RFSoC-Based Transceiver Design for Wideband Channel State Information Acquisition

Channel state information (CSI), originally defined to compensate for distortions in the channel caused by factors such as multipath and to restore transmitted message signals, has since been widely utilized in applications like positioning and sensing due to its ability to identify propagation channel characteristics between the transmitter and receiver, thereby enabling environmental awareness. Furthermore, since channel characteristics can be estimated precisely as the bandwidth of the transmitted and received signals increases, we developed a system to acquire CSI using signals with bandwidths of up to 320 MHz, as specified by the IEEE 802.11be standard, commonly known as Wi-Fi 7. The method of modifying the commercial Wi-Fi modem firmware to obtain CSI requires expert knowledge of firmware, and the development process is complex and has limitations that make it difficult for a typical researcher to perform in practice. To overcome this limitation, we have implemented hardware and software that operate in a software-defined radio (SDR) manner using an RFSoC (radio frequency system on chip) board, and through field experiments, we confirmed that it is possible to acquire CSI corresponding to each bandwidth by transmitting and receiving signals with bandwidths of 20, 40, 80, 160, and 320 MHz. In addition, experimental measurements verified that the characteristics of the estimated channel state varies based on the presence or absence of a line-of-sight (LOS) path between the transmitter and receiver. These findings demonstrate that our system can be utilized to develop future positioning and sensing technologies using Wi-Fi 7. In particular, this paper provides a detailed description of the hardware manufacturing process, which is expected to contribute to the construction of a Wi-Fi standard-compliant system that supports the transmission and reception of signals with a wider bandwidth in the future.