Positioning system using low earth orbit constellations

A scheme of designing low Earth orbit satellite positioning system is proposed. An example low Earth orbit satellite constellation providing the positioning function over certain region is presented. The proposed constellation consists of 75 satellites with four different inclinations. The satellites are in the orbit of height of about 800 Km. It can provide the positioning function over the region with radius of about 3000 Km center at the chosen site with longitude of 122 degrees E and latitude of 25 degrees N. The construction of the constellation is based on the requirement of good values of the Dilution of Precision over the specific region at same time. Also the study of the relativistic effects of the system shows that the requirement of keeping the orbit of the low Earth orbit satellite positioning system circle is less stringent than the GPS's.