# Mobile Autonomous Sensing Unit (MASU): A Framework That Supports Distributed Pervasive Data Sensing
## 4 MASU Evaluation Using Simulations
### Simulation Results
#### 4.2.1 Considering Different Network Infrastructures  
For this first set of simulations we used the RandomWalk mobility pattern and evaluated the performance of the MASU framework for various network infrastructures: AP, T2T and MANET. As shown in Figure 8, for AP and T2T networks in the Dynamic Centralized and the Distributed approaches, the average presence of the Producer increases, when no Control Tier was active. Nevertheless, in the Fixed Centralized method the results for both types of networks are not good enough when there is less than 60 and 70 of average Producer presence, respectively. Notice that the results obtained for MANETs are always the same, independently of the approach followed.  
These results show that the Dynamic Centralized and Distributed approaches considered in the MASU framework allow one to achieve significant improvements in comparison to a Fixed Centralized approach. Next we evaluate the cost required for such improvements, in terms of the number of messages sent by the algorithms used for dynamic role Selection and Activation.  
For this evaluation, we considered the four (i.e., Unit Detection, Device Information, Election and Consensus messages) of the six types of control messages defined by the MASU framework as well as the particular messages required by the routing protocol in MANET networks (routing messages). However, in the Device Information messages, we did not consider the messages required for hardware monitoring because we cannot measure changes of the hardware components of the devices in the simulator. We only considered the Device Information messages sent after a role Selection and Activation process in the Sensing and/or in the Control Tiers takes place. Thus, we only  
Figure 8: Performance of the Control Tier for different network infrastructures.  
included the messages sent by new network nodes that are unknown for the new Manager selected. Therefore, the number of Device Information messages is associated with the number of nodes that are concurrently active when a new Manager is selected.  
Figure 9 shows a comparison of the number of messages required for the Dynamic Selection and Activation of roles in Fixed Centralized, Dynamic Centralized and Distributed role architectures of the Control Tier. These figures show that the number of messages is very similar for both Dynamic Centralized and Distributed approaches. Nonetheless, the number of messages is slightly smaller for the Fixed Centralized approach. This can be explained by the fact that in the Fixed Centralized approach, the first node that join the network plays both the Manager and the Monitor roles and when such a node fails, the system stop counting the messages that this node was monitoring.  
From Figure 9 we can conclude that the number of messages required by the framework depends on the network infrastructure, and it is positively correlated with the number of nodes of the network. Thus, AP infrastructures produce a smaller number of messages, followed by TZT and MANET networks.