WO2021212400A1

WO2021212400A1 - Subscriber identity module (sim) registration in dual-sim device

Info

Publication number: WO2021212400A1
Application number: PCT/CN2020/086340
Authority: WO
Inventors: Yi Liu; Jinglin Zhang; Haojun WANG; Zhenqing CUI; Fojian ZHANG; Jian Li; Hong Wei
Original assignee: Qualcomm Incorporated
Priority date: 2020-04-23
Filing date: 2020-04-23
Publication date: 2021-10-28

Abstract

Methods, systems, and devices for wireless communications are described. For example, a method for wireless communications at a user equipment (UE), may include registering a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The UE may identify a trigger to register a second subscriber identity module of the UE. The UE may also search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. In some cases, the UE may determine that the first subscriber identity module and the second subscriber identity module are associated with a same operator, where searching for the synchronization signal of the carrier on the first synchronization signal frequency is based on the determination.

Description

SUBSCRIBER IDENTITY MODULE (SIM) REGISTRATION IN DUAL-SIM DEVICE

FIELD OF TECHNOLOGY

The following relates generally to wireless communications and more specifically to subscriber identity module (SIM) registration in dual-SIM devices.

BACKGROUND

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) . A wireless multiple-access communications system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE) .

In some wireless communications systems, a UE may search for a synchronization signal to synchronize and register to a network. In some cases, UE registration speed may be delayed if the UE has to search over a substantial number of frequencies to locate synchronization signals. For example, in some carriers asynchronization signal block may not be located at the center frequency the carrier and thus locating the synchronization signal block may require a raster scan within the carrier frequency range. Further delays may occur based on the more frequencies or carriers that a UE searches to register to a network. A UE may maintain a history of previously used frequencies, however, in some cases the historical list may be empty or out of date. As a result, improved techniques may be desired for ensuring efficient UE registration for improved quality of communications.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support subscriber identity module (SIM) registration in dual-SIM devices. Generally, the described techniques provide for efficient UE registration using frequency sharing between SIMs in a dual-SIM or multi-SIM device. A dual-SIM device may be a user equipment (UE) configured with two or more SIM cards, which may allow the UE to use either of the SIMs to communicate with a network. In some cases, a dual-SIM UE may be used such that one SIM is associated with a personal phone number and another SIM is associated with a business number. Each SIM may undergo a separate registration procedure with a network to access the network for future communications. For example, the registration procedure may begin with a random access procedure where the UE may search a number of frequencies for synchronization signals (e.g., a synchronization signal block (SSB) ) from the base station. After the frequency of the synchronization signals is found, the SIM may proceed through the registration procedure and connect to the network. The other SIM(s) in the device may also undergo a registration procedure concurrently or at a different time.

As described herein, the registered SIM may assist the unregistered SIM in the registration process to speed up the registration of the unregistered SIM. For instance, the registered SIM may share the frequency it is using or recently used to connect to the network with the unregistered SIM before the unregistered SIM begins searching frequencies for synchronization signals. Thus, a first SIM may share information with a second SIM to speed up the registration of the second SIM. In some examples, the first SIM may register to the network and share the frequency used for registration with the second SIM to optimize the registration of the second SIM. In some examples, when the second SIM initiates a registration process, an initial shared frequency search may be performed at the second SIM. In some examples, the shared frequency search includes one frequency to search, which is the frequency used and shared by the first SIM. The shared frequency may be searched before an acquisition (ACQ) database (DB) or full band scan is performed. With this shared frequency from the first SIM, there is a high probability that the second SIM may access network service as the first SIM already camped to the frequency successfully.

A method of wireless communications at a UE is described. The method may include registering a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identifying a trigger to register a second subscriber identity module of the UE, and searching for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identify a trigger to register a second subscriber identity module of the UE, and search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for registering a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identifying a trigger to register a second subscriber identity module of the UE, and searching for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identify a trigger to register a second subscriber identity module of the UE, and search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining that the first subscriber identity module and the second subscriber identity module may be associated with a same operator, where searching for the synchronization signal of the carrier on the first synchronization signal frequency may be based on the determining.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for acquiring the synchronization signal of the carrier based on the searching, and registering the second subscriber identity module to the network on the carrier based on acquiring the synchronization signal.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for storing, based on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the trigger to register the second subscriber identity module of the UE may include operations, features, means, or instructions for identifying an indicator to recover network service after being out of service.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the trigger to register the second subscriber identity module of the UE may include operations, features, means, or instructions for identifying an indicator of a presence of the second subscriber identity module.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the trigger to register the second subscriber identity module of the UE may include operations, features, means, or instructions for identifying a roaming mode for registering the second subscriber identity module of the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first synchronization signal frequency may be located at a frequency offset from a center frequency of the carrier.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for scanning an acquisition database for registering the second subscriber identity module of the UE to one or more networks based on an unsuccessful registration to the carrier.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for scanning one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first subscriber identity module may be associated with a first subscriber and the second subscriber identity module may be associated with a second subscriber.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first subscriber and the second subscriber may be configured to communicate on carriers of the network configured for standalone registration of the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports subscriber identity module (SIM) registration in dual-SIM device in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIG. 3 illustrates an example of a flowchart that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIG. 4 illustrates an example of a process flow that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIGs. 5 and 6 show block diagrams of devices that support SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIG. 7 shows a block diagram of a communications manager that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIG. 8 shows a diagram of a system including a device that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

