Method and mobile communication device for maintaining continuity of mobile communication

Abstract

A method of maintaining mobile communication continuity performed by a mobile communication device, the method comprising: starting a timer when the mobile communication device receives a service packet from a network or sends a service packet to a network; and detecting whether the network is reachable and whether a NAT mapping has changed when the mobile communication device does not receive a particular packet and the timer expires.

Description

[0001] Cross-references

[0002] This invention claims priority to U.S. Patent Application No. 17 / 677,344, filed on February 22, 2022, which is incorporated herein by reference. Technical Field

[0003] This invention generally relates to the field of wireless communication technology. More specifically, aspects of this invention relate to methods and mobile communication devices for maintaining the continuity of mobile communication. Background Technology

[0004] In a typical mobile communication environment, a user equipment (also known as a mobile station (MS)), such as a mobile phone (also known as a cell phone) or a tablet computer (PC) with wireless communication capabilities, can communicate voice and / or data signals with one or more serving networks. Communication between the UE and the mobile communication network can be performed using various Radio Access Technologies (RATs), including RATs specified by the Third Generation Partnership Project (3GPP) (referred to herein as 3GPP RATs) and RATs not specified by 3GPP (referred to herein as non-3GPP RATs).

[0005] Non-3GPP RATs include Wireless-Fidelity (Wi-Fi), Bluetooth (BT), and Zigbee technologies, while 3GPP RATs include Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Enhanced Data Rates for Global Evolution (EDGE), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access 2000 (CDMA2000), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), Time Division LTE (TD-LTE), LTE-Advanced (LTE-A), and New Radio (NR), among others. Specifically, GSM / GPRS / EDGE technology is also known as second-generation (2G) technology; WCDMA / CDMA-2000 / TD-SCDMA technology is also known as third-generation (3G) technology; LTE / LTE-A / TD-LTE technology is also known as fourth-generation (4G) technology; and NR technology is also known as fifth-generation (5G) technology.

[0006] Typically, a User Equipment (UE) may be in a Network Address Translation (NAT) environment provided by an untrusted non-3GPP access network (e.g., a Wi-Fi hotspot). The UE may access a 3GPP network through this untrusted non-3GPP access network. Figure 1A illustrates a UE in a NAT environment accessing a 3GPP network through an untrusted non-3GPP access network, where the public IP address of the untrusted non-3GPP access network is 26.85.198.101.

[0007] However, as shown in Figure 1B, when the public IP address of the untrusted non-3GPP access network changes from 26.85.198.101 to 26.85.1198.330 (e.g., when a smartphone is used as a Wi-Fi hotspot and mobile data is turned off and on) and the UE does not receive any notification that the public IP address has changed, the Internet Protocol Security (IPSec) tunnel between the UE and the evolved packet data gateway (ePDG) / non-3GPP interworking function (N3IWF) may not be usable because the external IP address of the IPSec tunnel is not updated on the ePDG / N3IWF.

[0008] When there is no 3GPP radio access network (RAN) that the UE can access or when the UE is in airplane mode, this may cause call drop in voice-over-WiFi (VoWiFi), non-access stratum (NAS) signaling failure, or other similar issues.

[0009] Therefore, a method and mobile communication device are needed to maintain the continuity of mobile communication in order to solve the above problems and achieve the goal of maintaining the continuity of mobile communication. Summary of the Invention

[0010] The following summary is illustrative only and is not intended to limit the scope in any way. That is, it is provided as an overview to introduce the concepts, highlights, benefits, and advantages of the novel and non-obvious techniques described herein. The detailed description below will further describe some, but not all, implementations. Therefore, the following summary is not intended to identify the essential features of the claimed subject matter, nor is it intended to determine the scope of the claimed subject matter.

[0011] Therefore, the main objective of this invention is to provide a method and mobile communication device for maintaining the continuity of mobile communication to overcome the above-mentioned disadvantages.

[0012] In one exemplary embodiment, a method for maintaining mobile communication continuity performed by a mobile communication device includes: starting a timer when the mobile communication device receives a service packet from or sends a service packet to the network; and detecting whether the network is reachable and whether the NAT mapping has changed when the mobile communication device fails to receive a specific packet and the timer expires.

[0013] In some embodiments, the period of the timer is less than the disconnection timeout period of the service corresponding to a specific group.

