Method and device for MRO mechanism for inter-RAT handover procedure

Abstract

Embodiments of the present application relate to methods and devices for a mobility robustness optimization (MRO) mechanism for an inter-radio access technology (RAT) handover procedure. According to an embodiment of the present application, a method may include: receiving a mobile command message from a source new radio (NR) cell, wherein the mobile command message includes an identifier (ID) of a target cell, and the target cell is at least one of an evolved universal terrestrial radio access network (E‑UTRAN) cell and a universal terrestrial radio access network (UTRAN) cell; determining whether a timer (e.g., timer T312) for initiating failure recovery based on a triggered measurement report is running; and in response to the timer being running, stopping the timer. In addition, a radio link failure report (RLF) information is transmitted to the network in response to an inter-RAT handover failure from NR to E‑UTRAN and UTRAN.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technology, and more particularly, to methods and apparatus for a mobility robustness optimization (MRO) mechanism for an inter-radio access technology (RAT) handover procedure. Background Art

[0002] A base station (BS) may have some cells (or areas) to provide communication services. When a user equipment (UE) moves from a serving cell of a source BS to a target cell of a target BS, a handover procedure is performed.

[0003] When a UE experiences a radio link failure (RLF) or a handover failure (HOF), the UE may perform a radio resource control (RRC) reestablishment procedure. The UE may access the cell through a successful RRC reestablishment procedure. The access network will request UE information including the UE's RLF report so that the network can optimize mobility issues based on the UE information from the UE. Therefore, the UE will transmit a failure report to the network.

[0004] The 3rd Generation Partnership Project (3GPP) 5G New Radio (NR) adopts an MRO mechanism. However, details of the MRO mechanism for inter-RAT handover procedures have not yet been discussed in 3GPP 5G NR technology. Summary of the invention

[0005] Some embodiments of the present application provide a method, which can be performed by a UE. The method includes: receiving a mobile command message from a source NR cell, wherein the mobile command message includes an identifier (ID) of a target cell, and the target cell is at least one of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell and a Universal Terrestrial Radio Access Network (UTRAN) cell; determining whether a timer (e.g., timer T312) for initiating failure recovery based on a triggered measurement report is running; and in response to the timer being running, stopping the timer.

[0006] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the method performed by the UE mentioned above.

[0007] Some embodiments of the present application provide another method, which can be performed by a UE. The method includes: receiving an RRC release message from a source NR cell, wherein the RRC release message includes a voice fallback indication, and wherein the voice fallback indication indicates that the RRC release message is triggered by a voice fallback operation; entering an RRC idle state; performing a cell selection procedure; in response to being unable to establish a connection with an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell after selecting the E-UTRAN cell or in response to being unable to select the E-UTRAN cell, selecting an NR cell; and transmitting radio link failure (RLF) report information to a serving cell.

[0008] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the method performed by the UE mentioned above.

[0009] Some embodiments of the present application provide another method, which can be performed by a BS. The method includes: transmitting a mobile command message to a UE, wherein the mobile command message includes an ID of a target cell of the UE, and the target cell is at least one of an E-UTRAN cell and a UTRAN cell; and receiving RLF report information.

[0010] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the method performed by the BS mentioned above.

[0011] Some embodiments of the present application provide another method, which can be performed by a BS. The method includes: transmitting an RRC release message including a voice fallback indication to a UE, wherein the voice fallback indication indicates that the RRC release message is triggered by a voice fallback operation; and receiving RLF report information.

[0012] Some embodiments of the present application also provide an apparatus for wireless communication. The apparatus includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the above-mentioned another method performed by the BS.

[0013] The details of one or more examples are set forth in the accompanying drawings and the description below. Additional features, objects, and advantages will become apparent from the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present disclosure is presented by reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and are therefore not to be considered limiting the scope of the present application.

[0015] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0016] Figure 2 An exemplary flow chart illustrating moving from a NR procedure according to some embodiments of the present application;

[0017] Figure 3 Another exemplary flow chart illustrating moving from a NR program according to some embodiments of the present application;

[0018] Figure 4 An exemplary flow chart illustrating a UE information procedure according to some embodiments of the present application;

[0019] Figure 5 A flowchart illustrating a method for switching programs according to some embodiments of the present application;

[0020] Figure 6 Another flow chart illustrating a method for a fault information program according to some embodiments of the present application;

[0021] Figure 7 A flowchart illustrating a method for receiving RLF report information according to some embodiments of the present application;

[0022] Figure 8 Another flowchart illustrating a method for receiving RLF report information according to some embodiments of the present application; and

[0023] Fig. 9 An exemplary block diagram illustrating an apparatus according to some embodiments of the present application. DETAILED DESCRIPTION

[0024] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application, and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be completed by different embodiments that are intended to be included in the spirit and scope of the present application.

