Patent Publication Number: US-2023133612-A1

Title: Sidelink interlace configuration

Description:
FIELD 
     The subject matter disclosed herein relates generally to wireless communications and more particularly relates to interlacing sidelink resources for operation in unlicensed (i.e., shared) spectrum. 
     BACKGROUND 
     In sidelink communication, a User Equipment (“UE”) is able to communicate directly with another UE and without relaying its messages via a wireless network. 
     BRIEF SUMMARY 
     Disclosed are procedures for configuring interlacing of sidelink resources for operation in shared spectrum. Said procedures may be implemented by apparatus, systems, methods, or computer program products. 
     One method of a User Equipment (“UE”) for interlacing sidelink resources includes receiving a resource pool configuration and receiving an interlacing configuration corresponding to the resource pool configuration. Here, the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration for an unlicensed sidelink carrier. Additionally, the interlacing configuration indicates: a) the number of frequency resources (e.g., subcarriers or Physical Resource Blocks (“PRBs”)) per interlace based on the subchannel size, b) the spacing between the interlace based on the subchannel size, c) the minimum amount of resource to be used for transmission in a resource pool, and d) the type/method of interlacing to be performed. The method includes transmitting a sidelink channel according to the interlacing configuration within the unlicensed sidelink carrier, where the sidelink channel comprises at least one of: a sidelink data channel and a sidelink control channel. 
     One method of a network entity for interlacing sidelink resources includes transmitting a resource pool configuration to a UE, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration for an unlicensed sidelink carrier. The method also includes transmitting an interlacing configuration corresponding to the resource pool configuration to the UE, where the interlacing configuration indicates: a) the number of subcarriers (or PRBs) per interlace based on the subchannel size, b) the spacing between the interlace based on the subchannel size, c) the minimum amount of resource to be used for transmission in a resource pool, and d) the type/method of interlacing to be performed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
         FIG.  1    is a block diagram illustrating one embodiment of a wireless communication system for interlacing sidelink resources; 
         FIG.  2 A  is a diagram illustrating one embodiment of configuring a resource pool (“RP”) interlacing scheme; 
         FIG.  2 B  is a diagram illustrating one embodiment of a resource pool for sidelink operation; 
         FIG.  3    is a diagram illustrating one embodiment of a first interlacing scheme for sidelink operation; 
         FIG.  4    is a diagram illustrating one embodiment of a second interlacing scheme for sidelink operation; 
         FIG.  5    is a diagram illustrating one embodiment of a third interlacing scheme for sidelink operation; 
         FIG.  6    is a diagram illustrating one embodiment of a fourth interlacing scheme for sidelink operation; 
         FIG.  7    is a diagram illustrating one embodiment of a fifth interlacing scheme for sidelink operation; 
         FIG.  8    is a diagram illustrating one embodiment of a sixth interlacing scheme for sidelink operation; 
         FIG.  9    is a diagram illustrating one embodiment of a seventh interlacing scheme for sidelink operation; 
         FIG.  10    is a diagram illustrating one embodiment of an eighth interlacing scheme for sidelink operation; 
         FIG.  11    is a diagram illustrating one embodiment of a ninth interlacing scheme for sidelink operation; 
         FIG.  12    is a diagram illustrating one embodiment of a tenth interlacing scheme for sidelink operation; 
         FIG.  13    is a diagram illustrating one embodiment of an eleventh interlacing scheme for sidelink operation; 
         FIG.  14    is a diagram illustrating one embodiment of a twelfth interlacing scheme for sidelink operation; 
         FIG.  15    is a diagram illustrating one embodiment of a thirteenth interlacing scheme for sidelink operation; 
         FIG.  16    is a diagram illustrating one embodiment of a fourteenth interlacing scheme for sidelink operation; 
         FIG.  17    is a diagram illustrating one embodiment of a fifteenth interlacing scheme for sidelink operation; 
         FIG.  18    is a block diagram illustrating one embodiment of a user equipment apparatus that may be used for interlacing sidelink resources; 
         FIG.  19    is a block diagram illustrating one embodiment of a network apparatus that may be used for interlacing sidelink resources; 
         FIG.  20    is a flowchart diagram illustrating one embodiment of a first method for interlacing sidelink resources; and 
         FIG.  21    is a flowchart diagram illustrating one embodiment of a second method for interlacing sidelink resources. 
     
    
    
