TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of communications technologies, and in particular, to a cell handover method, a method for determining an uplink transmit power, and an apparatus.

BACKGROUND

In a wireless communications system, a mobility technology is a key technology. For a terminal device in a connected state, the terminal device may move between different base stations through a cell handover process.

Currently, a manner for performing cell handover by a terminal device is provided in a long term evolution (LTE) system. In such a manner, a source cell instructs the terminal device to measure the source cell and a target cell of the terminal device. After the measurement, the terminal device autonomously determines, based on an obtained measurement report, whether to perform cell handover.

As can be learned, in such a handover manner, the terminal device autonomously determines whether to perform cell handover, and a disadvantage of such a handover manner is that a network side loses control over the terminal device. In addition, in a process in which the terminal device hands over between two base stations, the base stations need to cooperate with each other. For example, a target base station usually reserves a resource for the terminal device that is to perform a handover. Therefore, if the target base station reserves the resource, but the terminal device never initiates the handover, a waste of resources is caused.

SUMMARY

Embodiments of the present disclosure provide a cell handover method, a method for determining an uplink transmit power, and an apparatus, to strengthen control of a network device over a terminal device.

According to a first aspect, a cell handover method is provided. The method may be performed by a terminal device. The method includes: receiving, by the terminal device, an early handover command sent by a network device, where the early handover command is used to instruct the terminal device to determine whether to perform cell handover; measuring, by the terminal device, a downlink signal sent by the network device and/or a downlink signal sent by another network device, and determining, based on an obtained measurement report and a handover condition that is carried in the early handover command, whether to perform cell handover; and executing, by the terminal device, a handover command if the terminal device receives the handover command sent by the network device, to hand over from a current serving cell to a target cell.

In this embodiment, the terminal device can also perform measurement based on the downlink signal sent by the network device and/or the downlink signal sent by the another network device. In other words, the terminal device can still measure a source cell and the target cell. However, the network device can still send the handover command to the terminal device. If the terminal device receives the handover command sent by the network device, the terminal device performs cell handover by executing the handover command. As can be learned, the network device can control the terminal device, and does not lose control over the terminal device even if the terminal device completely determines whether to perform handover. In addition, if a target base station reserves a resource for the terminal device that is to perform handover, the network device may determine, after comprehensively considering various factors, whether to send the handover command to the terminal device, so that the terminal device can perform cell handover, thereby avoiding a waste of resources.

In one embodiment, the terminal device determines, based on the obtained measurement report and the handover condition if the terminal device does not receive the handover command sent by the network device, whether to perform cell handover.

If the terminal device does not receive the handover command sent by the network device, the terminal device can continue determining whether to perform cell handover, to ensure that the terminal device can complete cell handover as soon as possible, thereby reducing a handover delay.

In one embodiment, before the executing, by the terminal device, a handover command if the terminal device receives the handover command sent by the network device, to hand over from a current serving cell to a target cell, the terminal device determines, based on the obtained measurement report and the handover condition, to perform cell handover.

It may be understood that in this embodiment, a process in which the network device determines whether the terminal device performs cell handover and a process in which the terminal device determines whether the terminal device performs cell handover are both in progress. If either party of the network device and the terminal device determines that the terminal device performs handover, the terminal device executes the determining of the party to perform cell handover. Efficiency of performing cell handover by the terminal device is improved in this manner.

In one embodiment, the terminal device sends, to the network device, the measurement report obtained by measuring the downlink signal sent by the network device and/or the downlink signal sent by the another network device, where the measurement report is used by the network device to determine whether the terminal device needs to perform cell handover.

After obtaining the measurement report, in addition to determining whether the terminal device performs cell handover, the terminal device may further send the measurement report to the network device, and the network device may also determine, based on the measurement report sent by the terminal device, whether the terminal device performs cell handover. In this way, the network device does not need to perform measurement by itself, thereby reducing workload of the network device.

In one embodiment, the terminal device receives uplink configuration information sent by the network device. The terminal device sends an uplink reference signal to the network device based on the uplink configuration information, where the uplink reference signal is used by the network device to determine whether the terminal device needs to perform cell handover.

