On the Error-Rate Performance of 4-State Turbo Codes With Puncture-Constrained DRP Interleavers
It has often been demonstrated that conventional 4- state turbo codes do not perform well in either the waterfall or error-rate flare regions due to poor inherent convergence and distance properties, especially for highly-punctured codes. This paper shows that the opposite can be true when carefully chosen data and parity puncture masks are used with matching puncture-constrained Dithered Relative Prime (DRP) inter-leavers. Turbo codes were first introduced in. The example Turbo Code (TC) consisted of a data inter-leaver between two parallel and identical (symmetric) binary 16-state rate-1/2 Recursive Systematic Convolutional (RSC) codes with Feed-Back (FB) and Feed-Forward (FF) polynomials (FB,FF) = (37,21) octal.