软件定义灵活光网络中物理层损伤感知的路由和频谱分配算法研究

发布时间：2018-08-12 11:27

【摘要】：随着光网络中宽带业务的急剧增长,如高清视频、数据中心、互动游戏、云计算等业务,导致对光网络的带宽需求不断增加。这种不断增长的带宽需求对光网络的发展和扩容带来了严峻的挑战,并且仅仅通过对光网络传输容量的增加已不能实现光网络中的频谱高效率利用。已有的波分复用(Wavelength Division Multiplexing,WDM)光传送网络的频谱被划分成固定带宽宽度,如50GHz或100GHz,每个带宽宽度代表一条光通路,并且每一个带宽宽度的中心和频谱大小固定,这种固定的光通路划分方式容易导致频谱带宽的浪费。并且因此,光网络需要向着支持多速率业务共存且支持高效的频谱灵活分配方向发展。随着正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)的发展,光网络可以对频谱资源进行更细粒度的划分(如12.5GHz、6.25GHz或更小),可以按照业务请求的频谱大小为其分配频谱资源。同时,随着软件定义的概念引入到光网络中,光网络正向着灵活、可编程、智能的方向发展。因此,下一代光网络逐渐向着软件定义灵活光网络方向发展。随着光网络中混合速率业务的出现,不同速率的信号可以同时在同一根光纤中传输,不同调制格式下的相邻信道之间会产生严重的物理损伤,尤其是交叉相位调制(Cross-Phase Modulation,XPM)。光网络中的光信号受到物理层损伤的影响传输质量(Transmission of Quality,Qo T)无法得到保证。物理层损伤的影响程度与不同信号的传输速率以及不同速率信号之间的频谱间隔密切相关,这使得软件定义灵活光网络中多速率共存的效率受到了严重的限制。同时,随着频谱更细粒度的划分,频谱连续性约束和频谱一致性约束在频谱分配过程中变的更为严格。本论文在该背景下,深入研究了软件定义灵活光网络中物理层损伤感知的路由和频谱分配(Impairments Aware Routing and Spectrum Assignment,IRSA)问题,以保证业务的传输质量,提升了网络的性能。主要研究成果如下:(1)基于灵活光网络背景,提出了一种频谱分区-拓扑分层的IRSA算法。该算法考虑在多速率共存的灵活光网络下较为严重的XPM损伤,提出了频谱分区的策略。通过加大不同速率光信道间的物理距离,从而降低XPM影响。在此基础上,通过将网络拓扑抽象成多个子拓扑,很好的解决了频谱一致性约束和频谱连续性约束对频谱分配的限制。所提算法既能解决频谱一致性和频谱连续性限制,也满足了业务的Qo T的需求,降低了业务阻塞率。(2)针对软件定义灵活光网络中交叉相位调制损伤感知的路由和频谱分配问题,提出了基于Open Flow的低信道间影响的路由和频谱分配算法。通过在软件定义灵活光网络Open Flow控制器中添加频谱分区模块及扩展Open Flow协议,将光网络中不同速率的业务分配到不同的频谱区域,加大低速率业务和高速率业务之间的信道间隔,以降低交叉相位调制损伤并提高资源利用率。
[Abstract]:With the rapid growth of broadband services in optical networks, such as high-definition video, data centers, interactive games, cloud computing and other services, resulting in an increasing demand for optical network bandwidth. This growing bandwidth demand poses a severe challenge to the development and expansion of optical networks, and the efficient use of spectrum in optical networks can no longer be achieved only by increasing the transmission capacity of optical networks. The spectrum of an existing WDM (Wavelength Division multiplexing optical transport network is divided into fixed bandwidth widths, such as 50GHz or 100GHz, each bandwidth width representing an optical path, and the center and spectrum size of each bandwidth width fixed. This fixed optical path division method can easily lead to a waste of spectrum bandwidth. Therefore, optical networks need to support multi-rate traffic coexistence and efficient spectrum allocation. With the development of orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division), optical networks can partition spectrum resources more granularly (for example, 12.5 GHz or less), and allocate spectrum resources according to the spectrum size of traffic request. At the same time, with the introduction of the concept of software definition into optical networks, optical networks are becoming flexible, programmable and intelligent. Therefore, the next generation optical network is gradually developing towards flexible optical network defined by software. With the emergence of hybrid rate traffic in optical networks, signals at different rates can be transmitted in the same optical fiber at the same time, and serious physical damage will occur between adjacent channels in different modulation formats, especially Cross-Phase modulation. The optical signal in optical network is affected by the damage of physical layer. The quality of transmission (Transmission of quality can not be guaranteed. The degree of damage in physical layer is closely related to the transmission rate of different signals and the spectrum interval between different rate signals, which seriously limits the efficiency of multi-rate coexistence in flexible optical networks defined by software. At the same time, with the finer granularity of spectrum partition, spectrum continuity constraints and spectral consistency constraints become more stringent in the spectrum allocation process. In this paper, the problem of routing and spectrum allocation of damage sensing in the physical layer of flexible optical networks is studied in detail in order to ensure the transmission quality and improve the performance of the network. The main research results are as follows: (1) based on the background of flexible optical networks, a spectrum partition-topology hierarchical IRSA algorithm is proposed. This algorithm considers the serious XPM damage in flexible optical networks with multi-rate coexistence and proposes a strategy of spectrum partitioning. The influence of XPM is reduced by increasing the physical distance between optical channels at different rates. On this basis, by abstracting the network topology into multiple sub-topologies, the constraints of spectrum consistency constraints and spectral continuity constraints on spectrum allocation are well solved. The proposed algorithm can not only solve the limitation of spectrum consistency and spectrum continuity, but also satisfy the requirement of QoS, and reduce the traffic blocking rate. (2) the routing and spectrum allocation problems of damage sensing of cross-phase modulation in flexible optical networks are defined by software. A low channel impact routing and spectrum allocation algorithm based on Open Flow is proposed. By adding spectrum partitioning module and extending Open Flow protocol to the Open Flow controller of flexible optical network defined by software, the traffic of different rates in optical network is assigned to different spectrum regions. The channel spacing between low rate traffic and high rate traffic is increased to reduce cross-phase modulation damage and improve resource utilization.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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