WO2023097430A1

WO2023097430A1 - Method, device and computer storage medium of communication

Info

Publication number: WO2023097430A1
Application number: PCT/CN2021/134321
Authority: WO
Inventors: Gang Wang
Original assignee: Nec Corporation
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2023-06-08

Abstract

Embodiments of the present disclosure relate to methods, devices and computer readable media for communication. A terminal device receives a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of a first access network device or a location of the terminal device. If the condition is satisfied, the terminal device performs the operation comprising: a neighbor cell measurement before a RLF is detected, a re-establishment of a connection between the terminal device and a target cell of a second access network device, or a suspending of the terminal device. In this way, a time taken for RRC reestablishment to another cell may be reduced, power consumption due to unnecessary recovery procedure may be reduced and related suspend signaling may be reduced.

Description

METHOD, DEVICE AND COMPUTER STORAGE MEDIUM OF COMMUNICATION

FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, devices and computer storage media of communication.

BACKGROUND

Currently, a non-terrestrial network (NTN) is proposed to provide wide area coverage. A NTN refers to networks or segments of networks using an airborne or space-borne vehicle to embark a transmission equipment relay node or base station or using radio frequency (RF) resources on board a satellite or unmanned aerial system (UAS) platform.

When a narrow band-Internet of things (NB-IoT) user equipment (UE) goes out of service coverage of the source cell, it experiences a radio link failure (RLF) . This triggers the UE to perform a re-establishment for a radio resource control (RRC) connection. Propagation delay in NTN is orders of magnitude higher than terrestrial systems, introducing additional latency to mobility signaling such as measurement reporting, reception of a handover command, and handover request/acknowledgement (ACK) if a target cell originates from a different satellite. Thus, enhancements on RLF and RRC re-establishment for NTN are needed.

SUMMARY

In general, embodiments of the present disclosure provide methods, devices and computer storage media of communication.

In a first aspect, there is provided a method of communication. The method comprises: receiving, at a terminal device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of a first access network device or a location of the terminal device; and in accordance with a determination that the condition is satisfied, performing the operation, the operation comprising: a neighbor cell measurement before a radio link failure is detected, a re-establishment of a connection between the terminal device and a target cell of a second access network device, or a suspending of the terminal device.

In a second aspect, there is provided a method of communication. The method comprises: transmitting, at a first access network device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the first access network device or a location of a terminal device, the operation comprising: a neighbor cell measurement before a radio link failure is detected, a re-establishment of a connection of the terminal device to a target cell of a second access network device, or a suspending of a context of the terminal device.

In a third aspect, there is provided a device of communication. The device comprises a processor configured to perform the method according to the first aspect of the present disclosure.

In a fourth aspect, there is provided a device of communication. The device comprises a processor configured to perform the method according to the second aspect of the present disclosure.

In a fifth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to perform the method according to the first aspect of the present disclosure.

In a sixth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to perform the method according to the second aspect of the present disclosure.

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:

Through the more detailed description of some 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. 1 illustrates an example communication environment in which some embodiments of the present disclosure can be implemented;

Fig. 2 illustrates a schematic diagram illustrating a process for communication according to embodiments of the present disclosure;

Fig. 3 illustrates a schematic diagram illustrating an example timeline for a re-establishment of RRC connection according to embodiments of the present disclosure;

Fig. 4 illustrates a schematic diagram illustrating another process for communication according to embodiments of the present disclosure;

Fig. 5 illustrates a schematic diagram illustrating still another process for communication according to embodiments of the present disclosure;

Fig. 6 illustrates a schematic diagram illustrating yet another process for communication according to embodiments of the present disclosure;

Fig. 7 illustrates an example method of communication implemented at a terminal device in accordance with some embodiments of the present disclosure;

Fig. 8 illustrates an example method of communication implemented at an access network device in accordance with some embodiments of the present disclosure; and

Fig. 9 is a simplified block diagram of a device that is suitable for implementing 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.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall 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 only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. 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. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

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 “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, 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) , 5.5G, 5G-Advanced networks, or the sixth generation (6G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

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, device 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 incorporated 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 “core network (CN) device” refers to any device or entity that provides access and mobility management function, session management function (SMF) , user plane function (UPF) , etc. By way of example rather than limitation, the CN device may be a mobility management entity (MME) , an AMF, a SMF, a UPF, etc. In other embodiments, the CN device may be any other suitable device or entity.

As used herein, the term “access 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 satellite, a unmanned aerial systems (UAS) platform, 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 (410 MHz –7125 MHz) , FR2 (24.25GHz to 71GHz) , frequency band larger than 100GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connections 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.

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.

As discussed above, the NTN is capable of providing wide network coverage. Currently, there may be different types of satellite (or UAS platform) in the NTN. Blow Table 1 illustrated the example types of satellite.

Table 1 Example Types of satellite/UAS platform

Further, the NTN typically features the following elements:

● One or several sat-gateways that connect the NTN to a public data network;

– A GEO satellite is fed by one or several sat-gateways which are deployed across the satellite targeted coverage (e.g. regional or even continental coverage) . We assume that UE in a cell are served by only one sat-gateway;

– A Non-GEO satellite served successively by one or several sat-gateways at a time. The system ensures service and feeder link continuity between the successive serving sat-gateways with sufficient time duration to proceed with mobility anchoring and hand-over.

● A feeder link or radio link between a sat-gateway and the satellite (or UAS platform) .

● A service link or radio link between the user equipment and the satellite (or UAS platform) .

● A satellite (or UAS platform) which may implement either a transparent or a regenerative (with on board processing) payload. The satellite (or UAS platform) generate beams typically generate several beams over a given service area bounded by its field of view. The footprints of the beams are typically of elliptic shape. The field of view of a satellites (or UAS platforms) depends on the on board antenna diagram and min elevation angle.

– A transparent payload: radio frequency filtering, frequency conversion and amplification. Hence, the waveform signal repeated by the payload is un-changed;

– A regenerative payload: radio frequency filtering, frequency conversion and amplification as well as demodulation/decoding, switch and/or routing, coding/modulation. This is effectively equivalent to having all or part of base station functions (e.g., gNB) on board the satellite (or UAS platform) .

● Inter-satellite links (ISL) optionally in case of a constellation of satellites. This will require regenerative payloads on board the satellites. ISL may operate in RF frequency or optical bands.

● UEs are served by the satellite (or UAS platform) within the targeted service area.

Currently, The NTN has been developed to support scenarios of IoT and enhanced machine type communication (eMTC) . Examples of IoT NTN are listed as below.

● Scenario A: GEO based non-terrestrial access network;

● Scenario B: LEO based non-terrestrial access network generating steerable beams, (altitude 1200 km and 600km) , the steerable beams generating one or more earth fixed cells;

● Scenario C: LEO based non-terrestrial access network generating fixed beams whose footprints move with the satellite (altitude 1200 km and 600 km) , the fixed beams generating one or more earth moving cells; and

● Scenario D: MEO based non-terrestrial access network generating fixed beams whose footprints move with the satellite (altitude 10000 km) , the fixed beams generating one or more earth moving cells.

Currently, there are no connected mode mobility procedures defined for NB-IoT. When an NB-IoT UE goes out of service coverage of the source cell, it experiences a RLF. This triggers the UE to perform a re-establishment for a RRC connection. RLF and RRC connection re-establishment procedures are used as a baseline in NB-IoT NTN. Enhancements to reduce the time taken for RRC re-establishment may be considered in NB-IoT NTN. Further minor enhancements can be considered, e.g. by using satellite assistance (ephemeris) information.

Further, in terrestrial systems, a UE may determine it is near a cell edge due to a clear difference in reference signal receive power (RSRP) as compared to cell center. Such an effect may not be as pronounced in non-terrestrial deployments, resulting in a small difference in signal strength between two beams in a region of overlap. As a handover mechanism may be based on measurement events, the UE may thus have difficulty distinguishing the better cell.

The present inventor found that the reduced signal strength variation may have impact on neighbor cell measurement triggering. To avoid an overall reduction in handover robustness due to the UE ping-ponging between cells, this challenge may be addressed with high priority for both GEO and LEO scenarios. Location information and/or satellite ephemeris may be useful in addition to measurement results.

Further, the present inventor found that a NB-IoT UE may trigger a cell search to recovery RRC connection after RLF detection, which may lead to large power consumption when served by sparse cells.

In view of the above, embodiments of the present disclosure provide an improved solution for communication so as to solve the above and other potential problems. In this solution, a terminal device receives, from an access network device (for convenience, also referred to as a first access network device herein) , a configuration indicating a condition for performing an operation. The condition is based on at least one of a quality of a serving cell of the access network device or a location of the terminal device. If the condition is satisfied, the terminal device performs the operation. The operation comprises a neighbor cell measurement before a RLF is detected, a re-establishment of a connection between the terminal device and a target cell of a further access network device (for convenience, also referred to as a second access network device herein) , or a suspending of the terminal device.

