Teledesic LLC

Shiva S Sarrafan

Sami M Hinedi

Mark Alan Sturza

Farzad Ghazvinian

Biren N Shah

A system for acquiring the beacon of a satellite and synchronizing data transmission between the satellite and a ground terminal is disclosed. The ground terminal conducts a search for a satellite to be acquired. The search may be based on previously developed information from which the location of the satellite can be predicted and, thus, limited to a small area of the sky, or cover a large area of the sky in accordance with a search routine. After the beacon of a satellite is acquired, the geographic area served by the satellite is determined. If the satellite does not serve the cell within which the ground terminal is located, a further satellite search is conducted, which may be based in part on information contained in the beacon of the acquired satellite. After the satellite serving the cell containing the ground terminal is acquired, a test is made to determine how long the satellite will continue to cover the cell. If the time period is short, communication waits until the next satellite to cover the cell is acquired. If the time period is long, communication is allowed to begin. The beacon is also used by the ground terminal to: (i) accurately time uplink data transmissions; (ii) estimate uplink Doppler, Doppler rate, and Doppler rate derivative and use this information to pre-compensate the carrier frequency of the uplink data transmissions for Doppler variations; and (iii) estimate the carrier frequency of downlink data transmission(s) by continuously tracking the beacon carrier frequency and scaling the result by a suitable scaling factor.

Low-earth orbit satellite acquisition and synchronization system using a

A method for reducing co-channel or cross-channel interference between cells of a cell network in a frequency division multiple access (FDMA) communications system is disclosed. The method comprises the steps of: dividing the cells of the cell network into a first subset of cells and a second subset of cells; dividing the available bandwidth for the system into a first set of sub-bands, each of which has a sub-band bandwidth and a second set of sub-bands, each of which has a sub-band bandwidth, the second set of sub-bands being offset in frequency from the first set of sub-bands; assigning the first set of sub-bands to the first subset of cells and the second set of sub-bands to the second subset of cells.

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Issaquah, WA, United States of America

Shiva S Sarrafan