Low latency opportunistic channel occupancy time sharing

Abstract

Aspects relate to group-based reference signal broadcasting in a wireless communication network. A first wireless communication device can transmit a first group formation broadcast message associated with a first positioning group, the first positioning group including a first plurality of wireless communication devices including the first wireless communication device. The first wireless communication device can receive a second group formation broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices including a second wireless communication device. The second positioning group can be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT can include transmission opportunities configured to be used by the second plurality of wireless communication devices for communicating reference signals. The first wireless communication device can 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

[0001] BACKGROUND

[0002] TECHNICAL FIELD

[0003] The technology discussed below relates generally to location estimation for wireless communication devices. More specifically, the technology discussed relates to location estimation using sidelink communications.

[0004] BACKGROUND

[0005] Wireless communications can be facilitated among various devices in various configurations. In one configuration, a cellular network can enable user equipment (UEs) 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 can signal directly with each other, rather than via an intermediate base station or cell. For example, D2D communications can utilize sidelink signaling to facilitate direct communications among UEs. In some sidelink scenarios, UEs can further communicate in a cellular network, generally under the control of a base station. Thus, UEs can be configured for uplink and downlink signaling via a base station, and further for sidelink signaling directly between UEs without transmission through a base station.

[0006] One example of sidelink wireless communications is vehicle-to-everything (V2X) communications. V2X communications involve 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. V2X systems enable vehicles 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 driving experience of the vehicle, increase vehicle safety, and support autonomous vehicles. V2X communications are described herein by way of example only. Sidelink communications can involve other types of devices and communication interactions. For example, sidelink communications can be used for interactions between smartphones (e.g., smartphone-to-smartphone), industrial internet of things (IIOT) devices (e.g., IIOT-to-IIOT), and / or other types of communications.

[0007] While there are many benefits to the use of sidelink communications, the decentralized nature of sidelink communications presents challenges to the management of signaling involving different entities, given the ability to communicate directly without an intermediate base station.

[0008] BRIEF OVERVIEW

[0009] The following presents a summary of one or more aspects of the present disclosure to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the present disclosure, and is not intended to identify key or critical elements of the present disclosure or to delineate the scope of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in a form that is brief, so as to provide a conceptual introduction to one or more aspects of the present disclosure for the purpose of

[0010] In one example, a method of wireless communication is disclosed. The method includes transmitting a first group formation broadcast message associated with a first positioning group, the first positioning group including 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, the second positioning group including a second plurality of wireless communication devices including the second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel. The CoT can include a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal. The method further includes initiating 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.

[0011] 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, the first positioning group including 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, the second positioning group including a second plurality of wireless communication devices including the second wireless communication device. The second positioning group can be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT can include a transmission opportunity configured to be used by the second plurality of wireless communication devices for communicating a reference signal. The processor is configured to initiate 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.

[0012] 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, the first positioning group including 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, the second positioning group including a second plurality of wireless communication devices including a second wireless communication device. The second positioning group can be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT can include 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 initiating 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.

[0013] Another example provides a non-transitory computer-readable medium having stored therein instructions for execution by one or more processing units. The non-transitory computer-readable medium includes instructions for transmitting a first group formation broadcast message associated with a first positioning group, the first positioning group including a first plurality of wireless communication devices including the first wireless communication device. The non-transitory computer-readable medium further includes instructions for receiving a second group formation broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices including a second wireless communication device. The second positioning group can be associated with a channel occupancy time (CoT) in a sidelink channel. The CoT can include 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 includes instructions for initiating 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.

[0014] These and other aspects will become more fully understood upon reading the following detailed description in conjunction with the accompanying drawings. Other aspects, features, and embodiments will become apparent to those of ordinary skill in the art, upon reviewing the following description. While certain features are discussed in the context of certain embodiments and figures, other embodiments can also exhibit the same or similar features. In other words, although some embodiments can be discussed with respect to particular features, one or more of such features can be used in accordance with the various embodiments discussed herein. In a similar manner, although example embodiments can be discussed in the context of devices, systems, or methods, other implementations can also exhibit the same or similar features. It is to be understood that other specific arrangements of parts and / or methods can be utilized, and that the scope of the disclosure is not limited to the specific arrangements and methods described herein. BRIEF DESCRIPTION OF DRAWINGS

[0016] Aspects of the disclosure are illustrated by way of example. In the drawings, like reference numbers indicate similar elements.

[0017] FIG. 1 is a diagram illustrating an example of a wireless radio access network according to some aspects.

[0018] FIG. 2 is a diagram illustrating an example of a wireless communication network employing sidelink communication according to some aspects.

[0019] FIG. 3 is a signaling diagram illustrating an example of sidelink-based positioning according to some aspects.

[0020] FIG. 4 is a diagram illustrating an example of transmission of positioning reference signals (PRS) in a sidelink communication network according to some aspects.

[0021] FIG. 5 is a signaling diagram illustrating an example of positioning group formation for group-based PRS broadcast according to some aspects.

[0022] 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.

[0023] FIG. 7 is a diagram illustrating an example of a group formation broadcast message transmitted by a group initiator according to some aspects.

[0024] FIG. 8 is a diagram illustrating an example of a group formation broadcast message transmitted by a group responder according to some aspects.

[0025] FIG. 9 is a diagram illustrating an example of a group association broadcast message transmitted by a group initiator according to some aspects.

[0026] FIG. 10 is a diagram illustrating an example of positioning group formation according to some aspects.

[0027] FIG. 11 is a diagram illustrating an example of group-based PRS broadcast according to some aspects.

[0028] FIG. 12 An example of an arrangement of devices belonging to two PRS broadcast positioning groups in a scenario suitable for opportunistic CoT sharing is illustrated.

[0029] FIG. 13 is a timing diagram illustrating an example of an opportunity for CoT sharing between two PRS broadcast positioning groups.

[0030] FIG. 14 An attempt at opportunistic sharing of CoT is illustrated.

[0031] FIG. 15 An attempt at opportunistic sharing of CoT that fails due to insufficient transmission time is illustrated.

[0032] FIG. 16 An attempt at opportunistic sharing of CoT that fails due to a failed clear channel assessment (CCA) is illustrated.

[0033] FIG. 17 is a block diagram illustrating an example of a hardware implementation for a wireless communication device 1700 employing a processing system.

[0034] FIG. 18 is a flow diagram 1800 illustrating an example method for group-based PRS broadcasting, in accordance with some aspects.

[0035] DETAILED DESCRIPTION

[0036] Several illustrative embodiments will now be described with reference to the drawings, which form a part of this application. While these embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, other embodiments may be employed, and not all of the described embodiments are necessary to practice the disclosure. For example, the described embodiments can be implemented in different software modules or combined software-digital hardware implementations. Changes in, or substitutions of, various

[0037] The detailed description set forth below, in connection with the appended drawings and embodiments described herinin, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. Rather, the detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without

[0038] While aspects and embodiments are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases can come about in many different arrangements and scenarios. Innovations described herein can be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, embodiments and / or uses can come about via integrated chip embodiments, and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / purchasing devices, medical devices, AI-enabled devices, etc.). Some examples can be or can include, for example, a machine-to-machine (M2M) or Machine Type Communication (MTC) use case where the innovations described herein are implemented via one or more M2M or MTC devices. These devices can include sensors, gauges, monitors, or any combination of hardware and / or software that can communicate over a wireless, wired, or optical medium. Some examples can be or include, for example, a vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-everything (V2X) implementation, where the innovations described herein are implemented via one or more vehicles, infrastructure, or a combination of both. Embodiments and / or uses can come about via other use cases and can include one or more of these examples. The innovations described herein are

[0039] The various concepts presented throughout this disclosure can be implemented across a wide variety of telecommunications systems, network architectures, and communication standards. Referring now to FIG. 1 By way of illustrative example, but not limitation, a schematic illustration of a radio access network 100 is provided. The RAN 100 can implement any suitable wireless communication technology or technologies to provide radio access. As one example, the RAN 100 can operate according to 3rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN 100 can operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as LTE. The 3GPP refers to this hybrid RAN as a Next Generation RAN, or NG-RAN. Of course, many other examples can be utilized within the scope of the present disclosure.

[0040] The geographic region covered by the radio access network 100 can be divided into a number of cellular regions (cells), each of which can be uniquely identified by a cell identifier (ID) broadcast in the cell by an access point or base station. The cells can be of an FDD, TDD, or mixed FDD / TDD types. FIG. 1The macro cells 102, 104 and 106, and the small cell 108 are illustrated as each including one or more sectors (not shown). A sector is a sub-area of a cell. All sectors within a cell are served by the same base station. Radio links within a sector can be identified by a single logical identity belonging to that sector. In a cell partitioned into sectors, multiple sectors within a cell can be formed by an antenna group, where each antenna is responsible for communication to UEs in a part of the cell.

[0041] Generally, respective base stations (BSs) serve the respective cells. Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception to and from UEs in one or more cells. A BS can also be referred to by those skilled in the art as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B (NB), an evolved Node B (eNB), a Next Generation Node B (gNB), or some other suitable terminology.

[0042] In FIG. 1 two base stations 110 and 112 are illustrated in the cells 102 and 104; and a third base station 114 is illustrated as controlling a remote radio head (RRH) 116 in the cell 106. That is, a base station can have integrated antennas, or can be connected by feeders to antennas or RRHs. In the illustrated example, the cells 102, 104 and 106 can be referred to as macro cells because the base stations 110, 112 and 114 support cells with large sizes. Further, a base station 118 is illustrated in a small cell 108 (e.g., a microcell, a picocell, a femtocell, a home base station, a home NodeB, a home evolved NodeB, etc.) that can overlap with one or more macro cells. In this example, the cell 108 can be referred to as a small cell because the base station 118 supports a cell with a relatively small size. Cell size setting can be done according to system design and component constraints. It is to be understood that the radio access network 100 can include any number of wireless base stations and cells. Further, a relay node can be deployed to extend the size or coverage area of a given cell. The base stations 110, 112, 114, 118 provide wireless access points to a core network for any number of mobile

[0043] FIG. 1 Further included is a quadcopter or drone 120, which can be configured to function as a base station. That is, in some examples, a cell can not necessarily be stationary, and the geographic area of a cell can move according to the position of a mobile base station, such as the quadcopter 120.

[0044] Generally, a base station can include a backhaul interface for communication with a backhaul portion of a network (not shown). The backhaul can provide a link between a base station and a core network (not shown), and in some examples, can provide interconnection between respective base stations. The core network can be part of a wireless communication system and can be independent of the radio access technology used in the radio access network. Various types of backhaul interfaces can be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network.

[0045] The RAN 100 is illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus is commonly referred to as user equipment (UE) in standards and specifications promulgated by the third generation partnership project (3 GPP), but can also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE can be an apparatus that provides access to a network service for a user.

[0046] Within the present document, a "mobile" device need not have a mobile capability, and can be static. The term mobile device or mobile equipment refers to a broad variety of devices and technologies. For example, some non-limiting examples of a mobile device include a mobile device, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC), a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA), and a vast range of embedded systems, e.g., corresponding to "Internet of Things" (IoT). Additionally, a mobile device can be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotic device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and / or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, etc. A mobile device additionally can be a digital home or smart home device, such as a home audio, video, and / or multimedia device, a domestic appliance, a vending machine, a smart lighting device, a home security system, a smart meter, etc. A mobile device can additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling / monitoring traffic, power, utility, etc. (e.g., smart grid), an industrial automation and / or enterprise device, a logistics controller / monitor, agricultural equipment, etc. Still further, a mobile device can provide for connected medicine and remote healthcare, i.e., health care at a distance. Telehealth devices can include telehealth monitoring devices and telehealth administration devices, whose communication can be given preferential treatment, e.g., in form of prioritized access for critical service data transfer and / or relevant QoS for critical service data transfer over other types of information.

[0047] Within the RAN 100, a cell can include UEs that can be in communication with one or more sectors of each cell. For example, UEs 122 and 124 can be in communication with base station 110; UEs 126 and 128 can be in communication with base station 112; UEs 130 and 132 can be in communication with base station 116 via RRH 114; UE 134 can be in communication with base station 118; and UE 136 can be in communication with mobile base station 120. Here, each base station 110, 112, 114, 118, and 120 can be configured as an access point to a core network (not shown) for all the UEs in the corresponding cell. In another example, a mobile network node (e.g., quadcopter 120) can be configured to function as a UE. For example, quadcopter 120 can operate within cell 102 by communicating with base station 110.

[0048] Wireless communication between a RAN 100 and a UE (e.g., UE 122 or 124) can be described as utilizing an air interface that includes one or more physical channels. Transmissions from a base station (e.g., base station 110) to one or more UEs (e.g., UEs 122 and 124) can be referred to as downlink (DL) transmission. In accordance with certain aspects of the present disclosure, the term downlink can refer to a point-to-multipoint transmission from a scheduling entity (described further below; e.g., a base station 110) to a set of one or more subordinate entities (described further below; e.g., UEs 122 and 124). Another way of describing this approach is to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE 122) to a base station (e.g., base station 110) can be referred to as uplink (UL) transmissions. In accordance with further aspects of the present disclosure, the term uplink can refer to a point-to-point transmission from a subordinate entity (described further below; e.g., UE 122) to a scheduling entity (described further below; e.g., base station 110).

