Channel access mechanism in wireless communication

Abstract

A method for selecting sidelink radio resources by a user equipment (UE) includes transmitting on the selected radio resources from the UE to one or more receivers; determining whether the UE successfully transmitted on the selected radio resources; identifying the selected radio resources as preferred radio resources based on a determination that the UE successfully transmitted on the selected radio resources; and prioritizing transmission on the preferred radio resources at a next transmission opportunity by the UE.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED PATENT APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 371,039, filed August 10, 2022, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to channel access mechanisms in wireless communications, and in particular to selecting sidelink radio resources by user equipment for transmission. [Background technology]

[0003] Sidelink communication is used in the 3GPP air interface to allow two (or more) user equipments (UEs) (e.g., wireless devices) to communicate directly with each other. This can occur under the coverage of a cellular network, outside the coverage of a cellular network, or within partial coverage of a cellular network where only one of the two UEs is under the coverage of the cellular network. In the 3GPP example, device-to-device direct communication uses the PC5 interface. Summary of the Invention

[0004] In some embodiments, a method for selecting sidelink radio resources by a user equipment (UE) is provided, the method including transmitting on the selected radio resources from the UE to one or more receivers, determining whether the UE successfully transmitted on the selected radio resources, identifying the selected radio resources as preferred radio resources based on a determination that the UE successfully transmitted on the selected radio resources, and prioritizing transmission on the preferred radio resources at a next transmission opportunity by the UE.

[0005] In some embodiments, a user equipment (UE) for selecting sidelink radio resources is provided. The UE includes: a memory configured to store instructions; and a processor configured to execute the instructions stored in the memory. The processor is configured to: transmit on the selected radio resources from the UE to one or more receivers; determine whether the UE successfully transmitted on the selected radio resources; identify the selected radio resources as preferred radio resources based on a determination that the UE successfully transmitted on the selected radio resources; and prioritize transmission on the preferred radio resources at a next transmission opportunity by the UE.

[0006] In some embodiments, a non-transitory computer-readable medium storing instructions executable by one or more processors of user equipment (UE) in a communications network to perform a method is provided, the method including transmitting on selected radio resources from the UE to one or more receivers, determining whether the UE successfully transmitted on the selected radio resources, identifying the selected radio resources as preferred radio resources based on a determination that the UE successfully transmitted on the selected radio resources, and prioritizing transmission on the preferred radio resources at a next transmission opportunity by the UE.

[0007] These and other aspects and their implementations are explained in more detail in the following description and drawings. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart of a method for selecting sidelink radio resources by a user equipment (UE), consistent with certain embodiments of the present disclosure. [Figure 2] 1 is a block diagram of a UE consistent with certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the drawings. The following description refers to the accompanying drawings, in which, unless otherwise indicated, like numerals represent the same or similar elements in different drawings. The implementations described in the following description of exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of apparatus, systems, and methods consistent with aspects related to the subject matter that may be recited in the appended claims.

[0010] Generally described, one or more aspects of the present disclosure relate to autonomous sensing or reservation of radio resources. Some embodiments described herein may be applied to 3GPP sidelink solutions, such as 3GPP 5G NR-V2X PC5 Mode 2 or 3GPP LTE-V2X PC5 Mode 4.

[0011] Sidelink and Detection

[0012] Resources are defined in terms of time and frequency. Regarding resource (re)selection mechanisms for SL, where the UE autonomously allocates resources, sensing-based resource selection can perform resource exclusion based on sensing information, followed by resource selection from the remaining candidate resources, including randomness. Alternatively, the UE can perform resource selection based on randomness without sensing (referred to as "random resource selection"). Release 14 / 15 LTE SL and Release 16 / 17 NR SL already support both options. Sensing-based resource selection enables reliable communication by avoiding resource collisions as much as possible, but its power consumption and complexity are higher than random resource selection due to sensing operations. Random resource selection is more suitable for battery-limited devices because sensing operations are not required but resource collisions may increase. Generally, channel access latency is not an issue with sensing-based resource selection because sensing can be performed continuously in the background. The channel access latency of both solutions can be controlled by the packet delay budget parameter.

[0013] Listen-Before-Talk (LBT) detection is supported in 3GPP NR (New Radio) and unlicensed spectrum (e.g., Release 13) in unlicensed spectrum (NR-U). It is used for potential radio transmitters in LTE (Licensed Assisted Access for Long Term Evolution).

[0014] The idea of ​​LBT sensing in NR-U and LTE Licensed Assisted Access (LAA) is that a potential transmitter senses the channel before transmitting. If the channel is deemed "busy" (e.g., by determining a received energy detection threshold for a specified duration), the potential transmitter will not transmit. If the channel is deemed "free" (e.g., received energy is below a threshold), the transmitter will transmit later as specified in the standard.

[0015] In 3GPP, there are two types of LBT techniques. The first is a "load-based device" approach, in which a potential transmitter senses the channel when it needs to transmit (several deferral periods are possible). The second is a "frame-based device" approach, in which a potential transmitter senses the channel at a fixed time instant. These LBT mechanisms Some (especially load-based) devices include some kind of "time randomness" and "backoff" to give different UEs a fair chance to access the channel and avoid continuous collisions that block the channel. For example, some random "backoff" period can be used before transmission.

[0016] To provide other UEs (i.e., UEs other than the UE that accessed the channel) with some opportunity to access the channel, 3GPP technical specifications provide a "channel occupation time" that defines the total duration during which an eNB / gNB / UE and any eNB / gNB / UE sharing the channel occupation transmit on the channel after the eNB / gNB / UE has performed the corresponding channel access procedure. To determine the channel occupation time, if the transmission gap is 25 μs or less, the gap duration is counted in the channel occupation time. The channel occupation time can be shared for transmission between the eNB / gNB and the corresponding UE. After this period expires, a new sensing is required.

[0017] In LTE and NR sidelink, sensing is performed to collect resource reservation information from other UEs and measure SL-RSRP (Sidelink Reference Signal Received Power) and SL-RSSI (Sidelink Received Signal Strength Indicator) to enable the transmitting UE to determine the available resources within the selection window.

[0018] Random selection of radio resources (e.g., from a set of available radio resources) requires that the proportion of radio resources required by all UEs is small compared to the total available radio resources, otherwise resource collisions will occur between different UEs, resulting in poor performance and fewer UEs being able to communicate (or not).

[0019] To attempt to favor some UEs relative to other UEs in different priority classes, different priority classes resulting in different "backoff" periods and different channel occupancy times are allowed in NR-U Release 16. However, this does not change the "random" nature of initial channel access (especially for UEs within a particular priority class).

[0020] For NR sidelink Release 16, the UE can perform its radio resource (re)selection based on detection (for resource allocation mode 2) within a resource pool. The resource pool, provided to the UE by configuration or pre-configuration (e.g., with or without a SIM (Subscriber Identity Module) / USIM (Universal Subscriber Identity Module)), is defined in the frequency domain in terms of subchannels and in the time domain in terms of slots or subframes. The selected frequency resource may be used multiple times at fixed time intervals for subsequent transmissions (this scheme is called semi-persistent scheduling (SPS)) or only once (this scheme is called one-shot transmission (OST)). The UE can also retransmit a packet multiple times with or without feedback from one or more receiver UEs to increase reliability (this is called hybrid automatic repeat request or HARQ retransmission).

