Enhanced carrier aggregation replacement handling for base stations

Abstract

A base station is configured to operate with a user equipment (UE) in a carrier aggregation (CA) mode, wherein the base station operates as a special cell (SpCell) or at least one secondary cell (SCell) in the CA mode; performing a CA replacement operation with the UE, the CA replacement operation including at least one of the following: when the base station operates as the SpCell, the base station becomes a new SCell; or when the base station operates as the at least one SCell, the base station becomes a new SpCell.

Description

[0001] Priority / Incorporation by Reference

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 376,469, filed on September 21, 2022, entitled “Enhanced Carrier Aggregation Swap Handling,” the entire text of which is incorporated herein by reference. Background Art

[0003] A typical carrier aggregation (CA) scheme is characterized by a master cell group (MCG), which is characterized in that the master cell (PCell) can act as an anchor for configuring a secondary cell (SCell). This scheme is used to increase frequency resources to achieve faster throughput. Similarly, the anchor of the secondary cell group (SCG) is the PSCell, which can configure the SCG SCell. The PSCell (or PSCell) should always operate in both the uplink and downlink, while the SCell should only operate in the downlink. The PCell and / or PSCell may also be referred to as a special cell (SpCell).

[0004] The SPCell carries the Physical Uplink Control Channel (PUCCH), which is used as a feedback channel during uplink operation. In CA operation, there may be two PUCCHs operating simultaneously; the second PUCCH operates on the SCell (PUCCH SCell). All serving cells in CA operate with synchronized time / cell system frame number (SFN), except during operation in asynchronous CA, where there may be two different timing groups.

[0005] When a user equipment (UE) is operating in connected mode with a SpCell (or during transition to connected mode), the SpCell may provide a radio resource control (RRC) configuration message containing the SCell configuration to the UE. The SpCell common configuration cannot be changed without performing a ReconfigurationWithSync operation. The SCell common configuration cannot be changed without releasing the SCell and adding the SCell again. Summary of the invention

[0006] Some exemplary embodiments relate to a base station device having a processing circuit configured to: operate with a user equipment (UE) in a carrier aggregation (CA) mode, wherein the base station operates as a special cell (SpCell) or at least one secondary cell (SCell) in the CA mode; perform a CA replacement operation with the UE, the CA replacement operation comprising at least one of the following: when the base station operates as the SpCell, the base station becomes a new SCell; or when the base station operates as the at least one SCell, the base station becomes a new SpCell.

[0007] Other exemplary embodiments relate to a method performed by a base station. The method includes operating with a user equipment (UE) in a carrier aggregation (CA) mode, wherein the base station operates as a special cell (SpCell) or at least one secondary cell (SCell) in the CA mode; performing a CA replacement operation with the UE, the CA replacement operation including at least one of the following: when the base station operates as the SpCell, the base station becomes a new SCell; or when the base station operates as the at least one SCell, the base station becomes a new SpCell. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Exemplary network arrangements are shown according to various exemplary embodiments.

[0009] Figure 2 An exemplary UE according to various exemplary embodiments is shown.

[0010] Figure 3 An exemplary base station according to various exemplary embodiments is shown.

[0011] Figure 4 Depicted is a signaling diagram for a network-triggered SpCell to SCell handover according to various exemplary embodiments.

[0012] Figure 5 Depicted is a signaling diagram for SpCell to SCell handover triggered by a UE according to various exemplary embodiments.

[0013] 6A depicts a first information element in ASN.1 for SpCell configuration according to various exemplary embodiments.

[0014] 6B illustrates a second information element for SCell configuration in ASN.1 according to various exemplary embodiments.

[0015] 7A illustrates a first information element in ASN.1 including information on whether synchronization during CA should be applied when a cell is changed to a SpCell, according to various exemplary embodiments.

[0016] 7B illustrates a second information element in ASN.1 including information regarding whether synchronization during CA should be applied when a cell is changed to a SpCell, according to various exemplary embodiments.

[0017] Figure 8 Depicted are information elements in ASN.1 for SpCell configuration that include information related to data path resetting during CA replacement, according to various exemplary embodiments.

[0018] Fig. 9 Depicted are information elements for SpCell configuration in ASN.1, including information related to SCell activation status after CA replacement, according to various exemplary embodiments.

[0019] 10A illustrates a first information element in ASN.1 including information related to serving cell validity after CA change, according to various exemplary embodiments.

[0020] 10B illustrates a second information element in ASN.1 including information related to serving cell validity after CA change, according to various exemplary embodiments.

[0021] Fig.11 Depicted is a downlink (DL) downlink control information (DCI) L1CA replacement structure according to various exemplary embodiments.

[0022] Fig.12 A first example Medium Access Control - Control Element (MAC-CE) CA replacement structure is depicted in accordance with various exemplary embodiments.

[0023] Fig.13 A second example medium access control - control element (MAC-CE) CA replacement structure 1200 is depicted in accordance with various exemplary embodiments. DETAILED DESCRIPTION

[0024] The exemplary embodiments may be further understood with reference to the following description and associated drawings, wherein like elements are provided with like reference numerals.The exemplary embodiments relate to improved handling of layer 1 (L1) or layer 2 (L2) SpCell replacements through a network.

[0025] SpCell replacement is an operation in which a SpCell (e.g., a PCell in a primary cell group (PCG) or a PSCell in a secondary cell group (SCG)) changes roles with a corresponding SCell in a PCG or SCG (also called "CA replacement"). For example, a PCell of a PCG may become an SCell of the PCG, and a SCell of a PCG may become an PCell of the PCG, i.e., the PCell and the SCell change roles in the PCG. Similarly, a PSCell of an SCG may become an SCell of the SCG, and a SCell of an SCG may become an PSCell of the SCG, i.e., the PSCell and the SCell change roles in the SCG. There may be various reasons for performing a SpCell replacement operation. For example, the UE may be moving and may have a better connection with the SCell involved in the SpCell replacement operation, the SpCell involved in the SpCell replacement operation may have congestion problems, and so on. However, it should be understood that the exemplary embodiment is not specific to the reasons why the SpCell replacement operation occurs. Instead, the exemplary embodiment is intended to improve the SpCell replacement operation.

