WO2022092897A1

WO2022092897A1 - Methods and systems for handling a data session in a 5g user equipment

Info

Publication number: WO2022092897A1
Application number: PCT/KR2021/015444
Authority: WO
Inventors: Rishav Agarwal; Shanthossh Nagarajan; Shouvik Guha; Sumit Verma; Brijendra Kumar ASTHANA
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2020-10-31
Filing date: 2021-10-29
Publication date: 2022-05-05

Abstract

In an embodiment, a method for handling a data session associated with a 5G user equipment (UE). The method includes detecting a requirement to handover an on-going non-voice over new radio (non-VoNR) call and a data session from a non-5G cell to a 5G cell. The method includes sending a handover request for the on-going non-VoNR call to the 5G cell. The method includes detecting whether the non-VoNR call is handled by the 5G cell as a voice over NR (VoNR) call or not. The method includes performing one of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell as a VoNR call and delaying of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an EPSFB procedure.

Description

METHODS AND SYSTEMS FOR HANDLING A DATA SESSION IN A 5G USER EQUIPMENT

The present disclosure, in general, relates to network procedures performed by user equipment (UE), and, in particular, relates to network procedures performed by a UE for handling a data session.

Traditionally, the current 5^th generation (5G) stand alone (SA) deployments voice over new radio (VONR) support is not yet available. This implies that when a UE on wireless-fidelity (Wi-Fi) call moves to SA coverage evolved packet system (EPS) fall-back (EPSFB) has to be triggered to shift the on-going voice services to long term evolution (LTE). This happens after the request for the establishment voice call is redirected to legacy radio access technology (RAT) by network due to network's unavailability for VoNR support. In this scenario, if a data session is ongoing on Wi-Fi along with the call services, the protocol data unit (PDU) sessions are also established for these services over SA network. The upper layers can trigger a new PDU session request while EPSFB process is in progress. It is futile to establish data sessions on NR with voice service ongoing, since the device has to ultimately mobilize to LTE to keep supporting the call. The current provisions suffer from 2 major disadvantages:

Since the UE will have to ultimately undergo mobility to voice over LTE (VOLTE)/legacy to support the call, it is a wastage of resources, and power to establish independent PDU sessions for the services other than call.

After voice call trigger by UE and corresponding EPSFB trigger by network (NW), UE has to initiate a release request for other ongoing PDU sessions before the detach resulting in additional signaling overhead and latency.

Voice services are of prime importance to any mobile phone. There are multiple methods to provide voice services - via circuit switched calls (legacy 2^nd generation (2G)/ 3^rd generation (3G)/ code division multiple access (CDMA)) / via packet switched calls (LTE) / via voice over internet protocol (VoIP) etc.

During launch of LTE which was a packet service only based system (as opposed to legacy 2G/3G systems, which had circuit switched systems for voice services and packet switched systems for data services), since voice services were not supported directly on LTE initially due to multiple reasons, there was a method of circuit switched fallback, wherein the call triggered on LTE was redirected to a collocated legacy cell (2G or 3G) which was achieved by means of a procedure called circuit switched fallback (CSFB) - circuit switched fallback.

The same happened when NR 5G standalone, wherein the network did not initially support voice over NR (VoNR) services, wherein the standalone 5G cell could not provide the necessary quality of service flow (QoS) for call services due to multiple reasons including but not limited to hardware capability, software capability, back-end node connectivity, etc.

With the deployment of 5G standalone systems, and with availability of limited spectrum supporting all technologies, it was even more time-critical for network operators to introduce a Voice over New Radio (VoNR) service early and migrate the customers to a complete 5G system as soon as possible.

The approach of network operators has been taking a phased direction to introduce a complete 5G system into the existing networks, which started with the introduction of non-standalone (NSA) architecture, where LTE node (eNodeB) serves as the master node / controlling anchor for the 5G node (gNodeB). With NSA architecture, IP multimedia subsystem (IMS) services, including voice calling, will utilize the LTE network without impacting the control plane signalling, following the same approach as done in legacy LTE system. Hence this lead to no change in quality of service to the end user or quality of experience of voice services as this is the same as voice over LTE (VoLTE). When 5G standalone (SA) gets to an advanced phase, Non-standalone and Standalone architectures will coexist in operator's networks across the world. In areas where only 5G SA is available, it is important that all existing voice services which are the most important service of any cellular phone / mobile, as it includes at least emergency call services over NR not to face any issue.

Coming to early 5G SA deployment from operators, EPSFB will be the temporary solution for call services for devices camped on 5G, requiring a collocated LTE coverage under the 5G SA cell. EPSFB is not the long-term solution, but it is just like CSFB introduced in the early days of LTE. Considering now VoLTE development worldwide as an enabler for voice services in 5G SA, VoNR deployment in the ecosystem early will be essential to the success of migration towards complete 5G.

VoLTE and VoNR use the same backend - IMS. Though the IMS core network architecture remains the same, technical advancements of 5G new radio, 5GC and 5G devices are expected to provide superior user experience in VoNR as opposed to VoLTE when the VoNR feature is fully functional.

Fig. 1 illustrates an overview of a mechanism 100 depicting a current EPS-FB mechanism, in accordance with an existing technique.

Fig. 2 illustrates an environment 200 depicting a UE in LTE, voice over Wi-Fi (Vo-WiFi) + data ongoing, mobility towards 5G SA, in accordance with an existing technique. With Vo-WiFi and data ongoing, and UE moving from LTE to NR SA coverage, B2 measurement will cause inter RAT hand-over to NR, and UE will initiate PDU sessions for both - voice and data. Data PDU sessions are overhead since UE will have to move to LTE to continue voice services.

Thus, there is a need for a solution that overcomes the above deficiencies.

This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

The present subject matter refers a method for handling a data session associated with a 5G user equipment (UE). The method includes detecting a requirement to handover an on-going non-voice over new radio (non-VoNR) call and a data session from a non-5G cell to a 5G cell. The method includes sending a handover request for the on-going non-VoNR call to the 5G cell. The method includes detecting whether the non-VoNR call is handled by the 5G cell as a VoNR call or not. The method includes performing one of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell as a VoNR call and delaying of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an evolved packet core fall back (EPSFB) procedure.

The present subject matter refers a method for handling a data session in a 5G user equipment (UE). The method includes detecting a need to handover an ongoing non-VoNR call and a data session from a first cell to a 5G cell. The method includes sending a request to establish a call bearer with the 5G cell for a non VoNR call. The method includes ascertaining if the call bearer with the 5G cell for the non-VoNR call is successfully established. The method includes performing one of sending a request to establish a protocol data unit　(PDU) session for the data session on the 5G cell if the call bearer with the 5G cell for the non-VoNR call is successfully established and sending a request to establish the PDU session for the data session on a second cell if the call bearer with the 5G cell for the VoNR call is not successfully established.

