Low cost wide area network for data communication using outbound message specifying inbound message time and frequency
First Claim
1. A two-way wireless data communication system comprising:
- an outbound messaging sub-system for sending outbound messages;
an inbound messaging sub-system consisting of a network of at least two radio frequency base stations for receiving inbound messages, the radio frequency base stations also continuously sampling, at their respective locations, a set of frequency channels in an inbound radio frequency band, to determine an observed frequency availability level for the set of frequencies for each base station;
at least one remote field unit having an outbound message receiver and a tunable inbound message transmitter; and
a central control unit, wherein the central control unit uses the outbound messaging sub-system as an outbound link to send an outbound message to the remote field unit, and uses the inbound messaging sub-system as an inbound link to receive an inbound message from the field unit, and wherein the outbound message comprises a time data field and a frequency data field indicating, respectively, an inbound message time and an inbound message carrier frequency at which the field unit is to send an inbound message in response to the outbound message, and wherein the central control unit receives reports of the observed frequency availability levels from the network of radio base stations, and the central control unit selects the time data field and frequency data field such that the inbound message will be received by one or more of the base stations in the inbound messaging sub-system without interference from another communication system.
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Accused Products
Abstract
A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and frequency at which the RBSs can expect to receive data from the field units. A network hub or message operations center (MOC) coordinates the operation of the paging systems and RBSs from a central location. For example, the MOC determines an available HF frequency and time for a particular field unit to transmit, and then issues the request for data to the field unit using the existing paging network infrastructure. The field units make use of paging receivers, and an HF transmitter to report remote data such as a geoposition or other sensor data when requested to do so.
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Citations
26 Claims
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1. A two-way wireless data communication system comprising:
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an outbound messaging sub-system for sending outbound messages; an inbound messaging sub-system consisting of a network of at least two radio frequency base stations for receiving inbound messages, the radio frequency base stations also continuously sampling, at their respective locations, a set of frequency channels in an inbound radio frequency band, to determine an observed frequency availability level for the set of frequencies for each base station; at least one remote field unit having an outbound message receiver and a tunable inbound message transmitter; and a central control unit, wherein the central control unit uses the outbound messaging sub-system as an outbound link to send an outbound message to the remote field unit, and uses the inbound messaging sub-system as an inbound link to receive an inbound message from the field unit, and wherein the outbound message comprises a time data field and a frequency data field indicating, respectively, an inbound message time and an inbound message carrier frequency at which the field unit is to send an inbound message in response to the outbound message, and wherein the central control unit receives reports of the observed frequency availability levels from the network of radio base stations, and the central control unit selects the time data field and frequency data field such that the inbound message will be received by one or more of the base stations in the inbound messaging sub-system without interference from another communication system. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A two-way wireless data communication system comprising:
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a paging sub-system for sending outbound request messages to a remote field unit; an inbound messaging sub-system consisting of at least one radio base station for receiving inbound messages from the remote field unit, the at least one radio base station also continuously sampling, at its respective location, a set of frequency channels in an inbound radio frequency band, to determine an observed frequency availability level for the set of frequencies for the base station; at least one remote field unit having an outbound message receiver and a tunable inbound message transmitter; and a central control unit, wherein the central control unit uses the paging system as an outbound link to send an outbound message to the remote field unit, and uses the inbound messaging sub-system as an inbound link to receive an inbound message from the field unit, and wherein the outbound message comprises a time data field and a frequency data field indicating, respectively, an inbound message time and an inbound message carrier frequency at which the field unit is to send an inbound message in response to the outbound message, and wherein the central control unit receives reports of the observed frequency availability levels from the network of radio base stations, and the central control unit selects the time data field and frequency data field such that the inbound message will be received by one or more of the base stations in the inbound messaging sub-system without interference from another communication system. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of operating a communications system to provide ubiquitous wireless data communication services between a message operations center (MOC) and a plurality of remote field units, by using a network of widely distributed radio base station (RBS) sites and multiple paging systems, the method comprising the steps of:
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A. at a customer calling station, initiating a request to the MOC to communicate with a particular remote field unit, such as a request for the field unit to determine and report its location; B. at the MOC site, i. polling the RBS sites to determine a radio frequency which is presently suitable for the field unit to send an inbound message back to one or more of the RBS sites; ii. determining an available frequency and a time for the field unit response; iii. formatting the time and frequency for the field unit response into an outbound page message; iv. forwarding the page message to at least one of the paging systems; C. in at least one of the paging system sites, communicating the page message to the field units over the paging system; D. at the selected field unit, i. receiving the page message; ii. formulating a response to the page message by reading data available locally to the field unit; iii. formulating a response as an inbound message back to the radio base stations; iv. encoding the response in the form of a short duration burst message, to minimize the probability of interfering with existing broadcast or other communications at frequencies near the selected frequency; v. at the indicated carrier frequency and time, transmitting the inbound message over the air; E. at the RBS site, i. receiving the inbound message from the field unit over the air; and ii. forwarding the inbound message back to the MOC; F. at the MOC site, forwarding the inbound message back to the customer calling station; and G. at the calling station, receiving inbound message. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification