UE-initiated propagation delay compensation mechanism

Abstract

Methods, apparatuses, and computer programs for propagation delay compensation are provided. A method for a UE includes receiving a configuration to provide a propagation delay notification for a propagation delay estimate, determining when the notification should be sent, sending the propagation delay notification, and determining a corresponding action based on a configuration of a relationship between an uplink reference signal and a downlink reference signal. Methods for a radio node, such as a base station, are also provided.

Description

Technical Field

[0001] The exemplary and non-limiting embodiments generally relate to communications, and more specifically to a propagation delay compensation mechanism initiated by the UE. Background Technology

[0002] It is known how to synchronize communication between user equipment and radio nodes in a wireless network. Summary of the Invention

[0003] The following description of the invention is intended to be illustrative only. This description is not intended to limit the scope of the claims.

[0004] One example method includes receiving configuration to provide a propagation delay notification for a propagation delay estimate; determining when the notification should be sent; sending the propagation delay notification; and determining a corresponding action based on a configuration of the relationship between an uplink reference signal and a downlink reference signal.

[0005] Another example method includes providing a configuration for providing a propagation delay notification for a propagation delay estimate; and receiving the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0006] An example apparatus includes at least one processor; and at least one non-transitory memory, including computer program code; wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to perform at least: receiving a configuration for providing a propagation delay notification for a propagation delay estimate; determining when the notification should be sent; sending the propagation delay notification; and determining a corresponding action based on a configuration for the relationship between an uplink reference signal and a downlink reference signal. Attached Figure Description

[0007] The foregoing aspects and other features are explained in the following description in conjunction with the accompanying drawings, in which:

[0008] Figure 1 This is a block diagram of a possible non-limiting system in which example embodiments can be practiced.

[0009] Figure 2 This is a high-level flowchart of the propagation delay estimation mechanism initiated by the UE.

[0010] Figure 3 This is an example of a mapping table between UL_Ref and DL_Ref.

[0011] Figure 4 This is a flowchart of PD compensation on the UE.

[0012] Figure 5This is a flowchart of PD compensation on RAN nodes (e.g., gNB).

[0013] Figure 6 It is an example device configured to implement a propagation delay compensation mechanism based on the examples described herein.

[0014] Figure 7 An example method for implementing a propagation delay compensation mechanism based on the examples described in this paper is shown.

[0015] Figure 8 Another example method for implementing a propagation delay compensation mechanism based on the example described in this paper is shown. Detailed Implementation

[0016] The following acronyms and abbreviations, which can be found in the instruction manual and / or accompanying drawings, are defined as follows:

[0017] 3GPP: Third Generation Partnership Project

[0018] 4G: Fourth Generation

[0019] 5G: Fifth Generation

[0020] 5GC: 5G Core Network

[0021] ACK: Confirmation

[0022] Alt: Alternative Solution

[0023] AMF: Access and Mobility Management Functions

[0024] AoA: Angle of Arrival

[0025] A-SRS: Non-periodic SRS

[0026] BW: Bandwidth

[0027] CE: Control Element

[0028] CG: Configuration Authorization

[0029] CN: Core Network

[0030] CP: Cyclic prefix

[0031] CSI: Channel State Information

[0032] CU: Central Unit or Centralized Unit

[0033] DCI: Downlink Control Information

[0034] DL: Downlink

[0035] DL_Ref: Downlink reference signal

[0036] DMRS or DM-RS: Demodulation reference signal

[0037] DU: Distributed Unit

[0038] DSP: Digital Signal Processor

[0039] E-CID: Enhanced Cell ID; eNB: Evolved Node B (e.g., LTE base station).

[0040] EN-DC: E-UTRA-NR Dual Connection

[0041] en-gNB: A node that provides NR user plane and control plane protocol termination to the UE and acts as a secondary node in EN-DC.

[0042] E-UTRA: Evolved Universal Terrestrial Radio Access, i.e., LTE radio access technology.

[0043] F1: Control interface between CU and DU

[0044] FFS: For further research

[0045] FS_: Rel-17 Research

[0046] gNB: A base station used for 5G / NR, i.e., a node that provides NR user plane and control plane protocol termination to the UE and connects to the 5GC via the NG interface.

[0047] GPS: Global Positioning System

[0048] HARQ: Hybrid Automatic Repeat Request

[0049] I / F: Interface

[0050] ID: Identifier

[0051] IE: Information Elements

[0052] I / O: Input / Output

[0053] IoT: Internet of Things

[0054] IIoT: Industrial Internet of Things

[0055] LCH: Logical Channel

[0056] LMF: Location Management Function

[0057] LPP: LTE Location Protocol

[0058] LTE: Long Term Evolution (4G)

[0059] MAC: Media Access Control

[0060] MME: Mobility Management Entity

[0061] MSG2: Message 2 in a two-step RACH; MSG4: Message 4 in a four-step RACH.

[0062] Multiple RTT (Round-Trip Time): Multiple Cell Round-Trip Time; NAS (Non-Access Layer): Non-Access Layer

[0063] ng or NG: the new generation

[0064] ng-eNB: Next-generation eNB; NG-RAN: Next-generation radio access network

[0065] NLOS: Non-Line of Sight

[0066] NR: New Radio (5G)

[0067] NRPPa: New Radio Positioning Protocol; AN / W or NW: Network

[0068] PD: Propagation Delay

[0069] PDCP: Packet Data Convergence Protocol

[0070] PHY: Physical Layer

[0071] PRS: Positioning Reference Signal

[0072] P-SRS: Periodic SRS; SRSPUCCH: Physical Uplink Control Channel; PUSCH: Physical Uplink Shared Channel; R#: 3GPP RAN# / R# (3GPP working group or version); RACH: Random Access Channel.

[0073] RAN: Radio Access Network

[0074] RAN#: RAN WG# or radio layer#

[0075] RAR: Random Access Response

[0076] refSFN: System Frame Number Reference

[0077] Rel-: Version

[0078] RF: Radio Frequency

[0079] RLC: Radio Link Control

[0080] RP-: 3GPP RAN

[0081] RRC: Radio Resource Control

[0082] RRH: Remote Radio Header Terminal

[0083] RS: Reference signal

[0084] RSTD: Reference Signal Time Difference

[0085] RTC: Real-time Clock

[0086] RTT: Round Trip Time

[0087] RU: Radio Unit

[0088] Rx or RX: Receiver or interchangeable receiver

[0089] SA#: Services and Systems Working Group#

[0090] SCS: Subcarrier Spacing

[0091] SDAP: Service Data Adaptation Protocol

[0092] SGW: Service Gateway

[0093] SIB9: System Information Block 9, containing information related to GPS time and Coordinated Universal Time (UTC).

[0094] SIP: Session Initiation Protocol

[0095] SMF: Session Management Function

[0096] SPS: Semi-Permanent Scheduling

[0097] SR: Scheduling Request

[0098] SRS: Detection Reference Signal

[0099] SSB: Synchronization Signal Block

[0100] TA: Scheduled in advance

[0101] TAC: Timed Advance Command

[0102] ToD: Time of Day

[0103] TO: Timing Offset

[0104] TRP: Sending and Receiving Point

[0105] TSC: Time-Sensitive Communication (TSC)

[0106] TSN: Time-Sensitive Networking

[0107] Tx or TX: Transmitter or interchangeable transmitter

[0108] UCI: Uplink Control Information

[0109] UE: User Equipment (e.g., wireless equipment, typically mobile equipment)

[0110] UL: Uplink

[0111] UL_Ref: Uplink reference signal

[0112] UPF: User Plane Functionality

[0113] UTC: Coordinated Universal Time

[0114] Uu: Radio interface between mobile devices and the radio access network

[0115] WG: Working Group

[0116] Turn Figure 1 The figure illustrates a block diagram of one possible, non-limiting example in which examples can be practiced. It shows a user equipment (UE) 110, a radio access network (RAN) node 170, and (multiple) network elements 190. Figure 1 In the example, User Equipment (UE) 110 wirelessly communicates with Wireless Network 100. The UE is a wireless device that can access Wireless Network 100. UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected via one or more buses 127. Each of the one or more transceivers 130 includes a receiver Rx 132 and a transmitter Tx 133. The one or more buses 127 may be address, data, or control buses and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optic cable, or other optical communication device. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. UE 110 includes a module 140, which includes one or both of portions 140-1 and / or 140-2, and module 140 may be implemented in various ways. Module 140 may be implemented in hardware as module 140-1, such as as part of one or more processors 120. Module 140-1 can also be implemented as an integrated circuit or via other hardware such as a programmable gate array. In another example, module 140 can be implemented as module 140-2, which is implemented as computer program code 123 and executed by one or more processors 120. For example, one or more memories 125 and computer program code 123 can be configured, together with one or more processors 120, to cause user equipment 110 to perform one or more of the operations described herein. UE 110 communicates with RAN node 170 via radio link 111. Modules 140-1 and 140-2 can be configured to implement the functions of the UE as described herein.

