RF power source and estimation diversity in distributed sensing with passive wireless communications

Sensor nodes constitute a distributed wireless sensing architecture, such that, multiple sensors report their observations. However, sensor networks are comprised of energy-constrained nodes. Therefore, there have been many efforts to devise energy-efficient communication algorithms for sensor networks to achieve reliable and energy-efficient distributed wireless sensing. Recently, to mitigate battery depletion problem and extend network lifetime, wireless passive sensor networks (WPSN) have become a new field of interest. Modulated backscattering is an important communication technique in WPSN to alleviate reaching unlimited lifetime for sensor nodes. In this paper, we theoretically analyze event distortion in WPSN that is employing modulated backscattering for communication. First, we model backscattered power by sensor nodes at RF sources using log-normal channel model. Then, using the backscattered power gain of sensor nodes, the mean square error of estimated signal is analyzed for various number of RF sources and power levels in WPSN. The objective of this work is to reveal the impact of RF source diversity on event estimation distortion in WPSN.