A high parallelism LDPC decoder with an early stopping criterion for WiMax and WiFi application

In this paper we propose a synthesizable LDPC decoder IP core for WiMax and WiFi applications. Two new techniques are applied in the proposed decoder to improve the decoding performance. Firstly, a high parallelism permutation network (PN) is proposed to perform the circulant shift according to the parity check matrix (PCM) defined in WiMax and WiFi standards. By using the proposed PN, at most, four independent code frames with small code length are decoded concurrently, which largely improves the decoding throughput (2-4 times). Secondly, a fast early stopping criterion specialized for WiMax and WiFi LDPC code is proposed to reduce the average iteration number. Unlike the early works, by utilizing our proposed stopping criterion, the decoding will be stopped when all the information bits of a code frame are corrected even if there are still some errors in redundant part. Experiment results show that, it can reduce up to 20% iteration numbers compared to popular used stopping criterion.