Enhancement on timing advance determination

Abstract

A Timing Advance (TA) determination method comprises receiving, by a first apparatus 110 from a second apparatus 120, information of a grid of fixed locations 402 ; determining 404 a target grid point

Description

FIELD

[0001] 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 enhancement on Timing Advance (TA) determination. BACKGROUND

[0002] User Equipment (UE)’s pre-compensation of time in uplink (UL) transmission is called TA, which is the round-trip time of signal propagation to a “reference point” of infrastructure (e.g., a network device, such as a gNodeB (gNB)) where downlink (DL) and UL subframes are aligned. The DL and UL subframes are aligned at gNB scheduler (although a fixed offset is possible due to network implementation). The scheduler needs to take into account the large TA for the allocated UL resources. SUMMARY

[0003] 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 at least to: receive, from a second apparatus, information of a grid of fixed locations; determine a target grid point in the grid associated with a reference location of the first apparatus; generate, at least based on the target grid point, a reference location report including an indication associated with the target grid point; and transmit the reference location report to the second apparatus.

[0004] 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 at least to: transmit, to a first apparatus, information of a grid of fixed locations; receive, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; and determine a TA between the first apparatus and the second apparatus at least based on the reference location report.

[0005] In a third aspect of the present disclosure, there is provided a method. The method comprises: receiving, by a first apparatus from a second apparatus, information of a grid of fixed locations; determining a target grid point in the grid associated with a reference location of the first apparatus; generating, at least based on the target grid point, a reference location report including an indication associated with the target grid point; and transmitting the reference location report to the second apparatus.

[0006] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: transmitting, from a second apparatus to a first apparatus, information of a grid of fixed locations; receiving, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; and determining a TA between the first apparatus and the second apparatus at least based on the reference location report.

[0007] In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, information of a grid of fixed locations; means for determining a target grid point in the grid associated with a reference location of the first apparatus; means for generating, at least based on the target grid point, a reference location report including an indication associated with the target grid point; and means for transmitting the reference location report to the second apparatus.

[0008] In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for transmitting, to a first apparatus, information of a grid of fixed locations; means for receiving, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; and means for determining a TA between the first apparatus and the second apparatus at least based on the reference location report.

[0009] 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.

[0010] In an eighth 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 fourth aspect.

[0011] 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

[0012] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0013] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0014] FIG. 2 illustrates an example of TA for UL transmission;

[0015] FIG. 3 illustrates a diagram of service link TA (RTT between the satellite and UE) as function of time;

[0016] FIG. 4 illustrates a signaling chart of communication according to some example embodiments of the present disclosure;

[0017] FIG. 5 illustrates an example of grid according to some example embodiments of the present disclosure;

[0018] FIG. 6 illustrates a signaling chart of communication according to some example embodiments of the present disclosure;

[0019] FIG. 7 illustrates a flowchart of a method implemented at a first apparatus in accordance with some example embodiments of the present disclosure;

[0020] FIG. 8 illustrates a flowchart of a method implemented at a second apparatus in accordance with some example embodiments of the present disclosure;

[0021] FIG. 9 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0022] FIG. 10 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0023] Throughout the drawings, the same or similar reference numerals represent the same or similar element. DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] As used herein, “at least one of the following: ” and “at least one of ” 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.

[0029] As used herein, unless stated explicitly, performing a step “in response to A” 5 does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0030] 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 10 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. 15

[0031] 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.

[0032] 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.

[0033] 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, 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.

[0034] 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.

[0035] 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 (loT) 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.

[0036] 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.

[0037] FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 may comprise a first apparatuses 110-1 and 110-2 which may be referred to as a first apparatus 110. The first apparatus 110 may be, for example, a terminal device. In some example embodiments, the terminal device may also be discussed as a UE.

[0038] The communication network 100 may further comprise a second apparatus 120, which may be, for example, a network device on the ground. In some example embodiments, the network device may be discussed as a ground station, BS, a gNB, or an eNB.

[0039] In some scenarios, such as an NTN scenario, the first apparatus 110 may communicate with the second apparatus via an NTN device 101 (such as a satellite) hosting an RAN device (e.g., the second apparatus 120). The first apparatus 110 may communicate with the NTN device 101 within a cell coverage 102.

