Patent Description:
Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for sensing and transmitting multiple transport blocks for New Radio sidelink.

"Downlink" or "forward link" refers to the communication link from the BS to the UE, and "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, or a <NUM> Node B.

However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE, NR, and other radio access technologies.

<CIT> discloses a UE that can be requested to select sidelink resource for transmission based on both decoding SA (scheduling assignment) and LBT (listen before talk)-type channel sensing. The UE may first decode all the SA transmitted from other UEs in certain slots and, based on the decoded SAs, the UE can find all the sidelink subchannels in these slots that has been reserved by other UEs. Then, the UE can choose one or more subchannels from the remaining subchannels as candidate resource selection. The UE performs per-subchannel (or called per-subband) LBT for those selected subchannel(s). If the LBT passes, the UE can begin to transmit on the selected subchannel(s) until the last slots in which the selected subchannel(s) is not reserved by other UEs.

In some aspects, a method of wireless communication performed by a user equipment (UE) includes determining candidate resources on one or more physical sidelink shared channels (PSSCHs) that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to listen-before-talk (LBT) completion instants for the at least two transport blocks. The method includes selecting, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks, wherein the transmit resources have no gap between each other, such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel. The method also includes transmitting the at least two transport blocks in the transmit resources.

In some aspects, a UE for wireless communication includes a memory and one or more processors coupled to the memory, the one or more processors configured to determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks. The one or more processors are configured to select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks, wherein the transmit resources have no gap between each other, such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel, and transmit the at least two transport blocks in the transmit resources.

In some non-claimed aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks, select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel, and transmit the at least two transport blocks in the transmit resources.

In some non claimed aspects, an apparatus for wireless communication includes means for determining candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks, means for selecting, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel, and means for transmitting the at least two transport blocks in the transmit resources.

The invention relates to a user equipment and method as claimed.

<FIG> is a diagram illustrating an example of a wireless network <NUM> in accordance with the present disclosure. A base station (BS) is an entity that communicates with user equipment (UEs) and may also be referred to as an NR BS, a Node B, a gNB, a <NUM> node B (NB), an access point, or a transmit receive point (TRP).

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 <NUM> through various types of backhaul interfaces such as a direct physical connection, or a virtual network using any suitable transport network.

A relay BS may also be referred to as a relay station, a relay base station, or a relay.

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, such as macro BSs, pico BSs, femto BSs, and/or relay BSs.

MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, and/or location tags that may communicate with a base station, another device (e.g., remote device), or some other entity.

A RAT may also be referred to as a radio technology, and/or an air interface. A frequency may also be referred to as a carrier, and/or a frequency channel.

For example, the UEs <NUM> 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-pedestrian (V2P) protocol, or a vehicle-to-infrastructure (V2I) protocol), and/or a mesh network.

Transmit processor <NUM> may also process system information (e.g., for semi-static resource partitioning information (SRPI)) and control information (e.g., CQI requests, grants, upper layer signaling) and provide overhead symbols and control symbols. Transmit processor <NUM> may also generate reference symbols for reference signals (e.g., a cell-specific reference signal (CRS), a demodulation reference signal (DMRS)) and synchronization signals (e.g., the primary synchronization signal (PSS) or a secondary synchronization signal (SSS)).

A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and/or CQI, among other examples.

The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM), and transmitted to base station <NUM>. The transceiver may be used by a processor (e.g., controller/processor <NUM>) and memory <NUM> to perform aspects of any of the methods described herein (for example, as described with reference to <FIG>).

The transceiver may be used by a processor (e.g., controller/processor <NUM>) and memory <NUM> to perform aspects of any of the methods described herein (for example, as described with reference to <FIG>).

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with sensing and transmitting multiple transport blocks for NR sidelink, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and/or program code) for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, and/or interpreting) by one or more processors of base station <NUM> and/or UE <NUM>, may cause the one or more processors, UE <NUM>, and/or base station <NUM> to perform or direct operations of, for example, process <NUM> of <FIG>, and/or other processes as described herein. In some aspects, executing instructions may include running the instructions, converting the instructions, compiling the instructions, and/or interpreting the instructions, among other examples.

In some aspects, UE <NUM> may include means for determining candidate resources on one or more physical sidelink shared channels (PSSCHs) that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to listen-before-talk (LBT) completion instants for the at least two transport blocks, means for selecting, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel, and/or means for transmitting the at least two transport blocks in the transmit resources. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of sidelink communications, in accordance with the present disclosure.

