Timing Advance in Cut Mode

Abstract

The wireless communication device (101) determines a timing advance for facilitating communication with each of one or more base stations (74-79, 112, 113) of the cellular network (100) based on timing measurements of one or more downlink reference signals (4145) while the wireless communication device (101) is operating in a disconnected mode, the timing advance being associated with a spatial context (80).

Description

[Technical Field]

[0001] Various examples generally relate to a wireless communication device that determines a timing advance while operating in a disconnected mode. [Background technology]

[0002] A wireless communication device (UE) connectable to a cellular network (NW) can determine its location based on uplink (UL) reference signals (RS) transmitted from the UE and received by multiple base stations (BSs), and then perform multi-angle positioning to determine the location of the UE.

[0003] Typically, the UE transmits uplink reference signals while operating in a connected mode in which a data connection between the UE and the radio access network of the cellular network is established.

[0004] 3GPP (Third Generation Partnership Project) Technical Specification 38.214, version 17.4.0, section 6.2.1 describes UL Sounding Reference Signal (SRS) transmission while the UE is operating in RRC_Connected mode.

[0005] In some applications / use cases, the location of UEs operating in a disconnected mode (such as inactive or idle mode) is required.

[0006] According to the reference implementation, the UE periodically transmits UL SRS while operating in disconnected mode. The UE is configured with time-frequency resources while operating in connected mode and before transitioning to disconnected mode, for example, with a Radio Resource Control (RRC) release message. The UE periodically transmits UL SRS using this configuration while the UE is in RRC_Inactive mode for positioning purposes. See TS38.214, Version 17.4.0 (December 2022), Section 6.2.1.4.

[0007] Such a reference implementation has been found to involve a significant increase in UE power consumption. Another limitation is that the reference implementation does not support mobility: when a UE moves to another cell in the cellular network, the UL SRS configuration of the previous cell is no longer valid. The UE needs to reacquire the UL SRS configuration of the new cell, which means that the UE has to enter connected mode. This consumes significant power.

[0008] The 3GPP Rel-18 work item on "Extended and Improved NR Positioning" has been approved in 3GPP RAN#98e. See 3GPP RP 223549. One of its objectives is to specify enhancements to realize "Low Power High Accuracy Positioning (LPHAP) Use Case 6" as defined in 3GPP TS 22.104. This includes: UL and downlink (DL) positioning, specifying enhanced SRS configuration based on SRS positioning coverage area for UEs in RRC_INACTIVE state to avoid frequent RRC connections for SRS (re)configuration; SRS for positioning configuration in multiple cells; Pre-configuration of one or more SRS for positioning configuration; SRS for positioning activation / request procedure. Specify corresponding new core requirements and identify and articulate their impact on existing specifications, including Radio Resource Management (RRM) measurements and procedures. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2023 / 275028 [Non-patent literature]

[0010] [Non-Patent Document 1] BIRENDRA GHIMIRE ET AL, "SRS Configuration for supporting LPHAP", Vol. {0} 3GPP RAN 2, No. {0} Toulouse, FR; 20221114 - 20221118, 03 November 2022(2022-11-03), 3GPP DRAFT; DISCUSSION, 3RD GENERATION PARTNERSHIP PROJECT(3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCERetrieved from the Internet: URL:https: / / www.3gpp.org / ftp / TSG_RAN / WG2_RL2 / TSGR2_120 / Docs / R2-2212072.zip R2-2212072_SRS_Configuration_Fraunhofer.docx Summary of the Invention [Problem to be solved by the invention]

[0011] There is a need for advanced techniques to enable a UE to transmit ULRS while operating in a disconnected mode.There is a need for advanced techniques to perform position location while operating in a disconnected mode. [Means for solving the problem]

[0012] This need is met by the features of the independent claims. The features of the dependent claims define respective embodiments.

[0013] A method for use in a UE is disclosed. The UE is connectable to a cellular network. The method includes determining a timing advance to facilitate communication with one or more base stations, the one or more base stations being part of the cellular network. The timing advance is determined while operating in a disconnected mode. The timing advance is determined based on timing measurements, the timing measurements being for one or more downlink reference signals, the one or more downlink reference signals being transmitted by each of the one or more base stations. The method further includes transmitting an uplink reference signal, the uplink reference signal being transmitted in response to the timing advance. The uplink reference signal is transmitted on preconfigured time-frequency resources. The uplink reference signal is transmitted upon determining that the UE is located within a predefined spatial context. The uplink reference signal is transmitted while operating in the disconnected mode.

[0014] A UE is disclosed. The UE is connectable to a cellular network. The UE comprises at least one processor and a memory. The at least one processor is configured to load program code stored in the memory. The at least one processor is configured to execute the program code. Upon loading and executing the program code, the at least one processor is configured to determine a timing advance to facilitate communication with one or more base stations, the one or more base stations being part of the cellular network. The timing advance is determined while operating in a disconnected mode. The timing advance is determined based on timing measurements. The timing measurements are for one or more downlink reference signals. The at least one processor is further configured to transmit an uplink reference signal. The uplink reference signal is transmitted in response to the timing advance. The uplink reference signal is transmitted on pre-configured time-frequency resources. The uplink reference signal is transmitted upon determining that the UE is located within a pre-defined spatial context. The uplink reference signal is transmitted while operating in the disconnected mode.

[0015] A method for use in a node of a cellular network is disclosed. The method includes providing at least one configuration message to a UE, the at least one configuration message associated with the UE determining a timing advance for transmission of an uplink reference signal based on timing measurements based on a downlink reference signal, the downlink reference signal being transmitted by one or more base stations of the cellular network. The method also includes triggering the one or more base stations to monitor the uplink reference signal transmitted by the UE while operating in a disconnected mode.

[0016] The node may be a base station of the cellular network. Alternatively or additionally, the node may be a positioning server of the cellular network.

[0017] A node of a cellular network is disclosed, the node comprising at least one processor and a memory. The at least one processor is configured to load program code from the memory and execute the program code. Upon loading and executing the program code, the at least one processor is configured to provide at least one configuration message to a UE. The at least one configuration message is associated with the UE determining a timing advance for transmission of an uplink reference signal based on timing measurements based on a downlink reference signal. The downlink reference signal is transmitted by one or more base stations of the cellular network. The at least one processor is further configured to trigger the one or more base stations to monitor the uplink reference signal transmitted by the UE while operating in a disconnected mode.

[0018] A method for use in a positioning server of a cellular network is disclosed, the method including obtaining an indication from one or more base stations of the cellular network indicating that the one or more base stations support the UE operating in a disconnected mode to transmit uplink reference signals according to a timing advance, the timing advance being determined by the UE, and configuring the UE to transmit the uplink reference signals while operating in the disconnected mode.

[0019] A positioning server for a cellular network is disclosed. The positioning server comprises at least one processor and a memory. The at least one processor is configured to load program code from the memory and execute the program code. Upon loading and executing the program code, the at least one processor is configured to obtain an indication from one or more base stations of the cellular network indicating that the one or more base stations support the UE operating in a disconnected mode to transmit uplink reference signals according to a timing advance, the timing advance being determined by the UE. The method also includes configuring the UE to transmit the uplink reference signals while operating in the disconnected mode.

[0020] A computer program is disclosed that includes program code that is loaded and executed by at least one processor, the at least one processor, when executing the program code, performing the method disclosed above.

