Structured eIRA codes

In a recent paper, Yang et at. presented the class of extended irregular repeat-accumulate (eIRA) codes which are efficiently encodable LDPC codes possessing very low error-rate floors and are appropriate for code rates 1/2 or greater. While efficiently encodable, the left-most (n - k)-by-k submatrix of an eIRA code parity-check matrix is random in nature, making efficient decoder implementation problematic. In the present paper, we present structured eIRA codes. We first present some ensemble results for the general class of eIRA codes, after which the subclass of structured eIRA codes is defined. Software and hardware-based performance results for structured eIRA code designs (rates 0.5 to 0.9) are then presented. Results include a 0.5(2048, 1024) code with a BER floor at 10/sup -9/ and a 0.8(5120, 4096) code with a BER floor below 10/sup -11/.