[0040] In the following, for the 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.

[0041] In some example embodiments, if the first apparatus 110 is a terminal device and 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) apparatus (or a transmitter) and the first apparatus 110 is a receiving (RX) apparatus (or a receiver). In UL, the first apparatus 110 is a TX apparatus (or a transmitter) and the second apparatus 120 is a RX apparatus (or a receiver).

[0042] It is to be understood that the number of network devices and terminal devices shown in FIG. 1 is given for the purpose of illustration without suggesting any limitations. The communication environment 100 may include any suitable number of network devices and terminal devices.

[0043] 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), 5.5G, 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.

[0044] Since 3GPP Release 17, LTE and NR may support the feature of NTN, using satellites and High Altitude Platform Station (HAPS) to provide mobile data services. In those deployment scenarios, data delivery often experiences a much longer delay compared to legacy cellular networks. In some cases, e.g., non-geosynchronous Low Earth Orbiting (LEO), Medium Earth Orbiting (MEO) satellites, the satellite motion also creates a significant frequency shift and a rapidly changing delay. An NTN cell can have a large footprint, spanning hundreds of kilometers. Within the same cell, UEs in different locations can experience widely diverse delays and frequency shifts.

[0045] To maintain multi-user orthogonality in UL Orthogonal Frequency Division Multiple Access (OFDMA) waveform, signals from different UEs have to arrive at the satellite aligned in time and frequency. This requires timing and frequency compensation from the UE during the UL transmission to offset the delay and frequency shift caused by satellite motion. To calculate the timing and frequency compensation, the UE needs the ephemeris data (satellite movement information) provided in System Information Block (SIB) and the UE’s own position from its Global Navigation Satellite System (GNSS) receiver.

[0046] As described above, UE’s pre-compensation of time in UL transmission is called TA, which is the round-trip time of signal propagation to a “reference point” of infrastructure (e.g., gNB) where DL and UL subframes are aligned. TA is expressed as: ^A = (^TA + + ^TA^F" + 0) where Tc is the basic time unit. The first two terms are legacy parameters, and the last two terms are specific to NTN. represents a common TA component for all the UEs (i.e., the first apparatuses 110-1 and 110-2) in the cell. This can be the Round-Trip Time (RTT) between the satellite (i.e., the NTN device 101) and the ground station (i.e., the second apparatus 120) where gNB is located, denoted as TQ in FIG. 1. A4^adj represents the RTT between the satellite and the UEs, denoted as T, and T2 for UE1 (i.e., the first apparatus 110-1) and UE2 (i.e., the first apparatus 110-2) respectively.

[0047] Typically the DL and UL subframes are aligned at gNB scheduler (although a fixed offset is possible due to network implementation). The scheduler needs to take into account the large TA for the allocated UL resources. When an UL transmission is scheduled by a Physical Downlink Control Channel (PDCCH) in DL slot n, the corresponding UL resources must be scheduled later than the UE’s TA after slot n. This is illustrated in FIG. 2 assuming TA is 6 slot long and the UL transmission starts at 8 slots after PDCCH. If the duration between the end of PDCCH and the start of Physical Uplink Shared Channel (PUSCH) is not larger TA, the UL transmission would not be physically possible.

[0048] In NR, the scheduler uses a cell-wise parameter Koffset when scheduling UL resources in NTN. The start time of UL PUSCH transmission is indicated by a parameter K2 in the time domain resource assignment field of the Downlink Control Information (DCI) (carried by PDCCH). If the slot is received at DL slot n, the UE should start PUSCH transmission at UL slot n + K2 + / ^offset-

[0049] NTN is expected to be integrated as an essential part of 6G to provide ubiquitous connectivity around the globe. A large number of Internet of Things (loT) devices and sensors in remote areas can be accessed by application servers over NTN. Low complexity, low cost wireless devices designed for Low Power Wide Area (LPWA) networks may be an important use case for NTN in 6G. For those devices, power efficiency is essential for a long battery life.

