RRC (Radio Resource Control) connection release message receiving and sending method, terminal and core network element

Abstract

The invention discloses an RRC connection release message receiving and sending method, a terminal and a core network element. The RRC connection release message receiving method comprises: a terminal receiving an RRC connection release message sent by a network element of a core network of an IoT NTN system, the RRC connection release message at least carrying a release reason field for indicating the terminal to perform circuit switched fallback and a redirection carrier field at least comprising carrier frequency point information of a target inter-system. The technical problem that an existing IoT NTN system does not support inter-system redirection and circuit switched fallback is solved.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a method for receiving and sending an RRC connection release message, a terminal, and a core network element. Background Art

[0002] Currently, the existing 3GPP standard protocol's definition of the RRC Connection Release message restricts the IoT NTN (Internet of Things - Narrowband Internet of Things, narrowband Internet of Things based on non - terrestrial networks) system's support for inter - system redirection and CSFB (Circuit Switched Fallback) functions. The main reasons are as follows:

[0003] (1) The ReleaseCause - NB - R13 cell carried in the RRC Connection Release - NB message defined in the 3GPP standard only supports values such as Load Balancing TAU (Track Area Updata) Required, RRC (Radio Resource Control) - Suspend, and other. These values are mainly for intra - system operations (such as tracking area updates triggered by load balancing, suspending connections, etc.), and no values related to supporting the CSFB function are defined.

[0004] (2) The RedirectedCarrierInfo - NB - R13 cell carried in the RRC Connection Release - NB message defined in the 3GPP standard only contains the E - UTRAN (Evloved Universal Terrestrial Radio Access Network) frequency information of the 4G standard, that is, CarrierFreq - NB - R13, which is mainly used to redirect the terminal to other cells or frequency bands of the same standard. However, for inter - system redirection, such as redirecting from the IoT NTN system to a 2G, 3G, or 5G standard system, frequency information of different standards is required, and the existing CarrierFreq - NB - R13 cell cannot provide such cross - standard frequency information.

[0005] In response to the above problems, no effective solution has been proposed yet. Summary of the Invention

[0006] The embodiments of the present application provide a method for receiving and sending RRC connection release messages, a terminal, and a core network element, so as to at least solve the technical problem that the existing IoT NTN system does not support inter-system redirection and circuit-switched fallback.

[0007] According to one aspect of the embodiments of the present application, a method for receiving an RRC connection release message is provided, including: receiving an RRC connection release message sent by a core network element of an IoT NTN system, where the RRC connection release message at least carries a release reason field for instructing the terminal to perform circuit-switched fallback and a redirection carrier field including at least carrier frequency point information of a target inter-system.

[0008] Optionally, receiving an RRC connection release message sent by a core network element of an IoT NTN system includes: sending an ESR message to the core network element of the IoT NTN system, where the ESR message at least carries a service type value indicating that the terminal falls back to the circuit domain of an inter-system to complete a voice service, and the core network element of the IoT NTN network is used to determine the release reason field and the redirection carrier field based on the ESR message, network status information, and pre-acquired terminal report information, and the terminal report information includes at least one of the following: the connection state of the terminal is an idle state, the network access capability of the terminal supports circuit-switched fallback, and the current location information of the terminal is the location information of the current cell where the terminal is located; receiving, through a radio interface, an RRC connection release message sent by a core network element of the IoT NTN system that at least carries the release reason field and the redirection carrier field.

[0009] Optionally, the inter-system includes: a first inter-system corresponding to the 2G system, a second inter-system corresponding to the 3G system, or a third inter-system corresponding to the 5G system.

[0010] Optionally, when the inter-system is the first inter-system, the redirection carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the frequency point offset; when the inter-system is the second inter-system, the redirection carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the band identifier, the downlink pilot time slot; when the inter-system is the third inter-system, the redirection carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the carrier bandwidth, the carrier frequency band, the subcarrier spacing of the synchronization signal block.

[0011] Optionally, after receiving the RRC connection release message sent by a core network element of the IoT NTN system, the method further includes: decoding the RRC connection release message to obtain the release reason field and the redirection carrier field; and based on the release reason field and the redirection carrier field, redirecting to a target inter-system that supports voice services in the circuit domain.

[0012] Optionally, according to the release reason field and the redirected carrier field, redirect to a target different system that supports voice services in the circuit domain, including: determining the target different system for redirection based on the release reason field and the preset terminal capability information; determining the target cell to be switched according to the carrier frequency point information of the target different system in the redirected carrier field; sending an RRC connection message to the target base station to which the target cell belongs, so as to fall back to the target different system that supports voice services in the circuit domain, where the RRC connection message is used to establish a circuit domain connection with the target different system.

[0013] According to one aspect of the embodiments of the present application, a method for sending an RRC connection release message is provided, including: sending an RRC connection release message to a terminal, where the RRC connection release message at least carries a release reason field for instructing the terminal to perform circuit domain fallback and a redirected carrier field including at least the carrier frequency point information of the target different system.