[0021] It is to be understood that the features mentioned above and those described below may be used not only in the respective combinations shown, but also in other combinations or alone without departing from the scope of the disclosure. [Brief explanation of the drawings]

[0022] [Figure 1] 1 illustrates a schematic diagram of a cellular network, according to various examples; [Figure 2] 1 illustrates a schematic diagram of a UE according to various examples. [Figure 3A] 1 illustrates a schematic diagram of a base station, according to various examples. [Figure 3B] 1 illustrates a schematic diagram of a location server, according to various examples; [Figure 4] 1 is a flowchart of a method for use in a UE, in accordance with various examples. [Figure 5] 1 is a flowchart for use in a base station, in accordance with various examples. [Figure 6]1 is a flowchart for use with a positioning server, according to various examples. [Figure 7] 1 illustrates a schematic representation of the spatial context of various examples. [Figure 8] FIG. 1 is a signaling diagram according to various examples. [Figure 9] FIG. 1 is a signaling diagram according to various examples. [Figure 10] FIG. 1 is a signaling diagram according to various examples. DETAILED DESCRIPTION OF THE INVENTION

[0023] Some examples of the present disclosure generally provide multiple circuits or other electrical devices. All references to circuits and other electrical devices and the functions each provides are not limited to those shown and described herein. While particular labels may be assigned to various disclosed circuits or other electrical devices, such labels do not limit the operational scope of the circuits and other electrical devices. Such circuits and other electrical devices can be combined and / or separated depending on the type of electrical implementation desired. The circuits and / or other electrical devices disclosed herein can include any number of microcontrollers, graphics processor units (GPUs), integrated circuits, memory devices (e.g., flash memory, random access memory (RAM), read-only memory (ROM), electrically programmable read-only memory (EEPROM), or other suitable variations thereof), and software that cooperate with each other to perform the operations disclosed herein. Furthermore, any one or more of the electrical devices can be configured to execute program code recorded on a non-transitory computer-readable medium and programmed to perform any number of the functions disclosed herein.

[0024] Examples of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the description of the following examples is not intended to be understood in a limiting sense. The scope of the present disclosure is not limited by the examples or drawings described below, and the drawings are merely illustrative.

[0025] The drawings are schematic representations, and elements shown in the drawings are not necessarily drawn to scale. Rather, the various elements are represented so that their function and general purpose will be apparent to one skilled in the art. Connections or couplings between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be achieved by indirect connections or couplings. Couplings between components may also be achieved by wireless connections. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

[0026] Aspects are disclosed relating to the operation of a UE connectable to a cellular network, particularly when operating the UE in a disconnected mode.

[0027] Disconnected mode can be RRC_Inactive or RRC_Idle mode according to 3GPP TS 38.331, version 17.2.0, section 4.2.1. While the UE is operating in disconnected mode, the data connection between the cellular network and the UE is not maintained. Disconnected mode differs from connected mode, in which the data connection between the UE and the cellular network is maintained.

[0028] According to the techniques disclosed herein, a UE transmits an uplink reference signal (ULRS) while operating in a disconnected mode. The uplink reference signal may be an SRS, particularly an SRS for positioning. By allowing transmission of the uplink reference signal while operating in a disconnected mode, frequent switching from a disconnected mode to a connected mode can often be avoided, thereby reducing the power consumption of the UE.

[0029] According to the technology disclosed herein, a UE transmits uplink reference signals while operating in a disconnected mode. The UE is permitted to transmit uplink reference signals taking into account the UE's mobility. This contrasts with prior art implementations in which the UE is permitted to transmit uplink reference signals only when the UE has zero movement, i.e., while the UE is stationary. According to various examples, the amount of UE movement is restricted. For this purpose, specific procedures are linked to and restricted by specific spatial contexts. As long as the UE is within a spatial context, the UE is permitted to transmit uplink reference signals. The uplink reference signals are transmitted on preconfigured time-frequency resources allocated for UE positioning. In other words, the UE's location can be determined based on the uplink reference signals. One or more base stations of a cellular network can receive the uplink reference signals and perform location measurements. Based on these location measurements, the UE is located, for example, by a positioning server of the cellular network.

[0030] In the following, various examples are described in the context of using the ULRS transmitted by the UE for positioning while operating in disconnected mode, although the ULRS can also be transmitted for purposes other than positioning, such as channel sounding.

[0031] The transmission of the uplink reference signal is synchronized with the timing reference of the cellular network. A base station in a cellular network is expected to receive signals transmitted from one or more UEs at different locations within the cell according to this timing reference. To achieve this, the UE compensates for the radio propagation delay of the signal. A time offset called a timing advance (TA) is applied. UEs located farther from a base station must transmit their signals earlier than UEs located closer to the base station so that the signals arrive at the base station at the same time. This results in UEs located farther away applying a larger TA (i.e., the UE uses a larger timing compensation value), while UEs closer to the base station apply a relatively smaller TA (i.e., the UE uses a smaller timing compensation value). The TA controls the uplink (UL) transmission timing of each UE. The TA helps ensure that UL transmissions from the UE are synchronized when received at the base station. For a UE located at a fixed location within the coverage area of ​​a cellular network, each base station is associated with its own TA (due to the different distances to each base station).

[0032] According to the reference implementation, the TA is obtained during the random access (RACH) procedure as described in 3GPP TS 38.321, version 17.2.0, section 5.2. According to the reference implementation, the UE transmits a RACH preamble, the base station calculates the TA, and the base station then provides the TA to the UE via a response message. According to the reference implementation, the UE will use the TA for subsequent transmissions. According to the reference implementation, if the UE is configured for UL SRS transmission in RRC_Inactive mode, the UE will use the TA value obtained in connected mode when transmitting UL SRS in RRC_Inactive mode. That is, the TA value is relative to the serving cell from which the UE was released.

[0033] Various techniques are based on the discovery that performing a RACH procedure to obtain a TA consumes power at the UE. According to various examples, relatively low power consumption is achieved by determining the TA and obtaining a UL SRS configuration from a base station(s), including UL SRS time-frequency resources and spatial directions (i.e., beam directions).

[0034] According to various examples, the UE transmits the UL SRS based on the TA calculated by the UE. According to various examples, the UE transmits the UL SRS on a pre-configured UL time-frequency resource according to the TA. The UE does not need to transition to a connected mode to determine the TA, thereby reducing UE power consumption.

[0035] According to some examples, the use of a locally determined TA is limited to a particular spatial context. According to some examples, the TA is thereby related to the spatial context. According to some examples, determining the TA at a UE based on timing measurements performed by the UE based on downlink reference signals received by the UE while the UE is operating in a disconnected mode is limited to a particular spatial context. The spatial context defines a geographical region or area within which the UE is permitted to determine the TA as described above. Limiting the determination of the TA at the UE to a spatial context can prevent the UE from generally interfering with communications in the cellular network outside the spatial region. In particular, the UE may miscalculate the TA, and such miscalculation may result in interference with other communications in the cellular network.

[0036] Figure 1 illustrates a schematic diagram of a cellular network 100. The example of Figure 1 illustrates a cellular network 100 based on the 3GPP 5G architecture, details of which are described in 3GPP TS 23.501, version 17.0.0 (March 30, 2021).

[0037] 1, a UE 101 may be connected to a cellular network 100. For example, the UE 101 may be one of a mobile phone, a smartphone, an IoT device, etc.

[0038] The UE 101 can connect to the NW 100 via the RAN 111. The RAN 111 typically comprises one or more base stations 112 and 113. The base stations 112 and 113 are also referred to as "gNBs" in 3GPP NR. A radio link 114 is shown between the RAN 111 and the UE 101.