[0025] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., 3GPP 5G, 3GPP LTE Release 8, etc.). It is considered that, with the development of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and in addition, the terms cited in the present application may be changed, which should not affect the principles of the present application.

[0026] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application.

[0027] like Figure 1 , a wireless communication system 100 includes at least one user equipment (UE) 101 and at least one base station (BS) 102. Specifically, for illustrative purposes, the wireless communication system 100 includes one UE 101 (e.g., UE 101a) and three BSs 102 (e.g., BS 102a, BS 102b, and BS 102c). Figure 1 A specific number of UEs 101 and BSs 102 are depicted in FIG. 1 , but it is contemplated that any number of UEs 101 and BSs 102 may be included in wireless communication system 100 .

[0028] UE 101 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a car computer, a network device (e.g., a router, a switch and a modem), an Internet of Things (IoT) device or the like. According to some embodiments of the present application, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a user identity module, a personal computer, a selective call receiver or any other device capable of transmitting and receiving communication signals on a wireless network. In some embodiments of the present application, UE 101 includes a wearable device, such as a smart watch, a fitness bracelet, an optical head-mounted display or the like. In addition, UE 101 may be referred to as a user unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a user station, a user terminal or a device, or described using other terms used in the art. UE 101 may communicate directly with BS 102 via an uplink (UL) communication signal.

[0029] In some embodiments of the present application, each of UE 101 may be deployed with IoT applications, eMBB applications, and / or URLLC applications. It is contemplated that the specific types of applications deployed in UE 101 may vary and are not limited.

[0030] BS102 may be distributed throughout a geographic area. In certain embodiments of the present application, each of BS102 may also be referred to as an access point, access terminal, base station, base unit, macro cell, Node B, evolved Node B (eNB), gNB, NG-RAN (Next Generation Radio Access Network) node, home Node B, relay node or device, or described using other terms used in the art. BS102 is typically part of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding BS102.

[0031] The wireless communication system 100 may be compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, the wireless communication system 100 may be compatible with: a wireless communication network, a cellular telephone network, a network based on time division multiple access (TDMA), a network based on code division multiple access (CDMA), a network based on orthogonal frequency division multiple access (OFDMA), an LTE network, a network based on 3GPP, a 3GPP 5G network, a satellite communication network, a high altitude platform network, and / or other communication networks.

[0032] In some embodiments of the present application, the wireless communication system 100 is compatible with the 5G NR of the 3GPP protocol, wherein the BS 102 transmits using an OFDM modulation scheme on the DL, and the UE 101 transmits data using a single carrier frequency division multiple access (SC-FDMA) or OFDM scheme on the UL. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0033] In some embodiments of the present application, BS102 may communicate using other communication protocols, such as the IEEE 802.11 series of wireless communication protocols. In addition, in some embodiments of the present application, BS102 may communicate via licensed spectrum, while in other embodiments, BS102 may communicate via unlicensed spectrum. The present application is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In some further embodiments of the present application, BS102 may communicate with UE 101 using 3GPP 5G protocols.

[0034] Each BS 102 may include one or more cells. Each UE 101 may perform a cell selection procedure between different cells of different BSs. Each UE 101 may switch from a serving cell of a source BS to a target cell of a target BS. Figure 1 In the wireless communication system 100 described and shown in FIG. 1 , BS 102 a may be used as a source BS, and each of BS 102 b and BS 102 c may be used as a target BS. Figure 1 UE 101a illustrated and described in FIG. 1 may perform a handover procedure from a serving cell of BS 102a to a target cell of BS 102b or a target cell of BS 102c, depending on the result of the cell selection procedure. The handover procedure performed by UE 101a may be a CHO procedure.

[0035] According to some agreements of 3GPP standard documents, during the handover procedure from 5G to LTE (ie 4G), the characteristics of inter-RAT handover are as follows:

[0036] - The source RAT BS configures measurement information and the target RAT BS configures reporting.

[0037] - The source RAT BS decides the handover procedure and provides the necessary information to the target RAT BS.

[0038] - Radio resources are reserved in the target RAT BS before the UE accesses the target RAT BS.

[0039] - The RRC reconfiguration message from the target RAT BS is delivered to the source RAT BS as a transparent container and transmitted by the source RAT BS to the UE in a handover command. For example, the source BS transmits a MobilityFromNRCommand message to the UE, and the MobilityFromNRCommand message includes the RRC reconfiguration message provided by the target RAT BS.

[0040] According to some protocols of 3GPP standard documents, during the handover procedure from 5G to 3G, Single Radio Voice Call Continuity (SRVCC) operation is performed. The source NR node decides to handover a UE that is performing Internet Protocol Multimedia Subsystem (IMS) voice from NR to UTRAN based on the following principles:

[0041] -Configure measurement information for the source NR node and reporting configuration for the target UTRAN node.

