Routing Algorithms for Preventing Energy Holes and Improving Fault Tolerance in Wireless Sensor Networks

We investigated energy efficiency and fault tolerance for wireless sensor networks (WSNs), addressing the need to minimize the communication distances so that the energy used for communication is minimized since energy consumption is proportional to the 2nd to the 6th power of the distance. We also investigated the energy hole phenomenon, in which non-uniform energy usage among nodes causes some of the nodes to run out of power sooner. This in turn increases the communication distances and results in premature shutdown of the entire network. Since some sensor nodes in a WSN may be unreliable, fault tolerance is required for optimizing the communication topology. We have developed a routing algorithm, the "energy hole aware energy efficient communication routing algorithm (EHAEC)," that solves the energy hole problem to the maximum extent possible while minimizing the amount of energy used for communication by generating an energy efficient spanning tree. A variation of this algorithm, EHAEC for one-fault tolerance (EHAEC-1FT) identifies redundant communication routes by using the EHAEC tree and tolerates the failure of one node. In evaluation simulations, EHAEC outperformed direct data transmission by more than 3.4 to 4.8 times in terms of energy efficiency, thereby extending the WSN lifetime. EHAEC-1FT outperformed EHAEC in terms of energy efficiency when fault tolerance was the first priority and fault tolerance redundancy was created when or before a failure occurred.