WO2021223220A1

WO2021223220A1 - Recovery from ps call failure caused by network release of rrc connections on dual 5gnr subscription wireless devices

Info

Publication number: WO2021223220A1
Application number: PCT/CN2020/089210
Authority: WO
Inventors: Jian Li; Hao Zhang; Fojian ZHANG; Chaofeng HUI; Yi Liu; Yuankun ZHU; Miao Fu; Yongrui PENG; Shuhong Wang
Original assignee: Qualcomm Incorporated
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2021-11-11

Abstract

Embodiments include systems and methods for recovering from packet switched (PS) call failure in a fifth generation (5G) non-standalone (NSA) network. Various aspects may enable recovery from PS call failure caused by network release of RRC connections on dual 5G new radio (5GNR) subscription wireless devices. Various embodiments may include sending a fourth generation (4G) fallback synchronization indication from a first 5GNR subscription to a second 5GNR subscription in response to determining that a total number of RRC connection releases received from a base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value.

Description

Recovery From PS Call Failure Caused By Network Release Of RRC Connections On Dual 5GNR Subscription Wireless Devices

BACKGROUND

Long Term Evolution (LTE) , Fifth Generation (5G) new radio (NR) (5GNR) , and other recently developed communication technologies allow wireless devices to communicate information at data rates (e.g., in terms of Gigabits per second, etc. ) that are orders of magnitude greater than what was available just a few years ago. Today’s communication networks are also more secure, resilient to multipath fading, allow for lower network traffic latencies, and provide better communication efficiencies (e.g., in terms of bits per second per unit of bandwidth used, etc. ) . These and other recent improvements have facilitated the emergence of the Internet of Things (IOT) , large scale Machine to Machine (M2M) communication systems, autonomous vehicles, and other technologies that rely on consistent and secure communications.

Multi-subscriber identity module (SIM) wireless devices have become increasingly popular because of the versatility that such devices provide. For example, a multi-SIM multi-standby (MSMS) wireless device enables at least two SIMs to be in idle mode waiting to begin communications, but only allows one SIM at a time to participate in an active communication due to sharing of a single radio frequency (RF) resource (e.g., a wireless transceiver) . As another example, multi-SIM multi-active (MSMA) wireless devices enable at least two SIMs to be in idle mode waiting to being communications, and allows at least two SIMS to participate in active communication using at least two RF resources (e.g., two wireless transceivers) .

One implementation option for 5G networks being adopted is a 5G non-standalone (NSA) network in which a radio access network (RAN) providing both LTE and NR support (e.g., a RAN including both LTE base stations, such as LTE Evolved nodeBs (eNodeBs or eNBs) , and NR base stations, such as Next Generation NodeB (gNodeBs or gNBs) ) are connected to an LTE core network (e.g., an Evolved Packet Core (EPC) network) . A wireless device in such 5G NSA networks that can support both LTE and NR communications can signal to the 5G NSA that the wireless device supports dual connectivity with new radio (DCNR) . In such 5G NSA networks, a packet switched (PS) call failure on a wireless device indicating support for DCNR can sometimes be unrecoverable and can sometimes result in all subsequent PS service setup attempts failing, thereby preventing data traffic communications. Such PS call failure on a wireless device indicating support for DCNR can result in a negative user experience as data services, such as Internet access, etc., can be unavailable for a period of time.

SUMMARY

Various aspects include systems and methods for recovering from packet switched (PS) call failure in a fifth generation (5G) non-standalone (NSA) network. Various aspects may enable recovery from a PS call failure caused by network release of RRC connections on dual 5G new radio (5GNR) subscription wireless devices. Various aspects may be performed by a processor of a multi-subscriber identity module (SIM) wireless device configured with a first 5GNR subscription and a second 5GNR subscription. Various aspects may include determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G NSA network, determining whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value in response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to the same base station of the 5G NSA network, and, in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value, triggering fourth generation (4G) fallback for the first 5GNR subscription, and sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription. In some aspects, the first 5GNR subscription and the second 5GNR subscription may be associated with a same network operator.

Some aspects may further include sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription, receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network, sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network, and receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.

Some aspects may further include setting a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription, determining whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in response to receiving a RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription, sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled, receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network, sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network, and receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.

In some aspects, triggering 4G fallback for the first 5GNR subscription may include determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription, sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription, receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network, sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network, and receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network. In some aspects, the time period may be one hour and the trigger value may be four.

In some aspects, triggering 4G fallback for the first 5GNR subscription may include sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription, receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network, sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network, and receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network. In some aspects, the time period may be one hour and the trigger value may be five.

Further aspects include a wireless device having a processor configured to perform one or more operations of any of the methods summarized above. Further aspects include a non-transitory processor-readable storage medium having stored thereon processor-executable instructions configured to cause a processor of a wireless device to perform operations of any of the methods summarized above. Further aspects include a wireless device having means for performing functions of any of the methods summarized above. Further aspects include a system-on-chip for use in a wireless device that includes a processor configured to perform one or more operations of any of the methods summarized above. Further aspects include a system in a package that includes two systems on chip for use in a wireless device that includes a processor configured to perform one or more operations of any of the methods summarized above.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the claims, and together with the general description given above and the detailed description given below, serve to explain the features of the claims.

FIG. 1 is a system block diagram illustrating an example communication system suitable for implementing any of the various embodiments.

FIG. 2 is a component block diagram illustrating an example computing and wireless modem system suitable for implementing any of the various embodiments.

FIG. 3 is a component block diagram illustrating a software architecture including a radio protocol stack for the user and control planes in wireless communications suitable for implementing any of the various embodiments.

FIG. 4 is a component block diagram illustrating a system configured for wireless communication in accordance with various embodiments.

FIG. 5A is a process flow diagram illustrating a method for recovering from packet switched (PS) call failure in a fifth generation (5G) non-standalone (NSA) network in accordance with various embodiments.

FIG. 5B is a process flow diagram illustrating a method for recovering from PS call failure in a 5G NSA network in accordance with various embodiments.

FIG. 5C is a process flow diagram illustrating a method for recovering from PS call failure in a 5G NSA network in accordance with various embodiments.

FIG. 5D is a process flow diagram illustrating a method for triggering fourth generation (4G) fallback in accordance with various embodiments.

FIG. 5E is a process flow diagram illustrating a method for triggering 4G fallback in accordance with various embodiments.

FIG. 6A is a call flow diagram illustrating example interactions between two 5G new radio (5GNR) subscriptions of a wireless device and a same base station of a 5G NSA network in accordance with various embodiments.

FIG. 6B is a call flow diagram illustrating example interactions between two

5GNR subscriptions of a wireless device and a same base station of a 5G NSA network in accordance with various embodiments.

FIG. 7 is a component block diagram of a network computing device suitable for use with various embodiments.

FIG. 8 is a component block diagram of a wireless device suitable for use with various embodiments.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and embodiments are for illustrative purposes, and are not intended to limit the scope of the claims.

Various embodiments include systems and methods for recovering from packet switched (PS) call failure in a fifth generation (5G) non-standalone (NSA) network. Various embodiments may enable wireless recovery from PS call failure caused by network release of RRC connections on dual 5G new radio (5GNR) subscription wireless devices. Various embodiments may include sending a fourth generation (4G) fallback synchronizations indication from a first 5GNR subscription of a multi-subscriber identity module (SIM) wireless device to a second 5GNR subscription of the multi-SIM wireless device. In various embodiments, based at least in part on the 4G fallback synchronization, the second 5GNR subscription may detach and reattach to a base station of a 5G NSA network indicating dual connectivity with new radio (DCNR) is not supported. Reattaching to the base station of the 5G NSA network while indicating DCNR is not supported may enable PS calls to be established successfully by the second 5GNR subscription.

Various embodiments may improve user experience by enabling recovery from PS call failure and thereby allowing data traffic communications between a wireless device and the NSA network. Various embodiments may improve user experience by making data services, such as Internet access, etc., available to a user after a PS call failure. Various embodiments may save time in establishing PS calls on the second 5GNR subscription as network issues, such as repeated RRC connection releases from a base station of the 5G NSA network, experienced by the first 5GNR subscription may be avoided by the second 5GNR subscription reattaching to the base station of the 5G NSA network while indicating DCNR is not supported. Various embodiments may reduce power consumption of wireless devices establishing PS calls on the second 5GNR subscription as power consumption caused by repeated RRC connection reattempts with a base station of the 5G NSA network that was associated with network issues experienced by the first 5GNR subscription may be avoided by the second 5GNR subscription reattaching to the base station of the 5G NSA network while indicating DCNR is not supported.

The term “wireless device” is used herein to refer to any one or all of cellular telephones, smartphones, portable computing devices, personal or mobile multi-media players, laptop computers, tablet computers, smartbooks, ultrabooks, palmtop computers, wireless electronic mail receivers, multimedia Internet-enabled cellular telephones, wireless router devices, wireless appliances, medical devices and equipment, biometric sensors/devices, wearable devices including smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart rings, smart bracelets, etc. ) , entertainment devices (e.g., wireless gaming controllers, music and video players, satellite radios, etc. ) , wireless-network enabled Internet of Things (IoT) devices including smart meters/sensors, industrial manufacturing equipment, large and small machinery and appliances for home or enterprise use, wireless communication elements within autonomous and semiautonomous vehicles, wireless devices affixed to or incorporated into various mobile platforms, global positioning system devices, and similar electronic devices that include a memory, multiple SIMs, wireless communication components and a programmable processor.

The term “system-on-chip” (SOC) is used herein to refer to a single integrated circuit (IC) chip that contains multiple resources and/or processors integrated on a single substrate. A single SOC may contain circuitry for digital, analog, mixed-signal, and radio-frequency functions. A single SOC may also include any number of general purpose and/or specialized processors (digital signal processors, modem processors, video processors, etc. ) , memory blocks (e.g., ROM, RAM, Flash, etc. ) , and resources (e.g., timers, voltage regulators, oscillators, etc. ) . SOCs may also include software for controlling the integrated resources and processors, as well as for controlling peripheral devices.

The term “system in a package” (SIP) may be used herein to refer to a single module or package that contains multiple resources, computational units, cores and/or processors on two or more IC chips, substrates, or SOCs. For example, a SIP may include a single substrate on which multiple IC chips or semiconductor dies are stacked in a vertical configuration. Similarly, the SIP may include one or more multi-chip modules (MCMs) on which multiple ICs or semiconductor dies are packaged into a unifying substrate. A SIP may also include multiple independent SOCs coupled together via high speed communication circuitry and packaged in close proximity, such as on a single motherboard or in a single wireless device. The proximity of the SOCs facilitates high speed communications and the sharing of memory and resources.

As used herein, the terms “SIM, ” “SIM card, ” and “subscriber identity module” may interchangeably refer to a memory that may be an integrated circuit or embedded into a removable card, and that stores an International Mobile Subscriber Identity (IMSI) , related key, and/or other information used to identify and/or authenticate a wireless device on a network and enable a communication service with the network. Examples of SIMs include the Universal Subscriber Identity Module (USIM) provided for in the Long Term Evolution (LTE) 3GPP standard, and the Removable User Identity Module (R-UIM) provided for in the 3GPP2 standard. Universal Integrated Circuit Card (UICC) is another term for SIM. Moreover, a SIM may also refer to a virtual SIM (VSIM) , which may be implemented as a remote SIM profile loaded in an application on a wireless device, and enabling normal SIM functions on the wireless device.