[0050] In terrestrial networks, TA is just a fraction of an Orthogonal Frequency Division Multiple (OFDM) symbol in the order of micro-second. But in NTN, TA can vary in a wide range, from a few milli-seconds to almost half a second, depending on the satellite orbit and elevation angle with the UE. TA may also change rapidly if the satellite is Non-Geosynchronous Orbit (NGSO).

[0051] FIG. 3 shows how the service link TA (i.e., RTT between the satellite and UE) changes over time for a LEO satellite in 600 km orbit, assuming connection starts when the satellite is at 20° elevation angle and ends at 20° elevation angle in the opposite direction. The service link TA, denoted as adj in time unit Tc in equation (1), is completely unknown to the gNB. It has to be calculated by the UE based on the satellite ephemeris in the SIB and the UE’s knowledge of its own location, and the TA must be pre-compensated in UL transmission.

[0052] For Half-Duplex (HD)-Frequency Division Duplex (FDD) UE, which can be RedCap, LTE-M, Narrow Band (NB)-IoT, or 6G LPWA devices, the UE is not expected to receive data in DL, including monitoring PDCCH, while transmitting in UL. It is the responsibility of gNB scheduler to avoid the DL / UL conflict (i.e., simultaneous DL reception and UL transmission) for those HD-FDD devices. This would not be a problem for terrestrial networks as the TA is almost negligible in comparison to the resource time unit of a slot duration. For NTN, however, the TA spans multiple slots, varies over time, and differs among UEs. In that case, the gNB needs knowledge of the UE’s TA to the slot accuracy to perform resource scheduling.

[0053] Sending the TA report frequently (due to the rapid satellite motion in NTN) can significantly drain the limited power resources of LPWA UEs. It is to be discussed how can the gNB in NTN networks always obtain up-to-date TA of LPWA UEs without draining the limited power resources of these low-complexity devices. Then the

[0054] In accordance with some example embodiments of the present disclosure, there is provided a solution for the TA report. In this solution, the first apparatus 110 receives, from a second apparatus, information of a grid of fixed locations. Then the first apparatus 110 determines a target grid point in the grid associated with a reference location of the first apparatus and generates, at least based on the target grid point, a reference location report including an indication associated with the target grid point. Then the reference location report is transmitted to the second apparatus.

[0055] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0056] Reference is now made to FIG. 4, which shows a signaling chart 400 for communication according to some example embodiments of the present disclosure. As shown in FIG. 4, the signaling chart 400 involves a first apparatus 110 and a second apparatus 120. For the purpose of discussion, reference is made to FIG. 1 to describe the signaling chart 400.

[0057] The process described with reference to FIG. 4 may be used for an NTN scenario. It is to be understood that this process may also be used for a non-NTN scenario.

[0058] As shown in FIG. 4, the second apparatus 120 may transmit (402), to the first apparatus 110, information of a grid of fixed locations. For example, the grid may be pre-configured by the second apparatus 120 with equally spaced grid points. The information of grid, for example, may comprise an orientation of the grid, a distance between the two adjacent grid points as well as an origin of the grid. At least a part of parameters in the information of the grid mentioned herein may be fixed in the specification. That is, some parameters may be known by both the first apparatus 110 and the second apparatus 120 without an information exchange.

[0059] In some embodiments, the origin of the grid may be configured by the second apparatus 120 as being a cell-specified origin. That is, the origin of the grid may be specified for a cell within which the first apparatus 110 is located. In this case, the information may be transmitted from the second apparatus 120 to the first apparatus 110 via the SIB.

[0060] In some other embodiments, the origin of the grid may be configured by the second apparatus 120 as being a UE-specified origin. That is, the origin of the grid may be specified for the first apparatus 110. In this case, the information may be transmitted from the second apparatus 120 to the first apparatus 110 via an RRC signaling or small data transmission.

[0061] Based on the information of grid and the location of the first apparatus 110, the first apparatus 110 may select (404) a target grid point from the grid points in the grid for a reference location report. For example, the first apparatus 110 may select the nearest grid point from the grid points in the grid as the target grid point. Alternatively, the first apparatus 110 may randomly select a grid point from the grid points in the grid that meet the required timing advance accuracy as the target grid point.

