Extrinsic information transfer (EXIT) charts have proved to be an effective tool for studying the convergence behaviour of iterative decoders. However, classical EXIT chart analysis fails to assess the performance of turbo codes in which the systematic bits are punctured periodically. A novel three-dimensional (3D) EXIT chart technique is proposed for accurately modelling the convergence behaviour of turbo codes that are punctured following a periodic pattern. Finally, the novel 3D EXIT chart technique is validated for a particular periodic turbo code, which is shown to outperform the equivalent randomly punctured code.
