Techniques for improving wi-fi voice to cellular voice handover

Abstract

Various aspects of the disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) can determine, during an active call on a first radio access technology (RAT), that a first condition for performing a handover from the first RAT to a second RAT is satisfied. The UE can determine that, after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT, and determine that a second condition for performing a handover from the third RAT to the first RAT is satisfied. The UE can refrain from performing the handover from the first RAT to the second RAT based at least in part on the determination that the second RAT will trigger the fallback and the determination that the second condition is satisfied. Numerous other aspects are provided.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority to the following applications: U.S. Provisional Patent Application No. 63 / 198,307, filed October 9, 2020, entitled “TECHNIQUES FOR IMPROVEMENT OF VOICE OVER WI-FI TO VOICE OVER CELLULARHANDOVERS”; and U.S. Non-Provisional Patent Application No. 17 / 450,018, filed October 5, 2021, entitled “TECHNIQUES FOR IMPROVEMENT OF VOICE OVER WI-FI TO VOICE OVER CELLULARHANDOVERS”, which are expressly incorporated herein by reference. Technical Field

[0003] In summary, various aspects of this disclosure relate to wireless communication, and to technologies and apparatus for improving Wi-Fi voice to cellular voice handover. Background Technology

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / Improved LTE is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standard released by the 3rd Generation Partnership Project (3GPP).

[0005] A wireless network may include one or more base stations that support communication for one or more user equipment (UE) devices. The UE may communicate with the base station via downlink and uplink communication. "Downlink" (or "DL") refers to the communication link from the base station to the UE, and "uplink" (or "UL") refers to the communication link from the UE to the base station.

[0006] The above multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different UEs to communicate at the city, country, region, and / or even global levels. New Radio (NR) (which may be referred to as 5G) is an enhancement set to the LTE mobile standard released by 3GPP. NR is designed to better integrate with other open standards by improving spectrum efficiency, reducing costs, improving service, utilizing new spectrum, and using Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) on the downlink (CP-OFDM), and using CP-OFDM and / or Single Carrier Frequency Division Multiplexing (SC-FDM) (also known as Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM)) on the uplink, as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technologies and carrier aggregation, thereby better supporting mobile broadband internet access. As the demand for mobile broadband access continues to grow, further improvements to LTE, NR, and other radio access technologies remain useful. Summary of the Invention

[0007] In some aspects, a method of wireless communication performed by a UE includes: during an active call on a first radio access technology (RAT), determining that a first condition for performing a handover from the first RAT to a second RAT is satisfied; determining that after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and avoiding performing the handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied.

[0008] In some aspects, the determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0009] In some aspects, determining that the second RAT will trigger the fallback includes: determining that the cell identifier associated with the second RAT is included in a stored set of cell identifiers that identifies the cell that triggered the fallback of the second RAT.

[0010] In some aspects, the method includes: determining that the second RAT had triggered a backoff at a time prior to the active call; and storing a cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell for which the second RAT had triggered a backoff.

[0011] In some aspects, the determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0012] In some aspects, the method includes measuring the signal strength associated with the third RAT based at least in part on the determination that the second RAT will trigger the backoff.

[0013] In some aspects, the signal strength associated with the third RAT is measured during the idle time in the second RAT.

[0014] In some aspects, the signal strength associated with the third RAT is measured using the radio frequency (RF) resources of the UE's unused user identity module (SIM).

[0015] In some aspects, the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is an evolved packet system (EPS) fallback.

[0016] In some aspects, a method of wireless communication performed by a UE includes: during an active call on a first RAT, determining that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; determining, at least in part, based on the signal strength of the second RAT, that the active call will move from the second RAT to a third RAT after the handover from the first RAT to the second RAT; and triggering a move from the second RAT to the third RAT, at least in part based on the determination of the signal strength associated with the first RAT within the specific range and the determination that the active call will move from the second RAT to the third RAT.

[0017] In some aspects, triggering the movement includes: when the UE is operating in Radio Resource Control (RRC) idle mode, configuring the priority of the third RAT to be greater than the priority of the second RAT, so that the UE reselects from the second RAT to the third RAT.

[0018] In some aspects, triggering the movement includes: when the UE is operating in RRC connection mode, failure to create a radio link on the second RAT, so that the UE re-establishes the link on the third RAT.

[0019] In some aspects, the method includes: determining that conditions are met for performing a switch from the first RAT to the third RAT; and performing the switch from the first RAT to the third RAT based at least in part on determining that the conditions are met.

[0020] In some aspects, the determination that the active call will be transferred from the second RAT to the third RAT includes: identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT at its location; and determining that the active call will be transferred from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0021] In some respects, the identification of the stored signal strength is based at least in part on the cell identifier associated with the second RAT.

[0022] In some respects, the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0023] In some aspects, a UE for wireless communication includes a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to: during an active call on a first RAT, determine that a first condition for performing a handover from the first RAT to a second RAT is satisfied; determine that after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; determine that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and avoid performing the handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied.

[0024] In some aspects, the determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0025] In some aspects, when it is determined that the second RAT will trigger the fallback, the one or more processors are configured to: determine that the cell identifier associated with the second RAT is included in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell that triggered the fallback of the second RAT.

[0026] In some aspects, the one or more processors are further configured to: determine that the second RAT has triggered a backoff at a time prior to the active call; and store the cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell for which the second RAT has triggered a backoff.

[0027] In some aspects, the determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0028] In some aspects, the one or more processors are also configured to measure the signal strength associated with the third RAT, at least in part, based on the determination that the second RAT will trigger the backoff.

[0029] In some aspects, the signal strength associated with the third RAT is measured during the idle time in the second RAT.

[0030] In some respects, the signal strength associated with the third RAT is measured using the RF resources of the UE's unused SIM.

[0031] In some aspects, the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is EPS fallback.

[0032] In some aspects, a UE for wireless communication includes a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to: during an active call on a first RAT, determine that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; determine, at least in part, based on the signal strength of the second RAT, that the active call will move from the second RAT to a third RAT after the handover from the first RAT to the second RAT; and trigger a move from the second RAT to the third RAT, at least in part based on the determination of the signal strength associated with the first RAT within the specific range and the determination that the active call will move from the second RAT to the third RAT.

[0033] In some aspects, when the movement is triggered, the one or more processors are configured to: when the UE is operating in RRC idle mode, configure the priority of the third RAT to be greater than the priority of the second RAT, so that the UE reselects from the second RAT to the third RAT.

[0034] In some aspects, when the movement is triggered, the one or more processors are configured to: when the UE is operating in RRC connection mode, if the creation of a radio link on the second RAT fails, the UE will re-establish the link on the third RAT.

[0035] In some aspects, the one or more processors are further configured to: determine that conditions are met for performing a switch from the first RAT to the third RAT; and perform the switch from the first RAT to the third RAT based at least in part on the determination that the conditions are met.

[0036] In some aspects, the determination that the active call will be transferred from the second RAT to the third RAT includes: identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT at its location; and determining that the active call will be transferred from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0037] In some respects, the identification of the stored signal strength is based at least in part on the cell identifier associated with the second RAT.

[0038] In some respects, the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0039] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to: during an active call on a first RAT, determine that a first condition for performing a handover from the first RAT to a second RAT is satisfied; determine that after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; determine that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and avoid performing the handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied.

[0040] In some aspects, the determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0041] In some aspects, the UE determines that the second RAT will trigger the fallback by one or more instructions, causing the UE to perform the following operation: determine that the cell identifier associated with the second RAT is included in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell that triggered the fallback of the second RAT.

[0042] In some aspects, the one or more instructions also cause the UE to: determine that the second RAT has triggered a backoff at a time prior to the active call; and store the cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell for which the second RAT has triggered a backoff.

[0043] In some aspects, the determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0044] In some aspects, the one or more instructions also cause the UE to measure the signal strength associated with the third RAT, at least in part based on the determination that the second RAT will trigger the backoff.

[0045] In some aspects, the signal strength associated with the third RAT is measured during the idle time in the second RAT.

[0046] In some respects, the signal strength associated with the third RAT is measured using the RF resources of the UE's unused SIM.

[0047] In some aspects, the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is EPS fallback.

[0048] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to: during an active call on a first RAT, determine that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; determine, at least in part, based on the signal strength of the second RAT, that the active call will be transferred from the second RAT to a third RAT after the handover from the first RAT to the second RAT; and trigger a movement from the second RAT to the third RAT, at least in part based on the determination of the signal strength associated with the first RAT within the specific range and the determination that the active call will be transferred from the second RAT to the third RAT.

[0049] In some aspects, causing the UE to trigger the one or more instructions for the movement causes the UE to perform the following operation: when the UE is operating in RRC idle mode, configure the priority of the third RAT to be greater than the priority of the second RAT, so that the UE reselects from the second RAT to the third RAT.

[0050] In some aspects, the one or more instructions that cause the UE to trigger the movement cause the UE to perform the following operation: when the UE is operating in RRC connection mode, if the creation of a radio link on the second RAT fails, the UE will re-establish the link on the third RAT.

[0051] In some aspects, the one or more instructions also cause the UE to: determine that conditions for performing a handover from the first RAT to the third RAT are met; and perform the handover from the first RAT to the third RAT based at least in part on the determination that the conditions are met.

