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

This thesis considers a joint beamforming design problem in the multicell multicast system with multiple groups that provide different multicast services using the same time-frequency resource. By jointly design beamforming vectors among cooperative cells, the worst received signal-to-interference-plus-noise-ratio (SINR) of all serving users in the multiple multicast groups can be improved. Inspired by previous works in the literature, we apply semidefinite relaxation (SDR) technique to perform joint beamforming design among the cooperating base stations. Per-cell power constraints are considered which makes solving the problem challenging. We propose two algorithms to accommodate the per-cell power constraints while performing joint beamforming. Simulation results show that the proposed algorithms provide better performance compared to the existing multicast methods in the multicell environment.1 Introduction 1 2 System Model and Problem Formulations 5 2.1 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Problem Formulations . . . . . . . . . . . . . . . . . . . . . . 7 3 Proposed Algorithm 9 3.1 Semidefinite Relaxation-Based Algorithm . . . . . . . . . . . . 9 3.2 Gaussian Randomization Method . . . . . . . . . . . . . . . . 13 3.3 Special Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4 Approximation Improvement 22 5 Simulation Results 27 6 Conclusions 3