Polar Reed-Solomon concatenated codes for optical communications

Abstract

A concatenated forward error correcting (FEC) code is developed by targeting optical communications. Polar and product Reed-Solomon (RS) codes are used as inner and outer codes, respectively. An interleaver block is designed to align multiple inner code blocks. Target key parameter indicators (KPIs) for the decoder circuitry are set to 1 Tb/s throughput and 10 mm2 area occupation. These KPIs narrowed the design space down to the simplest decoding algorithms in moderate block-lengths. Soft information from the channel is collected by a polar decoder. Minimum distance between codewords is increased by a product code with two error correcting RS codes. Performance of the developed FEC code is evaluated based on its communications performance, decoding complexity and area occupation. Code configurations are designed with overheads of 15%, 20%, 24% and 28% supporting 1 Tb/s throughput. In one configuration, 11.3 dB net coding gain is estimated at 10−15 bit error rate (BER). Area of the decoder circuitry is estimated to be 14.27 mm2 in 28nm while supporting 1 Tb/s throughput.