Patent Publication Number: US-11641668-B2

Title: Uplink designs for new radio unlicensed spectrum

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION(S) 
     The present disclosure is part of a non-provisional application claiming the priority benefit of U.S. Patent Application No. 62/738,045, filed on 28 Sep. 2018, the content of which being incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to wireless communications and, more particularly, to uplink (UL) designs for New Radio (NR) unlicensed spectrum (NR-U) operation in mobile communications. 
     BACKGROUND 
     Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted as prior art by inclusion in this section. 
     Under the 3 rd  Generation Partnership Project (3GPP) specifications, physical random access channel (PRACH) transmission by a user equipment (UE) is necessary for standalone NR-U operation. The transmission of physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH) should not block the transmission of a PRACH preamble. However, in situations in which a first UE is to perform a PUSCH or PUCCH transmission to a network node (e.g., gNB) of a mobile network when a second UE is to transmit a PRACH preamble to the network node, there may be an issue with the transmission of the PUSCH/PUCCH by the first UE blocking the transmission of PRACH by the second UE, and vice versa, when propagation delays between the first UE and the second UE and between the second UE and the network node are unknown to the network node. Therefore, there is a need for a solution to address this issue for NR-U operation. 
     Additionally, under current 3GPP specification, the payload size of NR PUCCH format 0/1 tends to be small (with only one or two bits), and NR PUCCH format 0/1/4 occupies merely one physical resource block (PRB). Moreover, the multiplexing capacity of NR PUCCH format 2/3 is merely 1 (i.e., only one PUCCH on the same resource). Thus, the resource mapping needs to be modified to allow for a more efficient way for uplink control information (UCI) transmission. 
     SUMMARY 
     The following summary is illustrative only and is not intended to be limiting in any way. That is, the following summary is provided to introduce concepts, highlights, benefits and advantages of the novel and non-obvious techniques described herein. Select implementations are further described below in the detailed description. Thus, the following summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. 
     In one aspect, a method may involve a processor of an apparatus receiving from a network node a scheduling of a plurality of starting slots for an UL transmission by the apparatus. The method may also involve the processor performing a listen-before-talk (LBT) procedure. The method may further involve the processor performing the UL transmission with an initial slot of the UL transmission in one of the plurality of starting slots based on a result of the LBT procedure. 
     In one aspect, a method may involve a processor of an apparatus detecting an existence of any preamble transmitted by another apparatus. Based on a result of the detecting, the method may involve the processor performing an LBT procedure followed by an UL transmission responsive to a preamble transmitted by one other apparatus being detected. Alternatively, based on the result of the detecting, the method may involve the processor performing the UL transmission without first performing the LBT procedure responsive to no preamble being detected. 
     It is noteworthy that, although description provided herein may be in the context of certain radio access technologies, networks and network topologies such as NR, the proposed concepts, schemes and any variation(s)/derivative(s) thereof may be implemented in, for and by other types of radio access technologies, networks and network topologies such as, for example and without limitation, 5 th  Generation (5G), Long-Term Evolution (LTE), LTE-Advanced, LTE-Advanced Pro and any future-developed networks and technologies. Thus, the scope of the present disclosure is not limited to the examples described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of the present disclosure. The drawings illustrate implementations of the disclosure and, together with the description, serve to explain the principles of the disclosure. It is appreciable that the drawings are not necessarily in scale as some components may be shown to be out of proportion than the size in actual implementation in order to clearly illustrate the concept of the present disclosure. 
         FIG.  1    is a diagram of an example network environment in which various solutions and schemes in accordance with the present disclosure may be implemented. 
         FIG.  2    is a diagram of an example scenario in accordance with an implementation of the present disclosure. 
         FIG.  3    is a diagram of an example scenario in accordance with an implementation of the present disclosure. 
         FIG.  4    is a block diagram of an example communication environment in accordance with an implementation of the present disclosure. 
         FIG.  5    is a flowchart of an example process in accordance with an implementation of the present disclosure. 
