# Task Migration with Partitioning for Load Balancing in Collaborative Edge Computing
## 4 Simulation Results and Discussion
As shown in Figure 5, depending on the load balancing among MECSs, the task completion rates within the delay constraints had a high rate. Thus, if the task execution delay is prolonged, service interruption occurs when receiving its result. To receive the result without service interruption, the vehicle must obtain the result quickly before it moves out of the coverage of the MECS to which the task is offloaded. If the load balancing among MECSs is appropriate, the task execution delay will be reduced, and the reliability rate will be high. Therefore, the _Proposed_ method had the highest rate, and the _No migration_ method had the lowest rate in terms of the task completion rates within the delay constraints and task reliability rates. Therefore, it was better to perform migration than not, and migration with partitioning performed better than full migration. Therefore, in this study, we considered task migration with partitioning. Figure 4: Load variance among MECSs of the three methods; (**a**) vehicle arrival rate = 0.3; (**b**) vehicle arrival rate = 0.6; (**c**) vehicle arrival rate = 0.9. Figure 5: Task completion rates of the three methods. To verify the performance of our proposed method, we compared it with four other methods: _IPSO_[20], _Nearest_, _Least_ and _Random_. _IPSO_ aims to minimize the service failure probability by considering task execution delay. It is a method of migrating tasks to MECSs that meet the latency constraint of the subtasks. _IPSO_ defines the workload of the subtasks as the ratio of the sum of the required CPU cycles to the sum of its input and output data. _Nearest_ is a method of migrating tasks in overloaded MECSs to the nearest MECS among underloaded MECSs. _Least_ is a method of migrating tasks in overloaded MECSs to the least loaded MECS among underloaded MECSs. _Random_ is a method of migrating tasks in overloaded MECSs to randomly selected MECSs among underloaded MECSs. The task completion rates within the delay constraints under different values of delay constraints are shown in Figure 7 for a vehicle arrival rate of 0.6. _Proposed_ achieved the highest completion rate for different values of the delay constraint, a value of approximately 35-60% higher than that of other methods. The task reliability rate under different values of mobility speed of vehicles is shown in Figure 8 for a vehicle arrival rate of 0.6. Service interruption occurs when the vehicle can travel out of the coverage of the MECS that is offloaded during a service session, which significantly increases the total service latency. We observed that _Proposed_ achieved the highest task reliability rate for different values of mobility speed, approximately 20-51% higher than that of other methods. A comparison of the environment with high and low speeds indicated differences of approximately 8% for _Proposed_, 11% for _IPSO_, 15% for _Nearest_, 17% for _Least_, and 13% for _Random_. Under conditions with different delay constraints and mobility speed, _Proposed_ performed better than that of others by optimizing the load balancing, which reduces the task execution delay. Therefore, we conducted the experiment by setting the delay constraints to 0.1-0.6 s and the mobility speed to 1-30 m/s. Figure 6: Task reliability rates of the three methods. Figure 7: Task completion rates for delay constraints. Figure 9 shows the load variance among the MECSs when the arrival rates were 0.3, 0.6 and 0.9. In _Proposed_, the set of subtasks in the task was migrated to one or more target MECSs depending on the load difference. In _Nearest_ and _Random_, the set of subtasks in the task was migrated to the target MECSs based on distance and randomness. In _Least_, the set of subtasks in the task is migrated to the least loaded MECS, which indicated a scenario in which the least loaded MECS was concentrated. Therefore, depending on which MECS was selected as the target MECS, the loads of the MECSs varied. In _IPSO_, the set of subtasks was migrated based on delay constraint.