Abstract: This application provides a communication method and apparatus. The method includes: A terminal device receives indication information from a master node, where the indication information indicates that a key used for signaling transmission performed between the terminal device and a first secondary node by using a second SRB is a first key, the first key is a key used for signaling transmission performed between the terminal device and the master node by using a first SRB, and the first secondary node and the master node share one CU. In a scenario in which the master node and a secondary node share one CU, the terminal device determines that a key for signaling transmission performed between the terminal device and the secondary node is the same as a key for signaling transmission performed between the terminal device and the master node, which avoids complexity.

Abstract: Embodiments of this application provide a communication method and a communications system. The method includes: receiving, by a second network device from a first network device, information used to indicate that a terminal initiates a radio access network notification area update (RNAU), generating, by the second network device based on the information, a radio resource control release message on which security protection has been performed, and sending, to the first network device, the radio resource control release message on which the security protection has been performed.

Abstract: A communication method and a related device, the method including receiving a radio access capability of a terminal device, detecting whether a target radio access capability the same as the received radio access capability of the terminal device exists in a terminal device access capability set, where the terminal device access capability set is a set of radio access capability information corresponding to radio access capabilities, and, when the target radio access capability exists in the terminal device access capability set, indexing second access capability indication information in a context of the terminal device to radio access capability information corresponding to the target radio access capability.

Abstract: A data transmission method includes: receiving, by a user equipment (UE), first indication information from a wireless access device, where the first indication information is activation indication information or deactivation indication information; and when the first indication information is the activation indication information, executing, by the UE, a processing operation; or when the first indication information is the deactivation indication information, stopping, by the UE, the processing operation; where the processing operation includes at least one of a duplication operation and a switching operation; the duplication operation means transmitting same data through a plurality of links; and the switching operation means selecting one from a plurality of links to perform data transmission.

Abstract: In a method, a first band combination set reported by a terminal device may include a first band combination and a second band combination, the first band combination is a fallback band combination that has a same capability as the second band combination, and the first band combination and the second band combination correspond to different radio access technology types.

Abstract: The present disclosure relates to measurement methods and apparatus. In one example method, a terminal device receives N synchronization signal/physical broadcast channel block measurement timing configurations (SMTCs) from a network device. The terminal device obtains M measurement gaps based on M SMTCs in the N SMTCs respectively, where N and M are positive integers, and M is less than or equal to N.

Abstract: A history information recording method, including obtaining, by a current secondary node, information about a history cell that a terminal device visits, where the information about the history cell comprises at least one of stay time of the terminal device in the history or moving speed information of the terminal device in the history cell, and performing, by the current secondary node, handover preparation based on the information about the history cell.

Abstract: A method and an apparatus for transmitting a timing difference. The method includes obtaining, by a master node, a measurement value of a timing difference between a first cell and a second cell, and sending, by the master node, the measurement value of the timing difference and identification information of the second cell to a secondary node, where the first cell is a primary cell corresponding to the master node, the second cell includes a primary secondary cell corresponding to the secondary node or another cell different from the primary secondary cell, and the identification information of the second cell includes a physical cell identifier (PCI) and frequency information of the second cell.

Abstract: A communication method and apparatus, the method including obtaining, by a master access network device, handover triggering condition information of one or more cells corresponding to at least one candidate secondary access network device, sending a first message to a terminal device, where the first message comprises the handover triggering condition information, and receiving a first response message from the terminal device, where the first response message is used to indicate a cell identifier of a second cell corresponding to a second secondary access network device in the at least one candidate secondary access network device, and the second cell meets a handover triggering condition indicated by handover triggering condition information of the second cell.

Abstract: Example cell measurement methods and apparatus are described. One example method includes obtaining, by a first network device, a first paging parameter of a cell served by a second network device. The first paging parameter is used to indicate a first time domain position at which a terminal device monitors a paging message from the second network device. The first network device sends a reference signal based on the first paging parameter. A time domain position of the reference signal is determined based on the first time domain position.

