Method and apparatus for performing random access procedure for coverage enhancement

1 . A method of A method of a user equipment (UE) for performing a random access procedure for coverage enhancement, the method comprising:

determining, for a random access procedure, whether message 3 (Msg3) is to be transmitted with repetitions or without repetition;

determining to transmit a random access channel preamble (RACH Preamble) for repeated transmission of message 3 (Msg3) when Reference Signal Received Power (RSRP) of a received synchronization signal is smaller than a predetermined threshold and the Msg3 is to be transmitted with repetitions;

transmitting the random access channel preamble for the repeated transmission of the Msg3 through a Physical Random Access Channel (PRACH);

receiving a random access response (RAR) including uplink scheduling information for the repeated transmission of the Msg3; and

repeatedly transmitting the Msg3 based on the uplink scheduling information,

wherein a number of repetitions of the Msg3 is indicated by a combination of downlink control information and higher layer signaling, the downlink control information being configured in DCI format 00 having CRC scrambled with TC (Temporary Cell)-RNTI,

wherein the DCI format 0_0 indicates a redundancy version (RV) ID, and the RV ID is a value of 0 for first repetition of the Msg3,

wherein the random access channel preamble for the repeated transmission of the Msg3 is configured based on a different sequence that is separated from a sequence for not repeatedly transmitting the Msg3,

wherein the random access channel preamble for the repeated transmission of Msg3 is transmitted repeatedly within a predetermined period for informing the base station of the repeated transmission of Msg3, and

wherein, when the Msg3 is not transmitted with repetitions, the random access channel preamble is transmitted on a first PRACH occasion configured for non-repeated Msg3, and when the Msg3 is transmitted with repetitions, the random access channel preamble is transmitted on a second PRACH occasion that is different from the first PRACH occasion and configured exclusively for repeated transmission of Msg3, the second PRACH occasion not being used when Msg3 is transmitted without repetition.

2 . A method of a base station for performing a random access procedure for coverage enhancement, the method comprising:

receiving a random access channel preamble (RACH Preamble) for repeated transmission of message 3 (Msg3) through a Physical Random Access Channel (PRACH);

transmitting a random access response (RAR) including uplink scheduling information for the repeated transmission of the Msg3; and

repeatedly receiving the Msg3 based on the uplink scheduling information,

wherein a number of repetitions of the Msg3 is indicated by a combination of downlink control information and higher layer signaling, the downlink control information being configured in DCI format 00 having CRC scrambled with TC (Temporary Cell)-RNTI,

wherein the DCI format 0_0 indicates a redundancy version (RV) ID, and the RV ID is a value of 0 for first repetition of the Msg3, wherein the random access channel preamble for the repeated transmission of the Msg3 is transmitted by a user equipment (UE) when Reference Signal Received Power (RSRP) of a received synchronization signal is smaller than a predetermined threshold,

wherein the random access channel preamble for the repeated transmission of the Msg3 is configured based on a different sequence that is separated from a sequence for not repeatedly transmitting the Msg3,

wherein the random access channel preamble for the repeated transmission of Msg3 is received repeatedly within a predetermined period for informing the base station of the repeated transmission of Msg3, and

wherein, when the Msg3 is not transmitted with repetitions, the random access channel preamble is received on a first, typical PRACH occasion configured for non-repeated Msg3, and when the Msg3 is transmitted with repetitions, the random access channel preamble is received on a second PRACH occasion that is different from the first PRACH occasion and configured exclusively for repeated transmission of Msg3, the second PRACH occasion not being used when Msg3 is transmitted without repetition.

3 . A user equipment (UE) for performing a random access procedure for coverage enhancement, the user equipment comprising:

a transmitter configured to transmit a random access channel preamble (RACH Preamble) for repeated transmission of message 3 (Msg3) through a Physical Random Access Channel (PRACH);

a receiver configured to receive a random access response (RAR) including uplink scheduling information for the repeated transmission of the Msg3; and

a controller configured to control an operation of the transmitter and the receiver,

wherein the transmitter repeatedly transmits the Msg3 based on the uplink scheduling information,

wherein a number of repetitions of the Msg3 is indicated by a combination of downlink control information and higher layer signaling, the downlink control information being configured in DCI format 0_0 having CRC scrambled with TC (Temporary Cell)-RNTI,

wherein the DCI format 0_0 indicates a redundancy version (RV) ID, and the RV ID is a value of 0 for first repetition of the Msg3,

wherein the controller is configured to determine, for a random access procedure, whether Msg3 is to be transmitted with repetitions or without repetition;

wherein the controller determines to transmit the random access channel preamble for the repeated transmission of the Msg3 when Reference Signal Received Power (RSRP) of a received synchronization signal is smaller than a predetermined threshold,

wherein the random access channel preamble for the repeated transmission of the Msg3 is configured based on a different sequence that is separated from a sequence for not repeatedly transmitting the Msg3,

wherein the random access channel preamble for the repeated transmission of Msg3 is transmitted repeatedly within a predetermined period for informing the base station of the repeated transmission of Msg3, and

wherein, when the Msg3 is not transmitted with repetitions, the random access channel preamble is transmitted on a first PRACH occasion configured for non-repeated Msg3, and when the Msg3 is transmitted with repetitions, the random access channel preamble is transmitted on a second PRACH occasion that is different from the first PRACH occasion and configured exclusively for repeated transmission of Msg3, the second PRACH occasion not being used when Msg3 is transmitted without repetition.