Patent Publication Number: US-2021176779-A1

Title: Two-stage grant for uplink data transmission in new radio-unlicensed (nr-u)

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. application Ser. No. 16/433,393, filed Jun. 6, 2019, which claims priority to and the benefit of India Patent Application No. 201841021536, filed Jun. 8, 2018, and Indian Patent Application No. 201841030707, filed Aug. 16, 2018, each of which is hereby incorporated by reference in its entirety as if fully set forth below and for all applicable purposes. 
    
    
     TECHNICAL FIELD 
     This application relates to wireless communication systems, and more particularly to communicating a two-stage grant for communicating in a communication medium shared by multiple network operating entities. 
     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 capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless multiple-access communications system may include a number of base stations (BSs), each simultaneously supporting communications for multiple communication devices, which may be otherwise known as user equipment (UE). 
     To meet the growing demands for expanded mobile broadband connectivity, wireless communication technologies are advancing from the Long-Term Evolution (LTE) technology to a next generation new radio (NR) technology. For example, NR may operate over a wider bandwidth (BW) at higher frequencies than LTE. In addition, NR introduces the concept of BWPs, where a BS may dynamically configure a UE to communicate over a portion of a network system BW instead of over the entire network system BW. The use of BWPs can provide several benefits, such as reducing UE BW capability requirements, reducing power consumptions at UEs, reducing signaling overheads, and/or allowing for load balancing within a component carrier (CC), despite the wider network system BW. Further, NR may operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing enables operators to opportunistically aggregate spectrums to dynamically support high-BW services. Spectrum sharing can extend the benefit of NR technologies to operating entities that may not have access to a licensed spectrum. 
     One approach to avoiding collisions when communicating in a shared spectrum or an unlicensed spectrum is to use a listen-before-talk (LBT) procedure to ensure that the shared channel is clear before transmitting a signal in the shared channel. A transmitting node may listen to one or more channels (e.g., frequency subbands) within the frequency spectrum. Depending on the LBT result, the transmitting node may access one or more channels. 
     BRIEF SUMMARY OF SOME EXAMPLES 
     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. 
     For example, in an aspect of the disclosure, a method of wireless communication includes communicating, by a first wireless communication device with a second wireless communication device, a first scheduling grant; communicating, by the first wireless communication device with the second wireless communication device, a second scheduling grant including at least one of a start slot index (SSI) or a slot format indicator (SFI); and communicating, by the first wireless communication device with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     In an additional aspect of the disclosure, an apparatus includes a transceiver configured to communicate, with a second wireless communication device, a first scheduling grant; communicate, with the second wireless communication device, a second scheduling grant including at least one of a SSI or a SFI; and communicate, by the first wireless communication device with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     In an additional aspect of the disclosure, a computer-readable medium having program code recorded thereon, the program code includes code for causing a first wireless communication device to communicate, with a second wireless communication device, a first scheduling grant; code for causing a first wireless communication device to communicate, with a second wireless communication device, a second scheduling grant including at least one of a SSI or a SFI; and code for causing a first wireless communication device to communicate, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     In an additional aspect of the disclosure, an apparatus includes means for communicating, with a second wireless communication device, a first scheduling grant; means for communicating, with a second wireless communication device, a second scheduling grant including at least one of a SSI or a SFI; and means for communicating, with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     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  illustrates a wireless communication network according to some embodiments of the present disclosure. 
         FIG. 2  illustrates a scheduling scheme according to embodiments of the present disclosure. 
         FIG. 3  is a block diagram of an exemplary base station (BS) according to embodiments of the present disclosure. 
         FIG. 4  is a block diagram of an exemplary user equipment (UE) according to embodiments of the present disclosure. 
         FIG. 5  illustrates a scheduling scheme for uplink (UL) data transmissions according to embodiments of the present disclosure. 
         FIG. 6  is a signaling diagram for communicating in a shared communication medium according to embodiments of the present disclosure. 
         FIG. 7  illustrates a scheduling scheme for UL data transmissions according to embodiments of the present disclosure. 
         FIG. 8  is a signaling diagram for communicating in a shared communication medium according to embodiments of the present disclosure. 
         FIG. 9  is a flow diagram of a two-stage scheduling grant communication method according to embodiments of the present disclosure. 
     
    
    
     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 the 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 in order to avoid obscuring such concepts. 
     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. In various embodiments, 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, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably. 
     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 Global System for Mobile Communications (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 aim to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces. 
     In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order 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 (e.g., ˜1M nodes/km 2 ), ultra-low complexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g., ˜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 (e.g., ˜99.9999% reliability), ultra-low latency (e.g., ˜1 milliseconds (ms)), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ˜10 Tbps/km 2 ), extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations. 
     The 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having 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 with 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 3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like BW. 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 BW. 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 BW. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW. 
     The scalable numerology of the 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 allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with UL/DL scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/DL that may be flexibly configured on a per-cell basis to dynamically switch between UL and DL to meet the current traffic needs. 
     Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented, or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented, or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. 
     A BS may partition a shared frequency band or an unlicensed frequency band into a plurality of channels. Channel access in the frequency band may be in units of channels. A BS or a UE may perform an LBT in the frequency band and may access one or more of the channels based on the result of the LBT. While the disclosed embodiments are described in the context of NR-unlicensed (NR-U), the disclosed embodiments are suitable for use with any wireless communication networks that operate over a shared frequency band or an unlicensed frequency band. 
     The present disclosure provides mechanisms for utilization of a two-stage grant for communicating in a communication medium shared by multiple network operating entities. In an example, a first wireless communication device communicates with a second wireless communication device a first scheduling grant and a second scheduling grant. The second scheduling grant may include at least one of a start slot index (SSI) or a slot format indicator (SFI). The SSI or SFI may provide an indication regarding a proper time to communicate an uplink communication signal. Additionally, the first wireless communication device communicates with the second wireless communication device an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     The first scheduling grant is transmitted in a first stage and the second scheduling grant is transmitted in a second stage of the two-stage grant technique. The first and second scheduling grants may be included in separate TXOPs. Additionally, the UL communication signal may be communicated in the subsequent TXOP. In an example, a BS transmits a first UL scheduling grant in one TXOP and transmits a second UL scheduling grant in a subsequent TXOP. The UE receives the first and second UL scheduling grants. Additionally, the UE transmits an UL data packet in the subsequent TXOP based on the first and second scheduling grants. The UL communication signal may also be referred to as an UL data packet. 
       FIG. 1  illustrates a wireless communication network  100  according to embodiments of the present disclosure. The network  100  may be a 5G network. The network  100  includes a number of base stations (BSs)  105  and other network entities. A BS  105  may be a station that communicates with UEs  115  and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each BS  105  may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this geographic coverage area of a BS  105  and/or a BS subsystem serving the coverage area, depending on the context in which the term is used. 
     A BS  105  may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cells. A macro cell generally covers a relatively large geographic area (e.g., 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 (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like). A BS for a macro cell may be referred to as a macro BS. A BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS or a home BS. In the example shown in  FIG. 1 , the BSs  105   d  and  105   e  may be regular macro BSs, while the BSs  105   a - 105   c  may be macro BSs enabled with one of 3 dimension (3D), full dimension (FD), or massive MIMO. The BSs  105   a - 105   c  may take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. The BS  105   f  may be a small cell BS which may be a home node or portable access point. A BS  105  may support one or multiple (e.g., two, three, four, and the like) cells. 