         FIG.  6    is a flowchart of an example process in accordance with an implementation of the present disclosure. 
         FIG.  7    is a diagram of an example scenario of PUSCH being blocked by PRACH. 
         FIG.  8    is a diagram of an example scenario of PRACH being blocked by PUSCH. 
         FIG.  9    is a diagram of an example scenario of PRACH being not blocked by PUSCH in accordance with an implementation of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS 
     Detailed embodiments and implementations of the claimed subject matters are disclosed herein. However, it shall be understood that the disclosed embodiments and implementations are merely illustrative of the claimed subject matters which may be embodied in various forms. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments and implementations set forth herein. Rather, these exemplary embodiments and implementations are provided so that description of the present disclosure is thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art. In the description below, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments and implementations. 
     Overview 
     Implementations in accordance with the present disclosure relate to various techniques, methods, schemes and/or solutions pertaining to UL designs for NR-U operation in mobile communications. According to the present disclosure, a number of possible solutions may be implemented separately or jointly. That is, although these possible solutions may be described below separately, two or more of these possible solutions may be implemented in one combination or another. 
       FIG.  1    illustrates an example network environment  100  in which various solutions and schemes in accordance with the present disclosure may be implemented. The following description of various proposed schemes is provided with reference to  FIG.  1   . 
     Referring to  FIG.  1   , network environment  100  may involve a first UE  110  (denoted as “UE 0 ” in  FIG.  1   ), a second UE  120  (denoted as “UE 1 ” in  FIG.  1   ), and a network node  130  (denoted as “gNB” in  FIG.  1   , although network node  130  may also be an eNB or a transmit/receive point (TRP)) of a wireless network (e.g., 5G/NR mobile network). In network environment  100 , each of first UE  110  and second UE  120  may be configured to implement various schemes pertaining to UL designs for NR-U operation in mobile communications in accordance with the present disclosure, as described below. 
     For better appreciation of advantages and benefits provided by various proposed schemes in accordance with the present disclosure, considering first a case with the following assumptions with respect to network environment  100 : (1) time t 0  is the propagation delay between first UE  110  and network node  130 ; (2) time t 1  is the propagation delay between second UE  120  and network node  130 ; (3) time t 2  is the propagation delay between first UE  110  and second UE  120 ; (4) t 0  is known to network node  130  but t 0  and t 2  are unknown to network node  130 ; (5) first UE  110  has PUSCH or PUCCH to be transmitted; and (6) second UE  120  has PRACH preamble to be transmitted, with the PRACH preamble occupying twelve orthogonal frequency-division multiplexing (OFDM) symbols (15 kHz) and starting from second OFDM symbols. However, due to the unknown propagation delays t 1  and t 2 , the transmission of PUSCH/PUCCH by first UE  110  may block the transmission of PRACH by second UE  120 , and vice versa. For illustration,  FIG.  7    illustrates an example scenario  700  of PUSCH being blocked by PRACH, and  FIG.  8    illustrates an example scenario  800  of PRACH being blocked by PUSCH. 
     Part (A) of  FIG.  7    shows the timing at network node  130  (denoted as “gNB”) and part (B) of  FIG.  7    shows the timing at first UE  110  (denoted as “UE 0 ”). Referring to  FIG.  7   , in this example, it is assumed that second UE  120  chooses the random access channel (RACH) resource in slot n to transmit a PRACH preamble, and network node  130  schedules the PUSCH/PUCCH (denoted as “PUXCH” in  FIG.  7   ) of first UE  110  from slot n+1 to slot n+3. To align the timing at network node  130 , first UE  110  will start the transmission of PUSCH/PUCCH at time t+T slot −t 0 , with T slot  being the slot duration. As second UE  120  does not know its timing advance, transmission of the PRACH preamble is started from time t+2*T OFDM +t 1 , with T OFDM  being an OFDM symbol time. Since PRACH is transmitted by second UE  120  before the scheduled PUSCH/PUCCH transmission, the transmission of PUSCH/PUCCH by first UE  110  is blocked by the PRACH. 
