Estimating relative pose using lane markings

Abstract

Aspects relate to techniques for estimating relative pose using lane markings. A first wireless communication device may receive, from a second wireless communication device, a message including a plurality of visual features (e.g., keypoint) of an image captured by the second wireless communication device, a lane feature identifying two (or more) lane markings, and a respective two-point two-line (2L2P) metric for a keypoint pair based on the lane markings. The first wireless communication device may then obtain additional features from additional images captured by the first wireless communication device and identify matching key points for the additional features that meet the respective 2L2P metrics. The first wireless communication device may then calculate a relative pose of the first wireless communication device relative to the second wireless communication device based on the matching feature.

Description

[0001] Cross - Reference to Related Applications

[0002] This patent application claims priority to pending U.S. non - provisional application Ser. No. 18 / 082,860, filed on Dec. 16, 2022, which is assigned to the assignee of the present application and is hereby incorporated by reference in its entirety as if fully set forth herein and for all applicable purposes. Technical Field

[0003] The techniques discussed below generally relate to wireless communication networks and, more particularly, to relative pose determination between wireless communication devices. Background Art

[0004] Visual odometry can be used in various applications such as automotive applications. Visual odometry generally involves comparing consecutive image frames (e.g., in a video sequence) to infer the trajectory and pose of an object such as a vehicle. Pose refers to the translation of the vehicle (e.g., the geometric movement of the vehicle in two or three dimensions) and the orientation / rotation of the vehicle (e.g., pitch, yaw, roll). Visual odometry can be used, for example, in advanced driver assistance system (ADAS) applications to determine vehicle pose for collision avoidance, cooperative driving, and / or other vehicle safety features. Summary of the Invention

[0005] An overview of one or more aspects of the present disclosure is presented below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all contemplated features of the present disclosure and is neither intended to identify key or important elements of all aspects of the present disclosure nor to delineate the scope of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in a form as a prelude to the more detailed description that is presented later.

[0006] In one example, a first wireless communication device is disclosed. The first wireless communication device includes a transceiver, a memory, and a processor coupled to the transceiver and the memory. The processor is configured to receive, via the transceiver, lane features identifying two lane markings from a second wireless communication device, and to receive, via the transceiver, a plurality of first features in a first field of view associated with the second wireless communication device. Each first feature of the plurality of first features includes a respective first key point of a first image captured by the second wireless communication device. The processor is further configured to receive, via the transceiver, a respective two lines two points (2L2P) metric for each first key point pair within a set of first key point pairs of the plurality of first features based on the two lane markings, and to obtain a plurality of second features in a second field of view associated with the first wireless communication device. Each second feature of the plurality of second features includes a respective second key point of a second image captured by the first wireless communication device. The processor is further configured to: associate the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to the respective first key points within the plurality of first features; identify matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; and calculate a relative pose of the first wireless communication device relative to the second wireless communication device based on the matching key points.

[0007] Another example provides a method operable at a first wireless communication device. The method includes receiving lane features identifying two lane markings from a second wireless communication device, and receiving a plurality of first features in a first field of view associated with the second wireless communication device. Each first feature of the plurality of first features includes a respective first key point of a first image captured by the second wireless communication device. The method further includes receiving, from the second wireless communication device, a respective two lines two points (2L2P) metric for each first key point pair within a set of first key point pairs of the plurality of first features based on the two lane markings, and obtaining a plurality of second features in a second field of view associated with the first wireless communication device. Each second feature of the plurality of second features includes a respective second key point of a second image captured by the first wireless communication device. The method further includes: associating the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to the respective first key points within the plurality of first features; identifying matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; and calculating a relative pose of the first wireless communication device relative to the second wireless communication device based on the matching key points.

[0008] Another example provides a wireless communication device that includes a transceiver, a memory, and a processor coupled to the transceiver and the memory. The processor is configured to send, via the transceiver, lane features identifying two lane markings to at least one other wireless communication device, and to send, via the transceiver, a plurality of features in a field of view associated with the wireless communication device. Each feature of the plurality of features includes a respective key point of an image captured by the wireless communication device. The processor is further configured to send, via the transceiver, a respective two lines two points (2L2P) metric for each key point pair within a set of key point pairs of the plurality of features based on the two lane markings.

[0009] Another example provides a method that can be operated at a wireless communication device. The method includes sending lane features identifying two lane markings to at least one other wireless communication device, and sending a plurality of features in a field of view associated with the wireless communication device. Each feature of the plurality of features includes a respective key point of an image captured by the wireless communication device. The method further includes sending a respective two lines two points (2L2P) metric for each key point pair within a set of key point pairs of the plurality of features based on the two lane markings.

[0010] These and other aspects will be more fully understood after reading the following detailed description. After reading the following description of specific exemplary examples in conjunction with the accompanying drawings, other aspects, features, and examples will be apparent to those of ordinary skill in the art. Although the features may be discussed below with respect to certain examples and drawings, all examples may include one or more of the advantageous features discussed herein. In other words, although one or more examples may be discussed as having certain advantageous features, such features may be used, one or more at a time, in accordance with the various examples discussed herein. In a similar manner, although the exemplary examples may be discussed below as examples of devices, systems, or methods, such exemplary examples may be implemented in a variety of devices, systems, and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a diagram illustrating an example of a wireless radio access network in accordance with some aspects.

[0012] Figure 2 is a diagram illustrating an example of a frame structure for a wireless communication network in accordance with some aspects.

[0013] Figure 3 is a diagram illustrating an example of a wireless communication network employing side - link communication in accordance with some aspects.

[0014] Figure 4A and Figure 4B is a diagram illustrating an example of a side - link time slot structure in accordance with some aspects.

[0015] Figure 5 is a diagram illustrating an example of an image including key points according to some aspects.

[0016] Figure 6 is a diagram illustrating an example of relative pose determination between vehicles according to some aspects.

[0017] Figure 7 is a diagram illustrating an example of exemplary signaling between wireless communication devices for relative pose determination according to some aspects.

[0018] Figure 8 is a diagram illustrating an example of relative pose determination using key points from images captured at different cameras according to some aspects.

[0019] Figure 9 is a diagram illustrating an example of a low-texture environment according to some aspects.

[0020] Figure 10 is a diagram illustrating an example of 2L2P invariants according to some aspects.

[0021] Figure 11 is a diagram illustrating an example of relative pose determination utilizing lane markings according to some aspects.

[0022] Figure 12 is a block diagram illustrating an example of a hardware implementation for a wireless communication device employing a processing system according to some aspects.

[0023] Figure 13 is a flowchart of an exemplary process for relative pose determination utilizing lane markings according to some aspects.

[0024] Figure 14 is a flowchart of another exemplary process for relative pose determination utilizing lane markings according to some aspects.

[0025] Figure 15 is a flowchart of an exemplary process for visual feature sharing according to some aspects. Detailed Description

[0026] The detailed description set forth below in connection with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. For the purpose of providing a thorough understanding of the various concepts, the detailed description includes specific details. It will be apparent, however, to one of ordinary skill in the art that the concepts described herein may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0027] A mobile device equipped with a camera may be able to determine two-dimensional or three-dimensional displacements of the camera over time. For example, in automotive applications, visual odometry can be used to estimate the trajectory and pose of a vehicle. For some applications, such as advanced driver assistance systems (ADAS), high accuracy in relative vehicle pose determination (e.g., relative to another vehicle or object) can improve reaction times for lane changes, collision avoidance, and / or cooperative driving. In the absence of highly accurate relative pose determination, ADAS systems may be biased towards vehicles traveling straight in their lanes, which increases the reaction time for ADAS systems to react to lane changes. Due to the latency between image captures and field-of-view limitations, using only on-board cameras to determine relative vehicle pose may not meet the high accuracy requirements of ADAS systems.

[0028] To reduce the time taken to obtain relative vehicle pose and improve the accuracy of relative vehicle pose calculations, visual feature sharing can be performed between wireless communication devices to enable determination of the relative pose between the wireless communication devices. A first wireless communication device may send a request for visual feature sharing to a second wireless communication device and, in response, receive a message from the second wireless communication device that includes a plurality of features (e.g., first features) within a field of view (e.g., a first field of view) associated with the second wireless communication device. Each first feature may include a respective first key point of a first image captured by the second wireless communication device.

[0029] The first wireless communication device may then obtain a plurality of second features within a second field of view associated with the first wireless communication device. Each second feature may also include a respective second key point of a second image captured by the first wireless communication device. The first wireless communication device may calculate the relative pose of the first wireless communication device relative to the second wireless communication device based on the association between the plurality of first features and the plurality of second features.

[0030] In some examples, each feature (first feature and second feature) may also include a feature descriptor corresponding to the respective feature. The first wireless communication device may then calculate the relative pose by associating the first plurality of features with the second plurality of features based on the first / second key points and the corresponding first / second feature descriptors.

[0031] To reduce the number of visual features shared with a second wireless communication device and / or to enable the computation of a relative pose in a minimal texture environment that includes a relatively low number of different objects located near the wireless communication device, in various aspects of the present disclosure, lane markings on a road traveled by the wireless communication device can be utilized and used in conjunction with a reduced number of key points to obtain a relative pose between the wireless communication devices. For example, a second wireless communication device can send to a second wireless communication device lane features identifying the lane markings and a plurality of first features (e.g., first key points). For example, the plurality of first features provided by the second wireless communication device can include a subset of a larger set of first features obtained by the second wireless communication device in order to reduce overhead. In other examples, the plurality of first features can include all or most of the visual features obtained in a low texture environment. To utilize the lane markings and visual features to determine the relative pose, the second wireless communication device can also send a two-line two-point (2L2P) metric to the first wireless communication device.

[0032] The first wireless communication device can associate the plurality of first features with a plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to respective first key points within the plurality of first features. The first wireless communication can then identify matching key points within the set of corresponding key points that satisfy the respective 2L2P metric and compute the relative pose based on the matching key points.

[0033] While aspects and examples are described herein by way of illustration of some examples, those skilled in the art will understand that additional implementations and use cases can be generated in many different arrangements and scenarios. The innovations described herein can be implemented across many different platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, aspects and / or uses can be generated via integrated chip examples and other non-module component-based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / shopping devices, medical devices, AI-enabled devices, etc.). While some examples may or may not be specifically directed to a use case or application, a wide variety of applicability of the innovations described can occur. Implementations can range from chip-level or modular components to non-modular, non-chip-level implementations, and further to aggregated, distributed, or OEM devices or systems incorporating one or more aspects of the innovations described. In some practical settings, devices incorporating the aspects and features described may also necessarily include additional components and features for implementing and practicing the claimed and described examples. For example, the transmission and reception of wireless signals necessarily includes multiple components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.). The innovations described herein are intended to be practiced in various devices, chip-level components, systems, distributed arrangements, disaggregated arrangements (e.g., base stations and UEs), end-user devices, etc. of different sizes, shapes, and configurations.

[0034] The various concepts presented throughout this disclosure can be implemented across a wide variety of telecommunications systems, network architectures, and communication standards. Now referring to Figure 1 , by way of illustrative example and not limitation, a schematic diagram of a radio access network 100 is provided. The RAN 100 can implement any one or more suitable wireless communication technologies to provide radio access. As an example, the RAN 100 can operate according to the Third Generation Partnership Project (3GPP) New Radio (NR) specification (commonly referred to as 5G). As another example, the RAN 100 can operate according to a hybrid of 5G NR and the evolved Universal Terrestrial Radio Access Network (eUTRAN) standard (commonly referred to as LTE). 3GPP refers to this hybrid RAN as the next-generation RAN or NG-RAN. Of course, many other examples can be utilized within the scope of this disclosure.

[0035] The geographical area covered by the radio access network 100 can be divided into a plurality of cellular regions (cells), which can be uniquely identified by user equipment (UE) based on an identifier broadcast from one access point or base station over the geographical area. Figure 1Cells 102, 104, 106, and 108 are illustrated, and each of these cells may include one or more sectors (not shown). A sector is a sub-region of a cell. All sectors within a cell are served by the same base station. The radio link within a sector can be identified by a single logical identifier belonging to that sector. In a cell divided into sectors, multiple sectors within the cell can be formed by multiple sets of antennas, where each antenna is responsible for communicating with UEs in a part of the cell.

[0036] Generally, a corresponding base station (BS) serves each cell. Broadly speaking, a base station is a network entity in a radio access network that is responsible for radio transmission and reception to or from UEs in one or more cells. Those skilled in the art may also refer to the BS as a base transceiver station (BTS), radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), access point (AP), Node B (NB), evolved NB (eNB), 5G NB (gNB), transmission and reception point (TRP), or some other suitable term. In some examples, a base station may include two or more TRPs that may be co-located or non-co-located. Each TRP may communicate on the same or different carrier frequencies in the same or different frequency bands. In an example where RAN 100 operates according to both the LTE and 5G NR standards, one of the base stations in each base station may be an LTE base station, and the other base station may be a 5G NR base station. The base station may also be implemented in an aggregated or disaggregated architecture.

[0037] Various base station arrangements can be utilized. For example, in Figure 1 , base stations 110, 112, and 146 are shown in cells 102, 104, and 142; and another base station 114 is shown controlling a remote radio head (RRH) 116 in cell 106. That is, the base station may have an integrated antenna or may be connected to an antenna or RRH via a feeder cable. In the illustrated example, cells 102, 104, 106, and 142 may be referred to as macro cells because base stations 110, 112, 114, and 146 support cells with large sizes. Additionally, base station 118 is shown in cell 108 that may overlap with one or more macro cells. In this example, cell 108 may be referred to as a small cell (e.g., micro cell, pico cell, femto cell, home base station, home Node B, home eNode B, etc.) because base station 118 supports a cell with a relatively small range. Cell sizing can be performed according to system design and component constraints.

[0038] It should be understood that the radio access network 100 may include any number of radio base stations and cells. In addition, relay nodes may be deployed to extend the size or coverage area of a given cell. The base stations 110, 112, 114, 118, and 146 provide a wireless access point to the core network for any number of mobile devices.

[0039] Figure 1 It further includes an unmanned aerial vehicle (UAV) 120, which may be a drone or a quadcopter. The UAV 120 may be configured to act as a base station, or more specifically as a mobile base station. That is, in some examples, a cell may not necessarily be stationary, and the geographical area of the cell may move according to the position of a mobile base station such as the UAV 120.

[0040] Generally, a base station may include a backhaul interface for communicating with a backhaul portion (not shown) of the network. The backhaul may provide a link between the base station and the core network (not shown), and in some examples, the backhaul may provide an interconnection between the respective base stations. The core network may be part of a wireless communication system and may be independent of the radio access technology used in the radio access network. Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network.

[0041] The RAN 100 is illustrated as supporting wireless communication for multiple mobile devices. Mobile devices are commonly referred to as user equipment (UE) in the standards and specifications promulgated by the Third Generation Partnership Project (3GPP), but may also be referred to by those skilled in the art as a mobile station (MS), subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal (AT), mobile terminal, wireless terminal, remote terminal, cell phone, terminal, user agent, mobile client, client, or some other suitable term. A UE may be a device that provides a user with access to network services.

