2.4 - Characterisation of Channel Usage in ISM/SRD Bands

Spectrum occupancy measurements for sub-GHz unlicensed frequency bands at two distinct inner city locations are presented in this paper. Short time measurements of spectrum utilization in three different bands are followed by a long-term observation of a selected sub-band over 7 days. The antenna in the latter measurement has an exposed position, which is typical for a fixed base station of a data aggregation network. For a selected frequency range, important signal characteristics (e.g. signal durations and inter-arrival times) are obtained and utilized to parameterise a proposed interference model. This analytic model accurately describes the collision probability of a packet transmission in the considered channel.