[0021] Additionally, the transmitter UE may perform resource reservation announcements for the next transport block transmission and for retransmissions of the current transport block to inform other UEs about the resources selected by the transmitter UE for future sidelink transmissions (so that other UEs avoid those resources). This information is provided to other UEs by the "first stage sidelink control information (SCI)" provided by the physical sidelink control channel (PSCCH). The term "first stage" is used because this "first stage SCI" is used to demodulate / detect another physical channel, namely the physical sidelink shared channel (PSSCH) that carries sidelink data. This is because the second stage SCI also contains information to be used and also contains the "second stage SCI" used for control signaling. However, with all this, the transmitter UE autonomously selects some free available resources with some (uniformly distributed) random component. Additionally, this does not change the collision problem that may result from the random component of the resource (re)selection.

[0022] In NR-U Release 16, after initiating a transmission following initial sensing (Type 1), channel access Type 2 (including Type 2A, 2B, or 2C) may be used. This involves sending several additional transmissions almost immediately after the first transmission. Depending on the size of the gap between two transmissions, Procedure 2A, 2B, or 2C may be used. Procedures 2A or 2B require sensing, while Procedure 2C does not. This does not solve the above problem, as they represent a "short" transmission of additional data within the channel occupation time (COT), after which the "Type 1" channel access procedure begins again.

[0023] For 3GPP LTE V2X PC5 Mode 4, the UE selects radio resources based on detection and transmits based on SPS and OST, similar to Release 16 NR-V2X PC5 Mode 2. In addition, the UE can select and reserve resources based on detection and geographical zone (e.g., as defined in 3GPP TR 37.985), and the UE transmits within the resource pool associated with its current zone, which is used for resource reservation after detection. Detection and resource selection still suffer from the issues mentioned above (i.e., possible collisions with other UEs using the same resource pool).

[0024] Previous successful use of resources by the UE

[0025] One solution to the above problem is for the UE to use some previously successful resources instead of some random resources during or after performing sensing and / or resource (re)selection. Previously successful resources may be defined to include resources that have previously led to successful transmissions. For example, resources that resulted in a free channel, the absence of collisions following transmission after sensing a free channel, and / or previous successful reception by one or more receivers. The absence of collisions following transmission after sensing a free channel may be determined by use of a timer (which may be pre-configured). A reply (possibly including an explicit positive reply) from the receiver (possibly within a predetermined time) may be determined to be a "success."

[0026] For the time dimension of those resources, some time slots (or sub-time slots) may be defined as a reference. A UE performing initial detection may use the same time slot (or sub-time slot) number as a previously successful time slot. The time slot numbering may be defined using a synchronization reference.

[0027] For example, if resource selection in one transmission opportunity is successful, in the sense that the receiver acknowledges successful reception of the data, there was no collision. In that case, it may be advantageous to reuse the same resource for subsequent transmission opportunities, on the rationale that the same resource in the next and subsequent transmission opportunities may have a higher probability of success than a completely random and independent selection from a uniform distribution of resources.

[0028] In some implementations, the selected resource may be used multiple times at fixed time intervals for subsequent transmissions in a scheme called semi-persistent scheduling (SPS), or may be used only once in a scheme called one-shot transmission (OST). The difference between this and existing SPS schemes is that a transmitting UE will reuse a resource only if that resource has been reused successfully before. The advantage of the successful resource reuse approach is that it can mitigate persistent packet loss issues in SPS due to resource collisions, half-duplex, and / or near-far problems. SPS is currently supported in Release 16 / 17 NR. In SL, both detection-based and random resource selection are supported.

[0029] The previously successful resource can be defined under various possible embodiments, including the following:

[0030] The resources that have been successfully sensed (in terms of time and / or frequency), for example using a clear channel determination or using a non-collision check and / or receiving a response from the receiver.

[0031] The resources (in terms of time and / or frequency) on which the MAC (Medium Access Control) was successfully received.

[0032] Resources that have successfully received PDCP (Packet Data Convergence Protocol).

[0033] A resource that successfully received an IP (Internet Protocol) packet.

[0034] A resource that successfully receives an RLC (Radio Link Control) SDU (Service Data Unit) / PDU (Protocol Data Unit).

[0035] A resource that has successfully connected and / or received at the physical layer.

[0036] PC5-RRC (Radio Resource Control) resources successfully connected and / or received.

[0037] As used herein, the term "success" may be defined to include one or more successes as defined above. In some disclosed embodiments, a "success" may include one previous success or N previous successes, where N is an integer greater than 1.

[0038] Previously successful resources may also be referred to as "preferred resources." In the above process, preferred resources may be used to modify detection. For example, instead of the UE randomly selecting from among available resources (i.e., with uniformly distributed probability), preferred resources may be associated with a higher probability (e.g., twice as high) than non-preferred resources. The distribution rule may be defined in a standard, provided to the UE by network configuration, e.g., by radio resource control (RRC) signaling, and / or provided to the UE by pre-configuration. As another example, preferred resources may be used to bypass initial detection, i.e., the preferred resources may be used as the initial resource configuration.

[0039] 1 is a flowchart of a method 100 for selecting sidelink radio resources by a user equipment (UE), consistent with certain embodiments of the present disclosure. Radio resources are selected by the UE, and the UE transmits to one or more receivers on the selected radio resources (step 102). It is determined whether the UE successfully transmits on the selected radio resources (step 104). The term "successfully transmits" is defined elsewhere in this disclosure, and examples of what constitutes a successful transmission are described below. If the UE does not successfully transmit on the selected radio resources (step 104, "NO" branch), the UE , selects a radio resource (step 106), and method 100 returns to step 102 to attempt transmission on the other selected radio resource. In some embodiments, the radio resource is another radio resource that is different from the selected radio resource used in step 104. In other embodiments, if the UE is unsuccessful in transmitting on the selected radio resource (step 104, "NO" branch), the UE selects a radio resource that is different or the same as the previously selected radio resource (step 106), e.g., the previously selected radio resource is added to a pool of potential radio resources from which a radio resource may be selected each time step 106 is performed.

[0040] If the UE successfully transmits on the selected radio resource (step 106, "YES" branch), the selected radio resource is identified as a preferred radio resource (step 108). In some embodiments, an identifier of the preferred radio resource may be stored (step 110). Note that storing the identifier of the preferred radio resource is optional, as indicated by the dashed outline of step 110 in FIG. 1. For example, the identifier may be stored in a memory of the UE. The identifier may take the form of a subcarrier, PRB, or subchannel in the frequency domain, and a symbol, slot, or subframe in the time domain. At the next transmission opportunity, the UE prioritizes transmission on the preferred radio resource (step 112).

[0041] In some embodiments, the method 100 includes selecting a radio resource from a resource pool as the selected radio resource. The resource pool may be provided to the UE by configuration or pre-configuration.