[0042] Within this document, a "mobile" device does not necessarily need to have the ability to move and it can be stationary. The term mobile device or mobile equipment refers to a wide variety of devices and technologies. For example, some non-limiting examples of mobile devices include mobile stations, cellular (cell) phones, smart phones, Session Initiation Protocol (SIP) phones, laptop computers, personal computers (PCs), notebooks, netbooks, smartbooks, tablet devices, personal digital assistants (PDAs), and a wide range of embedded systems, such as those corresponding to the "Internet of Things" (IoT). A mobile device can additionally be an automobile 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-axis aircraft, a quadcopter, a remote control device, a consumer and / or wearable device (such as glasses, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., an MP3 player), a camera, a game console, etc.). A mobile device can additionally be a digital home or smart home device (such as a home audio, video, and / or multimedia device), an 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 that controls electric power (e.g., a smart grid), lighting, water supply, etc., an industrial automation and enterprise device, a logistics controller, and / or an agricultural equipment, etc. Additionally, a mobile device can provide connected medical or telemedicine support, such as healthcare at a distance. Telehealth devices can include telehealth monitoring devices and telehealth regulatory devices, and their communication can be given prioritized access over other types of information, for example, in the form of prioritized access for critical service data transmission and / or associated QoS for critical service data transmission.

[0043] Within the RAN 100, a cell can include UEs that can communicate with one or more sectors of each cell. For example, UEs 122 and 124 can communicate with base station 110; UEs 126 and 128 can communicate with base station 112; UEs 130 and 132 can communicate with base station 114 via RRH 116; UEs 138 and 140 can communicate with base station 146; and UE 136 can communicate with mobile base station 120. Here, each of base stations 110, 112, 114, 118, 120, and 146 can be configured to provide an access point to a core network (not shown) for all UEs in the corresponding cell. In another example, a mobile network node (e.g., UAV120) can be configured to act as a UE. For example, UAV 120 can operate within cell 102 by communicating with base station 110.

[0044] In RAN 100, the ability of a UE to communicate while moving (regardless of its location) is referred to as mobility. The various physical channels between the UE and the RAN are generally established, maintained, and released under the control of an access and mobility management function (AMF), which may include a security context management function (SCMF) that manages the security context for both the control plane and user plane functionality and a security anchor function (SEAF) that performs authentication. In some examples, during a call with a scheduling entity or at any other time, the UE may monitor various parameters of the signals from its serving cell as well as various parameters of neighboring cells. Based on the quality of these parameters, the UE may maintain communication with one or more neighboring cells. During this time, if the UE moves from one cell to another or if the signal quality from a neighboring cell exceeds the signal quality from the serving cell for a given amount of time, the UE may perform a handover or handoff from the serving cell to the neighboring (target) cell. For example, UE 124 may move from the geographical area corresponding to its serving cell 102 to the geographical area corresponding to neighboring cell 106. When the signal strength or quality from neighboring cell 106 exceeds the signal strength and quality of its serving cell 102 for a given amount of time, UE 124 may send a report message to its serving base station 110 indicating this situation. In response, UE 124 may receive a handover command, and the UE may perform a handover to cell 106.

[0045] The wireless communication between RAN 100 and a UE (e.g., UE 122 or 124) can be described as utilizing an air interface. Transmissions from a base station (e.g., base station 110) to one or more UEs (e.g., UE 122 and 124) via the air interface can be referred to as downlink (DL) transmissions. According to certain aspects of the present disclosure, the term "downlink" may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station 110). Another way to describe this scenario may be 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. According to additional aspects of the present disclosure, the term "uplink" may refer to a point-to-point transmission originating at a scheduled entity (described further below; e.g., UE 122).

[0046] For example, DL transmissions can include unicast or broadcast transmissions of control information and / or data (e.g., user data traffic or other types of traffic) from a base station (e.g., base station 110) to one or more UEs (e.g., UEs 122 and 124), while UL transmissions can include transmissions of control information and / or traffic information originating at a UE (e.g., UE 122). Additionally, uplink and / or downlink control information and / or traffic information can be time-divided into frames, subframes, time slots, and / or symbols. As used herein, a symbol can refer to a time unit that carries one resource element (RE) per subcarrier in an orthogonal frequency-division multiplexing (OFDM) waveform. A time slot can carry 7 or 14 OFDM symbols. A subframe can refer to a duration of 1 ms. Multiple subframes or time slots can be grouped together to form a single frame or radio frame. Within the present disclosure, a frame can refer to a predetermined duration for wireless transmission (e.g., 10 ms), where each frame, for example, consists of 10 subframes each being 1 ms. Of course, these definitions are not required, and any suitable scheme for organizing the waveform can be utilized, and the various time divisions of the waveform can have any suitable duration.

[0047] The air interface in RAN 100 can utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of various devices. For example, the 5G NR specification provides multiple access for UL or reverse link transmissions from UEs 122 and 124 to base station 110, and multiplexes DL or forward link transmissions from base station 110 to UEs 122 and 124 using orthogonal frequency-division multiplexing (OFDM) with a cyclic prefix (CP). Additionally, for UL transmissions, the 5G NR specification provides support for discrete Fourier transform spread OFDM (DFT-s-OFDM) with CP (also known 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 provided using time-division multiple access (TDMA), code-division multiple access (CDMA), frequency-division multiple access (FDMA), sparse code multiple access (SCMA), resource spreading multiple access (RSMA), or other suitable multiple access schemes. Furthermore, 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 can be utilized to provide multiplexing for DL transmissions from base station 110 to UEs 122 and 124.

[0048] In addition, the air interface in RAN 100 may utilize one or more duplexing algorithms. Duplexing refers to a point-to-point communication link where two endpoints can communicate with each other in two directions. Full duplex means that two endpoints can communicate with each other simultaneously. Half duplex means that only one endpoint can transmit information to the other endpoint at a time. Half duplex emulation is often implemented using time division duplex (TDD) for wireless links. In TDD, transmissions in different directions on a given channel are separated from each other using time division multiplexing. That is, at some times, the channel is dedicated to transmission in one direction, while at other times, the channel is dedicated to transmission in the other direction, where the direction can change very rapidly, e.g., several times per time slot. In a wireless link, a full duplex channel generally relies on physical isolation of the transmitter and receiver and appropriate interference cancellation techniques. Full duplex emulation is often implemented for wireless links by utilizing frequency division duplex (FDD) or space division duplex (SDD). In FDD, transmissions in different directions can operate at different carrier frequencies (e.g., within paired spectra). In SDD, space division multiplexing (SDM) is used to separate transmissions in different directions on a given channel. In other examples, full duplex communication can be achieved within unpaired spectra (e.g., within a single carrier bandwidth), where transmissions in different directions occur in different subbands of the carrier bandwidth. This type of full duplex communication may be referred to herein as subband full duplex (SBFD), also known as flexible duplex (FD).

[0049] In various embodiments, the air interface in RAN 100 may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum typically provides exclusive use of a portion of the spectrum by a mobile network operator by purchasing a license from a government regulatory agency. Unlicensed spectrum provides shared use of a portion of the spectrum without the need for a license granted by the government. Although some technical rules usually still need to be complied with to access unlicensed spectrum, generally any operator or device can obtain access. Shared spectrum can fall between licensed spectrum and unlicensed spectrum, where some technical rules or restrictions may be required to access the spectrum, but the spectrum can still be shared by multiple operators and / or multiple RATs. For example, the license holder of a portion of licensed spectrum may provide licensed shared access (LSA) to share the spectrum with other parties (e.g., with appropriate licensee-determined conditions to obtain access).

[0050] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as Frequency Range Designation FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). It should be understood that although part of FR1 is greater than 6 GHz, in various documents and articles, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band. Referring to FR2, a similar naming issue sometimes occurs, which is typically (interchangeably) referred to as the "millimeter wave" band in documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz - 300 GHz) identified by the International Telecommunication Union (ITU) as the "millimeter wave" band.

[0051] The frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands for these mid-band frequencies as Frequency Range Designation FR3 (7.125 GHz - 24.25 GHz). The bands falling within FR3 can inherit FR1 characteristics and / or FR2 characteristics, and thus can effectively extend the features of FR1 and / or FR2 to the mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations beyond 52.6 GHz. For example, three higher operating bands have been identified as Frequency Range Designation FR4-a or FR4-1 (52.6 GHz - 71 GHz), FR4 (52.6 GHz - 114.25 GHz), and FR5 (114.25 GHz - 300 GHz). Each of these higher frequency bands falls within the EHF band.

[0052] Taking the above aspects into account, unless otherwise specifically stated, it should be understood that if used in this document, terms such as "sub-6 GHz" can generally represent frequencies that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise specifically stated, it should be understood that if terms such as "millimeter wave" are used in this document, they can generally represent frequencies that can include mid-band frequencies, can be within FR2, FR4, FR4-a or FR4-1, and / or FR5, or can be within the EHF band.

[0053] To obtain a low block error rate (BLER) for transmissions over the air interface while still achieving a very high data rate, channel decoding can be used. That is, wireless communication can generally utilize a suitable error-correcting block code. In a typical block code, an information message or sequence is split into code blocks (CBs), and an encoder (e.g., codec) at the transmitting device then mathematically adds redundancy to the information message. Utilizing this redundancy in the encoded information message can improve the reliability of the message, enabling the correction of any bit errors that may occur due to noise.

[0054] Data decoding can be implemented in a variety of ways. In the early 5G NR specifications, quasi-cyclic low-density parity-check (LDPC) is used to decode user data using two different base graphs: one base graph is used for large code blocks and / or high code rates, and another base graph is used for other cases. Polar decoding is used to decode control information and the physical broadcast channel (PBCH) based on nested sequences. For these channels, puncturing, shortening, and repetition are used for rate matching.

[0055] Aspects of the present disclosure can be implemented using any suitable channel code. Various specific implementations of the base station and the UE may include suitable hardware and capabilities (e.g., encoders, decoders, and / or codecs) to perform wireless communication using one or more of these channel codes.

[0056] In some examples, access to the air interface can be scheduled, where a scheduling entity (e.g., base station 112) allocates resources for communication among some or all of the devices and equipment within its service area or cell. Within the present disclosure, as further discussed below, 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 (e.g., UE 126), which can be a scheduled entity, can utilize the resources allocated by the scheduling entity 112.

[0057] The base station is not the only entity that can act as a scheduling entity. That is, in some examples, a UE can act as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). For example, two or more UEs (e.g., UE 138 and UE 140) can communicate with each other using peer-to-peer (P2P) or sidelink signals 137 without relaying the communication through a base station (e.g., base station 146). In some examples, UE 138 and 140 can each act as a scheduling entity or a transmitting sidelink device and / or a scheduled entity or a receiving sidelink device to communicate the sidelink signal 137 between them without relying on scheduling or control information from a base station (e.g., base station 146). In other examples, the base station 146 can allocate resources to UE 138 and 140 for sidelink communication. For example, UE 138 and 140 can use sidelink signaling to communicate in a P2P network, a device-to-device (D2D) network, a vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X), a mesh network, or other suitable networks.

[0058] In some examples, a D2D relay framework can be included within a cellular network to facilitate relaying of communications to / from a base station 112 via a D2D link (e.g., sidelink 137). For example, one or more UEs (e.g., UE 138) within the coverage area of base station 146 can operate as relay UEs to extend the coverage of base station 146, improve transmission reliability to one or more UEs (e.g., UE 140), and / or allow the base station to recover from a failed UE link due to, for example, blockage or fading.

[0059] Two main technologies that can be used by V2X networks include dedicated short range communications (DSRC) based on the IEEE 802.11p standard and cellular V2X based on LTE and / or 5G (New Radio) standards. For simplicity, various aspects of the present disclosure may relate to a New Radio (NR) cellular V2X network, referred to herein as a V2X network. However, it should be understood that the concepts disclosed herein may not be limited to a particular V2X standard or may refer to sidelink networks other than V2X networks.

[0060] Reference will be made Figure 2 to the OFDM waveform schematically illustrated to describe various aspects of the present disclosure. Those skilled in the art should understand that the various aspects of the present disclosure can be applied to SC-FDMA waveforms in substantially the same manner as described hereinbelow. That is, although for clarity some examples of the present disclosure may focus on OFDM links, it should be understood that the same principles can also be applied to SC-FDMA waveforms.

[0061] Now referring Figure 2 , an expanded view of an exemplary subframe 202 is illustrated, which shows an OFDM resource grid. However, as will be readily apparent to those skilled in the art, the PHY transmission structure for any particular application may differ from the examples described herein, depending on any number of factors. Here, time is in the horizontal direction in terms of OFDM symbols; and frequency is in the vertical direction in terms of the subcarriers of a carrier.

[0062] The resource grid 204 can be used to schematically represent time-frequency resources for a given antenna port. That is, in a multiple-input multiple-output (MIMO) implementation with multiple available antenna ports, the corresponding multiple resource grids 204 can be available for communication. The resource grid 204 is divided into multiple resource elements (REs) 206. An RE (which is 1 subcarrier × 1 symbol) is the smallest discrete part of the time-frequency grid and contains a single complex value representing data from a physical channel or signal. Depending on the modulation utilized in a particular implementation, each RE can represent one or more information bits. In some examples, a block of REs may be referred to as a physical resource block (PRB), or more simply as a resource block (RB) 208, which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers (a number independent of the parameter set used). In some examples, depending on the parameter set, an RB may include any suitable number of consecutive OFDM symbols in the time domain. Within this disclosure, it is assumed that a single RB (such as RB 208) fully corresponds to communication in a single direction (transmission or reception for a given device).

[0063] A set of consecutive or non-consecutive resource blocks may be referred to herein as a resource block group (RBG), subband, or bandwidth part (BWP). A set of subbands or BWPs may span the entire bandwidth. Scheduling of a UE or side-link device (collectively referred to hereinafter as UE) for downlink, uplink, or side-link transmission generally involves scheduling one or more resource elements 206 within one or more subbands or bandwidth parts (BWPs). Thus, a UE generally utilizes only a subset of the resource grid 204. In some examples, an RB may be the smallest resource unit that can be allocated to a UE. Thus, the more RBs scheduled for a UE, and the higher the modulation scheme selected for the air interface, the higher the data rate for the UE. RBs can be scheduled by a base station (e.g., gNB, eNB, etc.), or can be self-scheduled by a UE / side-link device implementing D2D side-link communication.

[0064] In this illustration, RB 208 is shown as occupying less than the entire bandwidth of subframe 202, with some subcarriers illustrated above and below RB 208. In a given implementation, subframe 202 may have a bandwidth corresponding to any number of one or more RBs 208. Additionally, in this illustration, RB 208 is shown as occupying less than the entire duration of subframe 202, although this is only one possible example.

[0065] Each 1 ms subframe 202 may be composed of one or more adjacent time slots. In Figure 2In the example shown, as an illustrative example, a subframe 202 includes four time slots 210. In some examples, a time slot may be defined according to a specified number of OFDM symbols with a given cyclic prefix (CP) length. For example, a time slot may include 7 or 12 OFDM symbols with a nominal CP. Additional examples may include mini-slots (sometimes referred to as shortened transmission time intervals (TTIs)) having a shorter duration (e.g., one to three OFDM symbols). These mini-slots or shortened transmission time intervals (TTIs) may in some cases be transmitted by occupying resources scheduled for an ongoing time slot transmission for the same UE or a different UE. Any number of resource blocks may be utilized within a subframe or a time slot.

[0066] An expanded view of one of the time slots 210 illustrates that the time slot 210 includes a control region 212 and a data region 214. Generally, the control region 212 may carry a control channel, and the data region 214 may carry a data channel. Of course, a time slot may contain all DL, all UL, or at least one DL portion and at least one UL portion. Figure 2 The structures illustrated herein are merely exemplary in nature, and different time slot structures may be utilized, and these time slot structures may include one or more regions in each of the control region and the data region.

