Experimental Evaluation of a LoRa Wildlife Monitoring Network in a Forest Vegetation Area

Smart agriculture and wildlife monitoring are one of the recent trends of Internet of Things (IoT) applications, which are evolving in providing sustainable solutions from producers. This article details the design, development and assessment of a wildlife monitoring application for IoT animal repelling devices that is able to cover large areas, thanks to the low power wide area networks (LPWAN), which bridge the gap between cellular technologies and short range wireless technologies. LoRa, the global de-facto LPWAN, continues to attract attention given its open specification and ready availability of off-the-shelf hardware, with claims of several kilometers of range in harsh challenging environments. At first, this article presents a survey of the LPWAN for smart agriculture applications. We proceed to evaluate the performance of LoRa transmission technology operating in the 433 MHz and 868 MHz bands, aimed at wildlife monitoring in a forest vegetation area. To characterize the communication link, we mainly use the signal-to-noise ratio (SNR), received signal strength indicator (RSSI) and packet delivery ratio (PDR). Findings from this study show that achievable performance can greatly vary between the 433 MHz and 868 MHz bands, and prompt caution is required when taking numbers at face value, as this can have implications for IoT applications. In addition, our results show that the link reaches up to 860 m in the highly dense forest vegetation environment, while in the not so dense forest vegetation environment, it reaches up to 2050 m

Scheduling Models for Industrial Internet of Things Networks

IEEE 802.15.4-2015 Time Slotted Channel Hopping (TSCH) Networks have gained a lot of attention within the Industrial Internet of Things (IIoT) research community due to its effectiveness in improving reliability and providing ultra-low power consumption for industrial applications, where communication is orchestrated by a schedule. The key feature of TSCH is the scheduling of time slots and frequencies, which can be typically created in various ways but should be computed according to specific requirements, such as throughput, energy, reliability and latency. Despite the promising features of the TSCH, IEEE 802.15.4 standard leaves out of its scope in defining how the schedule is built and maintained, which is the focus of this research. This thesis presents a centralized scheduling model in IEEE 802.15.4-2015 TSCH Networks, where the gateway makes frequency allocations and time slot assignments. We propose different scheduling models focusing on maximizing the overall throughput, minimizing the average scheduling delay, maximizing the energy efficiency, and providing throughput fairness through max-min fair approach. In achieving these, we devise algorithm-based optimal, sub-optimal yet heuristic algorithms. In addition to the heuristic algorithms and simulation-based studies, this thesis also provides a graph theoretical approach and proposes polynomial time graph algorithms. Moreover, experimental measurements are conducted on different platforms and various operating systems to assess the energy consumption and evaluate the impact of TSCH protocol. Lastly, the thesis focuses on emerging technologies for the Internet of Things (IoT), where we present a simple and general Software Defined Networking (SDN)-IoT architecture with Network Function Virtualization (NFV) implementation, providing specific choices on where and how to adopt SDN and NFV approaches to address the new challenges of the IoT

An efficient centralized scheduling algorithm in IEEE 802.15.4e TSCH networks

IEEE 802.15.4e Time Slotted Channel Hopping (TSCH) standard has gained a lot of attention within the Industrial Internet of Things research community due to its effectiveness in improving reliability and providing ultra-low power consumption for industrial applications, and in which its communication is orchestrated by a schedule. Despite its relevance, the standard leaves out of its scope in defining how the schedule is built, updated and maintained. This open issue is one of the trending topics in the IETF 6TiSCH WG, that still need to be addressed. This work focuses on scheduling in TSCH networks in a centralized manner where the gateway makes time and frequency slot allocation. This paper formulates the scheduling problem as a throughput maximization problem and delay minimization problem. We propose a graph theoretical approach to solve the throughput maximization problem in a centralized way. The combinatorial properties of the scheduling problem are addressed by providing an equivalent maximum weighted bipartite matching (MWBM) problem to reduce the computational complexity and also adopting the Hungarian algorithm in polynomial time. Simulation results are provided to evaluate the performance of the proposed scheme

Performance evaluation of energy saving MAC protocols in WSN operating systems

Sensing, computing and communication are the main features of a wireless sensor network (WSN) which serves a wide range of applications. Despite its versatility and simplicity, it brought up various challenges such as limited storage, power consumption from radio activities, just to mention a few. The distinguishing traits of sensor networks have a direct impact on their protocol design at each layer, especially at the Medium Access Control (MAC) layer since it manages transmission scheduling as well as duty cycling for energy conservation. To maximize energy efficiency of WSNs, a critical analysis of the radio duty cycle of the WSN operating systems were carried out with experimental evaluation. Moreover, we focus on the energy consumption by conducting experimental measurements on different platforms i.e. OpenMote-CC2538 on various operating systems. Results shows that IEEE 802.15.4e Time Synchronized Channel Hopping (TSCH) has great impact on the energy consumption with respect to other radio duty cycles

Throughput Maximizing and Fair Scheduling Algorithms in Industrial Internet of Things Networks

Time-Slotted Channel Hopping (TSCH) mode in the IEEE 802.15.4-2015 standard provides ultra-high reliability and ultra-low power consumption to sensor devices. The key feature of TSCH is the scheduling of time slots and frequencies, which falls outside the current standards. In this paper, we focus on throughput maximizing and max-min fair scheduling problems in a centralized TSCH networks. At first, a polynomial time algorithm for the throughput maximizing scheduling problem is proposed. We proceed to investigate and deliberate on some instances of the problem with their combinatorial properties. Secondly, a novel auction based scheduling algorithm that uses a first-price sealed-bid auction mechanism is presented for the throughput maximizing problem. Simulation results show that the proposed algorithm obtains a close throughput performance to the optimal one obtained through CPLEX with a much lower complexity. Moreover, we propose a novel heuristic for the max-min fair scheduling problem and demonstrate its performance through extensive simulations in terms of the total throughput and fairness varying the number of nodes, frequencies and antennas. Simulation results indicate the effectiveness of the proposed algorithm and its close performance to the optimal solution

An energy efficient centralized scheduling scheme in TSCH networks

IEEE 802.15.4-2015 is the third revision of IEEE 802.15.4 Standard for Low-Rate Wireless Networks. The standard presents Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol, which provides high reliability and low power consumption to various industrial applications. Despite the effectiveness and the importance of the TSCH protocol, the standard leaves out of its scope in defining how the schedule is built and maintained. In this work, we focus on scheduling in IEEE 802.15.4-2015 TSCH networks from the energy efficiency perspective in a centralized manner where the gateway makes frequency allocations and time slot assignments. At first, we derive an energy consumption model of a TSCH node to determine the network lifetime. Afterwards, we formulate the scheduling problem as an energy efficiency maximization problem, which is a nonlinear integer programming. Motivated by the high computational complexity of the problem, we propose a low-complexity Energy Efficient Scheduler (EES) and Vogel's Approximation Method Heuristic Scheduling Algorithm (VAM-HSA). We make a comparison with the Round Robin Scheduler (RRS) and analyse the schedulers in terms of success probability and energy efficiency. Performance evaluation indicates that EES and VAM-HSA perform better in terms of energy efficiency, while at the same time yielding a good throughput