Optimal mobile radio channel assignment using energy minimising and geometrical constraints

The growth in the number of mobile users is stimulating interest in the optimum design of mobile communication networks. In particular, network operators are required to satisfy a prescribed traffic demand with a limited spectrum allocation. This implies the allocation of channels to base stations subject to a frequency re-use regime which minimises co-channel and adjacent channel interference. This optimisation problem can be shown to be NP complete, and thus the time taken to obtain a solution scales exponentially with the size of the problem. Therefore, for practical channel assignment problems it is not feasible to use deterministic methods to obtain a solution. This paper extends the technique published by Lochtie and Mehler (see IEE Proceedings Communications, vol.142, no.3, 1995) to enable inhomogeneous interference constraints to be enforced. Practical results are presented for a typical channel assignment problem in southern England, and the method is compared which the homogeneous approach.