CN113455049B - Primary cell change - Google Patents

Abstract

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

Description

Primary cell change

Technical Field

Embodiments of the present invention relate to the field of communications, and in particular, to an apparatus, method, device, and computer-readable storage medium for primary cell change.

Background

In many scenarios, such as Carrier Aggregation (CA), dual Connectivity (DC), independent (SA) NR unlicensed (NR-U), and independent NR, unlicensed spectrum is approved for fifth generation (5G) New Radios (NRs). For example, the NR may operate in the unlicensed spectrum as a secondary cell in CA (e.g., SCell), a primary secondary cell in DC (e.g., PSCell), and a primary cell in a standalone deployment (e.g., PCell).

For channel access in unlicensed spectrum, an LTE Licensed Assisted Access (LAA) Listen Before Talk (LBT) mechanism is employed as a baseline for the 5GHz band and as a design origin for the 6GHz band. At least for a frequency band (e.g., below 7 GHz) in which NR-U is operating and where Wi-Fi is not guaranteed (e.g., by regulations), LBT may be performed in units of 20MHz if the baseline assumes that the NR-U operating bandwidth is an integer multiple of 20 MHz.

In general, hybrid automatic repeat request (HARQ) feedback for the Physical Downlink Shared Channel (PDSCH) of the SCell needs to be transmitted on the Physical Uplink Control Channel (PUCCH) in the PCell or PSCell (if not mapped to PUCCH SCell). Therefore, LBT failure in the PCell may block HARQ feedback of the SCell and thus affect throughput even though the SCell is not overloaded.

Disclosure of Invention

In general, example embodiments of the present disclosure provide apparatus, methods, apparatuses, and computer-readable storage medium for primary cell change.

In a first aspect, an apparatus is provided that includes 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 apparatus to send a set of pre-configurations to the terminal device via a first message. At least one of the set of pre-configurations is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell. The device is further caused to send a switching indication to the terminal device for switching the secondary cells of the group of secondary cells to the primary cell via a separate second message. The device is caused to cause at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device.

In a second aspect, an apparatus is provided that includes 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 apparatus to receive a set of pre-configurations from a network device via a first message. At least one of the set of pre-configurations is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell. The device is further caused to receive, via a separate second message, a switching indication from the network device to switch a secondary cell of the set of secondary cells to the primary cell, and to send an acknowledgement for the switching to the network device.

In a third aspect, a method is provided. In the method, the network device sends a set of pre-configurations to the terminal device via a first message. At least one of the set of at least one pre-configuration is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell. The network device sends a switching indication for switching the secondary cell of the group of secondary cells to the primary cell to the terminal device via a separate second message. In response to receiving an acknowledgement for the exchange from the terminal device, the network device causes 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 of the set of at least one pre-configuration is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell. The terminal device receives a switching indication from the network device for switching the secondary cells of the group of secondary cells to the primary cell via a separate second message and sends an acknowledgement 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, a computer readable storage medium comprising program instructions stored thereon is provided. 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 should be understood that the summary is not intended to identify key or essential features of the example embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

Some example embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example scenario in which some example embodiments of the present disclosure may be implemented;

fig. 2 illustrates signaling flows between a network device and a terminal device for primary cell switching 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 shows a simplified block diagram of a device suitable for implementing example embodiments of the present disclosure.

The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements.

Detailed Description

Principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that these example embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and practicing the present disclosure without placing any limitation on the scope of the present disclosure. The disclosure described herein may be implemented in various other ways besides those 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 skill 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 communication with each other or with a base station. Communication may involve the transmission and/or reception of wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for conveying information over the air. In some example embodiments, the UE may be configured to send and/or receive information without direct human interaction. For example, the UE may send information to the network device according to a predetermined schedule when triggered by an internal or external event, or in response to a request from the network side.

Examples of UEs include, but are not limited to, user Equipment (UE) (such as a smart phone), wireless-enabled tablet computer, laptop Embedded Equipment (LEE), laptop Mounted Equipment (LME), wireless Customer Premises Equipment (CPE), sensors, metering devices, personal wearable devices (such as watches, etc.), and/or communication-capable vehicles. For purposes of discussion, some example embodiments will be described with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably in the context of this disclosure.

As used herein, the term "network device" refers to a device via which services can be provided to terminal devices in a communication network. The network devices may include access network devices and core network devices. An access network device may comprise any suitable device via which a terminal device or UE may access a communication network. Examples of access network devices include relays, access Points (APs), transmission points (TRPs), node bs (nodebs or NB), evolved node bs (eNodeB or eNB), new Radio (NR) nodebs (gNB), remote radio modules (RRU), radio Heads (RH), remote Radio Heads (RRH), low power nodes (such as femto, pico), etc.

The core network device may comprise any suitable device capable of communicating with the access network device and providing services to terminal devices in the core network. Examples of core network devices may include Mobile Switching Centers (MSCs), MMEs, operations and management (O & M) nodes, operations Support System (OSS) nodes, self-organizing network (SON) nodes, positioning nodes, such as enhanced mobile services positioning centers (E-SMLCs), mobile Data Terminals (MDTs), common Control Network Functions (CCNF), access and mobility management functions (AMFs), and/or Network Slice Selection Functions (NSSF).

As used herein, the term "primary cell" or "master cell" refers to a cell of a plurality of serving cells of a terminal device that operates on a primary carrier and supports cell configuration, cell activation, and cell setup of the terminal device. In the context of the present disclosure, a primary cell may include a PCell in a Master Cell Group (MCG) or a PSCell in a Secondary Cell Group (SCG). For purposes 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 in the serving cell of the terminal device that operates on a secondary carrier and that assists the primary cell in providing additional services to the terminal device. The secondary cell may include an SCell.

As used herein, the term "circuitry" may refer to one or more or all of the following:

(a) Pure hardware circuit implementations (such as implementations in analog and/or digital circuitry only); and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combination of analog and/or digital hardware circuitry and software/firmware, and

(ii) A hardware processor (including a digital signal processor) having software, any portion of the software and memory that work in conjunction to cause a device such as a mobile phone or server to perform various functions; and

(c) Hardware circuitry and/or a processor, such as a microprocessor or a portion of a microprocessor, that requires software (e.g., firmware) to operate (but may not exist when software operation is not required).

This definition of "circuitry" applies to all uses of this term in this disclosure, including in any claims. As another example, as used in this disclosure, the term "circuitry" also encompasses an implementation of a pure hardware circuit or processor (or processors) or a hardware circuit or processor and portions of its (or their) accompanying software and/or firmware. The term "circuitry" also encompasses, 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, 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 "comprising" and variants thereof should be understood as open-ended terms, meaning "including, but not limited to. The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood 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, which should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed 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.

Unlicensed spectrum may be applied in many scenarios for 5G NR. For example, the following scenarios are contemplated:

scene a: carrier Aggregation (CA) between licensed bands NR (primary cell or PCell) and NR-U (secondary cell or SCell).

The o NR-U SCell may have both Downlink (DL) and Uplink (UL), or DL only.

In this scenario, the NR PCell is connected to a 5G core network (5G-CN).

Scene B: dual Connectivity (DC) between licensed band Long Term Evolution (LTE) (PCell) and NR-U (PScell)

In this scenario, LTE PCell connected to Evolved Packet Core (EPC) has higher priority than PCell connected to 5G-CN.

Scene C: independent (SA) NR-U

In this scenario, NR-U is connected to 5G-CN.

Scene D: independent NR cells in unlicensed band and UL in licensed band (single cell architecture)

In this scenario, NR-U is connected to 5G-CN.

Scene E: dual connectivity between licensed bands NR and NR-U

In this scenario, PCell is connected to 5G-CN, which may be handled with lower priority.