     Part (A) of  FIG.  8    shows the timing at network node  130  (denoted as “gNB”) and part (B) of  FIG.  8    shows the timing at second UE  120  (denoted as “UE 1 ”). Referring to  FIG.  8   , in this example, it is assumed that second UE  120  chooses the RACH resource in slot n to transmit a PRACH preamble, and network node  130  schedules the PUSCH/PUCCH (denoted as “PUXCH” in  FIG.  8   ) of first UE  110  from slot n to slot n+3. To align the timing at network node  130 , first UE  110  will start the transmission of PUSCH/PUCCH at time t−t 0 . As second UE  120  does not know its timing advance, transmission of the PRACH preamble is started from time t+2*T OFDM +t 1 , with T OFDM  being an OFDM symbol time. Since PUSCH/PUCCH is transmitted by first UE  110  before the scheduled PRACH transmission, the transmission of PRACH by second UE  120  is blocked by the PUSCH/PPUCCH. 
     To prevent the above-described situations from happening, various proposed schemes in accordance with the present disclosure may involve network node  130  configuring multiple starting transmission positions (or time slots) for PUSCH/PUCCH transmission and first UE  110  deciding in which of the multiple starting transmission positions (or time slots) to start the PUSCH/PUCCH transmission based on a result of LBT. Moreover, various proposed schemes in accordance with the present disclosure may involve first UE  110  using a preamble to inform other UEs (e.g., second UE  120 ) that the current PUSCH/PUCCH transmission is for the same cell/network node (e.g., network node  130 ) with which the other UEs are associated. 
     With respect to the issue of PUSCH/PUCCH transmission being blocked by PRACH transmission, it is plausible that there may be some gaps in the beginning of the PUSCH/PUCCH transmission, which may be achieved by scheduling from network node  130 . However, this may lead to a waste of resources in an event that second UE  120  does not choose slot n to transmit the PRACH preamble. Thus, to achieve an efficient UL transmission, under a proposed scheme in accordance with the present disclosure, multiple starting positions (or time slots) may be configured by network node  130  for the transmission of a PUSCH/PUCCH burst. The starting position may be decided by first UE  110  based on results of an LBT procedure performed by first UE  110 . 
     With respect to the issue of PRACH transmission being blocked by PUSCH/PUCCH transmission, under a proposed scheme in accordance with the present disclosure, the PUSCH/PUCCH transmission by first UE  110  may be preceded by a preamble for detection by second UE  120  so as to avoid the blocking issue.  FIG.  9    illustrates an example scenario  900  of PRACH being not blocked by PUSCH in accordance with the proposed scheme. Part (A) of  FIG.  9    shows the timing at network node  130  (denoted as “gNB”) and part (B) of  FIG.  9    shows the timing at second UE  120  (denoted as “UE 1 ”). 
     Under the proposed scheme, preamble may be cell-specific, and it may be configured by remaining minimum system information (RMSI) or radio resource control (RRC) signaling from network node  130 . The preamble may indicate the duration of the PUSCH/PUCCH transmission and/or an identification (ID) of the serving cell for first UE  110  (e.g., an ID of a cell corresponding to network node  130 ). Accordingly, second UE  120  may detect the existence of the preamble before transmitting a PRACH preamble and, thus, the PRACH would not be blocked due to the preamble transmitted by first UE  110  being detected by second UE  120 . In an event that second UE  120  detects the preamble transmitted by first UE  110  and that second UE  120  determines that the detected preamble belongs to the serving cell of second UE  120  while the intended PRACH transmission is at least partially inside the duration of the PUSCH/PUCCH transmission by first UE  110  as indicated by the detected preamble, second UE  120  may take either of two options. Under a first option, second UE  120  may assume that the communication channel is idle (which is equivalent to success of LBT) and thus may proceed with the PRACH transmission. The assumption here is that network node  130  may have scheduled first UE  110  and second UE  120  to transmit in different frequencies although in time domain there may be an overlap. Under a second option, second UE  120  may perform an LBT procedure before the transmission of its PRACH preamble and, upon a successful LBT (e.g., no transmission by first UE  110  or any other UE being detected), proceed with the PRACH transmission. 