[0014] Optionally, sending an RRC connection release message to the terminal includes: receiving an ESR message sent by the terminal, where the ESR message at least carries a service type value indicating that the terminal falls back to the circuit domain of a different system to complete voice services; determining the release reason field and the redirected carrier field based on the ESR message, the network status information, and the pre-acquired terminal report information, where the terminal report information includes at least one of the following: the connection state of the terminal is the idle state, the network access capability of the terminal supports circuit domain fallback, and the current location information of the terminal is the location information of the current cell where the terminal is located; sending the RRC connection release message at least carrying the release reason field and the redirected carrier field to the terminal through the radio interface.

[0015] Optionally, the different system includes: a first different system corresponding to the 2G standard, a second different system corresponding to the 3G standard, or a third different system corresponding to the 5G standard.

[0016] Optionally, in the case where the different system is the first different system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the frequency offset; in the case where the different system is the second different system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the band identifier, the downlink pilot time slot; in the case where the different system is the third different system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the carrier bandwidth, the carrier frequency band, the subcarrier spacing of the synchronization signal block.

[0017] According to another aspect of the embodiments of the present application, a communication system is further provided. The system includes a core network element of the IoT NTN system and a terminal. Specifically: The core network element is configured to send an RRC connection release message to the terminal. The RRC connection release message at least includes a release reason field for indicating the terminal to perform circuit switched fallback, and a redirected carrier field at least including carrier frequency point information of the target heterogeneous system. The terminal is configured to decode the RRC connection release message to obtain the release reason field and the redirected carrier field, and redirect to the target heterogeneous system that supports voice services in the circuit domain according to the release reason field and the redirected carrier field.

[0018] According to another aspect of the embodiments of the present application, a terminal is further provided. The terminal includes a memory and a processor. The memory stores a computer program, and the processor is configured to execute the above-mentioned method for receiving an RRC connection release message through the computer program.

[0019] According to another aspect of the embodiments of the present application, a core network element is further provided. The terminal includes a memory and a processor. The memory stores a computer program, and the processor is configured to execute the above-mentioned method for sending an RRC connection release message through the computer program.

[0020] In the embodiments of the present application, the core network element of the IoT NTN system sends an RRC connection release message at least carrying a release reason field and a redirected carrier field to the terminal, enabling the terminal to perform heterogeneous system redirection according to network instructions, thereby significantly enhancing the functionality and flexibility of the IoT NTN system. Specifically, in the release reason field, an indication for the terminal to perform circuit switched fallback for voice services is added to solve the problem that the data network does not support or cannot provide real-time voice services. At the same time, carrier frequency point information of the heterogeneous system is added to the redirected carrier field to ensure that the terminal can quickly redirect from the data network to a network that supports voice services, avoiding long waits or call failures, and thus improving the user's communication experience and satisfaction. Generally speaking, the process of sending and receiving the RRC connection release message provided by the embodiments of the present application redirects the terminal with a demand for real-time voice services from the IoT NTN system (i.e., a data-intensive network) to the circuit domain, reducing the burden on the data network and optimizing the utilization efficiency of network resources, thereby solving the technical problem that the existing IoT NTN system does not support heterogeneous system redirection and circuit switched fallback. Description of the Drawings

[0021] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0022] Figure 1 It is a schematic structural diagram of an optional communication system according to an embodiment of the present application;

[0023] Figure 2 It is a schematic flowchart of a method for receiving an RRC connection release message according to an embodiment of the present application;

[0024] Figure 3 It is a schematic flowchart of a method for sending an RRC connection release message according to an embodiment of the present application;

[0025] Figure 4 It is a schematic diagram of an optional enhanced ReleaseCause-NB-R13 cell according to an embodiment of the present application;

[0026] Figure 5 It is a schematic diagram of an optional enhanced RedirectedCarrierInfo-NB-R13 cell according to an embodiment of the present application;

[0027] Figure 6 It is a schematic structural diagram of an optional terminal according to an embodiment of the present application;

[0028] Figure 7 It is a schematic structural diagram of an optional core network element according to an embodiment of the present application. Detailed implementation manners

[0029] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0030] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] To better understand the embodiments of the present application, the following is a translation and explanation of some nouns or terms that appear in the description process of the embodiments of the present application:

[0032] Radio Resource Control (RRC) connection: It is a control plane connection between a UE (User Equipment) and an eNodeB (Evolved NodeB, i.e., a Long-Term Evolution (LTE) base station) in a mobile communication system. It is mainly used to transmit high-layer signaling messages, such as operations like connection establishment, handover, and reconfiguration. Therefore, the RRC connection is an important control mechanism in LTE and 5G NR (New Radio) networks. Then, when the communication ends or the network needs to release resources, the eNodeB sends an RRC connection release message (RRC Connection Release) to the UE, and then the UE disconnects the connection with the network.