[0039] The RAN 111 is connected to a Core Network (CN) 115. The CN 115 includes a User Plane (UP) 191 and a Control Plane (CP) 192. Application data is typically routed via the UP 191. For this purpose, a UP Function (UPF) 121 is provided. The UPF 121 may implement a router function. Application data may pass through one or more UPFs 121. In the scenario of FIG. 1, the UPF 121 acts as a gateway to a Data Network (DN) 180, such as the Internet or a local area network. Application data may be exchanged between the UE 101 and one or more servers on the DN 180.

[0040] The CN 115 of the cellular network 100 also includes an Access and Mobility Management Function (AMF) 131, a Session Management Function (SMF) 132, a Policy Control Function (PCF) 133, an Application Function (AF) 134, a Network Slice Selection Function (NSSF) 135, an Authentication Server Function (AUSF) 136, a Unified Data Management (UDM) 137, and a Location Management Function (LMF) 199, which implements a location control node. Protocol reference points N1-N22 between these nodes are also shown in Figure 1.

[0041] A data connection 189 is established between the UE 101 and the user plane 191 of the CN 115 via the RAN 111 towards the DN 180. For example, a connection can be established to the Internet or another packet data network. To establish the data connection 189, each UE 101 can perform a RACH procedure. The data connection 189 can include one or more bearers, such as a dedicated bearer or a default bearer. Application data can be transmitted over the data connection 189. When the data connection 189 is not established or in use between the UE 101 and the RAN 111, the UE 101 operates in a disconnected mode. Examples include RRC_Inactive and RRC_Idle.

[0042] The positioning server implemented by the LMF 199 processes the location information of the UE 101. This may include forwarding forwarding assistance data to the target UE 101 to locate it and assist in UE-based and / or UE-assisted positioning, and / or may include target UE positioning. See 3GPP TS 38.305 V17.2.0 (December 2022), Section 5.1.

[0043] 2 illustrates a schematic diagram of details regarding the UE 101. The UE 101 includes a processor 1011 and a memory 1012. Program code is stored in the memory 1012. The processor 1011 is capable of loading and executing the program code. After loading and executing the program code, the processor performs the techniques disclosed herein, such as communicating with, for example, base stations 112 and 113 over wireless links 114 via a communication interface 1013; receiving messages from the cellular network 100, for example, from the LMF 199; transitioning between connected and disconnected modes of operation; performing RACH procedures, for example, until at least partially obtaining a TA; determining a TA for each of a plurality of base stations; and transmitting uplink reference signals based on the TA while operating in disconnected mode.

[0044] FIG. 3A schematically illustrates details regarding the base station 112. While FIG. 3A illustrates the base station 112, the base station 112 may have a similar configuration. The base station 112 includes a processor 1121 and a memory 1122. Program code is stored in the memory 1122. The processor 1121 may load and execute the program code. After loading and executing the program code, the processor 1121 performs the techniques disclosed herein. For example, the processor 1121 may communicate with, for example, the UE 101 over the wireless link 114 via the communication interface 1123, communicate with other nodes of the cellular network via the communication interface 1123, obtain messages from other nodes of the cellular network, for example, from the LMF 199, provide messages to other nodes of the cellular network, for example, the LMF 199, provide messages to or obtain messages from the UE 101, transmit downlink reference signals, and monitor uplink reference signals transmitted by the UE 101 while operating in a disconnected mode.

[0045] 3B schematically illustrates details regarding the LMF 199. The LMF 199 includes a processor 1991 and a memory 1992. Program code is stored in the memory 1992. The processor 1991 is capable of loading and executing the program code. Upon loading and executing the program code, the processor 1991 performs the techniques disclosed herein. For example, the LMF 199 communicates with other nodes of the cellular network (e.g., base stations 112, 113) or the UE 101 via a communication interface 1993, determines the position / location of the UE 101 based on positioning reports obtained from multiple base stations, and provides a configuration for transmitting an uplink reference signal to the UE.

[0046] 4 is a flowchart of a method according to various examples. The method of FIG. 4 is used in a UE. The UE is connectable to a cellular network. For example, the method of FIG. 4 can be used by the UE 101. More specifically, the method of FIG. 4 can be performed by a processor 1011 based on program code stored in the memory 1012 and read and executed by the processor 1011.

[0047] Each option box is indicated by a dashed line.

[0048] In optional box 3005, the UE may provide an indication to the cellular network that the TA can be determined based on timing measurements of one or more downlink reference signals transmitted by one or more base stations of the cellular network.

[0049] While operating in connected mode, the UE may provide RRC control messages indicating its capabilities.

[0050] In optional box 3010, the UE optionally obtains a reference TA from the cellular network.

[0051] For example, a serving base station of a cellular network can provide an indication of a reference TA while the UE is operating in connected mode. This reference TA can be included in an RRC disconnect message that triggers the UE to transition from connected mode to disconnected mode. The reference TA can be obtained as part of a configuration message related to the determination of a local TA at the UE.

[0052] Instead of or in addition to obtaining a reference TA in box 3010, it is also possible to indicate a tolerance range for the TA determined by the UE. Such tolerance range may specify an upper and / or lower limit for the TA. Instead of or in addition to obtaining a reference TA or tolerance range, it is possible to obtain candidate values ​​for the TA. For example, an array of candidate values ​​may be obtained. The candidate values ​​may be indicated by a reference and a step size.

[0053] Instead of or in addition to obtaining a reference TA in box 3010, a reference TA can be obtained. The reference TA is obtained using conventional methods, such as when the UE obtains a TA during a registration process (e.g., after the UE powers up). The reference TA can be obtained when the UE is operating in connected mode.

[0054] Such information regarding constraints and / or references for determining the TA at the UE is guidance provided by the cellular network to the UE to facilitate the TA determination at the UE.

[0055] Such information may be provided for each of multiple base stations in a particular spatial context in which the UE is permitted to determine the TA based on timing measurements performed at the UE.

[0056] In FIG. 4, box 3010 is separated from box 3015, but the reference TA and / or candidate values ​​for the TA and / or acceptable ranges for the TA may also be obtained as part of at least one configuration message obtained in box 3015.

[0057] In box 3015, at least one configuration message is optionally obtained. The at least one configuration message is related to determining a TA in the UE. The at least one configuration message in box 3015 may be provided by a RAN of the cellular network. For example, a base station of a radio access network of the cellular network may generate and provide the at least one configuration message.

[0058] In some examples, a single configuration message is obtained. The single configuration message may include one or more of the following example parameters: As yet another example, multiple configuration messages may be obtained, for example, at different times. Furthermore, it is possible that at least one of the multiple configuration messages is obtained by the UE while operating in a connected mode and at least one other of the multiple configuration messages is obtained by the UE while operating in a disconnected mode (FIG. 4 shows an example of the UE transitioning to the disconnected mode at box 3020).

[0059] The at least one configuration message in box 3015 may indicate a spatial context. In other words, the spatial context is related to a geographical region. Only if the UE is located within the spatial context can the UE determine the TA based on the timing measurements.

[0060] There are various options available for defining the spatial context. As an example, the spatial context can be defined such that the UE needs to be located in one or more cells of a cellular network. Thus, the at least one configuration message obtained in box 3015 may include a list of cell identities.

[0061] As an example, alternatively or additionally, the spatial context may be defined by the UE being located within a geographical region defined by a geofenced area. The geofenced area may include, for example, a number of nodes at a particular latitude and longitude, which define a polygonal outline of the geofenced area. At least one configuration message may indicate the geofenced area.

[0062] As an example, alternatively or additionally, the predefined spatial context may be defined by the UE being able to receive downlink reference signals transmitted by the cellular network. The reference signals may have a specific ID. The reference signals may include such ID. The reference signals may also be identified by specific time-frequency resources transmitted. An example is a synchronization signal block (SSB) transmitted by a base station of the cellular network. The at least one configuration message may indicate a DL RS.

