Low-latency opportunistic channel occupancy time sharing

Abstract

An aspect relates to group-based reference signal broadcasting in a wireless communication network. A first wireless communication device may transmit a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. The first wireless communication device may receive a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device. The second positioning group may be associated with a channel occupation time (CoT) in a sidelink channel. The CoT may comprise transmission opportunities configured to be used by the second plurality of wireless communication devices to communicate reference signals. The first wireless communication device may initiate transmission of reference signals by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

Description

Technical Field

[0001]

[0001] The techniques described below generally relate to location estimation for wireless communication devices. More particularly, the techniques described relate to location estimation using sidelink communication.

Background Art

[0002]

[0002] Wireless communication between devices can be enabled in various configurations. In one configuration, a cellular network may enable user equipment (UE) to communicate with each other through signaling with nearby base stations or cells. In another configuration, such as a device-to-device (D2D) configuration, UEs may signal directly to each other without going through an intermediate base station or cell. For example, D2D communication may utilize sidelink signaling to enable direct communication between UEs. In some sidelink scenarios, UEs may further communicate in a cellular network, generally under the control of a base station. Thus, a UE may be configured for uplink and downlink signaling via a base station and further configured for direct sidelink signaling between UEs without transmission through a base station.

[0003]

[0003] An example of sidelink wireless communication is vehicle-to-everything (V2X) communication. V2X communication involves not only the exchange of information between vehicles themselves but also the exchange of information between vehicles and external systems such as streetlights, buildings, pedestrians, and cellular communication networks. A V2X system enables a vehicle to obtain information related to weather, nearby accidents, road conditions, activities of nearby vehicles and pedestrians, objects near the vehicle, and other relevant information that can be used to improve the vehicle driving experience, increase vehicle safety, and support autonomous vehicles. V2X communication is described here as just one example. Sidelink communication can involve other types of devices and communication interactions. For example, sidelink communication can be used in communication between smartphones (e.g., smartphone-to-smartphone), between industrial Internet of Things (IIoT) devices (e.g., IIoT-to-IIoT), and / or other types of communication.

[0004]

[0004] While the use of sidelink communication has many benefits, assuming the ability to communicate directly without an intermediate base station, the distributed nature of sidelink communication presents challenges in the management of signaling involving different entities.

Summary of the Invention

[0005]

[0005] The following presents an overview of one or more aspects of the present disclosure in order to provide a basic understanding of such aspects. This overview is not an exhaustive overview of all contemplated features of the present disclosure, nor does it identify the main or important elements of all aspects of the present disclosure, nor does it define the scope of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in the form of a prelude to the more detailed description presented later.

[0006]

[0006] In one example, a method of wireless communication in a first wireless communication device is disclosed. The method includes transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. The method further includes receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel. The CoT may comprise a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal. The method further includes starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0007]

[0007] Another example provides a first wireless communication device in a wireless communication network. The wireless communication device includes a wireless transceiver, a memory, and a processor communicatively coupled to the wireless transceiver and the memory. The processor is configured to transmit a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. The processor is configured to receive a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device. The second positioning group may be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT may comprise a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal. The processor is configured to start transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0008]

[0008] Another example provides a first wireless communication device in a wireless communication network. The wireless communication device includes means for transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. The wireless communication device further includes means for receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device. The second positioning group may be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT may comprise a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal. The wireless communication device further includes means for starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0009]

[0009] Another example provides a non-transitory computer-readable medium storing instructions for execution by one or more processing units. The non-transitory computer-readable medium comprises instructions for transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. The non-transitory computer-readable medium further comprises instructions for receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device. The second positioning group may be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT may comprise a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal. The non-transitory computer-readable medium further comprises instructions for starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0010]

[0010] These and other aspects will be more fully understood upon consideration of the following modes for carrying out the invention. By considering the following description of specific exemplary embodiments in conjunction with the accompanying drawings, other aspects, features, and embodiments will become apparent to those of ordinary skill in the art. Although features may be described in connection with some of the following embodiments and figures, all embodiments can include one or more of the advantageous features described herein. In other words, while one or more embodiments may be described as having certain advantageous features, one or more of such features can also be used in accordance with the various embodiments described herein. Similarly, while exemplary embodiments may be described below as embodiments of a device, system, or method, such exemplary embodiments can be implemented in various devices, systems, and methods.

[0011]

[0011] Aspects of the present disclosure are shown by way of example. In the accompanying drawings, like reference numerals indicate like elements.

Brief Description of the Drawings

[0012]

Figure 1

[0012] A diagram showing an example of a wireless access network according to some aspects.

Figure 2

[0013] A diagram showing an example of a wireless communication network employing sidelink communication according to some aspects.

Figure 3

[0014] A signaling diagram showing an example of sidelink-based positioning according to some aspects.

Figure 4

[0015] A diagram showing an example of transmission of positioning reference signals (PRS) in a sidelink communication network according to some aspects.

Figure 5

[0016] A signaling diagram showing an example of positioning group formation for group-based PRS broadcast according to some aspects.

Figure 6

[0017] A diagram showing an example of time domain allocation for positioning group formation and group-based PRS broadcast according to some aspects.

Figure 7

[0018] A diagram showing an example of a group formation broadcast message transmitted by a group initiator according to some aspects.

Figure 8

[0019] A diagram showing an example of a group formation broadcast message transmitted by a group responder according to some aspects.

Figure 9

[0020] A diagram showing an example of a group association broadcast message transmitted by a group initiator according to some aspects.

Figure 10

[0021] A diagram showing an example of positioning group formation according to some aspects.

Figure 11

[0022] A diagram showing an example of group-based PRS broadcast according to some aspects.

Figure 12

[0023] A diagram showing an example of the configuration of devices belonging to two PRS broadcast positioning groups in a scenario suitable for opportunistic CoT sharing.

Figure 13

[0024] A timing diagram showing an example of an opportunity for CoT sharing between two PRS broadcast positioning groups.

Figure 14

[0025] A diagram showing a successful attempt to opportunistically share CoT.

Figure 15

[0026] A diagram showing an unsuccessful attempt to opportunistically share CoT as a result of insufficient transmission time.

Figure 16

[0027] A diagram showing an unsuccessful attempt to opportunistically share CoT as a result of a failed clear channel assessment (CCA).

Figure 17

[0028] A block diagram showing an example of a hardware implementation form for a wireless communication device 1700 that employs a processing system.

Figure 18

[0029] A flowchart 1800 of an exemplary method for group-based PRS broadcast according to some embodiments.

Best Mode for Carrying Out the Invention

[0013]

[0030] Next, some exemplary embodiments with respect to the accompanying drawings, which form part of this application, will be described. Specific embodiments in which one or more aspects of the present disclosure can be implemented are described below, but other embodiments can be used and various changes can be made without departing from the scope of the present disclosure or the spirit of the appended claims.

[0014]

[0031] The embodiments for carrying out the invention described below with respect to the accompanying drawings are intended as descriptions of various configurations, and are not intended to represent only the configurations in which the concepts described herein can be practiced. The embodiments for carrying out the invention include specific details for providing a complete understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in the form of block diagrams to avoid obscuring such concepts.

[0015]

[0032] Aspects and embodiments are described in this application by way of examples of several cases, but those skilled in the art will understand that additional implementation forms and use cases can occur in many different configurations and scenarios. The innovations described herein can be implemented across many different platform types, devices, systems, shapes, sizes, and packaging configurations. For example, embodiments and / or uses can occur via integrated chip embodiments and other non-module component-based devices (such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / purchase devices, medical devices, AI-enabled devices, etc.). Some examples may or may not specifically target use cases or application examples, but a wide combination of the applicability of the described innovations can be made. Implementations can range from chip-level or modular components to non-modular non-chip-level implementations, and even to aggregates, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some actual settings, devices incorporating the described aspects and features may also necessarily include additional components and features for the implementation and practice of the claimed and described embodiments. For example, the transmission and reception of wireless signals necessarily include several components for analog and digital purposes (such as hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / subtractors, etc.). It is intended that the innovations described herein can be practiced in a wide variety of devices, chip-level components, systems, distributed configurations, end-user devices, etc. of different sizes, shapes, and structures.

[0016]

[0033] The various concepts presented throughout this disclosure can be implemented across a wide variety of telecommunications systems, network architectures, and communication standards. Turning now to FIG. 1, a schematic diagram of a radio access network 100 is provided by way of non-limiting illustrative example. The RAN 100 can implement one or more any suitable wireless communication technology to provide wireless access. As an example, the RAN 100 can operate in accordance with the 3rd Generation Partnership Project (3GPP (registered trademark)) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN 100 can operate under a hybrid of 5G NR and the evolved Universal Terrestrial Radio Access Network (eUTRAN) standard, often referred to as LTE (registered trademark). 3GPP refers to this hybrid RAN as the next generation RAN or NG-RAN. Of course, many other examples can be utilized within the scope of this disclosure.

[0017]

[0034] The geographic area covered by the radio access network 100 can be divided into several cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on identification information broadcast over a geographic area from one access point or base station. FIG. 1 shows macrocells 102, 104, and 106 and small cell 108, each of which can include one or more sectors (not shown). A sector is a sub-area of a cell. All sectors within one cell are served by the same base station. The wireless link within a sector can be identified by a single logical identification information belonging to that sector. In a cell divided into sectors, a plurality of sectors within the cell can be formed by a group of antennas, and each antenna is responsible for communicating with a UE in a portion of the cell.

[0018]

[0035] Generally, each base station (BS) serves each cell. Generally, a base station is a network element in a radio access network that is responsible for radio transmission and reception in one or more cells between the BS and a user equipment (UE). A BS may be referred to by those skilled in the art as a base transceiver station (BTS), radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), access point (AP), Node B (NB), eNode B (eNB), gNode B (gNB), or some other suitable term.

[0019]

[0036] In FIG. 1, two base stations 110 and 112 are shown in cells 102 and 104, and a third base station 114 that controls a remote radio head (RRH) 116 in cell 106 is shown. That is, a base station can have an integrated antenna or can be connected to an antenna or RRH by a feeder cable. In the illustrated example, cells 102, 104, and 106 may be referred to as macro cells because base stations 110, 112, and 114 support cells of relatively large size. Further, a base station 118 is shown in a small cell 108 (e.g., a micro cell, pico cell, femto cell, home base station, home Node B, home eNode B, etc.), and small cell 108 may overlap one or more macro cells. In this example, cell 108 may be referred to as a small cell because base station 118 supports a cell of relatively small size. Cell sizing can be performed according to system design as well as component constraints. It should be understood that radio access network 100 may include any number of wireless base stations and cells. Further, relay nodes may be deployed to extend the size or coverage area of a given cell. Base stations 110, 112, 114, 118 provide a wireless access point to a core network for any number of mobile devices.

[0020]

[0037] FIG. 1 further includes a quadcopter or drone 120 configured to function as a base station. That is, in some examples, the cell may not necessarily be fixed, and the geographical area of the cell may move according to the location of a mobile base station such as the quadcopter 120.

[0021]

[0038] Generally, a base station may include a backhaul interface for communicating with a backhaul portion (not shown) of the network. The backhaul may provide a link between the base station and a core network (not shown), and in some examples, the backhaul may provide an interconnection between respective base stations. The core network may be part of a wireless communication system and may be independent of the radio access technology used in the radio access network. Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, using any suitable transport network.

[0022]

[0039] RAN 100 is shown to support wireless communication for a plurality of mobile devices. Mobile devices are generally referred to as user equipment (UE) in the standards and specifications published by the Third Generation Partnership Project (3GPP), but may also be referred to by those skilled in the art as a mobile station (MS), subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal (AT), mobile terminal, wireless terminal, remote terminal, handset, terminal, user agent, mobile client, client, or some other suitable term. The UE may be a device that provides a user with access to network services.

[0023]

[0040] In this document, a "mobile" device does not necessarily need to have the ability to move and can be stationary. The term mobile device or mobile unit broadly refers to a wide variety of devices and technologies. For example, some non-limiting examples of mobile devices include mobile, cellular (cell) phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal computers (PCs), notebooks, netbooks, smartbooks, tablets, personal digital assistants (PDAs), and a wide variety of embedded systems, such as those corresponding to the "Internet of Things" (IoT). Mobile devices can further include automobiles or other transportation vehicles, remote sensors or actuators, robots or robotics devices, satellite radios, global positioning system (GPS) devices, object tracking devices, drones, multicopters, quadcopters, remote control devices, eyewear, wearable cameras, virtual reality devices, smartwatches, health trackers or fitness trackers, digital audio players (e.g., MP3 players), cameras, game consoles, and other consumer devices and / or wearable devices. Mobile devices can further include digital home or smart home devices, such as home audio, video, and / or multimedia devices, appliances, vending machines, intelligent lighting, home security systems, smart meters, etc. Mobile devices can further include smart energy devices, security devices, solar panels or solar arrays, urban infrastructure devices that control power (e.g., smart grid), lighting, water, etc., industrial automation and / or enterprise devices, logistics controllers, agricultural equipment, etc. Still further, mobile devices can enable connected medical or telemedicine support, i.e., remote healthcare.A telehealth device may include a telehealth monitoring device and a telehealth administration device, and their communications may be given preferential treatment or priority access over other types of information, for example, for priority access for transferring critical service data and / or for related QoS for transferring critical service data.

[0024]

[0041] Within RAN100, a cell may include UEs that may be communicating with one or more sectors of each cell. For example, UEs 122 and 124 may communicate with base station 110, UEs 126 and 128 may communicate with base station 112, UEs 130 and 132 may communicate with base station 114 via RRH116, UE 134 may communicate with base station 118, and UE 136 may communicate with mobile base station 120. Here, each of base stations 110, 112, 114, 118, and 120 may be configured to provide an access point to a core network (not shown) for all UEs in their respective cells. In another example, a mobile network node (e.g., quadcopter 120) may be configured to function as a UE. For example, quadcopter 120 may operate within cell 102 by communicating with base station 110.

