Techniques for performing network handover operations

Abstract

Methods, systems, and devices for wireless communication are described. A user equipment (UE) can identify (305) that the UE is not connected with a first network to which the UE is subscribed, and identify (310) a fallback configuration. The UE can determine (315) a second network of one or more other networks with which the UE is to connect based on the fallback configuration. The UE can attempt (320) to connect with the second network based on the fallback configuration and the UE not being connected with the first network. In some cases, a base station of a network can establish connections with UEs based on receiving registration messages from the UEs in response to transmitting an indication that the network is available as a fallback network, identify a congestion level of the network, and switch to a non-subscriber rejection mode in which the base station rejects connections with non-subscriber UEs.

Description

[0001] Cross-references

[0002] This patent application claims priority to Greek patent application No. 20200100667 entitled “TECHNIQUESFOR PERFORMING A NETWORK SWITCHING OPERATION”, filed on November 5, 2020, by Chaponniere et al., which has been assigned to the assignee of this application.

[0003] background

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, message sending and receiving, broadcasting, and so on. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth-generation (4G) systems (such as Long Term Evolution (LTE) systems, LTE-A Advanced (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems, which may be referred to as New Radio (NR) systems. These systems can employ various technologies, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Discrete Fourier Transform Extended Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each of which simultaneously supports communication from multiple communication devices, which may also be referred to as User Equipment (UE).

[0005] In some wireless communication systems, a UE can be a subscriber to a network. In some situations, the network may be unable to provide service to its subscribers. For example, a disaster may occur that renders the network unable to provide service in an area. In another example, the network may lack coverage in one or more areas. In such situations, network subscribers may roam to compete for service from another network to which the UE is not subscribed. Conventional techniques associated with UE network handover in such scenarios can be improved.

[0006] Overview

[0007] The described technology relates to improved methods, systems, devices, and apparatuses supporting techniques for performing network handover operations. Generally, the described technology provides enhanced network handover procedures. Networks (or network devices) and UEs can implement techniques to mitigate network overload with non-subscriber UEs. For example, the network can transmit a broadcast message instructing the network to accept non-subscriber UEs. In some instances, the broadcast message may be triggered by a disaster that renders the network unavailable. When a network is unavailable, other available networks can transmit broadcast messages to subscribers of the unavailable network. In response to the broadcast message, a non-subscriber UE can transmit a request to connect to one of the available networks. However, in some situations, such as when another available network becomes congested due to the influx of non-subscriber UEs, the network can suppress the transmission of the instruction, and thus, the non-subscriber can suppress its request to connect to the network. In another situation, the network can continue to transmit instructions and continue to receive connection requests from non-subscriber UEs, but the network can transmit a rejection message to each UE requesting a connection. In some other scenarios, the UE may be configured or receive a configuration (e.g., a list of network priorities, a function for calculating access identity) that enables the UE to efficiently determine which network in the set of networks to request a connection to, where the configuration is based on mitigating network overload of one or more networks.

[0008] Similarly, during non-subscriber UE acceptance mode, the base station can transmit an indication that a second network is available as a fallback network when the first network is unavailable, wherein the base station serves the second network. The base station can establish a connection with one or more UEs based on receiving a registration message from one or more UEs in response to the transmitted indication. In some cases, the UE can establish a connection with the second network based on the UE's fallback configuration. The base station can identify the congestion level of the second network, and if the identified congestion level is equal to or greater than a congestion level threshold, and switch to non-subscriber UE rejection mode, wherein the base station refuses to connect to non-subscriber UEs (e.g., disaster-inbound roamers). The handover can be based on a congestion level equal to or greater than a congestion level threshold.

[0009] A method for wireless communication at a UE is described. The method may include: identifying a first network connection that the UE is not subscribed to; identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determining a second network that the UE should connect to in one or more other networks based on the fallback configuration, wherein the UE is not subscribed to any of the one or more other networks; and attempting to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0010] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. These instructions are executable by the processor to cause the apparatus to: identify a first network connection that the UE is not subscribed to; identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determine a second network among one or more other networks that the UE should connect to, with which the UE lacks a subscription; and attempt to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0011] Another device for wireless communication at a UE is described. The device may include: means for identifying a first network connection to which the UE is not subscribed; means for identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; means for determining a second network to which the UE should connect, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and means for attempting to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0012] A non-transient computer-readable medium is described, storing code for wireless communication at a UE. The code may include instructions executable by a processor to: identify a first network connection to which the UE is not subscribed; identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determine a second network to which the UE should connect, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and attempt to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0013] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, identifying the fallback configuration may include operations, features, means, or instructions for identifying a set of one or more networks to which the UE is permitted to switch when the first network may be unavailable, the set of one or more networks being listed based on the priority associated with each network.

[0014] In some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein, determining to connect to the second network may include operations, features, means, or instructions for: identifying a network in a set of one or more networks that is associated with the highest priority, to which the second network is associated; and determining to establish a connection with the second network based on the association of the second network with the highest priority.

[0015] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, determining to connect to the second network may include operations, features, means, or instructions for: identifying, at a first time, a network in a set of one or more networks associated with the highest priority, to which the second network is associated; and at a second time, determining to establish a connection to the second network based on the association of the second network with the highest priority, the duration between the first and second times being randomly calculated within a configured range.

[0016] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the UE may be configured with a set of one or more networks, which are included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identification Module (USIM).

[0017] Some examples of the methods, apparatus (equipment) and non-transient computer-readable media described herein may further include operations, features, devices or instructions for receiving a collection of one or more networks via over-the-air (OTA) procedures, such as UE parameter update procedures or roaming guidance procedures.

[0018] Some examples of the methods, apparatus (equipment) and non-transient computer-readable media described herein may further include operations, features, devices or instructions for determining, based on the attempt, that the second network may currently be unavailable to the UE.

[0019] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, attempting to connect to the second network may include operations, features, means, or instructions for monitoring indications from the second network that the second network may be available as a fallback network when the first network may be unavailable.

[0020] In some examples of methods, apparatus (devices) and non-transient computer-readable media described herein, determining that the second network may currently be unavailable to the UE may include operations, features, means, or instructions for determining that an indication may not be present in a broadcast from the second network.

[0021] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the UE monitors the indication from the second network in a System Information Block (SIB).

[0022] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, determining that the second network may currently be unavailable to the UE may include operations, features, means, or instructions for: transmitting a registration message to the second network; and receiving a rejection message from the second network with a rejection reason indication in response to the registration message.

[0023] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the rejection message includes a backoff timer that instructs the UE to suppress the duration of the attempt to establish a connection with the second network.

[0024] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for transmitting a second registration message to the second network based on the expiration of the backoff timer.

[0025] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for attempting to connect to one of the one or more other networks based on the determination that the second network may currently be unavailable to the UE.

[0026] A method for wireless communication at a UE is described. The method may include: identifying a first network connection that the UE is not subscribed to; identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determining a second network that the UE should connect to in one or more other networks based on the fallback configuration, wherein the UE is not subscribed to any of the one or more other networks; and attempting to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0027] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. These instructions are executable by the processor to cause the apparatus to: identify a first network connection that the UE is not subscribed to; identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determine a second network among one or more other networks that the UE should connect to, with which the UE lacks a subscription; and attempt to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0028] Another device for wireless communication at a UE is described. The device may include: means for identifying a first network connection to which the UE is not subscribed; means for identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; means for determining a second network to which the UE should connect, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and means for attempting to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0029] A non-transient computer-readable medium is described, storing code for wireless communication at a UE. The code may include instructions executable by a processor to: identify a first network connection to which the UE is not subscribed; identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determine a second network to which the UE should connect, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and attempt to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

[0030] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for receiving from the first network a notification that services for the UE may be provided by the one or more other networks via UE roaming, wherein identifying the fallback configuration may be based on the notification from the first network.

[0031] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the notification from the first network indicates that the first network may be unavailable.

[0032] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, identifying the fallback configuration may include operations, features, means or instructions for identifying a set of networks that the UE may be allowed to switch to when the first network may be unavailable, the set of networks being listed based on the priority associated with each network.

[0033] In some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein, determining to connect to the second network may include operations, features, means, or instructions for: identifying a network in the network set associated with the highest priority, to which the second network is associated; and determining to establish a connection with the second network based on the association of the second network with the highest priority.

[0034] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, determining to connect to the second network may include operations, features, means, or instructions for: identifying, at a first time, a network in the network set associated with the highest priority, to which the second network is associated; and at a second time, determining to establish a connection to the second network based on the association of the second network with the highest priority, the duration between the first and second times being randomly calculated within a pre-configured range.

[0035] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the UE may be configured with the network set included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identification Module (USIM).

[0036] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for receiving the network set via over-the-air (OTA) via a UE parameter update procedure or roaming guidance procedure.

[0037] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, receiving the notification from the first network may include operations, features, means, or instructions for the following actions: receiving a deregistration message from the first network instructing the UE to deregister from the first network.

[0038] In some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein, the deregistration message includes a set of networks arranged in a list based on the priority associated with each network or the identifiers of networks to which the UE may connect, and the UE determines whether to connect to the second network based on the deregistration message.

[0039] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, identifying the fallback configuration may include operations, features, means, or instructions for identifying a function used by the UE to determine an access identity, which the UE uses to determine which of the one or more other networks to connect to and connect to the determined network.

[0040] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means, or instructions for performing actions such as calculating a value based on the function that indicates an access identity in a set of access identities, wherein each network may be associated with a particular access identity.

[0041] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means, or instructions for: determining one or more networks associated with the access identity indicated by the calculated value; and determining, based on the association of the second network with the access identity indicated by the calculated value, to establish a connection with the second network.

[0042] Some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein may further include operations, features, means, or instructions for: determining that there may be no available network that can be associated with the access identity indicated by the calculated value; and randomly determining, based on the determination that there may be no available network that can be associated with the access identity indicated by the calculated value, to connect to a second network among the one or more other networks.

[0043] A method for wireless communication at a UE is described. The method may include: receiving from a first network to which the UE is subscribed a notification that services for the UE will be provided by one or more other networks via UE roaming; assessing the availability of a second network among the one or more other networks based on the notification from the first network, determining based on the assessment that the second network is currently unavailable to the UE; and attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0044] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. These instructions are executable by the processor to cause the apparatus to: receive from a first network to which the UE is subscribed a notification that services to the UE will be provided via UE roaming by one or more other networks; assess the availability of a second network among the one or more other networks based on the notification from the first network; determine, based on the assessment, that the second network is currently unavailable to the UE; and, based on the determination that the second network is currently unavailable to the UE, attempt to connect to one of the one or more other networks.

[0045] Another device for wireless communication at a UE is described. The device may include: means for receiving from a first network to which the UE is subscribed a notification that services for the UE will be provided by one or more other networks via UE roaming; means for assessing the availability of a second network among the one or more other networks based on the notification from the first network; means for determining, based on the assessment, that the second network is currently unavailable to the UE; and means for attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0046] A non-transient computer-readable medium is described, storing code for wireless communication at a UE. The code may include instructions executable by a processor to: receive notification from a first network to which the UE is subscribed that service to the UE will be provided via UE roaming by one or more other networks; assess the availability of a second network among the one or more other networks based on the notification from the first network; determine, based on the assessment, that the second network is currently unavailable to the UE; and, based on the determination that the second network is currently unavailable to the UE, attempt to connect to one of the one or more other networks.

[0047] In some examples of methods, apparatus (devices) and nontransient computer-readable media described herein, assessing the availability of the second network in one or more other networks may include operations, features, means, or instructions for monitoring indications from the second network that the second network may be available as a fallback network when the first network may be unavailable.

[0048] In some examples of methods, apparatus (devices) and non-transient computer-readable media described herein, determining that the second network may currently be unavailable to the UE may include operations, features, means, or instructions for determining that an indication may not be present in a broadcast from the second network.

[0049] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, determining that the second network may currently be unavailable to the UE may include operations, features, means, or instructions for: transmitting a registration message to the second network; and receiving a rejection message from the second network with a rejection reason indication in response to the registration message.

[0050] In some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein, the rejection reason indication indicates that the UE may attempt to connect to a network different from the second network in one or more other networks.

[0051] In some examples of the methods, apparatus (devices) and nontransient computer-readable media described herein, attempting to connect to one of the one or more other networks may include operations, features, means, or instructions for attempting to connect to a third network of the one or more other networks based on the UE receiving the rejection reason indication from the second network.

[0052] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the rejection message includes a backoff timer that instructs the UE to suppress the duration of the attempt to establish a connection with the second network.

[0053] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, attempting to connect to one of the one or more other networks may include operations, features, means, or instructions for transmitting a second registration message to the second network based on the expiration of the backoff timer.

[0054] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the UE monitors the indication from the second network in a System Information Block (SIB).

[0055] A method for wireless communication at a base station is described. The method may include: transmitting, during a non-subscriber UE accept mode, an indication that a second network is available as a fallback network when a first network is unavailable, the base station serving the second network; establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to transmitting the indication; identifying a congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold; and switching from the non-subscriber UE accept mode to a non-subscriber UE rejection mode in which the base station refuses to connect to non-subscriber UEs, the switching being based on the congestion level being equal to or greater than the congestion level threshold.

[0056] An apparatus for wireless communication at a base station is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. These instructions are executable by the processor to cause the apparatus to: transmit, during a non-subscriber UE acceptance mode, an indication that a second network is available as a fallback network when a first network is unavailable, the base station serving the second network; establish a connection with one or more UEs based on receiving a registration message from one or more UEs in response to transmitting the indication; identify a congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold; and switch from the non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to non-subscriber UEs, the switch being based on the congestion level being equal to or greater than the congestion level threshold.

[0057] Another apparatus for wireless communication at a base station is described. The apparatus may include: means for transmitting an indication during a non-subscriber UE acceptance mode regarding the availability of a second network as a fallback network when a first network is unavailable, the base station serving the second network; means for establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to transmitting the indication; means for identifying a congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold; and means for switching from the non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to the non-subscriber UE, the switching being based on the congestion level being equal to or greater than the congestion level threshold.

[0058] A non-transient computer-readable medium is described, storing code for wireless communication at a base station. The code may include instructions executable by a processor to: transmit, during a non-subscriber UE accept mode, an indication that a second network is available as a fallback network when a first network is unavailable, the base station serving the second network; establish a connection with one or more UEs based on receiving a registration message from one or more UEs in response to transmitting the indication; identify a congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold; and switch from the non-subscriber UE accept mode to a non-subscriber UE reject mode, wherein the base station refuses to connect to the non-subscriber UE, the switch being based on the congestion level being equal to or greater than the congestion level threshold.

[0059] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, identifying the congestion level of the second network may include operations, features, means, or instructions for receiving a message from the base station's Access and Mobility Management Function (AMF) instructing the base station to switch to the non-subscriber UE rejection mode.

[0060] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the base station suppresses the transmission of instructions regarding the availability of the second network as a fallback network.

[0061] Examples of the methods, apparatus (devices) and nontransient computer-readable media described herein may further include operations, features, means or instructions for: transmitting an indication during the non-subscriber UE rejection mode regarding the availability of a second network as a fallback network when the first network may be unavailable; receiving a registration message from the one or more UEs in response to transmitting the indication; and transmitting a rejection message to the one or more UEs with an indication of a rejection reason.

