一种利用约束Viterbi算法改进IS95协议信道编码的方法

IS95具有两个速率集,在同一个速率集中,不同的速率其数据帧的长度不同,为了使进入正交调制的数据帧的长度相同,其采用了信号重复器.信号重复器进行简单的重复作用,使得带宽不能充分利用.文中提出的方法利用一个信号发生器,产生已知的信号进入卷积编码,卷积编码后的数据帧长度同样符合要求,而信号发生器产生的已知信号在译码端可以作为译码时的约束条件进行约束Viterbi译码.在BSC信道模型的仿真结果证明,其在较高误码率的情况下具有较好的性能.

A Scheme for Improving the Channel Coding Performance in IS95 Protocol by Using Constrained Viterbi Algorithm

IS95 protocol has two rate sets, in each rate set, different rate has different frame length. In order to adjust the frame length to the same, a symbol repeater is used, which just repeats the symbol simply, and the bandwidth is not fully made use of. In the scheme proposed in this paper, a symbol generator is used to produce some known symbols, this known symbol sequence is taken as an input to convolutional encoder, and makes the length of data frames after encoder meet the requirement of IS95 protocol. Since the constrained Viterbi algorithm is used in the be regarded as useful contrained conditons and result over BSC channel shows that this scheme is high. receiver, those symbols produced by symbol generator can improve the decoding performance greatly. The simulation can achieve good performance when the channel error rate is high.