Service cell change procedure with multiple candidate target cells

Abstract

Embodiments of this disclosure relate to apparatus, methods, devices, and computer-readable storage media utilizing a serving cell change process with multiple candidate target cells. The method includes receiving configuration information associated with a serving cell change process of a first device from a second device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that are available for the serving cell change process; executing a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell during the serving cell change process; and accessing a target cell determined from the first and second candidate cells after the serving cell change process is completed. In this way, the downtime corresponding to the CHO or CPC process when multiple candidates are available can be reduced.

Description

Technical Field

[0001] Embodiments of this disclosure generally relate to the telecommunications field, and more particularly to apparatus, methods, devices, and computer-readable storage media for a serving cell change process utilizing multiple candidate target cells. Background Technology

[0002] During a Conditional Handover (CHO) process, the source NR next-generation node B (gNB) can prepare one or more candidate target gNBs available for the CHO based on measurements performed at the user equipment (UE), and configure the UE for handover using up to two triggering conditions and the configuration of the prepared target cell. If a failure of the conditional HO to the first candidate target gNB that meets the conditions is detected, the UE is allowed to attempt an additional HO execution if a second candidate target gNB is available. The second CHO execution is performed sequentially and only after the first CHO execution fails. As a result, it may introduce delays in a successful handover, which could lead to radio link failures.

[0003] To reduce downtime associated with handovers in the downlink (DL) and uplink (UL), a Dual Active Protocol Stack (DAPS) solution has been introduced. Each of the source and target cells has a complete L2 protocol stack with its own security keys for encrypting and decrypting Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs). To avoid hard handovers that would cause service disruptions, the UE should establish a new radio link with the target cell before disconnecting the source cell's radio link. That is, the UE can exchange data with both the source and target nodes before the source cell is released. In DAPS, when random access to the target cell is complete, the UE can hand over the UL user plane (transmission of the new PDCP SDU) to the target cell. All other UL signaling (e.g., CSI feedback, PDCP status reports, HARQ feedback) continues between the UE and the source cell until it is released.

[0004] During Conditional PSCell Change (CPC), after receiving measurement results from the UE, the source primary / secondary cell (PSCell) can prepare one or more target PSCells in the secondary node (SN) and provide the UE with the CPC execution conditions and the configuration of the prepared target PSCells. Once the CPC execution conditions are met at the UE, the UE detaches from the source PSCell and performs access to the new target PSCell. If the CPC command is configured via Signaling Radio Bearer 1 (SRB1), the UE needs to send an RRC reconfiguration complete message to the primary node (MN) when the CPC execution conditions are met. If the CPC command is received via SRB3 of the SN, this is not required. Whether the UE continues to measure the candidate PScell ​​configured as an execution condition in the event of CPC failure is determined by the UE implementation. When an RLF or HOF of a PSCell is detected, an S-RLF is detected, and the UE sends a secondary cell group (SCG) failure information to the MN. During CPC, the source NR next-generation NodeB (gNB) secondary PCell can prepare one or more candidate target gNBs available for CPC based on measurements performed at the user equipment (UE), and configure the UE for PSCell changes using triggering conditions and the configuration of the prepared target cells.

[0005] Multiple USIM devices can support two (dual) or more (multi) simultaneous network subscriptions. MUSIM devices are widely available in the market, particularly in the enhanced mobile broadband (eMBB) segment. These devices may have limited hardware resources and must share the same resources at the UE. Therefore, the hardware of multiple USIM devices can be reused to support services on two or more networks simultaneously. A MUSIM device can form a small gap in its RRC_connection with one subscription to support services on another subscription. This interruption can be coordinated with the network. Summary of the Invention

[0006] Overall, the exemplary embodiments of this disclosure provide a solution for enhancing the CHO process or CPC process using multiple candidate target cells.

[0007] In a first aspect, a first device is provided. The first device 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 together with the at least one processor to cause the first device to at least: receive configuration information associated with a serving cell change process of the first device from a second device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; execute a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell during the serving cell change process; and access a target cell determined from the first candidate cell and the second candidate cell after the serving cell change process is completed.

[0008] In a second aspect, a method is provided. The method includes receiving configuration information from a second device associated with a serving cell change process of a first device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; during the serving cell change process, performing a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell; and after the serving cell change process is completed, accessing a target cell determined from the first and second candidate cells.

[0009] In a third aspect, an apparatus is provided, comprising: components for receiving configuration information associated with a serving cell change process of a first device from a second device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; components for performing a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell during the serving cell change process; and components for accessing a target cell determined from the first and second candidate cells after the serving cell change process is completed.

[0010] In a fourth aspect, a computer-readable medium having a computer program stored thereon is provided, which, when executed by at least one processor of the device, causes the device to perform the method according to the second aspect.

