Feedback for multicast transmissions while in an inactive or idle mode

Methods, systems, and devices for multicast wireless communications are described. A base station may configure a user equipment (UE) for providing feedback for multicast transmissions from the base station while the UE is in an inactive or idle mode. Based on a configuration sent to the UE from the base station, the UE may determine resources or a timing advance (TA) to use for transmission of a feedback message for multicast communications. A base station may configure a UE with multiple TA commands, each corresponding to a TA value and a set of channel metrics associated with group of cells including a serving cell of the UE. Based on measure channel metrics at the UE, the UE may determine a TA to use for multicast feedback. TA values may be determined using neural network modeling.

TECHNICAL FIELD

The following relates generally to wireless communications, and more specifically, to feedback for multicast transmissions.

DESCRIPTION OF THE RELATED TECHNOLOGY

In some wireless communications systems, after receiving a message from a base station, a UE may transmit feedback to the base station indicating whether the message was successfully received. For example, a base station may transmit a multicast message to one or more UEs, such as a group of UEs, served by the base station, and a UE in the group may transmit feedback for the multicast message in accordance with a timing advance (TA) associated with each of the UEs. UEs in an inactive or idle mode, however, may not have valid TAs, and may therefore refrain from transmitting feedback or may transition to a connected mode to obtain a valid TA before transmitting feedback. Refraining from transmitting feedback or transitioning to a connected mode may result in increased latency, wasted UE resources (such as power or battery life, among other examples), or inefficient use of network resources, among other issues.

SUMMARY

One innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communications at a user equipment (UE). The method includes receiving, from a base station, one or more configurations for the UE to use, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station, monitoring, by the UE while in the inactive mode or the idle mode, a set of time frequency resources configured for multicast transmissions from the base station, and transmitting, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a wireless communication device. The wireless communication device includes a processor, memory coupled with the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to: receive, from a base station, one or more configurations for the UE to use, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station, monitor, by the UE while in the inactive mode or the idle mode, a set of time frequency resources configured for multicast transmissions from the base station, and transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring.

In some implementations, the methods and wireless communication devices may be configured to determine a set of random access channel resources available for multicast feedback based at least in part on a resource allocation indicated by the one or more configurations, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages via the set of random access channel resources.

In some implementations, the methods and wireless communication devices may be configured to determine a set of random access channel preambles available for multicast feedback based at least in part on a resource allocation indicated by the one or more configurations, and select a preamble of the set of random access channel preambles, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using the selected preamble.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communications at a base station. The method includes transmitting, to a UE, one or more configurations for multicast feedback for use by the UE while in an inactive mode or an idle mode, transmitting one or more multicast transmissions via a set of time frequency resources configured for multicast communications; and monitoring, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a wireless communication device. The wireless communication device includes a processor, memory coupled with the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to: transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode, transmit one or more multicast transmissions via a set of time frequency resources configured for multicast communications, and monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations.

In some implementations, the methods and wireless communication devices may be configured to transmit an indication of a set of random access channel resources available for multicast feedback in the one or more configurations, and monitor the set of random access channel resources for the one or more multicast feedback messages.

In some implementations, the methods and wireless communication devices may be configured to transmit an indication of a set of random access channel preambles available for multicast feedback in the one or more configurations, and monitor for the one or more multicast feedback messages based on the set of random access channel preambles.

DETAILED DESCRIPTION

In some wireless communications systems, a device such as a user equipment (UE) or a base station may support feedback messaging, such as hybrid automatic repeat request (HARQ) feedback messaging for multicast communications. A base station may configure resources for multicast feedback, and a UE may transmit a feedback message (such as an acknowledgement (ACK) feedback message or a negative ACK (NACK) feedback message) to the base station using the configured resources. For example, a base station may transmit a multicast message to a group of UEs. A UE in the group may fail to receive the multicast message and, based on the failure, the UE may transmit a NACK feedback message to the base station for a retransmission of the multicast message. To reduce channel overhead, the resources available for multicast feedback may be shared among multiple UEs, such as all the UEs in the group, and the resources may be referred to as shared resources. Each of the multiple UEs in the group may use the resources (for example, shared physical uplink control channel (PUCCH) resources) to transmit a respective feedback message for the multicast message to the base station.

A base station may configure a timing advance (TA) for a UE in an active mode, such as in a radio resource control (RRC) connected mode, and the UE may transmit feedback for multicast messages using the TA. For example, the base station may configure the TA for the UE after the UE enters the active mode and establishes a connection with the base station, and the UE may use the TA to transmit, to the base station, a feedback message in response to a multicast message from the base station. In some aspects, the base station may transmit the multicast message to a group of UEs including the UE. The UEs in the group that are in an inactive mode (such as an RRC inactive mode) or an idle mode (such as an RRC idle mode) may monitor for the multicast message, but because the UEs are in the inactive mode or the idle mode, the UEs may not have a valid or accurate TA to use for transmitting the feedback message in response to the multicast message. To transmit a feedback message, each UE in the inactive mode or the idle mode may enter a connected mode to establish a connection with the base station and obtain a TA, which may increase overhead or use power resources at the UE and increase the latency associated with transmission of the feedback message and reception of any subsequent transmissions such as a retransmission of the multicast message in the case of NACK feedback. Further, some UEs in inactive or idle mode may refrain from transmitting the feedback message for the multicast message. In such examples, even if multiple UEs in the inactive mode or the idle mode fail to successfully decode the multicast message, the base station may not perform retransmission of the multicast message because the base station may not receive any feedback messages from the multiple UEs.

Various aspects generally relate to feedback, and more specifically, to techniques for UEs in an inactive mode or an idle mode to transmit feedback for multicast messages. Such techniques may include a base station transmitting a configuration to a UE to configure the UE for transmitting feedback for multicast messages while the UE is in the inactive mode or the idle mode. The configuration may indicate resources (such as random access channel (RACH) resources or PUCCH resources) or RACH preambles, among other information, for the UE. The base station may transmit a multicast message to the UE in the inactive mode or the idle mode, and the UE may use the indicated resources to transmit feedback for the multicast message. For example, a UE operating in the inactive mode or the idle mode may determine a RACH preamble from multiple RACH preambles or a set of resources from the RACH resources, the PUCCH resources, or a resource pool available for feedback, and may use the determined resources to transmit feedback using the determined RACH preamble.

Additionally, or alternatively, a base station may transmit a TA command to a UE or a group of UEs. The TA command may indicate a TA for the UE or a group of UEs to use, and the TA may be based on channel metrics, channel conditions, or other factors associated with the UE or the group of UEs. In some implementations, the base station may transmit multiple TA commands, and each TA command may indicate a TA that corresponds to a respective set of channel metrics for a serving cell of the UE or the group of UEs or for one or more neighboring cells. The base station may determine TA values using various techniques, such as neural network modeling (which may include the use of historical or current data), environmental conditions, or information from neighboring cell(s), among other information.

The base station may transmit multiple multicast control channels, which may be associated with various multicast services, to the UE, and the UE may successfully decode a quantity of the multicast control channels over a given duration (such as over a set of time occasions allocated for multicast communications). The UE may transmit a reception status report indicating the quantity of successfully decoded multicast control channels. In such implementations, to determine the number of UEs that have successfully or unsuccessfully decoded the multicast control channels, a base station may determine the UEs (including active, idle, and inactive UEs) that are monitoring for a given multicast service over a duration, which may be referred to herein as a counting duration. To limit the number of UEs transmitting reception status reports during the counting duration, a base station may configure some or all UEs that the base station serves with a probability indicator that corresponds to a probability of the UE transmitting feedback for the multicast message during the counting duration.

Particular implementations of the subject matter described in this disclosure may be implemented to realize one or more of the following potential advantages. In some implementations, a base station may use the described techniques to configure UEs in an inactive or idle mode for the transmission of feedback messages for multicast messages. Such techniques may enable the base station use feedback from inactive UEs or idle UEs to determine whether to retransmit multicast messages. Such techniques may also enable inactive UEs or idle UEs to transmit feedback messages for multicast messages without a configured TA or without having to enter a connected mode, which may reduce overhead and latency, improve UE performance, and increase battery life, among other advantages.

Various aspects generally relate to wireless communications systems, and more specifically to feedback for multicast transmissions. Aspects of the disclosure are described with respect to process flows. Aspects of the disclosure are also illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to feedback for multicast transmissions.

The base stations105may communicate with the core network130, or with one another, or both. For example, the base stations105may interface with the core network130through one or more backhaul links120(for example, via an S1, N2, N3, or other interface). The base stations105may communicate with one another over the backhaul links120(for example, via an X2, Xn, or other interface) either directly (for example, directly between base stations105), or indirectly (for example, via core network130), or both. In some examples, the backhaul links120may be or include one or more wireless links.

The communication links125shown in the wireless communications system100may include uplink transmissions from a UE115to a base station105, or downlink transmissions from a base station105to a UE115. Carriers may carry downlink or uplink communications (for example, in an FDD mode) or may be configured to carry downlink and uplink communications (for example, in a TDD mode).

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (for example, in the time domain) of the wireless communications system100and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (for example, the quantity of symbol periods in a TTI) may be variable. Additionally, or alternatively, the smallest scheduling unit of the wireless communications system100may be dynamically selected (for example, in bursts of shortened TTIs (sTTIs)).

Each base station105may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a base station105(for example, over a carrier) and may be associated with an identifier for distinguishing neighboring cells (for example, a physical cell identifier (PCID), a virtual cell identifier (VCID), or others). In some examples, a cell may also refer to a geographic coverage area110or a portion of a geographic coverage area110(for example, a sector) over which the logical communication entity operates. Such cells may range from smaller areas (for example, a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station105. For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with geographic coverage areas110, among other examples.

