Discrete Bit Research Articles

A novel color image steganography algorithm based on bit counting and multiple-base system

This paper proposes a novel color image steganography scheme using a compound sinusoidal discrete memristor map and bit counting method. Firstly, a new 2D compound sinusoidal discrete memristor map is designed to generate chaotic sequences with good randomness. Secondly, a new steganography algorithm combining bit counting and multiple-base system is proposed to reduce the distortion of the stego image. Finally, a new steganography framework based on the HSV model is designed to improve the security of the steganography scheme. Experimental and test results show that the proposed algorithm has good imperceptibility and can embed a large number of secret information.

Discrete R-Contiguous bit Matching mechanism appropriateness for anomaly detection in Wireless Sensor Networks

Resource exhaustion is one of the main challenges for the security of Wireless Sensor Networks (WSNs). The challenge can be addressed by using algorithms that are light weighted. In this paper use of light-weighted R-Contiguous Bit matching for attack detection in WSNs has been evaluated. Use of R-Contiguous bit matching in Negative Selection Algorithm (NSA) has improved the performance of anomaly detection resulting in low false positive, false negative and high detection rates. The proposed model has been tested against some of the attacks. The high detection rate has proved the appropriateness of R-Contiguous bit matching mechanism for anomaly detection in WSNs.

Efficient payload communications for IoT-enabled ViSAR vehicles using discrete cosine transform-based quasi-sparse bit injection

High-performance remote sensing payload communication is a vital problem in air-borne and space-borne surveillance systems. Among different remote sensing imaging systems, video synthetic aperture radar (ViSAR) is a new technology with lots of principal and managerial data which should be compressed, aggregated, and communicated from a radar platform (or a network of radars) to a ground station through wireless links. In this paper, a new data aggregation technique is proposed towards efficient payload transmission in a network of aerial ViSAR vehicles. Our proposed method is a combination of a recent interpolation-based data hiding (IBDH) technique and visual data transformation process using discrete cosine transform (DCT) which is able to outperform the reference method in terms of data aggregation ability.

Practical Multituple Packet Classification Using Dynamic Discrete Bit Selection

Multituple packet classification is one of the key technologies, and often the performance bottleneck in modern network devices. Devices such as firewalls demand fast packet classification on very complicated rule sets of large size, which is still challenging today. This paper proposes a practical packet classification algorithm named dynamic discrete bit selection (D2 BS), which achieves high classification speed while requiring low storage. D2 BS employs dynamic heuristic schemes at bit level, to explore the inherent characteristics of the rule sets. D2BS has been implemented on various platforms including Intel-architecture, multicore network processor, and FPGA, and is compared with the state-of-the-art solutions. Experimental results on real-life rule sets show that the memory storage required by D2BS is at least one to two orders of magnitude lower than that of the existing work, while the speed is much higher. With 64-byte Ethernet packet and 10K size ACL rule set, D2BS achieves a throughput over 10 Gbps on Cavium OCTEON CN5860 multicore network processor and over 135 Gbps on Xilinx Virtex-5 FPGA, which outperforms the existing work under the same test environment. All results promise that D2BS is a highly practical solution to satisfy vigorous requirements.

Discrete bit loading and power allocation for OFDMA downlink with minimum rate guarantee for users

Performance optimization of the communication networks with quality of service (QoS) considerations for all active users is of great practical importance in highly delay-sensitive applications like multipoint videoconferences and interactive video games. Using minimum data rate as the primary criterion for the QoS and the BER as a second one, in this paper, we provide the optimum discrete bit loading for an OFDMA downlink in which the QoS of all users are satisfied. We formulate the problem and solve the dual problem efficiently and without any suboptimality. Albeit the problem is non-convex, it has been shown that the duality gap tends zero in practical scenarios. We propose a novel approach to solve the dual problem by decomposing dual function and finding discrete rate allocation solution for practical applications. Also, we present a novel fast converging iterative algorithm to find the solution with much less complexity compared to that of well-known ellipsoid optimization algorithm. We analyze the complexity of these solutions, and using simulation results, show the superiority of our novel approach.

