Cell Re-Selection in a Device Configured to Operate According to Multiple Cellular Communication Protocols

• US 20130344872A1
• Filed: 10/25/2012
• Published: 12/26/2013
• Est. Priority Date: 06/26/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Su, Li, Nukala, Gaurav
• Granted Patent: US 9,055,495 B2
• Time in Patent Office: Days
• US Class Current: 455/437
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 52/0238 where the received signal is an unwanted signal, e.g. interference or idle signal
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Cell re-selection in a device configured to operate according to multiple cellular communication protocols. The device may operate according to a first cellular communication protocol at a first time, which may include attaching to a first cell. The device may operate according to a second cellular communication protocol at a second time. Operations according to the first cellular communication protocol may be suspended while operating according to the second cellular communication protocol. The device may attempt to resume operating according to the first cellular communication protocol at a third time. This may include measuring one or more of signal strength or signal quality of the first cell. The wireless device may select a cell to which to attach at the third time based at least in part on the measured signal strength and signal quality of the first cell.

Claims

1. A method for cell re-selection, wherein the method is implemented by a wireless device implementing a plurality of cellular communication protocols, the method comprising:

operating according to a first cellular communication protocol at a first time, comprising attaching to a first cell that operates according to the first cellular communication protocol;

operating according to a second cellular communication protocol at a second time, comprising attaching to a second cell that operates according to the second cellular communication protocol, wherein operations according to the first cellular communication protocol are suspended while operating according to the second cellular communication protocol;

attempting to resume operating according to the first cellular communication protocol at a third time, comprising;

measuring a signal strength metric of the first cell;

measuring a signal quality metric of the first cell;

selecting a cell to which to attach based at least in part on the measured signal strength and signal quality metrics of the first cell.

2. The method of claim 1, wherein selecting a cell to which to attach comprises:

determining that signal strength of the first cell is greater than a signal strength threshold;

determining that signal quality of the first cell is less than a signal quality threshold;

performing a cell re-selection procedure based on determining that signal strength of the first cell is greater than the signal strength threshold and determining that signal quality of the first cell is less than the signal quality threshold.

3. The method of claim 2, wherein performing the cell re-selection procedure comprises searching for nearby cells that operate according to the first cellular communication protocol.

4. The method of claim 1, wherein selecting a cell to which to attach comprises:

determining that signal strength of the first cell is less than a signal strength threshold;

determining that signal quality of the first cell is less than a signal quality threshold;

performing a cell re-selection procedure based on determining that signal strength of the first cell is less than the signal strength threshold and determining that signal quality of the first cell is less than the signal quality threshold.

5. The method of claim 4, wherein performing the cell re-selection procedure comprises searching for nearby cells that operate according to the first cellular communication protocol and searching for nearby cells that operate according to one or more cellular communication protocols other than the first cellular communication protocol.

6. The method of claim 5, further comprising:

measuring signal strength and/or signal quality of the second cell;

comparing the signal strength and/or signal quality of the second cell to the signal strength and/or signal quality of the first cell;

comparing the signal strength and/or signal quality of the second cell to one or more signal strength and/or signal quality thresholds;

selecting the second cell to which to attach based on the comparisons;

attaching to the second cell via an inter-radio-access-technology (IRAT) connection at the third time.

7. The method of claim 1,

wherein the selected cell operates according to the first cellular communication protocol, wherein the method further comprises:

resuming operating according to the first cellular communication protocol in conjunction with the selected cell at the third time, wherein resuming operating according to the first cellular communication protocol comprises resuming operations which were initiated at the first time and suspended at the second time.

8. The method of claim 1,

wherein the wireless device is implements the first and second cellular communication protocols using a shared radio, wherein the first cellular communication protocol comprises a first protocol stack, wherein the second cellular communication protocol comprises a second protocol stack, wherein only one of the first and second protocol stacks controls the shared radio at a time.

9. The method of claim 1,

wherein the first cellular communication protocol is LTE, wherein the second cellular communication protocol is 1xRTT.

10. A wireless user equipment (UE) device configured to communicate using a plurality of radio access technologies (RATs) using a single radio, wherein the UE comprises:

a radio, wherein the radio comprises circuitry configured for wireless communication, wherein the radio is configured for use according to either of a first radio access technology or a second radio access technology;

logic configured to control the radio, wherein the logic is configured to;

initiate operations according to the first radio access technology, wherein initiating operations according to the first radio access technology comprises attaching to a first cell which operates according to the first radio access technology;

initiate operations according to the second radio access technology, wherein operations according to the first radio access technology are suspended during the operations according to the second radio access technology;

resume operations according to the first radio access technology, wherein to resume operations according to the first radio access technology, the logic is configured to;

measure a signal strength metric of the first cell;

measure a signal quality metric of the first cell;

select a cell to which to attach based at least in part on the measured signal strength and signal quality metrics of the first cell.

11. The UE of claim 10, wherein to select a cell to which to attach, the logic is configured to:

compare the measured signal strength and signal quality metrics of the first cell to one or more thresholds; and

determine whether or not to perform a cell re-selection procedure based on said comparing.

12. The UE of claim 11,

wherein the cell re-selection procedure comprises searching for cells that operate according to the first radio access technology and selecting a cell to which to attach based at least in part on one or more signal strength metrics or one or more signal quality metrics.