In some examples, transmissions by a device (for example, by a base station105or a UE115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (for example, from a base station105to a UE115). The UE115may report feedback that indicates precoding weights for one or more beam directions, and the feedback may correspond to a configured quantity of beams across a system bandwidth or one or more sub-bands. The base station105may transmit a reference signal (for example, a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS)), which may be precoded or unprecoded. The UE115may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (for example, a multi-panel type codebook, a linear combination type codebook, a port selection type codebook). Although these techniques are described with reference to signals transmitted in one or more directions by a base station105, a UE115may employ similar techniques for transmitting signals multiple times in different directions (for example, for identifying a beam direction for subsequent transmission or reception by the UE115) or for transmitting a signal in a single direction (for example, for transmitting data to a receiving device).

A receiving device (for example, a UE115) may try multiple receive configurations (for example, directional listening) when receiving various signals from the base station105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (for example, different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive configurations or receive directions. In some examples, a receiving device may use a single receive configuration to receive along a single beam direction (for example, when receiving a data signal). The single receive configuration may be aligned in a beam direction determined based on listening according to different receive configuration directions (for example, a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

Wireless communications system100may support multicast communications. A base station105may transmit a multicast message to a group of UEs115, and the UEs115may monitor time-frequency resources over which the multicast message is transmitted to attempt to decode the multicast message. The UE115may successfully or unsuccessfully decode the multicast message, and may then transmit feedback to the base station105. The base station105may configure a TA for the UE115, and a UE115in an active mode, such as in an RRC connected mode, may transmit feedback using the TA. The base station105may configure the TA for the UE115once the UE enters the active mode and establishes a connection with the base station105. In some cases, some UEs115may operate in an inactive or idle mode, and may not have an active connection to the base station105. These inactive or idle UEs115may not have a valid TA to use for transmitting messages such as feedback. An inactive or idle UE115may transition to a connected mode in order to obtain a TA before transmitting a message, which may introduce latency and increase power consumed by the UE115.

In some aspects, a UE115in an inactive mode or an idle mode may transmit feedback for multicast communications without transitioning to a connected state. For example, a UE115in an inactive or idle mode may determine resources, such as RACH resources or PUCCH resources, that are available for use by the UE115or a group of UEs115to transmit feedback while in the inactive or idle mode. The base station105may transmit a configuration to the UEs115to convey or indicate to the UEs115the resources available for transmitting multicast feedback.

In some implementations, the base station105may transmit a TA command to the UEs115for use while in an inactive mode or idle mode. In some other implementations, the base station105may transmit a set of TA commands to each UE115. Each TA command may correspond to a respective TA value and a set of channel metrics of one or more cells such as a serving cell for the UE115and one or more neighboring cells of the UE115. The UE115may transmit a feedback message using the TA value corresponding to the TA command associated with the set of channel metrics of the cells to provide feedback for the multicast message. In some cases, the UE115may measure channel metrics at the UE115, and may use the TA value corresponding to the measured channel metrics. In some examples, the base station105or multiple base stations105may perform neural network modeling on various parameters, and the UE115may use the modeling to determine possible TA values for the TA commands.

In some aspects, a UE115may successfully receive a quantity of physical control channels for multicast communications (such as a physical downlink control channel (PDCCH) or other type of physical layer control channel for multicast communications), and a base station105may request status reports from the UEs115indicating the quantity of physical control channels. The base station105may provide the UE115with a resource pool including time and frequency resources, and the UE115may use the resource pool to transmit the status reports. In such cases, if a report indicates that the quantity of physical control channels for multicast communications decoded successfully is less than the quantity of transmitted physical control channels, the base station105may initiate a retransmission of one or more physical control channels for the multicast communications.

FIG.2shows a wireless communications system200that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. In some examples, the wireless communications system200may implement aspects of wireless communications system100. The wireless communications system200may include UEs115and a base station105-a, which may be respective examples of the UEs115and a base station105as described with reference toFIG.1.

One or more UEs115(for example, UE115-aand UE115-c) of a UE group205may be in an active or connected mode (such as an RRC connected mode), in which the UE115and the base station105-aare in active communication and have an established RRC connection. Other UEs, for example, UE115-b, of the UE group205may be in an inactive mode (such as RRC inactive mode), in which the UE115-bmay maintain an RRC connection with the base station105-abut is inactive and minimizes signaling and power consumption. In some other examples, some UEs115in the UE group205, such as the UE115-b, may be in an idle mode (such as an RRC idle mode), in which the UE115-bdoes not have an established RRC connection with the base station105-a.

The wireless communications system200may support multicast communications between the base station105-aand one or more UEs115, such as the UE115-a, the UE115-b, and the UE115-cwithin the UE group205. For instance, the base station105-amay transmit one or more multicast communications210to the UE group205. The base station105-amay configure some UEs115of UE group205to transmit feedback for the multicast communications to the base station105-a. For example, a UE115may successfully decode a transmission and may transmit a respective ACK feedback message indicating a successful decoding, or a UE115may fail to successfully decode a transmission and may transmit a respective NACK feedback message indicating the failed decoding.

In some examples, the UE115-amay operate in a connected mode, and the UE115-amay have a valid TA useable for uplink communications between the UE115-aand the base station105-a. The TA may enable the UE115-ato adjust the timing of an uplink transmission, such as a multicast feedback message, to align with the timing of the base station105-a. The base station105-amay expect the uplink transmission to arrive during an expected duration, and the UE115-amay adjust the timing of the uplink transmission so that the uplink transmission arrives at the base station105-aduring the expected duration. In some cases, other UEs115, such as the UE115-b, operating in an inactive mode or an idle mode, may not have a valid TA. To obtain a valid TA, the UE115-bmay transition to a connected mode with the base station105-a, which takes time and utilizes limited UE resources such as power, among other issues. Without a valid TA, the UE115-bmay misalign transmissions from the UE115-bwith the expected timing at the base station105-a. This may cause the base station105-ato not detect uplink transmissions from the UE115-bdue to the invalid TA (or lack of a TA). The base station105-amay monitor a time window, and an uplink transmission from the UE115-amay arrive before or after the time window. Additionally, or alternatively, the uplink transmissions from the UE115-bmay interfere with other uplink transmissions (such as transmission from other UEs115) sent to the base station105-a.

As described above, aspects of the present disclosure enable UEs115in an idle mode or an inactive mode, such as the UE115-b, to transmit feedback for multicast communications while in the idle mode or inactive mode, that is, without requiring the UEs115to transition to a connected mode, which may reduce power consumption. Additionally, or alternatively, the base station105-amay support various multicast services, and enabling multicast feedback transmission while in an idle mode or an inactive mode may enable the UEs115, such as the UE115-b, to receive or otherwise participate in the various multicast services without necessitating a switch to the connected mode.

To support multicast feedback from UEs115in an inactive or idle mode, the base station105-bmay transmit a feedback configuration message215to the UEs115, including the UE115-b, which the UEs115may use for transmitting feedback (such as feedback message220) for multicast communication210while the UEs115, including UE115-b, are in the inactive mode or the idle mode. The feedback configuration message215may include an indication of resources (including time resources, frequency resources, or spatial resources) for the one or more UEs115, including the UE115-b, to use to transmit multicast feedback. For example, the feedback configuration message215may indicate, to the UE115-b, time and frequency resources usable by the UE115-bto transmit the feedback message220based on whether the UE115-bsuccessfully receives the multicast communication210. In some examples, the base station105-amay transmit the feedback configuration message215to the UE115-bvia a system information block (SIB) or a multicast control channel (MCCH), among other options.

In some examples, the feedback configuration message215may indicate RACH resources or RACH preambles available for the UE115-bto transmit the feedback message220. For example, the base station105-amay indicate one or more physical RACH (PRACH) preambles, and the UE115-bmay select one of the PRACH preambles and transmit the feedback message220using a waveform corresponding to the selected PRACH preamble. The availability of PRACH resources or PRACH preambles may enable the UEs115, including the UE115-b, without a valid TA to transmit feedback for multicast communications including the feedback message220. In some examples, PRACH preambles may utilize a longer cyclic prefix or guard time to account for timing uncertainty and potential interference to other UEs115in the system (for example, UE115-aand UE115-c).

In some implementations, the base station105-amay allocate a pool of PRACH resources or PRACH preambles for the UEs115for use by UEs115in the inactive mode or idle mode, such as the UE115-b, to transmit multicast feedback messages such as the feedback message220. The UE115-bmay report channel metrics, such as reference signal received power (RSRP) thresholds, angular directions (such as altitude and azimuth values associated with one or more beams), beam directions, beam widths, or geographical locations, among other examples, and the base station105-amay allocate the pool of PRACH resources or PRACH preambles based on the channel metrics. In various implementations, one or more UEs, including UE115-b, may use a service, and the base station105-amay allocate the pool of PRACH resources or PRACH preambles based on the service. For example, the base station105-amay allocate a first set of resources or preambles for UEs115using a first service, and may allocate a second set of resources or preambles for UEs115with a specified RSRP value. The UE115-bmay be able to determine (for example, based on the reported channel metrics or the service used) a subset of PRACH resources or PRACH preambles of the feedback resource pool to transmit the feedback message220. In some other implementations, the base station105-amay configure additional RACH occasions for the UE115-bto transmit the feedback message220.

The base station105-amay use information about the allocation of the resource pool to more efficiently transmit retransmissions to the UEs115. For example, if a set of resources or preambles is allocated for use by the UE115-bwhen using a first beam different than the beam originally used to transmit the multicast communication210, and the base station105-areceives the feedback message220from the UE115-bon the set of resources associated with the first beam, the base station105-amay transmit a retransmission of the multicast message using the first beam as opposed to the beam originally used. As an additional example, if the base station105-areceives a NACK in the feedback message220on a resource corresponding to a relatively low RSRP value, the base station105-amay transmit the retransmission with increased power to account for the low RSRP.