As shown in <FIG>, a first UE <NUM>-<NUM> may communicate with a second UE <NUM>-<NUM> (and one or more other UEs <NUM>) via one or more sidelink channels <NUM>. The UEs <NUM>-<NUM> and <NUM>-<NUM> may communicate using the one or more sidelink channels <NUM> for P2P communications, D2D communications, V2X communications (e.g., which may include V2V communications, V2I communications, V2P communications, and/or the like), mesh networking, and/or the like. In some aspects, the UEs <NUM> (e.g., UE <NUM>-<NUM> and/or UE <NUM>-<NUM>) may correspond to one or more other UEs described elsewhere herein, such as UE <NUM>. In some aspects, the one or more sidelink channels <NUM> may use a PC5 interface and/or may operate in a high frequency band (e.g., the <NUM> band). Additionally, or alternatively, the UEs <NUM> may synchronize timing of transmission time intervals (TTIs) (e.g., frames, subframes, slots, symbols, and/or the like) using global navigation satellite system (GNSS) timing.

As further shown in <FIG>, the one or more sidelink channels <NUM> may include a physical sidelink control channel (PSCCH) <NUM>, a PSSCH <NUM>, and/or a physical sidelink feedback channel (PSFCH) <NUM>. The PSCCH <NUM> may be used to communicate control information, similar to a physical downlink control channel (PDCCH) and/or a physical uplink control channel (PUCCH) used for cellular communications with a base station <NUM> via an access link or an access channel. The PSSCH <NUM> may be used to communicate data, similar to a physical downlink shared channel (PDSCH) and/or a physical uplink shared channel (PUSCH) used for cellular communications with a base station <NUM> via an access link or an access channel. For example, the PSCCH <NUM> may carry sidelink control information (SCI) <NUM>, which may indicate various control information used for sidelink communications, such as one or more resources (e.g., time resources, frequency resources, spatial resources, and/or the like) where a transport block (TB) <NUM> may be carried on the PSSCH <NUM>. The TB <NUM> may include data. The PSFCH <NUM> may be used to communicate sidelink feedback <NUM>, such as hybrid automatic repeat request (HARQ) feedback (e.g., acknowledgement or negative acknowledgement (ACK/NACK) information), transmit power control (TPC), and/or a scheduling request (SR).

In some aspects, the one or more sidelink channels <NUM> may use resource pools. For example, a scheduling assignment (e.g., included in SCI <NUM>) may be transmitted in subchannels using specific resource blocks (RBs) across time. In some aspects, data transmissions (e.g., on the PSSCH <NUM>) associated with a scheduling assignment may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, a scheduling assignment and associated data transmissions are not transmitted on adjacent RBs.

In some aspects, a UE <NUM> may operate using a transmission mode where resource selection and/or scheduling is performed by the UE <NUM> (e.g., rather than a base station <NUM>). In some aspects, the UE <NUM> may perform resource selection and/or scheduling by sensing channel availability for transmissions. For example, the UE <NUM> may measure an RSSI parameter (e.g., a sidelink-RSSI (S-RSSI) parameter) associated with various sidelink channels, may measure an RSRP parameter (e.g., a PSSCH-RSRP parameter) associated with various sidelink channels, may measure an RSRQ parameter (e.g., a PSSCH-RSRQ parameter) associated with various sidelink channels and may select a channel for transmission of a sidelink communication based at least in part on the measurement(s).

Additionally, or alternatively, the UE <NUM> may perform resource selection and/or scheduling using SCI <NUM> received in the PSCCH <NUM>, which may indicate occupied resources, and/or channel parameters. Additionally, or alternatively, the UE <NUM> may perform resource selection and/or scheduling by determining a channel busy rate/ratio (CBR) associated with various sidelink channels, which may be used for rate control (e.g., by indicating a maximum number of resource blocks that the UE <NUM> can use for a particular set of subframes).