[0063] According to some examples, the UE performs measurements on downlink reference signals. For example, received signal strength may be measured. One or more reception characteristics (e.g., received signal strength) may then be compared to one or more pre-configured thresholds. Any detected downlink reference signals that pass the threshold comparison are deemed to have been received by the UE and, therefore, are considered in determining whether the UE is located within a pre-defined spatial context.

[0064] Various options for defining such spatial context can be combined to form further scenarios.

[0065] In general, the cellular network communicates whether the UE is permitted to self-calculate the TA and, if so, whether to use PRS or SSB. Specifically, the at least one configuration message obtained in box 3015 indicates, in some examples, whether the UE is permitted to use a TA determined based on timing measurements based on downlink reference signals. In other words, the at least one configuration message can activate the UE to use a locally calculated TA for transmitting uplink reference signals.

[0066] The at least one configuration message obtained in box 3015, in some examples, indicates a calculation rule for determining a TA based on timing measurements based on downlink reference signals. The calculation rule may specify the number of timing measurements to be performed. The calculation rule may specify a time offset between consecutive timing measurements. The calculation rule may specify, for example, the reference TA obtained in box 3010 and / or candidate values ​​for the TA and / or a method for considering a tolerance range for the TA.

[0067] The at least one configuration message obtained in box 3015 may, in some examples, indicate one or more downlink reference signal types, which may specify a particular downlink reference signal to use, such as whether to use SSB or a channel state information reference signal (CSI RS). The at least one configuration message obtained in box 3015 may indicate time-frequency resources of DL RSs that the UE uses to determine TA.

[0068] At least one configuration message associated with transmitting an uplink reference signal is obtained in box 3016. This is generally optional. In other scenarios, the UE may be pre-configured with this. In such scenarios, this configuration is already available to the UE.

[0069] As some examples, the at least one configuration message is obtained from a positioning server, such as the LMF 199. The serving base station and / or each neighboring base station can provide information regarding the transmission of the ULRS to the positioning server, which can then provide the at least one configuration message to the UE.

[0070] The at least one configuration message in box 3016 is provided by a positioning server of a cellular network. If multiple configuration messages are obtained in box 3016, at least one of the multiple configuration messages can be provided by the positioning server. The at least one configuration message in box 3016 can be provided in part by a radio access network of the cellular network. If multiple configuration messages are obtained in box 3016, at least one of the multiple configuration messages can be provided by the radio access network.

[0071] In the scenario of FIG. 4, at least one configuration message is provided before transitioning to disconnected mode (i.e., before box 3020), but at least one configuration message may also be provided after transitioning to disconnected mode (i.e., after box 3020).

[0072] The pre-configured characteristics of the UL RS may include specific parameters such as the association of SRS resources with SSB resources. A dedicated UL SRS can be configured for use by a UE. Other UEs may not be able to use these SRS resources.

[0073] The configuration message can select a configuration parameter set from multiple candidate sets pre-configured in the UE. The configuration message can include a pointer to the selected configuration parameter set.

[0074] The at least one configuration message obtained in box 3016 may indicate pre-configured time-frequency resources. The pre-configured time-frequency resources may be explicitly specified or implicitly specified. For example, scheduling information may be provided.

[0075] The at least one configuration message obtained in box 3016 may indicate a frequency start position of the pre-configured time-frequency resources for transmitting the uplink reference signal. The frequency start position may be indicated as a lower limit of a band. The frequency start position may be indicated as a lower limit of one or more subcarriers.

[0076] The at least one configuration message obtained in box 3016 may indicate a bandwidth of the pre-configured time-frequency resources. The bandwidth may be indicated by a number of subcarriers. The bandwidth may be indicated by a specific bandwidth portion.

[0077] The at least one configuration message obtained in box 3016 may indicate a frequency stop of the pre-configured time-frequency resources. The frequency stop may be indicated as an upper limit of a band. The frequency stop may be indicated as an upper limit of one or more subcarriers.

[0078] The at least one configuration message obtained in box 3016 may indicate the numerology of the pre-configured time-frequency resources (see, for example, 3GPP TS 38.211, version 17.2.0, table 4.21), which indicates the subcarrier spacing.

[0079] The at least one configuration message obtained in box 3016 may indicate a number of pre-configured time-frequency resource repetitions, for example, each repetition may include one or more time-frequency resources in a particular time slot.

[0080] The at least one configuration message obtained in box 3016 may indicate a repetition rate of the pre-configured time-frequency resources. The time-frequency resources are repeatable, i.e., they recur every time. The repetition rate specifies how often they recur. For example, every nth subframe or time slot may include such a resource.

[0081] The at least one configuration message obtained in box 3016 may indicate a comb size of the pre-configured time-frequency resources. The comb size may specify a frequency offset of the frequency pattern of the time-frequency resources.

[0082] The at least one configuration message obtained in box 3016 may indicate an association of the pre-configured time-frequency resource with the further time-frequency resource on which the downlink reference signal is transmitted, e.g., the time-frequency resource may be defined relative to the further time-frequency resource by, e.g., a time offset and / or a frequency offset.

[0083] The at least one configuration message obtained in box 3016 may indicate signal characteristics of the uplink reference signal. For example, it may specify an ID to be used for the uplink reference signal, a particular scrambling code, or a sequence design.

[0084] The at least one configuration message obtained in box 3016 may indicate a spatial relationship of the uplink reference signals. For example, a particular beam may be indicated. Beamforming parameters for transmission of the uplink reference signals may be indicated.

[0085] In the first example, the UE is pre-configured with a specific spatial direction for transmitting UL RS, such as the base station's SRS reception behavior. In this case, there may be an association between SSB resources and UL SRS resources. This association may be different for each base station from which the UE transmits UL RS. Here, the UE performs conventional SSB measurements for multiple cells. Once the UE identifies the optimal spatial direction for the received SSB, the UE is expected to use the same beam for UL RS transmission.

[0086] In the second example, the UE also performs SSB measurements, but only to the serving cell, and therefore the association of SSB with ULRS resources is limited to that serving cell.

[0087] In the third example, the UE is not provided with spatial direction information. Here, the UE only knows the resources for transmitting the SRS. It is up to the UE to decide whether to use spatial direction for UL SRS transmission.

[0088] The UE may be configured by indicating the time / frequency resources of the UL SRS, SRS signal characteristics such as UL sequence ID, spatial relationship of the UL SRS, and / or TA parameters (step size, max value).

[0089] The above discloses various parameters and information elements that may be indicated in the at least one configuration message obtained in box 3016 .

[0090] There may be common ULRS configurations and cell-specific ULRS configurations used by each base station. Common parameters mean that multiple base stations share the same parameters. For example, common parameters may be RS frequency start, RS bandwidth, RS numerology (carrier spacing), repetition rate, comb size, etc. Cell-specific parameters are not shared between different base stations.

[0091] According to some examples, the at least one configuration message associated with the transmission of the uplink reference signal indicates one or more shared parameters jointly configured for transmitting the uplink reference signal toward different base stations among a plurality of base stations of the cellular network. In other words, for example, certain characteristics of time-frequency resources may be shared among a plurality of base stations of the cellular network. In such a case, the at least one configuration message obtained in box 3016 may include an information element indicating the sharing of such information. In this case, the at least one configuration message does not include duplication of such information for different base stations.

[0092] The at least one configuration message obtained in box 3016 may indicate one or more cell-specific parameters individually configured for transmitting uplink reference signals to different base stations among multiple base stations of the cellular network. For example, different cells may use different time-frequency resources, and the UE may be configured to transmit uplink reference signals to different base stations at different times. The cell-specific parameters may include, for example, an association between SRS resources and SSB resources.