[0033] CDMA2000 (Code Division Multiple Access 2000): It is a 3G mobile communication standard, a radio interface recognized by the International Telecommunication Union's IMT-2000 standard, and also an extension of the 2G CDMAOne standard. It does not require new frequency band allocation and can operate stably in the existing PCS frequency band.

[0034] Global System for Mobile Communications (GSM): It is a digital mobile communication standard formulated by the European Telecommunications Standards Institute (ETSI).

[0035] Enhanced Data Rate for GSM Evolution (EDGE): It is a transitional technology from GSM to 3G. It mainly adopts a new modulation method in the GSM system, namely the state-of-the-art multi-slot operation and 8PSK (8 Phase Shift Keying) modulation technology. Among them, 8PSK can expand the signal space of the GMSK (Gaussian Filtered Minimum Shift Keying) modulation technology used in the existing GSM network from 2 to 8, so that the information contained in each symbol is 4 times that of the original.

[0036] Universal Mobile Telecommunications System (UMTS): It is a third-generation mobile phone technology that is currently the most widely adopted. Its radio interface uses W-CDMA (Wide Band Code Division Multiple Access) technology and is defined by the 3GPP standard.

[0037] UTRA (Universal Telecommunication System): It refers to the general term for the radio and network standards defined by 3GPP. In most cases, it only refers to WCDMA (Wideband Code Division Multiple Access).

[0038] HRPD (High Rate Packet Data), also known as 1xEVDO or HDR (High Data Rate): It is a high-speed wireless data technology based on CDMA (Code Division Multiple Access) invented by Qualcomm.

[0039] 1xRTT: It is a type of CDMA2000 that can provide a data transmission rate of up to 144 kbps and supports mobile IP addresses and always-on functionality. Its network structure includes a Packet Control Function (PCF) block and a Packet Data Service Node (PDSN). Among them, the Packet Control Function block mainly serves as an interface between the radio frequency part and the packet network (IP network); while the Packet Data Service Node serves as a foreign agent for mobile IP and has functions such as establishing, maintaining, and terminating the PPP (Point to Point Protocol) connection of mobile users, as well as authentication, authorization, and charging.

[0040] CSFB (Circuit Switched Fallback): It is a mobile phone technology that can provide good voice services for users in the early stage of the long-term evolution technology network development. Generally, there are two ways to implement Circuit Switched Fallback: the Handover method, which can achieve faster call establishment and shorter latency; and the Redirection method.

[0041] Absolute Radio Frequency Channel Number (ARFCN): It is a number used to identify the transmit and receive reference frequencies in a mobile communication system.

[0042] Carrier Wave: It refers to the waveform used to modulate the transmission signal, generally a sine wave. It is generally required that the frequency of the sine carrier be much higher than the bandwidth of the modulation signal, otherwise aliasing will occur and the transmission signal will be distorted.

[0043] Frequency: It refers to the specific absolute frequency value, generally the center frequency of the modulation signal.

[0044] Embodiment 1

[0045] The RRC Connection Release-NB message is a key signaling used to release the radio resource connection in the NB-IoT system. It is used to notify the terminal to release the current RRC connection and enter the idle state or the suspended state as needed. Currently, Section 6.7.2 of 3GPP 36.331 protocol describes the RRC Connection Release-NB message, which includes the following fields:

[0046] (1) CPB Index (CPB-Index): It is used to identify the index of the coverage-based paging configuration. Among them, the value 1 corresponds to the first entry in the CPB-ConfigList, and the value 2 corresponds to the second entry in the CPB-ConfigList of SystemInformationBlockType22-NB.

[0047] (2) DRB Continues to Use ROHC (Robust Header Compress): It is used to indicate whether to continue or reset the header compression protocol context of the DRB (Data Radio Bearer) configured with the header compression protocol. The existence of this field indicates that the header compression protocol context continues when the UE initiates UP-EDT (User Plane Early Data Transmission) in the same cell, while the non-existence indicates that the header compression protocol context is reset.

[0048] (3) Extended Wait Time (extendedWaitTime): It is used to indicate the time that the UE needs to wait after receiving the RRC Connection Release-NB message, so as to limit the UE from frequently attempting to access the network in a short period of time and causing unnecessary pressure on the network resources.

[0049] (4) Extended Wait Time - Control Plane Data (extendedWaitTime - CPdata): Used to indicate that after the UE receives the RRC Connection Release - NB message, so that after the control plane data transmission is completed, the UE immediately re - initiates a connection request, reducing unnecessary signaling interactions and power consumption.

[0050] (5) No Last Cell Update (noLastCellUpdate): Indicates that the last used cell should not be updated.

[0051] (6) Redirected Carrier Field (redirectedCarrierInfo): Used for cell selection when leaving the RRC connection to redirect the UE to switch to a specified NB - IoT carrier frequency. It contains relevant information for redirecting to other carriers, such as frequency, offset, etc.

[0052] (7) Dedicated Redirected Carrier Offset (redirectedCarrierOffsetDedicated): In the redirected carrier field, the dedicated offset provided for a specific frequency. Among them, for NB - IoT carrier frequencies, UEs supporting multi - band cells consider the redirected carrier offset dedicated to be common for all overlapping bands.

