WO2022018587A1

WO2022018587A1 - Radio resource control inactive state sidelink communications

Info

Publication number: WO2022018587A1
Application number: PCT/IB2021/056416
Authority: WO
Inventors: Prateek Basu Mallick; Karthikeyan Ganesan; Ravi Kuchibhotla
Original assignee: Lenovo (Singapore) Pte. Ltd.
Priority date: 2020-07-22
Filing date: 2021-07-15
Publication date: 2022-01-27

Abstract

Apparatuses, methods, and systems are disclosed for radio resource control inactive state sidelink communications. One method (500) includes entering (502), at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. The method (500) includes receiving (504) mode one resources for sidelink transmissions. The method (500) includes transmitting (506), from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

Description

RADIO RESOURCE CONTROL INACTIVE STATE SIDELINE COMMUNICATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States Patent Application Serial Number 63/055,202 entitled “APPARATUSES, METHODS, AND SYSTEMS FOR SIDELINE OPERATION IN RRC INACTIVE STATE” and filed on July 22, 2020 for Prateek Basu Mallick, which is incorporated herein by reference in its entirety.

FIELD

[0002] The subject matter disclosed herein relates generally to wireless communications and more particularly relates to radio resource control inactive state sidelink communications.

BACEGROUND

[0003] In certain wireless communications networks, resources may be used inefficiently if a mobile device operates continually in a connected state. However, mobile communication is limited in an inactive state.

BRIEF SUMMARY

[0004] Methods for radio resource control inactive state sidelink communications are disclosed. Apparatuses and systems also perform the functions of the methods. One embodiment of a method includes entering, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. In some embodiments, the method includes receiving mode one resources for sidelink transmissions. In certain embodiments, the method includes transmitting, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

[0005] One apparatus for radio resource control inactive state sidelink communications includes a first user equipment. In some embodiments, the apparatus includes a processor that enters a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. In various embodiments, the apparatus includes a receiver that receives mode one resources for sidelink transmissions. In certain embodiments, the apparatus includes a transmitter that transmits, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

[0006] Another embodiment of a method for radio resource control inactive state sidelink communications includes transmitting, from a radio network node in a serving cell, a radio resource control release message to cause a user equipment to enter a radio resource control inactive state. In some embodiments, the method includes transmitting mode one resources for sidelink transmissions. The user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state.

[0007] Another apparatus for radio resource control inactive state sidelink communications includes a radio network node in a serving cell. In some embodiments, the apparatus includes a transmitter that: transmits a radio resource control release message to cause a user equipment to enter a radio resource control inactive state; and transmits mode one resources for sidelink transmissions. The user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 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:

[0009] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for radio resource control inactive state sidelink communications;

[0010] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for radio resource control inactive state sidelink communications;

[0011] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for radio resource control inactive state sidelink communications;

[0012] Figure 4 is a flow chart diagram illustrating one embodiment of a method for performing sidelink transmission in an RRC inactive state;

[0013] Figure 5 is a flow chart diagram illustrating one embodiment of a method for radio resource control inactive state sidelink communications; and

[0014] Figure 6 is a flow chart diagram illustrating another embodiment of a method for radio resource control inactive state sidelink communications.

DETAIFED DESCRIPTION

[0015] 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 that may all generally be referred to herein as a “circuit,” “module” or “system.” 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 hi a certain embodiment, the storage devices only employ signals for accessing code.

[0016] Certain of the functional units described in this specification may be labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSF’) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[0017] Modules may also be implemented in code and/or software for execution by various types of processors. An identified module of code may, for instance, include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may include disparate instructions stored in different locations which, when joined logically together, include the module and achieve the stated purpose for the module.

[0018] Indeed, a module of code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different computer readable storage devices. Where a module or portions of a module are implemented in software, the software portions are stored on one or more computer readable storage devices.

[0019] 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.

[0020] 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.

[0021] 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's computer, partly on the user's computer, as a stand-alone software package, partly on the user'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's computer through any type of network, including a local area network (“LAN”) 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).

[0022] 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.

[0023] 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.

[0024] 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. The 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 schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0025] 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 schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0026] 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 and/or block diagram block or blocks.

