Low-Density Parity Check Codes

Coded modulation is a bandwidth-efficient scheme that integrates channel coding and modulation into one single entity to improve performance with the same spectral efficiency compared to uncoded modulation. Low-density parity-check (LDPC) codes are the most powerful error correction codes (ECCs) and approach the Shannon limit, while having a relatively low decoding complexity. In communication system signal is transmitted and received at the output. But due to various external noise errors occur in the received data in comparison to the transmitted one. To eliminate the errors various error correction techniques are used. LDPC decoder is one such technique. It is the recent technique that is used and it has better performance than the other error correcting techniques in terms of power, reliability and performance. Existing construction method is limited in some way in producing good error correcting performance and easily implementable codes for a given rate and length