A Frequency-Routed Satellite System Concept using Multiple Orthogonally-Polarized Beams for Frequency Reuse

The paper outlines the design concepts of a multibeam frequency-division multiplexed satelite system which is accessed by many moderatelysized earth stations. Each satellite beam uses either horizontal or vertical polarization for better interbeam isolation and greater frequency reuse. Instead of treating the usual model of uniformly positioned equal-traffic centers covered by regularly spaced spot beams, the paper analyzes a realistic non-uniform traffic distribution. The topics discussed include the optimum beam size; beam isolation; a connected graph presentation of the multiple beams; orthogonal polarization assignment to beams; the concept of beam groups, which yields a simple transponder design; and the establishment of a frequency plan which provides interference-free band assignments. An example that illustrates the concepts involves 20 closely spaced traffic centers which are covered with 10 spot beams of horizontal and vertical polarization; a relatively simple transponder and careful frequency assignment yield a 2.15 times reuse of the bandwidth apportionment. A more substantial bandwidth increase will be obtained in situations that employ a larger number of beams.