[0025]

[0042] Wireless communication between RAN 100 and a UE (e.g., UE 122 or 124) can be described as utilizing an air interface. Transmission via the air interface from a base station (e.g., base station 110) to one or more UEs (e.g., UEs 122 and 124) may be referred to as downlink (DL) transmission. According to some aspects of the present disclosure, the term downlink may refer to point-to-multipoint transmission originating at a scheduling entity (e.g., base station 110, further described below). Another way to describe this approach may be to use the term broadcast channel multiplexing. Transmission from a UE (e.g., UE 122) to a base station (e.g., base station 110) may be referred to as uplink (UL) transmission. According to further aspects of the present disclosure, the term uplink may refer to point-to-point transmission originating at a scheduled entity (e.g., UE 122, further described below).

[0026]

[0043] For example, DL transmission may include unicast or broadcast transmission of control information and / or traffic information (e.g., user data traffic) from a base station (e.g., base station 110) to one or more UEs (e.g., UEs 122 and 124), and UL transmission may include transmission of control information and / or traffic information transmitted by a UE (e.g., UE 122). Further, uplink and / or downlink control information and / or traffic information may be time-division multiplexed in frames, subframes, slots, and / or symbols. As used herein, a symbol may refer to a time unit that carries one resource element (RE) per subcarrier in an orthogonal frequency division multiplexing (OFDM) waveform. A slot may carry 7 or 14 OFDM symbols. A subframe may refer to a duration of 1 ms. A plurality of subframes or slots may be grouped together to form a single frame or radio frame. Of course, these definitions are not required, and any suitable manner for organizing the waveform may be utilized, and various time divisions of the waveform may have any suitable duration.

[0027]

[0044] The air interface in RAN100 may utilize one or more multiplexings and multiple access algorithms to enable simultaneous communication of various devices. For example, the 5G NR specification utilizes orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) to provide multiplexing for UL or reverse link transmissions from UEs 122 and 124 to base station 110 and for DL or forward link transmissions from base station 110 to UEs 122 and 124. Further, for UL transmissions, the 5G NR specification provides support for discrete Fourier transform-spread OFDM (DFT-s-OFDM: also called single carrier FDMA (SC-FDMA)) with CP. However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above-described methods and may be provided using time division multiple access (TDMA), code division multiple access (CDMA), frequency division multiple access (FDMA), sparse code multiple access (SCMA), resource spread multiple access (RSMA), or other suitable multiple access methods. Further, multiplexing DL transmissions from base station 110 to UEs 122 and 124 may be provided using time division multiplexing (TDM), code division multiplexing (CDM), frequency division multiplexing (FDM), orthogonal frequency division multiplexing (OFDM), sparse code multiplexing (SCM), or other suitable multiplexing methods.

[0028]

[0045] Furthermore, the air interface in RAN100 may utilize one or more duplexing algorithms. Duplex refers to a point-to-point communication link where both endpoints can communicate with each other in both directions. Full duplex means that both endpoints can communicate with each other simultaneously. Half duplex means that only one endpoint can send information to the other endpoint at a time. In a wireless link, a full-duplex channel generally relies on physical separation of the transmitter and receiver and suitable interference cancellation techniques. Full-duplex emulation is frequently implemented for wireless links by utilizing frequency division duplexing (FDD) or time division duplexing (TDD). In FDD, transmissions in different directions operate at different carrier frequencies. In TDD, transmissions in different directions on a given channel are separated from each other using time division multiplexing. That is, at a certain time, the channel is dedicated to transmission in one direction, and at other times, the channel is dedicated to transmission in the other direction, where the direction can change very rapidly, for example, several times per slot.

[0029]

[0046] In RAN100, the ability of a UE to communicate while moving regardless of its location is called mobility. The various physical channels between the UE and the RAN are generally set up, maintained, and released under the control of an access and mobility management function (AMF, not shown) in the core network coupled to RAN100. In some scenarios, the AMF may include a security context management function (SCMF) and a security anchor function (SEAF). The SCMF can manage security contexts for both the control plane function and the user plane function, either wholly or in part. The SEAF can perform authentication.

[0030]

[0047] In some examples, RAN 100 may enable mobility and handover (i.e., transfer of a UE's connection from one radio channel to another radio channel). For example, during a call with a scheduling entity or at any other time, the UE may monitor various parameters of signals from its serving cell as well as various parameters of neighboring cells. Depending on the quality of these parameters, the UE may maintain communication with one or more of the neighboring cells. During this time, if the UE moves from one cell to another or if the signal quality from a neighboring cell exceeds the signal quality from the serving cell for a given amount of time, the UE may initiate a handoff or handover from the serving cell to the neighboring (target) cell. For example, (although any suitable form of UE may be used, shown as a vehicle) UE 124 may move from the geographic area corresponding to its serving cell 102 to the geographic area corresponding to neighbor cell 106. When the signal strength or signal quality from neighbor cell 106 exceeds the signal strength or signal quality of UE 124's serving cell 102 for a given amount of time, UE 124 may send a report message indicating this condition to its serving base station 110. In response, UE 124 may receive a handover command and the UE may undergo a handover to cell 106.

[0031]

[0048] In various implementations, the air interface in RAN100 may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum generally enables exclusive use of a portion of the spectrum by a mobile network operator purchasing a license from a government regulatory agency. Unlicensed spectrum enables shared use of a portion of the spectrum without the need for a government permission license. While some technical rules compliance is generally still required to access unlicensed spectrum, generally any operator or device may acquire access. An example of unlicensed spectrum includes the dedicated short range communications (DSRC) band in the 5.9 GHz frequency band. Shared spectrum may lie between licensed and unlicensed spectrum and may require technical rules or limitations to access the spectrum, but the spectrum may still be shared by multiple operators and / or multiple RATs. For example, a license holder for a portion of licensed spectrum may provide licensed shared access (LSA) to share that spectrum with other parties, for example, using suitable licensee determination conditions to acquire access.

[0032]

[0049] In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., a base station) allocates resources (e.g., time-frequency resources) for communication between some or all of the devices and apparatuses within its service area or cell. Within the present disclosure, as further described below, the scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more scheduled entities. That is, in scheduled communication, the UE or scheduled entity utilizes resources allocated by the scheduling entity.

[0033]

[0050] The base station is not the only entity that can function as a scheduling entity. That is, in some examples, a UE can function as a scheduling entity and schedule resources for one or more scheduled entities (e.g., one or more other UEs). In other examples, sidelink signals can be used between UEs without necessarily relying on scheduling or control information from the base station. For example, UE 138 communicating with UEs 140 and 142 is shown. In some examples, UE 138 functions as a scheduling entity or a transmitting sidelink device, and UEs 140 and 142 can function as scheduled entities or receiving sidelink devices. For example, UE 138 can function as a scheduling entity in device-to-device (D2D), peer-to-peer (P2P), vehicle-to-everything (V2X), and / or a mesh network. In an example of a mesh network, in addition to communicating with the scheduling entity 138, UEs 140 and 142 can optionally communicate directly with each other.

[0034]

[0051] In some aspects of the present disclosure, two or more UEs (e.g., UEs 126 and 128) within the coverage area of the serving base station 112 can communicate with each other using sidelink signals 127 without relaying their communication through the base station. In this example, the base station 127 or one or both of UEs 126 and 128 can function as a scheduling entity to schedule sidelink communication between UE 126 and UE 128. For example, UEs 126 and 128 can communicate sidelink signals 127 within a vehicle-to-everything (V2X) network.

[0035]

[0052] Two main technologies that can be used by V2X networks include dedicated short range communication (DSRC) based on the IEEE802.11p standard and cellular V2X based on the LTE standard and / or 5G (New Radio) standard. Various aspects of the present disclosure may relate to a New Radio (NR) cellular V2X network, referred to herein as a V2X network for simplicity. However, it should be understood that the concepts disclosed herein may not be limited to a particular V2X standard or may be applicable to sidelink or D2D networks other than V2X networks.

[0036]

[0053] FIG. 2 shows an example of a wireless communication network 200 configured to support D2D or sidelink communication. In some examples, sidelink communication may include V2X communication. V2X communication involves not only the direct wireless exchange of information between vehicles themselves (e.g., vehicles 202 and 204), but also the direct wireless exchange of information between vehicles 202 / 204 and infrastructure 206 (e.g., roadside units (RSUs)) such as streetlights, buildings, traffic cameras, toll booths, or other fixed objects, between vehicles 202 / 204 and pedestrians 208, and between vehicles 202 / 204 and a cellular network (e.g., base station 210). In some examples, V2X communication may be implemented in accordance with the New Radio (NR) cellular V2X standard defined by 3GPP, Release 15 or 16, or other suitable standards.

[0037]

[0054] V2X communication enables vehicles 202 and 204 to obtain information related to weather, nearby accidents, road conditions, activities of nearby vehicles and pedestrians, objects near the vehicle, and other related information that can be used to improve the vehicle driving experience and increase vehicle safety. For example, such V2X data can enable autonomous driving and improve road safety and traffic efficiency. For example, the exchanged V2X data can be used by V2X-connected vehicles 202 and 204 to provide in-vehicle collision warnings, road hazard warnings, emergency vehicle approach warnings, pre / post-crash warnings and information, emergency brake warnings, forward traffic jam warnings, lane change warnings, intelligent navigation services, and other similar information. Further, the V2X data received by the V2X-connected mobile device of pedestrian / cyclist 208 can be used to trigger warning sounds, vibrations, flashing lights, etc. in case of imminent danger.

[0038]

[0055] The sidelink communication between vehicle UEs (V-UEs) 202 and 204, or between a V-UE 202 or 204 and either an RSU 206 or a pedestrian UE (P-UE) 208, is performed over a sidelink channel 212. The sidelink channel 212 can be used to establish a PC5 interface, with or without a wireless network including a base station (e.g., base station 210). In cases where a wireless network is involved, the PC5 interface can be directed by the wireless network. For example, the wireless network can direct the PC5 interface over the Uu radio interface established between a UE (e.g., V-UEs 202, 204, P-UE 208, etc.) and a radio access network (RAN) of the wireless network, e.g., base station 210. In some examples, the sidelink channel 212 can support a ProSe PC5 interface. In various aspects of the present disclosure, the sidelink channel 212 implementing the PC5 interface can be further utilized to support D2D communication in other proximity use cases. Examples of other proximity use cases can include public safety or commercial (e.g., entertainment, education, office, medical, and / or interactive) based proximity services.

[0039]

[0056] ProSe communication can support different operation scenarios, such as in-coverage, out-of-coverage, and partial-coverage. Out-of-coverage refers to a scenario where UEs (e.g., V-UE202 and 204 and P-UE208) are outside the coverage area of a base station (e.g., base station 210), but each is still configured for ProSe communication. Partial-coverage refers to a scenario where some of the UEs (e.g., V-UE204) are outside the coverage area of base station 210, and other UEs (e.g., V-UE202 and P-UE208) are communicating with base station 210. In-coverage refers to a scenario where UEs (e.g., UE214 and 216) are communicating with a base station 210 (e.g., gNB) via a Uu (e.g., cellular interface) connection to receive ProSe service authorization and provisioning information for supporting ProSe operation.

[0040]

[0057] In any of the above operation scenarios, various mobile side-link devices (e.g., V-UE202 and 204, P-UE208, and other mobile side-link devices communicating on side-link channel 212) can determine their locations (e.g., geographical coordinates) in side-link network 200 using a side-link positioning mechanism. To support side-link positioning, positioning reference signals (PRS) can be transmitted between RSU206 and V-UE202 and 204 and P-UE208. In some examples, the PRS can be a sequence-based signal and can be further transmitted on unlicensed spectrum (e.g., ITS band) or licensed spectrum.

[0041]

[0058] Depending on the capabilities of the mobile sidelink devices (e.g., V-UE202 / 204 and P-UE208), the respective locations of each mobile sidelink device can be determined using sidelink-based (SL-b) positioning or sidelink-assisted (SL-a) positioning. In SL-b positioning, each mobile sidelink device calculates its own location in a distributed manner using broadcast PRS. In SL-a positioning, the RSU206 or other servers in the network calculate the location of the mobile sidelink device. In either SL-a or SL-b positioning, the location of a mobile sidelink device (e.g., V-UE202) can be determined based on the round-trip time (RTT) between the mobile sidelink device (e.g., V-UE202) and another sidelink device (e.g., RSU206). Such RTT measurements indicate the distance between the two devices. In some such RTT measurements (and corresponding distances), multilateration can be used to determine the location of the mobile sidelink device. For example, V-UE202 can obtain three RTT measurements made with three different RSUs. The first RTT measurement can indicate the distance between V-UE202 and the first RSU. The second RTT measurement can indicate the distance between V-UE202 and the second RSU. The third RTT measurement can indicate the distance between V-UE202 and the third RSU. If the locations of the three RSUs are known, the location of V-UE202 can be determined by multilateration, for example, using the three distances as the radii of circles centered on the known RSU locations.

[0042]

[0059] FIG. 3 is a signaling diagram showing an example of sidelink-based (SL-b) positioning according to some aspects. In the example shown in FIG. 3, a V-UE 304 that communicates with an RSU 302 over a sidelink channel is shown. In some examples, the sidelink channel may include an unlicensed spectrum (e.g., the ITS frequency band). The V-UE 304 may correspond to, for example, either the V-UE 202 or 204 shown in FIG. 2. Further, the RSU 302 may correspond to, for example, the RSU 206 shown in FIG. 2. It should be understood that the signaling diagram shown in FIG. 3 may be implemented between any two wireless communication devices (e.g., RSU, V-UE, P-UE, etc.), and further may be implemented between three or more wireless communication devices (e.g., between the V-UE 304 and multiple RSU 302s, between one or more RSUs and one or more P-UEs or V-UEs, and / or between a V-UE and two or more other V-UEs or P-UEs).

[0043]

[0060] Figure 3 shows one RTT measurement. The RTT measurement involves the exchange of PRS signal 306 and PRS signal 308. PRS signal 306 represents the propagation of a signal in one direction from RSU 302 to V-UE 304. PRS signal 308 represents the propagation of a signal in the opposite direction from V-UE 304 to RSU 302, thus completing the round trip. In the example shown in Figure 3, time is shown vertically to indicate the transmission and reception of signals over time. For example, at 306, RSU 302 broadcasts a first PRS on the sidelink channel at an initial time (t1). The first PRS may include, for example, a PRS sequence. The PRS sequence may be a broadband random sequence broadcast on an unlicensed frequency band. In some examples, the PRS may include a sequence identifier (ID) that identifies the PRS sequence. The first PRS may be received at V-UE 304 at a second time (t2) after t1. At 308, V-UE 304 broadcasts a second PRS on the sidelink channel at a third time (t3), and the second PRS is received at RSU 302 at a fourth time (t4). Thus, the RTT measurement comprises a first propagation time (t2 - t1) and a second propagation time (t4 - t3). That is, RTT = (t2 - t1) + (t4 - t3), which can be reconfigured as RTT = (t4 - t1) - (t3 - t2). V-UE 304 can locally determine the time difference (t3 - t2). RSU 302 can locally determine the time difference (t4 - t1). These two time differences can be combined at RSU 302, at V-UE 304, or at another location to calculate the RTT.