[0014] In some embodiments, the specific packet is a real-time transport protocol (RTP) packet, and the disconnection timeout is based on the RTP call interruption period.

[0015] In some embodiments, the specific packet is a real-time transport control protocol (RTCP) packet, and the disconnection timeout is based on the RTCP call interruption period.

[0016] In some embodiments, the specific packet is a Transmission Control Protocol Acknowledgment (TCP ACK) packet, and the disconnection timeout is the TCP timeout of the NAS signaling.

[0017] In some embodiments, the disconnection timeout period is preset by the mobile communication device or obtained in advance through communication with the network.

[0018] In some embodiments, the method further includes: in response to network reachability and the NAT mapping having changed, sending an update request message to the network to request an update of at least one of a public IP address and a user datagram protocol (UDP) port.

[0019] In some embodiments, detecting whether a NAT mapping has changed includes: sending a request message to the network to request a current hash value; after receiving the current hash value, comparing the current hash value with a hash value previously stored in the mobile communication device; and determining that the NAT mapping has changed when the current hash value is different from the previous hash value.

[0020] In some embodiments, the current hash value and the previous hash value are NAT detection (NATD) hash values.

[0021] In one exemplary embodiment, a mobile communication device for maintaining mobile communication continuity includes: a wireless transceiver configured to perform wireless transmission and reception with a network; and a controller coupled to the wireless transceiver and configured to: start a timer when the mobile communication device receives a service packet from the network or sends a service packet to the network; and detect whether the network is reachable and whether a NAT mapping has changed when the mobile communication device does not receive a specific packet and the timer expires. Attached Figure Description

[0022] A more complete understanding of the invention can be obtained by referring to the following detailed description and examples, in which:

[0023] Figure 1A is a schematic diagram showing a UE in a NAT environment accessing a 3GPP network through an untrusted non-3GPP access network.

[0024] Figure 1B is a schematic diagram illustrating why IPSec tunnels cannot be used when the public IP address of an untrusted non-3GPP access network changes.

[0025] Figure 2 This is a block diagram of a mobile communication environment described according to embodiments of the present invention.

[0026] Figure 3 This is a block diagram describing a mobile communication device according to an embodiment of the present invention.

[0027] Figure 4 This is a message sequence diagram illustrating an example process for maintaining mobile communication continuity between the UE, the untrusted non-3GPP access network, and the ePDG / N3IWF when the public IP address of the untrusted non-3GPP access network changes, as described in an embodiment of the present invention.

[0028] Figure 5 This is a message sequence diagram illustrating an example process for maintaining mobile communication continuity between the UE, the untrusted non-3GPP access network, and the ePDG / N3IWF when the public IP address of the untrusted non-3GPP access network changes, as described in an embodiment of the present invention.

[0029] Figure 6 This is a flowchart of a method for maintaining the continuity of mobile communication according to an embodiment of the present invention. Detailed Implementation

[0030] The following figures illustrate various aspects of the invention more fully. However, the invention can be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout the invention. Rather, these aspects are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Based on the teachings herein, those skilled in the art will understand that the scope of the invention is intended to cover any aspect disclosed herein, whether implemented independently of any other aspect of the invention or in combination with any other aspect of the invention. For example, an apparatus or method may be implemented using the various aspects set forth herein. Furthermore, the scope of the invention is intended to cover an apparatus or method implemented using a structure, function, or structure and function other than or different from the aspects disclosed herein. It should be understood that any aspect of the invention disclosed may be embodied by one or more elements of the claims.

[0031] The term “exemplary” as used herein means “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as superior to other aspects. Furthermore, in several figures, the same numbers denote the same elements, and “a” and “described” include plural references unless otherwise specified in the specification.

[0032] It should be understood that when a component is described as "connected" or "coupled" to another component, it can be directly connected or coupled to the other component, or there can be an intermediary component. Conversely, when a component is described as "directly connected" or "directly coupled" to another component, there is no intervening component. Other terms used to describe the relationship between components should be interpreted in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.).

[0033] Figure 2 This is a block diagram of a mobile communication environment 200 according to an embodiment of the present invention.

[0034] like Figure 2 As shown, the mobile communication environment 200 includes a UE 210, a NAT device 220, an untrusted non-3GPP access network 222, a non-3GPP interconnection gateway 230, and a 3GPP network 232.

[0035] UE 210 can be a feature phone, smartphone, personal computer (PC), laptop computer, machine-type communication (MTC) device, or any mobile communication device that supports the RAT used by untrusted non-3GPP access network 222 and 3GPP network 232. UE 210 can establish an IPsec tunnel with non-3GPP interoperability gateway 230 and can access 3GPP network 232 via the IPsec tunnel to obtain mobile services (e.g., voice and / or data services).

[0036] NAT device 220 is located between two different address domains and has two IP addresses associated with each of the two different address domains. Taking address translation between a public network and a private network as an example, NAT device 220 has a public IP address (referred to as the external IP address) that can be correctly routed in the public network and a private IP address (referred to as the internal IP address) that can be correctly routed in the private network. Specifically, NAT device 220 translates the private IP address currently used by UE 210 into a public IP address that can be routed within a public network (e.g., an untrusted non-3GPP access network 222). NAT device 200 can be any type of device configured to provide network address translation. For example, NAT device 220 can be a Wi-Fi access point (AP), a wireless router, etc.

[0037] The untrusted non-3GPP access network 222 is located outside the NAT device 220 that performs NAT and can be a wireless network using a RAT not specified by 3GPP. For example, depending on the RAT used, the untrusted non-3GPP access network 222 can be a Wi-Fi network or any future evolution of a Wi-Fi network, BT network, Zigbee network, WiMAX network, CDMA network, or fixed network (e.g., Digital Subscriber Line (DSL) network).

[0038] The non-3GPP interoperability gateway 230 is responsible for enabling interoperability between the untrusted non-3GPP access network 222 and the 3GPP network 232. Specifically, the non-3GPP interoperability gateway 230 can provide an IPsec tunnel between the UE 210 and the 3GPP network 232 via the untrusted non-3GPP access network 222 using the Internet Key Exchange version 2 (IKEv2) protocol. In one example, if the 3GPP network 232 is a 4G network, each non-3GPP interoperability gateway is an ePDG. In another example, if the 3GPP network 232 is a 5G network, each non-3GPP interoperability gateway is an N3IWF.

[0039] Depending on the RAT used, 3GPP network 232 can be a 4G network (e.g., LTE / LTE-A / TD-LTE network), a 5G network (e.g., NR network), or any further evolution of 5G networks. To further clarify, 3GPP network 232 may include an access network and a core network (not shown). The access network is responsible for processing radio signals, terminating radio protocols, and connecting UE 210 to the core network (if UE 210 chooses to access 3GPP network 232 via 3GPP access). The core network is responsible for performing mobility management, network-side authentication, and connecting to public / external data networks (e.g., the Internet and / or IP Multimedia Subsystem (IMS)).

[0040] In one example, if 3GPP network 232 is a 4G network, the access network can be an Evolved-UTRAN (E-UTRAN), and the core network can be an Evolved Packet Core (EPC). The E-UTRAN includes at least one evolved Node B (eNB), including a macro eNB, femto eNB, or pico eNB. The EPC includes at least a Home Subscriber Server (HSS), a Mobility Management Entity (MME), a Serving Gateway (S-GW), and a Packet Data Network Gateway (PDN-GW or P-GW).

[0041] In another example, if 3GPP network 232 is a 5G network, and the access network can be a Next Generation Radio Access Network (NG-RAN), the core network can be a Next Generation Core Network (NG-CN) (i.e., a 5G Core Network (5GC)). NG-RAN includes one or more gNBs. Each gNB further includes one or more Transmission Reception Points (TRPs), and each gNB or TRP can be referred to as a 5G cell forming one or more cells. Some gNB functions can be distributed across different TRPs, while others can be centralized, thus allowing for the flexibility and scope of specific deployments to meet the requirements of specific situations. NG-CN supports a variety of network functions, including Access and Mobility Function (AMF), Session Management Function (SMF), User Plane Function (UPF), Policy Control Function (PCF), Application Function (AF), and Authentication Server Function (AUSF). Each network function can be implemented as a network component on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an appropriate platform (e.g., cloud infrastructure).

[0042] Figure 3 This is a block diagram describing a mobile communication device 300 according to an embodiment of the present invention, wherein the mobile communication device 300 may refer to a UE (e.g., UE 210).

