Quasi-colocation indication after downlink transmission

Quasi-colocation (QCL) indication is discussed after downlink transmission. In the management of multiple transmission-reception point (TRP) downlink transmissions, a second indication of a QCL assumption for a particular downlink transmission may be transmitted to receiving user equipment (UEs) after transmission of the downlink transmission. Once a TRP passes a listen before talk (LBT) procedure in a first time interval, it may send a first downlink control information (DCI) with indication of a first QCL assumption for the transmission in the first time interval. The TRP then transmits the downlink transmission intended for part of the multi-TRP downlink transmission. Upon receiving an indication that another of the TRPs was unsuccessful in its part of the multi-TRP transmission, the TRP may transmit a second DCI in a subsequent time interval with adjustments to the QCL assumption for the UEs to use in processing the downlink transmission from the first time interval.

BACKGROUND

Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to quasi-colocation (QCL) indication after downlink transmission.

Background

SUMMARY

In one aspect of the disclosure, a method of wireless communication includes receiving, by a user equipment (UE), a first downlink control information (DCI) including one or more transmission configuration indicator (TCI) states, wherein the one or more TCI states are associated with a scheduled multi-transmission-reception points (TRP) downlink transmission in a first time interval, monitoring, by the UE, for a second DCI in a subsequent time interval, wherein the second DCI includes an adjustment to the one or more TCI states of the first DCI, and in response to detection of the second DCI, processing, by the UE, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second quasi-colocation (QCL) assumption corresponding to the adjustment to the one or more TCI states.

In an additional aspect of the disclosure, a method of wireless communication includes transmitting, by a TRP in response to a successful listen before talk (LBT) procedure, a first DCI including one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs via shared communication spectrum, transmitting, by the TRP, a downlink transmission to one or more UEs in a first time interval in response to the successful LBT procedure on the shared communication spectrum, wherein the downlink transmission is intended for the multi-TRP downlink transmission, obtaining, by the TRP, an indication that at least one TRP of the one or more neighboring TRPs failed to successfully complete the multi-TRP downlink transmission during the first time interval, and transmitting, by the TRP, a second DCI in a subsequent time interval in response to the indication, wherein the second DCI includes an adjustment for the one or more TCI states reflecting a QCL assumption corresponding to the downlink transmission.

In an additional aspect of the disclosure, a method of wireless communication includes obtaining, by a TRP, coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs over a shared communication spectrum, encountering, by the TRP, an event that indicates an unsuccessful multi-TRP downlink transmission by the TRP, and signaling, by the TRP, the unsuccessful multi-TRP downlink transmission by the TRP to the one or more neighboring TRPs.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for receiving, by a UE, a first DCI including one or more TCI states, wherein the one or more TCI states are associated with a scheduled multi-TRP downlink transmission in a first time interval, means for monitoring, by the UE, for a second DCI in a subsequent time interval, wherein the second DCI includes an adjustment to the one or more TCI states of the first DCI, and means, executable in response to detection of the second DCI, for processing, by the UE, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second QCL assumption corresponding to the adjustment to the one or more TCI states.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for transmitting, by a TRP in response to a successful LBT procedure, a first DCI including one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs via shared communication spectrum, means for transmitting, by the TRP, a downlink transmission to one or more UEs in a first time interval in response to the successful LBT procedure on the shared communication spectrum, wherein the downlink transmission is intended for the multi-TRP downlink transmission, means for obtaining, by the TRP, an indication that at least one TRP of the one or more neighboring TRPs failed to successfully complete the multi-TRP downlink transmission during the first time interval, and means for transmitting, by the TRP, a second DCI in a subsequent time interval in response to the indication, wherein the second DCI includes an adjustment for the one or more TCI states reflecting a QCL assumption corresponding to the downlink transmission.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for obtaining, by a TRP, coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs over a shared communication spectrum, means for detecting, by the TRP, an event that indicates an unsuccessful multi-TRP downlink transmission by the TRP, and means for signaling, by the TRP, the unsuccessful multi-TRP downlink transmission by the TRP to the one or more neighboring TRPs.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to receive, by a UE, a first DCI including one or more TCI states, wherein the one or more TCI states are associated with a scheduled multi-TRP downlink transmission in a first time interval, code to monitor, by the UE, for a second DCI in a subsequent time interval, wherein the second DCI includes an adjustment to the one or more TCI states of the first DCI, and code, executable in response to detection of the second DCI, to process, by the UE, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second QCL assumption corresponding to the adjustment to the one or more TCI states.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to transmit, by a TRP in response to a successful LBT procedure, a first DCI including one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs via shared communication spectrum, code to transmit, by the TRP, a downlink transmission to one or more UEs in a first time interval in response to the successful LBT procedure on the shared communication spectrum, wherein the downlink transmission is intended for the multi-TRP downlink transmission, code to obtain, by the TRP, an indication that at least one TRP of the one or more neighboring TRPs failed to successfully complete the multi-TRP downlink transmission during the first time interval, and code to transmit, by the TRP, a second DCI in a subsequent time interval in response to the indication, wherein the second DCI includes an adjustment for the one or more TCI states reflecting a QCL assumption corresponding to the downlink transmission.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to obtain, by a TRP, coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs over a shared communication spectrum, code to detect, by the TRP, an event that indicates an unsuccessful multi-TRP downlink transmission by the TRP, and code to signal, by the TRP, the unsuccessful multi-TRP downlink transmission by the TRP to the one or more neighboring TRPs.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to receive, by a UE, a first DCI including one or more TCI states, wherein the one or more TCI states are associated with a scheduled multi-TRP downlink transmission in a first time interval, to monitor, by the UE, for a second DCI in a subsequent time interval, wherein the second DCI includes an adjustment to the one or more TCI states of the first DCI, and to process, by the UE, in response to detection of the second DCI, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second QCL assumption corresponding to the adjustment to the one or more TCI states.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to transmit, by a TRP in response to a successful LBT procedure, a first DCI including one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs via shared communication spectrum, to transmit, by the TRP, a downlink transmission to one or more UEs in a first time interval in response to the successful LBT procedure on the shared communication spectrum, wherein the downlink transmission is intended for the multi-TRP downlink transmission, to obtain, by the TRP, an indication that at least one TRP of the one or more neighboring TRPs failed to successfully complete the multi-TRP downlink transmission during the first time interval, and to transmit, by the TRP, a second DCI in a subsequent time interval in response to the indication, wherein the second DCI includes an adjustment for the one or more TCI states reflecting a QCL assumption corresponding to the downlink transmission.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to obtain, by a TRP, coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs over a shared communication spectrum, to detect, by the TRP, an event that indicates an unsuccessful multi-TRP downlink transmission by the TRP, and to signal, by the TRP, the unsuccessful multi-TRP downlink transmission by the TRP to the one or more neighboring TRPs.

