Reevaluating sidelink resources

Abstract

1. A method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication in a wireless communication network, the transmitting UE being configured to autonomously select resources for transmitting data received on a D2D communication link, the method including: selecting, by the transmitting UE, a first resource for transmitting data to be received on the D2D communication link from an associated user equipment; excluding, by the transmitting UE, the selected first resource based on at least one of: obtaining, by the transmitting UE, additional information indicating a contention with the first resource; receiving, by the transmitting UE, a control message from an associated UE including an updated resource; after the excluding, reselecting, by the transmitting UE, a second resource for transmitting the data to be received on the D2D communication link from the associated UE; and performing, by the transmitting UE, the transmission of the data using the second resource.

Description

[Technical Field]

[0001] The present disclosure relates generally to device-to-device (D2D) communication over sidelink (SL) resources, and more particularly to resource selection and allocation for sidelink transmissions. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP) specified support for Proximity Services (ProSe) in Long Term Evolution (LTE) in Release 12 (Rel-12) and Release 13 (Rel-13), which targeted public safety use cases (e.g., first responder) as well as a small subset of commercial use cases (e.g., discovery). The main novelty of ProSe was the introduction of device-to-device (D2D) communications using the Sidelink (SL) interface. During Release 14 (Rel-14) and Release 15 (Rel-15) in 3GPP, major changes were introduced to the LTE SL framework to support Vehicle-to-Everything (V2X) communications, where V2X collectively refers to communications between a vehicle and any other endpoint (e.g., vehicle, pedestrian, etc.). Its features mostly targeted basic V2X use cases, such as day-1 safety.

[0003] During Release 16 (Rel-16), 3GPP addressed the sidelink interface for fifth-generation (5G) New Radio (NR). The NR sidelink in Rel-16 targets advanced V2X services, which can be categorized into four use case (UC) groups: vehicle platooning, extended sensors, advanced driving, and remote driving. Supporting advanced V2X services required a new sidelink design to meet stringent requirements for latency and reliability. The NR sidelink in Rel-16 was designed to provide higher system capacity, increased reliability, and better coverage. Furthermore, the design considered the possibility of future extensions to support even more advanced V2X services and other related services.

[0004] The radio layer in LTE SL supported only broadcast communications. In contrast, NR SL includes support in the radio layer for broadcast, multicast, and unicast communications. For example, in platooning services, there are some messages that are important only to members of the platoon, which group the members of the platoon. In another example, known as a see-through use case, the most likely scenario involves only pairs of vehicles, for which unicast transmissions are a natural fit. As with LTE SL, NR SL is designed in a way that allows NR SL operation with and without network coverage, including support for standalone, network-less operation, and with different degrees of interaction between the user equipment (UE) and the network (NW).

[0005] 3GPP typically refers to D2D transmissions as sidelink transmissions, or transmissions using the PC5 interface. The applicable standards specify two resource allocation modes for the NR sidelink: network-based resource allocation and autonomous resource allocation.

[0006] In network-based resource allocation mode, the network selects the resources and other transmission parameters used by the sidelink UE. In some cases, the network may control all transmission parameters. In other cases, the network may select the resources used for transmission but give the transmitter freedom to select some of the transmission parameters, possibly with some restrictions. In the context of NR SL, 3GPP refers to this resource allocation mode as Mode 1.

[0007] In autonomous resource allocation mode, the UE autonomously selects resources and other transmission parameters. In this mode, there may be no network intervention (e.g., out of coverage, unlicensed carrier without network deployment, etc.) or very minimal network intervention (e.g., configuration of a pool of resources, etc.). In the context of NR SL, 3GPP refers to this resource allocation mode as Mode 2.

[0008] The network-based resource allocation mode (mode 1) and the autonomous resource allocation mode (mode 2) in NR are similar to mode 3 and mode 4 in LTE, respectively. Summary of the Invention

[0009] The present disclosure provides methods and apparatus for UE-to-UE coordination in resource selection for sidelink communications. One aspect of the present disclosure includes methods and apparatus for combining UE-to-UE coordination with additional sensing information to reduce the number of contentions and latency in D2D communications. The techniques herein describe combined resource utilization information (e.g., sensing information, grants, resource proposals, resource sets, etc.) collected by different nodes (e.g., UEs) and / or at different times. The techniques help resolve situations where resources selected using UE-to-UE coordination are later detected and reserved by another UE and reduce the probability of collisions in sidelink transmissions by reevaluating the resources to be used for the sidelink transmission.

[0010] In a first aspect of the present disclosure, there is provided a method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication in a wireless communication network, wherein the transmitting UE is configured to autonomously select resources for transmitting data received over a D2D communication link, the method including: selecting, by the transmitting UE, a first resource in a set of resources for transmitting data to be received over the D2D communication link from a coordinating user equipment; excluding, by the transmitting UE, the selected first resource based on at least one of: obtaining, by the transmitting UE, additional information indicating a conflict with the first resource; receiving, by the transmitting UE, a control message including the updated resource; after the excluding, reselecting / ignoring, by the transmitting UE, a second resource for transmitting the data to be received over the D2D communication link from the coordinating UE; and performing, by the transmitting UE, the transmission of the data using the second resource.

[0011] The inventors have found that in a UE-to-UE cooperation situation, a UE selecting resources for transmission, e.g., a transmitting UE, may miss information. For example, a UE-to-UE cooperation message may be generated by a cooperating UE without any sensing information being available at the transmitting UE. Another example is that a UE-to-UE cooperation message may be generated and transmitted by a cooperating UE before any additional sensing information is available.

[0012] In the cases described above, the resource selection made by the transmitting UE may not be suitable for transmission, i.e., it may suffer from an increased probability of collision or may be affected by half duplex.

[0013] In other situations, a transmitting UE in a UE-to-UE cooperation situation may end up having conflicting information. For example, the UE may be suggested to select a resource for which the UE later predicts a high likelihood of collision.

[0014] The inventors have discovered that situations may arise in which the selected resource may no longer be the desired resource for transmitting data, which may be determined, for example, by the transmitting UE obtaining additional information indicating a conflict with the first resource and / or by the transmitting UE receiving a control message from a cooperating UE that includes updated resources.

[0015] According to the present disclosure, the expression "associated" UE is used throughout this specification. It should be explicitly noted that an associated UE does not mean that the UE needs to have a higher hierarchy / privilege compared to other UEs. An associated UE can be any normal UE in a wireless communication network.

[0016] In one example, a transmitting UE may become aware of relevant information about future channel utilization, which may indicate a potential conflict with resources selected by the transmitting UE. The transmitting UE may then overrule the transmitting UE's selected resources and select alternative resources for transmission purposes.

