Abstract:
There is provided a method of adjusting power consumption by a wireless device having a codec and a battery, where the codec has a plurality of states of operation and the battery has a plurality of power levels. The method comprises operating the wireless device at a first power level of the plurality of power levels and a first state of the plurality of states of operation, while in communication with a remote device; receiving a power level indication indicative of a second power level of the plurality of power levels; selecting a second state of the plurality of states of operation for the codec corresponding to the second power level of the plurality of power levels; and modifying the codec to operate at the second state of the plurality of states of operation.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to wireless telephones and, more particularly, to extending the battery life for wireless telephones by adapting power consumption.  
         [0003]     2. Background Art  
         [0004]     An essential aspect of mobile communications is the generation and consumption of power. Power is one of the most precious commodities for wireless communications. Today, many are in pursuit of ways to provide longer lasting batteries, and to design devices that use less power allowing for wireless phones to operate with less frequent needs for a battery recharge.  
         [0005]     Various techniques, both hardware and software, have been proposed to reduce the power consumption for wireless phones. For example, some software-level techniques have concentrated on non-communication components of the wireless phone, such as the display and the CPU. More specifically, the display may be turned off after some period of inactivity or the CPU may be slowed down or stopped depending on its workload. Hardware-level solutions for managing the wireless phone focus on modulating the power used by the wireless phone transmitter during active communication.  
         [0006]     In view of the recent increase in the demand for wireless phones, many have first-hand experience with untimely depletion of wireless phone batteries. Quite often, users must either shorten wireless phone communications and rapidly end the communication due to the wireless phone battery being low, or the wireless phone communication is abruptly terminated and lost due to the wireless phone battery being completely depleted. In many instances, wireless phone users would appreciate having the ability to extend the communications period in exchange for reduced feature sets. For example, during an emergency call, such as a  911  call, wireless phone users would indeed prefer to disable any nonessential power-consuming feature of the wireless phone in order to extend the communications period.  
         [0007]     Accordingly, there is still an intense need in the art for methods and systems to adapt power consumption to extend the battery life such that wireless telephone communications can continue for a longer period of time.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention is directed to extending the battery life of wireless telephones by adapting power consumption. In one aspect of the present invention, there is provided a method of adjusting power consumption by a wireless device having a codec and a battery, where the codec has a plurality of states of operation and the battery has a plurality of power levels. The method comprises operating the wireless device at a first power level of the plurality of power levels and a first state of the plurality of states of operation, while in communication with a remote device; receiving a power level indication indicative of a second power level of the plurality of power levels; selecting a second state of the plurality of states of operation for the codec corresponding to the second power level of the plurality of power levels; and modifying the codec to operate at the second state of the plurality of states of operation. The wireless device can be a wireless telephone and the codec can be a voice codec. In other aspects, the codec can be a video codec.  
         [0009]     In one aspect, the second power level is lower than the first power level, and the second state consumes less power than the first state. In a further aspect, the codec operates at a lower average bit rate in the second state than in the first state. Yet, in other aspects, the codec has a plurality of modes, wherein in the first state, the codec operates in a first mode of plurality of modes, wherein in the second state, the codec operates in a second mode of plurality of modes, and wherein the second mode consumes less power than the first mode.  
         [0010]     In another aspect, second power level is higher than the first power level, and the second state consumes more power than the first state. For example, the codec may operate at a higher average bit rate in the second state than in the first state.  
         [0011]     In a separate aspect of the invention, there is also provided a wireless device having adaptable power consumption. The wireless device comprises a battery having a plurality of power levels; a codec having a plurality of states of operation; and a power management module configured to monitor a power level of the battery and provide a power level indication to the codec based on the power level. The wireless device operates at a first power level of the plurality of power levels and a first state of the plurality of states of operation, while in communication with a remote device, and wherein the power management module provides the power level indication to the codec indicative of a second power level of the plurality of power levels, and wherein the codec selects a second state of the plurality of states of operation corresponding to the second power level of the plurality of power levels and modifies the codec to operate at the second state of the plurality of states of operation.  
