Using Chinese Remainder Theorem for the Grouping of RFID Tags

<p>In this paper, we propose a novel scheme for the design of grouping of radio-frequency identification (RFID) tags, based on the Chinese remainder theorem (CRT). Grouping allows verifying the integrity of a collection of objects without the requirement for accessing external systems, and can be extended to identify missing objects. Motivated by the redundancy property of the Chinese remainderrepresentation, we propose grouping of RFID tags via the CRT. The proposed scheme not only provides designated decoding guarantees, but also offers flexibility in constructing group generation matrices. We also characterize the key objects needed to study decoding guarantees of grouping and its extended counterpart, called rank-deficient and dead-end sets, respectively, which enable theoretical analyses of error rates. The two key objects are related to the minimum and stopping distances of a linear code, respectively. As such, the characterization offers direct connection with coding theory that helps in the understanding of the verification/identification problems being studied. Theoretical and simulation results are presented, demonstrating that the proposed scheme is an efficient approach to the design of grouping of RFID tags.</p

Robust Design of Two-Dimensional Optical Reference Signals Against Diffraction Effects

<p>This paper presents two novel approaches to the design of two-dimensional (2-D) optical zero reference signals (ZRSs) that are robust against diffraction effects based on the parametric minimum cross-entropy (PMCE) method. Grating alignment systems require a 2-D optical ZRS to perform absolute measurements. A common method of acquiring 2-D optical ZRSs involves illuminating two identical superimposed 2-D zero reference codes (ZRCs). The output signal is the 2-D optical ZRS and can be represented as the autocorrelation of the 2-D ZRC transmittance. In ultrahigh-resolution systems, diffraction distorts the shadow of the first 2-D ZRC, degrading the autocorrelation and greatly reducing the amplitude of the 2-D optical ZRS. To improve the robustness of 2-D optical ZRSs against diffraction effects, this paper formulates two combinatorial optimization problems for the design of 2-D ZRCs with minimum diffraction effects: one of which is a maximization problem, and the other a minimization problem. Aiming at solving the two problems, this study proposes two schemes based on the PMCE method to search for an optimal 2-D ZRC. Simulation results reveal that there are 3.36-8.34% increases in the slope of the central peak of a 2-D optical ZRS and that there are 16.12-20.90% increases in the sum of the slope of the central peak and the effective signal amplitude of a 2-D optical ZRS, as compared with those obtained by the recently proposed cross-entropy method. The proposed PMCE-based schemes prove to search for 2-D ZRCs more effectively than existing solutions, while requiring less computational complexity.</p

Grouping of RFID Tags via Strongly Selective Families

This letter proposes a novel scheme for grouping of radio-frequency identification (RFID) tags, based on strongly selective families (SSFs). Grouping of RFID tags allows verifying the integrity of groups of objects without external systems such as databases or verifiers, and can be extended to identify missing objects. The existing scheme is based on Gallager's low-density parity-check (LDPC) codes and, as such, it cannot easily achieve designated decoding guarantees due to its pseudo-random nature. Motivated by the strongly selective property of SSFs, this study proposes grouping of RFID tags via SSFs, such that designated decoding guarantees are more easily achieved. Simulation and theoretical results are presented, demonstrating that the proposed scheme can greatly improve the performance of the existing one.</p