Combining Spatially Coupled LDPC Codes with Modulation and Detection

Abstract:
In this paper, we illustrate the performance of terminated convolutional LDPC codes in combination with spectrally efficient modulation (as a generic front-end), and show that classic LDPC design philosophies of optimizing degree profiles (and thus seeking for irregularity) are becoming less relevant for spatially coupled codes. We show that with very simple codes (even if regular) we can observe a “universal” behavior, which means that the code performs well regardless of the channel or the detector characteristic.We give two examples of simple coding schemes with one illustrating the universal behavior and show by a simulative example the performance in a practical scenario. We also try to give a pictorial illustration of convergence mechanisms of spatially coupled codes, and distinguish between two different regimes that we coin micro- and macro-convergence, respectively.