Methods, devices and systems for sidelink resource selection

Abstract

The present disclosure above describes methods, devices, and systems for sidelink communications. The method, performed by a first UE, includes initiating a sidelink data transmission session with a second UE awake in DRX mode and selecting a first transmission resource for transmitting a first data packet of the sidelink data transmission session to the second UE during a first active time of the second UE. The present disclosure describes various embodiments that support sidelink transmission resource selection in DRX mode, sidelink transmission resource selection / reselection, inter-UE cooperation for transmission resource selection, logical channel prioritization, and assistance information reporting over shared transmission resources, etc.

Description

[Technical Field]

[0001] The present disclosure is directed generally to wireless communications, and more particularly to methods, systems, and devices for sidelink communications. [Background technology]

[0002] With the development of wireless multimedia services, the demand for high data rates and user experience is increasing, which leads to higher requirements for the capacity and coverage of wireless communication systems. Meanwhile, application scenarios such as public safety, social networking, short-distance data sharing, and local advertising are gradually increasing the demand for communication between nearby devices. Therefore, device-to-device (D2D) communication technology has emerged. D2D technology can reduce the burden on cellular networks, reduce the battery power consumption of user equipment (UE), increase data rates, and improve the robustness of network infrastructure, which meets the requirements of high-data-rate services and proximity services. D2D technology is also referred to as proximity service (ProSe) or sidelink (SL) communication.

[0003] Reducing the power consumption and extending the battery life of mobile devices are important goals when designing sidelink communication. Reducing the operation time of the UE hardware circuitry in sidelink communication while still meeting service requirements can significantly contribute to such power savings. Summary of the Invention [Means for solving the problem]

[0004] The present disclosure is directed to methods, systems, and devices for sidelink communications.

[0005] In one embodiment, a method for sidelink communication in a wireless communication network is disclosed. The method, performed by a first UE, may include initiating a sidelink data transmission session with a second UE operating in a discontinuous reception (DRX) mode and selecting, during a first active time of the second UE, first transmission resources for transmitting a first data packet of the sidelink data transmission session to the second UE.

[0006] In one embodiment, a method for sidelink communication in a wireless communication network is disclosed. The method, performed by a first UE, may include initiating a sidelink data transmission session with a second UE operating in a DRX mode, the sidelink data transmission session being associated with a set of logical channels; determining a logical channel from the set of logical channels based on a predefined condition; and selecting transmission resources for the sidelink data transmission session based on the logical channel.

[0007] In one embodiment, a method for sidelink communication in a wireless communication network is disclosed, wherein the method, performed by a first UE configured with preselected transmission resources in a transmission resource pool for supporting sidelink data transmission to a second UE, may include determining that the preselected transmission resources are no longer suitable for the sidelink data transmission and updating the preselected transmission resources with transmission resources that are suitable for the sidelink data transmission.

[0008] In one embodiment, a method, performed by a UE, for performing logical channel prioritization in sidelink communications is disclosed, which may include determining that a destination UE is not in active time and that the destination UE is awake in DRX mode, and skipping logical channels associated with the destination UE when performing logical channel prioritization.

[0009] In one embodiment, a method for sidelink communication in a wireless communication network is disclosed. The method, performed by a first UE, may include initiating inter-UE cooperation with a second UE in response to at least one of the following conditions being satisfied: a priority or reliability requirement for sidelink data to be transmitted is higher than a preconfigured threshold; a channel busy rate of the first UE is higher than a preconfigured threshold; a number of discontinuous transmissions to the second UE is higher than a preconfigured threshold; a number of Hybrid Automatic Repeat Request Negative Acknowledgments (HARQ NACKs) received from the second UE is higher than a preconfigured threshold; the second UE supports inter-UE cooperation; a set of transmission resources for sidelink communication provided by the second UE is outdated; a transmission resource pool for sidelink communication has been reconfigured; sensing parameters of the first UE have been reconfigured; or none of the transmission resources in the set of transmission resources for sidelink communication provided by the second UE is capable of accommodating a maximum allowed modulation and coding scheme.

[0010] In one embodiment, a method for selecting a second UE as a destination UE during a logical channel prioritization procedure in sidelink communication, performed by a first UE configured with transmission resources for sidelink data transmission, is disclosed, the method may include at least one of: selecting the second UE as the destination UE in response to the transmission resources being within a set of preferred resources provided by the second UE; selecting the second UE as the destination UE in response to the transmission resources being not included in a set of non-preferred resources provided by the second UE; or selecting the second UE as the destination UE in response to the transmission resources being not included in a set of conflicting resources provided by the second UE.

[0011] In one embodiment, a method for sidelink communication in a wireless communication network is disclosed. The method, performed by a first UE, may include determining, during a logical channel prioritization procedure for sidelink communication, that sufficient capacity exists in sidelink data transmission resources after data multiplexing; adding a transmission resource report to the sidelink data transmission resources, where the transmission resource report is used to assist a second UE for selecting sidelink data transmission resources; and transmitting the sidelink data transmission resources to the second UE.

[0012] In some embodiments, a wireless communication device is disclosed comprising a processor and a memory, wherein the processor is configured to read code from the memory and implement any method described in any of the embodiments.

[0013] In some embodiments, a computer program product is disclosed comprising a computer readable medium code stored thereon, the code, when executed by a processor, causing the processor to implement any method described in any of the embodiments.