     The network  100  may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. 
     The UEs  115  are dispersed throughout the wireless network  100 , and each UE  115  may be stationary or mobile. A UE  115  may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE  115  may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE  115  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, the UEs  115  that do not include UICCs may also be referred to as internet of everything (IoE) devices. The UEs  115   a - 115   d  are examples of mobile smart phone-type devices accessing network  100 . A UE  115  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. The UEs  115   e - 115   k  are examples of various machines configured for communication that access the network  100 . A UE  115  may be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In  FIG. 1 , a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE  115  and a serving BS  105 , which is a BS designated to serve the UE  115  on the DL and/or uplink, or desired transmission between BSs, and backhaul transmissions between BSs. 
     In operation, the BSs  105   a - 105   c  may serve the UEs  115   a  and  115   b  using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. The macro BS  105   d  may perform backhaul communications with the BSs  105   a - 105   c , as well as small cell, the BS  105   f . The macro BS  105   d  may also transmit multicast services which are subscribed to and received by the UEs  115   c  and  115   d . 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. 
     The network  100  may also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such as the UE  115   e , which may be a drone. Redundant communication links with the UE  115   e  may include links from the macro BSs  105   d  and  105   e , as well as links from the small cell BS  105   f . Other machine type devices, such as the UE  115   f  (e.g., a thermometer), the UE  115   g  (e.g., smart meter), and UE  115   h  (e.g., wearable device) may communicate through the network  100  either directly with BSs, such as the small cell BS  105   f , and the macro BS  105   e , or in multi-hop configurations by communicating with another user device which relays its information to the network, such as the UE  115   f  communicating temperature measurement information to the smart meter, the UE  115   g , which is then reported to the network through the small cell BS  105   f . The network  100  may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such as in a vehicle-to-vehicle (V2V) communication. 
     In some implementations, the network  100  utilizes OFDM-based waveforms for communications. An OFDM-based system may partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier may be modulated with data. In some instances, the subcarrier spacing (SCS) between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be partitioned into subbands. In other instances, the subcarrier spacing and/or the duration of TTIs may be scalable. 
     In an embodiment, the BSs  105  can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RB)) for downlink (DL) and uplink (UL) transmissions in the network  100 . DL refers to the transmission direction from a BS  105  to a UE  115 , whereas UL refers to the transmission direction from a UE  115  to a BS  105 . The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes, for example, about 10. Each subframe can be divided into slots, for example, about 2. Each slot may be further divided into mini-slots. In a frequency-division duplexing (FDD) mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In a time-division duplexing (TDD) mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame may be used for DL transmissions and another subset of the subframes (e.g., UL subframes) in the radio frame may be used for UL transmissions. 
     The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are predetermined signals that facilitate the communications between the BSs  105  and the UEs  115 . For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, a BS  105  may transmit cell specific reference signals (CRSs) and/or channel state information—reference signals (CSI-RSs) to enable a UE  115  to estimate a DL channel. Similarly, a UE  115  may transmit sounding reference signals (SRSs) to enable a BS  105  to estimate a UL channel Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data. In some embodiments, the BSs  105  and the UEs  115  may communicate using self-contained subframes. A self-contained subframe may include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL communication than UL communication. A UL-centric subframe may include a longer duration for UL communication than DL communication. 
     In an embodiment, the network  100  may be an NR network deployed over a licensed spectrum. The BSs  105  can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) in the network  100  to facilitate synchronization. The BSs  105  can broadcast system information associated with the network  100  (e.g., including a master information block (MIB), remaining minimum system information (RMSI), and other system information (OSI)) to facilitate initial network access. In some instances, the BSs  105  may broadcast the PSS, the SSS, the MIB, the RMSI, and/or the OSI in the form of synchronization signal blocks (SSBs). 
     In an embodiment, a UE  115  attempting to access the network  100  may perform an initial cell search by detecting a PSS from a BS  105 . The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE  115  may then receive a SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The SSS may also enable detection of a duplexing mode and a cyclic prefix length. Some systems, such as TDD systems, may transmit an SSS but not a PSS. Both the PSS and the SSS may be located in a central portion of a carrier, respectively. 
     After receiving the PSS and SSS, the UE  115  may receive a MIB, which may be transmitted in the physical broadcast channel (PBCH). The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE  115  may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource configuration (RRC) information related to random access channel (RACH) procedures, paging, physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), power control, SRS, and cell barring. After obtaining the MIB, the RMSI and/or the OSI, the UE  115  can perform a random access procedure to establish a connection with the BS  105 . After establishing a connection, the UE  115  and the BS  105  can enter a normal operation stage, where operational data may be exchanged. 
     In an embodiment, the network  100  may operate over a shared frequency band or an unlicensed frequency band, for example, at about 3.5 gigahertz (GHz), sub-6 GHz or higher frequencies. For example, the BSs  105  and the UEs  115  may be operated by multiple network operating entities sharing resources in the shared communication medium and may employ a listen-before-talk (LBT) procedure to reserve transmission opportunities (TXOPs) in the shared medium for communications. The network  100  may partition the frequency band into multiple channels, for example, each occupying about 20 megahertz (MHz). 
       FIG. 2  illustrates a scheduling scheme  200  according to embodiments of the present disclosure. The scheduling scheme  200  may correspond to a scheduling scheme using a two-stage scheduling grant communicated between a BS  105  and a UE  115  of the network  100 . In  FIG. 2 , the x-axis represents time in some constant units.  FIG. 2  shows a frame structure  201  including a plurality of slots  204  in time. In the scheme  200 , a BS of a particular operating entity (e.g., Operator A) may successfully contend for a plurality of TXOPs  202  in a shared frequency spectrum. The TXOPs  202  may be non-continuous in time and may refer to an amount of time a station can send frames when it has won contention for the wireless medium. As shown, the TXOPs  202   a1  and  202   a2  are separated by a time period  206  corresponding to TXOPs of other network operating entities (e.g., Operators B and C). 
     Each TXOP  202  may include a plurality of slots  204 . The slots  204  are indexed from S0 to S9. A BS may communicate with a UE in units of slots  204 . The slots  204  may also be referred to as transmission time intervals (TTIs). Each slot  204  or TTI carries a medium access control (MAC) layer transport block. Each slot  204  may include a number of symbols in time and a number of frequency tones in frequency. Each slot  204  may include a DL control portion followed by at least one of a subsequent DL data portion, UL data portion, and/or a UL control portion. In the context of LTE, the DL control portion, the DL data portion, the UL data portion, and the UL control portion may be referred to as a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), and a physical uplink control channel (PUCCH), respectively. 
     The BS  105  may communicate a first scheduling grant and a second scheduling grant with the UE  115 . The BS and the UE may further communicate based on a parameter  214 , denoted as K2. The parameter  214  indicates a time period between reception by the UE of an UL scheduling grant and an active corresponding UL data transmission (e.g., PUSCH transmission). The parameter  214  may be indicated in units of slots  204 . As an example, the parameter  214  may indicate a value that is 0 or more (e.g., K2=2). In the context of LTE, the parameter  214  may be indicated in a DL control information (DCI) carried in a PDCCH. The pattern-filled boxes represent transmissions of DL control information, DL data, UL data, an ACK, and/or an NACK in corresponding slots  204 . While an entire slot  204  is pattern-filled, a transmission may occur only in a corresponding portion of the slot  204 . 