The present subject matter refers a system for handling a data session associated with a 5G user equipment (UE). The system includes a processor configured to detect a requirement to handover an on-going non-voice over new radio (non-VoNR) call and a data session from a non-5G cell to a 5G cell. The processor is further configured to send a handover request for the on-going non-VoNR call to the 5G cell. The processor is configured to detect whether the non-VoNR call is handled by the 5G cell as a voice over NR (VoNR) call or not. The processor is also configured to perform one of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell as a VoNR call and delaying of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an EPSFB procedure.

The present subject matter refers a system for handling a data session in a 5G user equipment (UE). The system includes a processor configured to detect a need to handover an ongoing non-VoNR call and a data session from a first cell to a 5G cell. The processor is configured to send a request to establish a call bearer with the 5G cell for a non VoNR call. The processor is configured to ascertain if the call bearer with the 5G cell for the non-VoNR call is successfully established. The processor is configured to perform one of sending a request to establish a PDU session for the data session on the 5G cell if the call bearer with the 5G cell for the non-VoNR call is successfully established and sending a request to establish the PDU session for the data session on a second cell if the call bearer with the 5G cell for the VoNR call is not successfully established.

To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

Before undertaking the detailed description below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation; the term "or," is inclusive, meaning and/or; the phrases "associated with" and "associated therewith," as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term "controller" means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A "non-transitory" computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Fig. 2 illustrates an environment 200 depicting a UE in LTE, Vo-WiFi + data ongoing, Mobility towards 5G SA, in accordance with an existing technique.

Fig. 3 illustrates a schematic block diagram depicting a method, for handling a data session associated with a 5G UE, in accordance with an embodiment of the present subject matter;

Fig. 4 illustrates an operational flow diagram depicting a process for handling data session associated with a 5G UE, in accordance with an embodiment of the present subject matter;

Fig. 5 illustrates a schematic block diagram depicting to handle a data session in a 5G User Equipment, in accordance with an embodiment of the present subject matter;

Fig. 6 illustrates an operational flow diagram depicting a process for a UE continuing to establish remaining sessions, in accordance with an embodiment of the present subject matter;

Fig. 7 illustrates an operational flow diagram depicting another process for a UE continuing to establish remaining sessions, in accordance with an embodiment of the present subject matter;

Fig. 8 illustrates an operational flow diagram depicting a process for a UE to initiate request for IMS, in accordance with an embodiment of the present subject matter;

Fig. 9 illustrates an operational flow diagram depicting a process for a UE to initiate request for IMS, in accordance with an embodiment of the present subject matter;

Fig. 10 illustrates an operational flow diagram for depicting a process for a UE to attempt to establish PDU session for IMS instead of establishing active PDU sessions, in accordance with an embodiment of the present subject matter;

Fig. 11 illustrates an operational flow diagram for depicting another process for a UE to attempt to establish PDU session for IMS instead of establishing active PDU sessions, in accordance with an embodiment of the present subject matter; and

Fig. 12 is schematic block diagram of a diagram illustrating a configuration of a terminal in a wireless communication system according to an embodiment of the present subject matter.

Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

For promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises. a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

Fig. 3 illustrates a schematic block diagram 300 depicting a method, for handling a data session associated with a 5G UE, in accordance with an embodiment of the present subject matter. In an embodiment, handling of the data session may be based on continuing the data session on one of a 5G cell and a 4G cell. In an embodiment, an on-going non-VoNR call may also be handled by one of the 5G cell and the 4G cell. In an embodiment, the non-VoNR call may be handled as VoNR call by the 5G cell. Furthermore, the on-going non-VoNR call may be handled as VoLTE call by the 4G cell. In an embodiment, the on-going non- VoNR call and the data session may initially be handled by a non 5G cell. In an embodiment, the 5G UE may interchangeably be referred as the UE. In an example, the method may be implemented in the UE. As described above, the UE may be configured to operate in a new radio- stand alone (NR-SA) cellular stack and VoNR may not be supported.

At step 302, the method includes, detecting a requirement to handover the on-going non-VoNR call and a data session. In an embodiment, the handover of the on-going non-VoNR call and the data session may be performed from a non-5G cell to the 5G cell. In an embodiment, the handover may detected upon identification of an on-going call established as a non-VoNR call. In an embodiment, the non-VoNR call may be a VoWiFi call. In an embodiment, the requirement to handover the on-going VoWiFi call may be detected based on monitoring one or more of a VoWiFi client associated with the on-going non-VoNR call and the data session active on the non-5G cell.

Further, in response to monitoring, the method may include determining that a value associated with the VoWiFi client is equal to a pre-determined threshold. In an embodiment, the value may be related to a signal quality during the Vo-WiFi call. In an embodiment, the value related to the signal quality may decline upon moving out of the UE from an area with a WiFi coverage to another area with 5G NR SA coverage. In an embodiment, the non-5G cell may be associated with a WiFi service. In an embodiment, where it is determined that the value associated with the VoWiFi client is equal to a pre-determined threshold, the UE may switch from the WiFi coverage to the cellular domain. In an embodiment, the pre-determined threshold may be one or more of a UE implementation, and an operator defined threshold. In an embodiment, the pre-determined threshold may correspond to detecting a requirement for performing a handover.

At step 304, the method includes, sending a handover request for the on-going non-VoNR call to the 5G cell. In an embodiment, the handover request may be sent upon detecting that the value related to the signal quality is equal to the pre-determined threshold. In an embodiment, the handover may be set such that the handover is performed prior to the signal quality declining and resulting in a call drop. In an embodiment, sending the handover request may be based on transmitting a PDU session request to the 5G cell. In an embodiment, the PDU session request may include a session identification (ID) associated with a previous PDU session between the UE and the non-5G cell.

At step 306, the method includes, detecting whether the non-VoNR call is handled by the 5G cell as a VoNR call or not. Upon detection, the method may move towards one of a

step

308a and 308b.

Continuing with the above embodiment, at step 308a, the method includes sending a request to handover the data session from the non-5G cell to the 5G cell. In an embodiment, the request to handover the data session may be sent in response to determining that the non-VoNR call is handled by the 5G cell as a VoNR call.