In this way, a neighbor cell measurement may be triggered before RLF, and thus a time taken for a RRC reestablishment to another cell may be reduced. Further, a conditional re-establishment may be achieved and a time taken for a RRC reestablishment to another cell may be reduced. Furthermore, a conditional suspend may be achieved, and thus power consumption due to unnecessary recovery procedure may be reduced and related suspend signaling may be also reduced.

Principle and example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

In the following, a satellite will be used as an example of an access network device for describing some specific example embodiments of the present disclosure. It is noted that example embodiments described with regard to the satellite are equally applicable to any other suitable types of an access network device.

EXAMPLE OF COMMUNICATION NETWORK

Fig. 1 shows an example communication environment 100 in which example embodiments of the present disclosure can be implemented. The network environment 100 includes a terminal device 110 and an access network device 121 serving the terminal device 110 and a second access network device 122. Additionally, on or more ISL may be established between the access network device 121 and the access network device 122.

Additionally, any of the

access network devices

121 and 122 may provide one or more serving cells to the terminal device 110. In the example of Fig. 1, the access network device 121 provides a serving cell 123 and the access network device 122 provides a serving cell 124. For convenience, the following description will be given by assuming that the terminal device 110 is within the serving cell 123 of the access network device 121.

In case that the terminal device 110 is within the serving cell 123 of the access network device 121, the terminal device 110 may communicate with the access network device 121 via such as a service link or radio link. Communication in a direction from a terminal device 110 towards the access network device 121 is referred to as uplink communication, while communication in a reverse direction from the access network device 121 towards the terminal device 110 is referred to as downlink communication.

In addition, in the example of Fig. 1, both the terminal device 110 and the access network device 121 may move over time. When moving, the terminal device 110 may be located in different serving cells and also may be out of the coverage of the network sometimes.

In the example of Fig. 1, the terminal device 110 may be in different states (such as, connected state, inactive state and idle state) and also may operate on a power saving mechanism including but not limited to DRX, eDRX, PSM, relaxed monitoring and so on.

Further, the network environment 100 also comprises a CN 135. Further, the CN 135 may comprise a plurality of CN devices (such as, the CN device 130 as illustrated in Fig. 1) . The plurality of CN devices may implement any suitable functionality. The

access network devices

121 and 122 may connect to the CN device 130 via such as feeder links or radio links.

The communications in the communication environment 100 may conform to any suitable standards including, but not limited to, Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications 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) , 5.5G, 5G-Advanced networks, or the sixth generation (6G) communication protocols.

It is to be understood that the numbers and their connections of access network device, terminal device, CN device, CN and serving cell are only for the purpose of illustration without suggesting any limitations. The communication environment 100 may include any suitable access network device, terminal device, CN device, CN and serving cell adapted for implementing embodiments of the present disclosure. Although not shown, it is to be understood that one or more additional network devices may comprised in communication environment 100, such as, a terrestrial station, a gateway and so on.

EXAMPLE IMPLEMENTATION OF NEIGHBOR CELL MEASUREMENT BEFORE RLF

In this embodiment, a solution is provided to trigger a neighbor cell measurement before a RLF is detected. This will be described in connection with Figs. 2 and 3.

Fig. 2 illustrates a schematic diagram illustrating a process 200 for communication according to embodiments of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to Fig. 1. The process 200 may involve the terminal device 110 and the

access network devices

121 and 122 as illustrated in Fig. 1. Assuming that the access network device 121 provides a source cell (i.e., source serving cell) , and the access network device 122 provides a target cell (i.e., target serving cell) .

As shown in Fig. 2, the access network device 121 transmits 210, to the terminal device 110, a configuration indicating a condition for performing a neighbor cell measurement before a RLF is detected. In some embodiments, the condition may be set based on a quality of a serving cell (i.e., the source cell) of the access network device 121. In some embodiments, the condition may comprise the quality of the serving cell is lower than or equal to a threshold quality. For example, in some embodiments, the condition may comprise RSRP of the serving cell becomes lower than or equal to a threshold RSRP. In some embodiments, the condition may comprise RSRP of the serving cell becomes lower than or equal to threshold RSRP. In some embodiments, the condition may comprise a reference signal receiving quality (RSRQ) of the serving cell becomes lower than or equal to a threshold RSRQ. In some embodiments, the condition may comprise a signal to interference plus noise ratio (SINR) of the serving cell becomes lower than or equal to a threshold SINR. In some embodiments, the condition may comprise out-of-sync counting becomes greater than or equal to a threshold counting. Of course, these are merely examples, and any other suitable forms of the quality of the serving cell are also feasible.

In some embodiments, the condition may comprise a variance of the quality of the serving cell is lower than or equal to a threshold variance. For example, the condition may be represented as equation (1) below.

(SrxlevRef –Srxlev) ≤ SSearchDeltaP (1)

where Srxlev denotes current quality of the serving cell (dB) , SrxlevRef denotes reference quality of the serving cell (dB) , and SSearchDeltaP denotes the threshold variance.

In an example, after selecting or reselecting a new cell, or if (Srxlev -SrxlevRef) > 0, or if a relaxed monitoring criterion has not been met for threshold criterion (e.g., T _SearchDeltaP) , the terminal device 110 may set the value of SrxlevRef to the current Srxlev value of the serving cell. For example, T _SearchDeltaP = 5 minutes, or an eDRX cycle length if eDRX is configured and the eDRX cycle length is longer than 5 minutes.

In some embodiments, SSearchDeltaP may have a first value for an earth fixed cell and a second value for an earth moving cell. In some embodiments, the first value may be the same as the second value. In some embodiments, the first value may be different from the second value. For example, the second value may be greater than or equal to the first value, as represented by equation (2) below.

SSearchDeltaP_moving ≥ SSearchDeltaP_fix (2)

where SSearchDeltaP_moving denotes SSearchDeltaP for an earth moving cell, and SSearchDeltaP_fix denotes SSearchDeltaP for an earth fixed cell. In this way, a quality variance caused by the moving cell is considered.

In some embodiments, the condition may be set based on a location of the terminal device 110. For example, the condition may comprise a distance between the location of the terminal device 110 and a reference location is greater than or equal to a threshold distance. The reference location may be associated with the serving cell, and may be also referred to as serving cell’s reference location. As another example, the condition may comprise a variance of the distance between the location of the terminal device 110 and the reference location is greater than or equal to a predetermined value. For example, the predetermined value may be zero. In this case, the condition may be represented by equation (3) below.

d_t2 –d_t1 ≥ 0 (3)

where d_t2 denotes the distance between the location of the terminal device 110 and the reference location at time t2, and d_t1 denotes the distance between the location of the terminal device 110 and the reference location at time t1 earlier than time t2. It is to be understood that the predetermined value may also be any other suitable value, and the present disclosure does not limit this aspect.

In other words, if the equation (3) is true, the distance between the location of the terminal device 110 and the reference location is getting larger. It is to be understood that the equation (3) is merely an example, and any other suitable ways are also feasible for evaluating the variance of the distance between the location of the terminal device 110 and the reference location. For example, the terminal device 110 may determine a variance of the distance between the location of the terminal device 110 and the reference location in a predetermined time unit. That is, a time interval between the time t1 and t2 may be predetermined. For example, the predetermined time unit or interval may be 1min, 5min or a predetermined number of discontinuous reception (DRX) cycles. Of course, the predetermined time unit or interval may also adopt any other suitable forms.

In some embodiments, for an earth moving cell, the reference location may change as the moving of the coverage. In these embodiments, the terminal device 110 may adjust the reference location as (x+at, y+at) , where t denotes the time passed since a previous request for the reference location.

In some embodiments, the condition may be set based on both the quality of the serving cell and the location of the terminal device 110. In some embodiments, the condition may comprise: the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; and a distance between the location of the terminal device 110 and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell. In some embodiments, the condition may comprise: the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; and a variance of the distance between the location of the terminal device 110 and the reference location is greater than or equal to a predetermined value. It is to be understood that the predetermined value may be any suitable values, and the present disclosure does not limit this aspect.

In some embodiments, the condition may comprise: the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; a distance between the location of the terminal device 110 and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; and a variance of the quality of the serving cell is lower than or equal to a threshold variance; and a variance of the distance between the location of the terminal device 110 and the reference location is greater than or equal to a predetermined value. It is to be understood that the predetermined value may be any suitable values, and the present disclosure does not limit this aspect. Of course, these are merely examples, and any other suitable forms of the condition are also feasible.

With reference to Fig. 2, the terminal device 110 determines 220 whether the condition is satisfied. If the condition is satisfied, the terminal device 110 performs 230 a neighbor cell measurement. In this way, the terminal device 110 may perform a cell search so as to determine a target cell. It is to be understood that the neighbor cell measurement or the cell search may be implemented in any suitable ways, and the present disclosure does not limit this aspect.

In some embodiments, the terminal device 110 may determine 240 a value of a timer for RLF detection based on a type of the determined target cell. In other words, different values of the timer may be used to trigger RLF according to the type of the target cell.