     In scheme  200 , the BS may indicate scheduling information using two UL scheduling grants. In a first stage of the two-stage grant, the BS transmits DL control information  222  in the slot  204  indexed S4 (e.g., in a DL control portion of the slot  204 ) in a first TXOP  202   a1 . The DL control information  222  may indicate a first UL scheduling grant for the UE. In response to receiving the first UL scheduling grant, the UE prepares an UL data packet (e.g., an encoded transport block) and holds its actual transmission until a second UL scheduling grant of the two-stage grant is received (e.g., in a subsequent TXOP). 
     At a later point in time, in a second stage of the two-stage grant, the BS transmits DL control information  230  in the slot  204  indexed S0 (e.g., in a DL control portion of the slot  204 ) in a second TXOP  202   a2 . The TXOP  202   a2  is subsequent to the TXOP  202   a1 . The DL control information  230  may indicate a second UL scheduling grant for the UE. As will be discussed further in the present disclosure, the second UL scheduling grant includes at least one of an SSI or SFI indicating when to start the UL transmission. In response to receiving the first and second UL scheduling grants, the UE transmits an UL data signal  232  to the BS in the slot  204  indexed S2 (e.g., in a UL data portion of the slot  204 ) based on a UL assignment and the parameter  214  (e.g., K2=2) in the second UL scheduling grant. The slot  204  indexed S2 is two slots from the slot  204  indexed S0. 
     An advantage of an embodiment may include mitigating the processing timeline delay in a UL data transmission because the delay in slots between the UL grant reception in DL and the UL data (PUSCH) transmission may be reduced. The (n+m) timeline specifies that if an UL scheduling grant is transmitted at the beginning of a slot n, then the earliest slot at which the UE can transmit is m slots later. In LTE, m is 4 slots, and each slot is 1 ms. Accordingly, in LTE, an UL data transmission scheduling scheme may provide for a BS to transmit an UL grant to a UE, which is expected to transmit 4 ms after reception of the UL grant. If the BS transmits an UL grant in subframe n of a TXOP to a UE, the earliest time in which the UE may transmit is subframe (n+4). Additionally, if the BS has no DL data, no data is transmitted between subframes n, (n+1), (n+2), and (n+3) and the medium is wasted. Accordingly, the time delay may be reduced and use of the medium optimized by use of the two-stage grant. 
     In NR, a non-trivial gap may exist between UL grant reception and UL PUSCH transmission, especially as SCS becomes higher; the higher the SCS, the smaller the slot duration. For example, it can be observed that only the (n+3) timeline is available with 120 Khz SCS, and only the (n+2) timeline is available with 60 Khz SCS. Even if the gap is nontrivial, the two-stage grant may be beneficial in NR because the bandwidth is wider than in LTE. For example, even if the timeline is (n+1), efficiency may still be gained by use of the two-stage grant, as will be further discussed in the present disclosure. In NR, a single-stage grant may indicate to the UE when to transmit the UL data packet based on the UE&#39;s processing capability. Accordingly, a timeline gap may exist between reception of the UL grant by the UE and transmission of the UL data packet that may be minimized with the use of the two-stage UL scheduling grant. 
     A two-stage UL scheduling grant may overcome the above disadvantages. The two-stage UL scheduling grant may correspond to coordination of UL data transmission communicated between a BS  105  and a UE  115  of the network  100 . Mechanisms for determining scheduling and/or transmission timeline in accordance with embodiments of the disclosure are described in greater detail herein. 
       FIG. 3  is a block diagram of an exemplary BS  300  according to embodiments of the present disclosure. The BS  300  may be a BS  105  as discussed above. As shown, the BS  300  may include a processor  302 , a memory  304 , an UL scheduling grant module  308 , a transceiver  310  including a modem subsystem  312  and a radio frequency (RF) unit  314 , and one or more antennas  316 . These elements may be in direct or indirect communication with each other, for example via one or more buses. 
     The processor  302  may have various features as a specific-type processor. For example, these may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor  302  may also be implemented as a combination of computing devices, e.g., 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. 
     The memory  304  may include a cache memory (e.g., a cache memory of the processor  302 ), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, a solid state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, the memory  304  includes a non-transitory computer-readable medium. The memory  304  may store instructions  306 . The instructions  306  may include instructions that, when executed by the processor  302 , cause the processor  302  to perform operations described herein with reference to the BSs  105  in connection with embodiments of the present disclosure. Instructions  306  may also be referred to as code. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements. 
     The UL scheduling grant module  308  may be implemented via hardware, software, or combinations thereof. For example, UL scheduling grant module  308  may be implemented as a processor, circuit, and/or instructions  306  stored in the memory  304  and executed by the processor  302 . The UL scheduling grant module  308  may be used for various aspects of the present disclosure. For example, the UL scheduling grant module  308  is configured to communicate with a second wireless communication device (e.g., UE  115 ) a first scheduling grant and a second scheduling grant. In an example, the UL scheduling grant module  308  encodes an UL scheduling grant, modulates the encoded UL scheduling grant (e.g., using OFDM), and then maps the modulation symbols on to control resources (e.g., in a PDCCH). The UL scheduling grant module  308  transmits the UL scheduling grant using the control resources, which may include frequency tones in one or more symbol time period. 
     In an example, in a first stage, the UL scheduling grant module  308  transmits a first UL scheduling grant in a first TXOP and in a second stage, transmits a second UL scheduling grant in a subsequent TXOP to the UE. The two-stage scheduling grant includes two individual UL scheduling grants. In some examples, the first UL scheduling grant includes a resource allocation (RA), a start and end symbol for the slot, modulation and coding scheme (MCS), a new data indicator (NDI), and an unknown slot index to indicate to the UE to hold its transmission, and the second UL scheduling grant includes an SSI indicating a slot at which to transmit the UL data. In some examples, the first UL scheduling grant includes an RA, a start and end symbol for the slot, MCS, NDI, and the K2 parameter, and the second UL scheduling grant includes an SFI that triggers activation of the first UL scheduling grant, where K2 stands for the timing delay between the UL burst to the UL transmission, and the UL burst may start a with flexible symbol or an UL symbol, which may be indicated in the SFI. The SFI is used to denote whether a given symbol (e.g., OFDM symbol) in a slot is used for UL, DL, or flexible link direction in the current TXOP. In particular, the SFI indicates a start of the UL burst. The UL scheduling grant module  308  is further configured to monitor for an uplink communication signal based on the first and second scheduling grants. In an example, the UL scheduling grant module  308  receives, based on the first scheduling grant and the second scheduling grant, an UL data packet from the UE. 
     As shown, the transceiver  310  may include the modem subsystem  312  and the RF unit  314 . The transceiver  310  can be configured to communicate bi-directionally with other devices, such as the UEs  115  and/or another core network element. The modem subsystem  312  may be configured to modulate and/or encode data according to a MCS, e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit  314  may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem  312  (on outbound transmissions) or of transmissions originating from another source such as a UE  115  or BS  105 . The RF unit  314  may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver  310 , the modem subsystem  312  and the RF unit  314  may be separate devices that are coupled together at the BS  105  or  300  to enable the BS  105  or  300  to communicate with other devices. 
     The RF unit  314  may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas  316  for transmission to one or more other devices. The antennas  316  may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver  310 . The antennas  316  may include multiple antennas of similar or different designs in order to sustain multiple transmission links. 
