In reply to kunal.

Great Question! Thanks so much for asking this one-

There is no "Practical" difference between coverage of 802.11b and 802.11n or 802.11g for that matter. "practical" is the operative word here. In our Cisco AP3502 data sheets, if you look at 802.11b 1 Mbps, we can demodulate this down to -101 dBm vs 802.11n MCS0 at -93 dBm. But - what often gets ignored is SNR and both protocols require 0 dB SNR.

In a normal user environment, the noise floor will be at best -90, and often in congested environments -80 or worse. The the radio will not demodulate with a -20 dB SNR environment, it needs 0 dB worst case. So in practical terms - your usable coverage is the same.

Unless you are implementing in some place in the world (and I have seen them) where the noise floor is that of thermal noise only - you really should'nt see a measurable difference in the actual coverage - but the difference in efficiency massive. Thanks for reading.