DETAILED DESCRIPTION

FIG.1is a block diagram illustrating an example of a wireless communications system100that supports providing a quasi-colocation (QCL) assumption indication for a multiple transmission-reception point (TRP) downlink transmission after reception of the multiple TRP downlink transmission in accordance with aspects of the present disclosure. The wireless communications system100includes base stations105, UEs115, and a core network130. In some examples, the wireless communications system100may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or NR network. In some cases, wireless communications system100may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

UEs115may be dispersed throughout the wireless communications system100, and each UE115may be stationary or mobile. A UE115may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client. A UE115may also be a personal electronic device such as a cellular phone (UE115a), a personal digital assistant (PDA), a wearable device (UE115d), a tablet computer, a laptop computer (UE115g), or a personal computer. In some examples, a UE115may also refer to a wireless local loop (WLL) station, an Internet-of-things (IoT) device, an Internet-of-everything (IoE) device, an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles (UE115eand UE115f), meters (UE115band UE115c), or the like.

Wireless communications system100may include operations by different network operating entities (e.g., network operators), in which each network operator may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (e.g., time) may be partitioned and allocated to the different network operating entities for certain types of communication.

For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

In various implementations, wireless communications system100may use both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system100may employ license assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (NR-U), such as the 5 GHz ISM band. In some cases, UE115and base station105of the wireless communications system100may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs115or base stations105may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE115or base station105may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available.

A CCA may include an energy detection procedure to determine whether there are any other active transmissions on the shared channel. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include message detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

In general, four categories of LBT procedure have been suggested for sensing a shared channel for signals that may indicate the channel is already occupied. In a first category (CAT 1 LBT), no LBT or CCA is applied to detect occupancy of the shared channel. A second category (CAT 2 LBT), which may also be referred to as an abbreviated LBT, a single-shot LBT, or a 25-μs LBT, provides for the node to perform a CCA to detect energy above a predetermined threshold or detect a message or preamble occupying the shared channel. The CAT 2 LBT performs the CCA without using a random back-off operation, which results in its abbreviated length, relative to the next categories.

A third category (CAT 3 LBT) performs CCA to detect energy or messages on a shared channel, but also uses a random back-off and fixed contention window. Therefore, when the node initiates the CAT 3 LBT, it performs a first CCA to detect occupancy of the shared channel. If the shared channel is idle for the duration of the first CCA, the node may proceed to transmit. However, if the first CCA detects a signal occupying the shared channel, the node selects a random back-off based on the fixed contention window size and performs an extended CCA. If the shared channel is detected to be idle during the extended CCA and the random number has been decremented to 0, then the node may begin transmission on the shared channel. Otherwise, the node decrements the random number and performs another extended CCA. The node would continue performing extended CCA until the random number reaches 0. If the random number reaches 0 without any of the extended CCAs detecting channel occupancy, the node may then transmit on the shared channel. If at any of the extended CCA, the node detects channel occupancy, the node may re-select a new random back-off based on the fixed contention window size to begin the countdown again.

A fourth category (CAT 4 LBT), which may also be referred to as a full LBT procedure, performs the CCA with energy or message detection using a random back-off and variable contention window size. The sequence of CCA detection proceeds similarly to the process of the CAT 3 LBT, except that the contention window size is variable for the CAT 4 LBT procedure.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In wireless communications system100, base stations105and UEs115may be operated by the same or different network operating entities. In some examples, an individual base station105or UE115may be operated by more than one network operating entity. In other examples, each base station105and UE115may be operated by a single network operating entity. Requiring each base station105and UE115of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

In some cases, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

In some cases, wireless communications system100may utilize enhanced component carriers (eCCs). An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In certain instances, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum, such as NR-shared spectrum (NR-SS)). An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs115that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).

FIG.2shows a block diagram of a design of a base station105and a UE115, which may be one of the base station and one of the UEs inFIG.1. At base station105, a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor220may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor220may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor230may 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)232athrough232t. Each modulator232may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator232may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators232athrough232tmay be transmitted via the antennas234athrough234t, respectively.

At UE115, the antennas252athrough252rmay receive the downlink signals from the base station105and may provide received signals to the demodulators (DEMODs)254athrough254r, respectively. Each demodulator254may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator254may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector256may obtain received symbols from all the demodulators254athrough254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor258may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE115to a data sink260, and provide decoded control information to a controller/processor280.

