Signalling SL PRS sequence generation

Abstract

Embodiments of the present disclosure relate to apparatuses, methods, and computer readable storage media for dynamic control of sidelink reference signal configuration. In the methods, a first apparatus transmits, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal. Then, the first apparatus performs sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode. In this way, overhead in sidelink positioning can be reduced, and confidentiality can be maintained.

Description

SIGNALLING SL PRS SEQUENCE GENERATIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from, and the benefit of, US Provisional Application No. 63 / 516650, filed July 31, 2023, the contents of which are hereby incorporated by reference in their entirety.FIELDS

[0002] Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for dynamic control of sidelink (SL) reference signal configuration.BACKGROUND

[0003] Location-awareness is a fundamental aspect of wireless communication networks and will enable a myriad of location-enabled services in different applications. Location information may be obtained by various positioning technologies.

[0004] SL positioning is one of the positioning technologies, which is based on the transmissions of SL positioning reference signal (SL-PRS) between an anchor and a target user equipment (UE) to enable localization of the target UE within precise latency and accuracy requirements of the corresponding SL positioning session. In a SL positioning scenario, a target UE may perform a SL positioning process, for example, by exchanging SL-PRS with one or more anchor UEs to determine its location. In some situations, a target UE may perform self-positioning to localize itself based on PRS signal(s) from neighboring anchor UEs.SUMMARY

[0005] In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: transmit, to at least one of a second apparatus or a third apparatus, a request forswitching to a target transmission mode of a sidelink reference signal; and perform sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

[0006] In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: receive, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and perform sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

[0007] In a third aspect of the present disclosure, there is provided a third apparatus. The third apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus at least to: receive, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and transmit, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

[0008] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: transmitting, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and performing sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

[0009] In a fifth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and performing sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

[0010] In a sixth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and transmitting, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

[0011] In a seventh aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for transmitting, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

[0012] In an eighth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for receiving, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

[0013] In a ninth aspect of the present disclosure, there is provided a third apparatus. The third apparatus comprises means for receiving, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for transmitting, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

[0014] In a tenth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fourth aspect.

[0015] In an eleventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fifth aspect.

[0016] In a twelfth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the sixth aspect.

[0017] It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0019] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0020] FIG. 2A illustrates a signaling chart for dynamic control of SL reference signal configuration according to some example embodiments of the present disclosure;

[0021] FIG. 2B illustrates a signaling chart for dynamic control of SL reference signal configuration according to some example embodiments of the present disclosure;

[0022] FIG. 3A illustrates a signaling chart for switching transmission modes of sidelink reference signals according to some example embodiments of the present disclosure;

[0023] FIG. 3B illustrates a further signaling chart for switching transmission modes of sidelink reference signals according to some example embodiments of the present disclosure;

[0024] FIG. 4 illustrates a still further signaling chart for switching transmission modes of sidelink reference signals according to some example embodiments of the present disclosure;

[0025] FIG. 5 illustrates a flowchart of a method implemented at a first apparatus according to some example embodiments of the present disclosure;

[0026] FIG. 6 illustrates a flowchart of a method implemented at a second apparatus according to some example embodiments of the present disclosure;

[0027] FIG. 7 illustrates a flowchart of a method implemented at a third apparatus according to some example embodiments of the present disclosure;

[0028] FIG. 8 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0029] FIG. 9 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0030] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0031] Principle of the present disclosure will now be described with reference to someexample embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

[0032] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0033] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0034] It shall be understood that although the terms “first,” “second,”..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0035] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0036] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0038] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0039] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0040] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), the sixth generation (6G) communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0041] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0042] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT).The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0043] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0044] FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. In the communication environment 100, there are a plurality of communication devices, for example, a first apparatus 110, a second apparatus 120, and a third apparatus 130. Any two of the three apparatus can communication with each other.

[0045] SL positioning (including ranging) have been supported in NR systems. Forinstance, it has been specified signalling and associated UE behavior for support of unicast, groupcast (not including many to one) and broadcast of SL PRS transmissions. Meanwhile, reporting signalling and procedures have been studied to facilitate support of SL positioning in all coverage scenarios and for PC5-only and joint PC5-Uu scenarios. Furthermore, procedures for SL positioning between UEs (Protocol for Sidelink positioning procedures (SLPP)), as well as procedures for SL positioning between UEs and Location Management Function (LMF), are also under discussion.

[0046] As used herein, the term “Target UE” refers to a UE to be positioned (in this context, using SL, i.e., PC5 interface).

[0047] The term “anchor” or “anchor UE” refers to a UE supporting positioning of target UE, e.g., by transmitting and / or receiving reference signals for positioning, providing positioning-related information, etc., over the SL interface.

