WO2020155073A1 - 一种小区切换的方法及装置 - Google Patents

一种小区切换的方法及装置 Download PDF

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Publication number
WO2020155073A1
WO2020155073A1 PCT/CN2019/074308 CN2019074308W WO2020155073A1 WO 2020155073 A1 WO2020155073 A1 WO 2020155073A1 CN 2019074308 W CN2019074308 W CN 2019074308W WO 2020155073 A1 WO2020155073 A1 WO 2020155073A1
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Prior art keywords
cell
timer
type
target
target cell
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PCT/CN2019/074308
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English (en)
French (fr)
Inventor
唐珣
陈君
张戬
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to PCT/CN2019/074308 priority Critical patent/WO2020155073A1/zh
Publication of WO2020155073A1 publication Critical patent/WO2020155073A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point

Definitions

  • This application relates to the field of communication technologies, and in particular to a method and device for cell handover.
  • a switching of the serving cell may occur according to changes in signal strength or load balancing requirements on the network side.
  • a conditional handover technique is proposed in the prior art.
  • the source base station sends a handover command to the terminal, and the handover command indicates multiple candidate target cells and the respective handover conditions of the multiple candidate target cells.
  • the terminal After receiving the handover command sent by the source base station, the terminal will not immediately execute the handover process, but will continue to maintain the radio resource control (RRC) connection with the source base station, and measure and switch the multiple candidate target cells Evaluation of conditions. If one of the multiple candidate target cells meets the corresponding handover condition, the candidate target cell is the target cell of the terminal.
  • RRC radio resource control
  • the terminal performs the handover process from the source cell to the target cell. During the handover process, the terminal will disconnect the RRC connection with the source base station and perform a random access procedure for the target cell. After the terminal sends a handover complete message to the target cell, the terminal establishes an RRC connection with the target cell.
  • the terminal will disconnect from the source base station during the handover process until the handover is completed and the connection with the target cell is established. During this process, the terminal's data transmission is interrupted. In order to reduce the interruption time of data transmission during the handover, the prior art proposes a solution. Based on the above-mentioned conditional handover technology, the terminal continues to maintain the RRC connection with the source base station during the handover process, and continues to transmit data with the source base station until the terminal establishes an RRC connection with the target cell, so there may be simultaneous terminals during the handover process. Keeping connected with the source base station and target cell.
  • This application provides a method and device for cell handover to solve the problem of how to select a suitable target cell among multiple candidate target cells.
  • a method for cell handover is provided.
  • the subject of the method may be a terminal.
  • the method may be implemented by the following steps: the source cell indicates multiple candidate target cells to the terminal, and the terminal preferentially selects the first type according to the application scenario
  • the cell is the target cell, or the second type of cell is preferentially selected as the target cell.
  • the terminal preferentially selects the first type of cell as the target cell, it is helpful to realize the solution that the terminal maintains connection with the source cell and the target cell during the handover process.
  • the terminal preferentially selects the second type of cell as the target cell, so as to avoid the need to send indication signaling when selecting the first type of cell as the target cell, causing resource waste.
  • one or more radio resource control RRC messages are received from the source cell, the one or more RRC messages are used to indicate a plurality of candidate target cells, and the plurality of candidate target cells include cells of the first type
  • the second type of cell the first type of cell supports the common service of the terminal with the source cell during the handover, and the second type of cell does not support the common service of the terminal with the source cell during the handover
  • the first type of cell includes a first cell
  • the second type of cell includes a second cell
  • the target cell is determined according to a selection rule, wherein the selection rule includes: For the second-type cell, the first-type cell is preferentially selected as the target cell.
  • the terminal can measure and evaluate multiple candidate target cells, and the terminal independently determines the time point of cell handover, avoiding the problem of handover failure caused by sending handover commands too early or too late, which improves Reliability in the switching process.
  • the terminal prefers the first type of cell as the target cell, which can help to combine conditional handover with the eMBB solution.
  • the data transmission interruption time during the switching process is reduced.
  • the RRC message includes an RRC connection reconfiguration message, a conditional handover command, a handover command, or a candidate target cell configuration message.
  • the solution of optimizing the first type of cell as the target cell is realized through a timer.
  • the related configuration of the timer can be configured through the above RRC message.
  • the related configuration of the timer is the configuration of parameters such as timing duration and delay duration.
  • the delay time refers to a delay for a period of time before the timer is started after the switching condition is met.
  • the related configuration of the timer can also be indicated by other messages, and the default configuration can also be adopted. For example, through agreement.
  • start the first timer when the first timer is running, determine the target cell in the first type of cell; after the first timer expires, in the The target cell is determined from the first type cell and the second type cell.
  • the first type of cell can be selected as the target cell when the first timer is running.
  • the first timer when running, if the first cell meets a first handover condition, it is determined that the first cell is the target cell.
  • the first cell is determined to be the target cell, otherwise, if the second cell If the second handover condition is met, it is determined that the second cell is the target cell.
  • the first cell is the Target cell.
  • multiple RRC messages are received from a source cell, the multiple RRC messages are used to indicate the multiple candidate target cells, and the multiple RRC messages include a first RRC message and a second RRC message, The first RRC message indicates the first cell, the second RRC message indicates a third cell, and the third cell belongs to the first type cell; in response to receiving the first RRC message, start all The first timer; when the first timer is running, receive the second RRC message from the network device; in response to receiving the second RRC message, restart the first timer. Each time an RRC message containing a cell of the first type is received, the first timer is started or restarted, and the first timer is applied to all candidate target cells of the terminal.
  • multiple RRC messages are received from a source cell, the multiple RRC messages are used to indicate the multiple candidate target cells, the multiple RRC messages include a first RRC message, and the first RRC message The message indicates the first cell; in response to receiving the first RRC message, a second timer is started; while the second timer is running, the target cell is determined in the first cell, After the second timer expires, the target cell is determined in the first type cell and the second type cell. In this way, a corresponding timer can be started for each first-type cell, and the timer can be used for the first-type cell.
  • the multiple RRC messages further include a second RRC message, the second RRC message indicates a third cell, and the third cell is the first type cell; at the second timing When the device is running, receive the second RRC message from the network device; in response to receiving the second RRC message, start a third timer; at the intersection of the second timer and the third timer Within the time period, determine the target cell in the first cell and the third cell; after the second timer expires and the third timer is running, determine the target cell in the third cell The target cell; after the third timer expires, the target cell is determined in the first type cell and the second type cell.
  • This design takes into account the scenario where the cell-level timers intersect.
  • a fourth timer in response to determining that the second cell satisfies the second handover condition, start a fourth timer; while the fourth timer is running, determine the target cell in the first type of cell After the fourth timer expires, it is determined that the second cell is the target cell, where the second cell satisfies the second handover condition.
  • the timer in this design works for the second type of cell and plays a role in delaying waiting.
  • the timer is started to wait for timing, and the timer runs When the time, continue to measure each candidate target cell, after the timer expires, if the first type of cell has not been selected to meet the handover condition, then the second type of cell is taken as the target cell.
  • the fourth timer when the fourth timer is running, if it is determined that the second cell does not meet the second handover condition, the fourth timer is terminated. This design proposes a condition for the termination of the fourth timer.
  • a timer in response to determining the target cell, a timer is terminated, and the timer includes any one of a first timer, a second timer, a third timer, or a fourth timer.
  • This design proposes the termination conditions of the various timers mentioned above. During the operation of the various timers in the above examples, once the target cell is determined, the timer is terminated.
  • the first type cell and the second type cell may also have any one or more of the following features: the base station to which the first type cell belongs and the base station to which the source cell belongs have direct The base station to which the second type cell belongs does not have a direct communication interface with the base station to which the source cell belongs; the protocol version of the base station to which the first type cell belongs is the same as the base station to which the source cell belongs, and the second The protocol version of the base station to which the type cell belongs is different from that of the base station to which the source cell belongs; the first type cell supports enhanced connection maintenance eMBB technology, and the second type cell does not support the eMBB technology; the first type cell is different from The frequency of the source cell is not consistent, and the frequency of the second type cell is consistent with the frequency of the source cell.
  • the base station to which the first type cell belongs and the base station to which the source cell belongs have direct The base station to which the second type cell belongs does not have a direct communication interface with the base station to which the source cell belongs; the protocol version of the base
  • one or more radio resource control RRC messages are received from the source cell, the one or more RRC messages are used to indicate a plurality of candidate target cells, and the plurality of candidate target cells include cells of the first type
  • the second type of cell the first type of cell supports the common service of the terminal with the source cell during the handover, and the second type of cell does not support the common service of the terminal with the source cell during the handover
  • the first type of cell includes a first cell
  • the second type of cell includes a second cell
  • a target cell is determined according to a selection rule, wherein the selection rule further includes: In a scenario where a radio link failure occurs in the source cell, compared to the first type cell, the second type cell is preferentially selected as the target cell.
  • the RRC connection with the source cell is maintained, and the process of random access to the target cell is performed. It is helpful to combine conditional handover technology with eMBB scheme to achieve high reliability and zero interruption during handover.
  • the terminal can avoid random access to the target cell again.
  • the indication of the first indication message and/or the second indication message it is possible to achieve consistency between the terminal and the candidate target cells on both sides of the source cell.
  • the target cell can also be reserved, and the layer three filter of the target cell is restarted; or, the filter coefficients of the layer three filter of the target cell are updated, and the layer three is restarted Filter; or, update the filter coefficients of the layer three filter of the target cell.
  • the latest measurement result of the target cell can be obtained, and the weight of the historical measurement result of the target cell can be reduced.
  • the connection with the source cell is maintained to ensure the normal transmission of user data
  • the candidate target cell is continuously evaluated, and the next target cell is selected for random access to ensure cell handover Work properly.
  • a method for cell handover is provided.
  • the subject of the method may be a terminal.
  • the method is specifically implemented by the following steps: determining a target cell from one or more candidate target cells; maintaining radio resource control with the source cell RRC connection, perform the process of random access to the target cell; if the random access fails, then: delete the target cell from the one or more candidate target cells; or restart the target The layer three filter of the cell; or, update the filter coefficient of the layer three filter of the target cell, and restart the layer three filter; or, update the filter coefficient of the layer three filter of the target cell.
  • the target cell fails, the normal transmission of user data is ensured by maintaining the connection with the source cell, and the candidate target cell is continuously evaluated, and the next target cell is selected for random access to ensure normal cell handover.
  • a first indication message is sent to the source cell, and a second indication message is received from the source cell, where the first indication message is used to indicate that the random access fails, and the second indication The message is used to instruct to delete the target cell from the one or more candidate target cells; according to the second instruction message, the target cell is deleted from the one or more candidate target cells.
  • the terminal can avoid random access to the target cell again.
  • a first RRC message is received from the source cell, where the first RRC message is used to indicate the one or more candidate target cells.
  • the multiple candidate target cells include a first type cell, or the multiple candidate target cells include the first type cell and the second type cell, and the first type cell supports The source cell jointly serves the terminal during the handover process, the second type cell does not support the common service for the terminal with the source cell during the handover process, the first type cell includes the first cell, the The second type of cell includes the second cell.
  • the target cell is determined according to a selection rule, where the selection rule includes: preferentially selecting the first type cell as the target cell compared to the second type cell.
  • a cell handover device in a third aspect, has a function of realizing any possible design of the first aspect, the second aspect, and the first aspect, or any possible design of the second aspect.
  • the functions can be realized by hardware, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules corresponding to the above-mentioned functions.
  • the device can be a chip or an integrated circuit.
  • the device includes a transceiver and a processor, the transceiver is used to communicate with other communication devices, and the processor is used to couple with the memory to execute the program stored in the memory.
  • the device can The method described in any possible design of the first aspect, the second aspect, the first aspect, or any possible design of the second aspect is implemented.
  • the device also includes a memory for storing programs executed by the processor.
  • the device is a terminal.
  • a chip is provided, the chip is connected to a memory or the chip includes a memory, and is used to read and execute a software program stored in the memory, so as to implement the above-mentioned first, second, and first aspects.
  • a communication system in a fifth aspect, includes the device described in the third aspect.
  • a computer storage medium which stores a computer program, and the computer program includes instructions for executing the foregoing aspects and any possible design method in each aspect.
  • a computer program product containing instructions which when running on a computer, causes the computer to execute the above-mentioned aspects and the methods described in any possible design of the aspects.
  • FIG. 1 is a schematic diagram of a communication system architecture in an embodiment of the application
  • FIG. 2 is a schematic flowchart of a method for cell handover in an embodiment of the application
  • FIG. 3 is one of the schematic diagrams of the first implementation mode of the first type of cell in the embodiment of the application;
  • FIG. 4 is the second schematic diagram of the first implementation manner of the first type of cell in the embodiment of the application.
  • FIG. 5 is one of the schematic diagrams of the second implementation manner of the preferred first type cell in the embodiment of the application.
  • FIG. 6a is the second schematic diagram of the second implementation manner of the preferred first type cell in an embodiment of the application.
  • FIG. 6b is the third schematic diagram of the second implementation manner of the preferred first type cell in the embodiment of the application.
  • FIG. 7a is the fourth schematic diagram of the second implementation manner of the preferred first-type cell in an embodiment of the application.
  • FIG. 7b is the fifth schematic diagram of the second implementation manner of the preferred first-type cell in the embodiment of the application.
  • Fig. 8a is one of the schematic diagrams of the third implementation manner of the preferred first-type cell in an embodiment of the application;
  • FIG. 8b is the second schematic diagram of the third implementation manner of the preferred first type cell in the embodiment of the application.
  • FIG. 9 is a schematic diagram of a method for combining conditional handover and eMBB scheme to realize cell handover in an embodiment of the application.
