Wireless communication system with channel hopping and redundant connectivity

• US 20050281215A1
• Filed: 06/17/2004
• Published: 12/22/2005
• Est. Priority Date: 06/17/2004
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Budampati, Ramakrishna S., Gonia, Patrick S., Kolavennu, Soumitri N.
• Granted Patent: US 7,620,409 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

A wireless system having an infrastructure node and several leaf nodes in a non-redundant version or having at least two infrastructure nodes and several leaf nodes in a redundant version. Leaf nodes may individually seek out timing information in order to be in synch with an infrastructure node. Upon receipt of synch information from an infrastructure node, the respective leaf node may send data to the infrastructure node. In the case of a redundant system, primary and secondary nodes may be selected from a list of infrastructure nodes. Communications between an infrastructure node and a leaf node may occur on one of a number of channels, and the channel may be changed for communications between the nodes. In the case of a redundant system, a single transmission from the leaf node is received simultaneously by the redundant infrastructure nodes.

Claims

1. A wireless system comprising:

at least one initiating device; and

a responding device; and

wherein;

the responding device occasionally has an interruption in its normal operation to listen for a transmission from an initiating device;

the initiating device repeatedly sends a transmission of tightly packed messages requesting time synchronization information with minimum spacing allowing time between transmissions for receiving a response;

the responding device receives the transmission from the initiating device during an interruption; and

the responding device sends time synchronization information to the initiating device immediately following a reception of the transmission from the initiating device.

2. The system of claim 1, wherein:

the initiating and responding devices may communicate on more than one channel selected from a list of channels;

each interruption of the responding device is sufficiently long to receive a transmission of at least one message requesting time synchronization information; and

the responding device remains on the same channel during the interruptions for a selected number of interruptions for receiving a transmission from the initiating device.

3. The system of claim 2, wherein:

the initiating device transmits a message requesting time synchronization information on all channels that are used by the responding device during a plurality of interruptions within the selected number of interruptions; and

the responding device receives the message requesting time synchronization information.

4. The system of claim 3, wherein the responding device transmits time synchronization information to the initiating device on the same channel that the transmission from the initiating device was received by the responding device.

5. The system of claim 4, wherein the transmission sent by the initiating device includes a request for an allocation of periodic communication time from the responding device.

6. The system of claim 4, wherein the responding device sends at least one allocation of periodic communication time from an available budget of time.

7. The system of claim 6, wherein the allocation of periodic communication time is included with the time synchronization information sent by the responding device to the initiating device.

8. The system of claim 6, wherein the initiating device may send one or more transmissions within a time slot of an allocation of periodic communication time.

9. The system of claim 8, wherein the one or more transmissions may comprise at least one re-transmission.

10. The system in claim 8, wherein the initiating device operates in a reduced power consumption mode when not communicating with the responding device.

11. The system of claim 8, wherein the responding device receives a transmission on a channel from the list of channels.

12. The system of claim 11, wherein the initiating device provides, in a message requesting time synchronization information, sufficient information to allow the responding device to be aware of the channel for use by the initiating device in future transmissions.

13. The system of claim 12, wherein the responding device sends a reply to the initiating device within the allocation of periodic communication time in response to a transmission received from the initiating device.

14. The system of claim 13, wherein the reply to the initiating device includes the time synchronization information.

15. The system of claim 11, wherein a channel to be used by the initiating device changes for each allocation of periodic communication time.

16. The system of claim 11, wherein a channel to be used by the initiating device changes for each transmission within each allocation of periodic communication time.

17. The system of claim 15, wherein the channel is pseudo randomly selected.

18. The system of claim 15, wherein the channel is determined by a frequency hopping pattern.

19. The system of claim 15, wherein the channel is determined by a direct sequence spread spectrum channel code value.

20. The system of claim 4, wherein the interruption is sufficiently long to receive a transmission of at least two successive messages requesting time synchronization information.

