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- Nachgewiesen in: USPTO Patent Grants
- Sprachen: English
- Patent Number: 10849,084
- Publication Date: November 24, 2020
- Appl. No: 16/783827
- Application Filed: February 06, 2020
- Assignees: King Fahd University of Petroleum and Minerals (Dhahran, SA)
- Claim: 1. A system for monitoring at least one predetermined condition in a harsh environment, comprising: a plurality of wireless sensor nodes, each node including at least one sensor, a wireless communications device, a physical clock, and circuitry for a soft clock, the at least one sensor configured to detect the at least one predetermined condition; a gateway node including a wireless communications device and configured to maintain a gateway time value; a wireless communication network interconnecting the plurality of wireless sensor nodes and connecting at least one of the wireless sensor nodes to the gateway node; and an end-user computer device having access to the gateway node, wherein the wireless sensor nodes are configured to communicate time-stamped sensed data based on a local node time through the gateway node to the end-user device, each wireless sensor node is configured to remain in a sleep mode, then independently, when a triggering event is true, the circuitry for the soft clock evolves a value of a dynamical local time variable using time variable values communicated by at least one random other of the wireless sensor nodes that is within a single hop based on the harsh environment; infers from its dynamical local time variable the communication instant at which the dynamical local time variable is closest to the time value of the gateway node; and initializes the physical clock using the value of the dynamical local time variable at that instant to generate the local node time.
- Claim: 2. The system of claim 1 , wherein the end-user device is configured to assign a node ID to each of the wireless sensor nodes based on proximity to the gateway node; and initialize the dynamical local time variable of each wireless sensor node as a sequence based on the node ID; wherein the circuitry of each wireless sensor node is configured to calculate an update of the dynamical local time variable at an update time that is based on the number of network nodes including the gateway node; the wireless communication device of each wireless sensor node is configured to wirelessly exchange synchronization packets with the other neighbor sensor nodes that are within one hop, in which the wireless communications device of each wireless sensor node transmits a broadcast packet of its current local time information every predetermined time; when the update is calculated, the circuitry of each wireless sensor node independently updates the dynamical local time variable to an average estimate of current time information received in the synchronization packets from the neighbor sensor nodes; and when a request for the local time variable value is not received for a second predetermined period of time, each wireless sensor node independently transitions to the sleep mode.
- Claim: 3. The system of claim 1 , wherein the circuitry of each wireless sensor node is configured to independently update the dynamical local time variable asynchronously based on a wake-up from a sleep activation procedure regulated by the gateway node; and wherein the gateway node is configured to regulate the activation of the wireless sensor nodes by flooding the network with wake-up messages in every cycle of asynchronous update.
- Claim: 4. The system of claim 3 , wherein the circuitry of each wireless sensor node is configured to independently maintain a binary status variable, wherein the gateway node initializes an update timer and triggers the update of the wireless sensor nodes connected to it; once the circuitry of a wireless sensor node updates its dynamical local time variable, it triggers the update of its nearest neighbor sensor nodes; if the neighbor wireless sensor node receives a time value and the binary status variable is a complement of the triggering wireless sensor node, the neighbor wireless sensor node accepts the time value and the circuitry computes an average time as an update to its dynamical local time variable; and if the binary status variable value is the same, the neighbor wireless sensor node does not wakeup from the sleep mode to compute and update its dynamical local time variable.
- Claim: 5. The system of claim 1 , wherein the gateway node is configured to trigger the update of the wireless sensor nodes by broadcasting its clock values and the wireless sensor nodes update their dynamical local time variables; wherein when a wireless sensor node is the farthest node, a backward flooding is triggered and wireless sensor node updating continues until the first layer of the wireless sensor nodes is reached; and wherein when the first layer is reached, forward flooding to reach the farthest node is again triggered.
- Claim: 6. The system of claim 1 , wherein a number of the wireless sensor nodes interconnected in the wireless communication network is increased.
- Claim: 7. The system of claim 1 , wherein each of the wireless sensor nodes initially start with random values for their dynamical local time variable.
- Claim: 8. The system of claim 1 , wherein each wireless sensor node is configured to operate its physical clock during sleep mode in order to monitor a time period until a wireless sensor node wakes up from the sleep mode.
- Claim: 9. The system of claim 2 , wherein when a configuration of the wireless sensor nodes interconnected in the wireless communications network changes, the end-user device is configured to reassign a node ID to each of the wireless sensor nodes based on proximity to the gateway node; and reinitialize the dynamical local time variable of each wireless sensor node as a sequence based on the node ID; wherein the circuitry of each wireless sensor node is configured to calculate an update of the dynamical local time variable at an update time based on a number of network nodes in the changed wireless communications network including the gateway node.
- Claim: 10. The system of claim 5 , wherein the gateway node is configured to trigger the update of the wireless sensor nodes by broadcasting its clock values to the wireless sensor nodes and the wireless sensor nodes update their dynamical local time variables, wherein at least one of the wireless sensor nodes has failed and cannot update its dynamic local time variable.
