DEVICES FOR POWER CONTROL FOR SIDELINK FEEDBACK

Abstract

A first user equipment (UE) is configured to perform power control for a sidelink (SL) feedback. The first UE is configured to select a communication resource for sending a feedback message over a SL to a second UE, and select a power level for sending the feedback message. The power level is selected based on the communication resource.

Claims

1. A first user equipment (UE) configured to perform power control for a sidelink (SL) feedback, the first UE being configured to: select a communication resource for sending a feedback message over a SL to a second UE; and select a power level for sending the feedback message, wherein the power level is selected based on the communication resource.

2. The first UE according to claim 1, wherein the first UE is further configured to: select the power level based further on at least one of a type of the feedback message or a content of the feedback message.

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

4. The first UE according to claim 2, wherein the content of the feedback message comprises at least one of: an acknowledgment (ACK) feedback; a negative acknowledgment (NACK) feedback; a NACK-only feedback; a feedback for Physical Sidelink Control Channel (PSCCH); or a feedback for Physical Sidelink Shared Channel (PSSCH).

5. The first UE according to claim 1, wherein the first UE is further configured to: select the power level based further on one or more path losses, wherein the one or more path losses comprise at least one of: a SL path loss between the first UE and the second UE; a Downlink (DL) path loss between the first UE and a base station configured to serve the first UE; a path loss between the first UE and a third UE; or a path loss between the first UE and another base station.

6. The first UE according to claim 1, wherein the first UE is further configured to: determine the power level based on whether the feedback message is configured for unicast feedback or groupcast feedback.

7. The first UE according to claim 1, wherein the first UE is further configured to: select the communication resource from a resource set.

8. The first UE according to claim 7, wherein the resource set is assigned to the first UE by the second UE or by a base station configured to serve the first UE.

9. The first UE according to claim 1, wherein the first UE is further configured to select the communication resource based on at least one of: a distance between the first UE and the second UE; a SL path loss between the first UE and the second UE; a Reference Signal Received Power (RSRP) at the first UE; an identifier of the first UE; or an identifier of the second UE.

10. The first UE according to claim 1, wherein the first UE is further configured to: receive a configuration message or a configuration update message, wherein the configuration message or the configuration update message indicates at least one association between a communication resource and a power control configuration.

11. The first UE according to claim 1, wherein 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 of the one or more nominal power levels being associated with a first path loss useable by the first UE to select the power level; or one or more factors useable for fractional power control, each factor of the one or more factors being associated with a second path loss useable by the first UE to select the power level.

12. The first UE according to claim 1, wherein the communication resource comprises at least one of: a time resource, a frequency resource, a spatial resource, or a code resource.

13. A second user equipment (UE) configured to perform power control for a sidelink (SL) feedback, the second UE being configured to: send a configuration message to a first UE, wherein the configuration message indicates at least one association between a communication resource and a power control configuration.

14. The second UE according to claim 13, wherein the second UE is further configured to: receive a feedback message on a communication resource from the first UE; determine an interference at the second UE on the communication resource; and provide, based on the determined interference, a configuration update message to the first UE, wherein the configuration update message indicates at least one updated association between the communication resource and the power control configuration.

15. The second UE according to claim 13, wherein the second UE is further configured to: send at least one of the configuration message or the configuration update message as groupcast message to a plurality of first UEs.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0084] The above described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

[0085] FIG. 1 shows unicast and groupcast transmissions and feedback.

[0086] FIG. 2 shows a feedback to a unicast transmission.

[0087] FIG. 3 shows a feedback for a groupcast transmission.

[0088] FIG. 4 shows a first UE and a second UE according to embodiments of the invention.

[0089] FIG. 5 shows an example PSFCH power control configuration per communication resource.

[0090] FIG. 6 shows an example of PSFCH power control adapted to interference.

[0091] FIG. 7 shows an example of a PSFCH power control configuration.

[0092] FIG. 8 shows an example of a PSFCH power control configuration.

[0093] FIG. 9 shows an example of a PSFCH power control configuration depending on the ACK or NACK feedback.

[0094] FIG. 10 shows method for performing power control for SL feedback according to an embodiment of the invention.

[0095] FIG. 11 shows an example of a PSFCH power control depending on a communication resource

[0096] FIG. 12 shows an example of a PSFCH power control configuration depending on a HARQ feedback.

