Research And Implementation Of WCDMA Uplink Frequency Offset Estimation

In the high speed train scenario, the large offset of Doppler frequency shift existing in the WCDMA uplink has serious affects on the demodulation performance of the receiving system. How to realize accurate and real-time frequency offset estimation and compensation with high efficiency in high speed wireless communication is a hot issue in the mobile communication.Frequency offset estimation plays an important role in the coherent detection in burst mode transmission. Through a dynamic frequency offset estimation and compensation process, the frequency offset of the corrective baseband signal is fixed in a small range, and thus the demodulation in the baseband can be performed more accurately.Firstly, the thesis systematically introduces the evolution of WCDMA system and physical layer protocol. Secondly, the thesis discusses the wireless frame structure of special uplink, the random access channel, and the fundamental RAKE.The fundamental knowledge of frequency offset and the theoretical Cramer Rao low bound are also presented. Thirdly, frequency offset algorithm applied in random access channel and uplink dedicated channel are studied respectively. Then, based on the present random access frequency offset algorithm and combined with multipath power delay profile ratio and the interpolation function, an improved algorithm is researched; For the dedicated uplink, the autocorrelation function based on pilot symbols and depolarized non-pilot symbols is utilized. To optimize the frequency offset compensation, a novel compensation scheme is proposed in this thesis.Finally, the implement of the algorithm on DSP is discussed, along with the effect of the design of the related parameters. Then, based on the statistical data, the actual performance of the proposed algorithm is analyzed in detail. It shows that the optimized frequency offset algorithms have better performance than traditional methods.