As the rapid growth of wireless traffic demands, the current wireless technology will be bounded in the next 10 years. To struggle for the high network capacity demands provoked by the explosion of current services, significant improvement to wireless access techniques have been made. Thus, it becomes complicated to design future 5G communication infrastructures while taking advantage of novel spectrum/radio technologies. Currently, mobile operators have been deploying heterogeneous networks to boost network capacity and coverage. Furthermore, in order to achieve better spectral efficiency, potential technologies for reconfigurable networks have been investigated, such as software-defined radio (SDR), cognitive radio (CR), and cognitive networks (CNs). However, those new characteristics, as well as novel spectral efficiency technologies for 5G, need to be further studied. In particular, how to apply spectral efficiency technologies on the newly developed network architectures should be actively addressed and discussed.