MULTI-LEVEL DUTY CYCLING

• US 20090270030A1
• Filed: 05/09/2008
• Published: 10/29/2009
• Est. Priority Date: 04/23/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Julian, David Jonathan, Jia, Zhanfeng, Lee, Chong U
• Granted Patent: US 8,473,013 B2
• Time in Patent Office: Days
• US Class Current: 455/39
• CPC Class Codes: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/0274 by switching on or off the equipment or parts thereof
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: Y02D 30/70 in wireless communication networks

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.

Claims

1. A method of wireless communication, comprising:

scanning a channel according to a first duty cycle during a first operational state;

scanning the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scanning the channel according to a third duty cycle during a third operational state, 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 channel scanning according to the second duty cycle comprises periodically scanning at times based on a first time interval;

the channel scanning according to the third duty cycle comprises periodically scanning at times 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 channel scanning according to the first duty cycle comprises continuously scanning the channel.

5. The method of claim 3, wherein:

the channel scanning according to the first duty cycle comprises periodically scanning at times based on a third time interval; and

the third time interval is shorter than the first time interval.

6. The method of claim 5, wherein the third time interval corresponds to a scanning rate that is high enough to capture a preamble of an asynchronous packet.

7. The method of claim 5, wherein a duration of any one of the first time interval, the second time interval, or the third time interval is based on at least one of:

a size of a packet preamble, clock drift, or a probability of not detecting a packet.

8. The method of claim 1, further comprising:

transitioning from the first operational state to the second operational state if a signal is not received during a first timeout period; and

transitioning from the second operational state to the third operational state if a signal is not received during a second timeout period.

9. The method of claim 8, wherein each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message.

10. The method of claim 1, further comprising:

transitioning from the first operational state to the second operational state if a signal is not received during a first defined quantity of successive channel scans; and

transitioning from the second operational state to the third operational state if a signal is not received during a second defined quantity of successive channel scans.

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.

12. The method of claim 1, further comprising:

transitioning from the third operational state to the first operational state if a signal is received; and

transitioning from the second operational state to the first operational state if a signal is received.

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.

14. The method of claim 1, further comprising correlating periodic timing of the scanning during the third operational state with periodic timing of the scanning during the second operational state.

15. The method of claim 14, wherein the periodic timing of the scanning during the third operational state and the periodic timing of the scanning during the second operational state are based on a common timing offset.

16. The method of claim 1, further comprising transmitting a response signal if a signal is received during any of the channel scanning, wherein the response signal comprises an acknowledgement message or a response to a paging message.

17. The method of claim 1, further comprising:

receiving a paging message; and

transmitting a response to the paging message, wherein timing of the transmission of the response provides an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

18. The method of claim 1, further comprising:

receiving a paging message; and

transmitting a response to the paging message, wherein the response includes an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

19. The method of claim 1, further comprising:

receiving paging messages from a plurality of nodes within a defined period of time; and

transmitting a single response to the paging messages.

20. The method of claim 19, wherein the transmission of the single response comprises broadcasting the single response over a channel that is common to the plurality of nodes.

21. The method of claim 19, wherein a length of a preamble of the single response is based on relative scanning period times associated with the plurality of nodes.

22. 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.

23. 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 receiver configured to;

scan a channel according to a first duty cycle during the first operational state;

scan the channel according to a second duty cycle during the second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scan the channel according to a third duty cycle during the third operational state, wherein the third duty cycle is lower than the second duty cycle.

24. The apparatus of claim 23, 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.

25. The apparatus of claim 23, wherein:

the channel scanning according to the second duty cycle comprises periodically scanning at times based on a first time interval;

the channel scanning according to the third duty cycle comprises periodically scanning at times based on a second time interval; and

the second time interval is longer than the first time interval.

26. The apparatus of claim 25, wherein the channel scanning according to the first duty cycle comprises continuously scanning the channel.

27. The apparatus of claim 25, wherein:

the channel scanning according to the first duty cycle comprises periodically scanning at times based on a third time interval; and

the third time interval is shorter than the first time interval.

28. The apparatus of claim 27, wherein the third time interval corresponds to a scanning rate that is high enough to capture a preamble of an asynchronous packet.

29. The apparatus of claim 27, wherein a duration of any one of the first time interval, the second time interval, or the third time interval is based on at least one of:

a size of a packet preamble, clock drift, or a probability of not detecting a packet.

30. The apparatus of claim 23, wherein the state controller is further configured to:

transition from the first operational state to the second operational state if a signal is not received during a first timeout period; and

transition from the second operational state to the third operational state if a signal is not received during a second timeout period.

