Selective symbol level precoding for multibeam satellite communication systems

Multibeam satellite communication systems have emerged as a promising solution for enhancing spectrum efficiency and user connectivity in next-generation wireless networks. However, the performance of such systems often degrades due to severe multi-user interference resulting from aggressive frequency reuse and beam overlap. To address this, Symbol-Level Precoding (SLP) has been proposed for its ability to exploit constructive interference and improve signal quality beyond traditional block-level techniques. Despite its advantages, SLP suffers from high computational complexity, limiting its practicality for real-time applications in satellite systems with constrained processing resources. In this paper, we propose a novel Selective Symbol-Level Precoding (SSLP) method that significantly reduces the computational burden while maintaining near-optimal performance. First, we introduce a symbol selection technique that classifies transmitted symbols as either constructive or destructive based on known Channel State Information (CSI) and noise conditions. Then, we selectively apply SLP only to destructive symbols while directly transmitting constructive ones, thus reducing unnecessary optimization. Furthermore, we extend the proposed method to coded systems by dropping destructive symbols during transmission and reconstructing them using channel decoding. Simulation results show that SSLP achieves up to 70% reduction in computational complexity, while incurring a maximum Bit Error Rate (BER) degradation of approximately 2 dB compared to conventional SLP. By dynamically adjusting the number of precoded symbols, SSLP enables a flexible trade-off between performance and complexity, making it well-suited for next-generation multibeam satellite communication systems.