CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of Greece Patent Application No. 20200100265, entitled, “CHANNEL ACCESS FOR VEHICLE-TO-EVERYTHING (V2X) COMMUNICATION IN UNLICENSED SPECTRUM,” filed on May 20, 2020, which is expressly incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to channel access for vehicle-to-everything (V2X) communication in unlicensed spectrum.

INTRODUCTION

[0003] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources.

[0004] A wireless communication network may include a number of base stations or node Bs that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

[0005] A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a transmission from the base station may encounter interference due to transmissions from neighbor base stations or from other wireless radio frequency (RF) transmitters. On the uplink, a transmission from the UE may encounter interference from uplink transmissions of other UEs communicating with the neighbor base stations or from other wireless RF transmitters. This interference may degrade performance on both the downlink and uplink.

71758331.1 [0006] As the demand for mobile broadband access continues to increase, the possibilities of interference and congested networks grows with more UEs accessing the long-range wireless communication networks and more short-range wireless systems being deployed in communities. Research and development continue to advance wireless technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

[0007] Vehicle-to-everything (V2X) technology enables sharing of information from a vehicle to another device or entity that may affect the vehicle, and vice versa. V2X technology is associated with a vehicular communication system that can include one or more aspects or types of communication, such as vehi cl e-to- vehicle (V2V), vehicle-to- infrastructure (V2I), vehicle-to-network (V2N), vehicle-to-pedestrian (V2P), vehicle-to- device (V2D), and vehicle-to-grid (V2G), as illustrative, non-limiting examples. V2X technology can utilize cellular based communication or wireless local area network communication. To illustrate, cellular V2X (C-V2X) is a 3rd Generation Partnership Project (3GPP) standard and uses 3GPP standardized 4G LTE or 5G mobile cellular connectivity to send and receive signals from a vehicle to other vehicles, pedestrians or to fixed objects such as traffic lights in its surroundings. As part of the 3GPP Release 14, C-V2X defines two transmission modes that, together, enable a broad range of use cases. Direct C-V2X, which includes vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-pedestrian (V2P), provides enhanced communication range and reliability in dedicated ITS 5.9 GHz spectrum that’s independent of a cellular network, as well as network communications (V2N) in traditional mobile broadband licensed spectrum.

[0008] Cellular V2X communication typically occurs in a licensed spectrum, such as a sharing spectrum in a licensed cellular band, or a dedicated intelligent transportation system (ITS) spectrum. In the licensed cellular spectrum, V2X communications may share an uplink spectrum in a cellular network. In a dedicated ITS spectrum, V2X communications may occur in a spectrum range which may be regionally defined. However, in some regions, a dedicated spectrum is not guaranteed due to scarcity of spectrum availability. Accordingly, it is conceivable that cellular V2X communications may be deployed in an unlicensed spectrum which may be shared by other technologies, such as wireless-fidelity (Wi-Fi). Additional V2X use of the unlicensed spectrum may add additional traffic to the unlicensed spectrum, create additional competition for access to the unlicensed spectrum, and make accessing the unlicensed spectrum more difficult. SUMMARY

[0009] The following summarizes some aspects of the present disclosure to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in summary form as a prelude to the more detailed description that is presented later.

[0010] One innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a user equipment (UE). The method includes determining that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device. The method also includes transmitting a communication in a second frequency resource in the unlicensed channel in the first slot.

[0011] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus, such as a UE. The apparatus includes at least one processor and a memory coupled with the at least one processor and storing processor-readable instructions that, when executed by the at least one processor, is configured to determine that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device; and initiate transmission of a communication in a second frequency resource in the unlicensed channel in the first slot.

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus configured for wireless communication. The apparatus includes means for determining that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device. The apparatus also includes means for transmitting a communication in a second frequency resource in the unlicensed channel in the first slot.

[0013] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform operations including determining that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device; and initiating transmission of a communication in a second frequency resource in the unlicensed channel in the first slot.

[0014] Other aspects, features, and implementations of the present disclosure will become apparent to a person having ordinary skill in the art, upon reviewing the following description of specific, example implementations of the present disclosure in conjunction with the accompanying figures. While features of the present disclosure may be described relative to particular implementations and figures below, all implementations of the present disclosure can include one or more of the advantageous features described herein. In other words, while one or more implementations may be described as having particular advantageous features, one or more of such features may also be used in accordance with the various implementations of the disclosure described herein. In similar fashion, while example implementations may be described below as device, system, or method implementations, such example implementations can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0016] Figure l is a block diagram illustrating details of an example wireless communication system.

[0017] Figure 2 is a block diagram conceptually illustrating an example design of a base station and a user equipment (UE).

[0018] Figure 3 is a block diagram illustrating an example wireless communication system for vehicle-to-everything (V2X) communication.

[0019] Figure 4 is a diagram conceptually illustrating an example of resource reservation.

[0020] Figure 5 is a flow diagram illustrating an example process of UE operations for channel access.

[0021] Figure 6 is a diagram conceptually illustrating another example of channel access.

[0022] Figure 7 is a diagram conceptually illustrating another example of channel access.

[0023] Figure 8 is a diagram conceptually illustrating another example of channel access.

[0024] Figure 9 is a diagram conceptually illustrating another example of channel access.

[0025] Figure 10 is a flow diagram illustrating another example process of UE operations for

V2X channel access. [0026] Figure 11 is a flow diagram illustrating another example process of UE operations for communication.

[0027] Figure 12 is a block diagram conceptually illustrating a design of a UE.

[0028] Figure 13 is a block diagram conceptually illustrating a design of a network entity.

[0029] Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0030] The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and are not to be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art may appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any quantity of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. Any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0031] The present disclosure provides systems, apparatus, methods, and computer-readable media for accessing a channel in an unlicensed spectrum. To illustrate, a user equipment (UE) may determine whether a first frequency resource in an unlicensed channel is reserved in a first slot by a first device. If the first frequency resource is reserved, the UE may transmit a communication, such as a vehicle-to-everything (V2X) communication, in a second frequency resource in the unlicensed channel in the first slot. For example, the first device may have performed listen-before-talk (LBT) on the unlicensed channel and accessed the first frequency resource based on the LBT, such as an energy based LBT, for a transmission burst of one or more slots. The LBT may include energy detection based on an energy threshold in which a device senses a channel to detect channel occupancy by another device. For example, to sense the channel, the device may perform clean channel assessment (CCA) to detect channel occupancy by another device, such as a UE , a Wi-Fi device, etc. in a unlicensed carrier or unlicensed channel. The device may then transmit in the unlicensed carrier if the CCA indicates that the unlicensed channel is free. In some implementations, the CCA may include a back-off, such as a CAT2, CAT4, etc. Based on a determination by the UE that the first frequency resource is reserved, and that the second frequency resources is available in the first slot, the UE may transmit the communication, such as a V2X communication, in the second frequency resource. Accordingly, the UE may transmit using the second frequency resource without performing an energy based LBT based on a determination that another device would occupy part of frequency resources of the unlicensed channel. By concurrently accessing the unlicensed channel, and without performing an energy based LBT, the UE may increase access to and utilization of the unlicensed channel. For example, multiple devices, such as multiple UEs may be frequency division multiplexed in the unlicensed channel.

[0032] In some implementations, the UE may monitor sidelink transmission in the unlicensed channel to determine resource occupation by other devices. To illustrate, UE may receive sidelink information, such as sidelink control information (SCI), from the first device and perform sidelink decoding on the sidelink information. Based on the decoded sidelink information, the UE may determine whether another device are transmitting via the unlicensed channel in a current slot and whether the other device has reserved a one or more future slots, such as a next slot. If the sidelink decoding indicates that a future slot is reserved by the other device, the UE may transmit in an unreserved resources of the unlicensed channel in the future slot. For example, the UE may transmit in the unreserved resources without performing energy detection based LBT.

[0033] In some implementations, the UE may determine that the UE has a communication, such as a packet, ready for transmission. The UE may be configured to access a channel, such as an unlicensed channel, either based on a sidelink decoding outcome or based on an energy detection (e.g., LBT) outcome. For example, energy detection and sidelink decoding may be two parallel procedures performed by the UE and the UE may access the channel based on either approach. As another example, if no sidelink transmission is decoded/detected, which indicates that no other device is transmitting V2X data, the UE may perform energy detection to determine if channel is free from other technologies, such as Wi Fi. [0034] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some aspects, the present disclosure provides the UE access to a channel in an unlicensed spectrum. For example, the UE may be configured for access the channel in the unlicensed spectrum without performing LBT. By accessing the channel without performing LBT as described herein, the UE may efficiently and quickly access the channel, reduce power consumption, improve utilization of the channel, or a combination thereof.

[0035] This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. One or more aspects of the wireless communication networks described herein may be used or incorporated into a V2X system. In various implementations, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, 5th Generation (5G) or new radio (NR) networks (sometimes referred to as “5G NR” networks/systems/devices), as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

[0036] A CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, and the like. UTRA includes wideband-CDMA (W- CDMA) and low chip rate (LCR). CDMA2000 covers IS-2000, IS-95, and IS-856 standards.

[0037] A TDMA network may implement a radio technology such as Global System for

Mobile Communications (GSM). 3GPP defines standards for the GSM EDGE (enhanced data rates for GSM evolution) radio access network (RAN), also denoted as GERAN. GERAN is the radio component of GSM/EDGE, together with the network that joins the base stations (for example, the Ater and Abis interfaces) and the base station controllers (A interfaces, etc.). The radio access network represents a component of a GSM network, through which phone calls and packet data are routed from and to the public switched telephone network (PSTN) and Internet to and from subscriber handsets, also known as user terminals or user equipments (UEs). A mobile phone operator's network may include one or more GERANs, which may be coupled with UTRANs in the case of a UMTS/GSM network. Additionally, an operator network may include one or more LTE networks, or one or more other networks. The various different network types may use different radio access technologies (RATs) and radio access networks (RANs). [0038] An OFDMA network may implement a radio technology such as evolved UTRA (E-

UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E- UTRA, and GSM are part of universal mobile telecommunication system (UMTS). In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E- UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP), and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3 GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure may describe certain aspects with reference to LTE, 4G, 5G, or NR technologies; however, the description is not intended to be limited to a specific technology or application, and one or more aspects described with reference to one technology may be understood to be applicable to another technology. Indeed, one or more aspects the present disclosure are related to shared access to wireless spectrum between networks using different radio access technologies or radio air interfaces.