[0067] Although not illustrated in Figure 2 Various resource elements (REs) 206 within the resource block (RB) 208 may be scheduled to carry one or more physical channels, which may include a control channel, a shared channel, a data channel, etc. Other REs 206 within the RB 208 may also carry pilot signals or reference signals. These pilot signals or reference signals may be provided to a receiving device to perform channel estimation of a corresponding channel, which may enable coherent demodulation / detection of a control channel and / or a data channel within the RB 208.

[0068] In some examples, the time slot 210 may be utilized for broadcast, multicast, groupcast, or unicast communication. For example, broadcast, multicast, or groupcast communication may refer to a point-to-multipoint transmission from one device (e.g., a base station, a UE, or other similar device) to other devices. Herein, broadcast communication is delivered to all devices, while multicast or groupcast communication is delivered to multiple intended receiving devices. Unicast communication may refer to a point-to-point transmission from one device to a single other device.

[0069] In an example of cellular communication over a cellular carrier via the Uu interface, for DL transmission, a scheduling entity (e.g., a base station) may allocate one or more REs 206 (e.g., within the control region 212) to one or more scheduled entities (e.g., UEs) to carry DL control information including one or more DL control channels such as the Physical Downlink Control Channel (PDCCH). The PDCCH carries Downlink Control Information (DCI), including but not limited to power control commands (e.g., one or more open-loop power control parameters and / or one or more closed-loop power control parameters), scheduling information, grants, and / or assignments of REs for DL transmission and UL transmission. The PDCCH may also carry HARQ feedback transmissions such as an acknowledgement (ACK) or a negative acknowledgement (NACK). HARQ is a technique well known to those of ordinary skill in the art, where the integrity of a packet transmission can be verified for accuracy at the receiving side, e.g., using any suitable integrity verification mechanism such as a checksum or a Cyclic Redundancy Check (CRC). If the integrity of the transmission is confirmed, an ACK may be sent, while if it is not confirmed, a NACK may be sent. In response to a NACK, the transmitting device may transmit a HARQ retransmission, which may implement Chase Combining, Incremental Redundancy, etc.

[0070] The base station may also allocate one or more REs 206 (e.g., in the control region 212 or the data region 214) to carry other DL signals such as Demodulation Reference Signals (DMRS); Phase Tracking Reference Signals (PT-RS); Channel State Information (CSI) Reference Signals (CSI-RS); and Synchronization Signal Blocks (SSB). The SSB may be broadcast at regular intervals based on a period (e.g., 5 ms, 10 ms, 20 ms, 20 ms, 80 ms, or 120 ms). The SSB includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Physical Broadcast Control Channel (PBCH). The UE may use the PSS and SSS to achieve radio frame, subframe, slot, and symbol synchronization in the time domain, identify the center of the channel (system) bandwidth in the frequency domain, and identify the Physical Cell Identity (PCI) of the cell.

[0071] The PBCH in SSB may also include a master information block (MIB) containing various system information and parameters for decoding system information blocks (SIBs). The SIB can be, for example, SystemInformationType 1 (SIB1), which may include various additional system information. The MIB and SIB1 together provide the minimum system information (SI) for initial access. Examples of the system information sent in the MIB may include, but are not limited to, subcarrier spacing (e.g., default downlink parameter set), system frame number, configuration of the PDCCH control resource set (CORESET) (e.g., PDCCH CORESET0), cell barring indicator, cell reselection indicator, grid offset, and search space for SIB1. Examples of the remaining minimum system information (RMSI) sent in SIB1 may include, but are not limited to, random access search space, paging search space, downlink configuration information, and uplink configuration information.

[0072] In UL transmission, the scheduled entity (e.g., UE) may utilize one or more REs 206 to the scheduled entity to carry UL control information (UCI) including one or more UL control channels such as the physical uplink control channel (PUCCH). The UCI may include various packet types and categories, including pilots, reference signals, and information configured to enable or assist in decoding uplink data transmissions. Examples of uplink reference signals may include sounding reference signals (SRS) and uplink DMRS. In some examples, the UCI may include a scheduling request (SR), i.e., a request to the scheduled entity to schedule an uplink transmission. Herein, in response to the SR sent on the UCI, the scheduled entity may send downlink control information (DCI), which may schedule resources for uplink packet transmission. The UCI may also include HARQ feedback, channel state feedback (CSF) (such as CSI report), or any other suitable UCI.

[0073] In addition to control information, one or more REs 206 (e.g., within the data region 214) may also be allocated for data traffic. Such data traffic may be carried on one or more traffic channels, such as for DL transmission, carried on the physical downlink shared channel (PDSCH); or for UL transmission, carried on the physical uplink shared channel (PUSCH). In some examples, one or more REs 206 within the data region 214 may be configured to carry other signals, such as one or more SIBs and DMRS.

[0074] In an example of sidelink communication via a sidelink carrier over the PC5 interface, the control region 212 of slot 210 may include a Physical Sidelink Control Channel (PSCCH) that includes sidelink control information (SCI) transmitted by an initiating (transmitting) sidelink device (e.g., a Tx V2X device or other Tx UE) to a set of one or more other receiving sidelink devices (e.g., an Rx V2X device or other Rx UE). The data region 214 of slot 210 may include a Physical Sidelink Shared Channel (PSSCH) that includes sidelink data traffic transmitted by the initiating (transmitting) sidelink device within resources reserved on the sidelink carrier via the SCI. Other information may also be transmitted via various REs 206 within slot 210. For example, HARQ feedback information may be transmitted from the receiving sidelink device to the transmitting sidelink device in a Physical Sidelink Feedback Channel (PSFCH) within slot 210. Additionally, one or more reference signals (such as a sidelink SSB, sidelink CSI-RS, sidelink SRS, sidelink DMRS, and / or sidelink positioning reference signal (PRS)) may be transmitted within slot 210.

[0075] These physical channels described above are typically multiplexed and mapped to transport channels for handling at the Medium Access Control (MAC) layer. The transport channels carry information blocks called transport blocks (TBs). Based on the Modulation and Coding Scheme (MCS) and the number of RBs in a given transmission, the transport block size (TBS) (which may correspond to the number of information bits) can be a controlled parameter.

[0076] Figure 2 The illustrated channels or carriers are not necessarily all the channels or carriers that may be utilized between devices, and one of ordinary skill in the art will recognize that other channels or carriers, such as other traffic channels, control channels, and feedback channels, may be utilized in addition to those illustrated.

[0077] Figure 3An example of a wireless communication network 300 configured to support sidelink communication is illustrated. In some examples, sidelink communication may include D2D or V2X communication. V2X communication involves not only direct wireless information exchange between vehicles (e.g., vehicles 302 and 304) themselves, but also direct wireless information exchange between vehicles 302 / 304 and infrastructure (e.g., roadside unit (RSU) 306) (such as street lights, buildings, traffic cameras, toll booths, or other stationary objects), between vehicles 302 / 304 and pedestrians 308, and between vehicles 302 / 304 and the wireless communication network (e.g., network entity 310). The network entity 310 may be further implemented in an aggregated or monolithic base station architecture or in a disaggregated base station architecture. Additionally, the network entity 310 may be a stationary network entity or a mobile network entity. In some examples, V2X communication may be implemented according to the new radio (NR) cellular V2X standard defined by 3GPP (Release 16) or other suitable standards.

[0078] V2X communication enables vehicles 302 and 304 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 and enhance vehicle safety. For example, such V2X data enables autonomous driving and improves road safety and traffic efficiency. For example, V2X-connected vehicles 302 and 304 may utilize the exchanged V2X data to provide collision warnings in the vehicle, road hazard warnings, warnings for approaching emergency vehicles, pre-impact / post-impact warnings and information, emergency braking warnings, warnings for traffic jams ahead, lane change warnings, intelligent navigation services, and other similar information. Additionally, V2X data received by V2X-connected mobile devices of pedestrians / cyclists 308 can be used to trigger warning sounds, vibrations, flashlights, etc. in case of impending danger.

[0079] Sidelink communication between vehicle UEs (V-UEs) 302 and 304, or between V-UE 302 or 304 and RSU 306 or pedestrian UE (P-UE) 308, may occur over the proximity service (ProSe) PC5 interface via sidelink 312. In various aspects of the present disclosure, the PC5 interface may be further used to support D2D sidelink 312 communication in other proximity use cases (e.g., other than V2X). Examples of other proximity use cases may include smart wearable devices, public safety, or commerce-based (e.g., entertainment, education, office, medical, and / or interaction) proximity services. In Figure 3 In the example shown, ProSe communication may also occur between UEs 314, 316, and 318.

[0080] ProSe communication can support different operation scenarios, such as in-coverage, out-of-coverage, and partial coverage. Out-of-coverage means a scenario where UEs (e.g., UEs 314 and 316) are outside the coverage area of a network entity (e.g., network entity 310) but are each still configured for ProSe communication. Partial coverage means a scenario where some of the UEs (e.g., V-UE 304) are outside the coverage area of network entity 310 while other UEs (e.g., V-UE 302 and P-UE 308) communicate with network entity 310. In-coverage refers to a scenario where UEs (e.g., V-UE 302 and P-UE 308) communicate with network entity 310 (e.g., gNB) via a Uu (e.g., cellular interface) connection to receive ProSe service authorization and provisioning information to support ProSe operations.

[0081] In some examples, a UE (e.g., UE 318) may not have a Uu connection to network entity 310. In this example, a D3D relay link (on sidelink 312) may be established between UE 318 and UE 314 to relay communication between UE 318 and network entity 310. The relay link may utilize decode-and-forward (DF) relay, amplify-and-forward (AF) relay, or compress-and-forward (CF) relay. For DF relay, HARQ feedback may be provided from the receiving device to the transmitting device. Sidelink communication on the relay link may be carried, for example, in the licensed frequency domain using radio resources operating according to 5G NR or NR sidelink (SL) specifications and / or in the unlicensed frequency domain using radio resources operating according to 5G New Radio Unlicensed (NR-U) specifications. The relay link between UE 314 and UE 318 may be established due to, for example, the distance or signal blockage between network entity 310 and UE 318, the weak reception ability of UE 318, the low transmission power of UE 318, the limited battery capacity of UE 318, and / or to improve link diversity. Thus, the relay link may enable communication between network entity 310 and UE 318 to be relayed over a Uu radio communication link and a relay link (e.g., between UE 314 and UE 318) via one or more relay UEs (e.g., UE 314). In other examples, the relay link may enable sidelink communication to be relayed between a UE (e.g., UE 318) and another UE (e.g., UE 316) via various relay links (e.g., relay links between UE 314 and UE 316 and between UE 314 and UE 318).

[0082] To facilitate D2D sidelink communication between, for example, UEs 314 and 316 via sidelink 312, UEs 314 and 316 may send discovery signals between them. In some examples, each discovery signal may include synchronization signals, such as a primary synchronization signal (PSS) and / or a secondary synchronization signal (SSS), which facilitate device discovery and synchronization of communication on sidelink 312. For example, the discovery signal may be used by UE 316 to measure the signal strength and channel state of a potential sidelink (e.g., sidelink 312) with another UE (e.g., UE 314). UE 316 may utilize these measurements to select a UE (e.g., UE 314) for sidelink communication or relay communication.

[0083] In some examples, a common carrier may be shared between sidelink 312 and the Uu link such that resources on the common carrier may be allocated for sidelink communication between UEs (e.g., UEs 302, 304, 307, 308, 314, 316, and 318) and cellular communication (e.g., uplink and downlink communication) between UEs (e.g., UEs 302, 304, 306, 308, 314, 316, and 318) and network entity 310. In 5G NR sidelink, sidelink communication may utilize transmit or receive resource pools. For example, the smallest resource allocation unit in frequency may be a subchannel (e.g., which may include, for example, 10, 15, 20, 25, 50, 75, or 100 consecutive RBs), and the smallest resource allocation unit in time may be a time slot. The number of subchannels in a resource pool may include between one and twenty-seven. The configuration of a resource pool (RP) for communication between two sidelink devices may be pre-configured (e.g., factory settings determined, for example, by sidelink standards or specifications on the UE) or provided by a network entity (e.g., network entity 310).

[0084] In addition, sidelink (e.g., PC5) communication can have two main resource allocation operation modes. In the first mode (Mode 1), a network entity (e.g., gNB) 310 can allocate resources to sidelink devices (e.g., V2X devices or other sidelink devices) for sidelink communication between the sidelink devices in various ways. For example, the network entity 310 can dynamically allocate sidelink resources (e.g., dynamic grant) to a sidelink device in response to a request for sidelink resources from the sidelink device. For example, the network entity 310 can schedule sidelink communication via DCI 3_0. In some examples, the network entity 310 can schedule PSCCH / PSSCH within the uplink resources indicated in DCI 3_0. The network entity 310 can also activate a pre-configured sidelink grant (e.g., configured grant) for sidelink communication between sidelink devices. In some examples, the network entity 310 can activate a configured grant (CG) via RRC signaling. In Mode 1, the sidelink feedback can be reported back to the network entity 310 by the transmitting sidelink device.

[0085] In the second mode (Mode 2), the sidelink devices can autonomously select sidelink resources for sidelink communication between them. In some examples, the transmitting sidelink device can perform resource / channel sensing to select an unoccupied resource (e.g., sub-channel) on the sidelink channel. The signaling on the sidelink is the same between these two modes. Therefore, from the perspective of the receiver, there is no difference between these modes.

[0086] In some examples, sidelink (e.g., PC5) communication can be scheduled by using sidelink control information (SCI). The SCI can include two SCI phases. The sidelink control information of Phase 1 (first-phase SCI) can be referred to as SCI-1 in this document. The sidelink control information of Phase 2 (second-phase SCI) can be referred to as SCI-2 in this document.

[0087] SCI-1 can be transmitted on the Physical Sidelink Control Channel (PSCCH). SCI-1 can include resource allocation for sidelink resources and information for decoding sidelink control information in the second phase (i.e., SCI-2). For example, SCI-1 can include Physical Sidelink Shared Channel (PSSCH) resource assignment and resource reservation period (if enabled). SCI-1 can also identify the priority level of the PSSCH (e.g., Quality of Service (QoS)). For example, Ultra-Reliable Low-Latency Communication (URLLC) services can have a higher priority than short message services (e.g., Short Message Service (SMS) services). Additionally, SCI-1 can include the PSSCH Demodulation Reference Signal (DMRS) pattern (if more than one pattern is configured). The DMRS can be used by the receiver for radio channel estimation for demodulating the associated physical channel. As indicated, SCI-1 can also include information about SCI-2. For example, SCI-1 can disclose the format of SCI-2. Here, the format indicates the resource size of SCI-2 (e.g., the number of Resource Elements (REs) allocated for SCI-2), the number of PSSCH DMRS ports, and the Modulation and Coding Scheme (MCS) index. In some examples, SCI-1 can use two bits to indicate the SCI-2 format. Thus, in this example, four different SCI-2 formats can be supported. SCI-1 can include other information useful for establishing and decoding PSSCH resources.

[0088] SCI-2 can be transmitted on the PSSCH and can contain information for decoding the PSSCH. According to some aspects, SCI-2 includes a 16-bit Layer 1 (L1) destination identifier (ID), an 8-bit L1 source ID, a Hybrid Automatic Repeat reQuest (HARQ) process ID, a New Data Indicator (NDI), and a Redundancy Version (RV). For unicast communication, SCI-2 can also include a CSI report trigger. For multicast communication, SCI-2 can also include a zone identifier and the maximum communication range of NACKs. SCI-2 can include other information useful for establishing and decoding PSSCH resources.

