Heterogeneous and small cell networks: Part 2 [Guest Editorial]

e are back this month with a sequel to our May 2013 Feature Topic on heterogeneous and small cell networks (Het- SNets). In this follow-up, we have six more articles that address cognitive radio, moving cells, WiFi offloading, and energy efficiency aspects of HetSNets. The first article, by Song et al., provides a holistic view of hyper-dense HetSNet deployments by comparing massive antenna and dense deployment, and providing some enabling technologies that can handle the technical challenges in HetSNets.