[0043] like Figure 3 As shown, UE 210 includes a wireless transceiver 310, a controller 320, a storage device 330, a display device 340, and an input / output (I / O) device 350.

[0044] The wireless transceiver 310 is configured to wirelessly transmit and receive data with the access networks of untrusted non-3GPP access networks 222 and / or 3GPP networks 232. Specifically, the wireless transceiver 310 includes a baseband processing device 311, an RF device 312, and an antenna 313, wherein the antenna 313 includes an antenna array for beamforming.

[0045] The baseband processing unit 311 is configured to perform baseband signal processing and control communication between the user identification card (not shown) and the RF device 312. The baseband processing unit 311 includes multiple hardware components that perform baseband signal processing, including analog-to-digital conversion (ADC) / digital-to-analog conversion (DAC), gain adjustment, modulation / demodulation, encoding / decoding, etc.

[0046] RF device 312 receives RF wireless signals via antenna 313, converts the received RF wireless signals into baseband signals for processing by baseband processing device 311, or receives baseband signals from baseband processing device 311, converts the received baseband signals into RF wireless signals, and then transmits them via antenna 313. RF device 312 also includes multiple hardware devices for performing radio frequency conversion. For example, RF device 312 includes a mixer for multiplying the baseband signal with a carrier oscillating in a cellular-enabled radio frequency, wherein, depending on the RAT used, the radio frequency can be 900 MHz, 2100 MHz, or 2.6 GHz used in 4G (e.g., LTE / LTE-A / TD-LTE) systems, or any radio frequency used in 5G (e.g., NR) systems (e.g., 30 GHz to 300 GHz for mmWave, or 3.3 GHz to 4.9 GHz for sub-6), or other radio frequencies.

[0047] The controller 320 may be a general-purpose processor, a microcontroller unit (MCU), an application processor, a digital signal processor (DSP), a graphics processing unit (GPU), a holographic processing unit (HPU), a neural processing unit (NPU), etc. It includes various circuits that provide multiple functions, such as data processing and calculation, controlling the wireless transceiver 310 to communicate wirelessly with the access network of the untrusted non-3GPP access network 222 and / or 3GPP network 232, storing and exporting data (e.g., program code) through the storage device 330, sending a series of frame data (e.g., representing text messages, graphics, images, etc.) to the display device 340, and receiving user input signals or output signals via the I / O device 350.

[0048] Specifically, the controller 320 coordinates the above-described operations of the wireless transceiver 310, storage device 330, display device 340, and I / O device 350 to execute the method proposed in this invention.

[0049] In another embodiment, the controller 320 may be incorporated into the baseband processing device 311 to serve as a baseband processor.

[0050] As those skilled in the art will understand, the circuitry of controller 320 typically includes transistors that control the operation of the circuitry as described herein. As will be further understood, the specific structure or interconnections of the transistors will typically be determined by a compiler, such as a Register Transfer Language (RTL) compiler. An RTL compiler can be operated by a processor on a script similar to assembly language code, compiling the script into a form suitable for final circuit layout or fabrication. Indeed, RTL is renowned for its role and use in facilitating the design process of electronic and digital systems.

[0051] Storage device 330 is a non-transitory machine-readable storage medium, including one or more Universal Integrated Circuit Cards (UICCs) (e.g., SIM / USIM), memory (e.g., FLASH memory or Non-Volatile Random Access Memory (NVRAM)), or Universal Integrated Circuit Cards (UICCs) (e.g., Subscriber Identification Module (SIM) or Universal SIM (USIM)), or magnetic storage devices (e.g., hard disk or magnetic tape), or any combination of data for storing applications (e.g., priority lists of ePDG / N3IWF information), instructions and / or program code, communication protocols (e.g., IKEv2 protocol and 4G / 5G protocol) and / or the methods proposed in this invention. In one example, the method of the present invention can be implemented as part of a 4G / 5G protocol, such as a 4G / 5G protocol stack, including a Non-Access Stratum (NAS) layer, an RRC layer for higher-layer configuration and control, a Packet Data Convergence Protocol / Radio Link Control (PDCP / RLC) layer, a Media Access Control (MAC) layer, and a Physical (PHY) layer.

[0052] The display device 340 may be a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, or an electronic paper display (EPD) for providing display functions. Alternatively, the display device 340 may further include one or more touch sensors disposed on or below it for sensing the touch, contact, or proximity of an object (such as a finger or stylus).

