Interleaving

Convolutional codes are frequently used to correct errors in noisy channels. Viterbi algorithm is a wellknown maximum-likelihood algorithm for decoding of convolutional codes. They have rather good correctingcapability and perform well even on very noisy channels. In this paper we present our studies of impact of constrain length on the performance of convolutional CODEC in AWGN channel.

Spacing and interleaving approaches have attracted significant interest over the past few years, with research suggesting they have the potential to support both retention and transfer of learning. The small-scale study reported here, in conjunction with a review of the literature, was undertaken to explore the effect of interleaving and spacing in authentic classroom learning of concepts.

Code Division Multiple Access CDMA is one of the main players in the wireless market expected to ll the need for higher capacity Conventional or single user detection has thus far been the de modulation method of choice in CDMA receivers despite many shortcomings due to its simplicity Multiuser detectors on the other hand have the po tential for dramatically higher capacity at the cost of increased complexity In this paper we consider two stage detection schemes in a coded system and compare them to other suboptimum detectors We focus on the relatively simple two stage with the conventional rst stage detector and show that it has very good performance over the fading channel and is robust against the near far problem when error correction is used We then describe alterna tive receiver structures for two stage detectors in coded systems and present a novel user interleav ing scheme which o ers even further performance improvement over previous implementations

The research into series connection of dc–dc converters has been concentrating more recently on creating a high voltage low current string. However, the interleaving technique of series-connect photovoltaic (PV) module integrated converters (MICs) has not been sufficiently addressed so far. This paper proposes a low cost high performance interleaving technique based on series PV MICs to reduce the output voltage-ripples. With the reduced voltage-ripples, the size and cost of capacitors at grid connected inverters can be reduced. The proposed technique is capable of solving the problem for PV panels with mismatched operating conditions. Each PV panel is able to track its own maximum power point (MPP) which simultaneously delivers the maximum power for the system. The proposed technique is mathematically investigated based on boost (step-up) converters and validated by Simulink/Matlab simulation and experiment results. The MPP tracking (MPPT) algorithm is tested for a PV/battery charging system with satisfactory performances in both steady-state and transient responses with reduced voltage-ripples.


Read More: http://www.worldscientific.com/doi/abs/10.1142/S0218126614500455?prevSearch=%5BContrib%3A+Boyang+Hu%5D&searchHistoryKey=

Composite laminates subjected to out-of-plane loads develop damage modes that compromise the load-carrying capacity, as in the fuselage skin of an aircraft. Therefore, we aimed to improve the damage resistance and tolerance of carbon/epoxy thin non-crimp fabric (NCF) laminates by (a) reducing the ‘conventional’ ply-thickness (i.e. comparing thick- and thin-plies) (b) interleaving co-polyamide (CoPA) non-woven veils at the interlaminar regions of thin-ply systems. We devised an impact, compression after impact (CAI) and quasi-static indentation (QSI) experimental campaign, where computerized X-ray tomography provided detailed 3D insight on how matrix cracking, delamination and fibre failure interacted during impact and QSI.

Thin-ply laminates reduce the amount of matrix cracking and delamination at the cost of premature fibre breakage, therefore decreasing the damage tolerance. Interleaving CoPA veils arrests delamination onset and improves the residual strength with respect to the thin-ply baseline.

The performance of a communication system is mainly depending on channel between the receiver and the transmitter in the system. Therefore, the most important thing for communication is the channel which is affected by parameters such as noise, fading, shadowing, and interference. These effects complicate for the receiver to obtain the transmitted signal. Communication systems use coding and interleaving techniques to reduce or eliminate the disturbing effect of these channels. The graphical user interface (GUI) is a graphical development environment that provides designers with a variety of tools and facilities for their convenience. Recently, GUI based applications have been preferred in vocational and technical education. The development of such applications accelerates the learning process of the students by showing the effects of system's case changes. MATLAB is software that has proven its importance in vocational and technical education with its useful interface, the speed of calculations, and the ability to visualize data. The GUI, which is a component of MATLAB, decreases the complexity of the code in software and increases the clarity of the subject. In this study, a GUI based communication system training platform was realized in MATLAB according to the near to real time parameters. The results show that the developed training application instantly displays changes to the channel and is user-friendly for students. In addition, it is thought that the use of GUI interface in vocational and technical education will provide a tangible benefit.

