Patent Publication Number: US-2022224497-A1

Title: Method and apparatus of handling discontinuous reception and partial sensing for sidelink communication in a wireless communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 63/137,103, filed Jan. 13, 2021, which is fully incorporated herein by reference. 
    
    
     FIELD 
     This disclosure generally relates to wireless communication networks and, more particularly, to a method and apparatus for handling discontinuous reception and partial sensing for sidelink communication. 
     BACKGROUND 
     With the rapid rise in demand for communication of large amounts of data to and from mobile communication devices, traditional mobile voice communication networks are evolving into networks that communicate with Internet Protocol (IP) data packets. Such IP data packet communication can provide users of mobile communication devices with voice over IP, multimedia, multicast and on-demand communication services. 
     An exemplary network structure is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system can provide high data throughput in order to realize the above-noted voice over IP and multimedia services. A new radio technology for the next generation (e.g., 5G) is currently being discussed by the 3GPP standards organization. Accordingly, changes to the current body of 3GPP standard are currently being submitted and considered to evolve and finalize the 3GPP standard. 
     SUMMARY 
     Methods and apparatuses are provided for handling discontinuous reception and partial sensing for sidelink communication to reduce potential latency due to additional sensing, and to improve resource utilization efficiency. 
     In one embodiment, a method of a first device performs sidelink communication to at least a second device in a sidelink resource pool and comprises the steps where the first device triggers to perform resource selection for a sidelink data, at a timing. The first device performs sensing for a first contiguous sensing duration before a sidelink on-duration active time of the second device. The first device determines/selects a first sidelink resource from a set of sidelink resources, wherein the set of sidelink resources is derived or determined based on at least sensing result in the first contiguous sensing duration. The first device performs a first sidelink transmission on the first sidelink resource for transmitting the sidelink data to the second device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagram of a wireless communication system, in accordance with embodiments of the present invention. 
         FIG. 2  is a block diagram of a transmitter system (also known as access network) and a receiver system (also known as user equipment or UE), in accordance with embodiments of the present invention. 
         FIG. 3  is a functional block diagram of a communication system, in accordance with embodiments of the present invention. 
         FIG. 4  is a functional block diagram of the program code of  FIG. 3 , in accordance with embodiments of the present invention. 
         FIG. 5  is a reproduction of FIG. 4 of R1-2007615, showing that an aperiodic reservation (indicated in SCI) cannot be monitored. 
         FIG. 6  is a reproduction of FIG. 5 of R1-2007615, showing an extended partial sensing window for aperiodic traffic. 
         FIG. 7  is a reproduction of FIG. 4 of R1-2007688, showing an additional sensing window: short term partial sensing window. 
         FIG. 8  is a reproduction of FIG. 1 of R1-2008189, showing partial sensing for intra- and cross-period reservations. 
         FIG. 9  is a reproduction of FIGS. 1 and 2 of R1-2009072, with FIG. 1 showing partial sensing following LTE behavior and FIG. 2 showing partial sensing for NR (considering aperiodic nature of traffic). 
         FIG. 10  is a reproduction of FIG. 2 of R1-2009272, showing performing random selection with subsequent revaluation. 
         FIG. 11  is a reproduction of FIG. 3 of R1-2009272, showing performing sensing after resource selection trigger. 
         FIG. 12  shows a UE having a candidate resource set comprising multiple candidate resources, in accordance with embodiments of the present invention. 
         FIG. 13  shows a possible way for a UE to acquire sensing results in the sidelink non-active time by performing partial sensing in sidelink active time, in accordance with embodiments of the present invention. 
         FIGS. 14A-14B  shows a UE triggering resource sensing (and selection), e.g., in slot n, for a sidelink data, (starting to) perform additional sensing for an additional sensing duration, e.g., in a time interval, in accordance with embodiments of the present invention. 
         FIG. 15A  shows a case where the first UE may trigger resource sensing and selection in slot  220 , in accordance with embodiments of the present invention. 
         FIG. 15B  shows a case where the first UE may trigger resource sensing and selection in slot  210 , while the first UE does not perform additional sensing in slot [ 210 ,  219 ], in accordance with embodiments of the present invention. 
         FIG. 15C  shows a case where the first UE may start to perform additional sensing when the first UE triggers to perform the resource sensing and selection, in accordance with embodiments of the present invention. 
         FIG. 15D  shows a case where the set of contiguous slots is the specific value of contiguous slots, in accordance with embodiments of the present invention. 
         FIG. 16  is a flow diagram of a method of a first device performing sidelink communication to at least a second device, in accordance with embodiments of the present invention. 
         FIG. 17  is a flow diagram of a method of a first device performing sidelink communication to at least a second device in a sidelink resource pool, in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The invention described herein can be applied to or implemented in exemplary wireless communication systems and devices described below. In addition, the invention is described mainly in the context of the 3GPP architecture reference model. However, it is understood that with the disclosed information, one skilled in the art could easily adapt for use and implement aspects of the invention in a 3GPP2 network architecture as well as in other network architectures. 
     The exemplary wireless communication systems and devices described below employ a wireless communication system, supporting a broadcast service. Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), 3GPP LTE (Long Term Evolution) wireless access, 3GPP LTE-A (Long Term Evolution Advanced) wireless access, 3GPP2 UMB (Ultra Mobile Broadband), WiMax, 3GPP NR (New Radio), or some other modulation techniques. 
     In particular, the exemplary wireless communication systems and devices described below may be designed to support one or more standards such as the standard offered by a consortium named “3rd Generation Partnership Project” referred to herein as 3GPP, including: [1] 3GPP TS 36.213 V16.4.0 (2020-12), “3GPP TSG RAN; E-UTRA Physical layer procedures (Release 16)”; [2] 3GPP TS 38.214 V16.4.0 (2020-12), “3GPP TSG RAN; NR Physical layer procedures for data (Release 16)”; [3] 3GPP TS 38.213 V16.4.0 (2020-12), “3GPP TSG RAN; NR Physical layer procedures for control (Release 16)”; [4] 3GPP TS 38.212 V16.4.0 (2020-12), “3GPP TSG RAN; NR Multiplexing and channel coding (Release 16)”; [5] 3GPP TS 38.321 V16.3.0 (2020-12), “3GPP TSG RAN; NR Medium Access Control (MAC) protocol specification (Release 16)”; [6] RP-202846, “WID revision: NR sidelink enhancement”; [7] Draft Report of 3GPP TSG RAN WG1 #103-e v0.2.0 (Online meeting, 26 Oct.-13 Nov. 2020); [8] R2-2100001, “Report of 3GPP TSG RAN2 #112-e meeting, Online”; [9] R1-2007615, “Sidelink resource allocation to reduce power consumption”, Huawei, HiSilicon; [10] R1-2007688, “Resource allocation for sidelink power saving”, vivo; [11] R1-2008189, “On Resource Allocation for Power Saving”, Samsung; [12] R1-2009072, “Resource allocation mechanisms for power saving”, Ericsson; and [13] R1-2009272, “Power Savings for Sidelink”, Qualcomm Incorporated. The standards and documents listed above are hereby expressly and fully incorporated herein by reference in their entirety. 
       FIG. 1  shows a multiple access wireless communication system according to one embodiment of the invention. An access network  100  (AN) includes multiple antenna groups, one including  104  and  106 , another including  108  and  110 , and an additional including  112  and  114 . In  FIG. 1 , only two antennas are shown for each antenna group, however, more or fewer antennas may be utilized for each antenna group. Access terminal (AT)  116  is in communication with antennas  112  and  114 , where antennas  112  and  114  transmit information to access terminal  116  over forward link  120  and receive information from AT  116  over reverse link  118 . AT  122  is in communication with antennas  106  and  108 , where antennas  106  and  108  transmit information to AT  122  over forward link  126  and receive information from AT  122  over reverse link  124 . In a FDD system, communication links  118 ,  120 ,  124  and  126  may use different frequency for communication. For example, forward link  120  may use a different frequency than that used by reverse link  118 . 
     Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access network. In the embodiment, antenna groups each are designed to communicate to access terminals in a sector of the areas covered by access network  100 . 
     In communication over forward links  120  and  126 , the transmitting antennas of access network  100  may utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals  116  and  122 . Also, an access network using beamforming to transmit to access terminals scattered randomly through its coverage normally causes less interference to access terminals in neighboring cells than an access network transmitting through a single antenna to all its access terminals. 
     The AN may be a fixed station or base station used for communicating with the terminals and may also be referred to as an access point, a Node B, a base station, an enhanced base station, an eNodeB, or some other terminology. The AT may also be called User Equipment (UE), a wireless communication device, terminal, access terminal or some other terminology. 
       FIG. 2  is a simplified block diagram of an embodiment of a transmitter system  210  (also known as the access network) and a receiver system  250  (also known as access terminal (AT) or user equipment (UE)) in a MIMO system  200 . At the transmitter system  210 , traffic data for a number of data streams is provided from a data source  212  to a transmit (TX) data processor  214 . 
     In one embodiment, each data stream is transmitted over a respective transmit antenna. TX data processor  214  formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. 
     The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor  230 . 
     The modulation symbols for all data streams are then provided to a TX MIMO processor  220 , which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor  220  then provides N T  modulation symbol streams to N T  transmitters (TMTR)  222   a  through  222   t . In certain embodiments, TX MIMO processor  220  applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted. 
     Each transmitter  222  receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. N T  modulated signals from transmitters  222   a  through  222   t  are then transmitted from N T  antennas  224   a  through  224   t , respectively. 
     At receiver system  250 , the transmitted modulated signals are received by N R  antennas  252   a  through  252   r  and the received signal from each antenna  252  is provided to a respective receiver (RCVR)  254   a  through  254   r . Each receiver  254  conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream. 
     An RX data processor  260  then receives and processes the N R  received symbol streams from N R  receivers  254  based on a particular receiver processing technique to provide N T  “detected” symbol streams. The RX data processor  260  then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor  260  is complementary to that performed by TX MIMO processor  220  and TX data processor  214  at transmitter system  210 . 
     A processor  270  periodically determines which pre-coding matrix to use (discussed below). Processor  270  formulates a reverse link message comprising a matrix index portion and a rank value portion. 
     The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor  238 , which also receives traffic data for a number of data streams from a data source  236 , modulated by a modulator  280 , conditioned by transmitters  254   a  through  254   r , and transmitted back to transmitter system  210 . 
     At transmitter system  210 , the modulated signals from receiver system  250  are received by antennas  224 , conditioned by receivers  222 , demodulated by a demodulator  240 , and processed by a RX data processor  242  to extract the reserve link message transmitted by the receiver system  250 . Processor  230  then determines which pre-coding matrix to use for determining the beamforming weights then processes the extracted message. 
     Memory  232  may be used to temporarily store some buffered/computational data from  240  or  242  through Processor  230 , store some buffed data from  212 , or store some specific program codes. And Memory  272  may be used to temporarily store some buffered/computational data from  260  through Processor  270 , store some buffed data from  236 , or store some specific program codes. 
     Turning to  FIG. 3 , this figure shows an alternative simplified functional block diagram of a communication device according to one embodiment of the invention. As shown in  FIG. 3 , the communication device  300  in a wireless communication system can be utilized for realizing the UEs (or ATs)  116  and  122  in  FIG. 1 , and the wireless communications system is preferably the NR system. The communication device  300  may include an input device  302 , an output device  304 , a control circuit  306 , a central processing unit (CPU)  308 , a memory  310 , a program code  312 , and a transceiver  314 . The control circuit  306  executes the program code  312  in the memory  310  through the CPU  308 , thereby controlling an operation of the communications device  300 . The communications device  300  can receive signals input by a user through the input device  302 , such as a keyboard or keypad, and can output images and sounds through the output device  304 , such as a monitor or speakers. The transceiver  314  is used to receive and transmit wireless signals, delivering received signals to the control circuit  306 , and outputting signals generated by the control circuit  306  wirelessly. 
       FIG. 4  is a simplified block diagram of the program code  312  shown in  FIG. 3  in accordance with an embodiment of the invention. In this embodiment, the program code  312  includes an application layer  400 , a Layer  3  portion  402 , and a Layer  2  portion  404 , and is coupled to a Layer  1  portion  406 . The Layer  3  portion  402  generally performs radio resource control. The Layer  2  portion  404  generally performs link control. The Layer  1  portion  406  generally performs physical connections. 
     For LTE, LTE-A, or NR systems, the Layer  2  portion  404  may include a Radio Link Control (RLC) layer and a Medium Access Control (MAC) layer. The Layer  3  portion  402  may include a Radio Resource Control (RRC) layer. 
     Any two or more than two of the following paragraphs, (sub-)bullets, points, actions, or claims described in each invention may be combined logically, reasonably, and properly to form a specific method. 
     Any sentence, paragraph, (sub-)bullet, point, action, or claim described in each of the following invention may be implemented independently and separately to form a specific method. Dependency, e.g., “based on”, “more specifically”, etc., in the following invention is just one possible embodiment which would not restrict the specific method. 
     TS 36.213[1] specifies physical sidelink shared channel related procedures in LTE. For acquiring sidelink resources, it specifies (periodic-based) partial sensing for sidelink transmission mode 4. 

 
     Some or all of the following terminology and assumptions may be used herein.
         BS: a network central unit or a network node in NR which is used to control one or multiple TRPs which are associated with one or multiple cells. Communication between BS and TRP(s) is via fronthaul. BS may be referred to as central unit (CU), eNB, gNB, or NodeB.   TRP: a transmission and reception point provides network coverage and directly communicates with UEs. TRP may be referred to as distributed unit (DU) or network node.   Cell: a cell is composed of one or multiple associated TRPs, i.e. coverage of the cell is composed of coverage of all associated TRP(s). One cell is controlled by one BS. Cell may be referred to as TRP group (TRPG).   Slot: a scheduling unit in NR. Slot duration is 14 OFDM symbols.
 
For the network side:
   Downlink timing of TRPs in the same cell are synchronized.   RRC layer of network side is in BS.
 
For the UE side:
   There are at least two UE (RRC) states: connected state (or called active state) and non-connected state (or called inactive state or idle state). Inactive state may be an additional state or belong to connected state or non-connected state.       

     Issues and Solutions: 
     In LTE/LTE-A sidelink (see e.g., TS 36.213 V16.4.0), sensing-based resource selection procedures are supported in sidelink transmission mode 4. As an instance shown in  FIG. 12 , a User Equipment (UE) has a candidate resource set comprising multiple candidate resources. The available candidate resource set is restricted with time interval [n+T 1 ,n+T 2 ], which may be called as resource selection window. When (periodic-based) partial sensing is configured, the UE determines, by its implementation, a set of subframes which consists of at least Y subframes within the time interval [n+T 1 ,n+T 2 ], wherein the available candidate resource set are in the set of subframes. If full sensing is performed, e.g., partially sensing is not configured, the available candidate resource set are in the (full) time interval [n+T 1 ,n+T 2 ]. Preferably, a candidate resource may mean one candidate single-subframe resource. One candidate resource may comprise one or multiple resource units. The resource unit may be a sub-channel Preferably, the resource unit may comprise multiple (physical) resource blocks in a Transmission Time Interval (TTI). The TTI may be a subframe in LTE. 
     Based on the sensing result within a sensing duration, the UE may generate a valid/identified resource set, wherein the valid/identified resource set is a subset of the candidate resource set. The generation of the valid/identified resource set may be performed via excluding some candidate resources from the candidate resource set—for instance, step  2 - 1  and step  2 - 2  shown in  FIG. 12 . The generation of the valid/identified resource set may be performed via selecting some valid/identified candidate resources—for instance, step  3 - 1  shown in  FIG. 12 . And then, the UE selects one or some valid/identified resources from the valid/identified resource set to perform sidelink transmission from the UE. The resource selection for sidelink transmission may be randomly selected from the valid/identified resource set—for instance, step  3 - 2  shown in  FIG. 12 . 
