GB2446168A

GB2446168A - Reducing the power consumed from a battery

Info

Publication number: GB2446168A
Application number: GB0701724A
Authority: GB
Inventors: Karim El Malki; Paul Collinge
Original assignee: THIRD SENSE Ltd
Current assignee: THIRD SENSE Ltd
Priority date: 2007-01-30
Filing date: 2007-01-30
Publication date: 2008-08-06
Also published as: GB0701724D0

Abstract

Power consumed form a limited capacity power source such as a rechargeable battery is controlled depending on the amount of power stored therein. If a parameter representing the power stored is less than a threshold a controller 19 may identify an application 17,18 and minimise, close or disable its execution, in order to reduce power consumption. The parameter may be a battery lifetime, based on an instantaneous measurement or a predicted value and depend upon time, current voltage and battery resistance. Controller 19 may identify an application or hardware whose execution is to be minimised from a list (fig 4) that can be presented to a user who can instead select a second application, and also set the threshold. A hardware device to be disabled may include a wireless communication device and controller 19 may receive instructions remotely. The controller may be used in a mobile communication device such as a mobile telephone (fig 1) and applications 17,18 may include a message service, a packet radio service or a date service, such as SMS, MMS, GSM and GPRS.

Description

Reducing power consumption

Description

The present invention relates to a method of reducing power consumption in a S device ha ing a]irnited capacity po' er source, such as a rechargeable battery.

Many types of latter\ -powered, processor-driven devices suffer a drawback of limited batters life. Operation of the deviCe can be extcfl(lCd using mains power to recharge the battery and/or to power the device instead of thc battery. 1-Lowever, 1(3 operation of the device can alSo be extended by minirnising power consumption.

For example, in a laptop computer, a power management circuit can he used to minimise power consumption by reducing brightness of a display and/or minimising use of a disk dri\'e.

Limited battery life is a significant problem for mobile telephone handsets because radio freLluencv circuits tend to consume po'ei at a high rate. Nevertheless, there are a number of ways in which power consumption can he minimised. For example, a mobile telephone handset may be switched into a so-called "idle mode" or "standby mode" that reduces the numbei-of signals transmitted or processed.

Furthermore, power consumption of peripheral devices, such as displays and cameras, can also be minimiscd, for example as described in LJS-A-2(i()6/0242441.

However, mobile telephone handsets are increasingly being provided with added features and functionality, such a GPS receivers. Therefore, the problem of limited battery life can be expected to get worse.

The present invention seeks to extend operation of a device having a limited capacity power source.

According to the present invention there is provided a device comprising means for storing power, at least one processing means and means for controlling power consumption operable to determine a parameter dependent upon an amount of power stored by the power storing means, to determine whether the parameter falls below a threshold amount and, in dependence upon the paramctcr falling below the threshold amount, to identify at least one application and to minimise execution of the at least one application by the at least one processing means.

r Since processing means consume less power when idle (i.e. when not performing afl\ instructions), the processing means consume less power and, thus, drain less power from the power storing means, rhereb extending potential operating tirnc.

The at least one processing means may comprise the power consumption controlling means.

The power consumption controlling means ma\ l.)e operable, in dependence upon the parameter falling below the threshold amount, to disable the at least one application. Jhe parameter ma) be a batters' lifetime and the threshold amount ma) / r be a minimum battcr lifetime. The parameter may l.e battcr' voltage. The parameter may be amount ()f energy stored.

The power consumption controlling means ma)' be operable, in dependence upon the parameter falling below the threshold amount, to identify one or more hardware components corresponding to the at least one application and to disable thc at least one hardware component. The at least one hardware component includes means for providing wireless connectivity, sensing means and/or processing means.

The power consumption controlling means may be operable to read a list, from 2 memory, identifying the at least one application. The power consumption controlling means may he operable to present to the user a first set of applications comprising the at least one application. The power consumption controlling means ma be operable, in response to user input, to identify a second set of applications and to minimise execution of the second set of applications instead of the first set of applications.

The power consLimptl( rn controlling means may be operable to set the threshold amount in response to user input. The power consumption controlling means may be opcrnb]e to receive instructions from a remote sourcc. The instructions may specify the threshold amount and/or the at least one application.

