# Wireless Sensor Network Energy Model and Its Use in the Optimization of Routing Protocols
## 3 Analysis and Results under the Simulation Tool
\begin{table}
\begin{tabular}{l c} \hline \hline
**Parameter** & **Value** \\ \hline \multicolumn{2}{c}{**Physical Layer Parameters**} \\ \hline Sensitivity threshold receiver & \(-\)94 dBm \\ Transmission power & 4.5 dBm \\ \hline \multicolumn{2}{c}{**MAC Layer Parameters**} \\ \hline Maximum retransmission number & 3 \\ Maximum retry number & 5 \\ Maximum number of tries to reach & 9 \\ a node from the collector & \\ Packet error rate & 1\% \\ Average frame length & 22 bytes \\ Maximum number of backoffs & 4 \\ MAC protocol & IEEE 802.15.4 \\ MAC layer & CSMA/CA \\ \hline \multicolumn{2}{c}{**Network Layer Parameters**} \\ \hline Number of nodes & 22 \\ Maximum data rate & 250 kbps \\ Scenario & Static nodes \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation and real network parameters under CSMA/CA carrier sense multiple access with collision avoidance [34]. Figure 3: The network topology considered. to their destiny. This is why the nodes are grouped into categories called crowns, which make them take a specific level of similarity in the network. For these graph results, the network will only have a coordinating node and this will be node 1. It is important to note that crowns are formed based on the amount of links that each routing protocol forms; not all protocols have the same number of crowns to analyze. The proposed energy model lets us know exactly how much energy an average node spends on each crown. The energy model is applied to the programming and operation of the sensors to establish their energy consumption separately, depending on the type of energy. As the model is validated, it allows global and local knowledge of the energy of the nodes according to the performance parameters such as: the proximity to the coordinating node, the number of established links, the collisions that generate the amount of traffic and control packets, the delay in the delivery of information, and the processing of resources at the node level. In Figure 4, the AODV protocol presents six crowns of nodes. This may be because AODV is a reactive protocol that forms links in all directions, so the network becomes a mesh with widely redundant links. However, the fact of having so many links may produce an increase in packet collisions and protocol control packets, which generates more packet retransmissions and listening attempts to the communication channel. The advantage of presenting several crowns or levels of nodes with similar performance is the redundancy and the amount of different routes that a package can take to reach its destination. The disadvantage presented by this number of packets administered by the routing protocol is the high-energy consumption due to the possible loss of packets and their retransmission. In AODV, the crowns with the highest energy load are 1 and 2, which are the closest nodes to the coordinating node. This is understandable because they are the nodes that forward the traffic of the other nodes in the network and the coordinating node generates a bottleneck. We observe that between the last crown (crown 6) and the first two crowns, the difference in energy expenditure is 48%, which shows that nodes farther from the coordinating node have less traffic load, less collisions and less retries listening to the channel, then the CSMA algorithm runs in less times. Due to the energy model, we can also note that in crowns 1, 2, 3 and 4 the transmission and CSMA energies are similar. This may be due to the strong weight of the network that is located at the center of the topology; the AODV protocol creates a mesh and not a link tree. In Figure 5, the DSR protocol presents a structure and a quantity of crowns similar to AODV. These two protocols are the highest energy consumers of all the protocols studied in this work, with a 15% higher expenditure of energy in the nodes. Crowns 1 and 2 have the highest energy expenditure due to the redundancy of the protocol links.