Impact of Sink Node Placement on Partial Connectivity in Wireless Sensor Networks

Network connectivity as a fundamental issue in WSNs has been attracting researchers' attention for decades, primarily focusing on strategies to achieve or maintain full connectivity. However, in practice, sensor isolation is a state of normality, and full connectivity is not a requirement for many WSN applications to operate successfully. Due to this, this paper investigates the partial connectivity problem in a randomly deployed WSN, taking into consideration the particular function of the sink node and its skewed placement due to environmental and terrain factors in network deployment. We strive to identify the tradeoffs between partial connectivity and the required network parameters in contrast to full connectivity under various circumstances. Through mathematically modeling, theoretical analysis and simulation evaluations, we demonstrate the significant impact of the sink node and its placement on the network connectivity and that partial connectivity, as compared with full connectivity, is a more appropriate metric to assess the connectivity of random WSNs. For example, we show that the sensor connection rate drops from 98.8% to 72.5% when the sink node is relocated from the network center to the border and that 1.367 times more energy is needed to connect less than 4% of the remote sensors, under the studied network settings. The results help in defining appropriate performance metrics and in selecting critical network parameters for real-life WSN design and implementation.