Terminal apparatus, and control method for performing handover having enhanced communication efficiency

A terminal apparatus comprising:

• a receiving unit configured to receive, from a currently connected base station apparatus, a setting of a radio resource control (RRC) layer for another base station apparatus that is a destination candidate for a handover by the terminal apparatus from the base station apparatus and to receive, from the base station apparatus, a physical downlink control channel (PDCCH) order instructing the terminal apparatus to transmit a random access preamble to the other base station apparatus without handover to the other base station apparatus being performed;
• a transmitting unit configured to transmit the random access preamble to the other base station apparatus according to the instruction;
• and
• a performing unit configured to perform handover to the other base station apparatus in a case where a command instructing for a handover to the other base station apparatus is received from the base station apparatus,
• wherein, in a case where a signal requesting for retransmission of the random access preamble is received from the base station apparatus, the transmitting unit retransmits the random access preamble, and in a case where a signal requesting for retransmission of the random access preamble is not received from the base station apparatus or the other base station apparatus, the transmitting unit does not retransmit the random access preamble.

A control method executed by a terminal apparatus comprising:

• receiving, from a currently connected base station apparatus, a setting of a radio resource control (RRC) layer for another base station apparatus that is a destination candidate for a handover by the terminal apparatus from the base station apparatus and receiving, from the base station apparatus, a physical downlink control channel (PDCCH) order instructing the terminal apparatus to transmit a random access preamble to the other base station apparatus without handover to the other base station apparatus being performed;
• transmitting the random access preamble to the other base station apparatus according to the instruction;
• and
• performing handover to the other base station apparatus in a case where a command instructing for a handover to the other base station apparatus is received from the base station apparatus,
• wherein in the transmitting, in a case where a signal requesting for retransmission of the random access preamble is received from the base station apparatus, the random access preamble is retransmitted, and in a case where a signal requesting for retransmission of the random access preamble is not received from the base station apparatus or the other base station apparatus, the random access preamble is not retransmitted.