1. Alsharif, M. H., & Nordin, R. (2017). Evolution towards fifth generation (5 g) wireless networks: current trends and challenges in the deployment of millimetre waves, massive MIMO, and small cells. Telecommunication System, 64(4), 617–637.
2. European Commission, Energy Efficiency. Saving energy, saving money, 2016.
3. Filippini, I., Redondi, A. E., & Capone, A. (2017). Beyond cellular green generation: potential and challenges of network separation. Hindawi Mobile Information System, 17, 7149643.
4. Oikonomakou, M., Antonopoulos, A., Alonso, L., & Verikoukis, C. (2017). Evaluating cost allocation imposed by cooperative switching off in multi operator shared hetnets. IEEE Transaction Vehicular Technology, 66(12), 11352–11365.
5. Han, Q., Yang, B., Miao, G., Chen, C., Wang, X., & Guan, X. (2017). Backhaul-Aware user association and resource allocation for energy-Constrained hetnets. IEEE Transaction Vehicular Technology, 66(1), 580–593.