Wyniki 1-8 spośród 8 dla zapytania: authorDesc:"Raja Ali RIAZ"

Optimized RTL design and implementation of LZW algorithm for high bandwidth applications

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This paper presents a high-speed low-complexity Register Transfer Logic (RTL) design and implementation of the lossless Lempel-Ziv- Welch (LZW) algorithm on Xilinx Virtex II device family for High Bandwidth Applications. Comparative analysis of the proposed design with the established commercial data compression and decompression accelerators show that the proposed design offers comparatively high throughput 1.42 Gbits/s, elevated throughput/slice value 151.8 Kbytes/s/slice and lower operational power requirements 333 mW. Streszczenie. W artykule zaprezentowano nieskomplikowany, wysokiej częstotliwości projekt obwodu RTL oraz bezstratny algorytm LZW z układem Xilinx Virtex II. Porównano zaproponowany układ z komercyjnymi układami kompresji i stwierdzono, że umożliwia on przepustowość 1.42 Gbit/s przy poborze mocy 333 mW. (Optymalizowany układ RTL i algorytm LZW w zastosowaniach szerokopasmowych). Keywords: Lossless Compression, Lempel-Ziv-Welch, LUTs and Throughput/Slice. Słowa kluczowe: in the case of foreign Authors in this line the Editor inserts Polish translation of keywords. Introduction Data compression is a defined method or encoding technique which substantially reduces data size according to some existing rules [1, 2]. According to application area, two different classes of compression are used namely; lossy data compression and lossless data compression. Lossy data compression is generally used for applications like image and audio file types, where loss of information is less important [2]. Conversely, lossless data compression is most adaptable to applications like data transmission and storage, where it is important to keep all the information intact [2]. A wide variety of lossless compression algorithms have been proposed in the past which include Limpel and Ziv (L Z) codes [3], Huffman codes [4], Adaptive Huffman [5], Run-length encoding [6], Arithmetic coding [7], Multigroup compression method [8, 9], Shannon-Fano c[...]

Low Power and Area Efficient DCT Architecture for Low Bit Rate Communication

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In this paper a low power and area efficient DCT (Discrete Cosine Transform) pipelined architecture using multiplier-less method is presented for low bit rate communications such as videoconferencing in mobile devices. The multiplier-less multiplication is implemented by minimum number of additions, subtractions and shifts using CSD (Canonic Signed Digit) representation for fixed point DCT coefficient. Power reduction is achieved by minimizing both the number of arithmetic operations and data-path width. The proposed DCT architecture was implemented on a XILINX FPGA (Field-Programmable Gate Array). The results from power estimation show that our design is capable of reducing the power dissipation 5.5 times compared to the other DCT architectures for video streaming/video conferencing in portable devices. Streszczenie. W artykule zaprezentowano system komunikacji DCT )(Discrete Cosine Transform) o małej przepływności bitów charakteryzujący się małą mocą, dobrym pokryciem obszaru. System ma strukturę potokową. Ograniczenie mocy osiągnięto przez zmniejszenie operacji matematycznych oraz szerokości ścieżki danych. System zaimplementowano z wykorzystaniem elementów FPGA. (Architektura komunikacji DCP o małej mocy do małej przepływności danych) Keywords: Discrete Cosine Transform (DCT), Canonical Signed Digit (CSD), Multiplier-less Słowa kluczowe: komunikacja DCT, przepływność danych Introduction Many of today multimedia applications such as videoconferencing, internet video streaming and video-over wireless are most bandwidth consuming modes of communication. Efficient hardware is needed for these types of applications. The key features of hardware design are to consume very low power and low area to implement in portable small devices such as mobiles phones or cameras. Several international standards of image and video coders use compression techniques based on DCT which transform it in frequency domain. DCT algorithm has excessive numb[...]

