Patent Publication Number: US-2022225349-A1

Title: Method for allowing a user equipment (ue) to respond cellular network signalling over a non-cellular radio access network

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The application is a continuation of International Application No. PCT/CN2019/109622, filed on Sep. 30, 2019, entitled “METHOD FOR ALLOWING A USER EQUIPMENT (UE) TO RESPOND CELLULAR NETWORK SIGNALLING OVER A NON-CELLULAR RADIO ACCESS NETWORK”, the entire contents of which are incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to the field of communication systems, and more particularly, to an apparatus and a method for allowing a user equipment (UE) to respond cellular network signalling over a non-cellular radio access network 
     Under the feature of access traffic steering, switching, splitting (ATSSS), Third Generation Partnership Project (3GPP) SA2 working group introduced the concept of a multi-access (MA) protocol data unit (PDU) session. The MA PDU Session, as the name suggest, means that for a session, traffic flows for that session can go on more than one access interfaces. As currently 5G system (5GS) can support 3GPP and non-3GPP access networks, the data for a MA PDU Session can flow uplink (UL) or downlink (DL) through these two access networks. 
     Improved use of the ATSSS feature is desired. 
     SUMMARY 
     An object of the present disclosure is to propose an apparatus and a method for allowing a user equipment (UE) to respond cellular network signalling over a non-cellular radio access network. 
     In a first aspect of the present disclosure, a method for allowing a user equipment (UE) to respond cellular network signalling over a non-cellular radio access network includes the following steps: initiating a service request procedure over non-cellular radio access for a cellular network service; receiving a service reject message in response to the service request procedure; entering an inactive state of the UE over a non-cellular radio access; receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE; responding to the indication over the non-cellular radio access by initiating another service request procedure that activates the non-cellular radio access; entering an active state of the UE over the non-cellular radio access upon activation of the non-cellular radio access which includes a connection and user plane; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE. 
     In a second aspect of the present disclosure, a method for allowing a user equipment (UE) to respond cellular network signalling over a non-cellular radio access network includes the following steps: receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE during an inactive state of the UE over a non-cellular radio access; responding to the indication over the non-cellular radio access by initiating a service request procedure that activates the non-cellular radio access; entering an active state of the UE over the non-cellular radio access upon activation of the non-cellular radio access which includes a connection and user plane; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE. 
     In a third aspect of the present disclosure, a method for allowing a user equipment (UE) to respond cellular network signalling over a non-cellular radio access network includes the following steps: initiating a service request procedure over non-cellular access for a cellular network service; receiving a service reject message in response to the service request procedure; keeping an active state of the UE over a non-cellular radio access after receiving the service reject message; receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE during the active state of the UE over a non-cellular radio access; reactivating the user plane over non-cellular access if that is not active; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE in response to the indication. 
     The disclosed method according to embodiments of the present disclosure may be implemented in an apparatus including a transceiver and a processor. The transceiver is configured to transmit and receive signaling. The processor connected to the transceiver is configured to execute the steps in the disclosed method. 
     According to a fourth aspect of the present disclosure there is provided a non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method of another aspect of the present disclosure. 
     The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise. 
         FIG. 1  illustrates a telecommunication system with an ATSSS feature. 
         FIG. 2  is a block diagram of a user equipment (UE), a base station, a hotspot device, and a network entity device according to an embodiment of the present disclosure. 
         FIG. 3  illustrate a service request procedure initiated by a UE and accepted by a network. 
         FIG. 4  illustrate a service request procedure initiated by a UE and rejected by a network. 
         FIG. 5  illustrate a method for allowing a UE to respond cellular network signalling over a non-cellular radio access network according to an embodiment of the present disclosure. 
         FIG. 6  illustrate a method for allowing a UE to respond cellular network signalling over a non-cellular radio access network according to another embodiment of the present disclosure. 