[0026] The exemplary embodiments are described with reference to UE. However, reference to UE is provided for illustrative purposes only. The exemplary embodiments may be used with any electronic component that can establish a connection with a network and is configured with hardware, software and / or firmware for exchanging information and data with the network. Therefore, the UE described herein is used to represent any electronic component.

[0027] The exemplary embodiments are also described with reference to 5G New Radio (NR) networks. However, it should be understood that the exemplary embodiments may also be implemented in other types of networks, including but not limited to LTE networks, future evolutions of cellular protocols, or any other type of network that assigns identifiers to devices that are using the network in an unsecured manner.

[0028] In the following exemplary embodiments, operations may describe various parameters or information elements (IEs) and assign names to these parameters or IEs. It should be understood that these names are exemplary only, and other names may be used to describe parameters or IEs that perform the same function.

[0029] Exemplary embodiments relate to various aspects of SpCell replacement. For example, in one aspect, the network may provide a common configuration for SCell and PSCell operations, and may provide a configuration for each identity that is specific to the operation of the serving cell (PSCell or SCell). As part of the replacement, this may include providing a common (e.g., cell-specific) configuration for non-PSCells to be applied by the UE without RRC signaling. This may further include the ability of the UE to apply the common and dedicated portions in the following situations: the common and dedicated portions are not released and added as part of L3 signaling (for SCell), and the network is not made aware that the SpCell common portion has been applied (for SpCell) when the network expects it. On the other hand, the network may provide incremental configuration on all of these different configurations.

[0030] In other aspects, the network may synchronize the change, for example, synchronizing the application time of the change between the network and the UE.In some aspects, there is no need to reset the data path because carrier aggregation (CA) already has all the required cells in both the source and the target.

[0031] In some aspects, certain unique CA situations are addressed. For example, in the case of asynchronous (Async) CA, the NW may derive and provide timing advance (TA) as part of the replacement, or skip TA adjustment / random access channel (RACH). As another example, in the case of frequency range 1 and frequency range 2 (FR1-FR2) CA, changing the serving FRx cell is the procedure for replacement. In yet another example, for the case of CA with different parameter sets, the handling of physical uplink control channel (PUCCH) timing is addressed. Other examples may include supplementary uplink (SUL) operations.

[0032] In some exemplary embodiments, the replacement may be part of a UE-initiated process, including a conditional UE-initiated replacement.Each of these exemplary embodiments and aspects will be described in more detail below.

[0033] Figure 1 An exemplary network arrangement 100 according to various exemplary embodiments is shown. The exemplary network arrangement 100 includes a UE 110. Those skilled in the art will appreciate that the UE 110 may be any type of electronic component configured to communicate via a network, such as a mobile phone, a tablet computer, a desktop computer, a smart phone, a phablet, an embedded device, a wearable device, an Internet of Things (IoT) device, etc. It should also be appreciated that an actual network arrangement may include any number of UEs used by any number of users. Therefore, the example of a single UE 110 is provided for illustrative purposes only.

[0034] UE 110 may be configured to communicate with one or more networks. In the example of network configuration 100, the network with which UE 110 may wirelessly communicate is a 5G NR radio access network (RAN) 120. However, it should be understood that UE 110 may also communicate with other types of networks (e.g., 5G cloud RAN, next generation RAN (NG-RAN), traditional cellular networks, etc.), and UE 110 may also communicate with the network via a wired connection. Referring to the exemplary embodiment, UE 110 may establish a connection with 5G NR RAN 120. Therefore, UE 110 may have a 5G NR chipset to communicate with NRRAN 120.

[0035] The 5G NR RAN 120 may be part of a cellular network that may be deployed by a network operator (e.g., Verizon, AT&T, T-Mobile, etc.). The RAN 120 may include cells or base stations that are configured to transmit and receive traffic from UEs equipped with appropriate cellular chipsets. In this example, the 5G NR RAN 120 includes gNB 120A and gNB 120B. However, reference to gNB is provided for illustrative purposes only, and any appropriate base station or cell (e.g., Node B, eNodeB, HeNB, eNB, gNB, gNodeB, macro cell, micro cell, small cell, femto cell, etc.) may be deployed.

[0036] Those skilled in the art will appreciate that any relevant process may be performed for UE 110 to connect to 5G NR RAN 120. For example, as described above, 5G NR RAN 120 may be associated with a particular network operator at which UE 110 and / or its user has protocol and credential information (e.g., stored on a SIM card). Upon detecting the presence of 5G NR RAN 120, UE 110 may send corresponding credential information in order to associate with 5G NR RAN 120. More specifically, UE 110 may be associated with a particular cell (e.g., gNB 120A or gNB 120B).

[0037] The network arrangement 100 also includes a cellular core network 130, the Internet 140, an IP multimedia subsystem (IMS) 150, and a network service backbone 160. The cellular core network 130 manages traffic flowing between the cellular network and the Internet 140. The IMS 150 can be generally described as an architecture for delivering multimedia services to the UE 110 using IP protocols. The IMS 150 can communicate with the cellular core network 130 and the Internet 140 to provide multimedia services to the UE 110. The network service backbone 160 communicates directly or indirectly with the Internet 140 and the cellular core network 130. The network service backbone 160 can be generally described as a collection of components (e.g., servers, network storage arrangements, etc.) that implement a set of services that can be used to extend the functionality of the UE 110 to communicate with various networks.

