METHOD AND USER EQUIPMENT FOR SIDELINK PACKET SWITCHING OPERATION - Patent application

Abstract

To provide user equipment (UE) that performs sidelink (SL) communication capable of connected mode DRX (Discontinuous Reception).SOLUTION: In a wireless communication system, a first UE receives an SL-DRX configuration indicating an SL-DRX capability, and determines whether to monitor at least one of first sidelink control information (SCI) on a physical sidelink control channel (PSCCH), an SL packet on a physical sidelink shared channel (PSSCH), and a second SCI on the PSSCH according to switching between an SL-DRX active time and an SL-DRX off period, and determines both the SCI is from at least one second UE and the SL-DRX active time and the SL-DRX off period by the SL-DRX capability.SELECTED DRAWING: Figure 6

Description

Detailed Description of the Invention

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure is a national stage application filed under 35 U.S.C. 371 of International Patent Application PCT / CN / 2021 / 073121, filed January 21, 2020, which claims the benefit of and priority to U.S. Patent Application Serial No. 62 / 964,012, filed January 21, 2020, entitled "Sidelink Discontinuous Reception (SL-DRX) Mechanisms," the contents of which are incorporated herein by reference in their entirety for all purposes.

[0002] [Field] The present disclosure relates generally to wireless communications, and more particularly to methods and user equipment for SideLink (SL) packet-switched operations.

[0003] 〔background〕 With the significant increase in the number of connected devices and the rapid increase in user / network traffic volume, various efforts have been made to improve different aspects of wireless communications for next generation wireless communication systems, such as fifth generation (5G) New Radio (NR), by improving data speed, latency, reliability, and mobility.

[0004] The 5G NR system is designed to provide flexibility and configurability to optimize network services and network types for various use cases, such as enhanced Mobile Broadband (eMBB), massive Machine-Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC).

[0005] However, as wireless access demands continue to increase, further improvements in sidelink (SL) packet switched operation are needed.

[0006] The present disclosure is directed to a method and user equipment (UE) for sidelink (SL) packet-switched operation.

[0007] According to a first aspect of the present disclosure, there is provided a method performed by a first user equipment (UE) for sidelink (SL) packet switching operation, the method including: receiving at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the first UE; when SL-DRX operation is performed based on the at least one SL-DRX configuration, performing partial detection based on at least one of the plurality of SL resource pool configurations, wherein each of the at least one SL resource pool configured by the at least one SL resource pool configuration includes one or more time slots; performing SL-Channel Busy Ratio (SL-CBR) measurements associated with each of the at least one SL resource pool in the one or more time slots for which partial detection is performed; and receiving an indicator, wherein the first UE determines, based on the indicator, whether to perform the partial detection on a first SL resource pool configured by the first SL resource pool configuration during at least one SL-DRX off period.

[0008] According to a second aspect of the present disclosure, there is provided a user equipment (UE) in a wireless communication system comprising a base station (BS) for sidelink (SL) packet switched operation. a UE comprising: one or more non-transitory computer-readable media having computer-executable instructions; and at least one processor coupled to the one or more non-transitory computer-readable media, the at least one processor configured to execute the computer-executable instructions to cause the UE to perform the following steps: receive at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the UE; when an SL-DRX operation is performed based on the at least one SL-DRX configuration, perform partial detection based on at least one of the plurality of SL resource pool configurations, wherein each of the at least one SL resource pool configured by at least one of the plurality of SL resource pool configurations includes one or more time slots; perform SL-Channel Busy Ratio (SL-CBR) measurements associated with each of the at least one SL resource pool in the one or more time slots for which the partial detection is performed; and receive an indicator; and determine, based on the indicator, whether the UE will perform the partial detection on a first SL resource pool configured by a first SL resource pool configuration during at least one SL-DRX off period.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present disclosure are best understood from the following when read in conjunction with the accompanying figures, in which: Various features are not drawn to scale, and dimensions of various features may be arbitrarily increased or decreased for clarity of discussion.

[0010] FIG. 1 is a diagram illustrating SL operations for UEs to exchange information according to an exemplary embodiment of the present disclosure.

[0011] FIG. 2 is a diagram illustrating a V2X platoon scenario in accordance with an example implementation of the present disclosure.

[0012] FIG. 3 is a diagram illustrating a PC5-RRC connection between a pair of UEs in accordance with an example implementation of the present disclosure.

[0013] FIG. 4 is a diagram illustrating SL-DRX configuration according to an exemplary implementation of the present disclosure.

[0014] 5(a), 5(b), and 5(c) are diagrams illustrating different sidelink (SL) sensing windows according to different example implementations of the present disclosure.

[0015] FIG. 6 is a diagram illustrating an SL packet exchange procedure performed by a first UE in accordance with an example implementation of the present disclosure.

[0016] FIG. 7 is a block diagram of a node for wireless communication in accordance with an example implementation of the present disclosure.

[0017] [Description] The following contains specific information relating to exemplary embodiments of the present disclosure. The drawings and the accompanying detailed disclosure are directed to exemplary embodiments only. However, the present disclosure is not limited to these exemplary embodiments only. Other variations and embodiments of the present disclosure will occur to those skilled in the art. Unless otherwise specified, like or corresponding elements between the drawings may be indicated by like or corresponding reference numerals. Furthermore, the drawings and illustrations in this disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

[0018] The following contains specific information relating to examples of the present disclosure. The drawings and the accompanying detailed disclosure are directed to exemplary embodiments only. However, the present disclosure is not limited to these exemplary embodiments only. Other variations and embodiments of the present disclosure will occur to those skilled in the art. Unless otherwise specified, like or corresponding elements between the drawings may be indicated by like or corresponding reference numerals. Furthermore, the drawings and illustrations of the present disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

[0019] For consistency and ease of understanding, like features are identified by numerals in the exemplary figures (although in some instances not shown), however, features in different embodiments may differ in other respects and therefore are not intended to be narrowly limited to those illustrated in the figures.

[0020] References to "one implementation," "implementation," "exemplary implementation," "various implementations," "several implementations," "implementations of the present disclosure," etc. may indicate that an implementation of the present disclosure may include a particular feature, structure, or characteristic, but that all possible implementations of the present disclosure do not necessarily include that particular feature, structure, or characteristic. Furthermore, repeated use of the phrases "in one implementation," "in an exemplary implementation," or "an implementation" does not necessarily refer to the same implementation, although possible. Furthermore, any use of a phrase such as "implementation" in connection with "the present disclosure" should be understood to in no way imply that all implementations of the present disclosure must include a particular feature, structure, or characteristic, but instead to mean that "at least some implementations of the present disclosure" include the stated particular feature, structure, or characteristic. The term "coupled" is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to a physical connection. The term "comprising," when used, means "including, but not necessarily limited to," and it particularly indicates an open-ended inclusion or membership in so-disclosed combinations, groups, series, and the like.

[0021] The term "and / or" used herein is only a relational relationship for describing related objects and represents that three relationships may exist, for example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " used herein generally represents that the former and latter related objects are in an "or" relationship.

[0022] For purposes of explanation and not limitation, specific details of functional entities, techniques, protocols, standards, etc. are set forth to provide an understanding of the disclosed technology. In other instances, detailed descriptions of well-known methods, techniques, systems, and architectures are omitted so as not to obscure the disclosure with unnecessary detail.

[0023] Those skilled in the art will readily appreciate that any network function(s) or algorithm(s) in the present disclosure may be implemented by hardware, software, or a combination of software and hardware. The disclosed functions may correspond to modules, which may be software, hardware, firmware, or any combination thereof. Software implementations may comprise computer-executable instructions stored on a computer-readable medium, such as a memory or other type of storage device. For example, one or more microprocessors or general-purpose computers with communications processing capabilities may be programmed with corresponding executable instructions to execute the disclosed network function(s) or algorithm(s). The microprocessor or general-purpose computer may be formed using an application-specific integrated circuit (ASIC), a programmable logic array, and / or one or more digital signal processors (DSPs). While some implementations in the present disclosure are directed to software installed and executed on computer hardware, alternative embodiments implemented as firmware, hardware, or a combination of hardware and software are well within the scope of the present disclosure.

[0024] The computer readable medium may include, but is not limited to, random access memory (RAM), read only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM), magnetic cassette, magnetic tape, magnetic disk storage, or any other equivalent medium capable of storing computer readable instructions.

[0025] A wireless communication network architecture (e.g., a Long Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, or an LTE-Advanced Pro system) may typically include at least one base station (BS), at least one UE, and one or more optional network elements that provide connectivity to the network. The UE may communicate with a network (e.g., a core network (CN), an evolved packet core (EPC) network, an evolved universal terrestrial radio access network (E-UTRAN), a next-generation core (NGC), a 5G core (5GC), or the Internet) via a radio access network (RAN) established by the BS.

[0026] In this application, the term UE includes, but is not limited to, a mobile station, a portable terminal or device, and a user communication wireless terminal. For example, the UE may be a portable wireless device, including, but not limited to, a mobile phone, a tablet, a wearable device, a sensor, a vehicle, or a personal digital assistant (PDA) with wireless communication capabilities. The UE is configured to transmit and receive signals over the air interface to one or more cells in a wireless access network.

[0027] The BS is a Node B (NB) in the Universal Mobile Telecommunication System (UMTS), an evolved Node B (eNB) in LTE or LTE-A, a Radio Network Controller (RNC) in UMTS, a Base Station Controller (BSC) in the Global System for Mobile communications (GSM) / GSM Enhanced Data rates for GSM Evolution (EDGE) RAN (GERAN), a next-generation eNB (ng-eNB) in the evolved universal terrestrial radio access (E-UTRA) BS related to 5GC, and a next-generation Node B (gNB) in the 5G-RAN (or 5G access network (5G-AN)). B), and any other device capable of controlling wireless communication and managing radio resources within a cell. The BS may be connected to provide service to one or more UEs via a wireless interface to the NW.

[0028] The BS may be configured to provide communication services in accordance with at least one of the following Radio Access Technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), GSM (often referred to as 2G), GERAN, General Packet Radio Service (GPRS), UMTS based on basic Wideband-Code Division Multiple Access (W-CDMA) (often referred to as 3G), High-Speed ​​Packet Access (HSPA), LTE, LTE-A, enhanced LTE (eLTE), NR (often referred to as 5G), and LTE-A Pro. However, the scope of this disclosure should not be limited to these protocols mentioned above.

[0029] A BS may be operable to provide wireless coverage to a particular geographic area using multiple cells included in the RAN. The BS may support cell operation. Each cell may be operable to serve at least one UE within its wireless coverage. More specifically, each cell (often referred to as a serving cell) may serve one or more UEs within its wireless coverage. For example, each cell schedules downlink (DL) resources and optional UL resources to at least one UE within its wireless coverage for DL ​​packet transmissions and optional UL packet transmissions. A BS may communicate with one or more UEs in a wireless communication system via multiple cells. A cell may allocate SL resources supporting proximity services (ProSe). Each cell may have a coverage area that overlaps with other cells. In the case of Multi-RAT Dual Connectivity (MR-DC), the primary cell of a Master Cell Group (MCG) or Secondary Cell Group (SCG) may be called a Special Cell (SpCell). A Primary Cell (PCell) may refer to an SpCell of an MCG. A Primary SCG Cell (PSCell) may refer to an SpCell of an SCG. An MCG may refer to a group of serving cells associated with a Master Node (MN), consisting of an SpCell and optionally one or more Secondary Cells (SCells). An SCG may refer to a group of serving cells associated with a Secondary Node (SN), consisting of an SpCell and optionally one or more SCells.Also, note that in some implementations, the UE may not have a (LTE / NR) radio resource control (RRC) connection with the associated serving cell of the associated service (in other words, the UE may not have a UE-specific RRC signaling exchange with the serving cell). Instead, the UE may only monitor DL ​​synchronization signals (e.g., DL synchronization burst sets) and / or broadcast system information (SI) associated with the associated service from such serving cell. Furthermore, the UE may have one or more serving cells on one or more target SL frequency carriers for the associated service. In some additional implementations, the UE may consider a RAN that configures one or more serving cells as a serving RAN.

[0030] As discussed above, the frame structure for NR is to support flexible configurations to accommodate various next-generation (e.g., 5G) communication requirements such as eMBB, mMTC, and URLLC, while meeting the requirements of high reliability, high data rates, and low latency. rd The Orthogonal Frequency-Division Multiplexing (OFDM) technology agreed upon in the NR Generation Partnership Project may serve as the standard for NR waveforms. Scalable OFDM numerology, such as adaptive subcarrier spacing, channel bandwidth, and cyclic prefix (CP), may be used. Furthermore, two coding methods are considered for NR: (1) low-density parity-check (LDPC) codes and (2) polar codes. The application of the coding scheme may be configured based on channel conditions and / or service applications.

[0031] Furthermore, it is also considered that the transmission time interval of a single NR frame should include at least DL transmission data, a guard period, and UL transmission data, and that in each portion of the DL transmission data, the guard period, and the UL transmission data, for example, should also be configurable based on the NR network dynamics. In addition, SL resources may be provided through the NR frame to support ProSe services.

[0032] (General description of DRX operation) In some implementations, a UE may be configured with a DRX function that controls the UE's physical downlink control channel (PDCCH) monitoring activity. When DRX is configured in RRC_CONNECTED, the UE may not need to continuously monitor one or more PDCCHs. In some implementations, DRX may be characterized by the following: on-duration: This may be the period that the UE waits to receive the PDCCH after waking up. If the UE successfully decodes the PDCCH, the UE can stay awake and (re)start the inactivity-timer; · inactivity-timer: This may be the period the UE waits to successfully decode the PDCCH from the time of the last successful decoding of the PDCCH, and if it fails, it can put the UE back to sleep. The UE can restart the inactivity timer after one successful decoding of the PDCCH only on the first transmission (i.e., not on a retransmission); · Retransmission timer: This may be the period until a retransmission is expected (e.g., Hybrid Automatic Repeat Request, HARQ); · cycle: This allows specifying a periodic repetition of on periods followed by possible inactive periods; Active time: This may be the total time during which the UE monitors the PDCCH(s). This may include the "on period" of the DRX cycle, the time during which the UE is in continuous reception while the inactivity timer has not expired, and the time during which the UE is in continuous reception while waiting for a retransmission opportunity.