         FIG. 7  illustrate a method for allowing a UE to respond cellular network signalling over a non-cellular radio access network according to still another embodiment of the present disclosure. 
         FIG. 8  illustrate a method for allowing a UE to respond cellular network signalling over a non-cellular radio access network according to further another embodiment of the present disclosure. 
         FIG. 9  is a block diagram of a system for wireless communication according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure. 
     Fifth-generation (5G) wireless systems are generally a cellular communication system in a frequency range 2 (FR2) ranging from 24.25 GHz to 52.6 GHz, where multiplex transmit (Tx) and receive (Rx) beams are employed by a base station (BS) and/or a user equipment (UE) to combat a large path loss in a high frequency band. Due to the hardware limitation and cost, the BS and the UE might only be equipped with a limited number of transmission and reception units (TXRUs), of which some are for 3GPP access, and some are for non-3GPP access. 
       FIG. 1  shows an architectural illustration a telecommunication system with an ATSSS feature. A UE device  10  connects to access and a mobility management function (AMF)  31  in core network  30  through 3GPP access  20   a  and non-3GPP access  20   b  in a radio access network (RAN)  20 , and further connects to a data network  40 , such as the Internet. Interfaces between two network entities are reference points which are formally defined in 3GPP technical specification (TS) 23.501. Reference points N1, N2, N3, N4, N6, N7, and N11 shown as lines in  FIG. 1  are detailed in the following:
         N1: Reference point between the UE  10  and the AMF  31 .   N2: Reference point between the RAN  20  and the AMF  31 .   N3: Reference point between the RAN  20  and a user plane function (UPF)  35 .   N4: Reference point between a session management function (SMF)  32  and the UPF  35 .   N6: Reference point between the UPF  35  and the data network (DN)  40 .   N7: Reference point between the SMF  32  and a policy control function (PCF)  33 .   N11: Reference point between AMF  31  and SMF  32 .       

     The core network  30  may be a PLMN or a network slice instance of the PLMN. The network  30  further includes a performance measurement function (PMF)  36 , a multipath-transmission control protocol (MPTCP) proxy  34 . The UE  10  includes a MPTCP function  14 , an ATSSS-lower layer (ATSSS-LL) function  15 , and a non-access stratum (NAS)  16 . The 3GPP access  20   a  may include one or more 3GPP radio access base stations. The non-3GPP access  20   b  may include one or more hotspot devices of non-3GPP radio access technologies. 
       FIG. 2  illustrates that, in some embodiments, a UE  10 , a base station  200   a , a hotspot device  200   b , and a network entity device  300  executing a method for allowing a UE to respond cellular network signalling over a non-cellular radio access network according to an embodiment of the present disclosure are provided. Connections between devices and device components are shown as lines and arrows in the  FIG. 3 . The UE  10  may include a processor  11 , a memory  12 , and a transceiver  13 . The base station  200   a  may include a processor  201   a , a memory  202   a , and a transceiver  203   a . The hotspot device  200   b  may include a processor  201   b , a memory  202   b , and a transceiver  203   b . The network entity device  300  may include a processor  301 , a memory  302 , and a transceiver  303 . Each of the processors  11 ,  201   a ,  201   b , and  301  may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of radio interface protocol may be implemented in the processors  11 ,  201   a ,  201   b , and  301 . Each of the memory  12 ,  202   a ,  202   b , and  302  is operatively stores a variety of program and information to operate a connected processor. Each of the transceiver  13 ,  203   a ,  203   b , and  303  is operatively coupled with a connected processor, transmits and/or receives a radio signal. 
     The 3GPP access  20   a  may include one or more base stations  200   a . The non-3GPP access  20   b  may include one or more hotspot devices  200   b . Each of the network entities, such as AMF  31 , SMF  32 , PCF  33 , MPTCP proxy  34 , UPF  35 , and PMF  36 , in network  30  or any combination of the network entities can be implemented in one or more instances of the network entity device  300 . 
