Uplink Power Control for D2D-enabled HetNet with Partial CSI via Fractional Programming

Heterogeneous wireless networks (HetNets) are becoming an integral part of future generation networks, where the macro-cell base stations (MBSs), small cell base stations (SCBSs), and device-to-device (D2D) enabled links coexist together. Frequency reuse is employed to maximize capacity gains. However one major challenge is introducing the fundamental problem of interference management in the network caused by the sharing of the spectrum among the different tiers of the HetNet. Power control (PC) is one technique for interference management which can also be used to enhance the overall system efficiency. The objective of this paper is to study the problem of cross-tier interference management for underlay D2D users in a heterogeneous macro-small cell network assuming imperfect Channel State Information (CSI). The network consists of one macro-cell with a centered MBS and one small-cell cellular user equipment (SUE) linked to its SCBS. Fractional programming (FP) is used to solve the optimization problem of power allocation in the network to find the optimal power that maximizes the sum rate of D2D and small cellular users while guaranteeing a minimum quality of service (QoS) of the macro cellular user.