低信噪比下超长PN码的快速捕获技术  

Fast Acquisition Technique of Long PN Code With Low Signal-to-Noise Ratio

作　　者：刘震昆[1] 黄顺吉[1] 

机构地区：[1]电子科技大学电子工程系,四川成都610054

出　　处：《信号处理》2006年第3期299-302,共4页Journal of Signal Processing

摘　　要：直扩系统中,为了硬件实现上的简便,PN码的捕获一般都采用串行搜索的方法。但当PN码很长时,由于要搜索的相位点很多,串行搜索法将使捕获时间过长。并且当信噪比较低时,会有较高的虚警概率。这些都会使系统的捕获性能下降。文献[6]针对长码提出了分布采样的快速捕获方案(DSA)。本文就此提出了改进,利用积累使之能够适应低达-50dB的低信噪比环境。仿真结果表明,改进后的算法改善了原算法在极低信噪比下的性能,降低了平均捕获时间。In DS-CDMA systems,in order to simplify the hardware implementation,people usually adopt serial search（SSA） to synchronize PN code. But when PN code is very long,SSA will spend more time because there are many phase position to be cmopared. Specially, when the signal-to-noise is very low, the false alarm probability will be very high. All these factor will strongly debase acquisitive performance. Literature[ 6 ] proposed a new acquisition scheme called distributed sample acquisition（DSA） which＇is applicable to a long period PN code. We improve the scheme by accumulator,and make it available in -50dB＇ s Low SNR environment. The result of simulation proves that our improvement meliorates the old scheme＇ s performance with low SNR, and reduces the average acquisitive time.

关 键 词：直扩系统 分布式采样捕获 积累 平均捕获时间 

分 类 号：TN925[电子电信—通信与信息系统] TN914.42[电子电信—信息与通信工程]