[0049] For example, a DL transmission can include unicast or broadcast transmissions 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), while an UL transmission can include transmissions of control information and / or traffic information originating at a UE (e.g., UE 122). Further, uplink and / or downlink control information and / or traffic information can be partitioned in time into frames, subframes, slots, and / or symbols. As used herein, a symbol can refer to a time unit of one resource element (RE) per subcarrier in an orthogonal frequency division multiplexing (OFDM) waveform. A slot can carry 7 or 14 OFDM symbols. A subframe can refer to a duration of 1 ms. Multiple subframes or slots can be grouped together to form a single frame or radio frame. Of course, these definitions are not required and any suitable scheme can utilize any appropriate organization of waveform and various time divisions of the waveform can have any suitable duration.

[0050] The air interface in the RAN 100 can utilize one or more multiplex and multiple access algorithms to enable simultaneous communication of the various devices. For example, 5G NR specifications provide multiple access for UL or reverse link transmissions from a plurality of UEs 122 and 124 to a base station 110, and utilizes orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (hereinafter also referred to as CP-OFDM) for DL or forward link transmissions from the base station 110 to a plurality of UEs 122 and 124. Additionally, for UL transmissions, 5G NR specifications provide support for discrete Fourier transform-spread-OFDM (DFT-s-OFDM) with a CP (also referred to as single-carrier FDMA (SC-FDMA)). However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes and can be implemented, for example, with 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 schemes. Further, multiplexing for DL transmissions from the base station 110 to a UE 122 and 124 can be provided utilizing 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 schemes.

[0051] Further, the air interface in the RAN 100 can utilize one or more duplex algorithms. Duplex refers to a point-to-point communication link in which both endpoints can communicate with one another. Full duplex means both endpoints can communicate with one another simultaneously. Half duplex means only one endpoint in the link can send information to the other at a time. In a wireless link, a full duplex channel generally relies on physical isolation of a transmitter and receiver, and suitable interference cancellation technologies. Full duplex emulation is typically achieved by utilizing frequency or time division duplex (FDD or TDD). In FDD, transmissions in different directions operate at different carrier frequencies. In TDD, transmissions in different directions operate at the same carrier frequency, but are separated by time. That is, at some times the communication link is dedicated to one direction of transmission, while at other times the link is dedicated to the other direction of transmission, where the direction can change very rapidly, such as several times per time slot.

[0052] In the RAN 100, the ability for a UE to communicate while moving between different locations is referred to as mobility. The various physical channels established for the UE can be released and / or setup under the control of the access and mobility management function (AMF) 130 in the core network 106. In some scenarios, the AMF can include a security context management function (SCMF) and a security anchor function (SEAF). The SCMF can manage the security context for both control and user planes, in whole or in part. The SEAF can perform authentication.

[0053] In some examples, the RAN 100 can implement mobility and handover (i.e., transfer of a UE’s connection from one radio channel to another). For example, during a call with a scheduling entity, or at any other time, a UE can monitor various parameters of the signal from its serving cell and various parameters of neighboring cells. Depending on the quality of these parameters, the UE can maintain communication with one or more neighboring cells. During this time, if the UE moves from the area served by one cell to another cell, or if the signal quality from a neighboring cell exceeds that of the serving cell for a given amount of time, the UE can hand over or hand in from the serving cell to the neighboring (target) cell. For example, a UE 124, illustrated as a vehicle, but which can use any suitable form of UE, can move from the geographic area corresponding to its serving cell 102 to the geographic area corresponding to a neighbor cell 106. When the signal strength or quality from the neighbor cell 106 exceeds that of its serving cell 102 for a given amount of time, the UE 124 can transmit a reporting message to its serving base station 110 indicating this condition. In response, the UE 124 can receive a handover command and the UE can undergo handover to cell 106.

[0054] In various implementations, the air interface in the RAN 100 can utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum provides for exclusive use of a portion of spectrum to one or more license holders. Unlicensed spectrum provides for non-exclusive use of a portion of spectrum to any and all compliant wireless

[0055] In some examples, access to the air interface can be scheduled, where a scheduling entity (e.g., a base station) allocates resources (e.g., time-frequency resources) to devices and equipment within its service area or cell for use in communicating. Within the present disclosure, the scheduling entity can be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities. That is, for scheduled communication, a UE or scheduled entity utilizes resources allocated by the scheduling entity.

[0056] A base station is not the only entity that can function as a scheduling entity. That is, in some examples, UEs can function as scheduling entities, scheduling 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 a base station. For example, UE 138 is illustrated communicating with UEs 140 and 142. In some examples, UE 138 is functioning as a scheduling entity or transmitting side link device, and UEs 140 and 142 can be functioning as scheduled entities or receiving side link devices. For example, UE 138 can function as a scheduling entity in a device-to-device (D2D), peer-to-peer (P2P), vehicle-to- everything (V2X), and / or mesh network. In a mesh networking example, UEs 140 and 142 can optionally communicate directly with one another in addition to communicating with the scheduling entity 138.

[0057] In some aspects of the disclosure, two or more UEs (e.g., UEs 126 and 128) within the coverage area of a serving base station 112 can communicate with one another using sidelink signals 127 without the communication being relayed by a 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 communications between UEs 126 and 128. For example, UEs 126 and 128 can communicate sidelink signals 127 within a vehicle-to-everything (V2X) network.

[0058] Two main technologies that can be used by V2X networks include dedicated short-range communications (DSRC) based on the IEEE 802.1 Ip standard and cellular V2X based on LTE and / or 5G (New Radio) standards. Various aspects of the disclosure can relate to New Radio (NR) cellular V2X networks, referred to herein for simplicity as V2X networks. However, it should be understood that the concepts disclosed herein can not be limited to a particular V2X standard, or can refer to sidelink or D2D networks other than V2X networks.

[0059] FIG. 2An example of a wireless communication network 200 configured to support D2D or sidelink communication is illustrated. In some examples, the sidelink communication can include V2X communication. V2X communication involves not only direct wireless information exchange between vehicles (e.g., vehicles 202 and 204) themselves, but also direct wireless information exchange between vehicles 202 / 204 and infrastructure 206 (e.g., a roadside unit (RSU)) such as a streetlight, a building, a traffic camera, a tollbooth, or other stationary object, vehicles 202 / 204 and pedestrians 208, and vehicles 202 / 204 and a cellular network (e.g., base station 210). In some examples, V2X communication can be implemented in accordance with a New Radio (NR) cellular V2X standard defined by 3GPP (Release 15 or 16) or other suitable standard.

[0060] 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 vehicles, and other relevant information that can be used to improve 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, V2X-connected vehicles 202 and 204 can utilize exchanged V2X data to provide in-vehicle collision warnings, road hazard warnings, proximity to emergency vehicle warnings, pre-crash / post-crash warnings and information, emergency braking warnings, forward traffic congestion warnings, lane change warnings, intelligent navigation services, and other similar information. In addition, V2X data received by a V2X-connected mobile device of a pedestrian / bicyclist 208 can be used to trigger a warning sound, vibration, flashing light, etc. in situations where a hazard is imminent.

[0061] V-UEs 202 and 204, or V-UEs 202 or 204 and RSU 206 or a pedestrian UE (P-UE) 208, occur over a sidelink channel 212. The sidelink channel 212 can be used to establish a PC5 interface with or without including a base station (e.g., base station 210) of a wireless network. In examples involving a wireless network, the PC5 interface can be oriented by the wireless network. For example, the wireless network can orient the PC5 interface over a Uu radio interface established between a UE (e.g., V-UEs 202, 204, P-UE 208, etc.) and a radio access network (RAN) (e.g., base station 210) of the wireless network. In some aspects, the sidelink channel 212 can support a Proximity Services (ProSe) PC5 interface. In various aspects of the disclosure, the sidelink channel 212 implementing the PC5 interface can further be used 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.

[0062] ProSe communications can support different operational scenarios, such as in-coverage, out-of-coverage, and partial-coverage. Out-of-coverage refers to a scenario in which UEs (e.g., V-UEs 202 and 204 and P-UE 208) are outside of a coverage area of a base station (e.g., base station 210), but each UE is still configured for ProSe communications. Partial-coverage refers to a scenario in which some of the UEs (e.g., V-UE 204) are outside of a coverage area of the base station 210, while other UEs (e.g., V-UEs 202 and P-UE 208) are in communication with the base station 210. In-coverage refers to a scenario in which UEs (e.g., UEs 214 and 216) are in communication with a base station 210 (e.g., gNB) via a Uu (e.g., cellular interface) connection to receive a ProSe service authorization and provisioning information to support ProSe operations.

[0063] In any of the above operational scenarios, various mobile sidelink devices (e.g., V-UEs 202 and 204, P-UE 208, and other mobile sidelink devices communicating over the sidelink channel 212) can determine their position (e.g., geographic coordinates) in the sidelink network 200 using a sidelink positioning mechanism. To support sidelink positioning, positioning reference signals (PRSs) can be transmitted between RSU 206, V-UEs 202 and 204, and P-UE 208. In some examples, the PRSs can be sequence-based signals and can further be transmitted over an unlicensed spectrum (e.g., ITS band) or a licensed spectrum.

[0064] Depending on the capabilities of the mobile sidelink devices (e.g., V-UEs 202 / 204 and P-UEs 208), a respective position 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 computes its own position in a distributed manner using broadcasted PRS. In SL-a positioning, the RSU 206 or other server in the network computes the position of the mobile sidelink device. In either SL-a positioning or SL-b positioning, the position of a mobile sidelink device (e.g., V-UE 202) can be determined based on round-trip times (RTTs) between the mobile sidelink device (e.g., V-UE 202) and other sidelink devices (e.g., RSU 206). Such RTT measurements are indicative of the distance between the two devices. With several such RTT measurements (and corresponding distances), multilateration can be used to determine the position of the mobile sidelink device. For example, V-UE 202 can take 3 RTT measurements with 3 different RSUs. A first RTT measurement can be indicative of the distance between V-UE 202 and a first RSU. A second RTT measurement can be indicative of the distance between V-UE 202 and a second RSU. A third RTT measurement can be indicative of the distance between V-UE 202 and a third RSU. If the positions of the three RSUs are known, the position of V-UE 202 can be determined through multilateration, e.g., using the three distances as radii of circles centered at the known RSU positions.

[0065] FIG. 3 is a signaling diagram illustrating an example of sidelink (SL-b) based positioning according to some aspects. In the example shown, a V-UE 304 is shown communicating with an RSU 302 over a sidelink channel. In some examples, the sidelink channel can comprise an unlicensed spectrum (e.g., an ITS band). The V-UE 304 may, for example, correspond to any of the V-UEs 202 or 204 shown in FIG. 2. Additionally, the RSU 302 may, for example, correspond to the RSU 206 shown in FIG. 2. It will be appreciated that the signaling diagram shown in FIG. 3 can be implemented between any two wireless communication devices (e.g., RSUs, V-UEs, P-UEs, etc.), and can further be implemented between more than two wireless communication devices (e.g., between a V-UE 304 and multiple RSUs 302, 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). FIG. 3 The example shown in FIG. 3 can be implemented in accordance with any of the aspects described herein. For example, the example shown in FIG. 3 can be implemented in accordance with the example shown in FIG. 2. Additionally, the example shown in FIG. 3 can be implemented in accordance with any of the examples shown in FIGS. 4-7. FIG. 2 FIG. 2 FIG. 3 The signaling diagram shown in FIG. 3 can be implemented between any two wireless communication devices (e.g., RSUs, V-UEs, P-UEs, etc.), and can further be implemented between more than two wireless communication devices (e.g., between a V-UE 304 and multiple RSUs 302, 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).

[0066] FIG. 3 ​​An RTT measurement is illustrated. The RTT measurement involves the exchange of PRS signals 306 and 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, completing the round trip. In FIG. 3 In the example shown, time is illustrated in the vertical direction to depict the transmission and reception of signals over time. For example, at 306, RSU 302 broadcasts a first PRS over a sidelink channel at an initial time (ti). The first PRS can include, for example, a PRS sequence. The PRS sequence can be a wideband random sequence broadcast over an unlicensed band. In some examples, the PRS can include a sequence identifier (ID) that identifies the PRS sequence. The first PRS can be received at V-UE 304 at a second time (t2) after ti. At 308, V-UE 304 broadcasts a second PRS over the sidelink channel at a third time (t3), which is received at RSU 302 at a fourth time (t4). Thus, the RTT measurement includes a first propagation time (t2-ti) and a second propagation time (t4-t3). That is, RTT = (t2-ti) + (t4-t3), which can be rearranged as RTT = (t4-ti) - (t3-t2). V-UE 304 can determine the time difference (t3-t2) locally. RSU 302 can determine the time difference (t4-ti) locally. These two time differences can be combined at RSU 302, V-UE 304, or another location to calculate the RTT.

