Energy-Efficient Relay Selection with Blockage for LOS Transmissions in Wireless Sensor Networks

In this paper, an energy-efficient relay selection (RS) algorithm is proposed for line-of-sight (LOS) transmissions in wireless sensor networks (WSNs) with blockage. To find the energy-efficient routing for given sensor and sink node pair, the best RS criteria are employed to approach the optimal relay position (ORP) of the effective relay search region (RSR) in multiple different ways. For example, the minimal distance criterion is used to generate the minimal RSR centered on ORP during the initial selection phase. Subsequently, we enlarge RSR and apply the minimal impact-probability criterion to reduce the impact of obstacles on energy efficiency for LOS transmissions. Lastly, the minimal projection criterion is used to refine the results of RS based on the minimal impact-probability criterion. Simulation results show that the proposed algorithm based on the best RS criteria with composite ways is able to reduce the energy consumption as well as the impact of obstacles when the RSR's radius increment is less than a certain threshold.