In some implementations, the base station105-amay transmit an indication of PUCCH resources allocated for one or more UEs115, including the UE115-b, that may not have a valid TA (such as because they are operating in an inactive or idle mode) to transmit multicast feedback such as the feedback message220. The base station105-amay measure energy levels on the allocated PUCCH resources to determine whether a feedback message220is present. For example, the base station105-amay receive a message on the designated PUCCH resources and may determine if the message exceeds an energy threshold. If so, the base station105-amay determine that a feedback message220has been transmitted on the resources. The UE115-bmay determine a PUCCH format for the feedback message220, which may be a PUCCH format without user multiplexing (for example, format 0, format 1, format 2, or format 3) to enable the base station105-ato use energy detection. The UE115-bmay use other formats by allocating one code division multiplexing (CDM) resource (for example, without invoking multiplexing). The base station105-amay add one or more guard duration resource elements to the time domain, the frequency domain, or both, to minimize interference from the feedback message220with other uplink transmissions. In some examples, the UE115-bmay determine the PUCCH format and may pad the payload of a feedback message220accordingly. For example, if the UE115-buses a PUCCH format other than format 0 or format 1 and has a single bit payload to transmit, the UE115-bmay pad the feedback message220with one or more bits, such as up to three bits, to use PUCCH format 2, PUCCH format 3, or PUCCH format 4.

In some cases, the UE115-bmay not transmit a feedback message220to the base station105-a, and the base station105-amay not have information about the reason for the lack of feedback. In some examples, the base station105-amay configure the UEs115, including the UE115-b, to transmit NACK messages and not ACK messages, and may therefore refrain from transmitting a feedback message220that includes a NACK in response to successfully decoding a physical control channel for a multicast communications and a corresponding multicast message of the multicast communication210. In some examples, the UE115-bmay also refrain from transmitting a feedback message220that includes a NACK after failing to decode a control message. For example, if the UE115-bfails to successfully decode the control message, the UE115-bmay not expect the corresponding multicast message that the control message scheduled. As such, the UE115-bmay not monitor for the multicast message and may not transmit NACK feedback. As a result, the base station105-amay not be aware that the UE115-bfailed to decode the multicast communication210, and accordingly, may determine to not perform a retransmission despite the UE115-bhaving not successfully decoded the multicast communication210.

The UEs115may successfully decide a multicast communications and the base station105-amay not receive NACK feedback, or the one or more UEs115may fail to successfully decode the multicast communications and the base station105-amay not receive NACK feedback. To enable the base station105-ato differentiate between these cases, the base station105-amay provide the UEs115, including the UE115-b, with a resource pool including time and frequency resources that the UEs115may use to transmit reception status reports. For example, the base station105-amay allocate a resource pool to the UE115-band the UE115-bmay transmit a message using at least a subset of the resources in the resource pool to indicate a quantity of physical control channels for multicast communications successfully decoded by the UE115-b. In some implementations, the resource pool may include or consist of one or both of a set of PRACH resources or a set of PUCCH resources. Further, the base station105-amay configure the UE115-bto monitor one or more multicast time occasions and may transmit, to the base station105-a, an indication of the number of physical control channels for multicast communications that have been successfully decoded during the one or more time occasions. For example, the UE115-bmay receive, from the base station105-a, a multicast grant that schedules a quantity of multicast time occasions for the UE115-b, over which a base station105-amay choose to transmit multicast messages. The UE115-bmay monitor the multicast time occasions and may receive, from the base station105-a, a quantity of physical control channels for multicast communications during one or more of the scheduled multicast time occasions. For example, the UE115-bmay receive one or more of the physical control channels, or in some cases the UE115-bmay not receive any physical control channels. The UE115-bmay select resources from the allocated resource pool, and may then transmit, using the resources, an indication of the quantity of transmissions that have been successfully decoded. Based on the indication, the base station105-amay compare the number of physical control channels transmitted to the UE115-bwith the number of physical control channels that the UE115-bhas indicated as successfully decoded. If a report from the UE115-bindicates that the quantity of physical control channels successfully decoded is less than the quantity of those transmitted by the base station105-a, the base station105-amay determine that a lack of NACK(s) from the UE115-bis a result of the UE115-bfailing to decode one or more of the physical control channels for multicast communications, which may trigger the base station105-ato initiate a retransmission.

In some implementations, the base station105-amay configure the UE115-bwith a given resource pool based on the quantity of physical control channels of each reception status report. For example, the UE115-bmay decode the quantity of physical control channels, and the base station105-amay select a first resource pool if a metric based on the quantity of physical control channels out of the total quantity of transmitted physical control channels satisfies a threshold (for example, if a ratio of the quantity of decoded physical control channels to the total quantity of transmitted physical control channels is greater than a threshold). Similarly, the base station105-amay select a second resource pool if the metric fails to satisfy a threshold (for example, if the ratio of the quantity of decoded physical control channels to the total quantity of transmitted physical control channels is less than a threshold). Each resource pool may correspond to different multicast resources (time or frequency resources), services, or channel types, among other examples.

Typically, the probability that the base station105-areceives at least one NACK after a multicast communication increases (in some cases non-linearly) with the number of UEs115seeking to receive the multicast communication. As such, the base station105-amay count or otherwise determine or estimate the quantity of UEs115in the inactive mode or the idle mode presently accepting multicast communications (for example, the quantity of inactive or idle UEs115in UE group205). By knowing the number of UEs115in the inactive or idle mode, the base station105-amay make better use of any multicast feedback.

In some examples, the base station105-amay perform multicast communications for different services (for example, MBMS, enhanced MBMS, among others). However, not all UEs115may have the capability to receive all services. For example, a UE115-bmay support a service while in a connected mode, but may not support the same service while in an inactive or idle mode. In some aspects, the base station105-amay broadcast a counting duration for each offered multicast service and an indication of a resource pool (for example, including PUCCH or PRACH resources) on which to transmit a response. The base station105-amay then count the number of UEs115in inactive or idle mode that are accepting multicast communications of a given service via the broadcast. During each counting duration, a UE115in the idle mode or the inactive mode, such as the UE115-b, may transmit, using resources from the indicated resource pool, a service request message indicating an interest of the UE115-bin receiving the service. The base station105-amay count, determine, or estimate the number of UEs115in inactive or idle mode that are monitoring for each multicast service based on the number of received service request messages for respective multicast services. In some cases, the base station105-amay receive a number of feedback messages220and may determine that a number of UEs115are in inactive or idle mode. The base station105-amay compare the number of feedback messages to the number of UEs115to determine whether to retransmit one or more multicast messages.

In some examples, the base station105-amay not configure an identifier for a UE115-bin inactive or idle mode for communications with the base station105-a, such as a radio network temporary identifier (RNTI) or cell RNTI (C-RNTI). In order for the base station105-ato identify which UE115has transmitted a service request message, the UE115-bmay use an identifier of the UE115-bto transmit the service request message. For example, the UE115-bmay hash the service request message with a device identifier of the UE115-b(for example, based on a hash function or hash code corresponding to the device identifier) and transmit the hashed service request message to the base station105-a.

In some examples, to reduce system overhead, the base station105-amay not count every inactive UE115or idle UE115. Instead, the base station105-amay configure each inactive UE115or idle UE115with a probability indicator. In some examples, a percentage associated with a probability of transmitting multicast feedback (such as 1%, 2%, 5%, or 10%, among other examples) may represent, or be representative of, each probability indicator. Each of the UEs115may transmit the service request message in one or more counting durations. In some cases, the UEs115may transmit the service request message according to the probability indicator. For example, each of the UEs115may consider the probability indicator when determining whether to transmit the service request message. As an example, for every 100 counting durations, a UE115(such as UE115-b) with a probability indicator of 10% may transmit 10% of the time (for example, the UE115-bmay transmit a service request message in 10 of the 100 counting durations). This may enable the base station105-ato count the UEs115that transmit a service request message and to use the probability indicator to estimate the total quantity of UEs115the base station105-amay support. In some cases, the total quantity of UEs115may include UEs in a connected mode and UEs in an inactive mode.

FIG.3illustrates an example of a wireless communications system300that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. In some examples, the wireless communications system300may implement aspects of the wireless communications systems100or200. The wireless communications system300may include UEs115and base stations105, which may be respective examples of UEs115and base stations105as described with reference toFIG.1.

The wireless communications system300may support multiple TA commands for UEs115to use while in an inactive or idle mode for transmitting feedback for multicast messages. In some implementations, a base station105-bmay determine that UEs in an inactive or idle mode may use a set of TA commands, transmit the TA command to one or more UEs115, and receive feedback from one or more UEs115according to a TA command of the set of TA commands.

In some implementations, a base station105-bmay determine one or more TA commands based on a number of factors. The factors may include historical data or information such as previously configured TA commands, information associated with neighboring or serving cells (for example, a relative delay between the serving cell and one or more neighboring cells), information from other wireless devices such as other UEs in the wireless communications system300, RSRP, a geographical location or topography in which the wireless communications system300operates, or the position of the UE115, among other examples.

For example, the base station105-bmay determine a first TA command for a UE115, such as a UE115-f, based on a position of the UE115-fwith respect to the base station105-b, or a base station105-c, or both. The base station105-cmay determine a TA command for a UE115, such as a UE115-e, based on the position of the UE115-ewith respect to the base station105-b, or a base station105-c, or both, and the base station105-cmay determine a TA command for a UE115, such as a UE115-d, based on the position of the UE115-dwith respect to the base station105-c, or a base station105-d, or both.

