Cell switching method and communication device

Abstract

The invention relates to the field of communication, in particular to a cell switching method and a communication device. In a carrier aggregation scene, a terminal can change an auxiliary cell used for communication, under normal conditions, the change of the auxiliary cell needs to be realized through auxiliary cell activation after a main cell is switched, a relatively long period of time needs to be taken from the start of the main cell switching to the completion of the auxiliary cell activation, and in the period of time, the change of the auxiliary cell is realized. A terminal cannot communicate by using carrier aggregation, so that the user experience is negatively influenced. In the method provided by the invention, the information for triggering the switching of the main cell can also be used for triggering the switching of the auxiliary cell, so that the switching of the auxiliary cell and the switching of the main cell can be synchronously carried out, and compared with a method for activating the auxiliary cell after the switching of the main cell is finished, the method provided by the invention can reduce the time delay for changing the auxiliary cell.

Description

Technical Field

[0001] This application relates to the field of communications, and particularly to a method for switching cells and a communication device. Background Art

[0002] Carrier aggregation (CA) is a technology for increasing transmission bandwidth, which can integrate multiple frequency-domain resources and improve resource utilization. In CA, the serving cell of a terminal includes a primary cell (PCell) and a secondary cell (SCell). Among them, the component carrier (CC) corresponding to the primary cell is called the primary component carrier (PCC), and the CC corresponding to the secondary cell is called the secondary component carrier (SCC). CA can aggregate one PCC and at least one SCC for use by the terminal.

[0003] CA can support the aggregation of 16 CCs. The terminal can only use some of them. In this case, if the traffic volume of the CC being used is large or the channel state is poor, the terminal can switch the CC being used, that is, switch cells. Cell switching requires operations such as time synchronization and channel measurement, and it takes a certain amount of time to complete cell switching. How to reduce the delay of cell switching is a problem that needs to be solved currently. Summary of the Invention

[0004] Embodiments of this application provide a method for switching cells, a communication device, a computer-readable storage medium, and a computer program product, which can reduce the delay of cell switching.

[0005] In a first aspect, embodiments of this application provide a method for switching cells. The execution subject of this method can be a terminal or a chip applied to a terminal. Hereinafter, the description will be made taking the execution subject as a terminal as an example. This method is applied to a terminal, and the serving cell of this terminal includes a first primary cell and a first secondary cell. This method includes: receiving first information, where the first information instructs the terminal to switch the primary cell from the first primary cell to a second primary cell, and the first information includes an identifier of a second secondary cell; and switching the primary cell from the first primary cell to the second primary cell according to the first information, and switching the secondary cell from the first secondary cell to the second secondary cell.

[0006] In this method, in addition to triggering the primary cell switching, the first information is also used to trigger the secondary cell switching, so that the secondary cell switching can be synchronized with the primary cell switching. Compared with the method of activating the secondary cell after the primary cell switching is completed, this method can reduce the delay of the secondary cell switching.

[0007] Optionally, before switching from the first secondary cell to the second secondary cell according to the first information, the method further includes: receiving a downlink synchronization signal of the second secondary cell; and obtaining time-frequency synchronization of the second secondary cell according to the downlink synchronization signal.

[0008] Optionally, obtaining time-frequency synchronization of the second secondary cell according to the downlink synchronization signal includes: obtaining time-frequency synchronization of the second secondary cell according to the downlink synchronization signal before receiving the first information.

[0009] Downlink synchronization can be performed before receiving the first information. For example, the terminal can receive synchronization signals of candidate secondary cells to complete downlink synchronization, and then does not need to perform downlink synchronization after receiving the first information, thereby reducing the delay of secondary cell handover.

[0010] Optionally, before switching from the first secondary cell to the second secondary cell, the method further includes: receiving a reference signal of the second secondary cell; and sending channel state information determined based on the reference signal.

[0011] Optionally, sending channel state information includes: sending channel state information before receiving the first information.

[0012] Channel state measurement can be performed before receiving the first information. For example, the terminal can receive reference signals of candidate secondary cells to complete channel state measurement, and then does not need to perform channel state measurement after receiving the first information, thereby reducing the delay of secondary cell handover.

[0013] Optionally, before receiving the first information, the method further includes: sending second information indicating that the terminal supports simultaneous primary cell handover and secondary cell handover.

[0014] Simultaneous primary cell handover and secondary cell handover requires the support of the terminal's capabilities. Some terminals may not have this capability. Therefore, after the terminal reports in advance that it has the capability to perform simultaneous primary cell handover and secondary cell handover, and then performs secondary cell handover based on the first information, it can avoid the failure of secondary cell handover caused by terminals that do not have this capability performing simultaneous primary cell handover and secondary cell handover.

[0015] Optionally, the first information further includes the cell-radio network temporary identifier (C-RNTI) of the terminal.

[0016] The terminal can obtain and store the C-RNTI of all candidate secondary cells in advance and use the C-RNTI of the target secondary cell after the secondary cell handover is completed. However, this method will increase the signaling overhead. In this method, the first information carries the C-RNTI of the target secondary cell, and there is no need to obtain and store the C-RNTI of all candidate secondary cells in advance, which can reduce the signaling overhead during the secondary cell handover process.

[0017] Optionally, the first information further includes an identifier of a second primary cell, and the identifier of the second primary cell is the same as the identifier of the first primary cell.

[0018] Since the identifier of the second primary cell is the same as the identifier of the first primary cell, the terminal can be understood as not needing to perform a primary cell handover and only performing a secondary cell handover. This implementation multiplexes the existing primary cell handover process to implement the function of separately switching secondary cells, and has better forward compatibility.

[0019] In a second aspect, an embodiment of the present application provides a method for switching cells. The execution subject of this method can be a base station or a chip applied to the base station. Hereinafter, the case where the execution subject is a base station will be described as an example. The method includes: sending first information, where the first information instructs the terminal to switch the primary cell from the first primary cell to the second primary cell, the first information includes an identifier of a second secondary cell, and the first information further instructs the terminal to switch the secondary cell from the first secondary cell to the second secondary cell. The first primary cell and the first secondary cell are serving cells of the terminal; switching the primary cell from the first primary cell to the second primary cell and switching the secondary cell from the first secondary cell to the second secondary cell.

[0020] The method in the second aspect corresponds to the method in the first aspect. The beneficial effects of the embodiments in the second aspect can refer to the beneficial effects of the corresponding embodiments in the first aspect and will not be elaborated here.

[0021] Optionally, the method further includes: sending a downlink synchronization signal of the second secondary cell.

[0022] Optionally, sending the downlink synchronization signal of the second secondary cell includes: sending the downlink synchronization signal of the second secondary cell before sending the first information.

[0023] Optionally, the method further includes: sending a reference signal of the second secondary cell; receiving channel state information, where the channel state information is determined based on the reference signal.

[0024] Optionally, sending the reference signal of the second secondary cell includes: sending the reference signal of the second secondary cell before sending the first information.

[0025] Optionally, before sending the first information, the method further includes: receiving second information, where the second information instructs the terminal to support simultaneous primary cell handover and secondary cell handover.

[0026] Optionally, the first information further includes the C-RNTI of the terminal.

[0027] Optionally, the first information further includes the identifier of the second primary cell, and the identifier of the second primary cell is the same as that of the first primary cell.

[0028] In a third aspect, an embodiment of the present application provides another method for switching cells. The execution subject of this method can be a terminal or a chip applied to the terminal. Hereinafter, the case where the execution subject is a terminal will be described as an example. The method includes: receiving third information, where the third information indicates that the terminal switches the secondary cell from the first secondary cell to the second secondary cell; and switching the secondary cell from the first secondary cell to the second secondary cell according to the third information.

[0029] In this method, the switching process of the secondary cell is decoupled from the switching process of the primary cell. The terminal switches the secondary cell according to the indication of the third information without caring whether the primary cell is switched. Compared with the method of activating the secondary cell after waiting for the primary cell switching to complete, this method can reduce the delay of secondary cell switching.

[0030] Optionally, before switching the secondary cell from the first secondary cell to the second secondary cell according to the third information, the method further includes: receiving the downlink synchronization signal of the second secondary cell; and obtaining the time-frequency synchronization of the second secondary cell through cell search according to the downlink synchronization signal.

[0031] Optionally, receiving the downlink synchronization signal of the second secondary cell includes: receiving the downlink synchronization signal of the second secondary cell before receiving the third information.

[0032] The downlink synchronization can be performed before receiving the third information. For example, the terminal can receive the synchronization signal of the candidate secondary cell to complete the downlink synchronization, and then no longer perform the downlink synchronization after receiving the third information, thereby reducing the delay of secondary cell switching.

[0033] Optionally, before switching the secondary cell from the first secondary cell to the second secondary cell according to the third information, the method further includes: receiving the reference signal of the second secondary cell; and sending channel state measurement information, where the channel state measurement information is determined based on the reference signal.

[0034] Optionally, receiving the reference signal of the second secondary cell includes: receiving the reference signal of the second secondary cell before receiving the third information.

[0035] The channel state measurement can be performed before receiving the third information. For example, the terminal can receive the reference signal of the candidate secondary cell to complete the channel state measurement, and then no longer perform the channel state measurement after receiving the third information, thereby reducing the delay of secondary cell switching.

[0036] Optionally, the third information includes the C-RNTI of the terminal.

[0037] The terminal can obtain and store the C-RNTIs of all candidate secondary cells in advance and use the C-RNTI of the target secondary cell after the secondary cell handover is completed. However, this method will increase the signaling overhead. In this method, the third information carries the C-RNTI of the target secondary cell, and there is no need to obtain and store the C-RNTIs of all candidate secondary cells in advance, which can reduce the signaling overhead during the secondary cell handover process.

[0038] In a fourth aspect, an embodiment of the present application provides another method for switching cells. The execution subject of this method can be a base station or a chip applied to the base station. Hereinafter, the case where the execution subject is a base station will be described as an example. The method includes: sending third information, where the third information instructs the terminal to switch the secondary cell from the first secondary cell to the second secondary cell; switching the secondary cell from the first secondary cell to the second secondary cell.

[0039] The method in the fourth aspect corresponds to the method in the third aspect. The beneficial effects of the embodiments in the fourth aspect can refer to the beneficial effects of the corresponding embodiments in the third aspect and will not be elaborated here.

[0040] Optionally, the method further includes: sending the downlink synchronization signal of the second secondary cell.

[0041] Optionally, sending the downlink synchronization signal of the second secondary cell includes: sending the downlink synchronization signal of the second secondary cell before sending the third information.

[0042] Optionally, the method further includes: sending the reference signal of the second secondary cell; receiving channel state measurement information, where the channel state measurement information is determined based on the reference signal.

[0043] Optionally, sending the reference signal of the second secondary cell includes: sending the reference signal of the second secondary cell before sending the third information.