[0038] Figure 2 An exemplary UE 110 is shown according to various exemplary embodiments. The UE 110 will refer to Figure 1 100. UE 110 may represent any electronic device and may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. Other components 230 may include, for example, an audio input device, an audio output device, a battery providing a limited power source, a data acquisition device, a port for electrically connecting UE 110 to other electronic devices, a sensor for detecting the status of UE 110, and the like.

[0039] The processor 205 may be configured to execute multiple engines of the UE 110. For example, the engines may include a CA replacement engine 235 for performing operations including processing logic for common configuration of non-P(S) cells, network-provided incremental configuration, synchronous replacement, elimination of data path resets, and methods for addressing several unique CA situations. Each of these exemplary operations will be described in more detail below.

[0040] The above-described engine as an application (e.g., program) executed by the processor 205 is merely exemplary. The functionality associated with the engine may also be represented as a separate combined component of the UE 110, or may be a modular component coupled to the UE 110, such as an integrated circuit with or without firmware. For example, the integrated circuit may include an input circuit for receiving a signal and a processing circuit for processing the signal and other information. The engine may also be embodied as one application or multiple separate applications. In addition, in some UEs, the functionality described for the processor 205 is split between two or more processors (such as a baseband processor and an application processor). The exemplary embodiments may be implemented in any of these or other configurations of the UE.

[0041] Memory arrangement 210 may be a hardware component configured to store data related to operations performed by UE 110. Display device 215 may be a hardware component configured to display data to a user, and I / O device 220 may be a hardware component that enables a user to enter input. Display device 215 and I / O device 220 may be separate components or may be integrated together (such as a touch screen).

[0042] The transceiver 225 may be a hardware component configured to establish a connection with the 5G-NR RAN 120. Thus, the transceiver 225 may operate on a variety of different frequencies or channels (e.g., a continuous set of frequencies). For example, when configured, for example, NR-U, the transceiver 225 may operate on an unlicensed spectrum. The transceiver 225 includes a circuit configured to send and / or receive signals (e.g., control signals, data signals). Such signals may be encoded with information for implementing any of the methods described herein. The processor 205 may be operably coupled to the transceiver 225 and configured to receive signals from and / or send signals to the transceiver 225. The processor 205 may be configured to encode and / or decode signals (e.g., signaling from a base station of a network) for implementing any of the methods described herein.

[0043] Figure 3 An exemplary base station 300 is shown according to various exemplary embodiments. The base station 300 may represent a gNB 120A or a gNB 120B or any other access node through which the UE 110 may establish a connection and manage network operations. Those skilled in the art will understand that a base station may include multiple cells, for example, a gNB 120B may include a PCell and one or more SCells corresponding to the PCell, a PSCell and one or more SCells corresponding to the PSCell. On the other hand, gNB 120B may include one or more of these cells and other base stations (e.g., gNB 120A plus additional base stations) may include one or more of these cells. It should be understood that the exemplary embodiments may be implemented in any network configuration in which the SpCell may be replaced with an SCell.

[0044] The base station 300 may include a processor 305, a memory arrangement 310, an input / output (I / O) device 315, a transceiver 320, and other components 325. These other components 325 may include, for example, an audio input device, an audio output device, a battery, a data acquisition device, ports for electrically connecting the base station 300 to other electronic devices and / or a power source, and the like.

[0045] The processor 305 may be configured to execute multiple engines of the UE 110. For example, the engines may include a CA replacement engine 330 for performing operations including processing logic for common configuration of non-P(S) cells, network-provided incremental configuration, synchronous replacement, elimination of data path resets, and methods for addressing several unique CA situations. Each of these exemplary operations will be described in more detail below.

[0046] The memory 310 may be a hardware component configured to store data related to operations performed by the base station 300. The I / O device 315 may be a hardware component or port that enables a user to interact with the base station 300. The transceiver 320 may be a hardware component configured to exchange data with the UE 110 and any other UE in the network arrangement 100.

[0047] The transceiver 320 may operate on a variety of different frequencies or channels (e.g., a continuous frequency set). Therefore, the transceiver 320 may include one or more components (e.g., radio equipment) to enable data exchange with various networks and UEs. The transceiver 320 includes a circuit configured to send and / or receive signals (e.g., control signals, data signals). Such signals may be encoded with information for implementing any of the methods described herein. The processor 305 may be operably coupled to the transceiver 320 and configured to receive signals from the transceiver 320 and / or send signals to the transceiver. The processor 305 may be configured to encode and / or decode signals (e.g., signaling from a UE) for implementing any of the methods described herein.

[0048] There are several areas for improvement in SpCell to SCell handover operations. Exemplary embodiments relate to improved processing logic for common configuration of non-PSCells, network-provided incremental configuration, synchronous replacement, elimination of data path resets, and methods to address several unique CA situations.

[0049] However, before describing various exemplary embodiments, reference will be made to Figure 4 and Figure 5 Describes the general flow of operations for network-triggered SpCell replacement and UE-triggered SpCell replacement.

[0050] Figure 4 Depicted is a signaling diagram 400 of a network-triggered SpCell to SCell handover according to various exemplary embodiments. At 405, a UE (eg, UE 110) is in a connected state with a SpCell, but not operating in carrier aggregation (CA).

[0051] At 410, the SpCell transmits an RRC reconfiguration message to the UE 110 to start CA operation. The network adds SCell 1, SCell 2, and SCell 3. For each SCell configuration, SpCell parameters are provided to the UE 110. SCell operation and other parameters are also provided to the UE 110.

[0052] At 415, as part of the CA operation, UE 110 exchanges user data with SpCell and SCells 1 through 3. As will be appreciated by those skilled in the art, CA operation provides higher / faster data throughput than non-CA operation.

