CN111294802B

CN111294802B - Cell switching method and device, storage medium, terminal and base station

Info

Publication number: CN111294802B
Application number: CN201910098420.0A
Authority: CN
Inventors: 邓云
Original assignee: Spreadtrum Communications Shanghai Co Ltd
Current assignee: Spreadtrum Communications Shanghai Co Ltd
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2022-11-25
Anticipated expiration: 2039-01-31
Also published as: CN111294802A

Abstract

A cell switching method and device, a storage medium, a terminal and a base station are provided, wherein the cell switching method comprises the following steps: receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources; determining each random access resource based on the parameter configuration information; access to the target cell is attempted on the respective random access resources. By the technical scheme of the invention, the cell switching process deployed in the unlicensed spectrum can be optimized, the switching time delay is reduced, and the user experience is improved.

Description

Cell switching method and device, storage medium, terminal and base station

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a cell switching method and apparatus, a storage medium, a terminal, and a base station.

Background

A Fifth-Generation mobile communication (5G) system adopts a New Radio (NR) technology with a large bandwidth and a high rate, where a maximum bandwidth of a cell may reach 400MHz, which is far greater than a maximum cell bandwidth of 20MHz specified in a Long Term Evolution (LTE) technology. If all NR User Equipments (UE) need to access 400MHz bandwidth when accessing the network, the UE cost will be greatly increased, and the UE power consumption will be increased. Therefore, a new concept of "bandwidth Part (BWP)" is introduced into the 5G system, which allows NR UEs to access the 5G system using narrowband BWP and transmit services using broadband BWP.

For one serving cell, the base station may configure multiple BWPs (e.g., 4 BWPs) for the UE, and typically has at least one BWP, which may allow the idle UE to camp on and may receive system messages and paging messages from the BWPs.

The NR system uses an Unlicensed Spectrum technology, also called New Radio in Unlicensed Spectrum (NR-U) technology. If NR is deployed in unlicensed (also called unlicensed, unlicensed) spectrum, and still continues the communication mechanism of the currently licensed (also called licensed) spectrum, then for the UE, handover needs to be supported in order to meet the mobility requirements of the UE. When accessing a target cell, a UE needs to perform Listen Before Talk (Listen Before Talk, LBT for short) and initiate a random access procedure after obtaining a channel usage right. If the LBT continuously fails, the handover delay is very long, and the handover fails in extreme cases, which causes obvious interruption of communication and reduces user experience.

Disclosure of Invention

The invention solves the technical problem of how to optimize the cell switching process deployed in the unlicensed spectrum so as to reduce the switching time delay and improve the user experience.

To solve the foregoing technical problem, an embodiment of the present invention provides a cell switching method, including: receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources; determining each random access resource based on the parameter configuration information; access to the target cell is attempted on the respective random access resources.

Optionally, the attempting to access the target cell on each random access resource includes: and performing listen-before-talk operation on each unlicensed spectrum resource to which each random access resource belongs to attempt to access the target cell.

Optionally, the handover command further carries information of multiple unlicensed spectrum subbands of the target primary cell, where the two or more random access resources belong to different unlicensed spectrum subbands.

Optionally, the performing listen-before-talk on each unlicensed spectrum resource to which each random access resource belongs to attempt to access the target cell includes: performing listen before talk operation on each unlicensed spectrum sub-band configured with random access resources; determining an unauthorized frequency spectrum sub-band which firstly obtains the channel use right as an access sub-band of a target main cell; transmitting a random access preamble based on random access resources of an access sub-band of the target primary cell to attempt to access the target primary cell.

Optionally, the determining, as the access sub-band of the target primary cell, the unlicensed spectrum sub-band for which the channel usage right is obtained first includes: and when a plurality of unauthorized spectrum sub-bands for obtaining the channel use right firstly are available, selecting the unauthorized spectrum sub-band with the minimum index value as the access sub-band of the target main cell.

Optionally, the taking the unlicensed spectrum sub-band from which the channel usage right is obtained first as the access sub-band of the target primary cell includes: and when a plurality of unauthorized spectrum sub-bands for obtaining the channel use right firstly are available, randomly selecting one unauthorized spectrum sub-band as the access sub-band of the target main cell.

Optionally, the handover command further carries information of a plurality of target serving cells, and the two or more random access resources belong to different target serving cells.

Optionally, the deploying the multiple target serving cells to unlicensed spectrum resources, and performing listen-before-talk operation on each unlicensed spectrum resource to which each random access resource belongs to attempt to access the target cell includes: performing listen before talk operation in each target serving cell configured with random access resources; determining a target serving cell which firstly obtains the channel use right as a target main cell; transmitting a random access preamble based on the random access resource of the target primary cell to attempt to access the target primary cell.

Optionally, after determining as the target primary cell, the method further includes: and if the index value of the target primary cell is not 0, exchanging the index value between the target serving cell with the index value of 0 and the target primary cell in the target serving cell configured with the random access resource so as to change the index value of the target primary cell to 0.

Optionally, the handover command further carries a downlink frequency and a physical cell identifier of each target serving cell, and the method further includes: and taking the downlink frequency and the physical cell identification of the target main cell as parameters of key derivation.

Optionally, the determining, as the target primary cell, the target serving cell that first obtains the channel usage right includes: and when a plurality of target serving cells which obtain the channel use right firstly are available, selecting the target serving cell with the minimum index value as the target primary cell.