       FIG. 4  is a block diagram of an exemplary UE  400  according to embodiments of the present disclosure. The UE  400  may be a UE  115  as discussed above. As shown, the UE  400  may include a processor  402 , a memory  404 , a UL grant module  408 , an UL packet module  409 , a transceiver  410  including a modem subsystem  412  and an RF unit  414 , and one or more antennas  416 . These elements may be in direct or indirect communication with each other, for example, via one or more buses. 
     The processor  402  may include a CPU, a DSP, an ASIC, a controller, a FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor  402  may also be implemented as a combination of computing devices, e.g., 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. 
     The memory  404  may include a cache memory (e.g., a cache memory of the processor  402 ), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid state memory device, hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, the memory  404  includes a non-transitory computer-readable medium. The memory  404  may store instructions  406 . The instructions  406  may include instructions that, when executed by the processor  402 , cause the processor  402  to perform the operations described herein with reference to the UEs  115  in connection with embodiments of the present disclosure. Instructions  406  may also be referred to as code, which may be interpreted broadly to include any type of computer-readable statement(s) as discussed above with respect to  FIG. 3 . 
     The UL grant module  408  and/or UL packet module  409  may be implemented via hardware, software, or combinations thereof. For example, the UL grant module  408  and/or UL packet module  409  may be implemented as a processor, circuit, and/or instructions  406  stored in the memory  404  and executed by the processor  402 . The UL grant module  408  and/or UL packet module  409  may be used for various aspects of the present disclosure. For example, the UL grant module  408  is configured to communicate with a second wireless communication device (e.g., BS  105 ) a first scheduling grant and a second scheduling grant. In an example, in a first stage the UL grant module  408  receives a first UL scheduling grant in a first TXOP and in a second stage receives a second UL scheduling grant in a subsequent TXOP. In response to receiving the first scheduling grant, the UL packet module  409  prepares the UL data packet for transmission and holds its actual transmission until the UL grant module  408  receives a second scheduling grant associated with the first scheduling grant (e.g., based on a hybrid automatic repeat request (HARQ) identifier (ID) match or comparison). In an example, the first scheduling grant may be associated with the second scheduling grant if they have the same HARQ ID, even if not all the parameters in the grants are the same. The UL grant module  408  may receive one or more of the two-stage scheduling grants as discussed in the present disclosure. The UL packet module  409  is further configured to transmit an uplink communication signal based on the first and second scheduling grants. In an example, the UL packet module  409  transmits, based on the first scheduling grant and the second scheduling grant, an UL data packet to the BS. Mechanisms for communicating the scheduling grants are described in greater detail herein. 
     As shown, the transceiver  410  may include the modem subsystem  412  and the RF unit  414 . The transceiver  410  can be configured to communicate bi-directionally with other devices, such as the BSs  105 . The modem subsystem  412  may be configured to modulate and/or encode the data from the memory  404 , the UL grant module  408 , and/or the UL packet module  409  according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit  414  may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem  412  (on outbound transmissions) or of transmissions originating from another source such as a UE  115  or BS  105 . The RF unit  414  may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver  410 , the modem subsystem  412  and the RF unit  414  may be separate devices that are coupled together at the UE  115  or  400  to enable the UE  115  or  400  to communicate with other devices. 
     The RF unit  414  may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas  416  for transmission to one or more other devices. The antennas  416  may further receive data messages transmitted from other devices. The antennas  416  may provide the received data messages for processing and/or demodulation at the transceiver  410 . The antennas  416  may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit  414  may configure the antennas  416 . 
       FIG. 5  illustrates a scheduling scheme  500  for UL data transmissions according to embodiments of the present disclosure. The scheme  500  may be employed by the BSs  105 ,  300  and the UEs  115 ,  400  and illustrates scheduling and transmissions of UL data. The scheme  500  implements a two-stage UL grant scenario in which the BS transmits two individual UL grants at different TXOPs. 
     In the scheme  500 , a BS of a particular operating entity (e.g., Operator A) may successfully contend for a plurality of TXOPs  502  in a shared frequency spectrum  501 . The TXOPs  502  may be non-continuous in time and includes a plurality of slots  504 . As shown, the TXOPs  502   a1  and  502   a2  are separated by a time period  506  corresponding to TXOPs of other network operating entities (e.g., Operators B and C). In an example, the slots  504  may include a DL control portion (e.g., the DL control portion  222 ,  230 ) followed by at least one of a DL data portion, an UL control portion, or an UL data portion (e.g., the UL data portion  232 ). In some embodiments, each slot  504  may include a duration of about 1 ms or about 0.5 ms. While  FIG. 5  illustrates the TXOPs  502  including six slots  504 , the TXOPs  502  can include any suitable number of slots  504 . For example, a TXOP  502  can include fewer than six slots  504 . In another example, a TXOP  502  may include between seven to ten slots  504 . 
     In scheme  500 , in a first stage, the BS transmits a first UL scheduling grant  520  in a TXOP  502   a1  for a UE. The first UL scheduling grant  520  may indicate an RA, a start symbol and end symbol in a particular slot, an MCS, an NDI for a UL data transmission, but does not indicate the slot at which the UL data transmission is to start. The remaining slots in the first TXOP  502   a1  may include DL and/or UL symbols. In response to receiving the first UL scheduling grant  520 , the UE may prepare the UL data packet and have it ready for transmission. The preparation may include determining a transport block size based on parameters in the first scheduling grant, generating a transport block based on the transport block size, encoding the transport block, and/or modulating the encoded block. Accordingly, when the UE receives a second UL scheduling grant that matches the first UL scheduling grant, the UE may already have the UL data packet prepared and ready for transmission. Two scheduling grants match if they have the same ID (e.g., HARQ process ID). The first and second scheduling grants have the same ID so that the UE can associate them together. If two scheduling grants have different IDs, then they are separate grants and do not match. 
     Each DL control signal may include scheduling information. In an example, a DL control signal includes the first UL scheduling grant  520  in the slot  504  indexed S n . RRC may configure a 16-entry table including a first set of entries mapping to a single-stage grant and a second set of entries mapping to a two-stage grant. In this way, it may be unnecessary to change the UL grant signal itself. A four-bit time domain PUSCH resource field may map into the 16-entry table, which the BS may use to schedule the start symbol, end symbol, and start slot. If the UE receives entries mapping into the first set of entries, the UE treats the scheduling grant as a single-stage grant. If the UE receives entries mapping into the second set of entries, the UE treats the scheduling grant as part of a two-stage grant. 
     The second set of entries may indicate that the K2 parameter will be indicated in the second stage, and K2 in the first stage grant is undefined. The BS may configure the 16-entry table (e.g., the K2 parameter) based on the UE&#39;s capability report. For example, in NR the list of possible values for K2 that may be configured by RRC is {0, 1, 2, 5, 4, 5, 7, 8, 10, 16, 20, 32}. For the single stage grant, the BS may remove those values that the UE cannot support. For example, if the UE&#39;s timeline is (n+2), the BS may remove the values 0 and 1 from being possible values for K2. For the two-stage grant, once the UE receives the UL grant corresponding to an entry of the second set, the UE prepares the UL data packet, while holding its actual transmission. 
