PATENT DOCUMENT

Publication Number: US-11477676-B2
Application Number: US-201917289013-A
Country: US
Kind Code: B2

Title: RLM enhancements for 5G networks

Abstract:
An apparatus of user equipment (UE) includes processing circuitry coup led to a memory, where to configure the UE for radio link monitoring (RLM) in a New Radio-Unlicensed (NR-U) network, the processing circuitry is to decode radio resource control (RRC) signaling from a base station. The RRC signaling includes configuration information to configure transmission occasions for a plurality of RLM reference signals (RLM-RSs). A primary synchronization signal (PSS) or a secondary synchronization signal (SSS) detection is performed to determine a number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions. Signal measurements are performed on the RLM-RSs that are successfully transmitted within an evaluation duration to determine a block error rate (BLER). The signal measurements are performed when the number is higher than a threshold number. An in-sync (IS) indicator or an out-of-sync (OOS) indicator are generated based on the signal measurements.

Claims:
What is claimed is: 
     
       1. An apparatus of a user equipment (UE), the apparatus comprising:
 processing circuitry, wherein to configure the UE for radio link monitoring (RLM) in a New Radio-Unlicensed (NR-U) network, the processing circuitry is to:
 decode radio resource control (RRC) signaling from a base station, the RRC signaling including configuration information to configure one or more transmission occasions for a plurality of RLM reference signals (RLM-RSs); 
 perform a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) or a physical broadcast channel (PBCH) detection to determine a number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within an evaluation duration; 
 perform signal measurements on the first RLM-RSs that are successfully transmitted within the evaluation duration to determine a hypothetical block error rate (BLER) for physical downlink control channel (PDCCH) reception, the signal measurements performed during the transmission occasions within the evaluation duration; and 
 generate based on the signal measurements, one of an in-sync (IS) indicator or an out-of-sync (OOS) indicator for communication to a higher layer; 
 generate a transmission failure (TXT) indicator when the number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within the evaluation duration is zero or is smaller than a threshold number, the threshold number configured by higher layer signaling; and 
 
 memory coupled to the processing circuitry and configured to store the signal measurements. 
 
     
     
       2. The apparatus of  claim 1 , wherein the processing circuitry is to:
 upon generating a total of N 312  number of consecutive TXF indicators including the TXF indicator, start a radio link failure (RLF) timer T 310 , 
 wherein N 312  and the T 310  timer are configured by higher layer signaling. 
 
     
     
       3. The apparatus of  claim 2 , wherein the processing circuitry is to:
 initiate an RLF procedure upon expiration of the RLF timer T 310 . 
 
     
     
       4. The apparatus of  claim 2 , wherein the processing circuitry is to:
 upon generating a total of N 311  number of consecutive IS indicators without a TXF indicator, stopping the RLF timer T 310 . 
 
     
     
       5. The apparatus of  claim 1 , wherein the evaluation duration comprises a first pre-configured time duration, and wherein the processing circuitry is to:
 when the number is higher than the threshold number, perform an evaluation on the BLER for a subset of the RLM-RSs that are successfully transmitted within the first pre-configured time duration within the transmission occasions; and 
 generate the OOS indicator when the BLER for a number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted within the first pre-configured time duration is higher than an OOS threshold. 
 
     
     
       6. The apparatus of  claim 5 , wherein the evaluation duration comprises a second pre-configured time duration, and wherein the processing circuitry is to:
 when the number is higher than the threshold number, perform an evaluation on the BLER for a subset of the RLM-RSs that are successfully transmitted within the second pre-configured time duration within the transmission occasions; and 
 generate the IS indicator when the BLER for the number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted within the second pre-configured time duration is lower than an IS threshold. 
 
     
     
       7. The apparatus of  claim 6 , wherein the threshold number, the OOS threshold, and the IS threshold are configured by the RRC signaling. 
     
     
       8. The apparatus of  claim 1 , wherein the processing circuitry is to:
 perform a physical broadcast channel (PBCH) detection to determine the number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions. 
 
     
     
       9. The apparatus of  claim 1 , wherein the processing circuitry is to:
 for each transmission occasion within the evaluation duration, encode for transmission to the base station at least one of the following: the TXF indicator, an indicator of absence of a TXF during the transmission occasion, and a reference signal received power (RSRP) associated with an RLM-RS of the plurality of RLM-RSs received during the transmission occasion. 
 
     
     
       10. The apparatus of  claim 1 , further comprising transceiver circuitry coupled to the processing circuitry; and, one or more antennas coupled to the transceiver circuitry. 
     
     
       11. A computer-readable non-transitory storage medium that stores instructions for execution by one or more processors of a user equipment (UE), the instructions to configure the UE for radio link monitoring (RLM) in a New Radio-Unlicensed (NR-U) network, and to cause the UE to:
 decode radio resource control (RRC) signaling from a base station, the RRC signaling including configuration information to configure transmission occasions for a plurality of RLM reference signals (RLM-RSs); 
 perform a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) detection to determine a number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within an evaluation duration; 
 perform signal measurements on the first RLM-RSs that are successfully transmitted within the evaluation duration to determine a hypothetical block error rate (BLER) for physical downlink control channel (PDCCH) reception, the signal measurements performed when the number is higher than a threshold number; 
 generate a transmission failure (TXT) indicator when the number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within the evaluation duration is zero or is smaller than a threshold number, the threshold number configured by higher layer signaling; and 
 generate based on the signal measurements, one of an in-sync (IS) indicator or an out-of-sync (OOS) indicator for communication to a higher layer. 
 
