WO2021159442A1

WO2021159442A1 - Channel access enchancement for a fixed frame mode for unlicensed spectrum

Info

Publication number: WO2021159442A1
Application number: PCT/CN2020/075206
Authority: WO
Inventors: Changlong Xu; Jing Sun; Xiaoxia Zhang
Original assignee: Qualcomm Incorporated
Priority date: 2020-02-14
Filing date: 2020-02-14
Publication date: 2021-08-19

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may monitor for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP; and transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time. Numerous other aspects are provided.

Description

CHANNEL ACCESS ENCHANCEMENT FOR A FIXED FRAME MODE FOR UNLICENSED SPECTRUM

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for channel access enhancement for a fixed frame mode for unlicensed spectrum.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and/or the like) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) . A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New Radio (NR) , which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP) . NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a user equipment (UE) , may include monitoring for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, and transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time.

In some aspects, a method of wireless communication, performed by a UE, may include monitoring for a COT indicator at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, and monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP. The method may include transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time.

In some aspects, a method of wireless communication, performed by a base station, may include performing a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, and performing a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.

In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to monitor for a COT indicator from a base station at a first time in an FFP of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, and transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time.

In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to monitor for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, monitor for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP, and transmit uplink data in the FFP based at least in part on receiving the COT indicator at the second time.

In some aspects, a base station for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to perform a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, and perform a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to monitor for a COT indicator from a base station at a first time in an FFP of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, and transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to monitor for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, monitor for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP, and transmit uplink data in the FFP based at least in part on receiving the COT indicator at the second time.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, may cause the one or more processors to perform a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, and perform a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.

In some aspects, an apparatus for wireless communication may include means for monitoring for a COT indicator from a base station at a first time in an FFP of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, and means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time.

In some aspects, an apparatus for wireless communication may include means for monitoring for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, means for monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP, and means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time.

In some aspects, an apparatus for wireless communication may include means for performing a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, and means for performing a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is a block diagram conceptually illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 2 is a block diagram conceptually illustrating an example of a base station in communication with a UE in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 3 illustrates an example of fixed frame periods (FFPs) , in accordance with various aspects of the present disclosure.

Fig. 4 illustrates an example of a Cat-4 listen before talk (LBT) procedure, in accordance with various aspects of the present disclosure.

Fig. 5 illustrates an example of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 6 illustrates an example of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 7 illustrates an example of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 8 illustrates an example of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 9 illustrates an example of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 10 is a diagram illustrating an example process performed, for example, by a UE, in accordance with various aspects of the present disclosure.

Fig. 11 is a diagram illustrating an example process performed, for example, by a UE, in accordance with various aspects of the present disclosure.

Fig. 12 is a diagram illustrating an example process performed, for example, by a base station, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

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

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Fig. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in Fig. 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some aspects, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Fig. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. In some aspects, macro BSs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 Watts) .

A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like. A UE may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, in some aspects, robots, drones, remote devices, sensors, meters, monitors, location tags, and/or the like, that may communicate with a base station, another device (e.g., remote device) , or some other entity. A wireless node may provide, in some aspects, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE) . UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like. In some aspects, the processor components and the memory components may be coupled together. In some aspects, the processor components (e.g., one or more processors) and the memory components (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, electrically coupled, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a base station 110 as an intermediary to communicate with one another) . In some aspects, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like) , a mesh network, and/or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the base station 110.

As indicated above, Fig. 1 is provided as an example. Other examples may differ from what is described with regard to Fig. 1.

Fig. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

At base station 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS (s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , reference signal received quality (RSRQ) , channel quality indicator (CQI) , and/or the like. In some aspects, one or more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110. At base station 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240. Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with channel access enhancement for a fixed frame mode for unlicensed spectrum, as described in more detail elsewhere herein. Frame based equipment (FBE) mode may be an example of such a mode. In some aspects, controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, in some aspects, process 1000 of Fig. 10, process 1100 of Fig. 11, process 1200 of Fig. 12, and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. In some aspects, memory 242 and/or memory 282 may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. In some aspects, the one or more instructions, when executed (e.g., directly, or after compiling, converting, interpreting, and/or the like) by one or more processors of the base station 110 and/or the UE 120, may perform or direct operations of, in some aspects, process 1000 of Fig. 10, process 1100 of Fig. 11, process 1200 of Fig. 12, and/or other processes as described herein. In some aspects, executing instructions may include running the instructions, converting the instructions, compiling the instructions, interpreting the instructions, and/or the like. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for monitoring for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time, and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2, such as controller/processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and/or the like.

