Low power module for a station of a wireless communication system and related method

Abstract

The invention relates to a low power module, and in particular, to a low power module applied in a station of a wireless communication system. A low power module includes a first MAC module, a second MAC module, a low power switch register, a control register unit, a slow clock generator, and a multiplexer (MUX) The first and second MAC module transmits and receives packets in a normal operational mode and a power save mode, respectively. The low power switch register switches a current mode to another mode. The control register unit controls the RF/BB module and the clock generator under the control of the low power switch register. The slow clock generator generates a slow operational clock for the second MAC module in the power save mode. The MUX chooses the normal operational or the slow operational clock periodically as a clock of the second MAC module according to the control register unit.

1 . A user station applied in a wireless communication system, said wireless communication system comprises an access point (AP) and a plurality of stations, the plurality of stations and the AP send packets to communicate with each other, the user station comprising: 
 a host module for controlling operation of the user station;    a low power module coupled to the host module for transmitting/receiving packets with low power consumption of the user station;    a RF/BB module coupled to the host module and the low power module for processing various signals from the packets; and    a clock generator coupled to the host module, the low power module, and the RF/BB module for providing a normal operational clock to the station.    
   
   
       2 . The user station according to  claim 1 , wherein the host module is a CPU or a micro-processor.  
   
   
       3 . The user station according to  claim 1 , wherein the clock generator is a phase lock loon (PLL) or an oscillator.  
   
   
       4 . The user station according to  claim 1 , wherein the wireless communication system is an 802.11 communication system and the station is an 802.11 station.  
   
   
       5 . The user station according to  claim 4 , wherein the low power module further comprises: 
 a first MAC module for transmitting and receiving packets in a normal operational mode and sleeping in a power save mode;    a second MAC module for transmitting and receiving packets in the power save mode and sleeping in the normal operational mode;    a low power switch register coupled to the first and second MAC modules for switching the user station between the power save mode and the normal operational mode;    a control register unit coupled to the low power switch register for controlling the RF/BB module and the clock generator to sleep to save power consumption if the low power switch register controls the user station in the power save mode;    a slow clock generator for generating a slow operational clock for the second MAC module in the power save mode; and    a multiplexer (MUX) coupled to the control register unit, the normal operational clock and the slow clock generator for choosing the normal operational or the slow operational clock periodically as a clock of the second MAC module if the control register unit controls the RF/BB module and the clock generator to sleep to save power consumption;    wherein the second MAC module sends a wake up event to the first MAC module to wake up the first MAC module and control the low power switch register to switch to the normal operational mode if the second MAC module received a specific packet or a specific beacon in the power save mode.    
   
   
       6 . The user station according to  claim 5 , wherein if the first MAC module is a MAC module with no CPU, the RF/BB module will be controlled by the host module directly in the normal operational mode.  
   
   
       7 . The user station according to  claim 5 , wherein if the first MAC module comprises an embedded CPU, the RF/BB module will be controlled by the first MAC module directly in the normal operational mode.  
   
   
       8 . The user station according to  claim 5 , wherein the second MAC module further comprises: 
 a low power unit for sending/receiving packets in a listen phase of the power save mode and does nothing to save power in a deep sleep phase of the power save mode; and    a TSF timer for counting a predetermined wakeup time for the low power unit to switch the listen phase and the deep sleep phase automatically in the power save mode.    
   
   
       9 . The user station according to  claim 5 , wherein the low power switch register can be reset by a driver of the host module to switch current operation mode dynamically at any time.  
   
   
       10 . The user station according to  claim 8 , wherein the MUX chooses the normal operational clock as a clock of the second MAC module in the listen phase and chooses the slow operational clock as the clock of the second MAC module in the deep sleep phase according to the predetermined wakeup time.  
   
   
       11 . A low power module applied in a station, said station applied in a wireless communication system, said wireless communication system comprises an access point (AP) and a plurality of stations, the plurality of stations and the AP send packets to communicate with each other, the low power module comprising: 
 a first MAC module for transmitting and receiving packets in a normal operational mode and sleeping in a power save mode;    a second MAC module for transmitting and receiving packets in the power save mode and sleeping in the normal operational mode;    a low power switch register coupled to the first and second MAC modules for switching the user station between the power save mode and the normal operational mode;    a control register unit coupled to the low power switch register for controlling the RF/BB module and the clock generator to sleep to save power consumption if the low power switch register controls the user station in the power save mode;    a slow clock generator for generating a slow operational clock for the second MAC module in the power save mode; and    a multiplexer (MUX) coupled to the control register unit, the normal operational clock and the slow clock generator for choosing the normal operational or the slow operational clock periodically as a clock of the second MAC module if the control register unit controls the RF/BB module and the clock generator to sleep to save power consumption;    wherein the second MAC module sends a wake up event to the first MAC module to wake up the first MAC module and control the low power switch register to switch to the normal operational mode if the second MAC module received a specific packet or a specific beacon in the power save mode.    
   