[0097] FIG. 13 shows an example of a PSFCH power control configuration depending on feedback type and/or content.

[0098] FIG. 14 shows an example of an updated PSFCH power control configuration in a groupcast way.

[0099] FIG. 15 shows an example of different Considerations for PSFCH power control depending on a communication resource.

[0100] FIG. 16 shows an example of PSFCH power control parameters determined at the first UE.

DETAILED DESCRIPTION OF EMBODIMENTS

[0101] FIG. 4 shows a first UE 400 (in the following also the “Target UE 400”) and a second UE 410 (in the following also the “Source UE 410”) according to embodiments of the invention. The first UE 400 is configured to perform power control for SL feedback, and/or the second UE 410 is configured to support a power control for SL feedback.

[0102] The first UE 400 is configured to select a (certain) communication resource 401a for sending a feedback message 402 over a SL to the second UE 410. The first UE 400 may select this communication resource 401a from a plurality of resources 401 or set of resources 401 (resource set). Further, the first UE 400 is configured to select a power level for sending the feedback massage 402, wherein the power level is selected based on the selected communication resource 401a. In addition, the power level may be selected based on a type and/or a content of the feedback message 402. The first UE 400 may then be configured to send the feedback message 402 to the second UE 410 on the selected communication resource 401a according to the selected power level.

[0103] The second UE 410 may thus be configured to receive the feedback message 402 from the first UE 400. Further, the second UE 410 can be configured to provide a configuration message 411 to the first UE 400 (e.g., before the first UE 400 sends a feedback message 402), wherein the configuration message 411 indicates at least one association between a communication resource 401a, e.g. between the selected communication resource 401a and/or one or more unselected communication resources 401b, of the resource set 401, and a power control configuration. The first UE 400 may receive the configuration message 411, and may select the power level based on the selected communication resource 401a according to the power control configuration, which is associated with that communication resource 401a. However, this is optional, and the first UE 400 does not need the configuration message 411 to select the power level (thus the configuration message 411 is illustrated with a dashed line in FIG. 4). The at least one association between a communication resource 401a, e.g. between the selected communication resource 401a and/or one or more unselected communication resources 401b, of the resource set 401, and a power control configuration can also be preconfigured.

[0104] The first UE 400 and/or the second UE 410 may each comprise a processor or processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the first UE 400 and/or second UE 410 described herein. The processing circuitry may comprise hardware and/or the processing circuitry may be controlled by software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors.

[0105] The first UE 400 and/or second UE 410 may further each comprise memory circuitry, which stores one or more instruction(s) that can be executed by the processor or by the processing circuitry, in particular under control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the first UE 400 and/or second UE 410 to be performed.

[0106] In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the first UE 400 and/or second UE 410 to perform, conduct or initiate the operations or methods described herein.

[0107] The content of the PSFCH power control configuration message 411 or a preconfigured PSFCH power control configuration which is associated with a communication resource 401a may include the information, whether the PSFCH power control is based on the DL pathloss and/or on the SL pathloss. Further, the information, whether it is based on any other pathloss, e.g. it could be based on a pathloss from the Target UE 400 to one or more other UE(s), or it could be based on a pathloss from the Target UE 400 to one or more gNBs. In addition, 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: [0108] A maximum transmit power P.sub.MAX. [0109] A nominal power P.sub.0, for each of the pathloss(es), on which the PSFCH power control is based. [0110] A factor α (i.e. parameter used for fractional power control), for each of the pathloss(es), on which the PSFCH power control is based. [0111] A fixed transmit power P.sub.Fixed to be used by the first UE 400, i.e. if it does not exceed the maximum transmit power.

[0112] In contrast to configuring the PSFCH power control for each of multiple Target UEs 400 individually, the PSFCH power control can be configured per PSFCH communication resources, as it is illustrated in FIG. 5. In addition, the PSFCH power control may also be based on the content of the feedback message 402 and/or feedback type.

[0113] Configuring the PSFCH power control in dependence of the PSFCH resource, may have the advantage that the PSFCH power control (configuration) for each PSFCH resource may be determined by the Source UE 410. For instance, the Source UE 410 can signal the power control configuration message 411 with the indication/determination of the PSFCH resources or as a part of control information to the Target UE(s) 400. The PSFCH power control (configuration) per feedback communication resource may alternatively be (pre)configured at the Target UE(s) 400, or it may be signaled in a groupcast way, to a group of Target UEs 400, instead of configuring each Target UE 400 separately, i.e. instead of signaling the power control configuration message 411 (including power control parameters) to each Target UE 400 separately.

