EP3925297A1

EP3925297A1 - Primary cell change

Info

Publication number: EP3925297A1
Application number: EP19915492.3A
Authority: EP
Inventors: Chunli Wu; Jing He; Samuli Turtinen; Jarkko Koskela; Tero Henttonen
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2019-02-14
Filing date: 2019-03-28
Publication date: 2021-12-22
Also published as: CN113455049B; EP3925297A4; WO2020164070A1; WO2020164177A1; CN113455049A

Abstract

Example embodiments of the present disclosure relate to devices, methods, apparatuses and computer readable storage media of a primary cell change. In example embodiments, a network device transmits a set of pre-configurations to a terminal device via a first message. At least one pre-configuration in the set of pre-configurations is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell. The network device transmits, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell. In response to receiving a confirmation for the switching from the terminal device, the network device causes the at least one pre-configuration associated with the secondary cell to be activated.

Description

PRIMARY CELL CHANGE

FIELD

Example embodiments of the present disclosure generally relate to the field of communications, and in particular, to devices, methods, apparatuses and computer readable storage media of a primary cell change.

BACKGROUND

An unlicensed spectrum is approved for the fifth generation (5G) New Radio (NR) in many scenarios such as Carrier Aggregation (CA) , Dual Connectivity (DC) , stand-alone (SA) NR-Unlicensed (NR-U) and stand-alone NR. For example, NR may operate in an unlicensed spectrum as a secondary cell (for example, SCell) in CA, as a primary secondary cell (for example, PSCell) in DC, and as a primary cell (for example, PCell) in stand-alone deployment.
For channel access in the unlicensed spectrum, a LTE-Licensed Assisted Access (LAA) Listen Before Talk (LBT) mechanism is adopted as baseline for a 5GHz band and adopted as a starting point of the design for a 6GHz band. At least for a band (for example, sub-7 GHz) where NR-U is operating and absence of Wi-Fi cannot be guaranteed (for example by regulation) , LBT can be performed in a unit of 20 MHz if the baseline assumption is that the NR-U operating bandwidth is an integer multiple of 20MHz.
Typically, Hybrid Automatic Repeat Request (HARQ) feedbacks for Physical Downlink Share Channels (PDSCHs) of SCells need to be sent on a Physical Uplink Control Channel (PUCCH) in a PCell or PSCell (if not mapped to PUCCH SCell) . Thus, a LBT failure in the PCell would block the HARQ feedback for the SCell and therefore impact the throughput even though the SCell is not overloaded.
SUMMARY
In general, example embodiments of the present disclosure provide devices, methods, apparatuses and computer readable storage media of a primary cell change.
In a first aspect, a device is provided which comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the device to transmit a set of pre-configurations to a terminal device via a first message. At least one pre-configuration in the set of pre-configurations is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell. The device is further caused to transmit, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell. The device is caused to in response to receiving a confirmation for the switching from the terminal device, cause the at least one pre-configuration associated with the secondary cell to be activated.
In a second aspect, a device is provided which comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the device to receive a set of pre-configurations from a network device via a first message. At least one pre-configuration in the set of pre-configurations is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell. The device is further caused to receive, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell and transmit a confirmation for the switching to the network device.
In a third aspect, a method is provided. In the method, a network device transmits a set of pre-configurations to a terminal device via a first message. At least one pre-configuration in the set of at least one pre-configuration is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell. The network device transmits, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell. In response to receiving a confirmation for the switching from the terminal device, the network device causes the at least one pre-configuration associated with the secondary cell to be activated.
In a fourth aspect, a method is provided. In the method, a terminal device receives a set of pre-configurations from a network device via a first message. At least one pre-configuration in the set of at least one pre-configuration is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell. The terminal device receives, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell and transmits a confirmation for the switching to the network device.
In a fifth aspect, there is provided an apparatus comprising means for performing the method according to the third or fourth aspect.
In a sixth aspect, there is provided a computer readable storage medium comprising program instructions stored thereon. The instructions, when executed by a processor of a device, cause the device to perform the method according to the third or fourth aspect.
It is to be understood that the summary section is not intended to identify key or essential features of example embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:
FIG. 1 illustrates an example scenario in which some example embodiments of the present disclosure can be implemented;
FIG. 2 illustrates a signaling flow between a network device and a terminal device for a primary cell switch according to some example embodiments of the present disclosure;
FIG. 3 illustrates a flowchart of an example method according to some example embodiments of the present disclosure;
FIG. 4 illustrates a flowchart of an example method according to some other example embodiments of the present disclosure; and
FIG. 5 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure.
Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these example embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.
In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.
As used herein, the term “terminal device” or “user equipment” (UE) refers to any terminal device capable of wireless communications with each other or with the base station. The communications may involve transmitting and/or receiving wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for conveying information over air. In some example embodiments, the UE may be configured to transmit and/or receive information without direct human interaction. For example, the UE may transmit information to the network device on predetermined schedules, when triggered by an internal or external event, or in response to requests from the network side.
Examples of the UE include, but are not limited to, user equipment (UE) such as smart phones, wireless-enabled tablet computers, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , wireless customer-premises equipment (CPE) , sensors, metering devices, personal wearables such as watches etc., and/or vehicles that are capable of communication. For the purpose of discussion, some example embodiments will be described with reference to UEs as examples of the terminal devices, and the terms “terminal device” and “user equipment” (UE) may be used interchangeably in the context of the present disclosure.
As used herein, the term “network device” refers to a device via which services can be provided to a terminal device in a communication network. The network device may comprise an access network device and a core network device. The access network device may comprise any suitable device via which a terminal device or UE can access the communication network. Examples of the access network devices include a relay, an access point (AP) , a transmission point (TRP) , a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a New Radio (NR) NodeB (gNB) , a Remote Radio Module (RRU) , a radio header (RH) , a remote radio head (RRH) , a low power node such as a femto, a pico, and the like.
The core network device may comprise any suitable device capable of communicating with the access network device and providing services to the terminal device in a core network. Examples of the core network device may include Mobile Switching Centers (MSCs) , MMEs, Operation and Management (O&M) nodes, Operation Support System (OSS) nodes, Self-Organization Network (SON) nodes, positioning nodes, such as Enhanced Serving Mobile Location Centers (E-SMLCs) , Mobile Data Terminals (MDTs) , Common Control Network Function (CCNF) , Access and mobility Management Function (AMF) , and/or Network Slice Selection Function (NSSF) .
As used herein, the term “primary cell” or “master cell” refers to a cell of a plurality of serving cells for a terminal device that operates on a dominant carrier and supports cell configuration, cell activation and cell setup of the terminal device. In the context of present disclosure, the primary cell may comprise a PCell in a master cell group (MCG) or a PSCell in secondary cell group (SCG) . For the purpose of discussion, the terms “primary cell” or “master cell” may be used interchangeably in the context of the present disclosure.
As used herein, the term “secondary cell” refers to a cell of the serving cells for a terminal device that operates on a secondary carrier and assists the primary cell in providing additional services to the terminal device. The secondary cell may comprise a SCell.
As used herein, the term “circuitry” may refer to one or more or all of the following:
(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and
(b) combinations of hardware circuits and software, such as (as applicable) : (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and
(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.
This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.
As used herein, the singular forms “a” , “an” , and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to” . The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.
As used herein, the terms “first” , “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be referred to as a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.
The unlicensed spectrum may be applied in many scenarios for in 5G NR. For example, the following scenarios are covered:
· Scenario A: Carrier aggregation (CA) between licensed band NR (Primary cell or PCell) and NR-U (Secondary Cell or SCell) .
о NR-U SCell may have both Downlink (DL) and Uplink (UL) , or DL-only.
о In this scenario, NR PCell is connected to 5G Core Network (5G-CN) .
· Scenario B: Dual connectivity (DC) between licensed band Long Term Evolution (LTE) (PCell) and NR-U (PSCell)
о In this scenario, LTE PCell connected to Evolved Packet Core (EPC) has a higher priority than PCell connected to 5G-CN.
· Scenario C: Stand-alone (SA) NR-U
о In this scenario, NR-U is connected to 5G-CN.
· Scenario D: A stand-alone NR cell in an unlicensed band and UL in a licensed band (single cell architecture)
о In this scenario, NR-U is connected to 5G-CN.
· Scenario E: Dual connectivity between licensed band NR and NR-U
о In this scenario, PCell is connected to 5G-CN, which may be treated with a lower priority.
