WO2025166780A1

WO2025166780A1 - Devices and methods for robust notification alert

Info

Publication number: WO2025166780A1
Application number: PCT/CN2024/077054
Authority: WO
Inventors: Gang Wang
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2024-02-08
Filing date: 2024-02-08
Publication date: 2025-08-14
Anticipated expiration: 2026-08-08

Abstract

Embodiments of the present disclosure provide a solution for robust notification alert. In a solution, a terminal device receives first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. In addition, or alternatively, the terminal device transmits, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

Description

DEVICES AND METHODS FOR ROBUST NOTIFICATION ALERT

FIELDS

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to devices and methods for robust notification alert via Narrow Band Internet of Things (NB-IoT) .

BACKGROUND

Satellite to User Equipment (UE) transmission typically has very limited power margin and usually requires line of sight for best performance. For Mobile Originated calls, users are aware of the channel quality and can achieve Line of sight (LOS) communication by consciously adjusting the spot of signal transmission/reception. For Mobile terminated calls, users are unaware of its channel condition and might miss important paging messages even within the LOS coverage area.

When a UE is inside a pocket or backpack, and/or inside a car, or being blocked by building and/or foliage, the additional path loss causes very low signal to noise ratio (SNR) at the receiver. Per 3GPP 5G New Radio (NR) Non-Terrestrial Network (NTN) standard, UE in Radio Resource Connection IDLE (RRC_IDLE) or Radio Resource Connection INACTIVE (RRC_INACTIVE) periodically wakes up to check for paging signal. When UE wakes up, it first tries to detect SSB for synchronization purpose and extracting MIB. Then, it tries to detect Physical Downlink Control Channel (PDCCH) and Physical Downlink Shared Channel (PDSCH) and check for paging messages.

SUMMARY

In a first aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to perform at least one of: receive first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or transmit, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In a second aspect, there is provided a first network device comprising: a processor configured to cause the first network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT.

In a third aspect, there is provided a second network device comprising: a processor configured to cause the second network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In a fourth aspect, there is provided a third network device comprising: a processor configured to cause the third network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In a fifth aspect, there is provided a fourth network device comprising: a processor configured to cause the fourth network device to: receive, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and transmit the IMS signaling support indicator to a fifth network device associated with a user plane.

In a sixth aspect, there is provided a fifth network device comprising: a processor configured to cause the fifth network device to: receive, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection.

In a seventh aspect, there is provided a sixth network device comprising: a processor configured to cause the sixth network device to: receive, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In an eighth aspect, there is provided a communication method performed by a terminal device. The method comprises: receiving first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or transmitting, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In a ninth aspect, there is provided a communication method performed by a first network device. The method comprises: transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT.

In a tenth aspect, there is provided a communication method performed by a second network device. The method comprises: transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In an eleventh aspect, there is provided a communication method performed by a third network device. The method comprises: transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In a twelfth aspect, there is provided a communication method performed by a fourth network device. The method comprises: receiving, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and transmitting the IMS signaling support indicator to a fifth network device associated with a user plane.

In a thirteenth aspect, there is provided a communication method performed by a fifth network device. The method comprises: receiving, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection.

In a fourteenth aspect, there is provided a communication method performed by a sixth network device. The method comprises: receiving, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB- IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In a fifteenth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the eighth, ninth, tenth, eleventh, twelfth, thirteenth, or fourteenth aspect.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some example embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

FIG. 1A illustrates an example communication environment in which embodiments of the present disclosure can be implemented;

FIG. 1B illustrates a further example communication environment in which embodiments of the present disclosure can be implemented;

FIG. 2 illustrates a signaling flow of an example process of robust notification alert via NB-IoT in accordance with some embodiments of the present disclosure;

FIG. 3A illustrates a signaling flow of an example process of system information acquisition in accordance with some embodiments of the present disclosure;

FIG. 3B illustrates a signaling flow of a further example process of system information acquisition in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates a signaling flow of an example process of capability exchange between a network device and a terminal device in accordance with some embodiments of the present disclosure;

FIG. 5A illustrates a signaling flow of an example process of IP Multimedia Subsystem (IMS) registration/re-registration via NB-IoT in accordance with some embodiments of the present disclosure;

FIG. 5B illustrates a signaling flow of a further process of IMS registration/re- registration via NB-IoT in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates a signaling flow of an example process of session establishment;

FIG. 7A illustrates a signaling flow of a further example process of session establishment in accordance with some embodiments of the present disclosure;

FIG. 7B illustrates a signaling flow of another example process of session establishment in accordance with some embodiments of the present disclosure;

FIG. 8A illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 8B illustrates a flowchart of a further method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 9 illustrates a flowchart of a method implemented at a first network device according to some example embodiments of the present disclosure;

FIG. 10 illustrates a flowchart of a method implemented at a second network device according to some example embodiments of the present disclosure;

FIG. 11 illustrates a flowchart of a method implemented at a third network device according to some example embodiments of the present disclosure;

FIG. 12 illustrates a flowchart of a method implemented at a fourth network device according to some example embodiments of the present disclosure;

FIG. 13 illustrates a flowchart of a method implemented at a fifth network device according to some example embodiments of the present disclosure;

FIG. 14 illustrates a flowchart of a method implemented at a sixth network device according to some example embodiments of the present disclosure;

FIG. 15 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, devices on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g., FR1 (e.g., 450 MHz to 6000 MHz) , FR2 (e.g., 24.25GHz to 52.6GHz) , frequency band larger than 100 GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator. In some embodiments, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In some embodiments, the first network device may be a first RAT device and the second network device may be a second RAT device. In some embodiments, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In some embodiments, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In some embodiments, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘one embodiment’ and ‘an embodiment’ are to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As used herein, the term “resource, ” “transmission resource, ” “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

Generally, there are two types of paging in 5G NR. The first type is about paging to trigger RRC setup, RRC request or RRC resumption. The second type is about System Information Modification and Earthquake and Tsunami Warning System (ETWS) /Commercial Mobile Alert System (CMAS) indications (Short Message) done by PDCCH Downlink Control Information (DCI) 1_0 with a Paging Radio Network Temporary Identifier (P_RNTI) and a short message.

When a notification/paging is addressed to a particular UE in a cell, the UE may experience very poor signal-to-noise ratio (SNR) conditions, which prevents the UE from receiving a normal paging message. Thus, it is desirable to maximize the probability for the UE to be informed of a mobile terminated call.

A candidate feature of a robust notification/paging has been discussed. This feature is triggered by a network device upon e.g. paging failure (i.e. when no paging response from the UE has been received by the network device) , or other criteria. This feature is applied only for a mobile terminated call. This feature informs a user of a mobile terminated call, so that the user may try and move to a location with better coverage. This feature is highly desirable for satellite networks to reach users experiencing low SNR or non-line of sight (NLOS) channel conditions.

It is important to ensure that paging messages are successfully received by the destined users. But, when the core network or the network device pages such UE in IDLE or INACTIVE mode, the UE may be in a very poor channel condition and may miss the 5G NR paging message due to very low SNR, even though it is still in the beam coverage of a Non-Terrestrial Network (NTN) system.

There are two scenarios of paging failure when a UE wakes up from sleep. In a first scenario, the UE can still successfully detect SSB. If the UE successfully decodes PDCCH but fails to decode PDSCH, the UE sends Hybrid Automatic Repeat Request (HARQ) Negative Acknowledgement (NACK) to a network device. The UE continues to stay awake waiting for the network device to retransmit the paging message accordingly in the PDSCH, until it eventually receives its paging message with some delay. In this case, no further discussion is needed.