In some embodiments, the type of the target cell may comprise a terrestrial network (TN) cell and a NTN cell. The NTN cell may comprise an earth fixed cell and an earth moving cell. In some embodiments, the timer may have a first value for the TN cell and a second value for the NTN cell. For example, the first value may be smaller than or equal to the second value. In some embodiments, the timer may have a third value for the earth fixed cell and a fourth value for the earth moving cell. For example, the third value may be smaller than or equal to the fourth value.

In some embodiments, the terminal device 110 may determine 250 whether the timer for RLF detection expires. For example, the timer may be T310. Of course, the timer may adopt any other suitable forms. If the timer for RLF detection expires, the terminal device 110 may determine 260 that a RLF is detected. Of course, any other suitable ways are also feasible for RLF detection.

Then the terminal device 110 may perform 270 a re-establishment for RRC connection to the target cell of the access network device 122. For example, the terminal device 110 may transmit 271 a request (for example, RRCConnectionReestablishmentRequest message) for RRC connection re-establishment to the access network device 122. The access network device 122 may transmit 272 a message (for example, RRCConnectionReestablishment message) indicating RRC connection re-establishment to the terminal device 110. Then the terminal device 110 may transmit 273, to the access network device 122, a response (for example, RRCConnectionReestablishmentComplete message) indicating that the RRC connection re-establishment is completed.

With the process 200, a neighbor cell measurement may be triggered before a RLF is detected. Fig. 3 illustrates a schematic diagram 300 illustrating an example timeline for a re-establishment of RRC connection according to embodiments of the present disclosure. As shown in Fig. 3, the terminal device 110 may determine whether a RLF is detected based on out-of-sync counting (for example, N310) . Meanwhile, the terminal device 110 may determine whether a criterion to start measurement is fulfilled during the RLF detection. That is, the terminal device 110 may determine whether the condition for performing the neighbor cell measurement as described above is satisfied. Based on the neighbor cell measurement, the terminal device 110 may determine the target cell, i.e., a proper neighbor cell is found. When a RLF is detected, the terminal device 110 may directly perform a RRC re-establishment to the target cell.

In this way, a neighbor cell measurement may be triggered before a RLF is detected, and thus the time taken for RRC re-establishment to a target cell may be reduced.

EXAMPLE IMPLEMENTATION OF CONDITIONAL RE-ESTABLISHMENT

In this embodiment, a solution of conditional re-establishment is provided. This will be described in connection with Fig. 4.

Fig. 4 illustrates a schematic diagram illustrating another process 400 for communication according to embodiments of the present disclosure. For the purpose of discussion, the process 400 will be described with reference to Fig. 1. The process 400 may involve the terminal device 110 and the

access network devices

As shown in Fig. 4, the access network device 121 transmits 410, to the terminal device 110, a configuration (for convenience, also referred to as a configuration for conditional re-establishment herein) indicating a condition for performing a re-establishment of a connection between the terminal device 110 and a target cell of a further access network device (for example, the access network device 122) . In some embodiments, the access network device 121 may transmit the configuration to the terminal device 110 via system information. In some embodiments, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling. For example, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling during RRC connection setup. As another example, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling during RRC reconfiguration, for example, for user plane (UP) solution.

In some embodiments, the condition for performing the re-establishment may be set based on a quality of a serving cell (i.e., the source cell) of the access network device 121. In some embodiments, the condition may comprise the quality of the serving cell is lower than or equal to a first threshold quality. For example, in some embodiments, the condition may comprise RSRP of the serving cell becomes lower than or equal to first threshold RSRP. In some embodiments, the condition may comprise a RSRQ of the serving cell becomes lower than or equal to a first threshold RSRQ. In some embodiments, the condition may comprise a SINR of the serving cell becomes lower than or equal to a first threshold SINR. In some embodiments, the condition may comprise out-of-sync counting becomes greater than or equal to a first threshold counting. In some embodiments, the condition may comprise a timer (for example, T310) of the serving cell for RLF detection expires. In some embodiments, the condition may comprise a variance of the quality of the serving cell is lower than or equal to a first threshold variance.

In some embodiments, the condition for performing the re-establishment may be set based on a quality of a target cell of the access network device 122. In some embodiments, the condition may comprise the quality of the target cell is lower than or equal to a second threshold quality. For example, in some embodiments, the condition may comprise RSRP of the target cell becomes lower than or equal to second threshold RSRP. In some embodiments, the condition may comprise a RSRQ of the target cell becomes lower than or equal to a second threshold RSRQ. In some embodiments, the condition may comprise a SINR of the target cell becomes lower than or equal to a second threshold SINR. In some embodiments, the condition may comprise a variance of the quality of the target cell is lower than or equal to a second threshold variance.

In some embodiments, the condition for performing the re-establishment may be set based on a location of the terminal device 110. In some embodiments, the location of the terminal device 110 may be determined based on a first reference location associated with the serving cell. For example, the condition may comprise a distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first threshold distance. As another example, the condition may comprise a variance of the distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first predetermined value. For example, the first predetermined value may be zero. Of course, the first predetermined value may be any other suitable value.

In some alternative embodiments, the location of the terminal device 110 may be determined based on a second reference location associated with the target cell. For example, the condition may comprise a distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second threshold distance. As another example, the condition may comprise a variance of the distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second predetermined value. For example, the second predetermined value may be zero. Of course, the second predetermined value may be any other suitable value.

In some embodiments, for an earth moving cell, the first or second reference location may change as the moving of the coverage. In these embodiments, the terminal device 110 may adjust the first or second reference location as (x+at, y+at) , where t denotes the time passed since a previous request for the first or second reference location.

It is to be understood that the condition for performing the re-establishment may be set based on any combination of the quality of the serving cell, the quality of the target cell, and the location of the terminal device 110. Of course, these are merely examples, and any other suitable forms of the condition are also feasible.

In some embodiments, the configuration may further indicate the target cell. In some embodiments, the target cell may be determined from one of neighbor cells according to the satellites moving trajectory in the ephemeris. In this case, the target cell is going to be the next serving cell.

In some embodiments, the configuration may further indicate a duration for which the condition for the re-establishment is satisfied. For example, the terminal device 110 may evaluate the condition for the re-establishment M times in the duration, and the terminal device 110 satisfies the condition N times (N≤M) . If N is greater than or equal to a predetermined value, the terminal device 110 may trigger the re-establishment. If N is smaller than the predetermined value, the terminal device 110 may not trigger the re-establishment. Of course, this is merely an example, and any other suitable ways are also feasible for the evaluation.

In some embodiments, the configuration may further indicate a duration (for convenience, also referred to as an evaluate duration) for evaluating the condition for the re-establishment. The evaluate duration indicates a valid time range the terminal device 110 can evaluate the condition for the re-establishment. In some embodiments, the evaluate duration may be indicated by a universal time coordinated (UTC) time and a predetermined duration or timer. For example, 00: 00: 01 + 40s. It is to be understood that the predetermined duration or timer may adopt any other suitable values. In some embodiments, the evaluate duration may be indicated by two UTC time indicating a starting time and an ending time of the target cell. For example, 00: 00: 01 + 00: 00: 41. In some embodiments, the evaluate duration may be indicated by a reference time and a predetermined duration or timer. For example, a system frame number (SFN) corresponding to the evaluate duration = 0 + 40s. In some embodiments, the evaluate duration may be indicated by two timers T1 and T2. For example, T1=301s, and T2=341s. It is to be understood that the two timers may adopt any other suitable values. For example, the timer T1 may start upon reception of the configuration or upon reception of an indication for activating the configuration. The timer T2 may start upon expiry of the timer T1. The evaluate duration may start upon expiry of the timer T1 and may end upon expiry of the timer T2. Of course, the evaluate duration may also be indicated by any other suitable ways.

In some embodiments, the configuration may further indicate a valid time of the configuration indicating the condition for the re-establishment. That is, the configuration becomes invalid when the valid time elapses. In some embodiments, the valid time may be indicated by a UTC time and a predetermined duration or timer. The UTC time is an absolute time value to indicate the starting of the valid time. The predetermined duration or timer is a time offset from the UTC time to indicate the valid time range allowing the terminal device 110 to trigger the re-establishment on the target cell. For example, 00: 00: 01 + 40s. It is to be understood that the predetermined duration or timer may adopt any other suitable values.

In some embodiments, the valid time may be indicated by two UTC time indicating a starting time (denoted as t1) and an ending time (denoted as t2) of the target cell. For example, 00: 00: 01 + 00: 00: 41. Time duration [t1, t2] is associated with a respective target cell. The terminal device 110 may perform the re-establishment to the target cell during the time duration. The Time t2 indicates the latest time when the terminal device 110 is allowed to trigger the re-establishment on the target cell.

