Emerging Low Power Wide Area Networks (LPWAN) represent a real breakthrough for monitoring applications, since they give the possibility to generate and transmit data over dozens of kilometers while consuming few energy. To further increase the autonomy of such wireless systems, the present paper proposes an original methodology to correctly dimension the key elements of an energy autonomous node, namely, the supercapacitor and the battery that mainly give the form factor of the node. Among the LPWAN candidates, LoRa is chosen for real field experiments with a custom wireless platform that proves its energy neutrality over a finite horizon. Different LoRa configurations are explored, leading to adequate dimensioning. As an example, it is shown that, for the same quality of service, the size of the solar panel needed to keep a LoRa node autonomous in the South of France is less than half of the size required in North of France.

LoRa is a technology for long range wireless communications that allows the development of new applications in domains such as smart agriculture, smart city or smart industry. Many in-field deployments and measurement campaigns have been performed in recent years, showing the sensibility of such communication to fading channels. In this paper, the LoRa transmission reliability is evaluated in simulations for different fading channels. Moreover, as the energy consumption also depends on the configurations, a trade-off between energy consumption and reliability needs to be considered when selecting a LoRa configuration. To this aim, experimental energy measurements are performed on a Semtech device, showing that energy difference between various configurations can reach up to two orders of magnitude. Results highlight that LoRa configuration impacts the energy/reliability trade-off and the best one strongly depends of the type of channel.

This brief proposes a new low power, low latency and low cost reconfigurable architecture for software defined radio. Due to their flexibility and reconfigurability, software defined radios are now massively used as wideband transceivers, channel sounders or network gateways. However, they often struggle to meet the desired requirements in terms of energy consumption and throughput. In this brief, we present a new architecture capable of tackling these challenges, by combining an off-the-shelf generic radio component with a low power microcontroller associated to a Fourier transform coprocessor. To prove the benefit of our approach, after describing the key assets of the architecture, we derive a complete physical layer dedicated to audio broadcast applications. This chain is capable of streaming High Definition audio stream in real time with low power (437 mW) and very low latency (854 µs). We show that our processing chain can be flawlessly run on our architecture paving the way for larger adoption of a new generation of low power low latency software defined radio architectures.