Because the information stored in a SIM enables the wireless device to establish a communication link for a particular communication service or services with a particular network, the term “SIM” is also be used herein as a shorthand reference to the communication service associated with and enabled by the information stored in a particular SIM as the SIM and the communication network, as well as the services and subscriptions supported by that network, correlate to one another. Similarly, the term SIM may also be used as a shorthand reference to the protocol stack and/or modem stack and communication processes used in establishing and conducting communication services with subscriptions and networks enabled by the information stored in a particular SIM.

As used herein, the terms “multi-SIM wireless device” , “MS wireless device” , “dual-SIM wireless device” , and “DS wireless device” may interchangeably describe a wireless device that is configured with more than one SIM. Examples of multi-SIM wireless devices include multi-SIM multi-standby (MSMS) wireless devices, such as Dual-SIM (DS) dual-standby (DSDS) wireless devices, etc., and multi-SIM multi-active (MSMA) wireless devices, such as Dual-SIM dual-active (DSDA wireless devices, etc. A MSMS wireless device may be a wireless device that is configured with more than one SIM and allows idle-mode operations to be performed on two subscriptions simultaneously, as well as selective communication on one subscription while performing idle-mode operations on at least one other subscription. A MSMA wireless device may be a wireless device that is configured with more than one SIM and allows idle-mode and/or active mode operations to be performed on two subscriptions simultaneously using at least two different RF resources (e.g., two different wireless transceivers) .

As used herein, the terms “network, ” “system, ” “wireless network, ” “cellular network, ” and “wireless communication network” may interchangeably refer to a portion or all of a wireless network of a carrier associated with a wireless device and/or subscription on a wireless device. The techniques described herein may be used for various wireless communication networks, such as Code Division Multiple Access (CDMA) , time division multiple access (TDMA) , FDMA, orthogonal FDMA (OFDMA) , single carrier FDMA (SC-FDMA) and other networks. In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support at least one radio access technology, which may operate on one or more frequency or range of frequencies. For example, a CDMA network may implement Universal Terrestrial Radio Access (UTRA) (including Wideband Code Division Multiple Access (WCDMA) standards) , CDMA2000 (including IS-2000, IS-95 and/or IS-856 standards) , etc. In another example, a TDMA network may implement GSM Enhanced Data rates for GSM Evolution (EDGE) . In another example, an OFDMA network may implement Evolved UTRA (E-UTRA) (including LTE standards) , IEEE 802.11 (WiFi) , IEEE 802.16 (WiMAX) , IEEE 802.20,

etc. Reference may be made to wireless networks that use LTE standards, and therefore the terms “Evolved Universal Terrestrial Radio Access, ” “E-UTRAN” and “eNodeB” may also be used interchangeably herein to refer to a wireless network. However, such references are provided merely as examples, and are not intended to exclude wireless networks that use other communication standards.

The terms “network operator, ” “operator, ” “mobile network operator, ” “carrier, ” and “service provider” are used interchangeably herein to describe a provider of wireless communications services that owns or controls elements to sell and deliver communication services to an end user, and provides necessary provisioning and credentials as policies implemented in user device subscriptions.

As used herein, the term “RF resource” refers to the components in a communication device that send, receive, and decode radio frequency signals. An RF resource typically includes a number of components coupled together that transmit RF signals that are referred to as a “transmit chain, ” and a number of components coupled together that receive and process RF signals that are referred to as a “receive chain. ”

Modern wireless devices may now include a plurality of SIM cards that enable a user to connect to different mobile networks with the same wireless device. The plurality of SIM cards may enable the wireless device to communicate with the same base station of a wireless network using two different subscriptions. As an example, the wireless device may communicate with a base station of a 5G NSA network using information stored in a first 5GNR SIM associated with a first 5GNR subscription and that same base station of the 5G NSA network using information stored in a second 5GNR SIM associated with a second 5GNR subscription. Each SIM card stores information that serves to identify and authenticate a subscriber using a particular wireless device, and each SIM card is associated with only one subscription. For example, a SIM card may be associated with a subscription to one of a GSM, TD-SCDMA, CDMA2000, and/or WCDMA system. Further, multi-SIM operations may be applicable to any of a number of wireless communication systems, using various multiple access schemes, such as, but not limited to, CDMA, FDMA, OFDMA, or TDMA. Each SIM in a wireless device is configured with its own mobile subscription identification number (MSIN) (also called the mobile identification number (MIN) , and/or mobile station identification (MSID) ) , which is the 10-digit unique number that the wireless carrier uses to identify the wireless device. In some implementations, two or more 5GNR SIMs and their respective 5GNR subscriptions on a multi-SIM wireless device may each be associated with a same network operator. As one example, in a multi-SIM wireless device a first 5GNR SIM associated with a first 5GNR subscription and a second 5GNR SIM associated with a second 5GNR subscription may both be associated with the same network operator to support provisioning different services to the multi-SIM wireless device for each 5GNR subscription.

LTE is a mobile network standard for 4G wireless communication of high-speed data developed by the 3GPP (3rd Generation Partnership Project) and specified in its Release 8 document series. In contrast to the circuit-switched (CS) model of cellular network standards, LTE has been designed to support only packet switched (PS) services. Data services in LTE may be provided over the Internet, while multimedia services may be supported by the Internet Multimedia Subsystem (IMS) framework. The LTE standard is based on the evolution of the Universal Mobile Telecommunications System (UMTS) radio access through the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) . The E-UTRAN together with the Evolved Packet Core (EPC) network (core network accommodating LTE) make up an Evolved Packet System (EPS) . While the access network in UMTS emulates a circuit-switched connection for real time services and a packet-switched connection for datacom services, the Evolved Packet System (EPS) is purely Internet Protocol (IP) based, and both real time services and datacom services are carried by the IP protocol.

The 5G system is an advanced technology from 4G LTE, and provides a new radio access technology (RAT) through the evolution of the existing mobile communication network structure. A 5G system may support, for example, extended LTE (eLTE) as well as non-3GPP access (e.g., WLAN) .

One implementation option for 5G systems or networks currently being adopted is a 5G NSA network in which a radio access network (RAN) providing both LTE (also referred to as 4G) and NR (also referred to a 5G) support (e.g., a RAN including both LTE base stations, such as LTE Evolved nodeBs (eNodeBs or eNBs) , and NR base stations, such as Next Generation NodeB (gNodeBs or gNBs) ) is connected to an LTE core network (e.g., an Evolved Packet Core (EPC) network) . A wireless device in such 5G NSA networks that can support both LTE and NR communications can signal to the 5G NSA that the wireless device supports dual connectivity with new radio (DCNR) . In some implementations the signaling to the 5G NSA network may be on a per-subscription basis. As one example, in a multi-SIM wireless device a first 5GNR SIM associated with a first 5GNR subscription and a second 5GNR SIM associated with a second 5GNR subscription may both be associated with the same network operator to support provisioning different services to the multi-SIM wireless device for each 5GNR subscription may both signal to the 5G NSA that each respective 5GNR subscription supports DCNR.

In 5G NSA networks, different data traffic may exist for different services. For example, conventional IP-oriented (i.e., “data-centric” ) applications (e.g. web-browsers, games, e-mail applications, etc. ) , may be provided in an LTE and/or 5G system as data services over the public Internet. Real-time communication services (e.g., voice calls, Short Message Service (SMS) communications, etc. ) may be provided in an LTE and/or 5G system as IMS services. The IMS architecture allows operators to offer carrier grade services to be offered on packet-switched networks. Examples of services that have been standardized on top of IMS include Open Mobile Alliance (OMA) presence and group list management, Push-to-Talk over Cellular (PoC) , Instant Messaging, and TISPAN/3GPP multimedia telephony for IMS (MMTel) . Other IMS services that have been developed for deployment as next-generation LTE services include Voice over LTE (VoLTE) and Video Telephony (VT) . Thus, although LTE and 5G data is IP-based, the multiple data types/services may be accessed through different packet data networks (PDN) in the 5G NSA network.

In current 5G NSA networks, a PS call failure on a wireless device indicating support for DCNR can sometimes be unrecoverable resulting in all subsequent PS service setup attempts failing, thereby preventing data traffic communications (also referred to as data-centric services) . Such PS call failures on a wireless device indicating support for DCNR can result in a negative user experience as data services, such as Internet access, can be unavailable for a period of time. When PS call failure is caused by network issues, such as network caused releases of RRC connections, those network issues may impact multiple 5GNR subscriptions indicating support for DCNR on a multi-SIM wireless device can often result in PS call failure on multiple 5GNR subscriptions, especially when the multiple 5GNR subscriptions may be associated with the same network operator as the multiple 5GNR subscriptions may be camped on the same serving base station (e.g., the same eNB) . The multiple 5GNR subscriptions may camp on the same serving base station due to various reasons, such as cell selection criteria for each 5GNR subscription resulting in the same base station being selected, the base station being an only available base station, etc.

For example, in some current 5G NSA networks, multi-SIM wireless device may register a first 5GNR subscription and a second 5GNR subscription with a same base station of the 5G NSA network. Each 5GNR subscription may initially indicate that 5GNR subscription has a 5G data capability. As specific example, each 5GNR subscription may send an attach request (ATTACH_REQ) /tracking area update request (TRACKING_AREA_UPDATE_REQ) indicating DCNR is supported by that respective 5GNR subscription. For example, a DCNR support flag bit may be set (e.g., DCNR = 1) in the attach request/tracking area update request sent to a base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , by the first 5GNR subscription and a DCNR support flag bit may be set (e.g., DCNR = 1) in the attach request/tracking area update request sent to that same base station of the 5G NSA network by the second 5GNR subscription. The base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may return an attachment acceptance (ATTACH_ACCEPT) /tracking area update acceptance (TRACKING_AREA_UPDATE_ACCEPT) to each of the respective attached 5GNR subscriptions of the multi-SIM wireless device.

In some current 5G NSA networks, one of the 5GNR subscriptions of the multi-SIM wireless device may send a service request, such as a RRC connection establishment request (RRC_CONNECTION_EST_REQ) , for data traffic (e.g., data traffic associated with an Internet browser, social media application, etc. ) to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , after attaching to the base station and indicating DCNR support. In this manner, that 5GNR subscription can attempt to establish a data call (i.e., a PS call) with the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , to send/receive the data traffic.

