Constructions and analysis of crosstalk-free optical queues
Constructions and analysis of crosstalk-free optical queues
复制标题
无串扰光队列的构建与分析
DOI：
10.1109/hspr.2008.4734416
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
D. Lee
中科院分区：
文献类型：
--
作者：
Hao;Cheng;Jay Cheng;D. Lee
利用光开关和光纤延迟线（SDL）构造无冲突光队列的研究取得了一些新的进展。这些无冲突光队列中的许多由2 × 2交换机构成，因此遭受臭名昭著的串扰问题。为了减轻串扰问题，在文献中建议，应当避免同时将两个分组路由到相同的2 × 2交换机。具有这种特性的结构称为无串扰。本文的第一个贡献是将Deng和Lee的两步方法扩展为三步方法，将无冲突的SDL元素转换为无串扰的SDL元素。对于某些光队列，包括线性压缩器，线性解压缩器和非超越延迟线，可以采取额外的步骤（本文中的第四步），以进一步降低构造复杂度。对于这样的光队列，只需要比原始结构多一个2 × 2交换机。我们的第二个贡献，本文是提供最坏情况下的信号-噪声比（SNR）的分析，在原来的无冲突SDL元素和转换后的无串扰SDL元素。获得了两个SDL元素中最坏情况SNR的封闭形式表达式。这些表达式表明，在转换后的无串扰SDL元件的最坏情况下的SNR的增益是相当可观的。
There are several recent advances in the constructions of conflict-free optical queues using optical switches and fiber delay lines (SDL). Many of these conflict-free optical queues are constructed by 2 times 2 switches and thus suffer from the notorious crosstalk problem. To alleviate the crosstalk problem, it is suggested in the literature that one should avoid routing two packets to the same 2 times 2 switch at the same time. A construction with such a property is called crosstalk-free. Our first contribution of this paper is to extend the two-step method by Deng and Lee to a three-step method that converts a conflict-free SDL element into a crosstalk-free SDL element. For certain optical queues, including linear compressors, linear decompressors, and non-overtaking delay lines, an additional step (the fourth step in our paper) can be taken to further reduce the construction complexity. For such optical queues, one only needs one more 2 times 2 switch than the original construction. Our second contribution of this paper is to provide worst case analysis of the signal-to-noise ratio (SNR) in both the original conflict-free SDL element and the converted crosstalk-free SDL element. Closed-form expressions for the worst case SNRs in both SDL elements are obtained. These expressions show that the gain of the worst case SNR in the converted crosstalk-free SDL element is quite substantial.