Patent Description:
This background description is provided for the purpose of generally presenting the context of the disclosure.

A device which an end user can use to communicate via a mobile network, usually referred to as "user equipment" (UE), in some cases is capable of communicating with more than one mobile network. For example, the UE can include more than one identity specific to a certain network provider, and can use these identities to connect to different mobile networks as a respective subscriber.

For example, the UE can include more than one Universal Subscriber Identity Module (USIM), which is a software module that executes on a Universal Integrated Circuit Card (UICC) to provide security and authentication functionality, or more than one embedded SIM (e-SIM). In any case, hardware and/or software components can provide multiple subscriber identities. Using one of these subscriber identities, the UE can connect to a certain mobile network such as a Public Land Mobile Network (PLMN) and utilize some or all of the services of the PLMN (e.g., voice calling, video calling, web browsing). The UE then connects to another PLMN or the same PLMN using another subscriber identity, without the user powering down or resetting the UE, let alone replacing any part of the hardware such as a physical card. Nevertheless, the UE may not be able to exchange user-plane data with both PLMNs at the same time.

Today, it is not clear how a PLMN should treat data addressed to the UE when the UE temporarily transitions to another PLMN. For example, a UE equipped with respective USIMs for PLMN<NUM> and PLMN<NUM> may at some point receive a paging request from PLMN<NUM> while receiving data service from PLMN<NUM>. The UE may transition to PLMN<NUM> at least temporarily while PLMN<NUM> continues receiving downlink data for delivery to the UE via a radio interface. <CIT> Al forms part of the related prior art.

Generally speaking, a UE of this disclosure has multiple subscriber identities for communicating with multiple respective mobile networks, or the same mobile network according to different subscriptions. The device determines its preference regarding how a mobile network should process downlink data addressed to the device when the device transitions from the current subscription to another subscription.

One example embodiment of these techniques is a method in a UE having a first subscriber identity module for connecting to a first mobile network according to a first subscription and a second subscriber identity module for connecting to the first mobile network or a second mobile network according to a second subscription. The method can be implemented by processing hardware such as one or more processors executing instructions stored on a non-transitory computer readable medium and includes determining a preference of how the first mobile network is to process downlink data for the UE when the UE transitions from the first subscription to the second subscription; and transmitting, to the first mobile network, an indication of the preference, to cause the first mobile network to process the downlink data for the UE based at least in part on the preference.

Another example embodiment of these techniques is a UE including processing hardware and configured to implement the method above.

Still another example embodiment of these techniques is a method in a first mobile network for processing downlink data for a UE having a first subscriber identity module for connecting to the first mobile network according to a first subscription and a second subscriber identity module for connecting to the first mobile network or a second mobile network according to a second subscription. The method can be implemented by processing hardware such as one or more processors executing instructions stored on a non-transitory computer readable medium and includes receiving, from the UE, an indication of how the UE prefers the first mobile network to process downlink data for the UE when the UE transitions from the first subscription to the second subscription; detecting that the UE has transitioned from the first subscription to the second subscription; and processing downlink data for the UE based at least part on the indication.

Yet another example embodiment of these techniques is a base station including processing hardware and configured to implement one of the methods above.

In the following, <FIG> and <FIG> and their description include the claimed invention. The remaining description does not or does not fully correspond to the claimed invention but is useful for understanding the invention. <FIG> illustrates an example wireless communication system <NUM> in which a UE <NUM> is a multi-USIM device that implements the techniques of this disclosure. The UE <NUM> communicates with a base station <NUM>, which operates in a radio access network (RAN) <NUM> coupled to a core network (CN) 120A, as well as with the base station <NUM>, which operates in a RAN <NUM> coupled to a CN 120B. The RAN <NUM> and the core network 120A are associated with PLMN<NUM>, and the RAN <NUM> and the CN 120B are associated with PLMN<NUM>.