[0042] - The source NR node determines that a handover procedure should be initiated to the target UTRAN node.

[0043] - The source NR node initiates the handover procedure only for the ongoing IMS voice and provides an indication to the Access and Mobility Management Function (AMF) indicating that the handover is towards UTRAN together with the identifier (ID) of the target UTRAN node. The source NR node also indicates to the target UTRAN node that the incoming handover originates from the 5G system.

[0044] - Radio resources are reserved in the target RAT BS (ie target UTRAN node) before the UE accesses the target RAT BS.

[0045] - The RRC reconfiguration message from the target RAT BS is delivered to the source NR node via a transparent container and passed by the source NR node to the UE in a handover command. For example, the source BS transmits a MobilityFromNRCommand message including the RRC reconfiguration message provided by the target RAT BS to the UE.

[0046] In addition, 3GPP TS 38.331 defines the mobility procedure from NR to 4G or 3G. The purpose of the mobility procedure is to move a UE in the RRC_CONNECTED state to a cell using another RAT, such as an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell or a UTRAN-Frequency Division Duplex (FDD) cell. Figures 2 to 4 Described in.

[0047] Figure 2 An exemplary flowchart illustrating movement from an NR program according to some embodiments of the present application. Figure 2 The embodiments are performed by a UE which aims to switch from a serving cell of a source BS to a candidate cell of a target BS.

[0048] like Figure 2 As shown in FIG. 2 , in step 201, a BS (e.g., Figure 1 BS102a, BS102b or BS102c described and shown in the figure initiates the movement from the NR procedure to the UE (e.g., as shown in the figure) by transmitting a MobilityFromNRCommand message to the UE. Figure 1 101a). The BS is a source BS that controls a serving cell of the UE. The UE may be in an RRC_CONNECTED state. For example, the MobilityFromNRCommand message includes radio resources that have been allocated to the UE in a candidate cell of the target BS.

[0049] Figure 3 Another exemplary flow chart illustrating moving from a NR program according to some embodiments of the present application. Figure 2 , Figure 3 The embodiments are performed by a UE which aims to switch from a serving cell of a source BS to a candidate cell of a target BS.

[0050] like Figure 3 As shown in FIG. 3 , in step 301, a BS of NR RAT type (e.g., Figure 1BS102a, BS102b or BS102c described and shown in the figure initiates the movement from the NR procedure to the UE (e.g., as shown in the figure) by transmitting a MobilityFromNRCommand message to the UE. Figure 1 101a). The BS is a source BS that controls a serving cell of the UE. The UE may be in an RRC_CONNECTED state. For example, the MobilityFromNRCommand message includes radio resources in a candidate cell of a target BS that has been allocated to the UE.

[0051] If a failure occurs during the inter-RAT handover procedure of the UE, the UE reestablishes to a cell, which may be a source cell, a target cell, or an additional cell. For example, as shown in step 302, if no failure occurs during the inter-RAT handover procedure, the UE may perform an RRC reestablishment procedure to the source cell of the BS that sent the MobilityFromNRCommand message. Alternatively, if a failure occurs during the inter-RAT handover procedure, the UE may perform an RRC reestablishment procedure to a candidate cell of the target BS or the UE may perform an RRC reestablishment procedure to a cell different from the source cell or the candidate target cell.

[0052] Figure 4 An exemplary flow chart illustrating a UE information procedure according to some embodiments of the present application.

[0053] Figure 4 The UE information procedure in the embodiment of is used by a BS for the purpose of requesting the UE to report information. Specifically, the UE may reestablish to a cell after RLF or HOF occurs. The UE may access the cell after the UE enters the RRC idle state due to an RRC reestablishment failure. The UE may transmit an indication to the source BS indicating RLF information available to the source BS. After the source BS receives the failure information available from the UE, the source BS transmits a UEinformationrequest message to the UE.

[0054] like Figure 4 As shown in FIG. 4 , in step 401, a source BS (eg, Figure 1 BS102a, BS 102b, or BS102c described and shown in FIG. 102B) transmits a UEInformationRequest message to a UE (e.g., Figure 1The source BS initiates the UE information procedure by using the UE 101a) described and shown in FIG. 4. The source BS should initiate this UE information procedure only after successful security activation. In step 402, after receiving the UEInformationRequest message, the UE reports the UEInformationRequest message to the source BS. For example, the UE transmits the UEInformationRequest message including the RLF report to the source BS. When RLF occurs, the UEInformationRequest message may include the RLF report.