In an embodiment, for handling the non-VoNR call by the 5G cell as a VoNR call, the UE may be configured to establish a 5G mobility management (MM) context with a network during a registration procedure with the 5G cell. Based on that, a NAS signaling connection may be established. Furthermore, the UE may be configured to establish a PDU session setup for an IMS access and the PDU session may be accepted. In an embodiment, establishing the PDU session may include a system management function (SMF) selection by an access and mobility management function (AMF), a policy session setup with a policy control function (PCF) and a user plane function (UPF) selection by the AMF. Upon acceptance of the PDU session, an IMS signaling bearer may be established in response to occurrence of an IMS registration procedure between the UE and an IMS server.

Moving forward, when non-VoNR call is triggered, a session initiation protocol (SIP) INVITE may be triggered for the call and the SIP INVITE may be responded by a server, followed by a QoS flow identifier (QFI) bearer setup between a gNB and proxy-call session control function (P-CSCF) nodes. Moving forward, the gNB may be configured to establish dedicated bearers for the non-VoNR call and the non-VoNR call may be considered connected, post a QoS flow establishment. Furthermore, establish the dedicated bearers may indicate that a connection is successful.

In an embodiment, determining that the non-VoNR call is handled by the 5G cell as the VoNR call may be based on determining an occurrence of one or more of the PDU session and a QoS flow establishment on the 5G cell. In an embodiment, where the non-VoNR call is handled as the VoNR call, the UE may be camped with the 5G cell and a number of call related resources and a number of bearers may be provided by the 5G cell. In an embodiment, the data session may also be established on the 5G cell immediately upon moving of the UE out of the WiFi coverage.

Furthermore, at step 308b, the method may include delaying of sending a request to handover the data session from the non-5G cell to the 5G cell. In an embodiment, the delay may be caused upon determining that the non-VoNR call is handled by the 5G cell using an EPSFB procedure. In an embodiment, the sending the request to handover the data session from the non-5G cell to the 5G cell may be delayed until the non-VoNR call is established on a 4G cell. In an embodiment, the non-VoNR call may be handled by an EPSFB procedure when the 5G cell may not be capable to provide the number of resources and the number of bearers to the UE for continuing the non-VoNR call over the NR SA. In an embodiment, the EPSFB procedure may be utilized by redirecting the UE to the 4G cell. In an embodiment, upon being redirected towards to the 4G cell, the non-VoNR call may be handled as a VoLTE call. In an embodiment, the data session may also be established on the 4G cell immediately upon moving of the UE out of the WiFi coverage.

In an embodiment, for performing the EPSFB procedure, the UE may be configured to establish a 5G MM context with a network during a registration procedure with the 5G cell. Based on that, a NAS signaling connection may be established. Furthermore, the UE may be configured to establish a PDU session setup for an IMS access and the PDU session may be accepted. In an embodiment, establishing the PDU session may include a SMF selection by an AMF, a policy session setup with a PCF and a UPF selection by the AMF. Upon acceptance of the PDU session, an IMS signaling bearer may be established in response to occurrence of an IMS registration procedure between the UE and an IMS server.

Moving forward, when non-VoNR call is triggered, an SIP INVITE may be triggered for the call and the SIP INVITE may be responded by a server, followed by a QFI bearer setup between a gNB and P-CSCF nodes. Continuing with the above embodiment, the gNB may configured a UE fallback for EPSFB with a redirected carrier frequency of a 4G cell, and the UE may be redirected to LTE. Subsequently, the UE may be configured to latch on the LTE and signal for one of a tracking area update (TAU) and an attach procedure with a PDN connectivity request in the 4G cell.

Furthermore, an mobility management entity (MME) may be configured to modify the bearer with a packet data wetwork gateway (PGW) through a serving gateway (SGW) and the MME may be configured to further notify a RAT change indication to the IMS server via the PGW, the PCF and the P-CSCF. Furthermore, an eNB associated with the LTE may be configured to set up dedicated bearers for a voice session setup and the non-VoNR call may be connected. In an embodiment, a connection of the non-VoNR call may indicate that an EPSFB call is connected based on performing the EPSFB procedure.

Subsequently, in an embodiment, where it is determined that the UE on the VoWiFi call is out of the area with the WiFi coverage to the 5G cell, the Vo-WiFi call may be continued on one of the 5G cell and the 4G cell. In an embodiment, the Vo-WiFi call may be continued on the 5G cell as the VoNR call and the Vo-WiFi call may be continued on the 4G cell upon being redirected to LTE as the VoLTE call based on a network capability.

Furthermore, the UE may include one or more applications using the WiFi services in the form of foreground data and background data along with the Vo-WiFi call. In an embodiment, the one or more applications may be installed on the UE and the one or more applications may also be handled by an internet service in the UE on the 5G cell.

Moving forward, during a transfer from WiFi services to the internet on the UE, along with continuation of the Vo-WiFi call and data services for one or more of pending applications, the foreground data and the background data using the one or more applications in the UE shall be performed and corresponding data sessions may be established on the 5G using a number of PDU sessions. In an embodiment, the UE may initiate a release request for the number of PDU sessions before mobilizing towards the LTE resulting in an additional overhead in signaling and latency.

Fig. 4 illustrates an operational flow diagram 400 depicting a process for handling data session associated with a 5G UE, in accordance with an embodiment of the present subject matter. In an embodiment, handling the data session may include performing a handover of the data session and an on-going non-VoNR call to a 5G cell. In an embodiment, the non-VoNR call and the data session may be associated with a non-5G cell. In an embodiment, the non-VoNR call may be a Vo-WiFi call. Upon the handover, handling of the data session may be based on continuing the data session on one of a 5G cell and a 4G cell. In an embodiment, the on-going non-VoNR call may also be handled by one of the 5G cell and the 4G cell. In an embodiment, the non-VoNR call may be handled as VoNR call by the 5G cell. Furthermore, the on-going non-VoNR call may be handled as VoLTE call by the 4G cell. In an embodiment, the 5G UE may interchangeably be referred as the UE. In an example, the method may be implemented in the UE. As described above, the UE may be configured to operate in a NR-SA cellular stack and VoNR may not be supported.

Continuing with the above embodiment, at step 402, the process may include determining that a signal quality associated with the Vo-WiFi client is equal to a pre-determined threshold. In an embodiment, the pre-determined threshold value may indicate that the signal quality of the Vo-Wi-fi call is low. In an embodiment, the value related to the signal quality may decline upon moving out of the UE from an area with a WiFi coverage to another area with 5G NR SA coverage. In an embodiment, the pre-determined threshold may be one or more of a UE implementation, and an operator defined threshold. In an embodiment, the pre-determined threshold may correspond to detecting a requirement for performing a handover.

