Patent ID: 6489923
Filing Date: 2002-12-03
Classification: G01S,H01Q

Abstract:
A method for estimating a bearing from an antenna situated at a cellsite to a mobile station in a radio telecommunications system, said antenna comprising a plurality of antenna elements for receiving signals transmitted by said mobile station, said received signals having a frequency including a frequency offset, being a Doppler frequency offset due to at least one of motion of said mobile station and a carrier frequency offset, and having a phase and an amplitude at each antenna element dependent on said bearing and on said frequency, comprising the steps of;(A): during each of a plurality of successive times obtaining a set of signal samples, by said signal received at each said antenna element dwell time shorter than said sampling time, such that not all of said received signals are sampled simultaneously; (B): estimating said phase and said amplitude of each said signal sample to obtain a corresponding complex phasor: (C): estimating said frequency offset using two or more of said phasors derived from signal samples successively received at one of said antenna elements; (D): said phasors corresponding to applying a phase-rotation compensation according to said estimate of said frequency offset to each of said antenna elements to obtain compensated phasors; and (E): estimating said bearing using a set of compensated phasors corresponding to at least one signal samples.