In some embodiments, the valid time may be indicated by a reference time and a predetermined duration or timer. For example, a SFN corresponding to the valid time = 0 + 40s. In some embodiments, the valid time may be indicated by two timers T3 and T4. For example, T3=301s, and T4=341s. It is to be understood that the two timers may adopt any other suitable values. For example, the timer T3 may start upon reception of the configuration or upon reception of an indication for activating the configuration. The timer T4 may start upon expiry of the timer T3. The valid time may start upon expiry of the timer T3 and may end upon expiry of the timer T4. Of course, the valid time may also be indicated by any other suitable ways.

In some embodiments, the evaluation on the condition for the re-establishment may need to be triggered. In this way, evaluating all the time is avoided. With reference to Fig. 4, the terminal device 110 may receive 421, from the access network device 121, an indication indicating that the configuration for conditional re-establishment is to be activated. In some embodiments, the terminal device 110 may receive the indication via a medium access control (MAC) control element (CE) . In some embodiments, the terminal device 110 may receive the indication via downlink control information (DCI) . The reception of the indication means that the configuration for conditional re-establishment is enabled and the evaluation on the condition for the re-establishment is allowed to be started. In response to receiving the indication, the terminal device 110 may determine 430 whether the condition for the re-establishment is satisfied. Of course, the terminal device 110 may determine 430, without the indication, whether the condition for the re-establishment is satisfied.

In some embodiments, if the configuration for conditional re-establishment is received, the terminal device 110 may determine 430 whether the condition for the re-establishment is satisfied.

In some embodiments, the terminal device 110 may determine 422 whether the quality of the serving cell is lower than or equal to a threshold quality. If the quality of the serving cell is lower than or equal to a threshold quality, the terminal device 110 may determine 430 whether the condition for the re-establishment is satisfied.

In some embodiments, the terminal device 110 may determine 423 whether a predetermined time after the detection of RLF elapses. If the predetermined time elapses, the terminal device 110 may determines 430 whether the condition for the re-establishment is satisfied. In some embodiments, the predetermined time may be preconfigured or predefined. In some embodiments, the predetermined time may be equal to zero. In this case, if the RLF is detected, the terminal device 110 may immediately start the evaluation of the condition for the re-establishment.

In some embodiments, the terminal device 110 may determine 424 whether a duration for evaluating the condition for the re-establishment is configured. If the duration is configured, the terminal device 110 may determine 430 whether the condition for the re-establishment is satisfied during the configured duration.

In some embodiments, the terminal device 110 may receive 440, from the access network device 121, an indication indicating a value of a timer for RLF detection, the value being lower than or equal to a threshold value. That is, a shorter timer (for example, T310) may be used to trigger RLF earlier if the condition for the re-establishment is configured. This is advantageous especially in some scenarios where after several out-of-syncs, the channel condition may be too bad to do transmission and recovery probability may be very small due to the moving of the satellite.

With reference to Fig. 4, if the condition for the re-establishment is satisfied, the terminal device 110 performs 450 the re-establishment for RRC connection to the target cell of the access network device 122. For example, the terminal device 110 may transmit 451 a request (for example, RRCConnectionReestablishmentRequest message) for RRC connection re-establishment to the access network device 122. The access network device 122 may transmit 452 a message (for example, RRCConnectionReestablishment message) indicating RRC connection re-establishment to the terminal device 110. Then the terminal device 110 may transmit 453, to the access network device 122, a response (for example, RRCConnectionReestablishmentComplete message) indicating that the RRC connection re-establishment is completed.

With the process 400, a conditional re-establishment may be achieved. A target cell belonging to the next serving satellite is provided and thus the time taken for RRC re-establishment to the target cell is reduced.

EXAMPLE IMPLEMENTATION OF CONDITIONAL SUSPEND

In this embodiment, a solution of conditional suspend is provided. This will be described in connection with Fig. 5.

Fig. 5 illustrates a schematic diagram illustrating still another process 500 for communication according to embodiments of the present disclosure. For the purpose of discussion, the process 500 will be described with reference to Fig. 1. The process 500 may involve the terminal device 110, the

access network devices

121 and 122 and the core network device 130 as illustrated in Fig. 1. Assuming that the access network device 121 provides a source cell (i.e., source serving cell) , and the access network device 122 provides a target cell (i.e., target serving cell) .

As shown in Fig. 5, the access network device 121 transmits 410, to the terminal device 110, a configuration (for convenience, also referred to as a configuration for conditional suspend herein) indicating a condition for performing a suspending of the terminal device 110. In some embodiments, the access network device 121 may transmit the configuration to the terminal device 110 via system information. In some embodiments, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling. For example, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling during RRC connection setup. As another example, the access network device 121 may transmit the configuration to the terminal device 110 via a RRC signaling during RRC reconfiguration, for example, for UP solution.

In some embodiments, the condition for performing the suspending may be set based on a quality of a serving cell (i.e., the source cell) of the access network device 121. In some embodiments, the condition may comprise the quality of the serving cell is lower than or equal to a threshold quality. For example, in some embodiments, the condition may comprise RSRP of the serving cell becomes lower than or equal to threshold RSRP. In some embodiments, the condition may comprise a RSRQ of the serving cell becomes lower than or equal to a threshold RSRQ. In some embodiments, the condition may comprise a SINR of the serving cell becomes lower than or equal to a threshold SINR. In some embodiments, the condition may comprise out-of-sync counting becomes greater than or equal to a threshold counting. In some embodiments, the condition may comprise a timer (for example, T310) of the serving cell for RLF detection expires. In some embodiments, the condition may comprise a variance of the quality of the serving cell is lower than or equal to a threshold variance.

In some embodiments, the condition for performing the suspending may be set based on a location of the terminal device 110. In some embodiments, the location of the terminal device 110 may be determined based on a first reference location associated with the serving cell. For example, the condition may comprise a distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first threshold distance. As another example, the condition may comprise a variance of the distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first predetermined value. For example, the first predetermined value may be zero. Of course, the first predetermined value may be any other suitable value..

In some alternative embodiments, the location of the terminal device 110 may be determined based on a second reference location associated with a candidate cell. The candidate cell may be a neighbor cell or a configured target cell. For example, the condition may comprise a distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second threshold distance. As another example, the condition may comprise a variance of the distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second predetermined value. For example, the second predetermined value may be zero. Of course, the second predetermined value may be any other suitable value..

In some embodiments, the condition for performing the suspending may comprise a timer for the suspending. The terminal device 110 may perform the suspending when the timer expires. In some embodiments, the timer may be started upon the reception of the configuration of conditional suspend. In some embodiments, the timer may be started upon the reception of an indication for activating the configuration of conditional suspend.

It is to be understood that the condition for performing the suspending may be set based on any combination of the quality of the serving cell and the location of the terminal device 110. Of course, these are merely examples, and any other suitable forms of the condition are also feasible.

In some embodiments, the configuration may further comprise information of a resume identity (ID) . In some embodiments, the configuration may further indicate the target cell. For example, the target cell may be the next serving cell according to the satellite moving trajectory. In some embodiments, the terminal device 110 may resume to the target cell using the resume ID.

In some embodiments, the configuration may further indicate a duration for which the condition for the suspending is satisfied. For example, the terminal device 110 may evaluate the condition for the suspending M times in the duration, and the terminal device 110 satisfies the condition N times (N≤M) . If N is greater than or equal to a predetermined value, the terminal device 110 may trigger the suspending. If N is smaller than the predetermined value, the terminal device 110 may not trigger the suspending. Of course, this is merely an example, and any other suitable ways are also feasible for the evaluation.

In some embodiments, the configuration may further indicate a valid time of the configuration indicating the condition for the suspending. That is, the configuration becomes invalid when the valid time elapses. In some embodiments, the valid time may be indicated by a UTC time and a predetermined duration or timer. The UTC time is an absolute time value to indicate the starting of the valid time. The predetermined duration or timer is a time offset from the UTC time to indicate the valid time range allowing the terminal device 110 to trigger the suspending. For example, 00: 00: 01 + 40s. It is to be understood that the predetermined duration or timer may adopt any other suitable values.

In some embodiments, the valid time may be indicated by two UTC time indicating a starting time (denoted as t3) and an ending time (denoted as t4) of the suspending. For example, 00: 00: 01 + 00: 00: 41.

In some embodiments, the valid time may be indicated by a reference time and a predetermined duration or timer. For example, a SFN corresponding to the valid time = 0 + 40s. In some embodiments, the valid time may be indicated by two timers T5 and T6. For example, T5=301s, and T6=341s. It is to be understood that the two timers may adopt any other suitable values. For example, the timer T5 may start upon reception of the configuration or upon reception of an indication for activating the configuration. The timer T6 may start upon expiry of the timer T5. The valid time may start upon expiry of the timer T5 and may end upon expiry of the timer T6. Of course, the valid time may also be indicated by any other suitable ways.

