Wireless local area network infrastructure mode for reducing power consumption

• US 8,199,686 B1
• Filed: 04/02/2004
• Issued: 06/12/2012
• Est. Priority Date: 03/04/2004
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Donovan, Timothy J.
• Primary Examiner(s): Kincaid, Lester
• Assistant Examiner(s): Jama, Isaak R
• Application Number:
  US10/818,395
• Time in Patent Office: 2,993 Days
• Field of Search: 370/331, 370/338, 370/389, 455/574
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0212 managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: H04W 52/029 reducing the clock frequency of the controller
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A client station that communicates with an access point (AP) in a wireless local area network (LAN) includes a media access control (MAC) device that controls transitions between an active mode and a low power mode. A radio frequency (RF) transceiver communicates with the MAC device. After the MAC device transitions the client station to the active mode, the RF transceiver transmits data to the AP when at least one of the AP finishes transmitting directed data to the RF transceiver and the AP transmits a null data frame to the RF transceiver. The MAC device transitions the client station to the low power mode when the RF transceiver finishes transmitting data to the AP. The AP uses at least one of a random order and a rotating order to access the client station. The client station and the AP are implemented in a console gaming system.

Claims

1. A client station that communicates with an access point (AP) in a wireless local area network (LAN), the client station comprising:

a media access control (MAC) device configured to control transitions between an active mode and a low power mode;

a radio frequency (RF) transceiver configured to communicate with the MAC device,

wherein subsequent to the MAC device transitioning the client station to the active mode, the RF transceiver is configured to transmit data to the AP when at least one of (i) the AP finishes transmitting directed data to the RF transceiver and (ii) the AP transmits a null data frame to the RF transceiver, and

wherein the MAC device is configured to transition the client station to the low power mode when the RF transceiver finishes transmitting data to the AP;

a first voltage regulator configured to regulate supply voltage during the active mode, wherein the first voltage regulator is powered down during the low power mode;

a second voltage regulator configured to dissipate less power than the first voltage regulator, wherein the second voltage regulator is configured to supply voltage during the low power mode,

wherein the MAC device is configured to select (i) the first voltage regulator during the active mode and (ii) the second voltage regulator during the low power mode;

a baseband processor (BBP) configured to (i) perform radio frequency mixing and (ii) communicate with the MAC device and the RF transceiver;

a first phase locked loop (PLL) configured to generate a first clock signal for the BBP during the active mode; and

a crystal oscillator configured to output a timing signal to the first PLL during the active mode,

wherein the RF transceiver is in communication with the BBP and includes a second PLL configured to (i) receive the timing signal from the crystal oscillator during the active mode and (ii) generate a second clock signal for the RF transceiver.

2. The client station of claim 1, wherein the AP uses at least one of (i) a random order and (ii) a rotating order to access the client station.

3. The client station of claim 1, wherein (i) subsequent to the MAC device transitioning the client station to the active mode and (ii) prior to the RF transceiver receiving a timing beacon from the AP, the MAC device is configured to (i) query a host for frames to transmit to the AP and (ii) store the frames.

4. The client station of claim 3, further comprising an internal processor configured to (i) support host functionality and (ii) generate the frames.

5. The client station of claim 1, wherein the MAC device is configured to (i) transition the client station to the active mode prior to a first timing beacon from the AP and (ii) transition the client station to the low power mode prior to a subsequent timing beacon from the AP.

6. The client station of claim 5, wherein the MAC device is configured to update network time based on the first timing beacon.

7. The client station of claim 6, wherein the network time is set equal to a prior beacon time plus a beacon interval minus a fixed delay.

8. A system comprising:

the client station of claim 5; and

the AP, wherein the AP is configured to transmit one of (i) multicast frames and (ii) broadcast frames to the RF transceiver subsequent to transmitting the first timing beacon.

9. The client station of claim 1, wherein the RF transceiver is configured to transmit at least one frame to the AP following a short interframe space (SIFS).

10. A system comprising:

the client station of claim 1; and

the AP, wherein the AP is configured to establish a basic service set (BSS), and wherein the BSS includes (i) a contention free period (CFP) that follows a timing beacon and (ii) a contention base period (CBP) that follows the CFP.

