Abstract:
An electronic device and a power saving method thereof are provided. The electronic device includes a network module and a power saving module, wherein the network module connects to an access point (AP). The method includes executing an AP search operation at a predetermined time interval by the network module, and determining whether the electronic device is in a specific state by the power saving module. The method also includes disabling the network module from executing the AP search operation as long as the electronic device is still in the specific state. As a result, the unnecessary AP search operations can be avoided, and the purpose of saving power can be achieved.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority benefit of U.S.A. provisional application Ser. No. 61/265,339, filed on Nov. 30, 2009, all disclosures are incorporated therewith. This application also claims the priority of Taiwan application serial no. 99133886, filed on Oct. 5, 2010. All disclosure of the Taiwan application is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a power saving method of an electronic device, and more particularly to a power saving method of an electronic device having network connection function. 
         [0004]    2. Description of Related Art 
         [0005]    Along with the rapid advancement of the Internet, the information transmission medium is not limited to newspapers, periodicals and the television media. Nowadays, people may retrieve the required information from a network. People may also use the network to conduct social, recreational or commercial transaction activities. As the wireless network technology continues to improve, the time and place of using a network are no longer being limited as long as the electronic products are capable of connecting to a wireless network. 
         [0006]    A wireless network interface card is an indispensable device for an electronic product to connect to a wireless network. According to the standard specifications of local area network, prior to connecting to any access point (AP), it is mandated for the wireless network interface card to execute an AP search operation at a first predetermined time interval (a duration of about 60 second) to identify the AP in the environment that is appropriate for connection. The execution of each AP search operation requires approximately 8 seconds. 
         [0007]    After the wireless network interface card connects to an AP, as shown in  FIG. 1 , the wireless network interface card still executes the AP search operation (for example, the AP search operations  110 ,  120 ,  130 ) at the first predetermined time interval T 1  (a duration of about 60 second). Moreover, in order to ensure the wireless network interface card is connected to the AP, the wireless network interface card sends an ACK signal, which uses up about 0.03 second, for every second predetermined time interval (a duration of about 0.1 to 1 second) to the currently connected AP and bases on a beacon correspondingly feedback from the AP. 
         [0008]    As shown in  FIG. 1 , each AP search operation that is being executed after the wireless network interface card is connected to the AP is for the purpose of preventing the wireless network interface card from being disconnected with the currently connected AP due to displacement or other reasons. However, when the connection between the wireless network interface card and the AP is stable, the AP search operation is expendable and undue power consumption is resulted. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to a power saving method in which the electronic device is obviated from any unnecessary access point (AP) search operation to lower power loss. 
         [0010]    The present invention provides an electronic device, wherein any unnecessary AP search operation is reduced to improve power saving. 
         [0011]    The present invention provides a power saving method, applicable in an electronic device having a network module and a power saving module, wherein the network module connects to an AP. In the method, the network module executes an AP search operation at a predetermined time interval and the power saving module determines whether the electronic device is in a specific state. When the electronic device is/maintains in the specific state, the power saving module disables the network module from executing the AP search operation. 
         [0012]    According to an exemplary embodiment of the disclosure, whether the electronic device is in the specific state is determined according to a quality of service between the network module and the AP. 
         [0013]    According to an exemplary embodiment of the disclosure, the step of determining whether the electronic device is in the specific state according to the quality of service between the network module and the AP includes: whenever the network module receives a beacon from the AP, a received signal strength indication (RSSI) of the AP is obtained. When the RSSI is greater than a first threshold value, it is determined that the electronic device is in the specific state. 
         [0014]    According to the exemplary embodiment of the disclosure, the step of determining whether the electronic device is in the specific state according to the quality of service between the network module and the AP includes: whenever the network module receives a beacon from the AP, a signal to noise rate (SNR) is calculated. When the SNR is greater than a second threshold value, it is determined that the electronic device is in the specific state. 
         [0015]    According to an exemplary embodiment of the disclosure, wherein the step of determining whether the electronic device is in the specific state includes when the electronic device enters an idle mode, it is determined that the electronic device is in the specific state. 
         [0016]    According to an exemplary embodiment of the disclosure, the power saving method further includes when the electronic device is not in the specific state, the network module is allowed to perform the AP search operation at the predetermined time interval. 
         [0017]    From another point of view, an exemplary embodiment of the disclosure provides an electronic device that includes a network module and a power saving module. After the network module connects to an AP, the network module executes an AP search operation at a predetermined time interval. The power saving module is coupled to the network module, and the power saving module serves to determine whether the electronic device is in a specific state. When the electronic device is/maintains in the specific state, the network module is disabled from executing the AP search operation. 
