An Improved Full Rate Full Diversity QOSTBC with Linear Decoding in MIMO Systems

In this letter, we propose an improved Quasi-orthogonal space-time block code (QOSTBC) with full rate, full diversity, linear decoding and better peak-to-average power ratio (PAPR). Constellation rotation is used to the input symbol vector to ensure full diversity, and then the information symbol vector is interleaved in coordinates and pre-grouped by using a Given rotation matrix. The performance is evaluated by numerical experiments. The PAPR of our proposed QOSTBC is lower than that of CI-QOSTBC in Khan and Rajan (IEEE Trans Inf Theory 52(5):2062–2091, 2006). Meanwhile, the Bit-error-rate versus Signal-to-noise-ratio of our proposed QOSTBC is better than those of OSTBC (Tarokh et al. in IEEE Trans Inf Theory 45(5):1456–1467, 1999) QOSTBC (Jafarkhani in IEEE Trans Wirel Commun 49(1):1–4, 2001), G-QOSTBC (Park et al. in IEEE Commun Lett 12(12):868–870, 2008), slightly better that of the CI-QOSTBC, and as same as that of the recently proposed Minimum Decoding Complexity QOSTBCs (MDC-QOSTBC) in Yuen et al.(IEEE Trans Wirel Commun 4(5):2089–2098, 2005), Wang and Xia (IEEE Trans Inf Theory 55(3):1104–1130, 2009). Compared with MDC-QOSTBC, the proposed QOSTBC has simpler code construct and lower decoding complexity.     

Reanalyzing the basic bandgap reference voltage circuit considering thermal dependence of bandgap energy

The basic bandgap reference voltage generator, BGR, is thoroughly analyzed and relations are reconstructed considering dependency of bandgap energy, E_g, to absolute temperature. The previous works all consider E_g as a constant, independent of temperature variations. However, E_g varies around 25 meV when the temperature is increased from 2 to 92 °C. In this paper the dependence of E_g to absolute temperature, based on HSPICE mosfet models in HSPICE MOSFET Models Manual (Version X-2005.09, 2005), is approximated by a third-order polynomial using Lagrangian interpolating method within the temperature range of 2–92 °C. Accurate analysis on the simplified polynomial reveals that the TC of V_BE must be corrected to ?1.72 mV/°K at 27 °C which has been formerly reported about ?1.5 mV/°K in Razavi (Design of analog CMOS integrated circuits, 2001) and Colombo et al. (Impact of noise on trim circuits for bandgap voltage references, 2007), ?2 mV/°K in Gray et al. (Analysis and design of analog integrated circuits, 2001), Leung and Mok (A sub-1-V 15-ppm/°C CMOS bandgap voltage reference without requiring low threshold voltage device, 2002), Banba et al. (A CMOS bandgap reference circuit with sub-1-V operation, 1999), and ?2.2 mV/°K in Jones and Martin (Analog integrated circuit design, 1997), Tham and Nagaraj (A low supply voltage high PSRR voltage reference in CMOS process, 1995). Another important conclusion is that the typical weighting coefficient of TC+ and TC? terms is modified to about 19.84 at 27 °C temperature from otherwise 16.76, when E_g is considered constant, and also 17.2, in widely read literatures, (Razavi in Design of analog CMOS integrated circuits, 2001). Neglecting the temperature dependence of E_g might introduce a relative error of about 20.5 % in TC of V_BE. Also, resistance and transistor size ratios, which denote the weighting coefficient of TC+ term, might be encountered to utmost 20.3 % error when the temperature dependence of E_g is ignored.     