[0053] (8) Release Cause (releaseCause): Used to explain the reason for the RRC connection release message. Among them, if there is an extended wait time and / or if the UE is connected to the 5GC (5G Core), the E - UTRAN (i.e., the evolved universal terrestrial radio access network) should not set the releaseCause (a parameter used to indicate the radio resource release reason in the LTE network) to Load Balancing TAURequired.

[0054] (9) Resume Identity (resumeIdentity): Used to identify relevant information of the UE when resuming the RRC connection. Among them, the E - UTRAN configures ResulmeIdentity - R13 only when the UE is connected to the EPC, and configures ResulmeIdentity - R16 only when the UE is connected to the 5GC.

[0055] (10) T322 Timer (t322): A timer started by the UE after receiving the redirected carrier field. Its value is set according to the T322 value in the redirected carrier field. When the timer expires or stops, the UE discards the dedicated redirected carrier offset.

[0056] Therefore, the RRC Connection Release message does not carry values related to the CSFB function.

[0057] In addition, the CarrierFreq-NB-R13 cell carried in the RRC Connection Release message is usually used to indicate the frequency information to which the UE is redirected after releasing the RRC connection. Specifically, Section 6.7.3.2 of 3GPP 36.331 protocol describes the CarrierFreq-NB-r13 cell, which includes the following fields:

[0058] (1) Carrier frequency (carrierFreq): Represents the center frequency of the NB-IoT carrier.

[0059] (2) Carrier frequency offset (carrierFreqOffset): Represents the frequency offset relative to the anchored carrier, which is used for the frequency of the non-anchored carrier and can be a positive or negative offset.

[0060] Therefore, the RedirectedCarrierInfo-NB-r13 cell carried in the RRC Connection Release message only supports the EUTRA frequency information of the 4G system and does not support the frequency systems of other systems.

[0061] To solve the above problems, an embodiment of the present application first provides a communication system. Figure 1 It is a schematic structural diagram of a communication system provided according to an embodiment of the present application, as Figure 1 shown. The system includes: the core network element 11 of the IoT NTN system, the terminal 12, and the following interaction process can be carried out between the core network element 11 and the terminal 12 to create conditions for the IoT NTN system to support inter-system redirection and CSFB functions, including:

[0062] First, the core network element 11 sends an RRC connection release message to the terminal 12. Among them, the RRC connection release message at least carries a release reason field for indicating the terminal to perform circuit switched fallback and a redirected carrier field containing the carrier frequency information (including specific frequency bands and frequencies) of the target inter-system.

[0063] The terminal 12 decodes the received RRC connection release message to obtain the release reason field and the redirected carrier field, and redirects to the target inter-system that supports voice services in the circuit domain according to the release reason field and the redirected carrier field.

[0064] Next, the specific process of sending and receiving the RRC connection release message at both ends of the core network element 11 and the terminal 12 will be described in combination with specific embodiments.

[0065] First, an embodiment of the present application provides a method for receiving an RRC connection release message applied to a terminal 12. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0066] Figure 2 is a schematic flowchart of a method for receiving an RRC connection release message provided according to an embodiment of the present application. As Figure 2 shown, the method includes the following steps:

[0067] Step S202, receive a radio resource connection RRC connection release message sent by a core network element of the IoT NTN system.

[0068] Among them, the above RRC connection release message at least carries a release reason field for instructing the terminal to perform circuit domain fallback and a redirected carrier field at least including carrier frequency point information of the target heterogeneous system.

[0069] Specifically, before the terminal 12 receives the RRC connection release message, the terminal 12 can interact with the core network element 11 through the following process to determine whether to release the RRC connection of the terminal 12, including:

[0070] The first step: The terminal 12 sends an ESR (Extend Service Request) message to the core network element 11 of the IoT NTN system.

[0071] That is to say, when the terminal 12 needs to initiate a voice call or other circuit domain services, the terminal 12 can first send an ESR message to the core network element 11. Among them, the ESR message at least carries a service type value indicating that the terminal falls back to the circuit domain of the heterogeneous system, that is, the service type value carried in the ESR message is the MO CSFB reason value. For example: If the MO CSFB reason value is Mobile Originating CS fallback or 1xCSfallback, it means that when the terminal initiates a voice call in the LTE network, it falls back to the circuit domain of the 2 / 3G network to complete the voice call, or falls back to the CDMA1xRTT network.

[0072] The second step: The core network element 11 determines the release reason field and the redirected carrier field based on the ESR message, network status information, and pre-acquired terminal report information.

[0073] Among them, the terminal reporting information includes but is not limited to: the connection state of the terminal is the idle state, the network access capability of the terminal is to support circuit switched fallback, the current location information of the terminal is the location information of the current cell it is in, etc. The network state information includes but is not limited to: network load situation, network resource situation, network policies (including voice service priority), etc.