         [0018]    According to an exemplary embodiment of the disclosure, wherein the power saving module determines whether the electronic device is in a specific state according to a quality of service between the network module and the AP. 
         [0019]    According to an exemplary embodiment of the disclosure, whenever the network module receives a beacon from the AP, the network module also obtains a received signal strength indication of the AP. When the RSSI is greater than a first threshold value, it is determined that the electronic device is in the specific state. 
         [0020]    According to an exemplary embodiment of the disclosure, whenever the network module receives a beacon from the AP, the network module calculates a signal to noise rate (SNR) of the AP. When the SNR is greater than a second threshold value, it is determined that the electronic device is in the specific state. 
         [0021]    According to an exemplary embodiment of the disclosure, when the electronic device enters an idle mode, the power saving module determines that the electronic device is in the specific state. 
         [0022]    According to an exemplary embodiment of the disclosure, when the electronic device is not in the specific state, the power saving module allows the network module to execute the AP search operation at the predetermined time interval. 
         [0023]    According to the various exemplary embodiments of the disclosure, after the electronic device is connected to an AP through the network module, it is determined that whether to disable the network module from executing an AP search operation according to the quality of service and/or the usage mode of the electronic device. Hence, any expendable AP search operation is reduced to improve power saving. 
         [0024]    In order to the make the aforementioned and other objects, features and advantages of the present invention comprehensible, a preferred embodiment accompanied with figures are described in detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a schematic diagram illustrating the operation after the wireless network interface card is connected to an access point according to the prior art. 
           [0026]      FIG. 2  is a block diagram of an electronic device according to an exemplary embodiment of the disclosure. 
           [0027]      FIG. 3  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. 
           [0028]      FIG. 4  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. 
           [0029]      FIG. 5  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. 
           [0030]      FIG. 6  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. 
           [0031]      FIG. 7  is a schematic diagram showing the operation of the network module after connecting to an access point according to an exemplary embodiment of the disclosure. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0032]      FIG. 2  is a block diagram of an electronic device according to an exemplary embodiment of the disclosure. Referring to  FIG. 2 , the electronic device  200  includes a network module  210  and a power saving module  220  connected to each other. In this exemplary embodiment, the electronic device  200  may be a notebook computer, a cellular phone, a personal digital assistant (PDA), a PDA cellular phone or other types of smartphones. 
         [0033]    The network module  210  includes a wireless network interface card, and the electronic device  200  is connected to an access point (AP) through the network module  210  to access to the wireless network. The wireless network is, for example, a wireless local area network (WLAN). 
         [0034]    The power saving module  220 , for example, is implemented through a software and/or a hardware device. The power saving module  220  is applied to the electronic device  200  for executing a power saving mechanism. Hence, when the electronic device  220  accesses to a network through the network module  210 , unnecessary power loss is reduced. In one exemplary embodiment, when the power saving module is implemented as a software program, this software program is executed directly in/by the operational system of the electronic device  200 . In the exemplary embodiment of the invention, the storage device for storing this software is not limited; the software may be stored, for example, in built-in hard disk of the electronic device  200  or externally connected hard disk, etc. 
         [0035]      FIG. 3  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure.  FIGS. 2 and 3  describe in details the steps of executing the power saving mechanism to reduce the power loss of the electronic device  200 . 
         [0036]    After the power of the electronic device  200  is turned on, as shown in step  310 , the network module  210  connects to an AP in the environment via the execution of an AP search operation (background scan). Thereafter, in step  320 , the power saving module  220  determines whether the electronic device  200  is in a specific state. For example, whether the electronic device  200  is in the specific state is decided by a quality of service between the network module  210  and the AP and/or the usage mode of the electronic device  200 . The quality of service may be for example the connection quality between the network module  210  and the AP. 
         [0037]    If the electronic device  200  is not in the specific state, as in step  330 , the power saving module  220  allows the network module  210  to follow the original wireless network specifications, in which the AP search operation is executed at a predetermined time interval. In contrast, if the electronic device  200  is in the specific state, as in step  340 , the power saving module  220  disables the network module  210  from executing the AP search operation. 
         [0038]    Generally speaking, the action of the AP search operation is a scan request executed by the module driver of the network module  210  in response to a request sent from the system end (electronic device). When the network module  210  and the AP are connected, and the electronic device  200  is in the specific state, the power saving module  220  makes the module driver of the network module  210  drop/ignore the scan request in order to obviate any excess power consumption. However, the original connection between network module  210  and the AP is not affected by the action of the power saving module  220 . In other words, the power saving module disables the AP search operation function of the network module  210 . 
