Optimal Power Allocation for OFDMA Systems under I/Q Imbalance

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Abstract

A direct-conversion architecture can offer highly integrated low-cost hardware solutions to communication transceivers. However, it has been demonstrated that radiofrequency impairments, such as amplifier nonlinearities, phase noise, and in-phase/quadrature-phase imbalances (IQI), can lead to a severe degradation in the performance and fairness. To this end, we study the power allocation (PA) problem in an orthogonal frequency-division multiple access systems, when the served user equipment (UE) suffers from different levels of IQI. Additionally, we present a novel low-complexity solution with directly calculated PA policies, given the Lagrange multiplier, which mitigates the impact of IQI and achieves fairness in terms of capacity for the served UE, by maximizing the minimum achievable capacity of the UE. The effectiveness of the offered solution is validated through simulation results, which reveal that it can drastically increase the minimum achievable UE’s capacity.