11. The system of claim 10, wherein client stations in a restricted network communicate with the AP during the CFP, and wherein the client stations in the restricted network include the client station of claim 1.

12. The system of claim 11, wherein the AP communicates with at least one wireless device that is external to the restricted network during the CBP.

13. A system comprising:

the client station of claim 1; and

the AP, wherein the AP is configured to transmit a null data frame to the RF transceiver when the AP has zero directed frames to transmit to the RF transceiver.

14. The client station of claim 1, further comprising a first oscillator configured to generate a third clock signal during the low power mode, wherein the first oscillator is configured to dissipate less power than the crystal oscillator.

15. The client station of claim 1, wherein when the MAC device initiates the low power mode, at least one of (i) the first voltage regulator, (ii) the RF transceiver, the first PLL, (iii) the second PLL or (iv) the crystal oscillator is shut down.

16. The client station of claim 14,

wherein the MAC device includes a counter,

wherein when the MAC device initiates the low power mode, the second voltage regulator is configured to power the first oscillator and the counter, and

wherein when the counter reaches a predetermined count, the MAC device is configured to power up at least two of (i) the crystal oscillator, (ii) the first voltage regulator, (iii) the RF transceiver, (iv) the first PLL and (v) the second PLL.

17. The client station of claim 14, further comprising a processor configured to (i) communicate with the crystal oscillator and (ii) calibrate the first oscillator using the timing signal from the crystal oscillator.

18. The client station of claim 1, wherein at least two of (i) the BBP, (ii) the first voltage regulator, (iii) the second voltage regulator, (iv) the RF transceiver, (v) the MAC device, and (vi) the first PLL are implemented by a system on chip (SOC).

19. The client station of claim 1, wherein the client station is otherwise compliant with at least one of IEEE section 802.11, 802.11(a), 802.11(b), or 802.11(g).

20. The client station of claim 1, wherein the wireless LAN is an infrastructure network.

21. The client station of claim 1, wherein the client station is in an infrastructure network.

91. The client station of claim 1, wherein the MAC device is configured to:

transition to the active mode based on a counter value and prior to a beacon interval;

at least one of generate frames or receive the frames from a host;

store the frames in a queue while monitoring reception of a beacon signal; and

update a network time based on the beacon signal.

92. The client station of claim 91, wherein:

the RF transceiver is configured to determine whether the frames are received from the AP; and

the MAC device is configured to process the frames when (i) the frames are from the AP and (ii) the frames are at least one of broadcast frames or multicast frames.

93. The client station of claim 91, wherein:

the RF transceiver is configured to determine whether the frames are received from the AP; and

the MAC device is configured to process the frames when (i) the frames are from the AP, (ii) the frames are not at least one of broadcast frames or multicast frames, and (iii) the frames are directed to the client station.

94. The client station of claim 1, wherein the MAC device is configured to:

process frames received from a host when the frames are received within a short interframe space interval;

determine whether a last frame is received from the AP;

wait the short interframe space interval and transmit a first signal to the AP when the last frame is not received, wherein the first signal transmitted to the AP indicates more data is to be transmitted; and

wait the short interframe space interval and transmit a second signal to the AP when the last frame is not received, wherein the second signal transmitted to the AP indicates no more data is to be transmitted.

95. A system comprising:

the client station of claim 1; and

the AP, wherein the AP is configured to

transmit at least one of broadcast frames or multicast frames to the client station,

transmit the null data frame when the at least one of broadcast frames or multicast frames are directed to the client station, and

transmit a signal indicating whether there is more data to be transmitted when the at least one of broadcast frames or multicast frames are not directed to the client station.

96. The system of claim 95, wherein the AP is configured to:

transmit a beacon signal;

establish a contention free period subsequent to transmitting the beacon signal;

set a value N equal to a number of stations in the wireless LAN;

decrement the value N when there is no more data to be transmitted; and

end the contention free period based on the value N.

97. The client station of claim 1, wherein the MAC device transitions the client station to the low power mode when the RF transceiver finishes transmitting data to the AP without performing a power savings frame exchange with the AP.

