Self-Organizing Context-Aware small cell networks: Challenges and future opportunities

Introduction The recent proliferation of bandwidth-intensive wireless applications such as social networking, web browsing, gaming, and video conferencing is driving wireless operators to continuously upgrade their infrastructure. For instance, the increasing number of wireless users combined with the limited resources of conventional cellular networks imply that novel cost-effective wireless networking solutions are needed so as to satisfy the thriving needs for better quality of service (QoS) and high wireless data rates. To better serve the wireless users’ needs, it has been recently proposed to overlay, on top of existing cellular networks, small cells which can be used indoors (e.g., in homes and businesses) and outdoors (e.g., in low coverage areas) [3, 11, 18]. These small cells are serviced by low-cost, low-power, small base stations. Types of small cells include femtocells, picocells, metrocells, and microcells – broadly increasing in size from femtocells (the smallest) to microcells (the largest). Small cell base stations (SCBSs) can operate over the licensed spectrum and coexist with the main macrocellular network. Unlike macrocell base stations (MBSs), whose deployment is planned by the network operator, the deployment of SCBSs can either be planned, by the operator, or unplanned (e.g., femtocell base stations (FBSs) installed at home by end users) [14, 20, 21, 36, 37]. Moreover, the deployment of small cell wireless networks introduces numerous technical challenges at different levels such as self-organization and self-adaptation, interference management (cross-tier, i.e., between macro-cells and small cells, as well as intra-tier, i.e., between small cells), security and privacy, and energy-efficiency and others [1, 2, 17, 24, 26, 30–33, 47–49]. Various economic aspects of small cell networks have also drawn attention in the wireless communications community [12, 15, 57].