     As in TS 36.213 V16.4.0, the first excluding step is that if the UE does not monitor/sense a TTI z, the UE cannot expect whether the candidate resources in TTI “z+P any ” are occupied or not, wherein P any  means any possible periodicity for transmission. For instance, the first excluding step is shown as step  2 - 1  in  FIG. 12 . For the case of P any &gt;=100 ms, the UE excludes the candidate resources in TTI “z+P any ” and excludes the candidate resources for which the UE may have possible transmission occurred in TTI “z+P any ”. For the case of P any &lt;100 ms, the UE excludes the candidate resources in TTI “z+q·P any ” and excludes the candidate resources for which the UE may have possible transmission occurred in TTI “z+q·P any ”, wherein q is 1, 2, . . . , 100/P any . The parameter q means that the UE excludes multiple candidate resources with period P any  within time interval [z, z+100]. The possible transmission may mean a transmission on a selected resource. The possible transmission may mean a periodic transmission of a transmission on a selected resource. Moreover, P any  means any possible periodicity configured by higher layer. 
     The second excluding step is that if the UE receives/detects a control signaling in a TTI m, the UE may exclude the candidate resources according to the received control signaling. For instance, the second excluding step is shown as step  2 - 2  in  FIG. 12 . More specifically, if the UE receives/detects a control signaling scheduling a transmission in a TTI m and the measurement result of the scheduled transmission and/or the control signal is over a threshold, the UE may exclude the candidate resources according to the received control signaling. The measurement result may be Reference Signal Received Power (RSRP). More specifically, the measurement result may be Physical Sidelink Shared Channel (PSSCH)-RSRP. The control signaling may indicate the resources of the scheduled transmission and/or periodicity of the scheduled transmission, P RX . The excluded candidate resources according to the received control signaling are the resources of next one scheduled transmission based on the resources of the scheduled transmission and periodicity of the scheduled transmission, such as for the case of P RX &gt;=100 ms. Moreover, the excluded candidate resources according to the received control signaling are the resources of next multiple scheduled transmissions based on the resources of the scheduled transmission and periodicity of the scheduled transmission, such as for the case of P RX &lt;100 ms. The next multiple scheduled transmissions may be with period P RX  within time interval [m, m+100]. If the control signaling indicates that there is no next scheduled transmission, or the control signaling indicates that the resource of scheduled transmission is not kept in next time, or the control signaling indicates that the scheduled transmission is the last transmission from the UE transmitting the control signaling, or the control signaling indicates that the periodicity of the scheduled transmission is indicated as zero, the UE may not exclude candidate resources according to the received control signaling. 
     After the first excluding step and the second excluding step, the UE may select some valid/identified candidate resources from the remaining candidate resources, such as shown in step  3 —of  FIG. 12 . The UE may measure resources in the sensing duration, wherein the measured resources are associated with the remaining candidate resources after step  2 - 1  and step  2 - 2 . More specifically, for a remaining candidate resource, the associated measured resources in the sensing duration are in the occasions with multiple times of a time period from the remaining candidate resources. For instance, if the time period is 100 TTIs, the associated measured resources in the sensing duration are in the TTI “n−j·100”, where j is a positive integer, for a remaining candidate resource in TTI n. Moreover, the associated measured resources in the sensing duration are with the same frequency resources as the remaining candidate resource. More specifically, the measurement is S-Received Signal Strength Indicator (S-RSSI) measurement. 
     Based on the measurement, the UE can derive metric for each remaining candidate resource. The metric for a remaining candidate resource may be linear average of S-RSSI measured from its associated measured resources in the sensing duration. And then, the UE may select valid/identified candidate resources based on the metric of each remaining candidate resource. Preferably, an action is that a remaining candidate resource with the smallest metric is selected as valid/identified candidate resource and moved into a valid/identified resource set. Repeating the action until the UE selects a number of remaining candidate resources as valid candidate resources and moves the number of remaining candidate resources into the valid/identified resource set. For instance, the number is larger than or equal to 20% of total candidate resources. The number is larger than or equal to 20% of cardinality of the candidate resource set. 
     Based on the current (partially) sensing procedures, the UE can determine the valid/identified resource set. The valid/identified resource set may be reported to higher layers for sidelink transmission from the UE. The UE may select one or some valid/identified resources from the valid/identified resource set to perform sidelink transmission from the UE. The sidelink transmission from the UE may be PSSCH transmission. Preferably, the sidelink transmission from the UE may be device-to-device transmission. 
     For NR sidelink transmission, there are two sidelink resource allocation modes defined for NR-Vehicle-to-Everything (V2X) sidelink communication (see e.g., TS 38.214 V16.4.0):
         mode 1 is that the base station/network node can schedule sidelink resource(s) to be used by the UE for sidelink transmission(s), which concept is similar as sidelink transmission mode 3 in LTE/LTE-A (see e.g., TS 36.213 V16.4.0).   mode 2 is that the UE determines (e.g., base station/network node does not schedule) sidelink transmission resource(s) within sidelink resources configured by the base station/network node or pre-configured sidelink resources, which concept is similar as sidelink transmission mode 4 in LTE/LTE-A (see e.g., TS 36.213 V16.4.0).       

     For network scheduling mode, e.g., NR sidelink resource allocation mode 1, the network node may transmit a sidelink (SL) grant on Uu interface for scheduling resources of PSCCH and/or PSSCH. The V2X UE may perform PSCCH and PSSCH transmissions on PC5 interface, in response to the received sidelink grant. The Uu interface means the wireless interface for communication between network and UE. The PC5 interface means the wireless interface for communication (directly) between UEs/devices. 
     For UE (autonomous) selection mode, e.g., NR sidelink resource allocation mode 2, since transmission resource is not scheduled via the network, the UE may require performing sensing before selecting a resource for transmission (e.g., sensing-based transmission) in order to avoid resource collision and interference from or to other UEs. Currently, full sensing is supported in NR sidelink. Partial sensing is not supported/designed for NR sidelink. Moreover, step  3 - 1  shown in  FIG. 12  is not applied for sensing procedure in NR sidelink (see e.g., TS 38.214 V16.4.0). Based on the result of the sensing procedure, the UE can determine a valid/identified resource set. The valid/identified resource set may be reported to higher layers (of the UE). The UE may (randomly) select one or multiple valid/identified resources from the valid/identified resource set to perform sidelink transmission(s) from the UE. The sidelink transmission(s) from the UE may be PSCCH and/or PSSCH transmission. 
     In the Justification and objective of work item for NR Rel-17 V2X, power saving is one of enhancement to enable UEs with battery constraint to perform sidelink operations in a power efficient manner. To reduce power consumption, it may specify/design partial sensing to Rel-17 NR sidelink resource allocation mode 2. Thus, a UE may perform partial sensing to select sidelink resources, instead of performing full sensing with more power consumption. Note that the partial sensing and resource selection is performed from the transmitter aspect of the UE. 
     In another aspect, work item for NR Rel-17 V2X may specify/design sidelink Discontinuous Reception (DRX) for a UE to reduce power consumption, since the UE will not need to wake up all the time. It means that the UE will not need to monitor/decode Physical Sidelink Control Channel (PSCCH) and/or PSSCH in all sidelink slots. Preferably, the UE may monitor/decode PSCCH and/or PSSCH in sidelink active time. The UE may not monitor/decode PSCCH and/or PSSCH in sidelink non-active time. The DRX procedure in NR Uu may be considered to apply, with some modification, to NR sidelink. Preferably, if DRX cycle is introduced for sidelink and/or a DRX on-duration timer for sidelink is introduced, the sidelink active time of the UE may include the time while the DRX on-duration timer for sidelink is running Preferably, if a DRX Inactivity timer for sidelink is introduced, the sidelink active time of the UE may include the time while the DRX Inactivity timer for sidelink is running Preferably, if a DRX retransmission timer for sidelink is introduced, the sidelink active time of the UE may include the time while the DRX retransmission timer for sidelink is running Preferably, the sidelink active time of the UE may include the time while any of the DRX on-duration timer for sidelink, the DRX Inactivity timer for sidelink, or the DRX retransmission timer for sidelink is running Note that the sidelink DRX is performed from the receiver aspect of the UE. 