[0048] The term “server UE” refers to a SL Positioning Server UE, which is a UE offering method determination, assistant data distribution and / or location calculation functionalities for Sidelink Positioning and Ranging based service.

[0049] The term “sidelink positioning” refers to that a positioning UE uses reference signals transmitted over SL, i.e., PC5 interface, to obtain absolute position, relative position, or ranging information.

[0050] The term “ranging” refers to determination of the distance and / or the direction between a UE and another entity, e.g., anchor UE.

[0051] The term “sidelink positioning reference signal (SL PRS or SL-PRS)” refers to a reference signal transmitted over SL for positioning purposes.

[0052] The term “SL PRS (pre-)configuration” refers to (pre-)configured parameters of SL PRS such as time-frequency resources (other parameters are not precluded) including its bandwidth and periodicity.

[0053] SL positioning is based on the transmissions of positioning reference signal SL- PRS between the anchor and target UEs to enable localization of the target UE within precise latency and accuracy requirements of the corresponding SL positioning session.

[0054] Before and after the transmission and measurement of the SL PRSs, a series of steps may be taken place to enable SL positioning. Discovery procedure may be includedin the sidelink positioning procedure at least for out of coverage scenario. Discovery messages may be used to carry information for targeted discovery and candidate selection of SL positioning UEs, including at least the indication of anchor UE, target UE. and server UE roles.

[0055] In example embodiments of FIG. 1 the first apparatus 110 may be an impacted terminal device, the second apparatus 120 may be a terminal device for transmitting the SL reference signal, and the third apparatus 130 may be a decision-making device.

[0056] As used herein, the term “impacted terminal device” may be a target UE, which does not belong to a positioning session of an anchor UE, but would like to overhear its PRS. Alternatively, or in addition, the impacted terminal device may be a member of a positioning session that would like to prevent non-members to overhear (its) PRS.

[0057] In example embodiments of the present disclosure, the “impacted terminal device” may be a UE that deems the usage of a current transmission mode of the SL PRS as unsatisfactory and would like to have it changed (to a different transmission mode). In other words, the “impacted terminal device” may be a UE that either actively receives or transmits an SL PRS. This could be either the target UE or the anchor UE but not a standalone server UE.

[0058] As used herein, the term “terminal device for transmitting the SL reference signal” may be referred to as a PRS -transmitting device or a PRS -transmitting terminal device, for example, a PRS -transmitting UE. The PRS -transmitting device may be, for instance, the anchor UE and / or the target UE.

[0059] As used herein, the term “decision-making device” refers to a device that makes decision(s) in a positioning session. For example, decision-making device may be the server UE and / or the LMF, but potentially it could be also the target UE as SA2 envisages the anchor- selection capability and other privileges to it.

[0060] In the following, for the purpose of illustration, some example embodiments are described with the first apparatus 110 operating as an impacted device, the second apparatus 120 operating as a PRS-transmitting device, and the third apparatus 130 operating as a decision-making device. However, it is to be understood that the above examples are just discussed for purpose of illustrations rather than limitations.

[0061] Communications in the communication environment 100 may be implementedaccording to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple -Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0062] In legacy positioning, a target UE is always provided with assistance data (AD) containing a full description of anchor / TRP identity together with the exact configuration of their PRS signals. This information then permits the target UE to successfully receive, correctly decode and accurately evaluate the pre-configured PRS. All these steps are critical for the subsequent localization process, executed in the UE or LMF. Similarly, target UE can request and be provided with assistance data related to SL PRS and location computation can be performed at LMF or server UE. In SL positioning, the server UE functionality can be hosted within the target UE. Here, the assistance data may include SL PRS sequence ID(s) using which target can identify the sequence(s) transmitted by the anchor UEs.

[0063] However, latency-sensitive (and / or power saving, low complexity) target / server UEs who would like to engage in session-less self-positioning, that is, quickly localize themselves by efficiently reusing existing neighboring anchor UEs and their preconfigured PRSs without any lengthy signaling with other UEs need to resolve the problem of how to successfully receive PRS from a neighboring anchor UE for which no prior assistance data was obtained or the PRS for which the UE is not an intended recipient.

[0064] The conventional solutions to this problem would consist in blind brute-force decoding, that is, trial-and-error correlating the received unknown PRS signal with all PRS instances generated from all standardized pseudo-random sequences, comb types, bandwidth, etc., sequentially exploring the entire parameter space. This process howeverwould be extremely intense in terms of time and computational / memory resources, given the large number of possible PRS instances.

[0065] According to some example embodiments of the present disclosure, there is provided a solution for dynamic control of SL reference signal configuration. More specifically, the PRS-transmitting device may dynamically switch between different transmission modes of SL reference signals without any (direct) signalling interaction with the PRS-receiving device, importantly also including UEs which do not belong to its own positioning session such as session-less UEs only overhearing the PRS transmission.