Optionally, the determining, as the target primary cell, the target serving cell that first obtains the channel usage right includes: when a plurality of target serving cells which obtain the channel use right firstly are provided, one serving cell is randomly selected as the target primary cell.

Optionally, the parameter configuration information of each random access resource includes one or more of the following items: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing listen before talk operation and the duration of performing listen before talk operation.

To solve the foregoing technical problem, an embodiment of the present invention further provides a cell switching method, including: receiving a switching command, wherein the switching command is from a target cell and carries parameter configuration information of more than two random access resources; and sending the switching command to user equipment so that the user equipment attempts to access a target cell based on the switching command.

Optionally, the parameter configuration information of the random access resource includes one or more of the following items: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing the listen-before-talk operation and the duration of performing the listen-before-talk operation.

To solve the foregoing technical problem, an embodiment of the present invention further provides a cell switching apparatus, including: a receiving module, adapted to receive a handover command, where the handover command carries parameter configuration information of more than two random access resources; a determining module adapted to determine respective random access resources based on the parameter configuration information; and the access module is suitable for trying to access the target cell on each random access resource.

To solve the foregoing technical problem, an embodiment of the present invention further provides a cell switching apparatus, including: a receiving module, adapted to receive a handover command, where the handover command is from a target cell and carries parameter configuration information of more than two random access resources; a sending module adapted to send the handover command to a user equipment, so that the user equipment attempts to access a target cell based on the handover command.

To solve the above technical problem, an embodiment of the present invention further provides a storage medium having stored thereon computer instructions, where the computer instructions execute the steps of the above method when executed.

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a terminal, including a memory and a processor, where the memory stores computer instructions executable on the processor, and the processor executes the computer instructions to perform the steps of the foregoing method.

In order to solve the above technical problem, an embodiment of the present invention further provides a base station, including a memory and a processor, where the memory stores computer instructions executable on the processor, and the processor executes the computer instructions to perform the steps of the above method.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:

the embodiment of the invention provides a cell switching method, which comprises the following steps: receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources; determining each random access resource based on the parameter configuration information; an attempt is made to access the target cell on each random access resource. By the technical scheme provided by the embodiment of the invention, the target cell can be tried to be accessed on a plurality of unauthorized spectrum resources, the success probability of obtaining the channel use right can be improved, the time delay in the switching process on the unauthorized spectrum is reduced, the switching success rate is improved, and the user experience is favorably improved.

Further, the handover command also carries information of multiple unlicensed spectrum subbands of the target primary cell, and the two or more random access resources belong to different unlicensed spectrum subbands. By the technical solution provided by the embodiment of the present invention, random access resources may be configured for multiple unlicensed spectrum subbands (e.g., BWP or a subband narrower than BWP) in the target primary cell, and the number of subbands for performing listen-before-talk operation is increased, thereby further providing possibility for successfully acquiring a channel and accessing the target cell.

Further, the handover command also carries information of a plurality of target serving cells, and the two or more random access resources belong to different target serving cells. Through the technical scheme provided by the embodiment of the invention, a plurality of service cells can be configured for the UE, random access resources are configured in the plurality of service cells to increase the success probability of performing listen before talk operation, and a feasible scheme is further provided for accessing the target cell in time.

Drawings

Fig. 1 is a schematic flow diagram of a cell handover in a prior art NR-U;

fig. 2 is a schematic diagram of spectrum resource partitioning for configuring multiple BWPs for a cell according to an embodiment of the present invention;

fig. 3 is a flowchart illustrating a cell switching method according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a cell handover method according to another embodiment of the present invention;

fig. 5 is a schematic structural diagram of a cell switching apparatus according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of another cell switching apparatus according to an embodiment of the present invention.

Detailed Description

As mentioned in the background, in the prior art, when a UE using unlicensed spectrum resources performs cell handover (from one cell to another cell), if LBT fails to be performed, the cell handover may fail, and communication interruption may be caused.

Specifically, in the 5G system, the BWP in one cell may be divided into an Initial BWP (Initial BWP) and a non-Initial BWP. The initial BWP may be a minimum bandwidth that satisfies the UE access to the 5G system; the non-initial BWP may be broadband and may enable high-speed data transmission. Considering that the network does not know the bandwidth capability of the UE when the UE initially accesses the network, the procedure of initially accessing the network by the UE is generally completed through the initial BWP.

After the UE accesses the network, the bandwidth capability of the UE can be reported to the network, and the network configures non-initial BWP for the UE according to the bandwidth capability of the UE so as to meet the requirement of high-speed data transmission. The network may configure multiple non-initial BWPs, and the specific allocation of which BWP depends on the measurement results of the UE and the loading conditions of the different BWPs. For the UE, the central frequency points of the initial BWP and the non-initial BWP may be different, or the central frequency points may be the same but the bandwidths are different.

In a 5G system, a single cell may contain multiple BWPs, each occupying a limited bandwidth, where typically at least one BWP, such as the initial BWP, may allow an idle UE to camp on. The UE may receive a system message, a paging message, from the initial BWP. The UE may access the network base station through the initial BWP to establish Radio Resource Control (RRC) connection, and further establish a data Radio bearer to perform a service. The network base station may then configure other BWPs for the UE depending on UE capabilities, traffic requirements, etc. The UE may have more than one active BWP, e.g., the UE may be in carrier aggregation state and each serving cell may have one active BWP.