  • FIG. 10 is a schematic diagram of a solution to a random access failure to a target cell in an embodiment of the application.
  • FIG. 11 is a schematic diagram of a measurement model for a terminal to measure a cell in an embodiment of the application.
  • FIG. 12 is one of the schematic structural diagrams of the cell handover apparatus in an embodiment of this application.
  • FIG. 13 is the second schematic diagram of the structure of the cell handover apparatus in an embodiment of the application.
  • the embodiments of the present application provide a method and device for cell handover, which help to solve the problem of how to select a suitable target cell among multiple candidate target cells.
  • the method and the device are based on the same concept. Since the principles of the method and the device to solve the problem are similar, the implementation of the device and the method can be referred to each other, and the repetition will not be repeated.
  • "and/or" describes the association relationship of the associated objects, indicating that there can be three types of relationships, for example, A and/or B, which can mean that there is A alone, and both A and B exist. There are three situations of B.
  • the character "/" generally indicates that the associated objects are in an "or” relationship.
  • At least one involved in this application refers to one or more; multiple involved refers to two or more.
  • words such as “first” and “second” are only used for the purpose of distinguishing description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating Or imply the order.
  • FIG. 1 shows the architecture of a possible communication system to which the method for cell handover provided by an embodiment of the present application is applicable.
  • the communication system 100 includes: the communication system 100 includes: a network device 101 and a terminal 102 .
  • the network device 101 is a device with a wireless transceiver function or a chip that can be installed in the device.
  • the device includes but is not limited to: evolved Node B (evolved Node B, eNB), radio network controller (RNC), Node B (Node B, NB), base station controller (BSC), base transceiver station (BTS), home base station (for example, home evolved NodeB, or home Node B, HNB), baseband unit (baseband unit, BBU), access point (AP), wireless relay node, wireless backhaul node, transmission point (transmission and reception point, TRP or transmission) in wireless fidelity (WIFI) systems point, TP), etc., it can also be a gNB in a 5G (such as NR) system, or a transmission point (TRP or TP), one or a group (including multiple antenna panels) antenna panels of a base station in a 5G system, or It may also be a network node that constitutes a gNB or a transmission
  • the gNB may include a centralized unit (CU) and a DU.
  • the gNB may also include a radio unit (RU).
  • CU realizes some functions of gNB
  • DU realizes some functions of gNB, for example, CU realizes radio resource control (radio resource control, RRC), packet data convergence protocol (packet data convergence protocol, PDCP) layer functions
  • DU realizes wireless link Channel control (radio link control, RLC), media access control (media access control, MAC) and physical (physical, PHY) layer functions.
  • the network device may be a CU node, or a DU node, or a device including a CU node and a DU node.
  • the CU can be divided into network equipment in the access network RAN, and the CU can also be divided into network equipment in the core network CN, which is not limited here.
  • the terminal can also be called user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile equipment, user terminal, terminal equipment, wireless communication equipment, user Agent or user device.
  • the terminal in the embodiment of the present application may be a mobile phone (mobile phone), a tablet computer (Pad), a computer with a wireless transceiver function, a virtual reality (VR) terminal device, and an augmented reality (AR) terminal device , Wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grid, transportation safety (transportation) Wireless terminals in safety), wireless terminals in smart cities, wireless terminals in smart homes, and so on.
  • the embodiment of this application does not limit the application scenario.
  • a terminal with a wireless transceiver function and a chip that can be set in the aforementioned terminal are collectively referred to as a terminal.
  • the cell handover method provided in the embodiments of this application can be applied to various communication systems, such as: long term evolution (LTE) system, worldwide interoperability for microwave access (WiMAX) communication system, fifth Generation (5th Generation, 5G) systems, such as new generation radio access technology (NR), and future communication systems, such as 6G systems.
  • LTE long term evolution
  • WiMAX worldwide interoperability for microwave access
  • 5G fifth Generation
  • NR new generation radio access technology
  • 6G systems future communication systems, such as 6G systems.
  • This application relates to the handover of a terminal from a source base station to a target base station, where the source base station and the target base station may belong to the same communication system or may belong to different communication systems.
  • the source base station and the target base station are LTE base stations, or the source base station and the target base station are NR base stations, or the source base station is an LTE base station and the target base station is an NR base station, or the source base station is an NR base station and the target base station is an LTE base station.
  • This application relates to the process of cell handover.
  • the terminal is handed over from the source cell to the target cell, and the network equipment to which the source cell belongs exchanges information or data with the terminal.
  • the network equipment to which the source cell belongs may be called the source base station.
  • the network device to which the target cell belongs may be referred to as the target base station.
  • the information/data interaction between the terminal and the source cell can be understood as the information/data interaction between the terminal and the source base station.
  • the information/data interaction between the terminal and the target cell can be understood as the information/data interaction between the terminal and the target base station.
  • the terminal handover from the source cell to the target cell can be understood as the terminal handover from connecting with the source base station to connecting with the target base station.
  • the connection may refer to a radio resource control (Radio Resource Control, RRC) connection.
  • the terminal maintains an RRC connection with the cell or base station, and can exchange information or data with the cell or base station.
  • RRC Radio Resource Control
  • the terminal of the present application may also have the ability to keep the terminal connected to both the source cell and the target cell during the handover process, until the terminal completes the random access process with the target cell before disconnecting from the source cell, or the terminal is disconnected by other trigger methods. Open the connection with the source cell.
  • This solution can be called an enhanced make before break (eMBB) solution, or a simultaneous connection switching solution, and of course it can also be called another name. It can also be called that the source cell and the target cell jointly serve the terminal during the handover process. This solution can achieve the effect of uninterrupted data transmission of the terminal during the cell handover.
  • the source base station to which the source cell belongs and the target base station to which the target cell belongs are required to meet at least one of the following conditions: the source base station and the target base station have a direct communication interface; the protocol version of the source base station and the target base station are the same; the frequency of the source cell and the target cell Inconsistent.
  • the frequency of the source cell and the target cell are required to be inconsistent, because considering the different capabilities of the terminals, some terminals cannot support the simultaneous data transmission and reception of two cells of the same frequency. Therefore, the frequency of the source cell and the target cell are required to be inconsistent to realize the eMBB solution. .
  • the above are just examples and do not constitute a limitation.
  • this application can plan candidate target cells into two types, represented by the first type of cell and the second type of cell.
  • the first type of cell supports the common service of the terminal with the source cell during the handover
  • the second type of cell does not support the common service of the terminal with the source cell during the handover.
  • the terminal refers to the terminal where the cell handover occurs.
  • the base station to which the first type cell belongs and the source base station to which the source cell belongs have a direct communication interface
  • the base station to which the second type cell belongs does not have a direct communication interface with the source base station to which the source cell belongs.
  • the protocol version of the base station to which the first type cell belongs is the same as the source base station to which the source cell belongs, and the protocol version of the base station to which the second type cell belongs and the source base station to which the source cell belongs are different.
  • the first type of cell supports the eMBB solution
  • the second type of cell does not support the eMBB solution.
  • the frequencies of the first type cell and the source cell are inconsistent, and the frequencies of the second type cell and the source cell are the same, aiming at a scenario where the terminal cannot support simultaneous data transmission and reception of two cells of the same frequency.
  • the source cell indicates multiple candidate target cells to the terminal, and the terminal preferentially selects the first type cell as the target cell or the second type cell as the target cell according to the application scenario. For example, if the terminal preferentially selects the first type of cell as the target cell, it is helpful to realize the solution that the terminal maintains a connection with the source cell and the target cell during the handover process.
  • the source cell sends one or more RRC messages to the terminal, and the terminal receives the one or more RRC messages from the source cell.
  • the RRC message may include an RRC connection reconfiguration message, a conditional handover command, a handover command, or a candidate target cell configuration message.
  • the following RRC message uses the handover command as an example to describe.
  • One or more handover commands sent by the source cell to the terminal are used to indicate multiple candidate target cells.
  • the multiple candidate target cells include a first type cell and a second type cell.
  • the explanation of the first type of cell and the second type of cell is as described above.
  • the source cell may send multiple handover commands to the terminal at intervals. For example, after the source cell sends the first handover command to the terminal, it sends the second handover command to the terminal after a period of time.
  • the candidate target cell indicated in any handover command may be one or two types of cells. Specifically, the candidate target cells indicated in any handover command may be all cells of the first type, or all cells of the second type, or may include both the first type of cells and the second type of cells.
  • the source cell may also send a handover command to the terminal, and the multiple candidate target cells indicated by the handover command include both the first type cell and the second type cell.
  • cell identification information is used in the handover command to indicate multiple candidate target cells, where the cell identification information can be any information that can be used to identify cells in the prior art, such as cell identification ( identity, ID).
  • the handover command can also indicate the handover conditions of each candidate target cell and indicate the category of each candidate target cell.
  • the category of the candidate target cell is the first category or the second category.
  • the handover command may indicate the index of the first type or the second type, or indicate the meaning of the first type of cell or the second type of cell, for example, whether to support the common service of the terminal with the source cell in the handover process.
  • the handover condition of the candidate target cell may be the same as the measurement report condition, for example, a measurement event is used to trigger the handover.
  • the terminal after receiving the handover command, the terminal will perform handover evaluation on the candidate target cell indicated in the handover command to determine whether a handover needs to be triggered.
  • the way for the terminal to determine whether the candidate target cell meets the handover condition is that the terminal determines that the handover condition is satisfied after meeting the measurement event entry condition for a period of time.
  • the measurement event can be any of the following: 1) The signal quality of the candidate target cell is better than the signal quality of the source cell by an offset value, for example, event A3: candidate target cell>source cell+3db; 2) the source cell's signal quality The signal quality is lower than threshold 1, and/or the signal quality of the candidate target cell is greater than threshold 2.
  • the switching trigger condition may also adopt other methods.
  • the handover conditions of each candidate target cell may be the same or different. If they are different, they may refer to different measurement events, such as A3 and A4 events. It may also be the same measurement event, but the threshold value or offset value is different.
  • the source cell configures multiple candidate target cells for the terminal through handover commands in advance, which can complete the candidate target cell configuration when the communication quality between the source cell and the terminal is good.
  • the terminal can select a suitable target cell from multiple candidate target cells for handover, and the terminal can also select a suitable handover opportunity, which can improve the reliability of handover.
  • the terminal determines the target cell according to the selection rule.
  • the terminal may select a target cell among multiple candidate target cells according to selection rules.
  • the selection rule may include: preferentially selecting a first-type cell as a target cell compared to a second-type cell.
  • the terminal after receiving the handover command, the terminal will evaluate the candidate target cell indicated in the handover command, and only when the measurement result of the candidate target cell meets the corresponding handover condition will it have a chance to be selected as the target cell.
  • the priority of the first type of cell is higher than the priority of the second type of cell, that is, the first type of cell is preferentially selected as the target cell.
  • multiple candidate target cells include a first cell and a second cell, where the first cell is a first type cell and the second cell is a second type cell.
  • the handover condition corresponding to the first cell is the first handover condition
  • the handover condition corresponding to the second cell is the second handover condition. It can be understood that the first cell is any cell of the first type of cell among the multiple candidate target cells, and the second cell is any cell of the second type of cell among the multiple candidate target cells.
  • a timer can be used to realize it.
  • the related configuration of any timer in the following description can be instructed through a handover command, or configured through other RRC messages.
  • the related configuration of the timer is the configuration of parameters such as timing duration and delay duration.
  • the delay time refers to a delay for a period of time before the timer is started after the switching condition is met.
  • the related configuration of the timer can also be indicated by other messages, and the default configuration can also be adopted. For example, through agreement.
  • the timer here can be recorded as the first timer. That is, the first timer is started.
  • the target cell is determined in the first type of cell, and after the first timer expires, the target cell is determined in the first type of cell and the second type of cell.
  • the terminal measures the multiple candidate target cells indicated by the handover command.
  • the first timer is running, if it is determined that the first cell of the multiple candidate target cells meets the first handover condition, the first cell is determined to be the target cell, At the same time stop the first timer.
  • the first cell determined as the target cell here may be the first type of cell that first meets the handover condition when the first timer is running, or the first cell that meets the handover condition when the first timer is running. The cell with the best channel condition among the similar cells.
  • the second type of cell can be used as the selection range of the target cell.
  • the terminal can select a target cell from any type of cell among multiple candidate target cells.
  • the cell that meets the handover condition first after the first timer expires is the target cell, and the cell with the best channel condition among the cells that meet the handover condition may also be the target cell after the first timer expires.
  • the cell of the first type cell is determined as the target cell; if the cell of the second type cell first meets the handover condition, the type is The cell of the second type of cell is determined as the target cell.
  • the first timer expires, if the first cell meets the first handover condition, the first cell is determined to be the target cell; otherwise, if the second cell meets the second handover condition, the second cell is determined to be Target cell.
  • the measurement result of the first cell and the measurement result of the second cell are obtained when the target cell is determined, and the first cell meets the first handover condition, and the second cell also meets The second handover condition was established.
  • the first cell is still determined as the target cell according to the first-type cell preference rule.
  • the terminal If the terminal receives a handover command from the source cell and determines the candidate target cell according to the handover command, the terminal starts the first timer in response to receiving the handover command.
  • the terminal receives multiple handover commands from the source cell and determines candidate target cells based on the multiple handover commands, a scenario in which the handover command is received during the running of the first timer may occur.
  • the multiple handover commands include the first handover command and the second handover command
  • the first handover command is before the second handover command
  • the cells indicated by the first handover command and the second handover command all include the first type of cell
  • the first timer in response to receiving the first switching command, the first timer is started; while the first timer is running, the second switching command is received from the network device, and the second switching command is restarted in response to receiving the second switching command.