[0066] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0067] FIG. 2A illustrates a signaling chart 200A for dynamic control of sidelink reference signal (SL RS) configuration according to some example embodiments of the present disclosure. For the purposes of discussion, the signaling chart 200A will be discussed with reference to FIG. 1, for example, by using the first apparatus 110, the second apparatus 120 and the third apparatus 130.

[0068] The SL RS discussed herein may comprise various reference signals, for example, but not limited to, sidelink positioning reference signal (SL PRS or SL-PRS). For purpose of the discussion, in example embodiments of the present disclosure, the SL RS may be sometimes discussed as SL PRS.

[0069] The transmission mode of the reference signal may be a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0070] In some example embodiments, for SL PRS sequence generation, one of the following options (i.e., transmission modes) may be down-selected to define the parameter ’sPqS, which is the identification of the sequence of the SL PRS:

[0071] First Option (first transmission mode): n psPqSis a higher layer parameter.

[0072] Second Option (second transmission mode):is based on 12 LSB bitsCyclic redundancy check (CRC) of sidelink control information (for example, Physical Sidelink Control Channel (PSCCH)) associated with the SL PRS.

[0073] In some alternative or additional cases, for SL PRS sequence generation, the parameter nipis defined as below: the parameter nipis provided by higher layers to a transmitting (Tx) UE. Details on higher layers, including consideration of Tx UE’s own higher layer, may be up to network structures / requirements. The higher layer parameter is provided to a receiving (Rx) UE via long term evolution positioning protocol (LPP) or Sidelink Positioning Protocol (SLPP). Otherwise, i.e., if the parameteris not provided by higher layers, the parameter tinySeq is based on 12 LSB bits CRC of PSCCH associated with the SL PRS.

[0074] In example embodiments shown with respect to FIG. 2, the first apparatus 110 may be an impacted terminal device, for example, an “impacted” UE. The second apparatus 120 may be a terminal device for transmitting the SL reference signal. In some example embodiments, the SL reference signal may be a SL PRS, and the second apparatus 120 may be a SL-PRS transmitting device, for example, a “PRS-transmitting” UE. The third apparatus 130 may be a decision-making device, for example, a server UE or a LMF.

[0075] In some example embodiments, the “impacted” UE may determine that above mentioned first option or second option employed by the “PRS-transmitting” UE for a given PRS of interest is undesirable. For example, a session-less target UE fails to decode an overheard PRS of interest due to the usage of the first option. In another example, a sensitive UE joins a positioning session employing the second option, permitting its undesirable localization by other (unauthorized) UEs, particularly relevant in group positioning and / or group mobility.

[0076] In some example embodiments, the “impacted” UE may indicate the undesirability issue to the “PRS-transmitting” UE and / or a “decision-making” device. For example, the impacted UE may broadcast to neighboring UEs including the transmitting (target or anchor) UEs and / or the server UE. Alternatively or additionally, the impacted UE may deliver a unicast message to the associated server UE or LMF. Thereby, a relay or forwarding node may be used as well to deliver the message to its destination.

[0077] In some example embodiments of the present disclosure, no additional feedback is provided to the “impacted” UE on the change of PRS transmission option, e.g., so as to ensure the session-less nature of autonomous self-positioning and / or reduce overhead and maintain confidentiality. The signaling chart 200A illustrates such a situation.

[0078] In the signaling chart 200A, the first apparatus 110 transmits (210), to at least one of the second apparatus 120 or the third apparatus 130, a request for switching to a target transmission mode of a sidelink reference signal.

[0079] In some example embodiments, the first apparatus 110 may determine that a current transmission mode of the sidelink reference signal, and thus transmit the request indicating the undesirability to at least one of the second apparatus or the third apparatus. The request may indicate a target transmission mode different the current transmission mode, meaning that the transmission mode of the reference signal is desired / required to be switch from the current transmission mode to the target transmission mode.

[0080] Then, the first apparatus 110 performs sidelink positioning (250) with at least one of the second apparatus 120 and the third apparatus 130 based on the target transmission mode.

[0081] As for the second apparatus 120, it receives (215) the request from the first apparatus 110, and performs the sidelink positioning (250) with the first apparatus based on the target transmission mode in response to receiving the request.

[0082] In this way, the session-less nature of autonomous self-positioning can be ensured, overhead can be reduced, and confidentiality can be maintained.

[0083] As an alternative, in some example embodiments, the authorization of “impacted” UE may be verified. For example, LMF may verify if the “impacted” UE is eligible for the reception of PRS of interest.