31. The apparatus of claim 30, wherein each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message.

32. The apparatus of claim 23, wherein the state controller is further configured to:

transition from the first operational state to the second operational state if a signal is not received during a first defined quantity of successive channel scans; and

transition from the second operational state to the third operational state if a signal is not received during a second defined quantity of successive channel scans.

33. The apparatus of claim 32, wherein each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message.

34. The apparatus of claim 23, wherein the state controller is further configured to:

transition from the third operational state to the first operational state if a signal is received; and

transition from the second operational state to the first operational state if a signal is received.

35. The apparatus of claim 34, wherein each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message.

36. The apparatus of claim 23, further comprising a timing controller configured to correlate periodic timing of the scanning during the third operational state with periodic timing of the scanning during the second operational state.

37. The apparatus of claim 36, wherein the periodic timing of the scanning during the third operational state and the periodic timing of the scanning during the second operational state are based on a common timing offset.

38. The apparatus of claim 23, further comprising a transmitter configured to transmit a response signal if a signal is received by the receiver during any of the channel scanning, wherein the response signal comprises an acknowledgement message or a response to a paging message.

39. The apparatus of claim 23, wherein:

the receiver is further configured to receive a paging message; and

the apparatus further comprises a transmitter configured to transmit a response to the paging message, wherein timing of the transmission of the response provides an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

40. The apparatus of claim 23, wherein:

the receiver is further configured to receive a paging message; and

the apparatus further comprises a transmitter configured to transmit a response to the paging message, wherein the response includes an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

41. The apparatus of claim 23, wherein:

the receiver is further configured to receive paging messages from a plurality of nodes within a defined period of time; and

the apparatus further comprises a transmitter configured to transmit a single response to the paging messages.

42. The apparatus of claim 41, wherein the transmission of the single response comprises broadcasting the single response over a channel that is common to the plurality of nodes.

43. The apparatus of claim 41, wherein a length of a preamble of the single response is based on relative scanning period times associated with the plurality of nodes.

44. The apparatus of claim 23, wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type.

45. An apparatus for wireless communication, comprising:

means for scanning a channel according to a first duty cycle during a first operational state;

means for scanning the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

means for scanning the channel according to a third duty cycle during a third operational state, wherein the third duty cycle is lower than the second duty cycle.

46. The apparatus of claim 45, 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.

47. The apparatus of claim 45, wherein:

the channel scanning according to the second duty cycle comprises periodically scanning at times based on a first time interval;

the channel scanning according to the third duty cycle comprises periodically scanning at times based on a second time interval; and

the second time interval is longer than the first time interval.

48. The apparatus of claim 47, wherein the channel scanning according to the first duty cycle comprises continuously scanning the channel.

49. The apparatus of claim 47, wherein:

the channel scanning according to the first duty cycle comprises periodically scanning at times based on a third time interval; and

the third time interval is shorter than the first time interval.

50. The apparatus of claim 49, wherein the third time interval corresponds to a scanning rate that is high enough to capture a preamble of an asynchronous packet.

51. The apparatus of claim 49, wherein a duration of any one of the first time interval, the second time interval, or the third time interval is based on at least one of:

a size of a packet preamble, clock drift, or a probability of not detecting a packet.

52. The apparatus of claim 45, further comprising:

means for transitioning from the first operational state to the second operational state if a signal is not received during a first timeout period; and

means for transitioning from the second operational state to the third operational state if a signal is not received during a 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.

54. The apparatus of claim 45, further comprising:

means for transitioning from the first operational state to the second operational state if a signal is not received during a first defined quantity of successive channel scans; and

means for transitioning from the second operational state to the third operational state if a signal is not received during a second defined quantity of successive channel scans.

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.

56. The apparatus of claim 45, further comprising:

means for transitioning from the third operational state to the first operational state if a signal is received; and

means for transitioning from the second operational state to the first operational state if a signal is received.

57. The apparatus of claim 56, wherein each signal comprises a packet, a data packet, a paging message, a discovery message, or a control message.

58. The apparatus of claim 45, further comprising means for correlating periodic timing of the scanning during the third operational state with periodic timing of the scanning during the second operational state.

59. The apparatus of claim 58, wherein the periodic timing of the scanning during the third operational state and the periodic timing of the scanning during the second operational state are based on a common timing offset.

60. The apparatus of claim 45, further comprising means for transmitting a response signal if a signal is received during any of the channel scanning, wherein the response signal comprises an acknowledgement message or a response to a paging message.

61. The apparatus of claim 45, further comprising:

means for receiving a paging message; and

means for transmitting a response to the paging message, wherein timing of the transmission of the response provides an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

62. The apparatus of claim 45, further comprising:

means for receiving a paging message; and

means for transmitting a response to the paging message, wherein the response includes an indication of timing of the scanning during the second operational state, the third operational state, or the second and third operational states.