[0093] The above discloses a scenario in which the at least one configuration message obtained in box 3016 indicates one or more parameter values. These parameter values ​​may be explicitly indicated, e.g., as numerical values, in respective fields of the at least one configuration message. It is also possible to indicate such parameter values ​​implicitly. For example, a pointer to pre-configured parameter values ​​(e.g., pre-configured by a positioning server) may be provided, e.g., by a base station or a group of base stations. The UE may have multiple ULRS configuration sets, e.g., provided by a positioning server. The base station (e.g., a serving base station) may inform the UE of the selected configuration when the base station triggers the transmission of an UL SRS to the UE. Thus, as an example, the positioning server pre-provisions multiple candidate configurations, and the base station selects an actual configuration from these candidate configurations.

[0094] The UE transitions to a disconnected mode in box 3020, which means that the data connection is released, interrupted, or suspended. In the disconnected mode, the UE does not maintain an active data connection to the cellular network. For example, the connected mode is RRC_Connected, and the disconnected mode can be, for example, RRC_Inactive or RRC_Idle.

[0095] In some scenarios, the disconnect message obtained as part of box 3020 may also include the information described with respect to box 3015. In other words, the configuration message of box 3015 may be implemented at least in part by a disconnect message that triggers a transition from connected mode to disconnected mode.

[0096] In box 3025, the UE optionally obtains a request to transmit an uplink reference signal.

[0097] For example, the request may be obtained or triggered from a positioning server of the cellular network, such as the LMF 199. In other words, the request triggers the UE to participate in a positioning procedure. In some examples, the request is obtained after transitioning to disconnected mode in box 3020. In other examples, the request is obtained before transitioning to disconnected mode. In such a scenario, box 3025 is executed before box 3020.

[0098] In box 3030, the UE determines one or more TAs based on timing measurements based on one or more downlink reference signals transmitted by the cellular network. In some examples, the UE makes timing measurements from multiple cells and determines a TA that matches the UL timing of all of these cells.

[0099] Box 3030 includes receiving one or more downlink reference signals in box 3031. The one or more downlink reference signals may be SSBs or positioning reference signals (PRS).

[0100] One or more downlink reference signals may be transmitted by a cellular network. They may be broadcast.

[0101] Box 3030 further includes a step of calculating (box 3032) a propagation time of the one or more downlink reference signals received in box 3031. Then, a TA is determined based on the calculated propagation time. The TA is determined to compensate for the delay caused by the propagation time.

[0102] A validity check may be performed on the TA determined in box 3032. Box 3033 includes comparing the TA calculated in box 3032 with at least one of an acceptable range of TA, a reference TA, and a candidate value for TA. Such information may be obtained as part of box 3010 or as part of box 3015, as described above. The TA previously determined in box 3032 may then be discarded or kept depending on the comparison. For example, it may be checked whether the TA calculated in box 3032 is within an acceptable range. If so, the determined TA is used for further purposes. If not, the determined TA is discarded. If candidate values ​​for TA are available, the candidate value closest to the determined TA may be selected and used as the TA to be used subsequently.

[0103] The validity check of the TA determined by the UE may fail. In other words, when a specific TA is calculated for one of one or more base stations, the corresponding TA does not satisfy one or more validity criteria. For example, the determined TA may be outside a predefined range. In such a scenario, various options are possible. If the validity check fails, the UE can use the TA most recently provided by the network for each base station. In other words, it can fall back to a preconfigured TA obtained from the cellular network. Alternatively, the UE can perform a RACH procedure to obtain an updated TA. The UE may not need to complete a random access procedure, but it must complete the random access procedure when obtaining an updated TA. This is also described in box 3034.

[0104] In a further scenario, in box 3034, the UE performs a random access procedure to obtain a reference TA from the cellular network. The UE can then adjust this reference TA based on timing measurements performed based on the reference signal obtained in box 3031.

[0105] In box 3035, a transmit beam for the uplink reference signal is determined. The transmit beam is determined based on one or more downlink reference signals. For example, multiple elements may receive downlink reference signal bursts associated with different transmit beams at the base station. Then, based on general reciprocity, a transmit beam at the UE may be selected according to the directionality of the downlink reference signal.

[0106] In box 3045, the UE determines whether it is located within a predefined spatial context. Depending on the definition of the spatial context, different checks are performed in box 3045. For example, the UE can monitor whether it is receiving a specific reference signal from a cellular network. The UE may determine whether its latitude and longitude location is within a geofenced area. The UE determines whether it can receive information conveyed from a specific cell included in a list of cell IDs.

[0107] If the UE determines that it is located within the predefined spatial context, it transmits an uplink reference signal in box 3050 according to the TA determined in box 3030. If the UE determines that it is not located within the spatial context, it executes a fallback option in box 3055. As an example, the fallback option includes transmitting an uplink reference signal using the TA obtained in box 3010 as reference.

[0108] As can be seen from FIG. 4, the UE calculates the TA based on reference signals received from at least one cell (e.g., the serving cell and / or another cell) in box 3030. The UE performs timing measurements in box 3050 and uses the measurement results for the TA of the UL transmission. Therefore, the UE does not need to perform a random access procedure to determine the TA in box 3030. The UE can determine the TA while operating in disconnected mode. The UE can perform a RACH procedure in box 3034. The RACH procedure is aborted upon receiving message 2. In this case, the self-calculated TA is used to adjust the TA value obtained by the conventional method.

[0109] 5 is a flowchart of a method according to various examples. The method of FIG. 5 is used in a base station of a cellular network. The base station can be connected to a UE. For example, the method of FIG. 5 can be used in base station 112 or base station 113. More specifically, the method of FIG. 5 can be performed by a processor 1121 reading and executing program code stored in memory 1122.

[0110] Each option box is indicated by a dashed line.

[0111] In optional box 3105, the base station may obtain from the UE an indication indicating that the UE is capable of determining the TA based on timing measurements of one or more downlink reference signals transmitted by the radio access network of the cellular network. Box 3105 corresponds to box 3005, and details of such capability information message have already been described in box 3005.

[0112] In optional box 3110, the base station provides the UE with a reference TA. Box 3110 corresponds to box 3010, and details of which have already been described therein.

[0113] In optional box 3115, the base station determines one or more parameters associated with the UE that determine the TA for transmission of the uplink reference signal based on timing measurements of the downlink reference signal transmitted by the radio access network of the cellular network.

[0114] The base station may determine, in box 3115, a spatial context based on the timing measurements that the UE may use to determine the TA. This is shown in box 3116.

[0115] For example, in box 3116, the spatial context can be determined based on an application registered in association with the UE. This can be a positioning application. For example, the application can relate to asset tracking or IoT device monitoring. The application can relate to positioning in a factory environment. In other words, the application can set specific geographic constraints regarding an area where UE positioning is required. The spatial context can then be determined to cover that area. The spatial context can be determined to not exceed such required geographic constraints to minimize interference.

[0116] The spatial context may also be predefined.

[0117] Alternatively or additionally, the base station determines an acceptable range of TA in box 3117. This determination can be made based on the range of the spatial context. In particular, the base station can leverage prior knowledge about the base station's positioning within the geographic region defined by the spatial context. This limits the maximum TA that a UE moving within the constraints imposed by the spatial context can observe. The acceptable range can be set accordingly.

[0118] The tolerance range may also be predefined.

[0119] Alternatively or additionally, in box 3118, the base station determines whether the UE is permitted to determine TA based on timing measurements based on received downlink reference signals while operating in disconnected mode. In other words, the base station can determine whether to enable or disable such local TA calculation in the UE.

