Device for Power Control of Sidelink Feedback

Abstract

The present invention relates to devices in a mobile network that communicate via a sidelink (SL). Specifically, the present invention relates to power control of SL feedback, i.e., physical SL feedback channel (PSFCH) power control. To this end, the present invention proposes a first user equipment (UE) for performing the power control and a second UE for supporting the power control. The first UE is configured to select communication resources for sending a feedback message to the second UE on the SL, and to select a power level for sending the feedback message, wherein the power level is selected based on the communication resources. The second UE is configured to provide a configuration message to the first UE, wherein the configuration message indicates at least one association between communication resources and power control configurations.

Description

Technical Field

[0001] The present invention relates to devices in a mobile network that communicate via a sidelink (SL), and more particularly to a user equipment (UE). The mobile network may include a fifth-generation (5G) mobile or cellular communication system (5G system, 5GS) or network. Specifically, the present invention relates to power control of SL feedback, i.e., physical SL feedback channel (PSFCH) power control, for example, for new radio (NR) vehicle-to-anything (V2X). To this end, the present invention proposes a first UE for performing power control, provides a second UE for supporting power control, and provides a corresponding method. th SL feedback is feedback on unicast or multicast transmissions in the SL (between UEs). Unicast transmission is a transmission from a transmit UE (Tx UE) to a receive UE (Rx UE), and multicast transmission is a transmission from a Tx UE to a group of Rx UEs. In the present invention, the Tx UE is referred to as the source UE (or also referred to as the "second UE"), and the Rx UE is referred to as the target UE (or also referred to as the "first UE"). For SL feedback on unicast or multicast transmissions, the roles of the UEs are reversed: i.e., the target UE becomes the sender of the SL feedback, and the source UE becomes the receiver of the SL feedback, as Background Art

[0002] SL feedback is feedback on unicast or multicast transmissions in the SL (between UEs). Unicast transmission is a transmission from a transmit UE (Tx UE) to a receive UE (Rx UE), and multicast transmission is a transmission from a Tx UE to a group of Rx UEs. In the present invention, the Tx UE is referred to as the source UE (or also referred to as the "second UE"), and the Rx UE is referred to as the target UE (or also referred to as the "first UE"). For SL feedback on unicast or multicast transmissions, the roles of the UEs are reversed: i.e., the target UE becomes the sender of the SL feedback, and the source UE becomes the receiver of the SL feedback, as Figure 1 shown.

[0003] For unicast and multicast transmissions, feedback from one or more target UEs to the source UE can be performed for various purposes, for example, including:

[0004] · Hybrid automatic repeat request (HARQ) feedback: One or more target UEs can send a negative acknowledgement (NACK) and / or can send an acknowledgement (ACK) to the source UE.

[0005] · Feedback on power control of the physical sidelink control channel (PSCCH) and / or the physical sidelink shared channel (PSSCH): One or more target UEs may send the SL reference signal received power (SL-RSRP) to the source UE, or may send information about the SL-RSRP to the source UE for SL path loss derivation at the source UE (e.g., SL-RSRP report). The SL-RSRP may also be referred to as the RSRP.

[0006] · Feedback on channel state information (CSI) reporting for SL transmission: One or more target UEs may send a CSI report including a channel quality indicator (CQI), a rank indicator (RI), or a precoding matrix indicator (PMI) to the source UE.

[0007] The SL feedback, SL feedback link, or SL feedback channel may also be referred to as the PSFCH. Summary of the Invention

[0008] Embodiments of the present invention are also based on the following considerations made by the inventors.

[0009] Similar to the PSCCH / PSSCH power control performed at the source UE, when the target UE is within the network coverage area (i.e., the gNB is the serving gNB of the target UE), the PSFCH power control at the target UE may be based on the downlink (DL) path loss (Uu path loss) from the gNB (usually from the "network" or "base station") to the target UE. Additionally or alternatively, the PSFCH power control may be based on the SL path loss between the source UE and the target UE. In the present invention, unless otherwise specified, the DL path loss is referred to as the path loss from the gNB to the target UE, and the SL path loss is referred to as the path loss between the source UE and the target UE.

[0010] The PSFCH power control may consider the DL path loss to mitigate any interference to the gNB. Considering the SL path loss for the PSFCH power control may prevent the target UE from transmitting at a power higher than necessary. For example, in the case where the SL path loss is much smaller than the DL path loss, as Figure 2 exemplarily shown for unicast.

[0011] In addition, when the target UEs for multicast transmission have different SL path losses, taking into account the SL path loss can result in the same (or at least similar) received power at the source UE (i.e., the UE receiving the feedback) for several target UEs, e.g., for multicast feedback, thereby alleviating the near-far problem and the impact of in-band emissions. This is exemplarily shown in Figure 3 When the target UEs send feedback using code division multiplexing (CDM) and frequency division multiplexing (FDM), respectively, it may cause the near-far problem and in-band emissions.

[0012] However, to implement PSFCH power control based on the SL path loss, the target UE needs to determine the SL path loss from the target UE to the source UE. To enable each target UE to obtain the SL path loss to the source UE, additional signaling will be required, e.g., to enable the source UE to indicate the transmission power used by the source UE to send the reference signal, or to indicate the SL path loss to each target UE derived at the source UE. This will come at the cost of overhead or may not always be feasible.