[0074] That is to say, the core network element 11 of the IoT NTN system makes the above decision on whether to allow the terminal 12 to perform CS Fallback. If allowed, the core network element 11 then decides on a target heterogeneous system that can provide circuit switched voice service for the terminal 12. Based on the core network element 11 allowing the terminal 12 to perform CS Fallback, a release cause field is generated, and the redirection field is filled with the carrier frequency point value of the target heterogeneous system.

[0075] Step 3: The core network element 11 sends an RRC connection release message carrying at least the release cause field and the redirected carrier field to the terminal 12 through the radio interface to instruct the terminal 12 to complete the fallback quickly.

[0076] Furthermore, after receiving the RRC connection release message sent by the core network element 11, the terminal 12 can also initiate heterogeneous system redirection through the following steps, including:

[0077] Step 1: The terminal 12 decodes the RRC connection release message to obtain the release cause field and the redirected carrier field.

[0078] Step 2: The terminal 12 redirects to the target heterogeneous system that supports voice services in the circuit domain according to the release cause field and the redirected carrier field.

[0079] In the technical solution provided in the above Step 2, the method can be implemented through the following steps: determine the target heterogeneous system for redirection based on the release cause field and the preset terminal capability information; determine the target cell to be switched according to the carrier frequency point information of the target heterogeneous system in the redirected carrier field; send an RRC connection message to the target base station to which the target cell belongs to fall back into the target heterogeneous system that supports voice services in the circuit domain, where the RRC connection message is used to establish a circuit domain connection with the target heterogeneous system.

[0080] Therefore, the above inter-system redirection process can be understood as follows. When the terminal 12 receives the RRC connection release message sent by the core network element 11, it will check the release reason field therein. If the release reason field is for circuit switched fallback, it indicates that the network instructs the terminal to fallback for circuit domain voice services. At this time, the terminal 12 can parse the redirected carrier field to obtain the carrier frequency point information of each inter-system, which is used to guide the terminal 12 to perform cell search and reselection. Then, the terminal 12 performs cell search based on the information in the redirected carrier field to find the cell with the best quality in the inter-system. Once found, the terminal 12 can perform cell selection or reselection to establish a connection with the target cell. Finally, after successfully establishing the connection, the terminal 12 can perform voice services within the circuit domain, that is, the terminal has been redirected to the target inter-system that supports circuit switched voice services and is ready to initiate or receive voice calls in this system.

[0081] In addition, the embodiment of the present application provides a method for sending an RRC connection release message of the core network element 11 applied to the IoT NTN system. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0082] Figure 3 It is a schematic flowchart of a method for receiving an RRC connection release message provided by an embodiment of the present application. As Figure 3 shown, the method includes the following steps:

[0083] Step S302, send an RRC connection release message to the terminal.

[0084] Among them, the above RRC connection release message carries at least a release reason field for instructing the terminal to perform circuit switched fallback and a redirected carrier field including at least the carrier frequency point information of the target inter-system.

[0085] Specifically, before the core network element 11 sends the RRC connection release message, it can judge whether to release the RRC connection of the terminal 12 and initiate inter-system redirection through the following interaction process with the terminal 12, including:

[0086] The first step: The core network element 11 receives the extended service request (ESR) message sent by the terminal 12.

[0087] That is to say, when the terminal 12 needs to initiate a voice call or other circuit domain services, the terminal 12 can first send an ESR (Extend Service Request) message to the core network element 11. The ESR message carries at least a service type value indicating that the terminal falls back to the circuit domain of a different system to complete the voice service. That is, the service type value carried in the ESR message is at least the MO CSFB cause value.

[0088] For example: If the MO CSFB cause value is Mobile Originating CS fallback or 1xCS fallback, it means that when the terminal initiates a voice call in the LTE network, it falls back to the circuit domain of the 2 / 3G network to complete the voice call, or falls back to the CDMA1xRTT network.

[0089] Step 2: The core network element 11 determines the release cause field and the redirected carrier field based on the ESR message, the network status information, and the pre-acquired terminal report information.

[0090] The terminal report information includes at least one of the following: the connection state of the terminal is the idle state, the network access capability of the terminal supports circuit domain fallback, and the current location information of the terminal is the location information of the current cell where it is located.

[0091] That is to say, the core network element 11 decides whether to allow the terminal 12 to perform CS Fallback based on the service type value in the ESR message and the terminal report information.

[0092] Step 3: The core network element 11 sends an RRC connection release message carrying at least the release cause field and the redirected carrier field to the terminal 12 through the radio interface to instruct the terminal 12 to quickly complete the fallback.