[0039] 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. To achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with an ultra- high density (such as ~1M nodes/km2), ultra-low complexity (such as ~10s of bits/sec), ultra- low energy (such as -10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (such as -99.9999% reliability), ultra-low latency (such as - 1 millisecond (ms)), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (such as - 10 Tbps/km2), extreme data rates (such as multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations. [0040] 5G NR devices, networks, and systems may be implemented to use optimized OFDM- based waveform features. These features may include scalable numerology and transmission time intervals (TTIs); a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500MHz bandwidth.

[0041] The scalable numerology of 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive uplink/downlink that may be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet the current traffic needs.

[0042] For clarity, certain aspects of the apparatus and techniques may be described below with reference to exemplary LTE implementations or in an LTE-centric way, and LTE terminology may be used as illustrative examples in portions of the description below; however, the description is not intended to be limited to LTE applications. Indeed, the present disclosure is concerned with shared access to wireless spectrum between networks using different radio access technologies or radio air interfaces, such as those of 5G NR. Additionally or alternatively, certain aspects of the apparatus and techniques described herein, such as LET implementations, 5G NR implementations, other wireless communication implementations, or a combination thereof, may be used for V2X communication.

[0043] Moreover, it should be understood that, in operation, wireless communication networks adapted according to the concepts herein may operate with any combination of licensed or unlicensed spectrum depending on loading and availability. Accordingly, it will be apparent to a person having ordinary skill in the art that the systems, apparatus and methods described herein may be applied to other communications systems and applications than the particular examples provided.

[0044] While aspects are described herein by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, packaging arrangements. For example, aspects or uses may come about via integrated chip embodiments or other non-module-component based devices (such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc.). While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described innovations may occur. Implementations may 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 described aspects. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice. It is intended that innovations described herein may be practiced in a wide variety of implementations, including both large/small devices, chip-level components, multi- component systems (such as RF-chain, communication interface, processor), distributed arrangements, end-user devices, etc. of varying sizes, shapes, and constitution.

[0045] Figure l is a block diagram illustrating details of an example wireless communication system. The wireless communication system may include wireless network 100. The wireless network 100 may, for example, include a 5G wireless network. As appreciated by those skilled in the art, components appearing in Figure 1 are likely to have related counterparts in other network arrangements including, for example, cellular-style network arrangements and non-cellular-style-network arrangements, such as device to device or peer to peer or ad hoc network arrangements, etc. [0046] The wireless network 100 illustrated in Figure 1 includes a number of base stations

105 and other network entities. A base station may be a station that communicates with the UEs and may be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each base station 105 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a base station or a base station subsystem serving the coverage area, depending on the context in which the term is used. In implementations of the wireless network 100 herein, the base stations 105 may be associated with a same operator or different operators, such as the wireless network 100 may include a plurality of operator wireless networks. Additionally, in implementations of the wireless network 100 herein, the base stations 105 may provide wireless communications using one or more of the same frequencies, such as one or more frequency bands in licensed spectrum, unlicensed spectrum, or a combination thereof, as a neighboring cell. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In some other examples, each base station 105 and UE 115 may be operated by a single network operating entity.

[0047] A base station may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, or other types of cell. A macro cell generally covers a relatively large geographic area, such as several kilometers in radius, and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area, such as a home, and, in addition to unrestricted access, may provide restricted access by UEs having an association with the femto cell, such as UEs in a closed subscriber group (CSG), UEs for users in the home, and the like. A base station for a macro cell may be referred to as a macro base station. A base station for a small cell may be referred to as a small cell base station, a pico base station, a femto base station or a home base station. In the example shown in Figure 1, base stations 105d and 105e are regular macro base stations, while base stations 105a-105c are macro base stations enabled with one of 3 dimension (3D), full dimension (FD), or massive MIMO. Base stations 105a-105c take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. Base station 105f is a small cell base station which may be a home node or portable access point. A base station may support one or multiple cells, such as two cells, three cells, four cells, and the like.

[0048] Wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. In some scenarios, networks may be enabled or configured to handle dynamic switching between synchronous or asynchronous operations.

[0049] UEs 115 are dispersed throughout the wireless network 100, and each UE may be stationary or mobile. It should be appreciated that, although a mobile apparatus is commonly referred to as user equipment (UE) in standards and specifications promulgated by the 3rd Generation Partnership Project (3GPP), such apparatus may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, a gaming device, an augmented reality device, vehicular component device/module, or some other suitable terminology. Within the present document, a “mobile” apparatus or UE need not necessarily have a capability to move, and may be stationary. Some non-limiting examples of a mobile apparatus, such as may include examples of one or more of UEs 115, include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a laptop, a personal computer (PC), a notebook, a netbook, a smart book, a tablet, and a personal digital assistant (PDA). A mobile apparatus may additionally be an “Internet of things” (IoT) or “Internet of everything” (IoE) device such as an automotive or other transportation vehicle, a satellite radio, a global positioning system (GPS) device, a logistics controller, a drone, a multi-copter, a quad-copter, a smart energy or security device, a solar panel or solar array, municipal lighting, water, or other infrastructure; industrial automation and enterprise devices; consumer and wearable devices, such as eyewear, a wearable camera, a smart watch, a health or fitness tracker, a mammal implantable device, gesture tracking device, medical device, a digital audio player (e.g., MP3 player), a camera, a game console, etc.; and digital home or smart home devices such as a home audio, video, and multimedia device, an appliance, a sensor, a vending machine, intelligent lighting, a home security system, a smart meter, etc. In one aspect, a UE may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, UEs that do not include UICCs may also be referred to as IoE devices. UEs 115a-115d of the embodiment illustrated in Figure 1 are examples of mobile smart phone- type devices accessing wireless network 100 A UE may also be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. UEs 115e-l 15k illustrated in Figure 1 are examples of various machines configured for communication that access wireless network 100.

[0050] A mobile apparatus, such as the UEs 115, may be able to communicate with any type of the base stations, whether macro base stations, pico base stations, femto base stations, relays, and the like. In Figure 1, a communication link (represented as a lightning bolt) indicates wireless transmissions between a UE and a serving base station, which is a base station designated to serve the UE on the downlink or uplink, or desired transmission between base stations, and backhaul transmissions between base stations. Backhaul communication between base stations of the wireless network 100 may occur using wired or wireless communication links.

[0051] In operation at wireless network 100, base stations 105a-105c serve UEs 115a and

115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. Macro base station 105d performs backhaul communications with base stations 105a- 105c, as well as small cell, base station 105f. Macro base station 105d also transmits multicast services which are subscribed to and received by UEs 115c and 115d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

[0052] Wireless network 100 of embodiments supports mission critical communications with ultra-reliable and redundant links for mission critical devices, such UE 115e, which is a drone. Redundant communication links with UE 115e include from macro base stations 105d and 105e, as well as small cell base station 105f. Other machine type devices, such as UE 115f (thermometer), UE 115g (smart meter), and UE 115h (wearable device) may communicate through wireless network 100 either directly with base stations, such as small cell base station 105f, and macro base station 105e, or in multi -hop configurations by communicating with another user device which relays its information to the network, such as UE 115f communicating temperature measurement information to the smart meter, UE 115g, which is then reported to the network through small cell base station 105f. Wireless network 100 may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such as in a vehicle-to-vehicle (V2V) mesh network between UEs 11 Si ll 5k communicating with macro base station 105e. Additionally, V2V mesh network may include or correspond to a vehicle-to-everything (V2X) network between UEs 115i-l 15k and one or more other devices, such as UEs 115x, 115y.

[0053] Figure 2 is a block diagram conceptually illustrating an example design of a base station 105 and a UE 115. Base station 105 and UE 115 may be one of the base stations and one of the UEs in Figure 1. For a restricted association scenario (as mentioned above), base station 105 may be small cell base station 105f in Figure 1, and UE 115 may be UE 115c or 115D operating in a service area of base station 105f, which in order to access small cell base station 105f, would be included in a list of accessible UEs for small cell base station 105f. Additionally, base station 105 may also be a base station of some other type. As shown in Figure 2, base station 105 may be equipped with antennas 234a through 234t, and UE 115 may be equipped with antennas 252a through 252r for facilitating wireless communications.

[0054] At base station 105, transmit processor 220 may receive data from data source 212 and control information from controller/processor 240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid-ARQ (automatic repeat request) indicator channel (PHICH), physical downlink control channel (PDCCH), enhanced physical downlink control channel (EPDCCH), MTC physical downlink control channel (MPDCCH), etc. The data may be for the PDSCH, etc. Transmit processor 220 may process, such as encode and symbol map, the data and control information to obtain data symbols and control symbols, respectively. Additionally, transmit processor 220 may also generate reference symbols, such as for the primary synchronization signal (PSS) and secondary synchronization signal (SSS), and cell- specific reference signal. Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to modulators (MODs) 232a through 232t. For example, spatial processing performed on the data symbols, the control symbols, or the reference symbols may include precoding. Each modulator 232 may process a respective output symbol stream, such as for OFDM, etc., to obtain an output sample stream. Each modulator 232 may additionally or alternatively process the output sample stream to obtain a downlink signal. For example, to process the output sample stream, each modulator 232 may convert to analog, amplify, filter, and upconvert the output sample stream to obtain the downlink signal. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

[0055] At UE 115, the antennas 252a through 252r may receive the downlink signals from base station 105 and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 254 may further process the input samples, such as for OFDM, etc., to obtain received symbols. MIMO detector 256 may obtain received symbols from demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 258 may process the detected symbols, provide decoded data for UE 115 to data sink 260, and provide decoded control information to controller/processor 280. For example, to process the detected symbols, the receive processor 258 may demodulate, deinterleave, and decode the detected symbols.

[0056] On the uplink, at UE 115, transmit processor 264 may receive and process data (such as for the physical uplink shared channel (PUSCH)) from data source 262 and control information (such as for the physical uplink control channel (PUCCH)) from controller/processor 280. Transmit processor 264 may also generate reference symbols for a reference signal. The symbols from transmit processor 264 may be precoded by TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (such as for SC-FDM, etc.), and transmitted to base station 105. At base station 105, the uplink signals from UE 115 may be received by antennas 234, processed by demodulators 232, detected by MIMO detector 236 if applicable, and further processed by receive processor 238 to obtain decoded data and control information sent by UE 115. Processor 238 may provide the decoded data to data sink 239 and the decoded control information to controller/processor 240.

