ATE-GCN: An FPGA-Based Graph Convolutional Network Accelerator with Asymmetrical Ternary Quantization

Ruiqi Chen, Jiayu Liu, Shidi Tang, Yang Liu, Yanxiang Zhu, Ming Ling, Bruno Da Silva

Abstract: Ternary quantization can effectively simplify matrix multiplication, which is the primary computational operation in neural network models. It has shown success in FPGA-based accelerator designs for emerging models such as GAT and Transformer. However, existing ternary quantization methods can lead to substantial accuracy loss under certain weight distribution pat-terns, such as GCN. Furthermore, current FPGA-based ternary weight designs often focus on reducing resource consumption while neglecting full utilization of FPGA DSP blocks, limiting maximum performance. To address these challenges, we propose ATE-GCN, an FPGA-based asymmetrical ternary quantization GCN accelerator using a software-hardware co-optimization approach. First, we adopt an asymmetrical quantization strategy with specific interval divisions tailored to the bimodal distribution of GCN weights, reducing accuracy loss. Second, we design a unified processing element (PE) array on FPGA to support various matrix computation forms, optimizing FPGA resource usage while leveraging the benefits of cascade design and ternary quantization, significantly boosting performance. Finally, we implement the ATE-GCN prototype on the VCU118 FPGA board. The results show that ATE-GCN maintains an accuracy loss below 2%. Additionally, ATE-GCN achieves average performance improvements of $224.13\times$ and $11.1\times$, with up to $898.82\times$ and $69.9\times$ energy consumption saving compared to CPU and GPU, respectively. Moreover, compared to state-of-the-art FPGA-based GCN accelerators, ATE-GCN improves DSP efficiency by 63% with an average latency reduction of 11%.