## 5 Simulation Setup and Result Analysis
### End-to-End Delay of Packets Using MCMP, MMSPEED, SPIN, EAP and PT  
The end-to-end delay is one of the most significant parameters for improving the QoS for WSNs. Many WSN applications require an end-to-end delay for time-sensitive data. However, this delay is difficult to bound for event-driven WSNs, in which the sensor nodes produce and broadcast data only when an event of interest occurs, thus creating a variable traffic load. The end-to-end delay is also tightly linked to other factors, such as the network capacity, energy, and the relative location of the sensors and sink nodes. In real-time applications, packets are dropped when they are transmitted with excessive delays. Figure 9 presents the end-to-end delays of PT, MCMP, MMSPEED, SPIN and EAP.  
PT produces a lower end-to-end delay than do the other competing protocols, and the end-to-end delay and node density are inversely proportional in the PT algorithm, which aids in finding alternative paths to the destination. PT also exhibits higher route maintenance than do SPIN, MCMP, MMSPEED, and EAP due to the efficient use of alternative paths, which helps produce low end-to-end delays even with mobile nodes.  
Successful Packet Delivery Rate and Energy Utilization Efficiency of O-MAC and Competing Hybrid Protocols  
In this section, we analyze and evaluate the performance of the O-MAC and other competing hybrid (cross-layered) protocols: ECLP, CL-MAC, P-MAC, RMAC, MAC-CROSS, XLM and EOA. We created a mobility scenario with 80% of the nodes as mobile nodes and monitored the activities of all four regions. There is one problem noticed in the mobile scenario, which occurs when the nodes occasionally exceed the transmission range. Thus, the nodes require the dynamic sink (head node) to reduce its energy consumption; in our case, we use a DON to handle this issue.  
We used a node speed varying from 0 to 18 m/s. Figure 10 illustrates that O-MAC outperforms the other competing protocols in terms of the successful delivery of packets. The O-MAC protocol has a higher packet delivery rate because of its efficient use of several features, such as semi-synchronization, the anycast methodology, randomization, the ODFF, automatic buffering, and determination of a  
Figure 9: End-to-end delay for PT, SPIN, MCMP, MMSPEED and EAP.  
node's information prior to leaving the communication; whereas the competing hybrid protocols lack these features.  
The performance of O-MAC and competing hybrid MAC protocols were analyzed in highly congested networks. O-MAC outperforms all competing hybrid protocols. The success rates of the competing protocols decrease when the simulation time increases. Figure 11 illustrates that O-MAC consumes less energy than the other competing MAC protocols. The reason for the lower energy consumption is the use of a short preamble without incorporating the address with the preamble. The short preamble reduces the time and energy consumption of each node in the network. In addition, O-MAC has the support of the PT model, which includes two important features: the packet generation rate and pheromone sensitivity to help find a reliable and robust path for forwarding the packets over single and multiple links, which leads to lower energy consumption and increased efficiency.  
Figure 11: Energy consumption of O-MAC and other competing hybrid MAC protocols with 80% mobile nodes.  
Figure 10: Successful packet delivery rates of O-MAC and other competing hybrid MAC protocols with 80% mobile nodes.