Patent Description:
Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for sidelink channel state information reporting.

Wireless communication systems, as are for example described in 3GPP R1-<NUM>, 3GPP R1-<NUM>, and <CIT>, are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts.

In some aspects, a method of wireless communication, performed by a target user equipment (UE), includes receiving a channel state information (CSI) reference signal (RS) from a source UE via a sidelink communication; determining that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers; and transmitting a CSI report in a media access control (MAC) control element (CE) as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, wherein the transmission of the sidelink CSI report is prioritized above a sidelink transport channel.

In some aspects, an apparatus for wireless communication includes means for receiving a CSI RS from a source UE via a sidelink communication; means for determining that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers; and means for transmitting a CSI report in a MAC CE as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, wherein the transmission of the sidelink CSI report is prioritized above a sidelink transport channel.

In some aspects, the CSI report includes information identifying at least one of a hybrid automatic repeat request process identifier for the CSI RS, a channel quality indicator, a rank indicator, or a slot number on which the CSI RS was received.

In some aspects, the method includes identifying a sidelink grant for transmission of the MAC CE, wherein the sidelink grant includes resources for the CSI report and a corresponding subheader, and transmitting the CSI report includes transmitting the CSI report via the sidelink grant for transmission of the MAC CE in accordance with a logical channel prioritization.

In some aspects, the method includes activating a sidelink CSI report timer in connection with the lower-layer determined source identifier based at least in part on the transmission of the CSI report.

In some aspects, the transmission of the CSI report includes transmitting the CSI report based at least in part on a logical channel prioritization.

In some aspects, the method includes requesting a grant for transmitting the CSI report; receiving the grant for transmitting the CSI report based at least in part on requesting the grant, wherein the grant includes resources for transmitting the MAC CE and a corresponding MAC subheader; and transmitting the CSI report using the grant.

In some aspects, a transmission of the CSI report using the grant includes padding bits to fill the grant.

In some aspects, the method includes determining a transmission window for transmitting the CSI report; and processing the CSI report in accordance with the transmission window.

Aspects generally include a method, apparatus, computer program product, as substantially described herein with reference to and as illustrated by the accompanying drawings and specification.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with sidelink channel state information (CSI) reporting, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors of the base station <NUM> and/or the UE <NUM>, may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein.

In some aspects, UE <NUM> may include means for receiving a CSI reference signal (RS) from a source UE via a sidelink communication, means for determining that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, means for transmitting a CSI report in a media access control (MAC) control element (CE) as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

In some communication systems, a UE may receive a CSI RS from a BS and may perform a measurement of the CSI RS to determine a network characteristic. Based at least in part on performing the measurement of the CSI RS, the UE may provide a CSI report as a response to the CSI RS. The CSI report may include information regarding the network characteristic, such as a channel quality indicator (CQI), a rank indicator (RI), and/or the like.

However, in other communication systems, such as device-to-device communication systems (e.g., V2X, V2V, and/or the like), the UE may receive the CSI RS from other UEs rather than (or in addition to) from a BS. In this case, a UE that transmits the CSI RS may be termed a source UE, and a UE that receives the CSI RS may be termed a target UE. However, when a source UE transmits a CSI RS, many target UEs may detect the CSI RS. If every target UE that detects the CSI RS attempts to provide a CSI report, excessive network traffic may result. Similarly, a single target UE may receive CSI RSs from many source UEs, which may result in excessive utilization of processing resources to respond to the CSI RSs. Furthermore, when many UEs are transmitting and receiving CSI reports, some CSI reports may be duplicative of other CSI reports, thereby resulting in inefficient utilization of network resources.

Some aspects described herein enable sidelink CSI reporting. For example, a target UE may determine, at an upper layer (e.g., a MAC layer, a radio resource control (RRC) layer, and/or the like), a set of source UEs for which to provide CSI reporting when a CSI RS is received and may, at a lower layer (e.g., a physical layer), detect receipt of a CSI RS from a source UE and determine that the source UE is included in the set of source UEs for which the target UE to provide CSI reporting. In this case, based at least in part on the source UE being included in the set of source UEs for which the target UE is to perform CSI reporting, the target UE may generate and transmit a CSI report to the source UE. In this way, the source UE and the target UE enable sidelink CSI reporting without excessive network traffic and/or inefficient utilization of network resources.