[0093] Therefore, by sending an RRC connection release message carrying at least a release cause field and a redirected carrier field from the core network element 11 to the terminal 12, the terminal 12 can perform inter-system redirection according to the network indication, thus significantly enhancing the functionality and flexibility of the IoT NTN system. Among them, cs-Fallback is added to the release cause field to clearly indicate that the terminal 12 performs circuit domain fallback for voice services, thereby solving the problem that the data network does not support or cannot provide real-time voice services; at the same time, the carrier frequency point information of the inter-system is added to the redirected carrier field, so as to ensure that the terminal 12 can quickly redirect from the data network to the network supporting voice services, avoiding long waiting or call failure, thereby improving the user's communication experience and satisfaction. Generally speaking, the process of sending and receiving the RRC connection release message provided by the embodiment of the present application redirects the terminal with a demand for real-time voice services from the IoT NTN system (i.e., data-intensive network) to the circuit domain, reducing the burden on the data network and optimizing the utilization efficiency of network resources.

[0094] In addition, regarding the above inter-system, its types include but are not limited to: the first inter-system corresponding to the 2G standard (such as Global System for Mobile Communications GMS, Enhanced Data Rate for GSM Evolution EDGE), the second inter-system corresponding to the 3G standard (such as Universal Mobile Telecommunications System UMTS, CDMA2000), the third inter-system corresponding to the 5G standard (such as the New Radio NR system of Release 15, the New Radio NR system of Release 17), etc. Among them:

[0095] When the inter-system is the first inter-system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the frequency offset.

[0096] When the inter-system is the second inter-system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the band identifier, the downlink pilot time slot.

[0097] When the inter-system is the third inter-system, the redirected carrier field includes at least one of the following: the carrier frequency point number of the system carrier, the carrier bandwidth, the carrier frequency band, the subcarrier spacing of the synchronization signal block.

[0098] Therefore, based on the above release cause field for indicating the terminal to perform circuit domain fallback, the ReleaseCause-NB-R13 cell defined in the existing 3GPP standard can be enhanced to obtain, for example Figure 4The obtained enhanced ReleaseCause-NB-R13 cell. The enhanced ReleaseCause-NB-R13 cell not only supports values such as LoadBalancing TAU (Track Area Updata), RRC-Suspend, and other, but also supports the release cause field of the circuit-switched fallback type.

[0099] In addition, based on the above redirection carrier field including at least the carrier frequency information of the target heterogeneous system, the existing CarrierFreq-NB-R13 cell defined in the 3GPP standard can be enhanced to obtain, for example, Figure 5 The obtained enhanced CarrierFreq-NB-R13 cell. The enhanced CarrierFreq-NB-R13 cell defines the frequency point information corresponding to systems of different standards. For example:

[0100] (1) For the 4G standard E-UTRA (Evolved Universal Terrestrial Radio Access) system, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the ARFCN-ValueEUTRA field, and this field is used to indicate the ARFCN value of the E-UTRA carrier.

[0101] (2) For the 2G standard G-ERAN (Global System for Mobile Communications GMS / Enhanced Data Rate for GSM Evolution EDGERadio Access Network) system, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierFreqsGERAN field, and this field is used to indicate the detailed information of the G-ERAN carrier frequency.

[0102] (3) For the FDD (Frequency Division Duplex) mode of the 3G standard WCDMA (Wideband Code Division Multiple Access) system, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the ARFCN-ValueUTRA field, and this field is used to indicate the ARFCN value of the carrier in the FDD mode.

[0103] (4) For the TDD (Time Division Duplex) mode of the WCDMA system in 3G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the ARFCN-ValueUTRA field, and this field is used to indicate the ARFCN value of the carrier in the TDD mode.

[0104] (5) For the HRPD (High Rate Packet Data) mode of the CDMA2000 system in 3G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierFreqsCDMA2000 field, and this field contains the frequency band type and the ARFCN value, and is used to indicate the carrier frequency in the HRPD mode.

[0105] (6) For the 1xRTT mode of the CDMA2000 system in 3G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierFreqsCDMA2000 field, and this field contains the frequency band type and the ARFCN value, and is used to indicate the carrier frequency in the 1xRTT mode.

[0106] (7) For the TDD mode (version 10) of the WCDMA system in 3G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierFreqsListUTRA-TDD-r10 field, and this field contains a list of multiple TDD carrier frequencies and is applicable to version R10.

[0107] (8) For the NR system (version 15) in 5G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierInfoNR-r15 field, and this field contains the detailed information of the NR carrier and is applicable to version R15.

[0108] (9) For the NR system (version 17) in 5G, the carrier information carried in the enhanced CarrierFreq-NB-R13 cell can be represented by the CarrierInfoNR-r17 field, and this field contains the detailed information of the NR carrier and is applicable to version R17.

[0109] It should be noted that the above Figure 5It is only by way of example to illustrate the specific form of carrying carrier frequency point information of different systems in the enhanced CarrierFreq-NB-R13 cell. The embodiments of the present application do not make specific limitations on the carrier frequency point information of different systems, and can be specifically set according to the actual application scenario.

[0110] Embodiment 2

[0111] According to the embodiments of the present application, there is also provided a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the method for receiving an RRC connection release message or the method for sending an RRC connection release message in Embodiment 1.

