# ATWin: An Improved and Detailed Startup Model of TTP/C
## 5 Summary and Prospect  
The core issues of the TTP/C startup task are how to eliminate contention during the startup phase and how to determine the upper bound of the system startup time. Through analyzing the standard startup model defined by AS6003, it was found that the standard startup model currently has the following limitations. First, the standard startup model is described as a top-level design in the standard of the SAE and therefore lacks the necessary details for practical implementation. It is difficult to formally prove the effectiveness of the standard startup model for a TTP/C cluster with any number of nodes as well as to determine the formal upper bound of its startup time. Secondly, the standard startup model defined employs a forcible frame-dropping strategy to eliminate contention. Without an effective contention-detecting strategy, it poses a negative effect on startup time in cases where contention does not occur.  
To address these limitations, this paper proposed an improved and detailed startup model ATWin with a contention-detecting method to synchronize a TTP/C cluster. The proposed model supplements the undefined details of the standard startup model in AS6003, thereby bridging the gap between the top-level standard and its implementation. Our ATWin is an implementable startup model for a TTP/C cluster, and we have opened the source code of the proposed model to make it more useful. An arrival time window and a contention flag are introduced to the model based on the standard startup model in AS6003 to achieve contention detection. Unlike the standard startup model, the ATWin model  
Figure 9: The upper bound of the clique-detecting time.  
addresses specific contention scenarios by discriminating different types of contentions, rather than roughly discarding all first cold-start frames. The detection strategy added in ATWin can avoid unconditionally forcing the first startup frame to be discarded in all contention scenarios. In C3-type contention scenarios, ATWin can accelerate startup by reusing the frame, saving the system at least one TDMA cycle of time to start. However, ATWin cannot reduce startup time of the system at the worst case. The lower time bound of the proposed arrival time window that can meet the requirements of system startup is also given. At last, this paper formally proves that the ATWin startup model can complete contention elimination during the startup phase, and it derives a conclusion that the maximal startup time of our model is no more than \(3n\Delta_{slot}\), thereby proving the effectiveness of our model.  
However, TTP/C has high fault-tolerance requirements during startup. Formal analysis of the ATWin model under the fault hypothesis has not yet been considered in this paper. This remains an important area for future work.  
Conceptualization, B.Y.; Methodology, T.Y.; Validation, B.Y.; Resources, X.S.; Writing--review & editing, T.Y.; Supervision, C.T. All authors have read and agreed to the published version of the manuscript.  
This study is partially supported by National Natural Science Foundation of China (62176016, 72274127), National Key R&D Program of China (No. 2021 YFB2104800), Guizhou Province Science and Technology Project: Research and Demonstration of Sci. & Tech Big Data Mining Technology Based on Knowledge Graph (supported by Qiankehe[2021] General 382), Teaching Reform Project of Beihang University in 2020: Standardized Teaching and Intelligent Analysis System Construction for Production Practice, and Capital Health Development Research Project (2022-2-2013).  
Not applicable.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the writing of the manuscript; or in the decision to publish the results.