Channel access mechanism in wireless communication

Abstract

A method of selecting a sidelink radio resource by a user equipment (UE), comprising: transmitting from the UE to one or more recipients on a selected radio resource; determining whether the UE successfully transmits on the selected radio resource; identifying the selected radio resource as a preferred radio resource based on a determination that the UE successfully transmits on the selected radio resource; and preferentially transmitting on the preferred radio resource based on the next transmission opportunity of the UE.

Description

Cross-references to related patent applications

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 371,039, filed on August 10, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to channel access mechanisms in wireless communications, and more particularly, to selection of sidelink radio resources by a user equipment for transmission. Background Art

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

[0004] In some embodiments, a method for selecting a sidelink radio resource by a user equipment (UE) is provided. The method includes: transmitting from the UE to one or more recipients on the selected radio resource; determining whether the UE successfully transmitted on the selected radio resource; based on the determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; and in the next transmission opportunity of the UE, preferentially transmitting on the preferred radio resource.

[0005] In some embodiments, a user equipment (UE) for selecting a sidelink radio resource 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 from the UE to one or more recipients on the selected radio resource; determine whether the UE successfully transmitted on the selected radio resource; based on the determination that the UE successfully transmitted on the selected radio resource, identify the selected radio resource as a preferred radio resource; and prioritize transmission on the preferred radio resource in the next transmission opportunity of the UE.

[0006] In some embodiments, a non-transitory computer-readable medium is provided, the non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors of a user equipment (UE) in a communication network to perform a method. The method includes: transmitting from the UE to one or more recipients on a selected radio resource; determining whether the UE successfully transmitted on the selected radio resource; based on the determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; and, in a next transmission opportunity of the UE, preferentially transmitting on the preferred radio resource.

[0007] The above and other aspects and embodiments thereof are described in more detail in the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [ Figure 1 ] Figure 1 is a flow chart of a method of selecting sidelink radio resources by a user equipment (UE) consistent with some embodiments of the present disclosure.

[0009] [ Figure 2 ] Figure 2 is a block diagram of a UE consistent with some embodiments of the present disclosure. DETAILED DESCRIPTION

[0010] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which the same reference numerals in different drawings represent the same or similar elements, unless otherwise specified. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of devices, systems, and methods consistent with aspects related to the subject matter that may be recited in the appended claims.

[0011] In general, one or more aspects of the present disclosure relate to autonomous sensing of radio resources or radio resource reservation. 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.

[0012] Sidelink and Sensing

[0013] Resources are defined using time and frequency. In the case where the UE allocates resources autonomously, for the resource (re)selection mechanism for SL, sensing-based resource selection can perform resource exclusion based on sensing information, followed by resource selection from the remaining candidate resources, which involves randomness. The UE can also perform resource selection based on randomness without sensing (called "random resource selection"). Release 14 / 15 LTESL and Release 16 / 17 NRSL already support these two options. Sensing-based resource selection achieves reliable communication by avoiding resource conflicts as much as possible, but due to the sensing operation, its power consumption and complexity are higher than random resource selection. Since no sensing operation is required, random resource selection is more suitable for battery-constrained devices, but they may experience increased resource conflicts. In general, channel access waiting time is not a problem in sensing-based resource selection because sensing can be performed continuously in the background. The channel access waiting time of both solutions can be controlled by the packet delay budget parameter.

[0014] Listen-Before-Talk (LBT) sensing has been used for potential wireless transmitters in unlicensed spectrum (NR-U) in 3GPP NR (New Radio), and in unlicensed spectrum in LTE (e.g., LTE Licensed Assisted Access in Release 13).

[0015] 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 considered "busy" (e.g., by determining a received energy detection threshold during a specified duration), the potential transmitter will not transmit. If the channel is considered "idle" (e.g., the received energy is below a threshold), the transmitter will transmit at a later time, as specified in the standard.

[0016] In 3GPP, there are two types of LBT techniques. The first LBT technique is a "load-based device" approach, where a potential transmitter senses the channel when it needs to transmit (with possible some postponement periods). The second LBT technique is a "frame-based device" approach, where a potential transmitter senses the channel at fixed times. These LBT mechanisms (especially load-based devices) include some "temporal randomness" and "back-off" to provide different UEs with a fair chance to access the channel and avoid continuous conflicts that would block the channel. For example, some random "back-off" periods can be used before transmission.

[0017] In order to provide some opportunities for other UEs (i.e., UEs other than the UE accessing the channel) to access the channel, the 3GPP technical specification provides a "channel occupation time", which defines the total duration that the eNB / gNB / UE and any eNB / gNB / UE sharing the channel occupation perform (one or more) transmissions on the channel after the eNB / gNB / UE performs the corresponding channel access procedure. To determine the channel occupation time, if the transmission gap is less than or equal to 25μs, the gap duration is counted in the channel occupation time. The channel occupation time can be shared for transmissions between the eNB / gNB and (one or more) corresponding UEs. After this duration expires, new sensing will be required.

[0018] In LTE sidelink and NR sidelink, sensing is performed to collect resource reservation information from other UEs and measure the Sidelink Reference Signal Received Power (SL-RSRP) and Sidelink Received Signal Strength Indicator (SL-RSSI) so that the transmitting UE can determine the available resources in the selection window.

[0019] Randomly selecting 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 conflicts will occur between different UEs, resulting in performance degradation and fewer (or no) UEs able to communicate.

[0020] Different priority classes are allowed in NR-U Release 16 resulting in different "backoff" periods and different channel occupancy times to try to advantage some UEs over other UEs of different priority classes. However, this does not change the "random" nature of initial channel access (especially for UEs within a particular priority class).

[0021] For NR sidelink Release 16, the UE can make its radio resource (re)selection based on sensing within a resource pool (for resource allocation mode 2). The resource pool provided to the UE by configuration or pre-configuration (for example, provided to a UE with or without a Subscriber Identity Module (SIM) / Universal Subscriber Identity Module (USIM)) is defined in the frequency domain according to subchannels and in the time domain according to time slots or subframes. The selected frequency resources can be used multiple times for subsequent transmissions at fixed time intervals (this scheme is called Semi-Persistent Scheduling (SPS)) or only once (this scheme is called One-Shot Transmission (OST)). Moreover, the UE can retransmit the packet multiple times with or without feedback from one or more receiving UEs to improve reliability (this is called hybrid automatic repeat request or HARQ retransmission).

