说明：  OFDM是将高速串行数据分成成百上千路并行数据,并分别对不同的载频进行调制,这种并行传输体制大大扩展了符号的脉冲宽度,提高了抗多径衰落的性能。同时,在传统的频分复用方法中,各子载波之间的频谱互不重叠,频谱利用率较低。而采用OFDM技术,一个OFDM符号之内包括多个经过调制的子载波的合成信号,每个子载波在频谱上相互重叠,这些频谱在整个符号周期内满足正交性,因而在接受端可以保证无失真恢复,从而大大提高频谱利用率。
(OFDM divides high-speed serial data into hundreds of parallel data channels and modulates different carrier frequency separately. This parallel transmission system greatly expands the pulse width of symbols and improves the performance of anti-multipath fading. At the same time, in the traditional method of Frequency Division multiplexing, the spectrum between the sub-carriers does not overlap each other, the spectrum utilization ratio is low. In the case of OFDM, an OFDM symbol consists of multiple modulated sub-carriers, each of which overlaps in the spectrum, which is orthogonal throughout the symbol period, thus, no distortion recovery can be ensured at the receiving end, thus greatly improving the spectrum utilization ratio.)