METHOD AND APPARATUS FOR SAVING POWER BY USING SIGNAL FIELD OF PREAMBLE

• US 20120182980A1
• Filed: 07/13/2011
• Published: 07/19/2012
• Est. Priority Date: 07/16/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Abraham, Santosh Paul, Sampath, Hemanth, Vermani, Sameer
• Granted Patent: US 9,094,175 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 1/0044 specially adapted for power saving
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Certain aspects of the present disclosure relate to a technique for power saving at mobile stations in Very High Throughput (VHT) systems using signal field bits of a preamble with a limited transmission overhead. The present disclosure proposes a method of indicating to a destination through a preamble cyclic redundancy check (CRC) checksum that the destination may be the intended destination of a transmission packet. The present disclosure also proposes a method of indicating to a destination through a preamble CRC that the destination may not be the intended destination of a transmission packet. In this case, decoding of the received packet can be terminated in order to save power at a receiving device.

Claims

1. An apparatus for communications, comprising:

a first circuit configured to define a first signal field by altering a second signal field, wherein the alteration is based on at least one identifier;

a second circuit configured to generate a checksum for the first signal field; and

a transmitter configured to transmit a packet comprising the second signal field with the checksum generated for the first signal field therein.

2. The apparatus of claim 1, wherein locations of bits of the second signal field modified during the alteration are determined based on the at least one identifier.

3. The apparatus of claim 1, wherein the first circuit is also configured to:

insert the at least one identifier into the second signal field to define the first signal field.

4. The apparatus of claim 1, wherein the first circuit is also configured to:

perform XOR operation between at least one bit of the second signal field and at least one bit of the at least one identifier.

5. The apparatus of claim 1, wherein the first circuit is also configured to:

divide the second signal field into a plurality of sub-fields; and

alter bits in one or more of the sub-fields.

6. The apparatus of claim 5, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

7. The apparatus of claim 6, further comprising:

a third circuit configured to provide the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field to an apparatus associated with the at least one identifier.

8. The apparatus of claim 1, wherein the first circuit is also configured to:

scramble bits of the second signal field based on the at least one identifier to define the first signal field.

9. The apparatus of claim 1, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

10. The apparatus of claim 9, further comprising:

a third circuit configured to provide information related to the alteration to an apparatus associated with the destination ID.

11. The apparatus of claim 9, further comprising:

a third circuit configured to indicate, to an apparatus associated with the destination ID, a procedure used for the alteration.

12. The apparatus of claim 1, wherein the at least one identifier comprises a group ID, and the apparatus further comprising:

a third circuit configured to indicate, to an apparatus associated with the group ID, a procedure used for the alteration.

13. The apparatus of claim 1, wherein:

the checksum is placed in a header of the packet being transmitted in accordance with IEEE 802.11 family of wireless communications standards, and

the header comprises a service field of the packet.

14. The apparatus of claim 1, wherein the second signal field comprises at least one of a Very High Throughput Signal field type A or a Very High Throughput Signal field type B of the packet transmitted in accordance with IEEE 802.11 family of wireless communications standards.

15. The apparatus of claim 1, wherein the at least one identifier comprises at least one of:

an association identification (AID) of a source apparatus transmitting the packet, an AID of a destination apparatus, or a Basic Service Set Identification (BSSID) of an access point serving at least one of the source apparatus or the destination apparatus.

16. A method for communications, comprising:

defining a first signal field by altering a second signal field, wherein the alteration is based on at least one identifier;

generating a checksum for the first signal field; and

transmitting a packet comprising the second signal field with the checksum generated for the first signal field therein.

17. The method of claim 16, wherein locations of bits of the second signal field modified during the alteration are determined based on the at least one identifier.

18. The method of claim 16, wherein defining the first signal field comprises:

inserting the at least one identifier into the second signal field.

