Patent Description:
The present disclosure relates to a cellular communications system and, more specifically, to reporting of information related to radio link failure after a successful or failed handover.

In Third Generation Partnership Project (3GPP), voice fallback from New Radio (NR) to Long Term Evolution (LTE) is used to transfer a User Equipment (UE) from NR to LTE during the call establishment procedure. It enables the UE to utilize all NR functionality except voice options in places where the NR network is not optimized for voice services. In order to support various deployment scenarios for obtaining Internet Protocol (IP) Multimedia Subsystem (IMS) voice service, the UE and Next Generation Radio Access Network (NG-RAN) may support the mechanism to direct or redirect the UE from NG-RAN either towards Evolved Universal Terrestrial Radio Access (E-UTRA) connected to the Fifth Generation Core (5GC) (Radio Access Technology, RAT, fallback) or towards the Evolved Packet System (EPS) (Evolved Universal Terrestrial Radio Access Network, E-UTRAN, connected to Evolved Packet Core, EPC, System fallback). During the UE registration procedure, the serving Access and Mobility Management Function (AMF) informs the UE if IMS voice over Packet Switch (PS) session is supported. If a request for establishing the Quality of Service (QoS) Flow for IMS voice reaches the NG-RAN, the NG-RAN responds indicating rejection of the establishment request, and the NG-RAN may trigger one of the following procedures depending on UE capabilities, N26 availability, network configuration, and radio conditions:.

Further details can be found in 3GPP Technical Specification (TS) <NUM> (see, e.g., V17.

<FIG> describes the EPS fallback procedure for IMS voice. A detailed description of <FIG> can be found in section <NUM>. <NUM> of 3GPP TS <NUM> (see, e.g., V17.

A Self-Organizing Network (SON) is an automation technology designed to make the planning, configuration, management, optimization, and healing of mobile radio access networks simpler and faster. SON functionality and behavior has been defined and specified in generally accepted mobile industry recommendations produced by organizations such as 3GPP and the Next Generation Mobile Networks (NGMN).

In 3GPP, the processes within the SON area are classified into self-configuration process and self-optimization process. The self-configuration process is the process where newly deployed nodes are configured by automatic installation procedures to get the necessary basic configuration for system operation. This process works in pre-operational state. The pre-operational state is understood as the state from when the evolved Node B (eNB) is powered up and has backbone connectivity until the radio frequency (RF) transmitter is switched on.

<FIG> illustrates ramifications of Self-Configuration /Self-Optimization functionality (from 3GPP TS <NUM> figure <NUM>-<NUM>). As illustrated in <FIG>, functions handled in the pre-operational state like:.

are covered by the Self Configuration process.

The self-optimization process is defined as the process where UE and access node measurements and performance measurements are used to auto-tune the network. This process works in operational state. The operational state is understood as the state where the RF interface is additionally switched on. As described in <FIG>, functions handled in the operational state like:.

are covered by the Self Optimization process.

In LTE, support for Self-Configuration and Self-Optimization is specified, as described in 3GPP TS <NUM> section <NUM>, including features such as Dynamic configuration, Automatic Neighbor Relation (ANR), Mobility load balancing, Mobility Robustness Optimization (MRO), Random Access Channel (RACH) optimization and support for energy saving.

In NR, support for Self-Configuration and Self-Optimization is specified as well, starting with Self-Configuration features such as Dynamic configuration, Automatic Neighbor Relation (ANR) in Rel-<NUM>, as described in 3GPP TS <NUM> section <NUM>. In NR Rel-<NUM>, more SON features are being specified, including Self-Optimization features such as Mobility Robustness Optimization (MRO).

Seamless handovers are a key feature of 3GPP technologies. Successful handovers ensure that the UE moves around in the coverage area of different cells without causing too many interruptions in the data transmission. However, there will be scenarios when the network fails to handover the UE to the 'correct' neighbor cell in time and, in such scenarios, the UE will declare a Radio Link Failure (RLF) or Handover Failure (HOF).

