A Study Of Mixed-Line-Rates Based Spectrum Allocation Technology In Elastic Optical Networks

With the rapid development of high-bandwidth services such as next-generation mobile communication technology and high-definition video,the network traffic volume shows explosive growth,which puts forward higher requirements for the traffic volume of network.Due to the benefit of high speed and large capacity,optical network becomes the main infrastructure supporting network data communication.At the same time,with the gradual upgrading of line rate in optical network,multiple line rate signals coexist in network,forming a mixed line rate(MLR)optical network.Compared with the traditional wavelength division multiplexing(WDM)optical network,elastic optical networks(EONs)employ finer frequency spacing and allocate the matched spectrum resources for the service requests according to their bandwidth requirements.Thus,EONs provide a more flexible resource allocation technology for MLR transmission and undoubtedly become the main trend of future optical network development.In the process of optical signal transmission,physical layer impairments(PLIs)seriously affect the quality of transmission(QoT)for service requests,especially in MLR optical networks.In this context,from the perspective of the linear and the non-linear PLIs,the spectrum allocation technology of EON for MLR is mainly studied in this paper in order to guarantee the QoT of service requests,reduce network blocking probability and improve network traffic volume.The main research achievements are as following:(1)From the perspective of the linear PLIs,this paper has proposed a highest-modulation-first last-fit spectrum allocation algorithm in EON.Considering both chromaticity dispersion and polarization mode dispersion,this algorithm constructs the maximum transmission reach model for optical signal under dispersion constraint.Furthermore,according to the requirement of transparent distance between source and destination nodes,the highest-level modulation format is adaptively provided for service requests,and the spectrum allocation is completed with the second criterion of spectrum slot position as high as possible.In this case of spectrum allocation,this algorithm not only meets the requirements of QoT for service requests,but also reduces the spectrum resource consumption of service requests,improving the spectrum resources utilization in EONs.(2)From the perspective of the non-linear PLIs,this paper has proposed a holding-time-aware shared spectrum partitioning spectrum allocation algorithm in EONs for MLR.Considering the differences on modulation format for different line rates,this algorithm constructs some Q-value models under cross-phase modulation constraint.Furthermore,in order to increase the interval between service requests with different line rates,according to the holding-time requirements of service requests,entire spectrum resources of each link are divided into some exclusive and shared zones to provide a holding-time-aware spectrum allocation for different line-rates in EONs.In this case of spectrum allocation,this algorithm not only improves the spectrum resources utilization in EONs from perspective of time domain,but also improves the QoT of service requests.