Method for preventing triggering inter-RAT change and communication device thereof

Abstract

The present invention discloses a method for preventing triggering a change between wireless access technologies and a communication device thereof, wherein the communication device communicates with at least one cellular network. The communication device comprises: a radio transceiver for sending or receiving a wireless radio frequency signal to or from a cellular network; and a processor for receiving an incoming call request for triggering a circuit switched fallback process or an evolved packet system fallback process from the cellular network via the radio transceiver, for asking a user to accept or reject the incoming call request before triggering the circuit switched fallback process or the evolved packet system fallback process, and for determining whether to trigger the circuit switched fallback process or the evolved packet system fallback process based on the user's response to the inquiry. The method for preventing triggering a change between wireless access technologies and the communication device thereof provided by the present invention can prevent the communication device from accidentally disconnecting.

Description

Technical Field

[0001] The present invention relates to a communication method. In particular, the present invention relates to a method for preventing triggering of an inter-RAT change, thereby avoiding accidental disconnection. Background Art

[0002] The term "wireless" generally refers to electrical or electronic operations that are implemented without the use of "hard-wired" connections. "Wireless communication" is the transmission of information over a distance without the use of electrical conductors or wires. The distance can be short (e.g., a few meters for a television remote) or long (e.g., thousands or tens of thousands of kilometers for radio communications). The best-known example of wireless communication is the cellular phone. A cellular phone uses radio waves to allow a user to call another party in another part of the world. The cellular phone can be used anywhere as long as there is a cellular phone site covering the equipment that sends and receives the signals, which are processed into voice and data for transmission between cellular phones.

[0003] There are various well-developed and well-defined cellular communication technologies. For example, the Global System for Mobile Communications (GSM) is a well-defined and universal communication system that uses time division multiplexing (TDMA) technology and is a multiplexing scheme for digital radio to send voice, data and signaling data (e.g., dialing phone numbers) between mobile phones and cell sites. CDMA2000 is a hybrid mobile communication 2.5G / 3G (generation) technology standard that uses code division multiple access (CDMA) technology. The Universal Mobile Telecommunications System (UMTS) is a 3G mobile communication system that provides an enhanced range of multimedia services over the GSM system. Wireless Fidelity (Wi-Fi) is a technology defined by the 802.11 engineering standard for home networking, mobile phones, and video games, providing high-frequency wireless local area networks. Long Term Evolution (LTE) is a wireless communication standard for high-speed data for mobile phones and data terminals. LTE is based on GSM / EDGE and UMTS / HSPA network technologies, and improves capabilities and speeds by using different radio interfaces and core network improvements.

[0004] In order to provide more effective communication services and improve user experience, a method for preventing accidental disconnection of a communication device is urgently needed. Summary of the invention

[0005] In view of this, the present invention discloses a method for preventing triggering of inter-RT change and a communication device thereof.

[0006] According to an embodiment of the present invention, a communication device is provided, wherein the communication device communicates with at least one cellular network, and the communication device includes a radio transceiver and a processor. The radio transceiver is used to send or receive radio frequency signals to or from an air interface in the cellular network; and the processor is used to determine whether to trigger a change between radio access technologies in a subsequent process when the communication device is in a connection mode. When the processor determines that a change process between radio access technologies will be triggered, the processor is configured to selectively execute a predetermined process to replace the subsequent process, thereby avoiding the change between radio access technologies.

[0007] According to another embodiment of the present invention, a method for preventing triggering a change between wireless access technologies is provided, wherein a communication device is in a connection mode, and the method comprises: when the communication device is in the connection mode, determining whether to trigger the change between wireless access technologies in a subsequent process; and when it is determined that the change between wireless access technologies will be triggered in the subsequent process, selectively executing a predetermined process to replace the subsequent process, thereby avoiding the change between wireless access technologies.

[0008] According to another embodiment of the present invention, a method for preventing triggering a change between wireless access technologies is provided, wherein a communication device is in a connection mode, the method comprising: determining whether the communication device is in the connection mode; and when the communication device is in the connection mode, selectively executing a predetermined process to prevent the change between wireless access technologies.

[0009] The method for preventing triggering of change between wireless access technologies and the communication device thereof provided by the present invention can avoid accidental disconnection of the communication device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is an exemplary block diagram of a communication device described according to an embodiment of the present invention;

[0011] Figure 2 is an exemplary block diagram of a modem described according to an embodiment of the present invention;

[0012] Figure 3A is an example deployment of a cellular communication system described according to an embodiment of the present invention;

[0013] Figure 3B is another exemplary deployment of a cellular communication system described according to another embodiment of the present invention;

[0014] Figure 4A is a flow chart of a method for preventing triggering an inter-RAT change when a communication device is in a connected mode according to an embodiment of the present invention;

[0015] Figure 4Bis a flow chart of a method for preventing triggering an inter-RAT change when a communication device is in a connected mode according to another embodiment of the present invention;

[0016] Figure 5A is an example message flow of rejecting an incoming CS service request described in the first embodiment of the first aspect of the present invention;

[0017] Figure 5B is another example message flow of ignoring an incoming CS service request according to the second embodiment of the first aspect of the present invention;

[0018] Figure 6 It is the traditional message flow from E-UTRAN to UTRAN or GERAN;

[0019] Fig. 7A is an example message flow described according to the second embodiment of the second aspect of the present invention;

[0020] Figure 7B is an example message flow for triggering RRC connection reestablishment;

[0021] Figure 8 is an example message flow described according to an embodiment of the third aspect of the present invention;

[0022] Fig. 9 The following is an example message flow for ignoring an incoming call notification message according to an embodiment of the fourth aspect of the present invention. DETAILED DESCRIPTION

[0023] Certain words are used in the specification and claims to refer to specific components. It should be understood by those skilled in the art that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but rather use differences in the functions of the components as the criteria for distinction. The term "including" mentioned throughout the specification and claims is an open-ended term and should be interpreted as "including but not limited to". In addition, the term "coupled" herein includes any direct and indirect electrical connection means. Therefore, if the text describes a first device coupled to a second device, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices or connection means.

