Heterogeneous cloud radio access networks (H-CRANs), which take a separation of the remote radio units (RRHs) from the baseband units (BBUs), is considered to be a promising architecture for the future network due to its competitive advantages in both spectral efficiency and energy efficiency (EE). The RRH is mainly used to provide high data rate for mobile users (MTs) with high quality of service (QoS) requirements, while the evolved Node B (eNB) is deployed to guarantee the seamless coverage. To further enhance these benefits, in this paper, energy efficient uplink communications are investigated for H-CRANs with user cooperation and QoS guarantees. We formulate a joint optimization problem of relay selection, power allocation and network selection to maximize the EE of MTs with high QoS requirements. The optimization problem is a mixed-integer non-linear non-convex program and solved by Dinkelbach method and dual decomposition method. Moreover, a relay region selection algorithm is applied to reduce the computational complexity at the beginning of the optimization process. Numerical results show that the proposed scheme has improvement on the EE as compared with the scheme that joint power allocation and network selection and the scheme that joint relay selection and power allocation in H-CRANs.
['Yuan Zhang', 'Ying Wang', 'Weidong Zhang']
Energy efficient resource allocation for heterogeneous cloud radio access networks with user cooperation and QoS guarantees