It is well-known that a biometric fuzzy vault can be constructed by applying an error correcting code (ECC) to a biometric signal. This is attractive because authentication only requires the check bits of the ECC to b...
详细信息
ISBN:
(纸本)9781424452798
It is well-known that a biometric fuzzy vault can be constructed by applying an error correcting code (ECC) to a biometric signal. This is attractive because authentication only requires the check bits of the ECC to be stored on the access control device, whereas the personal biometric traits need not be stored. For a given coding rate, the ECC attempts to correct the errors between an enrollment biometric and the provided probe, and authenticates if it is successful in doing so. Unfortunately, most implementations of biometric fuzzy vaults have very poor robustness to the inherent noisiness of biometric measurements. In this paper, we provide ECC design considerations for secure biometric systems, which provide both better robustness and greater security. In particular, for any feature extraction algorithm, we propose to reorder the feature bits according to their reliability, and associate the reliable bits with high-degree variable nodes in the graph of the ECC. Further, the reliability of a bit is measured at enrollment and used to initialize the ECC decoding. Experiments on an extensive database show considerable reduction in the false reject rate, while restricting the successful attack rate to a very low value.
In this paper, we propose an adaptive multi-hop communication protocol based on transmission power control and error correction coding to achieve energy efficiency in wireless ad-hoc network. This study is important i...
详细信息
ISBN:
(纸本)9780769537146
In this paper, we propose an adaptive multi-hop communication protocol based on transmission power control and error correction coding to achieve energy efficiency in wireless ad-hoc network. This study is important in extending battery lifetime and consequently the lifetime of nodes and the network. We consider multi-hop communication between pair of nodes where packet needs to be re-transmitted when transmission error or packet loss occurs. Based on the quality of the communication channel (bit error rate and bandwidth) and characteristics of the packet to be transmitted, we adaptively choose the most energy efficient transmission power level and error correction coding. Simulation shows that the proposed algorithm can save significant amount of energy, reduce packet loss rate and potentially the end-to-end packet delay.
In this work we analyse the performance of a joint coding-precoding scheme for OFDM systems over fading channels. The design of the precoder is based on the information redistribution of the input modulated symbols am...
详细信息
ISBN:
(纸本)9781424425167
In this work we analyse the performance of a joint coding-precoding scheme for OFDM systems over fading channels. The design of the precoder is based on the information redistribution of the input modulated symbols amongst all the output precoded symbols. The proposed precoder decreases the variance of the instantaneous noise power at the receiver produced by the channel variability. In this sense, the noise at the output of the receiver deprecoding block can be considered as gaussian causing an improvement in the performance of the channel coding scheme employed in the system. The proposed system is evaluated under realistic radio channels which present multipath frequency-selective fadings and are affected by Doppler spread.
This paper discusses the impact of interleaving and error correction coding on TCP throughput performance. Bulk TCP data transfers over an Ideal two-state fading channel are considered. Results are obtained through si...
详细信息
ISBN:
(纸本)9806560477
This paper discusses the impact of interleaving and error correction coding on TCP throughput performance. Bulk TCP data transfers over an Ideal two-state fading channel are considered. Results are obtained through simulations of single bulk TCP transfers over high rate and large delay links. The simulation model incorporates effects of interleaving and error correction coding. Examination of the simulation results show that TCP with the SACK (selective acknowledgment) option achieves higher throughput for channels with correlated errors, in comparison to channels with uncorrelated errors. The simulation results indicate that proper selection of interleaving and errorcorrection parameters can improve TCP throughput in cases of high error rates. A larger improvement is seen in case of longer delay links. The simulations also indicate that Improper selection of Interleaving and errorcorrection parameters can further degrade TCP throughput for single flows. In addition, the results show that over-interleaving can lead to performance loss as connection delay becomes large.
This paper studies video streaming system over a wireless medium. The major challenge is to provide a robust link along the transmission/transport path and most importantly through noisy channels/networks that could a...
详细信息
ISBN:
(纸本)9781424435098
This paper studies video streaming system over a wireless medium. The major challenge is to provide a robust link along the transmission/transport path and most importantly through noisy channels/networks that could add or drop bytes by unforeseeable factors. As a remedy for this phenomenon, we combine forward errorcorrection, blind compensation and traffic shaping to improve the over all performance. We report on the experiments on this unique performance improvement method. The results of our study can find applications in WiMax and AVCP.
In joint source-channel arithmetic coding (JSCAC) schemes, additional redundancy may be introduced into an arithmetic source code in order to be more robust against transmission errors. The purpose of this work is to ...