As discussed in more detail below, the UE <NUM> determines its preference with respect to downlink data which a mobile network such as PLMN<NUM> may receive for the UE <NUM> when the UE <NUM> has at least temporarily transitioned to another mobile network such as PLMN<NUM> or to another subscription on PLMN<NUM> The preference can be, for example, for the mobile network to buffer pending downlink data, discard pending downlink data, buffer newly arriving downlink data, and/or discard newly arriving downlink data. The UE <NUM> can determine the preference and indicate the preference to the mobile network, which in turn may process downlink data for the UE in accordance with the preference, unless the preference conflicts with one or more policies of the mobile network.

For clarity, the examples below refer primarily to the UE transitioning between a subscription on PLMN<NUM> and a subscription PLMN<NUM>. These techniques however also apply to the UE transitioning between subscriptions on the same PLMN, unless otherwise stated.

The UE <NUM> can determine this preference dynamically and/or statically. For example, the UE can determine its preference upon receiving a paging request from a new (second) mobile network, and base the determination on the type of data the UE <NUM> is currently receiving from the first mobile network, and/or how long the UE <NUM> expects to communicate with the second mobile network (which in turn may depend on what kind of service the UE expects to use with the second mobile network). Additionally or alternatively, the UE <NUM> can store persistent settings, which may be user-specific or manufacturer-specific for example.

Further, the UE <NUM> can specify its preference at various levels of granularity, e.g., for all downlink data, for downlink data associated with a particular PDU session or PDN connection, or for downlink data associated with a particular QoS flow or EPS bearer. The UE <NUM> can provide the reference to the mobile network using Non-Access Stratum (NAS) messaging or Radio Resource Control (RRC) messaging, depending on the implementation and/or scenario.

As illustrated in <FIG>, the base station <NUM> supports a cell <NUM>, and the base station <NUM> supports a cell <NUM>. The cells <NUM> and <NUM> can partially overlap, so the UE <NUM> can receive for example a paging request from PLMN<NUM> in the cell <NUM> while communicating with PLMN<NUM> in the cell <NUM>. Generally, the wireless communication system <NUM> may include any suitable number of base stations supporting NR cells and/or EUTRA cells. More particularly, the CNs 120A and 120B can be connected to any suitable number of base stations supporting cells.

The CN 120A may be an evolved packet core (EPC) <NUM> or a fifth-generation core (5GC) <NUM>, both of which are depicted in <FIG>. The CN 120B similarly can be implemented as an EPC, a 5GC, or another suitable core network. Each of the base stations <NUM> and <NUM> may be an eNB supporting an S1 interface for communicating with the corresponding EPC, an ng-eNB supporting an NG interface for communicating with the corresponding 5GC, or a gNB that supports the NR radio interface as well as an NG interface for communicating with the 5GC. The base station <NUM> may be an EUTRA-NR DC (EN-DC) gNB (en-gNB) with an S1 interface to the EPC <NUM>, an en-gNB connected to the EPC <NUM>, a gNB that supports the NR radio interface as well as an NG interface to the 5GC <NUM>, or an ng-eNB that supports an EUTRA radio interface as well as an NG interface to the 5GC <NUM>.

Among other components, the EPC <NUM> can include a Mobility Management Entity (MME) <NUM>, a Serving Gateway (SGW) <NUM>, and a Packet Data Network Gateway (PGW) <NUM>. The MME <NUM> is generally configured to manage authentication, registration, paging, and other related functions. The SGW <NUM> is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc. The PGW <NUM> is generally configured to provide connectivity from the UE <NUM> to one or more external packet data networks, e.g., an Internet network <NUM> and/or an Internet Protocol (IP) Multimedia Subsystem (IMS) network.

The 5GC <NUM> includes Mobility Management Function (AMF) <NUM>, an Session Management Function (SMF) <NUM>, and a User Plane Function (UPF) <NUM>. The AMF <NUM> is generally configured to manage authentication, registration, paging, and other related functions; the SMF <NUM> is generally configured to manage Protocol Data Unit (PDU) sessions, and the UPF <NUM> is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc..

Each of the components <NUM>-<NUM> and <NUM>-<NUM> can be implemented in processing hardware that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units.

Although the examples below refer specifically to specific CN types (EPC, 5GC) and specific radio access technology (RAT) types (<NUM> NR and EUTRA), in general the techniques of this disclosure can also apply to other suitable radio access and/or core network technologies, such as sixth generation (<NUM>) radio access, and/or <NUM> core network or <NUM> NR-<NUM> DC, for example.

