A Survey on Holes Problem in Wireless Underground Sensor Networks

The paper aims to put in the forefront a survey on the problem of the existing holes in the Wireless Underground Sensor Networks (WUSNs). Anomalies in wireless sensor networks can weaken the network by impeding its functionalities. These existing anomalies commonly known as holes may cause irreversible devastating problems and may prove fatal to humans. There can be different holes in the network, such as coverage hole, routing hole, jamming hole, sink/ worm hole, etc. This paper intends to discuss various holes problems in WUSNs, reasons behind their occurrence, and different techniques to mitigate the issues. An efficient hole detection technique shall increase network lifetime, use lesser resources and give accurate results with zero false positives. To put a light on the present scenario, methods/ techniques used to cope with different types of holes have been discussed in detail presenting their analysis, constraints, and advantages. Besides, it would also touch upon the comparative analysis in terms of soundness and limitations of these techniques. The study is concluded with future research directions.