Radio Resource Control Connection Procedure of Remote Wireless Device

Abstract

The present disclosure relates to a radio resource control connection process of a remote wireless device. Specifically, it relates to a method, including: by a relay wireless device: relaying radio resource control (RRC) messages between a cellular base station and a remote wireless device to establish an RRC connection with the cellular base station; determining a radio link failure in the Uu link; transmitting an indication of the radio link failure in the Uu link to the remote wireless device so that the remote wireless device performs RRC reconstruction.

Description

[0001] This application is a divisional application of the invention patent application with the application date of August 13, 2019, the application number of 201910746189.1, and the title of "Radio Resource Control Connection Process of Remote Wireless Devices". Technical Field

[0002] This patent application relates to wireless communication, including the radio resource control connection process of remote wireless devices in a wireless communication system. Background Art

[0003] The use of wireless communication systems is growing rapidly. Additionally, wireless communication technology has evolved from voice - only communication to also include the transmission of data such as Internet and multimedia content.

[0004] Mobile electronic devices can take the form of smart phones or tablets that users typically carry. Wearable devices (also known as accessory devices) are a newer form of mobile electronic device, an example being a smart watch. Additionally, low - cost and low - complexity wireless devices intended for static or dynamic deployment are also increasing rapidly as part of the development of the "Internet of Things". In other words, the range of complexities, capabilities, traffic patterns, and other characteristics of the required devices is becoming increasingly broad. Generally speaking, it should be desirable to recognize and provide improved support for a wide range of required wireless communication characteristics. Therefore, improvements in this field are desired. Summary of the Invention

[0005] Embodiments of systems, apparatuses, and methods are presented herein, particularly for performing radio resource control connection processes for remote wireless devices in a wireless communication system.

[0006] As described above, the number of use cases for different types of wireless devices with widely varying capabilities and usage expectations is increasing. One direction of the expansion of possible use cases supported by wireless communication technology can include towards low - cost and / or low - power wireless devices. The ability to support such wireless devices in establishing radio resource control connections and obtaining access to a cellular network through an intermediate relay wireless device can increase the practicality of such low - cost and / or low - power wireless devices.

[0007] Therefore, the techniques described herein include techniques for: a remote wireless device providing an RRC message relayed to a cellular base station to a relay wireless device; a cellular base station providing an RRC message relayed to the remote wireless device to the relay wireless device; and the relay wireless device relaying such messages between the cellular base station and the remote wireless device.

[0008] In addition, the techniques described herein include techniques for combining remote radio resource control connection detection of link failures and link failure handling, where both link failure detection and link failure handling are for wireless links between a remote wireless device and a relay wireless device, and also for wireless links between a relay wireless device and a cellular base station.

[0009] The techniques described herein can be implemented in and / or used with several different types of devices, including but not limited to any one of a cellular phone, a tablet computer, an accessory and / or wearable computing device, a portable media player, a cellular base station and other cellular network infrastructure devices, a server, and various other computing devices.

[0010] This summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it should be understood that the above features are merely examples and should not be construed as narrowing the scope or essence 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, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A better understanding of the subject matter can be obtained when the following detailed description of the embodiments is considered in conjunction with the following drawings.

[0012] Figure 1 An exemplary wireless communication system including an accessory device is shown in accordance with some embodiments;

[0013] Figure 2 An exemplary wireless communication system in which two wireless devices are capable of performing direct device-to-device communication is shown in accordance with some embodiments;

[0014] Figure 3 is a block diagram of an exemplary wireless device shown in accordance with some embodiments;

[0015] Figure 4 is a block diagram of an exemplary base station shown in accordance with some embodiments;

[0016] Figure 5 is a communication flow diagram of an exemplary method for performing presence discovery in a wireless communication system shown in accordance with some embodiments;

[0017] Figure 6 Aspects of possible wireless communication relaying between a remote UE, a relay UE, and a gNB are shown in accordance with some embodiments;

[0018] Figures 7 to 8Illustrates exemplary aspects of a possible protocol stack architecture for user plane and control plane communications in a 3GPP-based UE-to-network relay framework according to some embodiments;

[0019] Figure 9 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where multiple remote UEs attempt to establish an RRC connection with a gNB via the same relay UE;

[0020] Figure 10 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a single remote UE attempts to establish an RRC connection with a gNB via a relay UE;

[0021] Figure 11 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a single remote UE attempts to re - establish an RRC connection with a gNB via a relay UE;

[0022] Figure 12 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a single remote UE attempts to resume an RRC connection with a gNB via a relay UE;

[0023] Figure 13 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where the gNB releases the remote RRC connection with a remote UE via a relay UE;

[0024] Figure 14 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where the gNB reconfigures the remote RRC connection with a remote UE via a relay UE;

[0025] Figure 15 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where the establishment of a remote RRC connection fails due to a link failure between the relay UE and the gNB;

[0026] Figure 16 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where the re - establishment of a remote RRC connection fails due to a link failure between the relay UE and the gNB;

[0027] Figure 17 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where the resumption of a remote RRC connection fails due to a link failure between the relay UE and the gNB;

[0028] Figure 18is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a relay UE uses a response validity timer to detect a link failure between the relay UE and a remote UE;

[0029] Figure 19 is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a relay UE uses a response validity timer to detect a PC5 interface failure between the relay UE and a remote UE;

[0030] Figure 20 is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where for a link failure between a remote UE and a relay UE, the remote UE uses a response guard timer;

[0031] Figure 21 is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a remote RRC connection establishment fails due to a link failure between a relay UE and a remote UE;

[0032] Figure 22 is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a remote RRC connection re - establishment fails due to a link failure between a relay UE and a remote UE; and

[0033] Figure 23 is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a remote RRC connection recovery fails due to a link failure between a relay UE and a remote UE.

[0034] Although the features described herein are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are described in detail herein. However, it should be understood that the drawings and the detailed description thereof are not intended to limit the present disclosure to the specific forms 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

[0035] Acronyms

[0036] The following acronyms are used in this disclosure.

[0037] 3GPP: Third Generation Partnership Project

[0038] 3GPP2: Third Generation Partnership Project 2

[0039] GSM: Global System for Mobile Communications

[0040] UMTS: Universal Mobile Telecommunications System

[0041] LTE: Long Term Evolution

[0042] IoT: Internet of Things

[0043] NB: Narrow Band

[0044] D2D: Device-to-Device

[0045] OOC: Out of Coverage

[0046] Terminology

[0047] The following are definitions of terms used in this disclosure:

[0048] Memory medium - Any of various types of non-transitory memory devices or storage devices. The term "memory medium" is intended to include installation media such as CD-ROMs, floppy disks, or magnetic tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media such as hard disk drives or optical storage devices; registers, or other similar types of memory elements, etc. The memory medium may also include other types of non-transitory memory or combinations thereof. In addition, the memory medium may be located in a first computer system that executes a program, or may be located in a different second computer system that is connected to the first computer system via a network such as the Internet. In the latter case, the second computer system may provide program instructions to the first computer for execution. The term "memory medium" may include two or more memory media that may reside at different locations in different computer systems connected, for example, via a network. The memory medium may store program instructions (e.g., embodied as a computer program) executable by one or more processors.

[0049] Carrier medium - The memory medium as described above, as well as physical transmission media such as buses, networks, and / or other physical transmission media that convey signals such as electrical, electromagnetic, or digital signals.

[0050] Programmable hardware element - Includes various hardware devices that include multiple programmable function blocks connected via programmable interconnects. Examples include FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field Programmable Object Arrays), and CPLDs (Complex PLDs). The programmable function blocks can vary from fine-grained (combinational logic components or look-up tables) to coarse-grained (arithmetic logic units or processor cores). Programmable hardware elements may also be referred to as "configurable logic components".

[0051] Computer system - Any of various types of computing or processing systems, including personal computer systems (PCs), mainframe computer systems, workstations, network devices, Internet devices, personal digital assistants (PDAs), television systems, grid computing systems, or other devices or combinations of devices. Generally speaking, 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.

[0052] User Equipment (UE) (or "UE device") – Any of various types of computer systems or devices that are mobile or portable and perform wireless communication. Examples of UE devices include mobile phones or smartphones (e.g., iPhone TM , Android TM -based phones), tablets (e.g., iPad TM , Samsung Galaxy TM ), portable gaming devices (e.g., Nintendo DS TM , PlayStation Portable TM , Gameboy Advance TM , iPhone TM ), laptop computers, wearable devices (e.g., smartwatches, smart glasses), PDAs, portable Internet devices, music players, data storage devices, or other handheld devices, etc. Generally, the term "UE" or "UE device" can be broadly defined to include any electronic device, computing device, and / or telecommunications device (or combination of devices) that is convenient for a user to transport and capable of performing wireless communication.

[0053] Wireless device – Any of various types of computer systems or devices that perform wireless communication. A wireless device can be portable (or mobile), or can be fixed or stationary at a location. A UE is an example of a wireless device.

[0054] Communication device – Any of various types of computer systems or devices that perform communication, where the communication can be wired or wireless. A communication device can be portable (or mobile), or can be fixed or stationary at a location. A wireless device is an example of a communication device. A UE is another example of a communication device.

[0055] Base station – The term "base station" has the full scope of its ordinary meaning and includes at least a wireless communication station that is installed at a fixed location and used for communication as part of a wireless communication system.

[0056] Link budget limited - includes the full scope of its ordinary meaning and at least includes the characteristics of a wireless device (e.g., UE) that exhibits limited communication capabilities or limited power relative to a device that is not link budget limited or relative to a device for which a radio access technology (RAT) standard has been developed. A link budget limited wireless device may suffer from relatively limited receive and / or transmit capabilities, which may be due to one or more factors such as device design, device size, battery size, antenna size or design, transmit power, receive power, current transmission medium conditions, and / or other factors. Such a device may be referred to herein as a "link budget limited" (or "link budget constrained") device. A device may be inherently link budget limited due to its size, battery power, and / or transmit / receive power. For example, a smartwatch communicating with a base station via LTE or LTE-A may be inherently link budget limited due to its reduced transmit / receive power and / or reduced antenna. Wearable devices such as smartwatches are generally link budget limited devices. Alternatively, a device may not be inherently link budget limited, e.g., may have sufficient size, battery power, and / or transmit / receive power for normal communication via LTE or LTE-A, but may be temporarily link budget limited due to current communication conditions, e.g., a smartphone at the cell edge, etc. It should be noted that the term "link budget limited" includes or encompasses power limitations, and thus a link limited device may be considered a link budget limited device.