Upon HOF and RLF, the UE may take autonomous actions i.e., try to select a cell and initiate reestablishment procedure so that we make sure the UE is trying to get back as soon as it can, so that it can be reachable again. The RLF will cause a poor user experience as the RLF is declared by the UE only when it realizes that there is no reliable communication channel (radio link) available between itself and the network. Also, reestablishing the connection requires signaling with the newly selected cell (random access procedure, Radio Resource Control (RRC) Reestablishment Request, RRC Reestablishment RRC Reestablishment Complete, RRC Reconfiguration, and RRC Reconfiguration Complete) and adds some latency, until the UE can exchange data with the network again.

According to the 3GPP specifications (see 3GPP TS <NUM>), the possible causes for RLF could be one of the following:.

As RLF leads to reestablishment which degrades performance and user experience, it is in the interest of the network to understand the reasons for RLF and try to optimize mobility related parameters (e.g., trigger conditions of measurement reports) to avoid later RLFs. Before the standardization of MRO related report handling in the network, only the UE was aware of some information associated to what the radio quality looked like at the time of RLF, what the actual reason for declaring RLF was, etc. For the network to identify the reason for the RLF, the network needs more information, both from the UE and also from the neighboring base stations.

As part of the MRO solution in LTE, the RLF reporting procedure was introduced in the RRC specification in Rel-<NUM> RAN2 work. That has impacted the RRC specifications (3GPP TS <NUM>) in the sense that it was standardized that the UE would log relevant information at the moment of an RLF and later report to a target cell to which the UE succeeds to connect (e.g., after reestablishment). That has also impacted the inter-gNodeB interface, i.e., X2AP specifications (3GPP TS <NUM>), as an eNodeB receiving an RLF report could forward to the eNodeB where the failure has been originated.

For the RLF report generated by the UE, its contents have been enhanced with more details in the subsequent releases. The measurements included in the measurement report based on the latest LTE RRC specification (see TS <NUM> V17. <NUM>) are:.

After the RLF is declared, the RLF report is logged and include in the VarRLF-Report and, once the UE selects a cell and succeeds with a reestablishment, the UE includes an indication that it has an RLF report available in the RRC Reestablishment Complete message, to make the target cell aware of that availability. Then, upon receiving an UEInformationRequest message with a flag "rlf-ReportReq-r9", the UE includes the RLF report (stored in a UE variable VarRLF-Report, as described above) in an UEInformationResponse message and sends the UEInformationResponse message to the network.

Based on the RLF report from the UE and the knowledge about the cell to which the UE reestablished itself, the original source cell can deduce whether the RLF was caused due to a coverage hole or due to handover associated parameter configurations. If the RLF was deemed to be due to handover associated parameter configurations, the original serving cell can further classify the handover related failure as too-early, too-late, or handover to wrong cell classes. These handover failure classes are explained in brief below.

Document <CIT>, which is considered relevant prior art for the present application, discloses a handover procedure in which the UE is configured with a MobilityFromNRCommand comprising a voice fallback indication.

Further embodiments are set out in the dependent claims.

There currently exist certain challenge(s). A New Radio (NR) node triggers a User Equipment (UE) to perform inter-Radio Access Technology (RAT) handover to Evolved Universal Terrestrial Radio Access (E-UTRA) (i.e., to Long Term Evolution (LTE)) for normal mobility related reasons (going out of coverage of NR) or for voice fallback purposes. These two types of handovers from NR to LTE could involve different mobility decision making algorithms as they could be triggered based on different input information available to the source NR node.

Consider the following scenarios with different UEs:.

Based on the current RLF report contents, the handover from Cell-A to Cell-B might be deemed 'too early' or 'handover to wrong cell'. However, based on the current RLF report contents, it is not possible to identify whether the previously completed handover was for voice fallback purpose or not. This is required to perform NR to LTE inter-RAT handover parameter optimization as the NR node might use different handover parameters for normal NR-LTE mobility against the voice fallback related NR-LTE mobility (because the amount of information available on the NR node is much less for scenario-<NUM> compared to scenario-<NUM>).

Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. Systems and methods disclosed herein relate to enhancement of an RLF report with an indication indicating whether the last successfully completed handover is a voice fallback related NR to LTE handover or other type of NR to LTE handover.

In another scenario, the UE includes an indication in an RLF report that the UE experienced a HO failure that led to suitable E-UTRA cell selection (due to the voice fallback configuration in MobilityFromNR command) before experiencing current RLF.

In one embodiment, a method performed by a UE comprises one or more of the following:.

In one embodiment, the first report is an RLF report. In one embodiment, the RLF report is logged and included in a VarRLF-Report. In one embodiment, once the UE selects a cell and succeeds with a reestablishment, the UE sends the RLF report to a respective network node. More specifically, in one embodiment, once the UE selects a cell and succeeds with a reestablishment, the UE includes an indication that it has an RLF report available in an RRC Reestablishment Complete message, which makes the target cell aware of that availability. Then, upon receiving an UEInformationRequest message with a flag (e.g., flag "rlf-ReportReq-r9"), the UE includes the RLF report (stored in a UE variable VarRLF-Report, as described above) in an UEInformationResponse message and sends the UEInformationResponse message to the network.

In another embodiment, a second method performed by a UE comprises one or more of the following:.

Certain embodiments may provide one or more of the following technical advantage(s). Based on the additional contents of the RLF report as proposed in the embodiments described herein, the network could identify whether the last completed handover was a voice fallback handover or not and thus, if such a handover is classified as too-early handover or handover-to-wrong cell, then the network node can optimize the voice fallback handover related mobility parameters.

In some embodiments, by including a flag in the RLF report that the UE failed in a handover that led to E-UTRA cell selection (due to the voice fallback indication/configuration in MobilityFromNR command) before the current RLF, the NR node realizes that the voice fallback procedure was not effective (even if successful) since the UE failed after selection and connection to an LTE cell after HO failure.

Systems and methods are disclosed herein that relate to enhancement of an RLF report with an indication indicating whether the last successfully completed handover is a voice fallback related RAT <NUM> (e.g., NR) to RAT <NUM> (e.g., LTE) handover or other type of RAT <NUM> (e.g., NR) to RAT <NUM> (e.g., LTE) handover.

In another scenario, a UE includes an indication in an RLF report that the UE experienced a HO failure that led to suitable EUTRA cell selection (due to the voice fallback configuration in MobilityFromNR command) before experiencing current RLF.

<FIG> is a flow chart that illustrates the operation of a UE in accordance with one embodiment of the present disclosure. Optional steps are represented by dashed lines/boxes. As illustrated, the UE receives a configuration from a first network node (e.g., a source NR network node such as, e.g., a next generation Node B (gNB)) belonging to a first radio access technology (e.g., NR) to perform handover to a second network node (e.g., an LTE network node such as, e.g., an evolved or enhanced Node B (eNB)) belonging to a second radio access technology (e.g., LTE), the configuration comprising indication indicating voice fallback purpose (e.g., MobilityFromNR with voice fallback indication) (step <NUM>).

The UE connects to a cell served by the second network node, in accordance with the received configuration (step <NUM>). The UE declares RLF in the cell served by the second network node (step <NUM>) and, responsive thereto, stores a first set of information associated to the RLF in a first report (e.g., an RLF report) (step <NUM>). The first set of information comprises an indication that indicates whether the last completed handover from the first network node to the second network node was for voice fallback purpose. In this example, since the last completed handover was for voice fallback purpose, the indication indicates that the last completed handover from the first network node to the second network node was for voice fallback purpose. In one embodiment, the first report is an RLF report. In one embodiment, the RLF report is logged and included in a VarRLF-Report (in step <NUM>).

