This paper

from the characteristics of the mobile satellite ground track

discusses a design method of mobile satellite constellations with common ground track

and also uses the method on the China area design by computer simulation and specialized satellite communication tool. By choosing the satellite orbit period as one fourth of the sidereal day

the eccentricity as 0. 158

the orbital plane inclination as 63 .4 degrees

ouly four satellites with common ground track can cover China mainland almost almos seamlessly

while the average elevation angle is greater than 50 degrees.