[0053] At 420, UE 110 transmits a measurement report to the SpCell via L2 or L3 signaling. The measurement report 420 is based on the network configuration. Based on the measurement report, the SpCell can determine whether a CA replacement is appropriate. In this example, it can be considered that the SpCell is being replaced with SCell 1, for example, the current SpCell will become the new SCell 1 and the current SCell 1 will become the new SpCell.

[0054] At 425, the current SpCell will transmit an L1 or L2 message indicating the change to the UE 110, for example, the current SpCell becomes the new SCell 1 and the current SCell 1 becomes the new SpCell. The L1 or L2 message may be a Medium Access Control-Control Element (MAC-CE) or Downlink Control Information (DCI).

[0055] At 430, UE 110 may transmit an optional random access channel (RACH) to the new SpCell (e.g., the previous SCell 1). For example, if the information element (IE) SPCell-operation-r18 in the SCell 1 configuration has ReconfigurationWithSync in which the IEapplicability L21-Handover bit is set, UE 110 will perform synchronous reconfiguration using RACH.

[0056] Therefore, after 430 (or 425), the previous SCell 1 is the current SpCell, and the previous SpCell is the current SCell 1. At 435, the UE 110 continues to operate in CA mode and exchanges data with SCell 1 acting as SPCell, SCell acting as SCell 1, and SCell 2 and SCell 3.

[0057] Figure 5A signaling diagram 500 is depicted for a UE-triggered SpCell to SCell handover according to various exemplary embodiments. 505 to 515 proceed in a manner substantially similar to 405 to 415 described above.

[0058] At 520, UE 110 evaluates conditional triggers for each of SCell 1, SCell 2, and SCell 3. When the triggering conditions are met, UE 110 selects the corresponding SCell to become the SpCell for CA. 525 and 530 are substantially similar to 430 and 435 described above, respectively. Some examples of conditional triggers are described below.

[0059] Thus, in signaling diagram 400, the network is the entity that determines that there should be a SpCell change based on measurement information provided by the UE.In signaling diagram 500, the UE is the entity that determines that there should be a SpCell change.

[0060] In a first aspect of an exemplary embodiment, a new configuration for CA replacement is disclosed. The new configuration includes additional information in the IE related to the CA configuration to facilitate CA replacement. As will be described in more detail below, a single RRC configuration can be used for multiple permutations and combinations of SpCells and SCells. Therefore, when the UE receives configuration information for a cell via RRC signaling, the configuration information may include information about when the cell operates as a SpCell or when the cell operates as a SCell. Therefore, when a CA replacement occurs, there is no RRC signaling overhead associated with the network transmitting RRC configurations to the UE for different roles of the cell, because the UE already includes a single RRC configuration associated with both the SpCell role and the SCell role. The SpCell role can be assigned to a serving cell in a candidate CA cell.

[0061] Those skilled in the art will appreciate that when UE 110 is in CA mode, the network will provide configuration information to UE 110 using, for example, RRC signaling, including configuration for SpCell and each of these SCells. In an exemplary embodiment, this configuration will include additional information that will facilitate SpCell replacement.

[0062] For example, for each SCell, the network may provide a potential SPCell configuration. In this case, when the network indicates that the SCell is to be treated as a SpCell, the UE 110 will apply the new configuration (e.g., the SpCell configuration provided in the RRC signaling for the SCell). Similarly, for each SpCell configuration, the network may provide a potential SCell configuration. The configuration may indicate that for any SpCell that is replaced to become an SCell, the UE 110 should apply the same configuration as provided for other SCells. In a variation of the first aspect of the exemplary embodiment, a separate SCell configuration for the SpCell may also be provided to the UE 110.

[0063] 6A depicts a first information element 600 for SpCell configuration in ASN.1 according to various exemplary embodiments. In this example, the IE SpCellConfig 600 includes additional information SCell-Operation 605. As described above, if the current SpCell is changed to become an SCell, the additional information 605 provides information about the cell configuration to the UE 110. Therefore, as described above, when receiving the IE 600 for this particular cell, the UE 110 understands the configuration of the cell when operating as a SpCell and when operating as an SCell, without providing further RRC configuration information to the UE 110. The UE 110 treats the additional information 605 as if the network provided the configuration as a separate RRC message. The UE 110 can apply it as an increment to the current active configuration.

[0064] 6B depicts a second information element 610 for SCell configuration in ASN.1 according to various exemplary embodiments. In this example, the IE SCellConfig 610 includes additional information spCell-Operation 615. As described above, if the current SCell is replaced to become a SpCell, the additional information 615 provides information about the cell configuration to the UE 110. Therefore, as described above, when receiving the IE 610 for the particular cell, the UE 110 understands the configuration of the cell when operating as a SpCell and when operating as a SCell, without providing further RRC configuration information to the UE 110. The UE 110 treats the additional information 615 as if the network provided the configuration as a separate RRC message. The UE 110 can apply it as an increment to the current active configuration. In addition, when the configuration changes, the UE 110 may not expect any release and addition of the current cell, for example, when the cell becomes a SpCell, the replacement does not require release and addition.

[0065] In a second aspect of the exemplary embodiment, a synchronization application is disclosed. If the SpCell common configuration is changed as part of a mobility event / handover, the common configuration is changed and replaced by the target cell common configuration. The change can be implemented using the ReconfigurationWithSync process. For example, in the above-mentioned first aspect, the spcell-operation IE can include reconfigurationWithSync.

[0066] However, since the timing advance (TA) does not change substantially between operating cells, there may be situations where no additional synchronization is required for the handover. For example, this situation may arise in smaller cell operation. This situation may also arise when the UE is already operating in CA and the target SpCell is already an existing SCell, and if the SCell already has UL, no additional synchronization is required as part of the handover. In this case, the upper layers will not be reset, potentially enabling an asynchronous handover. In the above case, when the handover is part of a CA change process, the network can instruct the UE that ReconFigurationWithSync does not need to be applied.

