# An OCARI-Based Wireless Sensor Network for Heat Measurements during Outdoor Fire Experiments
## Appendix A MACARI and OSERENA--Two Innovative Elements in the OCARI Stack  
The MaCARI corresponds to the implementation of a medium access protocol relying on the IEEE 802.15.4 physical layer, deterministic, and low power consumption. The protocol is more principally enhanced on the MAC layer and implements standby and improved traffic routing algorithms by considering residual energy in each node. Its strength also offers an efficient activity periods sequencing algorithm for each node of the network. In more common terms, the MaCARI algorithm proceeds by cutting out the node activity in global cycles, which periodically recur. The CPAN is in charge of network nodes synchronisation. Thus, it recurrently broadcasts a beacon frame that is used to indicate activity cycles to all other nodes (cf. Figure 11). A synchronisation order is written into the frame in the destination to network PANs to avoid beacon frame collisions during synchronisation periods. Figure 11 illustrates the node synchronisation process in a tree topology. In an OCARI network, during synchronisation phases, the coordinator copies beacon frame content and resends it without modification. Subsequently, it is sufficient that a node receives a beacon frame, and it synchronises irrespective of the emitter. Specifically, this ensures good device resilience. Network resilience is defined as the ability of a network to provide and maintain an acceptable level of service when various faults and challenges occur during its normal operation [29]. The reader requires more substantial information on the MaCARI protocol, and thus benefits by reading [19]. The resulting enhanced quality of service from OCARI with respect to Zigbee and due to the MACARI implementation is the first feature of the new WSN.  
Given the aim of developing a wireless measurement system, it is necessary to ensure that the deviation of the local clocks of the nodes during the synchronisation process does not consequently delay time slicing and does not affect the measurement quality within the allocated time and specifically during fire experiments at the field scale. Given the OSERENA scheduling algorithm, the collecting experimental data system is equipped to resist disruption that may be created by large flames. The OSERENA algorithm relies on the theoretical principles of graph colouring algorithms that are commonly used to enhance the effectiveness of MAC layer protocols. Generally, the algorithms consist of assigning a colour to graph vertices of a routing tree wherein the root is a data well [30; 31; 32; 33]. The allocation of colours is performed such that two adjacent nodes do not exhibit the same colour, and thus does not emit in the same time slot. In the OSERENA algorithm, nodes coloration permits alternation over node activity and standby periods in which the radio module is switched off to save battery energy. A maximum 3-hop colouring is implemented for the node to schedule transmissions on the medium. Subsequently, during the neighbourhood detection phase, each node determines its neighbour nodes by periodically emitting \"Hello\" messages to its adjacent nodes at the 1-hop. Readers interested in more details on OSERENA can consult References [34; 35; 36] (Table A1). The second OCARI feature guarantees a low consumption rate. Specifically, the OSERENA introduces switch-off periods, thereby preserving battery power supplies.