Method and apparatus for including information about selected cell (appropriate or acceptable cell) in failure report

Abstract

Systems and methods for including information about a selected cell in a failure report are disclosed. In one embodiment, a method performed by a wireless terminal includes receiving a configuration from a first cell to perform a handover to a second cell, the configuration including an indication indicating a voice fallback purpose. The method further includes attempting to connect to a second cell using a mobility procedure, determining that a failure has occurred, and storing information associated with the failure in a first report. The method further comprises attempting to perform cell selection with the same radio access technology as the second cell and, as a result, selecting a cell with the same radio access technology as the second cell. The method further includes storing, in the first report, at least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell.

Description

Related Applications

[0001] This application claims the benefit of provisional patent application serial number 63 / 400325 filed on August 23, 2022, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0002] The present disclosure relates to cellular communication systems, and more particularly to fault reporting in cellular communication systems. Background Art Voice fallback from NR to LTE

[0003] In the 3rd Generation Partnership Project (3GPP), during the call establishment process, voice fallback from New Radio (NR) to Long Term Evolution (LTE) is used to transfer the user equipment (UE) from NR to LTE. It enables the UE to utilize all NR functionality except voice options when 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 services, the UE and the Next Generation (NG) Radio Access Network (RAN) (i.e., NG-RAN) may support a mechanism to direct or redirect the UE from the NG-RAN towards the Evolved Universal Terrestrial Radio Access (E-UTRA) connected to the Fifth Generation Core (5GC) (referred to as Radio Access Technology (RAT) Fallback) or towards the Evolved Packet System (EPS) (referred to as Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system fallback connected to the Evolved Packet Core (EPC)). During the UE registration process, the serving Access and Mobility Management Function (AMF) informs the UE whether IMS voice over packet switched (PS) sessions is supported. If a request to establish a Quality of Service (QoS) flow for IMS Voice arrives at the NG-RAN, the NG-RAN responds to indicate that the establishment request is rejected and the NG-RAN may trigger one of the following procedures depending on UE capabilities, N26 availability, network configuration and radio conditions: Redirect to EPS; ·Switch process to EPS; Redirect to E-UTRA connected to 5GC; or Switch to E-UTRA connected to 5GC.

[0004] Further details can be found in 3GPP Technical Specification (TS) 23.501 V17.4.0.

[0005] Figure 1 Describes the EPS fallback procedure for IMS voice. Figure 1A detailed description can be found in Section 4.13.6.1 of 3GPP TS 23.502 V17.4.0 [2]. Self-Organizing Network (SON) in 3GPP

[0006] Self-organizing Network (SON) is an automation technology designed to make the planning, configuration, management, optimization and repair of mobile radio access networks simpler and faster. SON functionality and behavior have been defined and specified in generally accepted mobile industry recommendations proposed by organizations such as 3GPP and Next Generation Mobile Networks (NGMN).

[0007] In 3GPP, the processes within a SON area are classified into a self-configuration process and a self-optimization process. The self-configuration process is a process of configuring a newly deployed node through an automatic installation process to obtain the basic configuration required for system operation. This process works in a pre-operational state. The pre-operational state is understood as a state from when a base station (e.g., an evolved Node B (eNB) for LTE / E-UTRA) is powered on and has backbone connectivity until the radio frequency (RF) transmitter is turned on.

[0008] Figure 2 is a reproduction of Figure 22.1-1 of 3GPP TS 36.300 and shows the derivative of the self-configuration / self-optimization functionality. Figure 2 As shown in , the self-configuration process covers functions handled in the pre-operational state, such as: Basic settings; and Initial radio configuration.

[0009] The self-optimization process is defined as a process in which the network is automatically tuned using UE and access node measurements and performance measurements. This process works in an operational state. An operational state is understood as a state in which an RF interface is additionally turned on.

[0010] like Figure 2 As described in , the self-optimization process covers functions handled in the operational state, such as: Optimization / adaptation.

[0011] In LTE, support for self-configuration and self-optimization is specified, as described in 3GPP TS 36.300 Section 22.2, 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.

[0012] In NR, support for self-configuration and self-optimization is also specified, starting with self-configuration features such as dynamic configuration, Automatic Neighbor Relation (ANR) in Rel-15, as described in 3GPP TS 38.300 Section 15. In NR Rel-16, more SON features are being specified, including self-optimization features such as Mobility Robustness Optimization (MRO). Mobility Robustness Optimization (MRO) in 3GPP

[0013] Seamless handover is a key feature of 3GPP technology. Successful handover ensures that the UE moves around in the coverage area of ​​different cells without causing too much interruption in data transmission. However, there will be scenarios where the network fails to handover the UE to the 'correct' neighboring cell in time, and in such scenarios the UE will declare a Radio Link Failure (RLF) or Handover Failure (HOF).

[0014] Once HOF and RLF occur, the UE can take autonomous actions, i.e., try to select a cell and initiate a re-establishment procedure so that the UE tries to return as soon as possible so that it can be reached again. RLF will cause a poor user experience because the UE declares RLF only when it realizes that no reliable communication channel (radio link) is available between itself and the network. In addition, re-establishing the connection requires signaling (random access procedure, radio resource control (RRC) re-establishment request, RRC re-establishment, RRC re-establishment complete, RRC re-configuration, and RRC re-configuration complete) with the newly selected cell and adds some delay until the UE can exchange data with the network again.

[0015] According to the 3GPP specification (3GPP TS 36.331), the possible cause of a radio link failure may be one of the following: 1) Expiration of the radio link monitoring related timer T310; 2) Expiration of measurement report associated timer T312 (although a measurement report was sent when T310 was running, no handover command was received from the network during the duration of this timer); 3) Once the maximum number of Radio Link Control (RLC) retransmissions is reached; 4) Upon receiving a random access problem indication from the MAC entity.

[0016] Since RLF causes re-establishment (which degrades performance and user experience), it is in the interest of the network to understand the cause of the RLF and try to optimize mobility related parameters (e.g., triggering conditions for measurement reporting) to avoid future RLFs. Before standardizing MRO related reporting handling in the network, only the UE knew some information associated with how the radio quality looked at the time of RLF, what the actual reason for declaring RLF was, etc. In order for the network to identify the cause of the RLF, the network needs more information from the UE and from neighboring base stations.

[0017] As part of the MRO solution in LTE, in Rel-9 RAN2 work, a RLF reporting procedure was introduced in the RRC specification. That has impacted the RRC specification (TS 36.331) in the sense that it has been standardized that the UE will log the relevant information at the time of the RLF and then report to the target cell if the UE successfully connects (e.g. after re-establishment). That has also impacted the inter-gNodeB interface, i.e. the X2AP specification (3GPP TS 36.423), since an eNodeB receiving an RLF report may forward it to the eNodeB that has originated the failure.

[0018] For the RLF report generated by the UE, its content has been enhanced with more details in subsequent versions. The measurement results included in the measurement report based on the latest LTE RRC specification (i.e., V17.1.0) are: 1) Measurement quantities (reference signal received power (RSRP), reference signal received quality (RSRQ)) of the last serving cell (primary cell (PCell)). 2) Measurement quantities of neighboring cells in different frequencies of different RATs (Evolved Universal Terrestrial Radio Access (EUTRA), Universal Terrestrial Radio Access (UTRA), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE) Radio Access Network (GERAN), Code Division Multiple Access (CDMA) 2000). 3) A measurement quantity (Received Signal Strength Indicator (RSSI)) associated with a Wireless Local Area Network (WLAN) Access Point (AP). 4) Measurements associated with Bluetooth beacons (RSSI). 5) Position information, if available (including position coordinates and velocity). 6) The globally unique identifier of the last serving cell (if available), otherwise the physical cell identifier (PCI) and carrier frequency of the last serving cell. 7) Tracking area code of PCell. 8) The time that has passed since the last 'Switch Command' message was received. 9) The Cell Radio Network Temporary Identifier (C-RNTI) used in the previous serving cell. 10) Whether the UE has been configured with a data radio bearer (DRB) with a quality of service (QoS) class identifier (QCI) value of 1.

[0019] After declaring RLF, the RLF report is logged and included in VarRLF-Report, and once the UE selects a cell and succeeds on re-establishment, it includes an indication in the RRC Re-establishment Complete message that it has an RLF report available to let the target cell know of the availability. Then, upon receiving a UEInformationRequest message with flag "rlf-ReportReq-r9", the UE shall include the RLF report (stored in UE variable VarRLF-Report, as described above) in a UEInformationResponse message and send to the network.