FIGs. 9 through 14 show flowcharts illustrating methods that support SIM registration in dual-SIM device in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

A user equipment (UE) may be configured with more than one subscriber identity module (SIM) , which may be referred to as a multi-SIM device. As described herein, a dual-SIM device may be an example of a multi-SIM device. The techniques described herein may refer to a dual-SIM device, however the techniques are not limited to a dual-SIM device and may apply to any multi-SIM device. The SIMs discussed herein may be a physical SIM card or a virtual SIM card. A dual-SIM device may allow the UE to use either of the SIMs to communicate with a network. In some cases, a dual-SIM UE may be used to have one SIM associated with a personal phone number and another SIM associated with a business number. In another example, one SIM may be associated with a phone number for making calls and another SIM may be associated with a phone number for connecting to the internet. Each SIM in a dual-SIM device may be associated with a separate subscription to a network operator, and in some cases both SIMs may be associated with subscriptions to the same network operator.

Each SIM may undergo a separate registration procedure with a network to access the network for future communications. For example, the registration procedure may begin with a random access procedure where the UE may search a number of frequencies for synchronization signals (e.g., a synchronization signal block (SSB) ) from the base station. After the frequency of the synchronization signals is found, the SIM may proceed through the registration procedure and connect to the network. The other SIM (s) in the device may also undergo a registration procedure. In some cases, dual-SIM devices are limited in that there is no sharing of information between the SIMs. Thus, current SIM registration procedures may not allow for one SIM to share frequency information for efficient registration of another SIM in the same UE.

If both SIMs of a UE have a subscription to the same operator, then the SIMs may share frequency information for efficient registration with the other SIM. For instance, a first SIM may register to the network and share the frequency used for registration with a second SIM to optimize the registration speed of the second SIM. Specifically, a shared frequency search may be performed at the second SIM based on the frequency information from the first SIM. In some examples, the shared frequency search includes searching the one frequency used to connect to the network by the first SIM. The second SIM may search the shared frequency before an acquisition (ACQ) database (DB) or full band scan is performed and may proceed with the ACQ DB scan or full band scan if the search of the shared frequency is not successful. With the shared frequency from the first SIM, there is a high probability that the second SIM may access network service as the first SIM already camped to the frequency successfully.

If the second SIM is unable to connect to the network via the shared frequency, the UE may attempt an ACQ DB scan. An ACQ DB scan may include a limited list of frequencies (e.g., ten frequencies) that were previously used by the second SIM that successfully connected to the network. In some cases, the ACQ DB is empty or outdated. If the ACQ DB scan is also unsuccessful, then the UE may attempt a full band scan. A full band scan may include searching all frequencies (e.g., according to a frequency raster) in the frequency band.

Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, process flows, and flowcharts that relate to SIM registration in dual-SIM device.

FIG. 1 illustrates an example of a wireless communications system 100 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

The base stations 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may be devices in different forms or having different capabilities. The base stations 105 and the UEs 115 may wirelessly communicate via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base station 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a base station 105 and a UE 115 may support the communication of signals according to one or more radio access technologies.

The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, the base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment) , as shown in FIG. 1.

The base stations 105 may communicate with the core network 130, or with one another, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (e.g., via an S1, N2, N3, or other interface) . The base stations 105 may communicate with one another over the backhaul links 120 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) , or indirectly (e.g., via core network 130) , or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

One or more of the base stations 105 described herein may include or may be referred to by a person having ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or other suitable terminology.

A UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the base stations 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in FIG. 1.

The UEs 115 and the base stations 105 may wirelessly communicate with one another via one or more communication links 125 over one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP) ) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR) . Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information) , control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

In some examples (e.g., in a carrier aggregation configuration) , a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN) ) and may be positioned according to a channel raster for discovery by the UEs 115. A carrier may be operated in a standalone mode where initial acquisition and connection may be conducted by the UEs 115 via the carrier, or the carrier may be operated in a non-standalone mode where a connection is anchored using a different carrier (e.g., of the same or a different radio access technology) .

The communication links 125 shown in the wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of determined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz) ) . Devices of the wireless communications system 100 (e.g., the base stations 105, the UEs 115, or both) may have hardware configurations that support communications over a particular carrier bandwidth or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 or UEs 115 that support simultaneous communications via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured for operating over portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

Signal waveforms transmitted over a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) . In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. A wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers or beams) , and the use of multiple spatial layers may further increase the data rate or data integrity for communications with a UE 115.

One or more numerologies for a carrier may be supported, where a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time and communications for the UE 115 may be restricted to one or more active BWPs.

The time intervals for the base stations 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T _s=1/ (Δf _max·N _f) seconds, where Δf _max may represent the maximum supported subcarrier spacing, and N _f may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms) ) . Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023) .

Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on subcarrier spacing. Each slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . In some wireless communications systems 100, a slot may further be divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N _f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

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

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

Each base station 105 may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) , or others) . In some examples, a cell may also refer to a geographic coverage area 110 or a portion of a geographic coverage area 110 (e.g., a sector) over which the logical communication entity operates. Such cells may range from smaller areas (e.g., a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station 105. For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with geographic coverage areas 110, among other examples.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs 115 with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered base station 105, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to the UEs 115 with service subscriptions with the network provider or may provide restricted access to the UEs 115 having an association with the small cell (e.g., the UEs 115 in a closed subscriber group (CSG) , the UEs 115 associated with users in a home or office) . A base station 105 may support one or multiple cells and may also support communications over the one or more cells using one or multiple component carriers.