Secret information sharing algorithm based on CL multi-wavelet and combination bit plane for confidential communication

In view of the contradiction between capability, invisibility and robustness of the existing information hiding algorithms, a preprocessing algorithm for digital image based on CL( Chui-Lian) multi-wavelet transform and Combination Bit Plane( CBP) was proposed. Then the digital image preprocessed by CL multi-wavelet and CBP was taken as the cover image to embed secret information for confidential communication and image sharing. CL multi-wavelet transform could divide the cover image into four lowest resolution sub-images with different energy level. And CBP method could analyze the above four subimages into different bit planes as the final embedding regions. During the hiding procedure, robust information, secret information and fragile information could be embedded according to the energy and robustness characteristics of the embedding regions. The experimental results show that the robustness against several common attacks described in this paper has certain enhancement compared with other two methods when the embedding rate is 25%. The Peak Signal-to-Noise Ratio( PSNR) is increased by 37. 16% and 20. 00% respectively compared with Discrete Cosine Transform-Least Significant Bit( DCT-LSB)and Discrete Wavelet Transform-Least Significant Bit( DWT-LSB) algorithm.

20 Gb/s WDM-OFDM-PON over 20-km single fiber uplink transmission using optical millimeter-wave signal seeding with rate adaptive bit-power loading

We experimentally demonstrate the use of millimeter-wave signal generation by optical carrier suppression (OCS) method using single-drive Mach–Zehnder modulator as a light sources seed for 20Gb/s WDM-OFDM-PON in 20-km single fiber loopback transmission based on cost-effective RSOA modulation. Practical discrete rate adaptive bit loading algorithm was employed in this colorless ONU system to maximize the achievable bit rate for an average bit error rate (BER) below 2×10−3.

A Discrete Bit Loading Algorithm for FBMC/OQAM

In this letter the discrete rate maximization problem is investigated for FBMC/OQAM. The analysis reveals that if there is crosstalk certain bit allocations violate the power constraints. Aiming at ensuring the feasibility along with alleviating the complexity we have devised a novel iterative algorithm, which always converges. Simulation-based results show that the proposed algorithm performs close to the upper bound for high-coherence bandwidth channels. Under highly frequency selective channels the existing algorithms are not able to guarantee the target SER whereas our approach guarantees the QoS.

Dynamic Fly Performance of Air Bearing Sliders on Patterned Media

It is anticipated that a radical shift in design paradigm will be required in order to enable perpendicular magnetic recording (PMR) areal densities beyond 1 Tb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The shift in question will involve the use of advanced magnetic recording assist technologies such as patterned media, heat-assisted magnetic recording (HAMR), or microwave-assisted magnetic recording (MAMR). This paper is concerned with one of the challenges associated with the practical implementation of patterned media technology, namely, the impact of non-planarity, and shifts in pattern orientation (at data-servo transitions, in particular) on the dynamic fly performance of air bearing sliders. The nature of the latter challenge becomes apparent when considering that key to realizing recording areal densities exceeding 1 Tb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> will be air bearing sliders with superior dynamic fly stability at sub-2 nm clearances. Of the two types of patterned media technologies in development in the disk drive industry, namely, discrete track media (DTM) and bit patterned media (BPM), the former was chosen as a case study in this work.

Adaptive Discrete-Rate MIMO Communications with Rate-Compatible LDPC Codes

By using rate-compatible (RC) low density parity-check (LDPC) codes with adaptive modulation, we propose an adaptive, discrete-rate multiple-input multiple-output (MIMO) communications system. Given the high spectral efficiency of MIMO and the flexibility of an incremental redundancy (IR) protocol, combined with adaptive coding and modulation (ACM), the designed communications system is capable of achieving high data rates, for a low amount of overhead. A novel ACM power- and bit-allocation protocol is proposed to implement this system. We adapt the existing water-filling algorithm (WFA) to the discrete and finite bit rate constraints inherent in any communications system. This constrained WFA is shown to significantly improve the throughput performance of the communications system, over the case where a regular WFA is used. The results given in this paper show that the combination of IR and ACM with MIMO creates a wireless communications system that can easily adapt to channel fluctuations and provide high-data rates.