[0067] For example, if the RTT is to be calculated at V-UE 304 (e.g., SL-b positioning), V-UE 304 can determine the time difference (t3-t2) locally and receive PRS message 310 from RSU 302 that includes the time difference (t4-ti) as a payload. The PRS message can also include other information. As FIG. 3 As shown in FIG. 3, RSU 302 transmits a PRS measurement message to V-UE 304 over a sidelink channel that includes various positioning information. For example, the positioning information included in the payload of the PRS measurement message can include the time of departure (ti) of the first PRS and the time of arrival (t4) of the second PRS (either individually as ti and t4 or as the time difference (t4-ti)). Other positioning information can include the PRS sequence ID, the clock error noise standard deviation of RSU 302, the clock drift standard deviation of RSU 302, the location of RSU 302, and other suitable information. The PRS measurement message can further include respective UE IDs (e.g., Layer 2 (L2) medium access control (MAC) IDs) of RSU 302 and V-UE 304.

[0068] Accordingly, at 312, the V-UE 304 can calculate the RTT based on the positioning information included in the PRS measurement message, the time of arrival of the first PRS (t2), the time of departure of the second PRS (t3), and the clock error of the V-UE 304 (e.g., clock drift standard deviation and clock error noise standard deviation) determined using its own Kalman filter. For example, if a multi-RTT measurement is made, the nth RTT can be expressed as:

[0069]

[0070] where v 光 is the speed of light, a is an adjustment parameter based on the clock error of the RSU 302 and the V-UE 304, r is the location of the RSU 302, and x is unknown.

[0071] In an example utilizing SL-a positioning, the V-UE 304 can transmit a PRS measurement message to the RSU 302 including, for example, the time of arrival of the first PRS (t2), the time of departure of the second PRS (t3), and other positioning information such 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).

[0072] When using Positioning Reference Signals (PRS) as an example to illustrate various aspects, different types of reference signals can be used. For example, Sounding Reference Signals (SRS) can be used instead. Generally, SRS are transmitted by a user equipment (UE) in the uplink direction and used by an eNodeB to estimate the uplink channel quality over a wider bandwidth. The eNodeB can use the channel quality information for uplink frequency selective scheduling. SRS is just one alternative. Other types of reference signals can be used instead of PRS as mentioned herein.

[0073] FIG. 4 is a diagram illustrating an example of transmission of a Positioning Reference Signal (PRS) in a sidelink communication network 400 in accordance with some aspects. In FIG. 4 In the example shown, a V-UE 402 is shown in wireless communication with a plurality of RSUs 404, 406, and 408 over a sidelink channel. In some examples, the sidelink channel can include an unlicensed spectrum (e.g., ITS band). The V-UE 402 may, for example, correspond to FIG. 2 and / or FIG. 3 any of the V-UEs shown in FIG. 13. Additionally, the RSUs 404, 406, and 408 may, for example, correspond to FIG. 2 and / or FIG. 3Any of the RSUs shown in FIG. 4. It should be further understood that, in some examples, the V-UE 402 can be a P-UE or other mobile sidelink device. Additionally, one or more of the RSUs 404, 406, and 408 can be other V-UEs, P-UEs, and / or other mobile sidelink devices.

[0074] FIG. 4 The PRS communications between the V-UE 402 and the RSUs 404, 406, and 408 are further illustrated over time. For example, a first PRS 410 (labeled as signal 1) can be broadcast from the RSU 404, followed by a second PRS 412 (labeled as signal 2) broadcast from the RSU 406, followed by a third PRS 414 (labeled as signal 3) broadcast by the RSU 408, followed by a fourth PRS 416 (labeled as signal 4) broadcast by the V-UE 402. Upon receiving the fourth PRS 416 by each of the RSUs 404, 406, and 408, each of the RSUs 404, 406, and 408 can then transmit respective PRS measurement signals 418, 420, and 422 (labeled as signals 5, 6, and 7) to the V-UE 402. As discussed above, the V-UE 402 can then calculate its position based on the PRS measurement signals 418, 420, and 422, the time of departure of the fourth PRS 416, and the respective times of arrival of the other PRSs 410, 412, and 414 at the V-UE 402. For example, PRS 410 and PRS 416 (labeled as signals 1 and 4), along with PRS measurement signal 418 (labeled as signal 5) can constitute a first RTT measurement. PRS 412 and PRS 416 (labeled as signals 2 and 4), along with PRS measurement signal 420 (labeled as signal 6) can constitute a second RTT measurement. PRS 414 and PRS 416 (labeled as signals 3 and 4), along with PRS measurement signal 422 (labeled as signal 7) can constitute a third RTT measurement. After obtaining the three RTT measurements, the V-UE 402 can determine its own position by performing trilateration using the known positions of the RSUs 404, 406, and 408.

[0075] The efficiency and accuracy of SL-b positioning (or SL-a positioning) depends on the latency (e.g., time gap 424) between the PRSs 410, 412, 414, and 416. When listen-before-talk (LBT) or another channel sensing mechanism is implemented to access the sidelink channel, the availability of the sidelink channel to each wireless communication device (e.g., V-UE 402, RSU 404, RSU 406, and RSU 408) can vary, affecting the PRS latency.

[0076] Accordingly, in various aspects of the disclosure, wireless communication devices (e.g., V-UEs, P-UEs, RSUs, etc.) communicating over a sidelink channel in a sidelink wireless communication network can be grouped into one or more positioning groups. Within each positioning group, a respective order of the wireless communication devices in the positioning group can be designated. The wireless communication devices in a particular positioning group (e.g., positioning group members) can then communicate PRSs among themselves over 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) within which each wireless communication device in the positioning group can broadcast PRSs in the positioning group and communicate PRS measurement messages to other positioning group members, thereby reducing PRS latency.

[0077] In some examples, the wireless communication devices can be configured to form a positioning group by broadcasting group formation broadcast messages over the sidelink channel. One of the wireless communication devices in each positioning group can be considered an initiator device that initiates the positioning group, while the other wireless communication devices in the positioning group can be considered responder devices. For example, an initiator device can broadcast an initiator (or first) group formation broadcast message to form a positioning group. Other wireless communication devices that receive the initiator group formation broadcast message can then respond with subsequent responder group formation broadcast messages that identify the initiator device and other responder devices that previously responded to the first group formation broadcast message. Accordingly, the responder group formation broadcast messages can build upon each other such that the last responder group formation broadcast message identifies the initiator device and all other responder devices in the positioning group.

[0078] The initiator device can then determine an order of the wireless communication devices in the positioning group from each of the responder group formation broadcast messages and transmit (e.g., broadcast or groupcast) a group association broadcast message that identifies the members of the positioning group and their order. The initiator device can then reserve the sidelink channel for a CoT based on the number of wireless communication devices in the positioning group and broadcast a first PRS during the CoT. The responder devices can then each broadcast their respective PRSs within the CoT based on the order of the wireless communication devices. Accordingly, the respective transmission timing of each PRS from each wireless communication device in the positioning group can be determined according to the order.

[0079] As discussed above, messages such as group formation messages (GFM) or group association messages (GAM) can be transmitted in the form of broadcast messages. Such broadcast messages can be "broadcast" or "groupcast" to various devices. In this sense, "broadcast" refers to transmission to two or more devices. All devices within range of the broadcast signal can be able to receive the message. In contrast, "groupcast" refers to reception by only a subset of devices within range of the signal. For example, a signal associated with a groupcast message can reach a set of devices ("A"). However, the groupcast can be intended only for and decodable only by a subset of devices ("B") within the set "A."

[0080] In some examples, LBT can be used to reserve a sidelink channel. For example, an initiating device (e.g., RSU, V-UE, 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 the energy to an energy detection (ED) threshold. For example, if the energy detected on the channel is at or below the ED threshold level (e.g., indicating that the channel is relatively talk-less), the initiating device can reserve the sidelink channel for the CoT and transmit a first PRS.

[0081] Different types of LBT procedures can be defined according to different categories. For example, Category 1 (Cat-1) LBT specifies no LBT is used. Cat-2 LBT specifies LBT with no random backoff is used. Cat-3 LBT specifies LBT with random backoff with a fixed size contention window is used. Cat-4 LBT specifies LBT with random backoff with a variable size contention window is used. In an aspect, the initiating device can implement Cat-4 LBT to reserve the CoT for all positioning group members. Thereafter, the responding devices can implement Cat-2 LBT to broadcast their PRS.

[0082] In some examples, wireless communication devices in a sidelink communication network can be classified as anchor devices or non-anchor devices. Anchor devices can include, for example, RSUs (e.g., RSUs 404, 406, and 408), along with V-UEs (e.g., V-UE 402) and P-UEs that include accurate internal positioning devices (e.g., GPS or other navigation systems). Non-anchor devices can include, for example, V-UEs and P-UEs that do not include accurate internal positioning devices. Thus, anchor devices can be considered to have a known location based on location accuracy (e.g., an allowed accuracy tolerance or bias), and non-anchor devices can be considered to have an unknown location based on location accuracy.

[0083] In some aspects, an initiator device can comprise an anchor device, while a responder device can comprise at least a non-anchor device. In some examples, an anchor device that receives a group formation broadcast message from another anchor initiator device can become a responder device to the initiator device, or become an initiator device of another positioning group. For example, an anchor device can compare a reference signal received power (RSRP) of a received group formation broadcast message from another anchor initiator device to determine whether to become a responder device to the other initiator 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 can become a responder device. Otherwise, if the RSRP of the received group formation broadcast message is less than the threshold, the anchor device can become an initiator device of another positioning group. In this example, the other anchor initiator device can be excluded from the positioning group (e.g., the other anchor initiator device can form its own separate positioning group).

[0084] Similarly, for a responder device, if multiple group formation broadcast messages are received from multiple anchor initiator devices, the responder device can select one of the anchor initiator devices and join the positioning group of the selected anchor initiator device (e.g., by transmitting a responder group formation broadcast message that includes the selected anchor initiator device ID). In some examples, each positioning group can be configured with a maximum number of members. If one of the positioning groups has reached the maximum number of members, the responder device can select another positioning group, or can become an initiator if no other positioning group is available. In some examples, a non-anchor device can not receive a group formation broadcast message from any anchor initiator device. In this example, the non-anchor device can become an initiator device to initiate a positioning group for the non-anchor device.

[0085] In some examples, positioning group formation can be performed periodically. For example, a group formation broadcast message associated with a new positioning group can be broadcasted with a periodicity that is less than a periodicity of a PRS cycle (e.g., with a duration that is greater than a periodicity of a PRS cycle) to enable the positioning groups to complete multiple PRS cycles before changing positioning groups. In some examples, a PRS cycle can be 100 ms. In this example, positioning group formation can be performed every 1000 ms.

[0086] For example, positioning group formation can be performed in a time domain in a group phase. The group phase can be followed by a PRS phase that includes one or more PRS cycles. The group phase can further include an initiator sub-phase and a responder sub-phase. An anchor device can transmit an initiator group formation broadcast message within the initiator sub-phase. Responder devices can transmit responder group formation broadcast messages within the responder sub-phase. Additionally, non-anchor devices that do not receive an initiator group formation broadcast message within the initiator sub-phase can transmit an initiator group formation broadcast message within the responder sub-phase. The group phase can further include a second initiator sub-phase after the responder sub-phase, within which initiator devices can transmit a group association broadcast message that identifies members of the positioning group and their order.

[0087] FIG. 5 is a signaling diagram illustrating an example of positioning group formation for group-based PRS broadcast according to some aspects. In the example shown, FIG. 5 In the example shown, an initiator wireless communication device (WCD1) 502 is in wireless communication with responder wireless communication devices 504 and 506 (WCD2 and WCD3, respectively) over a sidelink channel. In some examples, the sidelink channel can include unlicensed spectrum (e.g., ITS spectrum). In other examples, the sidelink channel can include licensed spectrum. The sidelink channel can use LBT or other channel sensing mechanisms for channel access.

[0088] Each of the wireless communication devices 502, 504, and 506 can correspond to any of the RSUs, V-UEs, or P-UEs shown in FIGS. 1, FIG. 2 , 3 and / or 4. In some examples, the initiator wireless communication device 502 (referred to herein for simplicity as the initiator device) can be an anchor device. In other examples, the initiator device 502 can be a non-anchor device in examples where a group formation broadcast message is not received from an anchor device. The responder wireless communication devices 504 and 506 (referred to herein for simplicity as the responder devices) can be non-anchor devices or anchor devices (e.g., if the initiator device 502 is in close proximity to these anchor devices).

[0089] At 508, the initiator device 502 can broadcast (or groupcast) a first group formation broadcast message over a sidelink channel to form a positioning group. At 510, the responder device 504 can broadcast (or groupcast) a second group formation broadcast message over the sidelink channel to join the positioning group. The second group formation broadcast message can include, for example, an initiator ID of the initiator device. At 512, the responder device 506 can broadcast (or groupcast) a third group formation broadcast message over the sidelink channel to join the positioning group. The third group formation can include, for example, the initiator ID of the initiator device and a responder ID of the responder device 504. Each of the first, second, and third group formation messages can further include other device information associated with the transmitting device. Examples of device information can include, but are not limited to, initiator information indicating that the transmitting device is an initiator device of the positioning group, anchor information indicating that 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 a discontinuous reception mode), and a group ID identifying the transmitting device within the positioning group. In some examples, the group ID can be a random number within the group. In other examples, the group ID can be a UE ID (e.g., a MAC ID) of the transmitting device.