[0117] In this example, RAN node 170 is a base station that provides access to wireless network 100 for wireless devices (such as UE 110). RAN node 170 can be, for example, a base station for 5G, also known as New Radio (NR). In 5G, RAN node 170 can be an NG-RAN node, which is defined as a gNB or ng-eNB. A gNB is a node that provides NR user plane and control plane protocol termination to the UE and is connected to the 5GC (e.g., multiple network elements 190) via an NG interface. An ng-eNB is a node that provides E-UTRA user plane and control plane protocol termination to the UE and is connected to the 5GC via an NG interface. An NG-RAN node can include multiple gNBs, which can also include a central unit (CU) (gNB-CU) 196 and multiple distributed units (DUs) (gNB-DU), where DU 195 is shown. Note that DU 195 can include or be coupled to and control a radio unit (RU). gNB-CU 196 is a logical node that hosts the Radio Resource Control (RRC), SDAP, and PDCP protocols of the gNB, or the RRC and PDCP protocols of the en-gNB that control the operation of one or more gNB-DUs. gNB-CU 196 terminates the F1 interface connected to gNB-DU 195. The F1 interface is shown as reference numeral 198, although reference numeral 198 also shows links between remote elements of RAN node 170 and centralized elements of RAN node 170, such as the link between gNB-CU 196 and gNB-DU 195. gNB-DU 195 is a logical node hosting the RLC, MAC, and PHY layers of the gNB or en-gNB, and its operation is partially controlled by gNB-CU 196. One gNB-CU 196 supports one or more cells. A cell is supported by only one gNB-DU 195. gNB-DU 195 terminates the F1 interface 198 connected to gNB-CU 196. Note that DU 195 is considered to include transceiver 160, for example, as part of an RU; however, some examples in this regard could allow transceiver 160 to be part of a separate RU, for example, under the control of and connected to DU 195. RAN node 170 could also be an eNB (evolved NodeB) base station for LTE (Long Term Evolution), or any other suitable base station or node.

[0118] RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / WI / F) 161 interconnected via one or more buses 157, and one or more transceivers 160. Each of the one or more transceivers 160 includes a receiver Rx 162 and a transmitter Tx 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. CU 196 may include one or more processors 152, one or more memories 155, and network interfaces 161. Note that DU 195 may also include its own memory / multiple memories and processors, and / or other hardware, but these are not shown.

[0119] RAN node 170 includes module 150, which includes one or both of portions 150-1 and / or 150-2. Module 150 can be implemented in various ways. Module 150 can be implemented in hardware as module 150-1, such as as part of one or more processors 152. Module 150-1 can also be implemented as an integrated circuit or via other hardware such as a programmable gate array. In another example, module 150 can be implemented as module 150-2, which is implemented as computer program code 153 and executed by one or more processors 152. For example, one or more memories 155 and computer program code 153 are configured, together with one or more processors 152, to cause RAN node 170 to perform one or more of the operations described herein. Note that the functionality of module 150 can be distributed, such as distributed between DU 195 and CU 196, or implemented solely in DU 195. Modules 150-1 and 150-2 can be configured to implement the functions of the base station described herein. Such functionality of the base station may include a location management function (LMF) implemented based on the functionality of the LMF described herein. This LMF may also be implemented as a location management component (LMC) within the RAN node 170.

[0120] One or more network interfaces 161 communicate over a network, such as via links 176 and 131. Two or more gNBs 170 may communicate using, for example, link 176. Link 176 may be wired, wireless, or both, and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interfaces for other standards.

[0121] One or more buses 157 may be address, data, or control buses and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fiber or other optical communication equipment, wireless channels, etc. For example, one or more transceivers 160 may be implemented as a Remote Radio Header (RRH) 195 for LTE or a Distributed Unit (DU) 195 for a gNB implementation for 5G, wherein other elements of the RAN node 170 may be physically located in a different location from the RRH / DU 195, and one or more buses 157 may be partially implemented as, for example, fiber optic cables or other suitable network connections for connecting other elements of the RAN node 170 (e.g., Central Unit (CU), gNB-CU) to the RRH / DU 195. Reference numeral 198 also indicates these suitable network links(s).

[0122] Note that the description in this document indicates that a "cell" performs a function; however, it should be clear that the equipment forming the cell can perform this function. A cell constitutes part of a base station. That is, each base station can have multiple cells. For example, a single carrier frequency and associated bandwidth can have three cells, each covering one-third of a 360-degree area, thus the coverage area of ​​a single base station is approximately elliptical or circular. Furthermore, each cell can correspond to a single carrier, and a base station can use multiple carriers. So if each carrier has three 120-degree cells and there are two carriers, the base station has a total of six cells.

[0123] Wireless network 100 may include one or more network elements 190, which may include core network functions and provide connectivity to other networks (e.g., the Internet) such as telephone networks and / or data communication networks via one or more links 181. Such core network functions for 5G may include location management functions (multiple LMFs) and / or access and mobility management functions (multiple AMFs) and / or user plane functions (multiple UPFs) and / or session management functions (multiple SMFs). Such core network functions for LTE may include MME (Mobility Management Entity) / SGW (Serving Gateway) functions. These are merely example functions that can be supported by the network elements 190, and note that both 5G and LTE functions can be supported. RAN node 170 is coupled to network element 190 via link 131. Link 131 may be implemented as, for example, an NG interface for 5G, or an S1 interface for LTE, or other suitable interfaces for other standards. Network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (multiple N / WI / F) 180 interconnected via one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and computer program code 173 are configured, together with the one or more processors 175, to cause network element 190 to perform one or more operations, such as the functionality of the LMF described herein. In some examples, a single LMF can serve a large area covered by hundreds of base stations.

[0124] Wireless network 100 can implement network virtualization, a process that combines hardware and software network resources and functions into a single software-based managed entity (virtual network). Network virtualization involves platform virtualization, which is often used in conjunction with resource virtualization. Network virtualization is divided into external network virtualization and internal network virtualization. External network virtualization combines many networks or network components into virtual units, while internal network virtualization provides network-like functionality to software containers on a single system. Note that the virtualized entities created by network virtualization are still implemented to some extent using hardware such as processors 152 or 175 and memories 155 and 171, and these virtualized entities also produce technical effects.

[0125] Computer-readable storage devices 125, 155, and 171 can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic storage devices and systems, optical storage devices and systems, fixed storage, and removable storage. Computer-readable storage devices 125, 155, and 171 can be means for performing storage functions. Processors 120, 152, and 175 can be of any type suitable for the local technical environment and, by way of non-limiting example, can include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Processors 120, 152, and 175 can be means for performing functions such as controlling UE 110, RAN node 170, network element(s) 190, and other functions described herein.

[0126] Typically, various embodiments of user equipment 110 may include, but are not limited to, cellular phones with wireless communication capabilities (such as smartphones, tablets, personal digital assistants (PDAs)), portable computers with wireless communication capabilities, image capture devices with wireless communication capabilities (such as digital cameras), gaming devices with wireless communication capabilities, music storage and playback devices with wireless communication capabilities, internet devices that allow wireless internet access and browsing, tablets with wireless communication capabilities, and portable units or terminals that combine such functions.

[0127] UE 110, RAN node 170, and / or (multiple) network elements 190 (and associated memory, computer program code, and modules) can be configured to implement a propagation delay compensation mechanism based on the examples described herein. Therefore, computer program code 123, module 140-1, module 140-2, computer program code 153, module 150-1, module 150-2, and / or computer program code 173 can be configured to implement a propagation delay estimation mechanism based on the examples described herein.