[0033] In some implementations, more detailed UE behavior may be introduced below: The Medium Access Control (MAC) entity, via the RRC layer / entity, implements the DRX function that controls the UE's PDCCH monitoring activity using the MAC entity's Cell-Radio Network Temporary Identifier (C-RNTI), Configured Scheduling-Radio Network Temporary Identifier (CS-RNTI), Interrupted-Radio Network Temporary Identifier (INT-RNTI), Slot Format Indication-Radio Network Temporary Identifier (SFI-RNTI), Semi-Persistent Channel State Information-Radio Network Temporary Identifier (SP-CSI-RNTI), Transmit Power Control-Physical Uplink Control Channel-Radio Network Temporary Identifier (TPC-PUCCH-RNTI), Transmit Power Control-Physical Uplink Shared Channel-Radio Network Temporary Identifier (TPC-PUSCH-RNTI), Modulation and Coding Scheme Cell-RNTI (MCS-C-RNTI), and Transmit Power Control-Physical Uplink Control Channel (SPC-CNTTI). These include Random Access-RNTI (RA-RNTI), Paging-RNTI (P-RNTI), System Information-RNTI (SI-RNTI), Sidelink-RNTI (sl-RNTI), Sidelink Configuration Scheduling-RNTI (sl-CS-RNTI), and Transmit Power Control-Phonetic Reference Symbol-Radio Network Temporary Identifier (TPC-SRS-RNTI). When using DRX operation, the MAC entity may also monitor one or more PDCCHs in accordance with the requirements of the 3GPP Technical Specifications (TS). In RRC_CONNECTED, if DRX is configured, for all activated serving cells, the MAC entity may discontinuously monitor the PDCCHs using DRX operation; otherwise, the MAC entity may monitor the PDCCHs.

[0034] In some implementations, the RRC may control the DRX operation by setting the following parameters: · drx-onDurationTimer: This may be the duration at the start of the DRX cycle; · drx-SlotOffset: delay time before starting drx-onDurationTimer; · drx-InactivityTimer: may be the duration after which a PDCCH opportunity indicates a new UL or DL ​​transmission for the MAC entity; drx-RetransmissionTimerDL (per DL HARQ process excluding broadcast process): can be used as the maximum period until receiving a DL retransmission; drx-RetransmissionTimerUL (per UL HARQ process): may be the maximum period until receiving a grant for UL retransmission; drx-LongCycleStartOffset: Allows you to specify the long DRX cycle and the drx-StartOffset that defines the subframe in which the long or short DRX cycle starts; drx-ShortCycle(optional): Allows you to specify a short DRX cycle; drx-ShortCycleTimer (optional): the time during which the UE may perform a short DRX cycle; drx-HARQ-RTT-TimerDL (per DL HARQ process, excluding broadcast processes): can be the minimum period after which a DL allocation for HARQ retransmission is expected by the MAC entity; drx-HARQ-RTT-TimerUL (per UL HARQ process): This may be the minimum period after which a UL HARQ retransmission grant is expected by the MAC entity.

[0035] In some implementations, if a DRX cycle is configured, the (SL-DRX) active time may include the time during which: · During the execution of drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, ra-ContentionResolutionTimer (described in the 3GPP TS38 series standards), or including the following times: A scheduling request (SR) has been sent on the PUCCH and is pending (as described in the 3GPP TS38 series standards); or A PDCCH (as described in the 3GPP TS38 series of standards) indicating that no new transmissions addressed to the C-RNTI of the MAC entity have been received after successful reception of a random access response to a contention-based random access preamble that was not selected by the MAC entity.

[0036] In some implementations, when DRX is configured, the MAC entity may operate as follows: 1> If a MAC PDU is received with the configured downlink allocation 2>Start the drx-HARQ-RTT-TimerDL for the corresponding HARQ process at the first symbol after the end of the corresponding transmission carrying DL HARQ feedback. 2> Stop the drx-RetransmissionTimerDL for the corresponding HARQ process 1> When a MAC PDU is sent with the configured uplink grant 2> Start drx-HARQ-RTT-TimerUL for the corresponding HARQ process at the first symbol after the end of the first repetition of the corresponding PUSCH transmission 2> Stop the drx-RetransmissionTimerUL of the corresponding HARQ process 1> When drx-HARQ-RTT-TimerDL expires 2> If the data of the corresponding HARQ process is not successfully decoded 3>Start the drx-RetransmissionTimerDL of the corresponding HARQ process at the first symbol after the expiration of the drx-HARQ-RTT-TimerDL 1> When drx-HARQ-RTT-TimerUL expires 2> After the drx-HARQ-RTT-TimerUL expires, start the drx-RetransmissionTimerUL for the corresponding HARQ process at the first symbol. 1> When a DRX command MAC CE or a long DRX command MAC CE is received 2>Stop drx-onDurationTimer 2>Stop the drx-InactivityTimer 1> When the drx-InactivityTimer expires or a DRX command MAC CE is received 2> If a short DRX cycle is set 3>Start or restart the drx-ShortCycleTimer after the expiration of the drx-InactivityTimer or the first symbol after the end of the DRX command MAC CE reception 3> Use a short DRX cycle 2>Or 3> Use long DRX cycles 1> When drx-ShortCycleTimer ends 2> Use long DRX cycles 1> When a long DRX command MAC CE is received 2>Stop the drx-ShortCycleTimer 2> Use long DRX cycles 1> Use short DRX cycle and [(SFN x 10) + subframe number] modulo (drx-ShortCycle)=(drx-StartOffset) modulo (drx-ShortCycle); or 1> Use a long DRX cycle and [(SFN x 10) + subframe number] When modulo (drx-LongCycle)=drx-StartOffset 2> Start drx-onDurationTimer after drx-SlotOffset from the beginning of the subframe 1> When the MAC entity is in active time 2> Monitor the PDCCH as specified in the TS 2> When PDCCH indicates DL transmission 3>Start the drx-HARQ-RTT-TimerDL for the corresponding HARQ process at the first symbol after the end of the corresponding transmission carrying DL HARQ feedback. 3> Stop the drx-RetransmissionTimerDL for the corresponding HARQ process 2> When PDCCH indicates UL transmission 3> Start drx-HARQ-RTT-TimerUL for the corresponding HARQ process at the first symbol after the end of the first repetition of the corresponding PUSCH transmission 3> Stop the drx-RetransmissionTimerUL of the corresponding HARQ process 2> When PDCCH indicates a new transmission (DL or UL) 3> After PDCCH reception ends, start or restart the drx-InactivityTimer on the first symbol. 1> When evaluating all conditions for the DRX active time specified in this section for the current symbol n, it is possible that the MAC entity is not in the active time, taking into account that it received a grant / assignment / DRX command MAC CE / long DRX command MAC CE and sent an SR up to 4 ms before symbol n. 2>Do not transmit periodic SRS and semi-permanent SRS defined in TS 2> Do not report CSI on PUCCH and semi-persistent CSI on PUSCH 1> When CSI masking (csi-Mask) is configured by a higher layer 2> When evaluating all DRX active time conditions specified in this clause for the current symbol n, there is a possibility that the drx-onDurationTimer does not operate taking into account the grant / assignment / DRX command MAC CE / long DRX command MAC CE received up to 4 ms before symbol n. 3>Do not report CSI for PUCCH.

[0037] In some implementations, regardless of whether the MAC entity is monitoring the PDCCH, the MAC entity may transmit HARQ feedback, aperiodic CSI on the PUSCH, and aperiodic SRS as described in the 3GPP TS38 series standards when expected. The MAC entity may not need to monitor the PDCCH if it is not a full PDCCH opportunity (e.g., the (SL-DRX) active time starts or ends in the middle of a PDCCH opportunity).

[0038] (DRX command MAC CE) In some implementations, the DRX command MAC CE may be identified by a MAC subheader with a logical channel identification (LCID), as described in the 3GPP TS38 series standards, which may have a fixed size of 0 bits.

[0039] (Long DRX command MAC CE) In some implementations, the Long DRX Command MAC CE may be identified by a MAC subheader with an LCID as specified in the 3GPP TS, which may have a fixed size of 0 bits.

[0040] (DRX settings) In some implementations, the IE DRX-Config may be used to configure DRX-related parameters as described below: -- ASN1START -- TAG-DRX-CONFIG-START DRX-Config ::= SEQUENCE { drx-onDurationTimer CHOICE { subMilliSeconds INTEGER (1..31), milliSeconds ENUMERATED { ms1, ms2, ms3, ms4, ms5, ms6, ms8, ms10, ms20, ms3 d0, ms40, ms50, ms60, ms80, ms100, ms200, ms300, ms400, ms500, ms600, ms800, ms1000, ms1200, ms1600, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1} }, drx-InactivityTimer ENUMERATED { ms0, ms1, ms2, ms3, ms4, ms5, ms6, ms8, ms10, ms20, ms30, ms40, ms50, ms60, ms80, ms100, ms200, ms300, ms500, ms750, ms1280, ms1920, ms2560, spare9, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1}, drx-HARQ-RTT-TimerDL INTEGER (0..56), drx-HARQ-RTT-TimerUL INTEGER (0..56), drx-RetransmissionTimerDL ENUMERATED { sl0, sl1, sl2, sl4, sl6, sl8, sl16, sl24, sl33, sl40, sl64, sl80, sl96, sl112, sl128, sl160, sl320, spare15, spare14, spare13, spare12, spare11, spare10, spare9, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1}, drx-RetransmissionTimerUL ENUMERATED { sl0, sl1, sl2, sl4, sl6, sl8, sl16, sl24, sl33, sl40, sl64, sl80, sl96, sl112, sl128, sl160, sl320, spare15, spare14, spare13, spare12, spare11, spare10, spare9, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1}, drx-LongCycleStartOffset CHOICE { ms10 INTEGER(0..9), ms20 INTEGER(0..19), ms32 INTEGER(0..31), ms40 INTEGER(0..39), ms60 INTEGER(0..59), ms64 INTEGER(0..63), ms70 INTEGER(0..69), ms80 INTEGER(0..79), ms128 INTEGER(0..127), ms160 INTEGER(0..159), ms256 INTEGER(0..255), ms320 INTEGER(0..319), ms512 INTEGER(0..511), ms640 INTEGER(0..639), ms1024 INTEGER(0..1023), ms1280 INTEGER(0..1279), ms2048 INTEGER(0..2047), ms2560 INTEGER(0..2559), ms5120 INTEGER(0..5119), ms10240 INTEGER(0..10239) }, shortDRX SEQUENCE { drx-ShortCycle ENUMERATED { ms2, ms3, ms4, ms5, ms6, ms7, ms8, ms10, ms14, ms16, ms20, ms30, ms32, ms35, ms40, ms64, ms80, ms128, ms160, ms256, ms320, ms512, ms640, spare9, spare8, spare7, spare6, spare5, spare4, spare3, spare2, spare1}, drx-ShortCycleTimer INTEGER (1..16) } OPTIONAL, -- Need R drx-SlotOffset INTEGER (0..31) } -- TAG-DRX-CONFIG-STOP -- ASN1STOP.

[0041] The DRX-Config field may also be written as follows: drx-HARQ-RTT-TimerDL: This may be a value in the number of symbols of the BWP in which the transport block was received drx-HARQ-RTT-TimerUL: may be the value of the number of symbols in the BWP in which the transport block was transmitted drx-InactivityTimer: This may be an integer value multiple of 1ms. For example, ms0 corresponds to 0, ms1 corresponds to 1ms, ms2 corresponds to 2ms, and so on. drx-LongCycleStartOffset: Can contain drx-LongCycle in ms and drx-StartOffset in multiples of 1ms. If drx-ShortCycle is set, the value of drx-LongCycle may be a multiple of the value of drx-ShortCycle. drx-onDurationTimer: Can be a value of 1 / 32ms (sub-millisecond) or a multiple of ms (milliseconds). In the latter case, a value of ms1 corresponds to 1ms, a value of ms2 corresponds to 2ms, and so on. drx-RetransmissionTimerDL: This may be a value in number of slots of the BWP that received the transport block. For example, the value sl0 corresponds to 0 slots, sl1 corresponds to 1 slot, sl2 corresponds to 2 slots, etc. drx-RetransmissionTimerUL: This can be set to a value corresponding to the number of slots in the BWP in which the transport block was transmitted. For example, sl0 corresponds to 0 slots, sl1 corresponds to 1 slot, sl2 corresponds to 2 slots, and so on. drx-ShortCycleTimer: Can be a multiple of drx-ShortCycle. For example, a value of 1 corresponds to drx-ShortCycle, a value of 2 corresponds to 2 * drx-ShortCycle, and so on. drx-ShortCycle: This value can be specified in ms. For example, ms1 corresponds to 1ms, ms2 corresponds to 2ms, and so on. drx-SlotOffset: Specifies the value in multiples of 1 / 32ms. For example, a value of 0 corresponds to 0ms, a value of 1 corresponds to 1 / 32ms, a value of 2 corresponds to 2 / 32ms, and so on.

[0042] (V2X services and PC5 interface) In some implementations, vehicle-to-exchange (V2X) services may be provided to support information exchange between vehicles. V2X services include at least one of vehicle-to-infrastructure (V2I) services, vehicle-to-pedestrian (V2P) services, vehicle-to-network (V2N) services, and vehicle-to-vehicle (V2V) services. In the LTE protocol, V2X services may be supported over the air interface by the Uu interface and the PC5 interface. The PC5 interface covers Layer 2 and Layer 1 design. The air link interface of the PC5 interface is also referred to as SL in the LTE protocol. LTE networks have supported SL operation since 3GPP TS Rel. 12. Referring to FIG. 1, FIG. 1 illustrates SL operation for UEs to exchange information according to an embodiment of the present disclosure. As shown in FIG. 1, UEs can directly exchange data and control signals without the need for a BS (e.g., an eNB in ​​an LTE network or a gNB in ​​an NR network) to relay the data and control signals. For purposes of illustration, each UE in this disclosure is capable of and authorized to access V2X services via a PC5 interface with neighboring UEs and the RAN.

[0043] In some implementations, V2X services can be further classified based on different cast-types, such as: Unicast: Only two UEs in one SL group, and the formation of the SL group can be formed in the non-access stratum (NAS layer) Multicast (Groupcast): Two or more UEs can be grouped into an SL group and exchange SL packets with all other members of the SL group. In one implementation, the SL group may be formed at the NAS layer (e.g., V2X application layer or PC5-S protocol) or at the AS layer (e.g., SL RRC layer signaling, PC5-RRC signaling): Broadcast: Not restricted to SL groups. UEs can broadcast messages and neighboring UEs within SL coverage can receive and successfully decode the broadcast message. In some implementations, SL coverage may vary depending on Tx power, hardware sensitivity, etc.

