Method for classifying neighboring cells in a radio link failure (RLF) report

Abstract

The invention name of the present disclosure is "Method for Classifying Neighboring Cells in Radio Link Failure (RLF) Reports". Embodiments include methods performed by a UE for reporting RLF in cells of a wireless network. Such methods include performing measurements on a plurality of cells, which may include a serving cell and a plurality of neighboring cells. The measurements on each cell are based on one or more types of RS transmitted in that particular cell and include one or more measurement quantities. Such methods include determining that RLF has occurred in the serving cell and classifying the neighboring cell measurements into one or more measurement lists based on one or more classification criteria, which may be related to the type of RS on which the measurements of the corresponding neighboring cell are based and / or the measurement quantities available for the measurements of the corresponding neighboring cell. Such methods include transmitting an RLF report including the one or more measurement lists to a network node.

Description

Technical Field

[0001] The present invention generally relates to wireless communication networks, and more particularly to improvements in mobility aspects when a user equipment (UE) encounters a radio link failure (RLF) in the current serving cell in such networks. Background Art

[0002] Currently, the fifth generation (“5G”) of cellular systems, also known as New Radio (NR), is being standardized within the Third Generation Partnership Project (3GPP). NR is being developed for maximum flexibility to support multiple and substantially different use cases. In addition to typical mobile broadband use cases, there are also machine type communication (MTC), ultra-low latency critical communication (URLLC), sidelink device-to-device (D2D), and several other use cases. The present disclosure generally relates to NR and the previous generation Long Term Evolution (LTE) technology, which is described immediately below.

[0003] Long Term Evolution (LTE) is an umbrella term for a so-called fourth generation (4G) radio access technology developed within the Third Generation Partnership Project (3GPP) and initially standardized in Release 8 (Rel-8) and Release 9 (Rel-9) (also known as Evolved UTRAN (E-UTRAN)). LTE targets various licensed frequency bands and, along with improvements to non-radio aspects, commonly referred to as System Architecture Evolution (SAE), including the Evolved Packet Core (EPC) network. LTE continues to evolve through subsequent releases, which are developed in accordance with the standard-setting process of 3GPP and its working groups (WG), including the Radio Access Network (RAN) WG and sub-working groups (e.g., RAN1, RAN2, etc.).

[0004] LTE Rel-10 supports bandwidths greater than 20 MHz. An important requirement for Rel-10 is backward compatibility with LTE Rel-8. This also includes spectrum compatibility, where a broadband LTE Rel-10 carrier (e.g., greater than 20 MHz) should appear as multiple carriers to LTE Rel-8 (“legacy”) terminals (“user equipment” or UE). Each such carrier can be referred to as a component carrier (CC). For efficient utilization, legacy terminals can be scheduled in all parts of the broadband LTE Rel-10 carrier. This can be done through carrier aggregation (CA), where Rel-10 terminals receive multiple CCs, each having the same structure as a Rel-8 carrier. LTE Rel-12 introduced dual connectivity (DC), enabling a UE to be connected to two network nodes simultaneously, thereby improving connection robustness and / or capacity.

[0005] Figure 1Figure 0 shows an overall exemplary architecture of a network including LTE and SAE. The E-UTRAN 100 includes one or more evolved Node Bs (eNBs) (such as eNBs 105, 110, and 115) and one or more user equipments (UEs) (such as UE 120). As used within the 3GPP standards, a "user equipment" or "UE" denotes any wireless communication device (e.g., a smart phone or a computing device) capable of communicating with network devices compliant with the 3GPP standards, including the E-UTRAN as well as the UTRAN and / or GERAN, as is commonly known for third-generation ("3G") and second-generation ("2G") 3GPP RANs.

[0006] As specified by 3GPP, the E-UTRAN 100 is responsible for all radio-related functions in the network, including radio bearer control, radio access control, radio mobility control, scheduling, and dynamic resource allocation to the UE (such as UE 120) in the uplink and downlink, as well as the security of the communication with the UE. These functions reside in the eNBs (such as eNBs 105, 110, and 115). Each of the eNBs is capable of serving a geographical coverage area including one or more cells (such as cells 106, 111, and 116 served by eNBs 105, 110, and 115, respectively).

[0007] The eNBs in the E-UTRAN communicate with each other via the X1 interface, as Figure 1 shown. The eNBs are also responsible for the E-UTRAN interface to the EPC 130, specifically the S1 interface to the Mobility Management Entity (MME) and the Serving Gateway (SGW) ( Figure 1 collectively shown as MME / S-GW 134 and 138 in Figure 0). Generally, the MME / S-GW handles the overall control of the UE and the data flow between the UE and the rest of the EPC. More specifically, the MME processes the signaling (e.g., control plane) protocol between the UE and the EPC, which is referred to as the non-access stratum (NAS) protocol. The SGW handles all Internet Protocol (IP) data packets (e.g., data or user plane) between the UE and the EPC and serves as the local mobility anchor for the data bearer when the UE 120 moves between eNBs (such as eNBs 105, 110, and 115).

[0008] The EPC 130 may also include a Home Subscriber Server (HSS) 131, which manages user and subscriber-related information. The HSS 131 may also provide support functions in mobile management, call and session establishment, user authentication, and access authorization. The functions of the HSS 131 may be related to the functions or operations of a traditional Home Location Register (HLR) and Authentication Center (AuC).

[0009] In some embodiments, the HSS 131 can communicate with a User Data Repository (UDR)— Figure 1 marked as EPC-UDR 135 in the [document]—via the Ud interface. The EPC-UDR 135 can store user credentials after they have been encrypted by the AuC algorithms. These algorithms are not standardized (i.e., vendor-specific), such that the encrypted credentials stored in the EPC-UDR 135 are not accessible to any other vendor except the vendor of the HSS 131.

[0010] Figure 2A Shows a high-level block diagram of a exemplary LTE architecture in terms of its constituent entities—UE, E-UTRAN, and EPC—and the high-level functional partitioning into access stratum (AS) and non-access stratum (NAS). Figure 2A Also shows two specific interface points, namely Uu (UE / E-UTRAN radio interface) and S1 (E-UTRAN / EPC interface), each of which uses a specific set of protocols, namely radio protocols and S1 protocols. Each of the two protocols can be further divided into user plane (or "U plane") and control plane (or "C plane") protocol functionality. On the Uu interface, the U plane carries user information (e.g., data packets), while the C plane carries control information between the UE and the E-UTRAN.

[0011] Figure 2B Shows a block diagram of an exemplary control (C) plane protocol stack between the UE, eNB, and MME. The exemplary protocol stack includes the Physical (PHY), Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC) layers between the UE and the eNB. The PHY layer is concerned with how to use and which characteristics to use for transmitting data over the transport channels on the LTE radio interface. The MAC layer provides data transfer services on the logical channels, maps the logical channels to the PHY transport channels, and reallocates PHY resources to support these services. The RLC layer provides error detection and / or correction, concatenation, segmentation, and reassembly, and reordering of the data transmitted to or from the upper layers. The PDCP layer provides encryption / decryption and integrity protection for both the U plane and the C plane and other functions for the U plane (such as header compression). The exemplary protocol stack also includes non-access stratum (NAS) signaling between the UE and the MME.

[0012] The RRC layer controls the radio interface for communication between the UE and the eNB and the mobility of the UE between cells in the E-UTRAN. After the UE is powered on, it will be in the RRC_IDLE state until an RRC connection to the network is established, at which point the UE will transition to the RRC_CONNECTED state (e.g., where data transmission can occur). After the connection to the network is released, the UE returns to RRC_IDLE. In the RRC_IDLE state, the UE's radio is active on a discontinuous reception (DRX) schedule configured by a higher layer. During a DRX active period (also referred to as the "DRX on-duration"), the RRC_IDLE UE receives system information (SI) broadcast by the serving cell, performs measurements on neighboring cells to support cell reselection, and monitors the paging channel on the PDCCH for paging from the EPC via the eNB. The UE in the RRC_IDLE state is known in the EPC and has an assigned IP address, but is not known to the serving eNB (e.g., there is no stored context).

[0013] Logical channel communication between the UE and the eNB is carried out via radio bearers. Since LTE Rel-8, signaling radio bearers (SRBs) SRB0, SRB1, and SRB2 have been available for transmitting RRC and NAS messages. SRB0 is used for RRC connection establishment, RRC connection resume, and RRC connection re-establishment. Once any of these operations has been successful, SRB1 is used to handle RRC messages (which may include NAS messages piggybacked) and for NAS messages before the establishment of SRB2. SRB2 is used for NAS messages and low-priority RRC messages (e.g., logged measurement information). SRB0 and SRB1 are also used to establish and modify data radio bearers (DRBs) for carrying user data between the UE and the eNB.

[0014] The multiple access scheme of LTE PHY is based on orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) in the downlink and single carrier frequency division multiple access (SC-FDMA) based on a cyclic prefix in the uplink. To support transmissions in paired and unpaired spectrums, LTE PHY supports frequency division duplexing (FDD) (including full-duplex and half-duplex operations) and time division duplexing (TDD). Figure 3 Shows a exemplary radio frame structure ("Type 1") for LTE FDD downlink (DL) operation. The DL radio frame has a fixed duration of 10 ms and is composed of 20 time slots (labeled 0 to 19, each with a fixed duration of 0.5 ms). A 1-ms subframe consists of two consecutive time slots, where subframe i is composed of time slots 2i and 2i + 1. Each exemplary FDD DL time slot is composed of N DL symbOFDM symbols, each of which consists of N sc OFDM subcarriers. The exemplary values of N DL symb for a subcarrier spacing (SCS) of 15 kHz can be 7 (with normal CP) or 6 (with extended length CP). The value of N sc is configurable based on the available channel bandwidth.

[0015] As Figure 3 shown, the combination of a specific subcarrier in a specific symbol is called a resource element (RE). Each RE is used to transmit a specific number of bits, depending on the type of modulation and / or bit mapping constellation used for that RE. For example, some REs may use QPSK modulation to carry two bits, while other REs may use 16 or 64-QAM to carry four or six bits respectively. The radio resources of LTE PHY are also defined in terms of physical resource blocks (PRBs). A PRB spans N DL symb symbols within the duration of a time slot (i.e., N RB sc symbols) and N RB sc subcarriers, where N

[0016] is typically 12 (for a 15-kHz subcarrier bandwidth) or 24 (for a 7.5-kHz bandwidth). Figure 3 The exemplary LTE FDD uplink (UL) radio frame can be arranged in a manner similar to the exemplary FDD DL radio frame shown in UL symb Using the terms described for the DL above, each UL time slot consists of N sc OFDM symbols, each of which consists of N

[0017] OFDM subcarriers. Generally speaking, an LTE physical channel corresponds to a set of REs carrying information from higher layers. The downlink (i.e., eNB to UE) physical channels provided by LTE PHY include the Physical Downlink Shared Channel (PDSCH), Physical Multicast Channel (PMCH), Physical Downlink Control Channel (PDCCH), Relay Physical Downlink Control Channel (R-PDCCH), Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), and Physical Hybrid ARQ Indicator Channel (PHICH). Additionally, the LTE PHY downlink includes various reference signals (such as the Channel State Information Reference Signal CSI-RS), synchronization signals, and discovery signals.

[0018] The PDSCH is the main physical channel for unicast downlink data transmission and also for the transmission of RAR (Random Access Response), certain system information blocks, and paging information. The PBCH carries the basic system information required for the UE to access the network. The PDCCH is used to transmit downlink control information (DCI), including scheduling information for DL messages on the PDSCH, grants for UL transmissions on the PUSCH, and channel quality feedback for UL channels (e.g., CSI). The PHICH carries HARQ feedback (e.g., ACK / NAK) for UL transmissions made by the UE.

[0019] The uplink (i.e., UE to eNB) physical channels provided by the LTE PHY include the Physical Uplink Shared Channel (PUSCH), the Physical Uplink Control Channel (PUCCH), and the Physical Random Access Channel (PRACH). Additionally, the LTE PHY uplink includes various reference signals, including: Demodulation Reference Signals (DM-RS), which are transmitted to assist the eNB in receiving the associated PUCCH or PUSCH; and Sounding Reference Signals (SRS), which are not associated with any uplink channel.

[0020] The PUSCH is the uplink counterpart of the PDSCH. The PUCCH is used by the UE to transmit uplink control information (UCI), including HARQ feedback for eNB DL transmissions, channel quality feedback for DL channels (e.g., CSI), Scheduling Requests (SR), etc. The PRACH is used for random access preamble transmission.

[0021] Within LTE DL, certain UEs within each LTE subframe are reserved for transmitting reference signals such as the aforementioned DM-RS. Other DL reference signals include Cell-Specific Reference Signals (CRS), Positioning Reference Signals (PRS), and CSI Reference Signals (CSI-RS). UL reference signals include the aforementioned DM-RS and SRS. Other RS-like DL signals include the Primary Synchronization Sequence (PSS) and the Secondary Synchronization Sequence (SSS), which facilitate UE time and frequency synchronization and the acquisition of system parameters (e.g., via the PBCH).