     Although sidelink DRX is able to reduce power consumption for a UE, it may mean that the UE will not monitor/decode PSCCH in sidelink non-active time. Accordingly, the UE will not receive PSCCH or Sidelink Control Information (SCI) from other UE(s) in the sidelink non-active time; thus, the UE cannot acquire sensing results in the sidelink non-active time. 
     One possible way is to perform partial sensing in sidelink active time as provided in the instance shown in  FIG. 13 . When the UE triggers resource sensing (and selection), e.g., in slot n, for a sidelink data, candidate resources in the associated resource selection window can be determined/restricted within sidelink active time. Note that the associated resource selection window, e.g., in time interval [n+T 1 , n+T 2 ], may be upper bounded based on remaining packet delay budget (PDB). 
     Moreover, exclusion of the candidate resources and/or generation of valid/identified resources in the associated resource selection window can be performed based on sensing results in previous one or multiple sidelink active times, e.g., the partial/periodic sensing results as shown in  FIG. 13 . For example, the UE may receive a SCI from other UE in previous sidelink active time, wherein the received SCI reserves one or more sidelink resources located in the associated resource selection window. More specifically, the received SCI may schedule/indicate sidelink transmission from the other UE for delivering/transmitting one Transport Block (TB), and the received SCI may reserve the one or more sidelink resource for another TB different from the one TB. Preferably, the received SCI may schedule/indicate the sidelink transmission for delivering/transmitting the one TB via “Frequency resource assignment” field and “Time resource assignment field”. Preferably, the received SCI may reserve the one or more sidelink resource for the another TB via “Resource reservation period” field and/or “Frequency resource assignment” field and “Time resource assignment field”. In this case, the UE may exclude candidate resource(s) (partially or fully) overlapped with the one or more sidelink resources reserved by the SCI received in previous sidelink active time. The UE may not generate valid/identified resource (partially or fully) overlapped with the one or more sidelink resources reserved by the SCI received in previous sidelink active time. Finally, the UE may select one or more sidelink resource(s) from the valid/identified resources, and then perform sidelink transmission(s) on the selected one or more sidelink resource(s). 
     The instance shown in  FIG. 13  can deal with sensing results associated with resource reservation information of periodic sidelink data (e.g., the one TB and the another TB from the other UE). However, the UE may not acquire resource reservation information of aperiodic sidelink data (transmitted from other UEs). In current NR sidelink design, one SCI in slot m can schedule/indicate sidelink resource(s), for a same TB, up to slot m+31. Thus, there are some proposals (see e.g., [9]-[13]) to perform additional sensing for acquiring such resource reservation information of aperiodic sidelink data. Accordingly, exclusion of the candidate resources and/or generation of valid/identified resources can be performed based on partial/periodic sensing results and the additional sensing result. 
     As shown in the instances of  FIGS. 14A and 14B , when the UE triggers resource sensing (and selection), e.g., in slot n, for a sidelink data, the UE may (start to) perform additional sensing for an additional sensing duration, e.g., in a time interval [n, n+T 4 ] or (n, n+T 4 ], for acquiring resource reservation information from other UEs. More specifically, T 4  may be 31. The associated resource selection window may start after the additional sensing duration, e.g., in time interval [n+T 4 +T 1 , n+T 4 +T 2 ] shown in  FIG. 14A  or in time interval [n+T 4 +T 1 , n+T 2 ] shown in  FIG. 14B . Exclusion of the candidate resources and/or generation of valid/identified resources in the associated resource selection window can be performed based on sensing results in previous one or multiple sidelink active times and sensing results in the additional sensing duration. 
     For example, the UE may receive a SCI from other UE in the additional sensing duration, wherein the received SCI may schedule/indicate sidelink transmission(s) from the other UE in the associated resource selection window. More specifically, the received SCI may schedule/indicate sidelink resource(s) for the scheduled/indicated sidelink transmission(s) from the other UE. Preferably, the received SCI may schedule/indicate the sidelink resource(s) via “Frequency resource assignment” field and “Time resource assignment field”, and/or “Resource reservation period” field. In this case, the UE may exclude candidate resource(s) (partially or fully) overlapped with the sidelink resource(s) scheduled/indicated/reserved by the SCI received in the additional sensing duration. The UE may not generate valid/identified resource (partially or fully) overlapped with the sidelink resource(s) scheduled/indicated/reserved by the SCI received in the additional sensing duration. Finally, the UE may select one or more sidelink resources from the valid/identified resources, and then perform sidelink transmission(s) on the selected one or more sidelink resources. 
     However, the additional sensing design may induce some issues. 
     One issue is that when the UE triggers resource sensing and selection for a sidelink data, the additional sensing duration may induce latency, e.g., additional 31 slots, for delivering/transmitting the sidelink data. This issue is because the UE can select sidelink resource after the additional sensing duration. 
     Moreover, the additional sensing duration may induce restriction such that sidelink resources in the starting 32 slots of each sidelink active time are non-selectable or non-usable for the UE to perform sidelink transmission, since the UE can select sidelink resources after performing additional sensing duration. Such restriction will result in additional latency and inefficiency on resource utilization. 
     To address the referenced problems and issues, various embodiments, methods, systems, devices, and mechanisms are provided below. 
     A first UE may operate sidelink DRX. The first UE may receive/monitor SCI in sidelink active time. The sidelink active time may be determined/derived based on sidelink DRX configuration/parameters. The sidelink active time may occur periodically (e.g., every DRX cycle). The concept of this method b is that the first UE may perform additional sensing, to acquire resource reservation information from one or more other UEs, for a set of (contiguous) slots before starting boundary/timing of one sidelink active time. Preferably in certain embodiments, the number of the set of (contiguous) slots may be equal to a specific value. 
     Preferably in certain embodiments, the set of (contiguous) slots may be/mean a specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. Preferably or alternatively in certain embodiments, the number of the set of (contiguous) slots may be smaller than the specific value. Preferably in certain embodiments, the set of (contiguous) slots may be (latter) part of a specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     For an example of assuming 31 slots are required for additional sensing (e.g., the specific value is 31), if a sidelink active time for the UE is in slot [ 251 ,  320 ] (assume previous sidelink active time is in slot [ 51 ,  120 ]), the UE may perform additional sensing in additional sensing duration [ 220 ,  250 ] or [ 220 ,  251 ). Preferably in certain embodiments, the first UE may trigger resource sensing and selection in slot  220 , as shown in  FIG. 15A . Preferably or alternatively in certain embodiments, the first UE may trigger resource sensing and selection in slot  210 , while the first UE does not perform additional sensing in slot [ 210 ,  219 ], as shown in  FIG. 15B . 
     Preferably in certain embodiments, the specific value may be 31. Preferably or alternatively in certain embodiments, the specific value may be 32. 
     Preferably or alternatively in certain embodiments, the specific value may be (31+T 1 ), or ceiling function of (31+T 1 ). 
     Preferably in certain embodiments, the specific value may be a (pre-)configured value. Preferably in certain embodiments, the specific value may be a specified value. 
     Preferably in certain embodiments, the first UE may perform the sidelink DRX and/or the additional sensing in a sidelink resource pool. Preferably in certain embodiments, the specific value may be determined based on CBR of the sidelink resource pool. For example, the specific value may be determined as a smaller value if CBR of the sidelink resource pool is lower than a CBR threshold. The specific value may be determined as a larger value if CBR of the sidelink resource pool is larger than the CBR threshold. Alternatively, the specific value may be determined as a larger value if CBR of the sidelink resource pool is lower than a CBR threshold. The specific value may be determined as a smaller value if CBR of the sidelink resource pool is larger than the CBR threshold 
     Preferably in certain embodiments, the first UE may (trigger to) perform resource sensing (and selection) for determining a first sidelink resource, and then the first UE performs a first (control and/or data) sidelink transmission on the first sidelink resource for delivering/transmitting a sidelink data. 