In some aspects, UE 120 may include means for monitoring for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, means for monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP, means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time, and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2, such as controller/processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and/or the like.

In some aspects, base station 110 may include means for performing a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, means for performing a second LBT procedure of a second LBT type in a first part of the FFP based, and/or the like. In some aspects, such means may include one or more components of base station 110 described in connection with Fig. 2, such as antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller/processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, antenna 234, and/or the like.

As indicated above, Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.

Transmissions on unlicensed carriers may require a TRP, such as a UE or base station (e.g., gNB) , to determine whether a carrier (frequency channel) is clear for transmission. Listen Before Talk (or Listen Before Transmit) (LBT) is a mechanism that the TRP may use to determine whether a channel is clear (clear channel assessment) . If the TRP performs LBT on a channel and the channel is clear, this may be called an LBT success. If the TRP performs LBT on the channel and the channel is not clear, this may be called an LBT failure.

Fig. 3 illustrates an example 300 of FFPs, in accordance with various aspects of the present disclosure.

FBE mode is an example of a mode of communication that includes FFPs for communicating in unlicensed spectrum. As shown in Fig. 3, an FFP, used by a TRP (e.g., gNB) , may have a channel occupancy time (COT) portion for transmitting downlink communications. The gNB may share the COT portion with a UE for receiving uplink communications. The FFP may have an idle period at an end of the FFP, after the COT portion, for performing an LBT procedure for the next FFP. The FFP may be 1 millisecond (ms) , 2 ms, 2.5 ms, 4 ms, 5 ms, 10 ms, and/or the like (including the idle period) . Starting positions of the FFPs within every two radio frames (e.g., even radio frames) may be given by i *P where i = {0, 1, ... , 20/P-1} and P is the FFP in ms. The idle period for a given subcarrier spacing (SCS) may be a ceiling value for a minimum idle period allowed by regulations divided by Ts, where the minimum idle period allowed = max (5%of FFP, 100 microseconds (μs) ) , and Ts is a symbol duration for the given SCS. The idle period may have no less than 5%of the FFP.

An FFP configuration for FBE may be included in a system information block (e.g., SIB-1) or signaled in UE-specific radio resource control (RRC) signaling. If the network indicates FBE operation for fallback downlink and uplink grants, for an indication of LBT type of Cat-2 (25 μs) or Cat-4, the UE may follow the mechanism whereby one 9 μs slot (e.g., one shot LBT) is measured within a 25 μs interval. UE transmissions within the FFP may occur if downlink signals or channels, such as a physical downlink control channel (PDCCH) , a synchronization signal block, a physical broadcast channel, remaining minimum system information, a group common PDCCH, and/or the like, within the FFP are detected. A same 2-bit field in load based equipment (LBE) mode may be used or reinterpreted to indicate an FBE LBT type, a cyclic prefix extension, and/or a channel access priority class indication.

In Release 16 NR unlicensed (NR-U) , only a base station (e.g., gNB) can act as an initiating device, and the UE may only act as a responding device. The channel access rules may thus be as follows. If the gNB initiates COT, Cat-1 LBT may not apply and the gNB may perform Cat-2 LBT right before an FFP. If the gNB is to transmit a downlink burst in gNB COT, the gNB may perform Cat-1 LBT if a gap from a previous downlink or uplink burst is within 16 μs, and perform Cat-2 LBT if the gap is more than 16 μs. If the UE initiates COT, Cat-1 LBT and Cat-2 LBT may not apply. If the UE is to transmit an uplink burst in a gNB COT, the UE may perform Cat-1 LBT if the gap is within 16 μs, and perform Cat-2 LBT if the gap is greater than 16 μs. Note that the Cat-2 LBT for FBE may be different from Cat-2 LBT (25 μs or 16 μs) in LBE. In some aspects, one 9 μs measurement right before the transmission may be needed, with at least 4 μs for measurement.