[0044] In some implementations, to enable SL operation (e.g., SL operation configured to support LTE (V2X) sidelink communication, LTE sidelink discovery, LTE device-to-device (D2D) services, LTE FeD2D services, NR (V2X) SL communication, and NR SL discovery) under the coverage of a RAN (e.g., E-UTRAN or NR-RAN), a (LTE / NR) cell may provide SL configuration and SL resource allocation to a UE. For a UE under the coverage of a cellular network, the UE may need to perform SL operation based on the configuration of the RAN. To enable SL operation under the coverage of the RAN, a serving cell (or camped cell) may need to provide SL configuration and SL resource allocation to the UE. Specifically, the following two basic approaches are provided for SL resource allocation in LTE V2X services:

[0045] In one implementation, the scheduled resource allocation may be characterized as follows: · The UE may need to be in the (LTE / NR) RRC_Connected state to transmit data; The UE may request SL resources from the eNB (by sending a SL Buffer Status Report (SL-BSR) to the serving cell). The eNB schedules dedicated SL resources for the UE to transmit SCI and SL data. To achieve this, the eNB may request the UE to report the SL-BSR over the Uu interface. Furthermore, the UE may also trigger an SR on UL physical resources (e.g., PUCCH) or initiate a random access procedure if the UE wants to send a SL-BSR to the eNB but no available UL resources exist. Also, the SR resources (or configuration) and SR procedures may be common for both SL operation and uplink traffic.

[0046] In another implementation, the UE autonomous resource selection from the SL resource pool may be characterized as follows: ·UE autonomous resource selection may apply to both RRC connected UEs (e.g., through dedicated RRC signaling or through SI broadcasting) and RRC inactive / idle states (e.g., through SI broadcasting); The resource pool may be a (effectively contiguous) set of resource blocks, and the UE may autonomously decide which physical resource blocks it wants to apply to SL packet transmissions · The UE may select resources from the resource pool by itself and perform transport format selection to transmit SL control information and data; The UE may perform sensing for (re)selection of SL resources before SL packet delivery. Based on the sensing result, the UE may (re)select some specific SL resources and reserve multiple SL resources. Up to two parallel (independent) resource reservation processes may be allowed to be performed by the UE. Also, the UE may be allowed to perform a single resource selection for its V2X SL transmission.

[0047] Additionally, if the UE is out of RAN coverage on a frequency used for V2X SL communications and the BS found by the UE on that SL frequency carrier does not provide V2X SL configuration for that frequency, the UE may use a set of transmit and receive resource pools preconfigured for the UE. V2X SL communication resources may not be shared with other non-V2X data transmitted over SL. In some implementations, the UE may obtain preconfiguration through an installed Universal Mobile Telecommunications System (UMTS) Subscriber Identity Module (USIM), stored memory, or a RAN previously accessed by the UE. Furthermore, the UE can implement a PC5 interface by synchronizing with a Global Navigation Satellite System (GNSS) and applying preconfiguration. In such cases, the PC5 interface may be independent of the RAN and (LTE / NR) Uu interface.

[0048] V2X Platoon Scenario Referring to Figure 2, Figure 2 illustrates a V2X platoon scenario according to an embodiment of the present disclosure. As shown in Figure 2, platoon X may include vehicle A, vehicle B, vehicle C, and vehicle D, and there may be (at least) one scheduler (e.g., vehicle A) in the platoon. In platoon X, vehicle A may set SL resources for members of the same platoon through the following approach:

[0049] Mode 1-like approach: The scheduler may configure dynamic SL grants (e.g., dynamic SL grants via SCI) to members of the same platoon. Additionally, the scheduler may configure semi-periodic SL grants (e.g., configured SL grants) to UEs through SL control signaling (e.g., Physical Sidelink Broadcast Channel (PSBCH)) or SL RRC signaling. To achieve the Mode 1-like approach, the scheduler may require the UE to provide feedback information over one or more PC5 interfaces.

[0050] Mode 2-like approach: The scheduler can configure an SL resource pool for members of the same platoon. The UE may automatically select an SL grant by itself (e.g., SL grant selection with / without detection). The platoon scenario may apply when the vehicles of the platoon are in-coverage (i.e., all of the vehicles of the platoon are under the coverage of the cellular RAN), out-of-coverage (i.e., all of the vehicles of the platoon are outside the coverage of the cellular RAN), or partial in-coverage (i.e., some of the UEs of the platoon are in-coverage of the cellular RAN, while other UEs of the platoon are out-of-coverage of the cellular RAN).

[0051] In some implementations, to support the scheduler, members within a platoon may need to support the following in order to report their status to the scheduler via the PC5 interface: (a) SL-SR setting and reporting (b) SL-Buffer Status Report (BSR) setting and reporting ·(c) SL-Power Headroom Report (SL-PHR) setting and reporting.

[0052] Referring to FIG. 3, FIG. 3 illustrates a PC5-RRC connection between a pair of UEs according to an embodiment of the present disclosure. Specifically, the concept of a PC5-RRC connection may differ from that of an RRC connection on the Uu interface. On the NR PC5 interface, one SL-unicast group (e.g., UE#1 and UE#2 shown in FIG. 3) needs to establish (at least) one PC5-S connection, and each PC5-S connection may be independently associated with a PC5-RRC connection in the access stratum (AS stratum). In other words, a PC5-S connection and a PC5-RRC connection may have a one-to-one mapping. Each PC5 RRC connection is a logical connection between a pair of source and destination Layer 2 IDs. At the service level, one PC5-S connection (and its associated PC5-RRC connection) may be established to provide one or more SL operations (e.g., SL operations(s) to support one or more NR / LTE V2X service(s)). In some implementations, for example, PC5-S connection #1s of UE #1 and UE #2 is established to provide V2X service #1 / #2, and PC5-S connection #2s is established to provide V2X service #a / #b. Also, a pair of UEs may have multiple active PC5-S connections / PC5-RRC connections to support V2X services with different QoS requirements. In some implementations, the UE may also report the status of the PC5-RRC connection to a serving cell (e.g., a PCell of the master cell group or a PSCell of the secondary cell group), so that the serving RAN may also know the status of the PC5-RRC connection on the UE side. Furthermore, the UE may report an SL radio link failure event (for at least one PC5-RRC connection) to the serving RAN (e.g., for SL resource management, such as a Mode 1-like SL resource configuration approach). It should also be noted that a single UE may participate in multiple SL-unicast groups with different target UEs, and a single UE may have PC5-RRC connections associated with different UEs.

[0053] Sidelink - Discontinuous Reception (SL-DRX) In some implementations, the MAC entity may be configured by the RRC entity with an SL-DRX function that controls the UE's SL packet reception (e.g., physical sidelink control channel (PSCCH) monitoring) activity and / or the UE's SL packet transmission (e.g., physical sidelink shared channel (PSSCH) transmission) activity.

[0054] If SL-DRX is configured, for all associated SL (e.g., unicast, groupcast, and / or broadcast) groups, the MAC entity may discontinuously monitor the PSCCH using SL-DRX operation. Otherwise, the MAC entity may monitor the PSCCH for SL packet reception. If SL-DRX is configured, for all associated SL (e.g., unicast, groupcast, and / or broadcast) groups, the MAC entity may discontinuously transmit sidelink control information (SCI) on the PSCCH(s) configured with SL-DRX operation. Specifically, in some implementations, RRC may control the SL-DRX operation by setting the following parameters: · SL-drx-onDurationTimer: This period may be the beginning of the SL-DRX cycle; · SL-drx-SlotOffset: This delay time may be before starting SL-drx-onDurationTimer; · SL-drx-InactivityTimer: This period may be after a PSCCH opportunity where the PSCCH indicates a new SL transmission / reception of the MAC entity; · drx-RetransmissionTimerSL_Rx (e.g., for each SL-HARQ reception process for which the UE needs to send SL-HARQ feedback information to the associated SL-Tx UE): this may be the maximum period until an SL retransmission is received; · drx-RetransmissionTimerSL_Tx (e.g., per SL-HARQ transmission process for which the UE needs to retransmit a SL MAC PDU based on the SL-HARQ feedback information returned by (at least) one SL-Rx UE): this may be the maximum period until a grant for SL retransmission is received; · SL-drx-LongCycleStartOffset: This may contain the long SL-DRX cycle and the drx-StartOffset that defines the subframe in which the long and short SL-DRX cycles start; ·SL-drx-ShortCycle(optional): May include a short SL-DRX cycle; SL-drx-ShortCycleTimer (optional): allows the period during which the UE can follow a short SL-DRX cycle; · drx-HARQ-RTT-TimerSL_Rx (e.g. for each SL-HARQ reception process for which the UE needs to send SL-HARQ feedback information to the associated SL-Tx UE): this can be the minimum period until which an SL allocation for SL-HARQ reception is expected by the MAC entity; drx-HARQ-RTT-TimerSL_Tx (e.g. per SL-HARQ transmission process for which the UE needs to retransmit a SL MAC PDU based on the SL-HARQ feedback information returned by (at least) one SL-Rx UE): this may be the minimum period until which an SL-HARQ retransmission grant is expected by the MAC entity.

[0055] In some implementations, if the SL-DRX cycle is configured, the "SL-DRX" active time (for the PC5 interface) While SL-drx-onDurationTimer or SL-drx-InactivityTimer or drx-RetransmissionTimerSL_Tx or drx-RetransmissionTimerSL_Rx is running; or An SR for SL dynamic grant request has been sent and is pending on the Physical Uplink Control Channel (PUCCH) (Uu interface), or A PSCCH indicating one (or more) new transmissions addressed to (at least) one of the set of (relevant SL source IDs, SL (Layer 1 / Layer 2) destination IDs of interest) of the MAC entity UE. The time between may be included.

[0056] In some implementations, when SL-DRX is configured, the MAC entity may: 1> If a SL MAC PDU related to the UE's (associated SL source ID, interested SL destination ID) is received with the configured SL allocation 2> Start the drx-HARQ-RTT-TimerSL_Rx for the corresponding SL-HARQ process at the first symbol after the end of the corresponding transmission carrying SL-HARQ feedback (e.g., if the UE is configured to send SL-HARQ feedback information for the corresponding SL-HARQ process associated with the corresponding destination identity). 2> Stop the drx-RetransmissionTimerSL_Rx of the corresponding SL-HARQ process 1> When an SL MAC PDU is sent with a configured SL grant 2> Start drx-HARQ-RTT-TimerSL_Tx for the corresponding SL-HARQ process at the first symbol after the end (or first repetition) of the corresponding PSSCH transmission. 2> Stop the drx-RetransmissionTimerSL_Tx of the corresponding SL-HARQ process 1> When drx-HARQ-RTT-TimerSL_Rx expires 2> If the data of the corresponding SL-HARQ process is not successfully decoded 3>Start the drx-RetransmissionTimerSL_Rx of the corresponding SL-HARQ process at the first symbol after the expiration of the drx-HARQ-RTT-TimerSL_Rx 1> When drx-HARQ-RTT-TimerSL_Tx expires 2> At the first symbol after the expiration of drx-HARQ-RTT-TimerSL_Tx, start drx-RetransmissionTimerSL_Tx for the corresponding SL-HARQ process. 1> When a DRX Command MAC Control Element (CE) (or SL-DRX Command) or Long DRX Command MAC CE (or SL-Long DRX Command MAC CE) is received from the serving cell (through the Uu interface) or another UE (through the PC5 interface) 2>Stop SL-drx-onDurationTimer 2> Stop the SL-drx-InactivityTimer 1> When the SL-drx-InactivityTimer expires or a DRX command MAC CE (or SL-DRX command) is received 2> When a short SL-DRX cycle is set 3>Start or restart the SL-drx-ShortCycleTimer at the first symbol after the expiration of the SL-drx-InactivityTimer or at the first symbol after the end of reception of the DRX command MAC CE (or SL-DRX command). 3> Use a short SL-DRX cycle 2>Or 3> Use a long SL-DRX cycle 1> When SL-DRX-ShortCycleTimer ends 2> Use a long SL-DRX cycle 1> When a Long SL-DRX Command (Long DRX Command MAC CE) is received 2> Stop the SL-DRX-ShortCycleTimer 2> Use a long SL-DRX cycle 1> Use a short SL-DRX cycle and [(SFN × 10) + subframe number] modulo (SL-drx-ShortCycle) = (SL-drx-StartOffset) modulo (SL-drx-ShortCycle), or 1> When a long SL-DRX cycle is used and [(SFN × 10) + subframe number] modulo (SL-drx-LongCycle) = SL-drx-StartOffset 2> Start SL-drx-onDurationTimer after SL-drx-SlotOffset from the beginning of the subframe. 1> When the MAC entity is in (SL-DRX) active time 2) Monitor (continuously) the PSCCH of one (or more) SL frequency carriers 2> When PSCCH indicates SL transmission 3> Start the drx-HARQ-RTT-TimerSL_Rx for the corresponding SL-HARQ process at the first symbol after the end of the corresponding transmission that transmits the SL-HARQ feedback. 3> Stop the drx-RetransmissionTimerSL_Rx for the corresponding SL-HARQ process 2> When the UE transmits an SCI indicating SL transmission on one PSCCH 3> Start drx-HARQ-RTT-TimerSL_Tx for the corresponding SL-HARQ process at the first symbol after the end (or first iteration) of the corresponding PSSCH transmission 3> Stop the drx-RetransmissionTimerSL_Tx of the corresponding SL-HARQ process 2> When the PSCCH indicates a new SL packet transmission to the UE (or indicates an SL control signal), or when the UE transmits an SCI on one PSCCH 3> Start or restart the SL-drx-InactivityTimer on the first symbol after the end of the associated PSCCH.

[0057] In some implementations, the MAC entity may not need to monitor the PSCCH if it is not a full PSCCH opportunity (e.g., the (SL-DRX) active time starts or ends in the middle of a PSCCH opportunity). Also, note that in some implementations, there may be no additional SL-DRX mechanism. On the other hand, the UE may coordinate the transmission and reception of SL packets based on the SL-DRX mechanism.

[0058] It is noteworthy that the Connected Mode DRX (C-DRX) mechanism has been applied in the LTE / NR Uu interface to reduce power consumption on the UE side. However, in LTE / NR (V2X) SL operation (e.g., LTE / NR (V2X) SL communication), no similar mechanism exists to reduce power consumption on the UE side. Therefore, the definitions of SL-DRX active time, SL-DRX on period, and SL-DRX off period are introduced, and the SL-DRX mechanism is introduced to include related UE operations during the proposed SL-DRX active time (SL-DRX on period) as well as the SL-DRX off period.

[0059] Specifically, in some implementations, the mechanism may be based on the condition that the UE(s) are in an RRC connected state. It should be noted that the proposed mechanism may also be implemented for UEs in an RRC inactive state and / or an RRC idle state.

[0060] In some implementations, the mechanism may be based on the condition that the UE may be conducting SL communication under the coverage of the serving RAN (e.g., the SL unicast group, the SL multicast (groupcast) group, and the entire group are under the coverage of the serving RAN). Note that the mechanism can also be implemented when the SL unicast / multicast group is out-of-coverage (no active Uu interface with any RAN) or partially in-coverage (only a subset of group members in the group have an active Uu interface with its serving RAN (e.g., active DL / UL data or signaling exchange over the Uu interface)).

[0061] In some implementations, the mechanism may be applied based on the NR RAT (e.g., the NR Uu interface and the NR PC5 interface). It should be noted that the mechanism may also be applied to other RATs (e.g., the LTE Uu interface and the LTE PC5 interface).