[0062] FIG. 5 illustrates an example of grid according to some example embodiments of the present disclosure. As shown in FIG. 5, grid points in the grid are spaced with each other with a grid point spacing d. It is to be understood that the grid point spacing d may be configured properly so that the UE’s precise location is not revealed but at the same time allows gNB sufficient TA accuracy for scheduling purposes.

[0063] The grid point {i=l, j=0} is nearest grid point of the apparatus and therefore may be selected as the target grid point.

[0064] Then the first apparatus 110 may transmit (406), to the second apparatus 120 a reference location report indicating the target grid point via an RRC signaling or small data transmission procedure. For example, the reference location report may include an index (or indices) of the target grid point. In this way, since UE only needs to report the index (or indices) of the selected grid point, the data size can be smaller than reporting TA values, thus providing an additional overhead saving.

[0065] Upon receiving the reference location report indicating the target grid point, the second apparatus 120 may calculate (408) the location of the first apparatus 110 based on the indication of the target grid point and the information of the grid. For example, the second apparatus 120 may use the location of the indicated target grid point as the approximate location of the first apparatus 110.

[0066] Then the second apparatus 120 may further calculate (410) the TA based on the derived approximate location of the first apparatus 110. For example, by using this approximate location, the second apparatus 120 may estimate the first apparatus 110’s service link TA (i.e., an RTT between the satellite 101 and the first apparatus 110) by calculating the RTT between the approximate location and current satellite position. In case the second apparatus 120 is located on the ground (e.g., co-located with the ground station), the common TA between the satellite 101 and the second apparatus 120 must be added to the service link TA for the total TA between the first apparatus 110 and the second apparatus 120.

[0067] For example, the common TA can be readily calculated by NTN with the satellite ephemeris. Since TA changes as the satellite moves, the second apparatus 120 may need to calculate the service link TA of the first apparatus 110 when scheduling DL / UL transmissions for the first apparatus 110. The initial reference location report should occur in RRC Connection Establishment procedure when the first apparatus 110 enters Connected state from Idle state.

[0068] After determining the TA between the first apparatus 110 and the second apparatus 120, the second apparatus 120 may schedule the DL / UL transmission by using the TA. Then the DL / UL transmission may be performed (412 and 414) between the first apparatus 110 and the second apparatus 120.

[0069] An updated reference location report may be triggered in a certain condition. When the first apparatus 110 is in RRC connected state, validity of the reference location report can be determined by the change of the location of the first apparatus 110 since the last report. For example, in a case where the location change distance threshold Dth is configured by network for the maximum displacement of the first apparatus 110 without another reference location report, if the first apparatus 110 moves beyond Dth since the last reference location report, a transmission of a new reference location report may be triggered based on its current location. The new report may include a new index (or new indices) of a new target grid point selected by the first apparatus 110. In so doing, data size of the report can be reduced. Alternatively, when the first apparatus 110 is in RRC inactive state, it may determine the validity of the reference location report based on its current location and, if triggered, transmit a new reference location report via a small data transmission procedure.

[0070] Reference is now made to FIG. 6, which shows a signaling chart 600 for communication according to some example embodiments of the present disclosure. As shown in FIG. 6, the signaling chart 600 involves a first apparatus 110 and a second apparatus 120. For the purpose of discussion, reference is made to FIG. 1 to describe the signaling chart 600.

[0071] As shown in FIG. 6, if the first apparatus 110 detects that the location of the first apparatus 110 has changed beyond the location change distance threshold Dth, the first apparatus 110 may re-select (602) a new nearest grid point as a new target grid point based on the new location of the first apparatus 110 and the information of the grid.

[0072] Then the first apparatus 110 may report (604), to the second apparatus 120, a new reference location report indicating an index (or indices) of the new target grid point. It is to be understood that the new reference location report may also indicate an offset or difference between the new target grid point and the target grid point previously reported.

[0073] Then the second apparatus 120 may further determine (606) a new location of the first apparatus 110 based on the new target grid point and the information of the grid. Similarly, the second apparatus 120 may further determine (608) the new TA between the first apparatus 110 and the second apparatus 120 based on the new determined location of the first apparatus 110.