22. A wireless local area network (LAN), comprising:

an access point (AP);

a first client station (i) configured to selectively operate in a low power mode and an active mode and (ii) subsequent to transitioning to the active mode, is in communication with the AP; and

a second client station (i) configured to selectively operate in the low power mode and the active mode and (ii) subsequent to transitioning to the active mode, is in communication with the AP,

wherein the AP uses at least one of a random order or a rotating order to access the first client station and the second client station,

wherein when the AP accesses the first client station prior to the second client station, the first client station is configured to transition to the low power mode prior to the AP completing access of the second client station,

wherein the first client station comprises

a first voltage regulator configured to regulate supply voltage during the active mode, wherein the first voltage regulator is powered down during the low power mode;

a second voltage regulator configured to dissipate less power than the first voltage regulator, wherein the second voltage regulator is configured to supply voltage during the low power mode;

a media access control (MAC) device configured to select (i) the first voltage regulator during the active mode and (ii) the second voltage regulator during the low power mode;

a baseband processor (BBP) configured to (i) perform radio frequency mixing and (ii) communicate with the MAC device and a radio frequency (RF) transceiver;

a first phase locked loop (PLL) configured to generate a first clock signal for the BBP during the active mode; and

a crystal oscillator configured to output a timing signal to the first PLL during the active mode,

wherein the RF transceiver is in communication with the BBP and includes a second PLL configured to (i) receive the timing signal from the crystal oscillator during the active mode and (ii) generate a second clock signal for the RF transceiver.

23. The wireless LAN of claim 22, wherein the first client station includes:

a first media access control (MAC) device configured to control transitions between the active mode and the low power mode; and

a first radio frequency (RF) transceiver (i) in communication with the first MAC device and (ii) subsequent to the first MAC device transitioning the first client station to the active mode, configured to transmit data to the AP when at least one of (i) the AP finishes transmitting directed data to the first RF transceiver or (ii) the AP transmits a null data frame to the first RF transceiver,

wherein the first MAC device is configured to transition the first client station to the low power mode when the first RF transceiver finishes transmitting data to the AP.

24. The wireless LAN of claim 23, wherein the second client station includes:

a second MAC device configured to control transitions between the active mode and the low power mode; and

a second RF transceiver (i) in communication with the second MAC device and (ii) subsequent to the second MAC device transitioning the second client station to the active mode, configured to transmit data to the AP when at least one of (i) the AP finishes transmitting directed data to the second RF transceiver and (ii) the AP transmits a null data frame to the second RF transceiver,

wherein the second MAC device is configured to transition the second client station to the low power mode when the second RF transceiver finishes transmitting data to the AP.

25. The wireless LAN of claim 23, wherein the first MAC device is configured to (i) transition the first client station to the active mode prior to a first timing beacon from the AP and (ii) transition the first client station to the low power mode prior to a subsequent timing beacon from the AP.

26. The wireless LAN of claim 25, wherein the first MAC device updates network time based on the first timing beacon.

27. The wireless LAN of claim 26, wherein the network time is set equal to a prior beacon time plus a beacon interval minus a fixed delay.

28. The wireless LAN of claim 23, wherein the first RF transceiver is configured to transmit at least one frame to the AP following a short interframe space (SIFS).

29. The wireless LAN of claim 22, wherein the first client station and the second client station are otherwise compliant with at least one of IEEE section 802.11, 802.11(a), 802.11(b), or 802.11(g).

30. The wireless LAN of claim 22, wherein the wireless LAN is an infrastructure network.

31. The wireless LAN of claim 22, wherein the first client station and the second client station are client stations in an infrastructure network.

32. The wireless LAN of claim 22, wherein (i) subsequent to the first client station and the second client station transitioning to the active mode and (ii) prior to the first client station and the second client station receiving a timing beacon from the AP, at least one of the first client station and the second client station storing frames to transmit to the AP.

33. The wireless LAN of claim 25, wherein the AP is configured to transmit one of multicast frames and broadcast frames to the first client station and the second client station immediately subsequent to transmitting the first timing beacon.

34. The wireless LAN of claim 22, wherein the AP is configured to establish a basic service set (BSS), and wherein the BSS includes (i) a contention free period (CFP) that follows a timing beacon and (ii) a contention base period (CBP) that follows the CFP.