[0062] In some implementations, the concept of short DRX cycle and long DRX cycle (and switch between short DRX cycle / long DRX cycle) in the C-DRX mechanism may be applicable in the SL-DRX mechanism. Indeed, it is also possible to set only the short-DRX cycle or the long-DRX cycle in the SL-DRX mechanism.

[0063] In some implementations, the SL-DRX command is sent by the serving RAN (comprising one or more serving cell(s) / BS(s) / gNB(s)) to the UE via dedicated control signaling (e.g., PHY signaling (e.g., Downlink Control Information (DCI) over PDCCH), or MAC CE or dedicated RRC signaling sent over the Physical Downlink Shared Channel (PDSCH)), or any combination of the three signaling methods, over the (LTE / NR) Uu interface.

[0064] In some implementations, the SL-DRX command may be sent by one UE (e.g., a platoon leader in an SL unicast / group-cast group) to member UEs over the PC5 interface by dedicated control signaling (e.g., MAC CE multiplexed with other SL packets in the PSSCH and / or dedicated PC5-RRC signaling (e.g., one associated PSSCH transmitted over the PSSCH)). In additional embodiments, the SL-DRX command may be delivered through (at least) one SCI in the associated PSSCH.

[0065] SL-DRX mechanism Referring to FIG. 4, FIG. 4 illustrates the configuration of SL-DRX according to an embodiment of the present disclosure. As shown in FIG. 4, in the PC5 interface, the UE may "wake up" at the start of an SL-DRX on period (or from the start of an SL-DRX active time). The UE can then execute associated / configured mechanisms during the SL-DRX on period. The UE may then switch from the SL-DRX on period (or from the SL-DRX active time) to an SL-DRX off period based on one or more defined conditions. In some implementations, the UE may stay within the SL-DRX off period for a certain period of time, and UE behavior for staying within the SL-DRX off period may also be provided in the following paragraphs. Also, as shown in FIG. 4, the SL-DRX off period may end while the UE wakes up at the start of the next SL-DRX on period.

[0066] In particular, in one implementation, the meaning of "the UE may wake up" means that the UE may start monitoring control information(s) from associated physical control channels (e.g., the UE may wake up to monitor SCI(s) (e.g., first-stage SCIs while a two-stage SCI delivery mechanism is applied) from (at least) one associated PSCCH(s) on the (LTE / NR) PC5 interface and / or the UE may wake up to monitor DCI(s) from (at least) one associated PDCCH(s) on the (LTE / NR) Uu interface). Alternatively, in one implementation, the meaning of "the UE may wake up" means that the UE may stay in a DRX (e.g., C-DRX and / or SL-DRX) active time. Alternatively, in one implementation, the meaning of "the UE may wake up" means that the UE may start the drx-onDurationTimer (and / or the SL-drx-onDurationTimer on the (LTE / NR) PC5 interface). Alternatively, in one implementation, "the UE may wake up" means that the UE may (re)start the drx-onDurationTimer (and / or the SL-drx-onDurationTimer in the (LTE / NR) PC5 interface). Alternatively, in one implementation, "the UE may wake up" means that the UE may (re)start the drx-InactivityTimer (and / or the SL-drx-InactivityTimer in the (LTE / NR) PC5 interface).

[0067] In some embodiments, one SL-DRX cycle may include one SL-DRX on period followed by an SL-DRX off period, as shown in Figure 4. Parameters for the SL-DRX mechanism (e.g., values ​​of the SL-DRX cycle / SL-DRX on period) (and control mechanisms / rules regarding UE / RAN operation during the SL-DRX active times / SL-DRX off periods within the SL-DRX cycle) may be explicitly configured by the serving RAN through broadcast messages (e.g., through an SI broadcast or SI on-demand procedure) or dedicated control signaling (e.g., an RRC (connection) reconfiguration message or other RRC messages, such as an RRC (connection) release message on the (LTE / NR) Uu interface, an RRC (connection) release message with suspend configuration, an RRC (connection) reconfiguration message without suspend configuration, an RRC (connection) setup message, an RRC (connection) request message, an RRC (connection) dormant message, etc.

[0068] In some implementations, parameters for the SL-DRX mechanism (and proposed control mechanisms / rules regarding UE / RAN behavior during the SL-DRX active time / SL-DRX off period in the SL-DRX cycle) may be configured by other UEs via the (LTE / NR) PC5 interface (e.g., through the broadcast of the SL-MIB or dedicated PC5-RRC signaling). More specifically, SL-DRX-enabled parameters (e.g., values ​​of the SL-DRX cycle / SL-DRX on period) may be configured via SL DRX configuration, which may be configured per MAC entity and / or cell group (e.g., MCG or SCG). Furthermore, the SL-DRX cycle may include a short SL-DRX cycle and / or a long SL-DRX cycle, and the UE may determine the SL-DRX cycle to apply based on predefined rules. In some implementations, the parameters for the SL-DRX mechanism (and the proposed control mechanisms / rules regarding UE / RAN behavior during the SL-DRX active time / SL-DRX off period in the SL-DRX cycle) may be pre-defined as required by the 3GPP TS38 series standards or may be pre-installed in a memory module (e.g., USIM) on the UE side.

[0069] Also, note that in some implementations, (some) of the SL-DRX parameters may be applicable in the C-DRX parameters. For such parameters, Table 1 is provided for C-DRX: ·(a) The UE may set the SL-DRX on period length = drx-onDurationTimer; ·(b) The UE can set the SL-DRX cycle length = drx-ShortCycle; (c) The long DRX cycle related design may also be applied to the SL-DRX configuration. Furthermore, in some additional embodiments, the UE may configure the long SL-DRX cycle by applying the received drx-LongCycleStartOffset received in DRX-Config.

[0070] Furthermore, in some implementations, a UE may "wake up" simultaneously on both the (LTE / NR) Uu interface and the (LTE / NR) PC5 interface. For example, one MAC entity in the UE may perform associated DRX operations for the Uu interface, while another MAC entity in the UE may perform associated SL-DRX operations for the PC5 interface. As another example, one MAC entity in the UE may jointly (simultaneously) perform the same DRX operations for both the Uu interface and the PC5 interface. And, in some embodiments, the UE may transition to a DRX-off period on the Uu interface and to a SL-DRX-off period on the PC5 interface at different times (e.g., depending on the packet exchange state (or different DRX operations) on the Uu and PC5 interfaces).

[0071] In some implementations, a UE may be configured with two C-DRX groups having two different parameter sets. Furthermore, the proposed SL-DRX mechanism may apply one or more parameters of the two different parameter sets corresponding to one of the two C-DRX groups. The selection between the different sets of parameters may be indicated by the serving RAN (e.g., through dedicated RRC signaling) or other UEs (e.g., through dedicated PC5-RRC signaling) in the same SL unicast / groupcast / broadcast group(s) as the target UE. More specifically, the two C-DRX groups may be configured for the same MAC entity and / or cell group (e.g., MCG / SCG).

[0072] [Table 1] UE behavior during SL-DRX active time (or SL-DRX on period) or SL-DRX off period In some implementations, SL-DRX may affect UE operation in the following situations: (a) SL Transmission (on PC5 interface): The UE may stop some implementations of SL packet transmission while the UE remains in the SL-DRX off period. More detailed mechanisms may be presented below. In some implementations, the UE may be configured with SL packet transmission (or short, SL packet(s)) over both the LTE PC5 interface and the NR PC5 interface. In some implementations, during the SL-DRX off period, the UE may: (1) stop SL packet transmission only over the LTE PC5 interface (thus, SL packet transmission over the NR PC5 interface can continue during the SL-DRX off period), (2) stop SL packet transmission only over the NR PC5 interface (thus, SL packet transmission over the LTE PC5 interface can continue during the SL-DRX off period), or (3) stop SL packet transmission over both the LTE PC5 interface and the NR PC5 interface. (b) SL Reception: The UE can stop some implementations of SL packet reception while the UE stays in the SL-DRX off period. More detailed mechanisms are discussed below. In some implementations, the UE may be configured to perform SL packet reception over both the LTE PC5 interface and the NR PC5 interface. In some implementations, during the SL-DRX off period, the UE may: (1) stop only SL packet reception over the LTE PC5 interface (thus, SL packet reception over the NR PC5 interface can continue during the SL-DRX off period); (2) stop only SL packet reception over the NR PC5 interface (thus, SL packet reception over the LTE PC5 interface can continue during the SL-DRX off period); or (3) stop SL packet transmission over both the LTE PC5 interface and the NR PC5 interface. (c) RAN-related SL-Uu mechanisms (at the (LTE / NR) Uu interface): The UE may stop implementing some UE reporting to the RAN while the UE remains in the SL-DRX off period (via the (LTE / NR) Uu interface) or may stop monitoring RAN commands while the UE remains in the SL-DRX off period. More detailed mechanisms may be presented below. In some implementations, the UE may use the NR Uu interface to configure SL resource configuration for both the LTE PC5 interface and the NR PC5 interface (e.g., the BS configures dynamic SL grants or SL (exceptional) resource pool configuration for the NR PC5 interface, such as for PC5 RRC connections). The BS may also configure SL (exceptional) resource pool configuration for the LTE PC5 interface. In some implementations, during the SL-DRX off period, the UE may: (1) only deactivating SL-Uu-related mechanisms associated with the LTE PC5 interface (thus, SL-Uu-related mechanisms associated with the NR PC5 interface (e.g., one or more PC5 RRC connections) may continue during the SL-DRX off period), (2) only deactivating SL-Uu-related mechanisms associated with the NR PC5 interface (thus, SL-Uu-related mechanisms associated with the LTE PC5 interface may continue during the SL-DRX off period), or (3) deactivating SL-Uu-related mechanisms associated with the LTE PC5 interface and the NR PC5 interface. (d) SL Synchronization Mechanism: Even if the UE is configured as an (LTE / NR) SyncRef UE, the UE may stop broadcasting SL-SSBs (with or without MIB-SL or MIB-SL-V2X) while the UE remains in the SL-DRX off period. Then, the UE may broadcast SL-SSBs again (with or without MIB-SL or MIB-SL-V2X) after the UE wakes up at the beginning of the SL-DRX on period (next SL-DRX cycle). A more detailed mechanism can be presented below. In some implementations, the UE can be configured as an NR SyncRef UE and an LTE SyncRef UE. In some implementations, during the SL-DRX off period, the UE can: (1) Stopping LTE SyncRef UE operation only on the LTE PC5 interface (thus, NR SyncRef UE operation on the NR PC5 interface can continue during SL-DRX off periods), (2) Stopping NR SyncRef UE operation only on the NR PC5 interface (thus, LTE SyncRef UE operation on the LTE PC5 interface can continue during SL-DRX off periods), or (3) Stopping NR SyncRef UE operation and LTE SyncRef UE operation on both the NR PC5 interface and the LTE PC5 interface, respectively, during SL-DRX off periods. (e) SL Discovery Mechanism: The UE may stop delivering LTE / NR (LTE / NR) SL discovery messages while the UE remains in an SL-DRX off period. The UE may then (re)start / resume / continue delivering (LTE / NR) SL discovery messages again after the UE wakes up at the start of a subsequent SL-DRX on period. More detailed mechanisms are discussed below. In some implementations, the UE may be configured with LTE SL discovery message delivery and NR SL discovery message delivery. In some implementations, during the SL-DRX off period, the UE may: (1) Stopping only LTE SL discovery message delivery on the LTE PC5 interface (thus, NR SL discovery message delivery on the NR PC5 interface can continue during SL-DRX off periods), (2) Stopping only NR SL discovery message delivery on the NR PC5 interface (thus, LTE SL discovery message delivery on the LTE PC5 interface can continue during SL-DRX off periods), or (3) Stopping LTE SL discovery message delivery and NR SL discovery message delivery on the LTE PC5 interface and NR PC5 interface, respectively, during SL-DRX off periods. (f) PC5-RRC Connection: In some implementations, while the UE remains in the SL-DRX off period, SL operations related to all or a subset of the PC5-RRC connections configured on the UE side (e.g., SL packet transmission / reception, PC5-RRC signal transmission / reception, or PC5-S signaling via the associated PC5-RRC connection) may be discontinued. The UE may then (re)initiate / resume / continue SL operations related to all or a subset of the PC5-RRC connections configured on the UE side while the UE remains in the SL-DRX active time. In contrast, in some additional implementations, SL operations related to SL groupcast / broadcast groups (e.g., the UE is not configured with a PC5-RRC connection with an associated target SL purpose identifier) ​​may continue regardless of whether the UE remains in the SL-DRX active time or the SL-DRX off period.

[0073] Considering the SL transmission mechanism, first, SCI transmission on the PSCCH and SL packet delivery on the PSSCH can be disclosed. In some implementations, an SL-Tx UE can be defined as a UE that wants to transmit SL data packets and / or control signals to other UEs over the (LTE / NR) PC5 interface. And, an SL-Rx UE can be defined as a UE that wants to receive SL packets and / or control signals from other UEs over the (LTE / NR) PC5 interface. In some implementations, a UE may be an SL-Tx UE or an SL-Rx UE, and the UE may switch its role between SL-Tx UE and SL-Rx UE. In other implementations, a UE can simultaneously function as both an SL-Tx UE and an SL-Rx UE. Note that the operation of an SL-Tx UE is not limited to an SL-Tx UE and may be applicable to an SL-Rx UE. Furthermore, the operation of an SL-Rx UE is not limited to an SL-Rx UE, but may also be included in an SL-Tx UE case. For example, in one implementation, a sensing procedure may generally be required of an SL-TX UE for transmission. In contrast, an SL-RX UE may also perform a sensing procedure (in a background implementation) since it may act as an SL-TX UE when requesting delivery of SL packets, although this is not intended to limit the scope of the implementation.

[0074] In some implementations, the UE may stop transmitting SCIs (e.g., the SCIs may be considered as first-stage SCIs (or referred to as first SCIs) for a two-stage SCI delivery mechanism) on the configured PSCCH(s) during the SL-DRX off period(s) (even if there is at least one pending SL packet at the UE side and there are SL resource(s) (pool) available during the SL-DRX off period(s)). Thus, the UE may not transmit SL packets (with multiplexed Decoded Reference Signals (DMRS)) on the PSSCH(s) during the SL-DRX off period(s).

[0075] In some implementations, the UE may stop accessing Type 1 SL configuration grant(s) while the UE is staying within the SL-DRX off period. (In some implementations, on the RAN side, the serving RAN may reallocate SL resources to other UEs.) In other implementations, the UE may still have access to (all or a subset of) Type 1 SL configuration grants while the UE is staying within the SL-DRX off period.

[0076] In some implementations, the UE may stop accessing "active" Type 2 SL configuration grant(s) while the UE is staying in the SL-DRX off period (so, in some implementations, on the RAN side, the serving cell may reallocate SL resources to other UEs during the UE's SL-DRX off period). In another implementation, the UE can still access (all or a subset of) the active Type 2 SL configuration grants while the UE is staying in the SL-DRX off period.

