Advances and Challenges toward a Scalable Cloud Radio Access Network

With centralized processing, cooperative radio, real-time cloud computing, and clean infrastructure, C-RAN is a "future-proof" solution to sustain the mobile data explosion in future wireless networks. The technology holds great potential in enhancing LTE with the necessary capability to accommodate the unprecedented traffic volume that today's wireless cellular system is facing. However, the high density of RRHs in C-RANs leads to severe scalability issues in terms of computational and implementation complexities. This article discusses the challenges and recent developments in the technologies that potentially address the scalability issues of C-RANs. In particular, we focus on the collaborative signal processing, resource management, and green architecture of C-RAN systems. This article is a humble attempt to draw the attention of the research community to the following important question: how to leverage the revolutionary architecture of C-RAN to attain unprecedented system capacity at an affordable cost and complexity.