Patent Publication Number: US-2021195577-A1

Title: Facilitating device-to-device communications

Description:
PRIORITY CLAIM 
     This application claims priority to and the benefit of provisional patent application No. 62/951,885 filed in the U.S. Patent and Trademark Office on Dec. 20, 2019, the entire content of which is incorporated herein by reference as if fully set forth below in its entirety and for all applicable purposes. 
    
    
     TECHNICAL FIELD 
     The technology discussed below relates generally to wireless communication systems, and more particularly, to facilitating device-to-device communications. 
     INTRODUCTION 
     Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be accessed by various types of devices adapted to facilitate wireless communications, where multiple devices share the available system resources (e.g., time, frequency, and power). 
     Fifth generation (5G) New Radio (NR) networks may exhibit a higher degree of flexibility and scalability than fourth generation (4G) Long Term Evolution (LTE) networks, and are envisioned to support very diverse sets of requirements. Techniques applicable in such 5G NR networks for reducing power consumption and improving battery life, as well as facilitating device-to-device communications may be desirable. 
     BRIEF SUMMARY OF SOME EXAMPLES 
     The following presents a summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. 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 a form as a prelude to the more detailed description that is presented later. 
     Various examples and implementations of the present disclosure facilitate device-to-device communications as well as reduced power consumption in wireless communication devices operating in wireless communications systems. In at least one aspect of the present disclosure, wireless communication devices are provided. In at least one example, a wireless communication device may include a transceiver and a processing circuit coupled to the transceiver. The processing circuit may be configured to transmit via the transceiver a reservation signal to reserve one or more sidelink resources for use by another device, and receive via the transceiver a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources. 
     In at least one example, a wireless communication device may include a transceiver and a processing circuit coupled to the transceiver. The processing circuit may be configured to detect via the transceiver a reservation signal from another device, wherein the reservation signal is configured to reserve one or more sidelink resources, and transmit via the transceiver a sidelink transmission on at least a portion of the one or more of the sidelink resources reserved by the other device. 
     Further aspects provide methods of wireless communication and/or apparatus for wireless communication including means to perform such methods. One or more examples of such methods may include transmitting a reservation signal to reserve one or more sidelink resources for use by another device, and receiving a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources. 
     One or more further examples of such methods may include detecting a reservation signal from another device, wherein the reservation signal is configured to reserve one or more sidelink resources, and transmitting a sidelink transmission on the one or more of the sidelink resources reserved by the other device. 
     These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain embodiments and figures below, all embodiments of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the invention discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an example of a wireless communication system according to one or more embodiments. 
         FIG. 2  is a conceptual diagram illustrating an example of a radio access network according to some embodiments. 
         FIG. 3  is a diagram illustrating an example of a wireless communication network employing sidelink communication according to some aspects. 
         FIG. 4  is a schematic diagram illustrating organization of wireless resources in an air interface utilizing orthogonal frequency divisional multiplexing (OFDM). 
         FIG. 5  is a flow diagram depicting communications between two UEs, including at least one power-sensitive UE according to one or more embodiments. 
         FIG. 6  is a flow diagram depicting communications between two UE-A and UE-B, where UE-A is a power-sensitive device and UE-B is not a power-sensitive device according to some embodiments. 
         FIG. 7  is a flow diagram depicting communications between UE-A and UE-B, where UE-B is a power-sensitive device and UE-A is not a power-sensitive device according to some embodiments. 
         FIG. 8  is a block diagram illustrating select components of a wireless communication device employing a processing system according to at least one example of the present disclosure. 
         FIG. 9  is a flow diagram illustrating a wireless communication method (e.g., operational on or via a wireless communication device) according to some embodiments. 
         FIG. 10  is a flow diagram illustrating a wireless communication method (e.g., operational on or via a wireless communication device) according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     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 represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form to avoid obscuring such concepts. 
     While aspects and embodiments are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, embodiments and/or uses may come about via integrated chip embodiments and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc.). 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 a spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice of claimed and described embodiments. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor(s), interleaver, adders/summers, etc.). It is intended that innovations described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, etc. of varying sizes, shapes, and constitution. 
     The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. Referring now to  FIG. 1 , as an illustrative example without limitation, various aspects of the present disclosure are illustrated with reference to a wireless communication system  100 . The wireless communication system  100  includes three interacting domains: a core network  102 , a radio access network (RAN)  104 , and a user equipment (UE)  106 . By virtue of the wireless communication system  100 , the UE  106  may be enabled to carry out data communication with an external data network  110 , such as (but not limited to) the Internet. 
     The RAN  104  may implement any suitable wireless communication technology or technologies to provide radio access to the UE  106 . As one example, the RAN  104  may operate according to 3 rd  Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN  104  may operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as LTE. The 3GPP refers to this hybrid RAN as a next-generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure. 
     As illustrated, the RAN  104  includes a plurality of base stations  108 . Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. In different technologies, standards, or contexts, a base station may variously be referred to by those skilled in the art as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable terminology. In some examples, a base station may include two or more TRPs that may be collocated or non-collocated. Each TRP may communicate on the same or different carrier frequency within the same or different frequency band. 
     The radio access network  104  is further illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus may be referred to as user equipment (UE) in 3GPP standards, but 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, or some other suitable terminology. A UE may be an apparatus that provides a user with access to network services. 
     Within the present document, a “mobile” apparatus need not necessarily have a capability to move, and may be stationary. The term mobile apparatus or mobile device broadly refers to a diverse array of devices and technologies. UEs may include a number of hardware structural components sized, shaped, and arranged to help in communication; such components can include antennas, antenna arrays, RF chains, amplifiers, one or more processors, etc. electrically coupled to each other. For example, some non-limiting examples of a mobile apparatus include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC), a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA), and a broad array of embedded systems, e.g., corresponding to an “Internet of things” (IoT). A mobile apparatus may additionally be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotics device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and/or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, etc. A mobile apparatus may additionally be a digital home or smart home device such as a home audio, video, and/or multimedia device, an appliance, a vending machine, intelligent lighting, a home security system, a smart meter, etc. A mobile apparatus may additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling electric power (e.g., a smart grid), lighting, water, etc., an industrial automation and enterprise device, a logistics controller, agricultural equipment, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, e.g., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be given preferential treatment or prioritized access over other types of information, e.g., in terms of prioritized access for transport of critical service data, and/or relevant QoS for transport of critical service data. 