In some current 5G NSA networks, following the data service request, such as the RRC connection establishment request (RRC_CONNECTION_EST_REQ) , by one of the 5GNR subscriptions of the multi-SIM wireless device, the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , may respond with a RRC connection release (RRC_CONNECTION_REL) . The RRC connection release (RRC_CONNECTION_REL) may cause the 5GNR subscription to fail to establish a PS call with the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

In some current 5G NSA networks, in response to RRC connection release (RRC_CONNECTION_REL) and failure to establish a PS call, the 5GNR subscription of the multi-SIM wireless device may reattempt to establish a data call (i.e., a PS call) with the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) . For example, the 5GNR subscription of the multi-SIM wireless device may send further RRC connection establishment requests (RRC_CONNECTION_EST_REQs) to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) . In some current 5G NSA networks, the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may send RRC connection releases (RRC_CONNECTION_RELs) following each further RRC connection establishment request (RRC_CONNECTION_EST_REQ) by the 5GNR subscription of the multi-SIM wireless device, thereby causing each PS call service request by that 5GNR subscription to fail and the wireless device to be unable to recover from PS call failure (or establish a PS call) on that 5GNR subscription. This repeated failure of the 5GNR subscription to establish a PS call, and resulting repeated failure to support data traffic, causes a degraded user experience as users are unable to access the Internet, often for a long period of time.

Various embodiments may provide a solution to the repeated failure of a 5GNR subscription to establish a PS call after attaching to the base station and indicating DCNR support by triggering fallback to a fourth generation (4G) mode for that 5GNR subscription. In various embodiments, a processor of a multi-SIM wireless device (e.g., application processor, modem processor, etc. ) may determine whether both a first 5GNR subscription and a second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G NSA network, such as a same LTE cell (e.g., an eNB) . When two 5GNR subscriptions may be attached to the same base station of a 5G NSA network, especially when the two 5GNR subscriptions may both be associated with a same network operator, network issues impacting the first 5GNR subscription may impact the second 5GNR subscription. Various embodiments enable proactive triggering of fallback to a 4G mode on the second 5GNR subscription when the first 5GNR subscription is already impacted by network issues, such as repeated RRC connection releases, without waiting for the second subscription to fully experience the same network issues, such as repeated RRC connection releases. In various embodiments, fallback to a 4G mode for a 5GNR subscription may include detaching the 5GNR subscription from a base station of a 5G NSA network, such as a same LTE cell (e.g., an eNB) , and reattaching the 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

In various embodiments, in response to determining that both a first 5GNR subscription and a second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network, such as a same LTE cell (e.g., an eNB) , a processor of a mulit-SIM wireless device (e.g., application processor, modem processor, etc. ) may determine whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value. The processor of the wireless device (e.g., an application processor (AP) , modem processor, etc. ) may maintain a counter to record the number of RRC connection releases (RRC_CONNECTION_RELs) received for a subscription from a 5G NSA network (e.g., RRC connection releases received for a first 5GNR subscription from a 5G NSA network, RRC connection releases received for a second 5GNR subscription from a 5G NSA network, etc. ) . The counter reaching a trigger value may indicate that the 5G NSA network is operating abnormally and PS call failure may be occurring or likely to occur. In some embodiments, the counter may track the total number of RRC connection releases (RRC_CONNECTION_RELs) received requests received during a time period. As one example, the time period may be one hour and the trigger value may be four RRC connection releases (RRC_CONNECTION_RELs) . As another example, the time period may be one hour and the trigger value may be five RRC connection releases (RRC_CONNECTION_RELs) . In some embodiments, the trigger value may be set to a maximum value (e.g., a maximum counter value (MAX_COUNTER) ) of RRC connection releases (RRC_CONNECTION_RELs) the first 5GNR subscription is to experience in the time period before triggering fallback to 4G on the first 5GNR subscription itself. For example, the maximum counter value (MAX_COUNTER) and trigger value may both be the same value, such as five. In some embodiments, the trigger value may be set to less than the maximum counter value (MAX_COUNTER) of RRC connection releases (RRC_CONNECTION_RELs) the first 5GNR subscription is to experience in the time period before triggering fallback to 4G on the first 5GNR subscription itself. For example, the trigger value maybe one less than the maximum counter value (MAX_COUNTER) . As a specific example, the trigger value may be four and the maximum counter value may be five. In this manner, the trigger value may be reached prior a sufficient number of RRC connection releases (RRC_CONNECTION_RELs) being experienced by the first 5GNR subscription (e.g., before the maximum counter value (MAX_COUNTER) value is reached) .

In some embodiments, as RRC connection releases (RRC_CONNECTION_RELs) are received, indications of the RRC connection releases (RRC_CONNECTION_RELs) may be stored. The indications of the RRC connection releases (RRC_CONNECTION_RELs) may include timestamps of when the RRC connection releases (RRC_CONNECTION_RELs) were received. The time period, such as one hour, may extend backward from the most recent received RRC connection release (RRC_CONNECTION_REL) . The counter may track the number of RRC connection release (RRC_CONNECTION_REL) indications having timestamps falling in the time window corresponding to the time period, such as the total number of RRC connection releases (RRC_CONNECTION_RELs) received in the one hour prior to the most recent RRC connection release (RRC_CONNECTION_REL) . In some embodiments, a counter and timer combination may be used to track the total number of RRC connection releases (RRC_CONNECTION_RELs) received in a time period. For example, the counter may track a total number of RRC connection releases (RRC_CONNECTION_RELs) received from a base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for a specific subscription (e.g., the first 5GNR subscription) during a time period tracked by the timer, and the counter may be reset at each expiration of the timer.

In various embodiments, in response to determining that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for the first 5GNR subscription during the time period exceeds the trigger value, a processor of a wireless device (e.g., AP, modem processor, etc. ) may send a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription. The 4G fallback synchronization indication may be a message, interrupt, flag bit setting, or other type indication provided to the second 5GNR subscription. In some embodiments, in response to determining that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for the first 5GNR subscription during the time period exceeds the trigger value, a processor of a wireless device (e.g., AP, modem processor, etc. ) may trigger 4G fallback for the first 5GNR subscription. In some embodiments, triggering of 4G fallback for the first 5GNR subscription may occur prior to sending a 4G fallback synchronization indication to the second 5GNR subscription. In some embodiments, triggering of 4G fallback for the first 5GNR subscription may occur concurrently with sending a 4G fallback synchronization indication to the second 5GNR subscription. In some embodiments, triggering of 4G fallback for the first 5GNR subscription may occur after sending a 4G fallback synchronization indication to the second 5GNR subscription.

In various embodiments, in response to receiving the 4G fallback synchronization request from the first 5GNR subscription, the processor of the multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may initiate fallback to a 4G mode including detaching the 5GNR subscription from the base station of a 5G NSA network, such as a LTE cell (e.g., an eNB) , and reattaching the second 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

In various embodiments, in response to receiving the 4G fallback synchronization request from the first 5GNR subscription, a processor of a multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may set a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode is enabled. A 4G synchronization flag may be a memory structure, such as a flag bit, the setting state of which may indicate whether or not a 4G fallback synchronization request from the first 5GNR subscription was received. For example, a setting of a 4G synchronization flag (e.g., 4G synch bit = 1) may indicate a 4G fallback synchronization request from the first 5GNR subscription was received and an unsetting of a 4G synchronization flag (e.g., 4G synch bit = 0) may indicate a 4G fallback synchronization request from the first 5GNR subscription was not received. In some embodiments, the setting of the state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode is enabled may support the signaling of potential network issues being experienced by the first 5GNR subscription to the second 5GNR subscription without immediately triggering the second 5GNR subscription to initiate fallback to a 4G mode. The delay of triggering the second 5GNR subscription to initiate fallback to a 4G mode may enable the second 5GNR subscription to attempt at least one additional RRC connection establishment request (RRC_CONNECTION_EST_REQ) of its own with the same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , that was causing actual or potential network issues, such as repeated RRC connection releases (RRC_CONNECTION_RELs) , for the first 5GNR subscription.

In some embodiments, in response to receiving a RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription, a processor of a multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may determine whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled. The state of the 4G synchronization flag for the second 5GNR subscription may control whether fallback to a 4G mode is to be triggered or not for the second 5GNR subscription in response to receiving a RRC connection release (RRC_CONNECTION_REL) for the second 5GNR subscription. In response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled, a processor of a multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may initiate fallback to a 4G mode including detaching the 5GNR subscription from the base station of a 5G NSA network, such as a LTE cell (e.g., an eNB) , and reattaching the second 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

In some embodiments, triggering 4G fallback for the first 5GNR subscription may include performing operations to fallback to a 4G mode for the first 5GNR subscription. 4G fallback may include detaching the first 5GNR subscription from the base station of a 5G NSA network, such as a LTE cell (e.g., an eNB) , and reattaching the first 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. In some embodiments, a processor of a multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may trigger fallback to a 4G mode in response to determining that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for the first 5GNR subscription during the time period exceeds the trigger value, a processor of a wireless device (e.g., AP, modem processor, etc. ) . For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , to trigger fallback to a 4G mode in response to determining that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network (e.g., an LTE cell or an eNB) for the first 5GNR subscription during the time period exceeds the trigger value. For example, such initiation of fallback to a 4G mode on the first 5GNR subscription may occur when the maximum counter value (MAX_COUNTER) and trigger value may both be the same value, such as five. In this manner, both the first 5GNR subscription and the second 5GNR subscription may reattach to the same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , indicating DCNR is not supported.

In some embodiments, a processor of a multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may trigger 4G fallback for the first 5GNR subscription by determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription. For example, the processor may determine whether at least one additional RRC connection release is received from the same base station of the 5GNS network for the first 5GNR subscription in response to determining that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for the first 5GNR subscription during the time period exceeds the trigger valued. Determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription may enable the first 5GNR subscription to make at least one further attempt at establishing a PS call with DCNR supported. For example, such attempt of at least one more RRC connection establishment by the first 5GNR subscription may occur when the trigger value is one less than the maximum counter value (MAX_COUNTER) , such as the trigger value being four and the maximum counter value (MAX_COUNTER) being five. In response to determining that at least one additional RRC connection release (RRC_CONNECTION_REL) is received from the same base station of the 5G NSA network for the first 5GNR subscription, the processor of the multi-SIM wireless device (e.g., an AP, modem processor, etc. ) may initiate fallback to a 4G mode including detaching the first 5GNR subscription from the base station of a 5G NSA network, such as a LTE cell (e.g., an eNB) , and reattaching the first 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

FIG. 1 is a system block diagram illustrating an example communication system 100 suitable for implementing any of the various embodiments. The communications system 100 may be a 5G New Radio (NR) network, or any other suitable network such as an LTE network, 5G NSA network, etc.

The communications system 100 may include a heterogeneous network architecture that includes a core network 140 and a variety of mobile devices (illustrated as wireless device 120a-120e in FIG. 1) . The communications system 100 may also include a number of base stations (illustrated as the BS 110a, the BS 110b, the BS 110c, and the BS 110d) and other network entities. A base station is an entity that communicates with wireless devices, and also may be referred to as a Node B, an LTE Evolved nodeB (eNodeB or eNB) , an access point (AP) , a Radio head, a transmit receive point (TRP) , a New Radio base station (NR BS) , a 5G NodeB (NB) , a Next Generation NodeB (gNodeB or gNB) , or the like. Each base station may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a base station, a base station Subsystem serving this coverage area, or a combination thereof, depending on the context in which the term is used. The core network 140 may be any type core network, such as an LTE core network (e.g., an EPC network) , 5G core network, etc.

