Research On Mobile Speed Estimation In Wireless Cellular Systems

In wireless mobile communication channels with multi-path fading, performance of communication systems degrades significantly due to the signal envelope fluctuations. The mobile speed or, equivalently the maximum Doppler frequency, is of vital importance in the optimization of the whole performance of the system. The knowledge of the velocity of the mobile terminals is essential in adequate handoff control, efficient dynamic channel assignment, adaptive modulation, power control, equalization, etc. In recent years, many Doppler frequency estimation algorithms have been studied for the above wireless mobile applications. Most of these methods fall into two categories: based on the crossing rate and based on the covariance of the received signal. In this thesis, comparisons of some leading estimation methods are made. As a conclusion of this thesis, improvements were made in the method based on the logarithmic envelope. The simulation work is completed by the MATLAB tool.The simulation results prove that the improved method based on the logarithmic envelope performs obviously better than the original one. So, the scheme is feasible.