A radio station (10) in which the value of parameters for a model of a
received
multipath signal are estimated, the model comprising a value representative of
the perpendicular distance between the plane of the reflecting surfaces (40,
50) and the radio station. This perpendicular distance may be measured from
the round trip delay of a sounding signal transmitted by the radio station. The
amount of computation is reduced by applying constraints to the parameters, and
these constraints may comprise this perpendicular distance. The constraints may
also be a function of parameters such as the path length, angle of arrival or amplitude
of the direct path signal, and the amplitude of reflections of the sounding signal.
The values of the parameters may be estimated initially by analysis of the received
signals, followed by a parameter estimation process. The values of the resulting
parameters are exploited in applications such as ranging, location or equalisation.
