Wireless local area network apparatus

• US 7,289,578 B2
• Filed: 01/13/2006
• Issued: 10/30/2007
• Est. Priority Date: 03/06/1993
• Status: Expired due to Fees

• Current Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: van Bokhorst, Hendrik, van Driest, Hans, Diepstraten, Wilhelmus J. M.
• Primary Examiner(s): Bocure; Tesfaldet
• Application Number:
  US11/331,919
• Publication Number:
  US 20060121861A1
• Time in Patent Office: 655 Days
• Field of Search: 375/354, 375/316, 375362-366, 375/340, 455/334, 455/343, 370503-514
• US Class Current: 375/316
• CPC Class Codes: H04L 27/04 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 7/04 Speed or phase control by synchronisation signals H04L7/0075 takes precedence
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 56/009 Closed loop measurements
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/022 Selective call receivers
• CPC Class Codes: Y02D 30/70 in wireless communication networks

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.

Claims

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, wherein the time stamp value takes into account delay at the transmitter;

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 the controller is adapted to control frequency hopping by the radio modem based on the timer control signal to adjust frequency tuning of the radio modem for receipt of a subsequent transmission signal from the transmitter.

5. The invention of claim 4, 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 the subsequent transmission signal from the transmitter.

6. The invention of claim 5, wherein the controller is adapted to implement multiple frequency hops while the radio modem is de-energized prior to receipt of the subsequent transmission signal.

7. The invention of claim 1, wherein:

the count sequence is based on a timer interval value; and

the timer is adapted to initiate the count sequence based on the time stamp value such that the duration of the count sequence corresponds to a difference between the timer interval value and the time stamp value.

8. The invention of claim 7, wherein the timer is adapted to increment a counter from the time stamp value to the timer interval value during the count sequence.

9. The invention of claim 7, wherein:

the timer interval value is explicitly encoded into the transmission signal; and

the receiver is adapted to retrieve the timer interval value from the transmission signal and apply the timer interval value in the timer.

10. The invention of claim 9, wherein the explicit encoding of the timer interval value into the transmission signal enables the receiver to implement different count sequences having different timer interval values.

11. The invention of claim 1, wherein the time stamp value corresponds to a delay in the transmission of the transmission signal from the transmitter, the delay resulting from a collision avoidance protocol implemented by the transmitter.

12. The invention of claim 1, wherein the receiver further comprises a second register connected between the first register and the timer and adapted to store the time stamp value until receipt of the transmission signal is complete.

13. The invention of claim 12, wherein the second register enables the receiver to receive transmissions signals having different sizes.

14. The invention of claim 12, wherein the receiver further comprises a checker adapted to verify whether the receiver should continue to process the transmission signal, such that the time stamp value is provided to the timer from the second register after the checker verifies that the receiver should continue to process the transmission signal.

15. The invention of claim 14, wherein:

a check value is explicitly coded into the transmission signal;

the receiver is adapted to retrieve the check value from the transmission signal; and

the checker is adapted to perform its verification processing based on the retrieved check value.

16. The invention of claim 1, wherein the receiver further comprises an adder adapted to adjust the time stamp value by a specified offset value prior to application of the adjusted time stamp value to the timer.

17. The invention of claim 16, wherein the receiver is adapted to apply the specified offset value to compensate for propagation delay of the receiver.

18. The invention of claim 17, wherein the receiver is adapted to apply the specified offset value to compensate for propagation delay of the transmitter and the receiver.

19. 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.

20. The invention of claim 19, wherein the transmitter timer is a free-running timer.

21. The invention of claim 1, wherein the timer comprises a modulo n counter.

22. The invention of claim 1, wherein the transmission signal is a TIM (Traffic Indication Message) packet.

23. The invention of claim 1, wherein the receiver further comprises:

a second register connected between the first register and the timer and adapted to store the time stamp value until receipt of the transmission signal is complete, wherein the second register enables the receiver to receive transmissions signals having different sizes;

a checker adapted to verify whether the receiver should continue to process the transmission signal, such that the time stamp value is provided to the timer from the second register after the checker verifies that the receiver should continue to process the transmission signal, wherein;

a check value is explicitly coded into the transmission signal;

the receiver is adapted to retrieve the check value from the transmission signal; and