[0074] After determining the new TA between the first apparatus 110 and the second apparatus 120, the second apparatus 120 may schedule the DL / UL transmission by using the new TA. Then the DL / UL transmission may be performed (610 and 612) between the first apparatus 110 and the second apparatus 120.

[0075] The data reported by the first apparatus 110, e.g., an index (or indices) of the nearest grid point, can be saved in the first apparatus 110 context for RRC mobility procedures. After the cell is handed over to a new satellite or after the first apparatus 110 goes into RRC Inactive state, the first apparatus 110 does not need to repeat the reference location reporting as long as the report is still valid. For example, when the first apparatus 110 transitions from Inactive state to Connected state, the network can use the reference location report in the first apparatus 110 context to calculate the TA for the first apparatus 110 when scheduling DL / UL transmissions. It is not imperative for the second apparatus 120 to know the TA when the first apparatus 110 is in Inactive state when no dynamic scheduling is performed for the first apparatus 110.

[0076] It is to be understood that a reference location report in RRC connected state does not require additional GNSS readings since first apparatus 110 is required to always have valid GNSS location data to maintain UL synchronization. In case of first apparatus 110 transmitting via SDT procedure in RRC Inactive state, the first apparatus 110 may need to acquire an updated GNSS location to calculate time and frequency compensation in UL. With the updated GNSS location, the first apparatus 110 may check if its location change has exceeded the threshold Dth and use SDT to send an reference location report update if needed. By giving network up-to-date information for TA calculation, potential collision between DL paging and UL SDT on pre-configured resources can be avoided.

[0077] In addition to the location change, the update of reference location report may also be triggered by other conditions, for example, a change of the target grid point value. If a change threshold associated with the target grid point value is configured by the second apparatus 120 and the first apparatus 110 determines that the change of the target grid point value exceeds the change threshold, a new reference location report may be triggered.

[0078] It is also possible that network can set the threshold (Dth or change threshold) based on the TA granularity parameter 8 or the grid point spacing d. For example, Dtll = k • c • 8, where c is the speed of light and k is a constant, or TAth = k • 8. Take the second apparatus 120’s time domain resource allocation being in the unit of 1ms for example, the threshold Dth can be safely set as large as 150 km (by considering the worst case of RTT change due to movement of this distance). For first apparatus 110 of low or medium mobility, a reference location report will stay valid for a very long period of time.

[0079] Overall, in this solution, the gNB in NTN sends information of grid and asks the UE to return feedback with respect to the provided data. From the UE feedback, gNB can derive a rough location of the UE and use it to calculate the satellite’s TA value for the UE for scheduling purposes.

[0080] The gNB may send to UE information of grid which consists of an orientation of the grid, the spacing of adjacent grid points and the origin of the grid. The UE may select a target grid point from the grid based on its location and report an indication of the target grid point to gNB.

[0081] The gNB may use the reported data and the information of grid to estimate the UE’s rough location using any trilateration method and use this estimated location to calculate the UE’s approximate service link TA when scheduling DL / UL resources for that UE. With the service link (i.e., satellite’s) TA knowledge, the gNB may avoid DL / UL conflict in HD-FDD operation.

[0082] It is to be understood that estimating the UE’s rough location using the RTT (multi-cell round trip time) or timing-based UL / DL (uplink / downlink) positioning methods is not feasible in NTN scenarios as the UE cannot obtain a minimum of three different measurements (e.g., positioning UL / DL measurements of UE Rx-Tx measurements) due to the wide rural coverage of gNBs in such deployments.

[0083] The network may add the reference location report or the UE’s rough location to the UE context in RRC (e.g. as a part of UE Inactive AS context). When the UE is handed over to a new satellite or goes into Inactive state, it does not need to repeat reference location reporting upon transitioning to RRC connected state with the new satellite.

[0084] The UE may trigger a reference location update if it has moved beyond a configured distance or if the target grid point value changes above a configured threshold.

[0085] With this solution, signaling overhead and power consumption associated with reference location reporting in NTN can be significantly reduced. It will greatly benefit loT devices deployed in remote areas and relying on NTN connectivity. In particular, for stationary devices, their location coordinates can be programmed, and the reference location report only needs to be sent once while they remain in RRC connected or inactive states.