[0042] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource includes determining whether the selected radio resource is available after sensing on one or more radio resources.

[0043] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource includes determining the absence of a collision on the selected radio resource during the transmission, which may be determined based on the absence of a collision being detected within a predetermined period of time after the transmission.

[0044] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource is determined based on responses received from one or more receivers within a predetermined period of time after the transmission.

[0045] In some embodiments, determining whether the UE has successfully transmitted on the selected radio resource includes determining that there has been a previous successful reception by one or more receivers from the UE on the selected radio resource.

[0046] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource includes determining that an acknowledgment of the hybrid automatic repeat request for the transmission was received.

[0047] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource includes determining that a hybrid automatic repeat request negative acknowledgment is not received for the transmission within a predetermined period of time.

[0048] In some embodiments, determining whether the UE has successfully transmitted on the selected radio resource may include determining whether the transmission is successful based on one of the following: determining that the received radio link control data unit segment has resulted in any one of: link control reception, successful reception of a radio link control service data unit segment, successful reception of a radio link control protocol data unit, successful reception of a medium access control packet, acknowledgement of a predetermined number of hybrid automatic repeat requests, acknowledgement of a predetermined number of hybrid automatic repeat requests within a predetermined period of time, successful reception of an Internet Protocol packet, a successful physical layer connection, or successful physical layer reception, which may be, for example, on a physical uplink control channel or a physical sidelink shared channel.

[0049] In some embodiments, determining whether the UE has successfully transmitted is based on using random resource selection, where a preferred radio resource may have a higher probability than one or more other radio resources.

[0050] In some embodiments, identifying the selected radio resource as a preferred radio resource includes identifying the selected radio resource as a preferred radio resource after a predetermined number of successful transmissions using the selected radio resource or after a predetermined number of successful transmissions using the selected radio resource within a predetermined time period.

[0051] In some embodiments, the method 100 further includes selecting a preferred radio resource based on sensing on one or more radio resources, and transmitting on the preferred radio resource.

[0052] In some embodiments, the preferred resources apply to a UE that successfully transmits the first burst (e.g., radio frame) in a communication exchange. A successfully transmitting UE may also be referred to herein as a transmitter UE or a transmitting UE.

[0053] In another embodiment, a receiver UE that successfully communicates with the transmitter UE while not triggering an initial burst can consider this initial resource as unauthorized (and / or deprioritized, e.g., by having a lower distribution probability), and therefore remains "reserved" for the transmitter UE. The reverse is also possible, i.e., the initial transmitter UE deprioritizes resources and the initial receiver UE prioritizes resources.

[0054] In another embodiment, the transmitter UE determines the preferred and non-preferred resources at the sub-channel level (set of resource blocks) or resource block level in the frequency domain.

[0055] In another embodiment, the transmitter UE uses different probabilities depending on the packet priority. The probabilities for different packet priorities may be configured or pre-configured, defined by the 3GPP specifications, or up to the implementation or higher layers. The "priority" referred to here may be a priority class (currently 1-4) or other priorities, such as ProSe Per-Packet Priority (PPPP), logical channel priority, and / or quality of service priority.

[0056] In another embodiment, the transmitter UE uses different probabilities depending on its radio access capability or radio access technology (e.g., LTE or NR) and / or depending on the radio access capability effectively used for access.

[0057] In other embodiments, any of the above concepts may be used for resource selection following initial sensing (instead of, or in addition to, initial sensing).

[0058] In other embodiments, any of the above concepts may be used for resource selection without using early detection.

[0059] In other embodiments, any of the above concepts can be used to bypass potential detection, for example by assigning a probability of "1" to some resources.

[0060] Providing information from UE to other UE

[0061] In another embodiment, a transmitting UE that has previously successfully transmitted, received, or communicated may transmit to other UEs (unicast, groupcast, or broadcast) an identification of the channel (time and / or frequency) on which the transmitting UE's initial transmission was successful. The other UEs may interpret this information as resources reserved by the transmitting UE and refrain from using the reserved resources for initial access. For example, this information may be provided as part of the "first phase SCI" described above. As another example, this information may be provided as a sidelink UE-to-UE communication or message.

[0062] Early detection using zone information

[0063] In another embodiment, the UE can use geographic location or zone information for initial sensing related to initial access. This information can define the set of time and / or frequency resources used for initial sensing. Using this information can help avoid situations where two nearby UEs attempt to use similar resources.

[0064] Any of the above options may be configured by RRC signaling or may be pre-configured in the UE.

[0065] Resources that resulted in successful Packet Data Convergence Protocol (PDCP) reception

[0066] In a 5G NR example, successful PDCP reception may depend on successful reception as defined in 3GPP TS 38.323, the NR PDCP protocol. For a transmitter UE, successful reception may include successful delivery of the PDCP SDU, which may be confirmed by a received PDCP status report. For a receiver UE, successful reception may include sending a PDCP status report reporting successful delivery (i.e., reception by the transmitter UE) of the PDCP SDU.

[0067] It is noted that the status report may rely on the existing status report from 3GPP TS 38.323, which uses PDCP control PDUs to carry the PDCP status report. Any of the existing fields in the PDCP status report may be used to further distinguish the condition (i.e., the condition is not just that a PDU is received). The condition may be more selective. In an example relying on the D / C (Data / Control) field, it may indicate that a data PDU has been received relative to a control PDU. For example, the D / C field may indicate a control PDU with a "0" in the D / C field or a data PDU with a "1" in the D / C field. Other fields in the status report may also be used. For example, a bitmap field may be used to indicate which SDUs are missing and which SDUs were correctly received by the receiving PDCP entity.

[0068] In another embodiment, if at least one PDCP SDU is received correctly, at least one PDCP SDU is received correctly while no PDCP SDUs are missing. A reception may be determined to be successful if the number of correctly received PDCP SDUs is greater than the number of missing PDCP SDUs. The comparison of the number of SDUs with the number of missing PDCP SDUs may be performed by ratio or may be provided to the UE by configuration, e.g., RRC configuration or pre-configuration. In other embodiments, successful reception may be determined if the number of correctly received PDCP SDUs is greater than or equal to a threshold and / or if the number of missing PDCP SDUs is less than or equal to a threshold. These thresholds may be defined, e.g., in 3GPP TS 38.323, configured in the UE by a higher layer, e.g., RRC, or pre-configured in the UE. Any combination of the above conditions for determining successful reception is possible.

[0069] In another embodiment, the status report in subclause 6.2.3.1 from 3GPP TS 38.323 may be reused with new fields added. For example, determining the condition may be performed at the transmitter of the status report rather than at the receiver of the status report. As an example, a new field such as "received successfully" may be defined.