[0027] The schematic flowchart diagrams and/or schematic 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 schematic flowchart diagrams and/or schematic 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).

[0028] 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.

[0029] Although various arrow types and line types may be employed in the 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.

[0030] 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.

[0031] Figure 1 depicts an embodiment of a wireless communication system 100 for radio resource control inactive state sidelink communications. In one embodiment, the wireless communication system 100 includes remote units 102 and network units 104. Even though a specific number of remote units 102 and network units 104 are depicted in Figure 1, one of skill in the art will recognize that any number of remote units 102 and network units 104 may be included in the wireless communication system 100.

[0032] In one embodiment, the remote units 102 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), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), aerial vehicles, drones, or the like. In some embodiments, the remote units 102 include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units 102 may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, UE, user terminals, a device, or by other terminology used in the art. The remote units 102 may communicate directly with one or more of the network units 104 via UL communication signals. In certain embodiments, the remote units 102 may communicate directly with other remote units 102 via sidelink communication.

[0033] The network units 104 may be distributed over a geographic region. In certain embodiments, a network unit 104 may also be referred to and/or may include one or more of an access point, an access terminal, a base, a base station, a location server, a core network (“CN”), a radio network entity, a Node-B, an evolved node-B (“eNB”), a 5G node-B (“gNB”), a Home Node-B, a relay node, a device, a core network, an aerial server, a radio access node, an access point (“AP”), new radio (“NR”), a network entity, an access and mobility management function (“AMF”), a unified data management (“UDM”), a unified data repository (“UDR”), a UDM/UDR, a policy control function (“PCF”), a radio access network (“RAN”), a network slice selection function (“NSSF”), an operations, administration, and management (“OAM”), a session management function (“SMF”), a user plane function (“UPF”), an application function, an authentication server function (“AUSF”), security anchor functionality (“SEAF”), trusted non- 3GPP gateway function (“TNGF”), or by any other terminology used in the art. The network units 104 are generally part of a radio access network that includes one or more controllers communicably coupled to one or more corresponding network units 104. The radio access network is generally communicably coupled to one or more core networks, which may be coupled to other networks, like the Internet and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art.

[0034] In one implementation, the wireless communication system 100 is compliant with NR protocols standardized in third generation partnership project (“3GPP”), wherein the network unit 104 transmits using an OFDM modulation scheme on the downlink (“DL”) and the remote units 102 transmit on the uplink (“UL”) using a single-carrier frequency division multiple access (“SC-FDMA”) scheme or an orthogonal frequency division multiplexing (“OFDM”) scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocol, for example, WiMAX, institute of electrical and electronics engineers (“IEEE”) 802.11 variants, global system for mobile communications (“GSM”), general packet radio service (“GPRS”), universal mobile telecommunications system (“UMTS”), long term evolution (“LTE”) variants, code division multiple access 2000 (“CDMA2000”), Bluetooth®, ZigBee, Sigfoxx, among other protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0035] The network units 104 may serve a number of remote units 102 within a serving area, for example, a cell or a cell sector via a wireless communication link. The network units 104 transmit DL communication signals to serve the remote units 102 in the time, frequency, and/or spatial domain. [0036] In various embodiments, a remote unit 102 may enter, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. In some embodiments, the remote unit 102 may receive mode one resources for sidelink transmissions. In certain embodiments, the remote unit 102 may transmit, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state. Accordingly, the remote unit 102 may be used for radio resource control inactive state sidelink communications.

[0037] In certain embodiments, a network unit 104 may transmit, from a radio network node in a serving cell, a radio resource control release message to cause a user equipment to enter a radio resource control inactive state. In some embodiments, the network unit 104 may transmit mode one resources for sidelink transmissions. The user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state. Accordingly, the network unit 104 may be used for radio resource control inactive state sidelink communications.