On the uplink, at the UE115, a transmit processor264may receive and process data (e.g., for the PUSCH) from a data source262and control information (e.g., for the PUCCH) from the controller/processor280. The transmit processor264may also generate reference symbols for a reference signal. The symbols from the transmit processor264may be precoded by a TX MIMO processor266if applicable, further processed by the modulators254athrough254r(e.g., for SC-FDM, etc.), and transmitted to the base station105. At the base station105, the uplink signals from the UE115may be received by the antennas234, processed by the demodulators232, detected by a MIMO detector236if applicable, and further processed by a receive processor238to obtain decoded data and control information sent by the UE115. The processor238may provide the decoded data to a data sink239and the decoded control information to the controller/processor240.

The controllers/processors240and280may direct the operation at the base station105and the UE115, respectively. The controller/processor240and/or other processors and modules at the base station105may perform or direct the execution of various processes for the techniques described herein. The controllers/processor280and/or other processors and modules at the UE115may also perform or direct the execution of the functional blocks illustrated inFIGS.4A-4C, and/or other processes for the techniques described herein. The memories242and282may store data and program codes for the base station105and the UE115, respectively. A scheduler244may schedule UEs for data transmission on the downlink and/or uplink.

In general, two signals transmitted from the same antenna port may experience the same radio channel, while these same signals transmitted from two different antenna ports or transmission-reception points (TRPs) may experience different radio conditions. There can be scenarios in which signals transmitted from two different antenna ports or TRPs experience radio channels having common properties. In such cases the antenna ports/TRPs can be characterized as quasi-co-located (QCL). This QCL concept has been introduced to potentially help UEs with various operations, such as channel estimation, frequency offset error estimation, synchronization procedures, and the like. For example, if the UE knows that the radio channels corresponding to two different antenna ports/TRPs are QCL in terms of Doppler shift, then the UE could determine the Doppler shift associated with one antenna port/TRP and apply the result on both antenna ports/TRPs for channel estimation. Using the QCL concept, the UE avoids calculating the Doppler shift for both antenna ports/TRPs separately.

The different properties that may be common across antenna ports/TRPs may include Doppler spread/shift, average delay, delay spread, average gain, and spatial receiver parameters. These properties are referred to as the large-scale properties of the antennas port/TRP. The specific combinations of large-scale properties that may be shared across various antenna ports/TRPs have been grouped into four QCL types. QCL-Type A includes the common properties of Doppler shift, Doppler spread, average delay, and delay spread and has been applied for obtaining channel state information (CSI). QCL-Type B includes Doppler shift and Doppler spread and has also been applied for obtaining CSI. QCL-Type C includes average delay and delay spread and has been applied to obtain various measurement information, such as reference signal receive power (RSRP). QCL-Type D includes the spatial receiver parameter and has been applied to support beamforming.

A TCI state definition consists of a reference to channel state information-reference signal (CSI-RS) resources or a synchronization signal block (SSB) index. Up to 128 TCI states can be configured via radio resource control (RRC) signaling. Up to eight of those configured TCI states may then be activated through a medium access control-control element (MAC-CE) for a physical downlink shared channel (PDSCH). In 3GPP Releases 15/16 (Rels. 15/16), a QCL assumption for PDSCH transmission may be indicated in the scheduling DCI by indicating one or two TCI states from the activated TCI states.

In Rel. 15, the TCI field of the DCI may indicate one TCI state for the scheduled PDSCH, while in Rel. 16, the TCI field of the DCI may indicate one or two TCI states for the scheduled PDSCH. When two TCI states are indicated, it means a multi-TCI state PDSCH. For example, within a spatial division multiplex (SDM) scheme, the multi-TCI state PDSCH may indicate two sets of layers having different TCI states. Within a frequency division multiplex (FDM) scheme, the multi-state PDSCH may indicate two sets of resource blocks (RBs) have different TCI states. Within a time division multiplex (TDM) scheme, the multi-TCI state PDSCH may indicate different symbols or slots of the PDSCH or different repetitions in the time domain having different TCI states. Such schemes may further depend on the RRC configuration and other DCI fields.

FIG.3is a block diagram illustrating two TRP/antenna panels, TRP1and TRP2, engaged in multi-TRP downlink transmissions to UEs115a,115h, and115iover unlicensed, shared communication spectrum. Each of UEs115a,115h, and115imay receive a DCI with a TCI state(s) corresponding to a multi-TRP downlink transmission from both of TRP1and TRP2. UEs115a,115h, and115iwould use the QCL assumption with respect to that TCI state for receiving the downlink transmission. However, when either of TRP1or TRP2encounters transmission uncertainty, both TRPs may not transmit for a multi-TRP downlink transmission. For example, TRP1transmits DCI301and PDSCH302after detecting the LBT pass at300. However, TRP2fails to detect the LBT pass until303, and cannot participate in the joint transmission of PDSCH302. Therefore, the actual transmission of PDSCH302comes from TRP1and not from both of TRP1and TRP2.

When preparing DCI301, the network may not know in advance the actual TCI state(s) used. That information (LBT pass or not) is known a few microseconds before the joint transmission at a given TRP. Moreover, the LBT result at TRP2may not be known at TRP1until after some delay. In the described example ofFIG.3, when considering a single TCI state (Rel. 15), the QCL assumption for PDSCH302may be determined from a first TCI state where TRP1transmits PDSCH302by itself; from a second TCI state where TRP2transmits PDSCH302by itself; and a third TCI state where both TRP1and TRP2jointly transmit PDSCH302. The scheduling DCI, DCI301, indicates the third TCI state. However, because TRP2could not join the transmission, the actual TCI state would be the first TCI state. This example is relevant in the case of broadcast/multi-cast communications where multiple base stations/TRPs participate in a single frequency network (SFN) area, or a unicast PDSCH with an SFN transmission.