Subsequent to determining that the signal quality value is equal to the pre-determined threshold value, at step 404, the process may proceed towards initiating the handover of the VoWi-Fi call and the data session from the non-5G cell to the 5G cell. In an embodiment, initiating the handover may include sending a handover request for the on-going non-VoNR call to the 5G cell. In an embodiment, the handover request may be sent by the UE. Furthermore, the process may include performing a successful handover of the Wi-Fi call and the data session from the non-5G cell to the 5G cell. In an embodiment, sending the handover request may be based on transmitting a PDU session request to the 5G cell. In an embodiment, the PDU session request may include a session ID associated with a previous PDU session between the UE and the non-5G cell.

Continuing with the above embodiment, upon a successful handover, at the step 406, the process may proceed towards determining a number of PDU sessions active on the network. In an embodiment, the number of PDU sessions may be active in one of an application layer and an upper layer of the UE. In an embodiment, the upper layers may include a radio interface layer (RIL) and non-access stratum (NAS). In an embodiment, the number of PDU sessions may be associated with at least one service in the UE. In an embodiment, the at least one service may be at least one application installed in the UE.

Moving forward, at step 408, the process may include detecting a requirement to establish a new PDU session in response to determining the number of PDU sessions active on the network. In an embodiment, the new PDU session may be associated with a data-based service other than the non-VoNR call on the UE. In an embodiment, the new PDU session may be established for the data session prior to the data session switching to the 5G cell. In an embodiment, where it is determined that the PDU session is required to be established, the process may proceed towards step 410a. In an embodiment, where it is determined that the PDU session is not required to be established, the process may proceed towards step 410b.

Continuing with the above embodiment, at step 410a, the process may include indicating an upper layer/interface of the UE for holding the number of PDU sessions in response to determining the requirement to establish the new PDU session. In an embodiment, the process may further include initiating an EPSFB timer in response to holding of the number of PDU sessions. In an embodiment, the EPSFB timer may be initiated for a pre-determined amount of time calculated based on a number of parameters. Examples of the number of parameters may include, but are not limited to, user implementation, field trails, negotiations based on operator parameters.

Subsequently, at step 412a, the process may include determining whether an "IMS PDU SESSION MODIFICATION CMD" command is received by the UE. In an embodiment, receiving the command may indicate that the non-VoNR call may be established on NR as the VoNR call. In an embodiment, the determining may be performed by the UE. In an embodiment, where it is determined that the "IMS PDU SESSION MODIFICATION CMD" is received, the process may proceed towards step 414a. At step 414a, the process may include triggering an initiation of a PDU session establishment in response to occurrence of one of receiving "IMS PDU SESSION MODIFICATION CMD" before an expiry of the EPSFB timer, and expiry of the EPSFB timer prior to receiving a re-direction command to LTE. In an embodiment, the PDU session may be established for the at least one service requiring a data service.

In an embodiment, where it is determined that the "IMS PDU SESSION MODIFICATION CMD" is not received, the process may proceed towards step 414b. At step 414b, the process may include determining whether the EPSFB timer expired prior to receiving a re-direction command to Long Term Evolution (LTE). In an embodiment, where it is determined that the EPSFB timer expired prior to receiving the re-direction command, the process may proceed towards performing the step 414a.

In an embodiment, where it is determined that the EPSFB timer is not expired prior to receiving the re-direction command, the process may include determining at step 416a whether the "IMS PDU SESSION MODIFICATION CMD" is received or not. In an embodiment, where it is determined that the "IMS PDU SESSION MODIFICATION CMD" is not received, the process may backtrack to step 412a indicating that the timer is not expired. In an embodiment, where it is determined that the "IMS PDU SESSION MODIFICATION CMD" is received, the process may proceed towards, step 418.

At step 418, the process may include performing an EPS fallback in response to receiving a re-direction command to LTE prior to expiry of the EPSFB timer. In an embodiment, the EPS fallback may be performed by camping on to the 4G cell from the 5G cell in response to receiving a re-direction command to the 4G cell from the network prior to expiry of the EPSFB timer. In an embodiment, the re-direction command may include comprises frequency details associated with the 4G cell. Upon a successful EPS fallback, a call bearer may be established. Further, the process may include receiving an EPSFB configuration from a network. In an embodiment, the EPSFB configuration may be received by the UE. In an embodiment, the EPSFB configuration may include a radio resource controller (RRC) release message from the network. In an embodiment, the RRC release message may include redirected carrier information associated with the 4G cell. Moving forward, the process may include sending a handover request to the 4G cell based on the EPSFB configuration by the UE. In an embodiment, upon determining that the EPSFB is successful and one or more call bearers is set, the UE may be configured to establish the one or more call bearers for other internet services from applications on the 4G and stop the timer.

Continuing with the above embodiment, the process may include waiting for a confirmation for the handover to the 4G cell for a pre-defined timer period. Subsequently, the process may include sending the handover request for the data session to the 5G cell in response to not receiving the EPEFB configuration within the pre-defined timer period. Furthermore, the process may include establishing the PDU session for the data session upon sending the handover request for the data session to the 5G cell

At step 420, the process may terminate after stoppage of the timer.

Continuing with the above embodiment, at step 410b, the process may include triggering an IMS PDU establishment request in response to determining a requirement for an IMS PDU session for the non-VoNR call as the at least one service that required the data services may be inactive at that point of time.

Fig. 5 illustrates a schematic block diagram 500 depicting to handle a data session in a 5G UE, in accordance with an embodiment of the present subject matter. In an embodiment, the 5G UE may be referred as a UE. Examples of the UE may include, but are not limited to a personal computer (PC), a laptop, and a smartphone. In an embodiment, handling of the data session may be based on continuing the data session on one of a 5G cell and a 4G cell. In an embodiment, an on-going non- VoNR call may also be handled by one of the 5G cell and the 4G cell. In an embodiment, the non-VoNR call may be handled as VoNR call by the 5G cell. Furthermore, the on-going non-VoNR call may be handled as VoLTE call by the 4G cell. In an embodiment, the on-going non- VoNR call and the data session may initially be handled by a non 5G cell. In an embodiment, the 5G UE may interchangeably be referred as the UE. In an example, the method may be implemented in the UE. As described above, the UE may be configured to operate in a NR-SA cellular stack and VoNR may not be supported.

At step 502, the method includes, detecting a need to handover an ongoing non-VoNR call and a data session from a first cell to a 5G cell. In an embodiment, the non-VoNR call may be a VoWiFi call. In an embodiment, the non-VoNR call may interchangeably be referred as the VoWiFi call.