[0052] In some aspects, the determination that the active call will be transferred from the second RAT to the third RAT includes: identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT at its location; and determining that the active call will be transferred from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0053] In some respects, the identification of the stored signal strength is based at least in part on the cell identifier associated with the second RAT.

[0054] In some respects, the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0055] In some aspects, an apparatus for wireless communication includes: units for determining, during an active call on a first RAT, that a first condition for performing a handover from the first RAT to a second RAT is satisfied; units for determining that, after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; units for determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and units for avoiding performing the handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied.

[0056] In some aspects, the determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0057] In some aspects, the unit for determining that the second RAT will trigger the rollback includes: a unit for determining that a cell identifier associated with the second RAT is included in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell that triggered the rollback of the second RAT.

[0058] In some aspects, the apparatus includes: a unit for determining that the second RAT has triggered a fallback at a time prior to the active call; and a unit for storing a cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cells of the second RAT that have triggered a fallback.

[0059] In some aspects, the determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0060] In some aspects, the apparatus includes a unit for measuring the signal strength associated with the third RAT, based at least in part on the determination that the second RAT will trigger the backoff.

[0061] In some aspects, the signal strength associated with the third RAT is measured during the idle time in the second RAT.

[0062] In some respects, the signal strength associated with the third RAT is measured using the RF resources of the device's unused SIM.

[0063] In some aspects, the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is EPS fallback.

[0064] In some aspects, an apparatus for wireless communication includes: a unit for determining, during an active call on a first RAT, that a signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; a unit for determining, at least in part, based on the signal strength of the second RAT, that the active call will move from the second RAT to a third RAT after the handover from the first RAT to the second RAT; and a unit for triggering a movement from the second RAT to the third RAT, at least in part based on the determination of the signal strength associated with the first RAT within the specific range and the determination that the active call will move from the second RAT to the third RAT.

[0065] In some aspects, the unit for triggering the movement includes a unit for configuring the priority of the third RAT to be greater than the priority of the second RAT when the UE is operating in RRC idle mode, so that the device reselects from the second RAT to the third RAT.

[0066] In some aspects, the unit for triggering the movement includes: a unit for causing the device to re-establish the link on the third RAT when the UE is operating in RRC connection mode and the creation of a radio link on the second RAT fails.

[0067] In some aspects, the apparatus includes: a unit for determining that conditions are met for performing a switch from the first RAT to the third RAT; and a unit for performing the switch from the first RAT to the third RAT based at least in part on the determination that the conditions are met.

[0068] In some aspects, the unit for determining that the active call will be transferred from the second RAT to the third RAT includes: a unit for identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT at its location; and a unit for determining that the active call will be transferred from the second RAT to the third RAT based at least in part on a determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0069] In some respects, the identification of the stored signal strength is based at least in part on the cell identifier associated with the second RAT.

[0070] In some respects, the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0071] In general, the aspects include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication equipment and / or processing systems as fully described herein with reference to the accompanying drawings and description and as shown by the accompanying drawings and description.

[0072] The foregoing has provided a fairly broad overview of the features and technical advantages of examples according to this disclosure in order to better understand the following detailed description. Additional features and advantages will be described below. The disclosed concepts and specific examples can be readily used as the basis for modifying or designing other structures for achieving the same purpose as this disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein (both their organization and manner of operation) and their associated advantages will be better understood when considered in conjunction with the accompanying drawings, based on the following description. Each drawing in the accompanying drawings is provided for illustrative and descriptive purposes and is not intended to define a limitation of the claims. Attached Figure Description

[0073] To gain a full understanding of the foregoing features of this disclosure, a more specific description of the invention, briefly summarized above, can be obtained by referring to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and are therefore not intended to limit the scope of the disclosure, as other equally valid aspects are permissible under this description. The same reference numerals in different drawings may identify the same or similar elements.

[0074] Figure 1 This is a schematic diagram illustrating an example of a wireless network according to this disclosure.

[0075] Figure 2 This is a schematic diagram illustrating an example of communication between a base station and a UE in a wireless network according to this disclosure.

[0076] Figure 3 This is a schematic diagram illustrating an example of an improvement associated with Wi-Fi voice to cellular voice handover according to this disclosure.

[0077] Figure 4A and 4B This is a schematic diagram illustrating another example of an improvement associated with Wi-Fi voice to cellular voice handover according to this disclosure.

[0078] Figure 5 and 6 This is a schematic diagram illustrating an example process associated with improvements to Wi-Fi voice-to-cellular voice handover according to this disclosure.

[0079] Figure 7 and 8 This is a block diagram of an example device for wireless communication based on the present disclosure. Detailed Implementation

[0080] The various aspects of this disclosure are described more fully below with reference to the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art. It will be understood by those skilled in the art that the scope of this disclosure is intended to cover any aspect of this disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of this disclosure. For example, an apparatus or a method may be implemented using any number of the aspects set forth herein. Furthermore, the scope of this disclosure is intended to cover such apparatuses or methods implemented using structures, functions, or structures and functions other than or different from the aspects of this disclosure set forth herein. It should be understood that any aspect of this disclosure disclosed herein may be embodied by one or more elements of the claims.

[0081] Several aspects of a telecommunications system will now be described with reference to various devices and techniques. These devices and techniques will be described in detail below and illustrated in the accompanying drawings, through various frames, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be implemented using hardware, software, or a combination thereof. Whether such an element is implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system.

[0082] While this document may use terms commonly associated with 5G or New Radio (NR) Radio Access Technology (RAT) to describe aspects, aspects of this disclosure may be applied to other RATs, such as 3G RAT, 4G RAT and / or RATs after 5G (e.g., 6G).

[0083] Figure 1This is a schematic diagram illustrating an example of a wireless network 100 according to this disclosure. The wireless network 100 may be or may include elements of a 5G (e.g., NR) network and / or a 4G (e.g., Long Term Evolution (LTE)) network, as well as other examples. The wireless network 100 may include one or more base stations 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d), user equipment (UE) 120 or multiple UEs 120 (shown as UE 120a, UE 120b, UE 120c, UE 120d, and UE 120e), and / or other network entities. Base station 110 is the entity that communicates with UE 120. Base station 110 (sometimes referred to as BS) may include, for example, an NR base station, an LTE base station, a Node B, an eNB (e.g., in 4G), a gNB (e.g., in 5G), an access point, and / or a Transmit / Receive Point (TRP). Each base station 110 may provide communication coverage for a specific geographic area. In the 3rd Generation Partnership Project (3GPP), the term “cell” can refer to the coverage area of ​​base station 110 and / or the base station subsystem serving that coverage area, depending on the context in which the term is used.

[0084] Base station 110 can provide communication coverage for macro cells, pico cells, femtocells, and / or another type of cell. A macro cell can cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access by UE 120 with service subscriptions. A pico cell can cover a relatively small geographic area and can allow unrestricted access by UE 120 with service subscriptions. A femtocell can cover a relatively small geographic area (e.g., a residential area) and can allow restricted access by UE 120 associated with that femtocell (e.g., UE 120 in a Closed User Group (CSG)). Base station 110 for macro cells can be referred to as a macro base station. Base station 110 for pico cells can be referred to as a pico base station. Base station 110 for femtocells can be referred to as a femtocell or a home base station. Figure 1 In the example shown, BS 110a can be a macro base station for macro cell 102a, BS 110b can be a pico base station for pico cell 102b, and BS 110c can be a femto base station for femto cell 102c. A base station can support one or more (e.g., three) cells.

[0085] In some examples, the cell may not be stationary, and the geographical area of ​​the cell may move depending on the location of the mobile base station 110 (e.g., a mobile base station). In some examples, base stations 110 may be interconnected with each other and / or with one or more other base stations 110 or network nodes (not shown) in the wireless network 100 via various types of backhaul interfaces, such as direct physical connections or virtual networks, using any suitable transport network.

[0086] Wireless network 100 may include one or more relay stations. A relay station is an entity that can receive data transmissions from an upstream station (e.g., base station 110 or UE 120) and transmit the data transmissions to a downstream station (e.g., UE 120 or base station 110). A relay station may be a UE 120 capable of relaying transmissions for other UE 120s. Figure 1 In the example shown, BS 110d (e.g., a relay base station) can communicate with BS 110a (e.g., a macro base station) and UE 120d to facilitate communication between BS 110a and UE 120d. The base station 110 for relay communication can be referred to as a relay station, relay base station, repeater, etc.

[0087] Wireless network 100 can be a heterogeneous network comprising different types of base stations 110 (such as macro base stations, pico base stations, femto base stations, relay base stations, etc.). These different types of base stations 110 can have different transmit power levels, different coverage areas, and / or different effects on interference in wireless network 100. For example, macro base stations can have high transmit power levels (e.g., 5 to 40 watts), while pico base stations, femto base stations, and relay base stations can have lower transmit power levels (e.g., 0.1 to 2 watts).

[0088] Network controller 130 can be coupled to or communicate with a group of base stations 110, and can provide coordination and control for these base stations 110. Network controller 130 can communicate with base stations 110 via backhaul communication links. Base stations 110 can communicate with each other directly or indirectly via wireless or wired backhaul communication links.

