# Why does the 802.11b DSSS signal have 22 MHz of channel width? How does the information get spread over that width? [duplicate]

This topic has got me so much confused.

In terms of Wi-Fi, when we say the 802.11b has 22 MHz of Channel Bandwidth, what does it mean? When we refer to a particular Channel No. say Channel 1, it has its center frequency of 2412 MHz, but it spans from 2401 MHz (-11 MHz) to 2423 MHz (+ 11 MHz) to form a 22 MHz channel. Why is that? Why can't the channel be just 2412 MHz signal?

How does the data utilize the 22 MHz width?

Also how does increasing the Bandwidth help in increasing the throughput (not data rate)? No highway examples please, because those are layman and incorrect analogies.

Thanks

• Because a pure 2412 MHz sine wave carries no information. And you'll find that any signal which is not a pure sine wave has nonzero bandwidth. Apr 12 '16 at 22:54
• How does the data/information get spread over a 22 MHz width then?
– eecs
Apr 12 '16 at 22:55
• Not a snark answer! Wikipedia knows all. en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29
– user65586
Apr 12 '16 at 23:15
• It's not intuitive to understand just by knowing B.W. is difference between highest and lowest frequency. My question is what are the factors which decide how wide the channel should be? And how does the information/data gets spread over it? Channel is a set of frequencies. But when we always point out to the center frequency.
– eecs
Apr 12 '16 at 23:20
• Don't think of it as "how does increasing the bandwidth increase the data rate?"; think of it as "how does increasing the data rate increase the bandwidth?" Apr 13 '16 at 2:10