[0017] In another example, a transmitting UE may select a first resource for transmission and may use a second resource for transmitting a reservation for the first resource. Based on this transmission, the transmitting UE may receive a control message from any other UE indicating a potential conflict with the first resource and / or a suggestion to use an alternative resource instead. Based on the received control message, the transmitting UE may ignore the first resource and select an alternative resource for transmitting data.

[0018] In yet another example, the cooperating UE may provide a first grant or a first proposal for resources to be used to transmit data to the transmitting UE. The cooperation may then obtain additional information that may be relevant to future channel utilization. For example, the additional information may indicate a potential conflict with the first grant or first proposal for resources. The cooperating UE may then decide to send another message to the transmitting UE with an updated grant or proposal for resources to be used to transmit the data. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 illustrates an exemplary communication network supporting D2D communication. [Figure 2] FIG. 1 is a diagram illustrating UE-to-UE cooperation. [Figure 3] FIG. 1 illustrates a first approach to UE cooperation between an associated UE (UE-A) and a transmitting UE (UE-B). [Figure 4] FIG. 10 is a diagram illustrating a second approach to UE-to-UE cooperation between an associated UE (UE-A) and a transmitting UE (UE-B). [Figure 5] FIG. 10 is a diagram illustrating a third approach to UE-to-UE cooperation between an associated UE (UE-A) and a transmitting UE (UE-B). [Figure 6] 1 illustrates a method implemented by a transmitting UE according to a first approach to inter-UE cooperation. [Figure 7] 10 illustrates a method implemented by a transmitting UE according to a second approach to UE-to-UE cooperation. [Figure 8] 10 illustrates a method implemented by a cooperating UE according to a second approach to inter-UE cooperation. [Figure 9] 10 illustrates a method implemented by a transmitting UE according to a third approach to UE cooperation. [Figure 10] 10 illustrates a method implemented by a cooperating UE according to a third approach to inter-UE cooperation. [Figure 11] FIG. 1 illustrates the main functional components of a UE configured for SL communication using UE-to-UE cooperation as described herein. DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring now to the drawings, UE-to-UE cooperation techniques according to the present disclosure will be described in the context of a wireless communication network implementing the NR communication standard. However, those skilled in the art will appreciate that the techniques are more generally applicable to any wireless communication network supporting D2D communication over a sidelink interface.

[0021] 1 illustrates a base station 20 that provides connectivity to a core network 40 for multiple UEs 30. While a single base station 20 is shown in FIG. 1, those skilled in the art will appreciate that a wireless communication network 10 will generally include many base stations 20. The base stations 20 may also be referred to in the NR standard as evolved node Bs (eNBs), 5G node Bs (gNBs), or next-generation eNBs (ng-eNBs).

[0022] UE-1 to UE-4 are capable of D2D communication with other UEs 30 in their vicinity over sidelinks (e.g., PC5 interfaces). UE-1, UE-3, and UE-4 are within network coverage, while UE-2 is outside network coverage. UE-1 is in the vicinity of UE-2 and UE-3 and can communicate with them over sidelinks SL1 and SL2, respectively. UE-2 is in the vicinity of UE-1 and UE-3 and can communicate with them over sidelinks SL1 and SL3, respectively. UE-3 is in the vicinity of UE-1, UE-2, and UE-4 and can communicate with them over sidelinks SL2, SL3, and SL4, respectively. Finally, UE-4 is in the vicinity of UE-3 and can communicate with them over sidelink SL4. However, UE-4 is out of range of UE-1 and UE-2 and cannot establish a direct connection with UE-1 or UE-2 over the sidelink. UE-4 can communicate with UE-1 through base station 20. However, UE-2 is out of coverage of base station 20.

[0023] One aspect of the present disclosure includes techniques for autonomous resource allocation for SL transmissions using UE-to-UE cooperation. The 3GPP standard defines two resource allocation modes for the NR sidelink: network-based resource allocation and autonomous resource allocation. In the network-based resource allocation mode, referred to as Mode 1, the network selects the resources and other transmission parameters used by the sidelink UE. In some cases, the network selects the resources used for transmission but may give the UE 30 the freedom to select some of the transmission parameters, possibly with some restrictions. In the autonomous resource allocation mode, referred to as Mode 2, the UE 30 autonomously selects the resources and other transmission parameters. In this mode, there may generally be no or very minimal network intervention (e.g., configuration of a pool of resources, etc.).

[0024] In SL transmission mode 2, distributed resource selection is adopted, i.e., there is no central node for scheduling, and resources are autonomously selected by UE 30. Transmission mode 2 is based on two functions: future resource reservation and sensing-based resource allocation. Future resource reservation is performed so that a UE 30 sending a message can inform a receiver about its intention to transmit using some time-frequency resources at a later time point. For example, a UE 30 transmitting at time T may inform a receiver that the UE 30 will transmit using the same frequency resources at time T+100 ms. Resource reservation allows a receiving UE 30 to predict radio resource utilization in the future. That is, by listening to the current transmission of another UE, the UE 30 also obtains information about potential future transmissions. This information can be used by the UE 30 to avoid collisions when selecting its own resources. In particular, the UE 30 predicts the future utilization of radio resources by reading received booking messages and then schedules its current transmission to avoid using the same resources. This is known as sensing-based resource selection.

[0025] In general, sensing can be described as monitoring slots in the sidelink resource pool from which resources are selected. Sensing can be performed over a defined window. The sensing-based resource selection scheme specified in NR Rel-16 can be roughly summarized in the following steps, which are specified in clause 8.1.4 of TS 38.214: The UE 30 senses the transmission medium during the interval [na,nb], where n is a time reference and a>b>0 defines the duration of the sensing window. The length of the sensing window is (pre)configurable. Sensing the transmission medium includes, among other things, receiving transmissions of control information indicating resource reservation and / or performing measurements. The UE 30 may in some cases exclude some time slots from the interval [na,nb] (e.g., slots in which the UE 30 transmits). Based on the sensing results, the UE 30 predicts the future utilization of the transmission medium in the future time interval [n+T1, n+T2], where T2>T1>0. The interval [n+T1, n+T2] is the resource selection window. The UE 30 selects one or more time-frequency resources among the resources in the selection window [n+T1, n+T2] that are predicted / determined to be selectable (e.g., idle, available, available, etc.).

[0026] The approaches to autonomous resource allocation described above aim to predict future channel utilization and select resources to avoid collisions. However, collisions may be detected after the initial allocation of resources. As an example, after selecting resources but before transmitting (i.e., before reserving any of the selected resources), UE 30 may detect, through detection, a potential collision affecting one of the selected resources. Note that the initial selection of resources made by UE 30 is an internal decision unknown to nearby UEs. At this point, the resources are said to be selected (but not reserved). After transmitting a reservation for the selected resource, surrounding UEs 30 become aware of this condition. At this point, the resource is considered reserved (or selected and reserved). As another example, after reserving a resource, UE 30 may detect a conflicting reservation transmitted by another UE 30. Which of the two reservations (if any) has priority can be determined by looking at the priority associated with each of those reservations. This information is signaled along with the reservation.