[0089] In some examples, the SCI (e.g., SCI-1 and / or SCI-2) can also include resource assignments for one or more retransmissions (e.g., sidelink traffic / data) for sidelink transmission or resources reserved for one or more additional (new) sidelink transmissions. Thus, the SCI can include corresponding PSSCH resource reservations and assignments for one or more PSSCH transmissions. For example, the SCI can include a reservation message that indicates the PSSCH resource reservation for an initial sidelink transmission (initial PSSCH) and one or more additional PSSCH resource reservations for one or more retransmissions of the PSSCH.

[0090] Figure 4A andFigure 4B is a diagram illustrating an example of a sidelink slot structure according to some aspects. For example, this sidelink slot structure can be utilized in a V2X or other D2D network implementing sidelinks. In Figure 4A and Figure 4B the example shown, time is in the horizontal direction, in units of symbol 402 (e.g., OFDM symbol); and frequency is in the vertical direction. Here, the carrier bandwidth 404 allocated for sidelink wireless communication is illustrated along the frequency axis. The carrier bandwidth 404 can include multiple subchannels, where each subchannel can include a configurable number of PRBs (e.g., 10, 15, 20, 25, 50, 75, or 100 PRBs).

[0091] Figure 4A and Figure 4B illustrate examples of corresponding slots 400a or 400b, respectively, which include fourteen symbols 402 that can be used for sidelink communication. However, it should be understood that sidelink communication can be configured to occupy fewer than fourteen symbols in slot 400a or 400b, and the present disclosure is not limited to any specific number of symbols 402. Each sidelink slot 400a and 400b includes a Physical Sidelink Control Channel (PSCCH) 406 that occupies the control region 418 of slots 400a and 400b and a Physical Sidelink Shared Channel (PSSCH) 408 that occupies the data region 420 of slots 400a and 400b. The PSCCH 406 and PSSCH 408 are each transmitted on one or more symbols 402 of slot 400a. The PSCCH 406 includes, for example, a SCI-1 (e.g., SCI format 1-A) that schedules the transmission of data traffic (e.g., packets) on the time-frequency resources of the corresponding PSSCH 408. As Figure 4A and Figure 4B shown, the PSCCH 406 and the corresponding PSSCH 408 are transmitted in the same slots 400a and 400b. In some examples, the PSCCH 406 can schedule the PSSCH in subsequent slots.

[0092] In some examples, the PSCCH 406 is configured to last for two or three symbols. Additionally, the PSCCH 406 can be configured to span a configurable number of PRBs, limited to a single subchannel. For a resource pool, the PSCCH resource size can be fixed (e.g., 10% to 100% of one subchannel in the first two or three symbols). For example, the PSCCH 406 can occupy 10, 12, 15, 20, or 25 RBs of a single subchannel. In Figure 4A and Figure 4BIn each of the examples shown, the starting symbol of the PSCCH 406 is the second symbol of the corresponding time slot 400a or 400b, and the PSCCH 406 spans three symbols 402. The PSCCH 406 may also include DMRS.

[0093] The PSSCH 408 may be time-division multiplexed (TDM) with the PSCCH 406 and / or frequency-division multiplexed (FDM) with the PSCCH 406. In Figure 4A the example shown, the PSSCH 408 includes a first part 408a that is TDM with the PSCCH 406 and a second part 408b that is FDM with the PSCCH 406. In Figure 4B the example shown, the PSSCH 408 is TDM with the PSCCH 406.

[0094] One-layer transmission and two-layer transmission of the PSSCH 408 can be supported by various modulation orders (e.g., QPSK, 16-QAM, 64-QAM, and 256-QAM). In addition, the PSSCH 408 may include DMRS 414 configured in a two-symbol, three-symbol, or four-symbol DMRS pattern. For example, Figure 4A the time slot 400a shown illustrates a two-symbol DMRS pattern, while Figure 4B the time slot 400b shown illustrates a three-symbol DMRS pattern. In some examples, the transmitting UE can select the DMRS pattern according to the channel condition and indicate the selected DMRS pattern in the SCI-1. The DMRS pattern can be selected, for example, based on the number of PSSCH 408 symbols in the time slot 400a or 400b. In some examples, the DMRS 414 may be based on a Gold sequence, and Configuration Type 1 can be used for the frequency-domain pattern of the PSSCH DMRS 414. In addition, in each of the time slots 400a and 400b, there is a gap symbol 416 after the PSSCH 408.

[0095] Each of the time slots 400a and 400b also includes an SCI-2 412 that is mapped to consecutive RBs in the PSSCH 408 starting from the first symbol containing the PSSCH DMRS. In Figure 4A the example shown, the first symbol containing the PSSCH DMRS is the fifth symbol that appears immediately after the last symbol carrying the PSCCH 406. Therefore, the SCI-2 412 is mapped to the RBs within the fifth symbol. In Figure 4BIn the example shown, the first symbol containing PSSCH DMRS is the second symbol, which also includes PSCCH 406. Additionally, SCI-2 / PSSCH DMRS 412 is shown to span symbols two to five. Thus, SCI-2 / PSSCH DMRS 412 can perform FDM with PSCCH 406 in symbols two to four and TDM with PSCCH 406 in symbol five.

[0096] SCI-2 can be scrambled separately from the sidelink shared channel. Additionally, SCI-2 can utilize QPSK. When PSSCH transmission spans two layers, the SCI-2 modulation symbols can be replicated (e.g., repeated) on the two layers. SCI-1 in PSCCH 406 can be blindly decoded at the receiving wireless communication device. However, since the format, starting position, and number of REs of SCI-2 412 can be derived from SCI-1, blind decoding of SCI-2 is not required at the receiver (receiving UE).

[0097] In Figure 4A and Figure 4B each of, the second symbol of each time slot 400a and 400b is replicated (repeated on) its first symbol 410 for automatic gain control (AGC) stabilization. For example, in Figure 4A the second symbol of PSCCH 406 that performs FDM with PSSCH 408b can be transmitted on both the first and second symbols. In Figure 4B the example shown, the second symbol of PSCCH 406 that performs FDM with SCI-2 / PSSCH DMRS 412 can be transmitted on both the first and second symbols.

[0098] Visual odometry can be used in sidelink (e.g., V2X) applications to estimate the trajectory and pose of a wireless communication device (e.g., a V2X device such as a vehicle). Pose refers to the translation of the vehicle (e.g., the geometric change of the vehicle's position in two or three dimensions) and the orientation / rotation of the vehicle (e.g., pitch, yaw, roll). Visual odometry involves comparing consecutive image frames (e.g., in a video sequence) to infer the vehicle's trajectory. For example, the two-dimensional displacement of five or more stationary key points detected and tracked across two camera images is sufficient to recover the three-dimensional displacement of the camera up to a global scale factor. In some examples, the vehicle can include an auxiliary sensor such as an inertial measurement unit (IMU) to determine the displacement at the global scale.

[0099] Figure 5FIG. is an illustration showing an example of an image 500 including key points 502. As used herein, the term key point 502 refers to a group of pixels 504 in the image 500 that can be tracked between image frames, such as corner points on an object. Figure 5 An example of the corner detection method shown is the features from the Features from Accelerated Segment Test (FAST) (Machine Learning for High-Speed Corner Detection, Edward Rosten & Tom Drummond, ECCV 2006: Computer Vision Vision-ECCV 2006, pp. 430-443, Part of the Lecture Notes in Computer Science book series (LNIP, Volume 3951)). In the FAST method, a tested pixel 504 with intensity Ip can be identified as an interest point. Then, a circle (e.g., a Bresenham circle with a radius of 3) of sixteen pixels (pixels 1 to 16) surrounding the tested pixel can be identified. If there is a set of n adjacent pixels in the circle of sixteen pixels that are all brighter than Ip + t or all darker than Ip - t, then the pixel p can be considered a corner point, where t is a threshold and n is configurable. In this example, n can be twelve. For example, the intensities of pixels 1, 5, 9, and 13 of the circle can be compared with Ip. If at least three of the four pixels do not meet the threshold criterion, then the pixel p is not considered an interest point. As is clear from Figure 5 it, at least three of the four pixels meet the threshold criterion. Therefore, all sixteen pixels can be compared with pixel p to determine whether twelve consecutive pixels meet the threshold criterion. This process can be repeated for each pixel 504 in the image 500 to identify the corner points corresponding to the key points 502 in the image 500.

[0100] Although Figure 5 the FAST key point identification method is illustrated, it should be understood that the present disclosure is applicable to any key point identification method. Examples of key point identification methods can include (but are not limited to) SIFT (Scale-Invariant Feature Transform), ORB (Oriented FAST (Features from Accelerated Segment Test) and Rotated BRIEF (Binary Robust Independent Elementary Features)), BRIEF, and Harris corners.

[0101] As indicated above, key point 502 represents a feature of image 500 that can be tracked. For example, various cross-correlation or optical flow methods can track features (key points) across image frames. In some examples, each feature may also include a feature descriptor that aids in the tracking process. The feature descriptor may summarize one or more characteristics of key point 502 in a vector format (e.g., of constant length). For example, the feature descriptor may correspond to the intensity of key point 502. Generally, the feature descriptor is independent of the key point 502 location, is robust to image transformations, and scales independently. Thus, key points with feature descriptors can be independently re-detected in each image frame and then subjected to a key point matching / tracking procedure. For example, key points in two different images with matching descriptors and the minimum distance between them can be considered matching key points.

[0102] Then, the pose of the camera can be calculated based on the two-dimensional displacements of multiple key points in consecutive images. For example, the pose can be determined by forming and factorizing the essential matrix using eight key points 502 or using the Nister method with five key points 502. As another example, the Perspective-n-Point (PnP) algorithm with three key points 502 can be used to determine the pose while additionally tracking the depth of the key points.

[0103] In some aspects, images captured by different cameras containing a minimum number of the same features (e.g., based on the pose determination method) can be used to determine the relative pose between the cameras. Figure 6 FIG. is an illustration showing an example of relative pose determination between vehicles 602 and 604 according to some aspects. In some examples, each of vehicles 602 and 604 can be a wireless communication device, such as a V2X device including a sensor (e.g., a camera) for capturing images. Additionally, vehicles 602 and 604 can each be a self-driving vehicle within an intelligent transportation system. Vehicles 602 and 604 are shown in a two-dimensional coordinate system represented by the X-axis and Y-axis. Thus, the pose of each of vehicles 602 and 604 can be determined in the X, Y coordinate system.

[0104] Furthermore, the relative pose between vehicles 602 and 604 can also be determined based on a rotational coordinate system centered on one of the vehicles (e.g., vehicle 602) represented by the X_v axis and Y_v axis. In some examples, the rotational coordinate system can be centered on the camera of vehicle 602. The relative pose of vehicle 604 with respect to vehicle 602 may include a relative translation 606 of vehicle 604 in the X_v and Y_v directions corresponding to ΔX v and ΔY v In addition, the relative pose of vehicle 604 with respect to vehicle 602 may include an angle ΔΘ corresponding to vehicle 604 vThe relative orientation 608.

[0105] To facilitate relative pose determination, various aspects of the present disclosure provide mechanisms for sharing visual features between wireless communication devices (e.g., vehicles 602 and 604). For example, vehicle 604 may capture an image within the field of view of an on-board camera of vehicle 604 and use FAST, ORB, BRIEF, SIFT, Harris corner, or another keypoint detection algorithm to identify multiple keypoints in the image. Vehicle 604 may then send the identified features (keypoints) to vehicle 602. Vehicle 602 may use the received keypoints from vehicle 604 and matching keypoints obtained from an image in the same or a similar (e.g., common) field of view captured by the on-board camera of vehicle 602 to perform relative pose determination between vehicle 602 and vehicle 604.

[0106] Figure 7 is a diagram illustrating exemplary signaling between wireless communication devices (WCD-1 702 and WCD-2 704) for relative pose determination. Each of WCD-1 702 and WCD-2 704 can be, for example, a vehicle (e.g., a self-driving vehicle), a UE, a V2X device, or a sidelink device. WCD-1 702 and WCD-2 704 are in the vicinity of each other. In some examples, WCD-1 702 and WCD-2 704 may have established a sidelink between them (e.g., via a discovery signal).

[0107] At 706, WCD-1 702 may send a request for visual feature sharing to WCD-2 704. For example, WCD-1 702 may not know its pose and may request that WCD-2 704 provide keypoints to WCD-1 702. In some examples, WCD-1 702 may send a request to provide keypoints for multiple images obtained by WCD-2 704 over time (e.g., at different instants). In some examples, the request may indicate a specific instant (e.g., t1, t2, ……, t N ) at which the image should be captured. In other examples, WCD-1 702 may send multiple requests at different instants, each request asking WCD-2 704 to provide keypoints from one or more images.

[0108] In some examples, the request may include an indication of the field of view (FOV) in which the key points are requested. For example, the FOV of the WCD-2704 may be adjustable, or the WCD-1 702 may send requests to multiple second WCDs, and the second WCD (e.g., WCD-2 704) having the requested FOV may respond to the request. In some examples, the indication may further include a coordinate system of the FOV. For example, the coordinate system may be a global coordinate system or other pre-configured coordinate system. Examples of global coordinate systems may include, but are not limited to, LLA (longitude, latitude, altitude) and ECEF (Earth-Centered, Earth-Fixed), also known as geocentric coordinate system. Thus, the request may request features within the FOV defined using a specific coordinate system. In other examples, the indication includes a differential value (e.g., + / -X degrees) of the FOV relative to a previous set of features (e.g., key points) received from the WCD-2704.

[0109] In some examples, the request may be sent via one or more of a unicast sidelink message, a multicast (or groupcast) sidelink message, or a broadcast sidelink message. In other examples, the request may be sent via a network entity (e.g., a base station or gNB in an aggregated base station architecture, or a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near RT) RAN intelligent controller (RIC), or a non-real-time (non RT) RIC in a decomposed base station architecture) that wirelessly communicates with the WCD-1 702 and the WCD-2 704. For example, the request may be sent to the network entity via a Uu link between the WCD-1 702 and the network entity, and the network entity may send the request to the WCD-2 704 via a Uu link between the network entity and the WCD-2 704.

[0110] At 708, the WCD-2 704 may obtain a plurality of first features of a first image captured by the WCD-2 704 in a first field of view. The first field of view may be indicated in the request, or may be based on the position of a sensor (e.g., a camera) on the WCD-2 704 that captured the image. The WCD-2 704 may use FAST, BRIEF, ORB, SIFT, Harris corner, or another key point detection algorithm to identify the plurality of first features in the first image. The WCD-2 704 may also determine (e.g., compute) a feature descriptor for each feature. In one example, the WCD-2 704 may obtain an image I using its camera at a first moment t1. The WCD-2 704 may then use a key point detection algorithm to determine that the M key point positions of the image I will be A = [(u1,v1),(u2,v2),…(u M ,v M )] and the corresponding features F = [F1,F2,…F M .

[0111] At 710, the WCD-2 704 may send a message to the WCD-1 702 that includes a plurality of first features. In some examples, each of the first features may include a corresponding first key point. In other examples, each of the first features may include a corresponding first key point and a corresponding first feature descriptor. The first feature descriptor may be a SIFT, ORB, HOG (Histogram of Oriented Gradients), GLOH (Gradient Location and Orientation Histogram), and / or SURF (Speeded Up Robust Features) feature descriptor. In one example, the message may include M features of the image {F} and the corresponding pixel locations {A} of each of these features. In some examples, the message may also include a timestamp indicating a first time (time t1) at which the plurality of first features were obtained.