[0024] The following description is the best embodiment of the present invention, which is for the purpose of describing the principle of the present invention and is not intended to limit the present invention. It is understood that the embodiments of the present invention can be implemented by software, hardware, firmware or any combination thereof.

[0025] Figure 1is an example block diagram of a communication device described according to an embodiment of the present invention. The communication device 100 may be a portable electronic device, for example, a mobile station (MS, which may be replaced by a user equipment (UE)). The communication device 100 may include at least an antenna module (having at least one antenna), a radio transceiver 110, a modem 120, an application processor 130, a user identification card 140, and a storage device 150. The radio transceiver 110 may use an antenna module to receive a wireless radio frequency signal through an air interface, use the antenna module to send the wireless radio frequency signal to the air interface, and perform RF signal processing. For example, the radio transceiver 110 may convert the received signal into an intermediate frequency (IF) signal or a baseband signal to be processed, or receive an IF or baseband signal from the modem 120 and convert the received signal into a wireless radio frequency signal to be sent to a network device of a cellular network. According to an embodiment of the present invention, the network device may be a cell, a node B, an evolved node B (eNB), a g node B (gNB), a base station, a mobility management entity (Mobility Management Entity, MME), etc. on the network side of a cellular network, and communicates with the communication device 100 through wireless radio frequency signals.

[0026] The radio transceiver 110 may include a plurality of hardware to perform radio frequency conversion and RF signal processing. For example, the radio transceiver 110 may include a power amplifier for amplifying the RF signal, a filter for filtering out unwanted portions of the RF signal, and / or a mixer for performing RF conversion. According to an embodiment of the present invention, the radio frequency may be, for example, 900 MHz or 1800 MHz for GSM, 1900 MHz for UMTS, any specific frequency band frequency for a CDMA2000 system, any specific frequency band frequency for an LTE system, or any specific frequency band frequency for a 5G new radio (NR) system.

[0027] The modem 120 may be a cellular communication modem configured to process cellular system communication protocol operations and process IF or baseband signals from or to the radio transceiver 110. The application processor 130 is configured to run an operating system of the communication device 100 and to run application programs installed in the communication device 100. In an embodiment of the present invention, the modem 120 and the application processor 130 may be designed as discrete chips having a bus or hardware interface coupled to each other, or they may be integrated into a joint chip (i.e., a system on a chip), but the present invention is not limited thereto.

[0028] The subscriber identity card 140 may be a SIM, USIM, R-UIM, CSIM card or similar card, and generally includes user account information, International Mobile Subscriber Identity (IMSI) and SIM Application Toolbox (SAT) command set. In addition, the subscriber identity card 140 may provide storage space for phone book contacts. The storage device 150 may be coupled to the modem 120 and the application processor 130, and may store system data or user data.

[0029] It is worth noting that in order to clarify the concept of the present invention, Figure 1 is a schematic block diagram showing only the components related to the present invention. For example, in some embodiments of the present invention, the communication device may further include Figure 1 Peripheral devices not shown. In another example, in the embodiment of the present invention, the communication device may further include a central controller coupled to the modem 120 and the application processor 130. Therefore, the present invention is not limited to Figure 1 The content shown.

[0030] In the embodiment of the present invention, Figure 1 As shown, the communication device can support multiple radio access technologies (RAT) communications through a single card structure. It is worth noting that although Figure 1 Single card applications are shown, but the present invention is not limited thereto. For example, in an embodiment of the present invention, a communication device may include multiple user identification cards to support multi-RAT communication in single standby or multi-standby mode. In multi-RAT communication applications, the user identification cards may share modems, radio transceivers and / or antenna modules, and may have the ability to process different cellular system operations and process corresponding RF, IF or baseband signals, wherein the above processing capabilities follow the corresponding cellular system communication protocols.

[0031] In addition, those skilled in the art can still make various changes and modifications based on the above description to obtain a communication device including multiple radio transceivers and / or multiple antenna modules that supports multi-RAT wireless communication without departing from the scope and spirit of the present invention. Therefore, in the embodiment of the present invention, through certain changes and modifications, the communication device can be designed to support multi-card applications in single standby or multi-standby mode.

[0032] It is further worth noting that the user identification card 140 can be a dedicated hardware card as described above, or in the embodiment of the present invention, there is a separate identifier, number, address or the like burned into the internal storage device of the corresponding modem and can identify the communication device. Therefore, the present invention is not limited to the content shown in the figure.

[0033] It is further worth noting that, in the embodiment of the present invention, the communication device may further support multiple IMSIs.

[0034] Figure 2 is an exemplary block diagram of a modem according to an embodiment of the present invention. The modem 220 may be Figure 1 The modem 120 shown in the figure may include at least a baseband processing device 221, a processor 222, an internal storage device 223 and a network card 224. The baseband processing device 221 may receive an IF or baseband signal from the radio transceiver 110 and perform IF or baseband signal processing. For example, the baseband processing device 221 may convert the IF or baseband signal into a plurality of digital signals and process the digital signals, and vice versa. The baseband processing device 221 may include a plurality of hardware devices that perform signal processing, wherein the plurality of hardware devices may be exemplified by an analog-to-digital converter for ADC conversion, a digital-to-analog converter for DAC conversion, an amplifier for gain adjustment, a modulator for signal modulation, a demodulator for signal demodulation, an encoder for signal encoding, a decoder for signal decoding, and the like.

[0035] According to an embodiment of the present invention, the baseband processing device 221 may be designed to have the ability to process baseband signal processing operations of different cellular systems and to process corresponding IF or baseband signals, thereby supporting multi-RAT wireless communications, wherein the above processing capabilities comply with the corresponding cellular system communication protocols. According to another embodiment of the present invention, the baseband processing device 221 may include a plurality of subunits, wherein each subunit may be designed to have the ability to process baseband signal processing operations of one or more specific cellular systems and to process corresponding IF or baseband signals, thereby supporting multi-RAT wireless communications, wherein the above processing capabilities comply with the corresponding cellular system communication protocols. Therefore, the present invention is not limited to any specific implementation.

