WO2022213275A1

WO2022213275A1 - Resource allocation enhancements for sl

Info

Publication number: WO2022213275A1
Application number: PCT/CN2021/085690
Authority: WO
Inventors: Lung-Sheng Tsai; Tao Chen
Original assignee: Mediatek Inc.
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2022-10-13

Abstract

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus about resource allocation for SL. For SL resource allocation, the Rx UE can transmit the assistance information to assist Tx UE's resource selection. For the reserved resource indicated in SCI from the peer Tx UE, the Rx UE can indicate the resources are not preferred via the signaling, e.g., one bit in the physical SL feedback channel (PSFCH) to the peer Tx UE ifthe reserved resources are not preferred based on the sensing results at Rx UE. On the other hand, the Rx UE can transmit at least SCI carrying resource reservation information from the peer Tx UE at least to the potential interfering UEs for resource collision avoidance ifthe reserved resources is preferred/acceptable based on the sensing results at Rx UE.

Description

RESOURCE ALLOCATION ENHANCEMENTS FOR SL

FIELD

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus about SL resource allocation enhancement.

BACKGROUND

In 5G new radio, V2X sidelink (SL) communication can be supported by the unicast, groupcast and broadcast communications. However, there are some issues to be addressed for SL resource allocation to improve the reliability and reduce the latency of SL communications.

SUMMARY

For SL resource allocation, the Rx UE assisted resource allocation mechanism can be applied to improve the reliability and reduce the overall latency for SL communication, which can work independently or jointly with Tx UE based sensing and resource allocation mechanism.

In an aspect of the disclosure, it relates generally to wireless communications, and, more particularly, to methods and apparatus about resource allocation for SL. For SL resource allocation, the Rx UE can transmit the assistance information to assist Tx UE’s resource selection. For the reserved resource indicated in SCI from the peer Tx UE, the Rx UE can indicate the resources are not preferred via the signaling, e.g., one bit in the physical SL feedback channel (PSFCH) to the peer Tx UE if the reserved resources are not preferred based on the sensing results at Rx UE. On the other hand, the Rx UE can transmit at least SCI carrying resource reservation information from the peer Tx UE at least to the potential interfering UEs for resource collision avoidance if the reserved resources is preferred/acceptable based on the sensing results at Rx UE.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of proposed method or procedure to assist Tx UE’s transmission.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It is understood that the specific order or hierarchy of blocks in the processes/flowcharts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

This inventions relates generally to wireless communications, and, more particularly, to methods and apparatus about resource allocation for SL. For SL resource allocation, the Rx UE can transmit the assistance information to assist Tx UE’s resource selection. For the reserved resource indicated in SCI from the peer Tx UE, the Rx UE can indicate the resources are not preferred via the signaling, e.g., one bit in the physical SL feedback channel (PSFCH) to the peer Tx UE if the reserved resources are not preferred based on the sensing results at Rx UE. On the other hand, the Rx UE can transmit at least SCI carrying resource reservation information from the peer Tx UE at least to the potential interfering UEs for resource collision avoidance if the reserved resources is preferred/acceptable based on the sensing results at Rx UE.

As illustrated in Fig. 1, the peer Tx UE is communicating with the peer Rx UE whereas the other Tx UE (s) is communicating with the other Rx UE (s) . Accordingly, the other Tx UE’s transmission to the other Rx UE may cause the interference at the peer Rx UE if lacking of the efficient coordination between the peer Tx UE and the other Tx UE.

In Step 1, the peer Tx UE will send the data associated with the control channel which further (e.g., sidelink control information) carries the resource reservation information to indicate the time/frequency resources reserved for future transmissions.