[0055] Generally speaking, the purpose of the MEO mechanism is to detect and enable problem correction of RLF, HOF or ping-pong problems. In 3GPP Release 16, RLF or HOF may occur during the inter-RAT handover procedure. However, an MRO mechanism for the inter-RAT handover procedure has not yet been designed. Embodiments of the present application provide solutions for the MRO mechanism for the inter-RAT handover procedure.

[0056] The following table shows a description of some timers as specified in 3GPP standard documents, including the start condition, stop condition, action upon expiration, and possible common names for each of these timers.

[0057]

[0058] Figure 5 Flowchart illustrating a method for a handover procedure according to some embodiments of the present application. Method 500 may be performed by a UE (e.g., Figure 1 UE 101 shown and described in Figures 2 to 4 Although described with respect to a UE, it should be understood that other devices may be configured to perform similar Figure 5 method of method of method.

[0059] In such Figure 5 In the exemplary method 500 shown in FIG. 5 , in operation 502, the UE receives a mobility command message from a source NR cell. The mobility command message may include an ID of a target cell. The target cell is at least one of an E-UTRAN cell and a UTRAN cell. In an embodiment, the mobility command message is a MobilityFromNRCommand message as specified in a 3GPP standard document.

[0060] In an embodiment, the UE performs a handover procedure to a target cell indicated in the mobility command message. In an embodiment, the UE further receives an RRC reconfiguration message including CHO configuration information associated with one or more candidate cells. The UE may determine whether the selected candidate cell is configured with the CHO configuration information. If the UE determines that the selected candidate cell is configured with the CHO configuration information, the UE may perform a CHO procedure to the selected candidate cell.

[0061] If a handover failure occurs during a handover procedure (eg, a CHO procedure), the UE performs a cell selection procedure and selects a suitable candidate cell. The UE may then initiate an RRC reestablishment procedure to the selected candidate cell.

[0062] For example, the selected candidate cell may be a NR cell, an E-UTRAN cell or a UTRAN cell. In an embodiment, if the UE finds one or more candidate cells during the cell selection procedure, and if the one or more candidate cells found include at least one UTRAN cell, the UE selects the UTRAN cell as the selected candidate cell.

[0063] If a handover failure occurs during the handover procedure, the UE may transmit the RLF report information. In an embodiment, if the move command message includes a voice fallback indication, the RLF report information includes an indicator for indicating that the handover procedure is for voice fallback operation.

[0064] In an embodiment, the RLF report information includes an indicator for indicating: (1) no E-UTRAN cell for voice fallback operation is found; or (2) no UTRAN cell for voice fallback operation is found.

[0065] In an embodiment, the RLF report information includes an ID of the target cell. In an embodiment, if the handover procedure is performed between different radio access technologies (RATs), the RLF report information includes the RAT type of the target cell. The RAT type may be E-UTRAN or UTRAN-FDD.

[0066] In an embodiment, if the selected candidate cell is a UTRAN cell, the RLF report information is transmitted to the BS serving the UE (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4The BS serving the UE may forward the message including the RLF report information to the source BS associated with the source NR cell. For example, the BS serving the UE transmits the message including the RLF report information to the AMF, and the AMF is associated with the source NR cell. Then, the AMF transmits the message including the RLF report information to the source BS associated with the source NR cell.

[0067] Return to reference Figure 5 In operation 504, the UE determines whether a timer for initiating failure recovery based on a triggered measurement report is running. In operation 506, if the UE determines that the timer is running, the UE stops the timer. In an embodiment, the timer is a timer T312 as specified in a 3GPP standard document. The UE determines whether the timer T312 is running and stops the timer T312 when it is running.

[0068] The following text description Figure 5 Four specific embodiments of the method shown and described in .

[0069] Example 1

[0070] According to Embodiment 1, a UE (e.g. Figure 1 UE 101 shown and described in Figures 2 to 4 ) and a BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 One of the BSs shown and described in the specification) performs the following operations:

[0071] (1) The source BS decides to move the UE to an LTE cell (eg, an E-UTRAN cell) for voice services.

[0072] (2) The UE receives the MobilityFromNRCommand message from the source BS.

[0073] • After receiving the MobilityFromNRCommand message, if the timer T312 is running, the UE stops the timer.

[0074] ●The MobilityFromNRCommand message contains the voice fallback indication.

[0075] (3) The UE accesses the target LTE cell (e.g., E-UTRAN cell) indicated in the MobilityFromNRCommand message.

[0076] ●UE starts timer T304.

[0077] (4) The UE is unable to establish a connection to the target LTE cell, for example, after timer T304 expires.

[0078] (5) The UE performs a cell selection procedure. The cell selection procedure may include the following situations.

