Abstract: This invention relates to methods and systems for determining whether a reference point in a location system has changed used measurement residuals determined from an exchange of messages between reference points. In one embodiment a method of determining whether the location of a first one of a plurality of reference points used in a location system has changed is provided.

Abstract: This invention relates to methods and devices for detection of motion. Embodiments of the invention provide a method of detecting motion of an object using a wireless transceiver device, the method including the steps of: transmitting wireless signals from a transmitter element in the transceiver device, the signals being reflected by the object; receiving the signals reflected by the object in a receiver element in the transceiver device; estimating at least one channel characteristic from the reflected signals; applying a time and/or frequency domain analysis to the estimated channel characteristic; detecting any variation in the estimated channel characteristic over time; and detecting motion of the object based on the detected variation. A wireless transceiver device arranged to detect motion is also provided.

Abstract: This invention relates to methods and systems for determining whether a reference point in a location system has changed using the entropy of channel impulse responses. In one embodiment a method of determining whether the location of a first one of a plurality of reference points used in a location system has changed is provided. The reference points each have a known initial position and the method includes the steps of: estimating a channel impulse response of a wireless channel between the first reference point and a second of said plurality of reference points; determining the difference between the estimated channel impulse response and a previously-estimated channel impulse response of the wireless channel; estimating an entropy of the difference between the channel impulse responses; and determining, from said comparison, whether the location of the first reference point has changed.