[0022] In LTE, UL and DL data transmissions (e.g., on PUSCH and PDSCH respectively) can be performed with or without explicit permission or assignment of resources by the network (e.g., eNB). Generally, UL transmissions are typically referred to as being "permitted" by the network (i.e., "UL grant"), while DL transmissions are typically referred to as being performed on resources "assigned" (i.e., "DL assignment") by the network. In the case of explicit permission / assignment-based transmissions, Downlink Control Information (DCI) is sent to the UE to inform it about the specific radio resources that will be used for the transmission. In contrast, transmissions without explicit permission / assignment are typically configured to occur at defined periodicities. Given a periodic and / or cyclic UL grant and / or DL assignment, the UE can then initiate data transmission and / or receive data according to a predefined configuration. Such transmissions can be referred to as Semi-Persistent Scheduling (SPS), Configured Grant (CG), or grant-free transmissions.

[0023] Seamless mobility is a key feature of 3GPP radio access technologies (RAT). Generally, the network configures the UE to perform and report Radio Resource Management (RRM) measurements to assist the network in controlling mobility decisions, such as for handovers from a serving cell to an adjacent cell. Seamless handovers ensure that the UE can move back and forth between the coverage areas of different cells without causing excessive interruptions in data transmission. However, there will be situations where the network is unable to switch the UE to the "correct" adjacent cell in a timely manner, which can cause the UE to declare a Radio Link Failure (RLF) or a Handover Failure (HOF).

[0024] The RLF reporting procedure was introduced in LTE Rel-9 as part of Mobility Robustness Optimization (MRO). In this procedure, the UE records relevant information at the time of RLF and later reports this information to the network via the target cell to which the UE is finally connected (e.g., after re-establishment). The reported information can include RRM measurements of various adjacent cells before the mobility operation (e.g., handover). Even so, it is still not defined how the UE classifies, ranks, and / or prioritizes such adjacent cell measurements in the report. This can lead to ambiguity, uncertainty, and / or confusion in terms of how the network interprets such measurements in the UE RLF report. SUMMARY OF THE INVENTION

[0025] Embodiments of the present disclosure provide specific improvements for the handling of RLF by a UE in a wireless network, such as by facilitating solutions to the exemplary problems outlined above and described in more detail below.

[0026] Embodiments of the present disclosure include methods (e.g., procedures) for reporting radio link failures (RLFs) in cells of a wireless network. These exemplary methods can be performed by a user equipment (UE, such as a wireless device, an MTC device, an NB-IoT device, a modem, etc. or their components) operating in a wireless network (such as E-UTRAN, NG-RAN, etc.) that includes multiple cells.

[0027] These exemplary methods can include performing measurements on multiple cells in the wireless network. The multiple cells can include a serving cell (i.e., for the UE) and multiple neighboring cells. The measurements for each particular cell are based on one or more types of reference signals (RSs) transmitted in that particular cell. For example, the type of RS can include any one of the following: cell-specific RS (CRS), channel state information RS (CSI-RS), and synchronization / PBCH signal block (SSB). Additionally, the measurements performed by the UE on each cell can include one or more measurement quantities. For example, the one or more measurement quantities can include any one of the following: reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-interference plus noise ratio (SINR).

[0028] These exemplary methods can also include determining a radio link failure (RLF) that occurs in the serving cell. These exemplary methods can also include classifying neighboring cell measurements into one or more measurement lists based on one or more classification criteria. The classification criteria can be related to one or more of the following: the type of RS on which the measurements for the corresponding neighboring cell are based; and the measurement quantities available for the corresponding neighboring cell. These exemplary methods can also include transmitting an RLF report to a network node, the RLF report including the one or more measurement lists (e.g., as classified).

[0029] In some embodiments, the classification criteria can include a particular measurement quantity (e.g., RSRP, RSRQ, or SINR). In such embodiments, the classification operation can include sorting the neighboring cell measurements into the one or more measurement lists based on the value of the particular measurement quantity measured for the corresponding neighboring cell.

[0030] In some embodiments of these embodiments, the classification criteria can include multiple measurement quantities, and the one or more measurement lists can include multiple measurement lists associated with the corresponding measurement quantities. In such embodiments, the neighboring cell measurements including the corresponding measurement quantity can be sorted into the corresponding measurement list.

[0031] In other embodiments of these embodiments, the classification criterion can further include a specific RS type. In such embodiments, sorting the neighboring cell measurements into the one or more measurement lists can be based on the value of a specific measurement quantity measured for the corresponding neighboring cell according to the specific RS type. For example, when the value of the specific measurement quantity is equal for two neighboring cells of the neighboring cell, sorting the measurements of the two neighboring cells can be based on the value of one of the following measured for the two neighboring cells:

[0032] · Another measurement quantity based on the specific RS type; or

[0033] · A specific measurement quantity based on another RS type.

[0034] In other embodiments of these embodiments, the classification criterion can further include a plurality of RS types, and the one or more measurement lists can include a plurality of measurement lists associated with the corresponding plurality of RS types. In such embodiments, sorting the neighboring cell measurements into the one or more measurement lists can be based on the value of a specific measurement quantity measured for the corresponding neighboring cell according to the corresponding RS type.

[0035] In some embodiments, neighboring cell measurements can be performed on multiple carrier frequencies. In some embodiments of these embodiments, the one or more measurement lists include a plurality of measurement lists associated with the corresponding plurality of carrier frequencies, and the neighboring cell measurements made at the corresponding carrier frequencies are sorted into the corresponding measurement lists.

[0036] In other embodiments of these embodiments, the one or more measurement lists are associated with the plurality of carrier frequencies such that the neighboring cell measurements made at all carrier frequencies of the carrier frequencies are sorted into the one or more measurement lists. In some embodiments of these embodiments, the one or more measurement lists include a plurality of measurement lists associated with the corresponding plurality of RS types and with all carrier frequencies of the carrier frequencies. In such embodiments, the neighboring cell measurements made at the corresponding RS types are sorted into the corresponding measurement lists.

[0037] In some embodiments, the one or more measurement lists can include a plurality of measurement lists. In such embodiments, the classification operation can include combining the plurality of measurement lists into a single measurement list, the combination being in the priority order of one or more of the following associated with the corresponding measurement lists: carrier frequency, RS type, and measurement quantity. In such embodiments, the RLF report can include the single measurement list.

[0038] In various embodiments, the one or more measurement lists (e.g., included in the RLF report) can include one of the following types of measurement values:

[0039] · The value of a specific measurement quantity used as a classification criterion, which is based on a specific RS type that also serves as a classification criterion;

[0040] · The value of a specific measurement quantity used as a classification criterion, which is based on any one of the RS types;

[0041] · The value of any available measurement quantity, which is based on a specific RS type used as a classification criterion; or

[0042] · The value of any available measurement quantity, which is based on any one of the RS types.

[0043] Other embodiments include a user equipment (UE, such as a wireless device, an MTC device, an NB-IoT device, or components thereof, such as a modem), which is configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments include a non-transitory computer-readable medium storing program instructions that, when executed by a processing circuit, configure such a UE to perform operations corresponding to the exemplary methods described herein.

[0044] These and other objects, features, advantages, and benefits of the embodiments of the present disclosure will become apparent when reading the following "Detailed Description" in view of the accompanying drawings briefly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a high-level block diagram of an exemplary architecture of a Long Term Evolution (LTE) evolved UTRAN (E-UTRAN) and an evolved packet core (EPC) network standardized by 3GPP.

[0046] Figure 2A is a high-level block diagram of an exemplary E-UTRAN architecture in terms of its constituent components, protocols, and interfaces.

[0047] Figure 2B is a block diagram of exemplary protocol layers of the control plane part of the radio (Uu) interface between a user equipment (UE) and the E-UTRAN.

[0048] Figure 3 is a block diagram of an exemplary downlink LTE radio frame structure for frequency division duplex (FDD) operation.

[0049] Figure 4 is a high-level timing diagram showing two stages of an exemplary radio link failure (RLF) in LTE and NR according to various exemplary embodiments of the present disclosure.

[0050] Figure 5 shows a more detailed version of the operation of a UE during an exemplary LTE RLF process.

[0051] Figure 6 Shows a exemplary ASN.1 data structure defining the Radio Resource Control (RRC) RLF-TimersAndConstants information element (IE).

[0052] Figure 7 Shows a exemplary arrangement for estimating the Physical Downlink Control Channel (PDCCH) quality based on UE Radio Link Monitoring (RLM) measurements.

[0053] Figure 8 Shows certain operations of a exemplary Long Term Evolution (LTE) Random Access (RA) procedure initiated by a UE.

[0054] Fig. 9 Shows a exemplary ASN.1 data structure of the RRC RACH-ConfigCommon IE.

[0055] Fig.10 Shows a exemplary ASN.1 data structure of the UEInformationRequest message.

[0056] Figure 11 includes Fig.11A - C, showing a exemplary ASN.1 data structure of the UEInformationResponse message.

[0057] Figure 12-13 Shows a flowchart of a exemplary method (e.g., process) for classifying neighboring cell measurements into a list according to various exemplary embodiments of the present disclosure.

[0058] Fig.14 Shows a flowchart of a exemplary method (e.g., process) of a User Equipment (UE, such as a wireless device, an MTC device, an NB-IoT device, etc. or their components) according to various exemplary embodiments of the present disclosure.

[0059] Fig.15 Shows a high-level view of a exemplary 5G network architecture.

[0060] Fig.16 Shows a block diagram of a exemplary wireless device or UE according to various exemplary embodiments of the present disclosure.

[0061] Fig.17 Shows a block diagram of a exemplary network node according to various exemplary embodiments of the present disclosure.

[0062] Fig.18 Shows a block diagram of a exemplary network configured to provide an over-the-top (OTT) data service between a host computer and a UE according to various exemplary embodiments of the present disclosure. Detailed Description

[0063] The embodiments outlined above will now be described more fully with reference to the accompanying drawings. However, other embodiments are included within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be construed as being limited only to the embodiments presented herein; rather, these embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0064] In general, all terms used herein will be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is explicitly given and / or implied by the context in which it is used. All references to an / a / the element, apparatus, component, part, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, part, step, etc., unless otherwise explicitly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless a step is explicitly described as being after or before another step and / or where it is implied that a step must be after or before another step. Any feature of any embodiment of the embodiments disclosed herein may be applied to any other embodiment where appropriate. Similarly, any advantage of any embodiment of the embodiments may be applied to any other embodiment, and vice versa. By the following description, other objects, features, and advantages of the included embodiments will be apparent.

[0065] Furthermore, the following terms are used throughout the description given below:

[0066] · Radio node: As used herein, a "radio node" can be a "radio access node" or a "wireless device".

[0067] · Radio access node: As used herein, a "radio access node" (or equivalent "radio network node", "radio access network node", or "RAN node") can be any node operating in a radio access network (RAN) of a cellular communication network to wirelessly transmit and / or receive signals. Some examples of radio access nodes include, but are not limited to, base stations (e.g., a new radio (NR) base station (gNB) in a 3GPP fifth generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP LTE network), base station distributed components (e.g., CU and DU), high-power or macro base stations, low-power base stations (e.g., micro, pico, femto, or home base stations or the like), integrated access backhaul (IAB) nodes, transmission points, remote radio units (RRU or RRH), and relay nodes.

[0068] · Core network node: As used herein, a "core network node" is any type of node in a core network. Some examples of core network nodes include, for example, a Mobility Management Entity (MME), a Serving Gateway (SGW), a Packet Data Network Gateway (P-GW), an Access and Mobility Management Function (AMF), a Session Management Function (SMF), a Location Management Function (LMF), a User Plane Function (UPF), a Network Exposure Function (NEF), or the like.

[0069] · Wireless device: As used herein, a "wireless device" (or simply "WD") is any type of device that has the right to access a cellular communication network (i.e., is served by it) by wirelessly communicating with network nodes and / or other wireless devices. Wireless communication can involve using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information over the air to transmit and / or receive wireless signals. Some examples of wireless devices include, but are not limited to, smart phones, mobile phones, cellular phones, Voice over Internet Protocol (VoIP) phones, wireless local loop phones, desktop computers, Personal Digital Assistants (PDAs), wireless photographic devices, gaming consoles or devices, music storage devices, playback devices, wearable devices, wireless endpoints, mobile stations, tablets, laptops, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart devices, wireless Customer Premises Equipment (CPE), Machine-Type Communication (MTC) devices, Internet of Things (IoT) devices, in-vehicle wireless terminal devices, etc. Unless otherwise stated, the term "wireless device" is used interchangeably with "User Equipment" (or simply "UE") herein.

[0070] · Network node: As used herein, a "network node" is any node that is part of a radio access network (e.g., the above-mentioned "radio access node" or equivalent name) or part of a core network (e.g., the above-mentioned core network node). Functionally, a network node is a device that is capable of, configured to, arranged to, and / or operable to communicate directly or indirectly with wireless devices and / or with other network nodes or devices in a cellular communication network to enable and / or provide wireless access to wireless devices and / or perform other functions (e.g., management) in a cellular communication network.

[0071] Note that the description herein focuses on 3GPP cellular communication systems and thus generally uses 3GPP terms or terms similar to 3GPP terms. However, the concepts disclosed herein are not limited to 3GPP systems. Additionally, although the term "cell" is used herein, it should be understood that (especially for 5G NR) beams can be used instead of cells, and thus the concepts described herein apply equally to cells and beams.

