Licentiate thesis 2018-004

Robustness in Low Power Wide Area Networks

Charalampos Orfanidis

14 June 2018


During the past few years we have witnessed an emergence of Wide Area Networks in the Internet of Things area. There are several new technologies like LoRa, Wi-SUN, Sigfox, that offer long range communication and low power for low-bitrate applications. These new technologies enable new application scenarios, such as smart cities, smart agriculture, and many more. However, when these networks co-exist in the same frequency band, they may cause problems to each other since they are heterogeneous and independent. Therefore it is very likely to have frame collisions between the different networks.

In this thesis we first explore how tolerant these networks are to Cross Technology Interference (CTI). CTI can be described as the interference from heterogeneous wireless technologies that share the same frequency band and is able to affect the robustness and reliability of the network. In particular, we select two of them, LoRa and Wi-SUN and carry out a series of experiments with real hardware using several configurations. In this way, we quantify the tolerance of cross technology interference of each network against the other as well as which configuration settings are important.

The next thing we explored is how well channel sensing mechanisms can detect the other network technologies and how they can be improved. For exploring these aspects, we used the default Clear Channel Assessment (CCA) mechanism of Wi-SUN against LoRa interference and we evaluated how accurate it is. We also improved this mechanism in order to have higher accuracy detection against LoRa interference.

Finally, we propose an architecture for WSNs which will enable flexible re-configuration of the nodes. The idea is based on Software Defined Network (SDN) principles and could help on our case by re-configuring a node in order to mitigate the cross-technology interference from other networks.

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