Interleaved coding and sequential transmission scheme for packet‐level forward error correction over burst loss channels

Burst packet loss is a common problem over wired and wireless networks and leads to a significant reduction in the performance of packet‐level forward error correction (FEC) schemes used to recover packet losses during transmission. Traditional FEC interleaving methods adopt the sequential coding‐interleaved transmission (SCIT) process to encode the FEC packets sequentially and reorder the packet transmission sequence. Consequently, the burst loss effect can be mitigated at the expense of an increased end‐to‐end delay. Alternatively, the reversed interleaving scheme, namely, interleaved coding‐sequential transmission (ICST), performs FEC coding in an interleaved manner and transmits the packets sequentially based on their generation order in the application. In this study, the analytical FEC model is constructed to evaluate the performance of the SCIT and ICST schemes. From the analysis results, it can be observed that the interleaving delay of ICST FEC is reduced by transmitting the source packets immediately as they arrive from the application. Accordingly, an Enhanced ICST scheme is further proposed to trade the saved interleaving time for a greater interleaving capacity, and the corresponding packet loss rate can be minimized under a given delay constraint. The simulation results show that the Enhanced ICST scheme achieves a lower packet loss rate and a higher peak signal‐to‐noise‐ratio than the traditional SCIT and ICST schemes for video streaming applications.     

Generalized solution to symbol error probability integral containing over different fading models

This paper presents a generalized solution to the symbol error probability (SEP) integral containing the product of two Gaussian Q‐functions . Numerical integration technique is first used to approximate the polar form of as a sum of exponentials. This approximation is then used to derive a closed‐form solution to the related SEP integral. Due to the exponential nature of the approximation, solution to the integral is expressed in terms of moment generating function (MGF) of a fading distribution. Therefore, the solution to integral exists for all fading distributions which have well‐defined MGF. The mathematical complexity of the proposed solution is directly proportional to the complexity of MGF expression. For most of the fading models, the corresponding MGF involves power or exponential functions, which guarantees algebraic simplicity of the proposed solution. Further, this generalized solution is used to evaluate the SEP of various modulation schemes over different fading channels. Various computer simulations run in MATLAB for wide range of scenarios confirm the accuracy of the proposed approximation and solution.     

QoS‐based adaptive error control for wireless networks

Wireless channels are highly affected by unpredictable factors such as cochannel interference, adjacent channel interference, propagation path loss, shadowing, and multipath fading. The unreliability of media seriously degrades the transmission quality. Automatic Repeat reQuest (ARQ) and Forward Error Correction (FEC) schemes are frequently used in wireless environments to reduce the high bit error rate of the channel. In this paper, we propose an adaptive error‐control scheme for wireless networks on the basis of dynamic variation of error‐control strategy as a function of the channel bit error rate, desired QoS, and number of receivers. Reed–Solomon codes are used throughout this study because of their appropriate characteristics in terms of powerful coding and implementation simplicity. Simulation results show that our adaptive error‐control protocol decreases the waste of bandwidth due to retransmissions or extra coding overheads while satisfying the QoS requirements of the receivers. Copyright © 2002 John Wiley & Sons, Ltd.     

Performance of Markov models for frame‐level errors in IEEE 802.11 wireless LANs

Interference among different wireless hosts is becoming a serious issue due to the growing number of wireless LANs based on the popular IEEE 802.11 standard. Thus, an accurate modeling of error paths at the data link layer is indispensable for evaluating system performance and for tuning and optimizing protocols at higher layers. Error paths are usually described looking at sequences of consecutive correct or erroneous frames and at the distributions of their sizes. In recent years, a number of Markov‐based stochastic models have been proposed in order to statistically characterize these distributions. Nevertheless, when applied to analyze the data traces we collected, they exhibit several flaws. In this paper, to overcome these model limitations, we propose a new algorithm based on a semi‐Markov process, where each state characterizes a different error pattern. The model has been validated by using measures from a real environment. Moreover, we have compared our method with other promising models already available in the literature. Numerical results show that our proposal performs better than the other models in capturing the long‐term temporal correlation of real measured traces. At the same time, it is able to estimate first‐order statistics with the same accuracy of the other models, but with a minor computational complexity. Copyright © 2009 John Wiley & Sons, Ltd.     

Performance modeling of FEC‐based unequal error protection for H.264/AVC video streaming over burst‐loss channels

Unequal error protection systems are a popular technique for video streaming. Forward error correction (FEC) is one of error control techniques to improve the quality of video streaming over lossy channels. Moreover, frame‐level FEC techniques have been proposed for video streaming because of different priority video frames within the transmission rate constraint on a Bernoulli channel. However, various communication and storage systems are likely corrupted by bursts of noise in the current wireless behavior. If the burst losses go beyond the protection capacity of FEC, the efficacy of FEC can be degraded. Therefore, our proposed model allows an assessment of the perceived quality of H.264/AVC video streaming over bursty channels, and is validated by simulation experiments on the NS‐2 network simulator at a given estimate of the packet loss ratio and average burst length. The results suggest a useful reference in designing the FEC scheme for video applications, and as the video coding and channel parameters are given, the proposed model can provide a more accurate evaluation tool for video streaming over bursty channels and help to evaluate the impact of FEC performance on different burst‐loss parameters. Copyright © 2014 John Wiley & Sons, Ltd.     

Cooperative wireless localization based on weighting for vector‐addition error

Localization error occurrence due to a position ambiguity is a very critical problem in wireless distributed cooperative localization, which may, in turn, affect the reliability of the localization of the whole or a major portion of the network. In this paper, we formulate a two‐dimensional cooperative localization model via graph partition in arbitrary topologies while considering the cooperative node's (or neighbor's) position ambiguity. Based on this model, we establish a robust algorithm, named weighted factor graph (FG)‐based cooperative localization algorithm, by mapping local topologies into the FG and by incorporating the vector‐addition error as the weight. The vector‐addition error includes the measurement error and the neighbor's position ambiguity, simultaneously. The optimal weight is derived theoretically according to the statistic properties of the vector errors and the joint probability density function. Theoretical analysis and numerical results indicate that the proposed algorithm can acquire higher level of accuracy for localization in various topology scenarios in comparison with some typical algorithms. Copyright © 2014 John Wiley & Sons, Ltd.     

Exact closed‐form symbol error rate of arbitrary rectangular M‐QAM over Rayleigh fading for two‐branch transmit diversity

By using a ‘pre‐averaging method’, we successfully derive an exact closed‐form symbol error rate (SER) expression for the particular case of two transmit‐one receive antenna diversity system employing arbitrary rectangular M‐QAM signalling over flat Rayleigh fading. Fading between branches are assumed independent. Both identical and distinct branch powers are considered. The closed‐form SER obtained is in terms of elemental functions containing no unevaluated integrals nor lengthy and complicated transcendental functions. Simulation results show that square M‐QAM outperforms rectangular M‐QAM for a given size M. Monte Carlo simulation results are found in excellent agreements with theoretical results. Copyright © 2006 John Wiley & Sons, Ltd.