As indicated above, Fig. 3 is provided as an example. Other examples may differ from what is described with regard to Fig. 3.

Unlicensed frequency spectrum may be used for ultra-reliable low-latency communication (URLLC) and industrial IoT applications that involve a controlled environment. A controlled environment may be an environment that is controlled such that there will be no other RAT or other operators operating in the coverage area. An LBT procedure may thus always pass, even if performed for an FBE device. More generally, even though a factory owner or operator can clear the environment, there may still be a chance that some other RAT is operating.

Load based equipment (LBE) mode is another mode for communicating in unlicensed spectrum. LBE mode involves LBT procedures, but does not require a fixed periodic structure and is thus more flexible. LBE does not require uplink signals to be transmitted at a beginning of an FFP, and LBE does not require a TRP to detect downlink control signals before transmitting on the uplink. However, cross-link interference between TRPs in the same neighborhood may block some LBE mode transmissions and cause LBT failures.

Fig. 4 illustrates an example 400 of a Cat-4 LBT, in accordance with various aspects of the present disclosure.

Cat-4 LBT is a type of LBT procedure that a TRP may use when there is potential congestion. After a channel is detected as busy, there may be a defer period (e.g., 16 μs) before LBT signal detection begins again. The time before detection may be lengthened by additional time duration (Td) periods. This additional time may be defined as n *Td, where n is related to a channel access priority class (CAPC) , and Td may typically be 9 μs. High priority transmissions may have fewer time durations, and low priority transmissions may have more time durations. The defer period and additional time durations may run before a contention window begins. Detection on the channel may occur during the contention window. If a threshold level of a signal is not detected on the channel, transmission may proceed on the channel. The contention window may be a time duration of N *Td, where random number N may be uniformly distributed between 0 and a contention window size. Fig. 4 shows an example where n = 3 and N = 5.

Contention window adjustment is a mechanism in LBE for a TRP to back off on contention for a channel when there is potential congestion. When congestion is detected, the contention window doubles (up to a maximum) , and when there is no congestion, the contention window resets to a minimum size. The contention window adjustment may be driven by decoding errors, which may be used as an approximation for collision events.

As indicated above, Fig. 4 is provided as an example. Other examples may differ from what is described with regard to Fig. 4.

A gNB that contends for access to a channel may perform an LBT procedure prior to a start of an FFP. The gNB may perform the procedure in an idle period at an end of a previous FFP. If the LBT procedure by the gNB fails, there may be no downlink transmissions in the FFP. There may also be no uplink transmissions in the FFP, because a UE may not transmit uplink data if the UE does not detect any downlink control signals for the FFP. The FFP may go unused and this results in high latency that is not acceptable for some devices, such as URLLC devices. Throughput may also be reduced as FFP resources are wasted.

According to some aspects described herein, a channel access mechanism may be enhanced for a fixed frame mode for unlicensed spectrum (e.g., FBE mode) . If a first LBT procedure on a channel for an FFP fails, the gNB may still obtain the channel during a remaining portion of the FFP. The gNB may perform a second LBT procedure (and even a third LBT procedure) for the same FFP. As a result, there is an increased chance that the FFP may still be used after the first LBT procedure fails. The gNB and a corresponding UE may avoid wasting resources and increasing latency.

Fig. 5 illustrates an example 500 of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure. Fig. 5 shows a base station (BS) 510 (e.g., BS 110 depicted in Figs. 1 and 2) and a UE 520 (e.g., UE 120 depicted in Figs. 1 and 2) that may communicate with each other.

As shown by reference number 530, BS 510 may perform a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum. In some aspects, the first LBT type may be a Cat-2 LBT. BS 510 may determine that the first LBT procedure failed. As shown by reference number 535, BS 510 may perform a second LBT procedure of a second LBT type in a first part of the FFP, based at least in part on the determination that the first LBT procedure of the first LBT type failed. In some aspects, the second LBT type may be a Cat-4 LBT.

