# US 12,004,019 B2 · Techniques for improvement of voice over Wi-Fi to voice over cellular handovers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,019 B2 - Document ID: US12004019B2 - Status: Granted - Kind: B2 - Application number: 17/450,018 - Filed: 2021-10-05 - Published: 2022-04-14 - Granted: 2024-06-04 - Earliest claimed: 2020-10-09 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Vikram Singh; Yong Xie; Carlos Marcelo Dias Pazos - Web page: https://patentgrep.com/patent/US12004019B2 ## CPC - H04W 36/0022: {for transferring data sessions between adjacent core network technologies} - H04W 48/18: Selecting a network or a communication service - H04W 36/00224: {between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]} - H04W 36/1446: {wherein at least one of the networks is unlicensed} - H04W 36/30: by measured or perceived connection quality data - H04W 36/008375: {based on historical data} - H04W 84/12: WLAN [Wireless Local Area Networks] - H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may 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 may determine that the second RAT would trigger a fallback to a third RAT after the handover from the first RAT to the second RAT and that a second condition for performing a handover from the third RAT to the first RAT is satisfied. The UE may 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 would trigger the fallback and the determination that the second condition is satisfied. Numerous other aspects are provided. ## Claims ### Claim 1 A method of wireless communication performed by a user equipment (UE), comprising: determining, 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; determining that the second RAT would trigger a fallback to a third RAT after the handover from the first RAT to the second RAT; determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and refraining from performing the handover from the first RAT to the second RAT based at least in part on the determination that the second RAT would trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied. ### Claim 2 (depends on 1) The method of claim 1, wherein the determination that the first condition for performing the handover from the first RAT to the second RAT is satisfied is based at least in part on at least one of: a preference indicating that the second RAT is preferred over the first RAT for voice calls, a signal strength associated with the first RAT, or a signal strength associated with the second RAT. ### Claim 3 (depends on 1) The method of claim 1, wherein determining that the second RAT would trigger the fallback comprises: determining that a cell identifier associated with the second RAT is included in a set of stored cell identifiers that identifies cells of the second RAT that trigger fallbacks. ### Claim 4 (depends on 1) The method of claim 1, further comprising: determining that the second RAT has triggered a fallback at a time prior to the active call, and storing a cell identifier associated with the second RAT in a set of stored cell identifiers that identifies cells of the second RAT that have triggered fallbacks. ### Claim 5 (depends on 1) The method of claim 1, wherein the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied is based at least in part on a signal strength associated with the third RAT. ### Claim 6 (depends on 1) The method of claim 1, further comprising: measuring a signal strength associated with the third RAT based at least in part on the determination that the second RAT would trigger the fallback. ### Claim 7 (depends on 6) The method of claim 6, wherein the signal strength associated with the third RAT is measured during an idle time in the second RAT. ### Claim 8 (depends on 6) The method of claim 6, wherein the signal strength associated with the third RAT is measured using a radio frequency (RF) resource of an unused subscriber identification module (SIM) of the UE. ### Claim 9 (depends on 1) The method of 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 an Evolved Packet System (EPS) fallback. ### Claim 10 A user equipment (UE) for wireless communication, comprising: one or more memories; and one or more processors coupled to the one or more memories, the one or more memories and the one or more processors configured to: 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; determine that the second RAT would trigger a fallback to a third RAT after the handover from the first RAT to the second RAT; determine that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and 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 would trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied. ### Claim 11 (depends on 10) The UE of claim 10, wherein the determination that the first condition for performing the handover from the first RAT to the second RAT is satisfied is based at least in part on at least one of: a preference indicating that the second RAT is preferred over the first RAT for voice calls, a signal strength associated with the first RAT, or a signal strength associated with the second RAT. ### Claim 12 (depends on 10) The UE of claim 10, wherein the one or more processors, when determining that the second RAT would trigger the fallback, are configured to: determine that a cell identifier associated with the second RAT is included in a set of stored cell identifiers that identifies cells of the second RAT that trigger fallbacks. ### Claim 13 (depends on 10) The UE of claim 10, wherein the one or more processors are further configured to: determine that the second RAT has triggered a fallback at a time prior to the active