  • the first timer is started if the second handover command is received from the network device after the first timer expires, the first timer is still restarted.
  • the selection rule for the target cell after the first timer is running is as described above.
  • the first timer is started when the first handover command is received. It is assumed that the first timer in the multiple cells indicated by the first handover command is Cell0 and cell1 are cells of the first type, and the terminal selects the target cell in the preferred set ⁇ cell0, cell1 ⁇ . When the first timer is running, the cells in the ⁇ cell0, cell1 ⁇ set meet the handover conditions and are selected as the target cell. When the first timer is running, and the second handover command is received from the network device, and cell3 in the cell indicated in the second handover command is also a first-type cell, the terminal adds cell3 to the preferred set and restarts the first Timer.
  • the terminal selects the target cell in the preferred set ⁇ cell0, cell1, cell3 ⁇ .
  • the cells in the ⁇ cell0, cell1, cell3 ⁇ set meet the handover conditions and are selected as target cells.
  • the first timer can be understood as a terminal-level timer.
  • the effect is the same for different cells.
  • the timer may also be cell-level, and the cell-level timer has an effect on the corresponding cell, as described in the second implementation manner.
  • the timer is for one or more cells.
  • the timer is running, only the cell corresponding to the timer is allowed to be selected as the target cell. After the timer expires, it is allowed to select the cell other than that corresponding to the timer. The cell outside the cell is the target cell.
  • the terminal receives a first handover command, and the first handover command indicates one or more cells of the first type.
  • the first handover command indicates one or more cells of the first type.
  • the terminal in response to receiving the first handover command, the terminal starts a timer for timing the first cell. For distinguishing description, it is recorded as the second timer here. While the second timer is running, the target cell is determined in the first cell. When the first cell meets the first handover condition, the first cell is determined to be the target cell, and the second timer is stopped at the same time. After the first timer expires, the protection of the priority selection of the first cell becomes invalid, and the target cell can be selected from the range of all candidate target cells, that is, the target cell is selected from the first type of cell and the second type of cell.
  • the first cell is the first type cell indicated by the first handover command.
  • the first cell is any one of the multiple cells of the first type indicated by the first handover command.
  • corresponding timers may be respectively set for the multiple first-type cells indicated by the first handover command, and the timing duration of the multiple timers may be the same or different. Since the timers of the multiple first-type cells are started when the first handover command is received, in an optional manner, the same timing may be set for multiple first-type cells indicated by the first handover command. Device. Assuming that the timing duration of multiple timers is the same, regardless of whether multiple timers or one timer are set, they are all recorded as the second timer.
  • the target cell is selected from the class of cells, and after the second timer expires, the target cell is selected from the range of all candidate target cells.
  • the second timer selects the cell that preferentially meets the handover condition among the multiple cells of the first type indicated by the first handover command as the target cell, or when the second timer is running, select the first Among the multiple first-type cells indicated by the handover command, the cell that meets the handover condition and has the best channel condition is the target cell.
  • cells other than the multiple cells of the first type indicated by the first handover command are allowed to serve as target cells.
  • the first cell is determined as the target cell, and if the handover condition is satisfied first except for the second cell, then The second cell is determined as the target cell, and the second cell is any candidate target cell except the first cell.
  • the first handover command indicating multiple cells of the first type as an example.
  • the second timer expires, if the cell of the multiple first type cells first meets the handover condition, the cell that meets the handover condition is determined as the target cell If the second cell first satisfies the handover condition, the second cell is determined as the target cell, and the second cell is any candidate target cell except for multiple cells of the first type.
  • cell0 and cell1 of the multiple cells indicated by the first handover command are first-type cells, and when the first handover command is received, timer 0 is started for cell0 and timer 0 is started for cell1. Timer 1.
  • the timing duration of timer 0 and timer 1 may be the same or different.
  • Figure 6a uses the same timing duration of Timer 0 and Timer 1 as an example.
  • the terminal selects the target cell in the preferred set ⁇ cell0, cell1 ⁇ , after timer 0 and timer 1 expire, the terminal is in all candidate target cells including ⁇ cell0, cell1 ⁇ Select the target cell.
  • cell0 and cell1 of the multiple cells indicated by the first handover command are first-type cells, and when the first handover command is received, timer 0 is started for cell0 and cell1.
  • timer 0 is running, the terminal selects a target cell in the preferred set ⁇ cell0, cell1 ⁇ , and after timer 0 expires, the terminal selects a target cell from all candidate target cells including ⁇ cell0, cell1 ⁇ .
  • the terminal receives a second handover command from the network device, and the second handover command indicates one or more cells of the first type.
  • the terminal in response to receiving the second handover command, the terminal starts a timer for timing the second cell. For distinguishing description, it is recorded as the third timer here. Since the second timer has not expired, the third cell is added to the preferred range. Within the intersecting duration of the second timer and the third timer, the target cell is determined in the preferred range including the third cell.
  • the preferred protection of the first type cell indicated by the first handover command becomes invalid, and the target cell is selected from the first type cell indicated by the second handover command.
  • the second handover command indicating the third cell when the third cell satisfies the handover condition, the third cell is determined to be the target cell. After the third timer expires, the protection of the priority selection of the third cell becomes invalid.
  • the target cell can be selected from the range of all candidate target cells including the third cell, that is, in the first type of cell and the second type of cell Select the target cell in.
  • the third cell is the first-type cell indicated by the second handover command.
  • the third cell is any one of the multiple first-type cells indicated by the second handover command.
  • corresponding timers may be set for multiple first-type cells indicated by the second handover command, or the same timer may be set for multiple first-type cells.
  • the timer setting mechanism is similar to the above description of the second timer, and the above description can be referred to, which will not be repeated here.
  • a second switching command is received.
  • cell3 is the first type cell
  • timer 2 is started for cell3.
  • cell3 is added to the preferred set.
  • timer 0 and timer 1 are running, timer 0, timer 1 and timer 2 have an intersecting duration. Within the intersecting duration, the terminal is in ⁇ cell0 , Cell1, cell3 ⁇ select the target cell from the set.
  • the cell in the ⁇ cell0, cell1, cell3 ⁇ set that meets the handover condition first is determined as the target cell, or the channel in the cell that meets the handover condition in the ⁇ cell0, cell1, cell3 ⁇ set is determined The cell with the best condition is determined as the target cell.
  • timer 0 and timer 1 expire and timer 2 has not expired, after timer 0 and timer 1 expire, the preferred protection of cell0 and cell1 will become invalid.
  • timer 2 is running, the terminal is in ⁇ cell3 ⁇ Select the target cell. After timer 2 expires, the terminal selects a target cell from all candidate target cells including ⁇ cell3 ⁇ .
  • Fig. 7b on the basis of the example shown in Fig. 6b, when the timer 0 is running, the second switching command is received.
  • cell3 is the first type cell
  • timer 2 is started for cell3. After timer 2 is started, cell3 is added to the preferred set.
  • timer 0 and timer 2 have an intersecting duration. Within the intersecting duration, the terminal selects from the ⁇ cell0, cell1, cell3 ⁇ set Target cell.
  • the cell in the ⁇ cell0, cell1, cell3 ⁇ set that first meets the handover condition is determined as the target cell, or the channel in the cell that meets the handover condition in the ⁇ cell0, cell1, cell3 ⁇ set is determined
  • the cell with the best condition is determined as the target cell.
  • timer 0 expires and timer 2 has not expired, after timer 0 expires, the preferred protection of cell0 and cell1 becomes invalid, and the terminal selects the target cell in ⁇ cell3 ⁇ while timer 2 is running. After timer 2 expires, the terminal selects a target cell from all candidate target cells including ⁇ cell3 ⁇ .
  • the timer is started.
  • the second cell is not allowed to be the target cell. If there is a first type cell that meets the handover condition, the first type cell that meets the handover condition is determined as the target cell and the timer is stopped. After the timer expires, the second cell is determined as the target cell.
  • the timer in the third implementation manner is for the second cell. Recorded as the fourth timer.
  • the multiple candidate target cells indicated by the first handover command include a second cell, and the second cell is a second type cell.
  • the fourth timer is started. While the fourth timer is running, continue to measure and evaluate each candidate target cell. Once it is determined that a certain first type cell meets the handover condition, for example, the first cell meets the first handover condition, the first cell is determined as the target Cell and stop the fourth timer. If no cell of the first type meets the handover condition while the fourth timer is running, the second cell is determined as the target cell after the fourth timer expires. In one case, if the second cell no longer meets the second handover condition while the fourth timer is running, the fourth timer will be terminated.
  • the second cell is any cell in the second type of cell. It can be seen that the timer in the third implementation manner works on the second type of cell, and the function can be regarded as a delayed waiting function.
  • a timer is started to wait for timing, and when the timer is running, continue to Each candidate target cell is measured, and after the timer expires, if the first type of cell has not been selected to meet the handover condition, the second type of cell is taken as the target cell.
  • the fourth timer when the fourth timer is running, another cell of the second type may first meet the handover condition.
  • the fourth cell is the second type of cell.
  • the fourth cell may be indicated by the first handover command, or may be indicated by the second handover command received while the fourth timer is running.
  • the fifth timer is started.
  • the fifth timer is for timing the fourth cell.
  • the fourth cell is not allowed to be the target cell. If no cell is selected as the target cell after the fifth timer expires, the fourth cell is used as the target cell.
  • the second cell and the fourth cell are not allowed to be the target cells. If after the fourth timer expires, no cell of the first type meets the handover condition, the second cell is determined as the target cell, and the fifth timer is terminated. During the operation period of the fourth timer and the fifth timer, if a first type cell meets the handover condition, the first type cell is determined as the target cell, and the fourth timer and the fifth timer are terminated.
  • the terminal preferentially selects the first type of cell according to the selection rule, because the first type of cell supports the common service of the terminal with the source cell during the handover process. This can help implement the solution that the terminal maintains connections with the source cell and the target cell during the handover process.
  • the conditional switching scheme can be combined with the eMBB scheme to achieve high reliability and zero interruption during the switching process.
  • the terminal performs data transmission with the source cell.
  • S901 The terminal sends a measurement report to the source cell, and the source cell receives the measurement report from the terminal.
  • the measurement report is the measurement result of the terminal on multiple neighboring cells.
  • S902 The source cell makes an early handover decision.
  • the source cell sends an early handover request to multiple cells, and the multiple cells receive the early handover request from the source cell.
  • Figure 9 only shows that the target cell receives the early handover request, as an illustration.
  • S904 The multiple cells perform admission control after receiving the early handover request.
  • S905 Part or all of the multiple cells respectively return a handover confirmation message to the source cell, and the source cell receives the handover confirmation message from some or all of the multiple cells.
  • the cell that agrees to receive the terminal will return a handover confirmation message.
  • S906 The source cell sends a handover command to the terminal, and the terminal receives the handover command from the source cell.
  • the handover command indicates multiple candidate target cells. For example, all cells that agree to receive the terminal are set as candidate target cells.
  • switching commands there may be one or more switching commands, the definition and function of which are the first switching command and/or the second switching command described above.
  • the terminal evaluates the candidate target cell indicated by the handover command, and determines the target cell among multiple candidate target cells.
  • the specific method for determining the target cell is as described above.
  • S908 The terminal sends a random access preamble to the target cell, and the target cell receives the random access preamble from the terminal.
  • the target cell returns a random access response message to the terminal, and the terminal receives the random access response message from the target cell.
  • the target cell After detecting the preamble sent by the terminal, the target cell sends a random access response message to the terminal.
  • the terminal sends a handover complete message to the target cell, and the target cell receives the handover complete message from the terminal.
  • the handover complete message may be a reconfiguration complete message.
  • S911 The target cell sends a contention resolution message to the terminal.
  • the terminal in the random access process of S908 to S911, the terminal maintains an RRC connection with the source cell and transmits user data.
  • RACH random access channel
  • the terminal After receiving the handover complete message, the terminal completes the random access process, establishes an RRC connection with the target cell, and performs user data transmission with the target cell.
  • the conditional handover scheme enables the source cell to configure multiple candidate target cells for the terminal through early handover decisions, and the terminal performs measurement and evaluation on multiple candidate target cells, and the terminal autonomously determines the time point for cell handover to avoid sending handover commands too early Or too late to cause handover failure, which improves the reliability of the handover process.
  • the terminal can select the first-type cell as the target cell, which can help to combine conditional handover with the eMBB solution. On the basis of improving the reliability in the switching process, the data transmission interruption time during the switching process is reduced.
  • the terminal performs random access to the target cell after determining the target cell. Random access to the target cell may fail. For example, in the conditional switching and eMBB scheme described in the foregoing method embodiment, during the random access process of S908 to S911, if the terminal does not receive the random access response message or the contention resolution message, random access will occur. Entry failed. For RACH-less handover, the terminal sends an RRC reconfiguration message in the pre-configured resource. If the contention resolution message cannot be received after the maximum time period is exceeded, it is determined that the random access fails.
  • the following describes the solution of this application for the terminal's random access failure to the target cell.
  • This method can be combined with the above method for determining the target cell, or a solution can be formed separately as the solution that needs to be protected in the embodiment of this application .
  • the source cell sends one or more RRC messages to the terminal, and the terminal receives one or more RRC messages from the source cell.
  • the RRC message is used as a handover command for illustration.
  • One or more handover commands indicate multiple candidate target cells.
  • the terminal selects cell 1 as a target cell from a plurality of candidate target cells.
  • the method for the terminal to determine cell 1 as the target cell may follow the method provided in the foregoing method embodiment, or may follow other selection methods.
  • S1001 may be an optional step.
  • the handover command in S1001 may only indicate one candidate target cell.
  • the terminal in S1002 may determine the time to initiate random access to this candidate target cell.
