# Joint Balanced Routing and Energy Harvesting Strategy for Maximizing Network Lifetime in WSNs
## 5 Simulation Results  
To validate the effectiveness of the proposed strategy, the network performances of energy routing protocols including the proposed SPT-LBR and the conventional Dijkstra algorithms are both investigated. To estimate the energy routing performances, a two-dimensional planar network with one data sink (Identification, ID 41) and 80 CHs nodes are studied here. The 80 CHs are even distributed in a given operation area and each cluster owns several sensors to detect the cluster area. Figure 6: The illustrated flowchart of power harvest scheme. The four primary nodes in the SCA are 32, 41, 42, and 50. The SPT-EBR and the Dijkstra algorithms are both applied to compute the shortest paths with various forward awareness factors including the packet forwarding rate and the energy harvesting rate. With regard to the packet transmission, each sensor sends packets to the CHs and each CH fuses data as well as forwards them to the sink periodically. Two performances including the power consumption rate distribution and the network lifetime are compared between the power consumption scheme, power harvesting scheme, and the Dijkstra algorithm. Figure 7 shows the power consumption rate distribution of the power consumption scheme in the red line and the Dijkstra algorithm in the blue line are both examined. In the Dijkstra algorithm, node 32 has the greediest power consumption compared to the other primary nodes, and is nine times than node 50 in average power consumption. In the power consumption scheme of SPT-EBR, the highest power consumption is at nodes 50, 1.4 times than node 41 in average power consumption. As a result, the power consumption scheme achieves better energy utilization with the load balance factor design. From the perspective on hotspot nodes distribution, the hotspot nodes 14, 23, 32, 40, and 42 are spatially distributed in the inter-layers by the Dijkstra routing. With the assistance of the power consumption scheme, the hotspot nodes can be evenly distributed around the sink connectivity area. In addition, the power consumption rate distribution in each intra-layer is more even than the conventional scheme. Figure 7: The power consumption rate distribution of the power consumption scheme in Shortest Path Tree with Energy Balance Routing strategy (SPT-EBR). In Figure 8, the power consumption rate distribution of the larger network with 169 nodes for both the power consumption scheme and the Dijkstra algorithm are investigated. In the Dijkstra algorithm, node 72 encounters the highest power consumption rate than all the other primary nodes and there is 13 times than node 98 in average power consumption. This may lead to an inevitable energy unbalance problem in hotspot nodes as the network size grows. In the power consumption scheme of SPT-EBR, the highest power consumption rate is occurred at nodes 98 and there is 1.56 times than node 86 in average power consumption. With the load balance factor to select the next forwarding node, the power consumption scheme achieves better energy utilization than the Dijkstra algorithm. In addition, the energy unbalance problem can be controlled with the packet forwarding rate factor in the power consumption scheme. To evaluate the energy harvesting scheme, a uniform distribution of energy harvesting mode is introduced here to perform the simulation. The energy harvesting strategy includes the full nodes charging and the partial nodes charging strategies. The partial nodes charging strategy is designed to charge the 20% heavy traffic nodes and save the deployment cost in realizing the energy charging. The power charging value is uniformly distributed from 0 to 18 for the energy harvesting scheme and the average battery charging rate of the overall nodes is 7. Figure 9 shows the power consumption rate distribution of the energy harvesting scheme and both schemes achieve the identical power consumption for the four primary hotspot nodes. In general, the full nodes charging method achieves  
Figure 8: The power consumption scheme for larger SPT-EBR networks.