     
     
       12. The computer-readable non-transitory storage medium of  claim 11 , wherein the instructions further cause the UE to:
 upon generating a total of N 312  number of consecutive TXF indicators including the TXF indicator, start a radio link failure (RLF) timer T 310 ; and 
 initiate an RLF procedure upon expiration of the RLF timer T 310 , wherein N 312  and the T 310  timer are configured by higher layer signaling. 
 
     
     
       13. The computer-readable non-transitory storage medium of  claim 12 , wherein the instructions further cause the UE to:
 upon generating a total of N 311  number of consecutive IS indicators without a TXF indicator, stopping the RLF timer T 310 . 
 
     
     
       14. The computer-readable non-transitory storage medium of  claim 11 , wherein the evaluation duration comprises a first pre-configured time duration, and wherein the instructions further cause the UE to:
 when the number is higher than the threshold number, perform an evaluation on the BLER for a subset of the RLM-RSs that are successfully transmitted within the first pre-configured time duration within the transmission occasions; and 
 generate the OOS indicator when the BLER for a number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted within the first pre-configured time duration is higher than an OOS threshold. 
 
     
     
       15. The computer-readable non-transitory storage medium of  claim 14 , wherein the evaluation duration comprises a second pre-configured time duration, and wherein the instructions further cause the UE to:
 when the number is higher than the threshold number, perform an evaluation on the BLER for a subset of the RLM-RSs that are successfully transmitted within the second pre-configured time duration within the transmission occasions; and 
 generate the IS indicator when the BLER for the number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted within the second pre-configured time duration is lower than an IS threshold. 
 
     
     
       16. The computer-readable non-transitory storage medium of  claim 11 , wherein the instructions further cause the UE to:
 perform a physical broadcast channel (PBCH) detection to determine the number of RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions. 
 
     
     
       17. A method, comprising:
 by a user equipment (UE): 
 wherein to configure the UE for radio link monitoring (RLM) in a New Radio-Unlicensed (NR-U) network, the processing circuitry is to:
 decoding radio resource control (RRC) signaling from a base station, the RRC signaling including configuration information to configure one or more transmission occasions for a plurality of RLM reference signals (RLM-RSs); 
 performing a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) or a physical broadcast channel (PBCH) detection to determine a number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within an evaluation duration; 
 performing signal measurements on the first RLM-RSs that are successfully transmitted within the evaluation duration to determine a hypothetical block error rate (BLER) for physical downlink control channel (PDCCH) reception, the signal measurements performed during the transmission occasions within the evaluation duration; and 
 generating based on the signal measurements, one of an in-sync (IS) indicator or an out-of-sync (OOS) indicator for communication to a higher layer; 
 generating a transmission failure (TXT) indicator when the number of first RLM-RSs of the plurality of RLM-RSs that are successfully transmitted during the transmission occasions within the evaluation duration is zero or is smaller than a threshold number, the threshold number configured by higher layer signaling; and 
 
 storing the signal measurements in a non-transitory computer-readable storage medium. 
 
     
     
       18. The method of  claim 17 , further comprising:
 upon generating a total of N 312  number of consecutive TXF indicators including the TXF indicator, starting a radio link failure (RLF) timer T 310 , 
 wherein N 312  and the T 310  timer are configured by higher layer signaling. 
 
     
     
       19. The method of  claim 18 , further comprising:
 initiating an RLF procedure upon expiration of the RLF timer T 310 . 
 
     
     
       20. The method of  claim 18 , further comprising:
 upon generating a total of N 311  number of consecutive IS indicators without a TXF indicator, stopping the RLF timer T 310 .