An Improved Water-filling Algorithm for Discrete Bit Allocation

An Improved Water-filling Algorithm for Discrete Bit Allocation

Dynamic Analysis Schemes for Flying Head Sliders Over Discrete Track Media

It is becoming increasingly important to analyze the static and dynamic characteristics of flying head sliders over discrete track media (DTM) and bit patterned media (BPM) using the molecular gas-film lubrication (MGL) equation. In this study, we obtained the dynamic characteristics of the air bearing of the read/write head by considering not only the stiffness and damping produced by the air film, but also the negative stiffness caused by the attractive van der Waals force; these quantities were calculated in the frequency domain using a perturbation method. The dependence of the dynamic characteristics on the groove depth and frequency were calculated numerically. Moreover, the cubic interpolated propagation (CIP) method, a highly accurate and numerically stable scheme, was extended to the two-dimensional MGL problem in the time domain and the time evolution of the pressure produced by a single projection on the running disk, which is the simplest configuration of BPM, was calculated numerically.

Influence of patterning fluctuation on read/write characteristics in discrete track and bit patterned media

The read/write characteristics of non-patterned media (NPM), discrete track media (DTM), and bit patterned media (BPM) are examined by modeling the magnetization distribution of NPM and patterning fluctuation of DTM. By comparing spin-stand measurement with calculation, the magnetization distribution of NPM was well characterized with a new Voronoi cell magnetic cluster model, in which the cluster size at the track edge, 〈 D edge〉, was larger than that at the track center, 〈 D center〉 by a factor of two. Based on an analysis of patterning fluctuations seen in SEM images of DTM, line-edge roughness (LER) was modeled as a long-wavelength center-line roughness (CLR) plus a short-wavelength line-width roughness (LWR). It was confirmed that the standard deviation of the patterning fluctuation was much smaller than that of the magnetic fluctuation for NPM. This allowed DTM to achieve higher off-track performance than NPM. By examining the 747 curves, it was revealed that DTM could have an advantage in track-density of up to approximately 25% assuming patterning fluctuations can be well controlled at high track density. In BPM, fabricating accurate dots is essential. The relationship between dot defect rate and patterning fluctuation was examined, and the maximum allowable standard deviation of LER was derived as 2 nm for achieving 1 Tbspi.

Asymmetric quantum error correction via code conversion

In many physical systems it is expected that environmental decoherence will exhibit an asymmetry between dephasing and relaxation that may result in qubits experiencing discrete phase errors more frequently than discrete bit errors. In the presence of such an error asymmetry, an appropriately asymmetric quantum code-that is, a code that can correct more phase errors than bit errors-will be more efficient than a traditional, symmetric quantum code. Here we construct fault tolerant circuits to convert between an asymmetric subsystem code and a symmetric subsystem code. We show that, for a moderate error asymmetry, the failure rate of a logical circuit can be reduced by using a combined symmetric asymmetric system and that doing so does not preclude universality. © 2008 The American Physical Society.

Framework for Analysis of Transmission Rate Scheduling for Wireless CDMA Data Networks

The optimal utilization of network resources and the capacity to fulfill quality of service requirements are key requirements for 3rd G networks operations. Several burst admission and transmission rate scheduling algorithms are proposed in the literature. In this study, we develop an analytical framework for the downlink transmission rate scheduling problem for CDMA networks employing discrete service bit rates. The framework uses the average downlink transmit power as the system state and develops a K-dimensional Markov chain representing all possible states in the system. In addition, the transition probabilities due to arrivals of burst requests are made a function of the power utilization and the average power required to support the new burst taking into account the path loss model. The study assumes a transmission rate assignment scheme where the maximum possible system bit rate is assigned given the current system state and the subscriber's eligibility profile for particular system service rates. The analytical model provides performance metrics such as system throughput, average power utilization, average number of simultaneous transmissions, burst request blocking probability, and mean burst service time. While the developed model is applicable for a general CDMA based network with arbitrary discrete system service bit rates, the model is evaluated for the example of a cdma2000 1xRTT network. A comparison between simulation and analytic results to assess the accuracy of the model is provided.

