WO2025030403A1

WO2025030403A1 - Timing advance reporting

Info

Publication number: WO2025030403A1
Application number: PCT/CN2023/111851
Authority: WO
Inventors: Ping Yuan; Ping Ping WEN; Jedrzej STANCZAK
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2023-08-08
Filing date: 2023-08-08
Publication date: 2025-02-13
Anticipated expiration: 2026-02-08
Also published as: CN119485618A

Abstract

Example embodiments of the present disclosure relate to methods, devices, apparatuses and computer readable storage medium for timing advance reporting. In a method, a first apparatus determines a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device. The source non-terrestrial network device serves the first apparatus. The target non-terrestrial network device provides a service to the first apparatus after the switching. The first apparatus transmits, to a second apparatus, information about the predicted timing advance before the switching.

Description

TIMING ADVANCE REPORTING

FIELDS

Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for timing advance (TA) reporting.

BACKGROUND

Non-terrestrial communications can be in a complementary manner to terrestrial deployments where satellite connectivity can provide coverage beyond terrestrial deployments. In a non-terrestrial network (NTN) system, fifth generation (5G) base stations (gNB) or gNB functionality are deployed on board satellites or relayed by gNBs in a transparent way to provide communication coverage over a very large area that may be otherwise unreachable by cellular networks.

In the NTN, cells originating from different satellites are associated with different physical cell identifications (PCIs) . A stationary user equipment (UE) may thus experience continuous layer 3 (L3) mobility as the serving satellite moves out of coverage and a new satellite takes over coverage of the geographic area. Unchanged PCI after satellite switching has been proposed with the goal of reducing the signaling overhead and simplifying radio resource control (RRC) procedures for the UE.

SUMMARY

In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus to: determine a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and transmit, to a second apparatus, information about the predicted timing advance before the switching.

In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus to: receive, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and determine, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.

In a third aspect of the present disclosure, there is provided a method. The method comprises: determining, at a first apparatus, a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and transmitting, to a second apparatus, information about the predicted timing advance before the switching.

In a fourth aspect of the present disclosure, there is provided a method. The method comprises: receiving, , at a second apparatus from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and determining, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.

In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for determining a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and means for transmitting, to a second apparatus, information about the predicted timing advance before the switching.

In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for receiving, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and means for determining, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.

In a seventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the third aspect or the fourth aspect.

It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

FIG. 2 illustrates a signaling diagram for timing advance reporting according to some example embodiments of the present disclosure;

FIG. 3 illustrates an example diagram showing time points for transmission according to some example embodiments of the present disclosure;

FIG. 4A and FIG. 4B illustrate example medium access control control element (MAC CE) formats for timing advance reporting according to some example embodiments of the present disclosure, respectively;

FIG. 5 illustrates an example diagram showing scheduling time relationship according to some example embodiments of the present disclosure;

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

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

FIG. 8 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 9 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

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

DETAILED DESCRIPTION

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

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

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, ” “second, ” …, etc. in front of noun (s) and the like 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 and they do not limit the order of the noun (s) . 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.

As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

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.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

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

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

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) , 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 “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , an NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

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

As briefly mentioned, in an NTN system, 5G base stations (gNB) or gNB functionality are deployed on board satellites or relayed by gNBs in a transparent way to provide communication coverage over a very large area. In some mechanisms, enhancements for both NTN-NTN and NTN-terrestrial network (TN) mobility and service continuity are proposed. For example, methods from new radio (NR) TN to NR NTN as baseline for further enhancements may include specifying NTN-NTN handover enhancement for RRC_CONNECTED UEs in the quasi-earth-fixed cell and earth-moving cell to reduce the signalling overhead.

In an NTN, cells originating from different satellites are associated with different PCIs. A stationary UE may thus experience continuous layer 3 (L3) mobility as the serving satellite moves out of coverage and a new satellite takes over coverage of the geographic area.

In some mechanisms, after the target satellite start providing coverage, the UE may obtain downlink (DL) synchronization by reading the synchronization signal block (SSB) provided by the target satellite. For UL synchronization, the most straightforward way is to perform random access channel (RACH) to acquire uplink (UL) synchronization. It is obvious that contention based random access (CBRA) may be one option to get the UL sync. Contention free random access (CFRA) may also be supported which needs to provide the dedicate RACH resource for UE before the satellite switching happens.

RACH-less handover in inter-satellite handover with same gateway/gNB is supported. The unchanged PCI scenario without handover is similar as the scenario of RACH-less inter-satellite handover with same gateway/gNB. That is, RACH-less may also be supported for unchanged PCI scenario. It means that UE may have valid TA of the target cell after inter-satellite switch without RACH. The issue of how to acquire TA of the target cell may need further discussion.

After satellite switch and UE re-synchronized to the serving cell (via target satellite) , NW will continue to schedule the UE for UL transmission, either with pre-allocated resource or dynamic granted resource.

In some mechanisms, unchanged PCI has been proposed with the goal of reducing the signaling overhead and simplifying radio resource control (RRC) procedures for the UE. UE getting UL sync without RACH in unchanged PCI without handover scenario may be supported.

