WO2021195801A1

WO2021195801A1 - Multiple resources in channels for low latency communication in unlicensed band

Info

Publication number: WO2021195801A1
Application number: PCT/CN2020/081893
Authority: WO
Inventors: Changlong Xu; Jing Sun; Xiaoxia Zhang
Original assignee: Qualcomm Incorporated
Priority date: 2020-03-28
Filing date: 2020-03-28
Publication date: 2021-10-07

Abstract

Certain aspects of the present disclosure provide techniques for wireless communication. A method that may be performed by a user equipment (UE) includes receiving one or more grants scheduling resources on a plurality of first channels, the resources being scheduled for transmission of the same transport block (TB), determining whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and transmitting the TB using resources on the channel based on the determination.

Description

MULTIPLE RESOURCES IN CHANNELS FOR LOW LATENCY COMMUNICATION IN UNLICENSED BAND

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for low latency communication.

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These 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, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, 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, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 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 OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports 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 NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include reduced communicated latency.

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a user equipment (UE) . The method generally includes receiving one or more grants scheduling resources on a plurality of first channels, the resources being scheduled for transmission of the same transport block (TB) , determining whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and transmitting the TB using resources on the channel based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication. The method generally includes generating one or more grants scheduling resources on a plurality of first channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels, transmitting the one or more grants to a user-equipment (UE) , and receiving the TB on a channel of the plurality of channels in accordance with the one or more grants.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a user-equipment (UE) . The apparatus generally includes a memory, and one or more processors coupled to the memory, wherein the memory and the one or more processors are configured to receive one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) , determine whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and transmit the TB using resources on the channel based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes a memory, and one or more processors coupled to the memory, wherein the memory and the one or more processors are configured to generate one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels, transmit the one or more grants to a user-equipment (UE) , and receive the TB on a channel of the plurality of channels in accordance with the one or more grants.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a user-equipment (UE) . The apparatus generally includes means for receiving one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) , means for determining whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and means for transmitting the TB using resources on the channel based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes means for generating one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels, means for transmitting the one or more grants to a user-equipment (UE) , and means for receiving the TB on a channel of the plurality of channels in accordance with the one or more grants.

Certain aspects of the subject matter described in this disclosure can be implemented in computer-readable medium having instructions stored thereon to cause a user-equipment (UE) to receive one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) , determine whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and transmit the TB using resources on the channel based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in computer-readable medium having instructions stored thereon to cause an apparatus to generate one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels, transmit the one or more grants to a user-equipment (UE) , and receive the TB on a channel of the plurality of channels in accordance with the one or more grants.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which 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 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.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating a design of an example a base station (BS) and user equipment (UE) , in accordance with certain aspects of the present disclosure.

FIG. 3 is an example frame format for new radio (NR) , in accordance with certain aspects of the present disclosure.

FIGs. 4A and 5B illustrate a listen-before-talk (LBT) communication protocol, in accordance with certain aspects of the present disclosure.

FIG. 5 is a flow diagram illustrating example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure.

FIG. 6 is a flow diagram illustrating example operations for wireless communication by a BS, in accordance with certain aspects of the present disclosure.

FIGs. 7A, 7B, and 7C illustrate uplink (UL) grants for scheduling PUSCH resources in two channels, in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Certain aspects of the present disclosure provide techniques for improving uplink performance for URLLC in an unlicensed band. When communicating on an unlicensed band, listen-before-talk (LBT) operation may be performed prior to transmission. In certain aspects, resources on multiple channels may be scheduled for transmission of the same transport block (TB) , increasing the probability that LBT will be successful for at least one of the channels to transmit the TB, thereby reducing latency. In certain aspects, each of multiple channels may be configured with an index to indicate priorities associated with the channels. A UE may determine which of the channels is to be used for transmission of the TB if LBT is successful for multiple channels.

The following description provides examples of low latency transmission in communication systems, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, 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. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

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, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or new radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe. NR supports beamforming and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be an NR system (e.g., a 5G NR network) . As shown in FIG. 1, the wireless communication network 100 may be in communication with a core network 132. The core network 132 may in communication with one or more base station (BSs) 110 and/or user equipment (UE) 120 in the wireless communication network 100 via one or more interfaces.

