## 6 Evaluation
### Evaluation Results  
#### 6.2.1 Number of Packet Occurrences  
We compared the proposed collision avoidance methods (AR-Proposal, RR-Proposal) of both the autonomous response-type and the request-response-type stray node detection protocols for a case where collision avoidance relies on CSMA/CA only. In order to examine how much packet transmission attempts are distributed during the stray node detection processing in each collision avoidance method, we measured the number of packets that arose at each 10-ms interval in the case where the number of nodes was 15. The result is shown in Figure 13. Figure 13a,b show the number of packets that arose in the autonomous response-type stray node detection. Figure 13a shows that  
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Stray Node Detection Type** & **Evaluated Protocol** & **Processing Logic** & **Collision Avoidance Method** & **Medium Access Control** & **Abbreviation** \\ \hline \multirow{3}{*}{Autonomous response type} & Proposed protocol & \multirow{3}{*}{Refer to Section 4.1.1} & Used (refer to Section 4.1.2) & \multirow{3}{*}{AR-Proposal} \\ \cline{2-3} \cline{5-6}  & Compared protocol & & & Not used & \multirow{3}{*}{AR-Basic} \\ \hline \multirow{3}{*}{Request response type} & Proposed protocol & \multirow{3}{*}{Refer to Section 4.2.1} & Used (refer to Section 4.2.2) & \multirow{3}{*}{CSMA/CA} \\ \cline{2-3} \cline{5-6}  & Compared protocol & & & & \\ \cline{1-1} \cline{2-3} \cline{5-6}  & Compared protocol & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Stray node detection protocols evaluated and their abbreviations.  
packet transmission attempts concentrated within the first three seconds from the start of the stray node detection processing. In contrast, Figure 13b shows that a small number of packets arose over a period of 7 s. Figure 13c,d show the number of packets that arose in the request-response-type stray node detection. Figure 13 c indicates that more than 24 packets arose simultaneously immediately after the start of the stray node detection processing. This bursty packet traffic occurred because each node that had received a REQUEST message returned a REPLY message and forwarded the REQUEST message almost simultaneously. In Figure 13d, there were no concentrations of packet transmission attempts. In any of these cases, packet transmission attempts were more distributed when the proposed protocols were used. The bursty traffic that occurred when the compared protocols were used resulted in packet loss.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Item** & **Value** \\ \hline Simulation time & 2000 s \\ Number of nodes & 5, 10, 15 \\ Node velocity & 1–5 km/h \\ Stray node detection distance (r) & 20 m \\ Transmission power & 0.7 mW \\ Mobility model & Group Based Random Waypoint \\ Leave probability (R\({}_{\text{D}}\)) & 0.001 \\ Frequency & 150 kHz \\ Propagation delay time (8d) & 100 ms \\ Random time & 0–100 ms \\ Self Time & 500 ms \\ Transmission rate & 62.5 kbps \\ Payload length & 24 Bytes \\ Transmission interval (T) & 10 s \\ Timeout & 9 s \\ Hop limit & 3 \\ Slot time & 8.19 ms \\ SIFS & 9.1 ms \\ \hline \hline \end{tabular}
\end{table}
Table 4: Simulation conditions.  
Figure 13: _Cont._