     Wireless communication between a RAN  104  and a UE  106  may be described as utilizing an air interface. Transmissions over the air interface from a base station (e.g., base station  108 ) to one or more UEs (e.g., UE  106 ) may be referred to as downlink (DL) transmission. In accordance with certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station  108 ). Another way to describe this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE  106 ) to a base station (e.g., base station  108 ) may be referred to as uplink (UL) transmissions. In accordance with further aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at a scheduled entity (described further below; e.g., UE  106 ). 
     In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station  108 ) allocates resources for communication among some or all devices and equipment within its service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities. That is, for scheduled communication, UEs  106 , which may be scheduled entities, may utilize resources allocated by the scheduling entity  108 . 
     Base stations  108  are not the only entities that may function as scheduling entities. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). 
     As illustrated in  FIG. 1 , a scheduling entity  108  may broadcast downlink traffic  112  to one or more scheduled entities  106 . Broadly, the scheduling entity  108  is a node or device responsible for scheduling traffic in a wireless communication network, including the downlink traffic  112  and, in some examples, uplink traffic  116  from one or more scheduled entities  106  to the scheduling entity  108 . On the other hand, the scheduled entity  106  is a node or device that receives downlink control information  114 , including but not limited to scheduling information (e.g., a grant), synchronization or timing information, or other control information from another entity in the wireless communication network such as the scheduling entity  108 . 
     In general, base stations  108  may include a backhaul interface for communication with a backhaul portion  120  of the wireless communication system. The backhaul  120  may provide a link between a base station  108  and the core network  102 . Further, in some examples, a backhaul network may provide interconnection between the respective base stations  108 . Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network. 
     The core network  102  may be a part of the wireless communication system  100 , and may be independent of the radio access technology used in the RAN  104 . In some examples, the core network  102  may be configured according to 5G standards (e.g., 5GC). In other examples, the core network  102  may be configured according to a 4G evolved packet core (EPC), or any other suitable standard or configuration. 
     In some examples, scheduled entities such as a first scheduled entity  106  and a second scheduled entity  107  may utilize sidelink signals for direct device-to-device (D2D) communication. Sidelink signals may include sidelink traffic  122  and sidelink control  124 . Sidelink control information  124  may in some examples include a request signal, such as a request-to-send (RTS), a source transmit signal (STS), and/or a direction selection signal (DSS). The request signal may provide for a scheduled entity  106  to request a duration of time to keep a sidelink channel available for a sidelink signal. Sidelink control information  124  may further include a response signal, such as a clear-to-send (CTS) and/or a destination receive signal (DRS). The response signal may provide for the scheduled entity  106  to indicate the availability of the sidelink channel, e.g., for a requested duration of time. An exchange of request and response signals (e.g., handshake) may enable different scheduled entities performing sidelink communications to negotiate the availability of the sidelink channel prior to communication of the sidelink traffic information  122 . 
     Referring now to  FIG. 2 , by way of example and without limitation, a schematic illustration of a RAN  200  is provided. In some examples, the RAN  200  may be the same as the RAN  104  described above and illustrated in  FIG. 1 . The geographic area covered by the RAN  200  may be divided into cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on an identification broadcasted from one access point or base station.  FIG. 2  illustrates macrocells  202 ,  204 , and  206 , and a small cell  208 , each of which may include one or more sectors (not shown). A sector is a sub-area of a cell. All sectors within one cell are served by the same base station. A radio link within a sector can be identified by a single logical identification belonging to that sector. In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. 
     In  FIG. 2 , two base stations  210  and  212  are shown in cells  202  and  204 , and a third base station  214  is shown controlling a remote radio head (RRH)  216  in cell  206 . That is, a base station can have an integrated antenna or can be connected to an antenna or RRH by feeder cables. In the illustrated example, the cells  202 ,  204 , and  206  may be referred to as macrocells, as the base stations  210 ,  212 , and  214  support cells having a large size. Further, a base station  218  is shown in the small cell  208  (e.g., a microcell, picocell, femtocell, home base station, home Node B, home eNode B, etc.) which may overlap with one or more macrocells. In this example, the cell  208  may be referred to as a small cell, as the base station  218  supports a cell having a relatively small size. Cell sizing can be done according to system design as well as component constraints. 
     It is to be understood that the radio access network  200  may include any number of wireless base stations and cells. Further, a relay node may be deployed to extend the size or coverage area of a given cell. The base stations  210 ,  212 ,  214 ,  218  provide wireless access points to a core network for any number of mobile apparatuses. In some examples, the base stations  210 ,  212 ,  214 , and/or  218  may be the same as the base station/scheduling entity  108  described above and illustrated in  FIG. 1 . 
       FIG. 2  further includes a quadcopter or drone  220 , which may be configured to function as a base station. That is, in some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station such as the quadcopter  220 . 
     Within the RAN  200 , the cells may include UEs that may be in communication with one or more sectors of each cell. Further, each base station  210 ,  212 ,  214 ,  218 , and  220  may be configured to provide an access point to a core network  102  (see  FIG. 1 ) for all the UEs in the respective cells. For example, UEs  222  and  224  may be in communication with base station  210 , UEs  226  and  228  may be in communication with base station  212 , UEs  230  and  232  may be in communication with base station  214  by way of RRH  216 , UE  234  may be in communication with base station  218 , and UE  236  may be in communication with mobile base station  220 . In some examples, the UEs  222 ,  224 ,  226 ,  228 ,  230 ,  232 ,  234 ,  236 ,  238 ,  240 , and/or  242  may be the same as the UE/scheduled entity  106  described above and illustrated in  FIG. 1 . 
     In some examples, a mobile network node (e.g., quadcopter  220 ) may be configured to function as a UE. For example, the quadcopter  220  may operate within cell  202  by communicating with base station  210 . 