[0077] In some implementations, for Mode 2 SL resource configuration, the UE may stop accessing the SL pool(s) while the UE stays within the SL-DRX off period.

[0078] In some implementations, for SL exception resource pool(s), the UE can stop accessing the SL exception resource pool(s) while the UE is staying in the SL-DRX off period. In some implementations, the UE can continue to access the SL exceptional resource pool(s) while the UE is staying in the SL-DRX off period.

[0079] In some implementations, for SL-HARQ procedure(s), the UE may suspend ongoing (or active) SL-HARQ procedure(s) after the UE transitions to the SL-DRX off period. The UE may maintain the SL-HARQ procedure(s) suspended while the UE remains within the SL-DRX off period (e.g., the UE may suspend all active counters / timers related to the SL-HARQ procedure). For example, for SL-HARQ processes (e.g., pending packets and active SL-HARQ timers associated with one specific SL-HARQ process ID) associated with low priorities (e.g., SL logical channels with high process-per-packet priority (PPPP) thresholds, such as 7, 8, etc.), these SL logical channels with low priorities may be stopped during the SL-DRX off period. Furthermore, the PPPP threshold may be further configured for the UE (e.g., via dedicated (PC5-) RRC signaling or broadcast SI). SL aggregated MAC PDUs provided with associated PPPP values ​​higher than (and equal to) a given PPPP threshold may be considered as low-priority SL MAC PDUs. SL transmission / reception and / or SL-HARQ processes associated with the low-priority MAC PDUs may also be suspended during the SL-DRX-off period. Otherwise, assembled MAC PDUs provided with associated PPPP values ​​lower than a given PPPP threshold may be considered as high-priority SL logical channel(s). SL transmission / reception and / or SL-HARQ processes associated with these high-priority SL-HARQ processes may not be suspended during the SL-DRX-off period. In some implementations, the PPPP value of the assembled MAC PDU may be determined by the lowest PPPP value (e.g., the highest priority PPPP value) among the logical channels with pending packets included in the payload of the MAC PDU. Indeed, the implementation and mapping rules for SL logical channels and PPPP thresholds may refer to LTE V2X (SL) communications.

[0080] In some implementations, SL resources may traverse one or more SL frequency carriers over which the UE is configured to transmit SL packets (and SL control signaling, such as PC5-RRC signaling). Under such circumstances, the UE can implement the SL-DRX mechanism simultaneously across multiple SL frequency carriers. Furthermore, in some implementations, the UE may be configured with multiple SL-DRX parameter sets, each of which may apply independently to a different set of SL frequency carriers (e.g., two SL-DRX parameter sets each for FR1 (frequency carriers below 7 GHz) and FR2 (frequency carriers above 7 GHz) SL frequency carriers).

[0081] In some implementations, a subset of the SL transmission resource pool may be configured for the UE to transmit SL packets even during the SL-DRX off period. For example, a set SL-DRX-Tx resource pool configuration may be configured for the UE (e.g., through SL pre-configuration; through dedicated control signaling on the (LTE / NR) Uu interface, such as an RRC (connection) reconfiguration message; through dedicated signaling on the PC5 interface, such as PC5-RRC signaling; through broadcast messages, such as SI; or through an SI on-demand procedure). Then, after the UE transitions to the SL-DRX off period, the UE can start accessing the SL-DRX-Tx resource pool. Furthermore, in some implementations, the SL-DRX-Tx resource pool configuration may further include SL exception resource pool(s), which may be configured for the SL-Tx UE to transmit SL packets when (at least) one exception condition is met. In some implementations, the SL-DRX-Tx resource pool configuration provided for the SL-DRX active time / off period may not include the SL exception resource pool(s). It is noteworthy that in some implementations, the definition of the SL-DRX active time may only take into account the count of the SL-drx-onDurationTimer. In other words, the UE can transition directly from the SL-DRX on period to the SL-DRX off period after the SL-DRX on period timer expires (and the (SL-DRX) active time on the PC5 interface also ends). Thereafter, within one or more SL-DRX cycles, the UE may apply different sets of SL transmission resources within the SL-DRX on period and the SL-DRX off period. In some implementations, separate SL (transmission) resource pool configurations may be configured for each of the SL-DRX on period (or SL-DRX active time) and the SL-DRX off period. In some implementations, the SL (transmission) resource pool configurations configured for the SL-DRX on period (or SL-DRX active time) and the SL-DRX off period may be isolated from each other in physical resource block (PRB) allocation.In some implementations, the SL (transmission) resource pool configurations configured for the SL-DRX on period (or SL-DRX active time) and the SL-DRX off period may partially overlap in PRB allocation.

[0082] In some implementations, while the UE is in the SL-DRX off period, the UE can stop transmitting PC5-RRC signals to peer UEs. The PC5-RRC signaling may then be buffered in the SL-Tx UE. The SL-Tx UE may restart transmitting PC5-RRC signals in the next SL-DRX on period. Therefore, while the UE is in the PC5 off period, some specific procedures (e.g., SL UE capability inquiry / exchange signaling and SL resource (pool) configuration / inquiry procedures on the PC5 interface) may also be suspended. Also, RRC procedures related to these PC5-RRC signaling may be suspended while the UE is in the SL-DRX off period. Furthermore, active / on-going counters or timers related to these suspended PC5-RRC procedures may also be suspended during the SL-DRX off period. The UE may then re-count the suspended counters / timers after the UE transitions back to the SL-DRX on period.

[0083] In some implementations, the SL resources for SL transmission may include one or more SL frequency carriers on which the UE may monitor SL packet transmissions.

[0084] In some implementations, for a UE staying in an SL-DRX off period, the UE may determine whether to switch to an SL-DRX on period based on whether there may be pending SL packets (SL control signaling) at the UE side (e.g., start the SL-DRX on period timer after SL-DRX-slot offset (≧0) from the start of the corresponding subframe on the PC5 interface). That is, the UE may transition from the SL-DRX off period to the SL-DRX on period at the start of the SL-DRX cycle (and start the SL-DRX on duration timer from the beginning of the corresponding subframe (after SL-DRX-SlotOffset)) if there are one or more pending SL packets in the buffer. In contrast, the UE may decide to stay in the SL-DRX off period (and not start the SL-DRX-onDurationTimer after SL-drx-SlotOffset from the beginning of the corresponding subframe) if there are no pending packets in the buffer.

[0085] Second, a sensing mechanism may be disclosed to take the SL transmission mechanism into account. In some implementations, an SL-Tx UE can implement an SL sensing or partial sensing mechanism to select target SL resource blocks for SL packet delivery in LTE V2X SL communications and NR SL operations.

[0086] In some embodiments, the UE may stop implementing SL sensing or partial sensing mechanisms during the SL-DRX off period.

[0087] Referring to Figure 5(a), Figure 5(a) illustrates a sidelink detection window according to an embodiment of the present disclosure. In some implementations, a UE may be configured with a "sidelink (SL) detection window" period during an SL-DRX-off period. As shown in Figure 5(a), before the start of an SL-DRX-on period, the UE may begin to proactively implement SL detection or partial detection mechanisms in preparation for SL packet delivery in the upcoming SL-DRX-on period.

[0088] Based on FIG. 5(a), in some implementations, a UE may monitor and decode a PSCCH located within the SL detection window. In some implementations, the UE may not decode the PSCCH or SCI within the PSSCH during the SL detection window. Instead, the UE may monitor the received signal strength (e.g., SL-RSSI) or received power density (e.g., SL-RSRQ) of the PSCCH (e.g., by detecting each physical resource block associated with the PSCCH(s)) or may only monitor the PSSCH(s) within the configured SL detection window. In some implementations, the UE may monitor a power save signal (PSS) (or a wake-up signal (WUS)) within the (LTE / NR) Uu interface for SL during the SL detection window. The UE may then wake up on the (LTE / NR) PC5 interface after receiving the PSS (or WUS) from the serving cell over the Uu interface.

[0089] More specifically, in some implementations, the PSS may be referred to as a WUS, a PDCCH-WUS, a PDCCH-skipping, and / or a go-to-sleep signal. The PSS may be scrambled by a unique RNTI (e.g., a power-saving RNTI (PS-RNTI)). The PSS may include one or more of the following collections of information, which does not limit the scope of the present embodiments: C-DRX (e.g., awake and / or go to sleep state), cross-slot scheduling, trigger reference signal transmission, CSI-RS measurement report, single / multi-cell operation, bandwidth part information (e.g., BWP ID), secondary cell (SCell) information (e.g., SCell ID), multiple-input multiple-output (MIMO) layer adaptation (e.g., maximum number of MIMO layers), number of antennas, indication of control resource set (CORESET) / search space / candidates for subsequent PDCCH decoding, PDCCH monitoring periodicity, PDCCH skip, number of skips for C-DRX monitoring, SPS (Semi-Persistent Scheduling) activation, C-DRX configuration, C-DRX period, etc. The PSS monitoring opportunity can be "instructed" to the UE by the NW before and / or at the start (e.g., of the start symbol / slot / subframe) of the C-DRX on period. Instructing the UE may include explicit signaling by higher layer signaling or via a CORESET / search space. For example, the serving RAN may configure an offset to the UE. The serving RAN can configure a specific CORESET and / or search space for the PSS. The serving RAN can configure a specific periodicity for the PSS, e.g., the periodicity can be associated with the periodicity of the DRX cycle. The UE can monitor the PSS at an offset before and / or at the start (e.g., start symbol / slot / subframe) of the C-DRX on period on a specific CORESET and / or search space. The WUS may have a field to indicate whether the UE should wake up or not wake up in the upcoming new C-DRX cycle.Alternatively, the WUS may not have an explicit field / format for indicating whether the UE needs to wake up or not. When the UE receives the WUS, it may mean that the serving RAN instructs the UE to wake up (e.g., to monitor the PDCCH on the subsequent C-DRX on period (i.e., so that the UE may start the drx-OnDurationTimer at the start of the subsequent C-DRX period)). If the UE does not receive the WUS on the WUS opportunity, it may mean that the serving RAN instructs the UE not to wake up (e.g., not to monitor the PDCCH and to remain in the C-DRX off period (i.e., not to start the drx-onDurationTimer at the start of the subsequent C-DRX period)).

[0090] In some implementations, the UE can decide whether to start the (partial) detection mechanism at the beginning of the SL detection window based on whether the UE has pending SL packets in its buffer. For example, the UE can start the (partial) detection mechanism only if there are pending SL packets on the SL-Tx UE side. In contrast, if the UE has no pending packets in its buffer, the UE cannot trigger the SL (partial) detection mechanism and the SL detection window. Instead, the UE can decide whether to continue monitoring during the detection window based on a specific indication (e.g., for PSS and / or WUS), which may be indicated during the detection window.

[0091] Referring to Figure 5(b), Figure 5(b) illustrates another sidelink detection window according to an example implementation of the present disclosure. It should be noted that, as shown in Figure 5(b), in some implementations, the SL detection window may be configured as part of the SL-DRX on period. In other words, the UE may initiate the SL (partial) detection mechanism only when the UE wakes up at the beginning of the SL-DRX on period. Furthermore, the UE may determine whether to transmit an SL packet in this SL-DRX on period based on the (partial) detection result.

[0092] Referring to Figure 5(c), Figure 5(c) illustrates another sidelink detection window according to one embodiment of the present disclosure. As shown in Figure 5(c), in some implementations, the UE may initiate the SL (partial) detection mechanism while a new SL packet arrives in the UE-side buffer while the UE is in the SL-DRX off period. Furthermore, the UE may apply this rule only if the new SL packet(s) belong to a specific (pre-configured) SL logical channel (e.g., a logical channel with a high priority, such as an SL logical channel associated with a low PPPP value / threshold), some specific PPPP threshold, or some specific PPPP value.

[0093] In some implementations, an SL-Tx UE may be configured to implement either a detection mechanism based on the SL-DRX mechanism or a partial detection mechanism. For example, an SL-Tx UE may implement a (partial) detection mechanism during an SL-DRX on period. In contrast, an SL-Tx UE may implement a partial detection mechanism while staying in an SL-DRX off period. Furthermore, the detection mechanism may not be suspended during the transition between an SL-DRX on period and an SL-DRX off period. In some implementations, the UE may stop the (partial) detection mechanism while the UE switches from an SL-DRX on period (or SL-DRX active time) to an SL-DRX off period, or while the UE switches from a C-DRX on period (or C-DRX active time) to a C-DRX off period. Furthermore, the UE may release the stored detection results when the (partial) detection mechanism is stopped.

[0094] Third, the SL transmission mechanism may include channel busy ratio (CBR) measurements and channel occupancy.

[0095] To initiate CBR measurements, in some implementations, the UE may stop performing CBR measurements during the SL-DRX off period. In some implementations, the UE may be configured with another SL CBR window that also follows the SL detection window shown in Figures 5(a)-5(c). In some implementations, CBR measurements may not be interrupted while the UE switches from an SL-DRX on period (or SL-DRX active time) to an SL-DRX off period and / or while the UE switches from an SL-DRX off period to an SL-DRX active time (or SL-DRX on period).

[0096] Next, to take channel occupancy into account, in some implementations, the UE may stop performing channel occupancy measurements during SL-DRX off periods. In some implementations, the UE may be configured with another SL channel occupancy window that also follows the SL detection window shown in Figures 5(a) to 5(c). In some implementations, channel occupancy measurements may not be interrupted while the UE switches from an SL-DRX on period (or SL-DRX active time) to an SL-DRX off period and / or while the UE switches from an SL-DRX off period to an SL-DRX on period (or SL-DRX active time).

[0097] Fourth, the SL transmission mechanism may include an SL-BSR procedure. In some implementations, UEs may exchange SL-BSR(s) over the NR PC5 interface (e.g., through PC5-RRC signaling). In some implementations, one UE may not initiate an SL-BSR to a neighboring UE over the PC5 interface while the UE remains within the SL-DRX off period. In some additional implementations, one ongoing SL-BSR procedure may be put on hold / paused / deferred / cancelled during the SL-DRX off period. In some implementations, the UE can still initiate an SL-BSR procedure to a neighboring UE over the PC5 interface while the UE remains within the SL-DRX off period. Furthermore, ongoing SL-BSR procedures may not be affected by switching / transitioning between the SL-DRX on and SL-DRX off periods.

[0098] Fifth, the SL transmission mechanism may include an SL-SR procedure. In some implementations, the UE may initiate an SL-SR procedure with (at least) one neighboring UE over the PC5 interface (e.g., through PC5-RRC signaling). In some additional implementations, an ongoing SL-SR procedure may be put on hold / paused / postponed / cancelled during an SL-DRX off period. In some implementations, the UE may not initiate an SL-SR to a neighboring UE over the PC5 interface while the UE is staying within the SL-DRX off period. In some implementations, the UE can still initiate an SL-SR procedure to a neighboring UE over the PC5 interface while the UE is staying within the SL-DRX off period. Furthermore, an ongoing SL-SR procedure may not be affected by switching / transitioning between SL-DRX on / SL-DRX off periods.