[0057] Processing element (or processor) - refers to various elements or combinations of elements capable of performing functions in a device (e.g., a user equipment device or a cellular network device). Processing elements may include, for example: a processor and associated memory, portions or circuits of individual processor cores, entire processor cores, separate processors, processor arrays, circuits such as ASICs (application specific integrated circuits), programmable hardware elements such as field programmable gate arrays (FPGAs), and any of the various combinations thereof.

[0058] Automatically - refers to an action or operation performed by a computer system (e.g., software executed by a computer system) or a device (e.g., circuitry, programmable hardware element, ASIC, etc.) without the need for user input directly specifying or performing the action or operation. Thus, the term "automatically" contrasts with a user manually performing or specifying an operation, where the user provides input to directly perform the operation. An automatic process can be initiated by input provided by the user, but the subsequent actions performed "automatically" are not specified by the user, i.e., they are not performed "manually", where the user specifies each action to be performed. For example, a user filling out a spreadsheet by selecting each field and providing input to specify information (e.g., by typing information, selecting checkboxes, radio component selections, etc.) is manually filling out the form, even though the computer system must update the form in response to the user's actions. The form can be filled out automatically by a computer system, where the computer system (e.g., software executing on a computer system) analyzes the fields of the form and fills out the form without any user input specifying the answers to the fields. As indicated above, the user can initiate the automatic filling of the form but does not participate in the actual filling of the form (e.g., the user does not manually specify the answers to the fields but they are automatically completed). This specification provides various examples of operations that are automatically performed in response to actions taken by the user.

[0059] Configured to - various components can be described as "configured to" perform one or more tasks. In such an environment, "configured to" is a broad statement generally meaning "having" the "structure" to perform one or more tasks during operation. Thus, even when the component is not currently performing a task, the component can be configured to perform the task (e.g., a set of electrical conductors can be configured to electrically connect a module to another module, even when the two modules are not connected). In some environments, "configured to" can be a broad statement generally meaning "having" the "circuitry" structure to perform one or more tasks during operation. Thus, even when the component is not currently powered on, the component can be configured to perform the task. Generally, the circuitry forming the structure corresponding to "configured to" can include hardware circuitry.

[0060] For ease of description, various components can be described as performing one or more tasks. Such a description should be interpreted to include the phrase "configured to". A component described as configured to perform one or more tasks is explicitly intended not to invoke the interpretation of 35 U.S.C. § 112, paragraph 6 for that component.

[0061] Figures 1 to 2 : a wireless communication system

[0062] Figure 1 illustrates an example of a wireless cellular communication system. It should be noted that Figure 1represents one of many possibilities and the features of the present disclosure can be implemented by any one of various systems as needed. For example, the embodiments described herein can be implemented in any type of wireless device.

[0063] As shown in the figure, an exemplary wireless communication system includes a cellular base station 102 that communicates with one or more wireless devices 106A, 106B, etc. and accessory devices 107 via a transmission medium. The wireless devices 106A, 106B, and 107 can be user equipment that may be referred to herein as “user devices” (UE) or UE devices.

[0064] The base station 102 can be a transceiver base station (BTS) or a cell site and can include hardware and / or software for implementing wireless communication with the UE devices 106A, 106B, and 107. If the base station 102 is implemented in the context of LTE, it can be referred to as an “eNodeB” or “eNB”. If the base station 102 is implemented in the context of 5G NR, it can alternatively be referred to as a “gNodeB” or “gNB”. The base station 102 can also be equipped to communicate with the network 100 (e.g., the core network of a cellular service provider, a telecommunications network such as the public switched telephone network (PSTN) and / or the Internet, and various possibilities). Thus, the base station 102 can facilitate communication between the UE devices 106 and 107 and / or communication between the UE devices 106 / 107 and the network 100. Also as used herein, in terms of the UE, the base station can sometimes be considered to represent the network when considering the uplink and downlink communications of the UE. Therefore, a UE that communicates with one or more base stations in the network can also be interpreted as a UE that communicates with the network.

[0065] In other specific embodiments, the base station 102 can be configured to provide communication via one or more other wireless technologies (such as an access point that supports one or more WLAN protocols), such as 802.11a, b, g, n, ac, ad, and / or ax, or LTE in the unlicensed band (LAA).

[0066] The communication area (or coverage area) of the base station 102 can be referred to as a “cell”. The base station 102 and the UE 106 / 107 can be configured to communicate via a transmission medium using any one of various radio access technologies (RAT) or wireless communication technologies (such as GSM, UMTS (WCDMA, TDS-CDMA), LTE, advanced LTE (LTE-A), NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-Fi, etc.).

[0067] Accordingly, the base station 102 and other similar base stations (not shown) operating according to one or more cellular communication technologies may be provided as a cell network that can provide continuous or nearly continuous overlapping services to the UE devices 106A-N and 107 and similar devices within a geographical area via one or more cellular communication technologies.

[0068] Note that, at least in some cases, the UE devices 106 / 107 may be capable of communicating using any one of a plurality of wireless communication technologies. For example, the UE devices 106 / 107 may be configured to communicate using one or more of GSM, UMTS, CDMA2000, LTE, LTE-A, NR, WLAN, Bluetooth, one or more Global Navigation Satellite Systems (GNSS, such as GPS or GLONASS), one and / or more mobile television broadcast standards (e.g., ATSC-M / H), etc. Other combinations of wireless communication technologies (including more than two wireless communication technologies) are also possible. Similarly, in some cases, the UE devices 106 / 107 may be configured to communicate using only a single wireless communication technology.

[0069] UE 106A and 106B may include handheld devices such as smart phones or tablets, and / or may include any of a variety of types of devices having cellular communication capabilities. For example, one or more of UE 106A and 106B may be wireless devices intended for static or dynamic deployment, such as home appliances, measurement devices, control devices, etc. UE 106B may be configured to communicate with a UE device 107 that may be referred to as an accessory device 107. The accessory device 107 may be any of a variety of types of wireless devices, which may generally be wearable devices having a smaller form factor and having limited battery, output power, and / or communication capabilities relative to the UE 106. As a common example, UE 106B may be a smart phone carried by a user, and the accessory device 107 may be a smart watch worn by the same user. UE 106B and the accessory device 107 may communicate using any of a variety of short-range communication protocols such as Bluetooth or Wi-Fi. In some cases, UE106B and the accessory device 107 may perform direct peer-to-peer communication using Proximity Services (ProSe) technology (e.g., in a manner supported by a cellular base station). For example, such ProSe communication may be performed as part of a relay link to support a radio resource control connection between the accessory device 107 and the BS 102, such as according to the various embodiments described herein.

[0070] UE 106B may also be configured to communicate with UE 106A. For example, UE 106A and UE 106B may be capable of performing direct device-to-device (D2D) communication. The D2D communication may be supported by the cellular base station 102 (e.g., BS 102 may facilitate discovery and various possible forms of assistance), or may be performed in a manner not supported by BS 102. For example, it may be possible for UE 106A and UE 106B to arrange and perform D2D communication (e.g., including discovery communication) even when there is no coverage from BS 102 and other cellular base stations.

[0071] Figure 2 An exemplary BS 102 communicating with the UE device 106 is shown, which in turn communicates with the accessory device 107. The UE device 106 and the accessory device 107 may be mobile phones, tablets, or any other type of handheld device, smart watch or other wearable device, media player, computer, laptop, or almost any type of wireless device. In some embodiments, the accessory device may be a wireless device designed to have low cost and / or low power consumption, and may benefit from a relay link with the UE device 106 (and / or another companion device) to support communication with the BS 102. For example, in Figure 2 an illustrative scenario, a device that uses a relay link with another wireless device to communicate with a cellular base station may also be referred to herein as a remote wireless device, remote device, or remote UE device, while a wireless device that provides such a relay link may also be referred to herein as a relay wireless device, relay device, or relay UE device. According to some embodiments, such BS 102, UE 106, and accessory device 107 may be configured to perform radio resource control procedures on the remote wireless device according to the various techniques described herein.

[0072] Both the UE 106 and the accessory device 107 may include a device or integrated circuit known as a cellular modem for facilitating cellular communication. The cellular modem may include one or more processors (processing elements) configured to execute program instructions stored in a memory and / or various hardware components described herein. The UE 106 and / or the accessory device 107 may each execute any of the method embodiments described herein by executing such stored instructions. Alternatively or in addition, the UE 106 and / or the accessory device 107 may also include programmable hardware elements such as FPGAs (field programmable gate arrays), integrated circuits, and / or any of various other possible hardware components configured to execute (e.g., individually or in combination) any one or any part of any of the method embodiments described herein. The cellular modem described herein may be used in a UE device as defined herein, a wireless device as defined herein, or a communication device as defined herein. The cellular modem described herein may also be used in a base station or other similar network-side device.

[0073] The UE 106 and / or the accessory device 107 may include one or more antennas for communicating according to one or more RAT standards using one or more wireless communication protocols. In some embodiments, one or both of the UE 106 or the accessory device 107 may be configured to communicate using a single shared radio component. The shared radio component may be coupled to a single antenna or may be coupled to multiple antennas (e.g., for MIMO) for performing wireless communication. Generally, the radio component 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 and other digital processing). Similarly, the radio component may implement one or more receive chains and transmit chains using the foregoing hardware.

