Abstract
In dense indoor areas, high numbers of people use their smartphones and tablets to share or download pictures, videos, or data. The heterogeneous network (HetNet) solves the problems caused by the explosion of data generated by smartphones and tablets. Heterogeneous networks use a mix of Relay, Femtocell, Pico, and Macro base stations to improve spectral efficiency per unit area. Operators wish to know how to upgrade existing networks and how to design new ones. This subject has become hot in the industry. In this paper, we presented the architecture of heterogeneous networks. The parameters affecting the heterogeneous networks topology plan are discussed. Moreover, a comparison of existing solutions that consider the problems of base station layout planning is presented. Finally, a road map is given to point out to the main future directions of researches on the topological design of dense area heterogeneous mobile networks.