WO2021258281A1

WO2021258281A1 - Timer based network switching to support voice services

Info

Publication number: WO2021258281A1
Application number: PCT/CN2020/097649
Authority: WO
Inventors: Haibo Liu; Bing LENG; Hao Zhang; Xiaomeng Lu; Jian Li
Original assignee: Qualcomm Incorporated
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2021-12-30

Abstract

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may establish a connection with a first network. A registration message may be transmitted to a second network for establishing voice over internet protocol services with the second network. A registration failure message may be received from the second network, where the registration failure message indicates a retry timer for retrying registration with the second network. A determination may be made that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and a search procedure for a third network may be performed for switching the connection from the first network to the third network.

Description

TIMER BASED NETWORK SWITCHING TO SUPPORT VOICE SERVICES

FIELD OF TECHNOLOGY

The following relates generally to wireless communications and more specifically to timer based network switching to support voice services.

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 attempt to register with a network to obtain services (e.g., voice over internet protocol functionality) . In some cases, the UE may experience a registration failure for one or more reasons. The UE may reattempt to successfully register with the network upon expiration of a retry timer, however, during the duration of the retry timer the UE may lack some services or capabilities (e.g., voice capability) .

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support timer based network switching to support voice services. Generally, the described techniques provide for switching between networks or radio access technologies based on a retry timer exceeding a timer threshold to reduce latency among other benefits. For example, a user equipment (UE) may establish a connection with a first network. The UE may transmit a registration message to a second network for establishing the voice over internet protocol services. The UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. The UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. The UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and at circuit switched fallback is unsupported.

A method of wireless communications at a UE is described. The method may include establishing a connection with a first network, transmitting a registration message to a second network for establishing voice over internet protocol services, receiving a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determining that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and performing a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

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 establish a connection with a first network, transmit a registration message to a second network for establishing voice over internet protocol services, receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for establishing a connection with a first network, transmitting a registration message to a second network for establishing voice over internet protocol services, receiving a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determining that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and performing a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

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 establish a connection with a first network, transmit a registration message to a second network for establishing voice over internet protocol services, receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for switching the connection from the first network to the third network based at least in part performing the search procedure for the third network.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for maintaining the connection with the third network for a duration of the retry timer.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for establishing a voice connection with the third network based on switching the connection from the first network to the third network.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for performing a search procedure for the first network upon expiration of the retry timer for switching the connection from the third network to the first network.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving configuration signaling indicating the time threshold for the UE.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining, by the UE, the time threshold for the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second network includes an internet protocol multimedia subsystem network, and the third network includes a legacy network with respect to the first network.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the UE includes a subscriber identification module that does not support voice over internet protocol services for the first network.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for establishing a connection with a fourth network after establishing the connection with the first network and before transmitting the registration message to the second network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communications that supports timer based network switching to support voice services in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a process flow that supports timer based network switching to support voice services in accordance with aspects of the present disclosure.

FIGs. 3 and 4 show block diagrams of devices that support timer based network switching to support voice services in accordance with aspects of the present disclosure.

FIG. 5 shows a block diagram of a communications manager that supports timer based network switching to support voice services in accordance with aspects of the present disclosure.

FIG. 6 shows a diagram of a system including a device that supports timer based network switching to support voice services in accordance with aspects of the present disclosure.