[0079] a) If a suitable LTE cell (eg, an E-UTRAN cell) is selected during the cell selection procedure, the UE goes to RRC_IDLE state and performs a connection establishment procedure to the selected LTE cell.

[0080] b) After accessing the selected LTE cell (ie, E-UTRAN cell), the UE transmits an RLF report to the BS of the LTE cell serving the UE (ie, LTE serving cell (ie, E-UTRAN cell)).

[0081] i. The UE reports an RLF report to the LTE serving cell. The RLF report may include additional auxiliary information indicating whether the voiceFallbackIndication is included in the MobilityFromNRCommand message. That is, the RLF report may include an indicator for indicating whether this handover procedure is performed for voice fallback purposes. For example, the voice fallback indication is included in the RLF report.

[0082] c) The BS of the LTE serving cell receives the RLF report from the UE and then transmits the RLF report to the source BS.

[0083] A. If no suitable LTE cell (e.g., E-UTRAN cell) is selected during the cell selection procedure, the UE may select an NR cell for performing the RRC re-establishment procedure.

[0084] B. The UE reports an RLF report to the BS of the selected NR. The RLF report may include at least one of the following additional assistance information:

[0085] ii. Auxiliary information indicating whether voiceFallbackIndication is included in the MobilityFromNRCommand message. That is, the RLF report may include an indicator for indicating whether this handover procedure is performed for voice fallback purposes. For example, the voice fallback indication is included in the RLF report.

[0086] iii. Assistance information indicating that no suitable E-UTRAN cell was found for voice fallback purposes when voiceFallbackIndication is configured.

[0087] C. The BS of the selected NR cell receives the RLF report from the UE and then transmits the RLF report to the target BS associated with the failed handover procedure.

[0088] Example 2

[0089] According to Embodiment 2, a UE (e.g. Figure 1 UE 101 shown and described in Figures 2 to 4 ) and a BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 One of the BSs shown and described in the specification) performs the following operations:

[0090] (1) The source NR BS decides to hand over the UE to the UTRAN cell for voice services.

[0091] (2) The UE receives the MobilityFromNRCommand message from the source NR BS.

[0092] • After receiving the MobilityFromNRCommand message, if the timer T312 is running, the UE stops the timer T312.

[0093] ●The MobilityFromNRCommand message contains voiceFallbackIndication.

[0094] (3) The UE accesses the target UTRAN cell indicated in the MobilityFromNRCommand message.

[0095] ●UE starts timer T304.

[0096] (4) The UE cannot establish a connection to the target UTRAN cell, for example, after timer T304 expires. Alternatively, RLF occurs in 3G after the UE succeeds in a handover procedure within a period.

[0097] (5) The UE performs a cell selection procedure for the purpose of RRC re-establishment.

[0098] ● If the UE is unable to perform the handover procedure from 5G to 3G or RLF occurs in 3G, the UE shall perform the RRC re-establishment procedure. If a suitable UTRAN cell is available during the cell selection procedure, the UE shall select the suitable UTRAN cell for the RRC re-establishment procedure. Otherwise, the UE may select another suitable cell (e.g., NR cell) for RRC re-establishment purposes.

[0099] (6) After accessing a UTRAN cell or an NR cell, the UE transmits an RLF report to the serving cell. The RLF report may include at least one of the following additional assistance information:

[0100] - Assistance information indicating whether the handover procedure is an inter-RAT handover procedure. That is, the assistance information indicates whether the handover procedure is of the inter-RAT type.

[0101] ● If the handover procedure is an inter-RAT handover procedure, auxiliary information indicating whether the target cell is E-UTRAN or UTRAN-FDD.

[0102] i. For example, the RLF report includes a targetRAT-Type IE, which indicates the RAT type of the target cell. The targetRAT-Type IE may be one of E-UTRAN and UTRAN-FDD. In an embodiment, the targetRAT-Type may be listed as {eutran,utran-fdd}.

[0103] ●Auxiliary information indicating the ID of the target cell.

[0104] i. For example, the RLF report may include the ID of the target UTRAN cell of the failed handover procedure. In an embodiment, the field "FailedPCellid-UTRAN" or "FailedPCellid-UTRA" is used to indicate the ID of the target UTRAN cell in which the RLF was detected.

[0105] (7) The UTRAN cell receives the RLF report from the UE. The UTRAN cell then transmits the RLF report as a container to the core network (CN). The node of the UTRAN CN will forward the information containing the RLF report to the AMF associated with the source NR cell.

[0106] (8)AMF shall transmit the received information including the RLF report to the source NR BS.

[0107] Example 3

[0108] According to Embodiment 3, a UE (e.g. Figure 1 UE 101 shown and described in Figures 2 to 4 ) and a BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 One of the BSs shown and described in the specification) performs the following operations:

[0109] (1) The source BS transmits the target RAT measurement and reporting configuration information to the UE.