     In a further aspect of the RAN  200 , as noted with reference to  FIG. 1  above, sidelink signals may be used between UEs without necessarily relying on communications with a base station. For example, two or more UEs (e.g., UEs  226  and  228 ) may communicate with each other using peer to peer (P2P) or sidelink signals  227  without relaying that communication through a base station (e.g., base station  212 ). In a further example, UE  238  is illustrated communicating with UEs  240  and  242 . Here, the UE  238  may function as a scheduling entity or a primary sidelink device, and UEs  240  and  242  may function as a scheduled entity or a non-primary (e.g., secondary) sidelink device. In still another example, a UE may function as a scheduling entity in a D2D, peer-to-peer (P2P), or vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X), a mesh network, or other suitable direct link network. In a mesh network example, UEs  240  and  242  may optionally communicate directly with one another in addition to communicating with the scheduling entity  238 . Thus, in a wireless communication system with scheduled access to time-frequency resources and having a cellular configuration, a P2P/D2D configuration, or a mesh configuration, a scheduling entity and one or more scheduled entities may communicate utilizing the scheduled resources. 
     Two primary technologies that may be used by V2X networks include dedicated short range communication (DSRC) based on IEEE 802.11p standards and cellular V2X based on LTE and/or 5G (New Radio) standards. Various aspects of the present disclosure may relate to New Radio (NR) cellular V2X networks, referred to herein as V2X networks, for simplicity. However, it should be understood that the concepts disclosed herein may not be limited to a particular V2X standard or may be directed to sidelink networks other than V2X networks. 
       FIG. 3  illustrates an example of a wireless communication network  300  configured to support D2D or sidelink communication. In some examples, sidelink communication may include V2X communication. V2X communication involves the wireless exchange of information directly between not only vehicles (e.g., vehicles  302  and  304 ) themselves, but also directly between vehicles  302 / 304  and infrastructure (e.g., roadside units (RSUs)  306 ), such as streetlights, buildings, traffic cameras, tollbooths or other stationary objects, vehicles  302 / 304  and pedestrians  308 , and vehicles  302 / 304  and wireless communication networks (e.g., base station  310 ). In some examples, V2X communication may be implemented in accordance with the New Radio (NR) cellular V2X standard defined by 3GPP, Release 16, or other suitable standard. 
     V2X communication enables vehicles  302  and  304  to obtain information related to the weather, nearby accidents, road conditions, activities of nearby vehicles and pedestrians, objects nearby the vehicle, and other pertinent information that may be utilized to improve the vehicle driving experience and increase vehicle safety. For example, such V2X data may enable autonomous driving and improve road safety and traffic efficiency. For example, the exchanged V2X data may be utilized by a V2X connected vehicle  302  and  304  to provide in-vehicle collision warnings, road hazard warnings, approaching emergency vehicle warnings, pre-/post-crash warnings and information, emergency brake warnings, traffic jam ahead warnings, lane change warnings, intelligent navigation services, and other similar information. In addition, V2X data received by a V2X connected mobile device of a pedestrian/cyclist  308  may be utilized to trigger a warning sound, vibration, flashing light, etc., in case of imminent danger. 
     The sidelink communication between vehicle-UEs (V-UEs)  302  and  304  or between a V-UE  302  or  304  and either an RSU  3206  or a pedestrian-UE (P-UE)  308  may occur over a sidelink  312  utilizing a proximity service (ProSe) PC5 interface. In various aspects of the disclosure, the PC5 interface may further be utilized to support D2D sidelink  312  communication in other proximity use cases. Examples of other proximity use cases may include public safety or commercial (e.g., entertainment, education, office, medical, and/or interactive) based proximity services. In the example shown in  FIG. 3 , ProSe communication may further occur between UEs  314  and  316 . 
     ProSe communication may support different operational scenarios, such as in-coverage, out-of-coverage, and partial coverage. Out-of-coverage refers to a scenario in which UEs (e.g., V-UEs  302  and  304  and P-UE  3208 ) are outside of the coverage area of a base station (e.g., base station  310 ), but each are still configured for ProSe communication. Partial coverage refers to a scenario in which some of the UEs (e.g., V-UE  304 ) are outside of the coverage area of the base station  310 , while other UEs (e.g., V-UE  302  and P-UE  308 ) are in communication with the base station  310 . In-coverage refers to a scenario in which UEs (e.g., UEs  314  and  316 ) are in communication with the base station  310  (e.g., gNB) via a Uu (e.g., cellular interface) connection to receive ProSe service authorization and provisioning information to support ProSe operations. 
     To facilitate D2D sidelink communication between, for example, UEs  314  and  316  over the sidelink  312 , the UEs  314  and  316  may transmit discovery signals therebetween. In some examples, each discovery signal may include a synchronization signal, such as a primary synchronization signal (PSS) and/or a secondary synchronization signal (SSS) that facilitates device discovery and enables synchronization of communication on the sidelink  312 . For example, the discovery signal may be utilized by the UE  316  to measure the signal strength and channel status of a potential sidelink (e.g., sidelink  312 ) with another UE (e.g., UE  314 ). The UE  316  may utilize the measurement results to select a UE (e.g., UE  314 ) for sidelink communication or relay communication. 
     In 5G NR sidelink, sidelink communication may utilize transmission or reception resource pools. For example, the minimum resource allocation unit in frequency may be a sub-channel (e.g., which may include, for example, 10, 15, 20, 25, 50, 75, or 100 consecutive resource blocks) and the minimum resource allocation unit in time may be one slot. A radio resource control (RRC) configuration of the resource pools may be either pre-configured (e.g., a factory setting on the UE determined, for example, by sidelink standards or specifications) or configured by a base station (e.g., base station  310 ). 
     In addition, there may be two main resource allocation modes of operation for sidelink (e.g., PC5) communications. In a first mode, Mode 1, a base station (e.g., gNB)  310  may allocate resources to sidelink devices (e.g., V2X devices or other sidelink devices) for sidelink communication between the sidelink devices in various manners. For example, the base station  310  may allocate sidelink resources dynamically (e.g., a dynamic grant) to sidelink devices, in response to requests for sidelink resources from the sidelink devices. The base station  310  may further activate preconfigured sidelink grants (e.g., configured grants) for sidelink communication among the sidelink devices. In Mode 1, sidelink feedback may be reported back to the base station  310  by a transmitting sidelink device. 
