Perceiving Accurate CSI From OFDM Signals for Microwave Ranging and Localization

Sensing is a critical aspect of wireless networks, used in applications such as localization, tracking, and human-computer interaction. However, prevalent commercial networks, such as WiFi, suffer from a lack of strict time synchronization between terminals and access points (APs). This leads to the introduction of phase errors in channel state information (CSI), hindering the effective utilization of sensing technology. To obtain accurate CSI with synchronization performance from orthogonal frequency division multiplexing (OFDM) signals, we propose a method that eliminates phase errors using the bidirectional channel. However, this approach only yields the square of the true channel, which includes fake multipath and disrupts the two-way channel. To recover the true channel, we introduce a channel recovery algorithm based on swarm optimization. Our proposed approach is validated through simulations and the use of software-defined radios (SDRs) in real-world measurements. The results show that accurate CSI can be acquired without phase errors, enabling the estimation of the true path after executing the CSI recovery algorithm. We demonstrate the effectiveness of our proposed method for perceiving accurate CSI in practical scenarios using a localization application.