WO2024168618A1

WO2024168618A1 - Devices and methods for communication

Info

Publication number: WO2024168618A1
Application number: PCT/CN2023/076270
Authority: WO
Inventors: Da Wang; Gang Wang
Original assignee: Nec Corporation
Priority date: 2023-02-15
Filing date: 2023-02-15
Publication date: 2024-08-22

Abstract

Embodiments of the present disclosure provide a solution for self-organising networks (SON). In the solution, a terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) detects a failure of the MCG, initiates, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG; during the MCG recovery procedure, in response to detecting unavailability of the SCG, storing proper formation for a radio link failure (RLF) report.

Description

DEVICES AND METHODS FOR COMMUNICATION

FIELDS

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to devices and methods for self-organising networks (SON) .

BACKGROUND

Wireless communication networks are widely deployed and can support various types of service applications for terminal devices. Many communication schemes have been proposed to enhance the performance of the communication network. For example, a technology of SON, which encompasses solutions for network self-configuration and self-optimisation, has been introduced to support deployment of the system and performance optimization.

In addition, during the operations, both the terminal device and the network device may suffer some failures which may interrupt any pending communication, and both the terminal device and the network device may trigger some operations to recover from the failures. Further, in order to fast recover from the failures and reduce the probability of the failure in future efficiently, both the terminal device and the network device may store related operation information which is helpful and useable. During a procedure of master cell group (MCG) recovery procedure, a procedure of small data transmission (SDT) or a procedure of cell change/addition, the related operation information dose not stored and reported properly, which impacts the performance improvement of the network device.

SUMMARY

In general, embodiments of the present disclosure provide methods, devices and computer storage medium for SON.

In a first aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: detect, at the terminal device associated with an MCG of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG; initiate, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG; during the MCG recovery procedure, in response to detecting unavailability of the SCG, store first formation for a radio link failure (RLF) report, the first information including at least one of the following: at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously, an identity of a primary cell of the SCG, a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected, a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or random access (RA) -related information associated with the SCG.

In a second aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: detect, at the terminal device associated with an MCG of an MN and an SCG of an SN, a failure of the MCG; in response to detecting the failure of the MCG, initiate a MCG recovery procedure, and transmit second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or RA-related information associated with the MCG.

In a third aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a terminal device associated with an MCG of an MN and an SCG of an SN, second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or RA-related information associated with the MCG.

In a fourth aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: generate, a RA report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT; and transmit the RA report to a network device.

In a fifth aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a RA report of a RA procedure, the RA report being associated with an SDT and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

In a sixth aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: receive, a successful PSCell change/addition report (SPR) configuration from a network device; in response to a successful completion of PSCell change or addition procedure, store SPR information according to the SPR configuration; and release the SPR configuration or discard the SPR information if detecting at least one of the following: SCG release, a completion of handover procedure, an initiation of radio resource control (RRC) connection re-establishment procedure, an initiation of RRC connection resume procedure, or a successful completion of PSCell change or addition procedure.

In a seventh aspect, there is provided a communication method performed by a terminal device. The method comprises: detecting, at the terminal device associated with an MCG of an MN and an SCG of an SN, a failure of the MCG; initiating, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG; during the MCG recovery procedure, in response to detecting unavailability of the SCG, storing first formation for an RLF report, the first information including at least one of the following: at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously, an identity of a primary cell of the SCG, a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected, a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or RA-related information associated with the SCG.

In an eighth aspect, there is provided a communication method performed by a terminal device. The method comprises: detecting, at the terminal device associated with an MCG of an MN and an SCG of an SN, a failure of the MCG; in response to detecting the failure of the MCG, initiating a MCG recovery procedure, and transmitting second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or RA-related information associated with the MCG.

In a ninth aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a terminal device associated with an MCG of an MN and an SCG of an SN, second information including at least one of the following: at least one identity of at least one PCell that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or RA-related information associated with the MCG.

In a tenth aspect, there is provided a communication method performed by a terminal device. The method comprises: generating, a RA report of a RA procedure, the RA report being associated with an SDT and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT; and transmitting the RA report to a network device.

In an eleventh aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a terminal device, a RA report of a RA procedure, the RA report being associated with an SDT and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

In a twelfth aspect, there is provided a communication method performed by a terminal device. The method comprises: receiving, a successful PSCell change/addition report (SPR) configuration from a network device; in response to a successful completion of PSCell change or addition procedure, soring SPR information according to the SPR configuration; and releasing the SPR configuration or discarding the SPR information if detecting at least one of the following: SCG release, a completion of handover procedure, an initiation of RRC connection re-establishment procedure, an initiation of RRC connection resume procedure, or a successful completion of PSCell change or addition procedure.

