# US 2017/0289870 A1 · System and Method for Supporting Synchronization in Sidelink Communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0289870 A1 - Document ID: US20170289870A1 - Status: Published application - Kind: A1 - Application number: 15/469,630 - Filed: 2017-03-27 - Published: 2017-10-05 - Earliest claimed: 2016-03-31 - Assignees: Futurewei Technologies, Inc. - Applicants: Futurewei Technologies, Inc. - Inventors: Bin Liu; Yu Cai; Yongbo Zeng; Jian Wang - Web page: https://patentgrep.com/patent/US20170289870A1 ## CPC - H04W 36/0077: {of access information of target access point} - H04W 36/0016: {Hand-off preparation specially adapted for end-to-end data sessions} - H04W 36/0061: {of neighbour cell information} - H04W 36/00692: {using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] (allocation of physical resources in CoMP or in CA H04L5/0035)} - H04W 36/0094: {Definition of hand-off measurement parameters} - H04W 36/385: {of the core network} - H04W 56/0015: {one node acting as a reference for the others} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method for providing synchronization information includes acquiring a first synchronization information from a synchronization source, and transmitting a second synchronization information derived from the first synchronization information when the UE experiences a coverage change. ## Claims ### Claim 1 A method for providing synchronization information, the method comprising: acquiring, by a user equipment (UE), a first synchronization information from a synchronization source; and transmitting, by the UE, a second synchronization information derived from the first synchronization information when the UE experiences a coverage change. ### Claim 2 (depends on 1) The method of claim 1, wherein the second synchronization information is transmitted for a specified time period after the UE transitions from an out of coverage (OOC) UE to an in coverage (IC) UE. ### Claim 3 (depends on 2) The method of claim 2, wherein the UE is the IC UE when the UE determines that the synchronization source meets at least one criterion, and wherein the UE is the OOC UE when the UE is unable to detect any synchronization source meeting the at least one criterion. ### Claim 4 (depends on 3) The method of claim 3, wherein the at least one criterion comprises measurements of signals from the synchronization source meeting a measurement threshold. ### Claim 5 (depends on 4) The method of claim 4, wherein the measurements comprise at least one of a carrier-to-noise ratio, a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a reliability of the signals. ### Claim 6 (depends on 1) The method of claim 1, wherein the second synchronization information is transmitted until the UE is a specified distance away from a location where the UE transitions from the OOC UE to the IC UE. ### Claim 7 (depends on 1) The method of claim 1, wherein the second synchronization information is transmitted when a difference between the first synchronization information and local synchronization information of the UE is greater than a timing difference threshold. ### Claim 8 (depends on 1) The method of claim 1, wherein the second synchronization information is transmitted when a difference between the first synchronization information and local synchronization information of the UE is greater than a timing difference threshold and when a quality of signals from the synchronization source exceeds a quality threshold. ### Claim 9 (depends on 1) The method of claim 1, wherein the synchronization source comprises at least one of a global navigation satellite system (GNSS), a GNSS-equivalent, an evolved NodeB (eNB), or a cell. ### Claim 10 (depends on 1) The method of claim 1, wherein the first synchronization information is acquired before the UE transitions from an IC UE to an OOC UE, and wherein the second synchronization information is transmitted after the UE transitions to the OOC UE. ### Claim 11 (depends on 10) The method of claim 10, wherein the second synchronization information is transmitted for a specified time period after the UE transitions to the OOC UE. ### Claim 12 (depends on 11) The method of claim 11, wherein the synchronization source has an associated priority, and wherein the second synchronization information is transmitted when the UE is unable to detect any other synchronization source with higher associated priority or a synchronization reference (SyncRef) UE. ### Claim 13 (depends on 10) The method of claim 10, wherein the second synchronization information is transmitted until the UE is a specified distance away from where the UE transitioned from the IC UE to the OOC UE. ### Claim 14 A method for providing synchronization information, the method comprising: acquiring, by a user equipment (UE), a first synchronization information from a synchronization source; and transmitting, by the UE, a second synchronization information derived from the first synchronization information, wherein the second synchronization information is transmitted when a quality of signals from the synchronization source meets a quality threshold. ### Claim 15 (depends on 14) The method of claim 14, wherein the quality of signals from the synchronization source is determined in accordance with at least one of a reference signal received power (RSRP) measurement, a carrier-to-noise ratio, a reference signal received quality (RSRQ) measurement, and a reliability of the synchronization source. ### Claim 16 A user equipment (UE) comprising: one or more processors; and a computer readable storage medium storing programming for execution by the one or more processors, the programming including instructions to configure the UE to: acquire a first synchronization information from a synchronization source, and transmit a second synchronization information derived from the first synchronization information when the UE experiences a coverage change. ### Claim 17 (depends on 16) The UE of claim 16, wherein the programming includes instructions to configure the UE to transmit the second synchronization information for a specified time period after the UE transitions from an out of coverage (OOC) UE to an in coverage (IC) UE. ### Claim 18 (depends on 16) The UE of claim 16, wherein the programming includes instructions to configure the UE to transmit the second synchronization information until the UE is a specified distance away from a location where the UE transitions from the OOC UE to the IC UE. ### Claim 19 (depends on 16) The UE of claim 16, wherein the programming includes instructions to configure the UE to transmit the second synchronization information when a difference between the first synchronization information and local synchronization information of the UE is greater than a timing difference threshold. ### Claim 20 (depends on 16) The UE of claim 16, wherein the programming includes instructions to configure the UE to transmit the second synchronization information when a quality of signals from the synchronization source meets a quality threshold. ### Claim 21 (depends on 16) The UE of claim 16, wherein the programming includes instructions to configure the UE to transmit the second synchronization information when a difference between the first synchronization information and local synchronization information of the UE is greater than a timing difference threshold and when a quality of signals from the synchronization source exceeds a quality threshold. ### Claim 22 (depends on 16) The UE of claim 16, wherein the first synchronization information is acquired before the UE transitions from an IC UE to an OOC UE, wherein the second synchronization information is transmitted after the UE transitions to the OOC UE, and wherein the programming includes instructions to configure the UE to transmit the second synchronization information for a specified time period after the UE transitions to the OOC UE. ### Claim 23 (depends on 16) The UE of claim 16, wherein the first synchronization information is acquired before the UE transitions from an IC UE to an OOC UE, and wherein the second synchronization information is transmitted after the UE transitions to the OOC UE, and wherein the synchronization source has an associated priority, and wherein the programming includes instructions to configure the UE to transmit the second synchronization information when the UE is unable detect any other synchronization source with higher associated priority or a synchronization reference (SyncRef) UE.