Graph Neural Network for Location- and Orientation-Assisted mmWave Beam Alignment

In massive multi-input multi-output (MIMO) systems, the main bottlenecks of location- and orientation-assisted beam alignment using deep neural networks (DNNs) are large training overhead and significant performance degradation. This paper proposes a graph neural network (GNN)-based beam selection approach that reduces the training overhead and improves the alignment accuracy, by capitalizing on the strong expressive ability and few trainable parameters of GNN. Due to the spatial correlation, the channels of beams with similar beam directions are generally correlated. Therefore, we establish a graph structure according to the angular correlation between beams and use GNN to capture the channel correlation between adjacent beams, which helps accelerate the learning process and enhance the beam alignment performance. Compared to existing DNN-based algorithms, the proposed method requires only 20% of the dataset size to achieve equivalent accuracy and improves the Top-1 accuracy by 10% when using the same dataset.