With the widespread application of wireless networks and the requirements of different user equipments (UEs), energy has become a scarcer resource as well as spectrum. In this paper, considering the actual scenarios of imperfect channel state information (CSI), we study a resource allocation scheme in the downlink orthogonal frequency division multiple access (OFDMA) systems. To balance between energy efficiency (EE) and proportional fairness (PF), the problem is formulated as maximizing average achievable EE with the constraints of PF of users and QoS assurance. To solve the optimal problem, we divide it into two layers. The sub-problem P1 of inner layer is solved to maximize PF, with the parameter of total transmit power which is updated by the sub-problem P2 of outer layer. In outer layer, with the allocation scheme from P1, a gradient-based adaptation resource allocation algorithm is proposed to achieve the maximum EE with total transmit power updated in every gradient iteration. Moreover, the impacts of the imperfect CSI on EE and PF are analysed. Simulation results are presented to show the superior performance of the proposed algorithms and verify the analytical findings.
['Jing Wang', 'Yan Zhang', 'Hui Hui', 'Ningbo Zhang']
QoS-aware proportional fair energy-efficient resource allocation with imperfect CSI in downlink OFDMA systems