[0044] Optionally, the third information includes the C-RNTI of the terminal.

[0045] In a fifth aspect, an embodiment of the present application provides a communication device. The communication device may include a processing unit and a transceiver unit for performing: any method in the first aspect and its optional implementation manners above, or any method in the third aspect and its optional implementation manners above. Wherein, the transceiver unit is a sending unit when performing the sending step, and the transceiver unit is a receiving unit when performing the receiving step.

[0046] Sixth aspect, an embodiment of the present application provides a communication device. The communication device may include a processing unit and a transceiver unit, and is configured to execute: any method in the second aspect and its optional embodiments described above, or any method in the fourth aspect and its optional embodiments described above. Wherein, when the transceiver unit executes the sending step, it is a sending unit, and when the transceiver unit executes the receiving step, it is a receiving unit.

[0047] Seventh aspect, an embodiment of the present application provides a communication device, which may be a terminal or a chip applied to a terminal. The communication device may include a processor, and is configured to execute: any method in the first aspect and its optional embodiments described above, or any method in the third aspect and its optional embodiments described above.

[0048] Optionally, the communication device may further include a transceiver. When the communication device is a terminal, the transceiver may be a transceiver circuit, an antenna, etc.; when the communication device is a chip applied to a terminal, the transceiver may be an input / output interface, a pin, a circuit, etc.

[0049] Optionally, the communication device may further include a memory, which is configured to store computer programs or instructions. The processor executes the computer programs or instructions stored in the memory, so that the communication device executes any method in the first aspect and its optional embodiments described above, or so that the communication device executes any method in the third aspect and its optional embodiments described above. When the communication device is a terminal, the memory may be a read-only memory, a random access memory, etc.; when the communication device is a chip applied to a terminal, the memory may be a register, a cache, etc.

[0050] Eighth aspect, an embodiment of the present application provides a communication device, which may be a base station or a chip applied to a base station. The communication device may include a processor, and is configured to execute: any method in the second aspect and its optional embodiments described above, or any method in the fourth aspect and its optional embodiments described above.

[0051] Optionally, the communication device may further include a transceiver. When the communication device is a base station, the transceiver may be a transceiver circuit, an antenna, etc.; when the communication device is a chip applied to a base station, the transceiver may be an input / output interface, a pin, a circuit, etc.

[0052] Optionally, the communication device may further include a memory for storing computer programs or instructions. The processor executes the computer programs or instructions stored in the memory, so that the communication device executes any of the methods in the second aspect and its optional embodiments above, or so that the communication device executes any of the methods in the fourth aspect and its optional embodiments above. When the communication device is a base station, the memory may be a read-only memory, a random access memory, etc.; when the communication device is a chip applied to a base station, the memory may be a register, a cache, etc.

[0053] In a ninth aspect, an embodiment of the present application provides a communication system, which includes: the communication device described in the fifth aspect and the communication device described in the sixth aspect, or the communication device described in the seventh aspect and the communication device described in the eighth aspect.

[0054] In a tenth aspect, an embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed on a communication device, the communication device is caused to execute: any of the methods in the first aspect and its optional embodiments, or any of the methods in the second aspect and its optional embodiments, or any of the methods in the third aspect and its optional embodiments, or any of the methods in the fourth aspect and its optional embodiments.

[0055] In an eleventh aspect, an embodiment of the present application provides a computer program product, which includes: computer program code or computer program instructions. When the computer program code or computer program instructions are run on a communication device, the communication device is caused to execute: any of the methods in the first aspect and its optional embodiments, or any of the methods in the second aspect and its optional embodiments, or any of the methods in the third aspect and its optional embodiments, or any of the methods in the fourth aspect and its optional embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a schematic diagram of the architecture of the communication system to which the embodiments of the present application are applied;

[0057] Figure 2 is a schematic diagram of the resource configuration of a tracking reference signal provided by an embodiment of the present application;

[0058] Figure 3 is a schematic diagram of a carrier aggregation scenario provided by an embodiment of the present application;

[0059] Figure 4 is a schematic diagram of a cell handover scenario provided by an embodiment of the present application;

[0060] Figure 5 It is a schematic flowchart of primary cell handover and secondary cell activation provided by an embodiment of the present application;

[0061] Figure 6 It is a schematic flowchart of a method for switching cells provided by an embodiment of the present application;

[0062] Figure 7 It is a schematic flowchart of primary cell handover and secondary cell handover provided by an embodiment of the present application;

[0063] Figure 8 It is another schematic flowchart of primary cell handover and secondary cell handover provided by an embodiment of the present application;

[0064] Figure 9 It is still another schematic flowchart of primary cell handover and secondary cell handover provided by an embodiment of the present application;

[0065] Figure 10 It is a schematic diagram of a secondary cell handover scenario provided by an embodiment of the present application;

[0066] Figure 11 It is a schematic flowchart of another method for switching cells provided by an embodiment of the present application;

[0067] Figure 12 It is a schematic flowchart of secondary cell handover provided by an embodiment of the present application;

[0068] Figure 13 It is another schematic flowchart of secondary cell handover provided by an embodiment of the present application;

[0069] Figure 14 It is still another schematic flowchart of secondary cell handover provided by an embodiment of the present application;

[0070] Figure 15 It is a schematic diagram of the structure of a communication device provided by an embodiment of the present application;

[0071] Figure 16 It is another schematic diagram of the structure of a communication device provided by an embodiment of the present application. Detailed implementation manners

[0072] Figure 1 It is a schematic diagram of the architecture of a communication system 1000 to which an embodiment of the present application is applied. As Figure 1 shown, the communication system includes a radio access network (RAN) 100, where the RAN 100 includes at least one RAN node (such as Figure 1 110a and 110b inFigure 1 120a - 120j in it, collectively referred to as 120). RAN 100 may also include other RAN nodes, for example, wireless relay devices and / or wireless backhaul devices ( Figure 1 not shown in the figure). The terminal 120 is connected to the RAN node 110 wirelessly. Terminals can be connected to each other and RAN nodes can be connected to each other either by wire or wirelessly. The communication system 1000 may also include a core network 200. The RAN node 110 is connected to the core network 200 either wirelessly or by wire. The core network devices in the core network 200 and the RAN nodes 110 in the RAN 100 can be independent different physical devices, or the same physical device integrating the logical functions of the core network devices and the logical functions of the RAN nodes. The communication system 1000 may also include the Internet 300.

[0073] RAN 100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, or a future wireless access system defined in the 3rd generation partnership project (3GPP), or a WiFi system. RAN 100 may also include two or more different wireless access systems as described above. RAN 100 can also be an open RAN (O-RAN).

[0074] The RAN node, also known as a network device, a radio access network device, a RAN entity, or an access node, is used to help terminals access the communication system wirelessly.

[0075] In one application scenario, the RAN node can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) in the 5th generation (5G) mobile communication system, a next generation NodeB in the 6th generation (6G) mobile communication system, a base station in a future mobile communication system, an access point (AP) in a WiFi system, an AP in a long range radio (LoRa) system, or an AP in a vehicle-to-everything (V2X) system. The RAN node can be a macro base station (such as Figure 1 110a in the figure), or a micro base station or an indoor station (such asFigure 1 In 110b), it can also be a relay node or a donor node.

[0076] In another application scenario, the wireless access of a terminal can be assisted by the cooperation of multiple RAN nodes, and different RAN nodes respectively implement some functions of the base station. For example, the RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). Here, the CU completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the function of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control layer and the medium access control (MAC) layer of the base station, and can also complete some or all of the functions of the physical layer. For the specific descriptions of the above various protocol layers, reference can be made to the relevant technical specifications of 3GPP. The RU can be used to implement the functions of transmitting and receiving radio frequency signals. The CU and the DU can be two independent RAN nodes, or can be integrated in the same RAN node, for example, integrated in the baseband unit (BBU). The RU can be included in the radio frequency device, for example, included in the remote radio unit (RRU), the active antenna unit (AAU), or the remote radio head (RRH). The CU can be further divided into two types of RAN nodes: CU-control plane and CU-user plane.

[0077] In different systems, the RAN node may have different names. For example, in the O-RAN system, the CU can be called an open CU (O-CU), the DU can be called an open DU (O-DU), and the RU can be called an open RU (O-RU). The RAN node in the embodiments of the present application can be implemented in the form of a software module, a hardware module, or a combination of a software module and a hardware module. For example, the RAN node can be a server loaded with the corresponding software module. The embodiments of the present application do not limit the specific technologies and specific device forms adopted by the RAN node. For the convenience of description, the base station is used as an example of the RAN node in the following description.

[0078] A terminal is a device with wireless transceiver capabilities that can send signals to a base station or receive signals from a base station. A terminal can also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely applied in various scenarios, such as device-to-device (D2D), vehicle to everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, etc. A terminal can be a mobile phone (such as Figure 1 120a, 120e, 120f, and 120j in Figure 1 ), a tablet computer (such as Figure 1 120g in Figure 1 ), a printer with wireless transceiver capabilities (such as Figure 1 120h in Figure 1 ), a wearable device, a vehicle (such as Figure 1 120b in

[0079] ), a charging pile (such as

[0080] 120c in Figure 1 ), an airplane (such as Figure 1 120i in Figure 1 ), a ship, a robot, a robotic arm, a smart home device (such as Figure 1 120d in Figure 1 ), etc. Embodiments of the present application do not limit the specific technologies and specific device forms adopted by the terminal.

[0079] As an example and not a limitation, in embodiments of the present application, a wearable device can also be referred to as a wearable intelligent device, which is a general term for devices developed by applying wearable technologies to the intelligent design of daily wear, such as glasses, gloves, watches, clothing, and shoes. A wearable device is a portable device that is directly worn on the body or integrated into the user's clothes or accessories. A wearable device is not just a hardware device, but also realizes powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable intelligent devices include electronic devices with complete functions, large sizes, and that can realize complete or partial functions without relying on a smart phone, such as smart watches or smart glasses, or electronic devices that only focus on a certain type of application function and need to cooperate with other devices such as smart phones, such as various smart bracelets and smart jewelry for measuring physical signs.

[0080] Among the various terminals introduced above, if they are located on a vehicle (for example, placed inside or installed inside a vehicle), they can all be considered on-vehicle terminals, which can also be referred to as on-vehicle modules, on-vehicle components, on-vehicle chips, or on-board units (OBUs).

[0081] The base station and the terminal can be in fixed positions or movable. The base station and the terminal can be deployed on land, including indoors or outdoors, handheld or on-vehicle; they can also be deployed on water; they can also be deployed on airplanes, balloons, and artificial satellites. The embodiments of the present application do not limit the application scenarios of the base station and the terminal.

