Patent Publication Number: US-2023144397-A1

Title: Sidelink Control Information Processing

Description:
PRIORITY INFORMATION 
     The present application is a national phase filing of Patent Cooperation Treaty (PCT) Application No. PCT/CN2019/116235, titled “Sidelink Control Information Processing”, and filed on Nov. 7, 2019, which is hereby incorporated by reference in its entirety as though fully and completely set forth herein. 
    
    
     The claims in the instant application are different than those of the parent application or other related applications. The Applicant therefore rescinds any disclaimer of claim scope made in the parent application or any predecessor application in relation to the instant application. The Examiner is therefore advised that any such previous disclaimer and the cited references that it was made to avoid, may need to be revisited. Further, any disclaimer made in the instant application should not be read into or against the parent application or other related applications. 
     FIELD 
     The present application relates to wireless devices, and more particularly to apparatuses, systems, and methods for wireless devices to utilize sidelink control information (SCI) in vehicle-to-everything (V2X) wireless cellular communications. 
     DESCRIPTION OF THE RELATED ART 
     Wireless communication systems are rapidly growing in usage. One proposed use of wireless communications is in vehicular applications, particularly in V2X (vehicle-to-everything) systems. V2X systems allow for communication between vehicles (e.g., via communications devices housed in or otherwise carried by vehicles), pedestrian UEs (including UEs carried by other persons such as cyclists, etc.), networks, and other wireless communications devices for various purposes, such as to coordinate traffic activity, facilitate autonomous driving, and perform collision avoidance. 
     V2X systems may utilize sidelink communications, wherein two or more V2X systems communicate with each other without routing their communications through an intermediary or a network. Effective utilization of sidelink communications may present unique challenges due to the absence of the network in the communication chain or other reasons. Accordingly, improvements in the field are desirable. 
     SUMMARY 
     Embodiments are presented herein of apparatuses, systems, and methods for performing sidelink communications in vehicle-to-everything (V2X) wireless cellular communications. 
     In some embodiments, a wireless device may perform sidelink communications using a two-stage sidelink control information (SCI) protocol. The two-stage SCI protocol may include Stage 1 SCI messaging carried on a physical sidelink control channel (PSCCH), and Stage 2 SCI messaging carried on a physical sidelink shared channel (PSSCH). The Stage 1 and Stage 2 SCI messaging may be encoded using polar codes. 
     In some embodiments, channel interleaving may be utilized on the Stage 2 SCI messaging to interleave the Stage 2 SCI messaging between two or more layers of a MIMO transmission system. Channel interleaving may be performed either before or after scrambling and modulation is performed. Channel interleaving may be selectively performed based on a modulation order of the polar code, based on whether 2 or more layers are utilized in the PSSCH, based on a mapping of modulation symbols to the two or more layers, and/or based on a pre-configuration of a resource pool utilized by the wireless device. 
     In some embodiments, scrambling for Stage 2 SCI messaging may be performed based at least in part on the result of a cyclic redundancy check (CRC) performed on received Stage 1 SCI messaging. In some embodiments, scrambling for PSSCH data messaging may be performed based at least in part on the result of a CRC performed on received Stage 2 SCI messaging. 
     In some embodiments, collisions between sidelink HARQ feedback to be transmitted to a base station and other transmissions may be avoided based on a priority analysis of the sidelink HARQ feedback. 
     Note that the techniques described herein may be implemented in and/or used with a number of different types of devices, including but not limited to, base stations, access points, cellular phones, portable media players, tablet computers, wearable devices, and various other computing devices. 
     This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present subject matter can be obtained when the following detailed description of various embodiments is considered in conjunction with the following drawings, in which: 
         FIG.  1    illustrates an example vehicle-to-everything (V2X) communication system, according to some embodiments; 
         FIG.  2    illustrates a base station in communication with a user equipment (UE) device, according to some embodiments; 
         FIG.  3    is an example block diagram of a UE, according to some embodiments; 
         FIG.  4    is an example block diagram of a base station, according to some embodiments; 
         FIG.  5    is a table of example priority rankings of different types of uplink transmissions, according to some embodiments; 
         FIG.  6 A  is a flowchart diagram illustrating a transmitter-side method for inserting channel interleaving into a Stage 2 SCI encoding procedure, according to some embodiments; 
         FIG.  6 B  is a flowchart diagram illustrating a receiver-side method for performing channel deinterleaving into a Stage 2 SCI decoding procedure, according to some embodiments; 
         FIG.  7    is a flowchart diagram illustrating a method for selectively inserting channel interleaving into a Stage 2 SCI encoding procedure based on certain conditions, according to some embodiments; and 
         FIG.  8    is a flowchart diagram illustrating a method for avoiding collisions when transmitting sidelink HARQ feedback to a base station, according to some embodiments. 
     
    
    
     While the features described herein may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to be limiting to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the subject matter as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Terms 
     The following is a glossary of terms used in this disclosure: 
     Memory Medium—Any of various types of non-transitory memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a CD-ROM, floppy disks, or tape device; a computer system memory or random-access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g., a hard drive, or optical storage; registers, or other similar types of memory elements, etc. The memory medium may include other types of non-transitory memory as well or combinations thereof. In addition, the memory medium may be located in a first computer system in which the programs are executed, or may be located in a second different computer system which connects to the first computer system over a network, such as the Internet. In the latter instance, the second computer system may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums which may reside in different locations, e.g., in different computer systems that are connected over a network. The memory medium may store program instructions (e.g., embodied as computer programs) that may be executed by one or more processors. 
     Programmable Hardware Element—includes various hardware devices comprising multiple programmable function blocks connected via a programmable interconnect. Examples include FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field Programmable Object Arrays), and CPLDs (Complex PLDs). The programmable function blocks may range from fine grained (combinatorial logic or look up tables) to coarse grained (arithmetic logic units or processor cores). A programmable hardware element may also be referred to as “reconfigurable logic”. 
     Computer System—any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network appliance, Internet appliance, personal digital assistant (PDA), television system, grid computing system, or other device or combinations of devices. In general, the term “computer system” can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium. 
     User Device—as used herein, may refer generally in the context of V2X systems to devices that are associated with mobile actors or traffic participants in a V2X system, i.e., mobile (able-to-move) communication devices such as vehicles and pedestrian user equipment (PUE) devices, as opposed to infrastructure devices, such as base stations, roadside units (RSUs), and servers. 
     Infrastructure Device—as used herein, may refer generally in the context of V2X systems to certain devices in a V2X system that are not user devices, and are not carried by traffic actors (i.e., pedestrians, vehicles, or other mobile users), but rather that facilitate user devices&#39; participation in the V2X network. Infrastructure devices include base stations and roadside units (RSUs). 
     User Equipment (UE) (or “UE Device”)—any of various types of computer systems or devices that are mobile or portable and that perform wireless communications. Examples of UE devices include mobile telephones or smartphones (e.g., iPhone™ Android™-based phones), portable gaming devices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™, iPhone™), laptops, wearable devices (e.g. smartwatch, smart glasses), PDAs, portable Internet devices, music players, data storage devices, or other handheld devices, etc. In general, the term “UE” or “UE device” can be broadly defined to encompass any electronic, computing, and/or telecommunications device (or combination of devices) which is easily transported by a user and capable of wireless communication. 
