A practical RFID authentication mechanism for digital television

As information technology continuously progresses, more applied technologies are developed, such as radio frequency identification (RFID). In this paper, we propose a novel digital television (DTV) structure that uses RFID for encryption. RFID is widely used for various applications because of its advantages such as an extended lifetime and security, and it is less affected by environmental constraints. The proposed protocol uses RFID for encryption to withstand many attacks that the traditional system is vulnerable to, such as impersonation attack, replay attack and smart card cloning. Compared with other protocols, the proposed protocol is more secure and efficient. Thus, our proposed protocol makes the DTV framework more complete and secure.     

Simultaneous prediction of density and moisture content of wood by terahertz time domain spectroscopy

In this study, demonstration of simultaneous prediction of solid wood density and moisture content, both of which are critical in manufacturing operations, of 4 species (Aspen, Birch, Hemlock and Maple) was accomplished using terahertz time-domain spectroscopy (THz-TDS). THz measurements of wood at various moisture contents were taken for two orientations of the THz field (parallel and perpendicular) with respect to the visible grain. The real and imaginary parts of the dielectric function averaged over the frequency range of 0.1 to 0.2 THz had strong correlation with density and moisture content of the wood. We extend a model that has been applied previously to oven-dry wood to include the effects of moisture below the fiber saturation point by combining two effective medium models, which allows the dielectric function of water, air and oven-dry cell wall material to be modeled to give an effective dielectric function for the wood. A strong correlation between measured and predicted values for density and moisture content were observed.     

Improved Hydrogen Capping Effect in n-Type Crystalline Silicon Solar Cells by SiN(Si-Rich)/SiN(N-Rich) Stacked Passivation

The effect of hydrogen capping of SiN(Si-rich)/SiN(N-rich) stacks for n-type c-Si solar cells was investigated. Use of a passivation layer consisting of Si-rich SiN with a refractive index (n) of 2.7 and N-rich SiN with a refractive index of 2.1 improved the thermal stability. A single SiN passivation layer with a refractive index of 2.05 resulted in an initial lifetime of 200 μs whereas the layer with a refractive index of 2.7 resulted in a high initial lifetime of 2 ms, but the layer degraded rapidly after firing. A stacked passivation layer with refractive indices of 2.1 and 2.7 had a stable lifetime of 1.5 ms with an implied open-circuit voltage (iV _oc) of 720 mV after firing. The thermally stable passivation mechanism with changing amounts of Si–N and Si–H bonding was analyzed by Fourier-transform infrared (FTIR) spectroscopy. Incorporation of the SiN _x stack layer (2.7 + 2.1) into the passivated rear of n-type Cz silicon screen-printed solar cells resulted in energy conversion efficiency of 19.69%. Improved internal quantum efficiency in the long-wavelength range above 900 nm, with V _oc of 630 mV, is mainly because of superior passivation of the rear surface compared with conventional solar cells.     

Terahertz polarization beam splitter based on photonic crystal and multimode interference

We design a compact terahertz （THz） polarization beam splitter. Both plane wave expansion method and fi- nite-difference time-domain method are used to calculate and analyze the characteristics of the proposed device. The designed polarization beam splitter can split TE-polarized and TM-polarized THz waves into different propagation di- rections. The simulation results show that the extinction ratios are larger than 18.36 dB for TE polarization and 13.35 dB for TM polarization in the frequency range from 1.86 THz to 1.91 THz, respectively. The designed polarization beam splitter has the advantages of small size and compact structure with a total size of 4.825 mm×0.400 mm.     

