Energy-efficient off-body communication nodes with receive diversity

Abstract

Abstract-Off-body wireless communication applications range from fall-detection systems for the elderly to monitoring networks for rescue workers. Further development of practical body-worn systems requires compact, low-cost and low-power battery-powered equipment. A versatile wearable network node offering all these features, including a powerful microcontroller for data processing and additional memory for local data logging was designed and implemented. The node allows receive diversity, mitigating the negative impact of fading, which is typically present in indoor propagation environments. Channel measurements are performed for an indoor Non Line-of-Sight communication between two nodes. Mobile-to-base-station as well as mobile-to-mobile links are considered. A statistical analysis of the performance determines outage probability with and without receiver diversity for both link types, showing a significant diversity gain in all cases. Correlation properties, level crossing rate and average fade duration are also determined.

Correlated shadowing and fading characterization of MIMO off-body channels by means of multiple autonomous on-body nodes

“…The test person performs a random walk in the indoor environment where the propagation between the TX and RX areas is NLoS (Non Line-of-Sight), as confirmed by previous measurement campaigns [19]. The trajectory of the walking test person is confined within the TX area indicated in Fig.3, to provide a nearly constant path loss.…”

“…Diversity reception is possible using a single node, but only one packet can be received at a given time, hence in such a setup each packet would have to be transmitted twice, as in [19]. The latter approach would lower the correlation between the receive antennas in the 4×2 MIMO link due to time diversity and therefore was not preferred here.…”

Role of Body Area Sensor Networks in Smart Health Care

“…To reduce this we present an effective method using wireless sensor networking in body area networks [5], [6] the "Amplifier Ear". This amplifier ear circuit, connected to 32 Ohm impedance mini-earphones, can detect very remote sounds.…”