     DETAILED DESCRIPTION 
     As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects. 
     For example, the disclosed embodiments may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. 
     Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code. 
     Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. 
     More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or Flash memory), a portable compact disc read-only memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object-oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the “C” programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (“LAN”), wireless LAN (“WLAN”), or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider (“ISP”)). 
     Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment. 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. 
     As used herein, a list with a conjunction of “and/or” includes any single item in the list or a combination of items in the list. For example, a list of A, B and/or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. As used herein, a list using the terminology “one or more of” includes any single item in the list or a combination of items in the list. For example, one or more of A, B and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. As used herein, a list using the terminology “one of” includes one and only one of any single item in the list. For example, “one of A, B and C” includes only A, only B or only C and excludes combinations of A, B and C. As used herein, “a member selected from the group consisting of A, B, and C,” includes one and only one of A, B, or C, and excludes combinations of A, B, and C.” As used herein, “a member selected from the group consisting of A, B, and C and combinations thereof” includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. 
     Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. This code may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart diagrams and/or block diagrams. 
     The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the flowchart diagrams and/or block diagrams. 
     The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart diagrams and/or block diagrams. 
     The call-flow diagrams, flowchart diagrams and/or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods, and program products according to various embodiments. In this regard, each block in the flowchart diagrams and/or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s). 
     It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures. 
     Although various arrow types and line types may be employed in the call-flow, flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code. 
     The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements. 
     Generally, the present disclosure describes systems, methods, and apparatus for interlacing sidelink resources. In certain embodiments, the methods may be performed using computer code embedded on a computer-readable medium. In certain embodiments, an apparatus or system may include a computer-readable medium containing computer-readable code which, when executed by a processor, causes the apparatus or system to perform at least a portion of the below described solutions. 
     Future wireless devices may support sidelink operation on unlicensed spectrum. For uplink/downlink operation over the unlicensed spectrum, e.g., for channels such as Physical Uplink Shared Channel (“PUSCH”), Physical Uplink Control Channel (“PUCCH”) format  2 , etc., transmissions are to meet the Power Spectrum Density (“PSD”) regulation and minimum channel occupancy requirement (e.g., 80%). To fulfill these regulations, interlacing schemes may be used in LTE-unlicensed and NR-unlicensed that interlace physical channels, e.g., PUSCH and PUCCH channels, at resource block level. 
     Regarding sidelink resource allocation, the minimum scheduling unit (i.e., defined by subchannel consisting of ‘N’ PRBs and ‘M’ subchannels) constitutes a resource pool. Each sidelink (“SL”) carrier contains one SL Bandwidth Part (“BWP”) which is then associated with multiple transmission (“Tx”) Resource pools containing different configuration of the subchannel sizes {n10, n12, n15, n20, n25, n50, n75, n100}. The minimum scheduling unit of subchannel for sidelink contradicts that of uplink which is based on Resource Block (“RB”) level scheduling unit and each resource pool in sidelink does not span across entire bandwidth (“BW”) or Listen-Before-Talk (“LBT”) subbands which is the requirement for minimum occupancy and PSD limit. 
     To meet the regulatory requirements of PSD and the minimum channel occupancy (80%), sidelink unlicensed operation requires interlacing of subchannels and/or resource pools. However, another challenge of sidelink unlicensed operation is that the UE is not expected to use the remaining PRBs (i.e., not large enough for a full subchannel) in Rel-16 sidelink design, which is problematic for unlicensed operation as it might not meet the minimum occupancy requirement. 
     To support sidelink operation in shared (i.e., unlicensed) spectrum, the below solutions describe mechanisms to meet the regulatory requirements of PSD and minimum channel occupancy. 
     According to a first solution, each sidelink resource pool is configured to occupy the minimum occupied bandwidth (e.g., 20 MHz BW) using an interlacing configuration. The number of frequency resources (i.e., subchannels or PRBs) per interlace is represented by N and the spacing between interlace is represented by M, where the values of M and N are configured per resource pool based on the configured subchannel size. In certain embodiments, the interlacing itself is implemented on a subchannel-wise basis. 
     According to a second solution, when more than one resource pool configured to occupy the minimum occupied bandwidth for e.g., 20 MHz then number of resource pool occupying the LBT subband of 20 MHz bandwidth could be interleaved such that each interleaved resource pool occupies the entire LBT sub-band. 
     According to a third solution, the sidelink subchannel may be defined using non-contiguous frequency resources based on an interleaving of PRBs (or PRB groups) within a resource pool, thereby spreading the subchannel across a resource pool (in frequency domain). 
     In some embodiments, interlacing restrictions may be applied considering remaining PRBs i.e., not large enough for a full subchannel thereby named as empty PRBs. In one embodiment, the remaining PRBs are allocate as empty PRBs which may be configured towards the middle/center of the resource pool. In another embodiment, the remaining PRBs are incorporated into one or more subchannels, such that the resource pool is configured with mixed subchannel sizes. 
     In some embodiments, interlacing restrictions may be applied considering larger subchannel sizes. In one embodiment, a UE is configured with minimum amount of resource (subchannel/PRB) to be used for transmission in a resource pool considering the minimum occupied bandwidth and PSD limit. In another embodiment, the UE is configured with PRB interlacing within and across subchannel. 
     In certain embodiments, a UE is configured with an interlacing scheme where frequency resources are allocated beginning from both edges of the resource pool and working towards the middle/center of the resource pool. In certain embodiments, the UE is configured with an interlacing scheme where frequency resources are allocated beginning from the lowest PRB/PRB group in each of the subchannel in a resource pool and, after finishing all subchannels, then allocating the second lowest PRB/PRB group in each subchannel in a resource pool. 
       FIG.  1    depicts a wireless communication system  100  for interlacing sidelink resources, according to embodiments of the disclosure. In one embodiment, the wireless communication system  100  includes at least one remote unit  105 , a radio access network (“RAN”)  120 , and a mobile core network  140 . The RAN  120  and the mobile core network  140  form a mobile communication network. The RAN  120  may be composed of a base unit  121  with which the remote unit  105  communicates using wireless communication links  123 . Even though a specific number of remote units  105 , base units  121 , wireless communication links  123 , RANs  120 , and mobile core networks  140  are depicted in  FIG.  1   , one of skill in the art will recognize that any number of remote units  105 , base units  121 , wireless communication links  123 , RANs  120 , and mobile core networks  140  may be included in the wireless communication system  100 . 
     In one implementation, the RAN  120  is compliant with the Fifth Generation (“5G”) system specified in the Third Generation Partnership Project (“3GPP”) specifications. For example, the RAN  120  may be a Next Generation Radio Access Network (“NG-RAN”), implementing New Radio (“NR”) Radio Access Technology (“RAT”) and/or Long-Term Evolution (“LTE”) RAT. In another example, the RAN  120  may include non-3GPP RAT (e.g., Wi-Fi® or Institute of Electrical and Electronics Engineers (“IEEE”) 802.11-family compliant WLAN). In another implementation, the RAN  120  is compliant with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system  100  may implement some other open or proprietary communication network, for example Worldwide Interoperability for Microwave Access (“WiMAX”) or IEEE 802.16-family standards, among other networks. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. 
     In one embodiment, the remote units  105  may include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), smart appliances (e.g., appliances connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), or the like. In some embodiments, the remote units  105  include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units  105  may be referred to as the UEs, subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, user terminals, wireless transmit/receive unit (“WTRU”), a device, or by other terminology used in the art. In various embodiments, the remote unit  105  includes a subscriber identity and/or identification module (“SIM”) and the mobile equipment (“ME”) providing mobile termination functions (e.g., radio transmission, handover, speech encoding and decoding, error detection and correction, signaling and access to the SIM). In certain embodiments, the remote unit  105  may include a terminal equipment (“TE”) and/or be embedded in an appliance or device (e.g., a computing device, as described above). 
     The remote units  105  may communicate directly with one or more of the base units  121  in the RAN  120  via uplink (“UL”) and downlink (“DL”) communication signals. Furthermore, the UL and DL communication signals may be carried over the wireless communication links  123 . Here, the RAN  120  is an intermediate network that provides the remote units  105  with access to the mobile core network  140 . 
     In some embodiments, the remote units  105  communicate with an application server  151  via a network connection with the mobile core network  140 . For example, an application  107  (e.g., web browser, media client, telephone and/or Voice-over-Internet-Protocol (“VoIP”) application) in a remote unit  105  may trigger the remote unit  105  to establish a protocol data unit (“PDU”) session (or other data connection) with the mobile core network  140  via the RAN  120 . The mobile core network  140  then relays traffic between the remote unit  105  and the application server  151  in the packet data network  150  using the PDU session. The PDU session represents a logical connection between the remote unit  105  and the User Plane Function (“UPF”)  141 . 
     In order to establish the PDU session (or Packet Data Network (“PDN”) connection), the remote unit  105  must be registered with the mobile core network  140  (also referred to as “attached to the mobile core network” in the context of a Fourth Generation (“4G”) system). Note that the remote unit  105  may establish one or more PDU sessions (or other data connections) with the mobile core network  140 . As such, the remote unit  105  may concurrently have at least one PDU session for communicating with the packet data network  150 . The remote unit  105  may establish additional PDU sessions for communicating with other data networks and/or other communication peers. 
     In the context of a 5G system (“5GS”), the term “PDU Session” refers to a data connection that provides end-to-end (“E2E”) user plane (“UP”) connectivity between the remote unit  105  and a specific Data Network (“DN”) through the UPF  141 . A PDU Session supports one or more Quality of Service (“QoS”) Flows. In certain embodiments, there may be a one-to-one mapping between a QoS Flow and a QoS profile, such that all packets belonging to a specific QoS Flow have the same 5G QoS Identifier (“5QI”). 
     In the context of a 4G/LTE system, such as the Evolved Packet System (“EPS”), a PDN connection (also referred to as EPS session) provides E2E UP connectivity between the remote unit and a PDN. The PDN connectivity procedure establishes an EPS Bearer, i.e., a tunnel between the remote unit  105  and a Packet Gateway (“PGW”, not shown) in the mobile core network  140 . In certain embodiments, there is a one-to-one mapping between an EPS Bearer and a QoS profile, such that all packets belonging to a specific EPS Bearer have the same QoS Class Identifier (“QCI”). 
     The base units  121  may be distributed over a geographic region. In certain embodiments, a base unit  121  may also be referred to as an access terminal, an access point, a base, a base station, a Node-B (“NB”), an Evolved Node B (abbreviated as eNodeB or “eNB,” also known as Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”) Node B), a 5G/NR Node B (“gNB”), a Home Node-B, a relay node, a RAN node, or by any other terminology used in the art. The base units  121  are generally part of a RAN, such as the RAN  120 , that may include one or more controllers communicably coupled to one or more corresponding base units  121 . These and other elements of radio access network are not illustrated but are well known generally by those having ordinary skill in the art. The base units  121  connect to the mobile core network  140  via the RAN  120 . 
     The base units  121  may serve a number of remote units  105  within a serving area, for example, a cell or a cell sector, via a wireless communication link  123 . The base units  121  may communicate directly with one or more of the remote units  105  via communication signals. Generally, the base units  121  transmit DL communication signals to serve the remote units  105  in the time, frequency, and/or spatial domain. Furthermore, the DL communication signals may be carried over the wireless communication links  123 . The wireless communication links  123  may be any suitable carrier in licensed or unlicensed radio spectrum. The wireless communication links  123  facilitate communication between one or more of the remote units  105  and/or one or more of the base units  121 . Note that during NR operation on unlicensed spectrum (referred to as “NR-U”), the base unit  121  and the remote unit  105  communicate over unlicensed (i.e., shared) radio spectrum. 
     In one embodiment, the mobile core network  140  is a 5G core (“5GC”) or an Evolved Packet Core (“EPC”), which may be coupled to a packet data network  150 , like the Internet and private data networks, among other data networks. A remote unit  105  may have a subscription or other account with the mobile core network  140 . In various embodiments, each mobile core network  140  belongs to a single mobile network operator (“MNO”) and/or Public Land Mobile Network (“PLMN”). The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. 
     The mobile core network  140  includes several network functions (“NFs”). As depicted, the mobile core network  140  includes at least one UPF  141 . The mobile core network  140  also includes multiple control plane (“CP”) functions including, but not limited to, an Access and Mobility Management Function (“AMF”)  143  that serves the RAN  120 , a Session Management Function (“SMF”)  145 , a Policy Control Function (“PCF”)  147 , a Unified Data Management function (“UDM”) and a User Data Repository (“UDR”, also referred to as “Unified Data Repository”). Although specific numbers and types of network functions are depicted in  FIG.  1   , one of skill in the art will recognize that any number and type of network functions may be included in the mobile core network  140 . 
     The UPF(s)  141  is/are responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU session for interconnecting Data Network (“DN”), in the 5G architecture. The AMF  143  is responsible for termination of Non-Access Stratum (“NAS”) signaling, NAS ciphering &amp; integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The SMF  145  is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) Internet Protocol (“IP”) address allocation &amp; management, DL data notification, and traffic steering configuration of the UPF  141  for proper traffic routing. 
     The PCF  147  is responsible for unified policy framework, providing policy rules to CP functions, access subscription information for policy decisions in UDR. The UDM is responsible for generation of Authentication and Key Agreement (“AKA”) credentials, user identification handling, access authorization, subscription management. The UDR is a repository of subscriber information and may be used to service a number of network functions. For example, the UDR may store subscription data, policy-related data, subscriber-related data that is permitted to be exposed to third party applications, and the like. In some embodiments, the UDM is co-located with the UDR, depicted as combined entity “UDM/UDR”  149 . 
     In various embodiments, the mobile core network  140  may also include a Network Repository Function (“NRF”) (which provides Network Function (“NF”) service registration and discovery, enabling NFs to identify appropriate services in one another and communicate with each other over Application Programming Interfaces (“APIs”)), a Network Exposure Function (“NEF”) (which is responsible for making network data and resources easily accessible to customers and network partners), an Authentication Server Function (“AUSF”), or other NFs defined for the Fifth Generation Core network (“5GC”). When present, the AUSF may act as an authentication server and/or authentication proxy, thereby allowing the AMF  143  to authenticate a remote unit  105 . In certain embodiments, the mobile core network  140  may include an authentication, authorization, and accounting (“AAA”) server. 
     In various embodiments, the mobile core network  140  supports different types of mobile data connections and different types of network slices, wherein each mobile data connection utilizes a specific network slice. Here, a “network slice” refers to a portion of the mobile core network  140  optimized for a certain traffic type or communication service. For example, one or more network slices may be optimized for enhanced mobile broadband (“eMBB”) service. As another example, one or more network slices may be optimized for ultra-reliable low-latency communication (“URLLC”) service. In other examples, a network slice may be optimized for machine-type communication (“MTC”) service, massive MTC (“mMTC”) service, Internet-of-Things (“IoT”) service. In yet other examples, a network slice may be deployed for a specific application service, a vertical service, a specific use case, etc. 
     A network slice instance may be identified by a single-network slice selection assistance information (“S-NSSAI”) while a set of network slices for which the remote unit  105  is authorized to use is identified by network slice selection assistance information (“NSSAI”). Here, “NSSAI” refers to a vector value including one or more S-NSSAI values. In certain embodiments, the various network slices may include separate instances of network functions, such as the SMF  145  and UPF  141 . In some embodiments, the different network slices may share some common network functions, such as the AMF  143 . The different network slices are not shown in  FIG.  1    for ease of illustration, but their support is assumed. 