     Given the uncertainty of LBT and the regulatory requirement on occupied channel bandwidth (OCB), it may be beneficial to take UE multiplexing capacity into the PUCCH design consideration. To overcome the uncertainty of LBT and improve spectral efficiency in the unlicensed band, a network may schedule UL transmission of multiple UEs within the same channel occupancy time. However, due to the OCB requirement, the number of interlaces per symbol is limited. Thus, multiplexing more than one PUCCH in the same resource may be necessary. 
     Under a proposed scheme in accordance with the present disclosure, NR PUCCH format 2 and format 3 may be modified to support UE multiplexing. For instance, when performing a PUCCH transmission, a UE (e.g., first UE  110 ) may perform the PUCCH transmission with orthogonal covering code (OCC) applied to a PUCCH format to support multiplexing. For instance, first UE  110  may perform the PUCCH transmission with the OCC applied to PUCCH format 2 or format 3 to support multiplexing by code-division multiplexing (CDM). The length of the OCC may be 2 or 4. To help better appreciate advantages and benefits provided by the proposed scheme,  FIG.  2    illustrates an example scenario  200  in accordance with an implementation of the present disclosure, and  FIG.  3    illustrates an example scenario  300  in accordance with an implementation of the present disclosure. 
     Referring to  FIG.  2   , scenario  200  may involve modified PUCCH format 2 (short PUCCH) with CDM 2/4. For CDM 2, for the data to be transmitted, the transmitting UE may apply the following OCCs: {1 1 1 1 1 1 1 1} and {1 −1 1 −1 1 −1 1 −1}. For CDM 2, the transmitting UE may transmit two orthogonal reference signal (RS) sequences, with the length of the sequences depending on the bandwidth. For CDM 4, for the data to be transmitted, the transmitting UE may apply the following OCCs: {1 1 1 1 1 1 1 1}, {1 −j −1 j 1− j −1 j}, {1 −1 1 −1 1 −1 1 −1}, and {1 j −1 −j 1 j −1 −j}. For CDM 4, the transmitting UE may transmit four orthogonal RS sequences, with the length of the sequences depending on the bandwidth. 
     Referring to  FIG.  3   , scenario  300  may involve modified PUCCH format 2 (short PUCCH) with CDM 2/4. Different from scenario  200 , in scenario  300  the RS is located at {0, 3, 6, 9}. Other than that, description above with respect to scenario  200  also applies to scenario  300 . 
     Illustrative Implementations 
       FIG.  4    illustrates an example communication environment  400  having an example apparatus  410  and an example apparatus  420  in accordance with an implementation of the present disclosure. Each of apparatus  410  and apparatus  420  may perform various functions to implement schemes, techniques, processes and methods described herein pertaining to UL designs for NR-U operation in mobile communications, including various schemes described above as well as processes  500  and  600  described below. 
