Hardware acceleration for the banded Smith-Waterman algorithm with the cycled systolic array

The Smith-Waterman is one of the most popular algorithms in the molecular sequence alignment. It is often used to find the best local alignment between two strings by calculating the similarity score of the pair of strings. The algorithm is of great potential to be parallelized and has been employed by a lot of FPGA-based solutions, mostly with the systolic array manner. However, the architecture designers always find the number of the process elements (PE) in their implementation quite limited by the resources available on the FPGA devices. They either make decomposition or fold the implementation of their applications when facing a large requirement for the process elements number. In this paper, we put forward a novel FPGA-based architecture which could address the problem with a bounded number of PEs to realize any lengths of systolic array. It is mainly based on the idea of the banded Smith-Waterman but with a key distinguish that it reuses the PEs which are beyond the boundary. Analysis shows that the approach is as fast as the normal systolic fabric and obtains quite considerable resource reduction.