For each BWP, there is a corresponding plurality of parameter configurations. For example, the BWP may be applied only after the UE knows the location of the Physical Resource block occupied by the BWP, and a Control Resource Set (CORESET) configuration, a Physical Downlink Shared Channel (PDSCH) configuration, a Physical Uplink Control Channel (PUCCH) configuration, a Physical Uplink Shared Channel (PUSCH) configuration, a reference signal configuration, a Random Access Channel (RACH) configuration, and so on.

Taking the Release 15 protocol standard of the 3rd Generation Partnership Project (3 GPP) Release 15 as an example, for a serving cell, a base station may configure a plurality of BWPs for a UE, such as 4 BWPs at most, but only one of them is an active BWP, i.e., the UE can only receive Downlink Control Information (DCI) of the base station through the BWP, receive data from the BWP, and send data to the base station through the BWP.

On active BWP, the UE detects its DCI at the configured one or more CORESET. There may be two search spaces per CORESET: a common search space and a UE-specific search space. The UE blindly detects the DCI in a search space according to a certain rule, detects the DCI belonging to the UE according to a Radio Network Temporary Identifier (RNTI for short), and receives data or uploads data according to the DCI. Each UE may have one or more RNTIs. For the same CORESET, the UE may have different detection periods to detect DCI located in a Common search space (Common search space) and a UE specific search space (UE specific search space), i.e., the network may configure the UE to detect DCI in the search spaces according to the period, and the UE does not need to detect DCI located in the search spaces in each slot. The number of candidate DCIs that the UE needs to detect may be one or more for each search space, and thus each search space may be represented by a search space set.

When NR is deployed in an unlicensed spectrum, regardless of uplink or downlink, a Listen Before Talk (LBT) mechanism for channel sensing needs to be executed to obtain a channel usage right of the unlicensed spectrum. Specifically, the basic principle of the LBT mechanism is: before transmitting signaling or data in an unlicensed spectrum, a node determines whether a current Channel is available or not based on an Energy detection (Energy detection) result through a Clear Channel Assessment (CCA) mechanism. Some national or regional regulations specify an Energy detection threshold (Energy detection threshold), and if the node receiving Energy is higher than the specified Energy detection threshold, the channel is considered busy and the channel is not available.

In particular, the base station and/or the UE may perform LBT to monitor a frequency band, where the frequency band may be a frequency band shared by Wireless Local Area Networks (WLANs) signals and NR Networks deployed by other operators. If the band is detected to be busy, waiting is needed; if the band is detected to be free, the band may be used for signaling and data transmission. After a period of use, the spectrum resources of the band need to be released. When the spectrum is used again, the monitoring is needed to acquire the use right of the next spectrum.

It should be noted that the usage restrictions of the unlicensed spectrum resources in different countries or regions are not exactly the same. Taking japan as an example, the maximum time for using unlicensed spectrum resources each time cannot exceed 4 milliseconds (ms), and the allowed time for using the unlicensed spectrum resources in other countries or regions may be slightly longer, but all of them require that the occupied unlicensed spectrum is released after a period of time is occupied, and the next spectrum usage right can be obtained by listening again through the LBT mechanism.

When NR is deployed in unlicensed spectrum, cell handover needs to be supported in order to meet the mobility requirements of the UE if the communication mechanism still continues with the current licensed spectrum (e.g., for the UE, one serving cell can only have one active BWP).

Fig. 1 is a flow diagram of a cell handover in a prior art NR-U. The cell handover involves UE, a source base station and a target base station, and may specifically include the following steps:

firstly, UE accesses a source base station in NR-U, establishes RRC connection, and executes measurement according to the configuration of the source base station, such as measuring the signal quality of a same-frequency adjacent region and the signal quality of a different-frequency adjacent region. And when the reporting condition is met, performing LBT, and after the channel use right is obtained, reporting a measurement report to the source base station, such as reporting measurement results of one or more adjacent cells.

And secondly, the source base station makes a switching decision according to the information such as the measurement report sent by the UE, the cell load and the like, and selects a target cell for switching. The source base station then sends a handover request to the target base station.

And then, the target base station performs access control according to the load state. If the UE is allowed to access, necessary configuration information such as random access parameters, the identification of the UE in the target cell and the like is prepared, and a switching request confirmation message is sent to the source base station. The handover request acknowledgement message includes the configuration information.

Further, the source base station performs LBT, and after acquiring the channel use right, transmits a handover command (i.e., a handover request confirm message) received from the target base station to the UE.

Further, after receiving the handover command, the UE may perform handover according to the handover command. In specific implementation, after performing LBT to acquire the channel usage right, the UE needs to initiate a synchronization and random access procedure to the target base station, where the random access procedure may be 2-step random access or 4-step random access.

Further, after the UE performs the 2-step random access procedure, the UE may send a handover complete signaling to the target base station after performing LBT to obtain the channel usage weight.

In the Cell handover process, the target base station may configure one target serving Cell, that is, a target Primary Cell (PCell), or may configure a plurality of target serving cells when the UE supports carrier aggregation, where one is the target PCell and the others are target Secondary cells (scells). The PCell carries RRC signaling of the UE, transmits paging messages of the UE, and the like, and is different from the secondary cell. One or more BWPs may be included on the target PCell. One of which is the initial BWP or the BWP with index 0. And after receiving the handover command, the UE accesses the target cell through the initial BWP of the target PCell or the BWP with the index of 0. In this process, if the UE cannot perform random access in the target PCell all the time due to LBT failure, not only a large handover delay is caused and user satisfaction is reduced, but also handover failure may be caused due to an excessive access delay caused by LBT.

