# US 11,452,143 B2 · Apparatus and method of random access precedure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,452,143 B2 - Document ID: US11452143B2 - Status: Granted - Kind: B2 - Application number: 17/147,302 - Filed: 2021-01-12 - Published: 2021-07-15 - Granted: 2022-09-20 - Earliest claimed: 2020-01-14 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Anil Agiwal; Hyunjeong Kang - Web page: https://patentgrep.com/patent/US11452143B2 ## CPC - H04W 56/001: {Synchronization between nodes} - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 72/569: {of the traffic information} - H04W 74/0836: with 2-step access - H04W 74/0838: using contention-free random access [CFRA] - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A communication method and system for converging a fifth generation (5G) communication system for supporting higher data rates beyond a fourth generation (4G) system with a technology for Internet of things (IoT) are provided. The communication method and system may be applied to intelligent services based on the 5G communication technology and the 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. A method for performing a random access procedure in a wireless communication system is provided. ## Claims ### Claim 1 A method performed by a terminal of a random access procedure for a small data transmission, the method comprising: receiving, from a base station, at least one synchronization signal block (SSB); identifying at least one preamble associated with the at least one SSB based on first information on a number of preambles per SSB and second information on a starting index, for one of a 4-step random access procedure or a 2-step random access procedure for the small data transmission; selecting a preamble from the identified at least one preamble corresponding to an SSB selected from the at least one SSB; and transmitting, to a base station, the selected preamble in a physical random access channel (PRACH) occasion corresponding to the selected SSB. ### Claim 2 (depends on 1) The method of claim 1, further comprising: identifying the second information on the starting index for one of the 4-step random access procedure or the 2-step random access procedure for the small data transmission. ### Claim 3 (depends on 2) The method of claim 2, wherein identifying the second information on the starting index comprises at least one of: acquiring the second information based on a predetermined value for the 4-step random access procedure or the 2-step random access procedure for the small data transmission; acquiring the second information based on third information indicating the starting index for the 4-step random access procedure or the 2-step random access procedure for the small data transmission; acquiring the second information based on at least one of fourth information on a number of preambles per SSB for a normal 4-step random access procedure and fifth information on a number of preambles per SSB for a normal 2-step random access procedure; or in case that the random access procedure is the 2-step random access procedure for the small data transmission, acquiring the second information based on the fourth information, the fifth information and sixth information on the number of preambles per SSB for the 4-step random access procedure for the small data transmission. ### Claim 4 (depends on 3) The method of claim 3, wherein at least one of the first information, the third information, the fourth information, the fifth information and the sixth information is transmitted on a control message from the base station. ### Claim 5 (depends on 1) The method of claim 1, wherein, for identifying the at least one preamble, in case that a number of SSBs per PRACH occasion is less than 1, an index for the at least one preamble associated with the at least one SSB starts from S; and in case that the number of SSBs per PRACH occasion is greater than 1 or equal to 1, the index for the at least one preamble starts from S+n·Npreambletotal/Y, wherein S is the starting index, n is an index of the at least one SSB, Npreambletotal is a total number of preambles used for the random access procedure and Y is the number of SSB per PRACH occasion. ### Claim 6 A method performed by a base station of a random access procedure for a small data transmission, the method comprising: transmitting, to a terminal, at least one synchronization signal block (SSB); and receiving, from the terminal, a preamble for one of a 4-step random access procedure or a 2-step random access procedure for the small data transmission, in a physical random access channel (PRACH) occasion corresponding to an SSB among the at least one SSB, wherein at least one preamble associated with the at least one SSB is identified based on first information on a number of preambles per SSB and second information on a starting index for one of the 4-step random access procedure or the 2-step random access procedure for the small data transmission, and the preamble corresponding to the SSB is selected from the at least one preamble. ### Claim 7 (depends on 6) The method of claim 6, wherein the second information on the starting index is identified as: acquiring the second information based on a predetermined value for the 4-step random access procedure or the 2-step random access procedure for the small data transmission; acquiring the second information based on third information indicating the start index for the 4-step random access procedure or the 2-step random access procedure for the small data transmission; acquiring the second information based on at least one of fourth information on a number of preambles per SSB for a normal 4-step random access procedure and fifth information on a number of preambles per SSB for a normal 2-step random access procedure; or in case that the random access procedure is the 2-step random access procedure for the small data transmission, acquiring the second information based on the fourth information, the fifth information and sixth information on the number of preambles per SSB for the 4-step random access procedure for the small data transmission. ### Claim 8 (depends on 7) The method of claim 7, wherein at least one of the first information, the third information, the fourth information, the fifth information and the sixth information is transmitted on a control message to the terminal. ### Claim 9 (depends on 6) The method of claim 6, wherein, in case