the checker is adapted to perform its verification processing based on the retrieved check value; and

an adder adapted to adjust the time stamp value by a specified offset value prior to application of the adjusted time stamp value to the timer, wherein the receiver is adapted to apply the specified offset value to compensate for propagation delay between the transmitter and the receiver, wherein;

the transmission signal is a TIM packet;

the time stamp value corresponds to a delay in the transmission of the transmission signal from the transmitter, the delay resulting from a collision avoidance protocol implemented by the transmitter;

initiating the count sequence based on the time stamp value synchronizes the timer with a corresponding free-running timer in the transmitter;

the count sequence is based on a timer interval value explicitly encoded into the transmission signal;

the explicit encoding of the timer interval value into the transmission signal enables the receiver to implement different count sequences having different timer interval values;

the receiver is adapted to retrieve the timer interval value from the transmission signal and apply the timer interval value in the timer; and

the timer comprises a modulo n counter adapted to count by incrementing from the adjusted time stamp value to the timer interval value during the count sequence such that the duration of the count sequence corresponds to a difference between the timer interval value and the time stamp value.

24. The invention of claim 23, 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, wherein the energizing of the radio modem corresponds to a transition from a doze state to an awake state; and

the controller is adapted to control frequency hopping by the radio modem based on the timer control signal to adjust frequency tuning of the radio modem for receipt of the subsequent transmission signal from the transmitter, wherein the controller is adapted to implement multiple frequency hops while the radio modem is de-energized prior to receipt of the subsequent transmission signal.

25. The invention of claim 1, wherein the timer control signal is generated at the completion of the count sequence.

26. The invention of claim 1, wherein the time stamp value takes into account modem delay at the transmitter.

27. 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.

28. The invention of claim 1, wherein the time stamp value accounts for delays at the transmitter due to a busy signal on a medium access protocol.

29. The invention of claim 1, wherein the time stamp value accounts for a delay between a start of a transmitter process to transmit the transmission signal and an actual time of transmitting the transmission signal from the transmitter.

30. The invention of claim 1, wherein the time stamp value represents a value within a count sequence of a timer in the transmitter.

31. The invention of claim 30, 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.

32. The invention of claim 30, wherein the time stamp value is loaded into a timestamp field of the transmission signal with a value that, with regard to delays in a modem of the transmitter, is an estimate of the value within the count sequence of the timer in the transmitter at which the transmission signal will be transmitted from the transmitter.

33. The invention of claim 1, wherein step (c) comprises:

(1) adjusting the time stamp value; and

(2) initiating the count sequence beginning at the adjusted time stamp value.

34. The invention of claim 33, wherein step (c)(1) comprises adjusting the time stamp value to compensate for propagation delay at the receiver.

35. The invention of claim 33, wherein step (c)(1) comprises adjusting the time stamp value to allow for time taken to process the transmission signal at the receiver.

40. The invention of claim 25, wherein the timer control signal is generated at the completion of the count sequence.

36. 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, wherein the time stamp value takes into account delay at the transmitter;

(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.

37. The invention of claim 36, wherein step (c) comprise 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.

38. The invention of claim 37, wherein the energizing of the radio modem corresponds to a transition from a dozen state to an awake state.

39. The invention of claim 36, wherein steps (e) comprises controlling frequency hopping by a radio modem in the receiver based on the timer control signal to adjust frequency tuning of the radio modem for receipt of a subsequent transmission signal from the transmitter.

41. The invention of claim 36, wherein:

the count sequence is based on a timer interval value; and

step (c) comprises initiating the count sequence based on the time stamp value such that the duration of the count sequence corresponds to a difference between the timer interval value and the time stamp value.

42. The invention of claim 41, wherein:

the timer interval value is explicitly encoded into the transmission signal; and

step (b) further comprises retrieving the timer interval value from the transmission signal and applying the timer interval value in step (c).

43. The invention of claim 36, wherein the time stamp value corresponds to a delay in the transmission of the transmission signal from the transmitter, the delay resulting from a collision avoidance protocol implemented by the transmitter.

44. The invention of claim 36, wherein step (b) further comprises storing the time stamp value until receipt of the transmission signal is complete.

