Scalability Enhancement on Software Defined Industrial Wireless Sensor Networks Over TSCH

Industry 4.0 digitization requirements have led to widespread adoption of industrial wireless sensor networks (IWSNs) in manufacturing environments. These require strict control of the traffic flowing over the network to ensure the quality of service. Software-defined networks (SDNs) can address this challenge, as their centralized operation allows routing and media access control (MAC) protocols to be optimized. In addition, in many cases a massive deployment of metering devices is necessary, therefore the network must be scalable, to allow an increase in the number and density of nodes in the network. This implies an increase in the control traffic required by SDNs, generating a significant reduction in the throughput available for data. This is because the length of the timeslot limits the throughput of the network in protocols that uses time division, such as the Time Slotted Channel Hopping (TSCH), conditioning the number of nodes that the network can have and its data sending rate. In this paper, we propose to exploit the integration and reconfiguration capabilities of SDN to extend the number of nodes in the network through the use of multi-radio sinks called virtual sinks, orchestrated from the SDN controller, and extending their use to multiple SD-IWSNs to take full advantage of the radio spectrum. To optimize bandwidth usage, the SDN controller will allocate network slices, allowing nodes to send data with a high frequency using dedicated channels. The results obtained show that the use of multi-radio sinks provides for increasing the maximum number of nodes that can be deployed while preserving the quality of service (QoS) requirements. A linear increase in nodes at least 0.7 times for each radio interface is obtained compared to an SD-IWSN with a traditional sink. In addition, the use of virtual sinks increases the packet frequency of the network by a factor equal to the number of radio interfaces. Moreover, the total number of nodes is improved through the coexistence of multiple SD-IWSNs, where up to 13.7 times more nodes can be scheduled using all the available spectrum orchestrated from the same SDN controller.