In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT) , enhanced mobile broadband (eMBB) ) that may provide access for different types of devices.

In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, the overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

The wireless communications system 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timings, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timings, and transmissions from different base stations 105 may, in some examples, not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that makes use of the information or presents the information to humans interacting with the application program. Some UEs 115 may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for the UEs 115 include entering a power saving deep sleep mode when not engaging in active communications, operating over a limited bandwidth (e.g., according to narrowband communications) , or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a defined portion or range (e.g., set of subcarriers or resource blocks (RBs) ) within a carrier, within a guard-band of a carrier, or outside of a carrier.

The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC) or mission critical communications. The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission critical functions) . Ultra-reliable communications may include private communication or group communication and may be supported by one or more mission critical services such as mission critical push-to-talk (MCPTT) , mission critical video (MCVideo) , or mission critical data (MCData) . Support for mission critical functions may include prioritization of services, and mission critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission critical, and ultra-reliable low-latency may be used interchangeably herein.

In some examples, a UE 115 may also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol) . One or more UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105 or be otherwise unable to receive transmissions from a base station 105. In some examples, groups of the UEs 115 communicating via D2D communications may utilize a one-to-many (1: M) system in which each UE 115 transmits to every other UE 115 in the group. In some examples, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between the UEs 115 without the involvement of a base station 105.

In some systems, the D2D communication link 135 may be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs 115) . In some examples, vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., base stations 105) using vehicle-to-network (V2N) communications, or with both.

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or 5G core (5GC) , which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management function (AMF) ) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the base stations 105 associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to the network operators IP services 150. The operators IP services 150 may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched Streaming Service.

Some of the network devices, such as a base station 105, may include subcomponents such as an access network entity 140, which may be an example of an access node controller (ANC) . Each access network entity 140 may communicate with the UEs 115 through one or more other access network transmission entities 145, which may be referred to as radio heads, smart radio heads, or transmission/reception points (TRPs) . Each access network transmission entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station 105) .

The wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. The UHF waves may be blocked or redirected by buildings and environmental features, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. The transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band, or in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, the wireless communications system 100 may support millimeter wave (mmW) communications between the UEs 115 and the base stations 105, and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

The wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, devices such as the base stations 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

A base station 105 or a UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for a signal transmitted via an antenna port.

The base stations 105 or the UEs 115 may use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords) . Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) , where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) , where multiple spatial layers are transmitted to multiple devices.

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

A base station 105 or a UE 115 may use beam sweeping techniques as part of beam forming operations. For example, a base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to conduct beamforming operations for directional communications with a UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions. For example, the base station 105 may transmit a signal according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by a transmitting device, such as a base station 105, or by a receiving device, such as a UE 115) a beam direction for later transmission or reception by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based on a signal that was transmitted in one or more beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions and may report to the base station 105 an indication of the signal that the UE 115 received with a highest signal quality or an otherwise acceptable signal quality.

In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from a base station 105 to a UE 115) . The UE 115 may report feedback that indicates precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across a system bandwidth or one or more sub-bands. The base station 105 may transmit a reference signal (e.g., a cell-specific reference signal (CRS) , a channel state information reference signal (CSI-RS) ) , which may be precoded or unprecoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook) . Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) or for transmitting a signal in a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115) may try multiple receive configurations (e.g., directional listening) when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive configurations or receive directions. In some examples, a receiving device may use a single receive configuration to receive along a single beam direction (e.g., when receiving a data signal) . The single receive configuration may be aligned in a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR) , or otherwise acceptable signal quality based on listening according to multiple beam directions) .

The wireless communications system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or a core network 130 supporting radio bearers for user plane data. At the physical layer, transport channels may be mapped to physical channels.

The UEs 115 and the base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions) . In some examples, a device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

In some cases, UE 115 may be a dual-SIM device. If both SIMs of a UE 115 are subscribed to the same operator, then each SIM may share frequency information that may be used for efficient registration by the other SIM. For example, a first SIM (e.g., SIM1) may register to the network and share the frequency used for registration with a second SIM (e.g., SIM2) to optimize the registration speed of the SIM2. Specifically, a shared frequency search may be performed at the SIM2 based on the frequency information from the SIM1. In some examples, the shared frequency search includes SIM2 searching the one frequency used to connect to the network by the SIM1. The SIM2 may search the shared frequency before an ACQ DB or full band scan is performed. With the shared frequency from the SIM1, there may be a high probability that the SIM2 may access network service as the SIM1 already camped to the frequency successfully.

If the SIM2 is unable to connect to the network via the shared frequency, the SIM2 may attempt an ACQ DB scan. An ACQ DB scan may include a limited list of frequencies (e.g., ten frequencies) that were previously used by the SIM2 that successfully connected to the network. In some cases, the ACQ DB may be empty or expired. If the ACQ DB scan is also unsuccessful, then the SIM2 may attempt a full band scan. A full band scan may include searching all frequencies in one or more frequency bands. Thus, if the SIM2 is able to register and connect to the network using the shared frequency, the additional frequency scans may be avoided, which may save time during the registration procedure and improve UE 115 communication quality.