[0089] UE 120 may be distributed throughout the wireless network 100, and each UE 120 may be stationary or mobile. UE 120 may include, for example, access terminals, terminals, mobile stations, and / or user units. UE 120 may be a cellular phone (e.g., a smartphone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet device, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device, a biometric device, a wearable device (e.g., a smartwatch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring or smart bracelet)), an entertainment device (e.g., a music device, a video device, and / or a satellite radio unit, etc.), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a GPS device, and / or any other suitable device configured to communicate via wireless or wired media.

[0090] Some UEs 120 can be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC UEs and / or eMTC UEs may include, for example, robots, drones, remote devices, sensors, meters, monitors, and / or location tags, which can communicate with a base station, another device (e.g., a remote device), or some other entity. Some UEs 120 can be considered Internet of Things (IoT) devices, and / or may be implemented as NB-IoT (Narrowband IoT) devices. Some UEs 120 can be considered customer premises equipment. UEs 120 may be included within a housing that houses the components of the UE 120, such as processor components and / or memory components. In some examples, the processor components and memory components may be coupled together. For example, the processor components (e.g., one or more processors) and memory components (e.g., memory) may be operatively coupled, communicatively coupled, electronically coupled, and / or electrically coupled.

[0091] Typically, any number of wireless networks 100 can be deployed in a given geographical area. Each wireless network 100 can support a specific RAT and can operate on one or more frequencies. A RAT can be referred to as a radio technology, air interface, etc. A frequency can be referred to as a carrier, channel, etc. Each frequency can support a single RAT in a given geographical area to avoid interference between wireless networks using different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0092] In some examples, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary for communication with each other). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, or vehicle-to-pedestrian (V2P) protocols, and / or mesh networks. In such examples, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described herein as being performed by base station 110.

[0093] Devices in Wireless Network 100 can communicate using the electromagnetic spectrum, which can be subdivided into various categories, bands, channels, etc., by frequency or wavelength. For example, devices in Wireless Network 100 can communicate using one or more operating frequency bands. In 5G NR, two initial operating frequency bands have been identified as frequency range names FR1 (410MHz–7.125GHz) and FR2 (24.25GHz–52.6GHz). It should be understood that although a portion of FR1 is greater than 6GHz, in various documents and articles, FR1 is often (interchangeably) referred to as the “below 6GHz” band. Similar naming issues sometimes arise regarding FR2; although it differs from the extremely high frequency (EHF) band (30GHz–300GHz), it is often (interchangeably) referred to in documents and articles as the “millimeter wave” band, which is identified as such by the International Telecommunication Union (ITU).

[0094] The frequencies between FR1 and FR2 are generally referred to as intermediate frequencies (IFs). Recent 5G NR studies have identified the operating bands of these IFs as the frequency range name FR3 (7.125GHz–24.25GHz). Bands falling within FR3 can inherit FR1 and / or FR2 characteristics, and thus can effectively extend the characteristics of FR1 and / or FR2 to the IF. Furthermore, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6GHz. For example, three higher operating frequency bands have been identified as the frequency range names FR4a or FR4–1 (52.6GHz–71GHz), FR4 (52.6GHz–114.25GHz), and FR5 (114.25GHz–300GHz). Each of these higher frequency bands falls within the EHF band.

[0095] Considering the examples above, unless otherwise specifically stated, it should be understood that when the term "below 6 GHz" is used herein, it can broadly refer to frequencies that are less than 6 GHz, can be within FR1, or can include intermediate frequency band frequencies. Furthermore, unless otherwise specifically stated, it should be understood that when the term "millimeter wave" is used herein, it can broadly refer to frequencies that can include intermediate frequency band frequencies, can be within FR2, FR4, FR4-a or FR4-1 and / or FR5, or can be within the EHF band. It is anticipated that the frequencies included in these operating frequency bands (e.g., FR1, FR2, FR3, FR4, FR4-a, FR4-1 and / or FR5) can be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0096] As pointed out above, Figure 1 This is provided as an example. Other examples may differ from the one provided. Figure 1 The example described.

[0097] Figure 2 This is a schematic diagram illustrating an example of communication between a base station 110 and a UE 120 in a wireless network 100 according to the present disclosure. The base station 110 may be equipped with a set of antennas 234a to 234t, such as T antennas (T≥1). The UE 120 may be equipped with a set of antennas 252a to 252r, such as R antennas (R≥1).

[0098] At base station 110, transmitting processor 220 can receive data from data source 212 intended for UE 120 (or a set of UEs 120). Transmitting processor 220 can select one or more modulation and coding schemes (MCS) for UE 120, at least in part, based on one or more Channel Quality Indicators (CQIs) received from UE 120. Base station 110 can process (e.g., code and modulate) the data for UE 120, and provide data symbols for UE 120, at least in part, based on the MCS selected for UE 120. Transmitting processor 220 can process system information (e.g., semi-static resource partitioning information (SRPI)) and control information (e.g., CQI requests, grants, and / or upper-layer signaling), and provide overhead symbols and control symbols. Transmitting processor 220 can generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS) or demodulation reference signals (DMRS)) and synchronization signals (e.g., primary synchronization signal (PSS) or secondary synchronization signal (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding, if applicable) on data symbols, control symbols, overhead symbols, and / or reference symbols, and can provide a set of output symbol streams (e.g., T output symbol streams) to a set of corresponding modems 232 (e.g., T modems), shown as modems 232a to 232t. For example, each output symbol stream can be provided to a modulator component (shown as MOD) of modem 232. Each modem 232 can use its respective modulator component to process its respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modem 232 can also use its respective modulator component to process (e.g., convert to analog, amplify, filter, and / or upconvert) the output sample stream to obtain a downlink signal. Modems 232a to 232t can transmit a set of downlink signals (e.g., T downlink signals) via a set of corresponding antennas 234 (e.g., T antennas) (shown as antennas 234a to 234t).

[0099] At UE 120, an array of antennas 252 (shown as antennas 252a to 252r) can receive downlink signals from base station 110 and / or other base stations 110, and can provide a set of received signals (e.g., R received signals) to an array of modems 254 (e.g., R modems) (shown as modems 254a to 254r). For example, each received signal can be provided to a demodulator component (shown as a demodulator) of modem 254. Each modem 254 can use its respective demodulator component to condition (e.g., filter, amplify, downconvert, and / or digitize) the received signal to obtain an input sample. Each modem 254 can use the demodulator component to further process the input sample (e.g., for OFDM) to obtain a received symbol. MIMO detector 256 can obtain the received symbol from modulator 254, perform MIMO detection on the received symbol (if applicable), and can provide the detected symbol. The receiver processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE 120 to the data sink 260, and provide decoded control and system information to the controller / processor 280. The term "controller / processor" can refer to one or more controllers, one or more processors, or a combination thereof. The channel processor can determine Reference Signal Received Power (RSRP) parameters, Received Signal Strength Indicator (RSSI) parameters, Reference Signal Received Quality (RSRQ) parameters, and / or CQI parameters, among other examples. In some examples, one or more components of the UE 120 may be included in a housing.

[0100] Network controller 130 may include communication unit 294, controller / processor 290, and memory 292. Network controller 130 may include one or more devices, such as those in a core network. Network controller 130 may communicate with base station 110 via communication unit 294.

[0101] One or more antennas (e.g., antennas 234a to 234t and / or antennas 252a to 252r) may include or may be included within the following: one or more antenna panels, one or more antenna groups, one or more antenna element sets, and / or one or more antenna arrays, and other examples. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include one or more antenna elements (within a single housing or multiple housings), coplanar antenna element sets, non-coplanar antenna element sets, and / or coupled to one or more transmitting and / or receiving components (such as...) Figure 2 One or more antenna elements (one or more components).

[0102] On the uplink, at UE 120, transmit processor 264 can receive and process data from data source 262 and control information from controller / processor 280 (e.g., for reporting including RSRP, RSSI, RSRQ, and / or CQI). Transmit processor 264 can also generate reference symbols for one or more reference signals. Symbols from transmit processor 264 can be pre-coded (if applicable) by TX MIMO processor 266, further processed by modem 254 (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to base station 110. In some examples, modem 254 of UE 120 may include modulator and demodulator. In some examples, UE 120 includes a transceiver. The transceiver may include any combination of antenna 252, modem 254, MIMO detector 256, receive processor 258, transmit processor 264, and / or TX MIMO processor 266. The transceiver may be used by a processor (e.g., controller / processor 280) and memory 282 to perform aspects of any of the methods described herein (e.g., refer to...). Figure 3-8 ).

[0103] At base station 110, uplink signals from UE 120 and other UEs can be received by antenna 234, processed by modem 232 (e.g., demodulator components of modem 232, such as DEMOD), detected by MIMO detector 236 (if applicable), and further processed by receive processor 238 to obtain decoded data and control information transmitted by UE 120. Receive processor 238 can provide decoded data to data sink 239 and decoded control information to controller / processor 240. Base station 110 may include communication unit 244 and can communicate with network controller 130 via communication unit 244. Base station 110 may include scheduler 246 to schedule one or more UEs 120 for downlink and / or uplink communication. In some examples, the modem of base station 110 may include modulator and demodulator. In some examples, base station 110 includes transceiver. The transceiver may include any combination of antenna 234, modem 232, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver may be used by a processor (e.g., controller / processor 240) and memory 242 to perform aspects of any of the methods described herein (e.g., refer to...). Figure 3-8 ).

