SYSTEMS AND METHODS FOR SYNCHRONIZING OPTICAL TRANSMITTERS
First Claim
1. An asset tracking system, comprising:
- a wireless network having a plurality of nodes configured to communicate wireless electrical signals via a first electrical channel, the nodes having optical transmitters configured to transmit wireless optical signals via an optical channel that is time-division multiplexed among the nodes, wherein messages communicated via the first electrical channel hop from node-to-node through the network, and wherein one of the wireless optical signals from one of the nodes includes a room identifier identifying a room of a building in which the one node is located;
a tag configured to receive the wireless optical signals, including the one wireless optical signal having the room identifier, the tag further configured to transmit a first message via a wireless electrical signal to one of the nodes via a second electrical channel, wherein the first message includes the room identifier, and wherein the nodes are configured to transmit the first message via the first electrical channel; and
a server configured to receive the first message from the nodes and to determine a location of the tag based on the room identifier, the server further configured to transmit a second message for controlling the tag to the nodes via the first electrical channel, wherein at least one of the nodes is configured to transmit the second message to the tag via the second electrical channel,wherein the nodes are configured to transmit an electrical synchronization signal via the first electrical channel and to synchronize the optical transmitters based on the electrical synchronization signal.
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Abstract
A wireless network has a plurality of nodes that are configured to communicate electrical signals via a backhaul channel in which messages hop from node-to-node through the network. The nodes have optical transmitters for communicating with tags via an optical channel that is time division multiplexed (TDM) among the nodes of the network. The nodes are configured to transmit an electrical synchronization signal via the backhaul channel and to synchronize transmissions for the optical channel based on the electrical synchronization signal. Thus, use of the backhaul channel to communicate the synchronization signal leverages the existing framework of the network in order to synchronize the optical transmitters without requiring specialized synchronization circuitry, and a robust TDM algorithm can be implemented for the optical channel with relatively low complexity and costs.
21 Citations
18 Claims
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1. An asset tracking system, comprising:
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a wireless network having a plurality of nodes configured to communicate wireless electrical signals via a first electrical channel, the nodes having optical transmitters configured to transmit wireless optical signals via an optical channel that is time-division multiplexed among the nodes, wherein messages communicated via the first electrical channel hop from node-to-node through the network, and wherein one of the wireless optical signals from one of the nodes includes a room identifier identifying a room of a building in which the one node is located; a tag configured to receive the wireless optical signals, including the one wireless optical signal having the room identifier, the tag further configured to transmit a first message via a wireless electrical signal to one of the nodes via a second electrical channel, wherein the first message includes the room identifier, and wherein the nodes are configured to transmit the first message via the first electrical channel; and a server configured to receive the first message from the nodes and to determine a location of the tag based on the room identifier, the server further configured to transmit a second message for controlling the tag to the nodes via the first electrical channel, wherein at least one of the nodes is configured to transmit the second message to the tag via the second electrical channel, wherein the nodes are configured to transmit an electrical synchronization signal via the first electrical channel and to synchronize the optical transmitters based on the electrical synchronization signal.
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2. An asset tracking system, comprising:
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a wireless network having a plurality of nodes configured to communicate wireless electrical signals via a first electrical channel, the nodes having optical transmitters configured to transmit wireless optical signals via an optical channel that is time-division multiplexed among the nodes, wherein messages communicated via the first electrical channel hop from node-to-node through the network; and a tag configured to receive the wireless optical signals from the nodes via the optical channel, wherein the nodes are configured to transmit an electrical synchronization signal via the first electrical channel and to synchronize the optical transmitters based on the electrical synchronization signal. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for use in an asset tracking system, comprising:
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communicating wireless electrical signals among nodes of a wireless network via a first electrical channel; monitoring a location of a tag based on the wireless electrical signals; transmitting wireless optical signals from optical transmitters of the nodes to the tag via an optical channel that is time-division multiplexed among the nodes; transmitting an electrical synchronization signal among the nodes via the first electrical channel; and synchronizing the optical transmitters based on the electrical synchronization signal. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification