# CONE: A Connected Dominating Set-Based Flooding Protocol for Wireless Sensor Networks
## 3 Design and Implementation of CONE
### Flooding Protocol
During these ten minutes, node 1 (see Figure 16)--as an initiator--broadcasts a packet every 15 seconds in order to flood the messages through the whole network. During the first 90 seconds, CONE uses the broadcasts to construct a CDS. After the first 90 seconds, CONE halts the CDS construction and starts the data dissemination by flooding. After ten minutes, we measure the average current consumption of all nodes. #### 4.2.2 Results

As Figure 16 shows, in our experiment in FlockLab, CONE constructs a CDS with the green node 13, 15, 25, and 28 as dominators. Therefore, these nodes are many enough to cover the whole network, thus, continue to forward packets during the flooding process. Based on the connections between nodes, we can also see that a packet can flow from initiator 1 through dominators 15, 28, and 13 to dominator 25. Furthermore, every non-dominator is in transmission range of at least one dominator. This means that if a packet is forwarded by the dominators, then every other node in the network can receive that packet without retransmitting it. Thus, while in a flooding process, the dominators (in

Figure 16: Constructed CDSs in the FlockLab experiments. The dominators are colored in green. The initiator is colored in grey. The edges indicate the active links between nodes. We only show active links between dominators and their neighboring nodes due to the large number of active links. Figure 15: Deployment of sensor nodes in FlockLab. a CDS) receive packets from the initiator and forward the packets to all other nodes in the network. The non-dominators save a lot of energy during the flooding process by having their radio turned off for a longer time. Besides, this is sufficient to ensure that every node in the network is able to receive the packets from the initiator. Figure 17 shows the energy consumption of the network in our FlockLab experiment after ten minutes. In CONE, the energy consumption of node 28, 25, and 15 is higher compared to the Trickle protocol. This could be expected due to the fact that these nodes are dominators and, therefore, have to forward packets so that the rest of the network can receive these packets. However, in CONE the energy consumption of all non-dominators is lower compared to Trickle. This results in an overall 15% lower average energy consumption for the network in CONE compared to Trickle. Because the radio transceiver of nodes consumes a significant amount of power when turned on, the non-dominators save energy by not retransmitting packets. With these results, we conclude that CONE decreases the average energy consumption in a network. However, the forwarding of packets during the flooding process is not distributed among all nodes in the network, but only among dominators. This means that dominators in CONE may have to forward packets more often compared to individual nodes in Trickle. Thus, CONE does not necessarily decrease the energy consumption of individual dominators. ## 5 Conclusions

The goal of this work was to improve the energy efficiency of WSN network flooding by exploiting a CDS on top of the flooding protocol. In this article, we presented the design and implementation of our CDS-based flooding protocol CONE. CONE constructs a CDS with only slight information of a network's topology. Besides, we compared CONE with the baseline protocol Trickle, both in simulations and in a real-world testbed, in term of RDC, packet loss, and energy consumption. The results showed that CONE successfully decreases the number of lost packages for all nodes in the simulations. Testbed results demonstrated that CONE decreases the average energy consumption of a network during network flooding. However, CONE does not necessarily decrease energy consumption of dominator nodes. As future work, we would like to improve CONE so that it can be used to construct a CDS while causing less overhead and at the same time resulting in a smaller-sized CDS.