Patent ID: 12219650

DETAILED DESCRIPTION OF THE APPLICATION

The following description is made for the purpose of illustrating the general principles of the application and should not be taken in a limiting sense. It should be understood that the embodiments may be realized in software, hardware, firmware, or any combination thereof. The terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

FIG.1is a block diagram of a mobile communication environment according to an embodiment of the application.

As shown inFIG.1, the mobile communication environment100may include a User Equipment (UE)110and two service networks120and130.

The UE110may be a feature phone, a smartphone, a panel Personal Computer (PC), a laptop computer, or any wireless communication device supporting the RATs utilized by the service networks120and130.

The UE110may be selectively connected to one or both of the service networks120and130using one or more subscriber identities (or referred to as subscriber numbers). The subscriber identities may be provided by one or two subscriber identity cards (not shown) in compliance with the specifications of the RATs utilized by the service networks120and130. For example, the subscriber identity cards may include a Subscriber Identity Module (SIM) card if one of the service networks120and130is a GSM/GPRS/EDGE/IS-95 network, or may include a Universal SIM (USIM) card if one of the service networks120and130is a WCDMA/LTE/LTE-A/TD-LTE/NR network. Alternatively, the subscriber identities may be directly written into the UE110, without the need for any socket to insert any subscriber identity card, or the subscriber identities may be provided by one or more virtual subscriber identity cards (e.g., eSIM/eUSIM), and the present application is not limited thereto.

The service network120may include an access network121and a core network122, while the service network130may include an access network131and a core network132. The access networks121and131are responsible for processing radio signals, terminating radio protocols, and connecting the UE110with the core networks122and132, respectively. The core networks122and132are responsible for performing mobility management, network-side authentication, and interfaces with public/external networks (e.g., the Internet). The access networks121and131, and the core networks122and132may each comprise one or more network nodes for carrying out said functions.

In particular, the service networks120and130utilize different RATs.

For example, the service network120may be a 5G System (5GS) utilizing the NR technology, and the access network121and the core network122may be a Next Generation Radio Access Network (NG-RAN) and a Next Generation Core Network (NG-CN), respectively.

An NG-RAN may include one or more cellular stations, such as next generation NodeBs (gNBs), which support high frequency bands (e.g., above 24 GHz), and each gNB may further include one or more Transmission Reception Points (TRPs). Some gNB functions may be distributed across different TRPs, while others may be centralized, leaving the flexibility and scope of specific deployments to fulfill the requirements for specific cases.

A NG-CN generally consists of various network functions, including Access and Mobility Function (AMF), Session Management Function (SMF), Policy Control Function (PCF), Application Function (AF), Authentication Server Function (AUSF), User Plane Function (UPF), and User Data Management (UDM), wherein each network function may be implemented as a network element on a dedicated hardware, or as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

The AMF provides UE-based authentication, authorization, mobility management, etc. The SMF is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF for data transfer. If a UE has multiple sessions, different SMFs may be allocated to each session to manage them individually and possibly provide different functions per session. The AF provides information on the packet flow to PCF responsible for policy control in order to support Quality of Service (QoS). Based on the information, the PCF determines policies about mobility and session management to make the AMF and the SMF operate properly. The AUSF stores data for authentication of UEs, while the UDM stores subscription data of UEs.

For example, the service network130may be an Evolved Packet System (EPS) utilizing the LTE/LTE-A/TD-LTE technology, and the access network131and the core network132may be an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and an Evolved Packet Core (EPC), respectively.

The E-UTRAN may include at least an evolved NodeB (eNB) (e.g., a macro eNB, femto eNB, or pico eNB). The EPC may include a Home Subscriber Server (HSS), Mobility Management Entity (MME), Serving Gateway (S-GW), and Packet Data Network Gateway (PDN-GW or P-GW).

The HSS is a central database that contains user-related and subscription-related information. The functions of the HSS include functionalities such as mobility management, call and session establishment support, user authentication and access authorization.

The MME is responsible for idle mode UE paging and tagging procedures including retransmissions. It is involved in the bearer activation/deactivation process and is also responsible for choosing the S-GW for the UE110at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation. It is also responsible for user authentication (by interacting with the HSS) and generation/allocation of temporary identities to the UE110. It is also the termination point in the network for ciphering/integrity protection for Non Access Stratum (NAS) signaling and handles the security key management.

The S-GW is responsible for routing and forwarding user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies.

The P-GW provides connectivity from the UE110to external PDNs by being the point of exit and entry of traffic for the UE110. The PGW also provides the functions of policy enforcement, packet filtering for each user, charging support, lawful interception, and packet screening.