     In a second stage, the BS transmits a second UL scheduling grant  550  in a second TXOP  502   a2  for the UE. The second TXOP  502   a2  is transmitted subsequent to the first TXOP  502   a1 . When the BS gains access to the medium, the BS may transmit the second UL scheduling grant  550  that matches the first UL scheduling grant  520 . In an example, a DL control signal includes the second UL scheduling grant  550  in the slot  504  indexed S m . In an example, the second UL scheduling grant  550  indicates the SSI at which the UE is to transmit the UL data packet in the current TXOP  502   a2 . The SSI indicates the slot in which the UL data transmission associated with the first and second UL scheduling grants is to start. In other words, the SSI indicates when the active UL transmission will occur in the current TXOP. The parameter  214 , hereinafter denoted as K2, is submitted in the second UL scheduling grant  550  and specifies the SSI. Because the first UL scheduling grant  520  provides sufficient information for the UE to prepare its UL data packet for transmission, the second UL scheduling grant  550  may use a smaller DCI payload or may reuse the same DCI payload as the first UL scheduling grant  520 . 
     In the scheme  500 , the first UL scheduling grant  520  is transmitted in an earlier TXOP  502   a1  than the TXOP  502   a2  in which the second UL scheduling grant  550  is transmitted. In response to receiving the first and second UL scheduling grants, the UE can turn around much faster because the UL data packet may already be prepared by the time the UE receives the second UL scheduling grant. For example, depending on the UE&#39;s capability, the UE can transmit one slot after receiving the second UL scheduling grant  550 , with an (n+1) processing timeline. 
       FIG. 6  is a signaling diagram  600  for communicating in a shared communication medium according to embodiments of the present disclosure. Actions specified in the signaling diagram  600  can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device, such as the BSs  105  and the UEs  115 . The signaling diagram  600  may employ similar mechanisms as in the scheme  600 , described with respect to 
       FIG. 6 . As illustrated, the signaling diagram  600  includes a number of enumerated steps, but embodiments of the signaling diagram  600  may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. 
     The BS may issue multiple first UL scheduling grants to one or more UEs and subsequently issue a second UL scheduling grant that matches with one of them. In an example, the BS may update the UL data transmission based on the medium access status (e.g., channel status). As shown in signaling diagram  600 , in a first stage, the BS transmits a first UL scheduling grant  602  in a TXOP. The first UL scheduling grant  602  indicates that HARQ Process ID=1, K2 is unknown, and that the grant corresponds to channel  1  (e.g., a first frequency band). Based on the grant  602 , the BS requests that the UE transmit UL data on channel  1 . In response to receiving the first UL scheduling grant  602 , the UE prepares an UL data packet for HARQ Process ID=1 that may or may not be transmitted to the BS. 
     In a first stage, the BS transmits a first UL scheduling grant  604  in a TXOP. First grants  602  and  604  may be included in the same or different TXOPs. The first UL scheduling grant  604  indicates that HARQ Process ID=2, K2 is unknown, and that the grant corresponds to two channels. Based on the grant  604 , the BS requests that the UE transmit UL data on channels  1  and  2  (e.g., two frequency bands). In response to receiving the first UL scheduling grant  604 , the UE prepares an UL data packet for HARQ Process ID=2 that may or may not be transmitted to the BS. 
     As shown in this example, the UL scheduling grant(s) sent in the first stage does not specify the value of the parameter K2. Accordingly, the UE may prepare a few hypotheses corresponding to the multiple first UL scheduling grants. The BS may be unaware of which channels and/or how many channels it may check out (e.g., by performing medium sensing) until the BS checks out the channel(s). Multiple first stage grants may provide the BS with some flexibility in adapting the UL grant based on the channel checkout status. For example, based on the BS&#39;s medium access status, the BS may select a previously sent first UL scheduling grant by transmitting in the second stage of the two-stage UL grant a second UL scheduling grant that matches the selected grant. In an example, if the BS checks out only channel  1 , the BS may transmit a second UL scheduling grant (not shown), which matches the first UL scheduling grant  602 . In this example, both the first UL scheduling grant  602  and this second UL scheduling grant have the same HARQ processing ID=1. In contrast, if the BS checks out channels  1  and  2 , the BS transmits a second UL scheduling grant  606 , which matches the first UL scheduling grant  604 . Both the first UL scheduling grant  604  and the second UL scheduling grant  606  have the same HARQ processing ID=2. Additionally, the parameter K2=2 in the second UL scheduling grant  606 , which indicates that the SSI for active UL transmission is 2 slots later relative to the transmission of the second UL scheduling grant. As shown in signaling diagram  600 , in response to receiving the first and second UL scheduling grants  604  and  606 , respectively, the UE transmits the UL data packet  608  in accordance with the K2 parameter. In some examples, the same HARQ process ID may be used for the multiple first-stage grants. 
     The UE may maintain a capability report that is accessible by the BS. To prevent the UE from overexerting itself, the UE may indicate in its capability report the number of first stage scheduling grants that the UE supports. As such, the BS may know the maximum number of first stage scheduling grants (e.g., hypotheses) that it may send to the UE for a particular UL schedule. Additionally, the UE may indicate its processing timeline from reception of an UL scheduling grant to the UL data packet transmission when the UL data packet has not been prepared. In other words, the UE may indicate the processing timeline for the UE to decode a received UL scheduling grant and encode and/or modulate a data packet. Additionally, the UE may indicate its processing timeline from reception of an UL scheduling grant to the UL data packet transmission when the UL data packet is already prepared. In other words, the UE may indicate the processing timeline for the UE to decode a received UL scheduling grant and/or map an already prepared encoded/modulated packet to a particular channel for transmission. Accordingly, the BS may ensure that the SSI indicated in the second UL scheduling grant is consistent with the UE&#39;s processing timeline. A SSI is consistent with the UE&#39;s processing timeline if the UE has sufficient time to transmit UL data in accordance with the SSI. For example, if the UE is capable of decoding an UL grant and transmitting an UL data packet in two symbols, the second UL scheduling grant is transmitted at symbol n, and the start symbol is symbol n+3, the UE may turn around and transmit the UL data packet within the same slot. 
     Additionally, the RRC may configure the expiration time of first stage scheduling grants (e.g., X ms) associated with the two-stage grant. If the UE does not receive a matching second UL scheduling grant within the expiration time from when the UE detects the first UL scheduling grant, the UE may discard the first UL scheduling grant. 
     It may be unnecessary for the fields within the grants to be identical. Some of the parameters (e.g., RA, MCS, etc.) in the second UL scheduling grant may be different from the first UL scheduling grant. The second UL scheduling grant may overwrite the first UL scheduling grant, depending on the BS scheduling implementation. The BS may ensure that the updated UL scheduling grant is consistent with the UE&#39;s processing time line. A grant is consistent with the UE&#39;s processing timeline if the UE has sufficient time to transmit UL data in accordance with the SSI included in the grant. In some examples, the UE assumes that the second UL scheduling grant is consistent with the first UL scheduling grant. If the timeline (e.g., K2 value) for the second UL scheduling grant is sufficient for the UE to decode the grant and prepare a new UL data packet, the UE may follow the second UL scheduling grant and abandon the first UL scheduling grant. 
     The UE may indicate its processing timeline from reception of an UL scheduling grant to the UL data packet transmission when the UL data packet has not been prepared. In an example, the UE&#39;s capability report specifies that the UE needs (n+3) processing time for decoding a grant and preparing a new UL data packet for transmission. The timeline for the second UL scheduling grant is sufficient for the UE to decode the grant and prepare a new UL data packet if the value of K2 in the second grant is at least three. Accordingly, if the BS desires for the second UL scheduling grant to overwrite the first UL scheduling grant, it is desirable for the BS to know the UE&#39;s processing timeline capability and ensure that all other fields in the second UL scheduling grant are consistent with the first UL scheduling grant. 