[0082] The roles of the base station and the terminal can be relative. For example, Figure 1 the 120i in [reference] can be configured as a mobile base station. For those 120j that access the radio access network 100 through the 120i, the 120i is the base station; but for the 110a, the 120i is the terminal, that is, the communication between the 110a and the 120i is through the radio air interface protocol. Of course, the communication between the 110a and the 120i can also be through the interface protocol between base stations. At this time, relative to the 110a, the 120i is also the base station. Therefore, both the base station and the terminal can be uniformly referred to as communication devices. Figure 1 the 110a and 110b in [reference] can be referred to as communication devices with base station functions. Figure 1 the 120a - 120j in [reference] can be referred to as communication devices with terminal functions.

[0083] The communication between the base station and the terminal, between the base station and the base station, and between the terminal and the terminal can be through authorized spectrum, can be through unlicensed spectrum, or can be through both authorized spectrum and unlicensed spectrum at the same time; it can communicate through spectrum below 6 gigahertz (GHz), can communicate through spectrum above 6 GHz, or can also use both spectrum below 6 GHz and spectrum above 6 GHz at the same time. The embodiments of the present application do not limit the spectrum resources used for wireless communication.

[0084] In the embodiments of the present application, the functions of the base station can also be executed by modules (such as chips) in the base station, or can be executed by a control subsystem including base station functions. The control subsystem including base station functions here can be a control center in the above application scenarios such as smart grid, industrial control, intelligent transportation, and smart city. The functions of the terminal can also be executed by modules (such as chips or modems) in the terminal, or can be executed by a device including terminal functions.

[0085] In an embodiment of the present application, the base station sends downlink information to the terminal. The downlink information is carried on a downlink channel and can also be referred to as a downlink signal. The terminal sends uplink information to the base station. The uplink information is carried on an uplink channel and can also be referred to as an uplink signal. In order to communicate with the base station, the terminal needs to establish a wireless connection on a cell controlled by the base station. The cell with which the terminal has established a wireless connection is called the serving cell of the terminal.

[0086] To facilitate the understanding of the embodiments of the present application, the technologies involved in the embodiments of the present application are briefly introduced below.

[0087] 1. Time-frequency resources.

[0088] In an embodiment of the present application, data or information can be carried by time-frequency resources. Among them, the time-frequency resources can include resources in the time domain and resources in the frequency domain. Among them, in the time domain, the time-frequency resources can include one or more time domain units (which can also be referred to as time units). In the frequency domain, the time-frequency resources can include one or more frequency domain units.

[0089] A time domain unit can be a symbol, a mini-slot, a slot, or a subframe. Among them, the duration of a subframe in the time domain can be 1 millisecond (ms). A slot can include 7 or 14 symbols. A mini-slot can include at least one symbol, and the symbol can be an orthogonal frequency division multiplexing (OFDM) symbol or a discrete Fourier transformation spread OFDM (DFT-s-OFDM) symbol.

[0090] A frequency domain unit can be a subcarrier, a resource block (RB), a resource block group (RBG), a subband, a precoding resource block group (PRG), a bandwidth part (BWP), a resource element (RE), a carrier, or a serving cell.

[0091] The above-listed time domain units and frequency domain units are only for facilitating the understanding of the embodiments of the present application and do not limit the protection scope of the present application. The present application does not limit the specific forms of the time domain units and frequency domain units.

[0092] 2. Measurement

[0093] Mobility management is an important part of wireless mobile communication, and measurement is the basis of mobility management. Mobility management refers to the general term for the relevant content involved in ensuring that the communication link between the base station and the terminal is not interrupted due to the movement of the terminal.

[0094] As an optional implementation manner, measurements can be classified into layer 1 (L1) measurements, layer 2 (L2) measurements, and layer 3 (L3) measurements according to the involved layers. Among them, L1 measurements can also be called physical layer measurements, L2 measurements can also be called MAC layer measurements, and L3 measurements can also be called radio resource control (RRC) layer measurements. The terminal can perform specified types of measurements according to the measurement configuration.

[0095] The measurement configuration can include measurement targets. The measurement targets can include, for example, frequency points and / or cell identifiers. Among them, the cell identifier can include a cell global identifier (CGI) or a physical cell identifier (PCI).

[0096] The measurement configuration can include a synchronization signal and physical broadcast channel block (SSB)-based measurement timing configuration (SMTC). The SMTC can include one or more of the period, length, and offset of the SSB. Thus, the terminal can receive the SSB according to the SMTC and perform operations such as measurements based on the SSB.

[0097] The measurement configuration can include the measurement valid time. The measurement valid time can indicate the time length for which the terminal needs to perform the measurement. After receiving the measurement configuration, the terminal can start a timer, and the running duration of the timer can be the measurement valid time. When the timer stops or expires, the terminal can stop performing the measurement based on the parameters in the measurement configuration.

[0098] The measurement configuration may, for example, further include a measurement valid area. The measurement valid area may be shown, for example, in the form of a cell identifier and / or an area identifier, etc. Among them, the cell identifier may be a CGI. The area identifier may be, for example, a tracking area code (TAC) and / or a radio access network area code (RANAC). When the terminal moves outside the measurement valid area, the terminal may stop the measurement based on the parameters in the measurement configuration.

[0099] For example, after the terminal obtains the measurement valid time and the measurement valid area, when the timer is running, if the terminal moves outside the measurement valid area, the terminal may stop the timer and stop the measurement based on the parameters in the measurement configuration.

[0100] It should be understood that the parameters included in the measurement configuration listed above are examples rather than limitations. The measurement configuration may include one or more parameters such as the measurement valid time, the measurement target, the SMTC corresponding to the measurement target, and the measurement valid area, and may also include more other parameters.

[0101] It should be noted that the specific parameters of the above measurement configuration may be configured by one message or by different messages. The embodiments of the present application do not limit this. For example, the measurement target may be indicated in the measurement configuration carried in the system message, and the measurement valid time may be indicated in the measurement configuration carried in the RRC message (such as, the RRC release message or the RRC connection release message).

[0102] It should also be noted that when the terminal receives the measurement configuration in the RRC message and the measurement configuration in the system message, the measurement configuration in the RRC message may be preferentially used. Relative to the system message, this RRC message may be referred to as a dedicated signaling for sending the measurement configuration. In other words, the terminal may preferentially use the parameters for measurement obtained from the RRC message. When a parameter (such as the measurement target) configured in the RRC message is missing, the terminal may obtain the missing parameter from the system message.

[0103] Based on the measurement, the terminal can obtain the measurement result of the measurement target. The measurement result may include a cell identifier and / or a frequency point. Optionally, the measurement result may include the signal quality of the cell. Among them, the signal quality may include at least one of received signal code power (RSCP), reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), signal noise ratio (SNR), signal to interference plus noise ratio (SINR), reference signal strength indication (RSSI), and other signal quality information. The signal quality may be at the cell level, beam level, SSB level, numerology level, slicing level, or BWP level.

[0104] The terminal can report the measurement result after accessing the cell. For example, the terminal can report the measurement result after receiving any one of the RRC setup message, RRC resume message, RRC connection setup message, or RRC connection resume message.

[0105] 3. Tracking Reference Signal (TRS).

[0106] 3GPP has defined the channel state information reference signal (CSI-RS) for tracking, and this reference signal is also called TRS.

[0107] The TRS of the NR system is a specialized CSI-RS, which is configured through a non-zero power channel state information reference signal resource set (CSI-RS Resource Set), and the CSI-RS Resource Set can also be called the TRS resource set. Each CSI-RS Resource Set contains 2 or 4 CSI-RS resources. A CSI-RS resource refers to the RE used to transmit CSI-RS in a symbol with a certain frequency domain density and bandwidth. The symbol positions of each CSI-RS resource are different, but their transmission bandwidths, densities, and frequency domain positions are the same. As Figure 2 shown, for frequency range (FR) 1, each CSI-RS Resource Set contains 4 CSI-RS resources, and these 4 CSI-RS resources are located in 2 time slots (such as Figure 2 the time slot 1 and time slot 2 corresponding to the FR1 frequency band shown), and the 2 CSI-RS resources in one time slot are separated by 3 symbols; for FR2, each CSI-RS Resource Set contains 2 CSI-RS resources, and these 2 CSI-RS resources are separated by 3 symbols in one time slot (such as Figure 2 the time slot 1 corresponding to the FR2 frequency band shown). It can be seen that the symbol positions of each CSI-RS resource in the time slot are different, but their transmission bandwidths, densities, and frequency domain positions are the same.

[0108] There are two TRS transmission methods. One is periodic transmission. As Figure 2 shown, each CSI-RS Resource set (occupying 2 or 4 symbols) represents a TRS burst in a transmission cycle, and usually there is one TRS burst in a transmission cycle. The other TRS transmission method is aperiodic transmission. The aperiodic TRS (aperiodic tracking reference signal, A-TRS) can be triggered by downlink control information (DCI).

[0109] TRS is mainly used for the terminal to perform accurate time-frequency synchronization. The base station configures multiple TRS resource sets for the terminal. Each TRS resource set and an SSB have a C-type quasi co-location (QCL) relationship, that is, the terminal can first perform rough time-frequency synchronization based on the SSB, and then receive the TRS using the channel parameters provided by the rough time-frequency synchronization to obtain the TRS channel information. The physical downlink control channel (PDCCH) received by the terminal in the connected state has a QCL-TypeA relationship with the TRS, and the physical downlink shared channel (PDSCH) received by the terminal in the connected state also has a QCL-TypeA relationship with the TRS. Therefore, the TRS can provide accurate time-frequency synchronization information for the PDCCH and PDSCH.

[0110] In addition to accurate time-frequency synchronization, the TRS can also be used for functions such as automatic gain control (AGC) and signal to interference ratio (SIR) estimation of the terminal.

[0111] 4. Carrier Aggregation.

[0112] CA is a technology in which a single terminal uses multiple CCs to jointly perform data transmission, which can achieve large-bandwidth transmission and effectively improve the uplink or downlink transmission rate. The terminal can decide how many CCs can be used for transmission at most according to its own capabilities. As an example, in a 3-carrier aggregation scenario, the terminal can use 3 CCs simultaneously.

[0113] Figure 3 Figure 13 is a schematic diagram of a 3-carrier aggregation scenario. In this scenario, the base station provides 3 CCs. The cells corresponding to these 3 CCs are Cell 1, Cell 2, and Cell 3 respectively. The terminal establishes an RRC connection with Cell 1, then Cell 1 is the PCell, and the CC corresponding to the PCell is the PCC. The terminal establishes a communication connection with Cell 2 and Cell 3 during RRC reconfiguration, and this communication connection is not an RRC connection, so Cell 2 and Cell 3 are SCell, and the CCs corresponding to the SCell are SCC. CA allows the PDCCH and PDSCH to be carried on different CCs, that is, cross-carrier scheduling is allowed.