In another example of the aspect illustrated inFIG.3using a multi-TCI state (Rel. 16), the scheduling DCI, DCI301, may indicate first and second TCI states (e.g., under any of SDM, FDM, or TDM schemes). However, because TRP2could not join the joint transmission, PDSCH302has the first TCI state without the set of layers (SDM)/RBs (FDM)/symbols or slots (TDM) corresponding to the second TCI state. This example is relevant in single-DCI based multi-TRP downlink transmissions, where one DCI schedules a multi-TCI state PDSCH, as introduced in Rel. 16. The various aspects of the present disclosure are directed to providing a QCL assumption adjustment in a subsequent time interval after UEs receive the PDSCH in a previous time interval in order to accommodate the actual QCL assumption of the PDSCH in the previous time interval.

FIGS.4A-4Care block diagrams illustrating example blocks executed to implement aspects of the present disclosure. The example blocks ofFIG.4Awill also be described with respect to UE115as illustrated inFIGS.2and7.FIG.7is a block diagram illustrating UE115configured according to one aspect of the present disclosure. UE115includes the structure, hardware, and components as illustrated for UE115ofFIG.2. For example, UE115includes controller/processor280, which operates to execute logic or computer instructions stored in memory282, as well as controlling the components of UE115that provide the features and functionality of UE115. UE115, under control of controller/processor280, transmits and receives signals via wireless radios700a-rand antennas252a-r. Wireless radios700a-rincludes various components and hardware, as illustrated inFIG.2for UE115, including modulator/demodulators254a-r, MIMO detector256, receive processor258, transmit processor264, and TX MIMO processor266.

The example blocks ofFIGS.4B and4Cwill also be described with respect to base station105as illustrated inFIGS.2and8.FIG.8is a block diagram illustrating base station105configured according to one aspect of the present disclosure. Base station105includes the structure, hardware, and components as illustrated for base station105ofFIG.2. For example, base station105includes controller/processor240, which operates to execute logic or computer instructions stored in memory242, as well as controlling the components of base station105that provide the features and functionality of base station105. Base station105, under control of controller/processor240, transmits and receives signals via wireless radios800a-tand antennas234a-t. Wireless radios800a-tincludes various components and hardware, as illustrated inFIG.2for base station105, including modulator/demodulators232a-t, MIMO detector236, receive processor238, transmit processor220, and TX MIMO processor230.

According to the aspects described with respect toFIGS.4A-4C, with communications including multiple TRP transmissions, one of the TRPs of the set of TRPs making up the multiple TRP group may provide the scheduling of the coordinated transmissions for each of the TRPs of the group. This TRP that provides the scheduling and coordination may be referred to herein as the scheduling TRP. The other one or more TRPs of the multiple TRP group, which receive the scheduling and coordination instructions from the scheduling TRP for the coordinated transmissions, may be referred to herein as the non-scheduling TRP. These non-scheduling TRPs may operate, generally, as independent TRPs for other communications, but are a part of the multiple TRP group based on the control signaling for the scheduling and coordination from the scheduling TRP.

At block420(FIG.4C), a non-scheduling TRP may obtain coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs. The non-scheduling TRP may obtain such coordination signaling from the network or from the scheduling TRP. A non-scheduling TRP, which may be implemented by a base station, such as base station105, receives signaling via antennas234a-tand wireless radios800a-t. When base station105receives signaling coordinating a multiple TRP downlink transmission, base station105, under control of controller/processor240, executes multi-TRP transmission logic801, stored in memory242. Controller/processor240executes the instructions which result in the provision of the functionality of multi-TRP transmission logic801. Such execution of logic instructions to reveal the functionality is referred to herein as the “execution environment” of such logic.

At block410(FIG.4B), the scheduling TRP transmits a first DCI in response to a successful LBT procedure, wherein the first DCI includes one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs. The scheduling TRP has coordinated with the other TRPs for the multi-TRP downlink transmission to one or more served UEs. The first DCI includes either a single TCI state (Rel. 15) or one or more TCI states (up to two in Rel. 16) associated with the coordinated multi-TRP downlink transmission. In the case of single TCI state example, the indicated TCI state corresponds to a QCL assumption of a combined (SFNed) transmission from both TRP1and TRP2. In the case of the multiple TCI state example, the indicated TCI states in the first DCI may correspond to multiple of the TRP jointly transmitting the multi-TRP downlink transmission, where different indicated TCI states corresponds to QCL assumption for different set of layers (SDM scheme), or different set of RBs (FDM scheme), or different set of symbols or slots (TDM scheme). As the scheduling TRP detects success of the LBT procedure, it will then transmit the first DCI to the served UEs.

Further within the execution environment of multi-TRP transmission logic801, when the successful LBT procedure is detected, base station105uses the functionality of DCI generator804, stored in memory242, to generate the first DCI. The first DCI includes either a single TCI state (Rel. 15) or one or more TCI states (up to two in Rel. 16) associated with the coordinated multi-TRP downlink transmission. In generating the first DCI, the execution environment of DCI generator804references QCL assumption table803in memory242. QCL assumption table803provides reference to the TCI states or state identifiers (IDs) that correspond to particular QCL assumptions. The execution environments of both multi-TRP transmission logic801and DCI generator804will select the appropriate one or more TCI states for the first DCI. In the case of the multiple TCI state example, the available TCI states in the first DCI may correspond to multiple of the TRP jointly transmitting the multi-TRP downlink transmission and another option, such as the multi-TRP downlink transmission including transmissions from base station105, as the scheduling TRP. As base station105detects success of the LBT procedure, it will then transmit the first DCI to the served UEs via wireless radios800a-tand antennas234a-t.