[0027] To avoid collisions in the previous two situations, two mechanisms are available: re-evaluation (or re-evaluation and re-selection) for when resources are selected but not reserved, and pre-emption (and re-selection) for when resources are selected and reserved.

[0028] In the case of re-evaluation, other UEs 30 may reserve the same resource(s) in the time lapse between the selection of the resource(s) and the transmission of the corresponding reservation. To avoid such conflicts, the UE 30 is enabled to reconsider its selection. The purpose of such a procedure is to evaluate whether the earlier selected resource(s) are still suitable for transmission. If the UE 30 determines that the earlier selected resource(s) are no longer suitable for its own transmission (e.g., some other UE 30 also selected the same resource(s) in the meantime), the UE 30 triggers the resource selection mechanism again. In this case, a new set of candidate resources is created, and the resource(s) is / are randomly selected from the newly created candidate resource set. This procedure is called re-evaluation, or re-evaluation and re-selection.

[0029] In preemption cases, after a reservation is sent, the UE 30 cannot reevaluate its selection. However, the UE 30 may be prevented from transmitting if another UE 30 has a higher priority transmission to perform. In these cases, known as preemption, the UE 30 (re)triggers resource selection if another UE 30 with a higher priority selects the same resources for its transmission. In this case, the UE 30 with a lower priority transmission (re)triggers resource selection, and a new set of candidate resource sets is created / determined by the UE 30 based on recent sensing information. This procedure is called preemption, or preemption and reselection.

[0030] In Release-17 (Rel-17), 3GPP is working on several enhancements for the sidelink (see RP-202846) to extend support for V2X and to cover other use cases (UCs), such as public safety. Improving performance for power-limited UEs 30 (e.g., pedestrian UEs, first responder UEs, etc.) and using resource coordination are considered two of the primary goals for this resource. One feature under consideration is inter-UE coordination. In one scenario under consideration, a first UE 30, denoted UE-A, determines a set of resources and sends the set of resources to UE-B. UE-B takes the resources indicated by UE-A into account in its resource selection for its own transmission. The information sent from UE-A to UE-B is called inter-coordination information.

[0031] Different approaches to inter-UE coordination are considered. In one approach, referred to as Scheme 1, the inter-UE information includes a set of preferred and / or non-preferred resources for UE-B's transmission. In another approach, referred to as Scheme 2, the coordination information sent from UE-A to UE-B includes the existence of expected / potential and / or detected resource contention for resources indicated by UE-B's sidelink control information (SCI). When UE-B receives inter-UE coordination information from UE-A, UE-B's selection or reselection of resources for its own transmission may be based on both UE-B's sensing results (if available) and the received coordination information, or may be based solely on the received coordination information. In some scenarios, the received coordination information is used for initial resource selection. In others, the received coordination information is used for resource reselection.

[0032] 2 shows an example of UE-to-UE cooperation. In this example, UE-A gathers some information through detecting transmissions by UE-1, UE-2, and UE-3. UE-A uses the information to provide UE-B with resources that may be suitable for its transmission. For example, the resources provided by UE-A can be used by UE-B to perform its own transmission.

[0033] When using UE-to-UE cooperation, the UE 30 (i.e., UE-B in the above example) selecting resources for transmission may miss some essential information. For example, a UE-to-UE cooperation message may be generated by UE-A without any sensing information being available at UE-B. Also, a UE-to-UE cooperation message may be generated and transmitted by UE-A before any additional sensing information is available. In these scenarios, the resource selection made by UE-B may not be suitable for transmission; that is, it may be subject to a high probability of collision or be affected by half duplex. In some scenarios, UE-to-UE cooperation may lead to conflicting information. For example, UE 30 may be suggested to select a resource for which UE 30 later predicts a high likelihood of collision.

[0034] One aspect of the present disclosure includes methods and apparatus for combining UE-to-UE cooperation with additional sensing information to reduce the number of contentions and latency in D2D communications. The techniques herein enable combining resource utilization information (e.g., sensing information, grants, etc.) collected by different nodes (e.g., UEs) and / or at different times. The techniques help resolve situations where resources selected using UE-to-UE cooperation are later detected and reserved by another UE 30 and reduce the probability of collisions in sidelink transmissions by reevaluating the resources to be used for the sidelink transmission.

[0035] A common theme of the methods described herein is that resources are selected (for themselves, granted to others, etc.) for data transmission using UE-to-UE cooperation. Later, new information regarding resource availability is collected. Based on the newly received and / or collected information, the suitability of the selected resources is reconsidered. Finally, new resources may be selected and others may be dropped. Different actions may be taken by different UEs.

[0036] The UE-to-UE coordination technique is described in the context of 3GPP sidelink, in which UEs 30 (operating any of the SL modes described earlier) communicate with each other directly without sending information through base station 20. However, the technique is more generally applicable to non-sidelink, as long as UE 30 obtains a grant (e.g., by itself, from another UE, a base station, etc.) and can determine, based on some information about the channel (e.g., collected through sensing, transmitted from another node, etc.), whether none of the resources can be used, some of the resources can be used, all of the resources can be used, or some other resources must be selected. In the following description, UE-A sends a UE-to-UE coordination message to UE-B, and UE-B selects resources for transmission.

[0037] In a first approach to UE-to-UE cooperation, a re-evaluation and pre-emption framework is used to reconsider the use of some resources previously granted to UE-B. In this approach, UE 30 is provided with first resources by a grant or other control message, and later, after acquiring more information about the channel or another grant, UE 30 drops the selected resources and selects second resources. Removing a selected resource may, for example, involve discarding a previous selection of resources if the resource was selected, or removing the resource(s) from the corresponding sidelink grant (which may be referred to as a selected sidelink grant). Figure 3 shows an embodiment of this approach, which includes the following steps: Step S1: UE-A sends a control message (e.g., a grant) including a first resource for data transmission to UE-B. UE-B receives the control message. Step S2: UE-B optionally selects a first resource. Step S3: UE-B obtains additional information relevant to future channel usage, which indicates potential conflicts with resources provided by control messages / grant. Step S4: UE-B discards (i.e. drops) the first resource indicated / granted in step S1 and selects / reselects a second resource for transmission. Step S5: UE-B performs transmission on the second resource selected in step S4.

[0038] Variations of step S1

[0039] In one embodiment, the control message from UE-A includes a grant. The grant may specify one or more resources for data transmission of UE-B. The resources may be listed in priority order.

