Geometrical Characteristics and SIR in Two Coexisting Cellular Radio Networks using the same Frequencies

The possibility of having two radio networks sharing a common set of frequencies is investigated for regular hexagonal cell layouts. While for a single network a hexagonal symmetry of the co-channel lattice is optimum, it turns out, that a monoclinic symmetry is attractive for coexisting networks. Characteristic distances of frequency patterns belonging to different symmetry classes are calculated. Based on the analysis of the influence of adjacent channel interferers and the calculation of SIR distributions in two symmetrical coexisting networks it is shown, that the outage probability can be reduced and smaller reuse factors are possible, if the proposed alternative patterns are used instead of those optimum for single networks.