[0112] In some examples, the message may be sent via one or more of a unicast sidelink message, a multicast (or groupcast) sidelink message, or a broadcast sidelink message. In other examples, the message may be sent via a network entity that wirelessly communicates with the WCD-1 702 and the WCD-2 704 (e.g., a base station or gNB in an aggregated base station architecture, or a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near RT) RAN intelligent controller (RIC), or a non-real-time (non RT) RIC in a disaggregated base station architecture). For example, the message may be sent to the network entity via a Uu link between the WCD-2 704 and the network entity, and the network entity may send the request to the WCD-1 702 via a Uu link between the network entity and the WCD-1 702.

[0113] At 712, the WCD-1 702 may obtain a plurality of second features of a second image captured by the WCD-1 702 in a second field of view. The second field of view and the first field of view may include a common field of view. The WCD-1 702 may use FAST, BRIEF, ORB, SIFT, Harris corner, or another key point detection algorithm to identify the plurality of second features in the second image. The WCD-1 702 may also determine (e.g., compute) a second feature descriptor for each feature. The second feature descriptor may be a SIFT, ORB, HOG, GLOH, and / or SURF feature descriptor.

[0114] In one example, the WCD-1 702 may use its camera to obtain an image L at a second time (e.g., a second moment t2). The second moment t2 may be temporally close to the first moment t1. For example, the second moment t2 may be within a preconfigured duration (or threshold duration) from the moment t1. In an example where the second moment t2 is outside the preconfigured duration (e.g., the time difference between t2 and t1 exceeds the threshold duration), the WCD-1 702 may not use the plurality of first features and may send a new request for visual feature sharing to the WCD-2 704, or the WCD-1 702 may use a subsequent set of features transmitted by the WCD-2 704 based on the original request sent at 706.

[0115] At 714, the WCD-1 702 may calculate the relative pose of the WCD-1 702 with respect to the WCD-2 704 based on the association between the plurality of first features and the plurality of second features. In one example, the WCD-1 702 may use the image L obtained from its camera at time t2, and match the plurality of first features F obtained from the WCD-2 704 with the plurality of second features obtained from the image L to associate the first features with the second features. For example, various cross-correlation or optical flow methods and / or feature descriptors may be used to match the first features and the second features. For example, the matched pixel positions of N features in L obtained by the WCD-1 702 may be represented as B = [(p_1,q_1),(p_2,q_2),…(p_N,q_N)]. The WCD-1 702 may then use the essential matrix, the Nister method, or the PnP algorithm to determine the relative pose.

[0116] Figure 8 is a diagram illustrating an example of relative pose determination using key points from images captured at different cameras C1 and C2 according to some aspects. In Figure 8 the example shown, each of the cameras C1 and C2 may be located on a different wireless communication device such as a vehicle. A real point M in the three-dimensional space (x,y,z) may be projected onto the respective image planes I1 and I2 of each of the vehicle cameras C1 and C2 of the vehicle to produce features (key points) m1 and m2. By correlating or associating (e.g., matching) multiple sets of features (e.g., corresponding to multiple real points), epipolar constraints on the relative vehicle pose (e.g., the line l1 between m1 and e1 and the line l2 between m2 and e2) may be extracted. Thus, based on the key points of multiple real points and the epipolar constraints, the first wireless communication device associated with the camera C1 may determine the relative pose (rotation (R), translation (T)) of the first wireless communication device with respect to the second wireless communication device associated with the camera C2.

[0117] In some examples, a minimum number (e.g., between three and eight) of correctly matched features can be used to determine the relative pose. However, typically dozens of corresponding matched points may be required to filter outliers, such as using Random Sample Consensus (RANSAC). In practice, to obtain sufficient matched features to determine the relative pose, thousands of visual features (e.g., between 8,000 and 15,000 visual features) may need to be shared between vehicles. Sending such a large number of visual features incurs communication overhead and may limit the possibility of including visual features as part of a Basic Safety Message (BSM) in a V2X system.

[0118] In addition, in an environment with minimal texture (e.g., minimal variation in the scene) that does not contain many different objects, the pixel gradients in the images obtained in such environments may not be obvious. Thus, it may be different for the ego vehicle to obtain sufficient visual features (e.g., key points) to share with the target vehicle. This may limit the ability to obtain the relative pose in such environments.

[0119] Figure 9 FIG. is an illustration of an example of a low texture environment 900 including an ego vehicle 902 and a target vehicle 904 in accordance with some aspects. As Figure 9 shown in the example of, in most expected travel scenarios, lane markings 906a, 906b, 906c, 906d, and 906e may be present on the road. The lane markings 906a to 906e may have different colors (e.g., white or yellow) and may be of different types (e.g., double solid lines, single solid lines, or dashed lines (broken lines)). In some examples, in such a low texture environment 900, key points can be selected from the corner points 908 of the lane markings. For example, due to its higher gradient, the corner points of a broken line lane marking (e.g., lane marking 906c) can be used.

[0120] Various aspects relate to using lane markings (e.g., lane markings 906a to 906e) in combination with key points (e.g., corner points 908) to obtain the relative pose between vehicles (e.g., vehicles 902 and 904). In some examples, by using lane markings, the ego vehicle 902 can send a reduced number of visual features, which can reduce the communication overhead required to send visual features to the target vehicle 904. In addition, in a low texture environment, as Figure 9 shown, using only a few visual features (key points) along with lane markings 906a to 906c can enable the target vehicle 904 to obtain the relative pose.

[0121] In some examples, a self vehicle (e.g., a transmitting wireless communication device) may send lane features identifying lane markings and a plurality of first features (e.g., first key points) to a target vehicle (e.g., a receiving wireless communication device). In some examples, the plurality of first features provided by the transmitting wireless communication device may include a subset of a larger set of first features obtained by the transmitting wireless communication device in order to reduce overhead. In other examples, the plurality of first features includes all or most of the visual features obtained in a low-texture environment. To utilize lane markings and visual features to determine relative pose, the transmitting wireless communication device may also send a two-line two-point (2L2P) metric to the receiving wireless communication device.

[0122] Figure 10 is a diagram illustrating an example of a 2L2P invariant according to some aspects. The 2L2P invariant is a projective geometric invariant that defines four coplanar features (e.g., two lines and two points) that remain invariant under projective transformation. Here, the two lines may correspond to two lane markings, and the two points may correspond to two key points. In Figure 9 the example shown, let L1 and L2 be the two lines, and let p1 and p2 be the two points. Then, the 2L2P metric can be defined as:

[0123]

[0124] The above 2L2P metric (shown in Equation 1) defines the ratio of the distance ratios of point p i to line L k . If 2L2P(L1,L2,p1,p2) = α, then all points q such that 2L2P(L1,L2,p1,q) = α lie on the line N1 to p2. Additionally, if 2L2P(L3,L2,p1,p2) = β, then all points q such that 2L2P(L3,L2,p1,q) = β lie on the line N2 to p2. Thus, x = p2 is uniquely determined by 2L2P(L1,L2,p1,x) = α and 2L2P(L3,L2,p1,x) = β. In other words, {L1,L2,L3,p1} forms a basis for defining the point {p k}, k≠1, in such a way that by defining the 2L2P pairs {α k ,β k}.

[0125] Generally speaking, 2L2P(L i ,L j ,p m ,p n ) represents providing the points p m ,p n relative to the lines L i ,L jA scalar of invariant measure. In addition, 2L2P(L i ,L j ,L k ,p m ,p n ) represents the tuple (α,β), where α represents the point p m ,p n relative to the line L i ,L j of invariant measure, and β represents the point p m ,p n relative to the line L i ,L k of invariant measure.

[0126] Figure 11 is a diagram illustrating an example of determining a relative pose using lane markings according to some aspects. In Figure 11 the example shown, a transmitting wireless communication device (WCD-1) 1102 (e.g., a self-vehicle) communicates with a receiving wireless communication device (WCD-2) 1104 (e.g., a target vehicle). Each of the WCD-1 1102 and WCD-2 1104 can be, for example, a vehicle, a UE, a V2X device, or a sidelink device. The WCD-1 1102 and WCD-2 1104 are near each other. In some examples, the WCD-1 1102 and WCD-2 1104 may have established a sidelink between them (e.g., via a discovery signal).

[0127] At 1106, the WCD-1 1102 can send a message to the WCD-2 1104 that includes a plurality of first features, lane features, and 2L2P metrics in the first field of view of the WCD-1 1102. In some examples, the WCD-1 1102 can send the plurality of first features, lane features, and 2L2P metrics in response to a request for visual feature sharing, as Figure 7 shown. In some examples, each of the first features may include a corresponding first key point of a first image captured by the WCD-1 1102. In other examples, each of the first features may include a corresponding first key point and a corresponding first feature descriptor. The first feature descriptor can be a SIFT, ORB, HOG (Histogram of Oriented Gradients), GLOH (Gradient Location and Orientation Histogram), and / or SURF (Speeded Up Robust Features) feature descriptor. In some examples, the plurality of first features may include, for example, a subset of a larger set of first features obtained by the WCD-1 1102 to reduce communication overhead.

[0128] In one example, the message may include the key points {p}, the corresponding descriptors for the key points {p}, and 2L2P(L i,L j ,p m ,p n ) A metric that is for a random or ordered set of key points The metric L with respect to a lane marking (e.g., a line) i ,L j . Here,[[]]END]] In some examples,[[]]END]] can be selected such that they represent the corners of a broken lane that are not considered part of the 2L2P metric (e.g.,[[]]END]] Figure 9 the corner 908 shown). For example, if L[[]]END]] i ,L[[]]END]] j is the line considered in the 2L2P metric (e.g., as in 2L2P(L[[]]END]] i ,L[[]]END]] j ,p[[]]END]] m ,p[[]]END]] n ), then the key point p[[]]END]] m ,p[[]]END]] n is selected from the corner of another lane marking L[[]]END]] k (k≠i,j) or is selected from multiple other lane markings. As indicated above, the corners of broken lane markings can have a higher gradient, and thus using the corners of broken lane markings increases the likelihood (enhances the likelihood) of obtaining the correct corresponding key points (e.g., achieving a match) in the view of the WCD-2. In other examples,[[]]END]] can be constrained to be located in the space between a pair of lane markings (e.g., L[[]]END]] i ,L[[]]END]] j or L[[]]END]] i ,L[[]]END]] k ). This constraint can be further included in the message. For example, the message can further indicate[[]]END]] the pair of lane markings between which it can be located. In some examples, the pair of lane markings includes at least one of the lane markings L[[]]END]] i ,L[[]]END]] j used in the 2L2P metric.[[]]END]]

[0129] The lane feature can identify at least two lane markings used in the 2L2P metric transmitted to the WCD-2 1104. For example, the lane feature can include the corresponding color (e.g., yellow or white) of each lane marking used in the 2L2P metric, the corresponding type of lane marking (e.g., double solid line, single solid line, dashed / broken line) of each lane marking used in the 2L2P metric, and / or the order in which the lane markings can be viewed using a preconfigured rule (e.g., from left to right or from right to left).[[]]END]]

[0130] In some examples, the message may be sent via one or more of a unicast sidelink message, a multicast (or groupcast) sidelink message, or a broadcast sidelink message. In other examples, the message may be sent via a network entity that wirelessly communicates with WCD-1 1102 and WCD-2 1104 (e.g., a base station or gNB in an aggregated base station architecture, or a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near RT) RAN intelligent controller (RIC), or a non-real-time (non RT) RIC in a disaggregated base station architecture). For example, the message may be sent to the network entity via a Uu link between WCD-1 1102 and the network entity, and the network entity may send the request to WCD-2 1104 via a Uu link between the network entity and WCD-2 1104).

[0131] At 1108, WCD-2 1104 may obtain a plurality of second features in a second field of view associated with a first wireless communication device. Each second feature of the second features may include a respective second key point of a second image captured by WCD-2. In other examples, each second feature of the second features may include a respective second key point and a corresponding second feature descriptor. WCD-2 1104 may use FAST, BRIEF, ORB, SIFT, Harris corner, or another key point detection algorithm to identify the plurality of second features in the second image. WCD-2 1104 may also determine (e.g., compute) a second feature descriptor for each feature. The second feature descriptor may be a SIFT, ORB, HOG, GLOH, and / or SURF feature descriptor.

[0132] At 1110, WCD-2 1104 may associate the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to respective first key points within the plurality of first features. For example, WCD-21104 may obtain the set of corresponding key points {q} by matching the plurality of second features {s} with the plurality of first features {p}, using, for example, the descriptors of {p}.

[0133] At 1112, WCD-2 1104 may identify matching key points within the set of corresponding key points that satisfy a respective 2L2P metric. For example, for those corresponding points {q m ,q m} ∈ q, WCD-2 1104 checks whether the 2L2P (L i ,L j ,q m ,q n ) metric is satisfied. As an example, the initial 2L2P (L i ,L j ,pm , p n ) metric (for key point {p m , p n ) can be a specific value (e.g., 0.5). WCD-2 1104 can calculate a new 2L2P (L i , L j , q m , q n )(for the corresponding set of key points obtained by WCD-2 1104 (e.g., {q m , q n}) corresponding to {p m , p n}) and compare the initial 2L2P metric with the new 2L2P metric. If the new 2L2P metric is within a threshold amount from the initial 2L2P metric (e.g., 0.05), then WCD-2 1104 can consider that the 2L2P metric for the key point {q m , q m}) is satisfied. Assume represents the matching key points that satisfy the corresponding 2L2P metric. In this example, {r} represents the matching key points within the set of corresponding key points, and these matching key points are most likely to be true matches since the additional 2L2P constraints have been satisfied.

[0134] At 1114, WCD-2 1104 determines whether the number of matching key points (e.g., the number of key points within {r}) is below a threshold. In some examples, the threshold can be three, five, eight, or other suitable numbers. Assume the threshold is five. If |{r}| ≥ 5, then it is determined that the minimum number of key points required for determining the relative pose has been satisfied. Thus, at 1116, WCD-2 1104 can calculate the relative pose of WCD-2 1104 with respect to WCD-1 1102 based on the matching key points.

[0135] However, if |{r}| < 5, then at 1118, WCD-2 1104 can send a request to WCD-1 1102 for additional 2L2P metrics. For example, WCD-2 1104 can request the corresponding additional 2L2P metrics associated with additional first key point pairs outside the set of first key point pairs initially used by WCD-1 to provide the initial 2L2P metric. Thus, WCD-2 1104 can request WCD-1 1102 to provide additional 2L2P metrics for additional first key point pairs for which WCD-2 1104 does not have corresponding 2L2P metrics. In some examples, the request includes a preferred key point among the matching key points, and WCD-1 1102 should use this preferred key point for the additional 2L2P metric. For example, the request may include the matching key point p t, the matching key point corresponds to q in the coordinate system of WCD-2 1104 t , where q t ∈{r}. For example, preferably the key point q t can correspond to one of the matching key points that have satisfied the 2L2P metric, and thus can provide a good basis for the additional 2L2P metric. Therefore, preferably the key point can be included in each of the additional first key point pairs for the corresponding additional 2L2P metric. In other examples, the request can include additional first key point pairs for which the corresponding additional 2L2P metric is requested.

