## 6 Conclusions  
This study presents an analysis of our long-term outdoor WSN, with both commercially available and open source networking software for TinyOS-based WSN platforms. This work represents a novel effort for the empirical evaluation of multi-hop real-world environmental monitoring WSNs, focusing on network performance and network costs. We observed that around 3%-4% of all the packets received at the gateway were duplicates when using XMesh, which indicate a significant number of unnecessary transmissions within the network. This issue is mostly resolved with the use of CTP, where the duplicate packet control is carried at the first transmission hop for each node, avoiding unnecessary transmissions towards the sink node. The network analysis shows that only 0.2% of the packets received using CTP corresponded to duplicates. Based on the network statistics collected from the ASWP WSN testbed, a highly used path across the network was found in forwarding activities. For XMesh, nodes located closer to the base station created a bottle neck, responsible for most of the packet retransmissions and drops, reducing the network performance. In CTP, nodes along this highly used path are able to handle the network traffic load; however, these nodes consume more energy than their neighbors and network partitions may occur once their batteries are depleted. Unexpectedly, it was found that nodes with relatively low path costs were associated with poor PSR under XMesh (especially for nodes close to the base station), which resulted in significant retransmissions and packet loss. In contrast, appropriate high transmission costs are assigned to these nodes in CTP, avoiding the unnecessary expenditure of power (due to retransmissions) and improving the success rate of packet reception at the base station. PRRs at the node level also present important differences between the two analyzed deployment approaches. In XMesh, it was found that nodes deployed closer to the base station are able to maintain PRRs of 50% and above, only up to 61%, while nodes located farther from the base station obtain PRRs fluctuating between 15% and 40%. This behavior changed in CTP, where nodes located both close to and far from the base station could achieve PRRs higher than 90%. However, some specific node locations exhibit lower performance (_i.e._, nodes 1070, 1080, 3025, 3085, 5043) throughout the deployment field. The PSR was included as an additional indicator of the network performance. When using XMesh, the entire network maintains a PSR between 45% and 53%, while PSR values range from 15% to 79% for individual nodes closer and in direct connection with the base station. These results are lower than those obtained with CTP, which achieved 96% PSR for a six-month period, evidencing critical differences between these two WSN routing protocols and their reaction to ASWP's outdoor conditions. In summary, the analysis revealed numerous issues pertaining to the XMesh performance (and ultimately the increased maintenance) of the network, including the presence and transmission of duplicate packets, the presence of congestion along highly used paths, the utilization of under-performing nodes for packet forwarding, and network partitioning. For the CTP-based application, packet duplicates, poor forwarder selection, and congestion were no longer an issue; however, network partitioning remains. Network partitions may significantly reduce the network performance as nodes within the highly used path deplete their batteries resulting in entire sections of the WSN unable to reestablish a path towards the sink node. At the ASWP testbed, network partitions are mainly consequences of both maintenance related events (e.g., hardware failures, battery depletions) and the behavior of the routing protocol (the capacity of the protocol to recover the routes when possible.