Cyclotomic Linear Codes of Order $3$

In this correspondence, two classes of cyclotomic linear codes over GF(q) of order 3 are constructed and their weight distributions are determined. The two classes are two-weight codes and contain optimal codes. They are not equivalent to irreducible cyclic codes in general when q > 2.     

一种(41, 21, 9)平方剩余码的快速代数译码算法

为了降低译码时的计算复杂度以及减少译码时间,该文通过对牛顿恒等式进行推导得到了(41, 21, 9) QR码不需要计算未知校验子就可求得错误位置多项式系数的代数译码算法,同时也针对改善部分客观地给出了计算复杂度的理论分析。此外,为了进一步降低译码时间,提出判定接收码字中出现不同错误个数的更简化的判断条件。仿真结果表明该文提出算法在不降低Lin算法所达到的译码性能的前提下,降低了译码时间。     

Decoding the (47,24,11) Quadratic Residue Code Using Bit-Error Probability Estimates

A new algorithm is developed to facilitate faster decoding of the (47,24,11) quadratic residue (QR) code. This decoder, based on the idea first developed by Reed in a 1959 MIT Lincoln Laboratory Report, uses real channel data to estimate the individual bit-error probabilities in a received word. The algorithm then sequentially inverts the bits with the highest probability of error until one of the errors is canceled. The remaining errors are then corrected by the use of algebraic decoding techniques. This new algorithm, called the reliability-search algorithm, is a complete decoder that significantly reduces the decoding complexity in terms of CPU time while maintaining the same bit-error rate (BER) performance. In fact, this algorithm is an appropriate modification to the algorithm developed by Chase.     

Results of the Enumeration of Costas Arrays of Order $27$

This correspondence presents the results of the enumeration of Costas arrays of order $27$: all arrays found, except for one, are accounted for by the Golomb and Welch construction methods.      

Opening of Hybrid Bandgaps in Two-Dimensional Photonic Crystals of Pb(Mg$_{1/3}$Nb$_{1/3}$ )O$_{3}$–PbTiO $_{3}$ Having Very Low Refractive Index Contrast

The effect of anisotropy on two-dimensional photonic crystals of hexagonally arranged Pb(Mg_1/3Nb_1/3)O₃-PbTiO₃ (PMNT) rods in air background was analyzed using a finite-difference time-domain method. The refractive index contrast between PMNT (n = 2.47) and air is low compared to conventional semiconductor-air photonic crystals. Yet, hybrid (polarization-independent) photonic bandgaps were achieved for anisotropic PMNT rods by adjusting the structural parameters and the anisotropy. The maximum bandwidth found was 20 nm. It was possible to engineer the center wavelength of this bandgap to 980, 1300, and 1550 nm, for potential applications as switches, electrooptic filters, and modulators in this region.     

Eigendecomposition of Images Correlated on $S^{1}$, $S^{2}$, and $SO(3)$ Using Spectral Theory

Eigendecomposition represents one computationally efficient approach for dealing with object detection and pose estimation, as well as other vision-based problems, and has been applied to sets of correlated images for this purpose. The major drawback in using eigendecomposition is the off line computational expense incurred by computing the desired subspace. This off line expense increases drastically as the number of correlated images becomes large (which is the case when doing fully general 3-D pose estimation). Previous work has shown that for data correlated on S ¹ , Fourier analysis can help reduce the computational burden of this off line expense. This paper presents a method for extending this technique to data correlated on S ² as well as SO(3) by sampling the sphere appropriately. An algorithm is then developed for reducing the off line computational burden associated with computing the eigenspace by exploiting the spectral information of this spherical data set using spherical harmonics and Wigner-D functions. Experimental results are presented to compare the proposed algorithm to the true eigendecomposition, as well as assess the computational savings.     