Detection of ECG T-wave Alternans Using Maxima of Continuous-Time Wavelet Transform Ridges

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Prognostic utility of microvolt T-wave alternans (TWA) has been established since its clinical acceptance as marker for malignant ventricular arrhythmias, leading to sudden cardiac death. Accurate detection of TWA from surface ECG is a challenge because of invisible nature of the phenomenon. A novel TWA detection scheme based upon analysis of continuous time wavelet ridges (CTWR) of consecutive ventricular repolarization complexes is presented. The CTWR is computed using maxima of wavelet energy coefficients of continuous wavelet transform. Variety of simulated alternans waveforms, wavelet functions, frequency bands and noise levels are used to test the algorithm. The study concludes that CTWR can successfully characterize the alternation of cardiac repolarization and detect TWA phenomenon. Streszczenie. Diagnostyka sygnału TWA odgrywa du˙za˛ role˛ w badaniach jako marker arytmii powoduja˛cej zawał serca. Sygnał TWA jest wykrywany jako składowa sygnału elektrokardiogramu. W artykule opisano wykorzystanie cia˛głej transformaty falkowej do analizy tego sygnału. (Detekcja składowej TWA sygnału EKG bazuja˛ca na wykorzystaniu cia˛głej transformaty falkowej) Keywords: Continuous-Time Wavelet Transform, Detection, Electrocardiography (ECG), T-wave Alternans Słowa kluczowe: transformata falkowa, elektrokardiogram, sygnał TWA Introduction Electrocardiography (ECG) is an important clinical tool for diagnosis of cardiac diseases. It is commonly measured by placing the surface electrodes on a subject’s chest and recording the cardiac cellular potential variations. The measured voltages, graphically plotted as a function of time, represent sequential depolarization (P-wave and QRS complex) and repolarization (T-wave) of cardiac chambers. A single such heart beat is shown in Fig. 1(a). 0 0.1 0.2 0.3 0.4 0.5 0.6 -1 0 1 2 (a) ECG (mV) 0 1 2 3 4 5 -1 0 1 2 (b) ECG (mV) 0 1 2 3 4 5 -1 0 1 2 (c) time(sec) ECG (mv) P Q R S T[...]

Vertical Handover Triggering Condition Estimation for a Mobile Node Moving Out of a WiFi Cell

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In this work we estimate the handover trigger condition for a mobile node moving out of a WLAN cell roaming in a heterogeneous network environment by performing vertical handover using an end-to-end handover scheme. Determining the characteristics of the handover latency of the employed handover scheme we estimate the appropriate handover triggering instance so as to maximize the WiFi usage but limit the handover failure. The remaining time within the WiFi cell is determined through successive changes in received signal strength as the mobile node moves out of the WiFi coverage cell. Streszczenie. W pracy określono warunki trigera przełączania (handover) w mobilnym węźle komórki WLAN w środowisku sieci niejednorodnej. Określając opóźnienie przełączania określano sytuację przełączania tak aby maksymalizować użycie sieci WiFi ale ograniczać błąd przełączania. (Określanie warunków trigera przełączania typu handover w mobilnym węźle komórki WiFi) Keywords: Vertical handover, handover triggering condition estimation, handover failure probability. Słowa kluczowe: przełączanie - handover, trigger Introduction Determination of optimum handover initiation time is particularly of prime importance in the context of optimization of vertical handover from the WiFi network, which is characterized by fast and low cost of access but limited coverage range. Desire to maximize its usage is obvious, however, handover triggering close to the boundary region may lead to handover failure. Delaying the handover trigger for a moving out mobile node increases the probability of handover failure due to insufficient time for handover completion. For a given probability of handover failure the instance of handover trigger is estimated. In this work we use a geometrical model for handover triggering condition estimation. This work aims to estimate the handover triggering condition of the mobile node using an end-to-end vertical handover scheme. Geometrical an[...]