  • the terminal initiates a random access procedure to cell 1.
  • the terminal in the process of initiating random access to cell 1, the terminal maintains the RRC connection with the source cell and maintains data transmission.
  • the terminal selects cell 2 as the target cell from multiple candidate target cells.
  • the terminal may continue to maintain the connection with the source cell and perform data transmission through the source cell.
  • Fig. 10 takes the terminal selecting cell 2 as the target cell as an example. If cell 2 is selected as the target cell, S1005 is executed.
  • S1005 The terminal initiates a random access procedure to cell 2.
  • the terminal maintains the RRC connection with the source cell.
  • the terminal when random access to cell 1 fails, the terminal can delete cell 1 from multiple candidate target cells, and then select cell 2 from the candidate target cells of deleted cell 1; also It is possible to reserve cell 1 in multiple candidate target cells, and continue to select cell 2 among the multiple candidate target cells.
  • the selected cell 2 may be cell 1 or other cells.
  • the terminal sends a first indication message to the source cell when random access to cell 1 fails.
  • the first indication message is used to indicate that the random access to cell 1 fails, and the first indication message may carry the identity and/or frequency information of cell 1.
  • the source cell After receiving the random access failure indication message, the source cell sends a second indication message to the terminal, where the second indication message is used to instruct the terminal to delete cell 1 from the candidate target cell. Or, after receiving the random access failure indication message, the source cell does not send the second indication message to the terminal.
  • the terminal does not receive the second indication message, it reserves cell 1 in the candidate target cells, and continues to measure the multiple candidate target cells to select cell 2.
  • the first indication message is used to indicate that random access to cell 1 fails, and/or is used to indicate that cell 1 is deleted from the candidate target cell.
  • the first indication message may carry the identity and/or frequency information of cell 1.
  • the message used to indicate the random access failure to cell 1 and the message used to indicate to delete cell 1 from the candidate target cell may also be two different indication messages.
  • the terminal can avoid random access to cell 1 again.
  • the terminal can avoid random access to cell 1 again.
  • the indication of the first indication message and/or the second indication message it is possible to achieve consistency between the terminal and the candidate target cells on both sides of the source cell.
  • the terminal can continue to measure multiple candidate target cells including cell 1.
  • the terminal can set the layer 3 (L3) filter of cell 1, and then continue to measure cell 1. For example, restart the L3 filter of cell 1, or update the filter coefficient of the L3 filter of cell 1, or restart the L3 filter of cell 1 and update the filter coefficient.
  • L3 layer 3
  • the measurement model for the terminal to measure the cell is shown in Figure 11. After the measured value is obtained by the physical layer (layer1, L1), it is reported to the higher layer after passing through the L1 filter. After the upper layer is filtered by the L3 filter, the output filter result is sent to the evaluation module for evaluation, and the evaluation result is obtained.
  • the L1 filter is implemented on the terminal side and does not constitute a limitation to this patent.
  • the L3 filter has been standardized.
  • the L3 filter obtains the filtering result according to the following filtering formula (1) during filtering.
  • M n is the latest output measurement result of the L1 filter
  • Fn is the updated output result of the L3 filter, which is also used as the input of the evaluation module
  • F n-1 is the historical L3 filter output
  • F 0 is set to M 1 . It can be obtained from the formula that F 1 is equal to M 1 , that is, the first result output by the L1 filter is the output of the L3 filter.
  • k is the L3 filter coefficient, and different measurement quantities can have different k values.
  • the updated L3 filter coefficients can be at the terminal level, or they can be used individually by each candidate target cell, and can be indicated to the terminal by the source cell, or specified in the agreement. For example, the source cell can configure the updated L3 filter coefficient in the conditional handover command, or configure the updated L3 filter coefficient in other measurement configuration messages.
  • the connection with the source cell is maintained to ensure the normal transmission of user data, the candidate target cell is continuously evaluated, and the next target cell is selected for random access to ensure cell handover Work properly.
  • the source cell may have radio link failure (radio link failure, RLF)
  • RLF radio link failure
  • the terminal needs to send an RLF indication message to the target cell.
  • the target cell may also send a confirmation message to the source cell, which is used to instruct to cancel the common service of the terminal during the handover process.
  • the selection rule may also include that, in a scenario where RLF occurs in the source cell, compared to the first type cell, the second type cell is preferentially selected as the target cell. In this way, when RLF occurs in the source cell, the terminal selects the second type of cell as the target cell, and in the process of random access to the second type of cell, it only needs to disconnect the RRC connection with the source cell.
  • an embodiment of the present application further provides a cell handover apparatus 1200, which is configured to perform operations performed by the terminal in the foregoing method embodiment.
  • the cell handover device 1200 includes a processing unit 1201 and a communication unit 1202.
  • the communication unit 1202 is configured to receive one or more radio resource control RRC messages from the source cell.
  • the one or more RRC messages are used to indicate multiple candidate target cells, the multiple candidate target cells include a first type cell and a second type cell, and the definitions of the first type cell and the second type cell Refer to above.
  • the processing unit 1201 is configured to determine the target cell according to the selection rule.
  • processing unit 1201 and the communication unit 1202 in the device 1200 for cell handover can also implement other operations or functions performed by the terminal in the foregoing method embodiment, and the repetition will not be repeated.
  • an embodiment of the present application further provides a cell handover device 1300, which is used to implement operations performed by the terminal in the foregoing method embodiment.
  • the cell handover device 1300 includes: a transceiver 1301, a processor 1302, and a memory 1303.
  • the memory 1303 is optional.
  • the transceiver 1301 is used to transmit messages or signaling with other communication devices, for example, to receive RRC messages from a source cell.
  • the processor 1302 is coupled with the memory 1303, and is configured to call a program in the memory 1303, and when the program is executed, the processor 1302 is caused to perform operations performed by the terminal in the foregoing method embodiment.