[0062] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the rejection message includes an indication that each of the one or more UEs is attempting to connect to a network different from the second network.

[0063] In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the rejection message includes a backoff timer that instructs each of the one or more UEs to suppress the duration of the attempt to establish a connection with the second network.

[0064] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for receiving a second registration message from one or more of the one or more UEs based on the expiration of the backoff timer.

[0065] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, devices or instructions for receiving a notification that the first network subscribed to by one or more UEs may be unavailable and that the one or more UEs may want to attempt to connect to one or more other networks via roaming.

[0066] Some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein may further include operations, features, means or instructions for transmitting an indication during a non-subscriber UE acceptance mode that may be based on receiving a notification that the first network may be unavailable for one or more UE subscriptions. Brief description of the attached diagram

[0068] Figure 1 Examples of wireless communication systems that support technologies for performing network handover operations according to various aspects of this disclosure are explained.

[0069] Figure 2 Examples of wireless communication systems that support technologies for performing network handover operations according to various aspects of this disclosure are explained.

[0070] Figures 3 to 5 An example of a process flow for performing network handover operations, supported by various aspects of this disclosure, is explained.

[0071] Figure 6 and 7 A block diagram of an apparatus supporting technologies for performing network handover operations according to various aspects of this disclosure is shown.

[0072] Figure 8A block diagram of a communication manager supporting technologies for performing network switching operations according to various aspects of this disclosure is shown.

[0073] Figure 9 A diagram of a system including a device supporting technology for performing network switching operations, according to various aspects of this disclosure, is shown.

[0074] Figure 10 and 11 A block diagram of an apparatus supporting technologies for performing network handover operations according to various aspects of this disclosure is shown.

[0075] Figure 12 A block diagram of a communication manager supporting technologies for performing network switching operations according to various aspects of this disclosure is shown.

[0076] Figure 13 A diagram of a system including a device supporting technology for performing network switching operations, according to various aspects of this disclosure, is shown.

[0077] Figures 14 to 18 A flowchart illustrating a method for performing network handover operations, supporting various aspects of this disclosure, is shown.

[0078] Detailed description

[0079] In some wireless communication systems, user equipment (UEs) can be subscribers to a network (e.g., an operator, a Public Land Mobile Network (PLMN)) so that the network can provide service to the UEs. The network can serve a collection of any number of UEs. In some situations, the network may be unable to provide service to all or part of the UEs within its coverage area. For example, a disaster (e.g., a natural disaster, a man-made disaster) may affect the network's ability to serve UEs subscribed to that network. In another example, an operator may be unable to provide sufficient coverage or any coverage in an area (e.g., in a rural area). In either case, UEs belonging to the network may be temporarily unable to connect to the network and may be without service (e.g., disaster-infiltrating roamers). In some implementations, if the network is unable to provide service to UEs subscribed to that network, the UEs can be notified, and the UEs can attempt to obtain service from other networks available in the same location. Such techniques may be referred to as Minimize Service Interruption (MINT) techniques.

[0080] However, in some situations, such as disaster scenarios where the network may be unable to provide service to a large number of UEs in at least one area, a large number of UEs may attempt to switch to other networks in their location that are not affected by the disaster. As a large number of UEs may attempt to register with unaffected networks, one or more of the unaffected networks may become overloaded due to new UEs (e.g., non-subscriber UEs, disaster-inbound roamers) and may be unable to serve all UEs attempting to gain access.

[0081] To ensure that a failure in one network does not lead to congestion and signaling overload in other networks (where no failure has occurred), the UE and / or network (or network equipment, such as a base station) can be configured with procedures supporting efficient operator handover technologies. A base station in an unaffected network can broadcast an indication that it can accept signals from UEs roaming due to a disaster (or some other condition). When the signal is broadcast, the UE (e.g., a disaster-affected roamer) can attempt to join the network. In some cases, when an unaffected network becomes congested, the network can suppress broadcast signals so that UEs suppress their network access requests. In some cases, the congested network can continue to transmit indications, and the UE can continue to attempt to connect to the congested network; however, during these attempts, the congested network can send a registration rejection message to each UE attempting to connect to it. In some implementations, a rejected UE can be directed to connect to a different network, or the UE can wait a duration before attempting to connect to the same network. In some other implementations, the UE can be configured with a set of fallback networks to connect to in the event of a disaster affecting the network to which the UE is subscribed, or when the UE has no other service available. The fallback network set can be indicated as a list of networks sorted by priority, where the UE can first attempt to connect to the network associated with the highest priority. The UE can also randomly interleave its attempts to connect to the network list within a pre-configured range, so that multiple UEs do not attempt to access the network simultaneously.

[0082] In some scenarios, multiple access identities can be configured for disaster situations or other situations where the UE cannot receive services from its serving network. The UE can be configured with a function (e.g., a hash function) that the UE can use to calculate the access identity, which the UE can then use to connect to the network. The access identity may correspond to a specific network that the UE is allowed to join. A hash function can be selected to ensure that roaming UEs (e.g., disaster-infiltrating roamers) are well distributed across available networks. Any of the scenarios described can be arbitrarily combined to ensure that a failure in one network does not lead to congestion and signaling overload in other unaffected networks.

[0083] Specific aspects of the subject matter described herein can be implemented to achieve one or more advantages. The described techniques can support improvements in network handover procedures performed by roaming UEs by mitigating network congestion, improving reliability, and enhancing efficiency, among other things. Thus, the supported techniques can include improved network operation, and in some examples, enhanced network efficiency, and other benefits.

[0084] The aspects of this disclosure are initially described in the context of a wireless communication system. Subsequently, aspects relating to process flow are described. The aspects of this disclosure are further explained and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to the technology used to perform network handover operations.

[0085] Figure 1 Examples of wireless communication systems 100 supporting technologies for performing network handover operations according to various aspects of this disclosure are described. Wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low latency communication, communication with low-cost and low-complexity devices, or any combination thereof.

[0086] Base station 105 can be distributed across a geographical area to form wireless communication system 100, and can be different types of devices or devices with different capabilities. Base station 105 and UE 115 can communicate wirelessly via one or more communication links 125. Each base station 105 can provide a coverage area 110, and UE 115 and base station 105 can establish one or more communication links 125 on the coverage area 110. Coverage area 110 can be an example of a geographical area over which base station 105 and UE 115 can support signal communication according to one or more radio access technologies.

[0087] Each UE 115 can be distributed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 can be stationary or mobile, or stationary and mobile at different times. Each UE 115 can be a different type of device or a device with different capabilities. Figure 1 The document describes some example UE 115s. The UE 115 described herein can communicate with various types of devices, such as other UE 115s, base station 105, or network equipment (e.g., core network nodes, relay equipment, integrated access and backhaul (IAB) nodes, or other network equipment). Figure 1As shown in the image.

[0088] Each base station 105 may communicate with the core network 130, or with each other, or both. For example, base station 105 may interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). Base stations 105 may communicate with each other directly (e.g., directly between base stations 105), indirectly (e.g., via the core network 130), or directly and indirectly on backhaul links 120 (e.g., via X2, Xn, or other interfaces). In some examples, backhaul link 120 may be or include one or more radio links.

[0089] One or more of the base stations 105 described herein may include, or may be referred to by those skilled in the art as, base transceiver station, radio base station, access point, radio transceiver, B node, evolved B node (eNB), next-generation B node or gigabit B node (any of which may be referred to as gNB), home B node, home evolved B node, or other suitable terms.

[0090] UE 115 may include or be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or any other suitable term, wherein "device" may also be referred to as a unit, station, terminal, or client, etc. UE 115 may also include or be referred to as a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, UE 115 may include or be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine-type communication (MTC) device, which may be implemented in various objects such as appliances or vehicles, meters, etc.

[0091] The UE 115 described herein can communicate with various types of devices, such as other UEs 115 that sometimes act as relays, as well as base station 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, relay base stations, etc. Figure 1 As shown in the image.

[0092] UE 115 and base station 105 can wirelessly communicate with each other via one or more communication links 125 on one or more carriers. The term "carrier" can refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communication link 125. For example, a carrier for communication link 125 may include a portion of the radio spectrum band (e.g., a bandwidth portion (BWP)) operating according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating carrier operation, user data, or other signaling. Wireless communication system 100 may support communication with UE 115 using carrier aggregation or multi-carrier operation. UE 115 may be configured to have multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used in conjunction with both frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0093] In some examples (e.g., in a carrier aggregation configuration), the carrier may also have acquisition signaling or control signaling to coordinate the operation of other carriers. The carrier may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be located according to a channel grid for discovery by UE 115. The carrier may operate in an autonomous mode in which initial acquisition and connection can be performed by UE 115 via that carrier, or in a non-autonomous mode in which the carrier may connect to carriers anchored using different carriers (e.g., different carriers of the same or different radio access technologies).

[0094] The communication link 125 shown in the wireless communication system 100 may include uplink transmission from UE 115 to base station 105, or downlink transmission from base station 105 to UE 115. The carrier may carry downlink or uplink communication (e.g., in FDD mode), or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0095] A carrier may be associated with a specific bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth may be one of several defined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz) of a carrier for a particular radio access technology. Devices of the wireless communication system 100 (e.g., base station 105, UE 115, or both) may have a hardware configuration that supports communication over a specific carrier bandwidth, or may be configurable to support communication over a single carrier bandwidth within a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 or UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate over a portion (e.g., a subband, BWP) or all of the carrier bandwidth.

[0096] The signal waveform transmitted on the carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform extended OFDM (DFT-S-OFDM)). In a system employing MCM, a resource element may include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the code rate of the modulation scheme, or both). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate the UE 115 can achieve. Wireless communication resources can refer to a combination of radio frequency spectrum resources, temporal resources, and spatial resources (e.g., spatial layers or beams), and using multiple spatial layers can further improve the data rate or data integrity of communication with the UE 115.

[0097] The time interval of base station 105 or UE 115 can be expressed as a multiple of a basic time unit, such as the sampling period T. s =1(Δf max ·N f ) seconds, where Δf max This can represent the maximum supported subcarrier spacing, while N f This can represent the maximum supported Discrete Fourier Transform (DFT) size. The time interval of the communication resources can be organized according to radio frames, each with a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a System Frame Number (SFN) (e.g., ranging from 0 to 1023).

[0098] Each frame may include multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may (e.g., in the time domain) be divided into subframes, and each subframe may be further divided into several time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include several symbol periods (e.g., depending on the length of the cyclic prefix added before each symbol period). In some wireless communication systems 100, time slots may be further divided into multiple mini-time slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N) symbols. f (Number) sampling periods. The duration of a symbol period can depend on the subcarrier interval or the operating frequency band.

[0099] A subframe, time slot, mini-slot, or symbol can be the smallest scheduling unit of the wireless communication system 100 (e.g., in the time domain) and can be referred to as a transmission time interval (TTI). In some examples, the duration of the TTI (e.g., the number of symbol periods in the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 can be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0100] Physical channels can be multiplexed on a carrier using various techniques. Physical control channels and physical data channels can be multiplexed on a downlink carrier, for example, using one or more of time-division multiplexing (TDM), frequency-division multiplexing (FDM), or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for physical control channels can be defined by the number of symbol periods and can extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESET) can be configured for a group of UEs 115. For example, one or more UEs 115 can monitor or search control regions for control information based on one or more search space sets, and each search space set can include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for control channel candidates can refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with coded information in a control information format having a given payload size. The search space set may include a common search space set configured to send control information to multiple UEs 115 and a UE-specific search space set configured to send control information to a specific UE 115.

[0101] In some examples, base station 105 may be mobile, and thus provide communication coverage to mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. Wireless communication system 100 may include, for example, a heterogeneous network, in which different types of base stations 105 use the same or different radio access technologies to provide coverage to various geographic coverage areas 110.

[0102] Wireless communication system 100 may be configured to support ultra-reliable communication or low latency communication, or various combinations thereof. For example, wireless communication system 100 may be configured to support ultra-reliable low latency communication (URLLC) or mission-critical communication. UE 115 may be designed to support ultra-reliable, low latency, or mission-critical functions (e.g., mission-critical functions). Ultra-reliable communication may include private or group communication and may be supported by one or more mission-critical services, such as Mission-Critical Talk-to-Talk (MCPTT), Mission-Critical Video (MCVideo), or Mission-Critical Data (MCData)). Support for mission-critical functions may include prioritization of services, and mission-critical services may be used for public safety or general business applications. The terms ultra-reliable, low latency, mission-critical, and ultra-reliable low latency are used interchangeably herein.

[0103] In some examples, UE 115 may also be able to communicate directly with other UE 115 on a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UE 115s utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other UE 115s in such a group may be outside the geographic coverage area 110 of base station 105 or may be unable to receive transmissions from base station 105 for other reasons. In some examples, groups of UE 115s communicating via D2D communication may utilize a one-to-many (1:M) system, where each UE 115 transmits to every other UE 115 in the group. In some examples, base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between the individual UE 115s without involving base station 105.

[0104] Core network 130 provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. Core network 130 can be an evolved packet core (EPC) or a 5G core (5GC). The EPC or 5GC may include at least one control plane entity (e.g., a Mobility Management Entity (MME), Access and Mobility Management Function (AMF)) managing access and mobility, and at least one user plane entity (e.g., a Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), or User Plane Function (UPF)) routing packets or interconnecting to external networks. The control plane entity manages non-access stratum (NAS) functions, such as mobility, authentication, and bearer management of UE 115 served by base station 105 associated with core network 130. User IP packets can be delivered through the user plane entity, which provides IP address allocation and other functions. The user plane entity may be connected to one or more network operator IP services 150. The IP service 150 may include access to the Internet, intranet, IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0105] Some network devices (such as base station 105) may include sub-components, such as access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with each UE 115 through one or more other access network transport entities 145, which may be referred to as a radio headend, smart radio headend, or transmit / receive point (TRP). Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio headends and ANCs) or combined into a single network device (e.g., base station 105).

[0106] Wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 MHz to 300 GHz. Generally, the 300 MHz to 3 GHz band is referred to as a UHF band or decimeter band because the wavelengths range from approximately 1 decimeter to 1 meter. UHF waves can be blocked or redirected by buildings and environmental features, but these waves can penetrate various structures sufficiently for macrocells to provide service to UE 115 located indoors. Compared to transmissions using smaller frequencies and longer waves in the lower HF or VHF portions of the spectrum below 300 MHz, UHF wave transmission can be associated with smaller antennas and shorter ranges (e.g., less than 100 km).

[0107] Wireless communication system 100 may utilize both licensed and unlicensed radio spectrum bands. For example, wireless communication system 100 may employ licensed assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in unlicensed frequency bands (such as the 5 GHz Industrial, Scientific, and Medical (ISM) band). When operating in unlicensed radio spectrum bands, devices (such as base station 105 and UE 115) may employ carrier sensing for collision detection and avoidance. In some examples, operation in unlicensed frequency bands may be based on carrier aggregation configuration (e.g., LAA) in coordination with component carriers operating in licensed frequency bands. Operation in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, etc.

