Abstract: This application provides a communication method and a communications apparatus. A terminal in an inactive state receives a paging message, and content in the paging message is determined. When the content includes a first identity of the terminal, the terminal sends a first request message to a first access network device, where the first request message carries a non-access stratum (NAS) identifier of the terminal. When the content includes a second identity of the terminal and an identity of an anchor access network device, the terminal sends a second request message to the first access network device. The communication method of is application can adapt to a communication requirement of a terminal in an inactive state.

Abstract: Embodiments of this application disclose a message processing method and a device, and relate to the field of communication technologies. In this way, a network device can determine a DC location that is corresponding to communication when a plurality of BWPs are simultaneously activated. A specific solution is as follows: A network device receives a first message, where the first message includes a DC location of each of M bandwidth parts BWP that are configured by the network device for a terminal; and the network device determines a DC location of current communication based on DC locations of N activated BWPs in the M BWPs, where M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2 and less than M.

Abstract: This application provides a data processing method and apparatus, and a computer storage medium. When a PDCP entity over a UM DRB is re-established, or when a cell handover occurs and the PDCP entity over a UM DRB uses a key used before the handover, the PDCP entity determines a first SDU, where the first SDU is an SDU that is associated with a sequence number by the PDCP entity but whose corresponding data has not been transmitted through an air interface; and delivers a PDU corresponding to the first SDU to an RLC entity. Data corresponding to the first SDU is redelivered, to avoid a data packet loss caused by preprocessing of the PDCP entity.

Abstract: A connection resume request method includes generating, by a terminal, a new access stratum key; sending, by the terminal to a target base station, a connection resume request message requesting to resume a radio resource control (RRC) connection; receiving, by the terminal, a connection resume rejection message from the target base station, wherein the connection resume rejection message indicates that the resuming of the RRC connection is rejected; and resuming, by the terminal, the new access stratum key to a previous access stratum key, wherein the previous access stratum key is an access stratum key that is used, before the apparatus enters an inactive state, by the terminal and the source base station.

Abstract: A communications method and a communications apparatus. For a radio bearer that carries a multicast service, a downlink user plane tunnel is established between a first access network node and a second access network node. A data packet of the multicast service is transmitted through the downlink user plane tunnel to enable the multicast service to be transmitted in a CU-DU architecture. A unicast tunnel is also established to transmit a data packet of the multicast service that is sent in a unicast mode. In this way, the first access network node is able to transmit the data packet of the multicast service to the second access network node on the unicast tunnel in the unicast mode.

Abstract: In a key obtaining method and an apparatus, a first core network device obtains a first key, and the first core network device performs derivation based on the first key to obtain a second key and a third key. The second key is for performing security processing on control plane signaling of a terminal device, and the third key is for performing security processing on user plane data of the terminal device. The first core network device sends the second key to a control plane entity of a first access network device, and sends the third key to a user plane entity of the first access network device.

Abstract: This application provides a multicast information receiving method, an indication information sending/receiving method, and a related apparatus. The method includes: A first terminal apparatus receives first indication information from a network device; determines a first bandwidth of a first bandwidth part BWP based on the first indication information, where the first BWP is for receiving first multicast information, and the first bandwidth is a bandwidth configured in a master information block MIB or a system information block SIB1; and receives the first multicast information on the first bandwidth.

Abstract: A method and a device are provided. The method includes: selecting, by user equipment, a random access preamble from a random access preamble set, and selecting a random access channel resource from a random access channel resource set; sending, by the user equipment, the random access preamble by using the random access channel resource; and receiving, by the user equipment, a random access response message on a first downlink bandwidth part; wherein at least one of the random access preamble set or the random access channel resource set corresponds to the first downlink bandwidth part, and the random access channel resource includes at least one of a random access channel time domain resource or a random access channel frequency domain resource.

Abstract: A communication method includes determining, by a terminal device, that a second new data indicator (NDI) is toggled in response to a first condition being met. The second NDI is associated with a second resource. The method also includes receiving, by the terminal device, a second data. The second data is transmitted on the second resource. The second resource is associated with a second hybrid automatic repeat request (HARQ) process identifier (ID). The first condition includes the second resource is scheduled by using downlink control information (DCI) or physical downlink control channel (PDCCH) scrambled by a radio network temporary identifier (RNTI), among one or more other suitable conditions.

Abstract: Embodiments of the present disclosure disclose a mobility management method, user equipment, and a base station. The mobility management method may include: receiving, by user equipment UE in a connected mode, a source identifier of the UE from a first base station, where the source identifier is used to uniquely identify the UE in the first base station; entering, by the UE, a low-overhead state in the case that a low-overhead activation condition is satisfied, where in the low-overhead state, the UE stores a connection context of the UE in the connected mode, and camps on a cell according to a cell reselection criterion during movement; and reporting, by the UE when a first preset condition is satisfied, the source identifier to a second base station to which a second cell belongs, where the second cell is a serving cell on which the UE currently camps.