[0036] The processor 222 may control the operation of the modem 220. According to an embodiment of the present invention, the processor 222 may be arranged to execute the program code of the corresponding software module of the modem 220. The processor 222 may maintain and execute individual tasks, threads and / or protocol stacks of different software modules. In a preferred embodiment, a protocol stack may be applied to process the radio behavior of one RAT respectively. However, it is also possible to apply multiple protocol stacks to process the radio behavior of multiple RATs simultaneously, and the present invention should not be limited thereto.

[0037] The processor 222 can also read data from a user identification card (e.g., user identification card 140) coupled to the modem, and write data into the user identification card. The internal storage device 223 can store system data and user data of the modem. The processor 222 can also access the content storage device 223.

[0038] The network card 224 provides Internet access services for the communication device. Figure 2 The network card shown is configured inside the modem, but the present invention is not limited to this. In an embodiment of the present invention, the communication device may also include a network card configured outside the modem, or the communication device may also be coupled to an external network card for providing Internet access services. In an embodiment of the present invention, the network card 224 may be a virtual network card different from a physical card, wherein the virtual network card is generated by the operating system of the communication device 100. Therefore, the present invention is not limited to any specific implementation method.

[0039] It is worth noting that, in order to clarify the concept of the present invention, Figure 2 An example block diagram is shown with only elements relevant to the present invention. Therefore, the present invention is not limited to Figure 2 The content shown.

[0040] It is further worth noting that in embodiments of the present invention, the modem may also include multiple processors and / or multiple baseband processing devices. For example, the modem may include multiple processors and / or multiple baseband processing devices to support multi-RAT operations. Therefore, the present invention is not limited to Figure 2 The content shown.

[0041] It is further worth noting that in the embodiment of the present invention, the baseband processing device 221 and the processor 222 may be integrated into one processing unit, and the modem may include one or more of the above processing units to support multi-RAT operation. Figure 2 The content shown.

[0042] Figure 3A It is an example deployment of a cellular communication system described according to an embodiment of the present invention. The cellular communication system 300A is a 3GPP system that supports one or more wireless networks of one or more RATs, such as a 5G system, a 4G / LTE system, a 3G system, and a 2G system. The cellular communication system 300A has one or more fixed base facility units, such as wireless communication stations 302, 303, 304, and 305, to form a wireless network distributed in a geographical area. The base unit may also be referred to as an access point, an access terminal, a base station, a Node-B, an eNode-B, a gNode-B, or other terms used in the art, such as the eNode-B (eNB) (e.g., 302) of the 4G / LTE system, the Node-B (e.g., 303) of the 3G system, the base station (BS) (e.g., 304) of the 2G system, and the gNode-B (gNB) (e.g., 305) of the 5G system shown in the figure. Each wireless communication station 302, 303, 304, 305 serves a geographical range.

[0043] The eNB 302, Node-B 303, BS 304 and / or gNB 305 may serve a communication device / user equipment (UE) 301 in the cellular communication system 300A. The communication device 301 may be implemented as Figure 1 The communication device 100 shown. The communication device 301 can establish a bearer with the cellular communication system 300A. For example, the communication device 301 can establish an EPS bearer in a 4G system through an S1 interface, or establish a packet data protocol (PDP) context in a 3G system through an lu interface, establish a PDP context in a 2G system through a Gb interface, or establish a new radio (NR) bearer in a 5G system.

[0044] Figure 3B is another example deployment of a cellular communication system described according to another embodiment of the present invention. Cellular communication system 300B is another system that supports one or more wireless networks of one or more RATs, such as 4G / LTE system and CDMA2000 system. Cellular communication system 300B has one or more fixed base facility units, such as wireless communication stations 306 and 307. Wireless communication stations 306 and 307 that form a wireless network distributed in a geographical area may be referred to as access points, access terminals, base stations, Node-Bs, eNode-Bs, or other terms used in the art, such as the eNode-B (eNB) (e.g., 306) of the 4G / LTE system and the base station (BS) (e.g., 307) of the CDMA 2000 system shown in the figure. Each wireless communication station 306, 307 serves a geographical range.

[0045] The eNB 306 and BS 307 may serve a communication device / user equipment (UE) 308 in the cellular communication system 300B. The communication device 301 may be implemented as Figure 1 The communication device 100 is shown. The communication device 301 can establish a bearer with the cellular communication system 300B.

[0046] When a communication system supporting multiple RATs serves a communication device (e.g., communication device 100) 301 or 308, in many cases, the communication device may need to perform a RAT change (or an inter-RAT change, an inter-RAT bearer change). However, the inter-RAT change often causes unexpected disconnection, affecting the user experience. The user experience will be worse when the user is performing a very important specific operation. For example, when the user is playing an online game, the user will find that disconnection is unacceptable.

[0047] In view of this, the present invention provides a method for preventing a communication device from triggering an inter-RAT change, especially when the communication device is in a connected mode, such as an Evolved Packet System (EPS) Mobility Management (EMM) connection mode or a fifth generation mobile communication (5G) Mobility Management (MM) connection mode.

[0048] Figure 4A 4 is a flowchart of a method for preventing triggering an inter-RAT change when a communication device is in a connected mode according to an embodiment of the present invention. The method begins when a processor (e.g., processor 222 of modem 120 / 220 or application processor 130) of a communication device (e.g., communication device 100, 301, or 308) determines whether the communication device is operating in a connected mode or a connected state. When the processor determines that the communication device is in a connected mode (connected state) (step S402), the processor may selectively execute a predetermined process to prevent triggering an inter-RAT change (step S404). In the example, when the processor determines that the communication device is in a connected mode (connected state), the processor may directly execute a predetermined process to prevent triggering an inter-RAT change.

