Joint Beamforming for Multicell Multigroup Multicast with Per-cell Power Constraints

Abstract

This paper considers a joint beamforming design problem in the multicast broadcast single frequency network (MBSFN) scenario with multiple multicast groups that provide different multicast services. To solve the joint beamforming design among the cooperating base stations, which is also known as the joint processing scheme in the coordinated multipoint transmission (CoMP) defined in the long-term evolution-advanced (LTE-A) system, we devise different optimization techniques, such as semidefinite relaxation, fractional programming, and difference of convex (DC) programming. In this paper, per-cell power constraints are considered. In addition, we consider the design of higher rank transmission to increase the spectrum efficiency and the design of robust beamforming to alleviate performance degradation caused by imperfect channel state information. In the simulation results, we demonstrate the potential of the proposed algorithms in terms of the maximized minimum signal-to-interference plus noise ratio (SINR), and compare the proposed methods with the traditional MBSFN transmission scheme and the existing noncooperating multicast beamforming methods. The results show that the proposed methods, indeed, provide better performance. To complete the discussion, we also provide numerical results for the robust and nonrobust beamforming schemes in terms of the power consumption, feasibility ratio, and the histogram of the normalized SINR.