The embodiment of the invention provides a cell switching method, which comprises the following steps: receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources; determining each random access resource based on the parameter configuration information; access to the target cell is attempted on the respective random access resources. By the technical scheme provided by the embodiment of the invention, the target cell can be tried to be accessed on a plurality of unauthorized spectrum resources, the success probability of obtaining the channel use right can be improved, the time delay in the process of switching on the unauthorized spectrum is reduced, the switching success rate is improved, and the user experience is favorably improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 2 is a schematic diagram of spectrum resource division of a cell configured with multiple BWPs according to an embodiment of the present invention. Referring to fig. 2, a cell is deployed in unlicensed spectrum resources, and includes uplink spectrum resources and downlink spectrum resources, where the uplink spectrum resources and the downlink spectrum resources respectively include 4 BWPs: BWP0, BWP1, BWP2 and BWP3. In practice different BWPs may intersect. The initial BWP is BWP0, the idle UE may reside on BWP0, and the base station sends a System Information (SI), a paging message, and the like on BWP 0. Since the cell is deployed in an unlicensed spectrum, LBT needs to be performed when the base station and the UE transmit signaling or data. If the channel is idle, the base station and the UE can obtain the channel use right in a period of time.

Fig. 3 is a flowchart of a cell handover method according to an embodiment of the present invention, which is configured to handover to a target cell deployed in an unlicensed spectrum. In particular, the cell handover method may be implemented by a user equipment, e.g., an NR-U UE. Specifically, the cell switching method may include the following steps:

step S301, receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources;

step S302, based on the parameter configuration information, determining each random access resource;

step S303, an attempt is made to access the target cell on each random access resource.

Specifically, if the UE reports a measurement report to the source cell, the source cell may make a handover decision according to the measurement report sent by the UE and information such as cell load, select a target cell for handover, and send a handover request to the target cell. Further, if the target cell allows the UE to access, a handover request acknowledgement (i.e., a handover command) may be sent to the source cell. The handover command may include necessary configuration information, and may carry parameter configuration information of at least two random access resources. The source cell may then forward the handover command to the UE after obtaining the channel usage right.

In step S301, the UE may receive the handover command and further learn the parameter configuration information related to multiple (e.g., two or more, i.e., two or more) random access resources.

In a specific implementation, the handover command may further carry information of one or more unlicensed spectrum sub-bands (e.g., unlicensed spectrum BWPs) of the target primary cell, where the two or more random access resources belong to the same or different unlicensed spectrum BWPs. The number of unlicensed spectrum BWPs may be greater than or equal to the number of random access resources. When the number of unlicensed spectrum BWPs is greater than the number of random resources, it means that at least one unlicensed spectrum BWP is not configured with random access resources by the target cell.

As a variation, the handover command may also carry information of multiple target serving cells, and the two or more random access resources belong to different target serving cells. The number of target serving cells may be greater than or equal to the number of random access resources. When the number of the random access resources is less than the number of the target serving cells, it means that some target serving cells are not configured with the random access resources.

In step S302, after the UE knows the parameter configuration information, the UE may determine each random access resource, for example, a time-frequency parameter of the random access resource, time slot information and frequency domain information of a random access Preamble (Preamble), and may further include a length of the random access Preamble, a random access Preamble index, a priority for performing LBT, a duration for performing LBT, and the like. Because the UE needs to perform LBT when accessing the target cell, for different UEs, because the priorities of the established services are different, the target cell may configure different LBT priorities for different UEs, for example, a high-priority LBT may have a shorter LBT duration or a shorter back-off time.

In step S303, the UE may attempt to access the target cell on various (or part of) random access resources. In particular, the UE may perform listen-before-talk operations on the respective unlicensed spectrum resources to which each (or a portion of) the random access resources belong in an attempt to access the target cell. Each random access resource is deployed in an unlicensed spectrum resource. The random access resource may be configured to one or more BWPs in the target primary cell, and may also be configured to a plurality of target serving cells.

In a specific implementation, if the handover command carries information of one unlicensed frequency BWP (i.e. initial BWP) of the target primary cell and more than two random access resources, in this case, one BWP may include multiple sub-bands, and more than two random access resources may be located in different sub-bands, and some sub-bands may not be configured with random access resources. The size of the sub-band may depend on the bandwidth limit for performing LBT, generally the bandwidth for performing LBT may be 5MHz, or 10MHz, or 20MHz, and different countries or different operators may set different bandwidth limits for performing LBT. For example, in a configuration where a BWP has 40MHz and includes 4 sub-bands, each sub-band has 10MHz, the (target) base station and the UE perform independent LBT on each sub-band, if a channel usage right is obtained in a certain sub-band, the resources of the sub-band can be used for data and signaling transmission, at this time, more than two random access resources can be located in the 4 different sub-bands, for example, two random access resources are configured on 2 sub-bands, the UE performs LBT on the unlicensed spectrum sub-band configured with the random access resources according to a handover command, and determines the unlicensed spectrum sub-band where LBT succeeds and the channel usage right is obtained first as the access sub-band of the target primary cell. The UE sends a random access preamble through the sub-band and receives a random access response at a corresponding position according to the random access configuration. If the random access process is 4 steps, after receiving the random access response, the UE sends a switching completion signaling to the target base station according to the uplink authorization configured in the response.

