Performance Evaluation of an IEEE 802.15.4-Based Thread Network for Efficient Internet of Things Communications in Smart Cities  
[PERSON]  
1 Smart Systems Engineering Laboratory, Department of Communications and Networks Engineering, Prince Sultan University, Ryadh 11586, Saudi Arabia; [EMAIL_ADDRESS] (S.B.A.K. ); [EMAIL_ADDRESS] (H.F) 1 Smart Systems Engineering Laboratory, Department of Communications and Networks Engineering, Prince Sultan University, Ryadh 11586, Saudi Arabia; [EMAIL_ADDRESS] (S.B.A.K. ); [EMAIL_ADDRESS] (H.F) 1 Smart Systems Engineering Laboratory, Department of Communications and Networks Engineering, Prince Sultan University, Ryadh 11586, Saudi Arabia; [EMAIL_ADDRESS]. The majority of IoT applications in the real world make use of single-hop wireless connectivity to the gateway based on a star topology. Alternatively, the mesh topology has also been considered that enables each node to communicate with every other node and gateway, enhancing reliability [12]. While wireless standards such as Bluetooth and ZigBee are continuously evolving to support mesh networks. To extend the support towards mesh networks, a new protocol named Thread has been developed using open and proven standards, such as IEEE 802.15.4 and 6 LoWPAN [13]. The Thread is a communication protocol that is maintained by Thread Group [14]. It has been designed to meet the requirements of applications that demand low power consumption, low data throughput, and a short communication range. Thread protocol is designed to meet the specific needs of diverse smart city applications, providing secure and scalable connectivity to a large number of devices in an energy-efficient and reliable manner. The Thread-based IoT mesh network can be connected to the global Internet using a gateway called a border router that provides connectivity through Ethernet or Wireless Local Area Network (WLAN). Thread provides end-to-end encryption, no single-point failure, and consumes low power. Thread is a relatively new protocol compared to ZigBee and Bluetooth, so its performance has not been extensively studied, especially in real-world applications with varying scenarios. To fill the aforementioned gap, this work is carried out with the objective to develop a Thread network from off-the-shelf components by analyzing the performance with varying topologies. In order to do so, a test bed was built to analyze the performance by considering one hop, two hops, and a multi-hop environment. In the literature, the performance of the Thread protocol is analyzed by using the Round Trip Time (RTT) parameter, and few have considered throughput, which is insufficient to assess its functionality. In this work, we have performed extended experiments by considering various parameters, such as RTT, packet loss ratio, and jitter. Further, the impact of varying the payload size and bit rate was also considered to analyze the performance in these varying situations. Moreover, in order to check the robustness of a network, the test bed was subjected to link failures. The experiments were performed using Raspberry Pis, manufactured by The Raspberry Pi Foundation based in Cambridge, UK, as nodes and nRF52840 dongles by Nordic Semiconductor, a company based in Oslo, Norway, as a transceiver. The contributions of this paper are the following:  
* Comprehensive performance evaluation of the Thread mesh network protocol using a test bed. While RTT and packet loss performance parameters are commonly examined in the literature on Thread, we have also specifically investigated the impact of jitter, thereby providing a more thorough analysis of the network's behavior. * A standardized IoT architecture based on Thread mesh technology provides a robust and scalable network for designing IoT solutions. * Based on the outcomes of the analysis, this paper provides recommendations for selecting the most appropriate topology for different situations. This paper proceeds as follows.