Multi-level duty cycling

Abstract

A duty cycle scheme for wireless communication employs three or more duty cycle levels. In some aspects, a wireless device may continually scan for signals in an active state associated with a first duty cycle, periodically scan for signals during a periodic state associated with a second duty cycle, and periodically scan for signals during a standby state associated with a third duty cycle. Here, the second duty cycle may be lower than the first duty cycle and the third duty cycle may be lower than the second duty cycle. In some aspects the timing of different states may be correlated. In some aspects each wireless in a system may independently control its duty cycle states.

1 . A method of wireless communication, comprising:
 transmitting on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle;   transmitting on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and   transmitting on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle.   
     
     
         2 . The method of  claim 1 , wherein the first operational state comprises an active state, the second operational state comprises a periodic state, and the third operational state comprises a standby state. 
     
     
         3 . The method of  claim 1 , wherein:
 the transmission during the second operational state comprises transmitting at a time that coincides with the scan timing associated with the second duty cycle;   the transmission during the third operational state comprises transmitting frequently enough so that at least one transmission during the third operational state coincides in time with the scan timing associated with the third duty cycle;   the scan timing associated with the second duty cycle is based on a first time interval;   the scan timing associated with the third duty cycle is based on a second time interval; and   the second time interval is longer than the first time interval.   
     
     
         4 . The method of  claim 3 , wherein the first duty cycle is associated with continuous scanning. 
     
     
         5 . The method of  claim 3 , wherein:
 the first duty cycle is associated with scanning according to a third time interval; and   the third time interval is shorter than the first time interval.   
     
     
         6 . The method of  claim 5 , wherein the transmission during the first operational state comprises transmitting packets, each of which has a preamble that is longer than the third time interval. 
     
     
         7 . The method of  claim 1 , further comprising:
 receiving, at a first wireless node, timing information relating to scan timing of a second wireless node;   defining the transmission times of the second operational state based on the received timing information; and   defining the transmission times of the third operational state based on the received timing information.   
     
     
         8 . The method of  claim 1 , further comprising transitioning between the first, second, and third operational states at a first wireless node based on estimates of operational states of a second wireless node. 
     
     
         9 . The method of  claim 1 , further comprising scanning the channel for a response signal that is responsive to one of the transmissions on the channel. 
     
     
         10 . The method of  claim 1 , further comprising:
 transitioning from the first operational state to the second operational state if a signal is not transmitted during a first timeout period or a signal is transmitted but a response signal is not received during the first timeout period; and   transitioning from the second operational state to the third operational state if a signal is not transmitted during a second timeout period or a signal is transmitted but a response signal is not received during the second timeout period.   
     
     
         11 . The method of  claim 10 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         12 . The method of  claim 1 , further comprising:
 transitioning from the first operational state to the second operational state at a first wireless node if, during a first time period that corresponds to a first defined quantity of successive channel scans of a second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node; and   transitioning from the second operational state to the third operational state at the first wireless node if, during a second time period that corresponds to a second defined quantity of successive channel scans of the second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node.   
     
     
         13 . The method of  claim 12 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         14 . The method of  claim 1 , further comprising:
 transmitting a paging message during the third operational state; and   transitioning from the third operational state to the first operational state if a response to the paging message is received.   
     
     
         15 . The method of  claim 11 , further comprising transitioning from the second operational state to the first operational state if a signal is transmitted and a response signal is received during the second operational state. 
     
     
         16 . The method of  claim 15 , wherein:
 the signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   the response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         17 . The method of  claim 1 , further comprising synchronizing periodic timing associated with the second operational state with periodic timing associated with the third operational state. 
     
     
         18 . The method of  claim 17 , wherein the periodic timing associated with the third operational state and the periodic timing associated with the second operational state are based on a common timing offset. 
     
     
         19 . The method of  claim 1 , further comprising:
 transmitting a paging message; and   receiving a response to the paging message, wherein timing of the receipt of the response provides an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         20 . The method of  claim 1 , further comprising:
 transmitting a paging message; and   receiving a response to the paging message, wherein the response includes an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         21 . The method of  claim 1 , wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type. 
     
     
         22 . An apparatus for wireless communication, comprising:
 a state controller configured to control transitions between a first operational state, a second operational state, and a third operational state; and   a transmitter configured to:
 transmit on a channel at any time during the first operational state, wherein the first operational state is associated with a first duty cycle; 
 transmit on the channel during the second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and 
 transmit on the channel during the third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle. 
   
     
     
         23 . The apparatus of  claim 22 , wherein the first operational state comprises an active state, the second operational state comprises a periodic state, and the third operational state comprises a standby state. 
     