[0067] It should be noted that in asynchronous CA, the timing relationship and the corresponding need for synchronization may depend on the target cell (eg, target SpCell) or based on a combination of source and target cells in a CA configuration.

[0068] In a second aspect of the exemplary embodiment, a CA replacement configuration may be provided by the network to UE 110. Within the CA replacement configuration, when the SpCell configuration is applied to each SCell with a potential SpCell configuration (ie, candidate SCell), the network may indicate whether the UE should apply ReconfigWithSync(RACH).

[0069] In some exemplary embodiments, if UE 110 does not need to apply ReconfigWithSync, the network may indicate whether UE 110 should maintain the TA.

[0070] 7A depicts a first information element 700 in ASN.1, including information about whether synchronization during CA should be applied when a cell is changed to a SpCell, according to various exemplary embodiments. IE 700 includes parameter applicabilityL21-Handover 705. In a first example, if the bit string of this parameter is set to 1 for a particular serving cell, and if it is a handover from the serving cell to the current cell (the index value of the serving cell is the same as the position of the bit in the bit string), the UE 110 may apply the configuration in a synchronous manner as specified by the procedure with ReconfigurationWithSync. Conversely, if the bit is set to 0, the UE will understand that synchronization is not required when changing SpCells.

[0071] In this exemplary embodiment, the bit string may be arranged such that the first bit from the left in the bit string represents the serving cell with index 0, the next bit to the left represents the serving cell with index 1, etc. However, it should be understood that the bit string may be arranged in different ways to convey the same information.

[0072] 7B depicts a second information element in ASN.1 according to various exemplary embodiments, the second information element including information regarding whether synchronization during CA should be applied when a cell is changed to a SpCell. IE 700 includes a parameter applicabilityL21-Handover 715. In this example, the parameter may provide a list of serving cells. UE 110 may check whether the current cell being handed over to is from any serving cell on the list. If so, UE 110 applies the configuration in 710 in a synchronous manner specified by the procedure with ReconfigurationWithSync. On the other hand, if the serving cell is not on the list, UE 110 may perform the change without synchronization.

[0073] In terms of data path reset during the L2 / L1 handover process, a typical handover operation may result in radio link control (RLC) / medium access control (MAC) reestablishment and packet data convergence protocol (PDCP) recovery. However, when the source cell and the target cell belong to the same CA configuration, certain characteristics of the connection can be utilized without the need for a data path reset. Examples of these characteristics include that both the source cell and the target cell are within the same centralized unit (CU), which means that the security environment does not change. Not changing the CU also means that the PDCP anchor does not change. In another example, the RLC operates within a distributed unit (DU), which controls carriers from the same transmission / reception point. In some instances, a remote radio head (RRH) may also be used, but the RLC and MAC still reside in the same DU. In yet another example, a MAC reset may not be required because only the hybrid automatic repeat request (HARQ) process has the possibility of being reset as part of the CA replacement. However, in some exemplary embodiments, even the HARQ process does not need to be reset.

[0074] Therefore, in a third aspect of the exemplary embodiments, an improved data path reset logic is disclosed. In a first example of the third aspect, during a CA replacement operation, the UE 110 does not reset the data path without an explicit instruction from the network.

[0075] In a second example of the third aspect, the network may configure UE 110 according to whether a data path needs to be reset during a CA replacement operation. For example, in a first option, the network may configure a data path reset for CA replacement, where the SpCell and SCell perform a reset through a source cell or a target cell.

[0076] In a second option, the network may explicitly configure the RLC, MAC and / or PDCP actions required for the source and target cell alignment. In a third option, the reset logic may depend on a signaling radio bearer (SRB) or a data radio bearer (DRB).

[0077] Figure 8 An information element 800 for SpCell configuration in ASN.1 is depicted, including information related to data path reset during CA replacement, according to various exemplary embodiments. In a first example, IE 800 includes a parameter recoverPDCP 810. If this parameter is set (e.g., true), UE 110 will recover PDCP as part of the L2 / L1 replacement.

[0078] In a second example, IE 800 includes a parameter reestablishRLC 815. If this parameter is set (e.g., true), then as part of the L2 / L1 switch, UE 110 will reestablish RLC. In a third example, IE 800 includes a parameter resetMAC 820. If this parameter is set (e.g., true), then as part of the L2 / L1 switch, UE 110 will reset MAC.

[0079] In a fourth aspect of the exemplary embodiment, an improved SCell state logic is disclosed. If a particular SCell becomes a SpCell, then the existing network deployment may not allow SCell operation on a particular serving cell. In an exemplary embodiment, the network can control which SCells will be deactivated or reactivated after L2 / L1 handover.

[0080] In a first example of this fourth aspect, the network may configure UE 110 according to the SCell state after the SCell is replaced. In a first option, the network may configure UE 110 so that all SCells are deactivated after the CA replacement. In a second option, the network may explicitly configure a specific target cell of which SCell set is to be deactivated or activated after the replacement.

[0081] In a second example of the fourth aspect, L2 / L1 signaling may be used to inform UE 110 about which SCells will be activated / deactivated after the replacement. Figures 11 to 13 An example of L2 / L1 signaling is provided. It should be understood that the activation / deactivation information may be included in replacement configuration information included in any of the exemplary L2 / L1 signaling.