     Preferably in certain embodiments, the specific value may be determined based on a data priority of the sidelink data. For example, the specific value may be determined as a smaller value if data priority of the sidelink data is lower than a priority threshold. The specific value may be determined as a larger value if data priority of the sidelink data is higher than the priority threshold. Alternatively, the specific value may be determined as a larger value if data priority of the sidelink data is lower than a priority threshold. The specific value may be determined as a smaller value if data priority of the sidelink data is higher than the priority threshold. 
     Preferably in certain embodiments, the specific value may be determined based on a latency requirement or (remaining) PDB of the sidelink data. For example, the specific value may be determined as a smaller value if latency requirement or (remaining) PDB of the sidelink data is shorter than a time threshold. The specific value may be determined as a larger value if latency requirement or (remaining) PDB of the sidelink data is larger than the time threshold. Alternatively, the specific value may be determined as a larger value if latency requirement or (remaining) PDB of the sidelink data is shorter than a time threshold. The specific value may be determined as a smaller value if latency requirement or (remaining) PDB of the sidelink data is larger than the time threshold. 
     In one embodiment, the first UE may (trigger to) perform the resource sensing (and selection), before starting boundary/timing of the one sidelink active time. Preferably in certain embodiments, the first UE may (trigger to) perform the resource sensing (and selection) in sidelink non-active time. Preferably in certain embodiments, the first sidelink resource is in the one sidelink active time. A sidelink resource in sidelink non-active time may not be allowed to be the first sidelink resource. The first UE prevents/precludes from selecting sidelink resources in sidelink non-active time as the first sidelink resource. 
     Preferably in certain embodiments, the first UE may perform the additional sensing for the set of (contiguous) slots before starting boundary/timing of one sidelink active time, if the first UE (triggers to) performs the resource sensing (and selection) before starting boundary/timing of the one sidelink active time. If the first UE does not (trigger to) perform the resource sensing (and selection) within sidelink non-active time before starting boundary/timing of one sidelink active time, the first UE may not perform the additional sensing for the set of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     Preferably in certain embodiments, if the first UE (triggers to) performs the resource sensing (and selection) in a timing before the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time, the first UE starts to perform additional sensing in the specific value of (contiguous) slots. It may mean that the set of (contiguous) slots is the specific value of (contiguous) slots. Preferably in certain embodiments, the first UE may perform additional sensing for an additional sensing duration, wherein the additional sensing duration comprises/includes/consists of the specific value of (contiguous) slots. Preferably in certain embodiments, the first UE does not perform additional sensing before the specific value of (contiguous) slots (after the timing that the first UE (triggers to) performs the resource sensing (and selection)). Such a case is shown in  FIG. 15B . In other words, the first UE does not perform additional sensing in a time gap between the timing of (triggering to) performing the resource sensing (and selection) and the first slot of the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     Preferably in certain embodiments, if the first UE (triggers to) performs the resource sensing (and selection) in a timing within the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time, the first UE may start to perform additional sensing when the first UE (triggers to) performs the resource sensing (and selection), as shown in  FIG. 15C . Preferably in certain embodiments, the set of (contiguous) slots may be (latter) part of the specific value of (contiguous) slots. Preferably in certain embodiments, the first UE may perform additional sensing for an additional sensing duration. The additional sensing duration may comprise/include at least the set of (contiguous) slots before starting boundary/timing of the one sidelink active time. Preferably in certain embodiments, the additional sensing duration may comprise/include another (contiguous) set of slots starting from starting boundary/timing of the one sidelink active time. Preferably in certain embodiments, summation value of the number of the set of (contiguous) slots and the number of the another set of (contiguous) slots is the same as the specific value. Preferably in certain embodiments, the first UE does not perform additional sensing in a timing within sidelink non-active time, wherein the timing is before the first UE (triggers to) performs the resource sensing (and selection). 
     In one embodiment, whether or not the first UE (triggers to) performs the resource sensing (and selection) in a timing within sidelink non-active time, the first UE may perform additional sensing in the specific value of (contiguous) slots before (each) starting boundary/timing of each sidelink active time. Preferably in certain embodiments, the first UE may perform additional sensing for additional sensing duration, wherein the additional sensing duration comprises/includes/consists of the specific value of (contiguous) slots before starting boundary/timing of each sidelink active time. 
     More specifically, if the first UE (triggers to) performs the resource sensing (and selection) within sidelink non-active time before starting boundary/timing of one sidelink active time, the first UE may perform the additional sensing for the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. If the first UE does not (trigger to) perform the resource sensing (and selection) within sidelink non-active time before starting boundary/timing of one sidelink active time, the first UE may perform the additional sensing for the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. It may mean that the set of (contiguous) slots is the specific value of (contiguous) slots. Such a case is shown in  FIG. 15D . The first UE already performs additional sensing for the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. Even when the first UE (triggers to) performs resource sensing (and selection) in a starting timing of one sidelink active time, the first UE may not require performing additional sensing after the first UE (triggers to) performs the resource sensing (and selection). Thus, sidelink resources in early slots of the one sidelink active time may be selectable or usable for the first UE to perform the first (control and/or data) sidelink transmission. 
     Preferably in certain embodiments, for the additional sensing in sidelink non-active time, the first UE may receive/monitor (only) 1st stage SCI. The first UE may receive/monitor (only) SCI format 1. The first UE may receive/monitor (only) PSCCH. Preferably in certain embodiments, the first UE may not receive/monitor 2 nd  stage SCI. The first UE may not receive/monitor SCI format 2-A/2-B. The first UE may not receive/decode PSSCH. 
     Alternatively, for additional sensing in sidelink non-active time, the first UE may receive/monitor 1st stage SCI and/or 2 nd  stage SCI. The first UE may receive/monitor SCI format 1 and/or SCI format 2-A/2-B. 
     Preferably in certain embodiments, for additional sensing in sidelink active time, the first UE may receive/monitor 1st stage SCI and/or 2 nd  stage SCI. The first UE may receive/monitor SCI format 1 and/or SCI format 2-A/2-B. The first UE may receive/monitor PSCCH for SCI format 1. The first UE may receive/decode PSSCH for receiving SCI format 2-A/2-B. 
     Referring to  FIG. 16 , with this and other concepts and methods of the present invention, a method  1000  of a first device performs sidelink communication to at least a second device and comprises the steps where the first device performs sidelink DRX procedure at step  1002 . The first device receives/monitors SCI in sidelink active time, wherein the sidelink active time is determined/derived based on sidelink DRX configuration/parameters, at step  1004 . The first device performs additional sensing for a set of (contiguous) slots before starting boundary/timing of one sidelink active time, at step  1006 . The first device determines/selects a first sidelink resource based on at least sensing result of the additional sensing, at step  1008 . At step  1010 , the first device performs a first (control and/or data) sidelink transmission on the first sidelink resource for transmitting a sidelink data to the second device. 
     In certain embodiments, the set of (contiguous) slots is the (latter) part of a specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     In certain embodiments, the set of (contiguous) slots is a specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     In certain embodiments, the method further comprises: when/if the first device triggers to perform resource sensing and selection within sidelink non-active time before starting boundary/timing of the one sidelink active time, the first device performs the additional sensing for the set of (contiguous) slots before starting boundary/timing of one sidelink active time. 
     In certain embodiments, the method further comprises: when/if the first device does not trigger to perform resource sensing and selection within sidelink non-active time before starting boundary/timing of the one sidelink active time, the first device does not perform the additional sensing for the set of (contiguous) slots before starting boundary/timing of one sidelink active time. 