[0057] Controllers/processors 240 and 280 may direct the operation at base station 105 and

UE 115, respectively. Controller/processor 240 and/or other processors and modules at base station 105 and/or controller/processor 280 and/or other processors and modules at UE 115 may perform or direct the execution of various processes for the techniques described herein, such as to perform or direct the execution illustrated in Figures 3-13, or other processes for the techniques described herein. Memories 242 and 282 may store data and program codes for base station 105 and UE 115, respectively. Scheduler 244 may schedule UEs for data transmission on the downlink or uplink. [0058] Wireless communications systems operated by different network operating entities

(such as network operators) may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (such as time) may be partitioned and allocated to the different network operating entities for certain types of communication.

[0059] For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

[0060] Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

[0061] In some cases, UE 115 and base station 105 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed, such as contention-based, frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs 115 or base stations 105 may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE 115 or base station 105 may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available. A CCA may include an energy detection procedure to determine whether there are any other active transmissions. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

[0062] Figure 3 is a block diagram of an example wireless communications system 300 for

(V2X) message communication. In some examples, the wireless communications system 300 may implement aspects of the wireless network 100. The wireless communications system 300 includes the UE 115 (hereinafter referred to as a “first UE 115”), a second UE 330, a third UE 340, and a network entity 350. Network entity 350 may include or correspond to the base station 105, a network, a network core, road side unit, or another network device, as illustrative, non-limiting examples. Although three UEs, and one network entity are illustrated, in some other implementations, wireless communications system 300 may generally include fewer or more UEs, more than one network entity, or a combination thereof. In some implementations, wireless communication system 300 may include a V2X entity. The V2X entity may include or correspond to a UE 115 as described with reference to Figures 1 and 2. For example, V2X entity 360 may include or correspond to UEs 115i, 115j, 115k to Figure 1.

[0063] In some implementations, the wireless communications system 300 implements a 5G

New Radio (NR) network. For example, the UE 115 may include 5G-capable UEs and 5G capable base stations, such as UEs and base stations configured to operate in accordance with a 5G NR network protocol such as that defined by the 3rd Generation Partnership Project (3 GPP).

[0064] In some implementations, wireless communication system 300 includes a V2X wireless communication system. V2X is a communication system in which information is passed between a vehicle and other entities within the wireless communication network that provides the V2X services. The V2X services may include services for Vehicle-to-Vehicle (V2V), Vehicle-to-Pedestrian (V2P), Vehicle-to-Infrastructure (V2I), and Vehicle-to- Network (V2N). One or more V2X standards aim to develop or support an Advanced Driver Assistance System (ADAS), which assist a driver with critical decisions, such as lane changes, speed changes, overtaking speeds, etc. Low latency communications may be used in V2X and, are therefore suitable for precise positioning. For example, positioning techniques, such as time of arrival (TOA), time difference of arrival (TDOA) or observed time difference of arrival (OTDOA), or any other cellular positioning technique, may be enhanced using assistance from V2X. The V2X wireless communication system can utilize cellular based communication or wireless local area network communication. To illustrate, cellular V2X (C-V2X) is a 3rd Generation Partnership Project (3GPP) standard and uses 3GPP standardized 4G LTE or 5G mobile cellular connectivity to send and receive signals from a vehicle to other vehicles, pedestrians or to fixed objects such as traffic lights in its surroundings.

[0065] In general, there are two modes of operation for V2X services, as defined in Third

Generation Partnership Project (3 GPP) TS 23.285. One mode of operation uses direct wireless communications between V2X entities when the V2X entities are within range of each other. The other mode of operation uses network based wireless communication between entities. The two modes of operation may be combined or other modes of operation may be used if desired.

[0066] The wireless communication of a V2X wireless communication system may be over

Proximity-based Services (ProSe) Direction Communication (PC5) reference point as defined in 3GPP TS 23.303, and may use wireless communications under Institute of Electrical and Electronics Engineers (IEEE) 1609, Wireless Access in Vehicular Environments (WAVE), Intelligent Transport Systems (ITS), and IEEE 802. lip, on the ITS band of 5.9 GHz, 5.725- 5.850 GHz (U-NII-3) or 5.850-5.925 GHz (U-NII-4) spectrum, or other wireless connections directly between entities. In some implementations, the V2X wireless communication system may be over an unlicensed spectrum. Use of an unlicensed spectrum may be subject to various regulatory requirements depending on a region corresponding to the unlicensed spectrum.

[0067] In some implementations, an unlicensed channel bandwidth is 40 MHz. In other implementations, the unlicensed channel bandwidth may be greater than or less than 40 MHz. Additionally, or alternatively, a subcarrier spacing of the OFDM system may be 30 kHz and may include 100 RBs available for signal transmission. In other implementations, the subcarrier spacing may be greater than or less than 30 kHz, may include more than or fewer than 100 RBs, or a combination thereof. The 100 RBs may form 10 subchannels, each of which has 10 RBs (consecutive or uniformly spaced in frequency). In some implementations, a transmission by a UE may occupy one or multiple subchannels. In some implementations, each subchannel may include consecutive RBs in frequency, or the RBs may be scattered across frequency (e.g., an interlaced structure for a subchannel).

[0068] The first UE 115 can include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components can include one or more processors 302 (hereinafter referred to collectively as “processor 302”), one or more memory devices 304 (hereinafter referred to collectively as “memory 304”), an energy detector 310, a sidelink decoder 312, a timer 314, one or more transmitters 316 (hereinafter referred to collectively as “transmitter 316”), and one or more receivers 318 (hereinafter referred to collectively as “receiver 318”). The processor 302 may be configured to execute instructions stored in the memory 304 to perform the operations described herein. In some implementations, the processor 302 includes or corresponds to one or more of the receive processor 258, the transmit processor 264, and the controller/processor 280, and the memory 304 includes or corresponds to the memory 282.

[0069] Memory 282 includes channel access information 306 and one or more thresholds

(herein referred to collectively as “threshold 308”). The channel access information 306 may include information related to channel access operations, such as channel access operations for an unlicensed spectrum. The channel access information 306 may include or indicate a frequency range or bandwidth, a channel bandwidth, a number of subchannels per channel, a number of resource blocks, a number of OFDM symbols per slot, a slot duration, a listen- before-talk (LTB) type, a channel occupancy time (COT), or a combination thereof, as illustrative, non-limiting examples. LBT may ensure that a device transmits (talk) in unlicensed spectrum if the channel is sensed (listen) to be free. The LBT type may be a CAT 2 LBT, a CAT 4 LBT, or a combination thereof. For the CAT 2 LBT, the device may perform clean channel assessment (CCA) in which the devices measures energy in the channel for a certain amount of time and transmits if the channel is indicated to be free based on the CCA. For the CAT 4 LBT, the device may perform the CCA and perform a back-off, such as a random back-off, within a contention window (extended CCA) if channel is sensed free during the CCA period. If the channel is still free during the back-off period, the device may transmit. For the COT, the COT indicates an amount of time, such as a maximum amount of time, a device may occupy a channel for a given transmission burst. For example, the COT may be 4 ms or 10 ms, depending on the region. In some implementations, multiple UEs may share a COT. For example, the multiple UEs may share a channel for sidelink transmission and share a maximum amount of time.

[0070] The threshold 308 may include an energy threshold, a time threshold, an interference threshold, a back-off count threshold, or a RSSI threshold. The energy detector 310 may be configured to perform one or more energy measurements, such as one or more energy measurements on a channel, subchannel, resource block, or a combination thereof, of the unlicensed channel. The sidelink decoder 312 may be configured to decode sidelink information, such as sidelink control information (SCI). The timer 314 may be configured to determine or identify one or more time periods, expiration of one or more time periods, or a combination thereof. For example, the timer 315 may identify or determine expiration of a CCA period, a back-off period, a random back-off period, a contention window, a slot duration, a defer duration, or a combination thereof. In some implementations, the UE 115 may also include a counter configured to count (e.g., increment or decrement) a back-off count.

[0071] The transmitter 316 is configured to transmit data to one or more other devices, and the receiver 318 is configured to receive data from one or more other devices. For example, the transmitter 316 may transmit data to, and the receiver 318 may receive data from, another device, such as the network entity 350, another UE, or a V2X entity, as illustrative, non limiting examples. In some implementations, the transmitter 316 and the receiver 318 may be integrated in one or more transceivers. Additionally, or alternatively, the transmitter 316, the receiver 318, or both may include or correspond to one or more components of the first UE 115 described with reference to Figure 2.

[0072] The second UE 330 can include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components can include one or more processors 332 (hereinafter referred to collectively as “processor 332”), one or more memory devices 334 (hereinafter referred to collectively as “memory 334”), one or more transmitters 336 (hereinafter referred to collectively as “transmitter 336”), and one or more receivers 338 (hereinafter referred to collectively as “receiver 338”). The processor 332 may be configured to execute instructions stored in the memory 334 to perform the operations described herein. In some implementations, the processor 332 includes or corresponds to one or more of the receive processor 258, the transmit processor 264, and the controller/processor 280, and the memory 334 includes or corresponds to the memory 282.

[0073] The transmitter 336 is configured to transmit data to one or more other devices, and the receiver 338 is configured to receive data from one or more other devices. For example, the transmitter 336 may transmit data to, and the receiver 338 may receive data from, another device, such as the network entity 350, another UE, or a V2X entity, as illustrative, non limiting examples. In some implementations, the transmitter 336 and the receiver 338 may be integrated in one or more transceivers. Additionally, or alternatively, the transmitter 336, the receiver 338, or both may include or correspond to one or more components of the UE 115 described with reference to Figure 2. [0074] The third UE 340 can include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components can include one or more processors 342 (hereinafter referred to collectively as “processor 342”), one or more memory devices 344 (hereinafter referred to collectively as “memory 344”), one or more transmitters 346 (hereinafter referred to collectively as “transmitter 346”), and one or more receivers 348 (hereinafter referred to collectively as “receiver 348”). The processor 342 may be configured to execute instructions stored in the memory 344 to perform the operations described herein. In some implementations, the processor 342 includes or corresponds to one or more of the receive processor 258, the transmit processor 264, and the controller/processor 280, and the memory 304 includes or corresponds to the memory 282.

