# TSCH Multiflow Scheduling with QoS Guarantees:
## 2 Materials and Methods  
The Cooja simulator, available as part of the Contiki-NG operating system, was used to analyse the performance of the described schedulers using Multi-Path Ray-tracer Medium \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **SDN WISE-TSCH** & **AMUS** & **MSF** & **ORCHESTRA** \\ \hline Topology construction & SDN WISE: Beacon and Report & RPL & RPL & RPL \\ \hline Scheduling distribution & Centralised & Centralised & Distributed & Autonomous \\ \hline Resource reservation & Dynamic and specific according to deadline and data rate & Specific according data rate & One single shared cell negotiated cells & One single unicast cell \\ \hline Response to changes & \begin{tabular}{c} Yes \\ Dynamic configuration \\ and load balance \\ \end{tabular} & No. Pre-scheduling & Yes (RPL messages) & Yes (RPL messages) \\ \hline Avoid collisions & Yes & Yes & No & Yes \\ \hline Traffic classification & \
\begin{tabular}{c} Yes \\ all traffic can be marked, classified and special rules can be applied for each type. \\ \end{tabular} & No. & No &
\begin{tabular}{c} Only: \\ Broadcast (RPL message), \\ EB (Beacon), Unicast \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of features for each of the TSCH schedulers. (MRM) \(n=2.04\) and \(\sigma=6.7\). The hardware used for simulation is a intel core i7 with 16 GB of RAM and the nodes are modeled as OpenMote nodes. The payload used is 110 bytes, because the maximum packet size of the 802.15.4 standard is 127 bytes, of which 17 are used for the MAC header. A network with a mesh topology typical in the industrial sector was used, because it offers higher reliability as it can route data through multiple paths [28]. The topology is shown in Figure 3. It is composed of 1 sink node, 6 relay nodes and 3 nodes (8, 9, 10) which will introduce traffic flows to the network with different quality of service requirements. To characterise the flows, the reliability and latency requirements, typical of industrial systems, as defined in IEC 62264 (ANSI/ISA95), have been used. According to this standard, the 3 data flows used are:  
* Supervisory Control Job Based: Latency less than 100 ms, loss less than \(10^{-6}\) and number of devices less than 10. * Supervisory Control Flow Based: Latency less than 100 ms, loss less than \(10^{-7}\) and a number of devices less than 30. * Monitoring: Latency of less than 1 s, a loss of less than \(10^{-5}\) and a device count of less than 10,000. As shown in Figure 3 the flows have a different packet period: 70 ms (flow 1, type supervisory control), 140 ms (flow 2, type monitoring) and 500 ms (flow 3, type monitoring) respectively. In the simulation, two tests were carried out. Test 1 consisted of observing the behaviour of the network with low saturation, using monitoring and supervisory control flows. In this case node 9 would independently send each of the flows to the sink node. The following measurements were obtained for each of the packet periods:  
* End-to-End Delay: milliseconds that elapse from the time a packet is generated at the transmitting node and its arrival at the destination. It is measured for each packet received. * Packet Delivery Ratio (PDR): ratio of the number of packets sent and received by the destination node. * Radio Duty Cycle (RDC): percentage of time the radio remains on in the transmit or receive state. Figure 3: Topology with 10 fixed nodes. * Packet Inter-Arrival Time (PIAT): is the number of milliseconds that elapse between each reception of the same type of packet at the destination node. This metric allows evaluation of how well the network adapts to the strict time requirements. * Deadline Satisfaction Ratio (DSR): this metric is obtained from the PIAT, and is the cumulative percentage of packets that remain below the deadline. In test 2, a multi-flow test was performed to evaluate the behaviour in a network with more traffic. For this purpose, supervisory control and monitoring type flows have been used together.