[0086] Furthermore, in a case where the information of grid, especially the origin of the grid is made for UE specific, a higher level of security can be achieved. In this case, the reference position reported by the UE will not be known by other UEs in the cell. Even if the reference location report is intercepted by an eavesdropper, location of the UE cannot be determined without the origin of the grid. In this case, both gNB and UE should save the origin of the grid. The gNB may use the reported one or more indices of the target grid point and the grid information to calculate the UE’s location.

[0087] FIG. 7 shows a flowchart of an example method 700 implemented at a first 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 first apparatus 110 in FIG. 1.

[0088] At block 710, the first apparatus 110 receives, from a second apparatus, information of a grid of fixed locations via RRC signals or SDT procedure.

[0089] At block 720, the first apparatus 110 determines a target grid point in the grid associated with a reference location of the first apparatus.

[0090] At block 730, the first apparatus 110 generates, at least based on the target grid point, a reference location report including an indication associated with the target grid point.

[0091] At block 740, the first apparatus 110 transmits the reference location report to the second apparatus via RRC signals or SDT procedure.

[0092] In some example embodiments, the method 700 further comprises: determining, based on the information of the grid and a location of the first apparatus, a grid point nearest to the location of the first apparatus as the target grid point.

[0093] In some example embodiments, the information of the grid comprises an orientation of the grid and a spacing between two adjacent grid points.

[0094] In some example embodiments, the information of the grid comprises an origin of the grid, and wherein the origin of the grid is specified for a cell within which the first apparatus is located or specified for the first apparatus.

[0095] In some example embodiments, the indication associated with the target grid point comprises one or more indices of the target grid point.

[0096] In some example embodiments, a pre-determined TA granularity is associated with a spacing between two adjacent grid points.

[0097] In some example embodiments, the method 700 further comprises: receiving, from the second apparatus, a distance threshold associated with a mobility of the first apparatus; and in accordance with a determination that the first apparatus moves a distance exceeds the distance threshold, triggering the reference location report.

[0098] In some example embodiments, the method 700 further comprises: receiving, from the second apparatus, a change threshold associated with the target grid point value; and in accordance with a determination that a change of the target grid point value exceeds the change threshold, triggering the reference location report.

[0099] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a network device.

[0100] FIG. 8 shows a flowchart of an example method 800 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0101] At block 810, the second apparatus 120 transmits, to a first apparatus, information of a grid of fixed locations via RRC signals or SDT procedure.

[0102] At block 820, the second apparatus 120 receives, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus via RRC signals or SDT procedure.

[0103] At block 830, the second apparatus 120 determines a TA between the first apparatus and the second apparatus at least based on the reference location report.

[0104] In some example embodiments, the method 800 further comprises: obtaining, from the indication, one or more indices associated with the target grid point; determining a reference location of the first apparatus based on the one or more indices and the information of the grid; and determining the TA based on the reference location.

[0105] In some example embodiments, the method 800 further comprises: obtaining, from the indication, one or more indices of the target grid point; determining a reference location of the first apparatus based on the one or more indices and the information of the grid; estimating, based on the reference location, a round-trip time, RTT, between the first apparatus and a satellite serving the first apparatus; and determining the TA between the first apparatus and the second apparatus based on the RTT and a further TA between the second apparatus and the satellite.

[0106] In some example embodiments, a pre-determined TA granularity of the TA is associated with a spacing between two adjacent grid points.

[0107] In some example embodiments, the method 800 further comprises: indicating, to the first apparatus, a distance threshold associated with a mobility of the first apparatus and / or a change threshold associated with the target grid point value.

[0108] In some example embodiments, the distance threshold and / or the change threshold is configured based on a pre-determined TA granularity and / or a spacing between two adjacent grid points in the grid.

[0109] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a network device. (The method claims, MPF apparatus claims, and CRM claim will be drafted based on the above apparatus claims after they are approved.)

[0110] In some example embodiments, a first apparatus capable of performing any of the method 700 (for example, the first apparatus 110 in FIG. 1) 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 first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1. [011 l]In some example embodiments, the first apparatus comprises means for receiving, from a second apparatus, information of a grid of fixed locations; means for determining a target grid point in the grid associated with a reference location of the first apparatus; means for generating, at least based on the target grid point, a reference location report including an indication associated with the target grid point; and means for transmitting the reference location report to the second apparatus.