     Pedestrian UE (PUE) Device—a user equipment (UE) device as regarded in the context of V2X systems that may be worn or carried by various persons, including not only pedestrians in the strict sense of persons walking near roads, but also certain other peripheral or minor participants, or potential participants, in a traffic environment. These include stationary persons, persons not on vehicles who may not necessarily be near traffic or roads, persons jogging, running, skating, and so on, or persons on vehicles that may not substantially bolster the UE&#39;s power capabilities, such as bicycles, scooters, or certain motor vehicles. 
     Base Station—The term “Base Station” has the full breadth of its ordinary meaning, and at least includes a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system. 
     Processing Element—refers to various elements or combinations of elements. Processing elements include, for example, circuits such as an ASIC (Application Specific Integrated Circuit), portions or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices such as a field programmable gate array (FPGA), and/or larger portions of systems that include multiple processors. 
     Channel—a medium used to convey information from a sender (transmitter) to a receiver. It should be noted that since characteristics of the term “channel” may differ according to different wireless protocols, the term “channel” as used herein may be considered as being used in a manner that is consistent with the standard of the type of device with reference to which the term is used. In some standards, channel widths may be variable (e.g., depending on device capability, band conditions, etc.). For example, LTE may support scalable channel bandwidths from 1.4 MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide while Bluetooth channels may be 1 Mhz wide. Other protocols and standards may include different definitions of channels. Furthermore, some standards may define and use multiple types of channels, e.g., different channels for uplink or downlink and/or different channels for different uses such as data, control information, etc. 
     Configured to—Various components may be described as “configured to” perform a task or tasks. In such contexts, “configured to” is a broad recitation generally meaning “having structure that” performs the task or tasks during operation. As such, the component can be configured to perform the task even when the component is not currently performing that task (e.g., a set of electrical conductors may be configured to electrically connect a module to another module, even when the two modules are not connected). In some contexts, “configured to” may be a broad recitation of structure generally meaning “having circuitry that” performs the task or tasks during operation. As such, the component can be configured to perform the task even when the component is not currently on. In general, the circuitry that forms the structure corresponding to “configured to” may include hardware circuits. 
     Various components may be described as performing a task or tasks, for convenience in the description. Such descriptions should be interpreted as including the phrase “configured to.” Reciting a component that is configured to perform one or more tasks is expressly intended not to invoke 35 U.S.C. § 112, paragraph six, interpretation for that component. 
     FIG.  1 —V2X Communication System 
       FIG.  1    illustrates an example vehicle-to-everything (V2X) communication system, according to some embodiments. It is noted that the system of  FIG.  1    is merely one example of a possible system, and that features of this disclosure may be implemented in any of various systems, as desired. 
     Vehicle-to-everything (V2X) communication systems may be characterized as networks in which vehicles, UEs, and/or other devices and network entities exchange communications in order to coordinate traffic activity, among other possible purposes. V2X communications include communications conveyed between a vehicle (e.g., a wireless device or communication device constituting part of the vehicle, or contained in or otherwise carried along by the vehicle) and various other devices. V2X communications include vehicle-to-pedestrian (V2P), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-vehicle (V2V) communications, as well as communications between vehicles and other possible network entities or devices. V2X communications may also refer to communications between other non-vehicle devices participating in a V2X network for the purpose of sharing V2X-related information. 
     V2X communications may, for example, adhere to 3GPP Cellular V2X (C-V2X) specifications, or to one or more other or subsequent standards whereby vehicles and other devices and network entities may communicate. V2X communications may utilize both long-range (e.g., cellular) communications as well as short- to medium-range (e.g., non-cellular) communications. Cellular-capable V2X communications may be called Cellular V2X (C-V2X) communications. C-V2X systems may use various cellular radio access technologies (RATs), such as 4G LTE or 5G NR RATs. Certain LTE standards usable in V2X systems may be called LTE-Vehicle (LTE-V) standards. 
     As shown, the example V2X system includes a number of user devices. As used herein in the context of V2X systems, “user devices” may refer generally to devices that are associated with mobile actors or traffic participants in the V2X system, i.e., mobile (able-to-move) communication devices such as vehicles and pedestrian user equipment (PUE) devices. User devices in the example V2X system include the PUEs  104 A and  104 B and the vehicles  106 A and  106 B. 
     The vehicles  106  may constitute various types of vehicles. For example, the vehicle  106 A may be a road vehicle or automobile, a mass transit vehicle, or another type of vehicle. The vehicles  106  may conduct wireless communications by various means. For example, the vehicle  106 A may include communications equipment as part of the vehicle or housed in the vehicle, or may communicate through a wireless communications device currently contained within or otherwise carried along by the vehicle, such as a user equipment (UE) device (e.g., a smartphone or similar device) installed within the vehicle or carried or worn by a driver, passenger, or other person on board the vehicle, among other possibilities. For simplicity, the term “vehicle” as used herein may include the wireless communications equipment which represents the vehicle and conducts its communications. Thus, for example, when the vehicle  106 A is said to conduct wireless communications, it is understood that, more specifically, certain wireless communications equipment associated with and carried along by the vehicle  106 A is performing said wireless communications. 
     The pedestrian UEs (PUEs)  104  may constitute various types of user equipment (UE) devices, i.e., portable devices capable of wireless communication, such as smartphones, smartwatches, etc., and may be associated with various types of users. Thus, the PUEs  104  are UEs, and may be referred to as UEs or UE devices. Note that although the UEs  104  may be referred to as PUEs (pedestrian UEs), they may not necessarily be carried by persons who are actively walking near roads or streets. PUEs may refer to UEs participating in a V2X system that are carried by stationary persons, by persons walking or running, or by persons on vehicles that may not substantially bolster the devices&#39; power capabilities, such as bicycles, scooters, or certain motor vehicles. Note also that not all UEs participating in a V2X system are necessarily PUEs. 
     The user devices may be capable of communicating using multiple wireless communication standards. For example, the UE  104 A may be configured to communicate using a wireless networking (e.g., Wi-Fi) and/or peer-to-peer wireless communication protocol (e.g., Bluetooth, Wi-Fi peer-to-peer, etc.) in addition to at least one cellular communication protocol (e.g., GSM, UMTS, LTE, LTE-A, LTE-V, HSPA, 3GPP2 CDMA2000, 5G NR, etc.). The UE  104 A may also or alternatively be configured to communicate using one or more global navigational satellite systems (GNSS, e.g., GPS or GLONASS), one or more mobile television broadcasting standards (e.g., ATSC-M/H), and/or any other wireless communication protocol, if desired. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible. 
     As shown, certain user devices may be able to conduct communications with one another directly, i.e., without an intermediary infrastructure device such as base station  102 A or RSU  110 A. As shown, vehicle  106 A may conduct V2X-related communications directly with vehicle  106 B. Similarly, the vehicle  106 B may conduct V2X-related communications directly with PUE  104 B. Such peer-to-peer communications may utilize a “sidelink” interface such as the PC5 interface in the case of some LTE embodiments, and may generally be referred to as “sidelink communications”. In certain LTE embodiments, the PC5 interface supports direct cellular communication between user devices (e.g., between vehicles  106 ), while the Uu interface supports cellular communications with infrastructure devices such as base stations. The LTE PC5/Uu interfaces are used only as an example, and PC5 as used herein may represent various other possible wireless communications technologies that allow for direct sidelink communications between user devices, while Uu in turn may represent cellular communications conducted between user devices and infrastructure devices, such as base stations. For example, NR V2X sidelink communication techniques can also be used to perform device-to-device communications, at least according to some embodiments. Note also that some user devices in a V2X system (e.g., PUE  104 A, as one possibility) may be unable to perform sidelink communications, e.g., because they lack certain hardware necessary to perform such communications. 