21. The system of claim 20, wherein:

the initiating device repeatedly sends the transmission of tightly packed messages requesting time synchronization information on channels selected from a series of sequences of channels, for a period of time during and in between a number of interruptions equal to or greater than the selected number of interruptions;

each sequence of channels contains all channels from the list of channels in a different permutation;

a message requesting time synchronization information is transmitted on each channel from the sequence of channels; and

each sequence of channels from the series of sequences of channels is used for transmissions of the message requesting time synchronization information such that the message requesting time synchronization information is transmitted on all channels from the list of channels during the selected number of interruptions.

22. A wireless system comprising:

at least one initiating device; and

at least two responding devices; and

wherein;

each responding device occasionally has an interruption in its normal operation to listen for a transmission from an initiating device;

each responding device is synchronized to a system clock;

an initiating device repeatedly sends a transmission of tightly packed messages requesting time synchronization information with minimum spacing, allowing time between transmissions for receiving a response;

one or more responding devices receive the transmission from the initiating device during an interruption; and

a responding device that first receives a transmission from the initiating device during an interruption sends time synchronization information to the initiating device.

23. The system of claim 22, wherein

the initiating and responding devices may communicate on more than one channel selected from a list of channels;

the interruption is sufficiently long to receive a transmission of at least one message requesting time synchronization information; and

each responding device remains on the same channel during the interruptions for a selected number of interruptions for receiving a transmission from the initiating device.

24. The system of claim 23, wherein:

the initiating device sends a transmission of messages requesting time synchronization information on all channels that are used by the responding devices, during a plurality of interruptions within the selected number of interruptions; and

a responding device receives the transmission of messages requesting time synchronization information.

25. The system of claim 24, wherein the responding device that receives the transmission from the initiating device, transmits time synchronization information to the initiating device on the same channel that the transmission from the initiating device was received by the responding device.

26. The system of claim 25, wherein the initiating device, after receiving time synchronization information, operates in a reduced power consumption mode for an amount of time.

27. The system of claim 26, wherein the time synchronization information includes the amount of time that the initiating device should operate in a reduced power consumption mode.

28. The system of claim 26, wherein the initiating device repeatedly sends a transmission of tightly packed messages requesting link quality information with minimum spacing allowing time between transmissions for receiving a response, after operating in the reduced power consumption mode for the amount of time.

29. The system of claim 28, wherein the initiating device sends the transmission of messages requesting link quality information on all channels that are used by the responding devices.

30. The system of claim 29, wherein the transmissions occur during the interruptions for a selected number of interruptions.

31. The system of claim 29, wherein:

each interruption is sufficiently long to receive a transmission of at least one message requesting link quality information;

one or more responding devices may receive the transmission from the initiating device during an interruption;

each responding device that receives the transmission from the initiating device sends a message containing link quality information to the initiating device on the same channel that the transmission from the initiating device was received by the responding device; and

each responding device provides in the message containing link quality information, a temporary allocation of communication time from an available budget of time during its normal operation and a channel from the list of channels.

32. The system of claim 31, wherein:

the initiating device receives the message containing link quality information from each responding device that receives the transmission from the initiating device; and

the initiating device adds the message from each responding device to a list of messages.

33. The system of claim 32, wherein the initiating device stops the transmission of messages requesting link quality information when a number of messages in the list of messages exceeds a selected number of messages.

34. The system of claim 32, wherein the initiating device stops the transmission of messages requesting link quality information after a selected amount of time.

35. The system of claim 34, wherein the time synchronization information includes the selected amount of time that the initiating device repeatedly sends a transmission of messages requesting link quality information.

36. The system of claim 34, wherein:

the initiating device prepares a list of preferred responding devices from the list of messages;

the list of preferred responding devices is sorted in descending order of preference; and

the initiating device selects the first entry in the list of preferred responding devices as a best responding device.

37. The system of claim 36, wherein the initiating device operates in a reduced power consumption mode until the start of the temporary allocation of communication time provided by the best responding device.

38. The system of claim 36, wherein the initiating device transmits a message containing the list of preferred responding devices to the best responding device during the temporary allocation of communication time and on the channel from the list of channels provided by the best responding device.

39. The system of claim 38, wherein the message transmitted by the initiating device includes a request for an allocation of periodic communication time from the best responding device.

40. The system of claim 38, wherein the message transmitted by the initiating device contains sufficient information about the channel for use by the initiating device in future transmissions during its allocation of periodic communication time.