A base station 110a-110d may provide communication coverage for a macro cell, a pico cell, a femto cell, another type of cell, or a combination thereof. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by mobile devices with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by mobile devices with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by mobile devices having association with the femto cell (for example, mobile devices in a closed subscriber group (CSG) ) . A base station for a macro cell may be referred to as a macro BS. A base station for a pico cell may be referred to as a pico BS. A base station for a femto cell may be referred to as a femto BS or a home BS. In the example illustrated in FIG. 1, a base station 110a may be a macro BS for a macro cell 102a, a base station 110b may be a pico BS for a pico cell 102b, and a base station 110c may be a femto BS for a femto cell 102c. A base station 110a-110d may support one or multiple (for example, three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some examples, a cell may not be stationary, and the geographic area of the cell may move according to the location of a mobile base station. In some examples, the base stations 110a-110d may be interconnected to one another as well as to one or more other base stations or network nodes (not illustrated) in the communications system 100 through various types of backhaul interfaces, such as a direct physical connection, a virtual network, or a combination thereof using any suitable transport network

The base station 110a-110d may communicate with the core network 140 over a wired or wireless communication link 126. The wireless device 120a-120e may communicate with the base station 110a-110d over a wireless communication link 122.

The wired communication link 126 may use a variety of wired networks (e.g., Ethernet, TV cable, telephony, fiber optic and other forms of physical network connections) that may use one or more wired communication protocols, such as Ethernet, Point-To-Point protocol, High-Level Data Link Control (HDLC) , Advanced Data Communication Control Protocol (ADCCP) , and Transmission Control Protocol/Internet Protocol (TCP/IP) .

The communications system 100 also may include relay stations (e.g., relay BS 110d) . A relay station is an entity that can receive a transmission of data from an upstream station (for example, a base station or a mobile device) and transmit the data to a downstream station (for example, a wireless device or a base station) . A relay station also may be a mobile device that can relay transmissions for other wireless devices. In the example illustrated in FIG. 1, a relay station 110d may communicate with macro the base station 110a and the wireless device 120d in order to facilitate communication between the base station 110a and the wireless device 120d. A relay station also may be referred to as a relay base station, a relay base station, a relay, etc.

The communications system 100 may be a heterogeneous network that includes base stations of different types, for example, macro base stations, pico base stations, femto base stations, relay base stations, etc. These different types of base stations may have different transmit power levels, different coverage areas, and different impacts on interference in communications system 100. For example, macro base stations may have a high transmit power level (for example, 5 to 40 Watts) whereas pico base stations, femto base stations, and relay base stations may have lower transmit power levels (for example, 0.1 to 2 Watts) .

A network controller 130 may couple to a set of base stations and may provide coordination and control for these base stations. The network controller 130 may communicate with the base stations via a backhaul. The base stations also may communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.

The

wireless devices

120a, 120b, 120c may be dispersed throughout communications system 100, and each wireless device may be stationary or mobile. A wireless device also may be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, user equipment (UE) , etc.

A macro base station 110a may communicate with the communication network 140 over a wired or wireless communication link 126. The

wireless device

120a, 120b, 120c may communicate with a base station 110a-110d over a wireless communication link 122.

The

wireless communication links

122, 124 may include a plurality of carrier signals, frequencies, or frequency bands, each of which may include a plurality of logical channels. The

wireless communication links

122 and 124 may utilize one or more Radio access technologies (RATs) . Examples of RATs that may be used in a wireless communication link include 3GPP LTE, 3G, 4G, 5G (e.g., NR) , GSM, CDMA, WCDMA, Worldwide Interoperability for Microwave Access (WiMAX) , Time Division Multiple Access (TDMA) , and other mobile telephony communication technologies cellular RATs. Further examples of RATs that may be used in one or more of the various

wireless communication links

122, 124 within the communication system 100 include medium range protocols such as Wi-Fi, LTE-U, LTE-Direct, LAA, MuLTEfire, and relatively short range RATs such as ZigBee, Bluetooth, and Bluetooth Low Energy (LE) .

Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum Resource allocation (called a “resource block” ) may be 12 subcarriers (or 180 kHz) . Consequently, the nominal Fast File Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz) , respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 Resource blocks) , and there may be 1, 2, 4, 8 or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While descriptions of some embodiments may use terminology and examples associated with LTE technologies, various embodiments may be applicable to other wireless communications systems, such as a new Radio (NR) or 5G network. NR may utilize OFDM with a cyclic prefix (CP) on the uplink (UL) and downlink (DL) and include support for half-duplex operation using time division duplex (TDD) . A single component carrier bandwidth of 100 MHz may be supported. NR Resource blocks may span 12 sub-carriers with a sub-carrier bandwidth of 75 kHz over a 0.1 millisecond (ms) duration. Each Radio frame may consist of 50 subframes with a length of 10 ms. Consequently, each subframe may have a length of 0.2 ms. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. Beamforming may be supported and beam direction may be dynamically configured. Multiple Input Multiple Output (MIMO) transmissions with precoding may also be supported. MIMO configurations in the DL may support up to eight transmit antennas with multi-layer DL transmissions up to eight streams and up to two streams per wireless device. Multi-layer transmissions with up to 2 streams per wireless device may be supported. Aggregation of multiple cells may be supported with up to eight serving cells. Alternatively, NR may support a different air interface, other than an OFDM-based air interface.

Some mobile devices may be considered machine-type communication (MTC) or Evolved or enhanced machine-type communication (eMTC) mobile devices. MTC and eMTC mobile devices include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (for example, remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some mobile devices may be considered Internet-of-Things (IoT) devices or may be implemented as NB-IoT (narrowband internet of things) devices. A wireless device 120a-e may be included inside a housing that houses components of the wireless device, such as processor components, memory components, similar components, or a combination thereof.

In general, any number of communication systems and any number of wireless networks may be deployed in a given geographic area. Each communications system and wireless network may support a particular Radio access technology (RAT) and may operate on one or more frequencies. A RAT also may be referred to as a Radio technology, an air interface, etc. A frequency also may be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between communications systems of different RATs. In some cases, 4G/LTE and/or 5G/NR RAT networks may be deployed. For example, a 5G NSA network may utilize both 4G/LTE RAT in the 4G/LTE RAN side of the 5G NSA network and 5G/NR RAT in the 5G/NR RAN side of the 5G NSA network. The 4G/LTE RAN and the 5G/NR RAN may both connect to one another and a 4G/LTE core network (e.g., an EPC network) in a 5G NSA network.

In some embodiments, two or more wireless devices 120a-e (for example, illustrated as the wireless device 120a and the wireless device 120e) may communicate directly using one or more sidelink channels 124 (for example, without using a base station 110a-110d as an intermediary to communicate with one another) . For example, wireless device 120a-e may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or similar protocol) , a mesh network, or similar networks, or combinations thereof. In this case, the wireless device 120a-e may perform scheduling operations, resource selection operations, as well as other operations described elsewhere herein as being performed by the base station 110a

FIG. 2 is a component block diagram illustrating an example computing and wireless modem system 200 suitable for implementing any of the various embodiments. Various embodiments may be implemented on a number of single processor and multiprocessor computer systems, including a system-on-chip (SOC) or system in a package (SIP) .

With reference to FIGS. 1 and 2, the illustrated example wireless device 200 (which may be a SIP in some embodiments) includes a two

SOCs

202, 204 coupled to a clock 206, a voltage regulator 208, at least one SIM 268 and/or a SIM interface and a wireless transceiver 266 configured to send and receive wireless communications via an antenna (not shown) to/from network wireless devices, such as a base station 110a. In some embodiments, the first SOC 202 operate as central processing unit (CPU) of the wireless device that carries out the instructions of software application programs by performing the arithmetic, logical, control and input/output (I/O) operations specified by the instructions. In some embodiments, the second SOC 204 may operate as a specialized processing unit. For example, the second SOC 204 may operate as a specialized 5G processing unit responsible for managing high volume, high speed (e.g., 5 Gbps, etc. ) , and/or very high frequency short wave length (e.g., 28 GHz mmWave spectrum, etc. ) communications.

The first SOC 202 may include a digital signal processor (DSP) 210, a modem processor 212, a graphics processor 214, an application processor (AP) 216, one or more coprocessors 218 (e.g., vector co-processor) connected to one or more of the processors, memory 220, custom circuity 222, system components and resources 224, an interconnection/bus module 226, one or more temperature sensors 230, a thermal management unit 232, and a thermal power envelope (TPE) component 234. The second SOC 204 may include a 5G modem processor 252, a power management unit 254, an interconnection/bus module 264, the plurality of mmWave transceivers 256, memory 258, and various additional processors 260, such as an applications processor, packet processor, etc.

Each

processor

210, 212, 214, 216, 218, 252, 260 may include one or more cores, and each processor/core may perform operations independent of the other processors/cores. For example, the first SOC 202 may include a processor that executes a first type of operating system (e.g., FreeBSD, LINUX, OS X, etc. ) and a processor that executes a second type of operating system (e.g., MICROSOFT WINDOWS 10) . In addition, any or all of the

processors

210, 212, 214, 216, 218, 252, 260 may be included as part of a processor cluster architecture (e.g., a synchronous processor cluster architecture, an asynchronous or heterogeneous processor cluster architecture, etc. ) .

The first and

second SOC

202, 204 may include various system components, resources and custom circuitry for managing sensor data, analog-to-digital conversions, wireless data transmissions, and for performing other specialized operations, such as decoding data packets and processing encoded audio and video signals for rendering in a web browser. For example, the system components and resources 224 of the first SOC 202 may include power amplifiers, voltage regulators, oscillators, phase-locked loops, peripheral bridges, data controllers, memory controllers, system controllers, access ports, timers, and other similar components used to support the processors and software clients running on a wireless device. The system components and resources 224 and/or custom circuitry 222 may also include circuitry to interface with peripheral devices, such as cameras, electronic displays, wireless communication devices, external memory chips, etc.

The first and

second SOC

202, 204 may communicate via interconnection/bus module 250. The

various processors

210, 212, 214, 216, 218, may be interconnected to one or more memory elements 220, system components and resources 224, and custom circuitry 222, and a thermal management unit 232 via an interconnection/bus module 226. Similarly, the processor 252 may be interconnected to the power management unit 254, the mmWave transceivers 256, memory 258, and various additional processors 260 via the interconnection/bus module 264. The interconnection/

bus module

226, 250, 264 may include an array of reconfigurable logic gates and/or implement a bus architecture (e.g., CoreConnect, AMBA, etc. ) . Communications may be provided by advanced interconnects, such as high-performance networks-on chip (NoCs) .

The first and/or

second SOCs

202, 204 may further include an input/output module (not illustrated) for communicating with resources external to the SOC, such as a clock 206, a voltage regulator 208, one or more wireless transceivers 266, and at least one SIM 268 and/or SIM interface (i.e., an interface for receiving one or more SIM cards) . Resources external to the SOC (e.g., clock 206, voltage regulator 208) may be shared by two or more of the internal SOC processors/cores. The at least one SIM 268 (or one or more SIM cards coupled to one or more SIM interfaces) may store information supporting multiple subscriptions, including a first 5GNR subscription and a second 5GNR subscription in which the first 5GNR subscription and the second 5GNR subscription support service on a 5G non-standalone (NSA) network.