     Each of the processor  111 ,  201   a ,  201   b , and  301  may include an application-specific integrated circuit (ASIC), other chipsets, logic circuit and/or data processing devices. Each of the memory  12 ,  202   a ,  202   b , and  302  may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and/or other storage devices. Each of the transceiver  13 ,  203   a ,  203   b , and  303  may include baseband circuitry to process radio frequency signals. 
     When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in a memory and executed by the processors. The memory can be implemented within a processor or external to the processor, in which those can be communicatively coupled to the processor via various means are known in the art. 
     The choice of which access network certain traffic flows or quality of service (QoS) flows go through is guided by available policy called ATSSS rules. ATSSS rule for each MA PDU Session is made available to UE side for UL traffic and/or QoS flows and the network (NW) side for DL traffic and/or QoS flows. 
     Data traffic, like all DL data traffic for the UE and UL for the network, required the availability of user plane resources, also known as dedicated radio bearers (DRBs). When a MA PDU Session is established, user plane resources can likewise be allocated or at least some of these user plane resources are allocated at that establishment time, and the rest can be allocated on a demand basis. Alternatively, once the MA PDU Session is established and user plane resources are allocated, after some period of time, the user plane resources are taken down or deallocated but the MA PDU Session is still maintained on both UE side and network side. Later on, when traffic has to be sent or received, the corresponding user plane resources are once again allocated. 
     Public land mobile network (PLMN) operators also increasingly deploy wireless local area network (WLAN) hotspots, such as WIFI hotspots, to offload traffic and thereby alleviate the loading of radio resources allocation in cellular systems. Such hotspots facilitate non-3GPP (N3PP) access by UE. Given that radio resources of such hotspots are “plentiful” and almost “cost-free”, it is envisaged that when a UE, such as the UE  10 , connects to the network  30 , such as 5G core (5GC) network, through such N3PP access, the user plane once being setup/established is available until the hotspot is “OFF” or the UE gets out of coverage of the hotspot. Then such user plane resources over N3GPP access will be unavailable. 
     Thus, when connected to a hotspot, such as the hotspot device  200   b , the UE  10  shall attempt to register to the PLMN, such as the network  30 , through the N3GPP access, such as the N3GPP access  20   b . Once the UE  10  is registered, the user plane resources are allocated and always available to the UE  10 . When the UE  10  can establish a lower layer connection to the N3GPP access network  20   b , the UE  10  shall attempt to get connected to the PLMN. Once successfully completing the attempt, the state of the UE  10  moves from IDLE to CONNECTED. When identifying that the UE is CONNECTED, the network  30  determines that user plane is available to the UE  10 . When determining that UE is not CONNECTED, the network  30  determines that the UE  10  cannot access the hotspot for whatever reason. 
     For a MA PDU Session, each of policy rules, known as ATSSS rules, indicates association between certain traffic or QoS flows and an access network. When DL data for a UE, such as the UE  10 , arrives at the network  30  with an ATSSS rule for that UE  10  indicating that kind of data or a QoS flow is allocated with 3GPP access, a network entity in the network  30 , such as the UPF  35 , delivers that DL data to the UE  10  through the user plane of a 3GPP access network  20   a . If the data plane is not available for the 3GPP access  20   a , a paging procedure is triggered to allow the UE  10  to respond over 3GPP access  20   a , set up a connection over 3GPP access  20   a , get the user plane resources of 3GPP access allocated for delivery of DL data. Then the DL data is delivered through the allocated user plane resources. The network  30  may include 5GC which includes UPF, SMF, AMF, unified data management (UDM), policy control function (PCF), control plane (CP)/user plane (UP) separation (CUPS), authentication server (AUSF), network slice selection function (NSSF), and the network exposure function (NEF). 
