First base station, second base station, and method

A second base station comprising:

• a memory storing instructions;
• and
• one or more processors configured to execute the instructions to:
• communicate with a terminal apparatus in accordance with a second radio access technology;
• receive an Application Protocol message including handover result information related to results of handovers from a first base station to other base stations, the first base station communicating in accordance with a first radio access technology;
• and
• perform, based on the handover result information, communication processing for a terminal apparatus performing a handover from the first base station to the second base station, wherein
• a RAN-INFORMATION RIM including the handover result information is set in the Application Protocol message for transmitting the Application Protocol message from the first base station to the second base station,
• the RAN-INFORMATION RIM is an information element for transparent notification to the second base station via a first core network node in the first radio access technology and a second core network node in the second radio access technology, and
• the handover result information includes information indicating a handover success rate of each of handover-target base stations, the handover success rate being determined based on whether a first handover failed to be completed and whether a second handover is needed again within a predetermined period after the first handover is completed.

A method comprising:

• obtaining handover result information related to results of handovers from a first base station to other base stations, the first base station communicating with a terminal apparatus in accordance with a first radio access technology;
• setting, in an Application Protocol message, a RAN-INFORMATION RIM container including the handover result information to transmit the Application Protocol message to a second base station communicating in accordance with a second radio access technology, and
• transmitting, when a terminal apparatus performs a handover from the first base station to the second base station, the Application protocol message including the handover result information to the second base station, wherein
• the RAN-INFORMATION RIM container is an information element for transparent notification to the second base station via a first core network node in the first radio access technology and a second core network node in the second radio access technology, and
• the handover result information includes information indicating a handover success rate of each of handover-target base stations, the handover success rate being determined based on whether a first handover failed to be completed and whether a second handover is needed again within a predetermined period after the first handover is completed.