直接序列扩频编码捕捉的研究

【作者】 吴明立；

【导师】 屈玉贵；

【作者基本信息】 中国科学技术大学 ， 通信与信息系统， 2006， 硕士

【摘要】 扩频通信由于其具有优越的抗干扰特性和多址能力，在通信、医疗、测控中得到广泛的应用。对扩频码的捕获和跟踪一直是扩频通信重点研究的问题，捕获时间的长短是衡量扩频通信系统性能的一个重要指标。 现有的扩频码的捕捉方法有它们的优点，也有它们的不足：传统的滑动相关法要实现快速捕捉就需要大量的硬件，采用较小的硬件时又要较长的时间，在此基础上发展起来的串行积分和并行积分性能有一定的提高，但都不是很理想，SAW器件捕捉法能实现快速捕捉，担捕捉位数小于256位。在直扩编码的捕捉方法中，序贯捕捉法不失为一种较好的捕捉方法，与相关捕捉法相比速度能提高2至10倍，也不需要增加太多的硬件结构。 本文首先阐述了扩频通信的基础知识，再对目前主要的直接序列扩频编码捕捉方法进行了总结、比较，分析了各自的优劣，最后提出了一种改进的捕捉结构，即并行序贯检测捕捉结构。该结构能在适当增加硬件规模的情况下，很好地提高捕获的速度，并对提出的方法进行了理论分析，得出了捕获时间和各参数关系。 文章还对宽间隔跳频进行了介绍，针对我们常用的宽间隔跳频增益算法存在的问题，采用修正算法对宽间隔跳频增益进行了计算，同时分析了误码率及抗干扰能力。 同时还提出了子载波选择情况下MC-CDMA的通信方法，它是针对多载波CDMA通信的部分子载波存在深度衰落的情况，提出了子载波选择的通信方法，抛弃处于深度衰落的子载波。在发射端采用相同的功率情况下，子载波选择的方法比采用全部载波传输的方法有更高的信噪比和更低的误码率。更多还原

【Abstract】 Because of having ascendant anti-jamming characteristic and multi-address capability in spread spectrum communication, it extensive have application in communication, medical treatment, measure and control. It is stress research problem to spread spectrum code acquisition and synchronization, acquisition time is important standard of spread spectrum communication performance.In the acquisition ways of the direct sequence spread spectrum code at present, all have their merit and shortage: traditional slippage correlation way need massive hardware scale to realization fast acquisition, serial integral and parallel integral have much less time than slippage correlation way, but their improve didn’t excellence, SAW can application PN code quickly, but PN code digit less 256. In the acquisition ways of the direct sequence spread spectrum code, Sequence probability ratio test(SPRT) acquisition is a better way, acquisition time reduced 2 to 10 times compared with correlation acquisition way. It will improve the acquisition speed bigger if the hardware scale is appropriately added.In this paper, expatiated spread spectrum communication basis knowledge at first, summarized and compared to mostly direct spread spectrum code acquisition ways at present the second, at last, forward a new acquisition structure, namely parallel SPRT acquisition. It will improve the acquisition speed bigger if the hardware scale is appropriately added, and acquire the relation of acquisition time and parametersIntroduced wide interval frequency hopping in this paper also,. Aim at the problem of wide interval Frequency Hopping Processing Gain arithmetic in the common used, adopt modificatory arithmetic and calculated wide interval Frequency Hopping Processing Gain, analysis BER and anti-jamming ability.Aim at partly sub-carrier have deeply fading in MC-CDMA communication, proposed sub-carrier selection way. Transmitted the same power ,the way of sub-carrier selection have even better SNR and lower BER than using all sub-carrier.更多还原