[0011] Other features and advantages of the embodiments of this disclosure will also become apparent from the following detailed description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate the principles of the embodiments of this disclosure by way of example. Attached Figure Description

[0012] The embodiments disclosed herein are presented in an exemplary sense, and their advantages will be explained in more detail below with reference to the accompanying drawings, in which...

[0013] Figure 1 An example environment in which example embodiments of this disclosure may be implemented is shown;

[0014] Figure 2 A signaling diagram illustrating a serving cell change process for conditional handover using multiple candidate target cells according to some example embodiments of the present disclosure is shown.

[0015] Figure 3 A signaling diagram illustrating a serving cell change process using multiple candidate target cells to perform conditional PSCell change according to some example embodiments of the present disclosure is shown.

[0016] Figure 4 Examples of time-division multiplexing (TDM) modes according to some exemplary embodiments of this disclosure are shown;

[0017] Figure 5 A flowchart is shown of an example method for determining the relative phase for frequency drift compensation according to some example embodiments of the present disclosure;

[0018] Figure 6 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and

[0019] Figure 7 A block diagram of an example computer-readable medium according to some embodiments of the present disclosure is shown.

[0020] Throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0021] The principles of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described merely for illustration and to help those skilled in the art understand and implement this disclosure, and do not imply any limitation on the scope of this disclosure. The disclosure described herein can be implemented in various other ways besides those described below.

[0022] In the following description and claims, unless otherwise defined, 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 pertains.

[0023] In this disclosure, references to "an embodiment," "embodiment," and "example embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, those skilled in the art will understand that, whether explicitly described or not, combining it with other embodiments to affect such a feature, structure, or characteristic is within the knowledge of those skilled in the art.

[0024] It should be understood that although the terms “first” and “second”, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish the functions of various elements. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. The singular forms “a,” “an,” and “the” used herein also include the plural forms unless the context clearly indicates otherwise. Further understanding, the terms “comprises,” “comprising,” “has,” “having,” “includes,” and / or “including” as used herein specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0026] As used in this application, the term "circuit system" may refer to one or more or all of the following:

[0027] (a) Pure hardware circuit implementation (such as implementation using only analog and / or digital circuit systems), and

[0028] (b) A combination of hardware circuitry and software, such as (if applicable):

[0029] (i) A combination of (multiple) analog and / or digital hardware circuits and software / firmware, and

[0030] (ii) Any part of a hardware processor(s) having software (including (multiple) digital signal processors), software, and (multiple) memories, which work together to cause a device (such as a mobile phone or server) to perform various functions, and

[0031] (c) Multiple hardware circuits and / or multiple processors, such as multiple microprocessors or a portion thereof, that require software (e.g., firmware).

[0032] The software can be used to perform operations, but can be left unused when no operation is needed.

[0033] The definition of "circuit system" applies to all uses of the term in this application, including in any claim. As another example, as used in this application, the term "circuit system" also covers implementations of only hardware circuitry or processors (or processors in general) or portions thereof and their accompanying software and / or firmware. For instance, if applicable to a particular claim element, the term "circuit system" also covers baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or network devices.

[0034] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as fifth-generation (5G) systems, Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in a communication network can be performed according to any suitable generation communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, future fifth-generation (5G) New Radio (NR) communication protocols, and / or any other currently known or future protocols. Embodiments of this disclosure can be applied to various communication systems. Given the rapid development of communications, future types of communication technologies and systems may also embody this disclosure. The scope of this disclosure should not be limited to the systems described above.

[0035] As used herein, the term "network device" refers to a node in a communication network through which terminal devices access the network and receive services. A network device can refer to a base station (BS) or access point (AP), such as a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), an NR next-generation Node B (gNB), a remote radio unit (RRU), a radio header (RH), a remote radio headend (RRH), a relay, a low-power node (such as a femtosecond or picosecond), etc., depending on the terminology and technology applied. The RAN split architecture includes a gNB-CU (centralized unit, which hosts RRC, SDAP, and PDCP) that controls multiple gNB-DUs (distributed units, which host RLC, MAC, and PHY). A relay node may correspond to the DU portion of an IAB node.

[0036] The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices can include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEE), laptop in-vehicle devices (LME), USB dongles, smart devices, wireless customer premises equipment (CPE), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Terminal equipment may also correspond to the mobile termination (MT) portion of an integrated access and backhaul (IAB) node (also known as a relay node). In the following description, the terms "terminal equipment," "communication equipment," "terminal," "user equipment," and "UE" are used interchangeably.