FIGs. 7 through 11 show flowcharts illustrating methods that support timer based network switching to support voice services in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Wireless communications systems may support communications between a user equipment (UE) and a base station. The UE and the base station may communicate over one or more networks or radio access technologies, such as a long-term evolution (LTE) network, a new radio (NR) non-standalone (NSA) network, one or more legacy networks, an internet protocol multimedia subsystem (IMS) network, among other examples. In some cases, following successful attachment by a UE with the LTE and NR NSA networks, the UE may attempt IMS registration. However, in some cases, IMS registration may fail because of one or more issues associated with one or more of the networks, and a session initiated protocol (SIP) failure response including a retry-after header may be sent in response to the failure of the IMS registration. The retry-after header may include or otherwise indicate a retry timer. The UE may retry to complete a successful connection with the IMS network upon expiration of the retry timer. During such a timer period, the UE may remain connected to the LTE or NSA networks. Additionally, during this time period, if circuit switched fallback (CSFB) mode for the UE and the corresponding LTE or NSA networks is not available or unsupported, the UE may not have voice capability during this time. In such examples, following a failure event as described herein, and after a time period associated with the retry-after timer has passed, the UE may remain on the LTE or NSA networks and begin an additional retry-after timer. The UE may continue retrying to successfully complete IMS registration while remaining on the LTE or NSA networks.

In the examples described herein, to facilitate maintaining voice capability of the UE during attempted IMS network registration, the UE may utilize a connection with one or more legacy networks (as compared to the LTE or NR NSA network) to maintain a voice capability of the UE. In such examples, the UE receives a retry-after timer from one or more of the networks. The UE may define a threshold timer and may determine whether the received retry-after timer exceeds the defined threshold timer. The UE may also determine whether CSFB is supported by the UE or the network that the UE is currently connected with. If the retry-after timer exceeds the threshold timer and CSFB is unsupported, then the UE may conduct a search for one or more legacy networks, or RATs, to obtain voice capability during the duration of the retry-after timer. The legacy networks may include one or more of a GSM network, a CDMA network, or a WCDMA network.

In such examples, the UE may remain connected to one or more of the legacy networks to maintain voice capability. Following expiration of the retry-after timer, the UE may establish a connection with the LTE or NSA networks and may initiate IMS registration again.

Particular aspects of the subject matter described herein may be implemented to realize one or more potential advantages. The described techniques may provide for efficient maintenance of a voice functionality of a UE operating on one or more wireless networks while the UE is searching for and attempting connection with one or more networks, such as the IMS network. As such, the UE may improve a user experience for a user of the UE as the user is able to have continuity of voice functionality while transitioning throughout various network areas.

Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are described in the context of retry timers defining periods of time for which a UE may attempt to connect to a network, various wireless networks including LTE, NSA, IMS and legacy networks, and methods for facilitating maintenance of a voice connection during the duration of time that the UE is attempting to connect to the one or more desired networks. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to timer based network switching to support voice services.

FIG. 1 illustrates an example of a wireless communications system 100 that supports timer based network switching to support voice services 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, following successful attachment by the UE 115 with the LTE and NR NSA networks, the UE 115 may start IMS registration. However, in some cases, IMS registration may fail because of one or more issues associated with one or more of the networks, and an SIP failure response including a retry-after header may be sent in response to the failure of the IMS registration. The UE 115 may retry to complete a successful connection with the IMS upon expiration of a retry timer indicated in the retry-after header. During such a timer period, the UE 115 may remain connected to the LTE or NSA networks. Additionally, during this time period, if CSFB for the UE 115 and the corresponding LTE or NSA networks is not available, the UE 115 may not have voice capability. For example, this may occur if a SIM card or subscription for the UE 115 does not support voice services for the LTE or NSA networks (e.g., does not support VoLTE) , thereby requiring that the UE successfully register with the IMS network to perform a voice over IP (VoIP) call. In such examples, following a failure event as described herein, and after a time period associated with the retry-after timer has passed, the UE 115 may remain on the LTE or NSA networks and begin an additional retry-after timer. The UE 115 may continue retrying to successfully complete IMS registration while remaining on the LTE or NSA networks.