     While  FIG.  1    depicts components of a 5G RAN and a 5G core network, the described embodiments for interlacing sidelink resources apply to other types of communication networks and RATs, including IEEE 802.11 variants, Global System for Mobile Communications (“GSM”, i.e., a 2G digital cellular network), General Packet Radio Service (“GPRS”), Universal Mobile Telecommunications System (“UMTS”), LTE variants, CDMA 2000, Bluetooth, ZigBee, Sigfox, and the like. 
     Moreover, in an LTE variant where the mobile core network  140  is an EPC, the depicted network functions may be replaced with appropriate EPC entities, such as a Mobility Management Entity (“MME”), a Serving Gateway (“SGW”), a PGW, a Home Subscriber Server (“HSS”), and the like. For example, the AMF  143  may be mapped to an MME, the SMF  145  may be mapped to a control plane portion of a PGW and/or to an MME, the UPF  141  may be mapped to an SGW and a user plane portion of the PGW, the UDM/UDR  149  may be mapped to an HSS, etc. 
     In various embodiments, the remote units  105  may communicate directly with each other (e.g., device-to-device communication) using sidelink communication signals  115 . Here, sidelink transmissions may occur on sidelink resources. As discussed above, a remote unit  105  may be provided with different sidelink communication resources for different allocation modes. Mode-1 corresponds to a NR-based network-scheduled sidelink communication mode, wherein the in-coverage RAN  120  indicates resources for use in sidelink operation, including resources of one or more resource pools. Mode-2 corresponds to a NR-based UE-scheduled sidelink communication mode (i.e., UE-autonomous selection), where the remote unit  105  select a resource pools and resources therein from a set of candidate pools. Mode-3 corresponds to an LTE-based network-scheduled sidelink communication mode. Mode-4 corresponds to an LTE-based UE-scheduled sidelink communication mode (i.e., UE-autonomous selection). 
     In the following descriptions, the term “RAN node” is used for the base station/base unit, but it is replaceable by any other radio access node, e.g., gNB, ng-eNB, eNB, Base Station (“BS”), Access Point (“AP”), etc. Additionally, the term “UE” is used for the mobile station/remote unit, but it is replaceable by any other remote device, e.g., remote unit, MS, ME, etc. Further, the operations are described mainly in the context of 5G NR. However, the below described solutions/methods are also equally applicable to other mobile communication systems for interlacing sidelink resources. 
       FIG.  2 A  depicts a procedure  200  for configuring a resource pool interlacing scheme for sidelink operation in shared spectrum, according to embodiments of the disclosure. The procedure  200  involves a UE  205  and a RAN node  210  in a mobile communication network. Here, the UE  205  may be an embodiment of the remote unit  105 , while the RAN node  210  may be an embodiment of the base unit  121 . 
     At Step  1 , the UE  205  receives a resource pool configuration, e.g., from the RAN node  210  (see messaging  215 ). Here, the resource pool configuration indicates at least a subchannel size and a time-frequency configuration for the resource pool. In one embodiment, the resource pool configuration may include a bitmap of time slots and frequency resources corresponding to the resource pool. 
     As used herein, a “resource pool” refers to a set of resources assigned for sidelink operation. A resource pool consists of a set of resource blocks (i.e., Physical Resource Blocks (“PRB”)) over one or more time units (e.g., subframe, slots, Orthogonal Frequency Division Multiplexing (“OFDM”) symbols). In some embodiments, the set of resource blocks comprises contiguous PRBs in the frequency domain. As used herein, a PRB refers to twelve consecutive subcarriers in the frequency domain. In certain embodiments, a UE may be configured with separate transmission resource pools (“Tx RPs”) and reception resource pools (“Rx RPs”), where the Tx RP of one UE is associated with an Rx RP of another UE (i.e., peer UE) to enable sidelink communication. 
     At Step  2 , the UE  205  receives an interlacing configuration corresponding to the resource pool configuration (see messaging  220 ). In various embodiments, the interlacing configuration indicates a number of frequency resources per interlace (denoted using parameter ‘N’) and a spacing between each interlace (denoted using parameter ‘M’). As noted above, the values of M and N are based on the subchannel size indicated in the resource pool configuration. Additionally, the interlacing configuration indicates a minimum amount of (frequency) resources to be used for transmission in a resource pool and a type (or method) of interlacing to be used (e.g., subchannel interlacing, PRB interleaving, subchannel interleaving, etc.). 
     At Step  3 , the UE  205  determines an interlacing scheme for one or more resource pools based on the received configurations (see block  225 ). In one embodiment, the UE  205  applies the interlacing configuration to the resource pool configuration to derive the particular interlacing scheme to use on the unlicensed sidelink carrier. 
     At Step  4 , the UE  205  transmits sidelink data in a resource pool to a peer UE on an unlicensed (i.e., shared spectrum) sidelink carrier, following the determined interlacing scheme (see messaging  230 ). 
     While  FIG.  2 A  depicts the UE  205  receiving the resource pool configuration from the network (i.e., from the RAN node  210 ), in other embodiments the resource pool configuration may be pre-configured in the UE  205 . 
       FIG.  2 B  depicts one example of a Resource Pool  250  for sidelink communication, according to embodiments of the disclosure. Each SL carrier contains one SL BWP which is then associated with multiple Tx Resource pools containing different configuration of the subchannel sizes, i.e., {n10, n12, n15, n20, n25, n50, n75, n100}. A resource pool structure (pre)configuration contains subchannel size and bitmap of time slot and frequency resource. 
     Regarding the subchannel size configuration for a resource pool, for the number of PRBs for resource pool, a SL BWP may configure all the number of PRBs. In certain embodiments, the configured PRBs for a resource pool is not a multiple of subchannel size such that there is a set of remaining PRBs that is too small to form a subchannel of the configured subchannel size. In one embodiment, the remaining PRBs may be allocated as empty (i.e., zero-power) PRBs located at or near the resource pool center frequency. In another embodiment, the resource pool is configured with mixed subchannel size, such that the “remaining” PRBs are assigned to one or more subchannels. 
     Described herein are solutions for sidelink operation over the unlicensed spectrum that meets regulatory requirements, e.g., of Power Spectrum Density (“PSD”) and the minimum channel occupancy (80%) regulations. In various embodiments, the UE is configured with a resource pool interlacing scheme to occupy minimum occupied bandwidth, minimum subchannel size(s) allocation to a UE for transmission could cover the minimum occupied bandwidth, subchannel wise interlacing and doing both subchannel and resource pool wise interlacing, restriction on configuring interlacing, especially considering larger subcarrier spacing (“SC S”) values and larger subchannel sizes. 
     According to embodiments of the first solution, each Resource Pool (“RP”) is configured to occupy the minimum occupied bandwidth (e.g., 20 MHz bandwidth) and interlacing is performed on a subchannel-wise basis. 
     In various embodiments, the interlacing structure design (i.e., interlacing scheme) for sidelink defines the number of subchannels per interlace (N) and the spacing between the interlace (M), where the values of (N) and (M) vary depending on the subchannel size. As noted above, the interlacing structure design may be (pre)configured per resource pool. Alternatively, the interlacing structure design may be configured by the network. In certain embodiments, the subchannel size of a resource pool is (pre)configured per resource pool. 
     In some embodiments, there may be configuration restrictions while configuring the interlacing structure for a resource pool considering larger subchannel size(s) such as 50, 75, 100 PRBs to satisfy the minimum occupancy bandwidth. 
     In one implementation, the UE  205  may be configured to transmit in a minimum number of PRBs considering one or more subchannels configured in a resource pool, where the minimum number of PRBs satisfies the minimum occupancy requirement (e.g., 80%) and PSD limit. In some embodiments, the minimum number of PRBs for transmission in a resource pool is configured (or pre-configured) per resource pool. In certain embodiments, the size of a transport block (“TB”) containing sidelink data may be less than the subchannel size. In such embodiments, the UE  205  may repeat the same TB in different PRBs in same or different subchannels in order to cover the minimum number of occupied bandwidths. 
     In another implementation, the interlacing structure design defines PRB-level interlacing within a subchannel. In some embodiments, the parameter indicating the number of PRBs per interlace (denoted N′) and the spacing between the interlaces (denoted M′) may be configured (or pre-configured) for that subchannel in a resource pool. 
       FIG.  3    depicts an example interlacing structure design  300  with PRB-level interlacing across a subchannel, according to embodiments of the disclosure. In some embodiments, when there is only one subchannel within the LBT sub-band then the interlacing is performed within that subchannel. It is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz. As depicted, the interlacing structure comprises one PRB in ten, for example PRBs #0, #10, #20, #30, #40, #50, #60, #70, #80, and #90. For the depicted example, N′=10, M′=10, and the starting PRB index=0. 
       FIG.  4    depicts another example interlacing structure design  400  with PRB-level interlacing across a subchannel, according to embodiments of the disclosure. In some embodiments, when there are more than one subchannels within the LBT sub-band, then the interlacing is performed across more than one subchannels to satisfy the minimum occupied bandwidth criteria. It is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz. Here, the first subchannel comprises at least PRB index #0 to PRB index #20 and the second subchannel comprises at least PRB index #80 to PRB index #99. In one embodiment, the first and second subchannels are of equal size. In another embodiment, the first and second subchannels are of different sizes. As depicted, the interlacing structure comprises one PRB in ten, for example PRBs #0, #10, #20, #30, #40, #50, #60, #70, #80, and #90. For the depicted example, N′=10, M′=10, and the starting PRB index=0. 
     In another implementation, the interlacing structure design may be interlaced subchannel-wise such that the UE  205  starts allocating resources from both edges of a resource pool, i.e., from the start of the subchannel in the resource pool (i.e., lowest subchannel (“SC”) index), then followed by allocating resource towards end of the subchannel in a resource pool, and finally the remaining allocation could be in the middle/center subchannel in a resource pool. In another example, the UE  205  may begin allocation PRB-wise from both edges of the PRBs in a subchannel and finally from the middle/center PRBs in a subchannel. 
       FIG.  5    depicts another example interlacing structure design  500  with subchannel-level interlacing across a resource pool, according to embodiments of the disclosure. Here, it is assumed that the resource pool is comprises of at least seven subchannels. The subchannels may be of equal size or may be of different sizes, e.g., according to the principles described below. In the depicted embodiments, the interlacing structure comprises the lowest subchannel index (e.g., SC #1), the highest subchannel index (e.g., SC #7), and at least one subchannel in the middle of the resource pool (e.g., SC #4). 
     In another implementation, interlacing structure design may be interlaced such that UE  205  starts allocation with the lowest PRB (or PRB group) in each of the subchannel in a resource pool and, after finishing all subchannel, then allocating the second lowest PRB/PRB group in each subchannel in a resource pool. In one example, the first interlace is formed from the lowest PRB/PRB group from each subchannel, the second interlace is formed from the second lowest PRB/PRB group from each subchannel, and so on. In certain embodiments, a PRB group is added as a parameter in the Radio Resource Control (“RRC”) resource pool (pre)configuration. 
     Turning again to  FIG.  4   , the first interlace (i.e., Interlace #0) comprises PRB indices: #0, #10, #20, #30, #40, #50, #60, #70, #80, and #90, while the second interlace (i.e., Interlace #1) comprises PRB indices: #1, #11, #21, #31, #41, #51, #61, #71, #81, and #91, and so forth. 
     In some embodiments, the UE  205  is not expected to use the remaining PRBs (i.e., those not large enough for a full subchannel) if the configured PRBs for resource pool is not a multiple of subchannel size. These unused remaining PRBs become empty PRBs; however, not utilizing those empty PRBs may cause problem with the satisfying the minimum occupied bandwidth requirement for the unlicensed sidelink operation. 
     According to a first option, a resource pool may be configured with the empty PRBs in the middle/center of the resource pool. In certain embodiments, a parameter is introduced as part of the resource pool (pre)configuration in RRC indicating the bitmap of the PRBs (or PRB group(s)) belonging to the empty PRBs. 
       FIG.  6    depicts an example interlacing structure design  600  with empty PRBs in the middle/center of the resource pool, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into eight (8) subchannels of equal size (i.e., 12 PRBs). However, because the configured PRBs for the resource pool (i.e., 100 PRBs) is not a multiple of subchannel size (i.e., 12 PRBs), there is a set of remaining PRBs (i.e., 4 PRBs) that is too small to form a subchannel of the configured subchannel size. Accordingly, the interlacing structure design  600  is configured with the four middle-most PRBs (i.e., PRB indices #48 to #51) as empty PRBs. For the depicted example, M=2 and N=4, with PRB indices #48 to #51 being empty. 
       FIG.  7    depicts another example interlacing structure design  700  with empty PRBs in the middle/center of the resource pool, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into six (6) subchannels of equal size (i.e., 15 PRBs). However, because the configured PRBs for the resource pool (i.e., 100 PRBs) is not a multiple of subchannel size (i.e., 15 PRBs), there is a set of remaining PRBs (i.e., 10 PRBs) that is too small to form a subchannel of the configured subchannel size. Accordingly, the interlacing structure design  700  is configured with the ten middle-most PRBs (i.e., PRB indices #45 to #54) as empty PRBs. For the depicted example, M=2 and N=3, with PRB indices #45 to #55 being empty. 
       FIG.  8    depicts a further example interlacing structure design  800  with empty PRBs in the middle/center of the resource pool, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into a single, distributed subchannel of size smaller than the LBT sub-band. In the depicted example, the single subchannel is of size 75 PRBs, therefore there is a set of 25 remaining PRBs that is too small to form a subchannel of the configured subchannel size. Accordingly, the interlacing structure design  600  is configured with the 25 middle-most PRBs (i.e., PRB indices #37 to #61) as empty PRBs. 
     According to a second option, the resource pool may be configured with more than one subchannel sizes (i.e., a resource pool with the mixed subchannel sizes). In certain embodiments, a bitmap is added in the RRC resource pool (pre)configuration, the new bitmap containing subchannel number from the lowest subchannel to the highest subchannel for each subchannel size. 
       FIG.  9    depicts an example interlacing structure design  900  with mixed subchannel sizes, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into eight (8) subchannels of mixed size. For this resource pool configuration, the default subchannel size is 12 PRBs. However, because the configured PRBs for the resource pool (i.e., 100 PRBs) is not a multiple of the default subchannel size (i.e., 12 PRBs), there is a set of remaining PRBs (i.e., 4 PRBs) that is too small to form a subchannel of the configured subchannel size. 
     Accordingly, the interlacing structure design  900  is configured with mixed subcarrier size such that the two lowest subchannels (i.e., SC #0 and SC #1) and the two highest subchannels (i.e., SC #6 and SC #7) are each allocated an extra PRB, thereby forming subchannels of size 13 PRBs. In an alternative configuration, the lowest subchannel (i.e., SC #0) and the highest subchannel (i.e., SC #7) are each allocated two extra PRBs, thereby forming subchannels of size 14 PRBs. Note that the interlacing configuration may indicate the size and locations of the larger subchannels (i.e., having non-default size) or, alternatively, of the size and locations of the smaller subchannels. 
       FIG.  10    depicts an example interlacing structure design  1000  with mixed subchannel sizes, according to embodiments of the disclosure. Here, is assumed that the resource pool is divided into six (8) subchannels of mixed size. In one embodiment, the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz. For this resource pool configuration, the default subchannel size is 20 PRBs. Although the configured PRBs for the resource pool (i.e., 100 PRBs) is a multiple of the default subchannel size (i.e., 20 PRBs), one subchannel/group of 20 PRBs is split into two subchannels of size 10 PRBs to distribute frequency resources more evenly during subchannel-level interlacing. 
     In another embodiment, the LBT sub-band spans 50 PRBs (i.e., from PRB index #0 to PRB index #49) with SCS=30 kHz. For this resource pool configuration, the default subchannel size is 10 PRBs. Although the configured PRBs for the resource pool (i.e., 50 PRBs) is a multiple of the default subchannel size (i.e., 10 PRBs), one subchannel/group of 10 PRBs is split into two subchannels of size 5 PRBs to distribute frequency resources more evenly during subchannel-level interlacing. 
     Accordingly, the interlacing structure design  1000  is configured with mixed subcarrier size such that the two lowest subchannels (i.e., SC #0 and SC #1) and the two highest subchannels (i.e., SC #4 and SC #5) are the default size (i.e., 20 PRBs or 10 PRBs), while the two middle subchannels (i.e., SC #2 and SC #3) are the smaller size (i.e., 10 PRBs or 5 PRBs). Note that the interlacing configuration may indicate the size and locations of the smaller subchannels (i.e., having non-default size) or, alternatively, of the size and locations of the larger subchannels. 
     In some embodiments, the resource pool configuration uses smaller subchannel sizes (i.e., as compared to subchannel size defined in 3GPP Release 16) to benefit from evenly distributed of resources across the LBT sub-bands. For example, subchannel sizes of 4 and 5 for different sub-carrier spacing (e.g., 15 kHz and 30 kHz) may be introduced for interlacing structure designs supporting unlicensed sidelink operation. 
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing configuration for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 4, 5, 10 PRBs (i.e., smaller than the 3GPP Rel-16 subchannel size of 12 PRBs) for sub-carrier spacing of 15 kHz is shown in the below Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (100 PRBs@15 KHz SCS) 
               
