# US 2021/0345185 A1 · Fast return to 5g new radio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0345185 A1 - Document ID: US20210345185A1 - Status: Published application - Kind: A1 - Application number: 16/863,522 - Filed: 2020-04-30 - Published: 2021-11-04 - Earliest claimed: 2020-04-30 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Sree Ram Kodali; Farouk Belghoul; Shashikant Tiwari; Sridhar Prakasam; Vijay Venkataraman - Web page: https://patentgrep.com/patent/US20210345185A1 ## CPC - H04W 36/0072: {of resource information of target access point} - H04W 36/0085: {Hand-off measurements} - H04W 48/18: Selecting a network or a communication service - H04W 76/38: triggered by timers - H04W 36/0022: {for transferring data sessions between adjacent core network technologies} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Re-connecting to a first radio access network (RAN) of a first radio access technology (RAT) may include initially connecting to the first RAN. A connection associated with a voice call may then be connected that includes connecting to a RAN of a second RAT. In response to the voice call connecting to the second RAN, information for both a frequency and a cell associated with connecting to the first RAN may be stored. An end to the voice call may be identified. In response to determining that the voice call has ended, a timer may be generated at the UE that comprises a specified time period and the timer and the information stored for both the frequency and the cell associated with connecting to the first RAN may be utilized to re-connect to the first RAN. ## Claims ### Claim 1 An apparatus of a user equipment (UE), comprising: one or more processors configured to: connect to a first radio access network (RAN) of a first radio access technology (RAT); create a connection associated with a voice call, wherein creating the connection associated with the voice call includes performing a handover procedure or a redirection procedure to a second RAN of a second RAT; in response to the voice call connecting to the second RAN, store information for both a frequency and a cell associated with connecting to the first RAN; identify that the voice call has ended; and in response to determining that the voice call has ended: generate a timer at the UE comprising a specified time period; and utilize the timer and the information stored for both the frequency and the cell associated with connecting to the first RAN to re-connect to the first RAN; and a memory configured to store the information for both the frequency and the cell associated with connecting to the first RAN. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the one or more processors are further configured to: determine that a radio resource control (RRC) connection release associated with the second RAN with re-direction to thereby re-connect to the first RAN occurred before the specified time period of the generated timer expired or that handover to thereby connect to the first RAN occurred before the specified time period of the generated timer expired; and at least partially in response to determining that re-connection to the first RAN has occurred, stop the generated timer. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the one or more processors are further configured to: determine that connection to the second RAN has been terminated and that the generated timer has not yet expired; and in response to determining that connection to the second RAN has been terminated and that the generated timer has not yet expired: stop the generated timer; and force immediate re-selection associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein immediate re-selection associated with the first RAN comprises using the information stored for both the frequency and the cell associated with connecting to the first RAN without measuring candidate cells or comparing measurements to re-selection thresholds. ### Claim 5 (depends on 3) The apparatus of claim 3, wherein the one or more processors are further configured to: determine that the immediate re-selection was not successful; and in response to determining that the immediate re-selection was not successful, perform cell selection on one or more cells of the first RAN that are different than the cell associated with connecting to the first RAN. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the one or more processors are further configured to: determine that performing cell selection on the one or more cells of the first RAN was unsuccessful; and in response to determining that performing cell selection was unsuccessful, re-connect to the second RAN. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the instructions further configure the one or more processors to: determine that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated; and in response to determining that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated: stop the generated timer; abort the connection with the second RAN; and perform re-direction associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein re-direction associated with the first RAN comprises using the information stored for both the frequency and the cell associated with connecting to the first RAN without measuring candidate cells or comparing measurements to re-selection thresholds. ### Claim 9 (depends on 7) The apparatus of claim 7, wherein the one or more processors are further configured to: determine that the performed re-direction associated with the first RAN was unsuccessful; and in response to determining that the performed re-direction was unsuccessful, perform cell selection on one or more cells of the first RAN that are different than the cell associated with connecting to the first RAN. ### Claim 10 (depends on 7) The apparatus of claim 7, wherein the one or more processors are further configured to: determine that performing cell selection on the one or more cells of the first RAN was unsuccessful; and in response to determining that performing cell selection was unsuccessful, re-connect to the second RAN. ### Claim 11 (depends on 7) The apparatus of claim 7, wherein the specified time period of the generated timer is 100 milliseconds. ### Claim 12 A computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a processor of a user equipment (UE) configured to re-connect to a first radio access network (RAN) of a first radio access technology (RAT), cause the processor to: connect to the first RAN; create a connection associated with a voice call, wherein creating the connection associated with the voice call includes performing a handover procedure or a redirection procedure to a second RAN of a second RAT; in response to the voice call connecting to the second RAN, store information for both a frequency and a cell associated with connecting to the first RAN; identify that the voice call has ended; and in response to determining that the voice call has ended: generate a timer at the UE comprising a specified time period; and utilize the timer and the information stored for both the frequency and the cell associated with