19. The method of claim 16, wherein defining the first signal field comprises:

performing XOR operation between at least one bit of the second signal field and at least one bit of the at least one identifier.

20. The method of claim 16, wherein defining the first signal field comprises:

dividing the second signal field into a plurality of sub-fields; and

altering bits in one or more of the sub-fields.

21. The method of claim 20, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

22. The method of claim 21, further comprising:

providing the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field to an apparatus associated with the at least one identifier.

23. The method of claim 16, wherein defining the first signal field comprises:

scrambling bits of the second signal field based on the at least one identifier.

24. The method of claim 16, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

25. The method of claim 24, further comprising:

providing information related to the alteration to an apparatus associated with the destination ID.

26. The method of claim 24, further comprising:

indicating, to an apparatus associated with the destination ID, a procedure used for the alteration.

27. The method of claim 16, wherein the at least one identifier comprises a group ID, and the method further comprising:

indicating, to an apparatus associated with the group ID, a procedure used for the alteration.

28. The method of claim 16, wherein:

the checksum is placed in a header of the packet being transmitted in accordance with IEEE 802.11 family of wireless communications standards, and

the header comprises a service field of the packet.

29. The method of claim 16, wherein the second signal field comprises at least one of a Very High Throughput Signal field type A or a Very High Throughput Signal field type B of the packet transmitted in accordance with IEEE 802.11 family of wireless communications standards.

30. The method of claim 16, wherein the at least one identifier comprises at least one of:

an association identification (AID) of a source apparatus transmitting the packet, an AID of a destination apparatus, or a Basic Service Set Identification (BSSID) of an access point serving at least one of the source apparatus or the destination apparatus.

31. An apparatus for communications, comprising:

means for defining a first signal field by altering a second signal field, wherein the alteration is based on at least one identifier;

means for generating a checksum for the first signal field; and

means for transmitting a packet comprising the second signal field with the checksum generated for the first signal field therein.

32. The apparatus of claim 31, wherein locations of bits of the second signal field modified during the alteration are determined based on the at least one identifier.

33. The apparatus of claim 31, further comprising:

means for inserting the at least one identifier into the second signal field to define the first signal field.

34. The apparatus of claim 31, further comprising:

means for performing XOR operation between at least one bit of the second signal field and at least one bit of the at least one identifier to define the first signal field.

35. The apparatus of claim 31, further comprising:

means for dividing the second signal field into a plurality of sub-fields; and

means for altering bits in one or more of the sub-fields.

36. The apparatus of claim 35, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

37. The apparatus of claim 36, further comprising:

means for providing the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field to an apparatus associated with the at least one identifier.

38. The apparatus of claim 31, further comprising:

means for scrambling bits of the second signal field based on the at least one identifier to define the first signal field.

39. The apparatus of claim 31, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

40. The apparatus of claim 39, further comprising:

means for providing information related to the alteration to an apparatus associated with the destination ID.

41. The apparatus of claim 39, further comprising:

means for indicating, to an apparatus associated with the destination ID, a procedure used for the alteration.

42. The apparatus of claim 31, wherein the at least one identifier comprises a group ID, and the apparatus further comprising:

means for indicating, to an apparatus associated with the group ID, a procedure used for the alteration.

43. The apparatus of claim 31, wherein:

the checksum is placed in a header of the packet being transmitted in accordance with IEEE 802.11 family of wireless communications standards, and

the header comprises a service field of the packet.

44. The apparatus of claim 31, wherein the second signal field comprises at least one of a Very High Throughput Signal field type A or a Very High Throughput Signal field type B of the packet transmitted in accordance with IEEE 802.11 family of wireless communications standards.

45. The apparatus of claim 31, wherein the at least one identifier comprises at least one of:

an association identification (AID) of a source apparatus transmitting the packet, an AID of a destination apparatus, or a Basic Service Set Identification (BSSID) of an access point serving at least one of the source apparatus or the destination apparatus.

