Wireless..

Wireless Standards!

802.11b cards can operate at 11 Mbps, if signal quality becomes an issue. Since the lower data rates use less complex and more redundant methods of encoding the data, they are less susceptible to corruption due to interference and signal attenuation.

 802.11a standard uses the same core protocol as the original standard, operates in 5 GHz band, and uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) with a maximum raw data rate of 54 Mbps. This yields realistic net achievable throughput in the mid-20 Mbps. The data rate is reduced to 48, 36, 24, 18, 12, 9 and then, 6 Mbps if required.However, this high carrier frequency also brings disadvantages.

It also means that 802.11a cannot penetrate as far as 802.11b/g since it is absorbed more readily, other things (such as power) being equal.

802.11g attempts to combine the best of both 802.11a and 802.11b,supports bandwidth up to 54 Mbps, and it uses the 2.4 Ghz frequency for greater range. 802.11g is backwards compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.

 802.11n real data throughput or data transfer speed is estimated to reach a theoretical 540 Mbps (which may require an even higher raw data rate at the physical layer). This is up to 100 times faster than 802.11b and well over 10 times faster than 802.11a or 802.11g. 802.11n also offers a better operating distance or range than current networks.

 802.11n builds upon previous 802.11 standards by adding MIMO (multiple-input multiple-output). The MIMO technology uses multiple transmitter and receiver antennas to increase data throughput or data transfer rates through spatial multiplexing. By exploiting spatial diversity, perhaps through coding schemes like Alamouti coding, MIMO also increases a network’s range.