35. The wireless LAN of claim 34, wherein only client stations in a restricted network are in communication with the AP during the CFP, and wherein the client stations in the restricted network include the first client station and the second client station.

36. The wireless LAN of claim 35, wherein the AP is in communication with at least one wireless device, wherein the at least one wireless device is external to the restricted network during the CBP.

37. The wireless LAN of claim 23, wherein the AP is configured to transmit the null data frame to the first RF transceiver when the AP does not have directed frames to transmit to the first RF transceiver.

98. The wireless LAN of claim 22, wherein the AP is configured to:

transmit a plurality of beacon signals to a plurality of client stations including the first client station and the second client station;

determine a client station access sequence subsequent to each of a plurality of beacon intervals, wherein the client station access sequence indicates an order in which the plurality of client stations communicate with the AP; and

equalize power consumption between the plurality of client stations including varying the client station access sequence by at least one of randomizing or rotating the order subsequent to transmitting each of the beacon signals.

38. A client station configured to communicate with an access point (AP) in a wireless local area network (LAN), the client station comprising:

media access controlling means for controlling transitions between an active mode and a low power mode;

radio frequency transceiving means for (i) transmitting and receiving radio frequency signals and (ii) for communicating with the media access controlling means,

wherein subsequent to the media access controlling means transitioning the client station to the active mode, the radio frequency transceiving means transmits data to the AP when at least one of (i) the AP finishes transmitting directed data to the radio frequency transceiving means and (ii) the AP transmits a null data frame to the radio frequency transceiving means, and

wherein the media access controlling means transitions the client station to the low power mode when the radio frequency transceiving means finishes transmitting data to the AP;

first voltage regulating means for regulating supply voltage during the active mode, wherein the first voltage regulating means is powered down during the low power mode;

second voltage regulating means (i) for dissipating less power than the first voltage regulating means and (ii) for regulating supply voltage during the low power mode,

wherein the media access controlling means selects (i) the first voltage regulating means during the active mode and (ii) the second voltage regulating means during the low power mode;

baseband processing means for performing radio frequency mixing and for communicating with the media access controlling means and the radio frequency transceiving means;

first means for generating a first clock signal for the baseband processing means during the active mode; and

first means for outputting a timing signal to the first means during the active mode,

wherein the radio frequency transceiving means communicates with the baseband processing means and includes second means (i) for receiving the timing signal during the active mode and (ii) for generating a second clock signal.

39. The client station of claim 38, wherein the AP uses at least one of a random order or a rotating order to access the client station.

40. The client station of claim 38, wherein (i) subsequent to the media access controlling means transitioning the client station to the active mode and (ii) prior to the radio frequency transceiving means receiving a timing beacon from the AP, the media access controlling means (i) queries a host for frames to transmit to the AP and (ii) stores the frames.

41. The client station of claim 40, further comprising internal processing means for supporting host functionality and for generating the frames.

42. The client station of claim 38, wherein the media access controlling means (i) transitions the client station to the active mode prior to a first timing beacon from the AP and (ii) transitions the client station to the low power mode prior to a subsequent timing beacon from the AP.

43. The client station of claim 42, wherein the media access controlling means updates network time based on the first timing beacon.

44. The client station of claim 43, wherein the network time is set equal to a prior beacon time plus a beacon interval minus a fixed delay.

45. A system comprising:

the client station of claim 42; and

the AP, wherein the AP transmits one of multicast frames and broadcast frames to the radio frequency transceiving means subsequent to transmitting the first timing beacon.

46. The client station of claim 38, wherein the radio frequency transceiving means transmits at least one frame to the AP following a short interframe space (SIFS).

47. A system comprising:

the client station of claim 38; and

the AP, wherein the AP establishes a basic service set (BSS) that includes (i) a contention free period (CFP) that follows a timing beacon and (ii) a contention base period (CBP) that follows the CFP.

48. The system of claim 47, wherein only client stations in a restricted network communicate with the AP during the CFP, and wherein the client stations in the restricted network include the client station of claim 38.

49. The system of claim 48, wherein the AP communicates with at least one wireless device that is external to the restricted network during the CBP.

50. A system comprising:

the client station of claim 38; and

the AP, wherein the AP transmits a null data frame to the radio frequency transceiving means when the AP has zero directed frames to transmit to the radio frequency transceiving means.