[0108] Base station 105 or UE 115 may be equipped with multiple antennas that can be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of base station 105 or UE 115 may be located within one or more antenna arrays or antenna panels that can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some examples, the antennas or antenna arrays associated with base station 105 may be located in different geographical locations. Base station 105 may have an antenna array with several rows and columns of antenna ports that base station 105 can use to support beamforming for communication with UE 115. Similarly, UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted via the antenna ports.

[0109] Beamforming (also known as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting or receiving device (e.g., base station 105, UE 115) to shape or guide an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array such that some signals propagating relative to a particular orientation of the antenna array experience constructive interference, while others experience destructive interference. Adjustments to the signals transmitted via the antenna elements may include the transmitting or receiving device applying amplitude offset, phase offset, or both to the signals carried via the antenna elements associated with that device. The adjustments associated with each antenna element may be defined by a beamforming weight set associated with a particular orientation (e.g., the antenna array relative to the transmitting or receiving device, or relative to some other orientation).

[0110] As described herein, in some situations, such as due to a disaster, a network may be unable to provide service to one or more UEs 115 roaming in one or more locations. In some situations, an unserved UE 115 (e.g., a disaster-infiltrating roamer) may be configured to request access to other networks in the area. To ensure that a failure in one network does not lead to congestion and signaling overload in other networks (where no failure has occurred), UE 115 and / or the network (or network equipment, such as base station 105) may be configured with procedures supporting efficient operator handover technologies. Base station 105 of an unaffected network may broadcast a signal indicating that the base station is able to accept signals from UEs 115 roaming due to a disaster (or some other condition). When this signal is broadcast, UE 115 (e.g., a disaster-infiltrating roamer) may attempt to join the network. In some situations, when an unaffected network becomes congested, the network may suppress the broadcast signal so that UE 115 suppresses its request to access the network. In some scenarios, the congested network may continue to transmit instructions, and UE 115 may continue to attempt to connect to the congested network. However, during these attempts, the congested network may transmit a registration rejection message to each UE 115 attempting to connect to it. In some implementations, a rejected UE 115 may be directed to connect to a different network, or the UE 115 may wait for a period of time before attempting to connect to the same network.

[0111] In some other implementations, UE 115 can be configured with a fallback network set, which UE 115 can connect to in the event of a disaster affecting the networks subscribed to by UE 115 or when UE 115 has no other service. The fallback network set can be indicated as a list of networks ordered by priority, where UE 115 can first attempt to connect to the network associated with the highest priority. UE 115 can also randomly interleave its attempts to connect to the list of networks within a pre-configured range so that multiple UEs do not attempt to access simultaneously. In some cases, multiple access identities can be configured for disaster situations or other situations where UE 115 cannot receive service from its serving network. UE 115 can be configured with a function (e.g., a hash function) that UE 115 can use to calculate the access identity, which UE 115 can then use to connect to the network. The access identity can correspond to a specific network that UE 115 is allowed to join. The hash function can be selected to ensure that roaming UE 115 (e.g., a disaster-introduced roamer) is well distributed across available networks. Any of the scenarios described can be used in combination to ensure that a failure in one network does not cause congestion and signaling overload in other unaffected networks.

[0112] Figure 2Examples of wireless communication systems 200 supporting technologies for performing network handover operations according to various aspects of this disclosure are described. The wireless communication system 200 may include base stations 105-a, 105-b, and 105-c, and UEs 115-a, 115-b, and 115-c, which may be as described in reference... Figure 1 Examples of base station 105 and UE 115 are described. Each base station 105 can serve a geographic coverage area, where these coverage areas may be the same, may overlap, or may be different. In some cases, UEs 115-a, 115-b, 115-c and / or base stations 105-a, 105-b, and 105-c can implement network handover procedures to mitigate network overload.

[0113] In some wireless communication systems, UE 115 may be a subscriber to a network (e.g., an operator, PLMN) so that the network can provide services to UE 115. The network can serve a set of UE 115 including any number of UE 115s. For example, base station 105-a may be a device serving a first network, base station 105-b may be a device serving a second network, and base station 105-c may be a device serving a third network. UE 115-a, UE 115-b, and UE 115-c may all be subscribers to the first network and may be connected to the first network via base station 105-a so that base station 105-a provides services to each of UE 115-a, UE 115-b, and UE 115-c associated with the first network. In some cases, each network may include multiple base stations 105 or network devices, where the multiple base stations may be located in different areas. For example, the network may serve subscriber UE 115s within a primary coverage area (such as within a country). To reach a UE 115 surrounding a country, one or more base stations 105 associated with the network can be deployed nationwide, each of the one or more base stations 105 serving a coverage area smaller than the main coverage area and within the main coverage area. A subscriber UE 115 in the main coverage area can connect to one of the one or more base stations 105 to receive service from the network based on the location of the UE 115 and the base stations 105 associated with the network surrounding the UE 115.

[0114] In some situations, the network may be unable to provide service to UE 115 in all or part of its primary coverage area. In some situations, disaster conditions (e.g., natural disasters, man-made disasters) (such as fires, earthquakes, hurricanes, etc.) can affect the network's ability to serve UE 115 in one or more areas. For example, a fire may affect one or more buildings or structures of the network (e.g., control centers, buildings including the core network, base station 105), which may affect the network's ability to provide service to one or more UE 115s at the location of the fire. For example, a fire may affect one or more base stations 105 in a part of a country; therefore, UE 115s connected to the affected base station 105 in that part of the country may not have service (e.g., disaster-infiltrating roamers), while UE 115s in different parts of the country may continue to receive service from the network via base stations 105 unaffected by the fire. In another situation, the network may be unable to provide sufficient or any coverage in a region of its primary coverage area (e.g., within a country) such as a rural area. Consequently, any UE 115 that subscribes to the network and moves to an area with limited or no coverage may not be able to receive service from the network.

[0115] In some implementations, if a network is unable to provide service to UE 115, which is subscribed to that network, UE 115 can be notified, and UE 115 can attempt to obtain service from other networks available in the same location. This type of technique may be referred to as the MINT technique. For example, UEs 115-a, 115-b, and 115-c can all be subscribers to the first network and can be connected to the first network via base station 105-a. UE 115-a can communicate with base station 105-a via communication link 205-a, UE 115-b can communicate with base station 105-a via communication link 205-b, and UE 115-c can communicate with base station 105-a via communication link 205-c, wherein communication links 205-a, 205-b, and 205-c can each be used as an uplink or downlink communication link. Disaster situations may occur (such as fire 215), which may affect the ability of base station 105-a to provide services to UEs 115-a, 115-b, and 115-c. Consequently, UEs 115-a, 115-b, and 115-c may be unable to communicate with base station 105-a via communication link 205. In some cases, other base stations 105 not associated with the first network may be located in the same area, so UEs 115-a, 115-b, and 115-c may be without service for a certain duration. In such cases, UEs 115-a, 115-b, and 115-c may receive notification from base station 105-a or neighboring base stations 105 (such as base stations 105 associated with another network (e.g., base stations 105-b or 105-c)) that UEs 115-a, 115-b, and 115-c may be unable to receive service from the first network and may attempt to obtain service from other networks available in the same location. The same location can be defined as an area, perimeter, or some other distance associated with UE 115 (e.g., UE 115-a, UE 115-b, UE 115-c) or base station 105 (e.g., base station 105-a).

[0116] In such scenarios, UE 115, upon receiving notification, may attempt to register with one or more other networks in the same location. The access identity may be associated with a disaster situation (e.g., access identity 3 associated with the UE to which the disaster situation applies). Thus, each UE in UE 115 can use its disaster situation access identity to attempt to register with a new network. In some disaster situations, unaffected networks may be configured to transmit an indication to UE 115 via a broadcast message (e.g., a System Information Block (SIB) flag) that the network is acceptable to disaster-affected UE 115 (e.g., a disaster-inbound roamer). For example, an unaffected network located in the same area as an affected network may be notified (by an entity of the affected network or an entity of its own network) that a disaster has affected a first network and transmit this indication. Thus, each UE in disaster-affected UE 115 may monitor indications from one or more networks and attempt to register with one or more networks from which UE 115 received the indication (e.g., by transmitting a registration request message). A network or network device (e.g., base station 105) can receive a registration request from one or more UEs 115 and accept the registration request so that each UE in UE 115 can register and connect to the network.

[0117] However, in some situations, such as disaster scenarios where the network may be unable to provide service to a large number of UEs 115 (e.g., dozens, hundreds, or thousands of UEs 115) in at least one area, a large number of UEs 115 may attempt to switch to other networks in that location that are not affected by the disaster. Because a large number of UEs 115 may attempt to register with unaffected networks, one or more of the unaffected networks may become overloaded due to the new UEs 115 (e.g., non-subscriber UEs 115, disaster-infiltrating roamers) and may be unable to serve all UEs 115 attempting to gain access. For example, UEs 115-a, 115-b, and 115-c may each receive notification that a first network is unable to provide service to each of the UEs 115, and each of the UEs 115 may monitor indications from base station 105-b (of a second network) and / or base station 105-c (of a third network). In some situations, all three UEs in UE 115 may attempt to connect to base station 105-b, and in some situations, may be able to connect to base station 105-b. This may overload base station 105-b in some scenarios, and base station 105-b may be unable to efficiently or reliably serve UE 115 connected to base station 105-b, or accept any additional UE 115.

[0118] To ensure that a failure in one network does not lead to congestion and signaling overload in other networks (where no failure has occurred), UE 115 and / or the network (or network equipment, such as a base station) may be configured with procedures supporting efficient network handover techniques. The efficient network handover techniques described herein can be implemented in disaster situations where one or more networks are affected by a disaster, or in other scenarios where a network is unable to provide service to its subscriber UE 115. In some cases, network handover techniques may include the network or network equipment (such as base station 105) determining that the network as a whole or in one or more locations has become congested (e.g., overloaded). For example, a network that is not affected as a whole may have accepted a large number of UE 115s (via one or more base stations 105) in one or more locations, and the network as a whole has become overloaded. In another example, a network in a certain location may have accepted a large number of UE 115s (via one or more base stations 105), and has become overloaded in that location. The determination that the entire network or the network in one or more locations has become overloaded can be made by the network or network equipment (such as base station 105 that has become overloaded in a certain location).

[0119] Upon determining that the network as a whole or a network at a particular location has become overloaded, the network may decide to suppress transmissions (e.g., via broadcast SIB flags) regarding indications that the network as a whole or at an overloaded location is accepting affected UE 115. For example, as described herein, base station 105-b may be overloaded or may be close to becoming overloaded. Therefore, the second network and / or base station 105-b may decide to suppress transmissions regarding indications that base station 105-b is capable of accepting affected UE 115. Consequently, the affected UE 115 monitoring the indication may not receive the indication from base station 105-b and therefore may not attempt to connect to base station 105-b. In some cases, thresholds may be defined for determining whether the network or a network at a particular location is overloaded. These thresholds may be the number of UEs 115 connected to the network in a certain area, quality of service, the amount of resources the network is using at a certain location, etc. For example, if the network determines that the network or a network at a certain location is below a threshold, the network or network at that location can remain in UE acceptance mode (e.g., non-subscriber UE acceptance mode), where the network can continue to transmit broadcast instructions and continue to allow UE 115 to connect to the network. In another example, if the network determines that the network or a network at a certain location is equal to or above a threshold, the network or network at that location can switch to UE rejection mode (e.g., non-subscriber UE rejection mode), where the network can suppress the transmission of instructions and suppress the acceptance of new UE 115s seeking to connect to the network.

[0120] In some scenarios, a core function of the network (or a core network element) can determine that the network should stop transmitting instructions and trigger a network shutdown. For example, the network can determine that it has reached an overload condition at at least one location, and the network's AMF (e.g., a core network element associated with a registration request) can transmit a message (e.g., an overload start message) to each network device that has reached an overload condition. For example, a second network can determine that base station 105-b has reached an overload condition. The second network's AMF can transmit an overload message to base station 105-b to indicate that base station 105-b has reached an overload condition. In some scenarios, the AMF can include an IE in the overload message indicating an overload response (e.g., an overload response IE) that may include an overload action information element (IE). The overload action IE can be configured to indicate that base station 105-b should at least reject a value (e.g., a new value) for non-subscriber UE 115 (e.g., the overload action IE may indicate rejection of Radio Resource Control (RRC) connection establishment for disaster-introduced roamers). The overload message from the AMF can trigger base station 105 to enter UE rejection mode. As a result of receiving an overload message from the AMF, base station 105-b suppresses the transmission of the indication. The network can enter UE rejection mode and disable the indication (e.g., suppress transmission indication) on a per-cell basis so that the network can target certain areas of congestion. For example, base station 105-b could be the only congested node (e.g., a radio access network (RAN) node) or area within the second network. Thus, the second network can target base station 105-b and disable the indication only at base station 105-b, rather than disabling the indication across the entire network.

[0121] In some situations, such as when the network as a whole or a network at a specific location is determined to be overloaded based on the thresholds described herein, the network may enter a UE rejection mode, but may continue to transmit indications and receive registration requests from non-subscriber UE 115. When operating in UE rejection mode, the network or network device (e.g., base station 105) may reject registration requests (from disaster-inbound roamers). To reject a registration request, the network may transmit a registration rejection message to each UE 115 from which the network device received the registration request, where again, UE rejection mode may be implemented across the entire network or at a specific location (such as some congested base station 105). In some cases, the registration rejection message may indicate a cause value (e.g., an existing cause value for 5GMM), a backoff timer, or both. The cause value may indicate to the UE 115 that receiving the rejection that base station 105 cannot accept the UE 115's registration request because base station 105 is overloaded or nearing overload. A backoff timer can instruct each UE in UE 115 that receives a rejection to suppress attempts to register with the network for a duration (e.g., as the number of slots, symbols, TTIs, etc., or in the form of milliseconds, seconds, minutes, etc.). The duration indicated by the backoff timer can be pre-configured, semi-statically, or dynamically determined by the network or network device (e.g., base station 105). Upon receiving a registration rejection message including a reason value and a backoff timer, UE 115 can attempt to register with a different network, or it can wait until the backoff timer expires and attempt to register with the same network by retransmitting a registration request message. If the network enters UE acceptance mode while the backoff timer is running, the network can accept the UE registration request upon receiving the retransmitted registration request from UE 115. However, if the network remains congested after the timer expires, the network can retransmit a registration rejection message including a reason value, a backoff timer, or both.

[0122] In some cases, a registration rejection message may indicate a cause value (e.g., a new 5GMM cause value) that instructs UE 115 to seek service in another network capable of accepting non-subscriber UE 115 (e.g., a disaster-inbound roamer). Thus, upon receiving a registration rejection message from a second network, UE 115 can monitor broadcast indications from other networks (such as a third network) and attempt to register with the third network based on both the received registration rejection message from the second network and the received broadcast indication.

[0123] In some scenarios, the network can use a combination of registration rejection messages. For example, upon entering UE rejection mode, the network can be configured to first transmit a registration rejection message including a cause value and a backoff timer. Subsequently, if the network receives a second registration message from the same UE 115, and the network is still in UE rejection mode, the network can transmit a registration rejection message instructing UE 115 to seek another network to connect to. As described herein, the network can enter UE rejection mode and transmit registration rejection messages on a per-cell basis so that the network can target certain areas of congestion. For example, base station 105-b could be the only congested node (e.g., a RAN node) or area within the second network. Thus, the second network can target base station 105-b and instruct base station 105-b to enter registration rejection mode, rather than entering UE rejection mode across the entire network.

[0124] In some implementations, UE 115 may be configured with a set of networks (e.g., a set of network IDs, such as PLMN IDs), which UE 115 may attempt to establish a connection with in situations where UE 115's network provider is affected by a disaster or otherwise unable to provide service to UE 115. In some cases, the network may perform negotiation to determine a Service Level Agreement (SLA), which determines which networks are included in the network set for each UE 115. Thus, a network subscriber (e.g., UE 115) may be provided with an SLA-based network set by the network to which UE 115 is subscribed. In some cases, the network set may be configured in a priority-ordered list indicating the priority associated with each network in the list. In some cases, UE 115 may be configured to utilize the network set in disaster situations or some other situation where UE 115 is unable to receive service from its network. In such cases, UE 115 may utilize the network set or the priority-ordered network list to determine which network to send the registration request message to.

[0125] In some implementations, UE 115 may be pre-configured with a network set. For example, the network set may be included in the UE 115's Universal Mobile Telecommunications Service (UMTS) Subscriber Identity Module (USIM), such as in a USIM data file. The network set may be stored in a USIM data file associated with storing disaster situation information (e.g., a new USIM data file, such as a disaster-incoming roaming PLMN selector data file). In some implementations, the network set may be stored in a USIM data file associated with network selection (e.g., an existing USIM data file, such as an operator-controlled PLMN selector data file with access technology). In some implementations, UE 115 may be configured with a network set via over-the-air (OTA) transmission. For example, the network provider of UE 115 may transmit an indication of the network set via a UE parameter update procedure in which UE parameters in the ME or USIM are updated. Thus, the UE parameter update procedure can be used to further configure UE 115 with the network set or to update the network set that UE 115 can use in disaster situations. In another example, the network of UE 115 can transmit instructions for the network set via a roaming guidance procedure in which the network list (e.g., preferably PLMN) at UE 115 can be updated. Thus, the roaming guidance procedure can be used to further configure UE 115 with the network set or update the network set that UE 115 can use in disaster situations.

[0126] In some implementations, a disaster-affected network may redirect a UE 115 served by the network to a specific network (e.g., a PLMN ID) or provide the UE 115 with a set of networks (e.g., a prioritized list of networks) when the disaster condition applies. The network may determine that it is currently in or about to enter a disaster condition, and upon such determination, may transmit a deregistration message to its subscribed UE 115. The deregistration request message may include a cause value (e.g., a new 5GMM cause value) and an IE (e.g., a new IE). The deregistration request may include a specific PLMN ID or a prioritized list of networks (e.g., a list of PLMN IDs).

[0127] When UE 115 is configured with a network set, upon entering a disaster state (or some other state in which UE 115 cannot receive service), UE 115 can use this set to determine which network to attempt to connect to. When UE 115 is configured with a priority-ordered network list, upon entering a disaster state (or some other state in which UE 115 cannot receive service), UE 115 may first attempt to connect to the network associated with the highest priority in the list. If UE 115 cannot connect to the network associated with the highest priority, UE 115 may attempt to connect to the next highest priority network in the list, and so on, until UE 115 is able to connect to a network, or until UE 115 reaches the end of the list. UE 115 can also stagger its attempts to connect to the network list so that multiple UEs do not attempt to access simultaneously. UE 115 can be configured to treat each network in the network set as equivalent to UE 115's original network.

[0128] As described herein, a single access identity can be associated with a disaster situation. In some cases, multiple access identities can be defined and associated with a disaster situation. To determine which access identity UE 115 should use in a disaster situation, UE 115 can be configured with a function (e.g., a hash function) that UE 115 can use to compute the value associated with the access identity. The hash function can be any function that can be used to map data of a certain size to a fixed value. UE 115 can be configured to apply the hash function configured on UE 115 to UE 115's International Mobile Subscriber Identity (IMSI) when in a disaster situation (or some other situation) or before a disaster situation. The output of the hash function can be a value that corresponds to the access identity in the disaster situation. UE 115 can identify the access identity associated with the output of the hash function and use that access identity to determine which network to connect to and connect to the determined network.

[0129] For example, each network may include a prohibition bit mapping associated with access control for UE 115. Each network located in the same location as the disaster may set the prohibition bit mapping for one or more of these access identities to be enabled, such as one of the disaster-related access identities, and set the prohibition bit mapping for the remaining access identities to be disabled. Which access identities a network sets to be enabled may be predetermined (e.g., pre-negotiated between networks). In some cases, which access identities are set to be enabled by the network may be communicated to the network by an external entity (e.g., dynamically communicated) to notify the network that a disaster situation applies. Each network in the area serving the disaster-affected UE 115 may be associated with a different access identity, and the hash function of UE 115 may be configured such that UE 115 is distributed across available access identities and thus across available networks to distribute the load of non-subscriber UE 115 (e.g., disaster-inbound roamers) among available networks unaffected by the disaster. For example, the hash function may classify subscribers (e.g., UE 115) into groups x, where x may be determined based on the number of networks in the location where the disaster occurred.

[0130] UE 115 can determine that it cannot connect to base station 105-a, and can subsequently determine which of one or more available networks UE 115 should attempt to join. UE 115 can be configured to determine one of the access identities in a disaster situation based on a hash function, and thus determine which network to attempt to connect to in a disaster situation. To determine which access identity a network is associated with, UE 115 can check the network's forbidden bit mapping. If the forbidden bit mapping for the access identity calculated by UE 115 is set to enabled, UE 115 can attempt to register with the network. If the forbidden bit mapping for the access identity calculated by UE 115 is set to disabled, the UE can look at the next network to determine the network's access identity (based on the network's forbidden bit mapping). If UE 115 cannot find a network with a matching access identity that is set to open (e.g., because the network associated with that access identity is unavailable in the UE location), UE 115 may randomly select a network from among the available networks in the UE 115 location that accept non-subscriber UE 115 (e.g., disaster-inbound roamers) and may attempt to register with the randomly selected network.

[0131] In some implementations, UE 115 can be configured with a time duration for which UE 115 will wait before attempting to establish a connection with the network. Each UE 115 in the network can be assigned a different duration, or UE 115 can be divided into subsets, and each subset can be assigned a different duration to separate the number of UE 115s attempting to connect to the network once. The duration can be the time after UE 115 determines that it cannot receive service from its network and before UE 115 can attempt to connect to a different network (e.g., as the number of time slots, symbols, TTIs, etc., or as a time duration in the form of milliseconds, seconds, minutes, etc.). The duration can be randomly calculated within a pre-configured range.

[0132] Any of the solutions described herein can be combined with each other in any way to ensure that a failure in one network does not cause congestion and signaling overload in other unaffected networks. For example, UEs 115-a, 115-b, and 115-c may receive notification or otherwise determine that a first network served by base station 105-a is unavailable to provide service to UEs 115-a, 115-b, and 115-c. In some cases, UEs 115 may each be configured with a set of networks that UE 115 may attempt to connect to (e.g., a priority list of networks), or UEs 115 may be configured with functions for determining the access identity for connecting to the network, or combinations thereof. Additionally or alternatively, each UE in UE 115 may be configured to monitor broadcast indications (e.g., via SIB flags) from networks that accept non-subscriber UEs 115 (e.g., disaster-infiltrating roamers). Thus, UEs 115-a, 115-b, and 115-c may each determine the network to attempt to connect to based on indications received from the network, a priority list, a calculated access identity, or a combination thereof.

[0133] For example, UE 115-a can determine and attempt to connect to a third network via base station 105-c by sending a registration request message to base station 105-c. Base station 105-c may not be overloaded and may accept the registration request message to allow UE 115-a to connect to base station 105-c to receive services from base station 105-c via communication link 205-d. Similarly, UE 115-b can determine and attempt to connect to a second network via base station 105-b by sending a registration request message to base station 105-b. Base station 105-b may not be overloaded and may accept the registration request message to allow UE 115-b to connect to base station 105-b to receive services from base station 105-b via communication link 205-e. UE 115-c can initially determine to connect to the second network via base station 105-b by sending a registration request message to base station 105-b. However, base station 105-b may have become overloaded and may have switched to UE denial mode. Therefore, base station 105-b can send a registration rejection message to UE 115-c, and UE 115-c may be unable to establish a communication link 205-f with base station 105-b at this time based on the rejection. Based on the information included in the registration rejection message, UE 115-c may wait for a duration (e.g., based on a backoff timer included in the registration rejection message) before attempting to connect to base station 105-b again, or UE 115-c may be redirected to a third network. For example, the registration rejection message may direct UE 115-c to connect to a third network via base station 105-c. UE 115-c can send a registration request message to base station 105-c. Base station 105-c may not be overloaded and may accept the registration request message to allow UE 115-c to connect to base station 105-c to receive services from base station 105-c via communication link 205-g.

[0134] Figure 3 An example of process flow 300 supporting techniques for performing network handover operations according to various aspects of this disclosure is explained. Process flow 300 can illustrate an example network handover procedure. For example, UE 115-d can perform a network handover procedure with base station 105-d. Base station 105-d and UE 115-d can be referenced Figure 1 and 2 Examples of corresponding wireless devices described. In some cases, instead of UE 115-d performing the network handover procedure, different types of wireless devices (e.g., base station 105) can implement the network handover procedure for UE 115. The following alternative examples can be implemented, some of which may be performed in a different order than described or not at all. In some cases, the steps may include additional features not mentioned below, or further steps may be added.

[0135] At 305, UE 115-d can identify that UE 115-d is not connected to a first network to which UE 115-d has subscribed. In some cases, UE 115-d may receive notification from the first network that service to UE 115-d will be provided by one or more other networks via UE roaming. In some cases, the notification from the first network may indicate that the first network is unavailable. In some implementations, receiving notification from the first network may include UE 115-d receiving a deregistration message from the first network instructing UE 115-d to deregister from that first network. The deregistration message may include a set of networks listed based on the priority associated with each network or the identifier of the network to which UE 115-d wishes to connect (e.g., PLMN ID, network ID). UE 115-d may determine to connect to a second network based on this deregistration message.

[0136] At 310, UE 115-d may identify the fallback configuration to be applied based on an indication that the UE is not connected to the first network. In some cases, identifying the fallback configuration is based on a notification from the first network. In some cases, identifying the fallback configuration may include UE 115-d identifying the set of networks that UE 115-d is allowed to switch to when the first network is unavailable, wherein the set of networks may be arranged in a list based on the priority associated with each network.

[0137] In some implementations, UE 115-d can be configured with a network set, which can be included in UE 115-d's USIM. In some implementations, UE 115-d can receive the network set via OTA through a UE parameter update procedure or a roaming guidance procedure.

[0138] In some scenarios, the fallback configuration may include a function used by UE 115-d to determine an access identity, which UE 115-d uses to determine which of one or more other networks to connect to and connect to that determined network. UE 115-d may calculate a value based on this function, where the value may indicate an access identity in a set of access identities, where each network may be associated with a specific access identity. In some scenarios, UE 115-d may determine one or more networks associated with the access identity indicated by the calculated value. In some scenarios, UE 115-d may determine that no available network exists associated with the access identity indicated by the calculated value.

[0139] At 315, UE 115-d may determine, based on a fallback configuration, a second network to which UE 115-d should connect, which may lack a subscription to any of those networks. In some cases, determining to connect to the second network may include UE 115-d identifying the network in the network set associated with the highest priority (e.g., based on a list), where the second network is associated with the highest priority, and determining to establish a connection with the second network based on this association.

[0140] In some scenarios, determining whether to connect to a second network may involve UE 115-d identifying the network with the highest priority in the network set at a first time (e.g., based on a list), and at a second time determining whether to establish a connection with the second network based on the association of the second network with that highest priority. The duration between the first and second times can be randomly calculated within a pre-configured range to mitigate the number of UE 115s attempting to join a network at once.

[0141] In some implementations, UE 115-d may determine to connect to a second network based on a deregistration message. In some implementations, UE 115-d may determine to establish a connection to a second network based on the association of the second network with an access identity indicated by a calculated value. In some implementations, UE 115-d may randomly determine to connect to a second network from one or more other networks based on the determination that no available network is associated with the access identity indicated by the calculated value.

[0142] At 320, UE 115-d may attempt to connect to a second network based on the fallback configuration and the fact that UE 115-d is not connected to the first network.

[0143] Figure 4 An example of process flow 400 supporting technologies for performing network handover operations according to various aspects of this disclosure is explained. Process flow 400 can illustrate example network handover procedures. For example, UE 115-e can perform a network handover procedure with base station 105-e. Base station 105-e and UE 115-e can be referenced Figures 1 to 3 Examples of corresponding wireless devices described. In some cases, instead of UE 115-e performing network handover procedures, different types of wireless devices (e.g., base station 105) can implement the network handover procedures for UE 115. The following alternative examples can be implemented, some of which may be performed in a different order than described or not at all. In some cases, the steps may include additional features not mentioned below, or further steps may be added.

[0144] At 405, UE 115-e can receive notification from the first network to which UE 115-e is subscribed that services for UE 115-e will be provided by one or more other networks via UE roaming.

[0145] At 410, UE 115-e can assess the availability of a second network among the one or more other networks based on the notification from the first network. In some implementations, assessing the second network may include UE 115-e monitoring indications from the second network regarding its availability as a fallback network when the first network is unavailable. UE 115-e may monitor these indications from the second network in the SIB.

[0146] At 415, UE 115-e may determine, based on an assessment, that the second network is currently unavailable to UE 115-e. In some cases, determining that the second network is unavailable may include UE 115-e determining that the indication is not present in a broadcast from the second network. In some cases, determining that the second network is unavailable may include UE 115-e sending a registration message to the second network and receiving a rejection message from the second network with a rejection reason indication in response to the registration message. The rejection reason indication may indicate that UE 115-e will attempt to connect to one or more other networks that are different from the second network. The rejection message may include a backoff timer that indicates the duration for which UE 115-e will suppress attempts to establish a connection with the second network.

[0147] At 420, UE 115-e may attempt to connect to one of one or more other networks based on the determination that the second network is currently unavailable to UE 115-e. UE 115-e may then attempt to connect to a third network among the one or more other networks based on the fact that the UE has received a rejection reason indication from the second network. In some cases, attempting to connect to one of the one or more other networks may include UE 115-e sending a second registration message to the second network based on the expiration of a backoff timer.

[0148] Figure 5 An example of process flow 500 supporting technologies for performing network handover operations according to various aspects of this disclosure is explained. Process flow 500 can illustrate example network handover procedures. For example, UE 115-f can perform a network handover procedure with base station 105-f. Base station 105-f and UE 115-f can be referenced Figures 1 to 4Examples of corresponding wireless devices described. In some cases, instead of UE 115-f performing the network handover procedure, different types of wireless devices (e.g., base station 105) can implement the network handover procedure for UE 115. The following alternative examples can be implemented, some of which may be performed in a different order than described or not at all. In some cases, the steps may include additional features not mentioned below, or further steps may be added.