[0112] In some example embodiments, the first apparatus further comprises: means for determining, based on the information of the grid and a location of the first apparatus, a grid point nearest to the location of the first apparatus as the target grid point.

[0113] In some example embodiments, the information of the grid comprises an orientation of the grid and a spacing between two adjacent grid points.

[0114] In some example embodiments, the information of the grid comprises an origin of the grid, and wherein the origin of the grid is specified for a cell within which the first apparatus is located or specified for the first apparatus.

[0115] In some example embodiments, the indication associated with the target grid point comprises one or more indices of the target grid point.

[0116] In some example embodiments, a pre-determined TA granularity is associated with a spacing between two adjacent grid points.

[0117] In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, a distance threshold associated with a mobility of the first apparatus; and means for in accordance with a determination that the first apparatus moves a distance exceeds the distance threshold, triggering the reference location report.

[0118] In some example embodiments, the first apparatus further comprises: means for receiving, from the second apparatus, a change threshold associated with the target grid point value; and means for in accordance with a determination that a change of the target grid point value exceeds the change threshold, triggering the reference location report.

[0119] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a network device.

[0120] In some example embodiments, a second apparatus capable of performing any of the method 800 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 800. 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 first apparatus 110 in FIG. 1.

[0121] In some example embodiments, the second apparatus comprises means for transmitting, to a first apparatus, information of a grid of fixed locations; means for receiving, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; and means for determining a TA between the first apparatus and the second apparatus at least based on the reference location report.

[0122] In some example embodiments, the second apparatus further comprises: means for obtaining, from the indication, one or more indices associated with the target grid point; means for determining a reference location of the first apparatus based on the one or more indices and the information of the grid; and means for determining the TA based on the reference location.

[0123] In some example embodiments, the second apparatus further comprises: means for obtaining, from the indication, one or more indices of the target grid point; means for determining a reference location of the first apparatus based on the one or more indices and the information of the grid; means for estimating, based on the reference location, a round-trip time, RTT, between the first apparatus and a satellite serving the first apparatus; and means for determining the TA between the first apparatus and the second apparatus based on the RTT and a further TA between the second apparatus and the satellite.

[0124] In some example embodiments, a pre-determined TA granularity of the TA is associated with a spacing between two adjacent grid points.

[0125] In some example embodiments, the second apparatus further comprises: means for indicating, to the first apparatus, a distance threshold associated with a mobility of the first apparatus and / or a change threshold associated with the target grid point value. [() 1261In some example embodiments, the distance threshold and / or the change threshold is configured based on a pre-determined TA granularity and / or a spacing between two adjacent grid points in the grid.

[0127] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a network device. (The method claims, MPF apparatus claims, and CRM claim will be drafted based on the above apparatus claims after they are approved.)

[0128] FIG. 9 is a simplified block diagram of a device 900 that is suitable for implementing example embodiments of the present disclosure. The device 900 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1. As shown, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processor 910, and one or more communication modules 940 coupled to the processor 910.

[0129] The communication module 940 is for bidirectional communications. The communication module 940 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 940 may include at least one antenna.

[0130] The processor 910 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 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.

[0131] The memory 920 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) 924, 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) 922 and other volatile memories that will not last in the power-down duration.

[0132] A computer program 930 includes computer executable instructions that are executed by the associated processor 910. The instructions of the program 930 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 930 may be stored in the memory, e.g., the ROM 924. The processor 910 may perform any suitable actions and processing by loading the program 930 into the RAM 922.

[0133] The example embodiments of the present disclosure may be implemented by means of the program 930 so that the device 900 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 8. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0134] In some example embodiments, the program 930 may be tangibly contained in a computer readable medium which may be included in the device 900 (such as in the memory 920) or other storage devices that are accessible by the device 900. The device 900 may load the program 930 from the computer readable medium to the RAM 922 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).

[0135] FIG. 10 shows an example of the computer readable medium 1000 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1000 has the program 930 stored thereon.

[0136] 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.