In the first scenario, the UE may fail to decode PDCCH scheduling for paging even at the highest allowable PDCCH aggregation level or the most allowable redundancy in PDCCH. When no data is received, no HARQ NACK is sent, and UE goes back to sleep. The network device waits for the UE to wake up next time to send the paging message again. PDCCH scheduling failure can cause very long delay and waste downlink resource as the paging process repeats again and again.

In a second scenario, the UE can’ t successfully detect SSB which is originally designed for terrestrial communication.

Very poor link budget margin for downlink transmission is shown and a specific mechanism to enhance at least [6] dB for the PDCCH and PDSCH channel to improve the system performance has been proposed. This proposal may help address the problem described in the first scenario, but it does not help to solve the problem described in the second scenario, as measurement data have indicated that more than 18 dB additional power may be needed to overcome some of the most adverse shadowed condition.

There are many options to extend the downlink reception SNR for NTN communication in the second scenario, which include, for example but not limited to:

i) increasing the transmission power on satellite, doubling the transmit power to increase the received SNR by 3dB;

ii) increasing transmit (TX) antenna gain on satellite, doubling the antenna diameter to increase the received SNR by 6 dB;

iii) increasing receive (RX) antenna gain on UE;

iv) increasing repetition number of the physical layer waveform, with every double of the repetition number achieving as much as 3dB gain; and/or

v) combination of option i) -iv) .

As the satellite communication system is power limited, it will be difficult to obtain additional 18dB by increasing the onboard transmission power and TX antenna size due to satellite size, weight and cost constraints. Therefore, the above options i) and ii) are not feasible solution to enhance reception SNR. Similarly, the above option iii) is constrained by the size, weight, and cost of the UE, and therefore deemed infeasible. Increasing repetition number of the physical layer waveform only requires modem change. However, it will require at least 26 or 64 repetitions to obtain extra 18dB leading to much longer transmission and reception time. The UE will also use 64 times more power and time/frequency resource for the handshaking and therefore it is not that desirable either.

It has been observed that there are about 10%of users experience very poor downlink reception within NTN coverage, and the receiver SNR could be below the desired SNR by as much as 18dB. These users might miss or not receive in a timely manner downlink paging calls or paging short messages due to poor received SNR. These paging calls and paging messages, especially for public safety purpose, are important to all users.

Further, it has been observed that paging calls and paging short messages are user terminated calls and may experience lower SNR due to lower user cooperation. Even with enhanced PDCCH and PDSCH channels, the paging calls or paging messages may still not be delivered in a timely manner because the SSB can’ t be detected at UE.

It has also been observed that it is very difficult to extend the downlink channels to improve the reliability of downlink paging calls and messages.

To improve the reliability of paging message reception and solve the problem described in second scenario 2 for paging failure (for the 10%NTN users in the system) , user cooperation will be required. The improvement can only be achieved by informing the user that a paging message destinated for the user has been sent, and their cooperation is needed.

It has been proposed to allocate a dedicated Paging Alert Channel (PAC) in the current 5G NTN downlink spectrum. Very low code rate or low Modulation and Coding Scheme (MCS) plus large number of repetitions can be applied to the downlink paging alert channel to extend the received SNR by as much as 18 dB without affecting the rest of the physical downlink channels including PBCH for SSB, PDCCH and PDSCH to maintain the efficiency of the system. In addition, PAC can also presumably help maintaining synchronization with the network, which can speed up re-acquisition of the UE when it is moved to better reception location.

Paging Alert Channel will be used to notify the UE when normal paging calls and messages can’ t be delivered to the UE successfully in 5G NR paging channel. The Paging Alert Channel is downlink only and need not require acknowledgement from the UE under poor channel condition for two reasons. One is that the power consumption at receiver is much smaller than transmission. Downlink only Paging alert channel will utilize the repetition of physical waveform to extend the reception SNR at UE, and the power consumption increase at UE receiver is not as significant as requesting large number of repetitions at the UE transmitter. Another one is that only when a UE cannot detect NR SSB at all, the UE wakes up periodically to monitor the Paging Alert Channel and checks for paging alert messages. UEs are grouped to wake up at some designated time slot by certain rules, e.g., LSBs of UE’s ID. If there is a paging alert message for the UE, a user can be notified to move to a better reception location to respond to the normal paging message, resulting in simpler and more efficient system.

In summary, a paging alert channel will extend downlink operational coverage further with the help of user cooperation and can better serve the 10%of the users who experience poor channel condition. It will help to improve the paging channel reliability while maintaining UE power efficiency.

Additionally, more power are also allocated to the paging alert channel as an option, which will improve the reliability of reception or reduce repetition number to increase paging capacity, per operator’s choice.

NR_NTN enhancements (e.g., a dedicated channel for alert) is optimized to allow for reception of alert messages in very low SNR conditions (e.g., vehicles/boats/blockage) . It is intended to alert the UE to move to a better signal reception location for communication.

The intended robust alert/notification is expected to relate/interact directly with IMS, namely IMS call control (SIP Signalling) . This is because it is intended to alert the called party of an incoming MT call and the calling party: such information is available in the SIP INVITE message. NTN NB-IoT is specifically designed to allow data transfer in adverse radio conditions such as those targeted by the proposal. NB-IoT is a valid (transport) candidate that should be considered.

In some cases, when a UE is in very poor SNR conditions which prevent to receive a normal paging message, it is hardly to inform the UE of a mobile terminated call, which is undesirable. Thus, there is a need to improve the chance that UE can receive the call.

To solve this problem and other potential issues, embodiments of the present disclosure propose a solution for robust notification alert via NB-IoT. In the solution supporting NB-IoT based IMS signaling capabilities are exchanged between the UE and the network. Then, the UE performs IMS registration/re-registration via NB-IoT. The UE receives SIP invite via NB-IoT and then connects to NR for IMS incoming call. In this way, the ratio for performing a successful paging process is improved.

Principles and implementations of the present disclosure will be described in detail below with reference to the figures.

FIG. 1A illustrates an example communication environment 100A in which example embodiments of the present disclosure can be implemented. In the communication environment 100A, a plurality of communication devices, including a terminal device 105, a network device 110, an Access and Mobility Management Function (AMF) device 115, a Service Management Function (SMF) device 120, a User Plane Function (UPF) device 125, an IMS 130 (also referred to as an IMS device 130) , and a Next Generation (NG) -eNodeB (eNB) (NB-IoT) device 135 can communicate with each other. The IMS 130 may include for example, a Proxy-Call Session Control Function (P-CSCF) device. In some embodiments, the P-CSCF device is sometimes called as P-CSCF device 130.

The terminal device 105 may be a UE and the network device 110 may be a base station serving the UE. The network device 110 supports IMS media and may be located in a radio access network (RAN) . The network device 110 may be a network device associated with New Radio (NR) in the embodiments of FIG. 1A.

The AMF device 115 may be a server or a device or a node implementing a function responsible for managing registration, connection, accessibility, and mobility of terminal devices, e.g., UEs. The SMF device 120 may act as a bridge between the control and user planes, directing the UPF device 125 on how to handle user data based on the terminal device 105's service requirements and network policies. The UPF node 150 may execute the data plane actions specified by the SMF device 120, ensuring that user data packets are forwarded correctly and efficiently throughout the network. then IMS (P-CSCF device) 130 may be a server or a device or a node implementing a function responsible for multimedia traffic. The NG-eNB (NB-IoT) device 135 may be a base station related to NB-IoT.