In the examples described herein, to facilitate maintaining voice capability of the UE 115 during attempted IMS network registration, the UE 115 may utilize a connection with one or more legacy networks (as compared to the LTE or NR NSA network) to maintain a voice capability of the UE 115. In such examples, the UE 115 may receive a retry-after timer from one or more of the networks. The UE 115 may define a threshold timer and may determine whether the received retry-after timer exceeds the defined threshold timer. The UE 115 may also determine whether CSFB is supported by the UE 115 or the LTE network. If the retry-after timer exceeds the threshold timer and CSFB is unsupported, then the UE 115 may disconnect from the LTE or NSA networks and may conduct a search for one or more legacy networks, or RATs, to obtain voice capability. The legacy networks may include one or more of a GSM network, a CDMA network, or a WCDMA network.

In such examples, the UE 115 may remain connected to one or more of the legacy networks to maintain voice capability. Following expiration of the retry-after timer, the UE 115 may establish a connection with the LTE or NSA networks and may initiate IMS registration again.

In one example, a UE 115 may be a user device that is capable of functioning on and interacting with the LTE or NSA networks. Additionally, an LTE cell, an NR NSA cell, a legacy network cell (or RAT) , and an IMS network may be available and within connection range of the UE 115. The UE 115 may be powered-on or the UE 115 may be brought to within a service area of the LTE cell, the NR NSA cell, the legacy network cell, and the IMS network such that the UE 115 may be attempting to connect to one or more of the networks to obtain voice and data service. The UE 115 may first successfully connect to the LTE and the NSA networks, and may then attempt to connect and register with the IMS network. However, for any number of reasons, registration with the IMS network by the UE 115 may fail.

Accordingly, the IMS network may transmit a message to the UE 115 that indicates a retry timer after which the UE 115 may retry to successfully register with the IMS network. During the period of time specified by the retry timer, the UE 115 may perform a search for one or more legacy networks to obtain services (e.g., voice services) . In this example, because one or more legacy networks are available, the UE 115 is able to connect to one or more of the legacy networks to maintain voice capability while attempting to obtain successful registration and connection with the IMS network. Accordingly, use of the retry time and connection with one or more legacy networks by the UE 115 facilitates efficient continuation of voice functionality of the UE 115 while the UE is attempting to obtain voice over internet protocol functionality without disrupting the voice service experience of a user associated with the UE 115.

FIG. 2 illustrates an example of a process flow 200 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. In some examples, the process flow 200 may implement aspects of wireless communication system 100. The process flow 200 may illustrate communication between a UE 210 and a base station associated with one or more networks (e.g.,

networks

205, 215, 220, or 225) , which may be examples of corresponding devices as described herein. The UE 210 or the base station, or both, may use timer based network switching to support voice services. Alternative examples of the following may be implemented, where some steps are performed in a different order than described or are not performed at all. In some cases, steps may include additional features not mentioned below, or further steps may be added.

The process flow 200 may include a third network 205, a UE 210, a first network 215, a second network 220, and a fourth network 225. The first network 215 may be an example of an LTE network. In some examples, the second network 220 may be an example of an internet protocol multimedia subsystem network (e.g., an IMS network) . In such cases, the third network 205 may include a legacy network with respect to the first network 215. In further examples, the UE 210 may include a subscriber identification module that does not support voice over internet protocol services for the first network 215.

At 230, the UE 210 may establish a connection with the first network 215.

At 235, the UE 210 may establish a connection with the fourth network 225 after establishing the connection with the first network 215. In some examples, the fourth network may be an example of a NR NSA network. In such cases, the connection with the fourth network 225 may be established after the UE 210 has established the connection with the first network 215 and before the UE 210 has transmitted a registration message to the second network 220.

At 240, the UE 210 may transmit a registration message to the second network 220 for establishing voice over internet protocol services with the second network 220. In some alternative examples, the transmission of the registration message may be based on voice over internet protocol services being unsupported by the UE 210 or the first network 215.

At 245, the UE 210 may receive a registration failure message from the second network 220. In such examples the registration failure message may indicate a retry timer for retrying a registration procedure with the second network 220.

