Abstract: The regional navigation constellation can provide the navigation ability for the users of the targeted area with the balanced cost and efficiency, and the geosynchronous orbits are some of the important orbit types to construct non-polar regional navigation constellation. A configuration method was proposed for regional navigation constellation based on GEOs (geosynchronous orbits) and IGSOs (inclined geosynchronous orbits). Firstly, a set of SSP (sub-satellite point) involved design parameters were presented and depicted especially for the symmetric constellation. And the long-term perturbations due to the earth's oblateness were induced to recalculate the mean orbital elements of the GEOs and IGSOs and propagate their orbits. Then the statistical GDOP (geometric dilution precision) of the grid points of the specific navigation service area was used as the objective function for the DE (differential evolution) optimization algorithm. Finally, taking the Indian constellation of IRNSS as an example, the presented design and optimization algorithm was verified by the constellation simulation, and various configurations and orbit types of IRNSS constellation were discussed in detail. The results show that for India and surrounding region, the 7-satellite constellation can best consider the navigation performance and construction cost; the elliptical orbit is unable to take into account the navigation performance of the northern and southern hemispheres, which is difficult to expand to global navigation constellation. This method can improve the global optimization efficiency of GEO / IGSO hybrid regional navigation constellation, and provide the number of satellites and configuration design quickly for the subsequent asymmetric constellation. 

Key words: regional navigation constellation, GEO/ IGSO satellite, differential evolution algorithm, constellation design optimization