In Step 2, upon receiving the SCI information from the peer Tx UE, the peer Rx UE will check whether the resources reserved in SCI is acceptable or preferred according to the Rx UE’s sensing results in the past. To be noted, sensing by Rx UE will collect the channel priority and resource reservation info obtained from the SCI received from any UE (i.e., not only the peer Tx UE) , as well as RSRP results measured on the DMRS of the received SCI and/or the associated data DMRS. Therefore, upon reception of the SCI from the peer Tx UE, the Rx UE can check the reserved resources in SCI and compare the RSRP performances of the peer Tx UE and the other potential interfering UEs with the same resource reservation according to the sensing results in the past. For example, if RSRP of the peer Tx UE is higher than RSRP of the potential interfering UE, the reserved resources by the peer Tx UE is determined as “preferred” from the peer Rx UE perspective. Otherwise, the reserved resources is deemed as “non-preferred” . Additionally, the comparison of RSRP performances can further taking into account the priority levels between the peer Tx UEs and the other potential interfering UEs. For example, the RSRP offset can be derived or (pre-) configured based on the priority levels of the peer Tx UE and the other potential interfering UEs. For the different pair of priority levels between the peer Tx UE and potential interfering UEs, the RSRP offset can be different. Then the peer Rx UE will compare the RSRP difference between the peer Tx UE and the potential interfering UE with an RSRP offset value derived from the function of the priority levels of the peer Tx UE and the potential interfering UE. If the RSRP difference is higher (or lower) than the RSRP offset value, the reserved resources are identified as “preferred” . Otherwise, the reserved resources will be identified as “non-preferred” .

According to the decision of “preferred” or “non-preferred” resources as above, the peer Rx UE will send the assistance information to the peer Tx UE and/or the potential interfering UEs.

As shown in step 2. A, if the reserved resources are identified as “non-preferred” , the peer Rx UE will send the “non-preferred” indication (NPI) to the peer Tx UE. Such indication (e.g., one bit or multiple bits) can be carried in the physical sidelink feedback channel (PSFCH) from the peer Rx UE to the peer Tx UE. Additionally, there can be multiplexing with SL A/N bit or not depending on the transmission timing and/or (pre-) configuration. If there is no multiplexing between such indication bit with A/N bit, the PSFCH may only carry one of them each time by using the different time/frequency/sequence resources for differentiation. If there is multiplexing between such indication bit with A/N bit, the PSFCH can carry a few more bits each time (e.g., two bits with one for A/N and the other for “non-preferred” indication) . In this case, it may require 4 PSFCH resources (sequences) to indicate two bits information. PSFCH resources used for transmission can be determined by the function of source and/or dest UE IDs. If it is groupcast transmission, the PSFCH resources used for transmission can derived from the function of the group ID and/or member ID in the group.

PSFCH may carry one or multiple bits for “non-preferred” resource indication. If it is one bit, then the“non-preference” indication can be corresponding to the 2 ^nd resource in SCI (i.e., the 1 ^st reserved resource) . Alternatively, the “non-preferred” indication can be corresponding to all resources in SCI. in this case, some rules can be derived to determine the setting. For example, if any of one of the reserved resources is not preferred, this bit will be set and sent. If all of the resources are preferred or acceptable, this bit will not be sent.

If there are multiple bits for indication, then the “non-preferred” indication can be corresponding to each reserved resource in SCI. For example, two bits of the “non-preferred” indication can be corresponding to the 2 ^nd resource in SCI (i.e., the 1 ^st reserved resource) and the 3 ^rd resource in SCI (i.e., 2 ^nd reserved resource) respectively.

Additionally, for the transmission timing of the “non-preferred” indication, it can be the same timing as A/N transmission (corresponding to the received SCI/data from the peer Tx UE) if the multiplexing is(pre-) configured. Alternatively, the “non-preferred” indication can be sent in its own timing, e.g., x slots before the time instant of the reserved resource (s) wherein x can be the processing time at the peer Tx UE for processing of the received indication and performing resource re-selection if needed. Alternatively, the A/N timing may be multiplexed with the “non-preferred” indication for transmission but following the timing of the “non-preferred” indication, i.e., y slots before the time instant of the reserved resource (s) wherein y can be the processing time at the peer Tx UE for processing of the received indication, performing resource re-selection if needed, processing of A/N bit and preparation ofretransmission or new transmission. To be noted, x and y can be same or different, which can be up to (pre-) configuration.