In some embodiments, the configuration may further indicate a time (for convenience, also referred to as a resume time herein) after the suspending at which a resume is allowed to be triggered. In some embodiments, the resume time may be indicated by a UTC time and a predetermined duration or timer. The UTC time is an absolute time value to indicate the starting of the valid time. The predetermined duration or timer is a time offset from the UTC time to indicate the valid time range allowing the terminal device 110 to trigger RRC resume. For example, 00: 00: 01 + 40s. It is to be understood that the predetermined duration or timer may adopt any other suitable values.

In some embodiments, the resume time may be indicated by two UTC time indicating a starting time (denoted as t5) and an ending time (denoted as t6) of the suspending. For example, 00: 00: 01 + 00: 00: 41.

In some embodiments, the resume time may be indicated by a reference time and a predetermined duration or timer. For example, a SFN corresponding to the resume time =0 + 40s. In some embodiments, the resume time may be indicated by two timers T7 and T8. For example, T7=301s, and T8=341s. It is to be understood that the two timers may adopt any other suitable values. For example, the timer T7 may start upon reception of the configuration or upon reception of an indication for activating the configuration. The timer T8 may start upon expiry of the timer T7. The resume time may start upon expiry of the timer T7 and may end upon expiry of the timer T8. Of course, the resume time may also be indicated by any other suitable ways.

Return to Fig. 5, the access network device 121 may transmit 520, to the terminal device 110, an indication indicating that the configuration for conditional suspend is to be activated. In some embodiments, the access network device 121 may transmit the indication via a MAC CE. In some embodiments, the access network device 121 may transmit the indication via DCI.

In these embodiments, the access network device 121 may transmit 530, to the core network device 130, an indication indicating the configuration for conditional suspend or the activation of the configuration. For example, the access network device 121 may transmit S1-AP UE context suspend request to the core network device 130 and receive S1-AP UE context suspend response from the core network device 130. Based on the S1-AP UE context suspend request, the core network device 130 may know that the terminal device 110 is to be suspended, and thus may not release the context of the terminal device 110 upon transmission interrupt.

Upon reception of the indication, the terminal device 110 may determine 540 whether the condition for the suspending is satisfied. Of course, the terminal device 110 may determine 540, without the indication, whether the condition for the suspending is satisfied.

If the condition for the suspending is satisfied, the terminal device 110 suspends 550. That is, the terminal device 110 suspends without RRC release signaling. In this case, the terminal device 110 may leave a connected state (for example, RRC_CONNECTED state) . In some embodiments, the terminal device 110 may suspend a context of the terminal device 110 without releasing the context. The terminal device 110 may suspend radio bearers, for example, signaling radio bearer (SRB) 1 and all data radio bearers (DRBs) . The terminal device 110 may enter an idle state (for example, RRC_IDLE state) .

In some embodiments, the terminal device 110 may perform 560 a resume procedure according to the resume time. In some embodiments, the terminal device 110 may perform the resume procedure with a resume cause that indicates the suspending. For example, the resume cause may be “conditional suspend” or “early suspend” . Of course, any other suitable forms are also feasible. In some embodiments, if no resume procedure is initiated by the terminal device 110, the access network device 121 may notify the core network device 130 to release a context of the terminal device 110.

In some embodiments, if the resume time or the target cell is not configured, the terminal device 110 may initiate a resume procedure according to ephemeris obtained in a non-connected state or predicted satellite services. In these embodiments, the access network device 121 may maintain a timer. When the timer expires, the access network device 121 may notify the core network device 130 to release a context of the terminal device 110.

In some embodiments, the terminal device 110 may perform the resume procedure to the next cell (for example, the serving cell of the access network device 122) . For example, the terminal device 110 may transmit 561 a request (for example, RRCConnectionResumeRequest message) for RRC connection resume to the access network device 122. The access network device 122 may transmit 562 a message (for example, RRCConnectionResume message) indicating RRC connection resume to the terminal device 110. Then the terminal device 110 may transmit 563, to the access network device 122, a response (for example, RRCConnectionResumeComplete message) indicating that the RRC connection resume is completed.

With the process 500, a conditional suspend may be achieved. In this way, an unnecessary recovery procedure is avoided, and thus power consumption due to the unnecessary recovery procedure is reduced. In addition, suspend or release signaling is reduced.

EXAMPLE IMPLEMENTATION OF RLF RECOVERY TERMINATION UNDER NETWORK CONTROL

In this embodiment, solutions are provided for RLF recovery termination under network control. The detailed description will be given in connection with Embodiments 1 to 3 and with reference to Fig. 6.

Embodiment 1

This embodiment may be especially applied to the case in which a neighbor cell measurement is performed after RLF is detected. It is to be understood that this embodiment may also be applied to any other suitable scenarios.

Fig. 6 illustrates a schematic diagram illustrating yet another process 600 for communication according to embodiments of the present disclosure. For the purpose of discussion, the process 600 will be described with reference to Fig. 1. The process 600 may involve the terminal device 110 and the access network device 121 as illustrated in Fig. 1. Assuming that the access network device 121 provides a serving cell.

As shown in Fig. 6, the access network device 121 transmits 610, to the terminal device 110, an indication indicating that a recovery for a RLF is to be terminated. In some embodiments, the indication may be transmitted via a MAC CE. In some embodiments, the indication may be transmitted via DCI. In some embodiments, the indication may be transmitted via a RRC signaling. For example, the indication may be transmission via a RRC signaling during a RRC connection setup. As another example, the indication may be transmission via a RRC signaling during a RRC reconfiguration, especially for UP solution.

The terminal device 110 determines 611 whether a RLF is detected. If the RLF is detected, the terminal device 110 leaves 612 a connected state without RLF recovery. In other words, the terminal device 110 does not perform a cell search when a RLF is detected and leaves the connected state (for example, RRC_CONNECTED state) . In some embodiments, the terminal device 110 may enter a state in which normal idle mode procedures are stopped. For example, the normal idle mode procedures may comprise one or more of the following: performing a cell search, performing a measurement for cell re-selection, or monitoring a paging message.

In this way, an unnecessary recovery procedure is avoided, and thus power consumption due to the unnecessary recovery procedure is reduced.

Embodiment 2

This embodiment may be especially applied to the case in which a neighbor cell measurement is performed before RLF is detected. It is to be understood that this embodiment may also be applied to any other suitable scenarios.

Continue to with reference to Fig. 6, the access network device 121 transmits 620, to the terminal device 110, an indication indicating that a recovery for a RLF is to be terminated if a neighbor cell is unavailable before the RLF. In other words, if no proper neighbor cell is found before RLF, a RLF recovery is allowed to be terminated or disabled.

In some embodiments, the indication may be transmitted via a MAC CE. In some embodiments, the indication may be transmitted via DCI. In some embodiments, the indication may be transmitted via a RRC signaling. For example, the indication may be transmission via a RRC signaling during a RRC connection setup. As another example, the indication may be transmission via a RRC signaling during a RRC reconfiguration, especially for UP solution.

The terminal device 110 determines 621 whether a RLF is detected. If the RLF is detected, the terminal device 110 determines 622 whether a proper neighbor cell is found, i.e., whether a neighbor cell is available. If no neighbor cell is available, the terminal device 110 leaves 623 a connected state without RLF recovery. In other words, the terminal device 110 does not perform a cell search when a RLF is detected and leaves the connected state (for example, RRC_CONNECTED state) . In some embodiments, the terminal device 110 may enter a state in which normal idle mode procedures are stopped. For example, the normal idle mode procedures may comprise one or more of the following: performing a cell search, performing a measurement for cell re-selection, or monitoring a paging message.

If a neighbor cell (i.e., a target cell) is available, the terminal device 110 may perform 624 a re-establishment for a RRC connection to the target cell. In some embodiments, the target cell may be determined before the RLF. In some embodiments, the target cell may be determined after the RLF.

In this way, an unnecessary recovery procedure is also avoided, and thus power consumption due to the unnecessary recovery procedure is also reduced.

Embodiment 3

This embodiment may be especially applied to the case in which a conditional re-establishment is configured. It is to be understood that this embodiment may also be applied to any other suitable scenarios.

Continue to with reference to Fig. 6, the access network device 121 may transmit 630, to the terminal device 110, an indication that a RLF recovery is allowed to be terminated upon detection of a RLF. In some embodiments, the indication may be transmitted via a MAC CE. In some embodiments, the indication may be transmitted via DCI. In some embodiments, the indication may be transmitted via a RRC signaling. For example, the indication may be transmission via a RRC signaling during a RRC connection setup. As another example, the indication may be transmission via a RRC signaling during a RRC reconfiguration, especially for UP solution.

Based on the indication, the terminal device 110 may determine 631 that a RLF recovery is allowed to be terminated upon detection of a RLF. In this way, the RLF recovery termination is indicated in an explicit way.

In some alternative embodiments, if the terminal device 110 receives, from the access network device 121, the configuration for conditional re-establishment or an indication for activating the configuration, the terminal device 110 may determine 631 that a RLF recovery is allowed to be terminated upon detection of a RLF. In this way, the RLF recovery termination is indicated in an implicit way.