At 250, the UE 210 may determine that the retry timer exceeds a time threshold for the UE 210. In some examples, UE 210 may also determine that circuit switched fallback is unsupported by the UE 210 or the first network 215.

At 255 the UE 210 may perform a search procedure for the third network 205 for switching the connection from the first network 215 to the third network 205 (e.g., to maintain or acquire voice services) . In such examples, performing the search procedure for the third network 205 for switching the connection from the first network 215 to the third network 205 may be based on determining that the retry timer exceeds the time threshold for the UE 210 and that circuit switched fallback is unsupported. In some examples, the UE 210 may perform a search procedure for the first network 215 following expiration of the retry timer. The UE 210 may receive configuration signaling that indicates the time threshold for the UE. In further cases, the UE 210 may determine the time threshold for the UE 210. If the UE 210 determines that the retry timer does not exceed the time threshold or that CSFB is supported, then the UE may stay on the first network 215 for the duration of the retry timer.

At 260, the UE 210 may switch connection from the first network 215 to the third network 205. For example, the UE 210 may perform attach procedures with the third network 205. In such examples switching the connection from the first network 215 to the third network 205 may be based on performing the search procedure for the third network 205. In some cases, the connection with the third network 205 may be maintained for a duration of the retry timer. In other cases, the UE 210 may establish a voice connection with the third network 205 based on switching the connection from the first network 215 to the third network 205. Upon expiration of the retry timer, the UE 210 may release its connection with the third network 205 and begin an attach procedure with the first network 215 and/or the forth network 225.

FIG. 3 shows a block diagram 300 of a device 305 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The device 305 may be an example of aspects of a UE 115 as described herein. The device 305 may include a receiver 310, a communications manager 315, and a transmitter 320. The device 305 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 310 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 timer based network switching to support voice services, etc. ) . Information may be passed on to other components of the device 305. The receiver 310 may be an example of aspects of the transceiver 620 described with reference to FIG. 6. The receiver 310 may utilize a single antenna or a set of antennas.

The communications manager 315 may establish a connection with a first network. The communications manager 315 may transmit a registration message to a second network. The communications manager 315 may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The communications manager 315 may be an example of aspects of the communications manager 610 described herein.

The communications manager 315, 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 315, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a 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 315, 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 315, 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 315, 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 320 may transmit signals generated by other components of the device 305. In some examples, the transmitter 320 may be collocated with a receiver 310 in a transceiver module. For example, the transmitter 320 may be an example of aspects of the transceiver 620 described with reference to FIG. 6. The transmitter 320 may utilize a single antenna or a set of antennas.

FIG. 4 shows a block diagram 400 of a device 405 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The device 405 may be an example of aspects of a device 305, or a UE 115 as described herein. The device 405 may include a receiver 410, a communications manager 415, and a transmitter 445. The device 405 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 410 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 timer based network switching to support voice services, etc. ) . Information may be passed on to other components of the device 405. The receiver 410 may be an example of aspects of the transceiver 620 described with reference to FIG. 6. The receiver 410 may utilize a single antenna or a set of antennas.

The communications manager 415 may be an example of aspects of the communications manager 315 as described herein. The communications manager 415 may include a connection component 420, a transmission component 425, a reception component 430, a threshold determination component 435, and a search component 440. The communications manager 415 may be an example of aspects of the communications manager 610 described herein.

The connection component 420 may establish a connection with a first network.

The transmission component 425 may transmit a registration message to a second network for establishing voice over internet protocol services.

The reception component 430 may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network.

The threshold determination component 435 may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network.

The search component 440 may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

The transmitter 445 may transmit signals generated by other components of the device 405. In some examples, the transmitter 445 may be collocated with a receiver 410 in a transceiver module. For example, the transmitter 445 may be an example of aspects of the transceiver 620 described with reference to FIG. 6. The transmitter 445 may utilize a single antenna or a set of antennas.