            
           
           
               
               
               
            
               
                   
                 Number of 
                   
               
               
                 Subchannel 
                 subchannels in 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 15 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
            
               
                 4 
                 25 
                 M = 5, N = 5 
               
               
                   
                   
                 Interlace #0 = SC #0, 5, 10, 15, 20 
               
               
                   
                   
                 Interlace #1 = SC #1, 6, 11, 16, 21 
               
               
                   
                   
                 Interlace #2 = SC #2, 7, 12, 17, 22 
               
               
                   
                   
                 Interlace #3 = SC #3, 8, 13, 18, 23 
               
               
                   
                   
                 Interlace #4 = SC #4, 9, 14, 19, 24 
               
               
                 5 
                 20 
                 M = 4, N = 5 
               
               
                   
                   
                 Interlace #0 = SC #0, 4, 8, 12, 16 
               
               
                   
                   
                 Interlace #1 = SC #1, 5, 9, 13, 17 
               
               
                   
                   
                 Interlace #2 = SC #2, 6, 10, 14, 18 
               
               
                   
                   
                 Interlace #3 = SC #3, 7, 11, 15, 19 
               
               
                 10 
                 10 
                 M = 2, N = 5 
               
               
                   
                   
                 Interlace 0 SC #0, 2, 4, 6, 8 
               
               
                   
                   
                 Interlace 1 SC #1, 3, 5, 7, 9 
               
               
                   
               
            
           
         
       
     
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing configuration for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 12, 15, 20, 25 PRBs for sub-carrier spacing of 15 kHz is shown in the below Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (100 PRBs@15 KHz SCS) 
               
            
           
           
               
               
               
               
            
               
                   
                 Number of 
                   
                   
               
               
                 Subchannel 
                 subchannels in 
                 Remaining 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 PRBs 
                 15 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 12 
                 8 
                 4 
                 Option 1: 
               
               
                   
                   
                   
                 M = 2, N = 4 and configure Middle/Center of RP with 4 
               
               
                   
                   
                   
                 empty PRBs as shown in the FIG. 6. 
               