[0149] At point 505, base station 105-f may transmit an indication during non-subscriber UE acceptance mode that a second network is available as a fallback network when the first network is unavailable, wherein base station 105-f serves the second network. In some implementations, base station 105-f may receive notification that a first network subscribed to by one or more UEs 115 is unavailable and that the one or more UEs 115 will attempt to connect to one or more other networks via roaming. In some cases, the indication transmitted during non-subscriber UE acceptance mode is based on receiving notification that the first network subscribed to by one or more UEs is unavailable.

[0150] At 510, base station 105-f can establish a connection with one or more UEs 115 (such as UE 115-f) by receiving a registration message from one or more UEs 115 in response to a transmission instruction.

[0151] At point 515, base station 105-f can identify the congestion level of the second network, and the identified congestion level is equal to or greater than a congestion level threshold. In some cases, identifying the congestion level of the second network may include base station 105-f receiving a message from its AMF instructing base station 105-f to switch to a non-subscriber UE rejection mode. Base station 105-f may suppress the transmission of indications regarding the availability of the second network as a fallback network.

[0152] At point 520, base station 105-f can switch from non-subscriber UE accept mode to non-subscriber UE reject mode, where base station 105-f rejects connection with non-subscriber UE 115. The handover can be based on a congestion level equal to or greater than a congestion level threshold.

[0153] In some scenarios, base station 105-f may transmit an indication during a non-subscriber UE rejection mode that a second network is available as a fallback network when the first network is unavailable. Base station 105-f may receive a registration message from one or more UEs 115 in response to the transmission indication, and transmit a rejection message to the one or more UEs 115 with a rejection reason indication. The rejection message may include an indication that each of the one or more UEs is attempting to connect to a network different from the second network. The rejection message may include a backoff timer indicating the duration for which each of the one or more UEs will suppress attempts to establish a connection with the second network. In some scenarios, base station 105-f may receive a second registration message from one or more of the one or more UEs based on the expiration of the backoff timer.

[0154] Figure 6 A block diagram 600 of a device 605 supporting technologies for performing network handover operations according to various aspects of this disclosure is shown. Device 605 may be an example of various aspects of UE 115 as described herein. Device 605 may include a receiver 610, a transmitter 615, and a communication manager 620. Device 605 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0155] Receiver 610 may provide means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to technologies used for performing network handover operations). The information may be transmitted to other components of device 605. Receiver 610 may utilize a single antenna or a collection of multiple antennas.

[0156] Transmitter 615 may provide means for transmitting signals generated by other components of device 605. For example, transmitter 615 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to techniques for performing network handover operations), user data, control information, or any combination thereof. In some examples, transmitter 615 may be co-located with receiver 610 in a transceiver module. Transmitter 615 may utilize a single antenna or a collection of multiple antennas.

[0157] The communication manager 620, receiver 610, transmitter 615, or various combinations thereof, or various components thereof, may be examples of means for performing various aspects of the techniques described herein for performing network handover operations. For example, the communication manager 620, receiver 610, transmitter 615, or various combinations thereof, or components thereof, may support methods for performing one or more functions described herein.

[0158] In some examples, the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuitry system). This hardware may include a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, configured to or otherwise support means for performing the functions described herein. In some examples, the processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by executing instructions stored in memory by the processor).

[0159] Additionally or alternatively, in some examples, the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be implemented by code executed by a processor (e.g., as communication management software or firmware). If implemented by code executed by a processor, the functionality of the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be performed by a general-purpose processor, DSP, central processing unit (CPU), ASIC, FPGA, or any combination of these or other programmable logic devices (e.g., means configured or otherwise supported for performing the functions described in this disclosure).

[0160] In some examples, the communication manager 620 may be configured to use or otherwise cooperate with the receiver 610, transmitter 615, or both to perform various operations (e.g., receiving, monitoring, transmitting). For example, the communication manager 620 may receive information from the receiver 610, send information to the transmitter 615, or be integrated with the receiver 610, transmitter 615, or both to receive information, transmit information, or perform various other operations described herein.

[0161] According to the examples disclosed herein, the communication manager 620 may support wireless communication at the UE. For example, the communication manager 620 may be configured or otherwise support means for: identifying a first network connection that the UE is not subscribed to; identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determining a second network, based on the fallback configuration, that the UE lacks a subscription to any of those networks; and attempting to connect to the second network based on the fallback configuration and the UE's lack of a connection to the first network.

[0162] Additionally or alternatively, the communication manager 620 may support wireless communication at the UE according to the examples disclosed herein. For example, the communication manager 620 may be configured or otherwise support means for: receiving notification from a first network to which the UE is subscribed regarding services to that UE that will be provided via roaming by one or more other networks. The communication manager 620 may be configured or otherwise support means for: assessing the availability of a second network among one or more other networks based on notifications from the first network. The communication manager 620 may be configured or otherwise support means for: determining, based on the assessment, that the second network is currently unavailable to the UE. The communication manager 620 may be configured or otherwise support means for: attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0163] By including or configuring a communication manager 620 according to an example as described herein, device 605 (e.g., a processor that controls or otherwise couples to receiver 610, transmitter 615, communication manager 620, or a combination thereof) can support techniques for efficient network handover operations. For example, communication manager 615 as described herein can be implemented to achieve one or more potential advantages. One implementation can allow device 605 to more efficiently determine the network to be switched to without overloading that network. For example, device 605 may be unable to receive service from its network provider, and device 605 can perform a network handover operation so that the network in the same area does not become overloaded.

[0164] Based on the network handover technology described herein, the processor of UE 115 (e.g., controls receiver 610, transmitter 620, or as referred to herein) Figure 9 The described transceiver 920 can improve the reliability and efficiency of the UE 115 in the handover procedure from one network to another.

[0165] Figure 7 A block diagram 700 of a device 705 supporting technologies for performing network handover operations according to various aspects of this disclosure is shown. Device 705 may be an example of aspects of device 605 or UE 115 as described herein. Device 705 may include a receiver 710, a transmitter 715, and a communication manager 720. Device 705 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0166] Receiver 710 may provide means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to technologies used for performing network handover operations). The information may be transmitted to other components of device 705. Receiver 710 may utilize a single antenna or a collection of multiple antennas.

[0167] Transmitter 715 may provide means for transmitting signals generated by other components of device 705. For example, transmitter 715 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to techniques for performing network handover operations), user data, control information, or any combination thereof. In some examples, transmitter 715 may be co-located with receiver 710 in a transceiver module. Transmitter 715 may utilize a single antenna or a collection of multiple antennas.

[0168] Device 705 or its various components may be examples of means for performing various aspects of the techniques described herein for performing network switching operations. For example, communication manager 720 may include connection failure manager 725, rollback configuration manager 730, network switching manager 735, network connection manager 740, service notification manager 745, network availability assessment manager 750, network availability determination manager 755, network connection component 760, or any combination thereof. Communication manager 720 may be examples of various aspects of communication manager 620 as described herein. In some examples, communication manager 720 or its various components may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using receiver 710, transmitter 715, or both, or otherwise cooperating with receiver 710, transmitter 715, or both. For example, communication manager 720 may receive information from receiver 710, send information to transmitter 715, or be integrated in combination with receiver 710, transmitter 715, or both to receive information, transmit information, or perform various other operations described herein.

[0169] According to the examples disclosed herein, the communication manager 720 can support wireless communication at the UE. The connection failure manager 725 can be configured or otherwise supported to identify a first network connection that the UE is not subscribed to. The fallback configuration manager 730 can be configured or otherwise supported to identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network. The network switching manager 735 can be configured or otherwise supported to determine a second network that the UE should connect to, based on the fallback configuration, where the UE lacks a subscription to any of the one or more other networks. The network connection manager 740 can be configured or otherwise supported to attempt to connect to the second network based on the fallback configuration and the UE's lack of connection to the first network.

[0170] Additionally or alternatively, according to the examples disclosed herein, the communication manager 720 may support wireless communication at the UE. The service notification manager 745 may be configured or otherwise support means for receiving notifications from a first network to which the UE is subscribed regarding services to that UE that will be provided via roaming by one or more other networks. The network availability assessment manager 750 may be configured or otherwise support means for assessing the availability of a second network among one or more other networks based on notifications from the first network. The network availability determination manager 755 may be configured or otherwise support means for determining, based on the assessment, that the second network is currently unavailable to the UE. The network connectivity component 760 may be configured or otherwise support means for attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0171] Figure 8A block diagram 800 is shown of a communication manager 820 supporting techniques for performing network handover operations according to various aspects of this disclosure. The communication manager 820 may be an example of the communication manager 620, communication manager 720, or aspects of both described herein. The communication manager 820 or its various components may be examples of means for performing various aspects of the techniques for performing network handover operations as described herein. For example, the communication manager 820 may include a connection failure manager 825, a rollback configuration manager 830, a network handover manager 835, a network connection manager 840, a service notification manager 845, a network availability assessment manager 850, a network availability determination manager 855, a network connection component 860, a notification receiving manager 865, an instruction monitoring manager 870, a deregistration receiving manager 875, an access identity manager 880, a registration transmission manager 885, a rejection receiving manager 890, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0172] According to the examples disclosed herein, the communication manager 820 can support wireless communication at the UE. The connection failure manager 825 can be configured or otherwise supported to identify a first network connection that the UE is not subscribed to. The fallback configuration manager 830 can be configured or otherwise supported to identify a fallback configuration to be applied based on the identification that the UE is not connected to the first network. The network switching manager 835 can be configured or otherwise supported to determine a second network that the UE should connect to, based on the fallback configuration, where the UE lacks a subscription to any of the one or more other networks. The network connection manager 840 can be configured or otherwise supported to attempt to connect to the second network based on the fallback configuration and the UE's lack of connection to the first network.

[0173] In some examples, the notification receiving component 865 may be configured or otherwise support means for receiving a notification from a first network regarding that services to the UE will be provided via UE roaming by one or more other networks, wherein the identification fallback configuration is based on the notification from the first network. In some examples, the notification from the first network indicates that the first network is unavailable.

[0174] In some examples, to support identifying fallback configurations, the fallback configuration manager 830 may be configured or otherwise supported to identify the set of networks that the UE is allowed to switch to when a first network is unavailable, the set of networks being listed based on the priority associated with each network.

[0175] In some examples, to support the determination to connect to a second network, the fallback configuration manager 830 may be configured or otherwise supported to identify the network in the network set associated with the highest priority, with the second network associated with that highest priority. In some examples, to support the determination to connect to a second network, the network connection manager 840 may be configured or otherwise supported to determine to establish a connection to the second network based on the association of the second network with the highest priority.

[0176] In some examples, to support the determination to connect to a second network, the fallback configuration manager 830 may be configured or otherwise supported for the following: at a first time, identifying the network in the network set associated with the highest priority, with the second network associated with that highest priority. In some examples, to support the determination to connect to a second network, the network connection manager 840 may be configured or otherwise supported for the following: at a second time, determining to establish a connection to the second network based on the association of the second network with the highest priority, the duration between the first and second times being pre-configured.

[0177] In some examples, the UE is configured with a network set that is included in the UE's USIM data file.

[0178] In some examples, the fallback configuration manager 830 may be configured or otherwise support devices for receiving network sets via OTA via UE parameter update procedures or roaming guidance procedures.

[0179] In some examples, the network switching manager 835 can monitor indications from the second network that the second network can be used as a fallback network when the first network is unavailable. In some examples, the network switching manager 835 can determine that there is no indication in the broadcast from the second network.

[0180] In some examples, to support receiving notifications from a first network, the deregistration receiving manager 875 may be configured or otherwise supported for receiving a deregistration message from the first network instructing the UE to deregister from that first network. In some examples, the deregistration message includes a set of networks arranged in a list based on the priority associated with each network or the identifier of the network to which the UE wishes to connect, and the UE determines, based on the deregistration message, to connect to a second network.

[0181] In some examples, to support identification fallback configuration, the fallback configuration manager 830 may be configured or otherwise support means for identifying a function used by the UE to determine an access identity, which the UE uses to determine which of one or more other networks to connect to and connect to the determined network. In some examples, the access identity manager 880 may be configured or otherwise support means for calculating a value based on a function that indicates an access identity within a set of access identities, where each network is associated with a specific access identity.

[0182] In some examples, the network switching manager 835 may be configured or otherwise supported to determine one or more networks associated with an access identity indicated by a calculated value. In some examples, the network connection manager 840 may be configured or otherwise supported to determine to establish a connection with a second network based on the association of a second network with an access identity indicated by a calculated value.

[0183] In some examples, the network switching manager 835 may be configured or otherwise supported to determine that no available network exists associated with the access identity indicated by the calculated value. In some examples, the network connection manager 840 may be configured or otherwise supported to randomly determine a second network to connect to from one or more other networks based on the determination that no available network exists associated with the access identity indicated by the calculated value.

[0184] Additionally or alternatively, according to the examples disclosed herein, the communication manager 820 may support wireless communication at the UE. The service notification manager 845 may be configured or otherwise support means for receiving notifications from a first network to which the UE is subscribed regarding services to that UE that will be provided via roaming by one or more other networks. The network availability assessment manager 850 may be configured or otherwise support means for assessing the availability of a second network among one or more other networks based on notifications from the first network. The network availability determination manager 855 may be configured or otherwise support means for determining, based on the assessment, that the second network is currently unavailable to the UE. The network connectivity component 860 may be configured or otherwise support means for attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0185] In some examples, to support the assessment of the availability of a second network in one or more other networks, the monitoring manager 870 is instructed to be configured or otherwise support means for monitoring indications from the second network that the second network can be used as a fallback network when the first network is unavailable.

[0186] In some examples, to support the determination that the second network is currently unavailable to the UE, the monitoring manager 870 may be configured or otherwise supported to determine that an indication is not present in a broadcast from the second network.

[0187] In some examples, to support the determination that the second network is currently unavailable to the UE, the registration transmission manager 885 may be configured or otherwise support means for transmitting a registration message to the second network. In some examples, to support the determination that the second network is currently unavailable to the UE, the rejection reception manager 890 may be configured or otherwise support means for receiving a rejection message with a rejection reason indication from the second network in response to the registration message.

[0188] In some examples, the rejection reason indication instructs the UE to attempt to connect to a network different from the second network in one or more other networks. In some examples, to support attempts to connect to one of the one or more other networks, the network connectivity component 860 may be configured or otherwise support means for attempting to connect to a third network in one or more other networks based on the UE receiving a rejection reason indication from the second network.

[0189] In some examples, the rejection message includes a backoff timer that instructs the UE to suppress the attempt to establish a connection with the second network for a specified duration. In some examples, to support attempts to connect to one of one or more other networks, the registration transmission manager 885 may be configured or otherwise support means for transmitting a second registration message to the second network based on the expiration of the backoff timer.

[0190] In some examples, the UE monitors indications from a second network within the SIB.