Description:
PRIORITY CLAIM 
     This application is a U.S. National Stage filing of International Application No. PCT/US2019/058557, filed Oct. 29, 2019, entitled “RLM ENHANCEMENTS FOR 5G NETWORKS”, which claims the benefit of priority to the U.S. Provisional Patent Application Ser. No. 62/755,346, filed Nov. 2, 2018, and entitled “RADIO LINK MONITORING (RLM) ENHANCEMENT FOR NEW RADIO,” each of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Aspects pertain to wireless communications. Some aspects relate to wireless networks including 3GPP (Third Generation Partnership Project) networks, 3GPP LTE (Long Term Evolution) networks, 3GPP LTE-A (LTE Advanced) networks, and fifth-generation (5G) networks including 5G new radio (NR) (or 5G-NR) networks, 5G-LTE networks, and 5G NR unlicensed spectrum (NR-U) networks. Other aspects are directed to systems and methods for RLM enhancements for 5G networks including NR-U networks. 
     BACKGROUND 
     Mobile communications have evolved significantly from early voice systems to today&#39;s highly sophisticated integrated communication platform. With the increase in different types of devices communicating with various network devices, usage of 3GPP LTE systems has increased. The penetration of mobile devices (user equipment or UEs) in modern society has continued to drive demand for a wide variety of networked devices in a number of disparate environments. Fifth-generation (5G) wireless systems are forthcoming and are expected to enable even greater speed, connectivity, and usability. Next generation 5G networks (or NR networks) are expected to increase throughput, coverage, and robustness and reduce latency and operational and capital expenditures. 5G-NR networks will continue to evolve based on 3GPP LTE-Advanced with additional potential new radio access technologies (RATs) to enrich people&#39;s lives with seamless wireless connectivity solutions delivering fast, rich content and services. As current cellular network frequency is saturated, higher frequencies, such as millimeter wave (mmWave) frequency, can be beneficial due to their high bandwidth. 
     Potential LTE operation in the unlicensed spectrum includes (and is not limited to) the LTE operation in the unlicensed spectrum via dual connectivity (DC), or DC-based LAA, and the standalone LTE system in the unlicensed spectrum, according to which LTE-based technology solely operates in unlicensed spectrum without requiring an “anchor” in the licensed spectrum, called MulteFire. MulteFire combines the performance benefits of LTE technology with the simplicity of Wi-Fi-like deployments. 
     Further enhanced operation of LTE systems in the licensed as well as unlicensed spectrum is expected in future releases and 5G systems. Such enhanced operations can include techniques for SR enhancements for 5G networks including NR-U networks. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the figures, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The figures illustrate generally, by way of example, but not by way of limitation, various aspects discussed in the present document. 
         FIG. 1A  illustrates an architecture of a network, in accordance with some aspects. 
         FIG. 1B  and  FIG. 1C  illustrate a non-roaming 5G system architecture in accordance with some aspects. 
         FIG. 2  illustrates radio link monitoring reference signal (RLM-RS) transmissions and various RLM-related parameters for communications within a licensed spectrum without listen-before-talk (LBT), in accordance with some aspects. 
         FIG. 3  illustrates RLM-RS transmissions and various RLM-related parameters for communications within an unlicensed spectrum where RLM-RS is subject to LBT, in accordance with some aspects. 
         FIG. 4  illustrates UE reporting options of a detected transmission failure (TXF) occasions of RLM-RS, in accordance with some aspects. 
         FIG. 5  illustrates a signal-to-interference-plus-noise ratio (SINR) range where detection of TXF is beneficial in order to not trigger falls radio link failure (RLF), in accordance with some aspects. 
         FIG. 6  illustrates a block diagram of a communication device such as an evolved. Node-B (eNB), a new generation Node-B (gNB), an access point (AP), a wireless station (STA), a mobile station (MS), or a user equipment (UE), in accordance with some aspects. 
     
    
    