Sample Thickness Measurement with THz-TDS: Resolution and Implications

The accuracy of any measurement with terahertz time-domain spectroscopy (THz-TDS) depends strongly on knowing and supplying the precise sample thickness when processing the raw terahertz data. Sample thickness usually is estimated using other (non-THz) metrology and invariably involves some degree of uncertainty. It turns out that the terahertz data itself typically also contains information regarding sample thickness. However, there is limited systematic work addressing the following questions: What is the best method for extracting sample thickness from THz-TDS data? And, what is the thickness resolution obtainable with THz-TDS? In this study we demonstrate how these questions can be answered in general by answering them for a specific example: undoped silicon wafers. We determine the accuracy with which the exact thickness of nominally 500 μm silicon wafers can be measured using transmission mode THz-TDS. We analyze and compare the resolution of 5 different approaches for determining sample thickness using THz-TDS data, including two new methods and three methods proposed in the literature. The quantitative results and analyses of methods we present will be useful in developing far-infrared optical metrology. Conversely the quantitative results presented can be used to relate uncertainty in sample thickness to uncertainty in the measured terahertz data both in the time domain and frequency domain (phase and amplitude). Finally, a precise understanding of the relationship between sample thickness and THz-TDS data can be used to formulate superior THz-TDS data work-up methodologies.     

Characterization of in-situ terahertz detection by optical interaction in a periodically poled stoichiometric lithium tantalate nonlinear crystal

Terahertz waves are generated using a femtosecond laser pulse in a periodically poled stoichiometric lithium tantalate crystal and simultaneously detected via a non-collinear optical parametric interaction inside the same crystal. Real time up-conversion signal between the generated THz and an optic probe pulses is measured depending on the beam overlapped conditions using a general silicon-photodiode for the THz detection. The non-collinear geometry is to facilitate manipulated property of the position-dependent bandwidth at narrow and broad bandwidths of 45 GHz and 3.3 THz, respectively at the one crystal. Furthermore, an aperture effect at the detection part is characterized as the function of size and position owing to the spatial distribution of the frequency conversion signal and it is applied in optimization of the in-situ detection scheme.     

Optical Properties of 3D Printable Plastics in the THz Regime and their Application for 3D Printed THz Optics

We characterize the terahertz (THz) properties of several materials which can be used for fused material deposition 3D printing. We identify Polystyrene as a material which shows a promising compromise between printability and THz transparency. Furthermore, printed THz lenses are presented and characterized.     

Terahertz Spectra of L-Ascorbic Acid and Thiamine Hydrochloride Studied by Terahertz Spectroscopy and Density Functional Theory

We have investigated the terahertz spectra of L-ascorbic acid and thiamine hydrochloride measured by terahertz time-domain spectroscopy (THz-TDS) and Fourier transform infrared spectroscopy (FTIR). The measured absorption spectra were demonstrated to be in good agreement with the results simulated by Density Functional Theory (DFT) using hybrid functional B3LYP with basis set of 6-31G (d), except with slight frequency shift and few peaks missing. We presented the comparison of measured spectra by the FTIR spectroscopy employing low temperature silicon bolometer as detector and the TDS system. The measured spectra of the L-ascorbic acid showed shoulder bands at 0.25, 1.1, 1.5, 1.82, 2.03, 2.30, 2.44, 2.67, 2.97, 3.12, and 3.40 THz, respectively. The spectra of the thiamine hydrochloride show shoulder bands at 0.48, 1.11, 1.57, 1.75, 1.92, 2.08, 2.31, 2.53, 2.69, 2.85, 3.12, 3.22, and 3.31 THz. Most absorption peaks of the two samples agree with the results simulated by Density Function Theory (DFT) method of Gaussian 09 software. In our work, more spectral peaks based on experimental and theoretical results were found in comparison to that of other groups, since we employed higher sensitive FTIR measurement system and considered the effect of number of molecule unit in simulation. The study suggests that the effect of intermolecular vibration is stronger than intramolecular interaction on the absorption bands in THz region.     