[0014] Other aspects and alternatives of the above embodiments and their implementations are described in more detail in the following drawings, description, and claims. The present invention provides, for example, the following. (Item 1) 1. A method for sidelink communication in a wireless communication network, performed by a first UE, comprising: initiating a sidelink data transmission session with a second UE operating in a discontinuous reception (DRX) mode; selecting a first transmission resource for transmitting a first data packet of the sidelink data transmission session to the second UE during a first active time of the second UE; A method comprising: (Item 2) Item 1. The method of item 1, further comprising selecting, during a second active time of the second UE, second transmission resources for transmitting subsequent data packets of the sidelink data transmission session to the second UE. (Item 3) configuring a sidelink data transmission session with a periodicity t1, where t1 is less than or equal to a duration of an inactivity timer managed by the second UE, the inactivity timer being reset by the second UE in response to receiving a subsequent data packet for the sidelink data transmission session; Item 1, the method of claim 1 further comprising: (Item 4) Item 1. The method of item 1, wherein the first UE is running in a DRX mode. (Item 5) configuring a first logical channel configuration to support a first sidelink data transmission to a first destination UE operating in DRX mode; configuring a second logical channel configuration to support a second sidelink data transmission to a second destination UE not operating in DRX mode; Item 5. The method according to item 4, further comprising: (Item 6) Selecting the first transmission resource comprises: selecting, during the first active time of the second UE, the first transmission resource for transmitting a first data packet of the sidelink data transmission session to the second UE in accordance with a DRX configuration of the second UE. Item 1. The method according to item 1, comprising: (Item 7) 1. A method for sidelink communication in a wireless communication network, performed by a first UE, comprising: initiating a sidelink data transmission session with a second UE operating in DRX mode, the sidelink data transmission session being associated with a set of logical channels; and determining a logical channel from the set of logical channels based on a predefined condition; selecting transmission resources for the sidelink data transmission session based on the logical channel; and A method comprising: (Item 8) The predefined condition is: the logical channel having the highest priority among all logical channels in the set of logical channels having sidelink data available for transmission, or the logical channel having the highest priority among all logical channels in the set of logical channels having a sidelink bucket size greater than 0. Item 8. The method according to item 7, comprising one of the following: (Item 9) 1. A method for sidelink communication in a wireless communication network, performed by a first UE configured with preselected transmission resources in a transmission resource pool to support sidelink data transmission to a second UE, the method comprising: determining that the preselected transmission resources are no longer suitable for sidelink data transmission; and updating the preselected transmission resources with transmission resources that are suitable for sidelink data transmission; and A method comprising: (Item 10) determining that the preselected transmission resources are no longer suitable for sidelink data transmission; determining, in response to the preselected transmission resource not being within an active time of the second UE, that the preselected transmission resource is no longer suitable for the sidelink data transmission. Item 10. The method according to item 9, comprising: (Item 11) Updating the preselected transmission resources comprises: triggering a sidelink transmission resource reselection procedure, or selecting the transmission resources suitable for the sidelink data transmission and replacing the preselected transmission resources with the transmission resources in a transmission resource pool maintained by the first UE. Item 10. The method according to item 9, comprising one of the following: (Item 12) 1. A method for implementing logical channel prioritization in sidelink communication performed by a UE, comprising: determining that a destination UE is not in an active time and that the destination UE is awake in a DRX mode; skipping a logical channel associated with the destination UE when performing the logical channel prioritization; A method comprising: (Item 13) 1. A method for sidelink communication in a wireless communication network, performed by a first UE, comprising: the priority or reliability requirement of the sidelink data to be transmitted is higher than a preconfigured threshold; a channel busy rate of the first UE is greater than a preconfigured threshold; the number of discontinuous transmissions to the second UE is greater than a preconfigured threshold; a number of Hybrid Automatic Repeat Request Negative Acknowledgments (HARQ NACKs) received from the second UE is greater than a preconfigured threshold; the second UE supports inter-UE cooperation; a set of transmission resources for sidelink communication provided by the second UE is outdated; a transmission resource pool for sidelink communication is reconfigured; the sensing parameters of the first UE are reconfigured; or that none of the transmission resources in the set of transmission resources for sidelink communication provided by the second UE is capable of accommodating the maximum allowed modulation and coding scheme. initiating inter-UE cooperation with the second UE in response to at least one of the conditions being satisfied. (Item 14) 1. A method for selecting a second UE as a destination UE during a logical channel prioritization procedure in sidelink communication, the method being performed by a first UE configured with transmission resources for sidelink data transmission, the method comprising: selecting the second UE as a destination UE in response to the transmission resource being within a set of preferred resources provided by the second UE; selecting the second UE as a destination UE in response to the transmission resource not being included in a set of non-preferred resources provided by the second UE; or selecting the second UE as a destination UE in response to the transmission resource not being included in a set of conflicting resources provided by the second UE; The method includes at least one of the following: (Item 15) 1. A method for sidelink communication in a wireless communication network, performed by a first UE, comprising: - determining, during a logical channel prioritization procedure for sidelink communication, that there is sufficient capacity in the sidelink data transmission resources after data multiplexing; adding a transmission resource report to the sidelink data transmission resources, the transmission resource report being used to assist the second UE for selecting sidelink data transmission resources; and transmitting the sidelink data transmission resource to the second UE; A method comprising: (Item 16) A device comprising one or more processors, wherein the one or more processors are configured to implement the method according to any one of items 1-15. (Item 17) 16. A computer program product comprising a non-transitory computer-readable program medium having computer code stored thereon, the computer code, when executed by one or more processors, causing the one or more processors to implement the method of any one of items 1-15. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 illustrates an exemplary wireless communication network. [Figure 2] FIG. 2 illustrates various exemplary sidelink communication scenarios. [Figure 3] FIG. 3 illustrates a receiving user equipment (RX UE) receiving sidelink data in discontinuous reception (DRX) mode. [Figure 4] FIG. 4 illustrates an exemplary transmission resource selection at a transmitting UE (TX UE) for transmitting sidelink data to a RX UE configured with an active timer. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following description and drawings describe in detail certain illustrative implementations of the present disclosure, which illustrate some exemplary ways in which various principles of the present disclosure may be practiced. However, the illustrated examples are not exhaustive of the many possible embodiments of the present disclosure. Other objects, advantages, and novel features of the present disclosure will also be set forth in the following detailed description when considered in conjunction with the drawings. Introduction

[0017] FIG. 1 shows an exemplary wireless communication network 100 including a core network 110 and a radio access network (RAN) 120. The core network 110 further includes at least one mobility management entity (MME) 112 and / or at least one access and mobility management function (AMF). Other functions that may be included in the core network 110 are not shown in FIG. 1. The RAN 120 further includes multiple base stations, e.g., base stations 122 and 124. The base stations may include at least one evolved NodeB (eNB) for 4G LTE, or a next-generation NodeB (gNB) for 5G new radio (NR), or any other type of signal transmission / reception device, such as a UMTS NodeB. The eNB 122 communicates with the MME 112 via an S1 interface. Both the eNB 122 and the gNB 124 may connect to the AMF 114 via an Ng interface. Each base station manages and supports at least one cell. For example, base station gNB124 may be configured to manage and support cell 1, cell 2, and cell 3.