Alternatively, the network device may determine, based on the measurement report obtained by the network device, whether the terminal device performs cell handover. Therefore, the network device may send the uplink configuration information to the terminal device, to configure the terminal device to send the uplink reference signal to the network device. The network device may measure the uplink reference signal after receiving the uplink reference signal sent by the terminal device, to determine, based on the obtained measurement report, whether the terminal device performs cell handover. The network device obtains the measurement report by itself, so that a determining result of the network device is more accurate and timely.

In one embodiment, the terminal device receives a handover cancel command sent by the network device, where the handover cancel command is used to cancel a function that is configured by the early handover command for the terminal device to determine whether the terminal device performs cell handover. The terminal device executes the handover cancel command, to cancel determining whether the terminal device performs cell handover.

The network device may configure that the terminal device performs conditional handover, or may configure that the terminal device cancels conditional handover. For example, if the network device finds, by monitoring, that channel quality and the like of the terminal device are gradually becoming better, the network device may configure that the terminal device cancels conditional handover, and continue providing a service for the terminal device. In this way, a quantity of times of performing cell handover by the terminal device can be reduced, thereby ensuring service continuity.

In one embodiment, the target cell is determined by the terminal device by measuring the downlink signal sent by the network device and/or the downlink signal sent by the another network device, or the target cell is indicated by the handover command.

When the terminal device performs cell handover, the target cell may be selected by the terminal device based on the measurement report obtained by the terminal device, or may be selected based on the handover command sent by the network device. In other words, the target cell may be determined by the terminal device, or may be determined by the network device. The manners are relatively flexible.

According to a second aspect, a cell handover method is provided. The method may be performed by a network device, and the network device may be, for example, a base station. The method includes: sending, by the network device, an early handover command to a terminal device, where the early handover command is used to instruct the terminal device to determine whether to perform cell handover; determining, by the network device, whether the terminal device needs to perform cell handover; and sending, by the network device, a handover command to the terminal device if the network device determines that the terminal device needs to perform cell handover, where the handover command is used to instruct the terminal device to perform cell handover.

In one embodiment, the network device sends uplink configuration information to the terminal device, where the uplink configuration information is used by the terminal device to send an uplink reference signal to the network device. The network device receives the uplink reference signal sent by the terminal device. The network device measures the uplink reference signal, to obtain a measurement report. The determining, by the network device, whether the terminal device needs to perform cell handover includes: determining, by the network device based on the obtained measurement report, whether the terminal device needs to perform cell handover.

The network device may determine, based on different determining bases, whether the terminal device needs to perform cell handover, and the measurement report that is obtained by the network device by performing measurement and based on which the network device performs determining is one of the determining bases. In such a determining manner, the network device performs determining based on the measurement report obtained by the network device by performing measurement, so that a determining result of the network device is more accurate and timely.

In one embodiment, the network device receives a measurement report sent by the terminal device, where the measurement report is obtained by the terminal device by measuring a downlink signal sent by the network device and/or a downlink signal sent by another network device. The determining, by the network device, whether the terminal device needs to perform cell handover includes: determining, by the network device based on the received measurement report, whether the terminal device needs to perform cell handover.

The foregoing illustrates that the network device may determine, based on different determining bases, whether the terminal device needs to perform cell handover, and the measurement report that is sent by the terminal device and based on which the network device performs determining is another determining basis. In such a determining manner, the network device performs determining based on the measurement report sent by the terminal device, and the network device does not need to perform measurement, thereby reducing workload of the network device.

In one embodiment, the determining, by the network device, whether the terminal device needs to perform cell handover includes: if a timer that is set in the network device expires, determining, by the network device, that the terminal device needs to perform cell handover.

Whether the timer expires is another determining basis on which the network device determines whether the terminal device needs to perform cell handover. Such a manner is relatively simple. It may be determined, provided that the timer expires, that the terminal device needs to perform cell handover, and no extra work needs to be done, thereby reducing a burden of the network device.

In one embodiment, the network device sends a handover cancel command to the terminal device, where the handover cancel command is used to instruct the terminal device to stop determining whether to perform cell handover.

