International audienceLong-range low-power communications are starting to replace short-range low-power communications in monitoring applications based on wireless sensor networks, both in rural and urban environments, due to the small deployment cost of long-range technologies. In this paper, we focus on the MAC layer of the recent LoRaWAN (long-range wide area network) standard, and specifically on the on-the-air activation procedure, which defines how nodes join an existing network. We propose a Markov chain model of the on-the-air activation, and we derive the expected delay and the expected energy required to join the network. We analyze the impact of several parameters on these metrics, including traffic conditions, duty cycles, and channel availability. We also discuss the impact of the regional settings of the standard. To the best of our knowledge, this is the first analysis of the MAC layer of LoRaWAN

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Estimating a radio link quality for WSNs "Wireless Sensor Networks" becomes a big challenge when these networks are deployed in harsh or hostile environment. The quality of a radio link is a useful information for higher layer protocols as it has an impact on the network performance. The harsh or hostile outdoor conditions have a strong impact on signal propagation and make communication difficult or unreliable. Hence, deploying a wireless sensor network in such an environment requires a full knowledge of radio channel characteristics provided by the hardware designed to tackle the deployment. This paper describes a novel experimental testbed platform and a method to estimate the radio link quality and to determine WSN deployment parameters by using nodes shaped to the monitored site. The objective is to design a platform, independent from the environment, that can be used to estimate the radio link quality independently from the deployment context. This SDR "software defined radio" based solution will be used in this paper to estimate the parameters of an overwater radio link.