High resolution temporal occupancy measurements to characterize idle time window in ISM band

Cognitive radios are designed to access unused spectrum opportunistically by limiting interference to primary users in frequency, space or in time dimensions. Finding and accessing spectrum opportunities in the time domain in real environment is very challenging, particularly in the ISM band due to the presence of hopped and short duration signals. In this paper, implementation details of a measuring system are presented which allow the capture of various signals having durations of 204.8 μsec over the full ISM bandwidth. Moreover, the effect of time resolution is illustrated on the statistic of idle time window for opportunistic spectrum access in the time domain.