[0013] Therefore, Rel.16 NR V2X proposes that the PFSCH power control at the target UE (when the target UE is within coverage) can be based on the DL path loss from the gNB to the target UE, but should not be based on the SL path loss between the source UE and the target UE. Thus, disadvantageously, this PFSCH power control does not have the benefits that arise when considering the SL path loss. That is, one or more target UEs may transmit at a power higher than necessary.

[0014] In view of this, embodiments of the present invention aim to provide an improved SL feedback power control (PFSCH power control). The goal is to provide a more energy-efficient SL feedback power control. Therefore, the source UE should be able to determine a specific SL feedback power control for one or more target UEs. In addition, for the SL feedback power control, it should be possible to consider additional feedback characteristics and / or parameters, e.g., including the SL path loss.

[0015] The above object is achieved by embodiments of the present invention described in the appended independent claims. Advantageous implementations of embodiments of the present invention are further defined in the dependent claims.

[0016] A first aspect of the present invention provides a first UE for performing power control of SL feedback, the first UE being configured to: select communication resources for sending a feedback message to a second UE over SL; and select a power level for sending the feedback message, wherein the power level is selected based on the communication resources.

[0017] Therefore, the first UE can configure the PSFCH power control according to the communication resource for the first UE to send the feedback message (i.e., the power control for the feedback in SL of the first UE). Therefore, the PSFCH power control can be configured for each communication resource or PSFCH, where one or more communication resources or feedback channels (PSFCH) can be configured for feedback.

[0018] The first UE can provide a more energy-efficient SL feedback power control. Specifically, it can be avoided that the first UE uses too much power during feedback. The first UE can be configured by the second UE, that is, the second UE can be able to determine the SL feedback power control for the first UE based on the communication resource used by the first UE for feedback. In addition, the SL feedback power control at the first UE can consider additional feedback features and / or parameters for power control, for example, the SL path loss or interference associated with the communication resource.

[0019] The communication resource can also be referred to as a "feedback resource" or a "PSFCH resource" or a "PSFCH communication resource", and can include time resources and / or frequency resources and / or code resources and / or spatial resources selected or configured for sending the SL feedback (message). The first UE is also referred to as the "target UE". The second UE is also referred to as the "source UE".

[0020] In one implementation of the first aspect, the first UE is used to: also select the power level based on the type and / or content of the feedback message.

[0021] Therefore, for example, since certain types and / or content of the feedback message can use less or more power, even more energy-efficient power control is achieved.

[0022] In one implementation of the first aspect, the type of the feedback message includes at least one of the following: HARQ feedback; RSRP report; CSI report.

[0023] In one implementation of the first aspect, the content of the feedback message includes at least one of the following: ACK feedback; NACK feedback; NACK-only feedback; feedback of PSCCH; feedback of PSSCH.

[0024] The feedback of PSCCH and / or PSSCH can specifically be the feedback of PSCCH / PSSCH power control.

[0025] In one implementation of the first aspect, the first UE is further configured to: further select the power level based on one or more path losses, where the one or more path losses include at least one of the following: the SL path loss between the first UE and the second UE; the DL path loss between the first UE and the base station serving the first UE; the path loss between the first UE and a third UE; the path loss between the first UE and another base station.

[0026] Therefore, high-energy-efficiency power control of feedback is achieved while ensuring the reliability of feedback and / or minimizing interference to other devices or links.

[0027] The base station may refer to network equipment, evolved NodeB (eNB), NodeB, next generation NodeB (gNB), master eNB (MeNB), secondary eNB (SeNB), remote radio head, access point, transmit-receive point (TRP), etc.

[0028] In one implementation of the first aspect, the first UE is further configured to: further determine the power level based on whether the feedback message is for unicast feedback or for multicast feedback.

[0029] In one implementation of the first aspect, the first UE is further configured to: select the communication resource from a resource set.

[0030] The resource set may be pre-configured, may be configured by the second UE, or may be dynamically adjusted or determined at the first UE, that is, determined based on the resources used for the transmission from the second UE to the first UE. The resource set may be shared by two or more first UEs, but may also be a separate resource set for the first UE.

[0031] In one implementation of the first aspect, the resource set is allocated to the first UE by the second UE or the base station serving the first UE.

[0032] In one implementation of the first aspect, the first UE is further configured to select the communication resource based on at least one of the following: the distance between the first UE and the second UE; the SL path loss between the first UE and the second UE; the RSRP at the first UE; the identifier of the first UE; the identifier of the second UE.

[0033] Therefore, even higher-energy-efficiency feedback power control is achieved.

[0034] In one implementation of the first aspect, the first UE is further configured to: receive a configuration message or a configuration update message, where the configuration message or the configuration update message indicates at least one association between communication resources and power control configuration.

[0035] The power control configuration may refer to a configuration (or specification) on how the first UE selects a power level, and the configuration may be based on one or more path losses and one or more power control parameters. That is, the first UE may select a power level based on the configuration or the updated configuration.

[0036] In one implementation of the first aspect, the first UE is further configured to select the power level based on at least one of the following: a maximum power level; a fixed power level; one or more nominal power levels, each nominal power level being associated with a specific path loss used by the first UE to select the power level; and one or more factors for partial power control, each factor being associated with a specific path loss used by the first UE to select the power level.

[0037] In one implementation of the first aspect, the communication resources include time resources and / or frequency resources and / or space resources and / or code resources.

[0038] A second aspect of the present invention provides a second UE for supporting power control of SL feedback. The second UE is configured to: provide a configuration message to the first UE, where the configuration message indicates at least one association between communication resources and power control configuration.