Linear Corrector Overcoming Minimum Distance Limitation for Secure TRNG from (17, 9, 5) Quadratic Residue Code

A true random number generator (TRNG) is widely used to generate secure random numbers for encryption, digital signatures, authentication, and so on in crypto‐systems. Since TRNG is vulnerable to environmental changes, a deterministic function is normally used to reduce bias and improve the statistical properties of the TRNG output. In this paper, we propose a linear corrector for secure TRNG. The performance of a linear corrector is bounded by the minimum distance of the corresponding linear error correcting code. However, we show that it is possible to construct a linear corrector overcoming the minimum distance limitation. The proposed linear corrector shows better performance in terms of removing bias in that it can enlarge the acceptable bias range of the raw TRNG output. Moreover, it is possible to efficiently implement this linear corrector using only XOR gates, which must have a suitable hardware size for embedded security systems.     

Reducing the Number of Comparators in Multibt $Delta Sigma $ Modulators

Multibit feedback, being one way of lowering DeltaSigma modulators power consumption, has a major obstacle: the number of components in the internal analog-to-digital converter (ADC) and digital-to-analog converter (DAC). Nevertheless, the number of comparators in the ADC can be significantly reduced depending on the order of noise-shaping and the oversampling ratio. In this paper, we propose an auto-ranging algorithm with a mechanism to keep the structure stable that emulates more quantization levels than that allowed by the number of comparators. As the recourse to segmented DACs allows lowering the complexity of the mismatch shaping encoder, the auto-ranging ADC brings the benefits of multibit feedback without the usual increase in size and power consumption. The internal number of bits in DeltaSigma modulators is no more restricted by the difficulty of building the flash ADC with a low voltage supply.     

Blind Deconvolution of DS-CDMA Signals by Means of Decomposition in Rank-$(1,L,L)$ Terms

In this paper, we present a powerful technique for the blind extraction of direct-sequence code-division multiple access (DS-CDMA) signals from convolutive mixtures received by an antenna array. The technique is based on a generalization of the canonical or parallel factor decomposition (CANDECOMP/PARAFAC) in multilinear algebra. We present a bound on the number of users under which blind separation and deconvolution is guaranteed. The solution is computed by means of an alternating least squares (ALS) algorithm. The excellent performance is illustrated by means of a number of simulations. We include an explicit expression of the Cramer-Rao bound (CRB) of the transmitted symbols.     

The Correlation Distribution of Quaternary Sequences of Period $2(2^n-1)$

Family A is a family of sequences of period 2ⁿ - 1 over Zi, the ring of integers modulo 4. This family has optimal correlation properties and its correlation distribution is well known. Two related families of quaternary sequences are the families B and C. These are families of sequences over Z₄ of period 2(2ⁿ - 1). In recent years, new families of quaternary sequences of period 2(2ⁿ - 1) have been constructed by modifying the sequence families B and C in a nonlinear way. This has resulted in a new family D of sequences of period 2(2ⁿ - 1) which has optimal correlation properties, but until now the correlation distribution of this family has not been known. In this paper, we completely determine the correlation distribution of family D by making use of properties of exponential sums.     

Stochastic Modeling of the Transform-Domain $varepsilon {rm LMS}$ Algorithm

This paper presents a statistical analysis of the transform-domain least-mean-square (TDLMS) algorithm, resulting in a more accurate model than those discussed in the current open literature. The motivation to analyze such an algorithm comes from the fact that the TDLMS presents a higher convergence speed for correlated input signals, as compared with other adaptive algorithms possessing a similar computational complexity. Such a fact makes it a highly competitive alternative to some applications. Approximate analytical models for the first and second moments of the filter weight vector are obtained. The TDLMS algorithm has an orthonormal transformation stage, accomplishing a decomposition of the input signal into distinct frequency bands, in which the interband samples are practically uncorrelated. On the other hand, the intraband samples are correlated; the larger the number of bands, the higher their correlation. The model is then derived taking into account such a correlation, requiring that a high-order hyperelliptic integral be computed. In addition to the proposed model, an approximate procedure for computing high-order hyperelliptic integrals is presented. A regularization parameter is also considered in the model expressions, permitting to assess its impact on the adaptive algorithm behavior. An upper bound for the step-size control parameter is also obtained. Through simulation results, the accuracy of the proposed model is assessed.     