[0044]

[0061] For example, when the RTT is to be calculated at the V-UE304 (e.g., SL-b positioning), the V-UE304 may locally determine the time difference (t3 - t2) and receive from the RSU302 a PRS message 310 that includes the time difference (t4 - t1) as a payload. The PRS message may also include other information. As shown in FIG. 3, the RSU302 transmits to the V-UE304 a PRS measurement message including various positioning information on the sidelink channel. For example, the positioning information included in the payload of the PRS measurement message may include the departure time (t1) of the first PRS and the arrival time (t4) of the second PRS (either individually as t1 and t4 or as the time difference (t4 - t1)). Other positioning information may include the PRS sequence ID, the clock error noise standard deviation of the RSU302, the clock drift standard deviation of the RSU302, the location of the RSU302, and other suitable information. The PRS measurement message may further include the respective UE IDs of the RSU302 and the V-UE304 (e.g., layer 2 (L2) media access control (MAC) IDs).

[0045]

[0062] Accordingly, at 312, the V-UE304 may calculate the RTT based on the positioning information included in the PRS measurement message, the arrival time (t2) of the first PRS, the departure time (t3) of the second PRS, and the clock error of the V-UE304 (e.g., the clock drift standard deviation and the clock error noise standard deviation) determined using its own Kalman filter. For example, when multiple RTT measurements are made, the nth RTT may be expressed as follows.

[0046]

Number

[0047] Here, v light is the speed of light, α is an adjustment parameter based on the clock errors of the RSU302 and the V-UE304, r is the location of the RSU302, and x is unknown.

[0048]

[0063] In an example where SL-a positioning is used, the V-UE 304 can send a PRS measurement message to the RSU 302 that includes other positioning information such as, for example, the arrival time (t2) of the first PRS, the departure time (t3) of the second PRS, as well as the clock error of the V-UE 304, the speed of the V-UE 304, and the location of the V-UE 304 at the time of the PRS broadcast (if known).

[0049]

[0064] Positioning reference signals (PRSs) are used as an example to illustrate various aspects, but different types of reference signals can be used. For example, sounding reference signals (SRSs) can be used instead. Generally, SRSs are transmitted by user equipment (UE) in the uplink direction and are used by the eNodeB to estimate uplink channel quality over a wider bandwidth. The eNodeB can use the channel quality information for uplink frequency-selective scheduling. SRSs are just one alternative. Other types of reference signals can be used instead of the PRSs referred to herein.

[0050]

[0065] FIG. 4 is a diagram illustrating an example of the transmission of a positioning reference signal (PRS) in a sidelink communication network 400 according to some aspects. In the example shown in FIG. 4, a V-UE 402 that is wirelessly communicating with a plurality of RSU 404, 406, and 408 over a sidelink channel is shown. In some examples, the sidelink channel can include unlicensed spectrum (e.g., the ITS frequency band). The V-UE 402 can correspond to, for example, any of the V-UEs shown in FIGS. 2 and / or 3. Further, the RSU 404, 406, and 408 can correspond to, for example, any of the RSU shown in FIGS. 2 and / or 3. It should be further understood that in some examples, the V-UE 402 can be a P-UE or other mobile sidelink device. Further, one or more of the RSU 404, 406, and 408 can be other V-UEs, P-UEs, and / or other mobile sidelink devices.

[0051]

[0066] Figure 4 further shows the PRS communication between V-UE 402 and RSU 404, 406, and 408 over time. For example, a first PRS 410 (shown as signal 1) is broadcast from RSU 404, followed by a second PRS 412 (shown as signal 2) broadcast from RSU 406, followed by a third PRS 414 (shown as signal 3) broadcast by RSU 408, and then a fourth PRS 416 (shown as signal 4) may be broadcast by V-UE 402. Upon receipt of the fourth PRS 416 by each of RSU 404, 406, and 408, each of RSU 404, 406, and 408 may then transmit respective PRS measurement signals 418, 420, and 422 (shown as signals 5, 6, and 7) to V-UE 402. V-UE 402 may then calculate its location based on the PRS measurement signals 418, 420, and 422, the departure time of the fourth PRS 416, and the respective arrival times in V-UE 402 of the other PRS 410, 412, and 414, as described above. For example, PRS 410 and PRS 416 (shown as signals 1 and 4) may constitute a first RTT measurement together with the PRS measurement signal 418 (shown as signal 5). PRS 412 and PRS 416 (shown as signals 2 and 4) may constitute a second RTT measurement together with the PRS measurement signal 420 (shown as signal 6). PRS 414 and PRS 416 (shown as signals 3 and 4) may constitute a third RTT measurement together with the PRS measurement signal 422 (shown as signal 7). Upon obtaining three RTT measurements, V-UE 402 may determine its own location by performing trilateration using the known locations of RSU 404, 406, and 408.

[0052]

[0067] The efficiency and accuracy of SL-b positioning (or SL-a positioning) depend on the latency (e.g., time gap 424) between PRS410, 412, 414, and 416. When implementing Listen Before Talk (LBT) or another channel sensing mechanism to access the sidelink channel, the availability of the sidelink channel for each wireless communication device (e.g., V-UE402, RSU404, RSU406, and RSU408) varies and can thus affect the PRS latency.

[0053]

[0068] Thus, in various aspects of the present disclosure, wireless communication devices (e.g., V-UE, P-UE, RSU, etc.) communicating on a sidelink channel in a sidelink wireless communication network can be grouped into one or more positioning groups. Within each positioning group, the respective order of the wireless communication devices in the positioning group can be identified. Wireless communication devices (e.g., positioning group members) in a particular positioning group can then communicate PRS among themselves on the sidelink channel based on the determined order of the wireless communication devices. For example, the sidelink channel can be reserved for a Channel Occupancy Time (CoT) during which each of the wireless communication devices in the positioning group can broadcast PRS in the positioning group and communicate PRS measurement messages to other positioning group members, thus reducing the PRS latency.

[0054]

[0069] In some examples, a wireless communication device may be configured to form a positioning group by broadcasting a group formation broadcast message on a sidelink channel. One of the wireless communication devices in each positioning group may be regarded as a starting device that starts the positioning group, and the other wireless communication devices in the positioning group may be regarded as responding devices. For example, the starting device may broadcast a starting (or first) group formation broadcast message to form a positioning group. Other wireless communication devices that receive the starting group formation broadcast message may then respond with a subsequent responding device group formation broadcast message that identifies the starting device and other responding devices that previously responded to the first group formation broadcast message. Thus, the responding device group formation broadcast messages may depend on each other such that the last responding device group formation broadcast message identifies both the starting device and all of the other responding devices in the positioning group.

[0055]

[0070] The starting device may then determine the order of the wireless communication devices in the positioning group from each of the responding device group formation broadcast messages and transmit (e.g., broadcast or multicast) a group association broadcast message that identifies the members of the positioning group and their order. The starting device may then reserve a sidelink channel for CoT based on the number of wireless communication devices in the positioning group and broadcast a first PRS during the CoT. The responding devices may then each broadcast their respective PRSs within the CoT based on the order of the wireless communication devices. Thus, the respective transmission timings of each of the PRSs from each of the wireless communication devices in the positioning group may be determined from that order.

[0056]

[0071] As described, messages such as group formation messages (GFMs) or group association messages (GAMs) can be sent in the form of broadcast messages. Such broadcast messages can be "broadcast" or "groupcast" to various devices. In this sense, "broadcasting" refers to transmission to two or more devices. All devices within the signal range of the broadcast may be able to receive the message. In contrast, "groupcasting" refers to reception only by a subset of the devices within the signal range. For example, a signal associated with a groupcast message may reach a set of devices ("A"). However, the groupcast may target only a subset of the devices ("B") within the set of devices "A" and can only be decoded thereby.

[0057]

[0072] In some examples, LBT can be used to reserve a sidelink channel. For example, a starting device (e.g., an RSU, a V-UE, a P-UE, etc.) can perform an LBT procedure to determine whether it can reserve a sidelink channel. In some aspects, the LBT procedure can involve sensing energy on the channel and comparing that energy to an energy detection (ED) threshold. For example, if the detected energy on the channel is at or below the ED threshold level (e.g., indicating that the channel is relatively traffic-free), the starting device can reserve a sidelink channel for CoT and transmit a first PRS.

[0058]

[0073] Different types of LBT procedures can be defined according to different categories. For example, Category 1 (Cat.1) LBT specifies that LBT is not used. Cat.2 LBT specifies the use of LBT without random backoff. Cat.3 LBT specifies the use of LBT with random backoff with a fixed-size contention window. Cat.4 LBT specifies the use of LBT with random backoff with a variable-size contention window. In one aspect, the initiating device may implement Cat4 LBT to reserve CoT for all positioning group members. Thereafter, the responding device may implement Cat2 LBT to broadcast their PRS.

[0059]

[0074] In some examples, wireless communication devices in a sidelink communication network can be categorized as either an anchor device or a non-anchor device. Anchor devices can include, for example, RSU (e.g., RSU404, 406, and 408) along with V-UE (e.g., V-UE402) and P-UE that include an accurate internal positioning device (e.g., GPS or other navigation system). Non-anchor devices can include, for example, V-UE and P-UE that do not include an accurate internal positioning device. Thus, an anchor device can be considered to have a known location based on location accuracy (e.g., an acceptable accuracy tolerance or deviation), and a non-anchor device can be considered to have an unknown location based on location accuracy.

[0060]

[0075] In some aspects, the initiating device may include an anchor device, and the responding device may include at least a non-anchor device. In some examples, an anchor device that receives a group formation broadcast message from another anchor initiating device may become either a responding device for that initiating device or an initiating device for another positioning group. For example, the anchor device may compare the reference signal received power (RSRP) of the group formation broadcast message received from another anchor initiating device to determine whether to become a responding device for another initiating device. As an example, if the RSRP of the received group formation broadcast message is greater than or equal to a threshold (threshold power), the anchor device may become a responding device. Otherwise, if the RSRP of the received group formation broadcast message is less than the threshold, the anchor device may become an initiating device for another positioning group. In this example, the other anchor initiating device may be excluded from the positioning group (e.g., the other anchor initiating device may form its own separate positioning group).

[0061]

[0076] Similarly, in the responder device, when a plurality of group formation broadcast messages are received from a plurality of anchor initiating devices, the responder device selects one of the anchor initiating devices and can join the positioning group of the selected anchor initiating device (e.g., by sending a responder group formation broadcast message including the selected anchor initiating device ID). In some examples, each positioning group can be composed of a maximum number of members. When the maximum number of members is reached for one of the positioning groups, the responder device can select another positioning group or become an initiating side if no other positioning groups are available. In some examples, non-anchor devices may not receive group formation broadcast messages from anchor initiating devices. In this example, the non-anchor device can become an initiating device to start a positioning group for non-anchor devices.

[0077] In some examples, positioning group formation can be performed periodically. For example, the group formation broadcast message associated with the new positioning group can be broadcast at a periodicity smaller than (e.g., having a longer duration than) the periodicity of the PRS cycle to allow the positioning group to complete a plurality of PRS cycles before changing the positioning group. In some examples, the PRS cycle can be 100 ms. In this example, positioning group formation can be performed every 1000 ms.

[0062]

[0078] For example, the positioning group formation can be performed in the group phase in the time domain. After the group phase, a PRS phase including one or more PRS cycles may follow. The group phase may further include a start-side sub-phase and a response-side sub-phase. The anchor device may transmit a start-side group formation broadcast message within the start-side sub-phase. The response-side device may transmit a response-side group formation broadcast message within the response-side sub-phase. Further, a non-anchor device that did not receive the start-side group formation broadcast message within the start-side sub-phase may transmit the start-side group formation broadcast message within the response-side sub-phase. The group phase may further include a second start-side sub-phase after the response-side sub-phase, in which the start-side device may transmit a group association broadcast message for identifying the members of the positioning group and their order.

[0063]

[0079] FIG. 5 is a signaling diagram showing an example of positioning group formation for group-based PRS broadcast according to some aspects. In the example shown in FIG. 5, a start-side wireless communication device (WCD1) 502 is wirelessly communicating with response-side wireless communication devices 504 and 506 (WCD2 and WCD3, respectively) on a sidelink channel. In some examples, the sidelink channel may include an unlicensed spectrum (e.g., ITS spectrum). In other examples, the sidelink channel may include a licensed spectrum. The sidelink channel may utilize LBT or another channel sensing mechanism for channel access.

[0064]

[0080] Each of the wireless communication devices 502, 504, and 506 may correspond to any of the RSU, V-UE, or P-UE shown in FIGS. 2, 3, and / or 4. In some examples, the initiating wireless communication device 502 (referred to herein as the initiating device for simplicity) may be an anchor device. In other examples, the initiating device 502 may be a non-anchor device in the example where the group formation broadcast message is not received from the anchor device. The responding wireless communication devices 504 and 506 (referred to herein as the responding devices for simplicity) may be non-anchor devices or anchor devices (e.g., when the initiating device 502 is in very close proximity to the anchor device).

[0065]

[0081] At 508, the initiating device 502 may broadcast (or group-cast) a first group formation broadcast message on the sidelink channel to form a positioning group. At 510, the responding device 504 may broadcast (or group-cast) a second group formation broadcast message on the sidelink channel to join the positioning group. The second group formation broadcast message may include, for example, the initiating ID of the initiating device. At 512, the responding device 506 may broadcast (or group-cast) a third group formation broadcast message on the sidelink channel to join the positioning group. The third group formation may include, for example, the initiating ID of the initiating device and the responding ID of the responding device 504. Each of the first, second, and third group formation messages may further include other device information associated with the transmitting device. Examples of device information may include, but are not limited to, initiating side information indicating whether the transmitting device is the initiating device of the positioning group, anchor information indicating whether the transmitting device is an anchor device or a non-anchor device, power information indicating whether the transmitting device is power-limited (e.g., operating in an intermittent reception mode), and a group ID identifying the transmitting device within the positioning group. In some examples, the group ID may be a random number within the group. In other examples, the group ID may be the UE ID (e.g., MAC ID) of the transmitting device.

