Abstract: A method for selecting a cell in a non-terrestrial network (NTN) The method includes: user equipment queries whether there is first prestored information and determines a frequency for preferential searching based on the first prestored information. The user equipment then determines values of a first decision factor, a second decision factor, a first weighting coefficient, and a second weighting coefficient in a first decision criterion. The user equipment searches for a cell according to the determined first decision criterion and selects a cell with the largest value of the first decision criterion is largest to camp.

Abstract: This application discloses a parameter determining method and apparatus. The method includes: after receiving first information, a terminal apparatus in a satellite communication system may determine a second parameter based on the first information and a first parameter, where the first information may indicate an association relationship between the first parameter and the second parameter; the first parameter is a parameter related to coverage of a first satellite, and the second parameter is a parameter related to coverage of a second satellite; and the first satellite is a satellite that provides a service for the terminal apparatus, and the second satellite is a satellite that is to provide a service for the terminal apparatus.

Abstract: Embodiments of this application disclose cell handover measurement indication methods, a network device, and a terminal, to improve reliability and real-time performance of cell handover. A cell handover measurement indication method includes: A network device calculates a measurement moment of cell handover based on a measurement event and sends a measurement indication. The measurement event is a location relationship between a terminal and the network device, and the measurement indication is used to indicate the terminal to perform cell handover measurement. The measurement indication sent by the network device may be used to notify the measurement moment of cell handover to the terminal.

Abstract: The disclosure includes a signal measurement method and a communication apparatus. A terminal obtains measurement configuration information, where the measurement configuration information includes information about at least one satellite cell and a measurement time range of the at least one satellite cell, the at least one satellite cell includes a first satellite cell, a measurement time range of the first satellite cell is all or a part of a time length in which a coverage area of the first satellite cell is in a first area, and the first area is an area in which the terminal is located. The terminal measures a signal of the at least one satellite cell in the first area based on the measurement configuration information, to obtain a metric, where the metric indicates a signal quality fluctuation of the at least one satellite cell in the measurement time range.

Abstract: An inter-satellite link construction method includes receiving, by a first satellite, an inter-satellite link creation message of a second satellite. The inter-satellite link creation message includes at least one of an address of the second satellite or a satellite number of the second satellite. The address of the second satellite is determined based on a projection location of the second satellite on a second ground projected track. The inter-satellite link construction method also includes, in response to the second satellite and the first satellite satisfying an inter-satellite link matching rule, creating, by the first satellite, an inter-satellite link between the first satellite and the second satellite. The inter-satellite link matching rule is determined based on at least one of the address of the second satellite or the satellite number of the second satellite.

Abstract: This application relates to the field of communication technologies. A first satellite obtains a destination address of a ground device, where the destination address is determined based on a ground projected track of a current access satellite of the ground device, the current access satellite is a satellite on a ground co-track satellite chain, and the ground co-track satellite chain includes a plurality of satellites that have a same ground projected track; and the first satellite sends data to the ground device based on a first satellite parameter and the destination address, where the first satellite parameter includes at least one of the following: an address of the first satellite, information about an inter-satellite link of the first satellite, and whether the first satellite directly communicates with the ground device.

Abstract: Satellite cell reselection control methods and related devices are provided. One satellite cell reselection control method includes: determining a current location status of the user equipment; determining a satellite cell reselection control parameter set corresponding to the current location status; and the performing satellite cell reselection control of the user equipment based on the obtained satellite cell reselection control parameter set.

Abstract: This application provides a data packet processing method and apparatus, applied to a satellite communications system. An earth surface, space, and network space are divided based on a satellite constellation and an ephemeris of a satellite, and an identifier is allocated to each ground area, each space area, and each network that are sub-divisions of the earth surface, space and network space, to establish a fixed mapping relationship between the EID, the SID, and the NID. In addition, each satellite maintains mapping relationship information recording the mapping relationship. Unless a satellite joins the constellation or one satellite leave service, the mapping relationship recorded in the mapping relationship information does not need to be updated. Based on the mapping relationship information, a satellite may route a data packet, thereby reducing a large amount of signaling interaction caused by establishing and maintaining a routing table in the conventional manner.

Abstract: This application provides a handover method and apparatus in satellite communications. The handover method in satellite communications in this application includes: obtaining, by a terminal device, ephemeris information of first satellite base stations, where the first satellite base stations are satellite base stations that cover the terminal device; determining, by the terminal device based on the ephemeris information, a destination satellite base station to which the terminal device needs to hand over; determining, by the terminal device based on the determined destination satellite base station, a first time at which the terminal device is to hand over to the destination satellite base station; and handing over, by the terminal device based on the determined first time, to a destination cell served by the destination satellite base station.

Abstract: Embodiments of this application disclose cell handover measurement indication methods, a network device, and a terminal, to improve reliability and real-time performance of cell handover. A cell handover measurement indication method includes: A network device calculates a measurement moment of cell handover based on a measurement event and sends a measurement indication. The measurement event is a location relationship between a terminal and the network device, and the measurement indication is used to indicate the terminal to perform cell handover measurement. The measurement indication sent by the network device may be used to notify the measurement moment of cell handover to the terminal.