[0114] The number of CCs supported by a base station is usually greater than that supported by a terminal. For example, a base station can support carrier aggregation of 16 downlink CCs, while a terminal usually supports carrier aggregation of 2 to 3 downlink CCs. However, the terminal can select 2 to 3 downlink CCs from these 16 downlink CCs for carrier aggregation. If the currently used CC experiences busy traffic or poor channel conditions, etc., the terminal can switch CCs, that is, switch cells. In this way, it can not only match the terminal capabilities but also achieve load balancing of the base station, thereby improving the user experience.

[0115] In various embodiments of the present application, carrier, CC, and cell are all concepts used to describe frequency domain resources. Under the condition of no logical conflict, the three can be equivalently replaced.

[0116] 5. Cell handover.

[0117] A cell can be regarded as a wireless signal coverage area identified by PCI or CGI. The coverage area of each base station can be divided into one or more cells. In the embodiments of the present application, different cells can correspond to different base stations. For example, the base station corresponding to cell 1 and the base station corresponding to cell 2 can be different base stations, that is to say, cell 1 and cell 2 can be managed by different base stations. The base station corresponding to cell 1 and the base station corresponding to cell 2 can also be the same base station, that is to say, cell 1 and cell 2 can be managed by the same base station. This situation can be called co-site of cell 1 and cell 2. Optionally, when cell 1 and cell 2 are co-site, cell 1 and cell 2 have the same baseband processing unit and intermediate frequency processing unit, but have different radio frequency processing units.

[0118] The cells providing services for a terminal can be divided into PCell and SCell. Therefore, both PCell and SCell can be called the serving cells of the terminal. In the CA scenario, a base station can configure one PCell and one or more SCell for a terminal. Among them, the PCell is the cell where the terminal maintains an RRC connection, and the remaining serving cells of the terminal can be called SCell. The SCell can be flexibly activated / deactivated through DCI or MAC control element (CE). After the RRC connection is established, the base station can configure SCell for the terminal to provide additional wireless resources.

[0119] The above description of the cell is an example rather than a limitation. With the development of technology, concepts identical or similar to the function of the cell may appear, and these concepts are also applicable to the embodiments of the present application.

[0120] Due to the mobility of the terminal or the change of the channel state, the cell to which the terminal is connected will change. That is, the terminal can switch from one cell to another. Among them, the cell before the switch can be called the source cell or the anchor cell, and the cell after the switch can be called the target cell. As an optional example, cell handover can be interpreted as the terminal transmitting on the target cell indicated by the handover signaling and stopping transmitting on the source cell, or cell handover can be interpreted as the change of the transmitting cell.

[0121] Figure 4 It is a schematic diagram of a cell handover scenario. Figure 4 In the figure, the terminal is currently communicating using 2 carriers (CC1 and CC2). Among them, the cell corresponding to CC1 is the PCell, and the cell corresponding to CC2 is the SCell. The terminal also supports communicating using CC3 and CC4, but CC3 and CC4 are not activated. The cells corresponding to CC3 and CC4 are non-serving cells. As the terminal moves, the channel states of CC1 and CC2 deteriorate. The terminal can communicate using CC3 and CC4 and no longer use CC1 and CC2 for communication. For example, the terminal switches from the cell corresponding to CC1 to the cell corresponding to CC3, and switches from the cell corresponding to CC2 to the cell corresponding to CC4. The cells corresponding to CC1 and CC2 are the cells before the switch and can be called the source cells, and the cells corresponding to CC3 and CC4 are the cells after the switch and can be called the target cells. After the cell handover is completed, the cell corresponding to CC3 is the PCell, the cell corresponding to CC4 is the SCell, and the cells corresponding to CC1 and CC2 become non-serving cells. The process from CC1 to CC3 can be called PCell handover, and the process from CC2 to CC4 can be called SCell handover, or the process from CC2 to CC4 can be called SCell activation.

[0122] It should be understood that cell handover may be from a cell of one base station to a cell of another base station, or may be a handover between different cells of the same base station. In addition, cell handover can be triggered by the base station, can be triggered by the terminal, or can be triggered by a third-party device other than the base station and the terminal.

[0123] In Figure 4 In the shown scenario, the base station can use MAC CE to trigger the handover of the PCell. After the PCell handover is completed, the activation of the SCell can be completed through cell activation. The procedures of PCell handover and SCell activation are as shown in Figure 5 shown.

[0124] Figure 5Among them, the terminal can complete the downlink synchronization and uplink synchronization with the target PCell before receiving the MAC CE indicating the PCell handover. After receiving the MAC CE indicating the PCell handover, the terminal performs the PCell handover. The PCell handover process includes steps such as the processing of MAC CE, the reconfiguration of L2 / L3, baseband retuning, and radio frequency retuning. After the PCell handover is completed, the base station sends a signaling (such as MAC CE) indicating the activation of the SCell to the terminal, and the terminal performs the SCell activation according to the signaling for activating the SCell. The SCell activation process includes steps such as the parsing of MAC CE, the hybrid automatic repeat request (HARQ) process, the activation process based on SSB or TRS, and the reporting of channel state information (CSI).

[0125] Figure 5 In the handover process shown, it takes about 20 - 55 ms from the start of PCell handover to the completion of the activation of the target SCell. This is a relatively long time. During this period, the terminal cannot use carrier aggregation for communication, which has a negative impact on the user experience.

[0126] Next, the method for handover of cells provided in the embodiments of the present application will be introduced with reference to the accompanying drawings.

[0127] Figure 6 It is a schematic flowchart of a method for handover of cells provided in the embodiments of the present application. As Figure 6 shown, in method 600, the serving cell of the terminal includes a first primary cell and a first secondary cell. Method 600 includes:

[0128] S610, the terminal receives first information, and the first information indicates that the terminal will hand over the primary cell from the first primary cell to the second primary cell. The first information includes the identifier of the second secondary cell.

[0129] Correspondingly, the base station generates and sends the first information.

[0130] In various embodiments of the present application, "the first information instructs the terminal to switch the primary cell from the first primary cell to the second primary cell" may also be expressed as: the first information instructs the terminal to transmit RRC signaling on the second primary cell; or it may also be expressed as: the RRC connection of the terminal with the base station is switched from the first primary cell to the second primary cell. Correspondingly, for the terminal or the base station, "switching the primary cell from the first primary cell to the second primary cell" may be expressed as: transmitting RRC signaling on the second primary cell; or, "switching the primary cell from the first primary cell to the second primary cell" may be expressed as: transmitting RRC signaling on the second primary cell, and stopping transmitting RRC signaling on the first primary cell; or, "switching the primary cell from the first primary cell to the second primary cell" may be expressed as: transmitting RRC signaling on the second primary cell, where the first primary cell is the primary serving cell before receiving (or, sending) the first information, and the second primary cell is the primary serving cell after receiving (or, sending) the first information. "Switching the secondary cell from the first secondary cell to the second secondary cell" may be expressed as: performing data transmission on the second secondary cell; or, "switching the secondary cell from the first secondary cell to the second secondary cell" may be expressed as: performing data transmission on the second secondary cell, and stopping performing data transmission on the first secondary cell; or, "switching the secondary cell from the first secondary cell to the second secondary cell" may be expressed as: performing data transmission on the second secondary cell, where the first secondary cell is the serving cell before receiving (or, sending) the first information, the second secondary cell is the non-serving cell, and the first secondary cell is the non-serving cell and the second secondary cell is the serving cell after receiving (or, sending) the first information.

[0131] In various embodiments of the present application, "the first information instructs the terminal to switch the primary cell from the first primary cell to the second primary cell" may also be expressed as: the first information instructs the terminal to change the primary cell to the second primary cell. Correspondingly, for the terminal or the base station, "switching the primary cell from the first primary cell to the second primary cell" may be expressed as: changing the primary cell to the second primary cell; "switching the secondary cell from the first secondary cell to the second secondary cell" may be expressed as: changing the secondary cell to the second secondary cell. Among them, "changing" can be interpreted as "switching".

[0132] The first information is information generated and sent by the base station corresponding to the first primary cell (i.e., the source PCell). The first information may be an RRC message, a MAC CE, or a DCI, or may also be a field in an RRC message, a MAC CE, or a DCI.

[0133] The first information can be indicated in an explicit manner or in an implicit manner. When in the explicit manner, the first information may include a dedicated field, such as a first field. When the value of the first field is "1", the first field in combination with the identifier of the second primary cell instructs the terminal to handover from the first primary cell to the second primary cell, where the identifier of the second primary cell can be sent to the terminal separately or together with the first field; when the value of the first field is "0", it instructs the terminal not to perform a primary cell handover. When in the implicit manner, the first information can reuse some fields for indication. For example, the MAC CE may include the identifier of the second primary cell, and the identifier of the second primary cell indicates the target PCell. The first information can reuse the identifier of the second primary cell. When the terminal receives the identifier of the second primary cell, the terminal determines to perform a primary cell handover and determines that the target PCell is the second primary cell.

[0134] Embodiments of the present application do not limit the specific form of the first information and the sending manner of the first information.

[0135] The identifier of the second secondary cell may be a PCI, a CGI or a serving cell index, or other information for identifying the second secondary cell. Embodiments of the present application do not limit the specific form of the identifier of the second secondary cell.

[0136] The first information including the identifier of the second secondary cell further instructs the terminal to handover from the first secondary cell to the second secondary cell, where the first information can be indicated in an explicit manner or in an implicit manner. When in the explicit manner, the first information may include a dedicated field, such as a second field. When the value of the second field is "1", the second field in combination with the identifier of the second secondary cell instructs the terminal to handover from the first secondary cell to the second secondary cell, where the identifier of the second secondary cell can be sent to the terminal separately or together with the second field; when the value of the second field is "0", it instructs the terminal not to perform a secondary cell handover. When in the implicit manner, the first information can reuse some fields for indication. For example, the identifier of the second secondary cell indicates the target SCell. The first information can reuse the identifier of the second secondary cell. When the terminal receives the identifier of the second secondary cell, the terminal determines to perform a secondary cell handover and determines that the target SCell is the second secondary cell.

[0137] Before sending the first message, the base station may configure a set of candidate cells, which includes at least one candidate primary cell and / or at least one candidate secondary cell. Alternatively, the base station may configure two sets of candidate cells, where one set of candidate cells includes at least one candidate primary cell and the other set of candidate cells includes at least one candidate secondary cell. Taking the former case as an example, the base station may configure a set of candidate cells including 4 cells for the terminal through an RRC message. The 4 cells are Cell 1, Cell 2, Cell 3, and Cell 4 respectively. If the identifier of the second secondary cell carried in the first message is the identifier of Cell 4, the terminal may determine that the second secondary cell is Cell 4; optionally, if the first message also carries the identifier of the second primary cell, and the identifier of the second primary cell is the identifier of Cell 3, the terminal may determine that the second primary cell is Cell 3. By pre-configuring the set of candidate cells, the base station can pre-configure some parameters of the target cell to the terminal in advance, reducing the delay of cell handover.