[0038] Figure 2 depicts one embodiment of an apparatus 200 that may be used for radio resource control inactive state sidelink communications. The apparatus 200 includes one embodiment of the remote unit 102. Furthermore, the remote unit 102 may include a processor 202, a memory 204, an input device 206, a display 208, a transmitter 210, and a receiver 212. In some embodiments, the input device 206 and the display 208 are combined into a single device, such as a touchscreen. In certain embodiments, the remote unit 102 may not include any input device 206 and/or display 208. In various embodiments, the remote unit 102 may include one or more of the processor 202, the memory 204, the transmitter 210, and the receiver 212, and may not include the input device 206 and/or the display 208.

[0039] The processor 202, 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 202 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 202 executes instructions stored in the memory 204 to perform the methods and routines described herein. The processor 202 is communicatively coupled to the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212.

[0040] The memory 204, in one embodiment, is a computer readable storage medium. In some embodiments, the memory 204 includes volatile computer storage media. For example, the memory 204 may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory 204 includes non-volatile computer storage media. For example, the memory 204 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 204 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 204 also stores program code and related data, such as an operating system or other controller algorithms operating on the remote unit 102.

[0041] The input device 206, 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 206 may be integrated with the display 208, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device 206 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 206 includes two or more different devices, such as a keyboard and a touch panel.

[0042] The display 208, in one embodiment, may include any known electronically controllable display or display device. The display 208 may be designed to output visual, audible, and/or haptic signals. In some embodiments, the display 208 includes an electronic display capable of outputting visual data to a user. For example, the display 208 may include, but is not limited to, a liquid crystal display (“LCD”), a light emitting diode (“LED”) display, an organic light emitting diode (“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 display 208 may include a wearable display such as a smart watch, smart glasses, a heads-up display, or the like. Further, the display 208 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.

[0043] In certain embodiments, the display 208 includes one or more speakers for producing sound. For example, the display 208 may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the display 208 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the display 208 may be integrated with the input device 206. For example, the input device 206 and display 208 may form a touchscreen or similar touch-sensitive display. In other embodiments, the display 208 may be located near the input device 206.

[0044] In some embodiments, the processor 202 enters a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. In various embodiments, the receiver 212 receives mode one resources for sidelink transmissions. In certain embodiments, the transmitter 210 transmits, from a first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

[0045] Although only one transmitter 210 and one receiver 212 are illustrated, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and the receiver 212 may be any suitable type of transmitters and receivers. In one embodiment, the transmitter 210 and the receiver 212 may be part of a transceiver.

[0046] Figure 3 depicts one embodiment of an apparatus 300 that may be used for radio resource control inactive state sidelink communications. The apparatus 300 includes one embodiment of the network unit 104. Furthermore, the network unit 104 may include a processor 302, a memory 304, an input device 306, a display 308, a transmitter 310, and a receiver 312. As may be appreciated, the processor 302, the memory 304, the input device 306, the display 308, the transmitter 310, and the receiver 312 may be substantially similar to the processor 202, the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212 of the remote unit 102, respectively.

[0047] In certain embodiments, the transmitter 310: transmits a radio resource control release message to cause a user equipment to enter a radio resource control inactive state; and transmits mode one resources for sidelink transmissions. The user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state.

[0048] In some embodiments, power saving enables user equipments (“UEs”) with battery constraint to perform sidelink operations in a power efficient manner. In various embodiments, sidelink is based on the assumption of “always-on” (e.g., only focusing on UEs installed in vehicles with sufficient battery capacity). In certain embodiments, power saving may be used for vulnerable road users (“VRUs”) in vehicle to everything (“V2X”) configurations and for UEs in public safety and commercial use configurations where power consumption in the UEs needs to be minimized.

[0049] In various embodiments, power saving for a UE may be performed by enabling the UE to operate sidelink communications while in a radio resource control (“RRC”) inactive state on a network to UE (“Uu”) interface.

[0050] In a first embodiment, power saving may be accomplished by having a UE in an RRC inactive state instead of an RRC connected state if a network would like the UE to use new radio (“NR”) mode 1 (e.g., network provided) based sidelink grants. [0051] In a first implementation of the first embodiment, while in an RRC inactive state, a sidelink (“SL”) UE performs only SL reception and no SL transmission. In such embodiments, to send transmissions via sidelink, the UE may initiate a transition to an RRC connected state and then seek mode 1 SL resources from a gNB. An “RRC resume cause” may be used to indicate that the transition to the RRC connected state is for the purpose of seeking mode 1 SL transmission resources.