[0104] The controller / processor 240 of base station 110, the controller / processor 280 of UE 120 and / or Figure 2Any other components may perform one or more techniques associated with improvements to Wi-Fi voice-to-cellular voice handover, as described in more detail elsewhere herein. For example, the controller / processor 240 of base station 110, the controller / processor 280 of UE 120, and / or Figure 2 Any other component can perform or direct, for example Figure 5 Process 500 Figure 6 The operation of process 600 and / or other processes as described herein. Memory 242 and 282 may store data and program code for base station 110 and UE 120, respectively. In some examples, memory 242 and / or memory 282 may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and / or program code) for wireless communication. For example, one or more instructions, when executed by one or more processors of base station 110 and / or UE 120 (e.g., directly, or after compilation, translation, and / or interpretation), may cause one or more processors, UE 120, and / or base station 110 to perform or instruct, for example... Figure 5 Process 500 Figure 6 The operation of process 600 and / or other processes as described herein. In some aspects, execution instructions may include run instructions, translation instructions, compilation instructions, and / or interpretation instructions, as well as other examples.

[0105] In some aspects, UE 120 may include: a unit for determining, during an active call on a first RAT, that a first condition for performing a handover from the first RAT to a second RAT is satisfied; a unit for determining that, after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; a unit for determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; a unit for avoiding performing a handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger a fallback and the determination that the second condition for performing a handover from the third RAT to the first RAT is satisfied; and so on. In some aspects, such a unit may include one or more components of UE 120 described in conjunction with 2, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, etc.

[0106] In some aspects, UE 120 may include: a unit for determining, during an active call on a first RAT, that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; a unit for determining, at least in part, based on the signal strength of the second RAT, that the active call will move from the second RAT to a third RAT after the handover from the first RAT to the second RAT; a unit for triggering a move from the second RAT to the third RAT, at least in part based on the determination that the signal strength associated with the first RAT is within a specific range and the determination that the active call will move from the second RAT to the third RAT; and so on. In some aspects, such a unit may include one or more components of UE 120 described in conjunction with 2, such as controller / processor 280, transmit processor 264, TXMIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, etc.

[0107] Although Figure 2 The boxes in the diagram are shown as different components, but the functions described above with respect to these boxes can be implemented in a single hardware, software, or combined component, or in various combinations of components. For example, the functions described with respect to transmit processor 264, receive processor 258, and / or TX MIMO processor 266 can be performed by or under the control of controller / processor 280.

[0108] As pointed out above, Figure 2 This is provided as an example. Other examples may differ from the one provided. Figure 2 The example described.

[0109] In some wireless communication scenarios, a UE (e.g., UE 120) can be triggered to perform a handover from one RAT to another during an active call (e.g., an active voice call). For example, a UE can be triggered to perform a handover from Wi-Fi to NR during an active call. However, in some cases, handover from one RAT to another during an active call can be problematic.

[0110] For example, a UE in an active call on Wi-Fi can perform a handover from Wi-Fi to NR. However, in some cases, the NR network may not support NR voice, and therefore, the NR network may trigger a UE's move from NR to LTE shortly after the handover from Wi-Fi to NR. Here, if the conditions for triggering a handover from LTE to Wi-Fi are met, the UE will move the call back to Wi-Fi shortly after the UE's move from NR to LTE. This "ping-pong" of the call (e.g., leaving Wi-Fi and returning to Wi-Fi) wastes UE resources (e.g., battery power, processing resources, etc.), wastes network resources, and may degrade call quality in some cases. In such scenarios, it is desirable for the UE to avoid performing the initial handover from Wi-Fi to NR.

[0111] As another example, a UE in an active call over Wi-Fi can perform a handover from Wi-Fi to NR. However, in some cases, the NR network can determine that conditions for triggering a UE's move from NR to LTE are met shortly after the Wi-Fi handover to NR, and therefore, the UE's move from NR to LTE can be triggered shortly after the Wi-Fi handover to NR (e.g., via packet-switched handover (PSHO) or redirection). In such cases, it is desirable for the UE to handover directly from Wi-Fi to LTE (rather than from Wi-Fi to NR and then from NR to LTE) in order to, for example, improve call quality and reduce waste of UE and / or network resources.

[0112] This article describes some of the technologies and devices that enable improvements in Wi-Fi voice to cellular voice switching.

[0113] In some aspects, the UE may determine, during an active call on a first RAT (e.g., Wi-Fi), that a first condition for performing a handover from the first RAT to a second RAT (e.g., NR) is met. Next, the UE may determine that after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT (e.g., LTE), and may determine that a second condition for performing a handover from the third RAT to the first RAT is met. Here, the UE may avoid performing a handover from the first RAT to the second RAT, at least in part, based on the determination that the second RAT will trigger a fallback and the determination that the second condition for performing a handover from the third RAT to the first RAT is met. Additional details regarding such example aspects are provided below.

[0114] In some aspects, the UE can determine, during an active call on a first RAT (e.g., Wi-Fi), that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT (e.g., NR). Next, the UE can determine, at least in part, that the active call will move from the second RAT to a third RAT (e.g., LTE) after the handover from the first RAT to the second RAT, based on the signal strength of the second RAT. Here, the UE can trigger the move from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the first RAT is within a specific range and the determination that the active call will move from the second RAT to the third RAT. Additional details regarding such example aspects are provided below.

[0115] In some respects, these technologies and devices for improving Wi-Fi voice to cellular voice handover reduce waste of UE resources (e.g., battery power, processing resources, etc.), reduce waste of network resources, and / or improve the quality of active calls for the UE.

[0116] Figure 3 This is a schematic diagram illustrating example 300 associated with improvements in Wi-Fi voice to cellular voice handover according to the present disclosure.

[0117] In Example 300, the UE (e.g., UE 120) and a device supporting the first RAT (in Figure 3 The device is identified as RAT1 in the diagram. In some aspects, the first RAT is Wi-Fi, and the device supporting the first RAT can be a Wi-Fi access point. As shown by reference numeral 302, in example 300, the UE is active on the first RAT during a call (e.g., a voice call, a video call, etc.).

[0118] In some aspects, as indicated by reference numeral 304, the UE may determine, during an active call on a first RAT, that a first condition for performing a handover from the first RAT to a second RAT is met. In some aspects, the second RAT is an NR. In some aspects, the UE may determine that the first condition is met based at least in part on a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, and / or the signal strength associated with the second RAT.

[0119] As a specific example, devices that support the second RAT (in) Figure 3The device identified as RAT2 (which may be a base station 110 in the NR network) can transmit a reference signal. Here, as shown by reference numeral 304a, the UE can measure the signal strength associated with the second RAT (e.g., Reference Signal Received Power (RSRP)) at least in part based on the reference signal. As shown by reference numeral 304b, the UE can also measure the signal strength associated with the first RAT (e.g., Received Signal Strength Indicator (RSSI)). Here, the first condition may be that the signal strength associated with the first RAT is less than the signal strength associated with the second RAT. Therefore, if the UE determines that the signal strength associated with the first RAT is less than the signal strength associated with the second RAT (e.g., a threshold is reached), the UE can determine that the first condition is met.

[0120] In some aspects, as indicated by reference numeral 306, the UE can determine that after a switch from a first RAT to a second RAT, the second RAT will trigger a fallback to a third RAT. For example, after an active call switches from the first RAT to the second RAT, the UE can determine that the second RAT will trigger a switch from using the second RAT for cellular connectivity to using the third RAT for cellular connectivity. In some aspects, the third RAT is LTE, and the fallback is an EPS fallback (e.g., enabling an NR UE to switch to the LTE Evolution Packet Core (EPC) for active calls via mobile triggering).

[0121] In some aspects, the UE can determine, at least in part, that a second RAT will trigger a backoff based on a set of cell identifiers stored by the UE, which identifies the cell that triggered the backoff for the second RAT. For example, at a time prior to an active call (e.g., during another active call at an earlier time), the UE may experience a backoff from the second RAT to a third RAT because the cell to which the UE is connected does not support voice calls. When experiencing a backoff associated with a cell of the second RAT, the UE can store the cell identifier of the second RAT cell in a database that stores cell identifiers of second RAT cells that have already triggered backoffs. Therefore, during the current active call, the UE can determine the cell identifier of the second RAT cell to which the UE will connect after switching from the first RAT to the second RAT, and can determine whether the cell identifier is stored in the database. If the cell identifier is stored in the database, the UE can determine that the second RAT will trigger a backoff to the third RAT. It is worth noting that if the cell identifier is not stored in the database (indicating that the second RAT cell may support voice calls), in some aspects, the UE can continue switching from the first RAT to the second RAT. In some respects, the UE may determine in another way that the second RAT will trigger a backoff, for example, based at least in part on the signal strength associated with the second RAT (e.g., alone or in combination with a set of cell identifiers stored by the UE), at least in part on the probability of a backoff determined by the UE, or in some other way.

[0122] As shown by reference numeral 308 in the attached figure, the UE can then determine that a second condition is met for performing a handover from the third RAT to the first RAT. In some aspects, the UE can determine that the second condition is met based at least in part on the signal strength associated with the third RAT.

[0123] As a specific example, devices that support the third RAT (in) Figure 3 The device identified as RAT3 (which may be a base station 110 in an LTE network) can transmit a reference signal. Here, as indicated by reference numeral 308a, the UE can measure the signal strength (e.g., RSRP) associated with the third RAT, at least in part, based on the reference signal. In some aspects, the UE can measure the signal strength associated with the third RAT, at least in part, based on a determination that the second RAT will trigger a backoff. Here, the second condition may be that the signal strength associated with the third RAT is less than a signal strength threshold. Therefore, if the UE determines that the signal strength associated with the third RAT is less than the signal strength threshold, the UE can determine that the second condition is met.

