Study On The Flexible Grid Optical Network With A Multi-carrier Light Source

Recently, the Internet traffic grows rapidly with the rise of high-definition video, IPTV, cloud computing and other Internet applications. The traditional WDM transmissionsystem is an important solution to satisfy the growing traffic. Because of the fixed andcoarse-granularity wavelength allocation, traditional WDM transmission system canonly provide fixed bandwidth service and result in inefficiency of optical spectrum. Theavailable spectrum of fiber is approaching its limits. New Applications require a flexibledata rate, high capacity and spectrum-efficienct optical transmission system.Flexible grid optical network can solve the above problems. It can assign opticalspectrum resource in fine granularity to avoid the waste of spectrum resource. It canassign different numbers of continued optical carriers to different lightpaths on demand.In this way, flexible grid optical network can support various lightpaths with differentdate rates.The thesis mainly improves the traditional ROADM networks and proposes theC-MCLS based optical drop-add-drop network which supports flexible allocation ofspectrum resource. This thesis also proposed a flexible spectrum allocation algorithmswhich is called the Minimum Fragmentation Request First algorithm.The advantage of proposed network is that the carriers generated by the C-MCLSwere dropped by ROADMs as light source to replace the distributed LDs, and networkcost and management complexity are decreased in this way. Because the proposednetwork is a flexible network and it can support flexible spectrum allocation, it is morespectrum-efficienct.The conclusion of the thesis is as follows: firstly, theoretical analysis is performedto evaluate the network performance in terms of the lightpath blocking probability(LP_BP) and the effective spectral efficiency. Then, simulations are carried out tocompare the traditional ROADM network and proposed network and how channelspacing and guard band impact on the proposed network are also studied. Thesimulation result shows that the proposed network achieves lower optical LP_BP andhigher effective spectral efficiency than traditional ROADM network under the samenetwork load condition. Secondly, the paper also compares the proposed spectrumallocation algorithm with two other algorithms, and the simulation results show that theMinimum Fragmentation Request First has the most balanced performance. The optimal channel spacing evaluations show that narrow channel spacings such as6.25and12.5GHz greatly improve LP_BP performance when low bit-rate traffic requestsdominate in the traffic model. And, as the number of high bit-rate traffic requestsincrease, the performance advantage of narrow channel spacing is graduallydisappearing.