[0120] Various options are available for determining whether to enable or disable the local determination of TA at the UE. In particular, the base station can consider, for example, whether the UE is capable of doing so, as indicated in box 3105. Alternatively or additionally, the base station can consider applications associated with and registered with the UE that require positioning of the UE. For example, such applications may impose specific positioning latency and / or power constraints on power consumption at the UE. Depending on whether such constraints require low-power, low-latency positioning of the UE, the base station may enable or disable the local determination of TA at the UE. This limits local TA calculations to scenarios that are essential from an application perspective, limiting interference risks.

[0121] In box 3119, the base station, while operating in disconnected mode, optionally determines a calculation rule for determining the TA based on timing measurements based on downlink reference signals received by the UE. Details of each possible calculation rule have already been described in box 3015 of Figure 4. For example, this calculation may be determined according to the capability information indicated by the UE in box 3105.

[0122] Additionally, various parameters that may be indicated to the UE as part of the configuration message for determining the TA in box 3015 are described in connection with Figure 4. All of these parameters and further parameters may be determined by the base station in box 3115.

[0123] In box 3120, the base station provides the UE with a configuration message or messages indicating one or more parameters determined in box 3115. In some scenarios, the base station can report these parameters, at least in part, to a positioning server (e.g., LMF 199) of the cellular network. The positioning server can forward these parameters to the UE.

[0124] Box 3120 corresponds to box 3015 in FIG.

[0125] In box 3121, the base station determines a configuration for the UE to transmit reference signals. Various parameters of such a configuration have already been described in box 3016. The base station may determine time-frequency resources for transmission of uplink reference signals. The base station may then provide such a configuration to the UE, for example via an LMF. This is described in box 3122.

[0126] In general, the UE and the base station may explicitly or implicitly inform the positioning server that they support positioning in UE disconnected mode in box 3122. In other words, the base station (and optionally further base stations in the spatial context) may send an indication to the positioning server of the cellular network that they support the UE operating in disconnected mode to transmit uplink reference signals according to a TA determined locally at the UE.

[0127] In box 3125, the UE transitions to a disconnected mode, which includes providing the UE with a disconnect message. Box 3125 corresponds to box 3020 and has already been described in detail.

[0128] A request to transmit an uplink reference signal to the UE may optionally be provided in box 3130. More details in this regard have already been provided in box 3025.

[0129] The base station then receives the uplink reference signal transmitted from the UE in box 3140, according to the configuration determined in box 3120.

[0130] In box 3145, the base station performs position measurements, which may include, for example, measuring time difference of arrival and / or angle of arrival.

[0131] Such position measurements may be reported to the LMF in box 3150 .

[0132] FIG. 6 is a flowchart of a method according to various examples. The method of FIG. 6 is used in a positioning server of a cellular network. The cellular network includes a wireless access network including multiple base stations. A UE can connect to the cellular network through the wireless access network. For example, the method of FIG. 6 can be used in the LMF 199. For example, the method of FIG. 6 can be executed by loading and executing program code stored in a memory 1992 into a processor 1991.

[0133] Each option box is indicated by a dashed line.

[0134] In box 3505, the location server obtains an indication that one or more base stations of the wireless access network of the cellular network support the UE operating in a disconnected mode to transmit an uplink reference signal according to a time interval determined by the UE based on timing measurements performed by the UE based on the downlink reference signal. The DL RS is transmitted while the UE is operating in the disconnected mode. Box 3505 corresponds to box 3122.

[0135] The location server optionally obtains configurations for transmitting uplink reference signals for each of a plurality of base stations, at box 3505. Certain parameters may be shared among multiple base stations.

[0136] For example, the time-frequency resources used by the UE to transmit uplink reference signals may be indicated, the numerology may be indicated, and the recurrence rate of the time-frequency resources that recur over time may be indicated.

[0137] The location server then configures the UE to transmit uplink reference signals while the UE is operating in disconnected mode in box 3510. This includes providing the UE with the uplink reference signal transmission configuration obtained in box 3505.

[0138] In optional box 3511, the location server can request positioning of the UE. In particular, the location server can provide a command to the radio access network of the cellular network to reach the UE to start transmitting uplink reference signals for the UE to perform positioning. This can be done while the UE is operating in idle mode. The request can then be sent to the UE using a paging or wake-up procedure. See also box 3025.

[0139] The request in box 3511 is provided as needed to determine the location of the UE. For example, an application associated with the UE (such as an asset tracking application) may request that the location server provide an update on the location of the UE.

[0140] In box 3515, the positioning server obtains one or more positioning reports from one or more base stations. These one or more positioning reports are based on the one or more base stations receiving the uplink reference signals from the UE when performing positioning based on the uplink reference signals received from the UE. Box 3515 corresponds to box 3145.

[0141] The positioning server can then determine the location of the UE based on the position positioning report obtained in box 3515.

[0142] Figure 7 shows various example deployment scenarios. Figure 7 shows a use case of Low Power High Accuracy Positioning (LPHAP) in a factory, for example. High accuracy positioning is likely to become important in factories in the future. See, for example, 3GPP TS 22.104, version 17.7.0, section 5.1.

[0143] A UE 71 supporting LPHAP (LpUE 71) requires significantly lower power consumption compared to a conventional UE for 3GPP NR. However, there may be some limitations. One potential use case for the LpUE is operating in a factory / warehouse with a certain number of base stations 74-79, as shown in FIG. 7. The location of the LpUE 71 needs to be tracked for specific purposes, such as factory automation, tracking, and logistics. The LpUE 71 is expected to have mobility capabilities within the factory / warehouse and therefore interacts with base stations 74 and 76. This is shown in FIG. 7. Here, the LpUE 71 supports mobility in combination with a limited number of base stations 74-79. When the LpUE 71 leaves the factory, the LpUE 71 may lose its low power consumption capabilities or may not operate at all.

[0144] This defines a spatial context 80. The spatial context 80 covers an indoor factory floor. The spatial context 80 corresponds to a geographical region. Each spatial context 80 is indicated by a dotted line in Figure 7.

[0145] Various options are available for defining the spatial context 80. For example, the spatial context 80 can be defined by a geofence area. Alternatively or additionally, the spatial context 80 can be defined by the coverage area of ​​all base stations 74-79. The respective cell ID lists can also be used to define the spatial context 80.

[0146] Within the spatial context 80, the UE is permitted to perform a local calculation of its TA for each base station.

[0147] In the deployment scenario of Figure 7, the LpUE 71 can transmit ULRS to base stations 74-79 for positioning purposes. Each base station 74-79 performs positioning such as time difference of arrival or angle of arrival measurements. The positioning results are transmitted to a location server such as the LMF 199. The LMF 199 performs a position estimation based on the obtained positioning values ​​and the geographical locations of the base stations 74-79. This position estimation is in accordance with the prior art.

[0148] Figure 8 shows a signaling diagram of communications between the UE 101, base stations 112, 113, and LMF 199. When the UE is operating in disconnected mode 801, the UE 101 may be triggered to perform an UL SRS transmission. The UE checks the TA and updates it if necessary. Thus, the UE first performs timing measurements using DL PRS or SSB. The UE updates its TA if necessary and begins UL SRS transmission based on a pre-configured UL SRS configuration. The remainder of the positioning and location estimation is performed according to conventional procedures, which are described in more detail below.

[0149] First, the UE 101 synchronizes with the cellular network 100 while operating in disconnected mode 801. For this purpose, SSBs are received.