[0090] At 514, the initiator device 502 can determine an 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 initiator device 502 can include the responder devices 504 and 506 within the positioning group. The initiator device 502 can then list the initiator device 502 first in the order of wireless communication devices, followed by the other responder devices 504 and 506. The initiator device 502 can use various factors to determine the order of the responder devices 504 and 506. For example, the order of the responder devices 504 and 506 can be determined based on the device information included in the group formation messages. In an example, the order can correspond to a descending order of the responder devices.

[0091] At 516, the initiator device 502 can broadcast or groupcast a group association broadcast message to the responder devices 504 and 506. The group association message can include an initiator ID of the initiator device and a corresponding responder ID of each of the responder devices 504 and 506 listed in the order of wireless communication devices (e.g., descending order).

[0092] At 518, 520, and 522, the initiator device 502 and the responder devices 504 and 506 can each broadcast (or groupcast) a respective PRS based on the order of the wireless communication devices listed in the group association message. For example, the initiator device 502 can broadcast (or groupcast) a first PRS at 518. Then, at 520, the responder device 504 can broadcast a second PRS. Then, at 522, the responder device 506 can broadcast a third PRS. In some examples, the initiator device 502 can implement a class 4 LBT to transmit the first PRS and reserve the sidelink channel for a CoT within which all PRSs (and corresponding PRS measurement messages) can be transmitted. Thereafter, the responder devices 504 and 506 can implement a class 2 LBT to broadcast their PRSs.

[0093] As previously mentioned, while various aspects are illustrated using positioning reference signals (PRS) as an example, different types of reference signals can alternatively be used, such as sounding reference signals (SRS) or other types of signals.

[0094] FIG. 6 is a diagram illustrating an example of a time domain allocation for positioning group formation and group-based PRS broadcasting according to some aspects. In FIG. 6 In the illustrated example, the sidelink channel can be time divided into group phases (two of which, 602a and 602b, are illustrated for simplicity) and PRS phases (one of which, 604, is illustrated for simplicity). The PRS phase 604 includes one or more PRS cycles. Each PRS cycle includes group-based PRSs broadcast by one or more positioning groups. For example, within a PRS cycle, the wireless communication devices within each positioning group can broadcast their PRSs (and corresponding PRS measurement messages) within respective CoTs reserved by respective initiator devices. In some examples, the periodicity of the group phases 602a and 602b is less than the periodicity of the PRS cycles. For example, the PRS cycles can be 100 ms, and the periodicity of the group phases 602a and 602b can be 1000 ms. Thus, ten PRS cycles can occur between the group phases 602a and 602b.

[0095] Each group phase 602a and 602b can be further time-divided into a first initiator sub-phase 606, a responder sub-phase 608, and a second initiator sub-phase 610. Within the first initiator sub-phase 606, an anchor device can transmit an initiator group formation message to initiate a positioning group. Within the responder sub-phase 608, responder devices (e.g., non-anchor devices and anchor devices immediately adjacent to another anchor device that broadcasted an initiator group formation message in the initiator sub-phase 606) can broadcast a responder group formation message. Within the second initiator sub-phase 610, an initiator device can broadcast or groupcast a group association message that identifies members of its respective positioning group and a respective PRS broadcast order of the members in its respective positioning group.

[0096] In FIG. 6 In the illustrated example, an anchor device can broadcast (or groupcast) its initiator group formation message at time Unif(X+0, X+T1), where T1 is a time budget for the anchor device to broadcast its group formation message. In some examples, T1 = 100 ms. Here, X refers to the periodicity of the group phases 602a and 602b (e.g., X = 0 ms, 1000 ms, 2000 ms, 3000 ms,...). In some examples, each subsequent group phase (e.g., group phase 602b) can start after a time gap (X+T_g) from the end of the PRS phase 604 to minimize interference on the sidelink channel. Similarly, a responder device can broadcast its responder group formation message at time Unif(X+T1, X+T2), where T2 is a time budget for the responder device to broadcast its group formation message. In some examples, T2 > 100 ms. Then, each initiator device can broadcast its group association message at time Unif(X+T2, X+T3), where T3 is a time budget for the initiator device to broadcast its group association message. In some examples, T3 < 100 ms.

[0097] FIG. 7This is a diagram illustrating an example of a group formation broadcast message 700 that can be transmitted by a group initiator according to some aspects. The payload of the group formation broadcast message 700 includes several basic fields 702 carrying device information. The group formation broadcast message may further include a header (not shown), which may include, for example, the UE ID (e.g., MAC ID) of the transmitting device (e.g., the initiating device). The basic fields 702 may include, for example, an initiator field 704 carrying initiator information, an anchor field 706 carrying anchor information, a power field 708 carrying power information, and a group ID field 710 carrying the group ID of the transmitting device. The initiator information 704 indicates whether the transmitting device is the initiator device of the locating group. For example, the initiator information 704 may include a single bit I = {0,1}, where I = 1 indicates that the transmitting device is the initiator device, and I = 0 indicates that the transmitting device is the responder device. The anchor information 706 indicates whether the transmitting device is an anchor device or a non-anchor device. For example, anchor information 706 may 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.

[0098] 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. For a device with P = 1, the PRS cycle periodicity can be smaller than the normal PRS cycle periodicity to accommodate the transmitting device's DRX mode. Therefore, a transmitting device with P = 1 may not transmit the PRS in each PRS cycle during the PRS phase. Group ID 710 identifies the transmitting device within a location group. In some examples, the group ID can be a random number within the group. For example, such as... FIG. 7 As shown, the group ID can be a single bit ID selected from mod(N) = {0,1,…,N}. In other examples, the group ID can be the UE ID of the transmitting device (e.g., MAC ID).

[0099] FIG. 8 This is a diagram illustrating an example of a group-formed broadcast message 800 that can be transmitted by a group responder based on certain aspects. FIG. 8 In the example shown, the group formation broadcast message 800 payload includes a basic field 802 and a responder field 804. The group formation message 800 may further include a header (not shown), which includes, for example, the UEID (e.g., MAC ID) of the responder device making the transmission. The basic field 802 includes, for example,... FIG. 7The same fields shown above, and carrying device information of the transmitting device (e.g., the responding device of the group formation message 800). For example, basic field 802 includes an initiator field 806 carrying initiator information, an anchor field 808 carrying anchor information, a power field 810 carrying power information, and a group ID field 812 carrying the group ID of the transmitting device, as shown above. FIG. 7 The subject of discussion.

[0100] The responder field 804 may include an initiator ID field 814 carrying the initiator ID of the initiating device of the positioning group and a responder ID field 816 carrying a list of responder IDs. Each responder ID included in the responder ID field 816 is associated with a responder device that previously transmitted a responder group formation message 800 in the responder sub-phase, and the responder ID includes the initiator ID of the positioning group initiator device and the responder IDs of other responder devices that previously transmitted other responder group formation messages 800. In some examples, the initiator ID and responder ID may be the UE ID of each of the initiator and responder devices. In other examples, the initiator ID and responder ID may each be based on the respective group ID of the initiator and responder device. For example, the initiator ID may include a concatenation of the initiator group ID and the initiator UE ID. Alternatively, the responder ID may each include a concatenation of the corresponding responder group ID and the corresponding responder UE ID. As another example, the initiator ID and responder ID may each include the initiator group ID and the responder group ID, respectively.

[0101] FIG. 9 This is a diagram illustrating an example of a group-related broadcast message 900 that can be transmitted by the group initiator, based on certain aspects. FIG. 9 In the example shown, the group-associated broadcast message 900 payload includes a basic field 902 and a responder ID field 904. The group-associated broadcast message 900 may further include a header (not shown), which may include, for example, the UE ID of the initiating device (e.g., MAC ID). The basic field 902 includes, for example,... FIG. 7 The same fields shown above, and carrying device information of the transmitting device (e.g., the initiating device of the group association message 900). For example, basic field 902 includes an initiator field 906 carrying initiator information, an anchor field 908 carrying anchor information, a power field 910 carrying power information, and a group ID field 912 carrying the group ID of the transmitting device, as shown above. FIG. 7 The subject of discussion.

[0102] The responder ID field 904 includes a list of responder IDs 914 that identify members of the positioning group (e.g., responder devices) and an order of the responder devices in the positioning group. In some examples, the responder IDs 914 can be a UE ID or a respective group ID for each responder device. In other examples, the responder IDs 914 can each include a concatenation of a respective responder group ID and a respective responder UE ID for each responder device in the positioning group.

[0103] The order of the responder IDs 914 included in the responder ID field 904 corresponds to an order of the responder devices in the positioning group (e.g., an order in which the responder devices can transmit their respective PRSs). In some examples, the responder IDs 914 are listed in descending order, with a top (first) responder ID identifying a first responder device to transmit a PRS after the initiator device, a second responder ID identifying a second responder device to transmit a PRS after the first responder device, and so on.

[0104] In some examples, the order of the responder IDs 914 can be determined based on device information included in a basic field of the responder group formation message transmitted by each responder device. For example, referring now to FIG. 8 , the initiator field 806 can include most significant bits (MSBs), and the group ID field 812 can include least significant bits (LSBs). In this example, referring again to FIG. 9 , the order of the responder IDs 914 in the responder ID field 904 can result in the anchor devices being listed before the non-anchor devices, and the power-limited devices (e.g., which can generally be non-anchor devices) being listed after the non-power-limited devices. By placing the power-limited responder devices toward the bottom of the responder ID list, reduced latency between PRSs can be achieved even when the power-limited devices can not be awake during a particular PRS cycle.

[0105] FIG. 10 is a diagram illustrating an example of a positioning group formation by a plurality of wireless communication devices (WCD1 1002, WCD2 1004, WCD3 1006, WCD4 1008, and WCD5 1010) communicating over a sidelink channel, in accordance with some aspects. Each wireless communication device 1002, 1004, 1006, 1008, and 1010 can correspond to a sidelink device (e.g., a V2X device), such as an RSU, a V-UE, a P-UE, or other sidelink device. In FIG. 10 the illustrated example, WCD1 1002, WCD2 1004, and WCD4 1008 are anchor devices, and WCD3 1006 and WCD5 1010 are non-anchor devices.

[0106] During the first initiator 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 groupcast) an initiator group formation broadcast message (IGFM) on the sidelink channel. For example, at a first time (ti), WCD1 1002 can broadcast (or groupcast) a first initiator group formation message on the sidelink channel to form a positioning group 1018a that includes WCD1 1002. The first initiator 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 initiator group formation message.

[0107] For example, WCD4 1008 can receive the first initiator group formation broadcast message broadcast or groupcast from WCD1 1002 and measure the received power (e.g., RSRP) of the first initiator group formation message at WCD4 1008 to determine whether to join the WCD1 positioning group 1018a. In some examples, WCD4 1008 can compare the received power of the first initiator group formation message to a threshold (e.g., a threshold power) to determine whether to join the WCD1 positioning group 1018a. In an example, if the received power of the first initiator group formation message is less than the threshold, indicating that WCD1 1002 is located far away from WCD4 1008, then WCD4 1008 can decide not to join the WCD1 positioning group 1018a. However, if the received power of the first initiator group message is greater than or equal to the threshold, indicating that WCD1 1002 is proximate to WCD4 1008, as shown in the example of FIG. 10B, then WCD4 1008 can decide to join the WCD1 positioning group 1018a. Thus, at a second time (t2), WCD4 1008 can not transmit an initiator group formation message. FIG. 10

[0108] As another example, WCD2 1004 can also receive the first initiator group formation broadcast message broadcast (or groupcast) from WCD1 1002 and measure the received power of the first initiator group formation message at WCD2 1004. If the received power as measured at WCD2 1004 is greater than or equal to a threshold (e.g., which can be the same as or different from the threshold used by WCD4 1008), then WCD2 1004 can decide to join the WCD1 positioning group 1018a. However, as shown in the example of FIG. 10B, if the received power as measured at WCD2 1004 is less than the threshold, indicating that WCD1 1002 is located far away from WCD2 1004, then WCD2 1004 can decide not to join the WCD1 positioning group 1018a. Thus, at a second time (t2), WCD2 1004 can not transmit an initiator group formation message. FIG. 10 ​As shown by the example, WCD2 1004 can decide not to join the WCD1 positioning group 1018a if the received power of the first initiator group message is less than the threshold. Thus, at a third time (t3), WCD2 1004 can broadcast a second initiator group formation message over the sidelink channel to form a second positioning group 1018b that includes WCD2 1004.

[0109] During the responder sub-phase 1014 of the group phase, responder devices can broadcast respective responder group formation messages (RGFM) to join one of the positioning groups 1018a and 1018b. Here, the responder devices include the anchor device WCD4 1008 and the non-anchor devices WCD3 1006 and WCD5 1010. Each responder device WCD3 1006, WCD4 1008, and WCD5 1010 can receive each of the first initiator group formation message broadcast by WCD1 1002 and the second initiator group formation message broadcast by WCD2 1004 and determine whether to join the WCD1 positioning group 1018a or the WCD2 positioning group 1018b based on the received initiator group formation messages.