[0072] As outlined above, during a current Radio Link Failure (RLF) procedure, the UE records relevant information at the time of the RLF and later reports such information to the network via the target cell to which the UE is finally connected (e.g., after re - establishment). The reported information can include Radio Resource Management (RRM) measurements of various neighboring cells before a mobility operation (e.g., handover). Even so, it is not defined how the UE classifies, ranks, and / or prioritizes such neighboring cell measurements in the report. This can lead to ambiguity, uncertainty, and / or confusion in terms of how the network interprets such measurements in the UE RLF report, which is discussed in more detail below.

[0073] As described above, prior to LTE Rel - 13, only two RRC states were defined for the UE: RRC_IDLE and RRC_CONNECTED. In LTE Rel - 13, a mechanism was introduced to allow the UE to be suspended by the network in a suspended state similar to RRC_IDLE, but with some important differences. First, the suspended state is not a third RRC "state" alongside RRC_IDLE and RRC_CONNECTED; rather, it can be considered a "sub - state" of RRC_IDLE. Second, both the UE and the serving eNB store the UE's AS (e.g., S1 - AP) context and RRC context after suspension. Later when the suspended UE needs to resume the connection (e.g., to send UL data), instead of going through the regular service request procedure, the suspended UE simply sends an RRCConnectionResume - Request message to the eNB. The eNB resumes the S1AP context and responds with an RRCConnectionResume message. There is no elaborate exchange of the security context between the MME and the eNB, nor is there an establishment of the AS security context. The saved AS and RRC contexts are only resumed from the location where they were previously suspended. Reducing signaling can reduce UE latency (e.g., for a smartphone accessing the Internet) and UE signaling. This can lead to reduced UE energy consumption, especially for machine - type communication (MTC) devices that send very little data, such that signaling is the main consumer of energy.

[0074] In 3GPP, the research project on the new air interface for 5G has recently been completed, and 3GPP is now continuing to work on standardizing this new air interface, commonly abbreviated as NR (New Radio). While LTE was mainly designed for user - to - user communication, 5G / NR networks are envisioned to support high single - user data rates (e.g., 1 Gb / s) as well as massive machine - to - machine communication involving short burst transmissions from many different devices sharing a frequency bandwidth.

[0075] Similar to LTE, NR uses CP-OFDM (Cyclic Prefix Orthogonal Frequency Division Multiplexing) in the downlink and CP-OFDM and DFT-s-OFDM (DFT-Spread OFDM) in the uplink. In the time domain, NR downlink and uplink physical resources are organized into equal-sized subframes of 1 ms each. The subframes are further divided into multiple time slots of equal duration, where each time slot includes multiple OFDM-based symbols.

[0076] In NR, the RRC state includes the RRC_INACTIVE state, which has properties similar to the suspended substate in LTE Rel-13. However, the RRC_INACTIVE state has slightly different properties as it is an independent RRC state rather than part of RRC_IDLE as in LTE. Additionally, the CN / RAN connection (NG or N2 interface) is kept active during RRC_INACTIVE, while it is suspended in LTE.

[0077] In the RRC_CONNECTED state, the network generally configures the UE to perform and report RRM measurements to assist the network in controlling mobility decisions such as handovers from one cell to another. When something unexpected occurs in any of the mobility-related processes including handovers, the RLF process is typically triggered in the UE. The RLF process involves interactions between RRC and lower-layer protocols such as PHY (or L1), MAC, RLC, etc., including radio link monitoring (RLM) on L1.

[0078] In case of handover failure (HOF) and RLF, the UE can take autonomous actions such as attempting to select a cell and initiating a re-establishment process so that the UE can remain reachable by the network. Generally, the UE declares RLF only when it realizes that there is no reliable communication channel (or radio link) available between itself and the network. Additionally, re-establishing the connection requires signaling with the newly selected cell (e.g., random access procedure, exchanging various RRC messages, etc.), thus introducing latency until the UE can again reliably transmit and / or receive user data with the network.

[0079] According to 3GPP TS 36.331 (v15.7.0), the possible causes of RLF include:

[0080] 1) Expiry of the radio link monitoring (RLM)-related timer T310;

[0081] 2) Expiry of the timer T312 associated with the measurement report (no handover command is received from the network within the duration of this timer, although measurement reports are sent while T310 is running);

[0082] 3) When the maximum number of RLC retransmissions is reached; and

[0083] 4) When receiving a random access problem indication from the MAC entity.

[0084] Due to RLF causing re - establishment in a new cell and degradation of UE / network performance and end - user experience, it is in the network's interest to understand the reasons for UE RLF and optimize mobility - related parameters (such as the triggering conditions for measurement reports) to reduce, minimize, and / or avoid subsequent RLF. Before Rel - 9 Mobile Robustness Optimization (MRO), only the UE knew the radio quality at the time of RLF, the actual reasons for declaring RLF, etc. To identify the RLF reasons, the network requires more information from the UE and from neighboring base stations (such as eNBs).

[0085] As described above, various events and / or problems can trigger RLF in LTE and NR. However, for the purposes of this disclosure, the two most important aspects are: 1) RLF caused by radio link or PHY problems (such as the expiration of timer T310); and 2) RLF caused by random access problems as indicated by the MAC layer. Although RLF can be triggered by other reasons (such as RLC), the discussion of these aspects is omitted for the sake of brevity and / or simplicity.

[0086] The principles of RLM are similar in LTE and NR. Generally, the UE monitors the link quality of the UE's serving cell and uses that information to determine whether the UE is in - sync (IS) or out - of - sync (OOS) with that serving cell. In LTE, RLM is performed by the UE measuring the downlink reference signal (such as CRS) in the RRC_CONNECTED state. If RLM (i.e., by L1 / PHY) indicates to the UE RRC layer the number of consecutive OOS conditions, the RRC starts the radio link failure (RLF) process and declares RLF after the expiration of a timer (such as T310). The L1 RLM process is performed by actually comparing the estimated CRS measurements with certain target block error rates (BLERs) called Qout and Qin. In particular, Qout and Qin correspond to the BLER for the assumed PDCCH / PCIFCH transmissions from the serving cell, with exemplary values of 10% and 2% respectively. In NR, the network can define the RS type (such as CSI - RS and / or SSB), the exact resources to be monitored, and even the BLER targets for IS and OOS indications.

[0087] Figure 4It is a high-level timing diagram showing two stages of the RLF process in LTE and NR. The first stage starts when a radio problem is detected and causes radio link failure detection after no recovery occurs during period T1. The second stage starts upon RLF detection or handover failure and ends with the UE returning to RRC_IDLE when no recovery occurs during period T2.

[0088] Figure 5 A more detailed version showing the operation of the UE during a demonstration LTE RLF process. In this example, the UE detects N310 consecutive OOS conditions during the L1 RLM process as described above and then initiates timer T310. Subsequent operations are performed by a higher layer (e.g., RRC). After the expiration of T310, the UE starts T311 and RRC reestablishment, searches for the best target cell. After selecting the target cell for reestablishment, the UE obtains the system information (SI) of the target cell and performs random access (e.g., via RACH). The duration from the expiration of T310 until this point can be considered the reestablishment delay of the UE. Finally, the UE obtains access to the target cell and sends an RRC reestablishment request message to the target cell. The duration from the expiration of T310 until this point can be considered the total RRC reestablishment delay.

[0089] These operations are further specified in 3GPP TS 36.331 (v15.7.0), and the relevant part is provided in the following excerpt.

[0090] ***Start of excerpt from 3GPP specification***

[0091] 5.2.2.9 Actions upon receiving SystemInformationBlockType2

[0092] Upon receiving SystemInformationBlockType2, the UE shall:

[0093] 1> Apply the configuration contained in radioResourceConfigCommon; ...

[0094] 1> If in RRC_CONNECTED and the UE is configured with RLF timers and constants, the values received within rlf-TimersAndConstants (ifin RRC_CONNECTED andUE is configured withRLF timers and constants values received within rlf-TimersAndConstants):

[0095] 2> Do not update the values of the constants and timers in ue-TimersAndConstants, except for the value of timer T300; ...

[0096] 5.3.10.0 General

[0097] The UE shall: ...

[0098] 1> If the received radioResourceConfigDedicated includes rlf-TimersAndConstants, then:

[0099] 2> Reconfigure the values of the constants and timers as specified in 5.3.10.7; ...

[0100] 5.3.10.7 Radio Link Failure Timer and Constant Reconfiguration

[0101] The UE shall:

[0102] 1> If the received rlf-TimersAndConstants is set to release, then:

[0103] 2> Use the values of timers T301, T310, T311 and constants N310, N311 included in ue-TimersAndConstants received in SystemInformationBlockType2 (or SystemInformationBlockType2-NB in NB-IoT);

[0104] 1> Otherwise:

[0105] 2> Reconfigure the values of the constants and timers according to the received rlf-TimersAndConstants;

[0106] 1> If the received rlf-TimersAndConstantsSCG is set to release, then:

[0107] 2> Stop timer T313 (if it is running), and

[0108] 2> Release the values of constants n313 and n314 and timer t313;

[0109] 1> Otherwise:

[0110] 2> Reconfigure the values of constants and timers according to the received rlf-TimersAndConstantsSCG; ...

[0111] 5.3.10.11 Dedicated Resource Configuration for SCG

[0112] The UE shall: ...

[0113] 1> If the received radioResourceConfigDedicatedSCG includes rlf-TimersAndConstantsSCG, then:

[0114] 2> Reconfigure the values of constants and timers as specified in 5.3.10.7; ...

[0115] 5.3.11.1 Detection of Physical Layer Problems in RRC_CONNECTED

[0116] The UE shall:

[0117] 1> When receiving N310 consecutive "OOS" indications for the PCell from the lower layer while T300, T301, T304, and T311 are not running:

[0118] 2> Start timer T310;

[0119] 1> When receiving N313 consecutive "OOS" indications for the PSCell from the lower layer while T307 is not running:

[0120] 2> Start T313;

[0121] Note: Physical layer monitoring and related autonomous actions shall not be applied to SCell, except for PSCell.

[0122] 5.3.11.2 Recovery of Physical Layer Problems

[0123] When receiving N311 consecutive "IS" indications for the PCell from the lower layer while T310 is running, the UE shall:

[0124] 1> Stop timer T310;

[0125] 1> Stop timer T312 (if it is running);

[0126] Note 1: In this case, the UE maintains the RRC connection without explicit signaling, i.e., the UE maintains the complete radio resource configuration.

[0127] Note 2: The time period during which neither "IS" nor "OOS" is reported by layer 1 does not affect the evaluation of the number of consecutive "IS" or "OOS" indications.

[0128] When receiving N314 consecutive "IS" indications for the PSCell from a lower layer while T313 is running, the UE shall:

[0129] 1> Stop timer T313;

[0130] ***End of excerpt from 3GPP specification***

[0131] In addition, Figure 6 Figure shows a sample ASN.1 data structure (also taken from 3GPP TS 36.331), defining the RRCRLF-TimersAndConstants information element (IE) that contains UE-specific timers and constants applicable to the UE in the RRC_CONNECTED state. Definitions of some of the fields are provided in the following table. Figure 6 in the following.

[0132]

[0133]

[0134]

[0135]

[0136] When discontinuous reception (DRX) is not configured, OOS occurs when the estimated downlink radio link quality for the last 200 ms period becomes worse than the threshold Qout. Similarly, in the absence of DRX, IS occurs when the estimated downlink radio link quality for the last 100 ms period becomes better than the threshold Qin. When asynchronous is detected, the UE initiates an evaluation of synchronization.

[0137] When DRX is used to reduce UE power consumption, the OOS and IS evaluation periods are extended based on the configured DRX cycle length. Whenever OOS occurs, the UE starts an IS evaluation. Thus, the same period (TEvaluate_Qout_DRX) is used for evaluating OOS and IS. However, from the start of the RLF timer (T310) until its expiration, the IS evaluation period is shortened to 100 ms, which is the same as in the case without DRX. If the timer T310 is stopped due to N311 consecutive IS indications, the UE performs the IS evaluation according to the DRX-based period (TEvaluate_Qout_DRX).

[0138] In summary, the LTE RLM process is based on measuring the cell-specific reference signal (CRS) to "estimate" the PDCCH quality, which relies on the UE being in the RRC_CONNECTED state in the LTE serving cell that transmits the PDCCH and CRS. The CRS is associated with a specific physical cell identifier (PCI). Additionally, LTE RLM has been specified such that the network does not need to configure any parameters, and the UE internally generates IS / OOS events for detecting radio link problems. On the other hand, the RLF process (including SCG failures) is controlled by the RRC and configured by the network via counters N310, N311, N313, N314 (which act as filters to avoid premature RLF triggering) and timers T310, T311, T313, and T314.

[0139] The mapping between CRS-based RLM measurements and the assumed PDCCH BLER is retained as being dependent on the UE implementation. However, the performance is verified through conformance tests defined for various environments. Additionally, the downlink quality is calculated based on the RSRP of the CRS over the entire frequency band because the UE does not necessarily know where the PDCCH will be scheduled. This is shown in Figure 7 it.

