Comparison of CRB on TOA estimation of LOS path between incoherent and coherent processing of two subbands CSI measurements

Compared with the Wi-Fi received signal strength (RSS) commonly used in indoor localization, channel state information (CSI) contains physical layer information such as amplitude and phase of each subcarrier during signal transmission. Therefore, the indoor localization based on (CSI) can achieve higher accuracy, which has been widely used. However, when bandwidth is insufficient, it is challenging to distinguish the multiple-path components in CSI. In order to further improve the estimated accuracy of the line of sight (LOS) path time of arrival (TOA), multiple subbands are considered. In this paper, the Cramer-Rao Bounds (CRBs) of multiple-path TOA estimation for coherent and non-coherent processing of two subbands are derived. In addition, a concise approximate of CRB on TOA of LOS path is given, which can directly reveal the effect of key variables, such as time delay and phase difference between two subbands. Through simulation, the performance of single subband, coherent and non-coherent processing of two subbands are compared, and the hyper-coherent effect on LOS path TOA estimation with two subbands is verified.