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12:20 | On the Interference Cancellation by Reduced Channel Zero Forcing Class of Precodings in Massive MIMO Systems PRESENTER: Evgeny Bobrov ABSTRACT. In this research, we study the interference cancellation capabilities of receivers and transmitters in multiple-input-multiple-output (MIMO) systems using theoretical calculations and numerical simulations in Quadriga. We study so-called Reduced Channel Zero-Forcing (RCZF) class of precoding as well as Minimum MSE Interference Rejection Combiner (MMSE-IRC) and QR Maximum Likelihood Detection (QR-MLD) receivers. The precodings from the RCZF class are widely used in practice and include for example Zero-Forcing (ZF), Regularized Zero-Forcing (RZF) and Iteratively Weighted MMSE precodings. Our theoretical and experimental results confirm that MMSE-IRC and QR-MLD receivers in combination with the RCZF precoding provide complete interference suppression asymptotically. |

12:40 | Spectrum Allocation in Optical Networks: DSatur Coloring and Upper Bounds ABSTRACT. Routing and Spectrum Allocation (RSA) is one of the central problems in modern optical networks. In this setting, also called Flexible Grid, we want to find paths and allocate non-overlapping frequency slots for as many demands as possible. As opposed to the Routing and Wavelength Assignment (RWA) problem, where all frequency slots are of the same width, demands in Flexible Grids may require slots of different sizes, what makes the original NP-hard problem even more challenging. In this paper, we consider Spectrum Allocation (when routing is known), develop an efficient greedy algorithm based on "degree of saturation"-coloring, and by means of Constraint Programming, we show that the greedy algorithm is almost optimal even for hard real-world instances. |

13:00 | The VNS algorithm for the periodic pick-up and delivery helicopter routing problem in oil and gas offshore projects ABSTRACT. In offshore field development projects, the high operating costs is a crucial part of the total expenses. In this paper, we consider the helicopter routing problem in a given time horizon. We need to deliver workers at the offshore platforms every day and return other workers to depot. We have a fleet of identical helicopters with known capacity. All routes start and finish at the depot, the length of each route cannot exceed a given threshold. We can split the demand for each platform and visit it by some helicopters. Our goal is to find the routes to satisfy all demands with minimal total travel length. To tackle this pick-up and delivery routing problem, we design the MILP model and adopt the VNS-algorithm. Some hard constraints are relaxed and included into the objective function with penalties. Computational results for the real world test instances of the JV Vietsovpetro company are discussed. |

13:15 | Differential Evolution for Short Wave Antenna Array Optimization ABSTRACT. In this paper, we develop and study experimentally a differential evolution algorithm for a non-convex constrained quadratic programming problem, which has an application in radiophysics. In this application, it is required to maximize the directed radiation in short wave range, using a phased antenna array. The differential evolution method is adapted to the specifics of the problem under consideration. In the computational experiments, the proposed algorithm is compared to the gradient ascend method and BARON package, which is based on the branch and bound approach. A parallel implementation of the proposed algorithm on the GPU is described and experimaentally tested. |