[0191] Figure 9A diagram of a system including device 905 supporting technology for performing network handover operations is shown according to various aspects of this disclosure. Device 905 may be an example of device 605, device 705, or UE 115 as described herein, or a component including device 605, device 705, or UE 115. Device 905 may wirelessly communicate with one or more base stations 105, UE 115, or any combination thereof. Device 905 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 920, an input / output (I / O) controller 910, a transceiver 915, an antenna 925, a memory 930, a code 935, and a processor 940. These components may be in electronic communication or otherwise coupled (e.g., operational ground, communication ground, functional ground, electronic ground, electrical ground) via one or more buses (e.g., bus 945).

[0192] I / O controller 910 manages the input and output signals of device 905. I / O controller 910 can also manage peripheral devices not integrated into device 905. In some cases, I / O controller 910 may represent a physical connection or port to an external peripheral device. In some cases, I / O controller 910 may utilize an operating system, such as... MS- MS- OS / Or another known operating system. Additionally or alternatively, the I / O controller 910 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 910 may be implemented as part of a processor (such as processor 940). In some cases, a user may interact with device 905 via the I / O controller 910 or via hardware components controlled by the I / O controller 910.

[0193] In some cases, device 905 may include a single antenna 925. However, in other cases, device 905 may have more than one antenna 925, which may be capable of transmitting or receiving multiple wireless transmissions concurrently. Transceiver 915 may communicate bidirectionally via one or more antennas 925, wired or wireless links, as described herein. For example, transceiver 915 may represent a wireless transceiver and be capable of bidirectional communication with another wireless transceiver. Transceiver 915 may also include a modem for modulating packets and providing modulated packets to one or more antennas 925 for transmission, and for demodulating packets received from one or more antennas 925. Transceiver 915, or transceiver 915 and one or more antennas 925, may be examples of transmitter 615, transmitter 715, receiver 610, receiver 710, or any combination thereof or components thereof as described herein.

[0194] Memory 930 may include random access memory (RAM) and read-only memory (ROM). Memory 930 may store computer-readable, computer-executable code 935, including instructions that, when executed by processor 940, cause device 905 to perform the various functions described herein. Code 935 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, code 935 may not be directly executed by processor 940, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, memory 930 may, in particular, include a basic I / O system (BIOS) that controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0195] Processor 940 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 940 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into processor 940. Processor 940 may be configured to execute computer-readable instructions stored in memory (e.g., memory 930) to cause device 905 to perform various functions (e.g., functions or tasks supporting techniques for performing network switching operations). For example, device 905 or components thereof may include processor 940 and memory 930 coupled to processor 940, wherein processor 940 and memory 930 are configured to perform the various functions described herein.

[0196] According to the examples disclosed herein, the communication manager 920 may support wireless communication at the UE. For example, the communication manager 920 may be configured or otherwise support means for: identifying a first network connection that the UE is not subscribed to; identifying a fallback configuration to be applied based on the identification that the UE is not connected to the first network; determining a second network, based on the fallback configuration, that the UE lacks a subscription to any of those networks; and attempting to connect to the second network based on the fallback configuration and the UE's lack of a connection to the first network.

[0197] Additionally or alternatively, according to the examples disclosed herein, the communication manager 920 may support wireless communication at the UE. For example, the communication manager 920 may be configured or otherwise support means for: receiving notification from a first network to which the UE is subscribed regarding services to that UE that will be provided via roaming by one or more other networks. The communication manager 920 may be configured or otherwise support means for: assessing the availability of a second network among one or more other networks based on notifications from the first network. The communication manager 920 may be configured or otherwise support means for: determining, based on the assessment, that the second network is currently unavailable to the UE. The communication manager 920 may be configured or otherwise support means for: attempting to connect to one of the one or more other networks based on the determination that the second network is currently unavailable to the UE.

[0198] By including or configuring a communication manager 920 according to an example as described herein, device 905 can support technologies for improved communication reliability, reduced latency, and improved user experience related to improved processes (whereby the UE can switch networks when it is unable to receive services from the UE's primary network).

[0199] In some examples, the communication manager 920 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 915, one or more antennas 925, or any combination thereof. Although the communication manager 920 is described as a separate component, in some examples, one or more functions described with reference to the communication manager 920 may be supported or performed by the processor 940, memory 930, code 935, or any combination thereof. For example, code 935 may include instructions executable by the processor 940 to cause the device 905 to perform various aspects of the techniques described herein for performing network switching operations, or the processor 940 and memory 930 may be otherwise configured to perform or support such operations.

[0200] Figure 10 A block diagram 1000 of an apparatus 1005 supporting technologies for performing network handover operations according to various aspects of this disclosure is shown. Apparatus 1005 may be an example of various aspects of base station 105 as described herein. Apparatus 1005 may include a receiver 1010, a transmitter 1015, and a communication manager 1020. Apparatus 1005 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0201] Receiver 1010 may provide means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to technologies for performing network handover operations). The information may be transmitted to other components of device 1005. Receiver 1010 may utilize a single antenna or a collection of multiple antennas.

[0202] Transmitter 1015 may provide means for transmitting signals generated by other components of device 1005. For example, transmitter 1015 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to network handover techniques), user data, control information, or any combination thereof. In some examples, transmitter 1015 may be co-located with receiver 1010 in a transceiver module. Transmitter 1015 may utilize a single antenna or a collection of multiple antennas.

[0203] The communication manager 1020, receiver 1010, transmitter 1015, or various combinations thereof, or various components thereof, may be examples of apparatuses for performing various aspects of the techniques described herein for performing network handover operations. For example, the communication manager 1020, receiver 1010, transmitter 1015, or various combinations thereof, or components thereof, may support methods for performing one or more functions described herein.

[0204] In some examples, the communication manager 1020, receiver 1010, transmitter 1015, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuitry system). The hardware may include processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof, configured to or otherwise support means for performing the functions described herein. In some examples, the processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by executing instructions stored in memory by the processor).

[0205] Additionally or alternatively, in some examples, the communication manager 1020, receiver 1010, transmitter 1015, or various combinations or components thereof, may be implemented by processor-executable code (e.g., as communication management software or firmware). If implemented by processor-executable code, the functionality of the communication manager 1020, receiver 1010, transmitter 1015, or various combinations or components thereof may be performed by a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination of these or other programmable logic devices (e.g., means configured or otherwise supported for performing the functions described in this disclosure).

[0206] In some examples, the communication manager 1020 may be configured to use or otherwise cooperate with the receiver 1010, transmitter 1015, or both to perform various operations (e.g., receiving, monitoring, transmitting). For example, the communication manager 1020 may receive information from the receiver 1010, send information to the transmitter 1015, or be integrated with the receiver 1010, transmitter 1015, or both to receive information, transmit information, or perform various other operations described herein.

[0207] According to the examples disclosed herein, the communication manager 1020 may support wireless communication at a base station. For example, the communication manager 1020 may be configured or otherwise support means for: transmitting an indication during a non-subscriber UE acceptance mode that a second network is available as a fallback network when a first network is unavailable, and the base station serves the second network. The communication manager 1020 may be configured or otherwise support means for: establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to the transmission indication. The communication manager 1020 may be configured or otherwise support means for: identifying the congestion level of the second network, and the identified congestion level being equal to or greater than a congestion level threshold. The communication manager 1020 may be configured or otherwise support means for: switching from a non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to a non-subscriber UE, the switching being based on a congestion level equal to or greater than a congestion level threshold.

[0208] By including or configuring a communication manager 1020 according to an example as described herein, device 1005 (e.g., a processor that controls or otherwise couples to receiver 1010, transmitter 1015, communication manager 1020, or a combination thereof) can support techniques for improving network handover operations by enhancing communication reliability and reducing latency.

[0209] Figure 11 A block diagram 1100 of an apparatus 1105 supporting techniques for performing network handover operations according to aspects of this disclosure is shown. Apparatus 1105 may be an example of aspects of apparatus 1005 or base station 105 as described herein. Apparatus 1105 may include a receiver 1110, a transmitter 1115, and a communication manager 1120. Apparatus 1105 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0210] Receiver 1110 may provide means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to technologies used for performing network handover operations). The information may be transmitted to other components of device 1105. Receiver 1110 may utilize a single antenna or a collection of multiple antennas.

[0211] Transmitter 1115 may provide means for transmitting signals generated by other components of device 1105. For example, transmitter 1115 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to techniques for performing network handover operations), user data, control information, or any combination thereof. In some examples, transmitter 1115 may be co-located with receiver 1110 in a transceiver module. Transmitter 1115 may utilize a single antenna or a collection of multiple antennas.

[0212] Device 1105 or its various components may be examples of means for performing various aspects of the techniques described herein for performing network switching operations. For example, communication manager 1120 may include network availability indication component 1125, connection establishment component 1130, congestion level component 1135, mode switching component 1140, or any combination thereof. Communication manager 1120 may be examples of various aspects of communication manager 1020 as described herein. In some examples, communication manager 1120 or its various components may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using receiver 1110, transmitter 1115, or both, or otherwise in cooperation with receiver 1110, transmitter 1115, or both. For example, communication manager 1120 may receive information from receiver 1110, send information to transmitter 1115, or be integrated with receiver 1110, transmitter 1115, or both to receive information, transmit information, or perform various other operations described herein.

[0213] According to the examples disclosed herein, the communication manager 1120 may support wireless communication at a base station. The network availability indication component 1125 may be configured or otherwise support means for transmitting an indication during a non-subscriber UE acceptance mode that a second network is available as a fallback network when a first network is unavailable, and the base station serves the second network. The connection establishment component 1130 may be configured or otherwise support means for establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to a transmission indication. The congestion level component 1135 may be configured or otherwise support means for identifying the congestion level of the second network, and the identified congestion level is equal to or greater than a congestion level threshold. The mode switching component 1140 may be configured or otherwise support means for switching from a non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to a non-subscriber UE, the switching being based on a congestion level equal to or greater than a congestion level threshold.

[0214] Figure 12 A block diagram 1200 of a communication manager 1220 supporting techniques for performing network handover operations according to various aspects of this disclosure is shown. The communication manager 1220 may be an example of the communication manager 1020, communication manager 1120, or aspects of both described herein. The communication manager 1220 or its various components may be examples of means for performing various aspects of the techniques for performing network handover operations as described herein. For example, the communication manager 1220 may include a network availability indication component 1225, a connection establishment component 1230, a congestion level component 1235, a mode switching component 1240, a network unavailability notification component 1245, a registration receiving component 1250, a transmission rejection component 1255, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0215] According to the examples disclosed herein, the communication manager 1220 may support wireless communication at a base station. The network availability indication component 1225 may be configured or otherwise support means for transmitting an indication during a non-subscriber UE acceptance mode that a second network is available as a fallback network when a first network is unavailable, and the base station serves the second network. The connection establishment component 1230 may be configured or otherwise support means for establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to a transmission indication. The congestion level component 1235 may be configured or otherwise support means for identifying the congestion level of a second network, and the identified congestion level is equal to or greater than a congestion level threshold. The mode switching component 1240 may be configured or otherwise support means for switching from a non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to a non-subscriber UE, the switching being based on a congestion level equal to or greater than a congestion level threshold.

[0216] In some examples, to support identifying the congestion level of the second network, the congestion level component 1235 may be configured or otherwise support means for receiving a message from the base station's AMF instructing the base station to switch to a non-subscriber UE rejection mode. In some examples, the base station suppresses the transmission of instructions regarding the availability of the second network as a fallback network.

[0217] In some examples, the network availability indication component 1225 may be configured or otherwise supported to transmit an indication during a non-subscriber UE rejection mode that a second network is available as a fallback network when a first network is unavailable. In some examples, the registration receiving component 1250 may be configured or otherwise supported to receive a registration message from one or more UEs in response to a transmission indication. In some examples, the rejection transmission component 1255 may be configured or otherwise supported to transmit a rejection message with a rejection reason indication to one or more UEs.

[0218] In some examples, the rejection message includes an indication that each of the one or more UEs attempted to connect to a network different from the second network. In some examples, the rejection message includes a backoff timer that indicates for a certain duration that each of the one or more UEs should suppress attempts to establish a connection with the second network. In some examples, the registration receiving component 1250 may be configured or otherwise support means for receiving a second registration message from one or more of the one or more UEs based on the expiration of the backoff timer.

[0219] In some examples, the network unavailability notification component 1245 may be configured or otherwise support means for receiving a notification that a first network is unavailable for one or more UE subscriptions and that the one or more UEs intend to attempt to connect to one or more other networks via roaming. In some examples, the transmission of an indication during a non-subscriber UE acceptance mode is based on receiving a notification that a first network is unavailable for one or more UE subscriptions.

[0220] Figure 13 A diagram of a system 1300 including a device 1305 supporting technologies for performing network handover operations, according to various aspects of this disclosure, is shown. Device 1305 may be an example of device 1005, device 1105, or base station 105 as described herein, or a component including such devices. Device 1305 may wirelessly communicate with one or more base stations 105, UE 115, or any combination thereof. Device 1305 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 1320, a network communication manager 1310, a transceiver 1315, an antenna 1325, a memory 1330, code 1335, a processor 1340, and an inter-station communication manager 1345. These components may be in electronic communication or otherwise coupled (e.g., operational ground, communication ground, functional ground, electronic ground, electrical ground) via one or more buses (e.g., bus 1350).

[0221] The network communication manager 1310 can manage communication with the core network 130 (e.g., via one or more wired backhaul links). For example, the network communication manager 1310 can manage the delivery of data communication to client devices (such as one or more UEs 115).

[0222] In some cases, device 1305 may include a single antenna 1325. However, in other cases, device 1305 may have more than one antenna 1325, which may be capable of transmitting or receiving multiple wireless transmissions concurrently. Transceiver 1315 may communicate bidirectionally via one or more antennas 1325, wired or wireless links, as described herein. For example, transceiver 1315 may represent a wireless transceiver and be capable of bidirectional communication with another wireless transceiver. Transceiver 1315 may also include a modem for modulating packets and providing modulated packets to one or more antennas 1325 for transmission, and for demodulating packets received from one or more antennas 1325. Transceiver 1315, or transceiver 1315 and one or more antennas 1325, may be an example of transmitter 1015, transmitter 1115, receiver 1010, receiver 1110, or any combination thereof or components thereof as described herein.

[0223] Memory 1330 may include RAM and ROM. Memory 1330 may store computer-readable, computer-executable code 1335, including instructions that, when executed by processor 1340, cause device 1305 to perform the various functions described herein. Code 1335 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, code 1335 may not be directly executable by processor 1340, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, memory 1330 may, in particular, include a BIOS that controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0224] Processor 1340 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 1340 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into processor 1340. Processor 1340 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1330) to cause device 1305 to perform various functions (e.g., functions or tasks supporting techniques for performing network switching operations). For example, device 1305 or components thereof may include processor 1340 and memory 1330 coupled to processor 1340, wherein processor 1340 and memory 1330 are configured to perform the various functions described herein.

[0225] Inter-site communication manager 1345 manages communication with other base stations 105 and may include a controller or scheduler for cooperating with other base stations 105 to control communication with UE 115. For example, inter-site communication manager 1345 may coordinate the scheduling of transmissions to UE 115 for various interference mitigation techniques, such as beamforming or joint transmission. In some examples, inter-site communication manager 1345 may provide an X2 interface within LTE / LTE-A wireless communication network technology to facilitate communication between base stations 105.