FIG. 2 illustrates an example of a wireless communications system 200 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100. Wireless communications system 200 may include UE 115-a and base station 105-a, which may be respective examples of a UE 115 and a base station 105, as described with reference to FIG. 1.

UE 115-a may be a dual-SIM device including SIM1 215 and SIM2 220. UE 115-a may operate in dual-SIM single standby (passive) mode, dual-SIM dual active mode, or dual-SIM dual standby mode. SIM1 215 and SIM2 220 may belong to the same network operator. UEs 115-a is not limited to two SIMs and may include more SIMs (not shown) . In some cases, each SIM may support stand-alone operation on 5G carriers, that is UE 115-a may be a 5G+5G dual-SIM device.

In wireless communications system 200, each of SIM1 215 and SIM2 220 may register with the network via base station 105-a or base station 105-b. Each of SIM1 215 and SIM2 220 may undergo a separate registration procedure with base station 105-a or base station 105-b to access the network for future communications. For example, a SIM1 215 registration procedure may begin with a random access procedure where SIM1 215 may search a number of frequencies for synchronization signals 210 (e.g., an SSB) from a base station 105. For example, SIM1 215 may search an ACQ DB 225 that includes a list of N previously used frequencies for previous registration of SIM1 215. Additionally or alternatively, SIM1 215 may perform a full band scan, for example searching a raster of frequencies for the synchronization signals. The raster may include greater than N frequencies. In some cases, registration speed may incur a large latency from the multiple frequencies scanned. Also, delay in the search may be a result of the synchronization signals not being located at the center of the frequency of the carrier, which may decrease the raster increments. This may be the case for 5G (e.g., New Radio (NR) ) networks.

After the frequency of the synchronization signals 210-a is found, SIM1 215 may proceed through the random access and registration procedure for connecting to the base station 105-a. SIM2 220 may also undergo a registration procedure after SIM1 215. In some cases, SIM2 220 registration may conventionally use a full band scan for SIM2 220 when SIM2 220 is inserted into UE 115-a for the first time, when UE 115-a was roaming and at least SIM2 220 was out of service, or any other case that the SIM2 220 ACQ DB 230 is empty or outdated. Alternatively, the registration process for SIM 2 may use ACQ DB 230 (e.g., if populated) , prior to the full band scan. If SIM1 215 and SIM2 220 belong to the same network operator, when SIM1 receives normal service under a network (e.g., a 5GNR standalone network) , the registration of SIM2 220 may be optimized. To reduce latency during the registration of SIM2 220, SIM1 215 may share the frequency used for registration of SIM1 215 with SIM2 220.

For example, after SIM1 215 has already registered to the network via base station 105-a, SIM1 215 may share the current serving cell frequency with SIM2 220. In some cases, SIM1 215 may share the frequency with SIM2 220 by storing an indication of the current serving cell frequency in a shared location 235 (e.g., F _S) accessible by both SIM1 215 and SIM2 220. When SIM2 220 receives a service request from the NAS, SIM2 220 may scan the shared current serving cell frequency F _S 230 before any other frequency scans (e.g., an ACQ DB scan or full band scan) based on determining that SIM1 215 and SIM2 220 belong to the same operator. An exemplary network search sequence of SIM2 220 may begin with the shared frequency F _S 230. If registration of SIM2 220 is unsuccessful on the shared frequency, SIM2 220 may scan the ACQ DB. If registration of SIM2 220 is unsuccessful after the ACQ DB scan (e.g., if the ACQ DB is empty or expired) , SIM2 220 may perform a full band scan.

There is a high likelihood for SIM2 220 to get normal network service on the shared frequency based on SIM2 220 already connecting to the shared frequency successfully. As a result, the registration speed of SIM2 220 using the shared frequency may be faster than the registration speed of SIM2 220 using the ACQ DB 230 scan or full band scan as SIM2 220 may only search one frequency. Thus, UE 115-a may get network service or recover network service from an out of service operation faster than using the ACQ DB scan or full band scan. This may improve the UE 115-a power consumption as the number of frequencies scanned is reduced. In some cases, both SIM1 215 and SIM2 220 may store the frequency (e.g., frequency of the synchronization signals) of a most recent successfully acquired carrier in a shared location F _S 230. Thus, either or both of SIM1 215 and SIM2 220 may read from and write to the shared location F _S 230, enabling sharing to be for frequencies successfully acquired by SIM1 215 prior to SIM2 220, or acquired by SIM2 220 prior to SIM1 215. For example, if SIM2 220 acquires the synchronization signals 210-b of a different carrier 205-b (e.g., which may be the same or a different carrier frequency) , SIM2 220 may overwrite shared location F _S 230.

FIG. 3 illustrates an example of a flowchart 300 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. In some examples, flowchart 300 may implement aspects of wireless communications system 100. Flowchart 300 includes a frequency sharing procedure at a SIM1 305 and a registration procedure at SIM2 310. SIM1 305 and SIM2 310 may be in a dual-SIM UE and be examples of SIM1 215 and SIM2 220, respectively, as described in FIG. 2. SIM1 305 may be associated with a subscription (SUB) to a network, such as SUB1. Similarly, SIM2 310 may be associated with SUB2.