[0018] The gNB 124 may further include a central unit (CU) and at least one distributed unit (DU). The CU and DU may be co-located, or they may be split into different locations. The CU and DU may be connected via an F1 interface. Alternatively, an eNB capable of connecting to a 5G network may also be similarly split into a CU and at least one DU, and may be referred to as an ng-eNB-CU and an ng-eNB-DU, respectively. The ng-eNB-CU and ng-eNB-DU may be connected via a W1 interface.

[0019] The wireless communication network 100 may include one or more tracking areas. A tracking area may include a set of cells managed by at least one base station. For example, tracking area 1, labeled 140, includes cell 1, cell 2, and cell 3 and may further include many more cells that may be managed by other base stations and are not shown in FIG. 1 . The wireless communication network 100 may also include at least one UE 160. The UE may select a cell from among multiple cells supported by the base station to communicate with the base station over an over-the-air (OTA) wireless communication interface and resources, and the UE 160 may reselect a cell for communication as it moves within the wireless communication network 100. For example, the UE 160 may initially select cell 1 to communicate with the base station 124 and then reselect cell 2 at some later point in time. The cell selection or reselection by the UE 160 may be based on wireless signal strength / quality in various cells and other factors.

[0020] The wireless communication network 100 may be implemented, for example, as a 2G, 3G, 4G / LTE, or 5G cellular communication network. Correspondingly, the base stations 122 and 124 may be implemented as 2G base stations, 3G NodeBs, LTE eNBs, or 5G NR gNBs. The UEs 160 may be implemented as mobile or fixed communication devices capable of accessing the wireless communication network 100. The UEs 160 may include, but are not limited to, mobile phones, laptop computers, tablets, personal digital assistants, wearable devices, Internet of Things (IoT) devices, MTC / eMTC devices, distributed remote sensor devices, roadside assistance equipment, and desktop computers. The UEs 160 may support sidelink communication to another UE via a PC5 interface.

[0021] Although the following description focuses on a cellular wireless communication system, as shown in Figure 1, the basic principles are applicable to other types of wireless communication systems for paging wireless devices. These other wireless systems may include, but are not limited to, Wi-Fi, Bluetooth, ZigBee, and WiMax networks. Sidelink communication

[0022] Sidelink communication is a communication mechanism that allows cellular devices, such as UEs, IoT devices, vehicles, and other types of wireless terminals, to communicate directly with each other without using the cellular network as an intermediary.

[0023] FIG. 2 illustrates various configurations for sidelink communication. Configuration 210 illustrates an "in-coverage" configuration in which both UE1 and UE2 are under cellular coverage. Configuration 212 illustrates a "partial coverage" configuration in which only UE1 is under cellular coverage. Configuration 214 illustrates an "out-of-coverage" configuration in which neither UE1 nor UE2 is under cellular coverage. As shown in FIG. 2, UE1 and UE2 can communicate directly over a PC5 interface. In sidelink communication, a UE that transmits data to another UE may be referred to as a TX UE, and a UE that receives data from another UE may be referred to as a RX UE, destination UE, or destination. For example, if UE1 transmits sidelink data to UE2, UE1 is the TX UE and UE2 is the RX UE.

[0024] A UE involved in sidelink communication first needs to select transmission resources for transmitting sidelink data to a peer UE (i.e., an RX UE). The transmission resources (which may also be referred to as resources for simplicity) occupy both time-domain and frequency-domain resources. The UE may transmit sidelink data during a transmission opportunity using the transmission resources. Specifically, the UE may be configured with a resource pool including multiple transmission resources that may serve as candidate resources. For example, a base station may configure a resource pool for the UE, and the UE may seek preferred and / or non-preferred transmission resources from neighboring UEs to create or update its transmission resource pool. The UE may also deploy a sensing mechanism to obtain resource utilization information from other neighboring UEs, and other resource discovery mechanisms may also be deployed by the UE. There are various mechanisms for supporting transmission resource selection in the sidelink, including the following: Transmission Mode 1

[0025] The serving base station specifies the transmission resources via a Downlink Control Indicator (DCI) message (e.g., DCI format 5) sent to the TX UE. This mode requires the TX UE to be under cellular coverage and may further require the TX UE to be in a connected state. Transmission Mode 2

[0026] The TX UE self-selects transmission resources according to predefined rules aimed at minimizing collision risk. This mode can be utilized when the UE is connected, idle, or out of coverage. Transmission Submode 2a

[0027] Each UE autonomously selects its transmission resources. Transmission submode 2b

[0028] A UE assists other UEs in performing transmission resource selection. The UE providing assistance may be an RX UE, which may inform a TX UE of its preferred or non-preferred resources. A UE assisting another UE may be referred to as UE-A, and an assisted UE may be referred to as UE-B. UE-B may request assistance information for transmission resource selection from UE-A through a UE-to-UE coordination process. Specifically, UE-B may send an UE-to-UE coordination request to UE-A when a certain condition is met, for example, when a periodic timer expires or when the assistance information is deemed stale. The assistance information may be classified into the following three types: Type-A: Transmission resources prioritized by UE A Type-B: Transmission resources not prioritized by UE A Type-C: Transmission resource where collision is detected by UE A

[0029] It should be understood that once UE-B receives Type-B or Type-C auxiliary information, UE-B may correspondingly derive non-Type-B or non-Type-C transmission resources, for example, from its configured resource pool.

[0030] In some embodiments, when selecting transmission resources, the UE may consider the size and priority of data to be transmitted using the sidelink. During a sidelink data transmission session, the UE may have multiple data packets that need to be transmitted in multiple transmission opportunities. The UE may pre-select transmission resources for each transmission. The transmission opportunities may be periodic, e.g., every two seconds. As an example, the UE may transmit data packet 1 in the first transmission opportunity and transmit data packet 2 in the second transmission opportunity, two seconds after the first transmission opportunity. In another example, the UE may pre-select ten transmission opportunities with a periodicity of three seconds. Depending on the availability of data to be transmitted, the UE may use all ten transmission opportunities or may skip some of the transmission opportunities if no data needs to be transmitted during those transmission opportunities.