     As shown, the example V2X system includes a number of infrastructure devices in addition to the above-mentioned user devices. As used herein, “infrastructure devices” in the context of V2X systems refers to certain devices in a V2X system which are not user devices, and are not carried by traffic actors (i.e., pedestrians, vehicles, or other mobile users), but rather which facilitate user devices&#39; participation in the V2X network. The infrastructure devices in the example V2X system include base station  102 A and roadside unit (RSU)  110 A. 
     The base station (BS)  102 A may be a base transceiver station (BTS) or cell site (a “cellular base station”), and may include hardware that enables wireless communication with user devices, e.g., with the user devices  104 A and  106 A. 
     The communication area (or coverage area) of the base station may be referred to as a “cell” or “coverage”. The base station  102 A and user devices such as PUE  104 A may be configured to communicate over the transmission medium using any of various radio access technologies (RATs), also referred to as wireless communication technologies, or telecommunication standards, such as GSM, UMTS, LTE, LTE-Advanced (LTE-A), LTE-Vehicle (LTE-V), HSPA, 3GPP2 CDMA2000, 5G NR, etc. Note that if the base station  102 A is implemented in the context of LTE, it may alternately be referred to as an eNodeB′, or eNB. Note that if the base station  102 A is implemented in the context of NR, it may alternately be referred to as an gNodeB′, or gNB. 
     As shown, the base station  102 A may also be equipped to communicate with a network  100  (e.g., the V2X network, as well as a core network of a cellular service provider, a telecommunication network such as a public switched telephone network (PSTN), and/or the Internet, among various possibilities). Thus, the base station  102 A may facilitate communication between user devices and/or between user devices and the network  100 . The cellular base station  102 A may provide user devices, such as UE  104 A, with various telecommunication capabilities, such as voice, SMS and/or data services. In particular, the base station  102 A may provide connected user devices, such as UE  104 A and vehicle  106 A, with access to the V2X network. 
     Thus, while the base station  102 A may act as a “serving cell” for user devices  104 A and  106 A as illustrated in  FIG.  1   , the user devices  104 B and  106 B may also be capable of communicating with the base station  102 A. The user devices shown, i.e., user devices  104 A,  104 B,  106 A, and  106 B may also be capable of receiving signals from (and possibly within communication range of) one or more other cells (which might be provided by base stations  102 B-N and/or any other base stations), which may be referred to as “neighboring cells”. Such cells may also be capable of facilitating communication between user devices and/or between user devices and the network  100 . Such cells may include “macro” cells, “micro” cells, “pico” cells, and/or cells which provide any of various other granularities of service area size. For example, base stations  102 A-B illustrated in  FIG.  1    might be macro cells, while base station  102 N might be a micro cell. Other configurations are also possible. 
     Roadside unit (RSU)  110 A constitutes another infrastructure device usable for providing certain user devices with access to the V2X network. RSU  110 A may be one of various types of devices, such as a base station, e.g., a transceiver station (BTS) or cell site (a “cellular base station”), or another type of device that includes hardware that enables wireless communication with user devices and facilitates their participation in the V2X network. 
     RSU  110 A may be configured to communicate using one or more wireless networking communication protocols (e.g., Wi-Fi), cellular communication protocols (e.g., LTE, LTE-V, etc.), and/or other wireless communication protocols. In some embodiments, RSU  110 A may be able to communicate with devices using a sidelink technology such as LTE PC5 or NR V2X sidelink communication techniques. 
     RSU  110 A may communicate directly with user devices, such as the vehicles  106 A and  106 B as shown. RSU  110 A may also communicate with the base station  102 A. In some cases, RSU  110 A may provide certain user devices, e.g., vehicle  106 B, with access to the base station  102 A. While RSU  110 A is shown communicating with vehicles  106 , it may also (or otherwise) be able to communicate with PUEs  104 . Similarly, RSU  110 A may not necessarily forward user device communications to the base station  102 A. In some embodiments, the RSU  110 A and may constitute a base station itself, and/or may forward communications to the server  120 . 
     The server  120  constitutes a network entity of the V2X system, as shown, and may be referred to as a cloud server. Base station  102 A and/or RSU  110 A may relay certain V2X-related communications between the user devices  104  and  106  and the server  120 . The server  120  may be used to process certain information collected from multiple user devices, and may administer V2X communications to the user devices in order to coordinate traffic activity. In various other embodiments of V2X systems, various functions of the cloud server  120  may be performed by an infrastructure device such as the base station  102 A or RSU  110 A, performed by one or more user devices, and/or not performed at all. 
     FIG.  2 —Communication Between a UE and Base Station 
       FIG.  2    illustrates a user equipment (UE) device  104  (e.g., one of the PUEs  104 A or  104 B and/or a UE device comprised within a vehicle  106 A or  106 B in  FIG.  1   ) in communication with a base station  102  (e.g., the base station  102 A in  FIG.  1   ), according to some embodiments. The UE  104  may be a device with cellular communication capability such as a mobile phone, a hand-held device, a computer or a tablet, or virtually any type of portable wireless device. 
     The UE  104  may include a processor that is configured to execute program instructions stored in memory. The UE  104  may perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or in addition, the UE  104  may include a programmable hardware element such as an FPGA (field-programmable gate array) that is configured to perform any of the method embodiments described herein, or any portion of any of the method embodiments described herein. 
     The UE  104  may include one or more antennas for communicating using one or more wireless communication protocols or technologies. In some embodiments, the UE  104  may be configured to communicate using, for example, CDMA2000 (1×RTT/1×EV-DO/HRPD/eHRPD) or LTE using a single shared radio and/or GSM or LTE using the single shared radio. The shared radio may couple to a single antenna, or may couple to multiple antennas (e.g., for MIMO) for performing wireless communications. In general, a radio may include any combination of a baseband processor, analog RF signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc.), or digital processing circuitry (e.g., for digital modulation as well as other digital processing). Similarly, the radio may implement one or more receive and transmit chains using the aforementioned hardware. For example, the UE  104  may share one or more parts of a receive and/or transmit chain between multiple wireless communication technologies, such as those discussed above. 
     In some embodiments, the UE  104  may include separate transmit and/or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As a further possibility, the UE  104  may include one or more radios which are shared between multiple wireless communication protocols, and one or more radios which are used exclusively by a single wireless communication protocol. For example, the UE  104  might include a shared radio for communicating using either of LTE or 1×RTT (or LTE or GSM), and separate radios for communicating using each of Wi-Fi and Bluetooth. Other configurations are also possible. 
