  Interference evaluation is crucial when deciding whether and how wireless
technologies should operate. In this paper we demonstrate the benefit of
risk-informed interference assessment to aid spectrum regulators in making
decisions, and to readily convey engineering insight. Our contributions are: we
apply, for the first time, risk assessment to a problem of inter-technology
spectrum sharing, i.e. Wi-Fi/LTE in the 5 GHz unlicensed band, and we
demonstrate that this method comprehensively quantifies the interference
impact. We perform simulations with our newly publicly-available tool and we
consider throughput degradation and fairness metrics to assess the risk for
different network densities, numbers of channels, and deployment scenarios. Our
results show that no regulatory intervention is needed to ensure harmonious
technical Wi-Fi/LTE coexistence: for the typically large number of channels
available in the 5 GHz band, the risk for Wi-Fi from LTE is negligible,
rendering policy and engineering concerns largely moot. As an engineering
insight, Wi-Fi coexists better with itself in dense, but better with LTE, in
sparse deployments. Also, both main LTE-in-unlicensed variants coexist well
with Wi-Fi in general. For LTE intra-technology inter-operator coexistence,
both variants typically coexist well in the 5 GHz band, but for dense
deployments, implementing listen-before-talk causes less interference.