Accordingly, NR may be allowed to operate in the unlicensed spectrum, for example, in CA with a licensed band NR carrier (s) , in DC with LTE or NR in a licensed band, in stand-alone (SA) with DL and UL in an unlicensed band, and in SA with DL in an unlicensed band and UL in a licensed band.
If absence of Wi-Fi cannot be guaranteed by regulation, for example, in the band (sub-7 GHz) where NR-U is operating, the baseline assumption is that the NR-U operating bandwidth is an integer multiple of 20MHz. For wideband operation for both DL and UL, a bandwidth larger than 20 MHz can be supported with multiple serving cells. NR-U should support that a serving cell can be configured with a bandwidth larger than 20 MHz.
As described above, the agreed SA and DC scenarios in NR-U supports the CA of PCell (in an unlicensed band) + SCells (in an unlicensed band) and the CA of PSCell (in an unlicensed band) + SCells (in an unlicensed band) . Typically, HARQ feedbacks for PDSCHs of SCells need to be sent on a PUCCH in a PCell or PSCell (if not mapped to PUCCH SCell) . However, the loads could be different on different carriers, and LBT cannot always be successful on the unlicensed carriers of a PCell or PSCell together with one or more unlicensed carriers of configured SCells. In this case, an LBT failure in the PCell would block the HARQ feedback for the SCell and therefore impact the throughput even though the SCell is not overloaded.
A conventional approach is handover (HO) via Radio Resource Control (RRC) Reconfiguration with synchronization (sync) to change one available SCell to be a PCell or PSCell. For example, UE may perform RRC connection reestablishment to select one SCell to be the PCell when the original PCell is failed. Such conditional HO from PCell to Scell is performed by the UE when a certain condition is met without an indication from a network side. However, such a HO procedure is slow, and thus may not meet performance requirements, especially in a NR-U system. In NR-U, a time for occupying an unlicensed carrier upon an LBT success is limited by regulatory. The inventors notice that it may be needed to minimize an interruption time for a SCell when the SCell is not overloaded while the PCell is not available anymore.
Example embodiments of the present disclosure provide a fast primary cell (for example, a PCell or PSCell) change or switch in NR-U CA and dual connectivity (DC) , for example. According to example embodiments of the present disclosure, a set of secondary cells are preconfigured as potential primary cells with necessary pre-configurations that can be used when a secondary cell is switched to be a primary cell. A network device indicates the pre-configurations (such as resources, timers, security keys and the like) for the secondary cells to a terminal device. As such, the pre-configurations may be stored at both the network device and the terminal device and activated when a fast primary cell change is enforced.
When it is determined to switch a secondary cell of the secondary cells to be a primary cell, the network device transmits a switch indication to the terminal device. If the network device receives a confirmation for the switching from the terminal device, the network device can cause the at least one pre-configuration associated with the secondary cell to be activated to switch the secondary cell to be the primary cell.
The fast primary cell change or switch may be implemented via downlink user plane (UP) command such as a Media Access Control (MAC) control element (CE) or a Physical Downlink Control Channel (PDCCH) order.
In this way, when continuous LBT failures occur on a primary cell (for example, a PCell or PSCell) , a secondary cell (for example, a SCell) may be switched as a primary cell. Thus, it is avoided that the unavailability of the PCell or PSCell in long time due to LBT failures causes available SCells unable to work due to lack of UL resources for HARQ feedbacks. Moreover, compared with a HO procedure via RRC signaling, transmission delay may be reduced without User Plane (UP) interruption.
The fast primary cell change/switch according to example embodiments of the present disclosure is relevant to both the unlicensed and licensed bands for DC and CA for the low latency and fast recovery objectives as below:
· Efficient and low latency serving cell configuration, activation and setup: minimizing signaling overhead and latency needed for initial cell setup, additional cell setup and additional cell activation for data transmission
о This objective applies to Multiple Radio Access Technology (Multi-RAT) DC (MR-DC) , NR-NR DC and CA.
о The objective should consider enhancements when starting from IDLE, INACTIVE and CONNECTED modes.
· Fast recovery: supporting fast recovery of a master cell group (MCG) link, for example, by utilizing a secondary cell group (SCG) link and splitting signaling radio bearers (SRBs) for recovery during MCG failure while operating under MR-DC
о This objective applies to MR-DC and NR-NR DC.
FIG. 1 shows an example environment 100 in which example embodiments of the present disclosure can be implemented. The environment 100, which may be a part of a communication network, comprises a network device 105 and a terminal device 110. It is to be understood that one network device and one terminal device are shown in the environment 100 only for the purpose of illustration, without suggesting any limitation to the scope of the present disclosure. Any suitable number of network devices and terminal devices may be included in the environment 100.
The network device 105 can provide a primary cell 115 and two secondary cells 120-1 and 120-2 (collectively or individually referred to as a secondary cell 120) as serving cells for the terminal device 110. The primary cell 115 and the secondary cell 120 operate on different carriers.
It is to be understood that the two secondary cells 120 are shown only for the purpose of illustration without suggesting any limitations. The serving cells for the terminal device 110 may comprise any suitable number of secondary cells. It is also to be understood that the serving cells are serviced or provided by one network device only for the purpose of illustration without suggesting any limitations. The serving cells may be serviced by any suitable number of network devices. For example, it may be possible that the primary cell 115 is serviced by a network device, and the secondary cells 120 are serviced by one or more further network devices. As another example, the primary cell 115 and one secondary cell 120-1 are served by one network device, and the other secondary cell 120-2 is served by another network device.
The terminal device 110 can communicate with the network device 105 or with another terminal device (not shown) directly or via the network device 105. The communication may follow any suitable communication standards or protocols such as Universal Mobile Telecommunications System (UMTS) , long term evolution (LTE) , LTE-Advanced (LTE-A) , the fifth generation (5G) NR, Wireless Fidelity (Wi-Fi) and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employs any suitable communication technologies, including, for example, Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiplexing (OFDM) , time division multiplexing (TDM) , frequency division multiplexing (FDM) , code division multiplexing (CDM) , Bluetooth, ZigBee, and machine type communication (MTC) , enhanced mobile broadband (eMBB) , massive machine type communication (mMTC) , ultra-reliable low latency communication (URLLC) , Carrier Aggregation (CA) , Dual Connection (DC) , and New Radio Unlicensed (NR-U) technologies.
In various example embodiments of the present disclosure, the secondary cells 120 are preconfigured to be potential primary cells which can be switched to be a primary cell. The network device 105 indicates to the terminal device 110 pre-configurations for the secondary cells for use when the switching is enabled. When the network device 105 decides to switch a secondary cell 120 to be a primary cell, the network device 105 transmits a switch indication to the terminal device 110. The switching is caused by the network device 105 after a confirmation is received from the terminal device 110.
FIG. 2 illustrates a signaling flow 200 between the network device 105 and the terminal device 110 in a fast primary cell change/switch in accordance with some example embodiments of the present disclosure.
As shown in FIG. 2, the network device 105 transmits (205) a set of pre-configurations to the terminal device 110 via a message (referred to as a first message) . At least one pre-configuration in the set of pre-configurations is associated with a secondary cell 120. The at least one pre-configuration can be activated when the associated secondary cell is switched as a primary cell. The at least one pre-configuration may include any suitable types of configurations for use when the associated secondary cell is switched to be a primary cell.
In some example embodiments, the pre-configuration associated with the secondary cell may be related to a system block (SIB) , a Physical Downlink Control Channel (PDCCH) , a Physical Uplink Control Channel (PUCCH) , a Physical Downlink Shared Channel (PDSCH) , a Physical Uplink Shared Channel (PUSCH) , a downlink bandwidth part (BWP) , an uplink BWP, uplink synchronization, Path Loss (PL) reference, Timing Advance (TA) and the like.
As an example, the pre-configuration may include resource allocation such as a PUCCH resource for a HARQ feedback, a Channel Quality Indicator (CQI) report or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and any other time, frequency, code and space resources. The pre-configuration may also include timers, a security key and the like for use in the associated secondary cell when the secondary cell is switched to be a primary cell.
The pre-configurations may be indicated by the network device 105 to the terminal device 110 in the primary cell 115 or the secondary cell 120. In the scenario where the terminal device 110 is served by more than one network devices, the pre-configurations may be indicated by any one or more of the serving network devices in any one or more serving cells.
The first message may be any suitable message, including, for example, a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message. As an example, in the example embodiments where the first message comprises a signaling message dedicated to the terminal device 110, the network device 105 may send the pre-configurations to the terminal device 110 in the signaling message dedicated to the terminal device 110, such as Radio Resource Control (RRC) signaling or a media access control (MAC) control element (CE) . It is also possible that as least a part of the pre-configurations are broadcast by the network device 105 in system information such as a system information block (SIB) .