     
         24 . The apparatus of  claim 22 , wherein:
 the transmission during the second operational state comprises transmitting at a time that coincides with the scan timing associated with the second duty cycle;   the transmission during the third operational state comprises transmitting frequently enough so that at least one transmission during the third operational state coincides in time with the scan timing associated with the third duty cycle;   the scan timing associated with the second duty cycle is based on a first time interval;   the scan timing associated with the third duty cycle is based on a second time interval; and   the second time interval is longer than the first time interval.   
     
     
         25 . The apparatus of  claim 24 , wherein the first duty cycle is associated with continuous scanning. 
     
     
         26 . The apparatus of  claim 24 , wherein:
 the first duty cycle is associated with scanning according to a third time interval; and   the third time interval is shorter than the first time interval.   
     
     
         27 . The apparatus of  claim 26 , wherein the transmission during the first operational state comprises transmitting packets, each of which has a preamble that is longer than the third time interval. 
     
     
         28 . The apparatus of  claim 22 , further comprising:
 a receiver configured to receive, at a first wireless node, timing information relating to scan timing of a second wireless node; and   a timing controller configured to define the transmission times of the second operational state based on the received timing information, and further configured to define the transmission times of the third operational state based on the received timing information.   
     
     
         29 . The apparatus of  claim 22 , wherein the state controller is further configured to transition between the first, second, and third operational states at a first wireless node based on estimates of operational states of a second wireless node. 
     
     
         30 . The apparatus of  claim 22 , further comprising a receiver configured to scan the channel for a response signal that is responsive to one of the transmissions on the channel. 
     
     
         31 . The apparatus of  claim 22 , wherein the state controller is further configured to:
 transition from the first operational state to the second operational state if a signal is not transmitted during a first timeout period or a signal is transmitted but a response signal is not received during the first timeout period; and   transition from the second operational state to the third operational state if a signal is not transmitted during a second timeout period or a signal is transmitted but a response signal is not received during the second timeout period.   
     
     
         32 . The apparatus of  claim 31 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         33 . The apparatus of  claim 22 , wherein the state controller is further configured to:
 transition from the first operational state to the second operational state at a first wireless node if, during a first time period that corresponds to a first defined quantity of successive channel scans of a second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node; and   transition from the second operational state to the third operational state at the first wireless node if, during a second time period that corresponds to a second defined quantity of successive channel scans of the second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node.   
     
     
         34 . The apparatus of  claim 33 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         35 . The apparatus of  claim 22 , wherein:
 the transmitter is further configured to transmit a paging message during the third operational state; and   the state controller is further configured to transition from the third operational state to the first operational state if a response to the paging message is received.   
     
     
         36 . The apparatus of  claim 22 , wherein the state controller is further configured to transition from the second operational state to the first operational state if a signal is transmitted and a response signal is received during the second operational state. 
     
     
         37 . The apparatus of  claim 36 , wherein:
 the signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   the response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         38 . The apparatus of  claim 22 , further comprising a timing controller configured to synchronize periodic timing associated with the second operational state with periodic timing associated with the third operational state. 
     
     
         39 . The apparatus of  claim 38 , wherein the periodic timing associated with the third operational state and the periodic timing associated with the second operational state are based on a common timing offset. 
     
     
         40 . The apparatus of  claim 22 , wherein:
 the transmitter is further configured to transmit a paging message; and   the apparatus further comprises a receiver configured to receive a response to the paging message, wherein timing of the receipt of the response provides an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         41 . The apparatus of  claim 22 , wherein:
 the transmitter is further configured to transmit a paging message; and   the apparatus further comprises a receiver configured to receive a response to the paging message, wherein the response includes an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         42 . The apparatus of  claim 22 , wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type. 
     
     
         43 . An apparatus for wireless communication, comprising:
 means for transmitting on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle;   means for transmitting on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and   means for transmitting on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle.   
     
     
         44 . The apparatus of  claim 43 , wherein the first operational state comprises an active state, the second operational state comprises a periodic state, and the third operational state comprises a standby state. 
     
     
         45 . The apparatus of  claim 43 , wherein:
 the transmission during the second operational state comprises transmitting at a time that coincides with the scan timing associated with the second duty cycle;   the transmission during the third operational state comprises transmitting frequently enough so that at least one transmission during the third operational state coincides in time with the scan timing associated with the third duty cycle;   the scan timing associated with the second duty cycle is based on a first time interval;   the scan timing associated with the third duty cycle is based on a second time interval; and   the second time interval is longer than the first time interval.   
     
     
         46 . The apparatus of  claim 45 , wherein the first duty cycle is associated with continuous scanning. 
     
