The purpose of this work is to optimise the necessary computation time for the coverage zone prediction. Several approaches exist to reduce the calculation time; they consist in simplifying the complexity of the used propagation model. Here, our method is different but complementary of the previous approaches. Indeed, it is independent of the propagation model and tries to reduce the number of application points of the considered model for the coverage prediction. Thus, the performances of our optimised method in term of accuracy and computation time is presented in this article