         [0012]     Other features and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The features and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, wherein:  
         [0014]      FIG. 1  illustrates a block diagram of a wireless telephone with adaptable power consumption, according to one embodiment of the present invention; and  
         [0015]      FIG. 2  illustrates a flow diagram for adapting power consumption of the wireless telephone of  FIG. 1 , according to one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     The present invention is directed to extending the battery life of wireless telephones by adapting power consumption. Although the invention is described with respect to specific embodiments, the principles of the invention, as defined by the claims appended herein, can obviously be applied beyond the specifically described embodiments of the invention described herein. For example, although the invention is described with reference to wireless telephones, the invention is not limited to such devices or systems and can be used in conjunction with any device or system that comprises an encoding scheme, e.g. voice codec, video codec, image codec, etc. Moreover, in the description of the present invention, certain details have been left out in order to not obscure the inventive aspects of the invention. The details left out are within the knowledge of a person of ordinary skill in the art.  
         [0017]     The drawings in the present application and their accompanying detailed description are directed to merely example embodiments of the invention. To maintain brevity, other embodiments of the invention which use the principles of the present invention are not specifically described in the present application and are not specifically illustrated by the present drawings. It should be borne in mind that, unless noted otherwise, like or corresponding elements among the figures may be indicated by like or corresponding reference numerals.  
         [0018]      FIG. 1  illustrates a block diagram of wireless telephone  100  with adaptable power consumption, according to one embodiment of the present invention. As shown, wireless telephone  100  includes RF (Radio Frequency) module  110 , where the radio frequency signal is filtered and downconverted to analog baseband signals in one direction, and in the other direction, analog baseband signals are filtered and then upconverted and amplified to generate radio frequency signals. In addition, wireless telephone  100  includes analog baseband module  115 , where analog baseband signals received from RF module  110  are filtered, sampled and digitized before being fed to DSP/microprocessor  140 . Further, analog baseband module  115  receives coded speech digital signal from codec  120 , and samples and converts coded speech digital signal to analog baseband signals, which are provided to RF module  110  for transmission over antenna  105 . Codec  120  can be a voice coder that receives a speech signal from microphone  122 , and digitizes and codes the speech signal according to a voice coding scheme, such as Selectable Mode Vocoder (SMV), VMR-WB cdma2000, and the like. Codec  120  also receives a digitized and coded speech for decoding and transmission to speaker  123 . Codec  120  can include a source-protection encoding and decoding module and a channel-protection encoding and decoding module (not shown), which are known to those of ordinary skill in the art. The digital signal processor (DSP) portion of DSP/microprocessor  140  is known in the art to perform signal manipulations and calculations at high speed. Whereas, the microprocessor portion of DSP/microprocessor  140  is known in the art to control the user interface, such as keypad  150  and display  155 . The microprocessor is further used to coordinate the wireless phone functions and components. Memory  145  may include ROM, RAM, Flash memory, and the like, and provides storage space for the operation of wireless phone  100 . Memory  145  may be used by DSP/microprocessor  140  for storing and retrieving information during the operation of wireless phone  100 , as well as customizable features of wireless phone  100 , such as a phone directory, ringer, etc. As shown, wireless phone  100  also includes battery  135  for providing power to wireless phone  100 . Battery  135  can be recharged using a charger (not shown), which is known in the art. Power management  125  of wireless phone  100  regulates the power received from battery  135  for distribution in wireless phone  100 .  
