一个OFDM符号128个有效符号，插入128个虚拟子载波

符号率（即有效数据率）fsymbol，而发送速率（需要包括虚拟子载波）2fsymbol

输入的数据需要2倍的发送数据率，以便进行内插，实现位定时跟踪，即4倍fsymbol采样率的调制信号

OFDM symbol Nfft=128 points

一个OFDM符号数据点 Nfft*2 = 256 ， Guard Interval点 ＝Ng*2=64

-128　of an OFDM symbol of a valid symbol 128 inserted virtual sub-carrier

Symbol rate (the effective data rate) fsymbol sending rate (including virtual subcarriers) 2fsymbol

　Of the input data needs to be 2 times the transmission data rate, in order to carry out the interpolation, to achieve the bit timing tracking, i.e. four times the sampling rate modulation signal fsymbol

　OFDM symbol Nfft = 128 points

　One OFDM symbol data points nfft* 2 = 256, the Guard Interval dot = Ng* 2 = 64