Construction and performance analysis of moderate-length rate-compatible LDPC codes

Rate-compatible coding is appropriate for communication systems that may experience a range of operating SNRs but that seek to adhere to a single underlying codec structure. This paper proposes two special and efficient approaches: extending and information ing, to build low rate codes from high rate LDPC codes (mother codes) of moderate length (10³4). Both the two proposed approaches result in better performances than punctured RC-LDPC codes at low code-rates. Extending leads to good performance at rate about 0.4∼0.6, but which has not so good performance at high rates (about 0.6∼0.8). The threshold of extended code rates is pointed out for the first time, which rests with the code-rate of the mother code. Information ing, which results in acceptable performance at high rates, and also good performance at low rates without any threshold of code rates, is confirmed to have a wider rate range and lower computation complexity than extending.