It should be understood that the mobile communication environment100described in the embodiment ofFIG.1is for illustrative purposes only and is not intended to limit the scope of the application. For example, the service network120may be a 6G network, while the service network130may be a 5GS; or the service network120may be an EPS, while the service network130may be a 5GS.

FIG.2is a block diagram illustrating a UE according to an embodiment of the application.

As shown inFIG.2, a UE may include a wireless transceiver10, a controller20, a storage device30, a display device40, and an Input/Output (I/O) device50.

The wireless transceiver10is configured to perform wireless transmission and reception to and from the service network120and/or the service network130.

Specifically, the wireless transceiver10may include a baseband processing device11, a Radio Frequency (RF) device12, and antenna13, wherein the antenna13may include an antenna array for beamforming.

The baseband processing device11is configured to perform baseband signal processing and control the communications between subscriber identity card(s) (not shown) and the RF device12. The baseband processing device11may contain multiple hardware components to perform the baseband signal processing, including Analog-to-Digital Conversion (ADC)/Digital-to-Analog Conversion (DAC), gain adjusting, modulation/demodulation, encoding/decoding, and so on.

The RF device12may receive RF wireless signals via the antenna13, convert the received RF wireless signals to baseband signals, which are processed by the baseband processing device11, or receive baseband signals from the baseband processing device11and convert the received baseband signals to RF wireless signals, which are later transmitted via the antenna13. The RF device12may also contain multiple hardware devices to perform radio frequency conversion. For example, the RF device12may comprise a mixer to multiply the baseband signals with a carrier oscillated in the radio frequency of the supported RAT(s), wherein the radio frequency may be any radio frequency (e.g., 30 GHz-300 GHz for mmWave) utilized in the NR technology, or may be 900 MHz, 2100 MHz, or 2.6 GHz utilized in the LTE/LTE-A/TD-LTE technology, or another radio frequency, depending on the RAT in use.

The controller20may be a general-purpose processor, a Micro Control 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), or the like, which includes various circuits for providing the functions of data processing and computing, controlling the wireless transceiver10for wireless communication with the service network120and/or the service network130, storing and retrieving data (e.g., program code) to and from the storage device30, sending a series of frame data (e.g. representing text messages, graphics, images, etc.) to the display device40, and receiving user inputs or outputting signals via the I/O device50.

In particular, the controller20coordinates the aforementioned operations of the wireless transceiver10, the storage device30, the display device40, and the I/O device50for performing the method of the present application.

In another embodiment, the controller20may be incorporated into the baseband processing device11, to serve as a baseband processor.

As will be appreciated by persons skilled in the art, the circuits of the controller20will typically include transistors that are configured in such a way as to control the operation of the circuits in accordance with the functions and operations described herein. As will be further appreciated, the specific structure or interconnections of the transistors will typically be determined by a compiler, such as a Register Transfer Language (RTL) compiler. RTL compilers may be operated by a processor upon scripts that closely resemble assembly language code, to compile the script into a form that is used for the layout or fabrication of the ultimate circuitry. Indeed, RTL is well known for its role and use in the facilitation of the design process of electronic and digital systems.

The storage device30may be a non-transitory machine-readable storage medium, including a memory, such as a FLASH memory or a Non-Volatile Random Access Memory (NVRAM), or a magnetic storage device, such as a hard disk or a magnetic tape, or an optical disc, or any combination thereof for storing data, instructions, and/or program code of applications, communication protocols, and/or the method of the present application.

The display device40may be a Liquid-Crystal Display (LCD), a Light-Emitting Diode (LED) display, an Organic LED (OLED) display, or an Electronic Paper Display (EPD), etc., for providing a display function. Alternatively, the display device40may further include one or more touch sensors disposed thereon or thereunder for sensing touches, contacts, or approximations of objects, such as fingers or styluses.

The I/O device50may include one or more buttons, a keyboard, a mouse, a touch pad, a video camera, a microphone, and/or a speaker, etc., to serve as the Man-Machine Interface (MMI) for interaction with users.

It should be understood that the components described in the embodiment ofFIG.2are for illustrative purposes only and are not intended to limit the scope of the application. For example, a UE may include more components, such as a power supply, a Global Positioning System (GPS) device, and/or another wireless transceiver. The power supply may be a mobile/replaceable battery providing power to all the other components of the UE. The GPS device may provide the location information of the UE for use by some location-based services or applications. In case the UE supports dual registration with 5GS and EPS, an additional wireless transceiver may be used for wireless transmission and reception to and from one service network, while the wireless transceiver10may be used for wireless transmission and reception to and from another service network. Alternatively, a UE may include fewer components. For example, a UE may not include the display device40and/or the I/O device50.

FIG.3is a flow chart illustrating the method for multi-RAT coordination according to an embodiment of the application.