FIG. 5 shows a block diagram 500 of a communications manager 505 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The communications manager 505 may be an example of aspects of a communications manager 315, a communications manager 415, or a communications manager 610 described herein. The communications manager 505 may include a connection component 510, a transmission component 515, a reception component 520, a threshold determination component 525, a search component 530, and a switching component 535. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The connection component 510 may establish a connection with a first network.

In some examples, the connection component 510 may establish a connection with a fourth network after establishing the connection with the first network and before transmitting the registration message to the second network.

The transmission component 515 may transmit a registration message to a second network for establishing voice over internet protocol services.

The reception component 520 may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network.

In some examples, the reception component 520 may receive configuration signaling indicating the time threshold for the UE.

The threshold determination component 525 may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network.

In some examples, the threshold determination component 525 may determine, by the UE, the time threshold for the UE.

The search component 530 may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

The switching component 535 may switch the connection from the first network to the third network based at least in part on performing the search procedure for the third network.

FIG. 6 shows a diagram of a system 600 including a device 605 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The device 605 may be an example of or include the components of device 305, device 405, or a UE 115 as described herein. The device 605 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 610, an I/O controller 615, a transceiver 620, an antenna 625, memory 630, and a processor 640. These components may be in electronic communication via one or more buses (e.g., bus 645) .

The communications manager 610 may establish a connection with a first network, transmit a registration message to a second network for establishing voice over internet protocol services, receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network, determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network, and perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.

The I/O controller 615 may manage input and output signals for the device 605. The I/O controller 615 may also manage peripherals not integrated into the device 605. In some cases, the I/O controller 615 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 615 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 615 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 615 may be implemented as part of a processor. In some cases, a user may interact with the device 605 via the I/O controller 615 or via hardware components controlled by the I/O controller 615.

The transceiver 620 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 620 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 620 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 625. However, in some cases the device may have more than one antenna 625, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 630 may include RAM and ROM. The memory 630 may store computer-readable, computer-executable code 635 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 630 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 640 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 640 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 640. The processor 640 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 630) to cause the device 605 to perform various functions (e.g., functions or tasks supporting timer based network switching to support voice services) .

The code 635 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 635 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 635 may not be directly executable by the processor 640 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 7 shows a flowchart illustrating a method 700 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The operations of method 700 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 700 may be performed by a communications manager as described with reference to FIGs. 3 through 6. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 705, the UE may establish a connection with a first network. The operations of 705 may be performed according to the methods described herein. In some examples, aspects of the operations of 705 may be performed by a connection component as described with reference to FIGs. 3 through 6.

At 710, the UE may transmit a registration message to a second network for establishing voice over internet protocol services. The operations of 710 may be performed according to the methods described herein. In some examples, aspects of the operations of 710 may be performed by a transmission component as described with reference to FIGs. 3 through 6.

At 715, the UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. The operations of 715 may be performed according to the methods described herein. In some examples, aspects of the operations of 715 may be performed by a reception component as described with reference to FIGs. 3 through 6.

At 720, the UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. The operations of 720 may be performed according to the methods described herein. In some examples, aspects of the operations of 720 may be performed by a threshold determination component as described with reference to FIGs. 3 through 6.

At 725, the UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The operations of 725 may be performed according to the methods described herein. In some examples, aspects of the operations of 725 may be performed by a search component as described with reference to FIGs. 3 through 6.

FIG. 8 shows a flowchart illustrating a method 800 that supports timer based network switching to support voice services in accordance with aspects of the present disclosure. The operations of method 800 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 800 may be performed by a communications manager as described with reference to FIGs. 3 through 6. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 805, the UE may establish a connection with a first network. The operations of 805 may be performed according to the methods described herein. In some examples, aspects of the operations of 805 may be performed by a connection component as described with reference to FIGs. 3 through 6.