[0128] To support Industrial IoT use cases (IIoT), particularly Time-Sensitive Networking (TSN) or Time-Sensitive Communications (TSC) applications, accurate time synchronization is a supplement to Release 16 of the 3GPP 5G New Radio Specification. Time synchronization ensures that different nodes in a 5G network (e.g., UPF, gNB, UE) share the same time-of-day (ToD) clock, such as UTC. Time synchronization work continues in Release 17 as part of the FS_IIoT item in the SA2 Working Group (WG) and the NR_IIoT_URLLC_enh work item in the RAN WG.

[0129] Delivering time synchronization from the gNB to the UE via the Uu interface is challenging due to the dynamic nature of radio links. Using the 5G NR control plane, two methods can be used to deliver time synchronization information (i.e., the gNB clock) from the gNB to the served UE: one is a broadcast method, where the time information is encoded in a SIB9 message. SIB9 includes a timeInfo IE and a referenceTimeInfor16 IE, the former providing a 10μs Time-to-D granularity and the latter a 10ns Time-to-D granularity, which is crucial for the precise time synchronization use cases considered here. The other is a unicast method, where the time information is encoded in a unicast RRC message. In both methods, the encoded time information is the gNB clock time corresponding to the end boundary of a specific radio system frame (refSFN), where the refSFN is implicitly (in the broadcast case) or explicitly (in the unicast case) indicated to the UE. When the UE receives the SIB9 / RRC message, it associates the time information with its own refSFN boundary, which is aligned with the gNB's refSFN boundary. In this way, the underlying 5G radio frame timing at the gNB and UE is used as a common reference for ToD clock delivery.

[0130] One problem with using the underlying 5G radio frame timing at both the gNB and UE as a common reference for ToD clock delivery is that the radio frame boundaries (and therefore refSFN boundaries) at the gNB and UE are not perfectly aligned with each other in time. The downlink frame boundary at the UE is offset by the propagation delay relative to the corresponding frame boundary at the gNB (i.e., the time it takes for a radio frame to travel through the air from the gNB to the UE). When the UE synchronizes its clock by associating the timing information carried by the SIB9 / RRC message with its own refSFN boundary, its clock is delayed by the propagation delay compared to the gNB's clock. This might not be a problem if the propagation delay is relatively small compared to the maximum allowable timing error. However, given the maximum synchronization error on the 5G RAN and the distance between the UE and the gNB, which could cause the propagation delay alone to introduce a larger error, a mechanism is needed to compensate for this offset. Therefore, the UE needs to compensate for the propagation delay of the timing information received in the SIB9 / RRC message, for example, by adding its current PD estimate to the timing information.

[0131] During the discussions and evaluations conducted in RAN1 [e.g., R1-1900935], it was assumed that existing timing advance (TA) procedures could be used to obtain PD estimates. However, support for PD compensation in Release 16 was incomplete, as it did not specify how (through TA or a new procedure) PD estimates were obtained or by whom / what entity (UE or NW) applied PD compensation. These two issues still need to be addressed in Release 17. A strong reason behind the RAN2#109-e agreement is that, given other compelling arguments about how and by whom, some companies questioned the use of TA for PD compensation and wanted to investigate new procedures specifically for PD compensation (examples of such arguments can be found in [R2-2000786]).

[0132] As part of the NR positioning support introduced in Rel-16 (RP-190752), one positioning solution is multi-cell round-trip time (multi-RTT). In multi-RTT, the gNB transmits a downlink positioning reference signal (DL PRS), while in the uplink, the UE transmits a positioning reference signal (SRS). Based on these signals, the UE Rx-Tx time difference and the gNB Rx-Tx time difference are measured and then reported to the positioning server residing in the core network. The reporting and measurement configuration are accomplished using higher-layer signaling involving the core network. The Rx-Tx measurement measures the absolute time between receiving and transmitting the two reference signals (i.e., the UE Rx-Tx DL PRS reception and SRS transmission).

[0133] RTT / 2 is an alternative to TA / 2 for PD estimation, and both have their advantages and disadvantages. Using TA for PD estimation updates implies that the gNB has a frame timing reference, since the gNB otherwise cannot calculate TO and issue TAC based on UL transmission. This also means that using TA for other cells is not a suitable source for PD estimation. RTT / 2, on the other hand, does not have this requirement and is not limited by TA-related specifications and RAN4 requirements. Since both UL and DL reference signals are specified, this also means that the process does not require the gNB to have perfect timing estimation, thus making it suitable for non-serving cells. Another advantage is that RTT / 2 is not limited by TA performance requirements (e.g., TA adjustment accuracy) or TAC signaling granularity, and the reference signal can be allocated to minimize the UE's active time, which is beneficial from a power-saving perspective.

[0134] There are at least four problems with using TA for PD compensation, which can be addressed through the examples described / disclosed in this paper. Table 1 provides a summary of the problems and corresponding solutions disclosed in this paper.

[0135] Table 1. Problem and Solution Mapping

[0136]

[0137] Regarding question A, the current TA procedure applies to PUCCH, PUSCH, and SRS transmissions (both aperiodic and periodic). Measurements (timing offset (TO)) for UEs in the RRC_CONNECTED state are based on these signals and adjusted using a timing advance command (TAC) if necessary. If the UE is not configured with P-SRS, or has no UL or DL ​​data, these signals are unavailable, and therefore TAC is not possible. Furthermore, only the UE can track relative changes in DL timing to estimate the need for TA updates.

[0138] An analysis conducted in RAN1 in 2019 [R1-1900935] showed that timing advance for PD compensation can achieve an accuracy of approximately 340 ns in indoor factory deployments. In contrast, when TA is not used for PD compensation in comparable scenarios, the accuracy ranges from 215 ns to 415 ns, depending on the maximum considered distance to the gNB. Clearly, PD compensation is beneficial when the PD between the gNB and the UE is greater than a certain threshold, but below that threshold, it may actually carry additional errors. Part of this additional error stems from the specifications related to timing advance, the signaling granularity of the timing advance command (TE_TA-G, which introduces ±130 ns), and the requirements for applying timing advance (TA-err, which introduces ±130 ns).

[0139] Regarding question C, version 16 discusses which entity should apply PD compensation. Using timing advance as the basis for PD compensation, when the NW is responsible for PD compensation, it relies on its estimate of the TA applied by the UE. If needed, the UE has the ability to autonomously adjust the TA, and the gNB does not signal to the UE what TA it should apply.

[0140] Problem D arises because the TA procedure only applies to UEs in the RRC_CONNECTED state. A UE can receive SIB9 in RRC_INACTIVE or RRC_IDLE state, but to update the PD using TA, the UE needs to transition to RRC_CONNECTED, a signaling-intensive process just to obtain the new TAC and then transition back to RRC_INACTIVE or RRC_IDLE.

[0141] To address these issues, two overall approaches (or a combination thereof) can be chosen. Either enhance the TA process or introduce a new set of PD measurement and compensation mechanisms. A typical argument for the latter option is that TA is designed to keep UL transmit / receive times within CP (linearly scaled with SCS), while the target for time synchronization accuracy is on the order of hundreds of nanoseconds; therefore, it is a best-in-class solution for enhancing the timing advance process for precise time synchronization.

[0142] The baseline mechanism in version 16 uses advance timing for PD estimation and assumes that the UE can perform PD compensation. The version 16 baseline mechanism does not address any of issues A, B, C, and D.

[0143] LTE specifies an Enhanced CellID positioning method with RTT measurement (E-CID). In this method, TA is used to obtain the RTT measurement, which is then used to estimate the UE's location. Because it is TA-based, it has the same problems as TA (which are addressed in this paper). Therefore, E-CID does not address the identified problems (A, B, C, or D).

