## 5 Proposed Adaptive Beaconing System
### Characterization of Node Distribution
#### 5.2.3 Defuzzification
This figure shows that the average waiting time for HACEAB is smaller than that for all other protocols for all densities. This is because HACEAB monitors the channel carefully and adapts intelligently according to its status. Figure 19 shows that HACEAB maintains a smaller delay than the other protocols, while the other protocols have almost the same performance pattern for channel waiting time. In Figure 20, we can see clearly that HACEAB achieves a much higher level of awareness than the other protocols, and it improves as the density increases (more scalable than the other protocols). Figure 17: Average number of neighbors in an urban environment. Figure 18: Average waiting time in a highway environment. #### 6.2.2 Urban Environment

Figure 21 proves that HACEAB maintains a smaller waiting time than the other protocols for all densities. This means that HACEAB uses the channel more efficiently than the other protocols. Figure 22 illustrates that a fixed beaconing rate causes a high delay that increases exponentially due to a high processing delay which increases as the number of packets becomes larger. The delay for HACEAB, shown in Figure 22, is closer to that of BRAIN-F for 10 and 50 vehicles and lower than that of all other protocols for 100, 150, and 200 vehicles. Figure 23 shows that the cooperative awareness of the fixed beaconing rate becomes relatively worse as the number of vehicles increases. The reason behind that is the increase in the number of collisions, which make other vehicles unable to receive packets. In this figure, we can see that HACEAB achieves a comparable level of cooperative awareness to BRAIN-F for 10 and 50 vehicles, with a slight improvement for 100 and 150 vehicles, and a noticeable improvement for 200 vehicles. Figure 19: Total delay in a highway environment. Figure 20: Average number of neighbors in a highway environment. Figure 11:0 Average number of neighbors in an urban environment. Figure 11:1 Total delay in an urban environment. HACEAB exhibits superior performance compared to other protocols due to its careful consideration of crucial factors, including channel conditions, traffic situations, and link quality. This capability allows HACEAB to dynamically adjust its beaconing rate, effectively addressing essential aspects for efficient operation. Moreover, HACEAB decides to adapt its beaconing frequency and uses the most suitable factors based on different scenarios in a novel way. ### Performance of HACEAB with Transmission Power Adaptation

Here, HACEAB's performance with power adaptation (referred to as power on) is evaluated and compared to its performance without power adaptation (referred to as power off). #### 6.3.1 Highway Environment

Figure 24 shows that the average waiting time of HACEAB when power adaptation is on is better than when power adaptation is off for all densities. This is because HACEAB decreases the transmission power in dense conditions (when the local density is larger than the density threshold) or whenever it detects that the vehicle distribution is more evenly spaced (\(Q<1\)). Reducing transmission power in these conditions causes more vehicles to be excluded, thus alleviating the load on the channel. In Figure 25, we notice that the packet delay, when the transmission power adaptation is on, is slightly higher than when it is off. This is expected since HACEAB increases the transmission power according to the vehicle distribution, which causes more vehicles to be covered. Consequently, the number of packets that are processed locally increases. A smart protocol is the one that increases the transmission power to improve cooperative awareness when the channel is freer to accommodate more vehicles and vice versa; this is what HACEAB does. In Figure 26, we can obviously see that goal has been accomplished. Transmission power adaptation in HACEAB increases cooperative awareness. Figure 11:2 Average waiting time in a highway environment.