Low-Complexity Designs of Symbol-Level Precoding for MU-MISO Systems

TL;DR

This paper introduces a low-complexity grouped symbol-level precoding method for multi-user MISO systems that maintains performance while significantly reducing computational demands.

Contribution

The paper proposes a novel G-SLP approach that divides users into groups and designs precoders per group using efficient algorithms, reducing complexity compared to traditional methods.

Findings

Significant reduction in computational complexity.

Maintains comparable symbol-error-rate performance.

Effective suppression of inter-group multi-user interference.

Abstract

Symbol-level precoding (SLP), which converts the harmful multi-user interference (MUI) into beneficial signals, can significantly improve symbol-error-rate (SER) performance in multi-user communication systems. While enjoying symbolic gain, however, the complicated non-linear symbol-by-symbol precoder design suffers high computational complexity exponential with the number of users, which is unaffordable in realistic systems. In this paper, we propose a novel low-complexity grouped SLP (G-SLP) approach and develop efficient design algorithms for typical max-min fairness and power minimization problems. In particular, after dividing all users into several groups, the precoders for each group are separately designed on a symbol-by-symbol basis by only utilizing the symbol information of the users in that group, in which the intra-group MUI is exploited using the concept of constructive interference (CI) and the inter-group MUI is also effectively suppressed. In order to further reduce the computational complexity, we utilize the Lagrangian dual, Karush-Kuhn-Tucker (KKT) conditions and the majorization-minimization (MM) method to transform the resulting problems into more tractable forms, and develop efficient algorithms for obtaining closed-form solutions to them. Extensive simulation results illustrate that the proposed G-SLP strategy and design algorithms dramatically reduce the computational complexity without causing significant performance loss compared with the traditional SLP schemes.