Energy-efficient body channel communication for body area networks

Abstract

A data communication system, utilizing energy-efficient body channel communication (BCC) technology for body area networks, is presented. And this dissertation introduces reliability problem in BCC technology and suggests spread-spectrum technique as a solution. To establish data communication system for multimedia data transmission between mobile devices, a wideband signaling (WBS) and a direct-coupled interface (DCI) technique are adopted with single metal electrode. The channel investigation of BCC using the DCI identifies the relation between signal transmission characteristic and return path strength, and provides more realistic channel model. With this investigated channel model, an optimum channel bandwidth of 50 MHz to 150 MHz is established and called as a body-wire frequency (BWF) band. A communication link is analyzed to determine design parameters for the energy-efficient signal transmission. A proposed WBS transceiver transmits data with direct digital transmit. An analog front-end, which includes the preamplifier, the Schmitt trigger and level shifter, receives the signal from human body and recovers data. For point to point data communication, a simplified MAC layer describes communication protocols and frame structure. To achieve maximum frame success ratio, fame size and re-transmission timeout is determined as 70 byte and 100ms, respectively. The transmission of image data through the human body is successfully demonstrated by using the prototype transceiver module and the mobile phone. Despite of its high energy efficiency of sub nJ/b, the BCC has a reliability problem due to an interfering signal caused by the ‘body antenna effect’. We measure the intrabody interference from 30MHz to 130MHz frequency range, and develop its statistical model. The spread spectrum (SS) technique can be applied to the BCC system to avoid the interference. And the bit error probability (BEP) is evaluated by using the interference model. The analysis shows tha...