     In a second mode, Mode 2, the sidelink devices may autonomously select sidelink resources for sidelink communication therebetween. In some examples, a transmitting sidelink device may perform resource/channel sensing to select resources (e.g., sub-channels) on the sidelink channel that are unoccupied. Signaling on the sidelink  312  is the same between the two modes. Therefore, from a receiver&#39;s point of view, there is no difference between the modes. 
     Various aspects of the present disclosure will be described with reference to an OFDM waveform, schematically illustrated in  FIG. 4 . It should be understood by those of ordinary skill in the art that the various aspects of the present disclosure may be applied to an SC-FDMA waveform in substantially the same way as described herein below. That is, while some examples of the present disclosure may focus on an OFDM link for clarity, it should be understood that the same principles may be applied as well to SC-FDMA waveforms. 
     Referring now to  FIG. 4 , an expanded view of an exemplary DL subframe  402  is illustrated, showing an OFDM resource grid  404 . However, as those skilled in the art will readily appreciate, the PHY transmission structure for any particular application may vary from the example described here, depending on any number of factors. Here, time is in the horizontal direction with units of OFDM symbols, and frequency is in the vertical direction with units of subcarriers or tones. 
     The resource grid  404  may be used to schematically represent time-frequency resources for a given antenna port. That is, in a multiple-input-multiple-output (MIMO) implementation with multiple antenna ports available, a corresponding multiple number of resource grids  404  may be available for communication. The resource grid  404  is divided into multiple resource elements (REs)  406 . An RE, which is 1 subcarrier x  1  symbol, is the smallest discrete part of the time-frequency grid, and contains a single complex value representing data from a physical channel or signal. Depending on the modulation utilized in a particular implementation, each RE may represent one or more bits of information. In some examples, a block of REs may be referred to as a physical resource block (PRB) or more simply a resource block (RB)  408 , which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers, a number independent of the numerology used. In some examples, depending on the numerology, an RB may include any suitable number of consecutive OFDM symbols in the time domain. Within the present disclosure, it is assumed that a single RB such as the RB  408  entirely corresponds to a single direction of communication (either transmission or reception for a given device). 
     Scheduling of UEs or sidelink devices (hereinafter collectively referred to as UEs) for downlink, uplink, or sidelink transmissions typically involves scheduling one or more resource elements  306  within one or more sub-bands. Thus, a UE generally utilizes only a subset of the resource grid  304 . In some examples, an RB may be the smallest unit of resources that can be allocated to a UE. Thus, the more RBs scheduled for a UE, and the higher the modulation scheme chosen for the air interface, the higher the data rate for the UE. The RBs may be scheduled by a base station (e.g., gNB, eNB, etc.) or may be self-scheduled by a UE/sidelink device implementing D2D sidelink communication. 
     In this illustration, the RB  408  is shown as occupying less than the entire bandwidth of the subframe  402 , with some subcarriers illustrated above and below the RB  408 . In a given implementation, the subframe  402  may have a bandwidth corresponding to any number of one or more RBs  408 . Further, in this illustration, the RB  408  is shown as occupying less than the entire duration of the subframe  402 , although this is merely one possible example. 
     Each subframe  402  (e.g., a 1 ms subframe) may consist of one or multiple adjacent slots. In the example shown in  FIG. 4 , one subframe  402  includes four slots  410 , as an illustrative example. In some examples, a slot may be defined according to a specified number of OFDM symbols with a given cyclic prefix (CP) length. For example, a slot may include 7 or 14 OFDM symbols with a nominal CP. Additional examples may include mini-slots having a shorter duration (e.g., 1, 2, 4, or 7 OFDM symbols). These mini-slots may in some cases be transmitted occupying resources scheduled for ongoing slot transmissions for the same or for different UEs. 
     An expanded view of one of the slots  410  illustrates the slot  410  including a control region  412  and a data region  414 . In general, the control region  412  may carry control channels (e.g., PDCCH), and the data region  414  may carry data channels (e.g., PDSCH or PUSCH). Of course, a slot may contain all DL, all UL, or at least one DL portion and at least one UL portion. The simple structure illustrated in  FIG. 4  is merely exemplary in nature, and different slot structures may be utilized, and may include one or more of each of the control region(s) and data region(s). 
     Although not illustrated in  FIG. 4 , the various REs  406  within a RB  408  may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs  406  within the RB  408  may also carry pilots or reference signals. These pilots or reference signals may provide for a receiving device to perform channel estimation of the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within the RB  408 . 
     In a DL transmission, the scheduling entity may allocate one or more REs  406  (e.g., within a control region  412 ) to carry DL control information including one or more DL control channels that generally carry information originating from higher layers, such as a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), etc., to one or more scheduled entities. In addition, DL REs may be allocated to carry DL physical signals that generally do not carry information originating from higher layers. These DL physical signals may include a primary synchronization signal (PSS); a secondary synchronization signal (SSS); demodulation reference signals (DM-RS); phase-tracking reference signals (PT-RS); channel-state information reference signals (CSI-RS); etc. 
     In an UL transmission, a transmitting device (e.g., a scheduled entity  106 ) may utilize one or more REs  406  to carry UL control information  118  (UCI). The UCI can originate from higher layers via one or more UL control channels, such as a physical uplink control channel (PUCCH), a physical random access channel (PRACH), etc., to the scheduling entity  108 . In addition to control information, one or more REs  406  (e.g., within the data region  414 ) may be allocated for user data or traffic data. Such traffic may be carried on one or more traffic channels, such as, for a DL transmission, a physical downlink shared channel (PDSCH); or for an UL transmission, a physical uplink shared channel (PUSCH). 
     The channels or carriers described above and illustrated in  FIGS. 1 and 4  are not necessarily all the channels or carriers that may be utilized between a scheduling entity  108  and scheduled entities  106 , and those of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels. 
     These physical channels described above are generally multiplexed and mapped to transport channels for handling at the medium access control (MAC) layer. Transport channels carry blocks of information called transport blocks (TB). The transport block size (TBS), which may correspond to a number of bits of information, may be a controlled parameter, based on the modulation and coding scheme (MCS) and the number of RBs in a given transmission. 
     In sidelink communications, resource allocation may be autonomous. Autonomous resource allocation refers to the UEs participating in sidelink communications determine time and frequency resources for data transmissions without scheduling by a network entity (e.g. base station). In some instances, a UE involved in sidelink communications may be power sensitive, such as when a UE operates on a limited power source (e.g., a battery). It may not be beneficial for a power-sensitive UE to continuously monitor sidelink transmissions to receive any relevant transmissions. According to one or more aspects of the present disclosure, UEs may be adapted to facilitate resource allocation for another UE in sidelink communications. In some implementations, such resource allocation for sidelink communications may facilitate power savings in one or more wireless communication devices. By way of example and not limitation, the various aspects of the present disclosure may find application in communications between a pedestrian UE (P-UE) and a vehicle UE (V-UE), where the P-UE is the power-sensitive device and the V-UE is not power sensitive. 
     According to one or more aspects of the present disclosure, a first UE reserves sidelink resources for a second UE. For example,  FIG. 5  is a flow diagram depicting communications between two UEs, a first UE (UE-A)  502 , and a second UE (UE-B)  504 . As indicated, UE-A  502  may reserve  506  sidelink resource(s) for UE-B  504 . UE-B  504  can determine  508  which resource(s) is/are reserved, and may send sidelink traffic  510  on at least a portion of the reserved sidelink resource(s). In this example, the sidelink traffic  510  is shown as being sent by the UE-B  504  to the UE-A  502 , but it should be understood that the UE-B  504  may use the resource reservation for sending a sidelink transmission to a different UE from UE-A  502 . 
     In some embodiments of  FIG. 5 , the UE-A may be a power-sensitive device.  FIG. 6  is a flow diagram depicting communications between UE-A  602  and UE-B  604 , where UE-A  602  is a power-sensitive device and UE-B  604  is not a power-sensitive device. By way of example and not limitation, UE-A  602  may be a P-UE and UE-B  604  may be a V-UE, where the UEs are participating in vehicle-to-pedestrian (V2P) communications. This example is only illustrative, and should not be limiting to the present disclosure. It should be apparent that UE-A  602  and UE-B  604  may also be other types of UEs according to various examples. 
     As depicted, the UE-A  602  may optionally sense the sidelink resource pool  606  to determine resource usage. Based on such sensing of the sidelink resource pool, the UE-A  602  can learn whether time/frequency resources have been or will be occupied by other devices. The UE-A  602  can accordingly select a sidelink resource to be utilized by UE-B  604 . In other implementations, the UE-A  602  may simply randomly select one or more random sidelink resources. With a sidelink resource(s) selected, the UE-A  602  can transmit  608  a sidelink data transmission together with signaling configured to reserve the one or more sidelink resources for a future sidelink transmission from UE-B  604 . In at least one embodiment, the sidelink data transmission may include a pedestrian safety message (PSM). 
     The UE-B  604  can detect the resource reservation signaling to determine which resource(s)  610  are reserved, and can transmit sidelink traffic  612  in at least a portion of the resource(s) indicated by the reservation signaling. The resource reservation may reserve a single sidelink resource for the UE-B transmission in some implementations, or may reserve multiple sidelink resources for the UE-B  604  to select from for the sidelink traffic transmission  612 . 
     By reserving one or more sidelink resources for UE-B  604  to utilize, the UE-A  602  knows where to receive any response message from UE-B  604 . Accordingly, the UE-A  602  can power down one or more components outside of the reserved sidelink resource(s) to achieve power savings. 
     In some embodiments of  FIG. 5 , the UE-B may be a power-sensitive device.  FIG. 7  is a flow diagram depicting communications between UE-A  702  and UE-B  704 , where UE-B  704  is a power-sensitive device and UE-A  702  is not a power-sensitive device. By way of example and not limitation, UE-A  702  may be a V-UE and UE-B  704  may be a P-UE, where the UEs are participating in vehicle-to-pedestrian (V2P) communications. In other examples, UE-A  702  may be a smartphone and UE-B  704  may be a wearable device, such that the UE-B  704  may be more power sensitive than UE-A  702 , even though both UEs may operate with a limited power source. These examples are only illustrative, and should not be limiting to the present disclosure. It should be apparent that UE-A  702  and UE-B  704  may also be other types of UEs according to various examples. 
     In some examples, the UE-B  704  may send a sidelink transmission and/or a sidelink resource request  706 . For example, the UE-B  704  may send a data transmission and/or a scheduling request that is received by UE-A  702 . In other embodiments, the UE-A  702  may simply reserve resources for other UEs (e.g., UE-B  704 ) in a periodical manner, without necessarily receiving any sidelink transmission and/or sidelink resource request. 
     In response to receiving the sidelink transmission and/or resource request, the UE-A  702  may select one or more sidelink resources for the UE-B  704  to use in a future sidelink transmission. According to at least one example, such selection may include an optional sensing of the sidelink resource pool  708  by the UE-A  702  to identify sidelink resources that may be available in the future. In other examples, the UE-B  704  may simply select one or more sidelink resources randomly to be reserved. 
     After sending the sidelink traffic and/or resource request, the UE-B  704  can monitor  710  the sidelink resource reservation signaling. After selecting one or more sidelink resources, the UE-A  702  can send sidelink resource reservation signaling  712 , which may be detected by the UE-B  704 . After detecting the resource reservation signaling, the UE-B  704  determines  714  which sidelink resource(s) is/are reserved, and may send sidelink traffic  716  on at least a portion of the reserved sidelink resource(s). 
     In some examples, the resource reservation may include a single sidelink resource. In other examples, the resource reservation may include multiple reservations, including resources for multiple transmission occasions, e.g., the reserved resources are resources in multiple slots and/or multiple resource blocks (RBs)/subchannels. In examples where the UE-A  702  reserved multiple resources, the UE-B  704  may transmit in each of the multiple resources, such as by repeating the sidelink transmission or by sending different packets in each of the multiple reserved sidelink resources. In another example where the UE-A  702  reserved multiple resources, the UE-B  704  may transmit in one of the multiple resources, where the resource used for transmission is determined by some pre-defined rule, e.g., randomly select one of the reserved resource, or select a resource implied by an ID of UE-B, etc. 