As illustrated in FIG. 1, the wireless communication network 100 may include a number of BSs 110a-z (each also individually referred to herein as BS 110 or collectively as BSs 110) and other network entities. A BS 110 may provide communication coverage for a particular geographic area, sometimes referred to as a “cell” , which may be stationary or may move according to the location of a mobile BS 110. In some examples, the BSs 110 may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces (e.g., a direct physical connection, a wireless connection, a virtual network, or the like) using any suitable transport network. In the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the

femto cells

102y and 102z, respectively. A BS may support one or multiple cells. A network controller 130 may couple to a set of BSs 110 and provide coordination and control for these BSs 110 (e.g., via a backhaul) .

The BSs 110 communicate with UEs 120a-y (each also individually referred to herein as UE 120 or collectively as UEs 120) in the wireless communication network 100. The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. Wireless communication network 100 may also include relay stations (e.g., relay station 110r) , also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS 110a or a UE 120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE 120 or a BS 110) , or that relays transmissions between UEs 120, to facilitate communication between devices.

According to certain aspects, the BSs 110 and UEs 120 may be configured for data transmission with low latency. As shown in FIG. 1, the BS 110a includes a URLLC manager 112. The URLLC manager 112 may be configured to generate one or more grants scheduling resources on a plurality of first channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels, transmit the one or more grants to a user-equipment (UE) ; and receive the TB on a channel of the plurality of channels in accordance with the one or more grants, in accordance with aspects of the present disclosure. As shown in FIG. 1, the UE 120a includes a URLLC manager 122. The URLLC manager 122 may be configured to receive one or more grants scheduling resources on a plurality of first channels, the resources being scheduled for transmission of the same TB, determine whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and transmit the TB using resources on the channel based on the determination, in accordance with aspects of the present disclosure.

FIG. 2 illustrates example components of BS 110a and UE 120a (e.g., in the wireless communication network 100 of FIG. 1) , which may be used to implement aspects of the present disclosure.

At the BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. A medium access control (MAC) -control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH) , a physical uplink shared channel (PUSCH) , or a physical sidelink shared channel (PSSCH) .

The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , and channel state information reference signal (CSI-RS) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a-232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120a, a transmit processor 264 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 262 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators in transceivers 254a-254r (e.g., for SC-FDM, etc. ) , and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas 234, processed by the modulators 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 the UE 120a. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The

memories

242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Antennas 252,

processors

266, 258, 264, and/or controller/processor 280 of the UE 120a and/or antennas 234,

processors

220, 230, 238, and/or controller/processor 240 of the BS 110a may be used to perform the various techniques and methods described herein. For example, as shown in FIG. 2, the controller/processor 240 of the BS 110a has a URLLC manager 241 that may be configured for low latency communication in an unlicensed band, according to aspects described herein. As shown in FIG. 2, the controller/processor 280 of the UE 120a has a URLLC manager 281 that may be configured for low latency communication in an unlicensed band, according to aspects described herein. Although shown at the controller/processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

NR may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. NR may support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may be dependent on the system bandwidth. The minimum resource allocation, called a resource block (RB) , may be 12 consecutive subcarriers. The system bandwidth may also be partitioned into subbands. For example, a subband may cover multiple RBs. NR may support a base subcarrier spacing (SCS) of 15 KHz and other SCS may be defined with respect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. ) .

FIG. 3 is a diagram showing an example of a frame format 300 for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots (e.g., 1, 2, 4, 8, 16, …slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the SCS. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols) . Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.

Listen-Before-Talk (LBT) is a feature that allows for fair coexistence of wireless nodes. For example, a transmitter may first sense a medium and transmit a message if the medium is sensed to be idle. As an example, an uplink (UL) data channel (e.g., physical uplink shared channel (PUSCH) ) transmission may be performed based on an UL grant transmission via a downlink control channel. The UL grant may be transmitted by a base station (BS) . After receiving the UL grant, a scheduled UE may check to see if the medium is clear, and if so, then the UE may transmit on the uplink data channel after a contention window (CW) . The CW may span a certain number of slots selected randomly within a contention window size (CWS) spanning between a minimum CW setting CWmin and a maximum CW setting CWmax. Thus, each node that may occupy a medium may begin transmitting at a random time interval. If a transmission by a node is unsuccessful due to a collision between transmissions of two nodes, the CWS may be increased to reduce the chances of collision during a subsequence transmission opportunity.

Example Listen-Before-Talk (LBT) Protocol

FIGs. 4A and 4B illustrates a CW for a category-4 (CAT-4) LBT, in some aspects. As illustrated, after a channel busy period 402, a transmitter (e.g., transmitter 440 as illustrated in FIG. 4B) may begin a defer period during which the node defers any transmission. The defer period may include a defer duration of 16us, plus one or more defer time intervals (Td) , as illustrated in FIG. 4A. For example, a quantity of n defer time intervals (Td) may be implemented, n being related to a channel access priority class (CAPC) of the node, and the typical value for Td may be 9us. After the defer duration (16us and n Td) CW 406 begins. The CW 406 may have a duration of N x Td, N being a randomly selected integer uniformly distributed between 0 and a contention window size (CWS) . The CWS may be updated using feedback on a channel, as described in more detail herein. Channels without explicit feedback may use the CWS last updated by channels with explicit feedback and may use the same CAPC if such channels exist. Otherwise, such channels may use the minimum CWS (CWSmin) corresponding to the CAPC. As illustrated, a transmission 408 may occur after the CW 406. The transmission 408 may be PDSCH or PUSCH.

For CWS adjustment for transmissions including PDSCH and PUSCH, if HARQ feedback is available relative to a prior CW update, the feedback for the latest channel occupancy time (COT) for which new feedback is received may be used for CWS adjustment. For example, if a receiver 442 transmits HARQ feedback 420 in response to receiving data transmission 408 from transmitter 440, as illustrated in FIG. 4B, and the HARQ feedback 420 is acknowledge (ACK) indicating that the transmission 408 was successfully decoded, the transmitter 440 may set the CWS to a minimum CW setting (CWmin) at block 422. However, if the HARQ feedback 420 is negative ACK (NACK) indicating that the transmission was not successfully decoded, or in absence of feedback within a feedback window in which case the transmitter (e.g., BS or UE) retransmits the TB, CWS may be set to the minimum of CW × 2 + 1 or a maximum CW setting (CWmax) . In other words, if a data transmission is determined to be unsuccessful, transmitter 440 may adjust (increase) the CWS at block 422, reducing the chances of collision of transmission by different nodes. As illustrated in FIG. 4B, another data transmission 424 may occur after another CW associated with the adjusted CWS.

The feedback window (e.g., during which HARQ feedback 420 may be received) starts at the end of a reference duration and has a duration of maximum of X ms or the duration of the transmission burst from start of the reference duration + 1 ms. If the absence of other technologies in the medium cannot be guaranteed, X may be equal to 5 ms, and X may be equal to 10 ms otherwise. If a new HARQ feedback is not available, the CW may remain the same. As used herein, HARQ feedback may include any implicit methods of HARQ feedback determination.

Example Techniques for Low Latency Communication

5G NR in unlicensed spectrum (NR-U) provides technology for cellular operators to integrate the unlicensed spectrum into 5G networks. NR-U enables both uplink and downlink operation in unlicensed bands. In NR-U, channel access in both downlink and uplink rely on a listen-before-talk (LBT) feature. A wireless device or a base station may first sense ongoing communications on a channel to determine whether there is communications on the channel prior to any transmission to avoid interference. When a communication channel is a wide bandwidth unlicensed carrier, the channel sensing procedure relies on detecting energy level on multiple bands of the communication channel.

