On the Coding of Chipless Tags

It is believed that chipless tags, often printable, will play a fundamental role for radio frequency identification technology to replace the currently widely used barcode technology. An application scenario of chipless tags that raises concerns is that the object attached with a chipless tag can be bent and even folded or crumbled. In this case, it is very difficult to identify the tag identity (ID) since some peaks or notches, which reflect the information encoded in the tag ID, in the radar cross section of the tag may disappear. In this paper, we propose to insert some error-correcting bits to the code of tag ID to improve the reliability of identifying chipless tag IDs. An error-detection channel model for dealing with this problem is developed. It is found that the channel model is asymmetric. Several error-correcting codes, namely Golay, BCH, and majority-rule-based multiple interrogations, are proposed to apply to the chipless tag encoding/decoding problem. Some performance indices of these codes, namely successful reading rate and expected successful interrogation times, are analyzed. The asymmetric property of the channel model entails the performance analysis to be conducted in a different way from the literature. Numerical and simulation results are presented to show the effectiveness of the proposed methods.