[0144] The 5G NR Release 16 Multi-RTT procedure (RP-190752) is a process for obtaining high-precision positioning estimates using multiple cells, suitable for cells with poor UE synchronization. However, it is not directly applied to time synchronization, and the measurements are not available to the UE and gNB, but are encapsulated in higher-layer signaling between the gNB / UE and the LMF. This also means that the procedure cannot solve the problems identified by the methods described in this paper, or only solves some problems in a signaling-intensive manner. More specifically, problem A can be solved by SIP, where the UE (which may host an LMF client (location client)) triggers a positioning update. From a synchronization point of view, the reference signal triggered by the LMF can be used to update the timing offset measurement, and thus trigger a TA update for a PD update. However, this is a very signaling-intensive solution. Problems C and D are not solved because the measurements cannot be provided to the UE, and the UE is unaware of the NW calculation. Problem B is solved, but the example in this paper significantly improves the signaling procedure, as signaling, and triggers the focus between the UE and its serving gNB. The 5G NR Release 16 Multi-RTT procedure involves multiple TRPs / gNBs, which is unnecessary for time synchronization—the examples described in this article consider enhancements that take advantage of this. In the case of UE to serving gNB, the RTT-based procedure still offers advantages over TA, as discussed in this article.

[0145] Another process involves configuring the gNB with SRS and DL-PRS / DL-DMRS. In this process, the gNB can configure the UE with periodic SRS and periodic PRS broadband signals to attempt to ensure high-precision time synchronization. If the period is high enough, allowing the PD to be updated frequently enough, this can be considered a workaround for problems A, B, and C and can work. However, this is also a resource-intensive method because it must be overly conservative in choosing a sufficiently low period. On the other hand, if it is not conservative enough, the UE still cannot indicate whether the PD is changing too quickly (problem A). Therefore, this solution is considered not a suitable one.

[0146] Therefore, the example described in this paper introduces a PD compensation framework that allows the NW to dynamically select the PD estimation technique and dynamically adjust configuration parameters to suit the accuracy provided to the UE. This framework supports RTT-based PD estimation techniques known from positioning, but is tailored here for time synchronization rather than positioning, as the process is changed to a single cell and features new low signaling overhead, activation mechanisms, and a semi-static relationship between the UL reference signal and the DL reference signal (this combination can be dynamically selected by the NW). This mechanism allows a capable UE to notify the gNB when it needs a PD estimation update. Since the UE can ultimately have PD estimates from both RTT and TA, a selection / prioritization mechanism is included in this framework.

[0147] Using this PD estimation framework, extensions to the method can be considered, including NW-based accuracy estimation to determine the required reference signal configuration, and estimation techniques regarding the benefits of reference signal burst-based and multi-cell time synchronization.

[0148] Figure 2 The high-level flowchart of this method is provided. The method consists of three main parts: the first part is initialization 200-1 (for each serving cell), the second part is reference signal activation 200-2 (for each serving cell), and the third part is PD estimation and compensation 200-3. These three main parts are described below.

[0149] In initialization 200-1, the NW determines whether the PD estimation framework should be configured to support RTT-based PD estimation techniques or reside on the target UE's TA. This decision can be made based on the required time synchronization accuracy (assuming the TA and RTT are designed for individual accuracy and the TA procedure is not optimized for time synchronization) and UE capabilities. Initialization can be performed on a per-serving-cell basis.

[0150] gNB 170 configures UE 110 (in Figure 2In 201, or Item 1), PD_notify (in 202-2, Item 2.b) is provided as part of the UCI framework, allowing it to indicate to gNB 170 that it deems a PD estimate update necessary. In other embodiments, PD_notify configuration 201 is provided as (SR (Reserved LCH), Special CG, New MACCE, New RRC message, New NAS message, or MSG2 / 4 added to RACH). In another embodiment, the PD_notify message is extended to also provide burst requests and expected periods. In an alternative embodiment, gNB 170 triggers a PD estimate update, for example, based on a mobility event or timer expiration (without using PD_notify).

[0151] If UE 110 is configured for PD_notify, then gNB 170 provides UE 110 with a PD_threshold at 201, which UE 110 uses to determine whether a PD_notify request is needed 202-2 (Item 2.b). This is a fixed value provided by gNB 170 (it can be fixed or semi-static; however, it is determined by gNB). In another embodiment, the PD threshold is determined by gNB 170 based on accuracy budget and UE mobility event statistics.

[0152] If an RTT-based approach is supported, the gNB 170 configures both the UL SRS and DL PRS reference signals at 201, along with the indexes between these configurations. This allows the gNB 170 to dynamically select configuration combinations. The indexes between configurations provide novelty because, through these configuration relationships, the gNB can manage configurations used together and can manage whether a TA-based or RTT-based approach is used.

[0153] UE 110 is configured to perform PD compensation on the ToD timestamp using the acquired PD estimate. In an alternative embodiment, NW can also be configured to perform PD compensation on the ToD timestamp using the acquired PD estimate.

[0154] During initialization, the configuration 201 of the UL and optional DL reference signals utilizes the specifications for A-SRS, P-SRS, and DL-PRS. However, to reference a specific DL reference signal (which may also be an SSB), the examples described herein introduce a DL RS index, allowing multiple options for referencing the DL RS in this method (e.g., refer to 203-12). Examples of the UL_Ref table and DL_Ref table are shown in Tables 2 and 3, respectively.

[0155] Table 2. Examples of UL_Ref configurations and indexes

[0156]

[0157]

[0158] Table 3. Examples of DL_Ref configurations and indexes

[0159] 0 DL-PRS ID 0 1 DM-RS (Preamble Index 1) 2 SSB Index 3

[0160] The examples in this document provide configurations for new propagation delay notification signals (e.g., PD_notify202-2 and / or PD notification configuration at 201). The following is a non-exhaustive list of options for implementing PD_notify (listed as AH).

[0161] A) Appending HARQ-ACK bits. PD_notify (201 and / or 202-2) can be carried within the HARQ-ACK codebook at either high or low priority (e.g., the priority introduced in R16) by retaining a specific bit index in the HARQ-ACK codebook. In this alternative, retaining this entry for each codebook is quite expensive for the codebook size. The overhead can be reduced using a periodic or "per second" mechanism.

[0162] B) Scheduling Request (via reserving the LCH). A scheduling request is used to indicate that there is data in the buffer of a specific logical channel. The existing framework of SR can be used for PD_notify by reserving logical channels (201 and / or 202-2) for PD_notify. This option can also be used for more than one bit of the PD_notify payload.

[0163] C) New UCI type. Similar to CSI reporting in the UCI framework, a set of PUCCH resources can be configured for PD_notify 202-2. This option will enable multiple bits for PD_notify.

[0164] D) Special Configured Grant (CG). The CG provides the UE with a framework for delivering user plane data from a pre-configured LCH within pre-configured resources, meaning it does not have to use the SR framework and wait for dynamic grant. One of these can be used to deliver PD_notify (201 and / or 202-2), for example by reserving the LCH or by dedicating that CG to C-plane messages (e.g., MAC CE). This alternative can also be used for UEs in the RRC_IDLE or RRC_INACTIVE state, as the CG can be used from RRC_INACTIVE version 17.

[0165] E) New MAC Control Element (CE) Types. gNBs and UEs use MAC CEs to deliver and request basic information related to the MAC layer. This could be, for example, a buffer status report or a power headroom report. Therefore, a new type carrying PD_notify (201 and / or 202-2) can be defined. This approach is also a good option for PD_notify with more than one bit.

[0166] F) New RRC Message. Defining a new RRC message is another option. While this is a slightly slower option, it is easier to scale in the future and can carry a larger payload.

[0167] G) New NAS messages are another option.

[0168] H) Add a new field in message 2 (for two-step RACH) or message 4 (for four-step RACH). This option is particularly useful for the mechanism working from RRC_INACTIVE or RRC_IDLE.

[0169] PD_threshold can be used to trigger PD_notify (201 and / or 202-2). The NW can configure PD_threshold using a range of parameters. In one example, PD_threshold is pre-configured at installation time. The NW can also know the time synchronization requirements (from the CN) and create a time inaccuracy budget for the components involved. Ultimately, the NW can roughly estimate the required margin and then estimate the response time of PD_threshold. It should be noted that this budget also needs to consider UE mobility history (e.g., fast-moving UEs may have a smaller threshold to trigger more frequent updates to the PD estimate) and deployment scenario (e.g., wide-area or small indoor deployment).

[0170] The configuration used for reporting Rx-Tx measurements (i.e., the UE Rx-Tx time difference if DL RS is included) can be included as part of PD_notify. For the UE to report UE Rx-Tx, this can be done via a UCI framework (such as CSI), a special CG, or a new RRC message. If no special resource is configured, the gNB can request measurements using, for example, a new MAC CE. For the gNB to report gNB Rx-Tx, this can be done using a new MAC CE, a special SPS configuration, or a new RRC message.