[0074] Alternatively, UE 106 and / or accessory device 107 may include two or more radio components. For example, in some embodiments, for each wireless communication protocol configured to communicate therewith, UE 106 or accessory device 107 may include separate transmit and / or receive chains (e.g., including separate antennas and other radio components). As another possibility, UE 106 and / or accessory device 107 may include one or more radio components shared among multiple wireless communication protocols, and one or more radio components uniquely used by a single wireless communication protocol. For example, UE 106 and / or accessory device 107 may include shared radio components for communicating using any of LTE or CDMA2000 1xRTT (or LTE or NR, or LTE or GSM), and separate radio components for communicating using each of Wi-Fi and BLUETOOTH TM for communicating. Other configurations are possible.

[0075] Figure 3 : Block diagram of a UE device

[0076] Figure 3 A possible block diagram of a UE device such as UE device 106 or 107 is shown. As shown, UE device 106 / 107 may include a system-on-chip (SOC) 300, which may include portions for various purposes. For example, as shown, SOC 300 may include: a processor 302, which may execute program instructions for UE device 106 / 107; and display circuitry 304, which may perform graphics processing and provide a display signal to a display 360. SOC 300 may also include motion sensing circuitry 370, which may detect the motion of UE 106 using, for example, a gyroscope, an accelerometer, and / or any of various other motion sensing components. Processor 302 may also be coupled to a memory management unit (MMU) 340, which may be configured to receive addresses from processor 302 and translate those addresses into locations in a memory (e.g., memory 306, read-only memory (ROM) 350, flash memory 310) and / or other circuits or devices, such as display circuitry 304, radio components 330, I / F 320, and / or display 360. MMU 340 may be configured to perform memory protection and page table translation or setup. In some embodiments, MMU 340 may be included as part of processor 302.

[0077] As shown, the SOC 300 can be coupled to various other circuits of the UE 106 / 107. For example, the UE 106 / 107 can include various types of memories (e.g., including NAND flash memory 310), a connector interface 320 (e.g., for coupling to a computer system, docking station, charging station, etc.), a display 360, and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR, CDMA2000, Bluetooth, Wi-Fi, NFC, GPS, etc.).

[0078] The UE device 106 / 107 can include at least one antenna and in some embodiments can include multiple antennas 335a and 335b for performing wireless communication with a base station and / or other devices. For example, the UE device 106 / 107 can use antennas 335a and 335b to perform wireless communication. As described above, the UE device 106 / 107 can be configured to use multiple wireless communication standards or radio access technologies (RATs) for wireless communication in some embodiments.

[0079] The wireless communication circuitry 330 can include Wi-Fi logic 332, a cellular modem 334, and Bluetooth logic 336. The Wi-Fi logic 332 is for enabling the UE device 106 / 107 to perform Wi-Fi communication on an 802.11 network. The Bluetooth logic 336 is for enabling the UE device 106 / 107 to perform Bluetooth communication. The cellular modem 334 can be a lower power cellular modem capable of performing cellular communication according to one or more cellular communication technologies.

[0080] As described herein, the UE 106 / 107 can include hardware components and software components for implementing embodiments of the present disclosure. The processor 302 of the UE device 106 / 107 can be configured to implement part or all of the methods described herein, such as by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, the processor 302 can be configured as a programmable hardware element, such as an FPGA (field programmable gate array) or as an ASIC (application specific integrated circuit). Additionally, the processor 302 can be coupled to as Figure 3The other components shown and / or can interoperate with it to perform radio resource control procedures for remote wireless devices according to various embodiments disclosed herein. The processor 302 can also implement various other applications and / or end-user applications running on the UE 106. Alternatively or in addition, one or more components of the wireless communication circuitry 330 (e.g., cellular modem 334) of the UE device 106 / 107 can be configured to implement part or all of the methods described herein, for example, by a processor that executes program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), a processor configured as an FPGA (field programmable gate array), and / or a processor using dedicated hardware components that may include an ASIC (application specific integrated circuit).

[0081] Figure 4 : Block diagram of a base station

[0082] Figure 4 An exemplary block diagram of a base station 102 according to some embodiments is shown. Note that Figure 4 the base station shown is only one example of a possible base station. As shown, the base station 102 can include a processor 404 that can execute program instructions for the base station 102. The processor 404 can also be coupled to a memory management unit (MMU) 440 (which can be configured to receive addresses from the processor 404 and translate these addresses into locations in a memory (e.g., memory 460 and read-only memory (ROM) 450)) or coupled to other circuits or devices.

[0083] The base station 102 can include at least one network port 470. As described above in Figure 1 and Figure 2 the network port 470 can be configured to be coupled to a telephone network and provide access to the telephone network for a plurality of devices, such as UE devices 106 / 107.

[0084] The network port 470 (or an additional network port) can be further configured or alternatively configured to be coupled to a cellular network, such as the core network of a cellular service provider. The core network can provide mobility-related services and / or other services to a plurality of devices, such as UE devices 106 / 107. For example, the core network can include, for example, a mobility management entity (MME) for providing mobility management services, a serving gateway (SGW) for providing, for example, an external data connection to the Internet, and / or a packet data network gateway (PGW), and so on. In some cases, the network port 470 can be coupled to the telephone network via the core network, and / or the core network can provide the telephone network (e.g., between other UE devices served by a cellular service provider).

[0085] Base station 102 may include at least one antenna 434 and possibly multiple antennas. One or more antennas 434 may be configured to operate as a wireless transceiver and may be further configured to communicate with UE devices 106 / 107 via radio component 430. One or more antennas 434 communicate with radio component 430 via communication link 432. Communication link 432 may be a receive link, a transmit link, or both. Radio component 430 may be configured to communicate via various wireless communication standards, including but not limited to LTE, LTE-A, NR, GSM, UMTS, CDMA2000, Wi-Fi, etc.

[0086] Base station 102 may be configured to perform wireless communication using multiple wireless communication standards. In some cases, base station 102 may include multiple radio components that enable base station 102 to communicate according to multiple wireless communication technologies. For example, as a possibility, base station 102 may include an LTE radio component for performing communication according to LTE and a Wi-Fi radio component for performing communication according to Wi-Fi. In such cases, base station 102 may be able to operate as both an LTE base station and a Wi-Fi access point. As another possibility, base station 102 may include a multi-mode radio component capable of performing communication according to any one of multiple wireless communication technologies (e.g., LTE and NR, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

[0087] As further described subsequently herein, BS 102 may include hardware and software components for implementing or supporting the implementation of the features described herein. According to some embodiments, processor 404 of base station 102 may be configured to implement part or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, 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), in combination with one or more of the other components 430, 432, 434, 440, 450, 460, 470, processor 404 of BS 102 may be configured to implement or support the implementation of radio resource control procedures of a remote wireless device and / or various other features described herein according to the various embodiments disclosed herein.

[0088] Figure 5 : Communication Flowchart

[0089] Figure 5is a communication flow diagram showing a method for performing radio resource control procedures for a remote radio device in a wireless communication system. In various embodiments, some of the method elements shown may be performed simultaneously in a different order than shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be performed as needed.

[0090] Figure 5 Aspects of the method may be implemented by a wireless device and / or a cellular base station, such as the Figures 1 to 4 shown and described with respect to Figures 1 to 4 UEs 106A - B and / or BS 102, or more generally, may be implemented in any other device as needed in combination with any of the computer systems or devices shown in the above figures. Note that although aspects of the Figure 5 method are described in a manner that involves using communication technologies and / or features associated with LTE, NR, and / or 3GPP specification documents, this description is not intended to limit the present disclosure, and aspects of the Figure 5 method may be used in any suitable wireless communication system as needed. As shown, the method may operate as follows.

[0091] At 502, a wireless device (“first wireless device” or “remote wireless device”) 107 may perform a radio resource control (RRC) procedure with a cellular base station 102 via another wireless device (“second wireless device” or “relay wireless device”) 106. The remote wireless device may be any of various types of wireless devices capable of indirectly performing wireless communication with a cellular base station via an intermediate relay wireless device. As one possibility, the remote wireless device may be an accessory device, such as a smartwatch or other wearable device configured as a low - cost and / or low - power wireless device. The relay wireless device may be any of various types of wireless devices capable of supporting wireless communication between the remote wireless device and the cellular base station by acting as an intermediate relay wireless device. As one possibility, the relay wireless device may be a smart phone capable of acting as a companion device for the remote wireless device. Many other types of wireless devices may also serve as the remote wireless device and / or the relay wireless device. The cellular base station may be any of various types of base stations capable of indirectly performing wireless communication with the remote wireless device via an intermediate relay wireless device and capable of providing access to a cellular network. As one possibility, the cellular base station may be a 3GPP 5G NR gNB. Alternatively (or in addition), the cellular base station may be capable of operating according to any of various other possible cellular communication standards.

[0092] The RRC procedure can include any one of various RRC procedures. At least according to some embodiments, the RRC procedure can be used to attempt to establish an RRC connection between a remote wireless device and a cellular base station. For example, the remote wireless device can attempt to perform an RRC connection procedure, an RRC reestablishment procedure, or an RRC resume procedure. As another possibility, the RRC procedure can be used to reconfigure an existing RRC connection between the remote wireless device and the cellular base station (e.g., the cellular base station can attempt to perform an RRC reconfiguration procedure), or can be used to release an existing RRC connection between the remote wireless device and the cellular base station (e.g., the cellular base station can attempt to perform an RRC release procedure).

[0093] To perform the RRC procedure, the relay wireless device can relay RRC messages between the remote wireless device and the cellular base station. For example, to perform an RRC connection procedure, the remote wireless device can transmit an RRC connection request to the relay wireless device, which in turn can transmit the RRC connection request to the cellular base station on behalf of the remote wireless device. The cellular base station can transmit an RRC setup message configured to facilitate the establishment of the RRC connection with the remote wireless device to the relay wireless device in response to the RRC connection request. The relay wireless device can then transmit the RRC setup message to the remote wireless device on behalf of the cellular base station, for example, including configuration information for establishing the RRC connection. The remote wireless device can also transmit an RRC setup complete message to the relay wireless device, which in turn can transmit the RRC setup complete message to the cellular base station on behalf of the remote wireless device.