[0084] In some example embodiments, the PRS of interest may be transmitted by using the alternative transmission mode. For example, a time-limited switch from the first option to the second option or from the second option to the first option may be executed by the “PRS -transmitting” UE, possibly based on signaling with “decision-making” UE. The PRS transmitting UE may select the PRS transmission option based on also a location and time-based option selection configuration that is provided by LMF or server UE. By way of example, LMF may identify a geographical area where trusted UEs are present (e.g. factory premises) and associate that area with the second option. When PRS transmitting UE is in the indicated area, it would use the second option. Details regarding switching of transmission modes of a reference signal based on indication from the “decision-making” UE will be discussed with respect to FIG. 2B.

[0085] FIG. 2B illustrates a signaling chart 200B for dynamic control of sidelink reference signal (SL RS) configuration according to some example embodiments of the present disclosure. Similar to FIG. 2A, the signaling chart 200B will be discussed with reference to FIG. 1, for example, by using the first apparatus 110, the second apparatus 120 and the third apparatus 130.

[0086] In the signaling chart 200B, the first apparatus 110 transmits (210), to at least one of the second apparatus 120 or the third apparatus 130, a request for switching to a target transmission mode of a sidelink reference signal. In some example embodiments, the first apparatus 110 may determine that a current transmission mode of the side link reference signal, and thus transmit the request indicating the undesirability to at least one of the second apparatus or the third apparatus. The request may indicate a target transmission mode different the current transmission mode, meaning that the transmission mode of the reference signal is desired / required to be switch from the current transmission mode to the target transmission mode.

[0087] As discussed above with respect to the signaling chart 200A, in some embodiments, the second apparatus 120, in response to receiving (215) the request, may directly switch to the target transmission mode, for example, switch from a previously- used transmission mode to the target transmission mode. That is, upon receiving (215) the request, the second apparatus 120 directly performs (250) side link positioning with at least one of the first apparatus 110 and the third apparatus 130 based on the target transmission mode.

[0088] Alternatively, as shown in FIG.2B, the second apparatus 120 may check with the third apparatus 130, that is the decision-making device (e.g., LMF) whether this request is validated. This is an indirect satisfaction of the request because the LMF is involved as the decision-making node.

[0089] Specifically, the second apparatus 120, upon receiving (215) the request, may indicate the request to the third apparatus 130. In response to receiving (235) an indication of the target transmission mode, from the third apparatus 130, the second apparatus 120, performs the sidelink positioning with the first apparatus based on the target transmission mode. The indication may be transmitted from the third apparatus 130 in accordance with a determination that the request is validated.

[0090] In some example embodiments, the third apparatus 130 may receive (220) therequest from the first apparatus 110. Alternatively, the request may be transmitted from the first apparatus 110 to the second apparatus 120, and the second apparatus 120 may forward or indicate the request to the third apparatus 130.

[0091] From the perspective of the third apparatus 130, the request may be received (220) from the first apparatus 110, for example, by unicast. Alternatively, the request may be received (220) from the second apparatus 120. In this situation, the request may be transmitted from the first apparatus 110 to the second apparatus 120, for example, by unicast, groupcast or broadcast, and the second apparatus 120 indicates the request to the third apparatus 130.

[0092] In some embodiments, the third apparatus 130 may determine whether the request is validated based on checking of at least one of a credential, a priority, or authorization information of the first apparatus with respect to session members in a positioning process. If the third apparatus 130 determines that the request is validated, it transmits (230) an indication of the target transmission mode. The indication of the target transmission mode may be indicated or included in assistance data transmitted from the third apparatus 130, or may be included or carried by other suitable signaling / data.

[0093] The first apparatus 110, in response to receiving (240), from the third apparatus 130, an indication of the target transmission mode, may perform (250) the sidelink positioning with the second apparatus based on the target transmission mode. As discussed above, the indication is transmitted in accordance with a determination that the request is validated at the third apparatus 130.

[0094] In some scenarios, a terminal device, e.g., a UE, may self-position itself based on over-hearing SL PRS from neighboring anchor UEs that have been configured to serve a target UE within its own positioning session. More details of these example embodiments of the present disclosure will be discussed with respect to FIGS. 3 A and 3B. FIG. 3A illustrates a signaling chart 300A for self-positioning according to some example embodiments of the present disclosure, and FIG. 3B illustrates another signaling chart 300B for self-positioning according to some example embodiments of the present disclosure. For simplicity, only one anchor UE 303 is shown in FIGS 3 A and 3B.

