## 5 Performance Analysis
### Simulation Results and Discussions  
Two experiment scenarios, experiment scenarios (a) and experiment scenarios (b), were done for performance analysis of safety period, energy consumption, packet delivery ratio, and end-to-end delay. In the scenarios (a), the performance was observed under fixed source packet rate of 1 packet/second against varied source-sink distance. The source-sink distance was varied between 10 and 70 hops. In scenarios (b), performance was observed under fixed source-sink distance against varied source packet generation rate. The source packet generation rate was varied from 1 to 7 packet/second. For the analysis of attack success rate, three experiment scenarios were done. In scenario (a), the attack success rate was observed against varied number of sensor nodes in the network. In scenario (b), the attack success rate was observed at varied network size. In scenario (c), the attack success rate was observed against varied adversary detection range. Figure 5 shows the privacy performance of the protocols. The figure shows that the TreeR protocol achieves very strong SLP protection. The TreeR achieves longer safety period by integrating many routing techniques. It employs phantom nodes located far away from the source node. It also employs significantly long backbone routes with many diversionary routes. At the end of each diversionary route, fake packets are emitted periodically. As a result, the eavesdropping adversary is effectively obfuscated and long safety period is guaranteed. However, the use of long backbone routes, diversionary routing paths which diverge to the network border regions, and the distribution of fake packet traffic at the end of each diversionary route introduce very high communication overhead as shown in the next paragraphs. The figure also shows that the proposed PhaT protocol achieves relatively short safety period compared to the TreeR protocol. However, compared to the traditional Pha protocol, the PhaT protocol offers significantly longer safety period. For example, at 60 hops from the sink node, the safety period of the PhaT is approximately 4 times higher than Pha protocol. Since PhaT can achieve approximately 4 times higher safety period than the Pha protocol, we consider the level of SLP protection for PhaT to be effectively strong. Also shown in the Figure 5a, the proposed PhaP protocol achieves significantly longer safety period than the existing ProbR protocol. The ProbR protocol achieves a relatively short safety period because the fake packet source is located away from the real source node, on the opposite side of the real source node. Also, the real packet routes and fake packet routes are not exactly homogeneous due to the location of the fake packet sources being in the near-sink region. The fake packet routes are relatively short. As a result, it has a small effect on the privacy protection. After sometime of traffic analysis attack, adversary can predict the real packet routes and perform a more focused back tracing attack to improve its attack success rate. Furthermore, the ProbR protocol distributes only one fake packet at a time. As a result, the adversary is not effectively distracted from the real packet routes and short safety period is achieved by the ProbR protocol. The safety period of Pha protocol is significantly lower because the protocol employs a simple routing algorithm with short and fixed routes. The adversary is capable of successfully back tracing the routing paths of the Pha within a short time. For all the protocols, the privacy performance improves with the increase in source-sink distance because the adversary back tracing attack becomes more complicated with longer routing paths. Figure 5b shows the privacy performance of the protocols at a source-sink distance of 40 hops against varied source packet generation rate. The protocols offer lower safety period as the source packet rate increases. The main reason for the reduced safety period