With continued reference to <FIG>, the CN 120A can implement a downlink (DL) data controller <NUM>. For example, the DL data controller <NUM> can be implemented in the SGW <NUM> when the CN 120A is implemented as an EPC, or the UPF <NUM> when the CN 120A is implemented as a 5GC. As another example, the DL data controller <NUM> can be implemented partially in the SMF <NUM> and partially in the UPF <NUM>. Moreover, the DL data controller <NUM> in some implementations is partially implemented in the base station <NUM>. The DL controller <NUM> more generally can be implemented in one or more components of the CN 120A and/or the RAN <NUM>.

In operation, the DL data controller <NUM> determines the preference of the UE <NUM> with respect to processing downlink data when the UE <NUM> temporarily or permanently leaves the PLMN<NUM>, in some implementations also determines the relevant policy of the CN 120A, and applies the preference and/or policy in relevant scenarios. Some of the scenarios are discussed below with reference to <FIG>.

Still referring to <FIG>, the UE <NUM> is equipped with processing hardware <NUM> that can include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. The UE <NUM> also includes USIM<NUM> (component <NUM>) and USIM<NUM> (component <NUM>) for communicating with PLMN<NUM> and PLMN<NUM>, respectively. In some implementations, however, the UE <NUM> uses USIM<NUM> as well as USIM<NUM> to communicate with the same mobile network, such PLMN<NUM> or PLMN<NUM>, according to different subscriber identities. Either USIM may be associated with a card as a part of a UICC (commonly called a "SIM card") or may be embedded as an eSIM.

The processing hardware <NUM> in an example implementation includes a DL data controller <NUM> configured to support the techniques of this disclosure for managing downlink data at the PLMN<NUM>. In operation, the DL data controller <NUM> can determine persistent settings <NUM> stored in the memory of the UE <NUM> (e.g., manufacturer settings, operator settings, user settings) and/or the dynamic conditions associated with the applications and services <NUM> (APP<NUM>, APP<NUM>,. APPN), such as voice and video call services, SMS services, web browsing applications, mailing applications, gaming applications, or music streaming applications, for example.

Next, <FIG> illustrates in a simplified manner a radio protocol stack according to which the UE <NUM> can communicate with an eNB/ng-eNB or a gNB. Each of the base stations <NUM>, <NUM> can be the eNB/ng-eNB or the gNB.

The physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA Medium Access Control (MAC) sublayer 204A, which in turn provides logical channels to the EUTRA Radio Link Control (RLC) sublayer 206A, and the EUTRA RLC sublayer in turn provides RLC channels to the EUTRA PDCP sublayer <NUM> and, in some cases, NR PDCP sublayer <NUM>. Similarly, the PHY 202B of NR provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B, and the NR RLC sublayer 206B in turn provides RLC channels to the NR PDCP sublayer <NUM>. The UE <NUM> in some implementations supports both the EUTRA and the NR stack, to support handover between EUTRA and NR base stations and/or DC over EUTRA and NR interfaces. Further, as illustrated in Fig. 2A, the UE <NUM> can support layering of NR PDCP <NUM> over EUTRA RLC 206A.

The EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> receive packets (e.g., from the Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer <NUM> or <NUM>) that can be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer 206A or 206B) that can be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure for simplicity refers to both SDUs and PDUs as "packets.

On a control plane, the EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> provide SRBs to exchange Radio Resource Control (RRC) messages, for example. On a user plane, the EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> provide DRBs to support data exchange.

When the UE <NUM> operates in EUTRA/NR DC (EN-DC), with the BS <NUM> operating as a MeNB and the BS <NUM> operating as a SgNB, the network can provide the UE <NUM> with an MN-terminated bearer that uses EUTRA PDCP <NUM> or MN-terminated bearer that uses NR PDCP <NUM>. The network in various scenarios also can provide the UE <NUM> with an SN-terminated bearer, which use only NR PDCP <NUM>. The MN-terminated bearer can be an MCG bearer or a split bearer. The SN-terminated bearer can be a SCG bearer or a split bearer. The MN-terminated bearer can be an SRB (e.g., SRB1 or SRB2) or a DRB. The SN-terminated bearer can an SRB (e.g., SRB) or a DRB.