Estimation of Baseline Wander Characteristics in ECG Signals Using Adaptive Transversal Filter and Lomb's Periodogram Analysis

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A new technique is proposed to estimate the frequency and amplitude of baseline wander in ECG signals. The estimation has been performed in two stages. In the first stage, a QRS detector detects R peaks and signal samples between consecutive R peaks are passed through a weighted average adaptive filter. The cut-off frequency and order of the filter depends upon the time domain characteristics of the input samples and is automatically updated for each RR interval. In the second stage, Lomb’s periodogram is utilized to analyse the frequency response of the resultant unevenly sampled time series for estimating the baseline frequencies. These frequencies are then used to demodulate the signal for estimation of respective amplitudes. Results have been obtained using synthetic ECG signals with artificially introduced baseline wander containing single or multiple frequencies. The performance of the technique is evaluated by extracting baseline wander through three standard techniques and comparing the estimation errors. Streszczenie. W artykule opisano propozycje estymatora cz˛estotliwosci i amplitudy wahan osi podstawy dla sygnałów w badaniu EKG. Estymacja przebiega w dwóch etapach. Najpierw detektor QRS wykrywa impulsy R, a próbki sygnałów poddawane sa˛ filtracji w filtrze adaptacyjnym. W drugim kroku, korzystaja˛c z periodogramu Lomb’a, analizowana jest odpowiedz cze˛stotliwosciowa, be˛da˛ca w postaci nierównomiernie pobieranych próbek. Tym sposobem uzyskuje si ˛e estymacj ˛e cz˛estotliwosci odniesienia. Działanie algorytmu poddano weryfikacji na bazie symulowanych sygnałów EKG i porównano z trzema standardowymi technikami. (Estymacja charakterystyki przemieszczenia osi podstawy dla sygnałów EKG z wykorzystaniem filtru adaptacyjnego poprzecznego i analizy periodogramem Lomb’a). Keywords: Electrocardiogram, baseline wander, ECG preprocessing, estimation Słowa kluczowe: elektrokardiogram, w˛edrowanie osi podstawy, EKG, przetwarza[...]

The Q-Best Spreading Sequences for Low-Complexity DS-CDMA IEEE 802.15 UltraWideBand Systems in Dense Multipath Channels

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This paper presents an analysis for the selection of Q-Best spreading sequences of the synchronous Direct Sequence Code Division Multiple Access (DS-CDMA) UltraWideBand (UWB) system on the uplink using joint detection. It is shown that the time-domain cross correlation function between the spreading sequences is a prime interference measure for the synchronous DS-CDMA UWB users. Therefore auto and cross correlation funcitons of the spreading sequences, along with UWB IEEE 802.15 channel characteristics are amalgamated to obtain minimum Bit Error Rate (BER), using low complexity correlation joint detection scheme. Some well known classes of length Q sequences, such as m, Gold, Walsh and Random sequences are evaluated with respect to the aforementioned basic criteria. Explicitly, the performance of each sequence with length Q is shown in high Inter-Symbol Interference (ISI) and Multiple Access Interference (MAI) environment produced by dense multipath and multiuser. Streszczenie. W artykule przedstawiono analiz˛e metod rozpraszania widma z wykorzystaniem detekcji poła˛czen, dla metody doste˛powej DS-CDMA w poła˛czeniu z satelita˛ w systemie UltraWideBand. Wykazano, z˙e wyznaczenie funkcji korelacji przejscia dziedziny czasu mie˛dzy sekwencjami rozpraszania powinno stanowic główny czynnik pomiarowy dla u˙zytkowników systemu DS-CDMA UWB. W badaniach wykorzystano najlepiej znane klasy o długosci sekwencji Q (Gold, Walsh, Random, m). Ich działanie sprawdzono w ´srodowisku ISI oraz MAI stworzonym przez g˛esty zbiór wielu scie˙zek i wielu u˙zytkowników. (Sekwencja rozpraszania Q-Best w systemie DS-CDMA UWB IEEE 802.15 w kanałach wieloscie˙zkowych) Keywords: Spreading Sequences, DS CDMA, UWB, Dense Multipath Słowa kluczowe: sekwencja rozpraszania, DS-CDMA, UWB, spójna wielodro˙znosc. Introduction The Federal Communications Commission’s (FCC) ruling released the band spanning from 3.1 to 10.6 GHz in the USA for UltraWideBand UWB forms the basi[...]

Performance of Time Hopping Impulse Radio in Ultrawideband Propagation Channels: Implications of UWB and Diversity Order Selection

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In this treatise, we quantify the effects of the UltraWideBand (UWB) on Time Hopping (TH) Impulse Radio (IR) operating in UWB propagation channels environment in terms of bandwidth utilization through diversity order selection. We select L strongest MultiPath Components (MPC) from Nr resolvable MPCs using Maximal Ratio Combining (MRC) in order to achieve maximum performance gain in single and full load scenarios. Three classical detectors have being used for analysis purposes named Correlation (Corr), Zero Forcing Detector (ZFD) and Minimum Mean Square Error (MMSE). Our results suggest that the diversity order L of 20 achieves maximum gain of 18dB and 12dB in single and full load Nu of 63 users scenarios, having spreading factor Ns of 63 over no diversity configuration. Hence, MPCs with delays greater than the TH chip time Tc are resolved by synchronization with the initial path of the received signal gives maximum performance gain. Streszczenie. W artykule przedstawiono wyniki analizy dotycza.cej dzia.ania techniki Time Hopping Impulse Radio, zastosowanej w komunikacji Ultra WideBand, pod ka.tem stopnia wykorzystania doste.pnej przepustowosci. W analizie zastosowano trzy typy detektorow: Corr, ZFD, MMSE. Wyniki badan wskazuja., z.e gdy komponenty wielosciez.kowe o opoznieniach wie.kszych niz. okres Time Hopping sa. synchronizowane z pocza.tkiem odbieranego sygna.u, osia.gana jest maksymalna efektywnosc dzia.ania. (Dzia.anie techniki Time Hopping Impulse Radio w komunikacji Ultra Wide-Band . zastosowanie UWB oraz doboru stopnia ro.znorodnosci). Keywords: UWB, Diversity Order, Time Hopping, Impulse Radio S.owa kluczowe: UWB, stopien ro.znorodnosci, Time Hopping, Impulse Radio. Introduction UltraWideBand (UWB) radio communicates with baseband pulses of very short duration, typically on the order of a nanosecond, thereby spreading the energy of the radio signal very thinly (about a few ?ĘW per MHz) from near DC to a few Gigahertz. Because o[...]

ASIC Design Implementation of Memory Efficient Infinite Impulse Response UWB Equalizer

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Channel Equalization plays an important role in reducing distortion and Inter-Symbol Interference (ISI) to improve the quality of transmission in Ultra-Wide Band (UWB) channel. Many equalization techniques have been proposed in the past but the proposed techniques in this paper describes Infinite Impulse Response (IIR) equalizer architecture which halves the memory requirement of conventional IIR equalizers. This is achieved by exploiting the aperiodically repeated clusters of negative-exponentially decaying segments of Channel Impulse Response (CIR) and hence by providing a single delay- line between the input and output of the equalizer. Further this architecture is realized by implementing on Application Specific Integrated Circuit (ASIC) using Mentor Graphics IC Design tools. Mathematical modeling gives suitable parameters of the IIR Filter, followed by Register Transfer Level (RTL) Design using Very High Descriptive Language (VHDL), ASIC synthesis to TSMC 0.35um process technology, physical modeling using advanced layout techniques. The IIR equalization filter is designed using 8758 Metal Oxide Semi-conductor (MOS) transistors with core cell area of 0.406mm2. Streszczenie. W artykule zaproponowano architekturę ekwalizera NOI, która zmniejsza wymagania pamięci przy transmisji szerokopasmowej w układach ASIC. Zaprezentowano układ w technologii 35 nm z tranzystorami MOS przy powierzchni celki jądra 0.406 mm2. (Projekt szerokopasmowego ekwalizera NOI w układach ASIC) Keywords: Quasi-cyclic LDPC codes, Protograph LDPC codes, Low complexity LDPC codes, Vandermonde Matrix. Słowa kluczowe: układy ASIC - application specific integrated circuits, ekwalizer, filtry szerokopasmowe. Introduction The distinct clusters of dense multi path components in UWB systems results in Channel Impulse Response (CIR) potentially span over hundreds of transmitted symbols, hence imposing excessive memory requirements on the equalizers implementation. In [1] a g[...]

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