In a thirteenth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the first, second, third, fourth, fifth, or sixth aspect.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some example embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

FIG. 1A illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

FIG. 1B illustrates another example communication environment in which example embodiments of the present disclosure can be implemented;

FIG. 2 illustrates a signaling flow for communication in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates another signaling flow for communication in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates a further signaling flow for communication in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 7 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure;

FIG. 8 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 9 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure;

FIG. 10 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 11 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, devices on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g., FR1 (e.g., 450 MHz to 6000 MHz) , FR2 (e.g., 24.25GHz to 52.6GHz) , frequency band larger than 100 GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator. In some embodiments, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In some embodiments, the first network device may be a first RAT device and the second network device may be a second RAT device. In some embodiments, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In some embodiments, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In some embodiments, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘one embodiment’ and ‘an embodiment’ are to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As used herein, the term “resource, ” “transmission resource, ” “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

As discussed above, a technology of SON, which encompasses solutions for network self-configuration and self-optimisation, has been introduced to support deployment of the system and performance optimization.

In addition, during the operations, both the terminal device and the network device may suffer some failures which may interrupt any pending communication., and both the terminal device and the network device may trigger some operations to recover from the failures. Further, in order to fast recover from the failures and reduce the probability of the failure in future efficiently, both the terminal device and the network device may store related operation information which is helpful and useable.

As discussed previously, in conventional solutions, the related operation information is not stored and reported properly during certain procedures, such as, MCG recovery procedure, SDT or a cell change/addition, which impacts the performance improvement of the network device.

Embodiments of the present disclosure provide solutions for SON. According to some embodiments of the present discourse, the behavior of the terminal device and the network device during procedures, such as, MCG recovery procedure, SDT or a cell change/addition, will be well stipulated. The performance of the network would be enhanced accordingly.

Principles and implementations of the present disclosure will be described in detail below with reference to the figures.

The terms “SCG suspension” and “SCG deactivation” are used interchangeably herein.

The terms “MCG recovery” and “fast MCG recovery” are used interchangeably herein.

EXAMPLE OF COMMUNICATION NETWORK

FIG. 1A shows an example communication environment 100 in which example embodiments of the present disclosure can be implemented. The network communication 100 includes a terminal device 110, a network device 120-1 and optional network devices 120-2 and 120-3. In the following text, the network devices 120-1, 120-2 and 120-3 are collectively referred to as the network devices 120 or individually referred to as the network device 120. Additionally, the network devices 120 may provide one or more coverage areas. Further, each network device 120-1 may provide one or more respective coverage areas (not shown, also referred to as cell in the following text) , and when the terminal device is within the cell (s) , the terminal device 110 may access to network device 120 (s) .

In the communication environment 100, a link from the terminal device 110 to the network device 120 is referred to as an uplink, while a link from the network device 120 to the terminal device 110 is referred to as a downlink. In downlink, the network device 120 is a transmitting (TX) device (or a transmitter) and the terminal device 110 is a receiving (RX) device (or a receiver) . In uplink, the terminal device 110 is a TX device (or a transmitter) and the network device 120 is a RX device (or a receiver) .

In the specific example of FIG. 1A, the terminal device 110 may be in different states (such as, connected state, inactive state and idle state) . When the terminal device 110 is in the connected state, the terminal device 110 can perform transmission of data from all radio bearers. Further, in some embodiments, when the terminal device 110 is in idle state, the terminal device 110 usually is not allowed to perform any data transmission. In addition, when the terminal device 110 is in the inactive state, an SDT is supported while a transmission of data configured with SDT is allowed during an SDT procedure.

In addition, in the example of FIG. 1A, the terminal device 110 may move over time. As illustrated in FIG. 1A, the terminal device 110 locates at different positions at different time points (T1 and T2) . Further, the channel condition also may be changed dynamically. As a result, the connection relationship between the terminal device 110 and the second device 120 is dynamically changed, and related cell (s) may be added/modified/deleted.

In some embodiments, the terminal device 110 may be operated in a dual connectivity mode. In the dual connectivity mode, the terminal device may be configured to utilize radio resources provided by two network devices 120. In the specific embodiment of FIG. 1A, the terminal device 120 may be served by both of the network device 120-1 and 120-2.

For better understanding of the dual connectivity mode, reference is now made to FIG. 1B, which illustrates a specific example communication environment 140 in which example embodiments of the present disclosure can be implemented. For the purpose of discussion, reference is made to FIG. 1A to describe the communication environment 150.

In the example of FIG. 1B, the network devices 120-1 and 120-2 are deployed to serve the terminal device 110. The network device 120-1 serves the terminal device 110 as the MN, while the network device 120-2 serves the terminal device 110 as the SN.

As shown in FIG. 1B, a group of cells of the network device 120-1 includes a primary cell 150-1 and a secondary cell 150-2. Since the network device 120-1serves as the MN, the group of cells of the network device 120-1 is referred to as MCG 150 and the primary cell 150-1 is also referred to as PCell 150-1.