  • the memory 1303 is used to store programs executed by the processor 1302.
  • the functional module processing unit 1201 in FIG. 12 may be implemented by the processor 1302, and the communication unit 1202 may be implemented by the transceiver 1301.
  • the processor 1302 performs the following operations: used to determine the target cell according to the selection rule.
  • the processor 1302 may also perform other operations or functions performed by the terminal in the foregoing method embodiments, and the repetitions will not be repeated.
  • the processor 1302 may be a central processing unit (CPU), a network processor (NP) or a combination of a CPU and an NP.
  • CPU central processing unit
  • NP network processor
  • the processor 1302 may further include a hardware chip.
  • the aforementioned hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD) or a combination thereof.
  • ASIC application-specific integrated circuit
  • PLD programmable logic device
  • the above-mentioned PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.
  • CPLD complex programmable logic device
  • FPGA field-programmable gate array
  • GAL generic array logic
  • the memory 1303 may include a volatile memory (volatile memory), such as random-access memory (RAM); the memory 1303 may also include a non-volatile memory (non-volatile memory), such as flash memory (flash memory). memory), hard disk drive (HDD) or solid-state drive (SSD); the memory 1303 may also include a combination of the foregoing types of memory.
  • volatile memory volatile memory
  • non-volatile memory non-volatile memory
  • flash memory flash memory
  • HDD hard disk drive
  • SSD solid-state drive
  • the memory 1303 may also include a combination of the foregoing types of memory.
  • an embodiment of the present application further provides a chip, including a processor, for supporting the cell handover device to implement the terminal involved in the above method embodiment Features.
  • the chip is connected to a memory or the chip includes a memory, and the memory is used to store the necessary program instructions and data of the cell handover device.
  • the embodiment of the present application provides a computer storage medium that stores a computer program, and the computer program includes instructions for executing the foregoing method embodiments.
  • the embodiments of the present application provide a computer program product containing instructions, which when run on a computer, cause the computer to execute the foregoing method embodiments.
  • this application can be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.
  • computer-usable storage media including but not limited to disk storage, CD-ROM, optical storage, etc.
  • These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device.
  • the device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.
  • These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment.
  • the instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

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Abstract

一种小区切换的方法及装置，用以解决如何在多个候选目标小区中选择合适的目标小区的问题。该方法包括：从源小区接收一个或多个无线资源控制RRC消息，所述一个或多个RRC消息用于指示多个候选目标小区，所述多个候选目标小区包括第一类小区和第二类小区，所述第一类小区支持与所述源小区在切换过程中共同服务于终端，所述第二类小区不支持与所述源小区在切换过程中共同服务于所述终端，所述第一类小区包括第一小区，所述第二类小区包括第二小区；按照选择规则，确定目标小区，其中，所述选择规则包括：相较于所述第二类小区，优先选择所述第一类小区作为目标小区。

Description

一种小区切换的方法及装置 技术领域
本申请涉及通信技术领域，特别涉及一种小区切换的方法及装置。
背景技术
在无线通信系统中，当终端移动时，根据信号强度的变化或者网络侧的负载均衡的需求，可能会发生服务小区的切换。为提高切换过程的可靠性，现有技术中提出了一种条件切换技术。源基站向终端发送切换命令，在切换命令中指示多个候选目标小区以及该多个候选目标小区各自的切换条件。终端接收到源基站发送的切换命令后，不会立即执行切换过程，而是继续保持与源基站的无线资源控制(radio resource control，RRC)连接，并对该多个候选目标小区进行测量以及切换条件的评估。若该多个候选目标小区中的一个候选目标小区满足对应的切换条件，则该候选目标小区即为终端的目标小区。终端执行由源小区到该目标小区的切换过程。在切换过程中，终端会断开与源基站的RRC连接，并针对目标小区执行随机接入过程。终端在向目标小区发送切换完成消息后，终端建立与目标小区的RRC连接。
上述条件切换技术的实现方式，在切换过程中终端会与源基站断开连接，直到切换完成与目标小区建立连接，这个过程中终端的数据传输是中断的。为降低切换过程中的数据传输中断时间，现有技术提出了一种解决方案。基于上述条件切换技术，终端在执行切换过程中继续维持与源基站的RRC连接，并继续与源基站进行数据传输，直到终端建立与目标小区的RRC连接，这样在切换过程中可能会存在终端同时与源基站和目标小区保持连接的情况。
虽然这种解决方案能够达到切换过程零中断的效果，但是如何在多个候选目标小区中选择目标小区是需要解决的问题。
发明内容
本申请提供一种小区切换的方法及装置，用以解决如何在多个候选目标小区中选择合适的目标小区的问题。
第一方面，提供一种小区切换的方法，该方法的执行主体可以是终端，该方法可以通过以下步骤实现：源小区向终端指示多个候选目标小区，终端根据应用场景，优先选择第一类小区作为目标小区，或者优先选择第二类小区作为目标小区。例如，若终端优先选择第一类小区作为目标小区，则有助于在切换过程中终端与源小区和目标小区均保持连接这一方案的实现。又例如，当源小区发生RLF时，终端优先选择第二类小区作为目标小区，避免选择第一类小区作为目标小区时需要发送指示信令造成资源浪费。
在一个可能的设计中，从源小区接收一个或多个无线资源控制RRC消息，所述一个或多个RRC消息用于指示多个候选目标小区，所述多个候选目标小区包括第一类小区和第二类小区，所述第一类小区支持与所述源小区在切换过程中共同服务于终端，所述第二类小区不支持与所述源小区在切换过程中共同服务于所述终端，所述第一类小区包括第一小区，所述第二类小区包括第二小区；在第一应用场景下，按照选择规则，确定目 标小区，其中，所述选择规则包括：相较于所述第二类小区，优先选择所述第一类小区作为目标小区。通过源小区提前配置的多个候选目标小区，终端能够对多个候选目标小区进行测量评估，终端自主决定小区切换的时间点，避免切换命令发送过早或过晚导致切换失败的问题，提高了切换过程中的可靠性。通过选择准则，终端优选第一类小区作为目标小区，能够有助于将条件切换与eMBB方案进行结合。在提高切换过程中的可靠性的基础上，减少切换过程中数据传输中断时间。
在一个可能的设计中，RRC消息包括RRC连接重配置消息、条件切换命令、切换命令或候选目标小区配置消息。
在一个可能的设计中，通过定时器来实现优选第一类小区作为目标小区的方案。定时器的相关配置可以通过上述RRC消息进行配置。其中，定时器的相关配置如对定时时长和延迟时长等参数的配置。延迟时长是指在切换条件满足后延迟一段时间再启动定时器。当然，定时器的相关配置还可以通过其他消息来指示，也可以采用默认配置。例如通过协议规定。
在一个可能的设计中，启动第一定时器；在所述第一定时器运行时，在所述第一类小区中确定所述目标小区；在所述第一定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。通过第一定时器，能够在第一定时器运行时实现优选第一类小区作为目标小区。
在一个可能的设计中，在所述第一定时器运行时，若所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区。
在一个可能的设计中，在所述第一定时器超时后，若所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区，否则，若所述第二小区满足第二切换条件，则确定所述第二小区为所述目标小区。
在一个可能的设计中，在所述第一定时器超时后，若所述第二小区满足第二切换条件且所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区。
在一个可能的设计中，从源小区接收多个RRC消息，所述多个RRC消息用于指示所述多个候选目标小区，所述多个RRC消息包括第一RRC消息和第二RRC消息，所述第一RRC消息指示所述第一小区，所述第二RRC消息指示第三小区，所述第三小区属于所述第一类小区；响应于接收到所述第一RRC消息，启动所述第一定时器；在所述第一定时器运行时，从所述网络设备接收所述第二RRC消息；响应于接收到所述第二RRC消息，重启所述第一定时器。通过每接收到一个包含第一类小区的RRC消息，便启动或重启第一定时器，将第一定时器作用于终端的所有候选目标小区。
在一个可能的设计中，从源小区接收多个RRC消息，所述多个RRC消息用于指示所述多个候选目标小区，所述多个RRC消息包括第一RRC消息，所述第一RRC消息指示所述第一小区；响应于接收到所述第一RRC消息，启动第二定时器；在所述第二定时器运行时，在所述第一小区中确定所述目标小区，在所述第二定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。这样能够针对每一个第一类小区启动对应的定时器，将定时器作用与该第一类小区。
在一个可能的设计中，所述多个RRC消息还包括第二RRC消息，所述第二RRC消息指示第三小区，所述第三小区为所述第一类小区；在所述第二定时器运行时，从所述网络设备接收所述第二RRC消息；响应于接收到所述第二RRC消息，启动第三定时器；在 所述第二定时器和所述第三定时器的相交时长内，在所述第一小区和所述第三小区中确定所述目标小区；在所述第二定时器超时后且所述第三定时器运行时，在所述第三小区中确定所述目标小区；在所述第三定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。本设计考虑到了小区级别的定时器出现相交的场景。
在一个可能的设计中，响应于确定所述第二小区满足第二切换条件，启动第四定时器；在所述第四定时器运行时，在所述第一类小区中确定所述目标小区，在所述第四定时器超时后，确定所述第二小区为所述目标小区，其中，所述第二小区满足所述第二切换条件。本设计中的定时器针对第二类小区起作用，起到了延迟等待的作用，一旦有第二类小区先于第一类小区满足切换条件，则启动定时器进行等待计时，在该定时器运行时，继续对各个候选目标小区进行测量，在该定时器超时后，若还未选择出第一类小区满足切换条件，则将该第二类小区作为目标小区。
在一个可能的设计中，在所述第四定时器运行时，若确定所述第二小区不满足所述第二切换条件，则终止所述第四定时器。本设计提出了第四定时器终止的条件。
在一个可能的设计中，响应于确定所述目标小区，终止定时器，所述定时器包括第一定时器、第二定时器、第三定时器或第四定时器中的任一种。本设计提出了上述举例的各种定时器的终止条件。在上述举例的各种定时器运行期间，一旦确定了目标小区，便将定时器终止。
在一个可能的设计中，所述第一类小区和所述第二类小区还可以具有下述任意一种或多种特征：所述第一类小区所属基站与所述源小区所属基站具有直接的通信接口，所述第二类小区所属基站与所述源小区所属基站不具有直接的通信接口；所述第一类小区所属基站与所述源小区所属基站的协议版本相同，所述第二类小区所属基站与所述源小区所属基站的协议版本不同；所述第一类小区支持增强的连接维持eMBB技术，所述第二类小区不支持所述eMBB技术；所述第一类小区与所述源小区的频率不一致，所述第二类小区与所述源小区的频率一致。
在一个可能的设计中，从源小区接收一个或多个无线资源控制RRC消息，所述一个或多个RRC消息用于指示多个候选目标小区，所述多个候选目标小区包括第一类小区和第二类小区，所述第一类小区支持与所述源小区在切换过程中共同服务于终端，所述第二类小区不支持与所述源小区在切换过程中共同服务于所述终端，所述第一类小区包括第一小区，所述第二类小区包括第二小区；在第一应用场景下，按照选择规则，确定目标小区，其中，所述选择规则还包括：在所述源小区发生无线链路失败的场景下，相较于所述第一类小区，优先选择所述第二类小区作为目标小区。
在一个可能的设计中，保持与所述源小区的RRC连接，并执行向所述目标小区的随机接入的过程。有助于将条件切换技术与eMBB方案结合，实现切换过程中的高可靠性和零中断的效果。
在一个可能的设计中，若所述随机接入失败，则：向所述源小区发送第一指示消息，从所述源小区接收第二指示消息，所述第一指示消息用于指示所述随机接入失败，所述第二指示消息用于指示将所述目标小区从所述多个候选目标小区中删除；或，将所述目标小区从所述多个候选目标小区中删除。通过将目标小区删除，能够避免终端再次对该目标小区进行随机接入。通过第一指示消息和/或第二指示消息的指示，能够实现终端与源小区两侧的候选目标小区一致。若所述随机接入失败，还可以保留该目标小区，并：重启所述目 标小区的层三滤波器；或，更新所述目标小区的层三滤波器的滤波系数，并重启所述层三滤波器；或，更新所述目标小区的层三滤波器的滤波系数。通过层三滤波器的设置，能够获取该目标小区的最新的测量结果，降低该目标小区的历史测量结果的权重。综上，在向目标小区随机接入失败时，通过保持与源小区的连接，保证用户数据正常传输，并继续对候选目标小区进行评估，以及选择下一个目标小区进行随机接入，保证小区切换正常进行。