[0070] [Table 1]

[0071] The specific transmission of the PDCP status report may be triggered in addition to the currently existing triggers for sending a PDCP status report in 3GPP TS 38.323 (PDCP entity re-establishment, PDCP data recovery, uplink data switch, or PDCP entity reconfiguration requested by higher layers). This additional trigger may be, for example, the correct reception of the first PDCP PDU and / or SDU, or the correct reception of several PDCP PDUs and / or SDUs. More generally, the condition for triggering sending a status report may reuse any of the embodiments or conditions described above. Note that the two conditions may be different in one embodiment if a specific new trigger for sending a PDCP status report is used and new fields are defined in the status report. In another embodiment, the conditions may be the same (i.e., the condition for triggering sending a PDCP status report may reflect information provided by some of the fields).

[0072] In the case of a transmitter, successful delivery of a PDCP data PDU is acknowledged by one of the associated acknowledged mode (AM) RLC entities.

[0073] Resources that resulted in successful Radio Link Control (RLC) reception

[0074] A successful RLC reception consists of one or more RLC SDUs (Service Data Units), one or more RLC SDU segments, and / or one or more RLC For example, for a receiver UE, successful RLC reception may include transmitting an RLC SDU, an RLC SDU segment, and / or an acknowledgment for an RLC PDU. This may depend on transmitting a status PDU (status report) that carries this information. For a transmitter UE, successful RLC reception may include transmitting an RLC SDU, an RLC SDU segment, and / or an acknowledgment for an RLC PDU. This may include receiving an acknowledgement from the peer RLC entity for the RLC PDU, and / or the RLC PDU, which may be dependent on receiving a status PDU that conveys this information. In some embodiments, more than one acknowledgement may be considered, including, for example, a predetermined number of acknowledgements within a predetermined period or a predetermined number of acknowledgements.

[0075] In another embodiment, successful reception may be inferred by the absence of RLC reception failures. For a receiver UE, this may include RLC PDUs, RLC SDUs, and / or RLC This may include the absence of a negative acknowledgment determination for an SDU segment or the absence of a negative acknowledgment transmission. This may also include the absence of transmitting a Status PDU carrying a negative acknowledgment. For a transmitter UE, successful reception can be inferred based on the absence of receiving a negative acknowledgment from a peer RLC entity. This may include the absence of a Status PDU carrying a negative acknowledgment. In some embodiments, the determination of the absence of RLC reception failure may be performed within a predetermined period and / or may depend on a threshold. For example, the threshold may be less than a predetermined number of negative acknowledgment determinations and / or receptions. As another example, successful reception may be based on a threshold less than a predetermined number of negative acknowledgment determinations and / or receptions within a predetermined period.

[0076] In other embodiments, the condition of successful reception may be inferred by not detecting failure to receive a PDU (e.g., of an Acknowledged Mode Data (AMD) PDU) and / or an SDU. In other embodiments, more than zero failed detections may be considered. For example, successful reception may be determined if fewer than a predetermined number of failed receptions are detected. The determination of the detected failed reception may occur within a predetermined time period.

[0077] In another embodiment, detecting successful reception may include no RLC SDU segments and / or RLC PDUs being detected as lost at a lower layer. In another embodiment, detecting successful reception may include less than a predetermined number of RLC SDU segments and / or RLC PDUs being detected as lost at a lower layer. These determinations may be made at predetermined times.

[0078] In another embodiment, "success" may be determined as successful delivery of a PDU (or upper layer PDU) or successful delivery of several PDUs (or upper layer PDUs). These determinations may be made at a predetermined time.

[0079] In another embodiment, "success" may be defined as the absence of RLC PDUs, RLC data PDUs, or RLC SDUs detected as lost by the receiver, or the absence of less than a predetermined number of RLC data PDUs, RLC PDUs, and / or RLC SDUs detected as lost by the receiver. The determination of the RLC data PDUs, RLC PDUs, and / or RLC SDUs detected as lost may be performed within a predetermined period of time.

[0080] For any of the above, an RLC entity may poll its peer AM RLC entity to trigger a status report at the peer RLC entity.

[0081] For any of the above, the RLC format Status PDU as defined in 3GPP TS 38.322 (NR RLC Protocol) subclause 6.2.2.5 may be reused, or a new RLC format may be defined for the receiver RLC entity to notify the transmitter RLC entity of any of the above. One or more parameters defined under the Status PDU may be reused for the above, or new parameters may be introduced for the above. These parameters may include, for example (as currently defined in the Status PDU), the acknowledgement sequence number AC It may be a K_SN field (sequence number of the next unreceived RLC SDU that has not been reported as missing in a Status PDU), a Data / Control (D / C) field, a Control PDU type CPT, a Negative Acknowledgment Sequence Number NACK_SN (sequence number of the RLC SDU or RLC SDU segment that was detected as missing at the receiver), extension bit 1 E1, extension bit E2, extension bit E3, a reserved field R, an SOstart field (position of the first byte of the RLC SDU portion in bytes within the original RLC SDU), an SOend field (position of the last byte of the RLC SDU portion in bytes within the original RLC SDU), and / or a NACK range field (number of consecutive lost RLC SDUs starting from and including NACK_SN).

[0082] In another embodiment, "success" may be determined when a transmission opportunity has been signaled by the lower layer, or when at least a predetermined number of transmission opportunities have been signaled by the lower layer, which may be determined within a predetermined period of time.

[0083] In another embodiment, "success" may be determined by no errors being corrected by an automatic repeat request (ARQ), fewer than a predetermined number of errors being corrected, or fewer than a predetermined number of errors being corrected within a predetermined period of time.

[0084] In another embodiment, "success" may be determined by no protocol errors being detected, less than a predetermined number of protocol errors being detected, or less than a predetermined number of protocol errors being detected within a certain period of time.

[0085] In another embodiment, "success" may be determined by no duplicates detected, fewer than a predetermined number of duplicates detected, or fewer than a predetermined number of duplicates detected within a certain period of time. Packet duplication of PDUs is specified for NR and RLC examples in 3GPP TS 38.322.

[0086] In any of the above, the predetermined number and / or predetermined period of time may be determined by a standard (e.g., 3GPP The predetermined number and / or the predetermined period may be defined in TS 38.322 Radio Link Control), or may be configured or pre-configured in the UE. For example, the predetermined number and / or the predetermined period may be configured (communicated) to the UE by the network (e.g., by the gNB via RRC signaling), configured (communicated) to the UE by another UE via the PC5 interface, or pre-configured in the UE.

[0087] Resources that resulted in successful Medium Access Control (MAC) reception

[0088] In some embodiments, the resources that resulted in successful MAC reception may include resources in terms of time and / or frequency that resulted in successful HARQ ACKs (acknowledgments) for MAC PDUs, MAC sub-PDUs, and / or MAC SDUs. Instead of one successful HARQ ACK, a predetermined number of ACKs may be used, which may be determined within a predetermined period of time.

[0089] In another embodiment, "success" may be determined by no errors corrected by an automatic repeat request (ARQ) or by fewer than a predetermined number of errors corrected by an ARQ, which may be determined within a predetermined period of time.

[0090] In another embodiment, "success" may be determined as if a transport block (TB) of data is successfully decoded, as if a predetermined number of TBs of data is successfully decoded, or as if at least a predetermined number of TBs of data is successfully decoded, which may be determined within a predetermined period of time.