In some mechanisms, CBRA/CFRA procedure can be used for UE to re-acquire UL synchronization to the target satellite in PCI unchanged scenario without handover. NTN RACH-less handover (HO) may be supported for Intra-satellite handover with the same feeder link. i.e., with same gateway/gNB. NTN RACH-less HO may be supported for intra-satellite handover with different feeder links, i.e., with gateway/gNB switch, inter-satellite handover with gateway/gNB switch, and inter-satellite handover with same gateway/gNB.

Some agreements related to unchanged PCI solution were discussed. In quasi-earth fixed cell case, for hard satellite switch with the same synchronization signal block (SSB) frequency and same gNB (no security key change) , satellite switching without PCI changing (not requiring L3 mobility) is supported.

In the third-generation partnership project (3GPP) Rel-18, the focus is on transparent architecture and the most obvious case is when the cells are provided by the same gNB, i.e., the same cell with the fixed PCI is provided by the same gNB. In this case, only the satellite node is changed. However, theoretically, this could also work with different gNB and potentially even for the regenerative case.

In some mechanisms, how to perform synchronization to the serving cell after satellite switch is proposed. For example, it is proposed to support UE getting UL sync (to the serving cell after satellite switch) without random access channel (RACH) in unchanged PCI (without handover) scenario.

In the unchanged PCI scenario, the satellite will be switched without L3 mobility procedure (e.g., handover) . When the RACH-less procedure is combined with the PCI unchanged solution, the UE maybe sync-up to target satellite without RACH. After the switching, the NW continues to schedule the UE either dynamically or via pre-allocated resource. In hard switch unchanged PCI scenario (i.e., no handover) , the UE needs to know the time the UE attempts to re-synchronize.

However, when the satellite switch happens, the UE may experience TA jump issue. When the TA jump happens after the satellite switch, if the network (NW) doesn’t know the new TA targeted to the new satellite, the physical uplink shared channel (PUSCH) transmission to the target satellite may be failed. The reason is that, to guarantee UL transmission the NW configured Koffset should meet Koffset > TA + UL processing delay –4, while it may not be satisfied when the TA jump happened. For example, when the TA is increased by 10 ms after the switch while NW does not adjust the Koffset accordingly due to lack of new TA information, the UE cannot perform UL transmission due to outdated Koffset.

In addition, if the NW knows the time of satellite switch and use the largest UE-eNB RTT among all UEs) on the scheduling, the scheduling latency will be increased.

In order to solve at least part of the above problems or other potential problems, a solution on timing advance (TA) reporting is proposed. According to example embodiments, a first apparatus (such as a terminal device) determines a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device. The source non-terrestrial network device serves the first apparatus. The target non-terrestrial network device is to provide a service to the first apparatus after the switching. The first apparatus transmits, to a second apparatus (such as a network device) , information about the predicted timing advance before satellite switching.

In this way, the second apparatus can be informed of the new predicted TA. With the new predicted TA, the second apparatus can continue the scheduling in the serving cell after the switching.

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

FIG. 1A illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. In the communication environment 100, a first apparatus110 and a second apparatus 120 can communicate with each other through a non-terrestrial network (NTN) device 130. In some example embodiments, the NTN device 130 may be a satellite or a high-altitude platform station (HAPS) . The second apparatus 120 may communicate with a data network 140.

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

In some example embodiments, if the second apparatus 120 is a network device, it may be a gNB connected to the NTN device 130 (in transparent architecture) , or a gNB located in the NTN device 130 (in regenerate architecture) .

In some example embodiments, if the first apparatus 110 is a terminal device and the second apparatus 120 is a network device, a link 134 between the second apparatus 120 and the satellite 130 may be referred to as a feeder link, and a link 132 between the satellite 130 and the first apparatus 110 may be referred to as a service link.

In some example embodiments, the first apparatus 110 is located in a serving area or a coverage of the NTN device 130. For example, the first apparatus 110 may be located in different beam foot points.

In some example embodiments, if the first apparatus 110 is a terminal device and the second apparatus 120 is a network device, a link from the second apparatus 120 to the first apparatus 110 is referred to as a downlink (DL) , while a link from the first apparatus 110 to the second apparatus 120 is referred to as an uplink (UL) . In DL, the second apparatus 120 is a transmitting (TX) device (or a transmitter) and the first apparatus 110 is a receiving (RX) device (or a receiver) . In UL, the first apparatus 110 is a TX device (or a transmitter) and the second apparatus 120 is a RX device (or a receiver) .

It is to be understood that the number of apparatuses and their connections shown in FIG. 1A are only for the purpose of illustration without suggesting any limitation. The communication environment 100 may include any suitable number of apparatuses configured to implementing example embodiments of the present disclosure.

Communications in the communication environment 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) , the fifth generation (5G) , the sixth generation (6G) , and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

In some example embodiments, an NTN device switching such as a satellite switching may take place in some situations. FIG. 1B illustrates another example communication environment 150 in which example embodiments of the present disclosure can be implemented. In the communication environment 150, the NTN device switching may happen.

In the following description, it may be assumed that the first apparatus 110 is stationary or moving, and it is currently being served by the NTN device 130. For example, the NTN device 130 may be a serving satellite or referred to as a source satellite. As used herein, the serving NTN device 130 may also be referred to as a source NTN device 130.