[0110] For example, WCD3 1006 can receive the first initiator group formation broadcast message broadcast by WCD1 1002 and the second initiator 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 initiator group formation broadcast messages and compare the received power of each of the first and second initiator group formation broadcast messages to select one of the positioning groups 1018a or 1018b based on the higher received power (as measured at WCD3 1006) of the first or second initiator group formation broadcast message. In FIG. 10 In the example shown, the received power of the first initiator group formation broadcast message broadcast (or groupcast) by WCD1 1002 is higher than the received power of the second initiator group formation broadcast message broadcast (or groupcast) by WCD2 1004 as measured by WCD3 1006. As such, at a fourth time (t4), WCD3 1006 can broadcast (or groupcast) a first responder group formation message to join the WCD1 positioning group 1018a. The first responder group formation broadcast message can include the initiator ID of the initiator device WCD1 1002 and the device information of WCD3 1006 (e.g., the responder ID of WCD3 1006), as shown in the basic fields 802 in FIG. 8. FIG. 8

[0111] ​The anchor responder device WCD4 1008 selects not to transmit an initiator group formation broadcast message during the initiator sub-phase 1012 based on a high RSRP (e.g., greater than or equal to a threshold) of the first initiator group formation message broadcast by WCD1 1002 at a first time (ti) as measured by WCD4 1008. Thus, during the responder sub-phase 1014, at a fifth time (t5), WCD4 1008 can broadcast (or groupcast) a second responder group formation broadcast message to join the WCD1 positioning group 1018a. The second responder group formation broadcast message can include an initiator ID of the initiator device WCD1 1002, a responder ID of WCD3 1006 that previously broadcasted (or groupcasted) a responder group formation broadcast message to join the WCD1 positioning group 1018, and device information in WCD4 1008 (e.g., a responder ID of WCD4 1008, a device ID of WCD4 1008, and a device type of WCD4 1008), as shown in the basic fields 802. FIG. 8

[0112] The non-anchor responder device WCD5 1010 can also receive the first initiator group formation broadcast message transmitted by WCD1 1002 and the second initiator group formation broadcast message transmitted by WCD2 1004. WCD5 1010 can further measure the received power (e.g., RSRP) of each of the first and second initiator group formation broadcast messages, and compare the received power of each of the first and second initiator group formation broadcast messages to select one of the positioning groups 1018a or 1018b based on the higher received power (as measured at WCD5 1010) in the first or second initiator group formation message.

[0113] In addition, WCD5 1010 can also receive each of the responder group formation broadcast messages previously broadcasted by WCD3 1006 and WCD4 1008 in the responder sub-phase 1014, and determine the positioning groups 1018a and 1018b selected by each of the responder devices WCD3 1006 and WCD4 1008. WCD5 1010 can further determine the number of responder devices that have joined each of the positioning groups 1018a and 1018b based on the received responder group formation broadcast messages. In addition, WCD5 1010 can determine whether any of the positioning groups 1018a and 1018b has reached a maximum number of members. For example, the maximum number of positioning group members can be preconfigured for all positioning groups, or the maximum number of positioning group members can be included in the initiator group formation messages broadcasted by the initiator devices. For example, if the positioning group 1018a has reached the maximum number of members, WCD5 1010 can select the other positioning group 1018b. In examples where more than two positioning groups are available, WCD5 1010 can select the positioning group with the highest initiator group formation message RSRP that has not reached the maximum number of members.​

[0114] In FIG. 10 In the example shown, at a sixth time (t6), WCD5 1010 can transmit a third responder group formation broadcast message to join WCD2 positioning group 1018b based on the higher received power of the initiator group formation message broadcast by WCD2 1004 or the maximum number of members reached by positioning group 1018a. The third responder group formation broadcast message can include the initiator ID of the initiator device WCD2 1004 and the device information of WCD5 1010 (e.g., the responder ID of WCD5 1010), as shown in the basic fields 802 in FIG. 8

[0115] During the second initiator sub-phase 1016, the initiator device of each of the positioning groups 1018a and 1018b (e.g., WCD1 1002 and WCD2 1004) can transmit a respective group association broadcast message that identifies the members of each positioning group and specifies a respective order of the members in that positioning group. For example, at a seventh time (t7), WCD1 1002 can transmit a first group association broadcast message that includes the initiator ID of WCD1 1002 and the responder IDs of WCD3 1006 and WCD4 1008 listed in an order for transmitting respective PRSs. Further, at an eighth time (t8), WCD2 1004 can transmit a second group association broadcast message that includes the initiator ID of WCD2 1004 and the responder ID of WCD5 1010.

[0116] FIG. 11 is a diagram illustrating an example of a group-based PRS broadcast according to some aspects. FIG. 11 The group-based PRS broadcast example shown in FIG. 11 As shown in the example of FIG. 11, the initiator device of a positioning group can reserve a sidelink channel for CoT 1102 sufficient for each member of the positioning group to transmit a PRS. In some examples, the initiator device can implement a class 4 LBT to reserve CoT 1102 for all of the positioning group members and transmit a first PRS (e.g., initiator PRS 1104) at time T_LBT. Thereafter, the responder devices in the positioning group can implement a class 2 LBT to broadcast their PRSs 1106, 1108, 1110, and 1112. Each PRS 1104-1112 can include a respective PRS sequence. For example, each PRS sequence can be a wideband random sequence broadcast over an unlicensed band. In some examples, each PRS can further include a sequence identifier (ID) that identifies the PRS sequence. As discussed, each broadcast described herein can instead be a groupcast.

[0117] ​Each responder device can determine its corresponding transmission timing for its PRS within CoT 1102 based on the group association message indicating the order of responder devices within the group. For example, each PRS 1104-1112 can have the same (e.g., set) duration denoted as t_{PRS}. Additionally, each responder device can provide a corresponding gap 1114 (denoted as t_{gap}) between the end of a previously transmitted PRS and the responder device's PRS. In some examples, the gap 1114 can be 25 μs. Upon determining that the first responder device (R1) is listed first in the group association message according to the responder device order, the first responder device (R1) can transmit a second PRS (R1 PRS) 1106 at time T_{LBT}+t_{PRS}+t_{gap}. Similarly, the second responder device (R2) can transmit the third PRS (R2PRS) at time T_{LBT}+2t_{PRS}+2t_{gap}. Furthermore, the third responder device (R3) can transmit the fourth PRS (R3 PRS) at time T_{LBT}+3t_{PRS}+3t_{gap} 1108. Generally, the PRS broadcast time of the k-th wireless communication device can be determined as: T_{LBT}+(k-1)t_{PRS}+(k-1)t_{gap}. By providing a fixed gap 1114 between the PRS and the known PRS transmission order, the waiting time between PRSs can be reduced, thereby improving the efficiency and accuracy of sidelink positioning.

[0118] Other responding devices (e.g., responding device R4) may transmit their respective PRS (e.g., R4PRS 1112) at the corresponding transmission time determined similarly to the order listed in the group association message. In some examples, power is limited (e.g., FIG. 8 The responder device (RD) with P=1 in the device information shown can be placed at the end of the responder list (e.g., at the bottom of the order). Such power-constrained responder devices (e.g., responder device R4) can have a lower duty cycle than non-power-constrained responder devices (e.g., responder devices with P=0), and thus do not need to transmit PRS every PRS cycle, as indicated by the shading of R4 PRS 1112. For example, a power-constrained responder device can transmit a PRS (and the corresponding PRS measurement message) every 500ms or 1000ms, while a non-power-constrained responder device can transmit a PRS every 100ms within a PRS phase. By placing the power-constrained responder device at the end of the list, the latency between coherent PRS 1104-1112 can be reduced during each PRS cycle.

[0119] FIG. 12An example of a device arrangement belonging to two PRS broadcast positioning groups in a scenario suitable for opportunistic CoT sharing is illustrated. Here, two positioning groups 1202a and 1202b are shown, but opportunistic CoT sharing can be established between more than two positioning groups in a similar manner. Positioning group 1202a includes an anchor initiator device (labeled I_A) 1204, two anchor responder devices (labeled R1_A and R2_A) 1206 and 1208, and two non-anchor responder devices (labeled R3_A and R4_A) 1210 and 1212. Positioning group 1202b includes an anchor initiator device (labeled I_B) 1214, two anchor responder devices (labeled R1_B and R2_B) 1216 and 1218, and a non-anchor responder device (labeled R3_B) 1220. As discussed, each broadcast described herein can instead be a groupcast.

[0120] As previously discussed, the two positioning groups 1202a and 1202b can be formed using messages such as an initiator group formation message (IGFM), a responder group formation message (RGFM), and a group association message (GAM). Generally, once the two positioning groups 1202a and 1202b are formed, the initiator device of each positioning group can independently implement a class 4 LBT to reserve a CoT for all of the positioning reference signals (PRS) of its group members. Thus, initiator device 1204 (I_A) can independently implement a class 4 LBT to reserve a CoT for responder devices 1206-1212 (R1_A through R5_A). Initiator device 1214 (I_B) can independently implement a class 4 LBT to reserve a different CoT for responder devices 1216-1220 (R1_B through R3_B).

[0121] Intra-group PRS signaling for RTT for positioning generally works well. PRS signal latency is well managed within each positioning group. Once the initiator device establishes a CoT using a class 4 LBT, each PRS signal can be broadcast in turn from different members of the positioning group (i.e., the initiator device, followed by each responder device) in a well-controlled and predictable manner. To broadcast its PRS signal, each responder device of the positioning group can only perform a class 2 LBT involving a simple clear channel assessment (CCA) without having to perform a contention channel “backoff” as in the class 4 LBT case. Thus, within the positioning group, all of the group members can broadcast their PRS signals in turn, all within a relatively compact and well-controlled timeframe - i.e., within the CoT. For example, responder device 1206 (R1_A) and responder device 1210 (R3_A) will broadcast their PRS signals within the same CoT. Thus, an RTT measurement between these two devices will involve a relatively low PRS latency.

[0122] In contrast, inter-group PRS signaling for establishing RTT across members of different positioning groups can suffer from significantly longer and less predictable PRS latency, which can result in significant degradation of RTT measurements. For example, responder device 1212 (R4_A) from positioning group 1202a and responder device 1216 (R1_B) from positioning group 1202b will generally not broadcast their PRS signals within the same CoT. Responder device 1212 (R4_A) will broadcast its PRS signal within a CoT established by initiator device 1204 (I_A). Responder device 1216 (R1_B) will broadcast its PRS signal within a different CoT established by initiator device 1214 (I_B). These two CoTs will be independently established, each with its own backoff. Thus, there can be significant latency between PRS signal broadcast from responder device 1212 (R4_a) from positioning group 1202a and PRS signal broadcast from responder device 1216 (R1_B) from positioning group 1202b. Such PRS signal latency can negatively impact the accuracy of RTT measurements performed for ranging between responder device 1212 (R4_A) and responder device 1216 (R1_B).

[0123] However, in certain scenarios, inter-group PRS signaling can be useful and appropriate. For example, if the accuracy of a particular multi-lateration operation can be significantly improved by including RTT measurements with anchors at or near a particular geographic location, and the only PRS-capable devices available near that geographic location are devices belonging to different positioning groups, then inter-group PRS signaling can be warranted. As discussed below, requests for inter-group PRS can be triggered in a number of different ways.

[0124] One category of such requests can be 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 responder device 1220 (R3_B) from positioning group 1202b receives PRS from devices in positioning group 1202a more than X times (e.g., X = 5), the responder device 1220 (R3_B) can request inter-group PRS signaling from positioning group 1202a. Another type of sensor-based trigger can be based on the frequency of receiving PRS signals from another positioning group. For example, if the responder device 1220 (R3_B) from positioning group 1202b receives PRS from devices in positioning group 1202a, and the associated reference signal received power (RSRP) measurements exceed some threshold (e.g., in an aggregated manner or in some other manner), the responder device 1220 (R3_B) can request inter-group PRS signaling from positioning group 1202a. Another category in inter-group PRS signal requests can be 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 can maintain positioning groups 1202a and 1202b. In such a scenario, the core network can determine and indicate a need for inter-group PRS signaling between positioning groups 1202a and 1202b.

[0125] The initiator device of a positioning group can receive a request for inter-group PRS signaling (from one of its responder devices or from the CN) and respond by attempting to establish opportunistic CoT sharing between the positioning groups. The initiator device can do so through coordination with the initiator device of the other positioning group. Such initiator-to-initiator coordination can occur over a separate channel, such as a dedicated channel over the ITS band. For example, the initiator device 1216 (I_B) of positioning group 1202b, upon receiving the inter-group PRS signaling request from responder device 1220 (R3_B), can coordinate with the initiator device 1204 (I_A) of positioning group 1202a. Alternatively, the initiator device can attempt to establish opportunistic CoT sharing independently, without coordination with other initiator devices. For example, the initiator device 1216 (I_B) of positioning group 1202b, upon receiving the inter-group PRS signaling request from responder device 1220 (R3_B), can attempt to share the CoT established for positioning group 1202a without coordination with the initiator device 1204 (I_A).