[0091] In another embodiment, "success" may be determined when decoded MAC PDUs are delivered to the upper layer and / or RLC decomposition and demultiplexing entity. The determination may be based on a predetermined number of MAC PDUs. The determination may apply within a predetermined time period.

[0092] In another embodiment, "success" may be determined when the physical layer is instructed by the RLC to generate an acknowledgement for data within a TB or a predetermined number of TBs. The determination may apply within a predetermined period of time.

[0093] In another embodiment, "success" may be determined if the MAC entity receives no retransmissions for the TB or other resource, if the MAC entity receives fewer than a predetermined number of retransmissions for the TB or other resource, or if the MAC entity does not receive a predetermined number of retransmissions for the TB or other resource. The determination may apply within a predetermined time period. Symmetrically, for a transmitting entity, "success" may be determined based on the absence of retransmissions (rather than the absence of receipt of retransmissions).

[0094] In another embodiment, "success" may be determined if the random access procedure is successfully completed or if fewer than a predetermined number of random access procedures are successfully completed. The determination may apply within a predetermined time period.

[0095] In another embodiment, "success" may be determined when no indication of LBT failure is received at the MAC layer from a lower layer, when fewer than a predetermined number of indications of LBT failure are received from a lower layer, when no consistent LBT failures are determined (or triggered) at the MAC layer, or when fewer than a predetermined number of consistent LBT failures are determined (or triggered) at the MAC layer. Other embodiments include not triggering a scheduling request for an LBT failure MAC control element (CE), not generating an LBT failure MAC CE, and / or not receiving an LBT failure MAC CE (or, in some cases, fewer than a predetermined number or any of them). The conditions used for determination in any of these embodiments may apply within a predetermined period of time. Alternatively or additionally, the protocol data unit (PDU) LBT failure MAC CE defined in subclause 6.1.3.30 of 3GPP TS 38.321 (NR MAC Protocol) may be used and may include any of its existing fields (C0-C24) or rely on new fields. In another embodiment, a new PDU format may be defined for this information.

[0096] In another embodiment, "success" may be determined if there is a MAC transmission opportunity, if there is a predetermined number of MAC transmission opportunities, or if there are more than a predetermined number of MAC transmission opportunities. The determination may apply within a predetermined time period.

[0097] In another embodiment, "success" may be determined if no transmission resource selection or reselection is triggered, if a predetermined number of transmission resource selections or reselections are triggered, or if less than a predetermined number of transmission resource selections or reselections are triggered. The determination may apply within a predetermined time period.

[0098] In another embodiment, "success" may be determined if no beam failures are detected or if fewer than a predetermined number of beam failures are detected. The determination may apply within a predetermined time period. Beam failure detection may include counting beam failure instance indications from lower layers to the MAC entity (e.g., as defined in 3GPP TS 38.321).

[0099] In another embodiment, "success" may be determined in the case of successful conflict resolution or in the case of more than a predetermined number of successful conflict resolutions. The determination may apply within a predetermined period of time.

[0100] Other conditions for determining "success" may include:

[0101] Instructing the physical layer to generate an acknowledgment of data, possibly on a particular TB and / or other resource.

[0102] Instructing the physical layer to generate an acknowledgment corresponding to a transmission on one or more particular channels, such as the PUCCH (Physical Uplink Control Channel).

[0103] An acknowledgement corresponding to a transmission on any channel (e.g., PSSCH) is obtained from the physical layer.

[0104] An acknowledgement (positive response) to the corresponding sidelink HARQ entity is received and / or transmitted (e.g., in the case of a sidelink process).

[0105] HARQ buffers (e.g., associated sidelink processes) are either flushed or not flushed.

[0106] An acknowledgment for the transmission of a MAC PDU has been sent and / or received.

[0107] Other conditions for determining "success" may be inferred by the absence of one or more of the following:

[0108] Instructing the physical layer to generate negative acknowledgements of data, possibly at specific TBs and / or other resources.

[0109] Instructing the physical layer to generate a negative acknowledgement corresponding to a transmission on one or more particular channels, such as the PUCCH.

[0110] A radio link failure, e.g., a HARQ-based sidelink radio link failure, is detected. In some embodiments, this may be based on the number of consecutive DTXs (Discontinuous Transmissions) in a PSFCH (Physical Sidelink Feedback Channel) reception opportunity for a PC5-RRC connection, as described in 3GPP TS 38.321, or may apply to each PSFCH reception opportunity associated with a PSSCH transmission.

[0111] A negative acknowledgement to the corresponding sidelink HARQ entity is received and / or transmitted (e.g., in the case of a sidelink process).

[0112] HARQ buffers (e.g., associated sidelink processes) are either flushed or not flushed.

[0113] A negative acknowledgement to the transmission of a MAC PDU may have been sent and / or received if only negative acknowledgements were enabled on the SCI, or if positive and negative acknowledgements were enabled.

[0114] The number of HARQ retransmissions has been reached and possibly selected by the MAC entity.

[0115] The resources that resulted in the successful reception of the IP packet

[0116] If the IP packet is successfully received, the transmitter UE may send a predetermined field, keyword, or parameter value (possibly in a message, new or existing) to the receiver. The receiver may respond to the transmitter UE with another predetermined field (which may be the same field). A timer may be used on the application side to determine that no response within a predetermined time is a failure (i.e., absence of success).

[0117] Resources that resulted in a successful physical layer connection and / or reception

[0118] The conditions for determining "success" may include one or more of the following:

[0119] The physical layer may be instructed by the MAC layer to generate an acknowledgment of data for a particular resource, for example, TB.

[0120] The physical random access procedure is successful / complete.

[0121] The HARQ-Ack is determined (ACK value) or reported at the physical layer, e.g., sidelink HARQ-Ack.

[0122] The conditions for determining "success" may be inferred by the absence of one or more of the following:

[0123] The physical layer is instructed by the MAC layer to generate a negative acknowledgement of data (e.g., sidelink HARQ-Nack), possibly for a specific resource, e.g., TB.

[0124] Resources that resulted in a successful PC5-RRC (Radio Resource Control) connection and / or reception

[0125] The conditions for determining "success" may include one or more of the following:

[0126] The sidelink RRC connection establishment is successful, e.g., the RRC Setup message is received or sent.

[0127] The RRCReconfigurationCompleteSidelink message is received or sent.

[0128] The conditions for determining "success" may be inferred by the absence of one or more of the following:

[0129] The sidelink RRC connection establishment fails, e.g., an RRCReject is received or sent.

[0130] A sidelink Radio Link Failure (RLF) is detected.

[0131] For example, an indication is received from the sidelink RLC entity that the maximum number of retransmissions has been reached for a particular destination.

[0132] For example, receiving an indication from the MAC entity that the maximum number of consecutive HARQ DTXs has been reached for a particular destination.

[0133] Timer T400 (started when RRCReconfigurationSidelink is sent and stopped when RRCReconfigurationFailureSidelink / RRCReconfigurationCompleteSidelink is received) expires, for example, for a particular destination.

[0134] RRC indicates release of PC5-RRC connection with higher layers for a specific destination (i.e. PC5 is not available).

