Length-Threshold-based Placement and Assignment of Virtualized Elastic Regenerator in Distance-Adaptive Translucent Elastic Optical Networks

  • 高 豪辰

Student thesis: Master's Thesis


With growing development of technology requirements on network traffic have become insatiable Providing an efficient network environment is an important issue in the development of Internet and optical networks also play an important role in it In Wavelength-Division Multiplexing (WDM) optical networks a wavelength is a basic transmission unit However this kind of rigid granular resource allocation architecture is liable to worsen the spectrum efficiency With improving techniques Optical Orthogonal Frequency-Division Multiplexing (O-OFDM) has make the wavelength carriers possible to partially overlap with each other Thus it has promoted the innovation of Elastic Optical Networks (EON) In EON the allocation unit is transferred to Frequency Slot (FS) with smaller granularity transmission demands can flexibly assign the corresponding number of FSs according to the required bandwidth Therefore we can not only raise the spectrum efficiency but allocate the spectrum resources more efficiently In distance adaptive EON routing modulation format and spectrum assignment (RMSA) is the main issue to be solved Appropriately choosing a routing path and trying to select a higher-level modulation format the spectrum resources can be assigned efficiently Thus other requests can have more opportunities to be served Since there is maximum transmission distance (MTD) constraints if the transmission distance of requests is too long the transport may be failed caused by the optical reach (OR) Besides virtualized elastic regenerators (VERs) can be assigned to regenerate transmission and the one be regenerated can be transmitted to a farther destination Therefore the requests are not such easy to be blocked In addition VERs can re-modulate and convert spectrum which improve the spectrum efficiency However due to cost control placing VERs strategically on topology has become an important issue This kind of limited VERs network structure is the so called translucent optical networks In related researches of translucent EONs VERs assignment strategies is another considerable issue In previous studies they designed VER placement and assignment strategies without considering transmission distances and modulation formats The VER placed nodes were worse and it did not consider about assignment strategies with placements either Thus though VERs are used spectrum efficiency is not much improved We proposed two VER placement and one assignment strategies to solve this problem Our strategies tend to place VERs on the nodes in longer transmission segments It enables the segments to consume fewer FSs improves the overall spectrum efficiency and allows more requests to be successfully served In simulation results our proposed TLTP gets a considerable improvement in the performance of bandwidth blocking probability (BBP) In addition we also found that VER assignment are less important than placement Even if the assignment is not the most effective one if VERs are placed to right positions the overall BBP will also improve
Date of Award2018 Aug 21
Original languageEnglish
SupervisorChing-Fang Hsu (Supervisor)

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