[0040] In one embodiment, UE-B receives multiple control messages / grants, each from a different UE 30. Each of the UEs 30 providing a grant is referred to as UE-A in this context.

[0041] In one embodiment, UE-B determines resources that are common in all received control messages / grants. The resource determination can be for either available / preferred resources or unavailable / non-preferred resources.

[0042] In one embodiment, UE-B determines the resources that are common to the largest number of received control messages / grants. The resource determination can be for either available / preferred resources or unavailable / non-preferred resources.

[0043] In one embodiment, UE-B randomly selects among one of the received control messages / grants. In some cases, this may be conditional on the number or percentage of resources determined to be available, taking into account all received control messages / grants. The resource determination may be in terms of either available / preferred resources or unavailable / non-preferred resources.

[0044] In one embodiment, UE-B selects resources in the most recent of all received control messages / grants. In some cases, this may be conditional on the number or percentage of resources determined to be available given all received control messages / grants. The resource determination may be in terms of either available / preferred resources or unavailable / non-preferred resources.

[0045] In one embodiment, UE-B selects the control message / grant associated with the highest hierarchical / ranked UE, e.g., a roadside unit (RSU) node or a relay UE, among the received control messages / grant.

[0046] In one embodiment, UE-B selects, among the received control messages / grants, a control message / grant associated with UE-A to which a previous query from UE-B was sent, i.e., UE-B requested a control message / grant from a particular UE-A.

[0047] In one embodiment, the control message / grant is provided by a network node, such as a base station 20 (e.g., eNB, gNB, etc.).

[0048] A variant of S3.

[0049] In one embodiment, the additional information is obtained by the UE 30 through sensing.

[0050] In one embodiment, the additional information is obtained by the UE 30 from a control message / grant.

[0051] In one embodiment, obtaining the additional information includes performing measurements (eg, physical layer measurements).

[0052] In one embodiment, the additional information consists of a reservation transmitted by another UE, the reservation being for the same resources provided by the control message / grant in step S1. For example, the additional information may consist of control information transmitted by another UE 30 using physical layer (PHY) signaling (e.g., first stage SCI) or higher layer signaling (e.g., medium access control control element (MAC CE) or PC5 radio resource control (RRC) signaling).

[0053] In one embodiment, the first resource is a resource reserved by UE-B (e.g., UE-B has already sent a reservation for the resource). That is, between steps S2 and S3, UE-B reserves the granted resource. In this case, removing the reserved resource may be referred to as preemption.

[0054] In another embodiment, the first resource is a resource that is not reserved by UE-B (e.g., UE-B may have selected a resource but not (yet) reserved it by sending a reservation, or UE-B may have been granted a resource but not (yet) reserved it by sending a reservation). In this case, excluding the unreserved resource may be referred to as re-evaluation, or re-evaluation and re-selection.

[0055] In an embodiment, potential conflicts with resources provided by a control message / grant consist of collisions (ie, the same resources are reserved by another UE).

[0056] In an embodiment, potential conflicts with resources provided by control messages / grants consist of half-duplex situations (ie, two UEs 30 transmitting simultaneously while being destinations for each other's transmissions).

[0057] Variations of step S4

[0058] In one embodiment, UE-B performs a transmission in response to removing the resource. For example, UE-B may perform a transmission to indicate that UE-B is dropping the resource, or UE-B may perform a transmission to request more resources.

[0059] In one embodiment, UE-B selects new resources from a control message / grant provided by another UE 30 or a network node. The resources may be part of the control message / grant from step S1 or may be from another control message / grant (e.g., obtained in response to excluding resources).

[0060] In one embodiment, UE-B selects new resources from a control message / grant provided by the same UE 30 (ie, UE-A), but at a later point in time.

[0061] In one embodiment, UE-B selects new resources based on its own sensing information.

[0062] In one embodiment, UE-B selects new resources based on its own sensing information and UE-to-UE coordination messages received from other UEs.

[0063] In one embodiment, the UE discards the first resource selection and selects a second resource for data transmission.

[0064] In one embodiment, the UE removes the first resource from the selected grant and selects the second resource from the remaining resources.

[0065] In one embodiment, the UE notifies a higher layer protocol (e.g., radio resource control (RRC)) when the UE drops the first resource and / or reselects the second resource.

[0066] Variations of step S5

[0067] In one embodiment, the transmission includes control information that reserves further resources for (potential) transmissions in the future.

[0068] In a second approach to UE-A coordination, additional sensing capabilities at UE-A are used to provide UE-B with alternative resources for transmission whenever it is determined that UE-B's selection is affected by a potential collision. In this approach, UE 30 first selects a resource for its own transmission, and later, after receiving a UE-A coordination message, UE 30 discards or drops the selected resource and selects a second resource.

[0069] FIG. 4 illustrates an embodiment of this approach, which includes the following steps. Step S1: UE-B selects a first resource for transmission using a first mode of resource selection. Step S2: UE-B sends a reservation for a first resource. The reservation is received by UE-A. The reservation optionally includes an indication of the first mode of resource selection. Step S3: Based on the transmission received from UE-B, UE-A determines that the reserved resources are subject to a possible collision. Step S4: UE-A sends a control message (e.g., a grant) to UE-B. The control message / grant includes one or more resources for data transmission. UE-B receives the control message from UE-A. Step S5: UE-B discards (i.e. drops) the first selected resource and selects the second resource indicated in the control message / grant. Step S6: UE-B performs transmission on the second resource.

[0070] In one embodiment, the indication of the first mode of resource selection during reservation sent in step S2 includes an indication that the resource selection mode uses a reduced amount of sensing results. For example, the indication may indicate that the resources were randomly selected or used partial sensing information (e.g., used a reduced amount of sensing results).

[0071] In one embodiment, the control message in step S4 is a UE-to-UE coordination message, which may be sent using physical layer (PHY) signaling, MAC CE, RRC signaling, etc.

[0072] In one embodiment, the first mode of resource selection during the reservation sent in step S2 comprises full sensing based resource selection.

[0073] In one embodiment, the resources included in the control message (S4) are part of the control message / grant. In one embodiment, UE-B uses the resources provided in the control message / grant in the order provided in the control message / grant without the possibility of selecting other resources.

[0074] In one embodiment, the resources included in the control message / grant (S4) are a list of proposed resources, e.g., preferred / non-preferred resources. UE-B can choose which resources to use from those in the list (S4) or even select resources not in the provided list.

[0075] In a third approach to UE-UE coordination, the use of the reevaluation and preemption framework is extended to allow UE-A to reconsider resources provided to UE-B in an earlier UE-UE coordination message. This approach differs from the previous two approaches in that UE-A is responsible for granting resources to UE-B and for performing reevaluation and reselection and / or preemption.