[0140] In LTE, RLF can also be triggered by problems in the random access (RA) process that occurs at the MAC layer (e.g., as defined in 3GPP TS 36.321). Random access in LTE can be configured as contention-based random access (CBRA) with an inherent risk of collisions or contention-free RACH (CFRA), where dedicated RA resources are reserved / assigned by the network for a specific UE at a specific time. For example, the network can configure CFRA during the handover of a UE.

[0141] Figure 8 Steps (i.e., operations) in a demonstration LTE CBRA process are shown. In step 1, the UE randomly selects an access preamble from a known set of preambles transmitted by the network over the broadcast channel. The aim is to avoid collisions by separating the preambles in the code domain. In LTE, there are typically 64 different available preambles in each cell. These can be divided into multiple preamble groups, which allows the UE to use one bit to signal whether it requires radio resources for small or large messages (data encapsulation). That is, a preamble randomly selected from one group can indicate that the UE has a small amount of data to transmit, while a preamble randomly selected from another group indicates a need for resources for a larger amount of data.

[0142] The UE transmits the RA preamble only on certain UL time / frequency resources, making the resources known to all UEs via broadcast system information (SI). The eNB detects all non-conflicting preambles transmitted by the UEs in these resources and estimates the round-trip time (RTT) for each UE. In an LTE OFDM-based system, the RTT is required to achieve time and frequency synchronization of the UE in DL and UL.

[0143] In step 2, the RA response (RAR) from the eNB to the UE carries the RTT, a temporary UE identifier (e.g., temporary cell RNTI, TC-RNTI), and the UL resources to be used in step 3. As described above, the UE can use the received RTT to adjust its transmission window to obtain UL synchronization. The RAR is scheduled on the DL shared channel (e.g., PDSCH) and indicated on the DL control channel (e.g., PDCCH) using the identifier reserved for the RAR. All UEs that have transmitted the RA preamble monitor the DL control channel for the RAR within a time window after their preamble transmission. If the UE does not detect the RAR within the time window, it declares a failed attempt and repeats step 1 with increased transmission power.

[0144] The received UL resource assignment to be used in step 3 is basically a pointer (e.g., pointing to a location on the UL time / frequency resource grid), which accurately notifies the UE about in which subframes (time) to transmit and which resource blocks (frequency) to use. The higher layer indicates a 20-bit UL grant to the PHY, as defined in 3GPP TS 36.321 and 36.213. In LTE PHY, this is called the RAR grant and is carried on the PDCCH by downlink control information (DCI) in a specific format. The RAR grant size aims to strike a balance between minimizing the number of bits to convey the resource assignment while providing some resource assignment flexibility to the eNB scheduler. Generally, the length of the PHY message depends on the system bandwidth.

[0145] When the RAR is correctly received in step 2, the UE is time synchronized with the eNB. The UE transmission in step 3 (referred to as "message 3" or simply "msg3") uses the UL channel radio resources assigned in step 2. If the UE already has a C-RNTI assigned in this cell, the UE includes that C-RNTI in msg3; otherwise, the UE includes the TC-RNTI received in msg2. Additional message exchanges may be required depending on the UE state. For example, if the UE is not known in the eNB, some signaling is required between the eNB and the core network (indicated by the arrow drawn with the dashed line in Figure 8 ).

[0146] In step 4, the eNB sends msg4 via RRC to potentially resolve contention. In particular, msg4 includes the (T)C-RNTI received in msg3 to indicate contention resolution for that specific C-RNTI. If the C-RNTI in msg4 matches the message sent by the UE in msg3, the UE considers the contention resolved. Otherwise, in case of detecting a conflict where the contention is not resolved, the UE shall perform preamble retransmission and initiate random access again. The conflict is detected based on the following aspects:

[0147] · After transmitting msg3 using the C-RNTI assigned by the target cell (e.g., in handover or when the UE is in RRC_CONNECTED), the UE detects that msg4 is not addressed to its C-RNTI and the contention resolution timer expires; or

[0148] · After transmitting msg3 using the TC-RNTI assigned in the RAR, the UE detects that msg4 is addressed to the same TC-RNTI, but the UE identifier in the msg4 payload does not match the UE identifier transmitted in msg3.

[0149] Note that the UE MAC layer does not consider the conflict as a failure situation. Therefore, the upper layers are not aware that a conflict has occurred.

[0150] In addition to the above cases, preamble retransmission is also triggered when the UE transmits a preamble and does not receive a RAR within the RAR time window. In that case, the UE performs preamble power ramp-up and transmits the preamble again. In all these cases, when the RAR time window expires (for CFRA or CBRA) or when a conflict is detected, the UE performs preamble retransmission. The parameters in the RACH-ConfigCommon IE provided to the UE from the eNB via RRC signaling control the number of times the UE should do so. Fig. 9 Shows the ASN.1 data structure defining the exemplary RACH-ConfigCommon IE.

[0151] As described above, the RLF reporting procedure was introduced as part of MRO in LTE Rel-9. In this procedure, the UE records the relevant information at the time of RLF and reports this information to the network later via the target cell to which the UE is finally connected (e.g., after re-establishment). This procedure not only introduces new RRC signaling between the UE and the network (e.g., the target eNB hosting the target cell), but also signaling between nodes in the network (e.g., the X2AP signaling specified in 3GPP TS 36.423). For example, the eNB receiving the RLF report may forward part or all of the report to the eNB that originated the RLF. Generally, the RLF information reported by the UE can include any of the following:

[0152] · Measurement quantities (RSRP, RSRQ) of the serving cell (PCell).

[0153] · Measurement quantities of neighboring cells in different frequencies of different RATs (e.g., EUTRA, UTRA, GERAN, CDMA2000).

[0154] · Measurement quantity associated with a WLAN AP (RSSI).

[0155] · Measurement quantity associated with a Bluetooth beacon (RSSI).

[0156] · Location information, if available (including location coordinates and speed)

[0157] · Global unique identifier of the serving cell, if available, otherwise, the PCI and carrier frequency of the serving cell.

[0158] · Tracking area code of the PCell.

[0159] · Time elapsed since the last receipt of the 'handover command' message.

[0160] · C-RNTI used in the previous serving cell.

[0161] · Whether the UE is configured with a DRB having QCI = 1.

[0162] More specifically, for LTE, the UE's detection and recording of RLF-related parameters are specified in 3GPP TS 36.331 (v15.7.0). The relevant part is provided in the following excerpt, with the parts most relevant to this discussion underlined for emphasis.

[0163] ***Excerpt from 3GPP specification starts***

[0164] 5.3.11.3 Detection of radio link failure

[0165] The UE shall:

[0166] 1> When T310 expires; or

[0167] 1> When T312 expires; or

[0168] 1> When there is a random access problem indication from the MCG MAC when T300, T301, T304, or T311 are not running; or

[0169] 1> When there is an indication from the MCG RLC that the maximum number of retransmissions for an SRB or DRB has been reached (the indication is allowed to be sent on the PCell):

[0170] 2> It is considered that a radio link failure is detected by the MCG, i.e., RLF;

[0171] 2> Except for NB-IoT, by setting its fields as described below, store the following radio link failure information in VarRLF-Report:

[0172] 3> Clear the information contained in VarRLF-Report (if any);

[0173] 3> Set plmn-IdentityList to include the list of EPLMNs stored by the UE (i.e., including RPLMN);

[0174] 3> Based on the measurements collected up to the moment when the UE detects a radio link failure, set measResultLastServCell to include the RSRP and RSRQ of the PCell (if available);

[0175] 3> Set measResultNeighCells to include the best measured cells except PCell, which are sorted The best cell is listed first, and the best cell is listed based on the measurements collected up to the moment the UE detects a radio link failure. Quantity, and set its fields as follows;

[0176] 4> If the UE is configured to perform measurements on one or more EUTRA frequencies, then include measResultListEUTRA;

[0177] 4> If the UE is configured to perform measurement reporting on one or more adjacent UTRA frequencies, include measResultListUTRA;

[0178] 4> If the UE is configured to perform measurement reporting on one or more adjacent GERAN frequencies, include measResultListGERAN;

[0179] 4> If the UE is configured to perform measurement reporting on one or more adjacent CDMA2000 frequencies, include measResultsCDMA2000;

[0180] 4> For each included adjacent cell, include the available optional fields;

[0181] Note 1: The measured quantities are filtered by the L3 filter configured in the mobility measurement configuration. The measurements are based on the time-domain measurement resource limitations (if configured). It is not required to report cells that are on the blacklist.

[0182] …

[0183] The UE may discard the radio link failure information, i.e., release the UE variable VarRLF-Report, 48 hours after the radio link failure is detected, at power-off, or at detachment.

[0184] ***End of excerpt from 3GPP specification***

[0185] After the UE announces RLF and records the relevant information for reporting (e.g., in the variable VarRLF-Report), the UE selects a target cell, and if the UE successfully performs re-establishment to that target cell, it includes an indication in the RRCReestablishmentComplete message that it has an RLF report available. If the eNB serving the target cell wants to receive the RLF report, it sends a UEInformationRequest message with the flag "rlf-ReportReq-r9" to the UE. In response, the UE sends a UEInformationResponse message including the RLF report to the eNB.

[0186] Fig.10 Figure 11 shows the ASN.1 data structure defining the exemplary UEInformationRequest message. Note that the rlf-ReportReq-r9 and rach-ReportReq-r9 fields in UEInformationRequest-r9-IEs are boolean variables that indicate whether the network is requesting the corresponding report from the UE. Additionally, Fig.11A Figure 11-C shows the ASN.1 data structure defining the exemplary UEInformationResponse message sent by the UE in response to the UEInformationRequest message. In particular, the IE RLF-Report-r9 ( Fig. 11B ) and RLF-Report-v9e0 ( Fig. 11C ) contain the RLF report information relevant to this discussion. For example, these IEs can be sent in response to the network requesting the RLF report via rlf-ReportReq-r9.

[0187] Based on the content of the RLF report (e.g., the globally unique identifier of the last serving cell), the eNB serving the target cell (i.e., the new serving cell of the UE) can determine the cell where the originating RLF occurred and forward the RLF report to the source eNB serving that cell. Based on receiving this report, the source eNB can potentially tune the handover-related parameters (e.g., the measurement report trigger threshold) of that cell, including the parameters that led to the RLF of the UE. Two different types of inter-node messages have been standardized in 3GPP TS 36.423 for sending the RLF report between nodes: Radio Link Failure Indication and Handover Report.

[0188] Although the RLF report can include RRM measurements of neighboring cells (e.g., the last served cell of the UE) in different frequencies and / or different RATs (such as EUTRA, UTRA, GERAN, CDMA2000), there is currently no defined way for the UE to classify, sort, and / or prioritize such RRM measurements in the RLF report. Instead, as shown in the underlined part of the above excerpt from 3GPP TS 36.331, the UE is only required to "set measResultNeighCells to include the best measured cells other than the PCell, sorted such that the best cell is listed first, and based on the measurements collected up to the time when the UE detects a radio link failure". This vague requirement can enable different UEs to classify and / or sort the neighboring cell measurements in different ways, resulting in ambiguity in the interpretation by the receiving eNB of the report.

[0189] In addition, for NR, the UE can have measurements based on more than one reference signal (such as SSB and CSI-RS). This can also cause ambiguity in the RLF report. For example, in such a case, the UE does not know whether it should classify the measurements based on only one reference signal and report both measurements or classify based on both reference signals and report accordingly.

[0190] Accordingly, the exemplary embodiments of the present disclosure provide new flexible and effective techniques to enable the UE to classify the available RRM measurements of neighboring cells for inclusion in the RLF report for transmission to a target node (e.g., the new serving cell hosting the UE) after the UE determines an RLF in a previous serving cell (e.g., hosted by a different source node). By relying on clear and decisive classification rules, such techniques reduce and / or eliminate the ambiguity in the network's interpretation of such RLF reports. Thus, such techniques can improve the network's ability to perform corrective actions on the cell where the reported RLF occurred, which can reduce and / or eliminate subsequent RLF failures in such cells.

[0191] Generally speaking, these exemplary techniques can be subdivided into two groups of embodiments (also referred to as "solutions"). In the first group of embodiments, the UE can use one or more measurement quantities (such as RSRP, RSRQ, SINR, etc.) as classification criteria to classify the available RRM measurements per frequency and per reference signal type (such as SSB or CSI-RS). The one or more criteria can be selected from the available measurement quantities configured by the network.

[0192] In some embodiments of these embodiments, the UE is capable of classifying available RRM measurements per frequency and per reference signal type according to the following priorities of the classification criteria: 1) If RSRP is available, then based on RSRP; 2) Otherwise, if RSRQ is available, then based on RSRQ; 3) Otherwise, if SINR is available, then based on SINR; 4) Otherwise based on some default criteria.

[0193] In other embodiments of these embodiments, the UE is capable of creating a list of classified RRM measurements per {RS type, measurement quantity} tuple. For example, if there are three (3) measurement quantities and two (2) RS types, the UE is capable of creating six (6) classified lists for each measurement frequency. In some embodiments, the network is capable of restricting the number of RS types and measurement quantities used for the classification algorithm (e.g., via RRC configuration of the UE). In some embodiments, the UE is capable of restricting the RS types and measurement quantities used as classification criteria based on policies and / or priorities defined by the network or pre-configured in the UE. However, even if a subset of the available RS types and / or measurement quantities is used for classification, the UE is capable of including in the RLF report the values of other measurement quantities and / or RS types (i.e., those measurement quantities and / or RS types not used for classification) of each neighboring cell measured.

