Trellis extracted synchronisation and SNR estimation for turbo codes

Synchronisation is a requirement of all digital communication systems, whil e signal-to-noise ratio estimation is a particular requirement when using t he maximum a posteriori probability algorithm for the iterative stage of a turbo code. The authors address these requirements and provide novel digita l algorithms using the trellis structure of the component codes in a turbo code system. The results show that the algorithms provide the necessary fun ctionality without degradation of performance and, as they are purely digit al solutions, they are suitable for implementation on a digital signal proc essor or field programmable gate array.