45. The invention of claim 44, wherein the storing of the time stamp value enables the receiver to receive transmissions signals having different sizes.

46. The invention of claim 44, wherein step (b) further comprises verifying whether the receiver should continue to process the transmission signal, such that the time stamp value is provided to step (c) after verifying that the receiver should continue to process the transmission signal.

47. The invention of claim 36, wherein step (c) further comprises adjusting the time stamp value by a specified offset value prior to application of the adjusted time stamp value to the count sequence.

48. The invention of claim 47, wherein the receiver applies the specified offset value to compensate for propagation delay of the receiver.

49. The invention of claim 48, wherein the receiver applies the specified offset value to compensate for propagation delay of the transmitter and the receiver.

50. The invention of claim 36, wherein initiating the count sequence based on the time stamp value synchronizes the receiver with a timer in the transmitter.

51. The invention of claim 36, wherein the timer control signal is generated at the completion of the count sequence.

52. The invention of claim 36, wherein the time stamp value takes into account delay at the transmitter.

53. The invention of claim 36, 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.

54. The invention of claim 36, wherein the time stamp value accounts for delays at the transmitter due to a busy signal on a medium access protocol.

55. The invention of claim 36, wherein the time stamp value accounts for a delay between a start of a transmitter process to transmit the transmission signal and an actual time of transmitting the transmission signal from the transmitter.

56. The invention of claim 36, wherein the time stamp value represents a value within a count sequence of a timer in the transmitter.

57. The invention of claim 56, 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.

58. The invention of claim 56, wherein the time stamp value is loaded into a timestamp field of the transmission signal with a value that, with regard to delays in a modem of the transmitter, is an estimate of the value within the count sequence of the timer in the transmitter at which the transmission signal will be transmitted from the transmitter.

59. The invention of claim 36, wherein step (c) comprises:

(1) adjusting the time stamp value; and

(2) initiating the count sequence beginning at the adjusted time stamp value.

60. The invention of claim 59, wherein step (c)(1) comprises adjusting the time stamp value to compensate for propagation delay at the receiver.

61. The invention of claim 59, wherein step (c)(1) comprises adjusting the time stamp value to allow for time taken to process the transmission signal at the receiver.

62. 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, wherein the controller is adapted to control frequency hopping by the radio modem based on the timer control signal to adjust frequency tuning of the radio modem for receipt of a subsequent transmission signal from the transmitter.

63. The invention of claim 62, 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 the subsequent transmission signal from the transmitter.

64. The invention of claim 63, wherein the controller is adapted to implement multiple frequency hops while the radio modem is de-energized prior to receipt of the subsequent transmission signal.

65. 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, wherein;

the count sequence is based on a timer interval value; and

the timer is adapted to initiate the count sequence based on the time stamp value such that the duration of the count sequence corresponds to a difference between the timer interval value and the time stamp value.

66. The invention of claim 65, wherein the timer is adapted to increment a counter from the time stamp value to the timer interval value during the count sequence.

67. The invention of claim 65, wherein:

the timer interval value is explicitly encoded into the transmission signal; and

the receiver is adapted to retrieve the timer interval value from the transmission signal and apply the timer interval value in the timer.

68. The invention of claim 67, wherein the explicit encoding of the timer interval value into the transmission signal enables the receiver to implement different count sequences having different timer interval values.

69. 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, wherein the time stamp value corresponds to a delay in the transmission of the transmission signal from the transmitter, the delay resulting from a collision avoidance protocol implemented by the transmitter.

70. 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, wherein the receiver further comprises a second register connected between the first register and the timer and adapted to store the time stamp value until receipt of the transmission signal is complete.

71. The invention of claim 70, wherein the second register enables the receiver to receive transmissions signals having different sizes.

72. The invention of claim 70, wherein the receiver further comprises a checker adapted to verify whether the receiver should continue to process the transmission signal, such that the time stamp value is provided to the timer from the second register after the checker verifies that the receiver should continue to process the transmission signal.

73. The invention of claim 72, wherein:

a check value is explicitly coded into the transmission signal;

the receiver is adapted to retrieve the check value from the transmission signal; and

the checker is adapted to perform its verification processing based on the retrieved check value.