As the source NTN device 130 moves away from the first apparatus 110, for example in a moving direction 155, and another NTN device 160 gets closer to the first apparatus, then at a time point the NTN device switching will occur. As used herein, the NTN device 160 may be referred to as a “target NTN device 160” which is to provide a service to the first apparatus 110 after the NTN device switching. As used herein, the term “NTN device switching” may also be referred to as a “switching” .

The network (for example, the second apparatus 120) may indicate the first apparatus 110 when the switching will occur. The second apparatus 120 indicates the first apparatus 110 when and how to perform DL and UL re-synchronization to the new cell after the switching. The first apparatus 110 may adjust its timing and Doppler offset parameters for operation towards the new cell. The second apparatus 120 may alternatively accept an interruption gap for the first apparatus 110 to detect the new timing and adapt to it. Since the PCI, the second apparatus 120, security keys and SSB frequency remain the same, the switching may be mostly transparent to the first apparatus 110. Since the PCI, gNB, security keys and SSB frequency remain the same, the satellite switch may be mostly transparent to the first apparatus 110. Once the target NTN device 160 takes over, the first apparatus 110 may perform DL/UL synchronization operations to adjust time and frequency.

In some example embodiments, for a quasi-earth fixed cell (EFC) scenario, a geographic area 170 is associated with a physical cell ID (PCI) and the second apparatus 120. For the unchanged PCI scenario, the second apparatus 120 may provide services to a same coverage (for example, the geographic area 170) with connecting to different NTN devices (for example, the source NTN device 130 and the target NTN device 160) and the PCI may be kept unchanged after the satellite switching. In this case, an NTN cell is deployed as an EFC since the coverage area of the cell is not change.

When the NTN device switching occurs, the serving NTN device is changed from the source NTN device 130 to the target NTN device 160. The service link 132 between the first apparatus 110 and the source NTN device 130 may change to a different service link 162 between the first apparatus 110 and the target NTN device 160. Likewise, the feeder link 134 between the second apparatus 110 and the source NTN device 130 may change to a different feeder link 164 between the second apparatus 120 and the target NTN device 160.

As illustrated in FIG. 1B, if the first apparatus is served by the source NTN device 130, the TA of the first apparatus 110 may be equal to the round trip time (RTT) between the first apparatus 110 and the second apparatus 120 which includes a propagation delay SL_1 corresponding to the service link 132 and a propagation delay FL_1 corresponding to the feeder link 134 (that is, SL_1 + FL_1) . After the first apparatus 110 switches to the target NTN device 160, a new TA of the first apparatus 110 may be equal to the round trip time (RTT) between the first apparatus 110 and the second apparatus 120 which includes a propagation delay SL_2 corresponding to the service link 162 and a propagation delay FL_2 corresponding to the feeder link 164 (that is, SL_2 +FL_2) .

If the first apparatus 110 is located in the near edge of the coverage of the source NTN device 130, after the switching, a TA jump issue will happen since the (SL_2+FL_2) is larger than the (SL_1+FL_1) . The value of the TA jump (also referred to as a TA jump value) may depend on the cell coverage radius, the serving satellite elevation angle as well as the location of the first apparatus 110. For example, the TA jump value may be at least larger than the differential delay between UEs served by a satellite. By way of example, the TA jump value may be 10ms in geosynchronous equatorial orbit (GEO) . It is to be understood that the TA jump value may be any suitable time value.

In some example embodiments, the second apparatus 120 may need to know the new TA of the target NTN device 160 to obtain the TA jump value. According to some example embodiments of the present disclosure, the first apparatus 110 determines a predicted TA associated with the target NTN device 160 before switching a connection from the source NTN device 130 serving the first apparatus 110 to the target NTN device 160. The target NTN device 160 is to provide a service to the first apparatus 110 after the switching. The first apparatus 110 transmits, to the second apparatus 120, information about the predicted timing advance before the switching.

In this way, the second apparatus 120 can be informed of the new predicted TA. With the new predicted TA, the second apparatus 120 can continue the scheduling in the serving cell after the switching.

FIG. 2 illustrates a signaling diagram 200 for TA reporting according to some example embodiments of the present disclosure. The signaling diagram 200 involves the first apparatus 110 and the second apparatus 120 in FIG. 1A and FIG. 1B. For purpose of illustration, the signaling diagram 200 will be described with respect to FIG. 1A and FIG. 1B.

Although a single first apparatus 110 and a single second apparatus 120 are illustrated in FIG. 2, it would be appreciated that there may be a plurality of apparatuses performing similar operations as described with respect to the first apparatus 110 or the second apparatus 120 below.

In the example of FIG. 2, the second apparatus 120 may be connected to at least one of: the source NTN device 130 before switching, or the target NTN device 160. Alternatively, in some example embodiments, the second apparatus 120 may be located in at least one of: the source NTN device 130 before switching, or the target NTN device 160. The source NTN device 130 and/or the target NTN device 160 may be a satellite, or a high-altitude platform station.

It is noted that example embodiments of the present disclosure can be applied to any proper scenarios, for example, the scenario of satellite switch without RACH in unchanged PCI scenario, or the scenario of RACH-less handover in NTN scenario if there is a satellite switch without RACH. Only for purpose of illustrations, example embodiments of the present disclosure are described with reference to the scenario of satellite switch without RACH.