A Comparative NBTI Study of $hbox{HfO}_{2}$, $hbox{HfSiO}_{x}$, and SiON p-MOSFETs Using UF-OTF $I_{rm DLIN}$ Technique

The time, temperature, and oxide-field dependence of negative-bias temperature instability is studied in $hbox{HfO}_{2}/hbox{TiN}$, $ hbox{HfSiO}_{x}/hbox{TiN}$, and SiON/poly-Si p-MOSFETs using ultrafast on-the-fly $I_{rm DLIN}$ technique capable of providing measured degradation from very short (approximately microseconds) to long stress time. Similar to rapid thermal nitrided oxide (RTNO) SiON, $hbox{HfO}_{2}$ devices show very high temperature-independent degradation at short (submilliseconds) stress time, not observed for plasma nitrided oxide (PNO) SiON and $hbox{HfSiO}_{x}$ devices. $hbox{HfSiO}_{x}$ shows lower overall degradation, higher long-time power-law exponent, field acceleration, and temperature activation as compared to $hbox{HfO}_{2}$, which are similar to the differences between PNO and RTNO SiON devices, respectively. The difference between $ hbox{HfSiO}_{x}$ and $hbox{HfO}_{2}$ can be attributed to differences in N density in the $hbox{SiO}_{2}$ IL of these devices.      

Characterization of $m$-Sequences of Lengths $2^{2k}-1$ and $2^{k}-1$ With Three-Valued Cross Correlation

Considered is the distribution of the cross correlation between in-sequences of length 2^2k -1, where m = 2k, and m-sequences of shorter length 2^k -1. New pairs of m -sequences with three-valued cross correlation are found and the complete correlation distribution is determined. Finally, we conjecture that there are no more cases with a three-valued cross correlation apart from the ones proven here.     

Radix-3$,times,$3 Algorithm for The 2-D Discrete Hartley Transform

In this correspondence, we propose a vector-radix algorithm for the fast computation of a 2-D discrete Hartley transform (DHT). For data sequences whose length is a power of three, a radix-3 times 3 decimation in frequency algorithm is developed. It decomposes a length-N times N DHT into nine length-(N/3) times N (N/3) DHTs. Comparison of the computational complexity with known algorithms shows that the proposed algorithm, in some cases, reduces significantly the number of arithmetic operations.     

A 3$,times,$5-Gb/s Multilane Low-Power 0.18-$mu{hbox {m}}$ CMOS Pseudorandom Bit Sequence Generator

A low-power, three-lane, pseudorandom bit sequence (PRBS) generator has been fabricated in a 0.18-mum CMOS process to test a multilane multi-Gb/s transmitter that cancels far-end crosstalk. Although the proposed PRBS generator was designed to produce three uncorrelated 12-Gb/s PRBS sequences, measurement results included in this paper have been obtained at only 5 Gb/s due to test setup limitations. The prototype employs a CMOS latch optimized to operate at frequencies close to the of the process and a current-mode logic (CML) MUX with modified active inductor loads for better high-speed large-signal behavior. In order to reduce the power consumption, a quarter-clock rate linear feedback shift register (LFSR) core in a power-efficient parallel architecture has been implemented to minimize the use of power-hungry, high-speed circuitry. Further power reduction has been achieved through the clever partitioning of the system into static logic and CML. In addition, the prototype design produces three uncorrelated 12-Gb/s data streams from a single quarter-rate LFSR core, thereby amortizing the power across multiple channels which lowers the power per channel by 3 times. The total measured power consumption at 5 Gb/s is 131 mW per lane and the calculated figure of merit per lane is 0.84 pJ/bit, which is significantly better than previously published designs.     

Spectroscopy and Diode-Pumped Laser Experiments of LiLuF$_{bf 4}$:Tm$^{{bf 3}+}$ Crystals

In this work we report on the 2-${mbi mu}$m laser emission of LiLuF ${_{bf 4}}$ crystals doped with Thulium trivalent ions (Tm:LLF) at different doping density up to 16%. We will present our results regarding growth, absorption and emission spectroscopy, Judd–Ofelt analysis and room temperature diode pumping laser experiments as a function of the dopant density. The best result is 56% of slope efficiency, with a maximum output power of 280 mW. The emission wavelength ranges between 1985 and 2038 nm, exploiting the vibronic emission of Tm in LLF.      