If a secondary cell in the set of secondary cells is determined to be switched as a primary cell, the network device 105 transmits (210) a switch indication for the switching to the terminal device 110 via a message (referred to as a second message) separate from the first message. The primary cell switch may be triggered at the network device 105 in response to a DL LBT failure. For example, the network device 105 may select a secondary cell to be switched upon a DL LBT failure in the primary cell 115. In some example embodiments, a threshold about the number of DL LBT failures may be set to avoid excessively frequent primary cell switching. For example, when continuous LBT failures occur for N (where N represents a positive integer) times in the primary cell 115, the network device 105 may determine the switching.
The primary cell switch may also be triggered in response to a UL LBT failure. For example, the terminal device 110 may send a request for primary cell switch to change the primary cell 115 upon detection of one or more UL LBT failure. The request may be sent by the terminal device 110 through a MAC CE, for example. In response to this request, the network device 105 may trigger the switching.
Alternatively, in the case that more than one network device provides the serving cells, the primary cell switch may be triggered by a master network device providing the current primary cell. For example, in the case that the current primary cell is served by a further network device, the further network device may send an indication of a DL LBT failure in the primary cell to the network device 105 for example via a X2 interface between the two network devices to trigger the primary cell switch. Alternatively, the primary cell switch is done by the network device serving the corresponding primary cell. For example, a master node sends a switch indication for PCell, and a secondary node sends a switch indication for PSCell.
The second message may comprise any suitable message, including a MAC message and a PHY layer message, for example. In the example embodiments where the second message comprises a MAC CE, the switch indication may be sent in the MAC CE to further expedite the primary cell change. In order to ensure the transmission security of the MAC CE, authentication information may be included in the MAC CE, which may comprise Message Authentication Code-Integrity (MAC-I) or MAC-I2, for example. With the MAC-I, the terminal device 110 may check the integrity of the MAC CE to avoid network attacking.
In some other example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order which initiates a random access procedure on the secondary cell to be switched as a primary cell. Accordingly, the switch indication may be sent in the PDCCH order. For example, the PDCCH order may include a new field for carrying the switch indication. As another example, an existing field in the PDCCH order may be assigned to a new value to indicate the switching. Other implementations of using the PDCCH order to indicate the switching are possible. The scope of the present disclosure is not limited in this regard.
The switch indication may identify the secondary cell 120 to be switched in any suitable way. In some example embodiments, the MAC CE or the PDCCH order may be transmitted by the network device 105 to the terminal device 110 in the secondary cell 120 to be switched or changed. Upon the reception of the switch indication in the secondary cell 120, the terminal device 120 may determine that the secondary cell 120 is to be switched as a primary cell. That is, the secondary cell from which the switch indication is received is considered as the secondary cell to be switched implicitly.
In some other example embodiments, the MAC CE or the PDCCH order may be scheduled by the network device 105 across carriers in another secondary cell with a cell identification (such as a cell index or cell identifier) pointing to the secondary cell to be switched to be a primary cell. For example, the network device 105 may transmit the switch indication via a further secondary cell to the terminal device, the switch indication includes a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell. The cell index or cell identifier may be needed when more than one secondary cell is pre-configured as potential primary cells and it is cross-scheduled.
After transmitting (210) the switch indication, the network device 105 receives (215) a confirmation for the switching from the terminal device 110. In some example embodiments, the confirmation may be received from the terminal device 110 by using the at least one pre-configuration associated with the secondary cell to be switched or changed. For example, in the example embodiments where the switch indication is sent by the network device 105 in a MAC CE and the at least one pre-configuration comprises a PUCCH resource in the secondary cell, the terminal device 110 may transmit a HARQ feedback, such as an acknowledgement (ACK) , for the MAC CE using the PUCCH resource as the confirmation for the switching of the secondary cell. Upon reception of the HARQ feedback, the network device 105 knows that the switching is confirmed by the terminal device 120.
In the example embodiments where the at least one pre-configuration comprises a PRACH resource in the secondary cell, the terminal device 110 may send a random access request using the PRACH resource as the confirmation for the switching of the secondary cell. As such, the confirmation from the terminal device 110 may be implemented using a random access (RA) procedure performed in the secondary cell to be switched as a new primary cell. The random access request may include a random access preamble. In some example embodiments, the switch indication sent by the network device 105 may contain a dedicated preamble for the RA procedure to indicate that the terminal device 110 can use the dedicated preamble to initiate the RA procedure to confirm the primary cell switch or change. In some example embodiments, a message 3 (Msg3) in the RA procedure associated with the pre-configuration from the terminal device 110 may serve as the confirmation.
After receiving (215) the confirmation from the terminal device 110, the network device 105 causes (220) the at least one pre-configuration to be activated to switch the associated secondary cell to be the primary cell. For example, if the terminal device 110 uses a RA procedure for the confirmation, upon reception of the random access request from the terminal device 110, the switching of the secondary cell to a primary cell may be caused at the network device 105. In some example embodiments, the switching of the secondary cell to a primary cell may be caused at the network device 105 upon the completion of the RA procedure, upon reception of a Msg3 message or after a random access response is sent by the network device 105.
Some example embodiments of the present disclosure provide a control plane (CP) solution to implement the fast primary cell change.
After the fast primary cell change/switch is triggered, the network device 105 may cause a handover from the original primary cell 115 to the secondary cell 120. For example, the pre-configuration for the secondary cell 120 may comprise configurations in higher layers such as parameters in a Radio Resource Control (RRC) layer. In this case, a media access control (MAC) entity may indicate a RRC entity to perform handover and further actions with the preconfigured RRC parameters at both the terminal device 110 and the network device 105.
In some embodiments, the network device 105 may be configured to perform the primary cell switching/changing based on a predefined rule in response to receiving the confirmation from the terminal device 110. The predefined rule may indicate at least one of: swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing of an active BWP of the secondary cell if the secondary cell is already activated, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated, and switching the original primary cell to be an activated or deactivated secondary cell.
For illustration rather than limitation, in some example embodiments, the network device 105 may cause swapping of a serving cell ID (referred to as a first serving cell ID) of the original primary cell 115 and a serving cell ID (referred to as a second serving cell ID) of the secondary cell 120 to be switched as a primary cell according to the predefined rule. In the case that the network device 105 serves both the original primary cell 115 and the secondary cell 120, the network device 105 may swap the first and second cell IDs. If the secondary cell 120 is provided by a further network devices, the network device 105 may communicate with the network device to facilitate the swapping. In some cases, a PCell may be assigned to a predefined cell ID (for example, serving cell ID 0) to distinguish from PSCells and Scells. As such, the swap of the serving cell IDs for the original primary cell and the secondary cell may ensure the new primary cell with the predefined cell ID. In the scenario where a SCell is switched to a PSCell, such swap of cell IDs may or may not be performed.
In some example embodiments, the network device 105 may cause swapping of a TAG ID (referred to as a first TAG ID) for a TAG (referred to as a first TAG) of the original primary cell 115 (for example, PCell or PSCell) and a TAG ID (referred to as a second TAG ID) for a TAG (referred to as a second TAG) of the secondary cell 120 to be switched if the first and second TAGs are different. Moreover, the new primary cell changed from the secondary cell 120 may be considered as timing reference for the new primary TAG regardless of whether the secondary cell 120 was used as timing reference before the switching. Similar to the swapping of the cell IDs, the network device 105 may perform the swapping of the TAG IDs when both the original primary cell 115 and the secondary cell 120 are provided by the network device 105. The network device 105 may facilitate the swapping of the TAG IDs via communication with another network device if the secondary cell 120 is provided by that network device.
In some example embodiments, the network device 105 may cause swapping of PUCCH groups according to the predefined rule. Likewise, this swapping may be performed by the network device 105 alone or in cooperation with another network device. For example, the network device 105 may cause mapping of at least one PUCCH for at least one secondary cell within a PUCCH group to the secondary cell 120 when the secondary cell 120 becomes a new primary cell within the PUCCH group.
By way of example, if the secondary cell 120 was a PUCCH SCell before the switching, the secondary cell (s) (or Scells) whose PUCCH is mapped to the secondary cell 120 remains in the same or original PUCCH group when the secondary cell 120 becomes a new PCell. Then, the original primary cell 115 becomes a PUCCH SCell with the secondary cell (s) mapping to the primary cell 115 remains in the same or original PUCCH group. When the secondary cell 120 was not a PUCCH SCell (without PUCCH mapping from any other secondary cells) before switching, and if the secondary cell 120 is within the same PUCCH group as the original primary cell 115, the secondary cell (s) within the PUCCH group will be mapped to the new PCell and the PUCCH configuration from the original primary cell 115 is invalidated after the secondary cell 120 is switched as the new PCell. If the secondary cell 120 is within a PUCCH group with a PUCCH SCell, the secondary cell (s) whose PUCCH is mapped to the PUCCH SCell will be mapped to the new PCell and the PUCCH resource from the original PUCCH SCell is invalidated after the secondary cell 120 is switched as the new PCell. The original primary cell 115 will become a PUCCH SCell with the SCell (s) maps to it remains.
