Branch synchronisation schemes for convolutional codes

Two simple branch synchronisation schemes for a class of single-generator binary convolutional codes are presented in this paper. The first scheme is based on the selection of the generator sequences from a set of codes defined to have self-synchronisation property. This scheme is very useful for low rate codes with long constraint length, and its complexity is independent of the encoder/decoder configurations. The second scheme is proposed for codes with short constraint length. Analysis shows that both schemes have an upper bound of b.e.r. = 50% which significantly exceeds the synchronisation capabilities of existing systems. In addition, these two schemes can obtain branch synchronisation and resolve phase ambiguity of the received signal at the same time.