[0075] The transmitter 346 is configured to transmit data to one or more other devices, and the receiver 348 is configured to receive data from one or more other devices. For example, the transmitter 346 may transmit data to, and the receiver 348 may receive data from, another device, such as the network entity 350, another UE, or a V2X entity, as illustrative, non limiting examples. . In some implementations, the transmitter 346 and the receiver 348 may be integrated in one or more transceivers. Additionally, or alternatively, the transmitter 346, the receiver 348, or both may include or correspond to one or more components of the UE 115 described with reference to Figure 2.

[0076] Referring to Figure 4, a diagram illustrating an example of resource reservation is shown. As shown, a first UE (UE-a) communicates via a first frequency resource and a second UE (UE-b) communicates via a second frequency resource. The first UE (UE-a) may include or correspond to the second UE 330, and the second UE (UE-b) may include or correspond to the UE 340. As shown, UE-a communicates via the first resource of the unlicensed channel in a first slot (slot n), a second slot (slot n+1), and a third slot (slot n+2). As shown, UE-b communicates via the second resource of the unlicensed channel in the first slot (slot n) and the second slot (slot n+1).

[0077] During the first slot (slot n), the UE-a may transmit sidelink information 410. The sidelink information 410 may include SCI, as in illustrative, non-limiting example. The sidelink information may include or correspond to the sidelink information 390. The sidelink information may indicate that UE-a reserved the first frequency resource in second slot (slot n+1), the third slot (sot n+2), or both. Accordingly, another UE, such as UE-b or the UE 115, or another device monitoring transmissions on sidelink may determine how long a communications, such as a transmission burst, from UE-a may last. Additionally, during the first slot (slot n), the UE-b is in a receive mode and decodes the side link information 410, which indicates UE-a reserved the second slot (slot n+1) and the third slot (slot n+2). The EE-b may transmit sidelink information that indicates that UE-b reserved the second frequency resource in the third slot (slot n+2). For example, the EE-b may transmit based on a determination that a subchannel (different from the subchannel used by EE-a) is available.

[0078] In some implementations, the UE-a, the UE-b, or both may indicate in each transmission whether next slot has been reserved. Additionally, or alternatively, each of the UE-a and the UE-b may indicate the number of remaining slots in its transmission burst (e.g., a number of slots in upcoming slots). The number of consecutive slots a UE can reserve (e.g., a duration of a transmission burst) may be limited. For example, the number of consecutive slots may be limited to a number that is specified as maximum channel occupancy time (COT). As an illustrative, non-limiting example, a UE’s COT may be limited to 4 ms, which may mean that the UE’s contiguous transmission should not exceed 4 ms. If subcarrier spacing is 30 kHz and each slot is 0.5 ms, then the UE can’t transmit more than 8 consecutive slots.

[0079] The network entity 350 can include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components can include one or more processors 352 (hereinafter referred to collectively as “processor 352”), one or more memory devices 354 (hereinafter referred to collectively as “memory 354”), one or more transmitters 356 (hereinafter referred to collectively as “transmitter 356”), and one or more receivers 358 (hereinafter referred to collectively as “receiver 358”). The processor 352 may be configured to execute instructions stored in the memory 354 to perform the operations described herein. In some implementations, the processor 352 includes or corresponds to one or more of the receive processor 238, the transmit processor 220, and the controller/processor 240, and the memory 354 includes or corresponds to the memory 242.

[0080] The transmitter 356 is configured to transmit data to one or more other devices, and the receiver 358 is configured to receive data from one or more other devices. For example, the transmitter 356 may transmit data to, and the receiver 358 may receive data from, the UE 115. In some implementations, the transmitter 356 and the receiver 358 may be integrated in one or more transceivers. Additionally, or alternatively, the transmitter 356, the receiver 358, or both may include or correspond to one or more components of base station 105 described with reference to Figure 2. [0081] In some implementations, the network entity 350 may include or correspond to a road side unit (RSU). The RSU may include a stationary infrastructure entity supporting V2X applications that can exchange messages with other entities supporting V2X applications. An RSU may be a logical entity that may combine V2X application logic with the functionality of an eNB (referred to as eNB-type RSU) or UE (referred to as UE-type RSU).

[0082] In some implementations, transmissions of multiple UEs may be frequency division multiplexed in an unlicensed channel. For example, frequency resources of a channel may form multiple subchannels and a UE may transmit in one or multiple subchannels. Additionally, or alternatively; each subchannel may include one or multiple RBs (contiguous or non-contiguous RBs in frequency). Resources in time-domain form slots, and each slot may include multiple OFDM symbols.

[0083] During operation of the wireless communications system 300, the first UE 115 may monitor an unlicensed channel, a subchannel of the unlicensed channel, a resource block of the unlicensed channel, or a combination thereof. For example, the first UE 115 may monitor for sidelink information in a slot, such as a current slot. To illustrate, the first UE 115 monitor a current slot and receive sidelink information 390 from the second UE 330 via a first frequency resource. Additionally, or alternatively, the first UE 115 may monitor the current slot and optionally (as indicated by a dashed box) receive sidelink information 391 from the third UE 340 via a frequency resource that is different from the first frequency resource. The sidelink information 390, 391 may include or correspond to sidelink control information (SCI). Additionally, or alternatively, the sidelink information 390, 391 may indicate whether one or more slots are reserved, a COT, or a combination thereof.

[0084] The first UE 115 may perform one or more sidelink decoding operations. For example, the first UE 115 may perform sidelink decoding on the sidelink information 390 using the sidelink decoder 312. If the first UE 115 determines that a sidelink transmission is detected in the current slot (e.g., SCI decoding successful), the first UE 115 may determine whether a resource, such as a frequency resource, in a next or future slot has been reserved based on the decoded sidelink information. For example, based on detection and successful decoding of the sidelink information, the first UE 115 may determine whether the first frequency resource is reserved by the second UE 330 in a next slot.

[0085] The first UE 115 may determine whether all resources in a next slot have been reserved. For example, the first UE 115 may determine whether all frequency resources of an unlicensed spectrum or all frequency resources of an unlicensed channel are reserved in a next slot, based on decoding of sidelink information in current slot (or previous slots). If all frequency resources in next slot have been reserved (e.g., there are no resources available for the first UE V2X transmission in next slot), the first UE 115 may wait and decode sidelink control information in the next or future slot.

[0086] If the first UE 115 determines that there is one or more available frequency resources, such as one or more subchannels or one or more resource blocks, available in the next slot, the first UE 115 may select one or multiple frequency resources (e.g., one or multiple subchannels) from the identified unreserved subchannels in the next slot. Selection of the frequency resource may be a random selection or based on a measurement of the one or more available frequency resources in the current slot. In some implementations, the first UE 115 may select the frequency resource that has a lowest measured RSSI in the current slot. This means that a measurement performed in resource in current slot may be projected to next slot; e.g., for a resource in next slot, it has a measurement value that corresponds to a measurement performed in current slot (e.g., the measurement on the same frequency resource in current slot). The first UE 115 may then transmit a message 392, such as a V2X message, in the selected frequency resource in the next slot. Additionally, or alternatively, the first UE 115 may compare measured RSSI for each of the one or more available frequency resources and compare each measured RSSI to a threshold. In some implementations, the first UE 115 may only select a frequency resource if the measured RSSI is less than or equal to the threshold. Accordingly, in some situation, even if the first UE 115 identifies one or more available frequency resources in the next slot, the first UE 115 may not select or use any of the one or more available frequency resources for transmission in the next slot. In another implementation, the first UE may perform RSRP measurement and select resource based on RSRP measurements and a threshold.

[0087] If the first UE 115 determines that there are not reserved frequency resources in the next slot, e.g., no V2X resource reserved for next slot, the first UE 115 may perform CCA to determine whether the channel is free in the next slot. To determine whether the channel is free in the next slot, the first UE 115 may perform energy detection based channel sensing. For example, the first UE 115 may use energy detector 310 to perform the energy detection. The first UE 115 may start the CCA at the end of the current slot. The first UE 115 may perform the energy detection with or without a back-off, such as a random back-off

[0088] In some implementation, if the first UE 115 does not detect or successfully decode sidelink information in the current slot when the first UE 115 has a packet, such as a V2X packet, is available or ready for transmission, the first UE 115 may perform CCA to determine if channel is free. The first UE 115 may perform the energy detection with or without a back-off, such as a random back-off

[0089] If energy detected for a channel in the current slot is greater than or equal to a threshold, the first UE 115 may determine that the channel is busy. For example, the channel may be busy due to channel occupancy by other technology or devices (e.g., a Wi-Fi device), or there may be insufficient signal-to-noise ratio (SNR) for sidelink decoding. To illustrate, the channel may be occupied during the current slot by the network entity 350 which transmits a message 394 in the current slot. Based on a determination that the channel is busy, the first UE 115 may perform CCA with a back-off, such as a random back-off. To illustrate, in some implementations, the first UE 115 may perform LBT with a random back off within a contention window based on a determination that the channel is busy. If energy detected for the channel in the current slot is less than (or equal to) the threshold, the first UE 115 may transmit sidelink information, such as a reservation signal or sidelink control/data channel transmission. Alternatively, if energy detected for the channel in the current slot is less than (or equal to) the threshold, the first UE 115 may perform a back-off, such as a random back-off, may keep sensing, and may transmit at the end of a contention window if the channel is free; or keep sensing and transmit starting from next slot.

[0090] In some implementations, to perform CCA to determine if channel is free, the first UE

115 may sense the channel for an amount of time (referred to herein as a “defer period”), such as 25 ps, as an illustrative, non-limiting example. The first UE 115 may determine an energy level (of a channel, subchannel, resource block, or symbol) during the defer period and determine if the energy level is greater than or equal to an energy threshold. If the energy level is greater than or equal to the energy threshold, the first UE 115 may determine that the channel is busy.