In operation, the first apparatus 110 determines (230) a predicted TA associated with a target NTN device such as the target NTN device 160 before switching a connection from a source NTN device such as the source NTN device 130 to the target NTN device 160. The source NTN device serves the first apparatus 110. The target NTN device is to provide a service to the first apparatus 110 after the switching.

The first apparatus 110 transmits (250) information about the predicted timing advance to the second apparatus 120 before the switching. The second apparatus 120 receives (255) the information. For example, the first apparatus 110 reports the predicted TA for serving cell with a target satellite to the second apparatus 120 before the satellite switch happens.

In some example embodiments, the first apparatus 110 may transmit, to the second apparatus 120 at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information. For example, if a resource is available for transmission at the first time point, the first apparatus 110 may transmit (250) the information at the first time point. If no resource is available at the first time point for the transmission of the information, the first apparatus 110 may transmit a request for the transmission at the first time point. That is, the first apparatus 110 may trigger the predicted TA reporting for the target NTN device 160 before the switching. By way of example, the request for transmission of the information may be a scheduling request or random access request.

In some example embodiments, the time window may be predefined or configured. In an example, the second apparatus 120 may transmit (240) a configuration of the time window to the first apparatus 110. The first apparatus 110 may receive (245) the configuration of the time window. The second apparatus 120 may assume that the TA information transmission may be completed within the time window.

In some example embodiments, the second apparatus 120 may determine the time window based on at least one of: a RTT between the first apparatus 110 and the second apparatus 120, the number of retransmissions, or a scheduling request (SR) periodicity. It is to be understood that these example parameters for determining the time window are only for the purpose of illustration, without suggesting any limitation. The second apparatus 120 may determine the time window based on any other suitable parameter.

FIG. 3 illustrates an example diagram 300 showing a time point for the information transmission according to some example embodiments of the present disclosure. As shown, a time window 310 is configured by the second apparatus 120. The time window 310 is prior to the switching time point 330. The information about the predicted TA or the request of the transmission of the information may be transmitted at a first time point 340 before a start time point 335 of the time window 310. It is to be understood that in some example embodiments, the first time point 340 may be at the start time point 335 of the time window 310. In this way, the first apparatus 110 may trigger the predicted TA reporting for the target NTN device 160 before the point of (satellite switch time –time window) . There are additional time points shown in FIG. 3, which will be used for transmission of further information.

Referring back to FIG. 2, in some example embodiments, the predicted TA information may be transmitted (250) based on one or more conditions. For example, the first apparatus 110 may determine (235) whether a difference between the predicted TA associated with the target NTN device 160 and a reference TA associated with the source NTN device 130 is greater than or equal to a threshold. If the first apparatus 110 determines (235) that the difference is greater than or equal to the threshold, the first apparatus 110 may transmit (250) the information to the second apparatus 120.

In this way, the first apparatus 110 reports the predicted TA for serving cell with the target NTN device 160 only if the variation (between the reported TA for serving cell with the source NTN device 130 and the predicted TA for serving cell with the target NTN device 160) is larger than or equal to the threshold. The signaling overhead can be thus reduced.

It is to be understood that other condition than the threshold may be used for the transmission of the predicted TA information. Scope of the present disclosure is not limited in this regard.

As described, the first apparatus 110 determines (230) the predicted TA. In some example embodiments, the second apparatus 120 may transmit (220) ephemeris information of the target NTN device 160 and a set of TA parameters to the first apparatus 110. The first apparatus 110 may receive (225) the ephemeris information of the target NTN device 160 and the set of TA parameters. By way of example, the set of TA parameters may be common TA parameters. The first apparatus 110 may determine (230) the predicted TA based on the ephemeris information and the set of TA parameters.

In this way, the second apparatus 120 provides the ephemeris information of the target NTN device 160 such as a target satellite’s ephemeris information and common TA parameters to the first apparatus 110 before satellite switch happens. It thus enables the first apparatus 110 to predict the TA for serving cell with target satellite.

In some example embodiments, the second apparatus 120 may transmit (220) the ephemeris information and the set of TA parameters to the first apparatus 110 at a second time point before the first time point for the predicted TA request or reporting. An offset of the second time point with respect to the first time point may be predefined or configured. In another example, the offset of the second time point with respect to the time window for the predicted TA transmission may be predefined or configured. For example, the second apparatus 120 may transmit (210) a configuration of the offset to the first apparatus 110. The first apparatus 110 may receive (215) the configuration of the offset. The offset may be with respect to the first time point or the time window associated with the first time point.

As illustrated in FIG. 3, an offset 320 is configured by the second apparatus 120. The offset 320 is prior to the time point 335 of the time window 310. The ephemeris information and the set of TA parameters may be transmitted (210) at a second time point 350 before a time point 345 with the offset 320 with respect to the time window 310. It is to be understood that in some example embodiments, the second time point 350 may be at the time point 345.

In this way, the second apparatus 120 may configure an offset to the first apparatus 110, in which the second apparatus 120 may provide the information of the target NTN device 160 and TA parameters upon the time-point of (satellite switch time –time window –offset) . By way of example, the ephemeris information and the set of TA parameters may be provided to the first apparatus 110 via system information block (SIB) or any other suitable signaling. For example, t-Service in SIB19 may be interpreted by the first apparatus 110 in connected mode to know that a satellite change or feeder link change happens. The first apparatus 110 may start to receive or decode the ephemeris information and the set of TA parameters from the second time point.

