Low Complexity Subset Precoding for High Throughput Satellite Systems

Precoding is a well-known method for interference mitigation that enables a high throughput satellite (HTS) multi-beam system to step up from traditional 4-coloring (FR-4) to a full frequency re-use (FR-1) but challenges the resources with high computational complexity. The calculation of the optimum precoding matrix and the number of complex multiplications are the two most challenging tasks in terms of computational complexity to accomplish when using this interference mitigation method. In this article, we tackle the first problem by utilizing a MMSE approach to determine the precoding matrix and focus instead on the latter. We propose a method to reduce the number of required complex multiplications in the gateway. The performance is evaluated based on different antenna patterns to identify crucial antenna pattern characteristics that define the number of required multiplications. The results indicate that the number of multiplications can be reduced depending on the present SNR and side lobe levels in the antenna pattern.