# US 2018/0324865 A1 · Method for transmitting and receiving message for random access in multi beam system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0324865 A1 - Document ID: US20180324865A1 - Status: Published application - Kind: A1 - Application number: 15/971,301 - Filed: 2018-05-04 - Published: 2018-11-08 - Earliest claimed: 2017-05-04 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Bing HUI; Il Gyu KIM; Junhyeong KIM; Gosan NOH; Hee Sang CHUNG; Sung Woo CHOI - Web page: https://patentgrep.com/patent/US20180324865A1 ## CPC - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04B 7/0617: {for beam forming} - H04B 7/06952: {Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping} - H04B 7/088: {using beam selection} - H04W 74/004: {in the uplink, i.e. towards network} - H04W 74/006: {in the downlink, i.e. towards the terminal} - H04W 74/0891: {for synchronized access} - 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) - H04B: TRANSMISSION ## Abstract A method for transmitting and receiving a message for a random access (RA) between user equipment (UE) and a base station in a multi beam system includes: transmitting a synchronization signal (SS) block including a synchronization signal by performing beam sweeping for a multi beam; receiving a message 1 of an RA procedure from the UE; determining an optimal transmission beam to be used to transmit a message 2 of the RA procedure based on information about an association mapping between the SS block and a physical random access channel (PRACH) which is used to transmit the message 1; and transmitting the message 2 by using the optimal transmission beam. ## Claims ### Claim 1 A method for transmitting and receiving a message for a random access (RA) with user equipment (UE) by a base station in a multi beam system, the method comprising: transmitting a synchronization signal (SS) block including a synchronization signal by performing beam sweeping for a multi beam; receiving a message 1 of an RA procedure from the UE; determining an optimal transmission beam to be used to transmit a message 2 of the RA procedure based on information about an association mapping between the SS block and a physical random access channel (PRACH) which is used to transmit the message 1; and transmitting the message 2 by using the optimal transmission beam. ### Claim 2 (depends on 1) The method of claim 1, wherein the receiving the message 1 comprises calibrating a reception beam of the base station after successfully receiving the message 1 by performing reception beam sweeping. ### Claim 3 (depends on 1) The method of claim 1, wherein the multi beam used to transmit the SS block and the optimal transmission beam are a wide transmission beam. ### Claim 4 (depends on 3) The method of claim 3, further comprising: transmitting a signal for a fine calibration of a transmitting beam to the UE; and receiving information, through a message 3 of the RA procedure, about the optimal transmission beam determined based on a measurement result of the signal for the fine calibration. ### Claim 5 (depends on 4) The method of claim 4, wherein the information about the optimal transmission beam is included in a payload added to the message 3 or is included a physical uplink shared channel (PUSCH). ### Claim 6 (depends on 1) The method of claim 1, wherein the SS block includes a time index indication corresponding to index information of the multi beam. ### Claim 7 (depends on 1) The method of claim 1, wherein the SS block is mapped 1:1 with the PRACH resource in the association mapping. ### Claim 8 (depends on 1) The method of claim 1, wherein the SS block is mapped with a plurality of PRACH resources in the association mapping, ### Claim 9 A method for transmitting and receiving a message for a random access (RA) with a base station by user equipment in a multi beam system, the method comprising: receiving a synchronization signal (SS) block including a synchronization signal from the multi beam of the base station; determining a physical random access channel (PRACH) resource through which a message 1 of a RA procedure is transmitted based on information about an association mapping between the SS block and the PRACH resource; and transmitting the message 1 to the base station by using the determined PRACH resource. ### Claim 10 (depends on 9) The method of claim 9, wherein the multi beam used to transmit the SS block is a wide transmission beam. ### Claim 11 (depends on 10) The method of claim 10, further comprising: receiving a signal for a fine calibration of a transmission beam of the base station from the base station; determining information about an optimal transmission beam of the base station based on a measurement result of the signal for the fine calibration; and transmitting the information about the optimal transmission beam through a message 3 of the RA procedure. ### Claim 12 (depends on 11) The method of claim 11, wherein the transmitting the information about the optimal transmission beam comprises transmitting the information about the optimal transmission beam by using a payload added to the message 3 or by using a physical uplink shared channel (PUSCH). ### Claim 13 (depends on 9) The method of claim 9, further comprising determining index information of a transmission beam of the base station based on a time index indication included in the SS block. ### Claim 14 (depends on 9) The method of claim 9, wherein the SS block is mapped 1:1 with the PRACH resource in the association mapping. ### Claim 15 (depends on 9) The method of claim 9, wherein the SS block is mapped with a plurality of PRACH resources in the association mapping. ### Claim 16 A method for transmitting and receiving a message for a random access (RA) with user equipment (UE) by a base station in a multi beam system, the method comprising: transmitting a synchronization signal (SS) block including a synchronization signal by performing beam sweeping for a multi beam; receiving a message 1 of an RA procedure from the UE; determining an optimal transmission beam to be used to transmit a message 2 of the RA procedure based on information about an association mapping between the SS block and a preamble index of a preamble included in the message 1; and transmitting the message 2 by using the optimal transmission beam. ### Claim 17 (depends on 16) The method of claim 16, wherein the preamble is transmitted through the same physical random access channel (PRACH) resource or different PRACH resource. ### Claim 18 (depends on 16) The method of claim 16, wherein the preamble is transmitted through all available physical random access channel (PRACH) resource. ### Claim 19 (depends on 16) The method of claim 16, wherein the preamble is an orthogonally coded preamble. ### Claim 20 (depends on 16) The method of claim 16, wherein the SS block is mapped with the preamble and physical random access channel (PRACH) resource, and the receiving of the message 1 comprises receiving the message 1 including the preamble through the PRACH resource.