A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Low-power wide area networking technology offers long-range communication, which enables new types of services. Several solutions exist; LoRaWAN is arguably the most adopted. It promises ubiquitous connectivity in outdoor IoT applications, while keeping network structures and management simple. This technology has received a lot of attention in recent months from network operators and solution providers. However, the technology has limitations that need to be clearly understood to avoid inflated expectations and disillusionment. This article provides an impartial and fair overview of the capabilities and limitations of LoRaWAN. We discuss those in the context of use cases, and list open research and development questions. <s> BIB001 </s> A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Due to distributed nature, dynamic topology and resources constraints of tiny sensing nodes in wireless sensor networks (WSNs), the quality of service (QoS) support is a challenging issue. However, satisfying the stringent QoS requirements is an open problem. QoS aware protocols for WSNs have gained recently considerable attention of the researchers. In this paper, we focus on the QoS satisfaction in WSNs, basics of QoS support in WSNs, and more importantly challenge, requirements of QoS at each layer. Furthermore, we review the QoS protocols and categorize the QoS aware protocols and elaborate their pros and cons. We also discuss the QoS parameters with respect to each protocol performance parameters. A survey and comprehensive discussion on the QoS aware protocols of WSNs are presented, including their strengths and limitations. Finally, we also survey some computational intelligence (CI) techniques and find the basic requirements of such techniques. Moreover, we study these CI techniques in the light of QoS management and tabulate the level of each CI technique for QoS management. The paper is concluded with open research issues. <s> BIB002 </s> A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Nowadays the Internet of Things (IoT) is one of the most promising application areas in information technology for future products and services. Therefore, it is not surprising that new technologies arise, which are marketed as “the most useful technology” for applications in IoT devices. In this study, we focus on the new communication technology called LoRaWAN. Our aim is to evaluate the usefulness of LoRaWAN technology in the field of IoT, and especially in sensor network solutions. The research methodology is a literature survey and primary articles were selected by means of a systematic literature review. More than fifty suitable research papers were identified. From these, the following research questions were formulated: “How to categorize LoRa research papers?” and “What are the application trends in LoRa?” This study presents a way to categorize research papers with diverse themes. In addition, this survey reveals the most recent trends in research and practical applications of LoRa. Finally, this study will give recommendations for researchers and practitioners on how the advantages of LoRa-based technologies could be fully exploited in the development of IoT systems and solutions. <s> BIB003 </s> A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Internet of Things (IoT) expansion led the market to find alternative communication technologies since existing protocols are insufficient in terms of coverage, energy consumption to fit IoT needs. Low Power Wide Area Networks (LPWAN) emerged as an alternative cost-effective communication technology for the IoT market. LoRaWAN is an open LPWAN standard developed by LoRa Alliance and has key features i.e., low energy consumption, long-range communication, builtin security, GPS-free positioning. In this paper, we will introduce LoRaWAN technology, the state of art studies in the literature and provide open opportunities. <s> BIB004 </s> A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Low-power wide-area network (LPWAN) protocols, such as a long range wide area network (LoRaWAN), are key to ensuring scalable wireless communication for Internet of Things devices. In this paper, an analysis of this protocol through a performance evaluation of a permanent outdoor LoRaWAN tested is presented. To ensure accurate results, tests lasted at least 17 h and required 1000 packets per node. The evaluation focused on the impact that the adaptive data rate (ADR) scheme, payload length, link checks, and acknowledgements had on the packet delivery ratio (PDR) of the testbed. The collected data showed that enabling the ADR scheme reduced the PDR. The ADR scheme had six data rates, which consist of a spreading factor and bandwidth combination, to choose from. Analysis revealed that the scheme primarily assigning either the fastest data rate (SF7BW250) or the slowest (SF12BW125) to nodes, regardless of distance. Furthermore, the scheme's assignments show the signs of oscillation, with nodes being instructed to abruptly change between SFs. The impact of payload length and link checks on the PDR was not pronounced, but enabling acknowledgements did show significant improvements. <s> BIB005 </s> A Survey on the Viability of Confirmed Traffic in a LoRaWAN <s> I. INTRODUCTION <s> Nowadays the IoT paradigm is attracting interest in the scientific and commercial fields. ::: This thesis focuses on the solution combining LoRa and LoRaWAN and on its performance when reliable communication is employed. ::: The discussion presents the implementation of LoRaWAN reliable communication in the ns-3 simulator and proposes a mathematical model for performance evaluation. The performance of the system and the validity of the proposed model are evaluated by means of simulations. <s> BIB006