[0020] Based on the RLF report from the UE and the knowledge about which cell the UE itself has reestablished, the original source cell can infer whether the RLF is due to a coverage hole or a handover-related parameter configuration. If the RLF is believed to be due to a handover-related parameter configuration, the original serving cell can further classify the handover-related failure into a too-early handover, too-late handover, or a handover to the wrong cell category. These handover failure categories are briefly explained below. 1) Whether a switching failure occurred due to a 'too late switching' situation a. When the original serving cell fails to send a handover command associated with a handover towards a specific target cell to the UE, and if the UE re-establishes itself in this target cell after RLF, the original serving cell may classify the handover failure as 'too late handover'. b. An example corrective action from the original serving cell could be to initiate the handover procedure towards the target cell a little earlier by reducing the Cell Individual Offset (CIO) towards this target cell, the CIO controls when the UE sends event-triggered measurement reports leading to the handover decision. 2) Whether a switching failure occurred due to a 'premature switching' situation a. When the original serving cell successfully sends a handover command associated with the handover to the UE, but the UE fails to perform a random access towards this target cell, the original serving cell may classify the handover failure as 'premature handover'. b. An example corrective action from the original serving cell could be to initiate the handover procedure towards the target cell a little later by increasing the CIO towards this target cell, which controls when the UE sends measurement reports triggered by the events leading to the handover decision. 3) Whether the handover failure occurred due to a 'handover to the wrong cell' situation a. When the original serving cell intends to perform a handover towards a specific target cell for this UE, but the UE declares RLF and re-establishes itself in a third cell, the original serving cell may classify the handover failure as 'handover to wrong cell'. b. The corrective action from the original serving cell may be to initiate a measurement reporting procedure which results in a later handover towards the target cell by decreasing the CIO towards the target cell, or by initiating an earlier handover towards the cell in which the UE has been reestablished by increasing the CIO towards the reestablished cell. Summary of the invention

[0021] Systems and methods for including information about a selected cell in a fault report are disclosed. In one embodiment, a method performed by a wireless terminal includes: receiving a configuration from a first cell to perform a handover to a second cell, the configuration including an indication indicating a voice fallback purpose. The method further includes: attempting to connect to the second cell using a mobility process; determining that a failure has occurred with respect to connecting to the second cell; and storing information associated with the failure in a first report. The method further includes: attempting to perform cell selection using the same radio access technology as the second cell; and as a result of attempting to perform cell selection, selecting a cell using the same radio access technology as the second cell. The method further includes: storing in the first report at least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell. In this manner, the wireless terminal can assist the network in understanding whether the selected cell is a suitable cell or an acceptable cell.

[0022] In one embodiment, a suitable cell is a cell on which a wireless terminal may camp, and an acceptable cell is a cell on which a wireless terminal may camp to obtain limited service.

[0023] In one embodiment, the first cell is a cell of a first radio access technology (RAT) and the second cell is a cell of a second RAT.

[0024] In one embodiment, the first cell is operated by a first network node and the second cell is operated by a second network node.

[0025] In one embodiment, the selected cell is operated by the same or a different network node as the network node operating the second cell.

[0026] In one embodiment, the failure is a handover failure. In another embodiment, the failure is a radio link failure (RLF) after a handover has been successfully completed.

[0027] In one embodiment, the selected cell is a suitable cell. In another embodiment, the selected cell is an acceptable cell.

[0028] In one embodiment, selecting a cell employing the same radio access technology as the second cell comprises: if there are no suitable cells, selecting an acceptable cell.

[0029] In one embodiment, selecting a cell that employs the same radio access technology as the second cell comprises selecting an acceptable cell even if a suitable cell exists.

[0030] In one embodiment, selecting a cell that employs the same radio access technology as the second cell comprises: selecting a cell from a public land mobile network (PLMN) that is different from a PLMN in which the wireless terminal performed a handover toward the second cell. In one embodiment, the method further comprises: storing in the first report an indication indicating a PLMN identity of the selected cell. In another embodiment, the method further comprises: storing in the first report an indication indicating whether the PLMN of the selected cell is the same as the PLMN of the second cell.

[0031] In one embodiment, the method further comprises: storing in the first report an indication indicating the PLMN identity of the selected cell.

[0032] In one embodiment, the method further comprises: storing in the first report an indication whether the PLMN of the selected cell is the same as the PLMN of the second cell.

[0033] In one embodiment, if the selected cell is not a suitable cell, the wireless terminal does not include the selected cell identification (ID) in the first report.

[0034] In one embodiment, the wireless terminal records and reports the amount of time from the time of failure to the time when the selected cell was selected.

[0035] In one embodiment, the wireless terminal records and reports information regarding whether the wireless terminal has detected one or more suitable cells and / or information regarding whether the wireless terminal has detected one or more acceptable cells.

[0036] In one embodiment, the method further comprises storing in the first report an indication indicating whether emergency services are enabled for the selected cell.

[0037] In one embodiment, the method further comprises: transmitting the first report to the network node.

[0038] Corresponding embodiments of the wireless terminal are also disclosed. In one embodiment, the wireless terminal is adapted to: receive a configuration from a first cell to perform a handover to a second cell, the configuration comprising an indication indicating a purpose for voice fallback. The wireless terminal is further adapted to: attempt to connect to the second cell using a mobility procedure; determine that a failure has occurred with respect to connecting to the second cell; and store information associated with the failure in a first report. The wireless terminal is further adapted to: attempt to perform cell selection using the same radio access technology as the second cell; and as a result of attempting to perform cell selection, select a cell using the same radio access technology as the second cell. The wireless terminal is further adapted to: store in the first report at least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell.

[0039] In one embodiment, a wireless terminal includes a communication interface and a processing circuit associated with the communication interface. The processing circuit is configured to cause the wireless terminal to receive a configuration from a first cell to perform a handover to a second cell, the configuration including an indication indicating a voice fallback purpose. The processing circuit is further configured to cause the wireless terminal to attempt to connect to the second cell using a mobility process, determine that a failure has occurred with respect to connecting to the second cell, and store information associated with the failure in a first report. The processing circuit is further configured to cause the wireless terminal to attempt to perform cell selection using the same radio access technology as the second cell, and as a result of attempting to perform cell selection, select a cell using the same radio access technology as the second cell. The processing circuit is further configured to cause the wireless terminal to store at least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell in the first report.

[0040] Embodiments of a method performed by a network node of a radio access network (RAN) for a cellular communication system are also disclosed. In one embodiment, the method performed by a network node of a RAN for a cellular communication system includes: receiving a fault report from a wireless terminal, the fault report including at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell. The method further includes: performing one or more actions based on the fault report.

[0041] Corresponding embodiments of a network node are also disclosed. In one embodiment, a network node for a RAN of a cellular communication system is adapted to: receive a fault report from a wireless terminal, the fault report comprising at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell. The network node is further adapted to: perform one or more actions based on the fault report.

[0042] In one embodiment, a network node of a RAN for a cellular communication system comprises a processing circuit configured to cause the network node to receive a fault report from a wireless terminal, the fault report comprising at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell. The processing circuit is further configured to cause the network node to perform one or more actions based on the fault report. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0044] Figure 1 Describes the Evolved Packet System (EPS) fallback procedure for Internet Protocol (IP) Multimedia Subsystem (IMS) Voice as defined in the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 23.502 V17.4.0;

[0045] Figure 2 is a reproduction of Figure 22.1-1 of 3GPP TS 36.300 and shows the derivative of the self-configuration / self-optimization functionality;

[0046] Figure 3 is a flow chart illustrating the operation of a wireless terminal (e.g., user equipment (UE)) according to one embodiment of the present disclosure;

[0047] Figure 4 illustrates an example of a communication system according to some embodiments;

[0048] Figure 5 illustrates a UE according to some embodiments;

[0049] Figure 6 illustrates a network node according to some embodiments;

[0050] Figure 7 is a block diagram of a host computer according to various aspects described herein, which may be Figure 4 An embodiment of a host;

[0051] Figure 8 is a block diagram illustrating a virtualization environment in which functionality implemented by some embodiments may be virtualized;

[0052] Fig. 9 A communication diagram showing a host communicating with a UE via a network node over a partially wireless connection according to some embodiments; and

[0053] Fig.10 is a flow chart illustrating the operation of a network node according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0054] The embodiments set forth below represent information that enables those skilled in the art to practice these embodiments, and illustrate the best mode for practicing these embodiments. Upon reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the application of these concepts not specifically proposed herein. It should be understood that these concepts and applications fall within the scope of the present disclosure.

[0055] There is currently a certain challenge. When a user equipment (UE) performs an inter-system voice fallback related handover, and if the handover fails, the UE first stores a radio link failure (RLF) report and then performs cell selection in Long Term Evolution (LTE) itself before falling back to New Radio (NR).

[0056] According to R2-2208617 ("Enhancements for Emergency Services Fallback Handling", 3GPP TSG-RAN WG2 Meeting #119 Electronic Version, August 17-August 29, 2022, and discussions in RAN2 Meeting #119), the UE may select a suitable cell or an acceptable cell. So far, the UE does not record the selected cell information, so this information is lost. It has been proposed to include the selected cell in the RLF report; however, the network is not able to understand whether the selected cell is a suitable cell or an acceptable cell. In addition, the UE may reselect a cell in another public land mobile network (PLMN), and such information is also not known to the network.

[0057] Note that as defined in 3GPP TS 38.304 V17.1.0, a suitable cell is a "cell on which the UE can camp". For NR cells, the criteria for a suitable cell are defined in clause 4.5 of 3GPP TS 38.304 V17.1.0, which states:

[0058] For UEs not operating in SNPN access mode, a cell is considered suitable if the following conditions are met: - the cell is part of a selected PLMN or a registered PLMN or a PLMN in a list of equivalent PLMNs, and for any of the PLMNs: - the PLMN-ID of this PLMN is broadcast by a cell without an associated CAG-ID and the CAG-only indication (TS 23.501

[10] ) for this PLMN in the UE is absent or false; - the allowed CAG list for this PLMN in the UE (TS 23.501

[10] ) includes the CAG-ID broadcast by the cells of this PLMN; - Satisfy the cell selection criteria, see clause 5.2.3.2.