[0110] (2) The source BS determines a target cell for the target BS in another RAT and sends a handover request including necessary information (eg, UE context) to the target BS.

[0111] (3) The target BS transmits the RRC reconfiguration message to the source BS.

[0112] (4) The source BS transmits a MobilityFromNRCommand message to the UE. The MobilityFromNRCommand message includes the RRC reconfiguration message transmitted from the target BS.

[0113] (5) The UE receives a MobilityFromNRCommand message from the network. The MobilityFromNRCommand message indicates information about a target cell of a target BS.

[0114] • After receiving the MobilityFromNRCommand message, if the timer T312 is running, the UE stops the timer.

[0115] (6) The UE accesses the target cell of the target BS.

[0116] Example 4

[0117] According to Embodiment 4, a UE (e.g. Figure 1 UE 101 shown and described in Figures 2 to 4 ) and a BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 One of the BSs shown and described in the specification) performs the following operations:

[0118] (1) The UE receives CHO configuration information.

[0119] (2) The UE receives the MobilityFromNRCommand message from the source NR BS.

[0120] • After receiving the MobilityFromNRCommand message, if the timer T312 is running, the UE stops the timer T312.

[0121] (3) The UE accesses the target cell indicated in the MobilityFromNRCommand message.

[0122] ●UE starts timer T304.

[0123] (4) The UE does not successfully establish a connection to the target cell, for example, after timer T304 expires.

[0124] (5) The UE initiates the RRC reestablishment procedure and starts the timer T311 for the cell selection procedure.

[0125] (6) The UE performs the cell selection procedure and selects a suitable NR cell.

[0126] ●UE stops timer T311.

[0127] (7) The UE applies the associated stored CHO configuration information to the selected appropriate NR cell, and if the selected cell is configured with the CHO configuration information, performs the CHO procedure.

[0128] ● In the example, attemptCondReconfig IE is used to indicate that the CHO configuration information is allowed for the UE. For example, the UE is allowed to perform the CHO procedure to the selected cell under the following conditions:

[0129] - "Cell selection triggered by inter-RAT handover procedure failure from NR",

[0130] - "attemptCondReconfig IE is configured", and

[0131] - "The selected cell has been configured with CHO configuration information".

[0132] The details described in all other embodiments of the present application (for example, the details of the MRO mechanism of the inter-RAT handover procedure and the auxiliary information in the RLF report information) are applicable to Figure 5 In addition, Figure 5 The details described in the embodiments may be applied to Figures 1 to 4 And all embodiments of 6 to 9.

[0133] Figure 6 Another flowchart illustrating a method for a fault information procedure according to some embodiments of the present application. The method 600 may be performed by a UE (e.g., Figure 1 UE 101 shown and described in Figures 2 to 4 Although described with respect to a UE, it should be understood that other devices may be configured to perform similar Figure 6 method of method of method.

[0134] In such Figure 6In the exemplary method 600 shown in FIG. 1 , at operation 602, the UE receives an RRC release message from a source NR cell. The RRC release message includes a voice fallback indication. The voice fallback indication indicates that the RRC release message is triggered by a voice fallback operation. At operation 604, the UE enters an RRC idle state.

[0135] In operation 606, the UE performs a cell selection procedure. In operation 608, if the UE cannot establish a connection with the E-UTRAN cell after selecting the E-UTRAN cell or if the UE cannot select the E-UTRAN cell, the UE selects the NR cell. In operation 610, the UE transmits RLF report information to the serving cell of the UE.

[0136] In an embodiment, the serving cell is the same as the source NR cell. In other words, the UE may reselect back to the source NR cell as its serving cell. In another embodiment, the serving cell is a cell different from the source NR cell. In other words, the UE may select a different cell as its serving cell.

[0137] In an embodiment, the RLF report information includes an indicator for indicating that the RRC release message includes a voice fallback indication. In another embodiment, the RLF report information includes an indicator for indicating that no E-UTRAN cell was found during the cell selection procedure. In another embodiment, the RLF report information includes an ID of the source NR cell.

[0138] The following text describes Figure 6 Specific embodiment 5 of the method shown and described in.

[0139] According to Embodiment 5, a UE (e.g. Figure 1 UE 101 shown and described in Figures 2 to 4 ) and a BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 One of the BSs shown and described in the specification) performs the following operations:

[0140] (1) The NR BS decides to move the UE to the E-UTRAN cell for voice services.

[0141] (2) The UE receives an RRC release message containing voiceFallbackIndication from the source cell of the NR BS.

[0142] (3) The UE attempts to select an accessible E-UTRAN cell, but a failure occurs during the handover procedure to the selected E-UTRAN cell.