[0022] In addition, the transmitting UE can perform resource reservation notification for the transmission of the next transport block and (one or more) retransmissions of the current transport block to provide other UEs with information about which resources the transmitting UE has selected for future sidelink transmissions (so that other UEs avoid those resources). This information is provided to other UEs via 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" also contains information for demodulating / detecting another physical channel (the physical sidelink shared channel (PSSCH) carrying sidelink data) and also contains the "second stage SCI" for control signaling. However, with all of this, the transmitting UE autonomously selects some idle available resources with some (uniformly distributed) random components. In addition, this does not change the problem of possible conflicts due to the random component of resource (re)selection.

[0023] In NR-U Release 16, channel access type 2 (including type 2A, 2B or 2C) can be used after initiating a transmission after the initial sensing (type 1). This involves sending some additional transmissions almost immediately after the initial transmission. Depending on the size of the gap between the two transmissions, procedures 2A, 2B or 2C can be used. Procedures 2A or 2B require sensing and procedure 2C does not require sensing. This does not solve the above problems because they represent a "short-term" transmission of additional data within the Channel Occupancy Time (COT), after which the "type 1" channel access procedure will start again.

[0024] For 3GPP LTE V2X PC5 Mode 4, similar to Release 16 NR-V2X PC5 Mode 2, the UE selects radio resources based on sensing and performs transmissions based on SPS and OST. In addition, the UE can select and reserve resources based on sensing and geographic area (e.g., as defined in 3GPP TR 37.985), where the UE performs transmissions within a resource pool associated with its current area. However, this is for resource reservation after sensing. Sensing and resource selection still suffer from the above-mentioned problems (i.e., possible conflicts with (one or more) other UEs using the same resource pool).

[0025] UE uses previously successful resources

[0026] One solution to the above problem is that when or after performing sensing and / or resource (re) selection, the UE uses some previously successful resources instead of some random resources. Previously successful resources can be defined as including resources that have resulted in successful transmissions in the past. For example, resources that result in idle channels, the absence of conflicts after transmissions after sensing an idle channel, and / or previous successful reception by one or more recipients. The absence of conflicts after transmissions after sensing an idle channel can be determined by using a timer (which can be preconfigured). A reply (including an explicit affirmative reply) from a recipient (possibly within a predetermined time period) can be determined as "successful".

[0027] For the time dimension of those resources, some time slots (or sub-time slots) may be defined as references. A UE performing initial sensing may use time slot (or sub-time slot) numbers similar to previous successful time slots. The time slot numbers may be defined using a synchronization reference.

[0028] For example, if the resource selection in one transmission opportunity is successful in the sense that the receiver acknowledges successful reception of the data, then there is no conflict. In that case, it may be advantageous to reuse the same resource for subsequent transmission opportunities based on the principle 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.

[0029] In some implementations, the selected resources may be used multiple times for subsequent transmissions at fixed time intervals in a scheme known as semi-persistent scheduling (SPS), or used only once in a scheme known as one-time transmission (OST). The difference between the proposed modification and the existing SPS scheme is that the transmitting UE reuses the resource only if the resource was previously successful. The benefit of a successful resource reuse approach is that the permanent packet loss problem caused by resource conflicts, half-duplex and / or near-far problems in SPS can be alleviated. SPS is currently supported in Release 16 / 17 NR SL for both sensing-based resource selection and random resource selection.

[0030] Prior success resources may be defined under different possible implementations, including:

[0031] The resources (in terms of time and / or frequency) that resulted in successful sensing. For example, using a clear channel determination, or using a collision-free check and / or receiving a reply from the receiver.

[0032] The resource(s) (in time and / or frequency) that resulted in successful Medium Access Control (MAC) reception.

[0033] The resource(s) that resulted in successful Packet Data Convergence Protocol (PDCP) reception.

[0034] The resource(s) that resulted in a successful Internet Protocol (IP) packet reception.

[0035] The resource(s) that resulted in successful Radio Link Control (RLC) Service Data Unit (SDU) / Protocol Data Unit (PDU) reception.

[0036] The resource(s) that resulted in a successful physical layer connection and / or reception.

[0037] Resulting in a successful PC5 - Radio Resource Control (RRC) connection and / or received resource(s).

[0038] As used herein, the term "successful" may be defined as including one or more successes as defined above. In some disclosed embodiments, "successful" may include one previous success or N previous successes, where N is an integer greater than 1.

[0039] Previously successful resources may also be referred to as "preferred resources". In the above process, preferred resources may be used to modify sensing. For example, instead of the UE randomly selecting among the available resources (i.e., with a uniformly distributed probability), preferred resources may be associated with a higher probability than non-preferred resources (e.g., twice as high). The distribution rules may be defined in the standard; provided to the UE via network configuration (e.g., via radio resource control (RRC) signaling); and / or provided to the UE via pre-configuration. As another example, preferred resources may be used to bypass initial sensing, i.e., preferred resources may be used as initial resource configuration.

[0040] Figure 1 1 is a flow chart of a method 100 for selecting a sidelink radio resource by a user equipment (UE) consistent with some embodiments of the present disclosure. A radio resource is selected by the UE, and the UE transmits to one or more recipients on the selected radio resource (step 102). It is determined whether the UE successfully transmits on the selected radio resource (step 104). The term "successful transmission" 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 resource (step 104, "no" branch), the UE selects a radio resource (step 106), and the method 100 returns to step 102 to attempt to transmit on other selected radio resources. In some embodiments, the radio resource is another radio resource different from the selected radio resource used in step 104. In other embodiments, if the UE does not successfully transmit on the selected radio resource (step 104, "no" branch), the UE selects a radio resource different from or the same as the previously selected radio resource (step 106), for example, each time step 106 is performed, the previously selected radio resource is added to a potential radio resource pool from which the radio resource is selected.

[0041] If the UE successfully transmits on the selected radio resource (step 106, "yes" branch), the selected radio resource is identified as the preferred radio resource (step 108). In some embodiments, the identifier of the preferred radio resource may be stored (step 110). It should be noted that storing the identifier of the preferred radio resource is optional. Figure 110. 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, time slot or subframe in the time domain. In the next transmission opportunity, the UE preferentially transmits on the preferred radio resource (step 112).

[0042] 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.

[0043] In some embodiments, determining whether the UE successfully transmits on the selected radio resource comprises determining whether the selected radio resource is available after sensing of one or more radio resources.

[0044] In some embodiments, determining whether the UE successfully transmits on the selected radio resource comprises determining that there is no conflict on the selected radio resource during the transmission. The absence of conflict may be determined based on no conflict being detected within a predetermined time period after the transmission.

[0045] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource is determined based on receiving a reply from one or more recipients within a predetermined time period after the transmission.