     Each of apparatus  410  and apparatus  420  may be a part of an electronic apparatus, which may be a UE such as a vehicle, a portable or mobile apparatus, a wearable apparatus, a wireless communication apparatus or a computing apparatus. For instance, each of apparatus  410  and apparatus  420  may be implemented in an electronic control unit (ECU) of a vehicle, a smartphone, a smartwatch, a personal digital assistant, a digital camera, or a computing equipment such as a tablet computer, a laptop computer or a notebook computer. Each of apparatus  410  and apparatus  420  may also be a part of a machine type apparatus, which may be an IoT or NB-IoT apparatus such as an immobile or a stationary apparatus, a home apparatus, a wire communication apparatus or a computing apparatus. For instance, each of apparatus  410  and apparatus  420  may be implemented in a smart thermostat, a smart fridge, a smart door lock, a wireless speaker or a home control center. Alternatively, each of apparatus  410  and apparatus  420  may be implemented in the form of one or more integrated-circuit (IC) chips such as, for example and without limitation, one or more single-core processors, one or more multi-core processors, or one or more complex-instruction-set-computing (CISC) processors. Each of apparatus  410  and apparatus  420  may include at least some of those components shown in  FIG.  4    such as a processor  412  and a processor  422 , respectively. Each of apparatus  410  and apparatus  420  may further include one or more other components not pertinent to the proposed scheme of the present disclosure (e.g., internal power supply, display device and/or user interface device), and, thus, such component(s) of each of apparatus  410  and apparatus  420  are neither shown in  FIG.  4    nor described below in the interest of simplicity and brevity. 
     In some implementations, at least one of apparatus  410  and apparatus  420  may be a part of an electronic apparatus, which may be a vehicle, a roadside unit (RSU), network node or base station (e.g., eNB, gNB or TRP), a small cell, a router or a gateway. For instance, at least one of apparatus  410  and apparatus  420  may be implemented in a vehicle in a vehicle-to-vehicle (V2V) or vehicle-to-everything (V2X) network, an eNodeB in an LTE, LTE-Advanced or LTE-Advanced Pro network or in a gNB in a 5G, NR, IoT or NB-IoT network. Alternatively, at least one of apparatus  410  and apparatus  420  may be implemented in the form of one or more IC chips such as, for example and without limitation, one or more single-core processors, one or more multi-core processors, or one or more CISC processors. 
     In one aspect, each of processor  412  and processor  422  may be implemented in the form of one or more single-core processors, one or more multi-core processors, or one or more CISC processors. That is, even though a singular term “a processor” is used herein to refer to processor  412  and processor  422 , each of processor  412  and processor  422  may include multiple processors in some implementations and a single processor in other implementations in accordance with the present disclosure. In another aspect, each of processor  412  and processor  422  may be implemented in the form of hardware (and, optionally, firmware) with electronic components including, for example and without limitation, one or more transistors, one or more diodes, one or more capacitors, one or more resistors, one or more inductors, one or more memristors and/or one or more varactors that are configured and arranged to achieve specific purposes in accordance with the present disclosure. In other words, in at least some implementations, each of processor  412  and processor  422  is a special-purpose machine specifically designed, arranged and configured to perform specific tasks including UL designs for NR-U operation in mobile communications in accordance with various implementations of the present disclosure. 
     In some implementations, apparatus  410  may also include a transceiver  416 , as a communication device, coupled to processor  412  and capable of wirelessly transmitting and receiving data. In some implementations, apparatus  410  may further include a memory  414  coupled to processor  412  and capable of being accessed by processor  412  and storing data therein. In some implementations, apparatus  420  may also include a transceiver  426 , as a communication device, coupled to processor  422  and capable of wirelessly transmitting and receiving data. In some implementations, apparatus  420  may further include a memory  424  coupled to processor  422  and capable of being accessed by processor  422  and storing data therein. Accordingly, apparatus  410  and apparatus  420  may wirelessly communicate with each other via transceiver  416  and transceiver  426 , respectively. 
     To aid better understanding, the following description of the operations, functionalities and capabilities of each of apparatus  410  and apparatus  420  is provided in the context of a NR communication environment in which apparatus  410  is implemented in or as a wireless communication device, a communication apparatus or a UE (e.g., first UE  110 ) and apparatus  420  is implemented in or as a wireless communication device, a communication apparatus or another UE (e.g., second UE  120 ) in a network environment (e.g., network environment  100 ). 