Abstract: User equipment receives at least one TAC that is broadcast by a network device, where the TAC includes geographical location information, and the geographical location information is used to indicate a geographical location of a preset location point in a TA corresponding to the TAC. The user equipment determines, based on the TAC and a tracking area list (TAL), whether the TAL needs to be updated. If it is determined that the TAL needs to be updated, the user equipment sends a tracking area update request to the network device. The user equipment receives a response message, of the tracking area update request, returned by the network device.

Abstract: This application provides example communication methods, apparatuses, and systems. This application may be applied to the non-terrestrial communication network and the terminal device. The non-terrestrial communication network can include a cell set. The cell set can include a plurality of non-terrestrial transmission points, and the plurality of non-terrestrial transmission points have a same time-frequency resource. One example method includes sending information about the cell set, where the information about the cell set includes identification information of the cell set, resource configuration information of the cell set, and position information of at least one non-terrestrial transmission point in the plurality of non-terrestrial transmission points The cell set is used to communicate with the terminal device.

Abstract: Before a network jitter occurs, a server receives operation instructions from an electronic device, generates a plurality of first rendering instruction streams based on the operation instructions, sends the plurality of first rendering instruction streams to the electronic device, and generates and stores one or more first rendering contexts for one or more first rendering instruction streams in the plurality of first rendering instruction streams. When the network jitter occurs, the server generates a second rendering instruction stream based on received operation instructions, and generates and stores a second rendering context based on the second rendering instruction stream. After the recovery from the network jitter, the server sends a set of rendering context differences to the electronic device. In this way, network transmission traffic after the recovery from the network jitter is reduced, transmission and processing delays are also reduced, and user experience is improved.

Abstract: The present disclosure relates to communication methods and communication apparatuses. In one example method, a first communication apparatus receives first configuration information, where the first configuration information includes first identification update information and information about a first update moment of a first cell of a second communication apparatus, and the first identification update information is used to determine first identification information used by the first cell at the first update moment or after the first update moment. The first communication apparatus communicates based on the first configuration information by using the first identification information at the first update moment or after the first update moment, where the first communication apparatus is in a coverage range of the first cell.

Abstract: This application provides a handover method and apparatus in satellite communications. The handover method in satellite communications in this application includes: obtaining, by a terminal device, ephemeris information of first satellite base stations, where the first satellite base stations are satellite base stations that cover the terminal device; determining, by the terminal device based on the ephemeris information, a destination satellite base station to which the terminal device needs to hand over; determining, by the terminal device based on the determined destination satellite base station, a first time at which the terminal device is to hand over to the destination satellite base station; and handing over, by the terminal device based on the determined first time, to a destination cell served by the destination satellite base station.

Abstract: This application relates to communication methods and communication apparatuses. In an example method, a terminal device or a chip in the terminal device obtains first information. The first information is used to determine an access range corresponding to a first signal. In response to determining that the terminal device is located in the access range after a first moment, the terminal device or the chip in the terminal device sends a first random access preamble. The first random access preamble is associated with the first signal.

Abstract: Embodiments of this application disclose a communication method. The method includes: A terminal device sends a first message to a network device, where the first message includes one or more listening frequency indexes of one or more first tracking areas that are listened to by the terminal device within a first preset time period. The terminal device receives a second message including first registration area information from the network device. The first registration area information is determined based on the one or more listening frequency indexes. In the embodiments of this application, the accuracy of registration area information obtained by the terminal device can be improved, avoiding waste of communication resources caused by inaccurate registration area information received by the terminal device and improving communication resource utilization and practicality of the communication network.

Abstract: A handover method and apparatus are disclosed. In some implementations, the method includes: determining a part of terminal devices to be handed over in a plurality of terminal devices in a staring area of a first beam; sending a first handover request message to a target satellite, where the first handover request message includes contexts of the part of terminal devices; and receiving a handover instruction sent by the target satellite based on the first handover request message, and sending the handover instruction to the part of terminal devices by using the first beam. The handover instruction includes handover parameters used for handing over the part of terminal devices. According to some implementations, the part of terminal devices in the plurality of terminal devices in the staring area may be handed over, so that a signaling storm can be avoided and communication performance can be improved.

Abstract: In a cell handover method and apparatus, first network device of a first cell obtains user information of a terminal device, and then the first network device may determine handover information based on the user information and running information of the first network device, so that after the first network device sends an RRC message including the handover information to the terminal device, the terminal device may perform N consecutive cell handovers based on the handover information. In the N cell handovers, the first network device only needs to obtain the user information once, to configure handover conditions for the N subsequent handovers in advance at a time. This simplifies a network signaling procedure, reduces network overheads, and reduces handover response time. The embodiments of this disclosure are applicable to a network handover in a satellite scenario.

Abstract: Example communication methods and communication apparatus are described. One example method includes sending a first message by a first satellite to a second satellite. The first message includes information about a frequency reuse scheme. The information about the frequency reuse scheme includes basic unit information. The basic unit information includes central point locations and frequency information of at least N?1 beams. Herein, N is a frequency reuse factor of the first satellite. At least N?1 different pieces of frequency information exist in the frequency information that is of the at least N?1 beams and that is included in the basic unit information. In addition, N is a positive integer greater than or equal to 3.