第二方面，提供一种小区切换的方法，该方法的执行主体可以是终端，该方法具体通过以下步骤实现：从一个或多个候选目标小区中确定目标小区；保持与源小区的无线资源控制RRC连接，执行向所述目标小区的随机接入的过程；若所述随机接入失败，则：将所述目标小区从所述一个或多个候选目标小区中删除；或，重启所述目标小区的层三滤波器；或，更新所述目标小区的层三滤波器的滤波系数，并重启所述层三滤波器；或，更新所述目标小区的层三滤波器的滤波系数。在向目标小区随机接入失败时，通过保持与源小区的连接，保证用户数据正常传输，并继续对候选目标小区进行评估，以及选择下一个目标小区进行随机接入，保证小区切换正常进行。
在一个可能的设计中，向所述源小区发送第一指示消息，从所述源小区接收第二指示消息，所述第一指示消息用于指示所述随机接入失败，所述第二指示消息用于指示将所述目标小区从所述一个或多个候选目标小区中删除；根据所述第二指示消息，将所述目标小区从所述一个或多个候选目标小区中删除。通过将目标小区删除，能够避免终端再次对该目标小区进行随机接入。通过第一指示消息和/或第二指示消息的指示，能够实现终端与源小区两侧的候选目标小区一致。
在一个可能的设计中，从所述源小区接收第一RRC消息，所述第一RRC消息用于指示所述一个或多个候选目标小区。
在一个可能的设计中，所述多个候选目标小区包括第一类小区，或，所述多个候选目标小区包括所述第一类小区和第二类小区，所述第一类小区支持与所述源小区在切换过程中共同服务于终端，所述第二类小区不支持与所述源小区在切换过程中共同服务于所述终端，所述第一类小区包括第一小区，所述第二类小区包括第二小区。
在一个可能的设计中，按照选择规则，确定目标小区，其中，所述选择规则包括：相较于所述第二类小区，优先选择所述第一类小区作为目标小区。
第三方面，提供一种小区切换的装置，该装置具有实现上述第一方面、第二方面、第一方面的任一种可能的设计或第二方面的任一种可能的设计的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
在一个可能的设计中，该装置可以是芯片或者集成电路。
在一个可能的设计中，该装置包括收发器和处理器，收发器用于与其他通信设备进行通信，处理器用于与存储器进行耦合，执行存储器存储的程序，当程序被执行时，所述装置可以执行上述第一方面、第二方面、第一方面的任一种可能的设计或第二方面的任一种可能的设计中所述的方法。
在一个可能的设计中，该装置还包括存储器，用于存储处理器执行的程序。
在一个可能的设计中，该装置为终端。
第四方面，提供一种芯片，该芯片与存储器相连或者该芯片包括存储器，用于读取并执行所述存储器中存储的软件程序，以实现如上述第一方面、第二方面、第一方面的 任一种可能的设计或第二方面的任一种可能的设计中所述的方法。
第五方面，提供了一种通信系统，该通信系统包括第三方面所述的装置。
第六方面，提供一种计算机存储介质，存储有计算机程序，该计算机程序包括用于执行上述各方面和各方面的任一可能的设计中方法的指令。
第七方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述各方面和各方面的任一可能的设计中所述的方法。
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图1为本申请实施例中通信系统架构示意图；
图2为本申请实施例中小区切换的方法流程示意图；
图3为本申请实施例中优选第一类小区的实现方式一的示意图之一；
图4为本申请实施例中优选第一类小区的实现方式一的示意图之二；
图5为本申请实施例中优选第一类小区的实现方式二的示意图之一；
图6a为本申请实施例中优选第一类小区的实现方式二的示意图之二；
图6b为本申请实施例中优选第一类小区的实现方式二的示意图之三；
图7a为本申请实施例中优选第一类小区的实现方式二的示意图之四；
图7b为本申请实施例中优选第一类小区的实现方式二的示意图之五；
图8a为本申请实施例中优选第一类小区的实现方式三的示意图之一；
图8b为本申请实施例中优选第一类小区的实现方式三的示意图之二；
图9为本申请实施例中条件切换与eMBB方案结合实现小区切换的方法示意图；
图10为本申请实施例中向目标小区随机接入失败的解决方法示意图；
图11为本申请实施例中终端对小区进行测量的测量模型示意图；
图12为本申请实施例中小区切换的装置结构示意图之一；
图13为本申请实施例中小区切换的装置结构示意图之二。
具体实施方式
本申请实施例提供一种小区切换的方法及装置，有助于解决如何在多个候选目标小区中选择合适的目标小区的问题。其中，方法和装置是基于同一构思的，由于方法及装置解决问题的原理相似，因此装置与方法的实施可以相互参见，重复之处不再赘述。本申请实施例的描述中，“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。字符“/”一般表示前后关联对象是一种“或”的关系。本申请中所涉及的至少一个是指一个或多个；涉及的多个，是指两个或两个以上。另外，需要理解的是，在本申请的描述中，“第一”、“第二”等词汇，仅用于区分描述的目的，而不能理解为指示或暗示相对重要性，也不能理解为指示或暗示顺序。
图1示出了本申请实施例提供的小区切换的方法适用的一种可能的通信系统的架构，参阅图1所示，通信系统100中包括：该通信系统100包括：网络设备101和终端102。
网络设备101为具有无线收发功能的设备或可设置于该设备的芯片，该设备包括但不限于：演进型节点B(evolved Node B，eNB)、无线网络控制器(radio network controller， RNC)、节点B(Node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved NodeB，或home Node B，HNB)、基带单元(baseband unit，BBU)，无线保真(wireless fidelity，WIFI)系统中的接入点(access point，AP)、无线中继节点、无线回传节点、传输点(transmission and reception point，TRP或者transmission point，TP)等，还可以为5G(如NR)系统中的gNB，或，传输点(TRP或TP)，5G系统中的基站的一个或一组(包括多个天线面板)天线面板，或者，还可以为构成gNB或传输点的网络节点，如基带单元(BBU)，或，分布式单元(distributed unit，DU)等。
在一些部署中，gNB可以包括集中式单元(centralized unit，CU)和DU。gNB还可以包括射频单元(radio unit，RU)。CU实现gNB的部分功能，DU实现gNB的部分功能，比如，CU实现无线资源控制(radio resource control，RRC)，分组数据汇聚层协议(packet data convergence protocol，PDCP)层的功能，DU实现无线链路控制(radio link control，RLC)、媒体接入控制(media access control，MAC)和物理(physical，PHY)层的功能。由于RRC层的信息最终会变成PHY层的信息(即通过PHY层发送)，或者，由PHY层的信息转变而来，因而，在这种架构下，高层信令，如RRC层信令或PDCP层信令，也可以认为是由DU发送的，或者，由DU+RU发送的。可以理解的是，网络设备可以为CU节点、或DU节点、或包括CU节点和DU节点的设备。此外，CU可以划分为接入网RAN中的网络设备，也可以将CU划分为核心网CN中的网络设备，在此不做限制。
终端也可以称为用户设备(user equipment，UE)、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端设备、无线通信设备、用户代理或用户装置。本申请的实施例中的终端可以是手机(mobile phone)、平板电脑(Pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等等。本申请的实施例对应用场景不做限定。本申请中将具有无线收发功能的终端及可设置于前述终端的芯片统称为终端。
本申请实施例提供的小区切换的方法可以应用于各种通信系统，例如：长期演进(long term evolution，LTE)系统，全球互联微波接入(worldwide interoperability for microwave access，WiMAX)通信系统，第五代(5th Generation，5G)系统，如新一代无线接入技术(new radio access technology，NR)，及未来的通信系统，如6G系统等。本申请涉及终端在源基站到目标基站的切换，其中源基站和目标基站可以属于同一种通信系统，也可以属于不同的通信系统。例如，源基站和目标基站为LTE基站，或者，源基站和目标基站为NR基站，或者，源基站为LTE基站、目标基站为NR基站，或者，源基站为NR基站、目标基站为LTE基站。
需要说明的是，本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
下面将结合附图，对本申请实施例进行详细描述。
本申请涉及小区切换的相关过程，在以下描述中，终端从源小区切换到目标小区，源小区所属的网络设备与终端进行信息交互或数据交互，源小区所属的网络设备可以称为源基站，目标小区所属的网络设备可以称为目标基站。终端与源小区进行的信息/数据交互可以理解为终端与源基站进行的信息/数据交互。终端与目标小区进行的信息/数据交互可以理解为终端与目标基站进行的信息/数据交互。终端从源小区切换到目标小区可以理解为终端从与源基站连接切换到与目标基站连接。所述连接可以是指无线资源控制(radio resource control，RRC)连接。终端与小区或基站保持RRC连接，就可以与小区或基站进行信息交互或数据交互。
本申请的终端还可以具有能力使得终端在切换过程与源小区和目标小区均保持连接，直到终端与目标小区完成随机接入过程后再断开与源小区的连接，或通过其他触发方式终端断开与源小区的连接。这种方案可以称为增强的连接维持(enhanced make before break，eMBB)方案，或者称为同时连接切换方案，当然还可以称为其它名称。也可以称为，切换过程中源小区和目标小区共同服务于终端。这种方案能够实现终端在小区切换过程中数据传输不中断的效果。
进一步的，若要实现eMBB方案，即实现终端在切换过程与源小区和目标小区均保持连接，需要对源小区和目标小区的能力匹配也有要求。例如，要求源小区所属的源基站以及目标小区所属的目标基站满足以下至少一个条件：源基站与目标基站具有直接的通信接口；源基站与目标基站的协议版本相同；源小区和目标小区的频率不一致。其中，要求源小区和目标小区的频率不一致，是因为考虑到终端的能力不同，有些终端不能支持同频的两个小区的同时数据收发，故要求源小区和目标小区的频率不一致才能实现eMBB方案。以上只是举例，并不构成限制。
基于此，本申请可将候选目标小区规划为两种类型，用第一类小区和第二类小区来表示。其中，第一类小区支持与源小区在切换过程中共同服务于终端，第二类小区不支持与源小区在切换过程中共同服务于该终端。该终端是指发生小区切换的终端。或者说，第一类小区所属的基站与源小区所属的源基站具有直接的通信接口，第二类小区所属的基站与源小区所属的源基站不具有直接的通信接口。或者说，第一类小区所属的基站与源小区所属的源基站的协议版本相同，第二类小区所属的基站与源小区所属的源基站的协议版本不同。或者说，第一类小区支持eMBB方案，第二类小区不支持eMBB方案。或者说，所述第一类小区与所述源小区的频率不一致，所述第二类小区与所述源小区的频率一致，针对终端不能支持同频的两个小区的同时数据收发的场景。
本申请实施例的基本思想是，源小区向终端指示多个候选目标小区，终端根据应用场景，优先选择第一类小区作为目标小区，或者优先选择第二类小区作为目标小区。例如，若终端优先选择第一类小区作为目标小区，则有助于在切换过程中终端与源小区和目标小区均保持连接这一方案的实现。
如图2所示，本申请提供的小区切换的方法的流程如下所述。
S201、源小区向终端发送一个或多个RRC消息，终端从源小区接收该一个或多个RRC消息。
其中，RRC消息可以包括RRC连接重配置消息、条件切换命令、切换命令或候选目标小区配置消息等。以下RRC消息用切换命令为例进行描述。
源小区向终端发送的一个或多个切换命令用于指示多个候选目标小区。该多个候选 目标小区中包括第一类小区和第二类小区。其中，该第一类小区和第二类小区的解释如上文所述。
实际应用中，源小区可能会间隔性地向终端发送多个切换命令。例如，源小区向终端发送第一切换命令之后，经过一段时长后向终端发送第二切换命令。任意一个切换命令中指示的候选目标小区可能为其中一类或两类小区。具体地说，任意一个切换命令中指示的候选目标小区可能均为第一类小区，也可能均为第二类小区，也可能既包括第一类小区又包括第二类小区。
源小区也可能向终端发送一个切换命令，该一个切换命令指示的多个候选目标小区中既包括第一类小区又包括第二类小区。
在一个可能的实现方式中，在切换命令中用小区的标识信息来指示多个候选目标小区，其中，小区的标识信息可以为现有技术中任意可以用来标识小区的信息，如小区标识(identity，ID)。在切换命令中还可以指示每一个候选目标小区的切换条件，以及指示每一个候选目标小区的类别。
其中，候选目标小区的类别即第一类或第二类。切换命令可以指示第一类或第二类的索引，或者指示第一类小区或第二类小区的含义，例如是否支持与源小区在切换过程中共同服务于终端。候选目标小区的切换条件可以与测量上报条件相同，例如采用测量事件触发切换。本申请中，当终端收到切换命令后，会对切换命令中指示的候选目标小区进行切换评估，判断是否需要触发切换。例如，终端判断候选目标小区是否满足切换条件的方式为，终端在满足测量事件进入条件，并持续一段时间后，即确定满足切换条件。其中，测量事件可以为以下任意一种：1)候选目标小区的信号质量优于源小区的信号质量一个偏移值，例如，A3事件：候选目标小区＞源小区+3db；2)源小区的信号质量低于门限1，和/或，候选目标小区的信号质量大于门限2。以上描述是示例性的，切换触发条件也可以采用其他方式。
每一个候选目标小区的切换条件可能相同或不同，若不同可能是指测量事件不同，例如A3和A4事件。也可能是相同测量事件，但是门限值或偏移值不同。
源小区提前为终端通过切换命令配置多个候选目标小区，能够在源小区与终端的通信质量较好时完成候选目标小区的配置。终端可以从多个候选目标小区中选择合适的目标小区进行切换，终端还可以选择合适的切换时机，这样能够提高切换的可靠性。
S202、终端按照选择规则，确定目标小区。
本申请中终端在多个候选目标小区中选择目标小区可以按照选择规则进行选择，如，选择规则可以包括：相较于第二类小区，优先选择第一类小区作为目标小区。
如上所述，终端在接收到切换命令后，会对切换命令中指示的候选目标小区进行评估，当候选目标小区的测量结果满足对应的切换条件时，才有机会被选择为目标小区。按照选择规则，第一类小区的优先级要高于第二类小区的优先级，即优先选择第一类小区作为目标小区。
本申请中可以通过以下几种方式来实现优选第一类小区作为目标小区。可以理解实际应用中可以通过其他方式来实现优选第一类小区作为目标小区，本申请对实现方式给出举例说明。
为方便描述，假设多个候选目标小区中包括第一小区和第二小区，其中第一小区为第一类小区，第二小区为第二类小区。第一小区对应的切换条件为第一切换条件，第二 小区对应的切换条件为第二切换条件。可以理解，第一小区为多个候选目标小区中类别为第一类小区的任意一个小区，第二小区为多个候选目标小区中类别为第二类小区的任意一个小区。
在实现优选第一类小区作为目标小区的方法中，可以采用定时器来实现。根据以下对定时器的不同应用场景的设计，以下通过第一定时器、第二定时器、第三定时器……等来区分描述。以下描述中的任意定时器的相关配置都可以通过切换命令指示，也可以通过其他RRC消息进行配置。其中，定时器的相关配置如对定时时长和延迟时长等参数的配置。延迟时长是指在切换条件满足后延迟一段时间再启动定时器。当然，定时器的相关配置还可以通过其他消息来指示，也可以采用默认配置。例如通过协议规定。
实现方式一：
如图3所示，在定时器运行时，仅允许选择第一类小区作为目标小区，不允许在第二类小区中选择目标小区，在定时器超时后，才允许在第二类小区中选择目标小区。
这里的定时器可以记为第一定时器。即启动第一定时器，在第一定时器运行时，在第一类小区中确定目标小区，在第一定时器超时后，在第一类小区和第二类小区中确定目标小区。终端对切换命令指示的多个候选目标小区进行测量，在第一定时器运行时，若确定多个候选目标小区中的第一小区满足第一切换条件，则确定该第一小区为目标小区，同时停止第一定时器。可选的，这里确定为目标小区的第一小区，可以是在第一定时器运行时最先满足切换条件的第一类小区，也可以是在第一定时器运行时满足切换条件的第一类小区中信道条件最好的小区。
在第一定时器超时后，第二类小区可以作为目标小区的选择范围。终端可以在多个候选目标小区中的任意类别的小区中选择目标小区。可选的，在第一定时器超时后最先满足切换条件的小区作为目标小区，也可以在第一定时器超时后将满足切换条件的小区中信道条件最好的小区作为目标小区。
例如，若类别为第一类小区的小区先满足切换条件，则将类别为第一类小区的该小区确定为目标小区；若类别为第二类小区的小区先满足切换条件，则将类别为第二类小区的该小区确定为目标小区。按照上述假设，即在第一定时器超时后，若第一小区满足第一切换条件，则确定第一小区为目标小区，否则，若第二小区满足第二切换条件，则确定第二小区为目标小区。