[0114] Furthermore, the Source UE 410, as a receiver of the SL feedback message 402, may be aware of interference on a given PSFCH communication resource, and thereby may adapt the PSFCH power control depending on the interference on that PSFCH communication resource, as it is shown in FIG. 6.

[0115] Thus, the Source UE 410 may update the PSFCH power control configuration on a certain PSFCH communication resource depending on determined interference, and may afterwards signal the updated PSFCH power control configuration via a configuration update message to the Target UE(s) 400. As the interference can result from a neighboring PSFCH communication resource, the Source UE 410 may also adapt the PSFCH control configuration of that PSFCH communication resource, e.g., to reduce the transmit power, and in turn reduce the interference that this PSFCH communication resource may cause on another PSFCH communication resource.

[0116] In addition, for groupcast feedback over shared communication resources, the PSFCH power control configuration for each PSFCH shared communication resource may be determined, instead of configuring separately a dedicated PSFCH power control for each of the Target UEs 400 that perform the feedback (send the feedback message 402) over the shared communication resources. In particular, this is of an advantage, when the number of Target UEs 400 is large (e.g., when the number is larger 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 groupcast transmission is not known (e.g., connectionless groupcast transmission), because signaling PSFCH power control parameters to each Target UE 400, or configuring the PSFCH power control for each Target UE 400, separately, can be avoided.

[0117] Target UEs 400 sharing one or more PSFCH resources may use the same PSFCH. However, this does not necessarily mean that the Target UE(s) 400 sharing the one or more PSFCH communication resources would have to send their feedback messages 402 with the same transmit power, as this may depend on specific parameters of each Target UE 400, e.g. on the DL pathloss to each Target UE 400, which may be distinct.

[0118] Furthermore, the Target UEs 400 could be grouped for their feedback messages 402, e.g., according to criteria like Tx-Rx distance (their distance to the Source UE 410) or SL-RSRP. That is, a shared PSFCH resource may be associated with a range of Tx-Rx distances, or SL-RSRPs, and Target UEs sending feedback messages 402 on a shared PSFCH resource may have a Tx-Rx distance or SL-RSRP within a certain range of Tx-Rx distances or SL-RSRPs. This can offer the advantage that the PSFCH power control of the Target UEs 400, which send feedback messages 402 on a shared PSFCH communication resource, can be configured depending on the range of Tx-Rx distances, SL-RSRPs, or any other criteria that is used to group the Target UEs 400, wherein the range is associated with the PSFCH resource. This is shown in FIG. 7.

[0119] Notably, the Source UE 410 may be aware of how the Target UE(s) 400 are grouped for the groupcast feedback over shared communication resources. In particular, when considering several shared PSFCH resources, each one being associated with a different range of Tx-Rx distances (e.g. ranges 1 to N shown in FIG. 7) or SL-RSRPs (not depicted in FIG. 6), the SL pathloss of the Target UEs 400 may be compensated, for example, by configuring a different fixed transmit power P.sub.Fixed for the feedback on each shared PFSCH resource, wherein the fixed transmit power depends on the range of Tx-Rx distances or SL-RSRPs associated with the PSFCH resource. For instance, the maximum transmit power or a fixed transmit power for each feedback resource may be configured such that a higher Tx power is set on feedback resources associated with ranges with lower SL-RSRP or larger Tx-Rx distances, whereas lower Tx power may be configured on feedback resources associated with ranges of higher SL-RSRP or smaller Tx-Rx distances, as depicted in FIG. 8.

[0120] The power control configuration may enable compensating, at least to some extent, for the SL pathloss of the Target UE(s) 400, without the Target UE(s) 400 requiring to determine or to obtain the SL pathloss, i.e., without applying SL pathloss based PSFCH power control, while still obtaining benefits of a SL based pathloss PSFCH power control. The PSFCH power control can be configured for each communication resource, i.e. depending on its associated range. When multiple Target UEs 400 are grouped, as described above, the SL pathloss could also be derived based on the Tx-Rx distance and/or SL-RSRP range of the given Target UE 400.