[0095] As shown in FIG. 3A, the target UE 302, the anchor UE 303 and the LMF 304 perform a positioning session setup procedure 310. Then, the LMF 304 transmits (315) an identification of the target transmission mode (for example, the first transmission mode(also referred to as the first option)) of SL PRS to both the target UE 302 and the anchor UE 303. In some embodiments, the LMF 304 transmits the identification (for example, by means of assistance data) via a higher layer signaling. According to the first transmission mode, the anchor UE 303 transmits (320) SL PRS to both the target UE 302 and the selfpositioning UE 301.

[0096] For purpose of illustration, it is assumed that the anchor UE 303 was configured by the LMF 304 to transmit its SL PRS by using the above-mentioned first option. This however prevents the self-positioning UE 301 from quickly and efficiently decoding the SL PRS, as only blind “brute-force” search of the PRS configuration (e.g., the sequence number) is possible. For example, the self-positioning UE 301 may determine (325) a SL PRS decoding failure. To this end, the impacted self-positioning UE 301 transmits (330) a request of a switch to the second transmission mode (also referred to as the second option). As shown in FIG. 3A, the request for switch to the second option may be transmitted (330) directly to the decision-making node, e.g., LMF 304.

[0097] The LMF 304 evaluates (335) whether this request is appropriate. For example, the request validation may be performed by checking the credentials, priority, or authorization of the requesting UE with respect to those of the session members, i.e., the target UE 302 and its anchor UE 303. If approvable, the LMF 304 reconfigures the PRS delivery mode to the second option.

[0098] Then, the LMF 304 transmits (340) an indication of the target transmission mode (in this example, the second option) by using assistance data to both the target UE 302 and the anchor UE 303. Upon receiving the indication of the target transmission mode, the anchor UE 303 may transmit (345) SL PRS according to the target transmission mode, to both the target UE 302 and the self-positioning UE 301. As such, the self-positioning UE 301 may decode (350) SL PRS successfully.

[0099] Alternatively, the PRS -transmitting UE may also perform a (time-limited) switch from the first option to the second option. Upon failing to decode the PRS based on the pre-configured the first option, the target UE 302 may test the second option approach an succeed. In this way, no extra signaling overhead is introduced.

[0100] Now turn to FIG. 3B, in which the target UE 302, similar to embodiments shown with respect to FIG. 3A, the anchor UE 303 and the LMF 304 perform a positioning session setup process 310. The LMF 304 transmits (315) the indication of the targettransmission mode (for example, the second option) of PRS to both the target UE 302 and the anchor UE 303. The anchor UE 303 transmits (320) SL PRS 320 to both the target UE 302 and the self-positioning UE 301.

[0101] For purpose of illustration, it is assumed that the anchor UE 303 was configured by the LMF 304 to transmit its SL PRS by using the above-mentioned first option. This however prevents the self-positioning UE 301 from quickly and efficiently decoding the SL PRS, as only blind “brute-force” search of the PRS configuration (e.g., the sequence number) is possible. For example, the self-positioning UE 301 may determine (325) that a SL PRS decoding failure occurs. To this end, the impacted self-positioning UE 301 transmit (355) a request of a switch to the second option. The request may be transmitted (355) to the target UE 302 and the anchor UE 303 in way of broadcasting. The anchor UE 303 may further indicate (for example, forward) (360) the request to the decisionmaking node, e.g., LMF 304.

[0102] The LMF 304 evaluates (335) whether this request is appropriate. For example, the request validation may be performed by checking the credentials, priority, or authorization of the requesting UE with respect to those of the session members, i.e., the target UE 302 and its anchor UE 303s. If approvable, the LMF 304 reconfigures the PRS delivery mode to the second option.

[0103] Then, the LMF 304 transmits (340) an indication of the target transmission mode (in this example, the second option) by using assistance data to both the target UE 302 and the anchor UE 303. Upon receiving the indication of the target transmission mode, the anchor UE 303 may transmit (345) SL PRS according to the target transmission mode, to both the target UE 302 and the self-positioning UE 301. As such, the self-positioning UE 301 may decode (350) SL PRS successfully.

[0104] In some alternative example embodiments, a new location-sensitive member of a group-positioning session ensures that no PRS overhearing is possible, for example to prevent its own localization by unauthorized UEs. This is done by triggering a switch from the second option to the first option. More details of these example embodiments of the present disclosure will be discussed with respect to FIG 4, which illustrates a further signaling chart 400 for self-positioning according to some example embodiments of the present disclosure.

[0105] As shown in FIG. 4, there may be more than one target UE. In this example,there shows two target UEs, target UE1 403 and target UE2 402. As shown, a standard positioning session 410 is first setup for target UE1 403. Then, LMF 405 transmits (415) assistance data to both the target UE1 403 and the anchor UE 404 according to, for example, the second transmission mode (the second option) of SL PRS. It is to be understood that, in example embodiments of FIGs. 3A to 4, LMF 405 is just an example rather than limitation. The LMF 405 may be replaced with a server UE in other example embodiments of the present disclosure.

