Alternative concepts of antenna deployment and cell layout in mobile communications

Cellular communication systems have traditionally been designed according to the paradigm that base stations serve independent sectors for which inter-sector interference should be minimized. Further, multiple base stations serving multiple sectors are traditionally grouped into a minimum number of sites, in order to reuse infrastructure for cooling, battery backup etc. and minimize site rental cost. Considering the current evolution of mobile communications, however, both the paradigm of avoiding interference and that of minimizing the number of sites may have to be revisited. For example, multi-cell transmission and reception schemes (i.e. such as Multiflow in HSPA or Coordinated Multi-Point (CoMP) in LTE-Advanced) provide the highest gains where cell overlap is maximized. Further, the development of active radio heads with significantly reduced cost, form factor, cooling requirements and simplified site acquisition may completely change the way in which cellular systems should be deployed. In this paper, we compare classical to alternative deployment concepts and evaluate these according to the achievable spectral efficiency per area, taking into consideration different assumptions regarding cost evolution. It is shown that especially rings of inward-pointing sectors can be an interesting alternative deployment strategy in the context of sector cooperation.