     In some embodiments, the processor  11  is configured to execute a method for allowing the UE  10  to respond cellular network signalling over a non-cellular radio access network includes the following steps: initiating a service request procedure over the non-cellular radio access for a cellular network service; receiving a service reject message in response to the service request procedure; entering an inactive state of the UE  10  over a non-cellular radio access; receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE  10 ; responding to the indication over the non-cellular radio access by initiating another service request procedure that activates the non-cellular radio access; entering an active state of the UE  10  over the non-cellular radio access upon activation of the non-cellular radio access which includes a connection and user plane; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE  10 . 
     In some embodiments, the processor  11  is configured to execute a method for allowing the UE  10  to respond cellular network signalling over a non-cellular radio access network includes the following steps: receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE  10  during an inactive state of the UE  10  over a non-cellular radio access; responding to the indication over the non-cellular radio access by initiating a service request procedure that activates the non-cellular radio access; entering an active state of the UE  10  over the non-cellular radio access upon activation of the non-cellular radio access which includes a connection and user plane; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE  10 . 
     In some embodiments, the cellular network signalling comprises Third Generation Partnership Project (3GPP) network signalling which is sent over a 3GPP access network. The non-cellular radio access connection comprises a non-3GPP radio access connection, such as wireless local area network (WLAN) connection. 
     In some embodiments, the indication comprises a paging message or a notification message. 
     In some embodiments, the inactive state of the UE  10  includes an IDLE non-access stratum (NAS) state. The active state of the UE  10  includes a CONNECTED NAS state. The method further comprises reactivating user plane resources of the non-cellular radio access for connection of the non-cellular radio access and the set of downlink data. 
     In some embodiments, an N1 NAS signalling connection of the UE  10  is released before the receiving of the indication. 
     In some embodiments, an N1 NAS signalling connection of the UE  10  is not released before the receiving of the indication. 
     In some embodiments, the method further includes: starting a backoff timer indicated by the service reject message after receiving the service reject message, wherein the backoff timer indicates a duration of time; refraining from requesting network service over the access where the service reject was received during the duration of time; and stopping the backoff timer and performing the initiating of the service request procedure that activates/reactivates the non-cellular radio access in response to receiving of the indication. 
     In some embodiments, the processor  11  is configured to execute a method for allowing the UE  10  to respond cellular network signalling over a non-cellular radio access network includes the following steps: initiating a service request procedure over non-cellular radio access for a cellular network service; receiving a service reject message in response to the service request procedure; keeping an active state of the UE  10  over a non-cellular radio access after receiving the service reject message; receiving an indication through cellular network signalling indicating that a set of downlink data for the non-cellular radio access are available for transmission to the UE  10  during the active state of the UE  10  over a non-cellular radio access; and receiving the set of downlink data through the user plane of the non-cellular radio access in the active state of the UE  10  in response to the indication. 
     In some embodiments, the method further includes: receiving a service reject message in response to an initial service request procedure initiated by the apparatus; starting a backoff timer indicated by the service reject message after receiving the service reject message, wherein the backoff timer indicates a duration of time; refraining from requesting network service over the access where the service reject was received during the duration of time; and stopping the backoff timer and performing the receiving of the set of downlink data in response to receiving of the indication. 
     When in the decision that DL data is to be delivered to the UE  10  over N3GPP access  20   b , the UPF  35  will push the UL data through the user plane over N3GPP access  20   b  if that user plane is available to the UE  10 , that is, if the UE  10  is CONNECTED. 
     However, if the UPF  35  find that the UE  10  is not connected over N3GPP access  20   b , that is if UE  10  is IDLE over N3GPP access  20   b , the network  30  will seek to deliver the DL data through 3GPP access  20   a  either through NOTIFICATION Procedure if UE  10  is CONNECTED over 3GPP access  20   a , or through Paging procedure if UE  10  is IDLE over 3GPP access  20   a . If the UE is IDLE over N3GPP access  20   b , the network determines that N3GPP access is unavailable to the UE  10 , and consequently delivers the DL data over 3GPP access  20   a  to the UE. The determination, however, is not always true. As demonstrated herewith, the UE  10  over N3GPP access  20   b  can stay in IDLE even though N3GPP access is available. Such event(s) or scenario(s) of not delivering the DL data over the intended N3GPP access breaks the ATSSS rule for that traffic or QoS flow as the 5G system loses the benefits of traffic offload to N3GPP access. What&#39;s more, how the DL data intended for N3GPP access  20   b  being delivered over 3GPP access  20   a  instead may exacerbate the stringent demands of scarce and precious radio resources of 3GPP cellular system. 
