Communication and Security Trade-Offs for Battery-Powered Devices: A Case Study on Wearable Medical Sensor Systems

In order to reduce the workload of hospital staff and to provide better services to hospitalized patients, attempts are made to integrate patient monitoring systems directly into hospital networks. Monitoring systems must respond to more and more technological challenges. They are ideally portable and wireless, to free the patient from the hospital bed. At the same time, to enable better patient follow-up, a large amount of information needs to be transmitted and processed in real time. Challenges in the design of such systems include energy-efficient processing and communication, and guaranteeing the security of the measured data. This paper describes a wearable sensor system, integrated into a hospital network, that supports high data rates generated by multiple sensors. With a strongly motivated focus on end-to-end security, we explore trade-offs with respect to security schemes and implementations, and wireless network protocols. The results show that the energy efficiency of the resulting system is comparable to existing systems that support far less sensor data and that compromise on end-to-end security by offloading security operations to a delegation server. To our knowledge, this is the first work that explores the impact of the security scheme and the wireless network protocol on the energy consumption of a wearable device, while providing true end-to-end security.