[0106] Then, the target UE2 402 joins the session which is then extended to a group- positioning session 420 as per SA2 agreements. Then, the LMF 405 transmits (425) assistance data the target UE2 402, the target UE1 403 and the anchor UE 404, such that they can perform SL positioning according to the current transmission mode of PRS, i.e., the second option.

[0107] For purpose of illustration, it is assumed that RTT is used as the positioning method and all session member UEs would take turns transmitting their SL PRS using the second option. However, this would permit to localize the session members by an unauthorized UE such as the self-positioning UE 401 who is able to overhear the SL PRS transmissions.

[0108] As shown in FIG. 4, the self-positioning UE 401, target UE1 403, target UE 2 and anchor UE 404 may decode (430) the SL PRS successfully. The location-sensitive target UE2 402 may determine (435) there is a need for the first transmission mode of the PRS, i.e., the first option. The target UE2 402 transmits (440) a request 440 for the usage of the first option to the LMF 405. The LMF 405, upon verification (445) of the request, re-configures the session and provides the members with the first option SL PRS configuration by an assistance data update. The LMF 405 transmits (450) assistance data including an indication of the first option, to the anchor UE 404, target UE1 403, and target UE2 402, to indicate that the first option is to be used in the subsequent SL positioning process.

[0109] The anchor UE 404, the target UE1 403 and target UE2 402 decodes (455) SL PRS successfully. Moreover, the anchor UE 404, the target UE1 403 and target UE2 402 decodes (460) SL PRS unsuccessfully. That is, a SL PRS decoding failure occurs at the self-positioning UE 401. This prevents any UEs outside of the positioning session such as the self-positioning UE 401 overhearing their SL PRS transmission to decode thesuccessfully.

[0110] In view of the above, the solutions according to some example embodiments of the present disclosure can advantageously enable dynamic switch between the above mentioned first option and second option for PRS delivery without any (direct) signaling interaction with the PRS-receiving UE, importantly also including UEs not belonging to its own positioning session, such as session-less UEs only overhearing the PRS transmission.

[0111] FIG. 5 shows a flowchart of an example method 500 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0112] At block 510, the first apparatus 110 transmits, to at least one of a second apparatus 120 or a third apparatus 130, a request for switching to a target transmission mode of a sidelink reference signal.

[0113] At block 520, the first apparatus 110 performs sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

[0114] In some example embodiments, the request is transmitted to the second apparatus, and the second apparatus performs the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

[0115] In some example embodiments, the request is transmitted to the third apparatus, or the request is transmitted to the second apparatus, and the second apparatus indicates the request to the third apparatus.

[0116] In some example embodiments, the method 500 further comprises: in response to receiving, from the third apparatus, an indication of the target transmission mode, performing the sidelink positioning with the second apparatus based on the target transmission mode. The indication is transmitted in accordance with a determination that the request is validated.

[0117] In some example embodiments, the method 500 further comprises: determining that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode; and transmitting the request indicating the undesirability to at least one of the second apparatus or the thirdapparatus.

[0118] In some example embodiments, the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0119] In some example embodiments, the first apparatus 110 comprises an impacted terminal device, the second apparatus 120 comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus 130comprises a decision-making device.

[0120] FIG. 6 shows a flowchart of an example method 600 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0121] At block 610, the second apparatus 120 receives, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal.

[0122] At block 620, the second apparatus 120 performs sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

[0123] In some example embodiments, the method 600 further comprises: performing the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

[0124] In some example embodiments, the method 600 further comprises: indicating the request to the third apparatus; and in response to receiving, from the third apparatus, an indication of the target transmission mode, performing the sidelink positioning with the first apparatus based on the target transmission mode. The indication is transmitted in accordance with a determination that the request is validated.

[0125] In some example embodiments, the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

[0126] In some example embodiments, the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higherlayer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0127] In some example embodiments, the first apparatus 110 comprises an impacted terminal device, the second apparatus 120 comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus 130 comprises a decision-making device.

[0128] FIG. 7 shows a flowchart of an example method 700 implemented at a third device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the third apparatus 130 in FIG. 1.

[0129] At block 710, the third apparatus 130 receives, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal.

[0130] At block 720, the third apparatus 130 transmits, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

[0131] In some example embodiments, the method 700 further comprises: determining whether the request is validated based on checking of at least one of a credential, a priority, or authorization information of the first apparatus with respect to session members in a positioning process; and in accordance with a determination that the request is validated, transmitting the indication of the target transmission mode.

[0132] In some example embodiments, the request is received from the first apparatus, and the first transmitted the request to the third apparatus.

