Viterbi解码器的纠错门限及其对多用户检测的影响

多用户检测技术因可极大提高CDMA系统的容量而受到广泛关注．文中研究了结合前向纠错解码的多级并行干扰对消多用户检测器的性能，讨论了卷积码的纠错能力，给出了Viterbi解码器的输入和输出特性曲线，提出了viterbi解码器的纠错门限及其两种表示方法．系统仿真结果表明，接收信号的信干比低于Viterbi解码器的纠错门限时，多用户检测器将不能正常工作，在设计实际多用户检测接收机时要设法克服纠错门限造成的影响。

Error Correct Threshold of Viterbi Decoder and Its Influence on Multiuser Detection

Multiuser detection technique draws more and more attention because it can highly increase the capacity of CDMA system. This paper studies the performance of multiuser detector which combines multistage interfere canceling and forward error correction, discusses the error correcting capability of convolution code. In addition,it gives input vs output characteristics curve of Viterbi decoder, and puts forward error correct threshold of Viterbi decoder. The error correct threshold of Viterbi decoder can be expressed in either input bit error rate or input signal to noise ratio. System level simulation result shows: when the signal to interfere ratio of received signal is lower than the error correct threshold of the Viterbi decoder, the multiuser detector can not work normally. The effect of the error correct threshold of the Viterbi decoder should be taken into consideration when the multiuser detection receiver is designed.