At block400(FIG.4A), a UE receives the first DCI including the one or more TCI states associated with the scheduled multi-TRP downlink transmission in the first time interval. The UE, such as UE115, may receive the first DCI via antennas252a-rand wireless radios700a-reither independently transmitted by the scheduling TRP or jointly transmitted by two or more of the neighboring TRPs coordinated for the multi-TRP downlink transmission. In obtaining the first DCI which includes the scheduling of the downlink transmissions in the first time interval, UE115, under control of controller/processor280, executes QCL management logic701. The execution environment of QCL management logic701provide UE115with the functionality to interpret various TCI states with their corresponding QCL assumptions for processing the downlink transmissions. Upon receiving the first DCI, within the execution environment of QCL management logic701, UE115determines the one or more TCI states will be associated with the scheduled multi-TRP downlink transmission.

At block411(FIG.4B), the scheduling TRP transmits a downlink transmission to the one or more served UEs in the first time interval in response to the successful LBT procedure. As referenced above, the TRPs coordinated for the multi-TRP downlink transmission will each perform an LBT procedure for accessing the shared communication spectrum. According to the illustrated example, base station105, as the scheduling TRP, successfully passes the LBT procedure and transmits first DCI and data from data store805, in memory242, in a downlink transmission intended to be a part of the scheduled multi-TRP downlink transmission.

At block421(FIG.4C), the non-scheduling TRP encounters an event that indicates an unsuccessful multi-TRP downlink transmission. When implemented as a base station, such as base station105, base station105may encounter an event that either prohibits base station105from transmitting the multi-TRP downlink transmission or prevents the UE from successfully receiving the transmission. The event encountered may include a failed LBT procedure or delay of LBT success until after the period scheduled for the multi-TRP downlink transmission. Thus, in performing an LBT procedure within the execution environment of LBT logic802, base station105may detect failure of the LBT. Additionally, base station105, as the non-scheduling TRP, may receive interim priority scheduling to transmit data with a higher priority than the data for the multi-TRP downlink transmission. With the higher priority data, base station105, as the non-scheduling TRP, would change its transmission schedule to transmit the new, higher priority data. Similarly, base station105may transmit the data intended for the multi-TRP downlink transmission, but the transmission is blocked either by excessive interference, geographic feature, a large metallic object in motion (e.g., automobile, airplane, train, elevator, etc.), or the like. In each such case, the multi-TRP downlink transmission is not successfully completed.

At block422(FIG.4C), the non-scheduling TRP signals the unsuccessful multi-TRP downlink transmission to the neighboring TRPs, including, at least, the scheduling TRP. The neighboring TRPs that have coordinated for the multi-TRP downlink transmission, including base station105, as a non-scheduling TRP, may be connected via backhaul134with each other. As base station105, the non-scheduling TRP, discovers the event that indicates the unsuccessful multi-TRP downlink transmission, it will signal, under control of controller/processor240, the transmission failure at least to the scheduling TRP via backhaul interface806and backhaul134.

At block412(FIG.4B), the scheduling TRP obtains an indication that at least one of the neighboring TRPs filed to successfully complete the multi-TRP downlink transmission during the first time interval. As indicated above, the non-scheduling TRP signals the detected failure of transmission at least to the scheduling TRP, here the scheduling TRP is implemented by base station105. Base station105, the scheduling TRP, thus, receives this indication, via backhaul134and backhaul interface806, which informs that the scheduled multi-TRP downlink transmission did not occur as scheduled.

At block413(FIG.4B), the scheduling TRP transmits a second DCI in a subsequent time interval in response to obtaining the indication, wherein the second DCI includes an adjustment to the TCI states of the first DCI that reflect the actual QCL assumption corresponding to the downlink transmission as made by the scheduling TRP. Within the execution environment of multi-TRP transmission logic801, when base station105, as the scheduling TRP, finds out that the scheduled multi-TRP downlink transmission did not occur as scheduled, for which the TCI states in the first DCI were specifically selected, it access DCI generator804again to generate the second DCI in the subsequent time interval. The execution environments of multi-TRP transmission logic801and DCI generator804determine the appropriate QCL assumption of the previously-transmitted downlink transmission by accessing QCL assumption table803, in memory242. Base station105, which the execution environments of multi-TRP transmission logic801and DCI generator804determines adjustments to the TCI states, such that the adjustments to the TCI states reflect how the downlink transmission actually occurred. These adjustments are included in the second DCI generated by DCI generator804and transmitted to the UEs via wireless radios800a-tand antennas234a-t.

It should be noted that, in alternative aspects of the present disclosure, the second DCI may be transmitted from the non-scheduling TRP directly in the subsequent time interval (such as, in response to the non-scheduling TRP not being able to participate in the joint transmission in the first time interval due to LBT failure while LBT passes in the subsequent time interval) or may be transmitted jointly by all of the coordinated neighboring TRPs.

At block401(FIG.4A), a determination is made by the UE whether it has detected a second DCI in a subsequent time interval. UE115will have buffered the samples of the scheduled multi-TRP downlink transmissions received during the first time interval and may store the buffered samples in data buffer703. Before processing the buffered samples, UE115monitors for a second DCI. If no second DCI has been received, then, at block402(FIG.4A), UE115processes the scheduled multi-TRP downlink transmission in the subsequent time interval according to a first QCL assumption corresponding to the TCI state(s) included in the first DCI. Thus, if either no second DCI is received or interference or poor channel quality prevented UE115from successfully receiving the second DCI, UE115, within the execution environment of QCL management logic701, will process the buffered samples of the scheduled multi-TRP downlink transmissions in data buffer703according to a first QCL assumption that corresponds to the original TCI states included in the first DCI, where UE115determines the first QCL assumption via the QCL assumption table702, in memory282. UE115uses the original TCI states in the first DCI as an index in QCL assumption table703to find the first QCL assumption to apply.