In this embodiment, the method for multi-RAT coordination may be applied to and executed by a UE (e.g., the UE110) wirelessly and communicatively connected to one or both of a first service network (e.g., the service network120) utilizing a first RAT and a second service network (e.g., the service network130) utilizing a second RAT.

To begin with, the UE sends an indicator of a connection release request to the first service network in response to terminating a first communication service with the first service network or in response to leaving the first service network for the second service network (step S310).

In one embodiment, the indicator of the connection release request may be sent in a Non-Access Stratum (NAS) message.

Specifically, the NAS message may be an Evolved Packet System (EPS) Mobility Management (EMM) message or an EPS Session Management (ESM) message, if the first service network is an EPS. For example, the EMM message may be a Tracking Area Update message or an EMM Status message, and the ESM message may be a Tracking Area Update message or an EMM Status message.

Alternatively, the NAS message may be a 5G Mobility Management (5GMM) message, if the first service network is a 5GS. For example, the 5GMM message may be a Registration Request message, an UL NAS transport message, or a 5GMM Status message.

In another embodiment, the indicator of the connection release request may be sent in a Radio Resource Control (RRC) message. For example, the RRC message may be a UE Assistance Information message.

It should be noted that the indicator of the connection release request is a new Information Element (IE) introduced in the NAS message or the RRC message.

Subsequent to step S310, the UE releases an RRC connection with the first service network after sending the indicator of the connection release request (step S320).

In one embodiment, both the UE and the first service network may locally release the RRC connection in response to the indicator of the connection release request, without waiting or sending a response to the indicator. That is, the UE may locally release the RRC connection upon sending the indicator of the connection release request, while the first service network may locally release the RRC connection upon receiving the indicator of the connection release request.

In another embodiment, the UE may have to wait for an RRC Connection Release message from the first service network after sending the indicator of the connection release request, and release the RRC connection with the first service network only when receiving an RRC Connection Release message from the first service network. Moreover, the UE may further start a timer in response to sending the indicator of the connection release request, and release the RRC connection with the first service network only when the timer expires but no RRC Connection Release message is received from the first service network.

FIGS.4A-4Bshow a message sequence chart illustrating multi-RAT coordination according to an embodiment of the application.

In this embodiment, the UE may be a 5GS/EPS capable UE (i.e., a 4G/5G multi-mode UE).

In step S401, the UE connects to the 4G network for making a Voice over LTE (VoLTE) call (e.g., a Mobile-Originated (MO) call or a Mobile-Terminated (MT) call).

In step S402, the VoLTE call ends, and the UE determines to go to 5GS from EPS.

Next, two alternatives are provided to enable the UE to return to 5GS after finishing the voice call service in the 4G network.

[Alternative 1]

In step S403A, the UE sends a NAS/RRC message including an indicator of a connection release request to the 4G network. Please note that the indicator may also be referred to as an indicator of the voice call being finished.

In step S404A, the UE locally releases the RRC connection with the 4G network in response to sending the indicator.

In step S405A, the 4G network locally releases the RRC connection with the UE in response to receiving the indicator.

That is, in alternative 1, both the UE and the 4G network may release the RRC connection as soon as the NAS/RRC message including the indicator is sent or received, without waiting to receive or send a response to the NAS/RRC message including the indicator.

[Alternative 2]

In step S403B, the UE sends a NAS/RRC message including an indicator of a connection release request to the 4G network.

In step S404B, the UE starts a timer upon sending the NAS/RRC message including the indicator.

In step S405B, the 4G network sends an RRC Connection Release message to the UE in response to receiving the NAS/RRC message including the indicator.

In step S406B, the 4G network locally releases the RRC connection upon sending the RRC Connection Release message.

In step S407B, the UE stops the timer in response to receiving an RRC Connection Release message from the 4G network before the timer expires.

In step S408B, the UE locally releases the RRC connection with the 4G network in response to receiving the RRC Connection Release message.

In step S409B, the timer expires and no RRC Connection Release message is received from the 4G network.

In step S410B, the UE locally releases the RRC connection with the 4G network in response to the timer expiring and not receiving an RRC Connection Release message from the 4G network.

In step S411, the UE reselects from the 4G network to the 5G network after the RRC connection with the 4G network is released.

That is, in alternative 2, the UE needs to wait for a response to the NAS/RRC message from the 4G network, before releasing the RRC connection with the 4G network. Optionally, a guard timer may be used to allow the UE to release the RRC connection in case of no response being received from the 4G network in a period of time.

It should be understood that the message sequence chart described in the embodiment ofFIGS.4A-4Bis for illustrative purposes only and is not intended to limit the scope of the application. For example, the NAS message including the indicator may be used to trigger a network-initiated inter-system change (including handover or redirection) from an EPS to a 5GS, instead of the RRC connection release procedure. Alternatively, the RRC message including the indicator may be used to trigger an inter-RAT handover to NR, instead of the RRC connection release procedure.

