Energy-Efficient and QoS-ware Resource Allocation for Relay-enhanced OFDMA Wireless Cellular Networks

We focus on energy-efficient resource allocation with quality of service (QoS) guarantee for orthogonal frequency division multiple access (OFDMA) based wireless cellular networks with decode-andforward (DF) relaying. The joint transmission mode selection, subcarrier allocation and power control for the energy efficiency (EE) maximization problem is formulated as a non-convex and combinatorial optimization problem with the consideration of both the transmit and circuit power consumption, QoS requirements of mobile stations (MSs), as well as individual power constraints at base station (BS) and relay stations (RSs). To solve the global optimization problem, a low-complexity transmission mode selection and subcarrier allocation algorithm is performed firstly. By exploiting the properties of relaying transmission and nonlinear fractional programming, an iterative power control algorithm is devised to optimize the power allocation of BS and RSs subsequently. Numerical results demonstrate that the proposed algorithm achieves significant EE improvement compared with the conventional spectral-efficient design and the energy-efficient design without the assistance of relaying transmission. Key-Words: radio resource allocation, QoS, energy efficiency, relaying, subcarrier allocation, power control