Otherwise, if UE115detects a second DCI, then, at block403(FIG.4A), UE115processes the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second QCL assumption corresponding to the adjustments received in the second DCI that adjust the TCI states received in the first DCI. As the scheduling TRP knows that the multi-TRP downlink transmission did not occur as scheduled, it sends the adjustments to the TCI states in the second DCI in the subsequent time interval in order to inform UE115of the second or adjusted QCL assumption to apply to the downlink transmission that corresponds to the adjustments made to the original TCI states. UE115uses the adjustments with QCL assumption table702to find the adjusted QCL assumption to use in processing the buffered sample of the multi-TRP downlink transmission in data buffer703.

FIG.5is a block diagram illustrating two TRPs or antenna panels, TRP1and TRP2, conducting multi-TRP downlink transmissions according to one aspect of the present disclosure with multiple UEs, UEs115a,115h, and115i. The scheduling TRP, TRP1, coordinates with the non-scheduling TRP, TRP2, to conduct a multi-TRP downlink transmission to the served UEs, UEs115a,115h, and115i. TRP1and TRP2schedule to jointly transmit PDSCH503within a first time interval500. TRP1identifies the one or more TCI states to include in the scheduling DCI, DCI502, that corresponds to the QCL assumption associated with the joint transmission of PDSCH503by TRP1and TRP2. Alternatively, when more than one TCI state is included, TRP1may provide an additional possible TCI state that corresponds to another QCL assumption, such as for PDSCH503being transmitted solely by TRP.

At501, TRP1detects a successful LBT procedure that secures access to the shared communication spectrum for first time interval500. In response to detecting the successful LBT procedure at501, TRP1transmits the scheduling DCI, DCI502. DCI502includes one or more TCI states that correspond to the QCL assumption at least for the joint transmission of PDSCH503by TRP1and TRP2. TRP1also transmits PDSCH503with the intent that it will be part of the multi-TRP downlink transmission with TRP2. However, at501, TRP2has not passed its LBT procedure and, thus, cannot begin its transmission. In fact, TRP2does not detect an LBT pass until505, within the next time interval504.

It should be noted that, as referenced above, the transmission interruption experienced by TRP2can also be attributed to other interrupting events. For example, TRP2could have experienced a change of scheduling information after the scheduling DCI, DCI502, has already been transmitted. A change of scheduling may direct TRP2to send urgent traffic to one of UEs115a,115h, or115i, or even another UE and, therefore, cannot participate in the joint transmission. In another example, TRP2could experience signal blocking. Even though TRP2participated in the joint transmission or PDSCH503, due to transmission blocking (interference, channel quality, blocking geographic feature) its transmission is not received, or is received weakly, by one or more of UEs115a,115h, or115i. TRP2may discover this transmission blocking information through feedback from UEs115a,115h, or115iafter transmission of both DCI502and PDSCH503.

Upon detecting that it has not passed the LBT procedure at501, TRP2signals TRP1that it encountered an event that resulted in an unsuccessful transmission of PDSCH503by TRP2. Accordingly, PDSCH503has been transmitted solely by TRP1. Upon receipt of this signaling from TRP2, TRP1determines to transmit a second DCI, DCI2506during next time interval504. DCI2506includes adjustments to the TCI states that were included in the scheduling DCI, DCI502. The adjustments change the TCI states to correspond to a QCL assumption that reflects the transmission of PDSCH503solely by TRP1. For example, the adjustments within DCI2506may provide another TCI state ID or set of TCI state IDs associated with the transmitted PDSCH503. Alternatively, the adjustments within DCI2506may provide an indication of which of the TCI states identified in the first DCI, DCI502, either are to be used or that should not be used. For example, if DCI502includes two TCI states in which one TCI state corresponded to a first QCL assumption for PDSCH503being jointly transmitted by TRP1and TRP2and the other TCI state corresponded to a second QCL assumption for PDSCH503being transmitted solely by TRP1, then the adjustment included in DCI2506may indicate to UEs115a,115h, and115ieither to use the second QCL assumption or that the first QCL assumption is not used.

In a further alternative, DCI2506may include a bitmap indicating whether each TRP in the set of TRPs transmitted or not. Based on the TRPs indicated to have transmitted, UEs115a,115h, and115imay derive the QCL assumption or the TCI state based on a predetermined mapping from the TCI state identified in DCI502.

UEs115a,115h, and115imay buffer the samples of the scheduled multi-TRP downlink transmission of PDSCH503for the duration of first time interval500and not begin processing until it determines whether or not a second DCI, DCI2506has been received. If received, UEs115a,115h, and115iwill receive the scheduled multi-TRP downlink transmission of PDSCH503using the QCL assumption corresponding to the TCI states identified in DCI502. Otherwise, if the second DCI, DCI2506has not been received (either because it was not sent or because UEs115a,115h, or115icould not successfully receive DCI2506), UEs115a,115h, and115iwould process the samples of the multi-TRP downlink transmission of PDCSH503using the second QCL assumption corresponding to the adjusted TCI states identified in the second DCI, DCI2506.

As such, according to the various aspect of the present disclosure, a QCL assumption indication can be provided after reception of the downlink transmission. Another DCI can be transmitted by the TRP, whether solely by TRP1or solely by TRP2, or jointly by TRP1and TRP2, and received by UEs115a,115h, and115iduring next time interval504to indicate the actual QCL assumption of one or more downlink transmissions received in first time interval500.

It should be noted that the time intervals, whether a first time interval, a next time interval, or a subsequent time interval, may include a slot, channel occupancy time (COT), related to the successful LBT procedure, or the like. The TRP transmitting the second DCI, DCI2506can identify the periodicity of the search space set during which UEs115a,115h, and115imay monitor for the second DCI. The TRP transmitting the second DCI, DCI2506can then transmit DCI2506during that search space set.

It should further be noted that the second DCI, DCI2506can be configured as a group common DCI with a specific radio network temporary identifier (RNTI) targeted toward a group of UEs, or can be a UE-specific DCI.

FIG.6Ais a block diagram illustrating a detail of DCI2506configured according to one aspect of the present disclosure as depicted inFIG.5. The second DCI, DCI2506may include more than just a single adjustment to the one or more TCI states provided in the first DCI. For example, DCI2506may be configured to have multiple TCI fields600. Thus, the second DCI, DCI2506, may include more adjusted TCI state information than in the first DCI in order to accommodate adjustments for multiple different downlink transmissions that may have been sent during the first time interval to one or more UEs. The second DCI, DCI2506, provides adjustments for all downlink transmissions during the first time interval, which may have been scheduled by separately individual first DCIs. When second DCI, DCI2506, is group-common, the multiple downlink transmissions in the first time interval, for which the second DCI, DCI2506, provides QCL assumption adjustments, can correspond to multiple UEs. As illustrated inFIG.6A, DCI2506includes N TCI fields, TF_1-TF_N. Each of TF_1-TF_N can provide an adjustment of TCI states or TCI state IDs for multiple downlink transmissions from the first time interval. Such second DCI, DCI2506, may be received in different component carriers (CCs) or multiple LBT bandwidths, depending on the scheme operating (e.g., SDM, FDM, TDM, etc.). Thus, a different set of TCI states may be included within TCI fields600to accommodate the QCL relationships of TRPs that have transmitted different downlink transmissions over first time interval500.

FIG.6Bis a block diagram illustrating a detail of TF_2, as configured according to one aspect of the present disclosure, within TCI fields600of DCI2506. In addition to DCI2506including TCI fields600with multiple fields with independent TCI state adjustments for different CCs, LBT bandwidths, and the like, each TCI field, such as TF_2, may include multiple TCI sub-fields, such as TCI sub-fields602. TCI sub-fields include sub-fields, TSbF_1-TSbF_K. Such further division of TCI adjustment information may provide for a more granular adjustment, such as different TCI adjustments for the different downlink transmissions that occurred during first time interval500.

As noted above, each TCI field, TF_1-TF_N (FIG.6A), or TCI sub-field, TSbF_1-TSbF_K may include adjustments in various forms. In a first example form, an adjustment for TCI fields600or TCI sub-fields601, may include a new TCI state ID or multiple TCI state IDs for the received, scheduled multi-TRP downlink transmission (e.g., PDSCH503(FIG.5)). A second example form of adjustment may include an indication of which TCI state identified in the first DCI either is not used or is, in fact, used. Thus, when the first DCI includes multiple TCI states, the adjustment of the second example form would instruct the associated UEs (e.g., UEs115a,115h, and115i) which of the identified TCI states from the first DCI to use or to not use in processing the received samples of the scheduled multi-TRP downlink transmissions.

A third example form of adjustment may include a bitmap indicating whether each TRP in a set of TRPs either did or did not transmit. Based on the identified TRPs that joined the multi-TRP downlink transmission, a served UE (e.g., UEs115a,115h, and115i) can derive the QCL assumption or TCI state based on a preconfigured mapping from the TCI states identified in the first DCI.

The functional blocks and modules inFIGS.4A-4Cmay comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

The various aspects of the present disclosure may be implemented in many different ways, including methods, processes, non-transitory computer-readable medium having program code recorded thereon, apparatus having one or more processors with configurations and instructions for performing the described features and functionality, and the like. For example, a first aspect of wireless communication, includes receiving, by a UE, a first DCI including one or more TCI states, wherein the one or more TCI states are associated with a scheduled multi-TRP downlink transmission in a first time interval, monitoring, by the UE, for a second DCI in a subsequent time interval, wherein the second DCI includes an adjustment to the one or more TCI states of the first DCI, and in response to detection of the second DCI, processing, by the UE, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a second QCL assumption corresponding to the adjustment to the one or more TCI states.

A second aspect, based on the first aspect, further including storing, by the UE, buffered samples of the scheduled multi-TRP downlink transmission received from one or more TRPs in the first time interval.

A third aspect, based on the first aspect, further including, in response to a failure to detect the second DCI, processing, by the UE, the scheduled multi-TRP downlink transmission in the subsequent time interval according to a first QCL assumption corresponding to the one or more TCI states of the first DCI.

A fourth aspect, based on the first aspect, wherein the first and second time intervals include one of: a slot; or a channel occupancy time (COT) associated with success of a channel sensing procedure.

A fifth aspect, based on the first aspect, wherein the second DCI is received according to one of: a group common DCI configuration for a group of UEs including the UE; or a UE-specific DCI configured for the UE.

A sixth aspect, based on the first aspect, wherein the second DCI includes a plurality of TCI fields with, wherein each TCI field of the plurality of TCI fields corresponds to one of: a component carrier or a LBT bandwidth, and identifies the adjustment associated with the one of: the component carrier or the LBT bandwidth.

A seventh aspect, based on the sixth aspect, wherein each TCI field includes a plurality of sub-fields identifying the adjustment associated with one of: a set of symbols or a slot within the first time interval.

An eighth aspect, based on the seventh aspect, wherein the adjustment within the second DCI includes one of: one or more updated TCI states identifying the second QCL assumption; an identification of one or more unused TCI states of the one or more TCI states of the first DCI not used for the second QCL assumption of the candidate downlink transmission; or a bitmap indicating a transmission success state for each TRP of the one or more TRPs with regard to the multi-TRP transmission, wherein the UE determines the second QCL assumption based on the one or more transmitting TRPs of the one or more TRPs that transmitted the candidate downlink transmissions.

A ninth aspect, based on the first aspect, wherein the first and second DCIs are received by the UE one of: independently from one TRP, or jointly from two or more TRP.

