A Block-Based Systolic Array on an HBM2 FPGA for DNA Sequence Alignment

Revealing the optimal local similarity between a pair of genomic sequences is one of the most fundamental issues in bioinformatics. The Smith-Waterman algorithm is a method that was developed for that specific purpose. With the continuous advances in the computer field, this method becomes widely used to an extent where it expanded its reach to cover a broad range of applications, even in areas such as network packet inspections and pattern matching. This algorithm is based on Dynamic Programming and is guaranteed to find the optimal local sequence alignment between two base pairs. The computational complexity is O(mn), where m and n are defined as the number of the elements of a query and a database sequence, respectively. Researchers have investigated several manners to accelerate the calculation using CPU, GPU, Cell B.E., and FPGA. Most of them have proposed a data-reuse approach because the Smith-Waterman algorithm has rather high "bytes per operation"; in other words, the Smith-Waterman algorithm requires large memory bandwidth. In this paper, we try to minimize the impact of the memory bandwidth bottleneck through the implementation of a block-based systolic array approach that maximizes the usage of memory banks in HBM2 (High Bandwidth Memory). The proposed approach demonstrates a higher performance in terms of GCUPS (Giga Cell Update Per Second) compared to one of the best cases reported in previous works, and also achieves a significant improvement in power efficiency. For example, our implementation could reach 429.39 GCUPS while achieving a power efficiency of 7.68 GCUPS/W. With a different configuration, it could reach 316.73 GCUPS while hitting a peak power efficiency of 8.86 GCUPS/W.