46. A computer-program product for communications, comprising a computer-readable medium comprising instructions executable to:

define a first signal field by altering a second signal field, wherein the alteration is based on at least one identifier;

generate a checksum for the first signal field; and

transmit a packet comprising the second signal field with the checksum generated for the first signal field therein.

47. An access point, comprising:

at least one antenna;

a first circuit configured to define a first signal field by altering a second signal field, wherein the alteration is based on at least one identifier;

a second circuit configured to generate a checksum for the first signal field; and

a transmitter configured to transmit, via the at least one antenna, a packet comprising the second signal field with the checksum generated for the first signal field therein.

48. An apparatus for communications, comprising:

a receiver configured to receive a packet comprising a first signal field with a checksum therein;

a first circuit configured to define a second signal field by altering the first signal field, wherein the alteration is based on at least one identifier;

a second circuit configured to generate a checksum for the second signal field; and

a third circuit configured to compare the generated checksum with the received checksum, and

to determine that the packet is associated with the at least one identifier if the generated checksum matches the received checksum.

49. The apparatus of claim 48, wherein locations of bits of the first signal field modified during the alteration are determined based on the at least one identifier.

50. The apparatus of claim 48, wherein the first circuit is also configured to:

insert the at least one identifier into the first signal field to define the second signal field.

51. The apparatus of claim 48, wherein the first circuit is also configured to:

perform XOR operation between at least one bit of the first signal field and at least one bit of the at least one identifier.

52. The apparatus of claim 48, wherein the first circuit is also configured to:

divide the first signal field into a plurality of sub-fields; and

alter bits in one or more of the sub-fields.

53. The apparatus of claim 52, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

54. The apparatus of claim 53, wherein the receiver is also configured to:

receive signaling of the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field.

55. The apparatus of claim 48, wherein the first circuit is also configured to:

scramble bits of the first signal field based on the at least one identifier to define the second signal field.

56. The apparatus of claim 48, wherein:

the receiver is also configured to receive signaling information related to the alteration, and

the first circuit is also configured to define the second signal field based on the signaling information.

57. The apparatus of claim 48, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

58. The apparatus of claim 57, wherein the receiver is also configured to:

receive an indication about a procedure used for computing the received checksum at an apparatus associated with the source ID.

59. The apparatus of claim 48, wherein:

the at least one identifier comprises a group ID, and

the receiver is also configured to receive an indication about a procedure used for computing the received checksum at an apparatus associated with the group ID.

60. The apparatus of claim 48, wherein the second signal field is created from the first signal field if another checksum generated for the first signal field does not match the received checksum.

61. The apparatus of claim 48, wherein the third circuit is also configured to:

disable further processing of the packet by the apparatus, if the generated checksum does not match the received checksum.

62. A method for communications, comprising:

receiving a packet comprising a first signal field with a checksum therein;

defining a second signal field by altering the first signal field, wherein the alteration is based on at least one identifier;

generating a checksum for the second signal field;

comparing the generated checksum with the received checksum; and

determining that the packet is associated with the at least one identifier if the generated checksum matches the received checksum.

63. The method of claim 62, wherein locations of bits of the first signal field modified during the alteration are determined based on the at least one identifier.

64. The method of claim 62, wherein defining the second signal field comprises:

inserting the at least one identifier into the first signal field.

65. The method of claim 62, wherein defining the second signal field comprises:

performing XOR operation between at least one bit of the first signal field and at least one bit of the at least one identifier.

66. The method of claim 62, wherein defining the second signal field comprises:

dividing the first signal field into a plurality of sub-fields; and

altering bits in one or more of the sub-fields.

67. The method of claim 66, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

68. The method of claim 67, further comprising:

receiving signaling of the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field.

69. The method of claim 62, wherein defining the second signal field comprises:

scrambling bits of the first signal field based on the at least one identifier.