[0124] In some aspects, the UE measures the signal strength associated with the third RAT during the idle time of the second RAT. For example, when the UE includes a single SIM, the UE can measure the signal strength associated with the third RAT during the idle time of the second RAT. Alternatively, in some aspects, the UE uses the RF resources of the UE's unused SIM to measure the signal strength associated with the third RAT. For example, when the UE is a dual-SIM UE (e.g., dual-SIM, dual-active (DSDA) UE, dual-SIM dual-standby (DSDS) UE), the UE can use the RF chain of the unused SIM to measure the signal strength associated with the third RAT.

[0125] As shown by reference numeral 310 in the attached figure, the UE can avoid performing a handover from the first RAT to the second RAT, at least in part, based on the determination that the second RAT will trigger a backoff and the determination that a second condition for performing a handover from the third RAT to the first RAT is met. That is, if the UE (1) determines that the second RAT will trigger a backoff and (2) the second condition for performing a handover from the third RAT to the first RAT is met, the UE can avoid performing a handover from the first RAT to the second RAT. In this way, the UE can prevent "ping-pong" of the call (e.g., leaving the first RAT and returning to the first RAT), thereby saving UE resources (e.g., battery power, processing resources, etc.) and network resources, and improving call quality.

[0126] It is worth noting that if the UE determines that the second condition for performing a handover from the third RAT to the first RAT is not met, in some respects the UE may continue the handover from the first RAT to the second RAT (e.g., even when the UE has determined that the second RAT will trigger a fallback).

[0127] As pointed out above, Figure 3 This is provided as an example. Other examples may differ from the one provided. Figure 3 The example described.

[0128] Figure 4A and 4B This is a schematic diagram illustrating an example 400 associated with an improvement in Wi-Fi voice to cellular voice handover according to the present disclosure.

[0129] In Example 400, the UE (e.g., UE 120) and a device supporting the first RAT (in Figure 4A The UE communicates with a device (identified as RAT1). In some aspects, the first RAT is Wi-Fi, and the device supporting the first RAT can be a Wi-Fi access point. As shown by reference numeral 402, in example 400, the UE is in an active call on the first RAT and has a cellular connection to the second RAT.

[0130] As shown by reference numeral 404, the UE can determine, during an active call on a first RAT, that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT. In some aspects, the second RAT is an NR. In one example, as shown by reference numeral 404a, the UE measures the signal strength (e.g., RSSI) associated with the first RAT. Here, the UE can be configured with a handover threshold that triggers a handover from the first RAT to the second RAT when the signal strength reaches (e.g., is less than or equal to) a specific value. Furthermore, the UE can be configured with information identifying the range above the specific value (e.g., above the handover threshold + X dB, where X > 0). Here, the UE can determine whether the strength associated with the first RAT is within a specific range based at least in part on the result of measuring the signal strength associated with the first RAT.

[0131] As shown by reference numeral 406 in the attached figure, the UE can determine that after a handover from a first RAT to a second RAT, an active call will be transferred from the second RAT to a third RAT. In some aspects, the third RAT is LTE. In some aspects, the UE can determine that after a handover from the first RAT to the second RAT, an active call will be transferred from the second RAT to the third RAT, based at least in part on the signal strength associated with the second RAT. In some aspects, the UE can determine that an active call will be transferred from the second RAT to the third RAT, based at least in part on information indicating the signal strength that previously triggered movement associated with the second RAT.

[0132] As a specific example, a UE's movement from a second RAT to a third RAT can be triggered sometime before the active call (e.g., during another active call at an earlier time). After this movement, the UE can store the cell identifier of the cell to which the UE is connected, and can also store information indicating the signal strength associated with the second RAT at the time the movement was triggered. The UE can store such information in a database that stores the cell identifier of the second RAT cell and the signal strength at the time the movement was triggered from the second RAT cell. Therefore, during the current active call, the UE can determine the cell identifier of the cell of the second RAT that the UE will connect to after the handover from the first RAT to the second RAT, and can measure the signal strength of the cell associated with the second RAT. For example, a device that supports the second RAT (in...) Figure 4AThe device identified as RAT2 (which may be base station 110 in the NR network) can transmit a reference signal, and as shown by reference numeral 406a, the UE can measure the signal strength (e.g., RSRP) associated with the second RAT at least in part based on the reference signal. Next, the UE can determine, at least in part based on information stored by the UE, whether the measured signal strength associated with the cell of the second RAT is equal to or lower than the stored signal strength of the cell of the second RAT at the time of the previous triggering of movement. Here, if the UE determines that the measured signal strength associated with the second RAT is equal to or lower than the stored signal strength, the UE can determine that after the handover from the first RAT to the second RAT, the active call will move from the second RAT to the third RAT. It is worth noting that if the cell identifier is not stored in the database (indicating that the UE has not experienced movement from the cell of the second RAT), in some respects, the UE can continue the handover from the first RAT to the second RAT.

[0133] As shown by reference numeral 408 in the attached figure, the UE may trigger a move from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the first RAT is within a specific range and the determination that an active call will be transferred from the second RAT to the third RAT. That is, if the UE (1) determines that the signal strength associated with the first RAT is within a specific range and (2) the active call will be transferred from the second RAT to the third RAT, the UE may trigger a move from the second RAT to the third RAT. It is worth noting that in some aspects, when the UE triggers a move from the second RAT to the third RAT, the active call does not transfer from the first RAT to the third RAT (i.e., after the UE triggers a move from the second RAT to the third RAT, the active call may remain on the first RAT).

[0134] In some respects, a UE can trigger movement by configuring the priority of the third RAT to be higher than that of the second RAT. For example, when the UE is operating in RRC idle mode, the UE can configure the priority of the third RAT to be higher than that of the second RAT. In some respects, such a configuration results in the UE reselecting from the second RAT to the third RAT.

[0135] In some aspects, a UE can trigger mobility by failing to establish a radio link on a second RAT. For example, when the UE is operating in RRC connected mode, it may fail to establish a radio link on a second RAT. In some aspects, the failure to establish a radio link results in the UE re-establishing the link on a third RAT.

[0136] In this way, the UE can prevent back-to-back handovers (e.g., from Wi-Fi to NR, and then from NR to LTE), thereby saving UE resources (e.g., battery power, processing resources, etc.) and network resources, and improving call quality. It is worth noting that, according to the technique described above, the UE triggers the movement from the second RAT to the third RAT (rather than the network triggering the movement from the second RAT to the third RAT).

[0137] In some aspects, after triggering a move from the second RAT to the third RAT, the UE can perform a handover from the first RAT to the third RAT. For example, as shown by reference numeral 410, and after triggering the move from the second RAT to the third RAT, the UE can determine that conditions for performing a handover from the first RAT to the third RAT are met (e.g., at least in part based on the signal strength of the first RAT reaching a handover threshold). The UE can then perform the handover from the first RAT to the third RAT at least in part based on the determination that the conditions are met.

[0138] Figure 4B This is a graphical illustration of the scene described in association with Example 400. Figure 4B In the example shown, during an active call on the first RAT, the UE is at time t mob The UE determines that the signal strength associated with the first RAT is within a specific range (+X) higher than the handover threshold (RAT1 HO threshold) associated with triggering a handover from the first RAT to the second RAT. Here, the UE determines (e.g., at least in part based on the signal strength of the second RAT and stored information associated with the second RAT, as described above) that after the handover from the first RAT to the second RAT, the active call will be transferred from the second RAT to the third RAT. Therefore, the UE triggers a move from the second RAT to the third RAT.

[0139] As further shown, the UE can trigger a move from the second RAT to the third RAT at time t. ho The handover from the first RAT to the third RAT is performed at time t. That is, the UE can perform the handover after triggering the movement from the second RAT to the third RAT (e.g., after the UE switches from using the second RAT for cellular connectivity to using the third RAT for cellular connectivity). ho The UE performs one or more operations that cause an active call to be switched (e.g., transferred) from a first RAT to a third RAT. For example, the UE may determine that conditions for performing a switch from the first RAT to the third RAT are met (e.g., the signal strength associated with the first RAT is equal to or lower than the RAT1 HO threshold), and may perform the switch accordingly.

[0140] like Figure 4B As shown, at time tmob Previously, the call was made on the first RAT, and the UE used the second RAT for cellular connectivity. Furthermore, at time t... mob With time t ho Between these times, the call occurs on the first RAT, and the UE uses the third RAT for cellular connectivity. Finally, at time t... ho Subsequently, the call takes place on the third RAT, and the UE uses the third RAT for cellular connectivity. It's worth noting that in this scenario, only one handover is performed (from the first RAT to the third RAT).

[0141] As pointed out above, Figure 4A and 4B This is provided as an example. Other examples may differ from the one provided. Figure 4A and 4B The example described.

[0142] Figure 5 This is a schematic diagram illustrating an example process 500 performed by a UE, for example, according to this disclosure. Example process 500 is an example in which a UE (e.g., UE 120) performs operations associated with improvements to Wi-Fi voice to cellular voice handover.

