In this paper, we investigate a localization performance based on channel state information (CSI) of separated antenna. In multi-carrier transmission system, CSI has been considered as one of the promising signatures of radio frequency (RF) channel and employed to device localization. However, CSI can be correlated in typical indoor environment which may limit the unique representations of the signature for RF fingerprinting. To solve this, we propose a joint CSI-based device localization, exploiting the diversity of RF signatures. Even if the one CSI loses the reliability as a the fingerprint due to spatial correlation, the other CSI can support the device localization performance. For experimental evaluation, we construct the test-bed and confirmed the proposed scheme can support single CSI-based localization even if highly correlated CSI are reproduced occasionally at many locations. The test results in indoor environment show that the proposed scheme complements the single-CSI in terms of the reliability of authentication with localization of the devices.