Then the terminal device 110 determines 632 whether the RLF is detected before the condition for the re-establishment is evaluated. For example, the terminal device 110 may determine whether the RLF is detected before the evaluate duration for the evaluation expires.

If the RLF is detected before the condition for the re-establishment is evaluated (for example, the RLF is detected before the evaluate duration starts) , the terminal device 110 leaves 633 a connected state (for example, RRC_CONNECTED state) . In some embodiments, the terminal device 110 may enter a state in which normal idle mode procedures are stopped. For example, the normal idle mode procedures may comprise one or more of the following: performing a cell search, performing a measurement for cell re-selection, or monitoring a paging message. In some embodiments, when the evaluate duration starts, the terminal device 110 may revert to evaluate the condition for the re-establishment.

It is to be understood that the above embodiments described in connection with Figs. 2 to 6 may be carried out separately or in any suitable combination.

EXAMPLE IMPLEMENTATION OF METHODS

Accordingly, embodiments of the present disclosure provide methods of communication implemented at a terminal device and an access network device. These methods will be described below with reference to Figs. 7 to 9.

Fig. 7 illustrates an example method 700 of communication implemented at a terminal device in accordance with some embodiments of the present disclosure. For example, the method 700 may be performed at the terminal device 110 as shown in Fig. 1. For the purpose of discussion, in the following, the method 700 will be described with reference to Fig. 1. It is to be understood that the method 700 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 710, the terminal device 110 receives, from a first access network device (for example, the access network device 121) , a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the access network device 121 or a location of the terminal device 110.

At block 720, the terminal device 110 determines whether the condition is satisfied. If the condition is satisfied, the process proceeds to block 730. At block 730, the terminal device 110 performs the operation.

In some embodiments, the operation may comprise a neighbor cell measurement before a RLF is detected. In these embodiments, the condition may comprise the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; and at least one of the following: a distance between the location of the terminal device 110 and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; or a variance of the distance between the location of the terminal device 110 and the reference location is greater than or equal to a predetermined value. In some embodiments, the threshold variance may have a first value for an earth fixed cell and a second value for an earth moving cell, the second value being greater than or equal to the first value.

In some embodiments where the operation comprises a neighbor cell measurement before a RLF is detected, the terminal device 110 may determine a target cell by performing a cell search based on the neighbor cell measurement, and determine, based on a type of the target cell, a value of a timer for detection of a RLF. In some embodiments, the type of the target cell may comprise at least one of a terrestrial network cell or a non-terrestrial network cell, and the non-terrestrial network cell may comprise at least one of an earth fixed cell or an earth moving cell.

In some embodiments, the timer may have a first value for the terrestrial network cell and a second value for the non-terrestrial network cell, the first value being smaller than or equal to the second value. In some embodiments, the timer has a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.

In some embodiments, the operation may comprise a re-establishment of a connection between the terminal device 110 and a target cell of a second access network device (for example, the access network device 122) . In these embodiments, the configuration may further indicate the target cell. In these embodiments, the condition may comprise at least one of the following: a distance between the location of the terminal device 110 and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell; a variance of a distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first predetermined value; a distance between the location of the terminal device 110 and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with the target cell; a variance of the distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second predetermined value; the quality of the serving cell is lower than or equal to a first threshold quality; a variance of the quality of the serving cell is lower than or equal to a first threshold variance; the quality of the target cell is lower than or equal to a second threshold quality; or a variance of the quality of the target cell is lower than or equal to a second threshold variance.

In some embodiments where the operation comprises the re-establishment, the configuration may further indicate at least one of the following: a duration for which the condition for the re-establishment is satisfied, a duration for evaluating the condition for the re-establishment, or a valid time of the configuration indicating the condition for the re-establishment.

In some embodiments where the operation comprises the re-establishment, the terminal device 110 may receive, from the access network device 121, an indication indicating that the configuration is to be activated, and determine, based on the indication, whether the condition for the re-establishment is satisfied.

In some embodiments where the operation comprises the re-establishment, if the quality of the serving cell is lower than or equal to a threshold quality, the terminal device 110 may determine whether the condition for the re-establishment is satisfied. In some embodiments, if a predetermined time after the detection of the RLF elapses, the terminal device 110 may determine whether the condition for the re-establishment is satisfied. In some embodiments, if a duration for evaluating the condition for the re-establishment is configured, the terminal device 110 may determine, within the duration, whether the condition for the re-establishment is satisfied.

In some embodiments where the operation comprises the re-establishment, the terminal device 110 may receive, from the access network device 121, an indication indicating a value of a timer for detection of the radio link failure, the value being lower than or equal to a threshold value.

In some embodiments, the operation may comprise a suspending of the terminal device 110. In these embodiments, the condition may comprise at least one of the following: a distance between the location of the terminal device 110 and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell; a variance of a distance between the location of the terminal device 110 and the first reference location is greater than or equal to a first predetermined value; a distance between the location of the terminal device 110 and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with a candidate cell; a variance of a distance between the location of the terminal device 110 and the second reference location is smaller than or equal to a second predetermined value; the quality of the serving cell is lower than or equal to a threshold quality; the variance of the quality of the serving cell is lower than or equal to a threshold variance; or a timer for the suspending. The terminal device 110 may perform the suspending when the timer expires. The timer may be started upon the reception of the configuration or upon reception of an indication for activating the configuration.

In some embodiments where the operation comprises the suspending of the terminal device 110, the configuration may further indicate at least one of the following: a duration for which the condition for the suspending is satisfied, a valid time of the configuration indicating the condition for the suspending, or a time after the suspending at which a resume is allowed to be triggered.

In some embodiments where the operation comprises the suspending of the terminal device 110, the terminal device 110 may receive, from the access network device 121, an indication indicating that the configuration is to be activated, and determine, based on the indication, whether the condition for the suspend is satisfied. In some embodiments, information of a resume identity may be comprised in the configuration or in the indication.

In some embodiments where the operation comprises the suspending of the terminal device 110, the terminal device 110 may perform a resume procedure with a resume cause that indicates the suspending.

In some embodiments, the terminal device 110 may receive, from the access network device 121, an indication indicating that a recovery for a RLF is to be terminated. If the RLF is detected, the terminal device 110 may leave a connected state.

In some embodiments, the terminal device 110 may receive, from the access network device 121, an indication indicating that a recovery for a RLF is to be terminated if a neighbor cell is unavailable before the RLF. If determining that no neighbor cell is available upon detection of the RLF, the terminal device 110 may leave a connected state.

In some embodiments where the operation comprises the re-establishment, if the RLF is detected before the condition for the re-establishment is evaluated, the terminal device 110 may leave a connected state. In some embodiments where the operation comprises the re-establishment, if an indication indicating that the configuration is to be activated is received and the RLF is detected before the condition for the re-establishment is evaluated, the terminal device 110 may leave a connected state.

With the method 700, a time taken for a RRC reestablishment to another cell may be reduced. Further, power consumption due to unnecessary recovery procedure may be reduced and related suspend signaling may be reduced.

Fig. 8 illustrates an example method 800 of communication implemented at an access network device in accordance with some embodiments of the present disclosure. For example, the method 800 may be performed at the

access network device

121 or 122 as shown in Fig. 1. For the purpose of discussion, in the following, the method 800 will be described with reference to Fig. 1. It is to be understood that the method 800 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 810, a first access network device (for example, the access network device 121) transmits, to the terminal device 110, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the access network device 121 or a location of the terminal device 110.

In some embodiments where the operation comprises a neighbor cell measurement before a RLF is detected, the access network device 121 may transmit, to the terminal device 110, a configuration for a timer for detection of a RLF, the timer having a first value for the TN cell and a second value for the NTN cell, the first value being smaller than or equal to the second value.

In some embodiments where the operation comprises a neighbor cell measurement before a RLF is detected, the access network device 121 may transmit, to the terminal device 110, a configuration for a timer for detection of a RLF, the timer having a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.

In some embodiments where the operation comprises the re-establishment, the access network device 121 may transmit, to the terminal device 110, an indication indicating that the configuration is to be activated.

In some embodiments where the operation comprises the re-establishment, the access network device 121 may determine a value of a timer for detection of the RLF, the value being lower than or equal to a threshold value, and indicate the value of the timer to the terminal device 110.

In some embodiments where the operation comprises the suspending of the terminal device 110, the access network device 121 may transmit, to the terminal device 110, an indication indicating that the configuration is to be activated. In some embodiments, information of a resume identity may be comprised in the configuration or in the indication. In some embodiments, the access network device 121 may transmit, to a core network device (for example, the core network device 130) , an indication indicating the configuration for the suspending or the activation of the configuration. In this way, the core network device 130 may be indicated to suspend the context of the terminal device 110.

In some embodiments where the operation comprises the suspending of the terminal device 110, the access network device 121 may transmit, to the terminal device 110, an indication indicating that a recovery for a RLF is to be terminated. In some embodiments, the access network device 121 may transmit, to the terminal device 110, an indication indicating that a recovery for a RLF is to be terminated if a neighbor cell is unavailable before the RLF.