         [0019]     Turning to codec  120  of wireless phone  100 , as stated above, codec  120  may include coding schemes at various average bit rates and various complexities. For example, in one embodiment, codec  120  may operate according to the SMV speech coding scheme, which includes several modes of operation having different average data rates (ADRs), and which is described in 3 rd  Generation Partnership Project 2 “3GPP2” Specification, entitled “Selectable Mode Vocoder Service Option for Wideband Spread Spectrum Communication Systems,” Version 2, dated December 2001, which is hereby incorporated by reference in its entirety. As described in the SMV specification, SMV includes three main modes of operation, where the first mode or mode 0 has a higher average bit rate than the second mode or mode 1 and is designed to achieve a higher quality than mode 1; and mode 1 has a higher average bit rate than the third mode or mode 2 and is designed to achieve a higher quality than mode 2. Other modes of operation have also been designed for SMV, such as special modes of modes 0 and 1, where the maximum allowable rate is the half rate, and these new modes are referred to as modes 4 and 5, respectively. SMV has full rate at 8.55 kbps, half rate at 4.0 kbps, quarter rate at 2.0 kbps and eighth rate at 0.8 kbps.  
         [0020]     In one embodiment of the present invention, power management  125  includes battery level indicator  130 , which indicates a power level based on remaining battery power. For example, the battery level can be indicated by numbers 0-15, where 0 indicates that the battery is completely depleted, and 15 indicates that the battery is completely full. As shown, battery level indicator  130  is in communication with operation controller  121  of codec  120 . Operation controller  121  adapts the operation of codec  120  according to the battery level indicated by battery level indicator. For example, if battery level indicator  130  indicates that the battery level has decreased, operation controller  121  may select a state of operation for codec  120  that consumes less power in order to increase the life of battery  135 . To reduce power, operation controller  121  may reduce average bit rate of codec  120 . For example, if codec  120  is operating at mode 0, the average bit rate may be reduced if the codec is switched to mode 1.  
         [0021]     It should be noted that the average transmit power, which is the power consumed by RF module  110 , is directly proportional to the average bit rate. In other words, the lower the average bit rate, the lower the average transmit power, which results in less power consumption by RF module  110 . For example, lowering the average bit rate lowers the average transmit power for given cell constellation and user location within the cell. Although a cell phone at the borderline of a given cell or in a heavily congested cell might requires a higher power than a cell phone closer to the center of a given cell or in a lightly utilized cell, it still remains that switching to a lower average bit rate will reduce the power needed to maintain the connection in a particular cell/user scenario.  
         [0022]     In another embodiment, the average bit rate may be maintained, but complexity of the coding scheme may be reduced to conserve power. Yet, in other embodiments, operation controller  121  may use a table for corresponding the battery level indicator received from battery level indicator  130  to a state of operation of codec  120 . For example, the state of operation can be based on both the average bit rate and complexity of the coding scheme. In an embodiment that operates according to the SMV speech coding scheme, operation controller  121  may switch from one SMV mode to another based on the battery level. In addition, if battery  135  is being charged, battery level indicator  130  may indicate an increase in power. In such event, operation controller  121  may select a mode of SMV that consumes more power and/or increases complexity of the coding scheme, which provides a superior voice quality.  
         [0023]     It should be noted that similar scheme is applicable to other coding schemes that may be utilized by codec  120 . As an example, the VMR-WB speech coding scheme, which also includes various modes of operation and average bit rates, is described in 3GPP2 Specification, entitled “Source-Controlled Variable-Rate Multimode Wideband Speech Codec (VMR-WB) Service Option 62 for Spread Spectrum Systems”, Version 1.0, dated July 2004, which is hereby incorporated by reference in its entirety. As described in the VMR-WB specification, it includes four main modes of operation, where the first mode or mode 0, is designed to achieve better quality than 3GPP/AMR-WB at 14.25 kbps; the second mode or mode 1, is designed to achieve better quality than 3GPP/AMR-WB at 12.65 kbps; the third mode or mode 2, is designed to achieve better quality than 3GPP/AMR-WB at 8.85 kbps; and the fourth mode or mode 3, is designed to achieve better quality than 3GPP/AMR-WB at 12.65 kbps. The VMR-WB speech coding scheme has full rate at 13.3 kbps, half rate at 6.2 kbps, quarter rate at 2.7 kbps and eighth rate at 1.0 kbps.  
