Provided is a method of determining timing of arrival of a signal on a path to a receiver in a mobile wireless communications system. The method comprises obtaining a channel impulse response (CIR) of a signal received at the receiver and deriving a power characteristic of the CIR. The method includes producing a first derivative of the power characteristic with respect to time, selecting some or all extrema from the first derivative of the power characteristic as indicative of candidate signal paths, and selecting one or more of said candidate signal paths. The method preferably includes determining timing of arrival of a signal on a first path of arrival at the receiver by assessing an energy value of each of said candidate signal paths against a threshold value.