[0039] In one implementation of the second aspect, the second UE is further configured to: receive a feedback message from the first UE on the communication resources; determine interference to the communication resources at the second UE; and based on the determined interference, provide a configuration update message to the first UE, where the configuration update message indicates at least one updated association between communication resources and power control configuration.

[0040] By sending a configuration message or a configuration update message, the second UE can support power control of SL feedback performed at the first UE. The first UE may select a power level for sending the SL feedback based on the configuration message or the configuration update message, for example, according to the association or the updated association with the selected communication resources.

[0041] In one implementation of the second aspect, the second UE is further configured to: provide the configuration message and / or the configuration update message as a multicast message to a plurality of first UEs.

[0042] A third aspect of the present invention provides a method for performing power control on SL feedback, the method comprising: selecting communication resources for sending a feedback message on SL; and selecting a power level for sending the feedback message, wherein the power level is selected based on the communication resources.

[0043] In one implementation of the third aspect, the method further comprises: selecting the power level further based on the type and / or content of the feedback message.

[0044] In one implementation of the third aspect, the type of the feedback message includes at least one of the following: HARQ feedback; RSRP report; channel state information (CSI) report.

[0045] In one implementation of the third aspect, the content of the feedback message includes at least one of the following: ACK feedback; NACK feedback; NACK-only feedback; feedback of PSCCH; feedback of PSSCH.

[0046] In one implementation of the third aspect, the method further comprises: selecting the power level further based on one or more path losses, wherein the one or more path losses include at least one of the following: SL path loss between a first UE and a second UE; DL path loss between the first UE and a base station serving the first UE; path loss between the first UE and a third UE; path loss between the first UE and another base station.

[0047] The first UE may specifically execute the method of the third aspect.

[0048] In one implementation of the third aspect, the method further comprises: determining the power level further based on whether the feedback message is for unicast feedback or for multicast feedback.

[0049] In one implementation of the third aspect, the method further comprises: selecting the communication resources from a resource set.

[0050] In one implementation of the third aspect, the resource set is allocated by a UE or a base station.

[0051] In one implementation of the third aspect, the method comprises selecting the communication resources based on at least one of the following: distance between a first UE and a second UE; SL path loss between the first UE and the second UE; RSRP at the first UE; identifier of the first UE; identifier of the second UE.

[0052] The first UE may specifically execute the method of the third aspect.

[0053] In one implementation of the third aspect, the method further includes: receiving a configuration message or a configuration update message, where the configuration message or the configuration update message indicates at least one association between communication resources and power control configuration.

[0054] In one implementation of the third aspect, the method further includes selecting the power level based on at least one of the following: a maximum power level; a fixed power level; one or more nominal power levels, each nominal power level being associated with a specific path loss used for selecting the power level; one or more factors for partial power control, each factor being associated with a specific path loss used for selecting the power level.

[0055] In one implementation of the third aspect, the communication resources include time resources and / or frequency resources and / or spatial resources and / or code resources.

[0056] The method of the third aspect and its implementation realizes the same advantages as the device of the first aspect and its corresponding implementation.

[0057] A fourth aspect of the present invention provides a method for supporting power control of SL feedback, the method including: providing a configuration message, where the configuration message indicates at least one association between communication resources and power control configuration.

[0058] In one implementation of the fourth aspect, the method further includes: receiving a feedback message on the communication resources; determining interference to the communication resources; based on the determined interference, providing a configuration update message, where the configuration update message indicates at least one updated association between communication resources and power control configuration.

[0059] In one implementation of the fourth aspect, the method includes: providing the configuration message and / or the configuration update message as a multicast message.

[0060] The method of the fourth aspect and its implementation realizes the same advantages as the device of the second aspect and its corresponding implementation.

[0061] A fifth aspect of the present invention provides a computer program, the computer program including program code, and when the program code is executed on a computer, it is used to execute the method according to the third aspect, the fourth aspect or any of their implementations.

[0062] A sixth aspect of the present invention provides a non-transitory storage medium, the non-transitory storage medium stores executable program code, and when the executable program code is executed by a processor, it causes the execution of the method according to the third aspect, the fourth aspect or any of their implementations.

[0063] In summary, for the PSFCH power control at the first UE (target UE), a PSFCH power control configuration depending on the communication resources is provided, that is, a PSFCH power control configuration depending on the PSFCH resources used by the first UE to send feedback messages. The communication resources can be selected from the resource sets allocated by the second UE (source UE) or by the network; and / or the communication resources can be selected by the first UE (e.g., according to the Tx-Rx distance, SL-RSRP, the SL path loss of the first UE, the identifier of the first UE, or the identifier of the second UE).

[0064] In addition, since different types of feedback types (messages) and contents can be fed back in different communication resources, the PSFCH power control can also depend on the content and / or type of the feedback message that the first UE is sending to the second UE. For example, it depends on whether the first UE is sending HARQ feedback, that is, NACK or ACK feedback; or it depends on whether the first UE is sending feedback for PSCCH / PSSCH power control (i.e., SL-RSRP report); or it depends on whether the first UE is sending another type of feedback (e.g., CSI report).

[0065] The content of the PSFCH (feedback) power control can be based on the DL path loss and / or the SL path loss, or can be based on any other path loss, such as the path loss from the first UE to other UEs, or the path loss from the first UE to other gNBs.

[0066] In addition, the content of the PSFCH (feedback) power control can include the following exemplary parameters of the PSFCH power control:

[0067] · Maximum transmission power P MAX ;

[0068] · Nominal power P0 for each path loss based on which the PSFCH power control is performed;

[0069] · Factor α (i.e., the parameter for partial power control) for each path loss based on which the PSFCH power control is performed; and / or

[0070] · Fixed transmission power P Fixed to be used by the first UE, that is, when it does not exceed the maximum transmission power.

