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: 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 communication method and a communication apparatus, to reduce TA error accumulation caused by an open-loop adjustment manner, reduce intersymbol interference of an uplink signal, and improve stability of a communication system. In the method, a terminal device receives and obtains first configuration information, where the first configuration information includes time domain information of a first transmission opportunity; the terminal device sends a first signal, where the first signal is used to determine TA information; the terminal device obtains the TA information; and the terminal device determines a TA between the terminal device and a network device based on the TA information, where the TA is used for data transmission after a time domain start location corresponding to the time domain information of the first transmission opportunity.

Abstract: A terminal apparatus is provided. The terminal apparatus obtains synchronization signal and physical broadcast channel (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. The first random access preamble is determined based on the cyclic shift and/or the order of symbols.

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: A communication method and apparatus are provided. The method includes: A terminal device obtains first information, where the first information is used for mobility management of ascending-orbit and descending-orbit cells, and the first information is related to a latitude location. The terminal device performs the mobility management based on the first information. According to the method, in a scenario of ascending-orbit and descending-orbit cells in a satellite network, mobility management does not need to be frequently performed with frequency switching of ascending and descending orbits. In this way, efficiency of the mobility management of the terminal device can be improved, and system signaling overheads can also be reduced.

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: This application provides example satellite communication methods and example apparatuses. One example method includes receiving, by a terminal device, first information sent by a satellite, where the first information indicates a first timing change rate range. The terminal device can then measure a downlink timing change rate to obtain a first downlink timing change rate. The terminal device can then determine a first uplink timing change rate based on the first downlink timing change rate and the first timing change rate range. The terminal device can then perform uplink communication with the satellite based on the first uplink timing change rate.

Abstract: Example signal transmission methods based on satellite communication and apparatus are described. One example method includes: obtaining, by a communication device, carrier attribute information corresponding to a target carrier used to transmit an orthogonal frequency division multiplexing (OFDM) symbol. The carrier attribute information of the target carrier includes subcarrier spacing. The communications device determines a cyclic prefix (CP) length of the OFDM symbol based on the carrier attribute information of the target carrier and a preset correspondence between carrier attribute information and the OFDM symbol. The CP is used to carry first data. The first data is data in the OFDM symbol.

Abstract: Example random access methods and apparatus are described. In one example, the network device obtains a first random access preamble length of a first terminal device and a second random access preamble length of a second terminal device. The network device determines a first random access parameter of the first terminal device and a second random access parameter of the second terminal device based on the first random access preamble length and the second random access preamble length. The network device sends the first random access parameter and the second random access parameter to the first terminal device and the second terminal device respectively.

Abstract: A communication method and apparatus are provided. The method includes: A terminal device receives a first synchronization broadcast block (SSB) from a network device, where the first SSB indicates that a current network is in a coverage enhancement mode; then, the terminal device determines a target resource of first system information based on the first SSB; and finally, the terminal device receives the first system information from the network device based on the target resource. In the method, transmission of a plurality of repeated SSBs can be supported in the network coverage enhancement mode, and a quantity of transmitted system information blocks 1 (SIB1s) can be reduced, to reduce system overheads.

Abstract: The disclosure provides transmission methods and apparatuses. One example includes sending control signaling to a terminal device, to indicate the terminal device to send a physical uplink shared channel (PUSCH) on a first frequency band; and receiving the PUSCH sent by the terminal device on the first frequency band. The first frequency band includes at least one guard subcarrier. A quantity of the at least one guard subcarrier is determined based on a Doppler frequency shift of a beam covering the terminal device. The first frequency band is located on a frequency band corresponding to the beam.

Abstract: The technology of this application relates to an information transmission method, an apparatus, and a system. The method includes user equipment receives first indication information sent by a first network device, where the first indication information includes a polarization method of a target cell, and the user equipment performs cell measurement on the target cell based on the polarization method of the target cell. According to the method, the user equipment can obtain the polarization method of the target cell before entering the target cell. In this way, when performing cell handover and reselection, the user equipment can enable, based on the polarization method of the target cell, only a port corresponding to the polarization method of the target cell, to receive a satellite signal, and perform cell measurement on the target cell, to complete cell handover and reselection procedures.

Abstract: A communication method and a communication apparatus. A terminal device obtains a first SSB. The terminal device sends a random access preamble corresponding to the first SSB. The random access preamble is carried at a first time domain position. The first time domain position is associated with a timing offset value. The timing offset value is determined based on a round-trip delay between the network device and a first position in an area covered by the network device.

Abstract: Embodiments of the application provide a method for rate matching in a wireless communication network. A device obtains K information bits and a target code length M of a polar code, determines, according to a minimum value of a set of values, a mother code length N, polar encodes the K information bits to obtain an encoded sequence of N bits, obtains a target sequence of M bits from the N bit encoded sequence, and outputs the M-bit target sequence.

Abstract: A first communication apparatus obtains first indication information in a first slot, where the first indication information indicates the first communication apparatus to switch from an uplink transmission bandwidth to a first transmission bandwidth; then, the first communication apparatus determines a second slot based on the first slot and a first switching delay, where the first switching delay is determined based on a first timing offset value, and the first timing offset value is determined based on a round-trip delay between a first location in an area covered by a second communication apparatus and the second communication apparatus; and the first communication apparatus sends uplink information to the second communication apparatus by using the first transmission bandwidth from the second slot.

Abstract: A first satellite obtains a parameter for determining an elevation angle for a departure service of the first satellite in a first serving cell. The first satellite sends first indication information to a terminal device, where the first indication information indicates the elevation angle for the departure service of the first satellite in the first serving cell in which the terminal device is located. The terminal device determines an elevation angle of the terminal device relative to the first satellite based on an ephemeris and location information of the terminal device. The terminal device determines the elevation angle for the departure service based on the first indication information, and compares the elevation angle for the departure service with the elevation angle of the terminal device relative to the first satellite, to determine whether to perform satellite reselection or handover.

Abstract: The disclosure provides beam indication methods and apparatuses One example method includes that a terminal device determines first random access information associated with a first synchronization broadcast block (SSB) and associated with a beam parameter of a satellite beam, where the beam parameter is used to distinguish the satellite beam. The terminal sends a preamble to a satellite based on the first random access information. The satellite receives the preamble from the terminal, and determines the first random access information. The satellite determines the first SSB and the beam parameter of the satellite beam that are associated with the first random access information.

Abstract: Communication methods and apparatus are provided. A communication method includes: A second communication apparatus determines second indication information, and sends the second indication information, wherein the second indication information indicates a polarization manner of a neighboring cell of a cell in which a first communication apparatus in an inactive state is located, and the polarization manner of the neighboring cell comprises one or more of left hand circular polarization, right hand circular polarization, linear polarization, or cross polarization multiplexing.

Abstract: A first communication device receives a first signal from a second communication device, where a first band used for communication between the first communication device and a third communication device overlaps a second band used for communication between the second communication device and a fourth communication device. The first communication device adjusts a start moment of a first transmission frame of the first communication device or an end moment of the first transmission frame based on the first signal.