A group of cells of the network device 120-2 includes a primary cell 160-1 and a secondary cell 160-2. Since the network device 120-2 serves as the SN, the group of cells of the network device 120-2 is referred to as SCG 160. The PCell 150-1 of MCG 150 or the primary cell 160-1 of the SCG 160 may be referred to as SpCell. Further the SpCell of the SCG 160 (i.e., the primary cell 160-1 of the SCG 160) may be referred to as PSCell.

Similar with the discussions made to FIG. 1A, the relationship between the terminal device 110 and the MN (i.e., the network device 120-1) , SN (i.e., the network device 120-2) , MCG, SCG, primary cell and so on may be dynamically changed according to specific communication scenarios.

In the present disclosure, as for mobility robustness optimisation (MRO) , a feature of fast MCG recovery is supported. Further, if detects an expiry of T316 or a failure/deactivation of the SCG during the fast MCG recovery, the terminal device 110 determines that the fast MCG recovery is failed. Further, during the fast MCG recovery procedure, the terminal device may store information for the RLF report.

It is to be understood that the number of devices and their connections shown in FIG. 1A and FIG. 1B are only for the purpose of illustration without suggesting any limitation. The communication environments 100 and 140 may include any suitable number of devices configured to implementing example embodiments of the present disclosure. Although not shown, it would be appreciated that one or more additional devices may be located in the communication environment 100. It is noted that although illustrated as a network device, the network device 120 may be another device than a network device. Although illustrated as a terminal device, the terminal device 110 may be other device than a terminal device.

In the following, for the purpose of illustration, some example embodiments are described with the terminal device 110 operating as a UE and the network device 120 operating as a base station. However, in some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other device.

The communications in the communication environment 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New Radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

EXAMPLE OF PROCESSES

It should be understood that although feature (s) /operation (s) are discussed in specific example embodiments separately, unless clearly indicated to the contrary, these feature (s) /operation (s) described in different example embodiments may be used in any suitable combination.

Example processes about MCG recovery procedure

In conventional solutions, the upon detection of MCG failure, the UE may starttimer T316 and reports the failure of MCG with MCGFailureInformation message to the MN via the SCG. In some scenarios, although the failure of the MCG occurs, the downlink transmission from the MN also may be performed, which means that the UE also may receive a first indication (such as, scg-State) to deactivate the SCG when timer T316 is running. Further, the UE also may detect a failure of the SCG when timer T316 is running. That is, during an MCG recovery procedure, the SCG may be deactivated or failed. Conventional solutions fail to stipulate proper behaviors of the UE and/or the network device under the above scenarios.

According to the example embodiments as discussed below, if a failure/deactivation of the SCG is detected during the MCG recovery, the historical operation of the SCG (especially the information that related to the failure of the MCG recovery procedure) may be properly stored (such as, stored in VarRLF-Report) .

Reference is made to FIG. 2, which illustrates a signaling flow 200 for communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 200 will be discussed with reference to FIG. 1A and 1B, for example, by using the terminal device 110 and the network devices 120-1 and 120-2.

In the specific embodiment of FIG. 2, the terminal device 110 is operated in a dual connectivity mode and configured to utilize the radio resources of both the network devices 120-1 and 120-2.

Further, the network device 120-1 serves the terminal device 110 as the MN, while the network device 120-2 serves the terminal device 110 as the SN, i.e., the terminal device 110 is associated with the MCG 150 and the SCG 160. In the following text, the network device 120-1 also may be referred to as the MN 120-1, and the network device 120-1 also may be referred to as the SN 120-2.

In operation, the terminal device 110 detects 210 a failure of the MCG 150. It should be understood that a plurality of reasons may cause a failure of the MCG 150, including but not limited to, detecting a RLF failure with the MCG 150, receiving a message for switching from the MCG 150 and so on. In summary, the failure of the MCG causes that the uplink transmission to the network device 120-1 cannot be performed.

Upon the failure of the MCG 150, the terminal device 110 initiates 230 an MCG recovery procedure via the SCG 160. Additionally, in some embodiment, the terminal device 110 transmits 232 a message (such as, MCGFailureInformation message) indicating the failure of the MCG 150 to the network device 120-2, and the network device 120-2 may forward 234 this message to the network device 120-1.

Additionally, in some embodiments, the terminal device 110 may start 220 a timer (i.e., timer T316) to control the MCG recovery procedure.

Then, during the MCG recovery procedure, the terminal device 110 may detect 240 unavailability of the SCG 160. In some embodiments, the unavailability of the SCG 160 may be caused by receiving 244 a first indication (such as, scg-State) to deactivate the SCG 160 from the network device 120-1 (as discussed above, even the MCG 150 is failure, the downlink transmission from the network device 120-1 also may be proceed) . Alternatively, the network device 120-1 also may transmit the first indication via the network device 120-2. In summary, the terminal device 110 may receive the first indication to deactivate the SCG 160 during the MCG recovery procedure, and the receipt of the first indication may cause the unavailability of the SCG 160.