[0138] After receiving the first message, the terminal may perform the following steps.

[0139] S620, switch the primary cell from the first primary cell to the second primary cell according to the first message, and switch the secondary cell from the first secondary cell to the second secondary cell.

[0140] Before the terminal switches to the second secondary cell, it needs to perform operations such as downlink synchronization and channel state measurement. The terminal may complete the downlink synchronization with the second primary cell before receiving the first message. Therefore, the terminal may determine the measurement configuration of the second secondary cell, such as SMTC, through the downlink synchronization information of the second primary cell, and then receive the downlink synchronization signal (such as, SSB) of the second secondary cell based on the measurement configuration of the second secondary cell, and perform operations such as downlink synchronization according to the downlink synchronization signal. Among them, performing downlink synchronization may be to perform cell search to obtain the time-frequency synchronization of the second secondary cell.

[0141] During the cell handover process, the C-RNTI allocated by the base station to the terminal needs to be updated. For example, during the handover from the first secondary cell to the second secondary cell, the C-RNTI of the terminal needs to be updated from the first C-RNTI (the C-RNTI allocated by the first secondary cell to the terminal) to the second C-RNTI (the C-RNTI allocated by the second secondary cell to the terminal). One implementation method is that each candidate cell allocates a C-RNTI to the terminal, and the first primary cell can send the C-RNTIs allocated by all candidate cells to the terminal to the terminal through an RRC message before sending the first information; another implementation method is that the first information carries the C-RNTI allocated by the target cell (such as the second primary cell and the second secondary cell) to the terminal. Since the number of C-RNTIs carried by the first information is less than the number of C-RNTIs carried by the RRC message, the latter implementation method reduces the signaling overhead caused by updating the C-RNTI compared to the former implementation method.

[0142] After the terminal obtains the measurement configuration of the second secondary cell and the C-RNTI allocated by the second secondary cell to the terminal, it can perform the operation of handing over to the second secondary cell. It can be seen that in method 600, the handover of the secondary cell can be synchronized with the handover of the primary cell. Compared with the method of activating the secondary cell after waiting for the handover of the primary cell to be completed, method 600 can reduce the latency of the handover of the secondary cell.

[0143] The handover of the secondary cell includes operations such as downlink synchronization and channel state measurement. Among them, downlink synchronization and channel state measurement can be performed before receiving the first information or after receiving the first information. Different situations are introduced in detail below. It should be noted that the various operations (such as synchronization, channel measurement, etc.) mentioned in the embodiments of the present application and the execution order of the various operations are examples rather than limitations. The handover of the primary cell and the handover of the secondary cell may also include other operations, and the embodiments of the present application do not limit the specific operations during the handover process of the primary cell and the secondary cell.

[0144] Situation 1: Downlink synchronization and channel state measurement are performed after receiving the first information.

[0145] Optionally, in method 600, the procedures for handover of the primary cell and the secondary cell are as Figure 7 shown. Figure 7Among them, the terminal can complete the downlink synchronization and uplink synchronization with the second primary cell (i.e., the target PCell) before receiving the MAC CE (an example of the first information) indicating the primary cell handover. After receiving the MAC CE indicating the primary cell handover, the terminal performs the primary cell handover. For example, the base station can pre-configure candidate primary cells, and the terminal performs downlink synchronization and uplink synchronization with each candidate primary cell; the identity of the second primary cell is carried in the MAC CE, and the second primary cell belongs to the pre-configured candidate primary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE, reconfiguring L2 / L3, baseband retuning, and radio frequency retuning, without having to perform downlink synchronization and uplink synchronization with the second primary cell again.

[0146] After the terminal receives the MAC CE indicating the primary cell handover, it can receive the SSB, periodic TRS (periodic TRS, P-TRS), or A-TRS of the second secondary cell (i.e., the target SCell), and perform operations such as AGC and downlink synchronization. During the downlink synchronization process, the terminal can first perform coarse synchronization and then fine synchronization.

[0147] After the downlink synchronization is completed, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement according to the reference signal, generate channel state information, and send the channel state information to the first primary cell. Among them, the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0148] The above channel state measurement can be semi-persistent measurement, that is, the base station pre-configures periodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover triggers the periodic CSI-RS resources to take effect. When the terminal receives the MAC CE, it starts to receive CSI-RS on the periodic CSI-RS resources, performs channel state measurement and reporting.

[0149] The above channel state measurement can also be aperiodic measurement, that is, the base station pre-configures aperiodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover carries an indication to trigger aperiodic CSI measurement. When the terminal receives the MAC CE, it starts to receive CSI-RS on the aperiodic CSI-RS resources, performs channel state measurement and reporting, so that the base station can obtain the channel state information earlier.

[0150] After the base station receives the channel state information, it considers that the secondary cell handover is completed.

[0151] Based on Figure 7For the process shown, the start time of the handover delay of the secondary cell can be defined as the time when the terminal receives the MAC CE indicating the handover of the primary cell, and the end time of the handover delay of the secondary cell can be defined as the time when the terminal transmits the channel state information. Among them, the handover delay of the secondary cell includes: the time for the terminal to parse the MAC CE, the time for the terminal to feedback the reception situation of the MAC CE based on HARQ, the time for the terminal to perform downlink synchronization based on the SSB or A-TRS, and the time for the terminal to perform channel state measurement and reporting, etc.

[0152] Case 2: Downlink synchronization is performed before receiving the first information, and channel state measurement is performed after receiving the first information.

[0153] Optionally, in method 600, the processes of primary cell handover and secondary cell handover are as Figure 8 shown. Figure 8 In this case, the terminal can complete downlink synchronization and uplink synchronization with the second primary cell (i.e., the target PCell) before receiving the MAC CE indicating the handover of the primary cell. After receiving the MAC CE indicating the handover of the primary cell, the terminal performs the primary cell handover. For example, the base station can pre-configure candidate primary cells, and the terminal performs downlink synchronization and uplink synchronization with each candidate primary cell; the second primary cell identifier is carried in the MAC CE, and the second primary cell belongs to the pre-configured candidate primary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE, reconfiguring L2 / L3, baseband retuning, and radio frequency retuning, without having to perform downlink synchronization and uplink synchronization with the second primary cell again.

[0154] The terminal can complete downlink synchronization with the second secondary cell (i.e., the target SCell) before receiving the MAC CE indicating the handover of the primary cell. For example, the base station can pre-configure candidate secondary cells, and the terminal performs downlink synchronization with each candidate secondary cell; the second secondary cell identifier is carried in the MAC CE, and the second secondary cell belongs to the pre-configured candidate primary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE and channel state measurement, without having to perform downlink synchronization with the second secondary cell again, thereby reducing the handover delay of the secondary cell.

[0155] Optionally, before receiving the MAC CE indicating the handover of the primary cell, the terminal can receive the SSB of the second secondary cell and perform downlink coarse synchronization operations based on the SSB. After the downlink coarse synchronization is completed, the terminal can receive the SSB, P-TRS, or A-TRS of the second secondary cell and perform downlink fine synchronization and other operations.

[0156] After receiving the MAC CE indicating the primary cell handover, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement based on the reference signal, generate channel state information and send the channel state information to the first primary cell. Among them, the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0157] The above channel state measurement can be semi-persistent measurement, that is, the base station pre-configures periodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover triggers the periodic CSI-RS resources to take effect. When the terminal receives the MAC CE, it starts to receive CSI-RS on the periodic CSI-RS resources, performs channel state measurement and reporting.

[0158] The above channel state measurement can also be aperiodic measurement, that is, the base station pre-configures aperiodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover carries an indication to trigger aperiodic CSI measurement. When the terminal receives the MAC CE, it starts to receive CSI-RS on the aperiodic CSI-RS resources, performs channel state measurement and reporting, so that the base station can obtain channel state information earlier.

[0159] After receiving the channel state information, the base station considers that the secondary cell handover is completed.

[0160] Based on Figure 8 the shown process, the start time of the handover delay of the secondary cell can be defined as the time when the terminal receives the MAC CE indicating the primary cell handover, and the end time of the handover delay of the secondary cell can be defined as the time when the terminal sends the channel state information. Among them, the handover delay of the secondary cell includes: the time for the terminal to parse the MAC CE, the time for the terminal to feedback the reception situation of the MACCE based on HARQ, and the time for the terminal to perform channel state measurement and reporting, etc. Figure 8 In it, the handover delay of the secondary cell may be greater than the handover delay of the primary cell, may be less than the handover delay of the primary cell, or may be equal to the handover delay of the primary cell.

[0161] Case 3: Downlink synchronization and channel state measurement are performed before receiving the first information.

[0162] Optionally, in method 600, the processes of primary cell handover and secondary cell handover are as Figure 9 shown. Figure 9Among them, the terminal can complete downlink synchronization and uplink synchronization with the second primary cell (i.e., the target PCell) before receiving the MAC CE indicating the primary cell handover. After receiving the MAC CE indicating the primary cell handover, the terminal performs the primary cell handover. For example, the base station can pre-configure candidate primary cells, and the terminal performs downlink synchronization and uplink synchronization with each candidate primary cell; the MAC CE carries the identifier of the second primary cell, and the second primary cell belongs to the pre-configured candidate primary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE, reconfiguring L2 / L3, baseband retuning, and radio frequency retuning, without having to perform downlink synchronization and uplink synchronization with the second primary cell again.

[0163] The terminal can complete downlink synchronization with the second secondary cell (i.e., the target SCell) before receiving the MAC CE indicating the primary cell handover. For example, the base station can pre-configure candidate secondary cells, and the terminal performs downlink synchronization with each candidate secondary cell; the MAC CE carries the identifier of the second secondary cell, and the second secondary cell belongs to the pre-configured candidate primary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE, without having to perform downlink synchronization and channel state measurement with the second secondary cell again, thereby reducing the latency of the secondary cell handover.

[0164] Optionally, before receiving the MAC CE indicating the primary cell handover, the terminal can receive the SSB of the second secondary cell and perform downlink coarse synchronization operations based on the SSB. After the downlink coarse synchronization is completed, the terminal can receive the SSB, P-TRS, or A-TRS of the second secondary cell and perform downlink fine synchronization and other operations.

[0165] Before receiving the MAC CE indicating the primary cell handover and after the downlink fine synchronization is completed, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement based on the reference signal, generate channel state information, and send the channel state information to the first primary cell, where the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0166] The above channel state measurement can be semi-persistent measurement, that is, the base station pre-configures periodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover triggers the periodic CSI-RS resources to become effective. When the terminal receives the MAC CE, it starts to receive CSI-RS on the periodic CSI-RS resources to perform channel state measurement and reporting.