[0143] (4) The UE may reselect back to the source cell. Alternatively, the UE may select a cell that is different from both the source cell and the selected E-UTRAN cell. When the UE can access the source cell or a different cell, the UE needs to report RLF report information. More specifically, the RLF report information may include the following potential auxiliary information:

[0144] ● an indicator to instruct the UE to receive an RRC Release message containing voiceFallbackIndication;

[0145] • After receiving the RRC Release message containing the voiceFallbackIndication, no suitable E-UTRAN cell was found for voice fallback purposes.

[0146] ●The ID of the source cell that transmits the RRC release message containing voiceFallbackIndication.

[0147] The details described in all other embodiments of the present application (for example, the details of the MRO mechanism of the inter-RAT handover procedure and the auxiliary information in the RLF report information) are applicable to Figure 6 In addition, Figure 6 The details described in the embodiments may be applied to Figures 1 to 5 And all embodiments of 7 to 9.

[0148] Figure 7 700 is a flowchart illustrating a method for receiving RLF report information according to some embodiments of the present application. The method 700 may be performed by a BS or a source BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 Although described with respect to a BS, it should be understood that other devices may be configured to perform similar Figure 7 method of method of method.

[0149] In such Figure 7 In the exemplary method 700 shown in FIG. 7 , in operation 702, the source BS transmits a mobile command message to the UE (eg, Figure 1 UE 101 shown and described in Figures 2 to 4 The mobility command message includes an ID of a target cell of the UE. The target cell is at least one of an E-UTRAN cell and a UTRAN cell.

[0150] In an embodiment, the mobility command message is a MobilityFromNRCommand message as specified in a 3GPP standard document. The mobility command message may include a voice fallback indication (eg, voiceFallbackIndication as specified in a 3GPP standard document).

[0151] In operation 704, the source BS receives RLF report information, for example, from a UE.

[0152] In an embodiment, if the move command message includes a voice fallback indication (eg, voiceFallbackIndication as specified in a 3GPP standard document), the RLF report information includes an indicator for indicating that the handover procedure is for voice fallback operation.

[0153] In another embodiment, the RLF report information includes an indicator for indicating that no E-UTRAN cell for voice fallback operation is found. In another embodiment, the RLF report information includes an indicator for indicating that no UTRAN cell for voice fallback operation is found.

[0154] In another embodiment, the BS serving the UE forwards the message to the source BS, and the message includes the RLF report information. In an example, the serving BS transmits the message including the RLF report information to the AMF, and the AMF forwards the message to the source BS.

[0155] In an embodiment, the RLF report information includes the ID of the target cell of the UE.

[0156] The details described in all other embodiments of the present application (for example, the details of the MRO mechanism of the inter-RAT handover procedure and the auxiliary information in the RLF report information) are applicable to Figure 7 In addition, Figure 7 The details described in the embodiments may be applied to Figures 1 to 6 , 8 and 9 of all embodiments.

[0157] Figure 8 Another flowchart of a method for receiving RLF report information according to some embodiments of the present application is shown. The method 800 may be performed by a BS or a source BS (e.g., Figure 1 BS102a, BS102b or BS102c as described and shown in Figures 2 to 4 Although described with respect to a BS, it should be understood that other devices may be configured to perform similar Figure 8 method of method of method.

[0158] In such Figure 8In the exemplary method 800 shown in FIG. 8 , in operation 802, the BS may transmit an RRC release message to the UE (eg, Figure 1 UE 101 shown and described in Figures 2 to 4 The RRC release message includes a voice fallback indication (e.g., voiceFallbackIndication as specified in a 3GPP standard document). The voice fallback indication indicates that the RRC release message is triggered by a voice fallback operation. In some cases, the UE cannot select a suitable E-UTRAN cell or the UE cannot establish a connection with the E-UTRAN cell after selecting the E-UTRAN cell. Therefore, in these cases, the UE selects an NR cell. The UE may transmit the RLF report information to the serving cell after the UE accesses the selected NR cell.

[0159] In operation 804, the source BS receives the RLF report. In an example, if the selected NR cell is the source cell of the UE, the UE will transmit the RLF report information to the source BS. In another example, if the selected NR cell is not the source cell, the UE will transmit the RLF report information to the serving BS. Then, the serving BS will transmit the received RLF report information to the source BS.

[0160] In an embodiment, the RLF report information includes an indicator for indicating that the RRC release message includes a voice fallback indication.

[0161] In another embodiment, the RLF report information includes an indicator for indicating that no E-UTRAN cell was found during the cell selection procedure of the UE.

[0162] In another embodiment, the RLF report information includes the ID of the source NR cell of the UE.