[0171] The examples described in this document provide a configuration for the relationship between UL reference signals and DL reference signals. Specifically, when configuring a set of UL reference signals and DL reference signals, the relationship between them (UL_Ref signal and DL_Ref signal) is also configured. This can be achieved using a mapping matrix that indicates which DL_Ref index can be used when configuring a particular UL_Ref. Figure 3 An example is provided. If a single UL_Ref can be mapped to multiple DL_Refs, the most recently received DL_Ref is used as the reference for the Rx-Tx measurement. Figure 3 In the example mapping matrix, UL_Ref 0 is mapped to / related to DL_Ref 0, UL_Ref 1 is mapped to / related to DL_Ref 2, and UL_Ref 2 is mapped to / related to DL_Ref 0.

[0172] By comparing the instantaneous PD estimate (estimated as PD_current by UE 110) with the previously provided PD value (PD_previous) and the change threshold PD_threshold in 202-1 (Item 2.a), UE 110 activates the new PD estimation procedure in 200-2. Specifically, UE 110 determines PD_current > |PD_previous - PD_threshold|. In an alternative implementation, this step is skipped, and the procedure is triggered by gNB 170 (e.g., by activating the UL reference signal configuration with DL reference signal relationships). Reference signal activation can be per serving cell.

[0173] Following the triggering of this process, UE 110 sends an SRS in response to the DL reference signal. By checking whether the PD estimation method has a configured relationship between the UL reference signal and the DL reference signal associated with the received DL reference signal, UE 110 can determine the expected gNB 170 response. If UE 110 is configured to have a configured relationship between the UL reference signal and the DL reference signal, it autonomously initiates Rx-Tx measurements for the signal with the pre-configured relationship. If no relationship exists, the UE expects conventional timing advance.

[0174] This mechanism triggers based on the UE's monitoring of DL PD changes, and if the UE 110 detects PD_current>|PD_previous-PD_threshold| (ref 202-1), then PD_notify 202-2 is signaled.

[0175] Upon receiving PD_notify 202-2, gNB 170 performs the following steps 1-2: 1) Determine which UL_Ref should be activated. This can be based, for example, on an estimate of the required precision (e.g., from the additional payload in PD_notify 202-2). 2) Send an activation signal for the UL_Ref (at 203-21). This can be accomplished in several ways, including the existing DCI format currently used to activate A-SRS, the existing RRC framework used to configure P-SRS, a new or extended DCI format / field designed to carry UL_Ref indications (e.g., the SRS resource indicator can be extended to cover, for example, 8 or 16 UL_Ref indices), or a new RRC message.

[0176] In alternative embodiment 203-1, the gNB 170 initiates the process, for example, by activating an SRS configuration configured with a corresponding DL reference. This is advantageous when the gNB 170 estimates that the need for a PD update is urgent (e.g., prior to a mobility event).

[0177] If UE 110 is configured with at least one DL_Ref, then UE 110 performs the following actions: looks up in the table which DL_Ref indexes are associated with the UL_Ref index; if there is more than one DL_Ref, then the UE selects (at 203-12) its first configured DL_Ref (e.g., in chronological order); the UE measures the time between receiving the DL_Ref at time T4 and sending its UL_Ref at time T1 at 203-14.

[0178] When acquiring Rx-Tx measurements, a corresponding entity needs to be provided to the entity responsible for PD compensation (at 203-16). If gNB 170 is responsible for PD compensation, the Rx-Tx measurement 203-14 is delivered from UE 110 to gNB 170. Implementation options for this include: a new MAC CE, which is a concept similar to PD_notify described in Part 1. Here, gNB 170 can request the measurement; a special CG reserved for Rx-Tx measurements (and possibly PD_notify); a new UCI report; a new RRC message; or a new NAS message.

[0179] When UE 110 is configured to perform PD compensation, a similar alternative can be considered, as it needs to receive Rx-Tx measurements 203-15 from gNB170, excluding CG.

[0180] Regarding PD estimation and compensation, if at least one DL reference signal is configured (refer to item 3.a, 203-1), UE110 and gNB170 perform Rx-Tx measurements (203-14 and 203-15, respectively). If UE110 is configured to perform PD compensation, gNB170 signals the Rx-Tx measurement 203-15 to UE110 at 203-16. This can be a new MACCE or RRC message. If gNB170 (or NW) is configured to perform PD compensation, UE110 signals its Rx-Tx measurement 203-14 to gNB170 at 203-16. This can be a MAC CE or RRC message. gNB170 can also request this measurement 203-14. Further details regarding the methodological differences when gNB170 or UE110 is configured to perform PD estimation are provided herein. PD is estimated as, for example, RTT / 2 = ((T3-T2) + (T4-T1)) / 2 (according to...) Figure 2 ,Right now Figure 2 (T1, T2, T3, and T4 are shown in the figure). As further described herein, UE 110 selects between PD estimates (if multiple PD estimates are available).

[0181] If no DL reference signal is configured (refer to item 3.b, 203-2), UE 110 expects a timing adjustment message from gNB 170 at 203-24 (if needed). This adjustment message 203-24 can be a TAC, or it can be a new message (MAC or RRC). PD is estimated as cumulative timing adjustment. The new ToD is compensated by the latest PD measurement.

[0182] therefore, Figure 2 The signaling diagram 200 is shown, which includes Part 1 (Initialization 200-1), Part 2 (Reference Signal Activation 200-2), and Part 3 (PD Estimation and Compensation 200-3).

[0183] At 201, gNB 170 provides UE 110 with configurations for (multiple) UL reference signals, optional DL reference signals, PD notifications, and optional relationships between UL and DL reference signals. At 202-1, UE 110 determines whether PD_current is greater than the absolute value of PD_previous minus PD_threshold. At 202-2, UE 110 sends a PD_notify to gNB 170 in response to the positive determination at 202-1.

[0184] During period 203-2 (when no DL reference signal is configured), at 203-21, gNB 170 sends a UL_Ref activation signal to UE 110. At 203-22, UE 110 activates the UL_Ref configuration. At 203-23, UE 110 sends a UL Ref203-23 ​​signal to gNB 170. At 203-24, gNB 170 sends a timing adjustment message to UE 110.

[0185] During time 203-1 (when at least one DL reference signal is configured), gNB 170 sends DL_Ref (reference numeral 203-11) to UE 110 at time T2, and this DL_Ref is received by the UE at time T4. In time 203-12, UE 110 determines the corresponding DL_Ref to be used for measurement and activates UL_Ref. At time T1, UE 110 sends UL_Ref (reference numeral 203-13) to gNB 170, and this UL_Ref is received by gNB at time T3. In time 203-14, UE 110 calculates Rx-Tx, and in time 203-15, gNB calculates Rx-Tx. At positions 203-16, UE 110 and gNB 170 perform a measurement exchange; specifically, UE 110 sends the calculated Rx-Tx to gNB 170 at position 203-14, and / or gNB 170 sends the calculated Rx-Tx to UE 110 at position 203-15. At position 203-17, PD is calculated by UE 110 and / or gNB 170. At position 204, UE 110 and / or gNB 170 compensate for the ToD timestamp with the PD.

[0186] In respectively Figure 4 and Figure 5 The document provides flowcharts illustrating the scenarios where UE 110 and gNB 170 are performing PD compensation 200-3. These apply to cases where Rx-Tx measurements are available (at least one DL_Ref is configured, see [link]). Figure 2 (203-1).

[0187] exist Figure 4 and Figure 5 In this case, first calculate PD (item 203-17-item G). Then, if UE 110 is performing PD compensation, then in 206 ( Figure 4 Item H in the document (referring to a specific document or program) awaits reception of SIB9, which can be delivered in broadcast or unicast mode (via DLContentTransfer or RRCReconfiguration in version 16). In 208 (...), Figure 4In Project I), the UE 110 may then have two sources for PD estimation: Rx-Tx measurements (if available), such as RTT / 2; and TA procedures, such as TA / 2, and must combine these sources or use only one of them. This choice can be pre-configured or left to the UE implementation to select. Options are shown in the following AD:

[0188] A) UE 110 uses the latest possible source (at 208, Alt 1, the latest). This is a simple configuration, but it may not be optimal or accurate because the measurement may be affected by fading. However, if the latest measurement is the result of another configuration, such as a reference signal with a smaller bandwidth, it is also simple, but therefore may be less accurate.

