Reliability Evaluation and Fault Tolerance Design for FPGA Implemented Reed Solomon (RS) Erasure Decoders

Abstract

Reed-Solomon erasure codes (RS-EC) are widely applied in storage and packet communication systems to recover erasures. When implemented on a Field Programmable Gate Array (FPGA) in a space platform, the RS-EC decoder will suffer Single Event Upsets (SEUs) that can cause failures. In this paper, the reliability of an RS-EC decoder implemented on an FPGA to errors on the configuration memory is firstly studied based on hardware SEU injection experiments. We found that the reliability is lower for larger number of erased symbols, but there are still about 85% SEUs can be tolerated by the decoder itself even for the maximum number of erased symbols within the recovery capability. In addition, around 10%-25% SEUs on critical bits can cause system exceptions. Based on these results, a Duplication With Comparison (DWC) scheme is proposed for the protection of the RS-EC decoder. In particular, a checksum parity based approach is proposed to detect the faulty decoder to reduce the computation overhead. Experimental results show that the reliability of the DWC protected RS-EC decoder to SEUs on the configuration memory is almost the same of a traditional Triple Modular Redundancy (TMR) protection, and the resource usage is only about 2.15× that of the unprotected decoder.