[0143] like Figure 5 As shown, in some aspects, process 500 may include: during an active call on a first RAT, determining that a first condition for performing a handover from the first RAT to a second RAT is met (block 510). For example, the UE (e.g., using...) Figure 7 The determining component 708 described herein can determine, during an active call on the first RAT, that a first condition for performing a handover from the first RAT to the second RAT is met, as described above.

[0144] like Figure 5 Further, in some aspects, process 500 may include: determining that after a handover from a first RAT to a second RAT, the second RAT will trigger a fallback to a third RAT (box 520). For example, the UE (e.g., using...) Figure 7 The determining component 708 described herein can determine that after a switch from the first RAT to the second RAT, the second RAT will trigger a rollback to the third RAT, as described above.

[0145] like Figure 5 As further shown, in some aspects, process 500 may include: determining a second condition (block 530) that satisfies the requirement to perform a handover from a third RAT to a first RAT. For example, the UE (e.g., using...) Figure 7 The determining component 708 described herein can determine whether a second condition is met for performing a switch from the third RAT to the first RAT, as described above.

[0146] like Figure 5 Further, in some aspects, process 500 may include: avoiding a handover from the first RAT to the second RAT (box 540), based at least in part on a determination that the second RAT will trigger a backoff and a determination that a second condition for performing a handover from the third RAT to the first RAT is met. For example, the UE (e.g., using...) Figure 7 The switching component 712 described herein may, at least in part, avoid performing a switch from the first RAT to the second RAT based on the determination that the second RAT will trigger a rollback and the determination that a second condition for performing a switch from the third RAT to the first RAT is met, as described above.

[0147] Process 500 may include additional aspects, such as any single aspect or any combination thereof described below and / or in conjunction with one or more other process descriptions elsewhere described herein.

[0148] In the first aspect, the determination of the first condition for performing a switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference for the second RAT over the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0149] In the second aspect, determining, either alone or in combination with the first aspect, that a second RAT will trigger a fallback includes: determining that a cell identifier associated with the second RAT is included in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell that triggered the fallback of the second RAT.

[0150] In the third aspect, either alone or in combination with one or more of the first and second aspects, process 500 includes: determining that the second RAT has triggered a backoff at a time prior to the active call; and storing the cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell for which the second RAT has triggered a backoff.

[0151] In the fourth aspect, either alone or in combination with one or more of the first to third aspects, the determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0152] In the fifth aspect, either alone or in combination with one or more of the first through fourth aspects, process 500 includes: measuring (e.g., using) at least in part based on the determination that the second RAT will trigger a rollback. Figure 7The signal strength associated with the measurement component 710 (described in the figure) and the third RAT.

[0153] In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the signal strength associated with the third RAT is measured during the idle time period in the second RAT.

[0154] In the seventh aspect, either alone or in combination with one or more of the first to sixth aspects, the signal strength associated with the third RAT is measured using the RF resources of the UE's unused SIM.

[0155] In the eighth aspect, either alone or in combination with one or more aspects from the first to the seventh aspects, the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is EPS fallback.

[0156] Although Figure 5 An example box of process 500 is shown, but in some aspects, process 500 may include... Figure 5 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 500 may be executed in parallel.

[0157] Figure 6 This is a schematic diagram illustrating an example process 600 performed by a UE, for example, in accordance with this disclosure. Example process 600 is an example in which a UE (e.g., UE 120) performs operations associated with improvements to Wi-Fi voice-to-cellular voice handover.

[0158] like Figure 6 As shown, in some aspects, process 600 may include: during an active call on a first RAT, determining that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT (box 610). For example, the UE (e.g., using...) Figure 8 The determining component 808 described herein can determine, during an active call on the first RAT, that the signal strength associated with the first RAT is within a specific range above a handover threshold associated with triggering a handover from the first RAT to the second RAT, as described above.

[0159] like Figure 6 Further, in some aspects, process 600 may include: determining, at least in part, that an active call will be transferred from the second RAT to the third RAT after a handover from the first RAT to the second RAT based on the signal strength of the second RAT (block 620). For example, the UE (e.g., using...) Figure 8The determining component 808 described herein can determine, at least in part, that an active call will be transferred from the second RAT to the third RAT after a switch from the first RAT to the second RAT, as described above, based on the signal strength of the second RAT.

[0160] like Figure 6 Further, in some aspects, process 600 may include: triggering a move from the second RAT to the third RAT based at least in part on a determination that the signal strength associated with the first RAT is within a specific range and a determination that an active call will be transferred from the second RAT to the third RAT (box 630). For example, the UE (e.g., using...) Figure 8 The movement triggering component 810 described herein can trigger movement from the second RAT to the third RAT, at least in part, based on the determination that the signal strength associated with the first RAT is within a certain range and the determination that an active call will be transferred from the second RAT to the third RAT, as described above.

[0161] like Figure 6 As further shown, in some aspects, process 600 may optionally include: after triggering a move from the second RAT to the third RAT, performing a handover of the active call from the first RAT to the third RAT (block 640). For example, the UE (e.g., using...) Figure 8 The switching component 812 described herein can perform an active call to switch from the first RAT to the third RAT after triggering a move from the second RAT to the third RAT, as described above.

[0162] Process 600 may include additional aspects, such as any single aspect or any combination thereof described below and / or in conjunction with one or more other process descriptions elsewhere described herein.

[0163] In the first aspect, triggering a move includes: when the UE is operating in RRC idle mode, configuring the priority of the third RAT to be greater than the priority of the second RAT, so that the UE reselects from the second RAT to the third RAT.

[0164] In the second aspect, either alone or in combination with the first aspect, triggering a move includes: when the UE is operating in RRC connection mode, failure to establish a radio link on a second RAT, so that the UE re-establishes the link on a third RAT.

[0165] In the third aspect, either alone or in combination with one or more of the first and second aspects, process 600 includes: determining that conditions are met for performing a switch from the first RAT to the third RAT; and performing (e.g., using switching component 812) the switch from the first RAT to the third RAT based at least in part on the determination that the conditions are met.

[0166] In the fourth aspect, either alone or in combination with one or more of the first to third aspects, the determination that an active call will be transferred from the second RAT to the third RAT includes: identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT; and determining that the active call will be transferred from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0167] In the fifth aspect, the identification of the stored signal strength, either alone or in combination with one or more of the first to fourth aspects, is based at least in part on the cell identifier associated with the second RAT.

[0168] In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0169] Although Figure 6 An example box of process 600 is shown, but in some aspects, process 600 may include... Figure 6 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 600 may be executed in parallel.

[0170] Figure 7 This is a block diagram of an example device 700 for wireless communication. Device 700 may be a UE, or a UE may include device 700. In some aspects, device 700 includes a receiving component 702 and a transmitting component 704, which can communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, device 700 can use the receiving component 702 and the transmitting component 704 to communicate with another device 706 (such as a UE, a base station, or another wireless communication device). As further shown, device 700 may include one or more of a determining component 708, a measuring component 710, or a switching component 712, and other examples.

[0171] In some respects, device 700 can be configured to perform the functions described herein. Figure 3 One or more operations described herein. Alternatively or concurrently, the apparatus 700 may be configured to perform one or more processes described herein, such as... Figure 5 The process is 500. In some aspects, Figure 7 The device 700 and / or one or more components shown may include the elements described above. Figure 2 One or more components of the UE as described. Alternatively, Figure 7One or more components shown can be combined with the above. Figure 2 The description refers to implementation within one or more components. Alternatively, one or more components in the set of components may be implemented, at least partially, as software stored in memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or processor to perform the function or operation of the component.

[0172] Receiver 702 may receive communications from device 706, such as reference signals, control information, data communications, or combinations thereof. Receiver 702 may provide the received communications to one or more other components of device 700. In some aspects, receiver 702 may perform signal processing on the received communications (e.g., filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, demapping, equalization, interference cancellation, or decoding, and other examples), and may provide the processed signal to one or more other components of device 706. In some aspects, receiver 702 may include the elements described above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receiver processors, controllers / processors, memory, or combinations thereof.

[0173] Transmitting component 704 can transmit communications, such as reference signals, control information, data communications, or combinations thereof, to device 706. In some aspects, one or more other components of device 706 can generate communications and provide the generated communications to transmitting component 704 for transmission to device 706. In some aspects, transmitting component 704 can perform signal processing on the generated communications (e.g., filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, and other examples), and can transmit the processed signal to device 706. In some aspects, transmitting component 704 can include the combinations described above. Figure 2 The described UE includes one or more antennas, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof. In some aspects, the transmit component 704 may be co-located with the receive component 702 in a transceiver.

[0174] The determining component 708 can determine, during an active call on the first RAT, that a first condition for performing a handover from the first RAT to the second RAT is met. In some aspects, the determining component 708 may include the conditions described above. Figure 2The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof. Determining component 708 can determine that, following a handover from a first RAT to a second RAT, the second RAT will trigger a backoff to a third RAT. Determining component 708 can determine that a second condition for performing a handover from the third RAT to the first RAT is met. Handover component 712 can avoid performing a handover from the first RAT to the second RAT, at least in part, based on the determination that the second RAT will trigger a backoff and the determination that the second condition for performing a handover from the third RAT to the first RAT is met. In some aspects, handover component 712 may include the combination of the above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof.

[0175] Component 708 can determine that the second RAT triggered a fallback at a time prior to the active call.