[0094] Note that the RRC messages relayed by the relay wireless device between the remote wireless device and the cellular base station can be different for different RRC procedures. According to some embodiments, some or all of the RRC messages can be relayed intact by the relay wireless device. As another possibility, some or all of the content of the RRC messages can not be relayed, and / or additional information can be added to some or all of the relayed RRC messages. For example, in some cases, the configuration information for establishing a remote RRC connection can include some information used by the relay wireless device to establish one or more relay signaling radio bearers between the relay wireless device and the cellular base station, which the remote wireless device may not need to establish the remote RRC connection.

[0095] As another possibility, when relaying an RRC message on behalf of a remote wireless device to a cellular base station, the relay wireless device may provide the cellular base station with identification information associated with the remote wireless device, e.g., for indicating to the cellular base station that the RRC message is being provided on behalf of the remote wireless device, and similarly, when relaying an RRC message on behalf of a remote wireless device to the relay wireless device, the cellular base station may provide the relay wireless device with identification information associated with the remote wireless device, e.g., for indicating to the relay wireless device that an RRC message is being provided on behalf of the remote wireless device. In some cases, providing such identification information may be used to distinguish RRC messages related to the RRC connection between the relay wireless device and the cellular base station and RRC messages related to the RRC connection between the remote wireless device and the cellular base station. Such a distinction is also possible by using a different signaling radio bearer for the relayed RRC message than for RRC messages related to the RRC connection between the relay wireless device and the cellular base station. If the relay wireless device is configured to relay RRC messages between the cellular base station and each of a plurality of remote wireless devices, providing such identification information may also be used to identify which RRC messages are related to which RRC connections; e.g., in such a case, it may be that each RRC message relayed between the cellular base station and a corresponding remote wireless device includes remote wireless device identification information for the corresponding remote wireless device.

[0096] At least according to some embodiments, the relay wireless device may transmit a discovery broadcast message (e.g., event-driven or periodically triggered) indicating that the relay wireless device supports relaying RRC messages. The remote wireless device may receive the discovery broadcast message from the relay wireless device (and possibly from one or more other wireless devices capable of supporting relaying RRC messages). The remote wireless device may perform link selection to determine a wireless link on which to attempt to establish a relayed RRC connection with the cellular base station and may select the relay wireless device based at least in part on the discovery broadcast message received from the relay wireless device. The remote wireless device may attempt to perform an RRC procedure with the cellular base station via the relay wireless device based at least in part on the link selection.

[0097] Since a remote RRC connection can rely on multiple wireless links (e.g., a wireless link between a remote wireless device and a relay wireless device, and a wireless link between the relay wireless device and a cellular base station), it may be beneficial to provide techniques for handling wireless link interruptions. According to some embodiments, one or both of the remote wireless device or the relay wireless device may utilize a response timer to help determine whether a link failure has occurred in the wireless link between the remote wireless device and the relay wireless device. For example, the relay wireless device may start a response validity timer at least in part based on relaying a radio resource control message to the remote wireless device, and may stop the response validity timer when a response is received from the remote wireless device. If the response validity timer expires without receiving a response, the relay wireless device may determine that a link failure has occurred in the wireless link between the relay wireless device and the remote wireless device. If the relay wireless device determines that a link failure has occurred in the wireless link between the relay wireless device and the remote wireless device, e.g., in this manner or in any of various other ways, the relay wireless device may provide an indication of the link failure of the wireless link between the relay wireless device and the remote wireless device to the cellular base station. At least in some cases, the relay wireless device may receive an indication from the cellular base station to release the remote wireless device in response to the indication of the link failure of the wireless link between the relay wireless device and the remote wireless device.

[0098] In some embodiments, the remote wireless device may start a response guard timer at least in part based on providing a radio resource control message to the relay wireless device, and may stop the response guard timer when a response to the radio resource control message is received from the relay wireless device. If the response guard timer expires without receiving a response, the remote wireless device may determine that a link failure has occurred in the wireless link between the remote wireless device and the relay wireless device. In this case, the remote wireless device may perform link selection to determine a wireless link on which to attempt to establish a relayed radio resource control connection with the cellular base station, e.g., at least in part based on the link failure of the wireless link between the remote wireless device and the relay wireless device.

[0099] According to some embodiments, an acknowledgement may generally be provided in response to an RRC message transmitted as part of a remote RRC procedure (e.g., the relay signaling radio bearer used may be configured as an acknowledged mode or AM). Based on such acknowledgement (or lack thereof) and / or in any of a variety of other ways, the relay radio device is also able to determine whether a link failure has occurred in the radio link between the relay radio device and the cellular base station. If such a link failure is detected, the relay radio device may provide an indication of the link failure of the radio link between the relay radio device and the cellular base station to the remote radio device. The indication may include any of the following explicit indications: a link failure has occurred in the radio link between the relay radio device and the cellular base station, an indication to suspend the radio link between the relay radio device and the remote radio device, or an indication to release the radio link between the relay radio device and the remote radio device. Based on the indication (e.g., if an indication to release the radio link between the first radio device and the second radio device is received), the remote radio device may perform link selection to re-determine the radio link on which to attempt to establish a radio resource control connection to the cellular base station via the relay. Alternatively (e.g., if an indication to suspend the radio link between the relay radio device and the remote radio device is received), the remote radio device may wait for up to a specific period of time before performing link selection, e.g., in the case where the relay radio device is able to re-establish a radio link with the cellular network and resume relaying RRC messages on behalf of the remote radio device.

[0100] Thus, using the techniques described herein, a remote radio device may establish and manage an RRC connection with a cellular network via a relay radio device, and the remote radio device, the relay radio device, and the cellular network may handle potential link failures of the radio link for supporting the remote RRC connection. At least according to some embodiments, such techniques may be used to support cellular communication of a wider type of radio devices, e.g., potentially helping to extend the range of possible radio devices that can further utilize cellular communication for low-cost and / or low-power radio devices.

[0101] Figures 6 to 23 and additional information

[0102] is provided Figures 6 to 23 and additional information below, which illustrates further considerations and possible specific implementation details related to Figure 5 the method and is not intended to limit the present disclosure generally. Various variations and alternatives of the details provided below are possible and should be considered to fall within the scope of the present disclosure.

[0103] The 3GPP 5G NR cellular communication technology is being developed for a variety of uses, including enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC). mMTC use cases can include the widespread deployment of wireless devices designed to have relatively low cost and / or low power consumption. Such devices can include any of wearable devices, appliances, process control devices, measurement devices, and / or a variety of other types of devices. In at least some embodiments (e.g., in some cases, wearable devices), it may be the case that such devices are generally relatively close to another wireless device (e.g., in some cases, a smart phone) that can be used as a relay for communication with the cellular network. Thus, at least in some embodiments, it is advantageous to support a UE-to-NW communication relay framework, e.g., to help support the operation of low-cost and / or low-power wireless devices that can benefit from such a framework. For example, Figure 6 Aspects of one possible exemplary wireless communication relay between a remote UE 602, a relay UE 604, and a cellular base station 606 are shown. As shown, in the illustrated scenario, the remote UE 602 can communicate with the cellular base station 606 via a relay link between the remote UE 606 and the relay UE 602 and a Uu link between the relay UE 604 and the cellular base station 604.

[0104] According to various embodiments, there can be multiple possible types of UE-to-NW relay frameworks. As one possibility, at least in some cases, a 3-layer relay that can be implemented without affecting the access layer communication layer can be used. As another possibility, a 2-layer relay can be used, e.g., by establishing and maintaining a radio resource control connection that terminates between the remote UE and the cellular base station. Figures 7 to 8 Exemplary aspects of a possible protocol stack architecture for user plane and control plane communication in a 3GPP-based UE-to-network relay framework are shown, where the communication relay is implemented at layer 2.

[0105] More specifically, Figure 7 A user plane radio protocol stack for a 2-layer UE-to-network relay is shown that utilizes a PC5 interface between a remote UE 702 and a relay UE 704 to provide a communication link between the remote UE 702 and an eNB 706 and to provide a communication link to a core network 708 accessed by the eNB 706. Similarly, Figure 8Shows a control plane radio protocol stack for two-layer UE-to-network relay, which uses the PC5 interface between the remote UE 802 and the relay UE 804 to provide a communication link between the remote UE 802 and the eNB 806, and provides a communication link to the core network 808 accessible to the eNB 806. As shown, the relay can be performed above the RLC sublayer. The Uu PDCP and RRC links can be terminated between the remote UE and the eNB, while the RLC, MAC, and PHY, as well as the non-3GPP transport layer, are terminated in each link (e.g., the link between the remote UE and the relay UE, and the link between the relay UE and the eNB).

[0106] Currently, the RRC connection procedure can be performed between the UE and the network via a direct connection on the Uu interface, e.g., according to 3GPP-based cellular communication. For the RRC connection procedure between remote UEs, where peer RRC entities are terminated at the remote UE and at the network, the RRC message transmission can be relayed via the relay UE, e.g., such that in addition to the Uu link between the relay UE and the network, there can also be an additional relay link between the relay UE and the remote UE. Since the Uu link and the relay link can be maintained independently, the remote RRC procedure may fail due to the interruption of the relay link or the Uu link. Therefore, it may be important to carefully design the RRC procedure framework to support the ability of the remote UE to perform the RRC procedure.

[0107] According to some embodiments, the RRC message delivery of the remote UE via the Uu link can be performed via a relay signaling radio bearer (SRB) established between the network and the relay UE. The network may be capable of establishing one or more relay SRBs. It is possible that all relay SRBs are configured in the radio link control (RLC) acknowledged mode (AM). In the case of using multiple relay SRBs, different relay SRBs can be used for different types of signaling. For example, as a possibility, relay SRB0 can be used for 3GPP SRB0 transmission, relay SRB1 can be used for 3GPP SRB1 transmission, and relay SRB2 can be used for 3GPP SRB2 transmission. Note that other configurations are also possible. The relay SRB may be common to all remote UEs that have established a relay link with a given relay UE. It is possible that each RRC message of the remote UE is transmitted together with the remote UE identifier, e.g., in order to distinguish the RRC messages of different remote UEs within one relay SRB.