Thus, NR may be allowed to operate in unlicensed spectrum, e.g., using licensed band NR carrier(s) in CA, LTE in DC or NR in licensed band, DL and UL in unlicensed band in Standalone (SA), DL in unlicensed band in SA and UL in licensed band.

If regulations cannot guarantee that Wi-Fi is not present, for example, in the frequency band in which NR-U operates (below 7 GHz), then the baseline assumption is that NR-U operating bandwidth is an integer multiple of 20 MHz. For wideband operation of DL and UL, multiple serving cells may support bandwidths greater than 20 MHz. The NR-U should support that the serving cell can be configured with bandwidths greater than 20 MHz.

As described above, the SA and DC scenarios agreed in NR-U support CA of PCell (in unlicensed band) +scells (in unlicensed band) and CA of PSCell (in unlicensed band) +scells (in unlicensed band). In general, HARQ feedback of PDSCH of SCell needs to be transmitted on PUCCH in PCell or PSCell (if not mapped to PUCCH SCell). However, the load on the different carriers may be different, and LBT may not always succeed on the unlicensed carrier of the PCell or PSCell and the configured unlicensed carrier or carriers of the SCell. In this case, LBT failure in the PCell may block HARQ feedback of the SCell and thus affect throughput even though the SCell is not overloaded.

The conventional approach is to perform a Handover (HO) via Radio Resource Control (RRC) reconfiguration using synchronization (sync) to change one available SCell to a PCell or PSCell. For example, when the original PCell fails, the UE may perform RRC connection re-establishment to select one SCell as the PCell. Such conditional HO from PCell to Scell is performed by the UE when a certain condition is met without an indication from the network side. However, such HO procedures are slow and thus may not meet performance requirements, especially in NR-U systems. In NR-U, the time to occupy an unlicensed carrier after LBT is successful is subject to regulatory restrictions. The inventors have noted that when the SCell is not overloaded and the PCell is no longer available, it may be desirable to minimize the break time of the SCell.

Example embodiments of the present disclosure provide for fast primary cell (e.g., PCell or PSCell) change or exchange in, for example, NR-U CA and Dual Connectivity (DC). According to an example embodiment of the present disclosure, a set of secondary cells is preconfigured as potential primary cells with the necessary preconfiguration that may be used when the secondary cells are swapped with the primary cells. The network device indicates to the terminal device the pre-configuration of the secondary cell (such as resources, timers, security keys, etc.). In this way, the pre-configuration may be stored at both the network device and the terminal device and activated when a fast primary cell change is implemented.

When it is determined that a secondary cell of the secondary cells is to be switched to the primary cell, the network device sends a switching indication to the terminal device. If the network device receives an acknowledgement for the exchange from the terminal device, the network device may cause at least one pre-configuration associated with the secondary cell to be activated to exchange the secondary cell for the primary cell.

Fast primary cell change or exchange may be implemented via a downlink User Plane (UP) command such as a Medium Access Control (MAC) Control Element (CE) or a Physical Downlink Control Channel (PDCCH) command.

In this way, when consecutive LBT failures occur on a primary cell (e.g., PCell or PSCell), a secondary cell (e.g., SCell) may be swapped for the primary cell. Thus, it is avoided that the PCell or PSCell is not available for a long time due to LBT failure, which may result in the available SCell not being operable due to lack of UL resources for HARQ feedback. Furthermore, compared to the HO procedure via RRC signaling, the transmission delay can be reduced without User Plane (UP) interruption.

The fast primary cell change/exchange according to example embodiments of the present disclosure relates to both unlicensed and licensed bands for DC and CA for low latency and fast recovery targets, as follows:

Efficient and low latency serving cell configuration, activation and establishment: minimizing signaling overhead and delay required for initial cell set-up, additional cell set-up, and additional cell activation for data transmission

This objective is applicable to multiple radio access technology (Multi-RAT) DC (MR-DC), NR-NR DC and CA.

The goal should consider enhancements when starting from "idle", "inactive" and "connected" modes.

Fast recovery: supporting fast recovery of Master Cell Group (MCG) links, e.g., recovery during MCG failure by using Secondary Cell Group (SCG) links and split Signaling Radio Bearers (SRBs) while operating under MR-DC

This objective is applicable to MR-DC and NR-NR DC.

FIG. 1 illustrates an example environment 100 in which example embodiments of the present disclosure may be implemented. Environment 100, which may be part of a communication network, includes a network device 105 and a terminal device 110. It should be understood that one network device and one terminal device are shown in environment 100 for illustrative purposes only and are not intended to suggest any limitation as to the scope of the disclosure. Any suitable number of network devices and terminal devices may be included in environment 100.

The network device 105 may provide one primary cell 115 and two secondary cells 120-1 and 120-2 (collectively or individually referred to as secondary cells 120) as serving cells for the terminal device 110. The primary cell 115 and the secondary cell 120 operate on different carriers.

It should be understood that the two secondary cells 120 are shown for illustration purposes only and are not meant to be limiting. The serving cell of terminal device 110 may include any suitable number of secondary cells. It should also be understood that the serving cell is served by one network device or provided for illustration purposes only and not to be construed as limiting. The serving cell may be served by any suitable number of network devices. For example, the primary cell 115 may be served by a network device, while the secondary cell 120 may be served by one or more additional network devices. As another example, the primary cell 115 and one secondary cell 120-1 are served by one network device, while the other secondary cell 120-2 is served by another network device.

Terminal device 110 may communicate with network device 105 or with another terminal device (not shown), either directly or via network device 105. The communication may conform to any suitable communication standard or protocol, such as Universal Mobile Telecommunications System (UMTS), long Term Evolution (LTE), LTE-advanced (LTE-a), fifth generation (5G) NR, wireless fidelity (Wi-Fi), and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employ any suitable communication technology 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), mass machine type communication (mMTC), ultra-reliable low latency communication (URLLC), carrier Aggregation (CA), dual Connectivity (DC), new radio unlicensed (NR-U) technologies.

In various example embodiments of the present disclosure, the secondary cell 120 is preconfigured as a potential primary cell that can be swapped for the primary cell. The network device 105 indicates to the terminal device 110 the pre-configuration of the secondary cell to use when the exchange is enabled. When the network device 105 decides to switch the secondary cell 120 to the primary cell, the network device 105 sends a switch indication to the terminal device 110. The exchange is caused by the network device 105 after receiving an acknowledgement from the terminal device 110.

Fig. 2 illustrates a signaling flow 200 between a network device 105 and a terminal device 110 in a fast primary cell change/exchange according to some example embodiments of the present disclosure.

As shown in fig. 2, the network device 105 sends (205) a set of pre-configurations to the terminal device 110 via a message, referred to as a first message. At least one of the set of presets is associated with the secondary cell 120. At least one pre-configuration may be activated if the associated secondary cell is switched to the primary cell. The at least one pre-configuration may comprise any suitable type of configuration for use when the associated secondary cell is switched to the primary cell.

In some example embodiments, the pre-configuration associated with the secondary cell may involve 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, a Path Loss (PL) reference, a Timing Advance (TA), and/or the like.

For example, the pre-configuration may include resource allocations such as PUCCH resources for HARQ feedback, channel Quality Indicator (CQI) reporting or Scheduling Request (SR), physical Random Access Channel (PRACH) resources, common Search Space (CSS), and any other time, frequency, code, and space resources. The pre-configuration may also include timers, security keys, etc. used in the associated secondary cells when the secondary cells are swapped with the primary cell.

The pre-configuration may be indicated by the network device 105 to the terminal device 110 in the primary cell 115 or the secondary cell 120. In a scenario where terminal device 110 is served by more than one network device, the pre-configuration may be indicated by any one or more of the serving network devices in any one or more of the serving cells.