[0076] FIG. 5 illustrates an embodiment of this approach, which includes the following steps. Steps S1 and S2: UE-A sends a first control message (e.g., a grant) to UE-B indicating a first resource for transmission. UE-B selects the first resource. Steps S3 and S4: UE-A obtains information relevant to future channel usage. Based on the additional information, UE-A determines potential conflicts with the first resource provided by the control message / grant. Step S5: UE-A provides a second control message / grant to UE-B indicating second resources for transmission. Step S6: Upon receiving the second control message / grant, UE-B discards the first resource and reselects the second resource. Step S7: UE-B transmits using the second resource.

[0077] Variations in steps S1 and S2.

[0078] In one embodiment, the first control message / grant includes potential resources for a second control message / grant from UE-A to UE-B.

[0079] Variations in steps S3 and S4.

[0080] In one embodiment, the information is obtained by the UE 30 through sensing.

[0081] In one embodiment, the information is obtained by the UE 30 in the form of a grant from another UE.

[0082] In one embodiment, the action performed in step S4 consists of using a re-evaluation mechanism. For example, UE-A may send a control message / grant for a first resource to UE-B in step S1. Prior to that resource, UE-A may detect a potential collision (using the rules for re-evaluation). This may trigger step S5.

[0083] In one embodiment, the operations performed in steps S3 and S4 consist of using a preemption mechanism. For example, in step S1, UE-A may send a control message / grant for a first resource and a third resource to UE-B. UE-B utilizes the third resource for the first transmission and reserves the first resource for a later transmission. After this, UE-A may detect a potential collision for the first resource (using the rules for preemption). This may trigger step S5.

[0084] In one embodiment, obtaining the information includes performing measurements (eg, physical layer measurements).

[0085] In one embodiment, the information consists of a reservation sent by another UE, the reservation being for the same resources provided by the control message / grant in step S1. For example, the information may consist of control information sent by another UE 30 using an SCI (e.g., first stage SCI) or higher layer signaling (e.g., MAC CE or PC5-RRC signaling).

[0086] General Considerations

[0087] An embodiment described for one approach in this disclosure may be applicable to other approaches in this disclosure. For example, Signaling used to carry control signaling (PHY, MAC CE, PC5-RRC). Control signaling, including UE-to-UE coordination messages. Detecting contention, including detecting potential collisions or potential half-duplex situations. Sensing, including measuring and / or receiving control information transmitted by others. Grant and / or proposed resource UE-to-UE interaction messages Whether the resources that will be dropped were already reserved, i.e., whether the resources will be preempted or just re-evaluated.

[0088] Different aspects of the method may be configured by a network node or may be part of a pre-configuration in the device (eg, in a subscriber identity module (SIM)).

[0089] 6 illustrates an example method 100 of UE-to-UE cooperation implemented by a transmitting UE 30 (UE-B in the above example). The transmitting UE 30 receives a control message from a cooperating UE 30 indicating one or more resources for data transmission and selects a first resource from among the one or more resources indicated by the control message (blocks 105 and 110). The transmitting UE 30 then obtains additional information indicating a conflict with the first resource (block 115). Based on the additional information, the transmitting UE 30 may optionally transmit control information to the cooperating UE 30 (block 120). The control information may, for example, indicate that the first resource has been dropped or may request a new resource for transmission. The transmitting UE 30 then reselects a second resource for data transmission and conducts the data transmission using the second resource (blocks 125, 130).

[0090] 7 shows an example method 150 of UE-to-UE cooperation implemented by a transmitting UE 30 (UE-B in the above example). The transmitting UE 30 selects first resources for data transmission and transmits a reservation of the first resources for the data transmission (blocks 155, 160). After transmitting the reservation, the transmitting UE 30 receives a control message from the cooperating UE 30 indicating one or more resources relevant for resource selection (block 165). In response to the control message, the transmitting UE 30 selects second resources for the data transmission and performs the data transmission using the second resources (blocks 170, 175).

[0091] In some embodiments, the control message indicates alternative resources for data transmission, and the transmitting UE 30 selects the second resource from among one or more alternative resources indicated by the control message. The alternative resources may overlap with resources indicated in the first control message or may represent all new resources. In other embodiments, the control message indicates non-preferred / non-allowable resources for data transmission, and the transmitting UE 30 selects resources not included in the control message. In this case, the transmitting UE 30 may select the resources indicated in the first control message as the second resource. The transmitting UE may also select resources in a control message from a different associated UE as the second resource.

[0092] 8 shows an example method 200 of UE-to-UE cooperation implemented by a cooperating UE 30 (UE-A in the example above). The cooperating UE 30 receives a reservation of a first resource for data transmission from a transmitting UE 30 (block 205). The cooperating UE 30 determines that there is a conflict with the first resource (block 210). In response to the determination, the cooperating UE 30 sends control information to the transmitting UE 30 indicating one or more resources relevant for resource selection (block 215).

[0093] In some embodiments, the control message indicates alternative resources for data transmission from which the transmitting UE 30 may select second resources for data transmission. The alternative resources may overlap with resources indicated in the first control message or may represent all new resources. In other embodiments, the control message indicates non-preferred / non-allowable resources for data transmission. In this case, the transmitting UE 30 may select the resources indicated in the first control message as the second resources. The transmitting UE may also select resources in a control message from a different associated UE as the second resources.

[0094] 9 illustrates an example method 225 of UE-to-UE cooperation implemented by a transmitting UE 30 (UE-B in the above example). The transmitting UE 30 receives a control message indicating one or more resources for data transmission and selects a first resource from the one or more resources indicated by the control message (blocks 230, 235). After selecting the first resource, the transmitting UE 30 receives a second control message indicating one or more alternative resources for data transmission (block 240). In response to the control message, the transmitting UE 30 reselects a second resource from the one or more alternative resources for data transmission and performs the data transmission using the second resource (blocks 245, 250).

[0095] 10 illustrates an example method 260 of UE-to-UE cooperation implemented by a cooperating UE 30 (UE-A in the example above). The cooperating UE 30 sends a first control message to a transmitting UE indicating one or more resources for data transmission (block 265). After sending the first control message, the cooperating UE 30 obtains additional information indicating a conflict with the first resource (block 270). In response to obtaining, the cooperating UE 30 sends a second control message to the transmitting UE 30 indicating one or more alternative resources for the data transmission (block 275). In some embodiments, the cooperating UE 30 then receives a data transmission from the transmitting UE 30 using the second resource selected from the alternative resources (block 280).