At step 504, the method includes, sending a request to establish a call bearer with the 5G cell for the non VoNR call. In an embodiment, the request may be sent by the UE to a network. In an embodiment, the UE while moving out of WiFi coverage, may try to establish or handover the non-VoNR call to a cellular domain such as NR to continue seamless call experience.

At step 506, the method includes, ascertaining if the call bearer with the 5G cell for the non-VoNR call is successfully established. In an embodiment, where it is determined that the call bearer with the 5G cell for the non-VoNR call is successfully established, the method may proceed towards step 508a. In an embodiment, where it is determined that the call bearer with the 5G cell for the non-VoNR call is not successfully established, the method may proceed towards step 508b.

Continuing with the above embodiment, at step 508a, the method includes sending a request to establish a PDU session for the data session on the 5G cell in response to determining that the call bearer is successfully established. Moving forward, upon successful establishment of the PDU session, in an embodiment, the method may include determining that the non-VoNR call is ongoing while the UE is registered on a 5G-SA as the 5G cell and the VoNR is not supported.

Continuing with the above embodiment, in response to determining that the VoNR is not supported and the VoNR call may be active on the 5G cell, the method may include awaiting weakening of WiFi coverage till reaching of a Vo-WiFi client threshold for a cellular (NR) handover (HO). In an embodiment, the WiFi coverage may be a signal quality associated with the VoWiFi call defined as the non-VoNR call. In an embodiment, the Vo-WiFi client threshold may be a threshold value associated with the signal quality of the Vo-WiFi call.

Subsequently to waiting for the signal quality associated with the Vo-WiFi call to reach the threshold value, the method may proceed towards initiating a request for an ONLY IMS PDU session establishment, if there are multiple other applications requiring internet services, thereby skipping PDU establishment procedure for other applications that use an internet bearer. In an embodiment, the request may be sent by the UE. Furthermore, the method may include awaiting by the UE for a time interval T1 in milliseconds depending on UE implementation for upper layers to indicate a requirement of the data session. In an embodiment, the time interval T1 milliseconds may be configured on a EPSFB timer.

Continuing with the above embodiment, the method may include resorting to an EPS fallback by the UE without having to initiate data sessions. In an embodiment, the EPS fallback may be initiated in response to the UE receiving a redirection command to the 5G cell before an expiry of the EPSFB timer. Subsequently, the method may include initiating other PDU session establishment processes by the UE. In an embodiment, the other PDU session processes may be initiated in response to determining one of receiving an IMS PDU SESSION MODIFICATION CMD prior to expiry of the EPSFB timer expiry and the expiry of the EPSFB timer before the redirection

Furthermore, at step 508b, the method includes sending a request to establish the PDU session for the data session on a second cell in response to determining that the call bearer with the 5G cell for the VoNR call is not successfully established.

Fig. 6 illustrates an operational flow diagram 600 depicting a process for a UE continuing to establish remaining sessions, in accordance with an embodiment of the present subject matter. At step 602, the UE in LTE coverage with a Vo-WiFi ongoing alongside an active data connection. At step 604, the UE enters SA coverage and hand-over happens from LTE to NR while the UE may still be on Wi-Fi. At step 606, the Wi-Fi coverage becomes weak and a Vo-WiFi client threshold may be hit. At step 608, the UE may register over a SA cell, and at step 610, the UE may attempt to establish a PDU session for IMS by initiating a request while holding other sessions in WAIT state. At step 612, if a network acknowledges the request by the UE to establish the PDU session, at step 616, the UE continues to establish PDU sessions for other ongoing data activities. At step 612, if the request is rejected by the network, at step 614, an EPS fallback may take place without a release of the PDU sessions to be released and contexts transferred to MME by the network.

In an embodiment, where it is determined that a Wi-Fi coverage is poor and the UE is moving to the SA, the UE may initiate a PDU session establishment request for the IMS only. In an embodiment, where PDU session establishment request is accepted, the UE continue to establish the remaining PDU sessions.

Figure 7 illustrates an operational flow diagram 700 depicting another process for a UE continuing to establish remaining sessions, in accordance with an embodiment of the present subject matter.

At step 702, the UE in LTE coverage with Vo-WiFi ongoing alongside an active data connection. At step 704, the UE may enter an SA coverage and a handover may take place from LTE to NR while the UE may still be on a WiFi. At step 706, the WiFi coverage becomes weak and Vo-WiFi client threshold is hit. At step 708, the UE may register over a 5G SA cell, and at step 710, the UE further may attempt to establish a number of PDU sessions corresponding to current PDN connections such as an IMS, and an internet in one NAS message only. The UE may also piggyback a number of PDU session establishment messages in one RRC message and send it to network. Further, a 5GC network may prioritize a IMS PDU session, and establish the IMS PDU session. Furthermore, at step 712 and step 714, the 5GC network may gradually establish other PDU sessions, based on an IMS PDU session establishment accept. In an embodiment, at step 712, where it is determined that the PDU session for the IMS is rejected by the network, at step 716, an EPS fallback may take place. As other PDU sessions may not be yet established, contexts related to the other PDU sessions may not be released.

Fig. 8 illustrates an operational flow diagram 800 depicting a process for a UE to initiate request for IMS, in accordance with an embodiment of the present subject matter. In an embodiment, at step 802, the UE may initiate a request for IMS and upon acceptance by the network, the UE may establish other PDU sessions instead of establishing PDU sessions for at least one service in the UE preventing unnecessary set-up of PDU sessions for services supported on NR to be moved to LTE to continue voice services.

At step 804, a Vo-WiFi call may be triggered and data may be ongoing over a WiFi stack. At step 806, a Wi-Fi coverage may become weak and a Vo-WiFi client threshold is hit for a cellular hand over (HO). At step 808, the UE may initiate a request for IMS PDU session establishment, and at step 810, the UE further may attempt to establish PDU session for IMS keeping others on WAIT. At step 812, ff the request is accepted, at step 814, the UE may further request for an establishment of other PDU sessions. At step 812, if request for an establishment of other PDU sessions is rejected, At step 816, the UE may perform an EPS fallback without having to initiate other sessions.