[0053] I / O device 350 includes one or more buttons, keyboard, mouse, touchpad, video camera, microphone and / or speaker, etc., used as a human-machine interface (MMI) for interacting with the user.

[0054] It should be understood that, Figure 3 The components described in the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. For example, a mobile communication device may include more components, such as a power supply and / or a Global Positioning System (GPS) device, wherein the power supply may be a mobile / replaceable battery that provides power to all other components of the mobile communication device (e.g., UE), and the GPS device may provide location information to the mobile communication device (e.g., UE) for certain location-based services or applications. Alternatively, a mobile communication device (e.g., UE) may include fewer components. For example, a mobile communication device (e.g., UE) may not include a display device 340 and / or an I / O device 350.

[0055] Figure 4 This is a message sequence diagram illustrating an example process for maintaining mobile communication continuity between the UE, the untrusted non-3GPP access network, and the ePDG / N3IWF when the public IP address of the untrusted non-3GPP access network changes, as described in an embodiment of the present invention.

[0056] In step S405, the UE establishes an IPsec connection with the ePDG / N3IWF through an IPsec tunnel to access the 3GPP network.

[0057] In step S410, when the UE receives a service packet from the 3GPP network or sends a service packet to the 3GPP network during the IPsec connection, the UE simultaneously starts timer T1.

[0058] In step S415, the public IP address of the untrusted non-3GPP access network is changed.

[0059] In step S420, the IPsec connection fails because the public IP address of the untrusted non-3GPP access network changes.

[0060] In step S425, when the UE does not receive a specific packet and timer T1 expires, the UE detects whether the 3GPP network is reachable and whether the NAT mapping has changed. The period of timer T1 is less than the disconnection timeout of the service corresponding to the specific packet. The disconnection timeout of the service is preset by the UE or obtained in advance through communication with the 3GPP network.

[0061] In step S430, in response to the change in the reachability of the 3GPP network and the NAT mapping, the UE sends an update request message to the 3GPP network to request an update of the public IP address, UDP port, or both.

[0062] In step S435, the IPsec connection is restored, and the UE can once again access the 3GPP network through the IPsec tunnel.

[0063] Figure 5 This is a message sequence diagram illustrating an example process for maintaining mobile communication continuity between a UE, an untrusted non-3GPP access network (such as a Wi-Fi hotspot), and an ePDG / N3IWF when the public IP address of an untrusted non-3GPP access network changes, as described in an embodiment of the present invention.

[0064] This can be achieved by using an extension of IKEv2 called the Mobility and Multihoming Protocol (MOBIKE). Figure 5 It facilitates message exchange between various devices. MOBIKE is a protocol that allows a UE to exchange messages without establishing a new IKE Security Association (SA) or IPsec SA when it moves, changes its IP address, or obtains a new IP address for multihoming.

[0065] In step S505, the UE establishes an IPsec connection with the ePDG / N3IWF through an IPsec tunnel to access the 3GPP network.

[0066] In step S510, when the UE receives a service packet from the 3GPP network or sends a service packet to the 3GPP network during the IPsec connection, the UE simultaneously starts timer Tn.

[0067] In step S515, the public IP address of the untrusted non-3GPP access network is changed.

[0068] In step S520, the IPsec connection fails because the public IP address of the untrusted non-3GPP access network changes.

[0069] In step S525, when the UE does not receive a specific packet and the timer Tn expires, the UE detects whether the 3GPP network is reachable and whether the NAT mapping has changed. The period of the timer Tn is less than the disconnection timeout of the service corresponding to the specific packet. The disconnection timeout of the service is preset by the UE or obtained in advance through communication with the 3GPP network.

[0070] Specifically, the UE can start different timers for different services. Here are some examples.

[0071] Example 1

[0072] When a UE operates a service such as VoWiFi in-call, the UE starts a timer T1 to determine whether an RTP packet is received from the 3GPP network within the time period of timer T1. The period of timer T1 is less than the disconnection timeout of the service corresponding to the RTP packet, and the disconnection timeout is the call interruption period that the 3GPP network waits for before interrupting communication based on RTP.