connecting to the first RAN to re-connect to the first RAN. ### Claim 13 (depends on 12) The computer-readable storage medium of claim 12, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the instructions further configure the processor to: determine that a radio resource control (RRC) connection release associated with the second RAN with re-direction to thereby re-connect to the first RAN occurred before the specified time period of the generated timer expired or that handover to thereby connect to the first RAN occurred before the specified time period of the generated timer expired; and at least partially in response to determining that re-connection to the first RAN has occurred, stop the generated timer. ### Claim 14 (depends on 12) The computer-readable storage medium of claim 12, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the instructions further configure the processor to: determine that connection to the second RAN has been terminated and that the generated timer has not yet expired; and in response to determining that connection to the second RAN has been terminated and that the generated timer has not yet expired: stop the generated timer; and force immediate re-selection associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN. ### Claim 15 (depends on 14) The computer-readable storage medium of claim 14, wherein immediate re-selection associated with the first RAN comprises using the information stored for both the frequency and the cell associated with connecting to the first RAN without measuring candidate cells or comparing measurements to re-selection thresholds. ### Claim 16 (depends on 14) The computer-readable storage medium of claim 14, wherein the instructions further configure the processor to: determine that the immediate re-selection was not successful; and in response to determining that the immediate re-selection was not successful, perform cell selection on one or more cells of the first RAN that are different than the cell associated with connecting to the first RAN. ### Claim 17 (depends on 16) The computer-readable storage medium of claim 16, wherein the instructions further configure the processor to: determine that performing cell selection on the one or more cells of the first RAN was unsuccessful; and in response to determining that performing cell selection was unsuccessful, re-connect to the second RAN. ### Claim 18 (depends on 12) The computer-readable storage medium of claim 12, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein the instructions further configure the processor to: determine that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated; and in response to determining that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated: stop the generated timer; abort the connection with the second RAN; and perform re-direction associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN. ### Claim 19 (depends on 18) The computer-readable storage medium of claim 18, wherein re-direction associated with the first RAN comprises using the information stored for both the frequency and the cell associated with connecting to the first RAN without measuring candidate cells or comparing measurements to re-selection thresholds. ### Claim 20 (depends on 18) The computer-readable storage medium of claim 18, wherein the instructions further configure the processor to: determine that the performed re-direction associated with the first RAN was unsuccessful; and in response to determining that the performed re-direction was unsuccessful, perform cell selection on one or more cells of the first RAN that are different than the cell associated with connecting to the first RAN. ### Claim 21 (depends on 18) The computer-readable storage medium of claim 18, wherein the instructions further configure the processor to: determine that performing cell selection on the one or more cells of the first RAN was unsuccessful; and in response to determining that performing cell selection was unsuccessful, re-connect to the second RAN. ### Claim 22 (depends on 18) The computer-readable storage medium of claim 18, wherein the specified time period of the generated timer is 500 milliseconds. ### Claim 23 A method of a user equipment (UE) re-connecting to a first radio access network (RAN) of a first radio access technology (RAT), the method comprising: connecting to the first RAN; creating a connection associated with a voice call, wherein creating the connection associated with the voice call includes performing a handover procedure or a redirection procedure to a second RAN of a second RAT; in response to the voice call connecting to the second RAN, storing information for both a frequency and a cell associated with connecting to the first RAN; identifying that the voice call has ended; and in response to determining that the voice call has ended: generating a timer at the UE comprising a specified time period; and utilizing the timer and the information stored for both the frequency and the cell associated with connecting to the first RAN to re-connect to the first RAN. ### Claim 24 (depends on 23) The method of claim 23, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein utilizing the timer and the information stored for both the stored frequency and the cell further comprises: determining that a radio resource control (RRC) connection release associated with the second RAN with re-direction to thereby re-connect to the first RAN occurred before the specified time period of the generated timer expired or that handover to thereby connect to the first RAN occurred before the specified time period of the generated timer expired; and at least partially in response to determining that re-connection to the first RAN has occurred, stopping the generated timer. ### Claim 25 (depends on 23) The method of claim 23, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein utilizing the timer and the information stored for both the stored frequency and the cell further comprises: determining that connection to the second RAN has been terminated and that the generated timer has not yet expired; and in response to determining that connection to the second RAN has been terminated and that the generated timer has not yet expired: stopping the generated timer; and forcing immediate re-selection associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN. ### Claim 26 (depends on 23) The method of claim 23, wherein the first RAT comprises a new radio (NR) RAT and the second RAT comprises a long term evolution (LTE) RAT, and wherein utilizing the timer and the information stored for both the stored frequency and the cell further comprises: determining that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated; and in response to determining that the specified time of the generated timer has expired and that connection to the second RAN has not been terminated: stopping the generated timer; aborting the connection with the second RAN; and performing re-direction associated with the first RAN based on the information stored for both the frequency and the cell associated with connecting to the first RAN.