The first message may be any suitable message including, for example, a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message. For example, in an example embodiment in which the first message comprises a signaling message dedicated to the terminal device 110, the network device 105 may send a pre-configuration, such as Radio Resource Control (RRC) signaling or Medium Access Control (MAC) Control Elements (CEs), to the terminal device 110 in the signaling message dedicated to the terminal device 110. At least a portion of the pre-configuration may also be broadcast by the network device 105 in system information such as a System Information Block (SIB).

If it is determined that a secondary cell of the set of secondary cells is to be exchanged as the primary cell, the network device 105 sends (210) an exchange indication for the exchange to the terminal device 110 via a message separate from the first message, referred to as a second message. In response to DL LBT failure, a primary cell exchange may be triggered at network device 105. For example, the network device 105 may select a secondary cell to be exchanged when DL LBT in the primary cell 115 fails. In some example embodiments, a threshold may be set with respect to the number of DL LBT failures to avoid excessively frequent primary cell exchanges. For example, the network device 105 may determine the exchange when consecutive LBT failures in the primary cell 115 occur N times (where N represents a positive integer).

The primary cell exchange may also be triggered in response to a UL LBT failure. For example, terminal device 110 may send a request for a primary cell exchange to change primary cell 115 upon detecting one or more UL LBT failures. For example, the request may be sent by the terminal device 110 through a MAC CE. In response to the request, the network device 105 may trigger an exchange.

Alternatively, in case more than one network device provides a serving cell, the primary cell exchange may be triggered by the master network device providing the current primary cell. For example, in case the current primary cell is served by a further network device, the further network device may send an indication of DL LBT failure in the primary cell to the network device 105 to trigger the primary cell exchange, e.g. via an X2 interface between the two network devices. Alternatively, the primary cell exchange is performed by a network device serving the corresponding primary cell. For example, the master node sends an exchange indication for PCell and the secondary node sends an exchange indication for PSCell.

For example, the second message may include any suitable message, including a MAC message and a PHY layer message. In an example embodiment where the second message includes a MAC CE, an exchange indication may be sent in the MAC CE to further accelerate the primary cell change. To secure transmission of the MAC CE, authentication information may be included in the MAC CE, for example, the authentication information may include message authentication code integrity (MAC-I) or MAC-I2. Through MAC-I, terminal device 110 may check the integrity of the MAC CE to avoid network attacks.

In some other example embodiments, the second message includes a Physical Downlink Control Channel (PDCCH) command that initiates the random access procedure on the secondary cell to be exchanged as the primary cell. Therefore, the exchange indication may be transmitted in the PDCCH order. For example, the PDCCH order may include a new field for carrying the exchange indication. As another example, an existing field in the PDCCH order may be assigned a new value to indicate the exchange. Other implementations of using PDCCH order to indicate the exchange are possible. The scope of the present disclosure is not limited in this respect.

The exchange indication may identify the secondary cells 120 to exchange in any suitable manner. In some example embodiments, the MAC CE or PDCCH order may be sent by the network device 105 to the terminal device 110 in the secondary cell 120 to be exchanged or changed. When receiving the switch indication in the secondary cell 120, the terminal device 120 may determine that the secondary cell 120 is to be switched to the primary cell. That is, the secondary cell from which the switching indication is received is implicitly considered as the secondary cell to be switched.

In some other example embodiments, the MAC CE or PDCCH order may be scheduled by the network device 105 across carriers in additional secondary cells, with a cell identification (such as a cell index or cell identifier) pointing to the secondary cell to be exchanged as the primary cell. For example, the network device 105 may send a switching indication to the terminal device via the further secondary cell, the switching indication comprising a cell identity of the secondary cell to switch the secondary cell indicated by the cell identity to the primary cell. When more than one secondary cell is preconfigured as a potential primary cell and is cross-scheduled, a cell index or cell identifier may be required.

After sending (210) the exchange indication, the network device 105 receives (215) an exchange acknowledgement from the terminal device 110. In some example embodiments, the acknowledgement may be received from the terminal device 110 by using at least one pre-configuration associated with the secondary cell to be exchanged or changed. For example, in an example embodiment where the exchange indication is sent by the network device 105 in the MAC CE and the at least one pre-configuration includes PUCCH resources in the secondary cell, the terminal device 110 may send HARQ feedback of the MAC CE, such as an Acknowledgement (ACK), using the PUCCH resources as an acknowledgement of the exchange for the secondary cell. Upon receiving the HARQ feedback, the network device 105 knows that the exchange is acknowledged by the terminal device 120.

In at least one example embodiment where the pre-configuration includes PRACH resources in the secondary cell, the terminal device 110 may send a random access request using the PRACH resources as an acknowledgement of the exchange for the secondary cell. In this way, the acknowledgement from the terminal device 110 may be achieved using a Random Access (RA) procedure performed in the secondary cell to be exchanged as the new primary cell. The random access request may include a random access preamble. In some example embodiments, the exchange indication sent by the network device 105 may contain a dedicated preamble for the RA procedure to indicate that the terminal device 110 may initiate the RA procedure using the dedicated preamble to confirm the primary cell exchange or change. In some example embodiments, message 3 (Msg 3) in the RA procedure associated with the pre-configuration from terminal device 110 may be used as an acknowledgement.

After receiving (215) the acknowledgement from the terminal device 110, the network device 105 causes (220) at least one pre-configuration to be activated to switch the associated secondary cell to the primary cell. For example, if the terminal device 110 acknowledges using the RA procedure, a secondary cell to primary cell exchange may be caused at the network device 105 upon receiving a random access request from the terminal device 110. In some example embodiments, the secondary cell to primary cell exchange may be caused at the network device 105 after the RA procedure is completed, after receiving the Msg3 message, or after the network device 105 sends a random access response.

Some example embodiments of the present disclosure provide Control Plane (CP) solutions to enable fast primary cell changes.

After the fast primary cell change/switch is triggered, the network device 105 may cause a handover from the primary cell 115 to the secondary cell 120. For example, the pre-configuration of the secondary cell 120 may include configuration in a higher layer, such as parameters in a Radio Resource Control (RRC) layer. In this case, the Medium Access Control (MAC) entity may instruct the RRC entity to perform the handover and further actions at both the terminal device 110 and the network device 105 using the preconfigured RRC parameters.

In some embodiments, the network device 105 may be configured to perform the primary cell exchange/change based on predefined rules in response to receiving an acknowledgement from the terminal device 110. The predefined rule may indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first TAG is different from the second TAG, the first TAG identity for the first Timing Advance Group (TAG) of the primary cell and the second TAG identity for the second TAG of the secondary cell are interchanged; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, at least one PUCCH to secondary cell mapping for at least one secondary cell within the PUCCH group; reuse of active BWP of the secondary cell in case the secondary cell has been activated, and activation of the first active BWP or initial BWP of the secondary cell in case the secondary cell is deactivated; and switching the primary cell to an activated or deactivated secondary cell.

For illustration and not limitation, in some example embodiments, the network device 105 may cause an exchange of a serving cell ID (referred to as a first serving cell ID) of the primary cell 115 and a serving cell ID (referred to as a second serving cell ID) of the secondary cell 120 to be exchanged as the primary cell according to predefined rules. In the case where the network device 105 serves both the primary cell 115 and the secondary cell 120, the network device 105 may interchange the first and second cell IDs. If the secondary cell 120 is provided by another network device, the network device 105 may communicate with the network device to facilitate the interchange. In some cases, the PCell may be assigned a predefined cell ID (e.g., serving cell ID 0) to distinguish from PSCell and Scell. In this way, the exchange of serving cell IDs of the primary and secondary cells may ensure that the new primary cell has a predefined cell ID. In the scenario where scells switch to pscells, such cell ID interchange may or may not be performed.