[0031] In some embodiments, the UE may select transmission resources for a first sidelink data packet and then select transmission resources for subsequent data packets.

[0032] The UE may also select transmission resources for data retransmissions to be used if the initial data transmission fails.

[0033] In sidelink communication, a UE may also transmit control signals, which may be referred to as sidelink control information (SCI) messages, to peer UEs via a physical sidelink control channel (PSCCH). The SCI may be used to describe the dynamic transmission characteristics of the subsequent physical sidelink shared channel (PSSCH). Brief Description of the Embodiments

[0034] In the present disclosure, various embodiments are disclosed to solve various problems or to provide further improvements to sidelink communications. These embodiments cover various aspects of sidelink communications, such as: Sidelink transmission resource selection in DRX mode Sidelink transmission resource selection / reselection · UE cooperation for transmission resource selection Logical channel prioritization Auxiliary information reporting via shared transmission resources Embodiment 1: Resource Selection under DRX

[0035] Currently, for sidelink communication, there is no mechanism for the UE to negotiate a time window for sidelink data transmission. The UE may need to continuously monitor its data reception channel to aid its sidelink data transmission resource selection, which leads to increased power consumption.

[0036] In this embodiment, a discontinuous reception (DRX) mechanism is introduced into the sidelink communication. Figure 3 illustrates an exemplary DRX configuration. UEs receiving sidelink data (i.e., RX UEs) are configured with DRX. In each DRX cycle 310, the RX UE wakes up and is in an active state for an on duration 312. The RX UE then goes to sleep during the quiescent period of the DRX cycle 310 to save power. The RX UE may receive sidelink data only when it is active.

[0037] For a UE transmitting sidelink data (i.e., a TX UE), in some embodiments, as shown in FIG. 3, the TX UE may select a transmission resource that falls during the active time of the RX UE to ensure that the RX UE is able to receive the sidelink data.

[0038] In some embodiments, in addition to the DRX mechanism, the RX UE may further be configured with an inactivity timer (or inactivity timer). Once the RX UE receives sidelink data, the inactivity timer is started with a configurable timer duration, e.g., 10 seconds. Then, within the following 10 seconds, RX remains active. If no data is received within these 10 seconds, the RX UE may go back to sleep once the timer expires; if data is received, the RX UE resets (i.e., restarts) the inactivity timer in response to data reception and remains active. Referring to FIG. 4, at 420, the RX UE receives a sidelink data packet, which is transmitted by the TX UE using transmission resource 410. In response to receiving the sidelink data packet, the RX UE starts an inactivity timer. Thereafter, at 422, the RX UE receives another data packet transmitted by the TX UE using transmission resource 412. The RX UE resets the inactivity timer and remains active. The RX UE then receives another sidelink data packet corresponding to transmission resource 414. Since the inactivity timer has not expired, the RX UE is still active and able to receive data. Similarly, although not shown in Figure 4, the RX UE resets the timer again.

[0039] The inactivity timer described above is for example purposes only, and other methods for checking and determining the active time of a UE may also exist and are not limited to this disclosure.

[0040] Based on the above description, the TX UE may select a transmission resource taking into account an inactivity timer configured on the RX UE to ensure that the RX UE is active when sidelink data is transmitted using the selected transmission resource. In some embodiments, the TX UE may follow the steps below to select a transmission resource, with reference to Figure 4. Step 1

[0041] The TX UE selects a transmission resource for the first sidelink data packet, the transmission resource falling within the RX UE active time. For example, the TX UE selects transmission resource 410 for transmitting the first sidelink data packet. Step 2

[0042] The TX UE selects transmission resources for the subsequent sidelink data packet. This selection may last for a periodicity t1. The TX UE chooses the value of t1 such that t1 is less than or equal to the length of the inactivity timer of the RX UE. For example, the TX UE selects transmission resources 412, 414, and 416 to be used for the subsequent sidelink data packet transmission. The selection of these transmission resources ensures that the RX UE, by using the inactivity timer, is active when the sidelink data packet is transmitted.

[0043] In some other embodiments, the TX UE may include a set of transmission resources associated with the sidelink data transmission session in an SCI and transmit the SCI to the RX UE. For example, the TX UE may indicate to the RX UE that there are four transmission resources (e.g., 410, 412, 414, and 416) that the TX UE reserves or expects to use. The RX UE may adjust its active time in turn once it has served all expected transmission resources. For example, after the RX UE has served transmission resource 416, e.g., after the RX UE has received data carried in transmission resource 416, the RX UE may no longer need to reset its inactivity timer. Embodiment 2: Resource Selection

[0044] A TX UE may conduct sidelink communication with multiple RX UEs. For example, a TX UE may have one unicast link (for sidelink) with RX UE1 and another unicast link (for sidelink) with RX UE2. In one scenario, RX UE1 is awake in DRX mode, but RX UE2 is not awake in DRX mode. In this case, RX UE1 may periodically transition to sleep mode, while RX UE2 may not transition to sleep mode. Based on the current sidelink implementation, a TX UE may select a transmission resource as long as any one of the destination UEs (i.e., RX UEs) is active for that transmission resource. Therefore, there is a possibility that a TX UE may select a transmission resource that is suitable for RX UE2 but not for RX UE1 because RX UE1 may be in sleep mode for the selected transmission resource.

[0045] Various solutions are disclosed in this embodiment to cover transmission resource selection under the scenarios mentioned above. Solution 1

[0046] During transmission resource selection, the TX UE first finds and selects logical channels that have available data to be transmitted over the sidelink. For example, there are 10 logical channels, and the UE finds that 6 of these logical channels have available data.

[0047] Among the six selected logical channels, the TX UE further selects the logical channel with the highest priority. The TX UE selects sidelink transmission resources based on the selected logical channel. Solution 2

[0048] During transmission resource selection, the TX UE first finds and selects a logical channel with a number of available tokens greater than 0. For example, there are 10 logical channels, and the UE finds three of these logical channels with a number of tokens greater than 0.