It is to be understood that the number of devices and their connections shown in FIG. 1A are only for the purpose of illustration without suggesting any limitation. The communication environment 100A may include any suitable number of devices configured to implementing example embodiments of the present disclosure.

FIG. 1B illustrates a further example communication environment 100B in which embodiments of the present disclosure can be implemented. In the communication environment 100B, a plurality of communication devices, including the terminal device 105, the network device 110, the IMS (P-CSCF) device 130, a PDN Gateway (PGW) /Serving Gateway (SWG) device 145 and an eNB (which is an NB-IoT device) 150 can communicate with each other.

In the communication environment 100B, a plurality of communication devices communicate with each other. As shown, the MME device 140 may be a server or a device or a node implementing a function responsible for locating the UE in idle mode, calling process, including relay, and in simple terms, MME is responsible for the signaling processing part. The PGW/SWG device 145 acts as user anchor point between different access networks within 3GPP and between 3GPP access and Non 3GPP access networks. The eNB (NB-IoT) device 150 may be a network device related to NB-IoT.

In the following, for the purpose of illustration, some example embodiments are described with the terminal device 105 operating as a UE. The network device 110 may operate as a base station, for example, an eNB for Evolved Universal Terrestrial Radio Access (E-URTA) in the embodiments of FIG. 1B. In some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other device.

In some example embodiments, if the terminal device 105 is a terminal device and the network device 110 is a network device, a link from the network device 110 to the terminal device 105 is referred to as a downlink (DL) , while a link from the terminal device 105 to the network device 110 is referred to as an uplink (UL) . In DL, the network device 110 is a transmitting (TX) device (or a transmitter) and the terminal device 105 is a receiving (RX) device (or a receiver) . In UL, the terminal device 105 is a TX device (or a transmitter) and the network device 110 is a RX device (or a receiver) .

The communications in the communication environment 100A and/or 100 B may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New Radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

It is to be understood that the number of devices and their connections shown in FIGS. 1A and 1B are only for the purpose of illustration without suggesting any limitation. The communication environment 100A or 100B may include any suitable number of devices configured to implementing example embodiments of the present disclosure. Although not shown, it is to be understood that one or more additional devices may be located in the cell, and one or more additional cells may be deployed in the communication environment.

FIG. 2 illustrates a signaling flow 200 of an example process of robust notification alert via NB-IoT in accordance with some embodiments of the present disclosure. For purpose of discussion, the embodiments of FIG. 2 will be discussed with respect to FIG. 1A and FIG. 1B. In the embodiments of FIG. 2, the first network device 210 may be a network device, e.g., the NG-eNB 135 or the eNB 150. The second network device 220 may be the network device 110, e.g., a gNB. The third network device 230 may be the AMF device 115 or the MMF device 140. The fourth network device 240 may be the SMF device 120 or the PGW/SGW device 145. The fifth network device 250 may be the UPF device 125 or the PGW/SGW device 145. The sixth network device 260 may be the IMS or P-CSCF device 130.

As shown in FIG. 2, the first network device 210 transmits (262) first capability information (also known as ims-SignalingSupport) to the terminal device 105. The first capability information indicates an IMS signaling over NB-IoT support capability of the first network device associated with NB-IoT. The terminal device 105 receives (264) the first capability information. Alternatively, or in addition, the second network device 220 transmits (266) the first capability information to the terminal device 105 and the terminal device 105 receives (268) the first capability information.

In some embodiments, the first capability information may be included in system information. The first capability information may be included in, for example but not limited to, a MIB or one or more System Information Blocks (SIBs) . Specifically, if the network device supports IMS signaling over NB-IoT, the network device may send ims-SignalingSupport in SystemInformationBlockType1, other SIB (also known as SIBx) or MIB. If the terminal device 105 cannot camp on a NR cell, the terminal device 105 may search an available NB-IoT network. The terminal device 105 can receive NB-IoT SIB1 or SIBx, MIB and forward the ims-SignalingSupport in the received NB-IoT SIB1 or SIBx to upper layers, if present. An example for the other SIB may be SIB4. The SIB4 contains information relevant for inter-frequency cell re-selection (i.e. information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection) , which can also be used for NR idle/inactive measurements. The information element (IE) may include cell re-selection parameters common for a frequency as well as cell specific re-selection parameters.

In some embodiments, the system information may be received from the first network device 210 (e.g. E-UTRAN) , as shown in FIG. 3A. FIG. 3A illustrates a signaling flow 300A of an example process of system information acquisition in accordance with some embodiments of the present disclosure. For purpose of discussion, the embodiments of FIG. 3A will be discussed with respect to FIGS. 1A and 1B and FIG. 2. In the FIG. 3A, the first terminal device 210 may transmit the first capability information in MIB 305. In some further embodiments, the first terminal device 210 may transmit the first capability information in SIB1 310. Alternatively, the first terminal device 210 may transmit the first capability information in other SIBs 315 and 320.

In some further embodiments, the system information may be received from the second network device 220 (e.g., gNB) in a network supporting IMS media, as shown in FIG. 3B. FIG. 3B illustrates a signaling flow of a further example process of system information acquisition in accordance with some embodiments of the present disclosure. For purpose of discussion, the embodiments of FIG. 3B will be discussed with respect to FIGS. 1A-1B and FIG. 2. In the FIG. 3B, the second terminal device 220 may transmit the first capability information in MIB 325 or the second terminal device 220 may transmit the first capability information in SIB1 330. Alternatively, the terminal device 105 may transmit a system information request 335 to the second terminal device 220. In turn, the second terminal device 220 may transmit system information messages 345 and 350 to the terminal device 105 in other SIBs.

In some embodiments, the terminal device 105 may transmit second capability information to the third network device 230. The third network device 230 may be associated with access and mobility management and the second capability information may indicate an IMS signaling over NB-IoT support capability of the terminal device. The third network device 230 may receive the second capability information.

In some embodiments, the third network device 230 transmit (270) the first capability information to the terminal device 105 and the terminal device 105 receives (271) the first capability information. In this case, the terminal device 105 may transmit a registration request to the third network device 230. After receiving the registration request from the terminal device 105, the third network device 230 may transmit a registration accept message to the terminal device 105. The registration accept message may include the first capability information.

In some further embodiments, the second capability information may be included in the registration request and the second capability information may include an IMS signaling support indicator (also known as an IMS signaling over NB-IoT support indicator) . More details about such capability sharing will be discussed with reference to FIG 4 below.

For purpose of discussion, the embodiments of FIG. 4 will be discussed with respect to FIGS. 1A-1B and FIG. 2. Specifically, as shown in FIG. 4 that illustrates a signaling flow 400 of an example process of capability exchange between a network device and a terminal device in accordance with some embodiments of the present disclosure, when the terminal device 105 cannot detect the NR SSB, the terminal device 105 connects to an available first network device 210 (e.g. NG-eNB) . The terminal device 105 sends a registration request 405 to the third device 230 (e.g. an AMF device) via the first network device 210, which includes, for example but not limit to, a UE ID of the terminal device 105 and other parameters. If the terminal device 105 supports IMS signaling over NB-IoT, the terminal device 105 may set IMS signaling over NB-IoT support indicator in the registration request. The first network device 210 sends the registration request 410 to the third network device, which is included in N2 message.