In some example embodiments, if the first TAG and the second TAG are different, the network device 105 may cause an exchange of a TAG ID (referred to as a first TAG ID) of the TAG (referred to as a first TAG ID) of the primary cell 115 (e.g., PCell or PSCell) and a TAG ID (referred to as a second TAG ID) of the TAG (referred to as a second TAG) of the secondary cell 120 to be exchanged. Furthermore, the new primary cell changed from the secondary cell 120 can be regarded as the timing reference of the new primary TAG, regardless of whether the secondary cell 120 is used as the timing reference before the exchange. Similar to the interchange of cell IDs, the network device 105 may perform the interchange of TAG IDs when both the primary cell 115 and the secondary cell 120 are provided by the network device 105. If the secondary cell 120 is provided by the network device 105, the network device 105 may facilitate exchange of TAG IDs via communication with another network device.

In some example embodiments, the network device 105 may cause interchange of PUCCH groups according to predefined rules. Also, the interchange may be performed by the network device 105 alone or in cooperation with another network device. For example, when the secondary cell 120 becomes a new primary cell within the PUCCH group, the network device 105 may cause at least one PUCCH of at least one secondary cell within the PUCCH group to map to the secondary cell 120.

For example, if the secondary cell 120 is a PUCCH SCell prior to the swap, when the secondary cell 120 becomes a new PCell, the PUCCH is kept in the same or original PUCCH group by the secondary cell(s) (SCell) mapped to the secondary cell 120. Then the primary cell 115 becomes the PUCCH SCell, while the secondary cell(s) map to the primary cell 115, remaining in the same or primary PUCCH group. When the secondary cell 120 is not a PUCCH SCell (there is no PUCCH mapping from any other secondary cell) before the swap, 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 after the secondary cell 120 swaps to the new PCell, the PUCCH configuration from the original primary cell 115 is disabled. If the secondary cell 120 is within a PUCCH group with a PUCCH SCell, the secondary cell(s) for which the PUCCH is mapped to the PUCCH SCell will be mapped to the new PCell, and PUCCH resources from the original PUCCH SCell are deactivated after the secondary cell 120 is swapped for the new PCell. The primary cell 115 will become the PUCCH SCell, while the SCell(s) mapped to it remain.

Alternatively or additionally, further actions may be related to DL or UL BWP. For example, if the secondary cell has been activated, network device 105 may cause reuse of the active BWP of secondary cell 120 by reusing the active BWP or directing another network device to reuse the activated BWP, in addition to the configured first active BWP exchanged to secondary cell 120. If the secondary cell 120 is deactivated, the first active BWP of the secondary cell 120 or the 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 that the terminal device 110 always switches to the first active BWP (if any) of the secondary cell 120. Terminal device 110 may also negotiate with network device 105 during the pre-configuration phase a BWP to be used after the fast primary cell change or exchange.

In some example embodiments, the primary cell 115 (e.g., PCell or PSCell) is exchanged by the network device 105 for a secondary cell having a maintained configuration. Thus, the network may switch back to the original primary cell 115 when needed. The secondary cell changed from the primary cell 115 may be active or in a deactivated state after the exchange. Alternatively, the original primary cell 115 may be removed. Therefore, only the secondary cell 120 to be exchanged as the primary cell needs to be provided with an identification such as a cell ID, TAG ID, etc.

The CP model or predefined rules may be embodied in RRC procedure text and the new IE for pre-configuration may be embodied in RRC asn.1.

Thus, the terminal device 110 may apply at least one pre-configuration associated with the secondary cell to the communication upon initiation of the RA procedure. For example, a pre-configuration (such as resources, timers, etc.) related to the RA procedure may be applied by the terminal device 110 upon initiation of the RA procedure. Some other pre-configuration may also be applied after initiation of the RA procedure. As another example, the terminal device 110 may apply at least one pre-configuration associated with the secondary cell to the communication after receiving a random access response from the network device 105 or after completion of the RA procedure or after receiving message 4 (Msg 4) from the network device 105.

In addition to the preconfigured activation associated with the secondary cell 120, the terminal device 110 may also perform additional actions for switching from the primary cell 115 to the secondary cell 120. In some example embodiments, the terminal device 110 may exchange the first serving cell ID of the primary cell 115 and the second serving cell ID of the secondary cell 120 after receiving the exchange indication or after the exchange procedure is completed (e.g., after RACH is completed or after HARQ feedback such as an ACK of a MAC CE is sent). The terminal device 110 may also interchange the first TAG ID of the first TAG for the primary cell 115 and the second TAG ID of the second TAG for the secondary cell 120 if the first TAG and the second TAG are different.

In some example embodiments, terminal device 110 may perform actions related to the exchange of PUCCH groups, the enablement or activation of DL or UL BWP, and the exchange of primary cells with activated or deactivated secondary cells, as described above.

For example, in a scenario where the secondary cell to be exchanged is served by the network device 105, the network device 105 may activate a pre-configuration associated with the secondary cell. Alternatively or additionally, in a scenario in which the secondary cell to be exchanged is served by a further network device, the network device 105 sends an activation indication to the further network device, e.g. via the 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 include a security key pre-configured for the secondary cell 120 and enabled after the secondary cell 120 switches to a new primary cell to secure communications. For example, the terminal device 110 may suspend layer 2 (L2) reception after a PDCCH order or MAC CE and then resume with a new key after RACH completion or HARQ ACK. The key may also not be changed during the secondary cell to primary cell exchange.

Example implementations of fast primary cell change are discussed below. In this example, when an RRC connection is established with primary Cell 115 (or Cell 1) on the unlicensed band, terminal device 110 reports to network device 105 its ability to support fast primary Cell changes. When a Cell (or Cell 2) on an unlicensed band is added as a secondary Cell 120 of a terminal device 110, a pre-configuration of all parameters required to switch the secondary Cell 120 to a primary Cell (e.g., PCell or PSCell) is sent to the terminal device 110 via an RRC message, such as an rrcrecon configuration message, from the current serving Cell(s), such as the primary Cell 115. For example, terminal device 110 stores the pre-configuration of Cell2 in the UE variable.

When N (N > 0) LBT failures are detected on Cell and Cell2 quality is good, network device 105 may send UP commands, such as MAC CE or PDCCH commands, for fast primary Cell change to terminal device 110 via Cell 2. Upon receiving the UP command, terminal device 110 enables the stored pre-configuration of Cell2 to change Cell2 to the primary Cell (e.g., PCell or PSCell) and Cell1 to the secondary Cell. The network device 105 may be acknowledged with RACH access to Cell2 or HARQ feedback to downlink MAC CE as an acknowledgement of the received UP command. When an acknowledgement is received from terminal device 110, network device 115 locally enables the stored pre-configuration to configure Cell2 as the primary Cell and Cell1 as the secondary Cell.

Fig. 3 illustrates a flowchart of an example method 300 according to some example embodiments of the present disclosure. The method 300 may be implemented by the network device 105 as shown in fig. 1. For discussion purposes, the method 300 will be described with reference to FIG. 1.

At block 305, the network device 105 sends a set of preconfigurations to the terminal device 110 via a first message. At least one of the set of pre-configurations is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell.

At block 310, the network device 105 sends a switching indication to the terminal device 110 for switching the secondary cells of the group of secondary cells to the primary cell via a separate second message. At block 315, in response to receiving an acknowledgement for the exchange from terminal device 110, network device 105 causes at least one pre-configuration associated with the secondary cell to be activated.

In some example embodiments, the first message comprises a signaling message specific to the terminal device. The network device 105 sends the set of pre-configurations in a signaling message dedicated to the terminal device 110.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE). The network device 105 sends an exchange 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 includes a Physical Downlink Control Channel (PDCCH) command. The network device 105 sends an exchange indication in the PDCCH order. The PDCCH order may include a field for carrying an exchange 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 acknowledgement from the terminal device 110 using at least one pre-configuration associated with the secondary cell.

