Towards an Automated Monitoring of RF Activity in Low-Power Wireless Testbeds

To rigorously benchmark the performance of low-power wireless protocols, it is essential to monitor and quantify the RF activity in agiven testing environment. Indeed, unwanted radio interference inthe surroundings of wireless nodes may worsen their communication performance. Similarly, an inconsistent RF noise across multiple test runs may prevent the ability tofairly compare their results. Unfortunately, to date, this aspect is often neglected by the community, especially due to the lack of monitoring tools enablinga quantitative assessment of RF activity in large testing facilities. In this paper, we move the first steps towards the creation of a low-cost tool automating the distributed monitoring of RF usage in a low-power wireless testbed. Specifically, we first instrumentthe latest generation Raspberry Pi devices to sense any ongoing activity on the RF channel, enabling a functionality that is typically not available on off-the-shelf Wi-Fi hardware. We then show that one can synchronize the RF measurements of multiple Raspberry Pi connected to a common Ethernet backbone with an average error below 200휇s. We further devise exemplary strategies to quantify the difference in RF activity across test runs, and enable the real-time detection of deviations in the current RF channel usage compared towhat was measured in earlier runs. We finally showcase the ability to compare the RF activity during several test runs and detect when additional interference was present in the environment, as well as when diverse interference patterns were artificially generated.