     In one aspect of UL designs for NR-U operation in mobile communications in accordance with the present disclosure, processor  412  of apparatus  410  (as first UE  110 ) may receive, via transceiver  416 , from a network node (e.g., network node  130 ) a scheduling of a plurality of starting slots for an UL transmission by apparatus  410 . Additionally, processor  412  may perform, via transceiver  416 , a listen-before-talk (LBT) procedure. Moreover, processor  412  may perform, via transceiver  416 , the UL transmission with an initial slot of the UL transmission in one of the plurality of starting slots based on a result of the LBT procedure. 
     In some implementations, in performing the UL transmission with the initial slot of the UL transmission in one of the plurality of starting slots based on the result of the LBT procedure, processor  412  may perform certain operations. For instance, processor  412  may select a first starting slot of the plurality of starting slots to begin the UL transmission responsive to the result of the LBT procedure indicating no other transmission in the first starting slot. Moreover, processor  412  may select a second starting slot of the plurality of starting slots after the first starting slot to begin the UL transmission responsive to the result of the LBT procedure indicating at least one other transmission in the first starting slot. 
     In some implementations, the at least one other transmission may include a PRACH transmission by another apparatus (e.g., apparatus  420 ). 
     In some implementations, in performing the UL transmission, processor  412  may perform the UL transmission with an initial slot of the UL transmission preceded by a preamble. In some implementations, the preamble may be cell-specific with respect to a cell with which apparatus  410  is associated. In some implementations, the preamble may be configured by RMSI or RRC signaling from the network node. In some implementations, the preamble may indicate a duration of the UL transmission. Alternatively, or additionally, the preamble may indicate an identification of a serving cell. 
     In some implementations, in performing the LBT procedure, processor  412  may perform certain operations. For instance, processor  412  may detect an existence of any preamble before performing the UL transmission. Based on a result of the detecting, processor  412  may perform the LBT procedure before the UL transmission in response to a preamble transmitted by one other apparatus being detected. Alternatively, processor  412  may skip the LBT procedure before the UL transmission in response to no preamble being detected. In some implementations, the UL transmission may include a PRACH transmission, a PUSCH transmission, a PUCCH transmission, or a sounding reference signal (SRS) transmission. 
     In some implementations, in performing the LBT procedure, processor  412  may perform the LBT procedure based on the preamble transmitted by one other apparatus being detected plus on one or more of: (a) the detected preamble belonging to a same serving cell with which the apparatus is associated; and (b) the UL transmission being within a duration of one other UL transmission by the other apparatus as indicated in the preamble. In some implementations, the UL transmission may include a PRACH transmission. In such cases, the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the UL transmission, processor  412  may perform a PUCCH transmission with OCC applied to a PUCCH format to support multiplexing. In some implementations, in performing the PUCCH transmission with the OCC applied to the PUCCH format to support multiplexing, processor  412  may perform the PUCCH transmission with the OCC applied to PUCCH format 2 or format 3 to support multiplexing by CDM. In some implementations, a length of the OCC may be 2 or 4. 
     In another aspect of UL designs for NR-U operation in mobile communications in accordance with the present disclosure, processor  422  of apparatus  420  (as second UE  120 ) may detect, via transceiver  426 , an existence of any preamble transmitted by another apparatus (e.g., apparatus  410 ). Based on a result of the detecting, processor  422  may perform different operations. For instance, processor  422  may perform, via transceiver  426 , an LBT procedure followed by an UL transmission in response to a preamble transmitted by one other apparatus (e.g., apparatus  410 ) being detected. Alternatively, processor  422  may perform, via transceiver  426 , the UL transmission without first performing the LBT procedure in response to no preamble being detected. 
     In some implementations, the UL transmission may include a PRACH transmission. In such cases, the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the LBT procedure processor  422  may perform the LBT procedure based on the preamble transmitted by one other apparatus being detected plus on one or more of: (a) the detected preamble belonging to a same serving cell with which the apparatus is associated; and (b) the UL transmission being within a duration of one other UL transmission by the other apparatus as indicated in the preamble. In such cases, the UL transmission may include a PRACH transmission, and the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the UL transmission, processor  422  may perform a PUCCH transmission with OCC applied to a PUCCH format to support multiplexing. In some implementations, in performing the PUCCH transmission with the OCC applied to the PUCCH format to support multiplexing, processor  422  may perform the PUCCH transmission with the OCC applied to PUCCH format 2 or format 3 to support multiplexing by CDM. In such cases, a length of the OCC may be 2 or 4. 
