Hughes Electronics Corporation

The Boeing Company

Jeffrey E Outwater

James D Thompson

Mohammad Soleimani

William F Courtney

Kuang-Yu Li

Tracking of collocated satellites is accomplished by providing a single tracking antenna having a tracking feed and combiner which receives a first satellite signal. A first pointing error signal is extracted from the tracking feed based on the first satellite signal and the antenna is steered to a pointing angle to minimize the first pointing error signal. A second satellite signal is received and a second pointing error signal is extracted from the tracking feed based on the second satellite signal. An offset angle for the second satellite is then calculated from the second pointing error signal relative to the pointing angle of the antenna. Orbit estimation and can then be accomplished for the second satellite based on the offset angle directly or by conversion to an absolute angle.

Multitracking of collocated satellites

An earth orbiting satellite communicates with ground-based communication terminals via a limited number of frequency channels. To maximize the amount of concurrent communication that can be accommodated, the satellite's effective service area is partitioned into cells. The position of each cell relative to nearby cells is established in support of a scheme to maximize channel reutilization. Based on knowledge of communication demand and inter-cell interference constraints, all available channels are associated with particular groups of cells having a common relative position. This establishes a preference for assigning channels to particular cell groups. As communication demand in the cells fluctuates and additional communication channels are required, the channel assignment preferences are consulted to determine which channels to assign to the requesting cells.

Cellular communication system employing dynamic preferential channel allocation

A mobile, satellite-based communication system includes a defined signaling arrangement developed from an analysis of factors including movement of the mobile terminals, movement of the satellite, beam discrepancies and duration of the call to the mobile terminal to set up a frame assignment plan for time division multiple access (TDMA) carriers and identifying permissible frame offset which can be accommodated throughout the entire transmission. As a result, timing and frequency references from a mobile to mobile command (MMC) may be provided from a reference source along with receive and transmit data communications without losing the command signals or the communication information and providing highly efficient use of each carriers time slots for receiving transmitting communication signals. Similarly, the signaling arrangement permits an efficient frame structure and a time slot assignment plan that does not require enhanced equipment at the mobile terminal. Moreover, the signaling frame assignment is applicable to multibeam satellite-based mobile communication systems for use with communications between mobile terminals and gateways as well as between mobile terminals.

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Agoura Hills, CA, United States of America

Jeffrey E Outwater