In some example embodiments, the second apparatus 120 may determine the value of offset by considering the time required for TA estimation in the first apparatus 110 based on the ephemeris and common TA, as well as the configured system information (SI) modification period.

In some example embodiments, the predicted TA for serving cell with target NTN device 160 may be reported in different formats. In an example, the information about the predicted TA may include the predicted TA associated with the target NTN device 160 such as a predicted TA value. The first apparatus 110 may report the predicted TA via RRC message such as UE assistance information, in which an absolute predicted TA value may be included. The first apparatus 110 may alternatively report the predicted TA via a new medium access control control element (MAC CE) such as a new UL MAC CE. For example, a plurality of most significant bit (MSB) or a plurality of least significant bit (LSB) bits in at least one octet (OCT) in the MAC CE may be used for the predicted TA value.

FIG. 4A illustrates an example MAC CE format 410 for TA reporting. The MAC CE for predicted TA reporting may be identified by MAC subheader with logical channel identification (LCID) . For example, six LSB bits of a first OCT 412 and eight bits in a second OCT 414 next to the first OCT 412 in the MAC CE may be used for the predicted TA value. Two MSB bits in the first OCT 412 may be reserved. The reserved bits may be set to 0. It is to be understood that this example MAC CE format 410 is only for purpose of illustration, without suggesting any limitation. Any suitable MAC CE may be applied. Scope of the present disclosure is not limited in this regard.

Alternatively, or in addition, in some example embodiments, the information about the predicted TA may include a reference TA associated with the source NTN device 130 and a difference between the predicted TA and the reference TA. As used herein, the difference between the predicted TA and the reference TA may also be referred to as a “TA difference” or “TA jump” or “TA jump value” . For example, the difference between the predicted TA and the reference TA may be carried in at least one reserved bit in a MAC CE. The at least one reserved bit may indicate a ratio of the difference to a predetermined TA difference.

A plurality of bits in the MAC CE may be used for the reference TA. For example, in the scenario of frequency range 1 (FR1) , the TA field indicates the least integer number of slots, using subcarrier spacing of 15 kHz, greater than or equal to the TA value. The length of the field may be 14 bits. That is, 14 bits may be used for the reference TA. It is to be understood that in other scenario, more or less bits may be used for the reference TA.

FIG. 4B illustrates an example MAC CE format 430 for the predicted TA and the reference TA. As illustrated, two MSB bits in a first OCT 432 in the MAC CE may indicate the difference between the predicted TA and the reference TA. Six LSB bits in the OCT 432 and eight bits in a second OCT 434 next to the first OCT 432 in the MAC CE may indicate the reference TA value. It is to be understood that this example MAC CE format 430 is only for purpose of illustration, without suggesting any limitation. Any suitable MAC CE may be applied. Scope of the present disclosure is not limited in this regard.

In some example embodiments, the second apparatus 120 may indicate the predetermined TA difference such as a maximum TA jump to the first apparatus b110 via RRC or SIB. Alternatively, the predetermined TA difference or the maximum TA jump may be pre-defined, such as 20ms or any suitable value.

The first apparatus 110 may indicate the TA jump via index in spare bits in MAC CE, to indicate the percentage of maximum TA jump. In the example of FIG. 4B, the two reserved bits may indicate the TA jump value. The index in the two reserved bits may be 00/01/10/11. For example, “00” means the TA jump value is less than a quarter of the maximum TA jump, “01” means the TA jump value is in the range from a quarter to a half of the maximum TA jump, “10” means the TA jump range is in the range from a half to three quarters of the maximum TA jump, and “11” means the TA jump value is in the range from three quarters to the full of the maximum TA jump. Alternatively, the index “00” may be used to indicate no TA jump while the index “01” / “10” / “11” may be used to indicate other TA jump ranges. It is to be understood that these example indexes and TA jump ranges are only for purpose of illustration, without suggesting any limitation.

The predicted TA for serving cell with target NTN device 160 may be equal to a sum of the TA value reported for serving cell with source NTN device 130 and the TA jump. The TA value for source NTN device 130 may be indicated via legacy 14 bits in UL MAC CE while the TA jump may be indicated via two spare bits in the same MAC CE as shown in FIG. 4B.

In this way, both the TA for serving cell with source NTN device 130 and TA for serving cell with target NTN device 160 are reported to the second apparatus 120 via a single UL MA CE. The signaling thus can be more efficient. The signaling design is efficient, by re-purposing the R-bits in legacy UL MAC CE for TA reporting for serving cell with source satellite.

Back to FIG 2, in some example embodiments, the second apparatus 120 determines (260) , based on the information about the predicted TA, a configuration of a transmission time offset for a transmission of the first apparatus 110. The second apparatus 120 may transmit (265) the configuration of the transmission time offset to the first apparatus 110. The first apparatus 110 may receive (270) the configuration. As used herein, the transmission time offset may also be referred to as a “Koffset specific to the first apparatus 110” or an “UE-specific Koffset” .