[0136] At 1120, WCD-1 1102 can send the corresponding additional 2L2P metric requested by WCD-2 1104. In some examples, WCD-1 1102 can use the preferred key point, the two initial lane markings, and the additional lane marking as the basis for the additional 2L2P metric. For example, WCD-1 1102 can provide the 2L2P(L i ,L j ,L k ,p t ,p n ) metric to some other first key points {f}, where p n ∈{f}, by considering 2L2P(L i ,L j ,L k ,p t ) as the basis. In this case, WCD-1 1102 only provides the 2L2P(L i ,L j ,L k ,p t ,p n ) metric and does not need to provide the feature descriptors of {f}, because WCD-2 1104 can deterministically identify the corresponding key point {g} that corresponds to (corresponds to) {f} (from 2L2P(L i ,L j ,L k ,p t ,p n ) metric). Therefore, WCD-2 1104 can identify the additional matching points that satisfy the additional 2L2P metric without receiving an indication of the corresponding other first key points.

[0137] In other examples, the WCD-2 1104 may not provide the preferred key points in the request. In this example, the WCD-1 1102 may identify additional first key point pairs including other first key points excluded from the plurality of first features initially provided by the WCD-1 1102. For example, the other first key points may be within the larger set of first key points obtained by the WCD-1 1102, but are not provided to the WCD-2 1104 in the message sent at 1106. In this example, the WCD-1 1102 may provide additional 2L2P metrics, as well as an indication of each of the other first key points and the corresponding key point descriptors associated therewith.

[0138] In other examples where the request includes additional first key point pairs requested by the WCD-2 1104, the WCD-1 1102 may provide only the additional 2L2P metrics for the requested additional first key point pairs. Here, the WCD-1 1102 may not provide the feature descriptors associated with the additional first key point pairs.

[0139] At 1112, the WCD-2 1104 may again identify additional matching key points that satisfy the additional corresponding 2L2P metrics from the additional 2L2P metrics. For example, for each 2L2P (L i ,L j ,L k ,p t ,p n ) = (α,β) transmitted by the WCD-1 1102, the WCD-2 1104 may deterministically obtain the corresponding (matching) key point, g n by way of solving 2L2P (L i ,L j ,L k ,q t ,x) = α and 2L2P (L i ,L j ,L k ,q t ,x) = β. Solving for x gives the intersection point x = g n . That is, the key point g n is uniquely obtained by the intersection of the lines obtained by the signaled metrics 2L2P (L i ,L j ,L k ,q t ,x) = α and 2L2P (L i ,L j ,L k ,q t ,x) = β. Here, again, q t ,p tThey are the corresponding key points (and base points) in the fields of view of WCD-2 1104 and WCD-1 1102 respectively.

[0140] Figure 12 is a block diagram illustrating an example of a hardware implementation of a wireless communication device 1200 employing a processing system 1214. For example, the wireless communication device 1200 may correspond to a sidelink device such as a vehicle or other V2X device as shown and described above with reference to Figure 1 , Figure 3 , Figure 6 , Figure 7 and / or Figure 9 shown and described.

[0141] The wireless communication device 1200 may be implemented using a processing system 1214 that includes one or more processors 1204. Examples of processors 1204 include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic components, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. In various examples, the wireless communication device 1200 may be configured to perform any one or more of the functions described herein. That is, the processor 1204 as utilized in the wireless communication device 1200 may be used to implement any one or more of the processes and procedures described below.

[0142] In some cases, the processor 1204 may be implemented via a baseband or modem chip, and in other implementations, the processor 1204 may include several devices distinct from and different from the baseband or modem chip (e.g., in scenarios such as those that may work together to implement the examples discussed herein). And as mentioned above, various hardware arrangements and components outside of the baseband modem processor may be used in implementations, including RF chains, power amplifiers, modulators, buffers, interleavers, adders / summers, etc.

[0143] In this example, the processing system 1214 may be implemented using a bus architecture, which is generally represented by bus 1202. The bus 1202 may include any number of interconnecting buses and bridges, depending on the specific application of the processing system 1214 and the overall design constraints. The bus 1202 links together various circuits including one or more processors (generally represented by processor 1204), a memory 1205, and a computer-readable medium (generally represented by computer-readable medium 1206). The bus 1202 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein.

[0144] The bus interface 1208 provides an interface between the bus 1202 and the transceiver 1210. The transceiver 1210 provides a communication interface or component for communicating with various other devices via a transmission medium (e.g., an air interface). Depending on the nature of the device, a user interface 1212 (e.g., a keypad, a display, a touch screen, a speaker, a microphone, a control knob, etc.) may also be provided. Of course, such a user interface 1212 is optional and may be omitted in some examples. In addition, the bus interface 1208 may also provide an interface between the bus 1202 and a sensor 1230 such as a camera.

[0145] The processor 1204 is responsible for managing the bus 1202 and general processing, including executing software stored on the computer-readable medium 1206. When executed by the processor 1204, the software causes the processing system 1214 to perform the various functions described below for any particular device. The computer-readable medium 1206 and the memory 1205 may also be used to store data manipulated by the processor 1204 when executing the software. For example, the memory 1205 may store one or more of visual features 1216 (e.g., key points and associated key point descriptors), 2L2P metrics 1218, lane features 1220, one or more relative poses 1222, and / or requests 1224 for additional 2L2P metrics / visual features, which may be used by the processor 1204 in a visual feature sharing application.

[0146] One or more processors 1204 in the processing system may execute software. Software should be interpreted broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on the computer-readable medium 1206.

[0147] The computer-readable medium 1206 can be a non-transitory computer-readable medium. Non-transitory computer-readable media include, for example, magnetic storage devices (such as hard disks, floppy disks, magnetic strips), optical disks (such as compact discs (CDs) or digital versatile discs (DVDs)), smart cards, flash memory devices (such as cards, sticks, or key drives), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, removable disks, and any other suitable medium for storing software and / or instructions that can be accessed and read by a computer. The computer-readable medium 1206 can reside within the processing system 1214, be located external to the processing system 1214, or be distributed across multiple entities including the processing system 1214. The computer-readable medium 1206 can be embodied as a computer program product. For example, the computer program product can include the computer-readable medium in a packaging material. In some examples, the computer-readable medium 1206 can be a part of the memory 1205. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure, depending on the particular application and the overall design constraints imposed on the overall system. In some examples, the computer-readable medium 1206 can be implemented on a manufactured article, which can also include one or more other elements or circuits, such as the processor 1204 and / or the memory 1205.

[0148] In some aspects of the present disclosure, the processor 1204 can include circuitry configured for various functions. For example, the processor 1204 can include communication and processing circuitry 1242 configured to communicate with one or more sidelink devices (such as other wireless communication devices) via a respective sidelink (such as the PC5 interface). Additionally, the communication and processing circuitry 1242 can be configured to communicate with a network entity (such as a base station, such as a gNB or an eNB) via the Uu link. In some examples, the communication and processing circuitry 1242 can include one or more hardware components that provide a physical structure that performs processes related to wireless communication (such as signal reception and / or signal transmission) and signal processing (such as processing received signals and / or processing signals for transmission). For example, the communication and processing circuitry 1242 can include one or more transmit / receive chains.

[0149] In some specific implementations where communication involves receiving information, the communication and processing circuitry 1242 may obtain information from components of the wireless communication device 1200 (e.g., from the transceiver 1210 that receives information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium), process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry 1242 may output the information to another component of the processor 1204, to the memory 1205, or to the bus interface 1208. In some examples, the communication and processing circuitry 1242 may receive one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 1242 may receive information via one or more channels. In some examples, the communication and processing circuitry 1242 may include functionality for components used for receiving. In some examples, the communication and processing circuitry 1242 may include functionality for components used for processing, which includes components for demodulation, components for decoding, etc.

[0150] In some specific implementations where communication involves transmitting (e.g., sending) information, the communication and processing circuitry 1242 may obtain information (e.g., from another component of the processor 1204, the memory 1205, or the bus interface 1208), process (e.g., modulate, encode, etc.) the information, and output the processed information. For example, the communication and processing circuitry 1242 may output the information to the transceiver 1210 (e.g., the transceiver that sends information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium). In some examples, the communication and processing circuitry 1242 may transmit one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 1242 may transmit information via one or more channels. In some examples, the communication and processing circuitry 1242 may include functionality for components used for transmitting (e.g., components for sending). In some examples, the communication and processing circuitry 1242 may include functionality for components used for generating, which includes components for modulation, components for encoding, etc.

[0151] In an example where the wireless communication device 1200 is a target (or receiving) wireless communication device (e.g., a target vehicle), the communication and processing circuitry 1242 may be configured to receive, via the transceiver 1210, lane features 1220 that identify two (or more) lane markings from another wireless communication device (e.g., a second wireless communication device). In some examples, the lane features 1220 may include one or more of the following: lane marking color, type of lane marking, or the order in which lane markings are viewed based on rules. The communication and processing circuitry 1242 may be further configured to store the lane features 1220 in, for example, the memory 1205.

[0152] In addition, the communication and processing circuitry 1242 may be configured to receive, via the transceiver 1210, a plurality of first features (e.g., visual features 1216) in a first field of view associated with a second wireless communication device. Here, each of the plurality of first features may include a respective first key point of a first image captured by the second wireless communication device. In some examples, each of the plurality of first features further includes a respective first feature descriptor corresponding to the respective first key point. The communication and processing circuitry 1242 may be further configured to store the received plurality of first features 1216, e.g., in the memory 1205, for further processing.

[0153] The communication and processing circuitry 1242 may be further configured to receive, via the transceiver 1210, from the second wireless communication device, a respective two lines two points (2L2P) metric 1218 for each first key point pair within a set of first key point pairs based on two lane markings. In some examples, the set of first key point pairs includes corner features of at least one additional lane marking excluded from the two lane markings. For example, the at least one additional lane marking may include a broken lane marking. In some examples, the set of first key point pairs may be located in a space between a pair of lane markings. In this example, the communication and processing circuitry 1242 may be further configured to receive an indication of the pair of lane markings from the second wireless communication device. In some examples, the pair of lane markings may include at least one of the two lane markings. The communication and processing circuitry 1242 may be further configured to store the 2L2P metric 1218, e.g., in the memory 1205.

[0154] In an example where the wireless communication device 1200 is a transmitting wireless communication device (e.g., a self - vehicle), the communication and processing circuitry 1242 may be configured to transmit, via the transceiver 1210, lane features 1220 identifying two (or more) lane markings to at least one other wireless communication device. In addition, the communication and processing circuitry 1242 may be configured to transmit, via the transceiver 1210, a plurality of features 1216 in a field of view associated with the wireless communication device 1200. Each of the plurality of features may include a respective key point of an image captured by the wireless communication device 1200. The communication and processing circuitry 1242 may be further configured to transmit, via the transceiver 1210, a respective two lines two points (2L2P) metric 1218 for each key point pair within a set of key point pairs for the plurality of features 1216 based on two lane markings.

[0155] In some examples, each of the plurality of features 1216 also includes a corresponding feature descriptor corresponding to a respective key point. In some examples, the lane feature 1220 includes one or more of the following: lane marking color, type of lane marking, or order of viewing lane markings based on rules. In some examples, the plurality of features 1216 includes corner features of at least one additional lane marking excluded from two lane markings. For example, the at least one additional lane marking can be a broken-line lane marking. In some examples, the plurality of features is located in a space between a pair of lane markings. In this example, the communication and processing circuitry 1242 can be further configured to send an indication of the pair of lane markings to at least one other wireless communication device. In some examples, the pair of lane markings can include at least one of the two lane markings. The communication and processing circuitry 1242 can be further configured to execute communication and processing instructions (software) 1252 stored in the computer-readable medium 1206 to implement one or more of the functions described herein.

[0156] The processor 1204 can also include a visual feature sharing circuit 1244 configured for visual feature sharing between the wireless communication device 1200 and at least one other wireless communication device. In an example where the wireless communication device 1200 is a receiving (target) wireless communication device, the visual feature sharing circuit 1244 can be configured to control the sensor 1230 to capture a second image in a second field of view of the wireless communication device 1200 and process the second image to extract (obtain) a plurality of second features. Here, each of the plurality of second features can include a respective second key point of the second image captured by the sensor 1230. The visual feature sharing circuit 1244 can be further configured to receive the lane feature 1220, the plurality of first features 1216, and the 2L2P metric 1218 from the second wireless communication device via the communication and processing circuitry 1242 and the transceiver 1210.

[0157] The visual feature sharing circuit 1244 can be further configured to send a request 1224 for a respective additional 2L2P metric associated with an additional first key point pair outside the set of first key point pairs to the second wireless communication device via the communication and processing circuitry 1242 and the transceiver 1210. In addition, the visual feature sharing circuit 1244 can be configured to receive the respective additional 2L2P metric from the second wireless communication device via the communication and processing circuitry 1242 and the transceiver 1210.

[0158] In an example where the wireless communication device is a transmitting wireless communication device, the visual feature sharing circuit 1244 may be configured to generate lane features 1220, a plurality of features 1216, and 2L2P metrics 1218, and transmit them to at least one other wireless communication device via the communication and processing circuit 1242 and the transceiver 1210. For example, the visual feature sharing circuit 1244 may be configured to control the sensor 1230 to capture an image and generate (obtain / extract) a plurality of features 1216 from the image. The visual feature sharing circuit 1244 may be further configured to identify lane features 1220 based on the image or other sensor data (e.g., other images or data). The visual feature sharing circuit 1244 may be further configured to select key point pairs and calculate corresponding 2L2P metrics 1218 for each key point pair.

[0159] The visual feature sharing circuit 1244 may be further configured to receive, via the communication and processing circuit 1242 and the transceiver 1210, a request from at least one other wireless communication device for corresponding additional 2L2P metrics 1218 associated with additional key point pairs outside the set of key point pairs. In some examples, the request includes a preferred key point in each additional first key point included in the additional first key point pair for the corresponding additional 2L2P metric. In some examples, the visual feature sharing circuit 1244 may be configured to use the preferred key point, two lane markings, and additional lane markings as a basis for the additional 2L2P metric. In some examples, each additional key point pair in the additional key point pairs includes a preferred key point and a corresponding other key point within a subset of the plurality of features. In some examples, the request includes the additional key point pairs for which the corresponding 2L2P metrics are requested.

[0160] In addition, the visual feature sharing circuit 1244 may be configured to transmit the corresponding additional 2L2P metrics to at least one other wireless communication device via the communication and processing circuit 1242 and the transceiver 1210. In some examples, each additional key point pair in the additional key point pairs includes other key points excluded from the plurality of features. In this example, the visual feature sharing circuit 1244 may be configured to transmit the additional 2L2P metrics 1218 and an indication for each of the other key points, the indication including a corresponding key point descriptor associated therewith. The visual feature sharing circuit 1244 may be further configured to execute visual feature sharing instructions (software) 1254 stored in the computer-readable medium 1206 to implement one or more of the functions described herein.

[0161] In an example where the wireless communication device 1200 is a receiving (target) wireless communication device, the processor 1204 may further include a pose calculation circuit 1246 configured to calculate a relative pose between the wireless communication device 1200 and a second wireless communication device (e.g., relative pose 1222). In some examples, the pose calculation circuit 1246 may be configured to associate a plurality of first features 1216 with a plurality of second features 1216 to obtain a set of corresponding key points within the plurality of second features corresponding to respective first key points within the plurality of first features. In some examples, each first feature among the plurality of first features 1216 further includes a respective first feature descriptor corresponding to the respective first key point, and each second feature among the plurality of second features 1216 further includes a respective second feature descriptor corresponding to the respective second key point. In this example, the pose calculation circuit 1246 may be configured to associate the plurality of first features with the plurality of second features based on the first key points, the second key points, the first feature descriptors, and the second feature descriptors.

