Spectrum Occupancy Measurements and Analysis in 2.4 GHz WLAN

High time resolution spectrum occupancy measurements and analysis are presented for
2.4 GHz WLAN signals. A custom-designed wideband sensing engine records the received power
of signals, and its performance is presented to select the decision threshold required to define the
channel state (busy/idle). Two sets of measurements are presented where data were collected using
an omni-directional and directional antenna in an indoor environment. Statistics of the idle time
windows in the 2.4 GHz WLAN are analyzed using a wider set of distributions, which require fewer
parameters to compute and are more practical for implementation compared to the widely-used
phase type or Gaussian mixture distributions. For the omni-directional antenna, it was found that the
lognormal and gamma distributions can be used to model the behavior of the idle time windows
under different network traffic loads. In addition, the measurements show that the low time resolution and angle of arrival affect the statistics of the idle time windows.