At 810, the UE may transmit a registration message to a second network for establishing voice over internet protocol services. The operations of 810 may be performed according to the methods described herein. In some examples, aspects of the operations of 810 may be performed by a transmission component as described with reference to FIGs. 3 through 6.

At 815, the UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. The operations of 815 may be performed according to the methods described herein. In some examples, aspects of the operations of 815 may be performed by a reception component as described with reference to FIGs. 3 through 6.

At 820, the UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. The operations of 820 may be performed according to the methods described herein. In some examples, aspects of the operations of 820 may be performed by a threshold determination component as described with reference to FIGs. 3 through 6.

At 825, the UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The operations of 825 may be performed according to the methods described herein. In some examples, aspects of the operations of 825 may be performed by a search component as described with reference to FIGs. 3 through 6.

At 830, the UE may switch the connection from the first network to the third network based at least in part performing the search procedure for the third network. The operations of 830 may be performed according to the methods described herein. In some examples, aspects of the operations of 830 may be performed by a switching component as described with reference to FIGs. 3 through 6.

FIG. 9 shows a flowchart illustrating a method 900 that supports timer based network switching to support voice services 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. 3 through 6. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 905, the UE may establish a connection with a first network. 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 connection component as described with reference to FIGs. 3 through 6.

At 910, the UE may transmit a registration message to a second network for establishing voice over internet protocol services. 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 transmission component as described with reference to FIGs. 3 through 6.

At 915, the UE may receive configuration signaling indicating the time threshold for the UE. 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 reception component as described with reference to FIGs. 3 through 6.

At 920, the UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. The operations of 920 may be performed according to the methods described herein. In some examples, aspects of the operations of 920 may be performed by a reception component as described with reference to FIGs. 3 through 6.

At 925, the UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. The operations of 925 may be performed according to the methods described herein. In some examples, aspects of the operations of 925 may be performed by a threshold determination component as described with reference to FIGs. 3 through 6.

At 930, the UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The operations of 930 may be performed according to the methods described herein. In some examples, aspects of the operations of 930 may be performed by a search component as described with reference to FIGs. 3 through 6.

FIG. 10 shows a flowchart illustrating a method 1000 that supports timer based network switching to support voice services 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. 3 through 6. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1005, the UE may establish a connection with a first network. 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 connection component as described with reference to FIGs. 3 through 6.

At 1010, the UE may transmit a registration message to a second network for establishing voice over internet protocol services. 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 transmission component as described with reference to FIGs. 3 through 6.

At 1015, the UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. 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 a reception component as described with reference to FIGs. 3 through 6.

At 1020, the UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. 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 threshold determination component as described with reference to FIGs. 3 through 6.

At 1025, the UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The operations of 1025 may be performed according to the methods described herein. In some examples, aspects of the operations of 1025 may be performed by a search component as described with reference to FIGs. 3 through 6.

At 1030, the UE may determine, by the UE, the time threshold for the UE. The operations of 1030 may be performed according to the methods described herein. In some examples, aspects of the operations of 1030 may be performed by a threshold determination component as described with reference to FIGs. 3 through 6.

FIG. 11 shows a flowchart illustrating a method 1100 that supports timer based network switching to support voice services 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. 3 through 6. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1105, the UE may establish a connection with a first network. 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 connection component as described with reference to FIGs. 3 through 6.

At 1110, the UE may establish a connection with a fourth network after establishing the connection with the first network and before transmitting the registration message to the second network. 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 connection component as described with reference to FIGs. 3 through 6.

At 1115, the UE may transmit a registration message to a second network for establishing voice over internet protocol services. 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 transmission component as described with reference to FIGs. 3 through 6.

At 1120, the UE may receive a registration failure message from the second network, where the registration failure message indicates a retry timer for retrying a registration procedure with the second network. 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 reception component as described with reference to FIGs. 3 through 6.

At 1125, the UE may determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network. 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 threshold determination component as described with reference to FIGs. 3 through 6.