In addition to the example SIP 200 discussed above, various embodiments may be implemented in a wide variety of computing systems, which may include a single processor, multiple processors, multicore processors, or any combination thereof.

FIG. 3 is a component block diagram illustrating a software architecture 300 including a radio protocol stack for the user and control planes in wireless communications suitable for implementing any of the various embodiments. With reference to FIGS. 1–3, the wireless device 320 may implement the software architecture 300 to facilitate communication between a wireless device 320 (e.g., the wireless device 120a-120e, 200) and the base station 350 (e.g., the base station 110a) of a communication system (e.g., 100) . In various embodiments, layers in software architecture 300 may form logical connections with corresponding layers in software of the base station 350. The software architecture 300 may be distributed among one or more processors (e.g., the

processors

212, 214, 216, 218, 252, 260) . While illustrated with respect to one radio protocol stack, in a multi-SIM (subscriber identity module) wireless device, the software architecture 300 may include multiple protocol stacks, each of which may be associated with a different SIM (e.g., two protocol stacks associated with two SIMs, respectively, in a dual-SIM wireless communication device) . While described below with reference to LTE communication layers, the software architecture 300 may support any of variety of standards and protocols for wireless communications, and/or may include additional protocol stacks that support any of variety of standards and protocols wireless communications.

The software architecture 300 may include a Non-Access Stratum (NAS) 302 and an Access Stratum (AS) 304. The NAS 302 may include functions and protocols to support Packet filtering, security management, mobility control, session management, and traffic and signaling between a SIM (s) of the wireless device and its core network 140. The AS 304 may include functions and protocols that support communication between a SIM (s) and entities of supported access networks (e.g., a base station) . In particular, the AS 304 may include at least three layers (Layer 1, Layer 2, and Layer 3) , each of which may contain various sub-layers.

In the user and control planes, Layer 1 (L1) of the AS 304 may be a physical layer (PHY) 306, which may oversee functions that enable transmission and/or reception over the air interface. Examples of such physical layer 306 functions may include cyclic redundancy check (CRC) attachment, coding blocks, scrambling and descrambling, modulation and demodulation, signal measurements, MIMO, etc. The physical layer may include various logical channels, including the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) .

In the user and control planes, Layer 2 (L2) of the AS 304 may be responsible for the link between the wireless device 320 and the base station 350 over the physical layer 306. In the various embodiments, Layer 2 may include a Media Access Control (MAC) sublayer 308, a Radio link Control (RLC) sublayer 310, and a Packet data convergence protocol (PDCP) 312 sublayer, each of which form logical connections terminating at the base station 350.

In the control plane, Layer 3 (L3) of the AS 304 may include a Radio Resource Control (RRC) sublayer 3. While not shown, the software architecture 300 may include additional Layer 3 sublayers, as well as various upper layers above Layer 3. In various embodiments, the RRC sublayer 313 may provide functions including broadcasting system information, paging, and establishing and releasing an RRC signaling connection between the wireless device 320 and the base station 350.

In various embodiments, the PDCP sublayer 312 may provide uplink functions including multiplexing between different Radio bearers and logical channels, sequence number addition, handover data handling, integrity protection, ciphering, and header compression. In the downlink, the PDCP sublayer 312 may provide functions that include in-sequence delivery of data packets, duplicate data Packet detection, integrity validation, deciphering, and header decompression.

In the uplink, the RLC sublayer 310 may provide segmentation and concatenation of upper layer data packets, retransmission of lost data packets, and Automatic Repeat Request (ARQ) . In the downlink, while the RLC sublayer 310 functions may include reordering of data packets to compensate for out-of-order reception, reassembly of upper layer data packets, and ARQ.

In the uplink, MAC sublayer 308 may provide functions including multiplexing between logical and transport channels, random access procedure, logical channel priority, and hybrid-ARQ (HARQ) operations. In the downlink, the MAC layer functions may include channel mapping within a cell, de-multiplexing, discontinuous reception (DRX) , and HARQ operations.

While the software architecture 300 may provide functions to transmit data through physical media, the software architecture 300 may further include at least one host layer 314 to provide data transfer services to various applications in the wireless device 320. In some embodiments, application-specific functions provided by the at least one host layer 314 may provide an interface between the software architecture and the general purpose processor.

In other embodiments, the software architecture 300 may include one or more higher logical layer (e.g., transport, session, presentation, application, etc. ) that provide host layer functions. For example, in some embodiments, the software architecture 300 may include a network layer (e.g., IP layer) in which a logical connection terminates at a PDN gateway (PGW) . In some embodiments, the software architecture 300 may include an application layer in which a logical connection terminates at another device (e.g., end user device, server, etc. ) . In some embodiments, the software architecture 300 may further include in the AS 304 a hardware interface 316 between the physical layer 306 and the communication hardware (e.g., one or more radio frequency (RF) transceivers) .

FIG. 4 is a component block diagram illustrating a communication system 400 configured for wireless communication in accordance with various embodiments. With reference to FIGS. 1–4, the communication system 400 may include a wireless device 120, such as a multi-SIM wireless device, and one or more base stations 110 forming a wireless communication network 424, which may provide connections to external resources 422. External resources 422 may include sources of information outside of system 400, external entities participating with the system 400, and/or other resources.

A wireless device 120 may be configured by machine-readable instructions 406. Machine-readable instructions 406 may include one or more instruction modules. The instruction modules may include computer program modules. The instruction modules may include one or more of RRC connection monitoring module 408,

attachment module

410, 4G fallback synchronization module 412, subscription management module 414, and/or other instruction modules.

The RRC connection monitoring module 408 may be configured to maintain a counter to record the number of RRC connection releases (RRC_CONNECTION_RELs) received from a 5G NSA network for one or more subscriptions. The RRC connection monitoring module 408 may be configured to determine whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value. As one example, the time period may be one hour and the trigger value may be five. As another example, the time period may be one hour and the trigger value may be four. The RRC connection monitoring module 408 may be configured to determine whether a RRC connection release (RRC_CONNECTION_REL) is received from a base station of a 5G NSA network, such as an LTE cell (e.g., an eNB) for a first 5GNR subscription and/or a second 5GNR subscription. The RRC connection monitoring module 408 may be configured to store indications of RRC connection releases (RRC_CONNECTION_RELs) in a memory (e.g., electronic storage 424) . The RRC connection monitoring module 408 may be configured to include timestamps with the indications of the RRC connection releases (RRC_CONNECTION_RELs) , such as timestamps of when the RRC connection releases (RRC_CONNECTION_RELs) were received by the wireless device 120. The RRC connection monitoring module 408 may be configured to track the number of RRC connection release (RRC_CONNECTION_REL) indications having timestamps falling in the time window corresponding to the time period, such as the total number of RRC connection releases (RRC_CONNECTION_RELs) received in the one hour period prior to the most recent RRC connection release (RRC_CONNECTION_REL) . The RRC connection monitoring module 408 may be configured to operate as a counter and timer combination to track the total number of RRC connection releases (RRC_CONNECTION_RELs) received in a time period. For example, the RRC connection monitoring module 408 may track a total number of RRC connection releases (RRC_CONNECTION_RELs) received from a base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , during a time period tracked by the timer, and the counter may be reset at each expiration of the timer. The RRC connection monitoring module 408 may be configured to indicate to the attachment module 410, the 4G fallback synchronization module 412, and/or the subscription management module 414 that the total number of RRC connection releases (RRC_CONNECTION_RELs) received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) for a first 5GNR subscription, during the time period exceeds the trigger value and/or that a RRC connection release (RRC_CONNECTION_REL) for a first subscription and/or a second subscription was received from the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) .

The attachment module 410 may be configured to determine whether both a first 5GNR subscription and a second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network, such as a same LTE cell (e.g., an eNB) . The attachment module 410 may monitor and/or send detach requests (DETACH_REQs) sent by one or more 5GNR subscriptions of the wireless device 120. The attachment module 410 may monitor and/or send detach acceptances (DETACH_ACCEPTs) received by one or more 5GNR subscriptions of the wireless device 120. The attachment module 410 may monitor and/or send attach requests (ATTACH_REQs) sent by one or more 5GNR subscriptions of the wireless device 120. For example, the attachment monitoring module 410 may send attach requests (ATTACH_REQs) indicate DCNR is not supported, such as by a DCNR support flag bit being unset (e.g., DCNR = 0) , or attach requests (ATTACH_REQs) indicate DCNR is supported, such as by a DCNR support flag bit being set (e.g., DCNR = 1) . The attachment module 410 may monitor and/or send attach acceptances (ATTACH_ACCEPTs) received by one or more 5GNR subscriptions of the wireless device 120. The attachment module 410 may be configured to send a detach request in response to sending and/or receiving a 4G fallback synchronization request from the first 5GNR subscription to the second 5GNR subscription. The attachment module 410 may interface with the 4G fallback synchronization module 412 to determine whether a state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled. The attachment module 410 may be configured to sending a detach request in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled. The attachment module 410 may be configured to sending a detach request in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription.

The 4G fallback synchronization module 412 may be configured to monitor the RRC connection status indications from the RRC connection monitoring module 408 to determine whether a total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value. The 4G fallback synchronization module 412 may be configured to send a fourth generation (4G) fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value. The 4G fallback synchronization module 412 may be configured to set a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription.

The subscription management module 414 may be configured to disable monitor the states of the first 5GNR subscription and/or the second 5GNR subscription of the wireless device 120 and indicate the states of the first 5GNR subscription and/or the second 5GNR subscription of the wireless device 120 to one or more of the RRC connection monitoring module 408, the attachment module 410, and/or the 4G fallback synchronization module 412. The subscription management module 414 may be configured to determine whether both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network. The subscription management module 414 may be configured to determine whether the first 5GNR subscription and the second 5GNR subscription are associated with a same network operator. The subscription management module 414 may be configured to trigger 4G fallback for the first 5GNR subscription and/or the second 5GNR subscription of the wireless device 120. The subscription management module 414 may be configured to send indications of triggering 4G fallback for the first 5GNR subscription and/or the second 5GNR subscription to the attachment module 410 and/or 4G fallback synchronization module 412. The subscription management module may be configured to access and receive information from at least one SIM 268 on which are stored information supporting a first 5GNR subscription and a second 5GNR subscription.

The wireless device 120, remote platform (s) 110, and/or external resources 422 may be operatively linked via one or more electronic communication links of the wireless communication network. For example, the wireless communication network may establish links via a network such as the Internet and/or other networks.

The wireless device 120 may include electronic storage 424, one or more processors 426 (e.g., an AP processor 216,

modem processor

212, 252, etc. ) , one or more wireless transceivers 266, at least one SIM 268 (or SIM interfaces configured to connect to one or more SIM cards) , and/or other components. The wireless device 120 may include communication lines, or ports to enable the exchange of information with a network and/or other wireless device. The illustration of the wireless device 120 is not intended to be limiting. The wireless device 120 may include a plurality of hardware, software, and/or firmware components operating together to provide the functionality attributed herein to wireless device 120.

