Multiuser Full-Duplex Relaying: Enabling Dual Connectivity via Impairments-Aware Successive Interference Cancellation

In this article, we consider the downlink of a cellular communication network, where dual-connectivity at the end-users is enabled with the assistance of a full-duplex (FD) massive-multiple-input-multiple-output (mMIMO) relay. In particular, the base station transmits separate data streams through the cochannel direct link as well as the FD relay channel, utilizing the successive-interference-cancellation (SuIC) capability at the receiver. As a result, the downlink communication data can be interchangeably loaded to separate subcarriers, employing an orthogonal multicarrier strategy, or to different available links, i.e., direct or FD relay link, employing the nonorthogonal SuIC at the receiver. In order to reliably model the SuIC operation at the receiver, the collective sources of impairments, including the nonlinear transmit and receiver chain distortions as well as the channel state information inaccuracy are incorporated. An optimization problem for joint subcarrier and power allocation is then devised in order to maximize system sum-rate, which belongs to the class of smooth difference-of-convex problems. An iterative optimization solution is then proposed, utilizing successive inner approximation framework, which converges to the point that satisfies Karush–Kuhn–Tucker optimality conditions. Numerical results show performance and robustness gain of proposed SuIC scheme in terms of sum-rate compared to previously proposed single-connectivity and half-duplex relaying schemes.