assume that the coverage area of cell have radious =R
& the distance between site to site is= D
& the number of sites youcan put on all your freq=(reuse pattern)
Reuse pattern may be 4 sites, 3, or 7 sites as you like.so the num of site in reuse pattern is K or (reuse factor). which allow you to reuse the freqs in another pattern. so you plan small reuse or large.
D= squ Root(3KR).