Systematic literature survey: applications of LoRa communication

LoRa is a communication scheme that is part of the low power wide are network (LPWAN) technology using ISM bands. It has seen extensive documentation and use in research and industry due to its long coverage ranges of up-to 20Km or more with less than 14dB transmit power. Moreover, some applications report theoretical battery lives of upto 10years for field deployed modules utilising the scheme in WSN applications. Additionally, the scheme is very resilient to losses from noise, as well bursts of interference through its FEC. Our objective is to systematically review the empirical evidence of the use-cases of LoRa in rural landscapes, metrics and the relevant validation schemes. In addition the research is evaluated based on (i) mathematical function of the scheme (bandwidth use, spreading factor, symbol rate, chip rate and nominal bit rate) (ii) use-cases (iii) test-beds, metrics of evaluation and (iv) validation methods. A systematic literature review of published, refereed primary studies on LoRa applications was conducted. Using articles from 2010-2019. We identified 21 relevant primary studies. These reported a range of different assessments of LoRa. 10 out of 21 reported on novel use cases. As an actionable conclusion, the authors conclude that more work is needed in terms of field testing, as no articles could be found on performance/deployment in Botswana or South Africa despite the existence of LoRa networks in both countries. Thus researchers in the region can research propagation models performance, energy efficiency of the scheme and MAC layer as well as the channel access challenges for the region

Towards the efficient use of LoRa for wireless sensor networks

Since their inception in 1998 with the Smart Dust Project from University of Berkeley, Wireless Sensor Networks (WSNs) had a tremendous impact on both science and society, influencing many (new) research fields, like Cyber-physical System (CPS), Machine to Machine (M2M), and Internet of Things (IoT). In over two decades, WSN researchers have delivered a wide-range of hardware, communication protocols, operating systems, and applications, to deal with the now classic problems of resourceconstrained devices, limited energy sources, and harsh communication environments. However, WSN research happened mostly on the same kind of hardware. With wireless communication and embedded hardware evolving, there are new opportunities to resolve the long standing issues of scaling, deploying, and maintaining a WSN. To this end, we explore in this work the most recent advances in low-power, longrange wireless communication, and the new challenges these new wireless communication techniques introduce. Specifically, we focus on the most promising such technology: LoRa. LoRa is a novel low-power, long-range communication technology, which promises a single-hop network with millions of sensor nodes. Using practical experiments, we evaluate the unique properties of LoRa, like orthogonal spreading factors, nondestructive concurrent transmissions, and carrier activity detection. Utilising these unique properties, we build a novel TDMA-style multi-hop Medium Access Control (MAC) protocol called LoRaBlink. Based on empirical results, we develop a communication model and simulator called LoRaSim to explore the scalability of a LoRa network. We conclude that, in its current deployment, LoRa cannot support the scale it is envisioned to operate at. One way to improve this scalability issue is Adaptive Data Rate (ADR). We develop two ADR protocols, Probing and Optimistic Probing, and compare them with the de facto standard ADR protocol used in the crowdsourced TTN LoRaWAN network. We demonstrate that our algorithms are much more responsive, energy efficient, and able to reach a more efficient configuration quicker, though reaching a suboptimal configuration for poor links, which is offset by the savings caused by the convergence speed. Overall, this work provides theoretical and empirical proofs that LoRa can tackle some of the long standing problems within WSN. We envision that future work, in particular on ADR and MAC protocols for LoRa and other low-power, long-range communication technologies, will help push these new communication technologies to main-stream status in WSNs

Identifying Malicious Nodes in Multihop IoT Networks using Dual Link Technologies and Unsupervised Learning