Next, several scenarios in which a mobile network processes downlink data based at least in part on a preference of a UE are discussed with reference to <FIG>. Although the signaling diagrams of <FIG> show two core networks 120A, 120B and assume different PLMNs, the techniques shown also apply to the UE transitioning between different subscriptions on the same PLMN, unless otherwise stated.

Referring first to <FIG>, the UE <NUM> in a scenario <NUM> optionally provides <NUM> an indication of the default preference regarding processing downlink data to the CN 120A. The default preference can apply to situations in which the UE <NUM> leaves the PLMN<NUM> temporarily (e.g. for an amount of time less than TMAX) or permanently (e.g. for an amount of time greater than TMAX). The preference can apply to downlink data that is already pending at the time when the UE <NUM> notifies the PLMN<NUM> of leaving, to downlink data that arrives after the UE <NUM> has notified the PLMN<NUM> of leaving but before the expiration of time interval TMAX, or both. The value of TMAX can be for example <NUM>. <NUM>, <NUM>, <NUM> secs, or any other value, and can depend on the PLMN, the manufacturer of the UE <NUM>, application servers in communication with the UE, or the relevant 3GPP standard, for example.

In some cases, the CN 120A specifies the value of TMAX to the UE <NUM> using a NAS message. If the UE <NUM> fails to return to the CN 120A within the predetermined time period TMAX, the CN <NUM> flushes the stored downlink data as will be described later.

For example, the default preference can be a tuple {buffer, buffer}, {buffer, discard}, {discard, buffer}, or {discard, discard} specifying the default actions for the pending downlink data and the newly arriving downlink data, respectively. In some implementations, the default preference for pending and/or newly arriving data can be set to "do not care" to effectively allow the CN 120A apply its default policy. As another example, the default preference can be "return," indicating that the UE <NUM> intends to return to PLMN<NUM> to resume an ongoing data transfer (e.g., a PDU session) which an event such as paging request from PLMN<NUM> interrupts, or "not return," indicating that the UE <NUM> does not intend or expect to return to PLMN<NUM> after transitioning to PLMN<NUM>. In this case, the CN 120A can apply the default policy for this preference, e.g., {buffer, buffer} for "return" or {discard, discard} for "not return.

The UE <NUM> in some implementations can further parameterize the default preference by specifying the maximum amount of data to buffer, for example. Thus, the UE <NUM> can format the default preference as {buffer X, buffer Y}, to request that the PLMN<NUM> buffer up to X bytes of pending downlink data and up to Y bytes of newly arriving downlink data. The CN 120A similarly can apply, when appropriate, a policy that limits the amount of buffered pending downlink data and/or newly arriving downlink data.

In some implementations, the CN 120A is configured to receive, from the UE <NUM> or from the CN 120B, an indication of the service in connection with which the CN 120B pages the UE <NUM> when the UE <NUM> is communicating with the CN 120A. The CN 120A can determine for example whether the UE <NUM> received from the CN 120B a paging request for SMS delivery or a paging request for a voice call. When the UE <NUM> transitions from one subscription to another subscription on the same PLMN, the CN 120A also can identify the service to the which the paging request associated with the new subscription relates. In these cases, the default preference can be service-specific, e.g., { {SMS: buffer, buffer}, {MMS call: buffer, discard}, {Voice call: discard, discard},. Alternatively, the UE <NUM> can specify the preference in terms of the intent associated with a particular service: {{SMS: return}, {MMS call: return}, {Voice call: not return},.

Still further, the default preference in various implementations specifies how the UE <NUM> would like the CN 120A to process downlink data at various levels of granularity. For example, the UE <NUM> can specify the preference for a certain Quality of Service (QoS) or an EPS bearer.