13. The UE of claim 12,

wherein the cell re-selection procedure further comprises searching for cells that operate according to one or more radio access technologies other than the first radio access technology.

14. The UE of claim 11,

wherein the logic is configured to determine to perform the cell re-selection procedure if comparing the measured signal strength and signal quality metrics of the first cell to the one or more thresholds indicates that there is a high probability that there is a nearby cell having a greater signal strength than the first cell.

15. The UE of claim 11,

wherein the logic is configured to attempt to re-attach to the first cell if comparing the measured signal strength and signal quality metrics of the first cell to the one or more thresholds indicates that the first cell provides acceptable signal strength and/or signal quality.

16. The UE of claim 10,

wherein selecting a cell to which to attach comprises:

if signal strength of the first cell is greater than a first signal strength threshold and signal quality of the first cell is less than a first signal quality threshold, performing a first cell re-selection procedure;

if signal strength of the first cell is less than a second signal strength threshold and signal quality of the first cell is less than a second signal quality threshold, performing a second cell re-selection procedure.

17. The UE of claim 16,

wherein the first cell re-selection procedure comprises searching for nearby cells that operate according to the first radio access technology;

wherein the second cell re-selection procedure comprises searching for nearby cells that operate according to the first radio access technology and searching for nearby cells that operate according to at least one other radio access technology.

18. A non-transitory computer accessible memory medium comprising program instructions executable by a wireless device for re-selecting a cell, wherein the wireless device comprises a radio configured to operate according to either of a first cellular communication protocol or a second cellular communication protocol, wherein the program instructions are executable to:

operate according to the first cellular communication protocol at a first time, comprising communicating with a first cell that operates according to the first cellular communication protocol;

operate according to the second cellular communication protocol at a second time, comprising communicating with a second cell that operates according to the second cellular communication protocol, wherein operations according to the first cellular communication protocol are suspended while operating according to the second cellular communication protocol;

attempt to resume operating according to the first cellular communication protocol at a third time, wherein to attempt to resume operating according to the first cellular communication protocol at the third time, the program instructions are executable to;

measure a signal strength metric of the first cell;

measure a signal quality metric of the first cell;

compare signal strength and signal quality of the first cell with one or more thresholds;

select a cell with which to communicate based at least in part on comparing the signal strength and signal quality of the first cell with the one or more thresholds.

19. The memory medium of claim 18, wherein the program instructions are further executable to:

if comparing signal strength and signal quality of the first cell with one or more thresholds produces a first result, perform a first cell re-selection procedure, wherein the first result is a result indicating that there is a high probability that a nearby cell with a stronger signal strength than the first cell is available;

if comparing signal strength and signal quality of the first cell with one or more thresholds produces a second result, select the first cell to which to re-attach without performing the first cell re-selection procedure, wherein the second result is a result indicating that the first cell will likely provide adequate service.

20. The memory medium of claim 19, wherein the program instructions are further executable to:

if comparing signal strength and signal quality of the first cell with one or more thresholds produces a third result, perform a second cell re-selection procedure, wherein the third result is a result indicating that the first cell may not provide adequate service.

21. The memory medium of claim 20,

wherein the first cell re-selection procedure comprises measuring signal strength and/or signal quality of nearby cells that operate according to the first cellular communication protocol;

wherein the second cell re-selection procedure comprises measuring signal strength and/or signal quality both of nearby cells that operate according to the first cellular communication protocol and of nearby cells that operate according to one or more cellular communication protocols other than the first cellular communication protocol.

22. A user equipment (UE) device, comprising:

a radio, comprising one or more antennas for performing wireless communication;

a processor;

a computer accessible memory medium comprising program instructions for resuming communicating according to a first wireless communication protocol after an interruption to communicating according to the first wireless communication protocol, wherein prior to the interruption the UE communicated with a first cell according to the first wireless communication protocol, wherein the program instructions are executable by the processor to, after the interruption;

measure a signal strength metric of the first cell;

measure a signal quality metric of the first cell;

select a cell to which to attach based at least in part on the measured signal strength and signal quality metrics of the first cell.

23. The UE device of claim 22,

wherein the UE device is configured to communicate according to either of the first wireless communication protocol or a second wireless communication protocol using the radio;

wherein the interruption comprises the UE device using the radio to communicate according to the second wireless communication protocol for a period of time.

24. The UE of claim 22, wherein the program instructions are further executable to:

compare the measured signal strength and signal quality metrics of the first cell to one or more thresholds;

wherein if comparing the measured signal strength and signal quality metrics of the first cell to the one or more thresholds yields a first result, selecting the cell to which to attach comprises selecting the first cell without performing a cell re-selection procedure;

wherein if comparing the measured signal strength and signal quality metrics of the first cell to the one or more thresholds yields a second result, selecting the cell to which attach comprises performing a cell re-selection procedure.

25. The UE of claim 22, wherein prior to the interruption the UE was performing one or procedures according to the first wireless communication protocol, wherein the program instructions are further executable to:

suspend the one or more procedures according to the first wireless communication protocol during the interruption;

resume the suspended one or more procedures after selecting the cell to which to attach.