[0049] The TX UE further selects the logical channel with the highest priority among the three selected logical channels. The TX UE selects sidelink transmission resources based on the selected logical channel. Solution 2a

[0050] During transmission resource selection, the TX UE first finds and selects the logical channel with the most tokens. The TX UE selects sidelink transmission resources based on the selected logical channel. Alternatively, the TX may rank the logical channels based on the tokens owned by each of the logical channels and select the top-ranked n logical channels, where n is a non-negative integer. Solution 3

[0051] The TX UE is configured with a sidelink transmission resource pool (which may also be referred to as resources for simplicity) that includes multiple transmission resources. The TX UE may rank these transmission resources based on the number of RX UEs for which the transmission resource is suitable. For example, if a transmission resource does not fall into a period in which the RX UE is active, the transmission resource is not suitable for that particular RX UE. The more RX UEs a transmission resource is suitable for, the higher the rank it is given. The TX UE may select the transmission resource with the highest rank. Option 3a

[0052] If the active time of one specific destination does not overlap with any other destination, the TX UE may separately select transmission resources within the active time of this specific destination, and the transmission resources may be dedicated to the specific destination. Option 4

[0053] In some embodiments, different RX UEs may be configured with different DRX configurations, e.g., different DRX cycles. The TX UE may divide these different DRX configurations into multiple sets. For example, a first set corresponds to a first DRX cycle range, and a second set corresponds to a second DRX cycle range. For each set of DRX configurations, the TX UE may configure a corresponding sidelink communication configuration. The sidelink communication configuration may include at least one of a data radio bearer (DRB) configuration or a logical channel configuration.

[0054] In some implementations, the TX UE may be configured such that one sidelink communication configuration applies to destinations for which DRX is disabled and another sidelink communication configuration applies to destinations for which DRX is enabled. Option 5

[0055] The TX UE may select or configure a set of transmission resources for each destination. Embodiment 3: Resource reselection

[0056] The TX UE may pre-select transmission resources for future sidelink data transmissions. For example, referring to FIG. 4, the TX UE may pre-select transmission resources 412, 414, and 416 when selecting transmission resource 410. Under certain conditions, the TX UE may later determine that the pre-selected transmission resources are no longer suitable for sidelink data transmission, e.g., if the RX UE is not active for the pre-selected transmission resources. In this case, the TX UE may trigger transmission resource reselection.

[0057] In another scenario, the TX UE may estimate or evaluate whether the RX UE is active, for example, by checking an inactivity timer or a retransmission timer. However, under certain conditions, the estimation or evaluation based on these timers may be inaccurate. For example, if sidelink data is not transmitted in a transmission opportunity, see FIG. 4 , if no data is transmitted on transmission resource 414, the inactivity timer of the RX UE may not be reset, which may cause the RX UE to transition to an inactive state for transmission resource 416, and thus, transmission resource 416 may no longer be suitable for the RX UE. In another example, the SCI carrying control information may be blocked or not transmitted to the RX UE due to intra-UE prioritization, causing the estimation based on the retransmission timer to become infeasible. In this scenario, the TX UE has two options: Option 1 The TX UE may trigger a transmission resource reselection. Option 2 The TX UE may remove the unsuitable resources and select another resource to replace the unavailable resource with a newly selected resource in the resource pool. Embodiment 4: Destination Selection

[0058] In sidelink communication, the TX UE performs a logical channel prioritization (LCP) procedure to meet the priority requirements of each logical channel. When a destination (or a RX UE) is awake in DRX mode, the TX UE may determine whether the destination is active. If the destination is not active during the LCP procedure, this particular destination is skipped and logical channels associated with the inactive destination are not served. In other words, the TX UE may consider a logical channel only if its associated destination is active during the LCP procedure. Embodiment 5: TX UE initiates inter-UE cooperation

[0059] As described above, in sidelink communication, an assisting UE (i.e., UE-A) may assist another UE to select transmission resources. UE-A may send a set of resources to the assisted UE (i.e., UE-B). The TX UE may initiate a request to a peer UE for transmission resource information, i.e., the TX UE may initiate an inter-UE coordination request.

[0060] If the TX UE makes inter-UE coordination requests too frequently, it may cause excessive traffic and other overhead between the UEs, and if previously obtained resource information is still valid, coordination is unnecessary. On the other hand, if the TX UE waits too long to initiate a coordination request, the previously obtained resource information may become stale, which may slow down the resource selection process and lead to delays in sidelink data transmission.

