With the proliferation of connected devices and emerging data-hungry applications, the volume of mobile data traffic is predicted to have a 1000-fold growth by the year 2020. To address the challenge of this data explosion, industry and academia have initiated research and development of 5G wireless networks, which are envisaged to cater to the massive data traffic volume, while providing ubiquitous connectivity and supporting diverse applications with different quality of service (QoS) requirements. To support the expected massive growth of mobile data, a large number of small cells are expected to be deployed indoors and outdoors, giving rise to heterogeneous networks (HetNets), which are considered to be the key path toward 5G. With such large-scale HetNets, network operators face many serious challenges in terms of operation and management, cost-effective small cell deployment, and intercell interference mitigation. To deal with those issues, a cloud based platform is introduced, aiming to simplify the deployment, operation and management, and facilitate round-the-clock optimization of the network, to pave the way for the development of 5G. Two case studies are provided to illustrate the benefits of the cloud based architecture. Finally, the related standardization activities are provided and some research topics essential for a successful development of 5G are discussed.