[0096] An apparatus may perform any of the methods described herein by implementing any functional means, module, unit, or circuit. In one embodiment, for example, an apparatus comprises a respective circuit or circuitry configured to perform the steps illustrated in a method diagram. The circuit or circuitry, in this regard, may comprise one or more microprocessors along with circuitry and / or memory dedicated to performing certain functional processing. For example, the circuitry may include one or more microprocessors or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), dedicated digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory, such as read-only memory (ROM), random access memory, cache memory, flash memory devices, optical storage devices, and the like. The program code stored in memory may, in some embodiments, include program instructions for executing one or more communication and / or data communication protocols, as well as instructions for performing one or more of the techniques described herein. In embodiments that employ memory, the memory stores program code that, when executed by one or more processors, performs the techniques described herein.

[0097] 11 illustrates a UE 300 according to another embodiment. The UE 300 comprises an antenna array 310 having one or more antennas 315, a communication circuit 320, a processing circuit 350, and a memory 360.

[0098] The communications circuitry 320 is coupled to the antenna 310 and includes radio frequency (RF) circuitry required to transmit and receive signals over a wireless communications channel. The RF circuitry may include, for example, a transmitter (TX) 330 and a receiver (RX) 340 configured to operate in accordance with the NR standard.

[0099] The processing circuitry 350 controls the overall operation of the UE 300 according to program instructions stored in memory 360. The processing circuitry 350 may comprise one or more microprocessors, hardware, firmware, or a combination thereof.

[0100] Memory 360 includes both volatile and nonvolatile memory for storing computer program code and data required by processing circuit 350 for operation. Memory 360 may include any tangible, non-transitory computer-readable storage medium for storing data, including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. Memory 360 stores a computer program 370 comprising executable instructions that configure processing circuit 350 to implement one or more of methods 100, 150, 200, 225, and 230 according to FIGS. 6-10, respectively. Computer program 370 may include one or more code modules corresponding to the means or units described above in this regard. Generally, computer program instructions and configuration information are stored in non-volatile memory, such as ROM, erasable programmable read-only memory (EPROM), or flash memory. Temporary data generated during operation may be stored in volatile memory, such as random access memory (RAM). In some embodiments, the computer program 370 for configuring the processing circuit 350 as described herein may be stored on a removable memory, such as a portable compact disc, a portable digital video disc, or other removable medium. The computer program 370 may also be embodied in a carrier, such as an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium.

[0101] Those skilled in the art will also appreciate that the embodiments herein further include corresponding computer programs comprising instructions that, when executed on at least one processor of the device, cause the device to perform any of the respective processes described above. The computer program may comprise one or more code modules corresponding to the means or units described above in this regard.

[0102] Embodiments further include a carrier containing such a computer program, which may comprise one of an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium.

[0103] In this regard, embodiments herein also include a computer program product comprising instructions stored on a non-transitory computer-readable (storage or recording) medium that, when executed by a processor of the device, cause the device to perform as described above.

[0104] Embodiments further include a computer program product, which may be stored on a computer-readable recording medium, comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a computing device.

[0105] The techniques described herein combine UE-to-UE coordination information with additional sensing information, which may have different origins or may be available at different times.