[0037] While the functions described herein may be implemented in fixed and / or wireless network nodes in various exemplary embodiments, in other exemplary embodiments, the functions may be implemented in a user equipment device (such as a mobile phone, tablet, laptop, desktop computer, mobile IoT device, or fixed IoT device). For example, the user equipment device may be suitably equipped with corresponding capabilities as described in combination with (multiple) fixed and / or wireless network nodes. The user equipment device may be a user equipment and / or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functions include boot server functions and / or home subscriber servers, which may be implemented in the user equipment device by providing software configured to cause the user equipment device to perform from the perspective of these functions / nodes.

[0038] Figure 1 An example communication network 100 in which embodiments of the present disclosure may be implemented is shown. Figure 1 As shown, the communication network 100 includes a terminal device 110 (hereinafter also referred to as the first device 110 or UE 110) and a network device 120 (hereinafter also referred to as the second device 120 or source gNB). The terminal device 110 can communicate with the network device 120.

[0039] The communication network 100 may further include network devices 130 and 140. Network devices 130 and 140 can be considered neighboring gNBs of network device 120. Network device 120 can communicate with network devices 130 and 140. For the CHO procedure of terminal device 110, network device 120 can at least prepare network devices 130 and 140 and receive configuration from network devices 130 and 140. Then, network device 120 can provide configuration information for the CHO procedure, which at least indicates network devices 130 and 140 as candidate target gNBs for the CHO procedure. When the CHO conditions are met, terminal device 110 can attempt to access one of the candidate target cells of network device 130 and network device 140, and disconnect from network device 120. Therefore, in the following text, network device 130 may also be referred to as the first candidate target gNB 130, and network device 140 may also be referred to as the second candidate target gNB 140.

[0040] In an NR SN scenario, terminal device 110 may include a primary node (MN) UE and a secondary node (SN) UE. Figure 1 (Not shown in the image). Network device 120 may include a PSCell, and the SN UE may access the PSCell. The PSCell managed by network device 120 may be referred to as source PSCell 120. For the CPC procedure, source PSCell 120 may prepare at least target PSCells 130 and 140, and receive configuration from target PSCells 130 and 140. Then, source PSCell 120 may provide configuration information for the CPC procedure, which at least indicates target PSCells 130 and 140 as candidate target gNBs for the CHO procedure. Therefore, in the following text, network device 130 may also be referred to as first candidate target PSCell 130, and network device 140 may also be referred to as second candidate target PSCell 140.

[0041] It should be understood that Figure 1 The number of network devices and terminal devices shown is given for illustrative purposes and does not impose any limitations. Communication network 100 may include any suitable number of network devices and terminal devices.

[0042] Depending on the communication technology, network 100 can be a Code Division Multiple Access (CDMA) network, Time Division Multiple Access (TDMA) network, Frequency Division Multiple Access (FDMA) network, Orthogonal Frequency Division Multiple Access (OFDMA) network, Single Carrier Frequency Division Multiple Access (SC-FDMA) network, or any other network. The communications discussed in network 100 can conform to any suitable standard, including but not limited to New Radio Access (NR), Long Term Evolution (LTE), LTE Evolution, LTE-A Advanced, Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for Mobile Communications (GSM). Furthermore, communications can be performed according to any generation of communication protocols currently known or to be developed in the future. Examples of communication protocols include, but are not limited to, first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, and fifth-generation (5G) communication protocols. The technologies described herein can be used in the aforementioned wireless networks and radio technologies, as well as other wireless networks and radio technologies. For clarity, some aspects of these technologies are described below in relation to LTE, and the terminology of LTE is used in most of the following description.

[0043] Typically, for CHO or CPC, the source cell (i.e., PCell or PSCell) can identify one or more suitable neighboring cells as candidate target PCells / PCells. The source cell can prepare multiple target cells and configure the UE for CHO or CPC; that is, more than one CHO or CPC condition can be configured for the UE via the gNB.

[0044] If more than one target PCell is prepared for CHO or more than one target PScell ​​is prepared for CPC, and both conditions are met, then in the normal manner, the UE can separate from the source cell and initiate CHO / CPC execution to the first candidate target cell. Only if the CHO / CPC execution initiated to the first candidate target cell fails can the UE attempt to execute to the second candidate cell. Therefore, the interruption time is prolonged due to the execution of subsequent access to another prepared target cell.

[0045] Therefore, this disclosure proposes a solution for the serving cell change process utilizing multiple candidate target cells. In this solution, when the conditions for handover or PSCell change are met and the UE is configured with multiple candidate target cells available for the handover or PSCell change process, the UE can initiate a random access procedure to at least two candidate target cells and complete access to only one of them. In this way, the downtime corresponding to the CHO or CPC procedure can be reduced in the event of access failure to the first target candidate and when multiple candidates are available.

