# Time Slotted Channel Hopping and ContikiMAC for IPv6 Multicast-Enabled Wireless Sensor Networks
## 6 Results
### Energy Consumption per Hop  
The last parameter used to compare LL unicast with LL broadcast forwarding, and the two protocols between them was the energy consumption per hop. The results for this performance parameter are shown in Figure 15 for topologies without interference, Figure 16 for topologies with interference between same rank nodes, and Figure 17 for topologies with the random placement of the nodes. Figure 11: Delay comparison between LL unicast and LL broadcast and between ContikiMAC and TSCH on topologies without interference between same rank nodes. (**a**) Results for LL unicast in BMRF over TSCH. (**b**) Results for LL broadcast in BMRF over TSCH. (**c**) Results for LL unicast in BMRF over ContikiMAC. (**d**) Results for LL broadcast in BMRF over ContikiMAC. Figure 12: Delay comparison between LL unicast and LL broadcast and between ContikiMAC and TSCH on topologies with interference between same rank nodes. (**a**) Results for LL unicast in BMRF over TSCH. (**b**) Results for LL broadcast in BMRF over TSCH. (**c**) Results for LL unicast in BMRF over ContikiMAC. (**d**) Results for LL broadcast in BMRF over ContikiMAC. Figure 13: Delay comparison between LL unicast and LL broadcast and between ContikiMAC and TSCH on topologies with a random placement of nodes. (**a**) Results for LL unicast in BMRF over TSCH. (**b**) Results for LL broadcast in BMRF over TSCH. (**c**) Results for LL unicast in BMRF over ContikiMAC. (**d**) Results for LL broadcast in BMRF over ContikiMAC. Figure 14: Retransmission influence on LL unicast (**a**) PDR results for LL unicast in BMRF over TSCH without retransmissions. (**b**) Delay results for LL unicast in BMRF over TSCH without retransmissions. (**c**) Delay results for LL unicast in BMRF over TSCH without retransmissions. Figure 15: Energy comparison between LL unicast and LL broadcast and between ContikiMAC and TSCH on topologies without interference between same rank nodes. (**a**) Results for LL unicast in BMRF over TSCH. (**b**) Results for LL broadcast in BMRF over TSCH. (**c**) Results for LL unicast in BMRF over ContikiMAC. (**d**) Results for LL broadcast in BMRF over ContikiMAC. The normal operation of TSCH (TSCH synchronization messages and messages for operating the schedule) used most of the energy (compared to the sending/receiving of packets), resulting in an overall higher energy consumption. In contrast, for ContikiMAC, sending/receiving was inefficient when collisions appeared. This behaviour could also be seen in the theoretical model (Tables 2 and A1). Another trend that could be observed in the case of ContikiMAC in Figure 15c,d, Figure 16c,d, and Figure 17c,d was the drop in energy consumption at the last hop since this hop did not need to transmit and retransmit any packets. Taking the highlighted advantages into consideration, TSCH is the preferred protocol when there is a lot of traffic in the network and ContikiMAC is more suitable in situations where packets are sent rarely. For the topologies with no interference or with interference only between same rank nodes, the energy consumption of BMRF on top of TSCH and in the broadcast mode was higher than the energy consumption for LL unicast forwarding Figure 15a,b and Figure 16a,b. The addition of an entire slotframe dedicated to data multicast traffic was the cause of these results. The energy consumption also varied with the number of children a node had, since the type of slot we chose for the slotframe dedicated to the broadcast data traffic was receiver-based. For this type of slot, as many listening slots as the number of neighbors that want to receive packets were allocated.