In some example embodiments, if the second message includes a Media Access Control (MAC) Control Element (CE) and the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, the network device 105 may receive hybrid automatic repeat request (HARQ) feedback for the MAC CE as an acknowledgement from the terminal device using the PUCCH resources.

In some example embodiments, the network device 105 may receive a random access request from the terminal device as an acknowledgement using Physical Random Access Channel (PRACH) resources in the secondary cell if the at least one pre-configuration associated with the secondary cell includes PRACH resources. In some example embodiments, the exchange indication may include a dedicated preamble for the random access request.

In some example embodiments, the network device 105 sends a random access response to the terminal device 110 after receiving the random access request from the terminal device 110. Further, the network device 105 activates at least one pre-configuration associated with the secondary cell. In some other example embodiments, the network device 105 may activate at least one pre-configuration associated with the secondary cell after the terminal device 110 completes a random access procedure initiated using the random access request.

In some example embodiments, the network device 105 may send a switch indication in the secondary cell via a second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, the network device 105 may select a secondary cell from the set of secondary cells to be exchanged as the primary cell in response to at least one of a downlink Listen Before Talk (LBT) failure in the current primary cell and a request from the terminal device 110 for a primary cell exchange.

In some example embodiments, additional secondary cells in the set of secondary cells are served by the network device 105. In these embodiments, the network device 105 may send a switching indication to the terminal device 110 via the second message in the further secondary cell, and the switching indication comprises a cell identity of the secondary cell to switch the secondary cell indicated by the cell identity to 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 at least one pre-configuration associated with the secondary cell.

In some example embodiments, the at least one pre-configuration includes a configuration required for the cell to function as a primary cell. For example, the at least one pre-configuration may include at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for 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 include one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message may include one of a MAC message and a PHY layer message.

In some example embodiments, the network device 105 may perform the exchange based on predefined rules in response to receiving the acknowledgement. The predefined rule may indicate at least one of: interchange of a first serving cell identity for the primary cell 115 and a second serving cell identity for the secondary cell 110; in case the first TAG is different from the second TAG, the first TAG ID of the first TAG for the primary cell 115 and the second TAG ID of the second TAG for the secondary cell 120 are interchanged; when the secondary cell 120 becomes a new primary cell within the PUCCH group, at least one PUCCH-to-secondary cell mapping for at least one secondary cell within the PUCCH group; reuse of active BWP of secondary cell 120 in case secondary cell 120 has been activated, and activation of the first active BWP or initial BWP of secondary cell 120 in case secondary cell 120 is deactivated; and switching the original primary cell 115 to an activated or deactivated secondary cell.

Fig. 4 illustrates a flowchart of an example method 400 according to some example embodiments of the present disclosure. The method 400 may be implemented by the terminal device 110 as shown in fig. 1. For discussion purposes, the method 400 will be described with reference to fig. 1.

At block 405, terminal device 110 receives a set of preconfigurations from network device 105 via a first message. At least one of the set of pre-configurations is associated with a secondary cell of the set of secondary cells and is activated if the associated secondary cell is switched to the primary cell.

At block 410, terminal device 110 receives a switch indication from network device 105 via a separate second message for switching the secondary cells of the set of secondary cells to the primary cell. At block 415, terminal device 110 sends an acknowledgement for the exchange to network device 105.

In some example embodiments, the terminal device 110 may receive a random access response from the network device. Terminal device 110 may then apply at least one pre-configuration associated with the secondary cell to the communication. In some example embodiments, the terminal device 110 may apply at least one pre-configuration associated with the secondary cell to the communication after completion of the random access procedure initiated using the random access request. In some other example embodiments, the terminal device 110 may apply at least one pre-configuration associated with the secondary cell to the communication after initiation of the random access procedure.

In some example embodiments, in response to an uplink LBT failure in the current primary cell, terminal device 110 may send a request for primary cell exchange to the network device.

In some example embodiments, terminal device 110 may perform the exchange based on predefined rules. The predefined rule may indicate at least one of: exchanging a first serving cell identity for the primary cell 115 and a second serving cell identity for the secondary cell 110; in case the first TAG is different from the second TAG, the first TAG ID of the first TAG for the primary cell 115 and the second TAG ID of the second TAG for the secondary cell 120 are interchanged; when the secondary cell 120 becomes a new primary cell within the PUCCH group, mapping at least one PUCCH for at least one secondary cell within the PUCCH group to the secondary cell 120; reusing the active BWP of the secondary cell 120 in case the secondary cell 120 has been activated, and exchanging the first active BWP or the initial BWP to the secondary cell 120 in case the secondary cell 120 is deactivated; and switching the original primary cell 115 to an activated or deactivated secondary cell.

All of the operations and features described above with reference to fig. 1 and 2 are equally applicable to and have similar effects on methods 300 and 400. Details will be omitted for simplicity.

In some example embodiments, the methods 300 and 400 described above with reference to fig. 1-4 may be performed by an apparatus comprising means for performing the respective steps of the methods 300 and 400. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

Fig. 5 is a simplified block diagram of an apparatus 500 suitable for implementing example embodiments of the present disclosure. Device 500 may be implemented at or as part of network device 105 or 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. Memory 520 stores at least program 540. The communication module 530 is used for bi-directional communication, for example, via multiple antennas. The communication interface may represent any interface required for communication.

The program 540 is assumed to include program instructions that, when executed by the associated processor 510, enable the apparatus 500 to operate in accordance with example embodiments of the present disclosure, as discussed herein with reference to fig. 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.

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 non-transitory computer readable storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory, as non-limiting examples. Although only one memory 520 is shown in device 500, there may be several physically distinct memory modules in device 500. Processor 510 may be of any type suitable to the local technology network and may include, by way of non-limiting example, one or more of a general purpose computer, a special purpose computer, a microprocessor, a Digital Signal Processor (DSP), and a processor based on a multi-core processor architecture. The device 500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock that is synchronized to the master processor.

When device 500 is used as network device 105 or as part of network device 105, processor 510 and communication module 530 may cooperate to implement method 300 as described above with reference to fig. 3. When device 500 is used as terminal device 110 or as part of terminal device 110, processor 510 and communication module 530 may cooperate to implement method 400 as described above with reference to fig. 4.

All of the operations and features described above with reference to fig. 1-4 are equally applicable to the apparatus 500 and have similar effects. Details will be omitted for simplicity.

In general, the various example embodiments of the 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 the example embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in 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, that are executed in a device on a target real or virtual processor to perform the methods 300 and 400 described above with reference to fig. 1-4. Generally, program modules include routines, programs, libraries, objects, classes, components, data types, etc. 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 local or distributed devices. In distributed devices, program modules may be located in both local and remote memory storage media.

Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program code 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 code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the 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 this disclosure, computer program code or related data may be carried by any suitable carrier to enable an apparatus, device, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer readable media, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus or devices, or any suitable combination thereof. More specific examples of a computer-readable storage medium 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), a Digital Versatile Disc (DVD), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Moreover, although 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 some cases, multitasking and parallel processing may be advantageous. Also, while the above discussion contains several specific implementation details, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features 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 can also be implemented in multiple exemplary embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the 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 technology have been described. In addition to or instead of the above, the following examples are described. The features described in any of the examples below may be used with any of the other examples described herein.

In some aspects, an apparatus comprises: at least one processor; 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 apparatus to: transmitting a set of pre-configurations to the terminal device via a first message, at least one pre-configuration of the set of pre-configurations being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is switched to the primary cell; transmitting a switching indication for switching a secondary cell of the group of secondary cells to the primary cell via a separate second message to the terminal device; and causing at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the secondary cell is served by the device, and the device is caused to send the exchange indication by: a switching indication in the secondary cell is sent to the terminal device via a second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the apparatus is caused to receive the acknowledgement by: hybrid automatic repeat request (HARQ) feedback for the MAC CE is received as an acknowledgement from the terminal device using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and the apparatus is caused to receive the acknowledgement by: a random access request is received as an acknowledgement from the terminal device using PRACH resources.