[0052] In such an embodiment, requesting SL resources may be done by transmitting a SL buffer status report (“BSR”) together with a random access channel (“RACH”) procedure to initiate transition to an RRC connected state for example, a 2-step RACH procedure may be used to transmit the BSR (e.g., together with a UE identity for contention resolution) as part of a message A (“MsgA”). In a 4-step RACH procedure, this may be accomplished using message 3 (“Msg 3”).

[0053] In a second implementation of the first embodiment, an RRC inactive state SL UE may perform SL reception as well as transmission while in the RRC inactive state for SL transmission resources, a configured grant (e.g., typel, type2) may be allocated by a gNB while the UE is in an RRC connected state (e.g., in an RRC release message sending the UE to the RRC inactive state), or in an earlier reconfiguration message. The UE uses only the configured grants for any SL related transmission and/or retransmissions. Unlike while a UE is in an RRC connected state, while in the RRC inactive state, the retransmissions are handled by a TX UE using a next available CG opportunity or mode 2 (e.g., dynamic scheduling is used by the UE). In this implementation, the configured grant can be configured as follows: 1) valid only in a serving cell where the UE is sent to the RRC inactive state for atime period of up to t380 (e.g., PeriodicRNAU- TimerValue) and/or a new timer configured while the UE is in the RRC connected state; 2) valid only in a serving cell where the UE is sent to the RRC inactive state and some other cells for a time period of up to t380 (e.g., PeriodicRNAU-TimerValue) and/or a new timer - the “some other cells” and the timer may be configured while the UE is in the RRC connected state; and/or 3) valid in the entire RAN-NotificationArealnfo for a time period of up to t380 (e.g., PeriodicRNAU- TimerValue) or a new timer configured while the UE is in the RRC connected state.

[0054] For the second implementation of the first embodiment, this kind of configuration may be sensible if the UE does not transmit much (e.g., basic safety messages, virtual antenna mapping (“VAM”), VRU awareness messages once per seconds, or forth) on sidelink and has no Uu data to send or receive. The UE may, before the expiration of a timer, announce to the gNB that SL transmission resources are no longer required by sending suitable signaling while in the RRC inactive state (e.g., using MsgA or Msg3) or upon transitioning to the RRC connected state using UE assistance information (“UAI”) or sidelink UE information (“SUE’). The gNB may take away the configured grants or may reconfigure the configured grants by initiating radio access network (“RAN”) paging to the UE, asking the UE to transition to the RRC connected state and then sending the UE a RRC reconfiguration message.

[0055] In any embodiments, the UE may use a new RRC resume cause to let a network know that a state transition is initiated for sidelink related purposes.

[0056] Figure 4 is a flow chart diagram illustrating one embodiment of a method 400 for performing sidelink transmission in an RRC inactive state. A UE starts 402 in an RRC connected state. The UE receives 406 an RRC release (e.g., including a SL-CGConfig for an RRC inactive state for cell 1 & 2). The UE transitions 410 to an RRC inactive state and starts atimer (e.g., timer t380). In some embodiments, the timer may be started as soon as an RRC release message is received or once a transition from an RRC connected state is started. A SL message arrives 414 in a layer 2 (“L2”) buffer. The UE determines 418 whether the timer is still running. If the timer is not still running, the UE uses 422 mode 2 SL resources or initiates a transition to an RRC connected state. If the timer is still running, the UE determines 428 if it is still in cell 1 or cell 2. If the UE is not still in cell 1 or cell 2, the UE uses 422 mode 2 SL resources or initiates a transition to the RRC connected state. If the UE is still in cell 1 or cell 2, the UE uses 432 a configured grant (“CG”) to transmit a SL message. Then the method 400 ends 436.