     DETAILED DESCRIPTION 
     The following description and the drawings sufficiently illustrate aspects to enable those skilled in the art to practice them. Other aspects may incorporate structural, logical, electrical, process, and other changes. Portions and features of some aspects may be included in or substituted for, those of other aspects. Aspects set forth in the claims encompass all available equivalents of those claims. 
       FIG. 1A  illustrates an architecture of a network in accordance with some aspects. The network  140 A is shown to include user equipment (UE)  101  and UE  102 . The UEs  101  and  102  are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks) but may also include any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, drones, or any other computing device including a wired and/or wireless communications interface. The UEs  101  and  102  can be collectively referred to herein as UE  101 , and UE  101  can be used to perform one or more of the techniques disclosed herein. 
     Any of the radio links described herein (e.g., as used in the network  140 A or any other illustrated network) may operate according to any exemplary radio communication technology and/or standard. 
     LTE and LTE-Advanced are standards for wireless communications of high-speed data for UE such as mobile telephones. In LTE-Advanced and various wireless systems, carrier aggregation is a technology according to which multiple carrier signals operating on different frequencies may be used to carry communications for a single UT, thus increasing the bandwidth available to a single device. In some aspects, carrier aggregation may be used where one or more component carriers operate on unlicensed frequencies. 
     Aspects described herein can be used in the context of any spectrum management scheme including, for example, dedicated licensed spectrum, unlicensed spectrum, (licensed) shared spectrum (such as Licensed Shared Access (LSA) in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz, and further frequencies and Spectrum Access System (SAS) in 3.55-3.7 GHz and further frequencies). 
     Aspects described herein can also be applied to different Single Carrier or OFDM flavors (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-based multicarrier (FBMC), OFDMA, etc.) and in particular 3GPP NR (New Radio) by allocating the OFDM carrier data bit vectors to the corresponding symbol resources. 
     In some aspects, any of the UEs  101  and  102  can comprise an Internet-of-Things (IoT) UE or a Cellular IoT (CIoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. In some aspects, any of the UEs  101  and  102  can include a narrowband (NB) IoT UE (e.g., such as an enhanced NB-IoT (eNB-IoT) UE and Further Enhanced (FeNB-IoT) UE). An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network includes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network. 
     In some aspects, any of the UEs  101  and  102  can include enhanced MTC (eMTC) UEs or further enhanced MTC (FeMTC) UEs. 
     The UEs  101  and  102  may be configured to connect, e.g., communicatively couple, with a radio access network (RAN)  110 . The RAN  110  may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs  101  and  102  utilize connections  103  and  104 , respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections  103  and  104  are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth-generation (5G) protocol, a New Radio (NR) protocol, and the like. 
     In an aspect, the UEs  101  and  102  may further directly exchange communication data via a ProSe interface  105 . The ProSe interface  105  may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH). 
     The UE  102  is shown to be configured to access an access point (AP)  106  via connection  107 . The connection  107  can comprise a local wireless connection, such as, for example, a connection consistent with any IEEE 802.11 protocol, according to which the AP  106  can comprise a wireless fidelity (WiFi®) router. In this example, the AP  106  is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below). 
     The RAN  110  can include one or more access nodes that enable the connections  103  and  104 . These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), Next Generation NodeBs (gNBs), RAN nodes, and the like, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). In some aspects, the communication nodes  111  and  112  can be transmission/reception points (TRPs). In instances when the communication nodes  111  and  112  are NodeBs (e.g., eNBs or gNBs), one or more TRPs can function within the communication cell of the NodeBs. The RAN  110  may include one or more RAN nodes for providing macrocells, e.g., macro RAN node  111 , and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node  112 . 
     Any of the RAN nodes  111  and  112  can terminate the air interface protocol and can be the first point of contact for the UEs  101  and  102 . In some aspects, any of the RAN nodes  111  and  112  can fulfill various logical functions for the RAN  110  including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In an example, any of the nodes  111  and/or  112  can be a new generation Node-B (gNB), an evolved node-B (eNB), or another type of RAN node. 
     The RAN  110  is shown to be communicatively coupled to a core network (CN)  120  via an S 1  interface  113 . In aspects, the CN  120  may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN (e.g., as illustrated in reference to  FIGS. 1B-1I ). In this aspect, the S 1  interface  113  is split into two parts: the S 1 -U interface  114 , which carries traffic data between the RAN nodes  111  and  112  and the serving gateway (S-GW)  122 , and the S 1 -mobility management entity (MMF) interface  115 , which is a signaling interface between the RAN nodes  111  and  112  and MMEs  121 . 
     In this aspect, the CN  120  comprises the MMEs  121 , the S-GW  122 , the Packet Data Network (PDN) Gateway (P-GW)  123 , and a home subscriber server (HSS)  124 . The MMEs  121  may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs  121  may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS  124  may comprise a database for network users, including subscription-related information to support the network entities&#39; handling of communication sessions. The CN  120  may comprise one or several HSSs  124 , depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS  124  can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc. 
     The S-GW  122  may terminate the S 1  interface  113  towards the RAN  110 , and routes data packets between the RAN  110  and the CN  120 . In addition, the S-GW  122  may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities of the S-GW  122  may include a lawful intercept, charging, and some policy enforcement. 