[0108] As previously described herein, link failure detection can be an important consideration for supporting remote RRC procedures. For two-way RRC procedures (e.g., expecting a response to each message of the RRC procedure), the relay UE may be able to utilize a response validity timer to control RRC response messages from the remote UE via the relay link. For example, the relay UE may start the response validity timer when sending an RRC message to the remote UE and stop the timer when the relay UE receives the expected RRC response from the remote UE. When the timer expires (e.g., if an RRC response is received from the remote UE while the timer is running), the relay UE may determine that the RRC message transmitted via the relay link has failed.

[0109] For each possible RRC procedure, if the relay UE can detect that an RRC message transmission failure has occurred (e.g., in the relay link or the Uu link), the relay UE may take actions in response to the RRC message transmission failure. For example, for a relay link failure scenario, the relay UE may notify the network of the relay link failure. For a Uu link failure scenario, the relay UE may provide information to the remote UE based on the Uu link failure, which may facilitate the remote UE to perform link reselection. For example, as one possibility, the relay UE may send an indication of the Uu link failure to the remote UE. As another possibility, the relay UE may send an indication to suspend the relay link to all remote UEs having a relay link established with the relay UE. As another possibility, the relay UE may directly close the relay link with the remote UE (e.g., may not explicitly indicate that a Uu link failure has occurred).

[0110] Figures 9 to 14 is a signal flow diagram showing further details of various possible remote RRC procedures. Figure 9 Shows aspects of an exemplary scenario according to some embodiments, in which multiple remote UEs attempt to establish an RRC connection with a gNB via the same relay UE. In the exemplary scenario, the RRC message delivery of the remote UE in the Uu link may be performed on a relay SRB established between the relay UE and the network.

[0111] As shown in the figure, in the illustrated scenario, at 910, the relay UE 906 may establish an RRC connection with the gNB 908, potentially including establishing a relay SRB configuration. This may include establishing a relay SRB1 for remote UE SRB0 transmission and a relay SRB2 for remote UE SRB1 and SRB2 transmissions. At 912, the first remote UE 902 may provide an RRC connection request to the relay UE 906. At 914, the relay UE 906 may provide a connection request to the gNB 908 on behalf of the first remote UE 902, for example, including identification information for the first remote UE 902. The connection request may be provided using the relay SRB1, for example, because it can relay SRB0 transmissions from the first remote UE 902. At 916, the second remote UE 904 may provide an RRC connection request to the relay UE 906. At 918, the relay UE 906 may provide a connection request to the gNB 908 on behalf of the second remote UE 904, for example, including identification information for the second remote UE 904. The connection request may be provided using the relay SRB1, for example, because it can relay SRB0 transmissions from the first remote UE 902.

[0112] At 920, the gNB 908 may provide an RRC setup message intended for the first remote UE 902 to the relay UE 906. The RRC setup message intended for the first remote UE 902 may include identification information for the first remote UE 902. At 922, the relay UE 906 may provide the RRC setup message to the first remote UE 902 on behalf of the gNB 908. Similarly, at 924, the gNB 908 may provide an RRC setup message intended for the second remote UE 904 to the relay UE 906. The RRC setup message intended for the second remote UE 904 may include identification information for the second remote UE 904. At 926, the relay UE 906 may provide the RRC setup message to the second remote UE 904 on behalf of the gNB 908. Note that for the two RRC setup messages provided by the gNB 908, the relay SRB1 may be used again.

[0113] In 928, the first remote UE 902 may provide an RRC establishment complete message to the relay UE 906. In 930, the relay UE 906 may provide an RRC setup complete message to the gNB 908 on behalf of the first remote UE 902, for example including identification information for the first remote UE 902. The RRC setup complete message may be provided using the relay SRB2, for example, because it may relay SRB1 transmissions from the first remote UE 902. In 932, the second remote UE 904 may provide an RRC establishment complete message to the relay UE 906. In 934, the relay UE 906 may provide an RRC setup complete message to the gNB 908 on behalf of the second remote UE 904, for example including identification information for the second remote UE 904. The RRC setup complete message may be provided using the relay SRB2, for example, because it may relay SRB1 transmissions from the second remote UE 904. Note that different types of remote UE identification information may be used for different SRBs. For example, for SRB0 transmissions, the remote UE identification information may be assigned by the relay UE, while for SRB1 transmissions, the remote UE identification may include full or partial cell radio network temporary identifier (C-RNTI) information.

[0114] Figure 10Aspects of an exemplary scenario according to some embodiments are shown, in which a single remote UE attempts to establish an RRC connection with a gNB via a relay UE. As shown, in the illustrated scenario, at 1008, the remote UE 1002 may provide an RRC connection request to the relay UE 1004. At 1010, the remote UE 1002 and the relay UE 1004 may be connected. At 1012, the relay UE 1004 may use the relay SRB to provide an RRC connection request to the gNB 1006 and indicate the identification information of the remote UE 1002. At 1014, the gNB 1006 may use the relay SRB to provide an RRC connection establishment message to the relay UE 1004. The RRC connection setup message may include the C-RNTI information of the remote UE 1002, as well as any one of relay link configuration information, bearer configuration information, Uu data radio bearer configuration information, mapping configuration information, and / or various information that supports the establishment of a remote RRC connection between the gNB 1006 and the remote UE 1002. At 1016, the relay UE 1004 may provide an RRC connection setup message to the remote UE 1002, including at least some of the information received from the gNB 1006, such as any information (e.g., relay link configuration information, bearer configuration information) that the remote UE 1002 needs as part of establishing a remote RRC connection between the gNB 1006 and the remote UE 1002. At 1018, the remote UE 1002 may connect to the gNB 1006. At 1020, the remote UE 1002 may complete the establishment of the RRC connection with the gNB 1006 by providing an RRC setup complete message to the relay UE 1004, and at 1022, the relay UE 1004 may use the relay SRB to provide an RRC setup complete message to the gNB 1006 and indicate the identification information of the remote UE 1002. At 1024, the gNB 1006 may also connect to the remote UE 1002.

[0115] Figure 11Aspects of an exemplary scenario according to some embodiments are shown, where a single remote UE attempts to re - establish an RRC connection with a gNB via a relay UE. As shown, in the illustrated scenario, at 1108, the remote UE 1102 and the relay UE 1104 can be connected. At 1110, the remote UE 1102 can provide an RRC re - establishment request to the relay UE 1104. At 1112, the relay UE 1104 can use a relay SRB to provide an RRC re - establishment request to the gNB 1106 and indicate the identification information of the remote UE 1102. At 1114, the gNB 1106 can use the relay SRB to provide an RRC re - establishment message to the relay UE 1104. The RRC re - establishment message can include the C - RNTI information of the remote UE 1102, as well as any one of relay link configuration information, bearer configuration information, Uu data radio bearer configuration information, mapping configuration information, and / or various information supporting the re - establishment of the remote RRC connection between the gNB 1106 and the remote UE 1102. At 1116, the relay UE 1004 can provide an RRC re - establishment message to the remote UE 1102, including at least some of the information received from the gNB 1106, such as any information (e.g., relay link configuration information, bearer configuration information) that the remote UE 1102 needs as part of re - establishing the remote RRC connection between the gNB 1106 and the remote UE 1102. At 1118, the remote UE 1102 can connect to the gNB 1106. At 1120, the remote UE 1102 can complete the re - establishment of the RRC connection with the gNB 1106 by providing an RRC re - establishment complete message to the relay UE 1104, and at 1122, the relay UE 1104 can use the relay SRB to provide an RRC re - establishment complete message to the gNB 1106 and indicate the identification information of the remote UE 1102. At 1124, the gNB 1106 can also connect to the remote UE 1102.

[0116] Figure 12Aspects of an exemplary scenario according to some embodiments are shown, where a single remote UE attempts to resume an RRC connection with a gNB via a relay UE. As shown, in the illustrated scenario, at 1208, the remote UE 1202 may provide an RRC resume request to the relay UE 1204. At 1210, the remote UE 1202 and the relay UE 1204 may be connected. At 1212, the relay UE 1204 may use a relay SRB to provide an RRC resume request to the gNB 1206 and indicate the identification information of the remote UE 1202. At 1214, the gNB 1206 may use the relay SRB to provide an RRC resume message to the relay UE 1204. The RRC resume message may include the C-RNTI information of the remote UE 1202, as well as any one of relay link configuration information, bearer configuration information, Uu data radio bearer configuration information, mapping configuration information, and / or various information supporting the resume of the remote RRC connection between the gNB 1206 and the remote UE 1202. At 1216, the relay UE 1204 may provide the RRC resume message to the remote UE 1202, including at least some of the information received from the gNB 1206, such as any information (e.g., relay link configuration information, bearer configuration information) that the remote UE 1202 needs as part of resuming the remote RRC connection between the gNB 1206 and the remote UE 1202. At 1218, the remote UE 1202 may connect to the gNB 1206. At 1220, the remote UE 1202 may complete the RRC resume process with the gNB 1206 by providing an RRC resume completion message to the relay UE 1204, and at 1222, the relay UE 1204 may use the relay SRB to provide the RRC resume completion message to the gNB 1206 and indicate the identification information of the remote UE 1202. At 1224, the gNB 1206 may also connect to the remote UE 1202.