In some implementations, the UE <NUM> provides <NUM> the default notification to the MME <NUM> or the AMF <NUM> during registration using the Mobility Management (MM) protocol. The UE <NUM> can include an information element (IE) in one of the uplink messages. In another implementation, the UE <NUM> provides <NUM> the default notification to the CN 120A only when the UE <NUM> expects to establish a PDN session or a PDU session using the Session Management (SM) protocol. The UE <NUM> in some implementations also can provide <NUM> the default notification in response to the user changing certain settings. In those implementations or scenarios where the UE <NUM> does not provide a default preference at all, the CN 120A can apply a default policy. In general, the UE <NUM> can provide the default notification to the CN 120A zero times, once, or multiple times while active in PLMN<NUM>.

With continued reference to <FIG>, the UE <NUM> can receive <NUM> downlink data packets in a communication session with the CN 120A. For example, the UE <NUM> can receive data packets of a certain PDU session which a music playback application <NUM> established to stream music.

While the UE <NUM> continues to receive <NUM> downlink data, the CN 120B transmits a paging request to the UE <NUM>. In some implementations, the paging information includes a service indicator to indicate whether the CN 120B is paging the UE <NUM> in connection with SMS delivery, MMS delivery, a mobile-terminated voice call, a mobile-terminated video call, etc. In other implementations, the UE <NUM> cannot determine the type of service when receiving <NUM> the paging information. The UE <NUM> in some of these cases can determine the type of service at a later time, based on subsequent messaging with the CN 120B. Further, in some cases it is possible for PLMN<NUM> provide an indication of the service of the paging request directly to PLMN<NUM>.

In response to receiving <NUM> the paging request, the UE <NUM> determines whether the UE <NUM> intends (or plans) to return to the CN 120A upon completing the service to which the paging request from the CN 120B relates. As discussed below, the UE <NUM> may not always determine the intent correctly, and in some cases may re-assess the intent at a later time.

In the scenario of <FIG>, the UE <NUM> determines <NUM> that the UE <NUM> intends to return to the CN 120A after receiving the information to which the paging request relates. For example, the UE <NUM> can determine that the paging request relates to SMS or MMS delivery, and that receiving downlink data from the CN 120B can complete within the predetermined time period TMAX. The UE <NUM> transmits <NUM> an indication of the downlink data processing preference to the CN 120A, to specify the preference of buffering pending downlink data as well as newly arriving pending downlink data. The indication of the event <NUM> can override the default preference of the event <NUM>.

Similar to the default preference discussed in connection with the event <NUM>, the UE <NUM> can transmit <NUM> the preference to the AMF <NUM> using a NAS message, the AMF <NUM> can forward the preference to the SMF <NUM>, and the SMF <NUM> can turn can configure the UPF <NUM> in accordance with the preference. Alternatively, if the CN 120A is implemented as an EPC, the UE <NUM> can transmit a NAS message including an indication of the downlink processing preference to the MME <NUM>, which can provide the preference to the SGW <NUM>. As an alternative to NAS message, the UE <NUM> can use an RRC message, in both E-UTRAN and NG-RAN, to specify the preference to the RAN <NUM>. The base station <NUM> in this implementation can forward the preference to the AMF <NUM>.

The UE <NUM> can specify the preference for a particular QoS flow or an EPS bearer. The UE <NUM> additionally or alternatively can specify the preference for a particular PDU session or a PDN connection. For example, the procedure <NUM> can involve a PDU session S<NUM> of a web browser and a PDU session S<NUM> of a video streaming application. The UE <NUM> in this case can transmit <NUM> multiple PDU-session-specific preferences, e.g., { { S<NUM>: buffer, discard}, { S<NUM>: buffer, buffer}}. Also similar to the default preference discussed above, the UE <NUM> can specify buffer size limits for the pending downlink data and/or the newly arriving downlink data.

In some implementations, the UE <NUM> transmits <NUM> the preference to the CN 120A after establishing a service with the CN 120B. In other implementations, at the time of transmitting <NUM> the preference, the UE <NUM> cannot determine whether the service related to the paging request of the event <NUM> is SMS or voice call, but the CN 120A may be able to determine the type of service at a later time. The UE <NUM> in this scenario can specify respective preferences for the multiple services, e.g., { {SMS: buffer, buffer}, {voice call: discard, discard} }. The CN 120A can apply the appropriate preference upon determining for which service the UE <NUM> transitioned to the other mobile network.

