Precoding and Selection for Coordinated Multipoint Transmission in Fronthaul-Constrained Cloud-RAN

A joint transmission point selection and precoding scheme is proposed herein to mitigate interference in a C-RAN system with distributed fronthaul-constrained transmission points. Two methods are proposed to deal with the original NP-hard problem. First, reformulation into convex form is done using an upper bound method, where tightness of the bound and its implication on system scenario are easy to establish. The second one uses successive convex approximation to approximate the nonconvex constraint and is shown to maximize spectral efficiency at the expense of higher computational complexity compared to the first approach. Numerical results will show the efficacy of the proposed approaches.