In the transmission mode where resource selection and/or scheduling is performed by a UE <NUM>, the UE <NUM> may generate sidelink grants, and may transmit the grants in SCI <NUM>. A sidelink grant may indicate, for example, one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks to be used for the upcoming sidelink transmission on the PSSCH <NUM> (e.g., for TBs <NUM>), one or more subframes to be used for the upcoming sidelink transmission, and/or an MCS to be used for the upcoming sidelink transmission. In some aspects, a UE <NUM> may generate a sidelink grant that indicates one or more parameters for semi-persistent scheduling (SPS), such as a periodicity of a sidelink transmission. Additionally, or alternatively, the UE <NUM> may generate a sidelink grant for event-driven scheduling, such as for an on-demand sidelink message.

<FIG> is a diagram illustrating an example <NUM> of sidelink communications and access link communications, in accordance with the present disclosure.

As shown in <FIG>, a transmitter (Tx)/receiver (Rx) UE <NUM> and an Rx/Tx UE <NUM> may communicate with one another via a sidelink, as described above in connection with <FIG>. As further shown, in some sidelink modes, a base station <NUM> may communicate with the Tx/Rx UE <NUM> via a first access link. Additionally, or alternatively, in some sidelink modes, the base station <NUM> may communicate with the Rx/Tx UE <NUM> via a second access link. The Tx/Rx UE <NUM> and/or the Rx/Tx UE <NUM> may correspond to one or more UEs described elsewhere herein, such as the UE <NUM> of <FIG>. Thus, a direct link between UEs <NUM> (e.g., via a PC5 interface) may be referred to as a sidelink, and a direct link between a base station <NUM> and a UE <NUM> (e.g., via a Uu interface) may be referred to as an access link. Sidelink communications may be transmitted via the sidelink, and access link communications may be transmitted via the access link. An access link communication may be either a downlink communication (from a base station <NUM> to a UE <NUM>) or an uplink communication (from a UE <NUM> to a base station <NUM>).

<FIG> is a diagram illustrating an example <NUM> of a slot format, in accordance with the present disclosure. As shown in <FIG>, time-frequency resources in a radio access network may be partitioned into resource blocks, shown by a single RB <NUM>. An RB <NUM> is sometimes referred to as a physical resource block (PRB). An RB <NUM> includes a set of subcarriers (e.g., <NUM> subcarriers) and a set of symbols (e.g., <NUM> symbols) that are schedulable by a base station <NUM> as a unit. In some aspects, an RB <NUM> may include a set of subcarriers in a single slot. As shown, a single time-frequency resource included in an RB <NUM> may be referred to as a resource element (RE) <NUM>. An RE <NUM> may include a single subcarrier (e.g., in frequency) and a single symbol (e.g., in time). A symbol may be referred to as an orthogonal frequency division multiplexing (OFDM) symbol. An RE <NUM> may be used to transmit one modulated symbol, which may be a real value or a complex value.

In some telecommunication systems (e.g., NR), RBs <NUM> may span <NUM> subcarriers with a subcarrier spacing of, for example, <NUM> kilohertz (kHz), <NUM>, <NUM>, or <NUM>, among other examples, over a <NUM> millisecond (ms) duration. A radio frame may include <NUM> slots and may have a length of <NUM>. However, a slot length may vary depending on a numerology used to communicate (e.g., a subcarrier spacing, a cyclic prefix format). A slot may be configured with a link direction (e.g., downlink or uplink) for transmission. In some aspects, the link direction for a slot may be dynamically configured.

NR sidelink may be used for various applications, such as V2X peer-to-peer safety messages. NR sidelink may involve two channel access modes. Mode <NUM> is for deployment within coverage of a base station (e.g., gNB), where a sidelink transmitter (e.g., UE) receives grants from the gNB for sidelink channel access. Mode <NUM> is for autonomous deployment, where a sidelink transmitter uses channel sensing to access a sidelink channel. A sidelink transmitter may transmit SCI for transmitting a transport block on one or two PSSCHs. A transmit resource, which may include a subchannel in a slot (e.g., symbol, frame slot) may be reserved for transmitting the transport block. Reserving the resource may involve autonomous sensing, or sensing as determined by the UE.

NR sidelink may support other network topologies, such as a hub UE serving as a traffic source for multiple peripheral UEs. Such topologies may have nodes that do not use licensed spectrum. NR sidelink may be used in a <NUM>/<NUM> unlicensed band, and a UE may perform an LBT procedure to make sure a sidelink subchannel is clear before a transport block is transmitted on the sidelink subchannel. If a subchannel is not clear, there may be an LBT counter that backs off use of the subchannel, and the LBT counter may count down by slots or by time. The UE may not transmit a transport block on the subchannel until after an LBT countdown has been completed. The UE may estimate an LBT completion time and begin a resource selection window (future slots for selected transmit resources) based at least in part on the estimated LBT completion time.