The frequency sharing procedure at SIM1 305 may include

blocks

315 and 320. At 315, SIM1 may register to the network (e.g., an NR standalone network) according to SUB1 on a serving cell frequency. At 320, SIM1 may share the current serving cell frequency to SIM2, for example, by storing the serving cell frequency in a shared location that is accessible by both SIM1 and SIM2.

The registration procedure at SIM2 310 may include blocks 325 through 350. At 325, SIM2 may start to search for the network. At 330, SIM2 may determine if SUB2 belongs to the same operator as SUB1. If SUB1 and SUB2 belong to the same operator, SIM2 proceeds to block 335. If SUB1 and SUB2 belong to different operators, SIM2 proceeds to block 345.

At 335, SIM2 may scan the shared frequency from SIM1 stored in the shared location. At 340, SIM2 may determine if registration to cell on the shared frequency is successful. If registration to cell on the shared frequency is successful, SIM2 proceeds to 350. If registration to cell on the shared frequency is unsuccessful, SIM2 proceeds to 345.

At 345, SIM2 may perform an ACQ DB if the ACQ DB is not empty. If registration to a cell on one of the ACQ DB frequencies is successful, SIM2 proceeds to 350. If the ACQ DB is empty or expired such that SIM2 registration to cells on all ACQ DB frequencies is unsuccessful, SIM2 may perform a full band scan to find and register with a cell and proceed to 350. At 350, SIM2 successfully registers to the network and completes the registration procedure according to SUB2.

FIG. 4 illustrates an example of a process flow 400 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. In some examples, process flow 400 may implement aspects of wireless communications system 100. Process flow 400 is shown as being implemented by a UE 115-b, which may be an example of the UEs 115 as described with respect to FIGs. 1 and 2. For example, UE 115-b may be an example of UE 115-a of FIG. 2. Process flow 400 is also shown as being implemented by base station 105-c, which may be an example of the base stations 105 as described with respect to FIGs. 1 and 2. For example, base station 105-c may be an example of base station 105-a or base station 105-b of FIG. 2.

In the following description of the process flow 400, the operations of UE 115-b and base station 105-c may occur in a different order than the exemplary order shown. Certain illustrated operations may also be left out of the process flow 400, or other operations may be added to the process flow 400. It is to be understood that while UE 115-b and base station 105-b are shown performing a number of the operations of process flow 400, any wireless device may perform the operations shown.

At 405, base station 105-c may transmit and UE 115-b may receive an SSB on a first synchronization signal frequency. In some examples, the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier.

At 410, UE 115-b may register SIM1 of the UE 115-b to a network on a carrier having a first synchronization signal frequency, where using the first synchronization signal frequency for registration may be based on receiving the SSB at 405.

At 415, UE 115-b may store, based on registering the SIM1 of the UE 115-b to the network on the carrier at 410, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the SIM2. In some cases, UE 115-b (e.g., SIM1 and SIM2) may determine that the SIM1 and the SIM2 are associated with a same operator, where storing the first synchronization signal frequency may be based on this determination.

At 420, UE 115-b may identify a trigger to register SIM2 of the UE 115-b. For example, SIM2 may identify an indicator to recover network service after being out of service, UE 115-b may identify an indicator of a presence of the second subscriber identity module, or SIM2 may identify a roaming mode for registering the SIM2 of the UE 115-b.

At 425, UE 115-b may search for a synchronization signal (e.g., an SSB at 430) of the carrier on the first synchronization signal frequency for registering the SIM2 of the UE 115-b to the network on the carrier. In some cases, searching for the synchronization signal of the carrier on the first synchronization signal frequency is based on determining that the SIM1 and the SIM2 are associated with a same operator.

At 430, base station 105-c may transmit and UE 115-b may receive an SSB such that SIM2 acquires the synchronization signal of the carrier based on the searching.

At 435, UE 115-b may register the second subscriber identity module to the network on the carrier based on acquiring the synchronization signal. In some examples, the synchronization signal is acquired on the shared frequency after a limited search of that frequency. In other examples, if the SIM2 does not successfully acquire the SSB on the shared frequency, SIM2 may scan an ACQ DB for registering the SIM2 of the UE 115-b to one or more networks based on an unsuccessful registration to the carrier. In other examples, if the SIM2 does not successfully acquire the SSB on a frequency from the ACQ DB, SIM2 may scan one or more frequency bands according to a raster for registering the SIM2 of the UE 115-b to one or more networks based on completing the scanning of the ACQ DB without successfully registering the SIM2 of the UE 115-b. For example, the ACQ DB may be empty or expired. Once SIM2 is registered to the network, SIM2 may communicate with the network.

FIG. 5 shows a block diagram 500 of a device 505 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a communications manager 515, and a transmitter 520. The device 505 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to SIM registration in dual-SIM device, etc. ) . Information may be passed on to other components of the device 505. The receiver 510 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The receiver 510 may utilize a single antenna or a set of antennas.

The communications manager 515 may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identify a trigger to register a second subscriber identity module of the UE, and search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The communications manager 515 may be an example of aspects of the communications manager 810 described herein.

The communications manager 515, or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 515, or its sub-components may be executed by a general-purpose processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field programable 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 in the present disclosure.

The communications manager 515, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the communications manager 515, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 515, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 520 may transmit signals generated by other components of the device 505. In some examples, the transmitter 520 may be collocated with a receiver 510 in a transceiver module. For example, the transmitter 520 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The transmitter 520 may utilize a single antenna or a set of antennas.

