Location system
First Claim
1. A system for determining a location of a mobile receiver unit, the system comprising:
- a plurality of static transmitter units, each comprising a respective radio transmitter and a respective clock, and being configured to use the respective clock to transmit a respective positioning signal according to a respective transmission schedule;
one or more radio gateways for communicating with the static transmitter units by radio, each radio gateway comprising a respective clock;
a scheduling server, communicatively coupled to the plurality of static transmitter units and to the one or more radio gateways;
a mobile receiver unit configured to receive a positioning signal from any of the static transmitter units; and
a location-determining server, wherein the scheduling server is configured to;
use information representing a respective drift or offset of each of the respective clocks of the static transmitter units to generate the respective transmission schedules for the respective static transmitter units, each transmission schedule instructing a respective static transmitter unit to transmit the respective positioning signal at one or more scheduled times according to the clock of the static transmitter unit, by (i) determining information representing a device graph, the device graph comprising the one or more radio gateways and the static transmitter units, wherein a pair of devices is connected in the device graph when the scheduling server has received information representing the drift or offset of respective clocks of the pair of devices, satisfying one or more quality criteria, that enables the scheduling server to map time between the respective clocks of the pair of devices, and (ii) for each static transmitter unit, determining a respective shortest path through the device graph between a reference radio gateway of the one or more radio gateways and the static transmitter unit, and composing relative offset or drift information for devices along the respective shortest path in order to map a respective time or time period from the clock of the reference radio gateway to the clock of the respective static transmitter unit; and
send the respective transmission schedules to the respective static transmitters units;
wherein the mobile receiver unit is configured to send information derived from a positioning signal, received from any of the static transmitter units, to the location-determining server, andwherein the location-determining server is configured to use the information sent by the mobile receiver unit to determine the location of the mobile receiver unit.
1 Assignment
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Accused Products
Abstract
A system for determining the location of a mobile receiver unit includes static transmitter units, each including a respective clock which it uses to transmit a positioning signal according to a respective transmission schedule. The mobile receiver unit receives a positioning signal from any of the static transmitter units. A first processing means uses information relating to the received positioning signal to determine the location of the mobile receiver unit. A second processing means uses information relating to a respective drift and/or offset of each of the clocks of the static transmitter units to generate transmission schedules for the static transmitter units. Each transmission schedule instructs a respective static transmitter unit to transmit a positioning signal at one or more scheduled times according to the clock of the static transmitter unit.
7 Citations
27 Claims
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1. A system for determining a location of a mobile receiver unit, the system comprising:
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a plurality of static transmitter units, each comprising a respective radio transmitter and a respective clock, and being configured to use the respective clock to transmit a respective positioning signal according to a respective transmission schedule; one or more radio gateways for communicating with the static transmitter units by radio, each radio gateway comprising a respective clock; a scheduling server, communicatively coupled to the plurality of static transmitter units and to the one or more radio gateways; a mobile receiver unit configured to receive a positioning signal from any of the static transmitter units; and a location-determining server, wherein the scheduling server is configured to; use information representing a respective drift or offset of each of the respective clocks of the static transmitter units to generate the respective transmission schedules for the respective static transmitter units, each transmission schedule instructing a respective static transmitter unit to transmit the respective positioning signal at one or more scheduled times according to the clock of the static transmitter unit, by (i) determining information representing a device graph, the device graph comprising the one or more radio gateways and the static transmitter units, wherein a pair of devices is connected in the device graph when the scheduling server has received information representing the drift or offset of respective clocks of the pair of devices, satisfying one or more quality criteria, that enables the scheduling server to map time between the respective clocks of the pair of devices, and (ii) for each static transmitter unit, determining a respective shortest path through the device graph between a reference radio gateway of the one or more radio gateways and the static transmitter unit, and composing relative offset or drift information for devices along the respective shortest path in order to map a respective time or time period from the clock of the reference radio gateway to the clock of the respective static transmitter unit; and send the respective transmission schedules to the respective static transmitters units; wherein the mobile receiver unit is configured to send information derived from a positioning signal, received from any of the static transmitter units, to the location-determining server, and wherein the location-determining server is configured to use the information sent by the mobile receiver unit to determine the location of the mobile receiver unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of determining a location of a mobile receiver unit using a plurality of static transmitter units, each comprising a respective clock, using one or more radio gateways for communicating with the static transmitter units by radio, each radio gateway comprising a respective clock, the method comprising:
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a scheduling server using information representative of a respective drift or offset of each of the respective clocks of the static transmitter units to generate the respective transmission schedules for the respective static transmitter units, each transmission schedule instructing a respective static transmitter unit to transmit the respective positioning signal at one or more scheduled times according to the clock of the respective static transmitter unit, by (i) determining information representing a device graph, the device graph comprising the one or more radio gateways and the static transmitter units, wherein a pair of devices is connected in the device graph when the scheduling server has received information representing the drift or offset of respective clocks of the pair of devices, satisfying one or more quality criteria, that enables the scheduling server to map time between the respective clocks of the pair of devices, and (ii) for each static transmitter unit, determining a respective shortest path through the device graph between a reference radio gateway of the one or more radio gateways and the static transmitter unit, and composing relative offset or drift information for devices along the respective shortest path in order to map a respective time or time period from the clock of the reference radio gateway to the clock of the respective static transmitter unit; sending the respective transmission schedules to the respective static transmitters units; each of the static transmitters units using its clock to transmit a respective positioning signal according to the respective transmission schedule for the static transmitter unit; receiving one of the positioning signals at the mobile receiver unit; and using information derived from the received positioning signal to determine the location of the mobile receiver unit.