In both Enhanced Licensed Assisted Access (eLAA) and NR-U, UL transmission with a Cat-4 LBT protocol may be upgrade to Cat-2 LBT protocol. The Cat-2 LBT protocol may be a 25us LBT protocol having a lower latency than the Cat-4 LBT protocol. The UE may be initially scheduled outside the base station’s (e.g., eNB or gNB) acquired channel occupancy time (COT) with Cat-4 LBT. For example, downlink control information (DCI) may be used to indicate that Cat-4 LBT is to be used for transmission on a physical uplink shared channel (PUSCH) where the UL transmission is K2 slots later than the DCI. A few slots before the UE’s transmission, the BS may attempt to perform Cat-4 LBT, and transmits COT-SI if the LBT is successful. If the UE detects the COT-SI, then the UE may switch to Cat-2 LBT for the UL transmission within the UL duration of the BS’s COT. If the UE does not detect the COT-SI, the UE continues with Cat-4 LBT. In some cases, the UE may choose to not switch to Cat-2 LBT even if DL COT-SI is detected.

In both eLAA and NR-U, a UE may support a multi-channel LBT procedure. For example, if a scheduled bandwidth is larger than 20 MHz, the bandwidth may be divided into several subbands (also referred to herein as channels) . The UE may randomly select one of a set of channels to perform Cat-4 LBT and the UE may perform Cat-2 LBT for the rest of channels if certain conditions are satisfied. The conditions being that the UE is scheduled or configured to transmit on the set of channels, the UL grant (s) indicate Cat-4 LBT and the same PUSCH starting position across the set of channels or UL transmissions are configured to start transmissions at the same time for all channels, and that the set of carriers are grouped in conformance to WiFi channel bonding rules. In each carrier, the UL transmission may be allowed only if the LBTs of all subbands pass. As used herein, a channel may be used to denote either LBT subband or carrier.

There are various designs for URLLC in a licensed band. To achieve ultra-reliability and low latency for URLLC, the impact of LBT may be considered for the unlicensed band. Cat-4 LBT may in delay. LBT failure makes the latency for communication even worse. Certain aspects of the present disclosure provide techniques for improving uplink performance for URLLC in an unlicensed band by considering the impact of LBT. For example, resources for multiple channels may be scheduled for transmission of the same transport block (TB) , increasing the probability that LBT will be successful for at least one of the channels to transmit the TB. In certain aspects, each of multiple channels may be configured with an index (e.g., also referred to as an “order” ) to indicate priorities associated with the channels. A UE may determine which of the channels is to be used for transmission of the TB if LBT is successful for multiple channels.

FIG. 5 is a flow diagram illustrating example operations 500 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 500 may be performed, for example, by a BS (e.g., such as the BS 110a in the wireless communication network 100) .

Operations 500 may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor 240 of FIG. 2) . Further, the transmission and reception of signals by the BS in operations 500 may be enabled, for example, by one or more antennas (e.g., antennas 234 of FIG. 2) . In certain aspects, the transmission and/or reception of signals by the BS may be implemented via a bus interface of one or more processors (e.g., controller/processor 240) obtaining and/or outputting signals.

The operations 500 may begin, at block 505, by generating one or more grants scheduling resources (e.g., also referred to as PUSCH resources) on a plurality of first channels. The resources may be scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels. At block 510, the BS may transmit the one or more grants to a user-equipment (UE) , and at block 515, receive the TB on a channel of the plurality of channels in accordance with the one or more grants.

FIG. 6 is a flow diagram illustrating example operations 600 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 600 may be performed, for example, by UE (e.g., such as a UE 120a in the wireless communication network 100) . The operations 600 may be complimentary operations by the UE to the operations 500 performed by the BS. Operations 600 may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor 280 of FIG. 2) . Further, the transmission and reception of signals by the UE in operations 600 may be enabled, for example, by one or more antennas (e.g., antennas 252 of FIG. 2) . In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor 280) obtaining and/or outputting signals.

The operations 600 may begin, at block 605, by the UE receiving one or more grants scheduling resources (e.g., also referred to as PUSCH resources) on a plurality of first channels, the resources being scheduled for transmission of the same transport block (TB) . At block 610, the UE determines whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels, and at block 615, transmits the TB using resources on the channel based on the determination.

For example, multiple PUSCH resources for a single transport block (TB) may be scheduled in multiple channels (e.g., LBT subbands) with the resource in one channel being designated to deal with LBT failure issues. The resources may be sorted in increasing order. For example, the resource on the channel having an order with a minimum value (e.g., the lowest order as compared to the orders of all the scheduled resources across the channels) may be considered as the primary resource. The UE may determine which resource to use for transmission of the TB based on the orders. For example, if only one of the channels (e.g., LBT subbands) pass LBT operation, the UE may transmit the TB on the channel which passes LBT operation. If two or more channels pass LBT operation, the UE transmits the TB on the channel with the lower order index among the channels with successful LBT operation. If no channel passes LBT operation, the UE may not transmit the TB.