Conventional DC-DC converters are widely used in non-conventional power conversions namely in solar and wind power generation systems. Since there is no filter inductor on output side, output current of cuk converter is pulsed, which is not desirable, so it is required to improve the quality of power when DC-DC converters are employed for transferring requisite amount of power. The objective of this paper is to analyze, simulate and examine the operation of interleaved cuk converter and to compare with conventional cuk converter using Fuzzy logic controller. The unwanted ripple content is diminished and reduction in settling time by implementing interleaved structure to cuk converter topology with current and voltage feedback control loop by using fuzzy logic controller. In this paper the proposal model gives high efficiency and gain with limited duty cycle and wide load variation range. The performance of this system is observed in MATLAB/SIMULINK SOFTWARE. Keywords: DC-DC converter, cuk configuration, interleaving technique, reduced current and voltage ripple, voltage feedback, fuzzy logic controller. I. INTRODUCTION The recent development of battery powered applications is improving the need of efficient step up dc-dc converters. Nowadays, step up conversion is widely used in many applications like Electric vehicles, Photovoltaic (PV) system, Uninterruptable power supplies (UPS) and fuel cell system. By paralleling the converters, the input current can be shared among inductors so that high reliability and efficiency in power electronic systems can be obtained. Cuk converter is one of the most versatile Buck-Boost converter topologies that is output voltage from converter can be both lower and higher than input voltage. The advantages of using cuk converter over the conventional Buck-Boost topology are continuous current at both input and output and low output voltage ripple with properly designed filter. The major disadvantage in the cuk converter is input current is high due to this inductor losses are maximum and by using the single switch throughout the operation so temperature and switching losses are also high. So to overcome theese disadvantages, we may place the two cuk converters in parallel i.e... Called INTERLEAVED TECHNIQUE.This topology possesses the advantages of both Buck and Boost converter. The main advantages of this Interleaved cuk converter are the high input current is divided into two halves due to the parallel connection and Temperature losses are reduced by using the two switches during the total time period of operation. The applications of interleaved cuk converter are in renewable power applications like in solar and wind power applications as voltage regulator in hybrid solar-wind energy system where input voltage depends on speed of wind and sun, it is used in self-regulating power supplies, consumer electronics, battery power systems, adaptive control applications and also used in power amplifier applications. In literature many researches has been done on conventional solutions for controller design of different DC-DC converters based on classical and modern control theory. Widely used classical control theory based controllers are PID controllers. These controllers require precise linear mathematical models and also fail to perform satisfactorily under parameter variation, non-linearity and load disturbance. In certain applications like finding operating point of a system, Fuzzy logic controller (FLC) has proven to be a good choice. Thee advantages of the Fuzzy logic controllers over PI, PID controllers are:

Interleaving switching techniques are well known
and widely used for minimizing the output current ripples of one
input source with several paralleled buck converters. For the case
to minimize the output current ripples of different paralleled
sources working with different dutycycles has never been taken
into account. This paper proposes a new switching technique to
minimize the output current ripples of multiple input sources
paralleled with buck converters. The proposed switching
technique is based on the peak-ripple cancellation with novel
phase shift determination algorithm. The feasibility and the
performance of the proposed switching technique are verified by
simulation results and hardware implementation. The proposed
switching technique can be used to harvest energy from PV.
MPPT algorithm is also tested for the proposed technique, which
would be used for integrating renewables into the smart grid."

One of the main requirements for battery charging applications is constant output voltage and fewer ripples in the output voltage. Boost converters are used in places where the magnitude of the supply voltage is low. But in conventional boost converters, the magnitude of ripple in both the input current and output voltage are high which is not desired. While the input current ripple is reduced in conventional boost converter, the size of the components used is large. In order to reduce the ripples along with reduction in the component size, interleaving concept used. This paper focusses on the operation of four phase interleaved boost converter both in open and closed loop schemes. In the closed loop operation, current control mode is employed because of its faster response to changes along with simpler compensation and high gain bandwidth compared to the voltage control mode. The simulation of the circuit is carried out in MATLAB/SIMULINK and the results are validated for both the schemes.

Conventional interleaving switching techniques are widely used to minimise the output current ripples of one input source with several paralleled DC-DC converters. The method of minimising the output current ripples of different paralleled renewable sources working with different duty cycles has never been considered and conventional interleaving techniques are no longer practical to meet requirements. This paper proposes a novel interleaving switching technique for multi-input sources using a novel phase shift method to reduce the current ripples, and further reduce the size/cost of inductors and capacitors needed for fi ltering. It has favourable advantages such as low cost and fast dynamic response. It is able to accommodate variable input voltages and duty cycles from each converter and the failures of one or more cells. The proposed switching technique is applicable to any type of buck-derived or boost-derived DC-DC converters integrated
with renewable sources. It can be used to implement maximum power point tracking applications for integrating renewable sources to the grid. In this paper, photovoltaic systems are adopted for analysis. The proposed technique is validated through detailed mathematical analysis, simulation
and implementation.

Resonant power supplies have the advantage over traditional pulse width modulation (PWM) converters due to their soft switching capabilities. In addition, the output current ripple can be reduced by using three phase interleaving structure. However, this structure also suffers from some disadvantages, such as resonant current imbalance. Most previous solutions have been focused on hardware as adding extra power switches, increasing the cost and volume of the converter. There are not many software solutions due to the difficulty in modeling unbalance three-phase. This paper will propose a smoothly resonant current balancing solution for the three-phase interleaved LLC structure which is based on controlling directly resonant current phase angles (CPAB). This proposed method shows better current balance and response than the old trigonometric current balancing (TCB) method. The proposed technique is also verified by a 48 V 3.6 kW prototype converter and its experimental results.