[0059] According to the latest information provided by NAS: - The cell is not prohibited, see clause 5.3.1; - The cell is part of at least one TA that is not part of the list of "Tracking Areas Prohibited for Roaming" (TS 22.011

[18] ), which belongs to a PLMN that satisfies the first item above.

[0060] For a UE operating in SNPN access mode, a cell is considered suitable if the following conditions are met: - the cell is part of the UE's registered SNPN or selected SNPN; - meet the cell selection criteria, see clause 5.2.3.2;

[0061] According to the latest information provided by NAS: - The cell is not prohibited, see clause 5.3.1; - The cell is part of at least one TA which is not part of the list of "Tracking Areas Prohibited for Roaming" which belongs to the registered SNPN or the selected SNPN of the UE.

[0062] For E-UTRA, the criteria for suitable cells are found in 3GPP TS 36.304 V17.1.0.

[0063] In contrast, as defined in 3GPP TS 38.304 V17.1.0, an acceptable cell is "[a] cell that satisfies certain conditions as specified in 4.5". Clause 4.5 of 3GPP TS 38.304 V17.1.0 states:

[0064] An "acceptable cell" is a cell where the UE can camp to obtain limited services (initiating emergency calls and receiving ETWS and CMAS notifications). Such a cell should meet the following requirements, which are the minimum set of requirements to initiate emergency calls and receive ETWS and CMAS notifications in an NR network: - The cell is not prohibited, see clause 5.3.1; - Satisfy the cell selection criteria, see clause 5.2.3.2.

[0065] Certain aspects of the present disclosure and embodiments thereof may provide solutions to these or other challenges. An embodiment of a method performed by a UE is disclosed, wherein the UE includes at least one piece of information in an RLF report that indicates to a network node whether a first selected cell is a suitable cell or an acceptable cell. In addition, in one embodiment, the UE indicates whether a relevant service (e.g., an emergency call) is activated in the selected cell. In addition, in one embodiment, the UE records information about the PLMN in which the UE selected the first selected cell (e.g., in the case of NR to EUTRA fallback, the first selected cell is an Evolved Universal Terrestrial Radio Access (EUTRA) cell).

[0066] In one embodiment, the method performed by the UE includes one or more of the following steps: Receiving a configuration from a first network cell (which may be served by the first node, such as an NR source node) to perform a handover to a second network cell (which may be served by a second node, such as an LTE network node), the configuration including an indication indicating a voice fallback purpose. Try to connect to the second network node Failed to connect to the second network node Storing information associated with the fault in a first report (e.g., RLF report) Attempt to perform cell selection using the same radio access technology as the second network node and select a cell using the same radio access technology • Including in the first report (eg, RLF report) an indication whether the selected cell is a suitable cell or an acceptable cell. • Including in the first report (eg, RLF report) an indication whether emergency services are enabled for the selected cell. including (e.g. in the first report (e.g. RLF report)) an indication of the PLMN identity of the selected cell • Transmitting a first report (eg, a RLF report) to a network node.

[0067] Certain embodiments may provide one or more of the following (one or more) technical advantages. Based on embodiments of the methods disclosed herein, the UE may assist the network in understanding whether the selected cell is a suitable cell or an acceptable cell. In addition, in some embodiments, the UE indicates the PLMN identity of the selected cell, which may be used by a radio access network (RAN) node for future handovers.

[0068] Figure 3 1 is a flow chart showing the operation of a wireless terminal (e.g., a user equipment (UE) in the following description) according to an embodiment of the present disclosure. As shown in the figure, the steps of the process are as follows: Step 300: The UE receives a configuration from a first cell (which may be referred to as a source cell and may be, for example, an NR cell) to perform a handover to a second cell (which may be referred to as a target cell and may be, for example, an LTE cell), the configuration including an indication indicating a purpose of voice fallback. o In one embodiment, the first cell is associated with a first network node (eg, of a first RAT such as, for example, NR) and the second cell is associated with a second network node (eg, of a second RAT such as, for example, EUTRA) . • Step 302: The UE attempts to connect to the second cell using a mobility procedure (eg, a handover procedure, which may be referred to as a "reconfiguration with synchronization" procedure). • Step 304: The UE determines a failure with respect to connecting to the second cell (eg, determines that it has failed to connect to the second cell). o In one embodiment, the failure is a switching failure. o In another embodiment, the failure is a RLF after a successful completion of a handover. • Step 306: The UE stores information associated with the failure in a first report (eg, RLF report). Step 308: The UE attempts to perform cell selection using the same radio access technology as the second network node, and selects a cell using the same radio access technology as the second network node. o In one embodiment, the UE may select a suitable cell. o In another embodiment, if there is no suitable cell, the UE may select an acceptable cell. o In another embodiment, the UE may select an acceptable cell even if a suitable cell exists. o In yet another embodiment, the UE may select a cell from another PLMN that is different from the PLMN in which the UE performed a handover towards the second cell. • Step 310: The UE includes an indication in the first report, wherein the indication indicates whether the selected cell is a suitable cell or an acceptable cell. o In one embodiment, if the selected cell is not a suitable cell, the UE does not include the selected cell ID. o In another embodiment, the UE records and reports in the first report (eg, in the RLF report) the time from failure to the cell selection time. o In another embodiment, the UE records and reports information about whether the UE has detected one or more suitable cells and information about whether the UE has detected one or more acceptable cells. Step 312 (optional): The UE includes an indication of the PLMN identity of the selected cell in the first report. In one embodiment, the UE may include an indication indicating whether the selected PLMN is the same as the PLMN of the target cell where the handover is performed. • Step 314 (optional): The UE includes in the first report an indication whether emergency services are enabled for the selected cell. Step 316: The UE transmits a first report to the network node.

[0069] Fig.10 1 is a flow chart illustrating the operation of a network node according to an embodiment of the present disclosure. As shown, the network node receives a fault report (e.g., a HOF report or an RLF report) from a wireless terminal (e.g., a UE) including an indication that the selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell (step 1000). The network node may then perform one or more actions based on the fault report (e.g., forwarding the fault report to a network node serving the original source cell for analysis) (step 1002).

[0070] Figure 4 An example of a communication system 400 is shown in accordance with some embodiments.

[0071] In the example, the communication system 400 includes a telecommunications network 402, which includes an access network 404 such as a radio access network (RAN) and a core network 406 including one or more core network nodes 408. The access network 404 includes one or more access network nodes, such as network nodes 410A and 410B (one or more of which may be generally referred to as network nodes 410), or any other similar third generation partnership project (3GPP) access nodes or non-3GPP access points (APs). The network nodes 410 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 412A, 412B, 412C, and 412D (one or more of which may be generally referred to as UEs 412) to the core network 406 via one or more wireless connections.

[0072] Example wireless communications via wireless connections include: transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without using wires, cables, or other material conductors. In addition, in different embodiments, the communication system 400 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals (whether via a wired connection or a wireless connection). The communication system 400 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar types of systems.

[0073] UE 412 may be any of a variety of communication devices, including wireless devices that are arranged, configured and / or operable to wirelessly communicate with network node 410 and other communication devices. Similarly, network node 410 is arranged, capable, configured and / or operable to communicate directly or indirectly with UE 412 and / or with other network nodes or devices in telecommunication network 402 to enable and / or provide network access (such as wireless network access) and / or perform other functions (such as management in telecommunication network 402).

[0074] In the depicted example, the core network 406 connects the network node 410 to one or more hosts, such as the host 416. These connections may be direct or indirect via one or more intermediate networks or devices. In other examples, the network node may be directly coupled to the host. The core network 406 includes one or more core network nodes (e.g., core network node 408) composed of hardware and software components. The features of these components may be substantially similar to those described with respect to the UE, network nodes, and / or hosts, so that their descriptions are generally applicable to the corresponding components of the core network node 408. The example core network node includes the functions of one or more of a mobile switching center (MSC), a mobility management entity (MME), a home subscriber server (HSS), an access and mobility management function (AMF), a session management function (SMF), an authentication server function (AUSF), a subscription identifier unhiding function (SIDF), a unified data management (UDM), a security edge protection proxy (SEPP), a network open function (NEF), and / or a user plane function (UPF).

[0075] The host 416 may be owned or controlled by a service provider that is different from the operator or provider of the access network 404 and / or the telecommunications network 402, and may be operated by or on behalf of the service provider. The host 416 may host various applications to provide one or more services. Examples of such applications include live and pre-recorded audio / video content, data collection services (such as retrieving and compiling data about various environmental conditions detected by multiple UEs), analysis functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for alarm and monitoring centers, or any other such functions performed by a server.

[0076] Overall, Figure 4The communication system 400 can enable connectivity between UEs, network nodes, and hosts. In this sense, the communication system 400 can be configured to operate according to predefined rules or procedures such as specific standards, including but 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 (2G, 3G, 4G, or 5G) standards or any applicable future generation standards (e.g., sixth generation (6G)); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard (WiFi); and / or any other suitable wireless communication standards, such as 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).

