The Research On Space-Time Signal Processing Technology Of Wireless Communications

In the 3G mobile communication system, Multi-user detection (MUD) and the smart antenna array are key technologies, and have been a hot spot in telecom research field. Multiple Access Interference and ISI are the main sources of interference and may reduce system capability and performance seriously, In order to eliminate its influence essentially and improve system performance, we must use these key technologies.In recently years, the main research work may focus on how to present a high performance, low complexity algorithm. Based on the thorough analysis of the smart antenna theory and unlit-user detection, this paper introduces a space time detection scheme of embedding the smart antenna array into multi-user detection in CDMA mobile communication system. The main works of dissertion are as follows.First: The smart antenna array and the multi-user detection are analysed basically. At the beginning part of this thesis, the expression of the antenna array conceptually , the several vector optimization rule and adaptive algorithm of beamform are discussed and compared. The signal model and the performance estimate of multiuser detection are introduced. At last, the several algorithm of blind multiuser detection are analysed and compared. Second: Think to ocalization of the blind multi-user detection, The smart antenna is combined with multi-user detection. On theGauss White Noise signal channel, two space-time receivers are proposed, respectively. One is the space-time blind adaptive multi-user detection receiver requiring the direct-of-arrical(DOA) and signature waveform of the desired, the other is the blind space-time adaptive multiuser detection receiver requiring only signature waveform of the desired user. By MATLAB simulations, it is shown that the two space-time receivers can greatly resist MAI.Third: The structure characteristic of the received DS-CDMA signal is analyzed in the presence of multi-path slow fading effect case for wirless mobile communication. According to this characteristic, four data-selected schemes based on chip-matched filter are presented from the perspective of energy and structure of signal. And the impact of the being combined these schemes and the blind space-time multi-user detection receivers based on GSCLMS and Kalman arithmetic on multiple-access interference(MAI) and inter-symbol interference(ISI) is analyzed. Through simulation, the reasonable data-selected schemes is applicable for these algorithm on differ time-lag and the new data-selected schemes can reduce operation.The research shows that the performance and the low complexity algorithm are effectively realized with adopting the adaptive multiuser detection and the data-selected schemes put forword in this paper, and can avoid MAI and ISI basically.