Estimating velocity using diversity reception

Abstract

In mobile communication systems, the velocity of m e bile terminals is important for adequate handoff control and efficient dynamic channel assignment [l]. We can estimate the velocity of a mobile terminal in a Rayleigh fading channel, because it is proportional to the Doppler frequency. Diversity reception is the most common method of improving communication quality in faded channels, and since the switching rate of diversity branches is proportional to the Doppler frequency, the velocity is easily estimated. We derived a relationship between the switching rate of the branches Nss (times/s), and the Doppler frequency fD (Hz): as follows NBS N 1 . 3 f~ .We confirmed this relationship experimentally, and since our method is very simple and needs no additional equipment] it can easily be implemented in mobile terminals.

VEPSD: a novel velocity estimation algorithm for next-generation wireless systems

“…Wavelets are used in [3] for velocity estimation. Switching rate of diversity branches is used for the velocity estimation in [4], but it is shown in [5] that this method is sensitive to the fading scenarios. Hence, it is not practical.…”

Urban Propagation Modeling for Wireless Systems

“…Not surprisingly, the results of [41] show that the signal correlation between selection decision times must be low in order for this method to work. Furthermore, branches that have different average received power show a downward bias in the estimate of the maximum Doppler frequency since the branch with the highest average will be preferred, resulting in fewer branch switches.…”

“…The minimum antenna spacing also includes an implicit assumption about the scattering environment (Challenge #1). The scattering assumed by [41] is that of an isotropic scattering channel.…”

“…Furthermore, branches that have different average received power show a downward bias in the estimate of the maximum Doppler frequency since the branch with the highest average will be preferred, resulting in fewer branch switches. Doumi and Gardiner [22] recast the problem as an envelope level crossing rate problem with a random level to characterize the dependence of this method on both the environment and on received signal power, a dependence originally avoided by [41]. Using Rice's derivation [76] of the envelope level crossing rate, the expectation of the number of branch switches per second is taken over the distribution of a random crossing threshold.…”

Mobile speed estimation for TDMA-based hierarchical cellular systems

“…The maximum Doppler frequency cannot be easily determined due to different levels of energy at these frequencies. In [3], the diversity switching number is used to estimate mobile speed, but it is pointed out in [4] that this method is highly dependent on the fading distribution statistical properties (Rayleigh fading, Rician fading, etc. ), and since it is not easy to know the distribution in advance, this method is not very reliable in practice.…”