Sharif Digital Repository

Hardware Trojans are one of the serious threats with detrimental, irreparable effects on the functionality, security, and performance of digital integrated circuits. It is difficult to detect Trojans because of their diversity in size and performance. While the majority of current methods focus on Trojan detection during chip testing, run-time techniques can be employed to gain unique advantages. This paper proposes a method based on the online scalable detection technique, which eliminates the need for a reference chip. Involving local detectors, this technique assesses the variations in the logical values of each node to find out whether there are Trojans. This method excludes time and... 

Inserting redundancy to arithmetic codes is a common strategy to add error detection capability to this well-known family of source codes. By using this strategy error correction is possible through some decoding algorithms such as Viterbi decoder. In this paper a system has proposed that uses finite state integer arithmetic codes (FSAC) as a joint source-channel code in combination with a cyclic redundancy check (CRC) and a List Viterbi decoder. The proposed scheme has shown better performance than previous ones. © 2009 IEEE  

This paper presents a novel method for cooperative educational dissemination systems. Taking into consideration the inherent characteristics of distance learning video streams (existence of a few slow moving objects in a classroom), we have proposed a novel content-based video coding method that is very efficient at low bitrate channels. On the encoding side, we have applied a background subtraction algorithm for motion segmentation using a novel statistical background modeling approach. At each frame, the moving objects are extrapolated with a rectangular model and tracked frame by frame (which forms the only data needed to be sent over the channel). On the decoding side, we have used a new... 

Optical tweezers are indispensable instruments for applying and measuring Pico-Newton range forces. The magnitude of the exerted force is determined by measuring the displacement of the trapped bead from the center of the trap. Recently, we developed a new detection system for optical tweezers based on Moiré Deflectometry (MD). In this work, we show, both theoretically and experimentally, that the introduced method can be used for detection in the axial direction, as well, with a significantly larger sensitivity compared to the commonly used QPD method. As an example, for a 2.17μm polystyrene bead this method could provide a sensitivity 285% larger than that of the QPD method. © 2019... 

The increasing rate of transient faults necessitates the use of on-chip fault-tolerant techniques in embedded microprocessors. Performance overhead is a challenging problem in on-chip fault-tolerant techniques used in the random logic of the embedded microprocessors. This paper presents a signature-based error detection and roll-back recovery technique for the control logic with much lower performance overhead as compared to many previous techniques. The low performance overhead is achieved by eliminating the fault masking overhead cycles in the previous techniques. The performance overhead is analytically studied, and the analytical results recommend at which fault rate the use of the... 

In this study, we presented a method for distributing data storage by using residue number system for mobile systems and wireless networks based on peer to peer paradigm. Generally, redundant residue number system is capable in error detection and correction. In proposed method, we made a new system by mixing Redundant Residue Number System (RRNS), Multi Level Residue Number System (ML RNS) and Multiple Valued Logic (MVL RNS) which was perfect for parallel, carry free, high speed arithmetic and the system supports secure data communication. In addition it had ability of error detection and correction. In comparison to other number systems, it had many improvements in data security, error... 

Long Reed-Solomon codes over the prime field GF(216 + 1) are proposed as a low overhead channel code for reliable transmission of video over noisy and lossy channels. The added redundancy is near optimal from the information theoretic point of view contrary to the conventionally used intra-coding and sync (marker) insertion in video transmission that are not justified theoretically. Compared to known source-channel coding methods, we have achieved the quality of the output of source coder by providing nearly error free transmission. (By nearly error free we mean an arbitrarily small error probability.) The price paid for such remarkable video quality improvement and relatively low complexity... 

This paper presents a behavioral-based error detection technique called control flow checking by execution tracing (CFCET) to increase concurrent error detection capabilities of commercial off-the-shelf (COTS) processors. This technique traces the program jumps graph (PJG) at run-time and compares it with the reference jumps graph to detect possible violations caused by transient faults. The reference graph is driven by a preprocessor from the source program. The idea behind the CFCET is based on using an external watchdog processor (WDP) and also the internal execution tracing feature available in COTS processors to monitor the addresses of taken branches in a program, externally. This is... 

The secure hash algorithm (SHA)-3 has been selected in 2012 and will be used to provide security to any application which requires hashing, pseudo-random number generation, and integrity checking. This algorithm has been selected based on various benchmarks such as security, performance, and complexity. In this paper, in order to provide reliable architectures for this algorithm, an efficient concurrent error detection scheme for the selected SHA-3 algorithm, i.e., Keccak, is proposed. To the best of our knowledge, effective countermeasures for potential reliability issues in the hardware implementations of this algorithm have not been presented to date. In proposing the error detection... 

Predictability, energy consumption, area and reliability are the major concerns in embedded systems. Using scratchpad memories (SPMs) instead of cache memories play an increasing role to satisfy these concerns. Both cache and SPM as on-chip SRAM memories are highly vulnerable to soft errors and as they contain the most frequently used blocks of the program, their errors can easily propagate in system leading to erroneous results. Unlike the instruction cache, an error in the instruction SPM cannot be corrected using only parity bits by invalidating the erroneous line. This study suggests a low-cost mechanism to protect the instruction SPM against soft errors. The main idea underlying the... 