     
         47 . The apparatus of  claim 45 , wherein:
 the first duty cycle is associated with scanning according to a third time interval; and   the third time interval is shorter than the first time interval.   
     
     
         48 . The apparatus of  claim 47 , wherein the transmission during the first operational state comprises transmitting packets, each of which has a preamble that is longer than the third time interval. 
     
     
         49 . The apparatus of  claim 43 , further comprising:
 means for receiving, at a first wireless node, timing information relating to scan timing of a second wireless node;   means for defining the transmission times of the second operational state based on the received timing information; and   means for defining the transmission times of the third operational state based on the received timing information.   
     
     
         50 . The apparatus of  claim 43 , further comprising means for transitioning between the first, second, and third operational states at a first wireless node based on estimates of operational states of a second wireless node. 
     
     
         51 . The apparatus of  claim 43 , further comprising means for scanning the channel for a response signal that is responsive to one of the transmissions on the channel. 
     
     
         52 . The apparatus of  claim 43 , further comprising:
 means for transitioning from the first operational state to the second operational state if a signal is not transmitted during a first timeout period or a signal is transmitted but a response signal is not received during the first timeout period; and   means for transitioning from the second operational state to the third operational state if a signal is not transmitted during a second timeout period or a signal is transmitted but a response signal is not received during the second timeout period.   
     
     
         53 . The apparatus of  claim 52 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         54 . The apparatus of  claim 43 , further comprising:
 means for transitioning from the first operational state to the second operational state at a first wireless node if, during a first time period that corresponds to a first defined quantity of successive channel scans of a second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node; and   means for transitioning from the second operational state to the third operational state at the first wireless node if, during a second time period that corresponds to a second defined quantity of successive channel scans of the second wireless node, a signal is not transmitted or a signal is transmitted but a response signal is not received by the first wireless node.   
     
     
         55 . The apparatus of  claim 54 , wherein:
 each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   each response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         56 . The apparatus of  claim 43 , further comprising:
 means for transmitting a paging message during the third operational state; and   means for transitioning from the third operational state to the first operational state if a response to the paging message is received.   
     
     
         57 . The apparatus of  claim 43 , further comprising means for transitioning from the second operational state to the first operational state if a signal is transmitted and a response signal is received during the second operational state. 
     
     
         58 . The apparatus of  claim 57 , wherein:
 the signal comprises a packet, a data packet, a paging message, a discovery message, or a control message; and   the response signal comprises a response to paging message, a response to discovery message, a response to a control message, or an acknowledgement message.   
     
     
         59 . The apparatus of  claim 43 , further comprising means for synchronizing periodic timing associated with the second operational state with periodic timing associated with the third operational state. 
     
     
         60 . The apparatus of  claim 59 , wherein the periodic timing associated with the third operational state and the periodic timing associated with the second operational state are based on a common timing offset. 
     
     
         61 . The apparatus of  claim 43 , further comprising:
 means for transmitting a paging message; and   means for receiving a response to the paging message, wherein timing of the receipt of the response provides an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         62 . The apparatus of  claim 43 , further comprising:
 means for transmitting a paging message; and   means for receiving a response to the paging message, wherein the response includes an indication of a timing boundary for the second operational state, the third operational state, or the second and third operational states.   
     
     
         63 . The apparatus of  claim 43 , wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type. 
     
     
         64 . A computer-program product for wireless communication, comprising:
 computer-readable medium comprising codes executable to:
 transmit on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle; 
 transmit on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and 
 transmit on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle. 
   
     
     
         65 . A headset for wireless communication, comprising:
 a transmitter configured to:
 transmit on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle; 
 transmit on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and 
 transmit on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle; and 
   a transducer configured to provide an audio output based on data received during at least one of: the first operational state, the second operational state, or the third operational state.   
     
     
         66 . A watch for wireless communication, comprising:
 a transmitter configured to:
 transmit on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle; 
 transmit on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and 
 transmit on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle; and 
   a user interface configured to provide an indication based on data received during at least one of: the first operational state, the second operational state, or the third operational state.   
     
     
         67 . A sensing device for wireless communication, comprising:
 a transmitter configured to:
 transmit on a channel at any time during a first operational state, wherein the first operational state is associated with a first duty cycle; 
 transmit on the channel during a second operational state at times based on scan timing associated with a second duty cycle, wherein the second duty cycle is lower than the first duty cycle; and 
 transmit on the channel during a third operational state at times based on scan timing associated with a third duty cycle, wherein the third duty cycle is lower than the second duty cycle; and 
   a sensor configured to provide data to be transmitted via the transmitter.