Formal Verification of Analog and Mixed Signal Designs Using SPICE Circuit Simulation Traces

Analog and Mixed Signal (AMS) designs can be formally modeled as hybrid systems [45] and therefore formal verification techniques applicable to hybrid systems can be deployed to verify them. An extension to a formal verification approach applicable to hybrid systems is proposed to verify AMS designs [31]. In this approach formal verification (FV) is carried out on an AMS block using simulation traces from SPICE, a simulator widely used in the design and verification of analog and AMS blocks. A broader implication of this approach is the ability to carry out hierarchical verification using relevant simulation traces obtained at different abstraction levels of a design when modeled in appropriate platforms. This enables a seamless transition of design and verification artifacts from the highest level of abstraction to the lowest level of implementation at the transistor level of any AMS design and a resulting increase in confidence on the correctness of the final implementation. The proposed approach has been justified with its applications to different AMS design blocks. For each design, its formal model and the proposed computational techniques have been incorporated into CheckMate [11] - a FV tool for hybrid systems based on MATLAB and the Simulink/Stateflow framework from MathWorks. A further justification of the proposed approach is the resulting improvements observed in terms of reduced verification time for different specifications in each design.     

Enhancements of Trapdoor Permutations

We take a closer look at several enhancements of the notion of trapdoor permutations. Specifically, we consider the notions of enhanced trapdoor permutation (Goldreich, Foundation of Cryptography: Basic Applications, 2004) and doubly enhanced trapdoor permutation (Goldreich, Computational Complexity: A Conceptual Perspective, 2011) as well as intermediate notions (Rothblum, A Taxonomy of Enhanced Trapdoor Permutations, 2010). These enhancements arose in the study of Oblivious Transfer and NIZK, but they address natural concerns that may arise also in other applications of trapdoor permutations. We clarify why these enhancements are needed in such applications, and show that they actually suffice for these needs.     

A Note on Constant-Round Zero-Knowledge Proofs of Knowledge

In this note, we show the existence of constant-round computational zero-knowledge proofs of knowledge for all $\mathcal {NP}$ . The existence of constant-round zero-knowledge proofs was proven by Goldreich and Kahan (Journal of Cryptology, 1996), and the existence of constant-round zero-knowledge arguments of knowledge was proven by Feige and Shamir (CRYPTO, 1989). However, the existence of constant-round zero-knowledge proofs of knowledge for all $\mathcal {NP}$ is folklore, to the best of our knowledge, since no proof of this fact has been published.     

Concurrent Zero Knowledge, Revisited

We provide a more general and, in our eyes, simpler variant of Prabhakaran, Rosen and Sahai’s (FOCS ’02, pp. 366–375, 2002) analysis of the concurrent zero-knowledge simulation technique of Kilian and Petrank (STOC ’01, pp. 560–569, 2001).     

Securely Obfuscating Re-Encryption

We present a positive obfuscation result for a traditional cryptographic functionality. This positive result stands in contrast to well-known impossibility results (Barak et al. in Advances in Cryptology??CRYPTO??01, 2002), for general obfuscation and recent impossibility and implausibility (Goldwasser and Kalai in 46th IEEE Symposium on Foundations of Computer Science (FOCS), pp.?553?C562, 2005) results for obfuscation of many cryptographic functionalities. Whereas other positive obfuscation results in the standard model apply to very simple point functions (Canetti in Advances in Cryptology??CRYPTO??97, 1997; Wee in 37th ACM Symposium on Theory of Computing (STOC), pp.?523?C532, 2005), our obfuscation result applies to the significantly more complex and widely-used re-encryption functionality. This functionality takes a ciphertext for message m encrypted under Alice??s public key and transforms it into a ciphertext for the same message m under Bob??s public key. To overcome impossibility results and to make our results meaningful for cryptographic functionalities, our scheme satisfies a definition of obfuscation which incorporates more security-aware provisions.     

A hybrid multiagent routing approach for wireless ad hoc networks

Wireless ad-hoc networks are infrastructureless networks that comprise wireless mobile nodes able to communicate each other outside wireless transmission range. Due to frequent network topology changes in one hand and the limited underlying bandwidth in the other hand, routing becomes a challenging task. In this paper we present a novel routing algorithm devoted for mobile ad hoc networks. It entails both reactive and proactive components. More precisely, the algorithm is based on ant general behavior, but differs from the classic ant methods inspired from Ant-Colony-Optimization algorithm [1]. We do not use, during the reactive phase, a broadcasting technique that exponentially increases the routing overhead, but we introduce a new reactive route discovery technique that considerably reduces the communication overhead. In the simulation results, we show that our protocol can outperform both Ad hoc On-demand Distance Vector (AODV) protocol [2], one of the most important current state-of-the-art algorithms, and AntHocNet protocol [5], one of the most important ant-based routing algorithms, in terms of end-to-end delay, packet delivery ratio and the communication overhead.     