     The second UL scheduling grant does not overwrite the first UL scheduling grant if the timeline (e.g., the K2 value) specified in the second UL scheduling grant is insufficient for the UE to decode the grant and prepare a new UL data packet. In keeping with the example above, if the value of K2 in the second grant is less than three (e.g., K2=1), the UE needs more processing time. If the second UL scheduling grant does not overwrite the first UL scheduling grant, both the first and second UL scheduling grants may result into the same transport block size (TBS) except for the K2 value. In an example, the first and second UL scheduling grants are consistent if the TBS size is the same. 
     The UE may indicate its processing timeline from reception of an UL scheduling grant to the UL data packet transmission when the UL data packet is already prepared. In an example, the UE&#39;s capability report specifies that the UE needs (n+1) processing time for decoding a grant and transmitting an already prepared UL data packet. The timeline for the second UL scheduling grant is sufficient for the UE to decode the grant and transmit the already prepared UL data packet if the value of K2 in the second grant is at least one. Here, the UE uses the original UL data packet prepared by the UE in response to the first UL scheduling grant for the UL transmission. As long as the original UL data packet can be used for the UL transmission, the first and second UL scheduling grants are consistent. Here, it is unnecessary for the UE to regenerate (e.g., re-encode) the UL data packet, and the transmission is remapped elsewhere. 
     For example, in the first UL scheduling grant the BS may schedule the UE to transmit the UL data packet in resource blocks  0 - 9 . In the matching second UL scheduling grant, the BS may remap this transmission and move the UE&#39;s UL transmission to resource blocks  10 - 19 . In another example, in the first UL scheduling grant the BS may request that the UE transmit on a first subband. If the BS is unable to check out the first subband but is able to check out a second subband, in the matching second UL scheduling grant, the BS may remap this transmission and request that the UE transmit on the second subband. In these examples, the UE transmits the original UL data packet that was prepared in response to the first UL scheduling grant. 
     In some examples, the BS ensures that the K2 specified in the second UL scheduling grant is sufficient for the UE to decode the grant and transmit an already prepared UL data packet. The K2 value specified in the second UL scheduling grant may be smaller than the K2 value specified in the single-stage UL scheduling grant. 
     Additionally, the RRC may configure the expiration time of first stage scheduling grants (e.g., X ms) associated with the two-stage grant. If the UE does not receive a matching second UL scheduling grant within the expiration time from when the UE detects a first UL scheduling grant, the UE may discard the first UL scheduling grant. 
       FIG. 7  illustrates a scheduling scheme  700  for UL data transmissions according to embodiments of the present disclosure. The scheme  700  may be employed by the BSs  105 ,  300  and the UEs  115 ,  400  and illustrates scheduling and transmissions of UL data. The scheme  700  implements a two-stage UL grant scenario in which the BS transmits in a first stage a first UL scheduling grant and transmits in a second stage a trigger that activates the first UL scheduling grant. 
     In scheme  700 , in a first stage, the BS transmits a first UL scheduling grant  720  in a TXOP  702   a1  for a UE. The first UL scheduling grant  720  may indicate the RA, start symbol and end symbol in a particular slot, MCS, and NDI. The first UL scheduling grant  720  may also specify the value of the K2 parameter, which may be interpreted as the delay from the UL start (e.g., the first UL symbol) to the UL data transmission (e.g., PUSCH transmission) in the subsequent TXOP. In the scheme  700 , the K2 parameter may be smaller and point to the timing delay of the UL transmission relative to the start of the UL burst in the next TXOP. In  FIG. 7 , K2=0 in the first UL scheduling grant  720 , which specifies that the delay from the UL start (e.g., the first UL symbol) to the UL data transmission is 0 slots. The remaining slots in the first TXOP  702   a1  include DL and/or UL symbols. In response to receiving the first UL scheduling grant  720 , the UE may prepare the UL data packet and have it ready for transmission. 
     In a second stage, the BS transmits a second UL scheduling grant  750  in a second TXOP  702   a2  for the UE. The second TXOP  702   a2  is transmitted subsequent to the first TXOP  702   a1 . In an example, the second UL scheduling grant  750  includes an SFI serving as a trigger that activates the first UL scheduling grant  720 . The SFI is used to denote whether a given symbol (e.g., OFDM symbol) in a slot is used for UL, DL, or a flexible link direction in the current TXOP. The UE detects the trigger and identifies the start of the UL burst and transmits accordingly to K2 from the start of the UL burst. 
     In the scheme  700 , it may be unnecessary to add a bit in the PUSCH to differentiate between single-stage and two-stage UL scheduling grant schemes. The two-stage UL scheduling grant may be indicated with a different RRC configuration of the 16 entries instead of introducing a field to differentiate between single-stage or two-stage scheduling grants. The BS may divide the 16 entries into a first set of entries mapping to a single-stage grant and into a second set of entries mapping to a two-stage grant. If the UE receives a grant corresponding to any entry in the first set, the UE may interpret the grant as a single-stage grant. If the UE receives a grant that points to any entry in the second set, the UE may interpret the grant as being part of a two-stage grant. The value of the K2 parameter may be interpreted as the delay from the UL start to the UL data transmission in the subsequent TXOP if the 4-bit PUSCH time assignment corresponds to the second set of entries mapping to the two-stage grant based on the RRC configuration. 
     In the scheme  700 , the UL transmission may start with flexible or UL slots/symbols, but does not start with the DL slots/symbols indicated in the SFI. The scheme  700  may convert the flexible slots/symbols into UL slots/symbols, which is consistent with NR philosophy that a dynamic DL/UL grant will overwrite the flexible symbols in SFI. The reference point from where to start the UL burst may start from the flexible symbol or UL symbol. 
     The first UL scheduling grant  720  issued in the previous TXOP  702   a1  can overwrite the flexible symbols, but not the DL symbols. TXOP  702   a2  includes 6 slots, with the slots  704  indexed S m+1  and S m+2  including DL symbols and the slots  704  indexed S m+3 , S m+4 , and S m+5  including UL or flexible symbols. The UE will look at the SFI and recognize that slots  704  indexed S m+1  and S m+2  include DL symbols. In NR, the UL burst may start with the earliest flexible symbols, which is slot  704  indexed S m+3 . In  FIG. 7 , K2=0 in the first UL scheduling grant  720 , which specifies that the delay from the slot  704  indexed S m+3  to the UL data transmission is 0 slots. Accordingly, the UE transmits the UL data packet at slot  704  indexed S m+3 . 
     As another example, in scheme  700 , if the first UL scheduling grant indicates that K2=1, the delay from the slot  704  indexed S m+3  to the UL data transmission is 1 slot. In this example, the UE transmits the UL data packet at slot  704  indexed S m+4 , which provides for a one slot timing delay from the UL burst to the UL transmission. 
     In its capability report, the UE may indicate the processing timeline from decoding the trigger to actual transmission of the UL data packet when the packet is already prepared and/or when the packet is not prepared. The BS may ensure that the K2 value specified in the first UL scheduling grant is consistent with the UE&#39;s processing timeline. K2 may be interpreted as the time delay from the trigger to the actual transmission of the UL data packet. 