[0046] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource comprises determining that there was a previous successful reception from the UE on the selected radio resource by one or more recipients.

[0047] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource comprises determining receipt of a hybrid automatic repeat request acknowledgment for the transmission.

[0048] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource comprises determining that a hybrid automatic repeat request negative acknowledgement for the transmission was not received within a predetermined time period.

[0049] In some embodiments, determining whether the UE successfully transmitted on the selected radio resource includes: determining that the transmission resulted in any of the following: successful radio link control reception, successful radio link control service data unit reception, successful radio link control service data unit segment reception, successful radio link control protocol data unit reception, successful medium access control reception, a predetermined number of hybrid automatic repeat request acknowledgments, a predetermined number of hybrid automatic repeat request acknowledgments within a predetermined time period, successful internet protocol packet reception, successful physical layer connection, or successful physical layer reception. The successful physical layer reception may be, for example, on a physical uplink control channel or on a physical sidelink shared channel.

[0050] In some embodiments, whether the UE successfully transmits is based on using random resource selection.The preferred radio resource may have a higher probability than one or more other radio resources.

[0051] 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.

[0052] In some embodiments, the method 100 further comprises: selecting a preferred radio resource based on sensing of one or more radio resources, and transmitting on the preferred radio resource.

[0053] In some embodiments, the preferred resources are applied to the UE that successfully transmits the first burst (eg, radio frame) in the communication exchange.The UE that successfully transmits may also be referred to herein as a transmitting UE or transmitting UE.

[0054] In another embodiment, a receiving UE that successfully communicates with a transmitting UE while not triggering an initial burst may consider this initial resource to be not allowed (and / or deprioritized, for example, by having a lower probability of allocation), such that it remains "reserved" for the transmitting UE. The opposite is also possible, i.e., the initial transmitting UE deprioritizes the resource, and the initial receiving UE prioritizes the resource.

[0055] In another embodiment, the transmitting UE determines preferred resources and non-preferred resources at a subchannel level (a set of resource blocks) or a resource block level in the frequency domain.

[0056] In another embodiment, the transmitting UE uses different probabilities according to the packet priority. The probabilities of different packet priorities are configured or preconfigured, defined by the 3GPP specification, or up to the implementation or higher layer. "Priority" here can be a priority class (currently 1 to 4) or can be other priorities, such as PPPP (ProSe Per-Packet Priority), logical channel priority and / or quality of service priority.

[0057] In another embodiment, the transmitting UE uses different probabilities depending on its radio access capabilities or radio access technology (e.g., LTE or NR) and / or depending on the radio access capabilities valid for access.

[0058] In other embodiments, any of the above idea(s) may be used for resource selection following (instead of or in addition to) initial sensing.

[0059] In other embodiments, any of the above idea(s) may be used for resource selection without using initial sensing.

[0060] In other embodiments, any of the above idea(s) may be used to bypass potential sensing, for example by assigning a probability of "1" to some resources.

[0061] UE provides information to other UE(s)

[0062] In another embodiment, a transmitting UE with a previous successful transmission, reception, or communication may transmit to other UEs (in unicast, groupcast, or broadcast) an identification of the channel (time and / or frequency) that the initial transmission was successfully used for the transmitting UE. Other UEs may interpret this information as resources reserved by the transmitting UE and will avoid using the reserved resources for initial access. For example, this information may be provided as part of the "first stage SCI" described above. As another example, this information may be provided as a sidelink UE-to-UE communication or message.

[0063] Use area information for initial sensing

[0064] In another embodiment, the UE may use geographic location or area information for initial sensing associated with initial access. This information may define a set of times and / or frequencies of resources to be used for initial sensing. Using this information can help avoid situations where two nearby UEs attempt to use similar resources.

[0065] Any of the above options may be configured through RRC signaling or may be pre-configured in the UE.

[0066] Resources that lead to successful Packet Data Convergence Protocol (PDCP) reception

[0067] For the example of 5G NR, successful PDCP reception may rely on successful reception as defined in 3GPP TS 38.323 (NR PDCP protocol). For a transmitting UE, successful reception may include successful delivery of a PDCP SDU, which may be confirmed by a received PDCP status report. For a receiving UE, successful reception may include sending a PDCP status report reporting successful delivery (i.e., receipt by the transmitting UE) of the PDCP SDU.

[0068] Note that the status report can rely on existing status reports from 3GPP TS 38.323, which uses a PDCP control PDU to convey the PDCP status report. Any existing fields inside the PDCP status report can be used to further distinguish the conditions (i.e., the condition is not just receiving a PDU). The condition can be more selective. In the example of relying on the D / C (data / control) field, it can be indicated that a data PDU is received relative to a control PDU. For example, the D / C field can 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 can also be used. For example, a bitmap field can be used to indicate which SDUs are lost and which SDUs are received correctly in the receiving PDCP entity.

[0069] In other embodiments, successful reception may be determined if at least one PDCP SDU is correctly received, if at least one PDCP SDU is correctly received without PDCP SDU loss, or if the number of correctly received PDCP SDUs is higher than the number of lost PDCP SDUs. Comparing the number of correctly received PDCP SDUs to the number of lost PDCP SDUs may be performed by a ratio or provided to the UE by configuration (e.g., by RRC configuration or pre-configuration). In other embodiments, successful reception may be determined if the number of correctly received PDCP SDUs is equal to or higher than a threshold and / or the number of lost PDCP SDUs is equal to or lower than a threshold. These thresholds may be defined in, for example, 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 conditions described above for determining successful reception is possible.

[0070] In another embodiment, the status report from subclause 6.2.3.1 of 3GPP TS 38.323 may be reused with new fields added. For example, the determination condition may be on the transmitting side of the status report rather than on the receiving side of the status report. For example, a new field such as 'Reception f Success' may be defined.

[0071] [Table 1] New table: Receive success field Bit describe 0 Receiving failed 1 Received successfully

[0072] In addition to the currently existing triggers for sending PDCP status reports in 3GPP TS 38.323 (PDCP entity re-establishment, PDCP data recovery, uplink data switching, or PDCP entity reconfiguration requested by upper layers), specific sending of PDCP status reports can also be triggered. The additional trigger can be, for example, the first PDCP PDU and / or SDU is correctly received, or multiple PDCP PDUs and / or SDUs are correctly received. More generally, the conditions for triggering the sending of status reports can reuse any of the above-mentioned embodiments or conditions. Note that if a specific new trigger for sending a PDCP status report is used and new fields are defined in the status report, in one embodiment, the conditions for these two may be different. In another embodiment, those conditions may be the same (i.e., the conditions for triggering the sending of a PDCP status report may reflect the information provided by some fields).