As shown by reference number 540, UE 520 may receive a COT indicator from BS 510 at a first time, based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP. UE 520 may have expected a COT indicator at the earlier time, which may be a start time or a first part of the FFP. Normally, UE 520 may abandon trying to transmit data altogether after not receiving the COT indicator at the earlier time. However, UE 520 may continue to monitor for (e.g., be prepared to receive and process) a COT indicator. The UE 520 may be configured to monitor for a COT indicator at another time in the FFP, such as at the first time. As shown by reference number 545, UE 520 may transmit data in the FFP based at least in part on receiving the COT indicator at the first time.

As indicated above, Fig. 5 is provided as an example. Other examples may differ from what is described with regard to Fig. 5.

Fig. 6 illustrates an example 600 of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure. Fig. 6 shows a gNB that may correspond to BS 510 depicted in Fig. 5.

As shown by Fig. 6, a first LBT procedure by a gNB on a channel for an FFP may be a Cat-2 LBT, and the second LBT procedure, if the Cat-2 LBT procedure fails, may be a different LBT type, such as a Cat-4 LBT. The gNB may perform the Cat-2 LBT just prior to the FFP, such as in an idle period at an end of a previous FFP. If the Cat-2 LBT passes, the gNB occupies the channel, and the gNB transmits a COT indicator to a UE. If the Cat-2 LBT procedure fails, the gNB may perform a Cat-4 LBT procedure. When a contention window of the Cat-4 LBT procedure counts down to zero, the gNB may transmit data in the FFP up to an idle period of the FFP. The gNB may also transmit a COT indicator to the UE. Note that a time duration for Cat-4 LBT may be longer than a time duration for Cat-2 LBT. While Cat-2 LBT and Cat-4 LBT are shown in Fig. 6, other types of LBT may be used for the first LBT procedure and/or the second LBT procedure.

As indicated above, Fig. 6 is provided as an example. Other examples may differ from what is described with regard to Fig. 6.

Fig. 7 illustrates an example 700 of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure. Fig. 7 shows a BS 710 (e.g., BS 110 depicted in Figs. 1 and 2, BS 510 depicted in Fig. 5, the gNB depicted in Fig. 6, and/or the like) and a UE 720 (e.g., UE 120 depicted in Figs. 1 and 2, UE 520 depicted in Fig. 5, and/or the like) that may communicate with each other.

As shown by reference number 730, BS 710 may perform a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum. In some aspects, the first LBT type may be a Cat-2 LBT. BS 710 may determine that the first LBT procedure failed. As shown by reference number 735, BS 710 may perform a second LBT procedure of a second LBT type in a first part of the FFP, based at least in part on the determination that the first LBT procedure of the first LBT type failed. In some aspects, the second LBT type may be a Cat-2 LBT, a Cat-4 LBT, or another LBT type.

As shown by reference number 740, UE 720 may monitor for a COT indicator from BS 710 at a first time, based at least in part on a determination that a COT indicator was not received at an earlier time in the FFP. UE 720 may have expected a COT indicator at the earlier time, which may be a start time or a first part of the FFP, but UE 720 may continue to monitor for a COT indicator. UE 720 may be configured to monitor for a COT indicator at another time in the FFP, such as at the first time.

As shown by reference number 745, BS 710 may perform a third LBT procedure of a third LBT type at a second time in the FFP, based at least in part on a determination that the second LBT procedure of the second LBT type failed. As shown by reference number 750, UE 720 may monitor for a COT indicator from BS 710 at a second time, based at least in part on a determination that a COT indicator was not received at the first time in the FFP. As shown by reference number 755, UE 720 may receive the COT indicator at the second time. As shown by reference number 760, UE 720 may transmit data in the FFP based at least in part on receiving the COT indicator at the second time.

As indicated above, Fig. 7 is provided as an example. Other examples may differ from what is described with regard to Fig. 7.

Fig. 8 illustrates an example 800 of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure. Fig. 8 shows a gNB that may correspond to BS 710 depicted in Fig. 7.

Fig. 8 shows multiple starting points in an FFP for the gNB to attempt transmission on a channel. At each starting point, the gNB may perform an LBT procedure. If the LBT procedure fails, the gNB may perform an LBT procedure at a next starting point. Some communication modes, such as FBE mode, may need to be adjusted to allow for multiple starting points in the FFP, while keeping the FFP structure (e.g., fixed period with an idle period) .