[0071] The configuration of PSFCH power control can be pre-configured (e.g., for out-of-coverage) or configured by the gNB or the second UE. The configuration of PSFCH power control for each communication resource can be signaled by the second UE or the gNB (network) in a multicast manner, i.e., signaled to a group of first UEs. In addition, the second UE can adjust / update the configuration of PSFCH power control according to the interference to the PSFCH communication resource at the second UE. Such interference can be caused by other transmissions to the second UE or transmissions to other devices.

[0072] In addition, the PSFCH communication resources used by the first UE to send feedback messages can be selected from the PSFCH resources or PSFCH resource sets allocated by the second UE or the gNB, and / or can be selected by the first UE according to the Tx-Rx distance, SL-RSRP, the SL path loss of the first UE, the identifier of the first UE, or the identifier of the second UE.

[0073] Some other definitions and information are provided below.

[0074] Feedback can generally be sent on time resources and / or frequency resources and / or code resources and / or spatial resources. For example, feedback can be sent via CDM and / or via FDM.

[0075] For unicast, one or more first UEs can use one or more dedicated (individual) PSFCH communication resources to send feedback messages. For example, the first UE can send HARQ feedback messages (i.e., ACK or NACK) in one or more dedicated PSFCH resources. For example, the first UE can send SL-RSRP for PSCCH / PSSCH power control in one or more dedicated PSFCH resources for feedback messages.

[0076] For multicast, one or more first UEs can also use one or more dedicated (individual) PSFCH resources for each first UE to send feedback. However, one or more shared PSFCH resources can also be used for the multicast feedback of the first UEs, e.g., to reduce the number of resources used for the feedback of the first UEs. In this case, multiple first UEs can share one or more PSFCH (communication) resources for multicast feedback.

[0077] For example, for HARQ feedback, multiple first UEs can be used to send NACK feedback messages on shared PSFCH communication resources. For this feedback, the first UEs can also be grouped according to the SL-RSRP and / or Tx-Rx distance of the first UEs, such that the first UEs with SL-RSRP and / or Tx-Rx distance within the ranges of SL-RSRP and / or Tx-Rx distance respectively share the PSFCH communication resources. The Tx-Rx distance can refer to the (relative) geographical distance between the second UE and the first UE. The Tx-Rx distance can be determined based on the location of the second UE and the location of the first UE. The Tx-Rx distance can also be determined based on the area ID associated with the location of the second UE and the area ID associated with the location of the first UE, where the area can be (pre)-configured with respect to a geographical area.

[0078] For HARQ feedback, for example, the first UEs with Tx-Rx distance within the Tx-Rx distance range can be used to send NACK feedback on the shared PSFCH communication resources associated with the Tx-Rx distance range. Specifically, the first UEs with Tx-Rx distance less than or equal to the Tx-Rx distance threshold (e.g., communication range requirement) can be used to send NACK feedback on the shared PSFCH communication resources. The SL-RSRP can refer to the SL reference signal reception power of the reference signal sent by the second UE at the first UE.

[0079] The first UEs can also be used to share one or more PSFCH communication resources for another type of multicast feedback (message), e.g., for the SL-RSRP report for PSCCH / PSSCH power control. Similar to HARQ feedback, multiple first UEs can be used to send feedback messages for power control on the shared PSFCH resources. For the HARQ feedback messages, the first UEs can also be grouped according to the SL-RSRP and / or Tx-Rx distance of the first UEs, such that the first UEs with SL-RSRP and / or Tx-Rx distance within the ranges of SL-RSRP and / or Tx-Rx distance respectively share the PSFCH communication resources for the SL-RSRP report.

[0080] In addition to the Tx-Rx distance or SL-RSRP or a combination of both, other criteria can be considered for grouping the feedback messages of the first UEs, or for determining when the first UEs send feedback messages on the shared PSFCH communication resources. For example, if the Tx-Rx distance is within a specific Tx-Rx distance range, and / or if its SL-RSRP is higher than a determined threshold, the TxUE sends feedback messages on a specific PSFCH communication resource.

[0081] Thus, for multicast feedback, one or more shared PSFCH communication resources may be associated with a range of SL-RSRP and / or Tx-Rx distance.

[0082] It should be noted that all devices, elements, units, and means described in this application may be implemented in software or hardware elements or any type of combination thereof. All steps performed by various entities described in this application and the functions described as being performed by various entities are intended to indicate that the corresponding entities are adapted or used to perform the corresponding steps and functions. Although in the description of the following specific embodiments, the specific functions or steps performed by external entities are not reflected in the description of the specific detailed elements of the entity performing the specific steps or functions, those skilled in the art should clearly understand that these methods and functions can be implemented by the corresponding hardware or software elements or any type of combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In conjunction with the accompanying drawings, the above aspects and their implementation manners will be elaborated in the description of the following specific embodiments. In the drawings:

[0084] Figure 1 Unicast and multicast transmissions and feedback are shown.

[0085] Figure 2 Feedback for unicast transmission is shown.

[0086] Figure 3 Feedback for multicast transmission is shown.

[0087] Figure 4 A first UE and a second UE according to an embodiment of the present invention are shown.

[0088] Figure 5 An example PSFCH power control configuration for each communication resource is shown.

[0089] Figure 6 An example of PSFCH power control adjusted for interference is shown.