call, and store a cell identifier associated with the second RAT in a set of stored cell identifiers that identifies cells of the second RAT that have triggered fallbacks. ### Claim 14 (depends on 10) The UE of claim 10, wherein the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied is based at least in part on a signal strength associated with the third RAT. ### Claim 15 (depends on 10) The UE of claim 10, wherein the one or more processors are further configured to: measure a signal strength associated with the third RAT based at least in part on the determination that the second RAT would trigger the fallback. ### Claim 16 (depends on 15) The UE of claim 15, wherein the signal strength associated with the third RAT is measured during an idle time in the second RAT. ### Claim 17 (depends on 15) The UE of claim 15, wherein the signal strength associated with the third RAT is measured using a radio frequency (RF) resource of an unused subscriber identification module (SIM) of the UE. ### Claim 18 A non-transitory computer-readable medium storing a set of instructions, the set of instructions comprising: one or more instructions that, when executed by one or more processors of a user equipment (UE), cause the UE to: 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; determine that the second RAT would trigger a fallback to a third RAT after the handover from the first RAT to the second RAT; determine that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and 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 would trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied. ### Claim 19 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the determination that the first condition for performing the handover from the first RAT to the second RAT is satisfied is based at least in part on at least one of: a preference indicating that the second RAT is preferred over the first RAT for voice calls, a signal strength associated with the first RAT, or a signal strength associated with the second RAT. ### Claim 20 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the one or more instructions that cause the UE to determine that the second RAT would trigger the fallback further cause the UE to: determine that a cell identifier associated with the second RAT is included in a set of stored cell identifiers that identifies cells of the second RAT that trigger fallbacks. ### Claim 21 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the one or more instructions further cause the UE to: determine that the second RAT has triggered a fallback at a time prior to the active call, and store a cell identifier associated with the second RAT in a set of stored cell identifiers that identifies cells of the second RAT that have triggered fallbacks. ### Claim 22 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied is based at least in part on a signal strength associated with the third RAT. ### Claim 23 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the one or more instructions further cause the UE to: measure a signal strength associated with the third RAT based at least in part on the determination that the second RAT would trigger the fallback. ### Claim 24 (depends on 23) The non-transitory computer-readable medium of claim 23, wherein the signal strength associated with the third RAT is measured during an idle time in the second RAT. ### Claim 25 (depends on 23) The non-transitory computer-readable medium of claim 23, wherein the signal strength associated with the third RAT is measured using a radio frequency (RF) resource of an unused subscriber identification module (SIM) of the UE. ### Claim 26 (depends on 18) The non-transitory computer-readable medium of 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 an Evolved Packet System (EPS) fallback. ### Claim 27 An apparatus, comprising: means for determining, 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; means for determining that the second RAT would trigger a fallback to a third RAT after the handover from the first RAT to the second RAT; means for determining that a second condition for performing a handover from the third RAT to the first RAT is satisfied; and means for refraining from performing the handover from the first RAT to the second RAT based at least in part on the determination that the second RAT would trigger the fallback and the determination that the second condition for performing the handover from the third RAT to the first RAT is satisfied. ### Claim 28 (depends on 27) The apparatus of claim 27, wherein the determination that the first condition for performing the handover from the first RAT to the second RAT is satisfied is based at least in part on at least one of: a preference indicating that the second RAT is preferred over the first RAT for voice calls, a signal strength associated with the first RAT, or a signal strength associated with the second RAT. ### Claim 29 (depends on 27) The apparatus of claim 27, wherein the means for determining that the second RAT would trigger the fallback comprise: means for determining that a cell identifier associated with the second RAT is included in a set of stored cell identifiers that identifies cells of the second RAT that trigger fallbacks. ### Claim 30 (depends on 27) The apparatus of claim 27, further comprising: means for determining that the second RAT has triggered a fallback at a time prior to the active call, and means for storing a cell identifier associated with the second RAT in a set of stored cell identifiers that identifies cells of the second RAT that have triggered fallbacks.