Telecommunications networks are subject to continuous improvement and enhancement processes. Every new iteration brings its set of challenges and limitations. In fact, the exponential growth in telecommunication devices, from base stations to user equipment lead to serious energy efficiency issues. Along with the privacy threats, especially for wireless networks as the channels used by operators can also be used by any eavesdropper. Spectrum usage optimization is also a challenge due to the fact that the available spectrum in wireless communications systems has been a very rare resource because of the increasing demand. Emerging networks, such as femtocells, suffer also from the previously mentioned challenges. The current work focuses on proposing several solutions to the previously cited challenges: energy efficiency, spectrum sharing and security.