超宽带跳时PPM信号在多径环境下的误码率性能优化

针对超宽带跳时PPM信号在不当参数选择时在确定性多径信道可能出现的不同数据符号的误码率不平衡性问题，提出解决TH-PPM调制信号可能存在误码率不平衡这一问题的两种方法，一种是Rake接收机选择动态的判决门限，另一种是改进TH-PPM调制方式，即对待发送的数据符号进行平衡编码。通过理论分析和计算机仿真表明，两种方法都能改善跳时PPM信号在多径环境下存在的误码率不平衡问题，比较而言，平衡编码方法具有实现的简单性以及在对信道变化、Rake接收机信道估计以及合并方式的稳健性。

BER performance optimization of ultra wideband TH PPM in multipath environment

Aiming at the unbalanced bit error rate for different transmitted data symbol of ultra wideband (UWB) impulse radio time-hopping pulse-position-modulation (TH-PPM) in deterministic multipath environment for unreasonable parameter selection,two solutions were presented in this work.One was that the decision threshold of Rake is dynamics for different channel environment;the other was that we can improve the traditional TH PPM modulation,that is,encoding the transmitted data symbol with balance code.It is shown by theoretical analysis and computer simulation that these two methods can solve the unbalanced bit error rate of traditional TH-PPM.Comparing with dynamic threshold method,the balance encoding scheme can be implemented more easily,and is more robust to the channel time variant characteristics,the channel estimation of Rake receiver and the combination techniques.