At 1130, the UE may perform a search procedure for a third network for switching the connection from the first network to the third network based on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported. The operations of 1130 may be performed according to the methods described herein. In some examples, aspects of the operations of 1130 may be performed by a search component as described with reference to FIGs. 3 through 6.

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:

establishing a connection with a first network;

transmitting a registration message to a second network for establishing voice over internet protocol services;

receiving a registration failure message from the second network, wherein the registration failure message indicates a retry timer for retrying a registration procedure with the second network;

determining that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network; and

performing a search procedure for a third network for switching the connection from the first network to the third network based at least in part on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.
The method of claim 1, further comprising:

switching the connection from the first network to the third network based at least in part performing the search procedure for the third network.
The method of claim 2, further comprising:

maintaining the connection with the third network for a duration of the retry timer.
The method of claim 2, further comprising:

establishing a voice connection with the third network based at least in part on switching the connection from the first network to the third network.
The method of claim 2, further comprising:

performing a search procedure for the first network upon expiration of the retry timer for switching the connection from the third network to the first network.
The method of claim 1, further comprising:

receiving configuration signaling indicating the time threshold for the UE.
The method of claim 1, further comprising:

determining, by the UE, the time threshold for the UE.
The method of claim 1, wherein:

the second network comprises an internet protocol multimedia subsystem network; and

the third network comprises a legacy network with respect to the first network.
The method of claim 1, wherein the UE comprises a subscriber identification module that does not support voice over internet protocol services for the first network.
The method of claim 1, further comprising:

establishing a connection with a fourth network after establishing the connection with the first network and before transmitting the registration message to the second network.
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:

establish a connection with a first network;

transmit a registration message to a second network for establishing voice over internet protocol services;

receive a registration failure message from the second network, wherein the registration failure message indicates a retry timer for retrying a registration procedure with the second network;

determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network; and

perform a search procedure for a third network for switching the connection from the first network to the third network based at least in part on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.
The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to:

switch the connection from the first network to the third network based at least in part performing the search procedure for the third network.
The apparatus of claim 12, wherein the instructions are further executable by the processor to cause the apparatus to:

maintain the connection with the third network for a duration of the retry timer.
The apparatus of claim 12, wherein the instructions are further executable by the processor to cause the apparatus to:

establish a voice connection with the third network based at least in part on switching the connection from the first network to the third network.
The apparatus of claim 12, wherein the instructions are further executable by the processor to cause the apparatus to:

perform a search procedure for the first network upon expiration of the retry timer for switching the connection from the third network to the first network.
The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to:

receive configuration signaling indicating the time threshold for the UE.
The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to:

determine, by the UE, the time threshold for the UE.
The apparatus of claim 11, wherein:

the second network comprises an internet protocol multimedia subsystem network; and

the third network comprises a legacy network with respect to the first network.
The apparatus of claim 11, wherein the UE comprises a subscriber identification module that does not support voice over internet protocol services for the first network.
The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to:

establish a connection with a fourth network after establishing the connection with the first network and before transmitting the registration message to the second network.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for establishing a connection with a first network;

means for transmitting a registration message to a second network for establishing voice over internet protocol services;

means for receiving a registration failure message from the second network, wherein the registration failure message indicates a retry timer for retrying a registration procedure with the second network;

means for determining that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network; and

means for performing a search procedure for a third network for switching the connection from the first network to the third network based at least in part on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.
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:

establish a connection with a first network;

transmit a registration message to a second network for establishing voice over internet protocol services;

receive a registration failure message from the second network, wherein the registration failure message indicates a retry timer for retrying a registration procedure with the second network;

determine that the retry timer exceeds a time threshold for the UE and that circuit switched fallback is unsupported by the UE or the first network; and

perform a search procedure for a third network for switching the connection from the first network to the third network based at least in part on determining that the retry timer exceeds the time threshold for the UE and that circuit switched fallback is unsupported.