     Illustrative Processes 
       FIG.  5    illustrates an example process  500  in accordance with an implementation of the present disclosure. Process  500  may be an example implementation of the proposed schemes described above with respect to UL designs for NR-U operation in mobile communications in accordance with the present disclosure. Process  500  may represent an aspect of implementation of features of apparatus  410  and apparatus  420 . Process  500  may include one or more operations, actions, or functions as illustrated by one or more of blocks  510 ,  520  and  530 . Although illustrated as discrete blocks, various blocks of process  500  may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Moreover, the blocks of process  500  may executed in the order shown in  FIG.  5    or, alternatively, in a different order. Process  500  may also be repeated partially or entirely. Process  500  may be implemented by apparatus  410 , apparatus  420  and/or any suitable wireless communication device, UE, roadside unit (RUS), base station or machine type devices. Solely for illustrative purposes and without limitation, process  500  is described below in the context of apparatus  410  as one UE (e.g., first UE  110 ) and apparatus  420  as another UE (e.g., second UE  120 ) in a network environment (e.g., network environment  100 ). Process  500  may begin at block  510 . 
     At  510 , process  500  may involve processor  412  of apparatus  410  (as a UE) receiving, via transceiver  416 , from a network node (e.g., network node  130 ) a scheduling of a plurality of starting slots for an UL transmission by apparatus  410 . Process  500  may proceed from  510  to  520 . 
     At  520 , process  500  may involve processor  412  performing, via transceiver  416 , a listen-before-talk (LBT) procedure. Process  500  may proceed from  520  to  530 . 
     At  530 , process  500  may involve processor  412  performing, via transceiver  416 , the UL transmission with an initial slot of the UL transmission in one of the plurality of starting slots based on a result of the LBT procedure. 
     In some implementations, in performing the UL transmission with the initial slot of the UL transmission in one of the plurality of starting slots based on the result of the LBT procedure, process  500  may involve processor  412  performing certain operations. For instance, process  500  may involve processor  412  selecting a first starting slot of the plurality of starting slots to begin the UL transmission responsive to the result of the LBT procedure indicating no other transmission in the first starting slot. Moreover, process  500  may involve processor  412  selecting a second starting slot of the plurality of starting slots after the first starting slot to begin the UL transmission responsive to the result of the LBT procedure indicating at least one other transmission in the first starting slot. 
     In some implementations, the at least one other transmission may include a PRACH transmission by another apparatus (e.g., apparatus  420 ). 
     In some implementations, in performing the UL transmission, process  500  may involve processor  412  performing the UL transmission with an initial slot of the UL transmission preceded by a preamble. In some implementations, the preamble may be cell-specific with respect to a cell with which apparatus  410  is associated. In some implementations, the preamble may be configured by RMSI or RRC signaling from the network node. In some implementations, the preamble may indicate a duration of the UL transmission. Alternatively, or additionally, the preamble may indicate an identification of a serving cell. 
     In some implementations, in performing the LBT procedure, process  500  may involve processor  412  performing certain operations. For instance, process  500  may involve processor  412  detecting an existence of any preamble before performing the UL transmission. Based on a result of the detecting, process  500  may involve processor  412  performing the LBT procedure before the UL transmission in response to a preamble transmitted by one other apparatus being detected. Alternatively, process  500  may involve processor  412  skipping the LBT procedure before the UL transmission in response to no preamble being detected. In some implementations, the UL transmission may include a PRACH transmission, a PUSCH transmission, a PUCCH transmission, or a sounding reference signal (SRS) transmission. 