In accordance with the specified preference, the CN 120A buffers <NUM> pending downlink data (i.e., the data the CN 120A had already received from a data source for the UE <NUM> by the time the CN 120A received <NUM> the preference). The CN 120A also buffers <NUM> newly arriving downlink data, in accordance with the preference.

Prior to buffering or discarding downlink data in accordance with the UE preference, the CN 120A in some implementations determines whether this preference conflicts with the relevant policy of the CN 120A. The policy can for example restrict the ability of UEs to buffer data at the CN due to memory restrictions. In some cases, the policy is UE-specific. When the CN 120A determines that the UE preference is incompatible with the CN policy, the CN 120A can determine that the CN policy takes precedence over the UE preference. The CN 120A in this case may inform the UE <NUM> what policy the CN 120A has applied, so that the UE <NUM> is aware of how the CN 120A will process downlink data. In some of these implementations, the CN 120A transmits an acknowledgement to the transmission <NUM>, with an indication whether the CN 120A accepted the preference of the UE <NUM> and, if the CN 120A has not fully accepted the preference, what kind of modifications to the preference the CN 120A has applied.

With continued to reference to <FIG>, the UE <NUM> communicates <NUM> with the CN 120B of the new mobile network, PLMN<NUM>. The UE <NUM> then reconnects <NUM> to the original mobile network, PLMN<NUM>. The CN 120A delivers <NUM> buffered downlink data, which in this case includes the data packets that were pending at the time of the event <NUM> as well as the data packets that arrived subsequent to the event <NUM>.

Next, several scenarios generally similar to the scenario <NUM> are discussed below with reference to <FIG>. Events in these procedure similar to those discussed above with respect to the procedure <NUM> are labeled with similar reference numbers (e.g., with event <NUM> of <FIG> or event <NUM> of <FIG> corresponding to event <NUM> of <FIG>). With the exception of the differences illustrated in <FIG> and the differences described below, any of the alternative implementations discussed above with respect to the procedure <NUM> (e.g., for messaging and processing) may apply to the procedures of <FIG>.

Referring to <FIG>, an example scenario <NUM> is similar to the scenario <NUM>, but here the UE <NUM> specifies a different preference for processing downlink data. The UE <NUM> in this scenario also determines <NUM> that the UE <NUM> intends to return to the CN 120A after receiving the information to which the paging request relates, within the predetermined time period TMAX, but the UE <NUM> transmits <NUM> a different indication of the downlink data processing preference to the CN 120A. The UE <NUM> in the scenario <NUM> specifies the preference of buffering pending downlink data but discarding newly arriving downlink data. The CN 120A buffers <NUM> the pending downlink data and discards <NUM> the newly arriving downlink data, in accordance the preference. After the UE <NUM> reconnects <NUM> to the CN 120A, the CN 120A delivers <NUM> the buffered downlink data, which in this case includes the data packets that were pending at the time of the event <NUM> but excludes the data packets that arrived subsequent to the event <NUM>.

Next, <FIG> illustrates an example scenario <NUM> also similar to the scenario <NUM>, but with the UE <NUM> specifying yet another preference for processing downlink data. The UE <NUM> in this scenario also determines <NUM> that the UE <NUM> intends to return to the CN 120A after receiving the information to which the paging request relates, within the predetermined time period TMAX, but the UE <NUM> transmits <NUM> a preference of discarding pending downlink data but buffering newly arriving downlink data. The CN 120A discards <NUM> the pending downlink data but buffers <NUM> the newly arriving downlink data, in accordance the preference. After the UE <NUM> reconnects <NUM> to the CN 120A, the CN 120A delivers <NUM> the buffered downlink data, which in this case excludes the data packets that were pending at the time of the event <NUM> but includes the data packets that arrived subsequent to the event <NUM>.

<FIG> illustrates an example scenario <NUM> also similar to the scenario <NUM>, but with the UE <NUM> specifying still another preference for processing downlink data. The UE <NUM> in this scenario also determines <NUM> that the UE <NUM> does not intend to return to the CN 120A after receiving the information to which the paging request relates within the predetermined time period TMAX. Alternatively, the UE <NUM> determines <NUM> intends to return to the CN 120A within the predetermined time period TMAX, but also determines that the downlink data received at the CN 120A prior to the UE's return should be discarded. The UE <NUM> transmits <NUM> a preference of discarding pending downlink data as well newly arriving downlink data. The CN 120A discards <NUM> the pending downlink data and discards <NUM> the newly arriving downlink data, in accordance the preference. After the UE <NUM> reconnects <NUM> to the CN 120A, the CN 120A need not deliver downlink data the UE <NUM> missed while communicating with the CN 120B.

