Enhancing C-RAN Downlink Performance via Inter-UE D2D Cooperation

Cloud radio access network (C-RAN) is an emerging architecture for achieving high data rate and massive connectivity in future wireless communication systems. To further improve the performance of C-RAN downlink, this work considers the advantages of cooperation among user equipments (UEs). Specifically, it is assumed that the UEs can exchange the downlink received baseband signals via device-to-device (D2D) communication links which are orthogonal to downlink channel. The problem of jointly optimizing the C-RAN downlink and inter-UeD2d communication strategies is tackled with the goal of maximizing the sum-rate of UEs. To address the formulated problem, an iterative algorithm is proposed which attains a suboptimal solution of the problem. Numerical results confirm that the inter-UE D2D cooperation is effective to improve the downlink performance of C-RAN systems.