[0073] For the transmitting side, successful delivery of a PDCP data PDU is acknowledged by one of the associated Acknowledged Mode (AM) RLC entities.

[0074] Resources leading to successful radio link control (RLC) reception

[0075] Successful RLC reception may include successful reception of one or more RLC service data units (SDU), one or more RLC SDU segments and / or one or more RLC protocol data units (PDU). For example, for a receiving UE, successful RLC reception may include sending a positive confirmation for an RLC SDU, an RLC SDU segment and / or an RLC PDU. This may rely on sending a status PDU (status report) carrying this information. For a transmitting UE, successful RLC reception may include receiving a positive confirmation for an RLC SDU, an RLC SDU segment and / or an RLC PDU from a peer RLC entity. This may rely on receiving a status PDU carrying this information. In some embodiments, more than one positive confirmation may be considered and may include, for example, a predetermined number of positive confirmations or a predetermined number of positive confirmations within a predetermined time period.

[0076] In another embodiment, successful reception can be inferred by the absence of RLC reception failure. For the receiving UE, this can include the absence of a determined negative acknowledgment or the absence of a sent negative acknowledgment for the RLC PDU, RLC SDU and / or RLC SDU segment. This can also include the absence of a status PDU carrying a negative acknowledgment. For the transmitting UE, successful reception can be inferred based on the absence of a negative acknowledgment received from the peer RLC entity. This can include the absence of a status PDU carrying a negative acknowledgment. In some embodiments, the determination of the absence of RLC reception failure can be performed within a predetermined time period and / or can depend on a threshold. For example, the threshold can be less than a predetermined number of negative acknowledgments determined and / or received. As another example, successful reception can be based on a threshold value less than a predetermined number of negative acknowledgments determined and / or received within a predetermined time period.

[0077] In other embodiments, the condition for successful reception may be inferred by the absence of a detected reception failure of a PDU (e.g., an Acknowledged Mode Data (AMD) PDU) and / or SDU. In other embodiments, more than zero detection failures may be considered. For example, successful reception may be determined if less than a predetermined number of reception failures are detected. The determination of detecting a reception failure (one or more) may be performed within a predetermined time period.

[0078] In another embodiment, detecting successful reception may include detecting no RLC SDU segments and / or no RLC PDU loss at the lower layer. In another embodiment, detecting successful reception may include detecting less than a predetermined number of (one or more) RLC SDU segments and / or (one or more) RLC PDU loss at the lower layer. Any of (one or more) of those determinations may be performed at a predetermined time period.

[0079] In another embodiment, "success" may be determined as successful delivery of a PDU (or upper layer PDU) or successful delivery of multiple PDUs (or upper layer PDUs). Any of those determinations (one or more) may be performed at predetermined time periods.

[0080] In another embodiment, "success" may be determined as the absence of an RLC PDU, RLC data PDU, or RLC SDU detected as lost by the receiving side, or less than a predetermined number of (one or more) RLC data PDUs, (one or more) RLC PDUs, and / or (one or more) RLC SDUs detected as lost by the receiving side. The determination of (one or more) RLC data PDUs, (one or more) RLC PDUs, and / or (one or more) RLC SDUs detected as lost may be performed within a predetermined time period.

[0081] For any of the above cases, the RLC entity may poll its peer AM RLC entity to trigger status reporting at the peer RLC entity.

[0082] For any of the above situations, 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 receiving RLC entity to notify the transmitting RLC entity of any of the above situations. One or more parameters defined under the status PDU may be reused for the above situations, or new parameters may be introduced for the above situations. These parameters may be, for example (as currently defined in the status PDU), an acknowledgment sequence number ACK_SN field (the sequence number of the next not received RLC SDU that is not reported as lost in the status PDU), a Data / Control (D / C) field, a Control PDU Type CPT, a negative acknowledgment sequence number NACK_SN (the sequence number of the RLC SDU or RLC SDU segment whose loss is detected by the receiving side), extension bits 1E1, extension bits E2, extension bits E3, a reserved field R, a SOstart field (the position in bytes of the first byte of the RLC SDU part in the original RLC SDU), a SOend field (the position in bytes of the last byte of this part of the RLC SDU in the original RLC SDU), and / or a NACK range field (the number of consecutive lost RLC SDUs starting from and including NACK_SN).

[0083] In another embodiment, "success" may be determined when a transmission opportunity is notified by a lower layer or when at least a predetermined number of transmission opportunities are notified by a lower layer. This may be determined within a predetermined time period.

[0084] In another embodiment, "success" may be determined as no errors corrected by Automatic Repeat Request (ARQ), less than a predetermined number of corrected errors, or less than a predetermined number of corrected errors within a predetermined time period.

[0085] In another embodiment, "success" may be determined as 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 period of time.

[0086] In another embodiment, "success" may be determined as no duplicate data being detected, less than a predetermined number of duplicate data being detected, or less than a predetermined number of duplicate data being detected within a period of time.Packet duplication of PDUs is defined for examples of NR and RLC in 3GPP TS 38.322.

[0087] In any of the above, the predetermined number and / or the predetermined time period may be defined in a standard (e.g., 3GPP TS 38.322 Radio Link Control), or may be configured or preconfigured in the UE. For example, the predetermined number and / or the predetermined time period may be configured (communicated) to the UE by the network (e.g., by the gNB via RRC signaling), by another UE via a PC5 interface, or preconfigured in the UE.

[0088] Resources leading to successful medium access control (MAC) reception

[0089] In some embodiments, the resources resulting in successful MAC reception may include resources in terms of time and / or frequency resulting in a successful HARQ ACK (positive acknowledgement) for a MAC PDU, MAC sub-PDU, and / or MAC SDU. Instead of a successful HARQ ACK, a predetermined number of ACKs may be used. This may be determined within a predetermined time period.

[0090] In another embodiment, "success" may be determined as no errors corrected by automatic repeat request (ARQ) or less than a predetermined number of errors corrected by ARQ. This may be determined within a predetermined time period.

[0091] In another embodiment, "success" may be determined if a transport block (TB) of data is successfully decoded, if a predetermined number of TBs of data are successfully decoded, or if at least a predetermined number of TBs of data are successfully decoded. This may be determined within a predetermined time period.

[0092] In another embodiment, if the decoded MAC PDU is delivered to the upper layer and / or RLC decomposition and demultiplexing entity, it can be determined as "successful". The determination can be based on a predetermined number of MAC PDUs. The determination can be applied within a predetermined time period.