     Some scenarios that UE  10  over N3GPP access  20   b  is in IDLE while N3GPP access  20   b  is available to the UE is provided in the following: 
     As shown in  FIG. 3 , UE  10  in IDLE requests resources by performing a Service Request procedure ( 401 ), which starts with the UE  10  sending to the network a SERVICE REQUEST message  501  to the network  30 , such as the AMF  31 . Once accepting the request and allocates resources, the network  30 , such as the AMF  31 , returns to the UE a SERVICE ACCEPT  502  message ( 402 ). 
     As shown in  FIG. 4 , the UE  10  in IDLE sends to the network  30 , such as the AMF  31 , the SERVICE REQUEST message  501  to the network ( 401 ). If the network  30  is congested or determines not to provide resources to the UE  10 , the network  30  can reject the request with a SERVICE REJECT message  503  and provide a reason shown as “cause #22 (congestion)” for the rejection ( 403 ). The network  30  can also provide a backoff timer that indicates a duration of time during which the UE  10  is not allowed to access or request resources from the network  30 . 
     When the UE  10  receives the SERVICE REJECT  503  indicating that the network  30  is congested and a backoff timer is provided, the UE  10  performs or facilitates the following operations:
         triggered by the network  30 , releasing the N1 non-access stratum (NAS) signalling connection between the UE  10  and the network  30 ;   making the NAS  16  on UE side return to 5GMM_IDLE;   triggering the NAS  16  to run the backoff timer; and   keeping the NAS  16  from accessing network  30  for services until the backoff timer expires. The above steps are in compliance with TS 24.501.       

     Another series of events that can also lead to the scenario where the UE  10  is IDLE in N3GPP while N3GPP access is available are as follows:
         UE is ON with both cellular and WIFI radio functions active, that is not in-flight mode, and with SIM(s) enabled and mobile data set “ON”.   UE completes registration to PLMN via 3GPP access and also registers to PLMN via N3GPP access.   User manipulates the settings and either sets the WIFI “OFF” or modifies local configuration to turn off WIFI after detecting WIFI traffic of the UE is inactive for a period of time, such as 1 minute. For example, after detecting inactive WIFI traffic having been lasting for 1 minute, the UE  10  switches off WIFI function, and NAS in the UE  10  over N3GPP goes to IDLE.
 
As illustrated, many events may cause the UE  10  over N3GPP to be in IDLE while N3GPP access such as WIFI is still available.
       

     The disclosed method allows to complete DL data delivery to the UE through N3GPP access, thus abiding to ATSSS rules for data sessions of the UE. An ATSSS rule indicates certain traffic types or/and certain QoS flows to use certain radio access. 
     In general, the disclosed method allows a UE, such as the UE  10 , when paged or notified over 3GPP access  20   a  that DL data is to be transmitted to the UE through the N3GPP access  20   b , to re-establish the N3GPP connection from the UE to the network, re-activate 3GPP or N3GPP user plane and complete the data delivery through N3GPP access. 
     With reference to  FIG. 5 , in an embodiment of the method, the network  30  does not release the N1 NAS signalling connection with the UE  10  ( 405 ) after sending SERVICE REJECT message  503  with backoff timer to the UE  10 . Thus, the UE  10  and network  30  are kept in CONNECTED. The network  30  does not run an access network (AN) release procedure. 