Alternatively or in addition, the further actions may be related to the DL or UL BWP. For example, if the secondary cell is already activated, the network device 105 may cause reuse of an activate BWP of the secondary cell 120, other than switch to a configured first active BWP of the secondary cell 120, by reusing the activate BWP or directing another network device to reuse the activate BWP. If the secondary cell 120 is deactivated, a first active BWP of the secondary cell 120 or an initial BWP of the secondary cell 120 (when the first active BWP is not preconfigured) may be enabled or activated. As an alternative example, the pre-configuration may indicate the terminal device 110 to always switch to the first active BWP of the secondary cell 120 if any. It may be also possible that the terminal device 110 negotiates the BWP to be used after the fast primary cell change or switch with the network device 105 in a pre-configuration phase.
In some example embodiments, the original primary cell 115 (for example, PCell or PSCell) is switched by the network device 105 to be a secondary cell with the configurations kept. As such, the network can switch back to the original primary cell 115 when desired. The secondary cell changed from the original primary cell 115 may be either active or in a deactivated state after the switching. Alternatively, the original primary cell 115 may be removed. Then, it is only needed to set the IDs such as a cell ID and a TAG ID for the secondary cell 120 to be switched to be the primary cell.
The CP model or the predefined rule may be embodied in RRC procedural text, and a new IE for pre-configuration may be embodied in RRC ASN. 1.
Accordingly, the terminal device 110 may apply the at least one pre-configuration associated with the secondary cell for communication at initiation of the RA procedure. For example, the pre-configuration related to the RA procedure (such as a resource, timers and the like) may be applied by the terminal device 110 upon the initiation of the RA procedure. It is also possible that some other pre-configurations are applied upon the initiation of the RA procedure. As another example, the terminal device 110 may apply the at least one pre-configuration associated with the secondary cell for communication after receiving a random access response from the network device 105 or upon the completion of the RA procedure or reception of Message 4 (Msg4) from the network device 105.
In addition to the activation of the pre-configuration associated with the secondary cell 120, the terminal device 110 may perform further actions for the handover from the original primary cell 115 to the secondary cell 120. In some example embodiments, upon reception of the switching indication or completion of the switching procedure (for example upon RACH completion or after the HARQ feedback such as ACK for the MAC CE is sent) , the terminal device 110 may swap the first serving cell ID of the original primary cell 115 and the second serving cell ID of the secondary cell 120. The terminal device 110 may also swap the first TAG ID for the first TAG of the original primary cell 115 and the second TAG ID for the second TAG of the secondary cell 120 if the first and second TAGs are different.
In some example embodiments, the terminal device 110 may perform the actions related to swapping of PUCCH groups, enabling or activation of the DL or UL BWP, and switching of the original primary cell as an activated or deactivated secondary cell, as described above.
For example, in the scenario where the secondary cell to be switched is served by the network device 105, the network device 105 may activate the pre-configuration associated with the secondary cell. Alternatively or in addition, in the scenario where the secondary cell to be switched is served by a further network device, the network device 105 sends an activation indication to the further network device for example via a X2 interface to cause the further network device to activate the pre-configuration associated with the secondary cell.
In some example embodiments, the at least one pre-configuration may comprise a security key preconfigured for a secondary cell 120 and enabled after the secondary cell 120 is switched to be a new primary cell in order to ensure the communication security. For example, the terminal device 110 may suspend Layer 2 (L2) reception after the PDCCH order or MAC CE, and then resumed with the new key after the RACH completion or HARQ ACK. It is also possible that the key is not changed during the switching of a secondary cell to a primary cell.
An example implementation of the fast primary cell change will be discussed below. In this example, when a RRC connection is established with the primary cell 115 (or Cell1) on the unlicensed band, the terminal device 110 reports its capability of supporting fast primary cell change to the network device 105. When a cell (or Cell2) on the unlicensed band is added as a secondary cell 120 of the terminal device 110, the pre-configuration of all necessary parameters for switching the secondary cell 120 to a primary cell (for example, PCell or PSCell) is sent to the terminal device 110 via a RRC message such as a RRCReconfiguration message from current serving cell (s) such as the primary cell 115. The terminal device 110 stores the pre-configuration of Cell2 in UE Variables, for example.
When N (N＞0) LBT failures are detected on Cell1 and Cell2 is with good quality, the network device 105 may send a UP command for the fast primary cell change such as a MAC CE or PDCCH order to the terminal device 110 via Cell2. When receiving the UP command, the terminal device 110 enables the stored pre-configuration of Cell2 to change Cell2 to be a primary cell (for example, PCell or PSCell) and change Cell1 to be a secondary cell. A RACH access to Cell2 or HARQ feedback for the downlink MAC CE may be acknowledged to the network device 105 as the confirmation to the received UP command. When receiving the confirmation from the terminal device 110, the network device 115 enables the stored pre-configuration locally to configure Cell2 to be a primary cell and Cell1 to be a secondary cell.
FIG. 3 shows a flowchart of an example method 300 according to some example embodiments of the present disclosure. The method 300 can be implemented by the network device 105 as shown in FIG. 1. For the purpose of discussion, the method 300 will be described with reference to FIG. 1.
At block 305, the network device 105 transmits a set of pre-configurations to the terminal device 110 via a first message. At least one pre-configuration in the set of pre-configurations is associated with a secondary cell in a set of secondary cells, and is activated if the associated secondary cell is switched to be a primary cell.
At block 310, the network device 105 transmits, to the terminal device 110 via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell. At block 315, in response to receiving a confirmation for the switching from the terminal device 110, the network device 105 causes the at least one pre-configuration associated with the secondary cell to be activated.
In some example embodiments, the first message comprises a signaling message dedicated to the terminal device. The network device 105 transmits the set of pre-configurations in the signaling message dedicated to the terminal device 110.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) . The network device 105 transmits the switch indication in the MAC CE. The MAC CE may include authentication information such as Message Authentication Code-Integrity (MAC-I) .
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order. The network device 105 transmits the switch indication in the PDCCH order. The PDCCH order may include a field for carrying the switch indication.
In some example embodiments, the secondary cell is served by the network device 105. In some example embodiments, the network device 105 receives the confirmation from the terminal device 110 by using the at least one pre-configuration associated with the secondary cell.
In some example embodiments, if the second message comprises a media access control (MAC) control element (CE) and the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, the network device 105 may receive a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
In some example embodiments, if the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, the network device 105 may receive a random access request as the confirmation from the terminal device in using PRACH resource. In some example embodiments, the switch indication may include a dedicated preamble for the random access request.
In some example embodiments, after receiving the random access request from the terminal device 110, the network device 105 transmits a random access response to the terminal device 110. Further, the network device 105 activates the at least one pre-configuration associated with the secondary cell. In some other example embodiments, the network device 105 may activate the at least one pre-configuration associated with the secondary cell upon completion of a random access procedure initiated by the terminal device 110 using the random access request.
In some example embodiments, the network device 105 may transmit the switch indication via the second message in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the network device 105 may select the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device 110.
In some example embodiments, a further secondary cell in the set of the secondary cells is served by the network device 105. In these embodiments, the network device 105 may transmit the switch indication via the second message in the further secondary cell to the terminal device 110, and the switch indication includes a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the secondary cell is served by a further network device. In these embodiments, the network device 105 may send an activation indication to the further network device to activate the at least one pre-configuration associated with the secondary cell.
In some example embodiments, the at least one pre-configuration comprises configurations necessary for a cell to serve as a primary cell. As an example, the at least one pre-configuration may comprise at least one of a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback, a Channel Quality indicator (CQI) report or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the first message may comprise one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message may comprise one of a MAC message and a PHY layer message.
In some example embodiments, the network device 105 may perform the switching based on a predefined rule in response to receiving the confirmation. The predefined rule may indicate at least one of: swapping of the first serving cell identity for the original primary cell 115 and the second serving cell identity for the secondary cell 110, swapping of the first TAG ID for the first TAG of the original primary cell 115 and the second TAG ID for the second TAG of the secondary cell 120 if the first TAG is different from the second TAG, mapping of at least one PUCCH for at least one secondary cell within a PUCCH group to the secondary cell 120 when the secondary cell 120 becomes a new primary cell within the PUCCH group, reusing of an active BWP of the secondary cell 120 if the secondary cell 120 is already activated, and activation of a first active BWP or an initial BWP of the secondary cell 120 if the secondary cell 120 is deactivated, and switching the original primary cell 115 to be an activated or deactivated secondary cell.
