  The use of wireless implant technology requires correct delivery of the vital
physiological signs of the patient along with the energy management in
power-constrained devices. Toward these goals, we present an augmentation
protocol for the physical layer of the Medical Implant Communications Service
(MICS) with focus on the energy efficiency of deployed devices over the MICS
frequency band. The present protocol uses the rateless code with the Frequency
Shift Keying (FSK) modulation scheme to overcome the reliability and power cost
concerns in tiny implantable sensors due to the considerable attenuation of
propagated signals across the human body. In addition, the protocol allows a
fast start-up time for the transceiver circuitry. The main advantage of using
rateless codes is to provide an inherent adaptive duty-cycling for power
management, due to the flexibility of the rateless code rate. Analytical
results demonstrate that an 80% energy saving is achievable with the proposed
protocol when compared to the IEEE 802.15.4 physical layer standard with the
same structure used for wireless sensor networks. Numerical results show that
the optimized rateless coded FSK is more energy efficient than that of the
uncoded FSK scheme for deep tissue (e.g., digestive endoscopy) applications,
where the optimization is performed over modulation and coding parameters.