[0061] In this embodiment, various conditions are disclosed such that the TX UE initiates an inter-UE coordination request when one or more of these conditions are met. These conditions include: When the sidelink data to be transmitted has a priority or reliability requirement higher than the configured threshold. ·When the channel busy rate of the TX UE is higher than the pre-configured threshold. · The number of intermittent transmissions to UE-A is greater than a preconfigured threshold. · The number of Hybrid Automatic Repeat Request Negative Acknowledgments (HARQ NACKs) received from UE-A is greater than a pre-configured threshold. · Peer UEs must support inter-UE cooperation. Sidelink data for a logical channel associated with a destination (e.g., RX UE) becomes available to the MAC entity of the TX UE, and this sidelink data either belongs to a logical channel with higher priority than the priority of a logical channel containing available sidelink data belonging to any LCG (LC Group) belonging to the same destination (same RX UE), or none of the logical channels belonging to a logical channel group (LCG) belonging to the same destination contains any available sidelink data. When a periodic timer for UE-to-UE coordination expires. For example, the TX UE maintains a timer, and once the timer expires, the TX UE transmits a UE-to-UE coordination request and starts or restarts the timer during that time. The TX UE does not receive a response to the UE-to-UE coordination request. For example, the TX UE may start another timer once the UE-to-UE coordination request is transmitted to UE-A. Once the timer expires, the TX UE retransmits the UE-to-UE coordination request, and the TX UE stops the timer once the TX UE receives assistance information from UE-A. In another embodiment, the UE is configured with a retransmission number threshold, and if the number of requested retransmissions reaches the threshold, the TX UE considers UE-A to be unavailable. In this case, the TX UE may trigger a UE-A reselection procedure. The set of resources provided by UE-A is stale. For example, the TX UE (acting as UE-B) has a keep-fresh timer, which is started or reset once the TX UE receives a new set of resources from UE-A. When the timer expires, the TX UE considers the set of resources to be stale. When a resource in the set of resources provided by UE-A is consumed. For example, the TX UE may maintain a counter with a predefined initial value, and the counter is decremented each time a resource from the resource set is selected. Once the counter reaches 0 (or another predefined value), a UE-to-UE coordination request is triggered. In some embodiments, once the counter reaches 0 (or another predefined value), the TX UE may randomly select a value from the interval [0,1] with equal probability. If the selected value is above a configured threshold, the TX UE may trigger a UE-to-UE coordination request. When the UE's sidelink transmission resource pool or the UE's sensing parameters are reconfigured. If there are no resources selected from the transmission resource pool or there are no suitable resources for sidelink transmission in the resource pool. · If the TX UE does not refer to or select any resource indicated by UE-A for selecting a transmission resource during the last (i.e., previous) N seconds (N is an integer). · If the number of consecutive unused transmission opportunities on the resources indicated by UE-A is equal to a predefined value (e.g., sl-ReselectAfter). ·If the transmission resources in the set of transmission resources provided by UE-A cannot accommodate the maximum allowed modulation and coding scheme configured for the TX UE. If the transmission resources in the set of transmission resources provided by UE-A are not able to meet the latency requirements of the sidelink data transmission. If the TX UE acting as UE-B determines that the resources sensed by it do not overlap with the Type-A resources provided by UE-A, or if the overlap rate is below a configured threshold. For example, if 5 out of 10 resources sensed by the TX UE overlap with Type-A resources, the overlap rate is 50%. ·When a TX UE acting as UE-B determines that all resources sensed by itself overlap with Type-B or Type-C resources provided by UE-A, or when the overlap rate between the self-sensed resources and Type-B or Type-C resources is greater than a configured threshold.

[0062] In some embodiments, the TX UE acting as UE-B may consider the set of resources provided by UE-A to be stale if any one of the above conditions is met.

[0063] In some embodiments, considering that there is a time gap between transmitting the UE-to-UE coordination request and receiving a response from UE-A, UE-B may still use the resources provided by UE-A during the time gap. Specifically, after UE-B sends the UE-to-UE coordination request, UE-B may start a timer, and if the timer is running, UE-B may consider the set of resources provided by UE-A to be available. UE-B stops the timer when a response including the new set of resources is received from UE-A.

[0064] Sensing parameters that may be used by UE-A may include: ·SL_RESOURCE_RESELECTION_COUNTER value Number of sub-channels Resource Reservation Interval Service priority Preemption Priority -Indication of whether preemption is enabled or disabled Packet Delay Budget HARQ feedback configuration (indicates whether UE-A needs a sensing resource pool with PSFCH resources) A sensing window defined by a timer interval Candidate resource selection window defined by timer interval A bitmap of slots in the candidate resource selection window that UE-A needs to sense (for partial sensing) Allowed values ​​for signaling resource reservation period RSRP Threshold Reference signal, i.e., PSSCH-RSRP or PSCCH-RSRP The percentage of remaining candidate single-slot resources in the candidate resource set RSRP threshold increment step Resource pool related configuration

[0065] It should be understood that in the present disclosure, thresholds, parameters, or counters may be configured based on practical needs by those skilled in the art, which may be configured per priority, per destination, per Quality of Service (QoS) requirement, or per service type. The configuration may be performed by the network via broadcast messages (e.g., Master Information Block (MIB), System Information (SI)), Radio Resource Control (RRC) messages, and the like.

[0066] In some embodiments, if a radio link failure (RLF) is triggered on UE-A, UE-B may consider the set of resources provided by UE-A to be out of date.

[0067] In some embodiments, if the connection between UE-A and UE-B is released or becomes unavailable, UE-B may consider the set of resources provided by UE-A to be stale.

[0068] In some embodiments, UE-B may further include a trigger condition in the UE-to-UE cooperation request to UE-A, so that UE-A may know the reason for sending this UE-to-UE cooperation request. Correspondingly, UE-A may make adjustments when collecting and reporting assistance information to UE-B. For example, UE-A may adjust a Reference Signal Received Power (RSRP) threshold, a Reference Signal Received Quality (RSRQ) threshold, or the like when collecting transmission resource information to be sent to UE-B.

[0069] In some embodiments, if one of the following conditions is met: UE-B determines that the resources sensed by it do not overlap with the Type-A resources provided by UE-A, or the overlap rate is below a configured threshold. UE-B determines that the resources sensed by it all overlap with Type-B or Type-C resources provided by UE-A, or the overlap rate is higher than the configured threshold.

[0070] UE-B may indicate to its physical layer to resensing resources. UE-B may also stop at least one of the timers associated with the UE-to-UE coordination request for this particular UE-A. Embodiment 6: Resource Selection and LCP for Mode 2b

[0071] UE-B may select transmission resources by taking into account the set of resources provided by UE-A. If the set of resources is out of date, UE-B may not consider the set of resources.

[0072] In some embodiments, if Type-A resources provided by UE-A are present, UE-B may prioritize Type-A resources during resource selection when selecting resources for UE-A. If Type-B or Type-C resources provided by UE-A are present, UE-B may prioritize non-Type-B or non-Type-C resources during resource selection.

[0073] In some embodiments, if Type-A resources provided by UE-A exist and if the provided resources are stale, UE-B may prioritize Type-A resources during resource selection. If Type-B or Type-C resources provided by UE-A exist and if the resources are not stale, UE-B may prioritize non-Type-B or non-Type-C resources during resource selection.

