Abstract:

Recently, there has been wide interest in RFID (Radio Frequency Identification). With increasing applications of RFID technology, reliability requirements for deployment of RFID readers have become more critical. For a robust deployment of RFID network, a systematic solution was proposed in this study. Firstly, the performance of RFID was estimated statistically. Referring to Taguchi method, an experimental design was designed for finding out the factors which affect the reading rate of RFID significantly. The content in the chest (the tag attachment) and the direction of tags were obtained to be important causes for practical RFID applications. Another experiment for RFID interrogation zone was performed by applying Response Surface Method. Based on the significant factors and adding a new factor “tag density”, interrogation range models for 915MHz and 2.45GHz were constructed respectively. Hence, the size and shape of interrogation zone for various scenarios could be quickly estimated by the constructed models.

Secondly, the interrogation zone was measured in practice. The measured point was set in the center of a cube and the cubes spread uniformly on each layer. By moving the tag cube by cube, layer by layer and assuming the performance of the tag is homogenous in each grid, the result was plotted and used to describe the shape of a RFID antenna’s interrogation zone. To simplify the reader deployment problem, instead of the traditional 2D circle-like shape assumption, the ellipse/ellipsoid-like shape was taken to represent the signal range of an RFID antenna in this study. It is more flexible and fitting for practicability than the traditional way.

Thirdly, a deployment tool was designed for users to obtain a recommended layout. For a given area, solutions of number and placement of RFID readers are computed fast and robustly. Under input constraints, the system suggests a proper deployment for users to reach a high reading rate and ensure a complete coverage. In addition, two simplified mechanisms were provided for users to avoid reader collision which may result in low efficiency of a RFID network. Finally, the practical implementation and simulations were performed to test the practicability of the deployment tool and further to confirm the robustness and adequacy of the proposed models.