[0082] Fig. 9 An information element 900 for SpCell configuration in ASN.1 is depicted according to various exemplary embodiments, the information element including information related to the SCell activation state after CA replacement. IE 900 includes parameter scellActivationStatus 910. After handover, if the bit string has 1 for a particular serving cell, and the index value of the serving cell is the same as the position of the bit, then the UE 110 may activate the SCell when the bit is 1, and the UE may deactivate the SCell when the bit is 0. As described above, for other bit strings related to serving cell indexes, the first bit from the left may represent a serving cell with index 0, and the next leftmost bit represents a serving cell with index 1, and so on. However, the bit strings need not be arranged in this manner.

[0083] In a fifth aspect of the exemplary embodiment, various additional processing logics related to CA replacement are disclosed. For example, since there is no RRC reconfiguration as part of CA replacement, the serving cell ID cannot be changed. In existing methods, PCell always presents cell ID 0, while SCell and PSCell can have non-0 cell IDs. However, in the exemplary embodiment, the cell ID can be changed. These cell ID changes can be signaled to UE 110 by the network.

[0084] In the first example of the fifth aspect, the PCell ID may also be a non-zero value, and the SCell / PSCell may assume a zero value as the serving cell ID. In the second example, during a network-triggered CA change process, the UE 110 and the network may automatically change the two cell IDs so that the initial SpCell assumes the serving cell ID of the SCell that has now become the SpCell (and vice versa). The UE 110 may change the ID in all references (e.g., CSI configurations, where the reference transmission configuration indication identifier (TCI) or reference signal (RS) is from a cell whose serving cell is from the serving cell ID). As described above, the network may determine which of the two examples of the fifth aspect to use at a given time, and may signal the information to the UE 110.

[0085] In a sixth aspect of the exemplary embodiments, improved security for CA replacement is disclosed. The physical cell ID (PCI) can be used as a parameter to derive security keys. The UE 110 also uses the PCI when performing the reestablishment process. The PCI is also used to encrypt and ensure the integrity of the RRCConceptRestablishment when a radio link failure occurs in the cell where the UE 110 is currently residing. During the CA replacement process, the PCell will change dynamically, but the network should still be aware of the SpCell configuration. In these exemplary embodiments, it is assumed that the SpCell is the PCell, but this is not a requirement.

[0086] In a first example of the sixth aspect of the exemplary embodiment, the gNB-CU tracks the PCI of the PCell whenever the PCell changes. In the case where the UE 110 changes from a PCell whose PCI is "x" and there are multiple CA changes, the gNB-CU tracks the current PCI. If the UE 110 is handed over to a new cell (which is not itself part of the CA change), if there is a UE context request issued from another gNB-CU for the UE 110, the PCI of the cell from which the UE 110 changes is changed to the PCI used by the gNB-CU.

[0087] In a second example of the sixth aspect, when the UE 110 is in the inactive mode, the same logic as the first example may apply.

[0088] In a third example of the sixth aspect, in the presence of multiple CA change actions, the UE 110 may use the encryption / integrity input of the last operating PCell for the re-establishment process.

[0089] In a seventh aspect of the exemplary embodiment, improved network signaling of serving cell validity is disclosed. In the second aspect of the exemplary embodiment, it is assumed that the current set of serving cells will remain operational after the CA change. However, the network may inform the UE 110 which serving cells are valid and which serving cells are no longer applicable after the CA change.

[0090] In a first example of the seventh aspect, the network may notify the UE 110 of this information via explicit signaling. In a second example, this information may be based on the serving cell becoming the SpCell. In an option of the second example, information about which cells are valid may be provided as part of the MAC CE / L1 (L2 / L1 signaling). As described above, in Figures 11 to 13 An example L1 / L2 signaling structure is provided in, and this information may be included in the example signaling structure.

[0091] 10A depicts a first information element 1000 in ASN.1 that includes information related to the validity of serving cells after CA replacement according to various exemplary embodiments. Information element 1000 relates to the network providing explicit signaling to inform UE 110 which serving cells are valid and which serving cells are no longer applicable after CA replacement. Specifically, IE 1000 may include parameters sCellsToAddModList 1005 and sCellsToReleaseList 1010. These lists explicitly inform UE 110 which serving cells are valid and which serving cells are no longer applicable after CA replacement.

[0092] 10B depicts a second information element 1020 in ASN.1 according to various exemplary embodiments, the second information element including information related to the validity of the serving cell after CA replacement. Information element 1020 relates to the network providing information about which serving cells are valid and which serving cells are no longer applicable after CA replacement based on which serving cell becomes SpCell. Specifically, IE 1020 includes a parameter validServCells-L21-Handover 1025, which is a bit string corresponding to a serving cell index, indicating which serving cells are applicable (e.g., bits are set to 1) and which serving cells are no longer applicable (e.g., bits are set to 0) when a particular serving cell becomes SpCell.

[0093] Fig.11 A downlink (DL) downlink control information (DCI) L1 CA replacement structure 1100 is depicted according to various exemplary embodiments. The DL DCI CA replacement structure 1100 includes a DCI identifier field, a configuration index field, a UE-specific field, a bit string field, and a cyclic redundancy check (CRC) field. As described above, the DL DCI CA replacement structure 1100 can be used to signal various information for CA replacement to the UE 110 in L1 signaling. The examples provided above include which SCells will be activated / deactivated after the replacement, which serving cells are valid after the CA replacement, and which serving cells are no longer applicable. In these examples, the information can be conveyed in, for example, a bit string field. However, the information can be conveyed in other fields.

[0094] Fig.12 A first example medium access control-control element (MAC-CE) CA replacement structure 1200 is depicted in accordance with various exemplary embodiments. The MAC-CE CA replacement structure 1200 includes a MAC-CE type distinction field, a protected signature field, a configuration index field, and a servCellID field. As described above, the MAC-CE CA replacement structure 1200 can be used to signal various information for CA replacement to the UE 110 in L2 signaling. The examples provided above include which SCells will be activated / deactivated after the replacement, which serving cells are valid after the CA replacement, and which serving cells are no longer applicable. In these examples, this information can be conveyed in, for example, a separate servCellID field, such as setting a bit to 0 or 1 for a serving cell.