     In some examples, the UE-B  704  may indicate its location in the sidelink transmission and/or sidelink resource request  706 . Such a location indicator may be used by any receiving UE, such as UE-A  702 , to determine whether or not to reserve sidelink resources for the UE-B  704 . For example, the receiving UEs may utilize a range threshold, where any UE outside of the range threshold (e.g., more than a threshold distance from the UE-B  704 ) is configured to not reserve any sidelink resources for the UE-B  704 . 
     In some examples, more than one UE may receive the sidelink traffic and/or resource request  706  from the UE-B  704 . In embodiments that utilize the location indicator, more than one UE may receive the transmission  706  and may also be within the range threshold. As a result, more than one UE may reserve a sidelink resource for UE-B  704 . In such examples, the UE-B  704  may select one of the reserved sidelink resources for use in transmitting. Alternatively, the UE-B  704  may transmit in more than one or all of the reserved resources, such as in a repetition manner. 
     By enabling the UE-A  702  to reserve sidelink resources for UE-B  704  in this example, the UE-B  704  can conserve power by avoiding the resource pool sensing that may be needed to select a resource to be reserved. In addition, the UE-B  704  can conserve power by avoiding the transmission of reservation signaling that may be necessary to reserve a sidelink resource. Instead, in this example, the UE-A  702  performs any needed sensing, and sends the resource reservation signaling. 
     In some implementations of  FIG. 7 , the resource reservation by UE-A  702  may occur in response to a certain type of transmission. For example, if the UE-A  702  is a V-UE and detects or receives a sidelink transmission by UE-B  704  implemented as a P-UE, the UE-A  702  (e.g., V-UE) may reserve resources for any P-UE transmissions. The reserved resource(s) may be used by the specific P-UE (e.g., UE-B  704 ) that sent the sidelink transmission, or may be used by other P-UEs. Additionally, the reserved sidelink resource(s) may be used for any communications by a P-UE, whether with a V-UE or other type of UE. 
     In some implementations of  FIG. 7 , certain types of UEs may always perform resource reservation for another type of UE. In a first example, a V-UE (e.g., UE-A  702 ) in any communication with a P-UE (e.g., UE-B  704 ) may reserve sidelink resources for the P-UE. In at least one implementation, when the V-UE transmits a safety message related to pedestrians (e.g., for a P-UE), the V-UE may also reserve a sidelink resource for P-UE transmissions. Accordingly, any P-UE that receives the V-UE safety message may transmit in the reserved sidelink resource(s). 
     In a second example, a UE with a larger capability in a sidelink UE pair/group may reserve resources for other UEs in the pair/group. For instance, a smartphone UE may have a larger capability compared with a smartwatch UE or other wearable UE. In such an example, the smartphone UE may reserve sidelink resources for the smartwatch UE. 
     In a third example, a sidelink UE group may select a UE in the group as the header. For instance, a sidelink UE group may elect a UE in the group to be the header. In such an example, the header UE may perform sensing and may reserve sidelink resources for the other UEs in the group. 
     In a forth example, an RSU (road side unit, a node communicating with UEs on sidelink) may reserve resources for V-UEs or P-UEs for sidelink transmissions. For instance, an RSU may monitor/sense the sidelink resources and reserve one or more resources based on sensing results. 
       FIG. 8  is a block diagram illustrating select components of a wireless communication device  800  employing a processing system  802  according to at least one example of the present disclosure. The wireless communication device  800  may be a power-sensitive wireless communication device, as described herein. 
     In this example, the processing system  802  is implemented with a bus architecture, represented generally by the bus  804 . The bus  804  may include any number of interconnecting buses and bridges depending on the specific application of the processing system  802  and the overall design constraints. The bus  804  communicatively couples together various circuits including one or more processors (represented generally by the processing circuit  806 ), a memory  808 , and computer-readable media (represented generally by the storage medium  810 ). The bus  804  may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. 
     A bus interface  812  provides an interface between the bus  804  and a transceiver  814 . The transceiver  814  provides a means for communicating with various other apparatus over a transmission medium. For example, the transceiver  814  may include a receive chain to receive one or more wireless signals, and/or a transmit chain to transmit one or more wireless signals. Depending upon the nature of the apparatus, a user interface  816  (e.g., keypad, display, speaker, microphone, joystick) may also be provided. 
     The processing circuit  806  is responsible for managing the bus  804  and general processing, including the execution of programming stored on the computer-readable storage medium  810 . The programming, when executed by the processing circuit  806 , causes the processing system  802  to perform the various functions described below for any particular apparatus. The computer-readable storage medium  810  and the memory  808  may also be used for storing data that is manipulated by the processing circuit  806  when executing programming. As used herein, the term “programming” shall be construed broadly to include without limitation instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. 
     The processing circuit  806  is arranged to obtain, process and/or send data, control data access and storage, issue commands, and control other desired operations. The processing circuit  806  may include circuitry adapted to implement desired programming provided by appropriate media, and/or circuitry adapted to perform one or more functions described in this disclosure. For example, the processing circuit  806  may be implemented as one or more processors, one or more controllers, and/or other structure configured to execute executable programming and/or execute specific functions. Examples of the processing circuit  806  may include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) and/or other programmable logic component, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may include a microprocessor, as well as any conventional processor, controller, microcontroller, or state machine. The processing circuit  806  may also be implemented as a combination of computing components, such as a combination of a DSP and a microprocessor, a number of microprocessors, one or more microprocessors in conjunction with a DSP core, an ASIC and a microprocessor, or any other number of varying configurations. These examples of the processing circuit  806  are for illustration and other suitable configurations within the scope of the present disclosure are also contemplated. 
     In some instances, the processing circuit  806  may include a sidelink communication circuit and/or module  818 . The sidelink communication circuit/module  818  may generally include circuitry and/or programming (e.g., programming stored on the storage medium  810 ) adapted to perform one or more of the functions, processes or steps described herein with reference to  FIGS. 1-7, 9, and 10 . As used herein, reference to circuitry and/or programming may be generally referred to as logic (e.g., logic gates and/or data structure logic). 