Another possible implementation manner is that one BWP has 40MHz and includes 2 sub-bands, each sub-band has 20MHz, and random access resources are configured on both sub-bands, and the (target) base station and the UE perform LBT according to 20MHz to obtain the channel usage right of the sub-band, and after receiving the handover command, the UE performs LBT on both sub-bands according to the random access configuration, and determines the unlicensed spectrum sub-band where LBT succeeds and the channel usage right is obtained first as the access sub-band of the target primary cell, for example, the initial access sub-band.

In a specific implementation, if the handover command carries information of multiple unlicensed spectrum BWPs of the target primary cell and more than two random access resources, the UE may perform LBT on each unlicensed spectrum BWP configured with random access resources and determine the unlicensed spectrum BWP, for which LBT succeeds and channel usage rights are obtained first, as an initial access BWP of the target primary cell. At this time, the UE and the (target) base station perform independent LBT according to BWP, perform random access in BWP that preferentially obtains channel usage right, access the target cell, and complete the handover procedure.

As a non-limiting example, if there are a plurality of unlicensed spectrum BWPs for which channel usage rights are first obtained, the UE may select the unlicensed spectrum BWP with the smallest index value as the initial access BWP of the target primary cell.

As a variation, if there are a plurality of unlicensed spectrum BWPs for which channel usage rights are obtained first, the UE may randomly select one unlicensed spectrum BWP as an initial access BWP of the target primary cell.

Thereafter, the UE may transmit a random access preamble on a random access resource of an initial access BWP of the target primary cell to attempt to access the target primary cell.

In a specific implementation, if the handover command carries information of a plurality of target serving cells and more than two random access resources belonging to different target serving cells, the UE may attempt to access the target cells. Specifically, the UE may perform LBT in each target serving cell configured with random access resources, and determine a target serving cell from which a channel usage right is first obtained as a target primary cell. If there are multiple target serving cells for which channel usage rights are obtained first, the UE may select a target serving cell with the smallest index value as the target primary cell, or randomly select one serving cell as the target primary cell.

Further, when the index value of the target primary cell is not 0, the UE may perform cell switching, that is, in the target serving cell configured with the random access resource, the target serving cell with an index value of 0 is switched with the index value of the target primary cell, so that the index value of the target primary cell is changed to 0 and the index value of another target serving cell to be switched is changed to the original index value of the target primary cell. In the process of exchanging the index values of the cells, other configuration parameters corresponding to the two cells are kept unchanged, and exchange is not needed.

The UE may then transmit a random access preamble based on the random access resources of the target primary cell to attempt to access the target primary cell. It should be noted that the handover command may also carry the downlink frequency and the physical cell identifier of each target serving cell. After determining the target primary cell, the UE may use the downlink frequency and the physical cell identity of the target primary cell as parameters for key derivation to generate a key applied in the target primary cell.

Fig. 4 is a schematic flowchart of another cell handover according to an embodiment of the present invention. The cell switching method may be implemented by a network side base station, for example, an NR-U base station. Specifically, the cell switching method may include the steps of:

step S401, receiving a switching command, wherein the switching command is from a target cell and carries parameter configuration information of more than two random access resources;

step S402, sending the switching command to the user equipment, so that the user equipment tries to access the target cell based on the switching command.

More specifically, in step S401, if the target cell allows the handover to be performed, the target cell will send a handover command to the base station of the serving cell (i.e. the source base station, the base station currently serving the user equipment). The base station of the serving cell may receive the handover command. The handover command may carry parameter configuration information of more than two random access resources.

In a specific implementation, the parameter configuration information of the random access resource may include one or more of the following items: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of executing LBT and the time length of executing LBT.

In a specific implementation, the handover command may also carry multiple pieces of subband information of the initial BWP of the target primary cell. The more than two random access resources belong to different sub-bands. The number of unlicensed spectrum sub-bands may be greater than the number of random access resources.

In a specific implementation, the handover command may also carry information of multiple unlicensed spectrum BWPs of the target primary cell. The two or more random access resources belong to different unlicensed spectrum BWPs. The number of the unlicensed spectrum BWPs may be greater than the number of the random access resources.

As a variation, the handover command may also carry information of multiple target serving cells, and the two or more random access resources may belong to different target serving cells.

In step S402, the base station of the serving cell may send the handover command to the UE. After receiving the handover command, the UE may attempt to access the target cell, e.g., access the target primary cell, based on the handover command.

Those skilled in the art understand that the steps S401 to S402 can be regarded as execution steps corresponding to the steps S301 to S303 in the embodiment shown in fig. 3, and the two steps are complementary in terms of specific implementation principle and logic. Therefore, the explanation of the terms in this embodiment can refer to the description of the embodiment shown in fig. 3, and will not be repeated here.

The details are explained below with specific examples.

The first embodiment is as follows: and the UE accesses the target PCell by taking the BWP accessed firstly as the initial access BWP.

Taking fig. 2 as an example, assume that the target cell is composed of 4 BWPs, where the initial BWP is BWP0, and the idle UE may camp on BWP 0. The cell is deployed in an unlicensed spectrum.