[0095] Fig.13A second example medium access control-control element (MAC-CE) CA replacement structure 1300 is depicted in accordance with various exemplary embodiments. The MAC-CE CA replacement structure 1300 includes a MAC-CE type distinction field, a protected signature field, a configuration index field, and a bit string field. As described above, the MAC-CE CA replacement structure 1300 can be used to signal various information for CA replacement to the UE 110 in L2 signaling. The examples provided above include which SCells will be activated / deactivated after the replacement, which serving cells are valid after the CA replacement, and which serving cells are no longer applicable. In these examples, the information can be conveyed in, for example, a bit string field, with a bit set to 0 or 1 for a serving cell index corresponding to a serving cell.

[0096] Example

[0097] In a first embodiment, a method performed by a base station includes: operating in a carrier aggregation (CA) mode with a user equipment (UE), wherein the base station operates as a special cell (SpCell) or at least one secondary cell (SCell) in the CA mode; performing a CA switching operation with the UE, the CA switching operation including at least one of the following: when the base station operates as the SpCell, the base station becomes a new SCell; or when the base station operates as the at least one SCell, the base station becomes a new SpCell.

[0098] In a second embodiment, the method according to the first embodiment further includes: receiving measurement data from the UE, determining that the measurement data indicates that the CA change operation should be performed, and transmitting a layer 1 (L1) or layer (L2) message to the UE indicating that the CA change operation should be performed.

[0099] In a third embodiment, the method according to the first embodiment further comprises: transmitting a SpCell configuration for the SpCell to the UE, wherein the SpCell configuration comprises a SCell configuration to be used by the UE for the CA change operation.

[0100] In a fourth embodiment, the method according to the first embodiment further comprises: transmitting a SCell configuration for the SCell to the UE, wherein the SCell configuration comprises a SpCell configuration to be used by the UE for the CA change operation.

[0101] In a fifth embodiment, the method according to the first embodiment further comprises: transmitting an SCell configuration for the SCell to the UE, wherein the SCell configuration comprises whether the UE should perform synchronization with the network when the SCell becomes the new SpCell during the CA change operation.

[0102] In a sixth embodiment, the method according to the fifth embodiment, wherein the synchronizing includes performing a random access channel (RACH) procedure with the network.

[0103] In a seventh embodiment, according to the method of the fifth embodiment, when the SCell configuration indicates that the synchronization will not be performed, the SCell configuration further includes information on whether the UE is to maintain a timing advance (TA) for the SCell.

[0104] In an eighth embodiment, the method according to the first embodiment further comprises: transmitting a configuration related to the CA replacement operation to the UE, wherein the configuration indicates a data path resetting operation to be performed when the CA replacement operation is performed.

[0105] In a ninth embodiment, the method according to the eighth embodiment, wherein the data path reset operation comprises one of a radio link control (RLC) operation, a medium access control (MAC) operation, or a packet data convergence protocol (PDCP) operation.

[0106] In a tenth embodiment, the method according to the eighth embodiment, wherein the configuration is provided for the SpCell or the SCell.

[0107] In an eleventh embodiment, according to the method of the eighth embodiment, the configuration indicates that the data path reset operation is specific to the SpCell and SCell pair involved in the CA replacement operation.

[0108] In a twelfth embodiment, according to the method of the eighth embodiment, the configuration indicates that the data path reset operation is specific to a signaling radio bearer (SRB) or a data radio bearer (DRB) between the UE and the new SpCell or between the UE and the new SCell.

[0109] In a thirteenth embodiment, the method according to the first embodiment further includes: transmitting to the UE information indicating whether to activate or deactivate the new SCell or one or more other SCells after the CA change operation.

[0110] In a fourteenth embodiment, according to the method of the thirteenth embodiment, the information indicates that all SCells are deactivated after the CA replacement operation.

[0111] In a fifteenth embodiment, the method of the thirteenth embodiment, wherein the information is specific to the new SpCell.

[0112] In a sixteenth embodiment, the method according to the thirteenth embodiment, wherein the information is transmitted in a layer 1 (L1) or layer (L2) message.

[0113] In a seventeenth embodiment, according to the method of the first embodiment, when the base station operates as the SpCell and the SpCell is a primary cell (PCell), a cell identity (cell ID) of the PCell is a non-zero value.

[0114] In an eighteenth embodiment, according to the method of the first embodiment, when the base station operates as the new SpCell or the new SCell, a cell identity (cell ID) of the new SpCell or the new SCell is a non-zero value.

[0115] In a nineteenth embodiment, according to the method of the first embodiment, wherein, when performing the CA replacement operation, the new SpCell is allocated with a cell identity (cell ID) of a previous SpCell, and the new SCell is allocated with a cell ID of a previous SCell.

[0116] In a twentieth embodiment, according to the method of the first embodiment, wherein the new SpCell is a primary cell (PCell), the operation further comprises: storing a physical cell identity (PCI) of the PCell in a control unit of the base station.

[0117] In a twenty-first embodiment, according to the method of the first embodiment, wherein the new SpCell is a primary cell (PCell), the operation further comprises: when the UE becomes an inactive mode, storing a PCI of the PCell.

[0118] In a twenty-second embodiment, according to the method described in the first embodiment, wherein the new SpCell is a primary cell (PCell), the operation further includes: performing a reconstruction process including one of encryption or integrity operations with the UE, wherein the UE uses the physical cell identifier (PCI) of the SpCell as input for the encryption or integrity operation.

[0119] In a twenty-third embodiment, the method according to the first embodiment further comprises: after the CA replacement operation, transmitting to the UE information indicating whether the new SCell or one or more other SCells are valid for the new SpCell.