[0093] In another embodiment, if the RLC indicates that the physical layer has generated (one or more) acknowledgements for data in a TB or a predetermined number of TBs, it may be determined to be "successful." This determination may be applicable within a predetermined period of time.

[0094] In another embodiment, "success" may be determined if the MAC entity receives no retransmissions for a TB or other resource, if the MAC entity receives less than a predetermined number (one or more) of retransmissions for a TB or other resource, or if the MAC entity does not receive a predetermined number of retransmissions for a TB or other resource. This determination may apply within a predetermined time period. Symmetrically, for the transmitting entity, "success" may be determined based on the absence of a retransmission (rather than the absence of a received retransmission).

[0095] In another embodiment, if the random access procedure is successfully completed or if less than a predetermined number of (one or more) random access procedures are successfully completed, it may be determined as "successful." The determination may be applied within a predetermined time period.

[0096] In another embodiment, "success" can be determined if no LBT failure indication is received at the MAC layer from (one or more) lower layers, if less than a predetermined number of (one or more) LBT failure indications are received from (one or more) lower layers, if no consistent LBT failure is determined (or triggered) at the MAC layer, or if less than a predetermined number of (one or more) 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 possibly less than a predetermined number of LBT failure MAC CEs or any LBT failure MAC CE). The conditions used for determination in any of those embodiments may be applied within a predetermined time period. As an alternative or supplement to the foregoing, the protocol data unit (PDU) LBT failure MAC CE defined in subclause 6.1.3.30 of 3GPPTS 38.321 (NR MAC protocol) may be used, including any of its already existing (one or more) fields (C0 to C24), or relying on new fields. In another embodiment, a new PDU format may be defined for this information.

[0097] In another embodiment, if there is a MAC transmission opportunity, if there is a predetermined number of MAC transmission opportunities, or if there is more than a predetermined number of MAC transmission opportunities, it may be determined as "successful." This determination may be applied within a predetermined period of time.

[0098] In another embodiment, 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, it may be determined as "successful". The determination may be applied within a predetermined time period.

[0099] In another embodiment, if no beam failure is detected, or if less than a predetermined number of beam failures (one or more) are detected, it may be determined to be "successful". The determination may be applied 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).

[0100] In another embodiment, "success" may be determined in the case of a successful contention resolution or in the case of more than a predetermined number (one or more) of successful contention resolutions. The determination may be applicable within a predetermined time period.

[0101] Other criteria used to determine "success" may include:

[0102] Indicates a positive acknowledgement that the physical layer may have generated data in a particular TB and / or other resource.

[0103] Instructs the physical layer to generate a positive acknowledgement corresponding to a transmission on one or more specific channels, such as the PUCCH (Physical Uplink Control Channel).

[0104] Acknowledgements corresponding to transmissions on any channel (eg, PSSCH) are obtained from the physical layer.

[0105] Receive and / or send (eg, for a sidelink process) an acknowledgement (positive ACK) to the corresponding sidelink HARQ entity.

[0106] The HARQ buffer (eg, of the associated sidelink process) is flushed or not.

[0107] Send and / or receive positive acknowledgements for the transmission of MAC PDUs.

[0108] Other conditions for determining "success" may be inferred by the absence of one or more of the following:

[0109] Instructs the physical layer to possibly generate a negative acknowledgement of data in a particular TB and / or other resources.

[0110] Instructs the physical layer to generate a negative acknowledgement corresponding to a transmission on one or more specific channels (eg, PUCCH).

[0111] A radio link failure is detected, such as a HARQ-based sidelink radio link failure. In some embodiments, this may be based on the number of consecutive discontinuous transmissions (DTX) on a PSFCH (Physical Sidelink Feedback Channel) reception opportunity for a PC5-RRC connection, or may be applied to each PSFCH reception opportunity associated with a PSSCH transmission, as described in 3GPP TS 38.321.

[0112] Receive and / or send a negative acknowledgement to the corresponding sidelink HARQ entity (e.g., for a sidelink process).

[0113] The HARQ buffer (eg, of the associated sidelink process) is flushed or not.

[0114] If negative acknowledgment-only is enabled in the SCI or if positive-negative acknowledgment is enabled, a negative acknowledgment for the transmission of a MAC PDU may be sent and / or received.

[0115] A HARQ retransmission has arrived, possibly selected by the MAC entity.

[0116] Resources that lead to successful IP packet reception

[0117] For successful IP packet reception, the transmitting UE may send a predetermined field, keyword or parameter value to the receiving party (possibly in a message, in a new or already existing message). The receiving party may reply to the transmitting UE with another predetermined field (which may be the same field). A timer may be used on the application side, and the absence of a reply within a predetermined period of time may be determined as a failure (i.e., absence of success).

[0118] The resources that lead to successful physical layer connection and / or reception

[0119] The criteria used to determine "success" may include one or more of the following:

[0120] The physical layer is instructed by the MAC layer to generate a positive acknowledgement of the data, possibly for a specific resource, such as a TB.

[0121] The physical random access procedure is successful / completed.

[0122] HARQ-Ack (ACK value) is determined or reported at the physical layer, for example, sidelink HARQ-Ack.

[0123] The conditions for determining "success" may be inferred by the absence of one or more of the following:

[0124] The MAC layer instructs the physical layer to generate a negative acknowledgement of the data (e.g., sidelink HARQ-Nack), possibly for a specific resource, such as a TB.

[0125] Resources leading to successful PC5-RRC (Radio Resource Control) connection and / or reception

[0126] The criteria used to determine "success" may include one or more of the following:

[0127] The RRC connection establishment of the sidelink is successful, for example, receiving or sending an RRC Setup message.

[0128] An RRCReconfigurationCompleteSidelink message is received or sent.

[0129] The conditions for determining "success" may be inferred by the absence of one or more of the following:

[0130] The RRC connection establishment of the sidelink is unsuccessful, for example, an RRC Reject is received or sent.

[0131] A sidelink Radio Link Failure (RLF) was detected.

[0132] An indication is received from a sidelink RLC entity that a maximum number of retransmissions has been reached, e.g., for a particular destination.

[0133] An indication is received from the MAC entity that a maximum number of consecutive HARQ DTXs has been reached, e.g., for a particular destination.

[0134] Timer T400 (started when RRCReconfigurationSidelink is sent and stopped when RRCReconfigurationFailureSidelink / RRCReconfigurationCompleteSidelink is received) expires, for example, for a specific destination.

[0135] The RRC indicates the release of the PC5-RRC connection to the upper layer for the specific destination (ie, PC5 is not available).

