Key Communication Techniques for Underground Sensor Networks

Wireless Underground Sensor Networks (WUSNs) are the networks of wireless sensors that operate in the underground soil medium. In this monograph, to realize reliable and efficient WUSNs, two enabling techniques are developed to address the challenges brought by the underground soil medium, including the EM wave-based WUSNs and the MI-based WUSNs. For EM wave-based WUSNs, the heterogeneous network architecture and dynamic connectivity are investigated based on a comprehensive channel model in soil medium. Then a spatio-temporal correlation-based data collection scheme is developed to reduce the sensor density while keeping high monitoring accuracy. For MI-based WUSNs, the MI channel is first analytically characterized. Then based on the MI channel model, the MI waveguide technique is developed in order to enlarge the underground transmission range. After that, the optimal deployment algorithms for MI waveguides in WUSNs are analyzed to construct the WUSNs with high reliability and low costs. Finally, the mathematical models are developed to evaluate the channel and network capacities of MI-based WUSNs. This monograph provides principles and guidelines for WUSN designs.