[0117] Figure 13Aspects of an exemplary scenario in accordance with some embodiments are shown, in which a gNB releases a remote RRC connection with a remote UE via a relay UE; as shown, in the illustrated scenario, at 1308, the remote UE 1302 and the relay UE 1304 may each be connected to each other and have an RRC connection with the gNB 1306. At 1310, the gNB 1306 may provide an RRC release message to the relay UE 1304 using a relay SRB. The RRC release message may include identification information of the remote UE 1302, as well as relay link configuration information, bearer configuration information, Uu data radio bearer configuration information, mapping configuration information, and / or any one of various information that supports the release of the remote RRC connection between the gNB 1306 and the remote UE 1302. At 1312, the relay UE 1304 may provide the RRC release message to the remote UE 1302, including at least some of the information received from the gNB 1306, such as any information (e.g., relay link configuration information, bearer configuration information) that the remote UE 1302 needs as part of the release of the remote RRC connection between the gNB 1306 and the remote UE 1302. At 1314, the remote UE 1302 may enter the idle mode due to the release of the remote RRC connection. Note that, as an alternative, at least according to some embodiments, the remote UE 1302 may be released to the inactive mode.

[0118] Figure 14Aspects of an exemplary scenario according to some embodiments are shown, where a gNB reconfigures a remote RRC connection with a remote UE via a relay UE; as shown, in the illustrated scenario, in 1408, the remote UE 1402 and the relay UE 1404 may each be connected to each other and have an RRC connection with the gNB 1406. In 1410, the gNB 1406 may provide an RRC reconfiguration message to the relay UE 1404 using a relay SRB. The RRC reconfiguration message may include identification information of the remote UE 1402, as well as any one of relay link configuration information, bearer configuration information, Uu data radio bearer configuration information, mapping configuration information, and / or various information supporting the reconfiguration of the remote RRC connection between the gNB 1406 and the remote UE 1402. In 1412, the relay UE 1404 may provide the RRC reconfiguration message to the remote UE 1402, including at least some of the information received from the gNB 1406, such as any information (e.g., relay link configuration information, bearer configuration information) that the remote UE 1402 needs as part of reconfiguring the remote RRC connection between the gNB 1406 and the remote UE 1402. In 1414, the remote UE 1402 may provide an RRC reconfiguration complete message to the relay UE 1404, and in 1416, the relay UE 1404 may use the relay SRB to provide the RRC reconfiguration complete message to the gNB 1406 and indicate the identification information of the remote UE 1402.

[0119] In addition to providing a framework for relaying RRC messages between a remote UE and a gNB, a framework for detecting and handling link failures together with a remote RRC connection may also be provided. As an aspect of such a framework, it may be that the relay SRB is configured to have a radio link control (RLC) acknowledged mode (AM). Thus, if the transmission of an RRC message of a remote UE fails due to a link failure between the relay UE and the network, the relay UE may detect the RLC failure and trigger a radio link failure (RLF). In the Uu link, the relay UE may perform an RRC connection reestablishment procedure or a secondary cell group (SCG) failure recovery procedure. With respect to the relay link, the relay UE may send a Uu link failure indication to the remote UE, or may send a suspend relay link indication to the remote UE (and possibly any other remote UE connected to the relay UE), or may directly close the relay link.

[0120] The remote UE may perform link reselection based on Uu link failure. For example, if the ongoing procedure is for establishment / re - establishment / resumption, the remote UE may retry the procedure on the newly selected link. If the ongoing exchange is for another procedure such as re - configuration, if the access stratum (AS) security has been activated, the remote UE may perform a re - establishment procedure on the newly selected link. Otherwise, if the AS security is not activated, the UE may perform an RRC connection establishment procedure on the newly selected link. Note that if an RRC message transmission failure of the remote UE occurs while the network is transmitting to the relay UE, the network may be able to re - configure the relay SRB and re - transmit the message.

[0121] Figures 15 to 17 is a signaling flow diagram showing aspects of various possible scenarios where the RRC procedure between the remote UE and the gNB fails due to a link failure between the relay UE and the gNB.

[0122] Specifically, Figure 15Shows some aspects of an exemplary scenario according to some embodiments, where remote RRC connection establishment fails due to a link failure between the relay UE and the gNB. As shown, in the illustrated scenario, in 1508, the remote UE 1502 may provide an RRC connection request to the relay UE 1504. In 1510, the remote UE 1502 and the relay UE 1504 may be connected. In 1512, the relay UE 1504 may use the relay SRB to provide an RRC connection request to the gNB 1506 and indicate the identification information of the remote UE 1502. In 1514, the gNB 1506 may use the relay SRB to provide an RRC connection establishment message to the relay UE 1504. In 1516, the relay UE 1504 may provide an RRC connection setup message to the remote UE 1502. In 1518, the remote UE 1502 may connect to the gNB 1506. In 1520, the remote UE 1502 may attempt to complete the RRC connection establishment with the gNB 1506 by providing an RRC setup completion message to the relay UE 1504, and in 1522, the relay UE 1504 may use the relay SRB to provide an RRC setup completion message to the gNB 1506 and indicate the identification information of the remote UE 1502. However, the delivery of the RRC setup completion message may fail, and in 1524, the relay UE 1504 may declare a Uu link RLF. In 1526, the relay UE 1504 may stop providing discovery broadcasts, and in 1528, may provide an indication to the remote UE 1502 to suspend the relay link between the remote UE 1502 and the relay UE 1504. In 1530, the remote UE 1502 may enter the idle mode. In 1532, the relay UE 1504 and the gNB 1506 may perform an RRC connection reestablishment procedure. In 1534, the remote UE 1502 may perform link reselection. In 1536, the relay UE 1504 may resume providing discovery broadcasts. In 1538, the remote UE 1502 may transmit a new RRC connection request to the relay UE 1504 or possibly to another wireless device, for example, according to the result of link selection.

[0123] Figure 16Shows some aspects of an exemplary scenario according to some embodiments, where the re - establishment of a remote RRC connection fails due to a link failure between the relay UE and the gNB. As shown, in the illustrated scenario, at 1608, the remote UE 1602 may provide an RRC re - establishment request to the relay UE 1604. At 1610, the remote UE 1602 and the relay UE 1604 may be connected. At 1612, the relay UE 1604 may use the relay SRB to provide an RRC re - establishment request to the gNB 1606 and indicate the identification information of the remote UE 1602. However, the delivery of the RRC re - establishment request may fail, and at 1614, the relay UE 1604 may declare a Uu link RLF. At 1616, the repeater UE 1604 may stop providing discovery broadcasts, and at 1618, may provide an indication to the remote UE 1602 that a Uu failure has occurred. At 1620, the relay UE 1604 and the gNB 1606 may perform an RRC connection re - establishment procedure. At 1622, the remote UE 1602 may perform link reselection. At 1624, the relay UE 1604 may resume providing discovery broadcasts. At 1626, the remote UE 1602 may transmit a new RRC re - establishment request to the relay UE 1604 or possibly to another wireless device, for example, according to the result of link selection.

[0124] Figure 17is a signaling flow diagram showing aspects of an exemplary scenario according to some embodiments, where a remote RRC connection recovery fails due to a link failure between a relay UE and a gNB. As shown, in the illustrated scenario, at 1708, the remote UE 1702 may provide an RRC recovery request to the relay UE 1704. At 1710, the remote UE 1702 and the relay UE 1704 may be connected. At 1712, the relay UE 1704 may use the relay SRB to provide an RRC recovery request to the gNB 1706 and indicate the identification information of the remote UE 1702. At 1714, the gNB 1706 may use the relay SRB to provide an RRC recovery message to the relay UE 1704. At 1716, the relay UE 1704 may provide the RRC recovery message to the remote UE 1702. At 1718, the remote UE 1702 may connect to the gNB 1706. At 1720, the remote UE 1702 may attempt to complete the RRC recovery process with the gNB 1706 by providing an RRC recovery complete message to the relay UE 1704, and at 1722, the relay UE 1704 may use the relay SRB to provide an RRC recovery complete message to the gNB 1706 and indicate the identification information of the remote UE 1702. However, the delivery of the RRC recovery complete message may fail, and at 1724, the relay UE 1704 may declare a Uu link RLF. At 1726, the relay UE 1704 may stop providing discovery broadcasts, and at 1728, may provide an indication to the remote UE 1702 to suspend the relay link between the remote UE 1702 and the relay UE 1704. At 1730, the remote UE 1702 may enter the inactive mode. At 1732, the relay UE 1704 and the gNB 1706 may perform an RRC connection re-establishment process. At 1734, the remote UE 1702 may perform link reselection. At 1736, the relay UE 1704 may resume providing discovery broadcasts. At 1738, the remote UE 1702 may transmit a new RRC recovery request to the relay UE 1704 or possibly to another wireless device, e.g., according to the result of link selection.

[0125] In addition to detecting Uu link failures, it may also be useful to provide relay link failure detection and handling techniques. As one such possibility, for two-way RRC procedures (e.g., where RRC messages are provided in both the uplink and the downlink), the relay UE may be able to rely on a validity timer to control RRC response messages from the remote UE over the relay link. For example, Figure 18Shows aspects of an exemplary scenario according to some embodiments, where a relay UE uses a response validity timer to detect a link failure between the relay UE and a remote UE; as shown, in the illustrated scenario, in 1808, the remote UE 1802 and the relay UE 1804 can be initially connected. In 1810, the gNB 1806 can provide an RRC reconfiguration message to the relay UE 1804 using a relay SRB. The RRC reconfiguration message can include identification information of the remote UE 1802. In 1812, the relay UE 1804 can provide the RRC reconfiguration message to the remote UE 1802, including at least some of the information received from the gNB 1806. In 1814, when sending an RRC message to the remote UE 1802, the relay UE 1804 can start the response validity timer. Note that when receiving a response from the remote UE 1802, the relay UE 1804 can stop the timer. In 1816, the remote UE 1802 can transmit an RRC reconfiguration complete message to the relay UE 1804, but the relay UE 1804 may not receive the message. In 1818, the response validity timer can expire, and the relay UE 1804 can consider that an RRC message transmission failure has occurred on the relay link. Note that such a response validity timer can be configured by the relay UE 1804 itself or by the gNB 1806, for example, in an RRC message.