     In certain embodiments, if the first device triggers to perform the resource sensing and selection in a timing (in sidelink non-active time) before the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time, the first device starts to perform the additional sensing in the specific value of (contiguous) slots, and/or the first device does not perform the additional sensing before the specific value of (contiguous) slots, and/or the set of (contiguous) slots is the specific value of (contiguous) slots. 
     In certain embodiments, if the first device triggers to perform the resource sensing and selection within the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time, the first device starts to perform the additional sensing when the first device triggers to perform the resource sensing and selection, and/or the set of (contiguous) slots is (latter) part of the specific value of (contiguous) slots, and/or the first device performs additional sensing for an additional sensing duration, wherein the additional sensing duration comprises/includes at least the set of (contiguous) slots and another (contiguous) set of slots starting from starting boundary/timing of the one sidelink active time, and/or wherein summation value of the number of the set of (contiguous) slots and the number of the another set of (contiguous) slots is the same as the specific value. 
     In certain embodiments, the method further comprises: no matter whether or not the first device triggers to perform resource sensing and selection within sidelink non-active time before starting boundary/timing of the one sidelink active time, the first device performs the additional sensing for the set of (contiguous) slots before starting boundary/timing of one sidelink active time, and/or wherein the set of (contiguous) slots is the specific value of (contiguous) slots before starting boundary/timing of the one sidelink active time. 
     In certain embodiments, the first device performs additional sensing for additional sensing duration, wherein the additional sensing duration comprises/includes/consists of the specific value of (contiguous) slots before starting boundary/timing of each sidelink active time. 
     In certain embodiments, the specific value is 31 or 32. 
     In certain embodiments, the specific value is (31+T1), or ceiling function of (31+T1). 
     In certain embodiments, the specific value is (pre-)configured or specified. 
     In certain embodiments, the first device performs the additional sensing in a sidelink resource pool, and/or the specific value is determined based on CBR of the sidelink resource pool. 
     In certain embodiments, the specific value is determined based on a data priority of the sidelink data. 
     In certain embodiments, the specific value is determined based on a latency requirement or (remaining) PDB of the sidelink data. 
     In certain embodiments, for the additional sensing in sidelink non-active time, the first device receives/monitors (only) 1st stage SCI. 
     In certain embodiments, for the additional sensing in sidelink non-active time, the first device receives/monitors 1st stage SCI and/or 2nd stage SCI. 
     Referring back to  FIGS. 3 and 4 , in one or more embodiments, the device  300  includes program code  312  stored in memory  310 . The CPU  308  could execute program code  312  to: (i) perform, at a first device, sidelink communication to at least a second device, and the first device performs sidelink DRX procedure, (ii) receive/monitor, at the first device, SCI in sidelink active time, wherein the sidelink active time is determined/derived based on sidelink DRX configuration/parameters, (iii) perform, at the first device, additional sensing for a set of (contiguous) slots before a starting boundary/timing of one sidelink active time, (iv) determine/select, at the first device, a first sidelink resource based on at least sensing result of the additional sensing, and (v) perform, at the first device, a first (control and/or data) sidelink transmission on the first sidelink resource for transmitting a sidelink data to the second device. Moreover, the CPU  308  can execute the program code  312  to perform all of the described actions, steps, and methods described above, below, or otherwise herein. 
     Referring to  FIG. 17 , with this and other concepts and methods of the present invention, a method  1020  of a first device performs sidelink communication to at least a second device in a sidelink resource pool and comprises the steps where the first device triggers to perform resource selection, for a sidelink data, at a timing at step  1022 . The first device performs sensing for a first contiguous sensing duration before a sidelink on-duration active time of the second device, at step  1024 . The first device determines/selects a first sidelink resource from a set of sidelink resources, at step  1026 , wherein the set of sidelink resources is derived or determined based on at least sensing result in the first contiguous sensing duration, at step  1028 . At step  1030 , the first device performs a first sidelink transmission on the first sidelink resource for transmitting the sidelink data to the second device. 
     In certain embodiments, the sidelink on-duration active time of the second device is the most recent sidelink on-duration active time of the second device after the timing, and/or wherein the first contiguous sensing duration is derived or determined based on (starting boundary/timing of) the sidelink on-duration active time of the second device. 
     In certain embodiments, a specific value is 31, 32, (pre-)configured or specified, and/or wherein the specific value is determined based on a data priority of the sidelink data, and/or wherein the specific value is determined based on a latency requirement or (remaining) packet delay budget of the sidelink data, and/or wherein the specific value is determined based on a Channel Busy Ratio of the sidelink resource pool. 
     In certain embodiments, the timing is before the specific value of (contiguous) TTIs (just) before (starting boundary/timing of) the sidelink on-duration active time of the second device, and/or the first device performs the sensing in the specific value of (contiguous) TTIs in response to the resource selection trigger, and/or the first contiguous sensing duration is or comprises the specific value of (contiguous) TTIs, and/or the first device does not perform the sensing before the first contiguous sensing duration (and after the timing) in response to the trigger to perform resource selection. 
     In certain embodiments, the timing is within the specific value of (contiguous) TTIs (just) before (starting boundary/timing of) the sidelink on-duration active time of the second device, and/or the first device starts to perform the sensing in response to the resource selection trigger, and/or the first contiguous sensing duration comprises latter part of the specific value of (contiguous) TTIs after the timing. 
     In certain embodiments, the first device performs sensing for a second contiguous sensing duration, the second contiguous sensing duration starts from (starting boundary/timing of) the sidelink on-duration active time of the second device, and/or the set of sidelink resources is derived or determined based on sensing result in the first contiguous sensing duration and sensing result in the second contiguous sensing duration, and/or summation of TTI number of the first contiguous sensing duration and TTI number of the second contiguous sensing duration is the same as the specific value. 
     In certain embodiments, whether or not the first device triggers to perform the resource selection, the first device performs the sensing for the first contiguous sensing duration before the sidelink on-duration active time of the second device, and/or the first contiguous sensing duration is or comprises the specific value of (contiguous) TTIs (just) before (starting boundary/timing of) the sidelink on-duration active time of the second device. 
     In certain embodiments, the timing is outside the sidelink on-duration active time of the second device, and/or the first contiguous sensing duration is outside the sidelink on-duration active time of the second device, and/or the first contiguous sensing duration ends in starting boundary/timing of the sidelink on-duration active time of the second device, and/or the first contiguous sensing duration is just before the sidelink on-duration active time of the second device. 
     In certain embodiments, the first device assumes or determines the sidelink on-duration active time of the second device based on a sidelink DRX on-duration timer configuration of the second device, and/or the sidelink on-duration active time includes the time while associated sidelink DRX on-duration timer is running. 
     In certain embodiments, the timing is outside a sidelink on-duration active time of the first device, and/or (part of) the first contiguous sensing duration is outside the sidelink on-duration active time of the first device. 
     In certain embodiments, the timing is (in) a sidelink TTI in the sidelink resource pool. The first contiguous sensing duration consists of sidelink TTIs in the sidelink resource pool, and/or the second contiguous sensing duration consists of sidelink TTIs in the sidelink resource pool, and/or the specific value of (contiguous) TTIs consists of sidelink TTIs in the sidelink resource pool. The first contiguous sensing duration comprises sidelink TTIs in the sidelink resource pool, and/or the second contiguous sensing duration comprises sidelink TTIs in the sidelink resource pool, and/or the specific value of (contiguous) TTIs comprises sidelink TTIs in the sidelink resource pool. 
     In certain embodiments, the sensing for the first contiguous sensing duration does not mean periodic-based partial sensing, and/or the sensing for the first contiguous sensing duration does not mean sensing based on reservation periods. 
     Referring back to  FIGS. 3 and 4 , in one or more embodiments, the device  300  includes program code  312  stored in memory  310 . The CPU  308  could execute program code  312  to: (i) perform, at a first device, sidelink communication to at least a second device in a sidelink resource pool, and the first device triggers to perform resource selection, for a sidelink data, at a timing, (ii) perform, at the first device, sensing for a first contiguous sensing duration before a sidelink on-duration active time of the second device, (iii) determine/select, at the first device, a first sidelink resource from a set of sidelink resources, (iv) derive/determine, at the first device, the set of sidelink resources based on at least sensing result in the first contiguous sensing duration, and (v) perform, at the first device, a first sidelink transmission on the first sidelink resource for transmitting the sidelink data to the second device. Moreover, the CPU  308  can execute the program code  312  to perform all of the described actions, steps, and methods described above, below, or otherwise herein. 