[0049] According to an embodiment of the present invention, the connection mode (connection state) is an EMM connection mode (EMM connection state). When a radio resource control (RRC) connection between a communication device and a network device (e.g., a mobile management entity MME) has been established, the communication device starts to operate in the EMM connection mode or enters the EMM connection state. Typically, the modem 120 / 220 knows whether the communication device is in the EMM connection mode (EMM connection state) by checking the communication state. For a UE in the ECM-CONNECTED state, there is a signaling connection between the UE and the MME, wherein ECM-CONNECTED and ECM-IDLE correspond to the EMM-CONNECTED and EMM-IDLE modes defined in TS24.301, respectively. For the definition of the EMM-connection state, reference may be made to Chapter 4.6 of 3GPPTS 23.401 and 3GPP TS 24.301.

[0050] According to another embodiment of the present invention, the connection mode (connection state) is a 5GMM connection mode (5GMM connection state). Generally, when there is an N1 NAS signaling connection between the UE and the network via non-3GPP access, the UE is in 5GMM-CONNECTED mode. The term 5GMM-CONNECTED mode via non-3GPP access used in this document corresponds to the term CMCONNECTED for non-3GPP access used in 3GPP TS 23.501 [8]. For the definition of 5GMM-connection state, reference may be made to 3GPP TS124 501.

[0051] Figure 4B 4 is a flowchart of a method for preventing triggering an inter-RAT change when a communication device is in a connected mode according to another embodiment of the present invention. The method begins when a processor (e.g., processor 222 of modem 120 / 220 or application processor 130) of a communication device (e.g., communication device 100, 301, or 308) determines whether the communication device is operating in a connected mode or a connected state. In an embodiment of the present invention, the connection mode (connection state) may be the above-mentioned EMM connection mode (EMM connection state) or 5GMM connection mode (5GMM connection state). When the processor determines that the communication device is in a connected mode (connection state) (step S406), the processor may further determine whether a change between radio access technologies (RATs) will be triggered in a subsequent process (step S408). In an embodiment of the present invention, when the communication device enters a connected state or when it is detected that a subsequent process that will trigger an inter-RAT change may occur, the processor executes step S408. When it is determined that the inter-RAT change process will be triggered or the inter-RAT change process may be triggered in a subsequent process, the processor may selectively execute a predetermined process instead of a subsequent process to prevent the inter-RAT change from being triggered (step S410). When it is determined that the inter-RAT change process will not be triggered in a subsequent process, the processor may determine to execute a subsequent process (step S412).

[0052] In the embodiment of the present invention, for different scenarios or possibly triggering different subsequent processes, the predetermined processes executed by the processor may be different.

[0053] In the first aspect of the present invention, when the communication device is in EMM connection mode (EMM connection state) and receives an incoming CS service request from a network device of a cellular network, the processor may know that if the communication device receives the incoming CS service request, a subsequent process, such as a circuit switch fall back (CSFB) process, will be triggered. When the CSFB process is triggered, the network device (e.g., MME) will send a handover command to the communication device. When the CSFB process is involved, the communication device must trigger a handover process, which is an inter-RAT change process, so that the communication device reconnects / releases from the LTE network to the traditional 2G / 3G network for CS services (e.g., making a voice call).

[0054] Therefore, in the first aspect of the present invention, in order to prevent triggering an inter-RAT change, when the communication device is in an EMM connection mode (EMM connection state) and receives an incoming circuit switched (CS) service request from a network device of a cellular network, the processor may send a message to reject the incoming CS service request message, or ignore the incoming CS service request message without sending any response message to the network device.

[0055] Figure 5A This is an example message flow for rejecting an incoming CS service request according to the first embodiment of the first aspect of the present invention. In this embodiment, upon receiving a CS service notification message, such as a paging message, from the MME, the processor of the communication device may reply to a NAS extended service request, wherein the CSFB response field may be set to 0, thereby rejecting the CS service request. Upon receiving a NAS extended service request with a CSFB response field of 0, the MME will further send a CS paging rejection notification message to the Mobile Switching Center (MSC) to notify the rejection of the CS service request. In this case, the CSFB process will not be triggered or executed, and the inter-RAT change process will not be triggered or executed. For details on mobile terminal calls in activation mode, reference may be made to Section 7.3 of 3GPP TS 23.272.

[0056] Figure 5B This is an example message flow for ignoring an incoming CS service request according to the second embodiment of the first aspect of the present invention. In this embodiment, once a CS service notification message is received from the MME, the processor of the communication device may directly ignore the message without sending any response message to the MME. In this case, the CSFB process will not be triggered or executed, and the inter-RAT change process will not be triggered or executed.

[0057] In the embodiment of the present invention, the processor that determines whether to reject or ignore the CS service request may be the processor 222 of the modem 120 / 220 or the application processor 130. In addition, the rejection or ignoring determination step may be generated by request (i.e., determined independently for each request), by application (e.g., the determination for each request depends on the application currently executed by the user), or by default (i.e., as long as a CS service request is received when the communication device is in EMM connection mode, the CS service request is always rejected or ignored).

[0058] More specifically, when the design makes a decision by request, when a CS service request is received in EMM connection mode, a pop-up message will be displayed on the display screen of the communication device. The pop-up message can assist the user in deciding whether to accept the CS service request. If the user decides that responding to the CS service request is more important than other things, the user decides to accept the CS service request. If the user does not want to be disturbed at present, the user may decide not to receive the CS service request. When the user decides not to receive the CS service request, the processor may reject or ignore the CS service request as described above. An example implementation is that the processor 222 of the modem 120 / 220 may notify the application processor 130 that a CS service request is received in EMM connection mode, and the application processor 130 may pop up a message to ask the user.

[0059] When the design makes decisions through applications, user options are provided to the user to decide which applications should not be disturbed, for example, by any other application or incoming CS service request. For example, the user can set a do not disturb state for his preferred application (e.g., online games). In this case, when a CS service request is received in EMM connection mode during the activation of the application, the processor will, as described above, reject or ignore the CS service request without further notifying the user. An example implementation is that the processor 222 of the modem 120 / 220 can notify the application processor 130 that the CS service request is received in the EMM connection mode, and the application processor 130 can decide which application is currently activated and decide whether to reject or ignore the CS service request based on the user options or user preferences of the corresponding application. Another example implementation is that the application processor 130 sends a command to the processor 222 of the modem 120 / 220 to notify that the user does not want to be disturbed during the activation of the application. In this case, when a CS service request is received in the EMM connection mode during this period, the processor 222 of the modem 120 / 220 can decide to reject or ignore the CS service request.