In some example embodiments, the exchange indication includes a dedicated preamble for the random access request, and the apparatus causes at least one pre-configuration associated with the secondary cell to be activated by: in response to receiving the random access request, sending a random access response to the terminal equipment; and activating at least one pre-configuration associated with the secondary cell after at least one of: transmission of a 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 is further caused to: a secondary cell to be exchanged as a primary cell is selected from the set of secondary cells in response to at least one of a downlink Listen Before Talk (LBT) failure in the current primary cell and a request from the terminal device for a primary cell exchange.

In some example embodiments, the further secondary cells of the set of secondary cells are served by the device, and the device is caused to send the exchange indication by: and transmitting a switching indication including a cell identity of the secondary cell to the terminal device via a second message in the further secondary cell to switch the secondary cell indicated by the cell identity to the primary cell.

In some example embodiments, the secondary cell is served by a further device, and the device causes at least one pre-configuration associated with the secondary cell to be activated by: an activation indication is sent to the further device to activate 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 includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 is further caused to perform an exchange based on predefined rules in response to receiving the acknowledgement, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, the first TAG identity of the first TAG for the primary cell and the second TAG identity of the second TAG for the secondary cell are interchanged; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, at least one PUCCH to secondary cell mapping for at least one secondary cell within the PUCCH group; reuse of active BWP of the secondary cell in case the secondary cell has been activated before the exchange, and activation of the first active BWP or initial BWP of the secondary cell in case the secondary cell is deactivated before the exchange; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, an apparatus comprises: at least one processor; 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 apparatus to: receiving a set of pre-configurations from the network device via a first message, at least one pre-configuration of the set of at least one pre-configuration being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is switched to the primary cell; receiving a switching indication from the network device via a separate second message for switching a secondary cell of the group of secondary cells to a primary cell; and sending an acknowledgement for the exchange to the network device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the apparatus is caused to transmit the acknowledgement by: hybrid automatic repeat request (HARQ) feedback for the MAC CE is sent to the network device as an acknowledgement using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and the apparatus is caused to transmit the acknowledgement by: a random access request is sent as an acknowledgement to the network device using PRACH resources.

In some example embodiments, the exchange indication comprises a dedicated preamble for the random access request, and the apparatus is further caused to: applying at least one pre-configuration associated with the secondary cell to the communication after at least one of: the method comprises the steps of initiating a random access procedure using a random access request, receiving a random access response from a network device, and completing the random access procedure initiated using the random access request.

In some example embodiments, the apparatus is caused to receive the exchange indication by: a switching indication is received in the secondary cell from the network device via a second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, the apparatus is caused to receive the exchange indication by: a switching indication comprising a cell identity of the secondary cell is received in the further secondary cell from the network device via the second message for switching the secondary cell indicated by the cell identity to the primary cell.

In some example embodiments, the apparatus is further caused to: in response to an uplink LBT failure in the current primary cell, a request for primary cell switching is sent to the network device.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 is further caused to perform the exchanging based on predefined rules, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, exchanging a first TAG identity of the first TAG for the primary cell and a second TAG identity of the second TAG for the secondary cell; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, mapping at least one PUCCH for at least one secondary cell within the PUCCH group to the secondary cell; reusing the active BWP of the secondary cell in case the secondary cell has been activated before the switching, and switching to the first active BWP or the initial BWP of the secondary cell in case the secondary cell is deactivated before the switching; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, a method comprises: transmitting, at the network device, a set of pre-configurations to the terminal device via a first message, at least one pre-configuration of the set of pre-configurations being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is switched to the primary cell; transmitting a switching indication for switching a secondary cell of the group of secondary cells to the primary cell via a separate second message to the terminal device; and causing at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the secondary cell is served by the device, and transmitting the exchange indication includes: a switching indication is sent in the secondary cell to the terminal device via a second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and receiving the acknowledgement includes: hybrid automatic repeat request (HARQ) feedback for the MAC CE is received as an acknowledgement from the terminal device using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and receiving the acknowledgement includes: a random access request is received as an acknowledgement from the terminal device using PRACH resources.

In some example embodiments, the exchange indication includes a dedicated preamble for the random access request, and causing at least one pre-configuration associated with the secondary cell to be activated includes: in response to receiving the random access request, sending a random access response to the terminal equipment; and activating at least one pre-configuration associated with the secondary cell after at least one of: transmission of a 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: a secondary cell to be exchanged as a primary cell is selected from the set of secondary cells in response to at least one of a downlink Listen Before Talk (LBT) failure in the current primary cell and a request from the terminal device for a primary cell exchange.

In some example embodiments, the further secondary cells of the set of secondary cells are served by the device, and transmitting the switch indication comprises: and transmitting a switching indication including the cell identity of the secondary cell to the terminal device in the further secondary cell to switch the secondary cell indicated by the cell identity to the primary cell.

In some example embodiments, the secondary cell is served by a further network device, and causing at least one pre-configuration associated with the secondary cell to be activated comprises: an activation indication is sent to the further network device to activate 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 includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 an exchange based on predefined rules in response to receiving the acknowledgement, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, the first TAG identity of the first TAG for the primary cell and the second TAG identity of the second TAG for the secondary cell are interchanged; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, at least one PUCCH to secondary cell mapping for at least one secondary cell within the PUCCH group; reuse of active BWP of the secondary cell in case the secondary cell has been activated before the exchange, and activation of the first active BWP or initial BWP of the secondary cell in case the secondary cell is deactivated before the exchange; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, a method comprises: receiving, at the terminal device, a set of pre-configurations from the network device via a first message, at least one pre-configuration of the set of pre-configurations being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is exchanged for the primary cell; receiving a switching indication from the network device via a separate second message for switching a secondary cell of the group of secondary cells to a primary cell; and sending an acknowledgement for the exchange to the network device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and transmitting the acknowledgement includes: hybrid automatic repeat request (HARQ) feedback for the MAC CE is sent to the network device as an acknowledgement using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and transmitting the acknowledgement includes: a random access request is sent as an acknowledgement to the network device using PRACH resources.

In some example embodiments, the exchange indication comprises a dedicated preamble for the random access request, and the method further comprises: applying at least one pre-configuration associated with the secondary cell to the communication after at least one of: the method comprises the steps of initiating a random access procedure using a random access request, receiving a random access response from a network device, and completing the random access procedure initiated using the random access request.

In some example embodiments, receiving the exchange indication includes: a switching indication is received in the secondary cell from the network device via a second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, receiving the exchange indication includes: a switching indication comprising a cell identity of the secondary cell is received in the further secondary cell from the network device via the second message for switching the secondary cell indicated by the cell identity to the primary cell.

In some preferred embodiments, the method further comprises: in response to an uplink LBT failure in the current primary cell, a request for primary cell switching is sent to the network device.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 an exchange based on predefined rules, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, exchanging a first TAG identity of the first TAG for the primary cell and a second TAG identity of the second TAG for the secondary cell; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, mapping at least one PUCCH for at least one secondary cell within the PUCCH group to the secondary cell; reusing the active BWP of the secondary cell in case the secondary cell has been activated before the switching, and switching to the first active BWP or the initial BWP of the secondary cell in case the secondary cell is deactivated before the switching; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, an apparatus comprises: means for sending, at the network device, a set of pre-configurations to the terminal device via a first message, at least one pre-configuration of the set of pre-configurations being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is switched to the primary cell; means for sending a switching indication for switching a secondary cell of the group of secondary cells to the primary cell via a separate second message to the terminal device; and means for causing at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the secondary cell is served by the device, and the means for sending the exchange indication comprises: means for sending a switching indication to the terminal device in the secondary cell via the second message to indicate that the secondary cell is to be switched to the primary cell.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the means for receiving the acknowledgement includes: means for receiving hybrid automatic repeat request (HARQ) feedback for the MAC CE as an acknowledgement from the terminal device using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and the means for receiving the acknowledgement includes: means for receiving a random access request as an acknowledgement from the terminal device using the PRACH resource.