[0112] According to the embodiments of the present application, there is also provided a non-volatile storage medium, which includes a stored computer program. The device where the non-volatile storage medium is located executes the method for receiving an RRC connection release message or the method for sending an RRC connection release message in Embodiment 1 by running the computer program.

[0113] According to the embodiments of the present application, there is also provided a processor, which is used to run a computer program. When the computer program runs, it executes the method for receiving an RRC connection release message or the method for sending an RRC connection release message in Embodiment 1.

[0114] According to the embodiments of the present application, there is also provided a terminal, which includes: a memory and a processor. The memory stores a computer program, and the processor is configured to execute the method for receiving an RRC connection release message in Embodiment 1 through the computer program.

[0115] According to the embodiments of the present application, there is also provided a base station. The core network element includes: a memory and a processor. The memory stores a computer program, and the processor is configured to execute the method for sending an RRC connection release message in Embodiment 1 through the computer program.

[0116] Optionally, when the computer program runs, it executes the following steps: receiving an RRC connection release message sent by a core network element of an IoT NTN system, where the RRC connection release message at least carries a release reason field for indicating the terminal to perform circuit domain fallback and a redirected carrier field that at least includes the carrier frequency point information of the target heterogeneous system.

[0117] Optionally, when the computer program runs, it executes the following steps: sending an RRC connection release message to the terminal, where the RRC connection release message at least carries a release reason field for indicating the terminal to perform circuit domain fallback and a redirected carrier field that at least includes the carrier frequency point information of the target heterogeneous system.

[0118] As an alternative embodiment, the above terminal or base station may exist in the form of a mobile terminal, a computer terminal, or a similar computing device. Figure 6 and Figure 7 respectively show a hardware structure block diagram of a terminal for a method of receiving an RRC connection release message and a core network element for a method of sending an RRC connection release message. Among them, since Figure 6 and Figure 7 have the same architecture diagram, the specific structure of this hardware structure block diagram will be described below taking Figure 6 as an example. As shown in Figure 6 , the terminal 60 may include one or more (shown as 602a, 602b,..., 602n in the figure) processors 602 (the processor 602 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 604 for storing data, and a transmission device 606 for communication functions. In addition, it may further include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the BUS bus), a network interface, a power supply, and / or a camera. Those of ordinary skill in the art can understand that Figure 6 the structure shown is only schematic and does not limit the structure of the above terminal. For example, the terminal 60 may further include more or fewer components than those shown in Figure 6 , or have a different configuration from that shown in Figure 6 .

[0119] It should be noted that the above one or more processors 602 and / or other data processing circuits may generally be referred to as "data processing circuits" in this article. The data processing circuit may be embodied in whole or in part as software, hardware, firmware, or any combination thereof. In addition, the data processing circuit may be a single independent processing module, or be incorporated in whole or in part into any one of the other elements in the terminal 60. As involved in the embodiments of the present application, the data processing circuit is a processor control (such as the selection of a variable resistance terminal path connected to an interface).

[0120] The memory 604 can be used to store software programs and modules of application software, such as the program instructions / data storage devices corresponding to the [subject] method in the embodiments of the present application. The processor 602 executes various functional applications and data processing by running the software programs and modules stored in the memory 604, that is, implements the vulnerability detection method of the above application program. The memory 604 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some instances, the memory 604 may further include a memory remotely disposed relative to the processor 602, and these remote memories may be connected to the terminal 60 through a network. Examples of the above network include but are not limited to the Internet, enterprise intranet, local area network, mobile communication network, and combinations thereof.

[0121] The transmission device 606 is used to receive or send data via a network. Specific examples of the above network may include a wireless network provided by the communication provider of the terminal 60. In one instance, the transmission device 606 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station and thus can communicate with the Internet. In one instance, the transmission device 606 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0122] The display may be, for example, a touch-screen liquid crystal display (LCD), and the liquid crystal display enables a user to interact with the user interface of the terminal 60.

[0123] The above embodiment numbers are only for description and do not represent the advantages or disadvantages of the embodiments.

[0124] In the above embodiments of the present application, the descriptions of the respective embodiments have their own emphases. For parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0125] In several embodiments provided by the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only illustrative. For example, the division of units can be a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of units or modules can be in an electrical or other form.

[0126] The unit described as a separating component may or may not be physically separated, and the component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed over multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0127] In addition, each functional unit in various embodiments of the present application may be integrated in a processing unit, may be physically present separately for each unit, or two or more units may be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0128] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present application. The aforementioned storage medium includes: USB flash drives, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), mobile hard disks, magnetic disks, or optical disks, etc., which can store program codes.

[0129] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for receiving an RRC connection release message, characterized in that: include: A radio resource connection (RRC) connection release message sent by a core network element of a narrowband Internet of Things (IoT) NTN system based on a non-terrestrial network is received, wherein the RRC connection release message carries at least a release reason field for instructing the terminal to perform circuit domain fallback and a redirected carrier field including at least carrier frequency information of a target heterogeneous system.

