Topological Rate-Splitting Based Power Allocation Scheme in K-cell MISO Interference Channel with Imperfect CSIT

Abstract

To tackle inevitable effects of imperfect channel state information (CSI), an achievable scheme, known as rate-splitting (RS), has been proposed recently. Focusing on the general K-user multiple-input-single-output (MISO) interference channel (IC) with an arbitrary CSI at transmitter (CSIT) quality of each interfering link, the topological RS (TRS) scheme obtains the degrees-of-freedom (DoF) gain by a multilayer structure and transmitting multiple common messages to be decoded by some groups of users rather than all users. In this paper, we investigate TRS scheme from the point of view of sum rate. Specifically, we formulate a power allocation problem as an optimization problem to maximize the sum rate of all users with a sequence of successive interference cancelation (SIC) decoding order constraints. Then, we convert this problem into a difference of convex program (DCP), and approximate it by its first-order Taylor expansion around a feasible point. Numerical results demonstrate the performance gain of the proposed scheme.