[0167] The above channel state measurement can also be an aperiodic measurement. That is, the base station pre-configures aperiodic CSI-RS resources in advance, and the MAC CE indicating the primary cell handover carries an indication for triggering aperiodic CSI measurement. When the terminal receives this MAC CE, it starts to receive CSI-RS on the aperiodic CSI-RS resources, performs channel state measurement and reporting, so that the base station can obtain channel state information earlier.

[0168] After receiving the channel state information, the base station considers that the secondary cell handover is completed.

[0169] Based on Figure 9 The flow shown, the start time of the handover delay of the secondary cell can be defined as the time when the terminal receives the MAC CE indicating the primary cell handover, and the end time of the handover delay of the secondary cell can be defined as the time when the terminal sends the channel state information. Among them, the handover delay of the secondary cell includes: the time for the terminal to parse the MAC CE, and the time for the terminal to feedback the reception situation of the MAC CE based on HARQ, etc. Figure 9 In, the handover delay of the secondary cell may be greater than, less than, or equal to the handover delay of the primary cell.

[0170] Optionally, in method 600, before receiving the first information, the terminal can also perform the following steps:

[0171] Send a second information, and the second information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover.

[0172] Simultaneous primary cell handover and secondary cell handover requires the support of the terminal's capabilities. Some terminals may not have this capability. Therefore, after the terminal reports in advance that it has the capability to perform primary cell handover and secondary cell handover simultaneously, and then performs secondary cell handover based on the first information, it can avoid the failure of secondary cell handover due to lack of this capability. For example, if the terminal does not have the capability to perform primary cell handover and secondary cell handover simultaneously and the terminal does not report the second information, the base station may default that the terminal has the capability to perform primary cell handover and secondary cell handover simultaneously. After the base station sends the primary cell handover signaling, it no longer sends the secondary cell activation signaling, then the terminal cannot complete the activation of the secondary cell and cannot communicate on the target secondary cell.

[0173] The second information can be indicated in an explicit manner or an implicit manner. When using the explicit manner, the second information can include a dedicated field, such as a third field. When the value of the third field is "1", it indicates that the terminal supports simultaneous primary cell handover and secondary cell handover. When the value of the third field is "0", it indicates that the terminal does not support simultaneous primary cell handover and secondary cell handover. When using the implicit manner, the second information can reuse some fields for indication. The second information can reuse some information formats or information types for indication. For example, when the format of a certain information sent by the terminal to the base station is format A, it indicates that the terminal supports simultaneous primary cell handover and secondary cell handover. When the format of a certain information sent by the terminal to the base station is format B, it indicates that the terminal does not support simultaneous primary cell handover and secondary cell handover.

[0174] The embodiments of the present application do not limit the specific form of the second information and the sending manner of the second information.

[0175] After the terminal sends the second information, the base station can process according to the content indicated by the second information. For example, when the second information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover, the base station can configure the resources required for secondary cell handover for the terminal before sending the first information, such as the downlink synchronization resources and / or channel state measurement resources of the secondary cell.

[0176] Optionally, the terminal can further report whether it supports early secondary cell downlink synchronization and / or secondary cell channel state measurement. If the terminal supports early secondary cell downlink synchronization (or, the terminal supports secondary cell downlink synchronization before receiving the first information, or, the terminal supports secondary cell downlink synchronization when the secondary cell is in the deactivated state), the base station can configure the resources required for secondary cell downlink synchronization for the terminal before sending the first information (such as the configuration parameters of the SSB); if the terminal supports early channel state measurement (or, the terminal supports secondary cell channel state measurement before receiving the first information, or, the terminal supports secondary cell channel state measurement when the secondary cell is in the deactivated state), the base station can configure the resources required for secondary cell channel state measurement for the terminal before sending the first information (such as the configuration parameters of the CSI-RS).

[0177] The above describes the example of handover of 2 secondary cells, but the application scenario of method 600 is not limited to this, and method 600 can also be applied to the scenario of handover of more secondary cells.

[0178] For example, the serving cell of the terminal further includes a third secondary cell, and the first information may further include the identifier of the fourth secondary cell. After receiving the first information, the terminal determines to switch from the first secondary cell and the third secondary cell to the second secondary cell and the fourth secondary cell. The switching of multiple secondary cells can be performed simultaneously or separately. That is to say, the terminal can simultaneously perform the operation of switching from the first secondary cell to the second secondary cell and the operation of switching from the third secondary cell to the fourth secondary cell; or, the terminal can first perform the operation of switching from the first secondary cell to the second secondary cell, and then perform the operation of switching from the third secondary cell to the fourth secondary cell; or, the terminal can first perform the operation of switching from the third secondary cell to the fourth secondary cell, and then perform the operation of switching from the first secondary cell to the second secondary cell.

[0179] Optionally, the first information further includes the identifier of the second primary cell, and the identifier of the second primary cell is the same as the identifier of the first primary cell.

[0180] When the identifier of the second primary cell is the same as the identifier of the first primary cell, the terminal can be understood as not needing to perform primary cell switching and only performing secondary cell switching.

[0181] As Figure 10 shown, the terminal currently uses 2 carriers (CC1 and CC2) for communication. Among them, the cell corresponding to CC1 is the PCell, and the cell corresponding to CC2 is the SCell. The terminal also supports communication using CC3 and CC4, but CC3 and CC4 are not activated, and the cells corresponding to CC3 and CC4 are non-serving cells. As the terminal moves, the channel state of CC2 deteriorates. The terminal can use CC1 and CC4 for communication and no longer use CC1 and CC2 for communication. For example, the base station sends the first information to the terminal. The first information includes the identifier of the second primary cell and the identifier of the second secondary cell. Among them, the identifier of the second secondary cell is the cell identifier corresponding to CC4, and the identifier of the second primary cell is the cell identifier corresponding to CC1 (that is, the identifier of the current source PCell). After receiving the first information, the terminal obtains the identifier of the second primary cell from the first information, determines that the identifier of the second primary cell is the same as the cell identifier corresponding to CC1, and then determines not to perform primary cell switching and only perform secondary cell switching. After the cell switching is completed, the PCell is still the cell corresponding to CC1, and the SCell becomes the cell corresponding to CC4. In this way, the function of separately switching the secondary cell can be realized without changing the existing primary cell switching process, and it has better forward compatibility.

[0182] Figure 11 Another method for switching cells provided by the embodiments of the present application is that method 1100 includes:

[0183] S1110, the terminal receives the third information, and the third information instructs the terminal to switch the secondary cell from the first secondary cell to the second secondary cell.

[0184] Accordingly, the base station generates and sends third information.

[0185] In various embodiments of the present application, "the third information instructs the terminal to switch the secondary cell from the first secondary cell to the second secondary cell" can also be expressed as: the third information instructs the terminal to perform transmission on the second secondary cell. Accordingly, for the terminal or the base station, "switching the secondary cell from the first secondary cell to the second secondary cell" can be expressed as: performing transmission on the second secondary cell.

[0186] In various embodiments of the present application, "the third information instructs the terminal to switch the secondary cell from the first secondary cell to the second secondary cell" can also be expressed as: the third information instructs the terminal to change the secondary cell to the second secondary cell. Accordingly, for the terminal or the base station, "switching the secondary cell from the first secondary cell to the second secondary cell" can be expressed as: changing the secondary cell to the second secondary cell. Herein, "changing" can be interpreted as "switching".

[0187] The third information may be information generated and sent by the base station corresponding to the primary cell. The third information may be an RRC message, a MAC CE, or a DCI. The third information may also be a field in an RRC message, a MAC CE, or a DCI.

[0188] The third information may be indicated in an explicit manner or in an implicit manner. When using the explicit manner, the third information may include a dedicated field, such as a fourth field. When the value of the fourth field is "1", the fourth field combined with the identifier of the second secondary cell instructs the terminal to switch from the first secondary cell to the second secondary cell. Herein, the identifier of the second secondary cell may be sent to the terminal alone or together with the second field; when the value of the fourth field is "0", it instructs the terminal not to perform secondary cell switching. When using the implicit manner, the third information may reuse some fields for indication. For example, the MAC CE may include the identifier of the second secondary cell, and the identifier of the second secondary cell indicates the target SCell. The third information may reuse the identifier of the second secondary cell. When the terminal receives the identifier of the second secondary cell, the terminal determines to perform secondary cell switching and determines that the target SCell is the second secondary cell.

[0189] Embodiments of the present application do not limit the specific form of the third information and the sending manner of the third information.

[0190] Before sending the third message, the base station may configure a set of candidate cells, which includes at least one candidate primary cell and / or at least one candidate secondary cell. Alternatively, the base station may configure two sets of candidate cells, where one set of candidate cells includes at least one candidate primary cell and the other set of candidate cells includes at least one candidate secondary cell. Taking the latter case as an example, the base station may configure, for the terminal, a set of candidate secondary cells including 4 cells through an RRC message. The 4 cells are Cell 1, Cell 2, Cell 3, and Cell 4 respectively. If the identifier of the second secondary cell carried in the third message is the identifier of Cell 4, the terminal may determine that the second secondary cell is Cell 4. By pre-configuring the set of candidate secondary cells in this way, the base station may configure some parameters of the target secondary cell for the terminal in advance, reducing the delay of secondary cell handover.

[0191] After receiving the third message, the terminal may perform the following steps.

[0192] S1120, switch the secondary cell from the first secondary cell to the second secondary cell according to the third message.

[0193] Before the terminal switches to the second secondary cell, operations such as downlink synchronization and channel state measurement need to be performed. The terminal may obtain the measurement configuration of the second secondary cell, such as SMTC, from the primary cell before receiving the third message, and then receive the downlink synchronization signal (such as, SSB) of the second secondary cell based on the measurement configuration of the second secondary cell, and perform operations such as downlink synchronization according to the downlink synchronization signal. Performing downlink synchronization may be to perform cell search to obtain the time-frequency synchronization of the second secondary cell.

[0194] During the cell handover process, the C-RNTI assigned by the base station to the terminal needs to be updated. For example, during the handover from the first secondary cell to the second secondary cell, the C-RNTI of the terminal needs to be updated from the first C-RNTI (the C-RNTI assigned by the first secondary cell to the terminal) to the second C-RNTI (the C-RNTI assigned by the second secondary cell to the terminal). One implementation method is: each candidate secondary cell assigns a C-RNTI to the terminal, and the base station may send the C-RNTIs assigned by all candidate secondary cells to the terminal to the terminal through an RRC message before sending the third message; another implementation method is: the third message carries the C-RNTI assigned by the target secondary cell to the terminal. Since the number of C-RNTIs carried in the third message is less than the number of C-RNTIs carried in the RRC message, the latter implementation method reduces the signaling overhead caused by updating the C-RNTI compared with the former implementation method.