[0106] Embodiment 1. A method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication, the method comprising: receiving, from a coordinated UE, a control message indicating one or more resources for data transmission, the one or more resources including a first resource; selecting a first resource for data transmission; obtaining additional information indicating a conflict with the first resource; reselecting a second resource for data transmission; and performing data transmission using a second resource; A method comprising: 2. The method of embodiment 1, wherein the control message includes a set of resources, preferably a set of non-preferred or preferred resources. 3. The method of embodiment 1 or 2, wherein a transmitting UE receives control messages from multiple coordinated UEs and selects a resource indicated in one of the control messages. 4. The method of embodiment 3, wherein selecting a first resource includes selecting a resource that is common in all received control messages. 5. The method of embodiment 3, wherein selecting a first resource includes selecting a resource that is common to a maximum number of received control messages. 6. The method of embodiment 3, wherein selecting the first resource includes randomly selecting a resource in one of the received control messages. 7. The method of embodiment 3, wherein selecting a first resource includes selecting a resource indicated in the most recent of all received control messages. 8. The method of embodiment 3, wherein selecting the first resource includes selecting the resource based at least in part on a priority of the associated UE from which the control message was received. 9. The method of embodiment 3, wherein selecting the first resource includes selecting based at least in part on a previous request sent by the transmitting UE to one of the cooperating UEs. 10. A method according to any one of embodiments 1 to 9, wherein obtaining additional information indicating contention with the first resource includes obtaining the additional information by monitoring slots belonging to a sidelink resource pool. 11. The method of embodiment 10, wherein obtaining additional information indicating contention with the first resource includes performing measurements to obtain the additional information. 12. The method of any one of embodiments 1 to 10, wherein obtaining additional information indicating a conflict with the first resource includes receiving control information sent by another UE. 13. The method of embodiment 12, wherein the control information includes a set of resources, preferably a set of non-preferred or preferred resources. 14. The method of embodiment 12, wherein the control information includes a reservation. 15. The method of any preceding embodiment, wherein the first resource is a resource reserved by the transmitting UE. 16. The method of any one of embodiments 1 to 14, wherein the first resource is a resource that is not reserved by the transmitting UE. 17. The method of embodiment 1 or 16, further comprising reporting the reselection of the second resource to an upper layer protocol. 18. The method of any one of embodiments 1 to 17, wherein the additional information indicates a conflict with resources reserved by another transmitting UE. 19. The method of any one of embodiments 1 to 17, wherein the additional information indicates a half-duplex conflict. 20. The method of any one of embodiments 1 to 19, further comprising excluding the first resource after obtaining the additional information. 21. The method of embodiment 20, further comprising transmitting control information in response to excluding the first resource. 22. The method of embodiment 21, wherein the control information includes an indication that the transmitting UE has dropped the first resource. 23. The method of embodiment 21, wherein the control information includes a request for alternative resources to the coordinated UE. 24. The method of embodiment 23, wherein reselecting the second resource includes reselecting the second resource from alternative resources indicated in a control message received in response to the request. 25. The method of any one of embodiments 1 to 24, wherein reselecting the second resource includes reselecting the second resource from alternative resources indicated in a second control message received from a different UE than the first control message. 26. The method of any one of embodiments 1 to 24, wherein reselecting the second resource includes reselecting the second resource from alternative resources indicated in a second control message received at a different time point from the same coordinated UE as the first control message. 27. The method of any one of embodiments 1-22, wherein the transmitting UE reselects the second resource based on its own sensing information. 28. The method of any one of embodiments 1-22, wherein the transmitting UE reselects the second resource based on its own sensing information and a UE-to-UE coordination message received from another UE. 29. The method of any one of embodiments 1-28, wherein the data transmission includes a reservation for a future data transmission. 30. The method of any one of embodiments 1-29, wherein the control message includes one of physical layer signaling, medium access control control element (MAC-CE), or radio resource control (RRC) signaling. 31. A method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication, the method comprising: selecting a first resource for data transmission; transmitting a reservation message reserving a first resource for data transmission; receiving, after sending the reservation, a control message from the associated UE indicating one or more resources relevant for resource selection; selecting a second resource for data transmission in response to the control message; performing data transmission using a second resource; A method comprising: 32. The method of embodiment 31, wherein the reservation message further includes a mode indication indicating a first mode of resource selection for selecting the first resource. 33. The method of embodiment 32, wherein the mode indication includes an indication that the resource selection mode for selecting the first resource used a reduced amount of sensing results. 34. The method of embodiment 32, wherein the mode indication includes an indication that full sensing-based resource selection was used to select the first resource. 35. The method of any one of embodiments 31-34, wherein the control message includes one of physical layer signaling, medium access control control element (MAC-CE), or radio resource control (RRC) signaling. 36. The method of any one of embodiments 31 to 34, wherein the control message includes a set of resources, preferably a set of non-preferred or preferred resources. 37. The method of any one of embodiments 31 to 34, wherein the control message includes one or more alternative resources for data transmission, and the transmitting UE selects a second resource from the alternative resources indicated in the control message. 38. The method of any one of embodiments 31 to 34, wherein the control message includes one or more non-preferred or non-permitted resources, and the transmitting UE selects as the second resource a resource not indicated in the control message. 39. A method implemented by an associated user equipment (UE) configured for device-to-device (D2D) communication, the method comprising: receiving a reservation of first resources for data transmission from a transmitting UE; determining that there is a conflict with a first resource; sending control information to the transmitting UE in response to determining, the control information indicating one or more resources relevant for resource selection. A method comprising: 40. The method of embodiment 39, wherein the reservation includes a mode indication indicating a first mode of resource selection for selecting the first resource. 41. The method of embodiment 40, wherein the mode indication includes an indication that the resource selection mode for selecting the first resource used a reduced amount of sensing results. 42. The method of embodiment 39, wherein the mode indication includes an indication that full sensing-based resource selection was used to select the first resource. 43. The method of any one of embodiments 39-42, wherein the control message includes one of physical layer signaling, medium access control control element (MAC-CE), or radio resource control (RRC) signaling. 44. The method of any one of embodiments 39 to 42, wherein the control message includes a set of resources, preferably a set of non-preferred or preferred resources. 45. The method of any one of embodiments 39 to 44, wherein the control message includes one or more alternative resources for data transmission, and the transmitting UE selects a second resource from the alternative resources indicated in the control message. 46. ​​The method of any one of embodiments 39 to 45, wherein the control message includes one or more non-preferred or non-permitted resources, and the transmitting UE selects as the second resource a resource not indicated in the control message. 47. A method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication, the method comprising: receiving a control message indicating one or more resources for data transmission; selecting a first resource from among the one or more resources indicated by the control message; receiving a second control message indicating one or more alternative resources for data transmission after selecting the first resource; reselecting a second resource from the one or more alternative resources for data transmission; performing data transmission using a second resource; A method comprising: 48. The method of embodiment 47, wherein the second control message includes the resource indicated in the first control message. 49. A method implemented by an associated user equipment (UE) configured for device-to-device (D2D) communication, the method comprising: sending a first control message to a transmitting UE indicating one or more resources for data transmission; obtaining additional information indicating a conflict with a first resource among the one or more resources indicated by the first control message; in response to obtaining, sending a second control message to the transmitting UE indicating a second resource for data transmission; and A method comprising: 50. The method of embodiment 49, wherein the second control message includes the resource indicated in the first control message. 51. The method of embodiment 49 or 50, wherein the additional information is obtained by the cooperative UE through sensing. 52. The method of embodiment 49 or 50, wherein the additional information is obtained by the coordinated UE in a grant from another UE. 53. The method of embodiment 49 or 50, wherein the additional information is obtained by the cooperating UE during a reservation from another UE. 54. The method of embodiment 49 or 50, wherein obtaining the additional information includes performing physical layer measurements. 55. A transmitting user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: receiving, from a coordinated UE, a control message indicating one or more resources for data transmission, the one or more resources including a first resource; selecting a first resource for data transmission; obtaining additional information indicating a conflict with the first resource; reselecting a second resource for data transmission; and performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 56. A transmitting UE as described in embodiment 55, further configured to perform a method as described in any one of claims 2 to 30. 57. A transmitting user equipment (UE) configured for device-to-device (D2D) communications, the UE comprising: a communication circuit configured for sidelink communication with other UEs; Processing Circuit The processing circuitry comprises: receiving, from a coordinated UE, a control message indicating one or more resources for data transmission, the one or more resources including a first resource; selecting a first resource for data transmission; obtaining additional information indicating a conflict with the first resource; reselecting a second resource for data transmission; and performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 58. The transmitting UE of embodiment 57, wherein the processing circuitry is further configured to perform a method according to any one of claims 2 to 30. 59. A transmitting user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: selecting a first resource for data transmission; transmitting a reservation message reserving a first resource for data transmission; receiving, after sending the reservation, a control message from the associated UE indicating one or more resources relevant for resource selection; selecting a second resource for data transmission in response to the control message; performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 60. A transmitting UE as described in embodiment 59, further configured to perform a method as described in any one of claims 32 to 38. 61. A transmitting user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: a communication circuit configured for sidelink communication with other UEs; Processing Circuit and a processing circuit comprising: selecting a first resource for data transmission; transmitting a reservation message reserving a first resource for data transmission; receiving, after sending the reservation, a control message from the associated UE indicating one or more resources relevant for resource selection; selecting a second resource for data transmission in response to the control message; performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 62. The transmitting UE of embodiment 61, wherein the processing circuitry is further configured to perform a method according to any one of claims 32 to 38. 63. An associated user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: receiving a reservation of first resources for data transmission from a transmitting UE; determining that there is a conflict with a first resource; sending control information to the transmitting UE in response to determining, the control information indicating one or more resources relevant for resource selection. An associated user equipment (UE) configured to: 64. The cooperative UE of embodiment 63, further configured to perform the method of any one of claims 40 to 46. 65. An associated user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: a communication circuit configured for sidelink communication with other UEs; Processing Circuit The processing circuitry comprises: receiving a reservation of first resources for data transmission from a transmitting UE; determining that there is a conflict with a first resource; sending control information to the transmitting UE in response to determining, the control information indicating one or more resources relevant for resource selection. An associated user equipment (UE) configured to: 66. The cooperative UE of embodiment 65, wherein the processing circuitry is further configured to perform a method according to any one of claims 40 to 46. 67. A transmitting user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: receiving a control message indicating one or more resources for data transmission; selecting a first resource from among the one or more resources indicated by the control message; receiving a second control message indicating one or more alternative resources for data transmission after selecting the first resource; reselecting a second resource from the one or more alternative resources for data transmission; performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 68. A transmitting UE as described in embodiment 67, further configured to perform the method of claim 48. 69. A transmitting user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: a communication circuit configured for sidelink communication with other UEs; Processing Circuit and a processing circuit comprising: receiving a control message indicating one or more resources for data transmission; selecting a first resource from among the one or more resources indicated by the control message; receiving a second control message indicating one or more alternative resources for data transmission after selecting the first resource; reselecting a second resource from the one or more alternative resources for data transmission; performing data transmission using a second resource; a transmitting user equipment (UE) configured to: 70. The transmitting UE of embodiment 69, wherein the processing circuitry is further configured to perform the method of claim 48. 71. An associated user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: sending a first control message to a transmitting UE indicating one or more resources for data transmission; obtaining additional information indicating a conflict with a first resource among the one or more resources indicated by the first control message; in response to obtaining, sending a second control message to the transmitting UE indicating a second resource for data transmission; and An associated user equipment (UE) configured to: 72. The cooperative UE of embodiment 71, further configured to perform the method of any one of claims 50 to 54. 73. An associated user equipment (UE) configured for device-to-device (D2D) communication, the UE comprising: a communication circuit configured for sidelink communication with other UEs; Processing Circuit and a processing circuit comprising: sending a first control message to a transmitting UE indicating one or more resources for data transmission; obtaining additional information indicating a conflict with a first resource among the one or more resources indicated by the first control message; in response to obtaining, sending a second control message to the transmitting UE indicating a second resource for data transmission; and An associated user equipment (UE) configured to: 74. The cooperative UE of embodiment 73, wherein the processing circuitry is further configured to perform a method according to any one of claims 50 to 54. 75. A computer program comprising executable instructions that, when executed by processing circuitry in user equipment in a wireless communications network, cause the user equipment to perform a method according to any one of claims 1 to 54. 76. A carrier containing the computer program of claim 75, the carrier being one of an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium.

