Disclosed is a velocity estimator using a level crossing rate. The
velocity estimator comprises a power calculator for calculating power
values of a signal received from a mobile terminal; a mean power
calculator for calculating mean power values for M power values according
to a predetermined down-sampling factor M; an interpolator for
interpolating the mean power values according to a predetermined
interpolation ratio L; a root mean square calculator for calculating a
root mean square value using an output of the interpolator; a level
crossing counter for counting a level crossing frequency representing how
many times the output of the interpolator crosses a level crossing
threshold determined according to the root mean square value, for a
predetermined time period; and a velocity calculator for calculating a
velocity estimation value of the mobile terminal using the level crossing
frequency.