Fig. 9 illustrates an operational flow diagram 900 depicting a process for a UE to initiate request for IMS, in accordance with an embodiment of the present subject matter. At step 902 and step 904, Vo-WiFi call is triggered and data is ongoing over WI-FI stack. At step 906, a WiFi coverage may become weak and a Vo-WiFi client threshold is hit for cellular HO. At step 908 and step 910, the UE may attempt to establish a number of PDU sessions corresponding to current connections such as an IMS, and an internet in one NAS message only. The UE may also piggyback a number of PDU session establishment messages in one RRC message and send the number of PDU session establishment messages to the network saving a signalling. A 5GC network may prioritize IMS PDU session, and establish the IMS PDU session. At step 912 and 914, the 5GC Network may gradually establish other PDU sessions, based on an IMS PDU session establishment accept. At step 912, if the 5GC network rejects a PDU session for the IMS, at step 916, an EPS fallback may take place. As other PDU sessions may not be yet established, contexts related to the other PDU sessions may not be released.

Fig. 10 illustrates an operational flow diagram 1000 for depicting a process for a UE to attempt to establish a PDU session for an IMS instead of establishing active PDU sessions, in accordance with an embodiment of the present subject matter. When a HO is triggered, the UE may first attempt to establish the PDU session for the IMS instead of establishing all active PDU sessions in parallel. If the request the PDU session for the IMS is rejected, the UE may fall back to LTE without trying to establish other sessions.

At Step 1002, a Vo-LTE call may be ongoing along with data. At step 1004, the UE may check that the UE is in a 5G SA coverage as co-located cells include LTE+SA coverage. At step 1006, the UE may handover to the 5G SA, and at step 1008, the UE may further try to establish the PDU session for VONR/IMS. At step 1010, if a request to establish the PDU session is accepted by a network, at step 1012, the UE may proceed with an establishment of other PDU sessions. At step 1010, if the request is rejected, at step 1014, the UE may fall back to an EPS without having to waste resources over other services.

Fig. 11 illustrates an operational flow diagram 1100 for depicting another process for a UE to attempt to establish PDU session for IMS instead of establishing active PDU sessions, in accordance with an embodiment of the present subject matter.

In an embodiment, at step 1102, a Vo-LTE call may be ongoing along with data. At step 1104 and step 1106, the UE may be configured to check that the UE is in 5G SA coverage as co-located cells include LTE+SA coverage. At step 1108, the UE may register on a 5GC first. Furthermore, at step 1110, the UE may check for an IMS-VoPS-3GPP indication in a 5GS network feature support in a registration accept message. If IMS-VoPS-3GPP is 1, at step 1112, the UE may only then attempt to establish all PDU sessions corresponding to current PDN connections such as an IMS, and an internet in one NAS message only. The UE may also piggyback a number of PDU session establishment messages in one RRC message and send the number of PDU session establishment messages to the network saving a signalling overhead. The 5GC network may further prioritize the IMS PDU session, and establish the IMS PDU session first. At step 1114 and step 1116, the 5GC Network may then gradually establish other PDU sessions, based on an IMS PDU session establishment accept. At step 1114, if the network rejects the PDU session for IMS, at step 1118, an EPS fallback ay take place. As other PDU sessions may not be yet established, contexts related to the other PDU sessions may not be released.

Fig. 12 is a diagram illustrating the configuration of a terminal 1200 in a wireless communication system according to an embodiment of the present subject matter. The configuration of Fig. 12 may be understood as a part of the configuration of the terminal 1200. Hereinafter, it is understood that terms including "unit" or "er" at the end may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

Referring to Fig. 12, the terminal 1200 may include a processer 1202 (e.g., at least one processor), a storage unit 1204 (e.g., storage), data 1206 and, module(s) 1208, and a communication unit 1210 (e.g., communicator or communication interface). By way of example, the terminal 1200 may be a User Equipment, such as a cellular phone or other device that communicates over a plurality of cellular networks (such as a 4G, a 5G or pre-5G network or any future wireless communication network). In an embodiment, the processer 1202, the storage unit 1204, the data 1206, and the module(s) 1208, and the communication unit 1210 may be communicably coupled with one another.

As would be appreciated, the terminal 1200, may be understood as one or more of a hardware, a software, a logic-based program, a configurable hardware, and the like. In an example, the processer 1202 may be a single processing unit or a number of units, all of which could include multiple computing units. The processor may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, processor cores, multi-core processors, multiprocessors, state machines, logic circuitries, application-specific integrated circuits, field-programmable gate arrays and/or any devices that manipulate signals based on operational instructions. Among other capabilities, the processer 1202 may be configured to fetch and/or execute computer-readable instructions and/or data 1206 stored in the storage unit 1204.

In an example, the storage unit 1204 may include any non-transitory computer-readable medium known in the art including, for example, volatile memory, such as static random access memory (SRAM) and/or dynamic random access memory (DRAM), and/or non-volatile memory, such as read-only memory (ROM), erasable programmable ROM (EPROM), flash memory, hard disks, optical disks, and/or magnetic tapes. The storage unit 1204 may store data, such as a basic program, an application program, configuration information, and the like for operating the terminal 1200. The storage unit 1204 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The storage unit 1204 may include the data 1206. In addition, the storage unit 1204 may provide data stored therein in response to a request from the processer 1202.

The data 1206 serves, amongst other things, as a repository for storing data processed, received, and generated by one or more of, the processer 1202, the storage unit 1204, the module(s) 1208, and the communication unit 1210.

The module(s) 1208, amongst other things, may include routines, programs, objects, components, data structures, etc., which perform particular tasks or implement data types. The module(s) 1208 may also be implemented as, signal processor(s), state machine(s), logic circuitries, and/or any other device or component that manipulate signals based on operational instructions.

Further, the module(s) 1208 may be implemented in hardware, instructions executed by at least one processing unit, for e.g., processer 1202, or by a combination thereof. The processing unit may be a general-purpose processor which executes instructions to cause the general-purpose processor to perform operations or, the processing unit may be dedicated to performing the required functions. In another aspect of the present disclosure, the module(s) 1208 may be machine-readable instructions (software) which, when executed by a processor/processing unit, may perform any of the described functionalities.

In some example embodiments, the module(s) 1208 may be machine-readable instructions (software) which, when executed by a processor/processing unit, perform any of the described functionalities.

The processer 1202 may control overall operations of the terminal 1200. For example, the processer 1202 may transmit and receive a signal via the communication unit 1210. Further, the processer 1202 records data in the storage unit 1204 and reads the recorded data. The processer 1202 may perform the functions of a protocol stack required by a particular communication standard. To this end, the processer 1202 may include at least one processor or micro-processor or may be a part of the processor. Also, a part of the communication unit 1210 and the processer 1202 may be referred to as a communication processor (CP).