<FIG> is a diagram illustrating examples <NUM>, <NUM> of autonomous sensing, in accordance with the present disclosure. Example <NUM> shows a timeline of a sensing window for sensing subchannels up to a resource selection trigger at time n for starting selection of resources inside a resource selection window. A beginning of the sensing window up to time n includes a time duration T<NUM>. There are two time durations Tproc,<NUM> and T<NUM> that allow for processing. A time T<NUM> for resource selection follows time n, and a length of T<NUM> may depend on a remaining packet delay budget (PDB).

When a resource selection is triggered at time n, a physical (PHY) layer of a UE examines the sensing window to determine a set of candidate resources for the upcoming resource selection window. The PHY layer may report the set of candidate resources to a medium access control (MAC) layer of the UE. The MAC layer may randomly select a transmit resource from the set of candidate resources for transmitting a transport block (e.g., MAC protocol data unit). The MAC layer may also randomly select (or reserve) later transmit resources for HARQ retransmissions of the transport block, one at a time, on one or more PSSCHs.

Mode <NUM> sidelink transmission may involve continuously sensing a channel up to a specified minimum time T<NUM> before actual transmission of a transport block on a selected transmit resource. This may include at least a second sensing of a transmit resource, and the second sensing may be referred to as a "last-minute" reevaluation of the transmit resource. A UE (MAC layer) may request a PHY layer to update candidate resources at this time, to double check whether a coming transmit resource and other reserved transmit resources are still clear. The PHY layer may respond to the MAC layer with a set of candidate resources that are available (still clear). If the coming transmit resource is no longer clear, the PHY layer may set a reselection flag for the MAC layer, which may reselect a transmit resource from among the newly provided candidate resources. This may lead to a new T<NUM> based reevaluation. Otherwise, the PHY layer expects to transmit the transport block on the selected transmit resource.

As indicated above, <FIG> provides some examples.

<FIG> is a diagram illustrating an example <NUM> of selecting transmit resources for two transport blocks, in accordance with the present disclosure. Example <NUM> shows reserved transmit resources for a first transport block (TB1) and a second transport block (TB2).

A UE may select a transmit resource for a single transport block based at least in part on an LBT completion time, but if there are multiple transport blocks, there can be an increase in latency. For example, TB <NUM> and TB2 may arrive at the MAC layer of a UE at slot n, and the UE (MAC layer) may select subchannels on a sidelink channel at slots m and m+<NUM> as transmit resources for TB1 and TB2, respectively. However, due to the random selection that normally occurs, there are empty slots between the transmit resources. The empty slots may cause the UE to perform a second LBT procedure, which consumes extra time and processing resources. The extra time and resources may become more prominent with a heavier traffic load.

<FIG> is a diagram illustrating an example <NUM> of sensing and transmitting multiple transport blocks for NR sidelink, in accordance with the present disclosure. <FIG> shows representations of a MAC layer and a PHY layer of a UE <NUM> (e.g., a UE <NUM> depicted in <FIG> and <FIG>).

According to various aspects described herein, a UE, when using an unlicensed band for sidelink, may sense subchannels of one or more PSSCHs and select transmit resources such that at least two transport blocks are transmitted in separate subchannels of the same slot in a frequency division multiplexing (FDM) fashion. In some aspects, the UE may select transmit resources such that transport blocks are transmitted in contiguous slots of the same subchannel. Either way, there is no gap between transmit resources that could cause the UE to perform a second LBT procedure. As a result, the UE conserves time, power, and processing resources that would otherwise be consumed by a second LBT procedure.

As shown by reference number <NUM>, the MAC layer of UE <NUM> may send a request for candidate resources to the PHY layer of UE <NUM>. The MAC layer may indicate a quantity of transport blocks for which resources are requested and/or any LBT completion instants for subchannels.

As shown by reference number <NUM>, the PHY layer may sense the subchannels and determine which candidate resources (subchannel and slot) are clear. The PHY layer may indicate the candidate resources to the MAC layer, as shown by reference number <NUM>. The MAC layer may select transmit resources from among the candidate resources for transmitting transport blocks, as shown by reference number <NUM>. The MAC layer may also reserve resources for retransmission.