[0194] Fig.12 A flowchart showing an exemplary method (e.g., process) for classifying neighboring cell measurements into a list (e.g., measResultNeighCells IE) according to a first set of embodiments. Fig.12 The exemplary method shown in can be performed by a user equipment (e.g., UE, wireless device, MTC device, NB-IoT device, modem, etc. or components thereof). Although Fig.12 Specific boxes are shown in a particular order, the operations of the exemplary method can be performed in an order different from the shown order and can be combined and / or divided into boxes with functionality different from the shown functionality. Optional boxes or operations are indicated by dashed lines.

[0195] In operation 1201, the UE selects a frequency from among the available frequencies having RRM measurements (e.g., the set of frequencies configured via RRC IE MeasObjectNR). In one embodiment, the UE performs measurements on each configured frequency, and in 1201, each of these frequencies is selected in turn. In another embodiment, the UE is capable of selecting frequencies in a particular order (e.g., according to priorities and / or policies configured by the network or pre-configured in the UE).

[0196] In operation 1202, the UE selects an RS type from among the available RS types with RRM measurements (e.g., the RS set configured via the RRC IE MeasObjectNR). In one embodiment, the UE selects each available RS type in sequence. In another embodiment, the UE is able to select the RS type in a specific order (e.g., according to the priority and / or policy configured by the network or pre-configured in the UE). As an example, such a policy may exclude certain RSs for the classification selection in operation 1202 (i.e., these RSs will not be available).

[0197] In operation 1203, the UE selects a measurement quantity from the available measurement quantities (e.g., the measurement quantities configured via the RRC IE MeasObjectNR, such as RSRP, RSRQ, SINR, etc.) as a classification criterion. The UE's selection can be further based on whether the selected measurement quantity is available (e.g., has been measured) for the selected frequency (e.g., in 1201) and the selected RS type (e.g., in 1202). For example, a policy (e.g., configured by the network or pre-configured in the UE) may exclude certain measurement quantities from being selected as classification criteria in operation 1203 (i.e., these measurement quantities will not be available).

[0198] In some embodiments, the measurement quantity can be selected in the priority order configured by the network and / or pre-configured in the UE in operation 1203. For example, the selected measurement quantity can be: 1) RSRP when available for the selected frequency and RS type; 2) otherwise, RSRQ when available; 3) otherwise SINR when available; 4) otherwise a certain default criterion. In other embodiments, the UE can select multiple measurement quantities as classification criteria, which can be used to generate corresponding classification lists (as discussed below).

[0199] In operation 1204, the UE classifies the RRM measurements of the selected frequency based on the currently selected {RS type, measurement quantity} tuple. The classification algorithm can include linear classification, fast classification, etc. In some embodiments, the UE can classify the available RRM measurements with equal values ("ties") based on, for example, an auxiliary classification criterion selected from the available measurement quantities. In the case where the UE selects multiple measurement quantities as classification criteria, the UE can generate classification lists based on each classification criterion in operation 1204.

[0200] In operation 1205, the UE creates (e.g., compiles) a list of the classified measurements per frequency. For example, the UE can append the list determined for the currently selected frequency to the existing list of the classified measurements from the previously selected frequencies. In the case where the UE generates multiple classification lists based on different classification criteria in operation 1204, the UE can create a list for each classification criterion used.

[0201] In some embodiments, when multiple measurement quantities exist for a selected frequency and RS type (e.g., the UE has measured via RSRP and RSRQ), the UE may create / compile multiple lists of classified measurements for each {RS type, measurement quantity} tuple (e.g., {SSB, RSRP}, {CSI-RS, RSRQ}, {SSB, SINR}, etc.).

[0202] In some embodiments, the UE is able to include in the list of RRM measurements only the measurement quantities selected as classification criteria. In other embodiments, although the classification criterion can be one measurement quantity, all other available measurement quantities are also included in the list of classified measurements. For example, when RSRP is used as the classification criterion, the UE selects the cells with the highest RSRP values and includes the available RSRP, RSRQ, and SINR measurement quantities associated with these cells.

[0203] In some embodiments, only the RS types considered in the classification are part of the created list of RRM measurements. In other embodiments, although the RS type considered in the classification can be one RS type, all other available RS types are included in the list of classified measurements. For example, for the selected {CSI-RS, RSRP} tuple, the UE can sort the cells based on CSI-RS RSRP measurements but includes the CSI-RS RSRP measurements as well as any SSB RSRP measurements associated with neighboring cells.

[0204] Note that these embodiments may also be combined in various ways. For example, for the selected {CSI-RS, RSRP} tuple, the UE can sort the cells based on CSI-RS RSRP measurements but includes the CSI-RS RSRP / RSRQ / SINR measurements as well as the SSB RSRP / RSRQ / SINR measurements associated with these cells.

[0205] In optional operation 1206, the UE determines whether all available {RS type, measurement quantity} tuples have been selected for classifying the measurements of the selected frequency. If not, the UE returns to block 1202 to select an available (but previously unselected) {RS type, measurement quantity} tuple. Otherwise, the UE proceeds to operation 1207.

[0206] In operation 1207, the UE determines whether all available frequencies have been selected for classification (i.e., so that all frequencies are configured and the measurements are classified). If not, the UE returns to block 1201 to select an available (but previously unselected) frequency. Otherwise, the process ends.

[0207] In a second set of embodiments, the UE is able to use one or more measurement quantities (e.g., RSRP, RSRQ, SINR, etc.) as classification criteria to classify the available RRM measurements across all frequencies for which RRM measurements are available. The one or more criteria can be selected from the available measurement quantities configured by the network.

[0208] In some embodiments of these embodiments, the UE is able to classify the available RRM measurements for each reference signal type according to the following priority of the classification criteria: 1) If RSRP is available, then based on RSRP; 2) Otherwise, if RSRQ is available, then based on RSRQ; 3) Otherwise, if SINR is available, then based on SINR; 4) Otherwise based on some default criterion.

[0209] In other embodiments of these embodiments, the UE is able to create a list of classified RRM measurements for each {RS type, measurement quantity} tuple. For example, if there are three (3) measurement quantities and two (2) RS types, the UE is able to create six (6) lists classified across all frequencies. In some embodiments, the network is able to limit the number of RS types and measurement quantities used for the classification algorithm (e.g., via RRC configuration of the UE). In some embodiments, the UE is able to limit the RS types and measurement quantities used as classification criteria based on policies and / or priorities defined by the network or pre-configured in the UE. However, even if a subset of the available RS types and / or measurement quantities is used for classification, the UE is able to include in the RLF report the values of the other measurement quantities and / or RS types (i.e., those measurement quantities and / or RS types not used for classification) of each measured neighboring cell.

[0210] Fig.13 A flowchart showing an exemplary method (e.g., process) of classifying neighboring cell measurements into a list (e.g., measResultNeighCells IE) according to a second set of embodiments. Fig.13 The exemplary method shown can be performed by a user equipment (e.g., UE, wireless device, MTC device, NB-IoT device, modem, etc. or their components). Although Fig.13 Specific boxes are shown in a particular order, the operations of the exemplary method can be performed in an order different from the shown order and can be combined and / or divided into boxes with functionality different from the shown functionality. Optional boxes or operations are indicated by dashed lines.

[0211] In operation 1301, the UE selects an RS type (e.g., CSI-RS, SSB, etc.) from among the available RS types with RRM measurements (e.g., the RS set configured via the RRC IE MeasObjectNR). In one embodiment, the UE selects each available RS type in sequence. In another embodiment, the UE can select the RS type in a specific order (e.g., according to the priority and / or policy configured by the network or pre-configured in the UE). As an example, such a policy may exclude a certain RS from the classification selection in operation 1301 (i.e., these RSs will not be available).

[0212] In operation 1302, the UE selects a measurement quantity from among the available measurement quantities (e.g., the measurement quantities configured via the RRC IE MeasObjectNR, such as RSRP, RSRQ, SINR, etc.) as a classification criterion. The UE's selection can be further based on whether the selected measurement quantity is available (e.g., has been measured) for the selected RS type (e.g., in 1301). For example, a policy (e.g., configured by the network or pre-configured in the UE) may exclude certain measurement quantities from being selected as classification criteria in operation 1302 (i.e., these measurement quantities will not be available).

[0213] In some embodiments, the measurement quantity can be selected in the priority order configured by the network and / or pre-configured in the UE in operation 1302. For example, the selected measurement quantity can be: 1) RSRP when available for the selected frequency and RS type; 2) otherwise, RSRQ when available; 3) otherwise SINR when available; 4) otherwise some default criterion. In other embodiments, the UE can select multiple measurement quantities as classification criteria, which can be used to generate corresponding classification lists (as discussed below).

[0214] In operation 1303, the UE classifies the RRM measurements across all available frequencies based on the currently selected {RS type, measurement quantity} tuple. The classification algorithm can include a linear classification algorithm, fast classification, etc. In some embodiments, the UE can classify the available RRM measurements with equal values ("ties") based on, for example, an auxiliary classification criterion selected from the available measurement quantities. In the case where the UE selects multiple measurement quantities as classification criteria, in operation 1303, the UE can generate a classification list based on each classification criterion.

[0215] In operation 1304, the UE creates a list of the classified measurements across all frequencies for the currently selected {RS type, measurement quantity} tuple.

[0216] In the case where the UE generates multiple classification lists based on different classification criteria in operation 1303, the UE can create a list for each classification criterion used.

[0217] In some embodiments, when multiple measurement quantities are available for a selected RS type (e.g., the UE has measured via RSRP and RSRQ), the UE may create / compile multiple lists of classified measurements for each {RS type, measurement quantity} tuple (e.g., {SSB, RSRP}, {CSI-RS, RSRQ}, {SSB, SINR}, etc.).

[0218] In some embodiments, the UE is able to include only the measurement quantities selected as classification criteria in the list of RRM measurements. In other embodiments, although the classification criterion can be one measurement quantity, all other available measurement quantities are also included in the list of classified measurements. For example, when RSRP is used as the classification criterion, the UE selects the cells with the highest RSRP values and includes the available RSRP, RSRQ, and SINR measurement quantities associated with these cells.

[0219] In some embodiments, only the RS types considered in the classification are part of the created list of RRM measurements. In other embodiments, although the RS types considered in the classification can be one RS type, all other available RS types are included in the list of classified measurements. For example, for the selected {CSI-RS, RSRP} tuple, the UE can sort the cells based on CSI-RS RSRP measurements but includes the CSI-RS RSRP measurements as well as any SSB RSRP measurements associated with neighboring cells.

[0220] Note that these embodiments can also be combined in various ways. For example, for the selected {CSI-RS, RSRP} tuple, the UE can sort the cells based on CSI-RS RSRP measurements but includes CSI-RS RSRP / RSRQ / SINR measurements as well as SSB RSRP / RSRQ / SINR measurements associated with these cells.

[0221] In optional operation 1305, the UE determines whether all available {RS type, measurement quantity} tuples have been selected for classification. If not, the UE returns to block 1301 to select available (but previously unselected) {RS type, measurement quantity} tuples. Otherwise, the process ends.

[0222] The above embodiments are further illustrated by Fig.14 showing Fig.14 a flowchart showing an exemplary method (e.g., process) of reporting radio link failures (RLFs) in cells of a wireless network in accordance with various exemplary embodiments of the present disclosure. In particular, aspects of the above various embodiments are Fig.14 features of the operations shown. Fig.14The exemplary method shown can be performed by a user equipment (UE, such as a wireless device, an MTC device, an NB-IoT device, a modem, etc. or components thereof), which operates in a wireless network (such as E-UTRAN, NG-RAN, etc.) including a plurality of cells. Additionally, Fig.14 the exemplary method shown can be used in conjunction with other exemplary methods described herein (such as Figure 12-13 ) to provide the various exemplary beneficial effects described herein. Although Fig.14 specific boxes are shown in a particular order, the operations of the exemplary method can be performed in an order different from the shown order and can be combined and / or divided into boxes having functionality different from the shown functionality. Optional boxes or operations are indicated by dashed lines.

[0223] The exemplary method can include the operation of block 1410, where the UE can perform measurements of a plurality of cells in the wireless network. The plurality of cells can include a serving cell (i.e., for the UE) and a plurality of neighboring cells. The measurement of each (e.g., the plurality of) specific cell is based on one or more types of reference signals (RSs) transmitted in that specific cell. For example, the type of RS can include any one of the following: cell-specific RS (CRS), channel state information RS (CSI-RS), and synchronization / PBCH signal block (SSB). Additionally, the measurements performed by the UE for each cell can include one or more measurement quantities. For example, the one or more measurement quantities can include any one of the following: reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-interference and noise ratio (SINR).

[0224] The exemplary method can further include the operation of block 1420, where the UE can determine that a radio link failure (RLF) has occurred in the serving cell. This determination can be performed in cooperation between the L1 (or PHY) and the RRC layers of the UE, as described above.

