Design and comparison of turbo codes under frame-length and code-rate constraints

When the performances of error-correcting codes for space communications are investigated, with the aim to translate them into practical recommendations, comparison among different schemes is usually a very difficult task. As a matter of fact, these comparisons rarely yield general conclusions. On the other hand, most practical space applications impose strong constraints on the code parameters, which have important effects on code selection. In this paper, we show a methodology and several examples of design and comparison, derived under fixed constraints imposed by the system application on the frame-length and the code-rate. CCSDS Earth observation missions requiring both large coding gains and high spectral efficiency are considered as a case study. Though referred to this specific space mission framework, the presented study is quite general and applies to many other digital communication systems; e.g. for wireless or wired applications where similar constraints exist but are often not taken in due consideration by the designer of the error-correcting schemes.