Indoor Wireless Localization Based On Channel State Information

In the conventional indoor localization scheme, Received Signal Strength Indicator(RSSI) is widely used for its accessibility. However, subject to the multipath effect in the indoor environment, the localization accuracy based on RSSI is not ideal. Breaking-through techniques resort to finer-grained wireless channel measurement. Different from RSSI, the PHY layer power feature, channel response, is able to better indicate the channel characteristics, thus holds the potential for the convergence of accurate and pervasive indoor localization. In this paper, both the Channel State Information’s(CSI, reflecting channel response in 802.11n) extraction process and characteristics are studied with commercial 802.11 n wireless network. According to the CSI’s property, we design the CSI-based crowd counting system and passive indoor localization system. The experimental results show that both these systems can good meet the expectations.In this paper, the contribution includes the following:(1) Researching the RSSI-based localization scheme and indicating the RSSI’s shortcomings in indoor localization. Then we introduce the CSI.(2) We compare the CSI and RSSI, and analyze the characteristics of the CSI. Then, we find that CSI will change as the environment changes and tends to be stable in a stable environment.(3) According to the CSI’s characteristic, we design the CSI-based crowd counting system. In this system, we develop the expansion matrix algorithm to calculate the expansion percentage of the matrix that we concern. After getting the expansion percentage, we complete the crowd counting task by using the dynamically updated fingerprint database.(4) According to the CSI’s another characteristic, we design the CSI-based passive indoorlocalization system. In order to achieve the passive indoor localization in a certain range, all of the locations’ data are recorded in the fingerprint database for comparison using the Earth Mover’s Distance(EMD) measure.(5) By the using of the simulation tools, the performance of the above-described systems is analyzed.