[0091] In some implementations related to transmission of the message 392 by the first UE

115 based on sidelink decoding, such as SCI decoding, a contiguous transmission duration/burst by the first UE 115 may not exceed the duration of slots that already been reserved by other UE(s) (since COT is initiated by other UE(s)). For example, if the first UE 115 has a packet arrival or ready for transmission and decodes the sidelink information 390 sent by the second UE 330, the decoded sidelink information may indicate reservation of one or more resource in one or more upcoming slots. To illustrate, the sidelink information 390 from the second UE 330 may indicate that a transmission burst from the second UE 330 would last to the next two slots, and the sidelink information 391 from the third UE 340 may indicate that a transmission burst from the third UE 340 would last to the next three slots. The first UE 115 may determine that a transmission burst of the first UE 115 cannot be more than three slots.

[0092] In some implementations related to transmission of the message 392 by the first UE

115 based on sidelink decoding, such as SCI decoding, a contiguous transmission duration/burst by the first UE 115 may not exceed the first UE’s 115 COT limitation as long as there is resource reserved by other UE(s) or other devices. For example, the first UE 115 may transmit spanning multiple slots, as long as the duration of the transmission does not exceed first UE’s 115 COT limitation, and the starting slot of the transmission burst of the first UE 115 has resource(s) reserved by other UEs or devices.

[0093] In some implementations, the first UE may transmit based on sidelink decoding

(without LBT) based on a priority of the traffic the first UE 115 has to transmit. For example, the first UE 115 transmit if the first UE 115 has high priority traffic. Stated differently, the first UE 115 may transmit, as described herein, if the transmission has a priority higher than or equal to a priority threshold (e.g., 308).

[0094] As an illustrative, non-limiting example of operation of wireless communications system 300, the unlicensed channel bandwidth may be 40 MHz and subcarrier spacing of the OFDM system is 30 kHz, with 100 RBs available for signal transmission. The 100 RBs may form 10 subchannels in which each subchannel has 10 RBs, such as 10 RBs that are consecutive or non-consecutive (e.g., uniformly spaced) in a frequency domain. A UE’s transmission may occupy one or multiple subchannels.

[0095] The first UE 115 may determine that the first UE 115 has a packet, such as message

392, ready for transmission in a first slot (slot n). The first UE’s transmission may need 2 subchannels. The first UE 115 may have received and decoded to sidelink transmissions (e.g., two SCIs decoded) in slot n, such as sidelink information 390 from the second UE 220 and the sidelink information 391 from the third UE 340. The second UE’s 330 sidelink transmission may occupy one subchannel, and the sidelink information 390 may indicate the second UE’s 330 COT/transmission burst will end in a slot n+3. The third UE’s 340 sidelink transmission may occupy three subchannels, the third UE’s 334 sidelink information 391 may indicate the third UE’s 340 COT/transmission burst will end in a slot n+2. The first UE 115 may determine that there are six remaining subchannels available in slot n+1 and the first UE 115 may select two subchannels from the six available subchannels and transmits in slot n+1 in the two selected subchannels. It is noted that the first UE 115 and the second UE 220 may have both acquired corresponding resources for transmission based on sidelink decoding or LBT (energy detection). [0096] In some implementations, the first UE’s 115 COT/duration of burst may not exceed a number of slots, such as three slots as an illustrative, non-limiting example. To illustrate, three slots may not be exceed because the first UE 115 did not perform LBT, so the first UE 115 may transmit in time resources (e.g., slots) that were acquired by other UEs, such as the second UE 330 which may have acquire resources via LBT and its burst ends in slot n+3. Accordingly, the first UE 115 may not transmit beyond slot n+3. If the first UE 115 needs more slots to finish its transmission, the first UE 115 may perform LBT (energy detection based channel sensing) to acquire one or more resources after slot n+3.

[0097] In some other implementations, the first UE’s 115 COT/duration may extend beyond slot n+3. For example, if a duration of burst/COT of the first UE’s transmission does not exceed the first UE’s COT limitation, the first UE’s 115 transmission may last to slot n+4 (or longer) even though the decoded sidelink transmissions end in slot n+3.

[0098] Thus, Figure 3 describes accessing an unlicensed channel. To illustrate, the unlicensed channel may be accessed for V2X communication. In some implementations, the first UE 115 may be configured for access the channel in the unlicensed spectrum without performing LBT. By accessing the channel without performing LBT as described herein, the first UE 115 may efficiently and quickly access the channel, reduce power consumption, improve utilization of the channel, or a combination thereof.

[0099] Referring to Figure 5, a flow diagram illustrating an example process 500 of UE operations for channel access is shown. For example, the channel access may include or correspond to V2X channel access. In some implementations, the process 500 may be performed by the UE 115, 330, 340. In some other implementations, the process 500 may be performed by an apparatus configured for wireless communication. For example, the apparatus may include at least one processor, and a memory coupled to the processor. The processor may be configured to perform operations of the process 500. In some other implementations, the process 500 may be performed or executed using a non-transitory computer-readable medium having program code recorded thereon. The program code may be program code executable by a computer for causing the computer to perform operations of the process 500.

[00100] As illustrated at block 510, the UE decodes one or more SCIs. The one or more SCIs may include or correspond to the sidelink information 390, the sidelink information 391, or a combination thereof. The UE may decode the one or more SCIs using the sidelink decoder 312. The one or more SCIs may have been received by the UE during a slot, such as a current slot. [00101] At block 512, the UE determines whether or not the UE has information or a message to transmit. The information or the message may include or correspond to V2X information or a V2X message, as illustrative, non-limiting examples. Based on a determination that the EE does not have information or a message to transmit, the process 500 advances to 510. Alternatively, based on a determination that the EE has information or a message to transmit, the process 500 advances to block 514.

[00102] At block 514, the EE determines whether the SCI decoding was successful. Based on a determination that the SCI decoding was unsuccessful, the process 500 advances to block 516. Alternatively, based on a determination that the SCI decoding was successful, the process 500 advances to block 518.

[00103] At block 518, the UE determines whether any resources in a next slot are reserved based on the decoded SCI. Based on a determination that a resource in the next slot is not reserved, the process 500 advances to block 520. At block 520, the UE waits until the end of the slot, such as the current slot. After waiting until the end of the slot, the process advances to block 516. Alternatively, based on a determination that a resource in the next slot is reserved, the process advances to block 522.

[00104] At block 522, the UE determines whether the next slot has a frequency-resource available. Based on a determination that no frequency-resources are available in the next slot, the process advances to block 510 to decode one or more SCIs in a next slot. Alternatively, based on a determination that one or more frequency-resources are available in the next slot, the process 500 advances to block 524. At block 524, the UE transmits information or a message in the next slot.

[00105] At block 516, the UE determines whether the channel is idle for a defer duration. For example, the defer duration may be 25 microseconds, as an illustrative, non-limiting example. To illustrate, the UE may use the timer 314 to determine the defer duration. Additionally, or alternatively, the UE may use the energy detector 310 to determine if the channel is free during the defer duration. Based on a determination that the channel was not idle for the defer duration, the process advances to block 530. Alternatively, based on a determination that the channel was idle for the defer duration, the process 500 advances to block 526. Accordingly, the UE may not use a random back-off if the channel is sensed free, which may correspond to a CAT 2 LBT. At block 526, the UE transmits a reservation signal. For example, the UE may transmit the reservation signal immediately following expiration of the defer duration. After sending the reservation signal at block 526, the process 500 advances to block 524. [00106] At block 530, the UE generates a random counter value N, where N is an integer. In some implementations, the random counter value N may include or correspond to a back-off period. To illustrate, if the channel is sensed as busy, the UE may use a random back-off within a contention window, which may correspond to a CAT 4 LBT. Additionally, or alternatively, generation of the random counter value N may include or correspond to an extended CCA.

[00107] At block 532, the UE determines whether the channel is idle for a defer duration. For example, the defer duration may be 25 microseconds. To illustrate, the UE may use the timer 314 to determine the defer duration. Based on a determination that the channel has not been idle for the defer duration, the process 500 advances again to block 532. Alternatively, based on a determination that the channel has been idle for the defer duration, the process 500 advances to block 534.

[00108] At block 534, the UE determines whether the random counter value N is equal to zero. Based on a determination that the random counter value N is equal to zero, the process 500 advances to block 526. Alternatively, based on a determination that the random counter value N is not equal to zero, the process 500 advances to block 536. At block 536, the UE senses the channel for a sensing slot duration. For example, the sensing slot duration may be 9 microseconds, as an illustrative, non-limiting example. To illustrate, the UE may use the timer 314 to determine the sensing slot duration. After sensing the channel for the sensing slot duration, the process 500 advances to block 538.

[00109] At block 538, the UE determines whether the channel has been idle. For example, the UE may determine whether or not the channel was idle during the sensing slot duration. Based on a determination that the channel was not idle, the process 500 advances to block 532. Alternatively, based on a determination that the channel was idle, the process advances to block 540.

[00110] At block 540, the UE updates the random counter value N to be equal to N-l. The process 500 then advances to block 534.

[00111] Thus, the process 500 enables the UE to access an unlicensed spectrum, such as a subchannel, a resource block, or a channel of the unlicensed spectrum. By accessing the unlicensed spectrum, the UE may transmit a V2X communication, such as a cellular V2X communication, which may be shared by other technologies, such as wireless-fidelity (Wi Fi). The UE may efficiently access the unlicensed spectrum by utilizing an available frequency resource of an unlicensed channel. In some aspects, the UE does not utilize a back-off if the channel is sensed free by energy detection, which may correspond to CAT 2 LBT. In other aspects, the UE may utilize a back-off (e.g., a back-off within a contention window) if channel is sensed busy by energy detection, which may correspond to CAT 4 LBT.

[00112] Figures 6-9 are diagrams illustrating examples of channel access. Referring to Figure 6, access of an unlicensed channel by a first UE (UE1) and a second UE (UE2) is shown. The first UE (UE1) may include or correspond to the UEs 330, 340, and the second UE (UE2) may include or correspond to the UE 115. As shown, UE 1 communicates via a first resource of the unlicensed channel in a first slot (slot n) and a second slot (slot n+1). During the first slot (slot n), the UE1 may transmit sidelink information 610 that includes an indication that UE1 reserved a number of frequency resources in the second slot (slot n+1).

