Radio link monitoring and cell search techniques for high movement speeds

Patent metadata

Field	Value
Publication number	US-10820248-B2
Application number	US-201716605335-A
Country	US
Kind code	B2
Filing date	May 4, 2017
Priority date	May 4, 2017
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

This disclosure relates to techniques for performing radio link monitoring and cell searching when moving at high speeds. A movement speed of a wireless device may be determined. When performing a cell search, the manner of the cell search may depend on the movement speed of the wireless device, potentially including cells that are associated with high movement speed being more highly prioritized when the wireless device is determined to be at a higher movement speed than when the wireless device is determined to be at a lower movement speed.

First claim

The invention claimed is:

1. An apparatus, comprising:
a processor configured to cause a wireless device to:
detect a movement speed of the wireless device; and
perform a cell search, wherein the cell search comprises scanning a plurality of frequencies for cells within communication range of the wireless device, wherein an order in which the frequencies are scanned is determined based at least in part on the determined movement speed of the wireless device, wherein a subset of the plurality of frequencies are scanned earlier in the order during the cell search when the wireless device is determined to be at a higher movement speed than when the wireless device is determined to be at a lower movement speed.

2. The apparatus of claim 1 , wherein to detect the movement speed of the wireless device, the processor is further configured to cause the wireless device to:
detect, camp on or attach to a serving cell; and
determine that the serving cell is associated with high movement speed based at least in part on an indication broadcast by the serving cell.

3. The apparatus of claim 2 , wherein the processor is further configured to cause the wireless device to, at a later time:
determine that the wireless device has not re-selected to, handed over to, or detected a serving cell associated with high movement speed for at least a predetermined period of time; and
perform a second cell search, wherein the subset of the plurality of frequencies are scanned later in the order during the second cell search based at least in part on determining that the wireless device has not re-selected to, handed over to, or detected a serving cell associated with high movement speed for at least the predetermined period of time.

4. The apparatus of claim 1 , wherein said detecting the movement speed comprises determining the wireless device is moving at a high speed based on one or more of:
an amount of doppler shift detected in cellular communication signals received by the wireless device;
a velocity calculation based on information from a global positioning system (GPS) module of the wireless device;
one or more measurements performed by motion sensing circuitry of the wireless device; or
a number of cell re-selections and/or handovers that have occurred within a predetermined period of time.

5. The apparatus of claim 1 , wherein the processor is further configured to cause the wireless device to:
store cell information for cells encountered by the wireless device that are associated with high movement speed,
wherein the subset of the plurality of frequencies that are prioritized during the cell search comprise cell frequencies from the stored cell information for cells encountered by the wireless device that are associated with high movement speed.

6. The apparatus of claim 1 , wherein the cell search comprises a search for a cell for one of:
a X2L re-selection;
a X2L redirection;
an initial cell selection; or
an out-of-service search.

7. The apparatus of claim 1 , wherein said performing the cell search is performed after a radio link failure event and prior to expiration of a T311 timer.

8. The apparatus of claim 1 , wherein the processor is further configured to cause the wireless device to:
modify one or more radio link monitoring parameters for the wireless device based at least in part on detecting that the wireless device is moving at a high speed.

9. A method, comprising:
by a wireless device:
determining a movement speed of the wireless device; and
performing a cell search in a manner determined based at least in part on the determined movement speed of the wireless device, wherein the cell search comprises scanning a plurality of frequencies for cells within communication range of the wireless device, wherein an order in which the frequencies are scanned is determined based at least in part on the determined movement speed of the wireless device, wherein a subset of the plurality of frequencies are scanned earlier in the order during the cell search when the wireless device is determined to be at a higher movement speed than when the wireless device is determined to be at a lower movement speed.

10. The method of claim 9 , further comprising:
performing radio link monitoring for a serving cell of the wireless device in a manner determined based at least in part on the determined movement speed of the wireless device.

11. The method of claim 10 , wherein performing radio link monitoring further comprises:
selecting a number of out-of-sync indications that triggers initiation of an out-of-sync timer based at least in part on the determined movement speed of the wireless device and further based at least in part on a connected discontinuous reception (CDRX) configuration for the wireless device.

12. The method of claim 10 , wherein performing radio link monitoring further comprises:
selecting an out-of-sync timer length based at least in part on the determined movement speed of the wireless device and further based at least in part on a connected discontinuous reception (CDRX) configuration for the wireless device.

13. The method of claim 10 , wherein performing radio link monitoring further comprises:
selecting a signal quality threshold for determining whether the wireless device is out-of-sync based at least in part on the determined movement speed of the wireless device and further based at least in part on which service type or types are currently active at the wireless device.

14. The method of claim 9 ,
wherein determining the movement speed of the wireless device comprises determining a movement speed state of the wireless device from a plurality of movement speed states.

15. The method of claim 9 , further comprising:
storing cell information for cells that are associated with high movement speed, wherein storing cell information for cells that are associated with high movement speed comprises storing cell frequency information for previous or current serving cells of the wireless device that provide a broadcast indication of being associated with high movement speed.

16. A wireless device, comprising:
an antenna;
a radio operably coupled to the antenna; and
a processor operably coupled to the radio;
wherein the antenna, radio, and processor are configured to:
determine a movement speed of the wireless device; and
perform a cell search, wherein the cell search comprises scanning a plurality of frequencies for cells within communication range of the wireless device, wherein an order in which the frequencies are scanned is determined based at least in part on the determined movement speed of the wireless device, wherein a subset of the plurality of frequencies are scanned earlier in the order during the cell search when the wireless device is determined to be at a higher movement speed than when the wireless device is determined to be at a lower movement speed.

17. The wireless device of claim 16 ,
wherein the subset of the plurality of frequencies that are scanned earlier in the order during the cell search when the wireless device is determined to be at a higher movement speed comprise frequencies associated with cells of one or more high speed train networks.

18. The wireless device of claim 16 , wherein the movement speed of the wireless device is determined based on one or more of:
an amount of doppler shift detected in cellular communication signals received by the wireless device;
a velocity calculation based on information from a global positioning system (GPS) module of the wireless device;
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Assignees

• Apple Inc

Inventors

• Gao Jishan
• Zhong Yong
• Li Shangfeng
• Zhang Lijie
• Miao Qiang
• Zhang Ying
• Yan Yaoqi
• Wang Zhiwei
• Xie Tao
• Qin Junzhen

Classifications

• H04W36/0083

  Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists · CPC title

• H04W48/16 Primary

  Discovering, processing access restriction or access information · CPC title

• H04W4/027

  using movement velocity, acceleration information · CPC title

• H04W64/006

  with additional information processing, e.g. for direction or speed determination · CPC title

• H04W36/305

  Handover due to radio link failure (control signalling for hand-off failure H04W36/0079) · CPC title