[0060] When the design makes a decision by default, a user option is provided to the user to decide whether to reject all incoming CS service requests under certain conditions or in a preset time period. When the condition is met or in a preset time period, the processor will reject or ignore the CS service request as described above without notifying the user. An example implementation is that the processor 222 of the modem 120 / 220 notifies the application processor 130 that the CS service request is received in the EMM connection mode, and the application processor 130 determines whether the condition is met or whether it is now in a preset time period. If the answer is yes, the application processor 130 notifies the processor 222 of the modem 120 / 220 to reject or ignore the CS service request. Another example implementation is that the application processor 130 sends a command to the processor 222 of the modem 120 / 220 to notify that the preset condition is met or it is now in a preset time period, thereby rejecting all incoming CS service requests. In this case, when a CS service request is received in the EMM connection mode during the time period, the processor 222 of the modem 120 / 220 may decide to reject or ignore the CS service request.

[0061] For the second aspect of the present invention, when the communication device is in the EMM connection mode (EMM connection state), the processor may know that when a cellular packet switch (PS) call (e.g., a long-term evolution voice call) has been established but the signal quality of the cellular PS call is poor (e.g., degraded to a certain level), there is an opportunity to trigger a subsequent process (e.g., single radio voice call continuity, SRVCC). When the SRVCC process is triggered, the network device (e.g., MME) will send a handover command to the communication device. When the SRVCC process is involved, the handover process is an inter-RAT change process, so that the communication device reconnects / releases from the LTE network to the traditional 2G / 3G network to maintain the voice call.

[0062] Figure 6 This is the traditional message flow of SRVCC from E-UTRAN to UTRAN or GERAN. Figure 6 For detailed description, please refer to Figure 4.2.2-1 in 3GPP TS 23.216. Figure 6 As shown, in the conventional design, the last step is to perform a handover operation in response to receiving a handover command from the MME. Therefore, performing a handover operation is a UE behavior defined by the 3GPP standard.

[0063] However, as described above, the execution of the handover process will cause the communication device to leave the LTE network and disconnect. Therefore, in the second aspect of the present invention, in order to prevent the triggering of the inter-RAT change, when the communication device is in the EMM connection mode (EMM connection state) or when the communication device is in the EMM connection mode (EMM connection state) and a cellular packet switching call (e.g., LTE voice call) has been established, the processor may selectively execute a parameter update process to notify the cellular network that the SRVCC service is not supported, or selectively execute an RRC connection reestablishment process instead of a handover process, thereby responding to the handover command received from the network device and reestablishing the RRC connection with the 4G / LTE cellular network.

[0064] According to a first embodiment of the second aspect of the present invention, the application processor 130 sends a command with the CISRVCC parameter set to 0, thereby instructing the processor 222 of the modem 120 / 220 to selectively perform a parameter update process to update the modem performance. By setting the CISRVCC parameter to 0, the communication device notifies the cellular network that it does not support the SRVCC service. In this case, even if the signal quality of the cellular PS call degrades to a certain level, the network device will not trigger SRVCC. For details of the command for setting the parameter CISRVCC, reference may be made to 3GPP TS 27.007 subclause 8.63.

[0065] In an embodiment of the present invention, the determination of whether to prohibit SRVCC service can be generated by the call (i.e., determined independently for each cellular PS call), by the application (e.g., depending on the application currently executed by the user), or by default (i.e., as long as the communication device is in EMM connection mode, the modem 120 / 220 will notify the cellular network that SRVCC service is not supported).

[0066] More specifically, when the design makes decisions by calling, a pop-up message may be displayed on the display screen of the communication device when a cellular PS call is established. The pop-up message may assist the user in deciding whether to disable SRVCC service for the cellular PS call. If the user decides that keeping the PS call is more important than other things, the user decides not to disable SRVCC service. If the user does not currently want to reconnect to the traditional network, the user may decide to disable SRVCC service. When the user decides to disable SRVCC service, the modem 120 / 220 will notify the cellular network that SRVCC service is not supported. An example implementation is that the application processor 130 sends a command to the processor 222 of the modem 120 / 220 to set the CISRVCC parameters based on the user selection.

[0067] When the design makes decisions by application, a user option is provided to the user to decide which applications should not be disturbed or affected by the SRVCC service. For example, a user may set a do not disturb state for a preferred application (e.g., online gaming). In this case, when the do not disturb application is activated, the SRVCC service should be disabled. An example implementation is that when the application processor 130 detects that the do not disturb application is activated, the application processor 130 sends a command with the CISRVCC parameter set to 0 to the processor 222 of the modem 120 / 220, thereby instructing the processor 222 to selectively perform the above-mentioned parameter update process.

[0068] When the design makes a decision by default, a user option is provided to the user to decide whether to disable the SRVCC service under certain conditions or in a preset time period, for example, each time the communication device enters the EMM connection state. When the condition is met or in the preset time period, the processor will disable the SRVCC service as described above without notifying the user. An example implementation is that when the application processor 130 detects that the condition is met or is now in the predetermined time period, the application processor 130 sends a command with the CISRVCC parameter set to 0 to the processor 222 of the modem 120 / / 220, thereby instructing the processor 222 to selectively perform the above parameter update process.

[0069] According to a second embodiment of the second aspect of the present invention, when a cellular packet switch (PS) call (e.g., a long term evolution voice call) has been established while the communication device is in EMM connection mode (EMM connection state), the processor may selectively execute an RRC connection reestablishment process instead of a switching process in response to receiving a switching command from a network device, and reestablish the RRC connection with the 4G / LTE cellular network.

[0070] Fig. 7A is an example message flow described according to the second embodiment of the second aspect of the present invention. Figure 6 In the second embodiment of the second aspect of the present invention, the communication device (e.g., UE) selectively performs an RRC connection reestablishment process instead of a handover process in response to a handover command received from the MME. For details of the RRC connection reestablishment, reference may be made to 3GPP TS 36.331 and TS 23.216. It can be understood that, as Figure 7B As shown (refer to Figure 5.4.3.1-2 of 3GPP TS36.331), since the handover command is a command in the MobilityFromEUTRACommand command set that can trigger the RRC connection reestablishment process, executing the RRC connection reestablishment process instead of the handover process is an allowed behavior for the cellular network.

