To mitigate interference in Wireless Sensor Networks (WSNs), the IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) mode offers Time Division Multiple Access (TDMA) in combination with channel hopping. While this is a simple, yet powerful mechanism, it leaves room for improvement at the face of recurrent or broad-band interference. In this paper, we propose a scheduling function called Scheduling Function with Soft Blacklisting (SFSB), which utilizes the 6top sublayer. By that, it integrates into the 6TiSCH stack as specified by the respective Working Group of the Internet Engineering Task Force (IETF). SFSB mitigates interference by sensing the spectrum for interference and locally blacklisting channels to be found under interference from other co-located networks. Blacklists are shared among 1-hop neighbors and are used to suspend communication or divert to a non-disturbed channel. By leveraging existing standards, the deployment in WSNs is simplified and interoperability is ensured. We evaluate our proposal through simulations. First results suggest that the localized interference mitigation has an advantage when nodes are subject to heavy interference.
