# Design and Analysis of a Low Latency Deterministic Network MAC for Wireless Sensor Networks
## 7 Simulation Results
However, it remains constant after certain offered loads. The significant changes in the graph are due to the presence of different numbers of nodes per shared slot. We observe that the maximum throughput is achieved as 780 bits per second, when only 10 nodes per shared slots are considered and the payload is 100 bytes. However, the throughput remains constant after the offered load is 800 bytes irrespective of the number of nodes. The close agreement between the simulation and analytical results shows the accuracy of the proposed analytical model though there is little difference due to the assumptions. From Figure 8, it is shown that throughput decreases with respect to the number of nodes attached to the shared slot with or without the hidden terminal problem considering the  
Figure 5: packet success probability with and without hidden nodes. Figure 6: Comparison of our protocol with IEEE 802.15.4e. offered load as 200 bits/node. As shown in Figure 9, we compare the IEEE 802.15.4e protocol with ours. It is observed that the throughput of our protocol is significantly higher than the standard when we consider only 20 nodes per shared slot. This happens since our carrier sensing mechanism sends the nodes to backoff when they access the channel in the same time slot. Hence, any other node can access the channel successfully. Figure 8: Throughput with and without hidden nodes. Figure 7: Validation of throughput for different offered loads. Figure 12 shows the result of transmission delay for a data payload of 100 bytes. It is observed that the transmission delay increases with the increase in the offered loads irrespective of the number of nodes accessing in a shared slot. As shown in Figure 13, the transmission delay in our protocol is compared with the IEEE 802.15.4e standard under the ideal channel condition. It is observed that the transmission delay of our protocol is significantly less as compared to the IEEE 802.15.4e standard. In Figure 14, we take the number of superframes along the \(X\) axis and get the expected number of retransmission slots along the \(Y\) axis. It is observed that the required average number of retransmission slots is nearly equal to our predicted value when 10 superframes and 20 nodes per shared slot are considered. However, the predicted number of retransmission slots is higher than the average number of retransmission slots when more superframes are considered. Figure 11: Comparison of the energy consumption of our protocol with the IEEE 802.15.4e standard. Figure 12: Validation of transmission delay for different offered loads. Figure 15 shows the result of reliability for different offered loads. We find that the radiabilities decrease with respect to the offered loads and irrespective of the number of nodes accessing in a shared slot. In Figure 16, we compare the reliability of the IEEE 802.15.4e standard with ours under the ideal channel condition. It is observed that the reliability of our protocol is significantly higher than the IEEE 802.15.4e standard. Table 3 shows the summarization of the statistical results for transmission success probability, throughput, delay, energy consumption and reliability. Figure 14: Optimal number of retransmission slots for different numbers of superframes. Figure 13: Comparison of the transmission delay of our protocol with the IEEE 802.15.4e standard. Figure 4:0 Comparison of reliability of our protocol with the IEEE 802.15.4e standard.