[0135] The RRCReconfigurationFailureSidelink message is received or sent.

[0136] In the NR example, this may depend on the Radio Resource Control (RRC) NR protocol.

[0137] In any of the schemes of this disclosure, the determination can be based on two or more instances of one particular condition (and / or two or more instances of another condition). The logical functions "or," "exclusive or," or "and" can be used. The determination can be applied within a predetermined period of time. For example, an "erasure timer" may be used. In another (possibly complementary) embodiment, the determination can depend on a continuous condition. The schemes described in this disclosure may be controlled by timers and / or invalidation procedures, after which the scheme is deactivated (i.e., reverts to the legacy process of random detection and / or does not use information about success) after a certain period of time and / or after access / communication failures (e.g., more than a certain number of times within a certain period of time, or more than a certain number of times).

[0138] The above proposed scheme may be used especially by UEs in close proximity and / or UEs traveling at the same or nearly the same speed. Another possible embodiment is that any embodiment of the present disclosure is applied only to UEs in close proximity and / or UEs traveling at the same or nearly the same speed and / or traveling in the same direction.

[0139] In another embodiment, any of the embodiments described in this disclosure may be conditionally applied to UEs in a sidelink coexistence configuration.

[0140] Although the examples provided in this disclosure relate to 3GPP NR (New Radio), embodiments of the present disclosure are not limited to this radio access technology (RAT) and may apply to other RATs, such as LTE / E-UTRA and / or 6G. Although the examples provided in this disclosure relate to 3GPP sidelink, embodiments of the present disclosure are not limited to 3GPP and may apply to other systems, such as (but not limited to), Digital Enhanced Cordless Telecommunications / Digital European Cordless Telecommunications (DECT), IEEE 802.11 (e.g., Wi-Fi), and other wireless communication technologies and protocols.

[0141] User Equipment (UE)

[0142] 2 is a block diagram of a UE 200 consistent with some embodiments of the present disclosure. The UE 200 may be mounted in a moving vehicle, mounted in a fixed location (e.g., as a Roadside Unit (RSU)), or carried by a person. The UE 200 may be mounted in any of a variety of locations, including, but not limited to, a vehicle, a vehicle-mounted component, an RSU, a laptop computer, a mobile phone, etc. The UE 200 may take any form, including a wireless terminal, a wireless handheld device, a wireless personal device, or any other form. Referring to FIG. 2, the UE 200 may include an antenna 202 that may be used for transmission and / or reception of electromagnetic signals to and from a base station or another UE. The antenna 202 may include one or more antenna elements and may enable different input / output antenna configurations, including a multiple-input multiple-output (MIMO) configuration, a multiple-input single-output (MISO) configuration, and a single-input multiple-output (SIMO) configuration. In some embodiments, the antenna 202 may include multiple (e.g., tens or hundreds) antenna elements and may enable multi-antenna functions such as beamforming. In some embodiments, the antenna 202 is a single antenna.

[0143] The UE 200 may include a transceiver 204 coupled to the antenna 202. The transceiver 204 may be a wireless transceiver in the UE 200 and may communicate bidirectionally with a base station or other UEs. For example, the transceiver 204 may receive wireless signals from a base station via downlink and transmit wireless signals to the base station via uplink communication. The transceiver 204 may also receive wireless signals from and transmit wireless signals to another UE or a roadside unit (RSU) via sidelink communication. The transceiver 204 may include a modem for modulating packets, providing the modulated packets to the antenna 202 for transmission, and demodulating packets received from the antenna 202.

[0144] The UE 200 may include memory 206. The memory 206 may be any type of computer-readable storage medium, including volatile or non-volatile memory devices, or a combination thereof. Computer-readable storage media include, but are not limited to, non-transitory computer storage media. Non-transitory storage media may be accessed by a general-purpose or special-purpose computer. Examples of non-transitory storage media include, but are not limited to, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable ROM (EEPROM), digital versatile disks (DVDs), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage, etc. The non-transitory medium may be used to carry or store desired program code means (e.g., instructions and / or data structures) and may be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. In some examples, the software / program code may be transmitted from a remote source (e.g., a website, a server, etc.) using coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, microwave, etc. In such examples, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are within the definition of media. Combinations of the above examples are also within the scope of computer-readable media.

[0145] The memory 206 may store information regarding the identification of the UE 200 and signals and / or data received by the antenna 202. The memory 206 may also store post-processed signals and / or data. The memory 206 may also store computer-readable program instructions, mathematical models, and algorithms used in signal processing in the transceiver 204 and calculations in the processor 208. The memory 206 may further store computer-readable program instructions executed by the processor 208 to operate the UE 200 to perform various functions described elsewhere in this disclosure. In some examples, the memory 206 may include a basic input / output system (BIOS) that may control basic hardware or software operations such as interaction with peripheral components or devices.

[0146] The computer-readable program instructions of the present disclosure may be assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​and conventional procedural programming languages. The computer-readable program instructions may execute entirely on a computing device as a standalone software package, or partially on a first computing device and partially on a second computing device remote from the first computing device. In the latter scenario, the second, remote computing device may be connected to the first computing device via any type of network, including a local area network (LAN) or a wide area network (WAN).

[0147] The UE 200 may include a processor 208, which may include hardware devices having processing capabilities. The processor 208 may include at least one of a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or another programmable logic device. Examples of a general-purpose processor include, but are not limited to, a microprocessor, any conventional processor, controller, microcontroller, or state machine. In some embodiments, the processor 208 may be implemented using a combination of devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration). The processor 208 can receive downlink or sidelink signals from the transceiver 204 and further process the signals. The processor 208 can also receive data packets from the transceiver 204 and further process the packets. In some embodiments, the processor 208 may be configured to operate the memory using a memory controller. In some embodiments, the memory controller may be integrated into the processor 208. The processor 208 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 206) to cause the UE 200 to perform various functions.

[0148] The UE 200 may include a global positioning system (GPS) 210. The GPS 210 may be used to enable location-based services or other services based on the geographic location of the UE 200 and / or for synchronization between UEs. The GPS 210 may receive a global navigation satellite system (GNSS) signal from a single satellite or multiple satellite signals via the antenna 202 and provide the geographic location of the UE 200 (e.g., the coordinates of the UE 200).

[0149] The UE 200 may include an input / output (I / O) device 212 that can be used to communicate the results of signal processing and calculations to a user or another device. The I / O device 212 may include a user interface including a display and an input device for sending user commands to the processor 208. The display may be configured to display the status of signal reception at the UE 200, data stored in the memory 206, the status of signal processing, and calculation results. The display may be, but is not limited to, a cathode ray tube (CRT), a liquid crystal display (LCD), a light emitting diode (LED), a gas plasma display, a touch screen, or any other suitable display for displaying information to a user. An input device may include other image projection devices. An input device may be any type of computer hardware device used to receive data and control signals from a user. Input devices may include, but are not limited to, a keyboard, a mouse, a scanner, a digital camera, a joystick, a trackball, cursor direction keys, a touchscreen monitor, or an audio / video commander.