[0071] Through the RRC connection reestablishment process, the communication device reestablishes the RRC connection with the 4G / LTE cellular network, thereby not triggering the non-execution of the handover operation and not triggering the non-execution of the inter-RAT change process.

[0072] In the embodiment of the present invention, the processor that determines to execute the RRC connection reestablishment process may be the processor 222 of the modem 120 / 220 or the application processor 130. In addition, the determination to selectively execute the RRC connection reestablishment process may be generated by a request (i.e., independently determined for each SRVCC handover request), generated by an application (e.g., determined for each SRVCC handover request depending on the application currently executed by the user), or generated by default (i.e., as long as an SRVCC handover request is received when the communication device is in the EMM connection mode, the RRC connection reestablishment process will always be executed).

[0073] More specifically, when the design makes a decision by request, a pop-up message is displayed on the display screen of the communication device when an SRVCC handover request is received. The pop-up message can assist the user in deciding whether to reject the SRVCC handover request. If the user decides that keeping the PS call is more important than other things, the user decides not to reject the SRVCC handover request. If the user does not currently want to reconnect to the traditional network, the user may decide to reject the SRVCC handover request. When the user decides to reject the SRVCC handover request, the modem 120 / 220 triggers the RRC connection reestablishment process as described above. An example implementation is that the application processor 130 sends a command to the processor 222 of the modem 120 / 220 based on the user selection to instruct the processor 222 whether to trigger a handover process or RRC connection reestablishment in response to the SRVCC handover request.

[0074] When the design makes decisions through applications, a user option is provided to the user to decide which applications should not be disturbed or affected by the SRVCC service. For example, a user may set a do not disturb state for their preferred applications (e.g., online games). In this case, when the do not disturb application is activated, the SRVCC switching request should be rejected. An example implementation is that the processor 222 of the modem 120 / / 220 notifies the application processor 130 that an SRVCC switching request is received in the EMM connection mode, and the application processor 130 may determine which application is currently activated and whether to reject the SRVCC switching request based on the user option of the user preference of the corresponding application. Another example implementation is that the application processor 130 may send a command to the processor 222 of the modem 120 / 220 to notify that the user does not want to be disturbed during the time period when the application is activated. In this case, when an SRVCC switching request is received in the EMM connection mode during the time period, the processor 222 of the modem 120 / 220 may decide to perform RRC connection reconstruction in response to the above-mentioned SRVCC switching request.

[0075] When the design makes a decision by default, a user option is provided to the user to decide whether to reject the SRVCC handover request under certain conditions or within a preset time period, for example, each time the communication device enters the EMM connection state. When the SRVCC handover request is received when the condition is met or within the preset time period, the processor will reject the SRVCC handover request as described above without notifying the user. An example implementation is that when it is detected that the condition is met or the predetermined time period is now, the processor 222 of the modem 120 / 220 may decide to perform RRC connection reestablishment in response to the above-mentioned SRVCC handover request.

[0076] In a third aspect of the present invention, in order to prevent triggering an inter-RAT change, when the communication device is in an EMM connection mode (EMM connection state), the processor may selectively execute a deregistration process to deregister from the cellular network. The reason for executing the deregistration process is to prevent a subsequent process, wherein the subsequent process has a chance to trigger an inter-RAT change process. In the third aspect of the present invention, the subsequent process may be exemplified by a periodic or aperiodic re-registration process to re-register with the cellular network, an incoming call or SMS processing process to process an incoming CS service request, or other processes.

[0077] refer to Figure 3B When the communication device is in the cellular communication system 300B, the communication device is usually registered in the LTE network and the CDMA2000 network. When the communication device is in the EMM connection mode (EMM connection state), the communication device still monitors the CDMA2000 network to avoid missing any incoming voice calls or SMS messages. In addition, the communication device can also use an interval period to perform a periodic or aperiodic re-registration process. However, performing a periodic or aperiodic re-registration process to re-register the CDMA 2000 network, or processing an incoming CS service request will cause the communication device to temporarily leave the LTE network (e.g., suspend LTE service) to connect to the CDMA2000 network (for details, refer to CDMA 2000 standard C.S0005), which is also an inter-RAT change process. When the communication device supports single radio LTE (SRLTE) and is in the EMM connection mode (EMM connection state), the inter-RAT change process is particularly unwelcome because the RRC connection will be ported. Therefore, in the third aspect of the present invention, in order to prevent the inter-RAT change from being triggered, when the communication device is in the EMM connected mode (EMM connected state), the processor may execute a deregistration process to deregister from the CDMA2000 network.

[0078] Figure 8 is an example message flow described according to the third aspect of the present invention. According to an embodiment of the third aspect of the present invention, a communication device is configured to send a registration message to deregister (or remove registration) from a CDMA 2000 network, wherein the REG_TYPE column is set to "0011" in the registration message. The registration type code "0011" means "power interruption" (for more details, refer to CDMA 2000 standard C.S0005 table 2.7.1.3.2.1-1). Upon receiving the registration message, the base station replies with a sequential message (confirmation message) to notify the communication device that the deregistration has been successful. In this case, the CDMA 2000 network will not provide services to the communication device, and will not trigger an inter-RAT change during the time period when the communication device is deregistered from the network.

[0079] In an embodiment of the present invention, the decision whether to log out from the cellular network may be made by the application (e.g., depending on the application currently executed by the user) or by default (i.e., the modem 120 / 220 will perform the logout process as long as the communication device is in EMM connected mode).

[0080] In more detail, when the design is determined by the application, a user option is provided to the user to decide which applications should not be disturbed or affected by the communication services provided by a specific RAT (e.g., the above-mentioned CDMA 2000). For example, a user can set a do not disturb state for his or her preferred application (e.g., an online game). In this case, when the do not disturb application is activated, a deregistration process should be performed. An example implementation is that when the application processor 130 detects that the do not disturb application is activated, the application processor 130 sends a command to the processor 222 of the modem 120 / 220, thereby instructing the processor 222 to perform the above-mentioned deregistration process to deregister the communication device from the corresponding cellular network.

[0081] When the design is determined by default, a user option is provided to the user to decide whether to deregister from a specific cellular network under certain conditions or within a preset time period, for example, each time the communication device enters the EMM connection state. When the condition is met or within the preset time period, the processor will perform the deregistration process as described above without notifying the user. An example implementation is that when the application processor 130 detects that the condition is met or is now within the predetermined time period, the application processor 130 sends a command to the processor 222 of the modem 120 / 220, thereby instructing the processor 222 to perform the above-mentioned deregistration process to deregister the communication device from the corresponding cellular network.

[0082] In a fourth aspect of the present invention, in order to prevent triggering an inter-RAT change, when a communication device capable of providing 5G NR services and communicating with a 5G core network is in a 5G MM connection mode (5G MM connection state) and receives an incoming call notification message from a network device of a cellular network, the processor may reject the incoming call notification message. For example, one method for the processor to reject the incoming call notification message is that the processor ignores the incoming call notification message without sending any response message to the network device.

[0083] Typically, when a communication device is connected to a 5G stand-alone (SA) network and communicates with a network device providing communication services in the 5G SA network, and the communication device or the network device in the 5G SA network does not support voice over new radio (VoNR), if the communication device receives an incoming call notification message in a 5GMM connection mode (5GMM connection state) and decides to receive the incoming call, an inter-RAT change will be triggered.

[0084] In more detail, when the communication device is in 5GMM connection mode (5GMM connection state) and receives an incoming call notification message (e.g., a session initialization protocol invite message for an IMS call), since VoNR in the 5G network cannot be established between the communication device and the network device, the processor may know that if the communication device accepts the incoming call request, a subsequent process, such as an EPS fallback (EPS FB) process, will be triggered. When the EPS FB process is triggered, the communication device will reconnect / release from the 5G network to the traditional LTE network to handle the incoming call (e.g., make a voice call).

[0085] Therefore, in the fourth aspect of the present invention, in order to prevent triggering an inter-RAT change, when the communication device is in a 5GMM connection mode (5GMM connection state) and receives an incoming call notification message from a network device of a cellular network, if it is determined that VoNR cannot be implemented, the processor may ignore the incoming call notification message without sending any reply message to the network device, reject the incoming call notification message, thereby avoiding triggering the EPS FB process.

[0086] According to an embodiment of the present invention, the processor may do nothing with the incoming call notification message and wait until the time expires (for example, wait until a predetermined timer for processing the incoming call notification message specified by the corresponding standard expires). When the predetermined timer expires, the network device regards the incoming call request as rejected and does not perform subsequent processes to establish the call.

[0087] Fig. 9 This is an example message flow of ignoring an incoming call notification message according to an embodiment of the fourth aspect of the present invention. In this embodiment, upon receiving an incoming call notification message from a gNB, for example, a SIP invite message for an IMS call, the processor of the communication device will ignore the message without sending any reply message to the gNB. In this case, the non-execution of the EPS FB process is not triggered, and the non-execution of the inter-RAT change process is not triggered.

[0088] In an embodiment of the present invention, the processor that decides to ignore the incoming call notification message may be the processor 222 of the modem 120 / 220 or the application processor 130. In addition, the determination of the ignoring process may be generated by request (i.e., determined independently for each request), generated by an application (e.g., determined for each request depending on the application currently executed by the user), or generated by default (i.e., as long as the incoming call notification message is received when the communication device connected to the 5G SA network is in the 5GEMM connection mode, the incoming call notification message will always be ignored).

[0089] More specifically, when the design makes a decision by request, when an incoming call notification message is received in 5GMM connection mode, a pop-up message will be displayed on the display screen of the communication device. The pop-up message can assist the user in deciding whether to accept the incoming call. If the user decides that responding to the incoming call is more important than other things, the user decides to accept the incoming call. If the user does not want to be disturbed at the moment, the user may decide not to accept the incoming call. When the user decides not to accept the incoming call, the processor may reject or ignore the incoming call as described above. An example implementation is that the processor 222 of the modem 120 / 220 may notify the application processor 130 that an incoming call notification is received in 5GMM connection mode, and the application processor 130 may pop up a message to ask the user.

[0090] When the design makes decisions through applications, user options are provided to the user to decide which applications should not be disturbed, for example, by any other application or incoming call request. For example, the user can set a do not disturb state for his preferred application (e.g., online game). In this case, when an incoming call notification is received in 5GMM connection mode during activation of the do not disturb application, the processor will reject or ignore the incoming call notification as described above without notifying the user. An example implementation is that the processor 222 of the modem 120 / / 220 notifies the application processor 130 that an incoming call notification is received in 5GMM connection mode, and the application processor 130 can determine which application is currently activated and whether to reject or ignore the incoming call notification based on the user's preference of the corresponding application. Another example implementation is that the application processor 130 can send a command to the processor 222 of the modem 120 / 220 to notify that the user does not want to be disturbed during the time period when the application is activated. In this case, when an incoming call notification is received in 5GMM connection mode during this time period, the processor 222 of the modem 120 / 220 can decide to reject or ignore the incoming call.

[0091] When the design makes a decision by default, a user option is provided to the user to decide whether to reject all incoming calls under certain conditions or in a preset time period. When the condition is met or in a preset time period, the processor will reject or ignore the incoming call as described above without notifying the user. An example implementation is that the processor 222 of the modem 120 / 220 notifies the application processor 130 that an incoming call notification is received in the 5GMM connection mode, and the application processor 130 determines whether the condition is met or whether it is now in a preset time period. If the answer is yes, the application processor 130 notifies the processor 222 of the modem 120 / 220 to reject or ignore the incoming call. Another example implementation is that the application processor 130 sends a command to the processor 222 of the modem 120 / 220 to notify that the preset condition is met or it is now in a preset time period, thereby rejecting all incoming calls. In this case, when an incoming call notification is received in the 5GMM connection mode during the time period, the processor 222 of the modem 120 / 220 may decide to reject or ignore the incoming call notification.

