考虑通道切换延迟的WDM-EPON IPACT网络性能分析

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在现代光网络技术中,WDM(波分复用)Ethernet Passive Optical Networks (EPON)作为一种重要的接入技术,通过在光网络单元中引入可调光学组件来实现上行链路的多波长统计复用。这种设计初衷是提高带宽利用率,然而,这些可调组件的开关延迟(Switch Latency,SL)成为了一个关键因素,它直接影响了网络的性能和效率。 IPACT(Interleaved Polling with Adaptive Cycle Time)是一种用于WDM EPON的高效调度算法,其基本原理是通过动态调整循环时间来平衡各个站点的数据传输需求。然而,当考虑SL时,原有的IPACT模型需要进行扩展。这是因为每个波长数据包在经过可调组件时,由于SL的存在,可能需要额外的时间等待通道切换,这可能导致整体的传输延迟增加,从而影响数据传输速率和吞吐量。 本研究论文分析了SL对IPACT网络性能的影响,构建了一个新的数学模型,考虑了SL对数据传输时间、冲突概率以及整体服务质量(QoS)的具体影响。通过对SL的量化和纳入模型,研究人员能够更好地预测和优化网络性能,确保在保证服务质量的同时,最大化带宽利用率。 此外,该工作还探讨了SL对不同应用场景下的性能变化,例如,对于突发性数据流量或实时业务,SL的影响可能更为显著。通过仿真和实验验证,作者揭示了SL对IPACT算法的最佳配置参数和策略,这对于实际网络的设计和优化具有重要意义。 这项研究对于理解和优化WDM EPON在面对SL挑战时的网络性能至关重要,有助于网络运营商和系统设计者针对具体的应用场景,制定出更有效的网络管理策略,提升整个系统的运行效率和用户体验。

Please revise the paper:Accurate determination of bathymetric data in the shallow water zone over time and space is of increasing significance for navigation safety, monitoring of sea-level uplift, coastal areas management, and marine transportation. Satellite-derived bathymetry (SDB) is widely accepted as an effective alternative to conventional acoustics measurements over coastal areas with high spatial and temporal resolution combined with extensive repetitive coverage. Numerous empirical SDB approaches in previous works are unsuitable for precision bathymetry mapping in various scenarios, owing to the assumption of homogeneous bottom over the whole region, as well as the limitations of constructing global mapping relationships between water depth and blue-green reflectance takes no account of various confounding factors of radiance attenuation such as turbidity. To address the assumption failure of uniform bottom conditions and imperfect consideration of influence factors on the performance of the SDB model, this work proposes a bottom-type adaptive-based SDB approach (BA-SDB) to obtain accurate depth estimation over different sediments. The bottom type can be adaptively segmented by clustering based on bottom reflectance. For each sediment category, a PSO-LightGBM algorithm for depth derivation considering multiple influencing factors is driven to adaptively select the optimal influence factors and model parameters simultaneously. Water turbidity features beyond the traditional impact factors are incorporated in these regression models. Compared with log-ratio, multi-band and classical machine learning methods, the new approach produced the most accurate results with RMSE value is 0.85 m, in terms of different sediments and water depths combined with in-situ observations of airborne laser bathymetry and multi-beam echo sounder.

2023-02-18 上传

3)A digital clock consists of a screen to display the time and a dial for setting in turn the year, month, day, hour and minute. Twisting the dial to the left reduces by one the value being changed but twisting it to the right increases it by one. Pushing the dial alters which value is being adjusted. At first, it is the year but after the dial is pushed once, it is the month, then after the dial is pushed again, it is the day and so on. Imagine the clock is represented by a class with attributes year, month, day etc. The following is what the code for a method rotateDialLeft() might look like. public void rotateDialLeft() { if (mode == YEAR_MODE) { year--; } else if (mode == MONTH_MODE) { month--; } else if (mode == DAY_MODE) { day--; } else if (mode == HOUR_MODE) { hour--; } else if (mode == MINUTE_MODE) { minute--; } } The code for rotateDialRight() is similar. Apply the Open-Closed Principle to explain why the above code is unsatisfactory from the design viewpoint, considering the possibility of future change to the code, giving an example of such a change. 5)Give the code required for the classes introduced in question 3), focusing on the code for a method selectState() which changes the value that is being adjusted from years to months. Make it clear in which classes the code is to be found. Assume the existence of other methods that are needed such as getMonthSetUpState(). 8)Suppose that in a multiplayer role-playing game, a class Client has a dependency to an interface Fighter with public methods attack(), defend() and escape(). The game designer now wishes for Client to use a class Wizard with three different but equivalent public methods castDestructionSpell(), shield() and portal(). Explain how it is possible to do this using an appropriate design pattern.

2023-06-03 上传