     The UE  10  may run the backoff timer ( 404 ). The UE  10  thus does not make access attempts over N3GPP access  20   b  until the backoff timer expires. If paging or notification  504  arrives at the UE  10  ( 406 ) indicating that the network  30  has DL data for the UE  10  over the N3GPP access, the UE  10  stops the backoff timer ( 407 ) and responds to the indication from the network  30  over N3GPP access  20   b  ( 408 ) to complete the delivery of the DL data  506  over N3GPP access  20   b  ( 409 ). The indication of DL data  506  for the N3GPP access  20   b  by the paging or notification can reuse the existing Access Type with value “non-3GPP access” or can use a new value that can be recognized and determined by the UE  10  that the network  30  has DL data for the UE  10  over N3GPP access  20   b . The UE  10  can respond to the indication  504  by reactivating the N3GPP user plane resources for such data. More specifically, when receiving the indication, the UE  10  performs the service request procedure to get the non-3GPP user plane reactivated by the non-3GPP access  20   b  and the network  30 . 
     With reference to  FIG. 6 , in an alternative embodiment of the method, when N1 NAS signalling connection is released ( 415 ), the network  30  treats the UE  10  as IDLE, and reflects the IDLE state of the UE  10  in its UE related context of the UE. The UE  10  runs the backoff timer for N3GPP access ( 414 ). When the network  30  sends paging or notification  504  to the UE  10  over the 3GPP access  20   a  indicating that the network  30  has DL data for the UE  10  over N3GPP access ( 416 ), N3GPP NAS of the UE  10  stops the backoff timer ( 417 ), responds to the indication to facilitate delivery of the DL data over N3GPP access  20   b  to the UE  10 , and receives the DL data over N3GPP access  20   b . More specifically, when receiving the indication  504 , the UE  10  sends a SERVICE REQUEST  505  to the network  30  to perform the service request procedure ( 418 ), and thus to get the non-3GPP user plane reactivated by the non-3GPP access  20   b  and the network  30 . The UE  10  returns to CONNECTED over N3GPP access  20   b  after the service request procedure ( 419 ). The network  30  treats the UE  10  as CONNECTED, and reflects the CONNECTED state of the UE  10  in UE related context of the UE  10 . The network  30  sends the DL data  506  over N3GPP access  20   b  to the UE  10  ( 420 ) 
     With reference to  FIG. 7 , in another alternative embodiment of the method, when N1 NAS signalling connection is released ( 415 ), the network  30  treats the UE  10  as IDLE, and reflects the IDLE state of the UE  10  in its UE related context of the UE  10 . The UE  10  runs backoff timer for N3GPP access ( 414 ). If the network  30  sends paging or notification  507  to the UE  10  over the 3GPP access  20   a  ( 426 ) indicating “non-3GPP” while N3GPP access  20   b  represented by the “non-3GPP” is not available to the UE  10 , the UE  10  responds to the paging or notification through 3GPP access ( 427 ), and the network  30  delivers DL data  509  through 3GPP access ( 428 ). The UE  10  stops backoff timer ( 429 ), and starts necessary procedure to return to CONNECTED over N3GPP access  20   b . More specifically, when receiving the indication  507 , the UE  10  sends a SERVICE REQUEST  510  to the network  30  to perform the service request procedure ( 430 ), and thus to get the non-3GPP user plane reactivated by the non-3GPP access  20   b  and the network  30 . The UE  10  returns to CONNECTED over N3GPP access  20   b  after the service request procedure ( 431 ). The embodiment of the method enables the UE to be treated by the network  30  as active and connected in N3GPP access  20   b , in which N3GPP user plane resources are reactivated as available to the UE  10 . The network  30  can send further DL data  511  associated with N3GPP access as indicated by an ATSSS rule to the UE  10  through N3GPP access  20   b  associated with the DL data  511  ( 432 ). 
