High Rate LDPC Based Decoder Architectures with High Speed ADC for C-RAN Optical Fronthaul

Abstract

In this paper we study the design of LDPC decoding scheme for very high throughput optical communications for a full self-seeded optical architecture dedicated to cloud radio access network (C-RAN). The objective of this paper is to demonstrate the potentiality of Bit Flipping (BF) algorithms. It is shown that the Gradient Descent Bit Flipping (GDBF) algorithm with a little improvement is suitable for high speed applications. With a simple high-speed two-bit Analog to Digital Convertor (ADC) we show that we can obtain a BER of as low as 10-9 for an input BER of 10-4. Furthermore, the proposed decoder achieves a BER of at least 10-7 after just one iteration. It is necessary for real time applications to reduce the decoding delay. We propose a simple FPGA implementation that gives 500 Mb/s. The guidelines are also suggested to increase the throughput up to 2.5 Gb/s, required by CRAN application.