中文说明：在PLC信道中，OFDM的整个收发系统，包括编码、调制、插入导频、IFFT、插入循环前缀等操作，并且图示了信号的变化情况。
English Description：
In the PLC channel, the OFDM of the entire transceiver system, including coding, modulation, insert pilot, IFFT, insert the cyclic prefix and other operations, and illustrated the changes in the signal.