Cooperative magnetic induction based through-the-earth communication
Magnetic Induction (MI) is a through-the-earth (TTE) communication technique which can accomplish reliable wireless propagation with long distance. When used in underground mines, MI-based transmit distance is limited by several factors: high path loss, limited size for transmitter antenna due to the narrow underground space, and limited transmitting power due to anti-explosion regulations. In this paper, a method called cooperative magnetic induction (CMI) is presented to increase the TTE propagation range. Specifically, we propose two types of CMI according to different installation of the antenna coil: fixed-angle cooperative magnetic induction and optimal-angle cooperative magnetic (OCMI). Compared to MI, the latter can bring >20% increase in the transmitting distance.