OFDM(Orthogonal Frequency Division Multiplexing)即正交频分复用技术，实际上OFDM是多载波调制的一种。其主要思想是：将信道分成若干正交子信道，将高速数据信号转换成并行的低速子数据流，调制到在每个子信道上进行传输。正交信号可以通过在接收端采用相关技术来分开，这样可以减少子信道之间的相互干扰 ICI 。每个子信道上的信号带宽小于信道的相关带宽，因此每个子信道上的可以看成平坦性衰落，从而可以消除符号间干扰。而且由于每个子信道的带宽仅仅是原信道带宽的一小部分，信道均衡变得相对容易。-OFDM (Orthogonal Frequency Division Multiplexing) that is orthogonal frequency division multiplexing, in fact, is a multi-carrier OFDM modulation. The main idea is: The channel is divided into a number of orthogonal sub-channel, high-speed data signal into parallel low-speed data streams, modulated to be transmitted on each subchannel. Quadrature signal at the receiving end can be separated using technologies, which can reduce the mutual interference between ICI subchannels. The signal bandwidth of each subchannel is less than the channel coherence bandwidth, and therefore can be regarded as flat fading on each sub-channel, thereby eliminating inter-symbol interference. And because the bandwidth of each subchannel is only a small part of the original channel bandwidth, channel equalization becomes relatively easy.