[0150] The UE 200 may further include a machine interface 214 , such as an electrical bus, that connects the transceiver 204 , the memory 206 , the processor 208 , the GPS 210 , and the I / O device 212 .

[0151] In some embodiments, the UE 200 may be configured or programmed for sidelink communication. The processor 208 may be configured to execute instructions stored in the memory 206 to perform a method for selecting sidelink radio resources by the UE 200, such as the method 100 described in connection with FIG.

[0152] As used in this disclosure, the use of the term "or" in a list of items indicates an inclusive list. A list of items can begin with a phrase such as "at least one" or "one or more." For example, a list of at least one of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in this disclosure, the phrase "based on" preceding a list of conditions should not be interpreted as "based only on" the set of conditions, but rather as "based at least in part on" the set of conditions. For example, a result described as "based on condition A" can be based on both condition A and condition B without departing from the scope of this disclosure.

[0153] As used herein, the terms "comprise," "include," or "contain" may be used interchangeably, have the same meaning, and should be construed as inclusive and open-ended. The terms "comprise," "include," or "contain" may be used before a list of elements to indicate that at least all of the listed elements in the list are present, but that other elements not in the list may also be present. For example, if A contains B and C, then both {B, C} and {B, C, D} are within the scope of A.

[0154] The present disclosure, in connection with the accompanying drawings, describes exemplary configurations that do not represent every example that may be implemented or every configuration within the scope of the present disclosure. The term "exemplary" should not be interpreted as "preferred" or "advantageous compared to other examples," but rather as "an example, instance, or example." By reading this disclosure, including the description of the embodiments and drawings, those skilled in the art will understand that the technology disclosed herein may be implemented using alternative embodiments. Those skilled in the art will understand that embodiments, or specific features of the embodiments described herein, can be combined to arrive at yet other embodiments for implementing the technology described in this disclosure. Thus, the present disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0155] The flowcharts and block diagrams in the figures illustrate example architecture, functionality, and operation of possible implementations of systems, methods, and devices according to various embodiments. It should be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. Similarly, methods consistent with various embodiments may also be implemented. In such methods, additional steps may be included and certain steps may be omitted or combined.

[0156] It is understood that the described embodiments are not mutually exclusive, and that elements, components, materials, or steps described in connection with one exemplary embodiment may be combined with, or excluded from, other embodiments in any suitable manner to achieve desired design objectives.

[0157] References herein to "some embodiments" or "some exemplary embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment. The appearances of the phrases "one embodiment," "some embodiments," or "another embodiment" in various places in this disclosure do not necessarily all refer to the same embodiments, or necessarily to separate or alternative embodiments that are mutually exclusive of other embodiments.

[0158] Furthermore, the articles "a" and "an," as used in this disclosure and the appended claims, should generally be construed to mean "one or more," unless otherwise specified or unless it is clear from the context that the singular form is intended.

[0159] Unless otherwise stated, each numerical value and range should be construed as being approximate as if the word "about" or "approximately" preceded the value or range value.

[0160] Although elements in the following method claims, if present, are recited in a particular order, it is not intended that the elements be necessarily limited to being implemented in that particular order, unless the recitation of a claim specifically implies a particular order for implementing some or all of those elements.

[0161] It is understood that certain features of the present disclosure, which are for clarity described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features herein that are for brevity described in the context of a single embodiment may also be provided separately or in any suitable subcombination, or as appropriate, in any other described embodiment herein. Certain features described in the context of various embodiments are not essential features of those embodiments, unless so stated.

[0162] It will be further understood that various modifications, substitutions, and variations in the details, materials, and arrangements of parts described and illustrated to explain the nature of the described embodiments may be made by those skilled in the art without departing from the scope of the present disclosure, and it is therefore intended that the following claims encompass all such substitutions, modifications, and variations that fall within the terms of the claims.

[0163] Supplementary Note 1. A method for selecting sidelink radio resources by a user equipment (UE), comprising: transmitting from the UE to one or more receivers on selected radio resources; determining whether the UE successfully transmitted on the selected radio resource; identifying the selected radio resource as a preferred radio resource based on a determination that the UE successfully transmitted on the selected radio resource; prioritizing transmission on preferred radio resources at a next transmission opportunity by the UE; Includes:

[0164] Appendix 2. Selecting a radio resource from a resource pool as the selected radio resource 2. The method of claim 1, further comprising:

[0165] Supplementary Note 3. The method of Supplementary Note 2, wherein the resource pool is provided to the UE by configuration or pre-configuration.

[0166] Supplementary Note 4. The method of Supplementary Note 1, wherein determining whether the UE has successfully transmitted on the selected radio resource includes determining whether the selected radio resource is available after sensing on one or more radio resources.

[0167] Supplementary Note 5. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource includes the step of determining the absence of collisions on the selected radio resource during transmission.

[0168] Clause 6. The method of clause 5, wherein the absence of a collision is determined based on not detecting a collision within a predetermined period of time after transmission.

[0169] Supplementary Note 7. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource is determined based on responses received from one or more receivers within a predetermined period of time after the transmission.

[0170] 8. The method of claim 1, wherein determining whether the UE has successfully transmitted on the selected radio resource includes determining that there has been a previous successful reception by one or more receivers from the UE on the selected radio resource.

[0171] Supplementary Note 9. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource comprises determining that an acknowledgement of a hybrid automatic repeat request has been received for the transmission.

[0172] Supplementary Note 10. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource comprises determining that no hybrid automatic repeat request negative acknowledgement is received for the transmission within a predetermined period of time.

[0173] Supplementary Note 11. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in receipt of a successful radio link control signal.

[0174] Supplementary Note 12. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in the reception of a successful radio link control service data unit.

[0175] Supplementary Note 13. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in the reception of a successful radio link control service data unit segment.

[0176] Supplementary Note 14. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in the reception of a successful radio link control protocol data unit.

[0177] Supplementary Note 15. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in receipt of a successful medium access control signal.

[0178] Supplementary Note 16. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource comprises determining that the transmission resulted in acknowledgments of a predetermined number of hybrid automatic repeat requests.

[0179] Supplementary Note 17. The method of Supplementary Note 1, wherein the step of determining whether the UE has successfully transmitted on the selected radio resource comprises determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgments within a predetermined period of time.

[0180] Supplementary Note 18. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in the reception of a successful Internet Protocol packet.

[0181] Supplementary Note 19. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in a successful physical layer connection.

[0182] Supplementary Note 20. The method of Supplementary Note 1, wherein the step of determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in successful physical layer reception.

[0183] Clause 21. The method of clause 20, wherein successful physical layer reception is on a physical uplink control channel.

[0184] 22. The method of claim 20, wherein successful physical layer reception is on a physical sidelink shared channel.

[0185] Supplementary Note 23. The method of Supplementary Note 1, wherein the step of determining whether the UE has transmitted successfully is based on using random resource selection.

[0186] Clause 24. The method of clause 23, wherein the preferred radio resource has a higher probability than one or more other radio resources.