[0225] The exemplary method can further include the operation of block 1430, where the UE can classify the neighboring cell measurements into one or more measurement lists based on one or more classification criteria. The classification criteria can be related to one or more of the following: the type of RS based on which the measurement for the corresponding neighboring cell is made; and the measurement quantities available for the measurement of the corresponding neighboring cell. The exemplary method can further include the operation of block 1440, where the UE can transmit an RLF report to a network node, including the one or more measurement lists (e.g., as classified in block 1430). For example, after an RLF, the UE can transmit such a report after it has re-established its connection in the target cell.

[0226] In some embodiments, the classification criterion can include a specific measurement quantity (e.g., RSRP, RSRQ, or SINR). In such embodiments, the classification operation of block 1430 can include the operation of sub-block 1431, where the UE can sort the neighboring cell measurements into the one or more measurement lists based on the value of the specific measurement quantity measured for the corresponding neighboring cell.

[0227] In some of these embodiments, the classification criterion can include multiple measurement quantities, and the one or more measurement lists can include multiple measurement lists associated with the corresponding measurement quantities. In such embodiments, the neighboring cell measurements including the corresponding measurement quantity can be sorted (e.g., in sub-block 1431) into the corresponding measurement list.

[0228] In other embodiments of these embodiments, the classification criterion can further include a specific RS type (e.g., SSB). In such embodiments, sorting the neighboring cell measurements into the one or more measurement lists (e.g., in sub-block 1431) can be based on the value of the specific measurement quantity measured for the corresponding neighboring cell according to the specific RS type. For example, when the value of a specific measurement quantity (e.g., RSRP) is equal for two neighboring cells of a neighboring cell, sorting the measurements of the two neighboring cells (e.g., in sub-block 1431) can be based on the value of one of the following measured for the two neighboring cells:

[0229] · Another measurement quantity (e.g., RSRQ) based on the specific RS type (e.g., SSB); or

[0230] · The specific measurement quantity (e.g., RSRP) based on another RS type (e.g., CRS).

[0231] In other embodiments of these embodiments, the classification criterion can further include multiple measurement quantities, and the one or more measurement lists can include multiple measurement lists associated with the corresponding multiple RS types. In such embodiments, sorting the neighboring cell measurements into the one or more measurement lists (e.g., in sub-block 1431) can be based on the value of the specific measurement quantity measured for the corresponding neighboring cell according to the corresponding RS type.

[0232] In some embodiments, neighboring cell measurements can be performed on multiple carrier frequencies (e.g., in block 1410). In some of these embodiments, the one or more measurement lists include multiple measurement lists associated with the corresponding multiple carrier frequencies, and the neighboring cell measurements made on the corresponding carrier frequencies are sorted (e.g., in block 1431) into the corresponding measurement lists (e.g., as Fig.12 shown).

[0233] In other embodiments of these embodiments, the one or more measurement lists are associated with the plurality of carrier frequencies such that the neighbor cell measurements made on all of the carrier frequencies of the carrier frequencies (e.g., in block 1410) are sorted (e.g., in sub-block 1431) into the one or more measurement lists (e.g., as shown in Fig.13 ). In some embodiments of these embodiments, the one or more measurement lists include a plurality of measurement lists associated with respective pluralities of RS types and with all of the carrier frequencies of the carrier frequencies. In such embodiments, the neighbor cell measurements made on the respective RS types (e.g., in block 1410) are sorted (e.g., in sub-block 1431) into the respective measurement lists.

[0234] In some embodiments, the one or more measurement lists can include a plurality of measurement lists. In such embodiments, the classification operation in block 1430 can include the operation of sub-block 1432, where the UE can combine the plurality of measurement lists into a single measurement list, the combination being in the priority order of one or more of the following associated with the respective measurement lists: carrier frequency, RS type, and measurement quantity. In such embodiments, the RLF report (e.g., transmitted in block 1440) includes a single measurement list.

[0235] In various embodiments, the one or more measurement lists (e.g., included in the RLF report) can include one of the following types of measurement values:

[0236] · The value of a specific measurement quantity used as a classification criterion, which is based on a specific RS type that also serves as a classification criterion;

[0237] · The value of a specific measurement quantity used as a classification criterion, which is based on any one of the RS types;

[0238] · The value of any available measurement quantity, which is based on a specific RS type used as a classification criterion; or

[0239] · The value of any available measurement quantity, which is based on any one of the RS types.

[0240] For example, the UE can selectively include measurement values in addition to the {RS type, measurement quantity} tuples used for classification, as described above.

[0241] In any of the above Figure 12-13 to the extent that any of the features of the classification techniques are not explicitly disclosed as part of the operations shown in Fig.14 , those skilled in the art will know that such features can be incorporated into the classification operations of block 1430 (e.g., sub-blocks) and / or other blocks.

[0242] While the various embodiments have been described above in terms of methods, apparatuses, devices, computer-readable media, and receivers, those of ordinary skill in the art will readily appreciate that such methods can be implemented in a variety of systems, communication devices, computing devices, control devices, apparatuses, non-transitory computer-readable media, etc., through various combinations of hardware and software.

[0243] Fig.15 Figure 4 shows a high-level view of an exemplary 5G network architecture including a Next Generation Radio Access Network (NG-RAN) 1599 and a 5G Core (5GC) 1598. As shown, the NG-RAN 1599 can include gNBs 1510 (e.g., 1510a, b) and ng-eNBs 1520 (e.g., 1520a, b), which are interconnected with each other via respective Xn interfaces. The gNBs and ng-eNBs are also connected to the 5GC 1598 via the NG interface, more specifically to the Access and Mobility Management Function (AMF) 1530 (e.g., AMF 1530a, b) via respective NG-C interfaces and to the User Plane Function (UPF) 1540 (e.g., UPF 1540a, b) via respective NG-U interfaces. In addition, the AMFs 1530a, b can communicate with one or more Policy Control Functions (PCFs, e.g., PCFs 1550a, b) and Network Exposure Functions (NEFs, e.g., NEFs 1560a, b).

[0244] Each of the gNBs 1510 can support an NR radio interface, including Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), or a combination thereof. In contrast, each of the ng-eNBs 1520 can support an LTE radio interface, but is connected to the 5GC via the NG interface, unlike a conventional LTE eNB (such as Figure 1 shown). Each of the gNBs and ng-eNBs can serve a geographical coverage area that includes one or more cells, including cells 1511a-b and 1521a-b as shown in the Fig.15 exemplary. As described above, the gNBs and ng-eNBs can also use various directional beams to provide coverage in the respective cells. Depending on the particular cell in which it is located, the UE 1505 can communicate with the gNB or ng-eNB serving that particular cell via an NR or LTE radio interface, respectively.

[0245] Each of gNBs 1510a, b may include a central (or centralized) unit (CU or gNB-CU) and one or more distributed (or decentralized) units (DU or gNB-DU). The CU is a logical node that hosts higher layer protocols and performs various gNB functions (such as controlling the operation of the DU). Similarly, the DU is a logical node that hosts lower layer protocols and may include various subsets of gNB functions according to the function split. Therefore, each of the CU and DU may include various circuits that perform corresponding functions, including processing circuits, transceiver circuits (e.g., for communication), and power supply circuits. The gNB-CU is connected to its gNB-DU via a corresponding F1 logical interface, but the gNB-CU and the connected gNB-DU are only visible to other gNBs and the 5GC as a gNB. In other words, the F1 interface is not visible outside the gNB-CU.

[0246] Fig.16 A block diagram of an exemplary wireless device or user equipment (UE) 1600 (hereinafter referred to as "UE 1600") according to various embodiments of the present disclosure, including those described above with reference to other figures, is shown. For example, UE 1600 may be configured to perform one or more corresponding operations of the exemplary methods and / or processes described above by executing instructions stored on a computer-readable medium.

[0247] UE 1600 may include a processor 1610 (also referred to as "processing circuit"), which may be operatively connected via a bus 1670 to a program memory 1620 and / or a data memory 1630. The bus may include parallel address and data buses, serial ports, or other methods and / or structures known to those skilled in the art. The program memory 1620 may store software code, programs, and / or instructions ( Fig.16 collectively shown as computer program product 1621), and the software code, programs, and / or instructions, when executed by the processor 1610, may configure and / or facilitate UE 1600 to perform various operations including those described below. For example, the execution of such instructions may configure and / or facilitate UE 1600 to communicate using one or more wired or wireless communication protocols, including one or more wireless communication protocols standardized by 3GPP, 3GPP2, or IEEE, such as those commonly referred to as 5G / NR, LTE, LTE-A, UMTS, HSPA, GSM, GPRS, EDGE, 1xRTT, CDMA2000, 802.11WiFi, HDMI, USB, Firewire, etc., or any other current or future protocol that can be utilized in combination with a radio transceiver 1640, a user interface 1650, and / or a control interface 1660.

[0248] As another example, the processor 1610 is capable of executing program code stored in the program memory 1620, which corresponds to the MAC, RLC, PDCP, and RRC layer protocols standardized by 3GPP (e.g., for NR and / or LTE). As a further example, the processor 1610 is capable of executing program code stored in the program memory 1620, which, together with the radio transceiver 1640, implements corresponding PHY layer protocols such as orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). As another example, the processor 1610 is capable of executing program code stored in the program memory 1620, which, together with the radio transceiver 1640, implements device-to-device (D2D) communication with other compatible devices and / or UEs.

[0249] The program memory 1620 is also capable of including software code that is executed by the processor 1610 to control the functions of the UE 1600, including configuring and controlling various components such as the radio transceiver 1640, the user interface 1650, and / or the host interface 1660. The program memory 1620 is also capable of including one or more application programs and / or modules, including computer-executable instructions for implementing any of the exemplary methods and / or processes described herein. Such software code can be specified or written using any known or future-developed programming language, such as, for example, Java, C++, C, Objective C, HTML, XHTML, machine code, and Assembler, provided that the expected functionality defined, for example, by the method steps being implemented is preserved. As a supplement or alternative, the program memory 1620 can include an external storage arrangement (not shown) remote from the UE 1600 from which instructions can be downloaded into the program memory 1620 located within or removably coupled to the UE 1600 to enable the execution of such instructions.

[0250] The data memory 1630 is capable of including memory areas that enable the processor 1610 to store variables used in the protocols, configurations, controls, and other functions of the UE 1600, including operations corresponding to or incorporating any of the exemplary methods and / or processes described herein. In addition, the program memory 1620 and / or the data memory 1630 can include non-volatile memory (e.g., flash memory), volatile memory (e.g., static or dynamic RAM), or a combination thereof. In addition, the data memory 1630 can include a memory slot through which removable memory cards (e.g., SD cards, memory sticks, Compact Flash, etc.) in one or more formats can be inserted and removed.

[0251] One of ordinary skill in the art will appreciate that the processor 1610 can include multiple individual processors (including, for example, multi-core processors), each of which implements a portion of the functionality described above. In such cases, the multiple individual processors can be collectively connected to the program memory 1620 and the data memory 1630, or individually connected to multiple individual program memories and / or data memories. More generally, one of ordinary skill in the art will appreciate that the various protocols and other functions of the UE 1600 can be implemented in many different computer arrangements, including different combinations of hardware and software, including but not limited to application processors, signal processors, general-purpose processors, multi-core processors, ASICs, fixed and / or programmable digital circuits, analog baseband circuits, radio frequency circuits, software, firmware, and middleware.

[0252] The radio transceiver 1640 can include radio frequency transmitter and / or receiver functionality that facilitates communication of the UE 1600 with other devices that support similar wireless communication standards and / or protocols. In some exemplary embodiments, the radio transceiver 1640 includes one or more transmitters and one or more receivers that enable the UE 1600 to communicate according to various protocols and / or methods proposed by 3GPP and / or other standards bodies for standardization. For example, such functionality can operate in conjunction with the processor 1610 to implement the PHY layer based on OFDM, OFDMA, and / or SC-FDMA technologies, such as described herein for other figures.

[0253] In some exemplary embodiments, the radio transceiver 1640 includes one or more transmitters and one or more receivers that can facilitate communication of the UE 1600 with various LTE, advanced LTE (LTE-A), and / or NR networks according to standards promulgated by 3GPP. In some exemplary embodiments of the present disclosure, the radio transceiver 1640 includes the circuitry, firmware, etc. required for the UE 1600 to also communicate with various NR, NR-U, LTE, LTE-A, LTE-LAA, UMTS, and / or GSM / EDGE networks according to 3GPP standards. In some embodiments, the radio transceiver 1640 can include circuitry that supports D2D communication between the UE 1600 and other compatible devices.

[0254] In some embodiments, radio transceiver 1640 includes the circuitry, firmware, etc. required for UE 1600 to communicate with various CDMA2000 networks according to 3GPP2 standards. In some embodiments, radio transceiver 1640 can be capable of communicating using radio technologies operating in unlicensed frequency bands, such as IEEE 802.11 WiFi operating at frequencies in the 2.4, 5.6, and / or 60 GHz regions. In some embodiments, radio transceiver 1640 can include a transceiver capable of wired communication, such as by using IEEE 802.3 Ethernet technology. Each specific functionality of these embodiments can be coupled to and / or controlled by other circuitry in UE 1600, such as processor 1610 that executes program code stored in program memory 1620 in conjunction with and / or supported by data memory 1630.

