@article{rouskas_bandikatla_2022, title={Recursive first fit: a highly parallel optimal solution to spectrum allocation}, volume={14}, ISSN={["1943-0639"]}, url={https://doi.org/10.1364/JOCN.445492}, DOI={10.1364/JOCN.445492}, abstractNote={We revisit the classical spectrum allocation (SA) problem, a fundamental subproblem in optical network design, and make three contributions. First, we show how some SA problem instances may be decomposed into smaller instances that may be solved independently without loss of optimality. Second, we prove an optimality property of the well-known first-fit (FF) heuristic. Finally, we leverage this property to develop a recursive and parallel algorithm that applies the FF heuristic to find an optimal solution efficiently. This recursive FF algorithm is highly scalable because of two unique properties: (1) it completely sidesteps the symmetry inherent in SA and hence drastically reduces the solution space compared to typical integer linear programming formulations, and (2) the solution space can be naturally decomposed in non-overlapping subtrees that may be explored in parallel almost independently of each other, resulting in faster than linear speedup.}, number={3}, journal={JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING}, author={Rouskas, George N. and Bandikatla, Chaitanya}, year={2022}, month={Mar}, pages={165–176} }
 @article{rouskas_bandikatla_2021, title={Parameterized Exhaustive Routing with First Fit for RSA Problem Variants}, ISSN={["2576-6813"]}, DOI={10.1109/GLOBECOM46510.2021.9685126}, abstractNote={We present a new single-step solution approach for the routing and spectrum allocation (RSA) problem that integrates the first-fit (FF) heuristic with a new routing strategy that we refer to as “parameterized exhaustive routing.” Our approach is to explore the whole routing space for a subset of the traffic requests, e.g., those with the largest demands or those of higher priority or importance. For each of the remaining requests we employ a greedy heuristic to select one of the candidate paths jointly with spectrum allocation. Our solution represents a two-parameter family of algorithms that bridges the gap between an exhaustive search of the routing space and current two-step methodologies for the RSA problem that select paths for each traffic request in isolation. The parameter values may be used to trade off the quality of the final solution and the computational requirements. Our results indicate that exploring the joint routing space of even a few large requests leads to better solutions than purely greedy approaches.}, journal={2021 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM)}, author={Rouskas, George N. and Bandikatla, Chaitanya}, year={2021} }