Palm-Dorsal Vein Recognition Method Based on Histogram of Local Gabor Phase XOR Pattern with Second Identification

This paper proposes a palm-dorsal vein recognition method with local Gabor phase features, which includes a second identification for more accuracy. First, we extract quadrant-bit codes from the 2D Gabor transformation of a vein image. Then using the Histogram of the Local Gabor Phase XOR Pattern (HLGPXP) obtains the vein texture features, which combines the global information and the local information. Finally, the chi-square distance is adopted for recognition. Using the texture features based on the local Gabor codes above, the Second Identification (SI) segments the vein images and regards the non-overlap degree between images as a matching criterion. The experimental results show the Error Equation Rate (EER) of our method (HLGPXP-SI) decreases by 11.7 %, 4.8 % respectively than Modified Local Binary Pattern (MLBP) [1], Local Gabor Binary Pattern (LGBP) [2] on Database A (204 high-quality palm-dorsal vein images from 68 hands), and on Database B (400 low-quality palm-dorsal vein images from 100 hands), it decreases by 18.94 %, 15.51 % respectively than Selected Gabor Phase and Amplitude Features (SGPAF) [3], Direct Gabor Phase Coding (DGPC) [4].     

Positive L_1 Observer Design for Positive Switched Systems

This paper investigates the problem of \(L_1\) observer design for positive switched systems. Firstly, a new kind of positive \(L_1\) observer is proposed for positive switched linear delay-free systems with observable and unobservable subsystems. Based on the average dwell time approach, a sufficient condition is proposed to ensure the existence of the positive \(L_1\) observer. Under the condition obtained, the estimated error converges to zero exponentially, and the \(L_1\) -gain from the disturbance input to the estimated error is less than a prescribed level. Then the proposed design result is extended to positive switched systems with mixed time-varying delays, where the mixed time-varying delays are presented in the form of discrete delay and distributed delay. Finally, two numerical examples are given to demonstrate the feasibility of the obtained results.     

Improved Cryptanalysis of AES-like Permutations

AES-based functions have attracted of a lot of analysis in the recent years, mainly due to the SHA-3 hash function competition. In particular, the rebound attack allowed to break several proposals and many improvements/variants of this method have been published. Yet, it remained an open question whether it was possible to reach one more round with this type of technique compared to the state-of-the-art. In this article, we close this open problem by providing a further improvement over the original rebound attack and its variants, that allows the attacker to control one more round in the middle of a differential path for an AES-like permutation. Our algorithm is based on lists merging as defined in (Naya-Plasencia in Advances in Cryptology: CRYPTO 2011, pp. 188–205, 2011) and we generalized the concept to non-full active truncated differential paths (Sasaki et al. in Lecture Notes in Computer Science, pp. 38–55, 2010). As an illustration, we applied our method to the internal permutations used in Grøstl, one of the five finalist hash functions of the SHA-3 competition. When entering this final phase, the designers tweaked the function so as to thwart attacks from Peyrin (Peyrin in Lecture Notes in Computer Science, pp. 370–392, 2010) that exploited relations between the internal permutations. Until our results, no analysis was published on Grøstl and the best results reached 8 and 7 rounds for the 256-bit and 512-bit versions, respectively. By applying our algorithm, we present new internal permutation distinguishers on 9 and 10 rounds, respectively.     

High-resolution estimation of the directions-of-arrival distribution by algebraic phase unwrapping algorithms

We present nontrivial utilization methods of a pair of symbolic algebraic algorithms (Yamada et?al. in IEEE Trans Signal Process 46:1639?C1664, 1998; Yamada and Bose in IEEE Trans Circuits Syst 1 Fundam Theory Appl 49:298?C304, 2002) which were developed originally for multidimensional phase unwrapping and zero-distribution problems. Given the minor subspace of the covariance matrix of the data measured at a uniform linear array of sensors, the proposed methods provide estimates of the Directions-of-Arrival (DOA) distribution of multiple narrowband signals, i.e., the number of DOA in an arbitrarily specified range, without using any numerical search for each direction of arrival. The proposed methods can serve as powerful mathematical tools to extract global information in the high-resolution DOA estimation problems.     