[0090] Figure 7 An example of a PSFCH power control configuration is shown.

[0091] Figure 8 An example of a PSFCH power control configuration is shown.

[0092] Figure 9 An example of a PSFCH power control configuration depending on ACK or NACK feedback is shown.

[0093] Figure 10 A method for performing power control of SL feedback according to an embodiment of the present invention is shown.

[0094] Figure 11 An example of PSFCH power control depending on communication resources is shown.

[0095] Figure 12 An example of a PSFCH power control configuration depending on HARQ feedback is shown.

[0096] Figure 13 An example of a PSFCH power control configuration depending on feedback type and / or content is shown.

[0097] Figure 14 An example of an updated PSFCH power control configuration in multicast mode is shown.

[0098] Figure 15 Examples of different considerations for PSFCH power control depending on communication resources are shown.

[0099] Figure 16 Examples of PSFCH power control parameters determined at a first UE are shown. DETAILED DESCRIPTION

[0100] Figure 4 A first UE 400 (also hereinafter “target UE 400”) and a second UE 410 (also hereinafter “source UE 410”) according to an embodiment of the present invention are shown. The first UE 400 is used to perform power control on SL feedback, and / or the second UE 410 is used to support power control on SL feedback.

[0101] The first UE 400 is used to select a (specific) communication resource 401a for sending a feedback message 402 to the second UE 410 on the SL. The first UE 400 may select the communication resource 401a from a plurality of resources 401 or a set of resources 401 (resource set). In addition, the first UE 400 is used to select a power level for sending the feedback message 402, where the power level is selected based on the selected communication resource 401a. In addition, the power level may be selected based on the type and / or content of the feedback message 402. Then, the first UE 400 may be used to send the feedback message 402 to the second UE 410 on the selected communication resource 401a according to the selected power level.

[0102] Thus, the second UE 410 can be used to receive a feedback message 402 from the first UE 400. Additionally, the second UE 410 can be used to provide a configuration message 411 to the first UE 400 (e.g., before the first UE 400 sends the feedback message 402), where the configuration message 411 indicates at least one association between the communication resource 401a in the resource set 401 and a power control configuration (e.g., between the selected communication resource 401a and / or one or more unselected communication resources 401b and the power control configuration). The first UE 400 can receive the configuration message 411 and can select a power level based on the selected communication resource 401a according to the power control configuration associated with the communication resource 401a. However, this is optional, and the first UE 400 does not need the configuration message 411 to select a power level (thus the configuration message 411 is shown with a dashed line in Figure 4 ). It is also possible to pre-configure at least one association between the communication resource 401a in the resource set 401 and a power control configuration (e.g., between the selected communication resource 401a and / or one or more unselected communication resources 401b and the power control configuration).

[0103] The first UE 400 and / or the second UE 410 can each include a processor or processing circuitry (not shown) for performing, conducting, or initiating the various operations of the first UE 400 and / or the second UE 410 described herein. The processing circuitry can include hardware and / or the processing circuitry can be controlled by software. The hardware can include analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry can include components such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or a general-purpose processor.

[0104] The first UE 400 and / or the second UE 410 can also each include a memory circuit that stores one or more instructions that can be executed by the processor or processing circuitry (specifically, executed under the control of software). For example, the memory circuit can include a non-transitory storage medium that stores executable software code that, when executed by the processor or processing circuitry, causes the first UE 400 and / or the second UE 410 to perform various operations.

[0105] In one embodiment, the processing circuitry includes one or more processors and a non-transitory memory coupled to the one or more processors. The non-transitory memory may carry executable program code that, when executed by the one or more processors, causes the first UE 400 and / or the second UE 410 to perform, conduct, or initiate the operations or methods described herein.

[0106] The content of the preconfigured PSFCH power control configuration or PSFCH power control configuration message 411 associated with the communication resource 401a may include information on whether the PSFCH power control is based on the DL path loss and / or the SL path loss. Additionally, information on whether the PSFCH power control is based on any other path loss is included. For example, the PSFCH power control may be based on the path loss from the target UE 400 to one or more other UEs, or the PSFCH power control may be based on the path loss from the target UE 400 to one or more gNBs. Additionally, the content of the PSFCH power control configuration message 411 may include information on one or more of the following exemplary parameters for performing the PSFCH power control:

[0107] · Maximum transmit power P MAX 。

[0108] · Nominal power P0 for each path loss based on which the PSFCH power control is performed.

[0109] · Factor α (i.e., the parameter for partial power control) for each path loss based on which the PSFCH power control is performed.

[0110] · Fixed transmit power P that the first UE 400 is to use Fixed , i.e., in the case where it does not exceed the maximum transmit power.

[0111] Compared with configuring the PSFCH power control separately for each of the multiple target UEs 400, the PSFCH power control can be configured for each PSFCH communication resource, as Figure 5 shown. Additionally, the PSFCH power control may also be based on the content and / or feedback type of the feedback message 402.

[0112] PSFCH power control can have the following advantages according to the PSFCH resource configuration: The PSFCH power control (configuration) for each PSFCH resource can be determined by the source UE 410. For example, the source UE 410 can signal a power control configuration message 411 to the target UE 400 with the indication / determination of the PSFCH resource or as part of the control information. The PSFCH power control (configuration) for each feedback communication resource can alternatively be (pre)-configured at the target UE 400, or can be signaled to a group of target UEs 400 in a multicast manner instead of configuring each target UE 400 individually, i.e., instead of signaling a power control configuration message 411 (including power control parameters) to each target UE 400 individually.

