Method, apparatus and computer program for limiting the total transmit power of a wireless device
View Patent ↗A wireless device has a plurality of radio systems. The current priority of each of the radio systems is determined. An upper bound for the transmit power of each of the radio systems is set in dependence on at least the current priorities of the radio systems and a current maximum permitted transmit power of the wireless device. The upper bounds for the transmit power of each of the radio systems are variable over time and are set such that the sum of the upper bounds does not exceed the current maximum permitted transmit power of the wireless device. For each of the radio systems, the transmit power of that radio system is limited such that the respective upper bound for the transmit power for that radio system is not exceeded.
1. A method of limiting a total transmit power of a wireless device having a plurality of radio systems that each provide service for a different SIM of the wireless device, the method comprising:
determining a current priority of each of the plurality of radio systems that provide service for the different SIMs;
setting an upper bound for transmit power of each of the plurality of radio systems in dependence on at least the current priorities of the plurality of radio systems and a current maximum permitted transmit power of the wireless device, the upper bounds for the transmit power of each of the plurality of radio systems being variable over time and being set such that a sum of the upper bounds does not exceed the current maximum permitted transmit power of the wireless device, the total transmit power of the wireless device at any time being a sum of the transmit powers of the plurality of radio systems at that time; and,
for each of the plurality of radio systems, limiting the transmit power of that radio system such that the respective upper bound for the transmit power for that radio system is not exceeded.
2. The method according to claim 1 , wherein the transmit power of each of the plurality of radio systems is limited to its respective upper bound for a predetermined limitation period, and after the predetermined limitation period has passed, the method comprises:
determining a new current priority of each of the plurality of radio systems;
setting a new upper bound for the transmit power of each of the plurality of radio systems in dependence on the new current priorities of the plurality of radio systems and the current maximum permitted transmit power of the wireless device; and,
for each of the plurality of radio systems, limiting the transmit power of that radio system for the predetermined limitation period, such that the determined new upper bound for the transmit power for that radio system is not exceeded within that predetermined limitation period.
3. The method according to claim 2 , wherein an average transmit power of the wireless device, averaged over a predetermined period of time, cannot exceed a predetermined power, and the method comprises determining the current maximum permitted transmit power of the wireless device at the start of each limitation period in dependence upon said predetermined power and the previous transmit power of the wireless device.
4. The method according to claim 1 , wherein the current maximum permitted transmit power of the wireless device is fixed and cannot exceed a predetermined power at any time.
5. The method according to claim 1 , wherein the priority of each of the plurality of radio systems is determined according to at least one of:
whether the radio system is supporting circuit switched or packet switched services;
whether the radio system is supporting real-time or non-real-time services;
a pre-defined priority of the SIM for which the radio system provides service;
quality of service requirements of the service supported by the radio system; and
the priority of the service supported by the radio system.
6. The method according to claim 1 , wherein a radio system providing a circuit switched service is determined to have a higher priority than a radio system providing a packet switched service.
7. The method according to claim 1 , wherein a radio system providing a real-time service is determined to have higher priority than a radio system providing a non-real-time service.
8. The method according to claim 1 , wherein, in the event that a first radio system is determined to have a higher priority than a second radio system, then the upper bound on the transmit power of the first radio system is set to be higher than the upper bound on the transmit power of the second radio system.
9. The method according to claim 1 , wherein the setting of the upper bounds on the transmit powers of the plurality of radio systems is also dependent upon the mean current powers of each of the plurality of radio systems, the mean current power of a radio system being the average transmit power used by that radio system over a period of time immediately preceding the current time.
10. The method according to claim 9 , wherein, in the event that it is determined that one of the plurality of radio systems has the highest priority, the upper bound on the transmit power of that radio system is set to be the lowest value out of:
(i) the current maximum permitted transmit power of the wireless device less a predetermined minimum back-off, and
(ii) the sum of the mean current power of that radio system and a headroom, wherein the headroom is determined according to a predicted power variation of that radio system over the period of time for which the upper bound will be applied.
11. The method according to claim 1 , wherein the current maximum permitted transmit power is determined in dependence upon at least one of:
a current temperature of the device;
a maximum electrical current that can be drawn from a battery of the wireless device;
legal limitations on the transmit power of the wireless device; and
a current status of a battery of the wireless device.
