Maximising energy efficiency for direct communication links in wireless body area networks

Abstract

Energy efficiency is a fundamental aspect for wireless body area networks (WBANs) due to the limited battery capacity and miniaturisation of sensor nodes. Prolonging the lifespan of a WBAN depends mostly on maximising the energy efficiency. WBAN systems operate under conflicting requirements of energy and spectrum efficiency. In this study, the two metrics of energy and spectrum efficiency for direct communication links for in-body and on-body sensor nodes are analysed. A general device-to-device communication model was adapted to WBAN. Optimal transmission power values to achieve maximum energy efficiency for in-body and on-body communication links are found. With reference to a maximum power level of 1.5 W compliant with the Federal Communications Commission for WBAN, it is also deduced that for on-body communication, decreasing maximum possible spectrum efficiency by 33% for medical devices operating in 400-450 and 950-956 MHz would improve energy efficiency by 75 times. Moreover, by decreasing spectrum efficiency by 38.3 and 48% leads to an increase in energy efficiency by 45.3 and 39.3 times in 2.4-2.5 and 3.1-10.6 GHz frequency bands, respectively. This tradeoff is significant for medical applications having strict energy requirements.