Design And Optimization Of LDPC Encoder And Decoder In High Speed Wireless Local Area Network

The increasing demand of high data-rate and reliability in modern wireless communication systems requires high-performance er-ror-correction schemes. Besides Turbo codes, LDPC codes are another type of error-correcting code which enjoy near Shannon limit performance. SDR platforms based on general purpose processor architectures, such as commodity PCs, have the opposite set of tradeoffs. Developers program to a familiar architecture and environment using sophisticated tools, and ra-dio front-end boards for interfacing with a PC are relatively inexpensive. With Sora, developers have implemented and experimented with high speed wireless protocol stacks, e.g., IEEE802.11a/b/g, using commodity general purpose PCs. However, IEEE802.11n, the latest protocol of high speed wireless local network, hasn’t been implemented on GPP.LDPC codes are optional channel codes of IEEE802.11n. The opti-mization of LDPC encoder and decoder is necessary for the implementa-tion of IEEE802.11n on GPP. The BER performance of LDPC codes is excellent. However, owing to the high complexity of the decoding algo-rithm, the delay of LDPC decoder is a big obstacle for the throughput of high speed wireless local network. Based on the research of the Qua-si-Cyclic LDPC codes structure, this paper chooses proper decoding algo-rithm and optimizes both LDPC encoder and decoder on GPP to meet the throughput demand of IEEE802.11n.Test results show that the LDPC encoder and decoder based on GPP can meet the throughput demand of IEEE802.11n, laying good foundation for the implementation of wireless local area network system based on software radio.