# FOXS-GSC--Fast Offset Xpath Service with HexagonS Communication
## 4 FOXS-GSC Performance Evaluation
### Traffic Efficiency Evaluation
#### 4.3.2 Results  
Figure 10 shows the values and \(BASE\) related percentage of all metrics for the implemented solutions regarding traffic efficiency. For this evaluation, FOXS-GSC was compared with the DSP, PAN1, PAN3, and CHIMERA solutions. To evaluate FOXS-GSC in scenarios with different levels of coverage, we used 1, 23, and 50 RSUs, with 50 RSUs providing full scenario coverage. PAN1, PAN3, and CHIMERA, all used 50 RSUs to provide full coverage, as this was assumed in the original proposals. Figure 10: Traffic efficiency comparison results: (**a**) stopped time; (**b**) average speed; (**c**) traveled time; (**d**) traveled distance; (**e**) fuel consumption; (**f**) CO\({}_{2}\) emissions. Compared with the BASE results (see Figure 10a), the solutions from the literature reduced the stopped time metric by 16.17% (PAN1), 13.68% (PAN3), and 21.36% (CHIMERA), while the proposed FOXS-GSC protocol achieved a reduction of 22.01% with one RSU, 30.46% with 23 RSUs, and 39.14% with 50 RSUs. These results are primarily a reflection of the higher average speed metric achieved with FOXS-GSC (see Figure 10b), resulting in its reaching better performance compared to the other evaluated solutions even in the scenario with only one RSU. In the scenarios with 1, 50, and 23 RSUs, FOXS-GSC increased the average speed by 9.04%, 13.44%, 17.47%, respectively. These results are due to the effectiveness of the road classification approach that FOXS-GSC implements and the probabilistic mechanism it uses to choose one of \(K\) alternative routes. It should be remarked that the DSP solution increased stopped time by 90% and reduced the average speed metric by 18% compared to \(BASE\). This occurs because the routing algorithm that DSP implements simply uses the shortest path, resulting in its forwarding all of the vehicles to the same road, creating a new congestion point. The other evaluated solutions compute a new route based on the road conditions when necessary, thereby avoiding this problem. Considering the average speed metric, the results for the PAN1 solution are 6.5% faster than BASE, while PAN3 achieves an increase of 5.1%. In this case, PAN3 has worse results than PAN1 because it computes three alternative routes and chooses one at random. However, in this scenario the second-best and third-best routes may have very different traffic jam conditions and route sizes compared to the best route considering the geography of this particular city map. FOXS-GSC is able to avoid this problem by choosing an alternative route using the route size factor parameter and the probability mechanism to reduce the chance of choosing a poor route. The travel time metric (see Figure 10c) presents similar behavior. FOXS-GSC more efficiently manages urban traffic, decreasing the travel time in the scenarios with 1, 23, and 50 RSUs by 12.14%, 17.34%, and 22.63%, respectively. With 50 RSUs, the results for FOX-GSC were twice as good as tose for CHIMERA, which reduced travel time by 11.73% when compared to the \(BASE\) solution. Considering the traveled distance metric (see Figure 10d), only the DSP solution reduced the distance traveled compared to \(BASE\) (2.39%). This is due to DSP always choosing the shortest path, unlike other solutions, which use the traffic conditions when computing a new route. Regarding FOXS-GSC, in the scenarios with 1, 23, and 50 RSUs the alternative routes computed are not longer than the original ones (0.99%, 1.28%, and 0.39%, respectively). This is due to the route size factor parameter implemented by FOXS-GSC, which manages the maximum length of alternative routes. Analyzing the fuel and CO\({}_{2}\) emission consumption metrics (Figure 10e,f respectively), it can be noted that both of these metrics are directly influenced by the travel time, stopped time, and distance traveled. In analyzing these metrics, it is found that in the scenario with one RSU FOXS-GSC is able to reduce fuel consumption almost half and CO\({}_{2}\) emissions by 4.25% when compared with second-best solution (CHIMERA, with 2.68%).