FIG. 6 shows a block diagram 600 of a device 605 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The device 605 may be an example of aspects of a device 505, or a UE 115 as described herein. The device 605 may include a receiver 610, a communications manager 615, and a transmitter 635. The device 605 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to SIM registration in dual-SIM device, etc. ) . Information may be passed on to other components of the device 605. The receiver 610 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The receiver 610 may utilize a single antenna or a set of antennas.

The communications manager 615 may be an example of aspects of the communications manager 515 as described herein. The communications manager 615 may include a SIM1 registration manager 620, a SIM2 trigger identifier 625, and a SIM2 synchronization component 630. The communications manager 615 may be an example of aspects of the communications manager 810 described herein.

The SIM1 registration manager 620 may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The SIM2 trigger identifier 625 may identify a trigger to register a second subscriber identity module of the UE. The SIM2 synchronization component 630 may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

The transmitter 635 may transmit signals generated by other components of the device 605. In some examples, the transmitter 635 may be collocated with a receiver 610 in a transceiver module. For example, the transmitter 635 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The transmitter 635 may utilize a single antenna or a set of antennas.

FIG. 7 shows a block diagram 700 of a communications manager 705 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The communications manager 705 may be an example of aspects of a communications manager 515, a communications manager 615, or a communications manager 810 described herein. The communications manager 705 may include a SIM1 registration manager 710, a SIM2 trigger identifier 715, a SIM2 synchronization component 720, an operator manager 725, a SIM2 acquisition component 730, a SIM2 registration manager 735, a database controller 740, a SIM2 acquisition database scanner 745, and a SIM2 frequency band scanner 750. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The SIM1 registration manager 710 may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. In some cases, the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier. In some cases, the first subscriber identity module is associated with a first subscriber and the second subscriber identity module is associated with a second subscriber. In some cases, the first subscriber and the second subscriber are configured to communicate on carriers of the network configured for standalone registration of the UE.

The SIM2 trigger identifier 715 may identify a trigger to register a second subscriber identity module of the UE. In some examples, the SIM2 trigger identifier 715 may identify an indicator to recover network service after being out of service. In some examples, the SIM2 trigger identifier 715 may identify an indicator of a presence of the second subscriber identity module. In some examples, the SIM2 trigger identifier 715 may identify a roaming mode for registering the second subscriber identity module of the UE.

The SIM2 synchronization component 720 may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

The operator manager 725 may determine that the first subscriber identity module and the second subscriber identity module are associated with a same operator, where searching for the synchronization signal of the carrier on the first synchronization signal frequency is based on the determining.

The SIM2 acquisition component 730 may acquire the synchronization signal of the carrier based on the searching.

The SIM2 registration manager 735 may register the second subscriber identity module to the network on the carrier based on acquiring the synchronization signal.

The database controller 740 may store, based on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.

The SIM2 acquisition database scanner 745 may scan an acquisition database for registering the second subscriber identity module of the UE to one or more networks based on an unsuccessful registration to the carrier.

The SIM2 frequency band scanner 750 may scan one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.

FIG. 8 shows a diagram of a system 800 including a device 805 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The device 805 may be an example of or include the components of device 505, device 605, or a UE 115 as described herein. The device 805 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 810, an I/O controller 815, a transceiver 820, an antenna 825, memory 830, and a processor 840. These components may be in electronic communication via one or more buses (e.g., bus 845) .

The communications manager 810 may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency, identify a trigger to register a second subscriber identity module of the UE, and search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.

The I/O controller 815 may manage input and output signals for the device 805. The I/O controller 815 may also manage peripherals not integrated into the device 805. In some cases, the I/O controller 815 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 815 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 815 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 815 may be implemented as part of a processor. In some cases, a user may interact with the device 805 via the I/O controller 815 or via hardware components controlled by the I/O controller 815.

The transceiver 820 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described herein. For example, the transceiver 820 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 820 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 825. However, in some cases the device may have more than one antenna 825, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 830 may include RAM and ROM. The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 830 may contain, among other things, a basic input/output system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 840 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks supporting SIM registration in dual-SIM device) .

The code 835 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 835 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 835 may not be directly executable by the processor 840 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 9 shows a flowchart illustrating a method 900 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 900 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 900 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 905, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 905 may be performed according to the methods described herein. In some examples, aspects of the operations of 905 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 910, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 910 may be performed according to the methods described herein. In some examples, aspects of the operations of 910 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 915, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 915 may be performed according to the methods described herein. In some examples, aspects of the operations of 915 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

FIG. 10 shows a flowchart illustrating a method 1000 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 1000 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1000 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1005, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 1005 may be performed according to the methods described herein. In some examples, aspects of the operations of 1005 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 1010, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 1010 may be performed according to the methods described herein. In some examples, aspects of the operations of 1010 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 1015, the UE may determine that the first subscriber identity module and the second subscriber identity module are associated with a same operator, where searching for the synchronization signal of the carrier on the first synchronization signal frequency is based on the determining. The operations of 1015 may be performed according to the methods described herein. In some examples, aspects of the operations of 1015 may be performed by an operator manager as described with reference to FIGs. 5 through 8.