In a specific implementation, the UE in the connected state performs a service in a serving cell (which may also be referred to as a source cell), performs measurement according to measurement parameters configured in the source cell, and evaluates other cells that meet reporting conditions. After reporting the measurement report, the base station of the source cell (i.e. the source base station) may make a handover decision, such as selecting a target cell containing 4 BWPs, according to the measurement report and the cell load. Thereafter, the source cell may send a handover request to the base station of the target cell (i.e., the target base station); if the target base station allows the UE to be switched, the target base station configures necessary parameters for the UE, generates a switching command, and the source base station sends a request confirmation (namely, the switching command).

Further, the target base station configures 4 BWPs of the target primary cell (PCell) for the UE, and the BWP indexes are BWP0, BWP1, BWP2, and BWP3 as shown in fig. 2. The target base station may configure random access resources on all BWPs, for example, configure random access resources on 3 BWPs of BWP0, BWP1, and BWP 2.

The parameter configuration information of the random access resources may be completely different or partially the same, for example, there are random access resources in the same time slot. The parameter configuration information of the random access resource may include time-frequency parameter configuration, such as time slot information and frequency domain information that may send a random access preamble sequence (also referred to as a random access preamble), and may further include a length of the random access preamble, an index of the random access preamble, a priority for performing LBT, a duration for performing LBT, and the like.

After the UE receives the handover command forwarded by the source base station, when accessing the target PCell, the UE may perform LBT on a plurality of BWPs configured with random access, respectively, select a BWP that first obtains a channel usage right and may transmit a random access preamble (i.e., select a BWP that may first transmit a random access preamble), and use the BWP as an initial access BWP of the access target PCell.

As a non-limiting example, if there are multiple BWPs that can perform random access simultaneously, the UE may randomly select one BWP or select the smallest indexed BWP to perform random access to access the target PCell.

The UE may receive the random access response transmitted by the target base station after the random access preamble is transmitted by the selected BWP. If the handover command configures a random access preamble (index of the random access preamble, i.e. dedicated random access preamble) corresponding to the different BWPs accessed by the UE, the UE indicates that the random access is successful when receiving the random access response. If the handover command does not configure the random access preamble of the UE accessing the target PCell, the UE needs to send a third message to the target base station according to the transmission resource indicated by the random access response after receiving the random access response, and indicates that the random access is successful only when successfully receiving the fourth message sent by the target base station.

By performing random access on the random access resources of multiple BWPs, the UE may select the BWP of the target PCell that is accessed first as the initial access BWP, thereby reducing the handover delay incurred in the handover process, improving the system performance, and improving the user satisfaction.

The second concrete embodiment: and the UE takes the service cell accessed firstly as the PCell.

In general, if a target base station configures a plurality of serving cells for a UE, where one serving cell is a PCell, an index of the cell is 0; the other serving cell is an SCell, whose cell index starts at 1. And the UE is accessed to the PCell during switching, executes a random access process on the PCell and sends a switching completion signaling to the target base station through the PCell. The handover complete signaling is RRC signaling and is configured only in the PCell.

In the embodiment of the present invention, when the target base station configures multiple serving cells for the UE, if the target base station configures 3 serving cells, the target base station is respectively identified by the cell indexes cell index 0, cell index 1, and cell index 2. But the target base station does not need to indicate the cell index 0 as the target PCell. The target base station may configure random access resources in all three cells.

And after the UE receives the switching command, taking the serving cell which can be accessed firstly as the target PCell. The UE performs LBT in all three cells, selects a cell which first obtains a channel usage right and can send a random access preamble as a PCell. For example, if the UE finds that the LBT performed only in the frequency band where the cell Index 1 is located is successful, the UE may send a random access preamble according to the random access resource configuration, take the cell Index 1 as the PCell, and set the cell identifier of the PCell to 0. Further, the UE may set the index of the serving cell, which is originally indexed by 0, to 1, that is, when the UE finds that the cell index that can be accessed to the target cell first is not the cell index 0, the cell indexes may be exchanged, so that the index of the cell that becomes the target PCell is changed to the cell index 0.

In a specific implementation, if the UE finds that channel usage rights can be obtained simultaneously in multiple target serving cells and a random access preamble can be sent, the UE may select one cell for access or select a cell with the smallest cell index for access.

It should be noted that the handover command may also carry the downlink frequency and the physical cell identifier of each target serving cell. After the handover, the derivation of the key is related to the downlink frequency and the physical cell identifier of the PCell, so that after the UE uses the cell that can be accessed first as the PCell, the UE may use the downlink frequency and the physical cell identifier of the selected PCell as the key derivation parameters, and generate the key applied in the target cell according to the manner specified by the protocol.

In view of the above, according to the technical solution provided by the embodiment of the present invention, LBT is performed on multiple BWPs configured with random access in a PCell, or LBT is performed on multiple serving cells configured with random access, and a first channel use right is selected to be obtained, so that a delay in a handover process on an unlicensed spectrum can be reduced, and a handover success rate is improved.

Fig. 5 is a schematic structural diagram of a cell switching apparatus according to an embodiment of the present invention. The cell switching apparatus 5 may be applied to the user equipment side, and is executed by the UE. Those skilled in the art will appreciate that embodiments of the present invention may be used to implement the method aspect illustrated in fig. 3 described above.