Image distortion analysis based on normalized perceptual information distance

Image distortion analysis is a fundamental issue in many image processing problems, including compression, restoration, recognition, classification, and retrieval. Traditional image distortion evaluation approaches tend to be heuristic and are often limited to specific application environment. In this work, we investigate the problem of image distortion measurement based on the theory of Kolmogorov complexity, which has rarely been studied in the context of image processing. This work is motivated by the normalized information distance (NID) measure that has been shown to be a valid and universal distance metric applicable to similarity measurement of any two objects (Li et al. in IEEE Trans Inf Theory 50:3250–3264, 2004). Similar to Kolmogorov complexity, NID is non-computable. A useful practical solution is to approximate it using normalized compression distance (NCD) (Li et al. in IEEE Trans Inf Theory 50:3250–3264, 2004), which has led to impressive results in many applications such as construction of phylogeny trees using DNA sequences (Li et al. in IEEE Trans Inf Theory 50:3250–3264, 2004). In our earlier work, we showed that direct use of NCD on image processing problems is difficult and proposed a normalized conditional compression distance (NCCD) measure (Nikvand and Wang, 2010), which has significantly wider applicability than existing image similarity/distortion measures. To assess the distortions between two images, we first transform them into the wavelet transform domain. Assuming stationarity and good decorrelation of wavelet coefficients beyond local regions and across wavelet subbands, the Kolmogorov complexity may be approximated using Shannon entropy (Cover et al. in Elements of information theory. Wiley-Interscience, New York, 1991). Inspired by Sheikh and Bovik (IEEE Trans Image Process 15(2):430–444, 2006), we adopt a Gaussian scale mixture model for clusters of neighboring wavelet coefficients and a Gaussian channel model for the noise distortions in the human visual system. Combining these assumptions with the NID framework, we derive a novel normalized perceptual information distance measure, where maximal likelihood estimation and least square regression are employed for parameter fitting. We validate the proposed distortion measure using three large-scale, publicly available, and subject-rated image databases, which include a wide range of practical image distortion types and levels. Our results demonstrate the good prediction power of the proposed method for perceptual image distortions.     

A new class of multi-dimensional Teager-Kaiser and higher order operators based on directional derivatives

This work aims at introducing some energy operators linked to Teager-Kaiser energy operator (TKEO) (Kaiser in On a simple algorithm to calculate the energy of a signal, pp 381–384, 1990), its associated higher order versions and expanding them to multi-dimensional signals. These operators are very useful for analysing oscillatory signals with time-varying amplitude and frequency (AM–FM). We first propose a new mathematical expression of these operators using directional derivatives along any n-D vector and Kronecker powers (Proposition 1, Sect. 3). This mathematical formulation allows us to extend to n-D case some properties of the classical TKEO such as tracking of AM envelope and instantaneous frequency of a multi-dimensional AM–FM signal. In addition, we have introduced a new scalar function using the directional derivative along a vector to recover the “sign” of the frequency components. Applications of this model to a local n-D AM–FM signal and the related demodulation errors are presented. To show the effectiveness and the robustness of the new class of operators in term of envelope and frequency tracking, results obtained on synthetic and real data are compared to multi-dimensional energy separation algorithm (Maragos and Bovik in J Opt Soc Am A 12:1867–1876, 1995) and to our previously developed method (Salzenstein and Boudraa in Signal Process 89(4):623–640, 2009). Finally, the performances of these methods are investigated in the presence of an additive noise.     