The power ConsLimption controlling mcans may he operable to determine the s parameter based on an instantaneous measurement or a plurality of measurements over time. The power consumption controlling means ma\ be configured to predict a aluc of he parameter al a gi en time or a time at which the parameter has a given value.

The parameter may depend on current and time and may be a product of current arid time. The parameter may depend on voltage.

The at least one application ma include a data application, a securit\ application and/or a oice telephony application. The device ma be a mobile communications device.

According to a second aspect of the present invention there is provided a method comprising determining a parameter dependent upon an amount of power stored by a power storing means, determining whether the parameter falls below a threshold amount, in dependence upon the parameter falling below the threshold amount, identifing at least one software application and minimising execution of the at least one software application b) at least ()fle processing means.

According to a third aspect of the present in ention there is provided a computer program comprising Instructions which, when executed by processing means, causes the processing means to execute the method.

According to a fourth aspect of the present invention there is provided a computer readable medium storing the computer program. 3()

hmbodiments of the present invention will now be described, b wa of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic block diagram of a mobile communications dcvice; Figure 2 is a schematic block diagram o functions executed by the mobile comniunications device shown in ligure 1 HgLire 3 is a flo\k diagram of a process carried Out b\ the mobile communications device shown in Figure 1; and Figure 4 illustrates (>plions presented on a diSpla\ of the mobile communications (IC vice.

Referring to Figure 1, an embodiment of device 1 having a limited capacity power source in accordance with the present invention is shown. In this example, the device 1 is a mobile comm unications device capable of exchanging signals through a mobile telephone network and through a wireless local area network.

The device i is p)wered b' a limited capacit power source in the form of a is rechargeable battery 2 and includes a controller 3, a digital signal processor (1)SP) 4, a first radio chipset for providing wireless connectlvii-v to a mobile telephone network, a second radio chipset 5 for providing wireless connectivit\ to a wirc]ess local area network (WLAN), a microphone 6, a speaker 7, a ke\'pad 8, a display 9, a subscriber identity module 10, volatile memory 11, non-volatile memory 12 and a sensor 13, such as a GPS receiver module or a health monitoring sensor, and a camera 14. The rechargeable batters' 2 is charged using a removeably connectable batters' charger 15.

Referring also to Figure 2, the controller 3 loads and executes an operating system 16 and selectively loads and executes applications 17, 17 for managing the mobile telephone network and wireless local area network interfaces and other applications 18, 182 18.

The other applications 181, 182, . . ., 18, includes a voice telephony application, a short, message set-vice (SNIS) application, a multimedia message service (MMS) application and a GSM packet radio system (GPRS) data services application. Ihe applications I 8, 1 8, . . ., 18 may include those that are not perceived by the a user, such as a system monitoring application and an anti-tamper application, an(l those visible to thc user, such as a home entertainment application, a rncdia sharing application, a mobile television application, a video conerencing application and a sensor-related application. The applications 1 8, 1 8 18 may include security applications, such as an antivirus application, a spvware application, an encryption application and/or a radio broadcasting application. The applications l8, 1 8, 18 max' include different versions or levels of application, such as applications providing (litterent levels of securit\ , such as (lifferent le els (if encryption.

The controller 3 loads and executes an application 19 for monitoring and controlling power consumption (hereinafter referred to as the "power controller").

The power controller 19 monitors a parameter dependent upon the amoi.int of power stored in the battcr 2 and disables (or "closes") certain applications 171, 17,, 1 8, 18,..., 18, to reduce the number of instructions executed by the cofltfl)ller 3, t-hereb increasing the amount of rime i-he controller 3 is idle and reducing power /5 consumed. The parameter max' be the amount of power stored or an indicator of the amount (if power stored, such as l)attery voltage or battefl-lifetime. The parameter may he dependent upon other factors, such as power consumption. The applications 17k, 17,, 18, 182,..., 1 8r to be disabled may be chosen according to a predetermined set of rules and/or max' be chosen b the user. The power controller 19 disables an application by instructing the operating system 16 to close the application, for example h clearing the application loaded in volatile memory 11.

In some embodiments, the power controller 19 reduces the number of instructions executed b the controller 3 by allocating fewer clock c des to the application.