[00113] During the first slot (slot n), the UE2 may determine whether there are any unreserved resources of the unlicensed channel available during the second slot (slot n+1). The UE2 may determine whether there are any unreserved resources based on SCI decoding, or SCI decoding and a measurement. For SCI decoding and a measurement, the UE 2 may measure an energy level or other metrics, such as receives signal strength indicator (RSSI) or RSRP. For example, the UE2 may measure one or more subchannels, such as all subchannels, for a current slot. If the measured RSSI of a subchannel is greater than or equal to a threshold, the UE2 may assume that the same subchannel in a next slot has high RSSI and exclude the subchannel as a subchannel selection candidate, such as available subchannels. In some implementations, when multiple subchannels are available - e.g., multiple subchannel selection candidates, the UE2 may select one or more subchannels for transmission. For example, the UE2 may select the one or more subchannels based on lowest RSSI or RSRP value, based on first available identified, based on farthest from a reserved subchannel, randomly select from resources that are available (available means the resource has not been reserved and/or RSSI/RSRP measurement is below a threshold), another criterion, or a combination thereof.

[00114] As shown in Figure 6, the UE2 determines, during the first slot, that the UE2 has a packet for transmission. Based on or independent of the determination that the UE2 has the packet for transmission, the UE2 receives the sidelink information 610 from the UE1 and performs SCI decoding. Based on successful SCI decoding of the sidelink information 610, the UE2 may determine that the UE1 reserved the first frequency resource for the second slot (slot n+1). Stated differently, the UE2 may determine that a second frequency resource, such as a subchannel or resource block, is available for the second slot (slot n+1) based on the decoded SCI. Accordingly, the UE2 may transmit the packet in the second slot (slot n+1). [00115] Referring to Figure 7, access of an unlicensed channel by a first UE (UE1) and a second UE (UE2) is shown. The first UE (UE1) may include or correspond to the UEs 330, 340, and the second UE (UE2) may include or correspond to the UE 115. As shown, UE1 communicates via a first resource of the unlicensed channel in a first slot (slot n). During the first slot (slot n), the UE1 may transmit sidelink information 610 that does not include an indication that UE1 reserved the second slot (slot n+1).

[00116] During the first slot (slot n), the UE2 may determine whether there are any unreserved resources of the unlicensed channel available during the second slot (slot n+1). The UE2 may determine whether there are any unreserved resources based on SCI decoding. As shown in Figure 7, the UE2 determines, during the first slot, that the UE2 has a packet for transmission. Based on or independent of the determination that the UE2 has the packet for transmission, the UE2 receives the sidelink information 610 from the UE1 and performs SCI decoding. Based on successful SCI decoding of the sidelink information 610, the UE2 may determine that the UE1 has not reserved the first frequency resource for the second slot (slot n+1). To illustrate, the decoded SCIs may indicate a transmission burst of the UE1 ends in the first slot (slot n).

[00117] Based on the successful SCI decoding and a determination that the UE1 has not reserved the first frequency resource, the UE2 performs CCA 720 starting at the end of the first slot (slot n). To illustrate, the UE2 performs energy detection to determine whether the unlicensed channel, such as the first frequency resource, a second frequency resource, or the entire channel, is free. In response to a determination that the channel is free, the UE2 may transmit to reserve the channel (or frequency resource). To illustrate, if response to a determination that the channel is free, the UE2 may transmit immediately to reserve the channel, which may be known as CAT 2 LBT - CCA without random back-off. Alternatively, the UE2 if response to a determination that the channel is free, the UE2 may transmit following a contention window 730. The transmission in the second slot (slot n+1) may being with a reservation signal, data channel transmission, or other signals.

[00118] In some implementations, the UE2 may transmit following end of transmission in the first slot (slot n) without LBT. To illustrate, the UE2 may transmit in the second slot (slot n+1) based on the successful decoding of the SCI when the decoded transmission has not exceeded a duration limitation, such as a COT limitation of the UE1. In some implementations, the UE2 may transmit after a gap that follows end of current slot transmission, and gap has a time duration no greater than a threshold (e.g., 16us). [00119] Referring to Figure 8, access of an unlicensed channel in relation to a first UE (UE1) and a second UE (UE2) is shown. The first UE (UE1) may include or correspond to the UEs 330, 340, and the second UE (UE2) may include or correspond to the UE 115. As shown, UE1 does not communicate via a first resource of the unlicensed channel in a first slot (slot n).

[00120] During the first slot (slot n), the UE2 may determine whether there are any unreserved resources of the unlicensed channel available during the second slot (slot n+1). For example, the UE2 may determine whether there are any unreserved resources based on SCI decoding. As shown in Figure 8, the UE2 determines, during the first slot, that the UE2 has a packet for transmission. Based on or independent of the determination that the UE2 has the packet for transmission, performs SCI decoding. Based on no SCIs being successfully decoded, the UE2 may determine that the channel has not been reserved for sidelink communication (V2X) in the second slot (slot n+1). In some implementations, this may imply that there is no active COT available that can be shared with the UE2.

[00121] Based on a determination that the channel has not been reserved for the second slot (slot n+1) (or there is no COT available), the UE2 may perform CCA to sense if the channel is free. For example, the CCA to sense if the channel is free may include or correspond to CAT2 LBT or CAT4 LBT. To illustrate, the UE2 may sense the channel to be free if a measured energy level during a defer period (CCA) 820 is less than or equal to the energy threshold, such as the threshold 308.

[00122] Based on a determination that the channel is sensed to be free, the UE2 may transmit in the channel. For example, the transmission may start with a reservation signal to reserve the channel or sidelink data/control channel (e.g., a partial-slot transmission). In some implementations, the reservation signal may be transmitted immediately following expiration of the defer duration. Alternatively, the UE2 may transmit following a contention window 830, which may correspond to CAT 4 LBT. In some implementations, the UE2 may not transmit until a next slot, e.g., although the channel is free at the end of the contention window, the UE may not transmit because it may not be starting of the next slot. The UE may keep sensing the channel and transmit at the start of next slot if the channel is still free then.

[00123] Referring to Figure 9, access of an unlicensed channel in relation to a first UE (UE1) and a second UE (UE2) is shown. The first UE (UE1) may include or correspond to the UEs 330, 340, and the second UE (UE2) may include or correspond to the UE 115. As shown, UE1 does not communicate via a first resource of the unlicensed channel in a first slot (slot n).

[00124] During the first slot (slot n), the UE2 may determine whether there are any unreserved resources of the unlicensed channel available during the second slot (slot n+1). For example, the UE2 may determine whether there are any unreserved resources based on SCI decoding. As shown in Figure 8, the UE2 determines, during the first slot, that the UE2 has a packet ready for transmission. Based on or independent of the determination that the UE2 has the packet for transmission, performs SCI decoding. Based on no SCIs being successfully decoded, the UE2 may determine that the channel has not been reserved for sidelink communication (V2X) in the second slot (slot n+1). In some implementations, this may imply that there is no active COT available that can be shared with the UE2.

[00125] Based on a determination that the channel has not been reserved for the second slot (slot n+1) (or there is no COT available), the UE2 may perform CCA to sense if the channel is free. For example, the CCA to sense if the channel is free may include or correspond to CAT2 LBT or CAT4 LBT. To illustrate, the UE2 may sense the channel to be free if a measured energy level during a defer period (CCA) 820 is less than or equal to the energy threshold, such as the threshold 308.

[00126] The UE2 may perform CCA to determine whether the channel is free. For example, the UE2 may detect energy during the CCA, such as a defer period 920, and determine whether the detected energy is greater than or equal to an energy threshold. The energy threshold may include or correspond to threshold 308. Based on a determination that the detected energy is greater than or equal to the energy threshold, the UE2 may determine that the sensed channel is busy. The detected energy may be greater than or equal to the energy threshold due to the channel being occupied by another technology or device, such as Wi-Fi or a Wi-Fi device.

[00127] Based on a determination that the detected energy is greater than or equal to the energy threshold, the UE2 may perform an extended CCA, which may or may not further include a back-off, such as a predetermined back-off or a random back-off To illustrate, as shown, the UE may generate a random counter value and the UE2 may sense the channel for an extended CCA based on the random counter value. The back-off counter value may be within the range of contention window. Based on the extended CCA, the UE2 may determine that the channel is free and start the counter for a number of sensing slots 930. After the UE2 determines that the channel is free for the back-off period, the UE2 may transmit to reserve the channel. For example, the UE2 may immediately transmit to reserve the channel following the end of the back-off period. To reserve the channel, the UE2 may transmit a reservation signal or sidelink data/control. The UE2 may transmit to reserve the channel prior to a beginning of a next slot. After the UE2 transmits to reserve the channel, the UE2 may wait for a time period 940 prior to transmission during the next slot, such as transmission of a V2X message. Alternatively, the UE may keep sensing (although the counter has already reached 0) until the start of next slot, and transmit in next slot.

[00128] Thus, Figures 6-9 describe various techniques that may be used by a UE to access an unlicensed spectrum, such as a subchannel, a resource block, or a channel of the unlicensed spectrum. By accessing the unlicensed spectrum, the UE may transmit a V2X communication, such as a cellular V2X communication, which may be shared by other technologies, such as wireless-fidelity (Wi-Fi). The UE may efficiently access the unlicensed spectrum by utilizing an available frequency resource of an unlicensed channel.

[00129] Referring to Figure 10, a flow diagram illustrating an example process 1000 of UE operations for channel access is shown. For example, the channel access may include or correspond to V2X channel access. In some implementations, the process 1000 may be performed by the UE 115, 330, 340. In some other implementations, the process 1000 may be performed by an apparatus configured for wireless communication. For example, the apparatus may include at least one processor, and a memory coupled to the processor. The processor may be configured to perform operations of the process 1000. In some other implementations, the process 1000 may be performed or executed using a non-transitory computer-readable medium having program code recorded thereon. The program code may be program code executable by a computer for causing the computer to perform operations of the process 1000.

[00130] As illustrated at block 1010, the UE decodes one or more SCIs. The one or more SCIs may include or correspond to the sidelink information 390, the sidelink information 391, or a combination thereof. The UE may decode the one or more SCIs using the sidelink decoder 312. The one or more SCIs may have been received by the UE during a slot, such as a current slot. As illustrative, the UE may keep decoding sidelink transmissions in the unlicensed channel if it is not in transmitter mode.

[00131] At block 1012, the UE determines whether or not the UE has information or a message to transmit. The information or the message may include or correspond to V2X information or a V2X message, as illustrative, non-limiting examples. Based on a determination that the UE does not have information or a message to transmit, the process 1000 advances to 1010. Alternatively, based on a determination that the UE has information or a message to transmit, the process 1000 advances to block 1014.

