Mobile data traffic is currently growing exponentially and these rapid increases have caused the backhaul data rate requirements to become the major bottleneck to reducing costs and raising revenue for operators. To address this problem, caching techniques have attracted significant attention since they can effectively reduce the backhaul traffic by eliminating duplicate data transmissions that carry popular content. In addition, other system performance metrics can also be improved though caching techniques, e.g., spectrum efficiency, energy efficiency, and transmission delay. In this paper, we provide a systematical review of the state-of-the-art caching techniques that were recently developed in different wireless communication networks, including cellular networks, heterogeneous networks (HetNets), device-to-device (D2D) networks, cloud-radio access networks (C-RANs), and fog-radio access networks (C-RANs). We discuss content placement, content delivery, and joint placement and delivery algorithms.We also compare the different proposed approaches in terms of different performance metrics, including throughput, backhaul cost, power consumption, and network delay. In addition, we summarize the main research achievements in different networks, and highlight some challenges and promising potential research topics.

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ObjectiveTo examine levels of support for comprehensive smoke-free policies in six large Chinese cities.MethodsData from Wave 1 of the International Tobacco Control (ITC) China Survey (April–August 2006) were analysed. The ITC China Survey employed a multistage sampling design in Beijing, Shenyang, Shanghai, Changsha, Guangzhou and Yinchuan (none of which has comprehensive smoke-free policies in place). Face-to-face interviews were conducted with 4815 smokers and 1270 non-smokers. Multivariate logistic regression models were used to identify factors associated with support for comprehensive smoke-free policies.ResultsAbout one in two Chinese urban smokers and four in five non-smokers believed that secondhand smoke (SHS) causes lung cancer. The majority of respondents supported comprehensive smoke-free policies in hospitals, schools and public transport vehicles while support for smoke-free workplaces, restaurants and bars was lower. Levels of support were generally comparable between smokers and non-smokers. Support for comprehensive smoke-free policies was positively associated with knowledge about the harm of SHS. Respondents who worked in a smoke-free worksite or who frequented smoke-free indoor entertainment places were more likely to support comprehensive smoking restriction in bars and restaurants.ConclusionConsiderable support for smoke-free policies exists in these six large cities in China. Greater public education about the dangers of SHS may further increase support. Experiencing the benefits of smoke-free indoor entertainment places and/or workplaces increases support for these policies and suggests that some initial smoke-free policy implementation may hasten the diffusion of these public health policies.

Wireless networks are undergoing a transition from connecting people to connecting things, which will allow human interaction with the physical world in a real-time fashion, e.g., tactile internet, industrial automation, self-driving vehicles, and remote surgery. Therefore, future wireless networks need to support real-time control since it is the essential function enabling such emerging applications. In this article, some fundamental design capabilities needed to realize real-time control in future wireless networks are discussed, with primary emphasis given to communication-control because both communication and control systems have strong dynamics and interdependencies, and they tightly interact with each other. A case study is provided to demonstrate the necessity of such co-design.

In real-time cyber physical systems, packetized predictive control (PPC) is an effective solution to conduct robust control over unreliable wireless links. However, the conventional PPC design considers the control and communication systems independently, which does not guarantee the minimum wireless resource consumption. In this paper, we investigate the tight interaction between control and communication. In particular, we propose a communication-control co-design method to optimize the predication length of PPC, then the system can achieve the minimum wireless resource consumption. Our results demonstrate the advantages of the co-design, which is expected to obtain a fully integrated system with good overall performance for realtime wireless control.