[0066]

[0082] At 514, the initiating device 502 may determine the order of the wireless communication devices 502, 504, and 506 within the positioning group. For example, upon receiving each of the second and third group formation messages, the initiating device 502 may include the responder devices 504 and 506 within the positioning group. The initiating device 502 may then be listed first in the order of the wireless communication devices, followed by the other responder devices 504 and 506. Various factors may be used by the initiating device 502 to determine the order of the responder devices 504 and 506. For example, the order of the responder devices 504 and 506 may be determined based on the device information included within the group formation messages. In one example, the order may correspond to the descending order of the responder devices.

[0067]

[0083] At 516, the initiating device 502 may broadcast or multicast a group association broadcast message to the responder devices 504 and 506. The group association message may include the initiating ID of the initiating device, listed in the order of the wireless communication devices (e.g., descending order), and the respective responder IDs of each of the responder devices 504 and 506.

[0068]

[0084] At 518, 520, and 522, the initiating device 502 and the responder devices 504 and 506 can each broadcast (or group-cast) their respective PRSs based on the order of the wireless communication devices listed in the group association message. For example, the initiating device 502 can broadcast (or group-cast) a first PRS at 518. Then, at 520, the responder device 504 can broadcast (or group-cast) a second PRS. Then, at 522, the responder device 506 can broadcast a third PRS. In some examples, the initiating device 502 can implement Cat4 LBT to reserve a sidelink channel for a CoT for which all of the PRSs (and corresponding PRS measurement messages) can be transmitted. Thereafter, the responder devices 504 and 506 can implement Cat2 LBT to broadcast their PRSs.

[0069]

[0085] As described above, positioning reference signals (PRSs) are used as an example to illustrate various aspects, but different types of reference signals, such as sounding reference signals (SRSs) or other types of signals, can be used instead.

[0070]

[0086] FIG. 6 is a diagram illustrating an example of time domain allocation for positioning group formation and group-based PRS broadcast according to some aspects. In the example shown in FIG. 6, the sidelink channel can be time-division multiplexed into a group phase (for simplicity, two of them 602a and 602b are shown) and a PRS phase (for simplicity, one of them 604 is shown). The PRS phase 604 includes one or more PRS cycles. Each PRS cycle includes group-based PRS broadcast by one or more positioning groups. For example, within a PRS cycle, wireless communication devices within each positioning group can broadcast their PRS (and corresponding PRS measurement messages) within their respective CoTs reserved by their respective starting devices. In some examples, the periodicity of the group phases 602a and 602b is smaller than the periodicity of the PRS cycle. For example, the PRS cycle can be 100 ms, and the periodicity of the group phases 602a and 602b can be 1000 ms. Thus, 10 PRS cycles can occur between the group phase 602a and the group phase 602b.

[0071]

[0087] Each of the group phases 602a and 602b can be further time-division multiplexed into a first starting-side sub-phase 606, a response-side sub-phase 608, and a second starting-side sub-phase 610. Within the first starting-side sub-phase 606, an anchor device can transmit a starting-side group formation message to start a positioning group. Within the response-side sub-phase 608, response-side devices (e.g., non-anchor devices and anchor devices within very close proximity to another anchor device that broadcast a starting-side group formation message in the starting-side sub-phase 606) can broadcast a response-side group formation message. Within the second starting-side sub-phase 610, the starting-side devices can broadcast or multicast a group association message that identifies the members of their respective positioning groups and the respective PRS broadcast order of the members within their respective positioning groups.

[0072]

[0088] In the example shown in FIG. 6, the anchor device may broadcast (or group-cast) its start-side group formation message at time Unif(X+0,X+T1), where T1 is the time budget for the anchor device to broadcast those group formation messages. In some examples, T1 = 100 ms. Here, X refers to the periodicity of group phases 602a and 602b (e.g., X = 0 ms, 1,000 ms, 2,000 ms, 3,000 ms,...). In some examples, each subsequent group phase (e.g., group phase 602b) may start after a time gap (X+T_g) from the end of the PRS phase 604 to minimize interference on the sidelink channel. Similarly, the responder device may broadcast its responder-side group formation message at time Unif(X+T1,X+T2), where T2 is the time budget for the responder device to broadcast those group formation messages. In some examples, T2 ≧ 100 ms. Then, each start-side device may broadcast its group association message at time Unif(X+T2,X+T3), where T3 is the time budget for the start-side device to broadcast those group association messages. In some examples, T3 ≧ 100 ms.

[0073]

[0089] FIG. 7 is a diagram showing an example of a group formation broadcast message 700 that can be transmitted by a group start side according to some embodiments. The payload of the group formation broadcast message 700 includes a plurality of basic fields 702 that carry device information. The group formation broadcast message may further include a header (not shown) that can include, for example, the UE ID (e.g., MAC ID) of the transmitting device (e.g., the start side device). The basic fields 702 can include, for example, a start side field 704 that carries start side information, an anchor field 706 that carries anchor information, a power field 708 that carries power information, and a group ID field 710 that carries a group ID for the transmitting device. The start side information 704 indicates whether the transmitting device is the start side device of the positioning group. For example, the start side information 704 can include a single bit I={0,1}, where I = 1 indicates that the transmitting device is the start side device, and I = 0 indicates that the transmitting device is the response side device. The anchor information 706 indicates whether the transmitting device is an anchor device or a non-anchor device. For example, the anchor information 706 can include a single bit A={0,1}, where A = 1 indicates that the transmitting device is an anchor device, and A = 0 indicates that the transmitting device is a non-anchor device.

[0074]

[0090] Power information 708 indicates whether the transmitting device is power - limited (e.g., operating in DRX mode). For example, power information 708 may include a single - bit P = {0, 1}, where P = 1 indicates that the transmitting device is power - limited. In a P = 1 device, the PRS cycle periodicity may be smaller than the normal PRS cycle periodicity in order to adapt to the DRX mode of the transmitting device. Thus, a transmitting device with P = 1 may not transmit PRS within each PRS cycle during the PRS phase. Group ID 710 identifies the transmitting devices within a positioning group. In some examples, the group ID may be a random number within the group. For example, as shown in FIG. 7, the group ID may be a single - bit ID = {0, 1, ..., N} selected from mod(N). In other examples, the group ID may be the UE ID (e.g., MAC ID) of the transmitting device.

[0075]

[0091] FIG. 8 is a diagram showing an example of a group - formation broadcast message 800 that may be transmitted by the group - response side according to some aspects. In the example shown in FIG. 8, the payload of the group - formation broadcast message 800 includes a basic field 802 and a response - side field 804. The group - formation message 800 may further include a header (not shown) that includes, for example, the UE ID (e.g., MAC ID) of the transmitting response - side device. The basic field 802 includes the same fields as those shown in FIG. 7 and conveys the device information of the transmitting device (e.g., the response - side device that transmits the group - formation message 800). For example, the basic field 802 includes a start - side field 806 that conveys start - side information, an anchor field 808 that conveys anchor information, a power field 810 that conveys power information, and a group - ID field 812 that conveys the group ID for the transmitting device, as described above with respect to FIG. 7.

[0076]

[0092] The response - side field 804 may include a start - side ID field 814 that carries the start - side ID of the start - side device for the positioning group, and a response - side ID field 816 that carries a list of response - side IDs. Each of the response - side IDs included in the response - side ID field 816 is associated with a response - side device that transmitted a response - side group - formation message 800 in a response - side sub - phase that includes the start - side ID of the start - side device of the positioning group and the response - side ID of another response - side device that transmitted another response - side group - formation message 800 prior to the current response - side group - formation message 800. In some examples, the start - side ID and the response - side ID may be UE IDs for each of the start - side device and the response - side device. In other examples, the start - side ID and the response - side ID may each be based on the respective group IDs of the start - side device and the response - side device. For example, the start - side ID may include a concatenation of the start - side group ID and the start - side UE ID. Further, each of the response - side IDs may include a concatenation of the respective response - side group ID and the respective response - side UE ID. As another example, the start - side ID and the response - side ID may each include the start - side group ID and the response - side group ID, respectively.

[0077]

[0093] FIG. 9 is a diagram showing an example of a group - association broadcast message 900 that may be transmitted by a group start - side according to some aspects. In the example shown in FIG. 9, the payload of the group - association broadcast message 900 includes a basic field 902 and a response - side ID field 904. The group - association broadcast message 900 may further include a header (not shown) that includes, for example, the UE ID (e.g., MAC ID) of the start - side device. The basic field 902 includes the same fields as those shown in FIG. 7 and carries device information of the transmitting device (e.g., the start - side device that transmits the group - association message 900). For example, the basic field 902 includes a start - side field 906 that carries start - side information, an anchor field 908 that carries anchor information, a power field 910 that carries power information, and a group - ID field 912 that carries the group ID for the transmitting device.

[0078]

[0094] The responder ID field 904 includes a list of responder IDs 914 that identify members of the positioning group (e.g., responder devices) and the order of the responder devices within the positioning group. In some examples, the responder ID 914 can be a UE ID for each of the responder devices or a respective group ID. In other examples, each responder ID 914 can include a concatenation of a respective responder group ID and a respective responder UE ID for each responder device within the positioning group.

[0079]

[0095] The order of the responder IDs 914 included in the responder ID field 904 corresponds to the order of the responder devices within the positioning group (e.g., the order in which the responder devices can transmit their respective PRSs). In some examples, the responder IDs 914 are listed in descending order, where the top (first) responder ID identifies the first responder device that should transmit a PRS after the initiating device, the second responder ID identifies the second responder device that should transmit a PRS after the first responder device, and so on.

[0080]

[0096] In some examples, the order of the responder IDs 914 can be determined based on device information included in a basic field of a responder group formation message transmitted by each of the responder devices. For example, referring now to FIG. 8, the initiating field 806 can include a most significant bit (MSB), and the group ID field 812 can include a least significant bit (LSB). In this example, referring again to FIG. 9, the order of the responder IDs 914 in the responder ID field 904 can result in anchor devices being listed before non-anchor devices and power-constrained devices (which can generally be non-anchor devices) being listed after non-power-constrained devices. By placing power-constrained responder devices lower in the list of responder IDs, reduced latency between PRSs can be achieved even when a power-constrained device is not active during a particular PRS cycle.

[0081]

[0097] FIG. 10 is a diagram showing an example of positioning group formation by a plurality of wireless communication devices (WCD1 1002, WCD2 1004, WCD3 1006, WCD4 1008, and WCD5 1010) communicating on a sidelink channel according to some aspects. Each wireless communication device 1002, 1004, 1006, 1008, and 1010 may correspond to a sidelink device such as an RSU, V-UE, P-UE (e.g., a V2X device), or other sidelink devices. In the example shown in FIG. 10, WCD1 1002, WCD2 1004, and WCD4 1008 are anchor devices, and WCD3 1006 and WCD5 1010 are non-anchor devices.

[0082]

[0098] During the first start-side sub-phase 1012 of the group phase in the time domain, one or more of the anchor devices WCD1 1002, WCD2 1004, and WCD4 1008 can broadcast (or group-cast) a start-side group formation broadcast message (IGFM) on the sidelink channel. For example, at the first time (t1), WCD1 1002 can broadcast (or group-cast) a first start-side group formation message on the sidelink channel to form a positioning group 1018a including WCD1 1002. The first start-side group formation broadcast message can be received by each of the other wireless communication devices 1004, 1006, 1008, and 1010. Each receiving wireless communication device 1004, 1006, 1008, and 1010 can then determine whether to join the WCD1 positioning group 1018a based on the first start-side group formation message.

[0083]

[0099] For example, the WCD 4 1008 may receive a first start-side group formation broadcast message broadcast or group-cast from the WCD 1 1002, and measure the received power (e.g., RSRP) of the first start-side group formation message at the WCD 4 1008 to determine whether to join the WCD 1 positioning group 1018a. In some examples, the WCD 4 1008 may compare the received power of the first start-side group formation message with a threshold value (e.g., threshold power) to determine whether to join the WCD 1 positioning group 1018a. In one example, if the received power of the first start-side group formation message is less than the threshold value, and thus indicates that the WCD 1 1002 is located far from the WCD 4 1008, the WCD 4 1008 may determine not to join the WCD 1 positioning group 1018a. However, if the received power of the first start-side group message is greater than or equal to the threshold value, and thus indicates that the WCD 1 1002 is in proximity to the WCD 4 1008, as shown in the example of FIG. 10, the WCD 4 1008 may determine to join the WCD 1 positioning group 1018a. Thus, at the second time (t2), the WCD 4 1008 may not transmit a start-side group formation message.

[0084]

[0100] As another example, WCD2 1004 may also receive a first start-side group formation broadcast message broadcast (or group-cast) from WCD1 1002 and measure the received power of the first start-side group formation message at WCD2 1004. If the received power measured at WCD2 1004 is greater than or equal to a threshold (which may be the same as or different from the threshold used by, for example, WCD4 1008), WCD2 1004 may determine to join WCD1 positioning group 1018a. However, if the received power of the first start-side group message is less than the threshold, as shown in the example of FIG. 10, WCD2 1004 may determine not to join WCD1 positioning group 1018a. Thus, at the third time (t3), WCD2 1004 may broadcast a second start-side group formation message on the sidelink channel to form a second positioning group 1018b that includes WCD2 1004.

[0085]

[0101] During the response-side sub-phase 1014 of the group phase, the response-side devices can broadcast their respective response-side group formation messages (RGFMs) to join one of the positioning groups 1018a and 1018b. Here, the response-side devices include the anchor device WCD4 1008 and the non-anchor devices WCD3 1006 and WCD5 1010. Each of the response-side devices WCD3 1006, WCD4 1008, and WCD5 1010 receives each of the first start-side group formation message broadcast by WCD1 1002 and the second start-side group formation message broadcast by WCD2 1004, and based on the received start-side group formation messages, can determine whether to join WCD1 positioning group 1018a or WCD2 positioning group 1018b.

