## 5 Robustness Results and Analysis
### Comparing BiRep with the State-of-the-Art  
Finally, we compare BiRep with other reputation schemes described in Section 2. For FBIDM [10], the overall conclusion was that for the Prophet routing protocol, the false-positive ratio was kept between 2% and 5%. The percentage of malicious nodes detected  
Figure 11: Comparison of detection ratio for good nodes and false-positive ratio for good nodes for Prophet, with 20% of malicious nodes to test the robustness of scenarios with different node numbers and profiles.  
Figure 12: Comparison of delivery ratio for good nodes, overhead ratio for good nodes, and average latency for good nodes for Prophet to test the robustness of scenarios with different node numbers and profiles.  
was around 80% at best. Although a straight comparison cannot be made, as neither the simulator nor the simulation parameters are the same, the scenario with 50 cars is similar enough to try and make a fair comparison. Figure 11 shows that for the Prophet protocol, the detection ratio is set around 70-80% and 0% for the false-positive ratio. The results are not much different, but BiRep has the benefit of not having a single point of failure, as it is not a centralized system, and nodes can make decisions by themselves.  
For MUTON [13], the simulation results are better: 1-2% false-positive ratio and 95% detection ratio. This scheme has 10-30% of malicious nodes in the simulation. For that scenario, again comparing with the 50 nodes scenario for 20% of malicious nodes, BiRep has a 0% false-positive ratio and at least 80% detection ratio. MUTON has a better detection ratio but problems associated with having a centralized detection scheme.  
Compared with the MDS in [14], for Prophet, the MDS scheme has a detection ratio higher than 90%, reaching 97%, and 0% false-positives. To make a fair comparison, as the simulator used in [14] is the same in this work, and the authors provided the simulation settings, a test was made. The detection scheme of BiRep was applied but using the simulation settings of [14]. Actions started being applied at 10,000 s, as in [14], and using the Disconnect Action scheme. The results are presented in Figure 13.  
As the simulation results prove, at least the detection scheme part of BiRep works very well, outperforming the results of MDS [14] for black-hole nodes, and for the most part, reaching a perfect result in terms of detection.  
For [16], again, only the Prophet protocol is analyzed. A fair comparison cannot be made, as the simulator and movement models are not the same. The detection rate for different mobility schemes is 85-100% and the false-positive rate is around 2%, in the best case. The results, in general, are worse than those for BiRep. When comparing, BiRep does stand out as a good option. However, to make a completely fair comparison, further simulations should be made. That would require access to the other works' source code, so it is left for further work.  
Our solution also assumes that nodes do not change behavior, so there are no grey-hole nodes and nodes do not collude. Even when looking only at a scenario where black-hole nodes do not change behavior and do not collude, there are still flaws. If direct delivery were to be used, all nodes would be considered malicious as they are always the source of the messages they carried. Nevertheless, this can also be considered a nonproblem as Direct Delivery performance is not affected by black-hole nodes. Table 4 presents a comparison between BiRep and state-of-the-art schemes regarding false positive and detection ratios.  
Figure 13: Detection ratio for good nodes and false-positive ratio for good nodes for Prophet with simulation settings of [14] and BiRep.