## 1 Introduction  
Smart healthcare [1] has attracted more and more worldwide attention due to its advantage of flexibility, mobility, and ease of constant monitoring of the patient. Smart healthcare, an integration of various information technologies including Internet of Things (IoTs) [2], cloud computing, and big data processing, aims at building a remote disease prevention and care platform. As a great driving force of the Fourth Industrial Revolution, the IoT is playing an ever more important role in Intelligent Manufacturing, the Smart Grid, Smart Cities, Vehicular Ad Hoc Networks (VANETs), Smart Healthcare, etc. The notion of the IoT can be regarded as an extension of communication networks and the Internet;it employs sensing technology and intelligent devices to perceive and recognise the physical world, conducts calculations, processes and mines knowledge through network transmission interconnections. Further, IoT realises information exchanges and seamless connections between things and things and persons and things to effect real-time control, precise management, and scientific decision-making. In future networks, the IoT will be able to integrate sensors, wireless communication, embedded computing, cloud computing, big data, etc., and to apply intelligent terminals, mobile computing and the ubiquitous network to all aspects in people's daily lives. Therefore, IoT is a key to solve growing global demand for satisfactory medical services. As the core technology of medical IoT, wireless body area network (WBAN) can be used for real-time patients monitoring and home healthcare, has wide application prospects, and has huge market potential. WBAN can automatically collect human Electrocardiograph (ECG), Electroencephalograph (EEG), Electromyogram (EMG), body temperature, blood pressure, blood sugar, blood oxygen, and other life sign parameters from the pre-deployed sensors on the patient's body surface or inside their body. This in in order to achieve real-time, convenient, all-weather healthcare monitoring, thus providing a flexible and effective means for real-time healthcare monitoring of patients inside and outside the hospital room, and in Intensive Care Units (ICUs). In the recent years, the emergence of wireless sensor networks in healthcare systems has significantly increased, mainly in the areas of remote health monitoring, medical data access, and communication with caregivers in emergency situations. Using WSN, we can easily design a simple but efficient system to monitor the conditions of patient continuously. Patients can be tracked and monitored in normal or in emergency conditions at their homes, hospital rooms, and in ICUs. In most countries, soaring medical expenses and the declining availability of medical services have become the main challenges to be addressed by medical and health services at present. Because of the large global population, overall medical resources are relatively scarce. Furthermore, high-speed economic development will also bring about problems such as population aging, rapid growth of chronic diseases, and high sub-health ratio. Therefore, smart healthcare becomes an effective way to fundamentally solve the problem of inadequate and overly expensive medical services by using information technology to change the existing medical service mode and improve the utilization of medical resources. Figure 1 depicts the convergence architecture of smart healthcare. Due to the inherent nature of a wireless medium, sensors and link failures often occur because of energy depletion, channel fading, faulty configuration, malicious attacks, etc., in the harsh emergency ward environment. A traditional fault-tolerant scheme with a resource-hungry backup path would require a large amount of redundancy. Additionally, traditional reactive fault-tolerant mechanisms provide protection only after errors occur, resulting in longer delays. Moreover, taking into account the complexity of the smart healthcare environment, previous schemes cannot be applied directly to healthcare monitoring systems.