US-12628051-B2 - Method for satellite handover between non-terrestrial networks, terminal device, and network device

US12628051B2US 12628051 B2US12628051 B2US 12628051B2US-12628051-B2

Abstract

The present application provides a method for satellite handover between non-terrestrial networks, a terminal device, and a network device. One example method includes: receiving a first handover command, where the first handover command instructs a terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network; and performing first synchronization with the second satellite network based on a first parameter before the satellite handover is performed, where the first parameter is determined based on information in the first handover command.

Inventors

Ling LYU
Zheng Zhao

Assignees

QUECTEL WIRELESS SOLUTIONS CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20250213

Claims (20)

1 . A method for satellite handover between non-terrestrial networks, comprising: receiving a first handover command, wherein the first handover command indicates a terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network, wherein the first handover command is a random access channel (RACH)-less handover command, handover indicated by the first handover command is first handover, and the terminal device supports backoff from the first handover to second handover, and the second handover is performed based on an RACH, wherein the first handover command comprises a pre-allocated grant scheduled by the second satellite network, a time domain location of an uplink resource, and time-related parameter of the second satellite network; and performing first synchronization with the second satellite network based on a first parameter before the satellite handover is performed, wherein the first parameter is determined based on information in the first handover command, wherein the first parameter including at least one of: a scheduling timing offset; or a round-trip time between a communications device and a reference point; transmitting, by the terminal device, data to the second satellite network according to a timing determined based on the first parameter or according to the pre-allocated grant, wherein the data is transmitted to the second satellite network by using a timing advance (TA) that is same as a TA used to transmit to the first satellite network; and performing the second handover to the second satellite network by using the RACH according to the backoff.
2 . The method according to claim 1 , wherein after the receiving the first handover command and before the satellite handover is performed, the method further comprises: determining a first scheduling offset based on the first parameter, wherein the first scheduling offset is used for the first synchronization.
3 . The method according to claim 2 , wherein the first scheduling offset is determined based on a second scheduling offset and a second parameter, wherein the second scheduling offset corresponds to the first satellite network; and the second parameter is a time difference caused by a distance between the first satellite network and the second satellite network.
4 . The method according to claim 3 , wherein the first scheduling offset is determined according to the following formula: K offset ⁢ 2 - temp = K offset ⁢ 1 + ( T ⁢ 2 - T ⁢ 1 ) , wherein K offset2-temp denotes the first scheduling offset; K offset1 denotes the second scheduling offset; T2 denotes a reference time when the terminal device is handed over from the first satellite network to the second satellite network; and T1 denotes a current reference time of the first satellite network.
5 . The method according to claim 1 , wherein the method further comprises: after the receiving the first handover command and before the satellite handover is performed, starting a first timer, wherein the first timer is configured to determine execution duration of the first synchronization.
6 . The method according to claim 1 , wherein the first synchronization is used to determine a third parameter used by the terminal device for the satellite handover; and the third parameter comprises one or more of the following parameters: a first time point when the terminal device performs the satellite handover; or a first time domain location at which the terminal device performs uplink transmission to the second satellite network during the satellite handover.
7 . The method according to claim 6 , wherein the third parameter is determined based on one or more of the following pieces of information: a first scheduling offset; a third scheduling offset corresponding to the second satellite network; a parameter of a first timer; or a first measurement result of measurement performed on the first satellite network by the terminal device.
8 . The method according to claim 7 , wherein the first measurement result indicates that the satellite handover is performed at a current instant; and the method further comprises at least one of the following: determining the first time domain location based on the third scheduling offset; determining the first time domain location based on the first scheduling offset and a difference between the first scheduling offset and the third scheduling offset; or determining the first time domain location based on the first scheduling offset.
9 . The method according to claim 8 , wherein the first time domain location is determined based on a second time domain location at which a TA command is received by the terminal device; and when the second time domain location is a slot n, the first scheduling offset K offset2-temp is less than the third scheduling offset K offset2 , and the first time domain location is a slot n+k+1+2 μ ·(K offset2-temp )+2 μ ·(K offset2 −K offset2-temp ); or the first scheduling offset K offset2-temp is greater than the third scheduling offset K offset2 , and the first time domain location is a slot n+k+1+2 μ ·(K offset2-temp ), wherein μ is determined based on subcarrier spacing; and k is determined based on transmission response duration and a quantity of slots, wherein k, n, and μ are integers.
10 . The method according to claim 7 , wherein the first measurement result indicates that the satellite handover is not performed at a current instant; and the first time point is determined based on the first timer.
11 . The method according to claim 1 , wherein the first parameter is determined based on at least one of: location information of the terminal device, configuration information of the second satellite network used for the satellite handover, or ephemeris information of a second satellite.
12 . The method according to claim 1 , further comprising: performing the second handover in response to that a quantity of failures of the first handover is greater than a first threshold.
13 . The method according to claim 1 , wherein the first synchronization comprises at least one of uplink synchronization or downlink synchronization.
14 . A method for satellite handover between non-terrestrial networks, comprising: transmitting a first handover command to a terminal device, wherein the first handover command instructs the terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network, wherein the first handover command is a random access channel (RACH)-less handover command, handover indicated by the first handover command is first handover, and the terminal device supports backoff from the first handover to second handover, and the second handover is performed based on an RACH, wherein the first handover command comprises a pre-allocated grant scheduled by the second satellite network, a time domain location of an uplink resource, and time-related parameter of the second satellite network, and wherein a timing advance (TA) used to transmit to the second satellite network is same as a TA used to transmit to the first satellite network; wherein the first handover command is used to determine a first parameter; and the first parameter is used by the terminal device for performing first synchronization with the second satellite network before the satellite handover is performed, wherein the first parameter including at least one of: a scheduling timing offset; or a round-trip time between a communications device and a reference point.