[0137] 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 computerexecutable 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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

1. A first apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to:receive, from a second apparatus, information of a grid of fixed locations;determine a target grid point in the grid associated with a reference location of the first apparatus;generate, at least based on the target grid point, a reference location report including an indication associated with the target grid point; andtransmit the reference location report to the second apparatus.

2. The first apparatus of claim 1, wherein the first apparatus is caused to:determine, based on the information of the grid and a location of the first apparatus, a grid point nearest to the location of the first apparatus as the target grid point.

3. The first apparatus of claim 1 or 2, wherein the information of the grid comprises one or more of an orientation of the grid and a spacing between two adjacent grid points.

4. The first apparatus of any of claims 1-3, wherein the information of the grid comprises an origin of the grid, and wherein the origin of the grid is specified for a cell within which the first apparatus is located or specified for the first apparatus.

5. The first apparatus of any of claims 1-4, wherein the indication associated with the target grid point comprises one or more indices of the target grid point.

6. The first apparatus of any of claims 1-5, wherein a pre-determined TA granularity is associated with a spacing between two adjacent grid points.

7. The first apparatus of any of claims 1-6, wherein the first apparatus is caused to: receive, from the second apparatus, a distance threshold associated with a mobility of the first apparatus; andin accordance with a determination that the first apparatus moves a distance exceeds the distance threshold, trigger the reference location report.

8. The first apparatus of any of claims 1-6, wherein the first apparatus is caused to: receive, from the second apparatus, a change threshold associated with the target grid point value; andin accordance with a determination that a change of the target grid point value exceeds the change threshold, trigger the reference location report.

9. The first apparatus of any of claims 1-8, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a network device.

10. A second apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to:transmit, to a first apparatus, information of a grid of fixed locations;receive, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; anddetermine a TA between the first apparatus and the second apparatus at least based on the reference location report.

11. The second apparatus of claim 10, wherein the second apparatus is caused to: obtain, from the indication, one or more indices associated with the target grid point; determine a reference location of the first apparatus based on the one or more indices and the information of the grid; anddetermine the TA based on the reference location.

12. The second apparatus of claim 10, wherein the second apparatus is a ground station, and wherein the second apparatus is caused to:obtain, from the indication, one or more indices of the target grid point;determine a reference location of the first apparatus based on the one or more indices and the information of the grid;estimate, based on the reference location, a round-trip time, RTT, between the firstapparatus and a satellite serving the first apparatus; anddetermine the TA between the first apparatus and the second apparatus based on the RTT and a further TA between the second apparatus and the satellite.

13. The second apparatus of claim 11 or 12, wherein a pre-determined TA granularity of the TA is associated with a spacing between two adjacent grid points.

14. The second apparatus of any of claims 10-13, wherein the second apparatus is caused to:indicate, to the first apparatus, a distance threshold associated with a mobility of the first apparatus and / or a change threshold associated with the target grid point value.

15. The second apparatus of claim 13, wherein the distance threshold and / or the change threshold is configured based on a pre-determined TA granularity and / or a spacing between two adjacent grid points in the grid.

16. The second apparatus of any of claims 10-15, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a network device.

17. A method comprising:receiving, from a second apparatus, information of a grid of fixed locations;determining a target grid point in the grid associated with a reference location of the first apparatus;generating, at least based on the target grid point, a reference location report including an indication associated with the target grid point; andtransmitting the reference location report to the second apparatus.

18. A method comprising:transmitting, to a first apparatus, information of a grid of fixed locations;receiving, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; anddetermining a TA between the first apparatus and the second apparatus at least based on the reference location report.

19. A first apparatus comprising:means for receiving, from a second apparatus, information of a grid of fixed locations;5 means for determining a target grid point in the grid associated with a reference location of the first apparatus;means for generating, at least based on the target grid point, a reference location report including an indication associated with the target grid point; andmeans for transmitting the reference location report to the second apparatus.1020. A second apparatus comprising:means for transmitting, to a first apparatus, information of a grid of fixed locations;means for receiving, from the first apparatus, a reference location report including an indication associated with a target grid point selected by the first apparatus; and15 means for determining a TA between the first apparatus and the second apparatusat least based on the reference location report.

21. A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of claim 18 or the method of claim 19.

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