       FIG. 8  is a signaling diagram  800  for communicating in a shared communication medium according to embodiments of the present disclosure. Actions specified in the signaling diagram  800  can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device, such as the BSs  105 ,  300  and the UEs  115 ,  400 . The signaling diagram  800  may employ similar mechanisms as in the scheme  700 , described with respect to  FIG. 7 . As illustrated, the signaling diagram  800  includes a number of enumerated steps, but embodiments of the signaling diagram  800  may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. 
     The BS may issue multiple first UL scheduling grants to one or more UEs and subsequently issue a second UL scheduling grant that matches with one of them. The multiple first UL scheduling grants may have different HARQ process IDs or different RAs, while having the same value for K2. In an example, the BS may update the UL data transmission based on the medium access status (e.g., channel status). As shown in signaling diagram  800 , in a first stage, the BS transmits a first UL scheduling grant  802  in a TXOP. The first UL scheduling grant  802  indicates that HARQ Process ID=1, K2=2, and that the grant corresponds to subband  1 . Based on the grant  802 , the BS requests that the UE transmit on subband  1 . In response to receiving the first UL scheduling grant  802 , the UE prepares an UL data packet for HARQ Process ID=1 that may or may not be transmitted to the BS. 
     In a first stage, the BS transmits a first UL scheduling grant  804  in a TXOP. Grants  802  and  804  may be included in the same or different TXOPs. The first UL scheduling grant  804  indicates that HARQ Process ID=2, K2=2, and that the grant corresponds to subband  2 . Based on the grant  802 , the BS requests that the UE transmit on subband  2 . In response to receiving the first UL scheduling grant  804 , the UE prepares an UL data packet for HARQ Process ID=2 that may or may not be transmitted to the BS. In some examples, the same HARQ process ID may be used for the multiple first-stage UL grants. 
     Accordingly, the UE may prepare a few hypotheses corresponding to the multiple first UL scheduling grants. The BS may be unaware of which channels/subbands and/or how many channels/subbands it may check out until the BS checks out the channel(s)/subbands. Multiple first stage grants may provide the BS with some flexibility in adapting the UL grant based on the channel/subband checkout status. The BS may access subband  2  and send a second UL scheduling grant  806 . In  FIG. 8 , the second UL scheduling grant  806  indicates that HARQ Process ID=1, K2=2, and that the grant corresponds to subband  1 , even though the BS actually checked out subband  2 . A channel/subband usage indicator or the UE may detect which channel/subband the BS checked out, and the UE may select the correct hypothesis among the multiple received first UL scheduling grants and transmit accordingly. Accordingly, the UE may detect that the BS checked out subband  2 , and in response to the first UL scheduling grant  804  and the second UL scheduling grant  806 , transmit the UL data packet  808  on subband  2 . 
     As discussed, the UE may maintain a capability report that is accessible by the BS. Additionally, the UE may indicate its processing timeline from reception of the trigger to the UL data packet transmission when the UL data packet has not been prepared and/or when the UL data packet has already been prepared. Accordingly, the BS may ensure that the K2 value indicated in the first UL scheduling grant is consistent with the UE&#39;s processing timeline. 
     Additionally, the RRC may configure the expiration time of first stage scheduling grants (e.g., X ms) associated with the two-stage grant. If the UE does not receive a matching second UL scheduling grant (e.g., the UL scheduling grant including the SSI or the SFI) within the expiration time from when the UE detects a first UL scheduling grant, the UE may discard the first UL scheduling grant. 
       FIG. 9  is a flow diagram of a two-stage scheduling grant communication method  900  according to embodiments of the present disclosure. Steps of the method  900  can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device, such as the UEs  115  and  400  and the BSs  105  and  300 . In some examples, the BS  300 , may utilize one or more components, such as the processor  302 , the memory  304 , the UL scheduling grant module  308 , the transceiver  310 , and/or the antennas  316  to execute the steps of method  900 . In an example, an apparatus includes means for communicating, with a UE, a first scheduling grant; means for communicating, with the UE, a second scheduling grant including at least one of a SSI or a SFI; and means for communicating, with the UE, an uplink communication signal based on the first scheduling grant and the second scheduling grant. In some examples, the UE  400 , may utilize one or more components, such as the processor  402 , the memory  404 , the UL grant module  408 , the UL packet module  409 , the transceiver  410 , and/or the antennas  416  to execute the steps of method  900 . In an example, an apparatus includes means for communicating, with a BS, a first scheduling grant; means for communicating, with the BS, a second scheduling grant including at least one of a SSI or a SFI; and means for communicating, with the BS, an uplink communication signal based on the first scheduling grant and the second scheduling grant. The method  900  may employ similar mechanisms as in the schemes  500 ,  700 . As illustrated, the method  900  includes a number of enumerated steps, but embodiments of the method  900  may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. 
     At step  910 , the method  900  includes communicating, by a first wireless communication device with a second wireless communication device, a first scheduling grant (e.g., the first scheduling grant  520 ,  720 ). In one embodiment, the first wireless communication device may correspond to a BS and the second wireless communication device may correspond to a UE. In another embodiment, the first wireless communication device may correspond to a UE and the second wireless communication device may correspond to a BS. 
     At step  920 , the method  900  includes communicating, by the first wireless communication device with the second wireless communication device, a second scheduling grant (e.g., the second scheduling grant  550 ,  750 ) including at least one of a SSI or SFI. In the scheme  500 , the first scheduling grant indicates the RA, start symbol and end symbol in a particular slot, MCS, NDI, but does not indicate the slot at which the UL data transmission is to start. Additionally, the second scheduling grant indicates the SSI, which specifies a slot at which to transmit the UL data in the current TXOP. In the scheme  700 , the first scheduling grant indicates the RA, start symbol and end symbol in a particular slot, MCS, and NDI, and the value of the K2 parameter. Additionally, the second scheduling grant indicates the SFI, which is used to denote whether a given symbol (e.g., OFDM symbol) in a slot is used for UL, DL, or flexible in the current TXOP. In particular, the SFI indicates a start of the UL burst. 
     At step  930 , the method  900  includes communicating, by the first wireless communication device with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. In scheme  500 , if the first wireless communication device corresponds to the BS, the uplink communication signal is received in accordance with the delay specified by SSI in the second UL scheduling grant. If the first wireless communication device corresponds to the UE, the uplink communication signal is transmitted in accordance with the delay specified by SSI in the second UL scheduling grant. In scheme  700 , if the first wireless communication device corresponds to the BS, the uplink communication signal is received in accordance with the delay specified in the first UL scheduling grant (e.g., value of K2) and the start of the UL burst specified by the SFI. If the first wireless communication device corresponds to the UE, the uplink communication signal is transmitted in accordance with the delay specified in the first UL scheduling grant (e.g., value of K2) and the start of the UL burst specified by the SFI. 
     As discussed, the delay between PDCCH and PUSCH without the two-stage grant technique may be long. The delay may be attributable to the time consumed for decoding PDCCH and preparing PDSCH, and may be as much as 700 microseconds (μs) for SCS of 15 KHz and 400 us for SCS of 30 KHz. With the two-stage grant technique, the delay between the second stage of the grant and PUSCH may be reduced to include only the time it takes to decode PDCCH. The delay, however, may still be substantial as the UE may perform blind decoding of PDCCH covering different aggregation levels, offsets, payload sizes, etc. The UE may perform blind decoding of the PDCCH payload as it is unaware of the detailed control channel structure, including the number of control channels and the number of control channel elements (CCEs) to which each control channel is mapped. Multiple PDCCHs may be transmitted in a single subframe, which may or may not be all relevant to a particular UE. The UE determines the PDCCH specific to it by monitoring a set of PDCCH candidates (a set of consecutive CCEs on which a PDCCH could be mapped) in every subframe. It may be desirable to reduce the delay between the second stage of the grant and the start of PUSCH. 
