Abstract: A user apparatus for communicating with a first base station apparatus using a first RAT (Radio Access Technology) and a second base station apparatus using a second RAT includes a reception unit configured to receive, from the first base station apparatus, a configuration for measuring a timing difference between a cell of the first base station apparatus and a cell of the second base station apparatus; a control unit configured to perform measurement with respect to a cell of the second RAT based on the configuration for measuring the timing difference; and a transmission unit configured to transmit, to the first base station apparatus, a result of the performed measurement, wherein the configuration for measuring the timing difference includes information indicating an upper limit of a number of cells of the second RAT.

Abstract: A user apparatus communicates with a first base station apparatus and a second base station apparatus, and the user apparatus includes a receiving unit configured to receive, from the first base station apparatus, a configuration for measuring a timing difference between the first base station apparatus and the second base station apparatus; a control unit configured to execute measurement with respect to the second base station apparatus, based on the configuration for measuring the timing difference; and a transmitting unit configured to transmit a result of the executed measurement, to the first base station apparatus, wherein the executed measurement is executed before starting to communicate with the second base station apparatus.