Study And Simulation The Frequency Offset Estimation Algorithm In WCDMA

In mobile communication systems, signal modulation launch, channel transmission and reception demodulation process, the inevitable will introduce some interference, makes the useful signal affected. Offset is a phenomenon caused by these disturbances, in the WCDMA (Wideband Code Division Multiple Access) mobile communication systems, because of the received signal in the presence of frequency offset, resulting in the signal demodulation of the signal to noise ratio (SNR) to reduce serious will affect the reception performance of the system, which requires the system to estimate the frequency offset and compensation.This hot issue around this subject within the research, the article first introduced wireless channel theory and research, analysis of the small-scale fading effects of wireless signals. WCDMA system uplink dedicated channel R99 and the physical random access channel, was comprised of two-channel frame structure and slot formats, as well as the WCDMA system uplink introduction to the structure of RAKE receiver, frequency offset estimation module in the RAKE receiver in location and importance of the analysis.Then the maximum likelihood frequency offset estimation algorithm has been studied, and thus derive a frequency offset estimated value of the expression. For the WCDMA system is characterized by, respectively, studied the R99 uplink dedicated channel and a random access channel frequency offset estimation algorithm and implementation. In the random access channel, because the available data is relatively small, so use the default task of several frequencies deviation of the random access approach to the process leading to demodulation, and then interpolating the results of the task demodulation is estimated to be offset value. For the Professional channel offset required from time to time due to its dynamic, and so the dedicated channel on the frequency offset is estimated to receive to the phase rotation between successive symbols to estimate the frequency offset angle, the theoretical basis of the algorithm is the maximum likelihood estimate.Finally, in order to solve high-speed mobile environment, the offset issue, proposed to improve the algorithm, is given three kinds of high-speed mobile environment, the algorithm simulation results and with the agreement calls for the standard value for comparison, the simulation results are analyzed to illustrate Algorithm fully to solve three kinds of fast-moving scenes under the offset issue. Therefore, the article studies the frequency offset estimation algorithm for WCDMA systems and high-speed mobile scenarios improved algorithm has a strong practical value.