High-Speed High-Isolation 2$, times ,$2 Fiber-Optic Switch for Wideband Radar Photonic Beamforming Controls

A new high-performance 2$, times ,$2 fiber-optic switch is designed and demonstrated for wideband radar photonic beamforming controls. The switch deploys two bulk acoustooptic deflectors (AODs) in an imaging free-space symmetric optical design that exploits image inversion control via a Dove prism to form a 2$, times ,$2 fully reversible low crosstalk noise high-speed switching structure. Experiments at the 1550-nm test wavelength show the switch to handle 0.5-W level optical input powers, $≪ {hbox{2.2-}}mu$s switching time, $≪ $2.6-dB fiber-to-fiber optical loss, better than 56-dB optical crosstalk levels, and $≪$0.2-dB polarization-dependent loss (PDL).      

High-Resolution Refractive Index and Micro-Raman Spectroscopy of Planar Waveguides in KGd(WO $_{4}$) $_{2}$ Formed by Swift Heavy Ion Irradiation

We report on the characterization of planar waveguides formed in the Raman-active crystal KGd(WO$_{4}$ )$_{2}$ using swift carbon, fluorine, and oxygen ion irradiation. The characterization of the waveguiding regions was performed using high-resolution microreflectivity and micro-Raman spectroscopy. The high-resolution microreflectivity measurement fully characterizes the refractive index profile of the barrier formed by amorphization of the crystal and detects other index variations not detected by the m-line technique. Raman spectroscopy measurements reveal details of the Raman properties of the crystal in the waveguiding region in relation to the rest of the sample for the different ion irradiations. Both of these measurement techniques are shown to be important for use of KGd(WO$_{4}$) $_{2}$ in integrated Raman-active devices.      

A Real-Time and Reliable Transport (RT)$^{2}$ Protocol for Wireless Sensor and Actor Networks

Wireless sensor and actor networks (WSANs) are characterized by the collective effort of heterogeneous nodes called sensors and actors. Sensor nodes collect information about the physical world, while actor nodes take action decisions and perform appropriate actions upon the environment. The collaborative operation of sensors and actors brings significant advantages over traditional sensing, including improved accuracy, larger coverage area and timely actions upon the sensed phenomena. However, to realize these potential gains, there is a need for an efficient transport layer protocol that can address the unique communication challenges introduced by the coexistence of sensors and actors. In this paper, a real-time and reliable transport (RT) protocol is presented for WSANs. The objective of the (RT) protocol is to reliably and collaboratively transport event features from the sensor field to the actor nodes with minimum energy dissipation and to timely react to sensor information with a right action. In this respect, the (RT) protocol simultaneously addresses congestion control and timely event transport reliability objectives in WSANs. To the best of our knowledge, this is the first research effort focusing on real-time and reliable transport protocol for WSANs. Performance evaluations via simulation experiments show that the (RT) protocol achieves high performance in terms of reliable event detection, communication latency and energy consumption in WSANs.     

A 1-V 45-GHz Balanced Amplifier With 21.5-dB Gain Using 0.18-$mu{hbox {m}}$ CMOS Technology

A fully integrated balanced amplifier was realized in a standard 0.18-mum CMOS technology. From the measured-parameters, a gain up to 21.5 dB was achieved at 45.4 GHz under a supply voltage of only 1 V and a total power consumption of 89 mW. An effective technique, i.e., pi-type parallel resonance, was proposed to enhance the device and circuit frequency response. In addition, the semicoaxial line structure was used to reduce the signal loss and physical size of the Lange couplers in the amplifier. To the best of the authors' knowledge, the proposed balanced amplifier demonstrated the highest operation frequency and the lowest operation voltage among the published millimeter-wave amplifiers using a similar technology.