[0255] User interface 1650 can take various forms depending on the specific embodiment of UE 1600, or can be completely absent from UE 1600. In some embodiments, user interface 1650 can include a microphone, speaker, slide button, push button, display, touch screen display, mechanical or virtual keypad, mechanical or virtual keyboard, and / or any other user interface features common on mobile phones. In other embodiments, UE 1600 can include a tablet computing device, including a larger touch screen display. In such embodiments, one or more of the mechanical features of user interface 1650 can be replaced by comparable or functionally equivalent virtual user interface features (e.g., virtual keypad, virtual button, etc.) implemented using the touch screen display, as is familiar to those of ordinary skill in the art. In other embodiments, UE 1600 can be a digital computing device, such as a laptop computer, desktop computer, workstation, etc., that includes a mechanical keyboard that can be integrated, detachable, or separable according to a particular exemplary embodiment. Such a digital computing device can also include a touch screen display. Many exemplary embodiments of UE 1600 with a touch screen display can receive user input, such as input related to the exemplary methods and / or processes described herein or otherwise known to those of ordinary skill in the art.

[0256] In some embodiments, the UE 1600 can include an orientation sensor, which can be used in various ways according to the features and functions of the UE 1600. For example, the UE 1600 can use the output of the orientation sensor to determine when the user has changed the physical orientation of the touch screen display of the UE 1600. The indication signal from the orientation sensor can be available to any application executed on the UE 1600, such that when the indication signal indicates an approximate 90-degree change in the physical orientation of the device, the application can automatically change the orientation of the screen display (e.g., from portrait to landscape). In this exemplary manner, the application can keep the screen display in a user-readable manner regardless of the physical orientation of the device. Additionally, the output of the orientation sensor can be used in conjunction with various exemplary embodiments of the present disclosure.

[0257] The control interface 1660 of the UE 1600 can take various forms according to specific exemplary embodiments of the specific interface requirements of the UE 1600 and other devices with which the UE 1600 is expected to communicate and / or be controlled. For example, the control interface 1660 can include an RS-232 interface, a USB interface, an HDMI interface, a Bluetooth interface, an IEEE (“Firewire”) interface, an I 2 C interface, a PCMCIA interface, or the like. In some exemplary embodiments of the present disclosure, the control interface 1660 can include an IEEE 802.3 Ethernet interface such as those described above. In some exemplary embodiments of the present disclosure, the control interface 1660 can include an analog interface circuit, including for example one or more digital-to-analog (D / A) and / or analog-to-digital (A / D) converters.

[0258] Those of ordinary skill in the art will appreciate that the above list of features, interfaces, and radio frequency communication standards is merely exemplary and not limiting of the scope of the present disclosure. In other words, the UE 1600 can include more functionality than Fig.16 shown, including for example a camera and / or a camcorder, a microphone, a media player and / or a recorder, etc. Additionally, the radio transceiver 1640 can include circuitry required to communicate using additional radio frequency communication standards, including Bluetooth, GPS, and / or other standards. Further, the processor 1610 can execute software code stored in the program memory 1620 to control such additional functionality. For example, the orientation speed and / or position estimate output from a GPS receiver can be available to any application executed on the UE 1600, including various exemplary methods and / or computer-readable media according to various exemplary embodiments of the present disclosure.

[0259] Fig.17A block diagram of an exemplary network node 1700 is shown in accordance with various embodiments of the present disclosure, including those described above with reference to other figures. For example, the exemplary network node 1700 can be configured by executing instructions stored on a computer-readable medium to perform one or more operations corresponding to the above-described exemplary methods and / or processes. In some exemplary embodiments, the network node 1700 can include a base station, eNB, gNB, or one or more components thereof. For example, the network node 1700 can be configured as a central unit (CU) and one or more distributed units (DUs) in accordance with the NR gNB architecture specified by 3GPP. More generally, the functionality of the network node 1700 can be distributed across various physical devices and / or functional units, modules, etc.

[0260] The network node 1700 can include a processor 1710 (also referred to as "processing circuitry"), which is operatively connected via a bus 1770 to a program memory 1720 and / or a data memory 1730, and the bus can include parallel address and data buses, serial ports, or other methods and / or structures known to those of ordinary skill in the art.

[0261] The program memory 1720 can store software code, programs, and / or instructions ( Fig.17 collectively shown as computer program product 1721), and the software code, programs, and / or instructions, when executed by the processor 1710, can configure and / or facilitate the network node 1700 to perform various operations. For example, the execution of such stored instructions can configure the network node 1700 to communicate with one or more other devices using protocols in accordance with various embodiments of the present disclosure, including one or more of the above-described exemplary methods and / or processes. The program memory 1720 can also include software code executed by the processor 1710, and the software code can facilitate and specifically configure the network node 1700 to communicate with one or more other devices using other protocols or protocol layers (such as one or more of the PHY, MAC, RLC, PDCP, and RRC layer protocols standardized by 3GPP for LTE, LTE-A, and / or NR, or any other higher-layer protocol utilized in conjunction with the radio network interface 1740 and the core network interface 1750). By way of example and not limitation, the core network interface 1750 can include an S1 interface, and the radio network interface 1740 can include a Uu interface, as standardized by 3GPP. The program memory 1720 can further include software code executed by the processor 1710 to control the functionality of the network node 1700, including configuring and controlling various components, such as the radio network interface 1740 and the core network interface 1750.

[0262] The data memory 1730 can include memory areas that enable the processor 1710 to store variables used in the protocols, configurations, controls, and other functions of the network node 1700. Thus, the program memory 1720 and / or the data memory 1730 can include non-volatile memory (such as flash memory, hard disk, etc.), volatile memory (such as static or dynamic RAM), network-based (such as "cloud") storage devices, or combinations thereof. Those of ordinary skill in the art will appreciate that the processor 1710 can include multiple individual processors (not shown), each of which implements a portion of the above functionality. In such a case, the multiple individual processors can be commonly connected to the program memory 1720 and the data memory 1730, or individually connected to multiple individual program memories and / or data memories. More generally, those of ordinary skill in the art will appreciate that the various protocols and other functions of the network node 1700 can be implemented in many different combinations of hardware and software, including but not limited to application processors, signal processors, general-purpose processors, multi-core processors, ASICs, fixed digital circuits, programmable digital circuits, analog baseband circuits, radio frequency circuits, software, firmware, and middleware.

[0263] The radio network interface 1740 can include a transmitter, a receiver, signal processors, ASICs, antennas, beamforming units, and other circuitry that enables the network node 1700 to communicate with other devices (such as multiple compatible user equipment (UE) in some embodiments). In some embodiments, the interface 1740 can also enable the network node 1700 to communicate with compatible satellites of a satellite communication network. In some exemplary embodiments, the radio network interface 1740 can include: various protocols or protocol layers, such as the PHY, MAC, RLC, PDCP, and / or RRC layer protocols standardized by 3GPP for LTE, LTE-A, LTE-LAA, NR, NR-U, etc.; improvements thereto as described above; or any other higher layer protocol utilized in conjunction with the radio network interface 1740. According to further exemplary embodiments of the present disclosure, the radio network interface 1740 can include a PHY layer based on OFDM, OFDMA, and / or SC-FDMA technologies. In some embodiments, the functionality of such a PHY layer can be provided jointly by the radio network interface 1740 and the processor 1710 (including program code in the memory 1720).

[0264] The core network interface 1750 can include a transmitter, a receiver, and other circuitry that enables the network node 1700 to communicate with other devices in a core network, such as a circuit-switched (CS) and / or packet-switched core (PS) network in some embodiments. In some embodiments, the core network interface 1750 can include the S1 interface standardized by 3GPP. In some embodiments, the core network interface 1750 can include the NG interface standardized by 3GPP. In some exemplary embodiments, the core network interface 1750 can include one or more interfaces to one or more AMFs, SMFs, SGWs, MMEs, SGSNs, GGSNs, and other physical devices including functionality present in GERAN, UTRAN, EPC, 5GC, and CDMA2000 core networks as known to those of ordinary skill in the art. In some embodiments, these one or more interfaces can be multiplexed together on a single physical interface. In some embodiments, the lower layers of the core network interface 1750 can include one or more of asynchronous transfer mode (ATM), Internet protocol over Ethernet (IP), SDH over fiber optic, T1 / E1 / PDH over copper wire, microwave radio, or other wired or wireless transmission technologies known to those of ordinary skill in the art.

[0265] In some embodiments, the network node 1700 can include hardware and / or software that configures and / or facilitates communication of the network node 1700 with other network nodes in the RAN, such as communicating with other eNBs, gNBs, ng-eNBs, en-gNBs, IAB nodes, etc. Such hardware and / or software can be part of the radio network interface 1740 and / or the core network interface 1750, or it can be an independent functional unit (not shown). For example, such hardware and / or software can configure and / or facilitate the network node 1700 to communicate with other RAN nodes via the X2 or Xn interfaces standardized by 3GPP.

[0266] The OA&M interface 1760 can include a transmitter, a receiver, and other circuitry that enables the network node 1700 to communicate with external networks, computers, databases, and the like for the purpose of operation, administration, and maintenance of the network node 1700 or other network devices operationally connected thereto. The lower layers of the OA&M interface 1760 can include one or more of asynchronous transfer mode (ATM), Internet protocol over Ethernet (IP), SDH over fiber optic, T1 / E1 / PDH over copper wire, microwave radio, or other wired or wireless transmission technologies known to those of ordinary skill in the art. Additionally, in some embodiments, one or more of the radio network interface 1740, the core network interface 1750, and the OA&M interface 1760 can be multiplexed together on a single physical interface, such as in the above examples.

[0267] Fig.18 is a block diagram of an exemplary communication network configured to provide an over-the-top (OTT) data service between a host computer and a user equipment (UE) in accordance with one or more exemplary embodiments of the present disclosure. The UE 1810 is capable of communicating with a radio access network (RAN) 1830 via a radio interface 1820, which can be based on the aforementioned protocols, including, for example, LTE, LTE-A, and 5G / NR. For example, the UE 1810 can be configured and / or arranged as shown in the other figures above.

[0268] The RAN 1830 can include one or more terrestrial network nodes (such as base stations, eNBs, gNBs, controllers, etc.) operable in licensed spectrum bands and one or more network nodes operable in unlicensed spectrum (using, for example, LAA or NR-U technologies) such as the 2.4-GHz band and / or the 5-GHz band. In such cases, the network nodes constituting the RAN 1830 can operate in cooperation using licensed and unlicensed spectrum. In some embodiments, the RAN 1830 can include or be capable of communicating with one or more satellites constituting a satellite access network.

[0269] The RAN 1830 can further communicate with the core network 1840 in accordance with the various protocols and interfaces described above. For example, one or more devices (such as base stations, eNBs, gNBs, etc.) constituting the RAN 1830 can communicate with the core network 1840 via the aforementioned core network interface 1650. In some exemplary embodiments, the RAN 1830 and the core network 1840 can be configured and / or arranged as shown in the other figures above. For example, an eNB constituting the E-UTRAN 1830 can communicate with the EPC core network 1840 via an S1 interface such as Figure 1 the interface shown. As another example, a gNB constituting the NR RAN 1830 can communicate with the 5GC core network 1830 via an NG interface.

[0270] The core network 1840 can further communicate with an external packet data network in accordance with the various protocols and interfaces known to those of ordinary skill in the art ( Fig.18is shown as communicating with the Internet 1850. Many other devices and / or networks can also be connected to the Internet 1850 and communicate via the Internet 1850, such as the exemplary host computer 1860. In some exemplary embodiments, the host computer 1860 can use the Internet 1850, the core network 1840, and the RAN 1830 as intermediaries to communicate with the UE 1810. The host computer 1860 can be a server (e.g., an application server) owned and / or controlled by a service provider. The host computer 1860 can be operated by an OTT service provider or by another entity on behalf of the service provider.

[0271] For example, the host computer 1860 can use the facilities of the core network 1840 and the RAN 1830, which may not know the routing of the outgoing / ingoing communications to / from the host computer 1860, to provide over-the-top (OTT) packet data services to the UE 1810. Similarly, the host computer 1860 may not know the routing of the transmission from the host computer to the UE, e.g., the routing of the transmission through the RAN 1830. The exemplary configuration shown can be used Fig.18 to provide various OTT services, including, for example, streaming (one-way) audio and / or video from the host computer to the UE, interactive (two-way) audio and / or video between the host computer and the UE, interactive messaging or social communication, interactive virtual or augmented reality, etc.

[0272] Fig.18 The exemplary network shown can also include measurement processes and / or sensors that monitor network performance metrics, including data rate, latency, and other factors improved by the exemplary embodiments disclosed herein. The exemplary network can also include functionality for reconfiguring the link between endpoints (e.g., the host computer and the UE) in response to changes in the measurement results. Such processes and functionality are known and practiced; if the network hides or abstracts the radio interface from the OTT service provider, the measurements can be facilitated through proprietary signaling between the UE and the host computer.

[0273] The exemplary embodiments described herein provide effective and unambiguous techniques for reporting neighbor cell measurements made by a UE prior to a radio link failure (RLF). By relying on clear and decisive classification rules, such techniques can reduce and / or eliminate the ambiguity in the network's interpretation of such RLF reports. Accordingly, such techniques can improve the network's ability to perform corrective actions on the cell where the reported RLF occurred, which can reduce and / or eliminate subsequent RLF failures in such cells. When used in LTE or NR UEs (such as UE 1810) and eNBs or gNBs (such as the gNBs that make up RAN 1830), the exemplary embodiments described herein can provide various improvements, benefits, and / or advantages to OTT service providers and end users, including more consistent data throughput and less latency, without excessive UE power consumption, service interruptions, and / or other degradations of the user experience.