Referring to fig. 1, the processer 1202 may be configured to detect a requirement to handover an on-going non- VoNR call and a data session from a non-5G cell to a 5G cell. In an embodiment, for detecting the requirement to perform the handover the processor 1202 may be configured to monitor one or more of a VoWiFi client associated with the on-going non-VoNR call and the data session active on the non-5G cell. Furthermore, the processor 1202 may be configured to determine that a value associated with the VoWiFi client is equal to a pre-determined threshold, wherein the value corresponds a signal quality during the WiFi call. In an embodiment, the non-VoNR call may be a VoWiFi call.

12021202Furthermore, the processor 1202 1210may be configured to send a handover request for the on-going non-VoNR call to the 5G cell through the communication unit 1210. In an embodiment, the communication unit 1210 may be configured to send the handover request by transmitting a PDU session request to the 5G cell. In an embodiment, the PDU session request may include a ID associated with a previous PDU session between the UE and the non-5G cell.

Moving forward, upon sending the handover request, the processor 1202 may be configured to detect whether the non-VoNR call is handled by the 5G cell as a VoNR call or not. Moving forward, the 1210processor 1202 may be configured to send a request to handover the data session from the non-5G cell to the 5G cell upon determining by the processer 1202 that the non-VoNR call is handled by the 5G cell as a VoNR call through the communication unit 1210. In an embodiment, detecting that the non-VoNR call is handled by the 5G cell as the VoNR call may be based on determining an occurrence of one or more of a PDU session and a QoS flow establishment on the 5G cell.

In an embodiment, for handling the non-VoNR call by the 5G cell as a VoNR call, the processor 1202 may be configured to establish a 5G MM context with a network during a registration procedure with the 5G cell. Based on that, a NAS signaling connection may be established. Furthermore, the processor 1202 may be configured to establish a PDU session setup for an IMS access and the PDU session may be accepted. In an embodiment, establishing the PDU session may include a SMF selection by an AMF, a policy session setup with a PCF and a UPF selection by the AMF. Upon acceptance of the PDU session, an IMS signaling bearer may be established in response to occurrence of an IMS registration procedure between the UE and an IMS server.

Moving forward, when non-VoNR call is triggered, an SIP INVITE may be triggered for the call and the SIP INVITE may be responded by a server, followed by a QFI bearer setup between a gNB and P-CSCF nodes. Moving forward, the gNB may be configured to establish dedicated bearers for the non-VoNR call and the non-VoNR call may be considered connected, post a QoS flow establishment. Furthermore, establish the dedicated bearers may indicate that a connection is successful.

In an embodiment, the processor 1202 may be configured to delay sending the request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an EPSFB procedure.

In an embodiment, for performing the EPSFB procedure, the processor 1202 may be configured to establish a 5G MM context with a network during a registration procedure with the 5G cell. Based on that, a NAS signaling connection may be established. Furthermore, the UE may be configured to establish a PDU session setup for an IMS access and the PDU session may be accepted. In an embodiment, establishing the PDU session may include a SMF selection by an AMF, a policy session setup with a PCF and a UPF selection by the AMF. Upon acceptance of the PDU session, an IMS signaling bearer may be established in response to occurrence of an IMS registration procedure between the UE and an IMS server.

Moving forward, when non-VoNR call is triggered, an SIP INVITE may be triggered for the call and the SIP INVITE may be responded by a server, followed by a QFI bearer setup between a gNB and P-CSCF nodes. Continuing with the above embodiment, the gNB may configure a UE fallback for EPSFB with a redirected carrier frequency of a 4G cell, and the UE may be redirected to LTE. Subsequently, the processor 1202 may be configured to latch on the LTE and signal for one of a TAU and an attach procedure with a PDN connectivity request in the 4G cell.

Furthermore, an MME may be configured to modify the bearer with a PGW through a SGW and the MME may be configured to further notify a RAT change indication to the IMS server via the PGW, the PCF and the P-CSCF. Furthermore, an eNB associated with the LTE may be configured to set up dedicated bearers for a voice session setup and the non-VoNR call may be connected. In an embodiment, a connection of the non-VoNR call may indicate that an EPSFB call is connected based on performing the EPSFB procedure.

In an embodiment, sending the request to handover the data session from the non-5G cell to the 5G cell may be delayed until the non-VoNR call is established on a 4G cell. 1202

Referring to fig. 3, the processer 1202 may be configured to detect a need to handover an ongoing non-VoNR call and a data session from a first cell to a 5G cell. In an embodiment, the non-VoNR call may be a VoWiFi call. In an embodiment, the non-VoNR call may interchangeably be referred as the VoWiFi call. Furthermore, the communication unit 1210 may be configured to send a request to establish a call bearer with the 5G cell for the non VoNR call. In an embodiment, the request may be sent by the UE to a network.

Continuing with the above embodiment, the processer 1202 may be configured to ascertain if the call bearer with the 5G cell for the non-VoNR call is successfully established. In an embodiment, where it is determined that the call bearer with the 5G cell for the non-VoNR call is successfully established, the communication unit 1210 may be configured to send a request to establish a PDU session for the data session on the 5G cell. Furthermore, the processer 1202 may be configured to determined= that the non-VoNR call is ongoing while the UE is registered on a 5G-SA as the 5G cell and the VoNR is not supported. Furthermore, the processer 1202 may be configured to await a weakening of WiFi coverage till reaching of a Vo-WiFi client threshold for a cellular (NR) handover (HO). In an embodiment, the WiFi coverage may be a signal quality associated with the VoWiFi call defined as the non-VoNR call. In an embodiment, the Vo-WiFi client threshold may be a threshold value associated with the signal quality of the Vo-WiFi call.

Subsequently, the communication unit 1210 may be configured to initiate a request for an ONLY IMS PDU session establishment. Furthermore, the processer 1202 may be configured to wait for a time interval T1 milliseconds for upper layers to indicate a requirement of the data session. In an embodiment, the time interval T1 milliseconds may be configured on a EPSFB timer.

Continuing with the above embodiment, the processer 1202 may be configured to resort to an EPS fallback without having to initiate data sessions. In an embodiment, the EPS fallback may be initiated in response to the UE receiving a redirection command to the 5G cell before an expiry of the EPSFB timer. Subsequently, the communication unit 1210 may be configured to initiate other PDU session establishment processes by the UE. In an embodiment, the other PDU session processes may be initiated in response to determining by the processer 1202 one of receiving an IMS PDU SESSION MODIFICATION CMD prior to expiry of the EPSFB timer expiry and the expiry of the EPSFB timer before the redirection.

In an embodiment, the processer 1202 may be configured to ascertain that the call bearer with the 5G cell for the non-VoNR call is not successfully established. Furthermore, the communication unit 1210 may be configured to send a request to establish the PDU session for the data session on a second cell.

