Patent ID: 8548471

Claim:
A user apparatus for use in a mobile communication system, comprising: a unit configured to receive a downlink control signal using a frequency of a residing cell; and a measurement unit configured to perform cell search using a frequency different from the frequency of the residing cell during an interval between reception timings of the downlink control signal in response to an occurrence of a predetermined event for different frequency measurement in the user apparatus or a base station apparatus, wherein the measurement unit does not perform different frequency measurement while receiving the downlink control signal, wherein, when a reception timing interval of the downlink control signal is longer than a threshold reported from the base station apparatus, the measurement unit performs different frequency measurement during the reception timing interval, wherein when the reception timing interval of the downlink control signal is not longer than the threshold, the measurement unit performs different frequency measurement during a discontinuous reception cycle that is longer than the reception timing interval and that is reported from the base station apparatus, and wherein, when the reception timing interval of the downlink control signal is shorter than the threshold reported from the base station apparatus, and when the predetermined event for different frequency measurement occurs in the user apparatus or in the base station apparatus, different frequency measurement is performed in a cycle reported from the base station apparatus; wherein it is determined by the base station apparatus that the predetermined event for the different frequency measurement occurs, and a measurement report for urging start of different frequency measurement is not transmitted to the base station apparatus.