Electrical Characteristics of Al/Poly(methyl methacrylate)/p-Si Schottky Device

Al/Poly(methyl methacrylate)(PMMA)/p-Si organic Schottky devices were fabricated on a p-Si semiconductor wafer by spin coating of PMMA solution. The capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of Al/PMMA/p-Si structures have been investigated in the frequency range of 1 kHz–10 MHz at room temperature. The diode parameters such as ideality factor, series resistance and barrier height were calculated from the forward bias current–voltage (I–V) characteristics. In order to explain the electrical characteristics of metal–polymer–semiconductor (MPS) with a PMMA interface, the investigation of interface states density and series resistance from C–V and G–V characteristics in the MPS structures with thin interfacial insulator layer have been reported. The measurements of capacitance (C) and conductance (G) were found to be strongly dependent on bias voltage and frequency for Al/PMMA/p-Si structures. The values of interface state density (D _it) were calculated. These values of D _it and series resistance (R _s) were responsible for the non-ideal behavior of I–V and C–V characteristics.     

Ant Optimized Link Quality for Ad Hoc on Demand Distance Vector

The wireless interfaces in Mobile Ad-Hoc Networks (MANETs) have limited transmission range and traffic is relayed through intermediate nodes to ensure intra node communication. Routing plays an important role in network reliability and performance. MANET’s characteristics like mobility and resource constraints adversely affect routing performance. A new MANET routing method based on Ad hoc On- demand Distance Vector (AODV) and Ant Colony Optimization is proposed in this paper. Ad hoc networks can emulate achievement of complex solutions with limited intelligence and individual capacity as seen in ant communities. A new link quality metric enhances AODV routing algorithm to enable it to handle link quality to evaluate routes between nodes.     

Simulation of Terahertz Generation from Lateral Diffusion Currents in Semiconductor Devices

In this paper we model the carrier dynamics and resulting THz emission from lateral diffusion currents within a semiconductor device which has been partially masked by a metallic mask. We present a numerical 1D model and a 1D Monte Carlo simulation which both demonstrate that regardless of the excitation laser spot shape we do not expect to see measurable THz emission in the direction of the optical pump propagation from lateral diffusion currents. Experimentally such devices do produce strong THz emission. We analytically investigate the role of the metal mask and we found that it suppresses the emission of dipoles that are in a region that is less than a wavelength away from the interface. The results from the numerical model are also included in a finite element analysis model of the geometry which predicts THz emission if and only if the metal mask is present.     

p +-Si/nano-SiO2/n +-Si capacitor-based tunnel diode with negative differential resistance and a quartz resonator

To demonstrate the extending functionality of the simplest MOS (metal-oxide-semiconductor) capacitor, a structure with a p ⁺-Si/nano-SiO₂ heterojunction in which strongly degenerate n ⁺-Si is used instead of a metal electrode is considered. As a result, a tunnel diode with negative differential resistance and a quartz resonator is obtained. Its electrical characteristics are superior to those of the corresponding Esaki diode and are controlled not only by the Silicon doping level, but also by the SiO₂ thickness.     

Channel Estimation in Long Term Evolution Uplink Using Minimum Mean Square Error-Support Vector Regression

In this paper, minimum mean square error-support vector regression (MMSE-SVR) is proposed, which is shown to be adequate for the estimation of the long term evolution (LTE) uplink channel with nonlinear features. MMSE-SVR was applied to estimate real channel environments such as the vehicular A channels defined by the International Telecommunication Union (ITU). The simulation results show that the proposed method has a better performance than the least squares support vector machine (LS-SVM) and the standard MMSE with linear and spline interpolation.     

System study on direct sequence spectrum of radio-frequency identification

This paper considers points of secure and anti-collision of the Radio-frequency identification (RFID) technology. Source symbols are represented by a special coding, termed Minimum Energy (ME) coding, which exploits redundant bits for saving power when transmitted via RF links with On-Off Keying (OOK). This ME coding is applied to Direct Sequence Spread Spectrum (DSSS) RFID tag in order to enhance security as well as to reduce collision. This synchronized DSSS RFID system is designed and simulation is conducted to verify the advantage of DSSS RFID and present the power efficiency enhance 4 dB, quantities are taken at Bit Error Rate (BER) of 10e-4. When the channel uses the ME coding combined with a DSSS code and OOK without FM0 encoding as is disclosed in the EPC-C1G2/ISO 18000-6 Type C standard. Finally, the maximum number of users in this Direct-Sequence Code Division Multiple Access (DS-CDMA) RFID system is calculated under the condition of successfully acquired.     

