FPGA implementation of Reed Solomon codec for 40Gbps Forward Error Correction in optical networks

Reed-Solomon error correcting codes (RS codes) are widely used in communication and data storage systems to recover data from possible errors that occur during data transfer. A growing application of RS codes is Forward Error Correction (FEC) in the Optical Network (OTN G.709), which uses RS(255,239) to support the OTU-3 (43.018 Gbps) standard. There have been considerable efforts in the area of RS architecture for ASIC implementation. However, there appears to be little reported work on efficient RS codec (encoder and decoder) for Field Programmable Gate Arrays (FPGAs), which has increasing interests in industry. This thesis investigates the implementation and design methodology of the RS(255,239) codec on FPGAs. A portable VHDL code is developed and synthesized for Xilinx\u27s Virtex4 and Altera\u27s StratixII. The FPGA architectures are analyzed and the required design methodologies are adopted to efficiently utilize the available resources. Unfortunately, due to the fixed size of FPGA devices, the RS decoder is not only constrained by the required timing of the system, but also by the size of the targeted device. This research will facilitate the decision-making process for selecting a reconfigurable device for a RS decoder, implementing the Berlekamp-Massey Algorithm

Profile Guided Dataflow Transformation for FPGAs and CPUs

This paper proposes a new high-level approach for optimising field programmable gate array (FPGA) designs. FPGA designs are commonly implemented in low-level hardware description languages (HDLs), which lack the abstractions necessary for identifying opportunities for significant performance improvements. Using a computer vision case study, we show that modelling computation with dataflow abstractions enables substantial restructuring of FPGA designs before lowering to the HDL level, and also improve CPU performance. Using the CPU transformations, runtime is reduced by 43 %. Using the FPGA transformations, clock frequency is increased from 67MHz to 110MHz. Our results outperform commercial low-level HDL optimisations, showcasing dataflow program abstraction as an amenable computation model for highly effective FPGA optimisation