# A Novel IEEE 802.15.4e DSME MAC for Wireless Sensor Networks
## 6 Simulation  
In this section, we validate and evaluate our models by using OMNeT++ [35] simulator. We perform simulations to compare our proposed schemes with IEEE 802.15.4e. In our simulation, star topology is considered, where each device is deployed randomly around the coordinator. Our work is compared with the IEEE 802.15.4e standard for successful transmission, throughput, reliability, average network delay and energy consumption taking poisson arrival rate. The simulation parameters given in Table 2 are set as per the IEEE 802.15.4e standard. The simulation is performed with 50 runs and the results are given taking average of those 50 runs. As shown in Figure 6, different number of devices are considered to evaluate the corresponding packet success probability. It is observed that the packet success probability decreases as the number of devices attached to a coordinator increases irrespective of the beacon order. When the data payload of 100 bytes and 500 number of devices are considered, the success probability is 0.96, if the beacon order is 10. But, the probability is 0.85, 0.70 and 0.47 for the beacon order 9, 8 and 7, respectively. The difference between the simulation and analytical results varies little due to the distribution of devices to different superframes. The number of associated devices to one CAP decreases by increasing the beacon order. As shown in Figure 7, our work is compared with the IEEE 802.15.4e standard based on the simulation results for different values of beacon order and superframe order. It is observed that the packet success probability of our work is higher as compared to the IEEE 802.15.4e. Figure 8, demonstrates the throughput corresponding to the number of devices. It is observed that the throughput decreases as the number of devices attached to a coordinator increases irrespective of the \begin{table}
\begin{tabular}{c c} \hline
**Parameters** & **Value** \\ \hline Radio band & 2.4 GHz \\ Channel bandwidth & 250 kbps \\ Carrier sense sensitivity & \(-85\) dBm \\ Channel number & 11\(\sim\)26 \\ Beacon interval & \(15.6\times 2^{4}\) ms \\ Unit backoff period & 20 symbol \\ PHY overhead & 6 byte \\ MAC overhead & 3 byte \\ Transmission current consumption & 9.1 mA \\ Receiving current consumption & 5.9 mA \\ Turnaround current consumption & 7.5 mA \\ Sleep current consumption & 0.001 mA \\ \hline \end{tabular}
\end{table} 
Table 2: Simulation parameters. Figure 6: Validation of packet success probability for different beacon order. beacon order. When the data payload of 100 bytes and five hundred number of devices are considered, the throughput is 0.27, if the beacon order is 10. We compare our work with the IEEE 802.15.4e standard for equal number of beacon and superframe order as shown in Figure 9. It is found that the throughput of our scheme is higher than the standard except when the number of devices are less than 15. This happens as we keep two idle slots between CCA1 and CCA2 in our proposed scheme to avoid the channel busy due to acknowledgement. Also, we find that the analytical result well match with the simulation one. Figure 8: Validation of throughput for different beacon order. Figure 7: Comparison of packet success probability of our proposed scheme with the IEEE 802.15.4e standard. The reliability of data transmission with respect to different numbers of devices is compared as shown in Figure 10. It is observed that the reliability decreases as the number of devices attached to a coordinator increases irrespective of the beacon order. When the data payload of 100 bytes and 500 number of devices are considered, the reliability becomes 0.99 when beacon order is 10. However, it decreases when the value of beacon order becomes 9, 8 and 7. As shown in Figure 11, our work is fairly compared with the IEEE 802.15.4e standard maintaining equal beacon and superframe order. It is observed that the reliability of our scheme is higher and the simulation result matches with the analytic one. Figure 12, demonstrates the delay corresponding to the number of devices.