[0057] In a second embodiment, instead of initiating a transition to an RRC connected state, a UE may be kept in an RRC inactive state while allowing signaling of dedicated DL messages (e.g., physical downlink control channel (“PDCCH”)), and the dedicated DL messages (e.g., PDCCH) may configure the UE with mode 1 configured grant resources. Accordingly, the UE may monitor only DCI 3 0 in the RRC inactive state using at least a last (or first) 16 digits of a full inactive (“I”) radio network temporary identifier (“RNTI”) (“I-RNTI”) or a short I-RNTI. In some embodiments, a cell (“C”) RNTI (“C-RNTI”) of a UE from an RRC connected state may continue to be used if allowed by an RRC release message. This may be applicable in a limited area scope and for a limited time period. The area scope and time period may be signaled to the UE while in the UE is in the RRC connected state. If not signaled, a default value may be used, but a network may explicitly indicate to the RRC connected state UE whether the network would like the UE to monitor DCI 3 0 (or a similar DCI) in the RRC inactive state. Any RRC connected messages may be used for such a network indication (e.g., including RRC reconfiguration).

[0058] In a third embodiment, an indication (e.g., discontinuous transmission (“DTX”) or a hybrid automatic repeat request (“HARQ”) acknowledgment (“ACK”)) may be sent by a transmit ( TX ) UE on a physical uplink control channel (“PUCCH”) corresponding to a mode 1 grant to a gNB even if there would be a retransmission required on sidelink. The indication tells the gNB that no mode 1 retransmission resources are required. If a retransmission is required on sidelink, as a blind retransmission or a HARQ feedback-based retransmission, the TX UE switches to mode 2 (e.g., UE autonomously selecting transmission resources) to save PUCCH transmission power. This may be useful if the UE is about to enter Uu DRX-sleep. The UE may not restart a DRX inactivity timer upon receiving a grant. The gNB may assume that a transport block (“TB”) is successfully transmitted if it receives a DTX or a HARQ ACK.

[0059] In certain configurations of the third embodiment, the PUCCH resources are not provided corresponding to a mode 1 sidelink grant, instead the TX UE is expected to either: 1) switch to mode 2 based retransmissions, if any retransmission is required to be made; or 2) use the next available opportunity of a sidelink configured grant (e.g., SL-ConfiguredGrantConfig of a SL-ConfiguredGrantConfig) with same or different index (e.g., sl-ConfiglndexCG).

[0060] Figure 5 is a flow chart diagram illustrating one embodiment of a method 500 for radio resource control inactive state sidelink communications. In some embodiments, the method 500 is performed by an apparatus, such as the remote unit 102. In certain embodiments, the method

500 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0061] In various embodiments, the method 500 includes entering 502, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell. In some embodiments, the method 500 includes receiving 504 mode one resources for sidelink transmissions. In certain embodiments, the method 500 includes transmitting 506, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state. [0062] In certain embodiments, the method 500 further comprises performing sidelink reception using preconfigured resources or using resource pool information received from broadcast system information. In some embodiments, the mode one resources for sidelink transmission are received in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel. In various embodiments, the mode one resources comprise mode one resources corresponding to a configured grant.

[0063] In one embodiment, the configured grant applies to sidelink transmissions and any re-transmissions. In certain embodiments, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof. In some embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

[0064] In various embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof. In one embodiment, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message. In certain embodiments, the method 500 further comprises receiving dynamic resource grants from the radio network node based on results from monitoring a dedicated downlink control message in the radio resource control inactive state. [0065] In some embodiments, the method 500 further comprises receiving the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier. In various embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state. In one embodiment, the method 500 further comprises transmitting an indication to the radio network node indicating that no mode one retransmission resources are required.

[0066] In certain embodiments, the indication comprises a discontinuous transmission or a feedback acknowledgement. In some embodiments, the method 500 further comprises transitioning to mode two to perform a retransmission. In various embodiments, the mode two resources are resources selected by the first user equipment from a pool of radio resources configured by the radio network node.

[0067] Figure 6 is a flow chart diagram illustrating another embodiment of a method 600 for radio resource control inactive state sidelink communications. In some embodiments, the method 600 is performed by an apparatus, such as the network unit 104. In certain embodiments, the method 600 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0068] In various embodiments, the method 600 includes transmitting 602, from a radio network node in a serving cell, a radio resource control release message to cause a user equipment to enter a radio resource control inactive state. In some embodiments, the method 600 includes transmitting 604 mode one resources for sidelink transmissions. The user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state. [0069] In certain embodiments, the mode one resources for sidelink transmission are transmitted in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel. In some embodiments, the mode one resources comprise mode one resources corresponding to a configured grant. In various embodiments, the configured grant applies to sidelink transmissions and any re transmissions.