               
                   
                   
                   
                 Interlace #0 = SC #0, 2, 4, 6 
               
               
                   
                   
                   
                 Interlace #1 = SC #1, 3, 5, 7 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 Remaining PRBs are allocated to one or more interlaces 
               
               
                   
                   
                   
                 for resource allocation as shown in FIG. 9. E.g., 
               
               
                   
                   
                   
                 SC #0, 1, 6, 7 can be configured with 13 PRBs each 
               
               
                   
                   
                   
                 Alt., SC #0, 7 can be configured with 14 PRBs each 
               
               
                 15 
                 6 
                 10 
                 Option 1: 
               
               
                   
                   
                   
                 M = 2, N = 3 and configure Middle/Center of RP with 10 
               
               
                   
                   
                   
                 empty PRBs as shown in the FIG. 7 
               
               
                   
                   
                   
                 Interlace #0 = SC #0, 2, 4 
               
               
                   
                   
                   
                 Interlace #1 = SC #1, 3, 5 
               
               
                 20 
                 5 
                 0 
                 Option 1: 
               
               
                   
                   
                   
                 M = 2, N = 3 where the one remaining subchannel of 20 
               
               
                   
                   
                   
                 PRBs can be split into two subchannel of 10 PRBs each, 
               
               
                   
                   
                   
                 with 6 subchannels with 4 SC having 20 PRBs each 
               
               
                   
                   
                   
                 and 2 SC having 10 RBs each as shown in FIG. 10. 
               
               
                   
                   
                   
                 Or 
               
               
                   
                   
                   
                 Interleave 20 into two parts of 10 PRBs or into four parts 
               
               
                   
                   
                   
                 of 5 PRBs and then use above allocation 
               
               
                 25 
                 4 
                 0 
                 Option 1: 
               
               
                   
                   
                   
                 M = 1, N = 4 
               
               
                   
                   
                   
                 Only one interlace 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured across 
               
               
                   
                   
                   
                 subchannel as shown in FIG. 11. Another example of 
               
               
                   
                   
                   
                 the interlacing configuration is UE may start allocation 
               
               
                   
                   
                   
                 with the lowest PRB/PRB group in each of the 
               
               
                   
                   
                   
                 subchannel in a resource pool and after finishing all 
               
               
                   
                   
                   
                 subchannel then the second lowest PRB/PRB group in 
               
               
                   
                   
                   
                 each subchannel in a resource pool. 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation 
               
               
                   
                   
                   
                 from both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                   
                   
                   
                 Or 
               
               
                   
                   
                   
                 same as above by dividing it into 5 parts of 5 PRBs 
               
               
                   
               
            
           
         
       
     
       FIG.  11    depicts an example interlacing structure design  1100  with PRB-level interlacing across multiple subchannels, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into four subchannels of equal size (i.e., 25 PRBs). As depicted, the interlacing structure extends across multiple subchannels. In one embodiment, a first interlace (i.e., Interlace #0) comprises PRB indices: #0, #10, #20, #30, #40, #50, #60, #70, #80, and #90, while the second interlace (i.e., Interlace #1) comprises PRB indices: #1, #11, #21, #31, #41, #51, #61, #71, #81, and #91, and so forth. For the depicted example, N′=10 and M′=10. 
       FIG.  12    depicts an example interlacing structure design  1200  with PRB-level interlacing across multiple subchannels, according to embodiments of the disclosure. Here, is assumed that the LBT sub-band spans 100 PRBs (i.e., from PRB index #0 to PRB index #99) with SCS=15 kHz and the resource pool is divided into two subchannels of equal size (i.e., 50 PRBs). As depicted, the interlacing structure extends across multiple subchannels. In one embodiment, a first interlace (i.e., Interlace #0) comprises PRB indices: #0, #10, #20, #30, #40, #50, #60, #70, #80, and #90, while the second interlace (i.e., Interlace #1) comprises PRB indices: #1, #11, #21, #31, #41, #51, #61, #71, #81, and #91, and so forth. For the depicted example, N′=10 and M′=10. 
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing configuration for a resource pool configured with a 20 MHz bandwidth considering larger subchannel sizes from 50, 75, and 100 PRBs for sub-carrier spacing of 15 kHz is shown in the below Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (100 PRBs@15 KHz SCS) 
               
            
           
           
               
               
               
               
            
               
                   
                 Number of 
                   
                   
               
               
                 Subchannel 
                 subchannels in 
                 Remaining 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 PRBs 
                 15 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 50 
                 2 
                 0 
                 Option 1: 
               
               
                   
                   
                   
                 M = 1, N = 2 
               
               
                   
                   
                   
                 Only one interlace 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured across 
               
               
                   
                   
                   
                 subchannel as shown in FIG. 12. Another example of the 
               
               
                   
                   
                   
                 interlacing configuration is UE may start allocation with the 
               
               
                   
                   
                   
                 lowest PRB/PRB group in each of the subchannel in a 
               
               
                   
                   
                   
                 resource pool and after finishing all subchannel then the 
               
               
                   
                   
                   
                 second lowest PRB/PRB group in each subchannel in a 
               
               
                   
                   
                   
                 resource pool. 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation from 
               
               
                   
                   
                   
                 both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                 75 
                 1 
                 25 
                 Option1: 
               
               
                   
                   
                   
                 One subchannel with 25 empty PRBs in the middle/center, 
               
               
                   
                   
                   
                 whereas the SC#0 is distributed as shown in FIG. 8. 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 Remaining 25 PRBs may be configured as a SC#1. 
               
               
                   
                   
                   
                 SC#0: 75 PRBs (distributed) 
               
               
                   
                   
                   
                 SC#1: 25 PRBs 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured in a 
               
               
                   
                   
                   
                 subchannel 
               
               
                   
                   
                   
                 Option 4: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation from 
               
               
                   
                   
                   
                 both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                 100 
                 1 
                 0 
                 Option 1: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured in a 
               
               
                   
                   
                   
                 subchannel 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation from 
               
               
                   
                   
                   
                 both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool 
               
               
                   
               
            
           
         
       
     
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing structure for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 4, 5, 10, 12 for sub-carrier spacing of 30 kHz is shown in the below Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (50 PRBs@30 KHz SCS) 
               
            
           
           
               
               
               
               
            
               
                   
                 Number of 
                   
                   
               
               
                 Subchannel 
                 subchannels in 
                 Remaining 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 PRBs 
                 30 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 4 
                 12 
                 2 
                 M = 2, N = 6 
               
               
                   
                   
                   
                 Interlace 0 SC #0, 2, 4, 6, 8, 10 
               
               
                   
                   
                   
                 Interlace 1 SC #1, 3, 5, 7, 9, 11 
               
               
                   
                   
                   
                 2 empty PRBs in the middle/center of the resource pool 
               
               
                 5 
                 10 
                 0 
                 M = 2, N = 5 
               
               
                   
                   
                   
                 Interlace 0 SC #0, 2, 4, 6, 8 
               
               
                   
                   
                   
                 Interlace 1 SC #1, 3, 5, 7, 9 
               
               
                 10 
                 5 
                 0 
                 M = 2, N = 3 where the one remaining subchannel of 20 
               
               
                   
                   
                   
                 PRBs can be split into two subchannel of 10 PRBs each, 
               
               
                   
                   
                   
                 with 6 subchannels with 4 SC having 20 RBs each and 2 
               
               
                   
                   
                   
                 SC having 10 RBs each 
               
               
                 12 
                 4 
                 2 
                 Option 1: 
               
               
                   
                   
                   
                 M = 1, N = 4 
               
               
                   
                   
                   
                 Only one interlace 
               
               
                   
                   
                   
                 2 empty PRBs allocated in the middle/center of the 
               
               
                   
                   
                   
                 resource pool 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured across 
               
               
                   
                   
                   
                 subchannel. Another example of the interlacing 
               
               
                   
                   
                   
                 configuration is UE may start allocation with the lowest 
               
               
                   
                   
                   
                 PRB/PRB group in each of the subchannel in a resource 
               
               
                   
                   
                   
                 pool and after finishing all subchannel then the second 
               
               
                   
                   
                   
                 lowest PRB/PRB group in each subchannel in a resource 
               
               
                   
                   
                   
                 pool. 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation 
               
               
                   
                   
                   
                 from both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                   
               
            
           
         
       
     
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing structure for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 15, 20 for sub-carrier spacing of 30 kHz is shown in the below Table 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (50 PRBs@30 KHz SCS) 
               
            
           
           
               
               
               
               
            
               
                   
                 Number of 
                   
                   
               
               
                 Subchannel 
                 subchannels in 
                 Remaining 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 PRBs 
                 30 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 15 
                 3 
                 5 
                 Option 1: 
               
               
                   
                   
                   
                 M = 1, N = 3 
               
               
                   
                   
                   
                 Only one interlace 
               
               
                   
                   
                   
                 5 empty PRBs allocated in the middle/center of the 
               
               
                   