ThLiS, the application is not closed, but merely operates more slowly. The power controller 19 ma also instruct other processors, such as the DSP 4, to reduce the number of instructions executed. Certain functions may use both the controller 3 and other processors, such as DSP 4. Thus, disabling or minimising use of a function may save even more power.

Referring also to Figure 3, an embodiment of a method of controlling power consumption will now be described in more detail.

After the devicc I is switched on, the power controller l9 mcasures the battefl power level and checks whether the battery power level falls below a predetermined threshold level (steps Si & S2). For example, remaining l)atter\ power Ah (Ampere hours) may be measured and compared with a remaining batters power threshold.

s The remaining battery power may be determined by measuring current and time, calculating used batters' power, for example by multipl ing current h\ time or b) integrating current over time and sul.)tracl- Ing the used batters' power fr m maximum alue.

Other indicators of power stored nla\ be used. lor example, batters voltage, I, ma be measured and compared with a threshold batters' level, T',,. Thus, the power controller 19 checks whether I -< I. . The predetermined threshold level may be factory set. I Lowever, the user ma set the predetermined threshold level, for example by opening a power control menu (not shown) and specifying or selecting a threshold level. Other indictors include current, temperature and/or resistance, such as l,atrerv resistance.

The threshold level can he expressed in terms of a minimum battefl-lifetime, T,,,, e.g. 15 minutes. A battery lifetime, T can be determined using a measure of energy stored in the battery, F, and consumed power, P. The consumed power, P, may be based on instantaneous use or LISC over a given time, e.g. the preceding hour. The battc lifetime, T, is compared with a threshold batter lifetime, 7',,. Thus, the power controller 19 checks whether T < The threshold level, e.g. threshold battcr level I,, or minimum l)atter\ lifetime T,,,, may be any level set by a manufacturer, netw rk operator, user or System administrator. The level may he set rcmotel\ , e.g. by the operator, wirelesslv or, if the device is connected, via a wired network. For example, the operator ma set different thresholds for different users depending on user characteristics and device use.

If the battery power level does not fall below the predetermined threshold level, then the powcr controller 19 waits for a predetermined tinic interval (step S3) and repeats steps SI and S2.

If, however, the batter power level falls below the predetermined threshold level, then steps are taken to reduce pover consumption.

The power controller 19 reads a list of low-priority applications from non-volatile mcnior 12 (step S4). The list rna be factory set and flay be updated each time a ncw application is installed. Addltionall\ or alternatively, the list may l)C Set by the user, for example b\ opening the power control menu (not shown) and specifying or selecting low-priorit\ applications.

Ihe power control menu (not shown) rna be used to set different operating modes, / each specifying a respective set of functions to be executed. lor example, operating modes may include only voice calls, only voice calls and SMS, and only data and SMS.

The power control menu may provide information regarding battery life according 1-0 whether a particular function is disabled or a particular set of functions are enabled, e.g. if a particular operating mode is selected.

once the power controller 19 receives user input through the power control menu, it prepares and stores a list of low-priority applications in non-volatile memory 12.

The power controller 19 determines whether user interaction feature is enabled (step S5).

If the user interaction feature is enabled, then the power controller 19 presents the Liser with the remaining battcr rime and a suggested list of functions to be disabled (step S6).

Rcfcrring to Figure 4, an cxamplc of an image 21) prescntcd to the user on the display 9 is shown. The image 20 idcnti fics a remaining battcr time 21 and options 22, 22,, 223, 22 to enable/disable a function or set an operating mode, together with corresponding indications 23, 23,, 23 23 of how much longer battery life can be extended. lor example, the options 22, 22, 221, 22 include, "Only cellular (disable \X I AN)'', "( )nI V ice (no data)'', "( )nh data (no voice)' and Nh nimal securlt\ (disable anti\ Irus)" and the corresponding indications of extra batter life arc 15 minutes, 10 mInutes, 1 () nhlnutes and 5 mInutes respectively.

The user mar be given a predetermined amount of time, for example 10 seconds, to respond and modify selections in the list of functions (or modes). ThUS, if the user (locs not respond in time, then the existing selections (i.e. default functions) are disabled. Nowever, if the user modifies any existing selections, then any newly selected functions are disabled. Any newly deselected functions are not disabled.

