Data Acquisition Web

Cellular telephony is just only one of a wide array of wireless technologies being developed at present time. Other technologies are wireless piconetworking (as exemplified by the Bluetooth radio-on-a-chip) and other personal area network (PAN) systems (e.g., the IEEE 802.15 family of standards), wireless local area network (LAN) systems (exemplified by the IEEE 802.11 and HiperLAN families of standards, called WiFi systems), wireless metropolitan area network (MAN) systems (exemplified by the IEEE 802.16 family of standards, called WiMax systems), other wireless local loop (WLL) systems, and a variety of satellite systems.

These technologies are supported by a number of transmission and channel-assignment techniques, including time-division multiple access (TDMA), code-division multiple access (CDMA), and other spread-spectrum systems, orthogonal frequency-division multiplexing (OFDM) and other multicarrier systems, and high-rate single-carrier systems.

These techniques are chosen primarily to address the physical properties of wireless channels, among the most prominent of which are multipath fading, dispersion, and interference. In addition to these temporal transmission techniques, there are spatial techniques, notably beam forming and space-time coding, that can be applied at the transmitter to exploit the spatial and angular diversity of wireless channels.

To obtain maximal benefit from these transmission techniques, to exploit the diversity opportunities of the wireless channel, and to mitigate the impairments of the wireless channel, advanced receiver signal processing techniques are of interest. These include channel equalization to combat dispersion, RAKE combining to exploit resolvable multipath, multiuser detection to mitigate multiple-access interference, suppression methods for co-channel interference, beamforming to exploit spatial diversity, and space-time processing to jointly exploit temporal and spatial properties of the signaling environment.