Large Offset Environmental DS-CDMA Frequency Offset Estimation Algorithm

Asynchronous DS-CDMA communication mode has many advantages so that many communication systems make use of this communication mode. The nature of WCDMA mobile communication system is a kind of asynchronous DS-CDMA system. When the mobile user is in high-speed mobile state, WCDMA communication system lack effective frequency offset compensation technique, especially when mobile users need to launch random access request, frequency offset estimation for WCDMA system needs to be improved.This paper focuses on this problem. The paper first introduces the theory of radio channels, and then describes the WCDMA uplink random access channel reception theory, focusing on the uplink random access process and frame structure. With respect to offset estimation for WCDMA random access channel under large frequency offset environment, this paper focuses on several estimation algorithms. This paper analyzes the Doppler shift of the mechanism and its impact on the performance of the receiver, and then introduces the WCDMA uplink preset frequency offset compensation algorithm and energy interpolation algorithm. An analysis of the shortcomings of these two algorithms is then made. Then the joint estimation algorithm based on the existing channel parameters and frequency offset estimation algorithm is proposed for WCDMA uplink random access channel under large offset environment. And the principle of the algorithm is described and analyzed.Then, some parameters of the algorithm that affect the algorithm performance are simulated. The algorithm for algorithm performance decline when low-noise ratio or a larger number of users is encountered, has been improved in this paper. This paper also tests the estimation performance of improved algorithm and analysis the complexity of the algorithm.Finally, this paper discusses the implementation of the improved algorithm on a DSP platform. This paper starts from the basic steps of the algorithm, introduces the reason for choosing TMS320DM6437 and CCS5.5.0 development environment and then introduces the program flow of the improved algorithm. Finally, the performance of the algorithms is analyzed. From the test results, it is realized that, under large frequency offset environment, this algorithm still has a good estimation performance, so it can be conclude that the algorithm has a strong practical value.