Abstract:
Between a user equipment and a base station in a wireless network system, a plurality of data links are simultaneously established for communication. The amounts of power for respectively maintaining the data links are adjusted according to the transmission quality of each corresponding data link, so that the data link with better transmission quality may receive more resource for improving the overall data throughput of the data links.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is related to a power management method for use in a wireless network system, and more particularly, to a power management method for improving data throughput of a wireless network system. 
         [0003]    2. Description of the Prior Art 
         [0004]    Wireless network has been more and more widespread with rapid development in technology. Communication technologies commonly adopted in current wireless network systems include CDMA (code division multiple access), TD-SCDMA (time division synchronous code division multiple access), WiMAX (worldwide interoperability for microwave access), UMB (ultra mobile broadband), LTE (long term evolution), or LTE-A (Long Term Evolution-Advanced). 
         [0005]    A wireless network system normally performs power management by adjusting the output power of a user equipment. For example, open loop power control is a power management scheme in which the user equipment is configured to detect and adjust its output power to a specified value suitable for transmission. Closed loop power control is a power management scheme in which a base station is configured to detect and control the output power of the user equipment. 
         [0006]    Since the user equipment at client side normally communicates with a single server base station/cell at the same time in most wireless network systems, current standards only specify the power control scheme for single-channel communication. However, multi-channel communication may be performed in LTE-A systems using at least one carrier component when communicating with at least one cell/access point, such as coordinated multipoint transmission/reception (CoMP) or multiple input multiple output (MIMO), relay deployment, etc. In such wireless network system providing multiple data links, the carrier aggregation, cell coverage, cell inter-distance and interference control of each data link may vary. Therefore, current power control scheme specified for single data link may not be suitable for such multi-channel communication. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a power management method for use in a wireless network system. The power management method includes providing a first power for establishing a first data link between a user equipment and a base station; providing a second power for establishing a second data link between the user equipment and the base station; determining a transmission quality of the first data link and a transmission quality of the second data link; and adjusting the first power and the second power so that the first power is larger than the second power if it is determined that the transmission quality of the first data link is better than the transmission quality of the second data link. 
         [0008]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a diagram illustrating a wireless network system according to the present invention. 
           [0010]      FIG. 2  is a flowchart illustrating the operation of the wireless network system according to the present invention. 
           [0011]      FIG. 3  is a diagram illustrating a power management method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  is a diagram illustrating a wireless network system  100  according to the present invention. The wireless network system  100  includes a user equipment UE and a base station BS, between which multiple data links DL 1 -DLn may be established for intercommunication. P 1 -Pn represent the power required for maintaining the data links DL 1 -DLn, respectively. 
         [0013]      FIG. 2  is a flowchart illustrating the operation of the wireless network system  100  according to the present invention. The flowchart in  FIG. 2  includes the following steps: 
         [0014]    Step  210 : provide the power P 1 -Pn for establishing the data links DL 1 -DLn between the user equipment UE and the base station BS; execute step  220 . 
         [0015]    Step  220 : determine the transmission quality of the data links DL 1 -DLn; execute step  230 . 
         [0016]    Step  230 : adjust the power P 1 -Pn according to the transmission quality of the corresponding data link so as to maintain a better data link with higher power; execute step  220 . 
         [0017]    When executing step  210  in uplink mode, data is transmitted from the user equipment UE, which provides the power P 1 -Pn for maintaining the data links DL 1 -DLn, to the base station BS. When executing step  210  in downlink mode, data is transmitted from the base station BS to the user equipment UE which provides the power P 1 -Pn for maintaining the data links DL 1 -DLn. 
         [0018]    In step  220 , the user equipment UE may determine the transmission quality of the data links DL 1 -DLn. In an embodiment of the present invention, the user equipment UE is configured to measure the data throughput of each data link directly. If the data throughput of the data link DL 1  is larger than that of the data link D 2 , it can be determined that the data links DL 1  has better transmission quality than the data link DL 2  In another embodiment of the present invention, the user equipment UE is configured to measure parameters of each data link, such as BLER (block error rate), BER (bit error rate), QoS (quality of service) or TBS (transport block size). If the parameter of the data link DL 1  is better than that of the data link D 2 , it can be determined that the data links DL 1  has better transmission quality than the data link DL 2 . 
         [0019]    As depicted in  FIG. 3 , the user equipment UE may adjust corresponding power P 1 -Pn according to the transmission quality of the data links DL 1 -DLn when executing step  230  in uplink mode. For example, when it is determined in step  220  that the relationship of data link quality is DL 1 &gt;DL 2 &gt; . . . &gt;DLn, the user equipment UE may adjust it output power in step  230  so that P 1 &gt;P 2 &gt; . . . &gt;Pn. Therefore, more resources may be allocated to maintain the better data link. 
         [0020]    In downlink mode, the user equipment UE is configured to send a TPC (transport power control) signal according to the signal-to-interference ratio (SIR) of each data link, thereby informing the base station BS of the required power for maintaining each data link. If an estimated signal-to-interference ratio SIR ESTIMATE  of a specific data link is larger a target signal-to-interference ratio SIR TARGET , the user equipment UE may instruct the base station BS to lower the power for maintaining the specific data link (power down). If the estimated signal-to-interference ratio SIR ESTIMATE  of the specific data link is smaller than the target signal-to-interference ratio SIR TARGET , the user equipment UE may instruct the base station BS to increase the power for maintaining the specific data link (power up). Therefore, when executing step  230  in downlink mode, the user equipment UE may adjust corresponding target signal-to-interference ratios SIR TARGET1 ˜SIR TARGETn  according to the transmission quality of the data links DL 1 -DLn. For example, when it is determined in step  220  that the relationship of data link quality is DL 1 &gt;DL 2 &gt; . . . &gt;DLn, the user equipment UE may adjust each target signal-to-interference ratio so that SIR TARGET1 &gt;SIR TARGET2 &gt; . . . &gt;SIR TARGETn . Therefore, more resources may be allocated to maintain the better data link. 
         [0021]    In wireless network systems, a slight downgrade in transmission quality may require resending data which largely lowers the overall data throughput. On the other hand, data throughput of wireless data link largely increases with slight improvement in transmission quality. In the present invention, the power for maintaining each data link is adjusted according to the transmission quality of the corresponding data link. Therefore, more resources may be allocated to maintain the better data link, thereby improving the overall data throughput of all data links. 
         [0022]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.