Interference Cancellation at the Source for Passive Wireless Sensing Applications

Wireless sensor networks operating on a battery source have limited lifetime and can not be used in extreme environments. Passive sensors (battery-free) on the other hand may operate for a long time even in harsh environmental conditions. Passive sensors are powered using radio frequency waves and reflect a modified signal transporting the measured parameter that is embedded in the reflected wave. There are three dimensions where we can embed information and operate in an orthogonal fashion to support multi sensor operations: time domain, frequency domain, and code domain. One of the major challenges in such networks is the interference management to support scalability as the number of sensors grow to support a variety of applications. There has been several methods in time, frequency, and code domain to minimize the interference after it happens. In this paper, a novel interference mitigation method is proposed, which limits interfering signals at each source preventing their aggregation beyond repair at the receiver.