In one embodiment, the UE selects a cell and succeeds with a reestablishment to the selected cell (step <NUM>) and sends the RLF report to a respective network node (step <NUM>). More specifically, in one embodiment, once the UE selects a cell and succeeds with a reestablishment, the UE includes an indication that it has an RLF report available in an RRC Reestablishment Complete message (step 310A), which makes the target cell aware of that availability. Then, upon receiving an UEInformationRequest message with a flag (e.g., flag "rlf-ReportReq-r9") (step 310B), the UE includes the RLF report (stored in a UE variable VarRLF-Report, as described above) in an UEInformationResponse message and sends the UEInformationResponse message to the network (step 310C).

<FIG> is a flow chart that illustrates the operation of a UE in accordance with another embodiment of the present disclosure. Optional steps are represented by dashed lines/boxes. As illustrated, the UE receives a configuration from a first network node (e.g., a source NR network node such as, e.g., a gNB) belonging to a first radio access technology (e.g., NR) to perform handover to a second network node (e.g., an LTE network node such as, e.g., a gNB) belonging to a second radio access technology (e.g., LTE), the configuration comprising indication indicating voice fallback purpose (e.g., MobilityFromNR with voice fallback indication) (step <NUM>). The UE fails to connect (e.g., failure in handover execution) toward a cell served by the second network node (step <NUM>). The UE finds a suitable EUTRA cell due to being configured with voice fall back indication as part of received MobilityFromNR command and connects to this selected EUTRA cell (step <NUM>).

The UE declares an RLF in the selected EUTRA cell after cell selection and connection to the selected EUTRA cell (step <NUM>). In response thereto, the UE stores a first set of information associated to the RLF in a first report (step <NUM>). The first set of information comprises at least an indication indicating that the serving cell in which this RLF occurred was selected as part of cell selection due to a voice fallback indication received as part of MobilityFromNR command. In one embodiment, the first report is an RLF report. In one embodiment, the RLF report is logged and included in a VarRLF-Report (in step <NUM>).

In one embodiment, the UE selects a cell and succeeds with a reestablishment to the selected cell (step <NUM>) and sends the RLF report to a respective network node (step <NUM>). More specifically, in one embodiment, once the UE selects a cell and succeeds with a reestablishment, the UE includes an indication that it has an RLF report available in an RRC Reestablishment Complete message (step 412A), which makes the target cell aware of that availability. Then, upon receiving an UEInformationRequest message with a flag (e.g., flag "rlf-ReportReq-r9") (step 412B), the UE includes the RLF report (stored in a UE variable VarRLF-Report, as described above) in an UEInformationResponse message and sends the UEInformationResponse message to the network (step 412C).

<FIG> is a flow chart that illustrates the operation of a network node (e.g., a base station such as, e.g., an gNB or eNB) in accordance with one embodiment of the present disclosure. Optional steps are represented by dashed lines/boxes. As illustrated, the network node receives, from a UE, an RLF report comprising either: (a) an indication that a last completed handover for a first network node to a second network node was for voice fallback purpose or (b) an indication that a cell in which the radio link failure has occurred was selected as part of cell reselection due to voice fallback indication (step <NUM>). The network node may then perform one or more actions based on the RLF report (step <NUM>). The one or more actions may include, e.g., sending the RLF report or information from the RLF report to one or more other network nodes (e.g., the first network node). Based on the RLF report, the network (e.g., the network node or some other network node to which the RLF report or information contained in the RLF report is sent) could, e.g., identify whether the last completed handover was a voice fallback handover or not and thus, if such a handover is classified as too-early handover or handover-to-wrong cell, then the network can optimize the voice fallback handover related mobility parameters. In some embodiments, by including a flag in the RLF report that the UE failed in a handover that led to EUTRA cell selection (due to the voice fallback indication/configuration in MobilityFromNR command) before the current RLF, the NR node realizes that the voice fallback procedure was not effective (even if successful) since the UE failed after selection and connection to an LTE cell after HO failure and, e.g., one or more appropriate actions may be taken.

