Empirical analysis of the hidden terminal problem in Wireless Underground Sensor Networks

Wireless Underground Sensor Networks (WUSNs) can be widely adopted to monitor the environment in agricultural, security and ecological applications. In most applications, besides underground sensor motes, aboveground motes are deployed to gather information. However, due to the different communication ranges of the channels, hidden terminal problem occurs when multiple underground motes send data to the aboveground mote. In this paper, experiments are conducted to reveal this problem in WUSNs empirically. In addition, an RTS/CTS scheme is implemented to eliminate this problem and it is shown that the communication success can be increased from 32% to 76%. More importantly, despite its improvements in collisions, RTS/CTS schemes alone cannot guarantee successful multi-access operation due to the high variance in channel quality in WUSNs, which motivates further research in this area.