[0120] In a twenty-fourth embodiment, the method of the twenty-third embodiment, wherein the information is specific to the new SpCell.

[0121] In a twenty-fifth embodiment, the method of the twenty-third embodiment, wherein the information is transmitted in a layer 1 (L1) or layer (L2) message.

[0122] In a twenty-sixth embodiment, a processor is configured to execute any of the methods according to the first to twenty-fifth embodiments.

[0123] In a thirteenth embodiment, a base station comprises: a transceiver configured to communicate with a user equipment (UE); and a processor communicatively coupled to the transceiver and configured to perform any of the methods described in the first to twenty-fifth embodiments.

[0124] Those skilled in the art will appreciate that the exemplary embodiments described above may be implemented with any suitable software configuration or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. In another example, the exemplary embodiments of the above method may be embodied as a program including lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, may be executed on a processor or microprocessor.

[0125] Although the present application describes various combinations of aspects each having different features, those skilled in the art will understand that any feature of one aspect may be combined with features of other aspects or features that are not functionally or logically inconsistent with the operation or function of the device of the aspects disclosed in the present invention in any manner not publicly denied.

[0126] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0127] It will be apparent to those skilled in the art that various modifications may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, it is intended that the present disclosure covers modifications and variations of the present disclosure as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A base station device, the device comprising a processing circuit, the processing circuit being configured to: operating in a carrier aggregation (CA) mode with a user equipment (UE), wherein the base station operates as a special cell (SpCell) or at least one secondary cell (SCell) in the CA mode; and performing a CA replacement operation with the UE, the CA replacement operation comprising at least one of the following: When the base station operates as the SpCell, the base station becomes a new SCell; or When the base station operates as the at least one SCell, the base station becomes a new SpCell.

2. The apparatus of claim 1 , wherein the processing circuit is further configured to: decoding measurement data based on a signal received from the UE; determining that the measurement data indicates that the CA replacement operation should be performed; and Transceiver circuitry is configured to transmit a layer 1 (L1) or layer (L2) message to the UE indicating that the CA change operation should be performed.

3. The apparatus of claim 1 , wherein the processing circuit is further configured to: Transceiver circuitry is configured to transmit a SpCell configuration for the SpCell to the UE, wherein the SpCell configuration includes an SCell configuration to be used by the UE for the CA change operation.

4. The apparatus of claim 1 , wherein the processing circuit is further configured to: Transceiver circuitry is configured to transmit an SCell configuration for the SCell to the UE, wherein the SCell configuration includes a SpCell configuration to be used by the UE for the CA change operation.

5. The apparatus of claim 1 , wherein the processing circuit is further configured to: Transceiver circuitry is configured to transmit an SCell configuration for the SCell to the UE, wherein the SCell configuration includes whether the UE should perform synchronization with the network when the SCell becomes the new SpCell during the CA change operation.

6. The apparatus of claim 5, wherein the synchronization comprises performing a random access channel (RACH) procedure with the network.

7. The device according to claim 5, wherein: When the SCell configuration indicates that the synchronization is not to be performed, the SCell configuration further includes information on whether the UE is to maintain a timing advance (TA) for the SCell.

8. The apparatus of claim 1, wherein the processing circuit is further configured to: The transceiver circuit is configured to transmit a configuration related to the CA replacement operation to the UE, wherein the configuration indicates a data path reset operation to be performed when the CA replacement operation is performed.

9. The apparatus of claim 8, wherein the data path reset operation comprises one of a radio link control (RLC) operation, a medium access control (MAC) operation, or a packet data convergence protocol (PDCP) operation.

10. The apparatus of claim 8, wherein the configuration is provided for the SpCell or the SCell.

11. The apparatus of claim 8, wherein the configuration indicates that the data path reset operation is specific to the SpCell and SCell pair involved in the CA replacement operation.

12. The apparatus of claim 8, wherein the configuration indicates that the data path reset operation is specific to a signaling radio bearer (SRB) or a data radio bearer (DRB) between the UE and the new SpCell or between the UE and the new SCell.

13. The apparatus of claim 1 , wherein the processing circuit is further configured to: Transceiver circuitry is configured to transmit information to the UE indicating whether to activate or deactivate the new SCell or one or more other SCells after the CA change operation.

14. The apparatus of claim 13, wherein the information indicates deactivation of all SCells after the CA change operation, wherein the information is specific to the new SpCell, and wherein the information is transmitted in a layer 1 (L1) or layer (L2) message.

15. The device according to claim 1, wherein: When the base station operates as the SpCell and the SpCell is a primary cell (PCell), a cell identifier (cell ID) of the PCell is a non-zero value.

16. The device according to claim 1, wherein When the base station operates as the new SpCell or the new SCell, a cell identifier (cell ID) of the new SpCell or the new SCell is a non-zero value.

17. The device according to claim 1, wherein: When the CA change operation is performed, the new SpCell is allocated with the cell identity (cell ID) of the previous SpCell, and the new SCell is allocated with the cell ID of the previous SCell.

18. The apparatus of claim 1, wherein the new SpCell is a primary cell (PCell), wherein the processing circuit is further configured to: A physical cell identity (PCI) of the PCell is stored in a control unit of the base station.

19. The apparatus of claim 1, wherein the new SpCell is a primary cell (PCell), wherein the processing circuit is further configured to: When the UE changes to the inactive mode, the PCI of the PCell is stored.

20. The apparatus of claim 1, wherein the new SpCell is a primary cell (PCell), wherein the processing circuit is further configured to: A reestablishment procedure including one of a ciphering or integrity operation is performed with the UE, wherein the UE uses a physical cell identity (PCI) of the SpCell as input for the ciphering or integrity operation.

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