     The storage medium  810  may represent one or more computer-readable devices for storing programming, such as processor executable code or instructions (e.g., software, firmware), electronic data, databases, or other digital information. The storage medium  810  may also be used for storing data that is manipulated by the processing circuit  806  when executing programming. The storage medium  810  may be any available non-transitory media that can be accessed by a general purpose or special purpose processor, including portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing and/or carrying programming. By way of example and not limitation, the storage medium  810  may include a non-transitory computer-readable storage medium such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical storage medium (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, and/or other mediums for storing programming, as well as any combination thereof. 
     The storage medium  810  may be coupled to the processing circuit  806  such that the processing circuit  806  can read information from, and write information to, the storage medium  810 . That is, the storage medium  810  can be coupled to the processing circuit  806  so that the storage medium  810  is at least accessible by the processing circuit  806 , including examples where the storage medium  810  is integral to the processing circuit  806  and/or examples where the storage medium  810  is separate from the processing circuit  806  (e.g., resident in the processing system  802 , external to the processing system  802 , distributed across multiple entities). 
     Programming stored by the storage medium  810 , when executed by the processing circuit  806 , can cause the processing circuit  806  to perform one or more of the various functions and/or process steps described herein. In at least some examples, the storage medium  810  may include sidelink communication operations  820 . The various operations may generally be adapted to cause the processing circuit  806  to perform one or more of the functions, processes or steps described herein with reference to  FIGS. 1-7, 9, and 10 . Thus, according to one or more aspects of the present disclosure, the processing circuit  806  is adapted to perform (independently or in conjunction with the storage medium  810 ) any or all of the processes, functions, steps and/or routines for any or all of the wireless communication devices described herein (e.g., scheduled entity  106 ,  107 , UE  222 ,  224 ,  226 ,  228 ,  230 ,  232 ,  234 ,  236 ,  238 ,  240 , and  242 , UE-A  502 ,  602 ,  702 , UE-B  504 ,  604 ,  704 ). As used herein, the term “adapted” in relation to the processing circuit  806  may refer to the processing circuit  806  being one or more of configured, employed, implemented, and/or programmed (in conjunction with the storage medium  810 ) to perform a particular process, function, step and/or routine according to various features described herein. 
     Referring to  FIG. 9 , a flow diagram is shown illustrating a wireless communication method (e.g., operational on or via a wireless communication device  800 ) according to some examples. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the method may be performed by the wireless communication device  800 , as described above and illustrated in  FIG. 8 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At  902 , the wireless communication device may send a reservation signal to reserve one or more sidelink resources for use by another device. For example, the processing system  802  may include logic (e.g., sidelink communication circuit/module  818  and/or sidelink communication operations  820 ) to transmit via the transceiver  814  the reservation signaling to reserve the one or more sidelink resources for use by the other device. 
     In some implementations, such as the example described above with reference to  FIG. 7 , the wireless communication device may transmit the reservation signal in response to receiving an initial sidelink transmission from the other device. Such an initial sidelink transmission may include at least one of a sidelink resource request or sidelink traffic from the other device. In some implementations, the initial sidelink transmission may further include a location indicator configured to indicate the location of the other device. In instances where the initial sidelink transmission includes such a location indicator, the wireless communication device may transmit the reservation signal when the other device is within a range threshold (e.g., less than a threshold distance from the wireless communication device), and to avoid transmitting the reservation signal when the other device is outside of the range threshold (e.g., more than the threshold distance from the wireless communication device). 
     In some implementations, such as the example described above with reference to  FIG. 6 , the wireless communication device may transmit a pedestrian safety message (PSM) together with the reservation signal. 
     At  904 , the wireless communication device may receive a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources. For example, the processing system  802  may include logic (e.g., sidelink communication circuit/module  818  and/or sidelink communication operations  820 ) to receive a sidelink transmission via the transceiver  814  from the other device on at least a portion of the one or more reserved sidelink resources. 
     In some implementations, such as the example described above with reference to  FIG. 6 , the wireless communication device may monitor the one or more reserved sidelink resources for a sidelink transmission from the other device. In such implementations, the wireless communication device may power down one or more components of the transceiver (e.g., transceiver  814 ) during sidelink resources outside of the one or more reserved sidelink resources, and to power up the one or more components of the transceiver to receive transmissions during the one or more reserved sidelink resources. 
     In some implementations, the wireless communication device may sense a sidelink resource pool to determine resource usage prior to sending the reservation signal, and to select the one or more sidelink resources based on the sensing of the sidelink resource pool. 
     Referring to  FIG. 10 , a flow diagram is shown illustrating a wireless communication method (e.g., operational on or via a wireless communication device  800 ) according to some embodiments. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the method may be performed by the wireless communication device  800 , as described above and illustrated in  FIG. 8 , by a processor or processing system, or by any suitable means for carrying out the described functions. 
     At  1002 , a wireless communication device may detect a reservation signal from another device, where the reservation signal is configured to reserve one or more sidelink resources. For example, the processing system  802  may include logic (e.g., sidelink communication circuit/module  818  and/or sidelink communication operations  820 ) to detect via the transceiver  814  a reservation signal from another device, where the reservation signal is configured to reserve one or more sidelink resources. In some implementations, detecting the reservation signal may further include detecting a pedestrian safety message (PSM) sent in addition to the reservation signal. 
     In some implementations, such as the example described above with reference to  FIG. 7 , the wireless communication device may transmit via the transceiver (e.g., transceiver  814 ) an initial sidelink transmission prior to detecting the reservation signal from the other device. The initial sidelink transmission may include at least one of a data transmission and/or a sidelink resource reservation request. In some implementations, the initial sidelink transmission may further include a current location for the wireless communication device. After sending the initial sidelink transmission, the wireless communication device may monitor the resource reservation signaling via the transceiver for the reservation signal. 
     At  1004 , the wireless communication device may transmit a sidelink transmission on at least a portion of the one or more sidelink resources reserved by the other device. For example, the processing system  802  may include logic (e.g., sidelink communication circuit/module  818  and/or sidelink communication operations  820 ) to transmit a sidelink transmission via the transceiver  814  on at least a portion of the one or more sidelink resources reserved by the other device. 
     In some implementations, the wireless communication device may transmit the sidelink transmission via the transceiver in each of the one or more sidelink resources reserved by the other device. For example, the wireless communication device may repeat the sidelink transmission to utilize each of the one or more sidelink resources reserved by the other device, or by sending different packets in each of the multiple reserved sidelink resources. In some implementations, the wireless communication device may transmit via the transceiver the sidelink transmission in one of the one or more sidelink resources reserved by the other device according to a pre-defined rule. 