     In some examples, the delay between the second stage of the grant and the start of PUSCH may be reduced by reducing blind decoding attempts of the second PDCCH. In an example, the first UL scheduling grant includes an indication of a pre-configured reduced search space or blind decoding for the second PDCCH for finding the second UL scheduling grant. In this example, it is unnecessary for the UE to search the entire search space for the second UL scheduling grant, potentially saving time and processing cycles. Such an implementation may be more feasible if the second PDCCH is a group or cell trigger. Additionally, the first PDCCH included in the first UL scheduling grant may point to the blind decoding candidate (or candidates) for the second PDCCH. In an example, a linkage between the first PDCCH and the second PDCCH in terms of the blind decoding hypotheses may be implemented. Such an implementation may be more feasible when both the first PDCCH and the second PDCCH are UE specific. 
     In some examples, the delay between the second stage of the grant and the start of PUSCH may be reduced by providing a particular ordering for the PDCCH blind decoding such that the UE finds the second stage PDCCH faster even if the UE has not yet finished processing all the PDCCH blind decoding hypotheses. In an example, the first UL scheduling grant includes an indication of a particular ordering for a blind decoding for a second PDCCH for finding the second UL scheduling grant. The ordering may be pre-configured and/or determined based on parameters for the first PDCCH (e.g., aggregation level, offset, information in its payload, etc.). In an example, the delay between PDCCH and PUSCH may be a function of which blind decoding hypothesis has the second stage grant in this ordering. 
     In some examples, the delay between the second stage of the grant and the start of PUSCH may be reduced by providing a new signal that is quickly processed (e.g., e.g. wake up signal, preamble, etc.) rather than PDCCH, where the second stage grant is the new signal. In an example, a signal indicating a location of a second PDCCH for finding the second UL scheduling grant is communicated. 
     The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an 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, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). 
     The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive 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 (i.e., A and B and C). 
     Further embodiments of the present disclosure include a method of wireless communication, including communicating, by a first wireless communication device with a second wireless communication device, a first scheduling grant; communicating, by the first wireless communication device with the second wireless communication device, a second scheduling grant including at least one of a SSI or a SFI; and communicating, by the first wireless communication device with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     In some examples, the first wireless communication device is a BS, and the second wireless communication device is a UE. In some examples, communicating the first scheduling grant includes transmitting the first scheduling grant in a first TXOP, communicating the second scheduling grant includes transmitting the second scheduling grant in a second TXOP, and communicating the uplink communication signal includes receiving an uplink data packet in the second TXOP. In some examples, the first wireless communication device is a UE, and the second wireless communication device is a BS. In some examples, communicating the first scheduling grant includes receiving the first scheduling grant in a first TXOP, communicating the second scheduling grant includes receiving the second scheduling grant in a second TXOP, and communicating the uplink communication signal includes transmitting an uplink data packet in the second TXOP. 
     In some examples, the first scheduling grant is communicated during a first TXOP, and the second scheduling grant and the uplink communication signal are communicated during a second TXOP. In some examples, the first scheduling grant includes at least one of a RA, a start and end symbol for a slot, an MCS, or an NDI. In some examples, the second TXOP includes a plurality of slots, and the second scheduling grant includes a parameter indicating a slot at which to transmit the UL data. In some examples, the parameter is the SSI relative to transmission of the second scheduling grant. In some examples, the parameter is an unknown slot index included in the first scheduling grant. In some examples, the uplink communication signal includes an UL data packet, and the first scheduling grant includes an unknown slot index to indicate to the second wireless communication device to hold transmission of the communication signal. 
     In some examples, the first scheduling grant includes at least one of an RA, a start and end symbol for a slot, an MCS, an NDI, and a parameter indicating a timing delay of the communicating the uplink communication signal relative to a start of a set of flexible or UL symbols in the second TXOP. In some examples, the second scheduling grant triggers activation of the first scheduling grant. In some examples, the second TXOP includes a plurality of slots, and the second scheduling grant includes the SFI denoting whether a given symbol in a slot is used for an uplink, a downlink, or a flexible link direction. In some examples, communicating the first scheduling grant includes communicating an indication of a pre-configured reduced search space or blind decoding for a second PDCCH for finding the second UL scheduling grant. In some examples, communicating the first scheduling grant includes communicating an indication of a particular ordering for a blind decoding for a second PDCCH for finding the second UL scheduling grant. In some examples, the method also includes communicating a signal indicating a location of a second PDCCH for finding the second UL scheduling grant. 
     Further embodiments of the present disclosure include an apparatus including a transceiver configured to: communicate, with a second wireless communication device, a first scheduling grant; communicate, with the second wireless communication device, a second scheduling grant including at least one of a SSI or a SFI; and communicate, with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     In some examples, the second wireless communication device is a UE. In some examples, the second wireless communication device is a BS. In some examples, the transceiver is included in a UE. In some examples, the transceiver is included in a BS. In some examples, the first scheduling grant is included in a first TXOP, the second scheduling grant is included in a second TXOP, and the uplink communication signal includes an uplink data packet in the second TXOP. In some examples, the first scheduling grant includes at least one of a RA, a start and end symbol for a slot an, an MCS, or a NDI. In some examples, the second TXOP includes a plurality of slots, and the second scheduling grant includes a parameter indicating a slot at which to transmit the UL data. In some examples, the parameter is the SSI relative to transmission of the second scheduling grant. In some examples, the first scheduling grant includes at least one of an RA, a start and end symbol for a slot, an MCS, an NDI, and a parameter indicating a timing delay of the communicating the uplink communication signal relative to a start of a set of flexible or UL symbols in the second TXOP. In some examples, the second scheduling grant triggers activation of the first scheduling grant. In some examples, the second TXOP includes a plurality of slots, and the second scheduling grant includes the SFI denoting whether a given symbol in a slot is used for an uplink, a downlink, or a flexible link direction. 
     Further embodiments of the present disclosure include a computer-readable medium having program code recorded thereon, the program code including: code for causing a first wireless communication device to communicate, with a second wireless communication device, a first scheduling grant; code for causing the first wireless communication device to communicate, with a second wireless communication device, a second scheduling grant including at least one of a start slot index (SSI) or a slot format indicator (SFI); and code for causing the first wireless communication device to communicate, an uplink communication signal based on the first scheduling grant and the second scheduling grant. In some examples, the first wireless communication device is a BS, and the second wireless communication device is a UE. In some examples, the first wireless communication device is a UE, and the second wireless communication device is a BS. 
     Further embodiments of the present disclosure include an apparatus including means for communicating, with a second wireless communication device, a first scheduling grant; means for communicating, with a second wireless communication device, a second scheduling grant including at least one of a start slot index (SSI) or a slot format indicator (SFI); and means for communicating, with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant. 
     As those of some skill in this art will by now appreciate and depending on the particular application at hand, many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of use of the devices of the present disclosure without departing from the spirit and scope thereof. In light of this, the scope of the present disclosure should not be limited to that of the particular embodiments illustrated and described herein, as they are merely by way of some examples thereof, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.