Over the past few decades, mobile and wireless communications as well as Internet have been the most profound and important technologies in information technology that are rapidly growing and continuously changing human life. Despite the tremendous potentials of wireless networks, several significant research challenges remain to be addressed before widespread deployment of wireless networks, including isolation, control signaling, resource discovery and allocation, mobility management, network management and operation, and security as well as non-technical issues such as governance regulations, etc. In recent years, the demands of mobile data keep thriving, meanwhile, the smart phone and mobile applications become increasingly powerful and varied. These lead to a sporadic opportunity to combine both mobile communications and Internet, i.e. mobile Internet. In this paper, we present a critical review of New Developments and Research Challenges for 5G Wireless Systems and Networks. The paper includes discussions on technology development approach toward 5G, some supporting technologies, technology components and then research challenges in 5G wireless systems.