# US 12,004,236 B2 · Random access procedures for satellite communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,236 B2 - Document ID: US12004236B2 - Status: Granted - Kind: B2 - Application number: 17/838,576 - Filed: 2022-06-13 - Published: 2023-06-08 - Granted: 2024-06-04 - Earliest claimed: 2018-08-10 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Xingqin Lin; Shiwei Gao; Helka-Liina Määttänen; Siva Muruganathan; Jonas Sedin; Hazhir Shokri Razaghi; Zhenhua Zou - Web page: https://patentgrep.com/patent/US12004236B2 ## CPC - H04B 7/1851: {Systems using a satellite or space-based relay (H04B7/18508, H04B7/18521 take precedence; providing specific services H04B7/18523 - H04B7/18576)} - H04W 74/0841: {with collision treatment} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 56/007: {Open loop measurement} - H04W 56/0075: {based on arrival time vs. expected arrival time} - H04W 76/11: Allocation or use of connection identifiers - H04B 7/1853: {Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service (for selecting H04W)} - H04W 84/06: Airborne or Satellite Networks (space-based or airborne stations H04B7/185) - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methods are disclosed for random access in a wireless communication system such as, e.g., a wireless communication system having a non-terrestrial (e.g., satellite-based) radio access network. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method performed by a wireless device for random access comprises performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station. The method further comprises transmitting a random access preamble using the open-loop timing advance estimate. In this manner, random access can be performed even in the presence of a long propagation delay such as that present in a satellite-based radio access network. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed. ## Claims ### Claim 1 A method performed by a wireless device for random access, the method comprising: performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station, wherein the open-loop timing advance estimate is based on a comparison of a first time when a downlink system sub-frame is received, and a second time that is an expected time based on system frame timing configuration received from the base station; and transmitting a random access preamble using the open-loop timing advance estimate. ### Claim 2 (depends on 1) The method of claim 1 further comprising: receiving, from the base station, a random access response comprising a timing advance value; and determining a timing advance for the uplink between the wireless device and the base station based on the timing advance value comprised in the random access response and the open-loop timing advance estimate. ### Claim 3 (depends on 2) The method of claim 2 wherein the random access response schedules resources for an uplink transmission from the wireless device, and the method further comprises: transmitting an uplink transmission to the base station using the scheduled resources and the determined timing advance, the uplink transmission comprising an identity of the wireless device and an indication of the open-loop timing advance estimate. ### Claim 4 (depends on 3) The method of claim 3 wherein the indication of the open-loop timing advance estimate is the open-loop timing advance estimate. ### Claim 5 (depends on 3) The method of claim 3 wherein the indication of the open-loop timing advance estimate is a differential value that equals a difference between the open-loop timing advance estimate and a predefined or preconfigured reference value. ### Claim 6 (depends on 1) The method of claim 1 wherein the random access preamble is a function of the open-loop timing advance estimate. ### Claim 7 (depends on 6) The method of claim 6 further comprising selecting the random access preamble from a subgroup of a plurality of possibly random access preambles, the subgroup being chosen based on the open-loop timing advance estimate. ### Claim 8 (depends on 6) The method of claim 6 wherein the random access preamble provides an indication of the open-loop timing advance estimate. ### Claim 9 (depends on 6) The method of claim 6 further comprising: receiving, from the base station, a random access response comprising a timing advance value; and determining a timing advance for the uplink between the wireless device and the base station based on the timing advance value comprised in the random access response and the open-loop timing advance estimate. ### Claim 10 (depends on 9) The method of claim 9 wherein the random access response schedules resources for an uplink transmission from the wireless device, and the method further comprises: transmitting an uplink transmission to the base station using the scheduled resources and the determined timing advance, the uplink transmission comprising an identity of the wireless device and information that, together with a random access preamble transmitted by the wireless device, provide an indication of the open-loop timing advance estimate. ### Claim 11 (depends on 1) The method of claim 1 wherein the base station is part of a satellite radio access network comprising a satellite and a gateway that communicatively couples the base station to the satellite. ### Claim 12 A method performed by a base station for enabling random access in a radio access network, the method comprising: detecting a random access preamble from a wireless device; transmitting a random access response comprising a timing advance value; and receiving, from the wireless device, an uplink transmission, the uplink transmission comprising an identity of the wireless device and an indication of an open-loop timing advance estimate utilized by the wireless device to transmit the random access preamble, wherein the open-loop timing advance estimate is based on a comparison of a first time when a downlink system sub-frame is received by the wireless device, and a second time that is an expected time based on system frame timing configuration received by the wireless device from the base station. ### Claim 13 (depends on 12) The method of claim 12 wherein the base station is part of a satellite radio access network comprising a satellite and a gateway that communicatively couples the base station to the satellite. ### Claim 14 A method performed by a base station for enabling random access in a radio access network, the method comprising: detecting a random access preamble from a wireless device, the random access preamble being a function of an open-loop timing advance estimate of the wireless device, wherein the open-loop timing advance estimate is based on a comparison of a first time when a downlink system sub-frame is received by the wireless device, and a second time that is an expected time based on system frame timing configuration received by the wireless device from the base station; and transmitting, to the wireless device, a random access response comprising a timing advance value. ### Claim 15 (depends on 14) The method of claim 14 wherein the random access preamble is from a subgroup of a plurality of possibly random access preambles, the subgroup being indicative of the open-loop timing advance estimate. ### Claim 16 (depends on 14) The method of claim 14 wherein the random access preamble provides an indication of the open-loop timing advance estimate. ### Claim 17 (depends on 14) The method of claim 14 further comprising: receiving, from the wireless device, an uplink transmission comprising an identity of the wireless device and information that, together with the random access preamble transmitted by the wireless device, provide an indication of the open-loop timing advance estimate. ### Claim 18 (depends on 14) The method of claim 14 wherein the base station is part of a satellite radio access network comprising a satellite and a gateway that communicatively couples the base station to the satellite.