Besides, upon reception of the SCI/data from the peer Tx UE, the Rx UE is triggered for such NPI transmission if the reserved resource (s) is identified as “non-preferred” . Additionally, there can be the delay budget for the transmission of the “non-preferred” indication, e.g., x or y slots before the reserved resource (s) . If the delay budget is exceeded, the Rx UE can drop the transmission of the indication.

As shown in Step 2. B, if the reserved resources are identified as “preferred” a, the peer Rx UE can send SCI (s) (1 ^st and/or 2 ^nd SCI) with/without the associated (dummy) data targeting to the potential other Tx UEs. For ease of presentation, we call this additional SCI (s) “protecting SCI (s) ” to protect resources reserved by peer-Tx UE. The SCI (s) can at least carry the resource reservation information, the priority information and/or the source UE ID information obtained from the SCI (s) of the peer Tx UE. For example, the 1 ^st SCI can carry the resource reservation information and the priority information obtained from the 1 ^st SCI of the peer Tx UE. The 2 ^nd SCI can carry the peer Tx UE’s source ID (rather than peer Rx UE’s source ID) in the field of source UE ID. So it will look like the forwarding of the SCI from the peer Tx UE for the larger coverage to avoid the hidden node problem. Additionally, Rx UE may include the additional resource reservation information in the SCI if needed. In this case, the Rx UE may use its own UE ID as the source UE ID in the 2 ^nd SCI. Moreover, there could be the dummy data or not associated with the SCI transmission.

In another design example, an Rx-UE may send protecting SCI by only 1 ^st SCI but without 2 ^nd SCI. The 1 ^st SCI can provide information related to source UE ID so that the peer Tx UE can know this protecting SCI is (or is very likely) corresponding to its own reservation to avoid confusion in resource reservation. In other words, source UE ID implied by this protecting SCI is the same as the peer Tx UE’s ID. This can be achieved in the following candidate solutions:

1) The protecting 1 ^st SCI carries peer Tx UE’s ID,

2) The protecting 1 ^st SCI carries part of the peer Tx UE’s ID (e.g., a fixed number of MSBs/LSBs of the ID instead ofall bits of the UE ID) , or

3) The protecting 1 ^st SCI directly indicates this is a protecting SCI and let peer Tx-UE decides if this SCI is protecting SCI or not by checking fields in this protecting SCI and the 1 ^st SCI had been sent. For example, the peer Tx-UE may recognize this protecting SCI is due to its own transmission if reserved time/frequency resources implied by this protecting SCI are identical to those previously reserved by itself.

In step 2. B, the peer Rx UE needs to select time-frequency resource to send the protecting SCI (s) . The peer Rx UE sends protecting SCI (s) to protect resources that are indicated by “frequency resource assignment” and “time resource assignment” fields and a resource reservation period in the received SCI sent by the peer Tx UE. The resources to be protected can be:

Case 1: one or two reserved resources at time slot t=t1 and t2; they are indicated by the SCI sent by peer Tx UE at time slot t=t0;

Case 2: one or more than one of the reserved resources at time slot t=t0+P, t1+P, t2+P, if the peer Tx UE indicates periodic resource reservation with a resource reservation period, P, greater than 0.

For both Case 1 and Case 2, the protecting SCI should indicate resource (s) to be protected by reusing its own “frequency resource assignment” and “time resource assignment” fields. Sensing based resource-selection procedure (e.g., UE procedure for determining the subset of resources to be reported to higher layers in PSSCH resource selection in sidelink resource allocation mode 2 defined in NR) can be applied to select a resource for sending the protecting SCI. However, the following constraints should be introduced:

1) A delay budget constraint should be introduced so that the protecting SCI can be received early enough and allows that all potential co-channel Tx UEs have sufficient processing time (denoted by T _proc) to decode the protecting SCI and then avoid resource collision.

2) The resource selection should consider the indicating range of time slot offset for the reserved resource, because the bit-width of time slot indication is limited. For example, “time resource assignment” field defined in SCI format 1-A can support indication for the time slot offset between the first reserved resource (which is the resource occupied by the protecting SCI) and the second/third reserved resource no more than K=31 slots.