[0162] In addition, the pose calculation circuit 1246 may be further configured to identify matching key points within the set of corresponding key points that satisfy a respective 2L2P metric 1218. The pose calculation circuit 1246 may then be configured to calculate a relative pose of the wireless communication device 1200 relative to the second wireless communication device based on the matching key points.

[0163] The pose calculation circuit 1246 may be further configured to determine a number of the matching key points and compare the number of the matching key points with a threshold. In response to the number of the matching key points being less than the threshold, the pose calculation circuit 1246 may be configured to operate with the visual feature sharing circuit 1244 to send a request 1224 for additional 2L2P metrics 1218 to the second wireless communication device. In some examples, the request includes a preferred key point in each additional first key point pair of the matching key points to be included in the additional first key point pairs for the respective additional 2L2P metrics. In some examples, the respective additional 2L2P metrics 1218 use the preferred key points, two lane markings, and additional lane markings as a basis. In some examples, the request 1224 includes additional key point pairs for which the respective 2L2P metrics 1218 are requested. In some examples, each first additional key point pair among the additional first key point pairs includes other key points excluded from the plurality of first features. In this example, the visual feature sharing circuit 1244 may receive the additional 2L2P metrics and an indication of each of the other first key points and the respective key point descriptors associated therewith.

[0164] Upon receiving additional 2L2P metrics, the pose calculation circuit 1246 may be further configured to identify additional matching key points that satisfy the additional respective 2L2P metrics to calculate a relative pose. In some examples, each additional first key point pair in the additional first key point pairs includes a preferred key point and a respective other key point within a subset of the plurality of first features 1216. In this example, the pose calculation circuit 1246 may be configured to identify additional matching points that satisfy the additional 2L2P metrics without receiving an indication of the respective other first key points from the second wireless communication device. The pose calculation circuit 1246 may also be configured to execute pose calculation instructions (software) 1256 stored in the computer-readable medium 1206 to implement one or more of the functions described herein.

[0165] Figure 13 is a flowchart 1300 of an exemplary process for relative pose determination using lane markings according to some aspects. As described below, in certain specific implementations within the scope of the present disclosure, some or all of the illustrated features may be omitted, and some of the illustrated features may not be required for all implementations of the examples. In some examples, the method may be performed by the wireless communication device 1200 as described and Figure 12 illustrated above, by a processor or processing system, or by any suitable component for performing the described functions.

[0166] At block 1302, a wireless communication device (e.g., a first wireless communication device) may receive lane features identifying two lane markings from a second wireless communication device. In some examples, the lane features may include one or more of the following: lane marking color, type of lane marking, or the order in which the lane markings are viewed based on rules. For example, as described above in connection with Figure 12 the illustrated and described communication and processing circuit 1242 in conjunction with the visual feature sharing circuit 1244 and the transceiver 1210 may provide components for receiving the lane features.

[0167] At block 1304, the first wireless communication device may receive a plurality of first features in a first field of view associated with the second wireless communication device, where each first feature in the plurality of first features includes a respective first key point of a first image captured by the second wireless communication device. As described above in connection with Figure 12 the illustrated and described communication and processing circuit 1242 in conjunction with the visual feature sharing circuit 1244 and the transceiver 1210 may provide components for receiving the plurality of first features.

[0168] At block 1306, the first wireless communication device may receive from the second wireless communication device a respective two - lines - two - points (2L2P) metric for each first key point pair within a set of first key point pairs for a plurality of first features based on two lane markings. In some examples, the set of first key point pairs includes corner features of at least one additional lane marking excluded from the two lane markings. For example, the at least one additional lane marking may include a broken - line lane marking. In some examples, the set of first key point pairs is located in the space between a pair of lane markings. In this example, the first wireless communication device may further receive from the second wireless communication device an indication of the pair of lane markings. In some examples, the pair of lane markings includes at least one of the two lane markings. For example, as described above in connection with Figure 12 the communication and processing circuit 1242 shown and described, together with the visual feature sharing circuit 1244 and the transceiver 1210, may provide components for receiving the 2L2P metric.

[0169] At block 1308, the first wireless communication device may obtain a plurality of second features in a second field of view associated with the first wireless communication device, where each second feature of the plurality of second features includes a respective second key point of a second image captured by the first wireless communication device. For example, as described above in connection with Figure 12 the pose calculation circuit 1246 shown and described, together with the sensor 1230, may provide components for obtaining the plurality of second features.

[0170] At block 1310, the first wireless communication device may associate the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to respective first key points within the plurality of first features. In some examples, each first feature of the plurality of first features further includes a respective first feature descriptor corresponding to the respective first key point, and each second feature of the plurality of second features further includes a respective second feature descriptor corresponding to the respective second key point. In this example, the first wireless communication device may associate the plurality of first features with the plurality of second features based on the first key points, second key points, first feature descriptors, and second feature descriptors. For example, as described above in connection with Figure 12 the pose calculation circuit 1246 shown and described may provide components for associating the first features and the second features to obtain the set of corresponding key points.

[0171] At block 1312, the first wireless communication device may identify matching key points within the set of corresponding key points that satisfy the respective 2L2P metrics. For example, as described above in connection with Figure 12 the pose calculation circuit 1246 shown and described may provide components for identifying the matching key points.

[0172] At block 1314, the first wireless communication device may calculate a relative pose of the first wireless communication device with respect to the second wireless communication device based on matching key points. For example, the pose calculation circuit 1246 shown and described above in Figure 12 may provide components for calculating the relative pose.

[0173] Figure 14 is a flowchart of another exemplary process 1400 for relative pose determination using lane markings according to some aspects. As described below, in certain specific implementations within the scope of the present disclosure, some or all of the illustrated features may be omitted, and some of the illustrated features may not be required for all specific implementations of the examples. In some examples, the method may be performed by the wireless communication device 1200 as shown and described above, by a processor or processing system, or by any suitable component for performing the described functions. Figure 12 As illustrated.

[0174] At block 1402, a wireless communication device (e.g., the first wireless communication device) may determine whether the number of matching key points (e.g., as identified at block 1312 as shown in Figure 13 ) is greater than or equal to a threshold. In some examples, the threshold may be three, five, eight, or some other suitable number of matching key points required to calculate the relative pose. For example, the pose calculation circuit 1246 shown and described above in Figure 12 may provide components for determining whether the number of matching key points is greater than or equal to the threshold.

[0175] If the number of matching key points is greater than or equal to the threshold (Y branch of block 1402), then at block 1404, the first wireless communication device may calculate a relative pose of the first wireless communication device with respect to the second wireless communication device based on the matching key points. For example, the pose calculation circuit 1246 shown and described above in Figure 12 may provide components for calculating the relative pose.

[0176] If the number of matching key points is less than the threshold (N branch of block 1402), then at block 1406, the first wireless communication device may send a request for corresponding additional 2L2P metrics associated with additional first key point pairs outside of the set of first key point pairs. In some examples, the request includes a preferred key point among the matching key points, and the preferred key point is included in each of the additional first key point pairs for the corresponding additional 2L2P metrics. In some examples, the request includes the additional first key point pairs for which the corresponding additional 2L2P metrics are requested. As described above in Figure 12The pose calculation circuit 1246 shown and described, together with the visual feature sharing circuit 1244, the communication and processing circuit 1242, and the transceiver 1210, can provide components for sending requests for corresponding additional 2L2P metrics.

[0177] At block 1408, the first wireless communication device may receive the corresponding additional 2L2P metrics from the second wireless communication device. In some examples, the corresponding additional 2L2P metrics are based on preferred key points, two lane markings, and additional lane markings. In some examples, each first additional key point pair in the additional first key point pairs includes other key points excluded from the plurality of first features. In this example, the first wireless communication device may receive the additional 2L2P metrics and an indication of each first key point in the other first key points and its corresponding key point descriptor associated therewith. For example, as described above in connection with Figure 12 The pose calculation circuit 1246 shown and described, together with the visual feature sharing circuit 1244, the communication and processing circuit 1242, and the transceiver 1210, can provide components for receiving the corresponding additional 2L2P metrics.

[0178] At block 1410, the first wireless communication device may identify additional matching key points that satisfy the additional corresponding 2L2P metrics. In some examples, each additional first key point pair in the additional first key point pairs includes a preferred key point and a corresponding other first key point within a subset of the plurality of first features. In this example, the first wireless communication device may identify the additional matching points that satisfy the additional 2L2P metrics without receiving an indication of the corresponding other first key points from the second wireless communication device. For example, as described above in connection with Figure 12 The pose calculation circuit 1246 shown and described can provide components for identifying additional matching key points.

[0179] The process then returns to block 1402, where the first wireless communication device determines whether the number of matching key points (including the additional matching key points) is greater than or equal to a threshold. If so (the Y branch of block 1402), then at block 1404, the first wireless communication device calculates its relative pose. If not (the N branch of block 1402), then the first wireless communication sends another request for the additional 2L2P metrics. This process may be repeated until at least a threshold number of matching key points are identified.

[0180] In one configuration, the wireless communication device 1200 includes: components for receiving from a second wireless communication device lane features identifying two lane markings; components for receiving a plurality of first features in a first field of view associated with the second wireless communication device, each first feature of the plurality of first features including a respective first key point of a first image captured by the second wireless communication device; and components for receiving from the second wireless communication device a respective two lines two points (2L2P) metric for each first key point pair within a set of first key point pairs based on the two lane markings. The wireless communication device may further include: components for obtaining a plurality of second features in a second field of view associated with the first wireless communication device, each second feature of the plurality of second features including a respective second key point of a second image captured by the first wireless communication device; components for correlating the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features corresponding to the respective first key points within the plurality of first features; components for identifying matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; and components for calculating a relative pose of the first wireless communication device with respect to the second wireless communication device based on the matching key points. In one aspect, the foregoing components may be Figure 12 the processor 1204 shown and configured to perform the functions recited by the foregoing components. In another aspect, the foregoing components may be a circuit or any device configured to perform the functions recited by the foregoing components.

[0181] Of course, in the above example, the circuits included in the processor 1204 are provided only as examples, and other components for performing the described functions may be included in various aspects of the present disclosure, including but not limited to those stored in the computer-readable storage medium 1206 or Figure 1 、 Figure 3 、 Figure 6 and / or Figure 9 any other suitable device or component described in any of them and utilizing instructions for processes and / or algorithms such as those described herein with respect to Figure 11 、 Figure 13 and Figure 14 .

[0182] Figure 15 is a flowchart of an exemplary process 1500 for visual feature sharing according to some aspects. As described below, in particular embodiments within the scope of the present disclosure, some or all of the illustrated features may be omitted, and some of the illustrated features may not be required for all embodiments of the examples. In some examples, the method may be performed by the wireless communication device 1200 as described above and Figure 12 illustrated, by a processor or processing system, or by any suitable component for performing the described functions.

[0183] At block 1502, a wireless communication device may send lane features identifying two lane markings to at least one other wireless communication device. In some examples, the lane features include one or more of the following: lane marking color, type of lane marking, or order of viewing lane markings based on rules. For example, as described above in connection with Figure 12 the communication and processing circuitry 1242, shown and described, together with the visual feature sharing circuitry 1244 and transceiver 1210, may provide components for sending lane sharing features.

[0184] At block 1504, a wireless communication device may send a plurality of features in a field of view associated with the wireless communication device, where each feature of the plurality of features includes a respective key point of an image captured by the wireless communication device. In some examples, each feature of the plurality of features further includes a respective feature descriptor corresponding to the respective key point. In some examples, the plurality of features includes corner features of at least one additional lane marking excluded from two lane markings. For example, the at least one additional lane marking may include a broken line lane marking. In some examples, the plurality of features is located in a space between a pair of lane markings. In this example, the wireless communication device may further send an indication of the pair of lane markings to at least one other wireless communication device. In some examples, the pair of lane markings may include at least one lane marking of the two lane markings. As described above in connection with Figure 12 the communication and processing circuitry 1242, shown and described, together with the visual feature sharing circuitry 1244 and transceiver 1210, may provide components for sending the plurality of features.

[0185] At block 1506, the wireless communication device may send a corresponding two - lines - two - points (2L2P) metric for each key point pair within a set of key point pairs for multiple features based on two lane markings. In some examples, the wireless communication device may further receive, from at least one other wireless communication device, a request for a corresponding additional 2L2P metric associated with additional key point pairs outside the set of key point pairs. The wireless communication device may further send the corresponding additional 2L2P metric to at least one other wireless communication device. In some examples, the request includes a preferred key point in each additional first key point pair to be included in the additional first key point pair for the corresponding additional 2L2P metric. In some examples, the corresponding additional 2L2P metric is based on the preferred key point, two lane markings, and an additional lane marking. In some examples, each additional key point pair in the additional key point pairs includes the preferred key point and a corresponding other first key point within a subset of the multiple features. In some examples, the request includes the additional key point pairs for which the corresponding additional 2L2P metric is requested. In some examples, each additional key point pair in the additional key point pairs includes other key points excluded from the multiple features. In this example, the wireless communication device may further send the additional 2L2P metric and an indication of each such key point including a corresponding key point descriptor associated with each of the other key points.

[0186] In one configuration, the wireless communication device 1200 includes: components for sending to at least one other wireless communication device lane features identifying two lane markings; components for sending multiple features in a field of view associated with the wireless communication device, each of the multiple features including a corresponding key point of an image captured by the wireless communication device; and components for sending a corresponding two - lines - two - points (2L2P) metric for each key point pair within a set of key point pairs for multiple features based on two lane markings. In one aspect, the foregoing components may be Figure 12 the processor 1204 shown and configured to perform the functions recited by the foregoing components. In another aspect, the foregoing components may be a circuit or any device configured to perform the functions recited by the foregoing components.

[0187] Of course, in the above example, the circuits included in the processor 1204 are provided only as examples, and other components for performing the described functions may be included in various aspects of the present disclosure, including but not limited to those described in any other suitable device or component stored in the computer - readable storage medium 1206 or Figure 1 、 Figure 3 、 Figure 6 and / or Figure 9 and utilize instructions of processes and / or algorithms described, for example, herein with respect to Figure 11 and Figure 15 。

[0188] Figures 13 to 15 The processes and / or algorithms shown may include additional aspects, such as any individual aspect or any combination of aspects described below and / or in combination with one or more other processes described elsewhere herein.

[0189] Aspect 1: A method operable at a first wireless communication device, the method comprising: receiving, from a second wireless communication device, lane features identifying two lane markings; receiving a plurality of first features in a first field of view associated with the second wireless communication device, each first feature of the plurality of first features including a respective first key point of a first image captured by the second wireless communication device; receiving, from the second wireless communication device, a respective two lines two points (2L2P) metric for each first key point pair within a set of first key point pairs based on the two lane markings; obtaining a plurality of second features in a second field of view associated with the first wireless communication device, each second feature of the plurality of second features including a respective second key point of a second image captured by the first wireless communication device; associating the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features corresponding to the respective first key points within the plurality of first features; identifying matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; and calculating a relative pose of the first wireless communication device with respect to the second wireless communication device based on the matching key points.

[0190] Aspect 2: The method according to aspect 1, wherein each first feature of the plurality of first features further includes a respective first feature descriptor corresponding to the respective first key point, and each second feature of the plurality of second features further includes a respective second feature descriptor corresponding to the respective second key point, and wherein associating the plurality of first features with the plurality of second features further includes: associating the plurality of first features with the plurality of second features based on the first key points, the second key points, the first feature descriptors, and the second feature descriptors.

[0191] Aspect 3: The method according to aspect 1 or 2, wherein the lane features include one or more of the following: lane marking color, type of lane marking, or order of viewing lane markings based on rules.

