Method and apparatus for handling MSGA retransmissions during two step random access procedures in wireless communication system
The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for the Internet of things (IoT). The present disclosure may be applied to intelligent services based on 5G communication technology and IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The present disclosure provides a method and apparatus for handling message A retransmission during 2 step random access procedures.
1. A method performed by a terminal in a wireless communication system, the method comprising:
storing a medium access control (MAC) protocol data unit (PDU) for a message (MSG) A in a buffer;
transmitting, to a base station, a preamble for the MSG A on a physical random access channel (PRACH);
transmitting, to the base station, the MAC PDU for the MSG A on a physical uplink shared channel (PUSCH);
receiving, from the base station, a MSG B indicating fallback; and
transmitting, to the base station, a MAC PDU identified based on the buffer, as a response to the MSG B,
wherein the MSG B is received by monitoring a window starting at a first physical downlink control channel (PDCCH) monitoring occasion, which is at least one symbol after a last symbol of the PUSCH.
2. The method of claim 1 , wherein the MAC PDU identified based on the buffer is transmitted, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A.
3. The method of claim 1 , further comprising receiving, from the base station, information configuring a resource for the PUSCH,
wherein the information includes at least one of information on a starting resource block (RB), information on a number of RBs, information on a number of frequency division multiplexed PUSCH occasions, information on a slot offset, or information on a length of symbols.
4. A method performed by a base station in a wireless communication system, the method comprising:
receiving, from a terminal, a preamble for a message (MSG) A on a physical random access channel (PRACH);
transmitting, to the terminal, a MSG B indicating fallback, in case that a medium access control (MAC) protocol data unit (PDU) for the MSG A is not received on a physical uplink shared channel (PUSCH); and
receiving, from the terminal, a MAC PDU as a response to the MSG B, wherein the received MAC PDU is identified based on a buffer of the terminal,
wherein a window for the MSG B starts at a first physical downlink control channel (PDCCH) monitoring occasion which is at least one symbol after a last symbol of the PUSCH.
5. The method of claim 4 , wherein the MAC PDU identified based on the buffer is received, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A.
6. The method of claim 4 , further comprising transmitting, to the terminal, information configuring a resource for the PUSCH,
wherein the information includes at least one of information on a starting resource block (RB), information on a number of RBs, information on a number of frequency division multiplexed PUSCH occasions, information on a slot offset, or information on a length of symbols.
7. A terminal in a wireless communication system, the terminal comprising:
a transceiver; and
a controller configured to:
store a medium access control (MAC) protocol data unit (PDU) for a message (MSG) A in a buffer,
transmit, to a base station, via the transceiver, a preamble for the MSG A on a physical random access channel (PRACH),
transmit, to the base station, the MAC PDU for the MSG A on a physical uplink shared channel (PUSCH),
receive, from the base station, via the transceiver, a MSG B indicating fallback, and
transmit, to the base station, via the transceiver, a MAC PDU identified based on the buffer, as a response to the MSG B,
wherein the MSG B is received by monitoring a window starting at a first physical downlink control channel (PDCCH) monitoring occasion, which is at least one symbol after a last symbol of the PUSCH.
8. The terminal of claim 7 , wherein the MAC PDU identified based on the buffer is transmitted, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A.
9. The terminal of claim 7 , wherein the controller is further configured to receive, from the base station, information configuring a resource for the PUSCH, and wherein the information includes at least one of information on a starting resource block (RB), information on a number of RBs, information on a number of frequency division multiplexed PUSCH occasions, information on a slot offset, or information on a length of symbols.
10. A base station in a wireless communication system, the base station comprising:
a transceiver; and
a controller configured to:
receive, from a terminal, via the transceiver, a preamble for a message (MSG) A on a physical random access channel (PRACH),
transmit, to the terminal, via the transceiver, a MSG B indicating fallback, in case that a medium access control (MAC) protocol data unit (PDU) for the MSG A is not received on a physical uplink shared channel (PUSCH), and
receive, from the terminal, via the transceiver, a MAC PDU as a response to the MSG B, wherein the received MAC PDU is identified based on a buffer of the terminal,
wherein a window for the MSG B starts at a first physical downlink control channel (PDCCH) monitoring occasion which is at least one symbol after a last symbol of the PUSCH.
11. The base station of claim 10 , wherein the MAC PDU identified based on the buffer is received, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A.
12. The base station of claim 10 , wherein the controller is further configured to transmit, to the terminal, information configuring a resource for the PUSCH, and
wherein the information includes at least one of information on a starting resource block (RB), information on a number of RBs, information on a number of frequency division multiplexed PUSCH occasions, information on a slot offset, or information on a length of symbols.