In some implementations, the base station105-b(or another base station105in the wireless communications system300) may determine a set of TA commands based on a set of channel metrics or system conditions (such as geographical location, environment, topography, quantity of users, quantity of and location of interfering objects such as buildings, among others). For example, the base station105-bmay provide a TA command having a TA value that corresponds to one or more channel metrics or positioning between the UE115-fand one or more cells, such as a serving cell (which may be supported by base station105-b), a neighboring cell (which may be supported by base station105-c), or both. For instance, the base station105-bmay configure TA command 0 for use by UE115-fin an inactive or idle mode if the serving cell RSRP (which the base station105-bmay support) is within a range of [X00, Y00] dB, neighboring cell 1 RSRP (which the base station105-cmay support) is within a range of [X01, Y01] dB, and neighboring cell 2 RSRP (which the base station105-dmay support) is within a range of [X02, Y02] dB, and so on. The base station105-bmay also configure TA command 1 for another set of channel metrics if serving cell RSRP is within a range of [X10, Y10] dB, neighboring cell 1 RSRP is within a range of [X11, Y11] dB, and neighboring cell 2 RSRP is within a range of [X12, Y12] dB.

In some examples, a base station105-b(or another base station105in the wireless communications system300) may configure one or more TA commands based on a relative delay between a serving cell and a neighboring cell. For instance, base station105-bmay configure a first TA command if the relative delay between the serving cell (which the base station105-bmay support) and a neighboring cell (such as a neighboring cell which the base station105-cmay support) is within a time range of [0, T0], and a second TA command if the relative delay between the serving cell (which the base station105-bmay support) and a neighboring cell (such as a neighboring cell which the base station105-cmay support) is within a time range of [T0, T1], and so on.

In some implementations, a base station105-b(or another base station105in the wireless communications system300) may configure one or more TA commands based on positioning ranges. For instance, base station105-bmay configure a first TA command for UE115-fif the UE115-fis within a positioning range 0, a second TA command for UE115-fis the UE115-fis within a positioning range 1, and so on.

The base station105-bmay determine a set of TA commands based on channel metrics, positions, or other conditions, and may broadcast, to the UEs115, the set of TA commands. In some examples, the base station105-bmay transmit the set of TA commands and values via a feedback configuration message215, as described with reference toFIG.2. A UE115(for example, UE115-f) in the inactive mode or the idle mode may receive the set of TA commands, and may determine a channel metric, position, or other condition of the UE115-f. The UE115-fmay determine a TA command based on the determined channel metric, position or other condition, and may use the TA command to transmit a feedback message for multicast communications while in an inactive or idle mode. For instance, the UE115-fmay measure a set of channel metrics and based on the measured channel metrics, apply a TA value that corresponds to the TA command associated with the measured channel metrics to transmit a feedback message. In some cases, the UE115-fmay transmit the feedback message via PUCCH.

As the channel metrics, position, or other conditions of devices within the wireless communications system300change, the UEs115transmitting feedback for multicast communications while in an inactive or idle mode may use different TA commands. For example, the UE115-fmay move within a coverage area of a base station105-b, or environmental conditions, number of active users, or other factors may channel quality. Accordingly, the UE115-fmay periodically reassess current conditions (for example, UE115-fmay remeasure the set of channel metrics) and may determine a TA command based on the current conditions. As an example, the UE115-fmay change position relative to the base station105-band the base station105-c, and may apply a TA command corresponding to the new position of the UE115-ffor subsequent feedback messages for multicast communications while the UE115-fis in the inactive or idle mode.

FIG.4illustrates an example of a wireless communications system400that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. In some examples, the wireless communications system400may implement aspects of the wireless communications systems100,200, or300. The wireless communications system400may include a UE115-gand base station105-e, which may be respective examples of a UE115and a base station105as described with reference toFIG.1.

A UE may determining a TA command or TA values based on different channel metrics or positioning information of UEs115within a system, which may be computationally complex, may be associated with a high signaling overhead, or may consume storage or other resources at a UE. To reduce the signaling overhead, storage limitations, and other issues, wireless communications system400may support neural network modeling for determining TA commands. For example, a base station105-emay utilize a neural network model and determine an associated set of neural network parameters to determine one or more TA commands. The UE115-gmay use the one or more TA commands for transmitting feedback for multicast communications while in an inactive or idle mode.

In some implementations, the base station105-emay determine a neural network modeling algorithm that represents a statistical model for TA commands based on a neural network modeling algorithm and other data available at the base station105-e. For instance, the base station105-emay utilize historical data (previously configured TA values, positioning data of the UE115-gor other UEs, among others) or information from neighboring devices or cells to calculate TA values for a set of TA commands, such as the TA commands as described with reference toFIG.3. In some implementations, the base station105-amay indicate, or the UE115-gmay determine, parameters such as channel metrics or positioning information, and the base station105-emay base the neural network model on the parameters. For example, the base station105-emay indicate a neural network model, a set of neural network parameters, or both to the UE115-gvia communication link410. The UE115-gmay determine input parameters, such as measured channel metrics at the UE115-g, positioning information at the UE115-g, among others, and determine a TA command to use for transmitting feedback for multicast communications using the neural network model and neural network parameters that the base station105-emay indicate. After receiving a multicast message via communication link410, the UE115-gmay transmit a feedback message (such as a feedback message220as described with reference toFIG.2) using the determined TA command.

As an example, at420, the base station105-emay determine the neural network model that the base station105-emay base on static (elevation, geography, or base station position, among other examples) and dynamic (weather, RSRP, or UE position, among other examples) conditions. The conditions may be parameters for the model and may correspond to a set of TA commands, such as the TA commands as described with reference toFIG.3. At425, the base station105-emay determine the parameters for a neural network model that may represent the TA commands. At430, the base station105-emay transmit an indication of the neural network model and the neural network parameters via the communication link410to the UE115-g. In some examples, the base station105-emay transmit the neural network model and the neural network parameters along with a TA command for the UE115-gin an active or connected mode, or the base station105-emay include the neural network model and the neural network parameters in a configuration message (such as feedback configuration message215as described with reference toFIG.2).

At435, the UE115-gmay receive the neural network model and the neural network parameters and based on the neural network model and the neural network parameters may determine a TA command to use to transmit feedback for multicast communications while in an inactive or idle mode at440. In some examples, at440, the UE115-gmay determine UE specific parameters to input to the model (for example, the UE115-gmay measure channel metrics, current position), and at445, the UE115-gmay transmit feedback to the base station105-eaccording to the determined TA value.

At various times and for a variety of reasons, the UE115-gmay transition from an inactive or idle mode to an active or connected mode, while which the UE115-gmay receive an updated neural network model and neural network parameters from the base station105-e. The UE115-gmay base the updated model and parameters on the additional data accumulated, analyzed, or otherwise processed while the UE115-gwas in the inactive or idle mode.

FIG.5illustrates an example of a process flow500that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. In some examples, process flow500may implement aspects of wireless communications systems100,200,300, or400. The process flow500may include a UE115-hand a base station105-f, which may be respective examples of a UE115and a base station105. Alternative examples of the following may be implemented, in which some processes are performed in a different order than described or are not performed at all. In some implementations, processes may include additional features not mentioned below, or further processes may be added.

At505, the UE115-hmay optionally transmit, to the base station105-f, an indication of channel quality information, which may include one or more channel metrics measured by the UE115-h. For example, the UE115-hmay indicate a signal strength, an angle, a beam identification, or a location of the UE115-h.

At510, the base station105-fmay optionally determine resources for the UE115-hto use for transmitting feedback for multicast communications while the UE115-his in an inactive or idle mode. In some implementations, the base station105-fmay determine the resources based on the channel metrics. The resources may be PRACH resources or preambles, PUCCH resources, among others. In some examples, the base station105-fmay determine a set of resources (for example, a pool of resources) to designate for feedback transmissions from the UE115-h.

In some examples, at515, the base station105-fmay determine one or more TA commands for the UE115-h. The base station105-fmay base the TA commands on channel metrics (for example, the channel quality information transmitted at505). For example, each TA command may correspond to a set of channel metrics and a corresponding TA value.

At520, the base station105-fmay transmit, to the UE115-h, a feedback configuration message. The feedback configuration message may be an example of a feedback configuration message215as described with reference toFIG.2. In some examples, the feedback configuration message may include the one or more TA commands determined at515. Additionally, or alternatively, the feedback configuration message may include an indication of the resources determined at510.

At525, the base station105-fmay optionally transmit the determined TA commands to the UE115-h. For example, the base station105-fmay optionally transmit one or more TA commands at525if the TA commands are not included in the feedback configuration message at520.

At530, the base station105-fmay optionally transmit an indication of or associated with a neural network model and neural network parameters for determining TA commands or TA values. For instance, in some implementations, the base station105-fmay utilize a neural network to determine the one or more TA commands (for example, at515), and in such cases, the base station105-fmay determine a neural network model and associated parameters that the base station105-fmay use to calculate a TA command or TA value for the UE115-hto use for transmitting feedback for multicast communications while in an inactive or idle mode. The base station105-fmay determine the neural network model based on historical data, or other parameters.

At535, the UE115-hmay determine a TA command or TA value to use for transmitting feedback for multicast communications. In some implementations, the UE115-hmay use the neural network model, neural network parameters, and, in some cases, UE-specific parameters, to determine the TA command to use for multicast feedback while in an inactive or idle mode. In other examples, the base station105-fmay transmit one or more TA commands at525, and the UE115-hmay use the one or more TA commands to determine a TA value to use for multicast feedback.

At540, the UE115-hmay monitor for multicast communications from the base station105-f. The base station105-fmay, in some cases, transmit a multicast control channel via a set of resources allocated for multicast communications. The multicast control channel may indicate scheduling information for multicast communications. If the UE115-hsuccessfully receives the multicast control channel, the UE115-hmay determine resources scheduled for the multicast communications and may monitor the determined resources for the multicast communications from the base station105-fat545.

Optionally, at550, the UE115-hmay determine resources to use to transmit a feedback message to the base station105-fin response to the multicast communication. For example, the UE115-hmay determine the resources based on channel metrics, or the base station105-fmay transmit the feedback configuration message at520that may indicate the resources. The resources may include PRACH resources or preambles, PUCCH resources, among others.

At555, the base station105-fmay monitor the multicast control channel for a feedback message from the UE115-h. At560, the UE115-hmay transmit the feedback message to the base station105-fover the multicast control channel and using the determined resources.

FIG.6illustrates an example of a process flow600that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. In some examples, process flow600may implement aspects of wireless communications systems100,200,300, or400. The process flow600may include a UE115-iand a base station105-g, which may be respective examples of a UE115and a base station105. Alternative examples of the following may be implemented, in which some processes are performed in a different order than described or are not performed at all. In some implementations, processes may include additional features not mentioned below, or further processes may be added.

At605, the base station105-gmay optionally determine resources for the UE115-fto use for a feedback message. In some implementations, the base station105-gmzy determine the resources based on the channel metrics. The resources may be PRACH resources or preambles, PUCCH resources, among others. In some examples, the base station105-gmay determine a set of resources (for example, a pool of resources) to designate for feedback transmissions from the UE115-i.

At610, the base station105-gmay transmit, to the UE115-i, a feedback configuration message. The feedback configuration message may be an example of a feedback configuration message215as described with reference toFIG.2. In some examples, the feedback configuration message may include an indication of the resources determined at605. The feedback configuration message may include an indication for the UE115-ito transmit a reception status report. In other examples, the base station105-gmay transmit the indication for the UE115-ito transmit a reception status report in a message separate from the feedback configuration message.

In some implementations, at615, the UE115-imay monitor for one or more multicast communications via one or more multicast occasions.

At620, the base station105-gmay transmit one or more physical control channels for multicast communications during the one or more multicast occasions. The physical control channels for multicast communications may include scheduling information for a multicast message.

At625, the UE115-imay transmit a reception status report to the base station105-g. The reception status report may include a quantity of physical control channels for multicast communications decoded at the UE115-i, a quantity of multicast occasions monitored by the UE115-i, a ratio between the quantity of physical control channels received and the quantity of physical control channels transmitted by the base station105-g, among other information.

At630, the base station105-gmay transmit, to the UE115-i, a counting duration indication specifying a counting duration for one or more services of multicast communications supported by the base station105-g. The counting duration indication may, in some examples, include an indication of a resource or resource pool for the UE115-ito transmit a service request message in response to the base station105-gduring the counting duration.

At635, the base station105-gmay optionally transmit a probability indicator to the UE115-i. The probability indicator may specify a probability in which the UE115-iis to transmit a service request message in response during the counting duration.

At640, in response to the counting duration indication transmitted at630, the UE115-imay transmit a service request message indicating interest in receiving a service. The UE115-I may transmit the service request message on the indicated resource or resource pool and, in some examples, may transmit the service request message according to the probability indicator received at635.

At645, the base station105-gmay determine the quantity of UEs requesting the given multicast service. For example, the base station105-gmay monitor the counting duration for service request messages from one or more UEs including the UE115-i, and determine the quantity of UEs (inactive or otherwise) requesting a given multicast service. In some implementations, the base station105-gmay determine the quantity of UEs based on the probability indicator transmitted at635. For instance, if probability indicator is 1%, and the base station105-greceives1service request message at640(from UE115-ifor example), the base station105-gmay determine that because only 1% of the UEs (according to the probability indicator) transmitted a service request message, approximately 100 UEs are requesting the multicast service.

FIG.7shows a block diagram of a device705that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device705may be an example of aspects of a UE115. The device705may include a receiver710, a communications manager715, and a transmitter720. The communications manager715may be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses).

The receiver710may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to feedback for multicast transmissions). Information may be passed on to other components of the device705. The receiver710may be an example of aspects of the transceiver described with reference toFIG.8. The receiver710may utilize a single antenna or a set of antennas.

The communications manager715may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station, monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station, and transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The communications manager715may be an example of aspects of the communications manager815described herein.

The transmitter720may transmit signals generated by other components of the device705. In some examples, the transmitter720may be collocated with a receiver710in a transceiver component. For example, the transmitter720may be an example of aspects of the transceiver described with reference toFIG.8. The transmitter720may utilize a single antenna or a set of antennas.

In some examples, the communications manager715may be implemented as an integrated circuit or chipset for a mobile device modem, and the receiver710and transmitter720may be implemented as analog components (for example, amplifiers, filters, antennas) coupled with the mobile device modem to enable wireless transmission and reception over one or more bands.

The communications manager715may be implemented to realize one or more potential advantages. One implementation may allow the device705to provide feedback for multicast communications while in an inactive or idle mode or in other scenarios in which the device705does not have a valid or configured TA to use for transmitting feedback. Based on the techniques for multicast feedback between the device705and a base station, the device705may be capable of providing feedback that it otherwise may not have been able to provide without having to transition a connected mode to obtain a valid TA, which may utilize limited resources such as power and battery life at the device705. The ability to transmit feedback for multicast communications in an idle or inactive mode may also increase the likelihood of receiving retransmissions successfully.

FIG.8shows a block diagram of a device805that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device805may be an example of aspects of a device705, or a UE115. The device805may include a receiver810, a communications manager815, and a transmitter835. The communications manager815may be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses).

The receiver810may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to feedback for multicast transmissions). Information may be passed on to other components of the device805. The receiver810may be an example of aspects of the transceiver described with reference toFIG.8. The receiver810may utilize a single antenna or a set of antennas.

The communications manager815may be an example of aspects of the communications manager715. The communications manager815may include a configuration receiver820, a multicast monitor825, and a feedback transmitter830.

The configuration receiver820may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station.

The multicast monitor825may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station.

The feedback transmitter830may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring.

The transmitter835may transmit signals generated by other components of the device805. In some examples, the transmitter835may be collocated with a receiver810in a transceiver component. For example, the transmitter835may be an example of aspects of the transceiver described with reference toFIG.8. The transmitter835may utilize a single antenna or a set of antennas.

FIG.9shows a block diagram of a communications manager905that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The communications manager905may include a configuration receiver910, a multicast monitor915, a feedback transmitter920, a resource manager925, a preamble selector930, a channel quality transmitter935, a format component940, a TA receiver945, a measurement component950, a neural network receiver955, a TA component960, a status report transmitter965, an indication transmitter970, a broadcast receiver975, a message transmitter980, and a probability receiver985. Each of these components may communicate, directly or indirectly, with one another (for example, via one or more buses).

The configuration receiver910may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. In some examples, the configuration receiver910may receive system information or a multicast control channel that indicates the one or more configurations.

The multicast monitor915may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. In some examples, the multicast monitor915may receive a multicast message over the set of time-frequency resources based on the monitoring, in which selecting the preamble of the set of RACH preambles includes selecting the preamble based on a channel quality metric associated with the received multicast message.

In some examples, the multicast monitor915may receive a multicast message over the set of time-frequency resources based on the monitoring. In some examples, the multicast monitor915may monitor multiple time occasions for multicast transmissions from the base station. In some examples, the multicast monitor915may receive a set of physical control channels for multicast transmissions based on the monitoring of the multiple time occasions.

The feedback transmitter920may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. In some examples, the feedback transmitter920may pad a payload of the one or more multicast feedback messages based on a size associated with the uplink control format. In some examples, the feedback transmitter920may transmit the one or more multicast feedback messages based on an absence of reception of a multicast transmission over the set of time-frequency resources during the monitoring, in which the one or more multicast feedback messages include a negative acknowledgement feedback message.

In some examples, the feedback transmitter920may transmit the one or more multicast feedback messages based on reception of a multicast transmission over the set of time-frequency resources during the monitoring, in which the one or more multicast feedback messages include an acknowledgement feedback message. In some examples, the feedback transmitter920may refrain from transmitting the one or more multicast feedback messages in accordance with a timing advance value of the UE.

The resource manager925may determine a set of RACH resources available for multicast feedback based on a resource allocation indicated by the one or more configurations, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages via the set of RACH resources. In some examples, the resource manager925may determine a set of RACH preambles available for multicast feedback based on a resource allocation indicated by the one or more configurations.

In some examples, the resource manager925may determine time-frequency resources for multicast feedback based on the channel quality information, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages via the determined time-frequency resources. In some examples, the resource manager925may determine a resource pool available for multicast feedback based on the one or more configurations, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using a subset of time-frequency resources of the resource pool.

In some examples, the resource manager925may determine a set of PUCCH resources available for multicast feedback based on the one or more configurations, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using a subset of the PUCCH resources. In some examples, the resource manager925may determine a set of uplink resources available for a reception status report associated with multicast transmissions from the base station. In some implementations, the set of uplink resources includes RACH resources or uplink control channel resources.

The preamble selector930may select a preamble of the set of RACH preambles, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using the selected preamble.

The channel quality transmitter935may transmit channel quality information associated with the received multicast message. In some implementations, the channel quality information includes one or more of reference signal received power, beam direction, beam width, geographical location, or altitude and azimuth values associated with one or more beams.

The format component940may determine an uplink control format for the one or more multicast feedback messages.

The TA receiver945may receive a timing advance command from the base station, the timing advance command indicating a timing advance for use by the UE while in the inactive mode or the idle mode, in which the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE. In some examples, the TA receiver945may receive a second timing advance command from the base station, the second timing advance command indicating a second timing advance for use by the UE while in the inactive mode or the idle mode, in which the second timing advance command corresponds to second set of values for one or more channel metrics associated with the UE and associated with one or more cells including the serving cell for the UE. In some examples, the TA receiver945may receive one or more of the timing advance command or the second timing advance command in the one or more configurations, the one or more configurations indicating a set of uplink resources for multicast feedback, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using the set of uplink resources. In some implementations, the one or more channel metrics include one or more of a reference signal received power, a relative delay between the serving cell and one or more other cells, or a positioning range of the UE.