Multiple Access Channel Optimal Spectrum Balancing for Upstream DSL Transmission

Upstream DSL transmission suffers from in-domain crosstalk as well as out-of-domain or alien crosstalk. Here, the use of multi-user receiver signal coordination e.g. generalized decision feedback equalization, can lead to spectacular performance gains. This paper presents a transmission scheme, referred to as MAC-OSB, which focuses on the weighted rate sum capacity by joint receiver signal coordination and transmit spectrum coordination. The proposed scheme incorporates per-user total power constraints, spectral mask constraints and discrete bit or power loading constraints. Furthermore a low-complexity scheme, referred to as MAC-ISB, is presented which performs similar to MAC-OSB. Simulations show large performance gains over existing methods especially for scenarios with significant alien crosstalk

A Heuristic Optimal Discrete Bit Allocation Algorithm for Margin Maximization in DMT Systems

A heuristic optimal discrete bit allocation algorithm is proposed for solving the margin maximization problem in discrete multitone (DMT) systems. Starting from an initial equal power assignment bit distribution, the proposed algorithm employs a multistaged bit rate allocation scheme to meet the target rate. If the total bit rate is far from the target rate, a multiple-bits loading procedure is used to obtain a bit allocation close to the target rate. When close to the target rate, a parallel bit-loading procedure is used to achieve the target rate and this is computationally more efficient than conventional greedy bit-loading algorithm. Finally, the target bit rate distribution is checked, if it is efficient, then it is also the optimal solution; else, optimal bit distribution can be obtained only by few bit swaps. Simulation results using the standard asymmetric digital subscriber line (ADSL) test loops show that the proposed algorithm is efficient for practical DMT transmissions.

Patterned media for future magnetic data storage

One strategy to delay the onset of superparamagnetism and achieve magnetic storage densities approaching 1 Tb/in.2 is the use of lithographically patterned magnetic media. While one of the main advantages enjoyed by magnetic recording is low cost due to use of featureless media, there are several advantages that may be realized by patterning the medium in a hard disk drive. The commercial success of patterned media will of course depend on the relative costs and gains. In particular, there are three main types of disk patterning proposed, each requiring a different length scale of patterned feature. Patterning of servo marks for maintaining the head position on-track, the fabrication of discrete tracks, and the fabrication of discrete bits have all been proposed and will be discussed. For discrete bit recording single domain magnetic islands are required, and one approach to fabricating these, by depositing magnetic films onto prepatterned substrates, is described. The switching characteristics of the islands as compared to those of the full film, along with initial recording results are presented.

A hybrid time divisioning scheme for power allocation in DMT-based DSL systems

We propose an iterative waterfilling based multiuser Hybrid Time Divisioning (HTD) scheme for power allocation in DMT based DSL systems. The problem of finding the (user,subchannel) pairs which should transmit alone and the pairs which should transmit along with other users, so as to result in the maximum aggregate data rate achievable using time divisioning, has been considered. The proposed scheme Is a low complexity, sub-optimal solution to this problem. Results show that the HTD scheme can achieve better data rates than Iterative Waterfilling a well as Multiuser Discrete Bit Loading scheme (for high coupling coefficient values) with comparatively lesser complexity

Bit loading with BER-constraint for multicarrier systems

We present discrete adaptive bit loading algorithms for multicarrier systems with uniform (nonadaptive) power allocation operating in a frequency selective fading environment. The algorithms try to maximize the overall throughput of the system while guaranteeing that the mean bit error rate (BER) remains below a prescribed threshold. We also study the impact of imperfect subcarrier signal-to-noise ratio information on throughput performance. Results show that the proposed algorithms have approximately the same throughput and mean BER as the optimal allocation while having a significantly lower computational complexity relative to other algorithms with near-optimal allocations. Moreover, when compared with algorithms that employ approximations to water filling, the computational complexity is comparable while the overall throughput is closer to the optimum.