| nying the current Internet revolution, the wireless | | | | base stations that have been discovered and |
| revolution is also having a profound impact on the | | | | logged on a Web site by people who take great |
| way people work and live. Today, more people in | | | | enjoyment in doing such things, see [wiggle.net |
| Europe have a mobile phone than a PC or a car. | | | | 20071). The most commonly deployed 802.11 |
| And the wireless trend is continuing with many | | | | technology. |
| analysts predicting that wireless (and often mobile) | | | | Today many homes are combining broadband |
| handheld devices -- such as mobile phones and | | | | residential access (that is, cable modems or DSL) |
| PDAs.will overtake wired computers as the | | | | with inexpensive wireless LAN technology to |
| dominant Internet access devices throughout the | | | | create powerful home networks. This home |
| world. Today, there are two common types of | | | | network consists of a roaming laptop as well as a |
| wireless Internet access. In a wireless LAN, | | | | wired PC; a base station (the wireless access |
| wireless users transmit/receive packets to/from | | | | point), which communicates with the wireless PC; |
| a base station (also known as a wireless access | | | | a cable modem, providing broadband access to |
| point) within a radius of a few tens of meters. | | | | the Internet; and a router, which interconnects |
| The base station is typically connected to the | | | | the base station and the stationary PC With the |
| wired Internet and thus serves to connect | | | | cable modem. This network allows household |
| wireless users to the wired network. In wide-area | | | | members to have broadband access to the |
| wireless access networks, packets are | | | | Internet, with one member roaming from the |
| transmitted over the same wireless infrastructure | | | | kitchen to the backyard to the bedrooms. The |
| used for cellular telephony, with the base station | | | | total fixed cost for such a network is less than |
| thus being managed by a telecommunications | | | | $150 (including the cable/DSL modem). When you |
| provider. This provides wireless access to users | | | | access the Internet through wireless LAN |
| within a radius of tens of kilometers of the base | | | | technology, you typically need to be within a few |
| station. | | | | tens of meters of a base station. This is feasible |
| Wireless LANs, based on IEE 802.11 technology | | | | for home access, coffee shop access, and, more |
| (also known as wireless Ethernet and WiFi), are | | | | generally, access within and around a building. But |
| currently enjoying widespread deployment in | | | | what if you are on the beach or in your car and |
| university departments, business offices, cafes, | | | | you need Internet access? For such wide-area |
| and homes. Many universities install IEEE 802.11 | | | | access, roaming Internet users make use of the |
| base stations across their campuses, allowing | | | | cellular phone infrastructure, accessing base |
| students to send and receive e-mail or surf the | | | | stations that are up to tens of kilometers away. |
| Web from anywhere on campus (for example, | | | | Conceptually, this is similar to a home user with a |
| library, dorm room, classroom, or outdoor campus | | | | dial-up connection to the Internet over a wired |
| bench). In many cities, one can stand on a street | | | | telephone line, except that now the cellular |
| corner and be within range of ten or twenty base | | | | telephony infrastructure, rather than the wired |
| stations (for a browse able global map of 802.11 | | | | telephony infrastructure, is used. |