The measurement component950may measure a set of channel metrics of the one or more cells including the serving cell, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using the timing advance based on the set of channel metrics satisfying the first set of values or using the second timing advance based on the set of channel metrics satisfying the second set of values.

The neural network receiver955may receive a set of neural network parameters in the timing advance command from the base station, in which the set of neural network parameters indicate the timing advance. In some examples, the neural network receiver955may receive, at the UE while in a connected mode, a neural network model and a set of neural network parameters from the base station, the neural network model and the set of neural network parameters being associated with a neural network for a timing advance. In some examples, the neural network receiver955may receive one or more neural network parameters from the base station.

The TA component960may determine the timing advance based on the neural network model, the set of neural network parameters, and the one or more neural network parameters, in which transmitting the one or more multicast feedback messages includes transmitting, by the UE while in the inactive mode or the idle mode, the one or more multicast feedback messages based on the timing advance.

The status report transmitter965may transmit the reception status report using the set of uplink resources.

The indication transmitter970may transmit an indication of a quantity of the received set of physical control channels for multicast transmissions in the reception status report. In some examples, the indication transmitter970may transmit, in the reception status report, a ratio between the quantity of the received set of physical control channels for multicast transmissions and a total quantity of physical control channels for multicast transmissions transmitted over the multiple time occasions. In some implementations, the total quantity of physical control channels for multicast transmissions corresponds to a set of uplink control channel resources.

The broadcast receiver975may receive a broadcast message from the base station indicating a counting duration for a service of the multicast transmissions supported by the base station.

The message transmitter980may transmit a message over the counting duration requesting the service of the multicast transmissions supported by the base station. In some examples, the message transmitter980may transmit the message based on an identifier of the UE. In some examples, the message transmitter980may transmit the message in accordance with the probability indicator. In some implementations, the message includes an uplink control channel message or a RACH message.

The probability receiver985may receive, from the base station, a probability indicator for the UE.

FIG.10shows a diagram of a system including a device1005that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device1005may be an example of or include the components of device705, device805, or a UE115. The device1005may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager1010, an I/O controller1015, a transceiver1020, an antenna1025, memory1030, and a processor1040. These components may be in electronic communication via one or more buses (for example, bus1045).

The communications manager1010may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station, monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station, and transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring.

The I/O controller1015may manage input and output signals for the device1005. The I/O controller1015may also manage peripherals not integrated into the device1005. In some implementations, the I/O controller1015may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller1015may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operating system. In other cases, the I/O controller1015may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some implementations, the I/O controller1015may be implemented as part of a processor. In some implementations, a user may interact with the device1005via the I/O controller1015or via hardware components controlled by the I/O controller1015.

In some implementations, the device1005may include a single antenna1025, or the device1005may have more than one antenna1025, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The processor1040may include an intelligent hardware device, (for example, a general-purpose processor, a DSP, a central processing unit (CPU), a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some implementations, the processor1040may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor1040. The processor1040may be configured to execute computer-readable instructions stored in a memory (for example, the memory1030) to cause the device1005to perform various functions (for example, functions or tasks supporting feedback for multicast transmissions).

The code1035may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code1035may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some implementations, the code1035may not be directly executable by the processor1040but may cause a computer (for example, when compiled and executed) to perform functions described herein.

FIG.11shows a block diagram of a device1105that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device1105may be an example of aspects of a base station105. The device1105may include a receiver1110, a communications manager1115, and a transmitter1120. The communications manager1115may be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses).

The receiver1110may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to feedback for multicast transmissions). Information may be passed on to other components of the device1105. The receiver1110may be an example of aspects of the transceiver described with reference toFIG.12. The receiver1110may utilize a single antenna or a set of antennas.

The communications manager1115may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode, transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications, and monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations. The communications manager1115may be an example of aspects of the communications manager1215described herein.

The transmitter1120may transmit signals generated by other components of the device1105. In some examples, the transmitter1120may be collocated with a receiver1110in a transceiver component. For example, the transmitter1120may be an example of aspects of the transceiver described with reference toFIG.12. The transmitter1120may utilize a single antenna or a set of antennas.

FIG.12shows a block diagram of a device1205that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device1205may be an example of aspects of a device1105, or a base station105. The device1205may include a receiver1210, a communications manager1215, and a transmitter1235. The communications manager1215may be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses).

The receiver1210may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to feedback for multicast transmissions). Information may be passed on to other components of the device1205. The receiver1210may be an example of aspects of the transceiver described with reference toFIG.12. The receiver1210may utilize a single antenna or a set of antennas.

The communications manager1215may be an example of aspects of the communications manager1115. The communications manager1215may include a configuration transmitter1220, a multicast transmitter1225, and a feedback monitor1230. The communications manager1215may be an example of aspects of the other communications managers described herein.

The configuration transmitter1220may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode.

The multicast transmitter1225may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications.

The feedback monitor1230may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations.

The transmitter1235may transmit signals generated by other components of the device1205. In some examples, the transmitter1235may be collocated with a receiver1210in a transceiver component. For example, the transmitter1235may be an example of aspects of the transceiver described with reference toFIG.12. The transmitter1235may utilize a single antenna or a set of antennas.

FIG.13shows a block diagram of a communications manager1305that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The communications manager1305may include a configuration transmitter1310, a multicast transmitter1315, a feedback monitor1320, a resource transmitter1325, a channel quality receiver1330, a resource pool component1335, a TA transmitter1340, a neural network transmitter1345, a report receiver1350, a broadcast transmitter1355, a service monitor1360, and a probability transmitter1365. Each of these components may communicate, directly or indirectly, with one another (for example, via one or more buses).

The configuration transmitter1310may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode. In some examples, the configuration transmitter1310may transmit system information or a multicast control channel that indicates the one or more configurations.

The multicast transmitter1315may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications.

The feedback monitor1320may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations. In some examples, the feedback monitor1320may monitor the set of RACH resources for the one or more multicast feedback messages. In some aspects, the feedback monitor1320may monitor for the one or more multicast feedback messages based on the set of RACH preambles. In some implementations, the feedback monitor1320may receive the one or more multicast feedback messages via a subset of time-frequency resources of the resource pool based on the monitoring. In some examples, the feedback monitor1320may monitor the set of PUCCH resources for the one or more multicast feedback messages.

In some examples, the feedback monitor1320may receive, based on the monitoring, the one or more multicast feedback messages according to the timing advance based on a set of channel metrics at the UE satisfying the first set of values or according to the second timing advance based on a set of channel metrics at the UE satisfying the second set of values. In some aspects, the feedback monitor1320may receive the one or more multicast feedback messages via the set of uplink resources. In some implementations, the feedback monitor1320may receive, from the UE in the inactive mode or the idle mode, the one or more multicast feedback messages based on the timing advance, the timing advance based on the one or more neural network parameters. In some examples, the feedback monitor1320may receive the one or more multicast feedback messages based on the monitoring, in which the one or more multicast feedback messages includes a negative acknowledgement feedback message. In some aspects, the feedback monitor1320may receive the one or more multicast feedback messages based on the monitoring, in which the one or more multicast feedback messages includes an acknowledgement feedback message.

The resource transmitter1325may transmit an indication of a set of RACH resources available for multicast feedback in the one or more configurations. In some examples, the resource transmitter1325may transmit an indication of a set of RACH preambles available for multicast feedback in the one or more configurations. In some implementations, the resource transmitter1325may transmit an indication of the resource pool in the one or more configurations. In some examples, the resource transmitter1325may transmit an indication of a set of PUCCH resources available for multicast feedback in the one or more configurations. In some aspects, the resource transmitter1325may transmit an indication of the set of uplink resources in the one or more configurations.

The channel quality receiver1330may receive, from the UE, channel quality information associated with a multicast channel used for multicast communications with the UE. In some examples, the channel quality information includes one or more of reference signal received power, beam direction, beam width, geographical location, or altitude and azimuth values associated with one or more beams. In some aspects, the one or more channel metrics includes one or more of a reference signal received power, a relative delay between the serving cell and one or more other cells, or a positioning range of the UE.

The resource pool component1335may determine a resource pool for multicast feedback for the UE based on the channel quality information. In some examples, the resource pool component1335may determine a set of uplink resources available for a reception status report associated with multicast transmissions from the base station.

The TA transmitter1340may transmit a timing advance command to the UE, the timing advance command indicating a timing advance for the UE in the inactive mode or the idle mode, in which the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE.

In some examples, the TA transmitter1340may transmit a second timing advance command to the UE, the second timing advance command indicating a second timing advance for the UE in the inactive mode or the idle mode, in which the second timing advance command corresponds to second set of values for one or more channel metrics associated with the UE and associated with one or more cells including the serving cell for the UE. In some implementations, the TA transmitter1340may transmit one or more of the timing advance command or the second timing advance command in the one or more configurations, in which the one or more configurations indicates a set of uplink resources for multicast feedback.

The neural network transmitter1345may transmit a set of neural network parameters to the UE, in which the set of neural network parameters indicate the timing advance. In some examples, the neural network transmitter1345may transmit, to the UE in a connected mode, a neural network model and a set of neural network parameters associated with a neural network for a timing advance. In some examples, the neural network transmitter1345may transmit one or more neural network parameters to the UE.

The report receiver1350may receive the reception status report from the UE over the set of uplink resources. In some examples, the report receiver1350may receive, in the reception status report, a quantity of physical control channels for multicast transmissions received by the UE. In some examples, the report receiver1350may receive, in the reception status report, a ratio between the quantity of the physical control channels for multicast transmissions received by the UE and a total quantity of physical control channels for multicast transmissions transmitted over multiple time occasions of the set of uplink control channel resources. In some implementations, the set of uplink resources includes RACH resources or uplink control channel resources.