[0077] In some examples, the telecommunication network 402 is a cellular network implementing 3GPP standardized features. Therefore, the telecommunication network 402 can support network slicing to provide different logical networks to different devices connected to the telecommunication network 402. For example, the telecommunication network 402 can provide ultra-reliable low-latency communication (URLLC) services to some UEs, enhanced mobile broadband (eMBB) services to other UEs, and / or massive machine type communication (mMTC) / massive Internet of Things (IoT) services to yet other UEs.

[0078] In some examples, UE 412 is configured to transmit and / or receive information without direct human interaction. For example, the UE may be designed to transmit information to access network 404 on a predetermined schedule when triggered by an internal or external event, or in response to a request from access network 404. In addition, the UE may be configured to operate in a single radio access technology (RAT) or in a multi-RAT or multi-standard mode. For example, the UE may operate using any one or a combination of WiFi, new air interface (NR) and LTE, i.e., configured for multi-radio dual connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR-Dual Connectivity (EN-DC).

[0079] In an example, the hub 414 communicates with the access network 404 to facilitate indirect communication between one or more UEs (e.g., UE 412C and / or 412D) and a network node (e.g., network node 410B). In some examples, the hub 414 can be any of a controller, a router, a content source and an analysis device, or other communication devices described herein with respect to the UE. For example, the hub 414 can be a broadband router that enables the UE to access the core network 406. As another example, the hub 414 can be a controller that sends commands or instructions to one or more actuators in the UE. The commands or instructions can be received from the UE, the network node 410, or received through an executable code, a script, a process, or other instructions in the hub 414. As another example, the hub 414 can be a data collector that acts as a temporary storage device for UE data, and in some embodiments, analysis or other processing of the data can be performed. As another example, the hub 414 can be a content source. For example, for a UE that is a virtual reality (VR) headset, display, speaker, or other media delivery device, the hub 414 can retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, and then the hub 414 provides it to the UE directly and / or after adding additional local content after performing local processing. In yet another example, particularly where one or more of the UEs are low-energy IoT devices, the hub 414 acts as a proxy server or orchestrator for the UE.

[0080] Hub 414 may have a constant / persistent or intermittent connection to network node 410B. Hub 414 may also allow different communication schemes and / or scheduling between hub 414 and UE (e.g., UE 412C and / or 412D) and between hub 414 and core network 406. In other examples, hub 414 is connected to core network 406 and / or one or more UEs via a wired connection. In addition, hub 414 may be configured to be connected to a machine-to-machine (M2M) service provider and / or to another UE via a direct connection via access network 404. In some scenarios, UE may establish a wireless connection with network node 410, while still being connected via hub 414 via a wired or wireless connection. In some embodiments, hub 414 may be a dedicated hub, that is, a hub whose main function is to route communications from UE to network node 410B or from network node 410B to UE. In other embodiments, hub 414 may be a non-dedicated hub - ie, a device operable to route communications between UEs and network node 410B, but otherwise capable of operating as a communications start and / or end point for certain data channels.

[0081] Figure 5UE 500 according to some embodiments is shown. As used herein, UE refers to a device capable of, configured, arranged and / or operable to wirelessly communicate with a network node and / or other UEs. Examples of UEs 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 cameras, game consoles or devices, music storage devices, playback appliances, wearable terminal devices, wireless endpoints, mobile stations, tablets, laptop computers, laptop embedded devices (LEEs), laptop mounted devices (LMEs), smart devices, wireless client equipment (CPEs), vehicle mounted or vehicle embedded / integrated wireless devices, etc. Other examples include any UE identified by 3GPP, including narrowband Internet of Things (NB-IoT) UEs, machine type communications (MTC) UEs, and / or enhanced MTC (eMTC) UEs.

[0082] The UE may support device-to-device (D2D) communications, for example, by implementing 3GPP standards for direct link communications, dedicated short range communications (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, the UE may not necessarily have a user in the sense of a human user who owns and / or operates the associated device. Instead, the UE may represent a device that is intended to be sold to or operated by a human user, but may not or may not initially be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, the UE may represent a device that is not intended to be sold to or operated by an end user, but may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0083] UE 500 includes processing circuitry 502, which is operatively coupled to input / output interface 506, power supply 508, memory 510, communication interface 512, and / or any other components or any combination thereof via bus 504. Some UEs may utilize Figure 5 All components shown in the UE or a subset of these components. The degree of integration between components may vary from one UE to another UE. In addition, some UEs may include multiple instances of components, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0084] The processing circuit 502 is configured to process instructions and data, and may be configured to implement any sequential state machine that is operable to execute instructions stored in the memory 510 as a machine-readable computer program. The processing circuit 502 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 microprocessors or digital signal processors (DSPs), together with appropriate software; or any combination of the above. For example, the processing circuit 502 may include multiple central processing units (CPUs).

[0085] In this example, the input / output interface 506 may be configured to provide one or more interfaces to an input device, an output device, or one or more input and / or output devices. Examples of output devices include speakers, sound cards, video cards, displays, monitors, printers, actuators, transmitters, smart cards, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 500. Examples of input devices include touch-sensitive displays or presence-sensitive displays, cameras (e.g., digital cameras, digital video cameras, web cameras, etc.), microphones, sensors, mice, trackballs, directional pads, trackpads, rollers, smart cards, and the like. A presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. The sensor may be, for example, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, and the like, or any combination thereof. An output device may use an interface port of the same type as an input device. For example, a universal serial bus (USB) port may be used to provide input devices and output devices.

[0086] In some embodiments, the power supply 508 is configured as a battery or battery pack. Other types of power supplies may be used, such as an external power source (e.g., an electrical socket), a photovoltaic device, or a power battery. The power supply 508 may further include a power circuit for delivering power from the power supply 508 itself and / or an external power source to various parts of the UE 500 via an input circuit or interface such as a power cable. The delivered power may be used, for example, to charge the power supply 508. The power circuit may perform any formatting, conversion, or other modification on the power from the power supply 508 to make the power suitable for the corresponding components of the UE 500 to which the power is supplied.

[0087] The memory 510 may be or be configured to include a memory such as a random access memory (RAM), a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically EPROM (EEPROM), a magnetic disk, an optical disk, a hard disk, a removable cartridge, a flash drive, etc. In one example, the memory 510 includes: one or more application programs 514, such as an operating system, a web browser application, a widget, a gadget engine, or other application; and corresponding data 516. The memory 510 may store any one of a variety of operating systems or a combination of operating systems for use by the UE 500.

[0088] The memory 510 may be configured to include multiple physical drive units, such as a redundant array of independent disks (RAID), flash memory, USB flash drive, external hard drive, thumb drive, pen drive, key drive, high density digital versatile disk (HD-DVD) optical drive, internal hard drive, Blu-ray optical drive, holographic digital data storage (HDDS) optical drive, external mini dual in-line memory module (DIMM), synchronous dynamic RAM (SDRAM), external micro-DIMM SDRAM, smart card memory (such as a tamper-proof 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 an Internet Protocol Multimedia Service Identity Module (ISIM)), other memories, or any combination thereof. The UICC may be, for example, an embedded UICC (eUICC), an integrated UICC (iUICC), or a removable UICC commonly referred to as a 'SIM card'. The memory 510 may allow the UE 500 to access instructions, applications, etc. stored on a temporary or non-temporary memory medium to offload data or upload data. An article of manufacture, such as an article of manufacture utilizing a communication system, may be tangibly embodied as or in memory 510, which may be or may include a device-readable storage medium.

[0089] The processing circuit 502 may be configured to communicate with an access network or other network using a communication interface 512. The communication interface 512 may include one or more communication subsystems and may include or be communicatively coupled to an antenna 522. The communication interface 512 may include one or more transceivers for communicating, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 518 and / or a receiver 520 suitable for providing network communications (e.g., optical, electrical, frequency allocation, etc.). In addition, the transmitter 518 and the receiver 520 may be coupled to one or more antennas (e.g., antenna 522) and may share circuit components, software or firmware, or may be implemented separately as an alternative.

[0090] In the illustrated embodiment, the communication functionality of the communication interface 512 may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communication such as Bluetooth, NFC, location-based communication such as using a global positioning system (GPS) to determine location, another similar communication functionality, or any combination thereof. The communication may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, code division multiple 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), fast user datagram protocol Internet connection (QUIC), hypertext transfer protocol (HTTP), etc.

[0091] Regardless of the type of sensor, the UE may provide an output of the data captured by its sensor through its communication interface 512 or via a wireless connection to a network node. The data captured by a sensor of a UE may be delivered to a network node via another UE via a wireless connection. The output may be periodic (e.g., every 15 minutes if it reports a sensed temperature), random (e.g., to load balance reports from several sensors), in response to a trigger event (e.g., sending an alarm when moisture is detected), in response to a request (e.g., a user-initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0092] As another example, the UE includes an actuator, motor, or switch associated with a communication interface that is configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input, the state of the actuator, motor, or switch may change. For example, the UE may include a motor that adjusts a control surface or rotor of a drone in flight based on the received input, or a robotic arm that performs a medical procedure based on the received input.