12. An apparatus for limiting a total transmit power of a wireless device, the apparatus comprising at least one processor, and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to:
determine a current priority of each of a plurality of radio systems of the wireless device, each of the plurality of radio systems providing service for a different SIM of the wireless device;
set an upper bound for transmit power of each of the plurality of radio systems in dependence on at least the current priorities of the plurality of radio systems and a current maximum permitted transmit power of the wireless device, the upper bounds for the transmit power of each of the plurality of radio systems being variable over time and being set such that a sum of the upper bounds does not exceed the current maximum permitted transmit power of the wireless device, the total transmit power of the wireless device at any time being a sum of the transmit powers of the plurality of radio systems at that time; and,
for each of the plurality of radio systems, limit the transmit power of that radio system such that the respective upper bound for the transmit power for that radio system is not exceeded.
13. The apparatus according to claim 12 , wherein the transmit power of each of the plurality of radio systems is limited to its respective upper bound for a predetermined limitation period, and the apparatus is arranged to, after the predetermined limitation period has passed:
determine a new current priority of each of the plurality of radio systems;
set a new upper bound for the transmit power of each of the plurality of radio systems in dependence on the new current priorities of the plurality of radio systems and the current maximum permitted transmit power of the wireless device; and,
for each of the plurality of radio systems, limit the transmit power of that radio system for the predetermined limitation period, such that the determined new upper bound for the transmit power for that radio system is not exceeded within that predetermined limitation period.
14. The apparatus according to claim 13 , wherein an average transmit power of the wireless device, averaged over a predetermined period of time, cannot exceed a predetermined power, and the apparatus is arranged to determine the current maximum permitted transmit power of the wireless device at the start of each limitation period in dependence upon said predetermined power and the previous transmit power of the wireless device.
15. The apparatus according to claim 12 , wherein the current maximum permitted transmit power of the wireless device is fixed and cannot exceed a predetermined power at any time.
16. The apparatus according to claim 12 , wherein the priority of each of the plurality of radio systems is determined according to at least one of:
whether the radio system is supporting circuit switched or packet switched services;
whether the radio system is supporting real-time or non-real-time services;
a pre-defined priority of the SIM for which the radio system provides service;
quality of service requirements of the service supported by the radio system; and
the priority of the service supported by the radio system.
17. The apparatus according to claim 12 , wherein a radio system providing a circuit switched service is determined to have a higher priority than a radio system providing a packet switched service.
18. The apparatus according to claim 12 , wherein a radio system providing a real-time service is determined to have higher priority than a radio system providing a non-real-time service.
19. The apparatus according to claim 12 , wherein, in the event that a first radio system is determined to have a higher priority than a second radio system, then the upper bound on the transmit power of the first radio system is set to be higher than the upper bound on the transmit power of the second radio system.
20. The apparatus according to claim 12 , wherein the setting of the upper bounds on the transmit powers of the plurality of radio systems is also dependent upon the mean current powers of each of the plurality radio systems, the mean current power of a radio system being the average transmit power used by that radio system over a period of time immediately preceding the current time.
21. The apparatus according to claim 20 , wherein, in the event that it is determined that one of the plurality of radio systems has the highest priority, the upper bound on the transmit power of that radio system is set to be the lowest value out of:
(i) the current maximum permitted transmit power of the wireless device less a predetermined minimum back-off, and
(ii) the sum of the mean current power of that radio system and a headroom, wherein the headroom is determined according to a predicted power variation of that radio system over the period of time for which the upper bound will be applied.
22. The apparatus according to claim 12 , wherein the current maximum permitted transmit power is determined in dependence upon at least one of:
a current temperature of the wireless device;
a maximum electrical current that can be drawn from a battery of the wireless device;
legal limitations on the transmit power of the wireless device; and
a current status of a battery of the wireless device.
23. A non-transitory computer-readable storage medium comprising a set of computer-readable instructions for limiting a total transmit power of a wireless device such that when the computer program is executed on a computing device of the wireless device having a plurality of radio systems that each provide service for a different SIM of the wireless device, the computing device is arranged to:
determine a current priority of each of the plurality of radio systems that provide service for the different SIMs;
set an upper bound for the transmit power of each of the plurality of radio systems in dependence on at least the current priorities of the plurality of radio systems and a current maximum permitted transmit power of the wireless device, the upper bounds for the transmit power of each of the plurality of radio systems being variable over time and being set such that a sum of the upper bounds does not exceed the current maximum permitted transmit power of the wireless device, the total transmit power of the wireless device at any time being a sum of the transmit powers of the plurality of radio systems at that time; and,
for each of the plurality of radio systems, limit the transmit power of that radio system such that the respective upper bound for the transmit power for that radio system is not exceeded.