详细信息
In joint source-channel arithmetic coding (JSCAC) schemes, additional redundancy may be introduced into an arithmetic source code in order to be more robust against transmission errors. The purpose of this work is to provide analytical tools to predict and evaluate the effectiveness of that redundancy. Integer binary Arithmetic coding (AC) is modeled by a reduced-state automaton in order to obtain a bit-clock trellis describing the encoding process. Considering AC as a trellis code, distance spectra are then derived. In particular, an algorithm to compute the free distance of an arithmetic code is proposed. The obtained code properties allow to compute upper bounds on both bit error and symbol error probabilities and thus to provide an objective criterion to analyze the behavior of JSCAC schemes when used on noisy channels. This criterion is then exploited to design efficient error-correcting arithmetic codes. Simulation results highlight the validity of the theoretical error bounds and show that for equivalent rate and complexity, a simple optimization yields JSCACs that outperform classical tandem schemes at low to medium SNR.
Displayed gray level of a plasma display panel (PDP)is often different from the intended target gray level due to the variation of the line load (the number of on-cells on a scan line). The conventional gray level gen...
详细信息
Displayed gray level of a plasma display panel (PDP)is often different from the intended target gray level due to the variation of the line load (the number of on-cells on a scan line). The conventional gray level generation algorithm does not take this difference into consideration and may deteriorate the displayed image quality. In this paper, luminance ratio variations that depend on the line load are formulated as the third-order regression equations for red, green and blue colors, respectively. Based on these equations, this paper proposes a new gray-level generation algorithm to reduce gray-level errors caused by the variation of the line load. The proposed algorithm performs the conventional algorithm three times with new weight vectors (i.e., the expected gray levels of subfields) adjusted based on the-detected error of the previous run of the conventional algorithm. Simulations and experiments with a 50-in PDP show significant error reductions, including a 75.6% improvement of the mean absolute error evaluated with nine video sequences.
The sector failure rate (SFR) is extremely small at normal operating conditions of hard disk drives. In practice, it cannot be obtained by counting as that would require prohibitively large simulation times. Therefore...
详细信息
The sector failure rate (SFR) is extremely small at normal operating conditions of hard disk drives. In practice, it cannot be obtained by counting as that would require prohibitively large simulation times. Therefore, appropriate statistical models characterizing the distribution of error symbols are used in order to estimate the SFR. In this paper, we look at the underlying philosophy of existing estimation methods and classify them into macroscopic and microscopic types. We observe that the microscopic approach is well suited for certain iterative channels.
Maximum-likelihood (AIL) estimation of long chaotic sequences is generally statistically inefficient. Therefore, as the length of the sequences increase we do not obtain the usual Nil. behavior of consistency and norm...
详细信息
Maximum-likelihood (AIL) estimation of long chaotic sequences is generally statistically inefficient. Therefore, as the length of the sequences increase we do not obtain the usual Nil. behavior of consistency and normality. We discuss here a specific class of chaotic sequences for which consistency is preserved. The itineraries of the chaotic sequences in this class are derived from a set of binary code words. As a result, we are able to guarantee a minimal Hamming distance between them which increases linearly with the sequences length. In other words, pairs of sequences from this class have a non vanishing normalized Hamming distance between their itineraries as their length goes to infinity. We derive expressions related to the associated Euclidean distance between these chaotic sequences. Using these expressions we show that the condition for consistent estimation of a sequence from the class is satisfied with probability 1. Throughout the paper, we use the discrete-time symmetric tent chaotic sequences as an example and the expressions are derived for this specific case. We argue, however, that our results apply for a wider class of chaotic sequences. We mention the applicability of the work to the field of error-correcting codes for analog signals. However, it may be of interest for readers working on other aspects of chaotic maps as well.
In this paper, a method to design regular (2, d(c))-LDPC codes over GF(q) with both good waterfall and error floor properties is presented, based on the algebraic properties of their binary image. First, the algebraic...
详细信息
In this paper, a method to design regular (2, d(c))-LDPC codes over GF(q) with both good waterfall and error floor properties is presented, based on the algebraic properties of their binary image. First, the algebraic properties of rows of the parity check matrix H associated with a code are characterized and optimized to improve the waterfall. Then the algebraic properties of cycles and stopping sets associated with the underlying Tanner graph are studied and linked to the global binary minimum distance of the code. Finally, simulations are presented to illustrate the excellent performance of the designed codes.
暂无评论