说明：  利用matlab仿真了改进的二类选择重传HARQ机制的吞吐量与误比特率之间的关系。在仿真中对于编码和解码过程进行了简化：根据误比特率按概率模拟传输过程中码字的出错位数，在接收端只判断码字错误的位数是否在可纠错得范围之内。每发送一个码字，接收端根据出错位数信息检验其是否出错，没有出错则接收，否则要求重发，程序中利用alternate值交替发送信息码字和校验码字。当校验码字到来后，若校验码与原码组成的新码字能够纠错，则正确接收，否则要求重传。
(Retransmission the HARQ mechanism of throughput and bit error rate of the relationship between the use of matlab simulation improved second-class choice. In the simulation for the encoding and decoding process is simplified: digit of the code word of the error probability analog transmission process, according to the bit error rate of the receiving end only to determine the range of code word errors median whether error correction was. Each sending a code word, the information of the receiving end according to the error median test whether error, no error is received, or request retransmission, and the program using the alternate value alternately sent the information code word and the parity check code word. When the checksum word comes, if the new codeword able to check code with the original code error correction correctly received, otherwise require retransmission.)