63. The apparatus of claim 45, further comprising:

means for receiving paging messages from a plurality of nodes within a defined period of time; and

means for transmitting a single response to the paging messages.

64. The apparatus of claim 63, wherein the transmission of the single response comprises broadcasting the single response over a channel that is common to the plurality of nodes.

65. The apparatus of claim 63, wherein a length of a preamble of the single response is based on relative scanning period times associated with the plurality of nodes.

66. The apparatus of claim 45, wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type.

67. A computer-program product for wireless communication, comprising:

computer-readable medium comprising codes executable to;

scan a channel according to a first duty cycle during a first operational state;

scan the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scan the channel according to a third duty cycle during a third operational state, wherein the third duty cycle is lower than the second duty cycle.

68. A headset for wireless communication, comprising:

a receiver configured to;

scan a channel according to a first duty cycle during a first operational state;

scan the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scan the channel according to a third duty cycle during a third operational state, 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 via the receiver.

69. A watch for wireless communication, comprising:

a receiver configured to;

scan a channel according to a first duty cycle during a first operational state;

scan the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scan the channel according to a third duty cycle during a third operational state, 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 via the receiver.

70. A sensing device for wireless communication, comprising:

a receiver configured to;

scan a channel according to a first duty cycle during a first operational state;

scan the channel according to a second duty cycle during a second operational state, wherein the second duty cycle is lower than the first duty cycle; and

scan the channel according to a third duty cycle during a third operational state, wherein the third duty cycle is lower than the second duty cycle; and

a sensor configured to provide data to be transmitted during at least one of;

the first operational state, the second operational state, or the third operational state.

71. 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.

72. The method of claim 71, 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.

73. The method of claim 71, 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.

74. The method of claim 73, wherein the first duty cycle is associated with continuous scanning.

75. The method of claim 73, 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.

76. The method of claim 75, 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.

77. The method of claim 71, 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.

78. The method of claim 71, 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.

79. The method of claim 71, further comprising scanning the channel for a response signal that is responsive to one of the transmissions on the channel.

80. The method of claim 71, 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.

81. The method of claim 80, 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.

82. The method of claim 71, 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.

83. The method of claim 82, 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.

84. The method of claim 71, 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.

85. The method of claim 71, 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.

86. The method of claim 85, 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.

87. The method of claim 71, further comprising synchronizing periodic timing associated with the second operational state with periodic timing associated with the third operational state.

88. The method of claim 87, 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.

89. The method of claim 71, 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.

90. The method of claim 71, 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.

91. The method of claim 71, wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type.

92. 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.

93. The apparatus of claim 92, 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.

94. The apparatus of claim 92, 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.

95. The apparatus of claim 94, wherein the first duty cycle is associated with continuous scanning.

96. The apparatus of claim 94, 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.

97. The apparatus of claim 96, 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.

98. The apparatus of claim 92, 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.

99. The apparatus of claim 92, 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.

100. The apparatus of claim 92, further comprising a receiver configured to scan the channel for a response signal that is responsive to one of the transmissions on the channel.

101. The apparatus of claim 92, 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.

102. The apparatus of claim 101, 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.

103. The apparatus of claim 92, 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.

104. The apparatus of claim 103, 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.

105. The apparatus of claim 92, 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.

106. The apparatus of claim 92, 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.

107. The apparatus of claim 106, 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.

108. The apparatus of claim 92, 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.

109. The apparatus of claim 108, 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.

110. The apparatus of claim 92, 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.

111. The apparatus of claim 92, 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.

112. The apparatus of claim 92, wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type.

113. 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.

114. The apparatus of claim 113, 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.

115. The apparatus of claim 113, 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.

116. The apparatus of claim 115, wherein the first duty cycle is associated with continuous scanning.

117. The apparatus of claim 115, 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.

118. The apparatus of claim 117, 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.

119. The apparatus of claim 113, 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.

120. The apparatus of claim 113, 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.

121. The apparatus of claim 113, further comprising means for scanning the channel for a response signal that is responsive to one of the transmissions on the channel.

122. The apparatus of claim 113, 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.

123. The apparatus of claim 122, 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.

124. The apparatus of claim 113, 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.

125. The apparatus of claim 124, 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.

126. The apparatus of claim 113, 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.

127. The apparatus of claim 113, 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.

128. The apparatus of claim 127, 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.

129. The apparatus of claim 113, further comprising means for synchronizing periodic timing associated with the second operational state with periodic timing associated with the third operational state.

130. The apparatus of claim 129, 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.

131. The apparatus of claim 113, 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.

132. The apparatus of claim 113, 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.

133. The apparatus of claim 113, wherein at least one of the first duty cycle, the second duty cycle, or the third duty cycle is based on a node type.

134. 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.

135. 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.

136. 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.

137. 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.