Experimental Accuracy Comparison for 2.4GHz and 5GHz WiFi Sensing Systems

With the increasing popularity of WiFi in recent years, WiFi-based wireless sensing technologies have attracted tremendous research. As commercial WiFi networks transition from the 2.4GHz band into the 5GHz band, no prior work has explicitly investigated the impact that this choice of frequency has on sensing outcomes. On both frequency bands, this paper uses the frequency selective behaviour of CSI and a support vector machine classifier to verify the accuracy of human surveillance applications. These experiments demonstrate that 5GHz WiFi offers superior sensing outcomes, with a 6% increase in human occupancy counting accuracy. By restricting the domain of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers, we perform further experiments to conclude that the increase in accuracy is primarily a result of having the higher number of subcarriers or the larger bandwidth for 5GHz WiFi. To corroborate the robustness of our sensing system, we conduct the experiments over multiple trials for two very different environments; one being a controlled elevator setup, while the other being a more realistic and uncontrolled, office space. This novel experimental investigation motivates the need for conducting more comparison studies across the electromagnetic spectrum to identify the application specific best frequency spectrum for the next generation of wireless sensing technologies.