[0274] The foregoing merely illustrates the principles of the present disclosure. Various modifications and variations to the described embodiments will be apparent to those skilled in the art in light of the teachings herein. Thus, it will be appreciated that those skilled in the art will be able to design numerous systems, arrangements, and processes that, although not explicitly shown or described herein, embody the principles of the present disclosure and are thus within the spirit and scope of the present disclosure. The various exemplary embodiments can be used together and interchangeably, as would be understood by one of ordinary skill in the art.

[0275] As used herein, the term "unit" can have its conventional meaning in the field of electronic devices, electrical devices, and / or electronic apparatuses, and can include, for example, electrical and / or electronic circuits, devices, modules, processors, memories, logic solid-state and / or discrete devices, computer programs or instructions for performing corresponding tasks, processes, calculations, outputs, and / or display functions, etc., such as those described herein.

[0276] Any suitable steps, methods, features, functions, or beneficial effects disclosed herein may be performed by one or more functional units or modules of one or more virtual devices. Each virtual device may include a plurality of these functional units. These functional units may be implemented via a processing circuit, which may include one or more microprocessors or microcontrollers and may include other digital hardware such as a digital signal processor (DSP), dedicated digital logic, and the like. The processing circuit may be configured to execute program code stored in a memory, which may include one or more types of memory, such as read-only memory (ROM), random access memory (RAM), cache memory, flash memory devices, optical storage devices, and the like. The program code stored in the memory includes program instructions for executing one or more telecommunication and / or data communication protocols and instructions for executing one or more techniques described herein. In some implementations, in accordance with one or more embodiments of the present disclosure, the processing circuit may be used to cause the corresponding functional unit to perform the corresponding function.

[0277] As described herein, a device and / or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module including such a chip or chipset; however, this does not exclude the possibility that the functionality of the device or apparatus is not implemented in hardware but is implemented as a software module (such as a computer program or computer program product including an executable software code portion for execution by or running on a processor). Additionally, the functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as a combination of multiple devices and / or apparatuses, whether functionally cooperating with each other or independent of each other. Furthermore, a device and apparatus can be implemented in a distributed manner across the entire system, as long as the functionality of the device or apparatus is preserved. Such and similar principles are considered to be known to those skilled in the art.

[0278] Unless otherwise stated, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0279] In addition, certain terms used in this disclosure (including its specification, drawings, and exemplary embodiments) can be used synonymously in certain cases, including but not limited to, for example, data and information. It should be understood that although these words and / or other words that can be synonymous with each other can be used synonymously herein, there can be cases where such words are not expected to be used synonymously. In addition, to the extent that prior art knowledge has not been explicitly incorporated herein by reference above, it is explicitly incorporated herein in its entirety. All publications cited are incorporated herein by reference in their entirety.

[0280] Exemplary embodiments of the techniques and devices described herein include, but are not limited to, the following enumerated examples:

[0281] E1. A method performed by a user equipment (UE) for reporting a radio link failure (RLF) in a cell of a wireless network, the method comprising:

[0282] Performing measurements of a plurality of cells in a wireless network, wherein:

[0283] The plurality of cells includes a serving cell and a plurality of neighboring cells;

[0284] The measurement of each specific cell is based on one or more types of reference signals (RSs) transmitted in that specific cell; and

[0285] The measurement of each cell includes one or more measurement quantities;

[0286] Determining that a radio link failure (RLF) has occurred in the serving cell;

[0287] Classifying the neighboring cell measurements into one or more measurement lists based on one or more classification criteria related to one or more of the following:

[0288] The type of RS on which the measurement of the corresponding neighboring cell is based; and

[0289] The measurement quantities available for the corresponding neighboring cell;

[0290] Transmitting an RLF report including the one or more measurement lists to a node in the wireless network via a target cell.

[0291] E2. The method of embodiment E1, wherein the measurement of each neighboring cell includes measurements made on a plurality of different carrier frequencies.

[0292] E3. The method of embodiment E2, wherein each measurement list includes only measurements for a single carrier frequency.

[0293] Method of Example E2, wherein each measurement list includes measurements for the plurality of different carrier frequencies.

[0294] Method of any one of Examples E1 - E4, wherein:

[0295] The classification criterion includes a specific measurement quantity; and

[0296] Classifying neighboring cell measurements includes sorting neighboring cell measurements based on the value of the specific measurement quantity measured for the corresponding neighboring cell.

[0297] Method of Example E5, wherein:

[0298] The classification criterion further includes a specific RS type; and

[0299] Classifying neighboring cell measurements includes sorting neighboring cell measurements based on the value of the specific measurement quantity measured for the corresponding neighboring cell according to the specific RS type.

[0300] Method of any one of Examples E1 - E6, wherein the one or more measurement lists include one of the following:

[0301] The value of a specific measurement quantity based on a specific RS type;

[0302] The value of a specific measurement quantity of any type based on an RS type;

[0303] The value of any measurement quantity of a measurement quantity based on a specific RS type; or

[0304] The value of any measurement quantity of any type of measurement quantity based on an RS type.

[0305] Method of any one of Examples E1 - E7, wherein the one or more RS types include any one of the following:

[0306] Cell - specific RS (CRS);

[0307] Channel state information RS (CSI - RS); and

[0308] Synchronization / PBCH signal block (SSB).

[0309] Method of any one of Examples E1 - E8, wherein the one or more measurement quantities include any one of the following:

[0310] Reference signal received power (RSRP);

[0311] Reference signal received quality (RSRQ); and

[0312] Signal - to - interference - plus - noise ratio (SINR).

[0313] E10. A user equipment (UE) configured to report a radio link failure (RLF) in a cell of a wireless network, the UE comprising:

[0314] a transceiver circuit configured to communicate with one or more network nodes in the wireless network; and

[0315] a processing circuit operatively coupled to the transceiver circuit, whereby the processing circuit and the transceiver circuit are configured to perform operations corresponding to any one of the methods of Embodiments E1 - E9.

[0316] E11. A user equipment (UE) configured to report a radio link failure (RLF) in a cell of a wireless network, the UE further arranged to perform operations corresponding to any one of the methods of Embodiments E1 - E9.

[0317] E12. A non - transitory computer - readable medium storing computer - executable instructions that, when executed by a processing circuit of a user equipment (UE), configure the UE to perform operations corresponding to any one of the methods of Embodiments E1 - E9.

[0318] E13. A computer program product comprising computer - executable instructions that, when executed by a processing circuit of a user equipment (UE), configure the UE to perform operations corresponding to any one of the methods of Embodiments E1 - E9.

Claims

1. A method for reporting radio link failure (RLF) in a cell of a radio network, performed by a user equipment (UE), the method comprises: performing (1410) measurements of a plurality of cells in the radio network, wherein: the plurality of cells includes a serving cell and a plurality of neighboring cells, the measurements for each particular cell are based on one or more types of reference signals (RS) transmitted in that particular cell, and the measurements for each particular cell include one or more measurement quantities; determining (1420) that RLF has occurred in the serving cell; classifying (1430) the neighboring cell measurements into one or more measurement lists based on one or more classification criteria related to one or more of the following: the type of RS on which the measurements for the corresponding neighboring cell are based; and the measurement quantities available for the measurements of the corresponding neighboring cell; transmitting (1440) an RLF report including the one or more measurement lists to a network node, wherein: the classification criteria includes a specific measurement quantity; and classifying (1430) the neighboring cell measurements includes sorting (1431) the neighboring cell measurements into the one or more measurement lists based on the value of the specific measurement quantity measured for the corresponding neighboring cell.

2. The method according to claim 1, wherein, the one or more RS types include any one of the following: cell-specific RS, CRS; channel state information RS, CSI-RS; and synchronization / PBCH signal block SSB.

3. The method according to any one of claims 1-2, wherein, the one or more measurement quantities include any one of the following: reference signal received power RSRP; reference signal received quality RSRQ; and signal-to-interference plus noise ratio SINR.

4. The method according to claim 1, wherein: the classification criteria includes a plurality of measurement quantities; the one or more measurement lists include a plurality of measurement lists associated with the corresponding measurement quantities; and the neighboring cell measurements including the corresponding measurement quantity are sorted into the corresponding measurement list.

5. The method according to claim 1, wherein: the classification criteria further includes a specific RS type; and sorting (1431) the neighboring cell measurements into the one or more measurement lists is based on the value of the specific measurement quantity measured for the corresponding neighboring cell according to the specific RS type.

6. The method according to claim 5, wherein, when the values of the specific measurement quantity for two neighboring cells of the neighboring cell are equal, sorting (1431) the measurements for the two neighboring cells is based on the value of one of the following measured for the two neighboring cells: another measurement quantity based on the specific RS type; or the specific measurement quantity based on another RS type.

7. The method according to claim 1, wherein: the classification criteria further includes a plurality of RS types; the one or more measurement lists include a plurality of measurement lists associated with the corresponding plurality of RS types; and Sort the neighboring cell measurements (1431) into the one or more measurement lists based on the value of the specific measurement quantity measured for the respective neighboring cell according to the respective RS type.

8. The method according to any one of claims 4 - 7, wherein, Perform the neighboring cell measurements on multiple carrier frequencies.

9. The method according to claim 8, wherein: The one or more measurement lists include multiple measurement lists associated with respective multiple carrier frequencies; and The neighboring cell measurements made on the respective carrier frequencies are sorted into the respective measurement lists.

10. The method according to claim 8, wherein: The one or more measurement lists are associated with the multiple carrier frequencies; and The neighboring cell measurements made on all of the carrier frequencies of the carrier frequencies are sorted into the one or more measurement lists.

11. The method according to claim 10, wherein: The one or more measurement lists include multiple measurement lists associated with respective multiple RS types and with all of the carrier frequencies of the carrier frequencies; and The neighboring cell measurements made on the respective RS types are sorted into the respective measurement lists.

12. The method according to any one of claims 7 - 11, wherein: The one or more measurement lists include multiple measurement lists; Classifying (1430) the neighboring cell measurements further includes combining (1431) the multiple measurement lists into a single measurement list, the combining in a priority order of one or more of the following associated with the respective measurement lists: carrier frequency, RS type, and measurement quantity; and The RLF report includes the single measurement list.

13. The method according to any one of claims 1 - 12, wherein, The one or more measurement lists include one of the following: The value of a specific measurement quantity used as a classification criterion based on a specific RS type that also serves as a classification criterion; The value of a specific measurement quantity used as a classification criterion based on any type of the RS type; The value of any available measurement quantity based on a specific RS type used as a classification criterion; or The value of any available measurement quantity based on any type of the RS type.

14. A user equipment UE (120, 1505, 1600) configured to report radio link failure RLF in a cell (106, 111, 116, 1511, 1521) of a wireless network (100, 1599), the UE comprises: A radio transceiver circuit (1640) configured to communicate with one or more network nodes (105, 110, 115, 1510, 1520, 1700) in the wireless network; and A processing circuit (1610) operatively coupled to the radio transceiver circuit, whereby the processing circuit and the radio transceiver circuit are configured to: Perform measurements of multiple cells in the wireless network, wherein: The multiple cells include a serving cell and multiple neighboring cells, The measurements for each specific cell are based on one or more types of reference signals RS transmitted in the specific cell, and The measurement for each specific cell includes one or more measurement quantities; Determine that RLF occurs in the serving cell; Classify the neighboring cell measurements into one or more measurement lists based on one or more classification criteria, the one or more classification criteria being related to one or more of the following: The RS type on which the measurement for the corresponding neighboring cell is based; and The measurement quantities available for the measurement of the corresponding neighboring cell; Transmit an RLF report including the one or more measurement lists to a network node, wherein: The classification criteria include a specific measurement quantity; and Classifying (1430) the neighboring cell measurements includes sorting (1431) the neighboring cell measurements into the one or more measurement lists based on the value of the specific measurement quantity measured for the corresponding neighboring cell.

15. The UE according to claim 14, wherein, The processing circuit and the radio transceiver circuit are further configured to perform operations corresponding to any one of the methods according to claims 2 - 13.

16. A user equipment UE (120, 1505, 1600) configured to report a radio link failure RLF in a cell (106, 111, 116, 1511, 1521) of a wireless network (100, 1599), the UE being further arranged to perform operations corresponding to any one of the methods according to claims 1 - 13.

17. A non - transitory computer - readable medium (1620) storing computer - executable instructions, the computer - executable instructions, when executed by a processing circuit (1610) of a user equipment UE (120, 1505, 1600) configured to report a radio link failure RLF in a cell (106, 111, 116, 1511, 1521) of a wireless network (100, 1599), configure the UE to perform operations corresponding to any one of the methods according to claims 1 - 13.

18. A computer program product (1621) including computer - executable instructions, the computer - executable instructions, when executed by a processing circuit (1610) of a user equipment UE (120, 1505, 1600) configured to report a radio link failure RLF in a cell (106, 111, 116, 1511, 1521) of a wireless network (100, 1599), configure the UE to perform operations corresponding to any one of the methods according to claims 1 - 13.

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