WiFi Frequency Utilization Analysis by SpectrumMap Database

摘要

We have proposed a SpectrumMap database [1] to provide the public with the general knowledge of radio frequency usages in the downtown Tokyo. Several spectrum measurement campaigns using a simple radiometer have been conducted to provide understanding of primary signals' activities. This paper shows the spectrum occupancy of WiFi frequency band using this database. Different from other spectrum measurements, we perform WiFi spectrum data collections in a rich diversity of scenarios, including residences, bustling areas and business districts; and the measurement schedule is designed to meet human lifestyles, such as commuting, working or evening hours on weekdays and weekends. The WiFi spectrum occupancy is measured by the duty cycles, the threshold of which is estimated by a Gaussian distribution model for the WiFi band noise. The average and standard deviation are derived by a linear interpolation from those of the adjacent noise channels. Important observations obtained from this study are: (1) The average of the overall utilization of WiFi spectrum band is lower than 5.11%; (2) Two good non-overlapping channels (CHI, CH11) are found for spectrum reuse in city center environment by showing their superiorities in channel occupancy rates and availabilities; (3) The long idle time is observed frequently even for these active channels. The result is expected to highlight the effectiveness of this kind of grass-roots spectrum collections with simple radiometers for the analysis of potential spectrum sharing.