[0126] Figure 19 Is a signal flow diagram showing aspects of an exemplary scenario according to some embodiments, where a relay UE uses a response validity timer to detect a PC5 interface failure between the relay UE and a remote UE. Figure 19 The scenario of can be similar in at least some aspects to Figure 18The scenario, but more specifically, the PC5 RRC message validity timer can be used to detect a relay link failure in the case of a relay link between a remote and a relay device over the PC5 interface. As shown, in the illustrated scenario, in 1908, the remote UE 1902 and the relay UE 1904 can be initially connected. In 1910, the gNB 1906 can provide the relay UE 1904 with an RRC reconfiguration message that may include an indication of the PC5 message validity timer configuration. In 1912, the relay UE 1904 can provide the remote UE 1902 with a PC5 reconfiguration message. In 1914, when sending the PC5 reconfiguration message to the remote UE 1902, the relay UE 1904 can start the response validity timer. Note that when receiving a response from the remote UE 1902, the relay UE 1904 can stop the timer. In 1916, the remote UE 1902 can transmit a PC5 reconfiguration complete message to the relay UE 1904, but the relay UE 1904 may not receive the message. In 1918, the response validity timer can expire, and the relay UE 1904 can consider that a relay link failure has occurred. Note that such a PC5 RRC message validity timer can be configured by the relay UE 1904 itself or by the gNB 1906, for example, in the RRC message, as shown. Also note that, in a general sense, in the case where the two UEs are equivalent UEs performing sidelink communication, this method can be used to detect a link failure of either UE. Additionally, note that such a method can be used in combination with any one of various PC5 RRC messages, such as PC5 reconfiguration (e.g., as shown), UE capability request, and / or any one of various other possible messages.

[0127] In at least some cases, a similar method of using a response timer to detect a relay link failure can also or alternatively be used by the remote UE. For example, for a two-way RRC procedure, the remote UE can also rely on the validity timer to control the RRC response message from the relay UE over the relay link. Figure 20Shows aspects of an exemplary scenario according to some embodiments, where, for a link failure between a remote UE and a relay UE, the remote UE uses a response protection timer. As shown, in the illustrated scenario, in 2008, the gNB 2006 may indicate the protection timer duration to the relay UE 2004, the relay UE 2002 may broadcast the protection timer duration as part of discovery (e.g., as a configuration parameter), or may send it to the remote UE as part of connection establishment. In 2010, the relay UE 2004 may be connected, and in 2012, the remote UE 2002 may be inactive. In 2014, the remote UE 2002 may provide an RRC resume request to the relay UE 2004, and in 2016, a response protection timer may be started, which may be stopped after the remote UE 2002 receives a response from the relay UE 2004. However, the RRC resume request transfer may fail, so in 2018, the response protection timer may expire, and a relay link transmission failure may be detected. In 2020, the remote UE 2002 may detect a relay link failure based on the relay link transmission failure. In 2022, the remote UE 2002 may perform link selection, and in 2024, may transmit an RRC resume request to attempt to resume the RRC connection with the gNB 2006 again, possibly to the relay UE 2004 or possibly to another wireless device, e.g., according to the result of the link selection. Note that the relay UE may reuse the current RRC timer (e.g., t319) as the protection timer for the remote UE, or the gNB may configure a different expiration duration for the remote UE (e.g., as in the illustrated scenario), or the relay UE may autonomously configure the protection timer duration among various possibilities for determining the protection timer duration.

[0128] When the relay UE detects a relay link failure, e.g., using a timer-based method as in Figures 18 to 19 the illustrated scenario, or using any one of various other possible methods (e.g., based on RLC failure, radio link failure detection based on radio link monitoring, etc.), the relay UE may notify the network of the relay link failure according to at least some embodiments. In such a scenario, the network may be able to immediately terminate the current RRC procedure with the remote UE, and the relay UE may delete the remote UE, e.g., by itself or according to network configuration.

[0129] Figures 21 to 23 Is a signal flow diagram showing aspects of link failure handling for various exemplary scenarios according to some embodiments, where the remote RRC procedure fails due to a link failure between the relay UE and the remote UE.

[0130] More specifically, Figure 21is a signaling flow diagram showing aspects of an exemplary scenario according to some embodiments, where remote RRC connection establishment fails due to a link failure between a relay UE and a remote UE. As shown, in the illustrated scenario, at 2108, the remote UE 2102 may provide an RRC connection request to the relay UE 2104. At 2110, the remote UE 2102 and the relay UE 2104 may be connected. At 2112, the relay UE 2104 may use a relay SRB to provide an RRC connection request to the gNB 2106 and indicate the identification information of the remote UE 2102. At 2114, the gNB 2106 may use the relay SRB to provide an RRC connection establishment message to the relay UE 2104. At 2116, the relay UE 2104 may provide an RRC connection setup message to the remote UE 2102. At 2118, the remote UE 2102 may connect to the gNB 2106. At 2120, the remote UE 2102 may attempt to complete the RRC connection establishment with the gNB 2106 by providing an RRC setup complete message to the relay UE 2104. However, the delivery of the RRC setup complete message may fail, and at 2122, the remote UE 2102 may detect a relay link failure. At 2124, the remote UE 2102 may perform link selection, and at 2126, an attempt may be triggered to re-establish the RRC connection using the newly selected link. At 2128, the relay UE 2104 may also detect a relay link failure. At 2130, the relay UE 2104 may provide a remote UE relay link transmission failure indication to the gNB 2106, which may indicate the identification information of the remote UE 2102. At 2132, the gNB 2106 may terminate the connection establishment process, and at 2134, a remove remote UE message may be provided to the relay UE 2104, including an indication of the identification information for the remote UE 2102.

[0131] Figure 22Shows some aspects of an exemplary scenario according to some embodiments, where the re - establishment of a remote RRC connection fails due to a link failure between a relay UE and a remote UE. As shown, in the illustrated scenario, at 2208, the remote UE 2202 may provide an RRC re - establishment request to the relay UE 2204. At 2210, the remote UE 2202 and the relay UE 2204 may be connected. At 2212, the relay UE 2204 may use the relay SRB to provide an RRC re - establishment request to the gNB 2206 and indicate the identification information of the remote UE 2202. At 2214, the gNB 2206 may use the relay SRB to provide an RRC re - establishment message to the relay UE 2204. At 2216, the relay UE 2204 may provide the RRC re - establishment message to the remote UE 2202. However, the delivery of the RRC re - establishment message may fail, and at 2218, the relay UE 2204 may detect a relay link failure. At 2220, the relay UE 2204 may provide an indication (e.g., as a best action) to release the relay link to the remote UE 2202. At 2222, the remote UE 2202 may perform link selection, and at 2224, an attempt may be triggered to re - establish the RRC connection by using the newly selected link again. At 2226, the relay UE 2204 may provide a remote UE relay link transmission failure indication to the gNB 2206, which may indicate the identification information of the remote UE 2202. At 2228, the gNB 2206 may terminate the re - establishment process, and at 2230, may provide a remove remote UE message to the relay UE 2204, including an indication of the identification information for the remote UE 2202.

[0132] Figure 23Shows some aspects of an exemplary scenario according to some embodiments, where a remote RRC connection recovery failure occurs due to a link failure between a relay UE and a remote UE. As shown, in the illustrated scenario, at 2308, the remote UE 2302 may provide an RRC recovery request to the relay UE 2304. At 2310, the remote UE 2302 and the relay UE 2304 may be connected. At 2312, the relay UE 2304 may use the relay SRB to provide an RRC recovery request to the gNB 2306 and indicate the identification information of the remote UE 2302. At 2314, the gNB 2306 may use the relay SRB to provide an RRC recovery message to the relay UE 2304. At 2316, the relay UE 2304 may provide the RRC recovery message to the remote UE 2302. At 2318, the remote UE 2302 may connect to the gNB 2306. At 2320, the remote UE 2302 may attempt to complete the RRC recovery process with the gNB 2304 by providing an RRC recovery complete message to the relay UE 2306. However, the RRC recovery message delivery may fail, and at 2322, the remote UE 2302 may detect a relay link failure. At 2324, the remote UE 2302 may perform link selection, and at 2326, an attempt may be triggered to re-establish the RRC connection using the newly selected link. At 2328, the relay UE 2304 may also detect a relay link failure. At 2330, the relay UE 2304 may provide an indication of a remote UE relay link transmission failure to the gNB 2306, which may indicate the identification information of the remote UE 2302. At 2332, the gNB 2306 may terminate the recovery process, and at 2334, a remove remote UE message may be provided to the relay UE 2304, including an indication of the identification information for the remote UE 2302.

[0133] In the following, additional exemplary embodiments are provided.

[0134] A set of embodiments may include an apparatus that includes: a processor configured to cause a relay radio device to: establish a radio resource control connection with a cellular base station; receive a radio resource control connection request from a remote radio device; and relay radio resource control messages between the remote radio device and the cellular base station.

[0135] According to some embodiments, the processor is further configured to cause the relay radio device to: transmit a discovery broadcast message indicating that the relay radio device supports relay radio resource control messages; wherein at least in part based on receiving a radio resource control connection request from the remote radio device in response to the discovery broadcast message.

[0136] According to some embodiments, the processor is further configured to cause the relay wireless device to: detect a link failure of a wireless link between the relay wireless device and the cellular base station; and provide an indication of the link failure of the wireless link between the relay wireless device and the cellular base station to the remote wireless device.

[0137] According to some embodiments, the indication of the link failure of the wireless link between the relay wireless device and the cellular base station includes one or more of the following: an indication that a link failure has occurred in the wireless link between the relay wireless device and the cellular base station; an indication to suspend the wireless link between the relay wireless device and the remote wireless device; or an indication to release the wireless link between the relay wireless device and the remote wireless device.

[0138] According to some embodiments, the processor is further configured to cause the relay wireless device to: stop providing discovery broadcast messages to the remote wireless device at least in part based on the link failure of the wireless link between the relay wireless device and the cellular base station.

[0139] According to some embodiments, the processor is further configured to cause the relay wireless device to: detect a link failure of the wireless link between the relay wireless device and the remote wireless device; and provide an indication of the link failure of the wireless link between the relay wireless device and the remote wireless device to the cellular base station.