还有一种可能，在第一定时器超时后，在确定目标小区时获得了第一小区的测量结果和第二小区的测量结果，且第一小区满足了第一切换条件，第二小区也满足了第二切换条件。这种情况下，还是按照第一类小区优选的规则，将第一小区确定为目标小区。
关于第一定时器的启动时机：
1)若终端从源小区接收了一个切换命令，根据这一个切换命令确定候选目标小区，则终端响应于接收到该切换命令，便启动第一定时器。
2)若终端从源小区接收多个切换命令，并根据该多个切换命令确定候选目标小区，则可能会出现在第一定时器运行期间接收到切换命令的场景。基于此，假设多个切换命令中包括第一切换命令和第二切换命令，第一切换命令在第二切换命令之前，且第一切换命令和第二切换命令指示的小区均包括第一类小区，则本申请中，响应于接收到第一切换命令，启动第一定时器；在第一定时器运行时，从网络设备接收到第二切换命令，响应于接收到第二切换命令，重启该第一定时器。当然，若在第一定时器超时后从网络 设备接收到第二切换命令，依旧重启该第一定时器。第一定时器运行时后对目标小区的选择规则如上所述。
对于第2)种启动时机的一种应用场景，举例来说，如图4所示，在接收到第一切换命令时启动该第一定时器，假设第一切换命令指示的多个小区中的cell0和cell1为第一类小区，则终端在优选集合{cell0，cell1}中选择目标小区。在第一定时器运行时，{cell0，cell1}集合中的小区满足切换条件则选为目标小区。在第一定时器运行时，从网络设备接收到第二切换命令，第二切换命令中指示的小区中的cell3也为第一类小区，则终端将cell3添加到优选集合中，并重启第一定时器，在第一定时器运行时，终端在优选集合{cell0，cell1，cell3}中选择目标小区。在第一定时器运行时，{cell0，cell1，cell3}集合中的小区满足切换条件则选为目标小区。
实现方式一中，第一定时器可以理解为是一种终端级别的定时器。对于终端级别的定时器来说，针对不同的小区所起的作用是一样的。另一个可能的设计中，定时器还可以是小区级别的，小区级别的定时器对相应的小区起作用，具体如实现方式二所述。
实现方式二：
如图5所示，定时器针对一个或多个小区进行计时，在定时器运行时，仅允许选择该定时器对应的小区作为目标小区，在定时器超时之后，允许选择除该定时器对应的小区之外的小区作为目标小区。
以下通过两种应用场景来介绍实现方式二。
在第一种应用场景下，终端接收第一切换命令，第一切换命令指示一个或多个第一类小区。以第一切换命令指示第一小区为例，响应于接收到第一切换命令，终端启动针对第一小区计时的定时器，为作区分描述，这里记为第二定时器。在第二定时器运行时，在第一小区中确定目标小区。当第一小区满足第一切换条件时，确定第一小区为目标小区，同时停止第二定时器。在第一定时器超时后，对第一小区的优先选择的保护失效，可以在所有候选目标小区的范围中选择目标小区，即在第一类小区和第二类小区中选择目标小区。
若第一切换命令指示一个第一类小区，则第一小区为第一切换命令所指示的这一个第一类小区。
若第一切换命令指示多个第一类小区，则第一小区为第一切换命令所指示的多个第一类小区中的任意一个小区。在这种情况下，可以针对第一切换命令指示的多个第一类小区分别设置相应的定时器，多个定时器的定时时长可以相同或不同。由于该多个第一类小区的定时器启动时机均为接收到第一切换命令，因此一个可选的方式中，也可以针对第一切换命令指示的多个第一类小区设置一个相同的定时器。假设多个定时器的定时时长相同，不管设置多个定时器还是一个定时器，均记为第二定时器，那么在第二定时器运行时，在第一切换命令所指示的多个第一类小区中选择目标小区，在第二定时器超时后，在所有候选目标小区的范围中选择目标小区。可选的，在第二定时器运行时，选择第一切换命令所指示的多个第一类小区中优先满足切换条件的小区为目标小区，或者，在第二定时器运行时，选择第一切换命令所指示的多个第一类小区中满足切换条件且信道条件最好的小区为目标小区。在第二定时器超时后，允许除第一切换命令所指示的多个第一类小区之外的小区作为目标小区。以第一切换命令指示第一小区为例，在第二定时器超时后，若第一小区先满足切换条件，则将第一小区确定为目标小区，若除第 二小区先满足切换条件，则将第二小区确定为目标小区，第二小区为除第一小区之外的任意候选目标小区。以第一切换命令指示多个第一类小区为例，在第二定时器超时后，若多个第一类小区中的小区先满足切换条件，则将该满足切换条件的小区确定为目标小区，若第二小区先满足切换条件，则将第二小区确定为目标小区，第二小区为除多个第一类小区之外的任意候选目标小区。
举例来说，如图6a所示，第一切换命令指示的多个小区中的cell0和cell1为第一类小区，则在接收到第一切换命令时，针对cell0启动定时器0，针对cell1启动定时器1。其中定时器0和定时器1的定时时长可能相同或不同。图6a以定时器0和定时器1的定时时长相同为例。在定时器0和定时器1运行时，终端在优选集合{cell0，cell1}中选择目标小区，在定时器0和定时器1超时之后，终端在包括{cell0，cell1}的所有候选目标小区中选择目标小区。
如图6b所示，第一切换命令指示的多个小区中的cell0和cell1为第一类小区，则在接收到第一切换命令时，针对cell0和cell1启动定时器0。在定时器0运行时，终端在优选集合{cell0，cell1}中选择目标小区，在定时器0超时之后，终端在包括{cell0，cell1}的所有候选目标小区中选择目标小区。
基于第一种应用场景的描述，在第二种应用场景下，在第二定时器运行时，终端从网络设备接收到第二切换命令，第二切换命令指示一个或多个第一类小区。以第一切换命令指示第三小区为例，响应于接收到第二切换命令，终端启动针对第二小区计时的定时器，为作区分描述，这里记为第三定时器。由于第二定时器还未超时，因此将第三小区加入优选范围。在第二定时器和第三定时器的相交时长内，在包括第三小区在内的优选范围中确定目标小区。若第二定时器超时但第三定时器还未超时，则第一切换命令指示的第一类小区的优选保护失效，在第二切换命令指示的第一类小区中选择目标小区。以第二切换命令指示第三小区为例，当第三小区满足切换条件时，确定第三小区为目标小区。在第三定时器超时后，对第三小区的优先选择的保护失效，可以在包括第三小区在内的所有候选目标小区的范围中选择目标小区，即在第一类小区和第二类小区中选择目标小区。
对于第三小区的理解，若第二切换命令指示的候选目标小区中包括一个第一类小区，则该第三小区为第二切换命令指示的这个第一类小区。
若第二切换命令指示的候选目标小区中包括多个第一类小区，则该第三小区为第二切换命令指示的多个第一类小区中的任意一个小区。在这种情况下，可以针对第二切换命令指示的多个第一类小区分别设置相应的定时器，也可以针对多个第一类小区设置同一个定时器。其中，定时器的设置机制类似于上述对第二定时器的描述，可以参考上述描述，在此不再赘述。
基于上述图6a和图6b的举例，对于第二种应用场景的举例如图7a和图7b所示。
如图7a所示，在图6a所示举例的基础上，在定时器0和定时器1运行时，接收到第二切换命令。第二切换命令指示的候选目标小区中的cell3为第一类小区，在接收到第二切换命令时，针对cell3启动定时器2。定时器2启动后，将cell3加入优选集合，在定时器0和定时器1运行时，定时器0、定时器1和定时器2存在相交的时长，在该相交的时长内，终端在{cell0，cell1，cell3}集合中选择目标小区。可选的，在该相交的时长内，{cell0，cell1，cell3}集合中最先满足切换条件的小区确定为目标小区，或者将{cell0， cell1，cell3}集合中满足切换条件的小区中信道条件最好的小区确定为目标小区。
若定时器0和定时器1超时后，定时器2还未超时，则在定时器0和定时器1超时后，cell0和cell1的优选保护失效，在定时器2运行时终端在{cell3}中选择目标小区。在定时器2超时后，终端在包括{cell3}的所有候选目标小区中选择目标小区。
如图7b所示，在图6b所示举例的基础上，在定时器0运行时，接收到第二切换命令。第二切换命令指示的候选目标小区中的cell3为第一类小区，在接收到第二切换命令时，针对cell3启动定时器2。定时器2启动后，将cell3加入优选集合，在定时器0运行时，定时器0和定时器2存在相交的时长，在该相交的时长内，终端在{cell0，cell1，cell3}集合中选择目标小区。可选的，在该相交的时长内，{cell0，cell1，cell3}集合中最先满足切换条件的小区确定为目标小区，或者将{cell0，cell1，cell3}集合中满足切换条件的小区中信道条件最好的小区确定为目标小区。
若定时器0超时后，定时器2还未超时，则在定时器0超时后，cell0和cell1的优选保护失效，在定时器2运行时终端在{cell3}中选择目标小区。在定时器2超时后，终端在包括{cell3}的所有候选目标小区中选择目标小区。
实现方式三：
如图8a所示，在确定第二小区满足第二切换条件时，启动定时器。在定时器运行时，不允许该第二小区作为目标小区，若存在第一类小区满足切换条件，则将满足切换条件的第一类小区确定为目标小区，同时停止定时器。在定时器超时后，将第二小区确定为目标小区。
实现方式三中的定时器是针对第二小区的。记为第四定时器。
具体的，在接收到第一切换命令后，开始对第一切换命令中的多个候选目标小区进行切换评估。第一切换命令指示的多个候选目标小区中包括第二小区，第二小区为第二类小区。响应于第二小区满足第二切换条件，启动第四定时器。在第四定时器运行时，继续对各个候选目标小区进行测量和评估，一旦确定某一个第一类小区满足了切换条件，例如第一小区满足第一切换条件，将该第一小区确定为目标小区，并停止第四定时器。若在第四定时器运行时，没有第一类小区满足切换条件，则在第四定时器超时后，将第二小区确定为目标小区。有一种情况，若在第四定时器运行时，第二小区不再满足第二切换条件，会终止第四定时器。
第二小区是第二类小区中的任意一个小区，可见实现方式三中的定时器是对第二类小区起作用的，所起作用可以认为是延迟等待作用。在实现方式三中，对多个候选目标小区测量的过程中，一旦有第二类小区先于第一类小区满足切换条件，则启动定时器进行等待计时，在该定时器运行时，继续对各个候选目标小区进行测量，在该定时器超时后，若还未选择出第一类小区满足切换条件，则将该第二类小区作为目标小区。
如图8b所示，实际应用中，在第四定时器运行时，可能会有另一个第二类小区先满足切换条件。例如在第四定时器运行时，确定第四小区满足第四切换条件。第四小区是第二类小区。第四小区可以是第一切换命令指示的，也可能是在第四定时器运行时接收到的第二切换命令指示的。响应于第四小区满足第四切换条件，启动第五定时器。第五定时器是针对于第四小区计时的。在第五定时器运行时，不允许该第四小区作为目标小区，若在第五定时器超时后，还未选出任何小区作为目标小区，则将该第四小区作为目标小区。
第四定时器和第五定时器的相交时长内，不允许该第二小区和第四小区作为目标小区。若在第四定时器超时后，未有第一类小区满足切换条件，则将第二小区确定为目标小区，并终止第五定时器。在第四定时器和第五定时器的运行期间内，若有第一类小区满足切换条件，则将第一类小区确定为目标小区，并终止第四定时器和第五定时器。
对于上述实现方式一～实现方式三，一旦确定目标小区，则停止定时器。
当选择规则为相较于第二类小区优选第一类小区作为目标小区时，终端按照选择规则优先选择第一类小区，由于第一类小区支持在切换过程中与源小区共同服务于终端，这样能够有助于在切换过程中终端与源小区和目标小区均保持连接这一方案的实现。使条件切换方案与eMBB方案能够结合，实现切换过程中的高可靠性和零中断的效果。
以下通过一个具体的实施例来详细说明条件切换与eMBB方案结合的实现方法。
如图9所示，条件切换与eMBB方案结合实现小区切换的具体过程如下所述。
S900、终端与源小区进行数据传输。
S901、终端向源小区发送测量报告，源小区从终端接收测量报告。
测量报告为终端对多个邻小区的测量结果。
S902、源小区进行早期切换判决。
S903、源小区向多个小区发送早期切换请求，多个小区从源小区接收早期切换请求。
图9中仅仅示出了目标小区接收早期切换请求，作为一种示意。
S904、多个小区在接收到早期切换请求后，进行准入控制。
S905、多个小区中的部分或全部分别向源小区返回切换确认消息，源小区从多个小区中的部分或全部接收切换确认消息。
其中，同意接收该终端的小区会返回切换确认消息。
S906、源小区向终端发送切换命令，终端从源小区接收切换命令。
其中，切换命令指示多个候选目标小区。例如，将同意接收该终端的小区均设为候选目标小区。
切换命令可能有一个或多个，其定义和功能如上文中所述的第一切换命令和/或第二切换命令。
S907、终端对切换命令指示的候选目标小区进行评估，并在多个候选目标小区中确定目标小区。
具体确定目标小区的方法如上文中所述。
S908、终端向目标小区发送随机接入前导码，目标小区从终端接收随机接入前导码。
S909、目标小区向终端返回随机接入响应消息，终端从目标小区接收随机接入响应消息。
目标小区在检测到终端发送的前导码后，向终端发送随机接入响应消息。
S910、终端向目标小区发送切换完成消息，目标小区从终端接收切换完成消息。
切换完成消息可以是重配置完成消息。
S911、目标小区向终端发送竞争解决消息。
其中，在S908～S911的随机接入过程中，终端与源小区保持RRC连接，以及用户数据传输。
如果是随机接入信道(random access channel，RACH)-less切换，可以没有步骤S908，S909；如果目标基站为终端分配了专用的随机接入前导码资源，可以没有步骤S911。
终端在接收到切换完成消息后，完成随机接入过程，与目标小区建立RRC连接，并与目标小区进行用户数据传输。
综上，条件切换的方案能够使得源小区通过早期切换判决向终端配置多个候选目标小区，终端对多个候选目标小区进行测量评估，终端自主决定小区切换的时间点，避免切换命令发送过早或过晚导致切换失败的问题，提高了切换过程中的可靠性。通过本申请实施例上述提供的选择准则，终端能够优选第一类小区作为目标小区，能够有助于将条件切换与eMBB方案进行结合。在提高切换过程中的可靠性的基础上，减少切换过程中数据传输中断时间。
基于上述方法实施例，终端在确定目标小区后，向目标小区进行随机接入。向目标小区的随机接入有可能会接入失败。例如，上述方法实施例所描述的条件切换与eMBB的方案，在S908～S911的随机接入过程中，若终端没有收到随机接入响应消息或没有收到竞争解决消息，均会发生随机接入失败。对于RACH-less切换，终端在预配置资源发送RRC重配置消息，如果超过最大时长后仍不能收到竞争解决消息，则判定随机接入失败。
如图10所示，以下描述本申请对于终端向目标小区随机接入失败的解决方法，该方法可以结合上述目标小区的确定方法，也可以单独形成一种方案作为本申请实施例需要保护的方案。
S1001、源小区向终端发送一个或多个RRC消息，终端从源小区接收一个或多个RRC消息。
类似的，图10所示方案中以RRC消息为切换命令进行举例说明。一个或多个切换命令指示多个候选目标小区。
S1002、终端从多个候选目标小区中选择小区1作为目标小区。
其中，终端确定小区1作为目标小区的方法可以按照上述方法实施例中提供的方法，也可以按照其他选择方法。
当该方法单独形成一种方案时，S1001可以为可选步骤。S1001切换命令可以仅指示一个候选目标小区，这种情况下S1002中终端可以确定向该一个候选目标小区发起随机接入的时机。
S1003、终端向小区1发起随机接入过程。
其中，终端在向小区1发起随机接入的过程中，保持与源小区的RRC连接并保持数据传输。
S1004、在向小区1随机接入失败时，终端继续从多个候选目标小区中选择目标小区。
例如，终端从多个候选目标小区中选择小区2作为目标小区。当然，可能该多个候选目标小区中没有符合切换条件的小区作为目标小区，则终端可以继续保持与源小区的连接，并通过源小区进行数据传输。图10以终端选择小区2为目标小区作为示例。若选择小区2为目标小区，则执行S1005。
S1005、终端向小区2发起随机接入过程。
可选的，在向小区2发起随机接入的过程中，终端保持与源小区的RRC连接。
在上述图10所示的解决方法中，在向小区1随机接入失败时，终端可以将小区1从多个候选目标小区中删除，再从删除小区1的候选目标小区中选择小区2；也可以在多个候选目标小区中保留小区1，继续在该多个候选目标小区中选择小区2，这种情况下选择的小区2可能为小区1或者其他小区。
若删除小区1，提供两种可选的实现方法。
(1)终端在向小区1随机接入失败时，向源小区发送第一指示消息。该第一指示消息用于指示向小区1随机接入失败，该第一指示消息中可以携带小区1的标识和/或频率信息。源小区接收到随机接入失败指示消息后，向终端发送第二指示消息，该第二指示消息用于指示终端将小区1从候选目标小区中删除。或者，源小区接收到随机接入失败指示消息后，不向终端发送第二指示消息。终端在未收到第二指示消息的情况下，保留小区1在候选目标小区中，继续对该多个候选目标小区进行测量，以选择小区2。
(2)终端在向小区1随机接入失败时，将小区1从候选目标小区中删除，并向源小区发送第一指示消息。该第一指示消息用于指示向小区1随机接入失败，和/或，用于指示从候选目标小区中删除小区1。第一指示消息中可以携带小区1的标识和/或频率信息。可选的，用于指示向小区1随机接入失败和用于指示从候选目标小区中删除小区1的消息还可以是两条不同的指示消息。
