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This paper considers the online routing, modulation, spectrum, and core allocation problem in elastic optical networks. Three algorithms are proposed to minimize the bandwidth blocking probability while taking into account the impact of interference from established lightpaths. These algorithms are based on a sequence of alternative paths, ordered in terms of increasing lengths, determined by Yen's algorithm. Each of the algorithms for the selected single or dual lightpath enforces the constraints of spectrum continuity, contiguity of the slots, and non-overlapping of the spectra with the established lightpaths, maximizes the number of bits per symbol, and selects a specific core on each link of the path. Simulation studies performed for two sample networks showed that the crosstalk has a significant impact on the bandwidth blocking probability. The best results were obtained by iterating over all paths and all slots, selecting the lightpath with the lowest average crosstalk per slot, consisting of the most loaded cores. [ABSTRACT FROM AUTHOR]

Service time-varying traffic flexible optical networks require a dynamic bandwidth allocation in order to follow the source transmission rate. The problem of service time-varying traffic, assuming that the set of connection requests is not known in advance, is considered in this work. Connection requests arrive randomly and have random durations. The considered dynamic RSA problem involves minimizing the probability of future connections blocking while maintaining spectrum continuity constraints and non-overlapping spectrum assignment constraints between spectrum-adjacent connections on the network links. The proposed algorithm determines the path with the required number of slots around the reference frequency for a connection request. An analysis of the network with time-varying traffic on the network connections was carried out on the basis of spectrum expansion/contraction schemes which allow to determine average blocking probability of the additional slot requests on these connections. The obtained results have been compared with those obtained by a well known algorithm that solves the dynamic RSA problem. [ABSTRACT FROM AUTHOR]