Future mobile networks (6G) will be the convergence of past features, such as network densification, high throughput, high reliability, and low energy consumption, and will offer new services, such as smart wearables, autonomous vehicles and 3D mapping. In this context, the planning process involves a number of parameters. Among them, we can mention the increase in service requests, the compatibility of heterogeneous systems, the advent of new technologies, as well as the flexible quality of service. As a result, we propose approaches that optimize the overall infrastructure costs, by identifying the interactions between the parameters and taking into account the network capacity, as well as the energy consumption. Such proposed approaches guarantee that future mobile networks will be deployed and operate in a sustainable way.