BER-Adaptive RMLSA Algorithm for Wide-Area Flexible Optical Networks

Abstract

Wide-area optical networks face significant transmission challenges due to the relentless growth of bandwidth demands experienced nowadays. Network operators must consider the relationship between modulation format and maximum reach for each connection request due to the accumulation of physical layer impairments in optical fiber links, to guarantee a minimum quality of service (QoS) and quality of transmission (QoT) to all connection requests. In this work, we present a BER-adaptive solution to solve the routing, modulation format, and spectrum assignment (RMLSA) problem for wide-area elastic optical networks. Our main goal is to maximize successful connection requests in wide-area networks while choosing modulation formats with the highest efficiency possible. Consequently, our technique uses an adaptive bit-error-rate (BER) threshold to achieve communication with the best QoT in the most efficient manner, using the strictest BER value and the modulation format with the smallest bandwidth possible. Additionally, the proposed algorithm relies on 3R regeneration devices to enable long-distances communications if transparent communication cannot be achieved. We assessed our method through simulations for various network conditions, such as the number of regenerators per node, traffic load per user, and BER threshold values. In a scenario without regenerators, the BER-Adaptive algorithm performs similarly to the most relaxed fixed BER threshold studied in blocking probability. However, it ensures a higher QoT to most of the connection requests. The proposed algorithm thrives with the use of regenerators, showing the best performance among the studied solutions, enabling long-distance communications with a high QoT and low blocking probability.

Improving the Performance of SDM-EON Through Demand Prioritization: A Comprehensive Analysis

“…The MAR was calculated considering a worst case scenario, fully-loaded C-band with 320 FSU slots occupied by signal with a bandwidth equal to one FSU. For more details about the optical reach calculation, the reader is referred to [20], Section III. In this work crosstalk between spatial modes was not considered.…”

“…In a multi-spectrally and spatially elastic optical network, this algorithm is known as the Routing, Modulation Level, Spatial mode, and Spectrum Assignment (RMLSSA) algorithm [16]- [19]. An RMLSSA algorithm is in charge of finding a path -an optical connection between two network nodes -to each network demand (routing), a modulation format that achieves a good trade-off between spectrum usage and optical reach (modulation level) [20], a specific fiber core (spatial mode) and a set of contiguous and continuous FSUs (spectrum) on the selected route and core.…”

Impact of Amplification and Regeneration Schemes on the Blocking Performance and Energy Consumption of Wide-Area Elastic Optical Networks

“…Thus, an RMLSA solution is better than another if it consistently exhibits a lower blocking ratio for different scenarios. In wide-area dynamic EON, there are two primary sources of blocking: a lack of capacity to establish connections and the inability to provide an acceptable quality-of-transmission (QoT) to the network connection, despite capacity availability [5], [7], [8], [9]. The former case arises when there are effectively no available slots to meet the requested bandwidth or having available slots these cannot be used due to spectrum fragmentation, which occurs when the available slots are isolated and are discontinuos along the optical path or are not contiguous on the spectrum domain [10], [11].…”

“…The latter case arises when the length of the route is such that the accumulation of physical layer impairments (PLI), such as amplified spontaneous emission (ASE) noise from optical amplifiers and nonlinear distortions from Kerr nonlinearity, degrade the signal-to-noise ratio (SNR) and thus, the biterror-rate (BER), beyond acceptable limits. As in [9], we term these types of blocking as capacity blocking and reach blocking, respectively.…”

“…Standard approaches to solve the RMLSA problem establish end-to-end all-optical communication (i.e., transparent) relying only on erbium-doped fiber amplifiers (ED-FAs) to compensate losses between source and destination nodes [5], [7], [8], [12], [13], [14], [15], [16]. In these cases, reach blocking has been the central problem in wide-area networks [5], [8], [7], [9]. This situation can be mitigated by increasing the maximum transmission reach of optical signals.…”