<FIG> is a diagram illustrating an example <NUM> of sidelink channel state information reporting, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> includes a source UE <NUM> and a target UE <NUM>.

As further shown in <FIG>, and by reference number <NUM>, target UE <NUM> may receive a CSI RS. For example, target UE <NUM> may receive the CSI RS from a source UE <NUM>. In some aspects, target UE <NUM> may receive CSI RSs from a plurality of source UEs <NUM>. For example, when operating in a V2X deployment, a V2V deployment, and/or the like, a plurality of UEs <NUM> (e.g., source UEs <NUM>) may transmit CSI RSs to enable measurements of channel conditions, and target UE <NUM> may receive one or more of the CSI RSs. In some aspects, target UE <NUM> may perform a measurement of the CSI RS and may determine a characteristic of a channel based at least in part on the measurement. For example, target UE <NUM> may determine a CQI value, an RI value, and/or the like.

As further shown in <FIG>, and by reference number <NUM>, target UE <NUM> may determine, at an upper layer, whether target UE <NUM> is configured to perform sidelink CSI reporting. Additionally, or alternatively, target UE <NUM> may determine, at the upper layer, a list of identifiers of source UEs <NUM> for which target UE <NUM> is to perform CSI reporting. For example, when target UE <NUM> is configured, at an upper layer, to perform sidelink CSI reporting, target UE <NUM> may determine a list of identifiers of source UEs <NUM> for which target UE <NUM> is to perform CSI reporting. In some aspects, the list of identifiers may correspond to all source UEs <NUM> within a threshold proximity of target UE <NUM>. In some aspects, the list of identifiers may be a subset of source UEs <NUM> within the threshold proximity of target UE <NUM>.

As further shown in <FIG>, and by reference number <NUM>, target UE <NUM> may determine, at a lower layer, whether an identifier of source UE <NUM> is included in the list of identifiers of source UEs <NUM> for which target UE <NUM> is to perform CSI reporting. For example, at a lower layer, target UE <NUM> may detect reception of the CSI RS and may determine, based at least in part on information included in the CSI RS identifying source UE <NUM>, whether an identifier of source UE <NUM> is included in the upper layer-determined list of source UEs <NUM> for which target UE <NUM> is to perform CSI reporting. In this case, when an identifier of source UE <NUM> is not included in the list of identifiers, target UE <NUM> may determine to forgo transmitting a CSI report as a response to the CSI RS. Additionally, or alternatively, when an identifier of source UE <NUM> is included in the list of identifiers, target UE <NUM> may determine to transmit the CSI report as a response to the CSI RS.

As further shown in <FIG>, and by reference number <NUM>, target UE <NUM> may transmit a CSI report in a MAC CE using an existing sidelink grant or after requesting a sidelink grant. For example, when a medium access control (MAC) entity of target UE <NUM> has a sidelink grant for transmission, the MAC entity of target UE <NUM> may determine whether allocated resources of the sidelink grant are sufficient to accommodate a MAC control element (CE) to convey a CSI report, a corresponding subheader, and/or the like. In this case, if the allocated resources are sufficient, target UE <NUM> may cause a multiplexing and assembly procedure to generate a MAC CE based at least in part on a measurement of the CSI RS performed at a physical layer, and may transmit a CSI report in the MAC CE to source UE <NUM> to enable source UE <NUM> to control one or more transmission parameters. In some aspects, target UE <NUM> may include padding bits to fill the grant (e.g., when the grant is larger than the CSI RS and corresponding subheader).

Additionally, or alternatively, when the sidelink grant is not sufficient or when the MAC entity determines that there is not an existing sidelink grant for transmission, the MAC entity of target UE <NUM> may transmit a request for a sidelink grant and may receive a response identifying a sidelink grant with allocated resources for transmitting the CSI report on a sidelink. In some aspects, target UE <NUM> may include an indicator of a measurement or a channel condition in the CSI report. For example, target UE <NUM> may include information identifying a CQI, an RI, and/or the like. Additionally, or alternatively, target UE <NUM> may include information identifying a hybrid automatic repeat request (HARQ) process identifier, a slot number on which the CSI RS was received, and/or the like.