FIG. 4 shows a flowchart of an example method 400 according to some example embodiments of the present disclosure. The method 400 can be implemented by the terminal device 110 as shown in FIG. 1. For the purpose of discussion, the method 400 will be described with reference to FIG. 1.
At block 405, the terminal device 110 receives a set of pre-configurations from the network device 105 via a first message. At least one pre-configuration in the set of pre-configurations is associated with a secondary cell in a set of secondary cells and is activated if the associated secondary cell is switched to be a primary cell.
At block 410, the terminal device 110 receives, from the network device 105 via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell. At block 415, the terminal device 110 transmits a confirmation for the switching to the network device 105.
In some example embodiments, the terminal device 110 may receive a random access response from the network device. Then, the terminal device 110 may apply the at least one pre-configuration associated with the secondary cell for communication. In some example embodiments, the terminal device 110 may apply the at least one pre-configuration associated with the secondary cell for communication upon completion of a random access procedure initiated using the random access request. In some other example embodiments, the terminal device 110 may apply the at least one pre-configuration associated with the secondary cell for communication upon initiation of the random access procedure.
In some example embodiments, in response to an uplink LBT failure in a current primary cell, the terminal device 110 may transmit a request for primary cell switch to the network device.
In some example embodiments, the terminal device 110 may perform the switching based on a predefined rule. The predefined rule may indicate at least one of: swapping the first serving cell identity for the original primary cell 115 and the second serving cell identity for the secondary cell 110, swapping the first TAG ID for the first TAG of the original primary cell 115 and the second TAG ID for the second TAG of the secondary cell 120 if the first TAG is different from the second TAG, mapping of at least one PUCCH for at least one secondary cell within a PUCCH group to the secondary cell 120 when the secondary cell 120 becomes a new primary cell within the PUCCH group, reusing an active BWP of the secondary cell 120 if the secondary cell 120 is already activated, and switching to a first active BWP or an initial BWP of the secondary cell 120 if the secondary cell 120 is deactivated, and switching the original primary cell 115 to be an activated or deactivated secondary cell.
All operations and features as described above with reference to FIGS. 1 and 2 are likewise applicable to the methods 300 and 400 and have similar effects. For the purpose of simplification, the details will be omitted.
In some example embodiments, the methods 300 and 400 described above with reference to FIGS. 1-4 may be performed by an apparatus comprising means for performing the respective steps of the methods 300 and 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.
FIG. 5 is a simplified block diagram of a device 500 that is suitable for implementing example embodiments of the present disclosure. The device 500 can be implemented at or as a part of the network device 105 or the terminal device 110 as shown in FIG. 1.
As shown, the device 500 includes a processor 510, a memory 520 coupled to the processor 510, a communication module 530 coupled to the processor 510, and a communication interface (not shown) coupled to the communication module 530. The memory 520 stores at least a program 540. The communication module 530 is for bidirectional communications, for example, via multiple antennas. The communication interface may represent any interface that is necessary for communication.
The program 540 is assumed to include program instructions that, when executed by the associated processor 510, enable the device 500 to operate in accordance with the example embodiments of the present disclosure, as discussed herein with reference to FIGS. 1-4. The example embodiments herein may be implemented by computer software executable by the processor 510 of the device 500, or by hardware, or by a combination of software and hardware. The processor 510 may be configured to implement various example embodiments of the present disclosure.
The memory 520 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 520 is shown in the device 500, there may be several physically distinct memory modules in the device 500. The processor 510 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.
When the device 500 acts as the network device 105 or a part of the network device 105, the processor 510 and the communication module 530 may cooperate to implement the method 300 as described above with reference to FIG. 3. When the device 500 acts as the terminal device 110 or a part of the terminal device 110, the processor 510 and the communication module 530 may cooperate to implement the method 400 as described above with reference to FIG. 4.
All operations and features as described above with reference to FIGS. 1-4 are likewise applicable to the device 500 and have similar effects. For the purpose of simplification, the details will be omitted.
Generally, various example embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of example embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods 300 and 400 as described above with reference to FIGS. 1-4. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various example embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.
Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.
In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, a computer readable medium and the like.
The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , Digital Versatile Disc (DVD) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular example embodiments. Certain features that are described in the context of separate example embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple example embodiments separately or in any suitable sub-combination.
Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
Various example embodiments of the techniques have been described. In addition to or as an alternative to the above, the following examples are described. The features described in any of the following examples may be utilized with any of the other examples described herein.
In some aspects, a device comprises: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the device to: transmit a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; transmit, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and in response to receiving a confirmation for the switching from the terminal device, cause the at least one pre-configuration associated with the secondary cell to be activated.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the secondary cell is served by the device, and the device is caused to transmit the switch indication by: transmitting, to the terminal device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the device is caused to receive the confirmation by: receiving a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the device is caused to receive the confirmation by: receiving a random access request as the confirmation from the terminal device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and the device causes the at least one pre-configuration associated with the secondary cell to be activated by: in response to receiving the random access request, transmitting a random access response to the terminal device; and activating the at least one pre-configuration associated with the secondary cell upon at least one of: the transmission of the random access response, and completion of a random access procedure initiated by the terminal device using the random access request.
In some example embodiments, the device is further caused to: select the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device.
In some example embodiments, a further secondary cell in the set of the secondary cells is served by the device, and the device is caused to transmit the switch indication by: transmitting, to the terminal device via the second message in the further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the secondary cell is served by a further device, and the device causes the at least one pre-configuration associated with the secondary cell to be activated by: sending an activation indication to the further device to activate the at least one pre-configuration associated with the secondary cell.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the device is further caused to perform the switching based on a predefined rule in response to receiving the confirmation, wherein the predefined rule indicates at least one of: swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing of an active BWP of the secondary cell if the secondary cell is already activated before the switching, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, a device comprises: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the device to: receive a set of pre-configurations from a network device via a first message, at least one pre-configuration in the set of at least one pre-configuration being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; receive, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and transmit a confirmation for the switching to the network device.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the device is caused to transmit the confirmation by: transmitting a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation to the network device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the device is caused to transmit the confirmation by: transmitting a random access request as the confirmation to the network device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and the device is further caused to: apply the at least one pre-configuration associated with the secondary cell for communication upon at least one of: initiation of a random access procedure using the random access request, reception of a random access response from the network device, and completion of a random access procedure initiated using the random access request.
