Qualcomm Incorporated

Sridhar Vembu

Nadav Levanon

Edward B Victor

A system and method for unambiguously 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 two satellites with known positions and known velocities, 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, a range difference parameter, and either or both of a range-rate parameter and a range-rate difference parameter. A range parameter represents a distance between one of the satellites and the user terminal. A range difference parameter represents the difference between (1) the distance between a first one of the satellites and the user terminal and (2) the distance between a second one of the satellites and the user terminal. A range-rate parameter represents a relative radial velocity between one of the satellites and the user terminal. A range-rate difference parameter represents the difference between (a) a relative radial velocity between a first one of the satellites and the user terminal and (b) a relative radial velocity between a second one of the satellites and the user terminal. The position of the user terminal on the Earth's surface is then determined based on the known positions and known velocities of the satellites, the range parameter, the range difference parameter, and either or both of the range-rate parameter and the range-rate difference parameter.

Unambiguous position determination using two low-earth orbit satellites

A system and method for optimizing power control provides dynamic adjustment of a power-control threshold thereby allowing transmitter power to be reduced when signal quality is high. In a communication system having at least one mode for controlling the power of a transmitter in the communication system, the threshold level of the system is optimized by determining performance of the communication system based on a predetermined metric such as the system error rate, for example. Additionally, the power of the transmitter or transmitted signal in relation to the threshold of the communication system is determined. The threshold of the communication system is adjusted based on the performance of the communication system and the power of the transmitter in relation to the threshold.

System and method for optimized power control

A system and method for switching between power control modes is implemented in a communication system having two or more power control modes for providing a power increase for a transmitted signal. The system and method determine whether performance of the communication system is within nominal bounds. If the performance of the communication system is within nominal bounds, a first mode of power control is selected for controlling transmitter power. If the performance of the communication system is not within the nominal bounds, a second mode of power control for controlling a transmitter is selected.

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San Jose, CA, United States of America

Sridhar Vembu