In one embodiment, the handover command carries a cell identifier, where the cell identifier is an identifier of a cell to which the terminal device can hand over.

The handover command sent by the network device to the terminal device may carry the cell identifier, and the terminal device may select a target cell based on the cell identifier sent by the network device, so that the terminal device can work under control of the network device, thereby strengthening control of the network device.

According to a third aspect, a cell handover method is provided. The method may be performed by a terminal device. The method includes: receiving, by the terminal device, an early handover command sent by a network device, where the early handover command is used to instruct the terminal device to determine whether to perform cell handover, the early handover command carries a cell identifier, the cell identifier is determined by the network device by measuring an uplink signal sent by the terminal device, and the cell identifier is an identifier of a cell to which the terminal device can hand over. The terminal device measures a downlink signal sent by the network device and/or a downlink signal sent by another network device, and determines, based on an obtained measurement report and a handover condition that is carried in the early handover command, whether to perform cell handover. The terminal device hands over from a current serving cell to a target cell, where the target cell is determined by the terminal device based on the obtained measurement report and/or the received cell identifier.

In this embodiment, the terminal device may perform conditional handover, and the network device may measure an uplink reference signal sent by the terminal device, to determine the cell identifier. The terminal device may select a best cell, as the target cell, from cells whose cell identifiers are sent by the network device and/or cells whose cell identifiers are determined by the terminal device, so that a selection range of the target cell is wider, and it is more helpful to select a cell having better performance.

In one embodiment, if the target cell is determined by the terminal device based on the received cell identifier, before the terminal device hands over from the current serving cell to the target cell, the terminal device receives a handover command sent by the network device, where the handover command is used to instruct the terminal device to perform cell handover.

The network device may determine whether the terminal device needs to perform cell handover. If the network device determines that the terminal device needs to perform cell handover, the network device may directly send the handover command to the terminal device, and the terminal device may directly execute the handover command sent by the network device, to perform cell handover. Moreover, the terminal device may select the target cell from the cells whose cell identifiers are sent by the network device, thereby strengthening control of the network device, and reducing a handover delay.

According to a fourth aspect, a cell handover method is provided. The method may be performed by a network device, and the network device may be, for example, a base station. The method includes: receiving, by the network device, an uplink reference signal sent by a terminal device; measuring, by the network device, the uplink reference signal, to obtain a measurement report; determining, by the network device, a cell identifier based on the measurement report, where the cell identifier is an identifier of a cell to which the terminal device can hand over; and sending, by the network device, an early handover command to the terminal device, where the early handover command is used to instruct the terminal device to determine whether to perform cell handover, and the early handover command carries the cell identifier.

The network device may measure the uplink reference signal sent by the terminal device, to determine the cell identifier. The terminal device may select a best cell, as a target cell, from cells whose cell identifiers are sent by the network device and/or cells whose cell identifiers are determined by the terminal device, so that a selection range of the target cell is wider, and it is more helpful to select a cell having better performance.

In one embodiment, the network device sends a handover command to the terminal device, where the handover command is used to instruct the terminal device to perform cell handover.

According to a fifth aspect, a method for determining an uplink transmit power is provided. The method may be performed by a network device, and the network device is a target network device, that is, a network device to which a terminal device hands over. The target network device may be, for example, a base station. The method includes: before the terminal device hands over to the target network device, determining, by the target network device, an uplink transmit power of the terminal device; and sending, by the target network device, reference information to a source network device currently accessed by the terminal device, where the reference information is used to indicate the uplink transmit power of the terminal device.

In this embodiment, a target cell may determine an uplink transmit power of the terminal device after the handover, so that the determined uplink transmit power is more accurate.

In one embodiment, the reference information includes an offset and/or an uplink path loss. The offset is an offset based on an initial transmit power of the terminal device, and the uplink path loss is a path loss between the terminal device and the target network device.

By using the offset and/or the uplink path loss, the terminal device can obtain the uplink transmit power after the handover.

In one embodiment, the determining, by the target network device, an uplink transmit power of the terminal device includes: receiving, by the target network device, an uplink reference signal sent by the terminal device, and determining, by the target network device, the uplink transmit power based on a transmit power for the uplink reference signal.

