# ATWin: An Improved and Detailed Startup Model of TTP/C
## 2 Background Work and Literature Review
### The Standard Startup Model in AS6003
If it receives an integrated frame or a cold-start frame during the waiting period, it enters the LISTEN state again. Otherwise the node attempts to send the cold-start frame again and enters the cold-start state. **B. The contention eliminating strategy in AS6003**  
When it comes to handling the contention, the standard startup model in AS6003 only uses the explicit sematic-full start frame as the initial signal of the startup, and it adopts a priority-based back-off strategy to handle the contention that may rise from concurrent \begin{table}
\begin{tabular}{l l} \hline \hline
**Symbols** & **Annotations** \\ \hline \(\Delta_{TDMA}\) & Duration of a TDMA round \\ \hline \(\Delta_{\mathit{slot}_{j}}\) & Duration of a slot for Node \(j\) \\ \hline \(\Delta_{\mathit{PSP}}\) & Duration of the PSP phase of a slot \\ \hline \(\Delta_{\mathit{TP}}\) & Duration of the TP phase of a slot \\ \hline \(\Delta_{\mathit{PRP}}\) & Duration of the PRP phase of a slot \\ \hline \(\Delta_{\mathit{startup}}^{i}\) & Timeout value of the startup timeout timer of Node \(i\) \\ \hline \(\Delta_{\mathit{listen}}^{i}\) & Timeout value of the listening timeout timer of Node \(i\) \\ \hline \(\Delta_{\mathit{coldstart}}^{i}\) & Timeout value of the cold-start timeout timer of Node \(i\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Some symbol definitions of TTP/C. Figure 2: The state transition diagram for the standard startup process in AS6003. access to the shared communication media when synchronization of the system has not been achieved. In view of the multi-clique problem, the standard startup model forces the start nodes to disconnect the channel at the first startup and the receiving nodes to drop the first valid cold-start frames, in order to prevent any divergence during the startup phase. The sequence diagram in Figure 3 illustrates how the standard startup model eliminates contentions. Assume that concurrent startup occurs between Node \(i\) and \(j\), the logical contention occurs between Node \(m\) and \(n\), and the bus contention occurs at Node \(k\). Node \(i\) and node \(j\) fail to detect a clique after a cold-start cycle, and then, they re-enter the LISTEN state. Node \(m\) and \(n\) are required to discard the first cold-start frame and re-enter the COLDSTART state again. Node \(k\) enters the LISTEN state directly due to bus contention. In the next round of startup, Node \(i\) obtains the right to send the first frame due to the precise timer timeout value and ensures that the subsequent nodes receive the cold-startup frame from node \(i\) before the timer expires. Node \(k\) receives valid cold-start frames during this round of startup, but it is not permitted to join the system until the next TDMA round. Even if all receiving nodes receive a valid cold-start frame, they cannot determine whether to enter the SYNC state directly. Each node must run the clique detection algorithm at the sending slot to verify whether it is in the majority clique of the cluster. From Figure 3, it can be seen that in AS6003, all the first valid frames are intentionally discarded during the startup phase to force the nodes to re-enter the listening state. This strategy is used to avoid the inconsistent judgment of the concurrency state. However, this strategy may result in an increase in the time required for nodes to reach the SYN state in certain situations, rendering the analysis of the upper bound of the startup time more challenging. If all nodes that open their receivers before channel activity can make a consistent judgment for the contention state within a fixed time, there is no need to forcibly discard all of the first valid frame. Figure 3: The sequence diagram of contention eliminating in the standard startup model. The black box represents the sending frame, while the gray box represents the receiving frame in this figure.