Fig. 8 shows the gNB performing a Cat-2 LBT procedure on a channel before a start of the FFP. This Cat-2 LBT procedure may be performed in an idle period at an end of a previous FFP. If the Cat-2 LBT procedure passes, the gNB may occupy the channel. If the Cat-2 LBT fails, the gNB may perform another LBT procedure, such as another Cat-2 LBT procedure. If this additional Cat-2 LBT procedure fails, the gNB may perform a third LBT procedure, such as another Cat-2 LBT procedure.

If the third LBT procedure fails, the gNB may perform a fourth LBT procedure or may determine that enough channel access attempts have been made in the FFP. If the third LBT procedure passes, the gNB may transmit downlink data and transmit a COT indicator to a UE. The gNB may then receive uplink data. Starting times for these LBT procedures, and/or expected receive times for a UE monitoring for a COT indicator, may be pre-configured by radio resource control messages or downlink control information messages. In some aspects, a gap between each starting time may be more than 25 μs but much less than an idle period min (100 μs, 5%of FFP) .

As indicated above, Fig. 8 is provided as an example. Other examples may differ from what is described with regard to Fig. 8.

Fig. 9 illustrates an example 900 of channel access enhancement for a fixed frame mode for unlicensed spectrum, in accordance with various aspects of the present disclosure.

Fig. 9 shows a timeline of multiple consecutive FFPs. In some aspects, if an initial LBT procedure prior to or at a start of a current FFP fails, the current FFP may be available for other LBT procedures or for preparing for later FFPs. For example, an idle period is normally found at an end of an FFP. If a current FFP is available for other operations, at least part of an idle period for a subsequent FFP may be effectively shifted earlier into the current FFP. For example, as shown in Fig, 9, an idle period, or a least a portion of an idle period for subsequent FFP0 may be shifted into the current FFP. The shifted idle period may be in a first part of the current FFP. The gNB may perform an LBT procedure for a subsequent FFP1 or make other preparations for FFP1 in the current FFP. Because part of the idle period for FFP0 is effectively shifted into the current FFP, the idle period in FFP0 may be reduced. This provides for a larger COT portion in FFP0 for data transmissions. In some aspects, the gNB may perform different types of LBT procedures, such as a Cat-4 LBT procedure, in the current FFP for other FFPs. The gNB may use available time in the current FFP for other subsequent FFPs, such as an idle period for FFP1 that pertains to an even later FFP.

In some aspects, although some of an idle period at an end of FFP0 is shifted into the current FFP, there may be a remaining portion of the idle period that remains at the end of FFP0 such that an LBT procedure, such as a one-shot LBT procedure, may be performed, if necessary. As a result of shifting idle periods for later FFPs into the current FFP, some resources in the current FFP may not be wasted due to one or more initial LBT failures for the current FFP.

As indicated above, Fig. 9 is provided as an example. Other examples may differ from what is described with regard to Fig. 9.

Fig. 10 is a diagram illustrating an example process 1000 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 1000 is an example where the UE (e.g., UE 120 depicted in Figs. 1 and 2, UE 520 depicted in Fig. 5, UE 720 depicted in Fig. 7, and/or the like) performs operations associated with channel access enhancement for a fixed frame mode for unlicensed spectrum.

As shown in Fig. 10, in some aspects, process 1000 may include monitoring for a COT indicator from a base station at a first time in an FFP of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP (block 1010) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may monitor for a COT indicator from a base station at a first time in an FFP of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP, as described above.

As further shown in Fig. 10, in some aspects, process 1000 may include transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time (block 1020) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time, as described above.

Process 1000 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the earlier time is at a start of the FFP, and the first time is a time duration after the start of the FFP.

In a second aspect, alone or in combination with the first aspect, the time duration is based at least in part on an LBT duration for the base station to perform an LBT procedure.

In a third aspect, alone or in combination with one or more of the first and second aspects, the LBT procedure is a Cat-4 LBT.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the LBT procedure is a Cat-2 LBT.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process 1000 includes receiving information associated with the LBT procedure, determining the LBT duration based at least in part on the information associated with the LBT procedure, and monitoring for the COT indicator from the base station at the first time based at least in part on the LBT duration.