[0113] In addition, the source UE 410 (as the receiver of the SL feedback message 402) can know the interference on a given PSFCH communication resource, and thus can adjust the PSFCH power control according to the interference on this PSFCH communication resource, as Figure 6 shown.

[0114] Therefore, the source UE 410 can update the PSFCH power control configuration on a specific PSFCH communication resource according to the determined interference, and then can signal the updated PSFCH power control configuration to one or more target UEs 400 through a configuration update message. Since the interference can be caused by adjacent PSFCH communication resources, the source UE 410 can also adjust the PSFCH control configuration of this PSFCH communication resource, for example, to reduce the transmission power, thereby reducing the interference that this PSFCH communication resource may cause to another PSFCH communication resource.

[0115] In addition, for multicast feedback on a shared communication resource, the PSFCH power control configuration for each PSFCH shared communication resource can be determined instead of configuring a dedicated PSFCH power control individually for each target UE 400 that performs feedback (sends the feedback message 402) on the shared communication resource. Specifically, this is advantageous when the number of target UEs 400 is large (e.g., when the number is greater than the available number of PSFCH communication resources), or when the number of target UEs 400 is unknown, or when the group / number of target UEs 400 for multicast transmission is unknown (e.g., connectionless multicast transmission), because signaling the PSFCH power control parameters to each target UE 400 or configuring the PSFCH power control individually for each target UE 400 can be avoided.

[0116] The target UEs 400 sharing one or more PSFCH resources may use the same PSFCH. However, this does not mean that the target UEs 400 sharing one or more PSFCH communication resources must send their feedback messages 402 with the same transmission power, as this may depend on specific parameters of each target UE 400. For example, it depends on the DL path loss to each target UE 400, and the DL path loss may be different.

[0117] In addition, the target UEs 400 may be grouped according to criteria such as the Tx-Rx distance (their distance to the source UE 410) or SL-RSRP for the feedback messages 402 of the target UEs 400. That is, the shared PSFCH resources may be associated with a range of Tx-Rx distances or SL-RSRP, and the target UEs sending feedback messages 402 on the shared PSFCH resources may have a Tx-Rx distance or SL-RSRP within a specific range of Tx-Rx distances or SL-RSRP. This can provide the following advantage: the PSFCH power control of the target UEs 400 sending feedback messages 402 on the shared PSFCH communication resources can be configured according to the range of Tx-Rx distance, SL-RSRP, or any other criteria used to group the target UEs 400, where the range is associated with the PSFCH resources. This is shown in Figure 7 shown.

[0118] It should be noted that the source UE 410 may know how one or more target UEs 400 are grouped for multicast feedback on the shared communication resources. Specifically, when considering several shared PSFCH resources (each associated with a different range of Tx-Rx distances (ranges 1 to N, as Figure 7 shown) or SL-RSRP ( Figure 6 not described therein)), the SL path loss of the target UEs 400 can be compensated, for example, by configuring different fixed transmission powers P Fixed for the feedback on each shared PFSCH resource, where the fixed transmission power depends on the range of Tx-Rx distance or SL-RSRP associated with the PSFCH resource. For example, the maximum transmission power or fixed transmission power of each feedback resource can be configured such that a higher Tx power is set on the feedback resource associated with a range having a lower SL-RSRP or a larger Tx-Rx distance, while a lower Tx power can be configured on the feedback resource associated with a range having a higher SL-RSRP or a smaller Tx-Rx distance, as Figure 8 shown.

[0119] The power control configuration can at least to some extent compensate for the SL path loss of one or more target UEs 400, and one or more target UEs 400 do not need to determine or obtain the SL path loss, that is, do not apply the PSFCH power control based on the SL path loss, while still obtaining the benefits of the SL path loss-based PSFCH power control. The PSFCH power control can be configured for each communication resource, that is, depending on its associated range. When grouping multiple target UEs 400, as described above, the SL path loss can also be derived based on the Tx-Rx distance and / or the range of SL-RSRP of a given target UE 400.

[0120] Configuring the PSFCH power control according to the content and / or type of the feedback message 402 can have the following advantages: In addition to the source UE 410, other UEs 900 can receive or overhear the selected content and / or certain types of feedback of the feedback. For example, in the case of resource reservation-based retransmission in mode 2, in order to support the release of one or more unused resources, it may be beneficial for other nearby UEs 900 to receive any ACK feedback of the unicast transmission. On the other hand, nearby other UEs 900 may not need to receive NACK feedback. Therefore, it may be beneficial to have different power control configurations for sending ACK and for sending NACK. For example, ACK can be sent with a higher maximum transmit power or a higher fixed transmit power, while NACK can be sent with a lower maximum transmit power or a lower fixed transmit power, as Figure 9 shown. The PSFCH power control configuration can also depend on the type of feedback, because for example, other nearby UEs 900 may not be interested in receiving the feedback for PSCCH / PSSCH power control, that is, it only causes interference.

[0121] Another advantage can be that for out-of-coverage scenarios, when the PSFCH power control is not based on the SL path loss, this may cause the target UE 400, for example, the feedback for multicast transmission, to send the feedback message 402 with the maximum transmit power, which may generate unnecessary interference or energy consumption at the target UE. If the target UEs 400 are grouped based on the Tx-Rx distance or SL-RSRP, the target UEs 400 can be used to send at a lower power, similar to that detailed above.

