Wireless local area network apparatus

Abstract

A wireless local area network apparatus includes a transmitter and a receiver in which operation of the receiver is accurately synchronized with periodic signals from the transmitter. The periodic signals contain timing data indicating the state of a timer in the transmitter at the time the signal containing that data was transmitted and this timing data is retrieved from the signal when received by the receiver and loaded in a timer for controlling operation of the receiver.

1 . A receiver for a wireless local area network (WLAN), the receiver comprising: 
 a radio modem adapted to receive, from a transmitter of the WLAN, a transmission signal containing a time stamp value;    a first register adapted to receive the transmission signal from which the time stamp value is retrieved;    a timer adapted to initiate a count sequence based on the time stamp value and generate a timer control signal based on the count sequence; and    a controller adapted to control operations of the receiver based on the timer control signal from the timer.    
   
   
       2 . The invention of  claim 1 , wherein the controller is adapted to control timing of energizing of the radio modem based on the timer control signal to enable the radio modem to receive a subsequent transmission signal from the transmitter.  
   
   
       3 . The invention of  claim 2 , wherein the energizing of the radio modem corresponds to a transition from a doze state to an awake state.  
   
   
       4 . The invention of  claim 1 , wherein initiating the count sequence based on the time stamp value synchronizes the timer with a corresponding timer in the transmitter.  
   
   
       5 . The invention of  claim 4 , wherein the transmitter timer is a free-running timer.  
   
   
       6 . The invention of  claim 1 , wherein the timer comprises a modulo n counter.  
   
   
       7 . The invention of  claim 1 , wherein the transmission signal is a TIM (Traffic Indication Message) packet.  
   
   
       8 . The invention of  claim 1 , wherein the timer control signal is generated at the completion of the count sequence.  
   
   
       9 . The invention of  claim 1 , wherein the time stamp value corresponds to a transmitter timer value after transmission from the transmitter of a header of the transmission signal has started.  
   
   
       10 . The invention of  claim 1 , wherein the time stamp value represents a value within a count sequence of a timer in the transmitter.  
   
   
       11 . The invention of  claim 10 , wherein the time stamp value represents the value within the count sequence of the timer in the transmitter at a time of transmission of the transmission signal from the transmitter.  
   
   
       12 . A method for a receiver in a wireless local area network (WLAN), the method comprising: 
 (a) receiving, from a transmitter of the WLAN, a transmission signal containing a time stamp value;    (b) retrieving the time stamp value from the transmission signal;    (c) initiating a count sequence based on the time stamp value;    (d) generating a timer control signal based on the count sequence; and    (e) controlling operations of the receiver based on the timer control signal.    
   
   
       13 . The invention of  claim 12 , wherein step (e) comprises controlling timing of energizing of a radio modem in the receiver based on the timer control signal to enable the radio modem to receive a subsequent transmission signal from the transmitter.  
   
   
       14 . The invention of  claim 13 , wherein the energizing of the radio modem corresponds to a transition from a doze state to an awake state.  
   
   
       15 . The invention of  claim 12 , wherein initiating the count sequence based on the time stamp value synchronizes the receiver with a timer in the transmitter.  
   
   
       16 . The invention of  claim 12 , wherein the timer control signal is generated at the completion of the count sequence.  
   
   
       17 . The invention of  claim 12 , wherein the time stamp value corresponds to a transmitter timer value after transmission from the transmitter of a header of the transmission signal has started.  
   
   
       18 . The invention of  claim 12 , wherein the time stamp value represents a value within a count sequence of a timer in the transmitter.  
   
   
       19 . The invention of  claim 18 , wherein the time stamp value represents the value within the count sequence of the timer in the transmitter at a time of transmission of the transmission signal from the transmitter.