Forward Error Control System Performance of Maximum Free Distance Convolutional Codes with Different Modulation Schemes

Forward Error Control (FEC) based on Convolution Encoders with Viterbi decoding is a good methodology to decrease the effect of Additive Gaussian Noise residing inside digital data transmissions channel. In this paper a Convolutional encoders with maximum free distance and different constraint lengths have been tested with AWGN channel effect using MATLAB. The performance and analysis has done by changing rates of Convolutional encoders and different constraint lengths and take in consider QPSK, 16-QAM and 64-QAM as modulation schemes.nbs

Error Control pada Jaringan Wireless ATM Berbasis CDMA Menggunakan Kode Concatenated

Penerapan sistem telekomunikasi bergerak generasi ketiga memerlukan suatu penelitian intensif di berbagaibidang penelitian. Salahsatunya adalah mengenai skema error kontrol yang cocok untuk diterapkan. Padapeneltian ini dievaluasi mengenai unjuk kerja dari suatu bagian sistem error kontrol pada jaringan wirelessATM berbasis CDMA menggunakan kode concatenated, yaitu lapisan fisiknya dengan menggunakanpengkodean Reed Solomon sebagai inner code dan pengkodean konvolusi sebagai outer code. Unjuk kerja yangditeliti adalah nilai bit error rate (BER) yang dapat dicapai oeleh error control tersebut tersebut. Untuk itudilakukan suatu simulasi dari suatu sumber ke penerima dengan menggunakan metode akses CDMA. Sumberberupa user yang membangkitkan paket CBR dan VBR. Hasil penelitian menunjukan bahwa concatenated codedengan menggunakan kode konvolusi dengan rate R=1/3 mempunyai kemampuan untuk diterapkan padajaringan wirless ATM, dengan jumlah paket = 200 palet, teknik pengkodean tersebut mampu mencapai errorfree pada Eb/No = 10 dB, sedangkan dengan jumlah paket = 100 paket mampu dicapai pada Eb/No = 9 d

Synthesis of Minimal Error Control Software

Software implementations of controllers for physical systems are at the core of many embedded systems. The design of controllers uses the theory of dynamical systems to construct a mathematical control law that ensures that the controlled system has certain properties, such as asymptotic convergence to an equilibrium point, while optimizing some performance criteria. However, owing to quantization errors arising from the use of fixed-point arithmetic, the implementation of this control law can only guarantee practical stability: under the actions of the implementation, the trajectories of the controlled system converge to a bounded set around the equilibrium point, and the size of the bounded set is proportional to the error in the implementation. The problem of verifying whether a controller implementation achieves practical stability for a given bounded set has been studied before. In this paper, we change the emphasis from verification to automatic synthesis. Using synthesis, the need for formal verification can be considerably reduced thereby reducing the design time as well as design cost of embedded control software. We give a methodology and a tool to synthesize embedded control software that is Pareto optimal w.r.t. both performance criteria and practical stability regions. Our technique is a combination of static analysis to estimate quantization errors for specific controller implementations and stochastic local search over the space of possible controllers using particle swarm optimization. The effectiveness of our technique is illustrated using examples of various standard control systems: in most examples, we achieve controllers with close LQR-LQG performance but with implementation errors, hence regions of practical stability, several times as small.Comment: 18 pages, 2 figure

Real-time Error Control for Surgical Simulation

Objective: To present the first real-time a posteriori error-driven adaptive finite element approach for real-time simulation and to demonstrate the method on a needle insertion problem. Methods: We use corotational elasticity and a frictional needle/tissue interaction model. The problem is solved using finite elements within SOFA. The refinement strategy relies upon a hexahedron-based finite element method, combined with a posteriori error estimation driven local $h$-refinement, for simulating soft tissue deformation. Results: We control the local and global error level in the mechanical fields (e.g. displacement or stresses) during the simulation. We show the convergence of the algorithm on academic examples, and demonstrate its practical usability on a percutaneous procedure involving needle insertion in a liver. For the latter case, we compare the force displacement curves obtained from the proposed adaptive algorithm with that obtained from a uniform refinement approach. Conclusions: Error control guarantees that a tolerable error level is not exceeded during the simulations. Local mesh refinement accelerates simulations. Significance: Our work provides a first step to discriminate between discretization error and modeling error by providing a robust quantification of discretization error during simulations.Comment: 12 pages, 16 figures, change of the title, submitted to IEEE TBM

Automatic-repeat-request error control schemes

Error detection incorporated with automatic-repeat-request (ARQ) is widely used for error control in data communication systems. This method of error control is simple and provides high system reliability. If a properly chosen code is used for error detection, virtually error-free data transmission can be attained. Various types of ARQ and hybrid ARQ schemes, and error detection using linear block codes are surveyed

A practical scheme for error control using feedback

We describe a scheme for quantum error correction that employs feedback and weak measurement rather than the standard tools of projective measurement and fast controlled unitary gates. The advantage of this scheme over previous protocols (for example Ahn et. al, PRA, 65, 042301 (2001)), is that it requires little side processing while remaining robust to measurement inefficiency, and is therefore considerably more practical. We evaluate the performance of our scheme by simulating the correction of bit-flips. We also consider implementation in a solid-state quantum computation architecture and estimate the maximal error rate which could be corrected with current technology.Comment: 12 pages, 3 figures. Minor typographic change