[0122] In addition, a flexible configuration of the PSFCH power control is achieved according to the communication resource, the feedback message content, and / or the feedback message type. The power control applies to unicast, multicast, and / or multicast feedback messages 402. In addition, the power control applies to in-coverage and / or out-of-coverage, and / or applies to the PSFCH power control based on the DL path loss and / or the SL path loss.

[0123] Figure 10 Method 1000 according to an embodiment of the present invention is shown, wherein the PSFCH power control for transmitting (1003) the feedback message 402 on the PSFCH resource i is determined based on the PSFCH power control (configuration) associated with the PSFCH resource i. The PSFCH resource 401a for transmitting (1003) the feedback message 402 can be determined or selected (1001) from a plurality or a set of resources 401 allocated, for example, by the source UE 410 or the network (e.g., for dedicated feedback). The resource 401a can also be selected (1001) according to, for example, the Tx-Rx distance, SL-RSRP, or SL path loss of the target UE 400, e.g., for multicast feedback on a shared communication resource. Then, the PSFCH power control is selected (1002) based on the selected communication resource 401a.

[0124] Figure 11 A flowchart is shown, wherein the PSFCH power control (performed by the target UE 400) is based on the PSFCH resource 401 (resource set), and the PSFCH resource 401 is associated with the range and / or threshold of the Tx-Rx distance and / or SL-RSRP, e.g., for multicast feedback on the shared PSFCH communication resource 401. One or more PSFCH power control configurations of one or more PSFCH resources 401 can be provided by the network or the source UE 410. One or more PSFCH power control configurations of one or more PSFCH resources 401 can also be pre-configured. The range and / or threshold of the Tx-Rx distance and / or SL-RSRP for enabling the target UE 400 to determine and select (1001) which PSFCH resource 401a is used for its feedback message 402 can be provided by the network or the source UE 410. After the target UE 400 determines the PSFCH resource 401a, the target UE 400 can then determine (1002) the PSFCH power control of the PSFCH resource 401a and can transmit (1003) the feedback message 402 using the PSFCH power control.

[0125] Figure 12A flowchart is shown, in which the PSFCH power control (performed by the target UE 400) is based on HARQ feedback. The PSFCH power control configuration for transmitting (1003a) NACK and the PSFCH power control for transmitting (1003b) ACK can be provided by the network or the source UE 410 to the target UE 400. The PSFCH power control configuration for transmitting NACK and the PSFCH power control configuration for transmitting (1003a) ACK can also be pre-configured. Based on whether the transmission is successful, the target UE 400 can determine (1200) whether to transmit an ACK or a NACK, and based on the selection (1001) of ACK or NACK communication resources, can decide (1002a / 1002b) which PSFCH power control configuration to use for the ACK or NACK feedback message 402.

[0126] Figure 13 A flowchart is shown, in which the network or the source UE 410 configures the PSFCH power control for the target UE 400 according to the feedback message type and / or content. The PSFCH power control configuration according to the feedback message type and / or content can also be pre-configured. The target UE 400 can determine (1001) the PSFCH resource 401a based on the type and content of the feedback message 402. Based on the PSFCH power control configuration, the target UE 400 can determine (1002) the PSFCH power control according to the type and / or the content of the feedback message 402 and based on the determined PSFCH resource 401a. For example, the target UE 400 can determine (1002) the PSFCH power control according to whether it transmits (1003) the HARQ feedback message 402 for unicast or for multicast, or according to whether it transmits (1003) an ACK, a NACK or only a NACK feedback, or according to whether it transmits information about the SL-RSRP for PSCCH / PSSCH power control as the feedback message 402 for unicast or for multicast, i.e., transmits the SL-RSRP report for unicast or for multicast. PSFCH PC conf. represents the PSFCH power control configuration.

[0127] Figure 14A signaling diagram is shown, in which one or more PSFCH power control configurations of one or more PSFCH resources 401 are signaled to one or more target UEs 400 in a multicast manner by the network 1400 or the source UE 410. One or more PSFCH power control configurations of one or more PSFCH resources 401 can be provided by the network 1400 or the source UE 410. One or more PSFCH power control configurations of one or more PSFCH resources can also be pre-configured. Thereafter, one or more target UEs 400 can determine (1002) PSFCH power control according to the PSFCH resource 401a that the target UE 400 will use for the feedback message 402. Then, one or more target UEs 400 send the feedback message 402 using the configured PSFCH power control. The source UE 410 can measure the interference to one or more PSFCH resources 401a, and based on the measurement, update the PSFCH power control configuration of the PSFCH resource 401. For example, if the PSFCH resource 401a experiences high interference, the source UE 410 can update the PSFCH power control configuration of the PSFCH resource 401a accordingly (in a multicast manner), that is, the PSFCH power control parameters, for example, one or more target UEs 400 that send the feedback message 402 on the PSFCH resource 401a use a higher maximum (or fixed) transmission power. In another example, the source UE 410 can update the PSFCH power control configuration of the PSFCH resource 401 (the PSFCH resource 401 that causes high interference to other PSFCH resources 401, for example) in a multicast manner, so that the PSFCH power control parameters of the PSFCH resource 401 are updated accordingly, for example, one or more target UEs 400 that send the feedback message 402 on the PSFCH resource 401a use a lower maximum (or fixed) transmission power.