[0136] An RRC reconfiguration failure sidelink (RRCReconfigurationFailureSidelink) message is received or sent.

[0137] For the example of NR, this may rely on the Radio Resource Control (RRC) NR protocol.

[0138] In any of the (one or more) schemes of the present disclosure, the determination may be based on more than one instance of a particular condition (and / or more than one instance with another condition). The logical functions "OR", "XOR" or "AND" may be used. The determination may be applied within a predetermined time period. For example, an "erase timer" may be used. In another (possibly complementary) embodiment, the determination may depend on a continuous condition. The schemes described in the present disclosure may be controlled by a timer and / or a disabling procedure, after which the scheme is disabled after a specific time period (i.e., reverting to the traditional process of random sensing and / or not using information about success), and / or after access / communication is unsuccessful (e.g., more than a specific number of times or more than a specific number of times within a predetermined time period).

[0139] (One or more) above-mentioned proposed schemes can be used particularly by UEs that are in close proximity and / or traveling at equivalent speeds or near equivalent speeds. Another possible embodiment is that any embodiment in the present disclosure is only applied to UEs that are in close proximity, and / or traveling at equivalent speeds or near equivalent speeds, and / or traveling in the same direction.

[0140] In another embodiment, any embodiment described in this disclosure may be conditionally applied to a UE in a sidelink coexistence setting.

[0141] Although the examples provided in the present disclosure relate to 3GPP NR (New Radio), the embodiments in the present disclosure are not limited to this Radio Access Technology (RAT) and can be applied to other RATs, such as LTE / E-UTRA and / or 6G. Although the examples provided in the present disclosure relate to 3GPP sidelink, the embodiments in the present disclosure are not limited to 3GPP and can be applied 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.

[0142] User Equipment (UE)

[0143] Figure 2 is a block diagram of a UE 200 consistent with some embodiments of the present disclosure. The UE 200 may be installed in a moving vehicle, at a fixed location (e.g., as a roadside unit (RSU)), or may be carried by a person. The UE 200 may take any form, including but not limited to a vehicle, a component installed in a vehicle, an RSU, a laptop computer, a wireless terminal including a mobile phone, a wireless handheld device, a wireless personal device, or any other form. Figure 2UE 200 may include an antenna 202, which may be used to transmit electromagnetic signals to a base station or other UEs and / or receive electromagnetic signals from a base station or other UEs. Antenna 202 may include one or more antenna elements and may implement different input-output antenna configurations, such as 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, antenna 202 may include multiple (e.g., tens or hundreds) of antenna elements and may implement multi-antenna functions, such as beamforming. In some embodiments, antenna 202 is a single antenna.

[0144] UE 200 may include a transceiver 204 coupled to antenna 202. Transceiver 204 may be a wireless transceiver at UE 200 and may communicate bidirectionally with a base station or other UEs. For example, transceiver 204 may receive wireless signals from a base station via a downlink and transmit wireless signals to a base station via an uplink communication. Transceiver 204 may also receive wireless signals from another UE or roadside unit (RSU) via a sidelink communication and transmit wireless signals to another UE or roadside unit (RSU). Transceiver 204 may include a modem that modulates packets and provides the modulated packets to antenna 202 for transmission, and demodulates packets received from antenna 202.

[0145] UE 200 may include memory 206. Memory 206 may be any type of computer-readable storage medium, including volatile or non-volatile memory devices or combinations thereof. Computer-readable storage media include, but are not limited to, non-transitory computer storage media. Non-transitory storage media may be accessed by general-purpose or special-purpose computers. Examples of non-transitory storage media include, but are not limited to, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM), electrically erasable programmable ROM (EEPROM), digital versatile disks (DVD), flash memory, compact disks (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, etc. Non-transitory media may be used to carry or store desired program code devices (e.g., instructions and / or data structures), and may be accessed by general-purpose or special-purpose computers or general-purpose or special-purpose processors. In some examples, the software / program code may be transmitted from a remote source (e.g., a website, a server, etc.) using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves. In such examples, coaxial cables, fiber optic cables, twisted pairs, DSL, or wireless technologies such as infrared, radio, and microwaves are within the scope of the definition of the medium. Combinations of the above examples are also within the scope of computer-readable media.

[0146] The memory 206 may store information related to the identification of the UE 200 and the 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 also store computer-readable program instructions for execution by the processor 208 to operate the UE 200 to perform different functions described elsewhere in this disclosure. In some examples, the memory 206 may include a basic input / output system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0147] The computer-readable program instructions of the present disclosure can be assembly instructions, instruction set architecture (Instruction-Set-Architecture, ISA) instructions, machine instructions, machine-related 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 traditional process programming languages). The computer-readable program instructions can be executed completely on a computing device as an independent software package, or partially on a first computing device and partially on a second computing device away from the first computing device. In the latter case, the second remote computing device can be connected to the first computing device through any type of network (including a local area network (Local Area Network, LAN) or a wide area network (Wide Area Network, WAN)).

[0148] UE 200 may include a processor 208, which may include a hardware device with processing capabilities. 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 other programmable logic devices. Examples of general-purpose processors include, but are not limited to, microprocessors, any conventional processors, controllers, microcontrollers, or state machines. In some embodiments, 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). Processor 208 may receive a downlink signal or a sidelink signal from transceiver 204 and further process the signal. Processor 208 may also receive a packet from transceiver 204 and further process the packet. 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 enable the UE 200 to perform different functions.

[0149] UE 200 may include a global positioning system (GPS) 210. GPS 210 may be used to implement location-based services or other services based on the geographic location of UE 200, and / or for synchronization between UEs. GPS 210 may receive a global navigation satellite system (GNSS) signal from a single satellite or multiple satellite signals via antenna 202 and provide the geographic location of UE 200 (e.g., coordinates of UE 200).

[0150] UE 200 may include an input / output (I / O) device 212, which may be used to communicate the results of signal processing and calculation to a user or another device. I / O device 212 may include a user interface, which includes a display and an input device for transmitting user commands to processor 208. The display may be configured to display the state of signal reception at UE 200, the data stored at memory 206, the state of signal processing and the results of calculation, etc. The display may include, but is not limited to, a cathode ray tube (Cathode Ray Tube, CRT), a liquid crystal display (Liquid Crystal Display, LCD), a light-emitting diode (Light-Emitting Diode, LED), a gas plasma display, a touch screen or other image projection devices for displaying information to a user. The input device may be any type of computer hardware device for receiving data and control signals from a user. The input device may include, but is not limited to, a keyboard, a mouse, a scanner, a digital camera, a joystick, a trackball, a cursor direction key, a touch screen monitor or an audio / video commander, etc.