Power converter is a key component in micro-scale energy harvesting systems. Micro-scale energy harvesting has become an increasingly viable and promising area for powering ultra-low power systems. Switched-capacitor (SC) power converters that use capacitors as energy storage elements offer much better power density than switched-inductor counterparts and are thus attractive in low-power area-constrained applications. Switched-capacitor (SC) converters have shown tremendous promise in this regard due to favorable device utilization and scaling trends, and the emergence of high-density silicon-compatible capacitor technologies. With the rising integration levels used to increase digital processing performance, there is a clear need for multiple independent on-chip supplies in order to support per-IP or block power management. The growing demand for both performance and battery life in portable consumer electronics requires SoCs and power management circuits to be small, efficient, and dynamically powerful. This project first reviews various design techniques for implementing high density On-chip Switched-capacitor (SC) power converters and secondly suggests the best technique to solve aspects of power converter design: Area Density, Power Consumption & Efficiency.

The performances of a multicarrier modulation (COFDM) system in an urban mobile radio channel is analyzed using a computer-aided analysis tool called SPW. This multicarrier modulation system, with convolutional coding and interleaving, provides an extremely bandwidth efficient and multipath resistant transmission method. COFDM gives a remarkable performance in selective Rayleigh channels at a much higher bit rate than conventional systems

In this paper a new efficient interleaving methodology in which patient textual information is embedded in
medical images considering Magnetic Resonance Image, Ultrasonic image and CT images of that patient
body. The main disadvantages in traditional techniques to Embed patient information in medical images is
inability to withstand attacks and Bit Error Rate (BER) when maximum number of characters to be
embedded are absent in proposed algorithm. The New robust Embedding Techniques, Local Binary Pattern
(LBP) and Local Ternary Pattern (LTP) are used to embed the patient information in medical images. LBP
Technique is mainly used to provide the security for the patient information. Along with the security high
volume of patient information can be embedded inside the medical image using LTP technique. Statistical
parameters such as Normalized Root Mean Square Error, PSNR (Peak Signal to Noise Ratio) are used to
measure the reliability of the present technique. Experimental results strongly indicate that the present
technique with zero BER (Bit Error Rate), higher PSNR (Peak Signal to Noise Ratio), and high volume of
data embedding capacity achieved using LTP as compared with the other data embedding techniques. This
technique is found to be robust and watermark information is recoverable without distortion.

Recently, the demand for reliable and high-speed wireless communication has rapidly increased. Orthogonal frequency division multiplexing (OFDM) is a modulation scheme that is the newest competitor against other modulation schemes used for this purpose. OFDM is mostly used for wireless data transfer, although it may also be used for cable and fiber optic connections. However, in many applications, OFDM suffers from burst errors and high bit error rates. This paper presents the utilization of a helical interleaver with OFDM systems to efficiently handle burst channel errors and allow for Bit Error Rate (BER) reduction. The paper also presents a new interleaver, FRF, the initial letters of the authors’ names, for the same purpose. This newly proposed interleaver summarizes our previous experience with many recent interleavers. Fast Fourier transform OFDM (FFT-OFDM) and Discrete Wavelet Transform OFDM (DWT-OFDM) systems are used to test the efficiency of the suggested scheme in terms o...

OFDM with diversity and coding has been proposed as an effective means for achieving high-rates in wireless environments. Turbo codes have been shown to give near-capacity performance in additive white Gaussian noise (AWGN) channels and is being considered to enhance mobile wireless channel performance. In this paper, we present simulation results of an OFDM system with turbo coding. Comparisons with systems employing convolutional and Reed-Solomon (RS) codes are made. We first study diversity, interleaving and soft decoding for convolutional codes. The same structure is employed for turbo codes of similar complexity and varying word size. Even with a low constraint length, convolutional codes have the potential to outperform RS codes, provided that the interleaver and soft decoder are properly designed. We evaluate Turbo code performance under slow fading conditions and study the effects of changing word size. Increasing word size theoretically provides better interleaving between the two component codes. However, this advantage is less clear when the fading rate is significantly lower than the symbol rate, which is typical of the high data-rate system considered here. Under such conditions, the advantage of using two component convolutional codes in turbo codes is limited. A single convolutional code with higher constraint length may be a better choice

Performance evaluation of PMUs to confirm the consistency of phasor measurements is of a great importance since it promotes the interchangeability among PMUs from different manufacturers. This paper presents a method for evaluating the dynamic performance of PMUs when exposed to a step change of input signals. A phasor estimation scheme is proposed to achieve high accuracy of reference phasors.

We provide a performance comparisons between the capture division packet access (CDPA), a novel cellular packet-access architecture, and more classic systems based on the FDMA/TDMA scheme. The CDPA is a single-frequency interference-limited system in which the packet access scheme is integrated with the interference protection scheme, being the protection attained through packet retransmission and time diversity. The comparison is obtained by simulating the operation of the two schemes in a real cellular ...

In this paper we present a formal proof of total correctness for Infosoft e-Detailing 1.0 distributed presentation software using Is-abelle proof assistant. We model execution of a distributed software as a transition system with a global state that is composed of states of the system's components and show that under a certain progress assumption , after a presenter switches the current slide to a given target slide, the executions of this transition system reaches a state which all viewers (clients) can see the target slide.