[0070] In one embodiment, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof. In certain embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message. In some embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof.

[0071] In various embodiments, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message. In one embodiment, the method 600 further comprises transmitting dynamic resource grants from the radio network node. In certain embodiments, the method 600 further comprises transmitting the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

[0072] In some embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state. In various embodiments, the method 600 further comprises receiving an indication at the radio network node indicating that no mode one retransmission resources are required. In one embodiment, the indication comprises a discontinuous transmission or a feedback acknowledgement.

[0073] In one embodiment, a method comprises: entering, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell; receiving mode one resources for sidelink transmissions; and transmitting, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

[0074] In certain embodiments, the method further comprises performing sidelink reception using preconfigured resources or using resource pool information received from broadcast system information. [0075] In some embodiments, the mode one resources for si delink transmission are received in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel.

[0076] In various embodiments, the mode one resources comprise mode one resources corresponding to a configured grant.

[0077] In one embodiment, the configured grant applies to sidelink transmissions and any re-transmissions.

[0078] In certain embodiments, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof. [0079] In some embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

[0080] In various embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof. [0081] In one embodiment, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message.

[0082] In certain embodiments, the method further comprises receiving dynamic resource grants from the radio network node based on results from monitoring a dedicated downlink control message in the radio resource control inactive state. [0083] In some embodiments, the method further comprises receiving the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

[0084] In various embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state.

[0085] In one embodiment, the method further comprises transmitting an indication to the radio network node indicating that no mode one retransmission resources are required.

[0086] In certain embodiments, the indication comprises a discontinuous transmission or a feedback acknowledgement.

[0087] In some embodiments, the method further comprises transitioning to mode two to perform a retransmission.

[0088] In various embodiments, the mode two resources are resources selected by the first user equipment from a pool of radio resources configured by the radio network node. [0089] In one embodiment, an apparatus comprises: a processor that enters, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell; a receiver that receives mode one resources for sidelink transmissions; and a transmitter that transmits, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

[0090] In certain embodiments, the processor performs sidelink reception using preconfigured resources or using resource pool information received from broadcast system information. [0091] In some embodiments, the mode one resources for sidelink transmission are received in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel.

[0092] In various embodiments, the mode one resources comprise mode one resources corresponding to a configured grant. [0093] In one embodiment, the configured grant applies to sidelink transmissions and any re-transmissions.

[0094] In certain embodiments, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof.

[0095] In some embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

[0096] In various embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof.

[0097] In one embodiment, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message.

[0098] In certain embodiments, the receiver receives dynamic resource grants from the radio network node based on results from monitoring a dedicated downlink control message in the radio resource control inactive state.

[0099] In some embodiments, the receiver receives the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

[0100] In various embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state.

[0101] In one embodiment, the transmitter transmits an indication to the radio network node indicating that no mode one retransmission resources are required.

[0102] In certain embodiments, the indication comprises a discontinuous transmission or a feedback acknowledgement.

[0103] In some embodiments, the processor transitions to mode two to perform a retransmission.

[0104] In various embodiments, the mode two resources are resources selected by the first user equipment from a pool of radio resources configured by the radio network node.

[0105] In one embodiment, a method comprises: transmitting, from a radio network node in a serving cell, a radio resource control release message to cause a user equipment to enter a radio resource control inactive state; and transmitting mode one resources for sidelink transmissions, wherein the user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state.

[0106] In certain embodiments, the mode one resources for sidelink transmission are transmitted in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel.

[0107] In some embodiments, the mode one resources comprise mode one resources corresponding to a configured grant.

[0108] In various embodiments, the configured grant applies to sidelink transmissions and any re-transmissions.

[0109] In one embodiment, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof.

[0110] In certain embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

[0111] In some embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof.