An example implementation is given below (TS <NUM> v17. <NUM> is taken as the baseline and additions are shown with bold, underlined text). <IMG>
<IMG>
<IMG>
<IMG>.

<FIG> shows an example of a communication system <NUM> in which embodiments of the present disclosure may be implemented.

In the example, the communication system <NUM> includes a telecommunication network <NUM> that includes an access network <NUM>, such as a Radio Access Network (RAN), and a core network <NUM>, which includes one or more core network nodes <NUM>. The access network <NUM> includes one or more access network nodes, such as network nodes 610A and 610B (one or more of which may be generally referred to as network nodes <NUM>), or any other similar Third Generation Partnership Project (3GPP) access node or non-3GPP Access Point (AP). The network nodes <NUM> facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 612A, 612B, 612C, and 612D (one or more of which may be generally referred to as UEs <NUM>) to the core network <NUM> over one or more wireless connections.

Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-Concealing Function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

In that sense, the communication system <NUM> may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable Second, Third, Fourth, or Fifth Generation (<NUM>, <NUM>, <NUM>, or <NUM>) standards, or any applicable future generation standard (e.g., Sixth Generation (<NUM>)); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) <NUM> standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any Low Power Wide Area Network (LPWAN) standards such as LoRa and Sigfox.

Accordingly, the telecommunication network <NUM> may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network <NUM>. For example, the telecommunication network <NUM> may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing enhanced Mobile Broadband (eMBB) services to other UEs, and/or massive Machine Type Communication (mMTC)/massive Internet of Things (IoT) services to yet further UEs.

In some examples, the UEs <NUM> are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network <NUM> on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network <NUM>. Additionally, a UE may be configured for operating in single- or multi-Radio Access Technology (RAT) or multi-standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e. be configured for Multi-Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC).

In the example, a hub <NUM> communicates with the access network <NUM> to facilitate indirect communication between one or more UEs (e.g., UE 612C and/or 612D) and network nodes (e.g., network node 610B). In some examples, the hub <NUM> may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub <NUM> may be a broadband router enabling access to the core network <NUM> for the UEs. As another example, the hub <NUM> may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes <NUM>, or by executable code, script, process, or other instructions in the hub <NUM>. As another example, the hub <NUM> may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub <NUM> may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub <NUM> may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub <NUM> then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub <NUM> acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy IoT devices.

The hub <NUM> may have a constant/persistent or intermittent connection to the network node 610B. The hub <NUM> may also allow for a different communication scheme and/or schedule between the hub <NUM> and UEs (e.g., UE 612C and/or 612D), and between the hub <NUM> and the core network <NUM>. In other examples, the hub <NUM> is connected to the core network <NUM> and/or one or more UEs via a wired connection. Moreover, the hub <NUM> may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network <NUM> and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes <NUM> while still connected via the hub <NUM> via a wired or wireless connection. In some embodiments, the hub <NUM> may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 610B. In other embodiments, the hub <NUM> may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and the network node 610B, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

<FIG> shows a UE <NUM> in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged, and/or operable to communicate wirelessly with network nodes and/or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, Voice over Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart device, wireless Customer Premise Equipment (CPE), vehicle-mounted or vehicle embedded/integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and/or an enhanced MTC (eMTC) UE.

A UE may support Device-to-Device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle-to-Everything (V2X).

The UE <NUM> includes processing circuitry <NUM> that is operatively coupled via a bus <NUM> to an input/output interface <NUM>, a power source <NUM>, memory <NUM>, a communication interface <NUM>, and/or any other component, or any combination thereof.

The processing circuitry <NUM> may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry <NUM> may include multiple Central Processing Units (CPUs).

Delivering power may be, for example, for charging the power source <NUM>.

The memory <NUM> may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth.

