Novel Network Structure and its Clustering Scheme Based on Residual Power for Wireless Powered Wireless Sensor Networks

In wireless sensor networks (WSNs), wireless power transfer (WPT) has been studied as an energy-harvesting technique for prolonging their network lifetime. The WPT can supply power resources to sensor nodes (SNs) wirelessly, however, the reception (harvesting) power at SNs depends on their distance from a WPT equipment (WPTE), leading to the location-dependent non-uniformity in the reception power among SNs. For the fixed-located WPTE, SNs distant from the WPTE suffer from insufficient reception power. To handle this problem, this paper proposes a novel network structure introducing multiple hybrid access points (HAPs), which equip two functions of conventional cluster head function, including data collection and relay transmission, and WPT function. Then, these HAPs take terms providing both functions. By periodically rotating the HAP providing the WPT function, the location of the WPTE can be changed, which reduces the non-uniformity in the SN reception power. Also, this paper proposes a clustering scheme based on the residual power at SNs to reduce their power depletion under the proposed network structure. The evaluation results through computer simulation show that the proposed system reduces the non-uniformity in the SN reception power and the power depletion at the SNs and then improves the data collection rate, compared with the conventional systems.