Abstract: This application provides an example timing advance update method, an example terminal, and an example base station. One example method includes receiving, by a terminal, an updated timing advance TA value and a beam cell identity of a beam cell in which the terminal is located that are sent by a base station. The example method also includes obtaining, by the terminal, corresponding TA compensation information based on the beam cell identity. The example method further includes performing, by the terminal, TA compensation in a TA update period based on the updated TA value and the TA compensation information. The example method also includes sending, by the terminal, uplink data by using a TA value obtained after TA compensation is performed.

Abstract: This application provides a random access method and an apparatus. The method includes: receiving, by a terminal device, a broadcast signal; and sending, by the terminal device, a random access signal, where a preamble sequence in the random access signal includes K first symbols and Q second symbols, the first symbol and the second symbol are different from each other, K and Q are integers greater than or equal to 1, K+Q=NSEQ, and NSEQ is a quantity of symbols included in the preamble sequence.

Abstract: An uplink signal sending and receiving method includes that a first communication apparatus obtains a first timing advance (TA) change rate, and sends an uplink signal in a plurality of first time periods. There is a first time interval between the plurality of first time periods to compensate for a time synchronization drift. A length of the first time interval and a location of the first time interval between the plurality of first time periods are determined based on the first TA change rate, and the first TA change rate is a TA change rate in a communication process of the first communication apparatus.

Abstract: Example methods and apparatus for determining a timing advance are described. One example method includes obtaining ephemeris information of a satellite, where the ephemeris information includes coordinates of the satellite and an ephemeris error of the satellite. A timing advance is determined according to a preset rule based on the ephemeris information and location information of a terminal device, where the location information includes coordinates of the terminal device and a positioning error of the terminal device. The preset rule is determined by using a first horizontal distance, a first vertical distance, the ephemeris error, and the positioning error.

Abstract: A bandwidth part switching method, is applicable to a non-terrestrial network (NTN) to implement BWP switching based on multi-color frequency-division multiplexing. In the method, a terminal device may report, in a second BWP to a network device, an index of a first SSB whose signal quality is greater than or equal to a first threshold in one or more SSBs in a first BWP, and switch from the second BWP to a third BWP. The one or more SSBs correspond to at least one BWP other than the first BWP, and the third BWP is in the at least one BWP and corresponds to the first SSB. After receiving the index of the first SSB in the second BWP, the network device determines the third BWP, and performs service data transmission with the terminal device in the third BWP.

Abstract: Example frequency compensation methods and apparatus are described. One example method includes determining first information and sending the first information by a network device to a terminal device, where the first information indicates a frequency compensation manner of an uplink signal of the terminal device or the first information indicates a configuration parameter of the terminal device. The terminal device receives the first information, and determines, based on the first information, the frequency compensation manner to be used to send the uplink signal. The terminal device performs frequency compensation for the uplink signal based on the frequency compensation manner.

Abstract: This application provides example beam management methods, apparatus, and systems. In one example method, a terminal device can receive indication information from a network device. The terminal device can perform beam switching according to an arrangement order of transmission configuration indicator (TCI) states (TCI-states) in a second TCI list when the indication information is first indication information. Alternatively, the terminal device can perform beam switching according to a first TCI-state in a first TCI list when the indication information is second indication information, wherein the first TCI list comprises a plurality of TCI-states comprising the first TCI-state, and in the first TCI list, beams corresponding to TCI-states after the first TCI-state are to sequentially provide a service for the terminal device.

Abstract: Embodiments of this application relate to the field of communication technologies, and provide a timing offset parameter update method, a device, and a system, to help reduce signaling overheads when a terminal device updates a value of a timing offset parameter. The method includes: A terminal device obtains a timing advance adjustment variation corresponding to the terminal device, where the timing advance adjustment variation is a difference between a timing advance adjustment amount currently used by the terminal device and a timing advance adjustment amount used at a previous moment. The terminal device determines whether an absolute value of the timing advance adjustment variation is greater than or equal to a first threshold. If the absolute value is greater than or equal to the first threshold, the terminal device sends, to a network device, first indication information used to indicate an update regularity of a timing offset parameter.

Abstract: This application provides a satellite communication method and apparatus. A terminal obtains a level-1 broadcast signal from a satellite, where a beam status corresponding to the level-1 broadcast signal is an energy saving state, and the level-1 broadcast signal includes synchronization information. The terminal obtains a level-2 broadcast signal from the satellite, where a beam status corresponding to the level-2 broadcast signal is a broadband communication state. The terminal communicates with the satellite based on the level-2 broadcast signal.

