Help with OFDM:trouble with orthogonality

[ahamshubham]

I am new to OFDM and I did not understand the concept of orthogonality being used in OFDM......
In OFDM, the channel is divided into bands with different carrier frequencies and these carrier frequencies are orthogonal to each other so they do not interfere with each other. How does this take place and what happens to orthogonality when the message signals are also dumped onto the carriers?
Please help.
(Even links would be a great option : simple mathematical approach would be highly appreciated)

 

[kripacharya]

don't get confused by the word "orthogonal".
Here's what happens in simpler (?) words ... and based on understanding of the Sinc function.

if you space the subcarriers from one another by any amount equal to the reciprocal of the symbol period of the data signals, the resulting sinc (sin x/x) frequency response curve of the signals is such that the first nulls occur at the subcarrier frequencies on the adjacent channels. The subcarriers all have an integer number of cycles within the symbol period. With this arrangement, the modulation on one channel won’t produce intersymbol interference (ISI) in the adjacent channels.

hope this helps

 

[ahamshubham]

Thank you very much. I found your answer quite helpful but can I get a more mathematical proof kind of somewhere explaining it......