초록 ▼

A system and method for determining the position of a user terminal (for example, a mobile wireless telephone) in a low-Earth orbit satellite communications system. The system includes a user terminal, at least one satellite with a known position and velocity, and a gateway (that is, a terrestrial b

A system and method for determining the position of a user terminal (for example, a mobile wireless telephone) in a low-Earth orbit satellite communications system. The system includes a user terminal, at least one satellite with a known position and velocity, and a gateway (that is, a terrestrial base station) for communicating with the user terminal through the satellites. The method includes the steps of determining a range parameter and a range-rate parameter. A range parameter represents a distance between the satellite and the user terminal. A range-rate parameter represents a relative radial velocity between that satellite and the user terminal. The position of the user terminal on the Earth's surface is then determined based on the range parameter, the range-rate parameter, and the known position and velocity of the satellite.

대표청구항 ▼

[ What I claim as my invention is:] [1.] A position determining system for a satellite communications system, comprising:a user terminal;a satellite with a known position and a known velocity;a gateway for communicating with said user terminal through said satellite;range parameter determining means

[ What I claim as my invention is:] [1.] A position determining system for a satellite communications system, comprising:a user terminal;a satellite with a known position and a known velocity;a gateway for communicating with said user terminal through said satellite;range parameter determining means for determining a range parameter;range-rate parameter determining means for determining a range-rate parameter that represents frequency measurements of a first signal and a second signal;first frequency measuring means in said user terminal for measuring a frequency of said first signal, said first signal received from said gateway through said satellite;sending means in said user terminal for sending said frequency measurement of said first signal to said gateway;second frequency measuring means in said gateway for measuring a frequency of said second signal, said second signal received from said user terminal through said satellite; andposition determining means in said gateway for determining a position of said user terminal on the Earth's surface based on said known position and velocity of said satellite, said range parameter, and said range-rate parameter.