The broadcast transmitter1355may transmit a broadcast message indicating a counting duration for a service of multicast transmissions supported by the base station.

The service monitor1360may monitor, during the counting duration, for one or more messages from the UE requesting the service of multicast transmissions supported by the base station. In some examples, the service monitor1360may receive the one or more the messages based on an identifier of the UE. In some examples, the service monitor1360may receive the one or more the messages based on the probability indicator of the UE. In some implementations, the one or more messages includes an uplink control channel message or a RACH message.

The probability transmitter1365may transmit, to the UE, a probability indicator for the UE.

FIG.14shows a diagram of a system including a device1405that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The device1405may be an example of or include the components of device1105, device1205, or a base station105. The device1405may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager1410, a network communications manager1415, a transceiver1420, an antenna1425, memory1430, a processor1440, and an inter-station communications manager1445. These components may be in electronic communication via one or more buses (for example, bus1450).

The communications manager1410may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode, transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications, and monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations.

The network communications manager1415may manage communications with the core network (for example, via one or more wired backhaul links). For example, the network communications manager1415may manage the transfer of data communications for client devices, such as one or more UEs115.

In some implementations, the device1405may include a single antenna1425, or the device1405may have more than one antenna1425, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory1430may include RAM, ROM, or a combination thereof. The memory1430may store computer-readable code1435including instructions that, when executed by a processor (for example, the processor1440) cause the device to perform various functions described herein. In some implementations, the memory1430may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor1440may include an intelligent hardware device, (for example, a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some implementations, the processor1440may be configured to operate a memory array using a memory controller. In some implementations, a memory controller may be integrated into processor1440. The processor1440may be configured to execute computer-readable instructions stored in a memory (for example, the memory1430) to cause the device1405to perform various functions (for example, functions or tasks supporting feedback for multicast transmissions).

The code1435may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code1435may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some implementations, the code1435may not be directly executable by the processor1440but may cause a computer (for example, when compiled and executed) to perform functions described herein.

FIG.15shows a flowchart illustrating a method1500that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method1500may be implemented by a UE115or its components. For example, the operations of method1500may be performed by a communications manager as described with reference toFIGS.7-10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally, or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At1505, the UE may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. The operations of1505may be performed according to the methods described herein. In some examples, aspects of the operations of1505may be performed by a configuration receiver as described with reference toFIGS.7-10.

At1510, the UE may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. The operations of1510may be performed according to the methods described herein. In some examples, aspects of the operations of1510may be performed by a multicast monitor as described with reference toFIGS.7-10.

At1515, the UE may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The operations of1515may be performed according to the methods described herein. In some examples, aspects of the operations of1515may be performed by a feedback transmitter as described with reference toFIGS.7-10.

FIG.16shows a flowchart illustrating a method1600that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method1600may be implemented by a UE115or its components. For example, the operations of method1600may be performed by a communications manager as described with reference toFIGS.7-10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally, or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At1605, the UE may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. The operations of1605may be performed according to the methods described herein. In some examples, aspects of the operations of1605may be performed by a configuration receiver as described with reference toFIGS.7-10.

At1610, the UE may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. The operations of1610may be performed according to the methods described herein. In some examples, aspects of the operations of1610may be performed by a multicast monitor as described with reference toFIGS.7-10.

At1615, the UE may determine a resource pool available for multicast feedback based on the one or more configurations, in which transmitting the one or more multicast feedback messages includes transmitting the one or more multicast feedback messages using a subset of time-frequency resources of the resource pool. The operations of1615may be performed according to the methods described herein. In some examples, aspects of the operations of1615may be performed by a resource manager as described with reference toFIGS.7-10.

At1620, the UE may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The operations of1620may be performed according to the methods described herein. In some examples, aspects of the operations of1620may be performed by a feedback transmitter as described with reference toFIGS.7-10.

FIG.17shows a flowchart illustrating a method1700that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method1700may be implemented by a UE115or its components. For example, the operations of method1700may be performed by a communications manager as described with reference toFIGS.7-10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally, or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At1705, the UE may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. The operations of1705may be performed according to the methods described herein. In some examples, aspects of the operations of1705may be performed by a configuration receiver as described with reference toFIGS.7-10.

At1710, the UE may receive a timing advance command from the base station, the timing advance command indicating a timing advance for use by the UE while in the inactive mode or the idle mode, in which the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE. The operations of1710may be performed according to the methods described herein. In some examples, aspects of the operations of1710may be performed by a TA receiver as described with reference toFIGS.7-10.

At1715, the UE may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. The operations of1715may be performed according to the methods described herein. In some examples, aspects of the operations of1715may be performed by a multicast monitor as described with reference toFIGS.7-10.

At1720, the UE may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The operations of1720may be performed according to the methods described herein. In some examples, aspects of the operations of1720may be performed by a feedback transmitter as described with reference toFIGS.7-10.

FIG.18shows a flowchart illustrating a method1800that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method1800may be implemented by a UE115or its components. For example, the operations of method1800may be performed by a communications manager as described with reference toFIGS.7-10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally, or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At1805, the UE may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. The operations of1805may be performed according to the methods described herein. In some examples, aspects of the operations of1805may be performed by a configuration receiver as described with reference toFIGS.7-10.

At1810, the UE may receive a timing advance command from the base station, the timing advance command indicating a timing advance for use by the UE while in the inactive mode or the idle mode, in which the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE. The operations of1810may be performed according to the methods described herein. In some examples, aspects of the operations of1810may be performed by a TA receiver as described with reference toFIGS.7-10.

At1815, the UE may receive a second timing advance command from the base station, the second timing advance command indicating a second timing advance for use by the UE while in the inactive mode or the idle mode, in which the second timing advance command corresponds to second set of values for one or more channel metrics associated with the UE and associated with one or more cells including the serving cell for the UE. The operations of1815may be performed according to the methods described herein. In some examples, aspects of the operations of1815may be performed by a TA receiver as described with reference toFIGS.7-10.

At1820, the UE may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. The operations of1820may be performed according to the methods described herein. In some examples, aspects of the operations of1820may be performed by a multicast monitor as described with reference toFIGS.7-10.

At1825, the UE may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The operations of1825may be performed according to the methods described herein. In some examples, aspects of the operations of1825may be performed by a feedback transmitter as described with reference toFIGS.7-10.

FIG.19shows a flowchart illustrating a method1900that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method1900may be implemented by a UE115or its components. For example, the operations of method1900may be performed by a communications manager as described with reference toFIGS.7-10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally, or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At1905, the UE may receive, from a base station, one or more configurations for use by the UE, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station. The operations of1905may be performed according to the methods described herein. In some examples, aspects of the operations of1905may be performed by a configuration receiver as described with reference toFIGS.7-10.

At1910, the UE may determine a set of uplink resources available for a reception status report associated with multicast transmissions from the base station. The operations of1910may be performed according to the methods described herein. In some examples, aspects of the operations of1910may be performed by a resource manager as described with reference toFIGS.7-10.

At1915, the UE may monitor, by the UE while in the inactive mode or the idle mode, a set of time-frequency resources configured for multicast transmissions from the base station. The operations of1915may be performed according to the methods described herein. In some examples, aspects of the operations of1915may be performed by a multicast monitor as described with reference toFIGS.7-10.

At1920, the UE may transmit, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based on the monitoring. The operations of1920may be performed according to the methods described herein. In some examples, aspects of the operations of1920may be performed by a feedback transmitter as described with reference toFIGS.7-10.

At1925, the UE may transmit the reception status report using the set of uplink resources. The operations of1925may be performed according to the methods described herein. In some examples, aspects of the operations of1925may be performed by a status report transmitter as described with reference toFIGS.7-10.

FIG.20shows a flowchart illustrating a method2000that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method2000may be implemented by a base station105or its components. For example, the operations of method2000may be performed by a communications manager as described with reference toFIGS.11-14. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally, or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At2005, the base station may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode. The operations of2005may be performed according to the methods described herein. In some examples, aspects of the operations of2005may be performed by a configuration transmitter as described with reference toFIGS.11-14.

At2010, the base station may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications. The operations of2010may be performed according to the methods described herein. In some examples, aspects of the operations of2010may be performed by a multicast transmitter as described with reference toFIGS.11-14.

At2015, the base station may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations. The operations of2015may be performed according to the methods described herein. In some examples, aspects of the operations of2015may be performed by a feedback monitor as described with reference toFIGS.11-14.

At2105, the base station may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode. The operations of2105may be performed according to the methods described herein. In some examples, aspects of the operations of2105may be performed by a configuration transmitter as described with reference toFIGS.11-14.

At2110, the base station may transmit an indication of a set of RACH resources available for multicast feedback in the one or more configurations. The operations of2110may be performed according to the methods described herein. In some examples, aspects of the operations of2110may be performed by a resource transmitter as described with reference toFIGS.11-14.

At2115, the base station may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications. The operations of2115may be performed according to the methods described herein. In some examples, aspects of the operations of2115may be performed by a multicast transmitter as described with reference toFIGS.11-14.

At2120, the base station may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations and the set of RACH resources. The operations of2120may be performed according to the methods described herein. In some examples, aspects of the operations of2120may be performed by a feedback monitor as described with reference toFIGS.11-14.

FIG.22shows a flowchart illustrating a method2200that supports feedback for multicast transmissions in accordance with aspects of the present disclosure. The operations of method2200may be implemented by a base station105or its components. For example, the operations of method2200may be performed by a communications manager as described with reference toFIGS.11-14. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally, or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At2205, the base station may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode. The operations of2205may be performed according to the methods described herein. In some examples, aspects of the operations of2205may be performed by a configuration transmitter as described with reference toFIGS.11-14.

At2210, the base station may transmit an indication of a set of RACH preambles available for multicast feedback in the one or more configurations. The operations of2210may be performed according to the methods described herein. In some examples, aspects of the operations of2210may be performed by a resource transmitter as described with reference toFIGS.11-14.

