US Patent 7994982 Method and apparatus for bounded time delay estimation

A method and apparatus for estimating the position of a mobile device in a multi-path environment. In one example, the method includes receiving a plurality of reference signals from a corresponding plurality of reference devices, for each reference signal, calculating expected time delay boundaries, for each reference signal, estimating a range between the device and the corresponding reference device based on a measured time delay of the reference signal falling within calculated time delay boundaries to produce a plurality of range estimates, and filtering the plurality of range estimates to generate a composite estimate of the position of the device.