     The P-GW  123  may terminate an SGi interface toward a PDN. The P-GW  123  may route data packets between the EPC network  120  and external networks such as a network including the application server  184  (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface  125 . The P-GW  123  can also communicate data to other external networks  131 A, which can include the Internet, IP multimedia subsystem (IPS) network, and other networks. Generally, the application server  184  may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this aspect, the P-GW  123  is shown to be communicatively coupled to an application server  184  via an IP interface  125 . The application server  184  can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs  101  and  102  via the CN  120 . 
     The P-GW  123  may further be a node for policy enforcement and charging data collection. Policy and Charging Rules Function (PCRF)  126  is the policy and charging control element of the CN  120 . In a non-roaming scenario, in some aspects, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE&#39;s Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with a local breakout of traffic, there may be two PCRFs associated with a UE&#39;s IP-CAN session: a Home PCRF (H-PCRF) within an HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF  126  may be communicatively coupled to the application server  184  via the P-GW  123 . 
     In some aspects, the communication network  140 A can be an IoT network or a 5G network, including 5G new radio network using communications in the licensed (5G NR) and the unlicensed (5G NR-U) spectrum. One of the current enablers of IoT is the narrowband-IoT (NB-IoT). 
     An NG system architecture can include the RAN  110  and a 5G network core (5GC)  120 . The NG-RAN  110  can include a plurality of nodes, such as gNBs and NG-eNBs. The core network  120  (e.g., a 5G core network or 5GC) can include an access and mobility function (AMF) and/or a user plane function (UPF). The AMF and the UPF can be communicatively coupled to the gNBs and the NG-eNBs via NG interfaces. More specifically, in some aspects, the gNBs and the NG-eNBs can be connected to the AMF by NG-C interfaces, and to the UPF by NG-U interfaces. The gNBs and the NG-eNBs can be coupled to each other via Xn interfaces. 
     In some aspects, the NG system architecture can use reference points between various nodes as provided by 3GPP Technical Specification (TS) 23.501 (e.g., V15.4.0, 2018-12). In some aspects, each of the gNBs and the NG-eNBs can be implemented as a base station, a mobile edge server, a small cell, a home eNB, and so forth. In some aspects, a gNB can be a master node (MN) and NG-eNB can be a secondary node (SN) in a 5G architecture. 
       FIG. 1B  illustrates a non-roaming 5G system architecture in accordance with some aspects. Referring to  FIG. 1B , there is illustrated a 5G system architecture  140 B in a reference point representation. More specifically, UE  102  can be in communication with RAN  110  as well as one or more other 5G core (5GC) network entities. The 5G system architecture  140 B includes a plurality of network functions (NFs), such as access and mobility management function (ANTE)  132 , session management function (SMF)  136 , policy control function (PCF)  148 , application function (AF)  150 , user plane function (UPF)  134 , network slice selection function (NSSF)  142 , authentication server function (AUSF)  144 , and unified data management (UDM)/home subscriber server (HSS)  146 . The UPF  134  can provide a connection to a data network (DN)  152 , which can include, for example, operator services, Internet access, or third-party services. The AMF  132  can be used to manage access control and mobility and can also include network slice selection functionality. The SMF  136  can be configured to set up and manage various sessions according to network policy. The UPF  134  can be deployed in one or more configurations according to the desired service type. The PCF M 8  can be configured to provide a policy framework using network slicing, mobility management, and roaming (similar to PCRF in a 4G communication system). The UDM can be configured to store subscriber profiles and data (similar to an HSS in a 4G communication system). 
     In some aspects, the 5G system architecture  140 B includes an IP multimedia subsystem (IMS)  168 B as well as a plurality of IP multimedia core network subsystem entities, such as call session control functions (CSCFs). More specifically, the IMS  168 B includes a CSCF, which can act as a proxy CSCF (P-CSCF)  162 BE, a serving CSCF (S-CSCF)  164 B, an emergency CSCF (E-CSCF) (not illustrated in  FIG. 1B ), or interrogating CSCF (I-CSCF)  166 B, The P-CSCF  162 B can be configured to be the first contact point for the UE  102  within the IM subsystem (IMS)  168 B. The S-CSCF  164 B can be configured to handle the session states in the network, and the E-CSCF can be configured to handle certain aspects of emergency sessions such as routing an emergency request to the correct emergency center or PSAP. The I-CSCF  166 B can be configured to function as the contact point within an operators network for all IMS connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator&#39;s service area. In some aspects, the I-CSCF  166 B can be connected to another IP multimedia network  170 E, e.g. an IMS operated by a different network operator. 
     In some aspects, the UDM/HSS  146  can be coupled to an application server  160 E, which can include a telephony application server (TAS) or another application server (AS). The AS  160 B can be coupled to the IMS  168 B via the S-CSCF  164 B or the I-CSCF  166 B. 
     A reference point representation shows that interaction can exist between corresponding NF services. For example,  FIG. 1B  illustrates the following reference points: N 1  (between the UE  102  and the AMF  132 ), N 2  (between the RAN  110  and the AMF  132 ), N 3  (between the RAN  110  and the UPF  134 ), N 4  (between the SMF  136  and the UPF  134 ), N 5  (between the PCF  148  and the AF  150 , not shown), N 6  (between the UPF  134  and the DN  152 ), N 7  (between the SMF  136  and the PCF  148 , not shown), N 8  (between the UDM  146  and the AMF  132 , not shown), N 9  (between two UPFs  134 , not shown), N 10  (between the UDM  146  and the SMF  136 , not shown), N 11  (between the AMF  132  and the SMF  136 , not shown), N 12  (between the AUSF  144  and the AMF  132 , not shown), N 13  (between the AUSF  144  and the UDM  146 , not shown), N 14  (between two AMFs  132 , not shown), N 15  (between the PCF  148  and the AMF  132  in case of a non-roaming scenario, or between the PCF  148  and a visited network and AMF  132  in case of a roaming scenario, not shown), N 16  (between two SMFs, not shown), and N 22  (between AMF  132  and NSSF  142 , not shown). Other reference point representations not shown in  FIG. 1E  can also be used. 
