Joint Uplink-Downlink Resource Allocation for D2D Underlaying Cellular Network

Device-to-device (D2D) communication is an emerging 5G technology to improve spectrum efficiency and reduce data traffic load in wireless networks. In this paper, a joint uplink-downlink resource allocation (JUDRA) approach is presented to maximize the network throughput while guaranteeing the quality of service (QoS) for both cellular users (CUs) and D2D users (DUs). In particular, the proposed JUDRA approach allows DUs to reuse either uplink or downlink CUs' resources. Besides, an optimization problem is formulated as a mixed-integer nonlinear programming problem (MINLP) which is generally NP-hard. The problem is solved in two stages: sub-channel (SC) assignment stage and power allocation stage by utilizing the characteristics of sequential geometric programming. Moreover, a low computational complexity approach is suggested that converges to the near-optimal solution in polynomial time. Finally, comparative results are presented to validate the effectiveness of the proposed approach.