In some example embodiments, the device is caused to receive the switch indication by: receiving, from the network device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the device is caused to receive the switch indication by: receiving, from the network device via the second message in a further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the device is further caused to: in response to an uplink LBT failure in a current primary cell, transmitting a request for primary cell switch to the network device.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the device is further caused to perform the switching based on a predefined rule, wherein the predefined rule indicates at least one of: swapping a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of a least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing an active BWP of the secondary cell if the secondary cell is already activated before the switching, and switching to a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, a method comprises: transmitting, at a network device, a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; transmitting, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and in response to receiving a confirmation for the switching from the terminal device, causing the at least one pre-configuration associated with the secondary cell to be activated.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the secondary cell is served by the device, and transmitting the switch indication comprises: transmitting, to the terminal device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and receiving the confirmation comprises: receiving a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and receiving the confirmation comprises: receiving a random access request as the confirmation from the terminal device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and causing the at least one pre-configuration associated with the secondary cell to be activated comprises: in response to receiving the random access request, transmitting a random access response to the terminal device; and activating the at least one pre-configuration associated with the secondary cell upon at least one of: the transmission of the random access response, and completion of a random access procedure initiated by the terminal device using the random access request.
In some example embodiments, the method further comprises: selecting the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device.
In some example embodiments, a further secondary cell in the set of the secondary cells is served by the device, and transmitting the switch indication comprises: transmitting, to the terminal device in the further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the secondary cell is served by a further network device, and causing the at least one pre-configuration associated with the secondary cell to be activated comprises: sending an activation indication to the further network device to activate the at least one pre-configuration associated with the secondary cell.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the method further comprises performing the switching based on a predefined rule in response to receiving the confirmation, wherein the predefined rule indicates at least one of: swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of a least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing of an active BWP of the secondary cell if the secondary cell is already activated before the switching, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, a method comprises: receiving, at a terminal device, a set of pre-configurations from a network device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; receiving, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and transmitting a confirmation for the switching to the network device.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and transmitting the confirmation comprises: transmitting a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation to the network device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and transmitting the confirmation comprises: transmitting a random access request as the confirmation to the network device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and the method further comprises: applying the at least one pre-configuration associated with the secondary cell for communication upon at least one of: initiation of a random access procedure using the random access request, reception of a random access response from the network device, and completion of a random access procedure initiated using the random access request.
In some example embodiments, receiving the switch indication comprises: receiving, from the network device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, receiving the switch indication comprises: receiving, from the network device via the second message in a further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the method further comprises: in response to an uplink LBT failure in a current primary cell, transmitting a request for primary cell switch to the network device.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the method further comprises performing the switching based on a predefined rule, wherein the predefined rule indicates at least one of: swapping a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing an active BWP of the secondary cell if the secondary cell is already activated before the switching, and switching to a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, an apparatus comprises: means for transmitting, at a network device, a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; means for transmitting, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and means for in response to receiving a confirmation for the switching from the terminal device, causing the at least one pre-configuration associated with the secondary cell to be activated.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the secondary cell is served by the device, and the means for transmitting the switch indication comprises: means for transmitting, to the terminal device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the means for receiving the confirmation comprises: means for receiving a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the means for receiving the confirmation comprises: means for receiving a random access request as the confirmation from the terminal device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and the means for causing the at least one pre-configuration associated with the secondary cell to be activated comprises: means for in response to receiving the random access request, transmitting a random access response to the terminal device; and activating the at least one pre-configuration associated with the secondary cell upon at least one of: the transmission of the random access response, and completion of a random access procedure initiated by the terminal device using the random access request.
In some example embodiments, the apparatus further comprises: means for selecting the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device.
In some example embodiments, a further secondary cell in the set of the secondary cells is served by the device, and the means for transmitting the switch indication comprises: means for transmitting, to the terminal device via the second message in the further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the secondary cell is served by a further network device, and the means for causing the at least one pre-configuration associated with the secondary cell to be activated comprises: means for sending an activation indication to the further network device to activate the at least one pre-configuration associated with the secondary cell.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the apparatus further comprises means for performing the switching based on a predefined rule in response to receiving the confirmation, wherein the predefined rule indicates at least one of: swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of a least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing of an active BWP of the secondary cell if the secondary cell is already activated before the switching, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, an apparatus comprises: means for receiving, at a terminal device, a set of pre-configurations from a network device via a separate second message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell; means for receiving, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and means for transmitting a confirmation for the switching to the network device.
In some example embodiments, the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
In some example embodiments, the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
In some example embodiments, the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the means for transmitting the confirmation comprises: means for transmitting a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation to the network device using the PUCCH resource.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the means for transmitting the confirmation comprises: transmitting a random access request as the confirmation to the network device using the PRACH resource.
In some example embodiments, the switch indication includes a dedicated preamble for the random access request, and the apparatus further comprises: means for applying the at least one pre-configuration associated with the secondary cell for communication upon at least one of: initiation of a random access procedure using the random access request, reception of a random access response from the network device, and completion of a random access procedure initiated using the random access request.
In some example embodiments, the means for receiving, from the network device via the second message, the switch indication comprises: means for receiving the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
In some example embodiments, the means for receiving the switch indication comprises: means for receiving, from the network device via the second message in a further secondary cell, the switch indication including a cell identification for the secondary cell as to switch the secondary cell indicated by the cell identification to be the primary cell.
In some example embodiments, the apparatus further comprises: means for in response to an uplink LBT failure in a current primary cell, transmitting a request for primary cell switch to the network device.
In some example embodiments, the at least one pre-configuration associated with the secondary cell comprises at least one of: a security key for communication in the secondary cell, a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) , a Physical Random Access Channel (PRACH) resource, a common search space (CSS) , and at least one timer.
In some example embodiments, the apparatus further comprises means for performing the switching based on a predefined rule, wherein the predefined rule indicates at least one of: swapping a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell, swapping a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG, mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group, reusing an active BWP of the secondary cell if the secondary cell is already activated before the switching, and switching to a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and switching the original primary cell to be an activated or deactivated secondary cell.
In some aspects, a computer readable storage medium comprises program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method according to some example embodiments of the present disclosure.