In some other embodiment, the unavailability of the SCG 160 may be caused by detecting 242 a failure of the SCG. In one specific embodiment, the terminal device 110 performs radio link measurement on the SCG 160, and may detect the failure of the SCG 160 based on the measurement results.

In the present disclosure, if the terminal device 110 detects the unavailability of the SCG 160, the terminal device 110 stores 260 first information for an RLF report (such as, stored in VarRLF-Report) . According to some embodiments of the present disclosure, the first information is about historical information of the SCG 160.

In some embodiments, the first information may include at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously, i.e., previous PSCell ID (s) . Such information may help the network to identity whether the failure of SCG 160 during the MCG recovery is caused due to too early PSCell change.

Alternatively, or in addition, in some embodiments, the first information may include an identity of a primary cell of the SCG, i.e., the failed PSCell ID. Such information may help the network to identity whether the failure of SCG 160 during the MCG recovery is caused due to triggering PSCell change to wrong PSCell.

Alternatively, or in addition, in some embodiments, the first information may include a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG 160 (i.e., PSCell change or addition) and a time point at which the unavailability of the SCG 160 is detected. Such information may help the network to identity the timeline information of the unsuccessful MCG recovery.

Alternatively, or in addition, in some embodiments, the first information may include a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected. Such information may help the network to identity the timeline information of the unsuccessful MCG recovery.

Alternatively, or in addition, in some embodiments, the first information may include RA-related information associated with the SCG 160. In some embodiments, the RA-related information indicates detailed information about each of the RA procedure attempts in the chronological order of the RA attempts. In some embodiments, the RA-related information is parameter perRAInfoList. Such information may help the network to identity the RA problem (s) of the SCG 160 during the MCG recovery procedure.

It is to be understood that the above illustrated examples of the first information are given for illustrative purpose only. It should be understood that any suitable historical information of the SCG 160 may be included in the first information. The present disclosure is not limited in this regard.

Further, as discussed above, the unavailability of the SCG 160 may be caused by either a failure of the SCG 160 or a deactivation of the SCG 160.

Generally speaking, upon the failure of the SCG 160, the terminal device 110 may initiate a connection re-establishment procedure with the network device 120-2.

In conventional solution, during an MCG recovery procedure, if the SCG is deactivated, the UE does not initiate a connection re-establishment procedure. However, such operation is improper, because a deactivation of the SCG during the MCG recovery procedure will result the communication between the UE and the network interrupted, and the UE experience is reduced accordingly.

In some embodiments of the present disclosure, similar with the processes for handling the failure of the SCG 160, the terminal device 110 also may initiate 250 a connection re-establishment procedure with the network device 120-2 upon the receipt of first indication to deactivate the SCG.

According to the above procedure, the historical information of the SCG 160 may be stored properly. In the following text, examples about how to handle the historical information of the MCG 150 will be described.

Generally speaking, the terminal device 110 may execute a reconfiguration with sync sometimes or a RRC release procedure upon a successful MCG recovery.

The behaviour of terminal device 110 about how to execute a reconfiguration with sync sometimes is listed as below. Specifically, the terminal device 110 may perform the following actions to execute a reconfiguration with sync.

The behaviour of terminal device 110 about how to execute a RRC release procedure is listed as below. Specifically, the terminal device 110 may perform the following actions to release an RRC connection.

It can be seen that, upon the failure of MCG 150, the terminal device 110 may store the MCG failure information in RLF report. Further, if a message of reconfigurationWithSync for the MCG 150 is received or a message of RRCRelease is received (which may imply a successful MCG recovery procedure) , the terminal device 110 would stop the T316 timer and discard RLF-report. That is, upon a successful MCG recovery procedure, the terminal device 110 would clear the information stored for RLF report. However, in practice, the the terminal device 110 may store historical information of the MCG 150, which is useful for improving the network maintaining in future. In view of this, the stored historical information of the MCG 150 is needed to be provided to the network.

Still refer to FIG. 2. In operation, the terminal device 110 detects 210 the failure of the MCG 150 as discussed above. Upon the failure of the MCG 150, the terminal device 110 initiates 230 an MCG recovery procedure.

In the present disclosure, the terminal device 110 further transmits second information about historical information of the MCG 150.

In some embodiments, the second information may include at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously.

Alternatively, or in addition, in some embodiments, the second information may include an identity of a PCell of the MCG.

Alternatively, or in addition, in some embodiments, the second information may include a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected. Such information may help the network to identity whether the failure of the MCG 150 during the MCG recovery procedure is caused due to too early handover.