In some example embodiments, the exchange indication comprises a dedicated preamble for the random access request, and the means for causing at least one pre-configuration associated with the secondary cell to be activated comprises means for: in response to receiving the random access request, sending a random access response to the terminal equipment; and activating at least one pre-configuration associated with the secondary cell after at least one of: transmission of a 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 a secondary cell from the set of secondary cells to be exchanged as a primary cell in response to at least one of a downlink Listen Before Talk (LBT) failure in a current primary cell and a request from a terminal device for a primary cell exchange.

In some example embodiments, the further secondary cells of the set of secondary cells are served by the device, and the means for sending the exchange indication comprises: and means for transmitting a switching indication including a cell identity of the secondary cell to the terminal device in the further secondary cell to switch the secondary cell indicated by the cell identity to the primary cell.

In some example embodiments, the secondary cell is served by a further network device, and the means for causing 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 at least one pre-configured associated with the secondary cell.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 an exchange based on predefined rules in response to receiving the acknowledgement, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, the first TAG identity of the first TAG for the primary cell and the second TAG identity of the second TAG for the secondary cell are interchanged; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, at least one PUCCH to secondary cell mapping for at least one secondary cell within the PUCCH group; reuse of active BWP of the secondary cell in case the secondary cell has been activated before the exchange, and activation of the first active BWP or initial BWP of the secondary cell in case the secondary cell is deactivated before the exchange; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, an apparatus comprises: means for receiving, at the terminal device, a set of pre-configurations from the network device via a separate second message, at least one pre-configuration of the set of pre-configurations being associated with a secondary cell of the set of secondary cells and being activated if the associated secondary cell is exchanged for the primary cell; means for receiving a switching indication from the network device via a separate second message for switching a secondary cell of the group of secondary cells to a primary cell; and means for sending an acknowledgement for the exchange to the network device.

In some example embodiments, the first message includes one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, and a Physical (PHY) layer message, and the second message includes one of a MAC message and a PHY layer message.

In some example embodiments, the second message includes 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 includes a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command includes a field for carrying the exchange indication.

In some example embodiments, the second message includes a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell includes Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the means for transmitting the acknowledgement includes: means for sending hybrid automatic repeat request (HARQ) feedback for the MAC CE as an acknowledgement to the network device using the PUCCH resource.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes Physical Random Access Channel (PRACH) resources in the secondary cell, and the means for transmitting the acknowledgement includes: means for sending a random access request as an acknowledgement to the network device using the PRACH resource.

In some example embodiments, the exchange indication includes a dedicated preamble for the random access request, and the apparatus further comprises: means for applying at least one pre-configuration associated with the secondary cell to the communication after at least one of: the method comprises the steps of initiating a random access procedure using a random access request, receiving a random access response from a network device, and completing the random access procedure initiated using the random access request.

In some example embodiments, the means for receiving the exchange indication from the network device via the second message comprises: means for receiving a switch indication in the secondary cell, indicating that the secondary cell is to be switched to the primary cell.

In some example embodiments, the means for receiving an indication of an exchange comprises: means for receiving, in the further secondary cell, a switching indication comprising a cell identity of the secondary cell from the network device via the second message, for switching the secondary cell indicated by the cell identity to the primary cell.

In some example embodiments, the apparatus further comprises: means for sending a request for primary cell switching to the network device in response to an uplink LBT failure in the current primary cell.

In some example embodiments, the at least one pre-configuration associated with the secondary cell includes at least one of: a security key for communication in a secondary cell, a Physical Uplink Control Channel (PUCCH) resource for hybrid automatic repeat request (HARQ) feedback or 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 an exchange based on predefined rules, wherein the predefined rules indicate at least one of: exchanging a first service cell identifier for an original primary cell and a second service cell identifier for a secondary cell; in case the first Timing Advance Group (TAG) is different from the second TAG, exchanging a first TAG identity of the first TAG for the primary cell and a second TAG identity of the second TAG for the secondary cell; when a secondary cell becomes a new primary cell within a Physical Uplink Control Channel (PUCCH) group, mapping at least one PUCCH for at least one secondary cell within the PUCCH group to the secondary cell; reusing the active BWP of the secondary cell in case the secondary cell has been activated before the switching, and switching to the first active BWP or the initial BWP of the secondary cell in case the secondary cell is deactivated before the switching; and switching the primary cell to an activated or deactivated secondary cell.

In some aspects, a computer-readable storage medium includes program instructions stored thereon, which when executed by a processor of a device, cause the device to perform a method according to some example embodiments of the present disclosure.

Claims (40)

1. An apparatus for communication, comprising:

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 apparatus to:

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

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

causing the at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

A security key for communications in the secondary cell,

physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

at least one timer.

2. The apparatus of claim 1, wherein the first message comprises one of a radio resource control message, a Medium 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.

3. The apparatus of claim 1, wherein the second message comprises a Media Access Control (MAC) Control Element (CE), and the MAC CE comprises message authentication code integrity as authentication information.

4. The apparatus of claim 1, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) command comprising a field for carrying the exchange indication.

5. An apparatus according to claim 1, wherein the secondary cell is served by the apparatus, and the apparatus is caused to send the exchange indication by:

the switching indication is sent in the secondary cell to the terminal device via the second message to indicate that the secondary cell is to be switched to a primary cell.

6. The apparatus of claim 5, wherein the second message comprises a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell comprises Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the apparatus is caused to receive the acknowledgement by:

and receiving hybrid automatic repeat request feedback for the MAC CE from the terminal equipment by using the PUCCH resource as the acknowledgement.

7. The apparatus of claim 5, wherein the at least one pre-configuration associated with the secondary cell comprises Physical Random Access Channel (PRACH) resources in the secondary cell, and the apparatus is caused to receive the acknowledgement by:

and receiving a random access request from the terminal equipment as the acknowledgement by using the PRACH resource.

8. The apparatus of claim 7, wherein the exchange indication comprises a dedicated preamble for the random access request, and the apparatus causes the at least one pre-configuration associated with the secondary cell to be activated by:

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

Activating the at least one pre-configuration associated with the secondary cell after at least one of:

said transmitting of said random access response, and

completion of the random access procedure initiated by the terminal device using the random access request.

9. The apparatus of claim 5, wherein the apparatus is further caused to:

the secondary cell to be exchanged as the primary cell is selected from the set of secondary cells in response to at least one of a downlink listen before talk failure in a current primary cell and a request from the terminal device for a primary cell exchange.

10. The apparatus of claim 1, wherein a further secondary cell of the set of secondary cells is served by the apparatus, and the apparatus is caused to send the exchange indication by:

transmitting, in the further secondary cell, the exchange indication comprising a cell identity for the secondary cell to the terminal device via the second message to exchange the secondary cell indicated by the cell identity for the primary cell.

11. 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:

An activation indication is sent to the further device to activate the at least one pre-configuration associated with the secondary cell.

