Researches On Single-carrier Frequency Domain Equalization In Wcdma System

WCDMA is one of the Wireless Communication standards formulated by3GPP. Compared with the previous technology, it can not only provide a higher and faster transmission rates, but also inherited the second generation mobile communication technology GSM features:high degree of standardization and openness.The performance of the broadband wireless communication system is severally degraded due to the presence of the multipath fading interference, and the RAKE receiver is a technique to improve the performance of the broadband wireless communication system. However, with the number of paths in the multipath channel increasing, the frequency selective fading will become more and more serious, as well as the inter-symbol interference, for which it will be more difficult for the RAKE receiver to make accurate channel estimation so that the error performance of the broadband wireless communication system deceases.This thesis firstly introduces the frequency selective fading in the wireless channel which can influence the performance of the wireless communication system, for which the single carrier domain equalization is proposed, and then does some research on the principle of the single-carrier frequency domain equalization technique and system architecture. Based on LS (least square) channel estimation, some common linear equalization algorithms:zero forcing (ZF), minimum mean square error equalizer (MMSE), the maximum ratio combining (MRC) and equal gain equalizer (EGC) are achived in SC-FDE under SUI-3channel environment. The system simulation results indicate that single-carrier frequency domain equalization can effectively resist the wireless channel frequency selective fading, and get a good bit error rate (BER) performance.In this thesis the single-carrier frequency domain equalization is also applied to the DS-CDMA system, and the WCDMA system simulation platform is constructed based on3GPP25.213documents. The platform assumes signals are synchronized, and combined with the characteristics of the WCDMA downlink dedicated physical channel, using its pilots for channel estimation, and the calculate the equalizer coefficients to improve the WCDMA BER performance.Finally based on the existing algorithms the single-carrier frequency domain equalization in WCDMA system is developed in fixed-point DSP, and compared with the simulation results. According to the comparison the practical performance meets the system requirements regardless of the deviation.