Energy-efficient mobile association in device-to-device-enabled heterogeneous networks

In this paper, we investigate energy-efficient mobile association for users with the capability of device-to-device (D2D) communications in heterogeneous networks. To maximize the energy efficiency (EE) of uplink transmission while guaranteeing the quality-of-service requirement of users, we first propose a brute-force-based mobile association algorithm, which requires complete channel state information and searches all association candidates. To reduce the cost involved in computation, channel estimation, and feedback, we also develop a distance-based mobile association (DMA) algorithm, which operates according to geographical information of access points and D2D relay nodes and with much lower computational complexity. Simulation results demonstrate that the proposed DMA algorithm can achieve a good tradeoff between the EE and complexity.