         [0024]     As stated above, if battery level indicator  130  indicates that the battery level has decreased, operation controller  121  may select a state of operation for codec  120  that consumes less power in order to increase the life of battery  135 , such as reduction of average bit rate for the VMR-WB coder, reduce complexity of the coding scheme and/or switch from one VMR-WB mode to another, e.g. from mode 0 to mode 2.  
         [0025]      FIG. 2  illustrates flow diagram  200  for adapting power consumption of wireless telephone  100 , according to one embodiment of the present invention. At step  205 , according to one embodiment, there is provided a state table that includes various states of operation of codec  120  arranged according to the amount of power consumption by codec  120  in each state. In one embodiment, the state able can be arranges based on average bit rates, which can be directly proportional to power consumption. In another embodiment, the state table could be more complex and be arranged based on a combination of average bit rate and complexity of coding scheme. For example, it is possible for a complex 4.0 kbps coder to consume more power than a 8.5 kbps coder. Yet, in other embodiment, the table can be arranged according to one of multi-modes of operation of the codec, such as modes 0-3 of the VMR-WB coder.  
         [0026]     Next, at step  210 , wireless phone  100  receives a request to establish a wireless phone communication. At step  215 , wireless phone  100  may select a first state of operation that is selected from the state table based on the battery level indication. For example, in one embodiment using SMV, if battery level indicator indicates that the battery level is low, e.g. 2 out of 15, operation controller  121  of codec  120  may limit codec  120  to a low average bit rate of mode 1 state of operation or a low complexity 4.0 kbps state of operation. Yet, in another embodiment using VMR-WB cdma2000, lower average bit rate mode 1 of VMR-WB may be selected by operation controller  121 , as the state of operation.  
         [0027]     At step  220 , wireless telephone  100  establishes a wireless telephone communication according to the first state selected in step  210 . Next, battery level indicator  130  provides updated indications to operation controller  121  at step  225 , where battery  135  level is monitored to determine whether battery  135  power has decreased or increased. For example, if battery  135  power has increased due to battery  135  being charged while wireless telephone  100  is in operation, the process moves to step  235 , where operation controller  221  may select a second state of operation to improve the voice quality, which increases power consumption, e.g. change VMR-WB mode 1 to mode 0, increase the average bit rate and/or increase complexity. Yet, if battery  135  power decreases due to battery  135  power being depleted, as wireless telephone  100  continues its operation, the process moves to step  230 , where operation controller  221  may select a second state of operation to further decrease power consumption, e.g. change VMR-WB mode 1 to mode 2, reduce the average bit rate and/or reduce complexity, in order to increase communication time.  
         [0028]     Although the present invention is described with reference to voice codecs; however, as stated above, the present invention can be utilized in conjunction with systems using video codecs, image codecs, and the like. For example, if a video clip is being encoded at a first average bit rate, the first average bit rate may be reduced to a second average bit rate if the battery level indicator indicates a lower battery level. Similarly, the average bit rate of an image codec may be reduced as the battery level decreases to save more power. In fact, for video and image transmission applications, the average bit rate can be initially set and adjusted based on a combination of the battery level and the size of the data that is being transmitted to provide a desired tradeoff between the quality and the quantity of the video and image transmitted given the battery level and the data size.  
         [0029]     From the above description of the invention it is manifest that various techniques can be used for implementing the concepts of the present invention without departing from its scope. Moreover, while the invention has been described with specific reference to certain embodiments, a person of ordinary skill in the art would recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. For example, it is contemplated that the circuitry disclosed herein can be implemented in software, or vice versa. The described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the invention is not limited to the particular embodiments described herein, but is capable of many rearrangements, modifications, and substitutions without departing from the scope of the invention.