         [0039]    According to the power saving method in the exemplary embodiment, steps  320  to  340  in  FIG. 3  may be continuously repeated. In the mean time, once the electronic device  200  enters and maintains in the specific state, the network module  210  is disabled from executing the AP search operation. In other words, the electronic device  200  may reduce power loss resulted from the execution of the AP search operations. Hence, power saving is achieved. 
         [0040]      FIG. 4  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. In this exemplary embodiment, the power saving module  220  determines whether the electronic device is in a specific state according to a quality of service between the network module  210  and the currently connected AP to decide whether to allow the network module  210  to execute the AP search operation. The quality of service, for example, is represented by a signal strength indication (RSSI) of the AP received by the network module  210 . 
         [0041]    As shown in  FIG. 4 , as in step  410 , the network module  200  executes an AP search operation and eventually connects to an AP in the environment. 
         [0042]    Then, in step  420 , the network module  210  repeatedly determines whether a beacon from the currently connected AP has been received. More specifically, after the network module  210  connects to the AP, the network module  210  sends out an ACK signal for approximately every 0.1 to 1 second (it is to be understood that other time duration may be employed without departing from the invention) to ensure the connection is maintained with the AP. Every time the AP receives the ACK signal from the network module  210 , a beacon is correspondingly feedback to the network module  210 . 
         [0043]    After receiving the beacon from the AP, as shown in step  430 , the network module  210  obtains the RSSI of the AP based on the beacon. Then, in step  440 , the power saving module  220  determines whether the RSSI is greater than a first threshold value. In this exemplary embodiment, the first threshold value is, for example, a value attained by actual measurements through experiments on the operation efficiency of multiple sets of network modules, and further by statistical analysis and experiences, for the value being 15 as an example. It should be noted that the first threshold value may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 
         [0044]    If the RSSI is less than or equal to the first threshold value, the power saving module  220  determines that the electronic device  200  is not in the specific state. More particularly speaking, the electronic device  200  is about to move away from the AP that the network module  210  is currently connected to, and the network module  210  has the opportunity to search for other AP that could be more appropriate/suitable for connection. As in step  450 , the power saving module  220  allows the network module  210  to execute the AP search operation at a predetermined time interval in order to renew the search of AP in the environment. 
         [0045]    If the RSSI is greater than the first threshold value, the power saving module  220  determines that the electronic device  200  is in the specific state. Under this situation, the network module  210  maintains in a stable quality of service, for example, the electronic device  200  remains unmoved, and the distance between the electronic device  200  and the currently connected AP is within the vicinity of the preferred signal coverage. Accordingly, the network module  210  is precluded from wasting time in searching for other APs in the environment. Hence, as in step  460 , the power saving module  220  disables the network module  210  from executing the AP search operation. 
         [0046]    According to the power saving method illustrated in the exemplary embodiment, steps  420  to  460  in  FIG. 4  may be continuously repeated. Whenever the RSSI of the currently connected AP is greater than the first threshold value, it is determined that the electronic device  200  is in the specific state, and the network module  210  is forbidden to execute the AP search operation. Once the electronic device  200  is no longer in the specific state, the network module  210  is allowed to execute the AP search operation at the predetermined time interval. Accordingly, the power loss due to the execution of the AP search operation when the electronic device  200  is in the specific state can be mitigated. Moreover, the electronic device  200  is precluded from not being connected to a new AP because the AP search operation is not being executed by the network module  210  due to the disconnection or a poor quality of service with the originally connected AP when the electron device  200  is being moved or because of other reasons. 
         [0047]      FIG. 5  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. The steps in  FIGS. 4 and 5  are similar, for example, step  510  and  520  are similar to step  410  and  420 ; hence, only the differences between the two embodiments are discussed herein. 
         [0048]    In this exemplary embodiment, the power saving module  220  determines whether the electronic device  200  is in a specific state according to a quality of service between the network module  210  and the currently connected AP. The quality of service is represented by, for example, the signal to noise rate (SNR). 
         [0049]    More specifically, after the network module  210  receives a beacon from the currently connected AP, as in step  530 , the network module  210  calculates the SNR of the AP. For example, the network module  200  may receive the RSSI and the noise value generated by the electronic device  200  itself or from an external interference, and the SNR is the ratio of the RSSI and the noise value. 
