Qiulin Huang

An Enhanced Binary Anti-Collision Algorithm of Backtracking in RFID System

AN ENHANCED BINARY ANTI-COLLISIONALGORITHM OF BACKTRACKING IN RFID SYSTEMX.-L. Shi, X.-W. Shi, Q.-L. Huang, and F. WeiNational Key Laboratory of Antennas and Microwave TechnologyXidian UniversityXi’an 710071, P. R. ChinaAbstract—On the base of the binary search algorithm of backtrack-ing, an enhanced binary anti-collision search algorithm for radio fre-quency identification (RFID) system is presented in this paper. Withthe method of transferring the collision bit in place of the ID of thetag, the proposed algorithm can improve identification efficiency sig-nificantly. Mathematical simulation result shows that compared withthe binary search algorithm, dynamic binary search algorithm and thebinary search algorithm of backtracking, the proposed algorithm out-performs the three algorithms previous when handling multiple RFIDtags simultaneously.1. INTRODUCTIONRadio frequency identification (RFID) system is a contact-lessautomatic identification system. Now it has received much attention inmany industries like manufacturing companies, material flow systems,etc. Compared with the barcode, a RFID system has many merits asfollows [1]:A. The information stored in a tag is much larger than that in abarcode.B. The information stored in tags can be reprogrammed and tags canbe used repeatedly.C. A tag has a much longer life than a barcode especially when theworking condition is extremely bad.D. When there is a barrier in front of a barcode, the barcode can notbe read by a reader, but a tag can be read due to the differentworking styles.

Design of Compact Quad-Frequency Impedance Transformer Using Two-Section Coupled Line

This paper presents a compact quad-frequency impedance transformer that is composed of a two-section coupled line to achieve ideal impedance matching at three arbitrary frequencies and a related frequency. The exact closed-form equations and design procedures are given based on strict theoretical analysis. After demonstrating the bandwidth performance and symmetry properties of different impedance transform ratios, we fabricated a circuit to show the validity of practical applications. Good agreement between the measured data and anticipated results is achieved.

Mutual Coupling Calibration for Microstrip Antenna Arrays via Element Pattern Reconstruction Method

The element pattern reconstruction method is introduced to calibrate the mutual coupling effect of the microstrip arrays. This method is based on the fact that if the reconstructed pattern of the embedded element is consistent with that in the isolated state, then the corresponding calibrated received signal will be consistent with the received signal without mutual coupling effect. The calibration matrix is developed and is employed in the microstrip array to reconstruct the element patterns and in the direction-of-arrival (DOA) estimations. The new method has a wide adaptability for element structures and is very effective for the microstrip antenna array. Effectiveness of the new method is verified by the numerical examples.

Accurate DOA Estimations Using Microstrip Adaptive Arrays in the Presence of Mutual Coupling Effect

A new mutual coupling calibration method is proposed for adaptive antenna arrays and is employed in the DOA estimations to calibrate the received signals. The new method is developed via the transformation between the embedded element patterns and the isolated element patterns. The new method is characterized by the wide adaptability of element structures such as dipole arrays and microstrip arrays. Additionally, the new method is suitable not only for the linear polarization but also for the circular polarization. It is shown that accurate calibration of the mutual coupling can be obtained for the incident signals in the 3 dB beam width and the wider angle range, and, consequently, accurate [1D] and [2D] DOA estimations can be obtained. Effectiveness of the new calibration method is verified by a linearly polarized microstrip ULA, a circularly polarized microstrip ULA, and a circularly polarized microstrip UCA.

Novel Binary Search Algorithm of Backtracking for RFID Tag Anti-Collision

In RFID system, tag collision is a main problem for fast tag identification. On the base of binary search algorithm of backtracking, an enhanced binary anti-collision search algorithm for radio frequency identification (RFID) system is presented in this paper. By dynamically transferring the ID of the tag, the length of the data transferred can be decreased dramatically. Mathematical simulation result shows that compared with the binary search algorithm of backtracking, the proposed algorithm can save channel by more than 43.75% when handling multiple RFID tags simultaneously. Finally the proposed algorithm is successfully applied to a RFID device, which validates itself.

A CPW-fed slotted antenna with loaded split ring for multiband applications

This paper presents a coplanar waveguide (CPW)-fed slot antenna consisting of a slotted ground and a parasitically coupled split ring for multiband operation. In the design, the use of both the loaded split ring to rectangle wide slot and embedded L-slots into the ground is found an effective skill for exciting multiresonant modes as well as miniaturizing the slot antenna. The numerical and experimental results show that the optimal antenna has triple operating bands below – 10-dB reflection coefficients magnitude |S 11|) centered at 2.4/3.5/5.8 GHz covering the required bandwidths of various wireless communication standards. In addition, stable monopole-like radiation patterns and acceptable antenna gains are achieved across the operating bands.

Compact Multiband Slot Antenna for WLAN/WiMAX Operations

A novel compact triple-band slot antenna is proposed for WLAN/WiMAX applications. With the use of three L-shaped slots and an open-ended slot on the ground plane, three resonant modes centered at 2.4/3.5/5.8 GHz are excited. These modes cover the standards of 3.5 GHz WiMAX and 2.4/5.8 GHz WLAN, three useful frequency bands for present wireless communication systems. The proposed antenna fed by L-shaped microstrip line has a small overall dimension of mm2. The numerical and experimental results show that acceptable radiation characteristic is obtained over the operating bands.

A New Wideband Mutual Coupling Compensation Method for Adaptive Arrays Based on Element Pattern Reconstruction

A new mutual coupling compensation method for wideband adaptive arrays is proposed. The new method is developed by combining the element pattern reconstruction method and the system identification method. The element pattern reconstruction method is valid and effective in the mutual coupling compensation for adaptive arrays such as dipole arrays and microstrip arrays. Each entry of the wideband compensation matrix is represented as an analytical expression against frequency. The polynomial coefficients and orders of all entries are obtained via the system identification method. The new wideband compensation method is characterized by the good adaptability of element structures and polarizations owing to the advantages of element pattern reconstruction method. A wideband microstrip array is designed to test the validity and effectiveness of the wideband compensation method.

Channel capacity of indoor MIMO systems in the presence of polarization diversity

Typical indoor wireless channel is Ricean fading, and can be decomposed into the sum of an LOS propagation channel and a scattering channel. We assumed the scattering channel is Rayleigh. Understanding of polarization, we derived the LOS propagation channel model in the presence of polarization diversity. Following above, we proposed the MIMO channel when polarization diversity is present. We show that polarization diversity can increase MIMO channel capacity effectively.

Calibration of Mutual Coupling Effect for Adaptive Arrays Composed of Circularly Polarized Microstrip Antennas

Abstract In this article, a new mutual coupling calibration method, the element pattern reconstruction method, is proposed and utilized to calibrate the mutual coupling effect of circularly polarized microstrip arrays. Previous work has verified that the new calibration method is suitable for arrays composed of not only wire elements but also linearly polarized microstrip elements. The mutual coupling calibration of circularly polarized microstrip arrays employing the new method is presented in this work. For a well-designed circularly polarized microstrip array, the calibration matrix for the main polarization component can be used to calibrate the received signals with high accuracy. The numerical results verify the effectiveness of the new calibration method for the circularly polarized microstrip arrays.