     With reference to  FIG. 8 , in still another embodiment of the method, the UE  10  requests for service by sending a SERVICE REQUEST  501  to the network  30  over the N3GPP access  20   b  ( 401 ). The network even when unable to grant the request due to network congestion or other reasons, sends a SERVICE REJECT  512  to the UE  10 , but does not instruct the UE  10  to perform backoff ( 433 ). The UE  10  are thus kept in CONNECTED over N3GPP access ( 434 ). That is, the network  30  keeps activation of user plane resources of the N3GPP access  20   b  for downlink data transmission to the UE  10  through a connection of the N3GPP access  20   b . Any DL data intended by an ATSSS rule to be sent over the N3GPP access will then get delivered over the intended access. More specifically, the network  30  sends the DL data  513  over N3GPP access  20   b  to the UE  10  ( 436 ) 
     Alternative embodiments and variations may be applied to cases where network rejects the UE while allowing delivery of DL data to UE over the access network intended by ATSSS rules, user settings, and/or local UE configurations. Furthermore, the disclosed methods, while being illustrated with MA PDU Sessions and the ATSSS feature, can applied to UE capable of using at least two heterogeneous wireless communication access interfaces, such as telecommunication and wireless LAN interfaces for which data delivery can be governed by other policies and rules other than ATSSS rules. 
     The disclosed method allows the UE  10  to get data delivered over the access network associated with the data as indicated by an ATSSS rule. When the UE  10  is seen as IDLE over the intended access but can actually get connected over that intended access, the UE  10  makes itself available to the network  30 , and the policy rules or user settings or UE local configurations can be followed. 
       FIG. 11  is a block diagram of an example system  700  for wireless communication according to an embodiment of the present disclosure. 
     Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software.  FIG. 11  illustrates the system  700  including a radio frequency (RF) circuitry  710 , a baseband circuitry  720 , an application circuitry  730 , a memory/storage  740 , a display  750 , a camera  760 , a sensor  770 , and an input/output (I/O) interface  780 , coupled with each other at least as illustrated. 
     The application circuitry  730  may include a circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system. 
     The baseband circuitry  720  may include a circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. 
     In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. 
     For example, in some embodiments, the baseband circuitry may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). 
     Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. 
     In various embodiments, the baseband circuitry  720  may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. 
     For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency. 
     The RF circuitry  710  may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. 
     In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. 
     In various embodiments, the RF circuitry  710  may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. 
     For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency. 
     In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the user equipment, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitries, the baseband circuitry, and/or the application circuitry. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or a memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. 
     In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. 
     In some embodiments, some or all of the constituent components of the baseband circuitry, the application circuitry, and/or the memory/storage may be implemented together on a system on a chip (SOC). 
     The memory/storage  740  may be used to load and store data and/or instructions, for example, for system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM)), and/or non-volatile memory, such as flash memory. 
     In various embodiments, the I/O interface  780  may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface. 
     In various embodiments, the sensor  770  may include one or more sensing devices to determine environmental conditions and/or location information related to the system. 
     In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. 
     In various embodiments, the display  750  may include a display, such as a liquid crystal display and a touch screen display. 
     In various embodiments, the system  700  may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. 
     In various embodiments, system may have more or less components, and/or different architectures. Where appropriate, methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium. 
     The embodiment of the present disclosure is a combination of techniques/processes that can be adopted in 3GPP specification to create an end product. 
     A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed. 
     It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized with other ways. 
     The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated in another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms. 
     The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. 
     Moreover, each of the functional units in each of the embodiments can be integrated in one processing unit, physically independent, or integrated in one processing unit with two or more than two units. 
     If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk, or other kinds of media capable of storing program codes. 
     The disclosed method provides efficient use of resources, which helps in meeting costs targets, and expected service performance and policies. Especially given that the N3GPP access is the choice of radio access networks to offload data traffic from the cellular network is desired by many PLMN operators. The disclosed method supports to offload traffic through N3GPP access. 
     While the present disclosure has been described in connection with certain embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.