[00132] At block 1014, the UE determines whether the SCI decoding was successful. Based on a determination that the SCI decoding was unsuccessful, the process 1000 advances to block 1016. Alternatively, based on a determination that the SCI decoding was successful, the process 1000 advances to block 1018.

[00133] At block 1018, the UE determines whether any resources in a next slot are reserved based on the decoded SCI. Based on a determination that a resource in the next slot is not reserved, the process 1000 advances to block 520. At block 1020, the UE waits until the end of the slot, such as the current slot. After waiting until the end of the slot, the process advances to block 1016. Alternatively, based on a determination that a resource in the next slot is reserved, the process advances to block 1022.

[00134] At block 1022, the UE determines whether the next slot has a frequency -resource available. Based on a determination that no frequency-resources are available in the next slot, the process advances to block 1010 to decode one or more SCIs in a next slot. Alternatively, based on a determination that one or more frequency-resources are available in the next slot, the process 1000 advances to block 1024. At block 1024, the UE transmits information or a message in the next slot.

[00135] At block 1016, the UE determines whether the channel is idle for a defer duration. For example, the defer duration may be 25 microseconds, as an illustrative, non-limiting example. To illustrate, the UE may use the timer 314 to determine the defer duration. Additionally, or alternatively, the UE may use the energy detector 310 to determine if the channel is free during the defer duration. Based on a determination that the channel was not idle for the defer duration, the process advances to block 1016. Alternatively, based on a determination that the channel was idle for the defer duration, the process 1000 advances to block 1026.

[00136] At block 1026, the UE generates a random counter value N, where N is an integer. In some implementations, the random counter value N may include or correspond to a back-off period. Accordingly, if the channel is sensed as busy, the UE may use a random back-off within a contention window, which may correspond to a CAT 4 LBT.

[00137] At block 1028, the UE determines whether the random counter value N is equal to zero. Based on a determination that the random counter value N is equal to zero, the process 1000 advances to block 1030. At block 1030, the UE transmits a reservation signal. For example, the UE may immediately transmit the reservation signal following the determination that the random counter value N is equal to zero. After sending the reservation signal at block 1030, the process 500 advances to block 1024. Alternatively, based on a determination that the random counter value N is not equal to zero at block 1028, the process 1000 advances to block 1032.

[00138] At block 1032, the UE updates the random counter value N to be equal to N-l. The process 1000 then advances to block 1034. At block 1034, the UE senses the channel for a sensing slot duration. For example, the sensing slot duration may be 9 microseconds, as an illustrative, non-limiting example. To illustrate, the UE may use the timer 314 to determine the sensing slot duration. After sensing the channel for the sensing slot duration, the process 10000 advances to block 1036.

[00139] At block 1036, the UE determines whether the channel is idle for a defer duration. For example, the defer duration may be 25 microseconds. To illustrate, the UE may use the timer 314 to determine the defer duration. Based on a determination that the channel has been idle for the defer duration, the process 1000 advances to block 1028. Alternatively, based on a determination that the channel has not been idle for the defer duration, the process 1000 advances to block 1040.

[00140] At block 1040, the UE freezes or maintains the random counter value N. After block 1040, the process 1000 advances to block 1042. At block 1042 the UE determines whether the channel is idle for a defer duration. For example, the defer duration may be 25 microseconds, as an illustrative, non-limiting example. Based on a determination that the channel was not idle for the defer duration, the process advances to block 1042. Alternatively, based on a determination that the channel was idle for the defer duration, the process 1000 advances to block 1028.

[00141] Thus, as compared to the process 500, the process 1000 performs a random back-off after sensing even if the channel is sensed to be free in an initial CCA, such as described with reference to block 1016.

[00142] Referring to Figure 11, a flow diagrams illustrating an example process 1100 of UE operations for communication is shown. For example, example blocks of the process of Figure 11 may cause the UE to access a channel in an unlicensed spectrum, according to one aspect of the present disclosure. For example, the UE 1200 may access the channel to transmit a communication, such as a V2X message. In some implementations, the processes 1100 of Figure 11 may be performed by the UE 115, 330, 340, network entity 350, a V2X entity, or another device. In some other implementations, the process 1100 of Figure 11 may be performed by an apparatus configured for wireless communication. For example, the apparatus may include at least one processor, and a memory coupled to the processor. The processor may be configured to perform operations of the process 1100 of Figure 11. In some other implementations, the process 1100 of Figure 11 may be performed or executed using a non-transitory computer-readable medium having program code recorded thereon. The program code may be program code executable by a computer for causing the computer to perform operations of the processes 1100 of Figure 11.

[00143] As illustrated at block 1102, the UE determines that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device. In some implementations, the unlicensed channel is included in an unlicensed spectrum the unlicensed spectrum includes 5.725-5.850 gigahertz (GHz), 5.850-5.925 GHz, or a combination thereof, or another spectrum that can be shared to V2X communication. The first device may include or correspond to the second UE 330, the third UE 340, or the network entity 350. In some implementations, the first frequency resource may be reserved by the first device after performance of a listen-before-talk (LBT) procedure by the first device.

[00144] At block 1104, the UE transmits a communication in a second frequency resource in the unlicensed channel in the first slot. The communication may include or correspond to the message 392. In some implementations, the communication includes a vehicle-to-everything (V2X) communication. As an illustrative, non-limiting example, the V2X communication may include a cellular (C)-V2X communication. In some implementations, the communication may be transmitted without performing a LBT procedure by the UE.

[00145] The second frequency may include a subchannel or a resource block of the unlicensed channel. In some implementations, the UE may select the second frequency resource in the first slot based on a random selection, a measurement of the second frequency in a slot prior to the first slot, or a combination thereof.

[00146] In some implementations of the process 1100, the UE may determine that the first frequency resource in the unlicensed channel is reserved in a second slot by the device. The second slot may be a next slot after the first slot. Additionally, or alternatively, the UE may transmit in the second frequency resource (in the unlicensed channel) in the second slot. In some implementations, the UE may also determine that a third resource in the unlicensed channel is reserved in the first slot by a second device that is distinct from the first device.

[00147] In some implementations, the UE may determine the second frequency resource is an unreserved resource in the first slot. Additionally, or alternatively, the communication may include an indicator to reserve the second frequency resource in a second slot is a next slot after the first slot. [00148] In some implementations, the UE may receive sidelink information from the first device. The sidelink information may include or correspond to the sidelink information 390 or the sidelink information 391. The sidelink information may indicate that the first frequency resource is reserved in the first slot. In some implementations, the sidelink information includes sidelink control information.

[00149] The UE may decode the sidelink information. For example, the UE may decode the sidelink information using the sidelink decoder 312. The UE may determine whether the first frequency is reserved is based on the decoded sidelink transmission. In some implementations, the UE may determine whether all frequency resources of the unlicensed channel are reserved in the first slot.

[00150] The UE may perform the sidelink decoding using the sidelink decoder 312. In some implementations, the UE may perform the energy detection based on a determination of the no sidelink transmission is decoded. To perform the energy detection, the UE may determine whether the unlicensed channel is available based on a clear channel assessment (CCA). For example, performing the energy detection may include performing the CCA with or without a back-off period. The back-off period may include a random back off period or a predetermine back off period, as illustrative, non-limiting examples.

[00151] The back-off period may be included within a contention window. During the contention window, the UE may perform the random back-off, and sense the unlicensed channel. If the unlicensed channel is free at the end of the contention window, the UE may access the unlicensed channel.

[00152] During the first slot, the UE may performing energy detection associated with listen- before-talk (LBT), performing sidelink decoding, or a combination thereof. The UE may perform the energy detection using the energy detector 310. To perform the energy detection, the UE may measure an energy associated with the unlicensed channel, and perform a comparison based on the measured energy and a threshold.

[00153] In some implementations, the UE may determine the unlicensed channel is busy based on a determination that the measured energy is greater than or equal to the threshold. Alternatively, the UE may determine the unlicensed channel is available based on a determination that the measured energy is less than or equal to the threshold. The UE may transmit sidelink information based on the determination that the measured energy is less than or equal to the threshold. The sidelink information transmitted by the UE may include a reservation indicator or sidelink control data. [00154] In some implementations, the UE may determine a COT of the device. The COT may correspond to the unlicensed channel. Access to the unlicensed channel by the UE may be based on the COT of the device. Alternatively, the UE may determine a channel occupancy time (COT) of the UE. Access to the unlicensed channel by the UE may be based on the COT ofthe UE.

[00155] In some implementations, the UE may determine whether priority traffic, such as high priority traffic, is pending for transmission. The UE may transmit the communication based a determination a determination that the high priority traffic is pending.

[00156] Thus, the process 1100 of Figure 11 enables the UE to access a channel in an unlicensed spectrum. By accessing the channel in the unlicensed spectrum as described herein, the UE may transmit a communication, such as a V2X message. Additionally, in some implementations, the UE may access an unlicensed without performing LBT. In some other implementations, the UE may access an available frequency resource of the channel while another UE concurrently access a different frequency resource of the channel.

[00157] It is noted that one or more blocks (or operations) described with reference to Figure 11 may be combined with one or more blocks (or operations) of another of figure. For example, one or more blocks (or operations) of Figure 11 may be combined with one or more blocks (or operations) of Figures 3-10.

[00158] Figure 12 is a block diagram conceptually illustrating a design of the UE 1200. The UE 1200 may include or correspond to UE 115, 330, 340, or a V2X entity. The UE 1200 may be configured to perform one or more operations to access a channel in an unlicensed spectrum, according to one aspect of the present disclosure. For example, the UE 1200 may access the channel to transmit a communication, such as a V2X message. The UE 1200 includes the structure, hardware, and components as illustrated for the UE 115 of Figures 2 or 3. For example, the UE 1200 includes the controller/processor 280, which operates to execute logic or computer instructions stored in the memory 282, as well as controlling the components of the UE 1200 that provide the features and functionality of the UE 1200. The UE 1200, under control of the controller/processor 280, transmits and receives signals via wireless radios 1201a-r and the antennas 252a-r. The wireless radios 1201a-r include various components and hardware, as illustrated in Figure 2 for the UE 115, including the modulator/demodulators 254a-r, the MIMO detector 256, the receive processor 258, the transmit processor 264, and the TX MIMO processor 266.