       FIG. 1C  illustrates a 5G system architecture  140 C and a service-based representation. In addition to the network entities illustrated in  FIG. 1B , system architecture  140 C can also include a network exposure function (NEF)  154  and a network repository function (NRF)  156 . In some aspects, 5G system architectures can be service-based and interaction between network functions can be represented by corresponding point-to-point reference points Ni or as service-based interfaces. 
     In some aspects, as illustrated in  FIG. 1C , service-based representations can be used to represent network functions within the control plane that enable other authorized network functions to access their services. In this regard, 5G system architecture  140 C can include the following service-based interfaces: Namf  158 H (a service-based interface exhibited by the AMF  132 ), Nsmf  158 I (a service-based interface exhibited by the SMF  136 ), Nnef  158 B (a service-based interface exhibited by the NEF  154 ), Npcf  158 D (a service-based interface exhibited by the PCF  148 ), a Nudm  158 E (a service-based interface exhibited by the UDM  146 ), Naf  158 F (a service-based interface exhibited by the AF  150 ), Nnrf  158 C (a service-based interface exhibited by the NRF  156 ), Nnssf  158 A (a service-based interface exhibited by the NSSF  142 ), Nausf  158 G (a service-based interface exhibited by the AUSF  144 ). Other service-based interfaces (e.g., Nudr, N5g-eir, and Nudsf) not shown in  FIG. 1C  can also be used. 
     Techniques discussed herein can be performed by a UE or a base station (e.g., any of the UEs or base stations illustrated in connection with  FIG. 1A - FIG. 1C ). 
     In NR-U communications, a radio link monitoring (RLM) feature may be needed for enabling stand-alone operation. In some aspects, RLM is based on measurements of a predictable and periodically transmitted signal from the serving gNB. Due to LBT requirements, it may not be feasible to transmit a periodic signal for RLM in a predictable fashion. 
     Techniques discussed herein can be used to provide an indication of transmission failure (TXF) that is determined at the UE in layer 1 (L1) as well as UE reporting to the gNB indicating certain transmission occasions of an RLM-RS has been detected as TXF. 
     RLM procedure in a licensed spectrum operation with no LBT. 
       FIG. 2  illustrates RLM-RS transmissions  200  and various RLM-related parameters for communications within a licensed spectrum without listen-before-talk (LBT), in accordance with some aspects. 
     In some aspects associated with licensed spectrum operation, a gNB is able to perform transmission without any LBT requirements. A UE performs RLM procedure in RRC CONNECTED state based on measurements performed on an RLM-RS. 
     As illustrated in  FIG. 2 , an RLM-RS  202  is periodically transmitted with a certain periodicity T RS    204 . The UE is aware of the RLM-RS configuration to be able to perform measurements on every transmission occasion of the RLM-RS within an evaluation window. The UE evaluates a hypothetical PDCCH block error rate (BLER) metric against an indicated threshold in L1. If the UE determines that the hypothetical PDCCH BLER is higher than a certain threshold (e.g., 10%), the UE may generate an out-of-sync (OOS) indication to the higher layer and/or to the base station. If the UE determines that the hypothetical PDCCH BLER is lower than a certain threshold (e.g., 2%), the UE may generate an in-sync (IS) indication to the higher layer and/or to the base station. 
     The evaluation window for OOS indication is governed by a certain time T Evaluate_out_RS    208  that captures a certain number of RLM-RS transmission occasions (3 shown in  FIG. 2 ). The evaluation window for IS indication is governed by a certain time T Evaluate_in_RS    206  that captures a certain number of RLM-RS transmission occasions (2 shown in  FIG. 2 ). Within the IS or OOS evaluation window, a UE may use implementation-specific algorithms for determining the BLER metric. For example, a UE may perform channel and interference measurements on all the transmission occasions of the RLM-RS, apply a hypothetical receiver model, apply filtering, determine SINR, determine mutual information, and predict a BLER based on the indicated hypothetical PDCCH configuration. A UE may also use additional information such as actual PDCCH decoding success during the evaluation window. Furthermore, an outcome of the evaluation (IS or OOS indication) may be indicated to the higher layer (and/or to the base station) at each interval of time T indication    210 , as shown in  FIG. 2 . Upon reception of N 310  number of consecutive OOS indications, the higher layer starts an RLF timer T 310 . Upon reception of N 311  number of consecutive IS indications, the higher layer stops the T 310  timer. Upon the expiry of the T 310  timer, an RLF procedure is ordered by the higher layer. In some aspects, the thresholds mentioned herein, the time durations (e.g.,  204 ,  206 ,  208 ), the timers T 310  and T 311 , as well as the parameters N 310  and N 311  may be configured dynamically or by higher layers (e.g., via RRC signaling). 
     Three state indications for the RLM procedure for unlicensed spectrum operation (with LBT). 
       FIG. 3  illustrates RLM-RS transmissions and various RLM-related parameters for communications within an unlicensed spectrum where RLM-RS is subject to LBT, in accordance with some aspects. 
     In some aspects associated with unlicensed spectrum operation, the RLM-RS transmissions  302  with periodicity  306  may be subject to LBT. For simplicity, it may be assumed that if LBT fails then RLM-RS is not transmitted for that transmission occasion (e.g., as indicated by reference  304  in  FIG. 3 , where RLM-RS is not transmitted for certain transmission occasions). If LBT succeeds, the RLM-RS is transmitted for that transmission occasion (e.g., as indicated by  302  in  FIG. 3 ). 
     The main issue with respect to RLM is that dropped RLM-RS transmission occasions due to LBT failure may trigger RLF that is undesired. In this case, for an evaluation period (e.g., T Evaluate_out_RS    310  or T Evaluate_in_RS    308 ), a UE determines whether IS or OOS indication can be determined with sufficient confidence and accuracy. For example, if RLM-RS is defined as a synchronization signal (SS)/physical broadcast channel (PBCH) (SS/PBCH) block index, a UE may perform primary synchronization signal (PSS) and/or secondary synchronization signal (SSS) detection to determine successful RLM-RS transmission for a particular transmission occasion. A UE may also perform PBCH detection to determine successful RLM-RS transmission for a particular transmission occasion. If the number of successful PSS/SSS/PBCH detections within an evaluation period is 0 (or smaller than a threshold), then a UE may determine a third indication called Transmission Failure (TXF) indication (implying IS/OOS indication cannot be determined or cannot be determined with sufficient confidence and accuracy). 