41. The system of claim 40, wherein the best responding device sends an acknowledgement to the initiating device after receiving the message containing the list of preferred responding devices.

42. The system of claim 41, wherein the acknowledgement includes an updated temporary allocation of communication time and an updated channel from the list of channels for use by the initiating device.

43. The system of claim 42, wherein the best responding device communicates with the responding devices in the list of preferred responding devices and selects an allocation of periodic communication time for the initiating device that is common to the available budgets of time of two or more responding devices and selects an order of preference of the two or more responding devices in the list of preferred responding devices.

44. The system of claim 42, wherein:

the best responding device communicates the list of preferred responding devices to a central time allocation entity;

the central time allocation entity selects an allocation of periodic communication time that is common to the available budgets of time of two or more responding devices in the list of preferred responding devices;

the central time allocation entity sends information about the allocation of periodic communication time for the initiating device and an order of preference of the two or more responding devices to the best responding device;

the best responding device sends a message containing the information about the allocation of periodic communication time for the initiating device and the order of preference of the two or more responding devices to the two or more responding devices; and

the message also includes sufficient information about the channel for use by the initiating device in future transmissions.

45. The system of claim 42, wherein:

the best responding device communicates the list of preferred responding devices and sufficient information about the channel for use by the initiating device in future transmissions to a central time allocation entity;

the central time allocation entity selects an allocation of periodic communication time that is common to the available budgets of time of two or more responding devices in the list of preferred responding devices;

the central time allocation entity sends information about the allocation of periodic communication time for the initiating device and an order of preference of the two or more responding devices to the best responding device and to the two or more responding devices; and

the central time allocation entity sends sufficient information about the channel for use by the initiating device in future transmissions to the two or more responding devices.

46. The system of claim 45, wherein the initiating device transmits an inquiry message to the best responding device on the updated channel from the list of channels during the updated temporary allocation of communication time.

47. The system of claim 46, wherein the best responding device, after receiving the inquiry message, sends the information about the allocation of periodic communication time and the order of preference of the two or more responding devices to the initiating device on the updated channel.

48. The system of claim 47, wherein:

the initiating device may send one or more transmissions within a time slot of an allocation of periodic communication time; and

the two or more responding devices receive the one or more transmissions on a channel from the list of channels.

50. The system of claim 48, wherein the initiating device operates in a reduced power consumption mode when not communicating with the two or more responding devices.

51. The system of claim 48, wherein each of the two or more responding devices send a reply to the initiating device, in the order of preference of the two or more responding devices, within the allocation of periodic communication time in response to a transmission received from the initiating device.

52. The system of claim 51, wherein the reply from each of the two or more responding devices to the initiating device includes time synchronization information.

53. The system of claim 40, wherein a channel to be used by the initiating device changes for each allocation of periodic communication time.

54. The system of claim 40, wherein a channel to be used by the initiating device changes for each transmission within each allocation of periodic communication time.

55. The system of claim 53, wherein the channel is pseudo randomly selected.

56. The system of claim 53, wherein the channel is determined by a frequency hopping pattern.

57. The system of claim 53, wherein the channel is determined by a direct sequence spread spectrum channel code value.

58. The system of claim 25, wherein the interruption is sufficiently long to receive a transmission of at least two successive messages requesting time synchronization information.

59. The system of claim 58, wherein:

the initiating device repeatedly sends the transmission of tightly packed messages requesting time synchronization information on channels selected from a series of sequences of channels, for a period of time during and in between a number of interruptions equal to or greater than the selected number of interruptions;

each sequence of channels contains all channels from the list of channels in a different permutation;

a message requesting time synchronization information is transmitted on each channel from the sequence of channels; and

each sequence of channels from the series of sequences of channels is used for transmissions of the message requesting time synchronization information such that the message requesting time synchronization information is transmitted on all channels from the list of channels during the selected number of interruptions.

49. The system of 48, wherein the one or more transmissions may comprise at least one re-transmission.

60. A wireless system comprising:

at least one initiating device; and

a responding device; and

wherein;

the at least one initiating device is time synchronized with the responding device;

the responding device has a normal operation of communicating with the at least one initiating device;

the at least one initiating device sends a message to the responding device within a designated time; and

the responding device occasionally has an interruption in its normal operation to carry out other activities.