In some aspects, there may be a "last-minute" reevaluation (second sensing) of the transmit resources to confirm that the transmit resources are still clear. If so, the UE (MAC and PHY layers) may transmit the transport blocks on the transmit resources, as shown by reference number <NUM>. Note that this second sensing is a quick channel occupancy time check and not a full LBT procedure with a backoff countdown.

<FIG> is a diagram illustrating examples <NUM>, <NUM> of sensing and transmitting multiple transport blocks for NR sidelink, in accordance with the present disclosure.

A UE may perform joint sensing for a quantity of transport blocks for up to the same quantity of sidelink subchannels. A MAC layer of the UE may obtain LBT completion instants for when an LBT backoff countdown is to be completed for respective subchannels. The quantity of LBT completion instants may be up to the quantity of transport blocks to be transmitted (and the quantity of subchannels). The MAC layer may send a sensing request to the PHY layer ahead of a resource selection window that will start no earlier than slot m, where a timing of slot m depends on the LBT completion instants. The sensing request may be for using a channel with enough subchannels for the transport blocks (N subchannels for N transport blocks).

The MAC layer may randomly select, from PSSCH candidate resources returned from the PHY layer, a transmit resource for a first transport block, where the transmit resource may be in a slot with multiple available subchannels. The MAC layer may then select other subchannels of the same slot as transmit resources for other transport blocks, such that the transport blocks are arranged in the same slot for FDM. Example <NUM> shows an example of transmit resources that are selected for TB1 and TB2 in the same slot for FDM. This purposeful placement of TB1 and TB2 is in contrast to a random selection of transmit resources that would normally occur for TB1 and TB2, which could create a gap between slots for TB1 and TB2.

Diverging from strict random selection may also allow for a "last-minute" selection of a transmit resource in the same slot. Example <NUM> shows that a transmit resource is selected for TB <NUM> that arrives at slot n. TB2 may have arrived late at slot n', but due to a "last-minute" reevaluation for TB1, a candidate resource is known to be clear in the same slot as the transmit resource for TB <NUM>. Therefore, the UE may select the transmit resource for late arrival TB2 to be in the same slot as TB <NUM>, thus preventing TB2 having to wait for a much later slot and undergoing another LBT procedure. In some aspects, the transmit resource for TB2 may be in a subsequent adjacent slot, so as to be placed with TB <NUM> in back-to-back slots in a time division multiplexing (TDM) fashion.

In some aspects, the UE may determine parameters for sensing and selecting transmit resources from stored configuration information, a system information block (SIB), and/or a radio resource control (RRC) message. For example, N may have a set maximum, or N may be limited as a function of a CBR, so that N decreases if subchannels tend to be busier. In some aspects, to avoid collisions, a greater value of N may shift slot m later in time. In some aspects, the UE (MAC layer) may specify priorities (e.g., low, median, mean, same, high) for transport blocks in the sensing request. The MAC layer may select transmit resources first for higher priority transport blocks.

In some aspects, the MAC layer may send a sensing request to the PHY layer for a quantity of subchannels that is based at least in part on a greatest common divisor of a quantity of subchannels that may be available for transport blocks. In other words, if the MAC layer is screening for two transport blocks, the PHY layer may return candidate resources in slots that have at least two clear subchannels. In some aspects, the sensing request may ask for resources that are at least a specified amount (e.g., percentage) of a resource selection window (e.g., greater than <NUM>%). In some aspects, the MAC layer may filter or screen candidate resources for slots that have at least the same quantity of clear subchannels as transport blocks to be submitted. Example <NUM> shows that slots <NUM>, <NUM>, and <NUM>, from among five slots of candidate resources, have at least two clear subchannels. The MAC layer may randomly select transmit resources from slots <NUM>, <NUM>, and <NUM>. As shown in <FIG>, the MAC layer may randomly select slot <NUM> for transmit resources for the two transport blocks.

In some aspects, the MAC layer may specify in a sensing request, or may screen for, a slot with contiguous subchannels that are clear. Example <NUM> shows that slot <NUM> has at least two contiguous clear subchannels. Therefore, the MAC layer may select two of the three clear subchannels in slot <NUM> as transmit resources for the two transport blocks.

<FIG> is a diagram illustrating examples <NUM>, <NUM>, <NUM> of sensing and transmitting multiple transport blocks for NR sidelink, in accordance with the present disclosure.

