# US 12,004,106 B2 · Sidelink synchronization update > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,106 B2 - Document ID: US12004106B2 - Status: Granted - Kind: B2 - Application number: 17/420,179 - Filed: 2020-01-10 - Published: 2022-05-19 - Granted: 2024-06-04 - Earliest claimed: 2019-01-11 - Assignees: Nokia Solutions and Networks Oy - Applicants: Nokia Solutions and Networks Oy - Inventors: Sami-Jukka Hakola; Jorma Johannes Kaikkonen; Jari Olavi Lindholm - Web page: https://patentgrep.com/patent/US12004106B2 ## CPC - H04W 56/0015: {one node acting as a reference for the others} - H04L 27/2657: {Carrier synchronisation} - H04W 56/0025: {synchronizing potentially movable access points} - H04W 92/18: between terminal devices - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The example and non-limiting embodiments relate generally to synchronization and, more particularly, to a sidelink synchronization procedure. Exemplified embodiments are provided that may include determining a new synchronization source by a source user equipment, where the source user equipment is configured to provide synchronization to at least one receiving user equipment with use of a sidelink. The exemplified embodiments may further include transmitting by the source user equipment to the at least one receiving user equipment an indication that the source user equipment will update from a current synchronization source to the new synchronization source. The exemplified embodiments may further include transmitting synchronization signals and control signals from the source user equipment to the at least one receiving user equipment using an updated reference frequency corresponding to use of the new synchronization source by the source user equipment. ## Claims ### Claim 1 A method comprising: transmitting, by a source user equipment, a first synchronization signal to at least one receiving user equipment with use of a sidelink, the first synchronization signal having a first frequency; transmitting, by the source user equipment to the at least one receiving user equipment, an indication of a second frequency; and transmitting, by the source user equipment to the at least one receiving user equipment, a second synchronization signal having the second frequency, wherein the method further incudes determining a frequency offset between the first frequency and the second frequency, wherein transmitting the indication of the second frequency comprises transmitting indication of the frequency offset from the apparatus to the at least one receiving user equipment, wherein the indication of the frequency offset indicates a frequency offset amount in frequency units with a granularity, and wherein indication of the frequency offset amount in frequency units with the granularity comprises one of the following: 1.5 kHz with 15 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus; or 3 kHz with 30 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus. ### Claim 2 (depends on 1) A method as in claim 1, further comprising transmitting, by the source user equipment to the at least one receiving user equipment, timing information regarding when the source user equipment will start using the second frequency. ### Claim 3 (depends on 2) A method as in claim 2, wherein the timing information is transmitted with the indication. ### Claim 4 An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: transmitting, by the apparatus, a first synchronization signal to at least one receiving user equipment with use of a sidelink, the first synchronization signal having a first frequency; causing transmitting, by the apparatus to the at least one receiving user equipment, an indication of a second frequency; and causing transmitting, by the apparatus to the at least one receiving user equipment, a second synchronization signal having the second frequency, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the apparatus at least to perform: determining a frequency offset between the first frequency and the second frequency; and wherein transmitting the indication of the second frequency comprises transmitting indication of the frequency offset from the apparatus to the at least one receiving user equipment, wherein the indication of the frequency offset indicates a frequency offset amount in frequency units with a granularity, and wherein indication of the frequency offset amount in frequency units with the granularity comprises one of the following: 1.5 kHz with 15 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus; or 3 kHz with 30 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus. ### Claim 5 (depends on 4) An apparatus as in claim 4, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the apparatus at least to perform: causing transmitting, by the apparatus to the at least one receiving user equipment, timing information regarding when the apparatus will start using the second frequency. ### Claim 6 (depends on 5) An apparatus as in claim 5, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the apparatus at least to perform: causing transmitting of the timing information with the indication. ### Claim 7 (depends on 1) A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising the method as claimed in claim 1. ### Claim 8 An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a source user equipment with use of a sidelink between the source user equipment and the apparatus, a first synchronization signal having a first frequency; receiving, by the apparatus from the source user equipment, an indication of a second frequency; and receiving, by the apparatus from the source user equipment, a second synchronization signal having the second frequency, wherein receiving the indication of the second frequency comprises receiving indication of a frequency offset from the apparatus to the at least one source user equipment, wherein the indication of the frequency offset indicates a frequency offset amount in frequency units with a granularity, and wherein indication of the frequency offset amount in frequency units with the granularity comprises one of the following: 1.5 kHz with 15 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus; or 3 kHz with 30 kHz subcarrier spacing applied for synchronization signals or control signaling or both synchronization signals and control signaling provided by the apparatus. ### Claim 9 (depends on 8) An apparatus as in claim 8, wherein receiving the indication of the second frequency comprises receiving frequency offset between the first frequency and the second frequency. ### Claim 10 (depends on 4) An apparatus as in claim 4, wherein the indication of the frequency offset indicates a frequency location of the second frequency. ### Claim 11 (depends on 10) An apparatus as in claim 10, wherein indication of the frequency location comprises one of the following: a radio frequency channel; or a synchronization raster location. ### Claim 12 (depends on 4) An apparatus as in claim 4, wherein the indication of the second frequency comprises information indicating applied numerology used for coming synchronization signal transmissions using the second synchronization signal.