The memory <NUM> may be configured to include a number of physical drive units, such as Redundant Array of Independent Disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, High Density Digital Versatile Disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, Holographic Digital Data Storage (HDDS) optical disc drive, external mini Dual In-line Memory Module (DIMM), Synchronous Dynamic RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and/or Internet Protocol Multimedia Services Identity Module (ISIM), other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as a 'SIM card. ' The memory <NUM> may allow the UE <NUM> to access instructions, application programs, and the like stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system, may be tangibly embodied as or in the memory <NUM>, which may be or comprise a device-readable storage medium.

Moreover, the transmitter <NUM> and receiver <NUM> may be coupled to one or more antennas (e.g., the antenna <NUM>) and may share circuit components, software, or firmware, or alternatively be implemented separately.

In the illustrated embodiment, communication functions of the communication interface <NUM> may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, NFC, location-based communication such as the use of the Global Positioning System (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and/or standards, such as IEEE <NUM>, Code Division Multiplexing Access (CDMA), Wideband CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol/Internet Protocol (TCP/IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface <NUM>, or via a wireless connection to a network node.

As another example, a UE comprises an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection.

A UE, when in the form of an IoT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application, and healthcare. Non-limiting examples of such an IoT device are a device which is or which is embedded in: a connected refrigerator or freezer, a television, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door/window sensor, a flood/moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or itemtracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an IoT device comprises circuitry and/or software in dependence of the intended application of the IoT device in addition to other components as described in relation to the UE <NUM> shown in <FIG>.

As yet another specific example, in an IoT scenario, a UE may represent a machine or other device that performs monitoring and/or measurements and transmits the results of such monitoring and/or measurements to another UE and/or a network node. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be, or be integrated in, a drone and provide the drone's speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g., by controlling an actuator) to increase or decrease the drone's speed. The first and/or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator and handle communication of data for both the speed sensor and the actuators.

<FIG> shows a network node <NUM> in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged, and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment in a telecommunication network. Examples of network nodes include, but are not limited to, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), and NR Node Bs (gNBs)).

BSs may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto BSs, pico BSs, micro BSs, or macro BSs. A BS may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio BS such as centralized digital units and/or Remote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio BS may also be referred to as nodes in a Distributed Antenna System (DAS).

Other examples of network nodes include multiple Transmission Point (multi-TRP) <NUM> access nodes, Multi-Standard Radio (MSR) equipment such as MSR BSs, network controllers such as Radio Network Controllers (RNCs) or BS Controllers (BSCs), Base Transceiver Stations (BTSs), transmission points, transmission nodes, Multi-Cell/Multicast Coordination Entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and/or Minimization of Drive Tests (MDTs).

The network node <NUM> includes processing circuitry <NUM>, memory <NUM>, a communication interface <NUM>, and a power source <NUM>. The network node <NUM> may be composed of multiple physically separate components (e.g., a Node B component and an RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. For example, a single RNC may control multiple Node Bs. In such a scenario, each unique Node B and RNC pair may in some instances be considered a single separate network node. In some embodiments, the network node <NUM> may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory <NUM> for different RATs) and some components may be reused (e.g., an antenna <NUM> may be shared by different RATs). The network node <NUM> may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node <NUM>, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node <NUM>.

The processing circuitry <NUM> may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, or any other suitable computing device, resource, or combination of hardware, software, and/or encoded logic operable to provide, either alone or in conjunction with other network node <NUM> components, such as the memory <NUM>, to provide network node <NUM> functionality.

In some embodiments, the processing circuitry <NUM> includes a System on a Chip (SOC). In some embodiments, the processing circuitry <NUM> includes one or more of Radio Frequency (RF) transceiver circuitry <NUM> and baseband processing circuitry <NUM>. In some embodiments, the RF transceiver circuitry <NUM> and the baseband processing circuitry <NUM> may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of the RF transceiver circuitry <NUM> and the baseband processing circuitry <NUM> may be on the same chip or set of chips, boards, or units.

The memory <NUM> may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, RAM, ROM, mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD), or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device-readable, and/or computer-executable memory devices that store information, data, and/or instructions that may be used by the processing circuitry <NUM>. In some embodiments, the processing circuitry <NUM> and the memory <NUM> are integrated.