[0086]

[0102] For example, WCD3 1006 can receive a first start-side group formation broadcast message broadcast by WCD1 1002 and a second start-side group formation broadcast message broadcast by WCD2 1004. WCD3 1006 can further measure the received power (e.g., RSRP) of each of the first and second start-side group formation broadcast messages, compare the received power of each of the first and second start-side group formation broadcast messages, and select one of the positioning groups 1018a or 1018b based on the higher received power measured at WCD3 1006 for the first or second start-side group formation broadcast message. In the example shown in FIG. 10, the received power of the first start-side group formation broadcast message broadcast (or multicast) by WCD1 1002 measured by WCD3 1006 is higher than the received power of the second start-side group formation broadcast message broadcast (or multicast) by WCD2 1004. Therefore, at the fourth time (t4), WCD3 1006 can broadcast (or multicast) a first response-side group formation message to join the WCD1 positioning group 1018a. The first response-side group formation broadcast message can include the start-side ID of the start-side device WCD1 1002 and the device information of WCD3 1006 (e.g., the basic field 802 shown in FIG. 8).

[0087]

[0103] The anchor response side device WCD4 1008 chose not to transmit the start side group formation broadcast message during the start side sub-phase 1012 based on the high RSRP (e.g., greater than or equal to a threshold) measured by WCD4 1008 of the first start side group formation message broadcast by WCD1 1002 at the first time (t1). Therefore, during the response side sub-phase 1014, at the fifth time (t5), WCD4 1008 may broadcast (or group-cast) a second response side group formation broadcast message to join the WCD1 positioning group 1018a. The second response side group formation broadcast message may include the start side ID of the start side device WCD1 1002, the response side ID of WCD3 1006 that broadcast (or group-cast) the response side group formation broadcast message before to join the WCD1 positioning group 1018, and the device information of WCD4 1008 (e.g., the basic field 802 shown in FIG. 8).

[0088]

[0104] The non-anchor response side device WCD5 1010 may also receive the first start side group formation broadcast message sent by WCD1 1002 and the second start side group formation broadcast message sent by WCD2 1004. WCD5 1010 further measures the received power (e.g., RSRP) of each of the first and second start side group formation broadcast messages, compares the received power of each of the first and second start side group formation broadcast messages, and may select one of the positioning groups 1018a or 1018b based on the higher received power measured by WCD5 1010 of the first or second start side group formation message.

[0089]

[0105] Furthermore, WCD5 1010 may also receive each of the response-side group formation broadcast messages previously broadcast by WCD3 1006 and WCD4 1008 in response-side sub-phase 1014, and determine positioning groups 1018a and 1018b selected by each of the response-side devices WCD3 1006 and WCD4 1008. WCD5 1010 may further determine the number of response-side devices added to each of positioning groups 1018a and 1018b based on the received response-side group formation broadcast messages. Furthermore, WCD5 1010 may determine whether any of positioning groups 1018a and 1018b has reached the maximum number of members. For example, the maximum number of positioning group members may be pre-configured for all positioning groups or may be included in the start-side group formation message broadcast by the start-side device. For example, if positioning group 1018a reaches the maximum number of members, WCD5 1010 may select another positioning group 1018b. In an example where three or more positioning groups are available, WCD5 1010 may select the positioning group with the highest start-side group formation message RSRP that has not yet reached the maximum number of members.

[0090]

[0106] In the example shown in FIG. 10, at the sixth time (t6), WCD5 1010 may send a third response-side group formation broadcast message to join the WCD2 positioning group 1018b, based on either the higher received power of the start-side group formation message broadcast by WCD2 1004 or the fact that the maximum number of members has been reached for positioning group 1018a. The third response-side group formation broadcast message may include the start-side ID of the start-side device WCD2 1004 and the device information of WCD5 1010 (e.g., the basic field 802 shown in FIG. 8).

[0091]

[0107] During the second start-side sub-phase 1016, the start-side devices (e.g., WCD1 1002 and WCD2 1004) for each of the positioning groups 1018a and 1018b can send respective group-association broadcast messages that identify the members of each positioning group and specify the respective order of the members in that positioning group. For example, at the seventh time (t7), WCD1 1002 can send a first group-association broadcast message that includes the start-side ID of WCD1 1002 and the response-side IDs of WCD3 1006 and WCD4 1008 listed in the order for transmitting their respective PRSs. Further, at the eighth time (t8), WCD2 1004 can send a second group-association broadcast message that includes the start-side ID of WCD2 1004 and the response-side ID of WCD5 1010.

[0092]

[0108] FIG. 11 is a diagram showing an example of group-based PRS broadcast according to some aspects. The group-based PRS broadcast example shown in FIG. 11 can be implemented, for example, during a PRS cycle within the PRS phase in the time domain. As shown in FIG. 11, the starting-side device of the positioning group may reserve a sidelink channel for CoT 1102 sufficient for the transmission of PRS by each of the members of the positioning group. In some examples, the starting-side device reserves CoT 1102 for all positioning group members and may implement Cat4 LBT to transmit a first PRS (e.g., starting-side PRS 1104) at time T_{LBT}. Thereafter, the responding-side devices in the positioning group may implement Cat2 LBT to broadcast their PRSs 1106, 1108, 1110, and 1112. Each of the PRSs 1104-1112 may include its respective PRS sequence. For example, each PRS sequence may be a broadband random sequence broadcast on an unlicensed frequency band. In some examples, each PRS may further include a sequence identifier (ID) that identifies the PRS sequence. Each broadcast described herein may alternatively be a multicast, as described.

[0093]

[0109] Each responder device may determine the respective transmission timing of its PRS in the CoT 1102 from a group association message indicating the order of responder devices within a positioning group. For example, each PRS 1104-1112 may have the same (e.g., set) duration indicated as tPRS. Further, each responder device may provide a respective gap 1114 indicated as tgap between the end of the previously transmitted PRS and the responder device PRS. In some examples, the gap 1114 may be 25 μs. If the first responder device (R1) determines that it is listed first in the order of responder devices within the group association message, the first responder device (R1) may transmit a second PRS (R1 PRS) 1106 at time TLBT + tPRS + tgap. Similarly, the second responder device (R2) may transmit a third PRS (R2 PRS) at time TLBT + 2tPRS + 2tgap. Further, the third responder device (R3) may transmit a fourth PRS (R3 PRS) 1108 at time TLBT + 3tPRS + 3tgap. Generally, the k-th wireless communication device PRS broadcast time may be determined as TLBT + (k-1)tPRS + (k-1)tgap. By providing a fixed gap 1114 between PRSs and a known order of PRS transmissions, the latency between PRSs is reduced, and thus the efficiency and accuracy of sidelink positioning may be improved.

[0094]

[0110] Other responder devices (e.g., responder device R4) can transmit their respective PRSs (e.g., R4 PRS1112) at their respective transmission times determined similarly based on the order listed in the group association message. In some examples, a power-constrained (e.g., P = 1 in the device information shown in FIG. 8) responder device (RD) can be placed at the end of the responder list (e.g., below the order). Such a power-constrained responder device (e.g., responder device R4) can have a lower duty cycle than a non-power-constrained responder device (e.g., a responder device with P = 0), and thus may not transmit each PRS cycle, as indicated by the shading of R4 PRS1112. For example, a power-constrained responder device can transmit a PRS (and corresponding PRS measurement message) every 500 ms or 1000 ms, and a non-power-constrained responder device can transmit a PRS every 100 ms within the PRS phase. By placing the power-constrained responder device at the end of the list, the latency between successive PRS1104 - 1112 can be reduced during each PRS cycle.

[0095]

[0111] FIG. 12 shows an example of the configuration of devices belonging to two PRS broadcast positioning groups in a scenario suitable for opportunistic CoT sharing. Here, two positioning groups 1202a and 1202b are shown, but opportunistic CoT sharing can be similarly established among three or more positioning groups. Positioning group 1202a includes an anchor start-side device 1204 (shown as I_A), two anchor response-side devices 1206 and 1208 (shown as R1_A and R2_A), and two non-anchor response-side devices 1210 and 1212 (shown as R3_A and R4_A). Positioning group 1202b includes an anchor start-side device 1214 (shown as I_B), two anchor response-side devices 1216 and 1218 (shown as R1_B and R2_B), and a non-anchor response-side device 1220 (shown as R3_B). Each broadcast described herein can instead be a groupcast, as described.

[0096]

[0112] The two positioning groups 1202a and 1202b can be formed using messages such as an initiating-side group formation message (IGFM), a responding-side group formation message (RGFM), and a group association message (GAM), as previously described. Typically, when the two positioning groups 1202a and 1202b are formed, the start-side device of each positioning group can independently implement Cat4 LBT to reserve CoT for all positioning reference signals (PRS) of its group members. Thus, the start-side device 1204 (I_A) can independently implement Cat4 LBT to reserve CoT for the responding-side devices 1206 - 1212 (R1_A - R5_A). The start-side device 1214 (I_B) can independently implement Cat4 LBT to reserve a different CoT for the responding-side devices 1216 - 1220 (R1_B - R3_B).

[0097]

[0113] Group-internal PRS signaling for establishing RTT for positioning generally works well. The PRS signal latency is well managed within each positioning group. When CoT is established by the initiating device using Cat4 LBT, each PRS signal can be broadcast successively from different members of the positioning group (i.e., the initiating device and each subsequent responding device) in a well-controlled and predictable manner. To broadcast its PRS signal, each responding device in the positioning group can perform only Cat2 LBT with a simple Clear Channel Assessment (CCA), without the need to perform a contention channel "backoff" (as in the case of Cat4 LBT). Thus, within the positioning group, all group members can broadcast their PRS signals in order within a relatively tight and well-controlled time frame, i.e., within CoT. For example, the responding device 1206 (R1_A) and the responding device 1210 (R3_A) will broadcast their PRS signals within the same CoT. Therefore, the RTT measurement between these two devices will have a relatively low PRS latency.

[0098]

[0114] In contrast, inter-group PRS signaling for establishing RTT across members of different ranging groups can have the drawback of significantly long and not very predictable PRS latency, which can lead to significant degradation of RTT measurements. For example, the responder device 1212 (R4_A) from ranging group 1202a and the responder device 1216 (R1_B) from ranging group 1202b will typically not broadcast their PRS signals within the same CoT. The responder device 1212 (R4_A) will broadcast its PRS signal within the CoT established by the initiator device 1204 (I_A). The responder device 1216 (R1_B) will broadcast its PRS signal within a different CoT established by the initiator device 1214 (I_B). The two CoTs are established independently and each will have its own backoff. Thus, there can be significant latency between the PRS signal broadcast of the responder device 1212 (R4_A) from ranging group 1202a and the PRS signal broadcast of the responder device 1216 (R1_B) from ranging group 1202b. Such PRS signal latency can adversely affect the accuracy of the RTT measurements performed for ranging between the responder device 1212 (R4_A) and the responder device 1216 (R1_B).

[0099]

[0115] However, inter-group PRS signaling can be useful and appropriate in some scenarios. For example, the accuracy of certain multi-lateration operations can be significantly improved by including RTT measurements with anchors at or near a particular geographical location, and if the only available PRS-capable devices near that geographical location are devices belonging to different ranging groups, inter-group PRS signaling can be justified. The requirements for inter-group PRS can be triggered in several different ways, as described below.

[0100]

[0116] One category of such requests is sometimes referred to as "sensor-based" requests. One type of sensor-based trigger can be based on the frequency of receiving PRS signals from another positioning group. For example, if a positioning group is formed each time as a result of 10 PRS signal exchanges, and the response-side device 1220 (R3_B) from positioning group 1202b receives more than X times (e.g., X = 5) PRS from the devices in positioning group 1202a, the response-side device 1220 (R3_B) may request inter-group PRS signaling with positioning group 1202a. Another type of sensor-based trigger can be based on the received power of PRS signals from another positioning group. For example, if the response-side device 1220 (R3_B) from positioning group 1202b receives PRS from the devices in positioning group 1202a and the related reference signal received power (RSRP) measurement exceeds a certain threshold (e.g., in total, or in some other manner), the response-side device 1220 (R3_B) may request inter-group PRS signaling with positioning group 1202a. Another category of inter-group PRS signal requests is sometimes referred to as "core network" - based requests. Here, a central entity such as a core network (CN) within a cellular communication system that supports data communication with various sidelink devices including devices 1204 - 1220 may maintain positioning groups 1202a and 1202b. In such a scenario, the core network can determine and indicate the need for inter-group PRS signaling between positioning group 1202a and positioning group 1202b.

[0101]

[0117] The initiating device of a positioning group may respond by receiving a request for inter-group PRS signaling (from either one of its responder devices or the CN) and attempting to establish opportunistic CoT sharing between positioning groups. The initiating device may do so by coordinating with the initiating devices of other positioning groups. Such initiating-to-initiating coordination may be performed on a separate channel, such as a dedicated channel on the ITS band. For example, when the initiating device 1216 (I_B) of positioning group 1202b receives an inter-group PRS signaling request from the responder device 1220 (R3_B), it may coordinate with the initiating device 1204 (I_A) of positioning group 1202a. Alternatively, the initiating device may attempt to independently establish opportunistic CoT sharing without coordinating with other initiating devices. For example, when the initiating device 1216 (I_B) of positioning group 1202b receives an inter-group PRS signaling request from the responder device 1220 (R3_B), it may attempt to share the CoT established for positioning group 1202a without coordinating with the initiating device 1204 (I_A).

[0102]

[0118] Figure 13 is a timing diagram showing an example of an opportunity for CoT sharing between two PRS broadcast positioning groups. CoT sharing between three or more groups may be implemented in a similar manner. However, for ease of explanation, only two groups are shown. As described, opportunistic CoT sharing may be performed with or without coordination between the initiating sides of the respective positioning groups. Each broadcast described in this specification may alternatively be a multicast, as described.

