Reliability Evaluation of Turbo Decoders Implemented on SRAM-FPGAs

Turbo codes are widely used in satellite communications. When a Turbo decoder is implemented on a Field Programmable Gate Array (FPGA) in a space platform, it will suffer Single Event Upsets (SEUs) that can cause failures and disrupt communications. In this paper, the reliability of Turbo decoders implemented on FPGAs is evaluated. The Turbo decoder with Log-MAP algorithm is implemented on an SRAM-FPGA. Then, fault injection experiments are conducted to simulate the effects of SEU on the user memory and on the configuration memory of the Turbo decoder. Experimental results show that, for user memory, the SEU tolerance rate is over 95%, and the effect of SEU is related to the iteration period, bit position and Signal to Noise Ratio (SNR). In particular, SEUs on the control/address registers and on the interleaving table have a larger impact than on other registers or memories. For the configuration memory, the SEU tolerance rate is higher than 86%, and decreases as SNR increases. In general, the Turbo decoder exhibits a high reliability against SEUs, and the user memory is more reliable than the configuration memory.