Abstract: This application discloses random access methods and communication apparatuses, and relates to the field of communication technologies. In an example method, after determining a correspondence between scanning periods of different scanning areas within coverage of a synchronization signal block (SSB) beam and random access occasions (ROs), a second communication apparatus sends, through broadcasting, a first message including information about the correspondence. A first communication apparatus receives the first message, determines an RO based on a scanning area in which the first communication apparatus is located and the first message, and initiates random access.

Abstract: This application provides a communication method and apparatus and a computer-readable storage medium. The method includes: receiving one or more synchronization information blocks SSBs; determining, based on a first SSB and/or a second SSB, a network type corresponding to the one or more SSBs; and determining an access network based on the network type. According to technical solutions provided in this application, a network type of an access network can be accurately identified in a frequency sweep stage.

Abstract: The technology of this application relates to a random access method, applied to the communication field. The method includes a terminal device sends, to a network device, a first message used to establish a wireless connection, the terminal device receives, a connection response sent by the network device, where the connection response includes information about a first polarization parameter, and when accessing the network device based on the connection response, the terminal device determines, based on the information about the first polarization parameter included in the connection response, whether the terminal device is qualified to access the network device. A dimension, namely, a polarization parameter, is introduced into a random access procedure, so that a preamble capacity is increased, a problem that the network device cannot identify a colliding terminal device is alleviated, and efficiency of establishing a communication connection between the terminal device and the network device is improved.

Abstract: This application provides a method and an apparatus for updating a timing offset, and is particularly applicable to an NTN network such as satellite communication. The terminal side method includes: A terminal receives a timing offset difference ?Koffset, and updates a timing offset based on the ?Koffset to obtain an updated timing offset. The network side method includes: A network device determines a timing offset difference ?Koffset, and sends the ?Koffset to a terminal device, wherein the ?Koffset is used for the terminal device to update a timing offset.

Abstract: The present disclosure relates to random access preamble transmission methods, apparatuses, and storage mediums. In one example method, a terminal device determines, based on a target sub-coverage area to which the terminal device belongs in a preset coverage area of a network device, target random access preamble format information corresponding to the target sub-coverage area. Then, the terminal device sends, to the network device on a target time-frequency resource indicated by target random access preamble time-frequency resource information corresponding to the target random access preamble format information, a random access preamble corresponding to the target random access preamble format information.

Abstract: Example communication methods and apparatus are described. In one example method, a terminal receives a first information by using a serving beam, where the first information indicates a delay compensation parameter corresponding to a target beam. The target beam and the serving beam are different beams. The terminal determines, based on a full timing advance and the delay compensation parameter corresponding to the target beam, a differential timing advance corresponding to the target beam.

Abstract: The present disclosure relates to access methods and apparatuses. In one example method, a terminal device determines, based on whether a first frequency offset parameter is in a frequency offset parameter range, whether to access a first cell. If the first frequency offset parameter is in the frequency offset parameter range, a current location of the terminal device is not at an edge of the cell. Otherwise, the current location of the terminal device may be at the edge of the cell.

Abstract: The present disclosure relates to network switching methods and apparatuses. in one example method, a beam that currently provides a service for a terminal device is a first beam. The first beam is generated by a first network device. The first network device obtains user information of the terminal device, and obtains switching information based on the user information. After the first network device sends the switching information to the terminal device, the terminal device can perform beam switching based on the switching information.

Abstract: This application discloses a random access preamble configuration method applicable to a satellite network and a communication apparatus. In the method, a random access preamble location offset and duration of a PRACH occasion can be flexibly configured based on features of a satellite system. The method includes: A receiving apparatus receives first indication information, where the first indication information includes indication information used to identify the random access preamble location offset at the physical random access channel PRACH occasion. The receiving apparatus transmits a random preamble based on the first indication information, where the random preamble includes a sequence part and a guard time. Because a communication distance is relatively long and a transmission delay difference between users is relatively large in a satellite communication system, time domain resources occupied by the PRACH occasion can be minimized by using this method.

Abstract: This application discloses a beam establishment method. A terminal apparatus obtains synchronization signal and PBCH blocks SSBs in a plurality of beams; then determines a target beam in the plurality of beams based on an association relationship between an SSB index and a first random access preamble, where the first random access preamble is determined based on a cyclic shift and/or an order of symbols; and finally sends the random access preamble by using the target beam, to initiate a random access request. A communication device receives the first random access preamble in the random access request sent by the terminal apparatus, and then determines, based on the association relationship, the target beam accessed by the terminal apparatus. According to embodiments of this application, the first random access preamble is determined based on the cyclic shift and/or the order of symbols.

Abstract: The disclosure provides satellite communication methods and related devices. One example method includes that a device receives a first common timing advance (TA) parameter and a first common TA change amount calculation parameter, where the first common TA parameter is used to obtain a first common TA, and the first common TA change amount calculation parameter is used to update the first common TA to obtain an updated common TA. The device sends a random access preamble by using the updated common TA.