[0074] In some embodiments, UE-B may have unicast links with multiple RX UEs. Of these RX UEs, one RX UE is capable of providing auxiliary information (i.e., acting as UE-A), while the others are not. In other words, when communicating with UE-B, one RX UE acting as UE-A indicates to UE-B using Type-A resources that the RX UE prefers to use. The other RX UEs do not have this preference or limitation. Therefore, UE-B may select transmission resources from the entire resource pool, and it is highly likely that UE-B will not select the Type-A resources provided and preferred by the RX UE acting as UE-A. To solve this problem, UE-B has the following options: When selecting transmission resources, UE-B prioritizes (or considers higher priority to) Type-A, non-Type-B, or non-Type-C resources. If there is assistance information provided by multiple UE-As, UE-B prioritizes the resource that uses the most overlapping of these pieces of assistance information. Furthermore, if UE-B performs resource sensing and has self-sensed resources, UE-B prioritizes the resource that uses the most overlapping of these pieces of assistance information and self-sensed resources. If the Type-A, non-Type-B, or non-Type-C resources provided by a specific UE-A do not overlap with any other set of resources provided by other UE-As or with resources sensed by the UE-B itself, the UE-B may select transmission resources for the specific UE-A separately. UE-B may select a set of resources for each UE-A based on the aiding information provided by each UE-A.

[0075] In some embodiments, if UE-A provides only limited Type-A resources to UE-B, e.g., if the number of Type-A resources is below a threshold, the network may increase the priority of this UE-A so that sidelink data transmitted to UE-A may get more opportunities to be transmitted.

[0076] In some embodiments, a UE may be configured with multiple sets of sidelink configurations. The sidelink configurations may include a DRB configuration and an LCH configuration. One set may be used for destination UEs for which inter-UE cooperation capability is enabled, and another set may be used for destination UEs for which inter-UE cooperation capability is not enabled or which do not support inter-UE cooperation.

[0077] In some embodiments, multiple types of inter-UE coordination exist corresponding to the type of assistance information provided by UE-A, whether it be Type-A, Type-B, or Type-C resource information. A UE may be configured with multiple sets of sidelink configurations, each corresponding to a type of inter-UE coordination.

[0078] In some embodiments, the UE may be configured with multiple sets of sidelink configurations based on a ratio or ratio range between the number of Type-A resources provided by UE-A and the total number of resources in the transmission resource pool. For example, if there are 100 transmission resources in the transmission resource pool and 20 of these transmission resources overlap with the Type-A transmission resources provided by UE-A, the ratio is 20%. The UE may select a sidelink configuration for destination UE-A based on the ratio.

[0079] When the UE is performing an LCP procedure or when the UE is performing Mode 2b sidelink resource selection, the TX UE may select a destination UE (RX UE) under one of these conditions. The selected sidelink transmission resource is within the set of preferred resources (Type-A) provided by UE-A. The selected sidelink transmission resource is not within the set of non-prioritized resources (type B) provided by UE-A. The selected sidelink transmission resource is not within the set of collision resources (Type-C) provided by UE-A.

[0080] In some embodiments, it is a prerequisite for the above condition that the selected resource is not stale or that the resource selection is based on a resource that is not stale.

[0081] In some embodiments, UE-A may be able to provide only the supplemental resource selection information that applies to itself. In this case, UE-B only considers the provided supplemental resource selection information when selecting resources for this particular UE-A. In some other embodiments, UE-A may provide the supplemental resource selection information that applies to itself and a set of other UEs, and UE-B then considers the provided supplemental resource selection information when selecting resources for this particular UE-A and the set of other UEs. Embodiment 7: UE-A sends resource report

[0082] UE-A may report a set of resources by using a Medium Access Control Element (MAC CE). When performing the LCP procedure, if there are remaining bits (or capacity) in the transmission resources after data multiplexing, instead of ignoring or wasting the remaining capacity, UE-A may use the remaining bits to report a set of resources if the remaining capacity is sufficient to hold the MAC CE for reporting.

[0083] Specifically, UE-A may use the remaining capacity after data multiplexing if any of the following conditions are met: If the size of this MAC CE is fixed, the remaining bits after data multiplexing are greater than the size of the MAC CE plus its subheader, or If the size of this MAC CE is not fixed, the size of the MAC CE depends on the number of resources in the MAC CE, and the remaining bits after data multiplexing are greater than the minimum size of the MAC CE plus its subheader.

[0084] The descriptions and examples in this disclosure are provided from the perspective of a network (e.g., a base station) or a UE. It should be understood that the network and the UE operate in a coordinated manner. The principles applied on the network side also apply to the UE side. For example, when the network transmits a WUB to the UE, the basic principles for transmission also apply to the UE's reception of the WUB.

[0085] The above description and accompanying drawings provide specific exemplary embodiments and implementations. However, the described subject matter may be embodied in a variety of different forms, and thus, it is intended that the covered or claimed subject matter be construed as not limited to any exemplary embodiments set forth herein. A reasonably broad scope for the claimed or covered subject matter is intended. Among other things, for example, the subject matter may be embodied as a method, device, component, system, or non-transitory computer-readable medium for storing computer code. Thus, embodiments may take the form of, for example, hardware, software, firmware, a storage medium, or any combination thereof. For example, the method embodiments described above may be implemented by a component, device, or system including a memory and a processor by executing computer code stored in the memory.

[0086] Throughout this specification and the claims, terms may have subtle meanings that are suggested or implied in context beyond those explicitly stated. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to a different embodiment. For example, it is intended that claimed subject matter include, in whole or in part, any combination of the example embodiments.

[0087] Generally, terminology can be understood, at least in part, from its use in context. For example, terms such as "and," "or," or "and / or," as used herein, can include a variety of meanings that may depend, at least in part, on the context in which such terms are used. Typically, when "or" is used to relate a list such as A, B, or C, it is intended to refer to A, B, and C, used herein in an inclusive sense, and to A, B, or C, used herein in an exclusive sense. Additionally, the term "one or more," as used herein, can be used to describe any feature, structure, or characteristic in a singular sense, or to describe a combination of features, structures, or characteristics in a plural sense, at least in part, depending on the context. Similarly, terms such as "a," "an," or "the" can be understood to convey the use of the singular or the use of the plural, at least in part, depending on the context. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but instead, can allow for the existence of additional factors not necessarily explicitly described, again, at least in part, depending on the context.