Alternatively, or in addition, in some embodiments, the second information may include RA-related information associated with the MCG 150. In some embodiments, the RA-related information indicates detailed information about each of the RA procedure attempts in the chronological order of the RA attempts. In some embodiments, the RA-related information is parameter perRAInfoList. Such information may help the network to identity the RA problem (s) of the MCG 150 during the MCG recovery.

Additionally, in some embodiments, the terminal device 110 transmits the RA-related information associated with the MCG only if the failure of the MCG is caused by a failure of an RA, i.e. the MCG failure type is random access failure problem.

According to some embodiments of the present discourse, the second information may be transmitted to any suitable device and via proper signalling. In one specific embodiment, the second information is transmitted via MCG failure information which is used by the terminal device 110 to initiate an MCG recovery procedure.

Alternatively, in another specific embodiment, the second information is transmitted via a failure report transmitted in response to receiving a request for the second information. In this event, the terminal device 110 may need to store the second information first and then reports the second information to the network if the network requests for it.

Example processes about SDT procedure

In the present disclosure, RA-based SDT is supported. In the following examples, the RA-related information and the SDT information comprised in the RA report of a SDT may be further enriched.

Reference is made to FIG. 3, which illustrates a signaling flow 300 for communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 300 will be discussed with reference to FIG. 1A and 1B, for example, by using the terminal device 110 and the network device 120-1.

In operation, the terminal device 110 generates an RA report of an RA procedure, where the RA report is associated with an SDT. In the present discourse, more details about the SDT may be reported in the RA report.

In some embodiments, the RA report comprises a second indication indicating the RA procedure is associated with the SDT. In other words, the RA purpose in RA-report is set to a value indicating SDT.

Alternatively, or in addition, in some embodiments, the RA report comprises a third indication indicating the RA procedure is successful.

Alternatively, or in addition, in some embodiments, the RA report comprises a fourth indication indicating the RA procedure is failed.

Alternatively, or in addition, in some embodiments, the RA report comprises a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT.

Alternatively, or in addition, in some embodiments, the RA report comprises a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

In order to ensure the rationality of resources usage, in some embodiments, the RA resources (also referred to as RACH resources) are partitioned for different features or feature combinations. Specifically, the network may associate a set of RA resources with feature (s) applicable to an RA procedure. Examples of feature may be Network Slicing RedCap, SDT, and NR coverage enhancement.

Further, a set of RA resources associated with a feature is only valid for RA procedures applicable to at least that feature; and a set of RA resources associated with several features is only valid for random access procedures having at least all of these features. The terminal device 110 may select the set (s) of applicable RA resources, after uplink carrier (i.e., normal uplink or supplementary uplink) and bandwidth part (BWP) selection and before selecting the RA type.

In some embodiments, if the RA procedure is triggered during the initial transmission of the SDT, the RA report further indicates RA partition information associated with the RA procedure.

In some embodiments, the RA partition information indicates at least one of the following: a feature or a feature combination that triggers the RA procedure, or a feature or a feature combination corresponding to RA resources used by the RA procedure.

In some embodiments, the RA report is generated upon a completion of the SDT. Alternatively, in some embodiments, the RA report is generated upon a completion of the RA procedure. In one specific embodiments, upon a successful or failed completed RA procedure while SDT procedure is on going, the terminal device 110 set/include the above information in ra-InformationCommon of RA report.

Example processes about SPR

Currently, an SPR configuration may be received by the terminal device 110, where triggering condition (s) for storing the SPR configuration is indicated in the SPR configuration. with the SPR configuration, the terminal device 110 may store SRS information if the triggering condition in the SPR configuration is fulfilled.

However, keeping the SPR configuration and the stored SPR information may consume resources. Thus, it is expected that the SPR configuration may be released and the SRS information may be discarded in time. According to the following discussed example embodiments, the processes for releasing the SPR configuration and discarding the SPR information will be discussed in detail.

Reference is made to FIG. 4, which illustrates a signaling flow 400 for communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 200 will be discussed with reference to FIG. 1A and 1B, for example, by using the terminal device 110 and the network devices 120.

In operation, the terminal device 110 receives 420 an SPR configuration from a network device 120. In the specific example of FIG. 4, the network device 120 is the following an MN, a source SN or a target SN.

Next, in response to a successful completion of PSCell change or addition procedure, the terminal device 110 stores 420 SPR information according to the SPR configuration. In other words, upon successful completion of random access procedure triggered for the reconfigurationWithSync of the SCG, the terminal device 110 stores 420 SPR information according to the SPR configuration.

According to some embodiments of the present, the operation of releasing the SPR configuration may be triggered by certain events. One example of the event may SCG release. Another example of the event may a completion of handover procedure. Further examples of the event may be an initiation of RRC connection re-establishment procedure, an initiation of RRC connection resume procedure and a successful completion of PSCell change or addition procedure.

