# US 12,010,731 B2 · Method and apparatus for handling msga retransmissions during two step random access procedures in wireless communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,010,731 B2 - Document ID: US12010731B2 - Status: Granted - Kind: B2 - Application number: 18/345,195 - Filed: 2023-06-30 - Published: 2023-11-02 - Granted: 2024-06-11 - Earliest claimed: 2019-02-13 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Anil Agiwal; Jaehyuk Jang; Soenghun Kim; Mangesh Abhimanyu Ingale - Web page: https://patentgrep.com/patent/US12010731B2 ## CPC - H04W 28/0278: {using buffer status reports (dynamic wireless traffic scheduling definition H04W72/12)} - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04W 74/004: {in the uplink, i.e. towards network} - H04W 74/006: {in the downlink, i.e. towards the terminal} - H04W 74/0836: with 2-step access - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 74/0838: using contention-free random access [CFRA] - H04W 74/0841: {with collision treatment} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract The 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. ## Claims ### Claim 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 including an uplink grant; identifying a random access procedure is successfully completed, in case that the preamble is associated with a contention free random access; and transmitting, to the base station, the MAC PDU obtained from the buffer based on the uplink grant, wherein the MSG B is received by monitoring a window starting at a first physical downlink control channel (PDCCH) occasion, which is at least one symbol after an end of the PUSCH. ### Claim 2 (depends on 1) The method of claim 1, wherein the MAC PDU obtained from 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. ### Claim 3 (depends on 1) The method of claim 1, further comprising receiving, from the base station, information configuring a resource for the PUSCH, wherein the information configuring the resource for the PUSCH 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. ### Claim 4 (depends on 1) The method of claim 1, wherein the random access procedure is considered successfully completed, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A. ### Claim 5 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); 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), transmitting, to the terminal, an MSG B including an uplink grant; and receiving, from the terminal, the MAC PDU based on the uplink grant, wherein the received MAC PDU is obtained from a buffer of the terminal, wherein a random access procedure is identified to be successfully completed, in case that the preamble is associated with a contention free random access, and wherein a window for the MSG B starts at a first physical downlink control channel (PDCCH) occasion which is at least one symbol after an end of the PUSCH. ### Claim 6 (depends on 5) The method of claim 5, wherein the MAC PDU obtained from 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. ### Claim 7 (depends on 5) The method of claim 5, further comprising transmitting, to the terminal, information configuring a resource for the PUSCH, wherein the information configuring the resource for the PUSCH 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. ### Claim 8 (depends on 5) The method of claim 5, wherein the random access procedure is considered successfully completed, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A. ### Claim 9 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, via the transceiver, 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 including an uplink grant, identify a random access procedure is successfully completed, in case that the preamble is associated with a contention free random access, and transmit, to the base station, via the transceiver, the MAC PDU obtained from the buffer based on the uplink grant, wherein the MSG B is received by monitoring a window starting at a first physical downlink control channel (PDCCH) occasion, which is at least one symbol after a last symbol of the PUSCH. ### Claim 10 (depends on 9) The terminal of claim 9, wherein the MAC PDU obtained from 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. ### Claim 11 (depends on 9) The terminal of claim 9, wherein the controller is further configured to receive, from the base station, via the transceiver, information configuring a resource for the PUSCH, and wherein the information configuring the resource for the PUSCH 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. ### Claim 12 (depends on 9) The terminal of claim 9, wherein the random access procedure is considered successfully completed, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A. ### Claim 13 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), 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), transmit, to the terminal, via the transceiver, a MSG B including an uplink grant, and receive, from the terminal, via the transceiver, the MAC PDU based on the uplink grant, wherein the received MAC PDU is obtained from a buffer of the terminal, wherein a random access procedure is identified to be successfully completed, in case that the preamble is associated with a contention free random access, and wherein a window for the MSG B starts at a first physical downlink control channel (PDCCH) occasion which is at least one symbol after a last symbol of the PUSCH. ### Claim 14 (depends on 13) The base station of claim 13, wherein the MAC PDU obtained from 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. ### Claim 15 (depends on 13) The base station of claim 13, wherein the controller is further configured to transmit, to the terminal, via the transceiver, information configuring a resource for the PUSCH, and wherein the information configuring the resource for the PUSCH 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. ### Claim 16 (depends on 13) The base station of claim 13, wherein the random access procedure is considered successfully completed, in case that a random access preamble identifier (RAPID) included in the MSG B matches an index of the preamble for the MSG A.