[0189] B) UE 110 uses RTT or TA. This is another simple configuration option, but it may make more sense because the gNB can estimate the accuracy of one source based on another.

[0190] C) UE 110 uses a source with the highest estimation accuracy. Accuracy can be estimated through the time tracking algorithm, the bandwidth used for the reference signal, and the granularity of the measurement.

[0191] D) UE 110 combines two sources. If UE 110 uses a time-tracking algorithm, it can switch between these two sets of measurements, or combine them based on the fundamental idea that they are trying to measure the same thing. It may be necessary to weight one source differently than the other, for example, based on its expected accuracy.

[0192] Therefore, as Figure 4 As further shown, when the UE performs PD compensation 200-3, at 203-17, UE 110 calculates PD as RTT / 2 = ((T3-T2)+(T4-T1)) / 2. At 206, gNB 170 sends SIB9 or delivers DLContentTransfer(RRC) of timeInfo+referenceTimeInfo IE. At 208, the UE prioritizes PD source TA / 2 and RTT / 2. Alternatives shown at 208 are Alt 1 (using the latest) 208-1, Alt 2 (prioritizing RTT PD estimates) 208-2, and Alt 3 (using the priority configured by gNB) 208-3. At 220 ( Figure 4 In Project J), UE110 sets RTC to timeInfo+PD.

[0193] When the gNB 170 performs PD compensation 200-3, it can also have two PD estimation sources. However, due to the uncertainties explained above, it should be clear that if the Rx-Tx measurement is available, it should be used as the PD reference on the gNB 170 (see [link to relevant documentation]). Figure 5 Project 210-Project I). Then, in 211, gNB 170 needs to be generated. Figure 5 UE-specific SIB9 message 212-item I1 (or to a group of UEs with sufficiently similar PDs).

[0194] In alternative implementation 215, gNB 170 in 216 ( Figure 5 Project I2) sends a signal to UE 110 to notify PD (new signal), which enables gNB 170 to use broadcast mode 218 ( Figure 5 Project H) in the project is distributed as SIB9.

[0195] Therefore, as Figure 5 As further shown, when gNB 170 performs PD compensation 200-3, at 203-17, gNB 170 calculates PD = RTT / 2 = ((T3-T2)+(T4-T1)) / 2. At 210, gNB 170 selects the most accurate PD source, such as the PD source with the lowest jitter. For unicast at 211, gNB 170 adds the PD to the UE-specific 5G timestamp provided to gNB CU 196 (for unicast) at 212, and at 214 ( Figure 5 At point 211 (H), gNB 170 provides a DLContentTransfer (RRC) signal to UE 110. At point 215, gNB 170 signals PD (for broadcasting) to UE 110 at point 216, and at point 218, gNB 170 signals DLContentTransfer (RRC) transmission for SIB9 or timeInfo+referenceTimeInfo IE. At point 220 ( Figure 5 In Project J), UE 110 sets RTC to timeInfo+PD.

[0196] In summary, the examples described herein illustrate the configuration of the relationship between PD_notify signals (including 202-2), Rx-Tx measurement reports 203-16 from gNB to UE and / or from UE to gNB outside of the positioning protocol, the UL and DL reference signal indexes for activating the configuration signals, the mixing of various configurations (as further described herein), and the selection mechanism for the PD estimation mechanism.

[0197] The examples in this document further provide implementations of UE mechanisms (collectively referred to as 201, 203-1, and 203-2) to determine the relationship between the UL reference signal and the DL reference signal, UE measurement filtering for triggering PD_notify 202-2 (e.g., 202-1), NW system optimization for the relationship between the UL reference signal and the DL reference signal—e.g., based on desired accuracy, NW algorithms for determining the optimal PD_threshold (e.g., based on accuracy budget and UE mobility characteristics), and extensions from UE 110 to PD_notify 202-2 (e.g., the desired period of action corresponding to gNB 170, measurement burst, or current accuracy (see embodiments further described herein)).

[0198] The examples in this paper provide numerous advantages, benefits, and technical effects. These include providing methods for addressing problems A, B, C, and D. They also include avoiding the core network signaling required for Rx-Tx measurements (e.g., via LPP or NRPPa). Furthermore, the examples described in this paper allow the NW to more accurately select the resources for reference signals used for synchronization based on UE feedback. Without this, the NW would have to be conservative (e.g., by selecting too frequent and too high bandwidths) in hopes of achieving synchronization accuracy. Moreover, the examples described in this paper are flexible enough to be applied to multi-cell scenarios to leverage PD estimation and compensation for multiple cells.

[0199] The additional embodiments can be viewed as adaptations to specific scenarios, namely additional embodiments 1-4.

[0200] Additional Example 1 relates to a serving UE in RRC-IDLE or RRC-INACTIVE states. The examples described herein can be configured for use with UEs in RRC-IDLE or RRC-INACTIVE states as well. The PD_notify signal can be configured via a special CG or as part of a RACH procedure. The delivery of measurements then needs to be configured via a special CG (for UL) or short data transmission (e.g., two-step RACH). As part of this example, the UE can be configured with DL PRS from multiple cells, which the UE periodically measures to calculate RSTD when in RRC-IDLE or RRC-INACTIVE states. Monitoring these RSTD measurements can be used as an alternative trigger for sending PD_notify (i.e., sending PD_nnotify if the RSTD change exceeds a threshold).

[0201] The steps involved in Additional Implementation 1 are: The optional scheme of using relevant UL and DL RS links is important for unconnected UEs (i.e., it cannot be assumed that DL is being listened to); (optionally) aligning the DL reference with SIB9 to minimize UE wake-up time; (optionally) using a high-precision DL reference in conjunction with the UL reference to reduce the need for multiple measurements; here, preferably, PD_notify is used in RACH or CG. If the NW is responsible for PD estimation, the CG can also perform Rx-Tx measurements; the UE can be configured with DL PRS from multiple cells, which the UE periodically measures to calculate RSTD when in RRC-IDLE or RRC-INACTIVE state. Monitoring these RSTD measurements can be used as an alternative to or additional trigger for PD_notify.

[0202] Additional Example 2 relates to an extension of PD_notify (greater than 1 bit). PD_notify can be configured in different formats. The simplest is a single-bit signal. Possible extensions are AB:

[0203] A) The UE signals its expected or current accuracy, or quantifies the expected and current accuracy into an emergency indicator. The gNB can use this indicator to select the corresponding DL_Ref and UL_Ref to achieve the desired accuracy. It can also be used to determine whether new reference signals (RS) should be configured and their expected frequencies. This can be an explicit report of accuracy or an implicit metric used to estimate accuracy, such as current timing advance or PD_current, which the gNB can compare to the expected accuracy.

[0204] B) The configuration format of PD_notify can include a request for an updated expected period or a number of measurements to enhance stability (measurement burst). Thus, the NW can configure the BW burst of the reference signal accordingly. This is particularly relevant when the UE wakes up from RRC_IDLE or has just entered a new cell. In these cases, this may indicate that the UE has a less accurate DL timing reference, and the gNB has little or no TO measurements. In these cases, performing multiple measurements in a short period helps the filter converge. This embodiment can be implemented simply using existing frameworks, but with the gNB activating UL_Ref multiple times. This can also be achieved by the gNB embedding a "reproduce" indicator in the UL_Ref signal.

[0205] The advantage of these options is that they all enhance the gNB options to help the UE ensure that accuracy requirements are met without unnecessary resource and power consumption.

[0206] Additional embodiment 3 relates to multiple RTTs to further enhance timing accuracy from multiple neighboring cells. The described method can be easily extended to neighboring cells, where the use of linked DL and UL reference signals is necessary because the UE may not be accurately synchronized to neighboring cells. In this case, the UE should perform PD compensation. This embodiment can provide diversity for PD compensation (if a measurement is poor, for example, due to NLOS), ensure faster convergence of the filter, or improve accuracy by utilizing SIB9, which can be individually encoded so that rounding errors can be averaged.