     FIG.  3 —Block Diagram of a UE 
       FIG.  3    illustrates an example block diagram of a UE  104 , according to some embodiments. As shown, the UE  104  may include a system on chip (SOC)  300 , which may include portions for various purposes. For example, as shown, the SOC  300  may include processor(s)  302  which may execute program instructions for the UE  104  and display circuitry  304  which may perform graphics processing and provide display signals to the display  360 . The processor(s)  302  may also be coupled to memory management unit (MMU)  340 , which may be configured to receive addresses from the processor(s)  302  and translate those addresses to locations in memory (e.g., memory  306 , read only memory (ROM)  350 , NAND flash memory  310 ) and/or to other circuits or devices, such as the display circuitry  304 , wireless communication circuitry  330 , connector I/F  320 , and/or display  360 . The MMU  340  may be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU  340  may be included as a portion of the processor(s)  302 . 
     As shown, the SOC  300  may be coupled to various other circuits of the UE  104 . For example, the UE  104  may include various types of memory (e.g., including NAND flash memory  310 ), a connector interface  320  (e.g., for coupling to a computer system, dock, charging station, etc.), the display  360 , and wireless communication circuitry  330  (e.g., for LTE, LTE-A, LTE-V, 5G NR, CDMA2000, Bluetooth, Wi-Fi, GPS, etc.). The UE may also include at least one SIM device, and may include two SIM devices, each providing a respective international mobile subscriber identity (IMSI) and associated functionality. 
     As shown, the UE device  104  may include at least one antenna (and possibly multiple antennas, e.g., for MIMO and/or for implementing different wireless communication technologies, among various possibilities) for performing wireless communication with base stations, access points, and/or other devices. For example, the UE device  104  may use antenna  335  to perform the wireless communication. 
     The UE  104  may also include and/or be configured for use with one or more user interface elements. The user interface elements may include any of various elements, such as display  360  (which may be a touchscreen display), a keyboard (which may be a discrete keyboard or may be implemented as part of a touchscreen display), a mouse, a microphone and/or speakers, one or more cameras, one or more buttons, and/or any of various other elements capable of providing information to a user and/or receiving or interpreting user input. 
     As described herein, the UE  104  may include hardware and software components for implementing features for performing unicast sidelink access stratum level connection maintenance, such as those described herein. The processor  302  of the UE device  104  may be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, processor  302  may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit). Alternatively (or in addition) the processor  302  of the UE device  104 , in conjunction with one or more of the other components  300 ,  304 ,  306 ,  310 ,  320 ,  330 ,  335 ,  340 ,  350 ,  360  may be configured to implement part or all of the features described herein, such as the features described herein. 
     FIG.  4 —Block Diagram of a Base Station 
       FIG.  4    illustrates an example block diagram of a base station  102  (e.g., base station  102 A in  FIG.  1   ), according to some embodiments. It is noted that the base station of  FIG.  4    is merely one example of a possible base station. As shown, the base station  102  may include processor(s)  404  which may execute program instructions for the base station  102 . The processor(s)  404  may also be coupled to memory management unit (MMU)  440 , which may be configured to receive addresses from the processor(s)  404  and translate those addresses to locations in memory (e.g., memory  460  and read only memory (ROM)  450 ) or to other circuits or devices. 
     The base station  102  may include at least one network port  470 . The network port  470  may be configured to couple to a telephone network and provide a plurality of devices, such as UE devices  104 , access to the telephone network 
     The network port  470  (or an additional network port) may also or alternatively be configured to couple to a cellular network, e.g., a core network of a cellular service provider. The core network may provide mobility related services and/or other services to a plurality of devices, such as UE devices  104 . In some cases, the network port  470  may couple to a telephone network via the core network, and/or the core network may provide a telephone network (e.g., among other UE devices serviced by the cellular service provider). 
     The base station  102  may include at least one antenna  434 , and possibly multiple antennas. The at least one antenna  434  may be configured to operate as a wireless transceiver and may be further configured to communicate with UE devices  104  via radio  430 . The antenna  434  communicates with the radio  430  via communication chain  432 . Communication chain  432  may be a receive chain, a transmit chain or both. The radio  430  may be configured to communicate via various wireless communication standards, including, but not limited to, LTE, LTE-A, LTE-V, GSM, UMTS, CDMA2000, 5G NR, Wi-Fi, etc. 
     The base station  102  may be configured to communicate wirelessly using multiple wireless communication standards. In some instances, the base station  102  may include multiple radios, which may enable the base station  102  to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station  102  may include an LTE radio for performing communication according to LTE as well as a Wi-Fi radio for performing communication according to Wi-Fi. In such a case, the base station  102  may be capable of operating as both an LTE base station and a Wi-Fi access point. As another possibility, the base station  102  may include a multi-mode radio which is capable of performing communications according to any of multiple wireless communication technologies (e.g., LTE and NR, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.). 
     As described further subsequently herein, the BS  102  may include hardware and software components for implementing or supporting implementation of features described herein. The processor  404  of the base station  102  may be configured to implement or support implementation of part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, the processor  404  may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. Alternatively (or in addition) the processor  404  of the BS  102 , in conjunction with one or more of the other components  430 ,  432 ,  434 ,  440 ,  450 ,  460 ,  470  may be configured to implement or support implementation of part or all of the features described herein. 
     Sidelink Communications 
     In wireless communications, specifically cellular wireless communications, sidelink communications represent a special kind of communication mechanism between devices that is not carried through a base station, e.g., through an eNB/gNB. In other words, the devices communicate with each other without that communication going through a base station. In one sense, the devices may be said to be communicating with each other directly. Accommodation of such communication, however, may utilize new physical layer designs and protocols. 
     Many recent studies have identified the need for technical solutions for sidelink design, e.g. a sidelink design in 5G-NR, to meet the requirements of advanced V2X services, including support of sidelink unicast, sidelink groupcast and sidelink broadcast. A number of specific use cases have been identified for advanced V2X services, categorized into four groups: vehicle platooning, extended sensors, advanced driving, and remote driving. Platooning is a cooperative driving application according to which multiple vehicles travel in the same lane as in a convoy, keeping a specified (preferably constant) inter-vehicle distance between each other in order to increase their traffic efficiency, e.g. to reduce fuel consumption and gas emissions and to achieve safe and efficient transport. To achieve platooning, vehicles in a platoon may use multiple on-board sensors (e.g., radars, lidars—light detection and ranging, positioning systems, etc.) and sidelink vehicle-to-vehicle communications to synchronize their on-road operations, e.g. pertaining to breaking, changing lanes, stopping, etc. Vehicle platooning may utilize both groupcast transmissions (e.g. for relaying status information for platoon management) and unicast transmissions (e.g. for communication between two members). Efficient intra-platooning communications and inter-platooning communications may help achieve better spectrum/power efficiency while maintaining fair resource competition, e.g. between members of the same platoon and also between platoons, (consequently, between members of different platoons). 
     In C-V2X, multiple resource allocation modes may be employed for sidelink communications, with different mechanisms for allocating sidelink communication resources. For example, C-V2X may utilize “mode 1”, whereby sidelink communication resources are allocated by the network (NW) (for example, through dynamic scheduling or semi-persistent scheduling (SPS)), or “mode 2”, where resource allocation is performed autonomously by the UE (e.g., such that the UE autonomously selects the resources to use for communications), as specified by LTE Release 12. Alternatively or additionally, C-V2X may utilize “mode 3” which operates similar to mode 1 (i.e., sidelink communication resources are allocated by the NW), and “mode 4’ which operates similar to mode 2 (i.e., resource allocation is performed autonomously by the UE), as specified by LTE release 14. In this context, “resource allocation” may be understood to refer to the allocation of one or both of time slots and/or frequency slots (e.g., subcarriers) for use in performing sidelink communications. The resources may be allocated within one or more “pools”, in some embodiments. For example, a “mode 2 pool” of time slots and corresponding subcarrier frequencies may be configured by a base station, wherein the mode 2 pool describes the set of time and frequency resources available for performing mode 2 sidelink communications. Additionally or alternatively, an “exceptional pool” may be utilized by a UE during a transition from RRC_Idle to RRC_Connected, and a “pre-configured pool” may be pre-configured for a UE to use, in certain circumstances. 