15 . An apparatus, comprising: at least one processor; and one or more non-transitory computer-readable storage media coupled to the at least one processor and storing programming instructions for execution by the at least one processor, wherein the programming instructions, when executed, cause the apparatus to perform operations comprising: receiving a first handover command, wherein the first handover command instructs a terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network, wherein the first handover command is a random access channel (RACH)-less handover command, handover indicated by the first handover command is first handover, and the terminal device supports backoff from the first handover to second handover, and the second handover is performed based on an RACH, wherein the first handover command comprises a pre-allocated grant scheduled by the second satellite network, a time domain location of an uplink resource, and time-related parameter of the second satellite network; and performing first synchronization with the second satellite network based on a first parameter before the satellite handover is performed, wherein the first parameter is determined based on information in the first handover command, wherein the first parameter including at least one of: a scheduling timing offset; or a round-trip time between a communications device and a reference point: transmitting data to the second satellite network according to a timing determined based on the first parameter or according to the pre-allocated grant, wherein the data is transmitted to the second satellite network by using a timing advance (TA) that is same as a TA used to transmit to the first satellite network; and performing the second handover to the second satellite network by using the RACH according to the backoff.
16 . The apparatus according to claim 15 , wherein after the receiving the first handover command and before the satellite handover is performed, the operations further comprise: determining a first scheduling offset based on the first parameter, wherein the first scheduling offset is used for the first synchronization.
17 . The apparatus according to claim 16 , wherein the first scheduling offset is determined based on a second scheduling offset and a second parameter, wherein the second scheduling offset corresponds to the first satellite network; and the second parameter is a time difference caused by a distance between the first satellite network and the second satellite network.
18 . The apparatus according to claim 17 , wherein the first scheduling offset is determined according to the following formula: K offset ⁢ 2 - temp = K offset ⁢ 1 + ( T ⁢ 2 - T ⁢ 1 ) , wherein K offset2-temp denotes the first scheduling offset; K offset1 denotes the second scheduling offset; T2 denotes a reference time when the terminal device is handed over from the first satellite network to the second satellite network; and T1 denotes a current reference time of the first satellite network.
19 . The apparatus according to claim 15 , wherein the operations further comprise: after the receiving the first handover command and before the satellite handover is performed, starting a first timer, wherein the first timer is configured to determine execution duration of the first synchronization.
20 . The apparatus according to claim 15 , wherein the first synchronization is used to determine a third parameter used by the terminal device for the satellite handover; and the third parameter comprises one or more of the following parameters: a first time point when the terminal device performs the satellite handover; or a first time domain location at which the terminal device performs uplink transmission to the second satellite network during the satellite handover.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2023/113814, filed on Aug. 18, 2023, the disclosures of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD The present application relates to the field of communications technologies, and more specifically, to a method for satellite handover between non-terrestrial networks, a terminal device, and a network device. BACKGROUND Random access channel-less (random access channel-less, RACH-less) handover is introduced, to improve user experience and shorten handover delay of a terminal device from a source cell to a target cell. However, a delay of propagation between a terminal device and a network device is relatively long in a non-terrestrial network (non-terrestrial network, NTN) system. When performing RACH-less satellite handover in an NTN system, a terminal device may be incapable of using an uplink resource configured by a target satellite network, resulting in handover access failure. SUMMARY The present application provides a method for satellite handover between non-terrestrial networks, a terminal device, and a network device. Various aspects of embodiments of the present application are described below. According to a first aspect, a method for satellite handover between non-terrestrial networks is provided, including: receiving a first handover command, where the first handover command is used to instruct a terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network; and performing first synchronization with the second satellite network based on first parameters before the satellite handover is performed, where at least some of the first parameters are determined based on information in the first handover command. According to a second aspect, a method for satellite handover between non-terrestrial networks is provided, including: transmitting a first handover command to a terminal device, where the first handover command is used to instruct the terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network; where the first handover command is used to determine at least some of first parameters; and the first parameter is used by the terminal device for performing first synchronization with the second satellite network before the satellite handover is performed. According to a third aspect, a method for satellite handover between non-terrestrial networks is provided, including: receiving a handover request transmitted by a first satellite network; and transmitting a handover response message to the first satellite network, where the handover response message is used by the first satellite network for determining a first handover command; the first handover command is used to instruct a terminal device to perform satellite handover from a coverage of the first satellite network to a coverage of a second satellite network; the first handover command is used to determine at least some of first parameters; and the first parameter is used by the terminal device for performing first synchronization with the second satellite network before the satellite handover is performed. According to a fourth aspect, a terminal device is provided. The terminal device includes: a receiving unit, receiving a first handover command, where the first handover command is used to instruct a terminal device to perform satellite handover from a coverage of a first satellite network to a coverage of a second satellite network; and an execution unit, performing first synchronization with the second satellite network based on first parameters before the satellite handover is performed, where at least some of the first parameters are determined based on information in the first handover command. According to a fifth aspect, a network device is provided. The network device corresponds to a first satellite network. The network device includes: a transmitting unit, transmitting a first handover command to a terminal device, where the first handover command is used to instruct the terminal device to perform satellite handover from a coverage of the first satellite network to a coverage of a second satellite network; the first handover command is used to determine at least some of first parameters; and the first parameter is used by the terminal device for performing first synchronization with the second satellite network before the satellite handover is performed. According to a sixth aspect, a network device is provided. The network device corresponds to a second satellite network. The network device includes: a receiving unit, receiving a handover request transmitted by a first satellite network; and a transmitting unit, transmitting a handover response message to the first satellite network, where the handover response message is used by the first sa