- Claim: 11. A method of monitoring at least one predetermined condition in a harsh environment, performed in a system including a plurality of wireless sensor nodes, each node including at least one sensor, a wireless communications device, a physical clock, and circuitry for a soft clock, the at least one sensor configured to detect the at least one predetermined condition; a gateway node including a wireless communications device and configured to maintain a gateway time value; a wireless communication network interconnecting the plurality of wireless sensor nodes and connecting at least one of the wireless sensor nodes to the gateway node; and an end-user computer device having access to the gateway node, wherein the wireless sensor nodes are configured to communicate time-stamped sensed data based on a local node time through the gateway node to the end-user device, each wireless sensor node is configured to remain in a sleep mode, then independently, when a triggering event is true, the method, performed by circuitry for the soft clock, comprising: evolving a value of a dynamical local time variable using time variable values communicated by at least one random other of the wireless sensor nodes that is within a single hop based on the harsh environment; inferring from its dynamical local time variable the communication instant at which the dynamical local time variable is closest to the time value of the gateway node; and initializing the physical clock using the value of the dynamical local time variable at that instant to generate the local node time.
- Claim: 12. The method of claim 11 , further comprising: wherein the end-user device is configured to assigning, by the end user device, a node ID to each of the wireless sensor nodes based on proximity to the gateway node; and initializing, by the end-user device, the dynamical local time variable of each wireless sensor node as a sequence based on the node ID; calculating, by the wireless sensor node, an update of the dynamical local time variable at an update time that is based on the number of network nodes including the gateway node; wirelessly exchanging, by the wireless communication device of each wireless sensor node, synchronization packets with the other neighbor sensor nodes that are within one hop, in which the wireless communications device of each wireless sensor node transmits a broadcast packet of its current local time information every predetermined time; when the update is calculated, independently updating, by each wireless sensor node, the dynamical local time variable to an average estimate of current time information received in the synchronization packets from the neighbor sensor nodes; and when a request for the local time variable value is not received for a second predetermined period of time, independently transitioning, by each wireless sensor node, to the sleep mode.
- Claim: 13. The method of claim 11 , further comprising: independently updating, by each wireless sensor node, the dynamical local time variable asynchronously based on a wake-up from a sleep activation procedure regulated by the gateway node; and regulating, by the gateway node, the activation of the wireless sensor nodes by flooding the network with wake-up messages in every cycle of asynchronous update.
- Claim: 14. The method of claim 13 , further comprising: independently maintaining, by each wireless sensor node, a binary status variable, initializing, by the gateway node, an update timer and triggering the update of the wireless sensor nodes connected to it; once the circuitry of a wireless sensor node updates its dynamical local time variable, triggering, by the wireless sensor node, the update of its nearest neighbor sensor nodes; if the neighbor wireless sensor node receives a time value and the binary status variable is a complement of the triggering wireless sensor node, accepting, by the neighbor wireless sensor node, the time value and computing an average time as an update to its dynamical local time variable; and if the binary status variable value is the same, the neighbor wireless sensor node does not wakeup from the sleep mode to compute and update its dynamical local time variable.
- Claim: 15. The method of claim 11 , further comprising: triggering, by the gateway node, the update of the wireless sensor nodes by broadcasting its clock values and updating, by the wireless sensor nodes, their dynamical local time variables; wherein when a wireless sensor node is the farthest node, a backward flooding is triggered and wireless sensor node updating continues until the first layer of the wireless sensor nodes is reached, and wherein when the first layer is reached, forward flooding to reach the farthest node is again triggered.
- Claim: 16. The method of claim 11 , further comprising: increasing a number of the wireless sensor nodes interconnected in the wireless communication network.
- Claim: 17. The method of claim 11 , further comprising: initially starting each of the wireless sensor nodes with random values for their dynamical local time variable.
- Claim: 18. The method of claim 11 , further comprising: operating the physical clock of each wireless sensor node during sleep mode in order to monitor a time period until a wireless sensor node wakes up from the sleep mode.
- Claim: 19. The method of claim 12 , wherein when a configuration of the wireless sensor nodes interconnected in the wireless communications network changes, the method further comprising: reassigning, by the end-user device, a node ID to each of the wireless sensor nodes based on proximity to the gateway node; reinitializing, by the end-user device, the dynamical local time variable of each wireless sensor node as a sequence based on the node ID; and calculating, by each wireless sensor node, an update of the dynamical local time variable at an update time based on a number of network nodes in the changed wireless communications network including the gateway node.
- Claim: 20. The method of claim 15 , further comprising: triggering, by the gateway node, the update of the wireless sensor nodes by broadcasting its clock values to the wireless sensor nodes; and updating, by the wireless sensor nodes, their dynamical local time variables, wherein at least one of the wireless sensor nodes has failed and cannot update its dynamic local time variable.
- Patent References Cited: 10143038 November 2018 Stamatakis ; 2006/0271661 November 2006 Qi ; 2008/0253327 October 2008 Kohvakka ; 2009/0252087 October 2009 Jiang ; 2010/0316009 December 2010 Han ; 108900273 November 2018 ; 3 253 139 February 2019 ; 10-1510893 April 2015
- Other References: Ramadan Abdul-Rashid, et al., “Accurate, Energy-Efficient, Decentralized, Single-Hop, Asynchronous Time Synchronization Protocols for Wireless Sensor Networks”, ARXIV:1811.01152v1, [eess.SP], https://arxiv.org/pdf/1811.01152.pdf, Nov. 3, 2018, pp. 1-19. cited by applicant
- Primary Examiner: Heiber, Shantell L
- Attorney, Agent or Firm: Oblon, McClelland, Maier & Neustadt, L.L.P.
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