[0207] It is assumed that the method described in this paper can be applied to each serving cell. Activation of the UL_Ref can be performed from the primary cell to another serving cell. The PD_notify signal can remain directed toward the primary gNB. Triggering can also be directed to other cells, in which case the cell ID is added to the PD_notify. Rx-Tx measurements can be performed through the primary gNB, allowing the measurement message to be expanded to capture measurements from multiple cells.

[0208] In an alternative implementation, RTT measurements are collected by (e.g., by the LMF of gNB 170) but delivered to UE 110. ToD is sent from multiple neighboring cells. The UE estimates the refSFN for each neighboring cell. PD estimates are obtained from each neighboring cell. ToD is compensated for with each PD estimate. As in Additional Embodiment 1, the UE may be configured with DL PRS from multiple cells, which the UE periodically measures to calculate RSTD. Monitoring these RSTD measurements can be used as another trigger for PD_notify.

[0209] Additional Example 4 relates to the UE automatically disabling the reference signal when it no longer receives SIB9. In cases using periodic reference signals, the gNB would have to disable each configuration when the UE no longer needs SIB9. If the UE automatically disables the configuration when it no longer receives SIB9, signaling can be saved.

[0210] Figure 6This is an example device 600, which can be implemented in hardware. Device 600 is configured to implement propagation delay compensation based on the examples described herein. Device 600 includes a processor 602 and at least one non-transitory memory 604 including computer program code 605, wherein the at least one memory 604 and the computer program code 605 are configured, together with at least one processor 602, to cause the device to implement circuitry, processes, components, modules, or functions (collectively, 606) for implementing propagation delay (PD) compensation. Device 600 optionally includes a display and / or I / O interface 608, which can be used to display aspects or states of the methods described herein (e.g., while the method is being executed or at a subsequent time). Device 600 includes one or more network (NW) interfaces ((multiple) I / F) 610. The (multiple) NW I / F 610 can be wired and / or wireless and communicate over the Internet / (multiple) other networks via any communication technology. (Multiple) NW I / F 610 may include one or more transmitters and one or more receivers.

[0211] Device 600 may be UE 110, RAN node 170, or (multiple) network elements 190. Therefore, processor 602 may correspond to (multiple) processors 120, (multiple) processors 152, or (multiple) processors 175; memory 604 may correspond to (multiple) memory 125, (multiple) memory 155, or (multiple) memory 171; computer program code 605 may correspond to computer program code 123, module 140-1, module 140-2, computer program code 153, module 150-1, module 150-2, or computer program code 173; and (multiple) N / WI / F 610 may correspond to (multiple) N / WI / F 161 or (multiple) N / WI / F 180. Alternatively, device 600 may not correspond to any of UE 110, RAN node 170, or (multiple) network elements 190 (e.g., device 600 may be a remote, virtual, or cloud device).

[0212] References to "computer," "processor," etc., should be understood to include not only computers with different architectures (such as single / multiprocessor architectures and sequential (von Neumann) / parallel architectures), but also special-purpose circuits, such as field-programmable gate arrays (FPGAs), special-purpose circuits (ASICs), signal processing devices, and other processing circuit systems. References to computer programs, instructions, code, etc., should be understood to encompass the software of programmable processors or firmware, such as the programmable content of hardware devices, whether it is the processor's instructions or the configuration settings of fixed-function devices, gate arrays, or programmable logic devices.

[0213] The memory 604 can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The memory 604 may include a database for storing data.

[0214] As used in this application, the term "circuit system" refers to all of the following: (a) hardware circuitry implementations only, such as implementations only in analog and / or digital circuitry systems; and (b) combinations of circuitry and software (and / or firmware), such as (if applicable): (i) combinations of (multiple) processors, or (ii) portions of (multiple) processors / software, including (multiple) digital signal processors, software, and (multiple) memories, which work together to cause the device to perform various functions; and (c) circuitry that requires software or firmware to operate, such as (multiple) microprocessors or portions of (multiple) microprocessors, even if the software or firmware is not physically present. The definition of "circuit system" applies to all uses of the term in this application. As another example, as used in this application, the term "circuit system" will also cover implementations of only one processor (or multiple processors) or portions of a processor and its accompanying software and / or firmware. For example, if applicable to a particular element, the term "circuit system" will also cover baseband integrated circuits or application processor integrated circuits for mobile phones, or similar integrated circuits in servers, cellular network devices, or other network devices.

[0215] Figure 7 This is an example method 700 for implementing propagation delay compensation based on example embodiments described herein. At 702, the method includes receiving a configuration for providing a propagation delay notification for propagation delay estimation. At 704, the method includes determining when the notification should be sent. At 706, the method includes sending the propagation delay notification. At 708, the method includes determining a corresponding action based on a configuration of the relationship between an uplink reference signal and a downlink reference signal. Method 700 can be provided by, for example... Figure 1 UE 110 or Figure 6 The device 600 and other user equipment are executed.

[0216] Figure 8 This is another example method 800 for implementing propagation delay compensation based on the example embodiments described herein. At 802, the method includes providing a configuration for providing propagation delay notification for propagation delay estimation. At 804, the method includes receiving propagation delay notification. At 806, the method includes wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal. Method 800 can be provided by, for example... Figure 1 RAN node 170 or Figure 6 The device 600 and other radio nodes are used for execution.

[0217] One example method includes: receiving a configuration for providing a propagation delay notification for a propagation delay estimate; determining when the notification should be sent; sending the propagation delay notification; and determining a corresponding action based on a configuration relating an uplink reference signal and a downlink reference signal.

[0218] The method may further include sending an uplink reference signal to activate the propagation delay estimation.

[0219] The method may also include applying the propagation delay estimate to synchronize the user equipment throughout the day.

[0220] The method may further include receiving a timing adjustment message for the propagation delay estimate in response to at least one downlink reference signal not being configured.

[0221] The method may further include performing a user equipment receive and transmit timing difference measurement in response to at least one downlink reference signal being configured, and signaling the user equipment to the receive and transmit timing difference measurement, or receiving a radio node receive and transmit timing difference measurement for the propagation delay estimation.

[0222] The method may further include receiving a configuration of the relationship between the uplink reference signal and the downlink reference signal as an index; using the index to determine the at least one downlink reference signal to be used; and transmitting the uplink reference signal based on the determined at least one downlink reference signal to activate the propagation delay estimation.

[0223] The method may further include: wherein the configuration for providing the propagation delay notification includes a propagation delay threshold used to determine whether to provide the propagation delay notification; and providing the propagation delay notification in response to a current propagation delay estimate being greater than the difference between a previously provided propagation delay estimate and the propagation delay threshold.

[0224] The method may further include: wherein the propagation delay notification includes at least one burst request and / or expected period.

[0225] The method may further include selecting a propagation delay estimate when multiple propagation delay estimates are available; wherein the multiple propagation delay estimates include receive / transmit measurements and / or timing advance.

[0226] The method may further include estimating the propagation delay as a round-trip time (RTT).

[0227] The method may further include: wherein the RTT is a multi-RTT with measurements from neighboring cells.

[0228] The method may further include: the user equipment being idle or inactive; and the propagation delay notification being provided in response to a change in the reference signal time difference exceeding a threshold.

[0229] The method may further include: wherein the propagation delay notification is a multi-bit notification that includes the expected accuracy or expected period of the measurement update.

[0230] One example method includes: providing a configuration for providing a propagation delay notification for a propagation delay estimate; and receiving the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0231] The method may further include receiving an uplink reference signal to activate the propagation delay estimation.

[0232] The method may further include: wherein the estimated propagation delay is applied to synchronize the time of day.

[0233] The method may further include providing a timing adjustment message for the propagation delay estimation in response to at least one downlink reference signal not being configured.

[0234] The method may further include performing a radio node receive and transmit timing difference measurement in response to at least one downlink reference signal being configured, and signaling the radio node to the receive and transmit timing difference measurement, or receiving different receive and transmit timing difference measurements for the propagation delay estimate.

[0235] The method may further include sending the configuration of the relationship between the uplink reference signal and the downlink reference signal as an index; and receiving the uplink reference signal to activate the propagation delay estimation based on the index.

[0236] The method may further include: providing the propagation delay notification configuration includes providing a propagation delay threshold; and wherein the propagation delay notification is received in response to a current propagation delay estimate being greater than the difference between a previously provided propagation delay estimate and the propagation delay threshold.

