Measurement and Analysis of Radio Frequency Interference in the UWB Spectrum

Ultra-wide band (UWB) radio systems are expected to operate in co-existence with a myriad of other systems over a large unlicensed bandwidth. Thus, UWB devices need to incorporate efficient inter-system interference mitigation mechanisms. In this paper, we present interference measurements covering the UWB spectrum from 3 GHz to 11 GHz conducted at two locations (indoor and outdoor) on the campus of Aalborg University, Denmark. We analysed the measurements in terms of occurrence probability, interference power distribution and inter-arrival time statistics. The goal is to understand the characteristics of signals emanating from systems operating on this ultra-wide bandwidth as a basis for the development of models and methods for interference characterization and mitigation. Results indicate that signal activity vary significantly across the spectrum with the 5 GHz - 6 GHz and 9 GHz - 10 GHz sub-bands having the strongest power levels in the indoor and outdoor measurements, respectively. Statistical analysis results further show significant variation of the power distribution, occurrence probability and inter-arrival time statistics for the various signals detected in the measurements. Results also show that time between interference occurrence is exponentially distributed for most of the sources.