Next, <FIG> illustrates an example scenario <NUM> also similar to the scenario <NUM>, but with the UE <NUM> specifying the preference in terms of the intent to return to the original mobile network after temporarily connecting to a new mobile network. The UE <NUM> determines <NUM> that the UE <NUM> intends to return to the CN 120A after receiving the information to which the paging request relates within the predetermined time period TMAX. The UE <NUM> transmits <NUM> a preference indication that specifies the intent of the UE to return to the CN 102A. The CN 120A then determines <NUM> the downlink data policy for the preference, based on applicable CN rules and/or settings specific to the UE <NUM>. The CN 120A buffers or discards <NUM> the pending downlink data and buffers or discards <NUM> the newly arriving downlink data, in accordance the preference of the event <NUM> and the determination of the event <NUM>. After the UE <NUM> reconnects <NUM> to the CN 120A, the CN 120A transmits <NUM> the buffered downlink data, when applicable.

<FIG> illustrates an example scenario <NUM> similar to the scenario <NUM>, but with the UE <NUM> updating its preference after specifying the initial preference to the original mobile network. The UE <NUM> determines <NUM> that the UE <NUM> intends to return to the CN 120A after receiving the information to which the paging request relates, within the predetermined time period TMAX. The UE <NUM> transmits <NUM> its initial preference P<NUM> to the CN 120A and activates a timer <NUM>, which can have the expiration time of TMAX or, in some scenarios, another expiration time. When the timer <NUM> expires, the UE <NUM> determines that the communication procedure <NUM> with the CN 120B is still ongoing. The UE <NUM> in response transmits an updated preference P<NUM> to the CN 120A. In some cases, the updated preference is the same as the original preference. In other cases, the UE <NUM> changes the preference due to the expected expiration of application-level timers, for example, which would cause the corresponding application to discard the buffered data in any case. As illustrated in <FIG>, the CN 120A buffers or discards <NUM> the pending downlink data and buffers or discards <NUM> the newly arriving downlink data in accordance the preference indicated in the event <NUM>, and then buffers or discards <NUM> the pending downlink data and buffers or discards <NUM> the newly arriving downlink data in accordance the preference indicated in the event <NUM>. If the CN 120A has its own buffer size limit for storing downlink data for a UE, the CN 120A may override the preferences received <NUM>, <NUM> when they exceed the CN 120A buffer size.

For clarity, <FIG> illustrates a message sequence diagram of a scenario <NUM> in which the UE notifies <NUM> the CN 120A of the downlink data processing preference of the UE <NUM> using a NAS message. Although the UE <NUM> communicates with the CN 120A only indirectly, via a radio interface between the UE <NUM> and the RAN <NUM> (e.g., the base station <NUM>), the RAN <NUM> in this scenario does not process the indication of downlink data processing preference and only forwards the preference to the CN 120A.

On the other hand, <FIG> illustrates a message sequence diagram of a scenario <NUM> in which the UE <NUM> transmits <NUM> an RRC message with an indication of the downlink data processing preference of the UE <NUM> to the RAN <NUM>. The base station <NUM>, or another node in the RAN <NUM>, processes the indication, formats an interface message including the indication (or another, differently formatted indication based on the indication received from the UE <NUM>), and transmits <NUM> the interface message to the CN 120A.

For additional clarity, example methods which the UE <NUM> and the CN 120A of <FIG> can implement to support downlink data processing preferences of this disclosure are discussed with reference to <FIG>, respectively. These methods can be implemented as software instructions stored on a computer-readable medium and executed by one or more processors, for example. Although these methods are discussed below with specific reference to the UE <NUM> and the CN 120A, these methods also can be implemented in other suitable devices.