A tenth aspect, based on the first aspect, further including determining, by the UE, an unsuccessful receipt of a subset of candidate downlink transmissions of the candidate downlink transmissions from one or more blocked TRPs of the one or more TRPs, wherein the unsuccessful receipt includes one of: a failure to receive the subset of candidate downlink transmissions, or an incapability of the TRP to successfully receive the subset of candidate downlink transmissions based on a signal quality of the subset of candidate downlink transmissions; and transmitting, by the UE, feedback to the one or more blocked TRPs, wherein the feedback indicates the unsuccessful receipt of the subset of candidate downlink transmissions.

An eleventh aspect including any combination of the first through the tenth aspects.

A twelfth aspect of wireless communication includes transmitting, by a TRP in response to a successful LBT procedure, a first DCI including one or more TCI states for a multi-TRP downlink transmission coordinated with one or more neighboring TRPs via shared communication spectrum; transmitting, by the TRP, a downlink transmission to one or more UEs in a first time interval in response to the successful LBT procedure on the shared communication spectrum, wherein the downlink transmission is intended for the multi-TRP downlink transmission; obtaining, by the TRP, an indication that at least one TRP of the one or more neighboring TRPs failed to successfully complete the multi-TRP downlink transmission during the first time interval; and transmitting, by the TRP, a second DCI in a subsequent time interval in response to the indication, wherein the second DCI includes an adjustment for the one or more TCI states reflecting a QCL assumption corresponding to the downlink transmission.

A thirteenth aspect, based on the twelfth aspect, wherein the first and second time intervals include one of: a slot; or a COT associated with success of a channel sensing procedure, including the successful LBT procedure.

A fourteenth aspect, based on the twelfth aspect, further including identifying, by the TRP, for a periodicity of search space configured for the one or more UEs; and determining, by the TRP, the second time interval within a search space after the first time interval in accordance with the periodicity.

A fifteenth aspect, based on the twelfth aspect, wherein the second DCI is configured according to one of: a group common DCI configured for a group of UEs including the one or more UEs; or a UE-specific DCI configured for an identified UE of the one or more UEs.

A sixteenth aspect, based on the twelfth aspect, wherein the second DCI includes a plurality of TCI fields with, wherein each TCI field of the plurality of TCI fields corresponds to one of: a component carrier or a LBT bandwidth, and identifies the adjustment associated with the one of: the component carrier or the LBT bandwidth.

A seventeenth aspect, based on the sixteenth aspect, wherein each TCI field includes a plurality of sub-fields identifying the adjustment associated with one of: a set of symbols or a slot within the first time interval.

An eighteenth aspect, based on the seventeenth aspect, wherein the adjustment within the second DCI includes one of: one or more updated TCI states identifying the QCL assumption; an identification of one or more unused TCI states of the one or more TCI states of the first DCI not used for the QCL assumption of the downlink transmission; or a bitmap indicating a transmission success state for each TRP of the TRP and the one or more neighboring TRPs with regard to the multi-TRP downlink transmission.

A nineteenth aspect, based on the twelfth aspect, wherein the indication identifies the failure of the at least one TRP to successfully complete the multi-TRP downlink transmission is associated with one of: failure to pass an LBT procedure by the multi-TRP downlink transmission coordinated with the one or more neighboring TRPs; a change of transmission scheduling received by the at least one TRP; or a blocked transmission of the at least one TRP.

A twentieth aspect including any combination of the twelfth through the nineteenth aspects.

A twenty-first aspect of wireless communication includes obtaining, by a TRP, coordination signaling for a multi-TRP downlink transmission during a first time interval with one or more neighboring TRPs over a shared communication spectrum, encountering, by the TRP, an event that indicates an unsuccessful multi-TRP downlink transmission by the TRP; and signaling, by the TRP, the unsuccessful multi-TRP downlink transmission by the TRP to the one or more neighboring TRPs.

A twenty-second aspect, based on the twenty-first aspect, wherein the event indicating the unsuccessful multi-TRP downlink transmission includes one of: a failure of the TRP to pass a listen before talk (LBT) procedure on the shared communication spectrum; receipt of a change of transmission scheduling for the first time interval; or detection of a blocked downlink transmission, wherein the blocked downlink transmission was intended for the multi-TRP downlink transmission.

A twenty-third aspect, based on the twenty-second aspect, further including transmitting, by the TRP, a downlink transmission to one or more UEs on the shared communication spectrum intended for the multi-TRP downlink transmission; receiving, by the TRP, feedback from the one or more UEs indicating unsuccessful receipt of the downlink transmission; and determining, by the TRP, that the event is the blocked downlink transmission based on the feedback from the one or more UEs.

A twenty-fourth aspect, based on the twenty-first aspect, further including transmitting, by TRP, a first DCI including one or more TCI states for the multi-TRP downlink transmission coordinated with one or more neighboring TRPs, wherein the transmitting is performed one of: independently by the TRP, or jointly by the TRP and at least one TRP of the one or more neighboring TRPs.

A twenty-fifth aspect, based on the twenty-first aspect, further including transmitting, by the TRP, a second DCI in a subsequent time interval on the shared communication spectrum in response to the event, wherein the second DCI includes an adjustment for one or more TCI states transmitted in a first DCI during the first time interval, wherein the adjustment reflects a QCL assumption corresponding to one or more downlink transmissions of the multi-TRP downlink transmission transmitted by at least one transmitting TRP of the one or more neighboring TRPs, wherein the transmitting is performed one of: independently by the TRP, or jointly by the TRP and at least one TRP of the one or more neighboring TRPs.

A twenty-sixth aspect, based on the twenty-first aspect, wherein the first time intervals includes one of: a slot; or a COT associated with success of a channel sensing procedure.

A twenty-seventh aspect including any combination of the twenty-first through the twenty-sixth aspects.