Although Fig. 10 shows example blocks of process 1000, in some aspects, process 1000 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 10. Additionally, or alternatively, two or more of the blocks of process 1000 may be performed in parallel.

Fig. 11 is a diagram illustrating an example process 1100 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 1100 is an example where the UE (e.g., UE 120 depicted in Figs. 1 and 2, UE 520 depicted in Fig. 5, UE 720 depicted in Fig. 7, and/or the like) performs operations associated with channel access enhancement for a fixed frame mode for unlicensed spectrum.

As shown in Fig. 11, in some aspects, process 1100 may include monitoring for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP (block 1110) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may monitor for a COT indicator at a first time in an FFP of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP, as described above.

As further shown in Fig. 11, in some aspects, process 1100 may include monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP (block 1120) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may monitor for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP, as described above.

As further shown in Fig. 11, in some aspects, process 1100 may include transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time (block 1130) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may transmit uplink data in the FFP based at least in part on receiving the COT indicator at the second time, as described above.

Process 1100 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, process 1100 includes receiving an indication of the first time and the second time in one of a radio resource configuration message or a downlink control information message.

In a second aspect, alone or in combination with the first aspect, process 1100 includes determining the first time and the second time from stored configuration information.

Although Fig. 11 shows example blocks of process 1100, in some aspects, process 1100 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 11. Additionally, or alternatively, two or more of the blocks of process 1100 may be performed in parallel.

Fig. 12 is a diagram illustrating an example process 1200 performed, for example, by a base station, in accordance with various aspects of the present disclosure. Example process 1200 is an example where the base station (e.g., BS 110 depicted in Figs. 1 and 2, BS 510 depicted in Fig. 5, the gNB depicted in Figs. 6 and 8, BS 710 depicted in Fig. 7, and/or the like) performs operations associated with channel access enhancement for a fixed frame mode for unlicensed spectrum.

As shown in Fig. 12, in some aspects, process 1200 may include performing a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum (block 1210) . For example, the base station (e.g., using transmit processor 220, receive processor 238, controller/processor 240, memory 242, and/or the like) may perform a first LBT procedure of a first LBT type prior to an FFP in a fixed frame mode for unlicensed spectrum, as described above.

As further shown in Fig. 12, in some aspects, process 1200 may include performing a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed (block 1220) . For example, the base station (e.g., using transmit processor 220, receive processor 238, controller/processor 240, memory 242, and/or the like) may perform a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed, as described above.

Process 1200 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the first LBT type is different than the second LBT type.

In a second aspect, alone or in combination with the first aspect, the first LBT type is Cat-2 LBT, and the second LBT type is Cat-4 LBT.

In a third aspect, alone or in combination with one or more of the first and second aspects, process 1200 includes transmitting a COT indicator to a UE based at least in part on a determination that the second LBT procedure is successful.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 1200 includes performing a third LBT procedure of a third LBT type in the FFP based at least in part on a determination that the second LBT procedure failed.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process 1200 includes determining a first time of the FFP for the second LBT procedure and a second time of the FFP for the third LBT procedure based at least in part on stored configuration information.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the FFP is a first FFP, and the second LBT procedure corresponds to a COT in a second FFP that is subsequent to the first FFP.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process 1200 includes reducing a time for an idle period for the second FFP at an end of the first FFP.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process 1200 includes performing a third LBT procedure in the first FFP that corresponds to a COT in a third FFP that is subsequent to the second FFP.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, process 1200 includes reducing a time for an idle period for the third FFP at an end of the second FFP.

Although Fig. 12 shows example blocks of process 1200, in some aspects, process 1200 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 12. Additionally, or alternatively, two or more of the blocks of process 1200 may be performed in parallel.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set.

