在光群集交換網路中 基於效用函數的乏晰波長分配

Abstract

光群集交換(Optical Burst Switching, OBS)是一個充滿前景的技術，它利用了光通訊的優點以及資料流的多工處理使得它成為一個適合在全光網路環境下使用的技術。光群集交換不僅利用了光通訊的優點以及多工處理，更靠著它本身特殊的傳輸機制；控制封包(Control burst)以及推移時間(Offset time)來幫助它有效的提升資料吞吐量。雖然光群集交換可以有效的提升資料吞吐量，但當同時有多個控制封包預約的時間是重疊的，便會發生競爭進而導致資料的遺失也使得資料吞吐量降低。因此，適當而有效的波長分配演算法在提升光群集交換的資料吞吐量中扮演著重要的角色。 在本篇論文中，我們提出了基於效用函數上的乏晰波長分配演算法，此方法引入了四個重要的參數：替代指數、使用的光纖延遲線長度、空隙長度以及波長利用率，並利用了效用函數和乏晰邏輯系統的結合來改進光群集交換網路中的資料吞吐量。除此之外，由於傳輸服務品質(Quality of Service)也是光群集交換網路中所注重的議題，我們所提出的乏晰波長分配演算法也能夠在不同的訊務種類中支援傳輸服務品質。

Optical Burst Switching (OBS) is a promising technology that exploits the benefits of optical communication and supports statistical multiplexing of data traffic at a fine granularity making it a suitable technology for the all optical network. The characteristic of the OBS is using the control bursts (CBs) and the offset time mechanism to make bandwidth reservations without ACKs. Although the characteristic of OBS can help improve utilization, contention among the data bursts (DBs) that arrive simultaneously at a core node leads to burst loss and low throughput. Development of efficient algorithms for wavelength assignment is crucial to utilize wavelengths more efficiently so that we can improve the throughput in OBS networks. In this paper, we will propose the utility-based fuzzy wavelength assignment (UFWA) to improve the throughput in the OBS network by introducing the four factors, including preemption index, the used length of the FDL, void, and utilization and using the combination of the utility function and the fuzzy logic system. Moreover, the proposed UFWA can support quality-of-Service (QoS) between different traffic types, while the QoS is also the main issue in the OBS network.