[0093] When a UE takes the form of an IoT device, it can be a device used in one or more application areas, including but not limited to urban wearable technology, extended industrial applications, and healthcare. Non-limiting examples of such IoT devices are devices that are or are embedded in connected refrigerators or freezers, televisions, connected lighting devices, electric meters, robotic vacuum cleaners, voice-controlled smart speakers, home security cameras, motion detectors, thermostats, smoke detectors, door / window sensors, overflow / moisture sensors, electrical door locks, connected doorbells, air conditioning systems such as heat pumps, autonomous vehicles, surveillance systems, weather monitoring devices, vehicle parking monitoring devices, electric vehicle charging stations, smart watches, fitness trackers, head-mounted displays for augmented reality (AR) or VR, wearable devices for tactile enhancement or sensory enhancement, sprinklers, animal or item tracking devices, sensors for monitoring plants or animals, industrial robots, unmanned aerial vehicles (UAVs), and any kind of medical device (such as a heart rate monitor or a remotely controlled surgical robot). A UE in the form of an IoT device includes circuitry and / or software depending on the intended application of the IoT device, plus information about Figure 5 Other components described for UE 500 shown in .

[0094] As another specific example, in an IoT scenario, a UE may represent a machine or other device that performs monitoring and / or measurement and transmits the results of such monitoring and / or measurement to another UE and / or a network node. In this case, the UE may be an M2M device, which may be referred to as an MTC device in the 3GPP context. As a specific example, a UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle such as a car, bus, truck, ship, airplane, or other device capable of monitoring and / or reporting its operating status or other functions associated with its operation.

[0095] In practice, any number of UEs may be used together for a single use case. For example, a first UE may be a drone or may be integrated into a drone, and may provide speed information of the drone (obtained by a speed sensor) to a second UE that is a remote controller operating the drone. When a user makes a change 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 speed of the drone. The first and / or second UE may also include more than one of the functionalities described above. For example, the UE may include a sensor and an actuator, and handle the communication of data for both the speed sensor and the actuator.

[0096] Figure 6A network node 600 according to some embodiments is shown. As used herein, a network node refers to a device capable of, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or devices in a telecommunications 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)).

[0097] BSs may be classified based on the amount of coverage they provide (or in other words, their transmit power level), and therefore, depending on the amount of coverage provided, they 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 that controls a relay. A network node may also include one or more (or all) parts of a distributed radio BS, such as a centralized digital unit and / or a remote radio unit (RRU), sometimes referred to as a remote radio head (RRH). Such an RRU 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).

[0098] Other examples of network nodes include a multi-transmission point (multi-TRP) 5G access node, a multi-standard radio (MSR) device (such as an MSR BS), a network controller (such as a radio network controller (RNC) or a BS controller (BSC)), a base transceiver station (BTS), a transmission point, a transmission node, a multi-cell / multicast coordination entity (MCE), an operation and maintenance (O&M) node, an operation support system (OSS) node, a self-organizing network (SON) node, a positioning node (e.g., an evolved serving mobile location center (E-SMLC)), and / or minimization of drive tests (MDT).

[0099] The network node 600 includes a processing circuit 602, a memory 604, a communication interface 606, and a power supply 608. The network node 600 may be composed of multiple physically separated components (e.g., a node B component and an RNC component, or a BTS component and a BSC component, etc.), each of which may have its own corresponding components. In certain scenarios where the network node 600 includes multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared between several network nodes. For example, a single RNC may control multiple node Bs. In such scenarios, each unique node B and RNC pair may be considered as a single separate network node in some instances. In some embodiments, the network node 600 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memories 604 for different RATs), and some components may be reused (e.g., antennas 610 may be shared by different RATs). The network node 600 may also include multiple sets of various illustrated components for different wireless technologies, such as GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies, integrated into the network node 600. These wireless technologies may be integrated into the same or different chips or chipsets and other components within the network node 600.

[0100] The processing circuit 602 may include a combination of one or more of the following: a microprocessor, a controller, a microcontroller, a CPU, a DSP, an ASIC, an FPGA, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic that can operate to provide network node 600 functionality alone or in combination with other network node 600 components (such as memory 604).

[0101] In some embodiments, processing circuitry 602 includes a system on a chip (SOC). In some embodiments, processing circuitry 602 includes one or more of radio frequency (RF) transceiver circuitry 612 and baseband processing circuitry 614. In some embodiments, RF transceiver circuitry 612 and baseband processing circuitry 614 may be on separate chips (or chipsets), boards, or units (such as a radio unit and a digital unit). In alternative embodiments, part or all of RF transceiver circuitry 612 and baseband processing circuitry 614 may be on the same chip or chipset, board, or unit.

[0102] Memory 604 may include any form of volatile or non-volatile computer-readable memory, including, but not limited to: a persistent storage device, solid-state memory, remotely mounted memory, magnetic media, optical media, RAM, ROM, mass storage media (e.g., a hard disk), removable storage media (e.g., 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 device that stores information, data and / or instructions that can be used by processing circuit 602. Memory 604 may store any suitable instructions, data or information, including computer programs, software, applications (including one or more of logic, rules, codes, tables, etc.), and / or other instructions that can be executed by processing circuit 602 and utilized by network node 600. Memory 604 may be used to store any calculations performed by processing circuit 602 and / or any data received via communication interface 606. In some embodiments, processing circuit 602 and memory 604 are integrated.

[0103] The communication interface 606 is used for wired or wireless communication of signaling and / or data between network nodes, access networks and / or UEs. As shown, the communication interface 606 includes (one or more) ports / (one or more) terminals 616, for example, to send data to the network and receive data from the network via a wired connection. The communication interface 606 also includes a radio front-end circuit 618, which can be coupled to the antenna 610, or as a part of the antenna 610 in some embodiments. The radio front-end circuit 618 includes a filter 620 and an amplifier 622. The radio front-end circuit 618 can be connected to the antenna 610 and the processing circuit 602. The radio front-end circuit 618 can be configured to adjust the signal transmitted between the antenna 610 and the processing circuit 602. The radio front-end circuit 618 can receive digital data to be sent to other network nodes or UEs via a wireless connection. The radio front-end circuit 618 can use a combination of a filter 620 and / or an amplifier 622 to convert the digital data into a radio signal with appropriate channel and bandwidth parameters. Then, the radio signal can be transmitted via the antenna 610. Similarly, when receiving data, antenna 610 may collect radio signals, which may then be converted into digital data by radio front end circuit 618. The digital data may be passed to processing circuit 602. In other embodiments, communication interface 606 may include different components and / or different combinations of components.

[0104] In certain alternative embodiments, the network node 600 does not include a separate radio front end circuit 618; instead, the processing circuit 602 includes the radio front end circuit and is connected to the antenna 610. Similarly, in some embodiments, all or part of the RF transceiver circuit 612 is part of the communication interface 606. In still other embodiments, the communication interface 606 includes one or more ports or terminals 616, the radio front end circuit 618, and the RF transceiver circuit 612 as part of a radio unit (not shown), and the communication interface 606 communicates with the baseband processing circuit 614 as part of a digital unit (not shown).

[0105] Antenna 610 may include one or more antennas or antenna arrays configured to send and / or receive wireless signals. Antenna 610 may be coupled to radio front end circuit 618 and may be any type of antenna capable of wirelessly transmitting and receiving data and / or signals. In some embodiments, antenna 610 is separate from network node 600 and may be connected to network node 600 via an interface or port.

[0106] The antenna 610, the communication interface 606, and / or the processing circuit 602 may be configured to perform any receiving operation and / or certain obtaining operations described herein as being performed by the network node 600. Any information, data, and / or signal may be received from a UE, another network node, and / or any other network device. Similarly, the antenna 610, the communication interface 606, and / or the processing circuit 602 may be configured to perform any transmitting operation described herein as being performed by the network node 600. Any information, data, and / or signal may be transmitted to a UE, another network node, and / or any other network device.

[0107] The power supply 608 provides power to the various components of the network node 600 in a form suitable for the respective components (e.g., at the voltage and current levels required by each respective component). The power supply 608 may further include or be coupled to a power management circuit to power the components of the network node 600 for performing the functionality described herein. For example, the network node 600 may be connectable to an external power source (e.g., an electrical grid or an electrical outlet) via an input circuit or interface (such as a cable), whereby the external power source provides power to the power circuit of the power supply 608. As a further example, the power supply 608 may include a source of power in the form of a battery or battery pack connected to or integrated in the power circuit. If the external power source fails, the battery may provide backup power.

[0108] Apart from Figure 6Embodiments of network node 600 may include additional components in addition to those components shown in Figure 6 to provide certain aspects of the functionality of the network node, including any of the functionality described herein and / or any functionality required to support the subject matter described herein. For example, network node 600 may include a user interface device to allow information to be input into network node 600 and to allow information to be output from network node 600. This may allow a user to perform diagnostic, maintenance, repair, and other management functions for network node 600.

[0109] Figure 7 is a block diagram of a host 700 according to various aspects described herein, which may be Figure 4 4. As used herein, host 700 may be or include various combinations of hardware and / or software, including processing resources in a standalone server, blade server, cloud-implemented server, distributed server, virtual machine, container, or server farm. Host 700 may provide one or more services to one or more UEs.