Certain aspects of the present disclosure are directed to techniques for signaling channel (e.g., LBT subband) order. In certain aspects, the orders may be radio resource control (RRC) configured. For example, an RRC message may be used to configure the channels (e.g., LBT subbands) with predefined orders for URLLC transmission.

In certain aspects, the orders may be explicitly indicated by adding additional bits in DCI. For example, a bit in DCI may indicate that a corresponding resource being scheduled by the DCI is a primary resource or a secondary resource. In some cases, multiple bits may be used indicate orders associated with more than two resources in respective channels for the same TB.

In certain aspects, a special combinations of information fields in DCI may be used to indicate the orders of the channels. For example, DCIs carrying the grants for the resources may include a modulation and coding scheme (MCS) level field. If two resources are scheduled in two channels, a normal MCS level value may indicate that the associated resource in a corresponding channel is a primary resource. An MCS level value with a special value may indicate that the associated resource in a corresponding channel is a secondary resource. When a UE receives two UL-grants for URLLC, if all the fields except the MCS level and frequency resource (e.g., corresponding to the different LBT subbands) are the same and one MCS level value is a special value as predefined, the UE may determine that the two resources are allocated for a single TB, and that the UL-grant in DCI indicating the normal value for the MCS level is for the primary resource. The UE may be preconfigured to determine what value of the MCS level field in DCI is a special value and what values are normal values.

FIGs. 7A, 7B, and 7C illustrate UL grants for scheduling PUSCH resources in two channels (e.g., LBT subbands) , in accordance with certain aspects of the present disclosure. As illustrated, the UL grant 702 schedules a resource for the PUSCH 706 and the UL grant 704 schedules a resource for the PUSCH 708. In other words, the two UL grants schedule two PUSCH resources for URLLC with each PUSCH in one LBT subband. All the fields in the UL grants 702, 704 may be the same, except the MCS level field and frequency resource, as described herein. In other words, the UL grant 702 may indicate the frequency resource associated with LBT subband 0 (also referred to as LBT bandwidth (BW) 0) , and the UL grant 702 may indicate the frequency resource associated with LBT subband 1 (also referred to as LBT BW 1) .

As described herein, the values of the MCS level field that are considered to be a special value and a normal value may be preconfigured at the UE. The UL grant 702 may have an MCS field with a normal value and the UL grant 704 may have an MCS field with a special MCS value. Therefore, the resource for PUSCH 706 in LBT subband 0 may be designated as the primary resource.

As illustrated in FIG. 7A,

LBT operations

710, 712 may be performed on each of the LBT subbands prior to transmission of the TB via the scheduled resources. The LBT operation 710 for LBT subband 0 may be successful, and the LBT operation 712 for the LBT subband 1 may fail. In this case, the UE transmits the TB over PUSCH 706 in LBT subband 0. As illustrated in FIG. 7B, the LBT operation 710 for LBT subband 0 may be successful, and the LBT operation 712 for the LBT subband 1 may be successful. In this case, the UE transmits the TB over PUSCH 706 in LBT subband 0 because the resource for PUSCH 706 is a primary resource and the resource for PUSCH 708 is a secondary resource. As illustrated in FIG. 7C, the LBT operation 710 for LBT subband 0 may fail, and the LBT operation 712 for the LBT subband 1 may be successful. In this case, even though the resource for PUSCH 708 is a secondary resource, the UE transmits the TB over PUSCH 708 in LBT subband 1 because the LBT operation 710 for LBT subband 0 has failed. While the examples provided in FIGs. 7A, 7B, and 7C are described using an LBT subband to facilitate understanding, the aspects described herein are applicable to transmissions across any type of channels such as carrier carriers (CCs) .