61. The system of claim 60, wherein the activities comprise listening for a message requesting time synchronization information from another initiating device not time synchronized with the responding device.

62. The system of claim 60, wherein the initiating device operates in a reduced power consumption mode when not communicating with the responding device.

63. The system of claim 60, wherein the initiating and responding devices may communicate on more than one channel selected from a list of channels.

64. The system of claim 63, wherein the designated time is a time slot of an allocation of periodic communication time.

65. The system of claim 64, wherein the initiating device may send one or more transmissions within the designated time.

66. The system of claim 65, wherein the responding device receives a transmission from the initiating device on a channel from the list of channels during the designated time.

67. The system of claim 66, wherein the initiating device provides sufficient information to allow the responding device to be aware of the channel for use by the initiating device in future transmissions.

68. The system of claim 66, wherein the responding device provides sufficient information to allow the initiating device to be aware of the channel for use in future transmissions.

69. The system of claim 66, wherein the responding device sends a reply to the initiating device within the designated time in response to a transmission received from the initiating device.

70. The system of claim 69, wherein the one or more transmissions sent by the initiating device may comprise at least one re-transmission.

71. The system of claim 70, wherein the reply to the initiating device includes the time synchronization information.

72. The system of claim 66, wherein a channel to be used by the initiating device changes for each allocation of periodic communication time.

73. The system of claim 66, wherein a channel to be used by the initiating device changes for each transmission within each allocation of periodic communication time.

74. The system of claim 72, wherein the channel is pseudo randomly selected.

75. The system of claim 72, wherein the channel is determined by a frequency hopping pattern.

76. The system of claim 72, wherein the channel is determined by a direct sequence spread spectrum channel code value.

77. A wireless system comprising:

at least one initiating device; and

at least two responding devices; and

wherein;

the two or more responding devices have a normal operation of communicating with an initiating device;

the responding devices are synchronized to a system clock;

the at least one initiating device is time synchronized with the at least two responding devices; and

the initiating device sends a message to the responding devices within a designated time.

78. The system of claim 77, wherein the responding devices may occasionally have an interruption in their normal operation to carry out other activities.

79. The system of claim 78, wherein the activities comprise listening for a message requesting time synchronization information from another initiating device not time synchronized with the responding devices.

80. The system in claim 77, wherein the initiating device operates in a reduced power consumption mode when not communicating with the responding devices.

81. The system of claim 77, wherein the initiating device and the responding devices may communicate on more than one channel selected from a list of channels.

82. The system of claim 81, wherein the designated time is a time slot of an allocation of periodic communication time.

83. The system of claim 82, wherein the initiating device may send one or more transmissions within the designated time.

84. The system of claim 83, wherein the responding devices receive a transmission from the initiating device on a channel from the list of channels during the designated time.

85. The system of claim 84, wherein the initiating device provides sufficient information to allow the responding devices to be aware of the channel for use by the initiating device in future transmissions.

86. The system of claim 84, wherein the responding devices provides sufficient information to allow the initiating device to be aware of the channel for use in future transmissions.

87. The system of claim 84, wherein the responding devices may send replies to the initiating device within the designated time in response to a transmission received from the initiating device.

88. The system of claim 87, wherein only one of the responding devices sends the reply.

89. The system of claim 87, wherein the responding devices sequentially send replies to the initiating device.

90. The system of claim 87, wherein the one or more transmissions sent by the initiating device may comprise at least one re-transmission.

91. The system of claim 87, wherein the reply to the initiating device includes the time synchronization information.

92. The system of claim 84, wherein a channel to be used by the initiating device changes for each allocation of periodic communication time.

93. The system of claim 84, wherein a channel to be used by the initiating device changes for each transmission within each allocation of periodic communication time.

94. The system of claim 92, wherein the channel is pseudo randomly selected.

95. The system of claim 92, wherein the channel is determined by a frequency hopping pattern.

96. The system of claim 92, wherein the channel is determined by a direct sequence spread spectrum channel code value.