Developing Management Solution for Continuous WSNs
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0 5 10 15 20 25 30 Scenarios 1 2 Flat Homogeneous AP Perimeter 3 4 Flat Homogeneous AP Center 5 6 Hierarchical Homogeneous AP Perimeter 7 8 Hierarchical Homogeneous AP Center 9 10 Hierarchical Heterogeneous AP Perimeter Delay (s) Average Delay With Management Without Management
Figure 5.10: Average delay in the proposed scenarios.
(scenarios 1 to 8) the best architecture, considering lost messages, is the one implemented in scenario 3 (homogeneous flat network with management services and access point lo- cated in the center of the monitoring area). Comparing scenarios without management, the worst cases occurs in scenarios of the homogeneous hierarchial WSNs (scenario 6 and 8). This behavior is expected because of the characteristics of this type of the network presented in Section 5.1.3.2. Other management services must be implemented for homo- geneous hierarchical to try to reduce the message loss. We can observe that management has a positive effect in all simulated scenarios, considering this metric. Since the density is controlled, the congestion and the collision are minimized. The average of lost messages could be reduced even more if specific media access control protocols for this type of WSN were already available. The management service of parameters configuration also influence the performance of management for this metric. As seen, in homogeneous network, the nodes closer to the access point tend to consume more energy, leaving the network before others. The management application configures the nodes closer to the access point to privilege the dissemination when its residual energy reaches 8% of its total capacity. Thus, nodes far from the access point can find a path to deliver their data. The hierarchical homogeneous network looses more messages because of the flow of messages when the manager indicates the leaders of the groups, the group formation and the fact that the leaders aggregate the messages of all common-nodes in the group making a larger message. Regarding lost messages, management has shown to be productive since it manages the
128 5.4. SIMULATION RESULTS
redundant nodes and privileges the communication in nodes closer to the access point.
0 10 20 30 40 50 60 70 80 90 Scenarios 1 2 Flat Homogeneous AP Perimeter 3 4 Flat Homogeneous AP Center 5 6 Hierarchical Homogeneous AP Perimeter 7 8 Hierarchical Homogeneous AP Center 9 10 Hierarchical Heterogeneous AP Perimeter Message Loss (%) Message Loss With Management Without Management
Figure 5.11: Message loss in the proposed scenarios.
5.4.3
Energy
Figure 5.12 shows the average energy consumption considering common-nodes and cluster- head energy consumption. The graph shows that the energy consumed by management services is not significant. Regarding the access point location, there is no consumption difference when management functions are implemented. The average energy consumption in scenarios of homogeneous network with and without (scenario 1 to 8) management are similar. A difference can be noticed between the comparison of homogeneous hierarchical networks (scenarios 1 to 8) and heterogeneous hierarchical networks (scenarios 9 and 10). The heterogeneous networks consume more energy since they have leaders with a higher radio range and transmit the information in a single-hop to the base station. The manage- ment improves the productivity of heterogeneous hierarchical networks (scenario 9) since it controls the common-nodes density in the groups and also configures the radio range of the leaders in relation to the distance of the base station (as observed for delay and message loss metric).
The majority of the management services executed are automatic, that is, without human interference. These results show that, besides the bidirectional flow, management can improve the productivity, decreasing the average delay in some scenarios (3, 5 and 9) and minimizing the average amount of lost messages in all scenarios (1, 3, 5, 7 and
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9) without incurring in negative influences in energy consumption. Another advantage of the management is the accompaniment of the quality of service, represented by the management of data production.
0 2 4 6 8 10 12 Scenarios 1 2 Flat Homogeneous AP Perimeter 3 4 Flat Homogeneous AP Center 5 6 Hierarchical Homogeneous AP Perimeter 7 8 Hierarchical Homogeneous AP Center 9 10 Hierarchical Heterogeneous AP Perimeter Consumed Energy (J) Energy Consumption With Management Without Management
Figure 5.12: Energy consumption in the proposed scenarios.
5.4.4
Production
Considering the service aspects of WSNs, we evaluate the production defined as the number of nodes that produce and that achieve a well succeed information dissemination. Observ- ing Table 5.3, we note that at 13 seconds of simulation, 77% of the nodes of scenario 1 deliver their information to the observer, that is, the temperature and carbon monoxide level averages that were produced by 77% of the nodes. The remaining 23% had their data lost or delayed. Between 13 and 23 seconds of the simulation, the management application generates a bidirectional flow inside the network. The effect of this traffic can be noticed at instant 23 of scenario 3 and at instant 33 of scenario 1, when the percentage of nodes that can deliver their information decreases to 63% and 74%, respectively. Following, at 53 seconds of simulation, the nodes start to leave the network due to energy problems. The network of the scenario 1 (with the access point in the perimeter) stops its activities at 63 seconds of simulation. The network of the scenario 3 stops its activities at 83 seconds of simulation. Therefore, the access point has a better location in the center when talking about flat networks.
130 5.4. SIMULATION RESULTS
Table 5.3: Number of nodes producing in the homogeneous flat WSN. Scenario 13s 23s 33s 43s 53s 63s 73s 83s
1 77% 80% 74% 88% 71% 0 0 0
3 78% 63% 69% 71% 71% 68% 17% 0
without management, the observer can not know how, when and were the data is produced. Observing Table 5.4, we note that the heterogeneous hierarchical network (scenario 9) has a greater production time. On the other hand, the homogeneous hierarchical networks (scenarios 5 and 7) stop producing even before the flat networks. At 52 seconds of sim- ulation, the homogeneous hierarchical network with access point located in the middle of the network is out of service. At 77 seconds of simulation, the hierarchical homogeneous network with access point in the perimeter stops its activities. At 102 seconds of simu- lation, the heterogeneous hierarchical network is still producing, with 85% of the nodes taking part in the temperature and carbon monoxide level averages construction. Because the network productivity analysis is a service offered by the management, this information is not available to scenarios 2, 4, 6, 8 and 10.
Table 5.4: Number of nodes producing in the hierarchical homogeneous and heterogeneous WSN.
Scenario 27s 52s 77s 102s
5 18% 25% 0 0
7 7% 0 0 0
9 53% 93% 97% 85%
Regarding energy consumption, this metric is similar for all scenarios of homogeneous WSNs. However, the lifetime is different.
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