[0088] References to features, advantages, or similar terms throughout this specification do not imply that all of the features and advantages that may be realized using the present solution should or are included in any single implementation thereof. Rather, terms referring to features and advantages are understood to mean that the specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present solution. Thus, discussions of features and advantages and similar terms throughout this specification may, but do not necessarily, refer to the same embodiment.

[0089] Furthermore, the described features, advantages, and characteristics of the solution may be combined in any suitable manner in one or more embodiments. Those skilled in the art will recognize, in light of the description herein, that the solution may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the solution.

Claims

1. 1. A method for sidelink communication in a wireless communication network, performed by a first UE, comprising: initiating a sidelink data transmission session with a second UE operating in a discontinuous reception (DRX) mode; selecting, during a first active time of the second UE, a first transmission resource for transmitting a first data packet of the sidelink data transmission session to the second UE; and determining, in response to the first transmission resource being no longer within an active time of the second UE, that the first transmission resource is no longer suitable for sidelink data transmission; and updating the first transmission resources with second transmission resources that are suitable for sidelink data transmission, wherein the updating Triggering a transmission resource reselection procedure, or selecting the second transmission resource from a transmission resource pool maintained by the first UE to replace the first transmission resource; and A method comprising:

2. 2. The method of claim 1, further comprising selecting the second transmission resource for transmitting subsequent data packets of the sidelink data transmission session to the second UE during a second active time of the second UE.

3. 2. The method of claim 1, further comprising selecting transmission resources for subsequent sidelink data packets, wherein a time interval between selections of the transmission resources for the subsequent sidelink data packets is equal to or less than a duration of an inactivity timer managed by the second UE in response to receiving a subsequent data packet of the sidelink data transmission session.

4. The method of claim 1 , wherein the first UE is awake in a DRX mode.

5. configuring a first logical channel configuration to support a first sidelink data transmission to a first destination UE operating in DRX mode; and configuring a second logical channel configuration to support a second sidelink data transmission to a second destination UE that is not activating in the DRX mode; and The method of claim 4 further comprising:

6. Selecting the first transmission resource comprises: selecting, during the first active time of the second UE, the first transmission resource for transmitting the first data packet of the sidelink data transmission session to the second UE in accordance with a DRX configuration of the second UE. The method of claim 1 , comprising:

7. 1. A method for sidelink communication in a wireless communication network, the method being performed by a first UE configured with pre-selected transmission resources in a transmission resource pool for supporting sidelink data transmission to a second UE, the method comprising: determining, in response to the preselected transmission resource being no longer within an active time of the second UE, that the preselected transmission resource is no longer suitable for sidelink data transmission; and updating the pre-selected transmission resources with second transmission resources that are suitable for sidelink data transmission, wherein the updating Triggering a transmission resource reselection procedure, or selecting the second transmission resource from a transmission resource pool maintained by the first UE to replace the pre-selected transmission resource; and A method comprising:

8. configuring a first logical channel configuration to support sidelink data transmission to a first set of destination UEs operating in DRX mode, wherein a DRX cycle of each of the first set of destination UEs is within a first range; and configuring a second logical channel configuration to support sidelink data transmission to a second set of destination UEs operating in DRX mode, wherein the DRX cycle of each of the second set of destination UEs is within a second range; and The method of claim 1 further comprising:

9. and transmitting a sidelink control information (SCI) message to the second UE before initiating the sidelink data transmission session, the SCI message including a set of transmission resources to be reserved by the second UE for supporting the sidelink data transmission session.

2. The method of claim 1, wherein selecting the first transmission resource during the first active time of the second UE comprises selecting the first transmission resource from the set of transmission resources.

10. the sidelink data transmission session is associated with a set of logical channels; The method of claim 1 , further comprising determining a logical channel from the set of logical channels based on a predefined condition.

11. The predefined condition is: the logical channel having the highest priority among all logical channels in the set of logical channels having sidelink data available for transmission, or the logical channel having the highest priority among all logical channels in the set of logical channels having a number of tokens greater than 0 The method of claim 10, comprising one of:

12. 1. A first device for sidelink communication in a wireless communication network, the first device comprising: a memory for storing computer instructions; and a processor in communication with the memory, the processor executing the computer instructions causing the processor to: initiating a sidelink data transmission session with a second device operating in a discontinuous reception (DRX) mode; selecting, during a first active time of the second device, a first transmission resource for transmitting a first data packet of the sidelink data transmission session to the second device; and determining, in response to the first transmission resource being no longer within an active time of the second device, that the first transmission resource is no longer suitable for sidelink data transmission; and updating the first transmission resources with second transmission resources that are suitable for sidelink data transmission, wherein the updating Triggering a transmission resource reselection procedure, or selecting the second transmission resource from a transmission resource pool maintained by the first device to replace the first transmission resource; and a first device configured to cause the first device to perform

13. When the processor executes the computer instructions, the processor: selecting the second transmission resource for transmitting subsequent data packets of the sidelink data transmission session to the second device during a second active time of the second device. The first device of claim 12 , further configured to cause the first device to:

14. When the processor executes the computer instructions, the processor: selecting transmission resources for subsequent sidelink data packets, wherein a time interval between selections of the transmission resources for the subsequent sidelink data packets is equal to or less than a duration of an inactivity timer managed by the second device, the inactivity timer being reset by the second device in response to receiving subsequent data packets of the sidelink data transmission session. The first device of claim 12 , further configured to cause the first device to:

15. The first device of claim 12 , wherein the first device is powered on in a DRX mode.

16. When the processor executes the computer instructions, the processor: configuring a first logical channel configuration to support a first sidelink data transmission to a first destination device operating in DRX mode; and configuring a second logical channel configuration to support a second sidelink data transmission to a second destination device that is not activating in the DRX mode; and The first device of claim 15 , further configured to cause the first device to:

17. A device comprising one or more processors, the one or more processors configured to implement the method of claim 7.

18. 10. A computer-readable storage medium having computer code stored thereon that, when executed by one or more processors, causes the one or more processors to implement the method of claim 1.

19. 10. A computer-readable storage medium having computer code stored thereon that, when executed by one or more processors, causes the one or more processors to implement the method of claim 7.

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