12. The apparatus of claim 1, wherein the apparatus is further caused to perform the exchange based on a predefined rule in response to receiving the acknowledgement, wherein the predefined rule indicates at least one of:

the exchange of a first serving cell identity for the primary cell and a second serving cell identity for the secondary cell,

the exchange of a first TAG identity for a first Timing Advance Group (TAG) of the primary cell and a second TAG identity for a second TAG of the secondary cell is performed in the following cases: the first TAG is different from the second TAG,

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

reuse of active bandwidth parts (BWP) of the secondary cell in case the secondary cell has been activated before the exchange, and activation of a first active BWP or an initial BWP of the secondary cell in case the secondary cell is deactivated before the exchange, and

And exchanging the primary main cell with an activated or deactivated secondary cell.

13. An apparatus for communication, comprising:

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 apparatus to:

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

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

transmitting an acknowledgement for the exchange to the network device;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communications in the secondary cell,

physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

At least one timer.

14. The apparatus of claim 13, wherein the first message comprises one of a radio resource control message, a Medium 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.

15. The apparatus of claim 13, wherein the second message comprises a Media Access Control (MAC) Control Element (CE), and the MAC CE comprises message authentication code integrity as authentication information.

16. The apparatus of claim 13, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) command, and the PDCCH command comprises a field for carrying the exchange indication.

17. The apparatus of claim 13, wherein the second message comprises a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell comprises Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and the apparatus is caused to send the acknowledgement by:

and sending hybrid automatic repeat request feedback for the MAC CE to the network equipment by using the PUCCH resource as the acknowledgement.

18. The apparatus of claim 13, wherein the at least one pre-configuration associated with the secondary cell comprises Physical Random Access Channel (PRACH) resources in the secondary cell, and the apparatus is caused to send the acknowledgement by:

and sending a random access request to the network equipment by using the PRACH resource as the confirmation.

19. The apparatus of claim 18, wherein the exchange indication comprises a dedicated preamble for the random access request, and the apparatus is further caused to:

applying the at least one pre-configuration associated with the secondary cell to communications at a sum of at least one of:

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

receiving a random access response from the network device, and

completion of the random access procedure initiated using the random access request.

20. An apparatus according to claim 13, wherein the apparatus is caused to receive the exchange indication by:

the switching indication is received in the secondary cell from the network device via the second message to indicate that the secondary cell is to be switched to a primary cell.

21. An apparatus according to claim 13, wherein the apparatus is caused to receive the exchange indication by:

the switching indication comprising a cell identity for the secondary cell is received in a further secondary cell from the network device via the second message for switching the secondary cell indicated by the cell identity to the primary cell.

22. The apparatus of claim 13, wherein the apparatus is further caused to:

a request for a primary cell switch is sent to the network device in response to an uplink listen before talk failure in the current primary cell.

23. The apparatus of claim 13, wherein the apparatus is further caused to perform the exchange based on predefined rules, wherein the predefined rules indicate at least one of:

exchanging a first serving cell identity for an original primary cell and a second serving cell identity for said secondary cell,

the first TAG identity for a first Timing Advance Group (TAG) of the primary cell and the second TAG identity for a second TAG of the secondary cell are interchanged in the following case: the first TAG is different from the second TAG,

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

Reusing an active bandwidth part (BWP) of the secondary cell in case the secondary cell has been activated before the exchanging, and exchanging a first active BWP or an initial BWP to the secondary cell in case the secondary cell is deactivated before the exchanging, and

and exchanging the primary main cell with an activated or deactivated secondary cell.

24. A method for communication, comprising:

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

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

causing the at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement from the terminal device for the exchange;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communications in the secondary cell,

Physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

at least one timer.

25. The method of claim 24, further comprising performing the exchange based on predefined rules in response to receiving the acknowledgement, wherein the predefined rules indicate at least one of:

the exchange of a first serving cell identity for the primary cell and a second serving cell identity for the secondary cell,

the exchange of a first TAG identity for a first Timing Advance Group (TAG) of the primary cell and a second TAG identity for a second TAG of the secondary cell is performed in the following cases: the first TAG is different from the second TAG,

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

reuse of active bandwidth parts (BWP) of the secondary cell in case the secondary cell has been activated before the exchange, and activation of a first active BWP or an initial BWP of the secondary cell in case the secondary cell is deactivated before the exchange, and

And exchanging the primary main cell with an activated or deactivated secondary cell.

26. A method for communication, comprising:

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

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

transmitting an acknowledgement for the exchange to the network device;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communications in the secondary cell,

physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

at least one timer.

27. The method of claim 26, wherein the first message comprises one of a radio resource control message, a Medium 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.

28. The method of claim 26, wherein the second message comprises a Media Access Control (MAC) Control Element (CE), and the MAC CE comprises message authentication code integrity as authentication information.

29. The method of claim 26, wherein the second message comprises a Physical Downlink Control Channel (PDCCH) command and the PDCCH command comprises a field for carrying the exchange indication.

30. The method of claim 26, wherein the second message comprises a Medium Access Control (MAC) Control Element (CE), the at least one pre-configuration associated with the secondary cell comprises Physical Uplink Control Channel (PUCCH) resources in the secondary cell, and transmitting the acknowledgement comprises:

and sending hybrid automatic repeat request feedback for the MAC CE to the network equipment by using the PUCCH resource as the acknowledgement.

31. The method of claim 26, wherein the at least one pre-configuration associated with the secondary cell comprises Physical Random Access Channel (PRACH) resources in the secondary cell, and transmitting the acknowledgement comprises:

and sending a random access request to the network equipment by using the PRACH resource as the confirmation.

32. The method of claim 31, wherein the exchange indication comprises 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 to communications after at least one of:

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

receiving a random access response from the network device, and

completion of the random access procedure initiated using the random access request.

33. The method of claim 26, wherein receiving the exchange indication comprises:

the switching indication is received in the secondary cell from the network device via the second message to indicate that the secondary cell is to be switched to a primary cell.

34. The method of claim 26, wherein receiving the exchange indication comprises:

the switching indication comprising a cell identity for the secondary cell is received in a further secondary cell from the network device via the second message for switching the secondary cell indicated by the cell identity to the primary cell.

35. The method of claim 26, further comprising:

A request for a primary cell switch is sent to the network device in response to an uplink listen before talk failure in the current primary cell.

36. The method of claim 26, further comprising performing the exchange based on predefined rules, wherein the predefined rules indicate at least one of:

exchanging a first serving cell identity for an original primary cell and a second serving cell identity for said secondary cell,

the first TAG identity for a first Timing Advance Group (TAG) of the primary cell and the second TAG identity for a second TAG of the secondary cell are interchanged in the following case: the first TAG is different from the second TAG,

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

reusing active BWP of the secondary cell in case the secondary cell has been activated before the exchange, and exchanging first active BWP or initial BWP to the secondary cell in case the secondary cell has been deactivated before the exchange, and

and exchanging the primary main cell with an activated or deactivated secondary cell.

37. An apparatus for communication, comprising:

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

means for sending a switching indication to the terminal device for switching the secondary cells of the set of secondary cells to primary cells via a separate second message; and

means for causing the at least one pre-configuration associated with the secondary cell to be activated in response to receiving an acknowledgement for the exchange from the terminal device;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communications in the secondary cell,

physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

at least one timer.

38. An apparatus for communication, comprising:

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

Means for receiving a switching indication from the network device via a separate second message for switching the secondary cells of the set of secondary cells to primary cells; and

means for sending an acknowledgement for the exchange to the network device;

wherein the at least one pre-configuration associated with the secondary cell comprises at least one of:

a security key for communications in the secondary cell,

physical uplink control channel resources for hybrid automatic repeat request feedback or scheduling requests,

the physical random access channel resources are allocated to the mobile station,

a common search space, and

at least one timer.

39. A computer readable storage medium comprising program instructions stored thereon, which when executed by a processor of a device, cause the device to perform the method of any of claims 24 to 25.

40. A computer readable storage medium comprising program instructions stored thereon, which when executed by a processor of a device, cause the device to perform the method of any of claims 26 to 36.