# ATWin: An Improved and Detailed Startup Model of TTP/C
## 3 The Proposed Startup Model ATWin
### The Startup Model ATWin
& Fixed duration \(\Delta_{PSP}\) \\ \cline{2-3}  & \(CS_{3}\) & Stops local lock; stops receiver; transits into \(LISTEN_{1}\) state unconditionally. & 0 \\ \cline{2-3}  & \(CS_{4}\) & Sets the value of local clock; starts local clock; sets the c-state; sets node timing parameters; sends a cold-start frame; waits for the end of ATW. After the end of ATW, the node transits into \(CS_{5}\) state. & Fixed duration \(\Delta_{window}\) \\ \cline{2-3}  & \(CS_{5}\) & Performs the routine transactions of the PRP phase; waits for the end of the PRP phase. After the end of PRP phase, the nodes transit into \(CS_{1}\) state. & Fixed duration \(\Delta_{PRP}\) \\ \hline \multirow{8}{*}{_SUBBCS_} & Is a synchronized cold-start state. Sets the value of local clock to 0; starts local clock; starts receiver; starts channel listening. If the node exceeds the max entry limit of cold-start times, then the node transits into \(LISTEN_{1}\) state. If the node detects channel activities before the expired time of startup timeout timer, then the node transits into \(LISTEN_{2}\) state. & \\ \cline{1-1} \cline{2-3}  & \(SUBCS\) & Is a synchronized cold-start state. Sets the value of local clock to 0; starts local clock; starts receiver; starts channel listening. If the node exceeds the max entry limit of cold-start times, then the node transits into \(LISTEN_{1}\) state. If the node detects channel activities before the expired time of startup timeout timer, then the node transits into \(LISTEN_{2}\) state. & Variable duration with the upper bound \(\Delta_{cellular}\)  
There is no contention-detecting strategy in the standard startup model. If the type of contention scenario is C1, the ATWin model cannot determine whether there is contention occurring, marked as pseudo-contention. If the type of contention scenario is C2 or C3, the ATWin model can detect contention that has occurred. If the type of contention scenario is C1 or C2, the receiving node can receive one valid cold-start frame in both scenarios. In these two contention scenarios, both the proposed model and the standard model perform the same operation, discarding the first cold-start frame and successfully starting in the next round. The difference is that our ATWin model can detect contention in the C2 scenario, while the standard model can not. If the type of contention scenario is C3, the receiving node receives overlapping frames. After discarding the invalid frames, our startup model starts successfully in the next round, but the standard startup model must re-enter the listening state and wait for a valid cold-start frame. In a C3-type contention scenario, our startup model saves at least time of one startup cycle, compared to the standard startup model. The differences in detecting and eliminating contention between the standard startup model and our ATWin startup model are summarized in Table 4.  
In summary, the contention-detecting strategy in the ATWin model refines the condition of dropping frame and clarifies the contention scenario where there is no need to discard the frame. Specifically, ATWin can reduce the startup time in the C3-type contention scenario, saving the system at least one TDMA cycle of time. In the other two contention scenarios, our model does not save time compared to the standard startup model.