Energy-Efficient Resource Allocation in Uplink OFDMA Systems under QoS Constraints

Uplink energy-efficient communication is an important issue due to the limited battery capacity of user equipments (UEs). In this paper, we study the energy-efficient resource allocation for uplink OFDMA systems. We propose efficient suboptimal resource allocation algorithms to maximize system energy efficiency (EE) under individual UEs´ transmit power and quality of service (QoS) constraints. The proposed algorithms consist of two iterative resource allocation stages: the rate achievement stage and the EE maximization stage. In the rate achievement stage, resources are assigned to meet the users´ QoS constraints and, in the EE maximization stage, the overall system EE is maximized using residual resources. Simulation results show that the proposed algorithms increase the system EE as well as the system throughput, compared with existing algorithms.