51. The client station of claim 38, further comprising second oscillating means for generating a third clock signal during the low power mode, wherein the second oscillating means dissipates less power than the first oscillating means.

52. The client station of claim 38, wherein when the media access controlling means initiates the low power mode, at least one of (i) the first voltage regulating means, (ii) the radio frequency transceiving means, (iii) the first means, (iv) the second means or (v) the first oscillating means is shut down.

53. The client station of claim 51, wherein the media access controlling means includes counting means for counting,

wherein when the media access controlling means initiates the low power mode, the second voltage regulating means powers (i) the second oscillating means and (ii) the counting means, and

wherein when the counting means reaches a predetermined count, the media access controlling means powers up at least two of (i) the first oscillating means, (ii) the first voltage regulating means, (iii) the radio frequency transceiving means, (iv) the first means and (v) the second means.

54. The client station of claim 51, further comprising processing means (i) for communicating with the first oscillating means and (ii) for calibrating the second oscillating means using the timing signal from the first oscillating means.

55. The client station of claim 38, wherein at least two of (i) the baseband processing means, (ii) the first voltage regulating means, (iii) the second voltage regulating means, (iv) the radio frequency transceiving means, (v) the media access controlling means, and (vi) the first means are implemented by a system on chip (SOC).

56. The client station of claim 38, wherein the client station is otherwise compliant with at least one of IEEE section 802.11, 802.11(a), 802.11(b), or 802.11(g).

57. The client station of claim 38, wherein the wireless LAN is an infrastructure network.

58. The client station of claim 38, wherein the client station is in an infrastructure network.

59. A method for operating a client station configured to communicate with an access point (AP) in a wireless local area network (LAN), the method comprising:

controlling transitions of the client station between an active mode and a low power mode;

transitioning the client station to the active mode;

transmitting data to the AP when at least one of (i) the AP finishes transmitting directed data to the client station or (ii) the AP transmits a null data frame to the client station;

transitioning the client station to the low power mode when the client station finishes transmitting data to the AP;

regulating a supply voltage during the active mode via a first voltage regulator, wherein the first voltage regulator is powered down during the low power mode;

dissipating, via a second voltage regulator, less power than the first voltage regulator, wherein the second voltage regulator is configured to supply voltage during the low power mode;

selecting, via a media access controller (MAC) device, (i) the first voltage regulator during the active mode and (ii) the second voltage regulator during the low power mode;

performing radio frequency (RF) mixing;

communicating with the MAC device and a RF transceiver via a baseband processor (BBP);

generating a first clock signal for the BBP during the active mode via a first phase locked loop (PLL);

outputting a timing signal to the first PLL during the active mode via a crystal oscillator;

receiving the timing signal from the crystal oscillator during the active mode via a second PLL; and

generating a second clock signal for the RF transceiver.

60. The method of claim 59, wherein the AP uses at least one of (i) a random order or (ii) a rotating order to access the client station.

61. The method of claim 59, further comprising:

querying a host for frames to transmit to the AP (i) subsequent to transitioning the client station to the active mode and (ii) prior to receiving a timing beacon from the AP; and

storing the frames.

62. The method of claim 61, wherein an internal processor functions as the host and generates the frames.

63. The method of claim 59, further comprising:

transitioning the client station to the active mode prior to a first timing beacon from the AP; and

transitioning the client station to the low power mode prior to a subsequent timing beacon from the AP.

64. The method of claim 63, further comprising updating network time based on the first timing beacon.

65. The method of claim 64, further comprising setting the network time equal to a prior beacon time plus a beacon interval minus a fixed delay.

66. The method of claim 63, wherein the AP transmits one of multicast frames and broadcast frames to the client station immediately subsequent to transmitting the first timing beacon.

67. The method of claim 59, further comprising transmitting at least one frame to the AP following a short interframe space (SIFS).

68. The method of claim 59, wherein the AP establishes a basic service set (BSS) that includes (i) a contention free period (CFP) that follows a timing beacon and (ii) a contention base period (CBP) that follows the CFP.

69. The method of claim 59, wherein the AP transmits a null data frame to the client station when the AP has zero directed frames to transmit to the client station.