[0046] The following will be referenced Figures 2-5 The principles and implementation of this disclosure are described in detail. Figure 2 A signaling diagram illustrating a conditional handover process utilizing multiple candidate target cells according to some example embodiments of the present disclosure is shown. Process 200 may involve UE 110, source gNB 120, first candidate target gNB 130, and second candidate target gNB 140. For discussion purposes, reference will be made to... Figure 1 Describe the process 200.

[0047] like Figure 2 As shown, UE 110 can perform measurements based on the measurement configuration configured by source gNB 120, and periodically or when a trigger for reporting a measurement report is met, transmits a measurement report to source gNB 120. Based on the measurement report from UE 110, source gNB can determine one or more candidate target gNBs for the handover process of UE 110.

[0048] For example, the source gNB 120 can transmit a handover request (206) to the first candidate target gNB 130, which can then prepare a candidate target cell for UE 110 to access. Similarly, the source gNB 120 can transmit a handover request (208) to the second candidate target gNB 140, which can then prepare another candidate target cell for UE 110 to access. Correspondingly, the first and second candidate target gNBs can configure relevant admission control information for the handover request and transmit a handover confirmation to the source gNB 120.

[0049] The source gNB 120 can obtain configuration information associated with the handover process of UE 110 from the candidate target gNB. The configuration information may indicate at least the candidate target cells provided by the first candidate target gNB 130 and additional candidate target cells provided by the second candidate target gNB 140. The source gNB 120 can also configure the UE against the HO using up to two trigger conditions and the configuration information of the candidate target cells prepared for UE 110. Then, the source gNB 120 can transmit the configuration information and trigger conditions to UE 110.

[0050] If the UE 110 determines that the triggering conditions for the first candidate target cell (i.e., the candidate target cell provided by the first candidate target gNB 130) are met, then the UE 110 can detach from the source gNB 212. Furthermore, the UE 110 can initiate a first random access procedure for accessing the first candidate target cell based on its configuration. To initiate the first random access procedure, the UE 110 can transmit a random access channel (RACH) preamble 214 to the first candidate target gNB 130.

[0051] If UE 110 determines that the triggering conditions for the second candidate target cell (i.e., the candidate target cell provided by the second candidate target gNB 140) are met, UE 110 can also create a second PS instance 216 with the configuration of the second candidate target cell, and initiate a second random access procedure for accessing the second candidate target cell based on this configuration. In order to initiate the second random access procedure, UE 110 can transmit a 218RACH preamble to the second candidate target gNB 140.

[0052] In some example embodiments, if the triggering conditions of the second candidate target cell are met, the second random access procedure can be initiated at the same time as the first random access procedure.

[0053] As an example embodiment, the second random access procedure can also be initiated after a predefined time interval. For example, after the first random access procedure is initiated, a timer will start. The duration T of this timer is less than the duration of timer T304 for handover failure. If UE 110 does not receive a random access response (RAR) for the first random access procedure (first or nth RACH attempt) when timer T expires, the second random access procedure can be initiated immediately.

[0054] If the RAR of the first random access procedure is not received by UE 110 and the RAR of the second random access procedure has been received by UE 110, then UE 110 can access the second candidate target cell.

[0055] For example, such as Figure 2 As shown, if UE 110 receives the RAR of the first random access procedure 220, UE 110 can access the first candidate target cell. Then, UE 110 can release the initiated second random access procedure. For example, when UE 110 receives the RAR of the first random access procedure, UE 110 can stop the second random access procedure for the second candidate target cell. Once successful access to the first candidate target cell is achieved, the source gNB 120 will cancel the CHO preparation at the second candidate target gNB 140.

[0056] For example, such as Figure 2 As shown, if UE 110 also receives the RAR of the second random access procedure 222, the UE can determine the resources to be granted to UE 110 based on the RAR, and transmit a message 224 for releasing the second random access procedure, such as the message "Release-config", to the second candidate target gNB 140 via the granted resources.

[0057] The second candidate target gNB 140 can release the prepared configuration after receiving the message "Release-config". In some example embodiments, the second candidate target gNB 140 can also release the prepared configuration if no response is received from the UE within a predefined time interval.

[0058] If the RAR of the second random access procedure is not received by UE 110 within a predefined time interval, UE 110 may also release the initiated second random access procedure.

[0059] After the second random access procedure is released, UE 110 can release the second PS instance created in 226 and transmit message 228 "RRC reconfiguration complete" to the first candidate target gNB 140.

[0060] In some example embodiments, if UE 110 is a single RX / TX device, resources can be time-multiplexed across the first random access procedure and the second random access procedure.

[0061] For example, in the case of a synchronization candidate target gNB, UE 110's TDM mode can be negotiated with the network. That is, UE 110 can use TDM mode to initiate the first random access procedure and the second random access procedure.

