Analysis of quality-of-service aware orthogonal frequency division multiple access system considering energy efficiency

The increasing demand of high-speed and secure wireless broadband networks has generated significant interests in the optimisation and the analysis of energy-efficiency in orthogonal frequency division multiple access (OFDMA) system. In this study, the authors present an in-depth mathematical analysis of the maximisation of energy-efficiency by taking into consideration the quality of service (QoS). By using optimality conditions, they have shown that the optimal solutions can be obtained analytically. Furthermore, it has been proved in this study that this optimisation problem is strictly concave with the existence of a global maximum. Case studies with multiple subchannels validate the consistency of numerical results with the results obtained from derivative-free method like genetic algorithm. Graphical illustrations also validate and confirm the numerical values obtained from the mathematical analysis. Therefore the solution is optimal with respect to the OFDMA model adopted in this study. The authors proposed approach can be used for practical applications because of its simplicity and efficacy with QoS guaranteed for efficient energy consumption.