In some aspects, target UE <NUM> may determine whether to transmit the CSI report using a sidelink grant based at least in part on a prioritization. For example, target UE <NUM> may prioritize a set of logical channels, such that a sidelink CSI report MAC CE is prioritized over a sidelink control channel and/or a sidelink transport channel. In some aspects, target UE <NUM> may process the CSI report in accordance with a transmission timeline requirement. For example, target UE <NUM> may determine an amount of time before an end of an upper layer-configured time window in which the CSI RS is received. In this case, target UE <NUM> may indicate the upper layer-configured time window to lower layers in order to enable prioritization of processing and transmission of the CSI RS report. In this way, target UE <NUM> enables prioritization of use of a limited set of allocated resources, such that source UE <NUM> may perform transmission control.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a target UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the target UE (e.g., UE <NUM> and/or the like) performs operations associated with sidelink channel state information reporting.

As shown in <FIG>, in some aspects, process <NUM> may include receiving a CSI RS from a source UE via a sidelink communication (block <NUM>). For example, the target UE (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) may receive a CSI RS from a source UE via a sidelink communication, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include determining that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers (block <NUM>). For example, the target UE (e.g., using controller/processor <NUM> and/or the like) may determine that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting a CSI report in a MAC CE as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers (block <NUM>). For example, the target UE (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) may transmit a CSI report in a MAC CE as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers, as described above.

In a first aspect, the CSI report includes information identifying at least one of a hybrid automatic repeat request process identifier for the CSI RS, a channel quality indicator, a rank indicator, or a slot number on which the CSI RS was received.

In a second aspect, alone or in combination with the first aspect, process <NUM> includes identifying a sidelink grant for transmission of the MAC CE, wherein the sidelink grant includes resources for the CSI report and a corresponding subheader, and transmitting the CSI report includes transmitting the CSI report via the sidelink grant for transmission of the MAC CE in accordance with a logical channel prioritization.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes activating a sidelink CSI report timer in connection with the lower-layer determined source identifier based at least in part on the transmission of the CSI report.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the transmission of the CSI report includes transmitting the CSI report based at least in part on a logical channel prioritization.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the logical channel prioritization includes the CSI report being prioritized above a sidelink control channel and a corresponding sidelink transport channel.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, process <NUM> includes requesting a grant for transmitting the CSI report; receiving the grant for transmitting the CSI report based at least in part on requesting the grant, wherein the grant includes resources for transmitting the MAC CE and a corresponding MAC subheader; and transmitting the CSI report using the grant.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, a transmission of the CSI report using the grant includes padding bits to fill the grant.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process <NUM> includes determining a transmission window for transmitting the CSI report; and processing the CSI report in accordance with the transmission window.

<FIG> is a conceptual data flow diagram <NUM> illustrating data flow between different modules/means/components in an example apparatus <NUM>. The apparatus <NUM> may be a target UE (e.g., UE <NUM>). In some aspects, the apparatus <NUM> includes a reception component <NUM>, a determination component <NUM>, an identification component <NUM>, an activation component <NUM>, a grant request component <NUM>, a report processor component, <NUM>, and/or a transmission component <NUM>.

The reception component <NUM> may receive, from the UE <NUM> (e.g., a source UE) and as data <NUM>, information associated with a CSI RS. For example, the reception component <NUM> may receive a CSI RS from the UE <NUM> and may perform a measurement to enable the apparatus <NUM> to provide a sidelink CSI report as a response.

The determination component <NUM> may receive, from the reception component <NUM>, and as data <NUM>, information associated with determining whether to perform CSI reporting as a response to the CSI RS. For example, the determination component <NUM> may receive information indicating an identifier of the UE <NUM>. In this case, the determination component <NUM> may determine whether the identifier of the UE <NUM> is included in a list of identifiers of source UEs for which the apparatus is to perform CSI reporting. In this case, the determination component may provide, to the transmission component <NUM>, and as data <NUM>, information identifying a CSI report for transmission. The transmission component <NUM> may provide, to the UE <NUM> and as data <NUM>, the CSI report.