[0103]

[0119] Referring to FIG. 13, two PRS broadcast sequences 1302 and 1304 are shown. The first PRS broadcast sequence 1302 occurs within CoT 1306. The first PRS broadcast sequence 1302 includes a start-side PRS 1314 and four response-side PRSs 1316, 1318, 1320, and 1322, which are broadcast from a start-side device 1204 (from the positioning group 1202a shown in FIG. 12) and four response-side devices 1206, 1208, 1210, and 1212, respectively, to form a sequence of PRS broadcasts. The start-side device 1204 may establish CoT 1306 by performing Cat4 LBT, which may set the start time of CoT 1306 based on a backoff time (“backoff A”) 1324. The second PRS broadcast sequence 1304 occurs within CoT 1326. The second PRS broadcast sequence 1304 includes a start-side PRS 1334 and three response-side PRSs 1336, 1338, and 1340, which are broadcast from a start-side device 1214 (from the positioning group 1202b shown in FIG. 12) and three response-side devices 1216, 1218, and 1220, respectively, to form a sequence of PRS broadcasts. The start-side device 1214 may establish CoT 1326 by performing Cat4 LBT, which may set the start time of CoT 1326 based on a backoff time (“backoff B”) 1342.

[0104]

[0120] When the starting-side device 1202 and the starting-side device 1204 cooperate to establish CoT sharing, they may each perform Cat4 LBT using a backoff counter initialized with a random number selected from an interval proportional to the sum of (1) the number of devices in its positioning group and (2) the number of devices in the other positioning groups. Here, the sum of the number of devices from both groups is 5 + 4 = 9. Therefore, the starting-side device 1202 and the starting-side device 1204 each use a random number generator characterized by a uniform probability distribution function over the interval [0, 9] to generate a random number in order to determine their respective backoff times. As shown in FIG. 13, the starting-side device 1202 thus generates a backoff time 1324. The starting-side device 1204 thus generates a backoff time 1342.

[0105]

[0121] When the starting-side device 1202 and the starting-side device 1204 do not cooperate to establish CoT sharing, they may each perform Cat4 LBT using a backoff counter initialized with a random number selected from an interval proportional to the number of devices in its own positioning group. Therefore, since there are 5 devices in the positioning group 1202a, the starting-side device 1202 will generate a backoff time 1324 using a random number generator characterized by a uniform probability distribution function over the interval [0, 5]. Since there are 4 devices in the positioning group 1202b, the starting-side device 1204 will generate a backoff time 1326 using a random number generator characterized by a uniform probability distribution function over the interval [0, 4].

[0106]

[0122] Regardless of whether the initiating devices 1202 and 1204 cooperate in the established CoT sharing, the initiating device 1204 may attempt to "match" the PRS associated with the positioning group 1202b to the CoT 1306 scheduled for the PRS associated with the positioning group 1202a. Since all group messages, including all group formation messages (IGFMs), responder group formation messages (RGFMs), and group association messages (GAMs), are listened for by all devices, the initiating device 1204 is aware of the membership, order, etc. of the positioning group 1202a. Thus, the positioning group 1202b can determine the total PRS sequence duration 1344 of the PRS of the positioning group 1202a. The duration of the CoT 1306 is also generally known. The initiating device 1204 can thus determine whether there is sufficient room within the CoT 1306 to match the PRS for the positioning group 1202b. For example, if the remaining time within the CoT 1306 is greater than the duration 1346 of the PRS of the positioning group 1206b, the initiating device 1204 can proceed with an attempt to broadcast the PRS of the positioning group 1202b within the CoT 1306.

[0107]

[0123] As described above, positioning reference signals (PRSs) are used as examples to illustrate various aspects, but different types of reference signals, such as sounding reference signals (SRSs) or other types of signals, may be used instead.

[0108]

[0124] FIG. 14 shows a successful attempt to opportunistically share CoT according to one embodiment. As explained in the context of FIG. 13, the initiating device 1202 and the initiating device 1204 may each perform Cat4 LBT and plan to schedule their respective CoTs. In doing so, each of the initiating device 1202 and the initiating device 1204 may set a backoff using a randomly selected number. The first initiating device to finish counting down its backoff time and successfully complete a clear channel assessment (CCA) proceeds to establish a CoT to broadcast a PRS signal to its positioning group. In this case, the initiating device 1202 first finishes counting down its backoff time 1324 at time 1402 and successfully completes the CCA. Accordingly, the initiating device 1202 establishes CoT 1306, broadcasts its PRS 1314, and its responding devices broadcast PRS 1316, 1318, 1320, and 1322, respectively. Each broadcast described herein may alternatively be a multicast as described.

[0109]

[0125] In response, the initiating device 1304 evaluates two conditions. First, the initiating device 1304 determines whether CoT 1306 has sufficient margin after PRSs 1314, 1316, 1318, 1320, and 1322 to accommodate the PRSs for positioning group 1202b, i.e., PRSs 1334, 1336, 1338, and 1340. In this example, there is sufficient margin. In other words, the duration LB 1346 is less than the CoT-duration LA 1344 (LB < CoT-LB). Second, the initiating device 1304 performs Cat2 LBT at time 1404 at the end of the PRS for positioning group 1202a. Cat2 LBT includes a Clear Channel Assessment (CCA). Here, the CCA is completed successfully (CCA_B = 1). If both conditions are met, the initiating device 1304 proceeds to broadcast its PRS 1334. The responder side of the initiating device 1304 also broadcasts their respective PRSs 1336, 1338, and 1340. In this way, the initiating device 1304 may avoid the planned Cat4 LBT to establish its own CoT. Instead, the initiating device 1304 successfully shares the CoT 1306 established by the initiator 1302 in an opportunistic manner.

[0110]

[0126] FIG. 15 shows an unsuccessful attempt to opportunistically share CoT as a result of insufficient transmission time. Similar to the scenario in FIG. 14, the initiating device 1202 first finishes counting down its backoff time 1324 and successfully completes CCA. Thus, the initiating device 1202 establishes CoT 1306, broadcasts its PRS 1314, and its responding devices each broadcast PRS 1316, 1318, 1320, and 1322. In response, the initiating device 1304 evaluates the same two conditions described previously. Here, the initiating device 1304 determines that there is insufficient margin to accommodate the PRS for the positioning group 1202b after CoT 1306 has PRS 1314, 1316, 1318, 1320, and 1322. In other words, the duration LB 1346 is greater than CoT 1306 - duration LA 1344 (LB>CoT-LB). Having determined that opportunistic sharing of CoT 1306 is not possible, the initiating device 1304 retrieves the backoff time 1342 it previously generated. The initiating device 1304 uses the backoff time 1342 to perform Cat4 LBT at time 1502 to establish its own CoT 1326 as originally planned. The initiating device 1304 then proceeds to broadcast its PRS 1334, and the responding sides of the initiating device 1304 also broadcast their respective PRS 1336, 1338, and 1340 within CoT 1326. Each broadcast described herein may alternatively be a groupcast as described.

[0111]

[0127] FIG. 16 shows a failed attempt to opportunistically share CoT as a result of a failed Clear Channel Assessment (CCA) according to one embodiment. Similar to the scenarios in FIGS. 14 and 15, the initiating device 1202 first finishes counting down its backoff time 1324 and successfully completes the CCA. Thus, the initiating device 1202 establishes CoT 1306, broadcasts its PRS 1314, and its responding devices each broadcast PRS 1316, 1318, 1320, and 1322. In response, the initiating device 1304 evaluates the same two conditions described previously. Here, the initiating device 1304 determines that there is sufficient margin for adapting the PRS for the positioning group 1202b after CoT 1306 has PRS 1314, 1316, 1318, 1320, and 1322. In other words, the duration LB 1346 is smaller than CoT 1306 - duration LA 1344 (LB < CoT - LB). Next, the initiating device 1304 performs a Cat2 LBT with CCA at time 1602 at the end of the PRS of the positioning group 1202a. In this case, an interferer signal 1604 is present when the CCA is performed and the CCA fails (CCA_B = 0). As a result, the attempt to share CoT 1306 is aborted. Also, if it is determined that opportunistic sharing of CoT 1306 is not performed, the initiating device 1304 retrieves the backoff time 1342 it previously generated. The initiating device 1304 uses the backoff time 1342 to perform a Cat4 LBT at time 1606 to establish its own CoT 1326 as originally planned. The initiating device 1304 then proceeds to broadcast its PRS 1334, and the responding side of the initiating device 1304 also broadcasts their respective PRS 1336, 1338, and 1340 within CoT 1326. Each broadcast described herein may alternatively be a groupcast as described.

[0112]

[0128] FIG. 17 is a block diagram illustrating an example of a hardware implementation for a wireless communication device 1700 that employs a processing system 1714. For example, the wireless communication device 1700 can correspond to a sidelink (e.g., V2X) device such as an RSU, V-UE, P-UE, etc., or other suitable sidelink devices as shown and described above with reference to FIGS. 1-5 or 10.

[0113]

[0129] The wireless communication device 1700 can be implemented using a processing system 1714 that includes one or more processors 1704. Examples of processors 1704 include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic, individual hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. In various examples, the wireless communication device 1700 can be configured to perform any one or more of the functions described herein. That is, the processor 1704 utilized in the wireless communication device 1700 can be used to implement any one or more of the processes and procedures described below.

[0114]

[0130] In this example, the processing system 1714 can be implemented using a bus architecture schematically represented by bus 1702. Bus 1702 can include any number of interconnecting buses and bridges depending on the specific application of the processing system 1714 and overall design constraints. Bus 1702 links together various circuits including one or more processors (schematically represented by processor 1704), memory 1705, and a computer-readable medium (schematically represented by computer-readable medium 1706). Bus 1702 can also link various other circuits such as a timing source, peripherals, voltage regulators, and power management circuits, which are well known in the art and thus will not be described further.

[0115]

[0131] The bus interface 1708 provides an interface between the bus 1702 and the transceiver 1710. The transceiver 1710 provides means for communicating with various other devices via a transmission medium (e.g., an air interface). The bus interface 1708 further provides an interface between the bus 1702 and a power source (e.g., a battery) 1720. Depending on the nature of the device, a user interface 1712 (e.g., a keypad, a display, a touch screen, a speaker, a microphone, a control knob, etc.) may also be provided. Of course, such a user interface 1712 is optional and may be omitted in some examples.

[0116]

[0132] The processor 1704 is responsible for managing the bus 1702 and general processing including the execution of software stored in the computer-readable medium 1706. The software is broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc., regardless of the name such as software, firmware, middleware, microcode, hardware description language. When the software is executed by the processor 1704, it causes the processing system 1714 to perform various functions described below for a particular device. The computer-readable medium 1706 and the memory 1705 may also be used to store data that is manipulated by the processor 1704 when executing the software.

[0117]

[0133] The computer-readable medium 1706 can be a non-transitory computer-readable medium. Non-transitory computer-readable media include, by way of example, magnetic storage devices (such as hard disks, floppy (registered trademark) disks, magnetic strips), optical disks (such as compact discs (CDs) or digital versatile discs (DVDs)), smart cards, flash memory devices (such as cards, sticks, or key drives), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM (registered trademark)), registers, removable disks, and any other suitable medium for storing software and / or instructions that can be accessed and read by a computer. The computer-readable medium 1706 can reside within the processing system 1714, be external to the processing system 1714, or be distributed across multiple entities including the processing system 1714. The computer-readable medium 1706 can be embodied in a computer program product. By way of example, the computer program product can include the computer-readable medium in a packaging material. In some examples, the computer-readable medium 1706 can be part of the memory 1705. Those skilled in the art will recognize how best to implement the described functions presented throughout this disclosure, depending on the particular applications and overall design constraints imposed on the overall system.

[0118]

[0134] In some aspects of the present disclosure, processor 1704 may include circuitry configured for various functions. For example, processor 1704 may include communication and processing circuitry 1742 configured to communicate with other wireless communication devices (e.g., RSU, V-UE, P-UE, etc.) over a sidelink channel. In some examples, communication and processing circuitry 1742 may include one or more hardware components that provide a physical structure for performing processes related to wireless communication (e.g., signal reception and / or signal transmission) and signal processing (e.g., processing received signals and / or processing signals for transmission).

[0119]

[0135] In some examples, communication and processing circuitry 1742 may be configured to broadcast group formation messages over a sidelink channel via transceiver 1710. Communication and processing circuitry 1742 may be further configured to receive one or more group formation messages broadcast by other wireless communication devices via transceiver 1710. Communication and processing circuitry 1742 may be further configured to store received group formation messages (GFM) 1716 in memory 1705 for further processing.

[0120]

[0136] Communication and processing circuitry 1742 may be further configured to broadcast or receive a group association message (GAM) 1718 indicating an order 1722 of a plurality of wireless communication devices within a positioning group including wireless communication device 1700 via transceiver 1710. Communication and processing circuitry 1742 may be further configured to broadcast a positioning reference signal (PRS) within the positioning group and receive a PRS broadcast from other wireless communication devices within the positioning group. Communication and processing circuitry 1742 may be further configured to execute communication and processing instructions (software) 1752 stored in computer-readable medium 1706 to implement one or more of the functions described herein.

[0121]

[0137] The processor 1704 may further include a group formation circuit 1744 configured to generate group formation messages (e.g., an initiating side group formation message or a responding side group formation message) to be broadcast on the sidelink channel and process group formation messages (e.g., an initiating side group formation message and / or a responding side group formation message) received from other wireless communication devices. In an example where the wireless communication device 1700 is an anchor device, the group formation circuit 1744 may be configured to determine whether the initiating side group formation message was received from another anchor initiating side wireless communication device during an initiating side sub-phase of a current group phase in which a positioning group may be formed.

[0122]

[0138] When a start-side group formation message is received, the group formation circuit 1744 measures the received power of the start-side group formation message (e.g., RSRP), and can compare the received power with a threshold value 1724 that can be stored in, for example, the memory 1705. If the received power of the start-side group formation message is greater than the threshold value 1724, the start-side group formation message 1716 is stored in the memory 1705 and can be used by the group formation circuit 1744 to generate a response-side group formation message during the response-side sub-phase of the current group phase to join the positioning group started by the start-side group formation message. Here, the anchor device 1700 functions as a response-side device. Otherwise, if the received power of the start-side group formation message is less than or equal to the threshold value 1724, the group formation circuit 1744 discards the received start-side group formation message and can generate a new start-side group formation message to form a new positioning group for the wireless communication device 1700. Here, the anchor device functions as a start-side device. If another start-side group formation message is not received within the start-side sub-phase, the anchor device 1700 can function as a start-side device, and the group formation circuit 1744 can generate a start-side group formation message to form a positioning group for the wireless communication device 1700.