At 1020, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 1020 may be performed according to the methods described herein. In some examples, aspects of the operations of 1020 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

FIG. 11 shows a flowchart illustrating a method 1100 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 1100 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1100 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1105, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 1105 may be performed according to the methods described herein. In some examples, aspects of the operations of 1105 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 1110, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 1110 may be performed according to the methods described herein. In some examples, aspects of the operations of 1110 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 1115, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 1115 may be performed according to the methods described herein. In some examples, aspects of the operations of 1115 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

At 1120, the UE may acquire the synchronization signal of the carrier based on the searching. The operations of 1120 may be performed according to the methods described herein. In some examples, aspects of the operations of 1120 may be performed by a SIM2 acquisition component as described with reference to FIGs. 5 through 8.

At 1125, the UE may register the second subscriber identity module to the network on the carrier based on acquiring the synchronization signal. The operations of 1125 may be performed according to the methods described herein. In some examples, aspects of the operations of 1125 may be performed by a SIM2 registration manager as described with reference to FIGs. 5 through 8.

FIG. 12 shows a flowchart illustrating a method 1200 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 1200 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1200 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1205, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 1205 may be performed according to the methods described herein. In some examples, aspects of the operations of 1205 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 1210, the UE may store, based on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module. The operations of 1210 may be performed according to the methods described herein. In some examples, aspects of the operations of 1210 may be performed by a database controller as described with reference to FIGs. 5 through 8.

At 1215, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 1215 may be performed according to the methods described herein. In some examples, aspects of the operations of 1215 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 1220, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 1220 may be performed according to the methods described herein. In some examples, aspects of the operations of 1220 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

FIG. 13 shows a flowchart illustrating a method 1300 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 1300 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1300 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1305, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 1305 may be performed according to the methods described herein. In some examples, aspects of the operations of 1305 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 1310, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 1310 may be performed according to the methods described herein. In some examples, aspects of the operations of 1310 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 1315, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 1315 may be performed according to the methods described herein. In some examples, aspects of the operations of 1315 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

At 1320, the UE may scan an acquisition database for registering the second subscriber identity module of the UE to one or more networks based on an unsuccessful registration to the carrier. The operations of 1320 may be performed according to the methods described herein. In some examples, aspects of the operations of 1320 may be performed by a SIM2 acquisition database scanner as described with reference to FIGs. 5 through 8.

FIG. 14 shows a flowchart illustrating a method 1400 that supports SIM registration in dual-SIM device in accordance with aspects of the present disclosure. The operations of method 1400 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1400 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1405, the UE may register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency. The operations of 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be performed by a SIM1 registration manager as described with reference to FIGs. 5 through 8.

At 1410, the UE may identify a trigger to register a second subscriber identity module of the UE. The operations of 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed by a SIM2 trigger identifier as described with reference to FIGs. 5 through 8.

At 1415, the UE may search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier. The operations of 1415 may be performed according to the methods described herein. In some examples, aspects of the operations of 1415 may be performed by a SIM2 synchronization component as described with reference to FIGs. 5 through 8.

At 1420, the UE may scan an acquisition database for registering the second subscriber identity module of the UE to one or more networks based on an unsuccessful registration to the carrier. The operations of 1420 may be performed according to the methods described herein. In some examples, aspects of the operations of 1420 may be performed by a SIM2 acquisition database scanner as described with reference to FIGs. 5 through 8.

At 1425, the UE may scan one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE. The operations of 1425 may be performed according to the methods described herein. In some examples, aspects of the operations of 1425 may be performed by a SIM2 frequency band scanner as described with reference to FIGs. 5 through 8.

It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an 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 processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

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

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM) , read-only memory (ROM) , electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include 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 computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communications at a user equipment (UE) , comprising:

registering a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency;

identifying a trigger to register a second subscriber identity module of the UE; and

searching for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.
The method of claim 1, further comprising:

determining that the first subscriber identity module and the second subscriber identity module are associated with a same operator, wherein searching for the synchronization signal of the carrier on the first synchronization signal frequency is based at least in part on the determining.
The method of claim 1, further comprising:

acquiring the synchronization signal of the carrier based at least in part on the searching; and

registering the second subscriber identity module to the network on the carrier based at least in part on acquiring the synchronization signal.
The method of claim 1, further comprising:

storing, based at least in part on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.
The method of claim 1, wherein identifying the trigger to register the second subscriber identity module of the UE comprises:

identifying an indicator to recover network service after being out of service.
The method of claim 1, wherein identifying the trigger to register the second subscriber identity module of the UE comprises:

identifying an indicator of a presence of the second subscriber identity module.
The method of claim 1, wherein identifying the trigger to register the second subscriber identity module of the UE comprises:

identifying a roaming mode for registering the second subscriber identity module of the UE.
The method of claim 1, wherein the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier.
The method of claim 1, further comprising:

scanning an acquisition database for registering the second subscriber identity module of the UE to one or more networks based at least in part on an unsuccessful registration to the carrier.
The method of claim 9, further comprising:

scanning one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based at least in part on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.
The method of claim 1, wherein the first subscriber identity module is associated with a first subscriber and the second subscriber identity module is associated with a second subscriber.
The method of claim 11, wherein the first subscriber and the second subscriber are configured to communicate on carriers of the network configured for standalone registration of the UE.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency;

identify a trigger to register a second subscriber identity module of the UE; and