         [0050]    Thereafter, as shown in step  540 , the power saving module  220  determines whether the SNR is greater than a second threshold value. The second threshold value is obtainable through actual measurements and statistical methods. The value of the second threshold value should not be limited. 
         [0051]    If the SNR is less than or equal to the second threshold value, the power saving module  220  decides that the electronic device  200  is not in a specific state. In contrast, when the SNR is greater than the second threshold value, the power saving module  220  decides that the electronic device  200  is in the specific state, and the power saving module  220  would apply the appropriate actions similar to those previously described and thus will not reiterated herein. 
         [0052]      FIG. 6  is a flow diagram of steps of an exemplary power saving method according to an embodiment of the disclosure. In this exemplary embodiment, the power saving module  220  determines whether the electronic device  200  is in a specific state according to the usage mode of the electronic device  200 . 
         [0053]    As shown in step  610 , the network module  210  executes the AP search operation to connect to an AP. Then, in step  620 , the power saving module  220  determines whether the electronic device  200  has entered an idle mode. The idle mode is, for example, any mode that ceases the power provision to a part of the electronic device  200 . It should be noted that definition of an idle mode corresponds to the type of electronic device  200  and should not be construed as limited to the embodiments set forth herein. 
         [0054]    If the electronic device has not entered the idle mode, the power saving module  220  determines that the electronic device  200  is not in the specific state. Then, as shown in step  630 , the power saving module  220  allows the network module  210  to execute the AP search operation at a predetermined time interval to renew the search for an appropriate AP in the environment. 
         [0055]    As the electronic device  200  enters the idle mode, the power saving module  220  decides that the electronic device  200  is in the specific state. Hence, as in step  640 , the power saving module  220  disables the network module  210  from executing the AP search operation. 
         [0056]    Since under most situations, the electronic device  200  entering the idle mode indicates that the user is not operating the electronic device  200 . Accordingly, the power saving module  220  may disable the network module  210  to execute the AP search operation to reduce power loss. 
         [0057]    It is worthy to note that, in the above exemplary embodiments, although determining whether the electronic device is in a specific state is based on the value of the RSSI, the value of the SNR, and whether the electronic device  200  has entered the idle mode, the combinations of the above-mentioned factors may be used to determine whether the electronic device  200  is in the specific state in other exemplary embodiments. 
         [0058]    For example, when the electronic device  200  has been determined of entering the idle mode, the power saving module  220  disables the network module  210  from executing the AP search operation. After the electronic device  200  has been determined of resuming to a working mode (such as, receiving an output signal of a mouse, a touch panel or a key board type of output apparatus, or a connection between an external device and the electronic device  200 ), the power saving module  220  decides whether to disable the network module  210  from executing the AP search operation further according to the value of the obtained RSSI and/or the SNR. 
         [0059]      FIG. 7  is a schematic diagram showing the operation of the network module after connecting to an AP according to an exemplary embodiment of the disclosure. In an exemplary embodiment, the network module in the electronic device executes an AP search operation  710  from the time point TP a  to the time point TP b  to connect to an AP. Thereafter, the network module sends out an ACK signal (for example, ACK signal B 1 , B 2 , B 3 , . . . , B n ) for every time period T to the currently connected AP, and the AP would feedback a corresponding beacon (not shown) to the electronic device. As shown in  FIG. 7 , assuming the electron device maintains in the specific state (for example, the RSSI and/or the SNR of the currently connected AP are greater than the corresponding threshold values) during the time point TP b  to the time point TP c , the network module would not execute any AP search operation. Hence, power loss is mitigated and the goal of power saving is accomplished. 
         [0060]    While at the time point TP d , the network module sends an ACK signal B n , to the currently connected AP and obtains a RSSI and/or a SNR according to a beacon correspondingly feedback from the AP. Assuming the power saving module in the electronic device has determined the RSSI and/or the SNR not being higher than the corresponding threshold value, the power saving module immediately decides that the electronic device has departed from the specific state. Hence, the network module would execute the AP search operation  720  when reaching the predetermined time interval (for example, at the time point TP e ) to search for a more appropriate AP for connection. 
         [0061]    According to the electronic device and the power saving method of the exemplary embodiments of the disclosure, when the electronic device is in a specific state, the network module in the electronic device is disabled from executing an AP search operation to reduce the power loss. Consequently, power saving is achieved by not executing any unnecessary AP search operation when the electronic device has a desirable quality of service and/or enters an idle mode. 
         [0062]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.