说明：  提高数据传输效率，降低误码率是信道编码的任务。信道编码的本质是增加通信的可靠性。但信道编码会使有用的信息数据传输减少，信道编码的过程是在源数据码流中加插一些码元，从而达到在接收端进行判错和纠错的目的
(Improve the efficiency of data transmission, reduce the bit error rate is the channel coding task. The essence of channel coding is to increase the reliability of communication. But the channel coding can make data transmission of useful information is reduced, the channel coding process is to add some symbols in the source data stream, so as to achieve the purpose of erroneous judgment and correction at the receiver)