At2215, the base station may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications. The operations of2215may be performed according to the methods described herein. In some examples, aspects of the operations of2215may be performed by a multicast transmitter as described with reference toFIGS.11-14.

At2220, the base station may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations and the set of RACH preambles. The operations of2220may be performed according to the methods described herein. In some examples, aspects of the operations of2220may be performed by a feedback monitor as described with reference toFIGS.11-14.

At2305, the base station may transmit, to a UE, one or more configurations for multicast feedback by the UE in an inactive mode or an idle mode. The operations of2305may be performed according to the methods described herein. In some examples, aspects of the operations of2305may be performed by a configuration transmitter as described with reference toFIGS.11-14.

At2310, the base station may transmit an indication of a set of PUCCH resources available for multicast feedback in the one or more configurations. The operations of2310may be performed according to the methods described herein. In some examples, aspects of the operations of2310may be performed by a resource transmitter as described with reference toFIGS.11-14.

At2315, the base station may transmit one or more multicast transmissions via a set of time-frequency resources configured for multicast communications. The operations of2315may be performed according to the methods described herein. In some examples, aspects of the operations of2315may be performed by a multicast transmitter as described with reference toFIGS.11-14.

At2320, the base station may monitor, based on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations and the set of PUCCH resources. The operations of2320may be performed according to the methods described herein. In some examples, aspects of the operations of2320may be performed by a feedback monitor as described with reference toFIGS.11-14.

Aspect 1: A method for wireless communications at a UE, comprising: receiving, from a base station, one or more configurations for the UE to use, while in an inactive mode or an idle mode, to provide feedback associated with multicast transmissions from the base station; monitoring, by the UE while in the inactive mode or the idle mode, a set of time frequency resources configured for multicast transmissions from the base station; and transmitting, by the UE while in the inactive mode or the idle mode, one or more multicast feedback messages in accordance with the one or more configurations based at least in part on the monitoring.

Aspect 2: The method of aspect 1, further comprising determining a set of random access channel resources available for multicast feedback based at least in part on a resource allocation indicated by the one or more configurations, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages via the set of random access channel resources.

Aspect 3: The method of any of aspects 1 through 2, further comprising: determining a set of random access channel preambles available for multicast feedback based at least in part on a resource allocation indicated by the one or more configurations; and selecting a preamble of the set of random access channel preambles, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using the selected preamble.

Aspect 4: The method of any of aspects 1 through 3, further comprising receiving a multicast message over the set of time frequency resources based at least in part on the monitoring, wherein selecting the preamble of the set of random access channel preambles comprises selecting the preamble based at least in part on a channel quality metric associated with the received multicast message.

Aspect 5: The method of any of aspects 1 through 4, further comprising: receiving a multicast message over the set of time frequency resources based at least in part on the monitoring; transmitting channel quality information associated with the received multicast message, wherein the channel quality information comprises one or more of reference signal received power, beam direction, beam width, geographical location, or altitude and azimuth values associated with one or more beams; and determining time frequency resources for multicast feedback based at least in part on the channel quality information, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages via the determined time frequency resources.

Aspect 6: The method of any of aspects 1 through 5, further comprising determining a resource pool available for multicast feedback based at least in part on the one or more configurations, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using a subset of time frequency resources of the resource pool.

Aspect 7: The method of any of aspects 1 through 6, further comprising determining a set of physical uplink control channel resources available for multicast feedback based at least in part on the one or more configurations, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using a subset of the physical uplink control channel resources.

Aspect 8: The method of aspect 7, further comprising: determining an uplink control format for the one or more multicast feedback messages; and padding a payload of the one or more multicast feedback messages based at least in part on a size associated with the uplink control format.

Aspect 9: The method of any of aspects 1 through 8, further comprising receiving a timing advance command from the base station, the timing advance command indicating a timing advance for the UE to use while in the inactive mode or the idle mode, wherein the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE.

Aspect 10: The method of aspect 9, further comprising receiving a second timing advance command from the base station, the second timing advance command indicating a second timing advance for the UE to use while in the inactive mode or the idle mode, wherein the second timing advance command corresponds to second set of values for one or more channel metrics associated with the UE and associated with one or more cells including the serving cell for the UE.

Aspect 11: The method of aspect 10, further comprising measuring a set of channel metrics of the one or more cells including the serving cell, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using the timing advance based at least in part on the set of channel metrics satisfying the first set of values or using the second timing advance based at least in part on the set of channel metrics satisfying the second set of values.

Aspect 12: The method of any of aspects 10 through 11, wherein the one or more channel metrics comprise one or more of a reference signal received power, a relative delay between the serving cell and one or more other cells, or a positioning range of the UE.

Aspect 13: The method of any of aspects 10 through 12, further comprising receiving one or more of the timing advance command or the second timing advance command in the one or more configurations, the one or more configurations indicating a set of uplink resources for multicast feedback, wherein transmitting the one or more multicast feedback messages comprises transmitting the one or more multicast feedback messages using the set of uplink resources.

Aspect 14: The method of any of aspects 9 through 13, further comprising receiving a set of neural network parameters in the timing advance command from the base station, wherein the set of neural network parameters indicate the timing advance.

Aspect 15: The method of any of aspects 1 through 14, further comprising: receiving, at the UE while in a connected mode, a neural network model and a set of neural network parameters from the base station, the neural network model and the set of neural network parameters being associated with a neural network for a timing advance; receiving one or more neural network parameters from the base station; and determining the timing advance based at least in part on the neural network model, the set of neural network parameters, and the one or more neural network parameters, wherein transmitting the one or more multicast feedback messages comprises transmitting, by the UE while in the inactive mode or the idle mode, the one or more multicast feedback messages based at least in part on the timing advance.

Aspect 16: The method of any of aspects 1 through 15, further comprising: determining a set of uplink resources available for a reception status report associated with multicast transmissions from the base station, wherein the set of uplink resources comprises random access channel resources or uplink control channel resources; and transmitting the reception status report using the set of uplink resources.

Aspect 17: The method of aspect 16, further comprising: monitoring multiple time occasions for multicast transmissions from the base station; receiving a plurality of physical control channels for multicast transmissions based at least in part on the monitoring of the multiple time occasions; transmitting an indication of a quantity of the received plurality of physical control channels for multicast transmissions in the reception status report; and transmitting, in the reception status report, a ratio between the quantity of the received plurality of physical control channels for multicast transmissions and a total quantity of physical control channels for multicast transmissions scheduled over the multiple time occasions, wherein the total quantity of physical control channels for multicast transmissions corresponds to a set of uplink control channel resources.

Aspect 18: The method of any of aspects 1 through 17, further comprising: receiving a broadcast message from the base station indicating a counting duration for a service of the multicast transmissions supported by the base station; and transmitting a service request message over the counting duration requesting the service of the multicast transmissions supported by the base station based at least in part on an identifier of the UE.

Aspect 19: The method of aspect 18, further comprising receiving, from the base station, a probability indicator for the UE, wherein transmitting the service request message comprises transmitting the message in accordance with the probability indicator.

Aspect 20: A method for wireless communications at a base station, comprising: transmitting, to a UE, one or more configurations for multicast feedback for use by the UE while in an inactive mode or an idle mode; transmitting one or more multicast transmissions via a set of time frequency resources configured for multicast communications; and monitoring, based at least in part on transmitting the one or more multicast transmissions, for one or more multicast feedback messages from the UE in accordance with the one or more configurations.

Aspect 21: The method of aspect 20, further comprising: transmitting an indication of a set of random access channel resources available for multicast feedback in the one or more configurations; and monitoring the set of random access channel resources for the one or more multicast feedback messages.

Aspect 22: The method of any of aspects 20 through 21, further comprising: transmitting an indication of a set of random access channel preambles available for multicast feedback in the one or more configurations; and monitoring for the one or more multicast feedback messages based at least in part on the set of random access channel preambles.

Aspect 23: The method of any of aspects 20 through 22, further comprising: receiving, from the UE, channel quality information associated with a multicast channel used for multicast communications with the UE, wherein the channel quality information comprises one or more of reference signal received power, beam direction, beam width, geographical location, or altitude and azimuth values associated with one or more beams; determining a resource pool for multicast feedback for the UE based at least in part on the channel quality information; and transmitting an indication of the resource pool in the one or more configurations.

Aspect 24: The method of aspect 23, further comprising receiving the one or more multicast feedback messages via a subset of time frequency resources of the resource pool based at least in part on the monitoring.

Aspect 25: The method of any of aspects 20 through 24, further comprising: transmitting an indication of a set of physical uplink control channel resources available for multicast feedback in the one or more configurations; and monitoring the set of physical uplink control channel resources for the one or more multicast feedback messages.

Aspect 26: The method of any of aspects 20 through 25, further comprising transmitting a timing advance command to the UE, the timing advance command indicating a timing advance for the UE to use while in the inactive mode or the idle mode, wherein the timing advance command corresponds to first set of values for one or more channel metrics associated with the UE and associated with one or more cells including a serving cell for the UE.

Aspect 27: The method of aspect 26, further comprising transmitting a second timing advance command to the UE, the second timing advance command indicating a second timing advance for the UE to use while in the inactive mode or the idle mode, wherein the second timing advance command corresponds to second set of values for one or more channel metrics associated with the UE and associated with one or more cells including the serving cell for the UE.

Aspect 28: The method of aspect 27, further comprising receiving, based at least in part on the monitoring, the one or more multicast feedback messages according to the timing advance based at least in part on a set of channel metrics at the UE satisfying the first set of values or according to the second timing advance based at least in part on a set of channel metrics at the UE satisfying the second set of values.

Aspect 33: An apparatus for wireless communications at a base station, comprising at least one means for performing a method of any of aspects 20 through 28.