2. The method according to claim 1, characterized in that Receive the RRC connection release message sent by the core network element of the IoT NTN system, including: Sending an extended service request ESR message to the core network element of the IoT NTN system, wherein the ESR message carries at least a service type value indicating that the terminal falls back to the circuit domain of the alien system to complete the voice service, and the core network element of the IoT NTN network is used to determine the release reason field and the redirection carrier field based on the ESR message, network status information and pre-acquired terminal report information, and the terminal report information includes at least one of the following: the connection state of the terminal is idle, the network access capability of the terminal is to support circuit domain fallback, and the current location information of the terminal is the location information of the current cell; The RRC connection release message carrying at least the release reason field and the redirected carrier field is received from the core network element of the IoT NTN system through a wireless interface.

3. The method according to claim 1, characterized in that The heterogeneous system includes: a first heterogeneous system corresponding to the 2G standard, a second heterogeneous system corresponding to the 3G standard, or a third heterogeneous system corresponding to the 5G standard.

4. The method according to claim 3, characterized in that In the case where the alien system is the first alien system, the redirected carrier field includes at least one of the following: a carrier frequency number and a frequency offset of a system carrier; In the case where the alien system is the second alien system, the redirected carrier field includes at least one of the following: a carrier frequency number, a frequency band identifier, and a downlink pilot time slot of a system carrier; In the case where the alien system is the third alien system, the redirected carrier field includes at least one of the following: a carrier frequency number of a system carrier, a carrier bandwidth, a carrier frequency band, and a subcarrier spacing of a synchronization signal block.

5. The method according to claim 1, characterized in that: After receiving the RRC connection release message sent by the core network element of the IoT NTN system, the method further includes: Decoding the RRC connection release message to obtain the release reason field and the redirection carrier field; According to the release reason field and the redirection carrier field, the signal is redirected to a target alien system that supports voice services in the circuit domain.

6. The method according to claim 5, characterized in that According to the release reason field and the redirection carrier field, redirecting to a target alien system supporting voice services in the circuit domain includes: Determine the target foreign system for redirection based on the release reason field and preset terminal capability information; Determine a target cell to be switched according to the carrier frequency information of the target heterogeneous system in the redirected carrier field; An RRC connection message is sent to a target base station to which the target cell belongs, so as to fall back to a target alien system that supports voice services in a circuit domain, wherein the RRC connection message is used to establish a circuit domain connection with the target alien system.

7. A method for sending an RRC connection release message, characterized in that: include: An RRC connection release message is sent to the terminal, wherein the RRC connection release message carries at least a release reason field for instructing the terminal to perform circuit domain fallback and a redirected carrier field including at least carrier frequency information of a target heterogeneous system.

8. The method according to claim 7, characterized in that Sending an RRC connection release message to the terminal includes: Receiving an ESR message sent by the terminal, wherein the ESR message carries at least a service type value indicating that the terminal falls back to a circuit domain of a different system to complete a voice service; Determine the release reason field and the redirection carrier field based on the ESR message, network status information, and pre-acquired terminal report information, wherein the terminal report information includes at least one of the following: the connection state of the terminal is an idle state, the network access capability of the terminal is to support circuit domain fallback, and the current location information of the terminal is the location information of the current cell; The RRC connection release message carrying at least the release reason field and the redirected carrier field is sent to the terminal through a wireless interface.

9. The method according to claim 7, characterized in that: The heterogeneous system includes: a first heterogeneous system corresponding to the 2G standard, a second heterogeneous system corresponding to the 3G standard, or a third heterogeneous system corresponding to the 5G standard.

10. The method according to claim 9, characterized in that In the case where the alien system is the first alien system, the redirected carrier field includes at least one of the following: a carrier frequency number and a frequency offset of a system carrier; In the case where the alien system is the second alien system, the redirected carrier field includes at least one of the following: a carrier frequency number, a frequency band identifier, and a downlink pilot time slot of a system carrier; In the case where the alien system is the third alien system, the redirected carrier field includes at least one of the following: a carrier frequency number of a system carrier, a carrier bandwidth, a carrier frequency band, and a subcarrier spacing of a synchronization signal block.

11. A communication system, characterized in that: The communication system includes: core network elements and terminals of the IoT NTN system, wherein: The core network element is used to send an RRC connection release message to the terminal, wherein the RRC connection release message includes at least: a release reason field for instructing the terminal to perform circuit domain fallback, and a redirected carrier field including at least carrier frequency information of a target heterogeneous system; The terminal is used to decode the RRC connection release message to obtain the release reason field and the redirection carrier field; and redirect to a target alien system that supports voice services in the circuit domain according to the release reason field and the redirection carrier field.

12. A terminal, characterized in that: include: A memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to execute the method for receiving an RRC connection release message according to any one of claims 1 to 6 through the computer program.

13. A core network element, characterized in that: include: A memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the method for sending an RRC connection release message according to any one of claims 7 to 10 through the computer program.

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