[0121] Configuring the PSFCH power control depending on the content and/or type of feedback message 402 can have the advantage that other UEs 900, besides the Source UE 410, could receive or overhear selected content and/or certain types of feedback. For example, it may be beneficial for other, nearby, UEs 900 to receive any ACK feedback of a unicast transmission, in order to support release of unused resource(s), in case of resource reservation based retransmissions for mode 2. On the other hand, it may not be necessary for other, nearby, UEs 900 to receive NACK feedback, and hence, it may be advantageous that the power control configuration for sending the ACK and for sending NACK is different. For example, ACK may be sent with a higher maximum transmit power or a higher fixed transmit power, whereas NACK may be sent with a lower maximum transmit power or a lower fixed transmit power—as is depicted in FIG. 9. The PSFCH power control configuration may also depend on the type of feedback, as for example other UEs 900 nearby may not be interested in receiving feedback for PSCCH/PSSCH power control, i.e. it would only result in interference.

[0122] Another advantage can be that for out-of-coverage scenarios, when the PSFCH power control is not based on the SL pathloss, this may result in the Target UEs 400, e.g., for feedback of a groupcast transmission, to send the feedback message 402 at a maximum transmit power, which may cause unnecessary interference or energy consumption at a Target UE. If the Target UEs 400 are grouped based on a Tx-Rx distance or SL-RSRP, the Target UEs 400 may be configured to transmit at a lower power, similarly as detailed above.

[0123] Further, flexible configuration for PSFCH power control is enabled, depending on the communication resource, feedback message content, and/or feedback message type. The power control is applicable to unicast, groupcast, and/or groupcast feedback messages 402. Further, the power control is suitable for in-coverage and/or out-of-coverage, and/or for PSFCH power control based on DL pathloss and/or SL pathloss.

[0124] FIG. 10 shows a method 1000 according to an embodiment of the invention, wherein the PSFCH power control for sending 1003 the feedback message 402 on the PSFCH resource i is determined based on the PSFCH power control (configuration) associated with that PSFCH resource i. The PSFCH resource 401a for sending 1003 the feedback message 402 may be determined or selected 1001 from a plurality or set of resources 401, for example, assigned by the Source UE 410 or by the network (e.g. for a dedicated feedback). The resource 401a may also be selected 1001, e.g., depending on the Tx-Rx distance, SL-RSRP or SL pathloss of a Target UE 400, e.g., for groupcast feedback over shared communication resources. The PSFCH power control is then selected 1002 based on the selected communication resource 401a.

[0125] FIG. 11 depicts a flowchart, wherein the PSFCH power control (performed by the Target UE 400) is based on PSFCH resources 401 (resource set), which are associated with ranges and/or thresholds of the Tx-Rx distance and/or SL-RSRP, e.g. for groupcast feedback over shared PSFCH communication resources 401. The PSFCH power control configuration(s) for the PSFCH resource(s) 401 may be provided by the network or the source UE 410. The PSFCH power control configuration(s) for the PSFCH resource(s) 401 may also be preconfigured. The ranges and/or thresholds of the Tx-Rx distance and/or SL-RSRP for enabling a Target UE 400 to determine and select 1001, which PSFCH resource 401a to use for its feedback message 402, may be provided by the network or the Source UE 410. After the Target UE 400 has determined the PSFCH resource 401a, it may then determine 1002 the PSFCH power control for that PSFCH resource 401a, and may send 1003 the feedback message 402 with that PSFCH power control.

[0126] FIG. 12 depicts a flowchart, wherein the PSFCH power control (performed by the Target UE 400) is based on HARQ feedback. The PSFCH power control configuration for sending 1003a NACK and the PSFCH power control for sending 1003b ACK may be provided to the Target UE 400 by the network or the source UE 410. The PSFCH power control configuration for sending NACK and the PSFCH power control configuration for sending 1003a ACK could also be preconfigured. Based on whether a transmission was successful or not, a Target UE 400 may determine 1200, whether to send ACK or NACK, and based on selecting 1001 the ACK or NACK communication resource, it may decide 1002a/1002b which PSFCH power control configuration to use for the ACK or NACK feedback message 402.