[0226] According to the examples disclosed herein, the communication manager 1320 may support wireless communication at a base station. For example, the communication manager 1320 may be configured or otherwise support means for: transmitting an indication during a non-subscriber UE acceptance mode that a second network is available as a fallback network when a first network is unavailable, and the base station serves the second network. The communication manager 1320 may be configured or otherwise support means for: establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to the transmission indication. The communication manager 1320 may be configured or otherwise support means for: identifying the congestion level of the second network, and the identified congestion level being equal to or greater than a congestion level threshold. The communication manager 1320 may be configured or otherwise support means for: switching from a non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to a non-subscriber UE, the switching being based on a congestion level equal to or greater than a congestion level threshold.

[0227] By including or configuring a communication manager 1320 according to an example as described herein, device 1305 can support technologies for improved communication reliability, reduced latency, and improved user experience related to improved processes (whereby the UE can switch networks when it is unable to receive services from its primary network).

[0228] In some examples, the communication manager 1320 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 1315, one or more antennas 1325, or any combination thereof. Although the communication manager 1320 is described as a separate component, in some examples, one or more functions described with reference to the communication manager 1320 may be supported or performed by the processor 1340, memory 1330, code 1335, or any combination thereof. For example, code 1335 may include instructions executable by the processor 1340 to cause the device 1305 to perform various aspects of the techniques described herein for performing network switching operations, or the processor 1340 and memory 1330 may be otherwise configured to perform or support such operations.

[0229] Figure 14 A flowchart illustrating a method 1400 for performing network handover operations, according to various aspects of this disclosure, is shown. The operation of method 1400 can be implemented by a UE or its components as described herein. For example, the operation of method 1400 can be implemented by, as referred to... Figures 1 to 9The UE 115 described herein is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the described function. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described function.

[0230] At 1405, the method may include identifying a first network connection that the UE is not subscribed to. The operation of 1405 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1405 may be provided by reference to [reference needed]. Figure 8 The described connection fault manager 825 is used to perform this.

[0231] At 1410, the method may include identifying a fallback configuration to be applied based on the identifier that the UE is not connected to the first network. The operation of 1410 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1410 may be provided by reference to... Figure 8 The described rollback configuration manager 830 is used to execute this.

[0232] At 1415, the method may include determining, based on a fallback configuration, a second network with which the UE should connect, to which the UE lacks a subscription for any of the one or more other networks. The operation of 1415 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1415 may be derived from, as referenced... Figure 8 The network switching manager 835 described is used to perform this.

[0233] At 1420, the method may include attempting to connect to a second network based on a fallback configuration and the UE not being connected to the first network. The operation at 1420 may be performed according to the examples disclosed herein. In some examples, aspects of the operation at 1420 may be provided as referenced. Figure 8 The network connection manager 840 described is used to perform this.

[0234] Figure 15 A flowchart illustrating a method 1500 for performing network handover operations, according to various aspects of this disclosure, is shown. The operation of method 1500 can be implemented by a UE or its components as described herein. For example, the operation of method 1500 can be implemented by, as referred to... Figures 1 to 9 The UE 115 described herein is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the described function. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described function.

[0235] At 1505, the method may include receiving notification from a first network to which the UE is subscribed that services for the UE will be provided by one or more other networks via UE roaming. Operation of 1505 may be performed according to the examples disclosed herein. In some examples, aspects of operation of 1505 may be provided by reference to [reference needed]. Figure 8 The described service notification manager 845 is used to execute this.

[0236] At 1510, the method may include assessing the availability of a second network in one or more other networks based on notifications from the first network. The operation of 1510 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1510 may be provided by reference to... Figure 8 The Network Availability Assessment Manager 850 described is used to perform this.

[0237] At point 1515, the method may include determining, based on an assessment, that the second network is currently unavailable to the UE. The operation of point 1515 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of point 1515 may be derived from, as referenced... Figure 8 The described network availability determination manager 855 is used to perform this.

[0238] At 1520, the method may include attempting to connect to one of one or more other networks based on determining that a second network is currently unavailable to the UE. The operation of 1520 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1520 may be derived from, as referenced... Figure 8 The network connectivity component 860 described is used to perform this.

[0239] Figure 16 A flowchart illustrating a method 1600 for performing network handover operations, according to various aspects of this disclosure, is shown. The operation of method 1600 can be implemented by a UE or its components as described herein. For example, the operation of method 1600 can be implemented by, as referred to... Figures 1 to 9 The UE 115 described herein is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the described function. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described function.

[0240] At 1605, the method may include receiving notification from a first network to which the UE is subscribed that services for the UE will be provided by one or more other networks via UE roaming. Operation of 1605 may be performed according to the examples disclosed herein. In some examples, aspects of operation of 1605 may be provided by reference to... Figure 8 The described service notification manager 845 is used to execute this.

[0241] At 1610, the method may include assessing the availability of a second network in one or more other networks based on notifications from the first network. The operation of 1610 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1610 may be provided by reference to... Figure 8 The Network Availability Assessment Manager 850 described is used to perform this.

[0242] At 1615, the method may include monitoring indications from a second network regarding its availability as a fallback network when the first network is unavailable. The operation of 1615 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1615 may be determined by reference to [reference needed]. Figure 8 The described instructions are given to monitor manager 870 to execute.

[0243] At 1620, the method may include determining that an indication is absent in the broadcast from the second network. The operation of 1620 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1620 may be determined by, as referenced... Figure 8 The described instructions are given to monitor manager 870 to execute.

[0244] At 1625, the method may include determining, based on an assessment, that the second network is currently unavailable to the UE. The operation of 1625 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1625 may be derived from, as referenced... Figure 8 The described network availability determination manager 855 is used to perform this.

[0245] At 1630, the method may include, based on determining that a second network is currently unavailable to the UE, attempting to connect to one of one or more other networks. The operation of 1630 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1630 may be derived from, as referenced... Figure 8 The network connectivity component 860 described is used to perform this.

[0246] Figure 17 A flowchart illustrating a method 1700 for performing network handover operations, according to various aspects of this disclosure, is shown. The operation of method 1700 can be implemented by a UE or its components as described herein. For example, the operation of method 1700 can be implemented by, as referred to... Figures 1 to 9 The UE 115 described herein is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the described function. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described function.

[0247] At 1705, the method may include receiving notification from a first network to which the UE is subscribed that services for the UE will be provided by one or more other networks via UE roaming. Operation of 1705 may be performed according to the examples disclosed herein. In some examples, aspects of operation of 1705 may be provided by reference to [reference needed]. Figure 8 The described service notification manager 845 is used to execute this.

[0248] At 1710, the method may include assessing the availability of a second network in one or more other networks based on notifications from the first network. The operation of 1710 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1710 may be provided by reference to... Figure 8 The Network Availability Assessment Manager 850 described is used to perform this.

[0249] At 1715, the method may include monitoring indications from a second network regarding its availability as a fallback network when the first network is unavailable. The operation of 1715 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1715 may be determined by reference to [reference needed]. Figure 8 The described instructions are given to monitor manager 870 to execute.

[0250] At 1720, the method may include transmitting a registration message to a second network. The operation of 1720 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1720 may be provided as referenced. Figure 8 The described registration transfer manager 885 is used to execute this.

[0251] At 1725, the method may include receiving a rejection message with a rejection reason indication from a second network in response to a registration message. The operation of 1725 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1725 may be provided by reference to... Figure 8 The described rejection receiver 890 is used to execute this.

[0252] At 1730, the method may include determining, based on an assessment, that the second network is currently unavailable to the UE. The operation of 1730 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1730 may be derived from, as referenced... Figure 8 The described network availability determination manager 855 is used to perform this.

[0253] At 1735, the method may include attempting to connect to one of one or more other networks based on determining that a second network is currently unavailable to the UE. The operation of 1735 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1735 may be derived from, as referenced... Figure 8The network connectivity component 860 described is used to perform this.

[0254] Figure 18 A flowchart illustrating a method 1800 for performing network handover operations, according to various aspects of this disclosure, is shown. The operation of method 1800 can be implemented by a base station or its components as described herein. For example, the operation of method 1800 can be implemented by, as referred to... Figures 1 to 5 and Figures 10 to 13 The described base station 105 performs this function. In some examples, the base station may execute a set of instructions to control the functional elements of the base station to perform the described function. Alternatively or additionally, the base station may use dedicated hardware to perform aspects of the described function.

[0255] At 1805, the method may include transmitting, during a non-subscriber UE acceptance mode, an indication that a second network is available as a fallback network when the first network is unavailable, and the base station serves the second network. Operation of 1805 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1805 may be described by reference to... Figure 12 The network availability description is used to instruct component 1225 to perform this action.

[0256] At 1810, the method may include establishing a connection with one or more UEs based on receiving a registration message from one or more UEs in response to a transmission indication. The operation of 1810 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1810 may be provided by reference to... Figure 12 The described connection establishment component 1230 is used to perform this.

[0257] At 1815, the method may include identifying the congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold. The operation of 1815 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1815 may be provided by reference to... Figure 12 The congestion level component 1235 described is used to perform this.

[0258] At 1820, the method may include switching from a non-subscriber UE accept mode to a non-subscriber UE reject mode, wherein the base station refuses to connect to the non-subscriber UE, the switching being based on a congestion level equal to or greater than a congestion level threshold. The operation of 1820 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1820 may be provided by reference to [reference needed]. Figure 12 The described mode switching component 1240 is used to perform this.

[0259] The following provides an overview of the various aspects of this disclosure:

[0260] Aspect 1: A method for wireless communication at a UE, comprising: identifying a first network connection to which the UE is not subscribed; identifying a fallback configuration to be applied based at least in part on the identification that the UE is not connected to the first network; determining a second network to which the UE should connect, among one or more other networks, based at least in part on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and attempting to connect to the second network based at least in part on the fallback configuration and the fact that the UE is not connected to the first network.

[0261] Aspect 2: The method of Aspect 1, wherein identifying the fallback configuration further includes: identifying a set of one or more networks to which the UE is allowed to switch when the first network is unavailable, the set of one or more networks being arranged in a list based on the priority associated with each network.

[0262] Aspect 3: The method of aspect 2, wherein determining to connect to the second network further includes: identifying a network in the set of one or more networks associated with the highest priority, the second network being associated with the highest priority; and determining to establish a connection to the second network based at least in part on the association of the second network with the highest priority.

[0263] Aspect 4: The method of any of Aspects 2 to 3, wherein determining to connect to the second network further comprises: identifying, at a first time, a network in the set of one or more networks associated with the highest priority, the second network being associated with the highest priority; and at a second time determining to establish a connection to the second network based at least in part on the association of the second network with the highest priority, the duration between the first time and the second time being randomly calculated within a configured range.

[0264] Aspect 5: The method of any of Aspects 2 to 4, wherein the UE is configured with a set of one or more networks, the set of one or more networks being included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identity Module (USIM).

[0265] Aspect 6: The method of any of Aspects 2 to 5 further includes: receiving the set of one or more networks via over-the-air (OTA) via a UE parameter update procedure or a roaming guidance procedure.

[0266] Aspect 7: The method of any of Aspects 1 to 6 further includes: determining, at least in part, based on the attempt, that the second network is currently unavailable to the UE.

[0267] Aspect 8: The method of aspect 7, wherein attempting to connect to the second network further includes: monitoring indications from the second network that the second network can be used as a fallback network when the first network is unavailable.

[0268] Aspect 9: The method of aspect 8, wherein determining that the second network is currently unavailable to the UE further includes: determining that the indication is not present in the broadcast from the second network.

[0269] Aspect 10: The method of any of Aspects 8 to 9, wherein the UE monitors the indication from the second network in the SIB.

[0270] Aspect 11: The method of any of Aspects 7 to 10, wherein determining that the second network is currently unavailable to the UE further includes: transmitting a registration message to the second network; and receiving a rejection message with a rejection reason indication from the second network in response to the registration message.

[0271] Aspect 12: The method of aspect 11, wherein the rejection message includes a backoff timer that indicates the UE to suppress the time duration of the attempt to establish a connection with the second network.

[0272] Aspect 13: The method of aspect 12 further includes: transmitting a second registration message to the second network at least in part based on the expiration of the backoff timer.

[0273] Aspect 14: The method of any of Aspects 7 to 13 further includes: at least in part based on determining that the second network is currently unusable for the UE to attempt to connect to one of the one or more other networks.

[0274] Aspect 15: A method for wireless communication at a UE, comprising: identifying a first network connection to which the UE is not subscribed; identifying a fallback configuration to be applied based at least in part on the identification that the UE is not connected to the first network; determining a second network to which the UE should connect, among one or more other networks, based at least in part on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and attempting to connect to the second network based at least in part on the fallback configuration and the fact that the UE is not connected to the first network.

[0275] Aspect 16: The method of aspect 15 further includes: receiving from the first network a notification that services for the UE will be provided by the one or more other networks via UE roaming, wherein the fallback configuration is identified as being based at least in part on the notification from the first network.

[0276] Aspect 17: The method of aspect 16, wherein the notification from the first network indicates that the first network is unavailable.

[0277] Aspect 18: The method of any of Aspects 16 to 17, wherein identifying the fallback configuration further includes: identifying a set of networks to which the UE is permitted to switch when the first network is unavailable, the set of networks being arranged in a list based on the priority associated with each network.

[0278] Aspect 19: The method of aspect 18, wherein determining to connect to the second network further includes: identifying a network in the network set associated with the highest priority, the second network being associated with the highest priority; and determining to establish a connection to the second network based at least in part on the association of the second network with the highest priority.

[0279] Aspect 20: The method of aspect 18, wherein determining to connect to the second network further includes: identifying, at a first time, a network in the network set associated with the highest priority, the second network being associated with the highest priority; and at a second time determining to establish a connection to the second network based at least in part on the association of the second network with the highest priority, the duration between the first time and the second time being randomly calculated within a configured range.

[0280] Aspect 21: The method of any of Aspects 18 to 20, wherein the UE is configured with the network set, which is included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identification Module (USIM).

[0281] Aspect 22: The method of any of Aspects 18 to 20 further includes: receiving the network set via over-the-air (OTA) via a UE parameter update procedure or a roaming guidance procedure.

[0282] Aspect 23: The method of any of Aspects 16 to 22, wherein receiving the notification from the first network further includes: receiving a deregistration message from the first network instructing the UE to deregister from the first network.

[0283] Aspect 24: The method of aspect 23, wherein the deregistration message includes a set of networks arranged in a list based on the priority associated with each network or the identifier of the network to which the UE wants to connect, and the UE determines to connect to the second network based at least in part on the deregistration message.

[0284] Aspect 25: The method of any of Aspects 15 to 17, wherein identifying the fallback configuration further includes: identifying a function for the UE to determine an access identity, the access identity being used by the UE to determine which of one or more other networks to connect to and to the determined network.

[0285] Aspect 26: The method of aspect 25 further includes: calculating a value based at least in part on the function, the value indicating an access identity in a set of access identities, wherein each network is associated with a particular access identity.

[0286] Aspect 27: The method of aspect 26 further includes: determining one or more networks associated with the access identity indicated by the calculated value; and determining, at least in part, to establish a connection with the second network based on the association of the second network with the access identity indicated by the calculated value.