[0237] The method may also include determining the propagation delay threshold based on at least one of accuracy budget and / or mobility event statistics.

[0238] The method may further include determining whether to provide the propagation delay notification configuration for the propagation delay estimation or to send the uplink reference signal configuration for the propagation delay estimation; wherein the determination is based on at least one of time synchronization accuracy requirements, device capabilities, mobility events, or timer expiration.

[0239] The method may further include: wherein the propagation delay notification includes at least one burst request and / or expected period.

[0240] The method may also include sending the propagation delay estimate.

[0241] The method may further include estimating the propagation delay as a round-trip time (RTT).

[0242] The method may further include: wherein the RTT is a multi-RTT with measurements from neighboring cells.

[0243] The method may also include broadcasting the propagation delay estimate.

[0244] The method may further include: wherein the propagation delay notification is received in response to a change in the reference signal time difference exceeding a threshold.

[0245] The method may further include: wherein the propagation delay notification is a multi-bit notification that includes the expected accuracy or expected period of the measurement update.

[0246] An example apparatus includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to perform at least: receiving a configuration for providing a propagation delay notification for a propagation delay estimate; determining when the notification should be sent; sending the propagation delay notification; and determining a corresponding action based on a configuration of the relationship between an uplink reference signal and a downlink reference signal.

[0247] An example device includes at least one processor; and at least one non-transitory memory including computer program code; wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the device to at least perform: providing a configuration for providing a propagation delay notification for a propagation delay estimate; and receiving the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0248] A machine-readable example non-transient program storage device may be provided, which tangibly embodies a machine-executable instruction program for performing operations including: receiving a configuration for providing a propagation delay notification for propagation delay estimation; determining when the notification should be sent; sending the propagation delay notification; and determining a corresponding action based on a configuration of the relationship between an uplink reference signal and a downlink reference signal.

[0249] A machine-readable example non-transient program storage device may be provided, which tangibly embodies a machine-executable instruction program for performing operations including: providing a configuration for providing a propagation delay notification for a propagation delay estimate; and receiving the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0250] An example apparatus includes circuitry configured to receive a propagation delay notification for providing a propagation delay estimate; circuitry configured to determine when the notification should be sent; circuitry configured to send the propagation delay notification; and circuitry configured to determine a corresponding action based on a configuration relating an uplink reference signal and a downlink reference signal.

[0251] An example apparatus includes circuitry configured to provide a propagation delay notification for providing a propagation delay estimate; and circuitry configured to receive the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0252] An example apparatus includes components for receiving a configuration for providing a propagation delay notification for a propagation delay estimate; components for determining when the notification should be sent; components for sending the propagation delay notification; and components for determining a corresponding action based on a configuration of the relationship between an uplink reference signal and a downlink reference signal.

[0253] An example apparatus includes components for providing a configuration for providing a propagation delay notification for a propagation delay estimate; and components for receiving the propagation delay notification; wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal.

[0254] It should be understood that the above description is illustrative only. Those skilled in the art can devise various alternatives and modifications. For example, the features recited in the various dependent claims can be combined with each other in any suitable combination. Furthermore, features from the different embodiments described above can be selectively combined to form new embodiments. Therefore, this specification is intended to cover all such alternatives, modifications, and variations falling within the scope of the appended claims.

Claims

1. A communication method, comprising: At the user equipment, a configuration is received to provide propagation delay notification for propagation delay estimation, wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal used as an index for propagation delay estimation. Determine when the notification should be sent; Send the aforementioned propagation delay notification; as well as Based on the relationship between the uplink reference signal and the downlink reference signal, the corresponding action for propagation delay estimation is determined. The method further includes: In response to the configuration of at least one downlink reference signal, the index is used to determine the at least one downlink reference signal to be used; as well as The uplink reference signal is transmitted based on at least one determined downlink reference signal to activate the propagation delay estimation.

2. The method of claim 1, further comprising sending an uplink reference signal to activate the propagation delay estimation.

3. The method of claim 1, further comprising applying the propagation delay estimate to synchronize the time of day of the user equipment.

4. The method according to claim 1, further comprising: Perform a timing difference measurement of the user equipment receiving and transmitting data, and signal the user equipment to notify the receiving and transmitting timing difference measurement, or receive a timing difference measurement of the radio node receiving and transmitting data for the propagation delay estimation.

5. The method according to claim 1, further comprising: The configuration for providing the propagation delay notification includes a propagation delay threshold used to determine whether to provide the propagation delay notification; as well as The propagation delay notification is provided in response to the current propagation delay estimate being greater than the difference between the previously provided propagation delay estimate and the propagation delay threshold.

6. The method of claim 1, wherein the propagation delay notification includes at least one burst request and / or expected period.

7. The method according to claim 1, further comprising: When multiple propagation delay estimates are available, the propagation delay estimate is selected; The aforementioned multiple propagation delay estimates include receive / transmit measurements and / or timing advance.

8. The method of claim 1, further comprising estimating the propagation delay as a round-trip time (RTT).

9. The method of claim 8, wherein the RTT is a multi-RTT with measurements from neighboring cells.

10. The method of claim 1, wherein: The user equipment is idle or inactive; and The propagation delay notification is provided in response to a change in the reference signal time difference exceeding a threshold.

11. The method according to any one of claims 1 to 10, wherein the propagation delay notification is a multi-bit notification including the expected accuracy or expected period of the measurement update.

12. A communication method, comprising: Provide a configuration for providing propagation delay notification for propagation delay estimation; as well as Receive the propagation delay notification; The configuration mentioned above includes the relationship between the uplink reference signal and the downlink reference signal, used as an index, for propagation delay estimation. The method further includes: Receive the uplink reference signal to activate the propagation delay estimation based on the index.

13. The method of claim 12, further comprising receiving an uplink reference signal to activate the propagation delay estimation.

14. The method of claim 12, wherein the estimated propagation delay is applied to synchronize the time of day.

15. The method of claim 12, further comprising: In response to at least one downlink reference signal being configured, a radio node receive and transmit timing difference measurement is performed, and the radio node is signaled to the receive and transmit timing difference measurement, or different receive and transmit timing difference measurements for the propagation delay estimate are received.

16. The method according to claim 12, The provision of the propagation delay notification configuration includes providing a propagation delay threshold; and The propagation delay notification is received in response to the current propagation delay estimate being greater than the difference between a previously provided propagation delay estimate and the propagation delay threshold.

17. The method of claim 16, further comprising: The propagation delay threshold is determined based on at least one of accuracy budget and / or mobility event statistics.

18. The method of claim 12, further comprising: Determine whether to provide the propagation delay notification configuration for the propagation delay estimation or to send the uplink reference signal configuration for the propagation delay estimation; The determination is based on at least one of time synchronization accuracy requirements, device capabilities, mobility events, or timer expiration.

19. The method of claim 12, wherein the propagation delay notification includes at least one burst request and / or expected period.

20. The method of claim 12, further comprising transmitting the propagation delay estimate.

21. The method of claim 12, further comprising estimating the propagation delay as a round-trip time (RTT).

22. The method of claim 21, wherein the RTT is a multi-RTT with measurements from neighboring cells.

23. The method of claim 12, further comprising broadcasting the propagation delay estimate.

24. The method according to claim 12, wherein: The propagation delay notification is received in response to a change in the reference signal time difference exceeding a threshold.

25. The method according to any one of claims 12 to 24, wherein the propagation delay notification is a multi-bit notification including the expected accuracy or expected period of the measurement update.

26. A communication device, comprising: At least one processor; as well as At least one non-transitory memory, including computer program code; The at least one memory and the computer program code are configured, together with the at least one processor, to cause the device to perform at least the following: Receive configuration, the configuration being used to provide propagation delay notification for propagation delay estimation, wherein the configuration includes a relationship between an uplink reference signal and a downlink reference signal used as an index for propagation delay estimation; Determine when the notification should be sent; Send the propagation delay notification; and Based on the relationship between the uplink reference signal and the downlink reference signal, the corresponding action for propagation delay estimation is determined. The device is also caused to perform: In response to the configuration of at least one downlink reference signal, the index is used to determine the at least one downlink reference signal to be used; as well as The uplink reference signal is transmitted based on at least one determined downlink reference signal to activate the propagation delay estimation.

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