WIRELESS SENSOR NETWORKS

• US 20140232555A1
• Filed: 06/13/2012
• Published: 08/21/2014
• Est. Priority Date: 06/24/2011
• Status: Active Grant

• Current Assignee: Draeger Safety Incorporated (Dragerwerk AG)
• Original Assignee: GasSecure AS (FPS Vermögensverwaltung GmbH)
• Inventors: Aakvaag, Niels, Sandven, Knut
• Granted Patent: US 10,075,911 B2
• Time in Patent Office: Days
• US Class Current: 340/870.09
• CPC Class Codes: H04W 4/38 for collecting sensor information
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 52/0209 in terminal devices terminal devices per se H04W88/02
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless sensor network comprises at least one sensor unit which comprises a sensor for sensing a parameter and at least one interrogating node. The interrogating node is arranged to transmit an interrogation message periodically to said sensor unit and to receive a reply message from said sensor unit. The sensor unit is arranged to transmit said reply message after a predetermined deliberate delay unless the sensor unit determines that an alarm condition has been met, in which case the sensor unit is arranged to transmit said reply message before the end of the deliberate delay.

Claims

1-49. -49. (canceled)

50. A wireless sensor network comprising:

at least one sensor unit comprising a sensor for sensing a parameter and at least one interrogating node, wherein the interrogating node is arranged to transmit an interrogation message periodically to said sensor unit and to receive a reply message from said sensor unit, wherein the sensor unit is arranged to transmit said reply message after a predetermined deliberate delay unless the sensor unit determines that an alarm condition has been met, in which case the sensor unit is arranged to transmit said reply message before the deliberate delay ends.

51. The network of claim 50 wherein the interrogating node is arranged to pass on interrogation messages generated by another device.

52. The network of claim 50 wherein the reply message comprises a different, alarm message if an alarm condition is detected.

53. The network of claim 50 wherein the reply message comprises quantitative data related to a parameter sensed by the sensor unit.

54. The network of claim 50 wherein the sensor unit is arranged to send a message repeatedly, more often than a normal reply message, if an alarm condition is detected.

55. The network of claim 50 wherein the reply message includes identification information for identifying the sensor unit.

56. The network of claim 50 wherein the interrogating node communicates with a plurality of sensor units.

57. The network of claim 50 wherein one or more sensor units is arranged to relay messages and/or data for other sensor units or network nodes.

58. The network of claim 50 comprising a plurality of interrogating nodes connected together and/or to a central server by a data network.

59. The network of claim 50 wherein the sensor unit is arranged to transmit said reply message as soon as possible after an alarm condition is detected.

60. The network of claim 50 wherein the deliberate delay in the sensor unit is arranged so that the reply to the interrogation message is sent shortly before the next interrogation message is received.

61. The network of claim 50 wherein the interrogation messages are transmitted with a period T and the deliberate delay is more than 80% of T.

62. The network of claim 50 wherein the interrogating node is controlled to send request messages more frequently in the event of an alarm message being received.

63. The network of claim 62 wherein the interrogating node is caused to send a control message to the sensor unit to cause the sensor unit to reduce the deliberate delay accordingly.

64. The network of claim 50 wherein the sensor unit comprises a gas sensor.

65. A sensor unit for a wireless sensor network, wherein the sensor unit comprises:

a sensor for sensing a parameter, and the sensor unit is arranged to receive an interrogation message periodically from an interrogating node and to transmit a reply to said interrogating node after a predetermined deliberate delay unless the sensor unit determines that an alarm condition has been met, in which case the sensor unit is arranged to transmit said reply before the deliberate delay ends.

66. The sensor unit of claim 65 wherein the reply message comprises a different, alarm message if an alarm condition is detected.

67. The sensor unit of claim 65 wherein the reply message comprises quantitative data related to a parameter sensed by the sensor unit.

68. The sensor unit of claim 65 arranged to send a message repeatedly, more often than a normal reply message, if an alarm condition is detected.

69. The sensor unit of claim 65 wherein the reply message includes identification information for identifying the sensor unit.

70. The sensor unit of claim 65 arranged to relay messages and/or data for other sensor units or network nodes.

71. The sensor unit of claim 65 wherein the sensor unit is arranged to transmit said reply message as soon as possible after an alarm condition is detected.

72. The sensor unit of claim 65 wherein the deliberate delay is arranged so that the reply to the interrogation message is sent shortly before the next interrogation message is received.

73. The sensor unit of claim 65 wherein the deliberate delay is more than 80% of T, where T is the period between receipt of the interrogation messages.

74. The sensor unit of claim 65 comprising a gas sensor.