     In some embodiments, a dual-mode UE (or mixed-mode UE) may be utilized, whereby the UE is able to switch between mode 1 and mode 2 operation. Advantageously, a dual-mode UE may be employed without introducing backwards-compatibility issues with other UEs, as the receiving UE may be transparent to the transmitting mode used. For example, if a 5GNR-V2X UE supports dual-mode operation, it may apply it even to LTE V2X R14 transmissions. For example, it may alternate mode selection to transmit basic safety messages (BSM) in a R14 format. 
     In some embodiments, a UE may only be capable of communicating according to one mode at one time. For example, at one time, all sidelink transmissions may be of the same mode. Alternatively, in some embodiments a UE may support simultaneous dual-mode operation, whereby at one time some sidelink transmissions are done in mode 1, and other sidelink transmissions are done in mode 2. 
     Two-Stage Sidelink Control Information in V2X 
     V2X communications operating through the 5G NR radio access technology may support a two-stage sidelink control information (SCI) protocol, including both Stage 1 SCI messaging and Stage 2 SCI messaging. In this protocol, Stage 1 SCI messaging may be carried on a physical sidelink control channel (PSCCH), and may include transmissions specifying radio resources (e.g., time and/or frequency resources) being utilized or reserved by vehicles and other devices in a V2X environment. It is expected that polar codes, adopted for NR downlink control information (DCI), may be applied to Stage 1 SCI transmissions on the PSCCH. Stage 2 SCI messages may be carried on a physical sidelink shared channel (PSSCH), and may include sidelink hybrid automatic repeat request (HARQ) feedback between sidelink devices, among other types of transmissions. Embodiments herein present methods and devices to improve performance for two-stage SCI protocols. 
     The polar coding protocols used for the physical downlink control channel (PDCCH) may be applied to Stage 2 SCI messaging, and the scrambling operations for Stage 2 SCI may be applied separately for the PSSCH. The PSSCH may be further utilized for data transfers between V2X devices, and in some embodiments Stage 2 SCI messaging may be interlaced with resource elements (REs) utilized for data transfers in the PSSCH. Alternatively, Stage 2 SCI messaging may utilize REs that are not interspersed with REs utilized for data transfers. Modulation for Stage 2 SCI messaging may utilize quadrature phase shift keying (QPSK), or alternatively it may utilize the same modulation scheme as data messages transferred over the PSSCH. 
     In some embodiments, the PSSCH may utilize multiple layers for transmitting and receiving information. For example, a V2X-capable device may utilize a multiple-input multiple-output (MIMO) radio, and different transmit antennas may be separately allocated to a first transmission layer and a second transmission layer. When the PSSCH has two layers, the same modulation symbol of the 2nd stage SCI may be mapped to the two layers, different modulation symbols of the 2nd stage SCI may be mapped to the two layers, or a combination thereof may be employed, in various embodiments. 
     In some embodiments, V2X sidelink communications may operate autonomously between peer devices without scheduling and direction from a base station. Because of the lack of coordination from the base station, collisions (e.g., resource conflicts) may arise between different V2X transmissions. To mitigate collisions, different types of V2X communications may incorporate a priority ranking to determine which types of communications take precedence during a potential collision.  FIG.  5    is a table illustrating an example priority ranking for ultra-reliable low latency communications (URLLC) scheduling requests (SR), URLLC HARQ acknowledgment (ACK) messaging, periodic/semi-persistent (P/SP) channel state information (CSI) on the physical uplink control channel (PUCCH), and URLLC on the physical uplink shared channel (PUSCH) for Release 16. As illustrated,  FIG.  5    shows which procedure should be followed during a resource collision between different pairs of communication types. In some cases, the priority ranking from Release 15 (Rel-15) may be used. P/SP CSI may always have low priority, and aperiodic CSI (A-CSI) priority may depend on the priority of the PUSCH carrying the A-CSI (not illustrated). 
     Given the state of SCI messaging in V2X systems, embodiments herein present methods and devices to improve functionality in these environments. For example, the physical layer processing of SCI stage 2 messaging may include modulation, resource mapping, and layer mapping, and some embodiments herein present methods and devices to maintain a specified level of SCI stage 2 polar coding performance for any given modulation, resource mapping and layer mapping. Additionally, some embodiments present implementations for the scrambling sequence for PSSCH and/or designs for the PSSCH demodulation reference signal (DMRS) sequence. The scrambling sequence for SCI stage 2 may be different from the scrambling sequence for sidelink data transmissions, in some embodiments. Additionally, for environments where a V2X-capable device is operating in an in-coverage or partial coverage scenario (i.e., when it is communicating with a base station to facilitate V2X sidelink communications), the device may transmit sidelink HARQ feedback on the PUCCH and/or the PUSCH, which may potentially conflict with other transmissions such as other uplink transmissions. In these cases, embodiments herein present methods and devices to mitigate these collisions. 
     Channel Interleaver Applied to SCI Stage 2 
     Typically, channel interleaving is not utilized for communications on the PDCCH, because modulation for polar coding DCI on the PDCCH is QPSK, and there is typically no difference between the reliability of the two bits in a QPSK symbol. Further, a single layer is typically applied to PDCCH transmissions. The PSSCH, on the other hand, utilizes two layers, and embodiments herein present methods for mapping different modulation symbols of Stage 2 SCI messaging to the two layers. In these embodiments, layer 1 may generally have a better signal-to-interference-plus-noise ratio (SINR) than layer 2. Accordingly, coded bits allocated to layer 1 may be better protected than the coded bits allocated to layer 2. 
     In some embodiments, fading patterns during transmission for polar encoded bits may result in polar decoding performance degradation. When the modulation order of the 2nd stage SCI is same as that used for PSSCH data transmission, a high order modulation (e.g., 16QAM or 64 QAM or 256 QAM) may be applied to the polar encoded bits to improve performance. The coded bits allocated to the most significant bits (MSBs) of modulation symbols may be better protected than the coded bits allocated to the least significant bits (LSBs) of modulation symbols. 
     To address these and other concerns, in some embodiments, a channel interleaver may be utilized for Stage 2 SCI messaging to randomize deep fading of the polar encoded bits between the two layers. The channel interleaver may be applied after polar encoding and rate matching, in some embodiments. In various embodiments, channel interleaving may be applied before or after scrambling and/or before or after modulation is performed. Various types of channel interleavers may be utilized, including but not limited to a triangular interleaver, a block interleaver, or two or more parallel block interleavers with interlacing combining. 