Specifically, the cell switching apparatus 5 may include: a receiving module 51, adapted to receive a handover command, where the handover command carries parameter configuration information of more than two random access resources; a determining module 52 adapted to determine respective random access resources based on the parameter configuration information; an access module 53 adapted to attempt to access the target cell on respective random access resources.

In a specific implementation, the access module 53 may include: an executing sub-module 531, adapted to perform listen before talk operation on each unlicensed spectrum resource to which said each random access resource belongs, so as to attempt to access the target cell.

In a specific implementation, the handover command may further carry information of multiple unlicensed spectrum subbands of the target primary cell, where the two or more random access resources belong to different unlicensed spectrum subbands.

In a specific implementation, the execution sub-module 531 may include: a first performing unit 5311 adapted to perform listen before talk operation on each unlicensed spectrum sub-band configured with random access resources; a first determining unit 5312 adapted to determine an unlicensed spectrum sub-band from which channel usage rights are obtained first as an access sub-band of a target primary cell; a first transmitting unit 5313 adapted to transmit a random access preamble based on a random access resource of an access subband of the target primary cell to attempt to access the target primary cell.

In a specific implementation, the first determining unit 5312 may be further configured to select, when there are multiple unlicensed spectrum subbands for which channel usage rights are obtained first, an unlicensed spectrum subband with a smallest index value as the access subband of the target primary cell. Alternatively, the first determining unit 5312 may be further configured to randomly select one unlicensed spectrum sub-band as the access sub-band of the target primary cell when there are multiple unlicensed spectrum sub-bands for which channel usage rights are obtained first.

As a variation, the handover command may also carry information of multiple target serving cells, and the two or more random access resources belong to different target serving cells.

In an implementation, the execution sub-module 531 may include: a second performing unit 5314 adapted to perform listen before talk operation in each target serving cell configured with random access resources; a second determining unit 5315 adapted to determine a target serving cell from which a channel use right is obtained first as a target primary cell; a second transmitting unit 5316 adapted to transmit a random access preamble based on the random access resource of the target primary cell to attempt to access the target primary cell.

In a specific implementation, the cell switching apparatus 5 may further include: a switching module 54. Specifically, if the index value of the target primary cell is not 0, the exchanging module 54 is adapted to exchange an index value with the target primary cell, of the target serving cells configured with the random access resource, of the target serving cells with an index value of 0, so as to change the index value of the target primary cell to 0.

In a specific implementation, the handover command further carries a downlink frequency and a physical cell identifier of each target serving cell, and the cell switching apparatus 5 may further include: a generating module 55, adapted to use the downlink frequency and the physical cell identifier of the target primary cell as parameters for key derivation.

In a specific implementation, the second determining unit 5315 is further adapted to select, as the target primary cell, a target serving cell with a smallest index value when there are a plurality of target serving cells that first obtain channel usage rights. Alternatively, the second determining unit 5315 is further adapted to randomly select one serving cell as the target primary cell when a plurality of target serving cells are obtained first.

In a specific implementation, the parameter configuration information of each random access resource may include one or more of the following items: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing listen before talk operation and the duration of performing listen before talk operation.

For more details of the operation principle and the operation mode of the cell switching device 5, reference may be made to the related description in fig. 3, which is not described herein again.

Fig. 6 is a schematic structural diagram of a cell switching apparatus according to an embodiment of the present invention. The cell switching apparatus 6 may be applied to a network side, for example, executed based on a base station on the network side, and those skilled in the art understand that the embodiment of the present invention may be used to implement the technical solution of the method shown in fig. 4.

Specifically, the cell switching apparatus 6 may include: a receiving module 61, adapted to receive a handover command, where the handover command is from a target cell and carries parameter configuration information of more than two random access resources; a sending module 62, adapted to send the handover command to the user equipment, so that the user equipment attempts to access the target cell based on the handover command.

In a specific implementation, the handover command may also carry information of a plurality of target serving cells, and the two or more random access resources belong to different target serving cells.

In a specific implementation, the parameter configuration information of the random access resource may include one or more of the following items: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing the listen-before-talk operation and the duration of performing the listen-before-talk operation.

For more details of the operation principle and the operation mode of the cell switching device 6, reference may be made to the related description in fig. 4, which is not described herein again.

Further, the embodiment of the present invention also discloses a storage medium, on which computer instructions are stored, and when the computer instructions are executed, the technical solutions of the methods described in the embodiments shown in fig. 3 and fig. 4 are executed. Preferably, the storage medium may include a computer-readable storage medium. The storage medium may include ROM, RAM, magnetic or optical disks, etc.

Further, an embodiment of the present invention further discloses a terminal, which includes a memory and a processor, where the memory stores a computer instruction capable of running on the processor, and the processor executes the technical solution of the method in the embodiment shown in fig. 3 when running the computer instruction. Preferably, the base station may interact with the user equipment, and specifically, the terminal may be a user equipment (i.e., UE).

Further, the embodiment of the present invention further discloses a base station, which includes a memory and a processor, where the memory stores computer instructions capable of being executed on the processor, and the processor executes the technical solution of the method in the embodiment shown in fig. 4 when executing the computer instructions. Specifically, the base station may be an NR base station.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method of cell handover, comprising:

receiving a switching command, wherein the switching command carries parameter configuration information of more than two random access resources;

determining each random access resource based on the parameter configuration information;

attempting to access the target cell on respective random access resources, comprising: and performing listen-before-talk operation on each unlicensed spectrum resource to which each random access resource belongs to attempt to access the target cell.