[0128] Figure 15 A flowchart is shown, in which the PSFCH power control in some PSFCH resources 401 is only based on the SL path loss (set 1), the PSFCH power control in other PSFCH resources 401 is only based on the DL path loss (set 2), and the PSFCH power control in other PSFCH resources 401 is based on the SL path loss and the DL path loss (set 3). Different sets of PSFCH resources 401 can be configured by the network 1400, the source UE 410, or can be pre-configured. Different sets can also be based on the Tx-Rx distance and / or the SL-RSRP. When the PSFCH power control can be based on one or more other path losses (such as the path loss to other UEs 900 or the path loss to other gNBs), the diagram can also be extended to consider other sets of resources 401.

[0129] Figure 16 A flowchart is shown, in which a target UE 400 determines (1001) a PSFCH resource 401a for a feedback message 402, for example, based on the Tx-Rx distance, SL-RSRP, and / or SL path loss. Subsequently, the target UE 400 may determine (1002) one or more PSFCH power control parameters, i.e., P MAX or P Fixed . The target UE 400 that determines one or more PSFCH power control parameters has the following advantage, that is, the target UE 400 can determine a more accurate transmission power to compensate for the propagation conditions to the source UE 410, that is, more accurately compensate for the SL path loss. Then, the target UE 400 transmits (1003) the feedback message 402 using the configured PSFCH power control for the PSFCH resource 401a and one or more determined PSFCH power control parameters. The proposed embodiment can be combined with the PSFCH resource 401 associated with the Tx-Rx distance and / or SL-RSRP. In addition, this embodiment also enables the target UE 400 to substantially consider a finer granularity of the range of the Tx-Rx distance and / or SL-RSRP for determining (1002) the PSFCH power control parameters. In the case of PSFCH power control based on the SL path loss, the SL path loss as a parameter of the PSFCH power control can be determined based on the Tx-Rx distance and / or SL-RSRP.

[0130] The present invention has been described in connection with different embodiments and implementations as examples. However, based on the study of the drawings, the present invention, and the independent claims, those skilled in the art can understand and implement other variations when implementing the claimed invention. In the claims and the specification, the word "comprising" does not exclude other elements or steps, and the word "a" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. Listing certain measures in mutually different dependent claims does not mean that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A first user equipment (UE) for performing power control of sidelink (SL) feedback to the opposite side, characterized in that, Comprising a processor and a memory storing instructions, wherein, when the instructions are executed by the processor, they are used for: Selecting communication resources for sending a feedback message from the first UE to the second UE on the SL based on the distance between the first UE and the second UE, wherein the first UE is the target UE of unicast transmission or multicast transmission, the second UE is the source UE of the unicast transmission or multicast transmission, and different ranges of the distance between the first UE and the second UE correspond to different communication resources; and Selecting a power level for sending the feedback message, wherein the power level is selected based on the communication resources.

2. The first UE according to claim 1, characterized in that, For: Also selecting the power level based on the type and / or content of the feedback message.

3. The first UE according to claim 2, wherein: The type of the feedback message includes at least one of the following: - Hybrid Automatic Repeat reQuest (HARQ) feedback; - Reference Signal Received Power (RSRP) report; - Channel State Information (CSI) report.

4. The first UE according to claim 2 or 3, wherein: The content of the feedback message includes at least one of the following: - ACK feedback; - NACK feedback; - Only NACK feedback; - Feedback on the Physical Sidelink Control Channel (PSCCH); - Feedback on the Physical Sidelink Shared Channel (PSSCH).

5. The first UE according to any one of claims 1 to 3, characterized in that For: Also selecting the power level based on one or more path losses, wherein the one or more path losses include at least one of the following: - The SL path loss between the first UE and the second UE; - The downlink (DL) path loss between the first UE and the base station serving the first UE; - The path loss between the first UE and a third UE; - The path loss between the first UE and another base station.

6. The first UE according to any one of claims 1 to 3, characterized in that For: Also determining the power level based on whether the feedback message is for unicast feedback or for multicast feedback.

7. The first UE according to any one of claims 1 to 3, characterized in that, Also for: Selecting the communication resources from a resource set.

8. The first UE according to claim 7, wherein: The resource set is allocated to the first UE by the second UE or the base station serving the first UE.

9. The first UE according to any one of claims 1 to 3, characterized in that Also for: Further selecting the communication resources based on at least one of the following: - The SL path loss between the first UE and the second UE; - The RSRP at the first UE; - The identifier of the first UE; - The identifier of the second UE.

10. The first UE according to any one of claims 1 to 3, characterized in that, Also for: Receiving a configuration message or a configuration update message, wherein the configuration message or the configuration update message indicates at least one association between communication resources and power control configuration.

11. The first UE according to any one of claims 1 to 3, characterized in that, For selecting the power level based on at least one of the following: - The maximum power level; - A fixed power level; - One or more nominal power levels, each nominal power level being associated with a specific path loss used by the first UE to select the power level; - One or more factors for partial power control, each factor being associated with a specific path loss used by the first UE to select the power level.

12. The first UE according to any one of claims 1 to 3, characterized in that: The communication resources include time resources and / or frequency resources and / or spatial resources and / or code resources.

13. A method for performing power control of sidelink SL feedback, characterized in that, The method includes: Selecting communication resources for the first UE to send a feedback message to the second UE on the SL based on the distance between the first UE and the second UE, wherein the first UE is the target UE of unicast transmission or multicast transmission, the second UE is the source UE of the unicast transmission or multicast transmission, and different ranges of the distance between the first UE and the second UE correspond to different communication resources; and Selecting a power level for sending the feedback message, wherein the power level is selected based on the communication resources.

14. A computer-readable storage medium storing program code, characterized in that, When executed on a computer, the program code is used to execute the method according to claim 13.

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