Inserting time of departure information in frames to support multi-channel location techniques
First Claim
1. A method comprising:
- generating a plurality of messages at a first device whose location is to be determined and time of departure (TOD) information that indicates when the respective messages are transmitted from the first device; and
wirelessly transmitting the plurality of messages and the TOD information from the first device, wherein the plurality of messages are transmitted such that at least two of the messages are on different radio frequency (RF) channels.
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Abstract
A device whose location is to be determined (target device) generates a plurality of frames (messages) and time of departure (TOD) timestamp information indicating when the target device transmits the plurality of frames in a sequence or burst. The target device transmits the plurality of frames and the TOD information, wherein the plurality of frames are transmitted such that at least two of the frames are on different radio frequency (RF) channels. Within a sequence or burst (or across multiple sequences or bursts), multiple widely spaced transmissions on the same channel are included to allow for estimation of the crystal frequency offset of the transmitting device. The TOD information included in the transmitted packets allows devices that receive the packets not to change their channels of operation solely for the purpose of receiving packets from the device to be located.
28 Citations
35 Claims
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1. A method comprising:
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generating a plurality of messages at a first device whose location is to be determined and time of departure (TOD) information that indicates when the respective messages are transmitted from the first device; and wirelessly transmitting the plurality of messages and the TOD information from the first device, wherein the plurality of messages are transmitted such that at least two of the messages are on different radio frequency (RF) channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 27)
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11. An apparatus comprising:
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a controller that is configured to generate a plurality of messages and time of departure (TOD) information that indicates when the respective messages are transmitted from a first device; and a transmitter coupled to the controller, wherein the transmitter is configured to wirelessly transmit the plurality of messages and the TOD information from the first device such that at least two of the messages are on different radio frequency (RF) channels. - View Dependent Claims (12, 13, 14, 15, 16, 28)
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17. Logic encoded in one or more non-transitory tangible media for execution and when executed operable to:
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generate a plurality of messages which are to be transmitted from a first device whose location is to be determined; generate time of departure (TOD) information that indicates when the respective messages are transmitted from the first device; and select radio frequency (RF) channels for wireless transmission of the plurality of messages such that at least two of the messages are transmitted on different RF channels. - View Dependent Claims (18, 19, 20, 21, 22, 29)
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23. A method comprising:
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receiving data representing time of arrival (TOA) of messages that are wireles sly transmitted on multiple radio frequency (RF) channels by a first device and received at multiple ones of a plurality of second devices, and time of departure (TOD) data that indicates when each of the plurality of messages was transmitted by the first device; and computing a location of the first device based on the TOA of the messages and the TOD data. - View Dependent Claims (24, 25, 26)
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30. A system comprising:
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a first device comprising; a controller configured to generate a plurality of messages and time of departure (TOD) information that indicates when the respective messages are transmitted from the first device; a transmitter coupled to the controller, wherein the transmitter is configured to wirelessly transmit the plurality of messages and the TOD information from the first device such that at least two of the messages are on different radio frequency (RF) channels; a plurality of second devices configured to receive one or more of the plurality of messages; and a server computer in communication with the plurality of second devices and configured to compute a location of the first device based on data associated with time of arrival (TOA) of the messages at multiple ones of the second devices and the information representing the TOD information associated with the plurality of messages. - View Dependent Claims (31, 32, 33, 34, 35)
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Specification