直扩信号盲估计技术研究

发布时间：2018-01-06 09:04

本文关键词：直扩信号盲估计技术研究　出处：《电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：直扩通信凭借其传输信号具有低截获概率、抗窄带干扰、抗多径效应和多址复用等优点,广泛运用于军事通信。在低信噪比的非合作场景下,由于多用户信号的多维特征参数以及各个用户的扩频码序列不同而且均为未知,因此在这种情况下,要实现信号的截获然后进一步实现信号的盲解扩是非常困难的。同时现有盲估计系统获得的扩频序列估计常常含有误码,并不是真实扩频序列的准确估计。直扩信号盲估计的内容主要涉及信号检测、信号参数估计、伪码波形估计以及进一步的伪码序列无误码重构,传统的研究大多停留在单用户直扩信号的估计,而本文以多用户的DS-CDMA(Direct Sequence-Code Division Multiple Access)信号为研究对象,在深入分析直扩信号检测、参数估计、盲解扩算法和伪码序列估计基础上,提出了一套有效的多用户直扩信号盲估计系统,并且最终可以得到无误码的伪码序列估计。本文的贡献归纳起来包括以下几个方面:1.首先对多用户DS-CDMA信号盲估记系统进行了分析,提出了一个完整的直扩信号盲估计系统的设计方案。根据方案,依次进行各个系统模块的研究。2.对现有的单用户信号多种参数估计算法在多用户条件下进行了理论推导与性能检验。对DS-CDMA信号用户个数估计的信息论准则与特征值分析准则两种算法进行了计算机性能仿真,并在多用户非功率控制信号的情况下,对这两种算法的性能进行了比较分析。3.研究了DS-CDMA信号扩频序列估计的问题。使用EM算法实现了BPSK调制DS-CDMA信号的扩频序列波形估计,并且通过观测矩阵投影操作,降低了算法的计算复杂度。然后在此基础上,进一步推导实现了EM算法对QPSK调制DS-CDMA信号的扩频序列波形估计,最后通过仿真验证了算法的性能。4.研究了含误码序列重构的问题。由于通常的直扩信号盲估计系统获得的扩频序列估计并不是真实扩频序列的有效估计,往往含有一定的误码。本文通过对含误码序列重构技术的研究,对获得的扩频序列进一步估计重构,最终获得了不含有误码的真实扩频序列的准确估计,同时也完成了对扩频序列类型的识别(m序列或Gold序列)。5.最后在获得扩频序列准确估计的基础上,研究了利用了扩频序列的灵巧干扰与传统压制式干扰对直扩信号的干扰性能。
[Abstract]:DSSS signal transmission with a low probability of intercept, narrowband interference, multi-path and multi access etc., are widely used in military communication. In the non cooperative scenario of low SNR because of the multidimensional characteristic parameters of multi user signals and each user spreading sequences are different and are unknown. In this case, to achieve signal interception then further realize blind despreading is very difficult. At the same time, the existing blind estimation of spread spectrum sequence of the system often contains error estimation, and not the real sequence accurate estimation. DSSS signal blind estimation mainly involves signal detection, signal parameter estimation. Pseudo code Waveform Estimation and further the PN sequence error free reconstruction, the traditional research is mostly on single user direct spread signal estimation, and based on the multi user DS-CDMA (Direct Sequence- Code Division Multiple Access) signal as the research object, in depth analysis of parameter estimation of DSSS signal detection, blind despreading and PN sequence estimation algorithm based on the proposed a set of effective multiuser DSSS signal blind estimation system, and ultimately can be obtained without error to estimate the PN sequence. The main contributions of this dissertation it includes the following aspects: 1. firstly, multiuser DS-CDMA signal blind estimate system is analyzed, put forward a complete estimation of DSSS system design. According to the scheme,.2. in each module of the single user signal for a variety of existing parameter estimation algorithm is derived and the performance theory test in multi-user condition. To estimate the number of users of the DS-CDMA signal information criterion and eigenvalue analysis. Two algorithms are realized by computer simulation, and non reactive in multi users The rate control signal, the performance of these two algorithms are compared and analyzed.3. of DS-CDMA signal estimation problem. EM algorithm is used to realize the BPSK modulation waveform sequence estimation of DS-CDMA signals, and through the observation matrix projection operation, reduces the computational complexity of the algorithm. Then on the basis of this. The deduced sequence of QPSK waveform modulation DS-CDMA signal EM estimation algorithm, finally verified by simulation the performance of.4. algorithm is studied with the error sequence reconstruction problem. Because the effective estimation of DSSS signal blind estimation of the spread spectrum sequence system usually estimated is not real sequence, often contain some error. Based on the research of the reconstruction error containing sequences, the sequences obtained further estimated reconstruction, finally got the real expansion does not contain error The accurate estimation of frequency sequence, but also to complete the identification of sequence types (m sequence or Gold sequence) based.5. finally in obtaining accurate estimates of the spreading sequence, on the use of smart jamming sequence and traditional jamming interference in DSSS signal.

【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN914.42

【共引文献】