Cellular mobile communication networks are experiencing an important evolution with the emerging deployment of 5G networks and the successive decline in the use of previous generations in the years to come. In parallel, policies promoting ecological transition are gaining social impact and economic interest and this seems to be the trend in the near future. In the telecommunications market, the shift between two dominant generations could be an important opportunity to introduce renewable energy sources to green the sector, reducing the carbon footprint of the world-wide extended activity. This work analyses the current situation and provides an insight into the possibilities to incorporate renewable energy supplies, specifically photovoltaics (as it seems to be the most promising among clean electric sources), perhaps combined with small wind turbines in off-grid systems. Paper also compares the characteristics of standard facilities in Spain and Poland, two different European countries in terms of weather and insolation hours.

Utilization of drones is going to become predominated in cellular networks as aerial base stations in order to temporary cover areas where stationary base stations cannot serve the users. Detecting optimal location and efficient number of drone-Base Stations (DBSs) are the targets we tackle in this paper. Toward this goal, we first model the problem using mixed integer non-linear programming. The output of the proposed method is the number and the optimal location of DBSs in a two-dimension area, and the object is to maximize the number of covered users. In the second step, since the proposed method is not solvable using conventional methods, we use a proposed method to solve the optimization problem. Simulation results illustrate that the proposed method has achieved its goals.