[0062] Alternatively, UE 110 may not apply the full configuration of the candidate target cell. For example, UE 110 can use RACH configurations from both the first and second candidate target cells to initiate RACH access only. Then, UE 110 can apply the full configuration of the candidate target cell that first completes RACH access. If there is a problem when applying the partial RRC reconfiguration message (i.e., the RACH portion) / full RRC reconfiguration message (including higher layers), the UE needs to trigger a re-establishment. This problem can be avoided if the full configuration is verified beforehand.

[0063] As described above, the solution proposed in this disclosure can also be used in CPC processes. Figure 3 A signaling diagram illustrating process 300, which demonstrates a PSCell change process utilizing multiple candidate target cells according to some example embodiments of the present disclosure, is shown. Process 300 may involve UE 110, which may include MN UE 110-1 and SN UE 110-2, source PSCell 120, first candidate target PSCell 130, and second candidate target PSCell 140. For purposes of discussion, reference will be made to... Figure 1 Describe the process 300.

[0064] Based on existing MUSIM operation mechanisms, MN UE 110-1 can transmit a 301 message "UE assistance information" to MN PCell 160. The corresponding serving cell in MN (PCell) 160 and MN UE 110-1 may have already agreed on a communication gap (start / stop or predefined duration). Alternatively, MN UE 110-1 can negotiate a 301 TDM mode with the network. When the configured gap or TDM mode is enabled, it can define the UE availability multiplexed between MN service and another communication with a different cell.

[0065] like Figure 3 As shown, UE 110 can perform measurements based on the measurement configuration configured by source PSCell 120, and periodically or when a trigger for reporting measurement reports is met, 302 transmits measurement reports to source PSCell 120. Based on the measurement reports from UE 110, source PSCell can determine 304 one or more candidate target PSCells for the CPC procedure of UE 110.

[0066] For example, source PSCell 120 can transmit 306, such as a request for SN addition, to first candidate target PSCell 130. The target PSCell can be in the same or a different SN. Furthermore, in the example shown in the figure, this request is transmitted from the source PSCell, but it could also be directed via MN / PCell 160. Source PSCell 120 can also transmit 308, such as a handover request and admission control information, to second candidate target PSCell 140. Accordingly, first candidate target PSCell 130 and second candidate target PSCell 140 can also transmit, such as a handover confirmation, to source PSCell 120.

[0067] The source PSCell 120 can obtain configuration information associated with the CPC procedure of UE 110 from the candidate target PSCell. The configuration information can indicate at least candidate target PSCell 130 and another candidate target PSCell 140. The source gNB 120 can also configure the UE based on PSCell changes and the configuration information of the candidate target PSCells prepared for UE 110. Then, the source PSCell 120 can transmit configuration information and triggering conditions to UE 110.

[0068] If UE 110 determines that the triggering conditions of the first candidate target PSCell are met, UE 110 can separate from the source PSCell 312 and initiate a first random access procedure to access the first candidate target PSCell using the resources of SN UE 110-2. In order to initiate the first random access procedure, UE 110 may transmit a 314 random access channel (RACH) preamble to the first candidate target PSCell 130.

[0069] If UE 110 determines that the triggering conditions for the second candidate target PSCell are met, UE 110 can request resources from MN UE110-1 and initiate a second random access procedure to access the second candidate target PSCell using the requested resources. Before the second random access procedure is initiated, MN UE 110-1 can request 317 that its MN PCell 160 suspend its activity. To initiate the second random access procedure, UE 110 can transmit a 318RACH preamble to the second candidate target PSCell 140.

[0070] In some example embodiments, if the triggering condition of the second candidate target PSCell is met, the second random access procedure can be initiated at the same time as the first random access procedure.

[0071] As an example embodiment, the second random access procedure can also be initiated after a predefined time interval. For example, after the first random access procedure is initiated, a timer will start. The duration T of this timer is less than the duration of timer T304 for handover failure. If UE 110 does not receive a random access response (RAR) for the first random access procedure (first or nth RACH attempt) when timer T expires, the second random access procedure can be initiated immediately.

[0072] If the RAR of the first random access procedure is not received by UE 110 and the RAR of the second random access procedure has been received by UE 110, then UE 110 can access the second candidate target PSCell.

[0073] For example, such as Figure 3 As shown, if UE 110 receives the RAR of the first random access procedure (320), UE 110 can access the first candidate target PSCell. Then, UE 110 can release the initiated second random access procedure. For example, when UE 110 receives the RAR of the first random access procedure, UE 110 can stop the second random access procedure for the second candidate target cell. Once successful access to the first candidate target PSCell 130 is achieved, the source PSCell 120 will cancel the CPC preparation at the second candidate target PSCell 140.