[0187] Clause 25. The step of identifying the selected radio resource as a preferred radio resource comprises: identifying the selected radio resource as a preferred radio resource after a predetermined number of successful transmissions using the selected radio resource. The method described in Appendix 1.

[0188] Clause 26. The step of identifying the selected radio resource as a preferred radio resource comprises: identifying the selected radio resource as a preferred radio resource after a predetermined number of successful transmissions using the selected radio resource within a predetermined time period. The method described in Appendix 1.

[0189] Clause 27. Selecting a preferred radio resource based on sensing on one or more radio resources; transmitting on a preferred radio resource; 2. The method of claim 1, further comprising:

[0190] Appendix 28. Storing identifiers of preferred radio resources in a memory of the UE 2. The method of claim 1, further comprising:

[0191] Supplementary Note 29. A user equipment (UE) for selecting sidelink radio resources by the UE, the UE comprising: a memory configured to store instructions; a processor; Including, The processor executes instructions stored in memory to transmitting from the UE to one or more receivers on the selected radio resources; determining whether the UE successfully transmitted on the selected radio resource; Identifying the selected radio resource as a preferred radio resource based on a determination that the UE successfully transmitted on the selected radio resource; prioritizing transmission on preferred radio resources at the next transmission opportunity by the UE; It is configured as follows.

[0192] Addendum 30. The processor selects a radio resource from a resource pool as the selected radio resource. 30. The UE of claim 29, further configured

[0193] Supplementary Note 31. The UE of Supplementary Note 30, wherein the resource pool is provided to the UE by configuration or pre-configuration.

[0194] Appendix 32. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining whether the selected radio resource is available after sensing on one or more radio resources.

[0195] Supplementary Note 33. The UE of Supplementary Note 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining the absence of collisions on the selected radio resource during transmission.

[0196] Clause 34. The UE of Clause 33, wherein the absence of a collision is determined based on not detecting a collision within a predetermined period of time after transmission.

[0197] Supplementary Note 35. The UE of Supplementary Note 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource based on a response received from one or more receivers within a predetermined period after the transmission.

[0198] Clause 36. The UE of Clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that there was previous successful reception by one or more receivers from the UE on the selected radio resource.

[0199] Clause 37. The UE of Clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that an acknowledgment of the hybrid automatic repeat request was received for the transmission.

[0200] Clause 38. A processor may detect the rejection of a hybrid automatic repeat request for a transmission within a predetermined period of time. 30. The UE of claim 29, further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that a constant response is not received.

[0201] Clause 39. The UE of Clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in receipt of a successful radio link control.

[0202] Appendix 40. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in the reception of a successful radio link control service data unit.

[0203] Supplementary Note 41. The UE of Supplementary Note 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in the reception of a successful radio link control service data unit segment.

[0204] Appendix 42. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in the reception of a successful radio link control protocol data unit.

[0205] Supplementary Note 43. The UE of Supplementary Note 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in receipt of a successful medium access control.

[0206] Clause 44. The UE of Clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgments.

[0207] Supplementary Note 45. The UE of Supplementary Note 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgments within a predetermined period of time.

[0208] Appendix 46. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in the receipt of a successful Internet Protocol packet.

[0209] Appendix 47. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in a successful physical layer connection.

[0210] Appendix 48. The UE of Appendix 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that the transmission resulted in successful physical layer reception.

[0211] Clause 49. The UE of Clause 48, wherein successful physical layer reception is on a physical uplink control channel.

[0212] Clause 50. The UE of clause 48, wherein successful physical layer reception is on a physical sidelink shared channel.

[0213] Appendix 51. A processor for selecting a resource for a UE to transmit based on using random resource selection. 30. The UE of claim 29, further configured to determine whether the communication was successful.

[0214] Clause 52. The UE of Clause 51, wherein the preferred radio resource has a higher probability than one or more other radio resources.

[0215] Clause 53. The UE of Clause 29, wherein the processor is further configured to identify the selected radio resource as a preferred radio resource after a predetermined number of successful transmissions using the selected radio resource.

[0216] Clause 54. The UE of Clause 29, further configured to identify the selected radio resource as a preferred radio resource after a predetermined number of successful transmissions using the selected radio resource within a predetermined period of time.

[0217] Appendix 55. The processor: selecting a preferred radio resource based on sensing on the one or more radio resources; Transmitting on a suitable radio resource; 30. The UE of claim 29, further configured

[0218] Appendix 56. The processor: storing identifiers of the preferred radio resources in a memory; 30. The UE of claim 29, further configured

[0219] Clause 57. A non-transitory computer-readable medium storing instructions executable by one or more processors of user equipment (UE) in a communications network to perform a method, the method comprising: transmitting from the UE to one or more receivers on selected radio resources; determining whether the UE successfully transmitted on the selected radio resource; identifying the selected radio resource as a preferred radio resource based on a determination that the UE successfully transmitted on the selected radio resource; prioritizing transmission on preferred radio resources at a next transmission opportunity by the UE; Includes:

Claims

1. 1. A method for selecting sidelink radio resources by a user equipment (UE), comprising: transmitting from the UE to one or more receivers on selected radio resources; determining whether the UE successfully transmitted on the selected radio resource; identifying the selected radio resource as a preferred radio resource based on a determination that the UE successfully transmitted on the selected radio resource; prioritizing transmission on the preferred radio resource at a next transmission opportunity by the UE; A method comprising:

2. 2. The method of claim 1, wherein determining whether the UE successfully transmits on the selected radio resource comprises determining whether the selected radio resource is available after sensing on one or more radio resources.

3. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining an absence of collisions on the selected radio resource during transmission.

4. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource is determined based on responses received from the one or more receivers within a predetermined period after the transmission.

5. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that there was a previous successful reception by the one or more receivers from the UE on the selected radio resource.

6. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that a hybrid automatic repeat request acknowledgment was received for the transmission.

7. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that a hybrid automatic repeat request negative acknowledgment is not received for the transmission within a predetermined period of time.

8. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in successful reception of a radio link control signal.

9. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in the reception of a successful radio link control service data unit.

10. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in the reception of a successful radio link control service data unit segment.

11. A step of determining whether the UE has successfully transmitted on the selected radio resource.

2. The method of claim 1, further comprising determining that the transmission resulted in the reception of a successful radio link control protocol data unit.

12. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in successful reception of a medium access control signal.

13. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgments.

14. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgments within a predetermined period of time.

15. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in the reception of a successful Internet Protocol packet.

16. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in a successful physical layer connection.

17. 2. The method of claim 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in successful physical layer reception.

18. identifying the selected radio resource as a preferred radio resource; identifying the selected radio resource as the preferred radio resource after a predetermined number of successful transmissions using the selected radio resource. The method of claim 1.

19. identifying the selected radio resource as a preferred radio resource; identifying the selected radio resource as the preferred radio resource after a predetermined number of successful transmissions using the selected radio resource within a predetermined time period. The method of claim 1.

20. selecting the preferred radio resource based on sensing on one or more radio resources; transmitting on the preferred radio resource; The method of claim 1 further comprising:

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