Abstract: This application provides for a data transmission method, an apparatus, and a device. The method may be applied to a relay communication system. The method includes a first network device that receives a first data packet. The first data packet is a data packet of a first multimedia broadcast multicast service (MBMS), and the first data packet carries first information. When second information of the first network device matches the first information, the first network device sends the first data packet to a terminal device that accesses the first network device. The second information is preconfigured for the first network device. In this way, the MBMS is transmitted in the relay communication system.

Abstract: This application provides a data transmission method and apparatus. The method includes: receiving downlink data, where the downlink data is used to be sent to a terminal device; receiving first information from a second network device, where the first information is used to determine a time point for sending the downlink data to the second network device; and sending the downlink data to the second network device based on the first information, to avoid directly sending the downlink data to the second network device after receiving the downlink data, thereby relieving storage burden of the second network device.

Abstract: This application discloses a multicast transmission method. The multicast transmission method includes: a first network device receives a first data packet and first indication information, where the first indication information indicates a sequence of the first data packet in at least one data packet; the first network device sets a sequence number of a first protocol layer of the first data packet based on the first indication information; and the first network device sends the first data packet to a terminal device. In this way, all data packets received by the terminal device include corresponding sequence numbers of the first protocol layers.

Abstract: A communication method and apparatus. A terminal device determines, based on first information received from a first network device, that a second network device has first time information, where the first time information is time information having precision that is higher than precision of second time information of the first network device. The terminal device obtains the first time information of the second network device based on the first information. The terminal device obtains high-precision time information to improve communication reliability.

Abstract: This application provides an RRC connection resume method and apparatus. In the method, when a terminal moves to a target base station, the target base station may reselect, based on a capability and a requirement of the target base station, a first encryption algorithm and a first integrity protection algorithm that are used when the target base station communicates with the terminal, and send the first encryption algorithm and the first integrity protection algorithm to the terminal. On one hand, a security algorithm used for communication between the terminal and the target base station is flexibly selected. On the other hand, because the base station connected to the terminal changes, communication security can be improved by using a new encryption algorithm and integrity protection algorithm.

Abstract: A method for determining cell quality information and an apparatus are provided. The method includes: A terminal device receives first information from a first network device, where the first information indicates that a first cell is associated with a first SSB and a second SSB, and frequency information of the first SSB is different from frequency information of the second SSB; and the terminal device determines quality information of the first cell based on a measurement value of the first SSB and a measurement value of the second SSB.

Abstract: A communication method, an access network device, a terminal device, and a core network device where the terminal device is handed over from a first access network device to a second access network device, the second access network device learns of first service progress of the first access network device based on a first sequence number of a data packet forwarded by the first access network device, without introducing additional progress exchange information between the two access network devices.

Abstract: A timer processing method includes: receiving, by a terminal device, a first message sent by a network device, and starting or restarting a timer based on a scrambling identifier of the first message, wherein the timer is a timer used by the terminal device to switch from an active downlink BWP to a default downlink BWP, or is a timer used by the terminal device to activate a default downlink BWP and deactivate an active downlink BWP; or if an active BWP pair of the terminal device is not a default BWP pair, starting or restarting, by the terminal device, a timer based on a scrambling identifier of the first message, wherein the timer is a timer used by the terminal device to switch from the active BWP pair to the default BWP pair, or is a timer used by the terminal device to activate the default BWP pair.

Abstract: Embodiments of this application provide a communication method and a device. The communication method and the device may be used in the field of a communication technology that supports a reduced capability terminal device, for example, weak-capability UE or MTC UE. The method includes: A first network device determines that a type of a first terminal device is a first type. The first network device sends a handover request message. The handover request message includes first indication information. The first indication information includes identifier information of the first type. The first network device receives a handover acknowledgment message or a handover preparation failure message.

Abstract: A communication method includes receiving a first message from a first network device, and sending a second message to a terminal device. The first message includes random access related information. The second message indicates a first random access type that is usable in a random access procedure. The first random access type is a 2-step random access channel (RACH) or a 4-step RACH. The random access related information includes at least one of random access indication information useable to indicate the first random access type, random access capability information including information of a random access type supported by the terminal device, random access mode information useable to indicate a contention-based random access mode or contention-free random access mode in the random access procedure, an early downlink-data transmission indication useable to indicate to transmit a downlink data packet in the random access procedure, or a size of the downlink data packet.