In view of the forgoing embodiment ofFIGS.4A-4B, it will be appreciated that the multi-RAT coordination proposed in the present application realizes a more robust and efficient mobile communication service with the supported RATs, by allowing a 5GS/EPS capable UE to return to a 5GS after finishing the voice call in an EPS. Advantageously, the 5GS/EPS capable UE may be able to obtain faster mobile broadband Internet access from the 5GS.

FIGS.5A-5Bshow a message sequence chart illustrating multi-RAT coordination according to another embodiment of the application.

In this embodiment, the UE may be a multi-SIM UE with limited Tx/Rx capability (e.g., the UE only has a single RF device).

In step S501, the UE connects to the 5G network (e.g., belonging to PLMN1) for a data service using SIM1.

In step S502, the UE determines to leave the 5G network due to initiating a specific activity (e.g., making a VoLTE call) with the 4G network (e.g., belonging to PLMN2) using SIM2.

Next, two alternatives are provided to enable the UE to synchronize the SIM1 state with the 5G network before performing the specific activity with the 4G network using SIM2.

[Alternative 1]

In step S503A, the UE sends a NAS/RRC message including an indicator of a connection release request to the 5G network. Please note that the indicator may also be referred to as an indicator of the UE switching to another RAT network.

In step S504A, the UE locally releases the RRC connection with the 5G network for SIM1 in response to sending the indicator.

In step S505A, the 5G network locally releases the RRC connection with the UE for SIM1 in response to receiving the indicator.

That is, in alternative 1, both the UE and the 5G network may release the RRC connection for SIM1 as soon as the NAS/RRC message including the indicator is sent or received, without waiting to receive or send a response to the NAS/RRC message including the indicator.

[Alternative 2]

In step S503B, the UE sends a NAS/RRC message including an indicator of a connection release request to the 5G network for SIM1.

In step S504B, the UE starts a timer upon sending the NAS/RRC message including the indicator.

In step S505B, the 5G network sends an RRC Connection Release message to the UE in response to receiving the NAS/RRC message including the indicator.

In step S506B, the 5G network locally releases the RRC connection with the UE for SIM1 upon sending the RRC Connection Release message.

In step S507B, the UE stops the timer in response to receiving an RRC Connection Release message from the 5G network before the timer expires.

In step S508B, the UE locally releases the RRC connection with the 5G network for SIM1 in response to receiving the RRC Connection Release message.

In step S509B, the timer expires and no RRC Connection Release message is received from the 5G network.

In step S510B, the UE locally releases the RRC connection with the 5G network for SIM1 in response to the timer expiring and not receiving an RRC Connection Release message from the 5G network.

In step S511, the UE performs the specific activity (e.g., making a VoLTE call) with the 4G network using SIM2.

That is, in alternative 2, the UE needs to wait for a response to the NAS/RRC message from the 5G network, before releasing the RRC connection with the 5G network. Optionally, a guard timer may be used to allow the UE to release the RRC connection in case of no response being received from the 5G network in a period of time.

It should be understood that the message sequence chart described in the embodiment ofFIGS.5A-5Bis for illustrative purposes only and is not intended to limit the scope of the application. For example, SIM2 may be used to initiate the specific activity with another 5G network, instead of the 4G network; or the multi-SIM UE may send the NAS/RRC message including the indicator to a 4G network, if the multi-SIM UE determines to leave the 4G network to perform a specific activity with a 5G network using one SIM when a data service with the 4G network is ongoing using another SIM. In addition, the NAS message including the indicator may be used to trigger a network-initiated inter-system change (including handover or redirection) from an EPS to a 5GS or from a 5GS to an EPS, instead of the RRC connection release procedure. Alternatively, the RRC message including the indicator may be used to trigger an inter-RAT handover to NR or LTE, instead of the RRC connection release procedure.

In view of the forgoing embodiment ofFIGS.5A-5B, it will be appreciated that the multi-RAT coordination proposed in the present application realizes a more robust and efficient mobile communication service with the supported RATs, by allowing a multi-SIM UE to synchronize the connection state with the current RAT network before leaving for another RAT network using another SIM. Advantageously, the radio resource management at the network side may be improved. Moreover, the application layer of the multi-SIM UE may be promptly informed of the state transition of SIM1 from connected mode to idle mode, and countermeasures (e.g., continuing the data service on another SIM) may be taken as soon as possible to improve the user experience regarding service continuity.

While the application has been described by way of example and in terms of preferred embodiment, it should be understood that the application is not limited thereto. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this application. Therefore, the scope of the present application shall be defined and protected by the following claims and their equivalents.

Use of ordinal terms such as “first”, “second”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements.