Ubiquitous WSN for Healthcare: Recent Advances and Future Prospects Yuan Zhang, Senior Member, IEEE, Limin Sun, Member, IEEE, Houbing Song, Senior Member, IEEE, and Xiaojun Cao, Member, IEEE Abstract—Wireless sensor networks (WSNs) have witnessed rapid advancement in medical applications from real-time telemo- nitoring and computer-assisted rehabilitation to emergency response systems. In this paper, we present the state-of-the-art research from the ubiquity perspective, and discuss the insights as well as vision of future directions in WSN-based healthcare systems. First, we propose a novel tiered architecture that can be generally applied to WSN-based healthcare systems. Then, we analyze the IEEE 802 series standards in the access layer on their capabilities in setting up WSNs for healthcare. We also explore some of the up-to- date work in the application layer, mostly on the smartphone platforms. Furthermore, in order to develop and integrate effective ubiquitous sensing for healthcare (USH), we highlight four impor- tant design goals (i.e., proactiveness, transparency, awareness, and trustworthiness) that should be taken into account in future systems. Index Terms—Healthcare applications, smartphone, system design goals, tiered architecture, ubiquitous sensing, wireless sensor network (WSN). I. INTRODUCTION A DVANCES in microelectromechanical systems and wire- less sensor networks (WSNs) have opened up great opportunities for modern healthcare. The future will see more and more integration between current specialized medical re- sources and wireless sensor technologies to match the expectation that healthcare should not be fragmented and epi- sodic. Given the broad range of possible medical applications and needs, it is impracticable to apply the same sensor and wearable monitoring platform everywhere [1]. Therefore, it is important to realize the pros and cons of various solutions, and accordingly select the most promising technology for a given scenario. Traditionally, healthcare systems highly concentrate on hos- pitals and clinics. The new venue of care moves to the patient’s home, where clinician can combine modern information tech- nologies with old-fashioned human caring [2]. Particularly, WSNs have become indispensable in the realization of smart homes [3]. The embedded wireless sensors interact with the inhabitants to form an intelligent environmental network. Some users even desire the capability to provide continuous medical monitoring and emergency communication outside the home. In practice, a main concern is to select appropriate technical standards and protocols from three categories: 1) medical sys- tems; 2) wireless communications; and 3) wireless specific devices. In this paper, we will focus on the second category, while briefly mentioning the first and last categories. For wireless communications, there are many well established and fast grow- ing standards within the IEEE communications society such as IEEE 802.11, 802.15, 802.16, 802.20, and 802.22 series. However, several key issues are still open and deserve further investigation from the community. For instance, which IEEE communication standards are appropriate enablers for certain health service? What are the suitable candidate technologies for the clinical applications at hand? What are the ultimate goals of future ubiquitous healthcare and how do we prepare for it? In this paper, we propose an interesting tiered architecture for WSN-based healthcare systems. We then summarize the distinct sensor network technologies for healthcare services and extend the vision to explore the design goals of future WSN-based healthcare systems. In addition to technology developments, other aspects related to human willingness, medical practice, regulations, and practical implementation issues are key corre- lation forces. These factors are combined to extract the four important design goals of ubiquitous sensing for healthcare (USH), which include proactiveness, transparency, awareness, and trustworthiness. II. SYSTEM ARCHITECTURE Designing a system architecture is usually the first step toward a solution. Several papers have explicitly illustrated their system models designed to meet the practical needs [5]–[7]. For 2327-4662 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. Manuscript received March 18, 2014; revised May 01, 2014; accepted June 03, 2014. Date of publication June 6, 2014; date of current version August 01, 2014. This work was supported in part by the National High-tech R&D Program of China under Grant 2013AA014002, in part by the National Natural Science Foundation of China under Grant 61202066, in part by the Natural Science Foundation of Shandong, China under Grant ZR2013FM004, in part by the China Postdoctoral Science Foundation under Grant 2013M530074, and in part by the Open Research Fund of Shandong Provincial Key Laboratory of Computer Network. The work of H. Song was supported by the West Virginia Higher Education Policy Commission under Grant FRT2W762W. Y. Zhang is with the Shandong Provincial Key Laboratory of Network Based Intelligent Computing, University of Jinan, Jinan 250022, China, with the Beijing Key Laboratory of IOT Information Security Technology, Institute of Information Engineering, Chinese Academy of Sciences (CAS), Beijing 100093, China, and also with the Shandong Provincial Key Laboratory of Computer Network, Shandong Computer Science Center, Jinan 250014, China (e-mail: yzhang@ujn.edu.cn). L. Sun is with the Beijing Key Laboratory of IOT Information Security Technology, Institute of Information Engineering, Chinese Academy of Sciences (CAS), Beijing 100093, China (e-mail: sunlimin@iie.ac.cn). H. Song is with the Department of Electrical and Computer Engineering, West Virginia University, Montgomery, WV 25136 USA, and also with the West Virginia Center of Excellence for Cyber-Physical Systems, Montgomery, WV 25136 USA (e-mail: Houbing.Song@mail.wvu.edu). X. Cao is with the Department of Computer Science, Georgia State University, Atlanta, GA 30302 USA (e-mail: cao@gsu.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JIOT.2014.2329462 IEEE INTERNET OF THINGS JOURNAL, VOL. 1, NO. 4, AUGUST 2014 311