[0110] Host 700 includes processing circuitry 702, which is operatively coupled to input / output interface 706, network interface 708, power supply 710, and memory 712 via bus 704. Other components may be included in other embodiments. The features of these components may be substantially similar to those described with respect to previous figures (such as Figure 5 and Figure 6 ) so that its description is generally applicable to the corresponding components of the host 700.

[0111] The memory 712 may include one or more computer programs, including one or more host applications 714 and data 716, which may include user data, such as data generated by the UE for the host 700 or data generated by the host 700 for the UE. An embodiment of the host 700 may utilize only a subset of the components shown or utilize all of the components shown. The host application 714 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.711), including transcoding for multiple different categories, types or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, and heads-up display systems). The host application 714 may also provide user authentication and permission checks, and may periodically report health status, routing, and content availability to a central node (such as a device in a core network or on its edge). Thus, the host 700 can select and / or indicate different hosts for over-the-top (OTT) services for the UE. The host application 714 can support various protocols, such as 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.

[0112] Figure 8 800 is a block diagram showing a virtualized environment 800 in which the functions implemented in some embodiments can be virtualized. In this context, virtualization means creating a virtual version of a device or apparatus, which may include virtualizing a hardware platform, storage device, and networking resources. As used herein, virtualization can be applied to any device or component thereof described herein, and involves an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs), which are implemented in one or more virtual environments 800 taken over by one or more hardware nodes in a hardware computing device such as a network node, UE, core network node, or host. In addition, in embodiments in which a virtual node does not require radio connectivity (e.g., a core network node or host), the node may be fully virtualized.

[0113] Application 802 (which may alternatively be referred to as a software instance, a virtual appliance, a network function, a virtual node, a virtual network function, etc.) runs in virtualization environment 700 to implement some features, functions and / or benefits of some embodiments disclosed herein.

[0114] The hardware 804 includes processing circuitry, memory storing software and / or instructions executable by the hardware processing circuitry, and / or other hardware devices as described herein, such as network interfaces, input / output interfaces, etc. The software may be executed by the processing circuitry to instantiate one or more virtualization layers 806 (also referred to as hypervisors or VM monitors (VMMs)), provide VMs 808A and 808B (one or more of which may be generally referred to as VMs 808), and / or perform any of the functions, features, and / or benefits described with respect to some embodiments described herein. The virtualization layer 806 may present a virtual operating platform that appears to be networked hardware to the VMs 808.

[0115] VM 808 includes virtual processing, virtual memory, virtual networking or interfaces, and virtual storage, and may be run by a corresponding virtualization layer 806. Different embodiments of instances of virtual appliances 802 may be implemented on one or more of VMs 808, and these implementations may be performed in different ways. In some contexts, virtualization of hardware is referred to as network function virtualization (NFV). NFV may be used to integrate many network device types onto industry standard high-volume server hardware, physical switches, and physical storage devices, which may be located in data centers as well as client devices.

[0116] In the context of NFV, VM 808 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each VM in VM 808 and the portion of hardware 804 that executes the VM (whether it is hardware dedicated to the VM and / or hardware shared by the VM with other VMs in VM 808) form a separate virtual network element. Still in the context of NFV, a virtual network function is responsible for handling specific network functions running in one or more VMs 808 on hardware 804 and corresponds to application 802.

[0117] The hardware 804 may be implemented in a standalone network node with general or specialized components. The hardware 804 may implement some functions via virtualization. Alternatively, the hardware 804 may be part of a larger hardware cluster (e.g., such as in a data center or CPE) in which many hardware nodes work together and are managed via management and orchestration 810, which, among other things, oversees the lifecycle management of the application 802. In some embodiments, the hardware 804 is coupled to one or more radio units, each of which includes one or more receivers and one or more transmitters that may be coupled to one or more antennas. The radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces, and may be used in combination with virtual components to provide a virtual node with radio capabilities, such as a RAN or BS. In some embodiments, some signaling may be provided by using a control system 812, which may alternatively be used for communication between hardware nodes and radio units.

[0118] Fig. 9 A communication diagram is shown in which a host 902 communicates with a UE 906 via a network node 904 over a partially wireless connection according to some embodiments. Fig. 9 Describe the UE discussed in the previous paragraph (such as Figure 4 UE 412A and / or Figure 5 UE 500), network nodes (such as Figure 4 The network node 410A and / or Figure 6 network nodes 600) and hosts (such as Figure 4 Host 416 and / or Figure 7 An example implementation of a host 700 according to various embodiments.

[0119] Similar to the host 700, an embodiment of the host 902 includes hardware, such as a communication interface, a processing circuit, and a memory. The host 902 also includes software that is stored in or accessible by the host 902 and can be executed by the processing circuit. The software includes a host application that can be operable to provide services to a remote user, such as a UE 906 connected via an OTT connection 950 extending between the UE 906 and the host 902. During the provision of services to the remote user, the host application can provide user data transmitted using the OTT connection 950.

[0120] The network node 904 includes hardware that enables it to communicate with the host 902 and the UE 906 via a connection 960. The connection 960 may be direct or through a core network (e.g. Figure 4The core network 406 of the present invention) and / or one or more other intermediate networks, such as one or more public, proprietary or managed networks. For example, the intermediate network can be a backbone network or the Internet.

[0121] UE 906 includes hardware and software, the software is stored in UE 906 or accessible by UE 906, and can be executed by the processing circuit of UE. The software includes a client application, such as a World Wide Web browser or an operator-specific "app", which can be operable to provide services to human or non-human users via UE 906 with the support of host 902. In the host 902, the executed host application can communicate with the executed client application via an OTT connection 950 terminated at UE 906 and host 902. During the provision of services to the user, the client application of the UE can receive request data from the host application of the host, and provide user data in response to the request data. The OTT connection 950 can transmit both request data and user data. The client application of the UE can interact with the user to generate user data, which it provides to the host application via the OTT connection 950.

[0122] The OTT connection 950 may extend via a connection 960 between the host 902 and the network node 904 and via a wireless connection 970 between the network node 904 and the UE 906 to provide a connection between the host 902 and the UE 906. The connection 960 and the wireless connection 970 over which the OTT connection 950 may be provided have been drawn abstractly to illustrate communication between the host 902 and the UE 906 via the network node 904 without explicit reference to any intermediate devices and the exact routing of messages via these devices.

[0123] As an example of transmitting data via the OTT connection 950, in step 908, the host 902 provides user data, which can be performed by executing a host application. In some embodiments, the user data is associated with a specific human user interacting with the UE 906. In other embodiments, the user data is associated with the UE 906, which shares data with the host 902 without explicit human interaction. In step 910, the host 902 initiates a transmission carrying the user data to the UE 906. The host 902 may initiate the transmission in response to a request issued by the UE 906. The request may be caused by human interaction with the UE 906, or by the operation of a client application executed on the UE 906. According to the teachings of the embodiments described throughout the present disclosure, the transmission may pass through the network node 904. Therefore, in step 912, according to the teachings of the embodiments described throughout the present disclosure, the network node 904 transmits to the UE 906 the user data that was carried in the transmission that the host 902 initiated. In step 914 , the UE 906 receives the user data carried in the transmission, which may be performed by a client application executing on the UE 906 associated with a host application executed by the host 902 .

[0124] In some examples, the UE 906 executes a client application, which provides user data to the host 902. The user data may be provided in reaction or response to data received from the host 902. Therefore, in step 916, the UE 906 may provide the user data, which may be performed by executing the client application. During the provision of the user data, the client application may further consider the user input received from the user via the input / output interface of the UE 906. Regardless of the specific manner of providing the user data, in step 918, the UE 906 initiates the transmission of the user data to the host 902 via the network node 904. In step 920, in accordance with the teachings of the embodiments described throughout the present disclosure, the network node 904 receives the user data from the UE 906 and initiates the transmission of the received user data to the host 902. In step 922, the host 902 receives the user data carried in the transmission initiated by the UE 906.

[0125] One or more of the various embodiments improve the performance of OTT services provided to UE 906 using OTT connection 950 (where wireless connection 970 forms the last leg).

[0126] In an example scenario, plant status information may be collected and analyzed by the host 902. As another example, the host 902 may process audio and video data that may have been retrieved from the UE for use in creating a map. As another example, the host 902 may collect and analyze real-time data to help control traffic congestion (e.g., control traffic lights). As another example, the host 902 may store surveillance videos uploaded by the UE. As another example, the host 902 may store media content such as video, audio, VR, or AR that it can broadcast, multicast, or unicast to the UE, or control access to media content. As other examples, the host 902 may be used for energy pricing, remote control of non-time-critical electrical loads to balance power generation needs, location services, presentation services (such as compiling charts based on data collected from remote devices, etc.), or any other function of collecting, retrieving, storing, analyzing, and / or transmitting data.