search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

determine that the first subscriber identity module and the second subscriber identity module are associated with a same operator, wherein searching for the synchronization signal of the carrier on the first synchronization signal frequency is based at least in part on the determining.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

acquire the synchronization signal of the carrier based at least in part on the searching; and

register the second subscriber identity module to the network on the carrier based at least in part on acquiring the synchronization signal.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

store, based at least in part on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.
The apparatus of claim 13, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable by the processor to cause the apparatus to:

identify an indicator to recover network service after being out of service.
The apparatus of claim 13, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable by the processor to cause the apparatus to:

identify an indicator of a presence of the second subscriber identity module.
The apparatus of claim 13, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable by the processor to cause the apparatus to:

identify a roaming mode for registering the second subscriber identity module of the UE.
The apparatus of claim 13, wherein the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

scan an acquisition database for registering the second subscriber identity module of the UE to one or more networks based at least in part on an unsuccessful registration to the carrier.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

scan one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based at least in part on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.
The apparatus of claim 13, wherein the first subscriber identity module is associated with a first subscriber and the second subscriber identity module is associated with a second subscriber.
The apparatus of claim 23, wherein the first subscriber and the second subscriber are configured to communicate on carriers of the network configured for standalone registration of the UE.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for registering a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency;

means for identifying a trigger to register a second subscriber identity module of the UE; and

means for searching for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.
The apparatus of claim 25, further comprising:

means for determining that the first subscriber identity module and the second subscriber identity module are associated with a same operator, wherein searching for the synchronization signal of the carrier on the first synchronization signal frequency is based at least in part on the determining.
The apparatus of claim 25, further comprising:

means for acquiring the synchronization signal of the carrier based at least in part on the searching; and

means for registering the second subscriber identity module to the network on the carrier based at least in part on acquiring the synchronization signal.
The apparatus of claim 25, further comprising:

means for storing, based at least in part on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.
The apparatus of claim 25, wherein the means for identifying the trigger to register the second subscriber identity module of the UE comprises:

means for identifying an indicator to recover network service after being out of service.
The apparatus of claim 25, wherein the means for identifying the trigger to register the second subscriber identity module of the UE comprises:

means for identifying an indicator of a presence of the second subscriber identity module.
The apparatus of claim 25, wherein the means for identifying the trigger to register the second subscriber identity module of the UE comprises:

means for identifying a roaming mode for registering the second subscriber identity module of the UE.
The apparatus of claim 25, wherein the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier.
The apparatus of claim 25, further comprising:

means for scanning an acquisition database for registering the second subscriber identity module of the UE to one or more networks based at least in part on an unsuccessful registration to the carrier.
The apparatus of claim 33, further comprising:

means for scanning one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based at least in part on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.
The apparatus of claim 25, wherein the first subscriber identity module is associated with a first subscriber and the second subscriber identity module is associated with a second subscriber.
The apparatus of claim 35, wherein the first subscriber and the second subscriber are configured to communicate on carriers of the network configured for standalone registration of the UE.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

register a first subscriber identity module of the UE to a network on a carrier having a first synchronization signal frequency;

identify a trigger to register a second subscriber identity module of the UE; and

search for a synchronization signal of the carrier on the first synchronization signal frequency for registering the second subscriber identity module of the UE to the network on the carrier.
The non-transitory computer-readable medium of claim 37, wherein the instructions are further executable to:

determine that the first subscriber identity module and the second subscriber identity module are associated with a same operator, wherein searching for the synchronization signal of the carrier on the first synchronization signal frequency is based at least in part on the determining.
The non-transitory computer-readable medium of claim 37, wherein the instructions are further executable to:

acquire the synchronization signal of the carrier based at least in part on the searching; and

register the second subscriber identity module to the network on the carrier based at least in part on acquiring the synchronization signal.
The non-transitory computer-readable medium of claim 37, wherein the instructions are further executable to:

store, based at least in part on registering the first subscriber identity module of the UE to the network on the carrier, the first synchronization signal frequency in a shared frequency database configured to be accessed for registering the second subscriber identity module.
The non-transitory computer-readable medium of claim 37, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable to:

identify an indicator to recover network service after being out of service.
The non-transitory computer-readable medium of claim 37, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable to:

identify an indicator of a presence of the second subscriber identity module.
The non-transitory computer-readable medium of claim 37, wherein the instructions to identify the trigger to register the second subscriber identity module of the UE are executable to:

identify a roaming mode for registering the second subscriber identity module of the UE.
The non-transitory computer-readable medium of claim 37, wherein the first synchronization signal frequency is located at a frequency offset from a center frequency of the carrier.
The non-transitory computer-readable medium of claim 37, wherein the instructions are further executable to:

scan an acquisition database for registering the second subscriber identity module of the UE to one or more networks based at least in part on an unsuccessful registration to the carrier.
The non-transitory computer-readable medium of claim 45, wherein the instructions are further executable to:

scan one or more frequency bands according to a raster for registering the second subscriber identity module of the UE to one or more networks based at least in part on completing the scanning of the acquisition database without successfully registering the second subscriber identity module of the UE.
The non-transitory computer-readable medium of claim 37, wherein the first subscriber identity module is associated with a first subscriber and the second subscriber identity module is associated with a second subscriber.
The non-transitory computer-readable medium of claim 47, wherein the first subscriber and the second subscriber are configured to communicate on carriers of the network configured for standalone registration of the UE.