[0140] According to some embodiments, the processor is further configured to cause the relay wireless device to: receive an indication to release the remote wireless device from the cellular base station in response to an indication of a link failure of the wireless link between the relay wireless device and the remote wireless device.

[0141] According to some embodiments, the processor is further configured to cause the relay wireless device to: start a response validity timer at least in part based on relaying radio resource control messages to the remote wireless device; and detect a link failure of the wireless link between the relay wireless device and the remote wireless device based on the expiration of the response validity timer.

[0142] According to some embodiments, the processor is further configured to cause the relay wireless device to: relay radio resource control messages between the cellular base station and each of a plurality of remote wireless devices, wherein each radio resource control message relayed between the cellular base station and a corresponding remote wireless device includes remote wireless device identification information for the corresponding remote wireless device.

[0143] Another set of embodiments may include a cellular base station comprising: an antenna; radio components operatively coupled to the antenna; and a processor operatively coupled to the radio components; wherein the cellular base station is configured to: receive a radio resource control message from a relay wireless device, wherein the radio resource control message includes information relayed by the relay wireless device from a remote wireless device to the cellular base station; and transmit the radio resource control message to the relay wireless device, wherein the radio resource control message includes information configured to be relayed by the relay wireless device to the remote wireless device.

[0144] According to some embodiments, the radio resource control message includes a radio resource control connection establishment request, wherein the radio resource control message includes a radio resource control connection setup message.

[0145] According to some embodiments, the radio resource control message includes a radio resource control connection re - establishment request, wherein the radio resource control message includes a radio resource control re - establishment message.

[0146] According to some embodiments, the radio resource control message includes a radio resource control connection resume request, wherein the radio resource control message includes a radio resource control resume message.

[0147] According to some embodiments, the cellular base station is further configured to: transmit a radio resource control release message to the relay wireless device, wherein the radio resource control release message is configured to be relayed by the relay wireless device to the remote wireless device.

[0148] According to some embodiments, the cellular base station is further configured to: transmit a radio resource control reconfiguration message to the relay wireless device, wherein the radio resource control reconfiguration message is configured to be relayed by the relay wireless device to the remote wireless device.

[0149] Another set of embodiments may include a method that includes: by a first wireless device: providing a first radio resource control message to a second wireless device, wherein the first radio resource control message includes information configured to be relayed by the second wireless device to a cellular base station; and receiving a second radio resource control message from the second wireless device, wherein the second radio resource control message includes information relayed by the second wireless device from the cellular base station to the first wireless device.

[0150] According to some embodiments, the method further includes: performing link selection to determine a radio link on which to attempt to establish a radio resource control connection for relaying to the cellular base station, and providing the first radio resource control message to the second wireless device at least partially based on the link selection.

[0151] According to some embodiments, the method further includes: starting a response protection timer at least partially based on providing a radio resource control message to a second wireless device, wherein the response protection timer is stopped when a response to the resource control message is received from the second wireless device; determining that a link failure of a wireless link between the first wireless device and the second wireless device has occurred at least partially based on expiration of the response protection timer; and performing link selection at least partially based on the link failure of the wireless link between the first wireless device and the second wireless device to determine a wireless link on which to attempt to establish a radio resource control connection for relaying with a cellular base station.

[0152] According to some embodiments, the method further includes: receiving an indication to release a wireless link between the first wireless device and the second wireless device, and performing link selection at least partially based on the indication to release the wireless link between the first wireless device and the second wireless device to determine a wireless link on which to attempt to establish a radio resource control connection for relaying with a cellular base station.

[0153] According to some embodiments, the first radio resource control message includes one of the following: a radio resource control connection establishment request; a radio resource control connection reestablishment request; or a radio resource control connection resume request.

[0154] Another exemplary embodiment may include a method, including: by a wireless device: performing any or all parts of the foregoing examples.

[0155] Another exemplary embodiment may include a wireless device, the wireless device including: an antenna; radio components coupled to the antenna; and a processing element operably coupled to the radio components, wherein the device is configured to implement any part or all parts of the foregoing examples.

[0156] Another exemplary embodiment may include a device, the device including: a processing element configured to cause a wireless device to implement any or all parts of the foregoing examples.

[0157] Another exemplary set of embodiments may include a non-transitory computer-accessible memory medium, which includes program instructions that, when executed at a device, cause the device to implement any or all parts of any one of the foregoing examples.

[0158] Another exemplary set of embodiments may include a computer program including instructions for performing any or all parts of any one of the foregoing examples.

[0159] Another exemplary set of embodiments may include a device, the device including means for performing any or all elements of any one of the foregoing examples.

[0160] As is well known, the use of personally identifiable information should comply with privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of accidental or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0161] In addition to the above exemplary embodiments, more embodiments of the present disclosure can be implemented in any of a variety of forms. For example, some embodiments can be implemented as computer-implemented methods, computer-readable memory media, or computer systems. Other embodiments can be implemented using one or more custom-designed hardware devices such as ASICs. Still other embodiments can be implemented using one or more programmable hardware elements such as FPGAs.

[0162] In some embodiments, a non-transitory computer-readable memory medium can be configured such that it stores program instructions and / or data, where if the program instructions are executed by a computer system, the computer system is caused to execute a method, such as any of the 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.

[0163] In some embodiments, a device (e.g., UE 106 or 107) can 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 can be implemented in any of a variety of forms.

[0164] Although the above embodiments have been described in considerable detail, many variations and modifications will become apparent to those skilled in the art once the above disclosure is fully understood. The present invention is intended that the following claims be construed to cover all such variations and modifications.

Claims

1. A method for wireless communication, comprising: By a relay wireless device: Relaying radio resource control (RRC) messages between a cellular base station and a remote wireless device to establish an RRC connection with the cellular base station; Determining a radio link failure in the Uu link; Transmitting an indication of the radio link failure in the Uu link to the remote wireless device so that the remote wireless device performs link selection.

2. The method according to claim 1, further comprising: Transmitting a discovery broadcast message indicating that the relay wireless device supports relaying RRC messages; Wherein, the RRC connection is established at least in part in response to the discovery broadcast message.

3. The method according to claim 1, further comprising: Stopping transmitting the discovery broadcast message to the remote wireless device at least in part based on the radio link failure of the Uu link.

4. The method according to claim 1, wherein the indication of the radio link failure in the Uu link comprises one or more of the following: An indication that a radio link failure has occurred in the Uu link; An indication to suspend the wireless link between the relay wireless device and the remote wireless device; Or An indication to release the wireless link between the relay wireless device and the remote wireless device.

5. The method according to claim 1, further comprising: Providing a second indication of the radio link failure of the Uu link to the cellular base station.

6. The method according to claim 5, further comprising: Receiving an indication to release the remote wireless device from the cellular base station in response to the second indication of the radio link failure of the Uu link.

7. The method according to claim 1, further comprising: Receiving an RRC reestablishment request from a remote UE; And Relaying the RRC reestablishment request to the cellular base station, wherein the RRC reestablishment request is relayed to the cellular base station together with an identifier of the remote UE.

8. A device for wireless communication, comprising: A processor configured to cause a relay wireless device to: Relay radio resource control (RRC) messages between a cellular base station and a remote wireless device to establish an RRC connection with the cellular base station; Determine a radio link failure in the Uu link; Transmit an indication of the radio link failure in the Uu link to the remote wireless device so that the remote wireless device performs link selection.

9. The device according to claim 8, wherein the processor is further configured to cause the relay wireless device to: Transmit a discovery broadcast message indicating that the relay wireless device supports relaying RRC messages; Among them, Establish the RRC connection at least in part in response to the discovery broadcast message.

10. The device according to claim 8, wherein the processor is further configured to cause the relay wireless device to: Stop transmitting the discovery broadcast message to the remote wireless device at least in part based on the radio link failure of the Uu link.

11. The apparatus according to claim 8, wherein the indication of radio link failure in the Uu link comprises one or more of the following: An indication that radio link failure has occurred in the Uu link; An indication to suspend the radio link between the relay radio device and the remote radio device; Or An indication to release the radio link between the relay radio device and the remote radio device.

12. The apparatus according to claim 8, wherein the processor is further configured to cause the relay radio device to: Provide a second indication of radio link failure of the Uu link to the cellular base station.

13. The apparatus according to claim 12, wherein the processor is further configured to cause the relay radio device to: In response to the second indication of radio link failure of the Uu link, receive an indication to release the remote radio device from the cellular base station.

14. The apparatus according to claim 8, wherein the processor is further configured to cause the relay radio device to: Receive an RRC reestablishment request from a remote UE; and Relay the RRC reestablishment request to the cellular base station, wherein the RRC reestablishment request is relayed to the cellular base station together with the identifier of the remote UE.

15. An apparatus for wireless communication, comprising: A processor configured to cause a remote radio device to: Exchange radio resource (RRC) messages with a cellular base station via a relay radio device to establish an RRC connection with the cellular base station, wherein the relay radio device is connected to the cellular base station via a Uu link; Receive an indication of radio link failure in the Uu link from the relay radio device; Perform link selection in response to the indication.

16. The apparatus according to claim 15, wherein the remote radio device is further configured to: Receive a discovery broadcast message from the relay device, the discovery broadcast message indicating that the relay radio device supports relaying RRC messages; Among them, Exchange the RRC messages with the cellular base station at least in part in response to the discovery broadcast message.

17. The apparatus according to claim 15, wherein the indication of radio link failure in the Uu link comprises one or more of the following: An indication that radio link failure has occurred in the Uu link; An indication to suspend the radio link between the relay radio device and the remote radio device; Or An indication to release the radio link between the relay radio device and the remote radio device.

18. The apparatus according to claim 15, wherein the remote radio device is further configured to: Perform link reselection in response to receiving an indication of radio link failure in the Uu link.

19. The apparatus according to claim 15, Wherein depending on the result of the link reselection, transmit the RRC reestablishment request to the relay radio device or another radio device.

20. The apparatus according to claim 15, Wherein the cellular base station includes a 5th Generation New Radio (5G NR) gNodeB (gNB).

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