In some aspects, the UE (MAC layer) may be aware of an existing reserved resource when selecting transmit resources. The reserved resource may be reserved for a retransmission of a transport block. The MAC layer may cluster other transmit resources around the reserved resource. Clustering around the reserved resource may reduce a need to perform another LBT procedure. Example <NUM> shows a reserved resource in slot <NUM>. The MAC layer may select slot <NUM> and select transmit resources on either side of the reserved resource in slot <NUM>, such that transmit resources in slot <NUM> are arranged for FDM. In some aspects, the MAC layer may select a transmit resource in slot <NUM> that is in the same subchannel as the reserved resource, such that transmit resources in the subchannel are arranged in back-to-back TDM fashion. In some aspects, transmit resource selection that is aware of reserved resources may be configured (e.g., via stored configuration information, an SIB, or an RRC message) for only high priority transport blocks or only for a given CBR range.

In some aspects, the MAC layer may cluster transmit resources around a previously selected resource, such as a transmit resource for an early arrival transport block that triggered sensing and resource selection. Example <NUM> shows a square in a previously selected transmit resource for early arrival TB1. Sensing is requested of the PHY layer for TB2, and the PHY layer returns candidate resources (circles) that surround the previously selected resource (square). The MAC layer may select one of these candidate resources as a transmit resource for TB2. If TB3 arrives late, the MAC layer may select a transmit resource that is clustered around the transmit resources for TB <NUM> and TB2, such that transmit resources for TB <NUM>, TB2, and TB3 are clustered in some combination of FDM and/or back-to-back TDM.

In some aspects, multiple transport blocks may need to be separated in time and/or frequency. This may require an anti-cluster arrangement of transmit resources. Example <NUM> shows a reserved resource and how the MAC layer is not to select any transmit resource in slots <NUM>-<NUM> clustered around the reserved resource. For example, if one transport block is to be transmitted, the MAC layer may randomly select a transmit resource in slot <NUM> or slot <NUM>. Example <NUM> shows that the MAC layer has selected the transmit resource in slot <NUM>.

<FIG> is a diagram illustrating an example <NUM> of sensing and transmitting multiple transport blocks for NR sidelink, in accordance with the present disclosure.

Various aspects described herein involve multiple transport blocks rather than single transport blocks. Accordingly, a UE may perform multiple LBT procedures in parallel for respective transport blocks that are to use transmit resources in an FDM fashion. The UE may transmit those transport blocks for which an LBT procedure is successful. Example <NUM> shows that parallel LBT procedures are performed for TB <NUM> and TB2, which are to be transmitted in a same slot for FDM. However, only TB1 will be transmitted, as the LBT procedure for TB2 failed, and the LBT counter for TB2 has not completed by the time the slot in the resource selection window is to be transmitted. Transport blocks with different LBT priorities (channel access priority classes (CAPCs)) may have transmit resources in a same slot.

When identifying available resources as part of a "last-minute" reevaluation at a specified minimum time (T<NUM>) ahead of actual transmission of a transport block, the MAC layer may opportunistically use a subset of available resources for another transport block for which an LBT counter is completed. Example <NUM> shows that for a "last-minute" reevaluation by the PHY layer for a transmit resource at slot m' for TB1, there is a subset of resources (transmit resources <NUM>-<NUM>) that are available. Therefore, if TB2 arrives late, the MAC layer may select a transmit resource (e.g., resource <NUM>) at slot m (FDM with TB1) rather than later at slot m+<NUM>, which was an original random selection for TB2. Moving TB2 into an earlier transmit resource (if an LBT counter for TB2 is zero) may save what may have been another LBT procedure.

There are multiple uses for the subset of resources identified by the "last-minute" reevaluation, and some of these uses may involve reserved resources rather than resources for new initial transmissions. In some aspects, TB1 may have a reserved transmit resource on a PSSCH, such as for a retransmission, and TB2 may require a new transmit resource on the PSSCH. In some aspects, TB1 and TB2 may have reserved transmit resources on the PSSCH, but early transmission of TB2 may be allowed only if a time domain interval between reservations is smaller than a threshold time (as a penalty corresponding to an over the air reservation).