The target network device may directly receive the uplink reference signal sent by the terminal device, or may obtain, from the source network device, the uplink reference signal sent by the terminal device. This is not limited in this embodiment.

In one embodiment, after the terminal device hands over to the target network device, the target network device receives a message sent by the terminal device at the uplink transmit power.

The terminal device has determined the uplink transmit power after the handover. After handing over to the target network device, the terminal device may send a message to the target network device at the determined uplink transmit power, thereby improving a success rate of message sending.

According to a sixth aspect, a method for determining an uplink transmit power is provided. The method may be performed by a terminal device. The method includes: before handing over to a target network device, receiving, by the terminal device, reference information sent by a source network device, where the reference information is used to indicate an uplink transmit power at which the terminal device sends a message to the target network device; and determining, by the terminal device based on the reference information, the uplink transmit power at which the terminal device sends a message to the target network device.

In one embodiment, the reference information includes an offset and/or an uplink path loss. The offset is an offset based on an initial transmit power of the terminal device, and the uplink path loss is a path loss between the terminal device and the target network device.

In one embodiment, after handing over to the target network device, the terminal device sends a message to the target network device at the uplink transmit power.

According to a seventh aspect, a cell handover method is provided. The method may be performed by a terminal device. The method includes: receiving, by the terminal device, an early handover command sent by a network device, where the early handover command is used to instruct the terminal device to determine whether to perform cell handover; and if a reporting condition of a measurement report is met before a handover condition carried in the early handover command, sending, by the terminal device, the measurement report to the network device, where the measurement report is obtained by the terminal device by measuring a downlink signal sent by the network device and/or a downlink signal sent by another network device.

In this way, the network device and/or the terminal device may determine in time whether the terminal device performs cell handover, so that the terminal device may perform cell handover as soon as possible.

In one embodiment, if the handover condition carried in the early handover command is met before the reporting condition of the measurement report, or the handover condition carried in the early handover command and the reporting condition of the measurement report are simultaneously met, the terminal device hands over from a current serving cell to a target cell.

That is, the terminal device preferentially performs cell handover. The terminal device performs cell handover provided that the terminal device or the network device determines that the terminal device can perform cell handover, thereby reducing a handover delay.

According to an eighth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the terminal device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a receiving unit and a processing unit. In another embodiment, the specific structure of the communications apparatus may further include a sending unit. The receiving unit, the processing unit, and the sending unit may perform corresponding functions in the method according to the first aspect or any embodiment of the first aspect.

According to a ninth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the network device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a sending unit and a processing unit. In another embodiment, the specific structure of the communications apparatus may further include a receiving unit. The receiving unit, the sending unit, and the processing unit may perform corresponding functions in the method according to the second aspect or any embodiment of the second aspect.

According to a tenth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the terminal device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a receiving unit and a processing unit. The receiving unit and the processing unit may perform corresponding functions in the method according to the third aspect or any embodiment of the third aspect.

According to an eleventh aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the network device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a receiving unit, a processing unit, and a sending unit. The receiving unit, the processing unit, and the sending unit may perform corresponding functions in the method according to the fourth aspect or any embodiment of the fourth aspect.

According to a twelfth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the network device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a sending unit and a processing unit. In another embodiment, the specific structure of the communications apparatus may include a receiving unit. The receiving unit, the processing unit, and the sending unit may perform corresponding functions in the method according to the fifth aspect or any embodiment of the fifth aspect.

According to a thirteenth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the terminal device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a receiving unit and a processing unit. In another embodiment, the specific structure of the communications apparatus may include a sending unit. The receiving unit, the processing unit, and the sending unit may perform corresponding functions in the method according to the sixth aspect or any embodiment of the sixth aspect.

According to a fourteenth aspect, a communications apparatus is provided. The communications apparatus has functions for implementing the terminal device in the foregoing method design. These functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the functions.

In one embodiment, a specific structure of the communications apparatus may include a receiving unit and a sending unit. In another embodiment, the specific structure of the communications apparatus may include a processing unit. The receiving unit, the processing unit, and the sending unit may perform corresponding functions in the method according to the seventh aspect or any embodiment of the seventh aspect.