In some example embodiments, the second apparatus 120 may indicate the transmission time offset for scheduling after switching via DL MAC CE as defined in legacy. Alternatively, or in addition, in some example embodiments, the second apparatus 120 may indicate the transmission time offset for scheduling after switching via physical downlink control channel (PDCCH) or RRC. This is beneficial to adjust the UE-specific Koffset together with the UL grant after the switching.

In an example, based on the reported TA for target NTN device 160, the second apparatus 120 may schedule the first apparatus 110 based the new TA upon the switching such as the satellite switch. Alternatively, or in addition, the second apparatus 120 may schedule the first apparatus 110 based on the new TA after an interruption length after the switching (such as, satellite switch + interruption length) . The interruption length may be predefined or configured. In one example, the interruption length may be the time for the first apparatus 110 to re-synchronization to target NTN device 160.

The first apparatus 110 may switch (275) a connection from the source target NTN device 130 to the target NTN device 160. After the switching (275) , the first apparatus 110 may perform (280) a transmission based on the received (270) configuration of the transmission time offset.

In some example embodiments, the PUSCH transmission (s) may be delayed with Koffset as compared to the transmission (s) . The Koffset may be the result of cell-specific Koffset (indicated by SIB) minus a Koffset specific to the first apparatus 110 such as a UE-specific Koffset (indicated by MAC CE) . The Koffset specific to the first apparatus 110 such as the UE-specific Koffset may be the transmission time offset configured by the second apparatus 120.

The cell-specific Koffset may be intended as a rough value that applies to all first apparatuses in the cell which may be larger than the maximum TA among all the first apparatuses. The UE-specific Koffset is a delta that is applied on the top. With the reported TA from the first apparatus 110, it is possible to assist network to configure the first apparatus 110 with a proper UE-specific Koffset, which can reduce the UL latency and improve scheduling efficiency. For example, the final Koffset is larger but close to an RTT between the first apparatus 110 and the second apparatus 120 instead of using a largest UE-eNB RTT among all UEs. In other words, if no TA report available, it is not possible for NW to configure UE-specific Koffset, and therefore the UE has to apply the final Koffset as the cell-specific Koffset.

Therefore, by configuring the transmission time offset (i.e., the Koffset specific to the first apparatus 110) , the UL latency can be reduced, and the scheduling efficiency can be improved.

To guarantee the first apparatus 110 to have sufficient time for TA adjustment and UL processing delay, the timing of the scheduled transmission of the first apparatus 110 needs to be larger than an actual transmission time which the first apparatus 110 applied.

FIG. 5 illustrates an example diagram 500 showing scheduling time relationship according to some example embodiments of the present disclosure. In the description of FIG. 5, it is assumed that the first apparatus 110 is implemented as a terminal device, and the second apparatus 120 is implemented as a network device. As illustrated, the timing of the scheduled UL transmission of the first apparatus 110 (i.e., n+4+Koffset) needs to be larger than an actual transmission time which the first apparatus 110 applied (i.e., n+TA+UL processing delay) . In other words, (Koffset + 4) needs to be larger than (TA+UL processing delay) . A value of the Koffset may be configured by the second apparatus 120 based on a predefined or configured condition. An example condition may be that Koffset > TA + UL processing delay -4. With such condition, it can make sure that the timing of the scheduled transmission of the first apparatus 110 is larger than an actual transmission time which the first apparatus 110 applied.

With the predicted TA information, the second apparatus 120 can configure the transmission time offset (such as the UE-specific Koffset) based on the predicted TA and the condition that Koffset > TA + UL processing delay -4. It is to be understood that such example condition is only for the purpose of illustration, without suggesting any limitation. Any suitable condition or calculation may be applied for determining the transmission time offset based on the predicted TA. Scope of the present disclosure is not limited in this regard.

The present solution enables the UE to report the predicted TA for serving cell with target satellite, in the scenario of satellite switch without RACH. This is mandatory to avoid the granted UL transmission failure since the Koffset may be configured/adapted based on UE-specific RTT. By using the predicted TA reporting for satellite switch without RACH in unchanged PCI scenario, it can avoid the scheduled UL transmission failure after the switch.

FIG. 6 shows a flowchart of an example method 600 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the first apparatus 110 in FIG. 1A and FIG. 1B.

At block 610, the first apparatus 110 determines a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device. The source non-terrestrial network device serves the first apparatus, and the target non- terrestrial network device provides a service to the first apparatus after the switching.

At block 620, the first apparatus 110 transmits, to a second apparatus, information about the predicted timing advance before the switching.

In some example embodiments, the method 600 further comprises: switching the connection from the source non-terrestrial network device to the target non-terrestrial network device without a random access procedure.

In some example embodiments, the method 600 further comprises: transmitting, to the second apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.

In some example embodiments, the method 600 further comprises: receiving, from the second apparatus, a configuration of the time window.

In some example embodiments, the method 600 further comprises: determining that a difference between the predicted timing advance associated with the target non-terrestrial network device and a reference timing advance associated with the source non-terrestrial network device is greater than or equal to a threshold; and based on the determining, transmitting the information to the second apparatus.

In some example embodiments, the information comprises at least one of: the predicted timing advance associated with the target non-terrestrial network device, or a reference timing advance associated with the source non-terrestrial network device and a difference between the predicted timing advance and the reference timing advance.