Claims

A device comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the device to:

transmit a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

transmit, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

in response to receiving a confirmation for the switching from the terminal device, cause the at least one pre-configuration associated with the secondary cell to be activated.
The device of claim 1, wherein the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
The device of claim 1, wherein the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
The device of claim 1, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) order, the PDCCH order includes a field for carrying the switch indication.
The device of claim 1, wherein the secondary cell is served by the device, and the device is caused to transmit the switch indication by:

transmitting, to the terminal device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
The device of claim 5, wherein the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the device is caused to receive the confirmation by:

receiving a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
The device of claim 5, wherein the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the device is caused to receive the confirmation by:

receiving a random access request as the confirmation from the terminal device using the PRACH resource.
The device of claim 7, wherein the switch indication includes a dedicated preamble for the random access request, and the device causes the at least one pre-configuration associated with the secondary cell to be activated by:

in response to receiving the random access request, transmitting a random access response to the terminal device; and

activating the at least one pre-configuration associated with the secondary cell upon at least one of:

the transmission of the random access response, and

completion of a random access procedure initiated by the terminal device using the random access request.
The device of claim 5, wherein the device is further caused to:

select the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device.
The device of claim 1, wherein a further secondary cell in the set of the secondary cells is served by the device, and the device is caused to transmit the switch indication by:

transmitting, to the terminal device via the second message in the further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
The device of claim 1, wherein the secondary cell is served by a further device, and the device causes the at least one pre-configuration associated with the secondary cell to be activated by:

sending an activation indication to the further device to activate the at least one pre-configuration associated with the secondary cell.
The device of claim 1, wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communication in the secondary cell,

a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) ,

a Physical Random Access Channel (PRACH) resource,

a common search space (CSS) , and

at least one timer.
The device of claim 1, wherein the device is further caused to perform the switching based on a predefined rule in response to receiving the confirmation, wherein the predefined rule indicates at least one of:

swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell,

swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG,

mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group,

reusing of an active BWP of the secondary cell if the secondary cell is already activated before the switching, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and

switching the original primary cell to be an activated or deactivated secondary cell.
A device comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the device to:

receive a set of pre-configurations from a network device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

receive, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

transmit a confirmation for the switching to the network device.
The device of claim 14, wherein the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
The device of claim 14, wherein the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
The device of claim 14, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
The device of claim 14, wherein the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and the device is caused to transmit the confirmation by:

transmitting a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation to the network device using the PUCCH resource.
The device of claim 14, wherein the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and the device is caused to transmit the confirmation by:

transmitting a random access request as the confirmation to the network device using the PRACH resource.
The device of claim 19, wherein the switch indication includes a dedicated preamble for the random access request, and the device is further caused to:

apply the at least one pre-configuration associated with the secondary cell for communication upon at least one of:

initiation of a random access procedure using the random access request,

reception of a random access response from the network device, and

completion of a random access procedure initiated using the random access request.
The device of claim 14, wherein the device is caused to receive the switch indication by:

receiving, from the network device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
The device of claim 14, wherein the device is caused to receive the switch indication by:

receiving, from the network device via the second message in a further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
The device of claim 14, wherein the device is further caused to:

in response to an uplink LBT failure in a current primary cell, transmitting a request for primary cell switch to the network device.
The device of claim 14, wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communication in the secondary cell,

a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) ,

a Physical Random Access Channel (PRACH) resource,

a common search space (CSS) , and

at least one timer.
The device of claim 14, wherein the device is further caused to performthe switching based on a predefined rule, wherein the predefined rule indicates at least one of:

swapping a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell,

swapping a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG,

mapping of a least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group,

reusing an active BWP of the secondary cell if the secondary cell is already activated before the switching, and switching to a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and

switching the original primary cell to be an activated or deactivated secondary cell.
A method comprising:

transmitting, at a network device, a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

transmitting, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

in response to receiving a confirmation for the switching from the terminal device, causing the at least one pre-configuration associated with the secondary cell to be activated.
The method of claim 26, wherein the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
The method of claim 26, wherein the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
The method of claim 26, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
The method of claim 26, wherein the secondary cell is served by the device, and transmitting the switch indication comprises:

transmitting, to the terminal device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
The method of claim 30, wherein the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and receiving the confirmation comprises:

receiving a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation from the terminal device using the PUCCH resource.
The method of claim 30, wherein the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and receiving the confirmation comprises:

receiving a random access request as the confirmation from the terminal device using the PRACH resource.
The method of claim 32, wherein the switch indication includes a dedicated preamble for the random access request, and causing the at least one pre-configuration associated with the secondary cell to be activated comprises:

in response to receiving the random access request, transmitting a random access response to the terminal device; and

activating the at least one pre-configuration associated with the secondary cell upon at least one of:

the transmission of the random access response, and

completion of a random access procedure initiated by the terminal device using the random access request.
The method of claim 30, further comprising:

selecting the secondary cell from the set of secondary cells to be switched to be the primary cell in response to at least one of a downlink listen before talk (LBT) failure in a current primary cell and a request for primary cell switch from the terminal device.
The method of claim 26, wherein a further secondary cell in the set of the secondary cells is served by the device, and transmitting the switch indication comprises:

transmitting, to the terminal device via the second message in the further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
The method of claim 26, wherein the secondary cell is served by a further network device, and causing the at least one pre-configuration associated with the secondary cell to be activated comprises:

sending an activation indication to the further network device to activate the at least one pre-configuration associated with the secondary cell.
The method of claim 26, wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communication in the secondary cell,

a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) ,

a Physical Random Access Channel (PRACH) resource,

a common search space (CSS) , and

at least one timer.
The method of claim 26, further comprising performing the switching based on a predefined rule in response to receiving the confirmation, wherein the predefined rule indicates at least one of:

swapping of a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell,

swapping of a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG,

mapping of a least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group,

reusing of an active BWP of the secondary cell if the secondary cell is already activated before the switching, and activation of a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and

switching the original primary cell to be an activated or deactivated secondary cell.
A method comprising:

receiving, at a terminal device, a set of pre-configurations from a network device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

receiving, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

transmitting a confirmation for the switching to the network device.
The method of claim 39, wherein the first message comprises one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message and a Physical (PHY) layer message, and the second message comprises one of a MAC message and a PHY layer message.
The method of claim 39, wherein the second message comprises a media access control (MAC) control element (CE) , and the MAC CE includes Message Authentication Code-Integrity (MAC-I) as authentication information.
The method of claim 39, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) order, and the PDCCH order includes a field for carrying the switch indication.
The method of claim 39, wherein the second message comprises a media access control (MAC) control element (CE) , the at least one pre-configuration associated with the secondary cell comprises a Physical Uplink Control Channel (PUCCH) resource in the secondary cell, and transmitting the confirmation comprises:

transmitting a hybrid automatic repeat request (HARQ) feedback for the MAC CE as the confirmation to the network device using the PUCCH resource.
The method of claim 39, wherein the at least one pre-configuration associated with the secondary cell comprises a Physical Random Access Channel (PRACH) resource in the secondary cell, and transmitting the confirmation comprises:

transmitting a random access request as the confirmation to the network device using the PRACH resource.
The method of claim 44, wherein the switch indication includes a dedicated preamble for the random access request, and the method further comprises:

applying the at least one pre-configuration associated with the secondary cell for communication upon at least one of:

initiation of a random access procedure using the random access request,

reception of a random access response from the network device, and

completion of a random access procedure initiated using the random access request.
The method of claim 39, wherein receiving the switch indication comprises:

receiving, from the network device via the second message, the switch indication in the secondary cell to indicate that the secondary cell is to be switched to be a primary cell.
The method of claim 39, wherein receiving the switch indication comprises:

receiving, from the network device via the second message in a further secondary cell, the switch indication including a cell identification for the secondary cell to switch the secondary cell indicated by the cell identification to be the primary cell.
The method of claim 39, further comprising:

in response to an uplink LBT failure in a current primary cell, transmitting a request for primary cell switch to the network device.
The method of claim 39, wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communication in the secondary cell,

a Physical Uplink Control Channel (PUCCH) resource for a hybrid automatic repeat request (HARQ) feedback or a scheduling request (SR) ,

a Physical Random Access Channel (PRACH) resource,

a common search space (CSS) , and

at least one timer.
The device of claim 39, further comprising performing the switching based on a predefined rule, wherein the predefined rule indicates at least one of:

swapping a first serving cell identity for an original primary cell and a second serving cell identity for the secondary cell,

swapping a first Timing Advance Group (TAG) identity for a first TAG of the original primary cell and a second TAG identity for a second TAG of the secondary cell if the first TAG is different from the second TAG,

mapping of at least one Physical Uplink Control Channel (PUCCH) for at least one secondary cell within a PUCCH group to the secondary cell when the secondary cell becomes a new primary cell within the PUCCH group,

reusing an active BWP of the secondary cell if the secondary cell is already activated before the switching, and switching to a first active BWP or an initial BWP of the secondary cell if the secondary cell is deactivated before the switching, and

switching the original primary cell to be an activated or deactivated secondary cell.
An apparatus comprising:

means for transmitting, at a network device, a set of pre-configurations to a terminal device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

means for transmitting, to the terminal device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

means for in response to receiving a confirmation for the switching from the terminal device, causing the at least one pre-configuration associated with the secondary cell to be activated.
An apparatus comprising:

means for receiving, at a terminal device, a set of pre-configurations from a network device via a first message, at least one pre-configuration in the set of pre-configurations being associated with a secondary cell in a set of secondary cells and being activated if the associated secondary cell is switched to be a primary cell;

means for receiving, from the network device via a separate second message, a switch indication for switching a secondary cell in the set of secondary cells to be a primary cell; and

means for transmitting a confirmation for the switching to the network device.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 26-38.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 39-50.