     Any combination of the above concepts or teachings can be jointly combined or formed to one or more new embodiments. The disclosed details and embodiments provided below can be used to solve at least (but not limited to) the issues mentioned above and herein. 
     Preferably in certain embodiments, the starting boundary/timing of one sidelink active time may be the starting slot boundary/starting slot timing of the one sidelink active time. 
     Preferably in certain embodiments, the starting boundary/timing of one sidelink active time may be the starting symbol boundary/starting symbol timing of the one sidelink active time. Preferably in certain embodiments, the symbol is a first symbol available for sidelink transmission in a slot. 
     Preferably in certain embodiments, the first UE may (trigger to) perform the resource sensing (and selection), when/if the first UE requires sidelink resource for delivering/transmitting the sidelink data. Preferably in certain embodiments, the first sidelink (control and/or data) transmission is a new/initial sidelink transmission of the sidelink data. Preferably in certain embodiments, the first sidelink (control and/or data) transmission is a sidelink retransmission of the sidelink data. 
     Preferably in certain embodiments, the sidelink data may mean a TB. Preferably in certain embodiments, the transport block may mean/be a MAC PDU. 
     Preferably in certain embodiments, the aperiodic sidelink data may mean a transport block, wherein a “Resource reservation period” field in SCI scheduling the transport block indicates zero value of reservation period. 
     Preferably in certain embodiments, the periodic sidelink data may mean a transport block, wherein a “Resource reservation period” field in SCI scheduling the transport block indicates non-zero value of reservation period. 
     Preferably in certain embodiments, the time unit of the additional sensing duration may be a slot. 
     Preferably in certain embodiments, the time unit of the (contiguous) time interval may be a slot. 
     Preferably in certain embodiments, the slot may mean sidelink slot. 
     Preferably in certain embodiments, the first UE may perform the resource sensing (and selection) in a sidelink resource pool. Preferably in certain embodiments, the first UE may perform the additional sensing in the sidelink resource pool. Preferably in certain embodiments, the first UE may perform the sidelink DRX in the sidelink resource pool. Preferably in certain embodiments, the slot may mean/comprise sidelink slot associated with the sidelink resource pool. Preferably in certain embodiments, the slot may not mean/comprise sidelink slot associated with other sidelink resource pool. 
     Preferably in certain embodiments, the contiguous slots in the sidelink resource pool may be not contiguous in the physical slot. It means that the contiguous slots in the sidelink resource pool may be not contiguous from the aspect of the physical slot. Preferably in certain embodiments, the contiguous slots in the sidelink resource pool may be not contiguous in sidelink slots in a carrier/cell. It means that the contiguous slots in the sidelink resource pool may be not contiguous from the aspect of sidelink slots in a carrier/cell. Preferably in certain embodiments, there may be one or more sidelink resource pools in a carrier/cell. 
     Preferably in certain embodiments, the additional sensing may mean/comprise short sensing before performing the resource selection or before a resource selection window. Preferably in certain embodiments, the additional sensing may mean/comprise short sensing before candidate resources for the resource sensing and selection. 
     Preferably in certain embodiments, the additional sensing may mean/comprise sensing for a time duration before candidate resources for the resource sensing and selection. 
     Preferably in certain embodiments, the additional sensing may mean/comprise contiguous sensing. Preferably in certain embodiments, the additional sensing in the additional sensing duration may mean/comprise contiguous sensing at least in the (contiguous) additional sensing duration. Preferably in certain embodiments, the additional sensing does not mean periodic-based partial sensing. Preferably in certain embodiments, the additional sensing does not mean sensing based on reservation periods. 
     Preferably in certain embodiments, the partial sensing may mean/comprise periodic-based periodic sensing and/or additional sensing. Preferably in certain embodiments, the partial sensing may mean/comprise periodic-based periodic sensing and/or contiguous sensing. Preferably in certain embodiments, the periodic-based partial sensing may mean/comprise sensing based on the set of (reservation) periods. Preferably in certain embodiments, the periodic-based partial sensing may mean/comprise sensing on slots/resources associated with candidate resources for the resource sensing and selection, where the association is based on the set of (reservation) periods. Preferably in certain embodiments, the set of (reservation) periods is (pre-)configured. Preferably in certain embodiments, the set of (reservation) periods is (pre-)configured for the first UE. 
     Preferably in certain embodiments, the set of (reservation) periods is (pre-)configured for the sidelink resource pool. Preferably in certain embodiments, the set of (reservation) periods is specified. Preferably in certain embodiments, the set of (reservation) periods may be/comprise all or part of supported reservation periods in the sidelink resource pool. Preferably in certain embodiments, the set of (reservation) periods may be/comprise reservation periods with a period value larger than the specific value. Preferably in certain embodiments, the set of (reservation) periods may be/comprise reservation periods with a period value larger than the specific value. It means the set of (reservation) periods for periodic-based partial sensing may be/comprise some reservation periods, which are not covered in additional sensing (duration). It is because the resource reservation information for sidelink data with reservation period value smaller than specific value may be acquired via additional sensing. Preferably in certain embodiments, the (reservation) period value may be in unit of milliseconds. Preferably in certain embodiments, for comparing with the specific value, the (reservation) period value may be (converted/changed) in unit of slots. 
     Preferably in certain embodiments, the set of (reservation) periods may be determined/derived based on sidelink DRX configuration. Preferably in certain embodiments, the set of (reservation) periods may be determined/derived based on sidelink DRX cycle and/or on-duration timer. 
     Preferably in certain embodiments, the first UE acquires resource reservation information from the one or more other UEs via received SCI from the one or more other UEs. Preferably in certain embodiments, the SCI from the one or more other UEs includes resource reservation information of the other UE. 
     Preferably in certain embodiments, the sidelink data is for a second UE. Preferably in certain embodiments, the first UE performs the first (control and/or data) sidelink transmission on the first sidelink resource for delivering/transmitting the sidelink data to the second UE. 
     Preferably in certain embodiments, the first UE may have/maintain/establish a sidelink link/connection with the second UE on PC5 interface. Preferably in certain embodiments, the sidelink DRX is performed/operated for sidelink communication between the first UE and the second UE. Preferably in certain embodiments, the sidelink DRX configuration is configured for the sidelink link/connection between the first UE and the second UE. Preferably in certain embodiments, the sidelink DRX configuration is configured for the first UE. Preferably or alternatively in certain embodiments, the sidelink DRX configuration is configured for the second UE. 
     Preferably in certain embodiments, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink link/connection between the first UE and the second UE. Preferably in certain embodiments, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the second UE. Preferably or alternatively in certain embodiments, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     Preferably in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink link/connection between the first UE and the second UE. Preferably in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the second UE. Preferably or alternatively in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink link/connection between the first UE and the second UE. The sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink link/connection between the first UE and the second UE. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the second UE. The sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the second UE. The sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the second UE. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. The sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     Preferably in certain embodiments, the first UE may have/maintain/establish a sidelink link/connection with a sidelink group on PC5 interface, wherein the sidelink group comprises at least the first UE and the second UE. Preferably in certain embodiments, the sidelink DRX is performed/operated for sidelink communication of the sidelink group. Preferably in certain embodiments, the sidelink DRX configuration is configured for the sidelink group. Preferably in certain embodiments, the sidelink DRX configuration is configured for the first UE. 
     Preferably in certain embodiments, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink group. Preferably or alternatively in certain embodiments, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     Preferably in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink group. Preferably or alternatively in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink group. Preferably in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink group. 