Certain aspects of the present disclosure are directed to carrier aggregation (CA) in an unlicensed band. For multiple LBT subbands, as long as the resource scheduled by multiple URLLC UL-grants are in the same time region within different LBT subbands, the UE may determine that the multiple PUSCH resources are for a single TB. However, the scheduling of multiple carriers for CA may be separately operated. In other words, various parameters such as hybrid automatic request (HARQ) -incremental redundancy (IR) process ID or bandwidth may not be the same for each component carrier (CC) . Thus, the BS may indicate to the UE whether resources in different CCs are for the same TB. For instance, whether multiple resources in different CCs are configured for a single TB may be explicitly indicated by one or more bits in DCI, or implicitly indicated by some combination of information fields in DCI. Moreover, for CA, the BS may indicate to the UE the order of the carriers. For example, the carrier order may be RRC configured. In other words, an RRC message may indicate the order for the carriers, allowing the UE to determine which carrier to use for transmission of the TB in case multiple carriers pass LBT operation.

FIG. 8 illustrates a communications device 800 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIGs. 5 and 6. The communications device 800 includes a processing system 802 coupled to a transceiver 808 (e.g., a transmitter and/or a receiver) . The transceiver 808 is configured to transmit and receive signals for the communications device 800 via an antenna 810, such as the various signals as described herein. The processing system 802 may be configured to perform processing functions for the communications device 800, including processing signals received and/or to be transmitted by the communications device 800.

The processing system 802 includes a processor 804 coupled to a computer-readable medium/memory 812 via a bus 806. In certain aspects, the computer-readable medium/memory 812 is configured to store instructions (e.g., computer-executable code) that when executed by the processor 804, cause the processor 804 to perform the operations illustrated in FIGs. 5 and 6, or other operations for performing the various techniques discussed herein for low latency communication in an unlicensed band. In certain aspects, computer-readable medium/memory 812 stores code 814 for receiving/transmitting; code 816 for determining; code 818 for performing LBT; and code 819 for generating. In certain aspects, the processor 804 has circuitry configured to implement the code stored in the computer-readable medium/memory 812. The processor 804 includes circuitry 821 for receiving/transmitting; circuitry 820 for determining; circuitry 822 for performing LBT; and circuitry 824 for generating.

The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR) , 3GPP Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single-carrier frequency division multiple access (SC-FDMA) , time division synchronous code division multiple access (TD-SCDMA) , and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . LTE and LTE-Aare releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . NR is an emerging wireless communications technology under development.

In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and BS, next generation NodeB (gNB or gNodeB) , access point (AP) , distributed unit (DU) , carrier, or transmission reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. 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 an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . 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.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, 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 computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, 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) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, 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, which may be narrowband IoT (NB-IoT) devices.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , 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 commercially available 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, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read- Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, for example, instructions for performing the operations described herein and illustrated in FIGs. 5 and 6.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

A method for wireless communication by a user-equipment (UE) , comprising:

receiving one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) ;

determining whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels; and

transmitting the TB using resources on the channel based on the determination.
The method of claim 1, wherein the one or more grants comprises a grant for each of the channels.
The method of claim 1, further comprising:

receiving an indication of an order associated with each of the plurality of channels; and

determining the channel of the plurality of channels on which the TB is to be transmitted based on the order associated with each of the plurality of channels.
The method of claim 3, wherein the determination of the channel on which the TB is to be transmitted comprises selecting as the channel one of the plurality of channels having the lowest order.
The method of claim 3, wherein receiving the indication of the order associated with each of the plurality of channels comprises receiving an radio resource control (RRC) message indicating the orders.
The method of claim 3, wherein receiving the indication of the order associated with each of the plurality of channels comprises receiving one or more downlink control information (DCI) indicating the orders.
The method of claim 3, wherein the one or more grants comprises a grant for each of the plurality of channels carried in downlink control information (DCI) , and wherein one or more fields of the DCI indicates the order associated with a corresponding one of the plurality of channels.
The method of claim 7, wherein the one or more fields comprise a modulation and coding scheme (MCS) field of the DCI.
The method of claim 1, wherein the one or more grants comprises a grant for each of the plurality of channels, the method further comprising determining that the resources on the plurality of channels are scheduled for transmission of the same TB based on one or more fields of each of the grants for the plurality of channels having the same value.
The method of claim 1, wherein the one or more grants is carried in at least one DCI, and wherein the method further comprises determining that the resources on the plurality of channels are scheduled for transmission of the same TB based on one or more bits of the at least one DCI.
The method of claim 1, wherein the one or more grants is carried in at least one DCI, and wherein the method further comprises determining that the resources on the plurality of channels are scheduled for transmission of the same TB based on one or more information fields of the at least one DCI.
The method of claim 1, wherein the plurality of channels comprise a plurality of component carriers for carrier aggregation (CA) .
The method of claim 1, wherein the plurality of channels comprise a plurality of subbands.
A method for wireless communication, comprising:

generating one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels;

transmitting the one or more grants to a user-equipment (UE) ; and

receiving the TB on a channel of the plurality of channels in accordance with the one or more grants.
The method of claim 14, wherein the one or more grants comprises a grant for each of the channels.
The method of claim 14, further comprising transmitting an indication of an order associated with each of the plurality of channels to be used for determining the channel of the plurality of channels on which the TB is to be transmitted.
The method of claim 16, wherein the channel on which the TB is transmitted is the channel having the lowest order across the plurality of channels.
The method of claim 16, wherein transmitting the indication of the order associated with each of the plurality of channels comprises transmitting an radio resource control (RRC) message indicating the orders.
The method of claim 16, wherein transmitting the indication of the order associated with each of the plurality of channels comprises transmitting one or more downlink control information (DCI) indicating the orders.
The method of claim 16, wherein the one or more grants comprises a grant for each of the plurality of channels carried in downlink control information (DCI) , and wherein one or more fields of the DCI indicates the order associated with a corresponding one of the plurality of channels.
The method of claim 20, wherein the one or more fields comprise a modulation and coding scheme (MCS) field of the DCI.
The method of claim 14, wherein the one or more grants comprises a grant for each of the plurality of channels, and wherein one or more fields of each of the grants for the plurality of channels having the same value if the resources on the plurality of channels are scheduled for transmission of the same TB.
The method of claim 14, wherein the one or more grants is carried in at least one DCI, and wherein on one or more bits of the at least one DCI indicate that the resources on the plurality of channels are scheduled for transmission of the same TB.
The method of claim 14, wherein the one or more grants is carried in at least one DCI, and wherein one or more information fields of the at least one DCI indicate that the resources on the plurality of channels are scheduled for transmission of the same TB.
The method of claim 14, wherein the plurality of channels comprise a plurality of component carriers for carrier aggregation (CA) .
The method of claim 14, wherein the plurality of channels comprise a plurality of subbands.
An apparatus for wireless communication by a user-equipment (UE) , comprising:

a memory; and

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

receive one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) ;

determine whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels; and

transmit the TB using resources on the channel based on the determination.
An apparatus for wireless communication, comprising:

a memory; and

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

generate one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels;

transmit the one or more grants to a user-equipment (UE) ; and

receive the TB on a channel of the plurality of channels in accordance with the one or more grants.
An apparatus for wireless communication by a user-equipment (UE) , comprising:

means for receiving one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) ;

means for determining whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels; and

means for transmitting the TB using resources on the channel based on the determination.
An apparatus for wireless communication, comprising:

means for generating one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels;

means for transmitting the one or more grants to a user-equipment (UE) ; and

means for receiving the TB on a channel of the plurality of channels in accordance with the one or more grants.
A computer-readable medium having instructions stored thereon to cause a user-equipment (UE) to:

receive one or more grants scheduling resources on a plurality of channels, the resources being scheduled for transmission of the same transport block (TB) ;

determine whether to transmit the TB on a channel of the plurality of channels by performing listen-before-talk (LBT) operation on each of the plurality of channels; and

transmit the TB using resources on the channel based on the determination.
A computer-readable medium having instructions stored thereon to cause an apparatus to:

generate one or more grants scheduling resources on a plurality of channels, wherein the resources are scheduled for transmission of the same transport block (TB) after listen-before-talk (LBT) operation is performed on each of the plurality of channels;

transmit the one or more grants to a user-equipment (UE) ; and

receive the TB on a channel of the plurality of channels in accordance with the one or more grants.