[0133] In some example embodiments, the request is received from the second apparatus, and the request is transmitted from the first apparatus to the second apparatus, and the second apparatus indicates the request to the third apparatus.

[0134] In some example embodiments, the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

[0135] In some example embodiments, the target transmission mode is one of: a firstmode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0136] In some example embodiments, the first apparatus 110 comprises an impacted terminal device, the second apparatus 120 comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus 130 comprises a decision-making device.

[0137] In some example embodiments, a first apparatus capable of performing any of the method 500 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1.

[0138] In some example embodiments, the first apparatus comprises means for transmitting, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

[0139] In some example embodiments, the request is transmitted to the second apparatus, and the second apparatus performs the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

[0140] In some example embodiments, the request is transmitted to the third apparatus, or the request is transmitted to the second apparatus, and the second apparatus indicates the request to the third apparatus.

[0141] In some example embodiments, the first apparatus further comprises: means for in response to receiving, from the third apparatus, an indication of the target transmission mode, performing the sidelink positioning with the second apparatus based on the target transmission mode. The indication is transmitted in accordance with a determination that the request is validated.

[0142] In some example embodiments, the first apparatus further comprises: means for determining that a current transmission mode of the sidelink reference signal isundesirable, the current transmission mode being different from the target transmission mode; and means for transmitting the request indicating the undesirability to at least one of the second apparatus or the third apparatus.

[0143] In some example embodiments, the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0144] In some example embodiments, the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus comprises a decision-making device.

[0145] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of the method 500 or the first apparatus 110. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the first apparatus.

[0146] In some example embodiments, a second apparatus capable of performing any of the method 600 (for example, the second apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

[0147] In some example embodiments, the second apparatus comprises means for receiving, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

[0148] In some example embodiments, the request is transmitted to the second apparatus. The second apparatus further comprises: means for performing the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

[0149] In some example embodiments, the request is transmitted to the second apparatus. The second apparatus further comprises: means for indicating the request tothe third apparatus; and means for in response to receiving, from the third apparatus, an indication of the target transmission mode, performing the sidelink positioning with the first apparatus based on the target transmission mode. The indication is transmitted in accordance with a determination that the request is validated.

[0150] In some example embodiments, the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

[0151] In some example embodiments, the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0152] In some example embodiments, the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus comprises a decision-making device.

[0153] In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of the method 600 or the second apparatus 120. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the second apparatus.

[0154] In some example embodiments, a third apparatus capable of performing any of the method 700 (for example, the third apparatus 130 in FIG. 1) may comprise means for performing the respective operations of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The third apparatus may be implemented as or included in the third apparatus 130 in FIG. 1.

[0155] In some example embodiments, the third apparatus comprises means for receiving, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for transmitting, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

[0156] In some example embodiments, the third apparatus further comprises: means fordetermining whether the request is validated based on checking of at least one of a credential, a priority, or authorization information of the first apparatus with respect to session members in a positioning process; and means for in accordance with a determination that the request is validated, transmitting the indication of the target transmission mode.

[0157] In some example embodiments, the request is received from the first apparatus, and the first transmitted the request to the third apparatus.

[0158] In some example embodiments, the request is received from the second apparatus, and the request is transmitted from the first apparatus to the second apparatus, and the second apparatus indicates the request to the third apparatus.

[0159] In some example embodiments, the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

[0160] In some example embodiments, the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

[0161] In some example embodiments, the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus comprises a decision-making device.

[0162] In some example embodiments, the third apparatus further comprises means for performing other operations in some example embodiments of the method 700 or the third apparatus 130. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the third apparatus.

[0163] FIG. 8 is a simplified block diagram of a device 800 that is suitable for implementing example embodiments of the present disclosure. The device 800 may be provided to implement a communication device, for example, the first apparatus 110, the second apparatus 120 or the third apparatus 130 as shown in FIG. 1. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processor 810, and one or more communication modules 840 coupled to the processor 810.

[0164] The communication module 840 is for bidirectional communications. The communication module 840 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 840 may include at least one antenna.

[0165] The processor 810 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0166] The memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 824, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 822 and other volatile memories that will not last in the power-down duration.

[0167] A computer program 830 includes computer executable instructions that are executed by the associated processor 810. The instructions of the program 830 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 830 may be stored in the memory, e.g., the ROM 824. The processor 810 may perform any suitable actions and processing by loading the program 830 into the RAM 822.

[0168] The example embodiments of the present disclosure may be implemented by means of the program 830 so that the device 800 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 7. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0169] In some example embodiments, the program 830 may be tangibly contained in acomputer readable medium which may be included in the device 800 (such as in the memory 820) or other storage devices that are accessible by the device 800. The device 800 may load the program 830 from the computer readable medium to the RAM 822 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0170] FIG. 9 shows an example of the computer readable medium 900 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 900 has the program 830 stored thereon.