[0092] According to the above embodiment, when the communication device is in the connection mode or when the processor determines to trigger the inter-RAT change process in the connection mode, the predetermined process is selectively executed to prevent the inter-RAT change from being triggered. In this case, no accidental disconnection occurs, and the user experience is greatly improved.

[0093] The present invention may be implemented in other specific forms without departing from the spirit or essential features of the present invention. The described examples are considered to be illustrative in all aspects and are not limiting. Therefore, the scope of the present invention is indicated by the claims rather than the foregoing description. All changes in the methods and scopes of the equivalent claims are within the scope of the present invention.

Claims

1. A communication device, in a connection mode, comprising: a radio transceiver for transmitting or receiving radio frequency signals to or from a cellular network; and A processor is used to receive an incoming call request triggering a circuit switched fallback process or an evolved packet system fallback process from the cellular network via the radio transceiver, to inquire a user to accept or reject the incoming call request before triggering the circuit switched fallback process or the evolved packet system fallback process, and to determine whether to trigger the circuit switched fallback process or the evolved packet system fallback process based on the user's response to the inquiry.

2. The communication device according to claim 1, wherein: The step of determining whether to trigger the circuit switched fallback process or the evolved packet system fallback process based on the user's response to the inquiry includes: based on the response indicating that the user rejects the incoming call request, rejecting or ignoring the incoming call request, thereby avoiding triggering the circuit switched fallback process or the evolved packet system fallback process.

3. The communication device according to claim 2, wherein: The processor is further configured to execute: based on the response indicating that the user rejects the incoming call request, sending a message indicating rejection of the incoming call request to the cellular network to reject the incoming call request.

4. The communication device according to claim 3, characterized in that This message is a non-access layer extended service request with the circuit switched fallback response field set to 0.

5. The communication device according to claim 2, wherein: The processor is further configured to perform: based on the response indicating that the user rejects the incoming call request, rejecting the incoming call request by ignoring the incoming call request.

6. The communication device according to claim 5, characterized in that The step of ignoring the incoming call request is performed by preventing the communication device from sending any response message of the incoming call request to the cellular network.

7. The communication device according to claim 1, wherein: The incoming call request is a session initiation protocol invite message for an IP multimedia subsystem call, wherein the incoming call request is received when the communication device is in a fifth generation mobile management connection mode.

8. A method for preventing triggering of an inter-radio access technology change, comprising: An incoming call request for triggering a circuit switched fallback process or an evolved packet system fallback process is received from a cellular network through a communication device, wherein: The communication device is in a connecting mode; Before triggering the circuit switched fallback process or the evolved packet system fallback process, asking the user via the communication device to accept or reject the incoming call request; and Through the communication device, based on the response of the user to the inquiry, it is determined whether to trigger the circuit switched fallback process or the evolved packet system fallback process.

9. The method for preventing triggering of a change between radio access technologies according to claim 8, characterized in that: The step of determining whether to trigger the circuit switched fallback process or the evolved packet system fallback process based on the user's response to the inquiry includes: based on the response indicating that the user rejects the incoming call request, rejecting or ignoring the incoming call request, thereby avoiding triggering the circuit switched fallback process or the evolved packet system fallback process.

10. The method for preventing triggering of a change between radio access technologies according to claim 9, characterized in that: The method further includes: sending, by the communication device, a message indicating rejection of the incoming call request to the cellular network based on the response indicating that the user rejects the incoming call request, so as to reject the incoming call request.

11. The method for preventing triggering of a change between radio access technologies according to claim 10, characterized in that: This message is a non-access layer extended service request with the circuit switched fallback response field set to 0.

12. The method for preventing triggering of a change between radio access technologies according to claim 9, wherein: Further comprising: rejecting the incoming call request by ignoring the incoming call request based on the response indicating that the user rejects the incoming call request, by the communication device.

13. The method for preventing triggering of inter-radio access technology change according to claim 12, characterized in that: The step of ignoring the incoming call request is performed by preventing the communication device from sending any response message of the incoming call request to the cellular network.

14. The method for preventing triggering of a change between radio access technologies according to claim 8, wherein: The incoming call request is a session initiation protocol invite message for an IP multimedia subsystem call, wherein the incoming call request is received when the communication device is in a fifth generation mobile management connection mode.

15. A method for preventing triggering of an inter-radio access technology change, comprising: An incoming circuit switched service request for triggering a circuit switched fallback process is received from a cellular network by a communication device, wherein: The communication device is in a connecting mode; Before triggering the circuit switched fallback process, asking the user, through the communication device, to accept or reject the incoming circuit switched service request; and By means of the communication device, it is determined whether to trigger the circuit switched fallback process based on the response of the user to the inquiry.

16. The method for preventing triggering of inter-radio access technology change according to claim 15, characterized in that: The step of determining whether to trigger the circuit switched fallback process based on the user's response to the inquiry includes: based on the response indicating that the user rejects the incoming circuit switched service request, rejecting or ignoring the incoming circuit switched service request, thereby avoiding triggering the circuit switched fallback process.

17. The method for preventing triggering of a change between radio access technologies according to claim 16, wherein: The method further comprises: sending, by the communication device, a message indicating rejection of the incoming circuit switching service request to the cellular network based on the response indicating that the user rejects the incoming circuit switching service request, so as to reject the incoming circuit switching service request.

18. The method for preventing triggering of a change between radio access technologies according to claim 17, characterized in that: This message is a non-access layer extended service request with the circuit switched fallback response field set to 0.

19. The method for preventing triggering of a change between radio access technologies according to claim 16, wherein: The method further includes: rejecting the incoming circuit switched service request by ignoring the incoming circuit switched service request based on the response indicating that the user rejects the incoming circuit switched service request by the communication device.

20. The method for preventing triggering of inter-radio access technology change according to claim 15, characterized in that: The incoming circuit-switched service request is a voice call request.

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