[0150] The UE 101 initiates and joins the RACH procedure at 4105. As part of the DL message of the RACH procedure, it obtains a reference TA at box 4110. The serving base station 112 performs timing measurements on the RACH preamble transmitted by the UE, determines the reference TA, and includes the reference TA in RACH message 2 that it transmits in response to the RACH preamble.

[0151] The UE 101 transitions to RRC_Connected mode 802 and performs a communication exchange at 4115. This includes indicating the UE's capability information (as explained in detail in box 3005). RRC configuration and payload data may be communicated. The capability information may be included in RRC control messages communicated on the Physical Shared UL Channel (PUSCH).

[0152] In 4120, the serving base station 112 provides the configuration for locally determining the TA, as detailed above in box 3015.

[0153] In 4125, the base stations 112 and 113 provide the UL SRS configuration to the LMF 199. In other words, the base stations 112 and 113 notify the LMF 199 of the time-frequency resources to be used, etc.

[0154] The message transmitted at 4125 may, in some scenarios, indicate to the LMF 199 that the UE 101 and base stations 112 and 113 support positioning of the UE 101 while the UE 101 is operating in disconnected mode. The message transmitted at 4125 may, among other things, inform the LMF 199 that the UE 101, which is within the coverage area of ​​the base stations 112 and 113, may be permitted to locally determine the TA. One or more of the base stations may not permit the UE 101 to locally determine the TA. Thus, the UE 101 must use conventional procedures for TA acquisition and subsequent UL SRS transmission. Alternatively, one or more of the base stations may permit the UE 101 to locally determine the TA. In this way, the UE 101 uses the locally determined TA before transmitting the UL SRS. See box 3122.

[0155] The UE 101 provides a configuration request message to the LMF 199 at 4126. The configuration request message requests provision of an UL SRS configuration for transmitting UL SRS towards the base stations 112, 113 while operating in disconnected mode 801. The configuration request message is optional. The LMF 199 can also actively provide the UL SRS configuration.

[0156] In 4130, the LMF 199 provides the base stations 112, 113 with UL SRS configuration for their respective spatial contexts. All of these base stations support the UE's local determination of TA. The spatial context does not include base stations that do not allow the UE to locally determine TA. This message requests the transmission of UL SRS while the UE 101 is operating in disconnected mode 801 (see box 3025). This configuration message can be implemented according to the LPP protocol. See 3GPP TS 38.305, version 17.2.0, section 8.13. Each aspect is described in relation to box 3016 with respect to Figure 4.

[0157] The serving base station 112 then sends an RRC Disconnect message to the UE 101 at 4135, which causes the UE 101 to transition to operating in disconnected mode 801. See box 3020.

[0158] In box 4140, the UE is triggered to transmit the UL SRS. There can be various triggering criteria. For example, a request to transmit an uplink reference signal can be obtained from the cellular network (e.g., LMF199) while operating in disconnected mode, as described above in boxes 3025 and 3511.

[0159] Alternatively or additionally, local trigger criteria of the UE are possible, such as a pre-set timing schedule, detection of UE mobility, a mobility level exceeding a certain threshold, a signal from an acceleration sensor, etc.

[0160] The UE then monitors the downlink reference signals, here the DL positioning reference signals at 4145. This has already been described in boxes 3030 and 3031.

[0161] The UE then determines the TA in box 4150 based on timing measurements based on the DL positioning reference signals received in 4145. Techniques have already been described in boxes 3030 and 3032 in particular.

[0162] For example, different options are available for determining the TA based on a combination of a calculated TA based on timing measurements based on the DL PRS received at 4145 and a reference TA obtained at 4110 .

[0163] Then, in 4155, the UE transmits the UL sounding reference signal using the TA determined in 4150 based on the configuration obtained in 4130.

[0164] The base stations 112, 113 perform positioning in 4160 and report the positioning values ​​by providing respective positioning report messages to the LMF 199 in 4165. This corresponds to boxes 3145, 3150, and 3515.

[0165] At 4170, the LMF 199 performs position estimation, using techniques disclosed in 3GPP TS 38.305, version 17.2.0, section 4.3.14, which corresponds to box 3520.

[0166] Figure 9 shows a signaling diagram of communication between the UE 101, base stations 112, 113 and the LMF 199. Figure 9 shows an alternative implementation of the operation of the UE in disconnected mode 801.

[0167] The signaling in Figure 9 generally corresponds to the signaling in Figure 8. However, the process by which the UE 101 obtains a TA has been modified in Figure 9. In particular, in Figure 9, the UE does not monitor DL ​​positioning reference signals as in Figure 8. Instead, the UE transmits random access preambles to the base stations 112 and 113, respectively, at 4146 and 4147. The base stations 112 and 113 respond with random access messages 2, respectively, each of which includes a TA corresponding to the base station 112 and the base station 113. The UE does not continue the RACH procedure, but instead updates its TA for each base station 112 and 113 at 4148 and transmits an UL SRS to each base station 112 and 113 using these TAs at 4155, as already described in Figure 8.

[0168] Figure 10 is a signaling diagram of communications between the UE 101, base stations 112 and 113, and the LMF 199. Figure 10 combines the implementations of Figures 8 and 9. Specifically, the UE performs an attach procedure with base stations 112 and 113 at 4146 and 4147, respectively, and obtains a TA for each base station 112 and 113 as a reference. This TA is then used as a reference to determine the TA at 4150 based on timing measurements for positioning reference signals received at 4145 (typically at a later time). In other words, in the scenario of Figure 10, the UE performs a random access procedure to obtain a reference TA and adjusts the reference TA based on timing measurements for positioning reference signals. Such a scenario is described in box 3034.

[0169] In summary, a technique is disclosed in which a UE pre-configures a coverage area for UL transmission of an RS while the UE is operating in disconnected mode. The coverage area defines a spatial context. The UE self-calculates the TA to be used for UL transmission.

[0170] The UE can either fully calculate the TA (eg, ab initio without a reference) or adjust a previously obtained reference TA.

[0171] The calculation of TA is shown to be guided and assisted by the cellular network, for example, TA calculation rules and / or constraints may be provided.

[0172] The cellular network may also pre-configure the UL transmission of the RS, which may include the spatial direction, i.e., the beam direction, of the UL transmission.

[0173] According to the techniques of this disclosure, the amount of communication required to obtain a TA is minimized.

[0174] The various scenarios of this disclosure are based on the discovery that operating a UE in connected mode consumes significant power. It is desirable for a UE to be able to initiate uplink reference signal transmission and receive configuration even when in disconnected mode. However, when the UE is in disconnected mode, obtaining TA and configuring reference signals (e.g., time and resources for SRS transmission) presents challenges.

[0175] A technique is disclosed in which the UE obtains TA information and reference signal configuration without entering connected mode.

[0176] In summary, at least the following examples are disclosed: Example 1. A method for use in a wireless communication device (71, 101) connected to a cellular network (100), comprising: While operating in a disconnected mode (801), determining a timing advance to facilitate communication with each of one or more base stations (74-79, 112, 113) of the cellular network (100) based on timing measurements of one or more downlink reference signals (4145) transmitted by each of the one or more base stations; transmitting an uplink reference signal (4155) on a time-frequency resource preconfigured according to the timing advance when the wireless communication device (71, 101) determines that the wireless communication device (71, 101) is located within a predefined spatial context (80) and while operating in the disconnected mode; method. Example 2. The method of Example 1, The preconfigured time-frequency resources are allocated for positioning of the wireless communication device. method. Example 3 The method according to Example 1 or 2, further comprising: Obtaining (3025) a request from the cellular network to transmit the uplink reference signal while operating in the disconnected mode. method. Example 4. The method of any one of the preceding examples, comprising: The predefined spatial context is defined by the wireless communication device being located in one or more cells of the cellular network. method. Example 5. The method of any one of the preceding examples, further comprising: obtaining (3015) from the cellular network at least one configuration message related to the determination of the timing advance; method. Example 6. The method of Example 5, the at least one configuration message associated with the determination of the timing advance indicates the predefined spatial context. method. Example 7. The method of any one of the preceding examples, further comprising: Obtaining (3010) at least one of the timing advance tolerance range, the reference timing advance, or the candidate timing advance values ​​from the cellular network. method. Example 8. The method of any one of the preceding examples, comprising: obtaining at least one configuration message associated with the transmission of the uplink reference signal from the cellular network; method. Example 9. The method of Example 8, The at least one configuration message associated with the transmission of the uplink reference signal is provided at least in part by a positioning server (199) of the cellular network. method. Example 10: The method according to Example 8 or 9, the at least one configuration message associated with the transmission of the uplink reference signal indicates the pre-configured time-frequency resources. method.