In some example embodiments, the predicted timing advance is carried in a medium access control control element, or the difference between the predicted timing advance and the reference timing advance is carried in at least one reserved bit in a medium access control control element, and the at least one reserved bit indicates a ratio of the difference to a predetermined timing advance difference.

In some example embodiments, the method 600 further comprises: receiving, from the second apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters; and determining the predicted timing advance based on the ephemeris information and the set of timing advance parameters.

In some example embodiments, the method 600 further comprises: receiving, from the second apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point, wherein at least one of the information or a request for transmission of the information is transmitted to the second apparatus at the first time point.

In some example embodiments, the method 600 further comprises: receiving, from the second apparatus, a configuration of an offset of the second time point with respect to the first time point.

FIG. 7 shows a flowchart of an example method 700 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the second apparatus 120 in FIG. 1A and FIG. 1B.

At block 710, the second apparatus 120 receives, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device. The source non-terrestrial network device serves the first apparatus, and the target non-terrestrial network device provides a service to the first apparatus after the switching.

At block 720, the second apparatus 120 determines, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.

In some example embodiments, the method 700 further comprises: receiving, from the first apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.

In some example embodiments, the method 700 further comprises: determining the time window based on at least one of: a round trip time between the first apparatus and the second apparatus, the number of retransmissions, or a scheduling request periodicity; and transmitting, to the first apparatus, a configuration of the time window.

In some example embodiments, the method 700 further comprises: transmitting, to the first apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters.

In some example embodiments, the method 700 further comprises: transmitting, to the first apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point, wherein at least one of the information or a request for transmission of the information is received from the first apparatus at the first time point.

In some example embodiments, the method 700 further comprises: transmitting, to the first apparatus, a configuration of an offset of the second time point with respect to the first time point.

In some example embodiments, the method 700 further comprises: transmitting, to the first apparatus, the configuration of the transmission time offset.

In some example embodiments, the second apparatus is connected to at least one of: the source non-terrestrial network device before switching, or the target non-terrestrial network device, or the second apparatus is located in at least one of: the source non-terrestrial network device before switching, or the target non-terrestrial network device.

In some example embodiments, a non-terrestrial network device comprises at least one of: a satellite, or a high-altitude platform station.

In some example embodiments, a first apparatus capable of performing any of the method 600 (for example, the first apparatus 110 in FIG. 1A and FIG. 1B) may comprise means for performing the respective operations of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1A and FIG. 1B.

In some example embodiments, the first apparatus comprises means for determining a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and means for transmitting, to a second apparatus, information about the predicted timing advance before the switching.

In some example embodiments, the first apparatus further comprises: means for switching the connection from the source non-terrestrial network device to the target non-terrestrial network device without a random access procedure.

In some example embodiments, the first apparatus further comprises: means for transmitting, to the second apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.

In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, a configuration of the time window.

In some example embodiments, the first apparatus further comprises: means for determining that a difference between the predicted timing advance associated with the target non-terrestrial network device and a reference timing advance associated with the source non-terrestrial network device is greater than or equal to a threshold; and means for based on the determining, transmitting the information to the second apparatus.

In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters; and means for determining the predicted timing advance based on the ephemeris information and the set of timing advance parameters.

In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point, wherein at least one of the information or a request for transmission of the information is transmitted to the second apparatus at the first time point.

In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, a configuration of an offset of the second time point with respect to the first time point.

In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of the method 600 or the first apparatus 110. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the first apparatus.

In some example embodiments, a second apparatus capable of performing any of the method 700 (for example, the second apparatus 120 in FIG. 1A and FIG. 1B) may comprise means for performing the respective operations of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1A and FIG. 1B.

In some example embodiments, the second apparatus comprises means for receiving, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and means for determining, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.

In some example embodiments, the second apparatus further comprises: means for receiving, from the first apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.

In some example embodiments, the second apparatus further comprises: means for determining the time window based on at least one of: a round trip time between the first apparatus and the second apparatus, the number of retransmissions, or a scheduling request periodicity; and means for transmitting, to the first apparatus, a configuration of the time window.

In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters.

In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point, wherein at least one of the information or a request for transmission of the information is received from the first apparatus at the first time point.

In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, a configuration of an offset of the second time point with respect to the first time point.

In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, the configuration of the transmission time offset.

In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of the method 700 or the second apparatus 120. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the second apparatus.

FIG. 8 is a simplified block diagram of a device 800 that is suitable for implementing example embodiments of the present disclosure. The device 800 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1A and FIG. 1B. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processor 810, and one or more communication modules 840 coupled to the processor 810.

The communication module 840 is for bidirectional communications. The communication module 840 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 840 may include at least one antenna.

The processor 810 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 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.

The memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 824, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , an optical disk, a laser disk, and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 822 and other volatile memories that will not last in the power-down duration.

A computer program 830 includes computer executable instructions that are executed by the associated processor 810. The instructions of the program 830 may include instructions for performing operations/acts of some example embodiments of the present disclosure. The program 830 may be stored in the memory, e.g., the ROM 824. The processor 810 may perform any suitable actions and processing by loading the program 830 into the RAM 822.

