Power Minimizer Symbol-Level Precoding: A Closed-Form Sub-Optimal Solution

Abstract

In this letter, we study the optimal solution of the multiuser symbol-level precoding (SLP) for minimization of the total transmit power under given signal-to-interference-plus-noise ratio (SINR) constraints. Adopting the distance preserving constructive interference regions (DPCIR), we first derive a simplified reformulation of the problem. Then, we analyze the structure of the optimal solution using the Karush-Kuhn-Tucker (KKT) optimality conditions, thereby we obtain the necessary and sufficient condition under which the power minimizer SLP is equivalent to the conventional zero-forcing beamforming (ZFBF). This further leads us to a closed-form sub-optimal SLP solution (CF-SLP) for the original problem. Simulation results show that CF-SLP provides significant gains over ZFBF, while performing quite close to the optimal SLP in scenarios with rather small number of users. The results further indicate that the CF-SLP method has a reduction of order $10^3$ in computational time compared to the optimal solution.

arXiv comment7 pages, 1 figure, 1 table, submitted to IEEE signal processing letters

References in corpus (5)

• Exploiting Known Interference as Green Signal Power for Downlink Beamforming Optimization
• Constructive Multiuser Interference in Symbol Level Precoding for the MISO Downlink Channel
• Symbol-Level Precoding Design Based on Distance Preserving Constructive Interference Regions
• Low Complexity Symbol-Level Design for Linear Precoding Systems
• Interference Exploitation Precoding Made Practical: Closed-Form Solutions with Optimal Performance