NETWORK CELL TRANSITIONS FOR VOLTE DEVICES AT CALL INITIATION

• US 20140126544A1
• Filed: 10/29/2013
• Published: 05/08/2014
• Est. Priority Date: 11/02/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Khay-Ibbat, Samy, Tabet, Tarik
• Granted Patent: US 10,009,819 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 28/0221 power availability or consumption
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 40/08 based on transmission power
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service

Abstract

Apparatus and methods of performing a network cell transition for a voice over long term evolution (VoLTE) capable mobile device. Initially, the mobile device can detect a call initiation event. Thereafter, the mobile device determines whether a radio signal power associated with its serving LTE network base station is less than a radio access technology (RAT) specific threshold (i.e., an LTE-specific threshold). In a scenario where the radio signal power is less than the RAT-specific threshold the mobile device can effectuate a transition to an available neighbor network base station employing a legacy RAT, prior to establishing a voice call. When the mobile device is in a radio resource control (RRC) connected mode the network cell transition may be associated with an induced network handover procedure. Alternatively, when the mobile device is in an RRC idle mode the network cell transition may be associated with network reselection procedure.

Claims

1. A method of causing a network cell transition for a mobile device at call initiation, the method comprising:

detecting a call initiation event at the mobile device;

in response to detecting the call initiation event, evaluating a radio signal power associated with a serving network base station to determine whether the mobile device is to transition from the serving network base station to a neighbor network base station prior to establishing a voice call associated with the call initiation event;

transitioning the mobile device from the serving network base station to the neighbor network base station when the radio signal power associated with the serving network base station is less than a radio access technology (RAT) specific threshold; and

establishing the voice call at the mobile device via the neighbor network base station after the network cell transition.

2. The method of claim 1, wherein the serving network base station employs a long term evolution (LTE) RAT and the neighbor network base station employs a legacy RAT that is different than the LTE RAT of the serving network base station.

3. The method of claim 2, wherein the mobile device is a multi-mode communication device that is capable of voice over LTE (VoLTE) communications with the serving network base station employing the LTE RAT.

4. The method of claim 1, wherein the transitioning of the mobile device from the serving network base station to the neighbor network base station occurs via a network handover procedure when the mobile device is in a long term evolution (LTE) radio resource control (RRC) connected mode.

5. The method of claim 4, wherein network handover procedure comprises:

generating an exaggerated measurement report at the mobile device comprising a modified radio signal power value associated with the serving network base station or a modified radio signal power value associated with the neighbor network base station; and

transmitting the exaggerated measurement report to the serving network base station to trigger a handover of the mobile device from the serving network base station to the neighbor network base station prior to establishing the voice call.

6. The method of claim 1, wherein the transitioning of the mobile device from the serving network base station to the neighbor network base station occurs via a network reselection procedure when the mobile device is in a long term evolution (LTE) radio resource control (RRC) idle mode.

7. The method of claim 6, wherein the network reselection procedure comprises the mobile device autonomously performing a network reselection to the neighbor network base station prior to establishing the voice call.

8. The method of claim 1, wherein the RAT-specific threshold is a network cell transition threshold that is stored at the mobile device, and

wherein the RAT-specific threshold is different than a network handover threshold that is RAT-generic.

9. A method of initiating a network cell transition at a mobile device prior to establishing a voice call, the method comprising:

measuring a reference signal received power (RSRP) of a first network base station;

comparing the measured RSRP of the first network base station to a radio access technology (RAT) specific threshold;

transitioning the mobile device from the first network base station to a second network base station when the measured RSRP of the first network base station is less than the RAT-specific threshold; and

establishing the voice call at the mobile device via the second network base station after the network cell transition.

10. The method of claim 9, wherein the mobile device is a multi-mode communication device that is capable of voice over LTE (VoLTE) communications with the first network base station and circuit-switched voice communications with the second network base station.

11. The method of claim 9, wherein the transitioning of the mobile device from the first network base station to the second network base station occurs via a network handover procedure when the mobile device is in a long term evolution (LTE) radio resource control (RRC) connected mode.

12. The method of claim 11, wherein network handover procedure comprises:

generating an exaggerated measurement report at the mobile device comprising a modified RSRP associated with the first network base station or a modified RSRP associated with the second network base station; and

transmitting the exaggerated measurement report to the first network base station to trigger a handover of the mobile device from the first network base station to the second network base station prior to establishing the voice call.

13. The method of claim 9, wherein the transitioning of the mobile device from the first network base station to the second network base station occurs via a network reselection procedure when the mobile device is in a long term evolution (LTE) radio resource control (RRC) idle mode.

14. The method of claim 13, wherein the network reselection procedure comprises the mobile device autonomously performing a network reselection to the second network base station prior to establishing the voice call.

15. A wireless communication device comprising:

a radio frequency (RF) circuit;

one or more processors coupled to the RF circuit; and

a memory coupled to the one or more processors,

wherein the one or more processors are configured to execute computer-executable instructions stored within the memory to cause the wireless communication device to;

measure a reference signal received power (RSRP) of a serving network base station;

compare the measured RSRP of the serving network base station to a radio access technology (RAT) specific threshold;

transition from the serving network base station to a neighbor network base station when the RSRP of the serving network base station is less than the RAT-specific threshold; and

establish a voice call via the neighbor network base station after the transition.

16. The wireless communication device of claim 15, wherein the wireless communication device is a multi-mode communication device that is capable of voice over LTE (VoLTE) communications with the serving network base station and circuit-switched voice communications with the neighbor network base station.

17. The wireless communication device of claim 15, wherein the transition from the serving network base station to the neighbor network base station occurs via a network handover procedure when the wireless communication device is in a long term evolution (LTE) radio resource control (RRC) connected mode.

18. The wireless communication device of claim 17, wherein as part of the network handover procedure the one or more processors are configured to execute computer-executable instructions stored within the memory to further cause the wireless communication device to:

generate an exaggerated measurement report including a modified RSRP associated with the serving network base station or a modified RSRP associated with the neighbor network base station; and

transmit the exaggerated measurement report to the serving network base station to trigger a handover from the serving network base station to the neighbor network base station prior to establishing the voice call.

19. The wireless communication device of claim 15, wherein the transition from the serving network base station to the neighbor network base station occurs via a network reselection procedure when the wireless communication device is in a long term evolution (LTE) radio resource control (RRC) idle mode.

20. The wireless communication device of claim 19, wherein as part of the network reselection procedure the one or more processors are configured to execute computer-executable instructions stored within the memory to further cause the wireless communication device to autonomously perform a network reselection to the neighbor network base station prior to establishing the voice call.