The example embodiments of the present disclosure may be implemented by means of the program 830 so that the device 800 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 7. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 830 may be tangibly contained in a computer readable medium which may be included in the device 800 (such as in the memory 820) or other storage devices that are accessible by the device 800. The device 800 may load the program 830 from the computer readable medium to the RAM 822 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

FIG. 9 shows an example of the computer readable medium 900 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 900 has the program 830 stored thereon.

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, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method 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.

Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. 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. The program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, 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.

In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer 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 computer 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, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although 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. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages 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 first apparatus comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus to:

determine a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

transmit, to a second apparatus, information about the predicted timing advance before the switching.
The first apparatus of claim 1, wherein the first apparatus is caused to:

switch the connection from the source non-terrestrial network device to the target non-terrestrial network device without a random access procedure.
The first apparatus of claim 1 or claim 2, wherein the first apparatus is caused to:

transmit, to the second apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.
The first apparatus of claim 3, wherein the first apparatus is further caused to:

receive, from the second apparatus, a configuration of the time window.
The first apparatus of any of claims 1-4, wherein the first apparatus is caused to:

determine that a difference between the predicted timing advance associated with the target non-terrestrial network device and a reference timing advance associated with the source non-terrestrial network device is greater than or equal to a threshold; and

based on the determining, transmit the information to the second apparatus.
The first apparatus of any of claims 1-5, wherein the information comprises at least one of:

the predicted timing advance associated with the target non-terrestrial network device, or

a reference timing advance associated with the source non-terrestrial network device and a difference between the predicted timing advance and the reference timing advance.
The first apparatus of claim 6, wherein

the predicted timing advance is carried in a medium access control control element, or

the difference between the predicted timing advance and the reference timing advance is carried in at least one reserved bit in a medium access control control element, and the at least one reserved bit indicates a ratio of the difference to a predetermined timing advance difference.
The first apparatus of any of claims 1-7, wherein the first apparatus is caused to:

receive, from the second apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters; and

determine the predicted timing advance based on the ephemeris information and the set of timing advance parameters.
The first apparatus of claim 8, wherein the first apparatus is further caused to:

receive, from the second apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point,

wherein at least one of the information or a request for transmission of the information is transmitted to the second apparatus at the first time point.
The first apparatus of claim 9, wherein the first apparatus is further caused to:

receive, from the second apparatus, a configuration of an offset of the second time point with respect to the first time point.
A second apparatus comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus to:

receive, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

determine, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.
The second apparatus of claim 11, wherein the second apparatus is caused to:

receive, from the first apparatus at a first time point before a time window prior to the switching, at least one of: the information, or a request for transmission of the information.
The second apparatus of claim 12, wherein the second apparatus is further caused to:

determine the time window based on at least one of: a round trip time between the first apparatus and the second apparatus, the number of retransmissions, or a scheduling request periodicity; and

transmit, to the first apparatus, a configuration of the time window.
The second apparatus of any of claims 11-13, wherein the information comprises at least one of:

the predicted timing advance associated with the target non-terrestrial network device, or

a reference timing advance associated with the source non-terrestrial network device and a difference between the predicted timing advance and the reference timing advance.
The second apparatus of claim 14, wherein

the predicted timing advance is carried in a medium access control control element, or

the difference between the predicted timing advance and the reference timing advance is carried in at least one reserved bit in a medium access control control element, and the at least one reserved bit indicates a ratio of the difference to a predetermined timing advance difference.
The second apparatus of any of claims 11-15, wherein the second apparatus is caused to:

transmit, to the first apparatus, ephemeris information of the target non-terrestrial network device and a set of timing advance parameters.
The second apparatus of claim 16, wherein the second apparatus is further caused to:

transmit, to the first apparatus, the ephemeris information and the set of timing advance parameters at a second time point before a first time point,

wherein at least one of the information or a request for transmission of the information is received from the first apparatus at the first time point.
The second apparatus of claim 17, wherein the second apparatus is further caused to:

transmit, to the first apparatus, a configuration of an offset of the second time point with respect to the first time point.
The second apparatus of any of claims 11-18, wherein the second apparatus is caused to:

transmit, to the first apparatus, the configuration of the transmission time offset.
The second apparatus of any of claims 11-19, wherein

the second apparatus is connected to at least one of: the source non-terrestrial network device before switching, or the target non-terrestrial network device, or

the second apparatus is located in at least one of: the source non-terrestrial network device before switching, or the target non-terrestrial network device.
The second apparatus of any of claims 11-20, wherein a non-terrestrial network device comprises at least one of:

a satellite, or

a high-altitude platform station.
A method comprising:

determining, at a first apparatus, a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

transmitting, to a second apparatus, information about the predicted timing advance before the switching.
A method comprising:

receiving, at a second apparatus from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

determining, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.
A first apparatus comprising:

means for determining a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

means for transmitting, to a second apparatus, information about the predicted timing advance before the switching.
A second apparatus comprising:

means for receiving, from a first apparatus, information about a predicted timing advance associated with a target non-terrestrial network device before switching a connection from a source non-terrestrial network device to the target non-terrestrial network device, the source non-terrestrial network device serving the first apparatus and the target non-terrestrial network device providing a service to the first apparatus after the switching; and

means for determining, based on the information, a configuration of a transmission time offset for a transmission of the first apparatus.
A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of claim 22 or the method of claim 23.