Cell selection offset used to indicate wireless cell unsuitable for communications
View Patent ↗Embodiments disclosed herein provide systems and methods for compelling a cell selection metric to indicate that a wireless cell is not suitable for communications. In a particular embodiment, a method provides receiving system information from a base station of a visited wireless communication network. The method further provides calculating a cell selection metric from cell selection parameters within the system information and a cell selection offset stored in the wireless communication device, wherein the cell selection offset causes the cell selection metric to indicate an unsuitable wireless cell. The method further provides receiving a request for a data connection from an application executing on the wireless communication device and, in response to the request, recalculating the cell selection metric from the cell selection parameters without the cell selection offset. The method further provides determining whether the wireless cell is suitable for communications based on the cell selection metric.
1. A method of operating a wireless communication device, comprising:
receiving system information from a base station of a visited wireless communication network, wherein the system information includes at least a portion of cell selection parameters for a wireless cell of the base station;
calculating a cell selection metric from the cell selection parameters and a cell selection offset stored in the wireless communication device, wherein the cell selection offset causes the cell selection metric to indicate that the wireless cell is not suitable for communications;
receiving a request for a data channel from an application executing on the wireless communication device;
in response to the request, recalculating the cell selection metric from the cell selection parameters without the cell selection offset; and
determining whether the wireless cell is suitable for communications based on the recalculated cell selection metric.
2. The method of claim 1 , further comprising:
if the wireless cell is not suitable for communications based on the cell selection metric, calculating a second cell selection metric from second cell selection parameters for a second wireless cell from a second base station; and
selecting the second wireless cell if the second cell selection metric indicates that the second wireless cell is suitable for communications.
3. The method of claim 2 , wherein a home wireless communication network comprises the second base station.
4. The method of claim 1 , wherein the wireless cell uses a Long Term Evolution (LTE) protocol.
5. The method of claim 1 , wherein the cell selection parameters comprise:
a measured received power level value (Q rxlevmeas ) for the wireless cell as measured by the wireless communication device;
a minimum required received power level value (Q rxlevmin ), wherein Q rxlevmin is included in the system information;
a compensation power level (P compensation ), wherein the compensation power level equals the maximum of P EMAX −P UMAX or 0, wherein P EMAX is the maximum power the wireless communication device is allowed to transmit in the wireless cell and P UMAX is the maximum power the wireless communication device is allowed to transmit according to a power class of the wireless communication device, and wherein both P EMAX and P UMAX are included in the system information.
6. The method of claim 5 , wherein calculating the cell selection metric uses the following equation:
the cell selection metric(Srxlev)=Q rxlevmeas −(Q rxlevmin +the cell selection offset)−P compensation .
7. The method of claim 6 , wherein determining whether the wireless cell is suitable for communications based on the cell selection metric, comprises:
determining that the wireless cell is suitable for communications if Srxlev is greater than 0; and
determining that the wireless cell is not suitable for communications if Srxlev is less than or equal to 0.
8. The method of claim 7 , wherein the cell selection offset comprises a value that causes the Srxlev to be less than or equal to 0.
9. The method of claim 1 , further comprising:
after the application is done using the data channel, recalculating the cell selection metric from the cell selection parameters with the cell selection offset.
10. The method of claim 1 , wherein a user of the wireless communication device is actively using the application.
11. A wireless communication device, comprising:
a wireless communication interface configured to receive system information from a base station of a visited wireless communication network, wherein the system information includes at least a portion of cell selection parameters for a wireless cell of the base station;
a processing system configured to calculate a cell selection metric from the cell selection parameters and a cell selection offset stored in the wireless communication device, wherein the cell selection offset causes the cell selection metric to indicate that the wireless cell is not suitable for communications, receive a request for a data channel from an application executing on the wireless communication device, in response to the request, recalculate the cell selection metric from the cell selection parameters without the cell selection offset, and determine whether the wireless cell is suitable for communications based on the recalculated cell selection metric.
12. The wireless communication device of claim 11 , further comprising:
the processing system further configured to, if the wireless cell is not suitable for communications based on the cell selection metric, calculate a second cell selection metric from second cell selection parameters for a second wireless cell from a second base station and select the second wireless cell if the second cell selection metric indicates that the second wireless cell is suitable for communications.
13. The wireless communication device of claim 12 , wherein a home wireless communication network comprises the second base station.
14. The wireless communication device of claim 11 , wherein the wireless cell uses a Long Term Evolution (LTE) protocol.
15. The wireless communication device of claim 11 , wherein the cell selection parameters comprise:
a measured received power level value (Q rxlevmeas ) for the wireless cell as measured by the wireless communication device;
a minimum required received power level value (Q rxlevmin ), wherein Q rxlevmin is included in the system information;
a compensation power level (P compensation ), wherein the compensation power level equals the maximum of P EMAX −P UMAX or 0, wherein P EMAX is the maximum power the wireless communication device is allowed to transmit in the wireless cell and P UMAX is the maximum power the wireless communication device is allowed to transmit according to a power class of the wireless communication device, and wherein both P EMAX and P UMAX are included in the system information.
16. The wireless communication device of claim 15 , wherein the processing system is configured to calculate the cell selection metric uses the following equation:
the cell selection metric(Srxlev)=Q rxlevmeas −(Q rxlevmin +the cell selection offset)−P compensation .
17. The wireless communication device of claim 16 , wherein the processing system is configured to determine whether the wireless cell is suitable for communications based on the cell selection metric by:
determining that the wireless cell is suitable for communications if Srxlev is greater than 0; and
determining that the wireless cell is not suitable for communications if Srxlev is less than or equal to 0.
18. The wireless communication device of claim 17 , wherein the cell selection offset comprises a value that causes the Srxlev to be less than or equal to 0.
19. The wireless communication device of claim 11 , further comprising:
the processing system configured to, after the application is done using the data channel, recalculate the cell selection metric from the cell selection parameters with the cell selection offset.
20. The wireless communication device of claim 11 , wherein a user of the wireless communication device is actively using the application.