As the question , I don't really understand what is a wireless channel.
Supposed we have an access point with the standard 802.11b, it will use the frequency 2.4 GHz –>Is this the bandwith? And the transfer rate of this standard is 11 Mbps. What is the relationship between them? and why do we have to divide the bandwith into different channels?
Can anyone give me a briefly bottom-up concept about these concepts?
Thanks in advanced.
Best Answer
When it says 2.4 GHz, it means the band between 2.4 GHz and 2.5 GHz (the exact range varies from one country to another). It's a similar idea to the allocation to CB radio of channels around 27 MHz.
Now, a single frequency just gives you a carrier; you need to modulate it to send information. If you looked at the signal with a spectrum analyzer, the sharp peak of the carrier will be broadened. This frequency spread is what analogue engineers call the bandwidth: 22 MHz in the case of 802.11b.
Networking people usually quote bandwidth in terms of bits/second; the exact relationship between frequency and bits/second depends on the encoding used. For 802.11b, divide by two: later standards tend to have more complex and efficient encodings.
The advantage of having multiple channels is that you can get aggregate performance of more than 11 Mbps by staggering the frequencies. In a corporate deployment with many APs, adjacent APs will operate on non-overlapping channels, as far as possible.
Stealing gio's link: en.wikipedia.org/wiki/List_of_WLAN_channels