[0074] For example, such as Figure 3 As shown, if UE 110 also receives the RAR of the second random access procedure 322, the UE can determine the resources to be granted to UE 110 based on the RAR, and transmit the message 324 for releasing the second random access procedure, for example, the message "Release-config", to the second candidate target PSCell 140 via the granted resources.

[0075] The second candidate target PSCell 140 can release the prepared configuration after receiving the message "Release-config". In some example embodiments, the second candidate target PSCell 140 can also release the prepared configuration if no response is received from the UE within a predefined time interval.

[0076] If the RAR of the second random access procedure is not received by UE 110 within a predefined time interval, UE 110 may also release the initiated second random access procedure.

[0077] After the second random access procedure is released, the UE can restore its connection to MN PCell 160 (325) and transmit message (326) "RRC reconfiguration complete" to the first candidate target gNB 140.

[0078] In some example implementations, when the UE's hardware and PS resources are shared across two connections, for example, when shared between the RACH access procedures of the MN and SN to access the target PSCell, a TDM mode can be applied to reuse resources. Figure 4 Examples of TDM modes according to some exemplary embodiments of this disclosure are shown. For example... Figure 4 As shown, for example, during time intervals 410, 430, and 450, the MN UE resource can serve the MCG, while during time intervals 420 and 440, the MN UE resource can serve the PSCell.

[0079] For example, TDM mode can be configured in coordination with the network. The network can configure TDM mode for MCG tributaries. Figure 3 As shown, the UE can use TDM mode to access the second candidate target PSCell only during the time when it needs to access the second candidate target PSCell via the resources of the MN UE.

[0080] During CPC preparation, the TDM mode may need to be passed to the candidate target PSCell to align the timing between the PCell and the candidate target PSCell when it is enabled for RACH access. For example, when the UE begins RACH access to a second candidate target PSCell, the UE can request the PCell to activate the TDM mode in the PCell. Once RACH access to the target PSCell is complete, the UE can request the PCell to deactivate the TDM mode. The PCell can reject the UE's request to activate or deactivate the TDM mode during MN UE Resource Service Critical MCG activities.

[0081] Alternatively, similar to TDM mode, gaps can be configured in coordination with the network. The network can allow the UE to initiate autonomous gaps, i.e., gap start / end instead of a predefined pattern. The UE can notify the PCell when a gap is desired (e.g., a gap start flag). The network can suspend the PCell and start a timer associated with the gap. The UE can also start a timer and reconfigure its MN resources for RACH access to a candidate target PSCell. A gap can end when the UE notifies that the gap is ending or when the timer expires. The network can also refuse gap initiation.

[0082] As an alternative, a discontinuous reception (DRX) method can also be configured. During each DRX cycle, the UE can monitor the PDCCH for any PDSCH or CG and transmit its UL control and data. When all DL / UL control and scheduling traffic is complete, it starts an inactivity timer and enters a sleep state after the timer expires. For example, the UE can apply its sleep time in the MN to RACH access to a second candidate target PSCell. In this case, DRX can only be enabled if indicated by an additional indication in the DRX configuration that it is needed.

[0083] In this way, for both the CHO and CPC processes, when multiple candidates are available, downtime can be reduced.

[0084] Figure 5 A flowchart illustrating an example method 500 for serving cell changing using multiple candidate target cells according to some example embodiments of the present disclosure is shown. Method 500 can be implemented as follows: Figure 1 The first device 110 shown is implemented here. For the purposes of discussion, reference will be made to... Figure 1 Description method 500.

[0085] At 510, the first device receives configuration information from the second device associated with the first device's serving cell change process. The configuration information at least indicates a first candidate target cell managed by the third device and a second candidate target cell managed by the fourth device that can be used in the above process.

[0086] At 520, during the serving cell change process, the first device executes a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell.

[0087] In some example embodiments, the first device may perform both the first random access procedure and the second random access procedure simultaneously.

[0088] In some example embodiments, the first device may determine whether a first random access response of a first random access procedure was received by the first device within a first time interval, the first time interval being shorter than a second time interval configured by the second device to indicate failures in the serving cell change process. If the first device determines that the first random access response was not received within the first time interval, the first device may execute a second random access procedure.

[0089] At 530, after the serving cell change process is completed, the first device accesses the target cell determined from the first candidate target cell and the second candidate target cell.

[0090] In some example embodiments, if the first device determines that the first random access response of the first random access procedure has not been received by the first device and the second random access response of the second random access procedure has been received by the first device, then the first device can complete the access to the second candidate cell.

[0091] In some example embodiments, if the first device determines that both the first random access response of the first random access procedure and the second random access response of the second random access procedure have been received by the first device and the first candidate cell has been selected as the target cell, then the first device can complete the access to the first candidate cell.

