标题: | 宽频分码多工之复乱码撷取系统的性能分析 Performance Analysis of Complex Code Acquisition for a Broadband CDMA System |
作者: | 林渊斌 Yuan Pin Lin 苏育德 Yu Ted Su 电信工程研究所 |
关键字: | 复乱码;撷取;同步;展频;分码多工;complex code;acquisition;synchronization;spread spectrum;cdma |
公开日期: | 2000 |
摘要: | 本篇论文探讨一宽频分码多工(CDMA)之复乱码粗调撷取系统(Code Acquistion System)在复径衰褪(Multipath Fading)以及多工干扰(Multiple Access Interference)下的性能分析。 不论欧盟与日本之WCDMA或美国之cdma-2000,都采用complex spreading/QPSK以达到降低传送讯号PAR (peak-to-average ratio)并提高功率效率之目的。在本篇论文的分析与传统的分析主要相异,在于我们考虑了通道衰褪及多工干扰所造成的统计相关性。我们修正了早先较粗略的马可夫模式并利用Royan 氏的结果来计算出精确的平均码撷取时间 (Mean Acquisition Time)。 本论文所考虑的宽频分码多工系统为cdma2000上行链路(Reverse Link)系统。而所采用的撷取方法则为码匹配滤波器(PN Code Matched filter)。这种方式可在宽频多工的环境下迅速的完成乱码撷取。 This thesis studies the code acquisition subsystem performance of the reverse link of the IS-2000 (previous known as cdma2000) radio interface in which complex sequence spreading is used to minimize the peak-to-average (PAR) ratio. Our work focuses on the analysis of the mean acquisition time performance, assuming a correlated Rayleigh multipath fading environment. Code acquisition is the most crucial step in setting up a direct sequence spread spectrum (DS/SS) communication link. Extensive researches have been carried out to study the performance of various code acquisition schemes. This thesis considers the one that uses pseudo-noise matched ?lter (PNMF) detectors for its rapid acquisition capability. Our analysis di?ers from earlier approaches in that we take into account the statistical correlation among the matched ?lter outputs corresponding to di?erent code phase positions. The correlation is due to the higher-than-1 sample/chip sampling rate and the channel e?ects such as multipath fading and multiple access interference from other users. We modify and extend the Markov chain model used by the conventional approach to take the detector output correlation into consideration. The results of Ruyen are then applied to evaluate the associated probabilities and whence the acquisition time performance. Numerical examples demonstrate that our analysis yields very accurate performance prediction while the conventional approach often gives too optimistic pre- diction. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT890435102 http://hdl.handle.net/11536/67382 |
显示于类别: | Thesis |