     In some implementations, in performing the LBT procedure, process  500  may involve processor  412  performing the LBT procedure based on the preamble transmitted by one other apparatus being detected plus on one or more of: (a) the detected preamble belonging to a same serving cell with which the apparatus is associated; and (b) the UL transmission being within a duration of one other UL transmission by the other apparatus as indicated in the preamble. In some implementations, the UL transmission may include a PRACH transmission. In such cases, the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the UL transmission, process  500  may involve processor  412  performing a PUCCH transmission with OCC applied to a PUCCH format to support multiplexing. In some implementations, in performing the PUCCH transmission with the OCC applied to the PUCCH format to support multiplexing, process  500  may involve processor  412  performing the PUCCH transmission with the OCC applied to PUCCH format 2 or format 3 to support multiplexing by CDM. In some implementations, a length of the OCC may be 2 or 4. 
       FIG.  6    illustrates an example process  600  in accordance with an implementation of the present disclosure. Process  600  may be an example implementation of the proposed schemes described above with respect to UL designs for NR-U operation in mobile communications in accordance with the present disclosure. Process  600  may represent an aspect of implementation of features of apparatus  410  and apparatus  420 . Process  600  may include one or more operations, actions, or functions as illustrated by one or more of blocks  610 ,  620  and  630 . Although illustrated as discrete blocks, various blocks of process  600  may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Moreover, the blocks of process  600  may executed in the order shown in  FIG.  6    or, alternatively, in a different order. Process  600  may also be repeated partially or entirely. Process  600  may be implemented by apparatus  410 , apparatus  420  and/or any suitable wireless communication device, UE, RUS, base station or machine type devices. Solely for illustrative purposes and without limitation, process  600  is described below in the context of apparatus  410  as one UE (e.g., first UE  110 ) and apparatus  420  as another UE (e.g., second UE  120 ) in a network environment (e.g., network environment  100 ). Process  600  may begin at block  610 . 
     At  610 , process  600  may involve processor  422  of apparatus  420  (as a UE) detecting, via transceiver  426 , an existence of any preamble transmitted by another apparatus (e.g., apparatus  410 ). Based on a result of the detecting, process  600  may proceed from  610  to either  620  or  630 . 
     At  620 , process  600  may involve processor  422  performing, via transceiver  426 , an LBT procedure followed by an UL transmission in response to a preamble transmitted by one other apparatus (e.g., apparatus  410 ) being detected. 
     At  630 , process  600  may involve processor  422  performing, via transceiver  426 , the UL transmission without first performing the LBT procedure in response to no preamble being detected. 
     In some implementations, the UL transmission may include a PRACH transmission. In such cases, the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the LBT procedure, process  600  may involve processor  422  performing the LBT procedure based on the preamble transmitted by one other apparatus being detected plus on one or more of: (a) the detected preamble belonging to a same serving cell with which the apparatus is associated; and (b) the UL transmission being within a duration of one other UL transmission by the other apparatus as indicated in the preamble. In such cases, the UL transmission may include a PRACH transmission, and the other UL transmission may include a PUSCH transmission, a PUCCH transmission, or an SRS transmission. 
     In some implementations, in performing the UL transmission, process  600  may involve processor  422  performing a PUCCH transmission with OCC applied to a PUCCH format to support multiplexing. In some implementations, in performing the PUCCH transmission with the OCC applied to the PUCCH format to support multiplexing, process  600  may involve processor  422  performing the PUCCH transmission with the OCC applied to PUCCH format 2 or format 3 to support multiplexing by CDM. In such cases, a length of the OCC may be 2 or 4. 
     Additional Notes 
     The herein-described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable”, to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components. 
     Further, with respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
     Moreover, it will be understood by those skilled in the art that, in general, terms used herein, and especially in the appended claims, e.g., bodies of the appended claims, are generally intended as “open” terms, e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc. It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to implementations containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an,” e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more;” the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number, e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations. Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention, e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc. In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention, e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc. It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
     From the foregoing, it will be appreciated that various implementations of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various implementations disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.