     If the number of successful PSS/SSS/PBCH detections within an evaluation period is higher than another threshold (or is 100%), then the UE may proceed with determining IS/OOS indications  312  (e.g., as discussed in connection with  FIG. 2 ). This is feasible because generally, the required SINR for OOS indication is much higher than the required SINR for PSS/SSS/PBCH detection and, therefore, a successful PSS/SSS/PBCH detection may not automatically imply an IS indication. 
     In some aspects, a preamble reference signal (preamble-RS) may be transmitted from the serving gNB indicating an acquired channel occupancy time (COT) length. A UE may use such a detected preamble-RS to assume that certain RLM-RS transmissions are not dropped due to LBT. 
     In summary, several implementation-specific options may be available for a UE to report a choice from three indicators—IS/OOS/TXF to the higher layers and/or to the base station. In some embodiments, T Evaluate_out_RS    310  may be used for evaluation of OOS and TXF, and T Evaluate_in_RS    308  may be used for evaluation of IS and TXF. Alternatively, a separate time interval T Evaluate_TXF_RS  (not illustrated in  FIG. 3 ) may configured and be used for evaluating TXF. In this case, T Evaluate_out_RS  may be used for evaluation of OOS, T Evaluate_in_RS  is used for evaluation of IS, and T Evaluate_TXF_RS  may be used for evaluating TXF. Upon reception of N 312  number of consecutive TXF indications, the higher layer may start an RLF timer T 310 . Upon reception of N 311  number of consecutive IS indications (without any TXF indication), or N 311 +Δ number of consecutive IS-indications (in case there are δ number of TXF indications received in between, where Δ and δ can be pre-configured or configured by higher layer depending on load condition etc.), or a combinations thereof, the higher layer stops the T 310  timer. Upon expiry of T 310  timer, an RLF procedure is ordered by the higher layer. In some aspects, the thresholds mentioned herein, the time period durations (e.g.,  306 ,  308 ,  310 ), the timers T 310  and T 311 , as well as the parameters N 310 , N 311 , Δ, and δ may be configured dynamically or by higher layers (e.g., via RRC signaling). 
     UE reporting for RLM procedure during unlicensed spectrum operation (with LBT). 
     The capability of a UE to determine TXF with reasonable accuracy may be used for distinguishing poor link quality (OOS) from transmission failure (due to LBT) in certain cases and can be beneficial to limit false RLF triggers by the UE. In order to test this LIE capability, a reporting mechanism may be beneficial. A report can also be beneficial for the gNB to judge the accuracy of TXF prediction by a UE in a certain environment (since a gNB is aware of the dropped RLM-RS transmission occasions). For example, based on the report, a gNB can set or adjust the UE specific RLM parameters appropriately. 
       FIG. 4  illustrates UE reporting options of a detected transmission failure (TXF) occasions of RLM-RS, in accordance with some aspects. As an example, a UE may report on TXF determination for a certain T Evaluate_TXF_RS  measurement duration. Assuming three transmission occasions (TO 1 , TO 2 , and TO 3 ) of RLM-RS within a measurement duration T Evaluate_TXF_RS , a UE may generate reports  402 ,  404 , and  406  for multiple measurement durations with reporting information such as TXF, no-TXF, reference signal received power (RSRP), or BLER for the corresponding transmission occasions. 
       FIG. 5  illustrates a signal-to-interference-plus-noise ratio (SINR) range where detection of TXF is beneficial in order to not trigger falls radio link failure (RLF), in accordance with some aspects. Referring to  FIG. 5 , diagram  500  illustrates SINR ranges  502 ,  504 ,  506 , and  508 . SINR range  502  can be associated with observed SINR from zero to SINR threshold  510 . In SINR range  502 , both TXF and OOS indicators can be true. 
     SINR range  504  can be associated with observed SINR from SINR threshold  510  to SINR threshold  512 . In SINR range  504 , the TXF indicator is false and the OOS indicator is true. 
     SINR range  506  can be associated with observed SINR from SINR threshold  512  to SINR threshold  514 . In SINR range  506 , the TXF indicator is false and the OOS indicator is false. 
     SINR range  508  can be associated with observed SINR above the SINR threshold  514 . In SINR range  508 , the TXF indicator is false and the IS indicator is true. 
       FIG. 6  illustrates a block diagram of a communication device such as an evolved Node-B (eNB), a next generation Node-B (gNB), an access point (AP), a wireless station (STA), a mobile station (MS), or a user equipment (UE), in accordance with some aspects and to perform one or more of the techniques disclosed herein. In alternative aspects, the communication device  600  may operate as a standalone device or may be connected (e.g., networked) to other communication devices. 
     Circuitry (e.g., processing circuitry) is a collection of circuits implemented in tangible entities of the device  600  that include hardware (e.g., simple circuits, gates, logic, etc.). Circuitry membership may be flexible over time. Circuitries include members that may, alone or in combination, perform specified operations when operating. In an example, the hardware of the circuitry may be immutably designed to carry out a specific operation (e.g., hardwired). In an example, the hardware of the circuitry may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) including a machine-readable medium physically modified (e.g., magnetically, electrically, moveable placement of invariant massed particles, etc.) to encode instructions of the specific operation. 
     In connecting the physical components, the underlying electrical properties of a hardware constituent are changed, for example, from an insulator to a conductor or vice versa. The instructions enable embedded hardware (e.g., the execution units or a loading mechanism) to create members of the circuitry in hardware via the variable connections to carry out portions of the specific operation when in operation. Accordingly, in an example, the machine-readable medium elements are part of the circuitry or are communicatively coupled to the other components of the circuitry when the device is operating. For example, any of the physical components may be used in more than one member of more than one circuitry. For example, under operation, execution units may be used in a first circuit of a first circuitry at one point in time and reused by a second circuit in the first circuitry, or by a third circuit in a second circuitry at a different time. Additional examples of these components with respect to the device  600  follow. 