[0176] The determining component 708 may store the cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cells of the second RAT that have triggered fallback.

[0177] Measurement component 710 can measure the signal strength associated with the third RAT based at least in part on the determination that the second RAT will trigger a backoff. In some aspects, measurement component 710 may include the combination of the above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof.

[0178] Figure 7 The number and arrangement of components shown are provided as an example. In reality, they can exist in combination with... Figure 7 The components shown are compared to additional components, fewer components, different components, or components arranged in a different way. Furthermore, Figure 7 The two or more components shown can be implemented within a single component, or Figure 7 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 7 The set (one or more) components shown can perform actions described by Figure 7 The other set of components shown performs one or more functions.

[0179] Figure 8This is a block diagram of an example device 800 for wireless communication. Device 800 may be a UE, or a UE may include device 800. In some aspects, device 800 includes a receiving component 802 and a transmitting component 804, which can communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, device 800 can use the receiving component 802 and the transmitting component 804 to communicate with another device 806 (such as a UE, a base station, or another wireless communication device). As further shown, device 800 may include one or more of a determining component 808, a movement triggering component 810, or a handover component 812, and other examples.

[0180] In some respects, device 800 can be configured to perform the functions described herein. Figure 4A and 4B One or more operations described herein. Alternatively or concurrently, the apparatus 800 may be configured to perform one or more processes described herein, such as... Figure 6 The process is 600. In some aspects, Figure 8 The device 800 and / or one or more components shown may include the elements described above. Figure 2 One or more components of the UE as described. Alternatively, Figure 8 One or more components shown can be combined with the above. Figure 2 The description refers to implementation within one or more components. Alternatively, one or more components in the set of components may be implemented, at least partially, as software stored in memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or processor to perform the function or operation of the component.

[0181] Receiver 802 may receive communications from device 806, such as reference signals, control information, data communications, or combinations thereof. Receiver 802 may provide the received communications to one or more other components of device 800. In some aspects, receiver 802 may perform signal processing on the received communications (e.g., filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, demapping, equalization, interference cancellation, or decoding, and other examples), and may provide the processed signal to one or more other components of device 806. In some aspects, receiver 802 may include the elements described above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receiver processors, controllers / processors, memory, or combinations thereof.

[0182] Transmitting component 804 can transmit communications, such as reference signals, control information, data communications, or combinations thereof, to device 806. In some aspects, one or more other components of device 806 can generate communications and provide the generated communications to transmitting component 804 for transmission to device 806. In some aspects, transmitting component 806 can perform signal processing (e.g., filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, and other examples) on the generated communications and can transmit the processed signal to device 806. In some aspects, transmitting component 804 can include the combinations described above. Figure 2 The described UE includes one or more antennas, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof. In some aspects, the transmit component 804 may be co-located with the receive component 802 in a transceiver.

[0183] Determining component 808 can determine, during an active call on a first RAT, that the signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT. In some aspects, determining component 808 may include the above-described combination of... Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof. Determining component 808 may determine, at least in part, that an active call will transfer from the second RAT to the third RAT after a handover from the first RAT to the second RAT, based on the signal strength of the second RAT. Mobility triggering component 810 may trigger a move from the second RAT to the third RAT, at least in part, based on a determination that the signal strength associated with the first RAT is within a specific range and a determination that an active call will transfer from the second RAT to the third RAT. In some aspects, mobility triggering component 810 may include the combination of the above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof.

[0184] Component 808 can determine whether the conditions for performing a switch from the first RAT to the third RAT are met.

[0185] The switching component 812 can perform the switching from the first RAT to the third RAT, at least in part, based on determining that certain conditions are met. In some aspects, the switching component 812 may include the elements described above. Figure 2The described UE includes one or more antennas, demodulators, MIMO detectors, receive processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof.

[0186] Figure 8 The number and arrangement of components shown are provided as an example. In reality, they can exist in combination with... Figure 8 The components shown are compared to additional components, fewer components, different components, or components arranged in a different way. Furthermore, Figure 8 The two or more components shown can be implemented within a single component, or Figure 8 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 8 The set (one or more) components shown can perform actions described by Figure 8 The other set of components shown performs one or more functions.

[0187] The following provides a summary of some aspects of this disclosure:

[0188] Aspect 1: A method for wireless communication performed by a UE, comprising: during an active call on a first RAT, determining that a first condition for performing a handover from the first RAT to a second RAT is satisfied; determining that after the handover from the first RAT to the second RAT, the second RAT will trigger a fallback to a third RAT; determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and avoiding performing the handover from the first RAT to the second RAT, at least in part based on the determination that the second RAT will trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied.

[0189] Aspect 2: According to the method of aspect 1, wherein the determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: a preference indicating that the second RAT is superior to the first RAT for a voice call, the signal strength associated with the first RAT, or the signal strength associated with the second RAT.

[0190] Aspect 3: The method according to any one of Aspects 1-2, wherein determining that the second RAT will trigger the fallback comprises: determining that the cell identifier associated with the second RAT is included in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell that triggered the fallback of the second RAT.

[0191] Aspect 4: The method according to any one of Aspects 1-3 further includes: determining that the second RAT has triggered a backoff at a time prior to the active call; and storing a cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cell for which the second RAT has triggered a backoff.

[0192] Aspect 5: The method according to any one of Aspects 1-4, wherein the determination of the second condition for performing the switching from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

[0193] Aspect 6: The method according to any one of Aspects 1-5 further includes: measuring the signal strength associated with the third RAT based at least in part on the determination that the second RAT will trigger the backoff.

[0194] Aspect 7: According to the method of aspect 6, wherein the signal strength associated with the third RAT is measured during the idle time in the second RAT.

[0195] Aspect 8: The method according to any one of Aspects 6-7, wherein the signal strength associated with the third RAT is measured using the RF resources of the unused SIM of the UE.

[0196] Aspect 9: The method according to any one of Aspects 1-8, wherein the first RAT is Wi-Fi, the second RAT is NR, the third RAT is LTE, and the fallback is EPS fallback.

[0197] Aspect 10: A method of wireless communication performed by a UE, comprising: during an active call on a first RAT, determining that a signal strength associated with the first RAT is within a specific range higher than a handover threshold associated with triggering a handover from the first RAT to a second RAT; determining, at least in part, based on the signal strength of the second RAT, that the active call will move from the second RAT to a third RAT after the handover from the first RAT to the second RAT; and triggering a move from the second RAT to the third RAT, at least in part based on the determination of the signal strength associated with the first RAT within the specific range and the determination that the active call will move from the second RAT to the third RAT.

[0198] Aspect 11: According to the method of aspect 10, triggering the movement includes: when the UE is operating in RRC idle mode, configuring the priority of the third RAT to be greater than the priority of the second RAT, so that the UE reselects from the second RAT to the third RAT.

[0199] Aspect 12: The method according to any one of Aspects 10-11, wherein triggering the movement comprises: when the UE is operating in RRC connection mode, failure to create a radio link on the second RAT, so that the UE re-establishes the link on the third RAT.

[0200] Aspect 13: The method according to any one of aspects 10-12 further includes: determining that conditions for performing a switch from the first RAT to the third RAT are met; and performing the switch from the first RAT to the third RAT based at least in part on determining that the conditions are met.

[0201] Aspect 14: The method according to any one of Aspects 10-13, wherein the determination that the active call will be transferred from the second RAT to the third RAT comprises: identifying the signal strength of a stored signal that previously triggered a move associated with the second RAT at its location; and determining that the active call will be transferred from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the second RAT is less than or equal to the signal strength of the stored signal.

[0202] Aspect 15: The method according to aspect 14, wherein the identification of the stored signal strength is based at least in part on a cell identifier associated with the second RAT.

[0203] Aspect 16: The method according to any one of Aspects 10-15, wherein the first RAT is Wi-Fi, the second RAT is NR, and the third RAT is LTE.

[0204] Aspect 17: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to one or more of aspects 1-9.

[0205] Aspect 18: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the one or more processors being configured to perform the method according to one or more of aspects 1-9.

[0206] Aspect 19: An apparatus for wireless communication, comprising at least one unit for performing the method according to one or more of aspects 1-9.

[0207] Aspect 20: A non-transitory computer-readable medium storing code for wireless communication, said code including instructions executable by a processor to perform the methods described in one or more of aspects 1-9.

[0208] Aspect 21: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform the method according to one or more aspects of aspects 1-9.

[0209] Aspect 22: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to one or more of aspects 10-16.

[0210] Aspect 23: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the one or more processors being configured to perform the method according to one or more aspects of aspects 10-16.

[0211] Aspect 24: An apparatus for wireless communication, comprising at least one unit for performing the method according to one or more of aspects 10-16.

[0212] Aspect 25: A non-transitory computer-readable medium storing code for wireless communication, said code including instructions executable by a processor to perform the methods described in one or more of aspects 10-16.

[0213] Aspect 26: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform the method according to one or more aspects of aspects 10-16.

[0214] The foregoing disclosure provides explanations and descriptions, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made based on the foregoing disclosure, or modifications and variations may be derived from practice in the aspects.