Simulation models often include a large number of input factors, many of them may be unimportant to the output; justifying the use of factor screening experiments to eliminate unimportant input factors from consideration in later stages of analysis. With a large number of factors, the challenge is designing experiments so that total number of runs and consequently the required time and cost decrease while achieving a satisfactory detection rate. This article employs frequency domain method (FDM) which is applicable in discrete-event simulation models to propose a new statistic defined as the ratio of estimated signal spectrum to maximum estimated noise spectrum. The proposed method not only... 

Two important objectives in wireless sensor networks are reliability and reducing energy consumption. Hence, overcoming energy constraints and utilizing error control schemes such as Automatic Repeat Request (ARQ) and Forward Error Correction (FEC) are necessary to improve the energy efficiency and reliability. However, these two concerns are at odds, so there is a trade-off between them. Considering this point, the impact of various error control schemes on these objectives and the trade-off between them has been considered in Bluetooth networks recently. However, all these works consider ideal assumptions (e.g., perfect error detection) only. This work evaluates the energy-efficiency of... 

In this paper, a low energy yet reliable communication scheme for network-on-chip is suggested. To reduce the communication energy consumption, we invoke low-swing signals for transmitting data, as well as data encoding techniques, for minimizing both self and coupling switching capacitance activity factors. To maintain the communication reliability of communication at low-voltage swing, an error control coding (ECC) technique is exploited. The decision about end-To-end or hop-To-hop ECC schemes and the proper number of detectable errors are determined through high-level mathematical analysis on the energy and reliability characteristics of the techniques. Based on the analysis, the extended... 

Scratchpad memory (SPM) is widely used in modern embedded processors to overcome the limitations of cache memory. The high vulnerability of SPM to soft errors, however, limits its usage in safety-critical applications. This paper proposes an efficient fault-tolerant scheme, called cache-assisted duplicated SPM (CADS), to protect SPM against soft errors. The main aim of CADS is to utilize cache memory to provide a replica for SPM lines. Using cache memory, CADS is able to guarantee a full duplication of all SPM lines. We also further enhance the proposed scheme by presenting buffered CADS (BCADS) that significantly improves the CADS energy efficiency. BCADS is compared with two well-known... 

This paper presents an optimum pre-filter for ICA based multi-input multi-output OFDM system. In our former work, we presented a pre-filter solution for multiuser reconstruction in ICA based MIMO-OFDM systems [1,2]. Here, based on the structure of the system and former pre-filter solution, an optimization problem has been designed to give us the optimum pre-filter. The designed problem is based on minimization of the estimation error of ambiguities inherent to ICA in reconstruction of the data after separation. The optimization problem is mathematically solved and a set of optimized coefficients are obtained. Among the obtained set as optimum coefficients, optimum coefficients are acquired... 

This paper presents an Optimum pre-filter for ICA based mulit-input multi-output OFDM System. In our former work, we presented a pre-filter solution for multiuser reconstruction in ICA based MIMO-OFDM systems [1], [2]. Here, based on the structure of the system and former prefilter solution, an optimization problem has been designed to give us the optimum pre-filter. The designed problem is based on minimization of the estimation error of ambiguities inherent to ICA in reconstruction of the data after separation. The optimization problem is mathematically solved and a set of optimized coefficients are obtained. Among the obtained set as optimum coefficients, optimum coefficients are acquired... 

A Multiplicative Patchwork Method (MPM) for audio watermarking is proposed in this paper. In order to embed watermark data within the host signal, two subsets of the host signal features are selected using two secret keys. Then, watermark data is inserted simply by multiplying one subset and leaving the other one unchanged. In order to have an error free detection in attack-free case, embedding is performed in the selected frames of the host signal which satisfies a certain condition. This method is implemented in the wavelet domain and approximation coefficients are used for data embedding. Furthermore, the inaudibility of watermark insertion is controlled using iterative approach aided by... 

This paper presents a Multiplicative Patchwork Method (MPM) for audio watermarking. The watermark signal is embedded by selecting two subsets of the host signal features and modifying one subset multiplicatively regarding the watermark data, whereas another subset is left unchanged. The method is implemented in wavelet domain and approximation coefficients are used to embed data. In order to have an error-free detection, the watermark data is inserted only in the frames where the ratio of the energy of subsets is between two predefined values. Also in order to control the inaudibility of watermark insertion, we use an iterative algorithm to reach a desired quality for the watermarked audio... 

This paper proposes a Distant Speech Recognition system based on a novel speaker Localization and Beamforming (SRLB) algorithm. To localize the speaker an algorithm based on Steered Response Power by utilizing harmonic structures of speech signal is proposed. This new scheme has the ability of speaker verification by fundamental frequency variation: therefore it can be utilized in the design of a speech recognition system for verified speakers. Then the performance of the Farsi speech recognition engine is evaluated under notorious conditions of noise and reverberation. Simulation results and tests on real data shows that by utilizing proposed localization scheme, recognition accuracy...