[0092] In some example embodiments, if the first device determines that it will be accessed by the first candidate cell, the first device may release the second random access procedure.

[0093] In some example embodiments, if the first device determines that the first random access response to the first random access procedure has been received by the first device, the first device may release the second random access procedure.

[0094] In some example embodiments, if the first device determines that the second random access response of the second random access procedure has been received by the first device, the first device can determine the resources granted to the first device from the second random access response, and transmit a message for releasing the second random access procedure to the fourth device via the resources.

[0095] In some example embodiments, the first device may determine whether the second random access response of the second random access procedure was received by the first device within a third time interval configured for the first device to receive the second random access response. If the first device determines that the second message was not received within the third time interval, the first device may release the second random access procedure.

[0096] In some example embodiments, the first device includes a terminal device, the second device includes a network device, the third device includes a network device, and the fourth device includes a network device.

[0097] In some example embodiments, an apparatus capable of performing method 500 (e.g., implemented at the first device 110) may include components for performing corresponding steps of method 500. These components may be implemented in any suitable form. For example, the components may be implemented in a circuit system or a software module.

[0098] In some example embodiments, the apparatus includes components for receiving configuration information associated with a serving cell change process of the first device from a second device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; components for performing a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell during the serving cell change process; and components for accessing a target cell determined from the first and second candidate cells after the serving cell change process is completed.

[0099] Figure 6 This is a simplified block diagram of a device 600 suitable for implementing embodiments of the present disclosure. The device 600 can be provided to implement a communication device, such as... Figure 1 The terminal device 110 is shown. As shown, device 600 includes one or more processors 610, one or more memories 620 coupled to processor 610, and one or more transmitters and receivers (TX / RX) 640 coupled to processor 610.

[0100] The TX / RX 640 is used for bidirectional communication. The TX / RX 640 has at least one antenna to facilitate communication. The communication interface can represent any interface required for communication with other network components.

[0101] Processor 610 can be any type suitable for a local technology network, and by way of non-limiting example, can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Device 600 can have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock synchronized with the main processor.

[0102] Memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 624, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disk (DVD), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 622 and other volatile memories that do not persist during power outages.

[0103] Computer program 630 includes computer-executable instructions that are executed by the associated processor 610. Program 630 may be stored in ROM 620. Processor 610 can perform any suitable actions and processes by loading program 630 into RAM 620.

[0104] The embodiments of this disclosure can be implemented via program 630, enabling device 600 to execute reference... Figures 2 to 5 Any process discussed in this disclosure. Embodiments of this disclosure may also be implemented by hardware or a combination of software and hardware.

[0105] In some embodiments, program 630 may be tangibly contained in a computer-readable medium, which may be included in device 600 (such as memory 620) or other storage device accessible to device 600. Device 600 may load program 630 from the computer-readable medium into RAM 622 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Figure 7 An example of a computer-readable medium 700 in the form of a CD or DVD is shown. A program 630 is stored on the computer-readable medium.

[0106] Generally, the various embodiments of this disclosure can be implemented using hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented using hardware, while others can be implemented using firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein can be implemented using hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0107] This 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 instructions included in a program module, which execute in a device on a target real or virtual processor to perform the above-referenced... Figure 5 Method 500 is described. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of a program module can be combined or split among program modules as needed. The machine-executable instructions of a program module can be executed on a local or distributed device. In a distributed device, a program module can reside on both local and remote storage media.

[0108] Program code used to perform the methods of this disclosure may be written in any combination of one or more programming languages. This 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 when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a stand-alone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0109] In the context of this disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0110] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any suitable combination thereof. More specific examples of computer-readable storage media will include electrical connections having one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0111] Furthermore, although operations are described in a specific order, this should not be construed as requiring the operations to be performed in the specific order shown or sequentially, or to perform all of the shown operations to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0112] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that this disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A first device, comprising: at least one processor; as well as At least one memory including computer program code; The at least one memory and the computer program code are configured to, together with the at least one processor, cause the first device to at least: The second device receives configuration information associated with the serving cell change process of the first device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; During the serving cell change process, a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell are executed, wherein the second random access procedure is initiated at the same time as the first random access procedure or after a first time interval, and wherein the first time interval is shorter than a second time interval configured by the second device to indicate failure in the serving cell change process, wherein the serving cell change process includes at least one of the following: handover of the primary cell of the first device, or change of the secondary primary cell of the first device; as well as After the serving cell change process is completed, access is made to the target cell determined from the first candidate cell and the second candidate cell.

2. The first device according to claim 1, wherein the first device is caused to perform the first random access procedure and the second random access procedure in such a way as: Determine whether the first random access response of the first random access procedure was received by the first device within the first time interval; and If it is determined that the first random access response has not been received within the first time interval, the second random access procedure is executed.