[0073] Example 2

[0074] When a UE operates a service such as VoWiFi hold-call, the UE starts a timer T2 to determine whether an RTCP packet is received from the 3GPP network within the time period of timer T2. The period of timer T2 is less than the disconnection timeout of the service corresponding to the RTCP packet, and the disconnection timeout is the call interruption period that the 3GPP network waits for before interrupting communication based on RTCP.

[0075] Example 3

[0076] After sending the NAS signaling packet, the UE starts timer T3 to determine whether a TCP ACK packet is received from the 3GPP network within the time period of timer T3. The period of timer T3 is less than the disconnection timeout, which is the TCP timeout of the NAS signaling.

[0077] In step S530, the UE sends an update request message (e.g., an IKEv2_INFORMATIONAL request) to the 3GPP network to request an update to the current hash value, where the current hash value may be a NATD hash value.

[0078] In step S535, the UE receives a response message containing the current hash value (e.g., an IKEv2_INFORMATIONAL response) from the 3GPP network.

[0079] In step S540, after receiving the current hash value, the UE compares the current hash value with the hash value previously stored in the UE, wherein the current hash value may be a NATD hash value.

[0080] In step S545, when the current hash value differs from the previous hash value, the UE determines that the NAT mapping has changed and executes the MOBIKE procedure to update the public IP address. Specifically, in step S5452 of the MOBIKE procedure, the UE can update its public IP address by sending an IKEv2_INFORMATIONAL request including an UPDATE_SA_ADDRESSES notification. The UE sends the IKEv2_INFORMATIONAL request using a new path with the new public IP address, where the new public IP address, translated from the local IP address by the untrusted non-3GPP access network, is used as the source address for the UE's outgoing services. Upon receiving the UPDATE_SA_ADDRESSES notification, the ePDG / N3IWF records the new public IP address and performs a return routability check on the new public IP address. When the check is complete, the ePDG / N3IWF returns an IKEv2_INFORMATIONAL response to the UE in step S5454 of the MOBIKE procedure and begins using the new public IP address as the destination address for the UE's outgoing services. In step S5456 of the MOBIKE procedure, the IPsec connection is restored, and the UE can once again access the 3GPP network through the IPsec tunnel.

[0081] Figure 6 This is a flowchart 600 of a method for maintaining the continuity of mobile communications according to an embodiment of the present invention, wherein the method can be applied to and performed by a communication connection to a mobile communication device (e.g., UE 110).

[0082] In step S605, when the mobile communication device receives a service packet from the network or sends a service packet to the network, the mobile communication device starts a timer, wherein the network is a 3GPP network other than the NAT device.

[0083] In step S610, when the mobile communication device does not receive a specific packet and the timer expires, the mobile communication device detects whether the network is reachable and whether the NAT mapping has changed. The period of the timer is less than the disconnection timeout of the service corresponding to the specific packet, and the disconnection timeout of the service is preset by the mobile communication device or obtained in advance through communication with the network.

[0084] As described above, when the public IP address of an untrusted non-3GPP access network changes, the UE can use the method and mobile communication device provided in this invention to maintain IPsec connection activity in order to avoid loss of service continuity.

[0085] It should be understood that any particular order or hierarchy of steps in any disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that a particular order or hierarchy of steps in the process may be rearranged while remaining within the scope of this invention. The appended method claims present the elements of the various steps in a sample order and are not intended to limit one to the particular order or hierarchy presented.

[0086] Ordinal terms such as "first" and "second" in claims modifying components do not imply any priority, precedence, or that one component is superior to another or that the order of execution of a method is higher. They are merely labels used to distinguish a component with a specific name from another component with the same name (except for the ordinal term).

[0087] Although the invention has been described by way of example and according to preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, the invention is intended to cover various modifications and similar arrangements (as will be apparent to those skilled in the art). Therefore, the scope of the appended patent application should be given the broadest interpretation to cover all such modifications and similar arrangements.

Claims

1. A method for maintaining mobile communication continuity, performed by a mobile communication device, the method comprising: The mobile communication device establishes an Internet Protocol secure connection with the Evolved Packet Data Gateway or non-3rd Generation Partner Program interoperability function through an Internet Protocol secure tunnel to access the 3rd Generation Partner Program network; When the mobile communication device receives a service packet from the network or sends a service packet to the network, a timer is started; as well as When the mobile communication device fails to receive a specific packet and the timer expires, it checks whether the network is reachable and whether the network address translation mapping has changed. Wherein, the period of the timer is less than the disconnection timeout time of the service corresponding to the specific group. The disconnection timeout is based on at least one of the following: the call interruption period of Real-Time Transport Protocol (RTP) packets, the call interruption period of Real-Time Transport Control Protocol (RTC) packets, and the RTP timeout of non-access stratum signaling.