In some embodiments, if the operation of releasing the SPR configuration is triggered by detecting the SCG release or the successful completion of PSCell change or addition procedure, the terminal device 110, only the SPR configuration received from the source or target SN is released.

According to some embodiments of the present, the operation of discarding the SPR information also may be triggered by certain events. One example of the event may SCG release. Another example of the event may a completion of handover procedure. Further examples of the event may be an initiation of RRC connection re-establishment procedure, and an initiation of RRC connection resume procedure.

EXAMPLE OF METHODS

FIG. 5 illustrates a flowchart of a communication method500 implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method500 will be described from the perspective of the terminal device 110 in FIG. 1A and FIG. 1B.

At block 510, the terminal device 110 detects, at the terminal device 110 associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG.

At block 520, the terminal device 110 initiates, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG.

At block 530, during the MCG recovery procedure, in response to detecting unavailability of the SCG, the terminal device 110 stores first formation for a radio link failure (RLF) report, the first information including at least one of the following: At block540, at least one identity of at least one primary cell of at least one respective SCG that served the terminal device 110 previously, an identity of a primary cell of the SCG, a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected, a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or random access (RA) -related information associated with the SCG.

In some example embodiments, the terminal device 110 detects the unavailability of the SCG comprises at least of the following: receiving, from the master node, a first indication to deactivate the SCG, or detecting a failure of the SCG.

In some example embodiments, in response to receiving the first indication, the terminal device 110 initiates a connection re-establishment procedure with the secondary node.

FIG. 6 illustrates a flowchart of a communication method 600 implemented at a terminal device 110 in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the terminal device 110 in FIG. 1A and FIG. 1B.

At block 610, the terminal device 110 detects, at the terminal device 110 associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG.

At block 620, in response to detecting the failure of the MCG, the terminal device 110 initiates an MCG recovery procedure, and transmitting second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device 110 previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG.

In some example embodiments, transmitting the RA-related information associated with the MCG comprises: transmitting the RA-related information associated with the MCG if the failure of the MCG is caused by a failure of an RA.

In some example embodiments, transmitting the second information comprises: transmitting the second information via one of the following: MCG failure information used by the terminal device 110 to initiate an MCG recovery procedure, or a failure report transmitted in response to receiving a request for the second information.

FIG. 7 illustrates a flowchart of a communication method 700 implemented at a network device 120 in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the network device 120 in FIG. 1A and FIG. 1B.

At block 710, the network device 120 receives, from a terminal device 110 associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device 110 previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG.

In some example embodiments, the RA-related information indicates failure information of an RA.

In some example embodiments, the network device 120 is the MN, and receiving the second information comprises: receiving, from the terminal device 110, MCG failure information comprising the second information, the MCG failure information being used by the terminal device 110 to initiate a MCG recovery procedure.

In some example embodiments, the processor is further configured to cause the network device 120 to: transmitting, a request for the second information to the terminal device 110.

FIG. 8 illustrates a flowchart of a communication method 800 implemented at a terminal device 110 in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the terminal device 110 in FIG. 1A and FIG. 1B.

At block 810, the terminal device 110 generates, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

At block 820, the terminal device 110 transmits the RA report to a network device 120.

In some example embodiments, RA resources are partitioned for different features or feature combinations, and if the RA procedure is triggered during the initial transmission of the SDT, the RA report further indicates RA partition information associated with the RA procedure.

In some example embodiments, the RA partition information indicates at least one of the following: a feature or a feature combination that triggers the RA procedure, a feature or a feature combination corresponding to RA resources used by the RA procedure.

In some example embodiments, transmitting the RA report comprises: generating the RA report in response to one of the following: a completion of the SDT, or a completion of the RA procedure.

FIG. 9 illustrates a flowchart of a communication method 900 implemented at a network device 120 in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the network device 120 in FIG. 1A and FIG. 1B.

At block 910, the network device 120 receives, from a terminal device 110, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

FIG. 10 illustrates a flowchart of a communication method 1000 implemented at a terminal device 110 in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of the terminal device 110 in FIG. 1A and 1B.

At block 1010, the terminal device 110 receives, a successful PSCell change/addition report (SPR) configuration from a network device 120.

At block 1020, in response to a successful completion of PSCell change or addition procedure, the terminal device 110 stores SPR information according to the SPR configuration.

At block 1030, the terminal device 110 releases the SPR configuration or discards the SPR information if detecting at least one of the following: secondary cell group (SCG) release, a completion of handover procedure, an initiation of radio resource control (RRC) connection re-establishment procedure, an initiation of RRC connection resume procedure, or a successful completion of PSCell change or addition procedure.