[0195] In method 1100, the handover process of the secondary cell is decoupled from the handover process of the primary cell. The terminal performs the handover of the secondary cell according to the indication of the third information, without caring about whether the primary cell is handed over. Compared with the method of activating the secondary cell after waiting for the handover of the primary cell to complete, method 1100 can reduce the latency of the secondary cell handover. The changes in the cells before and after the terminal executes method 1100 can be referred to Figure 10 as shown.

[0196] It should be noted that some concepts in method 1100 are the same as some concepts in method 600, and the meanings of these same concepts are the same. For example, the identifier of the second secondary cell in method 1100 is the same as the identifier of the second secondary cell in method 600, and the meaning of the identifier of the second secondary cell in method 1100 can follow the meaning of the identifier of the second secondary cell in method 600. In the following text, the meanings of concepts such as "reference signal of the second secondary cell" and "channel state measurement" can also follow the meanings of the corresponding concepts in method 600, and the meanings of these same concepts will not be elaborated.

[0197] The handover of the secondary cell includes operations such as downlink synchronization and channel state measurement. Among them, downlink synchronization and channel state measurement can be performed before receiving the third information, or can be performed after receiving the third information. Different situations are introduced in detail below. It should be noted that the various operations (such as synchronization, channel measurement, etc.) mentioned in the embodiments of the present application and the execution order of the various operations are examples rather than limitations. The handover of the secondary cell may also include other operations, and the embodiments of the present application do not limit the specific operations in the handover process of the secondary cell.

[0198] Situation 4: Downlink synchronization and channel state measurement are performed after receiving the third information.

[0199] Optionally, in method 1100, the process of the handover of the secondary cell is as Figure 12 shown. Figure 12 After the terminal receives the MAC CE indicating the handover of the secondary cell (an example of the third information), it can receive the SSB, P-TRS or A-TRS of the second secondary cell (i.e., the target SCell), and perform operations such as AGC and downlink synchronization. During the downlink synchronization process, the terminal can first perform coarse synchronization and then perform fine synchronization.

[0200] After the downlink synchronization is completed, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement according to the reference signal, generate channel state information and send the channel state information to the primary cell. Among them, the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0201] After the base station receives the channel state information, it considers that the handover of the secondary cell is completed.

[0202] Based onFigure 12 For the process shown, the start time of the handover delay of the secondary cell can be defined as the time when the terminal receives the MAC CE indicating the handover of the secondary cell, and the end time of the handover delay of the secondary cell can be defined as the time when the terminal sends the channel state information. Among them, the handover delay of the secondary cell includes: the time for the terminal to parse the MAC CE, the time for the terminal to feedback the MAC CE reception situation based on HARQ, the time for the terminal to perform downlink synchronization based on the SSB or A-TRS, and the time for the terminal to perform channel state measurement and reporting, etc.

[0203] Case 5: Downlink synchronization is performed before receiving the third information, and channel state measurement is performed after receiving the third information.

[0204] Optionally, in method 1100, the process of secondary cell handover is as Figure 13 shown. Figure 13 In this case, the terminal can complete downlink synchronization with the second secondary cell (i.e., the target SCell) before receiving the MAC CE indicating the handover of the secondary cell. For example, the base station can pre-configure candidate secondary cells, and the terminal performs downlink synchronization with each candidate secondary cell; the MAC CE carries the identifier of the second secondary cell, and the second secondary cell belongs to the pre-configured candidate secondary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE and channel state measurement, without having to perform downlink synchronization with the second secondary cell, thereby reducing the handover delay of the secondary cell.

[0205] Optionally, before receiving the MAC CE indicating the handover of the secondary cell, the terminal can receive the SSB of the second secondary cell and perform downlink coarse synchronization operations according to the SSB. After the downlink coarse synchronization is completed, the terminal can receive the SSB, P-TRS or A-TRS of the second secondary cell and perform operations such as downlink fine synchronization.

[0206] After receiving the MAC CE indicating the handover of the secondary cell, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement according to the reference signal, generate channel state information and send the channel state information to the primary cell. Among them, the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0207] After receiving the channel state information, the base station considers that the secondary cell handover is completed.

[0208] Based on Figure 13For the process shown, the start time of the secondary cell handover delay can be defined as the time when the terminal receives the MAC CE indicating the secondary cell handover, and the end time of the secondary cell handover delay can be defined as the time when the terminal transmits the channel state information. Among them, the secondary cell handover delay includes: the time for the terminal to parse the MAC CE, the time for the terminal to feedback the MAC CE reception situation based on HARQ, and the time for the terminal to perform channel state measurement and reporting, etc.

[0209] Case 6: Downlink synchronization and channel state measurement are performed before receiving the third information.

[0210] Optionally, in method 1100, the process of secondary cell handover is as Figure 14 shown. Figure 14 In it, the terminal can complete the downlink synchronization with the second secondary cell (i.e., the target SCell) before receiving the MAC CE indicating the secondary cell handover. For example, the base station can pre-configure candidate secondary cells, and the terminal performs downlink synchronization with each candidate secondary cell; the second secondary cell identifier is carried in the MAC CE, and the second secondary cell belongs to the pre-configured candidate secondary cells. After receiving the MAC CE, the terminal can directly perform steps such as parsing the MAC CE without performing downlink synchronization and channel state measurement with the second secondary cell again, thereby reducing the secondary cell handover delay.

[0211] Optionally, before receiving the MAC CE indicating the secondary cell handover, the terminal can receive the SSB of the second secondary cell and perform downlink coarse synchronization operations according to the SSB. After the downlink coarse synchronization is completed, the terminal can receive the SSB, P-TRS or A-TRS of the second secondary cell to perform downlink fine synchronization and other operations.

[0212] Before receiving the MAC CE indicating the secondary cell handover and after the downlink fine synchronization is completed, the terminal can receive the reference signal of the second secondary cell, perform channel state measurement according to the reference signal, generate channel state information and send the channel state information to the primary cell. Among them, the reference signal is, for example, CSI-RS, and the channel state information is, for example, CSI.

[0213] After receiving the channel state information, the base station considers that the secondary cell handover is completed.

[0214] Based on Figure 14 For the process shown, the start time of the secondary cell handover delay can be defined as the time when the terminal receives the MAC CE indicating the secondary cell handover, and the end time of the secondary cell handover delay can be defined as the time when the terminal transmits the channel state information. Among them, the secondary cell handover delay includes: the time for the terminal to parse the MAC CE, and the time for the terminal to feedback the MAC CE reception situation based on HARQ, etc.

[0215] The method examples provided by the embodiments of the present application are introduced in detail above. It can be understood that, correspondingly, in order for the device to implement the above functions, it includes the corresponding hardware structure and / or software module for executing each function. Those skilled in the art should easily realize that, combining the units and algorithm steps of each example described in the embodiments disclosed in this article, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the way of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0216] Figure 15 and Figure 16 are schematic structural diagrams of two possible communication devices provided by the embodiments of the present application. These communication devices can be used to implement the functions of the terminal or the base station in the above method embodiments, and thus also have the beneficial effects possessed by the above method embodiments. In the embodiments of the present application, these communication devices can be Figure 1 the terminal shown in Figure 1 the base station described above, or can also be a module (such as a chip) applied to the terminal or the base station.

[0217] As Figure 15 shown, the communication device 1500 includes a processing unit 1510 and a transceiver unit 1520. The transceiver unit 1520 executes the receiving step and / or the sending step under the control of the processing unit 1510. Among them, when the transceiver unit 1520 executes the sending step, it is a sending unit, and when the transceiver unit 1520 executes the receiving step, it is a receiving unit. The communication device 1500 is used to implement the functions of the terminal or the base station in the above Figure 6 or Figure 11 described method embodiments.

[0218] When the communication device 1500 is used to implement the function of the terminal in the Figure 6 described method embodiment, the transceiver unit 1520 is used to: receive first information, the first information indicating that the terminal switches the primary cell from the first primary cell to the second primary cell, and the first information includes the identifier of the second secondary cell; the processing unit 1510 is used to: switch the primary cell from the first primary cell to the second primary cell according to the first information, and switch the secondary cell from the first secondary cell to the second secondary cell.

[0219] Optionally, before switching from the first secondary cell to the second secondary cell according to the first information, the transceiver unit 1520 is further used to: receive the downlink synchronization signal of the second secondary cell; the processing unit 1510 is further used to: perform cell search according to the downlink synchronization signal to obtain the time-frequency synchronization of the second secondary cell.

[0220] Optionally, the processing unit 1510 is specifically configured to: before the transceiver unit 1520 receives the first information, perform cell search according to the downlink synchronization signal to obtain the time-frequency synchronization of the second secondary cell.

[0221] Optionally, before switching from the first secondary cell to the second secondary cell according to the first information, the transceiver unit 1520 is further configured to: receive the reference signal of the second secondary cell; send the channel state information, where the channel state information is determined by the processing unit 1510 based on the reference signal.

[0222] Optionally, the transceiver unit 1520 is specifically configured to: send the channel state information before receiving the first information.

[0223] Optionally, before receiving the first information, the transceiver unit 1520 further includes: sending the second information, where the second information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover.

[0224] When the communication device 1500 is used to implement Figure 6 the functions of the base station in the method embodiment described above, the transceiver unit 1520 is configured to: send the first information, where the first information indicates that the terminal switches the primary cell from the first primary cell to the second primary cell, the first information includes the identifier of the second secondary cell, and the first information further indicates that the terminal switches the secondary cell from the first secondary cell to the second secondary cell, and the first primary cell and the first secondary cell are the serving cells of the terminal; the processing unit 1510 is configured to: switch the primary cell from the first primary cell to the second primary cell, and switch the secondary cell from the first secondary cell to the second secondary cell.

[0225] Optionally, the transceiver unit 1520 is further configured to: send the downlink synchronization signal of the second secondary cell.

[0226] Optionally, the transceiver unit 1520 is specifically configured to: send the downlink synchronization signal of the second secondary cell before sending the first information.

[0227] Optionally, the transceiver unit 1520 is further configured to: send the reference signal of the second secondary cell; receive the channel state information, where the channel state information is determined based on the reference signal.

[0228] Optionally, the transceiver unit 1520 is specifically configured to: send the reference signal of the second secondary cell before sending the first information.

[0229] Optionally, before the processing unit 1510 sends the first information, the transceiver unit 1520 is further configured to: receive the second information, where the second information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover.

[0230] When the communication device 1500 is used to implement Figure 11When implementing the functions of the terminal in the method embodiments described above, the transceiver unit 1520 is configured to: receive third information, where the third information indicates that the terminal switches the secondary cell from the first secondary cell to the second secondary cell; the processing unit 1510 is configured to: switch the secondary cell from the first secondary cell to the second secondary cell according to the third information.

[0231] Optionally, before switching the secondary cell from the first secondary cell to the second secondary cell according to the third information, the transceiver unit 1520 is further configured to: receive the downlink synchronization signal of the second secondary cell; the processing unit 1510 is further configured to: perform cell search according to the downlink synchronization signal to obtain the time-frequency synchronization of the second secondary cell.