Electronic storage 424 may include non-transitory storage media that electronically stores information. The electronic storage media of electronic storage 424 may include one or both of system storage that is provided integrally (i.e., substantially non-removable) with the wireless device 120 and/or removable storage that is removably connectable to the wireless device 120 via, for example, a port (e.g., a universal serial bus (USB) port, a firewire port, etc. ) or a drive (e.g., a disk drive, etc. ) . Electronic storage 424 may include one or more of optically readable storage media (e.g., optical disks, etc. ) , magnetically readable storage media (e.g., magnetic tape, magnetic hard drive, floppy drive, etc. ) , electrical charge-based storage media (e.g., EEPROM, RAM, etc. ) , solid-state storage media (e.g., flash drive, etc. ) , and/or other electronically readable storage media. Electronic storage 424 may store software algorithms, information determined by processor (s) 426, information received from the wireless device 120, information received from remote platform (s) 110, and/or other information that enables the wireless device 120 to function as described herein.

The processor (s) 426 may be configured to provide information processing capabilities in the wireless device 120. As such, the processor (s) 426 may include one or more of a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and/or other mechanisms for electronically processing information. Although the processor (s) 426 is illustrated as a single entity, this is for illustrative purposes only. In some embodiments, the processor (s) 426 may include a plurality of processing units and/or processor cores. The processing units may be physically located within the same device, or processor (s) 426 may represent processing functionality of a plurality of devices operating in coordination. The processor (s) 426 may be configured to execute

modules

408, 410, 412, and/or 414 and/or other modules by software; hardware; firmware; some combination of software, hardware, and/or firmware; and/or other mechanisms for configuring processing capabilities on processor (s) 426. As used herein, the term “module” may refer to any component or set of components that perform the functionality attributed to the module. This may include one or more physical processors during execution of processor readable instructions, the processor readable instructions, circuitry, hardware, storage media, or any other components.

It should be appreciated that although

modules

408, 410, 412, and/or 414 are illustrated as being implemented within a single processing unit, in embodiments in which the processor (s) 426 includes multiple processing units and/or processor cores. The description of the functionality provided by the

different modules

408, 410, 412, and/or 414 described below is for illustrative purposes, and is not intended to be limiting, as any of

modules

408, 410, 412, and/or 414 may provide more or less functionality than is described. For example, one or more of the

modules

408, 410, 412, and/or 414 may be eliminated, and some or all of its functionality may be provided by

other modules

408, 410, 412, and/or 414. As another example, the processor (s) 426 may be configured to execute one or more additional modules that may perform some or all of the functionality attributed below to one of the

modules

408, 410, 412, and/or 414.

FIG. 5A is a process flow diagram illustrating a method 500 that may be performed by a processor of a multi-SIM wireless device configured with a first 5GNR subscription and a second 5GNR subscription for recovering from PS call failure in a 5G NSA network in accordance with various embodiments. With reference to FIGS. 1-5A, the method 500 may be implemented by one or more processors (e.g., 210, 212, 214, 216, 218, 252, 260, 426) of a wireless device (e.g., 120, 120a-120e, 200, 320) . In some embodiments, the operations of method 500 may be performed by a processor of a wireless device that is a multi-SIM wireless device in which a first 5GNR subscription and a second 5GNR subscription are associated with a same network operator.

In determination block 502, the processor may perform operations including determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network. For example, the processor may monitor the attach requests sent by the first 5GNR subscription and the second 5GNR subscription and the cell ID of the base station on which both subscriptions are camped to determine whether both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network. Both the 5GNR subscriptions sending attach requests indicating DCNR is supported and being camped on the same cell may indicate the both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network.

In response to determining that both the first 5GNR subscription and the second 5GNR subscription are not indicating DCNR is supported and/or both not attached to a same base station of a 5G NSA network (i.e., determination block 502 = “No” ) , the processor may continue to monitor the state of the subscriptions and perform operations including determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network in determination block 502.

In response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to a same base station of a 5G NSA network (i.e., determination block 502 = “Yes” ) , the processor may determine whether a RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in determination block 504. The base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , may send a RRC connection release for the first 5GNR subscription, thereby causing the data call (i.e., the PS call) to terminate.

In response to determining that RRC connection release is not received from the same base station of the 5G NSA network for the first 5GNR subscription (i.e., determination block 504 = “No” ) , the processor may await a RRC connection release and continue to determine whether a RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in determination block 504.

In response to determining that RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription (i.e., determination block 504 = “Yes” ) , the processor may store an indication of the RRC connection release in block 506. In some embodiments, as RRC connection releases for the first 5GNR subscription are received, indications of the RRC connection releases for the first 5GNR subscription may be stored. The indications of the RRC connection releases for the first 5GNR subscription may include timestamps of when the RRC connection releases for the first 5GNR subscription were received.

In determination block 508, the processor may determine whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value. As an example, the time period may be one hour and the trigger value may be five RRC connection releases. As another example, the time period may be one hour and the trigger value may be four RRC connection releases. The time period, such as one hour, may extend backward from the most recent received RRC connection release for the first 5GNR subscription. The processor may implement a counter to track the number of RRC connection release indications having timestamps falling in the time window corresponding to the time period, such as the total number of RRC connection releases received in the hour prior to the most recent RRC connection release. A number of RRC connection release indications having timestamps in the time window (i.e., during the time period tracked by the timer) may be compared to the trigger value to determine whether a total number of RRC connection releases received from a base station of a 5G NSA network during a time period exceeds a trigger value.

In some embodiments, a counter and timer combination may be used to track the total number of RRC connection releases received in a time period and the operations of block 506 may be optional. For example, the counter may track a total number of RRC connection releases received from a base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) , for a first 5GNR subscription during a time period tracked by the timer, and the counter may be reset at each expiration of the timer. In such embodiments, the processor may compare the counter value to the maximum counter value to determine whether a total number of RRC connection releases received from a base station of a 5G NSA network for the first 5GNR subscription during a time period exceeds a trigger value.

In response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network during the time period does not exceed the trigger value (i.e., determination block 508 = “No” ) , the processor may await a RRC connection release and continue to determine whether a RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in determination block 504.

In response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network for the first 5GNR subscription during the time period exceeds the trigger value (i.e., determination block 508 = “Yes” ) , the processor may perform operations including triggering fourth generation (4G) fallback for the first 5GNR subscription in block 509 and/or sending a fourth generation (4G) fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription in block 510. The 4G fallback synchronization indication may be a message, interrupt, flag bit setting, or other type indication provided to the second 5GNR subscription. In some embodiments, triggering 4G fallback for the first 5GNR subscription may include performing operations to fallback to a 4G mode for the first 5GNR subscription. 4G fallback may include detaching the first 5GNR subscription from the base station of a 5G NSA network, such as an LTE cell (e.g., an eNB) , and reattaching the first 5GNR subscription to that same base station of the 5G NSA network, such as the same LTE cell (e.g., an eNB) , with an attach request (ATTACH_REQ) indicating DCNR is not supported. In some embodiments, triggering of 4G fallback for the first 5GNR subscription in block 509 may occur prior to sending a 4G fallback synchronization indication to the second 5GNR subscription in block 510. In some embodiments, triggering of 4G fallback for the first 5GNR subscription in block 509 may occur concurrently with sending a 4G fallback synchronization indication to the second 5GNR subscription in block 510. In some embodiments, triggering of 4G fallback for the first 5GNR subscription in block 509 may occur after sending a 4G fallback synchronization indication to the second 5GNR subscription in block 510.

FIG. 5B is a process flow diagram illustrating a method 520 that may be performed by a processor of a multi-SIM wireless device configured with a first 5GNR subscription and a second 5GNR subscription for recovering from PS call failure in a 5G NSA network. With reference to FIGS. 1-5B, the method 520 may be implemented by one or more processors (e.g., 210, 212, 214, 216, 218, 252, 260, 426) of a wireless device (e.g., 120, 120a-120e, 200, 320) . In various embodiments, the operations of method 520 may be performed in conjunction with the operations of method 500 (FIG. 5A) . For example, the operations of method 520 may be performed in response to sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription in block 510 (FIG. 5A) . In some embodiments, the operations of method 520 may be performed by a processor of a wireless device that is a multi-SIM wireless device in which a first 5GNR subscription and a second 5GNR subscription are associated with a same network operator.

In block 522, the processor may perform operations including sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription. In various embodiments, the processor may send a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription. For example, the processor may send a detach request (DETACH_REQ) in response to receiving the 4G fallback synchronization request from the first 5GNR subscription.

In block 524, the processor may perform operations including receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network. For example, the processor may receive a detach acceptance (DETACH_ACCEPT) from the same base station of the 5G NSA network for the second 5GNR subscription.

In block 526, the processor may perform operations including sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the same base station of the 5G NSA network, such as a same LTE cell (e.g., an eNB) , for the second 5GNR subscription.

In block 528, the processor may perform operations including receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network. For example, the processor may receive an attach acceptance (ATTACH_ACCEPT) from the same base station of the 5G NSA network, such as a same LTE cell (e.g., an eNB) , for the second 5GNR subscription. In this manner, the processor may have successfully detached and reattached to the same base station of the 5G NSA network having fallen back to a 4G mode for the second 5GNR subscription (e.g., attached with DCNR not supported) . The reattachment in a 4G mode (e.g., with DCNR indicated as not supported) may support the PS call between the second 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) and the sending/receiving of data traffic. As a PS call between the second 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may be successfully established in 4G mode, the wireless device may be considered to have recovered from PS call failure. The user may be able to access the Internet in 4G mode, improving the user experience in comparison to repeated failing RRC connection establishment attempts when attached to the same base station of the 5G NSA network with DCNR indicated as supported.

FIG. 5C is a process flow diagram illustrating a method 530 that may be performed by a processor of a multi-SIM wireless device configured with a first 5GNR subscription and a second 5GNR subscription for recovering from PS call failure in a 5G NSA network. With reference to FIGS. 1-5C, the method 530 may be implemented by one or more processors (e.g., 210, 212, 214, 216, 218, 252, 260, 426) of a wireless device (e.g., 120, 120a-120e, 200, 320) . In various embodiments, the operations of method 530 may be performed in conjunction with the operations of method 500 (FIG. 5A) . For example, the operations of method 530 may be performed in response to sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription in block 510 (FIG. 5A) . In some embodiments, the operations of method 530 may be performed by a processor of a wireless device that is a multi-SIM wireless device in which a first 5GNR subscription and a second 5GNR subscription are associated with a same network operator.

In block 532, the processor may perform operations including setting a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled. In some embodiments, the processor may set a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription.

In determination block 534, the processor may determine whether a RRC connection release is received from the same base station of the 5G NSA network for the second 5GNR subscription.

In response to determining a RRC connection release is not received (i.e., determination block 534 = “No” ) , the processor may continue to monitor for RRC connection releases and determine whether a RRC connection release is received from the same base station of the 5G NSA network for the second 5GNR subscription in determination block 534.