[0123]

[0139] In an example where the wireless communication device 1700 is a starting - side device that broadcasts a starting - side group - formation message during the current starting - side sub - phase to form a positioning group, the group - formation circuit 1744 can be further configured to receive one or more response - side group - formation messages 1716 from response - side devices within the response - side sub - phase of the current group phase. Each response - side group - formation message 1716 can include, for example, device information associated with each respective response - side device, the starting - side ID of the starting - side device 1700, and the respective response - side IDs of other response - side devices that previously broadcast the response - side group - formation message to join the positioning group of the starting - side device 1700. The received response - side group - formation messages 1716 can be stored in the memory 1705, for example, for further processing. For example, the group - formation circuit 1744 can be further configured to utilize the received response - side group - formation messages 1716 to determine the order 1722 of the response - side devices for transmitting their respective PRSs within the PRS phase that is temporally after the current group phase. The order 1722 can be based on, for example, the device information associated with each response - side device. In some examples, the order 1722 can include a list of response - side devices in descending order such that the first - listed response - side device should broadcast its PRS after the starting - side device, the second - listed response - side device should broadcast its PRS after the first - listed response - side device, and so on. The group - formation circuit 1744 can be further configured to generate a group - association message (GAM) 1718 for the positioning group. The GAM 1718 can include, for example, the starting - side ID of the starting - side device 1700 and the order 1722 of the response - side devices. The GAM 1718 can be broadcast within the second starting - side sub - phase of the current group phase.

[0124]

[0140] In an example where the wireless communication device 1700 is a non-anchor device, the non-anchor device 1700 may determine whether the start-side group formation message was received from the start-side device during the start-side sub-phase of the current group phase. If the start-side group formation message has not yet been received, the group formation circuit 1744 may generate the start-side group formation message and function as the start-side device to broadcast the start-side group formation message during the response-side sub-phase of the current group phase to form a positioning group for the non-anchor device 1700.

[0125]

[0141] If one or more start-side group formation messages 1716 are received, the non-anchor device 1700 may function as a response-side device to select the positioning group to join based on the received start-side group formation message 1716. The received start-side group formation message may be stored in the memory 1705, for example, until a positioning group is selected for the non-anchor device. For example, the group formation circuit 1744 may measure the received power (e.g., RSRP) of each start-side group formation message 1716 and select the positioning group associated with the start-side group formation message 1716 having the highest received power.

[0126]

[0142] As another example, the group formation circuit 1744 may determine the number of members of each of the positioning groups associated with the received start-side group formation message 1716. The number of members of a particular positioning group may be determined based on, for example, the response-side group formation message 1716 received for that particular positioning group during the response-side sub-phase of the current group phase. For example, the group formation circuit 1744 may be configured to count the number of response-side group formation messages 1716 received for each positioning group. If the number of members of a positioning group reaches the maximum number of members, the group formation circuit 1744 may not select that positioning group. Instead, the group formation circuit 1744 may select another positioning group whose number of members has not reached the maximum number of members. Here, the maximum number of members for a positioning group is predetermined and may be stored in, for example, the memory 1705 or included in the start-side group formation message. In some examples, the group formation circuit 1744 may further select a positioning group from the remaining positioning groups having a number of members smaller than the maximum number of members based on the received power of the corresponding start-side group formation message 1716.

[0127]

[0143] When a ranging group to be added is selected, the group formation circuit 1744 may generate a response-side group formation message to be broadcast during the response-side sub-phase of the current group phase. The response-side group formation message may include, for example, device information associated with the non-anchor device 1700, the start-side ID of the start-side device for the selected ranging group, and the respective response-side IDs of the response-side devices that broadcast the response-side group formation message 1716 prior to the generation of the response-side group formation message by the group formation circuit 1744 to join the ranging group prior to the generation of the response-side group formation message by the group formation circuit 1744. Further, the group formation circuit 1744 may receive a GAM 1718 including the order 1722 of the response-side devices from the start-side device of the ranging group. The group formation circuit 1744 may be further configured to execute group formation instructions (software) 1754 stored in the computer-readable medium 1706 to implement one or more of the functions described herein.

[0128]

[0144] Processor 1704 may further include a PRS generation circuit 1746 configured to generate PRS to be broadcast to a positioning group during a PRS phase. For example, the PRS may include a PRS sequence. The PRS sequence may be a wideband random sequence broadcast on an unlicensed frequency band. In some examples, the PRS may include a sequence identifier (ID) that identifies the PRS sequence. The PRS generation circuit 1746 may further determine the transmission timing of the PRS based on the order 1722 of the wireless communication devices in the positioning group. In an example where the wireless communication device is a start-side device of the positioning group, the PRS generation circuit 1746 may reserve a sidelink channel for CoT and be configured to implement Cat4 LBT to broadcast a first PRS to the positioning group within the CoT. In an example where the wireless communication device is a response-side device, the PRS generation circuit 1746 may be configured to broadcast the PRS to the positioning group within the CoT at a transmission time determined from the order 1722 of the response-side device. The PRS generation circuit 1746 may be further configured to execute PRS generation instructions (software) 1756 stored in a computer-readable medium 1706 to implement one or more of the functions described herein.

[0129]

[0145] FIG. 18 is a flowchart 1800 of an exemplary method for group-based PRS broadcast according to some aspects. As described below, some or all of the illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some of the illustrated features may not be required for the implementation of all embodiments. In some examples, the method may be implemented by a processor or processing system, or by any suitable means for performing the described functions, by the wireless communication device 1700 described above and shown in FIG. 17.

[0130]

[0146] In block 1802, a wireless communication device (e.g., a first wireless communication device) may transmit a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device. In some examples, the first wireless communication device may transmit the first group formation broadcast message within a group phase in the time domain. The group phase may include at least a start-side sub-phase in which start-side devices can broadcast their respective group formation broadcast messages, and a response-side sub-phase in which response-side devices can broadcast their respective group formation broadcast messages. The start-side devices may include at least anchor devices each having a respective known location based on location accuracy. The response-side devices may include at least non-anchor devices each having a respective unknown location based on location accuracy.

[0131]

[0147] In block 1804, the first wireless communication device may receive a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, and the second positioning group is associated with channel occupancy time (CoT) in the sidelink channel. The second plurality of wireless communication devices may be configured to communicate a reference signal (e.g., PRS) using a transmission opportunity within the CoT.

[0132]

[0148] In block 1806, the first wireless communication device may start the transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group. For example, the PRS generation circuit 1746, shown with respect to FIG. 17 and described above, may provide means for transmitting a reference signal, together with the communication and processing circuit 1742 and the transceiver 1710.

[0133]

[0149] In one configuration, the wireless communication device 1700 includes means for group-based PRS broadcast as described in this disclosure. In one aspect, the means described above can be the processor 1704 shown in FIG. 17 configured to implement the functions implemented by the means described above. In another aspect, the means described above can be a circuit or any device configured to implement the functions implemented by the means described above.

[0134]

[0150] Of course, in the above example, the circuit included in the processor 1704 is provided only as an example and is not limiting. It includes instructions stored in the computer-readable storage medium 1706, or any other suitable device or means described in any one of FIGS. 1-5, 10, and / or 17, and, for example, utilizes the processes and / or algorithms described herein with respect to FIG. 18. Other means for performing the described functions may be included within various aspects of the present disclosure.

[0135]

[0151] Some aspects of a wireless communication network have been presented with reference to exemplary implementations. As will be readily appreciated by those skilled in the art, the various aspects described throughout this disclosure can be extended to other telecommunication systems, network architectures, and communication standards.

[0136]

[0152] As an example, various aspects may be implemented within other systems defined by the 3rd Generation Partnership Project (3GPP), such as Long Term Evolution (LTE), Evolved Packet System (EPS), Universal Mobile Telecommunications System (UMTS), and / or Global System for Mobile Communications (GSM®). Various aspects may also be extended to systems defined by the 3rd Generation Partnership Project 2 (3GPP2), such as CDMA2000 and / or Evolution-Data Optimized (EV-DO). Other examples may be implemented within IEEE802.11 (Wi-Fi®), IEEE802.16 (WiMAX®), IEEE802.20, Ultra Wide Band (UWB), systems employing Bluetooth®, and / or other suitable systems. The actual telecommunications standard, network architecture, and / or communication standard employed will depend on the overall design constraints imposed on a particular application and system.

[0137]

[0153] Within this disclosure, the word "exemplary" is used to mean "an example, instance, or serving as an illustration." Any implementation or aspect described herein as "exemplary" should not necessarily be construed as being more preferred or advantageous than other aspects of the disclosure. Similarly, the term "aspect" does not necessarily require that all aspects of the disclosure include the described features, advantages, or modes of operation. The term "coupled" is used herein to refer to either a direct or an indirect connection between two objects. For example, if object A physically contacts object B and object B contacts object C, objects A and C can be considered to be coupled to each other even if they do not directly physically contact each other. For example, a first object can be coupled to a second object even if the first object never directly physically contacts the second object. The terms "circuit" and "circuitry" are widely used and, when connected and configured, include both hardware implementations of electrical devices and conductors that enable the performance of the functions described in this disclosure without limitation as to the type of electronic circuit, as well as software implementations of information and instructions that enable the performance of the functions described in this disclosure when executed by a processor.

[0138]

[0154] One or more of the components, steps, features, and / or functions shown in FIGS. 1-18 may be reconfigured and / or combined into a single component, step, feature, or function, or embodied in several components, steps, or functions. Additional elements, components, steps, and / or functions may also be added without departing from the novel features disclosed herein. The apparatus, device, and / or components shown in FIGS. 1-5, 10, and / or 17 may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and / or incorporated into hardware.

[0139]

[0155] It should be understood that the specific order or hierarchy of steps in the disclosed method is an example of an exemplary process. Based on design preferences, it should be understood that the specific order or hierarchy of steps in this method can be rearranged. The appended method claims present the elements of the various steps in an exemplary order and are not limited to the specific order or hierarchy presented, unless otherwise specifically recited in the method claims.

[0140]

[0156] The foregoing description has been provided to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Accordingly, the claims are not limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, wherein reference to singular elements is not to be construed as meaning "sole and exclusive" unless explicitly so stated, but rather "one or more." Unless otherwise specified, the term "some" refers to one or more. Clauses referring to "at least one of" a list of items refer to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" shall be taken to include a, b, c, a and b, a and c, b and c, as well as a, b, and c. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure, known or later to become known to those skilled in the art, are hereby expressly incorporated herein by reference and are to be included within the claims. Moreover, nothing disclosed herein is to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

[0141]

[0157] Implementation examples are described in the clauses numbered below.

[0142]

[0158] Clause 1: A method for device location estimation, comprising, in a first wireless communication device, transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device; wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal, and starting transmission of the reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0143]

[0159] Clause 2: Starting transmission of the reference signal by the first plurality of wireless communication devices comprises, in the first wireless communication device, sending a first reference signal in an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, using a first one of the additional transmission opportunities within the CoT associated with the second positioning group, according to the method of Clause 1.

[0144]

[0160] Clause 3: The method according to any one of Clauses 1 to 2, further comprising, in the first wireless communication device, broadcasting a group association broadcast message specifying an order of transmission for an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, before sending the first reference signal.

[0145]

[0161] Clause 4: Starting transmission of the reference signal by the first plurality of wireless communication devices is performed in response to a sensor-based trigger, according to the method of any one of Clauses 1 to 3.

[0146]

[0162] Clause 5: The method according to clause 4, wherein the sensor-based trigger is based on the frequency of the received reference signal from the second plurality of wireless communication devices.

[0147]

[0163] Clause 6: The method according to clause 4, wherein the sensor-based trigger is based on one or more received power measurements associated with one or more reference signals received from the second plurality of wireless communication devices.

[0148]

[0164] Clause 7: The method according to any one of clauses 1 to 3, wherein the transmission of the reference signal by the first plurality of wireless communication devices is initiated in response to a network-based trigger.

[0149]

[0165] Clause 8: The method according to any one of clauses 1 to 7, further comprising cooperating with the second wireless communication device to establish sharing of CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices.

[0150]

[0166] Clause 9: The method according to clause 8, wherein the start time for CoT is based on a backoff time selected from an interval based on (a) the count of the number of reference signals associated with the first plurality of wireless communication devices and (b) the count of the number of reference signals associated with the second plurality of wireless communication devices.

[0151]

[0167] Clause 10: The method according to any one of clauses 1 to 9, further comprising independently establishing sharing of CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices without cooperating with the second wireless communication device.

[0152]

[0168] Clause 11: The method according to clause 10, wherein the start time for CoT is based on a backoff time selected from an interval based on the count of the number of reference signals associated with the second plurality of wireless communication devices.

[0153]

[0169] Clause 12: determining a first duration for transmission of a reference signal by a first plurality of wireless communication devices, determining a second duration for transmission of a reference signal by a second plurality of wireless communication devices, and using additional transmission opportunities within the CoT associated with the second positioning group to confirm that the first duration of transmission of the reference signal is less than the second duration of transmission of the CoT-reference signal before starting the transmission of the reference signal by the first plurality of wireless communication devices, the method according to any one of Clauses 1 to 11.

[0154]

[0170] Clause 13: further comprising performing a successful clear channel assessment (CCA) before starting the transmission of the reference signal by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group, the method according to Clause 12.

[0155]

[0171] Clause 14: the method according to any one of Clauses 1 to 13, wherein the reference signal supports round-trip time (RTT) measurements between (a) at least one wireless communication device among the first plurality of wireless communication devices and (b) at least one wireless communication device among the second plurality of wireless communication devices.

[0156]

[0172] Clause 15: the method according to any one of Clauses 1 to 14, further comprising communicating with the second wireless communication device using a separate channel.

[0157]

[0173] Clause 16: the method according to Clause 15, wherein the separate channel is arranged within the frequency band of the advanced road traffic system (ITS).

[0158]

[0174] Clause 17: the method according to any one of Clauses 1 to 16, wherein the sidelink channel is arranged within the unlicensed spectrum.

[0159]

[0175] Clause 18: A first wireless communication device in a wireless communication network, comprising a wireless transceiver, a memory, and a processor communicatively coupled to the wireless transceiver and the memory, wherein the processor is configured to: use the wireless transceiver to transmit a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; use the wireless transceiver to receive a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device; wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal, and within the CoT associated with the second positioning group, start transmitting the reference signal by the first plurality of wireless communication devices using an additional transmission opportunity.