     In some aspects, the device  600  may operate as a standalone device or may be connected (e.g., networked) to other devices. In a networked deployment, the communication device  600  may operate in the capacity of a server communication device, a client communication device, or both in server-client network environments. In an example, the communication device  600  may act as a peer communication device in peer-to-peer (P2P) (or other distributed) network environment. The communication device  600  may be a eNB, PC, a tablet PC, a STB, a PDA, a mobile telephone, a smartphone, a web appliance, a network router, switch or bridge, or any communication device capable of executing instructions (sequential or otherwise) that specify actions to be taken by that communication device. Further, while only a single communication device is illustrated, the term “communication device” shall also be taken to include any collection of communication devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), and other computer cluster configurations. 
     Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. For example, the software may reside on a communication device-readable medium. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations. 
     Accordingly, the term “module” is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein. Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using the software, the general-purpose hardware processor may be configured as respective different modules at different times. The software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time. 
     Communication device (e.g., UE)  600  may include a hardware processor  602  (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory  604 , a static memory  606 , and mass storage  607  (e.g., hard drive, tape drive, flash storage, or other block or storage devices), some or all of which may communicate with each other via an interlink (e.g., bus)  608 . 
     The communication device  600  may further include a display device  610 , an alphanumeric input device  612  (e.g., a keyboard), and a user interface (UI) navigation device  614  (e.g., a mouse). In an example, the display device  610 , input device  612  and UI navigation device  614  may be a touchscreen display. The communication device  600  may additionally include a signal generation device  618  (e.g., a speaker), a network interface device  620 , and one or more sensors  621 , such as a global positioning system (GPS) sensor, compass, accelerometer, or another sensor. The communication device  600  may include an output controller  628 , such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NEC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.). 
     The storage device  607  may include a communication device-readable medium  622 , on which is stored one or more sets of data structures or instructions  624  (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. In some aspects, registers of the processor  602 , the main memory  604 , the static memory  606 , and/or the mass storage  607  may be, or include (completely or at least partially), the device-readable medium  622 , on which is stored the one or more sets of data structures or instructions  624 , embodying or utilized by any one or more of the techniques or functions described herein. In an example, one or any combination of the hardware processor  602 , the main memory  604 , the static memory  606 , or the mass storage  616  may constitute the device-readable medium  622 . 
     As used herein, the term “device-readable medium” is interchangeable with “computer-readable medium” or “machine-readable medium”. While the communication device-readable medium  622  is illustrated as a single medium, the term “communication device-readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions  624 . The term “communication device-readable medium” is inclusive of the terms “machine-readable medium” or “computer-readable medium”, and may include any medium that is capable of storing, encoding, or carrying instructions (e.g., instructions  624 ) for execution by the communication device  600  and that cause the communication device  600  to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting communication device-readable medium examples may include solid-state memories and optical and magnetic media. Specific examples of communication device-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples, communication device-readable media may include non-transitory communication device-readable media. In some examples, communication device-readable media may include communication device-readable media that is not a transitory propagating signal. 
     The instructions  624  may further be transmitted or received over a communications network  626  using a transmission medium via the network interface device  620  utilizing any one of a number of transfer protocols. In an example, the network interface device  620  may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network  626 . In an example, the network interface device  620  may include a plurality of antennas to wirelessly communicate using at least one of single-input-multiple-output (SIMO), MIMO, or multiple-input-single-output (MISO) techniques. In some examples, the network interface device  620  may wirelessly communicate using Multiple User MIMO techniques. 
     The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the communication device  600 , and includes digital or analog communications signals or another intangible medium to facilitate communication of such software. In this regard, a transmission medium in the context of this disclosure is a device-readable medium. 
     Although an aspect has been described with reference to specific exemplary aspects, it will be evident that various modifications and changes may be made to these aspects without departing from the broader scope of the present disclosure. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various aspects is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

Metadata:
Filing Date: 20191029
Publication Date: 20221018
Grant Date: 20221018
Priority Date: 20181102
Inventors: MONDAL, BISHWARUP
KUNDU, LOPAMUDRA
LIM, SEAU S.
LEE, DAE WON
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L1/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W56/001", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04J11/0069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W74/0816", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0048", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0051", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/19", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L1/203", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04J11/0069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0051", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W74/0816", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 70462349