[0127] In some examples, a measurement process may be provided for the purpose of monitoring data rate, latency, and other factors to be improved by one or more embodiments. In order to reconfigure the OTT connection 950 between the host 902 and the UE 906 in response to changes in the measurement results, there may also be optional network functionality. The measurement process and / or the network functionality for reconfiguring the OTT connection 950 may be implemented in the software and hardware of the host 902 and / or the UE 906. In some embodiments, sensors (not shown) may be deployed in other devices or in association with other devices through which the OTT connection 950 passes; the sensors may participate in the measurement process by supplying the values ​​of the monitoring quantities exemplified above or by supplying the values ​​of other physical quantities (based on these values, the software may calculate or estimate the monitoring quantities). The reconfiguration of the OTT connection 950 may include message formats, retransmission settings, preferred routing selection, etc.; the reconfiguration does not require direct changes to the operation of the network node 904. Such processes and functionality may be known and practiced in the art. In certain embodiments, the measurement may involve proprietary UE signaling, which facilitates the host 902 to measure throughput, propagation time, latency, etc. The measurements can be achieved because the software causes messages (particularly empty or 'dummy' messages) to be transmitted using the OTT connection 950 while monitoring propagation times, errors etc.

[0128] Although the computing devices (e.g., UE, network node, host) described herein may include a combination of the hardware components shown, other embodiments may include computing devices with different combinations of components. It is to be understood that these computing devices may include any appropriate combination of hardware and / or software required to perform the tasks, features, functions and methods disclosed herein. The determination, calculation, acquisition or similar operations described herein may be performed by a processing circuit, which may process information by, for example, the following operations: converting the obtained information into other information, comparing the obtained information or the converted information with the information stored in the network node, and / or performing one or more operations based on the obtained information or the converted information, and making a determination as a result of the processing. In addition, although the components are depicted as a single box located within a larger box or nested within multiple boxes, in fact the computing device may include multiple different physical components constituting a single illustrated component, and functionality may be divided between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of these components may be divided between a processing circuit and a communication interface. In another example, the non-computationally intensive functions of any of such components may be implemented in software or firmware, and the computationally intensive functions may be implemented in hardware.

[0129] In some embodiments, some or all of the functionality described herein may be provided by a processing circuit that executes instructions stored in a memory, which in some embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by a processing circuit, such as in a hardwired manner, without executing instructions stored on a separate or discrete device-readable storage medium. In any of those specific embodiments, the processing circuit may be configured to perform the described functionality, regardless of whether instructions stored on a non-transitory computer-readable storage medium are executed. The benefits provided by such functionality are not limited to separate processing circuits or other components of a computing device, but are generally enjoyed by the computing device as a whole and / or by end users and wireless networks.

[0130] Example embodiments of the present disclosure are as follows: Group A Embodiment Embodiment 1: A method performed by a wireless terminal (e.g., user equipment (UE)), the method comprising one or more of the following steps: · receiving (300) a configuration from a first cell to perform a handover to a second cell, the configuration comprising an indication indicating a voice fallback purpose; · attempting (302) to connect to a second cell using mobility procedures; • determining (304) that a failure has occurred with respect to connecting to the second cell; Storing (306) information associated with the fault in a first report; attempting (308) to perform cell selection employing the same radio access technology as the second cell (or a second network node serving the second cell), and as a result selecting (308) a cell employing the same radio access technology as the second cell; - Storing (310) in a first report an indication whether the selected cell is a suitable cell or an acceptable cell. Embodiment 2: The method of embodiment 1, wherein the first cell is a cell of a first radio access technology RAT (eg, new radio NR), and the second cell is a cell of a second radio access technology (eg, EUTRA). Embodiment 3: The method of embodiment 1 or 2, wherein the first cell is operated by a first network node, and the second cell is operated by a second network node. Embodiment 4: The method of any one of embodiments 1 to 3, wherein the fault is a switching fault. Embodiment 5: The method of any one of embodiments 1 to 3, wherein the failure is a radio link failure (RLF) after a handover is successfully completed. Embodiment 6: The method of any one of embodiments 1 to 5, wherein the selected cell is a suitable cell. Embodiment 7: The method of any one of embodiments 1 to 5, wherein the selected cell is an acceptable cell. Embodiment 8: The method of any one of embodiments 1 to 5, wherein selecting a cell that adopts the same RAT as the second cell comprises: if there is no suitable cell, selecting an acceptable cell. Embodiment 9: The method of any one of embodiments 1 to 5, wherein selecting a cell that adopts the same RAT as the second cell comprises: selecting an acceptable cell even if a suitable cell exists. Embodiment 10: The method of any one of embodiments 1 to 5, wherein selecting a cell that adopts the same RAT as the second cell comprises: selecting a cell from another PLMN that is different from the PLMN in which the UE performed a handover toward the second cell. Embodiment 11: The method of embodiment 10 further comprises: storing (312) in the first report an indication of the PLMN identity of the selected cell. Embodiment 12: The method of embodiment 10 further comprises: storing (312) in the first report an indication indicating whether the PLMN of the selected cell is the same as the PLMN of the second cell. Embodiment 13: The method of any one of embodiments 1 to 9 further comprises: storing (312) in the first report an indication of the PLMN identity of the selected cell. Embodiment 14: The method of any one of embodiments 1 to 9 further comprises: storing (312) in the first report an indication indicating whether the PLMN of the selected cell is the same as the PLMN of the second cell. Embodiment 15: The method of any one of embodiments 1 to 14, wherein if the selected cell is not a suitable cell, the wireless terminal does not include the selected cell ID in the first report. Embodiment 16: The method of any one of embodiments 1 to 15, wherein the wireless terminal records and reports (eg, in a first report) an amount of time from the time of the failure to the time of selecting the first cell. Embodiment 17: The method of any one of embodiments 1 to 16, wherein the wireless terminal records and reports (for example, in a first report) information about whether the wireless terminal has detected one or more suitable cells and / or information about whether the wireless terminal has detected one or more acceptable cells. Embodiment 18: The method of any one of embodiments 1 to 17, further comprising: storing (314) in the first report an indication indicating whether emergency services are enabled for the selected cell. Embodiment 19: The method of any one of embodiments 1 to 18 further comprises: transmitting (316) a first report to a network node. Embodiment 20: The method of any of the preceding embodiments further comprises: providing user data; and forwarding the user data to the host via transmission to a network node. Group B Example Embodiment 21: A method performed by a network node, the method comprising: receiving a fault report (e.g., a HOF report or an RLF report) from a wireless terminal, the fault report comprising an indication of whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell. Embodiment 22: The method of any of the foregoing embodiments further comprises: obtaining user data; and forwarding the user data to a host or a user device. Group C Example Embodiment 23: A user device comprising: a processing circuit configured to perform any of the steps of any of the embodiments in Group A; and a power supply circuit configured to supply power to the processing circuit. Embodiment 24: A network node, comprising: a processing circuit configured to perform any of the steps of any of the embodiments in Group B; and a power supply circuit configured to supply power to the processing circuit. Embodiment 25: A user equipment (UE), comprising: an antenna configured to transmit and receive wireless signals; a radio front end circuit connected to the antenna and the processing circuit and configured to condition signals passed between the antenna and the processing circuit; · processing circuitry configured to perform any of the steps of any of the embodiments in Group A; an input interface connected to the processing circuitry and configured to allow information to be input into the UE for processing by the processing circuitry; an output interface connected to the processing circuit and configured to output information from the UE that has been processed by the processing circuit; and • A battery connected to the processing circuit and configured to provide power to the UE. Embodiment 26: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: a processing circuit configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE), wherein the UE comprises a communication interface and a processing circuit, the communication interface and processing circuit of the UE being configured to perform any of the steps of any of the embodiments in Group A to receive user data from the host. Embodiment 27: The host of the preceding embodiment, wherein the cellular network further comprises a network node configured to communicate with the UE to transmit user data from the host to the UE. Embodiment 28: The host of the aforementioned two embodiments, wherein: the processing circuit of the host is configured to execute a host application to provide user data; and the host application is configured to interact with a client application executed on the UE, and the client application is associated with the host application. Embodiment 29: A method implemented by a host operating in a communication system, the communication system further comprising a network node and a user equipment (UE), the method comprising: providing user data to the UE; and initiating a transmission carrying the user data to the UE via a cellular network including the network node, wherein the UE performs any of the operations of any of the embodiments in Group A to receive the user data from the host. Embodiment 30: The method of the aforementioned embodiment further comprises: executing, on the host, a host application associated with the client application executed on the UE to receive user data from the UE. Embodiment 31: The method of the aforementioned embodiment further comprises: at the host, transmitting input data to the client application executed on the UE, the input data being provided by executing the host application, wherein the user data is provided by the client application in response to the input data from the host application. Embodiment 32: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: a processing circuit configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE), wherein the UE comprises a communication interface and a processing circuit, the communication interface and processing circuit of the UE being configured to perform any of the steps of any of the embodiments in Group A to transmit the user data to the host. Embodiment 33: The host of the preceding embodiment, wherein the cellular network further comprises a network node configured to communicate with the UE to transmit user data from the UE to the host. Embodiment 34: The host of the aforementioned two embodiments, wherein: the processing circuit of the host is configured to execute a host application to provide user data; and the host application is configured to interact with a client application executed on the UE, and the client application is associated with the host application. Embodiment 35: A method implemented by a host, the host being configured to operate in a communication system, the communication system further comprising a network node and a user equipment (UE), the method comprising: at the host, receiving user data transmitted to the host by the UE via the network node, wherein the UE performs any of the steps of any of the embodiments in Group A to transmit the user data to the host. Embodiment 36: The method of the aforementioned embodiment further comprises: on a host, executing a host application associated with a client application executed on a UE to receive user data from the UE. Embodiment 37: The method of the aforementioned embodiment further comprises: at the host, transmitting input data to the client application executed on the UE, the input data being provided by executing the host application, wherein the user data is provided by the client application in response to the input data from the host application. Embodiment 38: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: a processing circuit configured to provide user data; and a network interface configured to initiate transmission of user data to a network node in a cellular network for transmission to a user equipment (UE), the network node having a communication interface and a processing circuit, the processing circuit of the network node being configured to perform any of the operations of any of the embodiments in Group B to transmit user data from the host to the UE. Embodiment 39: The host of the aforementioned embodiment, wherein: the processing circuit of the host is configured to execute a host application that provides user data; and the UE includes a processing circuit that is configured to execute a client application associated with the host application to receive a transmission of user data from the host. Embodiment 40: A method implemented in a host, the host being configured to operate in a communication system, the communication system further comprising a network node and a user equipment (UE), the method comprising: providing user data to the UE; and initiating a transmission carrying the user data to the UE via a cellular network including the network node, wherein the network node performs any of the operations of any of the embodiments in Group B to transmit the user data from the host to the UE. Embodiment 41: The method of the aforementioned embodiment further comprises: at a network node, transmitting user data provided by a host to a UE. Embodiment 42: The method of any one of the above two embodiments, wherein user data is provided on the host by executing a host application, the host application interacts with a client application executed on the UE, and the client application is associated with the host application. Embodiment 43: A communication system configured to provide an over-the-top service, the communication system comprising a host, the host comprising: a processing circuit configured to provide user data to a user equipment (UE), the user data being associated with the over-the-top service; and a network interface configured to initiate transmission of the user data toward a cellular network node for transmission to the UE, the network node having a communication interface and a processing circuit, the processing circuit of the network node being configured to perform any of the operations of any of the embodiments in Group B to transmit the user data from the host to the UE. Embodiment 44: The communication system of the aforementioned embodiment further comprises: a network node; and / or a user equipment. Embodiment 45: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: a processing circuit configured to initiate reception of user data; and a network interface configured to receive user data from a network node in a cellular network, the network node having a communication interface and a processing circuit, the processing circuit of the network node being configured to perform any of the operations of any of the embodiments in Group B to receive user data from a user equipment (UE) for the host. Embodiment 46: The host of the aforementioned two embodiments, wherein: the processing circuit of the host is configured to execute a host application to provide user data; and the host application is configured to interact with a client application executed on the UE, and the client application is associated with the host application. Embodiment 47: The host of any one of the above two embodiments, wherein initiating reception of user data includes requesting user data. Embodiment 48: A method implemented by a host, the host being configured to operate in a communication system, the communication system further comprising a network node and a user equipment (UE), the method comprising: at the host, initiating reception of user data from the UE, the user data originating from a transmission already received by the network node from the UE, wherein the network node performs any of the steps of any of the embodiments in Group B to receive user data from the UE for the host. Embodiment 49: The method of the aforementioned embodiment further comprises: at the network node, transmitting the received user data to the host.