[0232] Optionally, the transceiver unit 1520 is specifically configured to: receive the downlink synchronization signal of the second secondary cell before receiving the third information.

[0233] Optionally, before switching the secondary cell from the first secondary cell to the second secondary cell according to the third information, the transceiver unit 1520 is further configured to: receive the reference signal of the second secondary cell; send channel state measurement information, where the channel state measurement information is determined by the processing unit 1510 based on the reference signal.

[0234] Optionally, the transceiver unit 1520 is specifically configured to: receive the reference signal of the second secondary cell before receiving the third information.

[0235] When the communication device 1500 is used to implement Figure 11 the functions of the base station in the method embodiments described above, the transceiver unit 1520 is configured to: send third information, where the third information indicates that the terminal switches the secondary cell from the first secondary cell to the second secondary cell; the processing unit 1510 is configured to: switch the secondary cell from the first secondary cell to the second secondary cell.

[0236] Optionally, the transceiver unit 1520 is further configured to: send the downlink synchronization signal of the second secondary cell.

[0237] Optionally, the transceiver unit 1520 is specifically configured to: send the downlink synchronization signal of the second secondary cell before sending the third information.

[0238] Optionally, the transceiver unit 1520 is further configured to: send the reference signal of the second secondary cell; receive channel state measurement information, where the channel state measurement information is determined based on the reference signal.

[0239] Optionally, the transceiver unit 1520 is specifically configured to: send the reference signal of the second secondary cell before sending the third information.

[0240] Those skilled in the art can clearly understand that when the communication device 1500 is used to implement the functions of a terminal or a base station, the specific working process of the communication device 1500 and the technical effects generated by the execution steps can refer to the descriptions in the corresponding method embodiments described above. For the sake of brevity, they will not be repeated here.

[0241] The communication device 1500 can be a terminal or a base station. The processing unit 1510 can be implemented by hardware or by software. When implemented by hardware, the processing unit 1510 can be a logic circuit, an integrated circuit, etc.; when the processing unit 1510 is implemented by software, the processing unit 1510 can be a general-purpose processor, which is implemented by reading the software code stored in the storage unit. The storage unit can be integrated in the processing unit 1510 or can exist independently outside the processing unit 1510.

[0242] As Figure 16 shown, the communication device 1600 includes a processor 1610 and an interface circuit 1620. The processor 1610 and the interface circuit 1620 are coupled to each other. It can be understood that the interface circuit 1620 can be a transceiver or an input / output interface. Optionally, the communication device 1600 may further include a memory 1630, which is used to store the instructions executed by the processor 1610 or the input data required for the processor 1610 to run the instructions or the data generated after the processor 1610 runs the instructions.

[0243] When the communication device 1600 is used to implement Figure 6 or Figure 11 the method shown, the processor 1610 is used to implement the functions of the above-mentioned processing unit 1610, and the interface circuit 1620 is used to implement the functions of the above-mentioned transceiver unit 1620.

[0244] When the communication device 1600 is a terminal chip (i.e., a chip applied to a terminal), the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from the base station. It can be understood that the information is first received by other modules (such as a radio frequency module or an antenna) in the terminal and then sent to the terminal chip by these modules. The terminal chip sends information to the base station. It can be understood that the information is first sent to other modules (such as a radio frequency module or an antenna) in the terminal and then sent to the base station by these modules.

[0245] When the communication device 1600 is a base station chip (i.e., a chip applied to a base station), the base station chip implements the functions of the base station in the above method embodiments. The base station chip receives information from a terminal. It can be understood that this information is first received by other modules (such as a radio frequency module or an antenna) in the base station and then sent by these modules to the base station chip. The base station chip sends information to the terminal. It can be understood that this information is sent to other modules (such as a radio frequency module or an antenna) in the base station and then sent by these modules to the terminal.

[0246] In this application, entity A sending information to entity B can be that A directly sends to B or A indirectly sends to B through other entities. Similarly, entity B receiving information from entity A can be that entity B directly receives the information sent by entity A or entity B indirectly receives the information sent by entity A through other entities. Here, entity A and B can be RAN nodes or terminals, or modules inside RAN nodes or terminals. The sending and receiving of information can be the information interaction between a RAN node and a terminal. For example, the information interaction between a base station and a terminal; the sending and receiving of information can also be the information interaction between two RAN nodes. For example, the information interaction between a CU and a DU; the sending and receiving of information can also be the information interaction between different modules within a device. For example, the information interaction between a terminal chip and other modules of the terminal, or the information interaction between a base station chip and other modules in the base station.

[0247] It can be understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0248] The method steps in the embodiments of the present application can be implemented in hardware or in software instructions executable by a processor. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a removable hard disk, a compact disc read-only memory (CD-ROM), or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. Additionally, the ASIC can be located in a base station or a terminal. The processor and the storage medium can also exist as discrete components in a base station or a terminal.

[0249] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable devices. The computer program or instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrating one or more available media. The available medium can be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it can also be an optical medium, such as a digital video disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or can include both volatile and non-volatile types of storage media.

[0250] Finally, the following points are noted regarding the embodiments of the present application:

[0251] First, in the embodiments of the present application, the first, second, and various numerical numbers are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. For example, the primary cell 1 and the primary cell 2 represent two primary cells, and these two primary cells may be two different cells or the same cell.

[0252] Second, in the embodiments of the present application, "indicating" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a certain piece of information is called the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated. For example, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated, etc. It is also possible to indirectly indicate the information to be indicated by indicating other information, where there is an association relationship between the other information and the information to be indicated. It is also possible to only indicate a part of the information to be indicated, while the other parts of the information to be indicated are known or pre-agreed. For example, it is possible to implement the indication of the information to be indicated by relying on a pre-agreement (such as protocol regulations) on the existence of a certain cell, thereby reducing the indication overhead to a certain extent.

[0253] Third, the "protocol" involved in the embodiments of the present application may refer to the standard protocols in the communication field. For example, it may include the LTE protocol, the NR protocol, and the relevant protocols in future communication systems. The present application does not limit this.

[0254] Fourth, "predefined" or "preconfigured" can be implemented by pre-saving the corresponding codes, tables, or other means that can indicate relevant information in a device (such as a terminal or a base station). The present application does not limit the specific implementation method. Herein, "saving" may mean saving in one or more memories, and the one or more memories may be separately provided or integrated in a processor or a communication device; the one or more memories may also be partially separately provided and partially integrated in a processor or a communication device. The type of the memory may be any form of storage medium, and the present application does not limit this.

[0255] Fifth, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, or both A and B exist simultaneously. Here, A and B can be single objects or multiple objects. The character " / " generally indicates an "or" relationship between the associated objects before and after. "At least one (item)" or a similar expression refers to any combination of these items, including any combination of single item(s) or multiple item(s). For example, at least one (item) among a, b, and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b, and c. Here, a, b, and c can be single objects or multiple objects respectively.

[0256] Sixth, in the embodiments of the present application, descriptions such as "when...", "in the case of...", "if", and "when" all mean that the device (e.g., a terminal or a base station) will perform corresponding processing under a certain objective situation, rather than limiting the time. It does not require the device to have a judgment action during implementation, nor does it mean the existence of other limitations.

[0257] Seventh, in each embodiment of the present application, if there is no special description and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be mutually referred to. The technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

Claims

1. A method for cell handover, characterized in that, the method is applied to a terminal, and the serving cell of the terminal includes a first primary cell and a first secondary cell, and the method includes: receiving first information, where the first information indicates that the terminal is to hand over the primary cell from the first primary cell to a second primary cell, and the first information includes an identifier of a second secondary cell; handing over the primary cell from the first primary cell to the second primary cell according to the first information, and handing over the secondary cell from the first secondary cell to the second secondary cell.

2. The method according to claim 1, characterized in that, the method further includes: receiving a downlink synchronization signal of the second secondary cell; performing cell search according to the downlink synchronization signal to obtain time-frequency synchronization of the second secondary cell.

3. The method according to claim 2, characterized in that, the performing cell search according to the downlink synchronization signal to obtain time-frequency synchronization of the second secondary cell includes: before receiving the first information, performing cell search according to the downlink synchronization signal to obtain time-frequency synchronization of the second secondary cell.

4. The method according to any one of claims 1 to 3, characterized in that, the method further includes: receiving a reference signal of the second secondary cell; sending channel state information, where the channel state information is determined based on the reference signal.

5. The method according to claim 4, characterized in that, the sending the channel state information includes: before receiving the first information, sending the channel state information.

6. The method according to any one of claims 1 to 5, characterized in that, the method further includes: sending second information, where the second information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover.

7. The method according to any one of claims 1 to 6, characterized in that, the first information further includes an identifier of the second primary cell, and the identifier of the second primary cell is the same as the identifier of the first primary cell.

8. A method for cell handover, characterized in that, the method includes: sending first information, where the first information indicates that a terminal is to hand over the primary cell from a first primary cell to a second primary cell, the first information includes an identifier of a second secondary cell, and the first information further indicates that the terminal is to hand over the secondary cell from a first secondary cell to the second secondary cell, and the first primary cell and the first secondary cell are serving cells of the terminal; handing over the primary cell from the first primary cell to the second primary cell, and handing over the secondary cell from the first secondary cell to the second secondary cell.

9. The method according to claim 8, characterized in that, the method further includes: sending a downlink synchronization signal of the second secondary cell.

10. The method according to claim 9, characterized in that, the sending the downlink synchronization signal of the second secondary cell includes: before sending the first information, sending the downlink synchronization signal of the second secondary cell.

11. The method according to any one of claims 8 to 10, characterized in that, the method further includes: sending a reference signal of the second secondary cell; Receive channel state information, where the channel state information is determined based on the reference signal.

12. The method according to claim 11, wherein, sending the reference signal of the second secondary cell includes: Before sending the first information, send the reference signal of the second secondary cell.

13. The method according to any one of claims 8 to 12, wherein, the method further includes: Receive a second piece of information, where the second piece of information indicates that the terminal supports simultaneous primary cell handover and secondary cell handover.

14. The method according to any one of claims 8 to 13, wherein, the first information further includes an identifier of the second primary cell, and the identifier of the second primary cell is the same as the identifier of the first primary cell.

15. A communication device, wherein, comprising: A processor and an interface circuit, where the interface circuit is configured to receive signals from other communication devices and transmit them to the processor or send signals from the processor to other communication devices, and the processor is configured to implement the method according to any one of claims 1 to 7 through logic circuits or by executing code instructions, or to implement the method according to any one of claims 8 to 14.

16. A computer-readable storage medium, wherein, the computer-readable storage medium stores a computer program or instructions, and when the computer program or instructions are executed by a communication device, the method according to any one of claims 1 to 7 is implemented, or the method according to any one of claims 8 to 14 is implemented.

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