[0127] FIG. 13 shows a flowchart, wherein the network or Source UE 410 configures the PSFCH power control for a Target UE 400, depending on the feedback message type and/or content. The PSFCH power control configurations depending on the feedback message type and/or content could also be preconfigured. The Target UE 400 may 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 may determine 1002 the PSFCH power control depending on the type of the feedback message 402 and/or on the content of the feedback message 402, and based on the determined PSFCH resource 401a. For example, the Target UE 400 may determine 1002 the PSFCH power control depending on whether it is sending 1003 a HARQ feedback message 402 for unicast or for groupcast, or depending on whether it is sending 1003 ACK, NACK, or NACK-only feedback, or depending on whether it is sending information about the SL-RSRP for PSCCH/PSSCH power control for unicast or groupcast as feedback message 402, i.e. SL-RSRP report for unicast or groupcast. PSFCH PC conf. stands for PSFCH power control configuration.

[0128] FIG. 14 shows a signaling chart, wherein the PSFCH power control configuration(s) for the PSFCH resource(s) 401 is signaled by the network 1400 or by the Source UE 410 to Target UE(s) 400 in a groupcast way. The PSFCH power control configuration(s) for the PSFCH resource(s) 401 may be provided by the network 1400 or source UE 410. The PSFCH power control configuration(s) for the PSFCH resource(s) could also be preconfigured. Afterwards, the Target UE(s) 400 may determine 1002 the PSFCH power control depending on the PSFCH resource 401a that the Target UE 400 will use for the feedback message 402. The Target UE(s) 400 then sends the feedback message 402 with the configured PSFCH power control. The Source UE 410 may measure the interference on the PSFCH resource(s) 401a and based on the measurements it can update the PSFCH power control configuration for the PSFCH resources 401. For example, if a PSFCH resource 401a experiences high interference, the Source UE 410 can update (in a groupcast way) accordingly the PSFCH power control configuration, i.e. the PSFCH power control parameters, for that PSFCH resource 401a, e.g. Target UE(s) 400 sending feedback message 402 on that PSFCH resource 401a employs a higher maximum (or fixed) transmit power. In another example, the Source UE 410 can update (in a groupcast way) the PSFCH power control configuration for PSFCH resources 401, which cause high interference, e.g. to other PSFCH resources 401, such that the PSFCH power control parameters for the PSFCH resources 401 are updated accordingly, e.g. Target UE(s) 400 sending the feedback message 402 on that PSFCH resource 401a employ a lower maximum (or fixed) transmit power

[0129] FIG. 15 shows a flowchart, wherein the PSFCH power control in some PSFCH resources 401 are based only on the SL pathloss (set 1), in other PSFCH resources 401 it is based only on the DL pathloss (set 2), and in other PSFCH resources 401 it is based on the SL pathloss and the DL pathloss (set 3). The different sets of PSFCH resources 401 can be configured by the network 1400, by the Source UE 410 or could be preconfigured. The different sets could also be based on the Tx-Rx distance and/or SL-RSRP. The figure may also be extended to consider other sets of resources 401, when the PSFCH power control can be based on other pathloss(es), e.g. the pathloss to other UEs 900 or the pathloss to other gNBs.

[0130] FIG. 16 shows a flowchart, wherein a Target UE 400 determines 1001 a PSFCH resource 401a for the feedback message 402, e.g., based on the Tx-Rx distance, SL-RSRP and/or SL pathloss, and afterwards the Target UE 400 may determine 1002 one or more PSFCH power control parameters, i.e. P.sub.MAX or P.sub.Fixed, based on the Tx-Rx distance, SL-RSRP or SL pathloss, as well as on a PSFCH power control configuration for that PSFCH resource 401a, which is provided by the network 1400 or Source UE 410, or can be preconfigured. The Target UE 400 determining one or more PSFCH power control parameters provides the advantage that the Target UE 400 can determine a more precise transmit power to compensate for the propagation conditions to the Source UE 410, i.e. to compensate more precisely for the SL pathloss. The Target UE 400 then sends 1003 the feedback message 402 with the configured PSFCH power control for that PSFCH resource 401a and the one or more determined PSFCH power control parameters. This proposed embodiment may be combined with the PSFCH resources 401 being associated to Tx-Rx distance and/or SL-RSRP. In addition, this embodiment also allows for a Target UE 400 to basically consider a finer granularity of Tx-Rx distance and/or SL-RSRP ranges for the determination 1002 of the PSFCH power control parameters. In case of SL pathloss based PSFCH power control, the SL pathloss, as parameter of the PSFCH power control, can be determined based on the Tx-Rx distance and/or SL-RSRP.

[0131] The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.