<P> Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively unused 5 GHz band gives 802.11 aa significant advantage . However, this high carrier frequency also brings a disadvantage: the effective overall range of 802.11 a is less than that of 802.11 b / g . In theory, 802.11 a signals are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength, and, as a result, cannot penetrate as far as those of 802.11 b . In practice, 802.11 b typically has a higher range at low speeds (802.11 b will reduce speed to 5.5 Mbit / s or even 1 Mbit / s at low signal strengths). 802.11 a also suffers from interference, but locally there may be fewer signals to interfere with, resulting in less interference and better throughput . </P> <P> The 802.11 b standard has a maximum raw data rate of 11 Mbit / s, and uses the same media access method defined in the original standard . 802.11 b products appeared on the market in early 2000, since 802.11 b is a direct extension of the modulation technique defined in the original standard . The dramatic increase in throughput of 802.11 b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11 b as the definitive wireless LAN technology . </P> <P> Devices using 802.11 b experience interference from other products operating in the 2.4 GHz band . Devices operating in the 2.4 GHz range include microwave ovens, Bluetooth devices, baby monitors, cordless telephones, and some amateur radio equipment . </P> <P> In June 2003, a third modulation standard was ratified: 802.11 g . This works in the 2.4 GHz band (like 802.11 b), but uses the same OFDM based transmission scheme as 802.11 a . It operates at a maximum physical layer bit rate of 54 Mbit / s exclusive of forward error correction codes, or about 22 Mbit / s average throughput . 802.11 g hardware is fully backward compatible with 802.11 b hardware, and therefore is encumbered with legacy issues that reduce throughput by ~ 21% when compared to 802.11 a . </P>

What is the frequency and maximum data rate for 802.11b