While specific language has been used to describe the present disclosure, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.

Claims

A method for handling a data session associated with a 5G user equipment (UE), the method comprising:

detecting a requirement to handover an on-going non-voice over new radio (non-VoNR) call and a data session from a non-5G cell to a 5G cell;

sending a handover request for the on-going non-VoNR call to the 5G cell; and

detecting whether the non-VoNR call is handled by the 5G cell as a VoNR call or not;

performing one of:

sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell as a VoNR call; and

delaying of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an Evolved Packet Core Fall Back (EPSFB) procedure.
The method as claimed in claim 1, wherein the non-VoNR call is a voice over wireless-fidelity (VoWiFi) call.
The method as claimed in claim 1, wherein the requirement to handover is detected based on:

monitoring one or more of a VoWiFi client associated with the on-going non-VoNR call and the data session active on the non-5G cell;

determining that a value associated with the VoWiFi client is equal to a pre-determined threshold, wherein the value corresponds a signal quality during the Vo-WiFi call.
The method as claimed in claim 1 or claim 3, further comprising:

determining a plurality of PDU sessions active on the network, wherein the plurality of PDU sessions is associated with at least one service in the UE;

detecting a requirement to establish a new PDU session in response to determining the plurality of PDU sessions active on the network, wherein the new PDU session is associated with a data-based service other than the non-VoNR call;

indicating an upper layer of the UE for holding the plurality of PDU sessions in response to determining the requirement to establish the new PDU session;

initiating an Evolved Packed System (EPS) Fall Back (EPSFB) timer in response to holding of the plurality of PDU sessions, wherein the EPSFB timer is initiated for a pre-determined amount of time calculated based on a plurality of parameters; and

performing at least one of:

triggering an initiation of a PDU session establishment in response to occurrence of one of receiving "IMS PDU SESSION MODIFICATION CMD" before an expiry of the EPSFB timer, and expiry of the EPSFB timer prior to receiving a re-direction command to LTE; and

performing an EPS fallback by camping on to a 4G cell from the 5G cell in response to receiving a re-direction command to the 4Gcell from the network prior to expiry of the EPSFB timer, wherein the re-direction command comprises frequency details associated with the 4G cell,

wherein the new PDU session is established for the data session prior to the data session switching to the 5G cell.
The method as claimed in claim 4, further comprising:

triggering an IMS PDU establishment request in response to determining a requirement for an IMS PDU session for the non-VoNR call.
The method as claimed in claim 1, wherein sending the handover request is based on transmitting a protocol data unit (PDU) session request to the 5G cell, wherein the PDU session request comprises a session identification (ID) associated with a previous PDU session between the UE and the non-5G cell,

wherein detecting that the non-VoNR call is handled by the 5G cell as the VoNR call is based on determining an occurrence of one or more of a PDU session and a quality of service (QoS) flow establishment on the 5G cell.
The method as claimed in claim 1, wherein the sending the request to handover the data session from the non-5G cell to the 5G cell is delayed until the non-VoNR call is established on a 4G cell.
The method as claimed in claim 1, further comprising:

receiving an EPSFB configuration comprising a radio resource controller (RRC) release message from the network, wherein the RRC release message comprises redirected carrier information associated with a 4G cell.; sending a handover request to the 4G cell based on the EPSFB configuration; and

waiting for a confirmation for the handover to the 4G cell for a pre-defined timer period.
The method as claimed in claim 8, further comprising:

sending a handover request for the data session to the 5G cell in response to not receiving the EPEFB configuration within the pre-defined timer period; and

establishing a PDU session for the data session upon sending the handover request for the data session to the 5G cell.
A method to handle a data session in a 5G user equipment, the method comprising:

detecting a need to handover an ongoing non-voice over new radio (VoNR) call and a data session from a first cell to a 5G cell;

sending a request to establish a call bearer with the 5G cell for a non VoNR call;

ascertaining if the call bearer with the 5G cell for the non-VoNR call is successfully established; and

performing at least one of

sending a request to establish a protocol data unit (PDU) session for the data session on the 5G cell if the call bearer with the 5G cell for the non-VoNR call is successfully established; and

sending a request to establish the PDU session for the data session on a second cell if the call bearer with the 5G cell for the VoNR call is not successfully established.
The method as claimed in claim 10, wherein in case the non-VoNR call defined by a Vo-WiFi call is ongoing while UE is registered on a 5G-stand alone (SA) as the 5G cell and the VoNR is not supported, the method comprises:

awaiting weakening of WiFi coverage till reaching of a Vo-WiFi client threshold for a cellular handover;

initiating the by the UE a request for an ONLY IMS PDU session establishment and awaiting for a time interval T1 milliseconds defined as EPSFB timer if upper layers indicates requirement of the data session;

resorting to an EPS fallback by the UE without having to initiate data sessions if the UE receives a redirection command to the 5G cell before T1 expiry; and

initiating other PDU session establishment processes by the UE if an IMS PDU SESSION MODIFICATION CMD is received before T1 expiry or if T1 expires before the redirection.
A system for handling a data session associated with a 5G User Equipment (UE), the system comprising:

at least one processor configured to:

detect a requirement to handover an on-going non-Voice over New Radio (non-VoNR) call and a data session from a non-5G cell to a 5G cell;

send a handover request for the on-going non-VoNR call to the 5G cell;

detect whether the non-VoNR call is handled by the 5G cell as a Voice over NR (VoNR) call or not; and

perform one of:

sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell as a VoNR call; and

delaying of sending a request to handover the data session from the non-5G cell to the 5G cell upon determining that the non-VoNR call is handled by the 5G cell using an EPSFB procedure.
The system as claimed in claim 12, wherein the at least one processor is further configured to perform one of the methods described in claims 1 to 9.
A system to handle a data session in a 5G user equipment, the system comprising:

at least one processor configured to:

detect a need to handover an ongoing non-voice over new radio (VoNR) call and a data session from a first cell to a 5G cell;

send a request to establish a call bearer with the 5G cell for a non VoNR call;

ascertain if the call bearer with the 5G cell for the non-VoNR call is successfully established; and

perform at least one of:

send a request to establish a protocol data unit (PDU) session for the data session on the 5G cell if the call bearer with the 5G cell for the non-VoNR call is successfully established, and

send a request to establish the PDU session for the data session on a second cell if the call bearer with the 5G cell for the VoNR call is not successfully established.
The system as claimed in claim 14, wherein the at least one processor is further configured to perform one of the methods described in claims 10 to 11.