We describe a new technique for simulations of large communication networks. This technique is based on a new approach for communication networks modeling by means of point processes and stochastic geometry tools. Simulator ARC developed by the authors and described in the paper uses recent effective geometrical algorithms for computing the topology of the system model. New algorithms based on stochastic gradient technique and implemented in the simulator, allow evaluation of certain performance characteristics of the system and can be used for optimization of the system parameters. We analyze the used estimator and give its asymptotic variance.