Fixed Wireless Technologies

• In a fixed wireless network, both transmitter and receiver are at fixed locations, as opposed to mobile. The network uses utility power (AC). It can be point-to-point or point-to-multipoint, and may use licensed or unlicensed spectrums.

• Fixed wireless usually involves line-of-sight technology, which can be a disadvantage.

• The fresnel zone of a signal is the zone around the signal path that must be clear of reflective surfaces and clear from obstruction, to avoid absorption and reduction of the signal energy. Multipath reflection or interference happens when radio signals reflect off surfaces such as water or buildings in the fresnel zone, creating a condition where the same signal arrives at different times.

• Fixed wireless includes Wireless Local Loop technologies, Multichannel Multipoint Distribution Service (MMDS) and Local Multipoint Distribution Service (LMDS), and also Point-to-Point Microwave.

Developing WLANs through the 802.11 Architecture

• The North American wireless local area network (WLAN) standard is 802.11, set by the Institute of Electrical and Electronics Engineers (IEEE); HiperLAN is the European WLAN standard.

• The three physical layer options for 802.11 are infrared (IR) baseband PHY and two radio frequency (RF) PHYs. The RF physical layer is comprised of Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS) in the 2.4 GHz band.

• WLAN technologies are not line-of-sight technologies.

• The standard has evolved through various initiatives from 802.11b, to 802.11a, which provides up to five times the bandwidth capacity of 802.11b now, accompanying the ever growing demand...