上述删除小区1的两种方法，通过删除小区1，能够避免终端再次对小区1进行随机接入。通过第一指示消息和/或第二指示消息的指示，能够实现终端与源小区两侧的候选目标小区一致。
若保留小区1，终端可以继续对包括小区1在内的多个候选目标小区进行测量。终端可以对小区1的层3(L3)滤波器进行设置，再继续对小区1进行测量。例如，将小区1的L3滤波器重启，或者，将小区1的L3滤波器的滤波系数更新，或者，将小区1的L3滤波重启并更新滤波系数。
其中，终端对小区进行测量的测量模型如图11所示。测量值由物理层(layer1，L1)获得后，经过L1滤波器后上报到高层，在高层经过L3滤波器滤波后，将输出滤波结果输送至评估模块进行评估，获得评估结果。其中L1滤波器属于终端侧实现，并不构成对本专利的限制。
L3滤波器已经被标准化，L3滤波器在滤波时按照如下滤波公式(1)获得滤波结果。
F n＝(1-a)·F n-1+a·M n     公式(1)
其中，M n是L1滤波器最新输出的测量结果；Fn是更新的L3滤波器输出结果，同时也作为评估模块的输入；F n-1是历史L3滤波器输出，F 0被置为M 1。从公式可以得到F 1等于M 1，也就是L1滤波器输出的第一个结果即作为L3滤波器的输出。
a＝1/(2^(k/4)),k是L3滤波系数，不同的测量量可以有不同的k值。
从以上公式(1)中可以看出，如果滤波系数k值增大，相应的a变小，则M n比重变小，F n-1比重变大，所以L3滤波结果会更稳定，波动性更小。反之，滤波系数k值变小，L3滤波结果的波动性更大。
将小区1的L3滤波器重启，即以当前最新测量值为起始点开始进行L3滤波。更新L3滤波系数可以调整历史值和当前值的占比，对于小区1可以采用更稳健的滤波系数，即增加历史值的占比，获得更稳定的滤波结果。更新后的L3滤波系数可以是终端级别 的，也可以是每个候选目标小区单独使用的，可以由源小区指示给终端，或在协议中规定。例如，源小区可以在条件切换命令中配置更新的L3滤波系数，或在其他测量配置消息中配置更新的L3滤波系数。
综上，在向目标小区随机接入失败时，通过保持与源小区的连接，保证用户数据正常传输，并继续对候选目标小区进行评估，以及选择下一个目标小区进行随机接入，保证小区切换正常进行。
在上述实施例的基础上，考虑到源小区可能发生无线链路失败(radio link failure，RLF)，若按照优选第一类小区作为目标小区的选择规则，在切换过程中第一类小区和源小区将会共同服务于终端。由于源小区发生RLF，则终端需要向目标小区发送RLF指示消息，进一步的，目标小区还可能向源小区发送确认消息，该确认消息用于指示取消在切换过程共同服务于该终端。
鉴于此，本申请扩展了选择规则的内容。选择规则还可以包括，在源小区发生RLF的场景下，相较于第一类小区，优先选择第二类小区作为目标小区。这样，当源小区发生RLF时，终端选择第二类小区作为目标小区，在向第二类小区随机接入的过程中，断开与源小区的RRC连接即可。
优选第二类小区作为目标小区的实现方式，可以参照上文中对于优选第一类小区的方式的介绍，将第一类小区与第二类小区互换即可。
基于上述方法实施例的同一构思，如图12所示，本申请实施例还提供一种小区切换的装置1200，该小区切换的装置1200用于执行上述方法实施例中终端执行的操作。该小区切换的装置1200包括处理单元1201和通信单元1202。
通信单元1202，用于从源小区接收一个或多个无线资源控制RRC消息。所述一个或多个RRC消息用于指示多个候选目标小区，所述多个候选目标小区包括第一类小区和第二类小区，所述第一类小区和所述第二类小区的定义参考上文。
处理单元1201，用于按照选择规则，确定目标小区。
此外，小区切换的装置1200中的处理单元1201和通信单元1202还可实现上述方法实施例中终端执行的其它操作或功能，重复之处不再赘述。
基于与上述方法实施例的同一构思，如图13所示，本申请实施例还提供了一种小区切换的装置1300，该小区切换的装置1300用于实现上述方法实施例中终端执行的操作，该小区切换的装置1300包括：收发器1301、处理器1302、存储器1303。存储器1303为可选的。收发器1301用于与其它通信设备进行消息或信令的传输，例如，从源小区接收RRC消息。处理器1302与存储器1303耦合，用于调用存储器1303中的程序，当程序被执行时，使得处理器1302执行上述方法实施例中终端执行的操作。存储器1303用于存储处理器1302执行的程序。图12中的功能模块处理单元1201可以通过处理器1302来实现，通信单元1202可以通过收发器1301来实现。例如，处理器1302执行以下操作：用于按照选择规则，确定目标小区。处理器1302还可以执行上述方法实施例中终端执行的其它操作或功能，重复之处不再赘述。
处理器1302可以是中央处理器(central processing unit，CPU)，网络处理器(network processor，NP)或者CPU和NP的组合。
处理器1302还可以进一步包括硬件芯片。上述硬件芯片可以是专用集成电路(application-specific integrated circuit，ASIC)，可编程逻辑器件(programmable logic device， PLD)或其组合。上述PLD可以是复杂可编程逻辑器件(complex programmable logic device，CPLD)，现场可编程逻辑门阵列(field-programmable gate array，FPGA)，通用阵列逻辑(generic array logic,GAL)或其任意组合。
存储器1303可以包括易失性存储器(volatile memory)，例如随机存取存储器(random-access memory，RAM)；存储器1303也可以包括非易失性存储器(non-volatile memory)，例如快闪存储器(flash memory)，硬盘(hard disk drive，HDD)或固态硬盘(solid-state drive，SSD)；存储器1303还可以包括上述种类的存储器的组合。
在本申请上述方法实施例描述的终端所执行的操作和功能中的部分或全部，可以用芯片或集成电路来完成。
为了实现上述图12或图13所述的小区切换的装置的功能，本申请实施例还提供一种芯片，包括处理器，用于支持该小区切换的装置实现上述方法实施例中终端所涉及的功能。在一种可能的设计中，该芯片与存储器连接或者该芯片包括存储器，该存储器用于保存该小区切换换的装置必要的程序指令和数据。
本申请实施例提供了一种计算机存储介质，存储有计算机程序，该计算机程序包括用于执行上述方法实施例的指令。
本申请实施例提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述方法实施例。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
尽管已描述了本申请的优选实施例，但本领域内的技术人员一旦得知了基本创造性概念，则可对这些实施例作出另外的变更和修改。所以，所附权利要求意欲解释为包括优选实施例以及落入本申请范围的所有变更和修改。
显然，本领域的技术人员可以对本申请实施例进行各种改动和变型而不脱离本申请实施例的精神和范围。这样，倘若本申请实施例的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (21)

  1. 一种小区切换的方法，其特征在于，包括：
    从源小区接收一个或多个无线资源控制RRC消息，所述一个或多个RRC消息用于指示多个候选目标小区，所述多个候选目标小区包括第一类小区和第二类小区，所述第一类小区支持与所述源小区在切换过程中共同服务于终端，所述第二类小区不支持与所述源小区在切换过程中共同服务于所述终端，所述第一类小区包括第一小区，所述第二类小区包括第二小区；
    按照选择规则，确定目标小区，其中，所述选择规则包括：相较于所述第二类小区，优先选择所述第一类小区作为目标小区。
  2. 如权利要求1所述的方法，其特征在于，所述按照选择规则，确定目标小区，包括：
    启动第一定时器；
    在所述第一定时器运行时，在所述第一类小区中确定所述目标小区；在所述第一定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。
  3. 如权利要求2所述的方法，其特征在于，在所述第一定时器运行时，在所述第一类小区中确定所述目标小区，包括：
    在所述第一定时器运行时，若所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区。
  4. 如权利要求2或3所述的方法，其特征在于，在所述第一定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区，包括：
    在所述第一定时器超时后，若所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区，否则，若所述第二小区满足第二切换条件，则确定所述第二小区为所述目标小区。
  5. 如权利要求2或3所述的方法，其特征在于，在所述第一定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区，包括：
    在所述第一定时器超时后，若所述第二小区满足第二切换条件且所述第一小区满足第一切换条件，则确定所述第一小区为所述目标小区。
  6. 如权利要求2～5任一项所述的方法，其特征在于，所述多个RRC消息包括第一RRC消息和第二RRC消息，所述第一RRC消息指示所述第一小区，所述第二RRC消息指示第三小区，所述第三小区属于所述第一类小区；
    所述启动第一定时器，包括：
    响应于接收到所述第一RRC消息，启动所述第一定时器；
    所述方法还包括：
    在所述第一定时器运行时，响应于所述第二RRC消息，重启所述第一定时器。
  7. 如权利要求1所述的方法，其特征在于，所述多个RRC消息包括第一RRC消息，所述第一RRC消息指示所述第一小区；
    所述按照选择规则，确定目标小区，包括：
    响应于接收到所述第一RRC消息，启动第二定时器；
    在所述第二定时器运行时，在所述第一小区中确定所述目标小区，在所述第二定时器 超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。
  8. 如权利要求7所述的方法，其特征在于，所述多个RRC消息还包括第二RRC消息，所述第二RRC消息指示第三小区，所述第三小区为所述第一类小区；
    所述按照选择规则，确定目标小区，包括：
    在所述第二定时器运行时，从所述网络设备接收所述第二RRC消息；
    响应于接收到所述第二RRC消息，启动第三定时器；
    在所述第二定时器和所述第三定时器的相交时长内，在所述第一小区和所述第三小区中确定所述目标小区；在所述第二定时器超时后且所述第三定时器运行时，在所述第三小区中确定所述目标小区；在所述第三定时器超时后，在所述第一类小区和所述第二类小区中确定所述目标小区。
  9. 如权利要求1所述的方法，其特征在于，所述按照选择规则，确定目标小区，包括：
    响应于确定所述第二小区满足第二切换条件，启动第四定时器；
    在所述第四定时器运行时，在所述第一类小区中确定所述目标小区，在所述第四定时器超时后，确定所述第二小区为所述目标小区，其中，所述第二小区满足所述第二切换条件。
  10. 如权利要求9所述的方法，其特征在于，所述方法还包括：
    在所述第四定时器运行时，若确定所述第二小区不满足所述第二切换条件，则终止所述第四定时器。
  11. 如权利要求2～10任一项所述的方法，其特征在于，所述方法还包括：
    响应于确定所述目标小区，终止定时器，所述定时器包括第一定时器、第二定时器、第三定时器或第四定时器中的任一种。
  12. 如权利要求1～11任一项所述的方法，其特征在于，所述第一类小区所属基站与所述源小区所属基站具有直接的通信接口，所述第二类小区所属基站与所述源小区所属基站不具有直接的通信接口；和/或，
    所述第一类小区所属基站与所述源小区所属基站的协议版本相同，所述第二类小区所属基站与所述源小区所属基站的协议版本不同；和/或，
    所述第一类小区支持增强的连接维持eMBB技术，所述第二类小区不支持所述eMBB技术；和/或，
    所述第一类小区与所述源小区的频率不一致，所述第二类小区与所述源小区的频率一致。
  13. 如权利要求1～12任一项所述的方法，其特征在于，所述选择规则还包括：在所述源小区发生无线链路失败的场景下，相较于所述第一类小区，优先选择所述第二类小区作为目标小区。
  14. 如权利要求1～13任一项所述的方法，其特征在于，所述方法还包括：
    保持与所述源小区的RRC连接，并执行向所述目标小区的随机接入的过程。
  15. 如权利要求14所述的方法，其特征在于，若所述随机接入失败，则：
    向所述源小区发送第一指示消息，从所述源小区接收第二指示消息，所述第一指示消息用于指示所述随机接入失败，所述第二指示消息用于指示将所述目标小区从所述多个候选目标小区中删除；或，
    将所述目标小区从所述多个候选目标小区中删除；或，
    重启所述目标小区的层三滤波器；或，
    更新所述目标小区的层三滤波器的滤波系数，并重启所述层三滤波器；或，
    更新所述目标小区的层三滤波器的滤波系数。
  16. 一种小区切换的方法，其特征在于，包括：
    从一个或多个候选目标小区中确定目标小区；
    保持与源小区的无线资源控制RRC连接，执行向所述目标小区的随机接入的过程；
    若所述随机接入失败，则：
    将所述目标小区从所述一个或多个候选目标小区中删除；或，
    重启所述目标小区的层三滤波器；或，
    更新所述目标小区的层三滤波器的滤波系数，并重启所述层三滤波器；或，
    更新所述目标小区的层三滤波器的滤波系数。
  17. 如权利要求16所述的方法，其特征在于，所述方法还包括：
    向所述源小区发送第一指示消息，从所述源小区接收第二指示消息，所述第一指示消息用于指示所述随机接入失败，所述第二指示消息用于指示将所述目标小区从所述一个或多个候选目标小区中删除；
    将所述目标小区从所述一个或多个候选目标小区中删除，包括：
    根据所述第二指示消息，将所述目标小区从所述一个或多个候选目标小区中删除。
  18. 一种小区切换的装置，其特征在于，包括：
    收发器，用于与其它通信设备进行通信；
    处理器，用于与存储器耦合，调用所述存储器中的程序，执行所述程序以实现如权利要求1-17任意一项所述的方法。
  19. 一种计算机可读存储介质，其特征在于，所述计算机存储介质中存储有计算机可读指令，当计算机读取并执行所述计算机可读指令时，使得计算机执行如权利要求1-17任意一项所述的方法。
  20. 一种计算机程序产品，其特征在于，当计算机读取并执行所述计算机程序产品时，使得计算机执行如权利要求1-17任意一项所述的方法。
  21. 一种芯片，其特征在于，所述芯片与存储器相连或者所述芯片包括所述存储器，用于读取并执行所述存储器中存储的软件程序，以实现如权利要求1-17任意一项所述的方法。
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CN1365205A (zh) * 2001-01-11 2002-08-21 华为技术有限公司 码分多址系统中压缩模式的控制方法及其装置
CN101119584A (zh) * 2006-08-03 2008-02-06 中兴通讯股份有限公司 高速下行共享信道同频小区切换的实现方法
WO2009024466A1 (en) * 2007-08-20 2009-02-26 Alcatel Lucent Method of performing a handover and corresponding networks units
CN101594632A (zh) * 2009-06-29 2009-12-02 深圳华为通信技术有限公司 小区切换的方法、装置和系统
CN105208613A (zh) * 2015-09-28 2015-12-30 小米科技有限责任公司 一种小区重选方法及装置
CN107371208A (zh) * 2016-05-13 2017-11-21 中兴通讯股份有限公司 切换方法及装置

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Publication number Priority date Publication date Assignee Title
CN1365205A (zh) * 2001-01-11 2002-08-21 华为技术有限公司 码分多址系统中压缩模式的控制方法及其装置
CN101119584A (zh) * 2006-08-03 2008-02-06 中兴通讯股份有限公司 高速下行共享信道同频小区切换的实现方法
WO2009024466A1 (en) * 2007-08-20 2009-02-26 Alcatel Lucent Method of performing a handover and corresponding networks units
CN101594632A (zh) * 2009-06-29 2009-12-02 深圳华为通信技术有限公司 小区切换的方法、装置和系统
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