[0287] Aspect 28: The method of any of Aspects 26 to 27 further includes: determining that there is no available network associated with the access identity indicated by the calculated value; and randomly determining, at least in part, to connect to the second network among the one or more other networks, based on the determination that there is no available network associated with the access identity indicated by the calculated value.

[0288] Aspect 29: A method for wireless communication at a UE, comprising: receiving from a first network to which the UE is subscribed a notification that services for the UE will be provided by one or more other networks via UE roaming; assessing the availability of a second network among the one or more other networks based at least in part on the notification from the first network; determining, at least in part on the attempt, that the second network is currently unavailable to the UE; and at least in part on the determination that the second network is currently unavailable to the UE, attempting to connect to one of the one or more other networks.

[0289] Aspect 30: The method of aspect 29, wherein assessing the availability of the second network in one or more other networks further comprises: monitoring indications from the second network that the second network may be used as a fallback network when the first network is unavailable.

[0290] Aspect 31: The method of aspect 30, wherein determining that the second network is currently unavailable to the UE further includes: determining that the indication is not present in a broadcast from the second network.

[0291] Aspect 32: The method of any of Aspects 30 to 31, wherein determining that the second network is currently unavailable to the UE further includes: transmitting a registration message to the second network; and receiving a rejection message with a rejection reason indication from the second network in response to the registration message.

[0292] Aspect 33: The method of aspect 32, wherein the rejection reason indication indicates that the UE wants to attempt to connect to a network different from the second network in one or more other networks.

[0293] Aspect 34: The method of aspect 33, wherein attempting to connect to one of the one or more other networks further comprises: attempting to connect to a third network of the one or more other networks based at least in part on the UE receiving the rejection reason indication from the second network.

[0294] Aspect 35: The method of aspect 32, wherein the rejection message includes a backoff timer that indicates the UE to suppress the time duration of the attempt to establish a connection with the second network.

[0295] Aspect 36: The method of aspect 35, wherein attempting to connect to the one of the one or more other networks further includes: transmitting a second registration message to the second network at least in part based on the expiration of the backoff timer.

[0296] Aspect 37: The method of any of Aspects 30 to 36, wherein the UE monitors the indication from the second network in the SIB.

[0297] Aspect 38: A method for wireless communication at a base station, comprising: transmitting, during a non-subscriber UE acceptance mode, an indication that a second network is available as a fallback network when a first network is unavailable, the base station serving the second network; establishing a connection with one or more UEs based at least in part on receiving a registration message from the one or more UEs in response to transmitting the indication; identifying a congestion level of the second network, wherein the identified congestion level is equal to or greater than a congestion level threshold; and switching from the non-subscriber UE acceptance mode to a non-subscriber UE rejection mode in which the base station refuses to connect to the non-subscriber UEs, the switching being based at least in part on the congestion level being equal to or greater than the congestion level threshold.

[0298] Aspect 39: The method of aspect 38, wherein identifying the congestion level of the second network further includes: receiving from the access and mobility management function (AMF) of the base station a message instructing the base station to switch to the non-subscriber UE rejection mode.

[0299] Aspect 40: The method of aspect 39, wherein the base station suppresses the transmission of the indication that the second network can be used as a fallback network.

[0300] Aspect 41: The method of aspect 39 further includes: transmitting, during the non-subscriber UE rejection mode, an indication that the second network is available as a fallback network when the first network is unavailable; receiving a registration message from the one or more UEs in response to transmitting the indication; and transmitting a rejection message with a rejection reason indication to the one or more UEs.

[0301] Aspect 42: The method of aspect 41, wherein the rejection message includes an indication that each of the one or more UEs is attempting to connect to a network different from the second network.

[0302] Aspect 43: The method of any of Aspects 41 to 42, wherein the rejection message includes a backoff timer that instructs each of the one or more UEs to suppress the time duration for which it attempts to establish a connection with the second network.

[0303] Aspect 44: The method of aspect 43 further includes: receiving a second registration message from one or more of the one or more UEs based at least in part on the expiration of the backoff timer.

[0304] Aspect 45: The method of any of Aspects 38 to 44 further includes: receiving a notification that the first network subscribed to by one or more UEs is unavailable and that the one or more UEs intend to attempt to connect to one or more other networks via roaming.

[0305] Aspect 46: The method of aspect 45, wherein the transmission of the indication during the non-subscriber UE acceptance mode is based at least in part on receiving a notification that the first network is unavailable for one or more UE subscriptions.

[0306] Aspect 47: An apparatus for wireless communication at a UE, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of any one of Aspects 1 to 14.

[0307] Aspect 48: An apparatus for wireless communication at a UE, comprising at least one means for performing the method of any one of aspects 1 to 14.

[0308] Aspect 49: A non-transient computer-readable medium storing code for wireless communication at a UE, the code including instructions executable by a processor to perform methods as described in any of Aspects 1 to 14.

[0309] Aspect 50: An apparatus for wireless communication at a UE, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of any one of aspects 15 to 28.

[0310] Aspect 51: An apparatus for wireless communication at a UE, comprising at least one means for performing the method of any one of aspects 15 to 28.

[0311] Aspect 52: A non-transient computer-readable medium storing code for wireless communication at a UE, the code including instructions executable by a processor to perform methods as described in any of Aspects 15 to 28.

[0312] Aspect 53: An apparatus for wireless communication at a UE, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of any one of aspects 29 to 37.

[0313] Aspect 54: An apparatus for wireless communication at a UE, comprising at least one means for performing the method of any one of aspects 29 to 37.

[0314] Aspect 55: A non-transient computer-readable medium storing code for wireless communication at a UE, the code including instructions executable by a processor to perform methods as described in any of Aspects 29 to 37.

[0315] Aspect 56: An apparatus for wireless communication at a base station, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method as described in any one of aspects 38 to 46.

[0316] Aspect 57: An apparatus for wireless communication at a base station, comprising at least one means for performing the method of any one of aspects 38 to 46.

[0317] Aspect 58: A non-transient computer-readable medium storing code for wireless communication at a base station, the code including instructions executable by a processor to perform methods as described in any of Aspects 38 to 46.

[0318] It should be noted that the methods described in this paper describe possible implementations, and the operations and steps can be rearranged or otherwise modified, and other implementations are also possible. Furthermore, aspects from two or more methods can be combined.

[0319] While aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for illustrative purposes, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in most of the description, the techniques described herein can also be applied to networks other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques can be applied to a variety of other wireless communication systems, such as Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0320] The information and signals described herein can be represented using any of a wide variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout this description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0321] The various illustrative boxes and components described herein can be implemented or executed using a general-purpose processor, DSP, ASIC, CPU, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternatives, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration).

[0322] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Other examples and implementations fall within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed such that different parts of the function are implemented at different physical locations.

[0323] Computer-readable media includes both non-transient computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. Non-transient storage media can be any available medium accessible to a general-purpose or special-purpose computer. By way of example and not limitation, non-transient computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transient medium that can be used to carry or store desired program code in the form of instructions or data structures and is accessible to a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Similarly, any connection is also legitimately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then that coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable media. As used in this article, disk and disc include CDs, laser discs, optical discs, DVDs, floppy disks, and Blu-ray discs, where disks often magnetically reproduce data while discs optically reproduce data using lasers. Combinations of these media are also included within the scope of computer-readable media.

[0324] As used herein (including in the claims), the word "or" in an enumeration of items (e.g., an enumeration of items accompanied by phrases such as "at least one of" or "one or more of") indicates an inclusive enumeration, such that an enumeration of at least one of, for example, A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Similarly, as used herein, the phrase "based on" should not be interpreted as referring to a closed set of conditions. For example, an example step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0325] In the accompanying drawings, similar components or features may have the same reference numerals. Furthermore, components of the same type may be distinguished by a dash following the reference numeral and a second reference numeral used to differentiate between similar components. If only the first reference numeral is used in the description, the description may apply to any of the similar components having the same first reference numeral, regardless of the second reference numeral or other subsequent reference numerals.

[0326] The descriptions herein, illustrated with reference to the accompanying drawings, depict exemplary configurations and are not representative of all examples that may be implemented or fall within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration" and does not imply "superior" or "outperforming" other examples. This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0327] The description provided herein is intended to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the universal principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for performing wireless communication at a user equipment (UE), comprising: The identifier indicates that the UE is not connected to a first network subscribed to by the UE in a region where the region is served by the first network. The fallback configuration to be applied is identified at least in part based on identifying that the UE is not connected to the first network. Identifying the fallback configuration includes identifying a set of one or more networks in the region to which the UE is allowed to switch when the first network is unavailable, wherein the UE is provided with the set of one or more networks by the first network. The second network to which the UE should connect is determined, at least in part, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and At least in part, the UE attempts to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

2. The method of claim 1, wherein the set of one or more networks is arranged in a list based on the priority associated with each network.

3. The method of claim 2, wherein determining to connect to the second network further comprises: Identify the network in the set of one or more networks that is associated with the highest priority, wherein the second network is associated with the highest priority; as well as The determination to establish a connection with the second network is based at least in part on the association between the second network and the highest priority.

4. The method of claim 2, wherein determining to connect to the second network further comprises: In the first instance, identify the network in the set of one or more networks that is associated with the highest priority, and the second network is associated with the highest priority; as well as The determination to establish a connection with the second network is made at least in part based on the association of the second network with the highest priority, and the duration between the first and second times is randomly calculated within a configured range.

5. The method of claim 2, wherein the UE is configured with a set of one or more networks, the set of one or more networks being included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identity Module (USIM).

6. The method of claim 2, further comprising: The set of one or more networks is received via over-the-air (OTA) communication through the UE parameter update procedure or roaming guidance procedure.

7. The method of claim 1, further comprising: The second network is currently unavailable to the UE, at least in part, based on the attempt.

8. The method of claim 7, wherein attempting to connect to the second network further comprises: Monitor indications from the second network that the second network can be used as a fallback network when the first network is unavailable.

9. The method of claim 8, wherein determining that the second network is currently unavailable to the UE further comprises: It was determined that the instruction was not present in the broadcast from the second network.

10. The method of claim 8, wherein the UE monitors the indication from the second network in the System Information Block (SIB).

11. The method of claim 7, wherein determining that the second network is currently unavailable to the UE further comprises: Transmit the registration message to the second network; as well as In response to the registration message, a rejection message with a rejection reason indication is received from the second network.

12. The method of claim 11, wherein the rejection message includes a backoff timer that instructs the UE to suppress the time duration for attempting to establish a connection with the second network.

13. The method of claim 12, further comprising: The second registration message is transmitted to the second network at least in part based on the expiration of the backoff timer.

14. The method of claim 7, further comprising: At least in part, this is based on the determination that the second network is currently unavailable to the UE for attempting to connect to one of the one or more other networks.

15. An apparatus for performing wireless communication at a user equipment (UE), comprising: processor; Memory coupled to the processor; as well as Instructions stored in the memory and executable by the processor to cause the device to perform the following operations: The identifier indicates that the UE is not connected to a first network subscribed to by the UE in a region where the region is served by the first network. The fallback configuration to be applied is identified at least in part based on identifying that the UE is not connected to the first network. Identifying the fallback configuration includes identifying a set of one or more networks in the region to which the UE is allowed to switch when the first network is unavailable, wherein the UE is provided with the set of one or more networks by the first network. The second network to which the UE should connect is determined, at least in part, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and At least in part, the UE attempts to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

16. The apparatus of claim 15, wherein the set of one or more networks is arranged in a list based on a priority associated with each network.

17. The apparatus of claim 16, wherein the instructions for determining to connect to the second network are further executable by the processor to cause the apparatus to: Identify the network in the set of one or more networks that is associated with the highest priority, wherein the second network is associated with the highest priority; and The determination to establish a connection with the second network is based at least in part on the association between the second network and the highest priority.

18. The apparatus of claim 16, wherein the instructions for determining to connect to the second network are further executable by the processor to cause the apparatus to: In the first instance, identify the network in the set of one or more networks associated with the highest priority, and the second network is associated with the highest priority; and The determination to establish a connection with the second network is made at least in part based on the association of the second network with the highest priority, and the duration between the first and second times is randomly calculated within a configured range.

19. The apparatus of claim 16, wherein the UE is configured with a set of one or more networks, the set of one or more networks being included in the data file of the UE's Universal Mobile Telecommunications Service (UMTS) Subscriber Identity Module (USIM).

20. The apparatus of claim 16, wherein the instructions are further executable by the processor to cause the apparatus to: The set of one or more networks is received via over-the-air (OTA) communication through the UE parameter update procedure or roaming guidance procedure.

21. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to: The second network is currently unavailable to the UE, at least in part, based on the attempt.

22. The apparatus of claim 21, wherein the instructions for attempting to connect to the second network can be further executed by the processor to cause the apparatus to: Monitor indications from the second network that the second network can be used as a fallback network when the first network is unavailable.

23. The apparatus of claim 22, wherein the instruction for determining that the second network is currently unavailable to the UE can be further executed by the processor to cause the apparatus to: It was determined that the instruction was not present in the broadcast from the second network.

24. The apparatus of claim 22, wherein: The UE monitors the indication from the second network in the System Information Block (SIB).

25. The apparatus of claim 21, wherein the instruction for determining that the second network is currently unavailable to the UE can be further executed by the processor to cause the apparatus to: Transmitting registration messages to the second network; and In response to the registration message, a rejection message with a rejection reason indication is received from the second network.

26. The apparatus of claim 25, wherein the rejection message includes a backoff timer that instructs the UE to suppress the time duration for which it attempts to establish a connection with the second network.

27. The apparatus of claim 26, wherein the instructions are further executable by the processor to cause the apparatus to: The second registration message is transmitted to the second network at least in part based on the expiration of the backoff timer.

28. The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to: At least in part, this is based on the determination that the second network is currently unavailable to the UE for attempting to connect to one of the one or more other networks.

29. An apparatus for performing wireless communication at a user equipment (UE), comprising: A means for identifying a region where the UE is not connected to a first network to which the UE has subscribed, the region being served by the first network; A means for identifying a fallback configuration to be applied based at least in part on identifying that the UE is not connected to the first network, the identification of the fallback configuration including: identifying a set of one or more networks in the region to which the UE is allowed to switch when the first network is unavailable, wherein the UE is provided with the set of one or more networks by the first network; Means for determining, at least in part, a second network to which the UE should connect, in one or more other networks, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and A means for attempting to connect to the second network based at least in part on the fallback configuration and the fact that the UE is not connected to the first network.

30. A non-transient computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to perform the following operations: The identifier indicates that the UE is not connected to a first network subscribed to by the UE in a region where the region is served by the first network. The fallback configuration to be applied is identified at least in part based on identifying that the UE is not connected to the first network. Identifying the fallback configuration includes identifying a set of one or more networks in the region to which the UE is allowed to switch when the first network is unavailable, wherein the UE is provided with the set of one or more networks by the first network. The second network to which the UE should connect is determined, at least in part, based on the fallback configuration, wherein the UE lacks a subscription to any of the one or more other networks; and At least in part, the UE attempts to connect to the second network based on the fallback configuration and the fact that the UE is not connected to the first network.

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