The Research And Implement Of The Frequency Offset Estimation For HSPA+System

There are two reasons result in frequency offset in mobile communication, one is the frequency discrepancy between the base station and the mobile station, the other is the Doppler frequency shift. Frequency deviation will affect the quality of the received signal, if the deviation is too large, will result in interruption of communication. The frequency offset estimation block is used for easing the frequency offset and compensate it.This paper mainly studies the algorithm of differential phase detection based on SCH channel and the algorithm of maximum likelihood (ML) estimation based on quadratic interpolation, makes simulation and analysis. In view of the shortcomings of these two algorithms, the algorithm of joint detection scheme based on the CPICH channel is proposed, its simulation and analysis are done, too. After considering the advantages and disadvantages of these algorithms, we select the algorithm of maximum likelihood estimation based on quadratic interpolation as a preferred option for the achievement. In the implementation process, two improved methods—multiplies the dispreading factor and estimates the frequency offset repeatedly are proposed, simulations and analysis are done.Finally, the second improved method is implemented. In the module of frequency offset adjustment, two filtering algorithms is proposed, simulated, analyzed and implemented. According to the characteristics of the chip, the code is optimized, the final results of the implementation is tested and analyzed.The algorithm of maximum likelihood estimation based on quadratic interpolation eventually is realized in hardware, the system is running in good condition, and the equipment developed by our project team successfully passed the field test. The algorithm meets the needs of practical application.