The remaining power level and/or the threshold power level max' be measured, calculated and/or compared in different ways. Ior example, the power controller 19 may measure battery power level at an instant and compare the batter power level with a threshold value. In some examples, the power controller 19 may measure battery power level continuously or repeatedly over a period of time, calculate an average and compare the average power level with the threshold. For example, the power level ma) be expressed as an average, such as average hatters voltage, < U >, or average batters lifetime, <1>.

2 As explained earlier, battery lifetime can be calculated using power, P. Thus, a batter) time, 7, can be calculated using T = L/P, where L is a measure of energy stored in the battery. th some embodiments, the actual energy stored is not measured or determined, bLit a representative or indicative measure, 1, is used, such as battery voltage. I-ncrg stored ma he calculated or estimated using the representative measure!-, for example b multiplying by a constant, k, i.e. ! = k. I-.

Battery lifetime can be calculai-cd using power a single value of power P(i,) rneasurcd or determined at an instant or using several values of power P(i,), P(i),. . .,P(i) measured or determined over a period of time. Several va]ues of power can be averaged to provide an average power level, <P>.

In some embodiments, 1)atter\ po\ver level ma be monitored and a prediction ma be made as to hen batters level will fall below a threshold, f r example b\ modelling batters power as exponential decay.

Measurements or estimates of power consumption may be used to modif the indications 23, 23,, 23, 234 (Figure 4) of how much longer battery life can be cx tCfl (led.

Referring again to Figure 1 to 3, the user max change which functions should be I disabled (step 57), rbereb\ updating the list of low-priority application (step S8).

Optionally, the list may be stored in non-volatile memory 9.

The power controller 19 disables or minimises use of each function (step S8). For example, the power controller 19 instructs the operating system 16 which 2() applications 171, 17,, 1 8, I 8, 18 to close.

If an application 1 I 7, 18, 1 8 I 8 relies on a peripheral device or hardware component, such as the sensor 13 or camera 14, and has exclusive control over or use of the device or component, then disabling the application 17, I 7, 18, 18, 2 18 may result in the peripheral device becoming redundant. By virtue of the peripheral device or component not consuming power or as a result of disconnecting power to the device, or component, power consumption can be further reduced. For example, if an application for managing a wireless local area network connection is disabled, then the corresponding radio chipsct or card becomes redundant. IhLls, power to the chipset may also be removed.

The power conti-ollcr 1 9 monitors whether the battcry 2 is being rcchargcd (step Sb). If o, then the power Consumption controlling application 19 rc-activatcs (leactiv ated functions (step SI I).

As mentioned earlier, the device 1 includes a plurality of chipsets 5 controlled by respective radio interface applications 1 17,. I Iowever, the device ma onl be pro\ ided with one chipset e.g. a mobile telephone network interface chipset.

if the device I includes plurality of chipsei-s 5, 5, then one radio interface application I 7 may be set as being a default or high-priority application and the other radio interface application(s) is (arc) set as low-priorii-v application(s). The default application l7 can be set l.v the manufacturer or network operator.

Altcrnativcl\ , the default application I7 can be d\'narnicall\ set according to which chipset 5 provides the highest quality recei ed signal and/or uses the least 1 power.

The user may over-ride the power saving measures, for example through the power control menu (not shown).

If the device I is switched off and on again, then the Po'er controller 19 may prompt to user to confirm whether or not they wish to maintain previously-set power saving measures or to terminate them.

it will be appreciated that many modifications rna he made to the eml)odiments bereinl)efore described. For example, the functions of the power controller may be implemented by a dedicated circuit. The functions of the power controller may be integrated into the operating system. The device max' be capable of communicating through only one type of wireless network or more than two types of wireless network. The device need not be a mobile communications device. The device may be any processor-driven, batters -powered or fuel cell-powered device, such as a personal digital assistant (PDA) or a laptop computer. The user interface ma use a voice synthesis/voice recognition interface rather than a display and ke\ pad or touch screen. Kxternal or peripheral devices may be connected to tI)e device and -11 -the powcl-contro]lcr may take these devices and an associated applications into account when determining which applications to disable or otherwise reduce operation thereof. ( )ther forms of energy storage, such as fuel cell, may be used.

