Research On The Technology Of Ds-cdma Signal Bling Estimation

The spread-spectrum communicaitons depends on its low probability of capture,inherent anti-interference character and well multiple access has been widely used in military communications. In the non-cooperative scenario, it is difficult to intercept and analysis DSSS signals with unknown spreading code sequence and other parameters.And the existing blind estimation system’s spread-spectrum sequences estimated often contains error chips, it’s not the accurate estimation of the true spread-spectrum sequence.The main content of DSSS signal estimation is: signal detection, signal parameter estimation, spread-spectrum code estimation and spread-spectrum sequence error free reconstruction. Traditional research always remained in the estimation of single user DSSS signal. This paper’s research is based on multi-user DS-CDMA signal model.After researched many parts of blind estimation technology, designed an effective non-cooperative DS-CDMA signal blind estimation system that could get the accurate estimation of the spread-spectrum sequence.The main contributions of this dissertation are as follows.1.Made a complete study of the DS-CDMA signal intercept and blind estimation,and designed a non-cooperative DS-CDMA signal blind estimation system. According to the plan, the research carried out in turn each module of the system.2.Based on the existing single user signal estimation algorithm extending to multi-user DS-CDMA signal. Simulation and comparison the information theory criterion and eigenvalue analysis criterion of DS-CDMA signals user number estimation.3.Using EM algorithm in BPSK modulation realized the waveform estimation of multi-user DS-CDMA signal. And through the observation matrix projection operation,reduce the computational complexity of the algorithm. Based on that, extending EM algorithm to the QPSK modulation Situation. Finally, the performance of the algorithm is verified by simulation.4.Research on containing error sequence’s estimation and reconstruction. Because the usually DSSS signal blind estimation system’s estimation of the spread-spectrum sequence often contains error chips, it’s not the accurate estimation of the truespread-spectrum sequence.In this paper, through the study of containing error sequence reconstruction technology, using to further estimate of spread-spectrum sequence, the accurate estimation of the spread-spectrum sequence. And also complete the identification of the spread-spectrum sequence types(m or Gold sequences).5.Based on accurate estimation of the spread-spectrum sequence, Researched the using spreading sequences’ s smart jamming and the traditional jamming’s performance on interference to the DSSS signal.