[0177] While this disclosure has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to those skilled in the art upon reading and understanding the specification, and this disclosure includes all such equivalents and modifications, limited only by the scope of the appended claims.

[0178] For example, the above describes various scenarios in which a UE transmits uplink reference signals for the purpose of UE positioning. In other scenarios, the UE transmits uplink reference signals for other purposes, such as channel sounding. The techniques disclosed herein for determining a timing advance while operating in a disconnected mode are not limited to UE positioning.

Claims

1. A method for use in a wireless communication device (71, 101) connected to a cellular network (100), comprising: While operating in a disconnected mode (801), determining a timing advance for facilitating communication with each of one or more base stations (74-79, 112, 113) of the cellular network (100) based on timing measurements of one or more downlink reference signals (4145) transmitted by each of the one or more base stations; transmitting one or more uplink reference signals (4155) on pre-configured time-frequency resources according to the timing advance when the wireless communication device (71, 101) determines that it is located within a pre-defined spatial context (80) and while operating in the disconnected mode; method.

2. 10. The method of claim 1, The preconfigured time-frequency resources are allocated for positioning of the wireless communication device. method.

3. 3. The method of claim 1 or 2, further comprising: Obtaining (3025) a request from the cellular network to transmit the one or more uplink reference signals while operating in the disconnected mode. method.

4. 4. The method of claim 3, The request is obtained before transitioning to the disconnected mode. method.

5. 4. The method of claim 3, The request is obtained while operating in the disconnected mode. method.

6. 10. A method according to any one of the preceding claims, comprising: The one or more uplink reference signals are uplink positioning reference signals. method.

7. 10. A method according to any one of the preceding claims, comprising: The predefined spatial context is defined by the wireless communication device being located in one or more cells of the cellular network. method.

8. 10. A method according to any one of the preceding claims, comprising: The predefined spatial context is defined by placing the wireless communication device in a geofenced area. method.

9. 10. A method according to any one of the preceding claims, comprising: The predefined spatial context is defined by the wireless communication device receiving a predefined reference signal. method.

10. 10. A method according to any one of the preceding claims, further comprising: obtaining (3015) from the cellular network at least one configuration message related to the determination of the timing advance; method.

11. 11. The method of claim 10, the at least one configuration message related to the determination of the timing advance is provided by a radio access network of the cellular network. method.

12. 12. The method of claim 10 or 11, the at least one configuration message associated with the determination of the timing advance indicates the predefined spatial context. method.

13. 13. The method of claim 12, the predefined spatial context is defined by the wireless communication device being located in one or more cells of the cellular network; The at least one configuration message includes a cell list of cell IDs of each cell of the cellular network that defines the predefined spatial context. method.

14. The method according to any one of claims 10 to 13, The at least one configuration message associated with the determination of the timing advance indicates whether the wireless communication device is authorized to use the timing advance based on the timing measurements. method.

15. The method according to any one of claims 10 to 14, The at least one configuration message related to the determination of the timing advance indicates a calculation rule for determining the timing advance based on the timing measurements. method.

16. The method according to any one of claims 10 to 15, the at least one configuration message associated with the determination of the timing advance indicates a type of the one or more downlink reference signals. method.

17. 10. A method according to any one of the preceding claims, further comprising: Obtaining 3010 at least one of the timing advance tolerance range, the reference timing advance, or the candidate timing advance values ​​from the cellular network. method.

18. 10. A method according to any one of the preceding claims, comprising: The one or more downlink reference signals are at least one of a synchronization signal block or a positioning reference signal. method.

19. 10. A method according to any one of the preceding claims, comprising: obtaining at least one configuration message associated with the transmission of the one or more uplink reference signals from the cellular network; method.

20. 20. The method of claim 19, the at least one configuration message associated with the transmission of the one or more uplink reference signals is provided at least in part by a positioning server (199) of the cellular network. method.

21. 21. The method of claim 19 or 20, the at least one configuration message associated with the transmission of the one or more uplink reference signals is provided at least in part by a radio access network of the cellular network. method.

22. The method according to any one of claims 19 to 21, The at least one configuration message associated with the transmission of the one or more uplink reference signals indicates one or more shared parameters jointly configured for transmitting the one or more uplink reference signals to different base stations among a plurality of base stations of the cellular network. method.

23. The method according to any one of claims 19 to 22, The at least one configuration message associated with the transmission of the one or more uplink reference signals indicates one or more cell-specific parameters individually configured for transmitting the one or more uplink reference signals to different base stations among a plurality of base stations of the cellular network. method.

24. The method according to any one of claims 19 to 23, the at least one configuration message associated with the transmission of the one or more uplink reference signals indicates the pre-configured time-frequency resources. method.

25. The method according to any one of claims 19 to 24, The at least one configuration message associated with the transmission of the one or more uplink reference signals comprises: a frequency start position of the preconfigured time-frequency resource; the preconfigured time-frequency resource band; a frequency stop position of the preconfigured time-frequency resource; Numerology of the preconfigured time-frequency resources; a number of repetitions of the preconfigured time-frequency resources; a repetition rate of the preconfigured time-frequency resources; a comb size of the preconfigured time-frequency resources; a correlation between the preconfigured time-frequency resources and further time-frequency resources on which the downlink reference signals are transmitted; signal characteristics of the one or more uplink reference signals; a spatial relationship of the one or more uplink reference signals; or beamforming parameters of the transmission of the one or more uplink reference signals Indicates one or more of method.

26. 10. A method according to any one of the preceding claims, further comprising: determining a transmit beam for the transmission of the one or more uplink reference signals based on the one or more downlink reference signals; method.

27. 10. A method according to any one of the preceding claims, further comprising: forming (3032) a propagation time of the one or more downlink reference signals based on the timing measurements; The timing advance is determined based on the propagation time. method.

28. 10. A method according to any one of the preceding claims, further comprising: comparing (3033) the timing advance with at least one of a timing advance tolerance range, a reference timing advance, or a candidate timing advance value; Discarding or maintaining the timing advance in response to the comparison. method.

29. 10. A method according to any one of the preceding claims, comprising: The determining of the timing advance includes performing a random access procedure to obtain a reference timing advance and adjust the reference timing advance based on the timing measurement. method.

30. A method for use in a node (71-79, 112, 113, 199) of a cellular network, comprising: providing (4120) at least one configuration message to a wireless communication device (71, 101), the at least one configuration message being associated with the wireless communication device determining a timing advance for transmission of one or more uplink reference signals based on timing measurements based on downlink reference signals transmitted by one or more base stations of the cellular network; triggering (4155) the one or more base stations to monitor the one or more uplink reference signals transmitted by the wireless communication device while operating in a disconnected mode; Contains method.

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