[0126] FIG. 13This is a timing diagram illustrating an example of the opportunity for CoT sharing between two PRS broadcast positioning groups. CoT sharing between more than two groups can be performed in a similar manner. However, for ease of explanation, only two groups are shown. As discussed, opportunistic CoT sharing can occur with or without coordination between the initiators of the respective positioning groups. As discussed, each broadcast described herein can alternatively be a multicast.

[0127] Reference 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 PRS broadcast sequence comprising data from initiating device 1204 and four responding devices 1206, 1208, 1210, and 1212 (from positioning group 1202a, as shown). FIG. 12 The broadcast includes an initiator PRS 1314 and four responders PRS 1316, 1318, 1320, and 1322. The initiator device 1204 can establish CoT 1306 by executing class 4LBT, which can set the start time of CoT 1306 based on a backoff time (“backoff A”) 1324. A second PRS broadcast sequence 1304 occurs within CoT 1326. The second PRS broadcast sequence 1304 includes PRS broadcast sequences, which include broadcasts from initiator device 1214 and three responders 1216, 1218, and 1220 (from positioning group 1202b, as shown). FIG. 12 The broadcast includes an initiator PRS 1334 and four responders PRS 1336, 1338, and 1340. The initiator device 1214 can establish CoT 1326 by executing class 4LBT, which can set the start time of CoT 1326 based on the backoff time (“backoff B”) 1342.

[0128] If initiating devices 1202 and 1204 coordinate to establish CoT sharing, they can each perform class 4LBT using a backoff counter initialized to a random number selected from an interval proportional to the sum of (1) the number of devices in their respective positioning groups and (2) the number of devices in another positioning group. Here, the sum of the number of devices from these two groups is 5 + 4 = 9. Therefore, initiating devices 1202 and 1204 each use a random number generator characterized by a uniform probability distribution function above the interval [0, 9] to generate random numbers to determine their respective backoff times. FIG. 13 As shown, initiating device 1202 therefore generates a backoff time of 1324. Initiating device 1204 therefore generates a backoff time of 1342.

[0129] If the initiator devices 1202 and 1204 do not coordinate to establish CoT sharing, they can each perform a Class 4 LBT using a backoff counter that is initialized to a random number selected from an interval that is proportional to the number of devices in its own positioning group. Thus, since there are 5 devices in the positioning group 1202a, the initiator 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 initiator 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].

[0130] Regardless of whether the initiator devices 1202 and 1204 coordinate to establish CoT sharing, the initiator device 1204 can attempt to "fit" the PRS associated with the positioning group 1202b into the CoT 1306, which is scheduled for the PRS associated with the positioning group 1202a. Because all group messages, including all group formation messages (IGFM), responder group formation messages (RGFM), and group association messages (GAM), are listened to by all devices, the initiator device 1204 is aware of the membership, order, etc. of the positioning group 1202a. Thus, the positioning group 1202b is able to determine the total PRS sequence duration 1344 of the PRS of the positioning group 1202a. The duration of the CoT 1306 is also typically known. The initiator device 1204 can thereby determine whether there is sufficient space in the CoT 1306 to fit the PRS of the positioning group 1202b. For example, if the remaining time in the CoT 1306 is greater than the duration 1346 of the PRS of the positioning group 1206b, the initiator device 1204 can proceed to attempt to broadcast the PRS of the positioning group 1202b in the CoT 1306.

[0131] As previously noted, while positioning reference signals (PRS) are used as an example to illustrate various aspects, different types of reference signals can alternatively be used, such as sounding reference signals (SRS) or other types of signals.

[0132] FIG. 14 Successful attempts to opportunistically share CoTs in accordance with embodiments are illustrated. As in the previous example, the initiator devices 1202 and 1204 are not coordinated to establish CoT sharing. Thus, the initiator device 1202 generates a backoff time 1324 using a random number generator characterized by a uniform probability distribution function over the interval [0, 5]. The initiator device 1204 generates a backoff time 1326 using a random number generator characterized by a uniform probability distribution function over the interval [0, 4]. FIG. 13In the context of the discussion, the initiator device 1202 and the initiator device 1204 can each plan to perform a Class 4 LBT and schedule a respective CoT. In doing so, each of the initiator device 1202 and the initiator device 1204 can set a backoff using a randomly selected number. The first initiator device to complete counting down its backoff time and successfully complete a clear channel assessment (CCA) proceeds to establish a CoT for its positioning group broadcast PRS signal. In this case, at time 1402, the initiator device 1202 first completes counting down its backoff time 1324 and successfully completes a CCA. As such, the initiator device 1202 establishes a CoT 1306 and broadcasts its PRS 1314, and its responder devices broadcast PRS 1316, 1318, 1320, and 1322, respectively. As discussed, each broadcast described herein can instead be a groupcast.

[0133] In response, the initiator device 1304 evaluates two conditions. First, the initiator device 1304 determines whether there is sufficient space after the PRS 1314, 1316, 1318, 1320, and 1322 for the CoT 1306 to accommodate the PRS of the positioning group 1202b, i.e., PRS 1334, 1336, 1338, and 1340. In this example, there is sufficient space. In other words, the duration LB 1346 is less than the CoT 1306 minus the duration LA 1344 (LB < CoT - LB). Second, the initiator device 1304 performs a Class 2 LBT at the end of the PRS of the positioning group 1202a, at time 1404. The Class 2 LBT includes a clear channel assessment (CCA). Here, the CCA is successfully completed (CCA_B = 1). After satisfying both conditions, the initiator device 1304 proceeds to broadcast its PRS 1334. The responders of the initiator device 1304 also broadcast their respective PRS 1336, 1338, and 1340. In this way, the initiator device 1304 can avoid the planned Class 4 LBT to establish its own CoT. Instead, the initiator device 1304 opportunistically successfully shares the CoT 1306 established by the initiator 1302.

[0134] FIG. 15 An attempt to opportunistically share a CoT as a result of a transmission time deficit is illustrated in accordance with an embodiment. Similar to the example of FIG. 13, the initiator device 1302 establishes a CoT 1306 for its positioning group 1202b. The initiator device 1302 then broadcasts its PRS 1314, 1316, 1318, 1320, and 1322. The initiator device 1304 is a responder of the positioning group 1202b and plans to perform a Class 4 LBT and schedule a CoT for its own positioning group 1202c. In doing so, the initiator device 1304 sets a backoff using a randomly selected number. The initiator device 1304 completes counting down its backoff time and successfully completes a CCA. As such, the initiator device 1304 establishes a CoT 1308 and broadcasts its PRS 1334, 1336, 1338, and 1340. The initiator device 1304’s responders broadcast their respective PRS 1336, 1338, and 1340. In this way, the initiator device 1304 can avoid the planned Class 4 LBT to establish its own CoT. Instead, the initiator device 1304 opportunistically successfully shares the CoT 1306 established by the initiator 1302. FIG. 14In the scenario of FIG. 13, the initiator device 1304 first completes a countdown of its back-off time 1342 and successfully completes a CCA. As such, the initiator device 1304 establishes a CoT 1306 and broadcasts its PRS 1314, and its responder devices broadcast PRSs 1316, 1318, 1320, and 1322, respectively. In response, the initiator device 1304 evaluates the same two conditions previously discussed. Here, the initiator device 1304 determines that there is not enough room in the CoT 1306 to accommodate the PRSs of the positioning group 1202b after the PRSs 1314, 1316, 1318, 1320, and 1322. In other words, the duration LB 1346 is greater than the CoT 1306 minus the duration LA 1344 (LB > CoT - LB). Upon determining that opportunistic sharing of the CoT 1306 is not possible, the initiator device 1304 retrieves its previously generated back-off time 1342. As originally planned, at time 1502, the initiator device 1304 uses the back-off time 1342 to perform a class 4 LBT in order to establish its own CoT 1326. The initiator device 1304 then proceeds to broadcast its PRS 1334, and the responder devices of the initiator device 1304 also broadcast their respective PRSs 1336, 1338, and 1340 within the CoT 1326. As discussed, each broadcast described herein can instead be a groupcast.

[0135] FIG. 16 An attempt to opportunistic sharing of a CoT as a result of a failed clear channel assessment (CCA) is illustrated in accordance with an embodiment. Similar to the scenario of FIG. 12, FIG. 14 and 15In the scenario of FIG. 13B, the initiator device 1202 first completes counting down its back-off time 1324 and successfully completes the CCA. As such, the initiator device 1202 establishes the CoT 1306 and broadcasts its PRS 1314, and its responder devices broadcast PRSs 1316, 1318, 1320, and 1322, respectively. In response, the initiator device 1304 evaluates the same two conditions discussed previously. Here, the initiator device 1304 determines that after the PRSs 1314, 1316, 1318, 1320, and 1322, there is enough room in the CoT 1306 to accommodate the PRSs of the positioning group 1202b. In other words, the duration LB 1346 is less than the CoT 1306 minus the duration LA 1344 (LB < CoT - LB). Next, the initiator device 1304 performs a class 2 LBT including a CCA at the end of the PRSs of the positioning group 1202a, at time 1602. In this case, there is no interfering signal 1604 when the CCA is performed, and the CCA succeeds (CCA_B = 1). As a result, the opportunity to share the CoT 1306 is pursued. Again, after determining that opportunistic sharing of the CoT 1306 will occur, the initiator device 1304 retrieves its previously generated back-off time 1342. As originally planned, at time 1606, the initiator device 1304 uses the back-off time 1342 to perform a class 4 LBT in order to establish its own CoT 1326. Then, the initiator device 1304 continues to broadcast its PRS 1334, and the responder devices of the initiator device 1304 also broadcast their respective PRSs 1336, 1338, and 1340 within the CoT 1326. As discussed, each broadcast described herein can instead be a groupcast.

[0136] FIG. 17 FIG. 17 is a block diagram illustrating an example of a hardware implementation for a wireless communication device 1700 employing a processing system 1714. For example, the wireless communication device 1700 can correspond to a sidelink (e.g., V2X) device, such as an RSU, a V-UE, a P-UE, or other suitable sidelink device, as described above with reference to FIG. 10. FIGS. 1-5

[0137] ​The wireless communication device 1700 can be implemented with a processing system 1704 that includes one or more processors 1714. Examples of processors 1704 include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality 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, as utilized in a wireless communication device 1700, can be used to implement any one or more of the processes and procedures described below.

[0138] In this example, the processing system 1714 can be implemented with a bus architecture, as is represented generally by the bus 1702. The bus 1702 can include any number of interconnecting buses and bridges depending on the specific application of the processing system 1714 and the overall design constraints. The bus 1702 links together various circuits including one or more processors (represented by processor 1704), memory 1705, and computer-readable media (represented by computer-readable media 1706). The bus 1702 can also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be further described.

[0139] The bus interface 1708 provides an interface between the bus 1702 and the transceiver 1710. The transceiver 1710 provides a means for communicating with various other apparatus over a transmission medium (e.g., an air interface). The bus interface 1708 further provides an interface between the bus 1702 and a power source 1720 (e.g., a battery). Depending on the particular implementation, a user interface 1712 (e.g., a keypad, display, touch screen, speaker, microphone, control knobs, etc.) can also be provided. Of course, such a user interface 1712 is optional, and can be omitted in some examples.

[0140] The processor 1704 is responsible for managing the bus 1702 and general processing, including the execution of software stored on the computer-readable medium 1706. The software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software, when executed by the processor 1704, causes the processing system 1714 to perform the various functions described below for any particular apparatus. The computer-readable medium 1706 and the memory 1705 can also be used for storing data that is manipulated by the processor 1704 when executing software.

[0141] The computer-readable medium 1706 can be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, for example, magnetic storage devices (e.g., hard disk; floppy disk); optical disk devices (e.g., compact disk (CD), digital versatile disk (DVD)); smart cards; flash memory devices (e.g., card, stick, or key drive); random access memories (RAMs); read only memories (ROMs); programmable ROMs (PROMs); erasable PROMs (EPROMs); electrically erasable PROMs (EEPROMs); registers; removable disk; 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 in the processor system 1714, external to the processor system 1714, or distributed across multiple entities including the processor system 1714. The computer-readable medium 1706 can be embodied in a computer program product. By way of example, a computer program product can include a computer-readable medium in 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 functionality for the processor 1704, depending on the particular application and the overall design constraints imposed on the overall system.

[0142] In some aspects of the disclosure, the processor 1704 can include circuitry configured for various functions. For example, the processor 1704 can include communication and processing circuitry 1742 configured to communicate with other wireless communication devices (e.g., RSUs, V-UEs, P-UEs, etc.) over a sidelink channel. In some examples, the communication and processing circuitry 1742 can include one or more hardware components that provide the physical structure that performs processes related to wireless communication (e.g., signal reception and / or signal transmission) and signal processing (e.g., processing a received signal and / or processing a signal for transmission).

[0143] In some examples, the communication and processing circuitry 1742 can be configured to broadcast a group formation message over a sidelink channel via the transceiver 1710. The communication and processing circuitry 1742 can be further configured to receive one or more group formation messages broadcast by other wireless communication devices via the transceiver 1710. The communication and processing circuitry 1742 can be further configured to store the received group formation messages (GFMs) 1716 in the memory 1705 for further processing.