Claims

1. 1. A method implemented by a transmitting user equipment (UE) configured for device-to-device (D2D) communication in a wireless communication network, the transmitting UE being configured to autonomously select resources for transmitting data received on a D2D communication link, the method comprising: receiving, by the transmitting UE, a plurality of control messages from each of a plurality of different coordinated UEs indicating one or more non-preferred or non-allowed resources for transmitting the data; selecting, by the transmitting UE, first resources for transmitting data to be received over the D2D communication link from a cooperating UE; a first resource selected by the transmitting UE, obtaining, by the transmitting UE, additional information indicating contention with the first resource; receiving, by the transmitting UE, a control message from the associated UE indicating updated resources; excluding based on at least one of: reselecting, by the transmitting UE after the excluding, second resources for transmitting the data to be received over the D2D communication link from the cooperating UE; performing, by the transmitting UE, the transmission of the data using the second resource. Including, The method, wherein the step of selecting the first resource includes selecting the first resource from one or more resources that do not include a resource that is commonly indicated in a maximum number of control messages among the plurality of received control messages.

2. The method of claim 1 , wherein receiving the control message from the cooperating UE is triggered by a request received from the transmitting UE or is performed autonomously by the cooperating UE.

3. 2. The method of claim 1, wherein the obtaining additional information indicating the contention with the first resource comprises obtaining the additional information by monitoring slots belonging to a sidelink resource pool.

4. obtaining additional information indicating the contention with the first resource; performing measurements to obtain said additional information; receiving control information transmitted by another UE in said wireless communication network; The method of claim 3, comprising any one of:

5. The method of claim 4 , wherein the control information is one of a grant and a reservation.

6. The method of claim 1 , wherein the first resource is a resource reserved by the transmitting UE.

7. The method of claim 1 , wherein the method comprises reporting the reselection of the second resource to a higher layer protocol.

8. The additional information is a collision with resources reserved by another transmitting UE in the wireless communication network; - Half-duplex contention The method of claim 1 , wherein the method instructs either

9. The method comprises: transmitting, by the transmitting UE, control information in response to excluding the first resource. The method of claim 1 comprising the steps of:

10. the control information responsive to excluding the first resource: an indication that the transmitting UE has excluded the first resource; Requesting alternative resources from the associated UE 10. The method of claim 9, comprising any one of:

11. 11. The method of claim 10, wherein the reselecting step includes reselecting the second resource from alternative resources indicated in a control message received in response to the request for an alternative resource.

12. The transmitting UE: - its own detection information, its own sensing information in combination with UE-to-UE coordination messages received from other UEs; The method of claim 1 , wherein the second resource is reselected based on one of:

13. 10. The method of claim 1, wherein the control message comprises one of physical layer signaling, medium access control control element (MAC-CE), or radio resource control (RRC) signaling.

14. The method comprises: transmitting, prior to the excluding step, a reservation message by the transmitting UE reserving the first resources for transmitting data to be received on the D2D communication link. including the steps The step of obtaining additional information comprises: receiving, by the transmitting UE, a control message from a cooperating UE indicating one or more resources relevant for resource selection; The method of claim 1 , comprising:

15. The method of claim 14 , wherein the reservation message further includes a mode indication indicating a first mode of resource selection for selecting the first resource.

16. The mode instruction is an indication that a resource selection mode for selecting the first resource used a reduced amount of sensing results or no sensing results; an indication that full detection-based resource selection was used to select the first resource; 16. The method of claim 15, comprising any one of:

17. 14. The method of claim 13, wherein the control message includes one or more alternative resources for transmission of the data, and the transmitting UE selects the second resource from the alternative resources indicated in the control message.

18. The method of claim 13 , wherein the transmitting UE selects as the second resource a resource not indicated in the control message.

19. 19. A transmitting user equipment (UE) configured for device-to-device (D2D) communication in a wireless communication network, wherein the transmitting UE is configured to autonomously select resources for transmitting data received on a D2D communication link, and wherein the transmitting UE is configured to perform a method according to any one of claims 1 to 18.

20. 19. A computer program comprising executable instructions that, when executed by processing circuitry in a user equipment (UE) in a wireless communication network, cause the UE to perform the method of any one of claims 1 to 18.

21. 1. A vehicle comprising a user equipment (UE) configured to operate in a wireless communication network, the vehicle comprising: a processing circuit configured to implement the method according to any one of claims 1 to 18, - a power supply circuit arranged to supply power to said processing circuit; A vehicle equipped with:

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