Wireless LAN’s

WIRELESS LAN’S

Wireless technologies differ in variety of dimensions, most notably in how much bandwidth they provide and how far apart communicating nodes can be. Other important differences include which part of the electromagnetic spectrum they use (including whether it requires a license) and how much power they consume. Four prominent wireless technologies:

► Blue tooth

► Wi-Fi(more formally known as 802.11)

► WiMAX(802.16)

► Third generation or 3Gcellular wireless.

The most widely used wireless links today are usually asymmetric, that is, the two endpoints are usually different kinds of nodes.

BASE STATION, usually has no mobility, but has a wired (or at least high bandwidth) connection to the internet or other networks.

A “client node” is often mobile, and relies on its link to the base station for all its communication with other nodes. Wireless communication naturally supports point to multipoint communication, because radio waves sent by one device can be simultaneously received by many devices. However, it is often useful to create a point to point link abstraction for higher layer protocols.

This topology implies three qualitatively different levels of mobility. The first level is no mobility, such as when a receiver must be in a fixed location to receive a directional transmission from the base station, as is the case with the initial version of WiMAX. The second level is mobility within the range of a base, as is the case with Bluetooth. The third level is mobility between bases, as is the case with cell phones and Wi-Fi.