In some example embodiments, if the SCG release or the successful completion of PSCell change or addition procedure is detected, releasing the SPR configuration comprises: releasing the SPR configuration received from a source or target secondary node (SN) .

In some example embodiments, the network device 120 is one of the following a master node (MN) , a source secondary node (SN) or a target SN.

EXAMPLE OF DEVICESAND APPARATUSES

FIG. 11 is a simplified block diagram of a device 1100 that is suitable for implementing embodiments of the present disclosure. The device 1100 can be considered as a further example implementation of any of the devices as shown in FIG. 1A and FIG. 1B. Accordingly, the device 1100 can be implemented at or as at least a part of the terminal device 110 or the network device 120.

As shown, the device 1100 includes a processor 1110, a memory 1120 coupled to the processor 1110, a suitable transmitter (TX) /receiver (RX) 1140 coupled to the processor 1110, and a communication interface coupled to the TX/RX 1140. The memory 1110 stores at least a part of a program 1130. The TX/RX 1140 is for bidirectional communications. The TX/RX 1140 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 1130 is assumed to include program instructions that, when executed by the associated processor 1110, enable the device 1100 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 1 to 10. The embodiments herein may be implemented by computer software executable by the processor 1110 of the device 1100, or by hardware, or by a combination of software and hardware. The processor 1110 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1110 and memory 1120 may form processing means 1150 adapted to implement various embodiments of the present disclosure.

The memory 1120 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1120 is shown in the device 1100, there may be several physically distinct memory modules in the device 1100. The processor 1110 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1100 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG; initiate, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG; during the MCG recovery procedure, in response to detecting unavailability of the SCG, store first formation for a radio link failure (RLF) report, the first information including at least one of the following: at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously, an identity of a primary cell of the SCG, a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected, a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or random access (RA) -related information associated with the SCG. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG; in response to detecting the failure of the MCG, initiate a MCG recovery procedure, and transmit second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: generate, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT; and transmit the RA report to a network device. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: receive, a successful PSCell change/addition report (SPR) configuration from a network device; in response to a successful completion of PSCell change or addition procedure, store SPR information according to the SPR configuration; and releasing the SPR configuration or discarding the SPR information if detecting at least one of the following: secondary cell group (SCG) release, a completion of handover procedure, an initiation of radio resource control (RRC) connection re-establishment procedure, an initiation of RRC connection resume procedure, or a successful completion of PSCell change or addition procedure. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

In summary, embodiments of the present disclosure provide the following aspects.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG; initiate, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG; during the MCG recovery procedure, in response to detecting unavailability of the SCG, store first formation for a radio link failure (RLF) report, the first information including at least one of the following: at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously, an identity of a primary cell of the SCG, a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected, a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or random access (RA) -related information associated with the SCG.

In some embodiments, detecting the unavailability of the SCG comprises at least of the following: receiving, from the master node, a first indication to deactivate the SCG, or detecting a failure of the SCG.

In some embodiments, the processor is further configured to cause the terminal device to: in response to receiving the first indication, initiate a connection re-establishment procedure with the secondary node.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG; in response to detecting the failure of the MCG, initiating a MCG recovery procedure, and transmit second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG.

In some embodiments, transmitting the RA-related information associated with the MCG comprises: transmitting the RA-related information associated with the MCG if the failure of the MCG is caused by a failure of an RA.

In some embodiments, transmitting the second information comprises: transmitting the second information via one of the following: MCG failure information used by the terminal device to initiate a MCG recovery procedure, or a failure report transmitted in response to receiving a request for the second information.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , second information including at least one of the following: at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously, an identity of a PCell of the MCG, a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or random access (RA) -related information associated with the MCG.

In some embodiments, the RA-related information indicates failure information of an RA.

In some embodiments, the network device is the MN, and receiving the second information comprises: receiving, from the terminal device, MCG failure information comprising the second information, the MCG failure information being used by the terminal device to initiate a MCG recovery procedure.

In some embodiments, the processor is further configured to cause the network device to: transmitting, a request for the second information to the terminal device.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: generate, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT; and transmit the RA report to a network device.

In some embodiments, RA resources are partitioned for different features or feature combinations, and if the RA procedure is triggered during the initial transmission of the SDT, the RA report further indicates RA partition information associated with the RA procedure.

In some embodiments, the RA partition information indicates at least one of the following: a feature or a feature combination that triggers the RA procedure, a feature or a feature combination corresponding to RA resources used by the RA procedure.

In some embodiments, transmitting the RA report comprises: generating the RA report in response to one of the following: a completion of the SDT, or a completion of the RA procedure.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following: a second indication indicating the RA procedure is associated with the SDT, a third indication indicating the RA procedure is successful, a fourth indication indicating the RA procedure is failed, a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or a sixth indicating the RA procedure is triggered during an initial transmission of the SDT.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: receive, a successful PSCell change/addition report (SPR) configuration from a network device; in response to a successful completion of PSCell change or addition procedure, store SPR information according to the SPR configuration; and release the SPR configuration or discard the SPR information if detecting at least one of the following: secondary cell group (SCG) release, a completion of handover procedure, an initiation of radio resource control (RRC) connection re-establishment procedure, an initiation of RRC connection resume procedure, or a successful completion of PSCell change or addition procedure.