3. The first device according to claim 1, wherein the first device is caused to access the target cell by: Access to the second candidate cell is completed when it is determined that the first random access response of the first random access procedure has not been received by the first device and the second random access response of the second random access procedure has been received by the first device.

4. The first device according to claim 1, wherein the first device is caused to access the target cell by: Based on the determination that both the first random access response of the first random access procedure and the second random access response of the second random access procedure have been received by the first device, and the first candidate cell has been selected as the target cell, the access to the first candidate cell is completed.

5. The first device according to claim 1, wherein the first device is further caused to: Based on the determination that the first device is to be accessed to the first candidate target cell, the second random access procedure is released.

6. The first device of claim 5, wherein the first device is caused to release the second random access procedure by: The second random access procedure is released once it is determined that the first random access response to the first random access procedure has been received by the first device.

7. The first device of claim 5, wherein the first device is caused to release the second random access procedure by: Based on the determination that the second random access response of the second random access procedure has been received by the first device, the resources granted to the first device are determined from the second random access response; and The resource is used to transmit a message to the fourth device for releasing the second random access procedure.

8. The first device of claim 5, wherein the first device is caused to release the second random access procedure by: Determine whether the second random access response of the second random access procedure is received by the first device within a third time interval, the third time interval being configured for the first device to receive the second random access response; and If it is determined that the second message has not been received within the third time interval, the second random access procedure is released.

9. The first device according to claim 1, wherein the first device includes a terminal device, the second device includes a network device, the third device includes a network device, and the fourth device includes a network device.

10. A method comprising: The second device receives configuration information associated with the serving cell change process of the first device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; During the serving cell change process, a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell are executed, wherein the second random access procedure is initiated at the same time as the first random access procedure or after a first time interval, and wherein the first time interval is shorter than a second time interval configured by the second device to indicate failure in the serving cell change process, wherein the serving cell change process includes at least one of the following: handover of the primary cell of the first device, or change of the secondary primary cell of the first device; as well as After the serving cell change process is completed, access is made to the target cell determined from the first candidate cell and the second candidate cell.

11. The method of claim 10, wherein performing the first random access procedure and the second random access procedure comprises: Determine whether the first random access response of the first random access procedure was received by the first device within the first time interval; as well as If it is determined that the first random access response has not been received within the first time interval, the second random access procedure is executed.

12. The method of claim 10, wherein accessing the target cell comprises: Access to the second candidate cell is completed when it is determined that the first random access response of the first random access procedure has not been received by the first device and the second random access response of the second random access procedure has been received by the first device.

13. The method of claim 10, wherein accessing the target cell comprises: Based on the determination that both the first random access response of the first random access procedure and the second random access response of the second random access procedure have been received by the first device, and the first candidate cell has been selected as the target cell, the access to the first candidate cell is completed.

14. The method of claim 10, further comprising: Based on the determination that the first device is to be accessed to the first candidate cell, the second random access procedure is released.

15. The method of claim 14, wherein releasing the second random access procedure comprises: The second random access procedure is released once it is determined that the first random access response to the first random access procedure has been received by the first device.

16. The method of claim 14, wherein releasing the second random access procedure comprises: Based on the determination that the second random access response of the second random access procedure has been received by the first device, the resources granted to the first device are determined from the second random access response; as well as The resource is used to transmit a message to the fourth device for releasing the second random access procedure.

17. The method of claim 14, wherein releasing the second random access procedure comprises: Determine whether the second random access response of the second random access procedure is received by the first device within a third time interval, the third time interval being configured for the first device to receive the second random access response; as well as If it is determined that the second message has not been received within the third time interval, the second random access procedure is released.

18. The method of claim 10, wherein the first device includes a terminal device, the second device includes a network device, the third device includes a network device, and the fourth device includes a network device.

19. An apparatus comprising: A component for receiving configuration information associated with a serving cell change process of a first device from a second device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device that can be used in the serving cell change process; Components for performing a first random access procedure for accessing the first candidate cell and a second random access procedure for accessing the second candidate cell during the serving cell change process, wherein the second random access procedure is initiated at the same time as the first random access procedure or after a first time interval, and wherein the first time interval is shorter than a second time interval configured by the second device to indicate failure in the serving cell change process, wherein the serving cell change process includes at least one of the following: handover of the primary cell of the first device, or change of the secondary primary cell of the first device; as well as A component for accessing the target cell determined from the first candidate cell and the second candidate cell after the serving cell change process is completed.

20. A non-transitory computer-readable medium comprising program instructions for causing a device to perform at least the method according to any one of claims 10 to 18.

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