[00159] As shown, the memory 282 may include channel access information 1202, one or more thresholds 1203, energy detection logic 1204, sidelink decoding logic 1205, and timer logic 1206. The channel access information 1202 and the one or more thresholds 1002 may include or correspond to the channel access information 306 and the threshold 308, respectively. The energy detection logic 1204, the sidelink decoding logic 1205, and the timer logic may include or correspond to the energy detector 310, the sidelink decoder 312, and the timer 314, respectively. The UE 1200 may receive signals from or transmit signals to one or more network entities, one or more UEs 115, 330, 340, the base station 105, the network entity 350 of Figure 3, a core network, a core network device, a network entity as illustrated in Figure 13, a V2X entity, or a combination thereof. The UE 1200 may be configured to perform one or more operations described with reference to Figures 4-11.

[00160] Figure 13 is a block diagram conceptually illustrating a design of a network entity 1300. The network entity 1300 may include the base station 105, a network, or a core network, the network entity 350, as illustrative, non-limiting examples. The network entity 1300 includes the structure, hardware, and components as illustrated for the base station 105 of Figures 1 and 2, the network entity 350 of Figure 3, or a combination thereof. For example, the network entity 1300 may include the controller/processor 240, which operates to execute logic or computer instructions stored in the memory 242, as well as controlling the components of the network entity 1300 that provide the features and functionality of the network entity 1300. The network entity 1300, under control of the controller/processor 240, transmits and receives signals via wireless radios 1301a-t and the antennas 234a-t. The wireless radios 1301a-t include various components and hardware, as illustrated in Figure 2 for the network entity 350 (such as the base station 105), including the modulator/demodulators 232a-t, the transmit processor 220, the TX MIMO processor 230, the MIMO detector 236, and the receive processor 238.

[00161] As shown, the memory 242 may include message generation logic 1302, such as V2X message generation logic, and transmission logic 1303. The network entity 1300 may receive signals or message from or transmit signals or messages to one or more UEs, such as UE 115 of Figures 1-3, and one or more V2X entities, one or more other network entities, or a combination thereof. Additionally, or alternatively, the network entity 1300 may include energy detection logic, sidelink decoding logic, timer logic, or a combination thereof. The energy detection logic, the sidelink decoding logic, the timer logic, or a combination thereof, may be configured to perform one or more operations as described herein with reference to UE 1200 and Figure 12.

[00162] In some aspects, techniques for accessing a channel in an unlicensed spectrum may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes or devices described elsewhere herein. In some aspects, accessing a channel in an unlicensed spectrum may include an apparatus configured to determine that a first frequency resource in an unlicensed channel is reserved in a first slot by a first device, and transmit a communication in a second frequency resource in the unlicensed channel in the first slot. In some implementations, the apparatus includes a wireless device, such as a UE, a network entity, or V2X entity. In some implementations, the apparatus may include at least one processor, and a memory coupled to the processor. The processor may be configured to perform operations described herein with respect to the wireless device. In some other implementations, the apparatus may include a non-transitory computer-readable medium having program code recorded thereon and the program code may be executable by a computer for causing the computer to perform operations described herein with reference to the wireless device. In some implementations, the apparatus may include one or more means configured to perform operations described herein. In some implementations, operations described with reference to the apparatus may include a method for wireless communication.

[00163] In a first aspect, the communication includes a vehi cl e-to-every thing (V2X) communication or device-to-device communication.

[00164] In a second aspect, alone or in combination with the first aspect, the first device reserved the first frequency resource after performance of a listen-before-talk (LBT) procedure.

[00165] In a third aspect, alone or in combination with one or more of the first through second aspects, the apparatus determines that the first frequency resource in the unlicensed channel is reserved in a second slot by the device, the second slot is a next slot after the first slot.

[00166] In a fourth aspect, in combination with the third aspect, the apparatus transmits in the second frequency resource in the unlicensed channel in the second slot.

[00167] In a fifth aspect, in combination with the fourth aspects, the apparatus determines that a third resource in the unlicensed channel is reserved in the first slot by a second device.

[00168] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the communication is transmitted without performing a listen-before-talk (LBT) procedure.

[00169] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the unlicensed channel is included in an unlicensed spectrum.

[00170] In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the apparatus receives sidelink information from the first device. [00171] In a ninth aspect, in combination with the eighth aspect, the sidelink information indicates that the first frequency resource is reserved in the first slot.

[00172] In a tenth aspect, in combination with the ninth aspects, the apparatus decodes the sidelink information, and wherein the sidelink information includes sidelink control information.

[00173] In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the apparatus determines the second frequency resource is available.

[00174] In a twelfth aspect, in combination with the eleventh aspect, the apparatus reserves the second frequency resource in a second slot that is a next slot after the first slot.

[00175] In a thirteenth aspect, in combination with the twelfth aspect, the apparatus determines the second frequency resource is an unreserved resource in the first slot.

[00176] In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the apparatus determines that a sidelink transmission is decoded based on performing the sidelink decoding.

[00177] In a fifteenth aspect, in combination with the fourteenth aspect, determining the first frequency is reserved is based on the decoded sidelink transmission.

[00178] In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspect, the apparatus determines whether all frequency resources of the a first frequency resource are reserved in the first slot.

[00179] In a seventeenth aspect, in combination with one or more of the eleventh through sixteenth aspects, the second frequency includes a subchannel or a resource block of the unlicensed channel.

[00180] In an eighteenth aspect, in combination with the seventeenth aspect, the apparatus selects the second frequency resource in the first slot based on a random selection, a measurement of the second frequency in a slot prior to the first slot, or a combination thereof.

[00181] In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, the apparatus, during the first slot, performs energy detection associated with listen-before-talk (LBT); and.

[00182] In a twentieth aspect, in combination with the nineteenth aspect, the apparatus, during the first slot, performs sidelink decoding.

[00183] In a twenty-first aspect, in combination with the nineteenth through twentieth aspects, the apparatus determines that no sidelink transmission is decoded based on performing the sidelink decoding. [00184] In a twenty-second aspect, in combination with the twenty-first aspect, the energy detection is performed based on a determination of the no sidelink transmission being decoded.

[00185] In a twenty-third aspect, in combination with one or more of the nineteenth through twenty-second aspects, to perform the energy detection, the apparatus determines whether the unlicensed channel is available based on a clear channel assessment (CCA).

[00186] In a twenty-fourth aspect, in combination with the twenty-third aspect, to perform the energy detection, the apparatus performs the CCA with or without a back-off period.

[00187] In a twenty-fifth aspect, in combination with the twenty-fourth aspect, the back-off period includes a random back off period.

[00188] In a twenty-sixth aspect, in combination with one or more of the nineteenth through twenty-fifth aspects, to perform the energy detection, the apparatus measures an energy associated with the unlicensed channel.

[00189] In a twenty-seventh aspect, in combination with the twenty-sixth aspect, to perform the energy detection, the apparatus performs a comparison based on the measured energy and a threshold.

[00190] In a twenty-eighth aspect, alone or in combination with one or more of the twenty- sixth through twenty-seventh aspects, the apparatus determines the unlicensed channel is busy based on a determination that the measured energy is greater than or equal to the threshold..

[00191] In a twenty-ninth aspect, in combination with one or more of the twenty-fourth through twenty-fifth aspects, the back-off period is included within a contention window.

[00192] In a thirtieth aspect, in combination with the twenty-sixth through twenty-seventh aspects , the apparatus determines the unlicensed channel is available based on a determination that the measured energy is less than or equal to the threshold.

[00193] In a thirty-first aspect, in combination with the thirtieth aspects, the apparatus transmits sidelink information based on the determination that the measured energy is less than or equal to the threshold.

[00194] In a thirty-second aspect, in combination with one or more twenty-sixth through twenty-seventh aspects, the apparatus, during a contention window: performs a random back off and senses the unlicensed channel.

[00195] In a thirty-third aspect, in combination with the thirty-second aspect, if the unlicensed channel is free at the end of the contention window, the apparatus accesses the unlicensed channel. [00196] In a thirty-fourth aspect, alone or in combination with one or more of the first through thirty-fourth aspects, the apparatus determines a channel occupancy time (COT) of the device, the COT corresponding to the unlicensed channel; and.

[00197] In a thirty-fifth aspect, in combination with the thirty-third aspect, access to the unlicensed channel by the apparatus is based on the COT.

[00198] In a thirty-sixth aspect, alone or in combination with one or more of the first through thirty-fifth aspects, the apparatus determines whether high priority traffic is pending for transmission.

[00199] In a thirty-seventh aspect, in combination with the thirty-sixth aspect, transmitting the communication is based a determination a determination that the high priority traffic is pending.

[00200] Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[00201] Components, the functional blocks, and the modules described herein with respect to Figures 1-13 include processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof. In addition, features discussed herein may be implemented via specialized processor circuitry, via executable instructions, or combinations thereof.

[00202] Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Skilled artisans will also readily recognize that the order or combination of components, methods, or interactions that are described herein are merely examples and that the components, methods, or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those illustrated and described herein.

[00203] The various illustrative logics, logical blocks, modules, circuits and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.

[00204] The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. In some implementations, a processor may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes and methods may be performed by circuitry that is specific to a given function.

[00205] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Implementations of the subject matter described in this specification also can be implemented as one or more computer programs, that is one or more modules of computer program instructions, encoded on a computer storage media for execution by, or to control the operation of, data processing apparatus

[00206] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The processes of a method or algorithm disclosed herein may be implemented in a processor-executable software module which may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program from one place to another. A storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection can be properly termed a computer-readable medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu- ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine readable medium and computer-readable medium, which may be incorporated into a computer program product.

[00207] Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to some other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

[00208] Additionally, a person having ordinary skill in the art will readily appreciate, the terms “upper” and “lower” are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of any device as implemented.

[00209] Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. [00210] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, some other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.

[00211] As used herein, including in the claims, the term “or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of’ indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (that is A and B and C) or any of these in any combination thereof. The term “substantially” is defined as largely but not necessarily wholly what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. In any disclosed implementations, the term “substantially” may be substituted with “within [a percentage] of’ what is specified, where the percentage includes .1, 1, 5, or 10 percent.

[00212] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.