70. The method of claim 59, further comprising implementing the client station and the AP in a console gaming system.

71. The method of claim 70, further comprising:

implementing the client station in an input device of the console gaming system; and

implementing the AP in a console of the console gaming system.

72. The method of claim 59, wherein the client station is otherwise compliant with at least one of IEEE section 802.11, 802.11(a), 802.11(b), or 802.11(g).

73. The method of claim 59, wherein the wireless LAN is an infrastructure network.

74. The method of claim 59, wherein the client station is in an infrastructure network.

75. A method for operating a wireless local area network (LAN), the method comprising:

selectively operating a first client station and a second client station in a low power mode and an active mode;

establishing communications between the first and second client stations and an access point (AP) of the wireless LAN subsequent to transitioning the first and second client stations, respectively, to the active mode;

using at least one of a random order or a rotating order to access the first client station and the second client station;

accessing the first client station prior to the second client station;

transitioning the first client station to the low power mode prior to the AP completing access of the second client station; and

via the first client station

regulating a supply voltage during the active mode via a first voltage regulator, wherein the first voltage regulator is powered down during the low power mode;

dissipating, via a second voltage regulator, less power than the first voltage regulator, wherein the second voltage regulator is configured to supply voltage during the low power mode;

selecting, via a media access controller (MAC) device, (i) the first voltage regulator during the active mode and (ii) the second voltage regulator during the low power mode;

performing radio frequency mixing;

communicating with the MAC device and a radio frequency (RF) transceiver via a baseband processor (BBP);

generating a first clock signal for the BBP during the active mode via a first phase locked loop (PLL);

outputting a timing signal to the first PLL during the active mode via a crystal oscillator;

receiving the timing signal from the crystal oscillator during the active mode via a second PLL; and

generating a second clock signal for the RF transceiver.

76. The method of claim 75, further comprising:

transitioning the first client station to the active mode;

transmitting data from the first client station to the AP when at least one of (i) the AP finishes transmitting directed data to the first client station or (ii) the AP transmits a null data frame to the first client station; and

transitioning the first client station to the low power mode when the first client station finishes transmitting data to the AP.

77. The method of claim 75, further comprising:

transitioning the second client station to the active mode;

transmitting data to the AP when at least one of (i) the AP finishes transmitting directed data to the second client station or (ii) the AP transmits a null data frame to the second client station; and

transitioning the second client station to the low power mode when the second client station finishes transmitting data to the AP.

78. The method of claim 76, further comprising:

transitioning the first client station to the active mode prior to a first timing beacon from the AP; and

transitioning the first client station to the low power mode prior to a subsequent timing beacon from the AP.

79. The method of claim 78, further comprising updating network time based on the first timing beacon.

80. The method of claim 79, further comprising setting the network time equal to a prior beacon time plus a beacon interval minus a fixed delay.

81. The method of claim 76, further comprising transmitting at least one frame to the AP following a short interframe space (SIFS).

82. The method of claim 75, wherein the first client station and the second client station are otherwise compliant with at least one of IEEE section 802.11, 802.11(a), 802.11(b), or 802.11(g).

83. The method of claim 75, wherein the wireless LAN is an infrastructure network.

84. The method of claim 75, wherein the first client station and the second client station are in an infrastructure network.

85. The method of claim 75, further comprising:

transitioning the first client station and the second client station to the active mode; and

storing frames to transmit to the AP in at least one of (i) the first client station or (ii) the second client station prior to the first client station and the second client station receiving a timing beacon from the AP.

86. The method of claim 78, further comprising:

transmitting the first timing beacon; and

immediately transmitting one of multicast frames and broadcast frames from the AP to the first client station and the second client station.

87. The method of claim 75, further comprising establishing a basic service set (BSS) that includes (i) a contention free period (CFP) that follows a timing beacon and (ii) a contention base period (CBP) that follows the CFP.

88. The method of claim 87, wherein client stations in a restricted network communicate with the AP during the CFP, and wherein the client stations in the restricted network include the first client station and the second client station.

89. The method of claim 88, further comprising communicating with at least one wireless device that is external to the restricted network during the CBP.

90. The method of claim 76, further comprising transmitting the null data frame to the first client station when the AP does not have directed frames to transmit to the first client station.