[0160]

[0176] Clause 19: The first wireless communication device according to clause 18, wherein the processor is configured to start transmitting the reference signal by the first plurality of wireless communication devices by sending a first reference signal in an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, using a first one of the additional transmission opportunities within the CoT associated with the second positioning group.

[0161]

[0177] Clause 20: The first wireless communication device according to clause 19, further configured such that the processor broadcasts a group association broadcast message specifying a transmission order for an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, before sending the first reference signal.

[0162]

[0178] Clause 21: The first wireless communication device according to any one of Clauses 18 to 20, further configured such that the processor starts transmission of a reference signal by the first plurality of wireless communication devices in response to a sensor-based trigger.

[0163]

[0179] Clause 22: The first wireless communication device according to Clause 21, wherein the sensor-based trigger is based on the frequency of received reference signals from the second plurality of wireless communication devices.

[0164]

[0180] Clause 23: The first wireless communication device according to Clause 21, wherein the sensor-based trigger is based on one or more received power measurements associated with one or more reference signals received from the second plurality of wireless communication devices.

[0165]

[0181] Clause 24: The first wireless communication device according to any one of Clauses 18 to 20, further configured such that the processor starts transmission of a reference signal by the first plurality of wireless communication devices in response to a network-based trigger.

[0166]

[0182] Clause 25: The first wireless communication device according to any one of Clauses 18 to 24, further configured such that the processor cooperates with the second wireless communication device to establish sharing of CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices.

[0167]

[0183] Clause 26: The first wireless communication device according to Clause 25, wherein the start time for CoT is based on a backoff time selected from intervals based on (a) a count of the number of reference signals associated with the first plurality of wireless communication devices and (b) a count of the number of reference signals associated with the second plurality of wireless communication devices.

[0168]

[0184] Clause 27: The first wireless communication device according to any of Clauses 18 to 24, further configured such that the processor independently establishes sharing of CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices without cooperating with the second wireless communication device.

[0169]

[0185] Clause 28: The first wireless communication device according to Clause 27, wherein a start time of CoT is based on a backoff time selected from intervals based on counting the number of reference signals associated with the second plurality of wireless communication devices.

[0170]

[0186] Clause 29: The processor determines a first duration for transmission of a reference signal by the first plurality of wireless communication devices, determines a second duration for transmission of a reference signal by the second plurality of wireless communication devices, and uses additional transmission opportunities within CoT associated with the second positioning group to confirm that the first duration of transmission of the reference signal is less than the second duration of transmission of the CoT-reference signal before starting transmission of the reference signal by the first plurality of wireless communication devices. The first wireless communication device according to any of Clauses 18 to 28, further configured to perform the above.

[0171]

[0187] Clause 30: The first wireless communication device according to Clause 29, further configured such that the processor performs a successful clear channel assessment (CCA) before starting transmission of a reference signal by the first plurality of wireless communication devices using additional transmission opportunities within CoT associated with the second positioning group.

[0172]

[0188] Clause 31: The first wireless communication device according to any one of Clauses 18 to 30, wherein the reference signal supports round-trip time (RTT) measurements between (a) at least one wireless communication device among the first plurality of wireless communication devices and (b) at least one wireless communication device among the second plurality of wireless communication devices.

[0173]

[0189] Clause 32: The first wireless communication device according to any one of Clauses 18 to 31, further configured such that the processor communicates with the second wireless communication device using a separate channel.

[0174]

[0190] Clause 33: The first wireless communication device according to Clause 32, wherein the separate channel is arranged within the advanced road traffic system (ITS) frequency band.

[0175]

[0191] Clause 34: The first wireless communication device according to any one of Clauses 18 to 33, wherein the sidelink channel is arranged within the unlicensed spectrum.

[0176]

[0192] Clause 35: A first wireless communication device in a wireless communication network, comprising means for transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device, means for receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal, and means for starting transmission of the reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group.

[0177]

[0193] Clause 36: A non - transitory computer - readable medium storing instructions for execution by one or more processing units, the instructions comprising: transmitting a first group - forming broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including a first wireless communication device; receiving a second group - forming broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device; wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal, and starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group. The invention described in the claims of the present application at the time of filing is appended below. [C1] A method for device location estimation, in a first wireless communication device, transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal; starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group. A method comprising: [C2] Said starting said transmission of said reference signal by said first plurality of wireless communication devices, in said first wireless communication device, transmitting a first reference signal in an ordered sequence of reference signals to be sent from said first plurality of wireless communication devices, using a first one of said additional transmission opportunities within said CoT associated with said second positioning group; The method according to C1, comprising: [C3] In said first wireless communication device, prior to transmitting said first reference signal, broadcasting a group association broadcast message specifying an order of transmission for said ordered sequence of reference signals to be sent from said first plurality of wireless communication devices; The method according to C2, further comprising: [C4] Said starting said transmission of said reference signal by said first plurality of wireless communication devices is performed in response to a sensor-based trigger. The method according to C1. [C5] Said sensor-based trigger is based on the frequency of received reference signals from said second plurality of wireless communication devices. The method according to C4. [C6] The sensor-based trigger is the method according to C4, based on one or more received power measurements associated with one or more reference signals received from the second plurality of wireless communication devices. [C7] Starting the transmission of the reference signal by the first plurality of wireless communication devices is the method according to C1, which is performed in response to a network-based trigger. [C8] Cooperating with the second wireless communication device to establish sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices The method according to C1, further comprising. [C9] The start time for the CoT is based on a backoff time selected from an interval based on (a) a count of the number of reference signals associated with the first plurality of wireless communication devices and (b) a count of the number of reference signals associated with the second plurality of wireless communication devices, the method according to C8. [C10] Independently establishing sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices without cooperating with the second wireless communication device The method according to C1, further comprising. [C11] The start time of the CoT is based on a backoff time selected from an interval based on the count of the number of reference signals associated with the second plurality of wireless communication devices, the method according to C10. [C12] Determining a first duration for transmitting a reference signal by the first plurality of wireless communication devices Determining a second duration for transmitting a reference signal by the second plurality of wireless communication devices Before starting the transmission of the reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group, confirming that the first duration of the transmission of the reference signal is less than the second duration of the transmission of the CoT-reference signal The method according to C1, further comprising. [C13] Performing a successful clear channel assessment (CCA) before starting the transmission of the reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group The method according to C12, further comprising. [C14] The reference signal is the method according to C1, which supports round-trip time (RTT) measurements between (a) at least one wireless communication device among the first plurality of wireless communication devices and (b) at least one wireless communication device among the second plurality of wireless communication devices. [C15] communicating with the second wireless communication device using a separate channel, The method according to C1, further comprising. [C16] The method according to C15, wherein the separate channel is arranged within an advanced road traffic system (ITS) frequency band. [C17] The method according to C1, wherein the sidelink channel is arranged within an unlicensed spectrum. [C18] A first wireless communication device in a wireless communication network, a wireless transceiver, a memory, a processor communicatively coupled to the wireless transceiver and the memory, wherein the processor uses the wireless transceiver to transmit a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; uses the wireless transceiver to receive a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, and the CoT comprises a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal; A first wireless communication device configured to start transmitting a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group. [C19] The processor in the first wireless communication device, using a first one of the additional transmission opportunities within the CoT associated with the second positioning group, to send a first reference signal in an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices; The first wireless communication device according to C18, configured to start the transmission of the reference signal by the first plurality of wireless communication devices. [C20] The processor is Before sending the first reference signal, broadcast a group association broadcast message that specifies the transmission order for the ordered sequence of reference signals to be sent from the first plurality of wireless communication devices. The first wireless communication device according to C19, further configured to perform the above. [C21] The processor is In response to a sensor-based trigger, start the transmission of the reference signal by the first plurality of wireless communication devices. The first wireless communication device according to C18, further configured to perform the above. [C22] The sensor-based trigger is the first wireless communication device according to C21, based on the frequency of received reference signals from the second plurality of wireless communication devices. [C23] The sensor-based trigger is the first wireless communication device according to C21, based on one or more received power measurements associated with one or more reference signals received from the second plurality of wireless communication devices. [C24] The processor is In response to a network-based trigger, start the transmission of the reference signal by the first plurality of wireless communication devices. The first wireless communication device according to C18, further configured to perform the above. [C25] The processor is Cooperate with the second wireless communication device to establish sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices. The first wireless communication device according to C18, further configured to perform the above. [C26] The start time for the CoT is based on a backoff time selected from an interval based on (a) the count of the number of reference signals associated with the first plurality of wireless communication devices and (b) the count of the number of reference signals associated with the second plurality of wireless communication devices. The first wireless communication device according to C25. [C27] The processor is Independently establish sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices without cooperating with the second wireless communication device. The first wireless communication device according to C18, further configured to perform [C28] The first wireless communication device according to C27, wherein the start time of the CoT is based on a backoff time selected from intervals based on counting the number of reference signals associated with the second plurality of wireless communication devices. [C29] The processor Determining a first duration for transmission of a reference signal by the first plurality of wireless communication devices; Determining a second duration for transmission of a reference signal by the second plurality of wireless communication devices; Using the additional transmission opportunity within the CoT associated with the second positioning group, before starting the transmission of the reference signal by the first plurality of wireless communication devices, confirming that the first duration of the transmission of the reference signal is less than the second duration of the transmission of the CoT-reference signal; The first wireless communication device according to C18, further configured to perform [C30] The processor Performing a successful clear channel assessment (CCA) before starting the transmission of the reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group; The first wireless communication device according to C29, further configured to perform [C31] The first wireless communication device according to C18, wherein the reference signal supports round-trip time (RTT) measurement between (a) at least one wireless communication device in the first plurality of wireless communication devices and (b) at least one wireless communication device in the second plurality of wireless communication devices. [C32] The processor Communicating with the second wireless communication device using a separate channel; The first wireless communication device according to C18, further configured to perform [C33] The first wireless communication device according to C32, wherein the separate channel is arranged within an advanced road traffic system (ITS) frequency band. [C34] The first wireless communication device according to C18, wherein the sidelink channel is arranged within an unlicensed spectrum. [C35] A first wireless communication device in a wireless communication network, Means for transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device Means for receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal, and means for starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group A first wireless communication device, comprising [C36] A non-transitory computer-readable medium storing instructions for execution by one or more processing units Transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device Receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, wherein the second positioning group is associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal Starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group A non-transitory computer-readable medium comprising instructions for performing

Claims

1. A method for device location estimation, in a first wireless communication device, transmitting a first group formation broadcast message associated with a first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; receiving a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising a transmission opportunity configured to be used by the second plurality of wireless communication devices to communicate a reference signal; starting transmission of a reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group; A method comprising the above.

2. Said starting the transmission of the reference signal by the first plurality of wireless communication devices comprises, in the first wireless communication device, sending a first reference signal in an ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, using a first one of the additional transmission opportunities within the CoT associated with the second positioning group; The method according to claim 1, comprising the above.

3. Further comprising, in the first wireless communication device, broadcasting a group association broadcast message specifying an order of transmission for the ordered sequence of reference signals to be sent from the first plurality of wireless communication devices, before sending the first reference signal; The method according to claim 2, further comprising the above.

4. The method according to claim 1, wherein said starting the transmission of the reference signal by the first plurality of wireless communication devices is carried out in response to a sensor-based trigger.

5. The sensor-based trigger is based on the frequency of the received reference signal from the second plurality of wireless communication devices, or the sensor-based trigger is based on one or more received power measurements associated with one or more reference signals received from the second plurality of wireless communication devices, the method according to claim 4.

6. Said starting of said transmission of said reference signal by the first plurality of wireless communication devices is carried out in response to a network-based trigger, or the sidelink channel is arranged within an unlicensed spectrum, the method according to claim 1.

7. Cooperating with the second wireless communication device to establish sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices, further comprising, preferably, The start time for the CoT is based on a backoff time selected from intervals based on (a) a count of the number of reference signals associated with the first plurality of wireless communication devices and (b) a count of the number of reference signals associated with the second plurality of wireless communication devices, the method according to claim 1.

8. Independently establishing sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices without cooperating with the second wireless communication device, further comprising, preferably, The start time for the CoT is based on a backoff time selected from intervals based on a count of the number of reference signals associated with the second plurality of wireless communication devices, the method according to claim 1.

9. Determining a first duration for transmission of a reference signal by the first plurality of wireless communication devices, Determining a second duration for transmission of a reference signal by the second plurality of wireless communication devices, Confirming that the first duration of transmission of the reference signal is less than the second duration of transmission of the CoT-reference signal before starting the transmission of the reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group, further comprising, the method according to claim 1.

10. Performing a successful Clear Channel Assessment (CCA) before starting the transmission of the reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group. The method according to claim 9, further comprising. **Claim 11** The reference signal supports round-trip time (RTT) measurements between (a) at least one wireless communication device among the first plurality of wireless communication devices and (b) at least one wireless communication device among the second plurality of wireless communication devices. The method according to claim 1. **Claim 12** Communicating with the second wireless communication device using a separate channel. Further comprising, preferably, The separate channel is arranged within an Advanced Road Traffic System (ITS) frequency band. The method according to claim 1. **Claim 13** A first wireless communication device in a wireless communication network, A wireless transceiver, A memory, A processor communicatively coupled to the wireless transceiver and the memory, Comprising, the processor is Transmitting, using the wireless transceiver, a first group formation broadcast message associated with a first positioning group comprising the first plurality of wireless communication devices including the first wireless communication device. Receiving, using the wireless transceiver, a second group formation broadcast message associated with a second positioning group comprising a second plurality of wireless communication devices including a second wireless communication device. The second positioning group is associated with a Channel Occupancy Time (CoT) in a sidelink channel. The CoT comprises a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal. A first wireless communication device configured to start the transmission of the reference signal by the first plurality of wireless communication devices using an additional transmission opportunity within the CoT associated with the second positioning group. **Claim 14** The processor is further configured to implement the method according to any one of claims 2 to 12, and is a first wireless communication device according to claim 13.

15. A non-transitory computer-readable medium storing instructions for execution by one or more processing units, the instructions comprising instructions for performing the method according to any one of claims 1 to 12.

Images