Performances of chaos-coded modulation concatenated with Alamouti’s space–time block code

Recently, some works have shown that it was possible to obtain quite good bit error rate performances over an additive white Gaussian noise channels with chaotic systems. In this research field, this paper proposes new insights for the chaos-coded modulation (CCM) schemes originally proposed by Kozic et al. (2003; IEEE Trans Circuits Syst Regul Pap 53:2048–2059, 2006). A detailed study of the distance spectrum of such schemes is proposed and an approximation of its distribution by means of Gaussian or Rayleigh mixtures is given. Furthermore, using these approximate distributions, a complete study of the performances of these CCM schemes when they are concatenated with a space–time block code is proposed. Accurate bounds are obtained even in the case of time-selective channels.     

A novel fuzzy system for edge detection in noisy image using bacterial foraging

Bio-inspired edge detection using fuzzy logic has achieved great attention in the recent years. The bacterial foraging (BF) algorithm, introduced in Passino (IEEE Control Syst Mag 22(3):52–67, 2002) is one of the powerful bio-inspired optimization algorithms. It attempts to imitate a single bacterium or groups of E. Coli bacteria. In BF algorithm, a set of bacteria forages towards a nutrient rich medium to get more nutrients. A new edge detection technique is proposed to deal with the noisy image using fuzzy derivative and bacterial foraging algorithm. The bacteria detect edge pixels as well as noisy pixels in its path during the foraging. The new fuzzy inference rules are devised and the direction of movement of each bacterium is found using these rules. During the foraging if a bacterium encounters a noisy pixel, it first removes the noisy pixel using an adaptive fuzzy switching median filter in Toh and Isa (IEEE Signal Process Lett 17(3):281–284, 2010). If the bacterium does not encounter any noisy pixel then it searches only the edge pixel in the image and draws the edge map. This approach can detect the edges in an image in the presence of impulse noise up to 30%.     

Self-Calibration of Output Match and Reverse Isolation in LNAs Based Switchable Resistor

With recent advances in CMOS process technology, the concept of system-on-a-chip (SoC) has been realized by integrating more and more digital and analog building blocks in a single chip [2, 9]. Additionally, these advances have brought several new types of processes faults (soft fault) and higher process variations to RF circuit resulting performances degradation. In order to compensate the RF circuit performance, a novel efficient self-calibration method for 865?C870?MHz low noise amplifiers (LNAs), which constitute a RF mixed-signal circuit, is developed. This technique detects any deviation from the output match and from reverse isolation using built-in self test (BIST) methods, and then provides a corrective measure to recalibrate these LNA performances to the possible optimal value. This proposed self-calibration technique uses a switchable resistor which has been designed to investigate its ability to compensate for output match S22 and reverse isolation S12 without affecting other LNA performances. The use of this method saves space on chip and prevents adding switch resistor noise. In addition, the new calibration design shows the ability to calibrate S22 and S12 due to the catastrophic fault.     

Logic Minimization Techniques with Applications to Cryptology

A new technique for combinational logic optimization is described. The technique is a two-step process. In the first step, the nonlinearity of a circuit—as measured by the number of nonlinear gates it contains—is reduced. The second step reduces the number of gates in the linear components of the already reduced circuit. The technique can be applied to arbitrary combinational logic problems, and often yields improvements even after optimization by standard methods has been performed. In this paper we show the results of our technique when applied to the S-box of the Advanced Encryption Standard (FIPS in Advanced Encryption Standard (AES), National Institute of Standards and Technology, 2001). We also show that, in the second step, one is faced with an NP-hard problem, the Shortest Linear Program (SLP) problem, which is to minimize the number of linear operations necessary to compute a set of linear forms. In addition to showing that SLP is NP-hard, we show that a special case of the corresponding decision problem is Max SNP-complete, implying limits to its approximability. Previous algorithms for minimizing the number of gates in linear components produced cancellation-free straight-line programs, i.e., programs in which there is no cancellation of variables in GF(2). We show that such algorithms have approximation ratios of at least 3/2 and therefore cannot be expected to yield optimal solutions to nontrivial inputs. The straight-line programs produced by our techniques are not always cancellation-free. We have experimentally verified that, for randomly chosen linear transformations, they are significantly smaller than the circuits produced by previous algorithms.