说明：  此程序参照了IEEE 802.11a ，使用了52个子载波。理论期望papr为52.但是由加扰器的存在，所有子载波很难一直的调制
(Per the IEEE 802.11a specifications, we 52 have used subcarriers. Given so, the theoretical maximum expected PAPR is 52 (around 17dB). However, thanks to the scrambler, all the subcarriers in an OFDM symbol being equally modulated is unlikely. )