[0099] Sixth, the SL transmission mechanism may include an SL-Power Headroom Report (SL-PHR) procedure. In some implementations, the UE can initiate an SL-PHR procedure with at least one neighboring UE over the PC5 interface (e.g., through PC5-RRC signaling). In some implementations, the UE may not initiate an SL-PHR procedure for neighboring UEs over the PC5 interface while the UE remains in the SL-DRX off period. In some additional implementations, an ongoing SL-PHR procedure may be held / suspended / postponed / cancelled during the SL-DRX off period. In some implementations, the UE can still initiate an SL-PHR procedure for neighboring UEs over the PC5 interface while the UE is in the SL-DRX off period. Furthermore, an ongoing SL-PHR procedure may not be affected by switching / transitioning between SL-DRX on / SL-DRX off periods.

[0100] Seventh, the SL transmission mechanism may include exception conditions. In some implementations, the UE may break the rule of stopping SL packet transmission (through an SL dynamic grant, a Type 1 SL configured grant, a Type 2 SL configured grant, a Mode 2 SL resource pool configuration, or an exception resource pool) while (at least) one exception condition occurs, for example, as follows: (a) The (NR / LTE) RRC protocol T310 or T311, as commonly known and defined in the 3GPP TS38 series standards, is being executed; (b) T301 of the (NR / LTE) RRC protocol, as commonly known and defined in the 3GPP TS38 series of standards, is being executed; (c) T304 of the (NR / LTE) RRC protocol as commonly known and defined in the 3GPP TS38 series standards is being executed; · (d) if (partial) sensing results regarding the SL resource (pool) configured for the UE are not yet available; (e) From the time the UE initiates an (NR / LTE) RRC connection (re)establishment / resumption until it receives an RRC (connection) reconfiguration including SL resource (pool) configuration or an RRC (connection) release (e.g., an RRC (connection) release message with or without suspend configuration or an RRC (connection) reject message instructing the UE to move to the (LTE / NR) RRC INACTIVE state); · (f) If the UE is initiated to send PC5-RRC signaling (e.g., an SL-SR procedure, an SL-BSR procedure, or an SL-PHR procedure) to another UE via the PC5 interface while staying in the SL-DRX off period, or if the UE is initiated to send an SL SR request procedure, a BSR procedure, or an SL PHR procedure to the UE's serving cell via the (LTE / NR) Uu interface.

[0101] In some implementations, the SL-DRX off period ends during the occurrence of (at least) one of the above exception conditions, after which the UE may wake up to transition to the next SL-DRX on period (e.g., the UE may start the SL-DRX on period timer SL-DRX-SlotOffset (≧0) from the beginning of the corresponding subframe in the relevant (LTE / NR) PC5 interface).

[0102] With regard to SL reception, this may include SCI reception on the PSCCH and SL packet delivery on the PSSCH. In some implementations, the UE may not monitor the first stage SCI (also referred to as the first SCI) on the PSCCH and the next associated PSSCH from the available SL resources while the UE is in the SL-DRX off period. The available SL resources may include the entire SL reception resource pool. Furthermore, the UE may not monitor the second stage SCI (also referred to as the second SCI) that may be delivered on the PSSCH during the SL-DRX off period while the second stage SCI is implemented on the PC5 interface.

[0103] Also, note that the SL reception resource pool may include one or more SL frequency carriers that the UE may monitor for SL packet reception.

[0104] It is noteworthy that in some implementations, a subset of the SL reception resource pool may be configured for the UE to monitor even during the SL-DRX-off period. For example, one set of SL-DRX-Rx resource pool configurations may be configured for the UE (e.g., via SL pre-configuration; by dedicated control signaling on the Uu interface such as an RRC (connection) reconfiguration message; by dedicated signaling on the PC5 interface such as PC5-RRC signaling; by broadcast messages such as SI; or by an SI-on-demand procedure). Then, the UE may start monitoring the SL-DRX-Rx resource pool after transitioning to the SL-DRX-off period. Then, the UE can monitor the entire configured SL reception resource pool after the UE transitions to the SL-DRX-on period in the next SL-DRX cycle. Furthermore, in some implementations, the proposed SL-DRX-Rx resource pool configuration may further include SL exception resource pool(s), which are configured for the SL-Tx UE to transmit SL packets when (at least) one of the above exception conditions is met. Also, note that in some implementations, the definition of the SL-DRX active time may only consider the count of the SL-drx-onDurationTimer. In other words, the UE may transition directly from the SL-DRX on period to the SL-DRX off period after the SL-DRX on period timer expires (and the (SL-DRX) active time on the PC5 interface also expires). Thereafter, within the SL-DRX cycle, the UE can apply different sets of SL receive resource pools within the SL-DRX on period or the SL-DRX off period. Also, note that in some implementations, the SL receive resource pool(s) for the SL-DRX on period and the SL-DRX off period may be independently configured and separated in the PRB allocation. In some implementations, the SL receive resource pool(s) for the SL-DRX on period and the SL-DRX off period may (partially) overlap in the PRB allocation.

[0105] Regarding SL-Uu-related mechanisms for the RAN, they may include SL dynamic grant monitoring. In some implementations, the UE may not monitor the PDCCH (or the search space / CORESET configured for SL dynamic grant reception) while the UE is staying in the SL-DRX off period (e.g., the search space / CORESET configured for SL dynamic grant reception). Thus, the UE may not attempt to decode the PDCCH using the RNTI configured for SL dynamic grant reception (e.g., the SL-RNTI / sl-RNTI). In some implementations, the UE can still monitor the PDCCH from the serving RAN during the (SL-DRX) active time on the Uu interface even if the UE is staying in the SL-DRX off period on the PC5 interface. In some implementations, the UE may not monitor the PDCCH only when the UE is staying in the SL-DRX off period and the C-DRX off period.

[0106] Second, SL-Uu-related mechanisms for the RAN may include SL (Type 2) configured grant activation / deactivation. In some implementations, the UE may not monitor the PDCCH while the UE is in the SL-DRX off period(s). (For example, if the UE is configured with a Type 2 SL configured grant, the UE may not monitor the PDCCH for SL configured grant activation / deactivation from the serving RAN.) Therefore, the UE may not attempt to decode the PDCCH using the RNTI (e.g., SL-CS-RNTI / sl-CS-RNTI) configured for the SL configured grant activation / deactivation. In some implementations, the UE may still monitor the PDCCH (or search space / CORESET configured for SL configuration grant(s)(de)activation) (e.g., for SL configuration grant activation / deactivation from the serving RAN) during the (SL-DRX) active time on the Uu interface, even when the UE stays in the SL-DRX off period on the PC5 interface. In some implementations, the UE may not monitor the PDCCH / search space / CORESET (e.g., for SL configuration grant activation / deactivation from the serving RAN) only while the UE stays in the SL-DRX off period and the C-DRX off period.

[0107] Third, SL-Uu-related mechanisms for the RAN may include SL-SR (Uu interface) for SL packet delivery. In some implementations, the UE may not trigger SL-SR procedure(s) (e.g., over the Uu interface) for SL logical channel(s) for the serving RAN while the UE is in an SL-DRX off period. In some implementations, the UE may trigger SL-SR procedure(s) for SL LCH(s) for the serving RAN during the (SL-DRX) active time on the Uu interface, even if the UE is in an SL-DRX off period on the PC5 interface. In some implementations, the UE may not initiate SL SR to its serving cell over the Uu interface, even when the UE is in a C-DRX off period (and / or SL-DRX off period). In some implementations, the UE may suspend / stop / release / delete / remove all or a subset of ongoing SL-SR procedures related to the serving RAN on the (LTE / NR) Uu interface during the SL-DRX off period.

[0108] Fourth, SL-Uu-related mechanisms to the RAN may include SL-BSR (Uu interface) for SL packet delivery. In some implementations, the UE may not initiate SL-BSR procedure(s) to report BSRs for SL LCH(s) to the serving RAN while the UE is staying in an SL-DRX off period. In some implementations, the UE may report BSRs for SL LCH(s) to the serving RAN during the (SL-DRX) active time on the Uu interface, even if the UE is staying in an SL-DRX off period on the PC5 interface. In some implementations, the UE may not initiate SL-BSR to the UE's serving cell over the Uu interface while the UE is staying within a C-DRX off period (and / or SL-DRX off period). In some implementations, the UE may suspend / stop / release / delete / remove all or a subset of ongoing SL-BSR procedures associated with the serving RAN on the (LTE / NR) Uu interface during the SL-DRX off period.

[0109] Fifth, SL-Uu-related mechanisms to the RAN may include SL-PHR (Uu interface) for SL packet delivery. In some implementations, the UE may not initiate SL-PHR procedure(s) to report PHR to the serving RAN while the UE is in an SL-DRX off period. In some implementations, the UE may trigger an SL-PHR procedure to the serving RAN during the (SL-DRX) active time on the Uu interface, even if the UE is in an SL-DRX off period on the PC5 interface. In some implementations, the UE may not initiate SL PHR to the UE's serving cell over the Uu interface while the UE is in a C-DRX off period (and / or SL-DRX off period). In some implementations, the UE may suspend / stop / release / delete / drop all or a subset of ongoing SL-PHR procedures associated with the serving RAN on the (LTE / NR) Uu interface during the SL-DRX off period.

[0110] Sixth, SL-Uu-related mechanisms for the RAN may include SL-HARQ feedback information on the Uu interface. In some implementations, the UE may not transmit SL-HARQ feedback information to the serving RAN while the UE is in an SL-DRX off period. In some implementations, the UE may transmit SL-HARQ feedback to the serving RAN during the (SL-DRX) active time on the Uu interface, even if the UE is in an SL-DRX off period on the PC5 interface. In some implementations, the UE may not transmit SL-HARQ feedback information to the serving RAN only while the UE is in a C-DRX off period (and / or an SL-DRX off period). In some implementations, the UE may suspend / stop / release / delete / remove all or a subset of ongoing SL-HARQ feedback procedures associated with the serving RAN on the (LTE / NR) Uu interface during the SL-DRX off period.

[0111] Regarding the SL synchronization mechanism, the SL synchronization mechanism may include SL synchronization sequence distribution. In some implementations, a UE may become a SyncRef UE and continuously broadcast SL synchronization messages (e.g., SL synchronization sequence block set (SL-SSB set) and SL-MIB / SL-MIB-V2X). In some implementations, the UE may stop / suspend / defer / stop / release / delete / remove transmission of SL synchronization messages while the UE stays in an SL-DRX off period. The UE may then continuously transmit SL synchronization messages after the UE transitions to an SL-DRX on period again. In some implementations, a SyncRef UE may continue to continuously broadcast an SL-SSB set and its associated SL-MIB / SL-MIB-V2X (e.g., over the PSBCH) unaffected by transitions between SL-DRX on and SL-DRX off periods.

[0112] For SL discovery, it may include an SL discovery message transmission mechanism. In some implementations, for the (LTE / NR) SL discovery mechanism, the UE may be configured to transmit / receive SL discovery messages. The content of the SL discovery messages may be provided by a higher layer (e.g., the application layer / V2X layer). The SL discovery messages may be transmitted on a specific physical sidelink discovery channel (PSDCH) or a common PSSCH. In some implementations, (e.g., for some commercial SL discovery services), the UE may stop transmitting SL discovery messages while the UE is in an SL-DRX off period. Then, after the UE transitions again to an SL-DRX on period (or SL-DRX active time), the UE may continuously retransmit the SL discovery messages. In some implementations, if the SL discovery messages are for a specific service (e.g., for public safety services), the UE may continue to deliver the SL discovery messages continuously without being affected by the switching / transition between the SL-DRX on period and the SL-DRX off period.

[0113] Next, SL discovery may include an SL discovery message reception mechanism. In some implementations (e.g., for some commercial SL discovery services), the UE can stop / suspend / postpone / delete / release monitoring of SL discovery messages while the UE is in an SL-DRX off period. Then, after the UE transitions to an SL-DRX on period again, the UE may start continuous monitoring for SL discovery messages again. In some implementations, if the SL discovery messages are for a specific service (e.g., for a public safety service), the UE can continue to continuously monitor for SL discovery messages without being affected by switching / transitioning between the SL-DRX on period and the SL-DRX off period.

[0114] Counters / timers related to the SL-DRX mechanism Some implementations may include details of UE behavior in the following situations: ·(a) UE actions to trigger the UE to switch from a SL-DRX off period to a SL-DRX on period; · (b) UE behavior while the UE is staying in the SL-DRX on period; ·(c) UE actions to trigger the UE to switch from the SL-DRX on period (or SL-DRX active time) to the SL-DRX off period; ·(d) UE behavior while the UE is in the SL-DRX active time (for Uu interface and / or PC5 interface).

[0115] Specifically, the more detailed UE operation during the SL-DRX on period can be shown as follows: On the UE side, the RRC sublayer can control the SL-DRX operation by setting the following parameters: · SL-DRX-onDurationTimer: This allows the duration at the beginning of the SL-DRX cycle; ·SL-drx-SlotOffset: Specifies the delay time before starting SL-drx-onDurationTimer; · SL-drx-InactivityTimer: This may be the period after a PSCCH opportunity where the PSCCH indicates a new SL transmission or reception for that MAC entity; · drx-RetransmissionTimerSL_Rx (e.g., for each SL-HARQ reception process for which the UE needs to send SL-HARQ feedback information to the associated SL-Tx UE): this may be the maximum period until an SL retransmission is received; · drx-RetransmissionTimerSL_Tx (e.g., per SL-HARQ transmission process for which the UE needs to retransmit a SL MAC PDU based on the SL-HARQ feedback information returned by (at least) one SL-Rx UE): may be the maximum duration until receiving an SL grant for SL retransmission; · SL-drx-LongCycleStartOffset: This may contain the long SL-DRX cycle and the drx-StartOffset that defines the subframe in which the long and short SL-DRX cycles start; ·SL-drx-ShortCycle(optional): This can include a short SL-DRX cycle; · SL-drx-ShortCycleTimer (optional): the time that the UE can follow the short SL-DRX cycle; · drx-HARQ-RTT-TimerSL_Rx (e.g., for each SL-HARQ reception process for which the UE needs to send SL-HARQ feedback information to the associated SL-Tx UE): this may be the minimum period until an SL allocation for SL-HARQ reception is expected by the MAC entity; · drx-HARQ-RTT-TimerSL_Tx (e.g. per SL-HARQ transmission process for which the UE needs to retransmit a SL MAC PDU based on SL-HARQ feedback information returned by (at least) one SL-Rx UE): this could be the minimum period until which an SL-HARQ retransmission grant is expected by the MAC entity.

