WIRELESS SENSOR NODE AND METHOD
First Claim
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1. A method of time-synchronizing a wireless sensor node of a mesh network, comprising:
- wirelessly receiving at the node, intermittently from an upstream node in the network, a plurality of beacon times each offset from a global time by a latency;
using a power-consuming resource of the node, determining the global time associated with a selected one of the beacon times;
computing the latency using the selected beacon time and the global time;
using the latency and without using the power-consuming resource, computing the global time corresponding to at least some of the beacon times; and
for each beacon time, recording the global time and a local time corresponding to that beacon time.
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Abstract
Determining time latency at a sensor node in a mesh network. A beacon time is received at the sensor node from an upstream node, the beacon time offset from global time by the latency. The latency, the global time, and a corresponding local time are determined at the sensor node.
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20 Claims
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1. A method of time-synchronizing a wireless sensor node of a mesh network, comprising:
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wirelessly receiving at the node, intermittently from an upstream node in the network, a plurality of beacon times each offset from a global time by a latency; using a power-consuming resource of the node, determining the global time associated with a selected one of the beacon times; computing the latency using the selected beacon time and the global time; using the latency and without using the power-consuming resource, computing the global time corresponding to at least some of the beacon times; and for each beacon time, recording the global time and a local time corresponding to that beacon time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A wireless sensor node, comprising:
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a wireless transceiver configured to intermittently receive beacon times from another node in a mesh network, each beacon time offset from a corresponding global time by a latency; a wireless receiver configured to receive the global time without the latency; a clock configured to provide a local ti and a controller configured to operate the wireless receiver to obtain the global time associated with a first beacon time, compute the latency using the first beacon time and the corresponding global time, using the latency, computing the global time corresponding to each of a set of subsequent beacon times without operating the wireless receiver, and record, for each beacon time, a timestamp of the global time and the corresponding local time. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of time-synchronizing data from wireless sensor nodes in a mesh network, comprising:
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providing an upstream node with an upstream local time not synchronized to a downstream local time of a downstream node; correlating, at the upstream node, the upstream local time to a global time; wirelessly transmitting a beacon time equal to the global time from the upstream node to the downstream node; wirelessly receiving the beacon time at the downstream node, the received beacon time value from the global time by a latency of the transmitting and the receiving; determining the latency at the downstream node; and at the downstream node, using the global time and the latency to correlate the downstream local time to the global time. - View Dependent Claims (19, 20)
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Specification