With the method 800, a time taken for a RRC reestablishment to another cell may be reduced. Further, power consumption due to unnecessary recovery procedure may be reduced and related suspend signaling may be reduced.

EXAMPLE IMPLEMENTATION OF DEVICE AND APPARATUS

Fig. 9 is a simplified block diagram of a device 900 that is suitable for implementing embodiments of the present disclosure. The device 900 can be considered as a further example implementation of the terminal device 110 or the

access network device

121 or 122 as shown in FIG. 1. Accordingly, the device 900 can be implemented at or as at least a part of the terminal device 110 or the

access network device

121 or 122.

As shown, the device 900 includes a processor 910, a memory 920 coupled to the processor 910, a suitable transmitter (TX) and receiver (RX) 940 coupled to the processor 910, and a communication interface coupled to the TX/RX 940. The memory 910 stores at least a part of a program 930. The TX/RX 940 is for bidirectional communications. The TX/RX 940 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 930 is assumed to include program instructions that, when executed by the associated processor 910, enable the device 900 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 2 to 8. The embodiments herein may be implemented by computer software executable by the processor 910 of the device 900, or by hardware, or by a combination of software and hardware. The processor 910 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 910 and memory 920 may form processing means 950 adapted to implement various embodiments of the present disclosure.

The memory 920 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 920 is shown in the device 900, there may be several physically distinct memory modules in the device 900. The processor 910 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 900 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.

In some embodiments, a terminal device comprises a circuitry configured to: receive, from a first access network device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the first access network device or a location of the terminal device; and in accordance with a determination that the condition is satisfied, perform the operation, the operation comprising: a neighbor cell measurement before a radio link failure is detected, a re-establishment of a connection between the terminal device and a target cell of a second access network device, or a suspending of the terminal device.

In some embodiments, the operation comprises the neighbor cell measurement, and wherein the condition comprises: the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; and at least one of the following: a distance between the location of the terminal device and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; or a variance of the distance between the location of the terminal device and the reference location is greater than or equal to a predetermined value. In some embodiments, the threshold variance has a first value for an earth fixed cell and a second value for an earth moving cell, the second value being greater than or equal to the first value.

In some embodiments, the circuitry may be further configured to: determine a target cell by performing a cell search based on the neighbor cell measurement; and determine, based on a type of the target cell, a value of a timer for detection of a radio link failure. In some embodiments, the type of the target cell comprises at least one of a terrestrial network cell or a non-terrestrial network cell, the non-terrestrial network cell comprising at least one of an earth fixed cell or an earth moving cell. In some embodiments, the timer has a first value for the terrestrial network cell and a second value for the non-terrestrial network cell, the first value being smaller than or equal to the second value. In some embodiments, the timer has a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.

In some embodiments where the operation comprises the re-establishment, the configuration further indicates the target cell. In these embodiments, the condition comprises at least one of the following: a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell; a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value; a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with the target cell; a variance of the distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value; the quality of the serving cell is lower than or equal to a first threshold quality; a variance of the quality of the serving cell is lower than or equal to a first threshold variance; the quality of the target cell is lower than or equal to a second threshold quality; or a variance of the quality of the target cell is lower than or equal to a second threshold variance.

In some embodiments, the configuration further indicates at least one of the following: a duration for which the condition for the re-establishment is satisfied, a duration for evaluating the condition for the re-establishment, or a valid time of the configuration indicating the condition for the re-establishment.

In some embodiments, the circuitry may be further configured to: receive, from the first access network device, an indication indicating that the configuration is to be activated; and determine, based on the indication, whether the condition for the re-establishment is satisfied.

In some embodiments, the circuitry may be further configured to at least one of the following: in accordance with a determination that the quality of the serving cell is lower than or equal to a threshold quality, determine whether the condition for the re-establishment is satisfied; in accordance with a determination that a predetermined time after the detection of the radio link failure elapses, determine whether the condition for the re-establishment is satisfied; or in accordance with a determination that a duration for evaluating the condition for the re-establishment is configured, determine, within the duration, whether the condition for the re-establishment is satisfied.

In some embodiments, the circuitry may be further configured to: receive, from the first access network device, an indication indicating a value of a timer for detection of the radio link failure, the value being lower than or equal to a threshold value.

In some embodiments, the operation comprises the suspending. In these embodiments, the condition comprises at least one of the following: a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell; a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value; a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with a candidate cell; a variance of a distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value; the quality of the serving cell is lower than or equal to a threshold quality; the variance of the quality of the serving cell is lower than or equal to a threshold variance; or a timer for the suspending, performing the suspending by the terminal device while the timer expires, the timer being started upon the reception of the configuration or upon reception of an indication for activating the configuration.

In some embodiments where the operation comprises the suspending, the configuration further indicates at least one of the following: a duration for which the condition for the suspending is satisfied, a valid time of the configuration indicating the condition for the suspending, or a time after the suspending at which a resume is allowed to be triggered.

In some embodiments where the operation comprises the suspending, the circuitry may be further configured to: receive, from the first access network device, an indication indicating that the configuration is to be activated; and determine, based on the indication, whether the condition for the suspend is satisfied. In some embodiments, information of a resume identity is comprised in the configuration or in the indication.

In some embodiments where the operation comprises the suspending, the circuitry may be further configured to: perform a resume procedure with a resume cause that indicates the suspending.

In some embodiments, the circuitry may be further configured to: receive, from the first access network device, an indication indicating that a recovery for a radio link failure is to be terminated; and in response to detecting the radio link failure, leave a connected state.

In some embodiments, the circuitry may be further configured to: receive, from the first access network device, an indication indicating that a recovery for a radio link failure is to be terminated if a neighbor cell is unavailable before the radio link failure; and in response to determining that no neighbor cell is available upon detection of the radio link failure, leave a connected state.

In some embodiments where the operation comprises the re-establishment, the circuitry may be further configured to: in response to detecting the radio link failure before the condition for the re-establishment is evaluated, leave a connected state; or in response to receiving an indication indicating that the configuration is to be activated and in response to detecting the radio link failure before the condition for the re-establishment is evaluated, leave a connected state.

In some embodiments, a first access network device comprises a circuitry configured to: transmit, to a terminal device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the first access network device or a location of the terminal device, the operation comprising: a neighbor cell measurement before a radio link failure is detected, a re-establishment of a connection of the terminal device to a target cell of a second access network device, or a suspending of a context of the terminal device.

In some embodiments, the operation comprises the neighbor cell measurement. In these embodiments, the condition comprises: the quality of the serving cell is lower than or equal to a threshold quality; a variance of the quality of the serving cell is lower than or equal to a threshold variance; and at least one of the following: a distance between the location of the terminal device and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; or a variance of the distance between the location of the terminal device and the reference location is greater than or equal to a predetermined value. In some embodiments, the threshold variance has a first value for an earth fixed cell and a second value for an earth moving cell, the second value being greater than or equal to the first value.

In some embodiments, the circuitry may be further configured to: transmit, to the terminal device, a configuration for a timer for detection of a radio link failure, the timer having a first value for the terrestrial network cell and a second value for the non-terrestrial network cell, the first value being smaller than or equal to the second value.

In some embodiments, the circuitry may be further configured to: transmit, to the terminal device, a configuration for a timer for detection of a radio link failure, the timer having a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.

In some embodiments, the operation comprises the re-establishment and the configuration further indicates the target cell. In these embodiments, the condition comprises at least one of the following: a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell; a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value; a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with the target cell; a variance of the distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value; the quality of the serving cell is lower than or equal to a first threshold quality; the variance of the quality of the serving cell is lower than or equal to a first threshold variance; the quality of the target cell is lower than or equal to a second threshold quality; or the variance of the quality of the target cell is lower than or equal to a second threshold variance.

In some embodiments, the circuitry may be further configured to: transmit, to the terminal device, an indication indicating that the configuration indicating the condition for performing the re-establishment is to be activated.

In some embodiments, the circuitry may be further configured to: determine a value of a timer for detection of the radio link failure, the value being lower than or equal to a threshold value; and indicate the value of the timer to the terminal device.

In some embodiments where the operation comprises the suspending, the circuitry may be further configured to: transmit, to the terminal device, an indication indicating that the configuration indicating the condition for performing the suspend is to be activated.

In some embodiments, the circuitry may be further configured to: transmit, to a core network device, an indication indicating the configuration for the suspending or the activation of the configuration. In some embodiments, information of a resume identity is comprised in the configuration or in the indication.

In some embodiments, the circuitry may be further configured to: transmit, to the terminal device, an indication indicating that a recovery for a radio link failure is to be terminated; or transmit, to the terminal device, an indication indicating that a recovery for a radio link failure is to be terminated if a neighbor cell is unavailable before the radio link failure.

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.