Abstract: Embodiments of this application provide a synchronization signal/physical broadcast channel block (SSB) measurement method and an apparatus. One example method includes that a terminal device receives first information and second information. The first information indicates a time domain position of an SSB sent by a serving cell, and the second information indicates a set of SSBs that the terminal device needs to measure and that are sent by a neighboring cell. The terminal device measures, in a first measurement window based on the first information, the SSB sent by the serving cell. The terminal device measures, in a second measurement window based on the second information, the SSB sent by the neighboring cell.

Abstract: A handover method includes obtaining, by a source base station and a target base station, first indication information. The first indication information indicates a time during which a terminal device separately transmits data with the source base station and the target base station when the terminal device is handed over from a first cell of the source base station to a second cell of the target base station. The first cell and the second cell are intra-frequency neighboring cells. The method also includes sending, by the source base station, the first indication information to the terminal device.

Abstract: A communication method and apparatus, to help improve efficiency of identifying a fake base station. The method includes: A terminal device receives configuration information sent by a network device, and then simultaneously measures, based on the configuration information, a channel state information-reference signal CSI-RS and a synchronization signal block SSB that are sent by a cell. When determining that a measurement result of the CSI-RS and a measurement result of the SSB of the cell satisfy a preset condition, the terminal device reports a measurement report to the network device, where the measurement report includes identification information of the cell, so that the network device identifies a fake base station.

Abstract: Example communication methods and apparatus are described. One example method includes determining, by a terminal device, that a connection failure occurs between the terminal device and a first cell, where the first cell is a cell of a first network device. The terminal device determines signal quality of a second cell of a second network device, where both the first network device and the second network device provide communication services for the terminal device. If the signal quality of the second cell is greater than or equal to a first preset threshold, the terminal device performs a connection recovery process between the terminal device and the first cell by using the second cell.

Abstract: Example communication methods and apparatus are described. One example communication method includes receiving broadcast information by a terminal device. The broadcast information includes a first parameter and a second parameter that are for a first cell. The first parameter is used for cell selection or cell reselection performed by a terminal device that supports supplementary uplink (SUL) carrier transmission, and the second parameter is used for cell selection or cell reselection performed by a terminal device that does not support SUL carrier transmission. The terminal device performs cell selection or cell reselection based on the first parameter when the terminal device supports SUL carrier transmission. The terminal device performs cell selection or cell reselection based on the second parameter when the terminal device does not support SUL carrier transmission.

Abstract: This application provides a reflective QoS flow characteristic-based communications method and apparatus. In the method, an access-network network element sends first information to a core-network network element, where the first information is used to indicate whether a data packet has a reflective QoS flow characteristic; and the access-network network element determines, based on the first information, whether there is a need to send a QoS flow identifier to a terminal. In this way, signaling overheads are reduced.

Abstract: Example measurement methods and apparatus are described. One example method includes obtaining a timer by a terminal device. The terminal device obtains two or more measurement configurations, where each of two or more measurement configurations includes a validity area and a measurement frequency corresponding to the validity area, and the validity area includes one or more cells. The terminal device measures, based on the measurement configuration, a measurement frequency corresponding to a validity area that matches a cell on which the terminal device camps, where the terminal device is in an idle state or in an inactive state, and the timer is not stopped and has not expired.

Abstract: Embodiments of this application provide a communications method, apparatus, and system. The method includes: A terminal device receives first information sent by a network device, where the first information includes access control information of services with N service attributes, and N is an integer greater than or equal to 1; and the terminal device determines, based on a first service that currently needs to be initiated and the first information, whether the terminal device can initiate the first service, where the N service attributes include at least a non-public network service, and the first service is any one of the services with the N service attributes. Therefore, access control on the terminal device is implemented when there is a non-public network service.

Abstract: A method, a base station, and a system for sending radio resource control (RRC) signaling are provided. The method includes a pico base station and a macro base station participate in configuration and generation of an RRC reconfiguration message; the pico base station establishes only one RRC entity that is used to generate a configuration parameter or an RRC entity; the RRC reconfiguration message cooperatively generated by the pico base station and the macro base station is uniformly sent by the macro base station to a user equipment (UE). According to the application, the UE can support an RRC reconfiguration message sent by the pico base station, only by establishing a signaling radio bearer (SRB) corresponding to the macro base station. Accordingly, design complexity and costs are lowered.

Abstract: This application provides a transmission method and a data transmission apparatus, so as to avoid out-of-order of data packets.