Introduction - If you have any usage issues, please Google them yourself
The main purpose is to fight against multipath fading. Due to the presence of multipath fading, the first after they have the same frame different paths to reach the client delay. Would cause mutual interference between sub-carriers in the frequency domain, affecting performance. In addition, thanks to the cyclic prefix, so IFFT FFT operation to the linear convolution of the original into a circular convolution, greatly simplifying the corresponding signal processing complexity