The battery may be a lithium-jon battery or ccli. The battery need not be rechargeable.

Claims

1. A device comprisinw means for storing power; at least one proeessrng

means; and means for controlling power consumption operable to determine a parameter dependent upon an amount of power stored b the power storing means, to determine whether the parameter falls below a threshold amount and, in dependence upon the parameter falling below the threshold amount, to identih at w least one application and to minimise execution of the at least one application b' the at least one processing means.

2. A device according to claim 1, wherein the at least one processing means comprises the power consumpnon controlling means.

3. A device according to claim I or 2, wherein the power consumption controlling means is operable, in dependence upon the parameter falling below the threshold amount, to disable the at least one application.

4. A device according to any preceding claim, wherein the parameter a battery lifetime and the threshold amount is a minimum battery lifetime.

5. A device according to an preceding claim, wherein the power consumption controlling means is operable, in dependence upon the parameter falling below the 21 threshold amount, to identify one or more hardware components corresponding to the at least one application and to disable the at least one hardware component.

6. A device according to claim 5, wherein the at least one hardware component includes means for providing wireless connectivii.

7. A device according to claim 5 or 6, wherein the at least one hardware component includes sensing means. -13-

8. A dcvicc according to any one of claims 5 to 8, wherein the at Icast one hardware component includes processing means.

9. A device according to an\ preceding claim, wherein the power Consumption control]ing means is operable to read a list, trom memory, identifying the at least one application.

1 ft A device according to an preceding claim, wherein the power consumption controlling means is operable to present to the user a first set of applications comprising the at least OflC application.

11. A device according to claim I 0, wherein thc power consumption controlling means is operable, in responsc to user input, to idcntif a second set of applications and to minimise execution of the second set of applications instead of the first set / S Of applications.

12. A device according to claim 10 or 11, wherein the power consumption controlling means is operable to set the threshold amount in response to user input.

13. A device according to any preceding claim, wherein the power consumption controlling means is operable to receive Instructions from a remote source.

14. A device according to claim 13, wherein the instructions specify the threshold amount.

15. A device according to claim 13 or 14, wherein the instructions specify the at least one application.

16. A device according to an preceding claim, wherein the power consumption 3() controlling means is conhgured to determine the parameter based on an instantaneous measurement. -14-

17. A device according to any preceding claim, wherein the power Consumption controlling means is conhgurcd to determine thc para11eter based on a p]urahtv (.)f measurement o er time.

18. A device according to any preceding claim, wherein the power consumption controlling means is configured to predict a value of the parameter at a given time r a time at which the parameter has a given value.

19. A device according to any preceding claim, wherein the parameter depends on current and time.

20. A device according to claim 19, wherein the parameter is a product of cut-rent and time.

i

21. A device according to an preceding claim, wherein the parameter depends on voltage.

22. A device according to any preceding, wherein the parameter depends on batters resistance.

23. A device according to any preceding claim, wherein the at least one application include a data application.

24. A device according to any preceding claim, wherein the at least one application include a security application.

25. A device according to any preceding claim, wherein the at least one application includeav olce telephony application.

26. A device according to am preceding claim, which is a mobile communications device. -15-

27. A device comprising: a battery; at least one processor; and ii control unit operable to dctcrmine a parameter dependent upon an afliount ot power store.d by the power storing means, to determine whctber the parametcr falls below a threshold amount and, in dependence upon the parameter falling belo the threshold amount, to identi f at least)ne application and to minimise execution of the at least one application by the at least one processing means.

28. A method comprising: determining a paraneter dependent upon an amount of power stored by a po'ct storing means; determining whether the parameter falls below a threshold amount; in dependence upon the parameter falling below the threshold amount, / identif ing at least one software application; and minirnising execLition of the at least one software application b at least OflC processing means.

29. A computer program comprising instructions which, when executed by 2() processing means, causes the processing means to perform the method of claim 28.

30. A computer readable medium storing a computer program according to claim 29.

2

3 1. A device substantially as described with reference to Figures 1 to 4 of the accompanying drawings.

32. A method substantially as described with reference to Figures 1 to 4 of the accompanying drawings.