In some aspects, based at least in part on determining to perform CSI reporting, the determination component <NUM> may provide, to the identification component <NUM>, and as data <NUM>, data associated with identifying a sidelink grant for transmission of a MAC CE to convey the CSI report. In this case, the identification component <NUM> may identify a sidelink grant, and may provide, to the transmission component <NUM> and as data <NUM>, information indicating the grant to use for transmission of the MAC CE to convey the CSI report. In some aspects, based at least in part on the transmission component <NUM> transmitting the CSI report, the transmission component <NUM> may provide, to activation component <NUM> and as data <NUM>, an indication of the transmission of the CSI report, which may cause the activation component <NUM> to activate a sidelink CSI report timer for the UE <NUM>.

In some aspects, the determination component <NUM> may provide, to grant request component <NUM>, and as data <NUM>, information indicating that the apparatus <NUM> is to perform CSI reporting. In this case, the grant request component <NUM> may cause, using data <NUM>, transmission component <NUM> to request a grant. Based at least in part on requesting the grant, the reception component <NUM> may receive an indication of the grant and may cause the transmission component <NUM> to transmit a MAC CE to convey the CSI report using the grant. In some aspects, the determination component <NUM> may determine a timeline for processing the CSI report, and may provide, to report processor component <NUM>, and as data <NUM>, information identifying the timeline. In this case, report processor component <NUM> may process the CSI RS to generate the CSI report in accordance with the CSI report.

The apparatus <NUM> may include additional components that perform each of the blocks of the algorithm in the aforementioned process <NUM> of <FIG> and/or the like. Each block in the aforementioned process <NUM> of <FIG> and/or the like may be performed by a component and the apparatus may include one or more of those components.

Aspect <NUM>: A method of wireless communication performed by a target user equipment (UE), comprising: receiving a channel state information (CSI) reference signal (RS) from a source UE via a sidelink communication; determining that a lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers; and transmitting a CSI report in a media access control (MAC) control element (CE) as a response to the CSI RS, based at least in part on the determination that the lower-layer determined source identifier of the source UE is included in a set of upper-layer determined source identifiers.

Aspect <NUM>: The method of aspect <NUM>, wherein the CSI report includes information identifying at least one of: a hybrid automatic repeat request process identifier for the CSI RS, a channel quality indicator, a rank indicator, or a slot number on which the CSI RS was received.

Aspect <NUM>: The method of any of aspects <NUM> to <NUM>, further comprising: identifying a sidelink grant for transmission of the MAC CE, wherein the sidelink grant includes resources for the CSI report and a corresponding subheader; and wherein transmitting the CSI report comprises: transmitting the CSI report via the sidelink grant for transmission of the MAC CE in accordance with a logical channel prioritization.

Aspect <NUM>: The method of aspect <NUM>, further comprising: activating a sidelink CSI report timer in connection with the lower-layer determined source identifier based at least in part on the transmission of the CSI report.

Aspect <NUM>: The method of any of aspects <NUM> to <NUM>, wherein the transmission of the CSI report comprises: transmitting the CSI report based at least in part on a logical channel prioritization.

Aspect <NUM>: The method of aspect <NUM>, wherein the logical channel prioritization includes the CSI report being prioritized above a sidelink transport channel.

Aspect <NUM>: The method of any of aspects <NUM> to <NUM>, further comprising: requesting a grant for transmitting the CSI report; receiving the grant for transmitting the CSI report based at least in part on requesting the grant, wherein the grant includes resources for transmitting the MAC CE and a corresponding MAC subheader; and transmitting the CSI report using the grant.

Aspect <NUM>: The method of aspect <NUM>, wherein a transmission of the CSI report using the grant includes padding bits to fill the grant.

Aspect <NUM>: The method of any of aspects <NUM> to <NUM>, further comprising: determining a transmission window for transmitting the CSI report; and processing the CSI report in accordance with the transmission window.

However, the protection scope of this application shall be subject to the protection scope of the claims.

Claim 1:
A method of wireless communication performed by a target user equipment, UE (<NUM>), comprising:
receiving (<NUM>) a channel state information, CSI, reference signal, RS, from a source UE (<NUM>) via a sidelink communication;
determining (<NUM>) that a lower-layer source identifier of the source UE (<NUM>) is included in a set of upper-layer source identifiers; and
transmitting (<NUM>) a sidelink CSI report in a media access control, MAC, control element, CE, as a response to the CSI RS, based at least in part on the determination that the lower-layer source identifier of the source UE (<NUM>) is included in a set of upper-layer source identifiers,
wherein the transmission of the sidelink CSI report is prioritized above a sidelink transport channel.