[0116] In some implementations, the UE can receive the configuration values ​​for the above parameters through SL pre-configuration; through dedicated control signaling on the (LTE / NR) Uu interface, such as an RRC (connection) reconfiguration message; through dedicated signaling on the (LTE / NR) PC5 interface, such as PC5-RRC signaling; or through a broadcast message such as SI (e.g., via an (NR / LTE) V2X dedicated SIB), on the Uu interface, via an SI on-demand procedure).

[0117] In some implementations, if the SL-DRX cycle is configured on the PC5 interface, the (SL-DRX) active time on the PC5 interface is While SL-drx-onDurationTimer, SL-drx-InactivityTimer, drx-RetransmissionTimerSL_Tx, or drx-RetransmissionTimerSL_Rx is running; or An SR for SL dynamic grant request has been sent on PUCCH (Uu interface) and is pending, or · A PSCCH indicating one or more new transmissions addressed to (at least) one of the set (relevant SL source IDs, interested SL destination IDs) of the MAC entity UE, It may include the time during which

[0118] Considering the SL-DRX-onDurationTimer, first, it may be disclosed that in some implementations, the UE may start counting the SL-DRX-onDurationTimer while the UE is awake at the start of the SL-DRX on period (e.g., after SL-DRX-SlotOffset from the start of the subframe).

[0119] Considering the SL-DRX-onDurationTimer again, it can be disclosed that in some implementations, the UE may stop counting the SL-DRX-onDurationTimer when a (SL)DRX command MAC CE (or SL-DRX command) or a Long DRX command MAC CE (or SL-Long DRX command MAC CE) is received from the serving cell. Of note, in some implementations, the UE may receive the (SL)DRX command MAC CE or SL-DRX command from the serving RAN over the (LTE / NR) Uu interface. In some implementations, the UE may receive the DRX command MAC CE or SL-DRX command from another UE (e.g., a platoon leader or an SL scheduler) over the (LTE / NR) PC5 interface. In some implementations, the SL-DRX command or SL-Long DRX command on the (LTE / NR) PC5 interface may be included in one or more PC5-RRC signaling or SCI between UEs.

[0120] Considering the SL-drx-onDurationTimer again, in some implementations, the UE starts the SL-drx-onDurationTimer SL-drx-SlotOffset after the beginning of the subframe if a long SL-DRX cycle is applied, and can make [(SFN × 10) + subframe number] modulo (SL-drx-LongCycle) = SL-drx-StartOffset in the associated (LTE / NR) PC5 interface. Note also that the subframe number may be associated with a subframe number that the UE obtains from the serving RAN over the (LTE / NR) Uu interface, or may be associated with a subframe number that the UE obtains from another UE over the (LTE / NR) PC5 interface.

[0121] Next, the SL-DRX-InactivityTimer: In some implementations, the UE may (continuously) monitor the PSCCH for one or more SL frequency carriers when the MAC entity is in PC5 active time (or so-called SL-DRX active time). In some implementations, the SL-DRX off period may also be called PC5 off period). Then, if one monitored PSCCH indicates a new SL packet transmission to the UE (or indicates an SL control signal), or if the UE sends an SCI on one PSCCH, the UE may start or restart the SL-DRX-InactivityTimer at the first symbol after the end of the associated PSCCH.

[0122] Also, for the UE side, the following mechanisms / behaviors may be described: 1> When the SL-DRX-InactivityTimer expires or a DRX command MAC CE (or SL-DRX command) is received 2> When a short SL-DRX cycle is set 3>Start or restart the SL-drx-ShortCycleTimer at the first symbol after the expiration of the SL-drx-InactivityTimer or at the first symbol after the end of reception of the DRX command MAC CE (or SL-DRX command). 3> Use a short SL-DRX cycle (UE may switch from SL-DRX on period or SL-DRX active time to SL-DRX off period) 2>Or 3> Use a long SL-DRX cycle (and the UE may switch from an SL-DRX on period or an SL-DRX active time to an SL-DRX off period).

[0123] Again, considering the SL-drx-InactivityTimer, in some implementations, a UE may stop counting the SL-drx-InactivityTimer when a DRX command MAC CE (or SL-DRX command) or a Long DRX command MAC CE (SL-Long DRX Command MAC CE) is received from the serving cell. Also, note that in some implementations, a UE can receive a DRX command MAC CE or an SL-DRX command from the serving RAN over the (LTE / NR) Uu interface. In some implementations, a UE may receive a DRX command MAC CE or an SL-DRX command from another UE (e.g., a platoon leader or an SL scheduler) over the (LTE / NR) PC5 interface. In some implementations, an SL-DRX command or an SL-Long DRX command on the (LTE / NR) PC5 interface may be included in one or more PC5-RRC signaling messages between UEs.

[0124] Third, considering drx-HARQ-RTT-TimerSL_Rx and drx-RetransmissionTimerSL_Rx, firstly, on the UE side, in some implementations, the MAC entity may configure the following behavior / mechanism during (SL-DRX) active time: 2> The UE may then (continuously) monitor the PSCCH of one (or more) SL frequency carriers 2> If one received PSCCH indicates SL transmission 3> The UE may start the drx-HARQ-RTT-TimerSL_Rx for the corresponding SL-HARQ process at the first symbol after the end of the corresponding UE transmission carrying SL-HARQ feedback (note also that in some implementations the UE may not start the drx-HARQ-RTT-TimerSL_Rx if the UE is not configured to send SL-HARQ feedback for the corresponding SL Purpose Identity). 3>The UE may then stop the drx-RetransmissionTimerSL_Rx for the corresponding SL-HARQ process.

[0125] In some implementations, considering again the drx-HARQ-RTT-TimerSL_Rx and drx-RetransmissionTimerSL_Rx, on the UE side, if SL-DRX is configured, the MAC entity may: 1> If a SL MAC PDU related to the UE's (associated SL source identity, source identity of interest) is received with the configured SL allocation 2> The UE may start the drx-HARQ-RTT-TimerSL_Rx for the corresponding SL-HARQ process at the first symbol after the end of the corresponding transmission carrying SL-HARQ feedback (e.g., if the UE is configured to send SL-HARQ feedback information for the corresponding SL-HARQ process associated with the corresponding destination identity). 2>The UE may then stop the drx-RetransmissionTimerSL_Rx of the corresponding SL-HARQ process.

[0126] In some implementations, considering again the drx-HARQ-RTT-TimerSL_Rx and drx-RetransmissionTimerSL_Rx, on the UE side, when SL-DRX is configured, the MAC entity may: 1> When the drx-HARQ-RTT-TimerSL_Rx expires and the data of the corresponding SL-HARQ process is not successfully decoded 3> The UE may start the drx-RetransmissionTimerSL_Rx for the corresponding SL-HARQ process at the first symbol after the expiration of the drx-HARQ-RTT-TimerSL_Rx.

[0127] Fourth, taking into account the drx-HARQ-RTT-TimerSL_Tx and drx-RetransmissionTimerSL_Tx, in some implementations, the following behaviors / mechanisms may be configured for the UE side when SL MAC PDUs are transmitted in the configured sidelink grant: 2> The UE may start the drx-HARQ-RTT-TimerSL_Tx for the corresponding SL-HARQ process at the first symbol after the end of transmission (or first repetition) of the corresponding PSSCH transmission. 2>The UE may then stop the drx-RetransmissionTimerSL_Tx for the corresponding SL-HARQ process.

[0128] In some implementations, considering again the drx-HARQ-RTT-TimerSL_Tx and drx-RetransmissionTimerSL_Tx, on the UE side, expiry of the drx-HARQ-RTT-TimerSL_Tx may render the following behavior / mechanism: 2> The UE may start the drx-RetransmissionTimerSL_Tx for the corresponding SL-HARQ process at the first symbol after the expiration of the drx-HARQ-RTT-TimerSL_Tx.

[0129] In some implementations, taking into account again the drx-HARQ-RTT-TimerSL_Tx and drx-RetransmissionTimerSL_Tx, for the UE side, if the MAC entity is in (PC5) (SL-DRX) active time and the UE sends an SCI indicating SL transmission on one PSCCH, the following behavior / mechanism can be rendered: 3> The UE may start the drx-HARQ-RTT-TimerSL_Tx for the corresponding SL-HARQ process at the first symbol after the end of the first repetition of the corresponding PSSCH transmission, and 3>The UE may then stop the drx-RetransmissionTimerSL_Tx for the corresponding SL-HARQ process.

[0130] Fifth, considering the SL-drx-ShortCycle and SL-drx-ShortCycleTimer in some implementations, the following behaviors / mechanisms may be disclosed for UEs staying in the SL-DRX on period: 1> When the SL-drx-InactivityTimer expires or a DRX command MAC CE (or SL-DRX Command) is received 2> When a short SL-DRX cycle is set 3> The UE may start or restart the SL-drx-ShortCycleTimer at the first symbol after the expiration of the SL-drx-InactivityTimer or at the first symbol after the end of reception of the DRX command MAC CE (or SL-DRX command). 3> The UE can then use a short SL-DRX cycle (Note: Therefore, the UE may transition into an SL-DRX off period) 2>Or 3> Use a long SL-DRX cycle (Note: Therefore, the UE may be in an SL-DRX off-period) 1> When SL-drx-ShortCycleTimer ends 2> Use a long SL-DRX cycle (Note: Therefore, the UE may still move into an SL-DRX off-period) 1> When a long SL-DRX command (long DRX command MAC CE) is received 2> Stop the SL-DRX-ShortCycleTimer 2> Use a long SL-DRX cycle (Note: This may cause the UE to transition into SL-DRX off periods).

[0131] In some implementations, considering again SL-drx-ShortCycle and SL-drx-ShortCycleTimer, when the UE stays in the SL-DRX off period, the following behaviors / mechanisms may be rendered: 1> Use a short SL-DRX cycle, if [(SFN × 10) + subframe number] modulo (SL-drx-ShortCycle) = (SL-drx-StartOffset) modulo (SL-drx-ShortCycle), or 1> If a long SL-DRX cycle is used and [(SFN x 10) + subframe number] modulo (SL-drx-LongCycle) = SL-drx-StartOffset 2>Start SL-drx-onDurationTimer after SL-drx-SlotOffset from the beginning of the subframe (Note: Therefore, the UE may transition to SL-DRX on period).

[0132] Furthermore, in some implementations, the UE may be "awake" on the (LTE / NR) PC5 interface and the (LTE / NR) Uu interface simultaneously (e.g., the UE may follow the C-DRX mechanism to determine whether to wake up on both the Uu interface and the PC5 interface). Furthermore, in some implementations, the UE may maintain the (LTE / NR) PC5 interface in (SL-DRX) active time during the (SL-DRX) active time on the associated (LTE / NR) Uu interface (e.g., when the drx-onDurationTimer or drx-InactivityTimer or drx-RetransmissionTimerDL or drx-RetransmissionTimerUL is running on the associated Uu interface). Thus, under certain conditions, the UE may: Start SL-drx-onDurationTimer when drx-onDurationTimer is started (or vice versa) When the drx-InactivityTimer is started, it starts the SL-drx-InactivityTimer (or vice versa).

[0133] In addition, in some implementations, the UE may simultaneously switch / transition to the C-DRX off period and the SL-DRX off period on not only the Uu interface but also the PC5 interface (e.g., the UE may decide whether to jointly transition to the C-DRX / SL-DRX off period on both the Uu interface and the PC5 interface according to the C-DRX mechanism).

[0134] The UE behavior regarding the implementation of the SL-DRX mechanism is discussed in the above implementations. In some implementations, the UE may send an indicator to the serving cell (e.g., through UE Assistant Information transmission or through a UE Capability Enquiry procedure over the (LTE / NR) Uu interface) to indicate that the UE supports the SL-DRX mechanism or that the UE does not support the SL-DRX mechanism (in some implementations, the default setting is that the UE supports (does not support) the SL-DRX mechanism). Furthermore, the UE's capability regarding SL-DRX support may be stored in the UE AS(Inactive) context on the UE side and the RAN side. In certain UE mobility events (e.g., (inter-RAT, intra-RAT, or inter-system) handover procedures, MCG / SCG addition / modification, RAN notification area update), the UE capability of SL-DRX support may be sent as part of the UE AS(Inactive) context in an inter-node message (e.g., over the Xn interface or X2 interface in the backhaul connection). In some implementations, the UE may also report its ability to support (or not support) SL-DRX to other UE(s) via one or more PC5 interfaces (e.g., PC5-RRC signaling), and this is not intended to limit the scope of the implementation.

[0135] 6 is a diagram illustrating an SL packet exchange procedure 60 performed by a first UE according to an exemplary implementation of the present disclosure. As shown in FIG. 6, the SL packet exchange procedure 60 of the first UE includes the following actions: Action 600: Start Action 602: The first UE may receive an SL-DRX configuration indicating SL-DRX capability. Action 604: The first UE may determine whether to monitor at least one of the first SCI on the PSCCH, the SL packet on the PSSCH, and the second SCI on the PSSCH according to the switching of the SL-DRX active time and the SL-DRX off period. Action 606: End.

[0136] Preferably, actions 602 and 604 of the SL packet exchange procedure 60 may be configured in a first UE. Specifically, in some implementations, the first UE may receive an SL-DRX configuration indicating SL-DRX capability in action 602. Then, in operation 604, the first UE may determine whether to monitor at least one of a first SCI (also referred to as a first stage SCI) on a PSCCH, an SL packet on a next PSSCH, and a second SCI (also referred to as a second stage SCI) on a next PSSCH according to switching between an SL-DRX active time (or an SL-DRX on period) and an SL-DRX off period. Here, the SCI may be from at least one second UE. Both the SL-DRX active time (or the SL-DRX on period) and the SL-DRX off period may be determined by the SL-DRX capability, and the SL transmission may be transmitted over a PC5 interface controlled by NR technology or LTE technology. In some implementations, a first UE may be associated with a second UE in one of an SL unicast group, an SL groupcast group, and an SL broadcast group, In some implementations, the SL unicast group, the SL groupcast group, or the SL broadcast group may be in-coverage with at least one serving cell in the serving RAN, partially in-coverage with at least one cell in the serving RAN, or out-of-coverage of the serving RAN.