[0112] In various embodiments, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message.

[0113] In one embodiment, the method further comprises transmitting dynamic resource grants from the radio network node. [0114] In certain embodiments, the method further comprises transmitting the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

[0115] In some embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state.

[0116] In various embodiments, the method further comprises receiving an indication at the radio network node indicating that no mode one retransmission resources are required. [0117] In one embodiment, the indication comprises a discontinuous transmission or a feedback acknowledgement.

[0118] In one embodiment, an apparatus comprises a radio network node in a serving cell. The apparatus further comprises: a transmitter that: transmits a radio resource control release message to cause a user equipment to enter a radio resource control inactive state; and transmits mode one resources for sidelink transmissions, wherein the user equipment transmits sidelink communications based on the mode one resources while the user equipment is in the radio resource control inactive state.

[0119] In certain embodiments, the mode one resources for sidelink transmission are transmitted in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel.

[0120] In some embodiments, the mode one resources comprise mode one resources corresponding to a configured grant.

[0121] In various embodiments, the configured grant applies to sidelink transmissions and any re-transmissions. [0122] In one embodiment, the configured grant is valid only in a limited area, for a limited time period, or a combination thereof.

[0123] In certain embodiments, the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

[0124] In some embodiments, the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof.

[0125] In various embodiments, the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message. [0126] In one embodiment, the transmitter transmits dynamic resource grants from the radio network node.

[0127] In certain embodiments, the transmitter transmits the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

[0128] In some embodiments, the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state. [0129] In various embodiments, the apparatus further comprises a receiver that receives an indication at the radio network node indicating that no mode one retransmission resources are required.

[0130] In one embodiment, the indication comprises a discontinuous transmission or a feedback acknowledgement. [0131] 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.

Claims

1 An apparatus comprising: a processor that enters, at a first user equipment, a radio resource control inactive state in response to receiving a radio resource control release message from a radio network node in a serving cell; a receiver that receives mode one resources for sidelink transmissions; and a transmitter that transmits, from the first user equipment to a second user equipment, sidelink communications based on the mode one resources while the first user equipment is in the radio resource control inactive state.

2 The apparatus of claim 1, wherein the processor performs sidelink reception using preconfigured resources or using resource pool information received from broadcast system information.

3. The apparatus of claim 1, wherein the mode one resources for sidelink transmission are received in the radio resource control release message and use of the mode one resources in the radio resource control inactive state are triggered by a physical downlink control channel.

4. The apparatus of claim 3, wherein the mode one resources comprise mode one resources corresponding to a configured grant.

5. The apparatus of claim 4, wherein the configured grant applies to sidelink transmissions and any re-transmissions.

6 The apparatus of claim 4, wherein the configured grant is valid only in a limited area, for a limited time period, or a combination thereof.

7 The apparatus of claim 4, wherein the configured grant is valid only in a limited area, and the limited area is signaled in the radio resource control release message.

8. The apparatus of claim 7, wherein the limited area comprises the serving cell, at least one neighbor cell, a radio access network notification area, a part of the radio access network notification area, or some combination thereof.

9. The apparatus of claim 4, wherein the configured grant is valid only for a limited time period, and the time period is set to a timer signaled in the radio resource control release message.

10. The apparatus of claim 1, wherein the receiver receives dynamic resource grants from the radio network node based on results from monitoring a dedicated downlink control message in the radio resource control inactive state.

11. The apparatus of claim 10, wherein the receiver receives the dedicated downlink control message using at least 16 digits of a full inactive radio network temporary identifier or a short inactive radio network temporary identifier.

12 The apparatus of claim 10, wherein the dedicated dynamic resource grant is valid only in a limited area, for a limited time period, or a combination thereof, and the limited area, the limited time period, or the combination thereof are signaled while in the first user equipment is in a radio resource control connected state.

13. The apparatus of claim 1, wherein the transmitter transmits an indication to the radio network node indicating that no mode one retransmission resources are required.

14. The apparatus of claim 13, wherein the indication comprises a discontinuous transmission or a feedback acknowledgement.

15 The apparatus of claim 13, wherein the processor transitions to mode two to perform a retransmission.