Packet manipulation attack is one of the challenging threats in cyber-physical systems (CPSs) and Internet of Things (IoT), where information packets are corrupted during transmission by compromised devices. These attacks consume network resources, result in delays in decision making, and could potentially lead to triggering wrong actions that disrupt an overall system's operation. Such malicious attacks as well as unintentional faults are difficult to locate/identify in a large-scale mesh-like multihop network, which is the typical topology suggested by most IoT standards. In this paper, first, we propose a novel network architecture that utilizes powerful nodes that can support two distinct communication link technologies for identification of malicious networked devices (with typical singlelink technology). Such powerful nodes equipped with dual-link technologies can reveal hidden information within meshed connections that is hard to otherwise detect. By applying machine intelligence at the dual-link nodes, malicious networked devices in an IoT network can be accurately identified. Second, we propose two techniques based on unsupervised machine learning, namely hard detection and soft detection, that enable dual-link nodes to identify malicious networked devices. Our techniques exploit network diversity as well as the statistical information computed by dual-link nodes to identify the trustworthiness of resource-constrained devices. Simulation results show that the detection accuracy of our algorithms is superior to the conventional watchdog scheme, where nodes passively listen to neighboring transmissions to detect corrupted packets. The results also show that as the density of the dual-link nodes increases, the detection accuracy improves and the false alarm rate decreases

Acesso ao meio em redes LoRa com múltiplas gateways de baixo custo

With the emergence of Low Power Wide Area Network (LPWAN) technologies, as support to Internet of Things (IoT) applications, Long-Range (LoRa) popularity emerged, being actually one of the most up-and-coming LPWAN technologies, despite the low-rate transmissions and duty-cycle restrictions. Such recognition is due to LoRa's suitable characteristics for large-scale IoT networks, which span from long-range communications, guaranteed by its proprietary modulation scheme, to low power consumption, a fundamental feature for IoT sensor networks. The focus of this dissertation is the study of medium access control strategies in large-scale single-channel LoRa networks with multiple gateways with respect to the amount of delivered useful information and network access fairness. Firstly, it is proposed and analysed a medium access control strategy for LoRa networks with multiple single-channel gateways and the same transmission parameters are used by the entire network. It is based on the pure- ALOHA protocol used in LoRa, and each end-device uses control packets to advertise its transmissions. In the following, a new access strategy based on channel hopping is proposed. In this, each ED uses the transmission characteristics that are most convenient to it, with respect to the signal's quality with the single-channel GWs that are in its communication range. These strategies aimed to increase the efficiency of the network, allowing end-devices to transmit faster and increasing the percentage of successfully transmitted packets by reducing the amount of collisions, given the regulation of the competition in the access to the transmission medium.Com o aparecimento das tecnologias Low Power Wide Area Network (LPWAN), como suporte para as aplicações da Internet of Things (IoT), Long- Range (LoRa) tornou-se popular, sendo atualmente uma das tecnologias LPWAN mais promissoras, ainda que as suas transmissões tenham baixas taxas de débito e restrições nos ciclos de trabalho. A popularidade deve-se às características que a tecnologia LoRa possui adequadas para redes IoT de larga escala, que vão desde transmissões de longo alcance, garantidas pelo esquema de modulação que esta utiliza, até ao baixo consumo de energia, aspeto crucial em redes de sensores da IoT. O foco desta dissertação é o estudo de estratégias de controlo de acesso ao meio para redes LoRa de grande escala com canal único e múltiplas gateways, relativamente à quantidade de informação útil entregue e à justiça no acesso ao meio. Inicialmente, é proposto e analisado um esquema de controlo de acesso ao meio para redes LoRa com múltiplas gateways e com um único canal, onde os mesmos parâmetros de transmissão são utilizados por toda a rede. Este é baseado no protocolo ALOHA puro utilizado no LoRa, e cada nó terminal utiliza pacotes de controlo para anunciar as suas transmissões. No seguimento, é proposto uma nova estratégia de acesso ao meio baseado na alteração do canal de transmissão. Neste, cada nó terminal usa as características de transmissão que lhe forem mais favoráveis, relativamente à qualidade de sinal que tem com as gateways que se encontram no seu alcance de comunicação. Estas estratégias visaram aumentar a eficiência da rede, permitindo que os nós terminais transmitam mais rapidamente, e aumentando a percentagem de pacotes transmitidos com sucesso através da redução da quantidade de colisões, possibilitada pela regulação da competição no acesso ao canal de transmissão.Mestrado em Engenharia Eletrónica e Telecomunicaçõe