In some embodiments, if the SCG release or the successful completion of PSCell change or addition procedure is detected, releasing the SPR configuration comprises: releasing the SPR configuration received from a source or target secondary node (SN) .

In some embodiments, the network device is one of the following a master node (MN) , a source secondary node (SN) or a target SN.

In an aspect, a terminal device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the terminal device discussed above.

In an aspect, a network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the network device discussed above.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGS. 1 to 11. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A terminal device comprising:

a processor configured to cause the terminal device to:

detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG;

initiate, via the SCG, an MCG recovery procedure in response to detecting the failure of the MCG;

during the MCG recovery procedure, in response to detecting unavailability of the SCG, store first formation for a radio link failure (RLF) report, the first information comprising at least one of the following:

at least one identity of at least one primary cell of at least one respective SCG that served the terminal device previously,

an identity of a primary cell of the SCG,

a first time length from a time point at which a last reconfiguration with synchronization is performed on the SCG and a time point at which the unavailability of the SCG is detected,

a second time length from a time point at which the failure of the MCG is detected and a time point at which the unavailability of the SCG is detected, or

random access (RA) -related information associated with the SCG.
The terminal device of claim 1, wherein detecting the unavailability of the SCG comprises at least of the following:

receiving, from the MN, a first indication to deactivate the SCG, or

detecting a failure of the SCG.
The terminal device of claim 2, wherein the processor is further configured to cause the terminal device to:

in response to receiving the first indication, initiate a connection re-establishment procedure with the SN.
A terminal device comprising:

a processor configured to cause the terminal device to:

detect, at the terminal device associated with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN) , a failure of the MCG;

in response to detecting the failure of the MCG, initiate an MCG recovery procedure via the SCG, and transmit second information comprising at least one of the following:

at least one identity of at least one primary cell (PCell) of at least one respective MCG that served the terminal device previously,

an identity of a PCell of the MCG,

a third time length from a time point at which a last handover procedure is executed to a time point at which the failure of the MCG is detected, or

random access (RA) -related information associated with the MCG.
The terminal device of claim 4, wherein transmitting the RA-related information associated with the MCG comprises:

transmitting the RA-related information associated with the MCG if the failure of the MCG is caused by a failure of an RA.
The terminal device of claim 4, wherein transmitting the second information comprises:

transmitting the second information via one of the following:

MCG failure information used by the terminal device to initiate a MCG recovery procedure, or

a failure report transmitted in response to receiving a request for the second information.
A terminal device comprising:

a processor configured to cause the terminal device to:

generate, a random access (RA) report of a RA procedure, the RA report being associated with a small data transmission (SDT) and comprising at least one of the following:

a second indication indicating the RA procedure is associated with the SDT,

a third indication indicating the RA procedure is successful,

a fourth indication indicating the RA procedure is failed,

a fifth indication indicating the RA procedure is triggered during a subsequent transmission of the SDT, or

a sixth indicating the RA procedure is triggered during an initial transmission of the SDT; and

transmit the RA report to a network device.
The terminal device of claim 7, wherein RA resources are partitioned for different features or feature combinations, and

if the RA procedure is triggered during the initial transmission of the SDT, the RA report further indicates RA partition information associated with the RA procedure.
The terminal device of claim 7, wherein the RA partition information indicates at least one of the following:

a feature or a feature combination that triggers the RA procedure, or

a feature or a feature combination corresponding to RA resources used by the RA procedure.
The terminal device of claim 7, wherein the RA report is generated in response to one of the following:

a completion of the SDT, or

a completion of the RA procedure.
A terminal device comprising:

a processor configured to cause the terminal device to:

receive, a successful PSCell change/addition report (SPR) configuration from a network device;

in response to a successful completion of PSCell change or addition procedure, store SPR information according to the SPR configuration; and

release the SPR configuration or discard the SPR information if detecting at least one of the following:

secondary cell group (SCG) release,

a completion of handover procedure,

an initiation of radio resource control (RRC) connection re-establishment procedure,

an initiation of RRC connection resume procedure, or

a successful completion of PSCell change or addition procedure.
The terminal device of claim 11, wherein if the SCG release or the successful completion of PSCell change or addition procedure is detected, releasing the SPR configuration comprises:

releasing the SPR configuration received from a source or target secondary node (SN) .
The terminal device of claim 11, wherein the network device is one of the following a master node (MN) , a source secondary node (SN) or a target SN.