Radio terminal and base station

A radio terminal, comprising:

• a receiver configured to receive a sidelink signal for a relay in a proximity-based service from a second terminal;
• and
• a controller configured to determine whether the relay can be executed,
• wherein the controller determines that the relay can be executed when an identifier of a cell included in the sidelink signal indicates a predetermined cell in which the radio terminal is located.

A base station, comprising:

• a transmitter configured to transmit information of a determination criterion, the determination criterion defined by at least one of a reception level of a radio signal from the base station and a transmission level of the radio terminal, to a radio terminal configured to execute one of a first control, a second control, and a third control, wherein
• in the first control, the base station directly receives, from the radio terminal, uplink information to be transmitted to the base station, and directly transmits, to the radio terminal, downlink information to be received by the radio terminal,
• in the second control, the base station receives the uplink information from the radio terminal via a relay terminal configured to execute a relay using a proximity-based service, and directly transmits the downlink information to the radio terminal,
• in the third control, the base station receives the uplink information from the radio terminal via the relay terminal, and transmits the downlink information to the radio terminal via the relay terminal, and
• the determination criterion is used for determining an area in which the second control can be executed.

A radio terminal, comprising:

• a controller configured to execute one of a first control and a second control, wherein
• in the first control, the radio terminal directly transmits uplink information to be transmitted to a predetermined cell to the predetermined cell, and directly receives downlink information to be received by the radio terminal from the predetermined cell;
• in the second control, the radio terminal transmits the uplink information to the predetermined cell via a relay terminal configured to execute a relay using a proximity-based service, and directly receives the downlink information from the predetermined cell;
• and
• the controller executes the second control in preference to the first control.