In some aspects, the UE may use additional collision protocols on top of LBT and autonomous sensing, so as to avoid collisions from early insertion ("jump-in") of a later transport block into a transmit resource. For example, a UE may generate a number t for each candidate transport block for early insertion up to a count of T, which has a value that is based at least in part on priorities of transport block candidates, a current CBR, an LBT type (sense initiator or resource sharer), and/or the like. A transport block that has a number t that is within the range of T may be inserted into a transmit resource of the subset of resources.

Example <NUM> shows that the subset of resources may include multiple slots, where a quantity of slots (or symbols) may be less than a channel occupancy time (COT) for sensing. There may be no reservation (or no equal or higher priority reservation) that prevents the UE from continuously transmitting over a specified quantity of symbols (if needed). In this case, TB2 does not need to be arranged for FDM with TB1. For instance, TB2 in example <NUM> may use available transmit resource number <NUM>, in <FIG>.

In some aspects, the UE may not be restricted by an LBT counter. For example, the UE may use the subset of resources for a new transport block arrival whose LBT counter has not yet completed (not reached zero). To counter this aggressive approach, the new transport block may be assigned to use a larger value T' than for a transport block with an LBT counter that has been completed, when using an advance collision avoidance protocol. This is particularly appropriate when the new transport block has no lower CAPC value than an original transport block.

As a result of the various procedures described above, the UE may more efficiently use transmit resources for multiple transport blocks. This may save the UE having to perform additional LBT procedures that consume time, power, processing resources, and signaling resources.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with the present disclosure. Example process <NUM> is an example where the UE (e.g., a UE <NUM> depicted in <FIG> and <FIG>, UE <NUM> depicted in <FIG>) performs operations associated with sensing and transmitting multiple transport blocks for NR sidelink.

As shown in <FIG>, in some aspects, process <NUM> may include determining candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks (block <NUM>). For example, the UE (e.g., using antenna <NUM>, demodulator <NUM>, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, modulator <NUM>, controller/processor <NUM>, and/or memory <NUM>) may determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include selecting, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks, such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel (block <NUM>). For example, the UE (e.g., using antenna <NUM>, demodulator <NUM>, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, modulator <NUM>, controller/processor <NUM>, and/or memory <NUM>) may select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the at least two transport blocks in the transmit resources (block <NUM>). For example, the UE (e.g., using antenna <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, modulator <NUM>, controller/processor <NUM>, and/or memory <NUM>) may transmit the at least two transport blocks in the transmit resources, as described above.

In a first aspect, determining the candidate resources includes a PHY layer of the UE determining the candidate resources based at least in part on a request from a MAC layer of the UE, where the PHY layer indicates the candidate resources to the MAC layer, and selecting the transmit resources includes the MAC layer selecting the transmit resources.

In a second aspect, alone or in combination with the first aspect, a quantity of the at least two transport blocks to be transmitted is limited based at least in part on a CBR, stored configuration information, an indication in a SIB, an indication in an RRC message, or some combination thereof.

In a third aspect, alone or in combination with one or more of the first and second aspects, a time to start transmitting the at least two transport blocks is based at least in part on a quantity of the at least two transport blocks to be transmitted.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting the transmit resources for the at least two transport blocks based at least in part on priorities of the at least two transport blocks.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, selecting the transmit resources for transmitting the at least two transport blocks includes randomly selecting the transmit resources such that the at least two transport blocks are transmitted in different subchannels of a same slot.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting one or more slots that each have a quantity of clear subchannels equal to or greater than a quantity of the at least two transport blocks.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, a quantity of subchannels to sense for the one or more slots is a greatest common divisor of a quantity of subchannels for the at least two transport blocks.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting transmit resources for the at least two transport blocks that have at least a specified amount of resource availability with respect to a resource selection window.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, selecting the one or more slots includes determining which slots have contiguous subchannels that are clear.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting the transmit resources from among contiguous candidate resources that are adjacent to a previously reserved transmit resource or a transmit resource used for a previous transport block.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting a transmit resource from among contiguous candidate resources that are not adjacent to a previously reserved transmit resource or a transmit resource used for a previous transport block.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, selecting the transmit resources for transmitting the at least two transport blocks includes selecting transmit resources for the at least two transport blocks independent of a quantity of retransmissions for each of the at least two transport blocks.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, process <NUM> includes sensing, for a second time, at least one resource of the transmit resources at a specified minimum time before transmitting a transport block in the at least one resource, where transmitting the at least two transport blocks includes transmitting the transport block in the at least one resource based at least in part on a determination that the at least one resource is still clear after sensing the at least one resource for the second time.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, process <NUM> includes performing a collision avoidance procedure for the at least one resource.

