# US 12,004,105 B2 · Time synchronization method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,105 B2 - Document ID: US12004105B2 - Status: Granted - Kind: B2 - Application number: 17/213,827 - Filed: 2021-03-26 - Published: 2021-07-15 - Granted: 2024-06-04 - Earliest claimed: 2018-09-28 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Yi Wang; Zhenyu Shi; Yingjie Yu - Web page: https://patentgrep.com/patent/US12004105B2 ## CPC - H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)} - H04W 56/0015: {one node acting as a reference for the others} - G01S 1/042: {Transmitters} - G01S 13/765: {with exchange of information between interrogator and responder} - H04J 3/0682: {by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 27/2675: {Pilot or known symbols} - H04W 56/001: {Synchronization between nodes} - H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management - G01S 5/10: Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements {, e.g. omega or decca systems}(G01S5/12 takes precedence {; beacons and receivers cooperating therewith G01S1/306, G01S1/308}) - H04L 5/008: {once only, on installation} - H04L 5/0091: {Signalling for the administration of the divided path, e.g. signalling of configuration information} - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract This application relates to the field of communications technologies, and provides a time synchronization method and an apparatus, to perform positioning and/or timing error measurement on a target terminal in a wireless communications system, so as to avoid a relatively large positioning error caused by a timing error between the target terminal and a base station. The method is used in a wireless positioning system, where the wireless positioning system includes a first node and a second node, and the method includes: The first node receives an arrival time t2 of a first reference signal and a sending time t3 of a second reference signal that are sent by a second node, where the first reference signal is sent by the first node, and the second reference signal is sent by the second node. ## Claims ### Claim 1 A time synchronization method in a wireless communications system, wherein the wireless communications system comprises a first node and a second node, and the method comprises: sending, by the first node, a first reference signal to the second node, and receiving an arrival time t2 at which the first reference signal arrives at the second node and that is sent by the second node; receiving, by the first node, a second reference signal and a sending time t3 at which the second reference signal is sent that are sent by the second node; and calculating, by the first node, a time of arrival (TOA) and a timing error Toffset based on the arrival time t2 of the first reference signal, the sending time t3 of the second reference signal, a sending time t1 at which the first node sends the first reference signal, and an arrival time t4 of the second reference signal received by the first node, wherein the time of arrival (TOA) comprises a difference between a time at which the second node sends a first signal and a time at which the first node receives the first signal sent by the second node, or a difference between a time at which the first node sends a second signal and a time at which the second node receives the second signal sent by the first node, the timing error Toffset comprises a frame error between the first node and the second node or a slot synchronization error between the first node and the second node, the first signal comprises the first reference signal, and the second signal comprises the second reference signal. ### Claim 2 (depends on 1) The method according to claim 1, wherein the time of arrival (TOA) is determined according to the following formula: TOA = ( t ⁢ 2 - t ⁢ 1 ) + ( t ⁢ 4 - t ⁢ 3 ) 2 , and the timing error Toffset is determined according to the following formula: T offset = ( t ⁢ 2 - t ⁢ 1 ) - ( t ⁢ 4 - t ⁢ 3 ) 2 . ### Claim 3 (depends on 1) The method according to claim 1, comprising: receiving, by the first node, the arrival time t2 of the first reference signal and the sending time t3 of the second reference signal through a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), a media access control control element (MAC CE), a radio resource control (RRC) message, or the long term evolution positioning protocol (LPP)/new radio positioning protocol (NRPP). ### Claim 4 (depends on 1) The method according to claim 1, wherein the first reference signal comprises at least one of the following: a positioning reference signal (PRS), a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), or a synchronization signal block (SSB); and the second reference signal comprises at least one of the following reference signals: a sounding reference signal (SRS) or a demodulation reference signal (DMRS). ### Claim 5 (depends on 4) The method according to claim 4, comprising: sending, by the first node, the timing error Toffset to the second node, wherein the timing error Toffset is used by the second node for timing compensation. ### Claim 6 (depends on 1) The method according to claim 1, wherein the first reference signal comprises at least one of the following: a sounding reference signal (SRS) or a demodulation reference signal (DMRS); and the second reference signal comprises at least one of the following reference signals: a positioning reference signal (PRS), a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), or a synchronization signal block (SSB). ### Claim 7 (depends on 6) The method according to claim 6, comprising: performing, by the first node, timing compensation on the first node based on the timing error Toffset. ### Claim 8 (depends on 1) The method according to claim 1, comprising: sending, by the first node, a time type indication to the second node, wherein the time type indication is used to indicate the second node to report an absolute time or a transition time. ### Claim 9 (depends on 1) The method according to claim 1, comprising: further obtaining, by the first node, a sum of radio frequency channel processing delays of the first node and the second node; calculating, by the first node, the time of arrival according to the following formula: TOA = ( t ⁢ 2 - t ⁢ 1 ) + ( t ⁢ 4 - t ⁢ 3 ) 2 - ( R b ⁢ s + R u ⁢ e ) ; and calculating, by the first node, the timing error according to the following formula: T offset = ( t ⁢ 2 - t ⁢ 1 ) - ( t ⁢ 4 - t ⁢ 3 ) 2 , wherein Rbs is a radio frequency channel processing delay of a base station, Rue is a radio frequency channel processing delay of a target terminal, the first node is the base station, and the second node is the target terminal. ### Claim 10 (depends on 1) The method according to claim 1, comprising: receiving, by the first node, a radio frequency channel processing delay sent by the second node, wherein the radio frequency channel processing delay is used by the first node for ranging calculation. ### Claim 11 A first node, comprising: a receiver, configured to receive an arrival time t2 of a first reference signal and a sending time t3 of a second reference signal that are sent by a second node, wherein the first reference signal is sent by the first node, and the second reference signal is sent by the second node; and a processor, configured to calculate a time of arrival (TOA) and a timing error Toffset based on the arrival time t2 of the first reference signal, the sending time t3 of the second reference signal, a time t1 at which the first node sends the first reference signal, and an arrival time t4 of the second reference signal received by the first node. ### Claim 12 (depends on 11) The first node according to claim 11, wherein the time of arrival (TOA) is determined according to the following formula: TOA = ( t ⁢ 2 - t ⁢ 1 ) + ( t ⁢ 4 - t ⁢ 3 ) 2 , and the timing error Toffset is determined according to the following formula: T offset = ( t ⁢ 2 - t ⁢ 1 ) - ( t ⁢ 4 - t ⁢ 3 ) 2 . ### Claim 13 (depends on 11) The first node according to claim 11, wherein the first node is configured to receive the arrival time t2 of the first reference signal and the sending time t3 of the second reference signal through a physical downlink shared channel (PDSCH), a media access control control element (MAC CE), or a radio resource control (RRC) message. ### Claim 14 (depends on 11) The first node according to claim 11, wherein the first reference signal comprises at least one of the following information: a positioning reference signal (PRS), a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), or a synchronization signal block (SSB); and the second reference signal comprises at least one of the following reference signals: a sounding reference signal (SRS) or a demodulation reference signal (DMRS). ### Claim 15 (depends on 14) The first node according to claim 14, further comprising: a transmitter, configured to send the timing error Toffset to the second node, wherein the timing error Toffset is used by the second node for timing compensation. ### Claim 16 (depends on 14) The first node according to claim 14, wherein the processor is further configured to perform timing compensation on the first node based on the timing error Toffset. ### Claim 17 (depends on 11) The first node according to claim 11, wherein the first reference signal comprises at least one of the following information: a sounding reference signal (SRS) or a demodulation reference signal (DMRS); and the second reference signal comprises at least one of the following reference signals: a positioning reference signal (PRS), a channel state information reference signal (CSI-RS), a phase tracking reference signal (PTRS), a demodulation reference signal (DMRS), or a synchronization signal block (SSB). ### Claim 18 (depends on 11) The first node according to claim 11, further comprising: a transmitter, configured to send a time type indication to the second node, wherein the time type indication is used to indicate the second node to report an absolute time or a transition time. ### Claim 19 (depends on 11) The first node according to claim 11, wherein the receiver is further configured to receive a radio frequency channel processing delay sent by the second node, wherein the radio frequency channel processing delay is used by the first node for ranging calculation. ### Claim 20 A non-transitory readable storage medium, wherein the non-transitory readable storage medium stores an instruction; and when the non-transitory readable storage medium runs on a device, the device is enabled to perform a time synchronization method, comprising: sending, by the first node, a first reference signal to the second node, and receiving an arrival time t2 at which the first reference signal arrives at the second node and that is sent by the second node; receiving, by the first node, a second reference signal and a sending time t3 at which the second reference signal is sent that are sent by the second node; and calculating, by the first node, a time of arrival (TOA) and a timing error Toffset based on the arrival time t2 of the first reference signal, the sending time t3 of the second reference signal, a sending time t1 at which the first node sends the first reference signal, and an arrival time t4 of the second reference signal received by the first node, wherein the time of arrival (TOA) comprises a difference between a time at which the second node sends a first signal and a time at which the first node receives the first signal sent by the second node, or a difference between a time at which the first node sends a second signal and a time at which the second node receives the second signal sent by the first node, the timing error Toffset comprises a frame error between the first node and the second node or a slot synchronization error between the first node and the second node, the first signal comprises the first reference signal, and the second signal comprises the second reference signal.