Energy-efficient body-coupled data transceiver for body area networks

Abstract

This dissertation presents two energy-efficient data transceivers utilizing a human body itself as a data transmission medium, called body-coupled communication (BCC) technology, for body area network applications. Firstly, for point-to-point data communications applicable to multimedia data transmission, the proposed BCC scheme is based on wideband signaling (WBS) and adopts a direct-coupled interface (DCI) with only a single electrode of $50-\omega$ impedance. The channel investigation with the DCI identifies an optimum channel bandwidth of 10-kHz to 100-MHz. A WBS communication link is modeled to specify link parameters for the energy-efficient data transmission. A low power WBS transceiver includes a direct digital transmitter, a receiver analog front-end (AFE) and an all-digital clock and data recovery (CDR) circuit. To further reduce power consumption, the AFE employs a low power wideband op amp and the CDR circuit incorporates a low-voltage digitally-controlled oscillator and a quadratic sampling technique. The WBS transceiver chip with a $0.25- \mu m$ standard CMOS technology has 2-Mb/s data rate at a bit error rate of $10^{-7}$, dissipating only 5-mW from a 1-V supply. Its bit energy achieves 2.5-nJ/b, 26 times more efficient than other BCC transceivers. The transmission of MP3 audio data through the human body is successfully demonstrated by using the prototype WBS transceiver chip with the proposed BCC scheme. Secondly, an energy-efficient PHY transceiver is presented for point-to-multipoint data communications in body sensor networks applicable to healthcare monitoring. An energy model of the PHY transceiver is proposed and its architecture is optimized by a scalable spreading factor with respect to bit energy efficiency. The scalable spreading and modulation technique exploits 3-level pulse position modulation and direct sequence spreading spectrum to deliver various physiological signals in wide data rate range. The dedicated packet format is de...