[0137] In some implementations, the SL packet exchange procedure 60 may further configure the first UE to determine whether to transmit at least one of a first SCI (or first stage SCI) on a PSCCH and a second SCI (or second stage SCI) / SL packet on a subsequent PSSCH in accordance with a switch between an SL-DRX active time (or an SL-DRX on period) and an SL-DRX off period. In some implementations, the SL packet exchange procedure 60 may be further configured to determine whether to transmit at least one SL-BSR to the first serving cell for an SL resource request or monitor at least one DCI from a second serving cell for SL resource configuration in accordance with a switch between an SL-DRX active time (or an SL-DRX on period) and an SL-DRX off period by the first UE. Here, the first serving cell may be an NR cell of an NR Uu interface or an E-UTRA cell of an E-UTRA Uu interface. In some implementations, the SL packet exchange procedure 60 can further configure the first UE to determine whether to trigger at least one of an SL-SR procedure, an SL-BSR procedure, and an SL-PHR procedure for at least one second UE on the PC5 interface according to switching between the SL-DRX active time (or SL-DRX on period) and the SL-DRX off period.

[0138] In some implementations, the first UE may be configured with different SL resource pool configurations during SL-DRX on periods, SL-DRX active times, or SL-DRX off periods for SL packet exchange operations with at least one second UE, and the SL resource pool configurations may include an SL transmit resource pool configuration, an SL receive resource pool configuration, an exception resource pool configuration, an SL resource pool configuration for SL discovery message transmission, an SL dynamic grant (i.e., one or more SL dynamic grants), a Type-1 SL configured grant (i.e., one or more Type-1 SL configured grants), a Type-2 SL configured grant (i.e., one or more Type-2 SL configured grants), and an SL synchronization signal burst set (i.e., one or more SL synchronization signal burst sets), and the SL resource pool configurations may be between the NR PC5 interface and the E-UTRA PC5 interface. In some implementations, the first UE switches between the SL-DRX active time (or SL-DRX on period) and the SL-DRX off period based on at least one of the SL-DRX-onDurationTimer, SL-DRX-SlotOffset, SL-DRX-InactivityTimer, DRX-RetransmissionTimerSL (e.g., including drx-RetransmissionTimerSL_Rx and / or drx-RetransmissionTimerSL_Tx), SL-DRX-LongCycleStartOffset, SL-DRX-ShortCycle, SL-DRX-ShortCycleTimer, and DRX-HARQ-RTT-TimerSL (e.g., drx-HARQ-RTT-TimerSL_Rx and / or drx-HARQ-RTT-TimerSL_Tx).

[0139] In some implementations, the first UE may be configured to receive the SL-DRX configuration through at least one of SL pre-configuration, PC5-RRC signaling of another paired UE, broadcast SI of the serving cell on the Uu interface, and UE-specific DL RRC signaling on the Uu interface. In some implementations, the first UE may be configured to perform CBR measurement and detection mechanisms according to different SL resource pool configurations during the SL-DRX active time (or SL-DRX on period) or the SL-DRX off period. Note that the first UE and the second UE are only depicted as an exemplary implementation to form two different devices / apparatuses exchanging SL packet(s), and the SL packet exchange procedure 60 may be configured in the second UE for all the above operations / mechanisms for exchanging SL packet(s) with the first UE, and this does not limit the scope of the implementation.

[0140] Referring to FIG. 7, FIG. 7 is a block diagram of a node 700 for wireless communication according to one embodiment of the present disclosure. As shown in FIG. 7, the node 700 may include a transceiver 706, a processor 708, a memory 702, one or more presentation components 704, and at least one antenna 710. The node 700 may also include a radio frequency (RF) spectrum band module, a BS communication module, a NW communication module, a system communication management module, input / output (I / O) ports, I / O components, and a power source (not explicitly shown in FIG. 7). Each of these components may be in communication with each other, directly or indirectly, via one or more buses 724. In one implementation, the node 700 may be a UE or BS that performs various functions disclosed herein, for example, with reference to FIG. 6.

[0141] The transceiver 706, having a transmitter 716 (e.g., transmit / transmit circuitry) and a receiver 718 (e.g., receive / receive circuitry), may be configured to transmit and / or receive time and / or frequency resource partitioning information. In one implementation, the transceiver 706 may be configured to transmit in different types of subframes and slots, including, but not limited to, enabled, disabled, and flexibly enabled subframe and slot formats. The transceiver 706 may be configured to receive data and control channels.

[0142] Node 700 may include a variety of computer-readable media. Computer-readable media may be any available media that can be accessed by node 700, including both volatile (and nonvolatile) and removable (and non-removable) media. By way of example, and not limitation, computer-readable media may include computer storage media and communication media. Computer storage media may include both volatile (and nonvolatile) and removable (and non-removable) media implemented according to any method or technology for storing information such as to be computer-readable.

[0143] Computer storage media include RAM, ROM, EEPROM, flash memory (or other memory technology), CD-ROM, digital versatile disks (DVDs) (or other optical disk storage), magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices), etc. Computer storage media does not include propagated data signals. Communication media may typically embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term "modulated data signal" may mean a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media may include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above disclosures should also be included within the scope of computer-readable media.

[0144] The memory 702 may include computer storage media in the form of volatile and / or nonvolatile memory. The memory 702 may be removable, non-removable, or a combination thereof. For example, the memory 702 may include solid-state memory, a hard drive, an optical disk drive, etc. As shown in FIG. 7, the memory 702 may store computer-executable (or readable) programs 714 (e.g., software code) that, when executed, are configured to cause the processor 708 to perform various functions disclosed herein, e.g., with reference to FIG. 6. Alternatively, the computer-executable programs 714 may not be directly executable by the processor 708, but may be configured (e.g., when compiled and executed) to cause the node 700 to perform various functions disclosed herein.

[0145] The processor 708 (e.g., having processing circuitry) may include an intelligent hardware device, a central processing unit (CPU), a microcontroller, an ASIC, etc. The processor 708 may include memory. The processor 708 may process data 712 and computer-executable programs 714 received from the memory 702, as well as information via the transceiver 706, the baseband communication module, and / or the NW communication module. The processor 708 may also process information for transmission to the transceiver 706 for transmission via the antenna 710 and to the NW communication module for transmission to the CN.

[0146] One or more presentation components 704 may present a data display to a person or other device. Examples of presentation components 704 may include a display device, a speaker, a printing component, a vibrating component, etc.

[0147] According to a first aspect of the present disclosure, there is provided a method performed by a first user equipment (UE) for sidelink (SL) packet-switched operation, the method including: receiving at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the first UE; when an SL-DRX operation is performed based on the at least one SL-DRX configuration, performing partial detection based on at least one of the plurality of SL resource pool configurations, wherein each of the at least one SL resource pool configured by the at least one of the plurality of SL resource pool configurations includes one or more time slots; and performing SL-Channel Busy Ratio (SL-CBR) measurements associated with each of the at least one SL resource pool during the one or more time slots for which partial detection is performed.

[0149] According to a second aspect of the present disclosure, there is provided a user equipment (UE) in a wireless communication system including a base station (BS) for sidelink (SL) packet switching operation, the UE comprising: one or more non-transitory computer-readable media having computer-executable instructions thereon; and at least one processor coupled to the one or more non-transitory computer-readable media, the at least one processor configured to execute the computer-executable instructions to cause the UE to: receive at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the UE; perform partial detection based on at least one of the plurality of SL resource pool configurations when SL-DRX operation is performed based on the at least one SL-DRX configuration, wherein each of the at least one SL resource pool configured by the at least one of the plurality of SL resource pool configurations includes one or more time slots; and perform SL-Channel Busy Ratio (SL-CBR) measurements associated with each of the at least one SL resource pool during the one or more time slots for which partial detection is performed.

[0151] From the foregoing disclosure, it has become apparent that various techniques may be used to implement the concepts described in this disclosure without departing from the scope of those concepts. Moreover, while the concepts have been disclosed with specific reference to particular implementations, those skilled in the art will recognize that changes may be made in form and detail without departing from the scope of those concepts. The disclosed embodiments are thus considered in all respects to be illustrative and not restrictive. It is also to be understood that the disclosure is not limited to the particular disclosed embodiments. Nevertheless, many rearrangements, modifications, and substitutions are possible without departing from the scope of the disclosure. [Brief explanation of the drawings]

[0152] [Figure 1]FIG. 10 illustrates SL operations for UEs to exchange information according to an exemplary embodiment of the present disclosure. [Figure 2] FIG. 1 illustrates a V2X platoon scenario in accordance with an exemplary implementation of the present disclosure. [Figure 3] FIG. 1 illustrates a PC5-RRC connection between a pair of UEs in accordance with an example implementation of the present disclosure. [Figure 4] FIG. 1 illustrates a SL-DRX configuration according to an exemplary implementation of the present disclosure. [Figure 5] 1(a), (b), and (c) illustrate different sidelink (SL) sensing windows according to different exemplary implementations of the present disclosure. [Figure 6] FIG. 10 illustrates an SL packet exchange procedure performed by a first UE in accordance with an example implementation of the present disclosure. [Figure 7] FIG. 1 is a block diagram of a node for wireless communication in accordance with an example implementation of the present disclosure.

Claims

1. 1. A method performed by a first user equipment (UE) for sidelink (SL) packet switched operation, the method comprising: receiving at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the first UE; When an SL-DRX operation is performed based on the at least one SL-DRX configuration, performing partial detection based on at least one of the plurality of SL resource pool configurations, wherein each of at least one SL resource pool configured by the at least one of the plurality of SL resource pool configurations includes one or more time slots; performing a SL-Channel Busy Ratio (SL-CBR) measurement associated with each of the at least one SL resource pool during the one or more time slots during which the partial sensing is performed; receiving an indicator, and determining, based on the indicator, whether the first UE will perform the partial sensing on a first SL resource pool configured by a first SL resource pool configuration during at least one SL-DRX off period.

2. If the first UE determines to perform the partial sensing, performing the partial sensing on the first SL resource pool in the at least one SL-DRX off period; The method of claim 1 , wherein the at least one SL-DRX off period is determined based on a period during which the first UE is not in an SL-DRX active time.

3. 3. The method of claim 2, further comprising: switching the SL-DRX active time and the at least one SL-DRX off period according to at least one of SL-DRX-onDurationTimer, SL-DRX-SlotOffset, SL-DRX-InactivityTimer, DRX-RetransmissionTimerSL, SL-DRX-LongCycleStartOffset, SL-DRX-ShortCycle, SL-DRX-ShortCycleTimer, or DRX-HARQ-RTTTimerSL.

4. If the first UE determines not to perform the partial sensing, disabling performing the partial sensing on the first SL resource pool in the at least one SL-DRX off period; The method of claim 1 , wherein the at least one SL-DRX off period is determined based on a period during which the first UE is not in an SL-DRX active time.

5. The method of claim 1 , wherein the first SL resource pool configuration comprises one of an SL normal transmission resource pool configuration or an SL exception resource pool configuration.

6. The method of claim 1 , further comprising receiving the plurality of SL resource pool configurations from one or more cells operating on one or more SL frequency carriers.

7. performing the partial detection based on at least one of the plurality of SL resource pool configurations, monitoring at least one of a first sidelink control information (SCI) on a physical sidelink control channel (PSCCH), a sidelink control packet on a physical sidelink shared channel (PSSCH), or a second SCI on the PSSCH; the PSCCH and the PSSCH are associated with one SL resource pool of the at least one SL resource pool; The method of claim 1 , wherein the first SCI and the second SCI are from at least one second UE.

8. The plurality of SL resource pool configurations include: SL resource pool configuration for Long Term Evolution Vehicle-to-Everything (LTE-V2X) SL communication services; SL resource pool configuration for LTE-V2X SL discovery service; NR SL: SL resource pool configuration for communication services; SL resource pool configuration for NR SL discovery service; SL resource pool configuration for ProSe discovery service, or SL resource pool configuration for ProSe communication services; The method of claim 1 , comprising at least one of:

9. 1. A user equipment (UE) in a wireless communication system for sidelink (SL) packet switched operation, comprising: The wireless communication system includes a base station (BS), and the UE includes: one or more non-transitory computer-readable media having computer-executable instructions; and at least one processor coupled to the one or more non-transitory computer-readable media, executing the computer-executable instructions to: receiving at least one SL-Discontinuous Reception (SL-DRX) configuration and a plurality of SL resource pool configurations to be configured for the UE; When an SL-DRX operation is performed based on the at least one SL-DRX configuration, performing partial detection based on at least one of the plurality of SL resource pool configurations, wherein each of at least one SL resource pool configured by the at least one of the plurality of SL resource pool configurations includes one or more time slots; performing a SL-Channel Busy Ratio (SL-CBR) measurement associated with each of the at least one SL resource pool during the one or more time slots during which the partial sensing is performed; and at least one processor configured to cause the UE to perform the following steps: receive an indicator; and determine, based on the indicator, whether the UE will perform the partial sensing on a first SL resource pool configured by a first SL resource pool configuration during at least one SL-DRX off period.

10. The at least one processor and further configured to execute the computer-executable instructions causing the UE to perform the partial sensing on the first SL resource pool in the at least one SL-DRX off period if the UE determines to perform the partial sensing; The UE of claim 9 , wherein the at least one SL-DRX off period is determined based on a period during which the UE is not in an SL-DRX active time.

11. The at least one processor 11. The UE of claim 10, further configured to execute the computer-executable instructions to cause the UE to perform the step of switching between the SL-DRX active time and the at least one SL-DRX off period according to at least one of SL-DRX-onDurationTimer, SL-DRX-SlotOffset, SL-DRX-InactivityTimer, DRX-RetransmissionTimerSL, SL-DRX-LongCycleStartOffset, SL-DRX-ShortCycle, SL-DRX-ShortCycleTimer, or DRX-HARQ-RTTTimerSL.

12. The at least one processor and further configured to execute the computer-executable instructions to cause the UE to perform a step of disabling performing the partial detection on the first SL resource pool in the at least one SL-DRX off period if the UE determines not to perform the partial detection; The UE of claim 9 , wherein the at least one SL-DRX off period is determined based on a period during which the UE is not in an SL-DRX active time.

13. The UE of claim 9 , wherein the first SL resource pool configuration comprises one of an SL normal transmission resource pool configuration or an SL exception resource pool configuration.

14. The at least one processor 10. The UE of claim 9, configured to execute the computer-executable instructions to cause the UE to perform the step of receiving the plurality of SL resource pool configurations from one or more cells operating on one or more SL frequency carriers.

15. performing the partial detection based on at least one of the plurality of SL resource pool configurations, monitoring at least one of a first sidelink control information (SCI) on a physical sidelink control channel (PSCCH), a sidelink control packet on a physical sidelink shared channel (PSSCH), or a second SCI on the PSSCH; The PSCCH and the PSSCH are Associated with one SL resource pool, The first SCI and the second SCI are from at least one second UE. The UE of claim 9,

16. The plurality of SL resource pool configurations include: Long-Term Evolution Vehicle-to-Everything (LT SL resource pool configuration for E-V2X) SL communication services, SL resource pool configuration for LTE-V2X SL discovery service; NR SL: SL resource pool configuration for communication services; SL resource pool configuration for NR SL discovery service; SL resource pool configuration for ProSe discovery service, or SL resource pool configuration for ProSe communication services; The UE of claim 9, comprising at least one of:

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