70. The method of claim 62, further comprising:

receiving signaling information related to the alteration, and

defining the second signal field based on the signaling information.

71. The method of claim 62, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

72. The method of claim 71, further comprising:

receiving an indication about a procedure used for computing the received checksum at an apparatus associated with the source ID.

73. The method of claim 62, wherein the at least one identifier comprises a group ID, and the method further comprising:

receiving an indication about a procedure used for computing the received checksum at an apparatus associated with the group ID.

74. The method of claim 62, wherein the second signal field is created from the first signal field if another checksum generated for the first signal field does not match the received checksum.

75. The method of claim 62, further comprising:

disabling further processing of the packet, if the generated checksum does not match the received checksum.

76. An apparatus for communications, comprising:

means for receiving a packet comprising a first signal field with a checksum therein;

means for defining a second signal field by altering the first signal field, wherein the alteration is based on at least one identifier;

means for generating a checksum for the second signal field;

means for comparing the generated checksum with the received checksum; and

means for determining that the packet is associated with the at least one identifier if the generated checksum matches the received checksum.

77. The apparatus of claim 76, wherein locations of bits of the first signal field modified during the alteration are determined based on the at least one identifier.

78. The apparatus of claim 76, further comprising:

means for inserting the at least one identifier into the first signal field to define the second signal field.

79. The apparatus of claim 76, further comprising:

means for performing XOR operation between at least one bit of the first signal field and at least one bit of the at least one identifier to define the second signal field.

80. The apparatus of claim 76, further comprising:

means for dividing the first signal field into a plurality of sub-fields; and

means for altering bits in one or more of the sub-fields.

81. The apparatus of claim 80, wherein:

the plurality of sub-fields comprise a first non-altered sub-field and a second non-altered sub-field, and

at least one of a size of the first non-altered sub-field or a size of the second non-altered sub-field is based on the at least one identifier.

82. The apparatus of claim 81, wherein the means for receiving is further configured to:

receive signaling of the at least one of the size of first non-altered sub-field or the size of second non-altered sub-field.

83. The apparatus of claim 76, further comprising:

means for scrambling bits of the first signal field based on the at least one identifier to define the second signal field.

84. The apparatus of claim 76, wherein:

the means for receiving is further configured to receive signaling information related to the alteration, and the apparatus further comprising

means for defining the second signal field based on the signaling information.

85. The apparatus of claim 76, wherein the at least one identifier comprises at least one of a source ID or a destination ID.

86. The apparatus of claim 85, wherein the means for receiving is further configured to:

receive an indication about a procedure used for computing the received checksum at an apparatus associated with the source ID.

87. The apparatus of claim 76, wherein:

the at least one identifier comprises a group ID, and

the means for receiving is further configured to receive an indication about a procedure used for computing the received checksum at an apparatus associated with the group ID.

88. The apparatus of claim 76, wherein the second signal field is created from the first signal field if another checksum generated for the first signal field does not match the received checksum.

89. The apparatus of claim 76, further comprising:

means for disabling further processing of the packet by the apparatus, if the generated checksum does not match the received checksum.

90. A computer-program product for communications, comprising a computer-readable medium comprising instructions executable to:

receive a packet comprising a first signal field with a checksum therein;

define a second signal field by altering the first signal field, wherein the alteration is based on at least one identifier;

generate a checksum for the second signal field;

compare the generated checksum with the received checksum; and

determine that the packet is associated with the at least one identifier if the generated checksum matches the received checksum.

91. An access terminal, comprising:

at least one antenna;

a receiver configured to receive, via the at least one antenna, a packet comprising a first signal field with a checksum therein;

a first circuit configured to define a second signal field by altering the first signal field, wherein the alteration is based on at least one identifier;

a second circuit configured to generate a checksum for the second signal field; and

a third circuit configured to compare the generated checksum with the received checksum, and

to determine that the packet is associated with the at least one identifier if the generated checksum matches the received checksum.