The Internet of Things (IoT) industry is growing rapidly with more and more devices being deployed. These devices are frequently battery-powered and are scattered over large areas, thus requiring communication technologies designed to meet their needs  . This need has been met through the development of Low Power Wide Area Network (LPWAN) technologies such as Sigfox, NB-IoT and the focus of this paper: LoRa Wireless Area Network (LoRaWAN). Since the release of the LoRaWAN protocol in 2015, the conducted research has focused on a few areas such as exploring the Physical layer (PHY), performance evaluations examining range and throughput, and the protocol's Adaptive Data Rate (ADR) scheme. Surveys on the LoRaWAN protocol, such as  - BIB003 all examined the published LoRaWAN literature and attempted to classify the work into sections. The associate editor coordinating the review of this manuscript and approving it for publication was Tawfik Al-Hadhrami . These works currently cover multiple topics such as security, communication range, energy consumption, link coordination and suitable LoRaWAN applications. These surveys are very valuable, but as they are not focused on a specific topic, do not explore an aspect such as ACKs extensively. The negative impact of ACKs on network performance is noted in  , and the authors suggest the creation of a dynamic retransmission policy. They further note that the factors triggering retransmission must be extensively studied before a dynamic policy is created. The review presented in  , examines several works studying performance at the physical and network levels. The review examines several topics such as interference (from other technologies and self-interference), power consumption, security and the ADR scheme but only briefly discusses acknowledgements. When the literature was surveyed in BIB004 , it was found that most works focused on coverage tests and the various applications LoRaWAN could be suited for. The coverage of acknowledgements, however, are limited to their description as part of the section detailing the LoRaWAN protocol's inner workings. A total of 54 papers were classified into 5 categories in BIB003 . It was noted that the current trend is performance evaluations through experimental work and a need for simulation and modelling work was identified. The role of acknowledgements was not an aspect investigated in this paper. The protocol could be the technology needed for IoT deployments to reach proper scale, but several IoT use cases are only viable if their required Quality of Service (QoS) levels can be met  . LPWAN technologies are frequently marketed as being able to support very large networks, but these claims have some conditions which are only revealed once you examine the QoS levels achievable in a large network BIB001 . The QoS needs in a Wireless Sensor Network (WSN) tends to differ from those in wired networks as the limited device resources, the large number of nodes, different traffic types and unreliability of radio transmissions must be dealt with BIB002 . IoT applications are also unique and depending on the IoT use case, different QoS parameters such as latency, data rate or reliability are key  . This work focuses on one aspect of the LoRaWAN protocol that underpins its QoS capabilities: the use of acknowledgements. The authors of BIB005 showed how packet delivery was improved significantly once retransmissions were enabled in a small testbed. However, the results obtained there are not translatable to the performance of a large LoRaWAN with thousands of devices. Additionally, acknowledgements are not only used to confirm application layer packets, but several MAC commands also requires confirmation of reception and execution BIB006 . A detailed evaluation of the viability of confirmed traffic in LoRaWANs is required to better understand the QoS levels achievable with this technology. This paper contributes the following. • It discusses the IoT use cases that require confirmed traffic. • It provides an extensive survey of all the LoRaWAN literature that deals with confirmed traffic and discusses some identified common themes. • It presents the challenges that hamper the viability of confirmed traffic and proposes methods to counteract them. The rest of this paper is organised as follows. Section II discusses the various IoT use cases that require confirmed traffic. Background information on the LoRaWAN protocol as well the mechanisms enabling confirmed traffic is presented in Section III. An extensive survey on the impact of downlink traffic, with a focus on confirmed traffic, can be found in Section IV. A discussion on the surveyed work is located in Section V. Alternative methods to implement confirmed traffic is discussed in Section VI. In Section VII, the open challenges impacting the viability of confirmed traffic are discussed. Finally, the work is concluded in Section VIII.