## 5 Integration of EOLSR and SERENA  
### Benefits Resulting from the Integration  
Integrating EOLSR with SERENA requires the choice of a coloring supporting broadcast. Indeed, \(Hello\) and \(TC\) messages of EOLSR are broadcast. Thus, for general communications with immediate acknowledgement, three-hop coloring is needed. For tree communication with immediate acknowledgement, \"SERENA with ack and broadcast\" is required. These \(Hello\) and \(TC\) messages must be taken into account in the dimensioning of the color slot duration. We now evaluate the benefits brought by the integration of EOLSR and SERENA (three-hop coloring). We first quantify the increase of network lifetime brought by EOLSR, SERENA+OLSR and SERENA+EOLSR respectively in different network configurations. Network density is set to 10, the number of nodes ranges from 50 to 200. In these simulations, the \(Hello\) and \(TC\) messages have not been considered in order to get simulation results more quickly. We observe in Figure 17 that compared to OLSR, EOLSR improves network lifetime, the improvement is more noticeable when the number of nodes is higher than 100. This can be explained by a higher number of possible routes. SERENA  
Figure 16: Example of tree coloring: (a) TDMA-ASAP coloring; (b) SERENA with immediate acknowledgement coloring. provides the most important contribution in network lifetime increase. For instance, with 100 nodes, the network lifetime is multiplied by 6 compared to OLSR. Furthermore, the integration of EOLSR and SERENA leads to the highest network lifetime. We point out that this lifetime increase is higher than the sum of the increases obtained by EOLSR and SERENA taken separately. As a new result, we evaluate the amount of data delivered to the user. We observe that this lifetime increase is accompanied by an increase in the amount of user data delivered as shown in Figure 17(b). This improvement represents a real benefit of the SERENA+EOLSR integration as it is directly observable by the end user. We now quantify the distribution of energy consumed in the different radio states for OLSR, EOLSR, SERENA+OLSR and SERENA+EOLSR. Results are illustrated in Figure 18 for a network of 100 nodes and a density of 10. These results extend those published in [7] by considering three-hop coloring instead of two-hop coloring. Figure18 determines the energy consumed by each protocol in each radio state: the left part of the figure highlights the protocol whereas the right part highlights the state. Unsurprisingly, OLSR has a poor energy efficiency: the main part of energy is consumed in the idle and interference states. The useful states, transmit and receive, represent the smallest part of consumed energy. EOLSR decreases the energy part consumed in the idle state. This is because the EMPRs selection takes into account the residual energy of nodes and avoids nodes with a low residual energy. In other words, EOLSR tends to balance the residual energy of nodes by changing the EMPRs selection when the energy of these nodes significantly decreases, unlike OLSR where the same intermediate nodes are in charge of transmitting. Hence, with EOLSR the number of nodes that have transmitted during network lifetime is higher. This, combined with a longer network lifetime, increases the energy lost in interferences. Another striking result is that no energy is lost in interferences with SERENA, leaving more energy to send and receive user messages. This can be explained by the three-hop vertex coloring: the nodes two-hop away from a transmitter are sleeping. As expected, SERENA considerably reduces the energy wasted in the idle  
Figure 17: Comparative performances of OLSR, EOLSR, SERENA+OLSR, SERENA+EOLSR. (a) Network lifetime; (b) Amount of user data delivered. state. The integration of SERENA and EOLSR leads to a better energy efficiency: more energy is used to transmit and receive user messages. This performance evaluation shows that SERENA+EOLSR together contribute to a more efficient use of network resources. Node coloring avoids collisions.