In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, process <NUM> includes selecting the transport block for transmission in the at least one resource based at least in part on a random number assigned to the transport block, and the random number being within a range of numbers for selection.

In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the at least one resource includes a plurality of slots.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, process <NUM> includes performing LBT procedures in parallel for the at least two transport blocks on at least two subchannels for a same slot, and transmitting the at least two transport blocks includes transmitting transport blocks of the at least two transport blocks whose LBT procedure is successful.

In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, process <NUM> includes performing LBT procedures in parallel for the at least two transport blocks on subchannels for different slots, and transmitting the at least two transport blocks includes transmitting transport blocks whose LBT procedure is successful.

In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, process <NUM> includes switching transmit resources for a pair of transport blocks of the at least two transport blocks based at least in part on completion of an LBT counter for one of the transport blocks of the pair of transport blocks and non-completion of an LBT counter for the other one of the pair of transport blocks.

In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, process <NUM> includes selecting, after sensing that a subset of the transmit resources are clear for a specified minimum time before transmitting the at least two transport blocks, a resource of the subset for transmitting another transport block with an LBT counter that is completed and that does not have a reserved transmit resource.

In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, process <NUM> includes selecting, after sensing that a subset of the transmit resources not reserved for the at least two transport blocks are clear for a specified minimum time before transmitting the at least two transport blocks, a resource of the subset for transmitting one of the at least two transport blocks that has an LBT counter that is completed, where the resource of the subset is in an earlier slot than an original reserved timing resource for the one of the at least two transport blocks.

In a twenty-second aspect, alone or in combination with one or more of the first through twenty-first aspects, process <NUM> includes selecting, after sensing that a subset of the transmit resources not reserved for the at least two transport blocks are clear for a specified minimum time before transmitting the at least two transport blocks, a resource of the subset for transmitting a transport block that has an LBT counter that is not completed.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication. The apparatus <NUM> may be a UE, or a UE may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM> and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses and/or one or more other components). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>. As further shown, the apparatus <NUM> may include one or more of a determination component <NUM> or a selection component <NUM>, among other examples.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as process <NUM> of <FIG>, or a combination thereof. In some aspects, the apparatus <NUM> and/or one or more components shown in <FIG> may include one or more components of the UE described above in connection with <FIG>. Additionally, or alternatively, one or more components shown in <FIG> may be implemented within one or more components described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

In some aspects, the transmission component <NUM> may be collocated with the reception component <NUM> in a transceiver.

The determination component <NUM> may determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks. In some aspects, the determination component <NUM> may include a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. The selection component <NUM> may select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel. In some aspects, the selection component <NUM> may a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. The transmission component <NUM> may transmit the at least two transport blocks in the transmit resources.

The determination component <NUM> may include a memory. The determination component <NUM> may include one or more processors coupled to the memory, one or more processors configured to determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks.

The selection component <NUM> may include a memory. The selection component <NUM> may include one or more processors coupled to the memory, the one or more processors configured to select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel.

The determination component <NUM> may include one or more instructions that, when executed by one or more processors of a UE, cause the UE to determine candidate resources on one or more PSSCHs that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to LBT completion instants for the at least two transport blocks.

The selection component <NUM> may include one or more instructions that, when executed by one or more processors of a UE, cause the UE to select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel.

The following provides an overview of some Aspects of the present disclosure:.

The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the aspects to the precise form disclosed.

A used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members.

Claim 1:
A user equipment, UE, (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>) for wireless communication, comprising:
a memory; and
one or more processors, coupled to the memory, configured to:
determine candidate resources on one or more physical sidelink shared channels, PSSCHs, that are clear for transmitting at least two transport blocks, based at least in part on sensing a plurality of subchannels on the one or more PSSCHs with respect to listen-before-talk, LBT, completion instants for the at least two transport blocks;
select, from among the candidate resources, transmit resources on the one or more PSSCHs for transmitting the at least two transport blocks, wherein the transmit resources have no gap between each other, such that the at least two transport blocks are transmitted in one of: different subchannels of a same slot, or contiguous slots of a same subchannel; and
transmit the at least two transport blocks in the transmit resources.