The radio front-end circuitry <NUM> comprises filters <NUM> and amplifiers <NUM>. The radio front-end circuitry <NUM> may be connected to the antenna <NUM> and the processing circuitry <NUM>. The radio front-end circuitry <NUM> may be configured to condition signals communicated between the antenna <NUM> and the processing circuitry <NUM>. The radio front-end circuitry <NUM> may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters <NUM> and/or the amplifiers <NUM>. In other embodiments, the communication interface <NUM> may comprise different components and/or different combinations of components.

In certain alternative embodiments, the network node <NUM> does not include separate radio front-end circuitry <NUM>; instead, the processing circuitry <NUM> includes radio front-end circuitry and is connected to the antenna <NUM>. In still other embodiments, the communication interface <NUM> includes the one or more ports or terminals <NUM>, the radio front-end circuitry <NUM>, and the RF transceiver circuitry <NUM> as part of a radio unit (not shown), and the communication interface <NUM> communicates with the baseband processing circuitry <NUM>, which is part of a digital unit (not shown).

The antenna <NUM>, the communication interface <NUM>, and/or the processing circuitry <NUM> may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by the network node <NUM>. Any information, data, and/or signals may be received from a UE, another network node, and/or any other network equipment. Similarly, the antenna <NUM>, the communication interface <NUM>, and/or the processing circuitry <NUM> may be configured to perform any transmitting operations described herein as being performed by the network node <NUM>. Any information, data, and/or signals may be transmitted to a UE, another network node, and/or any other network equipment.

The power source <NUM> provides power to the various components of the network node <NUM> in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). For example, the network node <NUM> may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source <NUM>.

As used herein, the host <NUM> may be or comprise various combinations of hardware and/or software including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm.

The host <NUM> includes processing circuitry <NUM> that is operatively coupled via a bus <NUM> to an input/output interface <NUM>, a network interface <NUM>, a power source <NUM>, and memory <NUM>. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as <FIG>, such that the descriptions thereof are generally applicable to the corresponding components of the host <NUM>.

The memory <NUM> may include one or more computer programs including one or more host application programs <NUM> and data <NUM>, which may include user data, e.g. data generated by a UE for the host <NUM> or data generated by the host <NUM> for a UE. The host application programs <NUM> may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), Moving Picture Experts Group (MPEG), VP9) and audio codecs (e.g., Free Lossless Audio Codec (FLAC), Advanced Audio Coding (AAC), MPEG, G. <NUM>), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, and heads-up display systems). Accordingly, the host <NUM> may select and/or indicate a different host for Over-The-Top (OTT) services for a UE. The host application programs <NUM> may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (DASH or MPEG-DASH), etc..

In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices, and networking resources. Some or all of the functions described herein may be implemented as virtual components executed by one or more Virtual Machines (VMs) implemented in one or more virtual environments <NUM> hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host.

Applications <NUM> (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment <NUM> to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

Hardware <NUM> includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers <NUM> (also referred to as hypervisors or VM Monitors (VMMs)), provide VMs 1008A and 1008B (one or more of which may be generally referred to as VMs <NUM>), and/or perform any of the functions, features, and/or benefits described in relation with some embodiments described herein. The virtualization layer <NUM> may present a virtual operating platform that appears like networking hardware to the VMs <NUM>.

The VMs <NUM> comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer <NUM>. Different embodiments of the instance of a virtual appliance <NUM> may be implemented on one or more of the VMs <NUM>, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as Network Function Virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers and customer premise equipment.

Each of the VMs <NUM>, and that part of the hardware <NUM> that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs <NUM>, forms separate virtual network elements.

The hardware <NUM> may be implemented in a standalone network node with generic or specific components. The hardware <NUM> may implement some functions via virtualization. Alternatively, the hardware <NUM> may be part of a larger cluster of hardware (e.g., such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration <NUM>, which, among others, oversees lifecycle management of the applications <NUM>. In some embodiments, the hardware <NUM> is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a RAN or a BS. In some embodiments, some signaling can be provided with the use of a control system <NUM> which may alternatively be used for communication between hardware nodes and radio units.