                   
                   
                 resource pool 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured across 
               
               
                   
                   
                   
                 subchannel. Another example of the interlacing 
               
               
                   
                   
                   
                 configuration is UE may start allocation with the lowest 
               
               
                   
                   
                   
                 PRB/PRB group in each of the subchannel in a resource 
               
               
                   
                   
                   
                 pool and after finishing all subchannel then the second 
               
               
                   
                   
                   
                 lowest PRB/PRB group in each subchannel in a resource 
               
               
                   
                   
                   
                 pool. 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation 
               
               
                   
                   
                   
                 from both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                 20 
                 2 
                 10 
                 Option 1: 
               
               
                   
                   
                   
                 M = 1, N = 2 where the one remaining 10 PRBs can be 
               
               
                   
                   
                   
                 left empty in the middle/center of the resource pool 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 M = 1, N = 2 where the one remaining 10 PRBs can be 
               
               
                   
                   
                   
                 split into two subchannel of 5 PRBs each, as shown in 
               
               
                   
                   
                   
                 FIG. 10. 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 PRB/PRB group level interlacing configured across 
               
               
                   
                   
                   
                 subchannel. Another example of the interlacing 
               
               
                   
                   
                   
                 configuration is UE may start allocation with the lowest 
               
               
                   
                   
                   
                 PRB/PRB group in each of the subchannel in a resource 
               
               
                   
                   
                   
                 pool and after finishing all subchannel then the second 
               
               
                   
                   
                   
                 lowest PRB/PRB group in each subchannel in a resource 
               
               
                   
                   
                   
                 pool. 
               
               
                   
                   
                   
                 Option 3: 
               
               
                   
                   
                   
                 UE may start PRB/PRB group/subchannel allocation 
               
               
                   
                   
                   
                 from both edge of the resource pool and then from the 
               
               
                   
                   
                   
                 middle/center of the resource pool. 
               
               
                   
               
            
           
         
       
     
     Considering the above options for the sidelink unlicensed operation, an exemplary example of interlacing structure for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 25, 50 for sub-carrier spacing of 30 kHz is shown in the below Table 6. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for a resource 
               
               
                 pool with 20 MHz BW (50 PRBs@30 KHz SCS) 
               
            
           
           
               
               
               
            
               
                   
                 Number of 
                   
               
               
                 Subchannel 
                 subchannels in a 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 resource pool 
                 30 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
            
               
                 25 
                 2 
                 Option 1: 
               
               
                   
                   
                 M = 1, N = 2 containing one interlace configuration 
               
               
                   
                   
                 Option 2: 
               
               
                   
                   
                 PRB/PRB group level interlacing configured across subchannel. 
               
               
                   
                   
                 Another example of the interlacing configuration is UE may start 
               
               
                   
                   
                 allocation with the lowest PRB/PRB group in each of the 
               
               
                   
                   
                 subchannel in a resource pool and after finishing all subchannel 
               
               
                   
                   
                 then the second lowest PRB/PRB group in each subchannel in a 
               
               
                   
                   
                 resource pool. 
               
               
                   
                   
                 Option 3: 
               
               
                   
                   
                 UE may start PRB/PRB group/subchannel allocation from both 
               
               
                   
                   
                 edge of the resource pool and then from the middle/center of the 
               
               
                   
                   
                 resource pool. 
               
               
                 50 
                 1 
                 Option 1: 
               
               
                   
                   
                 PRB/PRB group level interlacing configured across subchannel. 
               
               
                   
                   
                 Another example of the interlacing configuration is UE may start 
               
               
                   
                   
                 allocation with the lowest PRB/PRB group in each of the 
               
               
                   
                   
                 subchannel in a resource pool and after finishing all subchannel 
               
               
                   
                   
                 then the second lowest PRB/PRB group in each subchannel in a 
               
               
                   
                   
                 resource pool. 
               
               
                   
                   
                 Option 2: 
               
               
                   
                   
                 UE may start PRB/PRB group/subchannel allocation from both 
               
               
                   
                   
                 edge of the resource pool and then from the middle/center of the 
               
               
                   
                   
                 resource pool. 
               
               
                   
               
            
           
         
       
     
     According to embodiments of: More than one resource pool configured to occupy the minimum occupied bandwidth (e.g., 20 MHz BW), interleaving is performed among frequency resources (e.g., subchannels, or PRBs, or PRB groups) in addition to the interlacing. In various embodiments, when more than one resource pool is configured to occupy the minimum occupied bandwidth (e.g., for 20 MHz) then the number of resource pool occupying the 20 MHz bandwidth may be interleaved, such that each interleaved resource pool occupies the entire LBT sub-band. 
       FIG.  13    depicts an example interlacing structure design  1300  with resource pool interleaving, e.g., at the subchannel level, is performed across a LBT sub-band, according to embodiments of the disclosure. In some embodiments, when more than one resource pool is configured to occupy the minimum occupied bandwidth then subchannels of a first resource pool are interleaved with subchannels of a second resource pool, such that each interleaved resource pool occupies the entire LBT sub-band. It is assumed that the LBT sub-band spans 20 MHz with SCS=15 kHz. As depicted, the interlacing structure comprises six (6) subchannels of the first resource pool (denoted RP #0) interleaved with six (6) subchannels of the second resource pool (denoted RP #1). 
     In some embodiments, an interleaving parameter  1 ′ could be configured such that L=0 means there is no interleaving configured and L=1 means two resource pool may be interleaved in the frequency domain, i.e., alternating between subchannel of first resource pool and subchannel of the second resource pool and so on as shown in the  FIG.  13   . 
     When more than one resource pool overlaps in the frequency domain and when these resource pool bandwidths are the same, then the same or similar subchannel size configurations may be applied for these overlapping resource pool. For example, within a 20 MHz of LBT sub-band when there are two configured resource pools with 20 MHz and 10 MHz each and there is a 10 MHz of frequency overlapping between them, then the sub-channel size configuration for these resource pool maybe configured as same/similar, i.e., 5 PRB of subchannel size. 
     In various embodiments of the second solution, subchannel-wise interlacing (e.g., as described above in the first solution) may be performed within each resource pool, in addition to the interleaving of the resource pools, such that the UE  205  occupies the minimum occupied bandwidth while performing transmission within the resource pool. 
     In some implementations of the second solution, resource pool interleaving may be performed even when resource pool bandwidth configuration and subchannel sizes of each resource pool are different. In such embodiments, the interleaving configuration may be chosen such that each of these resource pools satisfies the minimum occupied bandwidth requirement. 
       FIG.  14    depicts an example interlacing structure design  1400  with resource pool interleaving, e.g., at the subchannel level, is performed across a LBT sub-band, according to embodiments of the disclosure. Here, the interleaving parameter ‘L’ has a value L=1 such that subchannels of a first resource pool are interleaved with subchannels of a second resource pool, such that each interleaved resource pool occupies the entire LBT sub-band. It is assumed that the LBT sub-band spans 20 MHz with SCS=15 kHz. As depicted, the interlacing structure comprises six (6) subchannels of the first resource pool (denoted RP #0) interleaved with six (6) subchannels of the second resource pool (denoted RP #1). However, the first resource pool is configured with a larger subchannel size than the second resource pool. 
       FIG.  15    depicts an example interlacing structure design  1500  with resource pool interleaving, e.g., at the subchannel level, is performed across a LBT sub-band, according to embodiments of the disclosure. In the depicted embodiment, the first resource pool (denoted RP #0) is configured with a larger number of subchannels than the second resource pool (denoted RP #1). Accordingly, the interlacing structure comprises eight (8) subchannels of the first resource pool (denoted RP #0) interleaved with four (4) subchannels of the second resource pool (denoted RP #1), such that each interleaved resource pool occupies the entire LBT sub-band. 
     Because more than one resource pool may be configured to occupy the minimum occupied bandwidth (e.g., 20 MHz BW) and each of the resource pool might not contain multiple of configured subchannel size, then the remaining PRB from each of the resource pools occupying the minimum occupied bandwidth e.g., 20 MHz could be configured jointly or together. As an example, when remaining PRB is 5 PRB in the first resource pool and then 2 PRB in the second resource pool, then the remaining PRB could be configured jointly as 7 PRBs. 
     In one implementation, those remaining PRBs jointly configured from more than one resource pool could be configured as a separate resource pool when the remaining PRB size is more than the minimum subchannel size required to create a resource pool. In another implementation, those remaining PRBs jointly configured from more than one resource pool may be configured as empty PRBs and may be allocated in the middle/center of the bandwidth i.e., LBT sub-band and in one example, a parameter is introduced as part of the SL BWP (pre)configuration in RRC indicating the bitmap of the PRB/PRB group as the empty PRBs. 
     According to embodiments of the third solution, a subchannel may be determined based on interleaved PRBs/PRB groups within a resource pool, thereby a single subchannel could be spread across a resource pool. In some embodiments, the remaining PRB from each of the resource pools occupying the minimum occupied bandwidth e.g., 20 MHz could be configured jointly or together. In one implementation, when the amount of remaining PRBs is not large enough for a full subchannel, then these remaining PRBs become empty PRBs that may be configured towards the middle/center of a resource pool. In another implementation, the remaining PRBs may be configured as a subchannel, e.g., of different subchannel size, and interleaved and spread across the resource pool. 
       FIG.  16    depicts an example interlacing structure design  1600  for spread subchannel based on interleaved PRBs (or PRB groups) within a resource pool, according to embodiments of the disclosure. It is assumed that the LBT sub-band spans 20 MHz with SCS=15 kHz. As depicted, the interlacing structure comprises ten groups of interleaved PRBs (i.e., from PRB Group index #0 to PRB Group index #9) formed into two subchannels. A first subchannel (denoted SC #0) is formed from the following PRB groups: #0, #2, #4, #6, and #8. A second subchannel (denoted SC #1) is formed from the following PRB groups: #1, #3, #5, #7, and #9. 
       FIG.  17    depicts an example interlacing structure design  1700  for spread subchannel based on interleaved PRBs (or PRB groups) within a resource pool, according to embodiments of the disclosure. It is assumed that the LBT sub-band spans 20 MHz with SCS=15 kHz. As depicted, the interlacing structure comprises 20 groups of interleaved PRBs (i.e., from PRB Group index #0 to PRB Group index #19) formed into four subchannels. A first subchannel (denoted SC #0) is formed from the following PRB groups: #0, #4, #8, #12, and #16. A second subchannel (denoted SC #1) is formed from the following PRB groups: #1, #5, #9, #13, and #17 A third subchannel (denoted SC #2) is formed from the following PRB groups: #2, #6, #10, #14, and #18. A fourth subchannel (denoted SC #3) is formed from the following PRB groups: #3, #7, #11, #15, and #19. 
     Considering the above option for the sidelink unlicensed operation, an exemplary example of interlacing structure for a resource pool configured with a 20 MHz bandwidth considering different subchannel sizes from 20, 25, 50, 75, 100 for sub-carrier spacing e.g., 15 kHz are shown in the below Table 7. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Sidelink Interlacing configuration for interleaved resource 
               