74. 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;

a controller adapted to control operations of the receiver based on the timer control signal from the timer; and

an adder adapted to adjust the time stamp value by a specified offset value prior to application of the adjusted time stamp value to the timer.

75. The invention of claim 74, wherein the receiver is adapted to apply the specified offset value to compensate for propagation delay of the receiver.

76. The invention of claim 75, wherein the receiver is adapted to apply the specified offset value to compensate for propagation delay of the transmitter and the receiver.

77. 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, wherein the time stamp value accounts for delays at the transmitter due to a busy signal on a medium access protocol.

78. 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, wherein the time stamp value accounts for a delay between a start of a transmitter process to transmit the transmission signal and an actual time of transmitting the transmission signal from the transmitter.

79. 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, wherein;

the time stamp value represents a value within a count sequence of a timer in the transmitter; and

the time stamp value is loaded into a timestamp field of the transmission signal with a value that, with regard to delays in a modem of the transmitter, is an estimate of the value within the count sequence of the timer in the transmitter at which the transmission signal will be transmitted from the transmitter.

80. 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, wherein the timer is adapted to;

(1) adjust the time stamp value; and

(2) initiate the count sequence beginning at the adjusted time stamp value.

81. The invention of claim 80, wherein the timer is adapted to adjust the time stamp value to compensate for propagation delay at the receiver.

82. The invention of claim 80, wherein the timer is adapted to adjust the time stamp value to allow for time taken to process the transmission signal at the receiver.

83. 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, wherein step (e) comprises controlling frequency hopping by a radio modem in the receiver based on the timer control signal to adjust frequency tuning of the radio modem for receipt of a subsequent transmission signal from the transmitter.

84. The invention of claim 83, wherein step (e) further comprises controlling timing of energizing of the radio modem based on the timer control signal to enable the radio modem to receive the subsequent transmission signal from the transmitter.

85. 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, wherein;

the count sequence is based on a timer interval value; and

step (c) comprises initiating the count sequence based on the time stamp value such that the duration of the count sequence corresponds to a difference between the timer interval value and the time stamp value.

86. The invention of claim 85, wherein:

the timer interval value is explicitly encoded into the transmission signal; and

step (b) further comprises retrieving the timer interval value from the transmission signal and applying the timer interval value in step (c).

87. 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, wherein the time stamp value corresponds to a delay in the transmission of the transmission signal from the transmitter, the delay resulting from a collision avoidance protocol implemented by the transmitter.

88. 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, wherein step (b) further comprises storing the time stamp value until receipt of the transmission signal is complete.

89. The invention of claim 88, wherein the storing of the time stamp value enables the receiver to receive transmissions signals having different sizes.

90. The invention of claim 88, wherein step (b) further comprises verifying whether the receiver should continue to process the transmission signal, such that the time stamp value is provided to step (c) after verifying that the receiver should continue to process the transmission signal.

91. 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, wherein step (c) further comprises adjusting the time stamp value by a specified offset value prior to application of the adjusted time stamp value to the count sequence.

92. The invention of claim 91, wherein the receiver applies the specified offset value to compensate for propagation delay of the receiver.

93. The invention of claim 92, wherein the receiver applies the specified offset value to compensate for propagation delay of the transmitter and the receiver.

94. 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, wherein the time stamp value accounts for delays at the transmitter due to a busy signal on a medium access protocol.

95. 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, wherein the time stamp value accounts for a delay between a start of a transmitter process to transmit the transmission signal and an actual time of transmitting the transmission signal from the transmitter.

96. 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, wherein;

the time stamp value represents a value within a count sequence of a timer in the transmitter; and

the time stamp value is loaded into a timestamp field of the transmission signal with a value that, with regard to delays in a modem of the transmitter, is an estimate of the value within the count sequence of the timer in the transmitter at which the transmission signal will be transmitted from the transmitter.

97. 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, wherein step (c) comprises;

(1) adjusting the time stamp value; and

(2) initiating the count sequence beginning at the adjusted time stamp value.

98. The invention of claim 97, wherein step (c)(1) comprises adjusting the time stamp value to compensate for propagation delay at the receiver.

99. The invention of claim 97, wherein step (c)(1) comprises adjusting the time stamp value to allow for time taken to process the transmission signal at the receiver.