[0192] Aspect 4: The method according to any one of aspects 1 to 3, wherein the set of first key point pairs includes corner features of at least one additional lane marking excluded from the two lane markings.

[0193] Aspect 5: The method according to aspect 4, wherein the at least one additional lane marking includes a broken-line lane marking.

[0194] Aspect 6: The method according to any one of aspects 1 to 5, wherein the set of first key point pairs is located in a space between a pair of lane markings, and the method further includes: receiving an indication of the pair of lane markings from the second wireless communication device.

[0195] Aspect 7: The method according to aspect 6, wherein the pair of lane markings includes at least one of the two lane markings.

[0196] Aspect 8: The method according to aspect 1, the method further includes: sending a request for a corresponding additional 2L2P metric associated with an additional first key point pair outside the set of first key point pairs in response to the number of the matched key points being lower than a threshold; receiving the corresponding additional 2L2P metric from the second wireless communication device; and identifying additional matched key points that satisfy the additional corresponding 2L2P metric to calculate the relative pose.

[0197] Aspect 9: The method according to aspect 8, wherein the request includes a preferred key point among the matched key points, and the preferred key point is included in each additional first key point pair for the corresponding additional 2L2P metric.

[0198] Aspect 10: The method according to aspect 9, wherein the corresponding additional 2L2P metric is based on the preferred key point, the two lane markings, and the additional lane marking.

[0199] Aspect 11: The method according to aspect 10, wherein each first key point pair in the additional first key point pairs includes the preferred key point and a corresponding other first key point within a subset of the plurality of first features, and wherein the identifying the additional matched points further includes: identifying the additional matched points that satisfy the additional 2L2P metric without receiving an indication of the corresponding other first key point from the second wireless communication device.

[0200] Aspect 12: The method according to aspect 8, wherein the request includes the additional first key point pairs for which the corresponding additional 2L2P metric is requested.

[0201] Aspect 13: The method according to aspect 8, wherein each first key point pair in the additional first key point pairs includes other first key points excluded from the plurality of first features, and wherein receiving the corresponding additional 2L2P metric further includes: receiving the additional 2L2P metric and an indication of each of the other first key points and the corresponding key point descriptor associated therewith.

[0202] Aspect 14: A method capable of operating at a wireless communication device, the method comprising: sending to at least one other wireless communication device lane features identifying two lane markings; sending a plurality of features in a field of view associated with the wireless communication device, each feature in the plurality of features including a corresponding key point of an image captured by the wireless communication device; and sending a corresponding two-point two-line (2L2P) metric for each key point pair within a set of key point pairs of the plurality of features based on the two lane markings.

[0203] Aspect 15: The method according to aspect 14, wherein each feature in the plurality of features further includes a corresponding feature descriptor corresponding to the corresponding key point.

[0204] Aspect 16: The method according to aspect 14 or 15, wherein the lane features include one or more of the following: lane marking color, type of lane marking, or the order of viewing lane markings based on rules.

[0205] Aspect 17: The method according to any one of aspects 14 to 16, wherein the plurality of features includes corner features of at least one additional lane marking excluded from the two lane markings.

[0206] Aspect 18: The method according to aspect 17, wherein the at least one additional lane marking includes a broken-line lane marking.

[0207] Aspect 19: The method according to any one of aspects 14 to 18, wherein the plurality of features is located in a space between a pair of lane markings, and the method further includes: sending an indication of the pair of lane markings to at least one other wireless communication device.

[0208] Aspect 20: The method according to aspect 19, wherein the pair of lane markings includes at least one lane marking of the two lane markings.

[0209] Aspect 21: The method according to any one of aspects 14 to 20, the method further comprising: receiving, from the at least one other wireless communication device, a request for a respective additional 2L2P metric associated with additional key point pairs outside the set of key point pairs; and sending the respective additional 2L2P metric to the at least one other wireless communication device.

[0210] Aspect 22: The method according to aspect 21, wherein the request includes a preferred key point, the preferred key point being included in each of the additional first key point pairs for the respective additional 2L2P metric.

[0211] Aspect 23: The method according to aspect 22, wherein the respective additional 2L2P metric is based on the preferred key point, the two lane markings, and additional lane markings.

[0212] Aspect 24: The method according to aspect 23, wherein each of the additional key point pairs includes the preferred key point and a respective other first key point within a subset of the plurality of features.

[0213] Aspect 25: The method according to aspect 21, wherein the request includes the additional key point pairs for which the respective additional 2L2P metric is requested.

[0214] Aspect 26: The method according to aspect 21, wherein each of the additional key point pairs includes other key points excluded from the plurality of features, and wherein the sending of the respective additional 2L2P metric further includes: sending the additional 2L2P metric and an indication of each of the key points including a respective key point descriptor associated with each of the other key points.

[0215] Aspect 27: A wireless communication device, the wireless communication device including a transceiver, a memory, and a processor coupled to the transceiver and the memory, the processor being configured to perform the method according to any one of aspects 1 to 13 or 14 to 26.

[0216] Aspect 28: A wireless communication device, the wireless communication device including components for performing the method according to any one of aspects 1 to 13 or 14 to 26.

[0217] Aspect 29: A non-transitory computer-readable medium having instructions stored thereon, the instructions being executable by one or more processors of a wireless communication device to perform the method according to any one of aspects 1 to 13 or aspects 14 to 26.

[0218] Certain aspects of a wireless communication network have been presented with reference to exemplary embodiments. As will be readily appreciated by those skilled in the art, the various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures, and communication standards.

[0219] By way of example, the various aspects may be implemented within other systems defined by 3GPP, such as Long Term Evolution (LTE), Evolved Packet System (EPS), Universal Mobile Telecommunications System (UMTS), and / or Global System for Mobile communications (GSM). The various aspects may also be extended to systems defined by the Third Generation Partnership Project 2 (3GPP2), such as CDMA2000 and / or Evolution-Data Optimized (EV-DO). Other examples may 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 standards, network architecture, and / or communication standards employed will depend on the particular application and the overall design constraints imposed on the system.

[0220] Within this disclosure, the term "exemplary" is used to mean "serving as an example, instance, or illustration". Any particular embodiment or aspect described herein as "exemplary" is not necessarily to be construed as superior or better than other aspects of the disclosure. Similarly, the term "aspect" 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 refer to a direct or indirect coupling between two objects. For example, if object A physically contacts object B, and object B contacts object C, then objects A and C may still be considered to be coupled to each other, even if they are not in direct physical contact with each other. For example, a first object may be coupled to a second object even if the first object has never made direct physical contact with the second object. The term "circuitry" is used broadly, and is intended to include both hardware implementations of electronic devices and conductors (where these electronic devices and conductors are connected and configured to perform the functions described in this disclosure, without limitation as to the type of electronic circuitry) and software implementations of information and instructions (where these information and instructions, when executed by a processor, perform the functions described in this disclosure).

[0221] Figures 1 to 15 One or more of the components, steps, features, and / or functions illustrated therein may 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 may also be added without departing from the novel features disclosed herein. Figure 1 、 Figure 3 、 Figure 6 、 Figure 9 and / orFigure 12 The illustrated apparatus, device, and / or component(s) may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be effectively implemented in software and / or embedded in hardware.

[0222] It should be understood that the specific order or hierarchy of steps in the disclosed methods is an illustration of exemplary processes. It should be understood that based on design preferences, the specific order or hierarchy of steps in these methods may be rearranged. The appended 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 herein.

[0223] The foregoing 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 general principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, where the reference to an element in the singular is not intended to mean "one and only one" but rather "one or more" unless specifically so stated. The term "some," unless specifically stated otherwise, means one or more. The phrase referring to "at least one" of a list of items means any combination of those items, including a single member. As an example, "at least one of a, b, or c" is intended to cover: a; b; c; a and b; a and c; b and c; and a, b, and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known to those of ordinary skill in the art currently or hereafter are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is explicitly recited in the claims.

Claims

1. A first wireless communication device, the first wireless communication device comprising: A transceiver; A memory; And A processor coupled to the transceiver and the memory, the processor being configured to: Receive, via the transceiver, lane features identifying two lane markings from a second wireless communication device; Receive, via the transceiver, a plurality of first features in a first field of view associated with the second wireless communication device, each first feature of the plurality of first features including a respective first key point of a first image captured by the second wireless communication device; Receive, via the transceiver, a respective two-point two-line (2L2P) metric for each first key point pair within a set of first key point pairs of the plurality of first features based on the two lane markings from the second wireless communication device; Obtain a plurality of second features in a second field of view associated with the first wireless communication device, each second feature of the plurality of second features including a respective second key point of a second image captured by the first wireless communication device; Associate the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features corresponding to the respective first key points within the plurality of first features; Identify matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; And Calculate a relative pose of the first wireless communication device with respect to the second wireless communication device based on the matching key points.

2. The first wireless communication device according to claim 1, wherein each first feature of the plurality of first features further includes a respective first feature descriptor corresponding to the respective first key point, and each second feature of the plurality of second features further includes a respective second feature descriptor corresponding to the respective second key point, and wherein the processor is further configured to: Associate the plurality of first features with the plurality of second features based on the first key points, the second key points, the first feature descriptors, and the second feature descriptors.

3. The first wireless communication device according to claim 1, wherein the lane features include one or more of the following: lane marking color, type of lane marking, or order of viewing lane markings based on rules.

4. The first wireless communication device according to claim 1, wherein the set of first key point pairs includes corner features of at least one additional lane marking excluded from the two lane markings.

5. The first wireless communication device according to claim 4, wherein the at least one additional lane marking includes a broken-line lane marking.

6. The first wireless communication device according to claim 1, wherein the set of first key point pairs is located in a space between a pair of lane markings, and wherein the processor is further configured to: Receive an indication of the pair of lane markings from the second wireless communication device.

7. The first wireless communication device according to claim 6, wherein the pair of lane markings includes at least one lane marking of the two lane markings.

8. The first wireless communication device according to claim 1, wherein the processor is further configured to: send a request for corresponding additional two - point two - line (2L2P) metrics associated with additional first key point pairs outside the set of the first key point pairs in response to the number of the matching key points being lower than a threshold; receive the corresponding additional 2L2P metrics from the second wireless communication device; and identify additional matching key points that satisfy the additional corresponding 2L2P metrics to calculate the relative pose.

9. The first wireless communication device according to claim 8, wherein the request includes preferred key points among the matching key points, and the preferred key points are included in each of the additional first key point pairs for the corresponding additional 2L2P metrics.

10. The first wireless communication device according to claim 9, wherein the corresponding additional 2L2P metrics are based on the preferred key points, the two lane markings, and additional lane markings.

11. The first wireless communication device according to claim 10, wherein each of the additional first key point pairs includes the preferred key point and a corresponding other first key point within a subset of the plurality of first features, and wherein the processor is further configured to: identify the additional matching key points that satisfy the additional 2L2P metrics without receiving an indication of the corresponding other first key points from the second wireless communication device.

12. The first wireless communication device according to claim 8, wherein the request includes the additional first key point pairs for which the corresponding additional 2L2P metrics are requested.

13. The first wireless communication device according to claim 8, wherein each of the additional first key point pairs includes other first key points excluded from the plurality of first features, and wherein the processor is further configured to: receive the additional 2L2P metrics and an indication of each of the other first key points and their associated corresponding key point descriptors.

14. A method operable at a first wireless communication device, the method comprising: receiving from a second wireless communication device lane features identifying two lane markings; receiving a plurality of first features in a first field of view associated with the second wireless communication device, each of the plurality of first features including a corresponding first key point of a first image captured by the second wireless communication device; receiving from the second wireless communication device a corresponding two - point two - line (2L2P) metric for each first key point pair within a set of first key point pairs of the plurality of first features based on the two lane markings; obtaining a plurality of second features in a second field of view associated with the first wireless communication device, each of the plurality of second features including a corresponding second key point of a second image captured by the first wireless communication device; Associate the plurality of first features with the plurality of second features to obtain a set of corresponding key points within the plurality of second features that correspond to respective first key points within the plurality of first features; Identify matching key points within the set of corresponding key points that satisfy the respective 2L2P metric; and Calculate a relative pose of the first wireless communication device with respect to the second wireless communication device based on the matching key points.

15. The method according to claim 14, wherein each first feature of the plurality of first features further comprises a respective first feature descriptor corresponding to the respective first key point, and each second feature of the plurality of second features further comprises a respective second feature descriptor corresponding to the respective second key point, and wherein associating the plurality of first features with the plurality of second features further comprises: Associating the plurality of first features with the plurality of second features based on the first key point, the second key point, the first feature descriptor, and the second feature descriptor.

16. A wireless communication device, the wireless communication device comprising: A transceiver; A memory; and A processor coupled to the transceiver and the memory, the processor being configured to: Transmit, via the transceiver, lane features identifying two lane markings to at least one other wireless communication device; Transmit, via the transceiver, a plurality of features in a field of view associated with the wireless communication device, each feature of the plurality of features comprising a respective key point of an image captured by the wireless communication device; and Transmit, via the transceiver, a respective two lines two points (2L2P) metric for each key point pair within a set of key point pairs of the plurality of features based on the two lane markings.

17. The wireless communication device according to claim 16, wherein each feature of the plurality of features further comprises a respective feature descriptor corresponding to the respective key point.

18. The wireless communication device according to claim 16, wherein the lane features comprise one or more of the following: lane marking color, type of lane marking, or order of viewing lane markings based on rules.

19. The wireless communication device according to claim 16, wherein the plurality of features comprise corner features of at least one additional lane marking excluded from the two lane markings.

20. The wireless communication device according to claim 19, wherein the at least one additional lane marking comprises a broken-line lane marking.

21. The wireless communication device according to claim 16, wherein the plurality of features are located in a space between a pair of lane markings, and wherein the processor is further configured to: Transmit an indication of the pair of lane markings to at least one other wireless communication device.

22. The wireless communication device according to claim 21, wherein the pair of lane markings comprises at least one lane marking of the two lane markings.

23. The wireless communication device according to claim 16, wherein the processor is further configured to: Receive a request for a respective additional 2L2P metric associated with an additional key point pair outside the set of key point pairs from the at least one other wireless communication device; and Send the respective additional 2L2P metric to the at least one other wireless communication device.

24. The wireless communication device according to claim 23, wherein the request includes a preferred key point, and the preferred key point is included in each additional key point pair of the additional key point pairs for the respective additional 2L2P metric.

25. The wireless communication device according to claim 24, wherein the respective additional 2L2P metric is based on the preferred key point, the two lane markings, and additional lane markings.

26. The wireless communication device according to claim 25, wherein each additional key point pair of the additional key point pairs includes the preferred key point and a respective other first key point within a subset of the plurality of features.

27. The wireless communication device according to claim 23, wherein the request includes the additional key point pairs for which the respective additional 2L2P metric is requested.

28. The wireless communication device according to claim 23, wherein each additional key point pair of the additional key point pairs includes other key points excluded from the plurality of features, and wherein the processor is further configured to: Send the additional 2L2P metric and an indication of each key point including a respective key point descriptor associated with each of the other key points.

29. A method operable at a wireless communication device, the method comprising: Send to at least one other wireless communication device lane features identifying two lane markings; Send a plurality of features in a field of view associated with the wireless communication device, each of the plurality of features including a respective key point of an image captured by the wireless communication device; And Send a respective two-point two-line (2L2P) metric for each key point pair within a set of key point pairs of the plurality of features based on the two lane markings.

30. The method according to claim 29, wherein each of the plurality of features further includes a respective feature descriptor corresponding to the respective key point.

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