2. The method for maintaining mobile communication continuity as described in claim 1, characterized in that, The specific packet is the Real-Time Transport Protocol (RTP) packet, and the disconnection timeout is the call interruption period based on the RTP packet.

3. The method for maintaining mobile communication continuity as described in claim 1, characterized in that, The specific packet is the Real-Time Transmission Control Protocol (RTP) packet, and the disconnection timeout is based on the call interruption period of the RTP packet.

4. The method for maintaining mobile communication continuity as described in claim 1, characterized in that, The specific packet is a Transmission Control Protocol (TCP) acknowledgment packet, and the disconnection timeout is the Real-Time Transmission Protocol (RTP) timeout for Non-Access Stratum (NAS) signaling.

5. The method for maintaining mobile communication continuity as described in claim 1, characterized in that, The disconnection timeout period is preset by the mobile communication device or obtained in advance through communication with the network.

6. The method for maintaining mobile communication continuity as described in claim 1, further comprising: In response to network reachability and a change in the network address translation mapping, an update request message is sent to the network to request an update of at least one of the public Internet Protocol address and User Datagram Protocol port.

7. The method for maintaining mobile communication continuity as described in claim 1, characterized in that, Detecting whether the network address translation mapping has changed includes: Send a request message to the network to request the current hash value; After receiving the current hash value, the current hash value is compared with a previous hash value stored in the mobile communication device; and When the current hash value is different from the previous hash value, it is determined that the network address translation mapping has changed.

8. The method for maintaining mobile communication continuity as described in claim 7, characterized in that, The current hash value and the previous hash value are network address translation detection hash values.

9. A mobile communication device for maintaining the continuity of mobile communication, comprising: A wireless transceiver is used to perform wireless sending and receiving with a network; as well as The controller, coupled to the wireless transceiver, is used for: Establish Internet Protocol (IP) secure connections to the 3G network by using Internet Protocol Secure Tunnels and Evolved Packet Data Gateways or non-3G Partner Program interoperability. When the mobile communication device receives a service packet from the network or sends a service packet to the network, a timer is started; as well as When the mobile communication device fails to receive a specific packet and the timer expires, it checks whether the network is reachable and whether the network address translation mapping has changed. Wherein, the period of the timer is less than the disconnection timeout time of the service corresponding to the specific group. The disconnection timeout is based on at least one of the following: the call interruption period of Real-Time Transport Protocol (RTP) packets, the call interruption period of Real-Time Transport Control Protocol (RTC) packets, and the RTP timeout of non-access stratum signaling.

10. The mobile communication device as described in claim 9, characterized in that, The specific packet is the Real-Time Transport Protocol (RTP) packet, and the disconnection timeout is the call interruption period based on the RTP packet.

11. The mobile communication device as described in claim 9, characterized in that, The specific packet is the Real-Time Transmission Control Protocol (RTP) packet, and the disconnection timeout is based on the call interruption period of the RTP packet.

12. The mobile communication device as described in claim 9, characterized in that, The specific packet is a Transmission Control Protocol (TCP) acknowledgment packet, and the disconnection timeout is the Real-Time Transmission Protocol (RTP) timeout for Non-Access Stratum (NAS) signaling.

13. The mobile communication device as described in claim 9, characterized in that, The disconnection timeout period is preset by the mobile communication device or obtained in advance through communication with the network.

14. The mobile communication device of claim 9, wherein the controller is further configured to: In response to network reachability and a change in the network address translation mapping, an update request message is sent to the network to request an update of at least one of the public Internet Protocol address and User Datagram Protocol port.

15. The mobile communication device as described in claim 9, characterized in that, Detecting whether the network address translation mapping has changed includes: Send a request message to the network to request the current hash value; After receiving the current hash value, the current hash value is compared with a previous hash value stored in the mobile communication device; and When the current hash value is different from the previous hash value, it is determined that the network address translation mapping has changed.

16. The mobile communication device as described in claim 15, characterized in that, The current hash value and the previous hash value are network address translation detection hash values.

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