[0144] The communication and processing circuitry 1742 can be further configured to broadcast or receive a group association message (GAM) 1718 via the transceiver 1710, the GAM 1718 indicating an order 1722 of a plurality of wireless communication devices within a positioning group that includes the wireless communication device 1700. The communication and processing circuitry 1742 can be further configured to broadcast a positioning reference signal (PRS) within the positioning group and receive PRS broadcasts from other wireless communication devices within the positioning group. The communication and processing circuitry 1742 can be further configured to execute communication and processing instructions (software) 1752 stored in the computer-readable medium 1706 to implement one or more functions described herein.

[0145] The processor 1704 can further include group formation circuitry 1744 configured to generate group formation messages (e.g., initiator group formation messages or responder group formation messages) to be broadcast over a sidelink channel and to process group formation messages (e.g., initiator group formation messages and / or responder group formation messages) received from other wireless communication devices. In examples in which the wireless communication device 1700 is an anchor device, the group formation circuitry 1744 can be configured to determine whether an initiator group formation message has been received from another anchor initiator wireless communication device during an initiator sub-phase of a current group phase in which a positioning group can be formed.

[0146] If an initiator group formation message has been received, the group formation circuitry 1744 can measure the received power (e.g., RSRP) of the initiator group formation message and compare the received power to a threshold 1724, which can be stored in, for example, the memory 1705. If the received power of the initiator group formation message is greater than the threshold 1724, the initiator group formation message 1716 can be stored in the memory 1705 and used by the group formation circuitry 1744 to generate a responder group formation message during a responder sub-phase of a current group phase to join a positioning group initiated by the initiator group formation message. Here, the anchor device 1700 is functioning as a responder device. Otherwise, if the received power of the initiator group formation message is less than or equal to the threshold 1724, the group formation circuitry 1744 can discard the received initiator group formation message and generate a new initiator group formation message to form a new positioning group of the wireless communication device 1700. Here, the anchor device is functioning as an initiator device. If no other initiator group formation message is received within an initiator sub-phase, the anchor device 1700 can function as an initiator device and the group formation circuitry 1744 can generate an initiator group formation message to form a positioning group of the wireless communication device 1700.

[0147] In examples where the wireless communication device 1700 is an initiator device that broadcasts an initiator group formation message during a current initiator sub-phase to form a positioning group, the group formation circuitry 1744 can be further configured to receive one or more responder group formation messages 1716 from responder devices during a responder sub-phase of the current group phase. Each responder group formation message 1716 can include, for example, device information associated with the respective responder device, an initiator ID of the initiator device 1700, and respective responder IDs of other responder devices that previously broadcasted a responder group formation message to join the positioning group of the initiator device 1700. The received responder group formation messages 1716 can be stored, for example, in the memory 1705 for further processing. For example, the group formation circuitry 1744 can be further configured to utilize the received responder group formation messages 1716 to determine an order 1722 of the responder devices for transmitting respective PRSs during a PRS phase that is temporally subsequent to the current group phase. The order 1722 can be based on, for example, the device information associated with each responder device. In some examples, the order 1722 can include a list of responder devices in descending order, such that a first listed responder device should broadcast a PRS after the initiator device, a second listed responder device should broadcast a PRS after the first listed responder device, and so on. The group formation circuitry 1744 can be further configured to generate a group association message (GAM) for the positioning group. The GAM 1718 can include, for example, the initiator ID of the initiator device 1700 and the order 1722 of the responder devices. The GAM 1718 can be broadcasted during a second initiator sub-phase of the current group phase.

[0148] In examples where the wireless communication device 1700 is a non-anchor device, the non-anchor device 1700 can determine whether an initiator group formation message has been received from an initiator device during an initiator sub-phase of a current group phase. If the initiator group formation message has not been received, the group formation circuitry 1744 can function as an initiator device to generate an initiator group formation message and broadcast the initiator device group formation message during a responder sub-phase of the current group phase to form a positioning group for the non-anchor device 1700.

[0149] If one or more initiator group formation messages 1716 have been received, the non-anchor device 1700 can function as a responder device to select a positioning group to join based on the received initiator group formation messages 1716. For example, the received initiator group formation messages can be stored in the memory 1705 until a positioning group is selected for the non-anchor device. For example, the group formation circuitry 1744 can measure a received power (e.g., RSRP) of each initiator group formation message 1716 and select the positioning group associated with the initiator group formation message 1716 having the highest received power.

[0150] As another example, the group formation circuitry 1744 can determine a number of members in each positioning group associated with the received initiator group formation messages 1716. The number of members of a particular positioning group can be determined, for example, based on the responder group formation messages 1716 received for the particular positioning group during the responder sub-phase of the current group phase. For example, the group formation circuitry 1744 can be configured to count the number of responder group formation messages 1716 received for each positioning group. If the number of members of a positioning group has reached a maximum number of members, the group formation circuitry 1744 can not select the positioning group. Instead, the group formation circuitry 1744 can select another positioning group whose number of members has not reached the maximum number of members. Here, the maximum number of members of a positioning group can be predetermined and stored, for example, in the memory 1705 or included in the initiator group formation messages. In some examples, the group formation circuitry 1744 can further select a positioning group from the remaining positioning groups having a number of members less than the maximum number of members based on a received power of the corresponding initiator group formation messages 1716.

[0151] Upon selecting a positioning group to join, the group formation circuitry 1744 can then generate a responder group formation message to be broadcast during the responder sub-phase of the current group phase. The responder group formation message can include, for example, device information associated with the non-anchor device 1700, an initiator ID of the initiator device of the selected positioning group, and a corresponding responder ID of a responder device that previously broadcast a responder group formation message 1716 to join the positioning group before the responder group formation message is generated by the group formation circuitry 1744. In addition, the group formation circuitry 1744 can receive the GAM 1718 including the order 1722 of responder devices from the initiator device of the positioning group. The group formation circuitry 1744 can be further configured to execute group formation instructions (software) 1754 stored in the computer-readable medium 1706 to implement one or more functions described herein.

[0152] The processor 1704 can further include PRS generation circuitry 1746 configured to generate a PRS to be broadcast to a positioning group during a PRS phase. For example, the PRS can include a PRS sequence. The PRS sequence can be a wideband random sequence broadcast over an unlicensed band. In some examples, the PRS can include a sequence identifier (ID) identifying the PRS sequence. The PRS generation circuitry 1746 can further determine a transmission timing of the PRS based on an order 1722 of the wireless communication devices in the positioning group. In examples where the wireless communication device is an initiator device of the positioning group, the PRS generation circuitry 1746 can be configured to implement a Class 4 LBT to reserve a sidelink channel for a CoT and broadcast a first PRS to the positioning group within the CoT. In examples where the wireless communication device is a responder device, the PRS generation circuitry 1746 can be configured to broadcast a PRS to the positioning group within a CoT at a transmission time determined according to the order 1722 of the responder device. The PRS generation circuitry 1746 can be further configured to execute PRS generation instructions (software) 1756 stored in the computer-readable medium 1706 to implement one or more functions described herein.

[0153] FIG. 18 is a flow diagram 1800 illustrating an example method for group-based PRS broadcasting, in accordance with some aspects. As described below, some or all of the features illustrated can be omitted in some implementations, and some illustrated features can not be required for implementation of all embodiments. In some examples, the method can be performed by the wireless communication device 1700 as described above and illustrated in FIG. 17, by a processor or processing system, or by any suitable apparatus for performing the described functions. FIG. 17

[0154] At block 1802, a wireless communication device (e.g., a first wireless communication device) can transmit a first group formation broadcast message associated with a first positioning group, the first positioning group including a first plurality of wireless communication devices including the first wireless communication device. In some examples, the first wireless communication device can transmit the first group formation broadcast message within a group phase in a time domain. The group phase can include at least an initiator sub-phase (in which initiator devices can broadcast respective group formation broadcast messages) and a responder sub-phase (in which responder devices can broadcast respective group formation broadcast messages). The initiator devices can include at least anchor devices, each anchor device having a respective known location based on location accuracy. The responder devices include at least non-anchor devices, each non-anchor device having a respective unknown location based on location accuracy.

[0155] ​At block 1804, the first wireless communication device can receive a second group formation broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices including the second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel. The second plurality of wireless communication devices can be configured to communicate reference signals (e.g., PRSs) using transmission opportunities within the CoT.

[0156] At block 1806, the first wireless communication device can 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. For example, the PRS generation circuitry 1746 shown and described above in connection with FIG. 17 The PRS generation circuitry 1746, together with the communication and processing circuitry 1742 and the transceiver 1710, can provide a means for communicating reference signals, as described supra.

[0157] In one configuration, the wireless communication device 1700 includes means for group-based PRS broadcasting as described supra. In one aspect, the aforementioned means can be the processor 1704 shown in FIG. 17 configured as described supra to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means can be circuitry or any equipment configured to perform the functions recited by the aforementioned means. FIG. 17

[0158] Of course, in the above examples, the circuitry included in the processor 1704 is merely provided as an example, and other means for carrying out the described functions can be included within various aspects of the present disclosure, including but not limited to the processor 1704, the communication and processing circuitry 1742, the transceiver 1710, and / or any other suitable apparatus or means FIGS. 1-5 within the communication system 1700 or any other suitable apparatus or means described FIG. 18 herein, and utilizing, for example, the processes and / or algorithms described supra and / or described in connection with FIGS. 1-16.

[0159] Aspects of the wireless communication networks have been presented with reference to example implementations. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure can be extended to other telecommunication systems, network architectures and communication standards.

[0160] ​By way of example, various aspects can be implemented within other systems defined by 3 GPP, such as Long-Term Evolution (LTE), Evolved Packet System (EPS), the Universal Mobile Telecommunication System (UMTS), and / or the Global System for Mobile (GSM). Various aspects can also be implemented within systems defined by 3rd Generation Partnership Project 2 (3GPP2), such as CDMA2000 and / or Evolution-Data Optimized (EV-DO). For example, various aspects can be implemented within systems employing IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wide Band (UWB), Bluetooth, and / or other suitable systems. The actual telecommunication standard, network architecture, and / or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

[0161] Within the present disclosure, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any implementation or aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspects" does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term "coupled" is used herein to express a direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C can still be considered coupled to one another, even though they are not directly physically in contact with one another. For instance, a first object can be coupled to a second object even though the first object is never directly physically in contact with the second object. The terms "circuit" and "circuitry" are used broadly, and intended to include both hardware implementations of electrical devices, and software implementations of information and instructions that, when executed by a processor, cause the processor to implement the described functionality of the circuitry. The term "circuitry" is not limited to electrical circuits.

[0162] FIGS. 1-18 One or more of the components, steps, features and / or functions illustrated in the figures can be rearranged 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 can also be added without departing from the novel features disclosed herein. FIGS. 1-5 The apparatuses, devices and / or components illustrated in FIGS. 1, 10, and / or 17 can be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein can also be efficiently implemented in software and / or embedded in hardware.

[0163] It is to be understood that the specific order or hierarchy of steps in the methods disclosed are an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods can be re-arranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited in the description.

[0164] The previous description is provided to enable any person 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 generic principles defined herein can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. The phrase "at least one of' followed by a list of two or more items means that at least one of the items in the list is present, but does not exclude more than one of the items being present. As an example, "at least one of: a, b, and c" means that a is present, b is present, c is present, both a and b are present, both b and c are present, a and c are present, a, b, and c are present, or any combination of some or all of the items. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The embodiments described and pictured herein are presented by way of example only and are not intended to limit the concepts described herein to particular embodiments. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined in accordance with the following claims and their equivalents.

[0165] Implementation examples are described in the following numbered clauses:

[0166] Clause 1 : A method for device position estimation comprising, at a first wireless communication device: transmitting a first group formation broadcast message associated with a first positioning group, the 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, the second positioning group comprising a second plurality of wireless communication devices including the second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT comprising transmission opportunities configured to be used by the second plurality of wireless communication devices for communicating reference signals; and initiating 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.

[0167] Clause 2: The method of clause 1, wherein initiating transmission of the reference signals by the first plurality of wireless communication devices comprises: at the first wireless communication device, transmitting a first reference signal of an ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices using a first of additional transmission opportunities within the CoT associated with the second positioning group.

[0168] Clause 3: The method of any of clauses 1-2, further comprising: at the first wireless communication device, prior to transmitting the first reference signal, broadcasting a group association broadcast message specifying an order of transmission of the ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

[0169] Clause 4: The method of any of clauses 1-3, wherein initiating transmission of the reference signals by the first plurality of wireless communication devices is performed in response to a sensor-based trigger.

[0170] Clause 5: The method of clause 4, wherein the sensor-based trigger is based on a frequency of reference signals received from the second plurality of wireless communication devices.

[0171] Clause 6: The method of 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.

[0172] Clause 7: The method of any of clauses 1-3, wherein initiating transmission of the reference signals by the first plurality of wireless communication devices is performed in response to a network-based trigger.

[0173] Clause 8: The method of any of clauses 1-7, further comprising coordinating 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.

[0174] Clause 9: The method of clause 8, wherein a start time of the CoT is based on a back-off time selected from an interval based on (a) a count of a number of reference signals associated with the first plurality of wireless communication devices and (b) a count of a number of reference signals associated with the second plurality of wireless communication devices.