[0151] UE 200 may further include a machine interface 214 , such as an electrical bus that connects transceiver 204 , memory 206 , processor 208 , GPS 210 , and I / O devices 212 .

[0152] 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 a sidelink radio resource by the UE 200, for example, in conjunction with Figure 1 The method 100 is described.

[0153] As used in this disclosure, the use of the term "or" in a list of items indicates an inclusive list. A list of items may be prefixed with phrases 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). In addition, as used in this disclosure, prefixing a list of conditions with the phrase "based on" should not be interpreted as "based only on" a set of conditions, but rather should be interpreted as "based at least in part on" a set of conditions. For example, a result described as "based on condition A" may be based on both condition A and condition B without departing from the scope of this disclosure.

[0154] In this specification, the terms "include", "contain" or "comprises" are used interchangeably and have the same meaning and are interpreted as inclusive and open-ended. The terms "include", "contain" or "comprises" may be used before a list of elements and indicate that at least all of the listed elements in the list are present, but other elements that are not in the list may also be present. For example, if A includes B and C, then {B, C} and {B, C, D} are both within the scope of A.

[0155] In conjunction with the accompanying drawings, the present disclosure describes example configurations that do not represent all examples that can be implemented or all configurations within the scope of the present disclosure. The term "exemplary" should not be interpreted as "preferred" or "advantageous compared to other examples", but should be interpreted as "illustration, instance, or example". By reading this disclosure, including the description of the embodiments and the accompanying drawings, a person of ordinary skill in the art will understand that alternative embodiments can be used to implement the technology disclosed herein. Those skilled in the art will understand that the embodiments described herein or certain features of the embodiments can be combined to obtain other embodiments for practicing the technology described in the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

[0156] The flowcharts and block diagrams in the accompanying drawings illustrate examples of possible architectures, functions, and operations of systems, methods, and devices according to various embodiments. It should be noted that in some alternative implementations, the functions marked in the boxes may occur outside the order marked in the figure. For example, depending on the functions involved, the two boxes shown in succession may actually be executed substantially simultaneously, or the boxes may sometimes be executed in reverse order. Similarly, in methods that conform to various embodiments, additional steps may be included in such methods, and some steps may be omitted or combined.

[0157] It should be understood that the described embodiments are not mutually exclusive, and elements, components, materials or steps described in conjunction with one exemplary embodiment may be combined with or eliminated from other embodiments in a suitable manner to achieve the desired design goals.

[0158] References herein to "some embodiments" or "some exemplary embodiments" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment. The appearance of the phrases "one embodiment," "some embodiments," or "another embodiment" throughout this disclosure does not necessarily refer to the same embodiment, nor are they necessarily separate or alternative embodiments that are mutually exclusive with other embodiments.

[0159] In addition, the articles "a" and "an" as used in this disclosure and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clearly directed to a singular form by context.

[0160] Unless expressly stated otherwise, each numerical value and range should be interpreted as being approximate, as would the word "about" or "approximately" preceding the value of the numerical value or range.

[0161] Although elements in the following method claims, if any, are recited in a specific order, these elements are not necessarily intended to be limited to being implemented in that specific order unless the claim recitation otherwise implies a specific order for implementing some or all of these elements.

[0162] It should be understood that certain features of the present disclosure described in the context of separate embodiments for the sake of clarity may also be provided in combination in a single embodiment. Conversely, various features of the present specification described in the context of a single embodiment for the sake of brevity may also be provided separately, or in any suitable sub-combination, or as appropriate in any other described embodiment of the present specification. Certain features described in the context of various embodiments are not essential features of these embodiments unless otherwise stated.

[0163] It will be further understood that those skilled in the art may make various modifications, substitutions and changes to the details, materials and arrangements of the components described and illustrated for the purpose of explaining the nature of the described embodiments without departing from the scope of the present disclosure. Accordingly, the appended claims cover all such substitutions, modifications and changes falling within the aspects of the claims.

[0164] Clause 1. A method for selecting a sidelink radio resource by a user equipment (UE), comprising: transmitting from the UE to one or more recipients on the selected radio resources; determining whether the UE successfully transmits on the selected radio resources; Based on a determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; and In the next transmission opportunity of the UE, transmission on the preferred radio resources is prioritized.

[0165] Clause 2. The method according to clause 1, further comprising: A radio resource is selected from the resource pool as the selected radio resource.

[0166] Clause 3. The method of clause 2, wherein the resource pool is provided to the UE by configuration or pre-configuration.

[0167] Clause 4. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises: determining whether the selected radio resource is available after sensing of one or more radio resources.

[0168] Clause 5. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that there was no conflict on the selected radio resource during the transmission.

[0169] Clause 6. The method of clause 5, wherein the absence of a collision is determined based on the absence of a collision being detected within a predetermined time period after the transmission.

[0170] Clause 7. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource is determined based on replies received from one or more recipients within a predetermined time period after the transmission.

[0171] Clause 8. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that there was a previous successful reception from the UE on the selected radio resource by one or more recipients.

[0172] Clause 9. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining receipt of a hybrid automatic repeat request acknowledgement for the transmission.

[0173] Clause 10. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that a hybrid automatic repeat request negative acknowledgement for the transmission was not received within a predetermined time period.

[0174] Clause 11. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in a successful radio link control reception.

[0175] Clause 12. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in a successful radio link control service data unit reception.

[0176] Clause 13. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in successful radio link control service data unit segment reception.

[0177] Clause 14. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resource comprises determining that the transmission resulted in successful radio link control protocol data unit reception.

[0178] Clause 15. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in successful medium access control reception.

[0179] Clause 16. The method of clause 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 acknowledgements.

[0180] Clause 17. The method of clause 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 acknowledgements within a predetermined time period.

[0181] Clause 18. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in successful Internet Protocol packet reception.

[0182] Clause 19. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in a successful physical layer connection.

[0183] Clause 20. The method of clause 1, wherein determining whether the UE successfully transmitted on the selected radio resources comprises determining that the transmission resulted in successful physical layer reception.

[0184] Clause 21. The method of clause 20, wherein the successful physical layer reception is on a physical uplink control channel.

[0185] Clause 22. The method of clause 20, wherein the successful physical layer reception is on a physical sidelink shared channel.

[0186] Clause 23. The method of clause 1, wherein determining whether the UE successfully transmitted is based on using random resource selection.

[0187] Clause 24. The method of clause 23, wherein the preferred radio resource has a higher probability than one or more other radio resources.