     In some embodiments, a Stage 2 SCI message may have attached thereon a cyclic redundancy check (CRC), which may be a 24-bit CRC or another size CRC. Interleaving of a Stage 2 SCI message and the CRC may be performed to achieve CRC distribution. Polar encoding may be performed with a maximum mother code length of 512 bits or another length of bits, followed by rate matching which may include subblock interleaving on polar coded bits, saving interleaved bits to a circular buffer, selecting a rate matching scheme based on the code rate and the number of rate matching output bits, and selecting bits from the circular buffer based on the rate matching scheme. 
     FIGS.  6 - 7 —Flowchart for Channel Interleaving and Scrambling Design 
       FIG.  6 A  is a flowchart diagram illustrating a transmitter-side method for inserting channel interleaving into a Stage 2 SCI encoding procedure, according to some embodiments. The Stage 2 SCI may be associated with a two-stage SCI protocol associated with 5G NR communications, in some embodiments. The method described in  FIG.  6 A  may be performed by a wireless device configured with at least one antenna for performing wireless communications, a radio coupled to the at least one antenna, and a processor coupled to the radio. The wireless device may be comprised within a vehicle, in some embodiments. In various embodiments, some of the elements of the methods shown may be performed concurrently, in a different order than shown, may be substituted for by other method elements, or may be omitted. Additional method elements may also be performed as desired. As shown, the method may operate as follows. 
     The wireless device may have sidelink control information (SCI) to be polar encoded and transmitted as a Stage 2 SCI message. As described in greater detail below, steps  602 - 608  may proceed similarly to a standard polar coding chain for PDCCH communications. 
     At  602 , upon initialization of Stage 2 SCI encoding, cyclic redundancy check (CRC) bits may be attached to the SCI to be encoded. As illustrated, the CRC may be a 24 bit CRC, although other lengths of CRC bits may also be used, as desired. 
     At  604 , the CRC may be distributed throughout the SCI, according to standard polar encoding protocols. 
     At  606 , polar encoding may be performed on the SCI message to obtain polar encoded SCI. 
     At  608 , rate matching may be performed on the polar encoded SCI according to standard protocols, to match the bit rate of the message to be transmitted to a desired bit rate. 
     At  610  channel interleaving may be performed. The channel interleaving may utilize triangular interleaving, which may reuse the NR uplink control information (UCI) polar coding protocol, for example, by setting I BIL  equal to one. Alternatively, block interleaving or parallel block interleaving with interlacing combining may be utilized. Channel interleaving may distribute the polar encoded SCI between the two or more layers of the MIMO antenna system of the wireless device. 
     At  612  scrambling may be performed on the polar encoded SCI. In some embodiments, scrambling for Stage 2 SCI messaging may be performed at least in part in response to the result of a CRC performed on Stage 1 SCI messaging. For example, the wireless device may determine the result of a CRC performed on an SCI message associated with Stage 1 and received by the wireless device from a remote device over the PSCCH. As described in greater detail below, the Stage 2 SCI may be scrambled based on a random or pseudorandom number such as a Gold sequence, and this pseudorandom number may be initialized based on an initialization value that is determined based at least in part on the result of the CRC performed on the received Stage 1 SCI. In some embodiments, the wireless device may utilize one or more other values to initialize the pseudorandom sequence. For example, the wireless device may use one or more of an identifier of the remote device or an identifier of the wireless device to obtain an initialization value for use in scrambling the Stage 2 SCI message. 
     While step  612  describes embodiments related to scrambling a Stage 2 SCI message based on the result of a CRC performed on a Stage 1 SCI message, other embodiments are also possible. For example, the CRC may be performed on a Stage 2 SCI message received from the remote device over the PSSCH, and the result of the CRC may be utilized to determine an initialization value for scrambling a data message to be transmitted over the PSSCH. In these embodiments, an identifier of one or both of the wireless device and the remote device may additionally or alternatively be utilized to determine the initialization value for scrambling the data message. Additionally or alternatively, the wireless device may scramble a demodulation reference signal (DMRS) based on an initialization value determined from a result of the CRC performed on a received Stage 1 SCI, and may transmit the scrambled DMRS to the remote device over the PSSCH. 
     At  614 , modulation may be performed according to any desired modulation scheme to modulate the SCI prior to transmission. 
     While  FIG.  6 A  shows scrambling and modulation occurring after channel interleaving, in various embodiments channel interleaving may be performed after scrambling and before modulation, or after each of scrambling and modulation. In other words, the ordering of steps  610 - 614  may be altered such that step  610  occurs anywhere within the sequence. 
     At  616 , layer mapping and resource mapping may be performed. 
     At  618 , the polar encoded sidelink information may be transmitted to a remote device according to the channel interleaving on a physical sidelink shared channel (PSSCH). 
       FIG.  6 B  is a flowchart diagram illustrating a receiver-side method for performing channel deinterleaving during a Stage 2 SCI decoding procedure, according to some embodiments. The Stage 2 SCI may be associated with a two-stage SCI protocol associated with 5G NR communications, in some embodiments. The method described in  FIG.  6 B  may be performed by a wireless device configured with at least one antenna for performing wireless communications, a radio coupled to the at least one antenna, and a processor coupled to the radio. The wireless device may be comprised within a vehicle, in some embodiments. In various embodiments, some of the elements of the methods shown may be performed concurrently, in a different order than shown, may be substituted for by other method elements, or may be omitted. Additional method elements may also be performed as desired. As shown, the method may operate as follows. 
     At  620 , a polar encoded message may be received by a radio of the wireless device. The polar encoded message may be received wirelessly from a peer device using a cellular technology such as 5G NR, and may be received over a sidelink connection. 
     At  622 , resource demapping and layer demapping may be performed on the received message. 
     At  624 , demodulation may be performed on the received message. Demodulation may be performed according to any desired modulation scheme, such as QAM or QPSK, among other possibilities. 
     At  626 , the received message may be descrambled. 
     At  628 , channel deinterleaving may be performed on the received message. 
     At  630 , rate matching may be performed on the received message. 
     At  632 , polar decoding may be performed on the received message to obtain a decoded message. 
     At  634 , CRC distribution, check and removal may be performed on the decoded message, to determine whether the wireless device is the intended recipient of the received message. If the CRC is successful, the wireless device may proceed to process the decoded Stage 2 SCI message. 
       FIG.  7    is a similar flowchart to  FIG.  6 A , except  FIG.  7    describes embodiments where channel interleaving is selectively applied based on certain conditions. The method described in  FIG.  6 A  may be performed by a wireless device configured with at least one antenna for performing wireless communications, a radio coupled to the at least one antenna, and a processor coupled to the radio. The wireless device may be comprised within a vehicle, in some embodiments. In various embodiments, some of the elements of the methods shown may be performed concurrently, in a different order than shown, may be substituted for by other method elements, or may be omitted. Additional method elements may also be performed as desired. As shown, the method may operate as follows. 
     Steps  702 - 708  may proceed similarly to corresponding steps  602 - 608  of  FIG.  6 A , described above. 
     At  710 , it may be determined whether conditions or met for performing channel interleaving. Any of a variety of conditions, or combinations of conditions, may be used for determining whether to perform channel interleaving, according to various embodiments. For example, in some embodiments, channel interleaving is applied if the PSSCH has a high order modulation such as 16 QAM of higher order modulation. More generally, the wireless device may determine whether the PSSCH utilized a modulation order higher than a threshold order, and channel interleaving may be performed based at least in part on this determination. 
