often mobile) handheld devices -- such as mobile phones and PDAs-.will overtake wired computers as the dominant Internet access devices throughout the world. Today, there are two common types of wireless Internet access. In a wireless LAN, wireless users transmit/receive packets to/from a base station (also known as a wireless access point) within a radius of a few tens of meters. The base station is typically connected to the wired Internet and thus serves to connect wireless users to the wired network. In wide-area wireless access networks, packets are transmitted over the same wireless infrastructure used for cellular telephony, with the base station thus being managed by a telecommunications provider. This provides wireless access to users within a radius of tens of kilometers of the base station.
Wireless LANs, based on IEE 802.11 technology (also known as wireless Ethernet and WiFi), are currently enjoying widespread deployment in university departments, business offices, cafes, and homes. Many universities install IEEE 802.11 base stations across their campuses, allowing students to send and receive e-mail or surf the Web from anywhere on campus (for example, library, dorm room, classroom, or outdoor campus bench). In many cities, one can stand on a street corner and be within range of ten or twenty base stations (for a browse able global map of 802.11 base stations that have been discovered and logged on a Web site by people who take great enjoyment in doing such things, see [wiggle.net 20071). The most commonly deployed 802.11 technology.

Today many homes are combining broadband residential access (that is, cable modems or DSL) with inexpensive wireless LAN technology to create powerful home networks. This home network consists of a roaming laptop as well as a wired PC; a base station (the wireless access point), which communicates with the wireless PC; a cable modem, providing broadband access to the Internet; and a router, which interconnects the base station and the stationary PC With the cable modem. This network allows household members to have broadband access to the Internet, with one member roaming from the kitchen to the backyard to the bedrooms. The total fixed cost for such a network is less than $150 (including the cable/DSL modem). When you access the Internet through wireless LAN technology, you typically need to be within a few tens of meters of a base station. This is feasible for home access, coffee shop access, and, more generally, access within and around a building. But what if you are on the beach or in your car and you need Internet access? For such wide-area access, roaming Internet users make use of the cellular phone infrastructure, accessing base stations that are up to tens of kilometers away. Conceptually, this is similar to a home user with a dial-up connection to the Internet over a wired telephone line, except that now the cellular telephony infrastructure, rather than the wired telephony infrastructure, is used.

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