Improvements relating to wireless networks

A method of determining a location of an apparatus relative to a previously determined location, the method comprising: detecting a change in motion of the apparatus by use of a sensor or sensors in the apparatus; determining a first estimate of the location of the apparatus at which said change of motion is detected, the first estimate of location being relative to the previously determined location, by use of at least one of said sensor or sensors; holding information relating to a plurality of reference points at which a change in motion is expected; determining that the detected change in motion relates to a first reference point of the plurality of reference points on a basis including the first estimate of the location and at least part of said information relating to the plurality of reference points; and re-setting the first estimate of location to a location of the first reference point.