[0188] Clause 25. The method of clause 1, wherein identifying the selected radio resource as a preferred radio resource comprises: After a predetermined number of successful transmissions using the selected radio resource, the selected radio resource is identified as a preferred radio resource.

[0189] Clause 26. The method of clause 1, wherein identifying the selected radio resource as a preferred radio resource comprises: After a predetermined number of successful transmissions using the selected radio resource within a predetermined time period, the selected radio resource is identified as a preferred radio resource.

[0190] Clause 27. The method according to Clause 1, further comprising: selecting a preferred radio resource based on sensing of one or more radio resources; and Transmit on preferred radio resources.

[0191] Clause 28. The method according to clause 1, further comprising: An identifier of the preferred radio resource is stored in a memory of the UE.

[0192] Clause 29. A method for selecting a sidelink radio resource by a user equipment (UE), the UE comprising: a memory configured to store instructions; and a processor configured to execute instructions stored in the memory to: transmitting from the UE to one or more recipients on the selected radio resources; determining whether the UE successfully transmits on the selected radio resources; Based on a determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; and In the next transmission opportunity of the UE, transmission on the preferred radio resources is prioritized.

[0193] Clause 30. A UE according to clause 29, wherein the processor is further configured to: A radio resource is selected from the resource pool as the selected radio resource.

[0194] Clause 31. The UE of clause 30, wherein the resource pool is provided to the UE by configuration or pre-configuration.

[0195] Clause 32. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmits on the selected radio resource by determining whether the selected radio resource is available after sensing the one or more radio resources.

[0196] Clause 33. 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 no conflict on the selected radio resource during the transmission.

[0197] Clause 34. The UE of clause 33, wherein the absence of a collision is determined based on not detecting a collision within a predetermined time period after the transmission.

[0198] Clause 35. A UE according to clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource based on replies received from one or more recipients within a predetermined time period after the transmission.

[0199] Clause 36. A UE according to 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 a previous successful reception from the UE on the selected radio resource by one or more recipients.

[0200] 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 a hybrid automatic repeat request acknowledgement for the transmission was received.

[0201] Clause 38. A UE according to clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resource by determining that a hybrid automatic repeat request negative acknowledgement for the transmission was not received within a predetermined time period.

[0202] 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 a successful radio link control reception.

[0203] Clause 40. 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 successful radio link control service data unit reception.

[0204] Clause 41. 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 successful radio link control service data unit segment reception.

[0205] Clause 42. 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 successful radio link control protocol data unit reception.

[0206] Clause 43. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resources by determining that the transmission resulted in successful medium access control reception.

[0207] 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 acknowledgements.

[0208] Clause 45. 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 within a predetermined time period.

[0209] Clause 46. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resources by determining that the transmission resulted in successful Internet Protocol packet reception.

[0210] Clause 47. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resources by determining that the transmission resulted in a successful physical layer connection.

[0211] Clause 48. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted on the selected radio resources by determining that the transmission resulted in successful physical layer reception.

[0212] Clause 49. The UE of clause 48, wherein the successful physical layer reception is on a physical uplink control channel.

[0213] Clause 50. The UE of clause 48, wherein the successful physical layer reception is on a physical sidelink shared channel.

[0214] Clause 51. The UE of clause 29, wherein the processor is further configured to determine whether the UE successfully transmitted based on using random resource selection.

[0215] Clause 52. The UE of clause 51, wherein the preferred radio resource has a higher probability than one or more other radio resources.

[0216] 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.

[0217] Clause 54. 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 within a predetermined time period.

[0218] Clause 55. A UE according to clause 29, wherein the processor is further configured to: selecting a preferred radio resource based on sensing of one or more radio resources; and Transmit on preferred radio resources.

[0219] Clause 56. A UE according to clause 29, wherein the processor is further configured to: An identifier of the preferred radio resource is stored in a memory.

[0220] Clause 57. A non-transitory computer-readable medium storing instructions executable by one or more processors of a user equipment (UE) in a communication network to perform a method, the method comprising: transmitting from the UE to one or more recipients on the selected radio resources; determining whether the UE successfully transmits on the selected radio resources; Based on a determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; and In the next transmission opportunity of the UE, transmission on the preferred radio resources is prioritized.

Claims

1. A method for selecting a sidelink radio resource by a user equipment (UE), comprising: transmitting from the UE to one or more recipients on the selected radio resources; determining whether the UE successfully transmits on the selected radio resource; Based on a determination that the UE successfully transmitted on the selected radio resource, identifying the selected radio resource as a preferred radio resource; as well as In a next transmission opportunity of the UE, transmission is preferentially performed on the preferred radio resource.

2. The method according to claim 1, wherein: Determining whether the UE successfully transmits on the selected radio resource includes determining whether the selected radio resource is available after sensing one or more radio resources.

3. The method according to claim 1, wherein: Determining whether the UE successfully transmits on the selected radio resource includes determining that there is no conflict on the selected radio resource during transmission.

4. The method according to claim 1, wherein: Determining whether the UE successfully transmits on the selected radio resource is based on receiving a reply from the one or more recipients within a predetermined time period after the transmission.

5. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that there was a previous successful reception from the UE on the selected radio resource by the one or more recipients.

6. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining receipt of a hybrid automatic repeat request acknowledgment for the transmission.

7. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that a hybrid automatic repeat request negative acknowledgement for the transmission is not received within a predetermined time period.

8. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in a successful radio link control reception.

9. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in successful radio link control service data unit reception.

10. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in successful radio link control service data unit segment reception.

11. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in successful radio link control protocol data unit reception.

12. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resources includes determining that the transmission resulted in successful medium access control reception.

13. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgements.

14. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in a predetermined number of hybrid automatic repeat request acknowledgements within a predetermined time period.

15. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resource includes determining that the transmission resulted in successful Internet Protocol packet reception.

16. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resources includes determining that the transmission resulted in a successful physical layer connection.

17. The method according to claim 1, wherein: Determining whether the UE successfully transmitted on the selected radio resources includes determining that the transmission resulted in successful physical layer reception.

18. The method according to claim 1, wherein: Identifying the selected radio resource as a preferred radio resource comprises: After a predetermined number of successful transmissions using the selected radio resource, the selected radio resource is identified as the preferred radio resource.

19. The method according to claim 1, wherein: Identifying the selected radio resource as a preferred radio resource comprises: After a predetermined number of successful transmissions using the selected radio resource within a predetermined time period, the selected radio resource is identified as the preferred radio resource.

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

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