Based on the received registration request, the third network device 230 authenticates and authorizes the UE terminal device 105, the third network device 230 sends a registration accept 420 to the terminal device 105 via the first network device 210. If third network device 230 supports IMS signaling over NB-IoT, the third network device 230 may set IMS signaling over NB-IoT support indicator in the registration accept. The first network device 210 sends a registration accept 425 to the terminal device 105 in RRC message.

In such a way, the terminal device 105 receives the registration accept 425 with the IMS signaling over NB-IoT support indicator, and the UE determines that the third network device 230 supports IMS signaling over NB-IoT. The capability is stored for the third network device 230 in the UE context.

The above embodiments are related to how to exchange IMS signaling over NB- IoT support capabilities between a UE and a network device. After the NB-IoT support capabilities are exchanged, the UE may perform IMS registration/re-registration via NB-IoT, which will be described in below.

In some embodiments, a registration procedure may be initiated by the terminal device 105. Specifically, the terminal device 105 transmits (272) an IMS signaling support indicator to the third network device 230. The IMS signaling support indicator may be also referred to as IMS signaling over NB-IoT support indicator, IMS signaling indicator or Data Network Name (DNN) /Single Network Slice Selection Assistance Information (S-NSSAI) which includes IMS signaling indicator. In some other embodiments, the terminal device 105 may transmit a message for establishing a data connection to the third network device 230, which includes the IMS signaling support indicator.

Still referring to FIG. 2, the third network device 230, after receiving (273) the IMS signaling support indicator, transmits (274) the IMS signaling support indicator to the fourth network device 240. The IMS signaling support indicator may be used for a data connection, such as a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity, or the like. In some embodiments, the IMS signaling support indicator may be also transmitted to the first network device 210, the second network device 220, a fourth network device 240 associated with session management, a fifth network device 250 associated with a user plane, and/or the like.

Then the first network device 210 may receive an IMS signaling support indicator from the third network device230 in a PDU session request or an initial context setup request.

The fourth network device 240 receives (276) the IMS signaling support indicator from the third network device 230, and transmits (278) the IMS signaling support indicator to the fifth network device 250 in turn. The fifth network device 250 receives (280) the IMS signaling support indicator from the fourth network device 240 accordingly. The data connection may include a PDU session or a PDN connectivity.

In some embodiments, in response to receiving a message indicating an accept of establishment of the data connection, the terminal device 105 may transmit (282) a first Radio Access Technology (RAT) Type indicating the NB-IoT in a registration request to a sixth network device 260 associated with the IMS, e.g., the IMS device 130. The IMS device 130 receives (284) the first RAT type and will be aware that the current RAT type of the terminal device 105 is related to the NB-IoT.

For purpose of discussion, the embodiments of FIG. 5A will be discussed with respect to FIGS. 1A-1B and FIG. 2. Specifically, as shown in FIG. 5A that illustrates a signaling flow 500 A of an example process of IMS registration/re-registration via NB-IoT in accordance with some embodiments of the present disclosure, the first network device 210 may act as a NG-eNB 135 associated with NB-IoT in FIG. 1, the third network device 230 may act as an AMF device 115 in FIG. 1, the fourth network device 240 may act as an SMF device 120 in FIG. 1, the fifth network device 250 may act as an UPF device 125 in FIG. 1 and the sixth network device 260 may act as an IMS device 130 in FIG. 1.

In this case, the terminal device 105 sends a PDU Session Establishment Request 505 to the first network device 210. Then, the first network device 210 sends PDU Session Establishment Request 510 to the third network device 230. If the terminal device 105 has received an IMS signaling over NB-IoT support indicator, the terminal device 105 may set the IMS signaling indicator or DNN/S-NSSAI which includes the IMS signaling indicator in the PDU Session Establishment Request 505.

The third network device 230 sends Nsmf_PDUSession_CreateSMContext Request 515 to the fourth network device 240, e.g., the SMF device 120, to request establishing a PDU session for the terminal device 105, which includes the received IMS signaling indicator or DNN/S-NSSAI.

The fourth network device 240 determines that the PDU session is used for IMS signaling and treats it with high priority. The fourth network device 240 then sends Nsmf_PDUSession_CreateSMContext Response 520 to third network device 230 to confirm receiving the PDU establishment.

The fourth network device 240 may send an N4 Session Establishment/Modification Request 525 to fifth network device 250 to request establishing a PDU session for the terminal device 105, which includes the IMS signaling indicator or DNN/S-NSSAI received in Step 2.

The fifth network device 250 considers the PDU session is used for IMS signaling and will treat it with high priority. The fifth network device 250 sends N4 Session Establishment/Modification Response 530 to the fourth network device 240 to confirm the PDU establishment.

The fourth network device 240 then sends Namf_Communication_N1N2MessageTransfer 535 to third network device 230 with PDU Session Establishment Accept, which includes the IP address allocated to the terminal device 105.

The N2 PDU Session Request 540 is send from third network device 230 to first network device 210, which includes the IMS signaling indicator to the first network device 210 and PDU Session Establishment Accept to the terminal device 105. The first network device 210 determines that the PDU session is used for IMS signaling and treats it with high priority.

The first network device 210 sends PDU Session Establishment Accept 545 to the terminal device 105 via RRC message.

The terminal device 105 initiate the IMS registration or re-registration (if the previous registration is still valid) request 550 to the six network device 260, which includes the RAT Type with NB-IoT.

The six network device 260 accepts the registration or re-registration, and sends Registration Accept 555 to the terminal device 105.

For purpose of discussion, the embodiments of FIG. 5B will be discussed with respect to FIGS. 1A-1B and FIG. 2. Further, as shown in FIG. 5B that illustrates a signaling flow 500B of a further process of IMS registration/re-registration via NB-IoT in accordance with some embodiments of the present disclosure, the first network device 210 may act as the eNB 150 associated with NB-IoT in FIG. 1, the third network device 230 may act as the MMF device 140 in FIG. 1, the seventh network device 501may act as the SGW/PGW device 145 in FIG. 1 and the sixth network device 260 may act as the IMS device 130 in FIG. 1.

The terminal device 105 sends a Attach Request 560 to the first network device 210 and then the first network device 210 sends a Attach Request 565 to the third network device 230. If the terminal device 105 has received an IMS signaling over NB-IoT support indicator, the terminal device 105 may set the IMS signaling indicator or DNN/S-NSSAI which includes IMS signaling indicator in the Attach Request 560.

The third network device 230 sends Create Session Request 570 to seventh network device 501 to request establishing a PDN connectivity for the terminal device 105, which includes the received IMS signaling indicator or DNN/S-NSSAI.

The seventh network device 501 determines that the PDN connectivity is used for IMS signaling and treats it with high priority. The seventh network device 501 sends Create Session Response 575 to third network device 230 to confirm receiving the request, which includes the IP address allocated to the terminal device 105.

The third network device 230 sends an Initial Context Setup Request or Downlink NAS Transport with Attach Accept 580 to first network device 210, which includes the IMS signaling indicator to the first network device 210 and Attach Accept to the terminal device 105. Attach Accept includes the IP Address allocated to the terminal device 105, which is received in the Create Session Response 575. The first network device 210 determines that the PDN connectivity is used for IMS signaling and treats it with high priority.

The first network device 210 sends Attach Accept 585 to the terminal device 105 via RRC message and the Attach is completed at 590. Then, the terminal device 105 initiate the IMS registration or re-registration (if the previous registration is still valid) request 595 to the sixth network device 260, which includes the RAT Type with NB-IoT. The sixth network device 260 accepts the registration or re-registration, and sends a Registration Accept 596 to the terminal device 105.