               
                 pools spanning 20 MHz BW (100 PRBs@15 KHz SCS) 
               
            
           
           
               
               
               
               
            
               
                   
                 Number of 
                   
                   
               
               
                 Subchannel 
                 subchannels in 
                 Remaining 
                 Interlacing structure examples considering 
               
               
                 size (PRBs) 
                 a resource pool 
                 PRBs 
                 15 KHz SCS 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 20 
                 5 
                 0 
                 Option 1: 
               
               
                   
                   
                   
                 Interleave 20 SC into 2 PRB groups of 10 PRBs each 
               
               
                   
                   
                   
                 Option 2: 
               
               
                   
                   
                   
                 Interleave 20 SC into 4 PRB groups of 5 PRBs each 
               
               
                 25 
                 4 
                 0 
                 Interleave 25 SC into 5 PRB groups of 5 PRBs each 
               
               
                 50 
                 2 
                 0 
                 Interleave 25 SC into 5 PRB groups of 10 PRBs each 
               
               
                 75 
                 1 
                 25 
                 Interleave 75 SC into 5 PRB groups of 15 PRBs each 
               
               
                 100 
                 1 
                 0 
                 Interleave 100 SC into 10 PRB groups of 10 PRBs each 
               
               
                   
               
            
           
         
       
     