     The following provides an overview of aspects of the present disclosure: 
     Aspect 1: A method of wireless communication, the method comprising: transmitting a reservation signal to reserve one or more sidelink resources for use by another device; and receiving a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources. 
     Aspect 2: The method of aspect 1, wherein transmitting the reservation signal to reserve the one or more sidelink resources for use by the other device comprises: transmitting the reservation signal to reserve the one or more sidelink resources for use by the other device in response to receiving an initial sidelink transmission from the other device. 
     Aspect 3: The method of aspect 2, wherein the initial sidelink transmission from the other device comprises a location indicator associated with the other device. 
     Aspect 4: The method of aspect 3, wherein transmitting the reservation signal to reserve the one or more sidelink resources for use by the other device comprises transmitting the reservation signal to reserve the one or more sidelink resources for use by the other device when the location indicator indicates the other device is within a range threshold. 
     Aspect 5: The method of aspect, wherein receiving a sidelink transmission from the other device on at least a portion of the one or more reserved sidelink resources comprises monitoring the one or more reserved sidelink resources for a sidelink transmission from the other device. 
     Aspect 6: The method of aspect 5, further comprising: powering down one or more components of a transceiver during sidelink resources outside of the one or more reserved sidelink resources; and powering up the one or more components of the transceiver to receive transmissions during the one or more reserved sidelink resources. 
     Aspect 7: The method of any of aspects 1 through 6, further comprising: sensing a sidelink resource pool to determine resource usage prior to transmitting the reservation signal; and selecting the one or more sidelink resources based on the sensing of the sidelink resource pool. 
     Aspect 8: The method of any of aspects 1, 5, 6, or 7, wherein transmitting the reservation signal to reserve the one or more sidelink resources for use by the other device comprises: transmitting a pedestrian safety message together with the reservation signal. 
     Aspect 9: A wireless communication device comprising a transceiver and a processing circuit communicatively coupled together, the processing circuit configured to perform a method of any one of aspects 1 through 8. 
     Aspect 10: A method of wireless communication, the method comprising: detecting a reservation signal from another device, wherein the reservation signal is configured to reserve one or more sidelink resources; and transmitting a sidelink transmission on the one or more of the sidelink resources reserved by the other device. 
     Aspect 11: The method of aspect 10, further comprising: transmitting an initial sidelink transmission prior to detecting the reservation signal from the other device, the initial sidelink transmission comprising at least one of a data transmission or a sidelink resource reservation request; and monitoring the resource reservation signaling for the reservation signal after transmitting the initial sidelink transmission. 
     Aspect 12: The method of aspect 11, wherein the initial sidelink transmission further includes a location indicator configured to indicate a current location of the wireless communication device that transmits the initial sidelink transmission. 
     Aspect 13: The method of any of aspects 10 through 12, wherein transmitting the sidelink transmission on the one or more sidelink resources reserved by the other device comprises: transmitting the sidelink transmission in each of the one or more sidelink resources reserved by the other device. 
     Aspect 14: The method of aspect 13, wherein transmitting the sidelink transmission in each of the one or more sidelink resources reserved by the other device comprises: repeating the sidelink transmission to utilize each of the one or more sidelink resources reserved by the other device. 
     Aspect 15: The method of any of aspects 10 through 12, wherein transmitting the sidelink transmission on the one or more sidelink resources reserved by the other device comprises: transmitting the sidelink transmission in one of the one or more sidelink resources reserved by the other device according to a pre-defined rule. 
     Aspect 16: The method of aspect 1, wherein detecting the reservation signal from the other device further comprises: detecting a pedestrian safety message in addition to the reservation signal. 
     Aspect 17: A wireless communication device comprising a transceiver and a processing circuit communicatively coupled together, the processing circuit configured to perform a method of any one of aspects 10 through 16. 
     Aspect 18: An apparatus configured for wireless communication comprising at least one means for performing a method of any one of aspects 1 through 8 or 10 through 16. 
     Aspect 19: A non-transitory processor-readable storage medium storing processor-executable instructions for causing a processing circuit to perform a method of any one of aspects 1 through 8 or 10 through 16. 
     Several aspects of a wireless communication network have been presented with reference to an exemplary implementation. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards. 
     By way of example, various aspects may be implemented within other systems defined by 3GPP or combinations of such systems. These systems may include candidates such as 5G New Radio (NR), Long-Term Evolution (LTE), the Evolved Packet System (EPS), the Universal Mobile Telecommunication System (UMTS), and/or the Global System for Mobile (GSM). Various aspects may also be extended to systems defined by the 3rd Generation Partnership Project 2 (3GPP2), such as CDMA2000 and/or Evolution-Data Optimized (EV-DO). Other examples may be implemented within systems employing IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system. 
     Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration.” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another-even if they do not directly physically touch each other. For instance, a first object may be coupled to a second object even though the first object is never directly physically in contact with the second object. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure. 
     While the above discussed aspects, arrangements, and embodiments are discussed with specific details and particularity, one or more of the components, steps, features and/or functions illustrated in  FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9 , and/or  10  may be rearranged and/or combined into a single component, step, feature or function or embodied in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added or not utilized without departing from the novel features of the present disclosure. The apparatus, devices and/or components illustrated in  FIGS. 1, 2, 3, 5, 6, 7 , and/or  8  may be configured to perform or employ one or more of the methods, features, parameters, and/or steps described herein with reference to  FIGS. 4, 5, 6, 7, 9 , and/or  10 . The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware. 
     It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein. 
     The various features associate with the examples described herein and shown in the accompanying drawings can be implemented in different examples and implementations without departing from the scope of the present disclosure. Therefore, although certain specific constructions and arrangements have been described and shown in the accompanying drawings, such embodiments are merely illustrative and not restrictive of the scope of the disclosure, since various other additions and modifications to, and deletions from, the described embodiments will be apparent to one of ordinary skill in the art. Thus, the scope of the disclosure is only determined by the literal language, and legal equivalents, of the claims which follow.