Mathematical modeling and performance analysis for a two-stage acquisition scheme for direct-sequence spread-spectrum CDMA
Mathematical modeling and performance analysis for a two-stage acquisition scheme for direct-sequence spread-spectrum CDMA
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直接序列扩频CDMA两级采集方案的数学建模和性能分析
DOI：
10.1109/26.412726
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
M. Pursley
中科院分区：
文献类型：
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作者：
Upamanyu Madhow;M. Pursley
研究了DS/SS CDMA系统的同步捕获问题。对于具有大的定时不确定性的大系统，先前已经表明，在存在多址干扰的情况下的捕获可能对容量施加显著限制。这导致作者考虑一个系统中的定时不确定性是相对较小的，并提出了一个收购计划，利用这一点，以减少复杂性和收购开销。该建议可能适用于个人通信的微蜂窝环境，其中CDMA分组传输用于语音和数据。分组化传输意味着可用于捕获的开销很小，并且大量的微小区将限制每个微小区中的接收机中使用的捕获方案的成本。因此，简单的串行搜索方案所需的捕获时间可能大得不可接受。另一方面，虽然使用无源匹配滤波器的捕获是快速的，但是可靠捕获所需的滤波器长度在成本和复杂性方面易于过大。出于这些考虑，作者提出了一个两阶段的收购计划，采用了一个短的可编程匹配滤波器的初始检测，随后由相关器进行验证。数值结果的基础上，在多址干扰的存在下的捕获性能的近似分析比较该方案与传统的捕获方案。>
Acquisition of synchronism is considered for DS/SS CDMA systems. For large systems with large timing uncertainties, it has been shown previously that acquisition in the presence of multiple-access interference may impose a significant limitation on capacity. This leads the authors to consider a system in which timing uncertainties are relatively small and to propose an acquisition scheme which exploits this to reduce complexity and acquisition overhead. The proposal may be appropriate for a microcellular environment for personal communications in which CDMA packet transmission is employed for both voice and data. Packetized transmission would imply that the overhead available for acquisition is small, and the large number of microcells would restrict the cost of the acquisition scheme used in the receiver in each microcell. The acquisition time required for a simple serial search scheme may therefore be unacceptably large. On the other hand, while acquisition using a passive matched filter is fast, the filter length required for reliable acquisition is liable to be excessive in terms of cost and complexity. Motivated by these considerations, the authors propose a two-stage acquisition scheme which employs a short programmable matched filter for initial detection, followed by a correlator for verification. Numerical results based on an approximate analysis of acquisition performance in the presence of multiple access interference are employed to compare the scheme with conventional acquisition schemes. >