     In some embodiments, X bits of the PUSCH frequency domain resource allocation field may be used for indicating which combination of M interlaces is allocated to the UE. In one embodiment, the UE receives a bitmap to indicate all possible interlace combinations (e.g., a 10-bit bitmap to indicate one of 10 possible interlace combinations). In another embodiment, the X bits indicate a start interlace index and a number of contiguous interlace indices (e.g., combined into a single value called Resource Indicator Value (“RIV”)) and using remaining RIV values to indicate specific pre-defined interlace combinations. 
       FIG.  18    depicts a user equipment apparatus  1800  that may be used for interlacing sidelink resources, according to embodiments of the disclosure. In various embodiments, the user equipment apparatus  1800  is used to implement one or more of the solutions described above. The user equipment apparatus  1800  may be one embodiment of the remote unit  105  and/or the UE  205 , described above. Furthermore, the user equipment apparatus  1800  may include a processor  1805 , a memory  1810 , an input device  1815 , an output device  1820 , and a transceiver  1825 . 
     In some embodiments, the input device  1815  and the output device  1820  are combined into a single device, such as a touchscreen. In certain embodiments, the user equipment apparatus  1800  may not include any input device  1815  and/or output device  1820 . In various embodiments, the user equipment apparatus  1800  may include one or more of: the processor  1805 , the memory  1810 , and the transceiver  1825 , and may not include the input device  1815  and/or the output device  1820 . 
     As depicted, the transceiver  1825  includes at least one transmitter  1830  and at least one receiver  1835 . In some embodiments, the transceiver  1825  communicates with one or more cells (or wireless coverage areas) supported by one or more base units  121 . In various embodiments, the transceiver  1825  is operable on unlicensed spectrum. Moreover, the transceiver  1825  may include multiple UE panels supporting one or more beams. Additionally, the transceiver  1825  may support at least one network interface  1840  and/or application interface  1845 . The application interface(s)  1845  may support one or more APIs. The network interface(s)  1840  may support 3GPP reference points, such as Uu, N1, PC5, etc. Other network interfaces  1840  may be supported, as understood by one of ordinary skill in the art. 
     The processor  1805 , in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor  1805  may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor  1805  executes instructions stored in the memory  1810  to perform the methods and routines described herein. The processor  1805  is communicatively coupled to the memory  1810 , the input device  1815 , the output device  1820 , and the transceiver  1825 . 
     In various embodiments, the processor  1805  controls the user equipment apparatus  1800  to implement the above described UE behaviors. In certain embodiments, the processor  1805  may include an application processor (also known as “main processor”) which manages application-domain and operating system (“OS”) functions and a baseband processor (also known as “baseband radio processor”) which manages radio functions. 
     In various embodiments, the processor  1805  controls the transceiver  1825  to receive a resource pool configuration (e.g., from network or receiving a pre-configuration of the resource pool) and to receive an interlacing configuration corresponding to the resource pool configuration. Here, the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. Moreover, the interlacing configuration indicates at least: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. Via the transceiver  1825 , the processor  1805  transmits a sidelink channel according to the interlacing configuration within the unlicensed sidelink carrier, the sidelink channel comprising at least one of: a sidelink data channel and a sidelink control channel. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the processor  1805  determines a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     The memory  1810 , in one embodiment, is a computer readable storage medium. In some embodiments, the memory  1810  includes volatile computer storage media. For example, the memory  1810  may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory  1810  includes non-volatile computer storage media. For example, the memory  1810  may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory  1810  includes both volatile and non-volatile computer storage media. 
     In some embodiments, the memory  1810  stores data related to interlacing sidelink resources and/or mobile operation. For example, the memory  1810  may store various parameters, panel/beam configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory  1810  also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus  1800 . 
     The input device  1815 , in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device  1815  may be integrated with the output device  1820 , for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device  1815  includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device  1815  includes two or more different devices, such as a keyboard and a touch panel. 
     The output device  1820 , in one embodiment, is designed to output visual, audible, and/or haptic signals. In some embodiments, the output device  1820  includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device  1820  may include, but is not limited to, a Liquid Crystal Display (“LCD”), a Light-Emitting Diode (“LED”) display, an Organic LED (“OLED”) display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the output device  1820  may include a wearable display separate from, but communicatively coupled to, the rest of the user equipment apparatus  1800 , such as a smart watch, smart glasses, a heads-up display, or the like. Further, the output device  1820  may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like. 
     In certain embodiments, the output device  1820  includes one or more speakers for producing sound. For example, the output device  1820  may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device  1820  includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device  1820  may be integrated with the input device  1815 . For example, the input device  1815  and output device  1820  may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device  1820  may be located near the input device  1815 . 
     The transceiver  1825  communicates with one or more network functions of a mobile communication network via one or more access networks. The transceiver  1825  operates under the control of the processor  1805  to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, the processor  1805  may selectively activate the transceiver  1825  (or portions thereof) at particular times in order to send and receive messages. 
     The transceiver  1825  includes at least transmitter  1830  and at least one receiver  1835 . One or more transmitters  1830  may be used to provide UL communication signals to a base unit  121 , such as the UL transmissions described herein. Similarly, one or more receivers  1835  may be used to receive DL communication signals from the base unit  121 , as described herein. Although only one transmitter  1830  and one receiver  1835  are illustrated, the user equipment apparatus  1800  may have any suitable number of transmitters  1830  and receivers  1835 . Further, the transmitter(s)  1830  and the receiver(s)  1835  may be any suitable type of transmitters and receivers. In one embodiment, the transceiver  1825  includes a first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and a second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum. 
     In certain embodiments, the first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and the second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum may be combined into a single transceiver unit, for example a single chip performing functions for use with both licensed and unlicensed radio spectrum. In some embodiments, the first transmitter/receiver pair and the second transmitter/receiver pair may share one or more hardware components. For example, certain transceivers  1825 , transmitters  1830 , and receivers  1835  may be implemented as physically separate components that access a shared hardware resource and/or software resource, such as for example, the network interface  1840 . 
     In various embodiments, one or more transmitters  1830  and/or one or more receivers  1835  may be implemented and/or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-a-chip, an Application-Specific Integrated Circuit (“ASIC”), or other type of hardware component. In certain embodiments, one or more transmitters  1830  and/or one or more receivers  1835  may be implemented and/or integrated into a multi-chip module. In some embodiments, other components such as the network interface  1840  or other hardware components/circuits may be integrated with any number of transmitters  1830  and/or receivers  1835  into a single chip. In such embodiment, the transmitters  1830  and receivers  1835  may be logically configured as a transceiver  1825  that uses one more common control signals or as modular transmitters  1830  and receivers  1835  implemented in the same hardware chip or in a multi-chip module. 
       FIG.  19    depicts a network apparatus  1900  that may be used for interlacing sidelink resources, according to embodiments of the disclosure. In one embodiment, network apparatus  1900  may be one implementation of a RAN entity, such as the base unit  121  and/or the RAN node  210 , as described above. Furthermore, the network apparatus  1900  may include a processor  1905 , a memory  1910 , an input device  1915 , an output device  1920 , and a transceiver  1925 . 
     In some embodiments, the input device  1915  and the output device  1920  are combined into a single device, such as a touchscreen. In certain embodiments, the network apparatus  1900  may not include any input device  1915  and/or output device  1920 . In various embodiments, the network apparatus  1900  may include one or more of: the processor  1905 , the memory  1910 , and the transceiver  1925 , and may not include the input device  1915  and/or the output device  1920 . 
     As depicted, the transceiver  1925  includes at least one transmitter  1930  and at least one receiver  1935 . Here, the transceiver  1925  communicates with one or more remote units  105 . Additionally, the transceiver  1925  may support at least one network interface  1940  and/or application interface  1945 . The application interface(s)  1945  may support one or more APIs. The network interface(s)  1940  may support 3GPP reference points, such as Uu, N1, N2 and N3. Other network interfaces  1940  may be supported, as understood by one of ordinary skill in the art. 
     The processor  1905 , in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor  1905  may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or similar programmable controller. In some embodiments, the processor  1905  executes instructions stored in the memory  1910  to perform the methods and routines described herein. The processor  1905  is communicatively coupled to the memory  1910 , the input device  1915 , the output device  1920 , and the transceiver  1925 . 
     In various embodiments, the network apparatus  1900  is a RAN node (e.g., gNB) that communicates with one or more UEs, as described herein. In such embodiments, the processor  1905  controls the network apparatus  1900  to perform the above described RAN behaviors. When operating as a RAN node, the processor  1905  may include an application processor (also known as “main processor”) which manages application-domain and operating system (“OS”) functions and a baseband processor (also known as “baseband radio processor”) which manages radio functions. 
     In various embodiments, the processor  1905  controls the apparatus  1900  to configure an interlacing scheme for unlicensed sidelink operation. In some embodiments, the transceiver  1925  transmits (e.g., via an air/radio interface) a resource pool configuration to a UE, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. The transceiver  1925  also transmits an interlacing configuration corresponding to the resource pool configuration to the UE, where the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) the type/method of interlacing to be performed. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the interlacing configuration further indicates a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     The memory  1910 , in one embodiment, is a computer readable storage medium. In some embodiments, the memory  1910  includes volatile computer storage media. For example, the memory  1910  may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory  1910  includes non-volatile computer storage media. For example, the memory  1910  may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory  1910  includes both volatile and non-volatile computer storage media. 
     In some embodiments, the memory  1910  stores data related to interlacing sidelink resources and/or mobile operation. For example, the memory  1910  may store parameters, configurations, resource assignments, policies, and the like, as described above. In certain embodiments, the memory  1910  also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus  1900 . 
     The input device  1915 , in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device  1915  may be integrated with the output device  1920 , for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device  1915  includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device  1915  includes two or more different devices, such as a keyboard and a touch panel. 
     The output device  1920 , in one embodiment, is designed to output visual, audible, and/or haptic signals. In some embodiments, the output device  1920  includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device  1920  may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the output device  1920  may include a wearable display separate from, but communicatively coupled to, the rest of the network apparatus  1900 , such as a smart watch, smart glasses, a heads-up display, or the like. Further, the output device  1920  may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like. 
     In certain embodiments, the output device  1920  includes one or more speakers for producing sound. For example, the output device  1920  may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device  1920  includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device  1920  may be integrated with the input device  1915 . For example, the input device  1915  and output device  1920  may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device  1920  may be located near the input device  1915 . 
     The transceiver  1925  includes at least transmitter  1930  and at least one receiver  1935 . One or more transmitters  1930  may be used to communicate with the UE, as described herein. Similarly, one or more receivers  1935  may be used to communicate with network functions in the PLMN and/or RAN, as described herein. Although only one transmitter  1930  and one receiver  1935  are illustrated, the network apparatus  1900  may have any suitable number of transmitters  1930  and receivers  1935 . Further, the transmitter(s)  1930  and the receiver(s)  1935  may be any suitable type of transmitters and receivers. 
       FIG.  20    depicts one embodiment of a method  2000  for interlacing sidelink resources, according to embodiments of the disclosure. In various embodiments, the method  2000  is performed by a UE device, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1800 , described above as described above. In some embodiments, the method  2000  is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  2000  begins and receives  2005  a resource pool configuration (e.g., from network or receiving a pre-configuration of the resource pool, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. The method  2000  includes receiving  2010  an interlacing configuration corresponding to the resource pool configuration, where the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. The method  2000  includes transmitting  2015  a sidelink channel according to the interlacing configuration within the unlicensed sidelink carrier, the sidelink channel comprising at least one of: a sidelink data channel and a sidelink control channel. The method  2000  ends. 
       FIG.  21    depicts one embodiment of a method  2100  for interlacing sidelink resources, according to embodiments of the disclosure. In various embodiments, the method  2100  is performed by a network entity in a mobile communication network, such as the base unit  121 , the RAN node  210 , and/or the network apparatus  1900 , described above as described above. In some embodiments, the method  2100  is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  2100  begins and transmits  2105  a resource pool configuration to a UE, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. The method  2100  includes transmitting  2110  an interlacing configuration corresponding to the resource pool configuration to the UE, where the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. The method  2100  ends. 
     Disclosed herein is a first apparatus for interlacing sidelink resources, according to embodiments of the disclosure. The first apparatus may be implemented by a UE device, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1800 , described above. The first apparatus includes a transceiver and a processor that receives a resource pool configuration (e.g., from network or receiving a pre-configuration of the resource pool) and receives an interlacing configuration corresponding to the resource pool configuration. Here, the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. Moreover, the interlacing configuration indicates at least: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. The transceiver transmits a sidelink channel according to the interlacing configuration within the unlicensed sidelink carrier, the sidelink channel comprising at least one of: a sidelink data channel and a sidelink control channel. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the processor determines a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     Disclosed herein is a first method for interlacing sidelink resources, according to embodiments of the disclosure. The first method may be performed by a UE device, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1800 , described above. The first method includes receiving a resource pool configuration (e.g., from network or receiving a pre-configuration of the resource pool and receiving an interlacing configuration corresponding to the resource pool configuration. Here, the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. Additionally, the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. The first method includes transmitting a sidelink channel according to the interlacing configuration within the unlicensed sidelink carrier, the sidelink channel comprising at least one of: a sidelink data channel and a sidelink control channel. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the first method includes determining a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     Disclosed herein is a first apparatus for interlacing sidelink resources, according to embodiments of the disclosure. The first apparatus may be implemented by a network entity in a mobile communication network, such as the base unit  121 , the RAN node  210 , and/or the network apparatus  1900 , described above. The first apparatus includes a processor and a transceiver that transmits a resource pool configuration to a UE, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. The transceiver also transmits an interlacing configuration corresponding to the resource pool configuration to the UE, where the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) the type/method of interlacing to be performed. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the interlacing configuration further indicates a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     Disclosed herein is a second method for interlacing sidelink resources, according to embodiments of the disclosure. The second method may be performed by a network entity in a mobile communication network, such as the base unit  121 , the RAN node  210 , and/or the network apparatus  1900 , described above. The second method includes transmitting a resource pool configuration to a UE, where the resource pool configuration indicates a subchannel size and resource pool time-frequency configuration (e.g., bitmap of time slot and frequency resources) for an unlicensed sidelink carrier. The second method also includes transmitting an interlacing configuration corresponding to the resource pool configuration to the UE, where the interlacing configuration indicates: a) a number of subcarriers (or PRBs) per interlace (N) based on the subchannel size, b) a spacing between the interlace (M) based on the subchannel size, c) a minimum amount of resource (e.g., subchannel and/or PRB) to be used for transmission in a resource pool, and d) indicating the type/method of interlacing to be performed. 
     In some embodiments, a resource pool size is not a multiple of the subchannel size. In such embodiments, the interlacing configuration further indicates a bitmap of remaining Physical Resource Blocks (“PRBs”). In one embodiment, the remaining PRBs are configured as empty PRBs in the middle (i.e., center) of the resource pool. In another embodiment, the remaining PRBs are allocated to at least one subcarrier having a second subchannel size different than the subchannel size indicated in the resource pool configuration. 
     In some embodiments, the interlacing configuration further indicates a PRB-level interlacing scheme within each subchannel. In certain embodiments, the PRB-level interlacing scheme extends across multiple subchannels. In certain embodiments, the PRB-level interlacing scheme is a first PRB-level interlacing scheme having allocations starting from a lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. In such embodiments, the interlacing configuration may further indicate a second PRB-level interlacing scheme has allocations starting from a second lowest PRB in each subchannel belonging to an interlacing structure in a resource pool. 
     In some embodiments, the interlacing configuration further indicates an interlacing scheme having allocations starting from both ends (i.e., edges) of the resource pool, the allocations continuing towards the middle (i.e., center) of the resource pool. In certain embodiments, the interlacing scheme comprises at least one of PRB-level interlacing and subchannel-level interlacing. In some embodiments, each subchannel comprises interleaved PRBs (or PRB groups) within the resource pool. 
     In some embodiments, the interlacing configuration comprises multiple subchannel sizes and a bitmap of subchannel indices for each subchannel size. In some embodiments, the resource pool corresponds to a LBT subband. In some embodiments, the interlacing configuration comprises an interleaving scheme for multiple resource pools that occupy a LBT subband. In certain embodiments, a first resource pool of the multiple resource pools has a different subcarrier size than a second resource pool. In certain embodiments, a first resource pool of the multiple resource pools has a different number of subcarriers (e.g., a different resource pool size) than a second resource pool. 
     Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.