Mobile Speed Estimation In Wireless Communication Systems

In wireless communication systems, mobile speed is very important information. It is essential for the control of resourse management, handover, and so on. From making use of it, receiver algorithms can be optimized from physical layer to upper protocol layer. The speed estimation in wireless communication systems is mainly studied in this paper.Fading statistics, including fading rate, level crossing rate, and average fade duration are always used for speed estimation, so these fading statistics are illustrated in this paper firstly. Then modeling and simulation of wireless channel is described, the model Jakes is used here. Then three typical methods for speed estimation, including level crossing rate, zero crossing rate and covariance function are presented, their performances are also analyzed and simulated.Based on the analysis of typical speed estimation algorithms, a method using the envelope of instantaneous channel coefficients is proposed, this method has defect in low signal-to-noise ratio, so an improved method that is based on the envelope of instantaneous channel coefficients is illustrated. In the improved method, Sampling is used in the receiver, and the sampling interval is enlarged, and then the bandwidth of the noise is decreased.On the condition of Nyquist Theorem,better speed estimation can be gained by using the improved algorithm. And also, properties of the improved algorithm and the classical algorithms are compared and simulated.The results of simulation shows this improved method has less calculation, has better performance of speed estimation and is robust to the noise.