Intelligent Block-Level Interference Exploitation Beamforming Design: An ADMM Approach

We study constructive interference based block-level beamforming (CI-BLB) in the downlink of multi-user multiple-input single-output (MU-MISO) systems. CI-BLB achieves im-proved performance over the traditional CI-based symbol-level beamforming (CI-SLB) method, because of its more intelligent power allocation scheme over the considered block of symbol slots. In this paper, we design a low-complexity algorithm based on the alternating direction method of multipliers (ADMM) framework, which can efficiently solve QP problems. We analyze the convergence and complexity of the proposed algorithm. Nu-merical results validate the optimality of the proposed algorithm, and further show that the proposed algorithm offers a flexible performance-complexity tradeoff by limiting the maximum num-ber of iterations, which motivates the use of CI - BLB in practical wireless systems.