摘要:
Communication devices and communication network techniques are employed to meet safety-critical, operational requirements for train location and control in railroad and public transit applications. On-board and trackside communication radios participate in a synchronous, time-slotted communication network, providing contentionless and highly responsive access to all participants. Encrypted, validated, and error protected communication links provide reliable and redundant transfer of information among the train, trackside, and control station radios. Spread spectrum communication techniques enable range measurements between all participants. These wireless communication links relay train range measurements to control or processing stations and relay control information (principally speed commands) from the processing stations to the trains. High resolution position location is determined along elevated, at-grade, and in-tunnel tracks using wireless methods and sparse device placement.
摘要:
An apparatus and method for providing an aircraft-based wireless communications service is disclosed. An exemplary system includes a plurality of aircraft each including on-board equipment for supporting wireless communications with one or more dual mode handsets and for exchanging wireless communication traffic and control information. One or more ground stations communicate with the plurality of commercial aircraft using feeder communications links exchanging the wireless communication traffic and control information and providing interfaces with a terrestrial telecommunications infrastructure. A control center manages the one or more ground stations and the on-board equipment of the commercial aircraft and dynamically assigns resources to the on-board equipment of the plurality of aircraft using an overlapped set of coverage patterns.
摘要:
A wireless communications system and method provides wireless communications service for user equipment on board an aircraft. The aircraft includes on-board system equipment for supporting the wireless communications service with on-board user equipment. One or more ground stations are used for communicating with the aircraft using a plurality of feeder links for exchanging the wireless communications service's traffic and control information with the on-board system equipment, and for providing interfaces with a terrestrial telecommunications infrastructure. A mobile switching center manages the ground stations and the on-board system equipment of the aircraft, wherein the mobile switching center includes at least one platform visitor location register (VLR) associated with each aircraft to ensure proper registration and tracking of the user equipment used on board the aircraft.
摘要:
A wireless communications system and method provides wireless communications service for user equipment on board an aircraft. The aircraft includes on-board system equipment for supporting the wireless communications service with on-board user equipment. One or more ground stations are used for communicating with the aircraft using a plurality of feeder links for exchanging the wireless communications service's traffic and control information with the on-board system equipment, and for providing interfaces with a terrestrial telecommunications infrastructure. The on-board system equipment transitions connections by the on-board user equipment between the feeder links.
摘要:
A method and apparatus for efficiently obtaining improved coverage in augmenting GPS position location with differential GPS integrity and correction messages using existing satellite systems, planned satellite systems, or a combination of both to broadcast these integrity and correction messages without requiring dedicated satellite resources. At least one existing satellite system offers full global coverage whereas the conventional approach of disseminating these integrity and correction messages using geostationary satellites necessarily omits Polar Regions. This existing satellite system also provides redundant coverage globally whereas the conventional approach using geostationary satellites must increase the number of geostationary satellites in direct proportion to the level of redundancy desired. At least one other existing satellite-based system offers higher availability (i.e., more geographically complete) coverage with these integrity and correction message by also employing ground-based transmitters to gain three way redundant coverage. Using existing or planned satellite systems to broadcast differential GPS integrity and correction messages also eliminates the expense and delays associated with building and launching either dedicated geostationary satellites or dedicated satellite payloads on host satellites. Using available satellite resources also enables cost efficient customization of disseminated integrity and correction messages. The apparatus comprises a set of ground reference stations with individual assigned geographic spaces, a master station that gathers integrity and correction messages from these ground reference stations and transmits them to a satellite-based system or systems that broadcast integrity and correction messages, possibly customized, and users with equipment capable of receiving signals from the satellite system.
摘要:
A method and apparatus for determining and tracking the geodetic position of a mobile platform (i.e., aircraft). The apparatus comprises a ground controller assigned to a geographic space (i.e., an airspace) and at least one mobile platform (i.e., aircraft) communicating with the ground controller on a bi-directional communications link, wherein each mobile platform (i.e., aircraft) transmits a mobile platform (i.e., an aircraft) signal comprising at least a time of transmission of the mobile platform (i.e., aircraft) signal; the ground controller transmits a ground signal comprising at least a time of transmission of the ground signal and a location of the ground controller; each mobile platform (i.e., aircraft) performs time-of-arrival (TOA) measurements on the mobile platform (i.e., aircraft) signals received by that mobile platform (i.e., aircraft) and also performs TOA measurements on the ground signal received by that mobile platform (i.e., aircraft); the ground controller performs TOA measurements on each of the mobile platform (i.e., aircraft) signals received by the ground controller; each mobile platform (i.e., aircraft) determines a range (i.e., an air range) between that mobile platform (i.e., aircraft) and other mobile platforms (i.e., aircraft) and a ground range between that mobile platform (i.e., aircraft) and the ground controller; each mobile platform (i.e., aircraft) determines its geodetic position based on at least the ranges (i.e., air ranges) and ground range for that mobile platform (i.e., aircraft) and the position of the ground controller.