In response to determining that a RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription is received (i.e., determination block 536 = “Yes” ) , the processor may determine whether the state of the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in determination block 536.

In response to determining that the state of the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is not enabled (i.e., determination block 536 = “No” ) , the processor may continue to monitor for RRC connection releases and determine whether a RRC connection release is received from the same base station of the 5G NSA network for the second 5GNR subscription in determination block 534.

In response to determining that the state of the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled (i.e., determination block 536 = “Yes” ) , the processor may perform operations of

block

522, 524, 526, and 528 as discussed above with reference to method 520 (FIG. 5B) to detach and reattach to the same base station of the 5G NSA network having fallen back to a 4G mode for the second 5GNR subscription (e.g., attached with DCNR not supported) . The reattachment in a 4G mode (e.g., with DCNR indicated as not supported) may support the PS call between the second 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) and the sending/receiving of data traffic. As a PS call between the second 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may be successfully established in 4G mode, the wireless device may be considered to have recovered from PS call failure. The user may be able to access the Internet in 4G mode, improving the user experience in comparison to repeated failing RRC connection establishment attempts when attached to the same base station of the 5G NSA network with DCNR indicated as supported.

FIG. 5D is a process flow diagram illustrating a method 540 that may be performed by a processor of a multi-SIM wireless device configured with a first 5GNR subscription and a second 5GNR subscription for triggering 4G fallback for the first 5GNR subscription. With reference to FIGS. 1-5D, the method 540 may be implemented by one or more processors (e.g., 210, 212, 214, 216, 218, 252, 260, 426) of a wireless device (e.g., 120, 120a-120e, 200, 320) . In various embodiments, the operations of method 540 may be performed in conjunction with the operations of method 500 (FIG. 5A) , 520 (FIG. 5B) , and/or 530 (FIG. 5C) . For example, the operations of method 540 may be performed as part of the operations of block 509 (FIG. 5A) to trigger 4G fallback for the first 5GNR subscription. As a specific example, the operations of the method 540 may be performed in response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network for the first 5GNR subscription during the time period exceeds the trigger value (i.e., determination block 508 (FIG. 5A) = “Yes” ) . In some embodiments, the operations of method 540 may be performed by a processor of a wireless device that is a multi-SIM wireless device in which a first 5GNR subscription and a second 5GNR subscription are associated with a same network operator.

In block 542, the processor may perform operations including sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription. In various embodiments, the processor may send a detach request (DETACH_REQ) to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network for the first 5GNR subscription during the time period exceeds the trigger value. In various embodiments, the processor may send a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to sending the 4G fallback synchronization request from the first 5GNR subscription to the second 5GNR subscription. For example, the processor may send a detach request (DETACH_REQ) in response to sending the 4G fallback synchronization request from the first 5GNR subscription.

In block 544, the processor may perform operations including receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network. For example, the processor may receive a detach acceptance (DETACH_ACCEPT) from the same base station of the 5G NSA network for the first 5GNR subscription.

In block 546, the processor may perform operations including sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network. For example, a DCNR support flag bit may be unset (e.g., DCNR = 0) in an attach request (ATTACH_REQ) sent to the same base station of the 5G NSA network, such as a same LTE cell (e.g., an eNB) , for the first 5GNR subscription.

In block 548, the processor may perform operations including receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network. For example, the processor may receive an attach acceptance (ATTACH_ACCEPT) from the same base station of the 5G NSA network, such as a same LTE cell (e.g., an eNB) , for the first 5GNR subscription. In this manner, the processor may have successfully detached and reattached to the same base station of the 5G NSA network having fallen back to a 4G mode for the first 5GNR subscription (e.g., attached with DCNR not supported) . The reattachment in a 4G mode (e.g., with DCNR indicated as not supported) may support the PS call between the first 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) and the sending/receiving of data traffic. As a PS call between the first 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may be successfully established in 4G mode, the wireless device may be considered to have recovered from PS call failure. The user may be able to access the Internet in 4G mode, improving the user experience in comparison to repeated failing RRC connection establishment attempts when attached to the same base station of the 5G NSA network with DCNR indicated as supported.

FIG. 5E is a process flow diagram illustrating a method 550 that may be performed by a processor of a multi-SIM wireless device configured with a first 5GNR subscription and a second 5GNR subscription for triggering 4G fallback for the first 5GNR subscription. With reference to FIGS. 1-5E, the method 550 may be implemented by one or more processors (e.g., 210, 212, 214, 216, 218, 252, 260, 426) of a wireless device (e.g., 120, 120a-120e, 200, 320) . In various embodiments, the operations of method 550 may be performed in conjunction with the operations of method 500 (FIG. 5A) , 520 (FIG. 5B) , and/or 530 (FIG. 5C) . For example, the operations of method 550 may be performed as part of the operations of block 509 (FIG. 5A) to trigger 4G fallback for the first 5GNR subscription. As a specific example, the operations of method 550 may be performed in response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network for the first 5GNR subscription during the time period exceeds the trigger value (i.e., determination block 508 (FIG. 5A) = “Yes” ) . In some embodiments, the operations of method 550 may be performed by a processor of a wireless device that is a multi-SIM wireless device in which a first 5GNR subscription and a second 5GNR subscription are associated with a same network operator.

In determination block 552, the processor may determine whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription.

In some embodiments, the processor may determine whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that the total number of RRC connection releases received from the base station of the 5G NSA network for the first 5GNR subscription during the time period exceeds the trigger value. In some embodiments, the processor may determine whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in response to sending the 4G fallback synchronization request from the first 5GNR subscription to the second 5GNR subscription.

In response to determining a RRC connection release is not received (i.e., determination block 552 = “No” ) , the processor may continue to monitor for RRC connection releases and determine whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription in determination block 552.

In response to determining that at least one additional RRC connection release from the same base station of the 5G NSA network for the first 5GNR subscription is received (i.e., determination block 552 = “Yes” ) , the processor may perform operations of

block

542, 544, 546, and 548 as discussed above with reference to method 540 (FIG. 5D) to detach and reattach to the same base station of the 5G NSA network having fallen back to a 4G mode for the first 5GNR subscription (e.g., attached with DCNR not supported) . The fallback to 4G mode for data calls may result in service requests for data traffic (e.g., data traffic associated with an Internet browser, social media application, etc. ) to be issued as 4G mode service requests. The reattachment in a 4G mode (e.g., with DCNR indicated as not supported) may support the PS call between the first 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) and the sending/receiving of data traffic. As a PS call between the first 5GNR subscription of the multi-SIM wireless device and the base station of the 5G NSA network, such as an LTE cell (e.g., an eNB) may be successfully established in 4G mode, the wireless device may be considered to have recovered from PS call failure. The user may be able to access the Internet in 4G mode, improving the user experience in comparison to repeated failing RRC connection establishment attempts when attached to the same base station of the 5G NSA network with DCNR indicated as supported.

FIG. 6A is a call flow diagram illustrating example interactions between two 5G new radio (5GNR) subscriptions (e.g., a first 5GNR subscription labeled SUB1 (UE) in FIG. 6A and a second 5GNR subscription labeled SUB2 (UE) in FIG. 6A) of a wireless device (such as the

wireless device

120, 200, 320, 120a-120e) and a base station (e.g.,

base station

110a, 350, 110) of a 5G NSA network (e.g., network 100) accordance with various embodiments. With reference to FIGS. 1-6A, the interactions illustrated in FIG. 6A may reflect example implementations of the various embodiment methods for recovering from PS call failure in a 5G NSA network, such as one or more operations of

methods

500, 520, and 540. FIG. 6A illustrates an example implementation in which in response to a 4G fallback synchronization indication (labeled fallback_to_4G_sync_req in FIG. 6A) , both a first 5GNR subscription (labeled SUB1 (UE) in FIG. 6A) and a second 5GNR subscription (labeled SUB2 (UE) in FIG. 6A) detach and reattach to the same LTE cell of the 5G NSA network (labeled LTE Cell_1 in FIG. 6A) indicating DCNR is not supported.

FIG. 6B is a call flow diagram illustrating example interactions between two 5G new radio (5GNR) subscriptions (e.g., a first 5GNR subscription labeled SUB1 (UE) in FIG. 6B and a second 5GNR subscription labeled SUB2 (UE) in FIG. 6B) of a wireless device (such as the

wireless device

120, 200, 320, 120a-120e) and a base station (e.g.,

base station

110a, 350, 110) of a 5G NSA network (e.g., network 100) accordance with various embodiments. With reference to FIGS. 1-6B, the interactions illustrated in FIG. 6B may reflect example implementations of the various embodiment methods for recovering from PS call failure in a 5G NSA network, such as one or more operations of

methods

500, 530, and 540. FIG. 6B illustrates an example implementation in which in response to a 4G fallback synchronization indication (labeled fallback_to_4G_sync_req in FIG. 6B) , a state of a 4G synchronization flag is set to indicate 4G mode fallback is enabled. FIG. 6B illustrates that a second 5GNR subscription (labeled SUB2 (UE) in FIG. 6B) may attempt an additional RRC connection establishment. In response to receiving a RRC connection release from the same LTE cell of the 5G NSA network (labeled LTE Cell_1 in FIG. 6B) that was causing network issues (e.g., network triggered RRC connection releases) for the first 5GNR subscription (labeled SUB1 (UE) in FIG. 6B) , the second 5GNR subscription (labeled SUB2 (UE) in FIG. 6B) may detach and reattach to the same LTE cell of the 5G NSA network (labeled LTE Cell_1 in FIG. 6A) indicating DCNR is not supported.

FIG. 7 is a component block diagram of a network computing device 700 suitable for use with various embodiments. Such network computing devices may include at least the components illustrated in FIG. 7. With reference to FIGS. 1–7, the network computing device 700 may include a processor 701 coupled to volatile memory 702 and a large capacity nonvolatile memory, such as a disk drive 703. The network computing device 700 may also include a peripheral memory access device such as a floppy disc drive, compact disc (CD) or digital video disc (DVD) drive 706 coupled to the processor 701. The network computing device 700 may also include network access ports 704 (or interfaces) coupled to the processor 701 for establishing data connections with a network, such as the Internet and/or a local area network coupled to other system computers and servers. The network computing device 700 may include one or more antennas 707 for sending and receiving electromagnetic radiation that may be connected to a wireless communication link. The network computing device 700 may include additional access ports, such as USB, Firewire, Thunderbolt, and the like for coupling to peripherals, external memory, or other devices.

FIG. 8 is a component block diagram of a wireless device 800 suitable for use with various embodiments. With reference to FIGS. 1–8, various embodiments may be implemented on a variety of wireless devices 800 (e.g., the wireless device 120a-120e, 200, 320, 120a-120e) , an example of which is illustrated in FIG. 8 in the form of a smartphone. The wireless device 800 may include a first SOC 202 (e.g., a SOC-CPU) coupled to a second SOC 204 (e.g., a 5G capable SOC) . The first and

second SOCs

202, 204 may be coupled to

internal memory

424, 816, a display 812, and to a speaker 814. The first and

second SOCs

202, 204 may also be coupled to at least one SIM 268 and/or a SIM interface that may store information supporting a first 5GNR subscription and a second 5GNR subscription, which support service on a 5G non-standalone (NSA) network. Additionally, the wireless device 800 may include an antenna 804 for sending and receiving electromagnetic radiation that may be connected to a wireless transceiver 266 coupled to one or more processors in the first and/or

second SOCs

202, 204. The wireless device 800 may also include menu selection buttons or rocker switches 820 for receiving user inputs.

The wireless device 800 also includes a sound encoding/decoding (CODEC) circuit 810, which digitizes sound received from a microphone into data packets suitable for wireless transmission and decodes received sound data packets to generate analog signals that are provided to the speaker to generate sound. Also, one or more of the processors in the first and

second SOCs

202, 204, wireless transceiver 266 and CODEC 810 may include a digital signal processor (DSP) circuit (not shown separately) .

The processors of the wireless network computing device 700 and the wireless device 800 may be any programmable microprocessor, microcomputer or multiple processor chip or chips that can be configured by software instructions (applications) to perform a variety of functions, including the functions of the various embodiments described below. In some mobile devices, multiple processors may be provided, such as one processor within an SOC 204 dedicated to wireless communication functions and one processor within an SOC 202 dedicated to running other applications. Software applications may be stored in the

memory

424, 816 before they are accessed and loaded into the processor. The processors may include internal memory sufficient to store the application software instructions.

As used in this application, the terms “component, ” “module, ” “system, ” and the like are intended to include a computer-related entity, such as, but not limited to, hardware, firmware, a combination of hardware and software, software, or software in execution, which are configured to perform particular operations or functions. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a wireless device and the wireless device may be referred to as a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one processor or core and/or distributed between two or more processors or cores. In addition, these components may execute from various non-transitory computer readable media having various instructions and/or data structures stored thereon. Components may communicate by way of local and/or remote processes, function or procedure calls, electronic signals, data packets, memory read/writes, and other known network, computer, processor, and/or process related communication methodologies.

A number of different cellular and mobile communication services and standards are available or contemplated in the future, all of which may implement and benefit from the various embodiments. Such services and standards include, e.g., third generation partnership project (3GPP) , LTE systems, third generation wireless mobile communication technology (3G) , fourth generation wireless mobile communication technology (4G) , fifth generation wireless mobile communication technology (5G) , global system for mobile communications (GSM) , universal mobile telecommunications system (UMTS) , 3GSM, general Packet Radio service (GPRS) , code division multiple access (CDMA) systems (e.g., cdmaOne, CDMA1020TM) , enhanced data rates for GSM evolution (EDGE) , advanced mobile phone system (AMPS) , digital AMPS (IS-136/TDMA) , evolution-data optimized (EV-DO) , digital enhanced cordless telecommunications (DECT) , Worldwide Interoperability for Microwave Access (WiMAX) , wireless local area network (WLAN) , Wi-Fi Protected Access I &II (WPA, WPA2) , and integrated digital enhanced network (iDEN) . Each of these technologies involves, for example, the transmission and reception of voice, data, signaling, and/or content messages. It should be understood that any references to terminology and/or technical details related to an individual telecommunication standard or technology are for illustrative purposes only, and are not intended to limit the scope of the claims to a particular communication system or technology unless specifically recited in the claim language.

Various embodiments illustrated and described are provided merely as examples to illustrate various features of the claims. However, features shown and described with respect to any given embodiment are not necessarily limited to the associated embodiment and may be used or combined with other embodiments that are shown and described. Further, the claims are not intended to be limited by any one example embodiment.

The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the operations of various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of operations in the foregoing embodiments may be performed in any order. Words such as “thereafter, ” “then, ” “next, ” etc. are not intended to limit the order of the operations; these words are used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a, ” “an, ” or “the” is not to be construed as limiting the element to the singular.

Various illustrative logical blocks, modules, components, circuits, and algorithm operations described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and operations have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such embodiment decisions should not be interpreted as causing a departure from the scope of the claims.

The hardware used to implement various illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (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. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of receiver smart objects, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Alternatively, some operations or methods may be performed by circuitry that is specific to a given function.

In one or more embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable storage medium or non-transitory processor-readable storage medium. The operations of a method or algorithm disclosed herein may be embodied in a processor-executable software module or processor-executable instructions, which may reside on a non-transitory computer-readable or processor-readable storage medium. Non-transitory computer-readable or processor-readable storage media may be any storage media that may be accessed by a computer or a processor. By way of example but not limitation, such non-transitory computer-readable or processor-readable storage media may include RAM, ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage smart objects, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of non-transitory computer-readable and processor-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable storage medium and/or computer-readable storage medium, which may be incorporated into a computer program product.

The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the claims. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the claims. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

Claims

A method for recovering from packet switched (PS) call failure in a fifth generation (5G) non-standalone (NSA) network performed by a processor of a multi-subscriber identity module (SIM) wireless device configured with a first 5G new radio (5GNR) subscription and a second 5GNR subscription, comprising:

determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G NSA network;

determining whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value in response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to the same base station of the 5G NSA network; and

in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value:

triggering fourth generation (4G) fallback for the first 5GNR subscription; and

sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription.
The method of claim 1, further comprising:

sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The method of claim 2, further comprising:

setting a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

determining whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in response to receiving a RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription;

sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled;

receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The method of claim 1, wherein triggering 4G fallback for the first 5GNR subscription comprises:

determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The method of claim 4, wherein the time period is one hour and the trigger value is four.
The method of claim 1, wherein triggering 4G fallback for the first 5GNR subscription comprises:

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The method of claim 6, wherein the time period is one hour and the trigger value is five.
The method of claim 1, wherein the first 5GNR subscription and the second 5GNR subscription are associated with a same network operator.
A wireless device, comprising:

at least one subscriber identity module (SIM) having stored thereon information supporting a first fifth generation (5G) new radio (5GNR) subscription and a second 5GNR subscription, wherein the first 5GNR subscription and the second 5GNR subscription support service on a 5G non-standalone (NSA) network; and

a processor coupled to the at least one SIM and configured to:

determine whether both the first 5GNR subscription and the second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G NSA network;

determine whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value in response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to the same base station of the 5G NSA network; and

in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value:

trigger fourth generation (4G) fallback for the first 5GNR subscription; and

send a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription.
The wireless device of claim 9, wherein the processor is further configured to:

send a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

receive a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

send an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receive an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 10, wherein the processor is further configured to:

set a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

determine whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in response to receiving an RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription;

send a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled;

receive a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

send an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receive an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 9, wherein the processor is further configured to trigger fourth 4G fallback for the first 5GNR subscription by:

determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 12, wherein the time period is one hour and the trigger value is four.
The wireless device of claim 9, wherein the processor is further configured to trigger fourth 4G fallback for the first 5GNR subscription by:

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 14, wherein the time period is one hour and the trigger value is five.
The wireless device of claim 9, wherein the first 5GNR subscription and the second 5GNR subscription are associated with a same network operator.
A non-transitory processor-readable storage medium having stored thereon processor-executable instructions configured to cause a processor of a multi-subscriber identity module (SIM) wireless device configured with a first fifth generation (5G) new radio (5GNR) subscription and a second 5GNR subscription to perform operations comprising:

determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G non-standalone (NSA) network;

determining whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value in response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to the same base station of the 5G NSA network; and

in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value:

triggering fourth generation (4G) fallback for the first 5GNR subscription; and

sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription.
The non-transitory processor-readable storage medium of claim 16, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations further comprising:

sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The non-transitory processor-readable storage medium of claim 18, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations further comprising:

setting a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

determining whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in response to receiving an RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription;

sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled;

receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The non-transitory processor-readable storage medium of claim 16, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations such that triggering 4G fallback for the first 5GNR subscription comprises:

determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The non-transitory processor-readable storage medium of claim 20, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations such that the time period is one hour and the trigger value is four.
The non-transitory processor-readable storage medium of claim 16, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations such that triggering 4G fallback for the first 5GNR subscription comprises:

sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription;

receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The non-transitory processor-readable storage medium of claim 22, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations such that the time period is one hour and the trigger value is five.
The non-transitory processor-readable storage medium of claim 16, wherein the stored processor-executable instructions are configured to cause a processor of a multi-SIM wireless device to perform operations such that the first 5GNR subscription and the second 5GNR subscription are associated with a same network operator.
A wireless device, comprising:

at least one subscriber identity module (SIM) having stored thereon information supporting a first fifth generation (5G) new radio (5GNR) subscription and a second 5GNR subscription, wherein the first 5GNR subscription and the second 5GNR subscription support service on a 5G non-standalone (NSA) network;

means for determining whether both the first 5GNR subscription and the second 5GNR subscription are indicating dual connectivity with new radio (DCNR) is supported while attached to a same base station of a 5G non-standalone (NSA) network;

means for determining whether a total number of radio resource control (RRC) connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during a time period is equal to a trigger value in response to determining that both the first 5GNR subscription and the second 5GNR subscription are indicating DCNR is supported while attached to the same base station of the 5G NSA network; and

in response to determining that the total number of RRC connection releases received from the same base station of the 5G NSA network for the first 5GNR subscription during the time period is equal to the trigger value:

means for triggering fourth generation (4G) fallback for the first 5GNR subscription; and

means for sending a 4G fallback synchronization indication from the first 5GNR subscription to the second 5GNR subscription.
The wireless device of claim 25, further comprising:

means for sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

means for receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

means for sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

means for receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 26, further comprising:

means for setting a state of a 4G synchronization flag for the second 5GNR subscription to indicate 4G mode fallback is enabled in response to receiving the 4G fallback synchronization request from the first 5GNR subscription;

means for determining whether the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled in response to receiving an RRC connection release from the same base station of the 5G NSA network for the second 5GNR subscription;

means for sending a detach request to the same base station of the 5G NSA network for the second 5GNR subscription in response to determining that the state of the 4G synchronization flag for the second 5GNR subscription indicates 4G mode fallback is enabled;

means for receiving a detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network;

means for sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the second 5GNR subscription in response to receiving the detach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network; and

means for receiving an attach acceptance for the second 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 25, wherein means for triggering 4G fallback for the first 5GNR subscription comprises:

means for determining whether at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

means for sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription in response to determining that at least one additional RRC connection release is received from the same base station of the 5G NSA network for the first 5GNR subscription;

means for receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

means for sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

means for receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 28, wherein the time period is one hour and the trigger value is four.
The wireless device of claim 25, wherein means for triggering 4G fallback for the first 5GNR subscription comprises:

means for sending a detach request to the same base station of the 5G NSA network for the first 5GNR subscription;

means for receiving a detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network;

means for sending an attach request indicating DCNR is not supported to the same base station of the 5G NSA network for the first 5GNR subscription in response to receiving the detach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network; and

means for receiving an attach acceptance for the first 5GNR subscription from the same base station of the 5G NSA network.
The wireless device of claim 20, wherein the time period is one hour and the trigger value is five.
The wireless device of claim 25, wherein the first 5GNR subscription and the second 5GNR subscription are associated with a same network operator.