[0175] Clause 10: The method of any of clauses 1-9, further comprising establishing sharing of the CoT independently between the first plurality of wireless communication devices and the second plurality of wireless communication devices without coordinating with the second wireless communication device.

[0176] Clause 11: The method of clause 10, wherein the start time of the CoT is based on a back-off time selected from an interval based on a count of a number of reference signals associated with the second plurality of wireless communication devices.

[0177] Clause 12: The method of any of clauses 1-11, further comprising: determining a first duration of reference signal transmissions by the first plurality of wireless communication devices; determining a second duration of reference signal transmissions by the second plurality of wireless communication devices; and confirming, prior to initiating the reference signal transmissions by the first plurality of wireless communication devices using the additional transmission opportunities within the CoT associated with the second positioning group, that the first duration of reference signal transmissions is less than the CoT minus the second duration of reference signal transmissions.

[0178] Clause 13: The method of clause 12, further comprising: performing a successful clear channel assessment (CCA) prior to initiating the reference signal transmissions by the first plurality of wireless communication devices using the additional transmission opportunities within the CoT associated with the second positioning group.

[0179] Clause 14: The method of any of clauses 1-13, wherein the reference signals support round trip time (RTT) measurements between (a) at least one wireless communication device of the first plurality of wireless communication devices and (b) at least one wireless communication device of the second plurality of wireless communication devices.

[0180] Clause 15: The method of any of clauses 1-14, further comprising communicating with the second wireless communication device using a separate channel.

[0181] Clause 16: The method of clause 15, wherein the separate channel is within an intelligent transport systems (ITS) band.

[0182] Clause 17: The method of any of clauses 1-16, wherein the sidelink channel is within an unlicensed spectrum.

[0183] 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: transmit, using the wireless transceiver, a first group formation broadcast message associated with a first positioning group, the first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; receive, using the wireless transceiver, a second group formation broadcast message associated with a second positioning group, the 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 transmission opportunities configured to be used by the second plurality of wireless communication devices for communicating reference signals; and 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.

[0184] Clause 19: The first wireless communication device of Clause 18, wherein the processor is configured to initiate transmission of reference signals by the first plurality of wireless communication devices by: transmitting, at the first wireless communication device, a first reference signal of an ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices using a first of the additional transmission opportunities within the CoT associated with the second positioning group.

[0185] Clause 20: The first wireless communication device of Clause 19, wherein the processor is further configured to: broadcast a group association broadcast message prior to transmitting the first reference signal, the group association broadcast message specifying an order of transmission of the ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

[0186] Clause 21: The first wireless communication device of any of Clauses 18-20, wherein the processor is further configured to: initiate transmission of reference signals by the first plurality of wireless communication devices in response to a sensor-based trigger.

[0187] Clause 22: The first wireless communication device of Clause 21, wherein the sensor-based trigger is based on a frequency of reference signals received from the second plurality of wireless communication devices.

[0188] Clause 23: The first wireless communication device of 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.

[0189] Clause 24: The first wireless communication device of any of Clauses 18-20, wherein the processor is further configured to: initiate transmission of reference signals by the first plurality of wireless communication devices in response to a network-based trigger.

[0190] Clause 25: The first wireless communication device of any of clauses 18-24, wherein the processor is further configured to coordinate 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.

[0191] Clause 26: The first wireless communication device of clause 25, wherein a start time of the CoT is based on a back-off time selected from an interval based on (a) a count of a number of reference signals associated with the first plurality of wireless communication devices and (b) a count of a number of reference signals associated with the second plurality of wireless communication devices.

[0192] Clause 27: The first wireless communication device of any of clauses 18-24, wherein the processor is further configured to establish sharing of the CoT independently between the first plurality of wireless communication devices and the second plurality of wireless communication devices without coordination with the second wireless communication device.

[0193] Clause 28: The first wireless communication device of clause 27, wherein a start time of the CoT is based on a back-off time selected from an interval based on a count of a number of reference signals associated with the second plurality of wireless communication devices.

[0194] Clause 29: The first wireless communication device of any of clauses 18-28, wherein the processor is further configured to determine a first duration of reference signal transmissions by the first plurality of wireless communication devices, determine a second duration of reference signal transmissions by the second plurality of wireless communication devices, and confirm that the first duration of reference signal transmissions is less than the CoT minus the second duration of reference signal transmissions before initiating reference signal transmissions by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

[0195] Clause 30: The first wireless communication device of clause 29, wherein the processor is further configured to perform a successful clear channel assessment (CCA) before initiating reference signal transmissions by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

[0196] Clause 31: The first wireless communication device of any of clauses 18-30, wherein the reference signals support round trip time (RTT) measurements between (a) at least one wireless communication device of the first plurality of wireless communication devices and (b) at least one wireless communication device of the second plurality of wireless communication devices.

[0197] Clause 32: The first wireless communication device of any of clauses 18-31, wherein the processor is further configured to communicate with the second wireless communication device using a separate channel.

[0198] Clause 33: The first wireless communication device of Clause 32, wherein the individual channel is within an intelligent transportation system (ITS) frequency band.

[0199] Clause 34: The first wireless communication device of any of Clauses 18-33, wherein the sidelink channel is within an unlicensed spectrum.

[0200] 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, the 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, the 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 transmission opportunities configured to be used by the second plurality of wireless communication devices for communicating reference signals; and means for initiating 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.

[0201] Clause 36: A non-transitory computer-readable medium having stored therein instructions for one or more processing units to execute, comprising instructions to: transmit a first group formation broadcast message associated with a first positioning group, the first positioning group comprising a first plurality of wireless communication devices including the first wireless communication device; receive a second group formation broadcast message associated with a second positioning group, the 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 transmission opportunities configured to be used by the second plurality of wireless communication devices for communicating reference signals; and 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.

Claims

1. A method for device location estimation, comprising at a first wireless communication device: A first group of broadcast messages associated with a first location group is transmitted, the first location group including a first plurality of wireless communication devices containing the first wireless communication device; Receive a second group forming broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices containing a second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT including transmission opportunities configured for the second plurality of wireless communication devices to convey reference signals; as well as In response to receiving the second group formation broadcast message, a transmission of a reference signal is initiated by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

2. The method of claim 1, wherein initiating the transmission of the reference signal by the first plurality of wireless communication devices comprises: At the first wireless communication device, a first additional transmission opportunity is used from the additional transmission opportunities within the CoT associated with the second positioning group to transmit a first reference signal in an ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

3. The method of claim 2, further comprising: At the first wireless communication device, before transmitting the first reference signal, a group-associated broadcast message is broadcast, the group-associated broadcast message specifying the transmission order of an ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

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

5. The method of claim 4, wherein the sensor-based triggering is based on the frequency of a reference signal received from the second plurality of wireless communication devices.

6. The method of claim 4, wherein the sensor-based triggering 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.

7. The method of claim 1, wherein initiating the transmission of the reference signal by the first plurality of wireless communication devices is performed in response to a network-based trigger.

8. The method of claim 1, further comprising: Coordinate with the second wireless communication device to establish the sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices.

9. The method of claim 8, wherein the start time of 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.

10. The method of claim 1, further comprising: The CoT is shared independently between the first plurality of wireless communication devices and the second plurality of wireless communication devices, without coordination with the second wireless communication device.

11. The method of claim 10, wherein the start time of the CoT is based on a backoff time selected from an interval based on a count of the number of reference signals associated with the second plurality of wireless communication devices.

12. The method of claim 1, further comprising: Determine the first duration of reference signal transmission performed by the first plurality of wireless communication devices; Determine the second duration of reference signal transmission performed by the second plurality of wireless communication devices; as well as Before initiating the transmission of a reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group, it is confirmed that the first duration of the reference signal transmission is less than the CoT minus the second duration of the reference signal transmission.

13. The method of claim 12, further comprising: Before initiating the transmission of reference signals by the first plurality of wireless communication devices using the additional transmission opportunities within the CoT associated with the second location group, a successful unobstructed channel assessment (CCA) is performed.

14. The method of claim 1, wherein the reference signal supports round-trip time (RTT) measurement between at least one of the first plurality of wireless communication devices and at least one of the second plurality of wireless communication devices.

15. The method of claim 1, further comprising: Communicate with the second wireless communication device using a separate channel.

16. The method of claim 15, wherein the individual channel is located within the Intelligent Transmission System (ITS) band.

17. The method of claim 1, wherein the sidelink channel is located in unlicensed spectrum.

18. A first wireless communication device in a wireless communication network, comprising: Wireless transceiver; Memory; as well as A processor communicatively coupled to the wireless transceiver and the memory, wherein the processor is configured to: Using the wireless transceiver, a first group broadcast message associated with a first location group is transmitted, the first location group including a first plurality of wireless communication devices containing the first wireless communication device; Using the wireless transceiver, a second group forming broadcast message is received associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices containing a second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT including transmission opportunities configured for the second plurality of wireless communication devices to transmit reference signals; as well as In response to receiving the second group formation broadcast message, the transmission of reference signals is initiated by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

19. The first wireless communication device of claim 18, wherein the processor is configured to initiate the transmission of the reference signal by the first plurality of wireless communication devices by: At the first wireless communication device, a first additional transmission opportunity is used from the additional transmission opportunities within the CoT associated with the second positioning group to transmit a first reference signal in an ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

20. The first wireless communication device of claim 19, wherein the processor is further configured to: Before transmitting the first reference signal, a group-associated broadcast message is broadcast, which specifies the transmission order of the ordered sequence of reference signals to be transmitted from the first plurality of wireless communication devices.

21. The first wireless communication device of claim 18, wherein the processor is further configured to: The transmission of the reference signal by the first plurality of wireless communication devices is initiated in response to a sensor-based trigger.

22. The first wireless communication device of claim 21, wherein the sensor-based triggering is based on the frequency of a reference signal received from the second plurality of wireless communication devices.

23. The first wireless communication device of claim 21, wherein the sensor-based triggering 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.

24. The first wireless communication device of claim 18, wherein the processor is further configured to: The transmission of the reference signal by the first plurality of wireless communication devices is initiated in response to a network-based trigger.

25. The first wireless communication device of claim 18, wherein the processor is further configured to: Coordinate with the second wireless communication device to establish the sharing of the CoT between the first plurality of wireless communication devices and the second plurality of wireless communication devices.

26. The first wireless communication device of claim 25, wherein the start time of 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.

27. The first wireless communication device of claim 18, wherein the processor is further configured to: The CoT is shared independently between the first plurality of wireless communication devices and the second plurality of wireless communication devices, without coordination with the second wireless communication device.

28. The first wireless communication device of claim 27, wherein the start time of the CoT is based on a backoff time selected from an interval based on a count of the number of reference signals associated with the second plurality of wireless communication devices.

29. The first wireless communication device of claim 18, wherein the processor is further configured to: Determine the first duration of reference signal transmission performed by the first plurality of wireless communication devices; Determine the second duration of reference signal transmission performed by the second plurality of wireless communication devices; and Before initiating the transmission of a reference signal by the first plurality of wireless communication devices using the additional transmission opportunity within the CoT associated with the second positioning group, it is confirmed that the first duration of the reference signal transmission is less than the CoT minus the second duration of the reference signal transmission.

30. The first wireless communication device of claim 29, wherein the processor is further configured to: Before initiating reference signal transmission by the first plurality of wireless communication devices using the additional transmission opportunities within the CoT associated with the second location group, a successful unobstructed channel assessment (CCA) is performed.

31. The first wireless communication device of claim 18, wherein the reference signal supports round-trip time (RTT) measurement between (a) at least one of the first plurality of wireless communication devices and (b) at least one of the second plurality of wireless communication devices.

32. The first wireless communication device of claim 18, wherein the processor is further configured to: Communicate with the second wireless communication device using a separate channel.

33. The first wireless communication device of claim 32, wherein the separate channel is located within the Intelligent Transmission System (ITS) band.

34. The first wireless communication device of claim 18, wherein the sidelink channel is located in unlicensed spectrum.

35. A first wireless communication device in a wireless communication network, comprising: A means for transmitting a first group forming broadcast message associated with a first location group, the first location group including a first plurality of wireless communication devices containing the first wireless communication device; A means for receiving a second group forming broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices containing a second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT including transmission opportunities configured for the second plurality of wireless communication devices to convey reference signals; as well as A means for initiating the transmission of a reference signal by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second location group in response to receiving a broadcast message of the second group formation.

36. A non-transient computer-readable medium storing instructions executable by one or more processing units, comprising instructions for the following operations: A first group of broadcast messages associated with a first location group is transmitted, the first location group including a first plurality of wireless communication devices containing a first wireless communication device; Receive a second group forming broadcast message associated with a second positioning group, the second positioning group including a second plurality of wireless communication devices containing a second wireless communication device, the second positioning group being associated with a channel occupancy time (CoT) in a sidelink channel, the CoT including transmission opportunities configured for the second plurality of wireless communication devices to convey reference signals; as well as In response to receiving the second group formation broadcast message, the transmission of reference signals is initiated by the first plurality of wireless communication devices using additional transmission opportunities within the CoT associated with the second positioning group.

Images