2. The cell switching method according to claim 1, wherein the handover command further carries information of multiple unlicensed spectrum subbands of the target primary cell, and the two or more random access resources belong to different unlicensed spectrum subbands.

3. The cell handover method according to claim 2, wherein the performing listen-before-talk operation on each unlicensed spectrum resource to which each random access resource belongs to attempt to access a target cell comprises:

performing listen before talk operation on each unlicensed spectrum sub-band configured with random access resources;

determining the unauthorized frequency spectrum sub-band which firstly obtains the channel use right as an access sub-band of a target main cell; transmitting a random access preamble based on random access resources of an access sub-band of the target primary cell to attempt to access the target primary cell.

4. The cell switching method according to claim 3, wherein the determining the unlicensed spectrum sub-band from which the channel usage right is obtained first as the access sub-band of the target primary cell comprises:

and when a plurality of unauthorized spectrum sub-bands for obtaining the channel use right firstly are available, selecting the unauthorized spectrum sub-band with the minimum index value as the access sub-band of the target main cell.

5. The cell switching method according to claim 3, wherein the using the unlicensed spectrum sub-band from which the channel usage right is obtained first as the access sub-band of the target primary cell comprises:

and when a plurality of unauthorized spectrum sub-bands for obtaining the channel use right firstly are available, randomly selecting one unauthorized spectrum sub-band as the access sub-band of the target main cell.

6. The cell switching method according to claim 1, wherein the handover command further carries information of a plurality of target serving cells, and the two or more random access resources belong to different target serving cells.

7. The cell handover method according to claim 6, wherein the target cells are deployed in unlicensed spectrum resources, and wherein the performing listen-before-talk operations on the unlicensed spectrum resources to which the random access resources belong to attempt to access the target cells comprises:

performing listen before talk operation in each target serving cell configured with random access resources;

determining a target serving cell which firstly obtains the channel use right as a target main cell;

transmitting a random access preamble based on the random access resource of the target primary cell to attempt to access the target primary cell.

8. The cell handover method according to claim 7, wherein after determining as the target primary cell, the method further comprises:

and if the index value of the target primary cell is not 0, exchanging the index value between the target serving cell with the index value of 0 and the target primary cell in the target serving cell configured with the random access resource so as to change the index value of the target primary cell to 0.

9. The cell switching method according to claim 8, wherein the handover command further carries a downlink frequency and a physical cell identity of each target serving cell, the method further comprising:

and taking the downlink frequency and the physical cell identification of the target main cell as parameters of key derivation.

10. The cell switching method according to claim 7, wherein the determining the target serving cell that first obtains the channel usage right as the target primary cell comprises:

and when a plurality of target serving cells which obtain the channel use right firstly are available, selecting the target serving cell with the minimum index value as the target primary cell.

11. The cell switching method according to claim 7, wherein the determining the target serving cell that first obtains the channel usage right as the target primary cell comprises:

when a plurality of target service cells which obtain the channel use right firstly are available, one service cell is randomly selected as the target primary cell.

12. The cell switching method according to any of claims 1 to 11, wherein the parameter configuration information of each random access resource comprises one or more of the following: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing listen before talk operation and the duration of performing listen before talk operation.

13. A method of cell handover, comprising:

receiving a switching command, wherein the switching command is from a target cell and carries parameter configuration information of more than two random access resources; the switching command also carries information of a plurality of unauthorized frequency spectrum sub-bands of the target main cell, and the more than two random access resources belong to different unauthorized frequency spectrum sub-bands; and sending the switching command to user equipment so that the user equipment attempts to access a target cell based on the switching command.

14. The cell handover method according to claim 13, wherein the handover command further carries information of a plurality of target serving cells, and the two or more random access resources belong to different target serving cells.

15. The cell switching method according to claim 13 or 14, wherein the parameter configuration information of the random access resource comprises one or more of the following: the time-frequency parameter of the random access resource, the length of the random lead code, the index of the random lead code, the priority of performing listen before talk operation and the duration of performing listen before talk operation.

16. A cell switching apparatus, comprising:

a receiving module, adapted to receive a handover command, where the handover command carries parameter configuration information of more than two random access resources;

a determining module adapted to determine respective random access resources based on the parameter configuration information;

an access module adapted to attempt to access a target cell on respective random access resources, comprising: and performing listen-before-talk operation on each unlicensed spectrum resource to which each random access resource belongs to attempt to access the target cell.

17. A cell switching apparatus, comprising:

a receiving module, adapted to receive a handover command, where the handover command is from a target cell and carries parameter configuration information of more than two random access resources; the switching command also carries information of a plurality of unauthorized frequency spectrum sub-bands of the target main cell, and the more than two random access resources belong to different unauthorized frequency spectrum sub-bands;

a sending module adapted to send the handover command to a user equipment, so that the user equipment attempts to access a target cell based on the handover command.

18. A storage medium having stored thereon computer instructions, which when executed by a processor, perform the steps of the method of any one of claims 1 to 15.

19. A terminal comprising a memory and a processor, the memory having stored thereon computer instructions executable on the processor, wherein the processor, when executing the computer instructions, performs the steps of the method of any one of claims 1 to 12.

20. A base station comprising a memory and a processor, the memory having stored thereon computer instructions executable on the processor, wherein the processor, when executing the computer instructions, performs the steps of the method of any one of claims 13 to 15.