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. 2 to 8. 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 method of communication, comprising:

receiving, at a terminal device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of a first access network device or a location of the terminal device; and

in accordance with a determination that the condition is satisfied, performing the operation, the operation comprising:

a neighbor cell measurement before a radio link failure is detected,

a re-establishment of a connection between the terminal device and a target cell of a second access network device, or

a suspending of the terminal device.
The method of claim 1, wherein the operation comprises the neighbor cell measurement, and wherein the condition comprises:

the quality of the serving cell is lower than or equal to a threshold quality;

a variance of the quality of the serving cell is lower than or equal to a threshold variance; and at least one of the following:

a distance between the location of the terminal device and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; or

a variance of the distance between the location of the terminal device and the reference location is greater than or equal to a predetermined value.
The method of claim 2, wherein the threshold variance has a first value for an earth fixed cell and a second value for an earth moving cell, the second value being greater than or equal to the first value.
The method of claim 2, further comprising:

determining a target cell by performing a cell search based on the neighbor cell measurement; and

determining, based on a type of the target cell, a value of a timer for detection of a radio link failure.
The method of claim 4, wherein the type of the target cell comprises at least one of a terrestrial network cell or a non-terrestrial network cell, the non-terrestrial network cell comprising at least one of an earth fixed cell or an earth moving cell.
The method of claim 5, wherein the timer has a first value for the terrestrial network cell and a second value for the non-terrestrial network cell, the first value being smaller than or equal to the second value.
The method of claim 5, wherein the timer has a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.
The method of claim 1, wherein the operation comprises the re-establishment and the configuration further indicates the target cell, and wherein the condition comprises at least one of the following:

a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell;

a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value;

a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with the target cell;

a variance of the distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value;

the quality of the serving cell is lower than or equal to a first threshold quality;

a variance of the quality of the serving cell is lower than or equal to a first threshold variance;

the quality of the target cell is lower than or equal to a second threshold quality; or

a variance of the quality of the target cell is lower than or equal to a second threshold variance.
The method of claim 8, wherein the configuration further indicates at least one of the following:

a duration for which the condition for the re-establishment is satisfied,

a duration for evaluating the condition for the re-establishment, or

a valid time of the configuration indicating the condition for the re-establishment.
The method of claim 8, further comprising:

receiving an indication indicating that the configuration is to be activated; and

determining, based on the indication, whether the condition for the re-establishment is satisfied.
The method of claim 8, further comprising at least one of the following:

in accordance with a determination that the quality of the serving cell is lower than or equal to a threshold quality, determining whether the condition for the re-establishment is satisfied;

in accordance with a determination that a predetermined time after the detection of the radio link failure elapses, determining whether the condition for the re-establishment is satisfied; or

in accordance with a determination that a duration for evaluating the condition for the re-establishment is configured, determining, within the duration, whether the condition for the re-establishment is satisfied.
The method of claim 8, further comprising:

receiving an indication indicating a value of a timer for detection of the radio link failure, the value being lower than or equal to a threshold value.
The method of claim 1, wherein the operation comprises the suspending, and wherein the condition comprises at least one of the following:

a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell;

a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value;

a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with a candidate cell;

a variance of a distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value;

the quality of the serving cell is lower than or equal to a threshold quality;

the variance of the quality of the serving cell is lower than or equal to a threshold variance; or

a timer for the suspending, performing the suspending by the terminal device while the timer expires, the timer being started upon the reception of the configuration or upon reception of an indication for activating the configuration.
The method of claim 13, wherein the configuration further indicates at least one of the following:

a duration for which the condition for the suspending is satisfied,

a valid time of the configuration indicating the condition for the suspending, or

a time after the suspending at which a resume is allowed to be triggered.
The method of claim 13, further comprising:

receiving an indication indicating that the configuration is to be activated; and

determining, based on the indication, whether the condition for the suspend is satisfied.
The method of claim 15, wherein information of a resume identity is comprised in the configuration or in the indication.
The method of claim 13, further comprising:

performing a resume procedure with a resume cause that indicates the suspending.
The method of claim 1, further comprising:

receiving an indication indicating that a recovery for a radio link failure is to be terminated; and

in response to detecting the radio link failure, leaving a connected state.
The method of claim 1, further comprising:

receiving an indication indicating that a recovery for a radio link failure is to be terminated if a neighbor cell is unavailable before the radio link failure; and

in response to determining that no neighbor cell is available upon detection of the radio link failure, leaving a connected state.
The method of claim 1, wherein the operation comprises the re-establishment, and wherein the method further comprises:

in response to detecting the radio link failure before the condition for the re-establishment is evaluated, leaving a connected state; or

in response to receiving an indication indicating that the configuration is to be activated and in response to detecting the radio link failure before the condition for the re-establishment is evaluated, leaving a connected state.
A method of communication, comprising:

transmitting, at a first access network device, a configuration indicating a condition for performing an operation, the condition being based on at least one of a quality of a serving cell of the first access network device or a location of a terminal device, the operation comprising:

a neighbor cell measurement before a radio link failure is detected,

a re-establishment of a connection of the terminal device to a target cell of a second access network device, or

a suspending of a context of the terminal device.
The method of claim 21, wherein the operation comprises the neighbor cell measurement, and wherein the condition comprises:

the quality of the serving cell is lower than or equal to a threshold quality;

a variance of the quality of the serving cell is lower than or equal to a threshold variance; and at least one of the following:

a distance between the location of the terminal device and a reference location is greater than or equal to a threshold distance, the reference location being associated with the serving cell; or

a variance of the distance between the location of the terminal device and the reference location is greater than or equal to a predetermined value.
The method of claim 22, wherein the threshold variance has a first value for an earth fixed cell and a second value for an earth moving cell, the second value being greater than or equal to the first value.
The method of claim 22, further comprising:

transmitting a configuration for a timer for detection of a radio link failure, the timer having a first value for the terrestrial network cell and a second value for the non-terrestrial network cell, the first value being smaller than or equal to the second value.
The method of claim 22, further comprising:

transmitting a configuration for a timer for detection of a radio link failure, the timer having a third value for the earth fixed cell and a fourth value for the earth moving cell, the third value being smaller than or equal to the fourth value.
The method of claim 21, wherein the operation comprises the re-establishment and the configuration further indicates the target cell, and wherein the condition comprises at least one of the following:

a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell;

a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value;

a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, the second reference location being associated with the target cell;

a variance of the distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value;

the quality of the serving cell is lower than or equal to a first threshold quality;

the variance of the quality of the serving cell is lower than or equal to a first threshold variance;

the quality of the target cell is lower than or equal to a second threshold quality; or

the variance of the quality of the target cell is lower than or equal to a second threshold variance.
The method of claim 26, wherein the configuration further indicates at least one of the following:

a duration for which the condition for the re-establishment is satisfied,

a duration for evaluating the condition for the re-establishment, or

a valid time of the configuration indicating the condition for the re-establishment.
The method of claim 26, further comprising:

transmitting an indication indicating that the configuration indicating the condition for performing the re-establishment is to be activated.
The method of claim 26, further comprising:

determining a value of a timer for detection of the radio link failure, the value being lower than or equal to a threshold value; and

indicating the value of the timer to the terminal device.
The method of claim 21, wherein the operation comprises the suspending, and wherein the condition comprises at least one of the following:

a distance between the location of the terminal device and a first reference location is greater than or equal to a first threshold distance, the first reference location being associated with the serving cell;

a variance of a distance between the location of the terminal device and the first reference location is greater than or equal to a first predetermined value;

a distance between the location of the terminal device and a second reference location is smaller than or equal to a second threshold distance, , the second reference location being associated with a candidate cell;

a variance of a distance between the location of the terminal device and the second reference location is smaller than or equal to a second predetermined value;

the quality of the serving cell is lower than or equal to a threshold quality;

the variance of the quality of the serving cell is lower than or equal to a threshold variance; or

a timer for the suspending, performing the suspending by the terminal device while the timer expires, the timer being started upon the reception of the configuration or upon reception of an indication for activating the configuration.
The method of claim 30, wherein the configuration further indicates at least one of the following:

a duration for which the condition for the suspending is satisfied,

a valid time of the configuration indicating the condition for the suspending, or

a time after the suspending at which a resume is allowed to be triggered.
The method of claim 30, further comprising:

transmitting an indication indicating that the configuration indicating the condition for performing the suspend is to be activated.
The method of claim 32, further comprising:

transmitting an indication indicating the configuration for the suspending or the activation of the configuration.
The method of claim 33, wherein information of a resume identity is comprised in the configuration or in the indication.
The method of claim 21, further comprising:

transmitting an indication indicating that a recovery for a radio link failure is to be terminated; or

transmitting an indication indicating that a recovery for a radio link failure is to be terminated if a neighbor cell is unavailable before the radio link failure.
A device of communication comprising:

a processor configured to perform the method according to any of claims 1-20.
A device of communication comprising:

a processor configured to perform the method according to any of claims 21-35.