that a number of SSBs per PRACH occasion is less than 1, an index for the at least one preamble associated with the at least one SSB starts from S; and in case that the number of SSBs per PRACH occasion is greater than 1 or equal to 1, the index for the at least one preamble starts from S+n·Npreambletotal/Y, wherein S is the starting index, n is an index of the at least one SSB, Npreambletotal is a total number of preambles used for the random access procedure and Y is the number of SSB per PRACH occasion. ### Claim 10 A terminal of a random access procedure for a small data transmission, the terminal comprising: a transceiver; and a controller coupled with the transceiver and configured to control to: receive, from a base station, at least one synchronization signal block (SSB), identify at least one preamble associated with the at least one SSB based on first information on a number of preambles per SSB and second information on a starting index, for one of a 4-step random access procedure or a 2-step random access procedure for the small data transmission, selecting a preamble from the identified at least one preamble corresponding to an SSB selected from the at least one SSB, and transmit, to a base station, the selected preamble in a physical random access channel (PRACH) occasion corresponding to the selected SSB. ### Claim 11 (depends on 10) The terminal of claim 10, wherein the controller is further configured to control to: identify the second information on the starting index for one of the 4-step random access procedure or the 2-step random access procedure for the small data transmission. ### Claim 12 (depends on 11) The terminal of claim 11, wherein, for identifying the second information, the controller is configured to control to perform at least one of: acquiring the second information based on a predetermined value for the 4-step random access procedure or the 2-step random access procedure for the small data transmission, acquiring the second information based on third information indicating the start index for the 4-step random access procedure or the 2-step random access procedure for the small data transmission, acquiring the second information based on at least one of fourth information on a number of preambles per SSB for a normal 4-step random access procedure and fifth information on a number of preambles per SSB for a normal 2-step random access procedure, or in case that the random access procedure is the 2-step random access procedure for the small data transmission, acquiring the second information based on the fourth information, the fifth information and sixth information on the number of preambles per SSB for the 4-step random access procedure for the small data transmission. ### Claim 13 (depends on 12) The terminal of claim 12, wherein at least one of the first information, the third information, the fourth information, the fifth information and the sixth information is transmitted on a control message from the base station. ### Claim 14 (depends on 10) The terminal of claim 10, wherein, for identifying the at least one preamble, in case that a number of SSBs per PRACH occasion is less than 1, an index for the at least one preamble associated with the at least one SSB starts from S; and in case that the number of SSBs per PRACH occasion is greater than 1 or equal to 1, the index for the at least one preamble starts from S+n·Npreambletotal/Y, wherein S is the starting index, n is an index of the at least one SSB, Npreambletotal is a total number of preambles used for the random access procedure and Y is the number of SSB per PRACH occasion. ### Claim 15 A base station of a random access procedure for a small data transmission, the base station comprising: a transceiver; and a controller coupled with the transceiver and configured to control to: transmit, to a terminal, at least one synchronization signal block (SSB), and receive, from the terminal, a preamble for one of a 4-step random access procedure or a 2-step random access procedure for the small data transmission, in a physical random access channel (PRACH) occasion corresponding to an SSB among the at least one SSB, wherein at least one preamble associated with the at least one SSB is identified based on first information on a number of preambles per SSB and second information on a starting index for one of the 4-step random access procedure or the 2-step random access procedure for the small data transmission, and the preamble corresponding to the SSB is selected from the at least one preamble. ### Claim 16 (depends on 15) The base station of claim 15, wherein the second information on the starting index is identified as: acquiring the second information based on a predetermined value for the 4-step random access procedure or the 2-step random access procedure for the small data transmission, acquiring the second information based on third information indicating the start index for the 4-step random access procedure or the 2-step random access procedure for the small data transmission, acquiring the second information based on at least one of fourth information on a number of preambles per SSB for a normal 4-step random access procedure and fifth information on a number of preambles per SSB for a normal 2-step random access procedure, or in case that the random access procedure is the 2-step random access procedure for the small data transmission, acquiring the second information based on the fourth information, the fifth information and sixth information on the number of preambles per SSB for the 4-step random access procedure for the small data transmission. ### Claim 17 (depends on 16) The base station of claim 16, wherein at least one of the first information, the third information, the fourth information, the fifth information and the sixth information is transmitted on a control message to the terminal. ### Claim 18 (depends on 15) The base station of claim 15, wherein, in case that a number of SSBs per PRACH occasion is less than 1, an index for the at least one preamble associated with the at least one SSB starts from S; and in case that the number of SSBs per PRACH occasion is greater than 1 or equal to 1, the index for the at least one preamble starts from S+n·Npreambletotal/Y, wherein S is the starting index, n is an index of the at least one SSB, Npreambletotal is a total number of preambles used for the random access procedure and Y is the number of SSB per PRACH occasion.