[0171] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0172] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non- transitory computer readable medium. The computer program product includes computerexecutable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0173] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0174] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0175] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0176] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separatelyor in any suitable sub-combination.

[0177] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: transmit, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and perform sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

2. The first apparatus of claim 1, wherein the request is transmitted to the second apparatus, and the second apparatus performs the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

3. The first apparatus of claim 1, wherein the request is transmitted to the third apparatus, or wherein the request is transmitted to the second apparatus, and the second apparatus indicates the request to the third apparatus.

4. The first apparatus of claim 3, wherein the first apparatus is caused to: in response to receiving, from the third apparatus, an indication of the target transmission mode, perform the sidelink positioning with the second apparatus based on the target transmission mode, wherein the indication is transmitted in accordance with a determination that the request is validated.

5. The first apparatus of any of claims 1 to 4, wherein the first apparatus is caused to: determine that a current transmission mode of the sidelink reference signal isundesirable, the current transmission mode being different from the target transmission mode; and transmit the request indicating the undesirability to at least one of the second apparatus or the third apparatus.

6. The first apparatus of any of claims 1 to 5, wherein the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

7. The first apparatus of any of claims 1 to 6, wherein the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus comprises a decisionmaking device.

8. A second apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: receive, from a first apparatus, a request for switching to a target transmission mode of a side link reference signal; and perform sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

9. The second apparatus of claim 8, wherein the request is transmitted to the second apparatus, and the second apparatus is caused to: perform the sidelink positioning with the first apparatus based on the target transmission mode in response to receiving the request.

10. The second apparatus of claim 8, wherein the request is transmitted to the second apparatus, and the second apparatus is caused to: indicate the request to the third apparatus; and in response to receiving, from the third apparatus, an indication of the target transmission mode, perform the sidelink positioning with the first apparatus based on the target transmission mode, wherein the indication is transmitted in accordance with a determination that the request is validated.

11. The second apparatus of any of claims 8 to 10, wherein the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

12. The second apparatus of any of claims 8 to 11, wherein the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

13. The second apparatus of any of claims 8 to 12, wherein the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal device for transmitting the sidelink reference signal, and the third apparatus comprises a decision-making device.

14. A third apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus at least to: receive, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and transmit, to at least one of the first apparatus or the second apparatus, an indicationof the target transmission mode for sidelink positioning.

15. The third apparatus of claim 14, wherein the third apparatus is caused to: determine whether the request is validated based on checking of at least one of a credential, a priority, or authorization information of the first apparatus with respect to session members in a positioning process; and in accordance with a determination that the request is validated, transmit the indication of the target transmission mode.

16. The third apparatus of claim 14 or 15, wherein the request is received from the first apparatus, and wherein the first apparatus transmitted the request to the third apparatus.

17. The third apparatus of claim 14 or 15, wherein the request is received from the second apparatus, and wherein the request is transmitted from the first apparatus to the second apparatus, and the second apparatus indicates the request to the third apparatus.

18. The third apparatus of any of claims 14 to 17, wherein the request indicates that a current transmission mode of the sidelink reference signal is undesirable, the current transmission mode being different from the target transmission mode.

19. The third apparatus of any of claims 14 to 18, wherein the target transmission mode is one of: a first mode that an identification of the sidelink reference signal is to be transmitted via a higher layer signaling, or a second mode in which the identification of the sidelink reference signal is to be transmitted via sidelink control information.

20. The third apparatus of any of claims 14 to 19, wherein the first apparatus comprises an impacted terminal device, the second apparatus comprises a terminal devicefor transmitting the sidelink reference signal, and the third apparatus comprises a decision-making device.

21. A method comprising: transmitting, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and performing sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

22. A method comprising: receiving, from a first apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and performing sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

23. A method comprising: receiving, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and transmitting, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

24. A first apparatus comprising: means for transmitting, to at least one of a second apparatus or a third apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the second apparatus and the third apparatus based on the target transmission mode.

25. A second apparatus comprising: means for receiving, from a first apparatus, a request for switching to a targettransmission mode of a sidelink reference signal; and means for performing sidelink positioning with at least one of the first apparatus and a third apparatus based on the target transmission mode.

26. A third apparatus comprising: means for receiving, from at least one of a first apparatus or a second apparatus, a request for switching to a target transmission mode of a sidelink reference signal; and means for transmitting, to at least one of the first apparatus or the second apparatus, an indication of the target transmission mode for sidelink positioning.

27. A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of any of claims 21-23.

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