     In one embodiment, the sidelink active time, associated with the additional sensing, is associated/derived/determined based on sidelink DRX configuration for the sidelink group. Preferably in certain embodiments, the sidelink active time, associated with the partial sensing, is associated/derived/determined based on sidelink DRX configuration for the first UE. 
     Preferably in certain embodiments, the first UE may determine/derive the resource selection window based on sidelink active time of the second UE—e.g., the resource selection window is (restricted/limited) within the sidelink active time of the second UE. Preferably in certain embodiments, the first UE may determine/derive the resource selection window based on sidelink DRX configuration for the second UE. Preferably or alternatively in certain embodiments, the first UE may determine/derive the resource selection window based on sidelink DRX configuration for the first UE. Preferably or alternatively in certain embodiments, the first UE may determine/derive the resource selection window based on sidelink DRX configuration for the sidelink link/connection between the first UE and the second UE. Preferably or alternatively in certain embodiments, the first UE may determine/derive the resource selection window based on sidelink DRX configuration for the sidelink group. 
     Preferably in certain embodiments, the first UE may have/maintain/establish multiple sidelink links/connections on PC5 interface. For different sidelink links/connections, the first UE may perform sidelink transmission/reception to/from different paired UEs. 
     Preferably in certain embodiments, the first UE may have/maintain/establish a first sidelink link/connection and a second sidelink link/connection. The paired UEs of the first sidelink link/connection may be different from the paired UEs of the second sidelink link/connection. Preferably in certain embodiments, the one or more sidelink logical channels associated with (the paired UEs of) the first sidelink link/connection are separate/independent from the one or more sidelink logical channels associated with (the paired UEs of) the second sidelink link/connection. 
     Preferably in certain embodiments, the data packet is associated with at least a sidelink logical channel Preferably in certain embodiments, the sidelink data comes from at least a sidelink logical channel. 
     Preferably in certain embodiments, the sidelink data transmission may be/mean PSSCH transmission. 
     Preferably in certain embodiments, the sidelink control transmission may be/mean PSCCH transmission. 
     Preferably in certain embodiments, the SCI may be delivered at least in PSCCH. Preferably in certain embodiments, the sidelink control information may comprise 1st stage SCI. Preferably in certain embodiments, the 1st stage SCI may be transmitted via PSCCH. Preferably in certain embodiments, the sidelink control information may comprise 2nd stage SCI. Preferably in certain embodiments, the 2nd stage SCI may be transmitted via multiplexed with PSSCH. Preferably in certain embodiments, the SCI format 1 is 1st stage SCI. Preferably in certain embodiments, the SCI format 2-A is a 2nd stage SCI. Preferably in certain embodiments, the SCI format 2-B is a 2nd stage SCI. 
     Preferably in certain embodiments, the sidelink slot may mean slot for sidelink. Preferably in certain embodiments, a sidelink slot may be represented as a TTI. Preferably in certain embodiments, a TTI may be a subframe (for sidelink). Preferably in certain embodiments, a TTI comprises multiple symbols, e.g., 12 or 14 symbols. Preferably in certain embodiments, the TTI may be a slot (fully/partially) comprising sidelink symbols. Preferably in certain embodiments, the TTI may mean a transmission time interval for a sidelink (data) transmission. Preferably in certain embodiments, a sidelink slot or a slot for sidelink may contain all OFDM symbols available for sidelink transmission. Preferably in certain embodiments, a sidelink slot or a slot for sidelink may contain a consecutive number symbols available for sidelink transmission. Preferably in certain embodiments, a sidelink slot or a slot for sidelink means that a slot is included in a sidelink resource pool. 
     Preferably in certain embodiments, the symbol may mean a symbol indicated/configured for sidelink. 
     Preferably in certain embodiments, a sub-channel is a unit for sidelink resource allocation/scheduling (for PSSCH). Preferably in certain embodiments, a sub-channel may comprise multiple contiguous Physical Resource Blocks (PRBs) in frequency domain. Preferably in certain embodiments, the number of PRBs for each sub-channel may be (pre-)configured for a sidelink resource pool. Preferably in certain embodiments, a sidelink resource pool (pre-)configuration may indicate/configure the number of PRBs for each sub-channel Preferably in certain embodiments, the number of PRBs for each sub-channel may be any of 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 25, 30, 48, 50, 72, 75, 96, 100. Preferably in certain embodiments, a sub-channel may be represented as a unit for sidelink resource allocation/scheduling. Preferably in certain embodiments, a sub-channel may mean a PRB. Preferably in certain embodiments, a sub-channel may mean a set of consecutive PRBs in frequency domain. Preferably in certain embodiments, a sub-channel may mean a set of consecutive resource elements in frequency domain Preferably in certain embodiments, the UE may be/mean/comprise/replace a device. 
     Preferably in certain embodiments, the sidelink transmission/reception may be UE-to-UE transmission/reception. Preferably in certain embodiments, the sidelink transmission/reception may be device-to-device transmission/reception. Preferably in certain embodiments, the sidelink transmission/reception may be V2X transmission/reception. Preferably in certain embodiments, the sidelink transmission/reception may be Pedestrian-to-Everything (P2X) transmission/reception. Preferably in certain embodiments, the sidelink transmission/reception may be on PC5 interface. 
     Preferably in certain embodiments, the PC5 interface may be wireless interface for communication between device and device. Preferably in certain embodiments, the PC5 interface may be wireless interface for communication between devices. Preferably in certain embodiments, the PC5 interface may be wireless interface for communication between UEs. Preferably in certain embodiments, the PC5 interface may be wireless interface for V2X or P2X communication. Preferably in certain embodiments, the Uu interface may be wireless interface for communication between network node and device. Preferably in certain embodiments, the Uu interface may be wireless interface for communication between network node and UE. 
     Preferably in certain embodiments, the first UE may be a first device. Preferably in certain embodiments, the first device may be a vehicle UE. Preferably in certain embodiments, the first device may be a V2X UE. 
     Preferably in certain embodiments, the second UE may be a second device. Preferably in certain embodiments, the second device may be a vehicle UE. Preferably in certain embodiments, the second device may be a V2X UE. 
     Preferably in certain embodiments, the first UE and the second device are different devices. 
     Any combination of the above concepts or teachings can be jointly combined or formed to a new embodiment. The disclosed details and embodiments can be used to solve at least (but not limited to) the issues mentioned above and herein. 
     It is noted that any of the methods, alternatives, steps, examples, and embodiments proposed herein may be applied independently, individually, and/or with multiple methods, alternatives, steps, examples, and embodiments combined together. 
     Various aspects of the disclosure have been described above. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. As an example of some of the above concepts, in some aspects, concurrent channels may be established based on pulse repetition frequencies. In some aspects, concurrent channels may be established based on pulse position or offsets. In some aspects, concurrent channels may be established based on time hopping sequences. In some aspects, concurrent channels may be established based on pulse repetition frequencies, pulse positions or offsets, and time hopping sequences. 
     Those of ordinary skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. 
     Those of ordinary skill in the art would further appreciate that the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two, which may be designed using source coding or some other technique), various forms of program or design code incorporating instructions (which may be referred to herein, for convenience, as “software” or a “software module”), or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. 
     In addition, the various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit (“IC”), an access terminal, or an access point. The IC may comprise a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute codes or instructions that reside within the IC, outside of the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     It is understood that any specific order or hierarchy of steps in any disclosed process is an example of a sample approach. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module (e.g., including executable instructions and related data) and other data may reside in a data memory such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. A sample storage medium may be coupled to a machine such as, for example, a computer/processor (which may be referred to herein, for convenience, as a “processor”) such the processor can read information (e.g., code) from and write information to the storage medium. A sample storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in user equipment. In the alternative, the processor and the storage medium may reside as discrete components in user equipment. Moreover, in some aspects, any suitable computer-program product may comprise a computer-readable medium comprising codes relating to one or more of the aspects of the disclosure. In some aspects, a computer program product may comprise packaging materials. 
     While the invention has been described in connection with various aspects and examples, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.