## 8 Discussion  
Wireless medical sensor networks make patients' life more comfortable and provide viable solutions for healthcare applications such as vital sign monitoring, hospitals, home care, ambulatory care, clinical monitoring. The success of wireless healthcare absolutely depends on security as well. Security in healthcare application using wireless medical sensor networks is an emerging research topic and it is worth studying. This paper provides a fairly comprehensive study of security research in healthcare application using WMSNs. In wireless healthcare, patient health data floats on wireless communication, so malevolent users must not be underestimated. Since wireless communication ranges are not confined, malevolent threats even pose more significant risks to the patient. For example a patient's body data can be accessed in an unauthorized manner, can be modified, and consequently this can pose a life-threatening risk. Currently, appears that researchers have limited awareness of the patient risks. Most of the popular research projects acknowledge the issue of security, but they fail to implement strong security services that could preserve patient privacy (_cf._ Section 2), e.g., CodeBlue [7], Alarm-Net [13], UbiMon [14], MobiCare [16,53], STAIRE [55]. As result, a healthcare provider using [7,13,14,16,53,55] a system that permitted malevolent or others user to access the health data could be held liable for violating the Health Insurance Portability and Accountability Act (HIPAA) [39]. However, upcoming work is required in particular to consider the security and privacy issues for such applications where people life's at high risk. To maintain strong security in a real-time healthcare application, security and privacy needs to be included from the starting point of application design, deployment, and implementation. HIPAA regulated stringent rules for healthcare providers (_cf._ Section 4), _i.e._, individuals' vital signs are exposed to authorized professionals (_i.e._, doctors, caregivers and nurses) [39,78]. A strong user authentication (_i.e._, professional authentication) protocol at the application layer has not yet been addressed effectively in order to prevent illegal access to wireless medical sensor data, so user authentication is highly desirable in such wireless healthcare applications. The aim of wireless healthcare is to let patient to survive when he/she is alone or wants to live an independent life, so mobility of the patient must be maintained, therefore there is need of such a security mechanism that can quickly adapt to dynamic topologies. However, little research deals with dynamic topologies, such as Alarm-Net, where the project is platform dependent. It could not support a secure handover mechanism to another network device, if a patient moves from a home network to a foreign network. So, future researchers or projects might pay attention to securing patient mobility while he/she is moving from network to network. Researchers also have to carefully consider communication overhead, because any security protocols add computation and communication overhead. Since a high throughput is essential for health data, security protocols should be cost effective in terms of computation and communication costs. Wireless healthcare applications need time for a synchronization protocol to compute end-to-end delay of packets for real-time analysis. Thus, the healthcare monitoring applications should be time synchronized that compute the end-to-end time delay between the medical sensors and the base-stations. More specifically, the time synchronization is more important for patient location tracking because patients' body sensors need to do collaborative work such as sensing tasks, patient tracking, data routing and data aggregation. However, in healthcare application none of the aforementioned time synchronization schemes were designed with security in mind.