[0215] As used herein, the term "component" is intended to be interpreted broadly as hardware and / or a combination of hardware and software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other names, "software" should be interpreted broadly as meaning instructions, instruction sets, code, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures and / or functions, and other examples. As used herein, processors are implemented using hardware and / or a combination of hardware and software. It will be apparent to those skilled in the art that the systems and / or methods described herein can be implemented using various forms of hardware and / or combinations of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not intended to limit any aspect. Therefore, the operation and behavior of systems and / or methods are described herein without reference to specific software code, as those skilled in the art will understand that software and hardware can be designed to implement systems and / or methods at least in part based on the descriptions herein.

[0216] As used in this article, depending on the context, “meeting the threshold” can refer to a value greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc.

[0217] Even if a specific combination of features is recited in the claims and / or disclosed in the specification, such combinations are not intended to limit the disclosure of the aspects. Many features can be combined in a manner not specifically recited in the claims and / or disclosed in the specification. The disclosure of an aspect includes a combination of each dependent claim with each other claim in the claim set. As used herein, the phrase “at least one of” referring to the list of items refers to any combination of those items, including individual members. For example, “at least one of a, b, or c” is intended to cover a, b, c, a+b, a+c, b+c, and a+b+c, as well as any combination of multiples of the same element (e.g., a+a, a+a+a, a+a+b, a+a+c, a+b+b, a+c+c, b+b, b+b+b, b+b+c, c+c, and c+c+c or any other ordering of a, b, and c).

[0218] None of the elements, actions, or instructions used herein should be construed as critical or essential unless explicitly stated otherwise. Furthermore, as used herein, the articles “a” and “one” are intended to include one or more items and are interchangeable with “one or more.” Furthermore, as used herein, the article “described” is intended to include one or more items referenced in conjunction with the article “described” and is interchangeable with “one or more.” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items and are interchangeable with “one or more.” Where only one item is anticipated, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “has,” “have,” “having,” etc., are intended to be open-ended terms that do not limit the elements they modify (e.g., an element “has” A may also have B). Furthermore, unless explicitly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.” Furthermore, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and / or” unless otherwise expressly stated (e.g., if used in conjunction with “any” or “only one of”).

Claims

1. A method for wireless communication performed by a user equipment (UE), comprising: During an active call on a first radio access technology (RAT), a first condition for performing a handover from the first RAT to a second RAT is determined to be met; It is determined that after the switch from the first RAT to the second RAT, the second RAT will trigger a rollback to the third RAT; Determine if a second condition is met for performing a switch from the third RAT to the first RAT; as well as The switch from the first RAT to the second RAT is avoided, at least in part, based on the determination that the second RAT will trigger the rollback and the determination that the second condition for performing the switch from the third RAT to the first RAT is met.

2. The method according to claim 1, wherein, The determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: This indicates a preference for the second RAT over the first RAT for voice calls. The signal strength associated with the first RAT, or The signal strength associated with the second RAT.

3. The method according to claim 1, wherein, Determining that the second RAT will trigger the fallback includes: The cell identifier associated with the second RAT is determined to be included in a stored set of cell identifiers, which identifies the cell that triggered the fallback of the second RAT.

4. The method according to claim 1, further comprising: It was determined that the second RAT had triggered a fallback at a time prior to the active call; as well as The cell identifier associated with the second RAT is stored in a stored set of cell identifiers, which identifies the cells of the second RAT that have triggered fallback.

5. The method according to claim 1, wherein, The determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

6. The method according to claim 1, further comprising: The signal strength associated with the third RAT is measured based at least in part on the determination that the second RAT will trigger the backoff.

7. The method according to claim 6, wherein, The signal strength associated with the third RAT is measured during the idle time in the second RAT.

8. The method according to claim 6, wherein, The signal strength associated with the third RAT is measured using the radio frequency (RF) resources of the UE's unused user identity module (SIM).

9. The method according to claim 1, wherein, The first RAT is Wi-Fi, the second RAT is New Radio (NR), the third RAT is Long Term Evolution (LTE), and the fallback is Evolved Packet System (EPS) fallback.

10. A user equipment (UE) for wireless communication, comprising: One or more memory units; as well as One or more processors coupled to the one or more memories, wherein the one or more memories and the one or more processors are configured to: During an active call on a first radio access technology (RAT), a first condition for performing a handover from the first RAT to a second RAT is determined to be met; It is determined that after the switch from the first RAT to the second RAT, the second RAT will trigger a rollback to the third RAT; Determine if a second condition is met for performing a switch from the third RAT to the first RAT; as well as The switch from the first RAT to the second RAT is avoided, at least in part, based on the determination that the second RAT will trigger the rollback and the determination that the second condition for performing the switch from the third RAT to the first RAT is met.

11. The UE according to claim 10, wherein, The determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: This indicates a preference for the second RAT over the first RAT for voice calls. The signal strength associated with the first RAT, or The signal strength associated with the second RAT.

12. The UE according to claim 10, wherein, When it is determined that the second RAT will trigger the rollback, the one or more processors are configured to: The cell identifier associated with the second RAT is determined to be included in a stored set of cell identifiers, which identifies the cell that triggered the fallback of the second RAT.

13. The UE according to claim 10, wherein, The one or more processors are further configured to: It was determined that the second RAT had triggered a fallback at a time prior to the active call; and The cell identifier associated with the second RAT is stored in a stored set of cell identifiers, which identifies the cells of the second RAT that have triggered fallback.

14. The UE according to claim 10, wherein, The determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

15. The UE according to claim 10, wherein, The one or more processors are further configured to: The signal strength associated with the third RAT is measured based at least in part on the determination that the second RAT will trigger the backoff.

16. The UE according to claim 15, wherein, The signal strength associated with the third RAT is measured during the idle time in the second RAT.

17. The UE according to claim 15, wherein, The signal strength associated with the third RAT is measured using the radio frequency (RF) resources of the UE's unused user identity module (SIM).

18. A non-transitory computer-readable medium storing an instruction set, the instruction set comprising: One or more instructions, which, when executed by one or more processors of a user equipment (UE), cause the UE to: During an active call on a first radio access technology (RAT), a first condition for performing a handover from the first RAT to a second RAT is determined to be met; It is determined that after the switch from the first RAT to the second RAT, the second RAT will trigger a rollback to the third RAT; Determine if a second condition is met for performing a switch from the third RAT to the first RAT; as well as The switch from the first RAT to the second RAT is avoided, at least in part, based on the determination that the second RAT will trigger the rollback and the determination that the second condition for performing the switch from the third RAT to the first RAT is met.

19. The non-transitory computer-readable medium according to claim 18, wherein, The determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: This indicates a preference for the second RAT over the first RAT for voice calls. The signal strength associated with the first RAT, or The signal strength associated with the second RAT.

20. The non-transitory computer-readable medium according to claim 18, wherein, This causes the UE to determine that the second RAT will trigger the one or more instructions for the fallback, and also causes the UE to: The cell identifier associated with the second RAT is determined to be included in a stored set of cell identifiers, which identifies the cell that triggered the fallback of the second RAT.

21. The non-transitory computer-readable medium according to claim 18, wherein, The one or more instructions also cause the UE to: It was determined that the second RAT had triggered a fallback at a time prior to the active call; as well as The cell identifier associated with the second RAT is stored in a stored set of cell identifiers, which identifies the cells of the second RAT that have triggered fallback.

22. The non-transitory computer-readable medium according to claim 18, wherein, The determination of the second condition for performing the switch from the third RAT to the first RAT is based at least in part on the signal strength associated with the third RAT.

23. The non-transitory computer-readable medium according to claim 18, wherein, The one or more instructions also cause the UE to: The signal strength associated with the third RAT is measured based at least in part on the determination that the second RAT will trigger the backoff.

24. The non-transitory computer-readable medium according to claim 23, wherein, The signal strength associated with the third RAT is measured during the idle time in the second RAT.

25. The non-transitory computer-readable medium according to claim 23, wherein, The signal strength associated with the third RAT is measured using the radio frequency (RF) resources of the UE's unused user identity module (SIM).

26. The non-transitory computer-readable medium according to claim 18, wherein, The first RAT is Wi-Fi, the second RAT is New Radio (NR), the third RAT is Long Term Evolution (LTE), and the fallback is Evolved Packet System (EPS) fallback.

27. A wireless communication device, comprising: A unit for determining, during an active call on a first radio access technology (RAT), a first condition for performing a handover from the first RAT to a second RAT; A unit for determining that, after the switch from the first RAT to the second RAT, the second RAT will trigger a rollback to the third RAT; A unit for determining a second condition that is met for performing a switch from the third RAT to the first RAT; as well as A unit for avoiding the switching from the first RAT to the second RAT based at least in part on a determination that the second RAT will trigger the rollback and a determination that the second condition for performing the switching from the third RAT to the first RAT is met.

28. The apparatus according to claim 27, wherein, The determination of the first condition for performing the switch from the first RAT to the second RAT is based at least in part on at least one of the following: This indicates a preference for the second RAT over the first RAT for voice calls. The signal strength associated with the first RAT, or The signal strength associated with the second RAT.

29. The apparatus according to claim 27, wherein, The unit for determining that the second RAT will trigger the rollback includes: The cell identifier associated with the second RAT is included in a stored set of cell identifiers, which identifies the cell that triggered the fallback of the second RAT.

30. The apparatus of claim 27, further comprising: Units used to determine that the second RAT has triggered a fallback at a time prior to the active call; as well as This is used to store the cell identifier associated with the second RAT in a stored set of cell identifiers, the stored set of cell identifiers identifying the cells of the second RAT that have triggered a fallback.

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