[0163] The details described in all other embodiments of the present application (for example, the details of the MRO mechanism of the inter-RAT handover procedure and the auxiliary information in the RLF report information) are applicable to Figure 8 In addition, Figure 8 The details described in the embodiments may be applied to Figures 1 to 7 And all embodiments of 9.

[0164] Fig. 9 An exemplary block diagram of a device according to some embodiments of the present application is shown. In some embodiments of the present application, the device 900 may be a UE, which may at least perform Figure 5 or Figure 6 In some embodiments of the present application, the device 900 may be a BS (eg, a source BS), which may at least perform Figure 7 or Figure 8 The method described in .

[0165] like Fig. 9 As shown in FIG. 1 , an apparatus 900 may include at least one receiver 902 , at least one transmitter 904 , at least one non-transitory computer-readable medium 906 , and at least one processor 908 coupled to the at least one receiver 902 , the at least one transmitter 904 , and the at least one non-transitory computer-readable medium 906 .

[0166] Despite Fig. 9 900, elements such as at least one receiver 902, at least one transmitter 904, at least one non-transitory computer-readable medium 906, and at least one processor 908 are described in the singular, but unless explicitly stated to be limited to the singular, the plural is contemplated. In some embodiments of the present application, at least one receiver 902 and at least one transmitter 904 are combined into a single device, such as a transceiver. In certain embodiments of the present application, the apparatus 900 may further include an input device, a memory, and / or other components.

[0167] In some embodiments of the present application, at least one non-transitory computer-readable medium 906 may store computer-executable instructions, which may be programmed to implement the operations of the method using at least one receiver 902, at least one transmitter 904, and at least one processor 908, such as according to Figures 5 to 8 Any description in .

[0168] It should be understood by those of ordinary skill in the art that the operations of the methods described in conjunction with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In addition, in some aspects, the operations of the methods may reside as one or any combination of a code set and / or an instruction set on a non-transitory computer-readable medium that can be incorporated into a computer program product.

[0169] Although the present disclosure has been described with reference to specific embodiments of the present disclosure, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, the various components of the embodiments may be interchangeable, newly added, or substituted in other embodiments. Moreover, all elements of each figure are not necessarily necessary for the operation of the disclosed embodiments. For example, a person of ordinary skill in the art will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0170] In this document, the term "includes / including" or any other variation thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device containing a list of elements not only contains those elements but also may contain other elements that are not explicitly listed or inherent to this process, method, article or device. Elements beginning with "a / an" or the like do not exclude the presence of additional identical elements in the process, method, article or device containing the element without more constraints. Moreover, the term "another" is defined as at least a second or more. As used herein, the term "having" and the like are defined as "comprising".

Claims

1. A device for wireless communication, comprising: at least one non-transitory computer-readable medium having computer-executable instructions stored thereon; at least one receiving circuit system; at least one transmission circuit system; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry, The computer executable instructions cause the at least one processor to implement a method comprising: receiving a move command message from a source New Radio (NR) cell, wherein the move command message includes an identifier (ID) of a target cell, and the target cell is at least one of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) cell and a Universal Terrestrial Radio Access Network (UTRAN) cell; determining whether a timer for initiating failure recovery based on triggering a measurement report is running; and In response to the timer being running, stopping the timer.

2. The apparatus according to claim 1, further comprising: executing a handover procedure to the target cell; In response to a handover failure occurring during the handover procedure, performing a cell selection procedure and selecting a candidate cell; and A Radio Resource Control (RRC) re-establishment procedure is initiated to the selected candidate cell.

3. The apparatus according to claim 2, wherein the selected candidate cell is at least one of a NR cell, an E-UTRAN cell, and a UTRAN cell.

4. The apparatus according to claim 2, further comprising: receiving an RRC reconfiguration message including conditional handover (CHO) configuration information associated with one or more candidate cells; Determining whether the selected candidate cell is configured with the CHO configuration information; and In response to the selected candidate cell being configured with the CHO configuration information, a CHO procedure to the selected candidate cell is performed.

5. The apparatus according to claim 2, further comprising: In response to the occurrence of the handover failure, radio link failure (RLF) report information is transmitted.

6. The apparatus of claim 5, wherein in response to the move command message including a voice fallback indication, the RLF report information includes an indicator for indicating that the handover procedure is for a voice fallback operation.

7. The apparatus of claim 5, wherein the method is performed by a user equipment (UE), wherein in response to the selected candidate cell being a UTRAN cell, the RLF report information is transmitted to a base station (BS) serving the UE, and wherein the BS forwards a message including the RLF report information to a source BS associated with the source NR cell.

8. The apparatus of claim 2, further comprising: In response to finding one or more candidate cells during the cell selection procedure and in response to at least one UTRAN cell being included in the one or more candidate cells, selecting the at least one UTRAN cell as the selected candidate cell.

Images