On the effects of the packet size distribution on FEC performance
On the effects of the packet size distribution on FEC performance
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数据包大小分布对 FEC 性能的影响
DOI：
10.1016/j.comnet.2005.09.006
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
G. Karlsson
中科院分区：
文献类型：
--
作者：
G. Dán;V. Fodor;G. Karlsson
对于像VBR视频这样的多媒体业务，平均丢失概率的知识不足以确定丢失对感知的视觉质量的影响以及对改善视觉质量的可能方式的影响，例如通过前向纠错（FEC）和错误隐藏。在本文中，我们研究了数据包大小分布如何影响数据包丢失过程，即，连续丢失的概率和分组块中丢失的分组数量的分布以及相关的FEC性能。我们提出了一个精确的数学模型的MMPP+MMPP/Er/1/K队列的丢失过程，并比较模型的结果进行模拟与其他各种数据包大小分布（PSD），其中包括，从互联网骨干网测量PSD。结果表明，与经验PSD的前三阶矩（均值、方差和偏度）相匹配的PSD解析模型可以用来评估真实的网络中FEC的性能。我们得出结论，指数PSD，虽然它不是一个最坏的情况下，是一个很好的近似PSD的今天的互联网来评估FEC的性能。我们还得出结论，分组大小分布影响分组丢失过程，从而FEC的效率主要在接入网络中，一个单一的多媒体流可能会影响复用行为。我们评估了PSD如何影响广泛使用的吉尔伯特模型的准确性来计算FEC性能，并得出结论，如果PSD的CoV较高，则吉尔伯特模型可以更好地捕获丢失相关性。
For multimedia traffic like VBR video, knowledge of the average loss probability is not sufficient to determine the impact of loss on the perceived visual quality and on the possible ways of improving it, for example by forward error correction (FEC) and error concealment. In this paper we investigate how the packet size distribution affects the packet loss process, i.e., the probability of consecutive losses and the distribution of the number of packets lost in a block of packets and the related FEC performance. We present an exact mathematical model for the loss process of an MMPP+MMPP/Er/1/K queue and compare the results of the model to simulations performed with various other packet size distributions (PSDs), among others, the measured PSD from an Internet backbone. The results show that analytical models of the PSD matching the first three moments (mean, variance and skewness) of the empirical PSD can be used to evaluate the performance of FEC in real networks. We conclude that the exponential PSD, though it is not a worst case scenario, is a good approximation for the PSD of today’s Internet to evaluate FEC performance. We also conclude that the packet size distribution affects the packet loss process and thus the efficiency of FEC mainly in access networks where a single multimedia stream might affect the multiplexing behavior. We evaluate how the PSD affects the accuracy of the widely used Gilbert model to calculate FEC performance and conclude that the Gilbert model can capture loss correlations better if the CoV of the PSD is high.