本文關鍵詞：直擴信號盲估計技術研究　出處：《電子科技大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： DS-CDMA信號 多用戶 盲估計 EM算法 序列重構

【摘要】：直擴通信憑借其傳輸信號具有低截獲概率、抗窄帶干擾、抗多徑效應和多址復用等優(yōu)點,廣泛運用于軍事通信。在低信噪比的非合作場景下,由于多用戶信號的多維特征參數(shù)以及各個用戶的擴頻碼序列不同而且均為未知,因此在這種情況下,要實現(xiàn)信號的截獲然后進一步實現(xiàn)信號的盲解擴是非常困難的。同時現(xiàn)有盲估計系統(tǒng)獲得的擴頻序列估計常常含有誤碼,并不是真實擴頻序列的準確估計。直擴信號盲估計的內(nèi)容主要涉及信號檢測、信號參數(shù)估計、偽碼波形估計以及進一步的偽碼序列無誤碼重構,傳統(tǒng)的研究大多停留在單用戶直擴信號的估計,而本文以多用戶的DS-CDMA(Direct Sequence-Code Division Multiple Access)信號為研究對象,在深入分析直擴信號檢測、參數(shù)估計、盲解擴算法和偽碼序列估計基礎上,提出了一套有效的多用戶直擴信號盲估計系統(tǒng),并且最終可以得到無誤碼的偽碼序列估計。本文的貢獻歸納起來包括以下幾個方面:1.首先對多用戶DS-CDMA信號盲估記系統(tǒng)進行了分析,提出了一個完整的直擴信號盲估計系統(tǒng)的設計方案。根據(jù)方案,依次進行各個系統(tǒng)模塊的研究。2.對現(xiàn)有的單用戶信號多種參數(shù)估計算法在多用戶條件下進行了理論推導與性能檢驗。對DS-CDMA信號用戶個數(shù)估計的信息論準則與特征值分析準則兩種算法進行了計算機性能仿真,并在多用戶非功率控制信號的情況下,對這兩種算法的性能進行了比較分析。3.研究了DS-CDMA信號擴頻序列估計的問題。使用EM算法實現(xiàn)了BPSK調(diào)制DS-CDMA信號的擴頻序列波形估計,并且通過觀測矩陣投影操作,降低了算法的計算復雜度。然后在此基礎上,進一步推導實現(xiàn)了EM算法對QPSK調(diào)制DS-CDMA信號的擴頻序列波形估計,最后通過仿真驗證了算法的性能。4.研究了含誤碼序列重構的問題。由于通常的直擴信號盲估計系統(tǒng)獲得的擴頻序列估計并不是真實擴頻序列的有效估計,往往含有一定的誤碼。本文通過對含誤碼序列重構技術的研究,對獲得的擴頻序列進一步估計重構,最終獲得了不含有誤碼的真實擴頻序列的準確估計,同時也完成了對擴頻序列類型的識別(m序列或Gold序列)。5.最后在獲得擴頻序列準確估計的基礎上,研究了利用了擴頻序列的靈巧干擾與傳統(tǒng)壓制式干擾對直擴信號的干擾性能。
[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.

【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN914.42

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本文編號：1387182