The above embodiments are related to how can a UE perform IMS registration/re-registration via NB-IoT. After registration, the UE may receive an SIP invite via NB-IoT and connect to NR for IMS incoming call, which will be described in below.

In some embodiments, the terminal device 105 may be under NB-IoT access. The terminal device 105 may further perform an Inter-RAT mobility from NB-IoT to a network supporting IMS media for an incoming call. A data connection in the network supporting IMS media may be maintained with the same IP address or a different IP address as a connection in the NB-IoT.

In some further embodiments, the terminal device 105 may transmit the IP address and/or a second RAT Type to the sixth network device 260. The second RAT Type may indicate a network supporting IMS media. The network supporting IMS media may include NR or Evolved Universal Terrestrial Radio Access (E-UTRA) . The sixth network device 260 may receive the first RAT Type indicating Narrowband Internet of Things (NB-IoT) , or the second RAT Type from the terminal device 105.

FIG. 6 illustrates a signaling flow of an example process of session establishment.

At step 1, UE#1 sends a Session initialization Protocol (SIP) INVITE request including an initial Session Description Protocol (SDP) , to the Proxy-Call Session Control Function (P-CSCF) #1 determined via the P-CSCF discovery mechanism. The initial SDP may represent one or more media for a multi-media session. It should be noted that a media offer without preconditions in general implies that the offering entity might expect to receive incoming media for any of the offered media as soon as the offer is received by the other endpoint. Therefore either an existing IP-CAN bearer is assumed to be available for use or the application is implemented such that incoming media is not expected until some later point in time.

At step 2, P-CSCF#1 examines the media parameters. If P-CSCF#1 finds media parameters not allowed to be used within an IMS session (based on P-CSCF local policies, or if available bandwidth authorization limitation information coming from the Policy and Charging Rules Function (PCRF) /Policy Control Function (PCF) , it rejects the session initiation attempt.

At step 3, P-CSCF#1 forwards the INVITE request to Service-Call Session Control Function (S-CSCF) #1 along the path determined upon UE#1’s most recent registration procedure.

At step 4, based on operator policy, S-CSCF#1 validates the user’s service profile and may invoke whatever service control logic is appropriate for this INVITE request. This may include routing the INVITE request to an Application Server, which processes the request further on.

At step 5, S-CSCF#1 forwards INVITE request to I-CSCF#2.

At step 6, I-CSCF#2 performs Location Query procedure with the Home Subscriber Server (HSS) to acquire the S-CSCF address of the destination user (S-CSCF#2) .

At step 7, Interrogating-Call Session Control Function (I-CSCF) #2 forwards the INVITE request to S-CSCF#2.

At step 8, Based on operator policy, S-CSCF#2 validates the user’s service profile and may invoke whatever service control logic is appropriate for this INVITE request. This may include routing the INVITE request to an Application Server, which processes the request further on.

At step 9, S-CSCF#2 forwards the INVITE request to P-CSCF#2 along the path determined upon UE#2’s most recent registration procedure.

At step 10, P-CSCF#2 examines the media parameters. If P-CSCF#2 finds media parameters not allowed to be used within an IMS session (based on P-CSCF local policies, or if available bandwidth authorization limitation information coming from the PCRF/PCF) , it rejects the session initiation attempt.

At step 11, P-CSCF#2 forwards the INVITE request to UE#2.

At steps 12-17, UE#2 may optionally generate a ringing message towards UE#1.

At step 18, depending on the bearer establishment mode selected for the IP-CAN session, resource reservation shall be initiated either by the UE or by the IP-CAN itself. UE#2 may reserve a dedicated IP-Connectivity Access Network (IP-CAN) bearer for media based on the media parameters received in the SDP offer. Otherwise, the IP-CAN#2 initiates the reservation of required resources after step 20 instead.

At step 19, UE#2 accepts the session with a 200 OK response. The 200 OK response is sent to P-CSCF#2.

At step 20, Based on operator policy, P-CSCF#2 may instruct PCRF/PCF to authorize the resources necessary for this session.

At steps 21-24, the 200 OK response traverses back to UE#1.

At step 25, Based on operator policy, P-CSCF#1 may instruct the PCRF/PCF to authorize the resources necessary for this session.

At step 26, P-CSCF#1 forwards the 200 OK response to UE#1.

At steps 27-31, UE#1 acknowledges the 200 OK with an ACK, which traverses back to UE#2.

At step 32, depending on the bearer establishment mode selected for the IP-CAN session, resource reservation shall be initiated either by the UE or by the IP-CAN itself. UE#1 may reserve a dedicated IP-CAN bearer for media based on the media parameters received in the SDP answer as shown in Figure 5.19h. Otherwise, the IP-CAN#1 initiates the reservation of required resources after step 25.

FIG. 7A illustrates a signaling flow 700A of a further example process of session establishment in accordance with some embodiments of the present disclosure. For purpose of discussion, the embodiments of FIG. 7A will be discussed with respect to FIGS. 1A-1B and FIG. 2. The terminal device 701 may be an example of the terminal deice 105. And the P-CSCF devices 702-703 may be examples of the IMS (P-CSCF) 130. Similar to those steps 1-11 in FIG. 6, the terminal device 105 transmits an INVITE 705 including SDP offer to P-CSCF device 702, and the P-CSCF device 702 transmits an INVITE 710 including SDP offer to the P-CSCF device 703. The terminal device 701 generate 715 a ringing.

Then, the terminal device 701 performs NR connection and IMS update and reserve IP CAN bear for media at 720. For the terminal device 701 under NB-IoT access, the terminal device 701 receives the INVITE from NB-IoT. The terminal device 701 shall indicate the incoming call, the calling party and prompting to a better NR-NTN coverage to the user. If the user decides to answer the call, the user should try to find a better NR-NTN coverage. The terminal device 701 continues searching for NR cell. When an available NR cell is searched, the UE shall connect to the NR RAN and 5GC network with Inter-RAT mobility from NB-IoT to NR. The 5GC maintains the PDU session in NR with the same/another IP address as the PDU session in NB-IoT. The terminal device 701 shall perform Re-Registration Request to the IMS to update the RAT Type/IP address to NR. IP Address is optional, when the IP address is changed from NB-IoT to NR access, the IP Address shall be included. After the successful NR connection and IMS update, the terminal device 701 indicates to the user that the incoming call is ready for answering.

Further, the user confirms answering the incoming call in the terminal device 701. The terminal device 701 accepts the session with a 200 OK response 725. The 200 OK response is sent to P-CSCF 703. Similar to those steps 20-32 in FIG. 6, the P-CSCF 703 authorize QoS resources at 730. The 200 OK response 735 traverses back to the P-CSCF 702. The P-CSCF 702 authorize QoS resources at 740. The 200 OK response 745 traverses back to the terminal device 105.

FIG. 7B illustrates a signaling flow 700B of another example process of session establishment in accordance with some embodiments of the present disclosure. For purpose of discussion, the embodiments of FIG. 7B will be discussed with respect to FIGS. 1A-1B and FIG. 2. The terminal device 701 may be an example of the terminal deice 105. And the P-CSCF devices 702-703 may be examples of the IMS (P-CSCF) 130. Similar to those steps 1-11 in FIG. 6, the terminal device 105 transmits an INVITE 750 including SDP offer to P-CSCF device 702, and the P-CSCF device 702 transmits an INVITE 755 including SDP offer to the P-CSCF device 703.

