Development of an Encrypted Wireless System for Body Sensor Network Applications

Wireless body area networks (WBAN), also called wireless body sensor networks (WBSN), consist of a collection of wireless sensor nodes used to monitor and assess various human physiological conditions, which can then be used by healthcare professionals to help them make important healthcare decisions. They can be used to prevent disease, help diagnosis a disease, or manage the symptoms of a disease. An extremely important aspect of WBAN is security to protect a patient's healthcare information, as a hacker could potentially cause fatal harm. Current security measures are implemented in software at the MAC layer and higher, not in the physical layer. Previous research demonstrated a chaotic encryption cipher to add a layer of security in the physical layer. This cipher exploits different properties of the Lorenz chaotic system to encrypt and decrypt digital data. Decryption involved synchronizing two chaotic signals to recover original data by sharing a state between the transmitter and receiver. In this thesis, we further develop the encryption system by implementing wireless capabilities. We use two approaches: the first by using commercially available wireless microcontrollers that communicate using Bluetooth Low Energy, and the second by the design and fabrication of a dual-band low noise amplifier (LNA) that can be used in a receiver for WBANs collecting data from implantable and on-the-body sensors. For the first approach, a custom Bluetooth Low Energy profile was created for streaming the analog encrypted signal, and signal processing was done at the receiver side. For the second approach, the LNA operates at the Medical Implant Communication System (MICS) band and the 915 MHz Industrial, Scientific, and Medical (ISM) band simultaneously through dual-band input and output matching networks.