Configuring multi-RAT early measurements

A wireless communication device for performing idle mode measurements in a cellular communications system, the wireless communication device comprising:

• one or more transmitters;
• one or more receivers;
• and
• processing circuitry configured to cause the wireless communication device to:
• receive system information from a first cell of a first network node;
• receive a dedicated release message from the first cell of the first network node, wherein the dedicated release message comprises:
• idle mode measurement configurations for one or more carriers for a first Radio Access Technology, RAT;
• idle mode measurement configurations for one or more carriers for a second RAT;
• or
• both idle mode measurement configurations for one or more carriers for the first RAT and idle mode measurement configurations for one or more carriers for the second RAT;
• determine idle mode measurement configurations to be applied by the wireless communication device while in the first cell based on the idle mode measurement configurations received on the first cell;
• apply the determined idle mode measurement configurations for idle mode measurements while in the first cell;
• perform idle mode measurements using the applied idle mode measurement configurations for idle mode measurements while in the first cell;
• perform a reselection to a second cell served by a second base station;
• receive system information from the second cell of a second network node, the system information received from the second cell comprising:
• idle mode measurement configurations for one or more carriers for the first RAT;
• idle mode measurement configurations for one or more carriers for the second RAT;
• or
• both idle mode measurement configurations for one or more carriers for the first RAT and idle mode measurement configurations for one or more carriers for the second RAT;
• determine idle mode measurement configurations to be applied by the wireless communication device while in the second cell based on:
• the idle mode measurement configurations comprised in the dedicated release message received from the first cell;
• and
• the idle mode measurement configurations comprised in the system information received from the second cell;
• apply the determined idle mode measurement configurations for idle mode measurements while in the second cell;
• and
• perform idle mode measurements using the applied idle mode measurement configurations for idle mode measurements while in the second cell,
• for each RAT from among the first RAT and the second RAT:
• determine whether the dedicated release message from the first cell comprises an idle mode measurement configuration for one or more carriers of the RAT;
• and
• upon determining that the dedicated release message from the first cell comprises an idle mode measurement configuration for one or more carriers of the RAT, apply the idle mode measurement configuration for the one or more carriers of the RAT comprised in the dedicated release message from the first cell,
• for each RAT from among the first RAT and the second RAT:
• upon determining that the dedicated release message from the first cell does not comprise an idle mode measurement configuration for one or more carriers of the RAT:
• determining whether the system information from the first cell comprises an idle mode measurement configuration for one or more carriers of the RAT;
• and
• upon determining that the system information from the first cell comprises an idle mode measurement configuration for one or more carriers of the RAT, applying the idle mode measurement configuration for the one or more carriers of the RAT comprised in the system information from the first cell.