According to a fifteenth aspect, a communications apparatus is provided. The communications apparatus may be a terminal device, or may be a functional module such as a chip disposed in a terminal device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the terminal device according to the first aspect or any embodiment of the first aspect.

According to a sixteenth aspect, a communications apparatus is provided. The communications apparatus may be a network device, or may be a functional module such as a chip disposed in a network device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the network device according to the second aspect or any embodiment of the second aspect.

According to a seventeenth aspect, a communications apparatus is provided. The communications apparatus may be a terminal device, or may be a functional module such as a chip disposed in a terminal device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the terminal device according to the third aspect or any embodiment of the third aspect.

According to an eighteenth aspect, a communications apparatus is provided. The communications apparatus may be a network device, or may be a functional module such as a chip disposed in a network device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the network device according to the fourth aspect or any embodiment of the fourth aspect.

According to a nineteenth aspect, a communications apparatus is provided. The communications apparatus may be a network device, or may be a functional module such as a chip disposed in a network device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the target network device according to the fifth aspect or any embodiment of the fifth aspect.

According to a twentieth aspect, a communications apparatus is provided. The communications apparatus may be a terminal device, or may be a functional module such as a chip disposed in a terminal device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the terminal device according to the sixth aspect or any embodiment of the sixth aspect.

According to a twenty-first aspect, a communications apparatus is provided. The communications apparatus may be a terminal device, or may be a functional module such as a chip disposed in a terminal device. The communications apparatus includes: a memory configured to store computer-executable program code, a communications interface, and a processor. The processor is coupled to the memory and the communications interface. The program code stored in the memory includes an instruction. When the processor executes the instruction, the instruction enables the communications apparatus to perform the method performed by the terminal device according to the seventh aspect or any embodiment of the seventh aspect.

According to a twenty-second aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the eighth aspect or the communications apparatus described in the fifteenth aspect. The computer software instructions include a program designed for the terminal device according to the first aspect or any embodiment of the first aspect.

According to a twenty-third aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the ninth aspect or the communications apparatus described in the sixteenth aspect. The computer software instructions include a program designed for the network device according to the second aspect or any embodiment of the second aspect.

According to a twenty-fourth aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the tenth aspect or the communications apparatus described in the seventeenth aspect. The computer software instructions include a program designed for the terminal device according to the third aspect or any embodiment of the third aspect.

According to a twenty-fifth aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the eleventh aspect or the communications apparatus described in the eighteenth aspect. The computer software instructions include a program designed for the network device according to the fourth aspect or any embodiment of the fourth aspect.

According to a twenty-sixth aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the twelfth aspect or the communications apparatus described in the nineteenth aspect. The computer software instructions include a program designed for the network device according to the fifth aspect or any embodiment of the fifth aspect.

According to a twenty-seventh aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the thirteenth aspect or the communications apparatus described in the twentieth aspect. The computer software instructions include a program designed for the terminal device according to the sixth aspect or any embodiment of the sixth aspect.

According to a twenty-eighth aspect, a computer storage medium is provided, configured to store computer software instructions used by the communications apparatus described in the fourteenth aspect or the communications apparatus described in the twenty-first aspect. The computer software instructions include a program designed for the terminal device according to the seventh aspect or any embodiment of the seventh aspect.

According to a twenty-ninth aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the first aspect or any embodiment of the first aspect.

According to a thirtieth aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the second aspect or any embodiment of the second aspect.

According to a thirty-first aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the third aspect or any embodiment of the third aspect.

According to a thirty-second aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the fourth aspect or any embodiment of the fourth aspect.

According to a thirty-third aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the fifth aspect or any embodiment of the fifth aspect.

According to a thirty-fourth aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the sixth aspect or any embodiment of the sixth aspect.

According to a thirty-fifth aspect, a computer program product including an instruction is provided. When the computer program product is run on a computer, the computer is enabled to perform the method according to the seventh aspect or any embodiment of the seventh aspect.

In the embodiments described herein, the network device can control the terminal device, and does not lose control over the terminal device even if the terminal device completely determines whether to perform handover.