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication performed by a user equipment (UE) , comprising:

monitoring for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP; and

transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time.
The method of claim 1, wherein the earlier time is at a start of the FFP, and the first time is a time duration after the start of the FFP.
The method of claim 2, wherein the time duration is based at least in part on a listen before talk (LBT) duration for the base station to perform an LBT procedure.
The method of claim 3, wherein the LBT procedure is a Cat-4 LBT.
The method of claim 3, wherein the LBT procedure is a Cat-2 LBT.
The method of claim 3, further comprising:

receiving information associated with the LBT procedure;

determining the LBT duration based at least in part on the information associated with the LBT procedure; and

monitoring for the COT indicator from the base station at the first time based at least in part on the LBT duration.
A method of wireless communication performed by a user equipment (UE) , comprising:

monitoring for a channel occupancy time (COT) indicator at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP;

monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP; and

transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time.
The method of claim 7, further comprising receiving an indication of the first time and the second time in one of a radio resource configuration message or a downlink control information message.
The method of claim 7, further comprising determining the first time and the second time from stored configuration information.
A method of wireless communication performed by a base station, comprising:

performing a first listen before talk (LBT) procedure of a first LBT type prior to a fixed frame period (FFP) in a fixed frame mode for unlicensed spectrum; and

performing a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.
The method of claim 10, wherein the first LBT type is different than the second LBT type.
The method of claim 11, wherein the first LBT type is Cat-2 LBT, and the second LBT type is Cat-4 LBT.
The method of claim 10, further comprising transmitting a channel occupancy time (COT) indicator to a user equipment (UE) based at least in part on a determination that the second LBT procedure is successful.
The method of claim 10, further comprising performing a third LBT procedure of a third LBT type in the FFP based at least in part on a determination that the second LBT procedure failed.
The method of claim 14, further comprising determining a first time of the FFP for the second LBT procedure and a second time of the FFP for the third LBT procedure based at least in part on stored configuration information.
The method of claim 10, wherein the FFP is a first FFP, and wherein the second LBT procedure corresponds to a COT in a second FFP that is subsequent to the first FFP.
The method of claim 16, further comprising reducing a time for an idle period for the second FFP at an end of the first FFP.
The method of claim 16, further comprising performing a third LBT procedure in the first FFP that corresponds to a COT in a third FFP that is subsequent to the second FFP.
The method of claim 18, further comprising reducing a time for an idle period for the third FFP at an end of the second FFP.
A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

monitor for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP; and

transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time.
A user equipment (UE) for wireless communication, comprising:a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

monitor for a channel occupancy time (COT) indicator at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP;

monitor for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP; and

transmit uplink data in the FFP based at least in part on receiving the COT indicator at the second time.
A base station for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

perform a first listen before talk (LBT) procedure of a first LBT type prior to a fixed frame period (FFP) in a fixed frame mode for unlicensed spectrum; and

perform a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment (UE) , cause the one or more processors to:

monitor for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP; and

transmit uplink data in the FFP based at least in part on receiving the COT indicator at the first time.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment (UE) , cause the one or more processors to:

monitor for a channel occupancy time (COT) indicator at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP;

monitor for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP; and

transmit uplink data in the FFP based at least in part on receiving the COT indicator at the second time.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a base station, cause the one or more processors to:

perform a first listen before talk (LBT) procedure of a first LBT type prior to a fixed frame period (FFP) in a fixed frame mode for unlicensed spectrum; and

perform a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.
An apparatus for wireless communication, comprising:

means for monitoring for a channel occupancy time (COT) indicator from a base station at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum, based at least in part on a determination that the COT indicator is not received at an earlier time in the FFP; and

means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the first time.
An apparatus for wireless communication, comprising:

means for monitoring for a channel occupancy time (COT) indicator at a first time in a fixed frame period (FFP) of a fixed frame mode for unlicensed spectrum based at least in part on a determination that the COT indicator was not received at an earlier time in the FFP;

means for monitoring for the COT indicator at a second time in the FFP based at least in part on a determination that the COT indicator was not received at the first time in the FFP; and

means for transmitting uplink data in the FFP based at least in part on receiving the COT indicator at the second time.
An apparatus for wireless communication, comprising:

means for performing a first listen before talk (LBT) procedure of a first LBT type prior to a fixed frame period (FFP) in a fixed frame mode for unlicensed spectrum; and

means for performing a second LBT procedure of a second LBT type in a first part of the FFP based at least in part on a determination that the first LBT procedure of the first LBT type failed.