   
       12 . The low power module according to  claim 11 , wherein if the first MAC module is a MAC module with no CPU, the RF/BB module will be controlled by the host module directly in the normal operational mode.  
   
   
       13 . The low power module according to  claim 11 , wherein if the first MAC module comprises an embedded CPU, the RF/BB module will be controlled by the first MAC module directly in the normal operational mode.  
   
   
       14 . The low power module according to  claim 11 , wherein the second MAC module further comprises: 
 a low power unit for sending/receiving packets in a listen phase of the power save mode and does nothing to save power in a deep sleep phase of the power save mode; and    a TSF timer for counting a predetermined wakeup time for the low power unit to switch the listen phase and the deep sleep phase automatically in the power save mode.    
   
   
       15 . The low power module according to  claim 11 , wherein the low power switch register can be reset by a driver of the host module to switch the current mode dynamically at any time.  
   
   
       16 . The low power module according to  claim 14 , wherein the MUX chooses the normal operational clock as the clock of the second MAC module in the listen phase and chooses the slow operational clock as the clock of the second MAC module in the deep sleep phase according to the predetermined wakeup time.  
   
   
       17 . A method of controlling a user station applied in a wireless communication system, said wireless communication system comprises an access point (AP) and a plurality of stations, the plurality of stations and the AP send packets to communicate with each other, the user station comprises a low power unit, a low power switch register, and a host module, said low power unit is utilized for saving power consumption, said low power switch register is utilized for switching the user station control, and said host module is utilized for controlling the entire operation of the station, comprising: 
 entering a power save mode wherein the power save mode comprises a listen phase and a deep sleep phase;    switching periodically between the listen phase and the deep sleep phase wherein the low power unit waits for a wanted beacon or a wanted packet in the listen phase and does nothing in the deep sleep phase;    synchronizing the low power unit with the AP automatically for best power saving when receiving a beacon;    transmitting a NULL packet and waiting for acknowledgement while losing beacon packet several times for basic connection; and    returning to a normal operational mode.    
   
   
       18 . The station controlling method according to  claim 17 , wherein the step of entering the power save mode further comprising: 
 informing the AP that the user station will change to the power save mode from the normal operational mode;    setting the user station by a plurality of instructions wherein the plurality of instructions comprises information of a waited packet type for waking up a host module, a timer for beacon, a PLL turning on/off timing, and a RF/BB control sequences; and    switching the user station control from the host module to the low power unit and entering to the power save mode.    
   
   
       19 . The station controlling method according to  claim 17 , wherein the step of returning to the normal operational mode further comprising: 
 asserting a wake up event to wake up the host module if a wanted beacon is received; and    resetting the low power switch register and switching the user station control from the low power unit to the host module and returning to the normal operational mode.    
   
   
       20 . The station controlling method according to  claim 18 , wherein the step of switching the user station control further comprises setting a low power switch register to switch the user station control.  
   
   
       21 . The station controlling method according to  claim 19 , wherein a pattern of the wanted packet can be programmed by the host module.  
   
   
       22 . The station controlling method according to  claim 17 , wherein the wireless communication specification between the AP and the user station is IEEE 802.11.  
   
   
       23 . The station controlling method according to  claim 17 , wherein the step of switching periodically between the listen phase and the deep sleep phase further comprises: 
 transmitting and receiving packets in the listen phase and doing nothing to save power in the deep sleep phase;    transmitting a NULL packet and waiting for acknowledgement while losing beacon packet several times for basic connection; and    counting a predetermined wakeup time to switch the listen phase and the deep sleep phase automatically.    
   
   
       24 . The station controlling method according to  claim 23 , wherein the low power switch register can be reset in the power save mode to directly leave the power save mode and return to the normal operational mode.  
   
   
       25 . The station controlling method according to  claim 23 , wherein a normal operational clock is chosen as an operational clock of the low power unit in the listen phase and a slow operational clock is chosen as the operational clock of the low power unit in the deep sleep phase.