The terminal device 701 generate a ringing and performs NR connection and IMS update at 760. For the terminal device 701 under NB-IoT access, the terminal device 701 receives the INVITE from NB-IoT. terminal device 701 shall indicate the incoming call, the calling party and prompting to a better NR-NTN coverage to the user. If the user decides to answer the call, the user should try to find a better NR-NTN coverage. The UE continues searching for NR cell. When an available NR cell is searched, the UE shall connect to the NR RAN and 5GC network with Inter-RAT mobility from NB-IoT to NR. The 5GC maintains the PDU session in NR with the same IP address as the PDU session in NB-IoT. The terminal device 701 shall perform Re-Registration Request to the IMS to update the RAT Type/IP Address to NR. IP Address is optional, when the IP address is changed from NB-IoT to NR access, the IP Address shall be included. After the successful NR connection and IMS update, the terminal device 701 indicates to the user that the incoming call is ready for answering. The terminal device 701 reserves IP CAN bear for media at 765.

Further, the user confirms answering the incoming call in the terminal device 701. Similar to those steps 18-32 in FIG. 6, the terminal device 701 accepts the session with a 200 OK response 770. The 200 OK response is sent to P-CSCF 703. The P-CSCF 703 authorize QoS resources at 775. The 200 OK response 780 traverses back to the P-CSCF 702. The P-CSCF 702 authorize QoS resources at 785. The 200 OK response 790 traverses back to the terminal device 105.

In some embodiments, the first network device 210 may include a NG-eNB associated with NB-IoT and the third network device 230 may include an third network device 230 device. Alternatively, the first network device 210 may include a network device in E-UTRA and the third network device 230 may include an MME.

In some embodiments, the first network device 210 may include a network device associated with NB-IoT, and the second network device 220 may include a network device associated with NR or E-UTRA.

In some embodiments, the third network device 230 may include an AMF device, or an MME. The fourth network device 240 may include a SMF device, or a SGW and PGW. The fifth network device 250 may include a UPF device, or the SGW and PGW.

In some embodiments, the fourth network device 240 may include a SMF device or a SGW, and the fifth network device 250 may include a UPF device or an PGW.

In some embodiments, the sixth network device 260 may include an IMS or a P-CSCF device.

Embodiments of the present disclosure may introduce a new section for NB-IoT supporting IMS Signaling. For example, embodiments of the present disclosure may introduce NB-IoT supporting IMS Signaling with the capability exchange and IMS signaling PDU session indicator.

In addition, embodiments of the present disclosure may introduce adding NB-IoT supporting IMS Signalling capability in Registration Request, and/or adding IMS Signalling indicator in PDU session establishment procedure. In addition, embodiments of the present disclosure may introduce adding a new annex for NB-IoT supporting IMS signalling. In some cases, a new RAT Type NB-IoT is may be added in the registration request from UE to IMS.

In addition, in some embodiments of the present disclosure, SIBx (x indicates the index of the SIB) may include ims-SignalingSupport and the related UE behaviour. For instance, SIB 4 or NR Neighbor cell information of NB-IoT may include ims-SignalingSupport indicator.

FIG. 8A illustrates a flowchart of a communication method 800A implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 800A will be described from the perspective of a terminal device 105 in FIG. 1.

At block 810, the terminal device 105 receives first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. Additionally, in some embodiments, the terminal device 105 transmits, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

FIG. 8B illustrates a flowchart of a communication method 800B implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 800B will be described from the perspective of a terminal device 105 in FIG. 1.

At block 820, the terminal device 105 transmits, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device. Additionally, in some embodiments, the terminal device 105 receives first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In some example embodiments, the first capability information is comprised in system information received from the first network device or a second network device in a network supporting IMS media.

In some example embodiments, the first capability information is comprised in at least one of: a Master Information Block (MIB) , or one or more System Information Blocks (SIBs) .

In some example embodiments, the first capability information is received from a third network device associated with access and mobility management.

In some example embodiments, the terminal device 105 may further transmit a registration request to the third network device; and receive a registration accept message from the third network device, the registration accept message comprising the first capability information.

In some example embodiments, the registration request comprises second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In some example embodiments, the second capability information comprises an IMS signaling support indicator.

In some example embodiments, the terminal device 105 may further transmit an IMS signaling support indicator to a third network device associated with access and mobility management.

In some example embodiments, the terminal device 105 may further transmit, to the third network device, a message comprising the IMS signaling support indicator for establishing a data connection; and in response to receiving a message indicating an accept of establishment of the data connection, transmit, to a sixth network device associated with the IMS, a first Radio Access Technology (RAT) Type indicating the NB-IoT in a registration request.

In some example embodiments, the terminal device is under NB-IoT access, and the terminal device 105 may further perform an Inter-Radio Access Technology (RAT) mobility from NB-IoT to a network supporting IMS media for an incoming call, wherein a data connection in the network supporting IMS media is maintained with the same IP address or a different IP address as a connection in the NB-IoT.

In some example embodiments, the terminal device 105 may further transmit the IP address and/or a second RAT Type to a sixth network device associated with IP Multimedia Core Network Subsystem (IMS) , the second RAT Type indicating a network supporting IMS media.

In some example embodiments, the network supporting IMS media comprises New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

FIG. 9 illustrates a flowchart of a communication method 900 implemented at a first network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of a first network device 210 in FIG. 2.

At block 910, a first network device 210 transmits, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT.

In some example embodiments, the first capability information is via system information transmitted from the first network device.

In some example embodiments, the first network device 210 may further receive an IMS signaling support indicator from a third network device associated with access and mobility management, the IMS signaling support indicator being comprised in a PDU session request or an initial context setup request.

In some example embodiments, the first network device comprises a Next Generation (NG) -eNodeB (eNB) and the third network device comprises an Access and Mobility Management Function (AMF) device, or wherein the first network device comprises a network device in Evolved Universal Terrestrial Radio Access (E-UTRA) and the third network device comprises an Mobility Management Entity (MME) .

FIG. 10 illustrates a flowchart of a communication method 1000 implemented at a second network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of a second network device 220 in FIG. 2.

At block 1010, the second network device 220 transmits, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In some example embodiments, the first capability information is via system information transmitted from the second network device.

In some example embodiments, the first network device comprises a network device associated with NB-IoT, and the second network device comprises a network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

FIG. 11 illustrates a flowchart of a communication method 1100 implemented at a third network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1100 will be described from the perspective of a third network device 230 in FIG. 2.

At block 1110, the third network device 230 transmits, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In some example embodiments, the third communication device 230 may further receive, from the terminal device, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In some example embodiments, the third network device 230 may further receive a registration request from the terminal device; and transmit a registration accept message to the terminal device, the registration accept message comprising the first capability information.

In some example embodiments, the second capability information is comprised in the registration request.

In some example embodiments, the third network device 230 may further transmit an IMS signaling support indicator for a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity to at least one of: the first network device, a second network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) , a fourth network device associated with session management, or a fifth network device associated with a user plane.

In some example embodiments, the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) .

FIG. 12 illustrates a flowchart of a communication method 1200 implemented at a fourth network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of fourth network device 240 in FIG. 2.

At block 1210, the fourth network device 240 receives, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection.

At block 1220, the fourth network device 240 transmits the IMS signaling support indicator to a fifth network device associated with a user plane.

In some example embodiments, the data connection comprises a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity.

In some example embodiments, the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) , the fourth network device comprises a session management function (SMF) device, or a Serving GateWay (SGW) and an Packet Data Network (PDN) Gateway (PGW) , and the fifth network device comprises a user Plane Function (UPF) device, or the SGW and PGW.

