A 3D Ray-tracing Model for UHF RFID

Abstract

In this work, a 3-dimensional (3D) ray-tracing model is proposed. The model is specifically tailored for RFID applications by taking into account some of its unique characteristics. The proposed model can give accurate power predictions and is suitable for indoor RFID systems operating with low fade margins. The model has been verified by comparison with Method of Moments (MoM) and practical measurements. It is shown to achieve a high accuracy with significantly less computational complexity than MoM. An example application of the model is presented comparing the performance of two antennas with similar beam patterns but different axial ratio. The predicted tag detection rates (63% and 50%) are in good agreement with the experimental data (65% and 55%), showing the accuracy of the model and its improvement over previous models which are not able to handle axial ratio as accurately.

Simulation of Radio Signal Propagation for UHF RFID Technology in an Indoor Environment Using Ray Tracing (Graphics) Method

“…RFID applications [1][2][3][4][5][6][7][8] Practical use RFID implementation [9][10][11][12] Difficulties of UHF RFID implementation Empirical methods [16,17] Inaccuracy is increased with specific forms of the environment (e.g., corridors) Deterministic methods [18][19][20]31] Computationally demanding depending on the number of walls and obstacles Ray tracing (physics) [15,[21][22][23][24][25][26][27][28][29][30]32,33] Calculation time increases with an increasing number of rays, inaccuracy in the calculation may occur due to the different number of incident rays Commercially available SW [21,22,[34][35][36][37] Some of the frequently used tools…”

“…Over the last decades, several methods have been proposed to simulate the propagation of electromagnetic waves ranging from extremely low-frequency (ELF) [13] to terahertz waves [14]. The authors of article [15] divide these methods into three categories: empirical methods, deterministic methods (full-wave simulation) and ray tracing. Empirical methods, such as One-Slope [16], Dual-Slope [16], COST-231 [16] or Okumura-Hata [17], are based on a large number of measurements but may be inaccurate in the case of atypical spaces.…”

“…Empirical methods, such as One-Slope [16], Dual-Slope [16], COST-231 [16] or Okumura-Hata [17], are based on a large number of measurements but may be inaccurate in the case of atypical spaces. For the application of RFID deployment in an indoor area, these methods lack spatial information and energy changes due to multipath propagation, which is very important for defining the tag readability area [15]. Among the deterministic methods, Method of Moments (MoM) [18], Finite-Difference Time-Domain (FDTD) numerical method [19] and Finite Integration Technique (FIT) numerical method [20] are mentioned.…”

“…Among the deterministic methods, Method of Moments (MoM) [18], Finite-Difference Time-Domain (FDTD) numerical method [19] and Finite Integration Technique (FIT) numerical method [20] are mentioned. These methods are accurate but are computationally complex and time-consuming [15]. As a compromise, the now widely used deterministic method ray tracing [15,[21][22][23][24][25][26][27][28][29][30], more precisely, ray tracing (physics) (RT), is based on geometrical optics (GO).…”

“…These methods are accurate but are computationally complex and time-consuming [15]. As a compromise, the now widely used deterministic method ray tracing [15,[21][22][23][24][25][26][27][28][29][30], more precisely, ray tracing (physics) (RT), is based on geometrical optics (GO). It is usable as an approximated method to estimate the intensity of an electromagnetic field [21].…”