Referring first to <FIG>, the UE <NUM> can implement an example method <NUM> to request that a mobile network process downlink data in view of a preference of the UE <NUM>, when the UE <NUM> transitions to another mobile network. At block <NUM>, the UE <NUM> determines a preference of how the mobile network should process downlink data for the UE <NUM>, for those situations where the UE <NUM> transitions to another mobile network (or the same mobile network according to a different subscription) only temporarily (see, e.g., event <NUM> in <FIG>, event <NUM> in <FIG>, event <NUM> in <FIG>, event <NUM> in <FIG>, event <NUM> in <FIG>, or event <NUM> in <FIG>).

At block <NUM>, the UE transmits an indication of the preference to the CN 120A of the original mobile network (see, e.g., event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> of <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM>, <NUM>, or <NUM> of <FIG>, event <NUM> of <FIG>, event <NUM> of <FIG>).

Finally, <FIG> illustrates a flow diagram <NUM> of an example method in a mobile network for processing downlink data for the UE <NUM>, when the UE <NUM> transitions to another mobile network or the same mobile network according to a different subscription. At block <NUM>, the mobile network receives an indication of a preference of how the mobile network should process downlink data for the UE <NUM>, for those situations where the UE <NUM> transitions to another mobile network only temporarily (see, e.g., event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> of <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM>, <NUM>, or <NUM> of <FIG>, event <NUM> of <FIG>, event <NUM> of <FIG>).

At block <NUM>, the mobile network determines that the UE <NUM> has transitioned to another mobile network. To avoid clutter, the events associated with notifying the CN 120A of the UE <NUM> temporarily leaving PLMN<NUM> are not shown separately, but in some implementations the UE <NUM> includes an indication of the preference regarding processing downlink data in a notification that the UE <NUM> is temporarily leaving PLMN<NUM> (see, e.g., event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> of <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM> or <NUM> of <FIG>, event <NUM>, <NUM>, or <NUM> of <FIG>, event <NUM> of <FIG>, event <NUM> of <FIG>).

At block <NUM>, the CN 120A processes downlink data for the UE <NUM> in view of the preference (see, e.g., events <NUM> and <NUM> of <FIG>, events <NUM> and <NUM> of <FIG>, events <NUM> and <NUM> of <FIG>, events <NUM> and <NUM> of <FIG>, events <NUM> and <NUM> of <FIG>, events <NUM>-<NUM> of <FIG>). As discussed above, the CN 120A may not always comply with the preference of the UE due to conflicts with the policy of the CN, restrictions of the UE, exceeding data limits, etc..

The following additional considerations apply to the foregoing discussion.

A user device or UE in which the techniques of this disclosure can be implemented (e.g., the UE <NUM>) can be any suitable device capable of wireless communications such as a smartphone, a tablet computer, a laptop computer, a mobile gaming console, a point-of-sale (POS) terminal, a health monitoring device, a drone, a camera, a media-streaming dongle or another personal media device, a wearable device such as a smartwatch, a wireless hotspot, a femtocell, or a broadband router. Further, the user device in some cases may be embedded in an electronic system such as the head unit of a vehicle or an advanced driver assistance system (ADAS). Still further, the user device can operate as an internet-of-things (IoT) device or a mobile-internet device (MID). Depending on the type, the user device can include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc..

Certain embodiments are described in this disclosure as including logic or a number of components or modules. Modules may can be software modules (e.g., code, or machine-readable instructions stored on non-transitory machine-readable medium) or hardware modules. A hardware module is a tangible unit capable of performing certain operations and may be configured or arranged in a certain manner. A hardware module can comprise dedicated circuitry or logic that is permanently configured (e.g., as a special-purpose processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

Claim 1:
A method in a user equipment, UE, having a first subscriber identity module for connecting to a first mobile network according to a first subscription and a second subscriber identity module for connecting to a second mobile network according to a second subscription, the method comprising:
transitioning from the first subscription to the second subscription; the method is characterized by
in view of the transitioning, transmitting (<NUM>), by the UE to the first mobile network, an indication of a preference of how the first mobile network should process downlink data for the UE, the indication including a certain value in response to determining that the UE intends to return to the first subscription within a predetermined period of time (<NUM>).