FIG. 13 illustrates a flowchart of a communication method 1300 implemented at a fifth network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of a fifth network device 250 in FIG. 2.

At block 1310, the fifth network device 250 receives, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection.

In some example embodiments, the fourth network device comprises a session management function (SMF) device or a Serving GateWay (SGW) , and the fifth network device comprises a user Plane Function (UPF) device or an Packet Data Network (PDN) Gateway (PGW) .

FIG. 14 illustrates a flowchart of a communication method 1400 implemented at a sixth network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of a sixth network device 260 in FIG. 2.

At block 1410, the sixth network device 260 receives, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In some example embodiments, the sixth network device comprises an IP Multimedia Core Network Subsystem (IMS) or a Proxy-Call Session Control Function (P-CSCF) device.

FIG. 15 is a simplified block diagram of a device 1500 that is suitable for implementing embodiments of the present disclosure. The device 1500 can be considered as a further example implementation of any of the devices as shown in FIG. 1. Accordingly, the device 1500 can be implemented at or as at least a part of the terminal device 110 or the network device 120.

As shown, the device 1500 includes a processor 1510, a memory 1520 coupled to the processor 1510, a suitable transceiver 1540 coupled to the processor 1510, and a communication interface coupled to the transceiver 1540. The memory 1520 stores at least a part of a program 1530. The transceiver 1540 may be for bidirectional communications or a unidirectional communication based on requirements. The transceiver 1540 may include at least one of a transmitter 1542 and a receiver 1544. The transmitter 1542 and the receiver 1544 may be functional modules or physical entities. The transceiver 1540 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 1530 is assumed to include program instructions that, when executed by the associated processor 1510, enable the device 1500 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 1 to 15. The embodiments herein may be implemented by computer software executable by the processor 1510 of the device 1500, or by hardware, or by a combination of software and hardware. The processor 1510 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1510 and memory 1520 may form processing means 1550 adapted to implement various embodiments of the present disclosure.

The memory 1520 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1520 is shown in the device 1500, there may be several physically distinct memory modules in the device 1500. The processor 1510 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: receive first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or transmit, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a first network device comprising a circuitry is provided. The circuitry is configured to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the first network device as discussed above.

According to embodiments of the present disclosure, a second network device comprising a circuitry is provided. The circuitry is configured to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second network device as discussed above.

According to embodiments of the present disclosure, a third network device comprising a circuitry is provided. The circuitry is configured to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the third network device as discussed above.

According to embodiments of the present disclosure, a fourth network device comprising a circuitry is provided. The circuitry is configured to: receive, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and transmit the IMS signaling support indicator to a fifth network device associated with a user plane. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the fourth network device as discussed above.

According to embodiments of the present disclosure, a fifth network device comprising a circuitry is provided. The circuitry is configured to: receive, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the fifth network device as discussed above.

According to embodiments of the present disclosure, a sixth network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) . According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the sixth network device as discussed above.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

According to embodiments of the present disclosure, a terminal apparatus is provided. The terminal apparatus comprises means for receiving first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or means for transmitting, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device. In some embodiments, the first apparatus may comprise means for performing the respective operations of the method [AA-NUM] 00. In some example embodiments, the first apparatus may further comprise means for performing other operations in some example embodiments of the method [AA-NUM] 00. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a first network apparatus is provided. The first network apparatus comprises means for transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT. In some embodiments, the second apparatus may comprise means for performing the respective operations of the method 900. In some example embodiments, the second apparatus may further comprise means for performing other operations in some example embodiments of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a second network apparatus is provided. The second network apparatus comprises means for transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. In some embodiments, the third apparatus may comprise means for performing the respective operations of the method 1000. In some example embodiments, the third apparatus may further comprise means for performing other operations in some example embodiments of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a third network apparatus is provided. The third network apparatus comprises means for transmitting, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT. In some embodiments, the fourth apparatus may comprise means for performing the respective operations of the method 1100. In some example embodiments, the fourth apparatus may further comprise means for performing other operations in some example embodiments of the method 1100. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a fourth network apparatus is provided. The fourth network apparatus comprises means for receiving, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and means for transmitting the IMS signaling support indicator to a fifth network device associated with a user plane. In some embodiments, the fifth apparatus may comprise means for performing the respective operations of the method 1200. In some example embodiments, the fifth apparatus may further comprise means for performing other operations in some example embodiments of the method 1200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a fifth network apparatus is provided. The fifth network apparatus comprises means for receiving, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection. In some embodiments, the sixth apparatus may comprise means for performing the respective operations of the method 1300. In some example embodiments, the sixth apparatus may further comprise means for performing other operations in some example embodiments of the method 1300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a sixth network apparatus is provided. The sixth network apparatus comprises means for receiving, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) . In some embodiments, the seventh apparatus may comprise means for performing the respective operations of the method 1400. In some example embodiments, the seventh apparatus may further comprise means for performing other operations in some example embodiments of the method 1400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In summary, embodiments of the present disclosure provide the following aspects.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to perform at least one of: receive first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or transmit, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In some embodiments, the first capability information is comprised in system information received from the first network device or a second network device in a network supporting IMS media.

In some embodiments, the first capability information is comprised in at least one of: a Master Information Block (MIB) , or one or more System Information Blocks (SIBs) .

In some embodiments, the first capability information is received from a third network device associated with access and mobility management.

In some embodiments, the terminal device is further caused to: transmit a registration request to the third network device; and receive a registration accept message from the third network device, the registration accept message comprising the first capability information.

In some embodiments, the registration request comprises second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In some embodiments, the second capability information comprises an IMS signaling support indicator.

In some embodiments, the terminal device is further caused to: transmit an IMS signaling support indicator to a third network device associated with access and mobility management.

In some embodiments, the terminal device is further caused to: transmit, to the third network device, a message comprising the IMS signaling support indicator for establishing a data connection; and in response to receiving a message indicating an accept of establishment of the data connection, transmit, to a sixth network device associated with the IMS, a first Radio Access Technology (RAT) Type indicating the NB-IoT in a registration request.

In some embodiments, the terminal device is under NB-IoT access, and the terminal device is further caused to: perform an Inter-Radio Access Technology (RAT) mobility from NB-IoT to a network supporting IMS media for an incoming call, wherein a data connection in the network supporting IMS media is maintained with the same IP address or a different IP address as a connection in the NB-IoT.

In some embodiments, the terminal device is further caused to: transmit the IP address and/or a second RAT Type to a sixth network device associated with IP Multimedia Core Network Subsystem (IMS) , the second RAT Type indicating a network supporting IMS media.

In some embodiments, the network supporting IMS media comprises New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In an aspect, it is proposed a first network device comprising: a processor configured to cause the first network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT.

In some embodiments, the first capability information is via system information transmitted from the first network device.

In some embodiments, the first network device is further caused to: receive an IMS signaling support indicator from a third network device associated with access and mobility management, the IMS signaling support indicator being comprised in a PDU session request or an initial context setup request.

In some embodiments, the first network device comprises a Next Generation (NG) -eNodeB (eNB) and the third network device comprises an Access and Mobility Management Function (AMF) device, or wherein the first network device comprises a network device in Evolved Universal Terrestrial Radio Access (E-UTRA) and the third network device comprises an Mobility Management Entity (MME) .

In an aspect, it is proposed a second network device comprising: a processor configured to cause the second network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In some embodiments, the first capability information is via system information transmitted from the second network device.

In some embodiments, the first network device comprises a network device associated with NB-IoT, and the second network device comprises a network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In an aspect, it is proposed a third network device comprising: a processor configured to cause the third network device to: transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT.