     Alternatively or additionally, channel interleaving may be applied if the PSSCH has 2 or more layers and different modulation symbols of Stage 2 SCI are mapped to these two or more layers. In some embodiments, channel interleaving may not be applied if the PSSCH utilizes a low order modulation such as QPSK modulation and/or if the PSSCH has 1 layer, and/or if the PSSCH has 2 or more layers but the same modulation symbols of Stage 2 SCI are mapped to these 2 or more layers. 
     In some embodiments, channel interleaving may be selectively applied based on a pre-configuration of the wireless device and a peer device. For example, the wireless device may conduct communications with the peer device to determine a pre-configuration associated with a resource pool used to communication with the peer device. The wireless device may determine whether the resource pool used to communication with the peer device supports channel interleaving. In these embodiments, channel interleaving may be performed at least in part in response to determining that the pre-configuration associated with the resource pool used for communication with the remote device supports channel interleaving. In various embodiments, the pre-configuration may be specified per resource pool and/or per ProSe sidelink radio resource control (PC5-RRC) configuration. 
     At  712 , if it is determined that one or more conditions are met for performing channel interleaving, channel interleaving is performed according to the description above in reference to step  610  of  FIG.  6 A . 
     At  714 - 718 , scrambling, modulation, layer mapping and resource mapping may be performed, similar to steps  612 - 616  described above in reference to  FIG.  6 A . However, steps  714 - 718  may alternatively be performed without also performing channel interleaving (e.g., if conditions for performing channel interleaving are not met) or in conjunction with channel interleaving (i.e., if the conditions are met). Similar to  FIG.  6 A , while steps  714  and  716  are illustrated as taking place after steps  710  and  712 , channel interleaving (and the decision whether to perform channel interleaving) may alternatively occur before or after either of scrambling and modulation, as desired. 
     At  720 , the polar encoded sidelink information may be transmitted to a remote device according to the channel interleaving on a physical sidelink shared channel (PSSCH). 
     Scrambling Sequence Design for SCI Messaging 
     In some embodiments, methods and devices may be utilized to enhance the scrambling sequence design for Stage 2 SCI messaging on the PSSCH. The following paragraphs provide further details on the scrambling step performed, for example, at steps  612  and  714  of  FIGS.  6  and  7   , respectively. 
     Polar codes may typically utilize a pseudorandom sequence (such as a Gold sequence or another type of pseudorandom sequence) for scrambling, and the pseudorandom sequence may be seeded with an initialization value. In some embodiments, scrambling for Stage 2 SCI messaging may utilize an initialization value that is based at least in part on the result of a cyclic redundancy check (CRC) performed over the PSCCH, such as a Stage 1 SCI CRC, for example. In various embodiments, either part (e.g., the LSBs or MSBs) or all of the PSCCH CRC bits may be used to determine the initialization value. Additionally or alternatively, the initialization value may depend on a destination ID (e.g., an ID of the peer device) or combination of the destination ID and the PSCCH CRC. 
     As one specific example, the initialization value C init  for the Stage 2 SCI may be computed as follows: 
         C   init   =N   ID *2 7   +N   Const , 
     where N ID  is the 24-bit PSCCH CRC and N Const  is a constant value. 
     Another example for computing C init  is as follows: 
         C   init   =N   ID *2 10   +N   Const , 
     where N ID  represents the 21 (MSB or LSB) bits of the PSCCH CRC and N Const  is a constant value between 1008 and 1023. 
     In some embodiments, the initialization value for scrambling data messaging on the PSSCH may be determined based at least in part on the destination ID, the source ID (i.e., an identifier of the transmitting wireless device), the PSCCH CRC, and/or the Stage 2 SCI CRC. As one example, C init  for data messaging on the PSSCH may be computed as follows: 
     C init =N ID *2 24 +N destinationID *2 8 +N sourceID , where N ID  represents the 7 (MSB or LSB) bits of the Stage 2 SCI CRC, N destinationID  is ID the destination (which may be 16 bits in some embodiments) and N sourceID  is the source ID (which may be 8 bits in some embodiments). 
     In some embodiments, the initialization value for scrambling demodulation reference signals (DMRSs) on the PSCCH may be determined based at least in part on the result of the PSCCH CRC (or the Stage 1 SCI CRC). Similar to the Stage 2 SCI messaging, either part (e.g., the LSBs or MSBs) or all of the PSCCH CRC bits may be used to determine the initialization value for the DMRS. Alternatively, the destination ID or a combination of destination ID and the PSCCH CRC may be utilized to determine the initialization value. 
     Note that in some embodiments the source ID may not be usable to generate the initialization value for scrambling the PSSCH DMRS sequence, as it may be contained in Stage 2 SCI, which is typically decoded by using the PSSCH DMRS sequence for channel estimation. An example equation for calculating the initialization value for scrambling the DRMS sequence is as follows: 
         C   init =(2 10 *(14 n   s,f   +l+ 1)(2* N   ID +1)+ N   ID )mod 2 31 , 
     where N ID  is the 10 (MSB or LSB) bits of the PSCCH CRC, l is the OFDM symbol number within a slot, and n s,f  is the slot number within a radio frame. 
     Avoiding Sidelink HARQ Feedback Collisions 
     In some embodiments, a wireless device such as a V2X-capable wireless device may perform sidelink communications in an in-coverage or partial coverage scenario, and the wireless device may report sidelink HARQ feedback to the base station (e.g., the eNB or the gNB). In these embodiments, timing for transmitting sidelink HARQ feedback may be indicated to the wireless device by the base station through DCI messaging. Adversely, sidelink HARQ feedback may be scheduled such that it may collide with other uplink or downlink transmissions, including UL or DL HARQ messaging, scheduling requests (SR), channel state information (CSI) reporting, and/or uplink data transmissions. Further, the multiplexing of sidelink HARQ messaging with uplink control information (UCI) may complicate UE operations. To address these and other concerns, some embodiments propose priority-based handling of sidelink HARQ messaging and other transmissions. 
     In some embodiments, the priority of sidelink HARQ messaging may be based at least in part on the priority of the associated sidelink data. In some embodiments, there may be up to 8 or more priority levels. Similarly, the priority of downlink HARQ messaging may depend on the priority of associated downlink data, with up to 2 or more priority levels. 
     In some embodiments, if there is a potential collision between sidelink HARQ messaging transmitted on an UL channel and an uplink data communication, the wireless device may piggyback the sidelink HARQ messaging with the uplink data communication on the PUSCH. It may be understood that ‘piggyback’ as used herein may refer to transmitting the two communications concurrently as part of a single transmission. Alternatively, the behavior of the wireless device may depend on the relative priority of the sidelink HARQ messaging and the uplink data communication. For example, if the sidelink HARQ messaging and the uplink data communication are of the same priority class, then the wireless device may piggyback the sidelink HARQ messaging with the uplink data communication. If they do not have the same priority class, the wireless device may drop (i.e., the wireless device may refrain from transmitting or postpone transmitting) the communication with the lower priority. 
     In some embodiments, there may be a potential collision between sidelink HARQ messaging to be transmitted on an UL channel and another type of second transmission. The second transmission may include P/SP CSI reporting on the PUCCH, uplink SR messaging, downlink HARQ messaging, or another type of transmission. In some embodiments, the wireless device may, by default (i.e, without consulting priority), determine to transmit the sidelink HARQ messaging and drop the second transmission. Alternatively, the wireless device may determine its behavior based on the priority of the sidelink HARQ messaging. For example, if the sidelink HARQ priority is higher than a threshold, then the second transmission may be dropped and the sidelink HARQ message may be performed according to the indicated timing. As yet another possibility, the priority of the sidelink HARQ messaging may be compared with the priority of the second transmission, and the higher priority transmission may be performed according to its respective schedule, while the lower priority transmission may be postponed or cancelled. In some embodiments, if both the sidelink HARQ messaging and the second transmission have the same priority, the sidelink HARQ messaging may piggyback on the second transmission, if possible. 
     FIG.  8 —Flowchart for Priority-Based Sidelink HARQ Collision Mitigation 
       FIG.  8    is a flowchart diagram illustrating a method for avoiding collisions when transmitting sidelink HARQ feedback to a base station, according to some embodiments. The sidelink HARQ feedback may be associated with 5G NR communications, in some embodiments. The method described in  FIG.  8    may be performed by a wireless device configured with at least one antenna for performing wireless communications, a radio coupled to the at least one antenna, and a processor coupled to the radio. The wireless device may be included within a vehicle, in some embodiments. In various embodiments, some of the elements of the methods shown may be performed concurrently, in a different order than shown, may be substituted for by other method elements, or may be omitted. Additional method elements may also be performed as desired. As shown, the method may operate as follows. 
     At  802 , downlink control information (DCI) is received from a base station indicating timing for the wireless device to transmit sidelink hybrid automatic repeat request (HARQ) feedback to the base station. The base station may be an eNB or a gNB, in various embodiments. The DCI may further specify one or more frequency resources for the wireless device to use in transmitting the sidelink HARQ feedback to the base station. 
     At  804 , it is determined that the indicated timing for transmitting the sidelink HARQ feedback conflicts with a second transmission. For example, it may be determined that the sidelink HARQ feedback overlaps in time and/or frequency with a second transmission. The second transmission may be of various types, in either the uplink or downlink direction. For example, the second transmission may include periodic/semi-persistent (P/SP) channel state information (CSI) reporting on an uplink channel, an uplink scheduling request, or a downlink HARQ message, in various embodiments. 
     At  806 , a priority of sidelink data associated with the sidelink HARQ feedback is determined based at least in part on determining that the indicated timing for transmitting the sidelink HARQ feedback conflicts with the second transmission. For example, the wireless device may determine a priority of the sidelink data for which the sidelink HARQ feedback is reporting successful or unsuccessful reception. 
     At  808 , based at least on the priority of the sidelink data, the sidelink HARQ feedback is transmitted to the base station according to the indicated timing. In some embodiments, determining the priority of the sidelink data includes determining whether the priority of the sidelink data is higher than a predetermined threshold. In these embodiments, transmitting the sidelink HARQ feedback according to the indicated timing based at least on the priority of the sidelink data may include transmitting the sidelink HARQ feedback according to the indicated timing based at least in part on the priority of the sidelink data being higher than the predetermined threshold. 
     In some embodiments, determining the priority of the sidelink data includes comparing the priority of the sidelink data to a priority of the second transmission or a priority associated with the second transmission. In these embodiments, transmitting the sidelink HARQ feedback according to the indicated timing based at least on the priority of the sidelink data includes transmitting the sidelink HARQ feedback according to the indicated timing based at least in part on determining that the priority of the sidelink data is higher than the priority of the second transmission. 
     In some embodiments, it may be determined that the sidelink data associated with the sidelink HARQ feedback has a same priority class as the second transmission. In these embodiments, transmitting the sidelink HARQ feedback according to the indicated timing may include piggybacking the sidelink HARQ feedback with the second transmission. 
     In other embodiments, based on a determination that the sidelink data has a lower priority than the second transmission, the wireless device may refrain from transmitting the sidelink HARQ feedback according to the indicated timing. In these embodiments, the wireless device may transmit the second transmission according to its scheduled timing, and may cancel the sidelink HARQ feedback, or alternatively the wireless device may postpone the sidelink HARQ feedback until a future available opportunity. 
     A further exemplary embodiment may include a method, comprising: performing, by a wireless device, any or all parts of the preceding examples. 
     Another exemplary embodiment may include a device, comprising: an antenna; a radio coupled to the antenna; and a processing element operably coupled to the radio, wherein the device is configured to implement any or all parts of the preceding examples. 
     A further exemplary set of embodiments may include a non-transitory computer accessible memory medium comprising program instructions which, when executed at a device, cause the device to implement any or all parts of any of the preceding examples. 
     A still further exemplary set of embodiments may include a computer program comprising instructions for performing any or all parts of any of the preceding examples. 
     Yet another exemplary set of embodiments may include an apparatus comprising means for performing any or all of the elements of any of the preceding examples. 
     Still another exemplary set of embodiments may include an apparatus comprising a processing element configured to cause a wireless device to perform any or all of the elements of any of the preceding examples. 
     As described above, one aspect of the present technology is the gathering and use of data available from specific and legitimate sources to improve coordination of traffic flow in traffic environments. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to identify a specific person. Such personal information data can include demographic data, location-based data, online identifiers, telephone numbers, email addresses, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data may be used to better harmonize traffic flow in the user&#39;s environment, such that transportation of the user and other users becomes more efficient. Further, the personal data may improve safety of the user (and other users) by averting traffic accidents, particularly vehicular collisions. For example, in the case of a pedestrian user, the personal information, particularly movement- and position-related information, may operate to avert potentially fatal collisions between vehicles and the user. Also, the personal information may be usable to reduce resource and power consumption by user devices benefitting from traffic-related networks, which may improve users&#39; experiences. 
     The present disclosure contemplates that those entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities would be expected to implement and consistently apply privacy practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. Such information regarding the use of personal data should be prominent and easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate uses only. Further, such collection/sharing should occur only after receiving the consent of the users or other legitimate basis specified in applicable law. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations that may serve to impose a higher standard. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data for use in vehicle- and transportation-related networks. In another example, users can select not to provide certain personal data, such as location or movement data, to V2X networks for traffic safety and coordination purposes. In yet another example, users may be able to select to limit the length of time or degree to which traffic-associated data is maintained or entirely block the development of a baseline traffic or vehicle profile. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified that their personal information data will be accessed for use in vehicle and transportation networks. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing identifiers, controlling the amount or specificity of data stored (e.g., collecting location data at city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods such as differential privacy. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users based on aggregated non-personal information data or a bare minimum amount of personal information, such as the content being handled only on the user&#39;s device or other non-personal information available to the content delivery services 
     Embodiments of the present disclosure may be realized in any of various forms. For example, some embodiments may be realized as a computer-implemented method, a computer-readable memory medium, or a computer system. Other embodiments may be realized using one or more custom-designed hardware devices such as ASICs. Still other embodiments may be realized using one or more programmable hardware elements such as FPGAs. 
     In some embodiments, a non-transitory computer-readable memory medium may be configured so that it stores program instructions and/or data, where the program instructions, if executed by a computer system, cause the computer system to perform a method, e.g., any of a method embodiments described herein, or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets. 
     In some embodiments, a device (e.g., a UE  104 ) may be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets). The device may be realized in any of various forms. 
     Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.