Taking Case 2 for example, to protect the resource at time slot t=t0+P, the peer Rx UE may send protecting SCI at time slot t _protect such that t _protect is at most K slots earlier than the time slot t0+P. Similarly, for Case 1, the peer Rx UE may send protecting SCI at time slot t _protect such that t _protect is at most K slots earlier than the time slot t1.

Because SCI format 1-A can indicate at most three reserved resources, it may be beneficial to allow the protecting SCI to indicate at most N reserved resources, which include the resource occupied by the protecting SCI itself and the three reserved resources to be protected, with N>3. As a result, new definitions for “frequency resource assignment” and “time resource assignment” in SCI are needed to allow TRIV and FRIV representations supporting N>3. The value of N for protecting SCI can be separately (pre-) configured in contrast to the parameter sl_MaxNumPerReserve which stands for the maximum number of reserved resource per reservation and is already defined in NR.

Besides, upon reception of the SCI/data from the peer Tx UE, the Rx UE is triggered for such protecting SCI transmission if the reserved resource (s) is identified as “preferred” . Additionally, there can be the delay budget for the transmission of the SCI (s) information, e.g., x or y slots before the reserved resource (s) . If the delay budget is exceeded, the Rx UE can drop the transmission of the SCI (s) w/wo (dummy) data.

As shown in Step 3. A, upon reception of the “non-preferred” indication in Step 2. A, the resource re-selection can be triggered at the peer Tx UE to avoid the resources marked as “non-preferred” by the peer Rx UE.

As shown in Step 3. B-2, upon reception of the SCI (s) w/wo (dummy) data in Step 2. B, the peer Tx UE can know it is own reservation according to the source UE ID (i.e., source UE ID is same as the peer Tx UE’s ID) so that the corresponding reception and/or sensing can be skipped/dropped to avoid confusion of the resource selection.

As shown in Step 3. B-1, upon reception of the SCI (s) w/wo (dummy) data in Step 2. B, the other Tx UE (s) (or potential interfering UEs) can receive the SCI (s) and perform sensing. Accordingly, the other Tx UE (s) will take into account the sensing results (e.g., the resource reservation and channel priority of the peer Tx UE forwarded by the peer Rx UE, as well as RSRP performance of the peer Rx UE) for the resource selection. This can avoid the collision with the peer Tx UE’s transmission and improve the performance by avoidance of the hidden node problem.

In Step 3. B-1, if the other UE (s) receiving the protecting SCI (s) is capable to know this SCI is for protecting purpose but not a legacy SCI, it performs sensing according to the decoded protecting SCI (s) , but it can ignore the first reserved resource occupied by this protecting SCI, because the peer Tx UE actually does not transmit signal on this resource.

In principle, the peer Rx UE can be deemed as an assisting UE which may assist the resource (re-) selection not only for the peer Tx UE but also for the other Tx UE (s) .

Additionally, the UE may perform sensing for resource (re-) selection based on the traffic type and/or resource reservation info by taking into account UE power consumption. If the traffic type is periodic traffic with known packet arrival time and/or the (periodic/aperiodic) resource has been reserved by SCI (and/or selected by UE but not reserved) , the UE should perform sensing before the reserved (and/or selected by UE) time and/or the traffic arrival time. If the traffic type is aperiodic traffic with unknown packet arrival time and/or the resource has not been reserved by SCI (and/or selected by UE) , the UE can perform sensing after the packet arrival. Moreover, the higher layer may indicate the traffic type or reservation type so that UE can know whether to perform prior sensing or post sensing.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more” . The word “exemplary” is used herein to mean “serving as an example, instance, or illustration” . Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C” , “one or more of A, B, or C” , “at least one of A, B, and C” , “one or more of A, B, and C” , and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C” , “one or more of A, B, or C” , “at least one of A, B, and C” , “one or more of A, B, and C” , and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module” , “mechanism” , “element” , “device” , and the like may not be a substitute for the word “means” . As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for” .

Claims

A methodperformed by a UE, comprising:

Reception ofSCI with reserved resource information and channel priority;

determining the reserved resources in SCI are preferred or not preferred based on the sensing results;

transmitting assistance information to the peer Tx UE and/or the other Tx UEs.