# A Distributed Token Passing Protocol for Time Constrained Data Gathering in VANETs
## 3 Proposed Approach
### Phase I: Token Processing
Figure 7: Normalised gathered information comparisons among the proposed TT and alternative approaches for Scenario 1 and different ND values. ## 5 Conclusions

This paper deals with the proposal of a novel distributed protocol for information gathering and sharing within a VANET, by adopting D2D communications among vehicles. In particular, we characterise the case study in terms of a time constrained protocol, where the objective function is represented by the collected information, which allows the system to be context-aware, within a constrained time interval. In order to afford this problem, we propose a heuristic sub-optimal approach, i.e., TT protocol. In addition to this, it has been designed in terms of packet format, while the related sequence diagrams have been properly characterised. By resorting to accurate numerical simulations in a couple of scenarios, we validated the effectiveness of the proposed approach in terms of token recovering probability and the collected information by further comparing it with the optimal solution and an alternative one already proposed in the literature. As a consequence, the TT approach can be successfully applied for traffic monitoring and control applications expected in a typical smart city scenario. Conceptualization, F.C. ; Data curation, F.N. ; Funding acquisition, R.F. ; Investigation, L.P. and C.B. ; Methodology, F.C. ; Project administration, L.P.; Software, F.N. ; Supervision, R.F. Figure 10: Collection probability comparisons among the proposed TT and alternative approaches for Scenario 2 and different ND values in the presence also of a low mobility pattern. Figure 9: Normalised gathered information comparisons among the proposed TT and alternative approaches for Scenario 2 and different ND values in the presence also of a low mobility pattern. **Funding:** This research was funded in part by he project \"GAUChO--A Green Adaptive Fog Computing and Networking Architecture\" funded by Progetti di Ricerca di Rilevante Interesse Nazionale (PRIN) Bando 2015--Grant 2015 YYKH4W_004. **Conflicts of Interest:** The authors declare no conflict of interest.The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results

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