Specific features of the hydride vapor-phase epitaxy of nitride materials on a silicon substrate

Specific features of the growth of the GaN/AlN/Si heterocomposite in which layers of Group-III element nitrides are grown on a silicon substrate by hydride vapor-phase epitaxy are studied. The effect of the temperature at which the AlN buffer layer is grown on diffusion processes at the heterointerfaces and on the quality of the epitaxial layers being grown is considered. It is shown that, with the epitaxial technique used, the buffer layer should be grown at high temperatures (1080°C) because the thickness of the component-mixing region is minimized in this case and abrupt interfaces are formed in the GaN/AlN/Si heterocomposite. The double-stage growth of gallium nitride on the high-temperature AlN buffer layer with a thickness of 300–400 nm makes it possible to obtain GaN layers with thicknesses of up to 0.3 μm without crack formation.     

Robust MMSE Design With Asynchronous Interference Mitigation in Cooperative Base Station Systems

This paper investigates minimum mean square error (MMSE) with asynchronous interference mitigation in cooperative base station systems. We consider the asynchronous transmission because of the different propagation times between the base station (BS) and mobile stations (BSs). Meanwhile, the channel quantization errors duo to channel quantization is taken into account in our analysis. The proposed scheme is robust to asynchronous interference and channel quantization errors in BSs cooperation systems. Simulations results show that proposed MMSE scheme achieve an improved performance compared with the conventional MMSE in BSs cooperative systems.     

Check out the Rules: Towards Time-Efficient Rule Checking over RFID Tags

With the rapid proliferation of RFID technologies, RFID has been introduced to the applications like safety inspection and warehouse management. Conventionally a number of deployment rules are specified for these applications. This paper studies a practically important problem of rule checking over RFID tags, i.e., checking whether the specified rules are satisfied according to the RFID tags within the monitoring area. This rule checking function may need to be executed frequently over a large number of tags and therefore should be made efficient in terms of execution time. Aiming to achieve time efficiency, we respectively propose two protocols, CRCP and ECRCP. CRCP works based on collision detection, while ECRCP combines the collision detection and the logical features of the rules. Simulation results indicate that our protocols achieve much better performance than other solutions in terms of time efficiency.     

Mixing properties of mim diodes in the infrared

Point contact MIM diodes of different materials have been tested as harmonic mixers at 29 THz and 88 THz. From the analysis of the I-V static characteristic quantitative informations have been obtained about the effectiveness of the diodes as high order mixers.     

Sixtieth order harmonic mixing to 4.25 THz using a Schottky diode

Harmonic mixing of mm-waves with radiation of 3.7 THz with different Schottky diodes is reported. The highest mixing order is 60 producing a beat between 72 GHz and 4.25 THz radiation. Such high frequency mixing has so far only been possible using cryogenic Josephson mixers. The present result permits substantial simplification of measurements of optical frequencies.     

A Low-Cost RFID Authentication Protocol Against Desynchronization with a Random Tuple

Radio frequency identification (RFID) technology will become one of the most popular technologies to identify objects in the near future. However, the major barrier that the RFID system is facing presently is the security and privacy issue. Recently, a lightweight anti-desynchronization RFID authentication protocol has been proposed to provide security and prevent all possible malicious attacks. However, it is discovered that a type of desynchronization attacks can successfully break the proposed scheme. To overcome the vulnerability under the desynchronization attacks, we propose a low-cost RFID authentication protocol which integrates the operation of the XOR, build-in CRC-16 function, permutation, a random tuple and secret key backup technology to improve the security functionality without increasing any cost than the utralightweight protocols. The analysis shows that our proposal has a strong ability to prevent existing malicious attacks, especially the desynchronization attacks.