Table 2. Performance comparison of different point-pair selection schemes

Orbit type & selection scheme		Relative variance	Mean (km)	Computation time (s)
MEO	2-group scheme	5.79 × 10–6	2.573 × 107	0.58
	6-group scheme	1.17 × 10–6	2.572 × 107	1.72
	Full combination scheme	2.07× 10–7	2.573 × 107	275.30
LEO	2-group scheme	8.34 × 10–8	7.798 × 106	0.11
	6-group scheme	1.12 × 10–8	7.797 × 106	0.29
	Full combination scheme	1.36 × 10–9	7.798 × 106	56.40
GEO	2-group scheme	1.46 × 10–6	4.215 × 107	0.52
	6-group scheme	2.75 × 10–7	4.215 × 107	1.62
	Full combination scheme	2.40 × 10–8	4.216 × 107	310.40

MEO, Medium Earth Orbit; LEO, Low Earth Orbit; GEO, Geostationary Earth Orbit.