Fairness-oriented Optimization for SWIPT-enabled multigroup multicasting systems

Abstract

This paper examines a multigroup (MG) multicast (MC) precoding system consisting of heterogenous types of users, viz., energy harvesting (EH) explicit and/or information decoding (ID) only and/or EH as well as ID operations concurrently. These users, present in the MG-MC configuration, require simultaneous wireless information and power transfer (SWIPT), which is facilitated via optimal precoding. The objective is to use separate precoders to deal with different MC groups of ID users and contribute wireless power to a single (last) group of EH users through dedicated energy precoder(s). The proposed system is designed to optimize transmit power, spectral efficiency and harvested energy which enables its performance assessment from different outlooks. Correspondingly, the present work involves formulation of precoder design problems to optimize sum-transmit power, sum-spectral efficiency, and sum-harvested energy from a general system investigation viewpoint, respectively, comparing them with their analogous fairness problems addressing minimization of maximum transmit power from each precoder, maximization of minimum spectral efficiency for every applicable ID user, and maximization of minimum harvested energy for every concerned EH user. All the precedingly mentioned problems are addressed under constraints that include a non-linear minimum energy harvesting threshold, a total transmit power ceiling, and a required minimum spectral efficiency. The aforementioned problems are solved by appropriate transformations followed by the use of evident iterative algorithms involving semi-definite relaxation (SDR) and slack-variable replacement (SVR) processes. The present work contains a comprehensive simulation comparing the proposed sum-metrics and their analogous fairness models by varying different parameters and conditions. © 2025 Elsevier B.V.