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26. A scheduling server for use in a system for determining a location of a mobile receiver unit, the system comprising one or more radio gateways, each comprising a respective clock, and a plurality of static transmitter units, each comprising a respective clock and being configured to use the respective clock to transmit a positioning signal according to a respective transmission schedule, wherein the scheduling server is configured to:
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use information representative of a respective drift or offset of each of the respective clocks of the static transmitter units to generate the respective transmission schedules for the respective static transmitter units, each transmission schedule instructing a respective static transmitter unit to transmit the respective positioning signal at one or more scheduled times according to the respective clock of the static transmitter unit, by (i) determining information representing a device graph, the device graph comprising the one or more radio gateways and the static transmitter units, wherein a pair of devices is connected in the device graph when the scheduling server has received information representing the drift or offset of respective clocks of the pair of devices, satisfying one or more quality criteria, that enables the scheduling server to map time between the respective clocks of the pair of devices, and (ii) for each static transmitter unit, determining a respective shortest path through the device graph between a reference radio gateway of the one or more radio gateways and the static transmitter unit, and composing relative offset or drift information for devices along the respective shortest path in order to map a respective time or time period from the clock of the reference radio gateway to the clock of the respective static transmitter unit; send the respective transmission schedules to the respective static transmitters units; and receive information, from the mobile receiver unit, derived from a positioning signal received by the mobile receiver unit from one of the static transmitter units, and to use the information to determine the location of the mobile receiver unit.
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27. A system for determining a location of a mobile receiver unit, the system comprising:
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a plurality of static transmitter units, each comprising a respective radio transmitter and a respective clock, and being configured to use the respective clock to transmit a respective positioning signal according to a respective transmission schedule; one or more radio gateways for communicating with the static transmitter units by radio, each radio gateway comprising a respective clock; a scheduling server, communicatively coupled to the plurality of static transmitter units and to the one or more radio gateways; and a mobile receiver unit configured to receive a positioning signal from any of the static transmitter units, wherein the scheduling server is configured to; use information representing a respective drift or offset of each of the respective clocks of the static transmitter units to generate the respective transmission schedules for the respective static transmitter units, each transmission schedule instructing a respective static transmitter unit to transmit the respective positioning signal at one or more scheduled times according to the respective clock of the static transmitter unit, by (i) determining information representing a device graph, the device graph comprising the one or more radio gateways and the static transmitter units, wherein a pair of devices is connected in the device graph when the scheduling server has received information representing the drift or offset of respective clocks of the pair of devices, satisfying one or more quality criteria, that enables the scheduling server to map time between the respective clocks of the pair of devices, and (ii) for each static transmitter unit, determining a respective shortest path through the device graph between a reference radio gateway of the one or more radio gateways and the static transmitter unit, and composing relative offset or drift information for devices along the respective shortest path in order to map a respective time or time period from the clock of the reference radio gateway to the clock of the respective static transmitter unit; and send the respective transmission schedules to the respective static transmitters units, wherein the mobile receiver unit is configured to derive information from a positioning signal, received from any of the static transmitter units, and to use the information to determine the location of the mobile receiver unit.
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Specification