  Wireless sensors in extreme environments such as underground, concrete wall,
and the human body, can enable a large number of important applications.
However, deploying wireless sensors in such environments on a large scale is a
great challenge due to the high cost and the large profile of wireless sensors.
Backscatter communications can reduce the cost and size of wireless sensors by
removing most of the typical wireless components. In this paper, we propose to
leverage the RFID sensors for inter-media magnetic induction-based backscatter
communications (MIBC). In this way, the complexity and cost of wireless sensors
can be significantly reduced. The sensors leverage magnetic signals to
backscatter information which demonstrate high penetration efficiency. We
design a system with channel estimation and optimal signal transmission
strategy, and an optimal receiver. The channel between the aboveground reader
and underground sensors are modeled by using a stratified medium model. The
bit-error-rate is evaluated with different configurations. The results suggest
that MIBC can be utilized for most of the inter-media applications with low
power consumption and high penetration efficiency.
