在实际的通信中，理想环境是不可能存在的，实际的通信系统会由于各种失真引起性能的恶化，接收机会无法准确同步发射机的相关参数。在实际的通信中需要考虑如下问题：(In actual communication, the ideal environment is impossible, and the actual communication system will deteriorate because of various distortions, and the receiving opportunity can not accurately synchronize the parameters of the transmitter. The following problems need to be considered in actual communication:)