<FIG> shows a communication diagram of a host <NUM> communicating via a network node <NUM> with a UE <NUM> over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as the UE 612A of <FIG> and/or the UE <NUM> of <FIG>), the network node (such as the network node 610A of <FIG> and/or the network node <NUM> of <FIG>), and the host (such as the host <NUM> of <FIG> and/or the host <NUM> of <FIG>) discussed in the preceding paragraphs will now be described with reference to <FIG>.

Like the host <NUM>, embodiments of the host <NUM> include hardware, such as a communication interface, processing circuitry, and memory. The host <NUM> also includes software, which is stored in or is accessible by the host <NUM> and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE <NUM> connecting via an OTT connection <NUM> extending between the UE <NUM> and the host <NUM>.

The network node <NUM> includes hardware enabling it to communicate with the host <NUM> and the UE <NUM> via a connection <NUM>. The connection <NUM> may be direct or pass through a core network (like the core network <NUM> of <FIG>) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks.

The UE <NUM> includes hardware and software, which is stored in or accessible by the UE <NUM> and executable by the UE's processing circuitry. The software includes a client application, such as a web browser or operator-specific "app" that may be operable to provide a service to a human or non-human user via the UE <NUM> with the support of the host <NUM>. In the host <NUM>, an executing host application may communicate with the executing client application via the OTT connection <NUM> terminating at the UE <NUM> and the host <NUM>.

The OTT connection <NUM> may extend via the connection <NUM> between the host <NUM> and the network node <NUM> and via a wireless connection <NUM> between the network node <NUM> and the UE <NUM> to provide the connection between the host <NUM> and the UE <NUM>. The connection <NUM> and the wireless connection <NUM>, over which the OTT connection <NUM> may be provided, have been drawn abstractly to illustrate the communication between the host <NUM> and the UE <NUM> via the network node <NUM>, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

The transmission may pass via the network node <NUM> in accordance with the teachings of the embodiments described throughout this disclosure.

One or more of the various embodiments improve the performance of OTT services provided to the UE <NUM> using the OTT connection <NUM>, in which the wireless connection <NUM> forms the last segment.

As another example, the host <NUM> may store or control access to media content such as video, audio, VR, or AR which it can broadcast, multicast, or unicast to UEs. As other examples, the host <NUM> may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing, and/or transmitting data.

In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection <NUM> between the host <NUM> and the UE <NUM> in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection <NUM> may be implemented in software and hardware of the host <NUM> and/or the UE <NUM>. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection <NUM> passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or by supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection <NUM> may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not directly alter the operation of the network node <NUM>. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency, and the like by the host <NUM>. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or 'dummy' messages, using the OTT connection <NUM> while monitoring propagation times, errors, etc..

It is to be understood that these computing devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions, and methods disclosed herein. Determining, calculating, obtaining, or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box or nested within multiple boxes, in practice computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components.

Claim 1:
A method performed by a User Equipment, UE, the method comprising:
receiving (<NUM>), from a first network node belonging to a first radio access technology, a configuration to perform a handover to a second network node belonging to a second radio access technology, the configuration comprising an indication that indicates that the handover is for voice fallback purpose;
connecting (<NUM>) to a cell served by the second network node, responsive to receiving (<NUM>) the configuration;
after successfully completing the handover to the cell served by the second network node, declaring (<NUM>) a radio link failure in the cell served by the second network node;
responsive to declaring (<NUM>) the radio link failure in the cell served by the second network node and the indication that indicates that the handover is for voice fallback purpose, storing (<NUM>) information associated to the radio link failure in a report, the information comprising an indication that a last successfully completed handover from the first network node to the second network node was for voice fallback purpose; and
sending the report to a network node associated to a target cell to which the UE succeeds to connect at reestablishment.