In some embodiments, the third communication device is further caused to: receive, from the terminal device, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.

In some embodiments, the third network device is further caused to: receive a registration request from the terminal device; and transmit a registration accept message to the terminal device, the registration accept message comprising the first capability information.

In some embodiments, the second capability information is comprised in the registration request.

In some embodiments, the third network device is further caused to: transmit an IMS signaling support indicator for a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity to at least one of: the first network device, a second network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) , a fourth network device associated with session management, or a fifth network device associated with a user plane.

In some embodiments, the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) .

In an aspect, it is proposed a fourth network device comprising: a processor configured to cause the fourth network device to: receive, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and transmit the IMS signaling support indicator to a fifth network device associated with a user plane.

In some embodiments, the data connection comprises a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity.

In some embodiments, the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) , the fourth network device comprises a session management function (SMF) device, or a Serving GateWay (SGW) and an Packet Data Network (PDN) Gateway (PGW) , and the fifth network device comprises a user Plane Function (UPF) device, or the SGW and PGW.

In an aspect, it is proposed a fifth network device comprising: a processor configured to cause the fifth network device to: receive, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection.

In some embodiments, the fourth network device comprises a session management function (SMF) device or a Serving GateWay (SGW) , and the fifth network device comprises a user Plane Function (UPF) device or an Packet Data Network (PDN) Gateway (PGW) .

In an aspect, it is proposed a sixth network device comprising: a processor configured to cause the sixth network device to: receive, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-UTRA) .

In some embodiments, the sixth network device comprises an IP Multimedia Core Network Subsystem (IMS) or a Proxy-Call Session Control Function (P-CSCF) device.

In an aspect, a terminal device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the terminal device discussed above.

In an aspect, a first network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the first network device discussed above.

In an aspect, a second network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the second network device discussed above.

In an aspect, a third network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the third network device discussed above.

In an aspect, a fourth network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the fourth network device discussed above.

In an aspect, a fifth network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the fifth network device discussed above.

In an aspect, a sixth network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the sixth network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the first network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the second network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the third network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the fourth network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the fifth network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the sixth network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the first network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the second network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the third network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the fourth network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the fifth network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the sixth network device discussed above.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGS. 1 to 15. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A terminal device comprising:

a processor configured to cause the first communication device to perform at least one of:

receive first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; or

transmit, to a third network device associated with access and mobility management, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.
The device of claim 1, wherein the first capability information is comprised in system information received from the first network device or a second network device in a network supporting IMS media.
The device of claim 2, wherein the first capability information is comprised in at least one of:

a Master Information Block (MIB) , or

one or more System Information Blocks (SIBs) .
The device of claim 1, wherein the first capability information is received from a third network device associated with access and mobility management.
The device of claim 4, wherein the terminal device is further caused to:

transmit a registration request to the third network device; and

receive a registration accept message from the third network device, the registration accept message comprising the first capability information.
The device of claim 5, wherein the registration request comprises second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device, or

wherein the second capability information comprises an IMS signaling support indicator.
The device of claim 1, wherein the terminal device is further caused to:

transmit an IMS signaling support indicator to a third network device associated with access and mobility management. The device of claim 8, wherein the terminal device is further caused to:

transmit, to the third network device, a message comprising the IMS signaling support indicator for establishing a data connection; and

in response to receiving a message indicating an accept of establishment of the data connection, transmit, to a sixth network device associated with the IMS, a first Radio Access Technology (RAT) Type indicating the NB-IoT in a registration request.
The device of claim 1, wherein the terminal device is under NB-IoT access, and the terminal device is further caused to:

perform an Inter-Radio Access Technology (RAT) mobility from NB-IoT to a network supporting IMS media for an incoming call, wherein a data connection in the network supporting IMS media is maintained with the same IP address or a different IP address as a connection in the NB-IoT; and

transmit the IP address and/or a second RAT Type to a sixth network device associated with IP Multimedia Core Network Subsystem (IMS) , the second RAT Type indicating a network supporting IMS media.
The device of claim 2 or 8, wherein the network supporting IMS media comprises New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-URTA) .
A first network device comprising:

a processor configured to cause the first network device to:

transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of the first network device associated with NB-IoT.
The device of claim 10, wherein the first capability information is via system information transmitted from the first network device.
The device of claim 11, wherein the first capability information is comprised in at least one of:

a Master Information Block (MIB) , or

one or more System Information Blocks (SIBs) .
The device of claim 10, wherein the first network device is further caused to:

receive an IMS signaling support indicator from a third network device associated with access and mobility management, the IMS signaling support indicator being comprised in a PDU session request or an initial context setup request,

wherein the first network device comprises a Next Generation (NG) -eNodeB (eNB) and the third network device comprises an Access and Mobility Management Function (AMF) device, or

wherein the first network device comprises a network device in Evolved Universal Terrestrial Radio Access (E-URTA) and the third network device comprises an Mobility Management Entity (MME) .
A second network device comprising:

a processor configured to cause the second network device to:

transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT, wherein the first capability information is via system information transmitted from the second network device, wherein the first capability information is comprised in at least one of:

a Master Information Block (MIB) , or

one or more System Information Blocks (SIBs) ,

wherein the first network device comprises a network device associated with NB-IoT, and the second network device comprises a network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-URTA) .
A third network device comprising:

a processor configured to cause the third network device to:

transmit, to a terminal device, first capability information indicating an IP Multimedia Core Network Subsystem (IMS) signaling over Narrowband Internet of Things (NB-IoT) support capability of a first network device associated with NB-IoT; and

receive, from the terminal device, second capability information indicating an IMS signaling over NB-IoT support capability of the terminal device.
The device of claim 15, wherein the third network device is further caused to:

transmit an IMS signaling support indicator for a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity to at least one of: the first network device, a second network device associated with New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-URTA) , a fourth network device associated with session management, or a fifth network device associated with a user plane, wherein the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) .
A fourth network device comprising:

a processor configured to cause the fourth network device to:

receive, from a third network device associated with access and mobility management, an IMS signaling support indicator for a data connection; and

transmit the IMS signaling support indicator to a fifth network device associated with a user plane.
The device of claim 17, wherein the data connection comprises a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity, wherein the third network device comprises an Access and Mobility Management Function (AMF) device, or an Mobility Management Entity (MME) ,

the fourth network device comprises a session management function (SMF) device, or a Serving GateWay (SGW) and an Packet Data Network (PDN) Gateway (PGW) , and

the fifth network device comprises a user Plane Function (UPF) device, or the SGW and PGW.
A fifth network device comprising:

a processor configured to cause the fifth network device to:

receive, from a fourth network device associated with session management, an IMS signaling support indicator for a data connection. The device of claim 32, wherein the data connection comprises a Protocol Data Unit (PDU) session or a Packet Data Network (PDN) connectivity. wherein the fourth network device comprises a session management function (SMF) device or a Serving GateWay (SGW) ,

wherein the fifth network device comprises a user Plane Function (UPF) device or an Packet Data Network (PDN) Gateway (PGW) .
A sixth network device comprising:

a processor configured to cause the sixth network device to:

receive, from a terminal device, a first Radio Access Technology (RAT) Type indicating Narrowband Internet of Things (NB-IoT) , or a second RAT Type indicating New Radio (NR) or Evolved Universal Terrestrial Radio Access (E-URTA) ,

wherein the sixth network device comprises an IP Multimedia Core Network Subsystem (IMS) or a Proxy-Call Session Control Function (P-CSCF) device.