A wide variety of different wireless data technologies now exist, some in direct competition with one another, others designed to be optimal for specific applications. Wireless technologies can be evaluated by a variety of different metrics described below.
Of the standards evaluated, these can be grouped as follows:
UWB, Bluetooth and Wireless USB are intended for use as so called Wireless PAN systems. They are intended for short range communication between devices typically controlled by a single person. A keyboard might communicate with a computer, or a mobile phone with a hands free kit, using any of these technologies.
Wi-Fi is the most successful system intended for use as a WLAN system. A WLAN is an implementation of a LAN over a microcellular wireless system. Such systems are used to provide wireless Internet access (and access to other systems on the local network such as other computers, shared printers, and oth er such devices) throughout a priv ate property. Typically a WLAN offers much better bandwidth and latency than the user's Internet connection, being designed as much for local communication as for access to the Internet, and while Wi-Fi may be offered in man y places as an Internet access system, access speeds are usually more limited by the shared Internet connection and number of users than the technology itself.
GPRS, EDGE and 1xRTT are bolt-ons to existing 2G cellular systems, providing Internet access to users of existing 2G networks (it should be noted that technically both EDGE and 1xRTT are 3G standards, as defined b y the ITU, but are generally deplo yed on existing networks.) 3G systems such as EV- DO, W-CDMA (including HSDPA and HSUPA) provide combined circuit switched and packet switched data and voice services as standard, usually at better data rates than the 2G extensions. All of these services can be used to provide combined mobile phone access and Internet access at remote locations. Typically GPRS and 1xRTT are used to provide stripped down, mobile phone oriented, Internet access, such as WAP, multimedia messaging, and the downloading of ring-tones, whereas EV-DO and HSDPA's higher sp eeds make them suitable for use as a broadb and replacement.
Pure pack et-switched only systems can be created using 3G network technologies, and UMTS- TDD is one example of this. Alternatively, next generation systems such as WiMAX also provide pure packet switched services with no need to support the circuit switching services required for voice systems. WiMAX is available in multiple configurations, including both NLOS and LOS variants. UMTS-TDD, WiMAX, and proprietary systems such as Canopy are used by Wireless ISPs to provide broadband access without the need for direct cable access to the end user.
Some systems are designed for point-to-point line-of-sight communications, such as RONJA and IrDA; once 2 such nodes get too far apart to directly communicate, they can no longer communicate. Other systems are designed to form a wireless mesh network using one of a variety of routing proto cols. In a mesh network, when 2 nodes get too far apart to directly communicate, they can still indirectly communicate through intermediate nodes