On the spectral efficiency of full-duplex small cell wireless systems

We investigate the spectral efficiency of full-duplex small cell wireless\nsystems, in which a full-duplex capable base station (BS) is designed to\nsend/receive data to/from multiple halfduplex users on the same system\nresources. The major hurdle for designing such systems is due to the\nself-interference at the BS and co-channel interference among users. Hence, we\nconsider a joint beamformer design to maximize the spectral efficiency subject\nto certain power constraints. The design problem is first formulated as a\nrank-constrained optimization one, and the rank relaxation method is then\napplied. However the relaxed problem is still nonconvex, and thus optimal\nsolutions are hard to find. Herein, we propose two provably convergent\nalgorithms to obtain suboptimal solutions. Based on the concept of the\ndifference of convex functions programming, we approximate the design problem\nby a determinant maximization program in each iteration of the first algorithm.\nThe second method is built upon the sequential parametric convex approximation\nmethod, which allows us to transform the relaxed problem into a semidefinite\nprogram in each iteration. Extensive numerical experiments under small cell\nsetups illustrate that the full-duplex system with the proposed algorithms can\nachieve a large gain over the half-duplex one.\n