[0131] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein.

Claims

1. A method performed by a wireless terminal, the method comprising: receiving (300) a configuration from a first cell to perform a handoff to a second cell, the configuration including an indication indicating a voice fallback purpose; attempting (302) to connect to the second cell using a mobility procedure; determining (304) that a failure has occurred with respect to connecting to the second cell; storing (306) information associated with the fault in a first report; attempting (308) to perform cell selection using the same radio access technology as the second cell; As a result of attempting (308) to perform cell selection, selecting (308) a cell that employs the same radio access technology as the second cell; as well as At least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell is stored (310) in the first report.

2. The method according to claim 1, wherein: A suitable cell is a cell on which a wireless terminal may camp, while an acceptable cell is a cell on which a wireless terminal may camp to obtain limited service.

3. The method according to claim 1 or 2, wherein: The first cell is a cell of a first radio access technology, RAT, and the second cell is a cell of a second radio access technology.

4. The method according to any one of claims 1 to 3, wherein: The first cell is operated by a first network node and the second cell is operated by a second network node.

5. The method according to any one of claims 1 to 4, wherein: The selected cell is operated by the same or a different network node as the network node operating the second cell.

6. The method according to any one of claims 1 to 5, wherein: The fault is a switching fault.

7. The method according to any one of claims 1 to 5, wherein: The failure is a radio link failure RLF after successful completion of the handover.

8. The method according to any one of claims 1 to 7, wherein: The selected cell is a suitable cell.

9. The method according to any one of claims 1 to 7, wherein: The selected cell is an acceptable cell.

10. The method according to any one of claims 1 to 7, wherein: Selecting (308) a cell employing the same radio access technology as the second cell comprises selecting (308) an acceptable cell if there are no suitable cells.

11. The method according to any one of claims 1 to 7, wherein: Selecting (308) a cell that employs the same radio access technology as the second cell includes selecting (308) an acceptable cell even if a suitable cell exists.

12. The method according to any one of claims 1 to 7, wherein: Selecting (308) a cell employing the same radio access technology as the second cell comprises selecting (308) a cell from a Public Land Mobile Network PLMN different from the one in which the wireless terminal performed the handover towards the second cell.

13. The method according to claim 12, further comprising: An indication of a PLMN identity of the selected cell is stored (312) in the first report.

14. The method according to claim 12, further comprising: An indication is stored (312) in the first report indicating whether the PLMN of the selected cell is the same as the PLMN of the second cell.

15. The method according to any one of claims 1 to 11, further comprising: An indication of a Public Land Mobile Network (PLMN) identity of the selected cell is stored (312) in the first report.

16. The method according to any one of claims 1 to 11, further comprising: An indication is stored (312) in the first report indicating whether the Public Land Mobile Network PLMN of the selected cell is the same as the PLMN of the second cell.

17. The method according to any one of claims 1 to 16, wherein: If the selected cell is not a suitable cell, the wireless terminal does not include the selected cell identification ID in the first report.

18. The method according to any one of claims 1 to 17, wherein: The wireless terminal records and reports the amount of time from the time of the failure to the time of selection of the selected cell.

19. The method according to any one of claims 1 to 18, wherein: The wireless terminal records and reports information regarding whether the wireless terminal has detected one or more suitable cells and / or information regarding whether the wireless terminal has detected one or more acceptable cells.

20. The method according to any one of claims 1 to 19, further comprising: An indication is stored (314) in the first report indicating whether emergency services are enabled for the selected cell.

21. The method according to any one of claims 1 to 20, further comprising: The first report is transmitted (316) to a network node.

22. A wireless terminal, the wireless terminal being adapted to: receiving (300) a configuration from a first cell to perform a handoff to a second cell, the configuration including an indication indicating a voice fallback purpose; attempting (302) to connect to the second cell using a mobility procedure; determining (304) that a failure has occurred with respect to connecting to the second cell; storing (306) information associated with the fault in a first report; attempting (308) to perform cell selection using the same radio access technology as the second cell; As a result of attempting (308) to perform cell selection, selecting (308) a cell that employs the same radio access technology as the second cell; as well as At least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell is stored (310) in the first report.

23. The wireless terminal according to claim 22, further adapted to perform the method of any one of claims 2 to 21.

24. A wireless terminal (500), comprising: Communication interface (512); as well as A processing circuit (502) associated with the communication interface (512), the processing circuit (502) being configured to cause the wireless terminal (500): receiving (300) a configuration from a first cell to perform a handoff to a second cell, the configuration including an indication indicating a voice fallback purpose; attempting (302) to connect to the second cell using a mobility procedure; determining (304) that a failure has occurred with respect to connecting to the second cell; storing (306) information associated with the fault in a first report; attempting (308) to perform cell selection using the same radio access technology as the second cell; As a result of attempting (308) to perform cell selection, selecting (308) a cell that employs the same radio access technology as the second cell; as well as At least one piece of information indicating whether the selected cell is a suitable cell or an acceptable cell is stored (310) in the first report.

25. The wireless terminal according to claim 24, wherein: The processing circuit (502) is further configured to cause the wireless terminal to perform the method of any one of claims 2 to 21.

26. A method performed by a network node of a Radio Access Network (RAN) for a cellular communication system, the method comprising: receiving (1000) a fault report from a wireless terminal, the fault report comprising at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell; as well as One or more actions are performed (1002) based on the fault report.

27. A network node for a Radio Access Network RAN ​​of a cellular communication system, the network node being adapted to: receiving (1000) a fault report from a wireless terminal, the fault report comprising at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell; and One or more actions are performed (1002) based on the fault report.

28. A network node (600) for a radio access network RAN ​​of a cellular communication system, the network node (600) comprising: Communication interface (606); as well as A processing circuit (602) associated with the communication interface (606), the communication interface (606) being configured to cause the network node (600): receiving (1000) a fault report from a wireless terminal, the fault report comprising at least one piece of information indicating whether a selected cell selected by the wireless terminal after experiencing an associated fault is a suitable cell or an acceptable cell; as well as One or more actions are performed (1002) based on the fault report.

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