Joint Clustering and Power Allocation in Coordinated Multipoint Assisted C-NOMA Cellular Networks

Abstract

We consider a wireless network consisting of two adjacent cells, where the joint transmission (JT) coordinated multipoint (CoMP) is established to assist the user equipments (UEs) located at the edge of each cell. In addition, full-duplex (FD) cooperative non-orthogonal-multiple-access (C-NOMA) is invoked within each cell to improve the data rates of the UEs and to assist those at the cell edge. The UEs are categorized into two groups, namely, cell-center UEs (<inline-formula> <tex-math notation="LaTeX">$CUs$ </tex-math></inline-formula>) and cell-edge UEs (<inline-formula> <tex-math notation="LaTeX">$EUs$ </tex-math></inline-formula>). The <inline-formula> <tex-math notation="LaTeX">$CUs$ </tex-math></inline-formula> are the UEs located around the center of each cell. Meanwhile, the <inline-formula> <tex-math notation="LaTeX">$EUs$ </tex-math></inline-formula> are the UEs located at the edge of each cell, where the JT-CoMP is applied since they have less distinctive received power from two cells. In this paper, a framework to jointly optimize the power control and the UEs clustering of CoMP-assisted FD C-NOMA system is formulated as an optimization problem to maximize the network sum-rate while guaranteeing the required quality-of-service of UEs. The formulated problem is a non-convex mixed-integer non-linear program that cannot be solved in a straightforward manner. To tackle this issue, the formulated problem is decomposed into an inner power allocation problem and an outer UEs clustering problem. For the inner problem, a computational-efficient solution is obtained. Meanwhile, the outer problem is reformulated as a one-to-one three-sided matching game. Then, a low-complexity near-optimal clustering algorithm is proposed. The simulation results demonstrate that 1) the optimality of the power control solution; 2) the CoMP-assisted FD C-NOMA has a superior performance compared to CoMP-assisted half-duplex (HD) C-NOMA and CoMP NOMA schemes for moderate values of self-interference. It has been also shown that the proposed solution achieves around 96.5&#x0025; of the average achievable network sum-rate of the optimal solution.