An FPGA implementation of low-density parity-check code decoder with multi-rate capability

With superior error correction capability, low-density parity-check (LDPC) has initiated wide scale interests in wireless telecommunication fields. In the past, various structures of single code rate LDPC decoders have been implemented for different applications. However, in order to cover a wide range of service requirements and diverse interference conditions in wireless applications, LDPC decoders that can operate in both high and low code rates are desired. In this paper, a new multi-rate LDPC decoder architecture is presented and implemented in a Xilinx FPGA device. Through selection pins, three operating modes with the irregular 1/2 rate, regular 5/8 rate and regular 7/8 rate are supported. The measurement results show LDPC decoder can achieve BER below 10^-5 at SNR of 1.4dB in the most critical case with the irregular 1/2 mode.